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Biomedical subjects

E Thompson

Publications and source records attributed to E Thompson.

At least 145 records · Page 8Linked to original sources
PubMed1990

Consistent linkage of dominantly inherited osteogenesis imperfecta to the type I collagen loci: COL1A1 and COL1A2.

The segregation of COL1A1 and COL1A2, the two genes which encode the chains of type I collagen, was analyzed in 38 dominant osteogenesis imperfecta (OI) pedigrees by using polymorphic markers within or close to the genes. This was done in order to estimate the consistency of linkage of OI genes to these two loci. None of the 38 pedigrees showed evidence of recombination between the OI gene and both collagen loci, suggesting that the frequency of unlinked loci in the population must be low. From these results, approximate 95% confidence limits for the proportion of families linked to the type I collagen genes can be set between .91 and 1.00. This is high enough to base prenatal diagnosis of dominantly inherited OI on linkage to these genes even in families which are too small for the linkage to be independently confirmed to high levels of significance. When phenotypic features were compared with the concordant collagen locus, all eight pedigrees with Sillence OI type IV segregated with COL1A2. On the other hand, Sillence OI type I segregated with both COL1A1 (17 pedigrees) and COL1A2 (7 pedigrees). The concordant locus was uncertain in the remaining six OI type I pedigrees. Of several other features, the presence or absence of presenile hearing loss was the best predictor of the mutant locus in OI type I families, with 13 of the 17 COL1A1 segregants and none of the 7 COL1A2 segregants showing this feature.

Chromosomes, Human, Pair 17↗
PubMed1990

Functional ovarian cysts in patients cured of ovarian neoplasms.

Twenty-seven patients with ovarian cancer underwent unilateral salpingo-oophorectomy and were followed for 12-215 months (mean 80) after completion of therapy. Of these, nine patients who received pelvic irradiation subsequently developed ovarian failure. Of the remaining 18 patients who maintained ovarian function, 13 (72%) developed a functional ovarian cyst during the follow-up period. Of these 13 patients, eight were observed until the functional cyst regressed, four were treated with oral contraceptives (OCs) to suppress ovarian function, and one underwent oophorectomy for a large corpus luteum cyst. We recommend that OC pills be considered for suppression of ovarian function in postmenarcheal girls after completion of therapy for ovarian neoplasms. Routine use of OCs may simplify the follow-up of these patients by preventing the formation of functional ovarian cysts. In postmenarcheal patients not treated with OCs, the finding of a unilocular ovarian cyst should be considered to represent a functional cyst, and a trial of OCs for 3 months may result in spontaneous regression. Persistent cysts must be operatively removed.

Adolescent↗
PubMed1990

Joint estimation of recombination fractions and interference coefficients in multilocus linkage analysis.

Estimation of recombination fractions and interference coefficients is of importance in multilocus linkage analysis. With the development of molecular genetic technologies such as RFLP, multilocus data are readily available to researchers. Several methods have been developed to analyze such data, and each performs well under restrictive conditions. The present paper proposes a method based on a multiplicative model and maximum-likelihood estimation of recombination fractions and interference coefficients. The estimators are consistent regardless of the model assumptions and are efficient if the model is a good approximation. The estimators are tractable even when there are incomplete observations. Furthermore, the interference between nonadjacent chromosomal regions or those among three chromosomal regions can be modeled and tested by a simple Z-test. The proposed method was applied to linkage analysis of four-locus data obtained from Drosophila and that of seven-locus data obtained again from Drosophila. Reanalysis of the first example revealed that there is interference between chromosomal regions 2 and 3. Analysis of the second example suggested that there is triple interference as well as pairwise interference between nonadjacent chromosomal regions; the genetic interpretation of these findings remains to be developed.

Genetic Linkage↗
PubMed1989

A novel amino acid substitution in the reactive site of a congenital variant antithrombin. Antithrombin pescara, ARG393 to pro, caused by a CGT to CCT mutation.

Antithrombin is a plasma protein inhibitor that can be grouped within a serine proteinase inhibitor superfamily. Antithrombin Pescara is a functional variant of antithrombin found in a family with a high incidence of thrombosis. Preliminary functional analysis has suggested that the abnormality resides in the reactive site rather than in the heparin binding domain of the molecule. Accordingly, we have isolated the variant from plasma using heparin-Sepharose chromatography, followed by chromatography upon thrombin-Sepharose to remove the normal antithrombin that is present (the propositus is heterozygous for the variant). The variant protein was reduced, S-carboxy-methylated, and fragmented with CNBr. A pool ("CNBr pool 4") containing the reactive site region was isolated by reverse-phase high performance liquid chromatography and sequentially treated with trypsin and V8 protease. Fast atom bombardment-mass spectrometric analysis of this subdigest identified a novel peptide of mass 1708. Four steps of Edman degradation together with further analysis by fast atom bombardment-mass spectroscopy identified the NH2-terminal sequence of this peptide as Ala-Ala-Ala-Ser. The mass of the novel peptide and its changing mass in response to Edman degradation are only compatible with its identity as Ala382-Arg399, with the reactive site Arg393 replaced by Pro. Using specific oligonucleotide hybridization, we demonstrated that the molecular defect of antithrombin Pescara is caused by a CGT to CCT mutation in codon 393. These findings may be of broad interest, as other members of the serine protease inhibitor superfamily contain arginine at their reactive sites and may be expected to undergo a similar mutation.

Amino Acid Sequence↗
PubMed1989

The association of Angelman's syndrome with deletions within 15q11-13.

The inheritance of Angelman's syndrome, a disorder characterised by mental retardation, epilepsy, ataxia, and a happy disposition, is debated because affected sibs occur less frequently than expected with autosomal recessive inheritance. After discovering two unrelated patients with a small deletion of the proximal long arm of chromosome 15, 10 further patients with Angelman's syndrome were reassessed. Five had apparently normal karyotypes, four had a deletion within 15q11-13, and one had a pericentric inversion, inv(15)(p11q13) involving the same chromosomal region. In the latter case, the healthy mother had the same pericentric inversion, indicating that the patient also had a submicroscopic mutation on his other chromosome 15. These data map the Angelman locus to 15q11-13 and suggest that de novo visible deletions (associated with a low recurrence risk) and autosomal recessively inherited cases combine to give an overall sib recurrence risk of less than 25%.

Ataxia↗
PubMed1989

Dominantly inherited cleft lip and palate in two families.

Two families with non-syndromic cleft lip and cleft palate are described. The linear pattern of inheritance through several generations is difficult to explain by conventional multifactorial models. The pedigrees strengthen the suggestion that a dominantly inherited mutation exists with a major influence on clefting of the lip and palate alone.

Adult↗
PubMed1989

Severe Silver-Russell syndrome.

Three children are described with severe Silver-Russell syndrome. Major medical problems occurred in the first two years of life in all three. Silver-Russell syndrome should be considered in the differential diagnosis of children with severe pre- and postnatal growth deficiency.

Child, Preschool↗
PubMed1989

Increased serum CD8 antigen level in childhood Hodgkin's disease relates to advanced stage and poor treatment outcome.

Measurement of the soluble form of CD8 antigen, a surface membrane component of suppressor/cytotoxic T cells, has yielded useful information relevant to prognosis in the lymphoid malignancies of childhood. We therefore determined pretreatment levels of serum CD8 antigen in 90 children with newly diagnosed Hodgkin's disease. The findings ranged widely, from 220 to 2,585 U/mL (median, 556 U/mL). In patients with advanced disease (stage III or IV), the median serum CD8 level was significantly higher than in those with less disease extension (stage I or II): 675 v 477 U/mL, P = .003. It was also higher in children with B symptoms compared with all others: 622 v 494 U/mL, P = .005. Cases with a histologic classification of mixed cellularity had a significantly higher median level of the antigen than did those classified as nodular sclerosis: 847 v 509 U/mL, P = .005. Finally, higher serum CD8 levels (greater than 430 U/mL) were significantly associated with an increased probability of treatment failure (P = .02). In a multivariate analysis, serum CD8 level retained its impact on treatment outcome after adjustment for other potentially useful prognostic factors, including disease stage, presence of B symptoms, histology, erythrocyte sedimentation rate, sex, age, and race. The prognostic strength shown by soluble CD8 in this analysis suggests that the antigen has clinical value. We postulate that increased CD8 levels in serum indicate enhanced suppressor T-cell activity, which may compromise the host's antitumor immunity, leading to unusually aggressive disease.

Adolescent↗
PubMed1989

High serum interleukin-2 receptor levels correlate with a poor prognosis in children with Hodgkin's disease.

To improve the biologic evaluation of Hodgkin's disease, we determined serum interleukin-2 receptor (IL2R) levels in 88 children with this tumor. In patients with stage III or IV disease, the median receptor level was significantly higher than in patients with lower stages (3195 vs. 1087 U/ml, p = 0.0001). Similarly, the median level for children with stage B disease was 3262 U/ml, compared with 999 U/ml for those lacking constitutional symptoms (p = 0.0001). Patients with very high soluble IL2R levels (greater than or equal to 5000 U/ml) were significantly more likely to fail treatment (p = 0.01), even when the analysis was restricted to groups with advanced disease: stages III and IV (p = 0.0001). When entered in the Cox-proportional hazards model with other potentially useful prognostic factors, soluble IL2R level was found to be an independent predictor of treatment outcome. The relationship of high serum IL2R levels to an adverse clinical outcome in Hodgkin's disease may be explained by a model in which the soluble receptor competes for the ligand with the cellular receptor on normal lymphocytes, thus blocking antitumor immunity dependent on interleukin-2. Alternatively, high serum levels of IL2R may simply reflect increased release of the receptor from activated malignant cells in patients with advanced disease or an otherwise poor prognosis.

Adolescent↗
PubMed1988

Coordinate transcriptional regulation of alpha and delta chains of the T-cell antigen receptors by phorbol esters and cyclic adenosine 5'-monophosphate in human thymocytes.

The regulation of T-cell antigen receptor (TcR) gene expression by phorbol ester and cAMP was studied in human thymocytes. Incubation of human thymocytes in the presence of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate increased the levels of the mRNAs of TcR-alpha and -delta while the levels of TcR-beta and -gamma mRNA were not affected. cAMP, on the other hand, caused a decrease in TcR-alpha and -delta mRNA levels but also did not affect TcR-beta and -gamma mRNA levels. The induction of TcR-alpha and -delta mRNA by 12-O-tetradecanoylphorbol-13-acetate occurred at the transcriptional level only whereas cAMP treatment decreased both TcR-alpha gene transcription and the stability of its mRNA. The similarity in the transcriptional control of TcR-alpha and -delta genes combined with their close chromosomal location raises the possibility that they share common DNA regulatory elements.

Child↗
PubMed1988

Phorbol esters and calcium ionophores differentially regulate the transcription of gamma-T-cell antigen receptor gene in human thymocytes.

The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and the calcium ionophore ionomycin differentially regulated the expression of the gamma-T-cell antigen receptor (gamma-TCR) gene in human thymocytes. Ionomycin induced an increase in gamma-TCR mRNA while TPA prevented this effect. The effects of ionomycin and TPA are completely reversed upon their removal. Protein kinase C-depleted cells are unable to respond to TPA but the induction of gamma-TCR by ionomycin was unimpaired. The regulation of gamma-TCR gene expression by TPA and ionomycin occurred at the level of gene transcription, whereas the rate of gamma-TCR mRNA degradation was unaffected by TPA or ionomycin.

Child↗
PubMed1988

Interactions of adriamycin with a calcium binding site.

Terbium (Tb3+) luminescence has been used to investigate the interactions of adriamycin with a specific calcium binding protein, in the plasma membrane of GH3/B6 pituitary tumor cells. The luminescence intensity and lifetime of the Tb3+-GH3/B6 complex was quenched in the presence of adriamycin. According to Stern-Volmer analysis, the quenching of Tb3+-GH3/B6 luminescence was by both membrane bound adriamycin (Ka = 3.7 x 10(5) M-1) and free adriamycin (kq = 7.3 x 10(7) M-1 s-1). The data suggests that, the calcium binding site at the outer surface of the membrane is collisionally accessible to freely diffusing adriamycin; and, that the toxin receptor site is located near the bound metal ion.

Animals↗
PubMed1988

Randomised trial of prophylactic daily aspirin in British male doctors.

A six year randomised trial was conducted among 5139 apparently healthy male doctors to see whether 500 mg aspirin daily would reduce the incidence of and mortality from stroke, myocardial infarction, or other vascular conditions. Though total mortality was 10% lower in the treated than control group, this difference was not statistically significant and chiefly involved diseases other than stroke or myocardial infarction. Likewise, there was no significant difference in the incidence of non-fatal myocardial infarction or stroke--indeed, disabling strokes were somewhat commoner among those allocated aspirin. The lower confidence limit for the effect of aspirin on non-fatal stroke or myocardial infarction, however, was a substantial 25% reduction. Migraine and certain types of musculoskeletal pain were reported significantly less often in the treated than control group, but as the control group was not given a placebo the relevance of these findings was difficult to assess. There was no apparent reduction in the incidence of cataract in the treated group. The lack of any apparent reduction in disabling stroke or vascular death contrasts with the established value of antiplatelet treatment after occlusive vascular disease.

Aspirin↗
PubMed1988

Antagonistic effects of calcium ionophores and phorbol esters on T cell receptor mRNA levels in human thymocytes.

Levels of mRNA of the T cell antigen receptors (TcR) in human thymocytes are differentially regulated in response to distinct intracellular signals. Activation of protein kinase C by the phorbol ester, tetradecanoyl phorbol acetate or other phorbol esters increases the levels of the alpha and beta T cell receptor (TcR-alpha, TcR-beta) mRNA, whereas an increase in cytosolic free Ca2+, induced by ionomycin or other Ca2+ ionophores, results in a decrease of alpha and beta TcR mRNA levels. In contrast, ionomycin increases the expression TcR-gamma mRNA whereas tetradecanoyl phorbol acetate prevents this induction. Our results suggest the existence of two opposing intracellular pathways that control expression of TcR-alpha and TcR-beta mRNA levels, on the one hand and TcR-gamma mRNA, on the other. These results provide the first evidence for antagonistic actions of protein kinase C and cytosolic-free Ca2+ on gene expression.

Calcium↗