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Biomedical subjects

P Mahajan

Publications and source records attributed to P Mahajan.

At least 19 recordsLinked to original sources
PubMed2004

Effect of L-arginine on restraint stress induced modulation of immune responses in rats and mice.

The present study investigates the role of nitric oxide (NO) on restraint stress (RS)-induced modulation of humoral and cell-mediated immune responses in rats and mice. RS produced suppression of humoral immune response, i.e., anti-SRBC antibody titre ( 7.38 +/- 0.32 versus 4.13 +/- 0.30; mean +/- S.E.M., P < 0.001). In case of cell-mediated immunity, in delayed type hypersensitivity (DTH) response the change in paw volume decreased from 0.069 +/- 0.003 mm (mean +/- S.E.M.) in control non-stressed group to 0.038 +/- 0.002 mm in the stressed group (P < 0.001) while percentage leucocyte migration inhibition (% LMI) decreased from 39.7 +/- 1.95 in control non-stressed animals to 15.2 +/- 1.07 in animals subjected to stress (P < 0.01). Pretreating the animals with an NO precursor, L-arginine (1000 mg kg-1, i.p.) antagonized the effect of RS on humoral (anti-SRBC antibody titre 6.50 +/- 0.27 versus 4.13 +/- 0.30, P < 0.001 ) and cell-mediated (DTH response 0.066 +/- 0.002 mm versus 0.038 +/- 0.002 mm, P < 0.001; % LMI 41.5 +/- 1.46 versus 15.2 +/- 1.07, P < 0.01) immune responses. Administration of 7-nitroindazole (7-NI, 50 mg kg-1, i.p.), an inhibitor of neuronal NO synthase, alone further enhanced the immunosuppressive effect of RS (anti-SRBC antibody titre 2.75 +/- 0.25 versus 4.13 +/- 0.30, P < 0.001; DTH response 0.019 +/- 0.002 mm versus 0.038 +/- 0.002 mm, P < 0.001; % LMI 5.0 +/- 1.08 versus 15.2 +/- 1.07, P < 0.01). However, when given before L-arginine treatment, 7-NI reversed the effect of the latter drug on stress-induced immunomodulation (anti-SRBC antibody titre 3.00 +/- 0.27 versus 6.5 +/- 0.27, P < 0.001; DTH response 0.043 +/- 0.003 mm versus 0.066 +/- 0.002 mm, P < 0.001; % LMI 12.0 +/- 0.93 versus 41.5 +/- 1.46, P < 0.01). Unlike its effect on RS-induced immune responsiveness, L-arginine (250, 500, 1000 mg kg-1) when given for 5-7 days to naive non-stressed animals produced dose dependent suppression of both humoral (anti-SRBC antibody titre 6.4 +/- 0.32 versus 5.4 +/- 0.32, 4.0 +/- 0.27, 3.1 +/- 0.30, respectively) and cell-mediated (DTH 0.065 +/- 0.003 mm versus 0.064 +/- 0.004 mm, 0.039 +/- 0.003 mm, 0.020 +/- 0.002 mm, respectively and % LMI 37.52 +/- 1.58 versus 30.48 +/- 1.07, 28.18 +/- 1.22, 19.76 +/- 0.83, respectively) immune responses. 7-NI significantly blocked these immunosuppressive effects of L-arginine (anti-SRBC antibody titre 6.0 +/- 0.38 versus 3.1 +/- 0.030, P < 0.01; DTH response 0.056 +/- 0.004 mm versus 0.020 +/- 0.002 mm, P < 0.001; % LMI 34.76 +/- 1.31 versus 19.76 +/- 0.83, P < 0.01). However, 7-NI when given to non-stressed animals failed to modulate immune responsiveness. Thus, NO appears to play an important role in RS-induced immunomodulation and these effects are different from its effect on immune responsiveness in non-stressed animals.

Animals↗
PubMed2004

Relative values of the interventions of diversion and improved donor-arm disinfection to reduce the bacterial risk from blood transfusion.

BACKGROUND AND OBJECTIVES: The aim of this study was to demonstrate the efficiency of diverting the initial 20-ml donation from the collection bag and of an improved donor-arm disinfection procedure in reducing bacterial contamination in blood. MATERIALS AND METHODS: Donations were collected in bags specially manufactured for the study. These bags incorporated two satellite pouches into each of which 20 ml of blood was collected. Blood initially flowed into sample pouch P1, representing a diversion pouch. Pouch P2 was then filled with 20 ml of blood, which allowed us to sample the collection bag after diversion was complete. Blood then flowed into the standard collection bag. The contents of the pouches were aerobically and anaerobically cultured on the BacT/ALERT automated culture system for 7 days. Two procedures were investigated in the study (each involving 1409 blood donations): one analysed the current disinfection procedure; and the other analysed an improved donor-arm disinfection procedure. RESULTS: The use of diversion alone resulted in a 47% reduction in contamination, and improved donor-arm disinfection alone resulted in a 57% reduction in contamination. Diversion plus improved donor-arm disinfection produced a predicted 77% reduction in contamination. CONCLUSIONS: The study validates diversion and an improved donor-arm disinfection procedure. In combination, these two interventions produced a substantial reduction in contamination. These procedures are to be introduced by the English National Blood Service to enhance the safety of the blood supply.

2-Propanol↗
PubMed2004

Receptor mechanisms involved in the anticonvulsant effect of melatonin in maximal electroshock seizures.

The present study investigates the mechanisms involved in the anticonvulsant effect of melatonin in maximum electroshock (MES) seizures. Melatonin (25-100 mg/kg) dose-dependently decreased the duration of tonic hindlimb extension (THLE). The anticonvulsant effect of melatonin was blocked by bicuculline, a GABA(A) receptor antagonist, and luzindole, an ML(1) receptor antagonist, while prazosin, an ML(2) receptor antagonist, enhanced the anticonvulsant actions of melatonin in this seizure model. Administration of serotonergic agents, mianserin and ondansetron, along with melatonin, increased the antiseizurogenic activity of melatonin, while buspirone had no effect. Pretreating the animals with diazepam, carbamazepine or lamotrigine enhanced the anticonvulsant effect of melatonin. Melatonin thus appears to be an effective anticonvulsant, and melatonin ML(1) receptors, GABAergic and serotonergic mechanisms may play an important role in mediating the anticonvulsant activity of melatonin in electroshock seizures.

Animals↗
PubMed2004

Evaluation of the role of melatonin in formalin-induced pain response in mice.

BACKGROUND: Melatonin, the major secretory product of pineal gland has been suggested to play a regulatory role in the circadian rhythm of body activities including the pain sensitivity. Three subtypes of melatonin receptors, i.e. ML1, ML2 and ML3 have been identified. AIM: To investigate the antinociceptive activity of melatonin and to unravel the underlying receptor mechanisms involved in this action. MATERIAL AND METHODS: Effect of melatonin (25-100 mg/kg, ip) and its interaction with putative melatonin receptor antagonists and opioidergic and serotoninergic agents have been studied in formalin test, a model of tonic continuous pain. Formalin (0.1 ml of 1% solution) was injected under the plantar surface of right hind paw of mice and the time an animal spent in licking the injected paw was measured. STATISTICAL ANALYSIS: The data were analysed by one-way ANOVA followed by Tukey's test for multiple comparisons. RESULTS: Injection of formalin produced two phases of intense licking, an early phase (0-5 min) and a late phase (20-25 min). Melatonin dose-dependently decreased the licking response in both the phases, effect being more marked in the late phase. Luzindole, a ML1 receptor antagonist did not block but rather enhanced the antinociceptive activity of melatonin. However, prazosin, a ML2 receptor antagonist in the low dose (0.5 mg/kg) significantly attenuated but in higher dose (1 mg/kg) enhanced the analgesic effect of melatonin. Naloxone, an opioid receptor antagonist did not reverse but morphine, an opioid agonist enhanced the antinociceptive activity of melatonin. Both mianserin and ondansetron the 5HT2 and 5HT3 receptor antagonists, respectively increased the analgesic effect of melatonin. CONCLUSION: The present results suggest the involvement of ML2 receptors in mediating the antinociceptive activity of melatonin in formalin-induced pain response. Further an interplay between melatonin, alpha-1 adrenergic and 5HT2 and 5HT3 serotoninergic receptors may also be participating in this action.

Animals↗
PubMed2003

Attenuation of the effect of progesterone and 4'-chlordiazepam on stress-induced immune responses by bicuculline.

The present study investigates the effect of progesterone, a pregnane precursor of neurosteroids, and 4'-chlordiazepam (4'-CD), a specific ligand for mitochondrial diazepam binding inhibitor receptor (MDR) involved in neurosteroidogenesis, on restraint stress (RS)-induced modulation of humoral and cell-mediated immune responses. RS produced a significant reduction in anti-sheep red blood cells (SRBC) antibody titre, a measure of humoral immune response, and % leucocyte migration inhibition (LMI) and foot-pad thickness test, measures of cell-mediated immune responses. These effects of RS on immune responses were effectively blocked by pretreating the animals with progesterone (10 mg/kg, sc) or 4'-CD (0.5 mg/kg, sc) administered just before subjecting the animal to RS. The effect of both progesterone and 4'-CD on RS-induced immune modulation was significantly attenuated by bicuculline (2 mg/kg, ip) but not by flumazenil (10 mg/kg, ip). Unlike its effect on RS-induced immune responsiveness, progesterone (5, 10 mg/kg, sc) when administered to non-stressed animals produced a significant suppression of both humoral and cell-mediated immune responses which was not reversed by bicuculline. However, 4'-CD failed to modulate immune response in naive non-stressed animals. These results suggest that progesterone and 4'-CD affect stress-induced immune responses by modulating GABA-ergic mechanism. However, GABA-A receptor system does not appear to be involved in progesterone-induced immunosuppression in nonstressed animals.

Animals↗
PubMed2002

Effect of minocycline and tetracycline on immunological responses in experimental animals.

In recent years, there has been an increase in the use of antibiotics, primarily tetracycline anlogues, like minocy cline to treat rheumatoid arthritis. However, the mechanism of action of these analogues is not clearly defined. The present study investigates the effects of minocycline and tetracycline on some immunological parameters in Wistar rats and Swiss albino mice. Haemagglutination (HA) titre was employed as parameter of humoral immune response and % leukocyte migration inhibition (% LMI) and footpad thickness tests were used as measures of cell mediated immune response. Both minocycline and tetracycline significantly improved humoral immune response in rats as indicated by an increase in anti-SRBC antibody titre. In the LMI test, depending on the time period of drug administration, there was an increase or a decrease in the % LMI. When drugs were administered on days 1-7 after sensitization, both the compounds caused a significant increase in % LMI. However, the % LMI was significantly decreased when the drugs were administered on days 7-13 of sensitization, indicating variable effects of these agents on the Immune mechanism depending on the time of administration in relation to the development of immune responsiveness. Both minocycline as well as tetracycline produced a significant decrease in the paw volume in the footpad-thickness test which indicates a decrease in lymphokine production/release. The present study thus shows that minocycline and tetracycline exhibit immunomodulatory properties, which may contribute significantly to their beneficial effects in rheumatoid arthritis.

Animals↗
PubMed2001

Effect of various antihypertensive drugs on plasma fibrinogen levels in patients with essential hypertension.

In recent years, substantial evidence has accumulated to unambiguously implicate high plasma fibrinogen levels as a major cardiovascular risk factor. An open prospective and randomised pilot study was therefore undertaken in mild to moderate hypertensives to evaluate the effect of various antihypertensive drugs viz enalapril, felodipine and prazosin on the blood pressure and plasma fibrinogen levels. The systolic and diastolic blood pressures were determined at 0, 4 and 8 weeks whereas plasma fibrinogen assays were done at baseline and at the end of the 8th week of treatment in all the drug-treated groups. It was observed that although all the three drugs effectively controlled blood pressure, only enalapril significantly reduced plasma fibrinogen levels. Due to this additional effect, enalapril has potential to control two major cardiovascular risk factors--hypertension and high plasma fibrinogen levels--simultaneously.

Antihypertensive Agents↗
PubMed1999

Effect of whole-body vibration on the low back. A study of tractor-driving farmers in north India.

STUDY DESIGN: A retrospective cohort study of tractor-driving farmers (study group) and non-tractor-driving farmers (control group) matched for age, gender, generic/ethnic group, land-holding, and work routines. OBJECTIVES: To determine, using magnetic resonance imaging and clinical investigations, the effect of whole-body vibrations on the back in tractor-driving farmers. SUMMARY OF BACKGROUND DATA: Low back pain and pathologic changes in the lower backs of tractor drivers have been reported. However, no study with a control group matched for work-related risk factors has been reported. METHODS: Fifty tractor-driving farmers were compared with 50 non-tractor-driving farmers matched for age, gender, ethnic group, land-holding, and work routine. Both groups were interviewed for details of work routine, assets held, family profile, and vibration exposure to assess the influence of these parameters on signs and symptoms of backache. Magnetic resonance imaging was done to assess the effect of exposure on whole-body vibration and degenerative changes in the back. Vibration measurements also were done on tractors to observe the actual severity of the vibrations. RESULTS: Regular work-related backache was more common among tractor-driving farmers (40%) than among non-tractor-driving farmers (18%, P = 0.015). Anthropometric evaluation showed abdominal girth and weight to be significantly higher in tractor-driving farmers (P = 0.006 and 0.046, respectively), whereas while height and arm span were similar between the two groups. Clinical examination for evidence of disc or facet degeneration showed no difference between the two groups. Evaluation of magnetic resonance images of tractor-driving farmers and non-tractor-driving farmers by an orthopedic surgeon, radiologist, and neurosurgeon showed degenerative changes to be similar between the two groups (P > 0.050). CONCLUSIONS: Tractor-driving farmers report backache more often than non-tractor-driving farmers, but no significant objective differences on clinical or magnetic resonance imaging evaluation were found between the two groups.

Adult↗
PubMed1998

Studies on tractor related injuries in northern India.

Epidemiological studies were conducted in two phases each of 1 year duration in nine and 30 villages, respectively, in two northern states of India. Investigations were carried out to determine the causal factors, the activities involved and severity of injuries for farming and non-farming activities in tractor related accidents. A total of 76 cases involving five fatalities and 71 non-fatal injuries were recorded. The pattern of tractor related injuries in India have been found to be very different compared to those reported from highly industrialized countries. Fifty-four percent of tractor related injuries in the first phase and 49% in the second phase were because of non-farming activities. Of the total injuries recorded in both the phases only 1 and 6% were tractor related. A major cause of tractor related injuries were collisions. In the two phases 28 and 40% injured were passengers on tractor or trailer.

Accidents, Traffic↗
PubMed1998

The effect of fluticasone propionate on functional status and sleep in children with asthma and on the quality of life of their parents.

BACKGROUND: Although in the past drug interventions were measured primarily on the basis of their efficacy and safety, today we are increasingly interested in what impact treatments have on the patient's day-to-day activities and quality of life. OBJECTIVES: We sought to assess the effect of treatment with fluticasone propionate (FP) on functional status and sleep disturbances in children with asthma and to evaluate possible changes in the quality of life of the parents of these children after treatment. METHODS: As part of a randomized, double-blind, parallel-group, placebo-controlled, multicenter study on the effects of FP powder (50 or 100 microg twice daily) on growth in children aged 4 to 11 years with mild-to-moderate asthma (n = 325), parents/caregivers completed the following questionnaires at baseline and at weeks 24 and 52 of treatment: Functional Status IIR (FSII), Sleep Scale-Children (SLP-C), and Quality of Life of Parents of Asthmatic Children (QOL-PAC). Change from baseline to weeks 24 and 52 within each treatment group was analyzed by using paired t-tests, and differences between treatment groups were analyzed by using analysis of covariance. RESULTS: Mean FSII and SLP-C scores improved significantly over baseline values with either 50 or 100 microg FP at weeks 24 and 52 (p < 0.05) and were significantly better than scores in the placebo group (p < 0.05). In contrast, FSII scores at week 52 and SLP-C scores at weeks 24 and 52 decreased significantly in the placebo group (p < 0.05). QOL-PAC results revealed that scores on the Burden scale were significantly improved in both FP groups at weeks 24 and 52. Subjective Norms and Social scales improved significantly only in the 100 microg FP group at week 52. CONCLUSIONS: The results of this study show that FP (either 50 or 100 microg twice a day) was associated with significant improvements in functional status and decreased sleep disturbances in children with asthma. In addition, treatment of children with FP was associated with a decreased burden on the parents of these children with asthma.

Administration, Topical↗
PubMed1998

Inhaled fluticasone propionate delivered by means of two different multidose powder inhalers is effective and safe in a large pediatric population with persistent asthma.

BACKGROUND: Inhaled corticosteroids are increasingly being used to treat mild-to-moderate asthma in children. However, data regarding therapy with this class of compounds, especially in children under age 6 years, is limited. Fluticasone propionate is a third generation inhaled corticosteroid with an optimal therapeutic index. Few large prospective clinical trials have been conducted to evaluate the efficacy and safety of fluticasone propionate powder in children. OBJECTIVE: We sought to determine the efficacy and safety of fluticasone propionate powder administered by means of the Diskus and Diskhaler multidose powder inhalers in pediatric patients with persistent asthma. METHODS: Fluticasone propionate powder (50 microg or 100 microg twice daily) or placebo was administered by means of the Diskus or Diskhaler inhalers to 437 children (4 to 11 years old) with persistent asthma for 12 weeks in a randomized, double-blind, parallel-group, multi-center trial. Patients were stratified according to whether they were receiving prior treatment with inhaled corticosteroids or cromolyn or beta2-agonists alone. RESULTS: Fluticasone propionate powder administered by means of Diskus or Diskhaler significantly improved FEV1 (mean increase from baseline of 0.22 to 0.24 L; p < or = 0.023), clinic morning peak expiratory flow (mean increase from baseline of 48 to 55 L/min; p < or = 0.006), patient-measured morning (p < or = 0.001) and evening (p < or = 0.003) peak expiratory flow, and asthma symptom scores (in all but the 50 microg Diskus group; p < or = 0.036), as well as reduced albuterol use (p < or = 0.002) and nighttime awakenings (p < or = 0.019) at endpoint. Efficacy parameters were not significantly different between the two doses with either device. More placebo-treated patients discontinued the study because of lack of efficacy than patients in any fluticasone propionate group (p < 0.001). Fluticasone propionate did not suppress morning plasma cortisol concentrations and did not affect 24-hour urinary free-cortisol excretion. Adverse events were primarily pharmacologic effects of inhaled corticosteroids, and those related to the study drug occurred with low frequency. Patient satisfaction with both the Diskus and Diskhaler devices was high, with a majority of patients (> 80%) rating them favorably. CONCLUSION: This study demonstrated that fluticasone propionate powder, at the conventional recommended doses of up to 200 microg/day administered by means of Diskus or Diskhaler, was well tolerated and improved lung function in children even as young as 4 and 5 years old regardless of whether they were previously treated with inhaled corticosteroids or cromolyn or beta2-agonists alone.

Administration, Inhalation↗
PubMed1997

Impact of fluticasone propionate powder on health-related quality of life in patients with moderate asthma.

Because biological indicators alone do not adequately represent the comprehensive health status of a patient with asthma, we also assessed patients' health-related quality of life (HRQOL) in a randomized, double-blind, placebo-controlled study of the effects of the inhaled corticosteroid fluticasone propionate (FP). A total of 342 patients with moderate asthma were treated twice daily for 12 weeks with FP powder (50, 100, or 250 micrograms) or placebo. At regular intervals, patients completed the Medical Outcomes Study Short Form-36, acute version (SF-36A), a general health status questionnaire measuring eight dimensions of HRQOL; the 20-item Living with Asthma (LWA-20) questionnaire, a disease-specific instrument measuring HRQOL; and three additional questions related to sleep loss and number of nighttime awakenings. Each of the three FP groups compared with placebo had significantly higher scores at study endpoint on the Physical Functioning (p < 0.001) and Role-Physical (p < or = 0.0001) dimensions of the SF-36A; the FP 100- or 250-micrograms groups compared with placebo also had significantly higher scores on General Health Perceptions (p < 0.03), Vitality (p < 0.007), and Mental Health (p < 0.02). At endpoint, all three FP groups compared with placebo had significantly better scores on the LWA questionnaire (p < 0.05) and on the sleep-related items (p < 0.0001). These data, collected using both a general health status questionnaire and an asthma-specific questionnaire, demonstrate that fluticasone propionate powder can improve HRQOL in patients with mild-to-moderate asthma.

Adolescent↗
PubMed1997

Serum and cerebrospinal fluid concentrations of rifampicin at two dose levels in children with tuberculous meningitis.

Twenty patients of tuberculous meningitis (TBM) in age group of 6 months to 10 years included in the study were divided into two groups of 10 patients each. Rifampicin was administered in dosage of 10 mg and 7.5 mg/kg bw to each patient of groups I and II respectively. Drug concentrations in serum and CSF of these patients were measured by a microbiological tube dilution method using a strain of Sarcina lutea. In group I mean serum and CSF concentration was 3.84 micrograms/ml and 0.178 microgram/ml respectively, while in group II it was 2.16 micrograms/ml and 0.206 microgram/ml respectively. These concentrations were many times higher than the MIC against Mycobacterium tuberculosis. Mean percentage penetration of rifampicin in CSF was 5 and 10% in group I and II respectively. We recommend similar studies in large number of children before advocating the therapy with low dose of rifampicin in TBM.

Antibiotics, Antitubercular↗