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Biomedical subjects

S Deb

Publications and source records attributed to S Deb.

At least 145 records · Page 8Linked to original sources
PubMed1989

Granuloma formation in Schistosoma japonicum infected nude mice: the effects of reconstitution with L3T4+ or Lyt2+ splenic cells.

The role of L3T4+ and Lyt2+ lymphocytes in the formation and modulation of granulomas around Schistosoma japonicum eggs was examined in athymic mice. Nude C57BL/6 mice infected with S. japonicum miracidia were compared to nude mice given normal spleen cells depleted of L3T4+ or Lyt2+ cells prior to infection and to intact mice. Nude mice formed small granulomas that were poor in eosinophils and connective tissue. Nude mice reconstituted with cells enriched for L3T4+ or Lyt2+ cells formed granulomas similar in size to those in intact mice, but granulomas in mice given Lyt2+ cells contained few eosinophils and had significantly less collagen than did granulomas in mice given L3T4+ cells. The same was true at 10 weeks. Mice reconstituted with null cells were examined at 7 weeks and formed granulomas similar to those in mice given Lyt2+ cells. By 10 weeks after infection, granulomas had decreased to the same minute size in all groups of mice. Fibrosis increased at weeks 7-10 in all groups of mice.

Animals↗
PubMed1988

A 67-base-pair segment from the Ori-S region of herpes simplex virus type 1 encodes origin function.

The Ori-S segment of herpes simplex virus type 1 contains a 45-base-pair-long imperfect palindrome with an AT segment at its center. We cloned Ori-S into a poisonless plasmid to investigate the role of the palindromic components in DNA replication. Neither a large insertion within the AT segment nor a deletion of the right side of the palindrome significantly inhibited DNA replication under our conditions of analysis. These findings argue against the necessity for a specific cruciform structure in the initiation of replication. We scanned the entire AT segment with triple tandem-base-pair substitutions to pinpoint essential functional sequences. Only the first 3 base pairs at the left end of the segment are absolutely essential for replication in the presence of the remaining AT sequences.

Base Sequence↗
PubMed1987

Simian virus 40 large tumor antigen requires three core replication origin domains for DNA unwinding and replication in vitro.

Simian virus 40 (SV40) large tumor antigen (T antigen) unwinds DNA containing the SV40 origin of replication. The origin requirement for unwinding can be satisfied by the 64-base-pair SV40 core origin that supports T-antigen-dependent DNA replication both in vivo and in vitro. The core origin contains three domains with specific DNA sequence features. These include an inverted repeat, a central T-antigen binding domain, and an adenine- and thymine-rich domain containing a DNA bending focus. The domain and spacer requirements of the core origin for DNA unwinding and replication in vitro are strikingly similar to the origin requirements for DNA replication in vivo. Thus, each of the three functional domains of the core origin contributes directly to the initiation of duplex DNA unwinding by T antigen.

DNA Helicases↗
PubMed1987

Folate metabolism and problem behaviour in mentally handicapped epileptics.

Two groups of mentally handicapped residents were studied consisting of 32 epileptics on anti-epileptic medication and 32 non-epileptic controls. The epileptic group showed a significantly low serum folate level compared with the non-epileptic control group. Serum vitamin B12 and behaviour rating did not show any significant difference between two groups. Comparison of patients receiving phenytoin and those who were not showed significantly lower serum folate in the sub-group receiving phenytoin, but there was no significant difference between the sub-groups with respect to vitamin B12 or behaviour problem rating.

Adolescent↗
PubMed1987

The T-antigen-binding domain of the simian virus 40 core origin of replication.

The simian virus 40 origin of replication contains a 27-base-pair palindrome with the sequence 5'-CA-GAGGC-C-GAGGC-G-GCCTC-G-GCCTC-TG-3'. The four 5'-GAGGC-3'/5'-GCCTC-3' pentanucleotides are known contact sites for simian virus 40 T-antigen binding in vitro. We used oligonucleotide-directed cassette mutagenesis to identify features of this palindrome that are important for the initiation of DNA replication in vivo. Each base pair of a pentanucleotide is crucial for DNA replication. In contrast, sequences adjacent to pentanucleotides have little or no effect on replication. Thus, the pentanucleotide is the basic functional unit, not only for T-antigen binding but also for DNA replication. All four pentanucleotides are indispensable in the initiation process. The spacing of pentanucleotides is crucial because duplication of the single base pair between binding sites has a far greater effect on replication than does substitution of the same base pair. Inversion of any pentanucleotide blocks DNA synthesis. Thus, the pentanucleotide is not a functionally symmetrical unit. We propose that each pentanucleotide positions a monomer of T antigen at the proper distance, rotation, and orientation relative to other T-antigen monomers and to other origin domains and that such positioning leads to subsequent events in replication.

Antigens, Polyomavirus Transforming↗
PubMed1987

A case of mosaicism with fragile-X and XXY components.

The case of a 63-year-old severely mentally handicapped man is reported with chromosomal mosaicism. His karyotype was established as mosaic 46XY/47XXY with the fragile site present in a proportion of cells of both cell-lines. He showed phenotypic features which could be related both to the fragile-X and Klinefelter's syndromes.

Fragile X Syndrome↗
PubMed1986

Expression of ras oncogene p21 in prostate cancer.

The major neoplastic transformation-inducing genes of human solid tumors are members of the ras oncogene family. We used an immunohistochemical assay to assess expression of both the unaltered and the mutated ras oncogene protein (p21) in normal and neoplastic prostatic cells. With the concentration of monoclonal antibody used in this study, epithelial and stromal cells from subjects with normal prostates and from 19 patients with benign prostatic hyperplasia were negative for p21 antigen. This antigen was detected in 2 of 6 prostates with Grade I carcinoma, 4 of 6 with Grade II, and all of 17 with higher grades. A semiquantitative immunohistochemical method demonstrated that expression of the p21 antigen in a carcinoma strongly correlated with nuclear anaplasia and was inversely related to the degree of glandular differentiation. However, markedly anaplastic tumors were often more heterogeneous in expression of p21 and contained areas of low staining for the antigen. Comparison of p21 antigen with tumor carcinoembryonic antigen and prostate-specific antigen demonstrated that ras p21 was the only phenotypic marker that correlated with histologic tumor grade. Thus, ras oncogene p21 may represent a new class of biologically relevant tumor markers and may be a useful adjunct to histopathologic examination in determining the prognosis of patients with prostate cancer.

Antigens, Neoplasm↗
PubMed1986

Isolation of differentiated membrane domains from Escherichia coli and Salmonella typhimurium, including a fraction containing attachment sites between the inner and outer membranes and the murein skeleton of the cell envelope.

Cell envelopes of Salmonella typhimurium and Escherichia coli were disrupted in a French pressure cell and fractionated by successive cycles of sedimentation and floatation density gradient centrifugation. This permitted the identification and isolation of several membrane fractions in addition to the major inner membrane and murein-outer membrane fractions. One of these fractions (fraction OML) accounted for about 10% of the total cell envelope protein, and is likely to include the murein-membrane adhesion zones that are seen in electron micrographs of plasmolyzed cells. Fraction OML contained inner membrane, murein, and outer membrane in an apparently normal configuration, was capable of synthesizing murein from UDP-[3H]N-acetylglucosamine and UDP-N-acetylmuramylpentapeptide and covalently linking it to the endogenous murein of the preparation, and showed a labeling pattern in [3H]galactose pulse-chase experiments that was consistent with its acting as an intermediate in the movement of newly synthesized lipopolysaccharide from inner membrane to outer membrane. The fractionation procedure also identified two new minor membrane fractions, with characteristic protein patterns, that are usually included in the region of the major inner membrane peak in other fractionation procedures but can be separated from the major inner membrane fraction and from contaminating flagellar fragments by the subsequent floatation centrifugation steps.

Bacterial Proteins↗
PubMed1986

Functional interactions of the simian virus 40 core origin of replication with flanking regulatory sequences.

We constructed a matched set of plasmids to investigate the interactions of essential core sequences of the simian virus 40 replication origin with flanking regulatory sequences. Deletions of either T-antigen-binding region I or the 21-base-pair repeated promoter elements reduced replication to 50 to 70% of wild-type levels. The simultaneous deletion of both regions decreased replication to less than 5% of wild-type levels. Thus, the double deletion greatly amplified the defects of the single deletions. We conclude that region I and the 21-base-pair repeats have related rather than independent functions in DNA synthesis. Insertion of a synthetic region I or the adenovirus 2 major late promoter at the late side of isolated core sequences in place of the 21-base-pair repeats failed to restore replication. In contrast, insertion of a single 72-base-pair enhancer element stimulated replication of the core origin more than fivefold. Thus, three distinct regulatory elements appear to facilitate core DNA replication by related mechanisms. Flanking sequences have only a small direct effect on T-antigen binding to naked core DNA. Possible mechanisms of action include the regulation of transcription or of chromatin structure.

Adenoviridae↗
PubMed1986

The adenine-thymine domain of the simian virus 40 core origin directs DNA bending and coordinately regulates DNA replication.

The simian virus 40 origin of replication contains a 20-base-pair adenine-thymine-rich segment with the sequence 5'-TGCATAAATAAAAAAAATTA-3'. The continuous tract of eight adenines is highly conserved among polyomaviruses. We used single-base substitutions to map structural and functional features of this DNA. Mutations in the AAA and AAAAAAAATT sequences significantly reduce DNA replication and thus identify two sequence-specific functional domains or a single domain with two parts. The AAAAAAAATT sequence also determines a DNA conformation that is characteristic of DNA bending. Single-base mutations in this domain change the degree of net bending, presumably by altering the length and location of the bending sequence. Thus, DNA bending in the correct conformation and location may be a structural signal for replication in polyomavirus origins and perhaps in other origins of replication with consecutive runs of adenines. The first five base pairs (TGCAT) of the 20-base-pair segment and the T between the AAA and AAAAAAAATT domains serve a sequence-independent function that may establish proper spacing within the core origin.

Adenine↗
PubMed1986

Domain structure of the simian virus 40 core origin of replication.

The simian virus 40 core origin of replication consists of nucleotides 5211 through 31. These 64 base pairs contain three functional domains with strict sequence requirements and two spacer regions with relaxed sequence specificity but precise positional constraints. The early domain extends for 10 contiguous base pairs between nucleotides 5211 and 5220. A 9-base pair spacer from sequences 5221 through 5229 separates the early domain from the 23-base pair central palindrome that directs the binding of T antigen. The late end of the core between nucleotides 12 and 31 also contains spacer and sequence-specific functions that are not yet completely mapped. We propose that the sequence-specific domains are interaction sites for viral and cellular proteins, determinants of DNA conformation, or both. The spacers would position these signals at required distances and rotations relative to one another.

Base Sequence↗
PubMed1985

ras Oncogene p21 expression is increased in premalignant lesions and high grade bladder carcinoma.

ras Oncogene p21 antigen is present in the most superficial cells of the normal bladder urothelium, as demonstrated by immunohistochemical staining. The pattern and intensity of p21 staining of cells in epithelial hyperplasia and low grade bladder carcinoma were similar to that seen in the normal urothelium. In contrast, epithelial cells in "premalignant" (dysplastic) lesions and high grade carcinomas exhibited an intense staining reaction for p21 antigen. ras p21 may be a useful marker for the malignant potential of both premalignant lesions and carcinomas of the bladder.

Adult↗
PubMed1985

Bioassay of fish gonadotrophin by ovarian mitochondrial cholesterol depletion.

Murrel (Channa punctatus Bloch) ovarian tissues were incubated in vitro with or without piscine gonadotrophins and then subjected to subcellular fractionation followed by nonesterified cholesterol (cholesterol) assay. Gonadotrophin from salmon (SG-G100), tilapia (TL1MS), and sturgeon (S27MS) depleted cholesterol in the mitochondrial fraction, whereas cholesterol remained unchanged in other subcellular fractions. Aminoglutethimide, an inhibitor of mitochondrial cholesterol side-chain cleavage, blocked the depletion of mitochondrial cholesterol in response to SG-G100 and murrel pituitary extract. When ovarian tissue containing [4-14C]cholesterol was challenged with SG-G100 in vitro, a dose-dependent decrease of mitochondrial [4-14C]cholesterol was observed. Increasing concentrations (1, 2, 4, 6, or 8 micrograms/incubation) of SG-G100, TL1MS, and S27MS resulted in a clear linear depletion of mitochondrial cholesterol. The slope of the dose-response curve in different individual fish was found to be distinctly uniform and parallel. The slopes of the standard curves obtained with TL1MS and S27MS were greater than that with SG-G100, indicating that tilapia and sturgeon gonadotrophins are more potent. Carp pituitary gonadotrophin content, determined by using these standard curves, showed the sensitivity and precision of this bioassay.

Aminoglutethimide↗
PubMed1985

Calcium homeostasis in mentally handicapped epileptic patients.

Three groups of subjects have been studied to evaluate the role of long term hospitalization and chronic anti-epileptic therapy on calcium metabolism. The first group consisted of 32 epileptic patients, randomly selected from a population of inpatients in a hospital for the mentally handicapped, receiving various combinations of anti-epileptic drugs for at least 3 years. The second group was made up of 32 non-epileptic residents of the same hospital, individually matched for age and sex with epileptic patients and who had not received any anti-epileptic drugs in the last 3 years. The third group of 22 normal subjects was randomly selected from the staff of the University Hospital of Wales, matched for age and sex against the epileptic group, who had not received any anti-epileptic medication within the last 3 years. None of the subjects received any drugs (except anti-epileptic drugs) known to have effect on calcium metabolism. Significant differences in the serum levels of the total calcium, ionised calcium, total alkaline phosphatase and its liver iso-enzyme were seen. Serum total alkaline phosphatase and its liver iso-enzyme were significantly elevated in the epileptic group, showing the effect of anti-epileptic drugs. On the other hand serum total calcium was significantly lower in both residential groups compared to the normal population, epileptics being lower than non-epileptics showing the combined effect of hospitalization and anti-epileptic drugs. No significant difference was detected among the groups in the serum concentration of the bone alkaline phosphatase iso-enzyme.

Adolescent↗
PubMed1983

Interrelationship between plasma and ovarian cholesterol in a teleost fish.

The profiles of plasma and ovarian cholesterol altered similarly as a result of seasonal influence. Fish pituitary extract and LH significantly depleted plasma and ovarian free cholesterol only, esterified cholesterol remaining unaltered. Findings indicated that plasma cholesterol was the primary source of sterol for ovarian steroidogenesis.

Animals↗