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Biomedical subjects

R Rao

Publications and source records attributed to R Rao.

At least 199 records · Page 11Linked to original sources
PubMed1987

The defective proton-ATPase of uncA mutants of Escherichia coli: ATP-binding and ATP-induced conformational change in mutant alpha-subunits.

Mutations in the uncA gene of Escherichia coli cause loss of both oxidative phosphorylation and ATP-driven generation of the transmembrane proton gradient. The uncA gene encodes the alpha-subunit of the F1-sector of the E. coli membrane proton-ATPase. F1-alpha-subunit from normal (unc+) E. coli binds ATP tightly (KD = 0.1 microM) and undergoes a large ATP-induced conformational change, but the functional role of the ATP-binding site is currently unknown. There is disagreement in the literature as to whether the ATP-binding site is present or lacking in F1-alpha-subunit from uncA mutant strains. One obstacle in studying this question is the difficulty of purifying mutant alpha-subunits in native form. In order to circumvent this difficulty we have studied ATP binding and ATP-induced conformational changes in mixtures of F1 subunits obtained by dissociating uncA mutant F1. Anti-alpha antibody was used in conjunction with immunoblotting to identify the alpha-subunits in the mixtures. Retention of native conformation by the alpha-subunits was demonstrated by the fact that the dissociated alpha-subunits were fully competent to repolymerize with other F1 subunits to yield intact F1 aggregate. The results show that, contrary to previous reports, alpha-subunits from three catalytically defective uncA mutants do indeed bind ATP and do undergo an ATP-induced conformational change. The binding affinity of alpha-subunit for ATP was lower than normal in each of the three mutants, but this is not likely to be a significant factor under physiological conditions.

Adenosine Triphosphate↗
PubMed1986

Yersinia colitis masquerading as pseudomembranous colitis.

We describe a 15-month-old male who presented with fever and diarrhea 24 hr after receiving antibiotics for otitis media. A flexible sigmoidoscopy was initially interpreted endoscopically as antibiotic-associated pseudomembranous colitis, and the patient was treated with vancomycin. The diagnosis of antibiotic-associated colitis was excluded in our patient by the negative stool examination for Clostridium difficile toxin, the failure to obtain supportive features on rectal biopsy, and the failure to demonstrate sigmoidoscopic improvement with vancomycin therapy. Thirteen days later, Y. enterocolitica was cultured from the initial stool specimens. In this case, the raised central whitish area on an erythematous base was misinterpreted as pseudomembranous colitis.

Colitis↗
PubMed1986

Decline in serum calcium, magnesium, and phosphorus values with oral glucose in normal neonates: studies of serum parathyroid hormone and calcitonin.

In 10 normal term infants aged 52 +/- 2.5 hours, serum calcium, magnesium, phosphorus, ionized calcium, parathyroid hormone, and calcitonin were studied at 0, 1/2, 1, and 2 hours after administration of 1.77 +/- 0.08 gm/kg glucose orally over 20 minutes. In response to glucose administration, serum glucose concentration rose and serum P, Ca, and Mg concentrations fell. Serum PTH concentration rose significantly, and blood ionized Ca and pH were unaltered. Serum calcitonin was elevated, as compared with adult values, and did not change. We suggest that in neonates, as in adults, oral ingestion of glucose lowers serum Ca, Mg, and P, and a compensatory rise in serum PTH concentration maintains blood ionized Ca concentration.

Administration, Oral↗
PubMed1986

Luteal phase concentrations of a progestagen-associated endometrial protein (PEP) in the serum of cycling women with adequate or inadequate endometrium.

We previously demonstrated that the human endometrium synthesizes and secretes a specific protein designated "Progestagen-associated Endometrial Protein" or PEP. This work was undertaken to determine luteal phase levels of PEP in serum of cycling women with histologic evidence of adequate endometrium (endometrium in phase) or inadequate endometrium (endometrium out of phase by 3-4 days). The results provide a normative curve with 95% confidence limits for serum PEP concentrations vs normalized cycle day in women with adequate endometrium (judged by histologic endometrial dating), and indicate that the PEP concentration increases exponentially after day 22, with a mean doubling time of 2.95 +/- 1.60 (mean +/- SD) days (based on serial data from 13 women). More importantly, the proportion of serum PEP values falling outside of the 95% confidence limits was significantly greater (p less than 0.001) in women with inadequate endometrium (83%) than in women with adequate endometrium (16%). Therefore, determination of PEP in serum, rather than the more invasive endometrial biopsy examination, may serve as a method of choice for evaluating endometrial adequacy in infertile women.

Endometrium↗
PubMed1986

Functional preservation of the mammalian kidney. VII. Autologous transplantation of dog kidneys after treatment with dimethylsulfoxide (2.8 and 4.2 M).

This research demonstrates that dog kidneys perfused with dimethylsulfoxide (Me2SO) in likely cryoprotective concentrations (2.8 M) can survive as the sole source of renal support when autologously transplanted. Kidneys were perfused in vitro with Me2SO in one of two vehicles: solution A (K+-Mg2+-rich) or RPS-2 (K+-glucose-rich). Me2SO concentration in the vehicle was gradually increased to maximum (2.8 or 4.2 M) over a period of 28 to 35 min, held for 5-10 min, then decreased over 55-65 min. All groups except one consisted of 5 kidneys perfused at 25 degrees C. Survivors were dogs living 21 days postoperatively. The first group received kidneys perfused with solution A; 5 dogs survived, serum creatinine on day 21 [Cr], [mean +/- SE] = 1.3 +/- 0.1. The second group received RPS-2 kidneys; 4 survived, Cr=1.4 +/- 0.1. The third group received solution A kidneys with 2.8 M Me2SO; 3 survived, Cr=2.7 +/- 1.3. The fourth group received RPS-2 kidneys with 2.8 M Me2SO; 5 survived, Cr=1.2 +/- 0.2. The fifth group received RPS-2 kidneys with 4.2 M Me2SO; 2 survived, Cr=1.7 +/- 0.3. One group of 6 dogs received kidneys perfused at 10 degrees C with 4.2 M Me2SO in RPS-2; one survived, Cr=1.4. Results demonstrate beneficial interaction of vehicle with Me2SO and the efficacy of 25 degrees C perfusion.

Animals↗
PubMed1985

Pediatric Hodgkin's disease in India.

Twenty-one percent of all Hodgkin's disease in India was seen in the pediatric age groups at the Tata Memorial Hospital (Bombay, India). From 1975 to 1982, 151 cases of children were reviewed. The youngest presentation was at 3 years in three patients, with a marked male: female ratio of 5.5:1. Twenty-six patients were previously treated before referral while the remaining 125 cases were investigated and treated according to the prevalent protocols in 1975 to 1978 and 1979 to 1982. Clinical staging revealed 54% of patients in stages I and II with symptoms in 20%, and 46% of patients in stages III and IV with symptoms in 67%. Staging laparotomy was performed in 27 patients, with a total changes of staging in 17 children (63%). The mixed cell types (46%) and lymphocytic predominant types (31%) were the most common histologic presentations. Nine percent nodular sclerosis and 9% lymphocytic-depleted varieties were also observed. Five percent of all cases were not classifiable. Minimum adequate treatment was completed in 87 cases. Comparisons were made between the treatments administered to 40 patients during the initial period 1975 to 1978 when individualized treatment was administered, and the later 47 patients during the 1979 to 1982 period, when chemotherapy was the mainstay of treatment with involved field radiation.

Actuarial Analysis↗
PubMed1985

Effect of hypocalcemia on cardiac function in very-low-birth-weight preterm neonates: studies of blood ionized calcium, echocardiography, and cardiac effect of intravenous calcium therapy.

Traditionally, in infants, a serum calcium value less than 7.0 mg/dL is considered to impair cardiac function. In very-low-birth-weight infants, we studied the hypotheses that decline in serum calcium to 6.0 mg/dL (1) would not impair cardiac function and (2) ionized calcium would remain greater than 3.0 mg/dL. We also evaluated the effect of calcium infusion on cardiac function. We studied 15 normokalemic and normonatremic infants whose birth weights were 822 to 1,450 g and were less than 32 weeks' gestation. When serum calcium declined to less than 6.0 mg/dL, 18 mg/kg of calcium as 5% calcium gluconate was infused for 10 minutes. Serum total calcium concentration, blood ionized calcium concentration, ECG, and M-mode echocardiogram were obtained on entry into the study, when the infants were hypocalcemic, immediately after treatment with calcium, and eight hours after treatment. Ionized calcium values were calculated based on serum total calcium and serum protein, and corrected calcium values were calculated based on serum total calcium, serum albumin, and blood pH. In all infants, serum calcium value declined to less than 7.0 and in eight infants to less than 6.0 mg/dL. Assessment of heart rate, systolic blood pressure, ejection fraction, left ventricular systolic time interval, right ventricular systolic time interval, fiber shortening index, and left ventricular mean velocity of circumferential fiber shortening showed no significant alteration from baseline during hypocalcemia or in association with intravenous slow bolus infusion of 18 mg/kg of calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗
PubMed1982

Integrity of central dopaminergic system in women with postpartum hyperprolactinemia.

In order to elucidate the role of elevated prolactin (PRL) on the central dopaminergic systems, the suppressive effects on PRL were studied after the administration of L-dopa and L-dopa plus carbidopa on consecutive days to the following three groups: 10 normoprolactinemic subjects, six nonnursing normal puerperal women, and seven hyperprolactinemic women without any evidence of pituitary tumor. In the normoprolactinemic subjects (basal PRL 13 +/- 2 ng/nl mean +/- SE), the suppressive effects of L-dopa alone and L-dopa plus carbidopa were similar (48% +/- 4% and 58% +/- 6%, respectively). In puerperal hyperprolactinemic subjects, the basal PRL (116.8 +/- 16.4 ng/ml) was suppressed 77% +/- 2% after administration of L-dopa and 51% +/- 7% after L-dopa plus carbidopa, significantly different from that of L-dopa alone (p less than 0.005), but similar to that observed in normal subjects. In the patients with idiopathic hyperprolactinemia, the baseline PRL (131 +/- 38 ng/ml) decreased 56.3% after the administration of L-dopa. In the presence of peripheral dopa decarboxylase inhibition, the administration of L-dopa decreased plasma PRL values 30%, a drop significantly different from that of L-dopa alone (p less than 0.02). Women with idiopathic hyperprolactinemia exhibit reduced central dopaminergic inhibition of PRL secretion similar to that in patients with pituitary tumor; whereas the response to central dopaminergic inhibition in postpartum women with comparable baseline PRL levels is similar to that in normoprolactinemic subjects. This indicates that hyperprolactinemia per se is not associated with a state of reduced central dopaminergic inhibition. The increased pituitary sensitivity to L-dopa observed in puerperal women may be due to alterations in PRL receptors or vascularity.

Carbidopa↗
PubMed1982

The effect of albumin gradients and human serum on the longevity and fertilizing capacity of human spermatozoa in the hamster ova penetration assay.

The motility and the capability to penetrate zona-free hamster eggs of Y-enriched or washed sperm were evaluated after protracted in vitro incubation with and without the addition of preheated human serum. The addition of 50% preheated serum decreased the motility loss over time for both the washed and Y-enriched sperm. Such motility loss was decreased by 25% and 27% at 20 hours, by 31% and 39% at 30 hours, and by 30% and 40% at 40 hours of incubation for the washed and Y-enriched sperm, respectively. The washed and Y-enriched sperm suspensions with and without addition of preheated human serum achieved 100% penetration rate after 2 hours of preincubation. However, when scored by the sperm per egg ratio, washed sperm achieved 1.2 +/- 0.2 (mean +/- standard error [SE]) sperm per egg, while the Y-enriched sperm achieved 3.0 +/- 0.4 sperm per egg. After 24 hours of incubation, penetration by washed sperm decreased to a mean of 62.8%. The Y-enriched sperm penetrated a mean of 18% of the ova. Addition of preheated serum increased the egg penetrating capacity of washed sperm at 24 hours but failed to improve the Y-enriched spermatozoa. This study suggests that for optimum conception rates, precise ovulation timing is crucial when Y-enriched fractions are used for insemination.

Animals↗