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D D Patel

Publications and source records attributed to D D Patel.

At least 19 recordsLinked to original sources
PubMed1995

Characterization of human CD7 transgenic mice.

CD7 is a 40-kDa transmembrane glycoprotein member of the lg gene superfamily expressed on most peripheral blood T lymphocytes and NK cells. CD7 is also expressed on myeloid, NK, B, and T cell precursors during adult hematopoiesis. Because Thy-1 is absent in human thymocytes and peripheral blood T cells and shows structural similarities to the human CD7 gene, we have suggested that human CD7 may be a functional homologue in humans of mouse Thy-1. To study the tissue-specific expression of the CD7 gene utilizing its own promoter, we constructed transgenic mice that contained both the coding and flanking regions of the human CD7 gene. We found that human CD7 was expressed in transgenic mice in T, B, NK, and myeloid lineages and was induced with T cell activation. Unlike the expression of CD7 in humans, the CD7 transgene was present on mature B lymphocytes and macrophages. Like mouse Thy-1, transgenic human CD7 was expressed in immature and mature T cells and in Sca-1+ bone marrow mononuclear cells. Unlike mouse Thy-1, the human CD7 transgene was not expressed in mouse brain or fibroblasts. The human CD7 transgene was expressed during fetal development before mouse Thy-1 in fetal liver mononuclear cells. Expression of the human CD7 transgene did not alter mouse thymopiesis or Thy-1 expression. Taken together, these data demonstrated that the CD7 transgene contained sufficient regulatory regions to direct hematopoietic expression and mitogenic induction. The pattern of CD7 transgene expression more closely resembled that of CD7 in humans than that of mouse Thy-1.

Animals↗
PubMed1995

Identification and characterization of a 100-kD ligand for CD6 on human thymic epithelial cells.

CD6 is a 130-kD glycoprotein expressed on the surface of thymocytes and peripheral blood T cells that is involved in TCR-mediated T cell activation. In thymus, CD6 mediates interactions between thymocytes and thymic epithelial (TE) cells. In indirect immunofluorescence assays, a recombinant CD6-immunoglobulin fusion protein (CD6-Rg) bound to cultured human TE cells and to thymic fibroblasts. CD6-Rg binding to TF and TE cells was trypsin sensitive, and 54 +/- 4% of binding was divalent cation dependent. By screening the blind panel of 479 monoclonal antibodies (mAbs) from the 5th International Workshop on Human Leukocyte Differentiation Antigens for expression on human TE cells and for the ability to block CD6-Rg binding to TE cells, we found one mAb (J4-81) that significantly inhibited the binding of CD6-Rg to TE cells (60 +/- 7% inhibition). A second mAb to the surface antigen identified by mAb J4-81, J3-119, enhanced the binding of CD6-Rg to TE cells by 48 +/- 5%. Using covalent cross-linking and trypsin digestion, we found that mAb J4-81 and CD6-Rg both bound to the same 100-kD glycoprotein (CD6L-100) on the surface of TE cells. These data demonstrate that a 100-kD glycoprotein on TE cells detected by mAb J4-81 is a ligand for CD6.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed1995

Characterization of human thymic epithelial cell surface antigens: phenotypic similarity of thymic epithelial cells to epidermal keratinocytes.

Cellular interactions between developing thymocytes and cells of the thymic microenvironment are necessary for maturation of thymocytes into mature T cells. While much is known about the molecules on developing T cells that mediate these interactions, little is known about the surface molecules of human thymic epithelial (TE) cells. In this study, using a panel of 276 MAb including 255 MAb from the 5th International Workshop on Human Leukocyte Differentiation Antigens (HLDA-V), we have determined the expression of CD1 through CDw130 and other surface molecules on resting and IFN-gamma-activated cultured human TE cells and on resting epidermal keratinocytes (EK). We demonstrate the surface expression of 50 of the 161 molecules assayed for on TE cells, including a number of adhesion molecules, cytokine receptors, Apo-1, and MHC-encoded molecules. While activation of TE cells with IFN-gamma for 48 hr induced a greater than fivefold increase in the expression of four surface molecules (CD38, CD54, MHC class I, and MHC class II), it also induced a greater than 50% increase in the expression of 14 other surface molecules (CD12, CD29, CD40, CD44, CD47, CD49b, CD49c, CD49e, CD55, CD66, CD87, CD104, TE4, and STE3) and a decrease in the expression of three molecules (CDw65, CDw109, and STE2). In comparing the phenotype of TE cells to 83 other cell lines studied in HLDA-V, we found that TE cells were strikingly more similar to EK than to any of the other cell types tested.

Antigens, CD↗
PubMed1995

Expression of CD44 molecules and CD44 ligands during human thymic fetal development: expression of CD44 isoforms is developmentally regulated.

It has recently been recognized that CD44 comprises a large family of alternatively spliced forms. In the thymus, CD44 has been postulated to play an important role in immature T cell migration and maturation. In this paper, we have studied the expression of CD44 molecules and two CD44 ligands, hyaluronan (HA) and fibronectin (FN), during human thymic fetal development. We found that mAbs against all CD44 isoforms (A3D8 or A1G3) reacted with both thymic epithelial (TE) cells and thymocytes beginning at the time of initial colonization of the human thymus by hematopoietic stem cells at 8.2 weeks of fetal gestation. However, mAbs specific for splice variants of CD44 containing membrane-proximal inserts (11.24, 11.10 and 11.9) reacted only with terminally differentiated TE cells in and around Hassall's bodies beginning at 16-19 weeks of fetal gestation. Studies of differentiated versus undifferentiated TE cells in vitro confirmed the selective expression of CD44 variant isoforms on terminally differentiated TE cells. Expression of HA and FN was determined by fluorescence microscopy using either biotinylated-HA binding protein or an anti-FN mAb. We found that whereas FN was present throughout the human fetal thymus beginning at 8.2 weeks, HA was not present until 16 weeks of gestational age. These data demonstrate the differential expression of standard versus variant CD44 isoforms during thymic ontogeny and implicate CD44 interactions with ligands other than HA as important in the earlier stages of human thymus development.

Antibodies, Monoclonal↗
PubMed1992

Site-specific RNA cleavage generates the 3' end of a poxvirus late mRNA.

The cowpox virus late mRNAs encoding the major protein of the A-type inclusions have 3' ends corresponding to a single site in the DNA template. The DNA sequence of the Alu I-Xba I fragment at this position encodes an RNA cis-acting signal, designated the AX element, which directs this RNA 3' end formation. In cells infected with vaccinia virus the AX element functions independently of either the nature of the promoter element or the RNA polymerase responsible for generating the primary RNA. At late times during virus replication, vaccinia virus induces or activates a site-specific endoribonuclease that cleaves primary RNAs within the AX element. The 3' end produced by RNA cleavage is then polyadenylylated to form the 3' end of the mature mRNA. Therefore, the poxviruses employ at least two mechanisms of RNA 3' end formation during the viral replication cycle. One mechanism, which is operative at early times in viral replication, involves the termination of transcription [Rohrmann, G., Yuen, L. & Moss, B. (1986) Cell 46, 1029-1035]. A second mechanism, which is operative at late times during viral replication, involves the site-specific cleavage of primary RNAs.

Base Sequence↗
PubMed1992

Comparison of plasma prolactin and CEA in monitoring patients with adenocarcinoma of colon and rectum.

Plasma prolactin (PRL) and carcinoembryonic antigen (CEA) were measured by radioimmunoassay in 74 patients with adenocarcinoma of colon and rectum. The markers were correlated with disease stage, histological grade and progression/remission of disease. The circulating preoperative median PRL and CEA levels were significantly higher in colorectal cancer patients than in their respective controls. PRL was elevated in all Dukes stages and in all histological grades of the tumour whereas the rise in CEA was more pronounced in Dukes D. Out of 74 patients, 29% (21/74) developed recurrent disease and 31% (23/74) responded to the treatment. With regard to monitoring recurrence(s), the predictive value of PRL was 94% which was significantly greater than that of CEA which was only 62%. In patients who developed liver metastases PRL remained elevated whereas CEA showed more than 100-fold increase. Therefore, we feel that CEA is a better marker for monitoring patients who developed liver metastases. From our results, we suggest that PRL can be used as a better overall marker for detecting recurrence(s) in patients with colorectal adenocarcinoma.

Adenocarcinoma↗
PubMed1992

Characterization of two new point mutations in the low density lipoprotein receptor genes of an English patient with homozygous familial hypercholesterolemia.

Two new point mutations have been detected in the low density lipoprotein (LDL) receptor gene of a patient with a clinical diagnosis of homozygous familial hypercholesterolemia (FH). The patient is a compound heterozygote, in whom the mutant allele inherited from his English father has a single base substitution of A for G in exon 3, changing the codon for residue 80 in the mature protein from glutamic acid to lysine. The mutant allele inherited from his mother, who is of Irish origin, has a single base pair deletion in the codon for residue 743 in exon 15 that causes a frameshift and introduces a new stop codon in the adjacent position. The glu80 to lys mutation results in a transport-defective phenotype and a mature protein that migrates abnormally slowly on nonreduced SDS-PAGE, but normally under reducing conditions; this was confirmed by site-directed mutagenesis and expression in vitro. The deletion in exon 15 results in a null phenotype in which the putative truncated receptor protein cannot be detected in cultured skin fibroblasts and the amount of mRNA derived from the allele is reduced. The glu80 to lys mutation was found in a further five unrelated individuals in a sample of 200 FH patients from the London area and in 11 from a sample of 77 FH patients from Manchester. Haplotype analysis suggested that all the patients had inherited this allele from a common ancestor. The deletion in exon 15 was not found in the London sample, nor in any unrelated individuals in the Manchester sample.

Alleles↗
PubMed1992

Endocrine status in stage II vs. advanced premenopausal and postmenopausal breast cancer patients.

Circulating preoperative levels of DHEA-S, androstenedione and SHBG were measured in 40 premenopausal and 49 postmenopausal breast cancer patients, and in 30 and 15 age-matched healthy controls, respectively. Moreover, the levels of LH, FSH, prolactin, estradiol, progesterone, testosterone, DHEA-S, androstenedione and SHBG of Stage II breast cancer patients were compared with advanced patients and also with controls. In premenopausal patients the levels of steroid hormones were significantly low whereas those of peptide hormones were significantly high. On the contrary, in postmenopausal patients, except DHEA-S, all other hormones were significantly elevated in comparison with controls. In premenopausal patients, DHEA-S, androstenedione, estradiol, progesterone, and testosterone decreased as stage advanced with concomitant increase of SHBG, LH, FSH and prolactin when compared with hormone levels of Stage II patients. In postmenopausal advanced breast cancer patients, when compared with Stage II patients, the levels of SHBG, LH, FSH, and prolactin increased significantly, while DHEA-S, androstenedione, estradiol, and progesterone decreased as stage advanced.

Androstenedione↗
PubMed1992

Estrogen and progesterone receptor status of primary breast cancer: relationship with the pattern of first metastasis and survival.

Estrogen (ER) and progesterone receptor (PR) contents in primary tumors from 127 advanced breast cancer patients were measured by DCC method. The patients were followed for 2 years and the prognostic value of the receptor levels was evaluated and compared with other tumor and patient characteristics. No relation was found between receptor levels and tumor, first relapse site as well as short-term survival (2 years) which might be due to the advanced stage of disease at diagnosis.

Adult↗
PubMed1992

Endocrine function in premenopausal and postmenopausal advanced breast cancer patients treated with CMF or tamoxifen.

The effect of CMF (cyclophosphamide, methotrexate and 5-fluorouracil) or tamoxifen treatment on endocrine function was investigated in premenopausal and postmenopausal breast cancer patients. CMF therapy resulted in ovarian failure but pituitary and adrenal functions were unaffected in premenopausal patients. Although amenorrhea was achieved within two to five months in older patients, younger patients required large cumulative doses of cytotoxic drugs to exhibit ovarian dysfunction. CMF therapy had no effect on hormonal levels in postmenopausal patients indicating that in this group therapeutic response is not mediated via the endocrine system. On the other hand, tamoxifen therapy in postmenopausal patients resulted in hyperestrogenemia.

Adult↗
PubMed1990

Plasma prolactin as an indicator of disease progression in advanced breast cancer.

Serial plasma prolactin levels were measured in 144 breast cancer patients (premenopausal [PR-M], N = 64; postmenopausal [PO-M], N = 80) and compared with respective controls. Patients with breast cancer were grouped into those who (1) developed distant metastasis, (2) developed local recurrence, (3) stable disease, and (4) responded to the various therapeutic modalities at the end of 2 years. The authors' analysis showed excellent correlation between serial plasma prolactin changes and the response to therapy or progression of disease in patients with advanced breast carcinoma.

Biomarkers, Tumor↗
PubMed1990

Fine structure mapping and phenotypic analysis of five temperature-sensitive mutations in the second largest subunit of vaccinia virus DNA-dependent RNA polymerase.

We have used plasmid clones spanning the region encoding the 132-kDa subunit of the cowpox virus RNA polymerase (CPV rpo 132) to marker rescue each of five vaccinia virus (VV) temperature sensitive (ts) mutants, ts 27, ts 29, ts 32, ts 47, and ts 62, which together constitute a single complementation group. The experiments fine-map the vaccinia mutations to a 1.3-kb region containing the 3' end of the CPV rpo 132 gene. Phenotypic characterization shows that all five mutants are affected to varying extents in their ability to synthesize late viral proteins at the nonpermissive temperature, similar to other ts mutants with lesions in the 22- and the 147-kDa subunits of the VV RNA polymerase. Two mutants, ts 27 and ts 32, exhibit a delay in the synthesis of late viral proteins at both the permissive and the nonpermissive temperatures. We conclude that the five VV mutants affect the 132-kDa subunit of the VV RNA polymerase. Additional genetic experiments demonstrate intragenic complementation between ts 62 and three other members of this complementation group, ts 27, ts 29, and ts 32.

Animals↗
PubMed1989

Defective processing and binding of low-density lipoprotein receptors in fibroblasts from a familial hypercholesterolaemic subject.

The properties of the low-density lipoprotein (LDL) receptor were studied in skin fibroblasts from a homozygous familial hypercholesterolaemic subject, MM (MM cells), who exhibits a defect in the processing of the precursor form of the receptor. Despite the prolonged half-life of the precursor (3 h), essentially all was eventually processed to the mature form, which was degraded with a half-life of approximately 6 h. The receptor content of the MM cells, determined by radioimmunoassay, was slightly lower than normal and by immunoblotting it was estimated that 55% was present as the mature form at equilibrium. The mature receptor reached the cell surface and was internalized and recycled apparently normally, with about 60% accessible to pronase at any time. Immunoblotting, immunoassay and surface labelling with 125I all indicated that the cells contained twice as much surface receptor protein as would be expected from the binding of LDL. Maximum heparin-releasable LDL binding to MM cells was 20% of normal and the apparent affinity for LDL was reduced. The cells did not show the marked increase in affinity and reduction in binding exhibited by normal cells when cooled to 4 degrees C. Also, neither the apparent affinity of the receptors nor the maximum binding at 37 degrees C was greatly affected by an antibody that has been shown to reduce the affinity and halve the binding of normal cells. The results suggest that the mutation in the LDL receptor gene of these cells affected the ability of the receptors to bind LDL in a similar manner to the antibody, possibly by promoting aggregation of receptors on the cell surface, and halving the amount of LDL bound.

Adult↗
PubMed1989

Identification of a point mutation in growth factor repeat C of the low density lipoprotein-receptor gene in a patient with homozygous familial hypercholesterolemia that affects ligand binding and intracellular movement of receptors.

The coding region of the low density lipoprotein (LDL)-receptor gene from a patient (MM) with homozygous familial hypercholesterolemia (FH) has been sequenced from six overlapping 500-base-pair amplified fragments of the cDNA from cultured skin fibroblasts. Two separate single nucleotide base changes from the normal sequence were detected. The first involved substitution of guanine for adenine in the third position of the codon for amino acid residue Cys-27 and did not affect the protein sequence. The second mutation was substitution of thymine for cytosine in the DNA for the codon for amino acid residue 664, changing the codon from CCG (proline) to CTG (leucine) and introducing a new site for the restriction enzyme PstI. MM is a true homozygote with two identical genes, and the mutation cosegregated with clinically diagnosed FH in his family in which first cousin marriages occurred frequently. The amino acid change occurs in the center of growth factor repeat C in the epidermal growth factor precursor-homology domain of the protein, a region of highly conserved sequence between bovine and human LDL receptors, and results in slowed, but complete, maturation of the precursor to the mature form of the receptor and, despite its remoteness from the ligand-binding domain, in impaired binding of LDL. LDL receptors in MM's skin fibroblasts bind less LDL than normal and with reduced affinity. Thus this naturally occurring single point mutation affects both intracellular transport of the protein and ligand binding and occurs in growth factor-like repeat C, a region that has not previously been found to influence LDL binding.

Amino Acid Sequence↗
PubMed1989

The second-largest subunit of the poxvirus RNA polymerase is similar to the corresponding subunits of procaryotic and eucaryotic RNA polymerases.

We have characterized the poxvirus gene encoding the second-largest subunit of the viral DNA-dependent RNA polymerase. This gene, designated rpo132, is located in the HindIII A fragment of the DNA of the Brighton Red strain of cowpox virus. A similar gene is located in the corresponding position in the HindIII A fragment of the DNA of the Western Reserve strain of vaccinia virus. The rpo132 gene is transcribed throughout the viral multiplication cycle. It has two transcriptional start sites; one is operative at late times only, and the other (80 base pairs downstream) is operative both at early times and at late times. Neither early nor late transcripts originating from the latter RNA start site contain long 5'-terminal poly(A) sequences. The rpo132 gene has the capacity to encode primary gene products of two types. The RNA transcripts whose 5' ends correspond to the early RNA start site can encode a 133-kilodalton (kDa) protein. The RNA transcripts whose 5' ends correspond to the early RNA start site can encode a 132-kDa protein. Transcripts of the latter type are more abundant, suggesting that the 132-kDa protein is the major primary product of this gene. The predicted amino acid sequences of both gene products share extensive similarities with the amino acid sequences of the second-largest subunits of the following enzymes: the RNA polymerase of Escherichia coli, the RNA polymerase II of Saccharomyces cerevisiae, and the RNA polymerase II of Drosophila melanogaster. This result provides further evidence of relatedness between multisubunit DNA-dependent RNA polymerases.

Amino Acid Sequence↗
PubMed1988

Low-density-lipoprotein-receptor mRNA content of fibroblasts from normal and familial hypercholesterolaemic subjects.

The amount of mRNA for the low-density-lipoprotein (LDL) receptor in cultured human fibroblasts was estimated by hybridization of the poly(A)-rich RNA fraction with a DNA probe, using the recovery of beta-actin mRNA to correct for losses. During incubation of the cells with lipoprotein-deficient serum (LPDS) both the LDL-receptor mRNA content and the rate of receptor protein synthesis increased fourfold during the first 16 h and then fell by approximately 50% during the next 24 h. The content of beta-actin mRNA fell by a similar amount, so that the ratio of receptor/beta-actin mRNAs rose and then remained constant. The fall in beta-actin mRNA content during incubation with LPDS was not prevented by the addition of cholesterol to the medium. In cells from a homozygous familial hypercholesterolaemic (FH) subject that bound 20% of the normal amount of LDL, the content of LDL-receptor mRNA and the changes during incubation with LPDS or free sterols were similar to normal. Cells from a familial hypercholesterolaemic subject that produced no immunodetectable receptor protein produced a small amount of receptor mRNA of apparently normal size which responded in the same way as in normal cells to LPDS and free sterols.

Actins↗
PubMed1988

Increased frequency of sister chromatid exchanges in lymphocytes of breast cancer patients.

Spontaneous and mitomycin-C (MMC)-induced rates of sister chromatid exchanges (SCEs) were studied in peripheral blood lymphocytes (PBLs) of 40 patients with cancer of the breast and 40 healthy female volunteers as controls. Spontaneous SCE per cell value in PBL cultures was 7.72 for the breast cancer patients, which was significantly higher (p less than 0.001) than the 6.28 SCEs per cell scored for the controls. Eight of the patients were studied a second time, 3 to 6 months following surgical removal of the tumour. A significant (p less than 0.05) reduction in SCE per cell value was observed following mastectomy. MMC-induced frequencies of SCE remained comparable in patients and controls. Cellular kinetics, calculated as average generation time (AGT) from the frequency of cells in M1, M2 and M3 cycles, were comparable in patients and controls.

Adult↗