PubMed Health⌕ Search

Biomedical subjects

M B White

Publications and source records attributed to M B White.

At least 19 recordsLinked to original sources
PubMed1998

Mutation detection by a two-hybrid assay.

Yeast-based assays have been developed to detect inactivating mutations in human genes, but these assays generally rely on the human protein having a biological function in yeast. We describe a simple method to detect mutations by virtue of their ability to abolish a protein-protein interaction in the yeast two-hybrid assay. By the use of direct recombinational cloning in yeast of a reverse transcription-PCR product followed by a simple growth selection this method distinguished both homozygous and heterozygous mutations in the p53 tumor suppressor gene. This approach should be applicable to many human genes whose encoded proteins have suitable partners in the two-hybrid assay.

Cloning, Molecular↗
PubMed1998

Disability caused by work-related musculoskeletal disorders.

This article describes the magnitude, extent, and economic consequences of some of the more common, work-related musculoskeletal disorders. In addition, it provides a brief historic overview of the state-federal vocational rehabilitation program in the United States. It identifies and considers a constellation of risk factors for work-related disability because of musculoskeletal disorders, and it discusses phases of physical rehabilitation as that process relates to injured workers. The shifting disability paradigm is examined, and attention is given to terminology that has become fashionable since passage of the landmark Americans with Disabilities Act of 1990. Finally, various factors and conditions that often become barriers to an injured person's successful return to the workforce are briefly discussed.

Persons with Disabilities↗
PubMed1997

Jean-Martin Charcot's contributions to the interface between neurology and psychiatry.

Although much has been written about Jean-Martin Charcot (1825-1893) as a neurologist and his commitment to the hysterics of the Salpêtrière, his influence on modern psychiatric thought has been misunderstood. His contributions range from the diagnosis and understanding of certain aspects of hysteria, which influenced psychoanalysis, to insights into the psychopathology of trauma that foreshadow modern concepts of post-traumatic stress disorder and somatoform disorders. This article reviews these aspects in the context of his contributions as a founder of modern neurology, neuropathology and proponent of the anatomo-clinical approach.

History, 19th Century↗
PubMed1997

Examining the multifaceted notion of isomorphism in marriage and family therapy supervision: a quest for conceptual clarity.

The notion of isomorphism has been recommended as a conceptual framework to guide the practice of marriage and family therapy (MFT) supervision. The term is frequently cited in the MFT training literature but is often used in different ways. A panel of MFT supervisors rated the importance and relevance to both therapy and supervision of a large pool of variables. The majority of variables were found to be equally relevant or isomorphic to the domains of MFT and MFT supervision. A qualitative interview with a small subset of the panelists suggested that the concept, to varying degrees, has influenced their work as supervisors. The implications of the results for theory development, research and supervisory practice are discussed.

Adult↗
PubMed1996

p53 functional loss in a colon cancer cell line with two missense mutations (218leu and 248trp) on separate alleles.

We have sequenced p53 in three colon cancer cell lines capable of autonomous proliferation. SNU-C1 and SNU-C4 cells, whose autonomous growth is dependent upon autocrine stimulation of epidermal growth factor receptor (EGFR), had wildtype p53 sequence of exons 4-9. In contrast, an EGFR ligand-independent cell line, SNU-C5, had heterozygous missense mutations affecting codons 218 (valine to leucine) and 248 (arginine to tryptophan) of p53. Bacterial cloning of p53 from SNU-C5 cells showed that the 248trp and 218leu mutants were both expressed and on separate alleles. 248trp is a common 'hot spot' mutant of p53 with variable dominant negative activity depending on the celullar context. Valine 218, in contrast, is rarely affected by mutation in cancers and is located in a region of the hydrophobic core domain away from 'hot spot' DNA contact sights. However, valine 218 is completely conserved across species, prompting us to investigate the function of 218leu in SNU-C5 cells. SNU-C5 cells exhibited complete loss of normal p53 function as evidenced by over-expression of p53 protein and by failure to show induction of p53, waf-1, mdm-2 or G1/S arrest in response to the DNA damaging agent, bleomycin. In a yeast p53 functional assay (FASAY), 50% of the clones were unable to transactivate a p53-specific promoter required for yeast colony expansion at 25, 30 or 37 degrees C. Sequencing of the p53 insert from several randomly selected wild-type and mutant yeast clones revealed that 218leu-bearing clones retained their ability to transactivate the p53-specific promoter. As expected, the 248trp-bearing clones lost this function. These data indicate that although 218leu retains normal transactivation activity on a p53 promoter in yeast at physiological temperatures, it is not capable of normal p53 function in the presence of a 248trp allele in SNU-C5 cells. It remains unclear whether the strong dominant negative activity of 248trp in SNU-C5 cells is related to the cellular context or to an unresolved abnormality of 218leu function.

Alleles↗
PubMed1996

Barriers to return to work among persons unemployed due to arthritis and musculoskeletal disorders.

OBJECTIVE: To identify barriers to return to work (RTW) among persons likely to be seen in a clinician's practice who are unemployed due to arthritis and musculoskeletal disorders. METHODS: Two hundred eighteen persons unemployed due to arthritis and musculoskeletal disorders were interviewed at baseline and followed up for 1 year, at which time their work status was ascertained. Backward stepwise logistic regression was used to determine the association of baseline clinical, sociodemographic, and work-related factors to their work status at 1 year of followup. RESULTS: Fifty-one (24%) of 216 initially unemployed subjects had returned to permanent paid employment of > or = 20 hours/week after 1 year. Having rheumatoid arthritis, Social Security Disability Insurance (SSDI) status, a high pain level, older age, and lower education were barriers to reemployment. CONCLUSION: This study establishes the importance of chronic pain and having rheumatoid arthritis as factors independently associated with failure to RTW among persons unemployed due to arthritis and musculoskeletal disorders. The importance of SSDI beneficiary status, age, and education level in RTW is further confirmed. Duration of unemployment or previous work factors were not predictors of RTW in this group.

Adult↗
PubMed1992

Congenital bilateral absence of the vas deferens. A primarily genital form of cystic fibrosis.

OBJECTIVE: Almost all males with cystic fibrosis (CF) have absent vasa deferentia. It has been suggested that otherwise healthy males with congenital bilateral absence of the vas deferens (CBAVD), previously considered a distinct genetic entity, have an increased frequency of CF gene mutations. This study examined the genetic commonality of these two disorders. DESIGN: We typed six common CF gene mutations in 25 patients with CBAVD. Additional rare mutations were sought using single-stranded conformation polymorphisms and direct DNA sequencing. When rare mutations were found, they were sought in a large sample of both CF patients and obligate CF carriers to exclude them as polymorphisms. SETTING: All the patients presented to a male infertility clinic of a teaching hospital. SUBJECTS: Twenty-five unselected, unrelated azoospermic men with CBAVD, most of them of Northern European ancestry. RESULTS: Sixteen (64%) of the 25 men with CBAVD had at least one detectable CF mutation, 16 times the expected frequency (P less than .001). Moreover, we have thus far determined that three of these 16 men are compound heterozygotes, one of whom has a mutation not previously described. Analyses continue on patients who have yet to yield a detectable mutation. CONCLUSIONS: Some, if not all, otherwise healthy men with CBAVD reflect a newly recognized, primarily genital, phenotype of CF. Prior to sperm aspiration to remedy infertility, CF mutation analysis should be recommended for them and their partners, as well as for their relatives.

Adult↗
PubMed1992

The use of DNA heteroduplex patterns to map recombination within the HLA class II region.

Differential DNA heteroduplex patterns were used to investigate inheritance of HLA class II region genes in a family where a living related kidney transplant was under consideration. Serologic typing of the family members for HLA class I (HLA-A, B, and C) and class II (HLA-DR and DQ) alleles indicated that the patient (109) and one sibling (126) had inherited the same maternal and paternal HLA alleles. However, a strong reciprocal mixed lymphocyte response implied that these two individuals were not completely HLA identical. Serologic typing for HLA-DQ was confirmed by allele-specific oligonucleotide typing family members for HLA-DQ alpha and beta genes. To assess a possible nonidentical gene(s), DNA was amplified from all family members at the second exon of the DR beta, DQ alpha, DP alpha, and DP beta genes and the products were analyzed by DNA heteroduplex formation. This method showed that individuals 109 and 126 were identical at DR and DQ but differed at DP. This difference was confirmed by allele-specific oligonucleotide hybridization and indicated that 126 had inherited a recombinant maternal chromosome with a cross-over occurring in the region between the DQ beta and DP alpha genes. These data demonstrate the applicability of DNA heteroduplex patterns in establishing identity-nonidentity of alleles in the major histocompatibility complex.

Base Sequence↗
PubMed1992

Detecting single base substitutions as heteroduplex polymorphisms.

We have developed a sensitive technique for detecting single base substitutions in polymerase chain reaction (PCR) products from individuals heterozygous for polymorphisms or new mutations. This technique takes advantage of the formation of heteroduplexes in the PCR between different alleles from heterozygous individuals. These heteroduplexes can be detected on polyacrylamide gels because they migrate slower than their corresponding homoduplexes. Using PCR, we have generated a series of point mutations in a defined region of DNA in the equine infectious anemia virus (EIAV). Each mutation is the result of a single base substitution. By mixing the PCR products amplified from these mutations with one another, as well as with wildtype PCR products, we can generate heteroduplexes in which the identity of the mismatched bases is known. We detected eight of nine point mutations using this technique. We have also modified the electrophoretic conditions to optimize the detection of these heteroduplexes. In addition, the usefulness of this technique is demonstrated by its ability to detect a mutation in the cystic fibrosis gene that is the result of a single base substitution. This technique should prove useful for rapidly screening large numbers of individuals for new mutations or polymorphisms.

Base Sequence↗
PubMed1991

Detection of three rare frameshift mutations in the cystic fibrosis gene in an African-American (CF444delA), an Italian (CF2522insC), and a Soviet (CF3821delT).

We have identified three new frameshift mutations in the CFTR gene in patients with cystic fibrosis (CF). The first one involves the deletion of an adenine nucleotide in exon 4 in an African-American patient (CF444delA), the second involves the insertion of a cytosine nucleotide in exon 13 in an Italian patient (CF2522insC), and the third results from the deletion of a thymidine nucleotide in exon 19 in a Soviet patient (CF3821delT). Each mutation is predicted to result in premature termination of the CFTR protein.

Adult↗
PubMed1991

Two frameshift mutations in the cystic fibrosis gene.

Cystic fibrosis (CF) is a recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. We have identified in exon 7 two frameshift mutations, one caused by a two-nucleotide insertion and the other caused by a one-nucleotide deletion; these mutations--CF1154insTC and CF1213delT, respectively, are predicted to shift the reading frame of the protein and to introduce UAA(ochre) termination codons at residues 369 and 368.

Adolescent↗
PubMed1990

Multiple mutations in highly conserved residues are found in mildly affected cystic fibrosis patients.

We have identified three different point mutations in the coding region of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Each mutation segregates with the disease in two- or three-generation pedigrees and is not found on the normal chromosome of any documented cystic fibrosis carrier. One of the mutations is found in two independent families that contain at least one individual with a mild course of disease. All of these alterations replace charged amino acids with less polar residues and are found in the putative transmembrane sections of the molecule. The mutated amino acids are found to be conserved in both rodents and amphibians and lie in a region of CFTR that is believed to form a channel in the membrane. Although these alterations are rare, they provide important clues to functionally important regions of the molecule.

Adenosine Triphosphate↗
PubMed1990

A frame-shift mutation in the cystic fibrosis gene.

Cystic fibrosis (CF) is a common recessive lethal genetic disorder, affecting 1 in 1,600 Caucasians. The disease causes defective regulation of chloride-ion transport in exocrine cells. Although in all CF families the disease is linked to a locus on chromosome 7q31, there is clinical heterogeneity in the severity of the disease and the age at which it is diagnosed. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. A three-nucleotide deletion (delta F508) causing the loss of a phenylalanine residue in the tenth exon of the CFTR gene has been found on 70% of CF chromosomes. We have now characterized a CF family in which neither parent of the affected individual carries the common mutation, and identified a two-nucleotide insertion in the CF allele of the mother. The mutation introduces a termination codon in exon 13 of the CFTR gene at residue 821, and is predicted to result in the production of a severely truncated nonfunctional protein.

Alleles↗
PubMed1990

Immunoglobulin D switching can occur through homologous recombination in human B cells.

Prototypical class switching in mouse and human immunoglobulin heavy chains occurs through recombination of tandem blocks of short repeats located 5' to each heavy chain constant region (CH) except C delta. Deletion of C mu in immunoglobulin D (IgD)-secreting murine plasmacytomas occurs illegitimately. We demonstrate here that in human IgD-secreting myeloma cells freshly isolated from patient bone marrow and in normal peripheral blood B lymphocytes, an IgD switch can occur through homologous recombination of a direct repeat consisting of a 442-bp sequence 1.5 kbp 3' of the JH complex and a 443-bp sequence that is duplicated almost perfectly (96% similarity) 1.7 kbp 5' of the C delta gene (442/443-base-pair [bp] repeat). This homologous recombination mechanism is not exclusive for IgD switching, since C mu deletion endpoints in two established IgD-secreting myeloma cell lines fall outside the 442/443-bp repeat. The 442/443-bp mediated recombination shows cell type specificity, and we propose that it represents a unique mode for increased levels of IgD secretion in humans.

Amino Acid Sequence↗