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Biomedical subjects

S K Lal

Publications and source records attributed to S K Lal.

At least 37 records · Page 2Linked to original sources
PubMed1997

Placebo-controlled biofeedback blood pressure effect in hypertensive humans.

The role of biofeedback in blood pressure control remains ill-defined because of nonspecific (placebo) effects, small study numbers, and the technical limitations of continuous pressure feedback. Clarification of its potential is awaited by those seeking a nonpharmacological approach to blood pressure control. This study examines the capability for systolic pressure lowering of 5 mm Hg or more using continuous pressure feedback in a statistical sample of untreated, well-characterized, mildly hypertensive individuals. Subjects were randomized in a double-blind study to active or placebo biofeedback. Placebo consisted of a modified contingency approach, using a partial disguise based on a digital high pass filter with 15 elements. Blood pressure-lowering capability was assessed during two laboratory sessions. Continuous visual feedback resulted in 11 of 28 subjects on active treatment and 12 of 28 on placebo treatment lowering their systolic pressure by 5 mm Hg or more (11 +/- 5.6 and 12 +/- 8.4 mm Hg, respectively; P = NS). Prestudy pressure was well-matched (153 +/- 9/97 +/- 4 and 154 +/- 8/98 +/- 4 mm Hg, respectively). An initial small difference in diurnal profile did not change. These findings indicate that among mildly hypertensive individuals, almost half can lower systolic pressure at will for short periods. This capability is independent of the real or placebo nature of the feedback signal. We conclude that there is no specific short-term biofeedback pressure-lowering capability in hypertensive individuals. Further exploration is needed to determine whether specific components of the placebo effect can be delineated, whether personality characteristics influence the response, and whether further biofeedback training can alter the outcome.

Adult↗
PubMed1996

Experience with roxithromycin in visceral leishmaniasis in north Bihar.

In search of an oral drug for Visceral Leishmaniasis, 54 cases of Kala-azar were treated with roxithromycin, an orally administrable drug at a dose of 300 mg twice daily for 21 days. Thirty-nine (86.7%) were responsive (cured), 11 (28.2%) relapsed. The results appeared equally or even more effective when compared to the sodium antimony gluconate in two recent trials in Kala-azar in almost same demographic pattern. A possible synergistic action of roxithromycin and SAG was explored. Toxicities of SAG and roxithromycin are compared and discussed. Further controlled trials are needed before it can be widely used as first line drug for Indian Kala-azar in the present epidemic.

Administration, Oral↗
PubMed1995

Physiological influences on continuous finger and simultaneous intra-arterial blood pressure.

Because of the clinical and experimental utility of continuous finger blood pressure measurements and the need for accuracy, we tested the performance of a new hydraulic device in 22 consecutive hypertensive subjects during physiological and pharmacological interventions. Ipsilateral brachial intra-arterial pressure was monitored during rest, Valsalva's maneuver, static handgrip, and mental arithmetic and after sublingual glyceryl trinitrate. In excess of 40,000 blood pressure values were analyzed. Average bias (intra-arterial minus finger blood pressure) was 8.2 +/- 17.0 mm Hg (mean +/- SD, P = NS) for systolic and 2.8 +/- 10.4 mm Hg (P = NS) for diastolic pressure. Two-way ANOVA of biases with subject and task factors showed a subject effect (P < .001). Intersubject and intrasubject standard deviations of bias were 13.8 and 9.8 mm Hg systolic and 8.7 and 5.7 diastolic, respectively. Linear drift (millimeters of mercury per minute) of finger pressure was greater (P < .001) for systolic than diastolic pressure during static exercise and math and after glyceryl trinitrate. Coefficients of determination for blood pressure ranged from 0.4 +/- 0.3 to 0.8 +/- 0.3 during the tasks. We conclude that (1) noninvasive finger blood pressure faithfully follows intra-arterial changes but with clinically relevant offsets, (2) this technique is best suited for assessing pressure changes, (3) physiological and pharmacological interventions do not consistently affect finger pressure accuracy, (4) many reports of finger blood pressure measuring devices are based on direct readings obtained with inadequate system response characteristics, and (5) the tested instrument falls short of the standard requirements (bias < or = 5 +/- 8 mm Hg) for devices that measure intermittently.

Aged↗
PubMed1993

A novel approach for isolation and mapping of intron mutations in a ribonucleotide reductase encoding gene (nrdB) of bacteriophage T4 using the white halo plaque phenotype.

The nrdB gene of bacteriophage T4 codes for the small subunit of ribonucleotide reductase and contains a 598 base pair self splicing intron which is closely related to other group I introns of T4 and eukaryotes. The screening, isolation and mapping of the nrbB intron mutations was conducted by the strategic usage of the white halo phenotype exhibited by T4 mutants defective in dhydrofolate reductase or thymidylate synthase. We have isolated 159 hydroxylamine-induced nrdB mutants, determined which mutations are in nrdB by marker rescue with clones of the nrdB gene and have mapped these mutations by marker rescue using subclones of the nrdB intron. Thirty out of the 159 nrdB mutations are in or near the intron. These mutations cluster towards the ends, mainly the 3' end. We have performed deletion mapping to further map mutations in the 3' end of the intron. The mutations map in regions of conserved structural elements, thus supporting secondary structure predictions similar to those of the well studied td intron in the T4 gene coding for thymidylate synthase.

Bacteriophage T4↗
PubMed1993

Continuous, non-invasive volume-clamp blood pressure: determinants of performance.

OBJECTIVE: To test a prototype hydraulic, non-invasive, continuous finger blood pressure monitor based on the volume-clamp principle for procedure-related factors likely to influence precision. DESIGN: The influence of these factors was determined by repeatability of finger blood pressure measurement and the relationship to contralateral arm-cuff blood pressure. METHODS: Repeated blood pressure measurements from three different fingers were made in 60 subjects following re-initialization of the device and re-insertion of the finger into the cuff. Repeatability was assessed in relation to simultaneous arm-cuff readings. Drift in arm-finger discrepancy was measured over a 1-h period. Finger diameter, drug therapy and presence of peripheral vascular disease were correlated with arm-finger blood pressure difference. RESULTS: Repeatability coefficients (twice the SD of the arm-finger difference) across device re-initialization were large, but similar to parallel repeated arm blood pressure determinations: 17.6 and 17.1 mmHg for systolic blood pressure (SBP) and 13.9 and 13.6 mmHg for diastolic blood pressure (DBP), respectively. Withdrawing and re-inserting the finger reduced repeatability substantially, with a 50% increase in repeatability coefficient. A trend towards a progressive 9-mmHg increase was observed in overestimation of SBP over the 1-h period. Mean +/- SD pooled arm-finger blood pressure differences were -10.8 +/- 14.6 mmHg for SBP and 4.5 +/- 9.4 mmHg for DBP. Blood pressure measured in different fingers was similar on average, with repeatability no poorer than for re-insertion of the same finger. The presence of peripheral vascular disease in 15 subjects correlated with a smaller arm-finger difference for DBP. CONCLUSIONS: Variations in positioning of the finger within the cuff influences blood pressure measurement during volume-clamp plethysmography, reducing its precision. Finger SBP exceeds brachial auscultatory readings and has similar precision.

Adult↗
PubMed1991

Characterization of a maize cDNA that complements an enolase-deficient mutant of Escherichia coli.

A cDNA encoding maize enolase (2-phospho-D-glycerate hydrolase) was purified by functional genetic complementation using an enolase deficient mutant of Escherichia coli, DF261. This cDNA, pZM245, was characterized by restriction mapping and DNA sequence analysis. The cDNA contained an open reading frame encoding a protein of 446 amino acids with a high degree of similarity to enolase sequences from other organisms (72% identity to yeast enolase and 82% identity to human enolase). The pZM245 contains a correctly positioned consensus prokaryotic translation initiation sequence. The specific activity of enolase in maize increases to about twice its initial level after 48 hours of anaerobiosis. Northern-blot analysis showed a five-fold anaerobic induction in enolase mRNA, while heat shock or cold shock increased enolase mRNA levels only slightly. Southern-blot analysis of maize genomic DNA indicated that there is one copy of the pZM245 hybridizing sequence per haploid genome in maize.

Amino Acid Sequence↗
PubMed1985

Methylene blue and organised differentiation in the chick embryo.

The sub-blastodermal administration of methylene blue at 17 h of incubation gives rise to a mosaic of neuroectodermal differentiation with a disruption of the neural axis at 40 h of incubation. These features appear to be due to the rapid and direct movement of this dye into all the cells of the chick embryo blastoderm, and its binding and breakdown of the cytoplasmic ribose nucleotides, due to which neural tube formation is completely inhibited. The findings are confirmed by combined copper sulphate and methylene blue treatment, as copper is a powerful catalyst of methylene blue activity and binds with RNA.

Animals↗
PubMed1984

The role of transcription in primary induction.

The present study shows that transcription is responsible for primary induction. Areas which have been already induced continue to differentiate and proliferate. From this it is evident that actinomycin D acts on Hensen's node and does not pass into the induced areas. On comparing the initial 17 hours differentiation and the 40 hours development it is evident that induction starts in the middle of the axis when Hensen's node matures, so that the anterior region of the axis. i.e., the brain, is induced both during elongation and regression of the primitive streak. The spinal region is induced only during the regression of the primitive streak.

Animals↗
PubMed1982

The effect of ascorbic acid on a proliferating cell system.

Ascorbic acid, alone and in combination with copper sulphate, was injected into the sub-blastodermal space in the early chick embryo at 17 hours of incubation. There was a marked stunting of the embryonal axis. The absence of interphase cells indicate that ascorbic acid is lethal to the resting cell and results in a reversal of differentiation. Copper counteracts the effect of ascorbic acid and protects the blastoderm when given before ascorbic acid. A parallel action in neoplasia is of importance in the therapeutic use of this vitamin.

Animals↗
PubMed1976

Effect of subdiaphragmatic vagotomy on production of gastric ulcers in pylorus-ligated albino rats.

A reduction in volume and free and total acidity of gastric content was noted along with reduction in ulcer index, with a shift of the site of ulceration from fundus to the glandular part of the stomach, following vagotomy in pylorus-ligated rats. Low volume and acidity explains the absence of ulcers in the fundus, but the increased involvement of glandular part in ulceration is possibly due to weakening of the mucosal barrier following vagotomy.

Animals↗
PubMed1976

Variations of some plasma components after closed fractures.

1) Variations in the serum concentrations of total proteins and the electrophoretic fractions, glycoprotein, mucoprotein, fibrinogen, erythrocyte sedimentation rate, calcium, phosphorus, alkaline, and acid phosphatases were analyzed until the 30th day following uncomplicated fracture of shafts of long bones of the limbs in 25 cases. 2) A significant fall of albumin with concomitant rise of alpha 1, alpha 2, and beta globulins were noted until 30th day. 3) Mucoprotein, glycoprotein, and fibrinogen showed parallel elevations with that of alpha and beta globulins. 4) The peak values of alpha 1 and alpha 2 globulins, mucoprotein, and fibrinogen were registered on the 10th day after trauma. Albumin showed maximum fall on the 10th day in all these cases. 5) Glycoprotein showed a peak value on the 5th day. 6) Total protein and gamma globulin remained almost unchanged throughout the studies. 7) Beta globulin showed higher values and paralleled more closely the fibrinogen and erythrocyte sedementation rates. 8) The elevations of beta globulin, fibrinogen, and erythrocyte sedimentation rate were higher, and persisted beyond 30 days in lower-limb fractures as compared to upper-limb fractures. 9) Serum calcium, phosphorus, alkaline phosphatase, and acid phosphatase were not significantly different following fractures and therefore did not reflect much physiologic variation. 10) The most significant changes in the levels of plasma fractions studied were conspicuous on the 10th day and lasted for about 1 month.

Acid Phosphatase↗