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Biomedical subjects

D Sen

Publications and source records attributed to D Sen.

At least 37 records · Page 2Linked to original sources
PubMed1989

Clinical & bacteriological profiles of shigellosis in Calcutta before & after an epidemic (1984-87).

Patients below 5 yr of age, hospitalised for shigellosis over a period of four years (1984-87), were studied. During the epidemic of bacillary dysentery (1984) isolation of different Shigella spp. as well as Shigella dysenteriae type 1 was high. Decreased isolation of Sh. dysenteriae type 1 and increased isolation of Sh. flexneri was observed during post-epidemic years (1985-87). Isolation of different Shigella spp. was always above 25 per cent from patients with dysentery and greater than 7 per cent from those with watery diarrhoea during the post-epidemic years. Higher incidence of shigellosis was observed amongst older children (greater than 3 yr). Most of the shigellosis patients complained of blood and mucus in stools. Vomiting was common among shigellosis patients presenting with watery diarrhoea whereas fever was commonly seen in patients with both dysentery and watery diarrhoea. Most patients of shigellosis presenting with blood and mucus in stools had no dehydration.

Child, Preschool↗
PubMed1988

Formation of parallel four-stranded complexes by guanine-rich motifs in DNA and its implications for meiosis.

We have discovered that single-stranded DNA containing short guanine-rich motifs will self-associate at physiological salt concentrations to make four-stranded structures in which the strands run in parallel fashion. We believe these complexes are held together by guanines bonded to each other by Hoogsteen pairing. Such guanine-rich sequences occur in immunoglobulin switch regions, in gene promoters, and in chromosomal telomeres. We speculate that this self-recognition of guanine-rich motifs of DNA serves to bring together, and to zipper up in register, the four homologous chromatids during meiosis.

Base Sequence↗
PubMed1986

Influence of DNA-binding drugs on chromatin condensation.

We have used transient electric dichroism to study the ability of DNA-binding drugs to affect the folding of chromatin from the 10- to the 30-nm fiber, either by themselves or in conjunction with multivalent cations. Variables considered include the cationic charge of the drug, the comparative influence of intercalation and groove binding as modes of interaction, and the effect of bis-intercalation compared to mono-intercalation. In parallel with our findings with other cations, we observe that a drug must have a charge of 3+ or greater in order to condense chromatin at concentrations substantially lower than the concentration of chromatin, measured in base pairs. Drugs of low charge, whether groove binders or mono-or bis-intercalators, are unable to condense chromatin on their own. Bis-intercalators of high charge, however, are extremely efficient condensers, being able to cross-link chromatin with greater efficiency than polyamines of corresponding charge. When Mg2+ is used in combination with bis-intercalators of high charge, the order of addition of the two determines whether compaction or cross-linking is favored. Finally, the antibiotics actinomycin D, daunomycin, and distamycin, despite varied modes of binding to DNA, all inhibit the compaction of chromatin beyond a critical point in a remarkably similar manner.

Animals↗
PubMed1986

Rectal histology in acute bacillary dysentery.

A recent epidemic of acute Shigella dysentery in West Bengal (India) provided us with an opportunity to examine the rectal mucosal abnormalities seen in this condition. One hundred two patients were investigated using sigmoidoscopy, rectal biopsy, and rectal swab for culture. Pure culture of Shigella was obtained in 37 cases, and the rectal biopsy specimens from these patients were assessed in detail. The mean (+/- SD) duration of illness was 47.8 +/- 27.4 h (range 8-120 h), and most patients (31 of 37, 84%) had diarrhea with blood and mucus in the stools. Significant findings at histology were as follows. (a) Cellular infiltrate was predominantly round cell or mixed round cell and neutrophilic in the majority of patients (27, 73%). (b) Disorganization of crypts was seen in as many as 31 patients (84%); in most subjects the distorted architecture was mild, but in a few the defect was severe with crypt branching and dilatation. (c) In the majority of patients the inflammatory process extended to the muscularis mucosae and submucosa; edema with or without increased cellular infiltrate was seen in the muscularis mucosae in 92% and in the submucosa in 80%. (d) There was no difference in the rectal histology of patients with a short history of disease (less than 48 h) compared with those with a longer history, except for goblet cell depletion which was more in those with diarrhea for more than 48 h. (e) The mucosal abnormalities in patients with watery diarrhea were, in general, milder than in those with dysentery, although the difference was statistically not significant; 2 of 6 patients with watery diarrhea had severe colitis. (f) The mucosal abnormalities were more severe in patients with Shigella dysenteriae infection compared with Shigella flexneri.

Adolescent↗
PubMed1978

Effect of doxycycline on transmission of Vibrio cholerae infection among family contacts of cholera patients in Calcutta.

Doxycycline was used among the family contacts of hospitalized cholera patients in Calcutta to determine its effectiveness in controlling transmission of V. cholerae infection. A total of 137 such contacts were given a single oral dose of doxycycline in graded doses according to age. A similar group of 139 contacts received a single dose of multivitamins as placebo. All 276 contacts were examined bacteriologically daily for 10 days for the presence of V. cholerae in their stools. The results showed that doxycycline was effective in significantly reducing the load of V. cholerae infection for up to 5 days following treatment.

Adolescent↗