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Biomedical subjects

F Rauch

Publications and source records attributed to F Rauch.

At least 55 records · Page 3Linked to original sources
PubMed2000

Temporal and spatial expression of bone morphogenetic protein-2, -4, and -7 during distraction osteogenesis in rabbits.

The Ilizarov method of limb lengthening makes use of the fact that osteogenesis is induced at an osteotomy site when distraction is applied. It is unknown at present how the mechanical forces created by distraction are translated into biological signals. Because bone morphogenetic proteins (BMPs) are potent inducers of osteogenesis in many experimental systems, they are obvious candidates for playing a role in this process. In this study, we investigated the temporal and spatial expression of BMP-2, -4, and -7 proteins during distraction osteogenesis using immunohistochemistry. An osteotomy was performed on the right tibiae of white New Zealand rabbits. After a delay of 7 days, distraction was started at a rate of 0.25 mm/12 h for 3 weeks, followed by a 3 week consolidation phase. Each week after osteotomy one rabbit was killed for immunohistochemical studies. Staining for BMP-2, -4, and -7 was evident before distraction was applied and was mainly localized to mesenchymal cells and osteoblastic cells in the periosteal region. After distraction was started, the typical fibrous interzone developed between the osteotomy fragments, where both intramembranous and endochondral ossification were noted. In this area, cells resembling fibroblasts and chondrocytes, but not mature osteoblasts, showed intense staining for all three BMPs. This high level of expression was maintained during the entire distraction phase and then gradually disappeared during the consolidation phase. These results are compatible with the hypothesis that BMPs play an important role in the signaling pathways that link the mechanical forces created by distraction to biological responses.

Animals↗
PubMed2000

Structural and cellular changes during bone growth in healthy children.

Normal postnatal bone growth is essential for the health of adults as well as children but has never been studied histologically in human subjects. Accordingly, we analyzed iliac bone histomorphometric data from 58 healthy white subjects, aged 1.5-23 years, 33 females and 25 males, of whom 48 had undergone double tetracycline labeling. The results were compared with similar data from 109 healthy white women, aged 20-76 years, including both young adult reference ranges and regressions on age. There was a significant increase with age in core width, with corresponding increases in both cortical width and cancellous width. In cancellous bone there were increases in bone volume and trabecular thickness, but not trabecular number, wall thickness, interstitial thickness, and inferred erosion depth. Mineral apposition rates declined on the periosteal envelope and on all subdivisions of the endosteal envelope. Because of the concomitant increase in wall thickness, active osteoblast lifespan increased substantially. Bone formation rate was almost eight times higher on the outer than on the inner periosteum, and more than four times higher on the inner than on the outer endocortical surface. On the cancellous surface, bone formation rate and activation frequency declined in accordance with a fifth order polynomial that matched previously published biochemical indices of bone turnover. The analysis suggested the following conclusions: (1) Between 2 and 20 years the ilium grows in width by periosteal apposition (3.8 mm) and endocortical resorption (3.2 mm) on the outer cortex, and net periosteal resorption (0.4 mm) and net endocortical formation (1.0 mm) on the inner cortex. (2) Cortical width increases from 0.52 mm at age 2 years to 1.14 mm by age 20 years. To attain adult values there must be further endocortical apposition of 0.25 mm by age 30 years, at a time when cancellous bone mass is declining. (3) Lateral modeling drift of the outer cortex enlarges the marrow cavity; the new trabeculae filling this space arise from unresorbed cortical bone and represent cortical cancelization; (4) Lateral modeling drift of the inner cortex encroaches on the marrow cavity; some trabeculae are incorporated into the expanding cortex by compaction. (5) The net addition of 37 microm of new bone on each side of a trabecular plate results from a <5% difference between wall thickness and erosion depth and between bone formation and bone resorption rates; these small differences on the same surface are characteristic of bone remodeling. (6) Because the amount of bone added by each cycle of remodeling is so small, the rate of bone remodeling during growth must be high to accomplish the necessary trabecular hypertrophy.

Adolescent↗
PubMed2000

Normative data for iliac bone histomorphometry in growing children.

Many insights into normal and pathologic bone development can only be gained by bone histomorphometry. However, the use of this technique in pediatrics has so far been hampered by the lack of reference data. Therefore, we obtained transfixing iliac bone samples from 58 individuals between 1.5 and 22.9 years of age (25 male; tetracycline labeling performed in 48 subjects), who underwent surgery for reasons independent of abnormalities in bone development and metabolism. The results of histomorphometric analyses of cancellous parameters and cortical width are presented as means and standard deviations, as well as medians and ranges in five age groups. In addition, the original data are available from the authors. There were significant age-dependent increases in both cortical width and cancellous bone volume, the latter being due to an increase in trabecular thickness. Osteoid thickness did not vary significantly with age. Bone surface-based indicators of bone formation showed an age-dependent decline, reflecting similar changes in activation frequency. Mineral apposition rate decreased continuously with age. Parameters of bone resorption did not vary significantly between age groups. Paired biopsies from adjacent sites, obtained in eight subjects, were used to examine the reproducibility of histomorphometric parameters in children. The lowest coefficients of variation (<10%) were found for structural measures, as well as mineral apposition rate and wall thickness. The highest variability was found for cellular parameters. The availability of reference material will greatly facilitate the use of histomorphometry in pediatrics.

Adolescent↗
PubMed2000

Pamidronate treatment of severe osteogenesis imperfecta in children under 3 years of age.

Severe osteogenesis imperfecta (OI) is a hereditary disorder characterized by increased bone fragility and progressive bone deformity. Cyclical pamidronate infusions improve clinical outcome in children older than 3 yr of age with severe OI. Because earlier treatment may have potential to prevent deformities and improve functional prognosis in young children, we studied nine severely affected OI patients under 2 yr of age (2.3-20.7 months at entry) for a period of 12 months. Pamidronate was administered i.v. in cycles of 3 consecutive days. Patients received four to eight cycles during the treatment period, with cumulative doses averaging 12.4 mg/kg. Clinical changes were evaluated regularly during treatment, and radiological changes were assessed after 6-12 months of treatment. The control group consisted of six age-matched, severely affected OI patients, who had not received pamidronate treatment. During treatment bone mineral density (BMD) increased between 86-227%. The deviation from normal, as indicated by the z-score, diminished from -6.5 +/- 2.1 to -3.0 +/- 2.1 (P < 0.001). In the control group the BMD z-score worsened significantly. Vertebral coronal area increased in all treated patients (11.4 +/- 3.4 to 14.9 +/- 1.8 cm2; P < 0.001), but decreased in the untreated group (P < 0.05). In the treated patients, fracture rate was lower than in control patients (2.6 +/- 2.5 vs. 6.3 +/- 1.6 fractures/year; P < 0.01). No adverse side-effects were noted, apart from the well known acute phase reaction during the first infusion cycle. Pamidronate treatment in severely affected OI patients under 3 yr of age is safe, increases BMD, and decreases fracture rate.

Bone Density↗
PubMed2000

Deficient bone formation in idiopathic juvenile osteoporosis: a histomorphometric study of cancellous iliac bone.

Idiopathic juvenile osteoporosis (IJO), a rare cause of osteoporosis in children, is characterized by the occurrence of vertebral and metaphyseal fractures. Little is known about the histopathogenesis of IJO. We analyzed by quantitative histomorphometry iliac crest biopsies from 9 IJO patients (age, 10.0-12.3 years; 7 girls) after tetracycline labeling. Results were compared with identically processed samples from 12 age-matched children without metabolic bone disease and 11 patients with osteogenesis imperfecta type I. Compared with healthy controls, cancellous bone volume (BV) was markedly decreased in IJO patients (mean [SD]: 10.0% [3.1%] vs. 24.4% [3.8%]), because of a 34% reduction in trabecular thickness (Tb.Th) and a 37% lower trabecular number (Tb.N; p < 0.0001 each; unpaired t-test). Bone formation rate (BFR) per bone surface was decreased to 38% of the level in controls (p = 0.0006). This was partly caused by decreased recruitment of remodeling units, as shown by a trend toward lower activation frequency (54% of the control value; p = 0.08). Importantly, osteoblast team performance also was impaired, as evidenced by a decreased wall thickness (W.Th; 70% of the control value; p < 0.0001). Reconstruction of the formative sites revealed that osteoblast team performance was abnormally low even before mineralization started at a given site. No evidence was found for increased bone resorption. Compared with children with osteogenesis imperfecta (OI), IJO patients had a similarly decreased cancellous BV but a much lower bone turnover. These results suggest a pathogenetic model for IJO, in which impaired osteoblast team performance decreases the ability of cancellous bone to adapt to the increasing mechanical needs during growth. This will finally result in load failure at sites where cancellous bone is essential for stability.

Age of Onset↗
PubMed2000

Type V osteogenesis imperfecta: a new form of brittle bone disease.

Osteogenesis imperfecta (OI) is commonly subdivided into four clinical types. Among these, OI type IV clearly represents a heterogeneous group of disorders. Here we describe 7 OI patients (3 girls), who would typically be classified as having OI type IV but who can be distinguished from other type IV patients. We propose to call this disease entity OI type V. These children had a history of moderate to severe increased fragility of long bones and vertebral bodies. Four patients had experienced at least one episode of hyperplastic callus formation. The family history was positive for OI in 3 patients, with an autosomal dominant pattern of inheritance. All type V patients had limitations in the range of pronation/supination in one or both forearms, associated with a radiologically apparent calcification of the interosseous membrane. Three patients had anterior dislocation of the radial head. A radiodense metaphyseal band immediately adjacent to the growth plate was a constant feature in growing patients. Lumbar spine bone mineral density was low and similar to age-matched patients with OI type IV. None of the type V patients presented blue sclerae or dentinogenesis imperfecta, but ligamentous laxity was similar to that in patients with OI type IV. Levels of biochemical markers of bone metabolism generally were within the reference range, but serum alkaline phosphatase and urinary collagen type I N-telopeptide excretion increased markedly during periods of active hyperplastic callus formation. Qualitative histology of iliac biopsy specimens showed that lamellae were arranged in an irregular fashion or had a meshlike appearance. Quantitative histomorphometry revealed decreased amounts of cortical and cancellous bone, like in OI type IV. However, in contrast to OI type IV, parameters that reflect remodeling activation on cancellous bone were mostly normal in OI type V, while parameters reflecting bone formation processes in individual remodeling sites were clearly decreased. Mutation screening of the coding regions and exon/intron boundaries of both collagen type I genes did not reveal any mutations affecting glycine codons or splice sites. In conclusion, OI type V is a new form of autosomal dominant OI, which does not appear to be associated with collagen type I mutations. The genetic defect underlying this disease remains to be elucidated.

Adolescent↗
PubMed2000

What is new in musculo-skeletal interactions.

In this new column of the JMNI, we will give a six-monthly overview about new publications which, to our eyes, are interesting and relevant. Keeping in line with the 'spirit' of ISMNI, we take the freedom to discuss with a more holistic approach and most importantly, we encourage feed-back from the readers.

Journal Article↗
PubMed1999

Age at menarche and cortical bone geometry in premenopausal women.

Previous studies have suggested that the timing of puberty might have an impact on the adult skeleton. What composite of bone structure could be affected by the timing of puberty is unknown at present. In this study, we evaluated the relationship between age at menarche and bone cortex geometry at the distal radius. Using peripheral quantitative computed tomography, we determined total area of the radial cross section, cortical bone area, periosteal cortical perimeter, endosteal cortical perimeter, and cortical width in 169 healthy premenopausal women aged 40-45 years. When stratified according to age at menarche (early, <12 years In = 22]; intermediate, 12-14 years [n = 118]; late, >14 years [n = 29]), only endosteal cortical perimeter varied significantly between the groups (p = 0.02, by analysis of variance), the mean value being 10% higher in the late compared to the early menarche group. However, weight and body mass index also exhibited significant variations between groups. After adjustment for weight the differences in endosteal cortical perimeter remained significant (p = 0.03). In multiple regression analysis, endosteal cortical perimeter was the only parameter of cortex geometry, which was independently associated with age at menarche. In a model including height and weight, age at menarche explained about 2% of the variability in endosteal cortical perimeter (p = 0.04). These data suggest that the bone marrow cavity of the distal radius may be slightly larger when puberty occurs later. Whether this marginal effect influences fracture risk in later life appears questionable.

Adolescent↗
PubMed1998

Oestradiol regulated programmed cell death in rat vagina: terminal differentiation or apoptosis?

Rat vaginal epithelial cells (VEC) undergo division and differentiation under the influence of oestradiol in a programmed manner. The differentiation process of VEC leads to keratinization, cornification and subsequent desquamation of the dead cells. This process of programmed cell death, referred to as terminal differentiation may share some common pathways with cell death by apoptosis but differ substantially in many aspects. Terminal differentiation of VEC is accompanied by the loss of majority of the organelles including the nucleus. To understand the mechanisms that underlie this process we have analysed the regulation of DNase I (a key effector of apoptotic cell death) in rat VEC under the influence of oestradiol. The present study demonstrates that under physiological conditions, cell death in the VEC is mainly through terminal differentiation although a few cells may undergo apoptotic death involving DNA fragmentation. Unaltered levels of bcl-2 message upon oestradiol administration suggest an important role played by this molecule in preventing death of the VEC by apoptosis.

Animals↗
PubMed1998

Does leptin have an effect on bone in adult women?

Recent studies have implicated leptin in the modulation of bone mass during skeletal development. Whether leptin also exerts an influence on bone after growth has stopped is unknown at present. In this cross-sectional study on 94 women (60 premenopausal, 34 postmenopausal) aged 40-60 years, we analyzed the relationship between serum leptin and bone density and bone cortex geometry and bone metabolism. Total and trabecular bone density as well as total and cortical bone area were determined by quantitative computed tomography (QCT) at the distal radius. Bone metabolism was assessed by measuring bone-specific alkaline phosphatase, osteocalcin, procollagen type I C-terminal propeptide (PICP) and collagen type I C-terminal telopeptide in serum, and deoxypyridinoline in urine samples. None of the indices of bone density or geometry was significantly related to leptin serum concentrations (P > 0.05) before or after adjustment for body mass index (BMI). PICP was associated with serum leptin in the postmenopausal group only (r = -0.40 after adjustment for BMI; P = 0.009). Yet, as none of the other markers of bone metabolism exhibited a significant correlation with serum leptin in any of the menopausal groups, this association is likely to be due to the influence of extraskeletal factors on PICP serum levels. Thus, it appears that leptin has less influence on the mature than on the growing skeleton.

Adult↗
PubMed1998

Serum leptin is suppressed by growth hormone therapy in growth hormone-deficient children.

Leptin is a hormone which is exclusively synthesized and secreted by adipocytes. As of yet, little is known about the complex interplay of hormones in the modulation of circulating leptin levels. To investigate the effect of growth hormone (GH) therapy on leptin, leptin serum concentrations were measured by a specific radioimmunoassay in 29 children with GH deficiency (21 boys, 8 girls; age range 3-14 years) before and after 1, 3 and 6 months of treatment with recombinant human GH. At baseline, serum leptin levels were identical to those of healthy children. Serum leptin correlated with body mass index (BMI; r=0.60, p < 0.001) and weight (r=0.48, p=0.004), but not with height, age, insulinlike growth factor 1, or insulinlike growth factor-binding protein 3, and there was no sex difference (p > 0.05). After 1 month of treatment, the leptin levels had decreased to 73+/-(SEM) 13% of individual pretreatment levels (p=0.002) and remained constant thereafter. While the correlation between leptin, BMI, and weight persisted throughout the study period, the changes in leptin concentrations during treatment were not associated with changes in BMI, weight, height, insulinlike growth factor 1, and insulinlike growth factor binding protein 3. In conclusion, this preliminary study demonstrates that serum leptin decreases during GH treatment in children with GH deficiency.

Adolescent↗
PubMed1997

Androgen ablation leads to an upregulation and intranuclear accumulation of deoxyribonuclease I in rat prostate epithelial cells paralleling their apoptotic elimination.

After androgen ablation by castration, the epithelial cells of the rat ventral prostate are eliminated by apoptosis. The number of cells showing apoptotic chromatin degradation increases with time up to day 3 after castration as verified by in situ end labeling of fragmented DNA. Apoptotic chromatin degradation is catalyzed by a Ca2+, Mg2+-dependent endonuclease. Recently, evidence has been presented that suggests deoxyribonuclease I (DNase I) is identical or very closely related to the apoptotic endonuclease (Peitsch, M.C., B. Polzar, H. Stephan, T. Crompton, H.R. MacDonald, H.G. Mannherz, and J. Tschopp. 1993. EMBO [Eur. Mol. Biol. Organ.] J. 12:371-377). Therefore, the expression of DNase I in the ventral prostate of the rat was analyzed before and after androgen ablation at the level of protein, enzymatic activity, and gene transcripts using immunohistochemical and biochemical techniques. DNase I immunoreactivity was detected only in a few single epithelial cells before androgen ablation. After castration, a time-dependent increase in DNase I immunoreactivity was observed within the epithelial cells. It first appeared after about 12 h in the apical region of a large number of epithelial cells. Up to day 3 after castration, the intracellular DNase I antigenicity continuously increased, and the cell nuclei gradually became DNase I positive. At day 5, almost all nuclei of the epithelium were stained by anti-DNase I. DNase I immunoreactivity was particularly concentrated in cells showing morphological signs of apoptosis, like nuclear fragmentation, and in many cases was found to persist in apoptotic bodies. DNase I gene transcripts were detected in control animals using dot and Northern blotting as well as RNase protection assay. After androgen ablation, the amount of DNase I gene transcripts in total extractable RNA was found unchanged or only slightly decreased up to day 5. Their exclusive localization within the epithelial cells was verified by in situ hybridization. Before castration, the DNase I gene transcripts were homogeneously distributed in all epithelial cells. At day 3, DNase I-specific mRNA was found to be highly concentrated in cells of apoptotic morphology. Using the zymogram technique, a single endonucleolytic activity of about 32 kD was detected in tissue homogenates before castration. After androgen ablation, the endonucleolytic activity increased about four- to sevenfold up to day 3. At day 5, however, it had dropped to its original level. At day 1, three new endonucleolytic variants of higher molecular mass were expressed. At day 3, the predominant endonucleolytic activity exhibited an apparent molecular mass of 32 kD. Enzymatic analysis of the endonucleases present in prostate homogenates before and after castration demonstrated properties identical to DNase I. They were inhibited by chelators of divalent cations, Zn2+ ions and monomeric actin. Immunodepletion was achieved by immobilized antibodies specific for rat parotid DNase I. A polyclonal antibody raised against denatured DNase I was shown by Western blotting to stain a 32-kD band after enrichment of the endonuclease from day 0 and 3 homogenates by preparative gel electrophoresis. The data thus indicate that androgen ablation leads to translational upregulation of an endonucleolytic activity with properties identical to DNase I in rat ventral prostate, followed by its intracellular retention and final nuclear translocation in those epithelial cells that are destined to apoptotic elimination.

Androgens↗
PubMed1997

Vitamin D receptor genotypes and changes of bone density in physically active German women with high calcium intake.

Polymorphisms at the vitamin D receptor (VDR) gene have been reported to mediate important differences in bone mineral density (BMD) and bone metabolism. In this longitudinal study we examined the relationships between VDR genotypes and bone metabolism, changes in BMD and changes in ultrasound transmission velocity in a population of healthy unrelated German women. The study population comprised 50 physically active women (aged 43.3 to 62.8 years, 14 premenopausal, 36 postmenopausal) with a daily calcium intake of (mean +/- SD) 1045 +/- 338 mg, who had earlier participated in a longitudinal study on the association of physical activity and bone density and bone turnover. Each participant was genotyped for the BsmI polymorphism at the VDR gene locus. Markers of bone turnover (alkaline phosphatase, osteocalcin, procollagen type I C-terminal propeptide, collagen type I C-terminal telopeptide, tartrate-resistant acid phosphatase) were measured at baseline. BMD (determined by peripheral quantitative computed tomography at the distal radius) and ultrasound transmission velocity through bone (at calcaneus, patella and thumb) were analysed at baseline and 15 months later. The genotypic groups did not differ significantly (p > 0.05) in any of the parameters determined at baseline. Neither were there any differences between these groups in the changes of BMD or ultrasound transmission velocity during the study period. Thus, we conclude that in physically active German women with a relatively high calcium intake the impact of VDR genotypic polymorphisms on bone density, bone metabolism and changes in bone density may be of limited importance.

Alleles↗
PubMed1997

Comparison of total alkaline phosphatase and three assays for bone-specific alkaline phosphatase in childhood and adolescence.

We compared serum levels of total alkaline phosphatase (TAP) and bone-specific alkaline phosphatase (BAP) as determined by three different assays (lectin affinity electrophoresis, immunoradiometric assay, enzyme-linked immunosorbent assay) in subjects aged 5-20 years suffering from X-linked hypophosphatemic rickets (n = 14), chronic renal failure (n = 10) and chronic cholestatic liver disease (n = 16). Results were compared to controls of the same age and were expressed as standard deviation scores (SDS). TAP correlated significantly with BAP (r > 0.9 for each assay; p < 0.001) in controls. In children with cholestatic diseases, TAP (median SDS + 2.0) was elevated, but BAP, as measured by the electrophoretic assay, was within the reference range for most patients (median SDS: -0.4; p = 0.003 for the difference between the median SDS of TAP and BAP). In contrast, results for BAP as determined by the two immunoassays were not significantly different from TAP in any of the three patient groups (p > 0.05 in each group for both assays). In this study, the two immunoassays did not have a detectable advantage over lectin affinity electrophoresis in the determination of BAP.

Adolescent↗
PubMed1997

Markers of bone and collagen metabolism-problems and perspectives in paediatrics.

This paper gives a short overview of the physiology of biochemical indices of bone metabolism, their origins, the problems of interpretation of their activities and the most important clinical applications in childhood and adolescence. Markers of bone formation are all osteoblast products that enter the circulation; alkaline phosphatase (bone isoform), osteocalcin and type I procollagen peptides. Most of the traditional and new markers for bone resorption analyse the matrix (collagen) degradation products in urine from osteoclast activity. These include urinary hydroxyproline, hydroxylysine glycosides, total or free pyridinoline cross-links and cross-linked N- or C-telopeptides. Many studies have shown that both the old and new markers of bone metabolism are useful tools for basic bone biology research, for defining physiological phenomena in clinical studies, or drug trials of growth modifying therapies (e.g. growth hormone), and for following up individual patients. For the exact interpretation of bone markers it is necessary to define the factors which may influence measurement of the markers, such as age, sex, puberty, height velocity, circadian rhythms, diet, liver function and kidney clearance rates.

Biomarkers↗
PubMed1996

Distribution of deoxyribonuclease I (DNase I) and p53 in rat testis and their correlation with apoptosis.

The testis is a tissue of high proliferative activity. In this organ, sperm cells (spermatozoa) are produced from stem cells (spermatogonia) by two consecutive steps of cell multiplication and spermatid cytodifferentiation. Mitotic proliferation of spermatogonia generates primary spermatocytes which enter meiosis, leading to the generation of spermatids. The number of cells entering meiosis is held constant, since outnumbering spermatogonia or premeiotic spermatocytes are eliminated by apoptosis (programmed cell death). During apoptosis, the nuclear chromatin is internucleosomally degraded by the activity of a Ca2+, Mg2+-dependent endonuclease. Recent data indicate that deoxyribonuclease I (DNase I) is identical to the apoptotic endonuclease responsible for the internucleosomal DNA degradation. Previous results using primers specific for rat parotid DNase I in a polymerase chain reaction have demonstrated the presence of DNase I-specific gene transcripts in rat testis. We have therefore analysed the presence of DNase I in rat testis by immunohistochemistry and biochemical procedures. The presence of DNase I-like endonucleolytic activity was verified enzymatically. DNase I immunoreactivity was detected in the nuclei of a few spermatogonia and premeiotic spermatocytes, but within the acrosomic vesicle of all spermatids and spermatozoa. In situ hybridisation revealed the accumulation of DNase I-specific gene transcripts in a small number of spermatogonia and/or premeiotic spermatocytes, but in a large number of spermatids. The occurrence of apoptotic DNA fragmentation was investigated by in situ end-labelling (ISEL) of free 3'-OH DNA ends and gave positive nuclear staining of only very few spermatogonia. No positive ISEL staining was observed in maturing spermatids and/or spermatozoa. These data support the notion that, within the seminiferous epithelium, the number of primary spermatocytes entering meiosis is controlled by apoptosis. In addition, they demonstrated that mature sperm cells are equipped with an endonuclease that might be used for DNA degradation during their elimination at later stages of their life span. The expression and distribution of the tumour suppressor gene product, p53, was analysed by immunostaining. Strong p53 immunoreactivity was observed in the nuclei of a number of spermatogonia, of some premeiotic spermatocytes and probably in all spermatids. Thus, p53 expression appeared to parallel that of DNase I. In contrast, p53 immunoreactivity was absent in mature spermatozoa present in the lumen of the testicular tubules or the ductus epididymidis. It is therefore proposed that at later stages of spermatid maturation most probably before their release as mature spermatozoa-the p53 gene product was either degraded or retained in residual bodies, since p53 immunoreactivity was found to be concentrated within these organelles.

Animals↗
PubMed1996

A novel mutation in the coding region for neurophysin-II is associated with autosomal dominant neurohypophyseal diabetes insipidus.

OBJECTIVE: Autosomal dominant neurohypophyseal diabetes insipidus (ADNDI) is a rare cause of diabetes insipidus, in which AVP serum levels are insufficient. AVP is synthesized along with neurophysin-II (NPII) as an AVP-NPII precursor polypeptide in the hypothalamus. After proteolytic cleavage during axonal transport, AVP and NPII are reassembled and stored loosely bound to each other in the posterior pituitary until both are released into the circulation. In this study, we investigated the genetic basis of ADNDI in a German kindred with 10 affected members spanning three generations. DESIGN: Genomic DNA was isolated from peripheral blood leucocytes. The entire coding region of the AVP-NPII gene of one of the affected persons was amplified by polymerase chain reaction (PCR) and subjected to nucleotide sequence analysis. Sequencing results were confirmed by restriction enzyme analysis of PCR products. PATIENTS: Six affected and two unaffected members of a family with ADNDI and 54 unrelated healthy control subjects were studied. RESULTS: The index patient was found by direct sequencing to be heterozygous for a G to T transversion at nucleotide position 1884 (exon 2) of the AVP-NPII gene. This mutation introduced a new recognition site for the restriction enzyme Ava II, which was used to test for the presence of the mutation in other family members and in control subjects. The mutation was detected in all family members with ADNDI, but was not found in unaffected family members or in control subjects. The mutation encodes a valine in place of the normal glycine at amino acid 65 of NPII, which is known to be highly conserved during evolution. CONCLUSIONS: In this family, the autosomal dominant neurohypophyseal diabetes insipidus phenotype cosegregates with a point mutation in a region of the AVP-neurophysin-II gene which codes for the carboxy-terminal domain of neurophysin-II. Although the altered amino acid is not directly involved in AVP binding, the mutation might lead to conformational changes that impair the dimerization of neurophysin-II molecules. This could in turn affect the AVP binding affinity of neurophysin-II or might interfere with the transport of the AVP-neurophysin-II precursor in the AVP-producing cells of the hypothalamus.

Base Sequence↗