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Biomedical subjects

P Kumar

Publications and source records attributed to P Kumar.

At least 145 records · Page 8Linked to original sources
PubMed2000

Posttransplantation lymphoproliferative disorder of the head and neck: imaging features in seven adults.

PURPOSE: To determine the cross-sectional imaging findings of posttransplantation lymphoproliferative disorder (PTLD) of the head and neck. MATERIALS AND METHODS: Computed tomographic (CT) scans (n = 6) and magnetic resonance (MR) images (n = 2) in seven patients with histopathologically proved PTLD of the Waldeyer (lymphoid) ring or cervical lymph nodes were retrospectively reviewed for abnormalities. RESULTS: The interval between transplantation and PTLD onset was 3.5-108 months (mean, 30 months). All patients had imaging abnormalities involving the Waldeyer ring, and focal 2.0-4. 5-cm masses were present in six patients (unilateral oropharyngeal tonsil in two, bilateral oropharyngeal tonsils in one, nasopharyngeal adenoids in three, unilateral pharyngeal tonsil and ipsilateral nasopharynx in one). In three patients, the mass was centrally low attenuating at CT or isointense to fluid at MR imaging, with enhancing solid peripheral lymphoid tissue. Three patients also had nodal findings: one with a 7-cm low-attenuating nodal mass in the right neck and two with numerous bilateral lymph nodes (mostly normal sized) in the anterior and posterior cervical lymph chains. One patient also had a small mass in the upper mediastinum. CONCLUSION: In the setting of organ transplantation, findings of masses in the Waldeyer ring or an excessive number of cervical nodes should increase the index of suspicion of PTLD.

Adenoids↗
PubMed2000

Serial measurement of vascular endothelial growth factor and transforming growth factor-beta1 in serum of patients with acute ischemic stroke.

BACKGROUND AND PURPOSE: Both vascular endothelial growth factor (VEGF) and transforming growth factor-beta1 (TGF-beta1) are expressed in higher than normal concentrations in the penumbra of patients after ischemic stroke. Because both cytokines are central to the processes of angiogenesis, tissue inflammation, and fibrosis, we performed serial measurements of these cytokines in patients with cerebral infarction and determined their relationship to stroke etiology and volume. METHODS: We serially (at days 0, 1, 3, 7, and 14) measured the serum levels of VEGF and active TGF-beta1 in 29 patients with acute ischemic stroke. Age-matched healthy subjects (n=26) were used as controls. RESULTS: Expression of VEGF was significantly increased in the majority of patients after acute stroke at each of the time points compared with normal controls. Highest expression occurred at day 7 (588+/-121 pg/mL; P=0.005), and it remained significantly elevated at 14 days after stroke. Expression of VEGF correlated with infarct volume, clinical disability (Scandinavian Stroke Scale), and peripheral leukocytosis and was significantly higher in patients with atherothrombotic large-vessel disease and ischemic heart disease (P<0.05 in all cases). In contrast, expression of active TGF-beta1 was not significantly different from control patients at any of the measured time points. When the mean concentration of TGF-beta1 from each patient (pooled time points) was compared with the control mean, a significant increase was found in only 2 patients, whereas levels decreased in 12 patients (P<0.05). There was no correlation between circulating active TGF-beta1 and VEGF expression, leukocytosis, stroke subtype, or patient disability as assessed by Scandinavian Stroke Scale score. CONCLUSIONS: VEGF but not TGF-beta1 showed a dramatic increase in serum of stroke patients. Correlation between stroke severity and VEGF concentration suggests it could be involved in the subsequent repair processes resulting in partial recovery after stroke. Correlation between VEGF expression and peripheral leukocytosis suggests that these changes may also reflect the immunologic status of the patient. VEGF may play an important role in the pathophysiology of acute ischemic stroke and could be of value in future treatment strategies.

Acute Disease↗
PubMed2000

Steroidogenic alterations in testes and sera of rats exposed to trichloroethylene (TCE) by inhalation.

1. Trichloroethylene (TCE) is an organic unsaturated solvent used in dry cleaning, metal degreasing, thinner for paints/varnishes, anaesthetic agents etc. Human beings are considerably exposed to TCE vapours by inhalation route. 2. TCE has been reported to induce spontaneous abortions and congenital cardiac malformation in occupationally exposed women. However, scanty on-line information is available regarding toxic effects of TCE on male reproductive efficiency in experimental animals. 3. Our earlier observations with TCE inhalation in male rats (376 p.p.m., 4 h/day, 5 days a week) for 12 and 24 weeks using whole body dynamic inhalation chamber consistently showed significant decrease (P<0.05) in total epididymal sperm count and sperm motility. The mating experiments of above TCE inhaled rats with virgin unexposed females showed significantly decreased fertility. 4. These observations prompted us to investigate whether or not primary testicular steroidal precursors (cholesterol and ascorbic acid) and testosterone have any role in TCE induced significantly decreased epididymal sperm count, sperm motility and overall male reproductive inefficiency resulting therefrom. 5. The results indicate significant decrease (P<0.05) in total epididymal sperm count, sperm motility, specific activities of enzymes Glucose 6-p dehydrogenase (G6PDH) and 17 beta hydroxy steroid dehydrogenase (17betaHSD) with concomitant decrease in serum testosterone concentrations in TCE inhaled rats showing reduced male reproductive efficiency. There was net accumulation in total cholesterol contents in testes of TCE exposed rats. 6. The findings in the present study indicate possible impairment of testosterone biosynthesis in TCE inhaled rats after 12 and 24 weeks. These findings also serve in parts to elucidate the mechanism of reproductive inefficiency in TCE exposed rats. The role of testosterone in this phenomenon is being reported for the first time.

17-Hydroxysteroid Dehydrogenases↗
PubMed2000

Development of artificial articular cartilage.

Attempts have been made to develop an artificial articular cartilage on the basis of a new viewpoint of joint biomechanics in which the lubrication and load-bearing mechanisms of natural and artificial joints are compared. Polyvinyl alcohol hydrogel (PVA-H), 'a rubber-like gel', was investigated as an artificial articular cartilage and the mechanical properties of this gel were improved through a new synthetic process. In this article the biocompatibility and various mechanical properties of the new improved PVA-H is reported from the perspective of its usefulness as an artificial articular cartilage. As regards lubrication, the changes in thickness and fluid pressure of the gap formed between a glass plate and the specimen under loading were measured and it was found that PVA-H had a thicker fluid film under higher pressures than polyethylene (PE) did. The momentary stress transmitted through the specimen revealed that PVA-H had a lower peak stress and a longer duration of sustained stress than PE, suggesting a better damping effect. The wear factor of PVA-H was approximately five times that of PE. Histological studies of the articular cartilage and synovial membranes around PVA-H implanted for 8-52 weeks showed neither inflammation nor degenerative changes. The artificial articular cartilage made from PVA-H could be attached to the underlying bone using a composite osteochondral device made from titanium fibre mesh. In the second phase of this work, the damage to the tibial articular surface after replacement of the femoral surface in dogs was studied. Pairs of implants made of alumina, titanium or PVA-H on titanium fibre mesh were inserted into the femoral condyles. The two hard materials caused marked pathological changes in the articular cartilage and menisci, but the hydrogel composite replacement caused minimal damage. The composite osteochondral device became rapidly attached to host bone by ingrowth into the supporting mesh. The clinical implications of the possible use of this material in articular resurfacing and joint replacement are discussed.

Aluminum Oxide↗
PubMed2000

Impact of anemia in patients with head and neck cancer.

Head and neck squamous cell carcinoma, which is comprised of a heterogeneous group of tumors arising from the epithelial lining of the oral cavity, pharynx, and larynx, is a locoregional disease. Tumor hypoxia and anemia are known to adversely effect the efficacy of radiation therapy, a local treatment modality. Therefore, head and neck cancers represent an ideal model for assessing the impact of anemia following treatment with radiation therapy. Various treatment strategies aimed at increasing tumor oxygenation in head and neck cancer patients (including hyperbaric oxygen and hypoxic cell radiosensitizers) have been studied. These studies have been fueled by evidence that hypoxia adversely effects the radiosensitivity of cells. Although the exact mechanism of action of the oxygen effect is not known, in vitro studies with conventional photon radiation therapy under normoxic conditions have shown an effectiveness of 2.5-3.0 times greater than that achieved under anoxic conditions. Recent studies, including large retrospective analyses, have demonstrated the dramatic adverse impact of anemia upon locoregional tumor control and survival. These studies, which have revealed hemoglobin levels as a powerful prognostic factor, provide compelling evidence for the value of reversing anemia and hence tumor hypoxia in head and neck cancer patients.

Anemia↗
PubMed2000

Neonatal autopsies: a 10-year experience.

OBJECTIVES: To identify trends in neonatal autopsy rates at a tertiary care hospital during the last decade, to determine the concordance between antemortem and post-mortem diagnoses, and to describe patient characteristics that influenced diagnostic yield on autopsy. DESIGN: Retrospective review of medical records. SETTING: Tertiary care children's hospital. PATIENTS: All neonatal deaths between January 1, 1984, and December 31, 1993. MAIN OUTCOME MEASURES: For those with autopsies, data included length of stay, diagnostic imaging studies, antemortem diagnoses, and autopsy findings. Autopsy diagnoses were compared with antemortem findings and classified according to concordance. RESULTS: Of 487 neonatal deaths, autopsies were performed in 296 (61%). The autopsy rate declined significantly during 10 years from 71.2% (1984-1988) to 47.7% (1989-1993). New diagnoses were made at autopsy in 44% of cases. Major discordancies were identified in 35 infants (12%); minor discordancies in 95 (32%). Autopsies were more likely to reveal new diagnoses in infants born at 28 to 36 weeks' gestation and in those whose mothers had no prenatal care. Major findings at autopsy were more likely in infants whose mothers had no prenatal care and in infants who died within 6 hours of birth. There was no relationship between new findings at autopsy and age, length of hospital stay, or antemortem imaging studies. CONCLUSIONS: This study reveals a significant decline in neonatal autopsies during a 10-year period. This study also demonstrates that neonatal autopsy continues to provide clinically significant data and remains a valuable tool in perinatal medicine.

Adult↗
PubMed2000

Impact of Anemia in Patients With Head and Neck Cancer.

Head and neck squamous cell carcinoma, which is comprised of a heterogeneous group of tumors arising from the epithelial lining of the oral cavity, pharynx, and larynx, is a locoregional disease. Tumor hypoxia and anemia are known to adversely effect the efficacy of radiation therapy, a local treatment modality. Therefore, head and neck cancers represent an ideal model for assessing the impact of anemia following treatment with radiation therapy. Various treatment strategies aimed at increasing tumor oxygenation in head and neck cancer patients (including hyperbaric oxygen and hypoxic cell radiosensitizers) have been studied. These studies have been fueled by evidence that hypoxia adversely effects the radiosensitivity of cells. Although the exact mechanism of action of the oxygen effect is not known, in vitro studies with conventional photon radiation therapy under normoxic conditions have shown an effectiveness of 2.5-3.0 times greater than that achieved under anoxic conditions. Recent studies, including large retrospective analyses, have demonstrated the dramatic adverse impact of anemia upon locoregional tumor control and survival. These studies, which have revealed hemoglobin levels as a powerful prognostic factor, provide compelling evidence for the value of reversing anemia and hence tumor hypoxia in head and neck cancer patients.

Journal Article↗
PubMed2000

Acute inhalation toxicity study of 2-fluoroacetamide in rats.

One of the most potent rodenticides is 2-fluoroacetamide (2-FA). Toxicity of this chemical is well documented. However, its inhalation toxicity data is not available in the literature. Hence, acute inhalation toxicity study was carried out by exposing male and female rats to aerosols of 2-FA at different concentrations for 4 h in a dynamically operated whole body inhalation exposure chamber. During and after the inhalation exposure the rats were less active, and showed mild tremors and convulsions. At higher concentrations the rats died after 2-3 days. The estimated 4-h LC50 for male and female rats was 136.6 and 144.5 mg.m-3 respectively. Exposure to 0.7 LC50 for 4 h duration showed an increase in the liver weight of male and female rats 7 days after exposure. Various haematological and biochemical variables determined were within the normal limits. However, histological findings showed injured lung as indicated by desquamation and necrosis of the epithelium of the respiratory tract. Marked hypertrophy of hepatocytes displaying strong acidophilic granulated cytoplasm was observed. Focal dilatation of renal proximal tubules in kidney with cytoplasmic vacuolation, and irregularly placed pyknotic nuclei were seen. The present study shows that 2-FA is a highly toxic chemical through the inhalation route based on the LC50 value. Consequently necessary precautions should be taken during its handling.

Animals↗
PubMed2000

Substance abuse by medical students and doctors.

The doctors are vulnerable to substance abuse/addiction due to their ready accessibility to the substances of abuse. There is higher percentage use of alcohol, tranquillisers and psychedelics among medical students, and dependence rates are 5% for medical students and 3% for doctors. Majority of the substance-abusing doctors are graduates, belong to medicine speciality (21%) and majority of them prescribe drugs to themselves (37%). The consultants experience more substance related complications, despite having late age of onset of alcohol and substance dependence, less number of concomitant substance abuse and less career handicap. Stress (situational, personal and professional), medical student abuse and family history of alcoholism are the major risk factors. Despite paucity of studies in Indian population, substance use is reported between 32.5% to as high as 81.2% among medical students, intems and house physicians. In spite of the treatment dilemmas, the physicians do respond favourably to treatment. These findings have implications in planning preventive and interventional strategies for this professional group.

Alcohol-Related Disorders↗
PubMed2000

Acquired immunodeficiency syndrome presenting as testicular tuberculosis.

A 50 year old heterosexual male presented with fever and cough with expectoration of months duration, and swelling in the right testis. The serological tests showed positivity for HIV 1 and 11 antibodies. Testicular biopsy from the right testis showed epitheloid cell granulomas with central caseous necrosis and peripheral mantle of lymphocytes and plasma cells. Zeihl-Neelsen stain on tissue sections showed AFB positivity. To the best of our knowledge this is the second reported case of acquired immunodeficiency syndrome presenting as testicular tuberculosis.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Ovarian strumal carcinoid--report of a case that matastasized.

Ovarian teratomas are known for their ability to form a wide variety of tissues. One unusual example of this potential is the strumal carcinoid in which the thyroid tissue is found in intimate association with carcinoid tumor. Although considered as a malignant transformation of struma ovarii, it is almost always benign. We report a rare case of strumal carcionid in a 44 year old lady who had metastasis in the contralateral ovary, myometrium and lungs.

Adult↗
PubMed2000

Subacute (90 days) oral toxicity studies of Kombucha tea.

Kombucha tea (KT) is a popular health beverage and is used as an alternative therapy. KT is prepared by placing the kombucha culture in solution of tea and sugar and allowing to ferment. The inoculum is a fungus consisting of symbiotic colony of yeast and bacteria. KT is consumed in several countries and is believed to have prophylactic and therapeutic benefits in a wide variety of ailments, viz., intestinal disorders, arthritis, ageing and stimulation of immunological system. Though KT is used in several parts of the world its beneficial effects and adverse effects have not been scientifically evaluated. Since there are no animal toxicological data on KT, subacute oral toxicity study was carried out. Five groups of rats were maintained: (a) control group given tap water orally, (b) KT given 2 ml/kg orally, (c) plain tea (PT) given 2 ml/kg orally, (d) KT given in drinking water, 1% (v/v) and (e) PT given in drinking water, 1% (v/v). The rats were given this treatment daily for a period of 90 days. Weekly records of weight, feed intake, water intake and general behaviour were monitored. There was no significant difference in the growth of the animals as evidenced by the progressive body weight change. The organ to body weight ratio and histological evaluation did not show any toxic signs. The haematological and biochemical variables were within the clinical limits. The study indicates that rats fed KT for 90 days showed no toxic effects.

Administration, Oral↗
PubMed2000

Seropositivity for intracellular bacterial infections among abattoir associated personnels.

Studies were carried out to detect the antibodies against zoonotic intracellular bacterial infections viz., brucellosis, listeriosis and tuberculosis in abattoir associated personnel employing dot-ELISA. Out of 165 serum samples tested 25.5, 40.0 and 10.9 per cent were detected as positive for brucellosis, listeriosis and tuberculosis, respectively. Immunodetection of these occupationally exposed persons for IgM as well as IgG antibodies revealed positivity for IgM, IgG and IgM + IgG in 8.5, 17.6 and 13.9 per cent for listeriosis and 5.5, 2.4 and 3.0 for tuberculosis respectively. Antibodies against brucellosis and listeriosis both were detected in 10.9 per cent persons, while 6.7 per cent persons were positive for both listeriosis and tuberculosis. No person was found positive with both brucellosis and tuberculosis. All the three infections were detected in 3.6 per cent persons.

Abattoirs↗