Single-step process to reconstitute cell membranes on solid supports.

A new technique is presented to create supported lipid bilayers from whole cell lipids without the use of detergent or solvent extraction. In a modification of the bubble collapse deposition (BCD) technique, an air bubble is created underwater and brought into contact with a population of cells. The high-energy air/water interface extracts the lipid component of the cell membrane, which can subsequently be redeposited as a fluid bilayer on another substrate. The resulting bilayers were characterized with fluorescence microscopy, and it was found that both leaflets of the cell membrane are transferred but the cytoskeleton is not. The resulting supported bilayer was fluid over an area much larger than a single cell, demonstrating the capacity to create large, continuous bilayer samples. This capability to create fluid, biologically relevant bilayers will facilitate the use of high-resolution scanning microscopy techniques in the study of membrane-related processes.

Hypobaric hypoxia: effects on early development of tryptophan oxygenase in neonatal rats.

Despite a reduction in liver and body weights of neonatal rats born and reared at a simulated altitude of 5790 meters (oxygen pressure, 76.36 millimeters of mercury), the hepatic enzyme tryptophan oxygenase develops prematurely in these stressed animals as compared to controls reared at sea level. Also, the specific activities remain distinctly elevated through the first 9 days of age; thus, the competence for premature synthesis ot tryptophan oxygenase is confirmed in neonatal rats.

Wavelet analysis of the frontal auditory evoked potentials obtained in the passive oddball paradigm in healthy subjects and schizophrenics.

The goal of the present study was to apply the oscillatory brain dynamics model to the structural and quantitative analysis of neurocognitive functions considered as a potential marker of schizophrenia. This was achieved in tests of the detection of auditory events deviating in the regular auditory stream (oddball paradigm, MMN effect). It was hypothesized that the post-stimulus peaks of the oscillation power localized in post-stimulus time in the definite EEG oscillators represented neuro-electrical 'events' evoked in the specific neuronal nets characterized by this oscillation frequency band. We suggest that the time-frequency destination of these events related to the activation of the functional neuronal nets could be used for the determination of specific neurocognitive functions. Thus it was an attempt to distinguish the different neuro-functional parts of auditory processing and to compare these results between healthy subjects and patients with schizophrenia. The present results demonstrate the significant difference between the frontal averaged EEG oscillatory dynamics in healthy subjects and patients with schizophrenia related to neurocognitive function marked by the MMN and orienting response N200/P300a.

L-dopa absorption and the pituitary-hypothalamic axis.

Administration of oral L-dopa is often used as a neuropharmacological probe to evaluate the pituitary hypothalamic axis. The effect of gastrointestinal absorption of L-dopa on the changes in plasma GH, PRL, and body temperature which occur after ingestion of this amino acid is unknown. Plasma L-dopa, GH, PRL, and rectal and skin temperatures were measured in 14 male volunteers after oral administration of 1.0 g measured in 24 men after random administration of L-dopa and a placebo. L-Dopa levels rose to 1.85 +/- 1.33 microgram/ml (mean +/- SD), but maximum plasma levels occurred at variable times from 30-230 min after drug administration. Plasma GH levels increased to 23.7 +/- 14.7 ng/ml, while PRL levels fell to 46.7 +/- 12.3% of the mean basal values. Rectal temperature decreased significantly in 3 of the men after L-dopa ingestion. Plasma GH levels after L-dopa correlated with the absorption of the drug (P less than 0.05) and inversely with the basal level of GH before L-dopa administration. There was no correlation between the basal PRL level or basal body temperature and the magnitude of the fall in PRL or body temperature after L-dopa administration. The variability of responses in GH, PRL, and body temperature after oral L-dopa ingestion is not the result of differences in absorption in the amino acid alone, and indicate either that there is a different sensitivity in the mechanisms that stimulate GH secretion and lower plasma PRL and body temperature, or that L-dopa acts at different sites to bring about each of these changes.

Thermoregulatory effects of centrally administered bombesin, bradykinin, and methionine-enkephalin.

Bombesin (BO, 100 ng), bradykinin (BR, 10 microgram), or methionine-enkephalin (EN, 10 microgram) was administered intracerebroventricularly to adult male rats at an environmental temperature of 4 degrees C, 22 degrees C, or 35 degrees C, and rectal (Tre) and tail-skin (Tsk) temperatures were monitored for 5 hours. At 4 degrees C and 22 degrees C BO-treated animals developed acute hypothermia (max delta Tre=-3.25 degrees C and -2.71 degrees C, respectively) which persisted for 2 hours (p less than 0.05). At 22 degrees C and at 300 min post-injection, BO-treated animals became significantly (p less than 0.05) hyperthermic (deltaTre = +1.28 degrees C) when compared to controls. While BR had no effects at 22 degrees C, en-injected rats demonstrated significant (p less than 0.05) hyperthermia from 180 min through 300 min (delta Tre=+1.40 degrees C). At 22 degrees C both BO and, surprisingly, EN increased Tsk (e.g. delta Tsk =+ 3.49 degrees C and + 2.01 degrees C at 60 min). At 35 degrees C EN elicited hyperthermia which was significantly (p less than 0.05) increased from time 0 at all sampling time (mean delta Tre =+ 1.85 degrees C) and from control levels at 300 min (delta Tre =+1.07 degrees C, p less than 0.05). BO again caused a significant (p less than 0.05, BO vs control, 30 min) decrement (delta Tre =-1.22 degrees C) followed by increments (p less than 0.05) from 12-0-300 min. We conclude that the hypothermic effect of BO is dependent upon environmental temperature, partially caused by vasodilation, and possible biphasic in nature; EN treatment generally elicits hyperthermia under these conditions while BR produced no effects on thermoregulation.

Malathion administration: effects on physiological and physical performance in the heat.

To determine the effects of low-dosage organophosphate administration on exercise in a hot environment, malathion (7.5 mg/day, 4 days) was administered IP to rats, and effected a 35% (p less than 0.01) reduction in plasma cholinesterase levels. Treadmill endurance (9.14 m/min, no incline, 35 degrees C ambient) was unaffected when the animals were exercised to hyperthermic exhaustion (Tre approximately 43 degrees C). While rates of heat gain were similar between groups, malathion-treated rats displayed higher Tsk (p less than 0.05) at a number of sampling times during the treadmill run. While creatine phosphokinase levels were unaffected by either cholinesterase inhibition or exercise in the heat, lactate dehydrogenase activities were increased (p less than 0.01) in both groups following hyperthermic exhaustion. Although plasma levels of lactate, potassium, urea nitrogen, and creatinine were all significantly (p less than 0.01) increased as a result of exercise in the heat, these increments were not exacerbated by cholinesterase inhibition. Results generally indicated that at this moderate level cholinesterase inhibition, malathion administration did not adversely affect physiological, physical, or thermoregulatory efficacy.

Alterations of rat liver subsequent to heat overload.

Since pathological changes in the liver are among the consistent findings in humans subsequent to heatstroke, specimens were taken from the liver in rats during a study to assess the rat as a model for human heatstroke. Tissues from four groups of rats were processed for light and electron microscopy. The groups consisted of control rats, rats run to exhaustion at 5 C, rats exhausted at 26 C, and rats restrained at 41.5 C until their rectal temperatures reached 42.3 C. Exhaustive exercise at 5 C produced neither fatalities nor pathological changes in the livers. Exhaustive exercise at 26 C and restraint at 41.5 C were fatal for most rats. Histological and/or ultrastructural changes, which included centrilobular necrosis, vacuolization and diminution of hepatocellular microvilli, and loss of sinusoidal endothelium, were observed in livers from rats that were run to exhaustion at 26 C and from those rats restrained at 41.5 C. This work supports the validity of the rat model, since human heatstroke results in similar hepatic changes.

Heat- and exercise-induced hyperthermia: effects on high-energy phosphates.

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.

Hypo- and hyperglycemia in rats: effects on endurance and heat/exercise injury.

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.

Hypothermia induced by 5-thio-D-glucose: Effects on treadmill performance in the heat.

In continuing our studies on the effects of preinduced hypothermia on the endurance capacities, thermoregulatory responses, and clinical chemical indices of heat injury, 10 mg of 5-thio-D-glucose (5-TG) were administered intravenously to restrained rats kept at 4 degrees C. When rectal temperatures (Tre) fell to 29-30 degrees C, the rats were removed to a hot environment (35 degrees C), where they exercised on a level treadmill (9.14 m/min) to hyperthermic exhaustion (Tre = 41.5-43 degrees C). Preinduced hypothermia was effective in significantly (p < 0.001) prolonging the time to hyperthermic exhaustion. In these hypothermic rats, increments in Tre (degree C/min) while on the treadmill were significantly (p < 0.001) increased while rates of skin temperature (Tsk) heating were significantly (p < 0.001) reduced when compared to normothermic controls. Administration of 5-TG effected significant (p < 0.001) hyperglycemia, which returned to control levels following the exhaustive run in the heat. Prolonged endurance times among the hypothermic rats caused slight increases in the levels of circulating plasma indices of heat/exercise injury. We concluded from these studies that hypothermia induced by 5-TG administration and cold exposure is effective in increasing the endurance capacity of rats exercising in the heat. However, homeostatic mechanisms supercede to increase the heating rate, and thus return Tre to equilibrium levels.

Effect of noise on the vestibular system - Vestibular evoked potential studies in rats.

Studies have shown that in order for sound to affect the vestibular end organs in the inner ear, very high intensities are required. Furthermore, in patients with noise induced hearing loss, vestibular signs, if present, are subclinical. In order to study possible auditory-vestibular interactions in a more controlled fashion, using physiological sound intensities, the present study used short latency vestibular evoked potentials (VsEPs) to impulses of angular (15,000 degrees /sec(2), risetime 1.5 msec) and linear (3-5 g, risetime 1.5 msec) acceleration were used to study the possible effects of sound on peripheral vestibular function in rats. Four different paradigms were used: a - an intense (135 dB pe SPL) click stimulus was presented 5 msec before the linear acceleration impulse and the VsEP to 128 stimuli were recorded with and without this click stimulus. There was no effect of the preceding intense click on the first wave (reflecting end organ activity) of the linear VsEP. b - 113 dB SPL white noise "masking" was presented while the VsEPs were elicited. A 10-20% reduction in the amplitude of the first VsEP wave was seen during the noise exposure, but 5 minutes after this exposure, there was almost complete recovery to pre-exposure amplitude. c - 113 dB SPL noise was presented for one hour and VsEPs were recorded within 15 minutes of cessation of the noise. The auditory nerve-brainstem-evoked response showed a temporary threshold shift while there was no effect on the VsEP. d - 113 dB SPL white noise was presented for 12 hours per day for 21 consecutive days. Auditory nerve-brainstem-evoked responses and vestibular (VsEPs) function were studied one week after the conclusion of the noise exposure. Auditory function was severely permanently depressed (40 dB threshold elevation and clear histological damage) while the amplitude of wave 1 of the VsEP was not affected. It seems therefore that even though intense noise clearly affects the cochlea and may have a "masking" effect on the vestibular end organs, the intensities used in this study (113 dB SPL) are not able to produce a long-term noise induced vestibular disorder in the initially normal ear. These differences between the response of the cochlear and vestibular end organs to noise may be due to dissimilarities in their acoustic impedances and/or their electrical resting potential.

Use of evoked potentials to objectively differentiate between selective vulnerability of cochlear and vestibular end organ function.

Auditory nerve brainstem evoked responses (ABR) have been used for several decades to investigate cochlear function. Recently techniques have been developed to elicit similar recordings from the vestibular end organs - short latency vestibular evoked potentials (VsEPs). Both ABR and VsEP reflect appropriate end organ function and may therefore be used to investigate the vulnerability of these end organs to various experimental insults, such as noise exposure and ototoxic drugs.

Acting out and transference themes induced by successive pregnancies of the analyst.

The analyst's pregnancy can be considered a major organiser of the unfolding transference. In a detailed account of the analysis of a female patient who was confronted twice with the pregnancy of the analyst, the similarities and differences of the transference on both occasions are highlighted, with special emphasis on the occurrence of acting out. An analyst's pregnancy intensifies the transference and requires from the patient the capacity to experience the intensity of the evoked feelings. Accordingly, acting out is shown to be more vehement in the course of both pregnancies. The further the analytical process has evolved, the better these feelings are tolerated and the more susceptible they are to subsequent analysis.

Effect of death anxiety on perception of death-related humor.

Scores on a humor scale containing both death-related and non-death-related items were compared among three groups of 10 college students who scored high, medium, or low on death anxiety. Ratings of humor differed significantly among the groups, but there was no significant interaction between death anxiety and ratings of death-related humor. Subjects high in death anxiety showed lower humor ratings over-all than the other two groups.