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Biomedical subjects

J A Kant

Publications and source records attributed to J A Kant.

At least 19 recordsLinked to original sources
PubMed2002

Novel cationic trypsinogen (PRSS1) N29T and R122C mutations cause autosomal dominant hereditary pancreatitis.

Hereditary pancreatitis (HP) is usually caused by mutations in the cationic trypsinogen (PRSS1) gene, especially R122H or N29I. We sequenced the PRSS1 gene in the proband of families without these common mutations. Novel R122C and N29T mutations were detected in independent families that segregated with the disease in an autosomal dominant fashion. The R122C mutation eliminates the arginine autolysis site as with R122H mutations. The N29T mutation may also enhance intrapancreatic trypsin activity as has been demonstrated in vitro. Identification of these new mutations requires special attention as commonly used detection methods may fail.

Adult↗
PubMed2001

Effect of chronic denervation and denervation-reinnervation on cytoplasmic creatine kinase transcript accumulation.

The extensor digitorum longus (EDL) and soleus muscles of adult mice were chronically denervated or denervated and allowed to reinnervate. Muscles were evaluated 1, 5, 14, 21, and 52 days after sciaticectomy. In terms of weight loss, myofiber atrophy, degeneration, and fibrosis, the soleus muscle was more affected than the EDL by chronic denervation. Fifty-two days after chronic denervation, the number of molecules of MCK/ng total RNA in both muscles (determined with competitive PCR) decreased, with the soleus muscle being more affected. At that stage, BCK mRNA levels in the denervated soleus were unchanged, but they were increased (>50%) in the EDL. Reinnervation restored MCK transcript accumulation in the EDL, whereas, in the soleus MCK, transcripts exceeded control values by 57%, approaching levels in the reinnervated EDL. Despite restoration of MCK mRNA levels, the number of molecules of BCK mRNA/ng total RNA was four- to fivefold higher in reinnervated versus control muscles, suggesting that the genes encoding the CK mRNAs are not coordinately regulated in adult muscle. The role of denervation induced, fiber type changes in regulating CK mRNA accumulation has been evaluated. Electron microscopic analyses have established that fibrosis is not a factor that determines BCK mRNA levels in the chronically denervated or denervated-reinnervated muscles. CK isozyme analyses support the hypothesis that a greater proportion of BCK mRNA found in 52 day chronically denervated and denervated-reinnervated muscles is produced in myofibers vs. nonmuscle cells than in control muscles.

Animals↗
PubMed2001

Genetic testing in acute and chronic pancreatitis.

Hereditary pancreatitis (HP) is clinically indistinguishable from pancreatitis with other causes. Patients with HP have an increased chance of developing pancreatitis. Mutations in the cationic trypsinogen gene appear to cause most HP, although there is evidence for mild genetic heterogeneity with defects in other genes. Trypsin stabilization and protection from autolysis appear to play a central role in the pathogenesis of pancreatitis. The role of mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) as well as the pancreatic secretory trypsin inhibitor (PSTI) in patients with pancreatitis is intriguing but as yet incompletely understood. Genetic testing may help to identify and manage patients with HP. Healthcare professionals should understand the elements necessary for obtaining informed consent for patients undergoing these tests, the limits in interpreting test results, and the psychosocial issues that may arise from genetic testing.

Acute Disease↗
PubMed2001

A tale of two systems: Pathology resident recruitment in and out of the National Resident Matching Program.

The recruitment of most first-year pathology residents currently occurs via 2 systems: the National Resident Matching Program (NRMP), known as the Match, and an underground Out-of-Match process. Out-of-Match recruitment is not a sanctioned option for American medical school seniors. Recent declines in American seniors choosing pathology has intensified pressures to recruit good international medical graduates (IMGs). Pressures by programs on IMGs and by IMGs on programs result in the Out-of-Match recruitment of many IMGs who initially enroll in the NRMP. IMGs may be offered unsolicited Out-of-Match positions with a decision deadline even though they are still interviewing. Some are told if they decline an offer, they will not be ranked by that program in the NRMP process. To enhance apparent recruitment success, programs also feel pressured to participate in the Out-of-Match process, as well as offer positions before they have interviewed all applicants. Coercion of applicants and programs contravenes the spirit of the NRMP, compromises the ability of applicants and programs to best match needs, taints constructive interactions among program directors, and does not enhance pathology's image among applicants or in the broader medical community.

Career Choice↗
PubMed2000

Hepatitis C virus quantitation: optimization of strategies for detecting low-level viremia.

A long-term assessment of quantitative hepatitis C virus (HCV) testing was performed at the University of Pittsburgh Medical Center. The Quantiplex HCV RNA 2.0 branched-chain DNA (bDNA) assay (Bayer Diagnostics) for hepatitis C viral load determination was used to test 3,471 specimens. bDNA-negative samples were also tested by an in-house qualitative reverse transcriptase (RT)-PCR assay with a measured sensitivity of fewer than 100 HCV genome equivalents per milliliter. Of 1,239 bDNA-negative specimens, 74.1% were negative and 25.9% were positive by RT-PCR, indicating the presence of viremia in a significant proportion of bDNA-negative samples. We discuss the medical and economic implications of these results and propose two alternatives for clinical laboratories to consider in approaching quantitative HCV testing. For laboratories able to perform a sensitive RT-PCR assay for </=40% of the bDNA test cost, prescreening bDNA requests by RT-PCR may be the most cost-effective approach.

DNA, Viral↗
PubMed1999

Creatine kinase transcript accumulation: effect of nerve during muscle development.

To determine the role of the nerve in regulating the accumulation of cytoplasmic creatine kinase (CK) mRNAs in hindleg muscles of the developing mouse, the lumbosacral spinal cords of 14-day gestation mice (E14) were laser ablated, and the accumulation of muscle CK (MCK) and brain CK (BCK) mRNAs was evaluated just prior to birth with in situ hybridization. Numbers of molecules of each of these transcripts/ng total RNA in the soleus and extensor digitorum longus (EDL) muscles were determined with competitive PCR and compared to transcripts found in innervated crural muscles. Data suggest that: 1) the level of BCK mRNA accumulation in innervated hindlimb muscles peaks at E16.5 and remains at fetal levels until the second month postnatal, when it falls to the level found in the adult. Given that MCK transcripts meet or exceed adult levels by day 28 postnatal, the "down-regulation" of the BCK gene and the "up-regulation" of the MCK gene are not tightly coupled; 2) the developmental switch from BCK to MCK, as the dominant cytoplasmic CK mRNA, occurs in innervated and aneural leg muscles between E14 and E16.5, indicating this switch is not nerve dependent; 3) the absence of innervation has no effect on BCK mRNA accumulation. MCK transcripts/ng total RNA continue to increase in aneural muscle throughout the late fetal period, but from E16.5-E19.5 the MCK transcript levels in aneural muscles become progressively lower than in age-matched innervated muscles. Thus, the accumulation of the muscle specific cytoplasmic CK, but not BCK, transcripts is affected by the absence of innervation during the fetal period. Dev Dyn 1999;215:285-296.

Age Factors↗
PubMed1999

Molecular diagnostics on microfabricated electrophoretic devices: from slab gel- to capillary- to microchip-based assays for T- and B-cell lymphoproliferative disorders.

BACKGROUND: Current methods for molecular-based diagnosis of disease rely heavily on modern molecular biology techniques for interrogating the genome for aberrant DNA sequences. These techniques typically include amplification of the target DNA sequences followed by separation of the amplified fragments by slab gel electrophoresis. As a result of the labor-intensive, time-consuming nature of slab gel electrophoresis, alternative electrophoretic formats have been developed in the form of capillary electrophoresis and, more recently, multichannel microchip electrophoresis. METHODS: Capillary electrophoresis was explored as an alternative to slab gel electrophoresis for the analysis of PCR-amplified products indicative of T- and B-cell malignancies as a means of defining the elements for silica microchip-based diagnosis. Capillary-based separations were replicated on electrophoretic microchips. RESULTS: The microchip-based electrophoretic separation effectively resolved PCR-amplified fragments from the variable region of the T-cell receptor-gamma gene (150-250 bp range) and the immunoglobulin heavy chain gene (80-140 bp range), yielding diagnostically relevant information regarding the presence of clonal DNA populations. Although hydroxyethylcellulose provided adequate separation power, the need for a coated microchannel for effective resolution necessitated additional preparative steps. In addition, preliminary data are shown indicating that polyvinylpyrrolidone may provide an adequate matrix without the need for microchannel coating. CONCLUSIONS: Separation of B- and T-cell gene rearrangement PCR products on microchips provides diagnostic information in dramatically reduced time (160 s vs 2.5 h) with no loss of diagnostic capacity when compared with current methodologies. As illustrated, this technology and methodology holds great potential for extrapolation to the abundance of similar molecular biology-based techniques.

DNA, Neoplasm↗
PubMed1999

Rapid diagnosis of herpes simplex encephalitis using microchip electrophoresis of PCR products.

BACKGROUND: Herpes simplex virus (HSV) is the most common cause of acute sporadic encephalitis in the United States. PCR of DNA extracted from cerebrospinal fluid (CSF) allows for reliable diagnosis of herpes simplex encephalitis (HSE). A faster turnaround time for HSE testing would improve patient management and lead to better outcomes. The aims of this study, therefore, were to develop a microchip-based electrophoretic method for rapid detection of HSV PCR products, and to compare the performance characteristics of liquid hybridization/gel retardation as an established clinical PCR product detection method with the new microchip-based method. METHODS: The study examined archival DNA from 33 selected CSF specimens submitted for HSV PCR testing to the clinical laboratory. One aliquot of the HSV PCR product was analyzed by liquid hybridization/gel retardation analysis, and a second PCR aliquot was analyzed directly with a microchip capillary electrophoresis system using an instrument built in-house. PCR samples were introduced directly into the microchip without a desalting step by use of a novel fluidic interface. Channel surfaces on the glass microchip were silanized, followed by derivatization with polyvinylpyrrolidone. RESULTS: Of the 33 CSF specimens tested by liquid hybridization analysis of HSV PCR products, 10 tested positive for HSV DNA, 2 gave a weakly positive result, and 21 tested negative. Total analysis time for detection of HSV DNA by gel retardation assay was 18 h. Microchip electrophoresis provided identical results in <110 s/sample, achieving 100% sensitivity and specificity compared with the established method. CONCLUSIONS: Microchip-based electrophoresis can rapidly and accurately separate HSV PCR products, giving results identical to those obtained by liquid hybridization but with substantially decreased turnaround time. Clinical implementation of the new method will help to improve patient management and outcomes.

Computers↗
PubMed1998

Prenatal identification of mos 45,X/46,X,+mar in a normal male baby by cytogenetic and molecular analysis.

We report a case of mos 45,X/46,X,+mar, diagnosed prenatally by amniocentesis, whose physical examination, including external and internal organs, along with serum testosterone values were normal five years after delivery. The mosaic karyotype was seen in 146 of 240 cells examined (amniotic fluid cells, 110/65; placental chorionic villi: 5/4; cord blood, 21/81; cultured skin fibroblasts, 10/90) from 386 metaphases, and the marker chromosome appeared as a small non-fluorescent acrocentric chromosome. All autosomes appeared normal, and no normal Y chromosome could be demonstrated. Analysis of 26 Y-chromosome loci by molecular techniques such as PCR, Southern analysis using multiple Y-specific DNA probes, and Hae III restriction endonuclease assessment of male-specific repeated DNA in the heterochromatic region of the Y chromosome, and fluorescence in situ hybridization (FISH), revealed the marker was derived from a Y chromosome including p terminal to q11.23, and paracentric inversion in the remaining Y long arm. The formation of testes can be considered as existence of SRY (sex-determining region of Y) as a testis-determining factor. The present report illustrates the importance of FISH and molecular techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.

Adult↗
PubMed1998

Seminoma in a postmenopausal woman with a Y;15 translocation in peripheral blood lymphocytes and a t(Y;15)/45,X Turner mosaic pattern in skin fibroblasts.

We report an unusual case of a 55 year old Japanese woman with a seminoma but relatively normal menses. The patient was a phenotypic female with late onset menarche (18 years of age), who was amenorrhoeic for the first year, followed by menses of one to three days' slight flow with dysmenorrhoea, but an otherwise normal menstrual history. A typical seminoma was removed from the left adnexal region and an immature testis was identified separately as an associated right adnexal mass. Repeated karyotypic studies on peripheral blood lymphocyte cultures showed only 46,X,-Y,t(Y;15)(q12;p13). Cytogenetic examination of the patient's younger brother, who had fathered three healthy children, showed an identical karyotype. Mosaicism of 46,X,-Y,t(Y;15)(q12;p13)/45,X cell lines was found in skin samples from the patient's elbow and genital regions, although there were no clinical stigmata of Turner syndrome. An androgen receptor binding assay of cultured genital skin fibroblasts was negative. Molecular analysis using Southern blot hybridisation, PCR, and direct DNA sequencing showed that neither the patient nor her brother had a detectable deletion or other abnormalities of Y chromosome sequences, including the SRY (sex determining region of the Y chromosome) gene sequence. These findings suggest that Turner mosaicism of the 45,X cell line may have contributed to this atypical presentation in an XY female, although we cannot exclude abnormalities of other genes related to sex differentiation.

Blotting, Southern↗
PubMed1997

Hepatosplenic gammadelta T-cell lymphoma: ultrastructural, immunophenotypic, and functional evidence for cytotoxic T lymphocyte differentiation.

Hepatosplenic gammadelta T cell lymphoma (TCL) is a rare, aggressive subset of peripheral TCL that presents with hepatosplenomegaly and cytopenias. Detailed clinicopathological, ultrastructural, and cytogenetic analyses of these lymphomas are limited; functional characteristics of these lymphomas are unknown. We have undertaken a clinicopathological, immunophenotypic, ultrastructural, cytogenetic, and functional analysis of three hepatosplenic gammadelta TCLs. All patients presented with massive hepatosplenomegaly and anemia, thrombocytopenia, or severe neutropenia; terminal blastlike transformation occurred in one patient. Combination chemotherapy had no response in two patients, but induced complete remission in one. gammadelta T cell receptor (TCR) expression and clonal TCRdelta gene rearrangements were documented in each case. Two different subsets of gammadelta TCL were identified based on delta chain variable region usage; two lymphomas were Vdelta1+, whereas the third was negative for both Vdelta1 and Vdelta2. Cytogenetic analysis was performed on two lymphomas; isochromosome 7q and probable trisomy 8 was shown in one of the Vdelta1+ lymphomas, whereas the Vdelta1 negative lymphoma had 14p+ with t(1;14)(q21;p13). NK cell-associated antigens (CD11c, CD16, or CD56) and cytotoxic T lymphocyte (CTL) effector proteins (perforin, granzyme B, TIA-1, and Fas ligand) were expressed by each lymphoma; dense core cytolytic granules were observed by electron microscopy in both lymphomas studied. Functional studies performed in two cases showed TCR-mediated cytolysis of P815 x 2 FcR+ cells induced by anti-CD3 in a redirected cytolysis assay in one of the CD56+, Vdelta1+ lymphomas, whereas IFNgamma secretion was induced by anti-CD3 in the CD56-, Vdelta1 negative lymphoma. These studies show that hepatosplenic gammadelta TCLs have CTL differentiation, retain functional activity in vitro, and are derived from at least two gammadelta T cell subsets.

Adolescent↗
PubMed1997

Primary low-grade T-helper cell testicular lymphoma.

Non-Hodgkin's lymphoma is the most common primary testicular neoplasm of older men but is rare in young men. The vast majority of primary testicular lymphomas are intermediate- to high-grade lymphomas. Peripheral T-cell lymphomas of the testes are rare; most are large cell lymphomas. We describe an unusual case of a primary small lymphocytic, CD4+, peripheral T-cell lymphoma that presented as a Staphylococcus aureus scrotal abscess in a 30-year-old male. Clonal rearrangement of the T-cell receptor beta gene was demonstrated by Southern analysis. To our knowledge, low-grade, peripheral T-cell lymphoma of the testes has not been previously reported.

Adult↗
PubMed1995

DNA typing of the human MN and Ss blood group antigens in amniotic fluid and following massive transfusion.

Although red blood cell (RBC) antigen typing by agglutination is generally useful, several situations exist where this approach is difficult or impossible. For example, following a massive transfusion, a patient's residual RBCs are mixed with transfused normal donor RBCs. In this case, typing by hemagglutination primarily detects the antigens on the heterogeneous population of transfused RBCs. Agglutination testing is also of limited use for determining the phenotype of a fetus at risk for hemolytic disease of the newborn because fetal RBCs must be obtained by periumbilical blood sampling. Determining the genotype of an individual by analyzing genomic DNA isolated from peripheral blood nucleated cells or amniocytes is an alternative approach for determining the RBC antigen type. In this report, the allele specific polymerase chain reaction (AS-PCR) was used to identify the alleles at the MN and Ss loci that encode the corresponding antigens on glycophorin A (GPA) and glycophorin B (GPB), respectively. This method was used to type these alleles in peripheral blood samples obtained from normal individuals and from patients following massive transfusion. Of 23 peripheral blood specimens analyzed, all were correctly typed by this method. The allele specific polymerase chain reaction was also used to determine these alleles using amniotic fluid samples. Of 11 amniotic fluid specimens analyzed, 8 were correctly typed at both loci. Mistyping of three amniotic fluid specimens was explained by possible maternal blood contamination.

Amniotic Fluid↗