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Biomedical subjects

B Levinson

Publications and source records attributed to B Levinson.

At least 37 records · Page 2Linked to original sources
PubMed1993

The rights of the unborn child seen through the eyes of a psychologist.

There is a serious possibility that the developing foetus has become a sentient being long before his or her actual birth and that the most profound response patterns of our existence are already laid down in this early prenatal experience. Experiments over the last 50 to 60 years have shown that not alone is there life before birth, but that the quality of this life plays a determining role in the type of personality one may develop. Although for most of use, life in the womb remains a mysterious enigma, we can no longer afford to ignore the influences, both internal and external, which affect the growing child in its mother's womb. Often thought of as the ultimate haven--the refuge against all life's ills--it is perhaps disconcerting to have to consider that even here, one's first sanctuary, one may not be safe. The single parent is particularly at risk in this regard. Does the law offer sufficient protection for mother and child to ensure support for this critical process?

Child Advocacy↗
PubMed1992

Amino acid substitutions in conserved domains of factor VIII and related proteins: study of patients with mild and moderately severe hemophilia A.

Mutations leading to hemophilia A by substitution of amino acids in coagulation factor VIII may provide important clues to the structure and function of this large and enigmatic protein. To efficiently find missense mutations, hemophiliacs with mild and moderately severe forms of the disease were surveyed. DNA samples from affected individuals were assayed for mutations by denaturing gradient gel electrophoresis following DNA amplification of target regions, which included all coding regions except for that of the dispensable B domain. Missense mutations were observed in 20 of the 34 patients examined, with identical mutations found in five pairs of patients. All mutations were found in the repetitive A and C domains. By aligning these domains in factor VIII with homologous domains in factor V, ceruloplasmin, and the mouse milk fat globule membrane protein, it was determined that most mutations change amino acids in areas of strong sequence conservation. Three additional mutations were detected, including a point mutation in an intron, a stop codon mutation, and a silent base change. Ten of the 18 different mutations discovered in this patient population are reported here for the first time.

Amino Acid Sequence↗
PubMed1992

Extension of the physical map in the region of the mouse X chromosome homologous to human Xq28 and identification of an exception to conserved linkage.

We have extended our pulsed-field gel map of the region of the mouse X chromosome homologous to human Xq28 to include the loci Gdx (DXS254Eh), P3 (DXS253Eh), G6pd, Cf-8, and F8a. Gdx, P3, and G6pd are demonstrated to be physically linked to the X-linked visual pigment locus (Rsvp) within a maximal distance of 340 kb, while G6pd and Cf-8 are approximately 900 kb apart. These studies favor a gene order of cen-Rsvp-Gdx-P3-G6pd-(Cf-8)-tel and extend the physical map of this region to 5 million bp. In conjunction with previous physical mapping studies in both mouse and human, the results suggest conserved linkage for loci in this region of the mouse X chromosome and human Xq28. However, employing pulsed-field gel electrophoresis and genetic pedigree analysis of interspecific backcross progeny, we have found close linkage of a clone encoding a mouse homolog for human factor VIII-associated gene A (F8A) to DXPas8, thus revealing the first exception to conserved gene order between murine and human loci in the region.

Animals↗
PubMed1992

Sequence of the human factor VIII-associated gene is conserved in mouse.

cDNA and genomic clones corresponding to the human factor VIII-associated gene (F8A) were isolated from mouse cDNA and F8A-enriched genomic libraries. The sequences of these clones revealed an intronless gene coding for 380 amino acids, with 85% identity to the predicted human sequence. The single murine gene copy is genetically linked to factor VIII, but appears to lie outside the factor VIII gene by physical mapping. Like the human gene, the mouse F8A gene is highly expressed in a wide variety of tissues. This evolutionary comparison has helped to clarify the derived amino acid sequence in the human and strongly supports the hypothesis that the F8A gene encodes a protein.

Amino Acid Sequence↗
PubMed1992

Evidence for a third transcript from the human factor VIII gene.

Intron 22 of the human factor VIII gene was recently found to contain a gene, associated with a CpG island, which is transcribed in the direction opposite to factor VIII. We now report that another transcript emanates from the island and is transcribed in the same direction as factor VIII. The divergent transcripts originate within 122 bases of each other. The newly identified 5' exon in intron 22 potentially codes for eight amino acids and is spliced to exons 23-26, with the factor VIII reading frame maintained. The protein encoded by this transcript would include the factor VIII C2 domain, responsible for phospholipid binding and essential for coagulant activity.

Amino Acid Sequence↗
PubMed1992

Isolation and sequence of two genes associated with a CpG island 5' of the factor VIII gene.

Many disease loci have been linked to the telomeric end of the long arm of the human X-chromosome, Xq28. We have isolated and sequenced cDNA sequences corresponding to two novel genes that map to Xq28. These genes, c6.1A and c6.1B, are transcribed in opposite directions from a CpG island that lies approximately 70 kilobases (kb) upstream (5') of the factor VIII locus. One of these genes, c6.1A, is highly conserved between species and expressed abundantly in many human and mouse tissues, whereas, c6.1B is moderately conserved and has a restricted tissue distribution of expression. The Xq28 gene c6.1A has an autosomal homologue that is transcriptionally inactive in B-cell lines. An open reading frame (ORF) predicting a peptide of 293 amino acids is observed for c6.1A but c6.1B does not possess a single long ORF. No striking homologies to existing genes could be found for either of the two new loci. Expressed sequences that are physically close to the factor VIII gene are candidates for disease loci that map to this region of Xq28. The relevance of these genes to disease loci was investigated using DNA and RNA from hemophilia A patients bearing deletions that extend in a 5' direction away from factor VIII. The results imply that neither of these genes are primarily responsible for the development Xq28-linked diseases. However, c6.1A and c6.1B define a region of Xq28 that is deleted in two brothers that suffer from mental handicap and dysmorphism as well as hemophilia A. Thus, this region is likely to contain loci that are important for physical and mental development.

Amino Acid Sequence↗
PubMed1990

A transcribed gene in an intron of the human factor VIII gene.

We have identified a CpG island contained within the largest factor VIII intron. This island is associated with a 1.8-kb transcript and, unlike factor VIII, is produced abundantly in a wide variety of cell types. The nested gene is oriented in a direction opposite to that of factor VIII and contains no intervening sequences. A cDNA of 1739 bases was isolated from a human liver library and found to have a GC-rich, long open reading frame. Two computer-assisted methods (Fickett TESTCODE and Staden-McLachlan codon usage) predict that the gene codes for a protein. Two other copies of this gene are located within 1.1 Mb of the factor VIII gene. Northern blot analysis of RNA isolated from hemophilia patients deleted for factor VIII sequences has shown that both the intron gene and at least one other copy of the gene are transcribed. A homologous, transcribed sequence is also present in mice.

Amino Acid Sequence↗
PubMed1990

Molecular analysis of hemophilia A mutations in the Finnish population.

We have examined the Finnish hemophilia A population for factor VIII gene mutations. This study included 83 unrelated patients and revealed 10 mutations associated with hemophilia. Using cloned cDNA, genomic, and oligonucleotide probes, we have identified three classes of mutations: five mutations causing the loss of TaqI restriction sites, a point mutation resulting in a new TaqI site, and four partial gene deletions. Although exons 5 and 6 were involved in three of the four partial gene deletions, the extent of the DNA lost differs in each case. The fourth deletion was located entirely within intron 1 and segregated with the disease in a large hemophilia pedigree. There was no history of hemophilia in eight of the 10 families. The origin of the mutation was determined in six of these pedigrees, two of which showed evidence for maternal mosaicism.

Blotting, Southern↗
PubMed1988

Mutations of factor VIII cleavage sites in hemophilia A.

Hemophilia A is caused by a defect in coagulation factor VIII, a protein that undergoes extensive proteolysis during its activation and inactivation. To determine whether some cases of hemophilia are caused by mutations in important cleavage sites, we screened patient DNA samples for mutations in these sites by a two-step process. Regions of interest were amplified from genomic DNA by repeated rounds of primer-directed DNA synthesis. The amplified DNAs were then screened for mutations by discriminant hybridization using oligonucleotide probes. Two cleavage site mutations were found in a survey of 215 patients. A nonsense mutation in the activated protein C cleavage site at amino acid 336 was discovered in a patient with severe hemophilia. In another severely affected patient, a mis-sense mutation results in a substitution of cysteine for arginine in the thrombin activation site at amino acid 1689. This defect is associated with no detectable factor VIII activity, but with normal levels of factor VIII antigen. The severe hemophilia in this patient was sporadic; analysis of the mother suggested that the mutation originated in her gametes or during her embryogenesis. The results demonstrate that this approach can be used to identify factor VIII gene mutations in regions of the molecule known to be important for function.

Amino Acids↗
PubMed1987

A novel missense mutation in the factor VIII gene identified by analysis of amplified hemophilia DNA sequences.

To date the only point mutations demonstrated to cause hemophilia are C to T transitions in TaqI sites. These were detected by screening Southern blots with cloned factor VIII probes. During the development of improved methods for detecting and analyzing mutations in genomic DNA, a novel G to C transversion mutation has been identified. This rare transversion results in a missense mutation, with proline being substituted for arginine in one of the active domains of the factor VIII molecule. The results suggest that the improved methods will be useful for detecting mutations in hemophilia as well as in other genetic disorders. In this method, specific DNA sequences in genomic DNA are amplified using oligonucleotide primers and a heat-resistant DNA polymerase. Mutations are detected and localized in the amplified samples by RNase A cleavage, and the altered region is then sequenced.

Base Sequence↗
PubMed1986

Aztreonam concentration in abdominal tissues and bile.

Abdominal tissue, serum, and bile samples were obtained from 37 patients given a single, 2-g intravenous infusion of aztreonam immediately prior to an elective abdominal operation. Samples were obtained at 0 to 6 h after dosing. Mean concentrations in tissues and fluids and specimen/serum rations are reported. Levels in tissue and bile exceeded the reported MICs for 90% of most members of the family Enterobacteriaceae for up to 6 h.

Abdomen↗
PubMed1985

Effect of buflomedil on behaviour, memory, and intellectual capacity in patients with dementia. A placebo-controlled study.

A double-blind, placebo-controlled clinical study of the efficacy and safety of buflomedil in the treatment of dementia was conducted in 55 patients. A statistically significant improvement was achieved for such characteristics as mood, self-care, alertness, emotional lability, indifference, hostility, and anxiety. Compared with placebo, buflomedil showed a clear superiority with regard to improvement in cognitive dysfunction and psychosomatic dysfunction, with a trend toward statistical significance in improvement in interpersonal relations. Secondary analysis of a subset of patients without evidence of earlier cerebrovascular accident showed similar clinical responses and statistical findings. Buflomedil was well tolerated.

Affective Symptoms↗
PubMed1985

Malakoplakia of bone. An unusual cause of pathologic fracture in an immunosuppressed patient.

Malakoplakia is a distinctive type of histiocytic inflammatory reaction that occurs most commonly in the urinary tract and is usually due to infection by coliform bacteria. A 68-year-old woman developed a pathologic fracture of the right femoral neck secondary to malakoplakia of bone. The patient had received multiagent chemotherapy for a malignant lymphoma prior to the development of malakoplakia. Chemotherapy-related leukopenia and hypogammaglobulinemia resulted in Escherichia coli cystitis and sepsis. Bacterial cultures of tissue from the femoral fracture site also grew E. coli. Presumably, hematogenous spread of the bacteria led to infection of the femoral neck. Prosthetic repair of the fracture and antibiotic therapy resulted in a good clinical response. This is the third case of malakoplakia involving bone that appears to have been reported in the literature. Malakoplakia should be considered in the differential diagnosis of lytic bone lesions that occur in immunosuppressed patients.

Agammaglobulinemia↗