Relationship of possible stress-related biochemical markers to oxidative/antioxidative status in obsessive-compulsive disorder.

Free radicals have been found to play an important role in obsessive-compulsive disorder (OCD). So, we measured the oxidative/antioxidative status of OCD patients, and assessed its use as a biological marker. The study was carried out on 20 healthy and 20 OCD subjects, aged between 20 and 40 years. Biochemical parameters of all subjects were assessed and compared. A significant difference in superoxide dismutase (SOD) levels was observed between the OCD and control groups (p < 0.05); malondialdehyde (MDA) levels were also significantly higher in OCD subjects (p < 0.05). Our study found an overall oxidative imbalance in OCD, leaning towards the antioxidant side in sufferers (specifically towards SOD). SOD has a protective role in overcoming oxidative stress; therefore, oxidative stress could have a pathophysiological role in OCD. Therapy specifically targeting MDA production will have a beneficial effect in overcoming the oxidative stress, anxiety and affective disorder which may be associated with OCD.

Correlation of autonomic indices with thyroid status.

The autonomic status in female thyroid patients was compared with healthy, age matched normal females taken as controls. The patients (29 +/- 7 years) were categorised into two groups: hyperthyroid and hypothyroid. The valsalva manoeuvre, standing to lying ratio (S/L ratio) and immediate heart rate response to standing (30:15 ratio) to assess the parasympathetic status while the galvanic skin response (GSR) was recorded to assess the sympathetic status. Statistical analysis was done using Student's t-test for comparing between the different groups and regression analysis were performed between autonomic indices and thyroid hormone levels. Although the mean values were not significantly different in hypothyroid and hyperthyroid patients, yet the correlation between autonomic function and thyroid hormone levels indicates a statistically significant difference (P-value<0.05), with the S/L ratio. The correlation was negative for log [T3] and log [T4], while it was positive for log [TSH]. This indicates that there is decreased parasympathetic activity with increased T3 and T4, which is in agreement earlier reports. The GSR, which is one of the measures of sympathetic activity, was found to be unaffected.

Task related changes in ERP auditory vs visual tasks.

P3 component of event related potentials have been studied in relaxed state of mind. Changes in P3 latency and amplitude are expected if measured after a rigorous mental exercise. The event related potentials (ERP) were measured in 20 normal male subjects aged between 18 and 22 years. ERP was recorded twice in each subject before and after the administration of a mental task. The auditory mental task comprised of repeating in reverse order string of random digits read out to the subject at a uniform speed of 1 per second. The visual task comprised reading laterally inverted type written text. Each subject had to undergo 2 sessions in separate sittings. The latency and amplitude of P300 recorded before and after the task were compared statistically using Students' unpaired t-test. There was significant increase in P3 latency following both visual and auditory tasks (auditory task: before 330 +/- 24.43 msec and after 342.9 +/- 27.66 msec, similarly visual task: before 333.2 +/- 26.66 msec and after 345.65 +/- 26.56 msec). All other ERP waves latency and amplitude changes were insignificant.

Shifts in information processing level: the speed theory of intelligence revisited.

A hypothesis is proposed here to reconcile the inconsistencies observed in the IQ-P3 latency relation. The hypothesis stems from the observation that task-induced increase in P3 latency correlates positively with IQ scores. It is hypothesised that: (a) there are several parallel information processing pathways of varying complexity which are associated with the generation of P3 waves of varying latencies; (b) with increasing workload, there is a shift in the 'information processing level' through progressive recruitment of more complex polysynaptic pathways with greater processing power and inhibition of the oligosynaptic pathways; (c) high-IQ subjects have a greater reserve of higher level processing pathways; (d) a given 'task-load' imposes a greater 'mental workload' in subjects with lower IQ than in those with higher IQ. According to this hypothesis, a meaningful comparison of the P3 correlates of IQ is possible only when the information processing level is pushed to its limits.

Involving students in question writing: a unique feedback with fringe benefits.

A contest on question writing was organized during the undergraduate medical physiology teaching program. Students were asked to write and submit multiple-choice questions of the assertion-reasoning type (type E) in physiology. The winners were decided after the questions submitted were graded on a six-point scale (0-5) that considered both thematic novelty and construct correctness. Of the 100 students in the class, 37 participated in the contest, and a total of 912 questions was received. The contest encouraged the students to go through their subjects critically. The questions provided the instructor with insight into the learning habits and misconceptions of the students and provided the grist for animated discussions in tutorial classes. Although several types of errors were deciphered in these questions, with suitable modifications the questions helped the faculty build up a sizable question bank.

POST-TASK EVENT-RELATED-POTENTIAL (ERP) CORRELATES OF PSYCHOMETRIC INTELLIGENCE.

The standard psychometric scores show a fair degree of correlation with event-related evoked potential (ERP) latencies and amplitude. Since, both latency and amplitude are known to change during mental activity, it becomes important to consider both pre- and post-task ERP parameters is such correlative studies. In the present study, we have compared the psychometric scores obtained through WAIS-PR with evoked potential latencies and amplitude recorded at 2 sessions, one before, and the other immediately after a brief period of rigorous mental task. A negative corrrelation (-0.4) was found between the IQ of a subject and his P300 latency. Moreover, there was a positive correlation (+0.4) between the IQ of a subject and the latency changes of his P300 following mental exercise (post-task P300 latency minus pre-task P300 latency). Hence, there appears to be a reserve in 'latency increase' proportional to the IQ, which is manifest only following a mental task.

Using simple animations in physiology teaching: ventilatory patterns. A case in point.

Constructing diagrams to explain certain physiological concepts can be challenging. There is a whole class of physiological topics, represented here by the neural generation of respiratory rhythm, that are best taught using "dynamic diagrams," a series of diagrams generated through simple animations and based on user-provided inputs. The theory of neural generation of respiratory rhythm discussed here is not necessarily correct or widely read accepted. It continues to find a place, however, in some of the most widely read textbooks of physiology, which obligates the teacher to devise effective methods of putting it across to the students. Selected criteria can be defined for identifying areas in which dynamic diagrams would be effective as a teaching tool. Unlike those animations that are used to provide a debatable alternative to wet laboratory, dynamic diagrams explaining certain theoretical concepts should have few rivals.

Effect of aminophylline on muscle fatigue.

The effects of two different concentrations of aminophylline, 50 microM/L and 500 microM/L on muscle fatiguability were tested using frog gastrocnemius-sciatic preparations. Two stimulation protocols, one high energy demand, and the other low energy demand were used to induce muscle fatigue. The indices of fatigue employed were (a) the decrease in peak tetanic contraction, (b) the increase in half-contraction time and (c) the increase in the contraction period in response to a high-energy-demand stimulation protocol of fatigue-induction. At the same time, it prolongs the increase in relaxation50-80 time in response to the same protocol.

Teaching nerve conduction to undergraduates: the "traveling flame" analogy revisited.

A familiar analogy to the propagation of the electric wave in a nerve lies in the burning of a cigarette. This analogy, which has persisted through several editions of popular textbooks of physiology, has never been elaborated beyond a cursory mention. In this article, the analogy is reinvoked and refined to explain the cable properties of nerve, saltatory conduction, and some other factors affecting nerve conduction velocity. Experience in lecture classes and feedback obtained through class tests indicate that the analogy, if suitably elaborated and judiciously applied, can increase the retention of the subject by the students.

Are ventilatory impairments related to early onset and long history of diabetes?

Spirometric measurements were done on 20 elderly patients (average age 49 years) of non-insulin dependent diabetes mellitus with a short history of the presenting complaints (3 months to 1 year) and moderate hyperglycaemia (blood glucose 166.42 +/- 43.58 mg/dl) and were compared with age, height and weight-matched healthy controls. The results showed significant restrictive impairments in ventilation in the diabetic group, indicating that the lung volume reductions in diabetes mellitus may not be contingent upon an early age of onset or a long duration of the disease.

Airway functions in pregnant Indian women.

The airway functions in pregnancy have been widely studied but reports obtained from Western and Indian population show divergence. While the Indian populations show significant changes in total and timed vital capacity (FVC and FEV1), the Western counterparts dismiss such changes as insignificant. Our results show insignificant alteration in airway function and support the results reported for Western population.

A hydrostatic model of membrane potential.

A model based on the elementary principles of hydrostatic and air pressures is proposed for classroom demonstration of some concepts related to membrane potential. The instrument comprises a system of U tubes, pressure gauges, stopcocks, and syringes. Intracellular and extracellular ionic concentrations are represented in the model by the pressure heads of fluid columns in the twin limbs of the U tubes. Membrane channels are simulated by stopcocks interposed at the bends of the U tubes. The Na(+)-K+ pump is represented by the syringes that shunt fluid from one limb of the U tube to the other. The pressure of air trapped above the fluid columns is equivalent to electrical potential.

Effect of thyroxine on taste hedonics in rat.

1. The hedonic response to sweetness was tested in 12 thyroxine treated rats using the method of single-bottle brief-exposure to sweet (saccharin) solution. 2. Consumption of the sweet solution was significantly more following administration of thyroxine than during the control period. 3. The 1-hr consumption of saccharin solution appeared to be more sensitive to thyroxine than the 5-minute consumption.

The oxygen-carrying flask: a representational transform of the oxygen dissociation curve of hemoglobin.

The teaching of oxygen transport by hemoglobin is supported by a graphic depiction of the sigmoid O2 dissociation curve of hemoglobin. However, a reconstruction of the same curve into an alternate paradigm, the "O2-carrying flask," affords a visual demonstration of the significance of its sigmoid shape and the implications of its shifts, which should be useful in elucidating certain aspects of O2 transport to undergraduate students of physiology. This article provides a mathematical justification for the flask design.

Effect of ambient temperature changes in autonomic responses.

Effect of moderate changes in ambient temperature on autonomic activity was studied in male medical students. Autonomic function tests, i.e. Valsalva ratio, standing-to-lying ratio (S/L ratio), cold pressor response (CPR) and resting heart rate were carried out at two different ambient temperatures of 37.45 degrees +/- 0.52 degrees C and 32.54 degrees +/- 0.65 degrees C. At lower ambient temperature, there was decrease in the Valsalva ratio, increase in S/L ratio and lesser augmentation of systolic and diastolic blood pressure in CPR as compared to that at higher ambient temperature, indicating alteration in autonomic response with moderate changes in ambient temperature.

A BASIC program for teaching membrane potential.

A qualitative discourse on membrane potential, albeit simple, may be equivocal at crucial points while a purely mathematical treatise on the subject, for all its exactitude, may be incomprehensible to a student of Physiology. A quasi-quantitative approach has therefore been attempted as a compromise between clarity and exactness. A BASIC program is utilised to compute the stereotype calculations and to give instant displays of the results through figures and graphic animations.