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At least 127 records · Page 7Linked to original sources
PubMed1976

Studies on complementation of beta hexosaminidase deficiency in human GM2 gangliosidosis.

Complementation of beta hexosaminidase A (hex A) deficiency was obtained by Sendai virus-mediated somatic cell hybridization of cultured skin fibroblasts from two unrelated patients with Tay-Sachs disease (TSD) and one patient with Sandhoff-Jatzkewitz disease (SJD). The newly formed hex A was identified by its electrophoretic mobility in three different systems, heat lability, and reactivity with an antiserum against the unique antigenic determinant, alpha of hex A. The percentage of heterokaryons obtained by virus treatment of TSD and SJD fibroblast mixtures showed good correlation with the observed percentage of hex A activity. It is concluded that, in these two forms of GM2 gangliosidosis, beta hexosaminidase deficiency results from two different mutations. All of the current models of beta hexosaminidase structure are compatible with the observed complementation. No complementation was detected in 13 Sendai virus-induced fusions of cultured skin fibroblasts from seven unrelated patients with SJD. The enzyme deficiency in these patients may be due to very similar allelic mutations, not capable of undergoing complementation; or to different structural mutations, all coding for unstable beta hexosaminidase molecules.

Acetylglucosaminidase↗
PubMed1977

A study of complement fixation by rheumatoid factor using a haemolytic assay system.

Complement fixation by rheumatoid factor (RF) in sera from rheumatoid arthritis patients has been investigated by means of a haemolytic assay system employing sheep erythrocytes (SRBC) coated with reduced and alkylated rabbit IgG anti-SRBC antibody. Haemolysis was almost invariably detected with RF-positive sera whereas haemolysis was not observed with RF-negative sera; It was evident from a marked increase in haemolysis, obtained following isolation of IgM-RF of high purity from several RF-positive sera, that the full in vitro complement-fixing ability and hence lytic potential of RF in serum is masked. Parallel observations were also made with synovial fluids. The inhibition of haemolysis by RF in sera and synovial fluids commonly involved a reduction in degree of lysis at high concentration of test material as well as a more generalized inhibition in overall percentage lysis. Complete replication of typical RF-positive serum and synovial fluid patterns of lysis on dilution was achieved by addition of heat-aggregated human IgG to isolated IgM-RF preparations and demonstrated that the two inhibitory effects are separable in terms of complement depletion and reduction of free rheumatoid factor antibody activity, respectively.

Arthritis, Rheumatoid↗
PubMed1988

Action of a new non-steroid antiinflammatory drug, nimesulide, on activation of the complement system: an in vitro study.

The complement system has a pivotal role in the antiinflammatory reaction. Furthermore it has been shown that the sequential activation of the complement system may be inhibited at various levels by pharmacological agents such as non-steroidal antiinflammatory drugs. Therefore the eventual anticomplementary action of Nimesulide was assessed in vitro in various experimental models. It was found that it blocks immunohaemolysis in vitro and has a direct effect on serum complement activity. Nimesulide blocks the activation of third complement and this explains why the drug is also inhibitory on the inulin-induced haemolytic reaction.

Animals↗
PubMed1989

Paediatric coeliac disease and dermatitis herpetiformis: differences in complement activation in relation to diet.

We studied complement (C') involvement in paediatric coeliac disease (CD) and dermatitis herpetiformis (DH) in relation to lesions and function of enteric mucosa and to diet. For this purpose, 50 children affected by CD and 42 affected by DH were subdivided in 3 groups: in the first (I) were included subjects in free diet, in the second (II) children during gluten-free diet (GFD) and in the third (III) subjects after gluten reintroduction in diet. Only in CD we found significant modifications of some C' parameters. In fact C3 and C4 levels increase in II group in GFD (respectively p less than 0.02 and p less than 0.03) and result inversely correlated to an arbitrary score for the evaluation of the enteric histological lesions (p less than 0.02 and p less than 0.01). C3d/C3 ratio levels, as catabolic index of C3, result always greater than normal in both diseases, but significantly decrease only in II group of CD children (p less than 0.02), where they result also positively correlated to the histological score (p less than 0.05). Circulating immune complex-like material is higher in DH, but incidence of pathological values decrease in II group only in CD (p less than 0.04). These data suggest probable significant differences in the pathogenetic mechanisms of CD and DH involving C'.

Antigen-Antibody Complex↗
PubMed1986

Clinical heterogeneity in cobalamin C variant of combined homocystinuria and methylmalonic aciduria.

We describe two patients with methylmalonic aciduria and homocystinuria (Cbl C). The disorder was not diagnosed in patient 1 until 4 1/2 years of age; he had a history of fatigue, anorexia, delirium, and spasticity. Moderate megaloblastic bone marrow changes were observed, and there was hyperreflexia of the lower limbs. His condition improved clinically with hydroxycobalamin therapy. Patient 2 was hospitalized at 6 weeks of age because of lethargy and poor feeding. She was found to have macrocytosis. Despite an initial good clinical response to hydroxycobalamin, she developed a striking pigmentary retinopathy. Methylmalonic aciduria persisted in both patients, and homocystinuria persisted in patient 1 despite therapy. The diagnosis of Cbl C disease has been confirmed in both patients by biochemical studies of cultured fibroblasts, including complementation studies. The differences in age of onset and clinical findings together with the similar biochemical findings in these two patients demonstrate the heterogeneity of phenotypic expression in patients with apparently identical abnormalities of vitamin B12 metabolism.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

Absence of RT6+ T cells in diabetes-prone biobreeding/Worcester rats is due to genetic and cell developmental defects.

Diabetes-prone BB/Wor (DP) rats lack the RT6+ peripheral T cell subset whereas diabetes-resistant BB/Wor rats have normal numbers of RT6+ T cells. Lymphocyte transfusion experiments and in vivo depletion studies have demonstrated that RT6+ T cells have an important regulatory role in the pathogenesis of insulin-dependent diabetes mellitus in BB/Wor rats. In the present study, the results of genetic complementation studies indicate that the DP rat contains an intact RT6 gene, but fails to express the RT6.1 alloantigen in the functional absence of an accessory factor (provided by RT6+ cells). At the cellular level, irradiation chimeras demonstrate that the absence of RT6+ T cells in DP rats is due to an intrinsic defect that results in abnormal development and/or differentiation of prothymocytes into RT6+ T cells. The inability of DP prothymocytes to generate RT6+ T cells is not due to serum autoantibodies, lack of accessory cells, or to the presence of inhibitory cells. Inasmuch as DP bone marrow can transfer the susceptibility for diabetes to irradiated recipients, our present results suggest that an important predisposing factor for insulin-dependent diabetes mellitus in DP rats is the inability of DP prothymocytes to generate RT6+ T cells.

Animals↗
PubMed1989

Analysis of the chromosome complement in outbred mouse sperm fertilizing in vitro.

The chromosome complements in a population of mouse sperm from random-bred ICR donors were analyzed at first-cleavage metaphase after in vitro fertilization (IVF) of oocytes from females of the same strain. The sperm were aged as donations occurred within an average of 31 days, either since last mating or at arrival at the animal facility in the case of virgin males. Of a total of 598 sperm complements studied from 22 sexually mature males aged 10-26 weeks old, there was one diploid complement (0.17%). The frequencies of hyperhaploidy and structural aberrations that were studied in 338 complements were 4.4% and 3.6%, respectively, giving an overall frequency of 8.0%. The hyperhaploid complements consisted of n + 1, n + 2, n + 3, and n + 7 counts, while the structural abnormalities were of the chromosome type and included large and small fragments and a possible translocation. This is the highest frequency of sperm chromosome abnormalities reported for mouse sperm obtained from males under physiological conditions and fertilized in vitro or in vivo. Sperm aging, strain, and/or technique differences are among the factors that may be responsible for this high frequency. Since the 8.0% frequency of hyperhaploidy and structural abnormalities is similar to the frequency reported for human sperm after IVF, the outbred murine in vitro fertilization system may be a useful model to study the origin of human sperm chromosome abnormalities.

Aneuploidy↗
PubMed1992

Effect of BSO on the radiation response at low (0-4 Gy) doses.

Depletion of thiols by various agents has been shown to radiosensitize hypoxic cells. The agent BSO is used to specifically inhibit GSH synthesis, and the effect of this treatment on radiation response, particularly in the region of clinical interest, was studied using automated microscopic identification of cells for measurement of high survival levels. In both CHO and V79 cell lines, the enhancement rations were greater at low doses (80% S) than at high doses (2% S) in cells irradiated in hypoxia. GSH depletion also affected the aerobic response in both dose regions, with again higher ER's observed at low doses. These results support previous studies which suggest that GSH levels affect the shoulder portion of the survival curve. However, as with untreated cells, the OER's remain higher at high doses than at low doses, in BSO treated cells of both lines. These studies complement an earlier low-dose study on diamide by Skarsgard and co-workers, and were carried out to increase our understanding of the factors which affect radiation sensitivity in the range of doses used in fractionated regimens in the clinic.

Animals↗
PubMed1991

In vitro activation of human complement by nitrogen bubbles.

Complement activation may be responsible for some of the symptoms of decompression sickness. In the present study, complement activation was studied by exposing human sera with or without red blood cells to nitrogen bubbles. Nitrogen bubbles activated human complement as measured by generation of the fluid-phase, complement-split product C5a des Arg. In addition, we found that complement activation continued after exposure to bubbles was stopped. This continued complement activation may explain the failure of recompression treatment in some patients. Complement activation induced by nitrogen bubbles in human sera was enhanced when red cells were present. Red cells may be able to provide a stable membrane surface on which complement activation by bubbles can occur more efficiently. Complement activation by nitrogen bubbles in serum also led to the binding of activated C3 to red cells. Quantitation of bystander red-cell-bound C3d may allow the assessment of complement activation occurring by nitrogen bubbles in individuals undergoing decompression.

Complement Activation↗
PubMed1991

Type C Niemann-Pick disease: biochemical aspects and phenotypic heterogeneity.

Within Niemann-Pick diseases, type C has now been demonstrated to be a nosological entity totally distinct from types A and B, and is best characterized at present by unique abnormalities of intracellular translocation of exogenous cholesterol, which are briefly reviewed. Although the primary defect is still unknown in type C Niemann-Pick disease, this discovery has had immediate medical applications, by providing the first strategy for reliable prenatal detection of the disorder and easy diagnosis of patients. From our personal experience of 134 cases, diagnosis is best reached by the combined demonstration of a deficient induction of esterification and of an intravesicular cholesterol storage by cytochemistry after filipin staining. The prevalence of the various clinical forms observed is given, together with a brief report of 6 adult-onset cases. The spectrum of phenotypic heterogeneity in relation to abnormal LDL processing has been defined, resulting in the delineation of three biochemical groups, classical (86%), variant (7%) and intermediate (7%). Correlations between clinical and biochemical phenotypes have been studied. To get further insight into genetic heterogeneity, complementation studies were performed. Preliminary results have yet given no evidence of several complementation groups within type C Niemann-Pick disease. The recognition of the three biochemical phenotypes is however critical for diagnosis and genetic counselling.

Adolescent↗
PubMed1988

Abdominal aortic aneurysm.

Between 1981 and 1986, 282 cases of abdominal aortic aneurysm were diagnosed in Waltham Forest. Rupture had occurred in 183, 15 underwent urgent operation for intact aneurysm, and 84 had elective surgery. The incidence of rupture increased from 13 to 21 per 100,000 population during the 6-year period. Operative mortality for patients with rupture was 54.7 per cent, but the mortality overall was 81.4 per cent. In 59 per cent of patients with rupture no operation was performed, and 35.0 per cent of all deaths occurred in the community. The mortality for rupture in women was significantly higher than in men, although the operative mortality was comparable. Fifty patients (27 per cent) were found to have attended hospital within 2 years of rupture and many had documented evidence of an aneurysm. One-third of all patients admitted with rupture were undiagnosed. This study complements the previous small number of community studies and suggests that the incidence of rupture is increasing nationally particularly in women, where the mortality was exceptionally high. Early elective surgery is the key to the problem and improved clinical awareness could save many patients without elaborate and expensive programmes to screen the 'at risk' population.

Age Factors↗