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Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 451 records · Page 25Linked to original sources
PubMed1992

[Selective attention in major depression: clinical retardation and cognitive inhibition].

Relationships between clinical retardation (measured by the Hamilton Depression Inventory) and selective attention (measured with a computerized version of the Stroop word colour test) were studied in a population of 21 depressed patients. Stroop interference was higher in depressed patients than in normals. Desynchronized presentations of the distractor and the target and intervals between responses and succeeding stimuli permitted depressed subjects to respectively apply and lift inhibition of the distractor so that their interference was reduced to control levels. Finally, successive inhibition scores were correlated with the retardation score in depressed subjects. The results are consistent with the hypothesis of a retardation in the application and the lifting of cognitive inhibition in depression.

Adult↗
PubMed1991

Cytotoxic properties of DAB486EGF and DAB389EGF, epidermal growth factor (EGF) receptor-targeted fusion toxins.

Elevated expression of the receptor for epidermal growth factor (EGF) is a characteristic of several malignancies including those of the breast, bladder, prostate, lung, and neuroglia. To therapeutically target the cytotoxic action of diphtheria toxin to EGF receptor-expressing tumor cells, we have constructed a hybrid gene in which the sequences for the binding domain of diphtheria toxin have been replaced by those for human EGF. The resulting fusion toxins, DAB486EGF and DAB389EGF, bind specifically to the EGF receptor and inhibit protein synthesis in a variety of EGF receptor expressing human tumor cell lines with an IC50 as low as 0.1 pM. Comparisons of DAB486EGF and DAB389EGF showed that DAB389EGF was consistently 10- to 100-fold more cytotoxic than DAB486EGF. Like diphtheria toxin, the cytotoxic action of DAB389EGF results from ADP-ribosylation of elongation factor-2 and is sensitive to the action of chloroquine. Studies of the kinetics of cellular intoxication showed that a 15-min exposure of EGF receptor-expressing A431 cells to DAB389EGF results in complete protein synthesis inhibition within 4 h. Furthermore, inhibition of protein synthesis results in elimination of human tumor cell colonies. These findings show that DAB389EGF is a potential therapeutic agent for a wide variety of EGF receptor-expressing solid tumors.

Adenosine Diphosphate Ribose↗
PubMed1991

Expression in Escherichia coli and characterization of the heat-stable inhibitor of the cAMP-dependent protein kinase.

Pure heat-stable inhibitor of the cAMP-dependent protein kinase (PKI) has been isolated in high yield by using a bacterial expression vector constructed to synthesize the complete sequence of the rabbit muscle protein kinase inhibitor, plus an amino-terminal initiator methionine and glycine. Bacterially expressed PKI has an inhibitory activity identical to that of the protein isolated from rabbit skeletal muscle and, by gel filtration and gel electrophoresis, has the same physicochemical characteristics as the native physiological form of PKI. Fourier transformed infrared spectroscopy and CD establish that PKI has unusually large amounts of random coil and turn structures, with significantly smaller amounts of alpha-helix and beta structures.

Animals↗
PubMed1991

Decreased catalytic subunit mRNA levels and altered catalytic subunit mRNA structure in a cAMP-resistant Chinese hamster ovary cell line.

The mechanisms responsible for decreased levels of cAMP-dependent protein kinase activity in a mutant Chinese hamster ovary cell line have been examined. The cAMP-resistant Chinese hamster ovary 10260 cell line was found to possess only 20% of the cAMP-dependent protein kinase activity found in wild-type cells. The presence of decreased concentrations of the catalytic subunit in these cells was confirmed through binding studies using a radiolabeled, heat-stable inhibitor of the kinase. Cloned Chinese hamster ovary catalytic subunit cDNAs were isolated, characterized, and used as hybridization probes to examine the relative concentrations of catalytic subunit mRNAs in the wild-type and 10260 cell lines. A 40-50% decrease in the concentration of the mRNA for the C alpha isozyme of the catalytic subunit was observed in 10260 cells, as compared with wild-type. This decrease in catalytic subunit mRNA concentration probably accounts for a portion of the decreased kinase activity in the mutant cells. Further analysis of C alpha mRNA by polymerase chain reaction confirmed the decreased expression of C alpha mRNA in 10260 cells and further demonstrated the presence of two different species of C alpha mRNA in the 10260 cells. One species of C alpha cDNAs was indistinguishable from the wild-type cDNA, but the other species was shorter. Nucleotide sequence analysis of the amplified cDNAs led to the identification of a 191-base pair deletion in the shorter cDNA. Gene transfer studies using wild-type and 10260 C alpha cDNAs demonstrated that the longer cDNA from the 10260 cells produced wild-type activity, but the shorter cDNA was inactive. These studies suggest that at least two alterations in gene expression are responsible for decreased cAMP-dependent protein kinase activity in the 10260 cell line. One alteration results in an approximately 2-fold decrease in the concentrations of C alpha mRNA in the cells. The other change produces two species of C alpha mRNA; one of the C alpha mRNAs does not encode an active kinase.

Amino Acid Sequence↗
PubMed1991

Erythrocyte sedimentation rate predicts early relapse and survival in early-stage Hodgkin disease. The EORTC Lymphoma Cooperative Group.

OBJECTIVE: To assess the value of an elevated (greater than 30 mm/h) Westergren erythrocyte sedimentation rate (ESR) for predicting early relapse and survival after therapy in patients with clinical stage I or II Hodgkin disease. INTERVENTIONS: We studied 772 patients with early-stage Hodgkin disease who had participated in two separate multicenter clinical trials. Both trials used modern field radiotherapy and, in some patients, multi-agent chemotherapy. MAIN RESULTS: The ESR patterns were based on pretherapy and post-therapy assessments: pattern 1, always normal (n = 261); pattern 2, elevated before therapy but normal immediately after therapy (n = 121); pattern 3, elevated before therapy but normal within 3 months after therapy (n = 89); pattern 4, always elevated (n = 48); pattern 5, normal before therapy but oscillating between normal and elevated after therapy (n = 150); pattern 6, elevated before therapy but oscillating between normal and elevated after therapy (n = 130). By multivariate analysis, independent of whether or not patients received chemotherapy in the initial therapy protocol, ESR patterns 4, 5, and 6 were shown to be the best predictors for early relapse and survival when patients were stratified according to the type of chemotherapy received and the number of involved nodal areas. Patients with ESR pattern 4 had a relative risk for death seven times that of patients with patterns 1, 2, or 3. Early relapse was the second most important factor predicting death, irrespective of ESR; patients with early relapse and ESR patterns 1, 2, or 3 had a relative risk for death of 4.5, and those with early relapse and ESR patterns 4, 5, or 6 had a relative risk for death of 15. Whether or not chemotherapy was given initially did not change the relative risk, which shows that ESR, not initial therapy, was the predictor for early relapse and death due to Hodgkin disease. CONCLUSION: An unexplained elevated ESR after therapy, especially after modern radiotherapy, independent of other factors, strongly suggest the presence of aggressive and resistant Hodgkin disease. An elevated ESR is predictive of early relapse and poor prognosis; its presence justifies early aggressive therapy.

Adult↗
PubMed1991

Genetic linkage analysis of nerve growth factor (beta) in familial Alzheimer's disease.

Recent studies have not shown linkage of late-onset (mean age, greater than 60 years) familial Alzheimer's disease (FAD) to the chromosome 21 locus reported linked to early-onset FAD. Beta nerve growth factor (beta-NGF) has been considered a candidate gene in the pathogenesis and therapy of FAD, based on its localization in the cortex and hippocampus and its ability to enhance the growth and survival of cholinergic neurons. A 1.5-kb fragment of the beta-NGF gene was used to detect a BglII restriction fragment length polymorphism, which was then used for linkage analysis. A total of 30 families (27 late onset) with 147 affected members were studied. Close linkage (theta less than or equal to 0.03, z less than or equal to -2.00) of late-onset FAD with beta-NGF was excluded. Two apparent obligate crossovers between affected members were detected in different autopsy-confirmed families. Based on these results, beta-NGF is not the gene responsible for late-onset FAD in the families analyzed.

Aged↗
PubMed1991

Translocation (11;14): a cytogenetic anomaly associated with B-cell lymphomas of non-follicle centre cell lineage.

Nine patients with t(11;14) and B non-Hodgkin's lymphomas composed of small to intermediately sized cells with irregular nuclei are described. Immunophenotyping was performed on seven cases, which were M+, D- with light chain restriction, CD5+, CD10-, and CD20+, suggesting that they were non-follicle centre cell lymphomas. The translocation (11;14) (in three cases the only cytogenetic anomaly) was associated with rearrangement of bcl-1 in four of the five cases investigated. Translocation (11;14) has been described in an apparently heterogeneous group of low-grade lymphoid malignancies which we suggest have a non-follicle centre cell lineage in common. This translocation may be associated with these lymphomas in the same way that t(14;18) is associated with follicle centre cell lymphomas.

Adult↗
PubMed1991

Management of relapse and survival in advanced stage Hodgkin's disease: the EORTC experience.

The EORTC Lymphoma Cooperative Group and the Pierre and Marie Curie Group conducted a multicentre randomised trial on clinical stages IIIB-IV Hodgkin's disease from 1981-1986. Two hundred seven patients were registered and 192 randomised. Actuarial survival at five years for the whole group was 68%. Induction chemotherapy with eight cycles of MOPP resulted in more patients with progressive disease and fewer partial responders than a combination of MOPP and ABVD, for an equal complete remission rate. Half of the partial responders went into complete remission after radiotherapy. At five years there was no significant survival difference between the arms. Progression was recorded in 39 patients of whom only 4 survived. Relapses were most frequent in previously involved unirradiated areas. For 46 relapsed patients, including 21 early relapses within 18 months of start of treatment, the four-year survival rate was 53%. When complete remission was reached, whether early or late with combination chemotherapy or after additional radiotherapy, prognosis was independent of the way in which it was achieved. All efforts should be taken to reach a complete remission for initially progressing patients and for partial responders.

Adolescent↗