Effect of Menstrual Cycle in Long Latency Reflex of Abductor Pollicis Brevis Among Healthy Female Volunteers.

Background: Long Latency Reflex (LLR) is one of the late responses occurring after H reflex from a mixed nerve by submaximal stimulation. LLR has been found to be absent in patients with multiple sclerosis, spastic patients and in Huntington’s disease. A change in body temperature affects conduction velocity. It is a known fact that there is a change in body temperature during menstrual cycle. However, no studies are available to indicate changes in latency of LLR during the menstrual cycle. Aim: To determine the effect of menstrual cycle on Long Latency Reflex of Abductor Pollicis Brevis among healthy female volunteers. Material and Methods: A cross sectional study was carried out in 30 healthy female volunteers aged 20-30 yrs. The study was conducted between 9.00 a.m.-11.00 a.m using Digital Nerve Conduction/EMG/EP machine (Recorders Medicare system, India) in a laboratory maintained at 22º±3ºC. LLR was recorded during early follicular and mid-luteal phases by stimulation of median nerve while abducting the thumb and recording the EMG response of Abductor Pollicis Brevis. Body temperature was recorded. Latency of LLR obtained during two phases of menstrual cycle was compared. Result: The mean value of latency for LLR was 45.45±2.95 ms (mean±SD) in the mid luteal phase. It was significantly (Wilcoxon test, p<0.001) shorter than the value in the early follicular phase 47.10±2.51ms (mean±SD). This is possibly due to the higher body temperature in the mid luteal phase. Conclusion: Long Latency Reflex was found to be affected during the phases of the menstrual cycle in healthy female volunteers.

The Effect of Phase of Menstrual Cycle on Sympathetic Skin Response Among Healthy Young Indian Women.

This descriptive study was undertaken to investigate the influence of menstrual cycle on sympathetic skin response (SSR) during different phases of menstrual cycle in young healthy Indian women. A comparison of SSR latencies and amplitudes were done in the follicular, ovulatory and mid luteal phases of menstrual cycle. Fifty women in age group of 18 – 25 years having regular menstrual cycles were chosen for this study. After confirming the regularity of menstrual cycle, SSR was performed on them. The recording was done under standardized conditions using standardized procedure. Amplitude of SSR was found to vary in the three phases, but the differences were statistically not significant. Latency of SSR was found to be greatest in the follicular phase (1.54 ± 0.22 s) and least in the mid-luteal phase (1.35 ± 0.18 s). Statistically significant differences were found between mean SSR latency in the follicular phase and the other two phases (p < 0.01). This study concludes that SSR is enhanced during the mid-luteal phase in women with regular menstrual cycles indicating sympathetic dominance.

Electrophysiological changes in acute guillain-barre syndrome.

Aim: To study the various electrophysiological changes in the motor conduction, sensory conduction and F wave latencies of acute Guillain-Barre Syndrome patients. Methods: Sixteen patients with acute GBS were included in this study. They were subjected to various nerve conduction studies (NCS) following standardized procedures. The mean values obtained for the various nerve conduction parameters were compared against the corresponding standardized values using Student’s t-test. P value less that 0.05 was considered significant. Results: The results of NCS in GBS patients were as follows: 1.The motor nerve conduction velocity was significantly lower and the motor nerve conduction latency was significantly prolonged. 2. The sensory nerve action potential conduction velocity and amplitude remained normal in most of these individuals. 3. F wave latency was significantly prolonged. Conclusion: Acute Guillain-Barre Syndrome patients manifest with abnormal motor nerve conduction parameters and F wave latency. Electrophysiological studies would help the researchers to diagnose the disease at an early stage.

Effect of pranayam training on cardiac function in normal young volunteers.

Systolic time intervals (STI) are non-invasive and sensitive tests for measuring the ventricular performance. It has been reported that practice of pranayam modulates cardiac autonomic status and improves cardio-respiratory functions. Keeping this in view, the present study was designed to determine whether pranayam training has any effect on ventricular performance as measured by STI and cardiac autonomic function tests (AFT). Twenty four school children were randomly divided into two groups of twelve each. Group I (pranayam group) subjects were given training in nadishuddhi, mukh-bhastrika, pranav and savitri pranayams and practiced the same for 20 minutes daily for a duration of 3 months. Group II (control group) subjects were not given any pranayam training. STI (QS2, LVET and PEP) and AFT (RRIV and QT/QS2) were measured in both the groups at the beginning and again at the end of three months study period. Pranayam training produced an increase in RRIV and a decrease in QT/QS2, suggesting an enhanced parasympathetic and blunted sympathetic activity respectively. QS2, PEP and PEP/LVET increased significantly, whereas LVET was reduced significantly in pranayam group. In contrast, the changes in STI and AFT were much less marked in the control group. Our study shows that three months of pranayam training modulates ventricular performance by increasing parasympathetic activity and decreasing sympathetic activity. Further studies on a larger sample size may illustrate the underlying mechanism(s) involved in this alteration.

Modulation of cold pressor-induced stress by shavasan in normal adult volunteers.

Shavasan is known to enhance one's ability to combat stressful situations. The present study was planned to determine if shavasan could modulate the physiological response to stress induced by cold pressor test (CPT) and the possible mechanisms involved. Ten normal adults were taught shavasan and practiced the same for a total duration of seven days. RR interval variation (RRIV), deep breathing difference (DBD), and heart rate, blood pressure & rate-pressure-product (RPP) response to CPT were measured before and immediately after shavasan. Shavasan produced a significant increase in DBD and an appreciable but statistically insignificant increase in RRIV suggesting an enhanced parasympathetic activity. Significant blunting of cold pressor-induced increase in heart rate, blood pressure and RPP by shavasan was seen during and even five minutes after CPT suggesting that shavasan reduces the load on the heart by blunting the sympathetic response. It is concluded that shavasan can enhance one's ability to withstand stress induced by CPT and this ability can be achieved even with seven days of shavasan training.

Influence of respiration on human sympathetic skin response.

Sympathetic skin response (SSR) is a reflexly elicited potential of the sweat glands, the afferent and efferent fibres of the reflex are cutaneous sensory fibres (if the SSR is elicited by electrical stimulus) and sympathetic sudomotor fibres respectively. Our earlier study indicated that latency, besides duration and amplitude, of SSR of a given normal individual showed significant variations between many trials of stimulation, even in a single sitting. Since deep inspiration is also an effective stimulus to elicite SSR, the present study was conducted to assess the influence of respiration on SSR. Thirty-four healthy students participated in the study. The skin of the forearm of the dominant hand was stimulated by electrical square pulse and SSR was recorded from the ipsilateral hand. SSR was elicited and recorded in each subject during the various phases of respiration, namely, end expiration (EE), end inspiration (EI), mid expiration (ME) and mid inspiration (MI). It was observed that the mean values of SSR latency during these respiratory phases (EE : 1.59, EI: 1.51, ME : 1.55, and MI: 1.56 sec) were similar, indicating that the normal respiration might not be responsible for the observed interstimulation variations in latency in any given individual.

Effect of different feeding schedules on food intake in caudate lesioned rats.

Inbred albino rats were exposed to different feeding schedules before and after caudate nucleus lesions. The animals show adaptation to the new patterns of food deprivation even after caudate nucleus lesions. However, the lesioned animals are not able to elevate their food intake or body weight to the prelesion levels. These findings suggest that feeding, satiety and body weight mechanisms are disturbed in the absence of intact caudate nucleus, possibly due to removal of nigro-striatal dopamine influence.

Effect of yoga training on reaction time, respiratory endurance and muscle strength.

There is evidence that the practice of yoga improves physical and mental performance. The present investigation was undertaken to study the effect of yoga training on visual and auditory reaction times (RTs), maximum expiratory pressure (MEP), maximum inspiratory pressure (MIP), 40 mmHg test, breath holding time after expiration (BHTexp), breath holding time after inspiration (BHTinsp), and hand grip strength (HGS). Twenty seven student volunteers were given yoga training for 12 weeks. There was a significant (P < 0.001) decrease in visual RT (from 270.0 +/- 6.20 (SE) to 224.81 +/- 5.76 ms) as well as auditory RT (from 194.18 +/- 6.00 to 157.33 +/- 4.85 ms). MEP increased from 92.61 +/- 9.04 to 126.46 +/- 10.75 mmHg, while MIP increased from 72.23 +/- 6.45 to 90.92 +/- 6.03 mmHg, both these changes being statistically significant (P < 0.05). 40 mmHg test and HGS increased significantly (P < 0.001) from 36.57 +/- 2.04 to 53.36 +/- 3.95 s and 13.78 +/- 0.58 to 16.67 +/- 0.49 kg respectively. BHTexp increased from 32.15 +/- 1.41 to 44.53 +/- 3.78s (P < 0.01) and BHTinsp increased from 63.69 +/- 5.38 to 89.07 +/- 9.61 s (P < 0.05). Our results show that yoga practice for 12 weeks results in significant reduction in visual and auditory RTs and significant increase in respiratory pressures, breath holding times and HGS.

Effects of undernutrition and sex difference on skeletal muscle function in young rats.

The effects of undernutrition and sex difference on skeletal muscle contractile characteristics were studied in young albino rats. The skeletal muscle (gastrocnemius) of 8 week old pups with only one-third normal food intake (undernourished group = UN group; n = 18), as compared to free fed pups (control group = cont. group; n = 16), showed prolongation of contraction time (23.6 +/- 1.0 Vs 20.9 +/- 0.8 msec, Mean +/- SE, P < 0.05) and relaxation time (31.5 +/- 1.8 Vs 22.9 +/- 1.1 msec, P < 0.001) and retention of contraction force and endurance time. In 18 week old rats the effects of sex difference in females (n = 10), as compared to males (n = 10) were prolongation of contraction time in gastrocnemius (32.2 +/- 1.5 Vs 27.8 +/- 1.5 msec, P < 0.05), less force production in gastrocnemius (668.9 +/- 48.0 Vs 895.4 +/- 93.3 g, P < 0.05) and extensor digitorum longus (20.1 +/- 3.3 Vs 29.9 +/- 2.5 g, P < 0.05) and shorter endurance time (160.8 +/- 10.2 Vs 187.2 +/- 7.1 sec, P < 0.05) in soleus. Thus, it is concluded that early undernutrition has prolonged the contraction and relaxation times of the skeletal muscles and the effect of sex difference in the early adulthood was different in different skeletal muscles.

Effect of head-up tilting on systolic time intervals in normal young volunteers.

Systolic time intervals (STI) are sensitive indices of myocardial function. Passive tilting is a rapidly reversible and non-invasive method for inducing cardiovascular stress. The present work was conducted to study the effect of graded head-up tilt (HUT) on STI. 20 male medical students were subjected to 30 degrees, 60 degrees and 80 degrees HUT on a tilting table. ECG, phonocardiogram and carotid pulse were recorded simultaneously on Grass polygraph. Electromechanical systole (QS2), left ventricular ejection time (LVET), pre-ejection period (PEP), PEP/LEVT ratio, heart rate (HR) and corrected STI were determined immediately after and at 1, 2, 3, 4 and 5 min after each angle tilt. HUT produced a decrease in QS2 which was more pronounced at higher angle tilt. LVET decreased after 60 degrees and 80 degrees HUT. PEP and PEP/LVET ratio decreased after each angle tilt. These changes in STI can be explained on the basis of sympathetic stimulation-induced increase in the inotropic state of the heart.

A membrane-free plethysmograph for recording volume changes including microlitres.

A method of plethysmography which does not require an air/water tight chamber is described. The method is sensitive enough to record microlitre volumes/volume changes. Its application in two situations, viz. in experimental (artificial) edema and blood flow measurement in the human hand has been demonstrated.

Electrophysiological studies on human phrenic nerve & diaphragm.

To determine normal values for phrenic nerve stimulation, the phrenic nerve was stimulated transcutaneously in 22 healthy adolescent male volunteers. The phrenic latency, amplitude and duration of the evoked diaphragm action potential (EDAP) were noted. Maximum mouth inspiratory pressure (MMIP) and maximum ventilation volume (MVV) were also measured to evaluate the maximal strength of the diaphragm. No significant correlations were observed between EDAP and the parameters of diaphragm strength. The correlation coefficient between the amplitude-duration product of EDAP (integral EDAP) and MMIP was +0.15 and it was +0.29 between the integral EDAP and MVV.

Effect of altered ventilations on human spinal and supra spinal reflexes.

The present study was aimed at evaluating the alterations in the human reflexes brought about by briefly altered ventilations. In 20 healthy young male volunteers, the H reflex and blink reflex were studied during normal ventilation, voluntary hypoventilation and voluntary hyperventilation. The latencies of these reflexes were compared. It was observed that the amount of altered ventilations used in the present study could not produce any significant change in these reflexes except in the case of the early response of the blink reflex.

Effects of central administration of insulin in normal and VMH (ventromedial hypothalamus) lesioned rats on food intake.

Central effects of insulin on 20 min. food intake were studied in rats. Insulin administration in the lateral ventricular cerebrospinal fluid (CSF) did not alter food intake in the intact or lesioned ventromedial hypothalamus (VMH) rats. Whereas, after insulin injection in VMH there was a decrease in food intake. In VMH lesioned rats, subcutaneous injection of insulin increased food intake.

The standardized distal motor latencies and the peak to peak amplitudes of evoked muscle action potentials in the extremities of humans.

The values of Standardized Distal Motor Latency (SDML) of Median, Ulnar and Common Peroneal nerves and the peak to peak amplitude of Evoked Muscle Action Potentials (EMAP) of the small muscles of the limbs were studied in 50 normal subjects. The SDML values showed significant sex difference, whereas no sex difference was observed in the amplitude of the EMAPs.

Myoelectric activity of gastric antrum and jejunum in anaesthetised guinea pigs.

The myoelectric activity of gastric antrum and jejunum was recorded in anaesthetised guinea pigs with Ag-AgCl electrodes. The investigation demonstrated the presence of slow waves and spike potentials. The variability in the pattern of myoelectric activity observed in our study might be due to anaesthesia.

Preliminary studies on the toxicity and mutagenicity of 1-amino-2-naphthol-4-sulphonic acid in Drosophila melanogaster.

The toxicity and mutagenicity of 1-amino-2-naphtho-4- sulphonic acid were analysed in Drosphila melanogaster. Rate of development and viability were the two parameters employed to study the toxicity. The frequency of dominant lethals was scored to evaluate the mutagenic effect of the chemical on male and female germ cells. Concentrations of 250 mg and above/100 ml wheat cream agar medium were found to be significantly toxic. Significant number of dominant lethals was induced even by a concentration as low as 50 mg/100 ml medium. Male germ cells were more sensitive than female germ cells. Keywords. 1-Amino-2-naphtho-4-sulphonic acid;