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Biomedical subjects

S Chakraverty

Publications and source records attributed to S Chakraverty.

27 records · Page 2Linked to original sources
PubMed1997

No association between polymorphisms in the human dopamine D3 and D4 receptors genes and alcoholism.

The human dopamine D2 receptor gene (DRD2) has received considerable attention for the past several years as a potential candidate that may affect susceptibility to alcoholism. The association studies that compared the frequencies of alleles of DRD2 gene between alcoholics and control groups have produced equivocal results. Dopamine D3 and D4 receptor genes (DRD3 and DRD4) are in the same class as DRD2 but with different pharmacological properties. We have used relative risk and haplotype relative risk approaches to test associations between alleles of DRD3 and DRD4 genes and alcoholism. For relative risk studies 162 probands from multiple incidence alcoholic families have been compared to 89 psychiatrically normal controls. Haplotype relative risk approaches have used 29 alcoholic probands in which both parents were available for genotyping. The Bal I restriction enzyme site in DRD3 and tandem repeat (VNTR) in DRD4 genes polymorphisms were used to genotype the above samples. The results of relative risk approaches for both DRD3 and DRD4 genes were negative for comparisons of alcoholics and subtypes of alcoholics with normal controls. Haplotype relative risk approaches also were negative for both genes. These results suggest that any role played by these receptors may account for only part of the variation in susceptibility to alcoholism.

Alcoholism↗
PubMed1996

Antibiotic prophylaxis in patients undergoing radiological procedures who are at risk of infective endocarditis--do radiologists know what they are doing?

The British Society for Antimicrobial Chemotherapy has published guidelines recommending that all patients with prosthetic heart valves, or those with a previous history of bacterial endocarditis, should receive prophylactic antibiotics before procedures likely to cause a bacteraemia, due to the potential risk of bacterial endocarditis. The guidelines are widely available, notably in the British National Formulary. Two separate and independent surveys of radiologists in this Region showed that there was poor awareness of these guidelines and their implications for radiology departments.

Anti-Bacterial Agents↗
PubMed1996

Antinociceptive profile of the pseudopeptide B2 bradykinin receptor antagonist NPC 18688 in mice.

1. The purpose of this study was to investigate the topical and systemic anti-hyperalgesic effect of the newly-developed pseudopeptide B2 receptor antagonist, NPC 18688, in different models of nociception in mice. 2. Given systemically 30 min beforehand, NPC 18688 (10-300 nmol kg-1, i.p.) caused no agonist effect, but produced a dose-related and significant inhibition of abdominal constrictions caused by intraperitoneal injection of acetic acid (0.6%), acetylcholine (ACh, 4.5 mg kg-1) or kaolin (50 mg kg-1). The calculated mean ID50s and the percentages of maximal inhibitions (MI) for these effects were: 77, 34 and > 300 nmol kg-1 and 65 +/- 6, 70 +/- 5 and 40 +/- 3%, respectively. The anti-hyperalgesic effect of NPC 18688 (100 nmol kg-1, i.p.) occurred rapidly (30 min) and lasted for at least 150 min. Hoe 140 (3-30 nmol kg-1, i.p.) given 30 min beforehand also inhibited, in a graded manner, acetic acid and ACh-induced writhing, with mean ID50s and MI of 6 and 9 nmol kg-1 and 56 +/- 7 and 62 +/- 6%, respectively. 3. NPC 18688 (10-300 nmol kg-1, i.p.) caused a graded inhibition of both phases of formalin (2.5%)-induced pain, its effects being more potent in relation to the second phase of the formalin test. The calculated mean ID50s and the MI were > 300 and 60 nmol kg-1 and 20 +/- 3 and 60 +/- 5% against the first and second phases of formalin-induced nociception, respectively. NPC 18688 at the same doses also inhibited, in a dose-related manner, formalin-induced paw oedema (MI of 35 +/- 3%). 4. When injected locally in the mouse paw, NPC 18688 (2, 10 and 20 nmol/paw) had no agonist activity. However, when co-injected with formalin NPC 18688 (2-20 nmol/paw), it produced significant inhibition of both phases of formalin response, with MI of 40 +/- 3 and 33 +/- 2%, respectively. NPC 18688 at 10 nmol/paw also significantly inhibited formalin-induced paw oedema (25 +/- 2%). 5. Given intraperitoneally, NPC 18688 (30-300 nmol kg-1) determined a graded inhibition of the nociceptive response caused by intraplantar injection of capsaicin (1.6 micrograms/paw) (40 +/- 2%). However, NPC 18688 (up to 300 nmol kg-1, i.p.), given 30 min beforehand, had no significant analgesic effect when analyzed in the tail flick and in the hot plate pain models, nor did it change the performance of animals in the rota rod test. 6. The action of NPC 18688 was quite selective for the B2 receptor, and like Hoe 140, (1 to 100 nmol kg-1, i.p.) it caused graded inhibition of bradykinin (BK, 3 mol/paw)-induced increase in mouse paw volume, with mean ID50s of 61 and 6 nmol kg-1, respectively. In addition, at 100 nmol kg-1, the dose at which NPC 18688 significantly antagonized BK (3 nmol)-mediated rat paw oedema in naive animals, it had no significant effect on des-Arg9-BK (100 nmol/paw)-induced oedema in paws that had been desensitized to BK. NPC 18688 (210 nmol kg-1), like Hoe 140 (230 nmol kg-1) given s.c. 30 min beforehand, completely abolished BK (28 nmol)-induced hypotension, without affecting the fall of mean arterial blood pressure induced by i.v. injection of ACh (2 nmol kg-1). Finally, NPC 18688 (1 microM) did not affect ACh-mediated contraction in the guinea-pig ileum or toad rectus abdominii in vitro. 7. These results demonstrate that the newly-developed and selective pseudopeptide B2 receptor antagonist, NPC 18688, although less potent than the available second generation of B2 peptide BK receptor antagonists, exhibits topical and long-lasting systemic anti-hyperalgesic properties when analysed in several models of nociception in mice, making it a useful tool for investigating the participation of BK and related kinins in physiological and pathological processes. Finally, this new class of selective pseudopeptide B2 receptor antagonist may constitute a new strategy for developing the third generation of potent and long-lasting orally-active non-peptide BK antagonists, which may be useful for the management of clinical disorders involving BK and relate

Acetylcholine↗
PubMed1995

Possible association between the dopamine D3 receptor gene and bipolar affective disorder.

A variety of studies have reported possible genetic associations between bipolar affective disorder and different loci using relative risk (case-control) comparisons. An alternative approach is to construct a contrast group using parental alleles which were not transmitted to an affected individual [Falk and Rubinstein, 1987: Ann Hum Genet 51:227-233]. We have used both approaches to test for possible associations between alleles of the dopamine D3 receptor gene and bipolar affective disorder. For relative risk studies, the probands of multiple incidence bipolar affective disorder families have been compared to alcoholic and psychiatrically normal contrast groups. Nontransmitted allele approaches have used bipolar affective disorder and alcoholic probands in which both parents were available for genotyping. Using the BalI restriction enzyme site polymorphism of Lannfelt et al. [1992: Psychiatr Genet 2:249-256], we have found no differences in the allele or genotype frequencies for bipolar vs. alcoholic or psychiatrically normal controls. In contrast, we have found evidence for an increased frequency of allele 1 and allele 1 containing genotypes in transmitted alleles from bipolar families.

Adult↗
PubMed1995

Cerebrotendinous xanthomatosis in two sisters: case reports and MR imaging.

Cerebrotendinous xanthomatosis is a rare inherited disorder of bile acid metabolism producing xanthomata and severe, progressive neurological deficits. In spite of the rarity of the condition it is important because it is treatable: the neurological deterioration can be halted and in some cases reversed.

Adult↗
PubMed1994

Preparation of the colon for double-contrast barium enema: comparison of Picolax, Picolax with cleansing enema and Citramag (2 sachets)--a randomized prospective trial.

A randomized prospective trial was undertaken on 196 consecutive patients referred for double-contrast barium enema examination to assess the relative efficacy of three colon cleansing regimes: Citramag (2 sachets), Picolax and Picolax with a preliminary cleansing enema. Each of the regimes was preceded by a 5 day low residue diet. The radiographs from the examinations were assessed on a double-blind basis. The quality of bowel preparation was significantly poorer (P < 0.001) in the group receiving the preliminary cleansing enema, notably with respect to mucosal coating, compared with the other two groups. The quality of the preparation was slightly better in the group receiving Picolax alone than in the Citramag group (P < 0.01), the difference being most apparent in the proximal colon. The laxatives were equally well tolerated. The study has formed the basis of a departmental audit. As a result, the bowel preparation has been standardized to a 5 day period of dietary restriction followed by 2 Picolax sachets. This measure has improved efficiency within the department with no sacrifice in quality.

Adult↗
PubMed1986

Purification, solubility, and pKa of veratridine.

The alkaloid neurotoxin veratridine is widely used by cell physiologists to increase membrane sodium permeability. The compound is only sporadically available from commercial sources, but can be purified (Kupchan et al., 1953, J. Amer. Chem. Soc. 75, 5519-5524) from veratrine, a mixture of several alkaloids. We describe here a purification procedure only slightly modified from that of Kupchan et al., and include important details not mentioned in the original paper. Ultraviolet and infrared spectra are presented. We have also determined the pKa and solubility of veratridine in 150 mM NaCl at 25 degrees C. The solubility is steeply pH dependent, ranging from 0.61 +/- 0.02 mM above pH 12 to 18.5 mM at pH 8.07. The pKa, determined from the solubility versus pH curve, was found to be 9.54 +/- 0.02.

Hydrogen-Ion Concentration↗