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Biomedical subjects

S Nath

Publications and source records attributed to S Nath.

At least 19 recordsLinked to original sources
PubMed1992

Adenosine and verapamil-sensitive ventricular tachycardia originating from the left ventricle: radiofrequency catheter ablation.

A ventricular tachycardia (VT) with right bundle branch block (RBBB) QRS morphology and left axis originating from the inferoapical segment of the left ventricle is described in a 49-year-old man without structural heart disease. This VT could be initiated during isoproterenol infusion and was terminated with intravenous administration of adenosine and verapamil. Radiofrequency ablation eliminated the tachycardia. Previous reports have suggested reentry as the mechanism for a verapamil-sensitive VT with this ECG morphology, while cAMP-mediated triggered activity has been proposed as a mechanism for VTs sensitive to adenosine. The latter more typically arise in the right ventricular outflow tract. The electrophysiological and electropharmacological characteristics of the tachycardia in this patient suggest that this VT morphology is not specific for a mechanism but rather for the location of the site of origin.

Adenosine↗
PubMed1992

Carcinoma of penis in Zambia: associated problems in management.

Thirty-three case reports of patients with carcinoma of penis were scrutinised at the University Teaching Hospital, Lusaka, Zambia to look into the associated environmental problems causing an unacceptable level of morbidity and mortality. Due to social and personal reasons, late presentation and poor follow-up is common. Improvement in the poor outcome is only possible with change in social attitudes and alleviation of ignorance. Educating traditional healers will help. For the present radiotherapy may be the other option to improve the morbidity and survival rates in this potentially a curable cancer.

Adult↗
PubMed1991

Reconstitution and partial purification of the Na(+)-selective Na+/H+ antiporter of beef heart mitochondria.

Na+/H+ antiporters play important physiological roles in most biological membranes. Although they were first discovered in mitochondria (Mitchell, P., and Moyle, J. (1969) Eur. J. Biochem. 9, 149-155), the mitochondrial Na+/H+ antiporter has not yet been reconstituted nor has the protein responsible for its activity been identified. We used detergents to extract proteins from beef heart mitochondria and reconstituted these proteins into lipid vesicles loaded with the fluorescent probe, sodium-binding benzofuran isophthalate. The vesicles exhibited spontaneous, electroneutral Na+ transport that was inhibited by Li+ and Mn2+ with appropriate kinetic constants. These protocols were then used to follow fractionation of the solubilized proteins with DEAE-cellulose columns. We obtained a fraction that catalyzed Na+/H+ antiport with Vmax values of 75-120 mumol/mg protein/min, 500-700 times faster than observed in intact mitochondria. Na+ transport was inhibited by Li+ with I50 values of 0.5-1.0 mM and by Mn2+ with I50 value of 0.5 mM. The Km for Na+ was 31 mM. These values correspond to those found in intact mitochondria, and we conclude that the solubilized mitochondrial Na+/H+ antiporter has been partially purified in a reconstitutively active state.

Animals↗
PubMed1991

Cardiopulmonary resuscitation of apparently stillborn infants: survival and long-term outcome.

To determine the outcome of apparently stillborn infants who received cardiopulmonary resuscitation, we studied the short- and long-term outcome of 93 infants who had an Apgar score of 0 at 1 minute of age and were resuscitated at birth. Sixty-two (66.6%) responded and left the delivery room alive; 26 (42%) of the 62 infants died in the neonatal period and 36 infants were discharged home; of the 36 infants, three subsequently died during infancy. Of the 33 survivors, ten were lost to follow-up after discharge. Developmental assessment of 23 of 33 long-term survivors revealed normal outcome in 14 (61.7%), abnormal results in 6 (26%), and suspect status in 3 (13%). Fifty-eight infants had an Apgar score of 0 at greater than or equal to 10 minutes of age and all except one died; the surviving infant has an abnormal developmental outcome. We conclude that 39% of apparently stillborn infants who were resuscitated survived beyond the neonatal period and that 61% of the 23 survivors who were available for developmental follow-up had normal development at the time of last examination. Survival was unlikely if there was no response after 10 minutes of resuscitation.

Apgar Score↗
PubMed1991

A comparative study of the morphology and anatomy of the olfactory organs of two marine fishes with different habitats--Trichiuris savala (Cuv. et Val.) and Tetrodon leopardus (Russel).

The authors carried out a comparative study of olfaction in two marine fishes. The olfactory organs of Trichiuris savala (a middepth feeder) were found to be well developed and capable of detecting smells, whereas in Tetrodon leopardus, which is a bottomfeeder and preferably frequents the sea-bed, the olfactory organs have been secondarily modified to mushroom-shaped bosses.

Animals↗
PubMed1990

Correlation of migration behavior in free-flow zone electrophoresis and electrophoretic titration curve.

The correlation of electrophoretic migration behavior in free-flow zone electrophoresis (FFZE) and electrophoretic titration curve (ETC) has been explored. It is shown that the ETC of a protein or a mixture of proteins can be used to predict the fraction numbers at which those proteins elute in a preparative scale FFZE experiment. The ETC is a quick and effective way to choose optimal buffer conditions in FFZE. FFZE is employed to determine the isoelectric points (pI) of proteins whose pIs lie beyond the range of IEF 3-9 gels. It is found that separations in FFZE are governed by the net surface charge of the proteins.

Buffers↗
PubMed1990

Separation of enzymes from Candida boidinii crude extract by continuous flow zone electrophoresis.

Separation of the enzymes formate dehydrogenase, formaldehyde dehydrogenase and methanol oxidase from Candida boidinii crude extract has been explored using continuous flow zone electrophoresis in the VaP-22 and the scaled-up VaP-220 electrophoresis apparatus. Yields up to 95% and purification factors between 3 and 7 were obtained, together with separation of cell debris from the enzymes. Multiple injections of sample were used to obtain a protein throughput of 46.2 mg/h in the VaP-22. A tenfold higher throughput was achieved using the VaP-220. Correlation of the electrophoretic mobility in continuous flow zone electrophoresis with the elution behavior in ion-exchange chromatography confirmed the primary role of net surface charge in the separation of biological molecules. Proteins and enzymes with differences greater than 0.05 M elution molarities in ion-exchange chromatography can be separated. This corresponds to a preparative scale (mg/h or g/h) separation of proteins and enzymes whose difference in apparent electrophoretic mobility is greater than 0.70 x 10(-5) cm2/(V.s).

Alcohol Oxidoreductases↗
PubMed1990

Use of regression analysis in reconstruction of maximum bone length and living stature from fragmentary measures of the ulna.

The present study deals with the computation of linear and multilinear regression formulae for reconstruction of ulnar length and stature through eleven fregmentary measures pertaining to linear, transverse, sagittal and circumferential dimensions of the ulna bone. A total of 288 ulnae, belonging to 82 male and 62 female documented skeletons have been measured for this purpose. The data reveals a non-significant bilateral variation in the fragmentary measures of the ulna while the sex differences are highly significant at 1% level. Keeping this in view, separate regression equations have been formulated for both the sexes. The study further highlights that the upper shaft circumference is the best predictor of ulnar length among all the fragmentary measures while stature can best be reconstructed using the breadth of olecranon. However, the maximum length as a non-fragmentary measure provides the most accurate estimate. In order to increase the accuracy in prediction of ulnar length and stature, multiple regression equations have also be constructed and used.

Adult↗
PubMed1989

Cardiotoxicity of ropivacaine--a new amide local anaesthetic agent.

Anaesthetically equipotent doses of lidocaine, bupivacaine and a new bupivacaine-like local anaesthetic agent, ropivacaine, were injected into the left anterior descending coronary artery of pentobarbital-anaesthetized pigs. The aim was to study the cardiotoxicity of ropivacaine in relation to the two other drugs. A random, crossover, dose response study design was used. The following doses of the drugs were administered: lidocaine (L): 1,2,4,8 and 16 mg, bupivacaine (B): 0.25, 0.5, 1,2 and 4 mg and ropivacaine (R): 0.33, 0.66 1.33, 2.66 and 5.33 mg. Systemic haemodynamics, left ventricular dP/dT and a 12-lead electrocardiogram were recorded continuously during the study period. The drugs depressed cardiac contractility in relation to their local anaesthetic potency on the isolated nerve-4:3:1 (B:R:L). The prolongation of the ECG QRS-interval was regarded as a measure of electrophysiologic toxicity. Comparable prolongation of the QRS-interval was recorded after 2 mg of bupivacaine, 4.5 mg of ropivacaine and 30 mg of lidocaine. Thus, the electrophysiological toxicity ratio was 15:6.7:1 (B:R:L). Provided local anaesthetic potency data can be extrapolated from the isolated nerve preparation to regional anaesthesia in humans, ropivacaine appears to provide a greater margin of safety than bupivacaine, if inadvertently injected into the venous circulation.

Amides↗
PubMed1988

Pairing alters the effect of progesterone on nesting in female C57BL/10Sn mice.

Progesterone treatments have been shown to increase nesting levels of isolated female mice. Here we compared the effect of exogenous progesterone on the nesting behavior of C57BL/10Sn female Mus domesticus housed individually to nesting levels of the same mice housed in pairs. Progesterone increased nesting by isolated females but had no significant effect on the nesting scores of the same mice when they were grouped into pairs. The effect of exogenous progesterone on nesting levels in C57BL/10Sn females appears to depend on social circumstances.

Animals↗
PubMed1988

Optic pit, microphthalmos and orbital cyst.

An orbital cyst was discovered by ultrasonography behind the globe of the left eye in a five-year-old boy with a left esotropia. In addition, an optic pit was present in the optic nerve head of the same eye, which was microphthalmic relative to the right eye. Although orbital cyst has been reported in the literature, this case is of interest because of the presence of two congenital anomalies in the same eye - namely, optic pit and orbital cyst. These two conditions have never been previously reported as existing together in the same eye.

Child, Preschool↗
PubMed1988

Presurgical prediction of postsurgical visual acuity in patients with media opacities.

Of the estimated 1 million patients each year in the United States who undergo surgery for media opacities, perhaps 5-10% fail to improve because of pre-existing, undiagnosed retinal and/or optic nerve disease. In this paper, the standard presurgical evaluation (case history, visual acuity, refraction, pupillary response testing, biomicroscopy, ophthalmoscopy, tonometry, visual fields and color vision) and the supplementary presurgical evaluation (entoptic phenomena appreciation, ophthalmic ultrasonography, fluorescein angiography, laser interferometry, potential acuity meter, visual evoked potential, electroretinography, contrast sensitivity and hyperacuity measurements) are reviewed.

Cataract↗
PubMed1986

Differential depressant and electrophysiologic cardiotoxicity of local anesthetics: an experimental study with special reference to lidocaine and bupivacaine.

In 15 pigs lidocaine and bupivacaine were injected into the left anterior descending (LAD) coronary artery to investigate the cardiotoxic effects of these drugs. Anesthesia was maintained by a continuous intravenous pentobarbital infusion and ventilation was controlled. Aortic, pulmonary arterial, right atrial, and left ventricular pressures, a standard 12 lead ECG, cardiac output, and great cardiac venous blood flow were recorded. The local anesthetics were administered at body temperature over approximately 10 sec in a random, crossover fashion at the following equipotent anesthetic doses: bupivacaine, 0.25, 0.5, 1, 2, and 4 mg; lidocaine, 1, 2, 4, 8, and 16 mg. The hemodynamic effects were short-lived, peaking about 5 sec after drug infusion. At the highest dose, both drugs decreased left ventricular dP/dT by 28% (P less than 0.001) and aortic blood pressure by 12% (lidocaine) and 8% (bupivacaine) (P less than 0.001 and P less than 0.01). Heart rate, cardiac output, and coronary venous blood flow did not change. Thus, the cardiodepressant ratio between the two drugs was comparable with their local anesthetic the two drugs was comparable with their local anesthetic potency ratio (bupivacaine/lidocaine, 4:1). Seven animals died in ventricular fibrillation within 1 min after 4 mg bupivacaine dose. All animals given 16 mg lidocaine survived. Ventricular fibrillation was preceded by progressive widening of the QRS complexes recorded over the area perfused by the LAD. The ECG changes after 16 mg lidocaine were of the same magnitude as those recorded after 1 mg bupivacaine. In five of the surviving animals 32 and 64 mg lidocaine were injected intracoronarily after termination of the crossover study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Visual evoked potential (VEP) delays in central serous choroidopathy.

The authors examined a series of ten consecutive patients with unilateral, idiopathic central serous choroidopathy. Visual acuities ranged from 20/20 to 20/70 during the active stage. VEPs were recorded to square sizes of 14, 28, and 56 min of arc. Overall, 90% of the patients had statistically significant VEP delays from the affected eye, while only 30% had statistically significant reductions in amplitude during the active stage. Six of the ten patients were reevaluated after the condition fully resolved. In all six, the VEP latency returned to normal. Although the mechanism of these VEP delays is not clear, their presence has been well documented. Therefore, a VEP delay in isolation of other tests should not be used in the differential diagnosis of macular vs optic nerve disease. One should specifically rule out macular disease in any patient with a delayed VEP before presuming the presence of a visual pathway dysfunction.

Adult↗
PubMed1985

Diarrhea associated with typhoid fever.

To study the pathogenesis of diarrhea occurring with typhoid fever, we selected 42 patients with diarrhea and blood cultures positive for Salmonella typhi or Salmonella paratyphi A, but without diarrheal copathogens, for measurement of stool output and examination of fecal composition. The mean duration of fever before hospitalization was 9.5 days, and the mean duration of diarrhea was 5.8 days. All patients passed liquid stool on their first day in the hospital, ranging in volume from 4 to 172 ml/kg with a mean of 45 ml/kg. Red blood cells were in the stools of 57% of the patients. All patients had fecal leukocytes with a mean of 4,950 leukocytes/mm3, predominantly polymorphonuclear leukocytes. In the stools, the mean protein concentration was 9.3 g/liter; the mean pH was 6.1, and the mean concentration of electrolytes was as follows: sodium, 47 mEq/liter; potassium, 48 mEq/liter; and chloride, 43 mEq/liter. The mean total CO2 was 24 mmol/liter. During treatment with chloramphenicol, this group of patients showed daily improvement with a drop in both fever and stool output. The results indicate that patients with diarrhea during typhoid fever have a wide range of rates of purging, and the diarrhea is characterized by liquid stool containing large quantities of leukocytes and protein and is resolved by treatment with chloramphenicol.

Adolescent↗
PubMed1985

Spectrum of advanced upper airway obstruction due to goiters.

Five patients with advanced upper airway obstruction due to goiter were identified in our institution. All had symptoms of respiratory insufficiency to such a degree that surgery was clearly indicated. Functional characteristics of this group were compared with prior series of goiter patients who had less severe respiratory symptoms. A peak inspiratory flow less than 1.5 L/sec characterized this group who required surgery.

Aged↗
PubMed1985

Maturational sequence of growth in transverse dimensions of head, face and trunk among male Jats of North India.

The maturational sequence of growth in the transverse measures of head, face and trunk has been studied on a sample of 500 male Jats of North India, measured cross-sectionally, ranging in age from 10.0 to 19.0 years. This clearly reveals the existence of both cephalo-caudal and caudo-cephalic directions of maturation. The existence of multiple gradients is also observed at different age levels within the head and face measures and also between the cephalo-facial and trunk breadths. Growth has not ceased among Jats of North India by age 19, and a slight increase in the breadths of head, face and trunk is expected beyond 19 years.

Adolescent↗