Behavioural thermoregulation in Daphnia carinata from different depths of a natural water body: influence of environmental oxygen levels and temperature.

The influence of environmental parameters (water temperature and dissolved oxygen content) on the haemoglobin content of a naturally occurring population of Daphnia carinata was studied in a population resident in an intermittently flowing, shallow body of water. It was found that the Hb content of the animals was influenced by a combination of both the water temperature and dissolved oxygen profiles of the water body. In Summer, stratification, as indicated by sampling at three depths, constrained thermoregulatory behaviour; Hb-poor animals from the upper levels of the water column chose a lower temperature in hypoxia than their Hb-rich counterparts from greater depth. In Winter, the water column was mixed and remained moderately hypoxic at all times. Due to the low temperature of the water, Hb-contents in winter were much lower than those found in Summer. Overall, it was found that thermoregulatory behaviour in D. carinata is dependent upon Hb-content, which is strongly influenced by the animals' environment.

Ventilation and metabolism in a large semifossorial marsupial: the effect of graded hypoxia and hypercapnia.

Metabolic and ventilatory variables were measured in a large semifossorial marsupial, the hairy-nosed wombat (Lasiorhinus latifrons, 21.9 kg). In normoxia, the rate of oxygen consumption was 63% of that predicted for a similar-sized marsupial, and the level of ventilation (V(E)) was such that the convective requirement (V(E)/VO2) was similar to other mammals. Exposure to hypercapnia (5% CO(2)) evoked a hyperventilatory response (3.55 x normoxia) that was no different to that observed for epigeal (surface-dwelling) marsupials; the increase in V(E) was primarily achieved with an increase in tidal volume. Exposure to hypoxia (15% to 8% O(2)) resulted in a hyperventilation (principally through an increase in frequency), although the response was blunted (in 8% O(2), 1.85 x normoxia) and only at the severest levels did hypometabolism contribute. The attenuated response to hypoxia in the wombat is presumably a reflection of a semifossorial lifestyle and a tolerance to this respiratory stimulant.

High and low density intracellular water.

The proposal that liquid water consists of microdomains of rapidly-exchanging polymorphs of high and low density is examined for its impact upon roles of water in biology. It is assumed that the two polymorphs persist in solution and adjacent to surfaces and that solutes partition asymmetrically between them. It transpires that chaotropes are solutes which partition preferentially into low density water and displace the water equilibrium toward the high density polymorph. Kosmotropes. both ionic and non-polar, partition into high density water and induce low density water. Displacement of the water equilibrium at constant temperature and pressure has a thermodynamic cost which can be high. This appears to be a dominant factor in folding of proteins and DNA, aggregation of biopolymers and insolubility of non-polar kosmotropes. Cells control both the concentration of proteins and the selection of small solutes to produce an intracellular environment most conducive to co-ordinated enzyme function. Intracellular water has similar microdomains to bulk water, but surfaces and solutes redistribute them. Average properties, as measured by NMR are similar, but local properties on a nm scale may differ widely. Enzymes apparently use these local differences to activate cations for transport, induce movement and for synthesis.

Behavioral thermoregulation in obese and lean Zucker rats in a thermal gradient.

Genetically obese Zucker (Z) rats have been reported to display a body core temperature (Tb) that is consistently below that of their lean littermates. We asked the question whether the lower Tb was a result of deficits in thermoregulation or a downward resetting of the set point for Tb. For a period of 45 consecutive hours, lean and obese Z rats were free to move within a thermal gradient with an ambient temperature (T(a)) range of 15-35 degrees C, while subjected to a 12:12-h light-dark cycle. Tb was measured using a miniature radio transmitter implanted within the peritoneal cavity. Oxygen consumption (VO2) was measured using an open flow technique. Movements and most frequently occupied position in the gradient (preferred T(a)) were recorded using a series of infrared phototransmitters. Obese Z rats were compared with lean Z rats matched for either age (A) or body mass (M). Our results show that obese Z rats have a lower Tb [37.1 +/- 0.1 degrees C (SD) vs. 37.3 +/- 0.1 degrees C, P < 0.001] and a lower VO2 (25.3 +/- 1.9 ml x kg(-1) x h(-1)) than lean controls [33.1 +/- 3.7 (A) and 33.9 +/- 3.9 (M) ml x kg(-1) x h(-1), P < 0.001]. Also, the obese Z rats consistently chose to occupy a cooler T(a) [20.9 +/- 0.6 degrees C vs. 22.7 +/- 0.6 degrees C (A) and 22.5 +/- 0.7 degrees C (M), P < 0.001] in the thermal gradient. This suggests a lower set point for Tb in the obese Z rat, as they refused the option to select a warmer T(a) that might allow them to counteract any thermoregulatory deficiency that could lead to a low Tb. Although all rats followed a definite circadian rhythm for both Tb and VO2, there was no discernible circadian pattern for preferred T(a) in either obese or lean rats. Obese Z rats tended to show a far less definite light-dark activity cycle compared with lean rats.

Urinary pharmacokinetics of the glucuronide and sulfate conjugates of genistein and daidzein.

Consumption of soybean-rich diets is thought to provide significant health benefits such as prevention of cancer, primarily because of the high contents of factors such as the isoflavones genistein and daidzein. Isoflavones circulate and are excreted into the urine mainly as glucuronide and sulfate conjugates. This study was conducted to determine the urinary pharmacokinetics of sulfate and glucuronide conjugates of genistein and daidzein. Twelve volunteers consumed a soy beverage providing 1 and 0.6 mg/kg body weight of genistein and daidzein equivalents, respectively. Urine was collected at various times during the 48 h after soy consumption and was digested with either glucuronidase or sulfatase, and the liberated aglycones were extracted and analyzed by liquid chromatography-mass spectrometry. Urinary isoflavone sulfate levels were determined by two methods: (a) assessment of aglycone after sulfatase hydrolysis (measured); or (b) calculated by subtracting the aglycone + glucuronide levels from the total urinary isoflavone levels. The apparent terminal half-life for daidzein sulfate (3.9+/-0.5 h) that was determined from sulfatase-treated urine was 32% shorter (P < or = 0.02) than that of the calculated daidzein sulfate (5.7+/-0.08 h). A similar trend was obtained for genistein sulfate (4.5+/-0.7 versus 6.8+/-0.1 h). The apparent terminal half-lives for genistein and daidzein glucuronides were 6.0+/-0.4 and 3.8+/-0.4 h, respectively. These data suggest that the measured urinary isoflavone sulfate values provide a better understanding of the pharmacokinetics than the calculated values. Additional studies are needed to determine whether the apparent terminal half-lives can be attributed to elimination or absorption processes.

The influence of haemoglobin on behavioural thermoregulation and oxygen consumption in Daphnia carinata.

When placed in a temperature gradient, most ectotherms have a strict thermal preference that is lowered on exposure to hypoxia. Branchiopods, small aquatic crustaceans, are known to synthesise haemoglobin (Hb) when exposed to hypoxia; hypoxia can occur diurnally and seasonally in ponds. The effect of Hb on behavioural thermoregulation in the branchiopod Daphnia carinata following exposure to both normoxia and hypoxia was examined. Control animals raised in normoxia (Po2=150 mmHg, [Hb]=0.026+/-0.007 mg g dry wt-1) and Hb-rich animals raised in hypoxia (Po2=70 mmHg, [Hb]=0.080+/-0.017 mg g dry wt-1) were placed (N=30) in a tube (length=500 mm, diameter=8 mm) filled with pond water. In the absence of a thermal gradient, control and Hb-rich animals in normoxic water were uniformly distributed along the tube. The presence of a thermal gradient (13 degrees -28 degrees C) elicited clustering at a preferred temperature, T approximately 23 degrees C for both groups. Exposure to hypoxic water in a thermal gradient resulted in a behavioural shift: T approximately 16 degrees C for controls and T approximately 19 degrees C for Hb-rich animals. Measurements of oxygen consumption (V&d2;o2) at fixed temperatures revealed that Hb is associated with a metabolic acclimation to hypoxia.

Hypothesis: hyperstructures regulate bacterial structure and the cell cycle.

A myriad different constituents or elements (genes, proteins, lipids, ions, small molecules etc.) participate in numerous physico-chemical processes to create bacteria that can adapt to their environments to survive, grow and, via the cell cycle, reproduce. We explore the possibility that it is too difficult to explain cell cycle progression in terms of these elements and that an intermediate level of explanation is needed. This level is that of hyperstructures. A hyperstructure is large, has usually one particular function, and contains many elements. Non-equilibrium, or even dissipative, hyperstructures that, for example, assemble to transport and metabolize nutrients may comprise membrane domains of transporters plus cytoplasmic metabolons plus the genes that encode the hyperstructure's enzymes. The processes involved in the putative formation of hyperstructures include: metabolite-induced changes to protein affinities that result in metabolon formation, lipid-organizing forces that result in lateral and transverse asymmetries, post-translational modifications, equilibration of water structures that may alter distributions of other molecules, transertion, ion currents, emission of electromagnetic radiation and long range mechanical vibrations. Equilibrium hyperstructures may also exist such as topological arrays of DNA in the form of cholesteric liquid crystals. We present here the beginning of a picture of the bacterial cell in which hyperstructures form to maximize efficiency and in which the properties of hyperstructures drive the cell cycle.

Preservation of murine embryos in a state of dormancy at 4 degreesC.

With the aim of improving preservation of blood products and organs for transplantation, we designed solutions to induce a state of dormancy in cells and tissues at 4 degreesC. The solutions were devoid of combinations of ions (e.g., K+, Rb+, Cs+, and NH+4 with HCO-3, H2PO-4, and Cl-) that are believed to break down low-density water in the entrance compartments of ion channels, resulting in cyclical open states (normal water) and closed states (low-density water). The total osmolality was always 0.29-0.3 osmol/kgH2O, made up of combinations of a di- or trisaccharide, a compatible solute, sodium sulfate, citrate, or chloride, and 1.75 mM CaCl2. The end point was the ability of murine embryos to progress to hatching in culture after preservation in such a solution at 4 degreesC. Embryos hatched after 5 or 6 days in some preservative solutions compared with 1-3 days in most saline solutions; survival was improved by pretreatment with sodium butyrate.

Measuring the elastic modulus of small tissue samples.

Independent measurements of the elastic modulus (Young's modulus) of tissue are necessary step in turning elasticity imaging into a clinical tool. A system capable of measuring the elastic modulus of small tissue samples was developed. The system tolerates the constraints of biological tissue, such as limited sample size (< or = 1.5 cm3) and imperfections in sample geometry. A known deformation is applied to the tissue sample while simultaneously measuring the resulting force. These measurements are then converted to an elastic modulus, where the conversion uses prior calibration of the system with plastisol samples of known Young's modulus. Accurate measurements have been obtained from 10 to 80 kPa, covering a wide range of tissue modulus values. In addition, the performance of the system was further investigated using finite element analysis. Finally, preliminary elasticity measurements on canine kidney samples are presented and discussed.

High and low density water and resting, active and transformed cells.

Resting and active states of cells are described in terms of the expectation, derived from experiments with aqueous polymers, that they contain two modified forms of water: high density, reactive, fluid water and low density, inert, viscous water. Low density water predominates in a resting cell and is converted to high density water in an active cell. It is proposed that switching from one state to another is an integral part of cellular function. When this ability is lost cells are transformed either to a state of rigor or to a hyperactive state in which they no longer depend upon external signals.

Epidemiology of dermatitis among California farm workers.

To estimate the prevalence of dermatitis and risk factors for skin disease in California farm workers, a cross-sectional survey was conducted among grape, citrus, and tomato workers. The prevalence of contact dermatitis was 2% and lichenified hand dermatitis was 13%. Grape workers were more likely to report rashes in the last 12 months than were tomato workers or citrus workers. Grape workers were more likely to have contact dermatitis and lichenified hand dermatitis than were citrus or tomato workers. Increasing hours per week in agriculture, male sex, and not wearing gloves were associated with more lichenified hand dermatitis. We conclude that skin disease in agricultural workers may be causally associated with crop-specific exposures and lack of protective equipment.

An antipodean perception of the mode of action of glycoprotein hormones.

Continuance of vertebrate species and maintenance of metabolism have an absolute requirement for the glycoprotein hormones of the anterior pituitary gland. It is now firmly accepted that the N-glycans of these and the related placental hormone, chorionic gonadotropin, have essential if undefined roles in their mechanism of action. However, recent investigations by Weisshaar and his colleagues on the oligosaccharides of human luteinizing hormone and chorionic gonadotropin, do not support the generally accepted view of carbohydrates in hormone-receptor interactions and a further concept is proposed that invokes negative charges and changes in structured water.

Donnan membrane equilibrium is not directly applicable to distributions of ions and water in gels or cells.

Equilibration of ions and water with a charged gel does not follow the simple equations of the classical Gibbs-Donnan membrane equilibrium. Partition of ions between the gel and the external solution show specific effects, which require that activity coefficients are different in the two compartments. Highly hydrated ions, such as Na(+) and H(+) are accumulated into the gel water, whereas less highly hydrated ions, such as K(+) and NH(4) (+) accumulate in the external water. This selectivity is the obverse of that found for gels containing low-density, expanded water. Water in a charged gel equilibrated with solutions of MgCl(2) was found to be more dense than bulk water at the same temperature. It is proposed that gels imbibe water to maximize the entropy of the system. Ions and water then equilibrate under those constraints. The chemical potential of water in the two compartments equalizes by an increase in density in the compartment of higher osmolality (the charged gel) and a decrease in density in the compartment of lower osmolality (the external solution). Electrolytes equilibrate so that macroscopic electroneutrality is conserved, and the chemical potential of an electrolyte is the same in each compartment. Because activity coefficients are different in the two compartments this results in asymmetric distributions of ions.Because real gels usually contain both charged and hydrophobic regions of surface, populations of water molecules of different density coexist even in very small pores. This accounts for the common failure to detect this phenomenon experimentally.

Role of water in some biological processes.

The state of intracellular water has been a matter of controversy for a long time for two reasons. First, experiments have often given conflicting results. Second, hitherto, there have been no plausible grounds for assuming that intracellular water should be significantly different from bulk water. A collective behavior of water molecules is suggested here as a thermodynamically inevitable mechanism for generation of appreciable zones of abnormal water. At a highly charged surface, water molecules move together, generating a zone of water perhaps 6 nm thick, which is weakly hydrogen bonded, fluid, and reactive and selectively accumulates small cations, multivalent anions, and hydrophobic solutes. At a hydrophobic surface, molecules move apart and local water becomes strongly bonded, inert, and viscous and accumulates large cations, univalent anions, and compatible solutes. Proteins and many other biopolymers have patchy surfaces which therefore induce, by the two mechanisms described, patchy interfacial water structures, which extended appreciable distances from the surface. The reason for many conflicting experimental results now becomes apparent. Average values of properties of water measured in gels, cells, or solutions of proteins are often not very different from the same properties of normal water, giving no indication that they are averages of extreme values. To detect the operation of this phenomenon, it is necessary to probe selectively a single abnormal population. Examples of such experiments are given. It is shown that this collective behavior of water molecules amounts to a considerable biological force, which can be equivalent to a pressure of 1,000 atm (1.013 x 10(5) kPa). It is suggested that cells selectively accumulate K+ ions and compatible solutes to avoid extremes of water structure in their aqueous compartments, but that cation pumps and other enzymes exploit the different solvent properties and reactivities of water to perform work of transport or synthesis.

Adverse reproductive outcomes among female veterinarians.

Because female veterinarians are exposed to several known reproductive hazards, the authors conducted a reproductive survey of all female graduates of a US veterinary school (n = 537) and law school (comparison group, n = 794). Analysis was confined to pregnancies completed after the second year of professional school and from 1966 to 1986. Based on one randomly chosen eligible pregnancy per woman (veterinarians, n = 176; lawyers, n = 229), spontaneous abortion rates, adjusted for elective abortions, were 13.3% for the veterinarians and 15.1% for the lawyers; these did not differ significantly. A Cox life table regression model controlling for age, smoking, alcohol use, and prior spontaneous abortion also showed no significant difference in spontaneous abortion rates between the two populations. Using all pregnancies, veterinarians who reported performing five or more radiographic examinations per week had a marginally elevated risk of spontaneous abortion, but the statistical significance disappeared when analysis was limited to one random pregnancy per woman. For one random eligible birth per woman, the mean birth weight did not differ significantly between the veterinarians and lawyers, even after controlling for possible confounders in regression analyses. A higher rate of reportable birth defects was observed among the veterinarians than among the lawyers (relative risk = 4.2, 95% confidence interval 1.2-15.1), but this unexpected result must be considered hypothesis-generating. The authors did not find an overall increased risk for spontaneous abortion or low birth weight infants among veterinarians compared with lawyers, but veterinarians who reported performing five or more radiographic examinations per week may have been at increased risk for spontaneous abortion.

Changes in ionic selectivity with changes in density of water in gels and cells.

Gels equilibrated with aqueous solutions of impermeant solutes reached a steady state in which, in the absence of a pressure difference, the activity of water in the pores of the gel was higher than that of water in the external solution. The chemical potential of water in the gel/polymer solution slurry was higher than that in the supernatant polymer solution removed from the gel. Water in the pores of the gel decreased in density to 0.96 as increasing osmotic stress was applied. It is argued that at constant temperature and pressure water can equilibrate between two compartments of unequal osmolality only by adjusting its molar volume. Experiments showed that when gel water had a higher activity than external water it was K(+) selective; when it had a lower activity it was Na(+) selective. It is proposed that a continuous spectrum of water structures can exist in these two compartment systems from dense, reactive, weakly-bonded water which selects highly hydrated ions, to expanded, stretched, unreactive, viscous water which is strongly hydrogen bonded and selects K(+) and univalent anions. These findings are related to the state and properties of cytoplasmic water which is probably held under osmotic stress by the activity of the sodium pump.

Epistaxis due to glutaraldehyde exposure.

Glutaraldehyde is commonly used as a cold disinfecting agent in the hospital setting and may cause irritation of skin, mucous membranes, and the upper respiratory tract in exposed workers. We report an unusual case of recurrent epistaxis associated with other symptoms of upper respiratory tract irritation and skin rash in a hospital employee using glutaraldehyde for sterilization of endoscopy equipment. A visit to the workplace revealed inadequate personal protective measures and inadequate local ventilation. High-risk work practices contributing to the hazard included soaking of endoscopy equipment in uncovered basins, manual pouring of concentrated glutaraldehyde solutions without the use of proper protective measures, and the use of paper masks, which provide inadequate protection from solvent vapors. The patient's symptoms resolved with the implementation of personal protective measures and engineering controls.

Localization of a nonintercalative DNA binding antitumour drug in mitochondria: relationship to multidrug resistance.

The bis-(n-butyl) quaternary salt of N,N'-bis-(6-quinolyl)terephthalamide (QBQ), a fluorescent antitumour compound in the phthalanilide series which is thought to bind to the minor groove of the DNA double helix, has been investigated with respect to its in vitro activity and subcellular localization. Cultured MCF-7 human breast carcinoma cells concentrated QBQ in mitochondria by a time-dependent process which was inhibited by the ionophore valinomycin, suggesting a possible mode of antitumour action of QBQ through mitochondrial poisoning. Growth of cultured P388 murine leukaemia cells was inhibited 50% in the presence of 0.52 microM QBQ and multidrug-resistant P388 sublines developed for resistance to actinomycin D, vincristine, Adriamycin and the phthalanilide NSC 38280 were cross-resistant to the drug. Cross-resistance was reduced in all lines by the presence of 11 microM verapamil, suggesting that a transport resistance mechanism operates on QBQ. The actinomycin D-resistant P388 cell line was found to be cross-resistant to the aromatic cations rhodamine 123, which binds to proteins, and ethidium and pyronin Y, which bind intercalatively to DNA. Thus mitochondrion-specific drugs with different macromolecular binding properties all appear to be excluded by multidrug-resistant cells.