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Isothermal vapor−liquid equilibria, VLE, excess Gibbs energies, , excess molar enthalpies, , and excess molar volumes, , were determined for the binary mixture trichloromethane + 1,2-epoxybutane at (288.15, 298.15, and 313.15) K and at atmospheric pressure. All excess properties are negative. The vapor−liquid equilibrium data are thermodynamically consistent and have been fitted to the Redlich−Kister equation. The influence of temperature has been discussed, and the relative magnitudes and signs of the excess properties have been outlined in terms of molecular interactions. Smooth representations of the results are presented.

Excess molar enthalpies H E m of dimethylcarbonate, diethylcarbonate or propylene carbonate + trans -1,2-dichloroethylene, + trichloroethylene, and + tetrachloroethylene, respectively have been determined at 298.15 K using an LKB flow-microcalorimeter. Experimental data have been correlated by means of the Redlich-Kister equation and adjustable parameters have been evaluated by least-squares analysis. The H E m values range from a minimum value of −1000 J mol −1 for diethylcarbonate + trans -1,2-dichloroethylene up to a maximum of 920 J mol −1 for dimethylcarbonate + tetrachloroethylene. For each series of mixtures, a systematic increase in H E m with an increase in the number of Cl atoms in the chloroalkene molecule has been noted. The results are discussed in terms of the molecular interactions.

Excess molar volumes at 298.15 K are reported for the binary systems containing toluene, p-xylene or pseudo-cumene + 2-propanone, 2-butanone, 2-pentanone, 2-octanone or 2-undecanone. All experimental curves present negative excess volumes, with the sole exception of the pseudo-cumene(1) + 2-propanone(2) mixture. The experimental data are examined by an extended cell model.

A comparative study of the respective performances of total internal reflection fluorescence (TIRF) prisms and fibre optic sensors in terms of their detection capabilities is presented. Theoretical models based on geometrical considerations described the excitation and collection efficiencies of the two optical systems. The models are shown to be in excellent agreement with the experimental TIRF obtained from the adsorption of albumin onto prism or fibre surfaces. Improvements in system performance, based on optimization of the optical configurations, have been evaluated. The studies demonstrate that, in terms of the requirements of biosensor devices, in which compactness and high efficiencies are paramount, fibre optic systems are superior to prism systems.

This work deals with the realization of an innovative wearable system for detecting current cardiac status. Signals acquired necessary to detect this status are the breathing signal, the heart apex pulse and the heart mechanical behavior. This system is based on a bi-modal sensor (an ultrasound transducer constituted by PVDF polymer) able to switch its sensitivity frequency range from low to high. The transducer, which has a low Q factor in order to exhibit a large broad bandwidth, is placed inside a textile belt. The wearable system is able to detect cardiac sounds from which the heart beat and the respiratory signal can be extracted, to generate ultrasound signals which can bounce off the heart, and to receive the back-propagated echoes. Innovative electronic tactics are implemented for maximizing sensor sensitivity at low frequency, saving power consumption and, at the same time, providing the right amount of energy for ultrasound investigation. The system is completely portable and wearable, powered by a rechargeable battery.

This paper describes a composite transducer for tactile sensing, whose skin-like structure makes it potentially useful in prosthetics as well as in robotics. Such transducer comprises an "epidermal", thin film, polyvinylidene fluoride (PVF 2 ) sensor and two inner layers consisting of a conductive rubber sheet and of an array of 128 PVF 2 sensors, which are intended to reproduce in part some mechanical features and sensing capabilities of the human dermis. The proposed transducer has been tested and its ability to detect, by touch, hardness, thermal conductivity and surface texture of objects, as well as contact pressure has been assessed. Although much work is still needed to obtain a really usable device, sensitivity, linearity and bandwidth of the present tactile transducer, along with its wide range of sensorial capabilities, strongly encourage further development.

A partial implementation of a multielement tactile sensor based on piezoelectric polymer technology is presented. The sensor's ability to resolve the shear stress component acting on it under axisymmetric, normal loading at its boundary is demonstrated. This feature is thought to be instrumental in revealing slippage detection during object grasping and manipulation. >

Knowledge of respiratory activity is of interest in patients with cardiac, pulmonary and neurological diseases; moreover, it is helpful for a proper evaluation of the autonomic nervous system influence on cardiac activity. To achieve 24-hour recording of ECG and respiratory activity an original solution was provided by the use of a piezoelectric transducer (PVDF) implemented in a FM 2-channel Holter recorder. A computer program for the dynamic analysis of the respiratory signal over the 24 hours, oriented to the detection of apnea and to the derivation of the clinically most significant parameters (such as respiratory rate, tidal volume, total inspiratory and expiratory time), was developed and applied in a preliminary group of 13 normal controls. A night-time decrease in respiratory rate was observed due to an increase in both inspiratory and expiratory time, together with a corresponding decrease in tidal volume presumably related to reduced metabolic demand. An analysis of the influence of the respiratory rate and the "computed tidal volume" upon R-R spectral indexes was performed. >

A new approach is introduced for deriving the respiratory signal from a single-lead electrocardiogram (ECG) by adaptive filtering. The method uses the R-R interval and the R-wave amplitude time series, extracted from the ECG signal, as inputs to the filter, the respiratory activity is estimated as its output. The adaptive filtering is able to enhance the common component between the above series (namely the respiratory influence), attenuating the uncorrelated noise. More than 170 hours of ECG and respiratory signal were collected. Least mean squares (LMSs) and recursive least squares (RLSs) adaptive filtering methods were applied to obtain the estimate of the respiratory signal. Visual inspection and spectral analysis were used to evaluate the performance of the filtering by comparison with a true respiratory signal obtained by a piezoelectric transducer. The RLS adaptive filtering technique was more effective than LMS in producing an 'ECG-derived' respiratory signal. This approach adds clinically important information to conventional ECG analysis. >

The nonverbal expression of the emotions, especially in the human face, has rapidly become an area of intense interest in computer science and robotics. Exploring the emotions as a link between external events and behavioural responses, artificial intelligence designers and psychologists are approaching a theoretical understanding of foundational principles which will be key to the physical embodiment of artificial intelligence. In fact, it has been well demonstrated that many important aspects of intelligence are grounded in intimate communication with the physical world- so-called embodied intelligence . It follows naturally, then, that recent advances in emotive artificial intelligence show clear and undeniable broadening in the capacities of biologically-inspired robots to survive and thrive in a social environment. The means by which AI may express its foundling emotions are clearly integral to such capacities. In effect: powerful facial expressions are critical to the development of intelligent, sociable robots. Following discussion the importance of the nonverbal expression of emotions in humans and robots, this paper describes methods used in robotically emulating nonverbal expressions using human-like robotic faces. Furthermore, it describes the potentially revolutionary impact of electroactive polymer (EAP) actuators as artificial muscles for such robotic devices.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

To obtain information on the mechanisms of hepatocellular damage and the determinants of response to interferon, hepatitis C virus (HCV) genotype, tissue HCV antigens, hepatocellular expression of HLA-A,B,C and intercellular adhesion-1 molecules, and the number of lobular T lymphocytes were studied in 38 anti-HCV-positive patients. 14 patients did not show a primary response to interferon treatment. HCV genotype 1b was detected in 11 of them. They displayed higher scores of HCV-positive hepatocytes, HLA-A,B,C, and ICAM-1 molecules expression than with the responders. HCV-infected hepatocytes maintained the capacity to express HLA-A,B,C and ICAM-1 molecules. CD8-positive T cells in contact with infected hepatocytes and Councilman-like bodies were observed. A significant correlation was found between the number of lobular CD8-positive T cells and alanine amino transferase levels. No differences were observed in clinical, biochemical, and histological features between patients with high and low number of hepatocytes containing HCV antigens. These data suggest a prominent role of T cell-mediated cytotoxicity in the genesis of hepatocellular damage. The high expression of interferon-inducible antigens like HLA-A,B,C molecules suggests the presence of strong activation of the interferon system possibly related to high HCV replication in nonresponder patients infected with genotype 1b.

This chapter elaborates experimental methodologies in the evaluation of detection capabilities of a fiber optic total internal reflection fluorescence (TIRF) immunosensor. TIRF systems that couple the specificity of the antibody antigen reaction with the spatial selectivity of the evanescent wave, appear close to attaining this goal, and in addition, are easily miniaturizable. The sensor operates in the transmission mode, in which an antibody coated fiber traverses the center of the measuring cell. Tests on antibody immobilization using enzyme linked immunosorbent assay (ELISA) have been conducted on fiber surfaces, and the system has been validated using albumin and anti-albumin. The response of the implemented sensor has been evaluated using immobilized anti-BSA antibodies and FITC-labeled BSA in solution. The sensor was also tested in order to investigate its minimum detection limit. Samples of increasing antigen concentrations were introduced into the measurement cell. The results show that one of the methods to decrease the minimum detection limit could be by the use of fluorescent markers with greater efficiency.

We have employed the primed constant infusion technique to investigate the metabolic effects of the organophosphate antidote, atropine, on glucose homeostasis in rats. This method utilizes the radioisotopes 6-3H-glucose to measure production and uptake and U-14C-glucose to measure oxidation. Our data indicate that glucose production significantly (p less than 0.05) increased (24.0 +/- 2.0 vs. 30.9 +/- 2.6 mumoles.kg-1.min-1) following atropine administration. The elevated rate of glucose turnover was associated with concomitant increases in glucose oxidation (8.3 +/- 0.6 vs. 12.0 +/- 0.8, mumoles.kg-1.min-1), the percent of glucose uptake oxidized (37.2 +/- 2.0 vs. 44.6 +/- 2.6), and the percent carbon dioxide produced from glucose (8.4 +/- 0.7 vs. 12.0 +/- 1.8). Presumably, these glucokinetic changes were mediated by elevated plasma catecholamines (Epi: 166 +/- 19 vs. 271 +/- 50 pg/ml; Norepi: 262 +/- 24 vs. 525 +/- 63 pg/ml, p less than 0.05) since other glucoregulatory hormones (insulin, glucagon, and corticosterone) were not significantly affected by atropine administration. In addition, there was no change in VO2 associated with atropine administration. These data indicate that atropine enhances glucose production and utilization; such effects could be ergogenic during exercise in thermoneutral conditions.

The diffusion of quinidine sulphate through a polydimethylsiloxane film containing 20% SiO 2 filler was studied in a cell with two stirred compartments separating the film, taking into account all the forms (neutral, mono- and di-protonated) of quinidine in the buffered aqueous solutions of the cell compartments. The theoretical treatment leads to a relationship between the quinidine concentration across the film thickness as a function of the diffusion time, allowing for the chemical reactions in the cell compartments at constant pH, the solubility of quinidine in the polymer phase and the adsorption of quinidine onto the SiO 2 phase. A solution for large values of time is given, showing a linear dependence of In Δc on time.

A multielement ultrasonic (US) ranging array has been realized for mounting on an articulated robotic finger. The ranging system consists of concave piezoelectric polymer-based US transducers arranged in a three-dimensional (3D) `lsfoveal'rs disposition so that the transducer radius decreases and the working frequency increases from the base towards the tip of the finger. Each undulated element is connected to a computer-controlled scanning and amplifying electronic unit, and operates either as a transmitter or a receiver. The general features of the US sensor array are discussed and the problems of detecting and reconstructing by triangulation the orientation of randomly located surfaces, of detecting the presence of 3D objects and of reconstructing their shape by US proximity sensing, are addressed.

I nsulin degradation in human erythrocytes obtained from normal subjects is studied. Under the experimental conditions used, insulin binding and insulin degradation are strictly correlated, and no degrading activity is released in incubation medium. Comparative analysis of hemolysate and membranes shows that hemolysate possesses a definite insulin-degrading activity which is not linked to the hemoglobin molecule; the km of this enzymatic activity is of the same order of magnitude as that reported in other cells. At the concentration and in the condition used in this study, membranes degrade insulin at a lower rate than hemolysate.

Several possible configurations of ferroelectric polymer catheter-tip sensors for the detection of intracavitary pressure and sound are compared on the basis of calculated free-field voltage sensitivity. The design, construction and testing of a polyvinylidene fluoride (PVF2) catheter-tip transducer operating primarily in the extensional mode is described in detail. Compared in vitro with a commercial silicon strain-gauge microtransducer, the PVF2 sensor showed remarkable capability to detect faithfully pressure waveforms and sounds. Preliminary tests also demonstrated its ability to record, via the pyroelectric effect, thermal indicator dilution curves which compare well with those provided by a commercial thermistor catheter. In vivo experiments confirm the effectiveness of the PVF2 sensor. The major limitation of the ferroelectric devices is the lack of DC response, which makes them generally unable to measure static values of the parameters of interest.

1. 1.|Dinitrophenol (DNP) was administered to rats in two equal dosages (20 mg/kg, 30 min interval); the second injection was followed immediately by exercise (9.14 m/min) in the heat (30°C) or at room temperature (21°C). 2. 2.|At 21°C control (saline-treated) rats manifested a mean endurance of 94 min which was reduced to 32 min among DNP-treated animals. 3. 3.|At 30°C, control rats ran for 65 min ( δT re /min = 0.05°C) while DNP-treated animals had a mean endurance of only 12 min ( δT re /min = 0.22°C). 4. 4.|DNP-treated rats (30°C) manifested no decrements in tail-skin heat loss ( δT sk /min = 0.17°C vs 0.10° C ) or saliva secretion (0.78 g/min, DNP vs. 0.19 g/min, control) for their brief treadmill duration. 5. 5.|The increased metabolic heat production of DNP severely reduced performance.

To identify and quantitate the effects of chronic chlorpromazine (CPZ) administration on the ability to work in the heat, 2 mg CPZ were administered by intraperitoneal injection daily for 14 days to rats weighing between 250 and 350 g at the time of experimentation. When these animals exercised in the heat (35 degrees C) to hyperthermic exhaustion (Tre = 42.5-43 degrees C), it was demonstrated that their endurance capacity was significantly reduced (P less than 0.001) when compared with saline-treated controls. Increments in rectal temperature while on the treadmill were significantly (P less than 0.02) elevated among th CPZ-treated rats. Exercise on the treadmill to hyperthermic exhaustion resulted in significantly (P less than 0.001) increased circulating levels of lactate and potassium when these were compared in blood samples taken immediately before and after exercise in the heat for both groups, but creatine phosphokinase levels were unaffected. Additionally, lactate levels were significantly (P less than 0.05) increased in the postrun blood samples of CPZ-treated rats when compared with the appropriate saline-treated controls. We concluded from these studies that chronic administration of CPZ in rats reduces their ability to work in the heat. Further, their rate of heat gain while exercising in the heat is increased, and the combined effects of exercise in the heat and CPZ administration exacerbated the effects on the clinical chemical indices of heat-exercise injury.

Exogenously administered monoamines may elicit variable thermoregulatory responses dependent on dosage, species, site of administration, ambient temperature, etc. In an attempt to reconcile several inconsistencies, we have undertaken a series of studies related to monoaminergic control of temperature regulation. Thus, intraventricular administration of serotonin (2.64-26.4 mug) and norepinephrine (3.3-32.8 mug) in rats evoked acute (15-60 min) dose-dependent hypothermic responses (delta Tre = 2 degrees C) that were gradually superseded by significant, more persistent hyperthermia (delta Tre = 1 degreee C). Administration of chlorimipramine or imipramine (total dose 40 mug), even in monoamine-depleted animals, caused long-lasting hyperthermic responses, presumably by the prevention of reuptake of serotonin and norepinephrine at nerve terminals involved in thermoregulation. Pretreatment with the serotonin inhibitor cyproheptadine (4o mug) attenuated the hyperthermia achieved by central administration of chlorimipramine alone. We conclude that both monoamines can act as thermogenic agents under the conditions of these experiments.

An object position and orientation recognizing device using pyroelectric polyvinylidene fluoride (PVF 2 ) 16 × 16 sensor matrix is proposed in this paper. A theoretical analysis, based on a three layer sensor model (absorber-pyroelectric film-substrate), of the response of such substrated sensor to rectangular pulse thermal radiation is presented along with its experimental validation. The electronic part and the recognition operation are also briefly described. Satisfactory recognition results have been obtained from a prototype of the proposed device.

A thermodynamic method has been developed to provide a direct semi-integral criterion of the consistency of liquid—vapour equilibrium data under isobaric and isothermal conditions for binary mixtures with associations between the components in the two phases. The method differs from others by the use of the equality between the microscopic and the macroscopic chemical potentials of the species in both phases. This permits the introduction of fugacity and activity coefficients, which are more convenient to use. Furthermore, it does not require any information on the state of the association in the liquid. The semi-integral criterion enables one to examine without any analytical or graphical difficulty the consistency of the data throughout the whole concentration range of the components.

The viscometric behavior of linear polycaprolactam has been studied in the absence of the electroviscous effect in aqueous solvents containing 85% and 64.5% formic acid and in trifluoroethanol, as a function of temperature and also under unperturbed conditions. Results are discussed in terms of the existing theories; in particular, the negative temperature coefficient of the intrinsic viscosity arises only from the variation of the expansion coefficient, the molecule in the unperturbed state being a normal random coil. The absence of aggregation and draining effects in the above solvents has been varified.

The gas chromatographic behaviour of C 1 C 5 alcohols and chloroform on Carbowax 400 was studied in the range 58–88°. The specific retention volumes were determined, and the deviations from the expected order of elution were investigated by calculating the activity coefficients and the thermodynamic excess functions. The F lory -H uggins theory was used to evaluate the statistical contribution made by the mixing of molecules of different sizes, and the results were interpreted on the basis of the theory of associated ideal solutions. The difference between the order of elution of alcohols and the order of their boiling points was found to be due to differences in their molecular volumes. On the other hand, the nature of the association between the alcohols and Carbowax 400 is not very different from that of the associated species in the pure alcohol samples. The relative volatilities may therefore be predicted from the F lory -H uggins theory.

It is demonstrated that application of Onsager's reciprocal relations, with coefficients dependent on the intensive characteristics of the system, to ordinary diffusion and to thermal diffusion still in the range of linearity of the phenomenological relations, enables diffusivity of the components to be expressed as a sum of two terms, one purely thermodynamic and the other also containing the hydrodynamic characteristics of the system. Combination of the two factors is explicit and very simple in the case of isothermal diffusion of dilute polymer solutions. When the thermodynamic factor is predominant there is a linear law relating diffusivity with concentration, coinciding with the equation confirmed experimentally in various polymer systems. In the limit, when the hydrodynamic factor reaches zero, Wagner's equation for the diffusion of solid PbCl in AgCl is obtained.

The viscometric properties of branched eight star shaped polycaprolactam have been determined. Measurements have been carried out at different temperatures in the solvents: 58% formic acid, 64·5% formic acid, 85% formic acid and m -cresol. By making use of the Kron and Ptitsyn formulations, it was possible to calculate values of intrinsic viscosity which were rather similar to the experimental ones; results indicate that the above polymer shows a configuration which is very near to the free-draining model in formic acid, while in m -cresol the non-draining model prevails. For the polymer in 64·5% formic acid, the plot intrinsic viscosity—temperature shows a sinusoidal shape; such a behaviour has also been noticed by other authors for different polymers; however, a satisfactory explanation of the phenomenon has not so far been given.

The data for the isobaric equilibrium in the acetic acid—trichloroethylene system were determined using an apparatus in which the liquid and vapour were made to circulate. Analysis of the data for this system, which is characterized by dimerization of the acetic acid in the vapour phase, permits application of the semi-integral consistency criterion formulated in Part I [1]. The results fully confirm the existence of only the dimer of acetic acid in the vapour phase. They also afford a test of the very good consistency of the equilibrium data when transferred from isobaric conditions to isothermal ones. Furthermore, they prove that the terms due to the non-ideal nature of the vapour phase make only a negligible contribution.

This paper deals with the demonstration of the nonexistence of complex conjugate roots and of real positive roots in the working equations of a previous work [1], where this nonexistence was not proved.

The application of trend surface analysis to mineral concentrates from pegmatites of the Nazareno - Cassiterita region disclosed a definitive pattern. The interpretation of the resulting surfaces for different minerals, indicated that the most important concentrations are located in the western portion of the region, near the Rio das Mortes, within amphibolitic rocks. Recent discoveries in that area stressed the efficiency of the trend surface technique when applied to such problerns.

To assess the role of high-energy phosphate compounds in the etiology of heat injury with respect to the release of intracellular constituents, the susceptibility of selected tissues to heat injury, and the shock-like demise of the animals, rats were exercised on a treadmill (9.14 m/min) in a hot environment (34.5-35 degrees C) to a rectal temperature (Tre) of 42.5-43 degrees C. In the heart, kidney, left lateral lobe of the liver, and gastrocnemius muscle extricated from animals immediately upon termination of the treadmill run, levels of glucose-6-phosphate (G-6-P), adenosine triphosphate (ATP), and creatine phosphate (CP) were unchanged when compared with sedentary controls. In animals which had been resuscitated by infusion of isotonic saline into a jugular catheter, levels of CP were significantly (p less than 0.025) elevated in gastrocnemius muscle. In rats which were unconscious and succumbing to the effects of hyperthermic injury, levels of hepatic G-6-P and ATP were significantly reduced (p less than 0.05, p less than 0.02, respectively). These results indicate that the combination of exhaustive excercise/heat injury had the most deleterious effects upon hepatic metabolism. However, while resuscitation with physiological saline may be accompanied by an increased synthesis of CP, hyperthermic exhaustion and the concomitant efflux of cellular constituents cannot be attributed to a depletion or even a decrement of high-energy phosphates in vital tissues.

Six highly motivated and trained military test subjects were exposed to a simulated altitude of 4267 m (477 torr) for 48 hours, prededed and followed by sea level runs lasting 32 hours. During each scenario tests subjects were required to perform their respective military tasks on a continual basis with sporadic rest not exceeding several hours. Extremely high levels of plasma cortisol prior to the start of each session and persistently elevated concentrations of urinary 17-OH corticosteroids at sea level were consistently observed. (This observation probably explains the relatively minor changes in adrenocortical output noted during acute exposure to hypobaric hypoxia. Analogous results were obtained for urinary cyclic AMP, i.e. elevated baseline levels and minimal response to high altitude. The results indicate an attenuated response as well as an association between urinary measures of adrenocortical activity and cyclic AMP excretion.

To investigate the hypothesis that circulating glucose levels may affect exercise performance and the severity of hyperthermic injury, rats were made hypoglycemic (n = 12, IV insulin, 4 U) or hyperglycemic (n = 12, IP glucose, 750mg) before exercise in the heat to hyperthermic exhaustion (Tco = 42.5-43 degrees C). The endurance of rats administered glucose was significantly greater than insulin-treated controls (n = 12). Hematocrit levels were unaffected by exercise in control and insulin-treated rats, but were significantly (p less than 0.01) increased in those glucose-treated. Lactate levels were increased (p less than 0.001) post-run in all groups, and these increments were exacerebated in glucose-treated rats. Glucose levels pre-run were decreased by insulin and increased by glucose, and remained depressed (p less than 0.01) post-run in the insulin-treated group. Potassium concentrations were reduced (p less than 0.05) by insulin administration. Urea nitrogen and creatinine were increased (p less than 0.001) post-run in all groups. We concluded that, while hyperglycemic rats had increased endurance compared to hypoglycemic animals, mortality of at least 50% in all groups was unaffected by circulating glucose levels.

To assess the effects of preinduced hyperthermia on the ability to exercise in the heat, prostaglandin E1 (PGE1) was administered intracerebroventricularly to male rats weighing 275–350 g. Following injection of PGE1, a fever of 2 degrees developed within 20–30 min, at which time a 1-ml blood sample was taken. When these animals exercised in the heat (37 degrees C) to hyperthermic exhaustion (42.5–43 degrees C), their endurance capacity was significantly reduced (P less than 0.001) when compared with controls. Exercise to hyperthermic exhaustion resulted in significantly (P less than 0.05, minimal) increased plasma levels of lactate, potassium, and urea nitrogen in both control animals and those receiving PGE1. However, PGE1 pretreatment did not exacerbate these increments. Plasma glucose and sodium levels were significantly (P less than 0.05) increased in PGE1-treated animals, whereas glucose levels were reduced significantly (P less than 0.05) in both groups postrun. We concluded that preinduced hyperthermia severely reduces the ability to work in the heat. Although the clinical chemical indices of heat injury are unaffected by PGE1 pretreatment, the effects of PGE1 administration on circulating levels of glucose and sodium require further study.

To study the effects of preinduced hypothermia on the physiological and thermoregulatory responses to exercise in the heat rats were intravenously administered either 100 micrograms of chlorpromazine (CPZ) or 200 mg/kg of L-tryptophan (L-Trp) under restraint in a cold (4 degrees C) environment. When rectal temperatures (Tre) reached 32–33 degrees C the rats were removed to a hot environment (35 degrees C) where they ran on a level treadmill (9.14 m/min) to hyperthermic exhaustion (Tre, 42.5–43 degrees C). Both CPZ and L-trp hypothermia was effective in increasing significantly (P less than 0.001) the time to hyperthermic exhaustion. However, the maximal Tre and skin temperatures (Tsk) attained were unaffected by either treatment. When the rats exercised on the treadmill, increments (degrees C/min) in Tre and Tsk were significantly (P less than 0.02, minimal) greater for the initially hypothermic animals compared to normothermic controls. Cooling rates were unaffected by either treatment. We concluded from these studies that, although preinduced hypothermia is extremely effective in prolonging the time to hyperthermic exhaustion, no additional beneficial thermoregulatory responses accrued as a result of this treatment.

To quantitate the effects of ingestion of ethanol (EtOH)-water mixtures on the ability to work in the heat (35 degrees C), adult male rats (250-350 g) were given 0, 4, 8, 12, or 16% EtOH as the sole source of drinking water for 14 days. The endurance capacity (treadmill time) of rats drinking 4% EtOH was similar to that of rats consuming water (32 vs. 32.9 min, respectively). However, the treadmill time of rats drinking of 16% EtOH was significantly (P less than 0.05) reduced when compared with that of animals drinking 4 or 8% EtOH. Maximal rectal and skin temperatures were likewise lower in the group consuming 16% EtOH, whereas increments in rectal and skin temperatures during treadmill exercise were unaffected. Although hematocrit and plasma protein levels were unaltered, plasma levels of the commonly reported indices of heat-exercise injury were exacerbated by consumption of increasing concentrations of EtOH. We concluded that ingestion of EtOH for 2 wk had minimal effects on thermoregulation and that the decrements in work capacity noted were probably the result of alterations in hepatic and muscle metabolism.

Adult male mice were administered several doses of 5-thio-D-glucose (5-TG) at two environmental temperatures, 4 and 22 degrees C. Both intracerebroventricular (icv) and intraperitoneal (ip) administration of 5-TG resulted in significant (P < 0.05 to P < 0.001) decrements in rectal temperature (Tre) that were dose dependent. After 30 min, the hypothermic effects were significantly (P < 0.001, icv, 100 microgram) exacerbated by cold exposure (4 vs. 22 degrees C) and were likewise intensified significantly (P < 0.005, 45 min, fed vs. 18 h fasted) by food deprivation. These reductions in Tre were accompanied by significant (P < 0.001) increases in circulating levels of glucose. The present results indicate that 5-TG may be eliciting both central and peripheral cellular glucopenia concomitant with circulatory hyperglycemia; thus, the resultant hypothermia may be arising from competitive inhibition of glycolysis by 5-TG intermediates as well as reduced availability of tissue glucose.

Atropine and other anticholinergic drugs are widely used in common medications and in the treatment of organophosphate poisoning. Man dissipates heat by the evaporation of sweat. Analogously, rats spread saliva over their bodies for evaporative cooling. Atropine inhibits both sweating and salivation. Therefore, we sought to quantitate the effects of atropine in our rat heatstroke model. While heat-stressing adult male rats of 500 or 250 g at 41.5 degrees C, we measured the effects of i.v. atropine (10-4000 micrograms X kg-1) on the following: heating rate (HR), % wt loss (saliva production), and fecal loss (intestinal motility). HR (degree C X min-1) was the most sensitive index of drug activity with a 200 micrograms X kg-1 dose (equivalent to 2 mg in man for organophosphate poisoning) eliciting an increased HR from 0.022 degrees C (saline) to 0.087 degrees C X min-1 (atropine). Atropine (200 micrograms X kg-1) increased HR even if administered 3 h prior to heat exposure. Large (500 g) rats showed an increase in HR with 25 micrograms X kg-1 of atropine, but 250 g rats required 50 micrograms X kg-1. This model could be used to assess the relative effects of other anticholinergic drugs and as a non-dehydrated heatstroke model.