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Biomedical subjects

G Singh

Publications and source records attributed to G Singh.

At least 217 records · Page 12Linked to original sources
PubMed1999

Reappearing CT lesions: 4 cases.

An overwhelming majority of disappearing CT lesions in India have been aetiologically linked to cysticercosis. We report 4 patients with disappearing CT lesions in whom the lesion later reappeared at the same (3 patients) or different site (1 patient). One patient was a Taenia carrier. Serial MRI evaluation in one patient revealed a persisting lesion in the interval period. The contribution of these observations towards the understanding of the aetiology of disappearing CT lesions is discussed.

Adolescent↗
PubMed1999

Mitochondrial membrane potential regulation is independent of c-fos expression.

Tumour cells contain mitochondria with elevated membrane potentials compared with normal cells, and thus this feature provides a selective target for destroying tumour cells. To improve mitochondrial-based therapies, a better understanding of the factors involved in regulating mitochondria are required. Since v-fos overexpression has been shown to elevate mitochondrial membrane potentials in rat fibroblasts, we investigated whether the human homologue, c-fos, was also capable of regulating the mitochondrial membrane potential in cells. Rat fibroblasts transfected with the c-fos gene did not accumulate more rhodamine 123 (Rh123) nor did they retain this Rh123 for extended periods of time compared with their parental line. Moreover, there was no difference in survival following dequalinium chloride (Deca) treatment between transfectants and controls. Similarly, reduction of c-fos expression in rat fibroblasts did not significantly alter their mitochondrial membrane potential. In addition, human ovarian carcinoma cells, which overexpress the c-fos gene, did not accumulate more Rh123 nor were they hypersensitive to Deca compared with their parental line. In another human ovarian carcinoma cell line, selection of variants with lower mitochondrial membrane potential did not alter c-fos mRNA or protein levels. These data suggest that alterations in c-fos expression do not regulate the magnitude of the mitochondrial membrane potential.

Animals↗
PubMed1999

Role of computed tomography in spinal trauma.

Twenty patients admitted for spinal trauma were studied with computed tomography (CT) scan. All the patients had initial routine plain radiographs in the anteroposterior and lateral views. Ten patients sustained injury due to fall from height, 7 suffered road side accident, 2 had injury due to fall of weight on back and one suffered due to slip on floor. Twelve patients had injury at multiple levels. Twenty-four vertebral bodies were involved in 20 patients, 10 had fracture of posterior elements only. Neurological deficit occurred in 16 patients. CT scan provided more information than plain radiography, which missed vertebral body fracture in 2 out of 24 instances and spinal canal compromise in 7 out of 12 patients. CT scan detected posterior element injuries better and in greater detail in all cases.

Adolescent↗
PubMed1999

Cysticercus immunoblot assay in patients with single, small enhancing lesions and multilesional neurocysticercosis.

A single, small (< 20 mm), ring or disc shaped contrast enhancing lesion located at the cortical-subcortical junction with minimal or no surrounding edema on computed tomography is the commonest mode of presentation of neurocysticercosis in the Indian subcontinent. Serum samples of 37 patients with these single, small enhancing lesions (SSEL's) and five patients with typical multilesional parenchymal neurocysticercosis were tested by the electro-immunoblot transfer (EITB) assay and the enzyme linked immunosorbent assay (ELISA). EITB was positive in 18 patients (48.64%) and ELISA was positive in 21 patients (56.76%) with SSEL's. On the other hand EITB was positive in all five patients (100%) and ELISA was positive in four patients (80%) with multilesional neurocysticercosis. The low sensitivity of the EITB in the SSEL's is probably linked to an insufficient immune stimulation provided by a single cysticercus cyst.

Humans↗
PubMed1999

Utility of HemoCue in estimation of hemoglobin against standard blood cell counter method.

INTRODUCTION: There are various methods which have been recommended for haemoglobin (Hb) estimation for assessment of anaemia. Each method has it's advantages and limitations. OBJECTIVE: The present study was conducted to assess the utility of HemoCue, a recent method, in assessment of haemoglobin against the standard blood cell counter (BCC) method. METHODOLOGY: Eighty five venous blood samples were collected, Hb was assessed in each by utilising the HemoCue and BCC methods. The results were compared utilising the standard statistical methods. RESULTS: The HemoCue provided consistently higher value in comparison to BCC by a margin of 0.5 g/dl. It is known that the correlation coefficient is independent of change of origin but mean gets affected. Therefore, we can subtract 0.5 g/dl from the Hb estimates achieved by HemoCue through which all conditions regarding better agreement between both methods get satisfied. The two assays correlated well. CONCLUSION: The HemoCue method was found more rapid and easy in assessment of total hemoglobin as compared to blood cell counter method with an adjustment of 0.5 per dl.

Anemia, Iron-Deficiency↗
PubMed1999

New observations on carrying angle.

Based on experiments on fresh cadaveric and accidentally amputated 8 upper limbs of children, study of ulnae for presence and absence of non articular strip on the trochlear notch, measurements of carrying angle, length of forearm bones, pronation-supination, height and weight in 2250 infants, children and adults of various age groups and clinical observations on 800 cases of injuries around elbow many new facts have been observed about the development of the carrying angle and its significance in the etiopathogenesis of various types of fractures seen around the elbow. The carrying angle develops in response to pronation of the forearm and is dependent on length of the forearm bones. Lesser the length of forearm bones greater is the carrying angle. So the carrying angle is more in shorter persons as compared to taller persons. It is abduction at the shoulder and not the carrying angle which keeps the swinging upper limbs away from the side of the pelvis during walking. Carrying angle is not a secondary sex character. The type of fracture a child sustains after fall on outstretched hand is also determined by the value of the carrying angle. A new type of fracture hitherto undescribed in the literature, T-Y fracture of the distal humeral epiphysis is also reported.

Adolescent↗
PubMed1999

Ultrastructural changes in the sinuatrial and atrioventricular nodes of the heart of the monkey (Macaca fascicularis) after bilateral vagotomy.

This study describes the ultrastructural changes in the sinu-atrial (SA) and atrio-ventricular (AV) nodes of the monkey (Macaca fascicularis) after bilateral mid-cervical vagotomy at 1, 3, 5, 7 and 14 days post-operations. The changes were similar in both types of nodal cells. The most obvious feature of the degenerating nodal cells was the swollen mitochondria with disrupted cristae. Other changes include increased granular sarcoplasmic reticulum, increased glycogen particles, vacuolation of mitochondria and increased lysosomal activity. Axonal profiles in the vicinity of the nodal cells showed swelling and vacuolation. Cardiac neurons also showed some changes such as distended granular endoplasmic reticulum, increased accumulation of glycogen particles and increased lipofuscin granules. Macrophages and Schwann cells were the main scavengers in removing the degenerated nodal cells and axonal profiles. In the case of affected cardiac neurons, satellite cells seemed to act as main scavenger cells. It is postulated that the nodal cells are dependent on the incoming fibres of the vagus nerve for their survival. By an understanding of the ultrastructural changes in the nodal cells after bilateral vagotomy, it may help in developing new strategies to explore in depth of the conducting system of the heart.

Animals↗
PubMed1999

Ultrastructural study of the effects of 6-hydroxydopamine on the sinuatrial and atrioventricular nodes of the heart of the monkey (Macaca fascicularis).

The present study examined the ultrastructural changes in the sinuatrial and atrioventricular nodes of the heart of the monkey (Macaca fascicularis) after 6-hydroxydopamine (6-OHDA) at survival times of 1, 3, 5, 7 and 14 days. Changes ranged from dissolution of the cytoplasm to amorphous appearance and darkening of the nodal cells. Initially, the ultrastructural changes were quite similar in both sinuatrial (SA) and atrioventricular (AV) nodal cells but in the later stage, especially at fourteen days, affected SA nodal cells showed empty-looking appearance while affected AV nodal cells displayed a darkened appearance. The cardiac neurons also showed ultrastructural changes such as diffuse accumulation of glycogen particles, distended cisternae of the rough endoplasmic reticulum and increased lipofuscin granules. Some of the vacuolated axonal profiles containing large dense-cored vesicles were in close association with the somata of the cardiac neurons. There were also changes in the non-neuronal cells such as darkening and vacuolation of the cells capping the neurons. Macrophages and Schwann cells were activated to engulf the degenerating nodal cells and axonal profiles. The ultrastructural changes in the nodal cells and the cardiac neurons reflect a disturbance in the cell metabolism presumably brought about by the impairment of the sympathetic nervous system.

Adrenergic Agents↗
PubMed1998

Homocysteine-dependent alterations in mitochondrial gene expression, function and structure. Homocysteine and H2O2 act synergistically to enhance mitochondrial damage.

Mitochondrial abnormalities have been identified in hepatocytes of patients with hyperhomocysteinemia and in endothelial cells from the aortas of rats with diet-induced hyperhomocysteinemia. However, the mechanism by which homocysteine affects mitochondria is unknown. In this report, homocysteine-induced expression of the mitochondrial electron transport chain gene, cytochrome c oxidase III/ATPase 6,8 (CO3/ATPase 6,8), was identified in a human megakaryocytic cell line DAMI using mRNA differential display. Steady-state mRNA levels of CO3/ATPase 6,8, as well as other mitochondrial transcripts, were increased in DAMI cells by homocysteine in a concentration- and time-dependent manner. Despite an increase in mitochondrial RNA levels and changes in mitochondrial ultrastructure, no effect on either cell growth or mitochondrial respiration rates was observed in DAMI cells exposed to homocysteine at concentrations up to 1 mM. In contrast, 1 mM homocysteine in the presence of Cu2+, which is known to generate H2O2, significantly decreased mitochondrial RNA levels, caused gross morphological changes in mitochondrial ultrastructure, and inhibited both cell growth and mitochondrial respiration rates. However, precursors of cellular glutathione and preexposure to heat shock blocked the decrease in mitochondrial RNA levels caused by homocysteine and Cu2+. The observations that (i) homocysteine and H2O2, but not H2O2 alone, caused a decrease in mitochondrial RNA levels, (ii) intracellular levels of H2O2 were significantly increased in the presence of homocysteine and Cu2+, and (iii) catalase, but not free radical scavengers, prevented a decrease in mitochondrial RNA levels, provide evidence that homocysteine and H2O2 act synergistically to cause mitochondrial damage. Furthermore, our findings suggest that intracellular glutathione and heat shock proteins play a role in protecting mitochondria against the adverse effects elicited by homocysteine and H2O2.

Animals↗
PubMed1998

Recent considerations in nonsteroidal anti-inflammatory drug gastropathy.

Conservative calculations estimate that approximately 107,000 patients are hospitalized annually for nonsteroidal anti-inflammatory drug (NSAID)-related gastrointestinal (GI) complications and at least 16,500 NSAID-related deaths occur each year among arthritis patients alone. The figures for all NSAID users would be overwhelming, yet the scope of this problem is generally under-appreciated. The Arthritis, Rheumatism, and Aging Medical Information System (ARAMIS) Post-Marketing Surveillance Program (PMS) has prospectively followed patient status and outcomes, drug side effects, and the economic impact of illness for >11,000 arthritis patients at 8 participating institutions in the United States and Canada. Analysis of these data indicates that: (1) osteoarthritis (OA) and rheumatoid arthritis (RA) patients are 2.5-5.5 times more likely than the general population to be hospitalized for NSAID-related GI events; (2) the absolute risk for serious NSAID-related GI toxicity remains constant and the cumulative risk increases over time; (3) there are no reliable warning signals- >80% of patients with serious GI complications had no prior GI symptoms; (4) independent risk factors for serious GI events were age, prednisone use, NSAID dose, disability level, and previous NSAID-induced GI symptoms; and (5) antacids and H2 antagonists do not prevent NSAID-induced gastric ulcers, and high-risk NSAID users who take gastro-protective drugs are more likely to have serious GI complications than patients not taking such medications. Currently, limiting NSAID use is the only way to decrease the risk of NSAID-related GI events. Ongoing ARAMIS research is aimed at developing a simple point-score system for estimating individual risks of developing serious NSAID-related GI complications.

Animals↗
PubMed1998

The importance of electrodiagnostic studies in acute organophosphate poisoning.

Six patients with acute organophosphate pesticide poisoning in whom electrodiagnostic studies influenced or supported specific decisions in management are described. One patient was admitted to hospital with a diagnosis of acute alcoholic intoxication. Electrodiagnostic studies revealed single stimulus induced repetitive responses and decrement-increment responses at 30 and 50 Hz repetitive nerve stimulation, findings that are indicative of a depolarization block due to inactivation of acetylcholinesterase at the motor end-plate. The patient was subsequently treated as a case of acute organophosphate poisoning. The administration of edrophonium (0.1 mg) to another patient with normal neuromuscular transmission studies unmasked the latent electrophysiological abnormalities. Three instances are described in which electrodiagnostic studies were useful in predicting whether pralidoxime administration was likely to be useful and for how long was pralidoxime therapy to be continued. Phrenic nerve conduction study in one patient with impending respiratory failure revealed an unstimulable phrenic nerve. The potential role of phrenic nerve conduction studies and neuromuscular transmission studies in influencing decisions like intubation and mechanical ventilation is discussed.

Acute Disease↗
PubMed1998

Uncommon presentations of neurocysticercosis.

Neurocysticercosis commonly presents with seizures, raised intracranial tension and dementia. The unusual location of the cysts may result in uncommon manifestations mimicking a host of neurological disorders. Ten patients with neurocysticercosis with rare clinical presentations have been described in this series. These include dorsal midbrain syndrome, isolated bilateral ptosis, papillitis, cerebral hemorrhage, painful cervical radiculopathy, progressive swelling of arm, paraplegia due to intramedullary cyst, third ventricular cyst, dystonia and nominal aphasia masquerading as transient ischaemic attacks. The clinical details and possible mechanisms for these rare presentations are discussed.

Adolescent↗
PubMed1998

The Genome Sequence DataBase (GSDB): improving data quality and data access.

In 1997 the primary focus of the Genome Sequence DataBase (GSDB; www. ncgr.org/gsdb ) located at the National Center for Genome Resources was to improve data quality and accessibility. Efforts to increase the quality of data within the database included two major projects; one to identify and remove all vector contamination from sequences in the database and one to create premier sequence sets (including both alignments and discontiguous sequences). Data accessibility was improved during the course of the last year in several ways. First, a graphical database sequence viewer was made available to researchers. Second, an update process was implemented for the web-based query tool, Maestro. Third, a web-based tool, Excerpt, was developed to retrieve selected regions of any sequence in the database. And lastly, a GSDB flatfile that contains annotation unique to GSDB (e.g., sequence analysis and alignment data) was developed. Additionally, the GSDB web site provides a tool for the detection of matrix attachment regions (MARs), which can be used to identify regions of high coding potential. The ultimate goal of this work is to make GSDB a more useful resource for genomic comparison studies and gene level studies by improving data quality and by providing data access capabilities that are consistent with the needs of both types of studies.

Base Sequence↗
PubMed1998

Photodynamic therapy using Photofrin in combination with buthionine sulfoximine (BSO) to treat 9L gliosarcoma in rat brain.

BACKGROUND AND OBJECTIVE: The reactive oxygen mechanisms associated with cell damage after photodynamic therapy (PDT) may be exploited to enhance tumor destruction. Pharmacological reduction of glutathione (GSH), an inhibitor of reactive oxygen species, can be induced by administration of buthionine sulfoximine (BSO). STUDY DESIGN/MATERIALS AND METHODS: BSO was administered in combination with Photofrin as the photosensitizer in order to promote PDT induced cell damage. Photofrin (12.5 mg/kg) or Photofrin with BSO (440 mg/kg) were administered to male Fischer rats (n = 27) containing an intracerebral 9L gliosarcoma or to non tumored rats. Brain tumor or non tumored brain was treated with an optical (632 nm) irradiance of 140 J/cm2. Animals were sacrificed 24 h after PDT and the volume of tissue necrosis was measured. Brain Photofrin concentration was measured in tumor and in non tumor bearing animals administered either Photofrin or Photofrin with BSO. GSH was measured by high pressure liquid chromatography in tumor and homologous non tumor tissue in animals administered BSO or control solution. RESULTS: The volume of tumor necrosis was significantly greater in animals administered Photofrin and BSO than in animals administered only Photofrin. No differences were detected in non tumored tissue damage between groups. No differences in Photofrin concentration were detected in tumored or nontumored animals between animals administered Photofrin and animals administered Photofrin and BSO. BSO administration preferentially and significantly reduced GSH in tumor compared to non tumor tissue. CONCLUSIONS: Our data suggest that BSO administration preferentially augments tumor destruction without compromising non tumored tissue.

Animals↗
PubMed1998

Bilateral accessory renal arteries associated with some anomalies of the ovarian arteries: a case study.

Accessory renal arteries are found frequently--more often on the left side and occurring in as high as 30-35% of cases in some series. These arteries usually enter the upper or lower poles of the kidney. The main clinical significance of such arteries entering the lower pole is that they may obstruct the ureter and lead to hydronephrosis. We report the presence of accessory renal arteries found during routine dissection in an elderly female cadaver. The uniqueness in the variations noted in our cadaver included (1) a dual relationship of the ureters to the accessory renal arteries and (2) both the right and left ovarian arteries originating from their respective accessory arteries. Anomalous renal vessels arise as a result of the complicated development of the kidneys. Similarly, the aberrant origins of both the ovarian arteries observed here could be explained on an embryological basis.

Aged↗
PubMed1998

Alterations in sheep fetal right ventricular tissue with induced hemodynamic pressure overload.

We report on the cellular and molecular effects of acute and chronic hemodynamic overload on the fetal sheep heart. In one fetus of a twin gestation, the pulmonary artery was banded to create a condition of hemodynamic pressure overload in the right ventricle. The effects of this overload on the right ventricle (RV), left ventricle (LV), and intra-ventricular septum (IVS) of the heart were studied and compared to that in a control, unbanded twin fetus. At the cellular level, the histological data showed that both the size of the nuclei and the overall cell size of cardiac myocytes were increased after five days of banding; although, with one hour of banding no effects were detected at the cellular level. Based on prior studies on connexins which showed their involvement in differentiation, remodeling, and response to load we looked at their expression in control and experimental hearts. At the molecular level, changes in expression of connexin isoforms, the main gap junction protein in the heart, were observed after both one hour and five days of banding. Changes were observed in expression of connexins 40, 43, and 45. For connexin 43 there was a significant reduction confined to the right ventricle, in the chronically treated fetus, whereas, connexins 40 and 45 expression decreased after acute overload. These early molecular changes are significant because the "functional syncytium" of the myocardium is established through the gap junction connections. Alterations in connexin isoform expression affect the development, mechanical, and electrophysiological properties of the heart muscle. These changes may contribute to the ultimate result of continued hemodynamic stress on the right ventricle: heart failure.

Animals↗
PubMed1998

Neurophysiological monitoring of pharmacological manipulation in acute organophosphate (OP) poisoning. The effects of pralidoxime, magnesium sulphate and pancuronium.

OBJECTIVES: The neuromuscular transmission failure in acute organophosphate (OP) poisoning occurs because of the irreversible inactivation of the enzyme acetylcholinesterase located in the neuromuscular junction, and is distinguished neuroelectrophysiologically by single electrical stimulus-induced repetitive responses and either a decremental or a decrement-increment response upon high-rate repetitive nerve stimulation (RNS). Understandably, the administration of pharmacological agents with actions at different sites in the neuromuscular junction would alter the neuroelectrophysiological findings in acute OP poisoning. METHODS: The effect of several pharmacological agents including pralidoxime (10 patients), magnesium sulphate (4 patients) and pancuronium (7 patients) on the neuroelectrophysiological abnormalities was studied in 21 patients with acute OP poisoning. RESULTS: Pralidoxime administration produced neurophysiological amelioration in 11 out of 15 occasions. In those cases where it produced a beneficial effect, pralidoxime administration was continued and its neuroelectrophysiological effects were studied daily. The efficacy of pralidoxime administration was demonstrated by neuroelectrophysiological testing for a maximum of 6 days after poisoning. Three types of neuroelectrophysiological responses to pralidoxime were noted: (i) lack of neuroelectrophysiological improvement (two patients); (ii) initial improvement with subsequent lack of improvement (two patients); and (iii) initial improvement with subsequent normalisation of neuromuscular transmission (5 patients). Normalisation of the electrodiagnostic tests and the failure of pralidoxime to ameliorate the neuromuscular transmission abnormalities were neuroelectrophysiological indications for the discontinuation of pralidoxime treatment. The administration of magnesium sulphate (MgSO4.7H2O, 4 g intravenous) resulted in a decrease in the CMAP amplitude, loss of the repetitive response and conversion of the decrement-increment response at high-rate RNS to an incremental response. Repetitive responses and the decremental response at high-rate RNS also disappeared after the administration of pancuronium (0.5 mg intravenous) to 6 patients. However, in one case where pancuronium administration was preceded by pralidoxime, there occurred a dramatic worsening of the neuromuscular transmission defect. CONCLUSIONS: While the administration of all 3 agents-- pralidoxime, magnesium sulphate and pancuronium-- resulted in the reversion of the neuroelectrophysiological defects, only pralidoxime is contended to be therapeutically useful. The therapeutic benefit due to its administration is limited by a short duration of action, and hence it is recommended that it should be administered for a longer period of time under neuroelectrophysiolgical guidance.

Acute Disease↗