Ph.D. - Biomedical Sciences (Physiology)

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Chronic exposure to an insulin-containing lipogenic stimulus results in ectopic cytoplasmic lipid accumulation and altered pro-inflammatory function in mast cells
(University of Hawaii at Manoa, 2013-05) Greineisen, William Ernest
This thesis presents evidence that mast cells (MC) chronically exposed to insulin respond by developing steatotic levels of cytosolic lipid bodies, suggesting that immunocytes, like hepatocytes and myocytes, are sites of lipid sequestration in response to dysregulated insulin levels. This ectopic lipid accumulation influences mast cell functionality, biasing mast cell phenotype towards the production of bioactive lipid mediators (LTC4) and away from the release of histamine and other secretory granule components. In the current study we present an analysis of the whole cell and lipid body lipidome in control, and insulin-exposed mast cells. Our data show a significant upregulation in lipid-associated pro-inflammatory precursor molecules in response to chronic insulin exposure. We also show that the lipid body population in these cells are heterogeneous to a previously unsuspected degree. Moreover, due to the intimate relationship between the endoplasmic reticulum (ER) and lipid body production, we tested the hypothesis that the ER may be altered in response to chronic insulin exposure. Indeed, our data show that (in a manner analogous to observations in hepatocytes from obese models) the ER is reprogrammed towards a lipogenic phenotype, is morphologically distended, is compromised as a calcium store and exhibits certain indicators of a unfolded protein response (UPR)/ER stress response in response to chronic insulin. Taken together, these data show that chronic insulin exposure in a model mast cell system drives lipidomic remodeling in a manner that alters lipid body formation and mast cell proinflammatory function.
Detection of cortical arousals in sleep EEG
(University of Hawaii at Manoa, 2010-12) Collin, Herve
Introduction: Cortical arousals (CA) are a transient part of the sleep-wake system that may play an important role in characterizing sleep fragmentation and disorders, such as obstructive sleep apnea. The American Association of Sleep Medicine (AASM) (1992) rules describe electroencephaolgram (EEG) frequency ranges, as well as electromyogram (EMG) signal morphology to identify CA; however, because of a lack of reliability in arousal detection, even among well-trained human scorers employing the AASM rules, CA has had limited efficacy in describing healthy sleep and/or in diagnosing sleep pathology. The purpose of this study is to increase the reliability of CA detection utilizing Power Spectrum Density (PSD). The exact frequency bands needed for CA detection for each sleep stage will be identified. It will be tested whether or not, the submental activity is necessary in slow wave sleep (SWS) to increase the reliability of CA detection. Methods: Previously recorded 30-second EEG sleep epochs from healthy adult subjects (N = 99) were examined in this study. The average and standard deviation of the relative powers of all frequency bands (Delta, Theta, Alpha, Sigma, Beta1, Beta2, and Gamma) were computed for all epochs and sorted by sleep stages. Using EEG activity, the relative power of specific frequency bands was compared to the average plus a multiple of the standard deviation for the purpose of detecting CA in each sleep epoch. EMG activity was also included for all sleep stages. The average and standard deviation of the relative amplitudes were then computed for all epochs and sorted by sleep stages. For each sleep stage, CA detection was achieved by comparing the standard deviation of the amplitudes to a multiple of the averages of the standard deviations. This experimental scoring technique was then compared with EEG epoch data scored by the Sleep Heart Center Study (SHHS) sleep scientists. An estimate of reliability was obtained using the Cohen kappa, sensitivity, and specificity measures. Results: Optimum CA detection entailed using a combination of different explicit frequency ranges for different respective stages. Based on the reliability calculated from the Cohen kappa, the optimum frequency bands for stage1 were: Beta1 (16-24 Hz), stage2: Beta1 (16-24 Hz), stage3: Beta1 and Gamma (24-48 Hz), stage4: Beta1 and Gamma (24-48 Hz), and stage REM: Delta, Alpha, Beta1, and Gamma (0-4, 8-12, 16-24 and 32-48 Hz). It was also found that the use of EMG for NREM sleep stages increased the sensibility. The corresponding statistical measures for all sleep stages were: Sleep Stage Cohen kappa Sensitivity Specificity Stage1 0.16±0.025 63±3% 56±2% Stage2 0.35±0.025 61±3% 81±1% Stage3 0.48±0.050 60±5% 96±1% Stage4 0.73±0.170 73±15% 98±2% Stage REM 0.48±0.030 58±3% 93±1% Conclusion: Careful consideration of the frequency band is necessary in order to increase the reliability of the detection of CA in EEG. Submental activity was also found to increase the reliability of CA detection in sleep stages SWS. Moreover, incorporating submental activity similarly increases most statistical measures. In conclusion, the AASM rules for detecting CA in EEG would be improved if the criteria included specific frequency ranges and submental activity in SWS sleep stages.
Differential gene expression in mice with misexpression of Six2 associated with frontonasal dysplasia
(University of Hawaii at Manoa, 2012-08) Hynd, Thomas Eugene
We have previously described the Br mutant mouse displaying heritable frontonasal dysplasia. Linkage analysis mapped the mutation near the homeobox transcription factor Six2, normally expressed in the facial and metanephric mesenchyme during development. The purpose of this study is to determine expression patterns of Six2, as well as possible downstream targets of Six2, in the developing midface. The three sets of facial prominences (medial, lateral, and maxillary) from embryos at gestational day 11.5 (E11.5) were dissected and RNA extracted for qRT-PCR assays and microarray analysis. Medial nasal prominences (MNP) and E13.5 kidneys were also taken for cell culture. Results from qRT-PCR indicated Six2 expression is highest in the MNP at E11.5 and demonstrated haploinsufficient down-regulation in each of the three facial prominence sets in the Br mouse at this age. Microarray results suggested the misregulation of several genes in the Br midface, including Six3, another member of the Six family of transcription factors. MNP and kidney qRT-PCR and immunohistochemistry for Six3 substantiated its upregulation in the microarray. Additionally, Shh and Flrt2 were confirmed misexpressed in the developing midface, both of which have been previously shown to play critical roles in craniofacial development. RNA interference on Six2 in E11.5 MNP and E13.5 embryonic kidney cultures did not demonstrate misexpression of Six3, suggesting Six2 is not a direct regulator of Six3 and that the Br mutation may be located in a transcriptional activation domain of Six2 that also inhibits Six3 transcription. Further sequencing analysis will be needed to confirm the type and location of the Br mutation. This work was supported, in part, by NIH R01DK064752 & NCRR 5P20RR024206.
Divalent cation channels with intrinsic alpha-kinase activity
(University of Hawaii at Manoa, 2005) Bessac, Bret Fajans
The role of human serum albumin and its structural variants in coronary heart disease
(University of Hawaii at Manoa, 2004) Ha, Ji-Sook
Temporal effects of prenatal ethanol exposure on the hypothalamo-neurohypophyseal system in the rat (Rattus norvegicus)
(University of Hawaii at Manoa, 2004) Lim, Jenny M.
An analysis of calcium dependent proteolysis in yellowfin tuna (Thunnus albacares) muscle
(University of Hawaii at Manoa, 1990) Watson, Cheryl Lynn
ADH response to peripheral and central cortisol administration
(University of Hawaii at Manoa, 1987) Cornette-Finn, Kuuleialoha M.
Cortisol affects water balance, but whether this effect is mediated through antidiuretic hormone (ADH) is unclear. This study examines the response of plasma ADH (pADH) in two groups of conscious dogs; one received cortisol centrally (ivt) in the third ventricle at 300 ng/min, the other peripherally (iv) at 4.16 µg/kg/min, in 4 states of water balance, i.e., dehydration, normal hydration, 5% NaCl iv infusion (0.05 ml/kg/min), and after a water load (40 ml/kg given iv over 30 min), as compared to control experiments without cortisol. Cortisol, either ivt or iv, had no affect on pADH or plasma osmolality (pOsm) during dehydration or normal hydration. Ivt cortisol infusion caused a progressive decline in plasma cortisol (pCort) while iv cortisol infusion increased pCort (control 2.0 µg%, ivt pCort 0.5 µg%, iv pCort 17 µg%, P<0.01). During the 5% NaCl iv infusion, pADH and pOsm increased similarly in both the control and ivt cortisol experiments from 1.0 to 1.9 µU/ml and 295 to 305 mOsm/kg H2O, respectively (P<0.01). The increase in pADH seen with 5% NaCl infusion was delayed in the iv cortisol experiment as compared to the iv control (75 min versus 45 min, P<0.01). This delay was also seen in pOsm; 45 min in iv cortisol versus 15 min in iv control (P<0.01), indicating that the elevated pCort apparently delays the development of increased pOsm and the subsequent increase in pADH. During a water load, the cumulative urine excreted was 99% of that ingested with iv cortisol (P<0.05), 82% in the control, and 70% with ivt cortisol; in all three cases similar decreases in pADH and pOsm occurred. The free water clearance (FWC) was augmented in the iv cortisol infusion and attenuated in the opposite situation of pCort insufficiency which was established during the ivt cortisol infusion. Thus, the present study demonstrates that cortisol has a peripheral effect in that elevated plasma cortisol 1) delays the rise in pOsm during hypertonic saline infusion 2) increases FWC during a water diuresis but 3) does not alter the pADH versus pOsm relationship, therefore 4) affects the ability to excrete a water load independent of ADH. These data are compatible with a mechanism in which excess cortisol enhances the Na+ "leak" pathway of the cells by increasing the membrane permeability to Na+, thereby increasing the osmolar content of the cells.
The role of complement and neutrophils in air bubble-induced lung injury
(University of Hawaii at Manoa, 1995) Huang, Kun-Lun
Pulmonary air embolism causes vascular obstruction and induces biochemical reactions leading to lung injury. In the present study, by using isolated and perfused rat lungs, we investigated the involvement of the complement system and polymorphonuclear leukocytes (P:MN) in the alterations of segmental vascular resistances, lung weight gain, and filtration coefficient (K), a measure of vascular permeability. After establishing ventilation with air and 5% CO2, the lung was removed en bloc and suspended in a humidified chamber at 37°C. Lung weight, arterial and venous pressures were monitored continuously. Lungs were perfused with physiological salt solution (PSS) containing 4% Ficoll. We used 6 series of perfusates containing: 1) PSS, 2) PMN, 3) plasma, 4) decomplemented plasma, 5) PMN and plasma, and 6) PMN and decomplemented plasma. Air embolism, induced by a 0.76-ml air infusion to arterial catheter in 20 min, increased arterial pressure without altering capillary and venous pressure, suggesting that the increased arterial resistance alone was responsible for the pulmonary hypertension. In lungs perfused with both PMN and normal plasma, air embolism increased Kf by 145 ± 190% which was significantly greater than those in lungs perfused with either PMN (91 ± 8%), plasma (90 ± 8%), or PMN and decomplemented plasma (80 ± 9%). Air embolism increased Kf by 45 ± 12% in the lungs perfused with decomplemented plasma, which was the least among groups. These results suggest that air embolism damages the lung by hypertension, activation of the complement, and activation of PMN, singly or in combinations. The modulation role of PMN in air bubble-induced lung injury was investigated by pretreating the lungs with blocking agents of the cytotoxic substances released from PMN. The lungs perfused with both P:MN and normal plasma served as the control group. In lungs pretreated with scavengers, air embolism increased Kr by 108 ± 25% which was not different from the control group. Air embolism induced little change of Kf in the lungs pretreated with indomethacin (17 ± 8%) or isoproterenol (0 ± 9%), suggesting that air embolism increases pulmonary vascular permeability involving the release of arachidonic acid metabolites.
Bioenergietics of the bottlenose dolphin (Tursiops truncatus)
(University of Hawaii at Manoa, 1995) Magee, Michelle Coyne
There are numerous species of marine mammals found throughout the earth's oceans and waterways. The study of marine mammal energetics is an attempt to define the flow of energy in homeotherms adapted to an aqueous environment. Their lifestyle is different than terrestrial mammals and must compensate for the challenging thermoregulatory requirements of water survival. Field studies of free-ranging animals are difficult, since continual direct observation and measurements are impossible. It is important to conduct controlled laboratory studies, from which to build a foundation of physiological principles on these mammals. The objectives of this research project were to investigate the bioenergetic scheme of the bottlenose dolphin under controlled laboratory-like conditions. Morphometric data in a large bottlenose dolphin population established an equation to predict age from length measurements in juvenile animals. The decrease in caloric intake seen with aging is in agreement with terrestrial mammals, and the importance of nutritional planning based on calories per kilogram body weight versus total calories fed was explained. Increased activity levels required increased caloric consumption, the amount being related to the degree of activity. A recently developed method to assess blubber volume using ultrasound are compared to standard measurements of body condition, weight-length ratio and condition index, and found to be a valid technique in this species. Blubber insulation was found to be more important than surface area in controlling environmental heat loss. Using stable isotopes of water, body composition, lean body mass and fat mass, were determined. An increase in fat mass, with a concurrent decrease in lean body mass, was observed in adult bottlenose dolphins, similar to terrestrial mammals. Also, consumption of a high fat diet contributed to an increase in body fat. Metabolic rates declined with age in bottlenose dolphins, and a significant increase was observed with low fat diets. Finally, the use of doubly labeled water to determine metabolic rate in free-ranging bottlenose dolphins was compared to the intake balance method and found to be an accurate technique in this species. The drawbacks of controlled laboratory trials is that, although all attempts are made to mimic diets and conditions that exist in the wild, the methods are only an approximation of wild conditions. The advantages are the ability to isolate and evaluate individual parameters and ensure adequate and timely data collection. It is essential to combine laboratory and field studies in order to elucidate the bioenergetic mechanisms and physiological adaptations of marine mammals. Although marine mammals have evolved specialized compensatory adaptations to ensure success in an aquatic environment, they follow the same general principles observed in terrestrial mammals. This research supports the concept of evolution and the relationship of all homeotherms, despite differences in ecological niches.
Cardiorespiratory responses to slight expiratory resistive loading during strenuous exercise at sea level
(University of Hawaii at Manoa, 1995) Fee, Larry L.
At sea level we determined the cardiorespiratory and performance effects of a slight expiratory resistive load (ERL) which, at mild altitude, had been effective in mitigating exercise-induced hypoxemia (EIH). Paired VO2max bicycle ergometer tests, (ERL vs control) were performed by 28 highly-fit (VO2max = 63.4 ±. 1.36) athletes (age = 33.5 ± 7.3). There was significant EIH in both control and ERL tests at 75, 80, 85. and 90% maximum power output (POmax) and at VO2max when compared to resting SaO2; but no difference in SaO2 between control and ERL at any level of intensity. Peak-expiratory mouth pressures (Pao) were greater (p≤0.05) with ERL at 75, 80, 85, 90 % POmax and VO2max: with ERL, Pao was increased compared to control by 0.20, 0.35, 0.41, 0.49, and 0.73 cm H2O, respectively. Concomitantly, minute ventilation (VE) was greater with ERL vs control (p≤0.05) by 4.1, 4.9, 4.5, and 5.8 L min^-1 at 80, 85, 90 % POmax and VO2max. The increase in VE was largely due to a trend toward increased tidal volume (.1 ml = 121, 198, 154, and 103, from 75 to 90 % POmax). There was a small, non-significant increase in VO2 (averaging 3.0 ml kg^-1-sec^-1) with ERL from 75-90 % POmax. With ERL, heart rate (HR) was consistently lower (≥ 2.0 BPM) throughout, although not significantly so. However, O2 pulse (VO2/ HR) was significantly greater with ERL by 9.5, 9.0, 7.9, 7.1 and 7.0 % at 75, 80, 85, 90 % POmax and V02max. With ERL, athletes attained greater (p ≤ 0.05) POmax 352.0 ±. 9.9 vs 345.7 ±. 9.5 watts, and higher (p ≤ 0.05) VO2max = 63.4 ±. 1.36 vs 60.3 ±. 1.26 ml kg^-l min^-1. Subsequently, in a subset (n =12), FRC was determined by He-dilution during steady-state 75 % POmax. With ERL, Pao VE, and VT/Te were greater (p<0.05) and FRC was elevated (p≤0.05) 0.67 ±. 0.29 L. End-inspiratory lung volume (EILV) with ERL was greater than control (p≤0.05), 82.2 ±. 1.1 vs 72.5 ±. 1.3 % of TLC, respectively. We conclude that during heavy to intense exercise, surprisingly small ERL (ranging from 1.27 to 2.94 cm H2O) may cause VT to increase and FRG to shift upward, reducing the potential for air flow limitation. That O2 pulse was higher with ERL at workloads identical to that of control, would suggest that venous return was augmented, perhaps in response to reduced pulmonary vascular resistance associated with increased FRG. The significantly improved VO2max with ERL may be due in part to the increased inspiratory work of breathing that exercising at elevated FRCs may entail; however, it would appear that some fraction of the increased VO2max observed with ERL was delivered to the working skeletal muscle which produced significantly greater POmax. We conclude that during strenuous exercise, slight expiratory resistive loading enhances performance in highly-trained athletes.
The effect of age and gender on the peripheral blood cell response to Escherichia Coli lipopolysaccharide (lps) in Wistar rats (Rattus Norvegicus)
(University of Hawaii at Manoa, 1994) Merritt, Deborah J.
Escherichia coli (E. coli) lipopolysaccharide (LPS) is the major component of mammalian gut bacterial flora. Inflammatory diseases of unknown etiology, e.g., rheumatoid arthritis, may be triggered by periodic transmural release of LPS from the gut into the peritoneal cavity. If so, an older animal should have a greater exposure history to LPS and, therefore, be hyper-responsive. Age and gender-related variation in peripheral blood cell responsiveness was determined in untreated rats (time zero). The acute (0-2 day) and long-term (3-24 day) response to an intraperitoneal injection of 0.5 mg/kg E. coli LPS was compared to control (sterile 0.9% saline) in young, middle-aged, and old male and female Wistar rats. In untreated rats, a number of parameters changed with age: older rats had increased white blood cell (WBC) chemiluminescence (CL) , time-to-peak CL, plasma protein concentration, and decreased WBC total count, and in vitro WBC mobility. Packed cell volume (PVC) increased in middle-age, but decreased in old rats. Saline-treated male rats had higher WBC counts, body weight, CL, and PVC when compared to age-matched, saline-treated, female rats. Acutely, LPS caused a hypothermia in all rats, which was more profound and prolonged in the old rats. Hypothermia was followed by fever, which was highest in the young rats. LPS also increased WBC counts and CL, and decreased time-to-peak WBC CL in all rats. WBC CL was greater in old and middle-aged rats during days 13-24 following LPS. Blood-free, homogenized, liver cell CL tripled in old age. These findings suggest that LPS was a pro-inflammatory stimulant, particularly in the middle-aged and old rats. Interestingly, this effect of LPS appears to eliminate many age and gender effects noted in the untreated animals. The observation that a single I.P. injection of LPS has no effect on WBC CL during the first three hours and increases CL during hours 3-48 in all but the old female group, and that the old female rats' WBC CL was depressed during the first 12 hours and enhanced at hour 48, may explain some of the conflicting observations made by others using shorter protocols.
Comparative physiology of dipeptide transport in lower vertebrates (fishes) and invertebrates (lobster)
(University of Hawaii at Manoa, 1994) Thamotharan, Manikkavasagar
In my study I propose to undertake an investigation to characterize the brush border uptake and basolateral efflux mechanisms of a biologically stable dipeptide, glycylsarcosine in an herbivorous teleost (tilapia, Oreochromis mossambicus.). This will be the first study to characterize dieptide uptake and efflux processes of a single dipeptide in any animal. In order to extend our understanding of such a unique system, I would like to compare the characteristics of brush border uptake in the herbivorous tilapia to those of a carnivorous teleost (rock fish, Sebastes caurinus) and an omnivorous invertebrate (lobster, Homarus americanus). The lobster hepatopancreas is a diverticulum of the pyloric stomach. Over the past few years a number of studies have focused on the mechanism of sugar and amino acid transport by hepatopancreatic BBMV (4,5). These investigations showed that the hepatopancreas plays a major role in the absorption of nutrients in this animal. A novel feature of these diverticula is that the luminal pH at times of feeding may drop to as low as 4 (18). A number of studies have shown that a drop in external pH stimulates sugar and amino acid transport into hepatopancreatic BBMV. The observed stimulation was attributed either to protonation of amino acids with the protonated form being the preferred substrate, or protonation of the carrier resulting in an increase in the binding affinity for the sugars. The acidic nature of these diverticula at the absorptive site, markedly affecting nutrient transport, make this an ideal animal model since the solutes under investigation (dipeptides) are known to be coupled to protons in other types of animals. It will be of interest to investigate: (1) whether such a proton coupled dipeptide mechanism exists in the brush border membrane of lobster hepatopancreas, (2) If so, are the affinities and transport capacities of these dipeptide transporters any different than those described for mammals and fishes, (3) Does the binding affinity of this transporter show any variation at different pH values?, and (4) Is the specificity of this transporter any different from those exhibited by vertebrates?
Alcohol metabolism in a multi-ethnic population: simultaneous determination of plasma ethanol, acetaldehyde and acetate using gas chromatography in subjects of Asian and European descent and correlation of concurrent cardiovascular responses
(University of Hawaii at Manoa, 1994) Fairman, Colin L.
Cardiovascular and hormonal responses to hypotension during hypoxia in the conscious goat
(University of Hawaii at Manoa, 1993) Eichinger, Mark R.
The cardiovascular and hormonal responses to hemorrhage and chemically-induced hypotension in conscious goats were assessed in the present study. A progressive hemorrhage (0.5 ml/kg/min for 30 min) under hypoxic (FiO2=0.10) conditions (HH, n =4) reduced mean arterial blood pressure (MABP) after only 20 min of blood loss. An identical hemorrhage under normoxic conditions (NH, n =4) did not reduce MABP until after the blood loss was complete. Heart rate (HR) was significantly increased with hemorrhage only during normoxia. Arginine vasopressin (AVP) responses followed MABP chances, with HH levels being greater at an earlier time point. Final AVP values were not different between NH and HH. Plasma renin activity (PRA) responded in near identical fashion between the two settings, despite the earlier reduction in MABP with HH. Atrial natriuretic factor (ANF) was reduced during hemorrhage with both exposures. Sodium nitroprusside (SNP) infusions sufficient in reducing MABP 20% increased HR only during normoxia (NH, n =4). HR was not changed with hypotension during hypoxia (HH, n =4). AVP levels were increased with SNP infusions during both exposures, with HH values greater than NH. PRA and epinephrine (EPI) increased in similar fashion during NH and HH. Norepinephrine (NE) and ANF were unchanged with SNP induced hypotension. Finally, an acute 60 minute hypoxic exposure increased HR within the first 10 minutes. No transient increases in MASP, plasma NE or EPI were detected over the 60 min period of hypoxia. Thus, hemorrhage during hypoxia poses a greater challenge to the cardiovascular system than does an equal blood loss during normoxia. Further, it appears that hypoxia attenuates the PRA response to hemorrhage. However, when MASP is reduced over an identical time frame during normoxia and hypoxia, no differences in the PRA responses can be observed, while a hypoxic augmentation of the AVP response to hypotension becomes apparent. Finally, the data suggest a hypoxic attenuation of the arterial baroreflex tachycardia with hypotension in conscious goats.
Relaxin and prolactin secretion from the human decidual cell: regulation in vitro
(University of Hawaii at Manoa, 1992) Hijazi, Mai M.
A cell immunoblot technique originally designed for the study of prolactin secretion by rat pituitary cells has been modified and evaluated for the study of relaxin and prolactin accumulation and secretion from individual human decidual cells in vitro. Prolactin has been studied extensively in the human decidua, however nothing is known about the regulation of relaxin secretion. Macrophages were shown to make up 25% and chorionic cytotrophoblasts 10% of the cells in the decidual cell preparation. The decidual cells analyzed were selected by size and absence of immunostaining with macrophage and cytotrophoblast cell markers. Relaxin and prolactin intracellular accumulation and secretion were detected immunocytochemically as intracellular and extracellular staining respectively and were quantitated with an IBAS Kontron image analysis system. Relaxin secretion was detected after 15 min of incubation and was unaffected by cycloheximide suggesting release of preformed hormone. Prolactin on the other hand was only detected intracellularly up to 18 h and this was decreased by cycloheximide suggesting new production synthesis. Relaxin intracellular accumulation and secretion were significantly increased when the cells were incubated with added porcine relaxin, H2 synthetic human relaxin and Hl recombinant human relaxin. Porcine relaxin was slightly more potent than human H2 relaxin, which was more potent than the Hl synthetic peptide in increasing its own synthesis and secretion in vitro. Human and porcine insulins also significantly increased relaxin intracellular and extracellular staining. Preliminary results of added IGF-l and EGF showed stimulatory effects on relaxin intracellular and extracellular staining, but these results were not dose-dependent and are therefore questionable. Exogenous prolactin had both stimulatory and inhibitory effects on relaxin accumulation and secretion, and caused a significant increase in prolactin accumulation without affecting its secretion. The results suggest that relaxin and prolactin may be autocrine hormones in the human decidua, and the effects of relaxin treatment provide indirect evidence for the presence of relaxin receptors on the decidual cells. Preliminary results of treatment with insulin, IGF-l and EGF also suggest that these hormones may act as paracrine regulators of decidual relaxin synthesis and secretion.
Responses of water and salt regulating hormones during acute cold exposure in the rat
(University of Hawaii at Manoa, 1992) Dice, Margaret S.
Soon after exposure to cold, humans and some animals experience a dilute diuresis, which is often accompanied by a natriuresis. Plasma vasopressin has been reported to decrease, possibly due to a central shunting of blood from peripheral vasoconstriction, and subsequent activation of the "Gauer-Henry reflex". The sodium regulating hormones atrial natriuretic factor (ANF), and the renin-aldosterone system have not been measured acutely in the cold. The present study used the conscious, chronically instrumented rat to assess plasma vasopressin, aldosterone, renin, ANF, and urinary vasopressin during acute cold exposures of 1 hour at 13° C., or time control at 26° C.. Urine flow, osmolality, electrolyte excretion rates, and creatinine, osmotic, and free water clearances were measured at 10 minute intervals. Hematocrit, plasma electrolytes and osmolality, and all hormones were obtained using a donor replacement protocol at baseline, at 20, and 60 minutes of cold exposure, and at 1 hour recovery. Rectal temperature, heart rate, and mean arterial blood pressure were monitored, and to evaluate the degree of cold-induced thoracic engorgement, central venous pressure was measured in one series of experiments. In all series of experiments, urine flow increased to double or more baseline values by 20 minutes of cold exposure (p < .05). By 60 minutes, in the cold, however, flow had returned toward baseline, and was different neither from baseline nor from time control. The free water component of the diuresis followed the same pattern, while urinary osmolality decreased biphasically as well. Osmotic clearance significantly increased in all series, and creatinine clearance was unchanged. Plasma vasopressin was significantly reduced compared to baseline at 20 minutes of cold exposure in all three series in which it was measured. Values had returned to baseline levels by 60 minutes in the cold. Mean arterial blood pressure and heart rate increased significantly in the cold (p < .01), while all but one experimental series showed no change in plasma osmolality, and in no series was there a change in rectal temperature. Mean central venous pressure was unaffected by cold exposure, although systolic and pulsatile central venous pressure increased. Cold was without effect on sodium excretion, with both control and cold-exposed groups significantly increasing their rate of excretion. Similarly, there was no change in plasma ANF, although both renin and aldosterone increased progressively during cold exposure. These results suggest that there is no consistent natriuresis in the rat during acute cold exposure, and that an increase in arterial blood pressure may be the driving force behind the observed reductions in plasma vasopressin.
Effects of electromagnetic fields and temperature on avian embryonic growth and oxygen consumption
(University of Hawaii at Manoa, 1992) Zhang, Qinggen
Domestic fowl embryonic growth, oxygen consumption, body dimensions and organ (including pectoral and leg muscles) dry/wet mass, heart rate, respiratory rate and growth abnormalities were studied at altered incubation temperatures (36 °C,40 °C) and after exposure to 2.0, 1.0 and 0.5 gauss (G) electromagnetic fields (EMF), from the seventh day of incubation to hatching. Embryonic organ growth was promoted when incubation temperature was increased from 38°C (control) to 40 °C, but organ growth was significantly retarded when incubation temperature was decreased from 38°C to 36 °C. Evidence was obtained that some tissues (eyeballs and heart) were "spared" the reduction in growth at 36°C, while the lungs, eyeballs and pectoral muscles were spared the accelerated growth at 40 °C. The maturity of the organs (as assessed by their dry/wet mass ratios) was, like their growth, less at 36°C than at 38 °c and this was particularly evident in leg muscle and liver. Organ maturity was enhanced at 40°C especially in the pectoral muscles and stomach. The hatchability of eggs incubated at 36°C was impaired. Embryonic growth and oxygen consumption were increased after exposure to a 2.0 G EMF but inhibited in the 1.0 G EMF group. There were no significant biological effects of 0.5 G EMF on embryonic growth and oxygen consumption. Deformities were found in the 2.0 G and 1.0 G EMF groups but only in the 2.0 G group did reach a statistically significant level. There were no deformities in the 0.5 G EMF group or any of the control groups. The heart and lungs were spared the enhanced overall growth induced by exposure to a 2 G EMF while the intestine was spared the repression of growth at an EMF of I G. Enhanced organ growth was associated with increased tissue maturity, particularly in pectoral muscle and the intestine. The effects of a 1 G EMF on organ maturity were small but, paradoxically, lung maturity increased. A number of deformities was noted in embryos exposed to 2 G EMF. Incubation at 40°C and exposure to a 2 G EMF both increased embryonic growth while incubation at 36°C and exposure to 1 G EMF both repressed growth, overall. However, there were few similarities in the specific effects of the two growth-promoting/ repressing agents on organ growth and maturity. A major difference between temperature ,and EMF was that they exerted their effects at different stages of embryonic life. No significant effects of either temperature or EMF were observed on heart rates, respiratory rates or tissue histology.
Changes in hormone excretion in swimmers over the course of a training season
(University of Hawaii at Manoa, 1991) Hale, David
The purpose of this study is to investigate the change in catecholamine levels over the course of a training season in collegiate swimmers. Swimmers were chosen because there are no reports in the literature that look at the response to stress in actively training swimmers. Additionally, there are very few studies which use athletes trained at the intensity of collegiate swimmers (27, 64, 156). Thus, one of the first requirements of the study was to obtain data on collegiate swimmers training at elite levels. The study was designed to determine the long term changes in hormone secretion patterns when the intensity of training was continually increased. There are no reports of studies on athletes training for more than four months duration (287). Since most elite athletes train for much longer periods of time than four months, the first objective was to develop a research protocol that would result in information on catecholamine production over an extended period of time. A second objective was to test for a relationship between a simple psychological measure and the results obtained from physiological measurements. Since there are no reports about the psychological changes in elite athletes during a training season, a third objective was to determine if there was any correlation between psychological and physiological changes. A fourth objective was to evaluate whether a testing day could be broken into time periods and then assess if there was a particular time period of the day when there was more or less change due to stress. Although a few reports have described the variation in secretion in sedentary subjects with time of day (86, 104,183), none have looked at this variation in elite athletes. A fifth objective was to determine what variable or variables correlated with hormone secretion. Was it distance trained, psychological stress, time of day, or some other factor? Again, no one has reported attempting to determine the relationship of catecholamines to other variables in elite athletes. The last objective of this study was to determine whether any observed changes in catecholamine output were due to changes in production or to changes in metabolism. By measuring the metabolites of norepinephrine and epinephrine, it was anticipated that the factors responsible for changes in hormone excretion could be determined. Thus. this research sought to test three main hypotheses. First: there is a change in catecholamine production in swimmers throughout the training season. Second: this change could be correlated to changes in psychological stress evaluations and to the amount of distance trained. Finally: the change in catecholamine production could be directly correlated to a change in catecholamine metabolite production.
Sodium channel activation mechanisms: insights from deuterium oxide and delta-9-tetrahydrocannabinol substitution
(University of Hawaii at Manoa, 1990) Alicata, Daniel Andrew
Schauf and Bullock (1979, 1982) demonstrated that solvent substitution with deuterium oxide (D2O) significantly affects both sodium channel activation and inactivation kinetics without corresponding changes in gating current or tail current rates. They concluded, (a) no significant component of gating current derives from the final channel opening step and, (b) channels must deactivate (during tail currents) by a different pathway from that used in channel opening. By contrast, Oxford (1981) found in squid axons that, when a depolarizing pulse is interrupted by a brief return to holding potential, subsequent reactivation is very rapid and shows almost monoexponential kinetics. Increasing the interpulse interval resulted in secondary activation rate returning towards control, sigmoid kinetics. He concluded that channels open and close via the same pathway. I have repeated both sets of observations, confirming the results obtained in both previous studies, despite the apparently contradictory conclusions reached by these authors. However, I find that secondary activation following a brief interpulse interval is insensitive to D20, although reactivation following longer interpulse intervals returns towards a D20-sensitivity similar to that of primary activation. I conclude that D20sensitive primary activation and D20-insensitive tail current deactivation involve separate pathways. However, D20-insensitive secondary activation involves reversal of the D20-insensitive deactivation step. Strichartz et al. (1978) were the first to investigate the effects of delta-9tetrahydrocannabinol (THC) on sodium channel conductance mechanisms under voltage-clamp conditions. The authors reported that THC modified channel conductance by slowing the activation kinetics of INa and suppressing ionic conductance (gNa) in a voltage-dependent manner. They also noted that channel inactivation processes were not affected by THC action. The authors concluded that the lengthening of !p and the shift in the voltage-dependence of peak gNa are both related to the relative kinetics of sodium activation and inactivation, and since inactivation was unaffected by THC, alterations of activation alone account for these observed changes. I have repeated the above observations, but I can confirm only one of the three results obtained in the previous studies. I find that THC affects both activation and inactivation kinetics. However, I find that the normalized F(Vm) curves are almost identical indicating no significant shift in surface charge following THC treatment.

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