Normal Hydration Research Articles

L-Cystine-di-beta-naphthylamidase activity in plasma of the snake Bothrops jararaca after chronic challenges of water balance

Plasma protein, osmolality and l-cystine-di-beta-naphthylamidase activity were measured in Bothrops jararaca snakes submitted to normal hydration, water deprivation, water loading, salt loading or argvasotocin injections. Protein and osmolality were similar for male and female snakes in all treatments. Protein content was similar in all treatments, indicating the ability of the animals to maintain fluid balance between the vascular and extravascular compartment under osmotic challenges. Osmolality was increased in water-deprived and salt-loaded and was decreased in water-loaded animals compared with normally hydrated or argvasotocin-injected snakes. Enzymatic activity differed between males and females and was higher in salt-loaded females and in arg-vasotocin-injected females and males than in water-loaded snakes. A positive linear regression between osmolality and l-cystine-di-beta-naphthylamidase was obtained for female snakes (correlation coefficient = 0.6162, P < 0.01). The data show a role of arg-vasotocin in the consistent relationship between water balance and this sex-related aminopeptidase activity.

Measurement of surgically induced corneal deformations using three-dimensional confocal microscopy.

The goal of this study was to develop and apply a new set of experimental techniques for measuring the local deformations induced by partial-thickness corneal incisions in situ. Eight adult cat eyes were enucleated and cannulated, with corneal viability maintained as close to in vivo conditions as possible and intraocular pressure (IOP) carefully controlled. Experimental measurements were made pre/post radial keratotomy (RK) surgery in situ at IOPs of 15, 30, and 45 mm Hg. Incision depth and cross-sectional profiles were measured at the midpoint of selected incisions using three-dimensional (3-D) tandem scanning confocal microscopy (TSCM); central corneal curvature was estimated using a commercial corneal topographical analysis system, and corneal thickness was assessed by both 3-D TSCM and ultrasonic pachymetry. Corneas were then processed for light microscopy and incision depth was measured histologically. Finite element models were developed for comparison with the experimental measurements. There was no significant change in central corneal thickness (-5.3 +/- 3.9%, n = 8) over the course of the experiments, demonstrating that normal endothelial cell function and normal stromal hydration was maintained. The in situ TSCM incision depth measurements were significantly correlated with the histological measurements (slope = 0.95, R = 0.854, p < 0.01, n = 13 incisions). Measured incision gape at the top (anterior) of the stroma was 64.9 +/- 13.4, 87.3 +/- 12.6, and 108.7 +/- 14 microns at IOPs of 15, 30, and 45 mm Hg, respectively. The 3-D incision profiles were nonlinear in shape; comparison with the finite element models suggests that the shape of the wound profile may provide unique information regarding the shear stiffness of the cornea. Overall, the data suggest that TSCM measurements of the cross-sectional profile of the incisions immediately after RK under controlled in situ conditions provide important data regarding the mechanical behavior of the cornea after refractive surgery. These data should provide the foundation for future studies into the relationships between local tissue mechanics and corneal wound healing.

Calcium Hydroxide Formation in Cement-Solidified Industrial Wastes

Differential thermal analysis (DTA) and X-ray diffraction (XRD) were used to compare the formation of calcium hydroxide (Ca(OH)2) in cement solidified wastes hydrated for different times. Both techniques confirm a decrease in the relative amount of Ca(OH)2 and an increase in unreacted cement clinker phases in samples containing three different commercially produced industrial wastes. All three wastes induce significant changes to normal cement hydration reactions which increase with increasing waste addition. When metal leaching has been assessed using the TCLP test, the concentration of metals present in leachates are not significantly affected by the amount of waste present in the solidified product. This demonstrates that acceptable results from single extraction batch leach tests such as the TCLP test may not adequately indicate the quality of solidified wastes.

Clinical Indicators Associated with Unintentional Weight loss and Pressure Ulcers in Elderly Residents of Nursing Facilities

Objective To monitor adults older than 65 years living in nursing facilities and who experience unintentional weight loss of more than 10% of actual body weight in 6 months or more than 5% in 1 month or who have stage II, III, or IV pressure ulcers.Subjects We reviewed 290 medical records for unintentional weight loss and 265 for pressure ulcers.Design Two data-collecting instruments were used: one for pressure ulcers and one for unintentional weight loss. Indicators for each instrument were selected to monitor clinical conditions that tend to be problem-prone areas for these two populations.Statistical analysis Descriptive statistics were used to calculate the frequency of each indicator for each population.Results Of the 24 indicators for unintentional weight loss, the 6 indicators present most often, in descending order, were reduced functional ability, intake of 50% or less of food served for the past 3 consecutive days, chewing problems, serum albumin level less than 35 g/L with normal hydration status, cholesterol level less than 4.1 mmol/L, and refusal of 50% or more of food replacement for the past 7 days. For the residents with pressure ulcers, the indicator present most often was scrum albumin level less than 35 g/L with normal hydration status. The three highest intervention indicators were receives 1.2 g protein per kilogram of actual body weight, receives 120 mg or more of vitamin C daily, and receives 112 times the energy required based on goal body weight. When serum albumin level was documented in the medical record, it was a valid indicator for both diagnoses.Conclusions Inappropriate dietary intake, disease, and disability place residents in nursing facilities at risk for malnutrition. Thus, it is important to obtain laboratory values when assessing elderly residents and determining their nutritional status. J Am Diet Assoc. 1995; 95:984-992.

Fluid needs in hot and cold environments.

Of all the physiological perturbations that can cause early fatigue during exercise, dehydration is arguably the most important, if only because the consequences of dehydration are potentially life threatening. The rise in body temperature that normally accompanies exercise stimulates an increase in blood flow to the skin and the onset of sweating. Normal hydration is protective of these thermoregulatory responses, whereas even a slight amount of dehydration results in measurable declines in cardiovascular and thermoregulatory function. Mild to severe dehydration commonly occurs among athletes, even when fluid is readily available. This voluntary dehydration compromises physiological function, impairs exercise performance, and increases the risk of heat illness. Recent research illustrates that maintaining normal hydration (or close to it) during exercise maintains cardiovascular and thermoregulatory responses and improves exercise performance. Consequently, it is in the athlete's best interest to adopt fluid-replacement practices that promote fluid intake in proportion to sweat loss.

Characterization of chromium doped tricalcium silicate using SEM/EDS, XRD and FTIR

The containment of chromium in tricalcium silicate (C 3S 1 1 Cement Notations: C = CaO; S = SiO 2; H = H 2O; CH = Ca(OH) 2. ) has been investigated. Tricalcium silicate is a major component in ordinary Portland cement (OPC), and chromium compounds used as dopants simulate chromium wastes that might be stabilized in a cement matrix. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to probe the distribution of chromium in the stabilized waste form and also to identify the microstructural changes in the normal hydration products of C 3S accompanying the addition of chromium as Cr(III) and Cr(VI). X-ray diffraction (XRD) was used to monitor the hydration reaction of C 3S and formation of crystalline calcium hydroxide (CH). The effect of chromium addition on the condensation of the orthosilicate units in C 3S was followed with Fourier transform infrared spectroscopy (FTIR). Standard acetic acid leaching tests were carried out to evaluate the mobility of chromium in the Cr(III) C 3S and Cr(VI) C 3S systems. Probable mechanisms of chromium containment in the amorphous calcium silicate hydrate (C-S-H) phase are discussed.

KCl cotransport activity in light versus dense transferrin receptor-positive sickle reticulocytes.

A subset of sickle cells becomes K(+)-depleted and dehydrated before or soon after leaving the bone marrow. These young cells may be identified in blood as transferrin receptor-positive (TfR+) dense reticulocytes. KCl cotransport, which is normally active in young erythroid cells with a maximum at pH 6.8, is a candidate pathway for K+ depletion of sickle reticulocytes. In this investigation, KCl cotransport activity was evaluated in young, TfR+ cells which had become dense in vivo and in age-matched cells which had retained normal hydration. Sickle erythrocytes were first separated into three primary density fractions, with care taken to preserve the in vivo hydration state. After normalization of intracellular hemoglobin concentration with nystatin, the cells were incubated at 37 degrees C for 20 min at pH 6.8 and 7.4. Before and after incubation, each primary fraction was separated into four secondary density fractions. The percentage of TfR+ cells in each secondary fraction was measured and a density distribution for TfR+ cells was determined for each primary fraction before and after incubation. The density shift during incubation was a measure of KCl cotransport. TfR+ cells from the denser primary fractions II and III had significantly more density shift than TfR+ cells from the light fraction I. Although the shifts were larger at low pH, differences between primary fractions were also observed at pH 7.4. These data indicate that the cells which become dense quickly in vivo have more KCl cotransport activity than those which remain light in vivo, and support this pathway as a primary mechanism for dehydration of young sickle cells.

Determination of the relation between alterations of total body water and thoracic fluid content during ultrafiltration by bioelectrical impedance analysis

Total body impedance (TBI) is used to monitor alterations in total body water (TBW), e.g. during haemodialysis. However, 80% of the TBI signal is due to the resistance in extremities. Therefore TBI measurements give little information about alterations in thoracic fluid content (TF). Measuring both total body impedance and thoracic impedance (THI) can be a useful method to monitor TBW and TF changes during haemodialysis. In this study TBI and THI measurements were performed during 30 dialysis sessions and also in one group of 24 control subjects with normal tissue hydration. During haemodialysis TBI and THI significantly increased, demonstrating a decrease of TBW and TF. The ratio THI/TBI did not differ significantly during haemodialysis, indicating a similar effect of ultrafiltration on TBW and TF. The finding that TF decreased during haemodialysis was rather surprising, whereas pulmonary oedema is not an evident clinical problem in patients on maintenance haemodialysis treatment. THI measurements after dialysis proved to be significantly higher in comparison to the control subjects. This finding supports the hypothesis that the decrease in TF during dialysis is partly due to the sudden ultrafiltration-induced hypovolaemia leading to a fall in thoracic blood volume. UF volume, ultrafiltration volume; TBI, total body impedance; THI, thorax impedance; TBW, total body water; TF, thoracic fluid.

Bivariate normal values of the bioelectrical impedance vector in adult and elderly populations

Accurate estimates of total body water and fat-free mass can be achieved by using equations with bioelectrical resistance and height (H) (1-3). Measurements of whole-body resistance (R) and reactance (Xc) at multiple frequencies in the range of 5-1000 kHz did not provide any significant improvement over measurements made at 50 kHz for the estimation of extracellular and total body water when using any combination of R and Xc (4). In patients with fluid overloading, equations validated in a healthy population produce biased estimates of body compartment volumes. If the normal range of the impedance vector were known in the reference population, the traditional prediction formulas could be applied with confidence to subjects lying in the reference interval. Following this rationale and assuming the bivariate normal distribution (5) of the vector components R/H and Xc/H, we recently calculated the bivariate, 75% and 95%, sex-specific tolerance limits of the normal impedance vector (ie, the ellipses of the healthy population, within which the vector of the individual subject falls with a probability of 75% and 95%, respectively) and we identified a bioelectrical impedance threshold for apparent edema on the lower pole of the sexspecific 75% tolerance ellipse (6). The performance of the threshold in detecting apparent edema was operating with 97% sensitivity and 81% specificity. Moreover, the frequency distributions of vectors falling out of the tolerance ellipses did not significantly differ when comparing body segments with the whole body, thus excluding operative advantages of segmental measurements in renal patients with fluid overloading (7). However, since the estimation of a normal range may be critically dependent on the sample size of the reference population, we extended the study to a population of 726 healthy subjects, 354 males [median age 48 y, range 15-85 y, body mass index 17-31 (kg/rn2)] and 372 females [median age 50 y, range 15-85 y, body mass index 16-31 (kg/m2)] living in northern Italy (Padua, Venice, and Florence). All measurements [standard tetrapolar method (1-4)] were made in the three centers by using three impedance plethysmographs of the same model (BIA-109; RJL/Akern Systems, Detroit), which emitted 800 p.A and a 50 kHz alternating sinusoidal current. The center effect (ie, the sum of operator and instrument variabilities), expressed as a CV, was 3% for R and 8% for Xc. In males, RIB (1 ± SD) was 298.6 ± 43.2 fl/rn; Xc/H was 30.8 ± 7.2 fI/m. R/H and Xc/H were significantly correlated in males (r = 0.47, P < 0.001). In females, R/H (1 ± SD) was 371.9 ± 49.0 f1/m; Xc/H was 34.4 ± 7.7 fl/rn. R/H and Xc/H were also significantly correlated in females (r = 0.41, P < 0.001). The 95% confidence ellipses (see Figure 1) of the average impedance vector did not overlap, indicating a significantly longer vector in females, which was also found in a previous pilot study with 86 healthy subjects (6). Of the 726 healthy subjects, 95 males and 91 females were aged 65-85 y, with body mass indexes of 24 (kg/rn2, range 18-30) and 25 (kg/rn2, range 16-31), respectively. Neither R/H nor Xc/H was significantly correlated with age either below or above 65 y (-0.16 < r < 0.13 in males, and -0.10 < r < 0.02 in females). Therefore, we did not plot the set of overlapping tolerance ellipses by age classes. In Figure 1, three sex-specific tolerance ellipses are drawn corresponding to the median, 75th, and 95th percentiles of the impedance vector distribution calculated from our healthy population. Interestingly, despite equal slopes, the ellipses were larger in females, which is consistent with a greater variability in female body composition (6). However, the threshold for apparent edema, ie, the lower pole of the 75% tolerance ellipse, reached similar Xc/H values in males and females, as was found in the pilot study (6). In practice, plotting direct R/H and Xc/H measurements on the population percentile distributions (ie, on the tolerance ellipses) allows one to decide whether a subject has maintained normal hydration. If estimates of volume and mass of body compartments are of interest, the traditional prediction formulas (1-3) can be safely applied with the probability level indicated by the ellipse percentile. Further studies are necessary to interpret the longer vectors falling out of the upper poles, as in dehydration, and the vectors of normal length but with extreme phase angles (ie, beyond the left or right ends of the small axes of the tolerance ellipses), as expected in extremes of lean body mass (eg, in athletes or in anorexia or wasting conditions) (6). Data from renal patients and from the literature, plotted as “RXc path graph” over the tolerance ellipses support a simple operative rule in the bedside interpretation of bioelectrical impedance analysis measurements: whereas a progressive shortening and down-sloping of the impedance vector over successive measurements indicates

Facial selectivity in the hydroboration of androst-4-enes

In the absence of an allylic hydroxy group, the stereochemistry of hydroboration of an androst-4-ene is determined by the presence and stereochemistry of the C-10 methyl group. Allylic hydroxy groups at C-3 direct the hydroboration/oxidation to the anti-face. In the case of the 3α-alcohol, this effect is in opposition to the normal hydration from the α-face of the steroid and leads to the 4β-alcohol. The stereochemistry of 4β,17β-diacetoxy-19-nor-5β-androstane was established by X-ray crystallography.

A Calorimetric Study of the Effect of Organic Compounds On the Initial Behaviour of Cement-Based Solidified Wastes

Seven organic compounds commonly found in toxic wastes were added to ordinary Portland cement (OPC) at varying concentrations. The influence of these organics, which display a variety of chemical characteristics, on the heat of hydration, setting, strength development and microstructure were observed. Most organics influenced early hydration by retardation or acceleration but mature samples displayed a similar phase composition to the OPC control. Microstructural observation of organic-containing OPC indicated that subtle spatial variations in the distribution of hydration phases and topographic features existed despite the absence of significant interference with normal hydration reactions.

Tamoxifen blocks chloride channels. A possible mechanism for cataract formation.

Tamoxifen is an antiestrogen frequently used in the treatment of breast cancer and is currently being assessed as a prophylactic for those at high risk of developing tumors. We have found that tamoxifen and its derivatives are high-affinity blockers of specific chloride channels. This blockade appears to be independent of the interaction of tamoxifen with the estrogen receptor and therefore reflects an alternative cellular target. One of the clinical side effects of tamoxifen is impaired vision and cataract. Chloride channels in the lens of the eye were shown to be essential for maintaining normal lens hydration and transmittance. These channels were blocked by tamoxifen and, in organ culture, tamoxifen led to lens opacity associated with cataracts at clinically relevant concentrations. These data suggest a molecular mechanism by which tamoxifen can cause cataract formation and have implications for the clinical use of tamoxifen and related antiestrogens.

Age-Dependent Changes of Hyaluronan in Human Skin

Hyaluronan is a major component of the extracellular matrix of skin. The large volume of water of hydration associated with hyaluronan may be a mechanism for maintaining the normal hydration of skin. As such, decreasing levels of hyaluronan deposition might underlie the changes associated with the aging process. To test this hypothesis, hyaluronan levels were determined in extracts of skin obtained at autopsy from individuals of different ages. However, no significant differences in hyaluronan concentrations were found. The distribution of hyaluronan polymer sizes in various extracts did not change as a function of age as measured by size exclusion chromatography. However, major differences in hyaluronan extractability did occur as a function of age. Sequential extraction was performed utilizing 1) 0.1% Triton X-100, 2) 4 M guanidine-HCl, and 3) papain digestion, to release species of hyaluronan progressively more tightly associated with tissue. With advancing age, hyaluronan polymers became progressively more tissue associated. The proportion of hyaluronan released after papain digestion increased from 7% of the total in fetal to 23% of the total in senescent skin. Finally, histolocalization of hyaluronan was examined in full-thickness sections of human skin of different ages. Major differences in compartmentalization were found. We conclude that neither the concentration nor polymer size of hyaluronan changes as a function of age. However, enhanced association with tissue occurs, presumably through hyaluronan-binding proteins and alterations in the histolocalization of hyaluronan. Such observations may underlie some of the changes in human skin that occur with aging.

Effect of hydration on lung interstitial permeability response to albumin and hyaluronidase

Previous studies showed that the flows of albumin and hyaluronidase solutions increased relative to that of saline in isolated segments of rabbit lung interstitium (Lai-Fook et al. J. Appl. Physiol. 67:606-613, 1989). We questioned whether these effects were hydration dependent. In interstitial segments the flows of lactated Ringer, albumin (5 and 10 g/dl), and hyaluronidase (0.02%) solutions were measured at mean interstitial pressures (Pm) between -5 and 15 cmH2O with a constant driving pressure of 5 cmH2O. The albumin-to-Ringer flow ratio increased monotonically from near the viscosity-dependent value (0.75-0.77) at -5 cmH2O Pm to values of 1.6-2.1 at 15 cmH2O Pm. A similar behavior was observed for the flow of the hyaluronidase solution relative to that of Ringer solution. The increased permeability response to albumin was independent of the albumin concentration used. By contrast, the response to hyaluronidase was lower when the interstitium was perfused with the higher concentration albumin solution (10 g/dl) before the flow of hyaluronidase, indicating an inhibitory effect of albumin on the hyaluronidase response. Estimates of interstitial hydration from Pm indicated an increased interstitial permeability (conductivity) to the flows of albumin and hyaluronidase solutions only after interstitial volume had doubled, whereas interstitial permeability was viscosity dependent at normal interstitial hydration.

Effect of initial water curing on the hydration of cements containing natural pozzolan

This paper deals with the effect of initial curing conditions on the hydration process of Portland pozzolan cements. Experiments were performed on pastes made with Canadian Standards Association (CSA) Type 10 (ASTM Type I) Portland cement (PC) and Portland pozzolan cement (PPC) containing 30% natural pozzolan by mass. PC pastes are more sensitive than PPC pastes to the period of initial water curing because the hydration of PC occurs more quickly than does the pozzolanic reaction in PPC pastes. The hydration of Portland cement and the pozzolanic reaction continue after specimens are removed to a dry environment (relative humidity ≈ 20%). The presence of natural pozzolans retards the normal hydration of PC before an age of 1 day but accelerates it after 1 day. For the tests reported here, an excellent correlation exists between strength and the quantity of “hydrate” water. The measurement of pore structure shows that the measurable total pore volume is significantly decreased for specimens that are water-cured and then dried, compared with those that are water-cured only. The period of initial water curing does not have a significant effect on total pore volume at 28 days (measured by Hg porosimetry), but does affect the pore size distribution. Examination of strength is not a good indicator of the effect of initial water curing.

COMPARATIVE EFFECT OF UVA AND UVB ON CULTURED RABBIT LENS

Effects on lens physiology of UVB and UVA used separately and sequentially were investigated using 4 week old rabbit lenses in organ culture. Narrowband UVB at 0.3 J/cm2 = joules/lens (1 h exposure) has little effect on sodium and calcium concentrations in the lens interior or transparency of lenses subsequently cultured for 20 h after a 1 h exposure. With an incident energy of 3 J/cm2 of broadband UVB (295-330 nm), lenses become opaque and slightly swollen with significant ion imbalances during culture over a 1 day period. In contrast, lenses exposed to approximately 6-24 J/cm2 of UVA (330-400 nm) remain transparent after 1 day of culture. Extended culture up to 4 days reveals no signs of opacification. Ion homeostasis and normal lens hydration are also maintained in UVA-irradiated lenses. The presence of 95% oxygen during UVA irradiation is also without effect. Broadband UVA irradiation is damaging, however, if lenses are first exposed to subthreshold doses of narrowband UVB (307 +/- 5 nm) irradiation, viz. 0.3 J/cm2. Thus, sequential UVB/UVA irradiation at subthreshold doses causes impaired active cation transport and accumulation of sodium and calcium accompanying lens opacification.

Effect of water restriction on energy and water balance and osmoregulation of the fruit bat Rousettus aegyptiacus.

The energy budget, water balance and osmoregulation of the fruit bat, Rousettus aegyptiacus, were studied during normal hydration and during water restriction (oven-dried apple diet). The water input and output were balanced during both normal hydration and water restriction. The kidney of the fruit bat is well adapted to handle the water load from its fruit diet by excreting large volumes (14% of the body mass per day) of dilute urine (113 +/- 25 mosmol.kg H2O-1) as well as reducing urine volume (-95%) and increasing urine osmotic concentration (555 +/- 280 mosmol.kg H2O-1) during water restriction. The haematocrit, plasma haemoglobin and total protein concentrations did not increase during water restriction and heat exposure, suggesting the conservation of plasma volume. Gross energy intake was not affected by water restriction. However, digested energy intake and digestibility were significantly reduced. The effective regulation of energy and water budgets during water restriction suggests that the fruit bat can cope with seasonal climatic changes and with variable fruit supply during various seasons.

Single-dose intravenous therapy with pamidronate for the treatment of hypercalcemia of malignancy: Comparison of 30-, 60-, and 90-mg dosages

purpose: To determine the efficacy, dose-response relationship, and safety of 30, 60, and 90 mg of a single intravenous dose of an aminobisphosphonate, pamidronate (APD), for the treatment of moderate to severe hypercalcemia of malignancy. patients and methods: Patients with histologically proven cancer and a corrected serum calcium level of at least 12.0 mg/dL after 48 hours of normal saline hydration were enrolled in a double-blind, multicenter, randomized clinical trial. Pamidronate in 30-, 60-, or 90-mg doses was administered as a single 24-hour infusion. Serum calcium corrected for albumin, urine hydroxyproline, and calcium excretion, and serum parathyroid hormone (PTH) (1–84) were determined before and after pamidronate therapy. results: Thirty-two men and 18 women entered the study. A dose-response relationship for normalization of corrected serum calcium was seen after pamidronate administration. Corrected serum calcium normalized in 40% of patients who received 30 mg, in 61% of patients who received 60 mg, and in 100% of patients who received 90 mg of pamidronate. The decline in the serum calcium level was associated with decreased osteoclastic skeletal resorption evidenced by a decrease in urine calcium and hydroxyproline excretion. Among those with a normalized corrected serum calcium level, the mean (median) duration of normalization of the corrected serum calcium value was 9.2 (4), 13.3 (5), and 10.8 (6) days in the 30-, 60-, and 90-mg treatment groups, respectively. The response of hypercalcemia to pamidronate was not significantly influenced by the presence of skeletal metastases. PTH 1–84, suppressed in patients on entry into this study, increased to a greater extent in those patients with osteolytic skeletal metastases compared with those with humoral hypercalcemia of malignancy. Clinical improvement, including improved mental status and decreased anorexia, accompanied the decline in the corrected serum calcium level in all three treatment groups. Side effects included low-grade fever, asymptomatic hypocalcemia, hypomagnesemia, and hypophosphatemia. conclusions: A single-dose infusion of 60 to 90 mg of pamidronate was highly effective and well tolerated and normalized corrected serum calcium in nearly all patients (61% to 100%) with hypercalcemia of malignancy.

Alterations in erythrocyte chloride content accompanying the changes in erythrocyte hydration and potassium content in normal human pregnancy: a comparison with pregnancy induced hypertension.

To determine whether the change in erythrocyte potassium content in normal human pregnancy is accompanied by a similar change in erythrocyte chloride content. To assess erythrocyte hydration and potassium and chloride content in pregnancies complicated by proteinuric pregnancy induced hypertension. A serial study during and after normal pregnancy. A comparative study during and after pregnancies complicated by proteinuric pregnancy induced hypertension (PIH). Erythrocyte hydration, total osmoles, potassium and chloride and plasma osmolality were determined. University teaching hospital, UK. Twenty-eight women studied at 14, 28 and 36 weeks of normal pregnancy and ten women with PIH studied during the third trimester of pregnancy. All women were reinvestigated 20 weeks after delivery. The fall of erythrocyte potassium early in normal pregnancy (277.4 vs 265.2 mmol/kg; P < 0.02) and its rise between 28 and 36 weeks (272.3 vs 288.0 mmol/kg; P < 0.005) were accompanied by similar changes in erythrocyte chloride content (151.9 vs 131.1 mmol/kg; P < 0.001 and 129.4 vs 141.3 mmol/kg; P < 0.001, respectively). Plasma osmolality in PIH was raised above that normal in pregnancy (287.2 vs 283.0 mosm/kg; P < 0.005). In PIH, compared to normal pregnancy, erythrocyte hydration (2.00 vs 1.89 l/kg dry weight cells), total osmoles (573.0 vs 534.2 mosm/kg), potassium (303.0 vs 288.0 mmol/kg) and chloride (154.9 vs 141.3 mmol/kg) were greater. These findings further support the hypothesis that changes in plasma osmolality in pregnancy are secondary to alterations in cell osmoles and serve to limit changes in cell hydration. Erythrocyte composition and plasma osmolality are altered in PIH.

Effect of water restriction on temperature regulation of the fruit-bat Rousettus aegyptiacus

1. 1. The thermoregulatory responses of the fruit-bat, Rousettus aegyptiacus, the only fruit-bat out of 32 bat species in Israel, were studied over a wide range of ambient temperature during normal hydration and during water restriction. 2. 2. The thermoneutral zone of the normally-hydrated fruit-bat ranged between 31–36°C. Oxygen consumption in this range averaged 0.95 ± 0.15 ml g −1 h −. 3. 3. Evaporative water loss and respiration frequency during normal hydration incrased as power functions of ambient temperature and were significantly correlated ( P < 0.02). The normally-hydrated, heat exposed fruit-bat effectively regulated its body temperature and dissipated the total metabolic heat production by evaporative cooling. 4. 4. In bats fed on oven-dried apples (water restriction), body mass decreased by 20.72 ± 2.78%. Oxygen consumption between 32–36°C increased significantly and body temperature was relatively high. Evaporative water loss decreased sinificantly, except at 36°C where evaporative water loss was not significantly different from that during normal hydration, suggesting the preference for body temprature regulation at the cost of increased water loss. At this ambient temperature, dry thermal conductance increased significantly compared to normal hydration, facilitating non-evaporative heat loss. 5. 5. We conclude that the Israeli population of Rousettus aegyptiacus is adapted to the relatively warm climate and can cope with a decreased water content in its exclusive fruit diet and effectively regulate its body temperature and metabolic rate.