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Biomedical subjects

N Singh

Publications and source records attributed to N Singh.

At least 271 records · Page 15Linked to original sources
PubMed1998

Pulmonary infiltrates in the surgical ICU: prospective assessment of predictors of etiology and mortality.

A prospective cohort study of 129 consecutive patients developing pulmonary infiltrates in the surgical ICU was conducted to determine the predictors and outcome of pulmonary infiltrates. Most common etiologies of pulmonary infiltrates were pneumonia (30%), pulmonary edema (29%), acute lung injury (15%), and atelectasis (13%). Enteral nutrition was associated with a significantly lower incidence of acute lung injury as compared with pneumonia (22% vs 58%, p = 0.012). Patients with liver disease were significantly more likely to have pulmonary infiltrates due to acute lung injury as compared with other etiologies (p = 0.02). Clinical pulmonary infection score (Pugin score) > 6 virtually excluded acute lung injury, pulmonary edema, or atelectasis as etiologies of pulmonary infiltrates. Nosocomial Haemophilus/pneumococcal pneumonia occurred significantly earlier in the ICU as compared with Gram-negative (p = 0.05) or methicillin-resistant Staphylococcus aureus pneumonia (p = 0.01). Pneumonia in trauma patients was significantly more likely to be due to Haemophilus/pneumococcus as compared with all other ICU patients (54% vs 0%, p = 0.0004). These data have implications for treatment of patients with nosocomial pneumonia in the ICU.

APACHE↗
PubMed1998

Fine-needle aspiration cytology of lepromatous leprosy.

A prospective study correlating cytopathology with clinical morphology and histopathology in 22 patients with lepromatous leprosy was performed. Aspirates were taken from skin lesions in all patients. Lymph node aspirates were also performed in four patients with lymphadenopathy. Fine-needle aspirates yielded sufficient cellular material with excellent preservation of morphological detail. Diagnosis and correlation with bacillary index, clinical and histopathological findings was possible in all patients. In addition, the two patterns, partial and diffuse, of lymph node involvement could be recognized. Fine-needle aspiration cytology is a simple method for the laboratory assessment of leprosy.

Biopsy, Needle↗
PubMed1998

Differential in vitro modulation of Schwann cell proliferation by Mycobacterium leprae and macrophages in the murine strains, Swiss white and C57Bl/6.

The special susceptibility of Schwann cells (SCs) to parasitization by M. leprae and of macrophages to M. leprae-induced defects implicates them in leprous nerve pathogenesis. SC proliferation is an important prerequisite for peripheral nerve regeneration and is regulated by a number of secretory factors. Several of these factors are secreted by SCs themselves as well as by the macrophages which are recruited at the site of lesion to assist in regeneration. SC proliferation, as indicated by 3H-thymidine incorporation, was therefore studied in response to M. leprae infection and in the presence of macrophages in order to determine the role of SC in leprous neuropathy. Cells derived from two strains of mice, Swiss White (SW) and C57Bl/6 were used, as macrophages from these strains have been shown to differ in their response to M. leprae; such differences are similar to those observed in macrophages from lepromatous and tuberculoid leprosy patients, respectively. Infection with M. leprae for a duration of 9 days resulted in reduced proliferation of SCs from SW strain, while SCs from C57Bl/6 remained unaffected. However, in the presence of macrophages, SCs from both strains not only showed enhanced proliferation, but SW SCs also overcame the M. leprae-induced suppression of their proliferation. Altered SC proliferation, therefore, can be implicated as a factor in leprous nerve pathogenesis. The strain variation observed in the response of SCs indicate different nerve damage mechanisms in lepromatous and tuberculoid patients.

Animals↗
PubMed1998

Infectious diseases in the liver transplant recipient.

Despite a declining incidence, infections remain a significant complication in liver transplant recipients. The spectrum of infections in transplant recipients, however, appears to be evolving. Infections caused by gram-positive bacteria (e.g., enterococci and staphylococci) have now surpassed in frequency those caused by gram-negative bacteria. There has been a decline in the incidence of Pneumocystis carinii and more recently cytomegalovirus infection in transplant recipients, largely as a result of effective prophylaxis. Opportunistic fungal infections (e.g., aspergillosis) remain problematic. New or previously unrecognized pathogens (e.g., human herpesvirus-6) may also be a significant cause of morbidity. Evaluation of infections in transplant recipients therefore requires understanding of not only classic opportunistic infections typically encountered in these patients, but also emerging trends in epidemiology, prophylaxis, and management.

Bacteremia↗
PubMed1998

Insight on emphysema--the first 300 cases of surgical treatment.

Our experience with lung volume reduction surgery for emphysema now encompasses more than 300 cases, including several prospective trials. We have a 3.5% operative mortality rate and, with aggressive use of Heimlich valves over the past 6 months, an average hospital length of stay of 8 days. Proper patient selection is essential and can be based primarily on results of pulmonary function tests (PFTs), ventilation/perfusion (V/Q) scans, and computed tomography (CT) scans. We have found that bilateral is more effective than unilateral staple lung volume reduction surgery, which is in turn better than unilateral laser surgery. In patients with bilateral upper lobe disease, average FEV1 (forced expiratory volume in a 1-second interval) improvement is 82%; overall, it is 61% (range -33 to 217%). We conclude that lung volume reduction surgery can be performed safely with acceptable mortality and excellent clinical results in properly selected, motivated patients.

Aged↗
PubMed1998

Studies on malaria during pregnancy in a tribal area of central India (Madhya Pradesh).

In tribal villages of central India where malaria is highly prevalent (mesoendemic), this preliminary study was undertaken to determine the effects of malaria infection in a group of 456 pregnant women with or without fever. Only 96 women were found infected with malaria, of which Plasmodium falciparum accounted for 64% of the detected parasites, while P. vivax for the remaining 36%. There were no instances of cerebral malaria or death however, one abortion and four still births were recorded among 38 primigravid women. Only one neonate was found infected with P. falciparum on day 21 though parasitemia was not high. Anemia was commonly present in most of the women (80%). Failure to clear P. falciparum parasitemia after a chloroquine regimen (25 mg/kg of body weight) was commonly observed. Persistent P. falciparum parasitemia was recorded in 8% cases. Poor response to chloroquine suggests the need to change the drug policy.

Adult↗
PubMed1998

In vitro studies on extracellular matrix production by M.leprae infected murine neurofibroblasts.

Fibroblasts and a host of macrophage secretory products have been implicated in a number of diseases where excess extracellular matrix (ECM) deposition is the main pathological feature. Fibrosis characterized by excessive deposition of collagen also contributes to the irreversible nerve damage observed in leprosy. Since M. leprae are seen within neurofibroblasts (Nf) in the advanced stages of the disease and macrophages form a common infiltrating cellular constituent of leprous nerves at all stages, secretion of ECM proteins by Nf was studied, in vitro following infection with M. leprae and in the presence of macrophage secretory products. These studies were compared in cells derived from two strains of mice, Swiss White (SW) and C57BL/6, as they differ in their response to M. leprae infection and parallel those observed in lepromatous and tuberculoid patients, respectively. On infection with M. leprae, Nfs showed a decrease in secretion of collagen type IV in SW and type I in C57Bl/6 strain. Macrophages caused a further decrease in the secretion of collagen types affected by M. leprae infection per se, while the other collagen types, viz. I and III in SW strain and III and IV in C57Bl/s strain, were unaffected. This study indicates that neural collagenization in nerves in advanced leprosy may be of Nf origin. However, unlike other diseases with excess collagen deposition, ECM proteins produced by Nfs in response to nerve damage may not be of prime importance in the progression of leprous neuropathy and occur as a general response to loss of cellular content in leprous nerves.

Animals↗
PubMed1998

The effect of early ambulation on hematoma formation and vascular complications following 7 French diagnostic cardiac catheterization.

OBJECTIVE: To assess the feasibility and safety of early ambulation 3 to 4 h after diagnostic 7 French cardiac catheterization. DESIGN: Randomized, single-blind assignment to one of 3, 4 or 6 h ambulation postcardiac catheterization groups. SETTING: Tertiary care community hospital in an urban region. PATIENTS: Eight hundred and seventy-four consecutive inpatients and out-patients presenting for routine diagnostic cardiac catheterization. INTERVENTION: Hematoma formation and other vascular complications recorded at the time of discharge and 24 h later. MAIN RESULTS: No significant difference in hematoma formation rates was noted among patients mobilized at 3 h (3.6%), 4 h (4.8%) or 6 h (3.2%). Late hematoma formation occurred in 2.3% of patients. Other vascular complications were very rare. Reported rates of hematoma formation varied significantly (P < 0.05) among physicians, ranging from 0.9% to 8.0%. CONCLUSIONS: Early ambulation of patients 3 to 4 h after routine diagnostic 7 French cardiac catheterization is both safe and feasible. These findings could result in more efficient recovery bed utilization, reduced nursing costs and improved patient compliance with bed rest.

Anticoagulants↗
PubMed1998

Effectiveness of alpha-beta arteether in clearing Plasmodium falciparum parasitemia in central India (Madhya Pradesh).

Forty-six patients (25 Females + 21 Males) of uncomplicated Plasmodium falciparum in districts Jabalpur and Mandla of central India (Madhya Pradesh) were administered alpha-beta arteether (an ethyl derivative of qinghaosu), intramuscularly for 3 consecutive days (150 mg once a day). The results revealed that there was rapid control of fever in all the patients without administration of any antipyretic drug. The mean parasite clearance time was 30.78 +/- 10.92 hours and recrudescence/reinfection rate was 6.7% within 28 days. Study indicates that arteether, besides being a potent and fast acting schizontocidal drug, also exhibited gametocytocidal action on P. falciparum.

Adolescent↗
PubMed1998

Brucellosis in north India: results of a prospective study.

Human brucellosis is a significant public health problem in India, the magnitude of which is not known. Paucity of clinico-epidemiologic data hampers control strategies. We prospectively studied 121 cases of fever of unknown origin (FUO) and 50 occupationally exposed individuals. Four patients with FUO had acute brucellosis (3.3%) while 8 (6.6%) had serological evidence of previous brucella infection. Seven of the 50 (14%) asymptomatic, 'at risk' individuals screened were seropositive for brucella. Persistence of the animal reservoir of infection, low physician awareness, poor availability of diagnostic facilities, and the non existence of regional data bases contribute towards the perpetuation of this zoonosis in India, while it has been eradicated from most developed countries.

Adult↗
PubMed1997

Prion protein aggregation reverted by low temperature in transfected cells carrying a prion protein gene mutation.

Prion diseases are characterized by the conversion of the normal cellular prion protein (PrPC), a glycoprotein that is anchored to the cell membrane by a glycosylphosphatidylinositol moiety, into an isoform that is protease-resistant (PrPres) and pathogenic. In inherited prion diseases, mutations in the prion protein (PrPM) engender the conversion of PrPM into PrPres. We developed a cell model of Gerstmann-Sträussler-Scheinker disease, a neurodegenerative condition characterized by PrPM-containing amyloid deposits and neuronal loss, by expressing the Gerstmann-Sträussler-Scheinker haplotype Q217R-129V in human neuroblastoma cells. By comparison to PrPC, this genotype results in the following alterations of PrPM: 1) expression of an aberrant form lacking the glycosylphosphatidylinositol anchor, 2) increased aggregation and protease resistance, and 3) impaired transport to the cell surface. Most of these alterations are temperature-sensitive, indicating that they are due to misfolding of PrPM.

Cell Membrane↗
PubMed1997

Schwann cell extracellular matrix protein production is modulated by Mycobacterium leprae and macrophage secretory products.

Extracellular matrix (ECM) protein deposition is an important feature of leprous nerves, where Schwann cells (SCs) and macrophages are the main hosts for Mycobacterium leprae. Since, SCs are involved in the synthesis of ECM proteins and its production is regulated by macrophage secretory factors, the present study aimed to determine in vitro, the effect of M. leprae infection and macrophage secretory products on secretion of ECM proteins by SCs in two strains of mice, Swiss White (SW) and C57BL/6, that are known to differ in their nerve pathology and macrophage functions in response to infection. Following six days of M. leprae infection, SCs from SW mice responded with increased secretion of 14C-leucine radiolabelled proteins and a concomitant increase in laminin and collagens type I, III and IV, as determined by enzyme-linked immunosorbent assay. In contrast infected C57BL/6 SCs responded with decreased secretion of total proteins and fibronectin. Exposure of SCs to macrophage conditioned medium resulted in decreased ECM protein secretion in both strains of mice. This decrease was a function of protein breakdown by macrophage derived proteases and also active regulation by macrophage secreted cytokines. A similar effect of M. leprae and macrophage secretory products on SC metabolism in leprous nerves would have major ramifications on damage and repair activities. In addition ECM proteins would also influence the composition of the infiltrating cell population in lepromatous and tuberculoid nerves.

Animals↗
PubMed1997

Mutation of the Stargardt disease gene (ABCR) in age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of severe central visual impairment among the elderly and is associated both with environmental factors such as smoking and with genetic factors. Here, 167 unrelated AMD patients were screened for alterations in ABCR, a gene that encodes a retinal rod photoreceptor protein and is defective in Stargardt disease, a common hereditary form of macular dystrophy. Thirteen different AMD-associated alterations, both deletions and amino acid substitutions, were found in one allele of ABCR in 26 patients (16%). Identification of ABCR alterations will permit presymptomatic testing of high-risk individuals and may lead to earlier diagnosis of AMD and to new strategies for prevention and therapy.

ATP-Binding Cassette Transporters↗