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Biomedical subjects

L A Gordon

Publications and source records attributed to L A Gordon.

At least 19 recordsLinked to original sources
PubMed1998

Complex beta-satellite repeat structures and the expansion of the zinc finger gene cluster in 19p12.

We investigated the organization, architecture, and evolution of the largest cluster ( approximately 4 Mb) of Krüppel-associated box zinc finger (KRAB-ZNF) genes located in cytogenetic band interval 19p12. A highly integrated physical map ( approximately 700 kb) of overlapping cosmid and BAC clones was developed between genetic STS markers D19S454 and D19S269. Using ZNF91 exon-specific probes to interrogate a detailed EcoRI restriction map of the region, ZNF genes were found to be distributed in a head-to-tail fashion throughout the region with an average density of one ZNF duplicon every 150-180 kb of genomic distance. Sequence analysis of 208,967 bp of this region indicated the presence of two putative ZNF genes: one consisting of a novel member of this gene family (ZNF208) expressed ubiquitously in all tissues examined and the other representing a nonprocessed pseudogene (ZNF209), located 450 kb proximal to ZNF208. Large blocks of ( approximately 25-kb) inverted beta-satellite repeats with a remarkably symmetrical higher order repeat structure were found to bracket the functional ZNF gene. Hybridization analysis using the beta-satellite repeat as a probe indicates that beta-satellite interspersion between ZNF gene cassettes is a general property for 1.5 Mb of the ZNF gene cluster in 19p12. Both molecular clock data as well as a retroposon-mapping molecular fossil approach indicate that this ZNF cluster arose early during primate evolution (approximately 50 million years ago). We propose an evolutionary model in which heteromorphic pericentromeric repeat structures such as the beta satellites have been coopted to accommodate rapid expansion of a large gene family over a short period of evolutionary time. [The sequence data described in this paper have been submitted to GenBank under accession nos. AC003973 and AC004004.]

Alternative Splicing↗
PubMed1998

Concurrent infection due to Shewanella putrefaciens and Mycobacterium marinum acquired at the beach.

Infection with marine bacteria is uncommon. A patient with systemic lupus erythematosus who developed concurrent infection with Shewanella putrefaciens and Mycobacterium marinum (M. marinum) is described. After bathing leg ulcers in sea water, severe cellulitis of the left leg with necrotic areas and extensive bullae developed. Infection due to S. putrefaciens was confirmed and a long course of hospitalization, oral ciprofloxacin and skin grafting was required. During hospitalization subcutaneous nodules developed on the other leg. Biopsy revealed acid-fast bacilli and culture grew M. marinum. These lesions responded to rifampicin and cotrimoxazole. Patients with leg ulcers, peripheral vascular disease, diabetes, or receiving immunosuppressive drugs may acquire unusual infections after salt water exposure.

Aged↗
PubMed1996

Physical mapping of receptor type protein tyrosine phosphatase sigma (PTPRS) to human chromosome 19p13.3.

Receptor type protein tyrosine phosphatase sigma (PTPRS), a member of a subfamily of receptor type protein tyrosine phosphatases, has been mapped to human chromosome 19p13.3 using fluorescence in situ hybridization (FISH) analysis. Hybridization analysis of chromosome 19 library cosmids has revealed several positive clones that are part of a contig located in the same region. The location of this contig was verified since one of the cosmid clones is anchored to a high-resolution FISH map of human chromosome 19p. In addition, the location of this gene relative to previously mapped proximal markers reveals a new point in the human-mouse synteny map by extending the mouse chromosome 17 synteny region in the telomeric direction.

Animals↗
PubMed1996

The use of a modular skills center for the maintenance of laparoscopic skills.

BACKGROUND: A reliable method supplying graduated experience and practice is needed to develop and refine laparoscopic skills. The laparoscopic surgeon, like the microvascular surgeon, must have ongoing training to refine and maintain his or her skills. METHODS: The authors describe a new modular training unit. The unit consists of a box with a built-in television camera, a light source, and a rotating platform. A videotape recorder with a timing device documents the actual "operating time" required for the various exercises. The first phase of training consists of a basic skills board. This initial phase enhances the use of dominant and nondominant hand motor activity. RESULTS: The surgeon then progresses to lifelike models (biliary, suturing, hernia, gynecologic) to simulate the human operative setting. Ten surgeons spent 5 h each working with the module. The specific exercises were recorded and timed. Their progress is described. CONCLUSIONS: The modular laparoscopic skills center is an integral part of any laparoscopic educational program. It facilitates the acquisition and maintenance of laparoscopic skills.

Adult↗
PubMed1995

A 30-Mb metric fluorescence in situ hybridization map of human chromosome 19q.

A high-resolution metric physical map of chromosome 19q has been constructed by fluorescence in situ hybridization. The map locates 136 cosmid reference points that span 30 Mb. The reference points are sequentially ordered from centromere to telomere, and the distance between neighboring cosmids is known from 240 partially overlapping, redundant estimates of genomic distances in kilobases separating pairs of cosmids. The average spacing between cosmid reference points is 220 kb, with over 75% of intervals less than 300 kb. Eighty-four genes and polymorphic markers have been assigned to mapped cosmids. The information on order and genomic distances separating pairs of cosmids, both key elements for building physical maps, has furthered the construction and integration of the genetic and physical maps of chromosome 19.

Chromosome Mapping↗
PubMed1995

Characterization of a promoter for gamma-glutamyl transpeptidase activated in rat liver in response to aflatoxin B1 and ethoxyquin.

gamma-Glutamyl transpeptidase (GGT) is normally absent from adult rat hepatocytes but is induced by a range of xenobiotics, including carcinogens and chemoprotective agents. As many as six mRNA species for this enzyme have been described in both rat and mouse, with various degrees of tissue specificity. These originate from one gene and have separate promoters within alternative 5' untranslated sequences. By using a cDNA-derived sequence specific for GGT mRNA III to screen a rat genomic library, a clone that contains the promoter region for this mRNA was isolated and characterized. The transcriptional start site lay some 3.5 kb upstream from that already characterized for mRNA II in rat kidney. Luciferase activity was obtained after transfection of rat hepatoma-derived cell lines with constructs containing the putative promoter III fused to a luc reporter. Although this promoter lacks a TATA box, a sequence close to the start site that binds the transcription factor TFIID in vitro was identified. By using PCR techniques, mRNA III (homologous to both mouse III and IV) and an mRNA (IV) with homology to VI in mouse were found in ethoxyquin- and aflatoxin B1-treated rat liver and kidney as well as in a hepatoma-derived cell line. No evidence was found for a product homologous to mRNA from promoter V described in the mouse.

Aflatoxin B1↗
PubMed1995

An integrated metric physical map of human chromosome 19.

A metric physical map of human chromosome 19 has been generated. The foundation of the map is sets of overlapping cosmids (contigs) generated by automated fingerprinting spanning over 95% of the euchromatin, about 50 megabases (Mb). Distances between selected cosmid clones were estimated using fluorescence in situ hybridization in sperm pronuclei, providing both order and distance between contigs. An average inter-marker separation of 230 kb has been obtained across the non-centromeric portion of the chromosome. Various types of larger insert clones were used to span gaps between contigs. Currently, the map consists of 51 'islands' containing multiple clone types, whose size, order and relative distance are known. Over 450 genes, genetic markers, sequence tagged sites (STSs), anonymous cDNAs, and other markers have been localized. In addition, EcoRI restriction maps have been generated for > 41 Mb (approximately 83%) of the chromosome.

Base Sequence↗
PubMed1995

The laparoscopic learning curve.

To characterize the learning curve for laparoscopic cholecystectomy, we compared the first 47 cases (group A), which were performed by two senior attending surgeons who assisted each other when the procedure was introduced into clinical practice (1990-1991), with the first 46 cases (group R) performed by two surgical chief residents who were assisted by members of the teaching faculty in 1992-1993. The patient groups were comparable in terms of age, sex, and anesthetic class, but pathologically proven acute cholecystitis was more common in group R (33% vs. 9%; p < 0.005). To analyze operative procedures and outcomes, we compared operative time, frequency of successful operative cholangiography (attempted in all cases), frequency of conversion to open cholecystectomy, major complication rate, and days of postoperative stay for all patients and for those without complications. Of these parameters, only operative time for nonacute cases differed significantly between the groups (144 min for group A vs. 114 min for group R; p < 0.05). Complications in group A included one ductal injury and one case of postoperative pancreatitis; group R had one ductal injury and two cases of postoperative bleeding. We conclude that (a) the learning curve has similar structure for senior surgeons and resident trainees; and (b) the resident learning curve is not hazardous when teaching assistants are trained in the procedure, which has implications for safe instruction and proctoring of residents and staff.

Acute Disease↗
PubMed1994

Granular cell tumor of the biliary system.

Granular cell tumors (GCT) are rare benign neoplasms of Schwann cell origin which have been found in virtually every location in the body. Their location in the biliary system is unusual, and typically occurs in black females during the fourth decade of life. Forty-eight cases have been reported since 1952. We present two patients treated for obstructive jaundice caused by GCT of the extrahepatic biliary tree. The literature on biliary GCT is reviewed and their management is outlined. Local excision with Roux-y-hepaticojejunostomy was performed in one patient with GCT obstructing the common bile duct at the level of the cystic duct. Pancreaticoduodenectomy was performed on one patient for GCT of the common bile duct involving the ampulla and adjacent pancreas. GCT of the extrahepatic biliary system are rare but should be considered in black females who present with obstructive jaundice in the fourth decade of life. Local excision with cholecystectomy and reconstruction of the biliary remnant is indicated. Primary biliary anastomosis is desired but choledochojejunostomy or hepaticojejunostomy may be necessary. Rarely, pancreaticoduodenectomy may be indicated in GCT of the distal common bile duct.

Adult↗
PubMed1994

Human chromosome 19p: a fluorescence in situ hybridization map with genomic distance estimates for 79 intervals spanning 20 Mb.

A physical map of human chromosome 19p has been constructed by fluorescence in situ hybridization of cosmids to metaphase chromosomes and sperm pronuclear interphases. The map spans approximately 20 Mb and was generated with 141 multiple, partially overlapping estimates of genomic distances for 79 intervals separating 80 sequentially ordered cosmid reference points. The average distance separating pairs of cosmids was 250 kb, with a range from 50 to 700 kb; 75% of the intervals were estimated to be less than or equal to 300 kb and only 8 intervals were between 500 and 700 kb. Cosmids positive for 33 genes or gene families and 5 polymorphic markers were included among the mapped elements. The fluorescence in situ hybridization map will be useful for furthering the integration of the physical and genetic maps of 19p and for placing newly identified markers within a few hundred kb of their neighbors.

Analysis of Variance↗
PubMed1994

Chromosomal damage in sperm of patients surviving Hodgkin's disease following MOPP (nitrogen mustard, vincristine, procarbazine, and prednisone) therapy with and without radiotherapy.

Following fusion with hamster eggs, human sperm chromosomes from six Hodgkin's disease patients were analyzed to determine the genotoxic effects of therapy. Each patient had received two to six cycles of MOPP (nitrogen mustard, vincristine, procarbazine, and prednisone), with or without radiotherapy, from 3 to 20 years before the study. A total of 571 cells from the six patients were analyzed; 9.8% of the cells had structural aberrations, and 1.6% were hyperhaploid. Analysis of 5998 metaphases from a control group of 24 male donors revealed only 6.9% of cells with structural aberrations and 0.8% aneuploidy. The increase in hyperhaploidy in the patients was statistically significant. Thus, results of this study suggest that the MOPP regimen, with or without radiotherapy, is capable of causing chromosome abnormalities in the sperm of Hodgkin's disease patients.

Adolescent↗
PubMed1994

The laparoscopic hernia trainer. The role of a life-like trainer in laparoendoscopic education.

The safe and effective performance of laparoscopic inguinal hernia repair requires a working knowledge of pre-peritoneal anatomy. Most surgeons are unfamiliar with the retro-peritoneal view of the groin. A model has been developed which allows surgeons to learn pre-peritoneal anatomy, to practice laparoscopic inguinal herniorrhaphy and to assess their repairs. This model is a valuable laparoendoscopic educational tool.

General Surgery↗
PubMed1994

Laparoscopic cholecystectomy in the first trimester of pregnancy.

Symptomatic biliary tract disease in the pregnant patient has always been problematical. The advent and widespread application of laparoscopic cholecystectomy has led to a re-evaluation of the role of surgery in this clinical situation. We report on the use of laparoscopic cholecystectomy on a patient in the first trimester of pregnancy.

Acute Disease↗
PubMed1993

Laparoscopic excision of a mesenteric cyst.

Benign abdominal cystic tumors are rare. They include retroperitoneal, mesenteric, and omental cysts. Most of these lesions present with vague abdominal pain and nausea. Less commonly they will present with bowel obstruction due to external compression. The diagnosis of these tumors is by abdominal ultrasound or computed tomography. Surgical enucleation is the treatment of choice. Laparoscopic surgical techniques are replacing or complimenting open abdominal surgical procedures. As the indications for these techniques increase, newer applications will arise. Presented here is a case of laparoscopic excision of a mesenteric cyst.

Adult↗
PubMed1992

Spatial distribution of sperm-derived chromatin in zygotes determined by fluorescence in situ hybridization.

Fluorescence in situ hybridization was used to determine the spatial distribution of chromatin in zygote pronuclei. A hybrid system involving golden hamster eggs and individual human sperm permitted use of DNA probes specific for the entire human chromosome 4, for the heterochromatic region on the long arm of the human Y chromosome and for unique DNA sequences on human chromosome 19. Chromosome 4 occupied a circumscribed domain in the pronuclei, similar to findings in somatic interphases. Unlike the situation in somatic interphases, the Y heterochromatin was extended throughout the first cell cycle. Pronuclear chromatin was extended 3- to 4-fold compared to somatic interphase chromatin. The extended pronuclear chromatin conformation is likely to affect a zygote's susceptibility to environmental hazards.

Animals↗
PubMed1992

Order and genomic distances among members of the carcinoembryonic antigen (CEA) gene family determined by fluorescence in situ hybridization.

Fluorescence in situ hybridization was used to establish the order of, and to estimate genomic distances among, members of the carcinoembryonic antigen (CEA) and pregnancy-specific glycoprotein (PSG) subgroups on chromosome 19. Fluorescence in situ hybridization to metaphase chromosomes localized the PSG subgroup telomeric to the CEA subgroup. Cosmid clones containing sequences for individual genes in the CEA and PSG subgroups were also hybridized to human sperm pronuclear and somatic interphase nuclear chromatin targets. The mapping results lead to the gene order cen-CGM7-CEA-NCA-CGM1-BGP-CGM9-CGM8-PSG-te l. The genomic distances between selected pairs of gene family members were estimated from the physical distances between hybridization sites measured in pronuclei. The CEA-PSG gene family region is estimated to span 1.1 to 1.2 Mb.

Carcinoembryonic Antigen↗
PubMed1991

DNA sequence mapping by fluorescence in situ hybridization.

Various types of DNA probes, such as total genomic DNA, repetitive sequences, unique sequences, and composites of chromosome-specific DNA probes, can be used with fluorescence in situ hybridization (FISH) techniques to address research questions having to do with localization, mapping, and distribution of DNA in situ. FISH involves the formation of a heteroduplex between such DNA probes and chromatin targets on a microscope slide, which can be visualized with fluorescent reporter molecules. Three chromatin targets--metaphase chromosomes, somatic interphases, and zygote interphases--offer increasingly extended states of chromatin which can be strategically selected, individually or in combination, to address specific research questions of interest.

Chromosome Mapping↗