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Biomedical subjects

I M Rao

Publications and source records attributed to I M Rao.

At least 19 recordsLinked to original sources
PubMed2003

A global assessment using PCR techniques of mycorrhizal fungal populations colonising Tithonia diversifolia.

Tithonia diversifolia (Mexican sunflower) is a shrub commonly used as a green manure crop in Central and South America, Asia and Africa as it accumulates high levels of phosphorus and other nutrients, even in depleted soils. In root samples collected from the global distribution of Tithonia, we examined the degree of mycorrhizal colonisation and estimated the families of associated arbuscular mycorrhizal (AM) fungi. No colonisation by ectomycorrhizas was found. The degree of colonisation by AM fungi was on average 40%, but ranged between 0 and 80%. No mycorrhizal colonisation was found in the samples collected from the Philippines or in one each of the Rwandan and Venezuelan samples. Throughout its global distribution (Costa Rica, Nicaragua, Indonesia, Honduras, Mexico, Kenya and Rwanda), Tithonia forms mainly associations with Glomaceae. Only in one location in Nicaragua were associations with another family ( Acaulosporaceae) found.

Asteraceae↗
PubMed2001

The high level of aluminum resistance in signalgrass is not associated with known mechanisms of external aluminum detoxification in root apices.

Al resistance of signalgrass (Brachiaria decumbens Stapf cv Basilisk), a widely sown tropical forage grass, is outstanding compared with the closely related ruzigrass (Brachiaria ruziziensis Germain and Evrard cv Common) and Al-resistant genotypes of graminaceous crops such as wheat, triticale, and maize. Secretion of organic acids and phosphate by root apices and alkalinization of the apical rhizosphere are commonly believed to be important mechanisms of Al resistance. However, root apices of signalgrass secreted only moderately larger quantities of organic acids than did those of ruzigrass, and efflux from signalgrass apices was three to 30 times smaller than from apices of Al-resistant genotypes of buckwheat, maize, and wheat (all much more sensitive to Al than signalgrass). In the presence, but not absence, of Al, root apices of signalgrass alkalinized the rhizosphere more than did those of ruzigrass. The latter was associated with a shortening of the alkalinizing zone in Al-intoxicated apices of ruzigrass, indicating that differences in alkalinizing power were a consequence, not a cause of, differential Al resistance. These data indicate that the main mechanism of Al resistance in signalgrass does not involve external detoxification of Al. Therefore, highly effective resistance mechanisms based on different physiological strategies appear to operate in this species.

Aluminum↗
PubMed2000

Roots of nutrient-deprived Brachiaria species accumulate 1,3-di-O-trans-feruloylquinic acid.

A novel di-hydroxycinnamoylquinic acid ester, 1,3-di-O-trans-feruloylquinic acid (DFQA), was isolated from roots of nutrient-deprived Brachiaria species--the most widely sown tropical forage grasses in South America. In contrast to other so far characterized quinic-acid esters, DFQA exists in a chair conformation with the carboxylic group in the axial orientation. It accumulates in older parts of the root system, but not in root apices or shoots. Higher levels were found in B. ruziziensis, which is poorly adapted to infertile acid soils, than in well adapted B. decumbens. DFQA was also found in the soil, most likely as a result of root decay, because it was not detected in root exudates of plants cultivated in solution culture. Nitrogen and phosphorus deficiency--but not aluminum toxicity or deprivation of other nutrients--stimulated its synthesis in roots. Its accumulation was correlated with a shift in biomass partitioning toward the root system.

Coumaric Acids↗
PubMed1995

Anterior pulmonary translocation for repair of truncus arteriosus with interrupted arch.

A newborn was found to have truncus arteriosus and an interrupted aortic arch, and underwent primary repair. The patient did well initially, but, by 8 weeks postoperatively, showed evidence of severe compression of the right pulmonary artery. At reoperation, the pulmonary artery was found to be compressed by a large aortic root (truncal root) and the retroaortic area was narrowed. The pulmonary artery bifurcation was therefore translocated anteriorly to alleviate the compression.

Aorta, Thoracic↗
PubMed1995

Strategies for repair of congenital heart defects in infants without the use of blood.

Eleven infants and children with a body weight of less than 10 kg (median weight, 6.8 kg) whose parents were Jehovah's Witnesses underwent repair (n = 10) or palliation (n = 1) of congenital heart defects without the use of blood products and with (n = 9) or without (n = 2) cardiopulmonary bypass (CPB). In 1 neonate (weight, 3.2 kg) with critical aortic stenosis, moderate hypothermia and a 3.5-minute period of inflow occlusion and circulatory arrest allowed an aortic valvotomy; in another patient (weight, 7.0 kg) with tricuspid and pulmonary atresia, transposition of the great arteries, and persistent left superior vena cava, a bilateral bidirectional cavopulmonary shunt procedure was performed without CPB. Use of heparin-bonded tubing allowed reduction of the initial dose of heparin sodium to 1 mg/kg. Tissue perfusion and oxygenation on bypass were adequate, as evidenced by a mean lowest pH of 7.38 +/- 0.09 and a mean lowest venous oxygen tension of 65.0 +/- 36.2 mm Hg. Although the mean postoperative hematocrit (Hct) was lower than the mean preoperative Hct (p < 0.05, analysis of variance and Scheffe's F test), the Hct within 2 hours after CPB was restored to a value (mean Hct, 27.5% +/- 1.0%) between the preoperative Hct (mean value, 42.7% +/- 3.5%) and the lowest Hct on CPB (mean value, 18.4% +/- 1.4%). The Hct at discharge was 31.8% +/- 1.1%. The median postoperative blood loss was 9 mL/kg. There was no perioperative mortality. The median stay in the intensive care unit and the hospital was 2 days and 6 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Loss, Surgical↗
PubMed1995

Univentricular repair. Early and midterm results.

A total of 202 patients (62 with tricuspid atresia and 140 without tricuspid atresia) underwent univentricular repair at our unit from January 1990 to September 1994. Of these patients, 182 had nonfenestrated and 20 had fenestrated interatrial baffles. Early mortality was 15.9% (29/182) in the group with nonfenestrated baffles and 5% (1/20) in the group with fenestrated baffles. The follow-up period ranged from 2 to 58 months. Seven late deaths occurred, and five patients were lost to follow-up. Of 160 patients who have been evaluated in the outpatient department in the past 3 months, 142 (88.75%) required no cardiac medicines and were in functional class I. Risk factors analyzed for early mortality and significant effusion were age, preoperative diagnosis, type of Fontan modification, cardiopulmonary bypass time, aortic crossclamp time, pulmonary artery size, associated pulmonary arterioplasty, takedown of systemic-pulmonary artery shunt, and pulmonary artery debanding, along with the Fontan operation. Bypass time exceeding 120 minutes was associated with a higher early mortality (12/47 vs 18/155; p = 0.0187). Bypass time exceeding 120 minutes (p = 0.0456) and aortic crossclamp time exceeding 60 minutes (p = 0.0278) were associated with significant postoperative effusion. Other factors were not associated with any significantly increased risk for early mortality or postoperative effusions. Fenestration of the interatrial baffle appeared to decrease early mortality, although the numbers are too small to be statistically significant. The prevalence of effusions did not differ significantly between the group with fenestrated baffles and the group without fenestrated baffles.

Cardiopulmonary Bypass↗
PubMed1993

Characterization of progesterone biosynthesis in a transformed granulosa cell line.

The study of regulation of steroidogenesis in primary cultures of rat granulosa cells is difficult because the cells do not undergo more than one cell doubling in culture. Furthermore, there is size and steroidogenic heterogeneity in granulosa cells and it is difficult to obtain pure, functionally defined populations. Hence, it is advantageous to develop a homogeneous population of granulosa cells. In this report we describe the characterization of one such cell line (Rao-gcl-29) developed from diethylstilbestrol treated immature rat granulosa cells by transformation with SV40 T antigen. In this cell line cyclic AMP analogs induce high levels of progesterone biosynthesis, though there was no effect on estradiol biosynthesis. Also, FSH and hCG have no effect on progesterone biosynthesis. In the presence of FBS medium (20% fetal bovine serum in DMEM/F-12) and enriched medium (10% fetal bovine serum, 10% horse serum and 2% UltraSer G in DMEM/F-12 medium), 1 mM cAMP analogs induce high levels of progesterone biosynthesis up to 96 h. Ultrastructural features of the cell line resemble those of primary granulosa cells, in addition to forming gap junctions. Cyclic AMP analogs also induced cytochrome P450scc mRNA in this cell line by 48 h, and this effect is apparent by 24 h. Thus, this cell line could be useful in understanding the molecular mechanisms of regulation of cytochrome P450scc gene regulation.

Animals↗
PubMed1991

Heterogeneity in granulosa cells of developing rat follicles.

The present study was designed to characterize the granulosa cell subpopulations derived from rats in which ovarian growth was induced by diethylstilbestrol (DES) or in which growth and differentiation was induced by pregnant mare's serum gonadotropin (PMSG). In the DES model, immature rats were given two separate injections of 2 mg DES/rat s.c. on 25 and 26 days of age and were killed 24 hr after the second injection. In the PMSG model, rats on day 28 were given 8 IU of PMSG s.c. and were killed 54 hr later. Granulosa cells were isolated from the ovaries, separated on a continuous Percoll density gradient, and divided into 12 fractions. The cells in each fraction were cultured in the presence of androstenedione with or without 20 ng/ml of follicle-stimulating hormone (FSH) and estradiol and progesterone in the incubation medium were measured. In DES-treated rats, granulosa cells in fractions 4 and 5 and fractions 9 and 10 contained about 30-40% of total cell yield and showed high steroidogenic potential. Granulosa cells from fractions 6, 7, and 8, which represent 55-60% of total cell yield, produced relatively low amounts of steroids on a per-million-cell basis. FSH was required for the stimulation of steroidogenesis. In granulosa cells from the PMSG treated rats, aromatase activity appeared maximally induced and incubation with FSH in vitro did not bring about any further increase. However, in vitro incubation with FSH was required for progesterone production. Furthermore, the granulosa cells from the PMSG treated rats also showed much more active estradiol and progesterone synthesis in fractions 9-12 as compared with lower density fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Flow cytometric analysis of granulosa cells from developing rat follicles.

Immature rats were treated with diethylstilboestrol (DES) or pregnant mares' serum gonadotropin (PMSG) and forward angle light-scatter (FALS) and 90 degrees light-scatter (90 degrees LS) signals were used to measure the size and the granularity (internal organization) of the granulosa cells, respectively. The results confirmed the presence of two major populations of granulosa cells in the ovaries of both groups of rats, with the same percentage of larger cells in both treatments (52.3% in DES, 49.5% in PMSG). Since DES treatment brings about granulosa cell growth while PMSG treatment causes growth and differentiation, it is evident that there is heterogeneity in granulosa cell sizes during different states of growth and differentiation. There was also heterogeneity in sizes of granulosa cells harvested from follicles of small (less than 210 microns), medium (210-420 microns) and large (greater than 420 microns) diameter. Quadrant analysis of granulosa cells in various fractions collected from Percoll gradients suggested an increase in granularity in the small and large granulosa cell populations. Cell cycle analysis of small and large granulosa cell populations collected from large follicles of rats treated with PMSG indicated that each population was distributed in G0/G1, S and G2/M phases. These results demonstrate that populations of small and large granulosa cells exist in rat ovarian follicles during various stages of growth and differentiation.

Animals↗
PubMed1991

Surgical treatment of total anomalous pulmonary venous connection.

Fourteen infants ranging in age from 18 days to 10 months (median age = 4 months) underwent surgical repair of total anomalous pulmonary venous connection (TAPVC) between September, 1988 and December, 1989. The anomalous drainage was supracardiac in nine, cardiac in two, infracardiac in one and mixed in one. One patient had a complex type of TAPVC. There were two hospital deaths, one a critically ill three week old infant with obstructed infracardiac TAPVC and the other with complex TAPVC. There was no late death. All twelve survivors are in NYHA functional Class 1. Postoperative echocardiography revealed unobstructed pulmonary blood flow in all of them. Surgical correction of TAPVC in infancy has been performed with gratifying results. A high index of suspicion, early diagnosis, prompt referral and an aggressive surgical approach are essential for success in this otherwise lethal condition.

Cardiac Surgical Procedures↗
PubMed1990

Surgical treatment of major intracardiac lesions associated with discordant atrioventricular connexion.

Thirteen patients with a discordant atrioventricular connexion underwent repair of major associated intracardiac defects. Of the patients, 10 had a discordant ventriculoarterial connexion while 3 had double outlet from the morphologically right ventricle. A ventricular septal defect was the most frequently encountered lesion, present alone or in combination with other lesions in all patients. The other major lesions were pulmonary stenosis in 8, Ebstein's malformation of the left atrioventricular valve in 2, and calcific aortic valve disease in one. The operations performed were closure of the ventricular septal defect in 4 patients, closure of the ventricular septal defect with pulmonary valvotomy in 3 patients (one of whom subsequently underwent replacement of the left atrioventricular valve). Modified Fontan's procedure was performed in 6 patients, one of whom also had replacement of the aortic valve. There was no operative death, although there was one early death on the 40th postoperative day due to septicemia. There has been no late death after an average follow-up of 1.2 years. There was one case of surgically induced complete heart block. All other patients are in normal sinus rhythm in New York Heart Association functional class I or II. Elective repair of major intracardiac anomalies in association with a discordant atrioventricular connexion can now be accomplished safely. The modified Fontan's procedure is a viable alternative in certain cases to the placement of an external valved conduit for relief of pulmonary outflow tract obstruction.

Adolescent↗
PubMed1990

Cardiac injuries--a clinical and autopsy profile.

One hundred two patients sustaining cardiac injuries over a 4-year period were analysed to highlight the natural history of the cardiac injuries. There were 45 blunt, 36 stab, and 21 gunshot injuries. The injury involved the ventricle in 85, atrium in seven, pulmonary artery in five cases, and resulted in crush injury to the heart in the remaining five cases. Thirty-three patients (32.3%) died on the scene and 58 (56.9%) died during the transportation. Only 11 patients (10.8%) reached the hospital alive, and ten of these patients survived following thoracotomy and repair of the cardiac injury. The factors influencing the natural course of cardiac injury were analysed: 2.2% of patients with blunt cardiac trauma reached the hospital alive compared to 19.4% with stab and 14.3% with gunshot injuries; ventricular injuries had a greater prehospital mortality compared to atrial or pulmonary artery injuries; 11.3% of patients sustaining injury to right ventricle reached the hospital alive compared to 3% of those with left ventricular injuries. These data emphasize the need for rapid transport, immediate recognition, and aggressive surgical management, to make a favourable impact on the natural history of cardiac injuries.

Adolescent↗
PubMed1990

Leaf Phosphate Status, Photosynthesis, and Carbon Partitioning in Sugar Beet: III. Diurnal Changes in Carbon Partitioning and Carbon Export.

The effect of low phosphate supply (low P) was determined on the diurnal changes in the rate of carbon export, and on the contents of starch, sucrose, glucose, and fructose 2,6-bisphosphate (F2,6BP) in leaves. Low-P effects on the activities of a number of enzymes involved in starch and sucrose metabolism were also measured. Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers and the low-P treatment induced nutritionally. Low-P treatment decreased carbon export from the leaf much more than it decreased photosynthesis. At growth chamber photon flux density, low P decreased carbon export by 34% in light; in darkness, export rates fell but more so in the control so that the average rate in darkness was higher in low-P leaves. Low P increased starch, sucrose, and glucose contents per leaf area, and decreased F2, 6BP. The total extractable activities of enzymes involved in starch and sucrose synthesis were increased markedly by low P, e.g. adenosine 5-diphosphoglucose pyrophosphorylase, cytoplasmic fructose-1,6-bisphosphatase, uridine 5-diphosphoglucose pyrophosphorylase, and sucrose-phosphate synthase. The activities of some enzymes involved in starch and sucrose breakdown were also increased by low P. We propose that plants adapt to low-P environments by increasing the total activities of several phosphatases and by increasing the concentrations of phosphate-free carbon compounds at the expense of sugar phosphates, thereby conserving Pi. The partitioning of carbon among the various carbon pools in low-P adapted leaves appears to be determined in part by the relative capacities of the enzymes for starch and sucrose metabolism.

Journal Article↗