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Biomedical subjects

S Singh

Publications and source records attributed to S Singh.

At least 235 records · Page 13Linked to original sources
PubMed2001

Changing patterns of airway accidents in intubated ICU patients.

OBJECTIVE: To document the changes in patterns of airway accidents in intubated patients. DESIGN: Prospective recording of all airway accidents over two periods: 1994-1997 and 1998-1999. PATIENTS: Ventilated patients (5,046) intubated for 9,289 days over 4 years (1994-1997) and 2,932 ventilated patients intubated for 6,339 days over 2 years (1998-1999). MEASUREMENTS: The incidence and pattern of airway accidents over a 2-year period were compared to an earlier similar analysis done in the previous 4 years. RESULTS: The total accident rate in the 1994-1997 period was 36 in 5,046 patients over 9,289 intubated-patient days. The total accident rate in the period 1998-1999 was 20 in 2,932 patients over 6,339 intubated-patient days. The frequency of blocked tracheal tube increased to equal that of unplanned extubation (UE) of endotracheal tube (ETT) as the commonest airway accident. There were nine episodes of blocked tracheal tube in the two current years compared to four in the previous 4 years and there were nine episodes of UE in the two current years compared to 15 in the previous 4 years. There were a total of 18 ETT accidents in 2,930 patients over 5,309 ETT days compared to a total of two tracheostomy accidents in 67 patients over 1,030 tracheostomy days. CONCLUSIONS: We noted a change of the pattern of airway accidents. We noted an increasing trend in the incidence of blocked tracheal tubes, associated with an increased duration of heat and moisture exchanger-filters use. We also noted that the incidence of tracheostomy tube accidents was similar to that of ETT accidents in the current study, unlike the earlier study where tracheostomy tube accidents were more frequent than ETT accidents. This was due to the elimination of tracheostomy tube displacements during the later study period. We associated this with the use of adjustable tracheostomy length tubes.

Accidents↗
PubMed2001

Regulation of sodium influx in the NaCl-resistant (NaCl(r)) mutant strain of the cyanobacterium Anabaena variabilis.

A NaCl(r) mutant of the diazotrophic cyanobacterium Anabaena variabilis has been isolated by NTG mutagenesis and selection for NaCl resistance. The NaCl(r) strain has been characterized with respect to its mechanism of NaCl tolerance and regulation of Na(+) influx. NaCl(r) strain exhibits low Na(+) influx, accumulated high level of glycine betaine as a compatible solute, and persistent synthesis of SSPs at a higher rate than its wild-type counterpart. DCMU, an inhibitor of PS-II, inhibited Na(+) influx, suggesting that Na(+) influx is an energy-dependent process and that the energy is derived from photophosphorylation. This contention is further supported by the inhibition of Na(+) influx under dark conditions. The inhibition of Na(+) influx by KCN, DNP, NaN(3) also supports the involvement of oxidative phosphorylation in the regulation of active Na(+) influx. Thus, it appears that the synthesis of SSPs, accumulation of compatible solutes, and exhibition of low Na(+) influx in the NaCl(r) strain made this organism NaCl tolerant.

Anabaena↗
PubMed2001

Isolation and partial characterization of Het- Fix- mutant strain of the diazotrophic cyanobacterium Anabaena variabilis showing chromatic adaptation.

We propose a model to describe the changes taking place in biochemical processes/events to explain the development of heterocyst and nitrogenase in a diazotrophic cyanobacterium Anabaena variabilis. For this purpose, a mutant strain of A. variabilis lacking heterocyst differentiation and incapable of growth with dinitrogen as the sole source of nitrogen has been isolated after nitrosoguanidine (NTG) mutagenesis and selection by penicillin enrichment. The mutant strain (Het- Fix-) thus isolated has morphological variation and was incapable of reducing acetylene under anaerobic conditions, indicating its mutational loss of the process of nitrogen fixation. The Het- Fix- mutant strain had reduced glutamine synthetase (transferase) activity compared with its wild-type counterpart, suggesting a link between nif gene expression and the expression of gln A, the structural gene of GS. The Het- Fix- mutant strain compared with its wild-type strain also had an extremely high level of phycobiliprotein and a low level of carotenoids. Furthermore, the coiling of vegetative filaments in the Het- Fix- mutant strain, which reduced the surface area to be exposed to light, was a direct indication of the chromatic adaptation, because the mutant strain was found to be photosensitive, showing bleaching of the cells under high light intensity.

Anabaena↗
PubMed2001

Keratonconjunctivitis sicca is not uncommon in children with juvenile rheumatoid arthritis.

Keratoconjunctivitis sicca (KCS), characterised by aqueous tear deficiency, is the most common ocular complication in adult rheumatoid arthritis (RA). In juvenile rheumatoid arthritis (JRA), however, it remains under-reported. For this prospective study, 50 children with JRA were examined clinically and underwent tests for KCS (Schirmer's I and rose bengal tests, fluorescein staining, and tear film breakup time). Six children (12%) with two or more abnormal tests were diagnosed as having definite KCS, while one child with only one abnormal test was labelled with probable KCS. Five of the six (83.3%) with definite KCS were males, and three (50%) had a pauciarticular form of the disease. Two children (33.3%) with definite KCS had no ocular symptoms, five were receiving only nonsteroidal anti-inflammatory drugs, and one was additionally on methotrexate. Keratoconjunctivitis sicca appears to be a common ocular complication and all children with JRA should be screened for it with a comprehensive battery of tests.

Adolescent↗
PubMed2001

Gene expression profile of ARPE-19 during repair of the monolayer.

BACKGROUND: The purpose of this study was to identify the profile of gene expression during retinal pigment epithelial (RPE) wound repair. METHODS: ARPE-19 cells derived from a human RPE cell line were grown for 4 weeks and injured by creating multiple concentric wounds. Unwounded cultures served as controls. During the proliferative phase of wound repair, total RNA was extracted from control and wounded cultures, and a [32P]dATP-labeled cDNA probe was synthesized and hybridized to Atlas Arrays (Clontech, Palo Alto, Calif.) containing 588 cDNAs. The autoradiograms obtained were then analyzed using the Molecular Dynamics software program. Semiquantitative PCR was carried out to confirm up-regulation of four genes associated with wound repair. ELISA was performed to quantitate the secreted MCP-1. RESULTS: In wounded cultures prominent up-regulation (greater than fivefold) was seen for genes encoding DNA synthesis and DNA repair proteins. A greater than threefold increase was seen for genes encoding mitogen-activated protein kinase, CD44, MCP-1 (monocyte chemotactic protein), thymosin beta-10, and HDGF (hepatoma-derived growth factor), among others. Genes encoding tumor suppressors were downregulated three- to five-fold in the wounded compared with the unwounded cultures. Semiquantitative PCR confirmed up-regulation of transcripts for thymosin beta-10, HDGF, CD44, and MCP-1. ELISA showed a 20% increase in secreted MCP-1. CONCLUSIONS: Gene array analysis revealed a differentiation program that included increased expression of genes involved in wound repair (adhesion molecules, cytokines, signal transducers), along with increased MCP-1 secretion. The RPE may be an early participant in the inflammatory response that occurs with proliferative vitreoretinopathy.

Cells, Cultured↗
PubMed2001

Transgenic expression of a delta 12-epoxygenase gene in Arabidopsis seeds inhibits accumulation of linoleic acid.

The Crepis palaestina cDNA Cpal2 encodes a delta 12-epoxygenase that can catalyse the synthesis of 12,13-epoxy-cis-9-octadecenoic acid (18:1E) from linoleic acid (18:2). When the Cpal2 gene was expressed under the control of the napin seed-specific promoter in Arabidopsis thaliana (L.) Heynh., the seed lipids accumulated only low levels of 18:1E and also 12,13-epoxy-cis-9,15-octadec-2-enoic acid (18:2E). Despite the fact that the levels of these epoxy fatty acids comprised only up to 6.2% of the total fatty acids, there was a very marked increase in oleic acid (18:1) and decrease in linoleic (18:2) and alpha-linolenic (18:3) acids in these plants, indicating that endogenous delta 12-desaturation was greatly reduced in these plants. Significant between-line differences in the levels of Cpal2 mRNA were observed during seed development, but were not associated with any major variation in mRNA levels for the endogenous Arabidopsis delta 12-desaturase (Fad2). This suggests that if an unfavourable interaction occurs between the transgenic delta 12-epoxygenase and the endogenous delta 12-desaturase, which decreases the level of desaturation, it occurs at either the translational or post-translational level. We further show that the co-expression of a delta 12-desaturase gene from C. palaestina in Cpal2 transgenic Arabidopsis returns the relative proportions of the C18 seed fatty acids to normal levels and results in an almost twofold increase in total epoxy fatty acids.

2S Albumins, Plant↗
PubMed2001

Hemiplegic/monoplegic presentation of cervical spine (C1-C2) tuberculosis.

Tuberculosis of the craniovertebral region is very rare. Neural deficit in this region is reported in between 24% and 64% of cases, and mainly takes the form of quadriparesis. Hemiplegic and monoplegic presentation among this set of patients is rarer. Out of 32 patients treated at our institution between May 1989 and February 2001, only one had hemiplegia, while two had monoplegia. These three cases are discussed. Case 1 involved a 45-year-old woman who presented with hemiplegia following a trivial fall. Plain radiographs and computed tomographic (CT) scans of the skull appeared normal, but CT scans of C1-C2 and the craniovertebral junction revealed destruction of the dens and atlantoaxial subluxation. The patients in cases 2 and 3 had monoplegia. Plain radiographs in both cases showed an increased prevertebral soft tissue shadow in front of C1-C2. CT in case 2 and magnetic resonance imaging (MRI) in case 3 revealed destruction of the arch of C1 and the dens, with subluxation. All three patients were successfully treated with rest, skull traction, anti-tubercular drugs and suitable braces. Case 3 required stabilization. All three patients achieved complete neural recovery. Patients 1, 2 and 3 had 22, 48 and 4 months' follow-up respectively. Patient 3 was subsequently transferred to a neurosurgery ward for stabilization of the occipito-C3 vertebrae. Hemi/monoplegic presentation is extremely rare; no author in the literature is able to give reason for the rarity or the pathomechanics of the condition. We believe that if medullary cervical junctional involvement extends slightly higher (in rare circumstances), with involvement of one of the branches of the vertebral or lower basilar artery, medial medullary syndrome will occur, sparing medial lemniscus and emerging hypoglossal nerve fibres. Thus the pyramids will be involved, causing contralateral hemiparesis, and if the pyramids are selectively involved, it will cause contralateral monoparesis.

Adult↗
PubMed2001

Natural and artificial substrates for retinal pigment epithelial monolayer transplantation.

The aim of this study was to culture retinal pigment epithelial (RPE) cells on natural and synthetic substrates for future use in RPE monolayer transplantation in the eye. The extracellular capsules surrounding the human lens and a hydrogel biomaterial were used as substrates for monolayer culture. All materials were seeded with either pig or human retinal pigment epithelial cells and were maintained in tissue culture conditions. Upon confluency, the cell density was calculated and cell viability determined. All monolayers were stained with phalloidin-rhodamine for F-actin and antibodies to tight junction-associated protein, ZO1. The final cell density of human RPE monolayers on the hydrogel and lens capsule was 3,200 +/- 187 and 3,350 +/- 120 cells/mm2 respectively. Pig RPE cells had a final cell density of 3,740 +/- 20 5cells/mm2 on the lens capsule and 3,025+ cells/mm2 on the hydrogel. F-actin staining revealed a circumferential ring of actin filaments in all the cells grown on substrates. ZO1 immunohistochemisty demonstrated staining along the lateral cell borders of all cell types. The successful culture of RPE cells on these substrates may have the potential for transplanting cell monolayers in the eye to improve outcomes for degenerative diseases in the retina.

Actins↗
PubMed2001

Low risk of significant echocardiographic valvulopathy in patients treated with anorectic drugs.

BACKGROUND: Phentermine--fenfluramine and dexfenfluramine use for weight loss has been previously associated with increased prevalence of valvular heart disease. This association was initially based on small numbers of patients, limited data on dose and duration of drug therapy, and no correlation with matched controls. METHODS: Our investigation involved 343 obese subjects enrolled in a prospective, strict weight loss, research protocol from September 1994 to September 1997. All subjects underwent transthoracic echocardiography for significant valvular lesions within a mean of 121 days from the manufacturer's announcement of the voluntary withdrawal of fenfluramine and dexfenfluramine from the market. All echocardiograms were interpreted by 2 independent readers. RESULTS: The study population included 281 females and 62 males with a mean age of 46.7+/-9.1 years and mean initial body mass index of 40.1+/-8.1 kg/m(2). Using the Food and Drug Administration's criteria, only 21 subjects (6.1%) had significant valvular lesions. Aortic regurgitation was detected in 18 subjects, mitral regurgitation in 3 subjects, and both aortic and mitral regurgitation in 1 subject; no one had severe regurgitation. Significant valvular disease did not correlate with age, gender, initial/ending body mass index, the drug dose, duration of drug therapy, or serotonin reuptake inhibitors. CONCLUSIONS: Anorexigen therapy is associated with a low prevalence of significant valvular regurgitation. Late valvular abnormalities from drug treatment await long term prospective studies.

Aortic Valve Insufficiency↗
PubMed2001

Hepatic and renal metallothionein induction by an oral equimolar dose of zinc, cadmium or mercury in mice.

The hepatic and the renal subcellular distribution of zinc, cadmium or mercury and induction of tissue metallothionein (MT) at 24, 48 and 72 h following an oral equimolar dose (15 micro;mol metal/kg) of zinc (II) chloride, cadmium (II) chloride or mercury (II) chloride in male albino mice were investigated. There was a moderate increase in hepatic and renal zinc levels mainly in their nuclear mitochondrial fraction (NMF) 24 h post zinc chloride administration. Subsequently, the hepatic zinc increased and the renal zinc declined with time. The zinc-induced hepatic MT level was maximum at 48 h, which decreased slightly thereafter, while there was no marked increase in renal MT level at any time interval. The cadmium was equally distributed in liver and kidney more in their supernatant cytosol fraction (SCF) than in their NMF at 24 h after a dose of cadmium chloride. The cadmium levels showed a decreasing trend in hepatic fractions and an increasing trend in renal fractions with time. The cadmium-induced hepatic and renal MT were substantial at 24 h post cadmium administration, the former decreased thereafter while the latter enhanced at 48 h before declining. The accumulation of mercury in kidney was 1.5 times that in liver, which was localised more in their SCF than in their NMF at 24 h in response to a dose of mercuric chloride. The mercury levels of hepatic and renal subcellular fractions started declining after 24 h and at 72 h they were significantly lower. The induction of hepatic and renal MT was maximum at 24 h after mercuric chloride administration, which declined thereafter concomitant with the decrease in their mercury levels. However, the MT levels in both the organs remained considerably higher than in normal animals at 72 h post exposure. The results show that the accumulation of metal in liver and kidney follows the order: Hg > Cd > Zn and the induction of MT follows Hg > Cd > Zn in liver and Cd > Hg > Zn in kidney. The alterations in zinc and copper homeostasis were more marked in liver than in kidney and follows the order: Hg > Cd > Zn.

Animals↗
PubMed2001

Evaluation of the gastric antiulcerogenic effect of large cardamom (fruits of Amomum subulatum Roxb).

Large cardamom (fruit of Amomum subulatum Roxb, N.O. Zingiberaceae) commonly known as 'Heel kalan' or 'Bari Ilaichi' is used in Unani system of medicine in gastrointestinal disorders. A crude methanolic extract and its different fractions, viz. essential oil, petroleum ether (60-80 degrees ), ethyl acetate and methanolic fractions, were studied in rats for their ability to inhibit the gastric lesions induced by aspirin, ethanol and pylorus ligature. In addition their effects on wall mucus, output of gastric acid and pepsin concentration were recorded. The crude methanolic extract of A. subulatum and its fractions, viz. essential oil, petroleum ether and ethyl acetate, inhibited gastric lesions induced by ethanol significantly, but not those which were induced by pylorus ligation and aspirin. However, ethyl acetate fraction increased the wall mucus in pylorus ligated rats. The results suggest a direct protective effect of ethyl acetate fraction on gastric mucosal barrier. While the observation of decrease in gastric motility by essential oil and petroleum ether fractions suggests the gastroprotective action of the test drug. These investigations validate the use of 'Heel kalan' in gastrointestinal disorders by Unani physicians.

Animals↗
PubMed2001

Influence of Podophyllum hexandrum on endogenous antioxidant defence system in mice: possible role in radioprotection.

Podophyllum hexandrum, a Himalayan herb with known radioprotective and anti-tumour properties, was investigated for its mechanism of action. Glutathione S-transferase (GST), catalase, superoxide dismutase (SOD) activities and lipid peroxidation (LPx) were determined in the liver, jejunum and ileum at various time intervals, with and without the aqueous extract of P. hexandrum rhizome (200 mg/kg b.w. i.p.) in unirradiated and whole body irradiated (10 Gy,-2 h) male Swiss albino mice. Pre-irradiation treatment with P. hexandrum enhanced liver GST (P<0.01) and SOD (P<0.05) at 12 h post irradiation, the intestinal SOD (P<0.00005) at 84 h post irradiation was significantly elevated. However, no significant change was manifested in the catalase activity in the liver, at any of the post irradiation intervals (0, 12 and 84 h). The antioxidant defence with Podophyllum sp. treatment in mice can explain to some extent its protective action manifested in terms of survival against whole body lethal irradiation. However, some other possible mechanisms that may strengthen radioprotective action of the Podophyllum sp. extract need to be investigated further.

Animals↗
PubMed2001

Effect of Ocimum sanctum fixed oil on blood pressure, blood clotting time and pentobarbitone-induced sleeping time.

Ocimum sanctum fixed oil produced hypotensive effect in anaesthetised dog, which seems to be due to its peripheral vasodilatory action. The oil increased blood-clotting time and percentage increase was comparable to aspirin and could be due to inhibition of platelet aggregation. The oil also increased pentobarbitone-induced sleeping time in rats indicating probable inhibitory effect of oil towards cytochromic enzyme responsible for hepatic metabolism of pentobarbitone.

Animals↗
PubMed2001

The ICH guidance in practice: stress degradation studies on ornidazole and development of a validated stability-indicating assay.

The present study describes degradation of ornidazole under different ICH prescribed stress conditions (hydrolysis, oxidation and photolysis), and establishment of a stability-indicating reversed-phase HPLC assay. Degradation was found to occur in alkaline medium, under high acidic conditions, under oxidative stress, and also in the presence of light in acid conditions. Previously the drug is only known to decompose under alkaline conditions. Separation of drug and the degradation products under various conditions was successfully achieved on a C-18 column utilising water-acetonitrile in the ratio of 86:14. The detection wavelength was 310 nm. The method was validated with respect to linearity, precision, accuracy, selectivity, specificity and ruggedness. The response was linear in the drug concentration range of 5-500 microg ml(-1). The mean values (+/-RSD) of slope, intercept and correlation coefficient were 45251 (+/-1.59), 104418 (+/-2.49) and 0.9996 (+/-0.03), respectively. The RSD values for intra- and inter-day precision studies were <1 and <2.6%, respectively. The recovery of the drug ranged between 100-103% from a mixture of degradation products. The method was specific to drug and also selective to degradation products.

Chromatography, High Pressure Liquid↗
PubMed2001

Increased biogas production using microbial stimulants.

Laboratory studies were undertaken to evaluate the effect of microbial stimulants Aquasan and Teresan, on biogas yields from cattle dung and combined residues of cattle dung and kitchen waste, respectively. The addition of single dose of Aquasan at the rate of 10, 15 and 20 ppm to cattle dung on the first day of incubation resulted in increased gas yields ranging between 45.1 and 62.1 l/kg dry matter. Subsequent addition of Aquasan at 15 and 20 ppm dosage after a period of 15 days increased the gas yields by 15-16%. The gas production was found to be optimum at a dosage level of 15 ppm and was 39% and 55% higher with single and dual additions, respectively, than untreated cattle dung. In another bench scale study (1:1 dry matter) the addition of Teresan at 10 ppm concentration to the mixed residues of cattle dung and kitchen wastes at different solids concentration, produced 34.8% more gas (272.4 l/kg d.m.) than the uninoculated mixture at 15% TS concentration (202.4 l/kg d.m.).

Anaerobiosis↗
PubMed2001

The health status of obese individuals in Canada.

OBJECTIVE: To determine whether there is a clinically relevant difference in the health state utilities of obese and non-obese individuals as measured by the Health Utility Index Mark III. METHODS: Secondary analysis of the population-based, cross-sectional, interviewer-administered National Population Health Survey (NPHS), 1996-1997. A probability sample of house-dwelling Canadians, excluding populations on First Nations Reserves, Canadian Armed Forces Bases, the Yukon and Northwest Territories, and long-term residents of hospitals or residential care facilities. The sub-sample used in this analysis consisted of 38 151 respondents (52.4% male) between the ages of 20 and 64 y, excluding pregnant women. Health Utilities Index-Mark III (HUI3) scores were used to define normal weight (body mass index (BMI) 19-24.9 kg/m(2)), overweight (BMI 25-29.9 kg/m(2)), obese (BMI 30-34.9 kg/m(2)), and morbidly obese (BMI> or =35 kg/m(2)) individuals. HUI3 scores were age- and gender-standardized. RESULTS: The overall prevalence of obesity (BMI> or =30 kg/m(2)) in this Canadian population was 13.3%. The average difference in HUI3 scores between normal weight and morbidly obese respondents was 0.04 (P<0.001). Statistically significant (P<0.05) differences across BMI categories were found in each of the eight component attributes of the HUI3. The attributes with the most substantial difference between normal and obese patients were cognition, mobility and pain. All demonstrated a > or =2-fold increase in the proportion of individuals in poorer classifications of health when normal weight respondents were compared with the morbidly obese. The magnitude of the decrement in utility ratings associated with obesity was comparable with other chronic non-cardiovascular conditions such as migraine or colitis. CONCLUSION: The results indicate that changes in self-rated health status appear to be due to significant changes across several relevant domain attributes. Obesity has a significant impact on both quality of life and health.

Adult↗
PubMed2001

A survey of pre-operative optimisation of high-risk surgical patients undergoing major elective surgery.

Pre-operative optimisation of high-risk patients undergoing major elective surgery has been shown to decrease peri-operative morbidity and mortality. It is also cost effective because of the resulting decrease in postoperative complications. A questionnaire was sent to 170 intensive care and high dependency units in Britain in order to quantify the number of units practising pre-operative optimisation. There was a 91% response rate. Of the respondents familiar with the evidence advocating pre-operative optimisation, 91% believe pre-operative optimisation improves outcome but only 62% admit patients for such preparation. Moreover, only eight units (6%) admit more than 25% of eligible patients. The reasons given for not admitting such patients pre-operatively are a lack of manpower, beds or both. This survey demonstrates the need for greater investment of resources into intensive care and high dependency units, so that clinicians can deliver high-quality evidence-based healthcare in accordance with the principles of clinical governance.

Elective Surgical Procedures↗