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Biomedical subjects

M Beck

Publications and source records attributed to M Beck.

At least 19 recordsLinked to original sources
PubMed1992

Deletion of the Hunter gene and both DXS466 and DXS304 in a patient with mucopolysaccharidosis type II.

Hunter syndrome is an X-linked mucopolysaccharidosis due to deficiency of the lysosomal enzyme iduronate-2-sulfatase (IDS). A cDNA clone containing the entire coding region of the human IDS gene, mapped in Xq28, has been used as molecular probe to study a patient with Hunter syndrome. A submicroscopic deletion has been detected that spans the IDS gene as well as DXS466 and DXS304, 2 loci mapped probably not more than 900 kb from the IDS locus. A detailed clinical description of the patient is provided and his phenotype is compared to that of other patients with IDS deletion described recently. By following the segregation of a restriction fragment length polymorphism at the IDS locus in the patient's family, our data suggest that the deletion occurred in the germ cells of the patient's grandfather.

Blotting, Southern↗
PubMed1992

Influence of retinol on human chondrocytes in agarose culture.

Vitamin A and its congeners, collectively called retinoids, are known to have teratogenic potential and have induced craniofacial and limb malformations in numerous animal species. More importantly, retinoids are recognized as teratogenic to fetuses of pregnant women who have taken such preparations for dermatologic disorders. Information gathered from the study of animal models suggests that retinoids interfere with cartilage differentiation. If chondrogenesis in limb development is disturbed it may contribute to limb reductions and malformations. In vitro studies using various animal systems have shown that cartilage matrix macromolecules are altered to resemble those secreted by mesenchymal cells. The response of human chondrocytes to retinoids in vitro is not known. Culture of human chondrocytes in agarose maintains the cartilage phenotype and therefore serves as a model system to evaluate the influence of retinoids directly on human chondrogenesis. The studies presented in this paper were done to determine if the expression of specific matrix macromolecules of human chondrocytes in agarose culture is altered by retinol treatment. Immunocytochemistry demonstrated enhanced labeling of type I collagen while type II collagen labeling was reduced in cultures treated with retinol. In addition, morphometric analyses indicated a decrease in the size and number of chondrogenic clusters and that individual cells synthesized less alcian blue matrix when compared to parallel control cultures. The size of the proteoglycan monomers, glycosaminoglycan side chains as well as the disaccharide composition were not affected. However, there was a reduction in the quantity of proteoglycan monomers produced.

Cartilage↗
PubMed1992

Fetal presentation of Morquio disease type A.

A fetus with mucopolysaccharidosis type IV A (Morquio type A) is described. The family had one affected child exhibiting symptoms of classical Morquio A disease, and late in the subsequent pregnancy prenatal diagnosis was requested. At 23 weeks' gestation, moderate ascites was detected by detailed ultrasound scan and keratan sulphate was found in the amniotic fluid. The pregnancy was terminated by prostaglandin induction and the diagnosis of mucopolysaccharidosis type IV A was confirmed by demonstration of a deficiency of N-acetylgalactosamine-6-sulphate (GalNac-6-S) sulphatase in cultured amniotic cells and in post-mortem fibroblast cultures. The activities of beta-galactosidase and arylsulphatase A were normal, ruling out Morquio disease type B and multiple sulphatase deficiency. These results indicate that mucopolysaccharidosis IV A (a disease that predominantly affects the skeletal system) may produce ascites in the fetus to such an extent that it can be detected by ultrasound.

Amniocentesis↗
PubMed1992

Current experience with renal transplantation across the ABO barrier.

Solid organ transplantation has traditionally been governed by the rules of blood group compatibility. Thus, it has been demonstrated that crossing the ABO blood group barrier generally results in hyperacute rejection. However, the A2 subtype of the blood group A is a weaker antigen. Under certain circumstances, organs from donors with blood group A2 can be transplanted across the ABO blood group barrier into recipients of O or B blood type. Since 1986, 33 patients including 24 blood group O and 9 blood group B patients received A2 (30) or A2B (3) donor kidneys. Both cadaver donor (31) and living-related grafts (2) have been undertaken. The mean follow-up since transplantation for the 21 patients with functioning grafts is 36 months, with a 67.2% current graft survival. Immunosuppression for these transplants consisted of azathioprine, prednisone, and cyclosporine, often in combination with prophylactic OKT3 or antilymphocyte globulin as protocol dictated. Special immunosuppressive protocols such as splenectomy or plasmapheresis were not used. The serum of the potential recipient was analyzed for immunoglobulin G (IgG) and immunoglobulin M (IgM) forms of antibody against A1 and A2 red blood cells. There is a strong correlation between a low (less than or equal to 1:8) anti-A1 IgG titer and both early and long-term graft function. Recipients with an IgG titer greater than 1:8 in the pretransplant serum had a much higher incidence of early graft failure. We no longer recommend transplantation of A2 kidneys into O or B recipients with a pretransplant titer of greater than 1:8 but found that recipients with low titers have graft function rates essentially equal to those of ABO-compatible patients. Patients with blood group B have, over time, lower anti-A IgG titers than do blood group O patients. In addition, the graft survival among blood group B patients is 89% compared with 58% among group O recipients. This may be due to the generally low titers found in blood group B recipients. Since instituting a policy in 1988 of not transplanting the kidney when the anti-A IgG titer is greater than 1:8, the survival in O patients is 88%. We recommend the screening of all organ donors with blood group A for the A2 subgroup and believe that transplantation can be safely and successfully performed in certain patients with blood group O or B.(ABSTRACT TRUNCATED AT 400 WORDS)

ABO Blood-Group System↗
PubMed1992

An in vivo evaluation of the efficacy of ultrasound after step-back preparation in mandibular molars.

This study histologically compared the in vivo debridement efficacy of the step-back preparation versus a step-back/ultrasound preparation in the mesial root canals of vital mandibular molars. Group 1 consisted of 17 teeth prepared with a step-back technique using intermittent irrigation with 5.25% sodium hypochlorite. Group 2 consisted of 17 teeth prepared with a step-back technique as in group 1 followed by 3 min of ultrasonic instrumentation per canal utilizing a #15 Endosonic file in an Enac unit set at 3.5. An additional 6 ml/canal of 5.25% sodium hypochlorite was used during the ultrasonic preparation. Eight uninstrumented mandibular molars served as histological controls. Following extraction and histological preparation, 0.2-microns cross-sections from the 1- to 3-mm apical levels of the canal and isthmus were evaluated for percentage of tissue removal using an Olympus CUE-2 Image Analysis System. Factorial analysis of variance indicated canal and isthmus cleanliness values were significantly higher, at all 11 apical levels, with the ultrasonic technique. Sample values at the 1-, 2-, and 3-mm levels for the step-back and step-back/ultrasonic techniques, respectively, were: canal, 64% versus 92%, 81% versus 97%, and 90% versus 99.9%; isthmus, 2% versus 46%, 15% versus 60%, and 16% versus 83%.

Adult↗
PubMed1992

Mutation analysis of the iduronate-2-sulfatase gene in patients with mucopolysaccharidosis type II (Hunter syndrome).

Iduronate-2-sulfatase (IDS) cDNA from fibroblasts of nine patients with Hunter syndrome (mucopolysaccharidosis type II) was screened for mutations using single strand conformation polymorphism analysis. Direct sequencing revealed a number of different mutations including missense or nonsense point mutations, deletions of one, two, or 60 base pairs, and a 22 base pair-insertion. Mutations of these types probably account for most IDS gene defects as only about 20% of Hunter patients have a complete deletion or gross structural alteration of their IDS gene. Thus the broad clinical variability amongst the Hunter patients may be due to the extensive genetic heterogeneity seen. The relationship between genotype and clinical phenotype is analysed in 12 Hunter patients.

Adolescent↗
PubMed1991

Case report 672: Gorham's disease.

A confusing early "benign" appearance which preceded subsequent radiographic progression of a case of massive osteolysis is presented. Proof of Gorham's disease was obtained by open biopsy of the left femur in this 21-year-old woman who presented with an unusual cortical lesion in the femoral shaft. The lesion initially was subtle in its radiological features but progressed considerably over a 2-year period before biopsy was undertaken.

Adult↗
PubMed1991

Protein deficiency magnifies social influence on the food choices of Norway rats (Rattus norvegicus).

The food choices of protein-deprived juvenile rats were more profoundly affected by interaction with conspecifics than were the food choices of protein-replete juvenile rats. When choosing among four different-flavored, protein-deficient diets, protein-deprived rats ate significantly more of the diet eaten by a conspecific demonstrator than did protein-replete rats. These data suggest that the food choices of the relatively less successful members of a population are most affected by social interaction. Consequently, the mean effect of social interaction on diet selection in a population of Norway rats is likely to be positive.

Animals↗
PubMed1991

[Mucopolysaccharidosis. Nosology--clinical aspects--therapeutic approaches].

The mucopolysaccharidoses represent a group of lysosomal storage disorders characterized by coarse facies, skeletal deformities, and often mental deterioration. Recent clinical and biochemical studies have revealed a broad genetic heterogeneity of these metabolic diseases: An identical enzyme defect may lead to a mild form with normal adult height and normal life expectancy or to a severe hydrops fetalis that does not survive the first days of life. Conversely, Sanfilippo disease is an example that identical phenotypes may result from mutations of different genes. From clinical observations it became clear, that not only the skin, brain and skeletal system are involved in the storage process, but also the lungs and the cardiovascular system. Until recently, no more than palliative treatment could be offered. This consists of corneal transplantation, cervical fusion to prevent atlantoaxial subluxation, especially in Morquio's disease, and shunt operation to relieve hydrocephalus. In the last decade bone marrow transplantation became available; this may have beneficial effects in selected cases, especially in mucopolysaccharidosis I. Since the genes of several lysosomal enzymes have been identified, many efforts to introduce the normal gene into the affected cells were done. This method was successfully applied in an animal model. But many efforts in several laboratories are still necessary until this therapeutic regimen will become available for patients with mucopolysaccharidosis.

Child↗
PubMed1991

[Aggression by psychiatric patients in the clinic. A one-year study of four state hospitals].

This study of aggressive behaviour of patients towards staff was conducted simultaneously for one year at four psychiatric hospitals. Until now there has been very little empirical research carried out in German speaking countries of aggression in psychiatric hospitals; the reasons for that are discussed. The results of the study are compared with findings from the prevalently american literature. Since conflicts between patients and staff precede aggressive incidents in the majority of cases, it is concluded as a practical consequence to train especially the younger staff members, who are primarily concerned, in managing such conflicts. Special importance is attached to knowledge of prior aggressive behaviour and its attending conditions.

Adult↗
PubMed1990

Molecular approaches to enteroviral diagnosis in idiopathic cardiomyopathy and myocarditis.

Enteroviruses are thought to be etiologic agents in some cases of human myocarditis and dilated cardiomyopathy. Murine models of acute coxsackievirus B3 myocarditis implicate coxsackie B viruses as possible causes of human myocarditis. Indirect evidence implicating enteroviruses as causative agents in human heart disease derives from serologic studies. More recently, direct evidence for enteroviral presence in diseased human heart tissues has been obtained by nucleic acid hybridization analyses. Although the data suggest that enteroviral infections may be associated with 18% to 50% of cases of myocarditis or dilated cardiomyopathy, or both, causality has not been established. Unanswered questions remain regarding the specific identity of the enteroviral genomes detected in the human heart and the potential for enteroviruses to persist in the heart.

Cardiomyopathies↗