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Biomedical subjects

G Singh

Publications and source records attributed to G Singh.

At least 91 records · Page 5Linked to original sources
PubMed2002

Malignant ascites fluid (MAF), including ovarian-cancer-associated MAF, contains angiostatin and other factor(s) which inhibit angiogenesis.

OBJECTIVE: The aim was to determine whether human malignant ascites fluid (MAF) associated with abdominal cancer, including ovarian cancer, contained factors which inhibit angiogenesis as well as others which stimulate this process. METHODS: MAF was collected from six patients, four with ovarian cancer, one with gastric cancer, and one with liver metastases. Using the chick chorioallantoic membrane (CAM) the effect of MAF on 7-day-old CAM capillaries was examined for 48 h. Vascular endothelial growth factor (VEGF) was evaluated by ELISA. Five samples of MAF were fractionated by lysine-Sepharose chromatography and the lysine-bound and -unbound fractions were eluted by epsilon-amino-n-hexanoic acid. Whole MAF, the lysine-bound and -unbound fractions, and human angiostatin were subjected to SDS-PAGE/Western blot analysis and immunostained after exposure to anti-human plasminogen. Human plasminogen was exposed to conditioned medium from ovarian epithelial cancer (HEY) cells and subjected to similar Western blot analysis. RESULTS: Despite containing VEGF, each MAF sample examined caused a loss of capillaries from the CAM; a similar response was seen using purified human angiostatin. Whole MAF and the lysine-bound fraction contained plasminogen (90 kDa) and a 55-kDa protein which migrated in a similar manner to human angiostatin on Western blot. Both the lysine-bound and -unbound fractions caused a loss of capillaries in the CAM. Human plasminogen exposed to conditioned medium from HEY cells yielded a fragment which was similar in size to angiostatin. CONCLUSIONS: MAF from patients with various clinical presentations contains angiostatin and VEGF as well as other factors which are capable of inhibiting angiogenesis.

Adult↗
PubMed2002

Pregnancy in patients with spina bifida and urinary diversion.

With better medical care the mortality and morbidity associated with spina bifida are improving and more such patients are reaching reproductive age. Significant problems may be encountered in the management of pregnancy in spina bifida, especially in patients with previous abdominal operations for the management of neuropathic bladder dysfunction. We report successful pregnancy outcomes in 2 such patients, both with urinary diversions, with combined obstetric and urological care. We also review the existing literature on the subject.

Adult↗
PubMed2002

The quality of obstetrical clinical practice guidelines promulgated by a specialty society.

OBJECTIVE: To review the methodologic quality of all obstetrical clinical practice guidelines developed by the Society of Obstetricians and Gynaecologists of Canada (SOGC) from 1992 to August 2001. METHODS: Three reviewers independently assessed each of 37 guidelines according to a validated and reliable 37-item appraisal tool. A mean "global" score as well as three "dimension" scores were calculated for each guideline. The appraisal tool assessed each document according to three dimensions, which related to the rigour of its development (Dimension 1), its context and content (Dimension 2), and its application (Dimension 3). A repeated-measures analysis of variance was used to derive the interclass correlation coefficient. RESULTS: Mean global quality scores ranged from 8.1% to 54.0%. Only two guidelines were given a mean global score above 50% and 21 of the guidelines (56.8%) had mean global scores of less than 30%. Mean dimension scores were 19.9% for Dimension 1, relating to rigour of development, 47.3% for Dimension 2, relating to context and content, and 27.2% for Dimension 3, relating to application. The interclass correlation coefficient using a fixed-effects model was 0.72, reflecting reasonable agreement between the reviewers. CONCLUSION: Both the mean global scores and mean dimension-specific scores for the obstetrical clinical practice guidelines were lower than optimal. We were unable to reveal statistically significant improvements in guideline quality over time given the limited number of documents, but the scores for more recently drafted guidelines appear generally higher than earlier guidelines. This finding is consistent with new editorial policy adopted by the SOGC regarding guideline development. A broader review should be conducted by the SOGC on guidelines in development and under revision.

Canada↗
PubMed2002

Morphological, histomorphometric, and microstructural alterations in human bone metastasis from breast carcinoma.

Bone is one of the most common sites of breast cancer metastasis. Metastases are often associated with bone destruction and are a major cause of morbidity. We examined structural bone changes induced by metastatic tumor in bone biopsies from 33 patients with metastatic breast carcinoma (20 from patients with pathological femoral fracture and 13 with no fracture) and 20 normal controls. In all metastatic biopsies bone remodeling was shown to be tumor volume-dependent. Bone resorption and bone formation were biphasic with both increasing at earlier stages of metastatic bone disease and decreasing later on. A comparison of patients with fracture and no fracture did not reveal statistically significant differences in the extent of bone destruction or trabecular thinning. Bone histomorphometry showed limited ability to explain the higher bone volume loss in fracture patients (decreases of 42% and 25%, respectively, in fracture and nonfracture patients compared with controls). However, changes in bone quality, including increased disconnectivity and decreased connectivity, as evaluated by node-strut analysis, suggested that there were more structural changes in the fracture compared with the nonfracture group. The nonfracture group included six patients with no radiological evidence of bone metastasis (occult metastasis). They showed a higher tumor volume and a twofold lower eroded surface compared with the rest of the group. The decrease in bone volume (14% lower than controls) was below the limit of X-ray detection. Because we observed no increase in osteoclast-related parameters and no correlation between osteoclast surface and eroded surface, we believe that, in occult metastasis, osteoclastic bone resorption is not an important factor in overall bone resorption. Quantitatively, the eroded surface in direct contact with tumor cells was threefold higher than the osteoclast surface in occult metastasis, whereas the rest of the metastatic group (27 of 33) showed predominantly osteoclast-mediated eroded surface. Node-strut analysis on occult metastasis revealed a significant increase in disconnectivity without a concomitant significant decrease in bone volume and trabecular thinning. We conclude that, in occult metastasis, bone resorption may be more osteoclast-independent and other mechanisms involving the tumor cells may be more prevalent.

Adult↗
PubMed2002

Changes in grazing behaviour of native and crossbred sheep in different seasons under semi-arid conditions.

Thirty-four non-pregnant 2-year-old ewes (17 Chokla (native) and 17 Avivastra (67.5% Chokla and 32.5% Rambouillet), of similar body weight, were maintained under the same management conditions with 8 hours daily grazing in an area with bushes, trees and miscellaneous other forage. The periods of active grazing, resting, resting while standing and lying, ruminating while standing or lying, walking time while grazing and bites per minute were recorded. The resting time differed significantly between the breeds, except in the winter. Both breeds spent more time standing during the summer and least during the spring. The crossbred animals spent more time lying in all the seasons except in the rainy season and almost the same pattern was observed for rumination time. A higher bite rate occurred in the crossbred ewes during the rainy and winter seasons, this being three times more than that for the native ewes.

Animals↗
PubMed2002

Atrophy of kidney following extra corporeal shock wave lithotripsy of renal calculus in a paraplegic patient with marked spinal curvature.

OBJECTIVES: To discuss a rare complication of extra corporeal shock wave lithotripsy (ESWL) of renal calculus in a paraplegic patient, who had marked curvature of thoracic and lumbar spine. DESIGN: A case report of a paraplegic patient, who developed renal atrophy and hypertension after undergoing ESWL of staghorn calculus. SETTING: Regional Spinal Injuries Centre, Southport and Mersey Regional Lithotripsy Unit, Royal Liverpool University Hospital, Liverpool, UK. PARTICIPANT: A 28-year-old male with spina bifida, paraplegia at L-1 level and considerable curvature of spine and tilting of pelvis. METHOD: ESWL was carried out in three sessions by delivering 1934, 1876, and 2025 shock waves respectively. Localisation of the staghorn calculus was difficult because of spinal curvature and pelvic tilt. RESULTS: A follow-up IVU, performed 3 months after last ESWL treatment, revealed no residual stone in the left kidney, apart from a little low-density calcification in the renal parenchyma adjacent to the lower pole calyx. There were no calculi in the left ureter. The left kidney had become small, though still functioning. MAG-3 isotope renogram showed the left kidney to be markedly atrophic. Relative renal function: right kidney, 94%; and left kidney, 6%. He developed hypertension and a laparoscopic left nephrectomy was performed at another hospital. CONCLUSION: Difficulty in localisation of renal calculi for ESWL must be anticipated in spinal bifida and spinal cord injury patients, who have significant spinal curvature. Because of problems in the positioning of a patient with marked curvature of spine and pelvic tilt, and consequent difficulties in accurate localisation of renal calculi for lithotripsy, these patients may be at increased risk of developing renal parenchymal and vascular damage following ESWL.

Adult↗
PubMed2002

Isolation and characterization of a novel Bacillus strain from coffee phyllosphere showing antifungal activity.

AIMS: The isolation and characterization of a novel coffee-associated Bacillus mojavensis strain, designated as strain AB1, and its survival on the coffee phyllosphere. METHODS AND RESULTS: A pair of 16S rDNA primers was designed to amplify a highly variable region within the 16S rDNA gene of Bacillus spp., with the purpose of identifying the AB1 isolate through PCR and sequence analysis. By this method, AB1 was identified as a strain of B. mojavensis. Bioassays were carried out to characterize the broad spectrum antifungal activity of AB1. Plant colonization studies revealed that AB1 could colonize the coffee phyllosphere better than Bacillus thuringiensis. CONCLUSIONS: These studies suggest that AB1 could be a new strain of B. mojavensis. AB1 is also shown to have antifungal activity against a wide spectrum of pathogenic fungi. The antifungal metabolite of AB1 has been partially characterized as a thermostable, protease- and alkali-resistant substance that is secreted into the surrounding medium. SIGNIFICANCE AND IMPACT OF THE STUDY: As far as is known, this is the first strain of B. mojavensis which has been identified as inhabiting the coffee phyllosphere. The study highlights the potential use of AB1 as an antifungal agent in the coffee crop and as a delivery agent of the insecticidal toxin of B. thuringiensis to the coffee phyllosphere. The 16S rRNA identification strategy discussed could also be used in the identification of other new Bacillus strains.

Animals↗
PubMed2002

In vitro studies on the effects of herbicides on the growth of rhizobia.

AIMS: To study the possible adverse effect of herbicides on nodulation and nitrogen fixation in legumes by affecting the nitrogen-fixing rhizobia. METHODS AND RESULTS: Experiments were conducted to study the effect of four herbicides (terbutryn/terbuthylazine, trietazine/simazine, prometryn and bentazone) on the growth of nitrogen-fixing pea rhizobia (Rhizobium leguminosarum) in vitro by measuring optical density. Terbutryn/terbuthylazine, trietazine/simazine and prometryn had an adverse effect on the growth of rhizobia whereas bentazone was safe to rhizobia. CONCLUSIONS: The above herbicides could be used in pea at the recommended rates. SIGNIFICANCE AND IMPACT OF THE STUDY: The adverse effects of herbicides on rhizobia were observed at concentrations not normally expected to occur under field conditions. Further, previously observed adverse effects of these herbicides on nodulation and nitrogen fixation of peas were, possibly, not due to their effects in rhizobia but to their adverse effects on the plant growth itself.

Culture Media↗
PubMed2002

Utility and accuracy of template-directed dye-terminator incorporation with fluorescence-polarization detection for genotyping single nucleotide polymorphisms.

There are little independent data available about how well single nucleotide polymorphism (SNP) genotyping technologies perform in the typical molecular genetics laboratory. We evaluated the utility and accuracy of a widely used technology, template-directed dye-terminator incorporation with fluorescence-polarization detection (FP-TDI), in a sample of 177 SNPs selected solely on the basis of map location. Genotypes were generated without optimization using standard protocols. Overall, 81% of the SNPs we studied generated readable genotypes by FP-TDI. Thirty-two SNPs were genotyped in duplicate by PCR-RFLP orfluorescent dye-terminator sequencing. Out of a total of 631 duplicate genotypes, no true discrepancies were detected. The true error rate has a 95% chance of lying between 0 and 6 out of 1000 genotypes. We also tested for deviations from Hardy-Weinberg Equilibrium in 33 SNPs genotyped in 50 unrelated individuals, and no significant deviations were detected. Our FP-TDI data were readily adaptable to automated genotype calling using our own method of cluster analysis, which assigns a probability score to each genotype call. We conclude that FP-TDI is both efficient and accurate. The method can easily fill the needs of SNP genotyping projects at the scale typically used for regional or candidate-gene association studies.

Fluorescence Polarization↗
PubMed2002

Lymphatics in leprosy: relationship to elastic fibres and observations following intra-lesional injections of colloidal carbon.

An investigation of skin lymphatics in leprosy has been undertaken. Examination of 62 skin biopsies from 31 patients with various classifications of leprosy has revealed dilated initial lymphatics within granulomas of lepromatous leprosy, but no significant abnormalities in non-lepromatous disease or in non-granulomatous skin. Colloidal carbon injected intra-lesionally failed to appear within granulomas, but could be seen in lymphatics in non-granulomatous dermis. Elastic fibres were also absent within granulomas. AFB were clearly identified within endothelial cells of initial lymphatics. We suggest lymphatic malfunction may be compartmental, existing only within the granulomas and not in the surrounding normal appearing dermis.

Carbon↗
PubMed2001

Unpredicted spontaneous extrusion of a renal calculus in an adult male with spina bifida and paraplegia: report of a misdiagnosis. Measures to be taken to reduce urological errors in spinal cord injury patients.

BACKGROUND: A delay in diagnosis or a misdiagnosis may occur in patients with spinal cord injury (SCI) or spinal bifida as typical symptoms of a clinical condition may be absent because of their neurological impairment. CASE PRESENTATION: A 29-year old male, who was born with spina bifida and hydrocephalus, became unwell and developed a swelling and large red mark in his left loin eighteen months ago. Pyonephrosis or perinephric abscess was suspected. X-ray of the abdomen showed left-sided staghorn calculus. Since ultrasound scan showed no features of pyonephrosis or perinephric abscess, he was prescribed a prolonged course of antibiotics for infection presumed to arise from the site of metal implant in spine. He developed a discharging sinus, following which the loin swelling and red mark subsided. About three months ago, he again developed a red mark and minimal swelling in the left loin. Ultrasound scan detected no abnormality in the renal or perinephric region. Therefore, the red mark and swelling were attributed to pressure from the backrest of his chair. Five weeks later, the swelling in the left loin burst open and a large stone was extruded spontaneously. An X-ray of the abdomen showed that he had extruded the central portion of the staghorn calculus from left kidney. With hindsight, the extruded renal calculus could be seen lying in the subcutaneous tissue of left loin lateral to the 10th rib in the X-ray of abdomen, which was taken when he presented with red mark and minimal swelling. CONCLUSION: This case illustrates how mistakes in diagnosis could occur in spinal cord injury patients, and highlights the need for corrective measures to reduce urological errors in these patients. Voluntary reporting of urological errors is recommended to facilitate learning from our mistakes. In the patients who have marked spinal curvature, ultrasonography of kidneys and perinephric region may not be entirely reliable. As clinical symptoms and signs may be non-specific in SCI patients, they require prompt, detailed and occasionally, repeated investigations. A joint team approach by health professionals belonging to various medical disciplines, which is strengthened by frequent, informal and honest discussions of a patient's clinical condition, is likely to reduce urological errors in SCI patients.

Adult↗
PubMed2001

Induction of Hsp60 by Photofrin-mediated photodynamic therapy.

Photodynamic therapy (PDT) invokes a number of cellular responses. Other studies have shown that PDT induces transcription and translation of heat shock proteins (Hsps). The expression of mitochondrial heat shock protein, Hsp60, was measured following in vitro Photofrin-mediated PDT in the colon cancer cell line HT29 and its PDT-induced resistant variant HT29-P14 as well as the radiation-induced fibrosarcoma cells RIF-1 and its PDT-induced resistant variant, RIF-8A. Basal levels of Hsp60 were found to be similar in the two murine cell lines. In the human model, the resistant HT29-P14 cell line showed a small increase in basal levels relative to its parental population. Incubation with Photofrin (PII) alone or photosensitization caused a significant increase in Hsp60 levels in all cell lines as determined by flow cytometry. A dose-dependent and temporal relationship for PDT response was observed, maximum levels were detected 6-8 h post PDT, at which time, Hsp60 induction was found to be significantly greater in the two resistant variants. Induction in the RIF cells was also found to be greater after incubation with PII alone at the highest doses tested. These results indicate that the presence of PII and the subsequent oxidative stress of PDT can induce Hsp60 and implicated it as a common factor that may contribute to the resistance observed in the induced resistant cells.

Animals↗
PubMed2001

Mitochondrial contributions to cancer cell physiology: potential for drug development.

Mitochondria make an integral contribution to the regulation of several aspects of cell biology such as energy production, molecular metabolism, redox status, calcium signalling and programmed cell death. In accordance with an endosymbiotic origin, mitochondria rely upon the nucleus for synthesis and function. In addition, these organelles can respond to intra- and extracellular cues independently, and there exists a highly coordinated "cross talk" between mitochondrial and nuclear signals that can greatly influence cell behaviour. This review focuses upon the putative roles of altered mitochondrial physiology in the process of cellular transformation. Discussed are: mitochondria as targets of drug-induced cytotoxicity or cancer promotion, as regulators of apoptosis, as sources of cell signalling through reactive oxygen species, and mitochondrial control of specific nuclear responses.

Animals↗