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Biomedical subjects

M Joseph

Publications and source records attributed to M Joseph.

252 records · Page 14Linked to original sources
PubMedDate not supplied

The effector function of platelets is induced and regulated by T lymphocytes.

The demonstration of effector functions of platelets in parasitic diseases raised the question of their possible regulation by T lymphocytes. Normal human platelets, treated with culture supernatants from antigen- or mitogen-stimulated CD4+/CD8- T cells, developed the capacity to kill young larvae of Schistosoma mansoni, in the absence of antibodies. The presence of IFN gamma in the lymphocyte supernatants, the neutralization by monoclonal anti-IFN gamma antibody, and the direct inducer effect of recombinant IFN gamma, clearly identify this lymphokine as one of the stimulator factors. In contrast, ConA- and antigen-stimulated human CD8+/CD4- T-cell supernatants contained a factor able to inhibit the IgE-dependent platelet cytotoxicity toward the same targets. The production of oxygen metabolites by IgE-coated platelets stimulated by anti-IgE was also strongly inhibited by this lymphokine. This platelet activity suppressive lymphokine (PASL) was identified as a polypeptide of 15 to 20 Kd with a pI of 4.6. The in vivo relevance of PASL was demonstrated by the complete abolition, after PASL treatment, of the protection normally conferred following a challenge infection by intravenous passive transfer of platelets from immune to normal rats.

Adult↗
PubMedDate not supplied

Expression of active human factor IX in transfected cells.

Factor IX is the precursor of a serine protease that functions in the intrinsic blood clotting pathway. Deficiencies in this plasma glycoprotein result in haemophilia B (or Christmas disease) and occur in about 1 in 30,000 males. Patients are currently treated with fresh frozen plasma or prothrombin complex concentrates prepared from pooled plasma from normal individuals. There are several problems with this method of treatment, including the probable exposure of the patients to contaminants such as the viral agents responsible for hepatitis and AIDS (acquired immune deficiency syndrome). As a first step towards an alternative source of pure human factor IX, we report here on the use of recombinant DNA techniques to produce biologically active factor IX in cultured mammalian cells. Stable cell lines were produced by cotransfecting a baby hamster kidney (BHK) cell line with a plasmid containing a gene for factor IX and a plasmid containing a selectable marker. Protein secreted by these cell lines reduces the clotting time of plasma from factor IX-deficient patients. We present additional evidence that this protein is authentic human factor IX.

Animals↗
PubMedDate not supplied

Platelets mediate the action of diethylcarbamazine on microfilariae.

More than 400 million people in the world are infected by filarial parasites leading to a wide range of pathologies. Although introduced in 1947, the mainstay of the therapy and control of the filariases is diethylcarbamazine (N,N-diethyl-4-methyl-1-piperazine carboxamide; DEC), the mode of action of which still remains unknown despite widespread use and intensive laboratory investigations. The marked contrast between an extremely rapid action in vivo and the absence of any significant activity on microfilariae in vitro is unique among chemotherapeutic agents. DEC has been thought to modify the surface layer of the microfilariae and expose them to immunological cell-mediated lysis. This report provides the first evidence that the effect of DEC is mediated by blood platelets with the additional triggering of a filarial excretory antigen (FEA). The killing mechanism is antibody-independent and involves the participation of free radicals.

Animals↗
PubMedDate not supplied

Pathologic-spontaneous-rupture of the spleen as a presenting sign of splenic T-cell lymphoma--case report with review.

A 39 year-old man presented for surgery with epigastric pain, tachycardia, hypotension and a progressive decrease of hemoglobin due to blood loss. Immediate abdominal ultrasonography followed by prompt paracentesis revealed massive intraperitoneal hemorrhage. During emergency laparotomy, a linear, actively bleeding rupture of an enlarged spleen was found and splenectomy was performed. The patient survived and the post-operative course was uneventful. Histopathology of the spleen as well as bone marrow biopsy confirmed the diagnosis of T-Cell lymphoma. Chemotherapy was initiated 3 weeks after surgery. To the best of our knowledge, this is the first reported case of previously undiagnosed T-Cell lymphoma presenting as pathologic rupture of the spleen.

Biopsy↗
PubMedDate not supplied

The SAPHO syndrome in children: a rare cause of hyperostosis and osteitis.

The SAPHO syndrome is a rare constellation of signs and symptoms characterized by synovitis, acne, pustulosis, hyperostosis, and osteitis. The most common musculoskeletal complaints are hyperostosis, causing pain, tenderness, and swelling of the anterior chest wall, although any part of the axial and appendicular skeleton may be affected. There is a great degree of variability in the dermatologic involvement of this syndrome. A combination of clinical, radiographic, and pathological investigation is required to establish the correct diagnosis. No single treatment has been found to be effective, although nonsteroidal antiinflammatory drugs have been the most frequently used. Because there is no mention of SAPHO syndrome in the English orthopaedic literature, and pediatric orthopaedic surgeons may be the first caregivers to treat these children, we thought it appropriate to share our experience with a 5-year-old boy with SAPHO syndrome recently under our care.

Acquired Hyperostosis Syndrome↗
PubMedDate not supplied

Comparative evaluation of effect of auxiliary retentive features on retention of complete cast crowns in teeth with adequate and inadequate crown height. An invitro study.

This study was done to evaluate the retention of complete cast crowns in teeth with adequate and inadequate crown height and to evaluate the effects of auxiliary retentive features on retention from of complete cast crowns. Thirty-six extracted human maxillary first premolars were obtained. In one group teeth were prepared to a constant height of 3.5 mm and in the second group teeth were prepared to a constant height of 2.5 mm. Each group was further subgrouped into three. In the first subgroup teeth were prepared conventionally, second subgroup proximal grooves were incorporated and in the third subgroup proximal boxes were incorporated. Tensional forces required to dislodge each cemented casting from its preparation was used for comparison of retention quality. These results were then subjected to an analysis of variance (ANOVA). The retention of crown in tooth with adequate crown height were statistically highly significant (P < 0001), compared to inadequate crown height and in boxes compared to grooves and conventional preparation.

Analysis of Variance↗
PubMedDate not supplied

Comparative evaluation of the effect of simulated porcelain firing cycle on the mechanical properties and microstructure of base metal ceramic alloys.

A comparison of mechanical properties and microstructure of four metal ceramic alloys in as-cast and heat-treated conditions resulted in significant differences. The alloys that were tested included two nickel-based and two cobalt-based metal ceramic alloys. Mechanical properties tested included strength, percent elongation and hardness. Ten tensile bars were cast for each alloy. Five of the ten bars for each alloy were randomly selected for heat treatment with the simulated porcelain firing cycle. Results indicated that the nickel-based alloys were weakened by the heat treatment and showed a decreased hardness and an increased elongation. The effects of heat treatment on the strength of cobalt-based alloys were variable, showing an increase in hardness and a decrease in elongation. Differences in mechanical properties exhibited by the alloys were related to compositional and microstructural changes.

Analysis of Variance↗
PubMedDate not supplied

Stress variations in recast Ni-Cr alloy--a finite element analysis.

A finite element analysis was carried out to analyse the stress variations in a mandibular posterior fixed partial denture (FPD), made of recast nickel-chromium alloy. A two dimensional finite element model was developed and then analysed with STAAD III/ISDS program with an occlusal load of 1 kg applied to the casting surface. The analysis revealed that the connectors experienced maximum stresses and the generated stress values decreased within the fixed partial denture made of recast Ni-Cr alloy. It seemed unlikely that FPD inspite of being made of recast alloy might fail before the other tissue components show signs of degeneration thus establishing the potential for recycling the Ni-Cr alloy in actual dental practice.

Bite Force↗
PubMedDate not supplied

Comparative evaluation of tensile bond strength of denture base resins to surface pretreated cobalt chromium base metal alloys--an in vitro study.

This study was undertaken to evaluate the tensile bond strength of acrylic resins to surface pretreated Cobalt-chromium base metal alloy. A total of 60 tensile bar specimens were prepared. One half of the bar was cast in cobalt-chromium alloy and the other half made of denture base resins attached to the alloy following surface pretreatment. Two denture base resins and five surface pre-treatments were used which included sandblasting, acid etching, use of metal adhesive primers and the combination of the above mentioned modes. Gradual axial loads were applied on the tensile bar specimen mounted on a Hounsfield tensometer till bond failure was evident. Statistical evaluation was done using Mann-Whitney U test. The study results indicate that the bond strength in those specimens wherein a combination of sandblasting, acid etching and priming was done as surface pretreatment, showed the maximum values as compared to the other groups.

Acid Etching, Dental↗
PubMedDate not supplied

Ambient noise strategy: a solution for noise control?

The British Government earlier this year undertook a consultation on its proposal, announced in the Rural White Paper, to develop an Ambient Noise Strategy in England. The proposals envisage a three phase approach: In phase 1 we would aim to establish three key sets of information: information on the ambient noise climate in the country--i.e. the number of people affected by different levels of noise, the source of that noise (road, rail, airports and industry) and the location of the people affected, by producing noise maps of the main sources of noise; methods which the Government might use to assess the effects of noise--particularly regarding people's quality of life and tranquility; the techniques available to take action to improve the situation where bad or preserve it where good. In phase 2 we would aim to evaluate and identify options for prioritising the various alternatives from phase 1 in terms not only of costs and benefits but also time-scales and synergies and conflicts with other Government priorities including economic and social issues. An optimal policy reduces noise at lowest net cost, whilst capturing as many synergistic benefits, and minimising any potentially adverse impacts. Decision makers need to ensure that the impacts of the noise policies do not cost society more than the benefits expected. A recent study undertaken by the Government, looked at how a cost-benefit type framework could be used, with noise maps, to help inform such decisions. Finally, in phase 3, the Government would need to agree on the necessary policies to move towards the desired outcome--i.e. the National Ambient Noise Strategy itself. The results of the consultation are expected to be published later this year.

Databases, Factual↗
PubMedDate not supplied

A pilot study of the prevalence of herpes genitalis among selected groups of patients seeking care in a family practice center.

Herpes genitalis is typically studied in patient panels identified at specialized sexually transmitted disease clinics or with information obtained from herpes self-help groups. This article reports the results of a descriptive pilot study of the prevalence of herpes genitalis in family practice. The feasibility of obtaining psychosexual information on sexually transmitted diseases from more than 600 patients from five family practice practices was assessed. These initial data show that in the family practices participating in this study: 1) genital herpes is a low prevalence disease; 2) psychosocial adjustment to the disease among infected persons is usually reported as good, apart from sexual effects; and 3) close to 30% of the study population reported having prior sexually transmitted diseases. Problems involved in generalizing the results of this research and the limitations of conducting collaborative clinical research in family practice settings are reviewed.

Activities of Daily Living↗
PubMedDate not supplied

Antigenic release of paf-acether and beta-glucuronidase from alveolar macrophages of asthmatics.

Alveolar macrophages (AM) from control (n = 12) and atopic patients (n = 19, 12 without treatment, 4 treated with theophylline and 3 with theophylline and corticosteroid) were compared for their capacity to release mediators. AM were purified by 2 h adherence and challenged with either ubiquitous allergen, specific sensitizing allergens, anti-IgG or anti-IgE serum. The release of paf-acether, lyso paf-acether and beta-glucuronidase was measured. Paf-acether and its lyso derivative were assayed on washed rabbit platelets. Enzyme and mediator releases were obtained after specific allergenic or anti-IgE serum challenge of AM from untreated atopic patients. No release of paf-acether was detected from AM, from control or treated atopic patients after in vitro immunological challenge, whereas that of lyso paf-acether was greatly reduced in both treated groups. Release was obtained by immunological challenge of AM from control patients after passive sensitization with atopic serum. The release of mediators with bronchoconstriction activity by AM could represent an alternative causal pathway in human asthma.

Adult↗
PubMedDate not supplied

The beta-glucuronidase release from macrophages activated by immune complexes of varying antigen/antibody ratio.

When unstimulated rat peritoneal macrophages are exposed in vitro to IC formed with BSA and specific rat anti-BSA IgG antibodies, an exocytosis of the lysosomal beta-G occurs. The maximal release of beta-G into the serum-free medium is induced, without cell lysis, by IC after a 6-h contact with the adherent cell population. This phenomenon is dose-dependent, and the percentage of beta-G in the medium is higher with IC in Ab excess than with other types of IC. In this homologous model (rat macrophages and rat antibodies) the Ag/Ab ratio of IC seems to represent an important factor of macrophage activation.

Animals↗
PubMedDate not supplied

Is the role of fatty acids only to provide membrane-anchor in fatty acylated proteins?

A large number of proteins on the eukaryotic cell surface that play an important role in cellular metabolism are covalently modified with fatty acids like palmitic and myristic acids. While some of these proteins have transmembrane spanning segments, many others do not. Early hypothesis was that this co or posttranslational modification helped in membrane-association and the fatty acyl chain provided a stable membrane anchor. We have investigated the structure of peptides with these modifications and also their interaction with membranes. Our results indicate that the fatty acylated peptides, especially when the peptide segment is not hydrophobic, do not have strong affinity for membranes. The recent observations about the dynamic nature of fatty acid acylation as well as the importance of protein-protein interactions for function in fatty-acylated proteins suggest that membrane-association may involve factors other than only the fatty acid, either myristic or palmitic. Revised models depicting the possible role of fatty acids in modulating protein-protein interaction and their dynamics is presented.

Acylation↗