Short-term REM sleep deprivation effect on temperature rhythm of rats.

Circadian rhythm of body temperature (CRT) is altered in endogenous depression and many psychiatric disorders. Even the sleep pattern is disrupted. Sleep deprivation alleviates symptoms in depression. The present study was conducted to find the role of noradrenergic innervation to the pineal gland in bringing about the effect of REM sleep deprivation (REMSD) on the CRT. Adult male Wistar rats (n = 12) divided into 2 groups were used for the study. The group I rats (n = 6) underwent superior cervical ganglionectomy and the group II rats (n = 6) were sham ganglionectomised. After recovery rats were given REMSD for 48 hours. The CRT was measured in three periods of the study i.e. basal, post operative and post REMSD. The results indicated REMSD increased the Amplitude and Mesor of the CRT in both the groups which was shortlasting and reversible thus suggesting non sympathetic mediation of the pineal in bringing about the circadian rhythm alteration due to REMSD.

Superior cervical ganglionectomy leads to dampening of amplitude of temperature rhythm in rats.

The circadian rhythm of body temperature (CRT) is a robust marker of the endogenous pacemaker function and is one of the most frequently studied rhythms. Melatonin, the main secretion of the pineal gland seems to have more of a thermomodulatory role in controlling the body temperature than having a direct role in thermoregulation. The sympathetic innervation to the pineal via the superior cervical ganglion determines the melatonin secretion, and superior cervical ganglionectomy (SCGx) decreases the secretion of melatonin. The present study was conducted on the Wistar rats (n = 12) to determine the role of melatonin in modulation of CRT. Adult male rats were either ganglionectomised (n = 6) or sham ganglionectomised (n = 6). Rectal temperature was recorded for CRT analysis. Cosinar analysis of the temperature record was done to get the acrophase, amplitude and mesor. Our results show that SCGx decreases the amplitude to the rhythm but has no effect on the mesor of the rhythm. Our study confirms that melatonin has little role to play in the thermoregulation and its role is mainly in thermomodulation.

Effect of Chyawanprash and vitamin C on glucose tolerance and lipoprotein profile.

Chyawanprash is an ancient Indian dietary supplement containing vitamin C (34 mg/100 g) derived from amla (Emblica officinalis). In addition, Chyawanprash also contains several other herbal products. The present study was designed to compare the effects of vitamin C with those of Chyawanprash. Ten normal healthy adult male volunteers (age 20-32 years) participated in the 16-week study. They were placed randomly in either the Chyawanprash group (n = 5) or vitamin C group (n = 5). Those in the former received 15 g/d of Chyawanprash while those in the latter received 500 mg/d vitamin C during the first 8 weeks of the study. For the next 8 weeks, no supplement was given. For each individual, an oral glucose tolerance test was performed, and lipoprotein profile in peripheral serum samples was determined at 0 weeks, 4 weeks, 8 weeks, 12 weeks and 16 weeks. In the Chyawanprash group, the 8 weeks Vs 0 weeks value (mean +/- S.D.) respectively for various indices which were significantly different were fasting plasma glucose (100.2 +/- 5.58 mg/dl vs 116.2 +/- 11.6 mg/dl), area under 2-h plasma glucose curve (245.9 +/- 15.13 mg.dl-1.h vs 280.8 +/- 37.09 mg.dl-1.h), HDL cholesterol (53.2 +/- 4.56 mg/dl vs 42.7 +/- 7.17 mg/dl), LDL cholesterol (82.4 +/- 8.80 mg/dl vs 98.26 +/- 12.07 mg/dl), LDL/HDL ratio (1.56 +/- 0.28 vs 2.38 +/- 0.63). In the Vitamin C group, only the LDL/HDL ratio was significantly lower at 8 weeks than at 0 weeks (1.99 +/- 0.44 vs 2.29 +/- 0.43). All the variables that changed significantly were no longer significantly different from the 0 weeks value at 16 weeks. Chyawanprash reduces postprandial glycemia in the oral glucose tolerance test and reduces blood cholesterol level to a significantly greater extent than vitamin C.

Retardation of coronary atherosclerosis with yoga lifestyle intervention.

BACKGROUND: Yoga has potential for benefit for patients with coronary artery disease though objective, angiographic studies are lacking. MATERIAL AND METHODS: We evaluated possible role of lifestyle modification incorporating yoga, on retardation of coronary atherosclerotic disease. In this prospective, randomized, controlled trial, 42 men with angiographically proven coronary artery disease (CAD) were randomized to control (n = 21) and yoga intervention group (n = 21) and were followed for one year. The active group was treated with a user-friendly program consisting of yoga, control of risk factors, diet control and moderate aerobic exercise. The control group was managed by conventional methods i.e. risk factor control and American Heart Association step I diet. RESULTS: At one year, the yoga groups showed significant reduction in number of anginal episodes per week, improved exercise capacity and decrease in body weight. Serum total cholesterol, LDL cholesterol and triglyceride levels also showed greater reductions as compared with control group. Revascularisation procedures (coronary angioplasty or bypass surgery) were less frequently required in the yoga group (one versus eight patients; relative risk = 5.45; P = 0.01). Coronary angiography repeated at one year showed that significantly more lesions regressed (20% versus 2%) and less lesions progressed (5% versus 37%) in the yoga group (chi-square = 24.9; P < 0.0001). The compliance to the total program was excellent and no side effects were observed. CONCLUSION: Yoga lifestyle intervention retards progression and increases regression of coronary atherosclerosis in patients with severe coronary artery disease. It also improves symptomatic status, functional class and risk factor profile.

Psychological impact of the Antarctic winter on Indian expeditioners.

The authors studied the psychological variables of 25 men who participated in the winter-over team of an Indian expedition to Antarctica for possible associations with seasonality and isolation. It was found that increased cigarette smoking was associated with the stress of the beginning of isolation (March), sleep difficulty was associated with midwinter (June), rapport was at a minimum at the point of maximum isolation in temporal terms (September), and decreased satisfaction with work and life situations was associated with continued isolation (December, January). The study suggested that variables postulated to affect performance undergo changes during the course of wintering over in Antarctica.

Lipid profile of coronary risk subjects following yogic lifestyle intervention.

The effect of yogic lifestyle on the lipid status was studied in angina patients and normal subjects with risk factors of coronary artery disease. The parameters included the body weight, estimation of serum cholesterol, triglycerides, HDL, LDL and the cholesterol - HDL ratio. A baseline evaluation was done and then the angina patients and risk factors subjects were randomly assigned as control (n = 41) and intervention (yoga) group (n = 52). Lifestyle advice was given to both the groups. An integrated course of yoga training was given for four days followed by practice at home. Serial evaluation of both the groups was done at four, 10 and 14 weeks. Dyslipidemia was a constant feature in all cases. An inconsistent pattern of change was observed in the control group of angina (n = 18) and risk factor subjects (n = 23). The subjects practising yoga showed a regular decrease in all lipid parameters except HDL. The effect started from four weeks and lasted for 14 weeks. Thus, the effect of yogic lifestyle on some of the modifiable risk factors could probably explain the preventive and therapeutic beneficial effect observed in coronary artery disease.

Gastro-intestinal effects of Indian spice mixture (Garam Masala).

Spices are a part of diet all over the world but the variety and quantity consumed in tropical countries is particularly significant. The intestinal transit time of Indians is shorter, and their stool weight larger than that of Europeans on a comparable fibre intake. Ingestion of chilli is associated with a faster whole gut transit time. There is hardly any human work on the effects of spices on intestinal transit or gastric emptying. To explore the effects of spices on gastro intestinal transit this study was conducted on 18 well nourished healthy human adult volunteers using Radiolabelled Idli with or without Garam Masala. On gastric scintigraphy the gastric emptying time was much faster in subjects when spicy meal was given. The t1/2 of the spicy meal, 40.09 +/- (p < 0.05) thus implying a faster transit through the stomach. In 17 out of the 18 subjects t1/2 of the spicy meal was consistently lower than that of spicefree meal. The lag phase of gastric emptying showed no significant difference. There was a tendency towards slower gastrocolic transit with Spicefree meal but more subjects need to be done to confirm this.

Glycaemic and insulinaemic responses to natural foods, frozen foods and their laboratory equivalents.

Glycaemic response to a food is determined by a large number of factors, of which composition is only one. The present study was designed to study the effect of composition and overnight refrigeration on the glycaemic response. The study involved determination of the glycaemic and insulinaemic response of healthy human volunteers to rice or potato, and to meals equivalent to these foods in terms of carbohydrate, protein, fat and fibre content; but made up of cornflour, casein, corn oil and cellulose. Further, each of these meals was served either freshly cooked, or after overnight storage in a refrigerator and rewarming. The natural foods led to a higher postprandial glycaemia than their respective equivalents, and the freshly cooked foods led to a higher glycaemic response than the refrigerated and rewarmed forms of the corresponding foods. No such consistent differences were observed in case of the insulinaemic responses. The difference in the glycaemic response to foods and their laboratory equivalents may be due to the unique physical arrangement of nutrients within the food or due to specific chemical differences in terms of macro-or micro-nutrients, non-nutrients or anti-nutrients. The difference in the glycaemic response to freshly cooked and refrigerated foods may be due to the formation of resistant starch during cold storage.

Study of pulmonary and autonomic functions of asthma patients after yoga training.

"The concept of yoga is helpful for the treatment of Bronchial Asthma", has created a great interest in the medical research field. In order to investigate whether autonomic functions and pulmonary functions are improved in asthma patients after short term yoga training, a study was conducted with nine diagnosed bronchial asthma patients. Yoga training was given for seven days in a camp in Adhyatma Sadhna Kendra, New Delhi. The autonomic function tests to measure the parasympathetic reactivity (Deep Breathing test, Valsalva Manouever), Sympathetic reactivity (Hand Grip test, Cold Pressure test), and pulmonary function tests FVC, FEV1, PEFR, PIF, BHT and CE were recorded before and after yoga training. The resting heart rate after yoga training (P < 0.05) was significantly decreased (89.55 +/- 18.46/min to 76.22 +/- 16.44/min). The sympathetic reactivity was reduced following yoga training as indicated by significant (P < 0.01) reduction in DBP after HGT. There was no change in parasympathetic reactivity. The FVC, FEV1, PEFR did not show any significant change. The PIF (P < 0.01), BHT (P < 0.01) and CE (P < 0.01) showed significant improvement. The results closely indicated the reduction in sympathetic reactivity and improvement in the pulmonary ventilation by way of relaxation of voluntary inspiratory and expiratory muscles. The "comprehensive yogic life style change programme for patients of Bronchial Asthma" have shown significant benefit even within a short period.

Effects of hypercapnia on metabolism, temperature, and ventilation during heat and fever.

We wished to determine whether 1) acute hypercapnia in cats changes metabolic heat production to affect temperature regulation and 2) heat exposure and fever affect the normal response. The effects of breathing 4% CO2 on O2 consumption (VO2), rectal temperature (Tre), and ventilation (V) were measured in five conscious resting cats. Cats were exposed to a normal (24-27 degrees C) chamber temperature (Ta) and a warm (33-34 degrees C) chamber Ta. Fever was produced by intravenous injection of Escherichia coli endotoxin (0.02 microgram/kg) at a normal Ta. In normothermic cats, hypercapnia decreased VO2 by approximately 40%, despite an increased V (approximately 100%), but Tre decreased only transiently and slightly compared with studies in which air was breathed throughout. During heat studies, average V was elevated but VO2 was markedly lower than at the normal Ta; Tre gradually increased. Hypercapnia combined with heat did not cause additional increases in VO2, nor did it cause a decrease in VO2, as at a normal Ta; however, the rate of rise of Tre during heat was slowed by hypercapnia. During febrigenesis, hypercapnia prevented the transient increase in VO2 observed when air was breathed and delayed the rate of rise in Tre. As Tre was falling in fever, hypercapnia depressed VO2 but did not affect Tre compared with fever studies in which air was breathed. Unlike heat exposure, hypercapnia had a further additive stimulatory effect on the increase in V at the onset of fever, and it increased V during the falling phase of fever when V had returned to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of local cooling on skin temperature and blood flow of men in Antarctica.

Alterations to the finger skin temperature (Tsk) and blood flow (FBF) before and after cold immersion on exposure to an Antarctic environment for 8 weeks were studied in 64 subjects. There was a significant fall in Tsk and increase in finger blood flow after 1 week of Antarctic exposure. The Tsk did not further change even after 8 weeks of stay in Antarctica but a significant increase in FBF was obtained after 8 weeks. The cold immersion test was performed at non-Antarctic and Antarctic conditions by immersing the hand for 2 min in 0-4 degrees C cold water. In the non-Antarctic environment the Tsk and FBF dropped significantly (P < 0.001) indicating a vasoconstriction response. Interestingly after 8 weeks of stay in Antarctic conditions, the skin temperature dropped (P < 0.001) but the cold induced fall in FBF was inhibited. Based on these observations it may be hypothesized that continuous cold exposure in Antarctica results in vasodilatation, which overrides the stronger vasoactive response of acute cold exposure and thus prevents cold injuries.

Elastomechanical characterization of brain tissues.

The fluid-induced changes in the intracranial pressure which have important clinical implications are believed to be largely determined by the elastomechanical properties of the brain tissues. To define and evaluate the elastomechanical characteristics of the brain tissues a nonlinear hyperelastic hollow spherical shell has been employed to model the craniospinal complex for its fluid-induced intracranial pressure volume changes. The strain energy function proposed by Hart-Smith has been used to derive the constitutive equations. In 10 dogs, fluid has been infused in the lateral ventricle of the brain. The resulting changes in the ventricular fluid pressure (VFP) and the epidural pressure (EDP) have been recorded. The plot of pressure as a function of volume increases first, reaches a maximum, decreases, reaches a minimum and increases monotonously. The values of maximum and minimum pressures (pv max and pv min) due to fluid infusion are found to be, respectively, 42.4 +/- 15.4 mmHg and 33.1 +/- 12.2 mmHg. The pressure achieved the maximum and minimum values with infusion of 0.19 +/- 0.09 ml and 0.51 +/- 0.15 ml of fluid, respectively. The elastomechanical parameters of the Hart-Smith function that characterize the brain tissues have been evaluated by matching the experimentally obtained pressure-volume curves with the corresponding model generated curves. It is found that the agreement between the experimentally obtained pressure-volume curves and the corresponding Hart-Smith profile is satisfactory at a high inflation level but less so at the lower inflation level.

Relation between epidural and ventricular pressures in canine brain: an experimental study.

Complications of epidural pressure (EDP) monitoring are much less severe than those of ventricular fluid pressure (VFP) monitoring. Hence, an insight into the relationship between the epidural and the ventricular pressures is of clinical importance. The pressure volume response as obtained during infusion tests performed on dogs can be categorized into two phases: (i) the latent phase and (ii) the monotonic rise phase. During the latent phase the VFP first rises to a maximum and then falls to a minimum, but these changes in VFP are not reflected in EDP. The latent phase is followed by the monotonic rise phase during which both VFP and EDP rise simultaneously and monotonically. Although the changes in VFP and EDP are similar the epidural pressure remains consistently less than the ventricular fluid pressure. Hence, changes in VFP can be estimated by monitoring EDP during the monotonic rise phase but not during the latent phase.

Intracranial pressure-volume response in dog subjected to repeated infusion tests: an experimental study.

Several experimental studies have been made in the past to try to understand the nature of the fluid-induced changes in the intracranial pressures of the animals by infusing fluid into their craniospinal complex. The objective of the present investigation was to study the changes in the characteristics of the ventricular and epidural pressure-volume curves when a dog was subjected to repeated fluid infusion tests. The animals were subjected to three cycles of infusion tests with a time interval of either 10 min or 2 h between any two successive tests. An infusion test repeated 10 min after the preceding test exhibited a significant change in the characteristics of the ventricular fluid pressure (VFP) response but not in the epidural pressure (EDP) response. However, in the case of an infusion test which was repeated 2 h after the preceding test, it was observed that both the VFP and EDP responses remained the same as those found in the first infusion test.

REM sleep deprivation and food intake.

The effect of REM-sleep deprivation (REM-SD) on diet preference was studied in rats. REM-SD for a period of 72 hrs produced an increase in day, night and 24 hrs (day plus night) intakes of Carbohydrate Rich diet (CRD) and Total diet (TD). Body weight (BWt) was also increased. The maximum increase in the above parameters were recorded on the 2nd day of REM-SD. During recovery period the intakes of TD fully recovered, but the BWt and consumption of CRD remained high. Intakes of Balanced diet (BD) remained significantly on the lower side when compared to the pre REM-SD mean values. During REM-SD, the rats preferred CRD than BD. The body temperature did not show any change. The increase in TD intake and BWt could be the result of an increase in insulin level and the change appears to be mediated by the activation of hypothalamic feeding centre.