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K Roberts

Publications and source records attributed to K Roberts.

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

GTP causes calcium release from a plant microsomal fraction.

Studies on a variety of animal cell types have revealed a GTP-specific calcium-releasing mechanism in a non-mitochondrial, microsomal fraction. Here we report that GTP also induces rapid release of calcium from a zucchini (Cucurbita pepo L.) hypocotyl microsomal fraction. Maximal release occurs at 50 microM, and half-maximal release at 8 microM GTP. GTP is highly specific in its effect, and may not be replaced by UTP, ATP, CTP, TTP, GMP, or by non-hydrolysable analogues of GTP. Reuptake of calcium after release does not normally occur; however, this may be induced by non-hydrolysable GTP analogues. Calcium release is also blocked by prior treatment with these analogues.

Adenosine Triphosphate↗
PubMed1989

The clinical correlates of serum CA125 in 169 patients with epithelial ovarian carcinoma.

Serial CA125 measurements in 169 patients with epithelial ovarian carcinoma were obtained. Changes in serum CA125 measurements are shown to reflect changes in clinical status. For patients with macroscopic disease receiving chemotherapy, the sensitivity and specificity for predicting response are shown to be 95% and 86% respectively. For patients with no known disease, the sensitivity and specificity for detecting relapse are shown to be 86% and 91% respectively. The clinical correlates with the level of serum CA125 were examined and the most important is shown to be amount of residual disease.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1989

A family of abundant plasma membrane-associated glycoproteins related to the arabinogalactan proteins is unique to flowering plants.

We have identified a family of abundant peripheral plasma membrane glycoproteins that is unique to flowering plants. They are identified by a monoclonal antibody, MAC 207, that recognizes an epitope containing L-arabinose and D-glucuronic acid. Immunofluorescence and immunogold labeling studies locate the MAC 207 epitope to the outer surface of the plasma membrane both in protoplasts and in intact tissues. In some cells MAC 207 also binds to the vacuolar membrane, probably reflecting the movement of the plasma membrane glycoproteins in the endocytic pathway. The epitope recognized by MAC 207 is also present on a distinct soluble proteoglycan secreted into the growth medium by carrot (Daucus carota) suspension culture cells. Biochemical evidence identifies this neutral proteoglycan as a member of the large class of arabinogalactan proteins (AGPs), and suggests a structural relationship between it and the plasma membrane glycoproteins. AGPs have the property of binding to beta-glycans, and we therefore propose that one function of the AGP-related, plasma membrane-associated glycoproteins may be to act as cell surface attachment sites for cell wall matrix polysaccharides.

Blotting, Western↗
PubMed1989

The prognostic significance of the half-life of serum CA 125 in patients responding to chemotherapy for epithelial ovarian carcinoma.

Various prognostic factors were studied in 29 patients with stage III or IV ovarian cancer who responded to initial chemotherapy after initial diagnostic surgery. The half-life of CA 125 in serum during initial chemotherapy was the most important prognostic indicator for survival (P less than 0.001) and the chance of achieving complete remission (P = 0.012). A CA 125 half-life of less than 20 days, 20-40 days and greater than 40 days appears to identify patients with a good, intermediate or poor prognosis, the two year actuarial survival being 76%, 48% and 0% respectively. The change of achieving a complete remission was 15% and 67% respectively for patients with a serum CA 125 half-life of greater than 20 or less than 20 days.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1989

Duchenne muscular dystrophy in Wales: impact of DNA linkage analysis and cDNA deletion screening.

A register of families with Duchenne muscular dystrophy (DMD) has been maintained in Wales since 1973. Since 1986 we have attempted to refine carrier status, and when necessary offer prenatal diagnosis, for those at significant risk by using intragenic probes. cDNA probes were included from the beginning of 1988. Thirty-four (30%) of the 115 women tested were assigned a risk of carrying the DMD gene of less than 5%. Thirty-three (29%) of the women at 5% or greater risk are now able to have prenatal diagnosis using a molecular deletion; such deletions were detected in 50% of affected boys. The remaining women could have prenatal diagnosis using a linked intragenic probe with an error rate varying between 0.25% and 9%. In 19 cases DNA samples from DMD boys who were dead at the time of analysis were used, indicating that it is essential to bank DNA from all males affected by DMD. We conclude that a large proportion of women at risk of carrying the DMD gene can now be helped by DNA studies.

Chromosome Deletion↗
PubMed1989

Testosterone induction of cellular proteins in cultured Sertoli cells from hypophysectomized rats and rats of different ages.

Testosterone is essential for the maintenance of spermatogenesis, and the Sertoli cell is thought to be an important target cell for the hormone in the seminiferous tubule. The direct response of Sertoli cells to testosterone in cell culture was studied by two-dimensional gel electrophoresis of radiolabeled cellular proteins. Changes in testosterone responsiveness with age and hormonal condition were studied by culturing Sertoli cells from 20- and 40-day-old normal rats and 40-day-old rats that had been hypophysectomized at 20 days of age. Two abundant proteins, numbered 1604 and 1605 for reference purposes, were consistently increased in response to testosterone treatment in all three sets of cultured Sertoli cells. Two other proteins, 1602 and 1603, were decreased with testosterone in all three Sertoli cell cultures. Densitometric scanning of the gels revealed changes in several proteins of low abundance (i.e. proteins that represent less than 0.2% of the total incorporated radioactivity on the gel) in response to testosterone. The majority of the changes in response to testosterone were in these low abundance proteins. Protein profiles from testosterone-treated cell cultures as well as control (no hormone) Sertoli cell cultures differed among the three groups of cells. This indicates that differences in Sertoli cell function in vivo due to age and hormonal condition are reflected in culture by protein profiles.

Aging↗
PubMed1989

Accuracy and precision of analyses for total cholesterol as measured with the Reflotron cholesterol method.

We compared plasma cholesterol measurements made with the Boehringer Mannheim Reflotron reflectance photometric analyzer in 1298 capillary blood samples with measurements made in venous blood samples collected at the same time and analyzed in four standardized Lipid Research Clinics laboratories. The Reflotron measurements averaged 0.8% to 7.8% lower than the laboratory values. Correlations (r) between the two sets of measurements ranged from 0.92 to 0.96. In some samples, however, the Reflotron values differed from the laboratory values by greater than or equal to 12%; the cholesterol concentrations in these samples tended to be higher than in those for which better agreement was observed. The smaller negative biases were observed when test strips were used that were calibrated with reference to the Centers for Disease Control Reference Method for cholesterol. The agreement between sequential Reflotron values averaged less than or equal to 4.3%. There was an average difference of less than or equal to 1.0% between Reflotron measurements made in each of two sequential capillary blood samples taken from a single finger puncture.

Cholesterol↗
PubMed1988

Presence of guanine nucleotide-binding proteins in a plant hypocotyl microsomal fraction.

The presence of specific guanine nucleotide-binding proteins in a zucchini (Cucurbita pepo L.) hypocotyl microsomal fraction was investigated. Polypeptides were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis and transferred to nitrocellulose. Incubation of nitrocellulose blots with [alpha-32P]GTP and [gamma-32P]GTP indicated the presence of four specific and distinct GTP-binding proteins with molecular masses of approx. 23.4 kDa, 24.8 kDa, 26.6 kDa and 28.5 kDa. Binding of [alpha-32P]GTP could be completely prevented by 30 microM GDP or 10 microM guanosine 5'[gamma-thio]triphosphate. This report presents evidence for the presence in a microsomal fraction from zucchini hypocotyls of Gn-proteins as defined by Bhullar and Haslam (1987) Biochem.J. 245, 617-620. The four plant proteins resemble animal Gn-proteins when molecular weights and GTP-binding specificities are considered.

Adenosine Triphosphate↗
PubMed1988

Sports participation and health status: a preliminary analysis.

This paper presents fresh evidence which examines health in relation to age, sex, socio-economic status, sport type and frequency amongst indoor sports participants. The evidence is from 4441 self-completed questionnaires by representative samples of adult participants in seven indoor sports at 46 separate sports facilities, in six U.K. cities. Six indicators of the respondents' health were inter-related and, for purposes of this analysis, are combined into a six-point scale, Males and females in all age groups who were taking part in the more physically demanding sports recorded the highest health scores. In addition, individuals who were playing these demanding sports more than once per week scored higher than those participating in the same activities less often. Health score was also found to be associated with other health-promoting lifestyle practices, such as never smoking and moderate alcohol consumption. Longitudinal corroboration will be necessary to confirm sport as a causal factor in the health-sport relationship, though the cross-sectional evidence from this enquiry is encouraging. It suggests that all types of physically demanding sport, competitive or not, offer measurable health gains to men and women of all ages and whatever their broader ways of living.

Adolescent↗
PubMed1988

Transferrin and sulfated glycoprotein-2 messenger ribonucleic acid levels in the testis and isolated Sertoli cells of hypophysectomized rats.

Both FSH and testosterone act on Sertoli cells in the testis. It is possible that the action of these hormones on Sertoli cells results in an increased capacity for the cells to carry out their prescribed functions, among which are the synthesis and secretion of specific glycoproteins. Changes in the testicular levels of two specific mRNAs in hypophysectomized hormone-treated rats were determined by solution hybridization to cRNA probes. The mRNAs coding for transferrin and sulfated glycoprotein-2 (SGP-2), both of which are secretion products of Sertoli cells, decreased dramatically in the testis of hypophysectomized rats that were maintained for 20 days untreated with hormones. If hypophysectomy was done to rats at 20 days of age, daily injections for a subsequent 20 days with FSH or FSH in combination with testosterone partially maintained both transferrin and SGP-2 mRNA levels. Testosterone alone was ineffective in 20-day-old rats. In contrast, if hypophysectomy was performed on 40-day-old rats, daily injections of testosterone alone or in combination with FSH were most effective in maintaining higher levels of the specific mRNAs. When the Sertoli cells from rats hypophysectomized at 20 days of age were placed in cell culture, FSH again was most effective in the stimulation of transferrin mRNA above control levels. However, when the Sertoli cells from the rats hypophysectomized at 40 days of age were placed in culture, FSH was slightly stimulatory, but testosterone had no effect on the transferrin mRNA levels. Neither FSH nor testosterone affected the levels of SGP-2 mRNA in the cultured cells regardless of the age of the animal at the time of hypophysectomy. Additional in vivo studies were done in which the rats were hypophysectomized at 20 days of age, allowed to regress for 17 days, and then injected daily with hormones for 3 days. The levels of transferrin and SGP-2 mRNA in this experiment were stimulated by FSH alone or by a combination of FSH and testosterone to an extent similar to that in the cultured cells. These studies showed that FSH is most important in the younger rats and testosterone is most important in the older rats in the maintenance of specific mRNA levels. In addition, the level of stimulation observed with either hormone is different depending on whether the hormone is given in culture or in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Interleukin 2 promotes conjugate formation by purified LAK precursors and T lymphocytes: evaluation of conjugates using flow cytometric techniques.

The capacity of null cells, enriched in natural killer cells and lymphokine-activated killer (LAK) cell precursors, and T cells to conjugate with tumor targets was analyzed using a flow cytometric assay. Both purified null and T lymphocytes had a similar capacity to conjugate with uncultured and cultured tumor targets prior to interleukin-2 (IL-2) stimulation. In addition, the frequency of conjugation did not correlate with the cytotoxicity expressed by these purified lymphocyte subpopulations, as null but not T cells were highly lytic for the K562 target. Following incubation in IL-2, however, the level of conjugation with tumor targets of both null and T lymphocytes was increased. Both effector populations formed stable conjugates within 6 min at 37 degrees C. The promotion of conjugation was associated with the induction of LAK activity by null but not T lymphocytes. No differences were apparent between the capacity of either IL-2-activated null or IL-2-activated T lymphocytes to conjugate with tumor targets, although only the former efficiently lysed them. Conjugation of both null and T effectors with tumor targets required the presence of Mg2+ cations because it was inhibited by the presence of EDTA (38-72% inhibition) but not EGTA. Conjugation was also inhibited by an antibody (MHM 23) recognizing the beta-chain shared by LFA-1, MAC-1, and P150/95 molecules. These observations demonstrate that both null and T lymphocytes responded to IL-2 with an increase in their ability to conjugate with tumor targets. The frequent formation of stable conjugates under these conditions by cells with both cytolytic and noncytolytic capacity failed to define conjugation as the only major condition proximate to LAK lysis.

Antigens, Differentiation↗
PubMed1988

X-linked hypohidrotic ectodermal dysplasia: localization within the region Xq11-21.1 by linkage analysis and implications for carrier detection and prenatal diagnosis.

X-linked hypohidrotic ectodermal dysplasia (H.E.D.) is a disorder of abnormal morphogenesis of ectodermal structures and is of unknown pathogenesis. Neither relatively accurate carrier detection nor prenatal diagnosis has been available. Previous localization of the disorder by linkage analysis utilizing restriction-fragment polymorphisms, by our group and others, has placed the disorder in the general pericentromeric region. We have extended our previous study by analyzing 36 families by means of 10 DNA probes at nine marker loci and have localized the disorder to the region Xq11-Xq21.1, probably Xq12-Xq13. Three loci--DXS159 (theta = .01, z = 14.84), PGK1 (theta = .02, z = 13.44), and DXS72 (theta = .02, z = 11.38)--show very close linkage to the disorder, while five other pericentromeric loci (DXS146, DXS14, DXYS1, DXYS2, and DXS3) display significant but looser linkage. Analysis of the linkage data yields no significant evidence for nonallelic heterogeneity for the X-linked form of the disorder. Both multipoint analysis and examination of multiply informative meioses with known phase establish that the locus for H.E.D. is flanked on one side by the proximal long arm loci DXYS1, DXYS2, and DXS3 and on the other side by the short arm loci DXS146 and DXS14. Multipoint mapping could not resolve the order of H.E.D. and the three tightly linked loci. This order can be inferred from published data on physical mapping of marker loci in the pericentromeric region, which have utilized somatic cell hybrid lines established from a female with severe manifestations of H.E.D., and an X/9 translocation (breakpoint Xq13.1). If one assumes that the breakpoint of the translocation is within the locus for H.E.D. and that there has not been a rearrangement in the hybrid line, then DXS159 would be proximal to the disorder and PGK1 and DXS72 would be distal to the disorder. Both accurate carrier detection and prenatal diagnosis are now feasible in a majority of families at risk for the disorder.

Chromosome Mapping↗
PubMed1987

Separation and functional studies of the human lymphokine-activated killer cell.

Cell separation studies were undertaken in an attempt to purify the lymphokine-activated killer (LAK) precursor cell. Null cells, prepared by the sequential depletion of monocytes, T- and B-lymphocytes from human peripheral blood mononuclear cells, were found to be potent mediators of LAK activity. Such preparations were Leu-11+ but Leu-4- and displayed high levels of natural killer activity. Incubation of these cells with recombinant interleukin 2 (IL-2) for periods in excess of 24 h induced LAK lysis of fresh tumor targets which were resistant to lysis by unstimulated null effectors. In contrast, lymphocytes which formed high affinity rosettes with sheep RBC (E+ lymphocytes) were poor mediators of both natural killer and LAK activity. Interleukin 2 stimulated null cells, retained a Leu-11+, Leu-4- phenotype, and expressed only low levels of receptors for IL-2 and transferrin. An increase in the number of binding sites, on null cells but not on T-cells, for Vicia villosa lectin with IL-2 stimulation was noted. Following IL-2 stimulation, null and T-cells were able to conjugate to K562 and fresh tumor but not to autologous lymphoblast targets.

Carbohydrates↗
PubMed1987

X-linked hypohidrotic ectodermal dysplasia: DNA probe linkage analysis and gene localization.

A linkage study of 24 families with hypohidrotic (anhidrotic) ectodermal dysplasia (HED) has been performed. The previously suggested linkage to DXYS1 has been confirmed, and linkage to probes DXS14 and DXS3 has been established. We suggest that the HED locus lies in the centromeric region between DXYS1 on the long arm and DXS14 on the short arm of the X chromosome, probably on proximal Xq.

Chromosome Mapping↗
PubMed1987

Specific binding and lysis of human melanoma by IL-2-activated cells coated with anti-T3 or anti-Fc receptor cross-linked to antimelanoma antibody: a possible approach to the immunotherapy of human tumors.

Monoclonal antibodies (MoAb) to human melanoma have demonstrated a limited ability to cause tumor regression in humans when used alone or when coupled to gamma-emitting radioisotopes. We have evaluated heteroaggregates containing antilymphocyte antibodies crosslinked to antimelanoma monoclonal antibodies recognizing p97, a transferrin-like molecule (MoAb 96.5). When coupled to antibodies recognizing T3 (CD3, part of the T-cell receptor complex for antigen) or to 3G8, an antibody recognizing the Fc receptor present on large granular lymphocytes and granulocytes (CD16), significant induction of effector target crosslinks and target cell lysis could be obtained. Effector cells incubated for 24 hr with recombinant IL-2 were coated with the crosslinked reagents and tested for conjugate formation and for cytotoxicity in a 4-hr assay with chromium-labeled targets. Marked increases in conjugation to autologous tumor (47.0% compared to 11.8%) was demonstrated with E+ cells using the T3-coupled MoAb and with E- cells using the Fc receptor-coupled MoAb (22.6% compared to 11.2%). When tested in sequential cytotoxicity assays using unseparated effector cells incubated for 1, 2, and 3 days in IL-2, lytic activity was less than 2, less than 2, and 3.3 LU/10(6) cells for cells incubated in monomeric 96.5; 2.6, 5.3, and 50 LU/10(6) cells incubated in 96.5 crosslinked T3; and less than 2, 3.6, and 8.0 LU/10(6) cells for cells incubated with 96.5 crosslinked to 3G8. Similar findings were noted in two other experiments. Heteroaggregates such as these may be useful in conjunction with the transfer of IL-2-activated cells or with IL-2 alone in immunotherapy trials.

Antibodies, Monoclonal↗