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Biomedical subjects

A Arora

Publications and source records attributed to A Arora.

At least 55 records · Page 3Linked to original sources
PubMed2001

Transplacental carcinogenic potential of the carbamate fungicide mancozeb.

We evaluated the effects of mancozeb (Dithane M4-5), a protective carbamate fungicide, on transplacental carcinogenesis in Swiss albino mice. Mancozeb, a polymeric complex of ethylene bis (dithiocarbamate) manganese with zinc salt, is reported to possess carcinogenic and cocarcinogenic activity in various tumor models. In the present study, pregnant Swiss albino mice were administered mancozeb intraperitoneally on the 14th day of gestation. The first filial generation (F1 progeny) was promoted with a well-known tumor promoter 12-o-tetradecanoyl phorbol-13-acetate (TPA). The results revealed a significantly high tumor incidence (72%) in the F1 progeny of the animals initiated with mancozeb or a well known carcinogen 7,12-dimethyl benzanthracene (DMBA) and promoted with TPA in comparison to animals that were either from mothers given only the vehicle (DMSO) and promoted with TPA in F1 progeny or not promoted with TPA in F1 progeny. No significantly higher tumor incidence was observed in any other experimental groups. These results suggest that mancozeb or its metabolites are capable of crossing the placental barrier and can exert DNA damage and tumor initiating consequences in the fetal cells that, after promotion with TPA, get converted into neoplastic cells.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2001

Management of community acquired respiratory infections.

Respiratory tract infections (RTIs) are the most common diagnosis in children visiting outpatient departments in both developing and developed countries. The impact of these infections is enormous in terms of total morbidity and mortality. Management of these infections requires a meticulous evaluation and a comprehensive but rational use of supportive, symptomatic and specific therapy. Antibiotics are widely prescribed for the treatment of community acquired respiratory infections to compensate uncertainties of diagnosis and prognosis; unnecessary anti-microbial drug therapy is expensive and resistance by respiratory pathogens is increasing at an exponential rate at a time when new anti-viral as well as anti-bacterial agents are being introduced into the therapeutic armamentarium. Major dilemmas persist regarding symptomatic therapy and the indications of antimicrobial agents. A comprehensive but brief review along with latest protocols and advancements is the management of community acquired respiratory infections in children in cited.

Adolescent↗
PubMed2001

Reversible posterior leukoencephalopathy syndrome: a report of 2 cases.

Reversible posterior leukoencephalopathy syndrome (RPLE) is an increasingly recognised disorder, most commonly associated with malignant hypertension, toxaemia of pregnancy or the use of immunosuppressive agents. Two cases of RPLE syndrome occurring in the setting of accelerated hypertension and eclampsia are described. Both patients had seizures, altered sensorium and typical findings on neuroimaging. They had complete clinical and radiological recovery. The clinical course, pathophysiology and neuroimaging features of RPLE syndrome are discussed.

Adolescent↗
PubMed2001

Immunization with HIV-1 subtype B gp160-DNA induces specific as well as cross reactive immune responses in mice.

BACKGROUND & OBJECTIVES: HIV-1 gp160 is an important structural protein for the virus cell interaction and virus entry. Therefore, it is regarded as the most important target for HIV-1 vaccine development. In this study we investigated the use of HIV-1 gp160-DNA construct in eliciting specific and cross reactive cell mediated immune response in mice. METHODS: DNA segment encoding env, tat and rev genes of HIV-1 subtype B (strain BRU-2) was amplified and cloned into mammalian expression vector pCI to generate plasmid pCIBRU-TRE. Mice were injected intramuscularly four times at biweekly intervals with 100 micrograms/dose of pCIBRU-TRE in normal saline, and subsequently analysed for anti HIV-envelope (env) immune responses. RESULTS: A low antibody level was detected as determined by ELISA after 4 doses. Subsequent inoculations failed to increase the antibody titres significantly. Spleen cells from the immunized mice were used for the detection of cellular immune response by lymphocyte proliferation assays (LPA), in vitro production of cytokines and cytotoxic T lymphocyte (CTL) assays. T cell response which was seen from the second week onwards, persisted even at the end of 24 wk following the last dose. Similar levels of T cell proliferation were observed on stimulation with either homologous or heterologous peptides. Cytokine studies showed a Th1 type of response. A cross clade MHC class I restricted CTL response was observed against target cells stimulated with either homologous or heterologous HIV antigens. INTERPRETATION & CONCLUSION: This study demonstrated that DNA encoding full length HIV-1 env glycoprotein gp160 induces specific as well as cross reactive cell mediated immune responses in mice. However, the induction of antibody response was poor.

AIDS Vaccines↗
PubMed2000

Refolded outer membrane protein A of Escherichia coli forms ion channels with two conductance states in planar lipid bilayers.

Outer membrane protein A (OmpA), a major structural protein of the outer membrane of Escherichia coli, consists of an N-terminal 8-stranded beta-barrel transmembrane domain and a C-terminal periplasmic domain. OmpA has served as an excellent model for studying the mechanism of insertion, folding, and assembly of constitutive integral membrane proteins in vivo and in vitro. The function of OmpA is currently not well understood. Particularly, the question whether or not OmpA forms an ion channel and/or nonspecific pore for uncharged larger solutes, as some other porins do, has been controversial. We have incorporated detergent-purified OmpA into planar lipid bilayers and studied its permeability to ions by single channel conductance measurements. In 1 M KCl, OmpA formed small (50-80 pS) and large (260-320 pS) channels. These two conductance states were interconvertible, presumably corresponding to two different conformations of OmpA in the membrane. The smaller channels are associated with the N-terminal transmembrane domain, whereas both domains are required to form the larger channels. The two channel activities provide a new functional assay for the refolding in vitro of the two respective domains of OmpA. Wild-type and five single tryptophan mutants of urea-denatured OmpA are shown to refold into functional channels in lipid bilayers.

Bacterial Outer Membrane Proteins↗
PubMed2000

Modulation of liposomal membrane fluidity by flavonoids and isoflavonoids.

The polyphenolic structures of flavonoids and isoflavonoids confer them with the ability to scavenge free radicals and to chelate transition metals, a basis for their potent antioxidant abilities. Another possible contributory mechanism toward their antioxidant activities is their ability to stabilize membranes by decreasing membrane fluidity. In this study, the effects of representative flavonoids, isoflavonoids, and their metabolites on membrane fluidity and their preferential localization in the membrane were investigated using large unilamellar vesicles (LUVs) as the membrane models. These results were compared with those of cholesterol and alpha-tocopherol. Changes in fluorescence anisotropy values for a series of n-(9-anthroyloxy) fatty acid probes (n = 6, 12, 16) upon addition of the test compounds were used to monitor alterations in membrane fluidity at graded depths in lipid bilayer. The results of the study suggest that the flavonoids and isoflavonoids, similar to cholesterol and alpha-tocopherol, partition into the hydrophobic core of the membrane and cause a dramatic decrease in lipid fluidity in this region of the membrane. Localization of flavonoids and isoflavonoids into the membrane interiors and their resulting restrictions on fluidity of membrane components could sterically hinder diffusion of free radicals and thereby decrease the kinetics of free radical reactions.

Chromans↗
PubMed2000

Cubitus varus: problem and solution.

A lateral closing wedge osteotomy was performed in 39 children with cubitus varus deformity resulting from a supracondylar fracture. All had a deformity of 15 degrees or more, with 5 having more than 30 degrees of varus. The osteotomy was fixed by three different methods. In 8 cases the osteotomy was fixed with 2 parallel Kirschner wies (group K). A modified French technique (group TBW) was used in 25 cases and held with a figure-of-8 wire loop tightened over the screw heads. In the last 6 cases the osteotomy was fixed with an external fixator (group EF). The only poor result (i.e. loss of carrying angle of more than 10 degrees and loss of flexion and extension of 20 degrees or more) was in group K due to pin tract infection and loosening of the K-wires. In the TBW group 5 patients lost some degree of correction, and none became infected. In the EF group no patient suffered pin tract infection or loss of correction. Based on our experience and results, we feel that the best age at which to correct cubitus varus deformity was 6-11 years and that the external fixator is a safe, effective and reliable method to fix the osteotomy. We propose this method of fixation as a good alternative method to the modified French technique, especially in cases of severe cubitus varus deformity, where removal of a large wedge can produce a big step at the osteotomy site, increasing the possibility of disengagement of the stainless steel wire from the screw head. In addition, minor postoperative modifications of correction, if required, can also be performed. It also avoids a second operation for implant removal.

Adolescent↗
PubMed2000

Reactions of Genistein with alkylperoxyl radicals.

Antioxidant actions of the soy isoflavone genistein are believed to contribute to its overall chemopreventive activity. However, the mechanisms of its antioxidant reactions remain unknown. The objective of this study was to characterize the reaction products of genistein (5,7,4'-trihydroxyisoflavone) with peroxyl radicals generated by thermolysis of 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). Genistein oxidations with AMVN-derived peroxyl radicals yielded orobol (5,7,3',4'-tetrahydroxyisoflavone), a hydroxylated derivative of genistein, and several stable adducts of 4'-oxogenistein with AMVN-derived radicals. Some of these adducts include novel structures resulting from secondary oxidations of the AMVN-derived moiety. For all the observed oxidation products, the modifications occurred on the B-ring of the molecule. Genistein oxidation product structures provide potentially useful markers of genistein antioxidant chemistry.

Acetonitriles↗
PubMed2000

Hill-Sachs type lesion of the femoral head in a case of hip instability.

A Hill-Sachs lesion of the shoulder is an indicator of shoulder instability. Hip instability is also a well-recognized phenomenon. However, no operative or arthroscopic features have previously been reported that support the diagnosis of hip instability. We present a case report of a Hill-Sachs type lesion of the femoral head in a patient with acetabular dysplasia revealed by arthroscopy of the hip. We suggest that finding a Hill-Sachs type lesion of the femoral head may also be regarded as indicative of joint instability, just as it is in the shoulder.

Adult↗
PubMed2000

Pre-natal ventriculomegaly and hydrocephalus.

Ultrasonic imaging of the human fetal brain has allowed ventriculomegaly and hydrocephalus to be categorized. In this study 40 fetuses with ventriculomegaly and 21 with an Arnold-Chiari malformation and a myelomeningocele had ventriculomegaly that resolved, stabilised or progressed in utero. Within the progressive group were those with hydrocephalus, hydrocephalus being defined as expansion of the cerebral ventricular atria together with disproportionate increase in the head circumference. The prognosis for fetuses with resolving and stable ventriculomegaly was good, reflecting the fact that the ventricular dilatation in these cases was probably caused by delayed parenchymal and cerebrospinal fluid pathway development. Whereas the prognosis for progressive ventriculomegaly was generally poor, suggesting that the causes were likely to have been chromosomal, genetic, an infective agent or a catastrophic event which had an adverse effect on parenchymal development. The causes of hydrocephalus also adversely affected brain development but additional damage was caused by raised intracranial pressure.

Arnold-Chiari Malformation↗
PubMed2000

Rapidly progressive fatal cutaneous T cell lymphoma with a trauma-related presentation.

A case of rapidly progressive cutaneous T cell lymphoma with a trauma-related presentation in a 73-year-old man is reported. Clinically, the patient presented with an ulcerated cutaneous mass at the site of trauma-related hematoma of the leg. The histopathology was that of tumor phase cutaneous T cell lymphoma with involvement of the skin and subcutis. The diagnostic challenge of this clinical presentation and the rapidly progressive course are highlighted.

Aged↗
PubMed2000

Cure in a case of primary hepatic lymphoma.

Primary hepatic lymphoma is rare malignancy. Cures in this disease are uncommon. We report a young male who was diagnosed as a case of primary lymphoma of the liver in 1992. He was treated with chemotherapy only, which included CHOP (Cyclophosphamide, Adriamycin, Vincristine and Prednisolone) - six cycles; and IMVP-16 (Ifosfamide, Methotrexate and Etoposide) -four cycles. The patient is now disease free and alive for more than five years.

Adult↗
PubMed1999

Microsecond motions of the lipids associated with trypsinized Na,K-ATPase membranes. Progressive saturation spin-label electron spin resonance studies.

The microsecond motions of spin-labeled lipids associated with the Na(+)/K(+)-transporting ATP hydrolase (Na,K-ATPase) in native and tryptically shaved membranes from Squalus acanthias have been studied by progressive saturation electron spin resonance (ESR). This includes both the segmental mobility of the lipid chains and the exchange dynamics of the lipids interacting directly with the protein. The lipids at the protein interface display a temperature-dependent chain mobility on the submicrosecond time scale. Exchange of these lipids with those in the bulk bilayer regions of the membrane takes place on the time scale of the nitroxide spin-lattice relaxation, i.e., in the microsecond regime. The off-rates for exchange directly reflect the specificity of ionized fatty acids relative to protonated fatty acids for interaction with the Na,K-ATPase. These essential features of the lipid dynamics at the intramembranous protein surface, namely, a temperature-dependent exchange on the microsecond time scale that reflects the lipid selectivity, are preserved on removing the extramembranous parts of the Na,K-ATPase by extensive trypsinization.

Animals↗
PubMed1999

Oral versus intravenous corticosteroids in children hospitalized with asthma.

BACKGROUND: Previous studies have demonstrated that in the emergency treatment of an asthma exacerbation, corticosteroids used in conjunction with beta-agonists result in lower hospitalization rates for children and adults. Furthermore, orally administered corticosteroids have been found to be effective in the treatment of outpatients with asthma. However, similar data in inpatients is lacking. OBJECTIVE: The purpose of this study was to determine the efficacy of oral prednisone versus intravenous methylprednisolone in equivalent doses for the treatment of an acute asthma exacerbation in hospitalized children. METHODS: We conducted a randomized, double-blind, double-placebo study comparing oral prednisone at 2 mg/kg/dose (maximum 120 mg/dose) twice daily versus intravenous methylprednisolone at 1 mg/kg/dose (maximum 60 mg/dose) four times daily in a group of patients 2 through 18 years of age hospitalized for an acute asthma exacerbation. All patients were assessed by a clinical asthma score 3 times a day. The main study outcome was length of hospitalization; total length of stay and time elapsed before beta-agonists could be administered at 6-hour intervals. Duration of supplemental oxygen administration and peak flow measurements were secondary outcome measures. RESULTS: Sixty-six patients were evaluated. Children in the prednisone group had a mean length of stay of 70 hours compared with 78 hours for the methylprednisolone group (P =.52). Children in the prednisone group were successfully weaned to beta-agonists in 6-hour intervals after 59 hours compared with 68 hours for the methylprednisolone group (P =.47). Patients receiving prednisone required supplemental oxygen for 30 hours compared with 52 hours for the methylprednisolone group (P =.04). CONCLUSION: There was no difference in length of hospital stay between asthmatic patients receiving oral prednisone and those receiving intravenous methylprednisolone. Because hospitalization charges are approximately 10 times greater for intravenous methylprednisolone compared with oral prednisone, the use of oral prednisone to treat inpatients with acute asthma would result in substantial savings.

Administration, Oral↗