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Biomedical subjects

A Weiss

Publications and source records attributed to A Weiss.

At least 253 records · Page 14Linked to original sources
PubMed1990

Growth and differentiation of murine cartilage cells in vitro following a short-term exposure to triamcinolone acetonide.

Measurements of 3H-thymidine incorporation, quantitative autoradiography and morphometry were used to evaluate cell behavior during the recovery of mandibular condylar cartilage cultures following short-term exposure to a corticosteroid hormone in vitro. Apical segments of mandibular condyles of newborn mice were initially incubated in the presence of the hormone triamcinolone acetonide (10(-6) M) for 24 h and were thereafter cultured for additional 6 days in hormone-free medium. The present results indicated that the treatment led to a decrease in the rate of incorporation of 3H-thymidine, a feature that lasted for 48 h following the removal of the hormone. Quantitative 3H-thymidine autoradiography of explants that were labeled in the presence of the hormone further substantiated the initial suppressive effect of the hormone on cellular proliferation, a feature that was followed by a recovery. Differences were noted in the pattern of distribution of labeled cells: in control explants, labeled cells progressively moved from the chondroprogenitor compartment into the differentiated portion of the cartilage; in hormone-treated explants, 3H-thymidine labeled cells were confined to the progenitor layer up to 5 days after the treatment and only then appeared in the chondrocytic compartment. The hormone's adverse effect upon differentiation was manifested by both morphology, and by causing a significant increase in the size of the progenitor layer (up to 50.5% on 4th post-treatment day) along with a 70.5% reduction in the size of chondroblastic layer. We conclude that a short-term exposure to a glucocorticoid hormone in vitro interferes with proliferation of chondroprogenitor cells and their subsequent differentiative pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A transfected human muscarinic receptor fails to substitute for the T cell antigen receptor complex in CD2-initiated signal transduction.

Several T cell surface molecules can activate signal transduction pathways that lead to T cell activation. Like the T cell antigen receptor (TCR), several other molecules, including the sheep erythrocyte receptor CD2, are able to activate the phosphatidylinositol (PI) signal transduction pathway upon stimulation with appropriate agonists. However, CD2-initiated activation of this pathway is dependent on the functional expression of the TCR. Since the T cell does not express other known receptors that activate the PI pathway independent of the TCR, the specificity of the CD2 requirement for a functional TCR is not known. To evaluate the specificity of this requirement, we examined the functional capacity of CD2 to activate the PI pathway in a TCR-deficient cell which had been transfected with a heterologous receptor, the human muscarinic subtype 1 receptor (HM1). HM1 is a member of the cholinergic family of receptors and is known to activate the PI pathway. HM1 can function in the absence of the TCR in a Jurkat-derived T cell host. Here we demonstrate through calcium fluorimetry and PI metabolism assays that HM1 is unable to substitute functionally for the TCR in CD2-initiated signal transduction. These results suggest a specific functional interaction between CD2 and the TCR in CD2-mediated activation of the PI pathway in T cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Changes in growth patterns in mouse condylar cartilage associated with skeletal maturation and senescence.

The squamoso-mandibular joint (SMJ) represents one of the most active joints in the mouse. In the young animal the main function of condylar cartilage in the SMJ is to serve as a growth center for the developing mandible. This first phase of skeletal growth lasts up to the age of 6-8 weeks, and is manifested by appositional growth of cartilage followed by endochondral ossification. Thereafter, the condylar cartilage gradually changes its function and serves mainly as an articulating surface for the joint. Consequently, the cartilage changes from a calcifying hyaline cartilage to a fibrous non-calcifying cartilage. The latter phase lasts through the stage of maturation (6 months of age) and it is manifested by a combination of appositional and interstitial patterns of cellular growth. Thereafter, the third phase develops which is characterized by degenerative changes that typify the aging process. In vivo autoradiography with [3H]-thymidine indicated that in the very young animal labeled cells are confined to the chondroprogenitor (proliferative) zone of the condylar cartilage. With maturation, the dimension of this zone as well as the number of labeled cells decrease, so that by 3 months of age the labeling index decreases by 30%. By the age of 6, 12 and 18 months, almost no cells take up the radioisotope while the total number of cells declines. During senescence only a very limited interstitial growth is taking place, a feature that might be associated with the repair processes that accompany the onset of osteoarthritic lesions.

Aging↗
PubMed1990

[The state of professional psychological guidance for patients with multiple sclerosis].

Over a period of two years, a total of 847 patients with multiple sclerosis (283 male and 564 female aged 18 to 79 years) were interviewed relative to the psychological care provided. Two patients currently participated in regular client-centered group therapy, 11 patients had regularly attended individual or group psychotherapy in previous years, and one patient had undergone family therapy several years ago. Another 26 patients reported occasional supportive counselling by their neurologist or family doctor in the framework of outpatient care. Ten patients used relaxation techniques such as autogenic training, and 42 patients reported emotional benefit from contacts within an MS self-help group. The findings of our study show that professional psychological care of persons with MS is extremely sparse, substantiating the call for better psychological services in coping with MS.

Adaptation, Psychological↗
PubMed1990

[A new computer-controlled device for stress images of the upper ankle joint].

A new apparatus has been developed for stress roentgenograms of the ankle joint to demonstrate rupture of the fibular collateral ligaments possible. The disadvantages of well-known techniques, such as manual application of stress and the use of holding devices are eliminated. The inversion stress is applied by a foot support driven by an electric motor. A microcomputer controls the force of inversion in dependence on reactive muscle splinting; i.e. the apparatus simulates the application of the inversion force by a physician acting according to feeling. In contrast to the radiography technique with manual holding, the patient is not able to press the foot against the inversion force if a pain-reflexive muscle contraction occurs. Other holding devices generate the inversion force with a threaded shank or traction weight; with the new device the patient's discomfort lasts only 2 s. In the last 5 years the new holding device has shown its reliability in about 1500 examinations.

Ankle Injuries↗
PubMed1989

Urinary leukocyte esterase screening test for asymptomatic chlamydial and gonococcal infections in males.

We evaluated the ability of the urinary leukocyte esterase test to predict culture-verified chlamydial and gonococcal urethritis among asymptomatic adolescent males. Nine hundred forty-eight sexually active males provided first-catch urine samples for esterase screening, and 76 (8%) tested positive (greater than or equal to 1+). Among 435 boys who agreed to undergo urethral culture, the esterase was positive in 66 (15%), Chlamydia trachomatis was isolated from 39 (9%), and Neisseria gonorrhoeae was isolated from 14 (3%). The sensitivity, specificity, and positive and negative predictive values for the esterase test were 72%, 93%, and 58% and 96%, respectively. Using the esterase test to screen asymptomatic males for urethritis, we identified 38 culture-verified infections that otherwise would have remained undetected. The urinary leukocyte esterase test is a noninvasive and cost-effective screening method to detect urethritis among asymptomatic adolescent males.

Adolescent↗
PubMed1989

Function of a heterologous muscarinic receptor in T cell antigen receptor signal transduction mutants.

Previously we have described a system of somatic cell genetics (J.CaM1 and J.CaM2) for analyzing signal transduction via the T cell antigen receptor complex (CD3/Ti). Here we describe a third mutant, J.CaM3, which also expresses high levels of receptors that are functionally impaired. Like J.CaM1, J.CaM3 demonstrates partial signal transduction via CD3/Ti to only certain stimuli. J.CaM1, J.CaM2, and J.CaM3 define three non-Ti complementation groups involved in receptor function. To evaluate the mutations further we have introduced a heterologous receptor, the human muscarinic receptor 1 (HM1), into the parental Jurkat and mutant cell lines. This receptor demonstrates signal transduction competence in all these hosts, indicating that 1) T cells express the necessary apparatus for the coupling of HM1 to second messenger generation and 2) the mutations in the J.CaM family all affect molecules that are specific to CD3/Ti, and not HM1, function. Finally, the HM1 receptor exhibits partial sensitivity to cholera toxin in Jurkat cells, in contrast to the virtually complete sensitivity of CD3/Ti to cholera toxin.

Antibodies, Monoclonal↗
PubMed1989

Heterogeneity of protein kinase C isoenzyme gene expression in human T cell lines. Protein kinase C-beta is not required for several T cell functions.

An early consequence of stimulation of T cells via their Ag receptor is the activation of protein kinase C (PKC). It has recently been shown that PKC activity resides in a family of homologous proteins. Inasmuch as T cells are phenotypically and functionally heterogeneous, we examined the possibility that this heterogeneity may be reflected in differential expression of message for PKC isoenzyme genes. RNA from six leukemic T cell lines was probed for PKC-alpha, -beta, and -gamma message before and after activation. These studies revealed significant differences among these lines. None expressed mRNA for PKC-gamma. Whereas all cells possessed message for PKC-alpha, there was consistent variability in the level expressed. The greatest heterogeneity was seen with PKC-beta. Two cell lines, HUT 78 and HPB-ALL, did not hybridize with the beta probe under any conditions tested. We subsequently used these PKC-beta negative cells to study the role of this isoenzyme in mediating some of the effects seen with phorbol esters that directly bind to and activate PKC. Our results indicate that PKC-beta, which is expressed in some T cells, is not necessary for PMA-induced CD3 or CD4 internalization, IL-2 production, or acquisition of the p55 chain of the IL-2 receptor.

Cell Line↗
PubMed1989

Articular chondrocytes lose their proliferative activity with aging yet can be restimulated by PTH-(1-84), PGE1, and dexamethasone.

Mouse mandibular condyles develop spontaneous degenerative changes by 6 months of age, hence providing a good in vivo model for studies related to processes associated with the onset and progression of age-related osteoarthritis. Further, this joint provides an appropriate system to investigate the potential of articular cartilage to respond to hormones and local growth factors in old age. The present study examined (1) the age-related changes in [3H]thymidine incorporation by articular chondrocytes in the mouse mandibular condyle, and (2) the effect of systemic and local factors upon the tissue's ability to resume DNA synthesis. Condyles of female CW-1 mice ranging from 3 to 18 months of age were cultured in the presence of PTH-(1-84) (2 micrograms/ml), PGE1 (20 micrograms/ml), dexamethasone (10(-7) M), and MSA (5 micrograms/ml) and were concomitantly labeled with [3H]thymidine. Autoradiographs were analyzed quantitatively and revealed (1) a significant (p less than 0.01) age-related decrease (-80%) in the labeling index of the articular cartilage, and (2) the ability of old tissues to resume DNA synthesis following in vitro treatment with PTH-(1-84), PGE1, and dexamethasone. Concomitant quantitative incorporation studies further substantiated the autoradiographic findings. Hence, these factors possess a direct stimulatory effect upon senescent chondrocytes involved in an advanced stage of spontaneous osteoarthritis.

Aging↗
PubMed1989

Biliverdin reductase activity in cattle, sheep, rabbits and rats.

1. Biliverdin reductase (BVR) activity was measured in post-microsomal supernatants of livers of cattle, sheep, rabbits and rats. BVR activities in bovine and ovine livers were 4.7 and 5.0%, respectively, of rat liver activity. 2. The finding of BVR activity in ruminants is in contrast to a previous report and may be due to the use of a different assay system. 3. Lapine liver had the lowest BVR activity of only 0.37% of rat liver activity. 4. Increasing the available heme by phenylhydrazine administration did not induce increased hepatic or splenic BVR activity in rabbits. 5. Maximal BVR activities were attained using NADPH as cofactor at pH 8.7 in sheep and rabbits and at pH 8.4 in cattle. 6. Differing concentrations of bovine or human albumins enhanced or inhibited BVR activity quite differently in the various species. 7. The finding of a very low, but measurable BVR activity in lapine liver and spleen may explain, in part, why rabbits, unlike rats, cattle and sheep, excrete primarily biliverdin (70%) into bile.

Anemia, Hemolytic↗
PubMed1989

Ph-negative T cells in a patient with chronic myelogenous leukemia for twenty-eight years.

The frequency of metaphases without a Philadelphia chromosome was determined in mitogen-stimulated cultures of peripheral blood mononuclear cells (PBMC) and purified T lymphocytes (93% CD2-positive) from a patient with chronic myelogenous leukemia (CML) for 28 years. The PBMC cultures contained few Ph-negative cells (8%), but they constituted 92% of the metaphases in T cell cultures, indicating few if any Ph-positive T cells in the patient's circulation. The results demonstrate that T cells derived from the leukemic clone may fail to replace the non-neoplastic population even when CML arises in childhood and the patient survives for many years. This raises questions concerning the normal role of the bone marrow as a source of T cells after infancy, and also whether Ph-positive lymphocytes may be at a disadvantage for growth.

Adult↗