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Biomedical subjects

N Anand

Publications and source records attributed to N Anand.

At least 55 records · Page 3Linked to original sources
PubMed1994

Unconventional pedicle spinal instrumentation. The Bombay experience.

STUDY DESIGN: A retrospective study of all patients who underwent spinal fusion between 1986 to 1989 with inexpensive, locally made unconventional pedicle spinal instrumentation systems was undertaken. Implants were made with passivated 316L stainless steel, and a single level of instrumentation cost +f430. OBJECTIVES: To demonstrate that simple, cheap pedicle instrumentation systems are as effective as the conventionally available expensive systems, provided proper anterior column support is maintained. METHODS: Ninety out of 102 patients were available for review. Average follow-up was 41 months (range, 22 to 60 months). Implant failures, screw placement, fusion rates, infection, neurologic deficit due to the implant, patient satisfaction, and the benefit of anterior column grafting with the unconventional pedicle spinal instrumentation systems in the long term were evaluated. RESULTS: Forty-four out of 467 screws failed (9%) in 16 patients, seven of whom were symptomatic. There were no plate failures. On comparing burst fractures with (n = 12) and without (n = 10) anterior column grafting, the latter group had a significant increase in implant failures, loss of sagittal alignment, and the time required to fusion. Overall, fusion occurred within 6.5 months. CONCLUSIONS: Anterior column reconstruction in anterior column deficient spines will re-create the normal biomechanics and significantly reduce the incidence of implant failures and loss of sagittal alignment with these systems. Pedicle screw failure in itself is not necessarily associated with a bad result. These inexpensive, locally made unconventional systems, with the proper understanding of biomechanics and creation of appropriate load-sharing constructs, are as good as the conventional systems available today.

Adult↗
PubMed1994

Role of nitric oxide in esophageal peristalsis.

In vitro studies have suggested that NO may be a nonadrenergic, noncholinergic inhibitory mediator in the esophageal body. We examined the role of NO in physiological peristalsis in anesthetized opossums by assessing the effect of the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) on esophageal contractions induced by swallows, prolonged vagal efferent nerve stimulation, and midesophageal balloon distension. A perfused manometry system measured intraluminal pressures 1 and 5 cm orad to the lower esophagus, and suction electrodes monitored membrane potential changes at the same locations. NO synthase inhibition 1) decreased swallow-induced contraction amplitude in the distal esophagus and, when combined with atropine, abolished these contractions; 2) diminished swallow-induced contraction latencies, predominantly in the distal esophagus, thereby decreasing the latency gradient and increasing the peristaltic velocity; 3) abolished vagal-stimulation-induced, end-of-stimulus "B" contractions and either unmasked or increased the amplitude of intrastimulus "A" contractions; 4) abolished the contractions occurring at the end of balloon distension; and 5) inhibited the membrane hyperpolarization and the subsequent nonadrenergic, noncholinergic depolarization induced by all three stimuli. These data support the hypothesis that NO is a mediator of nonadrenergic, noncholinergic neurotransmission in the opossum esophagus. Furthermore, the data suggest that esophageal peristalsis is mediated by a "blended" activation of cholinergic and nonadrenergic, noncholinergic (via NO) neurons.

Animals↗
PubMed1994

p-Aminobenzene sulphonyl morpholine, compound 82/208 a new anticonvulsant agent.

p-Aminobenzene sulphonyl morpholine, compound 82/208, was evaluated for acute toxicity and anticonvulsant action in mice against tonic seizures induced by supramaximal electroshock and pentylene tetrazole and strychnine induced seizures and for its effect on blood pressure and respiration in cat. Diphenyl hydantoin (DPH) was used as reference standard. Compound 82/208 exhibited anticonvulsant activity against electroshock induced seizures and PTZ induced tonic seizures in mice. The compound had several distinct advantages over DPH in experimental evaluation in mice.

Animals↗
PubMed1993

Ankle fractures in the elderly: MUA versus ORIF.

A series of 80 patients over the age of 60 years with ankle fractures were reviewed retrospectively. 'Pilon' and talar fractures were excluded; 41 were treated conservatively (MUA) and 39 by operation (ORIF). The mean follow-up was 28 months (range 18-38 months) in the ORIF group and 25.5 months (range 12-40 months) in the MUA group. A statistically significant proportion of patients were satisfied with regard to pain, swelling, stiffness, instability and ranges of movement after ORIF. Anatomical congruity of the ankle mortice was better maintained following ORIF. Poor subjective and objective end results correlated with malalignment of the ankle mortice on the final radiograph at follow-up.

Aged↗
PubMed1992

Pharmacological characterization of lower esophageal sphincter relaxation induced by swallowing, vagal efferent nerve stimulation, and esophageal distention.

To characterize the neural pathways involved in lower esophageal sphincter relaxation, intraluminal pressures from the lower esophageal sphincter of the opossum were monitored during swallowing, vagal efferent nerve stimulation, and intraluminal balloon distention in the presence and absence of pharmacologic antagonism of putative neurotransmitters. The combination of atropine, hexamethonium, and 5-methoxydimethyltryptamine, which is known to block ganglionic transmission in the vagal inhibitory pathway to the lower esophageal sphincter, significantly antagonized LES relaxation induced by both swallowing and vagal stimulation, but did not affect the LES relaxation induced by balloon distention. Administration of the nitric oxide synthase inhibitor N omega nitro-L-arginine methyl ester, on the other hand, markedly inhibited LES relaxation induced by vagal stimulation, swallowing, and balloon distention, and this effect was reversed by administration of the nitric oxide synthase substrate L-arginine. These studies indicate that the distension-induced intramural pathway mediating LES relaxation does not involve ganglionic transmission similar to that of the vagal inhibitory pathway to the LES. However, the LES relaxation induced by all forms of stimuli appears to depend on nitric oxide as a final mediator.

Animals↗
PubMed1991

Susceptibility of glucose-6-phosphate dehydrogenase deficient red cells to primaquine, primaquine enantiomers, and its two putative metabolites. II. Effect on red blood cell membrane, lipid peroxidation, MC-540 staining, and scanning electron microscopic studies.

The effects of primaquine (PQ), its enantiomers [(+)PQ,(-)PQ] and hydroxy metabolites [5-hydroxyprimaquine (5HPQ) and 6-desmethyl-5-hydroxyprimaquine (6D5HPQ)] on cell membranes of glucose-6-phosphate dehydrogenase (G-6-PD) deficient red cells were studied in vitro. There was no significant effect of PQ on the malonyldialdehyde (MDA) content of normal and heterozygous red cells, but it caused a significant increase in MDA in G-6-PD deficient red cells (P less than 0.05). There was no noticeable difference between the effects of the two enantiomers on this variable (P greater than 0.05). Compared to PQ, the hydroxy metabolites produced a significantly greater increase in MDA in all the groups studied (P less than 0.001). Of the two hydroxy metabolites, 6D5HPQ was more toxic than 5HPQ. Staining with MC540 showed that exposure to PQ, its enantiomers and two putative metabolites produced significant fluorescence, indicating that the drug produces marked alterations in membrane fluidity. Although the fluorescence was seen both in normal and heterozygous cells, the effect was marked in hemizygous deficient red cells (P less than 0.001). Scanning electron microscopic (SEM) studies revealed that PQ enantiomers had a stomatocytic effect on red cells of normal, heterozygous and hemizygous G-6-PD deficient red cells, whereas the putative metabolites had an echinocytic effect. The effects were most pronounced in G-6-PD deficient red cells.

Erythrocyte Membrane↗
PubMed1991

Scanning of key residues in antibody binding sites by two saturation-mutagenesis approaches.

The complementarity-determining region 3 of the heavy chain (CDRH3) generally contributes the most to antibody-antigen binding. His101H in CDRH3 of the antibody Se155-4, which is specific for a trisaccharide epitope of Salmonella serotype B O-antigen, was mutated systematically into all nineteen other amino acids by a double mutation approach. Enzyme immunoassay (EIA) and affinity chromatography showed that the Asn, Gln, Gly and Ser mutants exhibited moderate to strong activity. Some mutants, such as Thr and Pro, had weak binding activity, while the acidic and hydrophobic amino acid substitutions resulted in complete loss of activity. A second mutation approach which randomly changed a selected residue into all other nineteen amino acids, while precluding wild-type transformants, is also described.

Amino Acid Sequence↗
PubMed1990

Synthesis and pharmacological studies of some (1,4)-naphthoquinono[3,2-c]-1H-pyrazoles, 2-substituted amino-1,4-naphthoquinones, and related compounds.

Series of (1,4)-Naphthoquinono(3,2-c)-1H-pyrazoles and 2-substituted amino-1,4-naphthoquinones have been synthesised and studied for their possible anticancer activity (animal tumours, Walker 256 carcinosarcoma), Influenza RNA transcriptase activity, antibiotic activity (C. neoformans, T. mentagraphytes, M. canis, A. niger, and C. albicans).

Antineoplastic Agents↗
PubMed1990

Anti-stress activity in a muramyl-dipeptide.

N-Acetylmuramyl-L-alanyl-D-isoglutamine and some of its derivatives have been examined for anti-stress activity. Amongst these, N-palmitoylmuramyl-L-alanyl-D-isoglutamine is shown to considerably enhance the capacity of animals to endure various types of stress. This indicates that besides acting as immunomodulators and sleep regulators, muramyl dipeptides may also act as anti-stress agents.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Comparative antifilarial efficacy of the N-oxides of diethylcarbamazine and two of its analogues.

The N-oxides of 1-diethyl carbamoyl-4-methyl piperazine (DEC), 3-ethyl-8-methyl, 1,3,8-triazabicyclo (4,4,0) decan-2-one (centperazine) and 1-methyl-4-(pyrrolidin-1-yl-carbonyl) piperazine (CDRI Comp. 72/70) have been evaluated against Limotosoides carinii infection in cotton rats to establish whether conversion of the three antifilarials into N-oxides would lead to exertion of better antifilarial activity. Of the three N-oxides, N-oxide of DEC showed significantly more suppressive effect on circulating microfilariae in comparison to its parent compound. However, adult worms were unaffected. It was observed that basicity of the N-CH3 group did not play major role in exertion of activity of DEC and related compounds. Nevertheless, two other N-oxides were inactive.

Animals↗
PubMed1989

Studies on 2,3,N,N'-substituted 4,4'-diaminodiphenylsulfones as potential antimalarial agents.

A series of new 4,4'-diaminodiphenylsulfones substituted at 2 and 3 position and also at primary amino group of the phenyl rings have been synthesized and evaluated for their antimalarial activity against Plasmodium berghei infection in mice. Some of these compounds were active and showed complete inhibition of parasitaemia which included 7a1-7a4, 7b3, 7b4 and 16a at 1 mg/kg i.p. for 4 days and 16a, at 0.3 mg/kg for 4 days. Some compounds tested for their synthetase inhibitory action in cell-free system isolated from P. berghei (7b1, 7b2 and 8b2) were found to be more active than diaminodiphenylsulphone. The difference in order of activity between these in vivo and in vitro tests may be due to differences in their pharmacokinetic properties.

Animals↗