PubMed Health⌕ Search

Biomedical subjects

M Prochazka

Publications and source records attributed to M Prochazka.

At least 55 records · Page 3Linked to original sources
PubMed1993

Islet cell autoantigen 69 kD (ICA69). Molecular cloning and characterization of a novel diabetes-associated autoantigen.

We have identified a novel 69-kD peptide autoantigen (ICA69) associated with insulin-dependent diabetes mellitus (IDDM) by screening a human islet lambda gt11 cDNA expression library with cytoplasmic islet cell antibody positive sera from relatives of IDDM patients who progressed to the overt disease. The deduced open reading frame of the ICA69 cDNA predicts a 483-amino acid protein. ICA69 shows no nucleotide or amino acid sequence relation to any known sequence in GenBank, except for two short regions of similarity with BSA. The ICA69 cDNA probe hybridizes with a 2-kb mRNA in poly(A+) RNA from human pancreas, brain, heart, thyroid, and kidney, but not with skeletal muscle, placenta, spleen, or ovary. Expression of ICA69 was also detected in beta cells and cell lines, as well as in tumoral tissue of islet cell origin. The native ICA69 molecule migrates to 69 kD in SDS-PAGE as detected with specific antibodies. Serum samples from relatives of IDDM patients specifically reacted with affinity-purified recombinant ICA69 on Western blotting. The structural gene for ICA69 was designated ICA1. A homologue in the mouse, designated Ica-1 was mapped to the proximal end of chromosome 6 (within 6 cM of the Met protooncogene). ICA69 adds a novel autoantigen to the family of identified islet target molecules, and by the manner of its identification and characterization large amounts of antigen are available for development of quantitative, convenient predictive assays for autoantibodies and analysis of the role of this molecule in diabetes autoimmunity, as well as its physiologic function.

Amino Acid Sequence↗
PubMed1993

Linkage of chromosomal markers on 4q with a putative gene determining maximal insulin action in Pima Indians.

Insulin action in vivo varies widely in nondiabetic Pima Indians. Not all of this variance is attributable to individual differences in obesity, physical fitness, sex, or age, and after correcting for these co-variates, measures of insulin action aggregate in families. Insulin action at maximally stimulating insulin concentrations has a trimodal frequency distribution, particularly among obese individuals. This is consistent with the hypothesis that a codominantly inherited autosomal gene, unrelated to obesity, determines MaxM in the population. Preliminary sib-pair linkage analyses indicated the possibility of linkage between MaxM and the GYPA/B locus (encoding the MNSs red cell surface antigens) on chromosome 4q. To confirm and extend these findings, 10 additional loci on 4q were typed in 123 siblings and many of their parents from 46 nuclear families. The results indicate significant (P < 0.001) linkage of the FABP2 and ANX5 loci on 4q with MaxM, and of FABP2 with fasting insulin concentration. No linkage was found between the 4q markers and obesity. Our findings indicate that a gene on 4q, near the FABP2 and ANX5 loci, contributes to in vivo insulin action in Pima Indians.

Adult↗
PubMed1992

The nonobese diabetic scid mouse: model for spontaneous thymomagenesis associated with immunodeficiency.

Homozygosity for the severe combined immunodeficiency (scid) mutation results in a block in T- and B-lymphocyte development. An unusually high incidence of spontaneous thymic lymphoma development was observed after transfer of this mutation from the C.B-17 congenic strain background onto the diabetes-susceptible nonobese diabetic (NOD) background. Thymomagenesis in the NOD-scid/scid mouse was associated with expression of an NOD mouse-unique endogenous ecotropic murine leukemia provirus locus (Emv-30, mapped to proximal region of chromosome 11) not expressed in the standard substrain NOD/Lt thymus. All tumors exhibited insertions of ecotropic proviruses, whereas only a subset also exhibited proviral integrations of mink cell focus-forming retrovirus. Neither class of retrovirus was associated with consistent integration into genes previously associated with activation of oncogenesis. We propose that the unusual features of T-cell ontogeny characteristic of the NOD inbred strain synergize with the scid-imparted block in thymocyte development, leading to activation of the NOD-unique Emv-30 to initiate thymomagenesis.

Animals↗
PubMed1992

Beta cell expression of endogenous xenotropic retrovirus distinguishes diabetes-susceptible NOD/Lt from resistant NON/Lt mice.

Endogeneous retroviral expression in beta cells is a feature of prediabetes in nonobese diabetic (NOD) mice. The purpose of this study was to characterize the class-specific pattern of retroviral gene expression in NOD/Lt beta cells versus a related, but diabetes-resistant strain, NON/Lt. Electron microscopic comparison of beta cells from both strains indicated low constitutive expression of the intracisternal type A (IAP) retroviral class. However, NOD beta cells, in contrast to NON beta cells, expressed an additional intracisternal retroviral form resembling a type C particle. Antibodies against both IAP and type C were detected in NOD, with the humoral response to type C, but not IAP, preceding decline in beta cell function. RNA was extracted from freshly isolated islets from NOD and NON males. Comparative Northern blot analysis of total type C retroviral gene expression using a gag-pol DNA probe corroborated expression of endogenous type C proviruses in both NOD and NON islet cells and thymus. Use of class-specific retroviral probes identified the class of expressed endogenous retrovirus distinguishing the two inbred strains. The single ecotropic provirus present in both the NOD and NON genome (Emv-30) was not expressed in islets or thymus of either strain. Comparison of endogenous xenotropic provirus content by Southern blot analysis revealed two unique xenotropic loci (Xmv-65, -66) in NOD; 8.4 and 3.0 kb xenotropic envelope (env) RNA transcripts were detected in NOD, but not NON islets and thymus. NON contained three xenotropic loci common to other inbred strains (Xmv-21, -25, and -28). Both strains were partially characterized for content of recombinant (polytropic and modified polytropic) proviruses. IAP RNA expression was common to both NOD and NON islets and hence could not be specifically associated with the unique intracisternal type C particle found in NOD, but not NON beta cells. In conclusion, this study shows that expression of xenotropic type C but not IAP distinguishes retroviral activity in NOD/Lt versus NON/Lt beta cells. The potential pathogenic role of retroviral gene expression in NOD beta cells is discussed.

Animals↗
PubMed1992

NOR/Lt mice: MHC-matched diabetes-resistant control strain for NOD mice.

NOR/Lt is an insulitis-resistant and diabetes-free strain produced from an isolated genetic contamination within an NOD/Lt pedigree line. The albino coat-color phenotype, strain-specific endogenous retroviral profile, and skin graft tests indicated an NOD/Lt x C57BL/KsJ outcross-backcross segregant as the source of the contaminating genome. Analysis of 53 polymorphic DNA, biochemical, and immunologic markers distinguishing NOD/Lt from C57BL/KsJ revealed that 4 chromosomes (chromosomes 2, 4, 11, and 12) in NOR/Lt contained C57BL/KsJ-derived genes. The remaining markers on 14 chromosomes, including the diabetogenic H-2g7 complex on chromosome 17, were of NOD origin. Although completely resistant to cyclophosphamide-induced diabetes, NOR/Lt mice exhibited the same peripheral T-lymphocyte accumulation characteristic of NOD/Lt. Similarly, NOR/Lt peritoneal macrophages exhibited depressed interleukin-1 secretion characteristic of NOD/Lt. In addition to their diabetes resistance, NOR/Lt mice were distinguished from NOD/Lt by exhibiting more robust suppressor T-lymphocyte function. Outcross of NOR/Lt with NOD/Lt to generate heterozygosity at those chromosomal segments, defined by C57BL/KsJ markers in NOR/Lt parentals, did not produce insulitis or diabetes in F1 females. However, these F1 females were sensitive to cyclophosphamide-induced diabetes. In summary, the NOR/Lt strain is an MHC-matched diabetes-resistant control strain for NOD/Lt. Moreover, NOR/Lt will help identify the location and function of a non-MHC gene or genes capable of conferring resistance against insulitis and diabetes.

Animals↗
PubMed1991

Effect of androgen insensitivity on diabetogenesis in db/db male mice with testicular feminization (Tfm).

In C3H mice, a major component of susceptibility to the diabetogenic action of an obesity mutation (diabetes, db) is male gender associated. We tested whether increased male susceptibility was an androgen receptor mediated process. C3H.SW/Lt-derived db/db males were rendered androgen-receptor function-deficient by introducing the testicular feminization (Tfm) mutation of the X-linked androgen receptor gene. The db/db Tfm/Y males (phenotypically female in appearance) developed severe diabetes indistinguishable from that observed in standard db/db X + Y males. Castration of standard C3H.SW/Lt-db/db males (producing mutants with normal androgen receptors but reduced serum testosterone) also failed to block the gender-enhanced susceptibility. In contrast, female db/db littermates exhibited a milder hyperglycemia, and were more resistant to pancreatic beta cell necrosis and islet atrophy than any of the groups of db/db males. Although these data indicated that male-enhanced sensitivity to diabetogenic stress was independent of circulating androgens, the possibility that the gender dimorphism is predicated upon tissue ratios of active estrogens to androgens in glucose-producing tissues such as liver is discussed.

Androgen-Insensitivity Syndrome↗
PubMed1989

A glycerol-3-phosphate dehydrogenase null mutant in BALB/cHeA mice.

A mutation in the BALB/cHeA subline of mice has resulted in loss of the glycerol-3-phosphate dehydrogenase (glycerol-P dehydrogenase) activity in adult tissues. Analysis of F2 offspring segregating for enzyme activity levels and a PvuII restriction fragment length polymorphism in the Gdc-1 gene on Chromosome 15 indicates that the mutation has occurred in or around the structural gene. Southern blot analysis failed to detect any major change due to chromosomal insertion, deletion, or rearrangement of the mutant gene. In vitro measurements of transcription in isolated nuclei failed to detect any difference in transcription between the BALB/cHeA and BALB/cBy strains of mice. However, Northern blot analysis with poly(A+) RNA isolated from brown fat shows that the mutant has about a 50-fold reduction in hybridizable transcripts of altered size. The data suggest that the mutation affected the processing of nuclear transcripts of glycerol-P dehydrogenase. The morphological, physiological, and reproductive characteristics of the mutant mice appear normal. This suggests that alternate pathways of energy metabolism and lipid synthesis exist which obviate the function of glycerol-P dehydrogenase.

Adipose Tissue, Brown↗
PubMed1989

Organic aciduria and butyryl CoA dehydrogenase deficiency in BALB/cByJ mice.

A metabolic screening program of inbred strains of mice has detected a marked organic aciduria in the BALB/cByJ strain. Gas chromatographic and mass spectrometric analysis identified large quantities of n-butyrylglycine plus lesser quantities of ethylmalonic acid. Crosses with the nonexcreting C57BL/6J strain indicate that this condition is inherited as an autosomal recessive trait. Independently from this screening a variant with no detectable enzyme activity of butyryl CoA dehydrogenase (BCD) in liver and kidney of the BALB/cByJ strain but not other BALB/c sublines was discovered. Data from a three-point cross indicated that the null variant maps to the structural locus for the enzyme, Bcd-1, on chromosome 5. The findings indicate that a mutation at or near Bcd-1 in the BALB/cByJ strain resulted in a biochemical abnormality manifest as the BCD deficiency. It is concluded that accumulation of butyryl CoA due to a block in the oxidation of short-chain fatty acids results in an overproduction of organic metabolites leading to the observed organic aciduria. The fact that other BALB/c substrains do not exhibit this abnormality further suggests that this disorder reflects subline divergence within the BALB/c family.

Animals↗
PubMed1989

Genetic control of diabetogenesis in NOD/Lt mice. Development and analysis of congenic stocks.

Genetic outcross and backcross analysis of nonobese diabetic (NOD/Lt) mice with a related but diabetes-resistant strain, nonobese normal (NON/Lt), has demonstrated that susceptibility to insulin-dependent diabetes mellitus is controlled in a recessive fashion by multiple genetic loci, including one (Idd-1s) associated with H-2 on chromosome 17 and another (Idd-2s) associated with Thy-1b/Apoa-1b (formerly Alp-1) on chromosome 9. To analyze the separate pathogenic contributions of Idd-1s and Idd-2s, two distinct congenic stocks of NOD/Lt mice homozygous on chromosomes 17 and 9 for NON/Lt linkage markers for the respective resistance alleles (Idd-1r and Idd-2r) were developed. The recessive nature of Idd-1s was confirmed at the fifth backcross generation in that 83% of females and 29% of males homozygous for NOD H-2 haplotype developed diabetes, whereas no diabetes occurred in any of the mice homozygous or heterozygous for the NON haplotype. However, codominant and recessive MHC-associated susceptibility genes in this congenic stock were indicated by the finding that at least one copy of the NOD/Lt MHC was required for insulitis development. Virtually no insulitis was detected in the pancreases of mice homozygous for NON haplotype at 42 wk of age, whereas heavy generalized insulitis was present in 3 of 19 H-2 heterozygotes and in 7 of 7 diabetic and 3 of 5 nondiabetic mice homozygous for NOD haplotype. Further indication of the presence of MHC-associated codominant and recessive MHC-associated susceptibility genes was the observation that the NOD MHC haplotype correlated in a codominant fashion with a relative increase in the percentage of splenic T-lymphocytes bearing the Ly-2 surface marker. Severe insulitis and concomitant high diabetes incidences occurred in all genotypic classes of congenic mice carrying Thy-1/Apoa-1 linkage markers for either NOD or NON alleles at Idd-2. Molecular analysis indicated that the NON-derived Idd-2r resistance allele had been replaced by recombination with Idd-2s from NOD. Restriction-fragment-length polymorphism analysis of two polymorphic markers proximal to Thy-1, low-density lipoprotein receptor Ldlr and Ets-1, a protooncogene, confirmed a recombinant chromosome 9, because homozygosity for NOD genomic fragments was found centromeric to an NON congenic segment of at least 20 centiMorgans spanning the Thy-1 and Mod-1 loci.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Cocoa: a new mouse model for platelet storage pool deficiency.

We describe genetic, haematological and biochemical properties of a new mouse pigment mutant, cocoa (coa). Cocoa is a recessive mutation located on the centromeric end of chromosome 3 near the Car-2 locus. The mutation causes increased bleeding time accompanied by symptoms of platelet storage pool deficiency (SPD), including decreased platelet serotonin and decreased visibility of dense granules as analysed by electron microscopy of unfixed platelets. Dense granules were visible in normal numbers when platelets were incubated with the fluorescent dye, mepacrine. The intragranular environment, however, was abnormal as indicated by decreased flashing of mepacrine-loaded dense granules after exposure to ultraviolet light. Unlike the previously described seven mouse pigment mutations with SPD in which pigment granules, platelet dense granules and lysosomes are affected, the cocoa mutant had normal secretion of lysosomal enzymes from kidney proximal tubule cells and platelets. The cocoa mutation thus represents an example of a single gene which simultaneously affects melanosomes and platelet dense granules but probably does not affect lysosomes. The results indicate that melanosomes and platelet dense granules share steps in synthesis and/or processing. Cocoa may be a model for cases of human Hermansky-Pudlak syndrome in which functions of melanosomes and platelet dense granules, but not lysosomes, are involved.

Animals↗
PubMed1988

Genetic and environmental control of diabetes induction by multi-dose streptozotocin in two BALB/c substrains.

BALB/cJ male mice were resistant and BALB/cByJ males were susceptible to induction of diabetes by multi-dose streptozotocin (MSz). Although both closely-related BALB/c substrains expressed H-2d haplotype, they could be differentiated by allelic differences at three genetic loci [Qa-2 (Chr 17), Bcd-1 (Chr 5), and Afr-1]. (BALB/cJ X BALB/cByJ)F1 males inherited the BALB/cJ resistance phenotype in a dominant fashion, thereby eliminating the BALB/cJ-expressed Afr-1b (recessive) allele as the susceptibility locus. Backcross of F1 mice to the susceptible BALB/cByJ strain produced a 1:1 segregation of susceptible and resistant (F1-like) phenotypes, suggesting that susceptibility was controlled by a single recessive gene. No linkage was found between the putative susceptibility gene and the mutant BALB/cByJ Qa-2,3 gene linked to the H-2 complex or with the mutant Bcd-1c allele. Since the resistant F1 males expressed low levels of androgen-dependent mouse urinary protein characteristic of the resistant BALB/cJ parental strain, the possibility was discussed that the alleles controlling sensitivity to MSz also controlled tissue sensitivity to endogenous androgens. An environmental effect on phenotype expression was indicated when BALB/cByJ males obtained from a colony free of pneumonia virus of mice (PVM) showed an attenuated rate of response to hyperglycemia induction in comparison to males obtained previously from an enzootically infected colony.

Alleles↗
PubMed1987

Three recessive loci required for insulin-dependent diabetes in nonobese diabetic mice.

A polygenic basis for susceptibility to insulin-dependent diabetes in nonobese diabetic (NOD) mice has been established by outcross to a related inbred strain, nonobese normal (NON). Analysis of first and second backcross progeny has shown that at least three recessive genes are required for development of overt diabetes. One, Idd-1s, is tightly linked to the H-2K locus on chromosome 17; another, Idd-2s, is localized proximal to the Thy-1/Alp-1 cluster on chromosome 9. Segregation of a third, Idd-3s, could be shown in a second backcross. Neither Idd-1s nor Idd-2s could individually be identified as the locus controlling insulitis; leukocytic infiltrates in pancreas were common in most asymptomatic BC1 mice. Both F1 and BC1 mice exhibited the unusually high percentage of splenic T lymphocytes characteristic of NOD, suggesting dominant inheritance of this trait. The polygenic control of diabetogenesis in NOD mice, in which a recessive gene linked to the major histocompatibility complex is but one of several controlling loci, suggests that similar polygenic interactions underlie this type of diabetes in humans.

Animals↗