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Biomedical subjects

M Singh

Publications and source records attributed to M Singh.

At least 793 records · Page 44Linked to original sources
PubMed1990

Analysis of macro- and microstructures of normal and pathological tissues by ultrasonic backscattering techniques.

A technique to obtain the spacing distribution of macro- and microstructures of hypercholestrolemic liver, lymphoidlucosed liver, rhinosporidium of man and ethmoidal tumour of bovine is presented. The method uses signal processing of spatially averaged spectra of ultrasonic backscattering from tissues in the frequency range 2-8 MHz. The macrostructure is obtained from signal processing of spectral modulation amplitude and the microstructure from the frequency dependence of backscattering coefficient. The results obtained show good correlation with tissue histologies.

Animals↗
PubMed1990

Adult Wilms' tumor: report of a case and review of the literature.

A 48 year old male presented with a one and a half year history of a progressively increasing, asymptomatic lump in the left hypochondrium and no history of hematuria. His general physical examination was unremarkable, and an abdominal examination revealed a large, firm, irregular and tender mass in the left hypochondrium extending into the lumbar region. Chest X-ray was normal. An intravenous urogram revealed a normally functioning right kidney with non-visualization of the left kidney. CT-scan of the abdomen revealed a large, mixed attenuating mass replacing the left kidney. At laparotomy, a large, fleshy, well-encapsulated tumor was found in the left kidney with no surrounding infiltration and a left radical nephrectomy was performed. Microscopic examination revealed a poorly differentiated tumor comprised of small round cells with focal areas of abortive embryonal tubular and glomerular differentiation suggestive of Wilms' tumor. The patient was advised chemotherapy and radiotherapy but he absconded and was lost to follow-up.

Humans↗
PubMed1990

Pilonidal disease of the umbilicus--a report of two cases.

Two cases of umbilical pilonidal sinus are reported herein. Both patients were young adult males aged 21 and 27 years, respectively. The predisposing factors are briefly discussed, however, the exact etiology of this disease remains unknown. Umbilectomy is the most commonly offered treatment and although it is rare, this entity probably goes undiagnosed in the majority of cases.

Adult↗
PubMed1990

Primary causes of neonatal deaths in a tertiary care hospital in Delhi: an autopsy study of 331 cases.

Of a total of 755 neonates who died between 1972 and 1988, 331 (43.9%) were subjected to necropsy examination. The ranking of major primary causes of neonatal death was as follows: infections 27.2%, hyaline membrane disease 20.2%, congenital malformations 19.6%, perinatal anoxia 14.5%, immaturity 5.1% and birth trauma 2.7%. Over the years, the prevalence of infections as the cause of death has consistently declined. Compared with that in other contemporary Indian studies, the prevalence of hyaline membrane disease is higher and that of infections and perinatal anoxia relatively lower.

Asphyxia Neonatorum↗
PubMed1990

Effect of prolonged ethanol intake on pancreatic lipids in the rat pancreas.

Although fat accumulation in acinar cells is the earliest histopathological change in the pancreas of patients and experimental animals, there are few long-term studies regarding lipid composition of the pancreas in alcoholism. In the present study, female Sprague-Dawley rats were divided into three groups each fed Wayne Rodent-Blox ad libitum or Lieber-DeCarli diet with 36% of maltose dextrin calories replaced with ethanol ad libitum, or isocaloric amounts of liquid diet for a period of 21 months resulting in changes of chronic pancreatitis in ethanol-fed rats. A low level of triglycerides, a high level of cholesterol ester and moderately elevated phospholipids, low incorporation of [14C]palmitoyl in triglycerides, increased 14C activity in phospholipids, and cholesterol ester were found by thin-layer chromatography in ethanol-fed rats. These data indicate that the pancreas synthesized triglycerides and other lipid components in the same way as liver and fat cells. Chronic ethanol ingestion caused marked changes in pancreatic lipid metabolism due to altered enzyme activities involved in the lipid pathways.

Alcoholism↗
PubMed1990

Passive protection studies in mice with monoclonal antibodies directed against the non-structural protein NS3 of dengue 1 virus.

Antibody-mediated enhancement of dengue virus replication is thought to be a mechanism contributing to the pathogenesis of dengue haemorrhagic fever and dengue shock syndrome. Enhancement is associated with antibodies to structural components of the virus. To circumvent the problem of immune enhancement, studies to identify protective antigens of dengue virus have involved non-structural proteins. Passive and active protection against lethal dengue virus infection in mice have been demonstrated with the non-structural protein NS1. In this study, the dengue virus non-structural protein NS3 was examined in passive protection studies with monoclonal antibodies prepared against NS3 of dengue 1 virus (Hawaiian). Five monoclonal antibodies that were authenticated to be reactive to NS3 were used to immunize 13- to 14-day old mice intraperitoneally. Thereafter, the mice were challenged intracerebrally with 100 LD50 of neurotropic dengue 1 virus and the survival indices of the mice were calculated. Significant decreases in survival indices (P less than 0.05), indicating increases in survival times were observed with four of five monoclonal antibodies tested. Monoclonal antibodies to NS3 of dengue 1 virus are able to increase the survival time of mice challenged with a lethal dose of dengue 1 virus, although the mechanism remains to be defined.

Animals↗
PubMed1990

Prevalence of human papillomavirus types 16 and 18 in cervical carcinomas: a study by dot and Southern blot hybridization and the polymerase chain reaction.

Histologically classified biopsies from 83 women with invasive cervical carcinoma were analyzed by dot blot hybridization for human papillomavirus (HPV) types 16 and 18 infection. Sixty of the 83 (72.3%) were found to contain HPV DNA, of which 43 (51.8%) contained HPV 16 DNA, 12 (14.5%) contained HPV 18 DNA and 5 (6.0%) contained both HPV 16 and 18 DNAs. Southern blot analysis on 65 specimens gave similar results. Of 23 specimens negative by dot blot, 21 were tested by the polymerase chain reaction. Seventeen of the 21 were positive for HPV DNA, of which 13 contained HPV 16 DNA and 4 contained both HPV 16 and 18 DNAs. In all, 95.1% (77/81) were positive for HPV 16 and/or 18 DNA sequences.

Adenocarcinoma↗
PubMed1990

Reye and Reye-like syndromes: results of a pilot study in Peninsular Malaya, 1986.

A pilot epidemiologic study of all cases of Reye and Reye-like syndromes was undertaken at 8 representative major hospitals in Peninsular Malaya from January 1st to December 31st 1986. The cases were classified as definitive Reye's syndrome, clinical Reye's syndrome and encephalo-hepatopathies. Less than 50% of cases reviewed fulfilled the National Center for Disease Control criteria for clinical Reye's syndrome. Causes of Reye-like syndromes/encephalo-hepatopathies included fulminant hepatitis, Japanese B encephalitis, dengue, septicaemia, and complex febrile fits. It was not possible to differentiate clinical Reye's syndrome from the other encephalo-hepatopathies by either the clinical features (except for jaundice) or biochemical parameters. Liver biopsy is necessary for a definitive diagnosis of Reye's syndrome in Malaysia, because of the high prevalence of Reye-like diseases. The mortality rate in the 2 groups of patients is similar. Ingestion of salicylates was not found to be significantly associated with Reye and Reye-like syndromes in this study.

Diagnosis, Differential↗
PubMed1990

Superadded aspergillosis on carcinoid bronchial adenoma leading to delayed diagnosis.

A review of aspergillosis in neoplastic disease revealed that most cases occur in association with malignant disorders. Amongst solid tumours it is mostly adenocarcinomas which are invaded by the fungus due to necrotic cavity formation. We here record the first reported association of aspergillosis with a benign carcinoid bronchial adenoma which was hidden by the fungal growth with a delay in diagnosis.

Aspergillosis↗
PubMed1990

Role of leukotriene C4 in pulmonary hypertension: platelet-activating factor vs. hypoxia.

The aim of this study was to determine whether leukotriene C4 (LTC4) is a mediator of hypoxic pulmonary vasoconstriction. We hypothesized that similar increases in LTC4, detected in the lung parenchyma and pulmonary vascular compartment during cyclooxygenase blockade with indomethacin (INDO), would be observed during an equal increase in pulmonary arterial pressure caused by acute alveolar hypoxia (HYP, 100% N2) or platelet-activating factor (PAF, 10 micrograms into the pulmonary artery). Rat lungs were perfused at constant flow in vitro with an albumin-Krebs-Henseleit solution. Mean pulmonary arterial pressure (n = 6 per group) increased from a base line of 10.9 +/- 1.2 to 15.8 +/- 2.1 (HYP + INDO) and 15.5 +/- 1.9 (SE) Torr (PAF + INDO). LTC4 levels increased only in response to PAF + INDO; perfusate levels increased from 0.4 +/- 0.07 to 5.3 +/- 1.1 ng/40 ml, and lung parenchymal levels increased from 1.9 +/- 0.07 to 22.8 +/- 5.3 ng/lung. Diethylcarbamazine (lipoxygenase inhibitor) reduced PAF-induced lung parenchymal levels of LTC4 by 68% and pulmonary hypertension by 63%. We conclude that 1) LTC4 is not a mediator of hypoxic pulmonary vasoconstriction and 2) intravascular PAF is a potent stimulus for LTC4 production in the lung parenchyma.

Animals↗
PubMed1990

'Solitary' Ta-T1 G1 bladder tumour--history and long-term prognosis.

Natural history of 'solitary', histological grade 1, stage Ta-T1 transitional cell carcinoma of the bladder was studied in 198 patients retrospectively over a period from 1975 to 1987. Three patterns of tumour behaviour were evident. In 56% of patients the tumour did not recur following the initial resection. Twenty-one percent developed recurrences localised to the site of the original tumour. This group became tumour-free by 5 years and remained so thereafter. The remaining 23% continued to produce recurrent tumours up to 10 years at different sites in the bladder. The actuarial percentage of patients who remained continuously free of tumour after the initial resection was 53% at 5 years and 51% at 10 years. The results of this study suggest that cytoscopic follow-up may be discontinued in patients who remain continuously tumour-free for 5 years.

Adult↗
PubMed1990

Role of lung fluid volume in growth and maturation of the fetal sheep lung.

We studied the effects of alterations in lung fluid volume on growth and maturation of the fetal lung. In a chronic fetal sheep preparation, right fetal lung volume was decreased by drainage of lung fluid while the volume of the left lung was expanded by mainstem bronchus ligation leading to lung fluid retention. After an experimental period of 25 d (from 105 to 129 d of gestation, term = 145 d), the right (deflated) lung was significantly hypoplastic and contained less DNA than the controls; 175.15 +/- 55.18 vs. 346.77 +/- 61.97 mg, respectively; P less than 0.001. In contrast, the left (expanded) lung was significantly hyperplastic and contained more DNA than the controls; 390.74 +/- 103.53 vs. 238.85 +/- 33.32 mg, respectively; P = 0.001. Biochemical indices of lung maturation, including total phospholipids, phosphatidylcholine, and disaturated phosphatidylcholine content expressed per unit of tissue DNA, were no different when comparing the hypoplastic, hyperplastic, and control lungs. These findings demonstrate that fetal lung cell multiplication is influenced by local distension with lung fluid, while the biochemical maturation of fetal lung surfactant is under systemic control.

Animals↗
PubMed1990

Three-dimensional maximum-likelihood reconstruction for an electronically collimated single-photon-emission imaging system.

A three-dimensional maximum-likelihood reconstruction method is presented for a prototype electronically collimated single-photon-emission system. The electronically collimated system uses a gamma camera fronted by an array of germanium detectors to detect gamma-ray emissions from a distributed radioisotope source. In this paper we demonstrate that optimal iterative three-dimensional reconstruction approaches can be feasibly applied to emission imaging systems that have highly complex spatial sampling patterns and that generate extremely large numbers of data values. A probabilistic factorization of the system matrix that reduces the computation by several orders of magnitude is derived. We demonstrate a dramatic increase in the convergence speed of the expectation maximization algorithm by sequentially iterating over particular subsets of the data. This result is also applicable to other emission imaging systems.

Image Processing, Computer-Assisted↗
PubMed1990

Systematic tactile error of judgment in finger-toe correspondence.

40 normal adults were tested for finger-toe correspondence identification. A systematic differential pattern of tactile judgment of errors for the five toes (with more errors in the case of the middle three toes) was obtained. The pattern was similar for both men and women and across right- and left-foot toes. These results are discussed in terms of poor sensory representation (or overlapping sensory pathways) of toes in the cerebral cortex.

Adult↗
PubMed1990

Lateralized interference in concurrent manual activity: influence of age in children.

Thirty-six right-handed bilingual children equally drawn from the two age groups of seven to nine, and eleven to thirteen years, concurrently performed a sequential finger tapping task while: (a) sitting quiet (b) reading aloud, and (c) reading aloud with an instructions to read carefully. The results showed that reading interfered more with right- than with left-hand tapping, but only in older children. The careful reading condition, however, did not add any further manual interference. The data suggest that differential right-hand tapping disruption varies with age and/or with the amount of exposure to a language or languages. These results are discussed in terms of variant and invariant cerebral asymmetry of function during childhood.

Adolescent↗