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Biomedical subjects

M Singh

Publications and source records attributed to M Singh.

At least 199 records · Page 11Linked to original sources
PubMed2001

Long-circulating monensin nanoparticles for the potentiation of immunotoxin and anticancer drugs.

The carboxylic ionophore monensin was formulated into long-circulating nanoparticles with the help of polyethylene glycol/poly (DL-lactide-co-glycolide) diblock copolymers, in an attempt to enhance the cytotoxicity of a ricin-based immunotoxin, anti-My9, and anticancer drugs like adriamycin and tamoxifen. This study looked into various aspects involving the preparation (using a homogenizer and an EmulsiFlex homogenizer-extrusion device) and lyophilization of long-circulating monensin nanoparticles (LMNP) of particle size < 200 nm in diameter. The particle size of LMNP was reduced from 194 nm to 160 nm by passing the nanoparticles through an EmulsiFlex, before freeze-drying. There was a 4.8-83.7% increase in the particle size of LMNP after freeze-drying, which was dependent upon the manufacturing conditions such as use of the EmulsiFlex for size reduction before freeze-drying, the freezing method (rapid/slow) and the concentration of lyoprotectant (mannitol or trehalose) employed for freeze-drying. LMNP freeze-dried with 2.4% of trehalose showed minimal size change (< 9%) after freeze-drying. Further, the freezing method was found to have negligible effect on the particle size of LMNP freeze-dried with trehalose in comparison with mannitol. The entrapment efficiency of monensin in LMNP was found to be 14.2 +/- 0.3%. The LMNP were found to be spherical in shape and smooth in surface texture as observed by atomic force microscopy. In-vitro release of monensin from LMNP in phosphate buffered saline (PBS) pH 7.4 or PBS supplemented with 10% human serum indicated that there was an initial rapid release of about 40% in the first 8 h followed by a fairly slow release (about 20%) in the next 88 h. In-vivo studies conducted with Sprague-Dawley rats showed that 20% of monensin remained in circulation 4-8 h after the intravenous administration of LMNP. An in-vitro dye-based cytotoxicity assay (MTS/PMS method) showed that there was 500 times and 5 times potentiation of the cytotoxicity of anti-My9 immunotoxin by LMNP (5 x 10(-8) M of monensin) in HL-60 sensitive and resistant human tumour cell lines, respectively. Further, LMNP (5 x 10(-8) M of monensin) potentiated the cytotoxicity of adriamycin in MCF 7 and SW 620 cell lines by 100 fold and 10 fold, respectively, and that of tamoxifen by 44 fold in MCF 7 cell line as assessed by crystal violet dye uptake assay. Our results suggest that it is possible to prepare LMNP possessing appropriate particle size (< 200 nm), monensin content and in-vitro and in-vivo release characteristics with the help of a homogenizer and an EmulsiFlex homogenizer-extrusion device. LMNP can be freeze-dried with minimal increase in particle size by using a suitable concentration of a lyoprotectant like trehalose. Furthermore, LMNP could potentiate the cytotoxicity of immunotoxin, adriamycin and tamoxifen by 5-500 fold in-vitro, which will be further investigated in-vivo in a suitable animal model.

Animals↗
PubMed2001

Ovarian hormones elicit phosphorylation of Akt and extracellular-signal regulated kinase in explants of the cerebral cortex.

Estradiol and progesterone both have been demonstrated to afford neuroprotection against various insults. In an attempt to identify potential mechanisms underlying these neuroprotective effects, two key elements within signal transduction pathways linked to neuroprotection were evaluated. In mouse cerebral cortical explants, both estradiol and progesterone elicited the phosphorylation of Akt, a downstream effector of the phosphoinositide-3 (PI-3) kinase pathway. Progesterone also elicited the phosphorylation of extracellular-signal regulated kinase (ERK), a component of the mitogen-activated protein kinase (MAPK) pathway. These effects were not inhibited by the progesterone receptor antagonist, RU486. However, inhibition of either MAPK/ERK kinase with PD98059 or PI-3 kinase with LY294002 successfully inhibited progesterone's actions on ERK and Akt, respectively. Collectively, the data offer novel mechanisms for both progesterone and estrogen action in the central nervous system, demonstrating the functional and mechanistic diversity of gonadal hormones and supporting their neuroprotective potential for such neurodegenerative disorders as Alzheimer disease.

Animals↗
PubMed2001

Peri-abortion contraceptive care: can we reduce the incidence of repeat abortions?

INTRODUCTION: It is of great importance for repeat unwanted pregnancies to be prevented rather than aborted. We therefore sought to: determine the reasons for contraceptive failure in women seeking repeat abortions; audit the peri-abortion contraception services offered at our hospital, and make recommendations regarding peri-abortion contraception services based on the above findings. METHOD: A self-administered questionnaire was used to determine the contraceptive practices and details of peri-abortion contraceptive counselling received by 50 women undergoing a repeat, and 83 women undergoing a first-time, abortion. RESULTS: Ninety-eight percent of women undergoing a repeat abortion reported using contraception at the time of conception, as compared to 83% of women undergoing a first-time abortion. This difference was significant (p = 0.009). Condoms were the main method used by 57% of women undergoing a repeat and 70% of women undergoing a first-time abortion. The oral contraceptive pill (OCP), including both combined oral contraceptive and progestogen-only pill, was the main method used by 37% of women undergoing a repeat and 25% undergoing a first-time abortion. Both these methods were found to be ineffective because of user-dependent failures. All women received peri-abortion contraceptive counselling, but the perceived contents varied. Follow-up contraceptive appointments were made in less than half of women. Although most women chose an optimal contraceptive method as a result of the counselling, compliance with the chosen method in women undergoing repeat abortions was poor. CONCLUSIONS: Standards of audit were met with regards to receipt of contraceptive counselling and agreeing a contraceptive method before discharge. The content of this counselling needs to be improved. The ineffectiveness of the OCP and barrier methods of contraception needs to be highlighted during counselling. Adequate follow-up arrangements need to be provided to ensure compliance of the chosen method of contraception.

Abortion, Habitual↗
PubMed2001

The chemical and biological aspects of fluoroquinolones: reality and dreams.

A vast array of fluoroquinolones having excellent broad-spectrum activity form an invaluable part of the present anti-infective armory of the clinicians. A number of these compounds are today's blockbusters of the antibacterial market due to their therapeutic efficacy having tolerable side effects and thus challenging the predominance of well established beta-lactam antibiotics which are becoming more prone to the resistant pathogenic bacteria. Since the discovery of nalidixic acid the development of fluoroquinolones has experienced an exponential growth and is being continued with more vigor to obtain better drugs having multifunctional action. This article attempts to review the current developments of the chemical and biological aspects of fluoroquinolones in a chronological manner touching upon their antibacterial properties based on the structure activity relationship while pointing out to their mode of action. It also provides an insight into a variety of approaches resulting in elegant manipulations of their basic skeleton and some breakthroughs in their synthetic strategies of a few widely used drugs, which had helped in accelerating their market growth as well as continuing research for newer fluoroquinolones. Since the mode of action of fluoroquinolones being different from beta-lactams and their transportation to the target site is slow several dual action quinolonyl-beta-lactams (Penicillins, Cephalosporins, Penems, Cephems, Carbapenams etc.) have come as a major breakthrough among the hybrid antibiotics. While focusing on the multifunctional activities of such compounds, this review briefly points out to the current trends in various techniques for de novo drug design and development of newer therapeutic molecules, which hold future promises in combating the fight against drug resistant bacteria as it still remains to be won.

Anti-Infective Agents↗
PubMed2001

Randomized comparison of a dry powder inhaler and metered dose inhaler with spacer in management of children with asthma.

OBJECTIVE: Comparison of the clinical efficacy of a transparent, DPI (transparent Rotahaler) with MDI and spacers in childhood asthma. DESIGN: Open, randomized, crossover trial. SETTINGS: Out patient clinic of a referral pediatric center. METHODS: Thirty (mean 6.1 +/-2.7 years) children with moderate persistent asthma were randomized to receive long-term medications by a DPI or a metered dose inhaler with spacer for six weeks and then crossed over to receive the same drugs for another period of six weeks after an initial run in period of one week for training in inhalation techniques. The preventative therapy consisted of inhaled Beclomethasone dipropionate (600 mcg/day) and Salbutamol as per requirement. The patients were monitored by a symptom diary, weekly PEFR, and PEFR variability by the parental record of PEFR measurements at home with Mini Wright s Peakflow meter in accordance with the Consensus guidelines. RESULTS: Comparisons made on weekly symptom scores, PEFR at interval visits, PEFR variability, additional beta sympathomimetic use and acute exacerbations of asthma did not reveal any statistically significant differences during the two treatment periods (>0.05). CONCLUSION: Metered dose inhaler and dry powder inhaler have equal efficacy in anti-inflammatory therapy of bronchial asthma in children.

Anti-Asthmatic Agents↗
PubMed2001

Impact of education and training on neonatal resuscitation practices in 14 teaching hospitals in India.

The impact of a neonatal resuscitation programme (NRP) on the incidence, management and outcome of birth asphyxia was evaluated in 14 teaching hospitals in India. Two faculty members from each institution attended a neonatal resuscitation certification course and afterwards trained staff in their respective hospitals. Each institution provided 3 months pre-intervention and 12 months post-intervention data. Introduction of the NRP significantly increased awareness and documentation of birth asphyxia, as judged by an increased incidence of asphyxia based on apnoea or gasping at 1 and 5 minutes (p < 0.001 and < 0.01, respectively). A significant shift towards more rational resuscitation practices was indicated by a decline in the use of chest compression and medication (p < 0.001 for each), and an increase in the use of bag and mask ventilation (p < 0.001). Although overall neonatal mortality did not decrease, asphyxia-related deaths declined significantly (p < 0.01).

Chi-Square Distribution↗
PubMed2001

Apolipoprotein E polymorphism in India: high APOE*E3 allele frequency in Ramgarhia of Punjab.

High resolution two dimensional gel electrophoresis with the combination of isoelectric focusing (IEF) and density gradient sodium dodecyl-polyacrylamide gel electrophoresis (DG-PAGE) have been employed to investigate the distribution of APOE in Ramgarhia (n = 80) and Ramdasia (n = 70) of Punjab, India. Three alleles APOE*E2, APOE*E3 and APOE*E4 were observed in Ramgarhia and Ramdasia with the frequencies of 0.031, 0.913, 0.056 and 0.043, 0.886 and 0.071, respectively. Higher heterozygosity (20.8%) in Ramdasia reflects greater variation at the APOE locus. The APOE*E3 allele is found to be the highest (0.913) in Ramgarhia in comparison to forty-one populations of the world. A decreasing cline from south to north was evident for *E2 and *E4 allele frequencies (y = -0.002x + 0.141, r = 0.78 and y = -0.004x + 0.229, r = 0.83, respectively, and an increasing cline for the *E3 allele towards north was observed (y = 0.006x + 0.629, r = 0.82) in Asia.

Adult↗
PubMed2001

Role of garlic (Allium sativum L.) in human and plant diseases.

A resurgence of interest in garlic due to recent revelations of its beneficial effects in the treatment of various human and plant diseases and also due to validation of claims made in traditional systems of medicine has resulted a plethora of publications on different aspects of garlic in recent years. Chemical constituents of garlic and their variations on the methods of isolation have been discussed in the present review. Effect of garlic and its constituents against various human and plant pathogenic and saprophytic microorganisms has also been reviewed.

Animals↗
PubMed2001

Influence of influenza viral infection on airway smooth muscle activity.

The contractility of airway smooth muscle (ASM) plays an important role in pathophysiology of several bronchial disorders. Increased contraction of ASM during asthma and respiratory viral infection has been attributed to the release of mediators acting through different receptors. In the present study, influence of influenza type A virus (H1N1) infection has been examined on ASM responsiveness to various bronchoactive agents e.g. adenosine, histamine, 5-hydroxytryptamine (5-HT) and isoproterenol in an organ bath set up for isolated tissue preparation. The contractile effect of adenosine, histamine and 5-HT was enhanced, however, relaxant response of isoproterenol was attenuated with the duration following viral exposure. The most prominent response was observed 48 to 72 hr after infection and tissues from multiple exposure to virus infected animals showed the maximum contractile response. Results demonstrated the deleterious effect of viral infection on ASM function and the findings will be helpful in understanding the mechanism of influenza virus induced bronchoconstriction.

Adenosine↗
PubMed2001

Effect of single prenatal haloperidol exposure on hippocampus and striatum of developing rat brain.

Poor development and differentiation of three layered cytoarchitectural pattern of brain, degenerating pyramidal cells with pyknotic nuclei and substantial loss of both large and small pyramidal cells of the hippocampal CA1 region were observed in fetuses of pregnant Charles-Foster rats exposed to single high dose of haloperidol (50 mg/kg body weight) on day 12 of gestation. In treated striatum, reduction in size, complete degeneration of multipolar cells with fragmented nuclei and increased extracellular spaces were observed. Unsacrificed group of day 12 haloperidol treated rat offsprings at 9 weeks of age exhibited cognitive behavioural dysfunctions in passive avoidance (behaviour) test. These findings indicate that a single (high dose) prenatal haloperidol exposure during critical period of CNS development not only induces micromorphological aberrations in foetal hippocampus and striatum but also lasting cognitive impairment in adult rat offsprings.

Animals↗
PubMed2001

Anatomy of the first septal perforating artery: a study with implications for ablation therapy for hypertrophic cardiomyopathy.

OBJECTIVE: To determine the variability in the size and distribution of the first septal perforating artery (FSPA). MATERIAL AND METHODS: In this pilot study, 10 fresh autopsy hearts from patients who did not have hypertrophic cardiomyopathy (HCM) or clinical evidence of coronary artery disease were evaluated for the variability in the size of the FSPA. The size of the FSPA was also measured during coronary angiography in 8 patients with HCM who were undergoing alcohol septal ablation. RESULTS: Of the 10 autopsy hearts, 2 had a large FSPA (> or = 1.0 mm in maximal diameter) with prominent septal myocardial distribution, 2 had a medium-sized FSPA (0.5-0.9 mm), 2 had a small FSPA (0.1-0.4 mm), 3 had a tiny FSPA (< 0.1 mm), and 1 had an indiscernible ostium. In 2 patients the FSPA supplied the right ventricular free wall. In 4 patients the basal ventricular septum was incompletely supplied by the FSPA. Of the 8 patients with HCM, the FSPA was larger than 2 mm in diameter in 2 patients, 1 to 2 mm in 4, and smaller than 1 mm in 2. The distance between the left anterior descending coronary artery ostium and the origin of the FSPA ranged between 13.1 and 37.4 mm, indicating a large variation in the size and distribution of the FSPA. CONCLUSIONS: Variability in the size and distribution of the FSPA in patients without HCM was substantial. Areas of the heart other than the basal septum were supplied in some patients by the FSPA. In other patients the FSPA did not supply the entire basal septum. Similar findings were noted in patients with HCM. A detailed evaluation of the distribution of the FSPA may be necessary in all patients with HCM who are undergoing alcohol septal ablation.

Adult↗
PubMed2001

Mycobacterium fortuitum wound infection following laparoscopy.

During a six week period in 1999, seven patients who underwent laparoscopic tubectomies at small town health centres near Chandigarh developed chronic discharging sinuses at the site of incision. Mycobacterium fortuitum was isolated from wound discharge of the five patients by standard methods and two patients were smear positive. Environmental samples e.g., tap water, and a variety of fluids did not yield any mycobacteria and swabs from different parts of the laparoscope were sterile. All patients responded to ciprofloxacin and amikacin therapy. Our observation demonstrates that M. fortuitum is a clinically important nosocomial pathogen in setting of surgical wound infection in our country.

Amikacin↗