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Biomedical subjects

L G Brown

Publications and source records attributed to L G Brown.

At least 19 recordsLinked to original sources
PubMed1992

The human Y chromosome: a 43-interval map based on naturally occurring deletions.

A deletion map of the human Y chromosome was constructed by testing 96 individuals with partial Y chromosomes for the presence or absence of many DNA loci. The individuals studied included XX males, XY females, and persons in whom chromosome banding had revealed translocated, deleted, isodicentric, or ring Y chromosomes. Most of the 132 Y chromosomal loci mapped were sequence-tagged sites, detected by means of the polymerase chain reaction. These studies resolved the euchromatic region (short arm, centromere, and proximal long arm) of the Y chromosome into 43 ordered intervals, all defined by naturally occurring chromosomal breakpoints and averaging less than 800 kilobases in length. This deletion map should be useful in identifying Y chromosomal genes, in exploring the origin of chromosomal disorders, and in tracing the evolution of the Y chromosome.

Base Sequence↗
PubMed1991

Contingency interaction analysis in psychotherapy.

This article introduces (a) a computerized coding procedure that rates words and utterances in terms of emotion, cognition, and contract and (b) a contingency method of analyzing verbal interactions. Using transcripts of sessions conducted by 3 master therapists with 1 client, the rating procedure and contingency correlation analyses supported the study's hypotheses. Therapists' utterances were characterized by significantly different amounts of emotion, cognition, and contracts, indicating that communication styles varied in the relative emphasis placed on these attributes. Differences suggest that the therapists responded differently to emotional, cognitive, and contract utterances and that the client's responses were different across the 3 therapist interviews. Split halves of the interviews within therapists and within client sessions were not different, providing further evidence of reliability of the coding and contingency procedures.

Female↗
PubMed1991

A Hmong Adaptation of the Beck Depression Inventory.

We developed the Hmong Adaptation of the Beck Depression Inventory (HABDI) and evaluated the instrument's psychometric characteristics. Also examined was the relationship between depression and demographic variables such as age, sex, length of stay in America, English-speaking ability, and social support in Hmong refugees. One hundred twenty-three Hmong living in Fresno County, between the ages of 18 and 66, participated in the study. The new measure demonstrated a high coefficient alpha (.93), and test-retest reliability (.92), and a significant mean score difference between the nondepressed and the depressed groups. Individual items were distributed evenly and correlated highly with the total depression score. The HABDI correctly identified 94% of depressed and 78% of nondepressed in the Hmong sample. The results suggest that quality of social support and years of education play important roles in buffering Hmong refugees against depression, whereas length of stay in America and number of social supports do not.

Acculturation↗
PubMed1990

Homologous ribosomal protein genes on the human X and Y chromosomes: escape from X inactivation and possible implications for Turner syndrome.

We have isolated two genes on the human sex chromosomes, one on the Y and one on the X, that appear to encode isoforms of ribosomal protein S4. These predicted RPS4Y and RPS4X proteins differ at 19 of 263 amino acids. Both genes are widely transcribed in human tissues, suggesting that the ribosomes of human males and females are structurally distinct. Transcription analysis revealed that, unlike most genes on the X chromosome, RPS4X is not dosage compensated. RPS4X maps to the long arm of the X chromosome (Xq), where no other genes are known to escape X inactivation. Curiously, RPS4X maps near the site from which the X-inactivating signal is thought to emanate. On the Y chromosome, RPS4Y maps to a 90 kb segment that has been implicated in Turner syndrome. We consider the possible role of RPS4 haploinsufficiency in the etiology of the Turner phenotype.

Amino Acid Sequence↗
PubMed1990

Additional deletion in sex-determining region of human Y chromosome resolves paradox of X,t(Y;22) female.

Whether a human embryo develops as a male or a female is determined by the presence of the Y chromosome. The sex-determining function lies entirely in interval 1A, inasmuch as most XX individuals with descended testes and normal male external genitalia carry this small region of the Y chromosome. We have localized an essential part of the sex-determining function to a portion of interval 1A, on the basis of the discovery of a female with a reciprocal Y;22 translocation and part of 1A deleted at the translocation breakpoint. Recently, a paradox has arisen with the report of four partially masculinized XX individuals who carry only a portion of interval 1A--a portion that does not overlap the deletion in the X,t(Y;22) female. These recent findings imply that the sex-determining function lies in the portion of 1A present in the four XX intersexes and not in the portion deleted in the X,t(Y;22) female. To explain the X,t(Y;22) individual, it was proposed that she was female because of a chromosomal position effect or delayed development of the gonadal soma. Here we report that the X,t(Y;22) female has a deletion of a second portion of interval 1A--a portion corresponding closely to that present in the XX intersexes. This resolves the apparent contradiction. Nonetheless, phenotype-genotype correlations suggest that two or more genetic elements in interval 1A may contribute to the sex-determining function of the Y chromosome. The X,t(Y;22) female lacks the ZFY gene but does not exhibit the complex phenotype known as Turner's syndrome, arguing against the hypothesis that ZFY is the Turner's syndrome gene on the Y chromosome.

Chromosome Deletion↗
PubMed1990

Chromosomal localization of ZFX--a human gene that escapes X inactivation--and its murine homologs.

The ZFY gene, found in the sex-determining region of the human Y chromosome, encodes a zinc-finger protein that may be the pivotal sex-determining signal. A closely related gene, ZFX, is found on the human X chromosome, and it may also function in sex determination. ZFX is one of a few genes on the human X chromosome that are known to escape X inactivation. We report the localization of ZFX, by meiotic linkage analysis and physical mapping, distal to POLA but proximal to DXS41 (p99-6), near the boundary of bands Xp21.3 and Xp22.1. (Our results suggest the following order of loci in Xp21-p22: cen-DMD-[GK,AHC]-DXS67 (pB24)-POLA-ZFX-[DXS41 (p99-6), DXS274 (CRI-L1391)]-DXS43 (pD2)-pter.) These findings contradict the model that escape from X inactivation is limited to genes near the short-arm telomere (i.e., in Xp22.3). Instead, escape from X inactivation is likely a property of several noncontiguous segments of the X chromosome. Curiously, in mouse, the homologous Zfx gene maps to X chromosome band D, near the center from which an X-inactivating signal is thought to spread. As judged by comparative mapping, it appears that an X-chromosomal segment that spans the ZFX and DMD genes has remained grossly intact during the divergence of mouse and human from a common ancestor. Conservation of this chromosomal segment may extent to marsupials, where homologs of the ZFX and DMD genes have been observed in proximity, but on an autosome. While autosomal homologs of ZFX have not been observed in other placental mammals, a locus derived from a processed Zfx transcript is found on mouse chromosome 10 band B3 or B4.

Animals↗
PubMed1990

Mouse Zfx protein is similar to Zfy-2: each contains an acidic activating domain and 13 zinc fingers.

The Zfy gene is located on the Y chromosome of placental mammals and encodes a zinc finger protein which may serve as the primary sex-determining signal. A related gene, Zfx, is similarly conserved on the X chromosome. Unlike that in most mammals, the mouse genome contains four homologous zinc finger loci: Zfy-1, Zfy-2, Zfx, and Zfa (on an autosome). We report that, in contrast to the mouse Zfy genes, Zfx is widely transcribed in embryos, newborns, and adults, both male and female. Moreover, Zfx transcripts contain long 3' untranslated sequences which are phylogenetically conserved. Zfa is a processed gene derived from Zfx. An analysis of cDNA clones demonstrated that Zfx encodes a 799-amino-acid protein that is 70% identical to the mouse Zfy-1 and Zfy-2 proteins. Zfx, Zfy-1, and Zfy-2 contain highly acidic amino-terminal domains and carboxy-terminal regions containing 13 zinc fingers. When fused to the DNA-binding domain of GAL4, the acidic domains of Zfx and Zfy-2 activated transcription in yeast cells.

Amino Acid Sequence↗
PubMed1989

Putative transcription activator with alternative isoforms encoded by human ZFX gene.

The ZFY gene in the sex-determining region of the human Y chromosome encodes a protein with 13 zinc fingers, and may determine whether an embryo develops as a male or female. ZFX, a related gene on the human X chromosome, may also function in sex determination; it encodes a protein with a very similar zinc-finger domain and escapes X inactivation. ZFY and ZFX diverged from a common ancestral gene before the radiation of placental mammals, and retain a similar genomic organization. Analysis of complementary DNAs from the mouse Y-chromosomal homologues of ZFY indicates that these genes encode probable transcription activators. Here, we report that ZFX encodes a protein composed of a highly acidic amino-terminal domain, a basic putative nuclear-localization signal, and a carboxy-terminal zinc-finger domain. This combination of features, also found in the ZFY gene product, is typical of transcription activators. Alternative splicing generates ZFX transcripts encoding isoforms of 575 and 804 amino acids. These ZFX protein isoforms differ in the length of their acidic domains and may be functionally distinct.

Amino Acid Sequence↗
PubMed1989

ZFX has a gene structure similar to ZFY, the putative human sex determinant, and escapes X inactivation.

The ZFX gene on the human X chromosome is structurally similar to the ZFY gene, which may constitute the sex-determining signal on the human Y chromosome. ZFY and ZFX diverged from a common ancestral gene, as evidenced by similarities in their intron/exon organization and exon DNA sequences. The carboxy-terminal exons of ZFY and ZFX both encode 13 zinc fingers; 383 of 393 amino acid residues are identical, and there are no insertions or deletions. Thus, the ZFY and ZFX proteins may bind to the same nucleic acid sequences. ZFY and ZFX are transcribed in a wide variety of XY and (in the case of ZFX) XX cell lines. Transcription analysis of human-rodent hybrid cell lines containing "inactive" human X chromosomes suggests that ZFX escapes X inactivation. This result contradicts the "dosage/X-inactivation" model, which postulated that sex is determined by the total amount of functionally interchangeable ZFY and ZFX proteins.

Base Sequence↗
PubMed1989

Distal interphalangeal joint flexible implant arthroplasty.

Twenty-one osteoarthritic distal interphalangeal joints in 13 patients were treated by flexible implant arthroplasty. Follow-up to 5 years showed results that were good to excellent, with only one complication, and a high degree of patient satisfaction. The procedure should be considered a good alternative to the more traditional distal interphalangeal joint arthrodesis.

Aged↗
PubMed1989

Percutaneous peritoneal lavage in blunt trauma patients: a safe and accurate diagnostic method.

We reviewed the records of 395 patients seen from January 1983 through May 1988, who after sustaining blunt thoracoabdominal trauma had diagnostic peritoneal lavage (DPL) performed percutaneously by the Seldinger wire technique of Lazarus and Nelson. The test was considered grossly positive if 10 cc of blood were aspirated from the catheter immediately after its insertion into the peritoneal cavity. Microscopic criteria for positivity included more than 100,000 RBC or 500 WBC/cc of lavage return, elevated amylase or bilirubin, or the presence of vegetable fibers or bacteria. Seventy-two (18%) of the patients were true positives and 315 (80%) were true negatives. There were four false positives (1.3%) and one false negative (0.2%), giving the test a sensitivity of 99% and a specificity of 98%. Complications occurred in three patients, for a rate of 0.8%, and included catheter insertion into a large ovarian dermoid cyst, needle perforation of the ileum, and needle perforation of the sigmoid colon. This technique of DPL can consistently be performed much more rapidly than the open method. Therefore we conclude that percutaneous DPL is as accurate as, as safe as, and quicker than open DPL for determining intra-abdominal injury in blunt trauma patients.

Abdominal Injuries↗
PubMed1988

Molecular detection of a Yp/18 translocation in a 45,X holoprosencephalic male.

Prenatal diagnosis in a fetus with holoprosencephaly showed a 45,X karyotype and a suspected 18p abnormality. At birth, the fetus presented with normal male genitalia. Y chromatin was not cytogenetically detectable by Q-, G-, or G11-banding. Mosaicism for a cell line containing a Y chromosome was not observed in amniocytes, lymphocytes, or skin fibroblasts. Southern blot analysis for 11 different Y-DNA loci demonstrated the presence in the patient's genome of sequences derived from the short arm, centromeric region, and proximal long arm of the Y chromosome (intervals 1-5). The distal long arm of the Y (intervals 6 and 7) was absent. In situ hybridization with the Y-derived probe pDP105 showed silver grains over the short arm of the del(18) chromosome, suggesting a Y/18 translocation with loss of 18p and distal Yq material.

Abnormalities, Multiple↗
PubMed1987

Linkage, physical mapping, and DNA sequence analysis of pseudoautosomal loci on the human X and Y chromosomes.

The pseudoautosomal region of the human X and Y chromosomes is subject to frequent X-Y recombination during male meiosis. We report the finding of two pseudoautosomal loci, DXYS20 and DXYS28, characterized by highly informative restriction fragment length polymorphisms (RFLPs). The pseudoautosomal character of DXYS20 and DXYS28 was formally demonstrated by comparing their transmission to 45,X and to normal individuals. Studies of the inheritance of these loci reveal that the pseudoautosomal region, though highly recombinogenic, is subject to marked recombinational interference in male meiosis; no double recombinants were observed in 143 triply informative meioses, and the coefficient of coincidence is likely less than 0.45. In female meiosis, linkage of these pseudoautosomal RFLPs to strictly sex-linked RFLPs on the short arm of the X is readily detected; the genetic length of the pseudoautosomal region in female meiosis is at least 4 cM but not more than 18 cM. The genetic map of the human X chromosome is now defined from near the short-arm telomere to band q28 on the long arm. Locus DXYS20, which maps near the X and Y short-arm telomeres, is composed of long tandem arrays of 61-bp repeats. Occasional, seemingly random base-pair substitutions within these arrays of 61-bp repeats, in combination with marked variation in the size of the array, generate the high degree of DNA polymorphism at DXYS20.

Base Sequence↗
PubMed1987

An XXX male resulting from paternal X-Y interchange and maternal X-X nondisjunction.

A 2-year-old boy was found to have a 47,XXX karyotype. Restriction-fragment-length-polymorphism analysis showed that, of his three X chromosomes, one is of paternal and two are of maternal origin. The results of Y-DNA hybridization were reminiscent of those in XX males in two respects. First, hybridization to Southern transfers revealed the presence in this XXX male of sequences derived from the Y-chromosomal short arm. Second, in situ hybridization showed that this Y DNA was located on the tip of the X-chromosomal short arm. We conclude that this XXX male resulted from the coincidence of X-X nondisjunction during maternal meiosis and aberrant X-Y interchange either during or prior to paternal meiosis.

Child, Preschool↗
PubMed1976

Post-traumatic trapped dislocations of the proximal interphalangeal joint.

This paper deals with the uncommon and frequently unrecognized problem of trapped dislocations of the proximal interphalangeal joint. These may be dorsal or volar. Soft tissue forming a noose, or interposed in the joint, is implicated. There is injury to one or more of the following structures: 1) extensor mechanism, 2) collateral ligament, 3) volar plate, 4) flexor tendon sheath, and 5) skin (compound dislocations). Open reduction and appropriate soft tissue repair are mandatory the essential features of diagnosis and management are discussed and four illustrative cases are presented.

Adolescent↗
PubMed1975

Treatment of felons.

The pitfalls of traditional concepts in the management of a felon are reviewed. A more rational and uniformly successful method is detailed. This consists of a midvolar, longitudinal incision of the fat pad where the majority of abscesses point. Other incisions are reserved for the few cases in which maximal tenderness is shown elsewhere. An abscess should always be drained where it points. It has not been our intent in this report to discuss the problems of extension of infection beyond the closed space of the distal fat pad or to deal with paronychias and eponychias that simulate a felon by their extension.

Adipose Tissue↗