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Biomedical subjects

R Rao

Publications and source records attributed to R Rao.

At least 163 records · Page 9Linked to original sources
PubMed1993

Neonatal necrotizing enterocolitis an epidemiological study.

Necrotizing enterocolitis (NEC) was diagnosed in 77 infants among 2200 admissions to the NICU during the period January 1986 to September 1990. The incidence was 0.5% of all live births and 3.5% of NICU admissions. Majority (57.1%) had Stage I of the disease while 23.4% had Stage II and 19.5% had Stage III of the disease. The average birth weight of the babies was 1650 +/- 577 g and gestational age 33.3 +/- 2.6 weeks. Majority (53.2%) were very low birth weight (VLBW) babies. Incidence was significantly more (5.7% vs 0.25%, p < 0.001) in VLBW infants and in preterm infants of gestational age less than 32 weeks (5.2% vs 0.09%, p < 0.001). Multiple risk factors were present in these babies while 8 babies did not have any risk factor. Risk of developing NEC was significantly more if infants had any of these risk factor (p < 0.001). Incidence of severe birth asphyxia was more in Stage I cases (35.7% vs 10.3%, p < 0.05). The age at presentation was 4.9 +/- 4.8 days and majority (96%) presented during the first 14 days. The overall survival was 61% and was 70.5, 77.8 and 13.3% in Stages I, II and III, respectively. VLBW and preterm infants had a higher mortality.

Age Factors↗
PubMed1993

Neonatal necrotizing enterocolitis: a clinical study.

Necrotizing enterocolitis was found in 77 infants over a 5 year period. Diagnosis of NEC was established on 4.9 + 4.8 days in babies with birth weight of 1667 + 577 grams and the gestational age of 33.3 + 2.6 weeks. Definite disease occurred in 33 (42.9%) babies while there was strong suspicion in another 44 (57.1%) babies. Prefeed gastric residue (98.7%), abdominal distension (97.3%), lethargy (78.7%), hypotonia (60%) and jaundice (48%) were the main presenting features. However, blood in stools and abdominal wall erythema were found in 38.7% babies. About one third of infants had a positive blood culture. Pneumatosis intestinalis was present in 83.9% of babies and pneumoperitoneum was seen in 35.5% of neonates with NEC. Ileo-ceco-colic region was the commonest site of involvement. Overall survival was 61% and survival with Stage III was only 13%. Birth weight less than 1500 g, gestational age less than 32 weeks, erythema of the abdominal wall, intra-abdominal mass, portal venous gas in abdominal X-ray and Gram negative septicemia were associated with higher mortality.

Age of Onset↗
PubMed1993

Effect of failed computed tomography-guided and endoscopic drainage on pancreatic pseudocyst management.

BACKGROUND: Computed tomography and endoscopic drainage are used increasingly to treat pancreatic pseudocysts (PP). We reviewed our experience with PP to compare the outcomes of patients operated on initially (group 1) with those whose nonoperative treatment failed (computed tomography-guided or endoscopic drainage) before operation (group 2). METHODS: The records of 70 consecutive patients operated on for PP were reviewed. The 52 patients (74%) in group 1 and 18 (26%) in group 2 were compared in terms of clinical features, laboratory test results on examination and before operation, operative findings, morbidity, mortality, and recurrence rates. RESULTS: Before the initial drainage attempt, mean serum amylase level was higher in group 2 (542 +/- 25 vs 163 +/- 17 IU/L; p = 0.01). All other laboratory values were similar. Before operative drainage, group 2 patients had lower hemoglobin (10.7 +/- 0.5 vs 12.2 +/- 0.3 gm/dl; p < 0.05) and serum albumin level (2.7 +/- 0.2 vs 3.5 +/- 0.1 mg/dl; p < 0.01) than group 1. Morbidity was twice as frequent in group 2 (33% vs 14%). The time from initial attempt at drainage to PP resolution was longer in group 2 (104 +/- 36 vs 20 +/- 4 days; p = 0.01). However, the time from operation to resolution was similar in both groups (21 +/- 8 vs 20 +/- 4 days). CONCLUSIONS: Failed nonoperative drainage is associated with a protracted illness and carries a risk of increased morbidity after operative intervention.

Adult↗
PubMed1993

Allograft rejection after penetrating keratoplasty for keratoconus.

We retrospectively studied 91 penetrating keratoplasties in 65 patients to evaluate the overall incidence of allograft rejection and the incidence in unilateral as compared with bilateral cases following penetrating keratoplasty for keratoconus. All surgeries were performed by the senior author following a standardized technique. The average age of the patients was 35 years; the average follow up, 6.5 years. Nine of the 91 grafts (9.9%) were rejected. The time of rejection varied from 6 months to 13 years after surgery. Eight of the nine rejections (88.9%) were reversible with steroid treatment and have survived up to 10 years. One graft failure requiring repeat penetrating keratoplasty (1.1%) occurred 13.25 years after surgery. The unrejected clear grafts have survived up to 21.5 years. The results of this study support the excellent prognosis of penetrating keratoplasty for keratoconus.

Adolescent↗
PubMed1993

Cognitive and neurologic deficits in the MRL/lpr mouse: a clinicopathologic study.

OBJECTIVES: Determine if the MRL/lpr mouse develops neurological deficits and, if so, the pathologic basis for these deficits. Antiphospholipid antibodies (aPL) are associated with ischemic stroke, multiinfarct dementia, chorea, and cardiac valvular abnormalities. The MRL/lpr mouse develops high titer anticardioplin antibodies (aCL) suggesting that it may be used as a model for the neurological complications of aPL. METHODS: We undertook a prospective clinicopathologic study comparing the MRL/lpr mouse against its congenic strain, the MRL/+ mouse. We studied 15 MRL/pr and 15 MRL/lpr and 15 MRL/+ mice at 16 to 20 weeks and a group of 16 mice of each strain at 8 to 10 weeks. aCL and anti-DNA antibodies were measured by ELISA: Cognitive and neurological deficits were assessed by a water maze and a standardized rodent neurological examination. The brains and cardiac valves of the mice were then examined pathologically. RESULTS: The MRL/lpr mice had significantly elevated aCL at both ages. Cognitive and sensorimotor deficits were apparent at 16 weeks but no correlation could be found with aCL or anti-DNA titer. Even at 8 weeks the MRL/lpr mice performed poorer on the water maze when compared to their age matched congenic strain. No evidence of cerebral infarction was found but mononuclear infiltrates were found in the choroid plexus of all the MRL/lpr mice at both 10 and 20 weeks. No evidence of cardiac valve pathology was seen at 20 weeks. CONCLUSIONS: (1) The MRL/lpr mouse develops cognitive and neurologic deficits. The etiology of these deficits is not clear but may be related to early infiltration of the central nervous system with mononuclear cells. (2) Despite the elevated aCL, evidence of cerebral infarction or mitral valve abnormalities could not be found.

Animals↗
PubMed1992

Carcinoma of the rectal pouch following restorative proctocolectomy. Report of a case.

A case of adenocarcinoma developing in the pouch following restorative proctocolectomy is presented. This seems to be the third reported in the literature. The carcinoma developed from the remnants of precancerous rectal mucosa left in the muscular rectal cuff. The patient had been suffering from ulcerative colitis for 17 years prior to the development of the malignancy. He presented with features of subacute intestinal obstruction. Diagnosis was by sigmoidoscopic examination of the pouch and biopsy. He was treated with abdominoperineal resection of the pouch and rectum, followed by chemotherapy.

Adenocarcinoma↗
PubMed1992

Mutagenesis of the yeast plasma membrane H(+)-ATPase. A novel expression system.

The plasma membrane H(+)-ATPase of the yeast Saccharomyces cerevisiae is a prototype for the mutagenic analysis of structure-function relationships in P-type cation pumps. Because a functional H+ pump is required for viability, wild-type ATPase must be maintained in the plasma membrane for normal cell growth. Our expression strategy involves a rapid switch in expression from the wild-type ATPase gene to a mutant allele followed by entrapment of the newly synthesized mutant enzyme in an internal, secretory vesicle pool. The isolated vesicles prove to be ideally suited for the study of the catalytic and transport properties of the ATPase. Work to date has focused on conserved residues in the vicinity of the aspartyl-phosphate reaction intermediate. Substitution of Asp378 with Glu, Ser, or Asn and of Lys379 with Gln prevents normal biogenesis of the mutant ATPase. The more conservative Lys379----Arg mutation was tolerated, but with a sixfold loss of activity and substantial alterations in Km for ATP and Ki for vanadate. Nonconservative replacement of Thr380, Thr382, or Thr384 with Ala led to inactive enzyme, whereas the conservative change to Ser caused a two to threefold reduction in ATP hydrolysis and H(+)-pumping. Taken together, the results are consistent with an essential role for these invariant residues in phosphate-binding and ATP hydrolysis.

Amino Acid Sequence↗
PubMed1992

Use of grafts smaller than the opening for keratoconic myopia and astigmatism. A prospective study.

A prospective study was conducted on 15 consecutive keratoconic eyes to evaluate the use of grafts smaller than the opening in keratoconic myopia and astigmatism. All surgeries were performed by the senior author. Average age of the patients was 41.1 years. Average follow-up was 1.6 years. After all sutures were removed, results showed an average decrease in myopia of 13.24 diopters (D) (range 1.75 to 23.25) principally from corneal flattening and a small reduction in axial length. Average postoperative spherical equivalent was -2.17 D (range +1.50 to -7.25). The average postoperative astigmatism was 3.78 D (range 1.75 to 6.00). This study and a previous retrospective study suggest that the use of grafts 0.25 mm smaller than the opening, i.e., 7.50/7.75 mm, for penetrating keratoplasty in keratoconus is justified.

Adult↗
PubMed1991

Expression of the yeast plasma membrane [H+]ATPase in secretory vesicles. A new strategy for directed mutagenesis.

Secretory vesicles that accumulate in the temperature-sensitive sec6-4 strain of yeast have been shown to contain a vanadate-sensitive ATPase, presumably en route to the plasma membrane (Walworth, N. C., and Novick, P. J. (1987) J. Cell Biol. 105, 163-174). We have now established this enzyme to be a fully functional form of the PMA1 [H+]ATPase, identical in its catalytic properties to that found in the plasma membrane. In addition, the secretory vesicles are sealed tightly enough to permit the measurement of ATP-dependent proton pumping with fluorescent probes. We have gone on to exploit the vesicles as an expression system for site-directed mutants of the ATPase. For this purpose, a sec6-4 strain has been constructed in which the chromosomal PMA1 gene is under control of the GAL1 promoter; the mutant pma1 allele to be studied is introduced on a centromeric plasmid under the control of a novel heat shock promoter. In galactose medium at 23 degrees C, the wild-type ATPase is produced and supports normal vegetative growth. When the cells are switched to glucose medium at 37 degrees C, however, the wild-type gene turns off, the mutant gene turns on, and secretory vesicles accumulate. The vesicles contain a substantial amount of newly synthesized, plasmid-encoded ATPase (5-10% of total vesicle protein), but only traces of residual wild-type PMA1 ATPase and no detectable mitochondrial ATPase, vacuolar ATPase, or acid or alkaline phosphatase. To test the expression strategy, we have made use of pma1-105 (Ser368----Phe), a vanadate-resistant mutant previously characterized by standard methods (Perlin, D. S., Harris, S. L., Seto-Young, D., and Haber, J. E. (1989) J. Biol. Chem. 264, 21857-21864). In secretory vesicles, as expected, the plasmid-borne pma1-105 allele gives rise to a mutant enzyme with a reduced rate of ATP hydrolysis and a 100-fold increase in Ki for vanadate. Proton pumping is similarly resistant to vanadate. Thus, the vesicles appear well suited for the production and characterization of mutant forms of the PMA1 [H+]ATPase. They should also aid the study of other yeast membrane proteins that are essential for growth as well as heterologous proteins whose appearance in the plasma membrane may be toxic to the cell.

Catalysis↗
PubMed1991

Study of the influence of left bundle branch block on the signal-averaged electrocardiogram: a qualitative and quantitative analysis.

UNLABELLED: To study the influence of left bundle branch block (LBBB) on the signal-averaged electrocardiogram (SAECG), quantitative and qualitative analyses of SAECG parameters were undertaken in 48 patients with electrocardiographic evidence of intrinsic LBBB and in 39 patients with a "normal" surface QRS duration (less than 120 msec) who underwent right ventricular pacing-induced LBBB. We assumed pacing of the right ventricular apex to be a suitable model of this conduction defect. Sustained monomorphic ventricular tachycardia (SMVT) was inducible in 16 of 48 patients with intrinsic LBBB and in 23 of 39 patients with pacing-induced LBBB. Utilizing a filter setting of 25 to 250 Hz, late potentials were defined as a total filtered QRS duration greater than or equal to 120 msec, a root mean square voltage in the terminal 40 msec (RMS 40) of less than or equal to 25 microV, and the duration of signals less than 40 microV (LAS 40) of greater than or equal to 38 msec. Only RMS 40 and LAS 40 criteria were used in patients with LBBB. Prolongation of LAS 40 and fragmentation of signals in the terminal portion of the filtered QRS were characteristic of all patients with LBBB aberration. Of those patients with intrinsic LBBB, the mean total filtered QRS duration, RMS 40, and LAS 40 for inducible and noninducible patients were significantly different (170 +/- 28, 16 +/- 10, 55 +/- 24, and 153 +/- 18 msec, 25 +/- 10 microV, 33 +/- 16.9 msec; p = 0.04, 0.009, and 0.007, respectively). Noninducible patients with a normal QRS duration demonstrated a 60% decrement in the mean RMS 40 value during pacing-induced LBBB. These changes resulted in a 59% false positive incidence of late potentials during pacing-induced LBBB. This correlated with a similarly low mean RMS 40 value in patients with intrinsic LBBB and no inducible SMVT, hence giving rise to a false positive incidence of late potentials of 63%. Since "standard" RMS 40 and LAS 40 criteria resulted in low specificity and positive predictive value, new parameters were selected and analyzed. The combination of RMS 40 less than or equal to 17 microV plus LAS 40 greater than or equal to 55 msec yielded the best overall statistical result, with a sensitivity, specificity, and total predictive accuracy of 69%, 81%, and 77%, respectively. IN CONCLUSION: (1) A reduction of RMS 40, prolongation of LAS 40, and fragmentation of signals in the terminal portion of the filtered QRS are characteristics of LBBB.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗