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F Hildebrandt

Publications and source records attributed to F Hildebrandt.

71 records · Page 4Linked to original sources
PubMed1993

LODVIEW: a computer program for the graphical evaluation of lod score results in exclusion mapping of human disease genes.

For linkage analysis projects aimed at mapping hereditary disease genes in humans, hundreds of highly polymorphic microsatellite markers which can be typed by PCR (PCR markers) have become available. With this technical improvement, the availability of a technique allowing for transparency in the handling of rapidly generated lod score data is becoming important. We present a computer program LODVIEW for the graphical representation of lod score data. It is designed for the input of lod score data generated with the LINKAGE package or similar programs. LODVIEW consists of 24 preformatted files, one for each chromosome. Each file contains a table for the input of lod score data and a file for the graphical representation of the data, which will show automatically any entry that is made in the respective input table. The program provides the user with published PCR marker information pre-entered into a table and graph at the correct positions corresponding to the genetic distances between markers. The graphical display of LODVIEW allows for the rapid evaluation of lod score results calculated from PCR markers on each chromosome. The following information can be obtained from the graphical display at one glance: (i) Regions of exclusion (Z(theta) < -2) and nonexclusion, (ii) markers with positive lod scores, (iii) the distribution of positive and negative lod scores among the families examined (indication of genetic heterogeneity), (iv) multipoint lod scores, and (v) the availability of PCR markers in regions of interest. The program is continually updated for novel PCR marker information from the literature. The program will help to efficiently monitor and direct the progress of exclusion mapping projects.

Chromosome Mapping↗
PubMed1993

A gene for familial juvenile nephronophthisis (recessive medullary cystic kidney disease) maps to chromosome 2p.

Familial juvenile nephronophthisis (NPH) is a chronic autosomal recessive kidney disease responsible for 15% of end stage renal failure in children. NPH is frequently (16% of cases) associated with Leber amaurosis (termed Senior-Løken syndrome, SLS). Linkage analyses, performed in 22 multiplex NPH families (18 without and 4 with ocular abnormalities), have localized the gene to a region between D2S48 and D2S51 on chromosome 2p. This was confirmed using adjacent microsatellite markers, one of which (AFM220ze3 at the D2S160 locus) gave a lod score of 4.78 at theta = 0.05 in the 18 families with isolated NPH, whereas the same marker excluded linkage with SLS. These results demonstrate linkage of the purely renal form of NPH to chromosome 2p, and suggest that there may be genetic heterogeneity between NPH and SLS.

Base Sequence↗
PubMed1993

Mapping of a gene for familial juvenile nephronophthisis: refining the map and defining flanking markers on chromosome 2. APN Study Group.

Familial juvenile nephronophthisis (NPH) is an autosomal recessive kidney disease that leads to end-stage renal failure in adolescence and is associated with the formation of cysts at the cortico-medullary junction of the kidneys. NPH is responsible for about 15% of end-stage renal disease in children, as shown by Kleinknecht and Habib. NPH in combination with autosomal recessive retinitis pigmentosa is known as the Senior-Løken syndrome (SLS) and exhibits renal pathology that is identical to NPH. We had excluded 40% of the human genome from linkage with a disease locus for NPH or SLS when Antignac et al. first demonstrated linkage for an NPH locus on chromosome 2. We present confirmation of linkage of an NPH locus to microsatellite markers on chromosome 2 in nine families with NPH. By linkage analysis with marker AFM262xb5 at locus D2S176, a maximum lod score of 5.05 at a theta max = .03 was obtained. In a large NPH family that yielded at D2S176 a maximum lod score of 2.66 at theta max = .0, markers AFM172xc3 and AFM016yc5, representing loci D2S135 and D2S110, respectively, were identified as flanking markers, thereby defining the interval for an NPH locus to a region of approximately 15 cM. Furthermore, the cytogenetic assignment of the NPH region was specified to 2p12-(2q13 or adjacent bands) by calculation of linkage between these flanking markers and markers with known unique cytogenetic assignment. The refined map may serve as a genetic framework for additional genetic and physical mapping of the region.

Chromosome Mapping↗
PubMed1992

The nephronophthisis complex: clinical and genetic aspects.

Familial juvenile nephronophthisis (NPH) and medullary cystic disease (MCD) are hereditary forms of early-onset chronic renal failure caused by the bilateral formation of cysts at the corticomedullary junction of the kidney. Polyuria, polydipsia, anemia, and growth retardation precede end-stage renal failure. The absence of edema and hypertension frequently leads to a delay in the diagnosis and commencement of therapy. The condition is a major cause of end-stage renal disease (ESRD) in children, accounting for 10%-25% of these patients. About 300 cases of NPH or MCD have been described. Although they are almost indistinguishable clinically and pathologically, the two conditions are separated by a characteristic age of onset (11.5 years in NPH vs. 28.5 years in MCD) and by the mode of inheritance (autosomal recessive in NPH vs. autosomal dominant in MCD). An association of NPH with retinitis pigmentosa is known as the Senior-Løken syndrome (SLS). Hepatic fibrosis, skeletal defects, and central nervous system abnormalities have been described in association with NPH but are typically absent in MCD. Since the pathology of NPH and MCD is similar, the term "nephronophthisis complex" has been introduced to summarize the related diseases. At present, there are no means of identifying heterozygotes, conducting prenatal diagnosis, or screening children in affected families. The histologic changes of NPH are characteristic but not specific for the disease. Cysts of 1-15 mm in diameter, located primarily at the corticomedullary junction, are seen in 70% of the patients. Light microscopy reveals a chronic sclerosing tubulo-interstitial nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning, Molecular↗
PubMed1992

Isolation of putative voltage-gated epithelial K-channel isoforms from rabbit kidney and LLC-PK1 cells.

Epithelial voltage-gated potassium (K) channels have been well studied using electrophysiological methods, but little is known about their structures. We tested the hypothesis that some of these channels belong to the Shaker gene family, which encodes voltage-gated K channels in excitable tissues. From published sequences of Shaker proteins in Drosophila, rat, and mouse brain, we chose regions that were conserved between species. Based on these protein sequences, degenerate oligonucleotides flanking the putative voltage sensor (S4) were synthesized and used as primers for the polymerase chain reaction. Five Shaker-like cDNAs were amplified from rabbit kidney cortex and three from LLC-PK1, an epithelial cell line derived from pig kidney. Each partial-length rabbit kidney cDNA is approximately 850 base pairs (bp) long. The deduced amino acid sequences contain five putative transmembrane segments and are 79-97% identical to two Shaker isoforms expressed in rat brain (RBK1 and RBK2). Sequence similarity is greatest in the putative transmembrane segments S1-S5. Importantly, the S4 segment, the putative voltage gate is highly conserved in all 5 cDNAs. Southern analysis of rabbit genomic DNA suggests that each isoform is encoded by a different gene. The partial length LLC-PK1 cDNAs are 450-bp long, and the deduced amino acid sequences are 77-99% identical to the rabbit cDNAs. This is, to our knowledge, the first demonstration that Shaker-like genes are expressed in renal epithelial cells. These genes most likely encode voltage-gated K channels involved in renal epithelial K transport.

Animals↗
PubMed1992

Induction and intracellular localization of HSP-72 after renal ischemia.

To determine whether heat shock proteins (HSPs) might be active in cellular recovery following transient ischemia, we examined rat kidneys for 70-kDa HSP (HSP-70) mRNA expression, protein elaboration, and intracellular localization after 45 min of renal ischemia and reflow of 15 min, 2, 6, and 24 h. Inducible HSP-70 mRNA is present at 15 min of reperfusion, peaks between 2 and 6 h, and falls by 24 h. Inducible 72-kDa HSP (HSP-72) protein accumulates progressively through 24 h and is found in both soluble and microsomal fractions following ischemia. Within proximal tubules, immunofluorescent localization of HSP-72 is restricted to the apical domain at 15 min, is dispersed through the cytoplasm in a vesicular pattern at 2 and 6 h, and has migrated away from the apical domain at 24 h. A portion of the vesicular HSP-72 is associated with lysosomes; no intranuclear HSP-72 is detected. The course of mRNA induction, protein elaboration, and HSP-72 localization coincides with previously described changes in proximal tubule morphology and polarity following sublethal ischemic injury. HSP-72 may be instrumental in cellular remodeling and restitution of epithelial polarity during recovery from ischemic renal injury.

Animals↗
PubMed1991

Cloning, sequence, and tissue distribution of a rabbit renal Na+/H+ exchanger transcript.

Rabbit kidney expresses a transcript that is similar to the human growth-factor-activatable Na+/H+ exchanger. PCR and library screening were used to clone overlapping 2.5 kb, 1.4 kb, and 1.8 kb cDNAs that together contain the entire coding region (2448 bp) and 5' untranslated region (726 bp) and part of the 3' untranslated region (128 bp) of a rabbit renal Na+/H+ exchanger transcript. The nucleotide and inferred amino acid sequences are highly conserved between rabbit and human (88% nucleotide identity, 95% amino acid identity). In rabbit, the transcript is expressed in both epithelial and non-epithelial tissues, with highest expression in stomach, brain, kidney, lung and ileum, and minimal expression in liver and skeletal muscle.

Amino Acid Sequence↗
PubMed1991

cDNA cloning and immunolocalization of a Na(+)-H+ exchanger in LLC-PK1 renal epithelial cells.

LLC-PK1 cells, an established line from pig kidney, express basolateral and apical Na(+)-H+ exchangers that can be distinguished by their different sensitivities to the amiloride analogue, N-ethyl-N-isopropylamiloride. In the present study, the polymerase chain reaction (PCR) and library screening were used to clone a cDNA for one of the exchangers, based on homology with the recently isolated cDNA for a human growth factor-activatable Na(+)-H+ exchanger. There proved to be significant homology between the LLC-PK1 and human sequences, with nucleotide identities of 75, 93, and 85% in the 5'-untranslated, coding, and 3'-untranslated regions, respectively. The LLC-PK1 cDNA encodes a predicted protein of 818 amino acids with a relative molecular mass of 90,999, consisting of an amino-terminal hydrophobic region and a carboxy-terminal hydrophilic region; its deduced amino acid sequence shows 95% identity with that of the human protein. To investigate the localization of the encoded protein, antisera were generated against a synthetic oligopeptide from the hydrophobic region and a fusion protein from the carboxy-terminal hydrophilic domain. Indirect immunofluorescence and confocal microscopy revealed that the antisera labeled the basolateral but not the apical membrane of confluent LLC-PK1 cells. Labeling by the antipeptide antibody was specifically blocked by preincubation with the synthetic peptide and coincided exactly with the pattern produced by a monoclonal antibody against Na(+)-K(+)-ATPase. Thus, the LLC-PK1 cDNA encodes the basolateral Na(+)-H+ exchanger, which must differ structurally from the apical form, at least in the region of the oligopeptide and the fusion protein.

Amino Acid Sequence↗
PubMed1991

Molecular biology of renal Na(+)-H+ exchangers.

Na(+)-H+ exchangers are plasma membrane proteins that are responsible for Cl- and HCO3- reabsorption and regulation of intracellular pH in several nephron segments. Recently, a cDNA encoding a human Na(+)-H+ exchanger of unknown tissue origin was cloned, and Northern blot analysis revealed that structurally similar transcripts were expressed in rabbit kidney and porcine renal epithelial cells (LLC-PK1). To clone these renal transcripts we employed cDNA library screening and the polymerase chain reaction (PCR). We obtained 2.5 kb and 1.4 kb cDNAs corresponding to the 5' untranslated region and the membrane-associated domain of a rabbit renal Na(+)-H+ exchanger. From LLC-PK1 cells we obtained 1.5 kb and 1.3 kb cDNAs encoding the membrane-associated and cytoplasmic domains. The sequences of cDNAs from these three species were very similar and suggested a high degree of evolutionary conservation. Immunolocalization of synthetic oligopeptides derived from the deduced amino acid sequences indicated that the cloned cDNAs encoded the amiloride-sensitive form of the Na(+)-H+ exchanger present in basolateral membranes of epithelia. cDNAs were also used to study regulation of Na(+)-H+ exchanger gene expression in the kidney, and we found that metabolic acidosis stimulated both the transport rate and steady-state transcript levels of the basolateral Na(+)-H+ exchanger in LLC-PK1 cells.

Acidosis↗
PubMed1988

[Exact description of non-glomerular and glomerular erythrocyte forms in pediatric hematuria].

We examined 70 urinary sediments of 35 children with non-glomerular hematuria (NGH) and 65 urinary sediments of 17 children with glomerular hematuria (GH) by phase-contrast microscopy at 1,000 X magnification. In each urinary sediment 200 erythrocytes were classified into 18 types of "non-glomerular erythrocytes" and 15 types of "glomerular erythrocytes". According to the percentage of greatly altered erythrocytes the urinary finding was termed isomorphic, mixed or dysmorphic. In 91% of the urinary sediments of patients with NGH the erythrocyte pattern was isomorphic, and in 91% of the urinary sediments of children with GH it was dysmorphic. 9 types of non-glomerular erythrocytes and 10 types of glomerular erythrocytes constituted 94.5% of all 26,809 erythrocytes examined. Torocytes (doughnut-like cells) can be considered characteristic for GH. This study demonstrates a high specificity of this method in discriminating NGH from GH. The exact morphological description of urinary erythrocytes allows the method to be reproducible. For future use examiners can concentrate on the 19 commonest erythrocyte types.

Adolescent↗
PubMed1982

Effect of catecholamines on sterol synthesis in human mononuclear cells.

The effect of adrenaline, noradrenaline, isoproterenol and dibutyryl cyclic AMP on the rate of sterol synthesis was studied in freshly isolated human mononuclear cells. Incubation of cells in a medium containing lipid depleted serum led to a two-fold rise in the rate of sterol synthesis from [14C]acetate. Adrenaline, nor-adrenaline and isoproterenol added in a concentration of 2 X 10(-5) mol/l at zero-time resulted in an inhibition of 30% of this increase in sterol synthesis after 4 h, but had no effect when the hormones were given at 4 h. This indicates that the catecholamines require some time to exert their inhibitory action on sterol synthesis. The action of catecholamines on the incorporation of [14C]acetate into sterols could be mimicked by dibutyryl cyclic AMP. Propranolol added in increasing concentrations to the incubation medium diminished or totally prevented the inhibitory effect of adrenaline, noradrenaline and isoproterenol on sterol synthesis. The results indicate that cholesterol synthesis in extrahepatic human cells, regulated predominantly by low density lipoprotein derived from plasma, is under additional control of catecholamines which may act via cyclic AMP.

Bucladesine↗