PubMed Health⌕ Search

Biomedical subjects

R Kofler

Publications and source records attributed to R Kofler.

At least 73 records · Page 4Linked to original sources
PubMed1992

Identification of molecular defects causing congenital adrenal hyperplasia by cloning and differential hybridization of polymerase chain reaction-amplified 21-hydroxylase (CYP21) genes.

Congenital adrenal hyperplasia (CAH), one of the most common autosomal recessive disorders, is caused primarily by defects in the gene encoding steroid 21-hydroxylase, CYP21B. The molecular diagnosis of CAH, important for prenatal diagnosis, carrier detection, and a better understanding of the various clinical CAH forms, is complicated by the close proximity of a highly similar pseudogene, CYP21A, containing (and probably donating, by gene conversion-like events) most of the defects underlying CAH. In this study, we describe an efficient strategy to identify molecular defects causing CAH: polymerase chain reaction-amplified CYP21 loci are cloned and hybridized to a set of oligonucleotides, allowing rapid and allele-specific identification of all known CYP21B mutations relevant to 21-hydroxylase function. Possible new mutations can be identified by subsequent nucleic acid sequencing provided they reside within the cloned CYP21B fragment (from the TATA box to the 8th of the 10 CYP21B gene exons). Using this method, the CYP21B gene mutations of a heterozygous carrier and 25 CAH patients have been identified by oligonucleotide hybridization. All disease haplotypes seem to have been generated by recombinational events involving the CYP21A pseudogene. In 5 individuals, these data were subsequently verified by nucleic acid sequencing. The procedure can be used for diagnostic applications and may facilitate identification of new CYP21B defects.

Adrenal Hyperplasia, Congenital↗
PubMed1992

Frame shift by insertion of 2 basepairs in codon 394 of CYP11B1 causes congenital adrenal hyperplasia due to steroid 11 beta-hydroxylase deficiency.

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder of corticosteroid biosynthesis primarily caused by a deficiency in either of two heme-containing cytochrome P450-enzymes: steroid 21- or 11 beta-hydroxylase (causing approximately 90% and 5-8% of classical CAH cases, respectively). Depending on the patient's gender, the affected enzyme, and the extent of enzymatic dysfunction, symptoms include adrenal hyperplasia, androgen excess, virilization, growth disturbance, and electrolyte imbalance. To define the molecular basis of steroid 11 beta-hydroxylase-deficient CAH, we cloned and sequenced the CYP11B1 gene (encoding 11 beta-hydroxylase) of a female patient afflicted with this disorder. Exon 7 contained a 2-basepair insertion in codon 394, leading to a reading frame shift, multiple incorrect codons, and a premature stop in codon 469, resulting in complete destruction of the enzyme's heme-binding domain. Due to parental consanguinity, this defect was homozygous and, therefore, provides a full molecular explanation for this disease.

Adrenal Hyperplasia, Congenital↗
PubMed1992

R339H and P453S: CYP21 mutations associated with nonclassic steroid 21-hydroxylase deficiency that are not apparent gene conversions.

Steroid 21-hydroxylase deficiency is the most common enzymatic defect causing congenital adrenal hyperplasia, an inherited disorder of cortisol biosynthesis. All mutations thus far characterized that cause this disorder appear to result from recombinations between the gene encoding the enzyme, CYP21B (CYP21), and the adjacent pseudogene, CYP21A (CYP21P). These are either deletions caused by unequal crossing-over during meiosis or apparent transfers of deleterious sequences from CYP21A to CYP21B, a phenomenon termed gene conversion. However, a small percentage of alleles do not carry such a mutation. We analyzed DNA from a patient with the mild, nonclassic form of 21-hydroxylase deficiency, who carried one allele that had no gene conversions detectable by hybridization with oligonucleotide probes. Sequence analysis revealed that this allele carried two missense mutations, R339H and P453S, neither of which has been previously observed in CYP21A or CYP21B. Each of these mutations was introduced into CYP21 cDNA which was then expressed in COS1 cells using a vaccinia virus system. Each mutation reduced the ability of the enzyme to 21-hydroxylate 17-hydroxyprogesterone to 50% of normal and the ability to metabolize progesterone to 20% of normal. Thus, each of these mutations represents a potential nonclassic 21-hydroxylase deficiency allele that is not the result of an apparent gene conversion.

Adrenal Hyperplasia, Congenital↗
PubMed1991

An autosomal recessive gene that delays expression of lupus in BXSB mice.

We report the generation and serologic, cellular, histologic, and genetic characteristics of a BXSB/MpJScr substrain, termed BXSB/MpJScr-ll/ll, that has lost early-life male lupus disease. Classic genetic analysis suggested that delayed disease expression results from the action of a single autosomal recessive gene. This putative gene, referred to as ll (long-lived), causes a significant delay in expression of autoimmune serology (total serum IgG and anti-nuclear antibodies levels), monocytosis, and of immune complex-mediated histopathologic changes such as glomerulonephritis, arteritis, and myocardial infarction. Presumably as a consequence of the delayed immunopathology male BXSB/MpJScr-ll/ll mice live three to four times longer than regular BXSB/MpJScr. This strain might be useful for analysis of single genes responsible for severe autoimmune disease expression.

Animals↗
PubMed1991

Evolutionary relationship between human and mouse immunoglobulin kappa light chain variable region genes.

Similar to the Igh-V multigene family, the human or mouse Igk-V repertoire is a distorted continuum of homologous genes that may be grouped into families displaying greater than 80% nucleic acid sequence similarity among their members. Systematic interspecies sequence comparisons reveal that most human Igk-V gene families exhibit clear homology to mouse Igk-V families (sequence similarity generally greater than 74%). A hypothetical phylogenetic tree of Igk-V genes predicts that a minimum of seven Igk-V genes/families predate mammalian radiation. In two cases, several interrelated mouse Igk-V families exhibit phylogenetic equidistance with just one human Igk-V family, implying a more pronounced divergence for the elevated number of Igk-V gene families in the mouse. Mouse-human Igk-V comparisons, moreover, illustrate how expansion, contraction, and perhaps deletion of Igk-V gene families shape the Igk-V repertoire during mammalian evolution.

Animals↗
PubMed1991

[Clinical epidemiologic data of malignant melanoma based on 1,368 patients of the Graz University Dermatology Clinic (1970-1989)].

Epidemiological and histological data of 1368 patients with invasive malignant melanoma treated at the Department of Dermatology between 1970 and 1989 were analysed retrospectively. Frequency of melanoma increased from 103 cases between 1970 and 1974 to 593 between 1985 and 1989. The male/female ratio was 1/1.5 and did not change during the study period. Mean age of patients at the time of primary operation was 56.1 years and was approximately the same for males and females (males 55.8, females 56.3 years). The predominant site was the trunk in males (58.7 per cent) and the lower leg in females (41.6 per cent). There was a relative increase of melanomas of the back in males and the lower leg in females at the expense of melanomas of the face. The Breslow index was significantly higher in males than in females. In patients older than 69 years, the proportion of thick melanomas was above average. During the study period, the frequency of thick melanomas (greater than 1.5 mm) showed an encouraging decrease in both sexes. In 1989, 50 per cent of all melanomas were thinner than 1.01 mm. This can be interpreted as a successful outcome of efforts in preventive medicine.

Adult↗
PubMed1990

Glucocorticoid-regulated gene expression in the immune system. Analysis of glucocorticoid-regulated transcripts from the mouse macrophage-like cell line P388D1.

To further elucidate the molecular mechanisms underlying glucocorticoid-mediated immune suppression, we have exploited cDNA cloning and subtractive screening methods to identify glucocorticoid-regulated transcripts in the mouse macrophage-like cell line, P388D1. Two of the three isolated glucocorticoid-regulated mRNA species corresponded to genes potentially important to immunoregulation: one glucocorticoid-suppressed mRNA species probably encoded the previously uncloned 3-hydroxy-3-methylglutaryl coenzyme A reductase, an enzyme that appears important for in vitro immune responses. The other mRNA species showed glucocorticoid-increased mRNA steady-state levels and was transcribed from an endogenous ecotropic type C retroviral locus. This transcript gives rise to a protein (transmembrane retroviral protein, formerly p15E), which, along with its feline and human homologs, has been implicated in immunosuppression caused by mouse, cat, and human retroviruses. Our results raise the possibility that the immunosuppressive activity of glucocorticoids might be mediated, in part, by regulating the expression of the above immunoregulatory proteins.

Animals↗
PubMed1990

Organization of the murine immunoglobulin VH complex: placement of two new VH families (VH10 and VH11) and analysis of VH family clustering and interdigitation.

During B cell development, there is an ordered expression of heavy chain variable region (VH) genes during ontogeny such that JH proximal VH genes are rearranged and expressed before the more JH distal VH genes. Thus, the relative chromosomal position of VH genes is biologically significant. We have previously employed deletion mapping to order the nine described murine VH gene families as follows: 3609-J558-(J606/VGAM3-8/S107)-3660-(X24/Q52/7183 ). (Families within parentheses were not mapped relative to each other.) In this report we continue this analysis by mapping two recently described heavy chain variable region gene families (VH10 and VH11). VH10 is located at the JH proximal end of the major cluster of J558 VH gene segments. VH11 (a very small family) is intermingled with the 3660 family. Although in general VH genes are thought to be clustered, we and others have reported some interspersion between families. To further address this issue, we have analyzed 80 recombinant phage clones containing J558 VH gene segments for the presence of other VH family genes. Our data indicate that the J558 and 3609 VH families are extensively intermingled as has recently been described for the most JH proximal Q52 and 7183 families.

Animals↗
PubMed1989

Genetic diversity of murine rheumatoid factors.

Anti-Ig autoantibodies (rheumatoid factors, RF) have been implicated in the pathogenesis of human and murine rheumatoid arthritis as well as in the regulation of normal immune responses. Their genetic origin, clonal diversity, and inducing agents, and the relatedness between RF associated with disease and those occurring under physiologic conditions are not well understood. In this study, the genetic and clonotypic origin of 34 monoclonal IgM RF-secreting hybridomas from arthritic MRL-lpr/lpr and nonarthritic MRL-+/+ and C57BL/6-lpr/lpr mice was examined by RNA hybridization. For this purpose, we used probes for 10 VH and 13 Vk gene families as well as all JH and Jk gene segments. The majority of hybridomas expressed distinct Ig gene segment patterns and, hence, were clonally unrelated. Overall, a variety of different V and J gene segments were expressed in the hybridoma panel, suggesting that a large number of distinct genetic elements participates in expression of RF-like activity. RF from arthritic mice expressed Vk messages from the overlapping Vk22 and Vk28 gene families more frequently than did those from nonarthritic mice. RF from autoimmune MRL mice, both arthritic MRL-lpr/lpr and nonarthritic MRL-+/+, showed skewed JH4 segment usage, whereas those from C57BL/6-lpr/lpr preferentially expressed JH2.

Animals↗
PubMed1989

Complexity, polymorphism, and connectivity of mouse Vk gene families.

To define the polymorphism and extent of the mouse immunoglobulin kappa (Igk) gene complex, we have analyzed restriction-enzyme digested genomic DNA from 33 inbred strains of mice with labeled DNA probes corresponding to 16 Vk protein groups (1 of them previously undescribed) and the Jk/Ck region (V, variable; J, joining; C, constant). These probes detected between 1 and 25 distinct restriction enzyme fragments (REF) that appeared in up to eight polymorphic patterns, thus defining eight mouse Igk haplotypes. The investigated portion of the Vk repertoire was estimated to encompass between 60 and 120 discernable Vk gene-containing REFs. In contrast to mouse VH gene families, several Vk gene families defined by these probes appeared to overlap. This observation has implications for Vk gene analyses by nucleic acid hybridization and raises the possibility that the Vk gene complex is a continuum of related sequences.

Amino Acid Sequence↗
PubMed1989

Mouse Vk gene classification by nucleic acid sequence similarity.

Analyses of immunoglobulin (Ig) variable (V) region gene usage in the immune response, estimates of V gene germline complexity, and other nucleic acid hybridization-based studies depend on the extent to which such genes are related (i.e., sequence similarity) and their organization in gene families. While mouse Igh heavy chain V region (VH) gene families are relatively well-established, a corresponding systematic classification of Igk light chain V region (Vk) genes has not been reported. The present analysis, in the course of which we reviewed the known extent of the Vk germline gene repertoire and Vk gene usage in a variety of responses to foreign and self antigens, provides a classification of mouse Vk genes in gene families composed of members with greater than 80% overall nucleic acid sequence similarity. This classification differed in several aspects from that of VH genes: only some Vk gene families were as clearly separated (by greater than 25% sequence dissimilarity) as typical VH gene families; most Vk gene families were closely related and, in several instances, members from different families were very similar (greater than 80%) over large sequence portions; frequently, classification by nucleic acid sequence similarity diverged from existing classifications based on amino-terminal protein sequence similarity. Our data have implications for Vk gene analyses by nucleic acid hybridization and describe potentially important differences in sequence organization between VH and Vk genes.

Animals↗
PubMed1989

Molecular aspects of autoimmunity.

Sustained humoral and/or cellular autoimmune responses are currently thought to be the primary causes of a wide spectrum of systemic and organ-specific human and animal diseases. Although a very good picture of the immunopathological characteristics of these diseases has emerged, their etiologies remain unknown. Studies initiated to define these diseases at the molecular genetic level were the subject of a recent meeting in Ville D'Esterel, Canada. Because these diseases are diverse and enormously complex, several avenues of investigation have been pursued. The primary focus of this meeting was the tripartite system of immunoglobulin (Ig), T-cell antigen receptor (TCR) and major histocompatibility complex (MHC) genes.

Animals↗