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Biomedical subjects

R K Marya

Publications and source records attributed to R K Marya.

At least 37 records · Page 2Linked to original sources
PubMed1988

Long latency inhibition of H-reflex recovery by cutaneous tactile stimulation in man: a cutaneous transcortical reflex.

The effect of cutaneous tactile stimulation on motoneuron excitability was studied in 20 normal subjects and in patients of hemiplegia (n = 14) and paraplegia (n = 15) by plotting H-reflex recovery curves during application of twin pulses alone ("basal" H-reflex recovery curve), and twin pulses synchronized with electrical stimuli evoking tactile sensation in skin over the lateral border of the small toe. The "basal" H-reflex recovery curves from normal subjects showed a significant lateral asymmetry of motoneuron excitability, with an even distribution of subjects showing greater excitability on the left and right sides. However, there was no relation between handedness and the side with greater excitability. The cutaneous stimulation produced a highly significant inhibition of the H-reflex recovery between 600 and 6000 ms, with the maximum inhibition recorded at 1000 and 2000 ms, at which time even a complete inhibition of the test H-reflex was observed in some instances. The effect of cutaneous stimulation before 600 ms was statistically insignificant. The amount of cutaneous inhibition of H-reflex recovery showed a lateral asymmetry. The side with greater motoneuron excitability showed more cutaneous inhibition of the H-reflex recovery. A comparison of the H-reflex recovery at higher frequencies of cutaneous stimulation with that at basal frequency showed a slight but statistically insignificant difference in the amount of cutaneous inhibition of the H-reflex recovery. In hemiplegics, the "basal" H-reflex recovery curves showed greater motoneuron excitability on the affected side as compared to those of the unaffected side or controls, with the late inhibitory phase being completely obliterated. A similar pattern was also observed in paraplegics. Significantly, the lateral asymmetry of motoneuron excitability observed in the control group was absent in paraplegics. The cutaneous stimulation failed to produce any significant effect on the H-reflex recovery curves either in the affected side of hemiplegics or in both sides of paraplegics. The significant long latency inhibition of the H-reflex recovery curve produced by cutaneous tactile stimulation is a new finding.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Effect of pregnancy on the lamina dura.

Serum chemistry studies and radiological examination of the lamina dura and phalanges were conducted in 50 pregnant women, 25 of whom had been administered calcium and vitamin D supplements during the 3rd trimester. The non-supplemented pregnant women showed significant hypocalcaemia, elevated serum heat-labile alkaline phosphatase activity, and resorption of the lamina dura. The supplemented group of pregnant women also showed resorption of the lamina dura, although the serum chemistry was essentially normal. It is suggested that, probably because of gestational hyperparathyroidism, mild resorption of the lamina dura may be a feature of normal pregnancy.

Adult↗
PubMed1987

Suprachiasmatic injection of a vasopressin antagonist modifies the circadian rhythm of food intake.

To study the effect on the circadian feeding rhythm, injections of AVP and its antagonist were made into the suprachiasmatic nuclei (SCN) of rats after implanting cannulae into the bilateral SCN. Injections of arginine vasopressin (AVP) antagonist at the beginning of the light and dark phases disrupted the circadian rhythm of food intake while injections of AVP during the beginning of the light or dark phase did not disrupt the circadian rhythm. It may be concluded that endogenous vasopressin has a modulatory role in the mediation of the circadian feeding rhythm at SCN.

Animals↗
PubMed1987

Effect of calcium and vitamin D supplementation on toxaemia of pregnancy.

To study the effect of calcium and vitamin D supplementation on the incidence of toxaemia of pregnancy, 200 randomly selected pregnant women (supplemented group), were put on calcium (375 mg/day) and vitamin D (1,200 IU/day) supplements at 20-24 weeks of pregnancy onwards. Another 200 pregnant women constituted the non-supplemented group. At 32 and 36 weeks of pregnancy the systolic and diastolic blood pressure of non-toxemic women was significantly lower in the supplemented group than in the non-supplemented group. However, the incidence of toxaemia in the supplemented group (6%) was not significantly different from that in the non-supplemented group (9%).

Adult↗
PubMed1987

Urinary calcium excretion in pregnancy.

Urinary calcium excretion and creatinine clearance studies have been conducted in 50 women at 36 weeks of pregnancy and 50 normal controls. Of the pregnant women, 25 had been administered 600,000 IU vitamin D in the 24-26 weeks of pregnancy (supplemented group). The non-supplemented group showed significant hypocalcaemia (even after accounting for low plasma protein levels) and hypocalciuria, while the supplemented group showed normocalcaemia as well as significantly greater 24-hour urinary calcium excretion than the controls. 24-hour creatinine clearance was increased in both groups of pregnant women. It was concluded that, due to increased GFR, urinary calcium excretion tends to increase in pregnancy provided the subject is not deficient in vitamin D. Occurrence of hypocalciuria in pregnancy suggests vitamin D deficiency and should not be considered a physiological adaptation.

Adult↗
PubMed1982

Myoelectrical activity in experimental aganglionosis of the colon in the rat.

Experimental aganglionosis of the colon was produced in rats by an experimental "aganglionosis producing" procedure. Radiological examination of the aganglionic colon showed a narrow segment distal to a dilated megacolon. Histologically, a transverse section of the aganglionic segment showed 3-4 ganglia in contrast to 32-40 ganglia per section in the normal colon. The myoelectrical activity of the normal colon presented two fast activities, a fast activity with a frequency of 25-40 cycles per sec superimposed over a medium-fast activity of 4-7 cycles per sec. However the aganglionic colon showed only the fast activity with complete absence of the medium-fast activity. Thus the experimental aganglionosis produced a characteristic alteration in the myoelectrical activity of colon. This confirms our earlier findings in children with Hirschsprung's disease. It also suggests that the causative mechanism for the production of a narrow segment in Hirschsprung's disease may not be the hyperactivity or the absence of any specific neuronal mechanisms as proposed earlier.

Animals↗
PubMed1981

Concentrations of Calcium, inorganic phosphorus and alkaline phosphatase in the sera of lactating women in North India.

Serum calcium, inorganic phosphorus and alkaline phosphatase (SAP) have been determined in 75 lactating women and 25 controls. 25 lactating women were re-investigated after administration of calcium and vitamin D supplements of 1 month. Lactating women showed statistically significant hypocalcaemia and raised SAP. However, the elevation of the enzyme level was significantly lower in women with milk intakes of more than 1/2 litre per day and in those in later months of lactation. The effects of calcium and vitamin D supplementation supported a diagnosis of osteomalacia in a large percentage of lactating women.

Adult↗
PubMed1981

Genetic predisposition to renal stone disease in the first-degree relatives of stone-formers.

Stone formers, their spouses and first-degree relatives have been investigated for hypercalciuria and crystalluria. The incidence of hypercalciuria was far greater in stone-formers and their first-degree relatives than in their spouses. The urine of the stone-formers and their first-degree relatives contained calcium oxalate crystals in greater number and of larger size than that of the spouses or the controls. It was concluded that the predisposition to renal stone disease was far greater in those who shared the genetic pattern of stone-formers than those who shared their environmental conditions only.

Adult↗
PubMed1981

Effects of vitamin D supplementation in pregnancy.

Serum calcium, inorganic phosphate and heat-labile alkaline phosphatase (HLAP) have been estimated in maternal and cord sera of 120 pregnant women at labour. 75 women who did not take any vitamin D supplements during pregnancy showed statistically significant hypocalcaemia, hypophosphataemia and elevation of HLAP. Hypocalcaemia and hypophosphataemia were present in cord blood, too. 25 women who had received 1,200 U vitamin D/day throughout the 3rd trimester, showed significantly lower HLAP levels and increased fetal birth weight but there was no other improvement in maternal or cord blood chemistry. Administration of vitamin D in two large doses of 600,000 U each in the 7th and 8th months of pregnancy in 20 women proved more efficacious. Statistically significant improvement was observed in all the three biochemical parameters in maternal as well as cord sera. Fetal birth weight was also significantly greater with this mode of therapy.

Birth Weight↗
PubMed1979

Occult anticonvulsant osteomalacia in North India.

Serum calcium, inorganic phosphate and alkaline phosphatase, tubular reabsorption of phosphate (TRP) estimation and radiological examination of the skeleton were conducted in 40 cases (18-50 years of age) on anticonvulsant therapy and 20 controls. The epileptic group showed a statistically significant rise in serum alkaline phosphatase and a fall in TRP. In none of the cases, however, was there clinical or radiological evidence of osteomalacia. Biochemical abnormalities were seen mainly in the youngest individuals. It seems that the critical factor for the development of anticonvulsant osteomalacia is the lack of dietary vitamin D/solar exposure or increased body requirement of the vitamin.

Adolescent↗
PubMed1979

Renal excretion of hydrogen ions in stone formers.

Urinary hydrogen ion excretion has been studied in 68 adult stone formers and in 50 controls. Under basal state, the stone formers showed statistically significant higher urinary pH, and lower 24-hour urinary titrable acid, ammonium and total hydrogen. On the 3rd day of ammonium chloride loading test, the stone formers showed statistically significant higher urinary pH and lower 24-hour urinary titrable acid, ammonium, total hydrogen and plasma bicarbonate. 'Clearance' indices of hydrogen ion excretion were also depressed in a great majority of the stone formers. The results indicate the frequent co-existence of defective urinary acidification with nephrolithiasis.

Adolescent↗