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Biomedical subjects

R Kumar

Publications and source records attributed to R Kumar.

At least 1,099 records · Page 61Linked to original sources
PubMed1989

Wilms' tumour (nephroblastoma) in Zimbabwe.

Over a 3-year period (1984-1987), 57 cases of Wilms' tumour (nephroblastoma) were diagnosed and managed at the Parirenyatwa Hospital in Harare. Two-thirds of the patients were younger than 4 years of age. The majority of patients presented with advanced disease, most likely the result of delayed and late presentation. In spite of this, and with a multimodal approach to management, results obtained were fairly good and compare favourably with results obtained elsewhere in developed countries. Forty-four of the 57 patients are presently alive and disease free 10 to greater than 36 months after presentation. Overall, 2-year relapse-free survival was 64.9%.

Child↗
PubMed1989

A method for the rapid screening of human blood samples for the presence of HIV-1 sequences: the probe-shift assay.

In theory, screening directly for the human immunodeficiency virus (HIV) DNA has advantages over screening for HIV-related antibodies; however, the HIV genome appears to be present only in a small fraction of peripheral blood cells from infected individuals. The polymerase chain reaction (PCR) specifically amplifies defined DNA segments, permitting the identification of specific DNA segments even if they are present in a fraction of cells. HIV-derived PCR-amplified segments have been detected by Southern transfer, "dot-blot" hybridization, and digestion with restriction endonucleases. Unfortunately, PCR may amplify not only the single segment of interest but also irrelevant segments, which can be incorrectly identified as HIV related. We describe here an alternative approach to specific detection of PCR-amplified DNA segments, the probe-shift assay, that is simpler, faster, and less subject to erroneous identification than the previously described techniques. The probe-shift assay relies on the hybridization of an appropriately labeled oligonucleotide probe to the amplified segment in solution. The hemiduplex formed between the amplified DNA and the probe is detected following fractionation on nondenaturing gels. This procedure is sufficiently sensitive to detect a single infected cell in the presence of more than 10(5) uninfected cells and has been applied directly to clinical samples.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Enteroaggregative Escherichia coli associated with persistent diarrhea in a cohort of rural children in India.

A cohort of 452 rural children was followed longitudinally for 13 mo to ascertain the role of HEp-2 cell adherent Escherichia coli and other pathogens in causing acute (less than or equal to 14 d) and persistent (greater than 14 d) diarrhea. Aeromonas, Campylobacter jejuni, E. coli manifesting localized adherence to HEp-2 cells and enterotoxigenic E. coli were significantly associated with acute diarrhea. E. coli strains that exhibit aggregative adherence, so-called enteroaggregative E. coli, a newly-described category of diarrheagenic E. coli distinct from enterotoxigenic, enteroinvasive, enterohemorrhagic, and enteropathogenic E. coli, were found significantly more often in patients with persistent diarrhea (29.5%) than with acute diarrhea (12.8%) (P = .0052) or controls (9.9%) (P = .0006).

Acute Disease↗
PubMed1989

Coexisting hereditary methaemoglobinaemia and heterozygous beta-thalassaemia.

Cyanosis was noted within a few weeks after birth in two sisters. On investigation the cause of cyanosis was found to be congenital methaemoglobinaemia due to NADH diaphorase deficiency. Heterozygous beta-thalassaemia was present as an additional incidental finding in one of the sisters, but did not contribute to the symptoms, thus showing that the two diseases, when coexistent, do not pose additional haematological problems. However, it is possible that the beta-thalassaemia counteracts the tendency to compensatory erythrocytosis induced by methaemoglobinaemia.

Child, Preschool↗
PubMed1989

Increased faecal alpha-1-antitrypsin excretion in children with persistent diarrhoea associated with enteric pathogens.

The random faecal alpha-1-antitrypsin (AT) excretion (mg/g dry weight of stool) was measured in 30 infants and children (mean age 10.8 +/- 8 mo.) with protracted diarrhoea (duration greater than or equal to 21 days) and failure to thrive and 27 normally nourished children (mean age 13 +/- 4.5 mo.) without any gastrointestinal symptoms in the preceding 12 weeks. The associated factors in patients with protracted diarrhoea and their mean faecal AT during active disease and 3-4 weeks after recovery were as follows: Enteropathogenic E. coli 5 (7.9 +/- 5.5; 3.2 +/- 0.6), Giardia lamblia 4 (3.9 +/- 1.8; 2.5 +/- 0.7), Salmonella typhimurium 3 (4.0 +/- 0.2; 3.8 +/- 0), secondary carbohydrate intolerance 11 (2.5 +/- 0.9; 2.4 +/- 0.8), and others 7 (3.4 +/- 0.7; 3.0 +/- 0.5), respectively. Of all the patients with protracted diarrhoea the mean AT in the E. coli, Giardia and Salmonella groups were significantly higher than the mean in the control group (2.1 +/- 0.8) and following treatment and recovery the values were comparable to that in the controls. All the 6 patients with very high faecal AT (greater than mean + 3 SD of controls) were associated with an enteric pathogen.

Diarrhea, Infantile↗
PubMed1989

Transfection of a human gene that corrects the Lec1 glycosylation defect: evidence for transfer of the structural gene for N-acetylglucosaminyltransferase I.

Chinese hamster ovary (CHO) glycosylation mutants provide an approach to cloning mammalian glycosyltransferases by transfection and gene rescue. In this paper, complementation of the lec1 CHO mutation by human DNA is described. Lec1 transfectants expressed human N-acetylglucosaminyltransferase I (GlcNAc-TI) activity and possessed common human DNA fragments. Cloning of GlcNAc-TI should therefore be possible.

Animals↗
PubMed1989

The clavicle: normal and abnormal.

The clavicle is an unusual long bone with many unique embryologic features. It is often involved in congenital and acquired disorders. Traumatic, inflammatory, neoplastic, metabolic and many other miscellaneous lesions may also affect the bone. Because of its ligamentous attachments and the presence of articulations at both ends, the clavicle can also be involved in arthritic diseases. This article illustrates the radiographic manifestations of many of the disorders of the clavicle that are commonly encountered in clinical practice.

Bone Diseases↗
PubMed1989

The many faces of neuroblastoma.

Neuroblastoma is a common tumor in childhood. It arises in the adrenal gland or in various extraadrenal primary sites of the sympathetic chain. Clinically, it may present as an abdominal mass or as disseminated metastatic disease. We studied 52 patients with neuroblastoma, and the typical and unusual radiographic features of the disease are presented.

Adrenal Gland Neoplasms↗
PubMed1989

Calcium pump epitopes in placental trophoblast basal plasma membranes.

The syncytiotrophoblast represents the primary cellular barrier between maternal and fetal circulations in the placenta. Large amounts of Ca2+ are transported across this barrier by mechanisms that are not clearly understood. To further understand this phenomenon, we examined rat and human placenta by immunohistochemical and protein blotting techniques with a monoclonal antibody raised against the human erythrocyte plasma membrane Ca2+ pump. Immunohistochemistry with this antibody showed specific staining in the human placenta of the basal (fetal facing) surface of the syncytiotrophoblast. In the rat placenta, immunohistochemistry also showed specific staining of the innermost (fetal facing) layer of the trophoblast and the basal surface of the endoderm of the intraplacental yolk sac. In Western blots of placental homogenates and membranes, the monoclonal antibody bound to a 140,000-mol wt band, characteristic of Ca2+ pumps in other tissues. Western blots of isolated basal membranes showed more intense staining than isolated microvillous membranes, confirming the results of the immunohistochemistry. In addition, Ca2+ transport in basal membrane vesicles from human placenta was inhibited by polyclonal antibodies prepared against the erythrocyte Ca2+ pump. We conclude that basal (fetal facing) layers of human and rat placentas contain a high-affinity Ca2+ pump situated to transport Ca2+ from the maternal to the fetal circulation.

Animals↗
PubMed1989

Plasma membrane calcium pump and 28-kDa calcium binding protein in cells of rat kidney distal tubules.

In an effort to extend our studies on Ca2+ pumps to animal models, we developed a new monoclonal antibody (5F10) prepared against the human erythrocyte Ca2+-Mg2+-adenosinetriphosphatase (ATPase) that recognizes a protein of approximately 140 kDa in rat kidney homogenates. Enzyme-linked immunosorbent assays show that monoclonal antibody 5F10 binds purified Ca2+-Mg2+-ATPase and rat kidney membrane extracts in a concentration-dependent manner. In paraffin-embedded tissue sections, antibody 5F10 binds to an epitope in the basolateral membranes of rat kidney distal convoluted tubule principal cells. The antibody does not bind to intercalated cells. The latter cells were characterized by the presence of large amounts of carbonic anhydrase C. Polyclonal antibodies directed against chick intestinal 28-kDa vitamin D-dependent calcium binding protein (28-kDa CaBP) also bind epitopes in distal convoluted tubule cells, connecting tubules, and portions of collecting duct but not intercalated cells. Western blot and 45Ca blot analysis of renal cytosolic proteins showed that the polyclonal 28-kDa CaBP-directed antibody detects a protein which also binds calcium. Western blot analysis with monoclonal antibody 5F10 shows binding to both the authentic purified erythrocyte Ca2+ pump (approximately 138 kDa) and to tryptic fragments of this pump. Antibody JA3, previously used for staining of human kidney tubules, reacts with a different set of tryptic fragments, showing that the two antibodies are directed against different regions or conformational determinants on the pump molecule. We show that Ca2+-Mg2+-ATPase and 28-kDa CaBP are present in the principal cells of the distal convoluted tubule of the rat and are absent in intercalated cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Role of lung injury in the pathogenesis of hyaline membrane disease in premature baboons.

To test the hypothesis that hyaline membrane disease (HMD) has a multifactorial etiology in which barotrauma plays a major role, we compared the immediate institution of high-frequency oscillatory ventilation (HFOV; 15 Hz, n = 5) with positive-pressure ventilation with positive end-expiratory pressure (PPV; n = 7) in premature baboons (140-days gestation) with HMD. Measurements of ventilation settings and physiological parameters were obtained and arterial-to-alveolar O2 (PaO2-to-PAO2) ratio and oxygenation index [(PaO2/PAO2)-to-mean airway pressure ratio (IO2)] were calculated. At death (24 h), static pressure-volume (PV) curves were performed, and phospholipids (PL) and platelet-activating factor (PAF) were measured in lung lavage fluid. Morphological inflation patterns were analyzed using a panel of standards. By design, mean airway pressure was initially higher (19 vs. 13 cmH2O) in the HFOV animals. PaO2-to-PAO2 ratio and IO2 progressively deteriorated in the PPV animals and then stabilized at significantly lower levels than with HFOV. PV curves from HFOV animals had significant increases in lung volume at maximum distending pressure, deflation volume at 10 cmH2O, and hysteresis area compared with PPV, which showed no hysteresis. Seven of seven PPV and only one of five HFOV animals had morphological findings of HMD. PL amount and composition in both groups were consistent with immaturity, even though the quantity was significantly greater in the PPV group. PAF was present (greater than or equal to 0.10 pmol) in six of seven PPV and in the only HFOV animal with HMD. We conclude that HFOV protected PL-deficient premature baboons from changes in gas exchange, lung mechanics, and morphology typical of HMD in this model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The psychiatrist in the obstetric unit. Establishing a liaison service.

The establishment and first 18 months of a psychiatric liaison service to a general hospital obstetric unit are described. The service was initially intended to predict antenatally those at risk of post-natal depression and to offer follow-up throughout pregnancy and in the post-natal period. However, a large proportion of referrals were of women currently unwell. Furthermore, post-natal follow-up in the community proved difficult. Referrals, diagnoses and disposal are analysed, leading to conclusions about the effectiveness and problem of such a service. The components of a comprehensive obstetric liaison provision are proposed, emphasising the need for strong community links built around a CPN service, allowing adequate postnatal psychiatric care.

Adult↗
PubMed1989

Maternal depression and the emotional development of the child.

Ninety-two women and their first-born children took part in a longitudinal survey of maternal mental health. When the children were four years old, their mothers were interviewed by means of the Behavioural Screening Questionnaire, and the children's problems were rated by a psychiatrist, who was unaware of the mothers' psychiatric histories or of assessments of their current health. As expected, mothers who were concurrently depressed reported significantly more behavioural difficulties in their children. Marital disharmony during pregnancy and a history of paternal psychiatric problems were also associated with later childhood behavioural difficulties. Children who scored below average on the McCarthy scales of cognitive abilities were also reported by their mothers to have more behavioural problems, but the children's behavioural difficulties at four showed no clear links with post-natal depression.

Adult↗
PubMed1989

The molecular cloning of the complementary deoxyribonucleic acid for bovine vitamin D-dependent calcium-binding protein: structure of the full-length protein and evidence for homologies with other calcium-binding proteins of the troponin-C superfamily of proteins.

We have cloned the cDNA for bovine intestinal vitamin D-dependent calcium-binding protein and, based on the sequence of the DNA, have deduced the structure of the full-length protein. The sequence of the cDNA clone predicts a protein comprised of 78 amino acids with a mol wt of 8788. The mRNA for the protein in bovine duodenum is about 500-600 bases in length. The protein sequence of bovine intestinal calcium-binding protein is 87% homologous with the sequence of porcine intestinal vitamin D-dependent calcium-binding protein and 81% homologous with the sequence of rat intestinal vitamin D-dependent calcium-binding protein. Hydrophilicity plots of the proteins noted above show that despite differences in amino acid sequence the proteins have similar patterns. In addition, the predicted secondary structure of the proteins is similar. Bovine intestinal calcium-binding protein shows 48.6% homology with the alpha-chain and 38.2% homology with the beta-chain of bovine S-100 protein and a similar high degree of homology with the beta-chain of human S-100 protein. The protein also demonstrates 36-43% homology with parvalbumin alpha and beta from various species and with troponin-C. There is some homology with the 28K vitamin D-dependent calcium-binding proteins. Vitamin D-dependent bovine intestinal calcium-binding protein is closely related to other mammalian intestinal calcium-binding proteins and to the S-100 proteins, parvalbumins, and troponin-C.

Amino Acid Sequence↗
PubMed1989

Serum anti-gliadin antibody profile in childhood protracted diarrhoea due to coeliac disease and other causes in a developing country.

Serum anti-gliadin antibody (AGA) titres were estimated by diffusion in a gel enzyme-linked immunosorbent assay in children with coeliac disease (n = 11), protracted diarrhoea of non-coeliac causes (n = 110), acute gastroenteritis (n = 20), protein energy malnutrition (n = 20), and asymptomatic, well-nourished children (n = 66). The mean IgG and IgA AGA titres were significantly higher (p less than 0.001) in children with coeliac disease than in any other groups. There was no significant difference (p greater than 0.01) in AGA titres in relation to age, nutritional status, or severity of villous injury. In patients with coeliac disease AGA titres showed a good correlation with disease activity. The specificity and sensitivity of the assay are discussed.

Antibodies, Anti-Idiotypic↗