Missense variant c.1460 T > C (p.L487P) enhances protein degradation of ER mannosyltransferase ALG9 in two new ALG9-CDG patients presenting with West syndrome and review of the literature

ALG9-CDG is a CDG-I defect within the group of Congenital Disorders of Glycosylation (CDG). We here describe the clinical symptoms of two new and unrelated ALG9-CDG patients, both carrying the novel homozygous missense variant c.1460 T > C (p.L487P) in the ALG9 gene which led to global developmental delay, psychomotor disability, facial dysmorphisms, brain and heart defects, hearing loss, hypotonia, as well as feeding problems. New clinical symptoms comprised West syndrome with hypsarrhythmia. Quantitative RT-PCR analysis revealed a significantly enhanced ALG9 mRNA transcript level, whereas the protein amount in fibroblasts was significantly reduced. This could be ascribed to a stronger degradation of the mutated ALG9 protein in patient fibroblasts. Lipid-linked oligosaccharide analysis showed an ALG9-CDG characteristic accumulation of Man₆GlcNAc₂-PP-dolichol and Man₈GlcNAc₂-PP-dolichol in patient cells. The clinical findings of our patients and of all previously published ALG9-CDG patients are brought together to further expand the knowledge about this rare N-glycosylation disorder. SYNOPSIS: Homozygosity for p.L487P in ALG9 causes protein degradation and leads to West syndrome.

Haploinsufficiency of NR4A2 is associated with a neurodevelopmental phenotype with prominent language impairment

Non-recurrent deletions in 2q24.1, minimally overlapping two genes, NR4A2 and GPD2, were recently described in individuals with language impairment and behavioral and cognitive symptoms. We herewith report on a female patient with a similar phenotype of severe language and mild cognitive impairment, in whom we identified a de novo deletion covering only NR4A2. NR4A2 encodes a transcription factor highly expressed in brain regions critical for speech and language and implicated in dopaminergic neuronal development. Our findings of a de novo deletion of NR4A2 in an individual with mild intellectual disability and prominent speech and language impairment provides further evidence for NR4A2 haploinsufficiency being causative for neurodevelopmental and particularly language phenotypes.

Co-Occurence of Reciprocal Translocation and COL2A1 Mutation in a Fetus with Severe Skeletal Dysplasia: Implications for Genetic Counseling

Achondrogenesis type II is an autosomal-dominant disease leading to severe micromelic dwarfism. Here, we report on the postmortem identification of a de novo heterozygous mutation in the COL2A1 gene (c.1529G>A, p.Gly510Asp) in a fetus who presented with generalized hydrops fetalis and severe micromelia during prenatal sonographic examinations. Initially, a reciprocal translocation t(4;17)(q31;p13) was detected in this fetus by chorionic villus sampling. Subsequent chromosomal analysis of maternal and paternal blood showed that the patient's mother was carrier of the same reciprocal translocation. SNP array analysis of the fetus did not provide evidence for chromosomal imbalances or CNVs that could be associated with the fetal phenotype. The coexistence of a cytogenetic (reciprocal translocation) and a molecular genetic (COL2A1 mutation) abnormality in the fetus carries important implications for genetic counseling.

Cancer spectrum and frequency among children with Noonan, Costello, and cardio-facio-cutaneous syndromes

Background:

Somatic mutations affecting components of the Ras-MAPK pathway are a common feature of cancer, whereas germline Ras pathway mutations cause developmental disorders including Noonan, Costello, and cardio-facio-cutaneous syndromes. These ‘RASopathies' also represent cancer-prone syndromes, but the quantitative cancer risks remain unknown.

Methods:

We investigated the occurrence of childhood cancer including benign and malignant tumours of the central nervous system in a group of 735 individuals with germline mutations in Ras signalling pathway genes by matching their information with the German Childhood Cancer Registry.

Results:

We observed 12 cases of cancer in the entire RASopathy cohort vs 1.12 expected (based on German population-based incidence rates). This corresponds to a 10.5-fold increased risk of all childhood cancers combined (standardised incidence ratio (SIR)=10.5, 95% confidence interval=5.4–18.3). The specific cancers included juvenile myelomonocytic leukaemia=4; brain tumour=3; acute lymphoblastic leukaemia=2; rhabdomyosarcoma=2; and neuroblastoma=1. The childhood cancer SIR in Noonan syndrome patients was 8.1, whereas that for Costello syndrome patients was 42.4.

Conclusions:

These data comprise the first quantitative evidence documenting that the germline mutations in Ras signalling pathway genes are associated with increased risks of both childhood leukaemia and solid tumours.

A Novel SLC6A8 Mutation in a Large Family with X-Linked Intellectual Disability: Clinical and Proton Magnetic Resonance Spectroscopy Data of Both Hemizygous Males and Heterozygous Females

X-linked creatine transport (CRTR) deficiency, caused by mutations in the SLC6A8 gene, leads to intellectual disability, speech delay, epilepsy, and autistic behavior in hemizygous males. Additional diagnostic features are depleted brain creatine levels and increased creatine/creatinine ratio (cr/crn) in urine. In heterozygous females the phenotype is highly variable and diagnostic hallmarks might be inconclusive. This survey aims to explore the intrafamilial variability of clinical and brain proton Magnetic Resonance Spectroscopy (MRS) findings in males and females with CRTR deficiency. X-chromosome exome sequencing identified a novel missense mutation in the SLC6A8 gene (p.G351R) in a large family with X-linked intellectual disability. Detailed clinical investigations including neuropsychological assessment, measurement of in vivo brain creatine concentrations using quantitative MRS, and analyses of creatine metabolites in urine were performed in five clinically affected family members including three heterozygous females and one hemizygous male confirming the diagnosis of CRTR deficiency. The severe phenotype of the hemizygous male was accompanied by most distinct aberrations of brain creatine concentrations (-83% in gray and -79% in white matter of age-matched normal controls) and urinary creatine/creatinine ratio. In contrast, the heterozygous females showed varying albeit generally milder phenotypes with less severe brain creatine (-50% to -33% in gray and -45% to none in white matter) and biochemical urine abnormalities. An intrafamilial correlation between female phenotype, brain creatine depletion, and urinary creatine abnormalities was observed. The combination of powerful new technologies like exome-next-generation sequencing with thorough systematic evaluation of patients will further expand the clinical spectrum of neurometabolic diseases.

Phenotypic spectrum associated with CASK loss-of-function mutations

BACKGROUND

Heterozygous mutations in the CASK gene in Xp11.4 have been shown to be associated with a distinct brain malformation phenotype in females, including disproportionate pontine and cerebellar hypoplasia.

METHODS

The study characterised the CASK alteration in 20 new female patients by molecular karyotyping, fluorescence in situ hybridisation, sequencing, reverse transcriptase (RT) and/or quantitative real-time PCR. Clinical and brain imaging data of a total of 25 patients were reviewed.

RESULTS

11 submicroscopic copy number alterations, including nine deletions of ~11 kb to 4.5 Mb and two duplications, all covering (part of) CASK, four splice, four nonsense, and one 1 bp deletion are reported. These heterozygous CASK mutations most likely lead to a null allele. Brain imaging consistently showed diffuse brainstem and cerebellar hypoplasia with a dilated fourth ventricle, but of remarkably varying degrees. Analysis of 20 patients in this study, and five previously reported patients, revealed a core clinical phenotype comprising severe developmental delay/intellectual disability, severe postnatal microcephaly, often associated with growth retardation, (axial) hypotonia with or without hypertonia of extremities, optic nerve hypoplasia, and/or other eye abnormalities. A recognisable facial phenotype emerged, including prominent and broad nasal bridge and tip, small or short nose, long philtrum, small chin, and/or large ears.

CONCLUSIONS

These findings define the phenotypic spectrum associated with CASK loss-of-function mutations. The combination of developmental and brain imaging features together with mild facial dysmorphism is highly suggestive of this disorder and should prompt subsequent testing of the CASK gene.

[Anticoagulation during pregnancy following an artificial heart valve replacement]

HISTORY AND CLINICAL FINDINGS

A 23-year-old woman had received a mechanical bileaflet mitral valve prosthesis because of severe mitral valve insufficiency caused by an acute bacterial endocarditis with vegetations. One year after the operation the patient suffered on two miscarriages under oral anticoagulation by phenprocoumon. Present, she was referred to our center with the question of conversion to low molecular weight heparine because of continued yearning for a baby.

INVESTIGATIONS

At admission the woman was in good general and nutritional condition. Echocardiography showed a regular prosthetic function. Blood analysis, electrolyte parameters and enzyme values were normal, further laboratory investigations revealed a factor-V-Leiden-mutation. A chromosomal analysis detected no aberrations.

TREATMENT AND COURSE

The oral anticoagulation by phenprocoumon was switched to subcutaneous low molecular weight heparine in therapeutical dosage. Anti-factor-Xa-activity was controlled at regular intervals. Further pregnancy was uneventful for both, mother and child. A healthy infant was born by caesarean section at 40 (th) week of gestation.

CONCLUSIONS

Treatment with anticoagulation by phenprocoumon is indispensable for mechanical heart valve protheses. Conversion to low molecular weight heparine is possible in patients who insistent request to conceive. The anticoagulation by low molecular weight heparine avoids teratogenic effects during pregnancy because the placenta is impermeable to that heparin. Furthermore, prophylaxis of thromoses by low molecular weight heparine is probably in almost the same manner as by phenprocoumon.

Prm3, the fourth gene in the mouse protamine gene cluster, encodes a conserved acidic protein that affects sperm motility

The protamine gene cluster containing the Prm1, Prm2, Prm3, and Tnp2 genes is present in humans, mice, and rats. The Prm1, Prm2, and Tnp2 genes have been extensively studied, but almost nothing is known about the function and regulation of the Prm3 gene. Here we demonstrate that an intronless Prm3 gene encoding a distinctive small acidic protein is present in 13 species from seven orders of mammals. We also demonstrate that the Prm3 gene has not generated retroposons, which supports the contention that genes that are expressed in meiotic and haploid spermatogenic cells do not generate retroposons. The Prm3 mRNA is first detected in early round spermatids, while the PRM3 protein is first detected in late spermatids. Thus, translation of the Prm3 mRNA is developmentally delayed similar to the Prm1, Prm2, and Tnp2 mRNAs. In contrast to PRM1, PRM2, and TNP2, PRM3 is an acidic protein that is localized in the cytoplasm of elongated spermatids and transfected NIH-3T3 cells. To elucidate the function of PRM3, the Prm3 gene was disrupted by homologous recombination. Sperm from Prm3(-/-) males exhibited reductions in motility, but the fertility of Prm3(-/-) and Prm3(+/+) males was similar in matings of one male and one female. We have developed a competition test in which a mutant male has to compete with a rival wild-type male to fertilize a female; the implications of these results are also discussed.

Dystrophin-deficiency increases the susceptibility to doxorubicin-induced cardiotoxicity

BACKGROUND AND AIM

The clinical use of doxorubicin (DOX) and other anthracyclines is limited by a dosage-dependent cardiotoxicity, which can lead to cardiomyopathy. The role of the individual genetic makeup in this disorder is poorly understood. Alterations in genes encoding cardiac cytoskeleton or sarcolemma proteins may increase the susceptibility to doxorubicin-related cardiotoxicity.

METHODS

Female dystrophin-deficient mice (MDX) and age-matched wild-type mice underwent chronic treatment with doxorubicin. Cardiac function and tissue damage were assessed by echocardiography and histopathology, respectively. Gene expression changes were investigated using microarrays.

RESULTS

DOX treatment resulted in mortality, cardiac insufficiency, and cardiac interstitial fibrosis. These alterations were more pronounced in DOX-treated MDX mice than in DOX-treated wild-type mice. Changes in gene expression were more numerous in MDX mice, including genes involved in cell adhesion, oxidative stress, cytoskeleton organization, inflammatory and immune response and cell death.

CONCLUSIONS

Dystrophin deficiency facilitates the development and progression of doxorubicin-induced cardiac injury. The underlying mechanisms may involve changes in cell adhesion, in cytoskeleton, as well as in inflammatory and immune responses. Genetic variants of cytoskeletal proteins in humans may affect the individual susceptibility to doxorubicin. Cardiotoxic drugs may accelerate the manifestation of pre-clinical cardiomyopathies caused by deficiencies in cytoskeletal or sarcolemma proteins.

Premature translation of transition protein 2 mRNA causes sperm abnormalities and male infertility

During mammalian spermiogenesis somatic histones are replaced at first by transition proteins, which are in turn replaced by the protamines, forming the sperm nucleoprotamines. It is believed that transition protein 2 (Tnp2) is necessary for maintaining the normal processing of protamines and, consequently, the completion of chromatin condensation. The transition protein mRNAs are stored in translationally inert messenger ribonucleoprotein particles for up to 7 days until translational activation in elongated spermatids. Substantial evidence suggests an involvement of 3'untranslated region (UTR) in the translational regulation of the Tnp2 mRNAs. In order to determine the role of Tnp2 3'UTR in translational regulation and to study whether the translational repression of Tnp2 mRNA is necessary for normal spermatid differentiation in mice, we generated transgenic mice that carry a Tnp2-hGH transgene. In this transgene, 3'UTR of Tnp2 gene was replaced by 3' 3'UTR of human growth hormone gene. In these transgenic animals, transcription and translation of Tnp2 occur simultaneously in round spermatids which is an evidence for involvement of Tnp2 3'UTR in its translation repression. Premature translation of Tnp2 mRNA caused abnormal head morphogenesis, reduced sperm motility and male infertility. These results show clearly that a strict temporal and stage-specific Tnp2 translation is necessary for the correct differentiation of round spermatids into mature spermatozoa and for male fertility.

NAD(P)H oxidase and multidrug resistance protein genetic polymorphisms are associated with doxorubicin-induced cardiotoxicity

BACKGROUND

A significant number of patients treated with anthracyclines develop cardiotoxicity (anthracycline-induced cardiotoxicity [ACT]), mainly presenting as arrhythmias (acute ACT) or congestive heart failure (chronic ACT). There are no data on pharmacogenomic predictors of ACT.

METHODS AND RESULTS

We genotyped participants of the German non-Hodgkin lymphoma study (NHL-B) who were followed up for the development of heart failure for a median of >3 years. Single-nucleotide polymorphisms (SNPs) were selected from 82 genes with conceivable relevance to ACT. Of 1697 patients, 55 developed acute and 54 developed chronic ACT (cumulative incidence of either form, 3.2%). We detected 5 significant associations with polymorphisms of the NAD(P)H oxidase and doxorubicin efflux transporters. Chronic ACT was associated with a variant of the NAD(P)H oxidase subunit NCF4 (rs1883112, -212A-->G; symbols with right-pointing arrows, as edited?' odds ratio [OR], 2.5; 95% CI, 1.3 to 5.0). Acute ACT was associated with the His72Tyr polymorphism in the p22phox subunit (rs4673; OR, 2.0; 95% CI, 1.0 to 3.9) and with the variant 7508T-->A (rs13058338; OR, 2.6; 95% CI, 1.3 to 5.1) of the RAC2 subunit of the same enzyme. In agreement with these results, mice deficient in NAD(P)H oxidase activity, unlike wild-type mice, were resistant to chronic doxorubicin treatment. In addition, acute ACT was associated with the Gly671Val variant of the doxorubicin efflux transporter multidrug resistance protein 1 (MRP1) (OR, 3.6; 95% CI, 1.6 to 8.4) and with the Val1188Glu-Cys1515Tyr (rs8187694-rs8187710) haplotype of the functionally similar MRP2 (OR, 2.3; 95% CI, 1.0 to 5.4). Polymorphisms in adrenergic receptors previously demonstrated to be predictive of heart failure were not associated with ACT.

CONCLUSIONS

Genetic variants in doxorubicin transport and free radical metabolism may modulate the individual risk to develop ACT.

Prenatal DNA diagnosis of Noonan syndrome in a fetus with massive hygroma colli, pleural effusion and ascites

Prenatal molecular genetic diagnosis for Noonan syndrome I is reported. Noonan syndrome was suspected because of large cystic hygroma colli, massive pleural effusion and ascites at 23 weeks of gestation and normal karyotype (46,XX). DNA was prepared from amnion cells and screened for mutations in the PTPN11 gene. In exon 8, a missense mutation (S285F) was found. Delivery was induced at 33 weeks of gestation because of silent cardiotocography (CTG). Despite immediate drainage of the hydrothorax, mechanical ventilation was insufficient and the child died 9 h after birth due to severe pulmonary hypoplasia. Pleural punctate was enriched for small lymphocytes and thus was characterized as chylus. Prenatal ultrasound findings in Noonan syndrome usually are unspecific and rarely lead to a diagnosis. However, with the combination of cystic hygroma, pleural effusion, ascites and normal karyotype Noonan syndrome should be considered and DNA testing for PTPN11 mutations may be appropriate. Malformations of lymphatic vessels and/or chylothorax in Noonan syndrome seem to be more frequent than usually anticipated.

A novel positive tetracycline-dependent transactivator (rtTA) variant with reduced background activity and enhanced activation potential

The tetracycline-controlled transcription system has become one of the most potent systems for experimental manipulations of transcription levels in vivo. Here we report on rtTA variants, which were generated by combining the existing positively regulated Tet repressor domains of rtTA and rtTA-M2 with a modified and multimerized minimal transactivation domain from VP16 (L-domain). A transactivator with multimerized L-domains shows drastically reduced background activity and enhanced transcriptional activation on different tetracycline-responsive promoters. The new rtTA variants require higher doses of doxycycline and display a more linear dose-response curve than the original rtTA or rtTA-M2 proteins.

Oxidative stress in rat cortical neurons and astrocytes induced by paraquat in vitro

Oxidative stress has been discussed as crucial mechanism of neuronal cell death in the adult brain. However, it was not clear until now whether neurons are more sensitive to oxidative stress than the other cells in the brain, e.g. astrocytes. Therefore both cell types were exposed to oxidative stress provoked by the redox-cycling compound paraquat. Cortical neurons were found to be more sensitive towards paraquat toxicity than astrocytes as shown by MTT and Neutral Red assay, two different cytotoxicity assays. Mitochondrial functions were determined by the mitochondrial membrane potential and intracellular ATP concentrations. Again cortical neurons were more severely impaired (by paraquat than astrocytes). The production of reactive oxygen species after paraquat exposure was much higher in cortical neurons than in astrocytes and correlated with a higher depletion of GSH (intracellular glutathion). Lipid peroxidation could be shown in astrocytes via the breakdown product malondialdehyde (MDA) whereas in cortical neurons 4-hydroxynonenal (4-HNE) was detected as this endpoint. If and how oxidative stress influences the antioxidant defense was determined via changes in the expression of antioxidant enzymes. Paraquat exposure lead to a 2-3 fold increase of catalase, MnSOD and CuZnSOD mRNA expression in astrocytes. In contrast to astrocytes, in cortical neurons catalase and MnSOD mRNA levels were only marginally elevated above 1.5-fold by treatment with paraquat. Expression levels of glutathione peroxidase (GPx) mRNA were the only one that were not changed in both cell types after paraquat exposure. It is concluded that the more marked increase in expression levels of antioxidant enzymes may render astrocytes more resistant to oxidative stress than neuronal cells.

A 74-bp promoter of the Tnp2 gene confers testis- and spermatid-specific expression in transgenic mice

During the final stages of spermatogenesis, round spermatids undergo several morphological, biochemical, and physiological modifications which result in the formation of mature spermatozoa. One of these is the nuclear condensation, achieved by the replacement of somatic-type and testis-specific histones by transition proteins and protamines leading to cessation of transcription several days before the completion of spermiogenesis. Therefore, a strict temporal and stage-specific gene expression is necessary for the correct differentiation of round spermatids into mature spermatozoa. In this study, the 5' regulatory region of rat Tnp2 gene was investigated by primer extension analysis and transgenic mice study. Primer extension analysis revealed a transcription start site which lies 70 bp upstream of the translation start codon. By transgenic mice studies, we demonstrated that a 147-bp 5' untranslated region corresponding to the region -74 to +73 is sufficient to confer testis- and spermatid-specific expression of rat Tnp2 gene.

Rat transition nuclear protein 2 regulatory region directs haploid expression of reporter gene in male germ cells of transgenic mice

During spermiogenesis, the successive replacement of somatic histones by basic proteins, the transition nuclear proteins and protamines, allows normal sperm condensation. Transition nuclear protein 2 (TNP2) is transcribed postmeiotically in round spermatids. In order to determine regulatory flanking sequences responsible for stage specific expression of TNP2 gene, different transgenic mice were generated by microinjection of fertilized eggs. We demonstrate here that 525 bp of 5'- and 920 bp of 3'-flanking sequences of rat TNP2 gene could properly and efficiently direct chloramphenicol acetyltransferase gene expression to the postmeiotic male germ cells of transgenic mice. During male germ cell differentiation the first transgene transcripts were observed in round spermatids and translation started 6 days later in elongating spermatids, which is an evidence for posttranscriptional regulation of transgene expression. In contrast, transgenic mice bearing only the 525 bp 5'-flanking sequences of rat transition protein 2 gene and 3'-flanking sequences of the simian virus 40 large T antigen showed low levels of transgene expression in testis. From these results, it can be concluded that the 525 bp 5'-flanking sequences regulate the cell specific expression and the sequences located in 920 bp 3'-flanking region either enhance the transgene expression in the male germ cells or may have a posttranscriptional role in stabilizing the mRNA in addition to its function in delaying the mRNA translation. Using comparative alignment of 5'-flanking of TNP2 genes from different species, the putative regulatory sequences are identified.

Bioassay of mannitol and caprolactam and assessment of response to diethylnitrosamine in heterozygous p53 -deficient (+/-) and wild type (+/+) mice

Alternative bioassays of mannitol (MAN) and caprolactam (CAP) were conducted in transgenic p53-deficient mice. Also, to assess the sensitivity of the transgenic mice to a model DNA-reactive carcinogen, the hepatic effects of diethylnitrosamine (DEN) were compared in the wild type background strain of mouse and in the transgenic derivative. Fifty-one male wild type strain C57BL/6 mice p53 (+/+), 8 weeks old, and 51 heterozygous p53 (+/-) C57BL/6 Tac-[KO] Trp53 N5 mice, 8 weeks old, were allocated to six experimental groups as follows: groups 1 (wild type +/+) and 2 (p53 +/-) served as room controls, groups 3 (+/+) and 4 (+/-) were exposed orally (gavage) to 50 mumol/kg body weight DEN weekly for a total of ten doses during the first 10 weeks of the study, group 5 (+/-) was exposed to 15,000 ppm CAP in the diet for up to 26 weeks, and group 6 (+/-) was exposed to 50,000 ppm MAN in the diet for up to 26 weeks. After 10 weeks, liver from control and DEN-exposed mice was used for O4-ethylthymidine (O4-EtT) DNA adduct analysis by the immunoslot blot method. The cell replicating fraction (RF) in the liver was determined by quantification of the percentage of immunohistochemically stained hepatocytes positive for proliferating cell nuclear antigen. No significant or consistent body or liver weight changes were present in any of the treatment groups. No consistent and pertinent changes in RF values were present in any of the treatment groups. None of the tested substances produced neoplasms of any type in p53 (+/-) mice. DEN induced comparable levels of O4-EtT adducts in the liver in both wild type and p53 +/- genotypes, but no morphologic changes were evident in the livers of either genotype. The lack of response to DEN, in spite of formation of DNA adducts, may reflect the resistance to hepatocarcinogenesis of the background C57BL/6 strain of the transgenic, and calls into question the general sensitivity of this transgenic for detection of carcinogenic effects.

Photochemical mutagenicity of phototoxic and photochemically carcinogenic fluoroquinolones in comparison with the photostable moxifloxacin

Certain fluoroquinolone (FQ) antibiotics that show clinical phototoxicity and experimental photochemical carcinogenicity have been found to interact with ultraviolet-A (UVA) radiation to produce oxidative DNA damage in cultured cells and isolated DNA. To study the biological consequences of oxidative DNA damage in mammalian cells, the photochemical mutagenicity of two photoactive FQs, lomefloxacin and Bay y3118, was studied in V79 cells in comparison with that of the photostable moxifloxacin. Lomefloxacin and Bay y3118 were photochemically mutagenic to V79 cells with UVA irradiation, increasing the mutation frequency by about eightfold (400 microM, 6000 J/m2) and tenfold (50 microM, 1000 J/m2), respectively, whereas no photochemical mutagenicity was observed with moxifloxacin (400 microM, 9000 J/m2). We suggest that the previously reported ability of lomefloxacin and Bay y3118 to photochemically produce oxidative DNA damage, which is known to be mutagenic, may be the basis for the photochemical mutagenicity and the reported photochemical carcinogenicity. The photostable moxifloxacin appears to lack such properties.

Rat cortical neuron cultures: an in vitro model for differentiating mechanisms of chemically induced neurotoxicity

Various structurally unrelated chemicals [2,5 hexandione, acrylamide, organophosphates like mipafox, beta,beta iminodipropionnitrile (IDPN), 3-nitropropionic acid (3-NP), potassium cyanide (KCN), paraquat, and NMDA (N-methyl-D-apartic acid)] are known to cause degenerative damage of the peripheral or central nervous system. Differentiated neuronal cell cultures obtained from fetal rats have been used to differentiate the mechanisms underlying this type of neurotoxicity. Cytotoxicity as measured by a viability assay was not sensitive enough and had to be supplemented by further endpoints covering effects on cytoskeleton and on the energy state of the cells [glucose consumption, mitochondrial membrane potential and adenosine 5'-triphosphate (ATP) concentration]. Compounds like the delayed neurotoxic organophosphates, exert a selective direct effect on cytoskeleton elements in this model at concentrations distinctly below cytotoxic concentrations. Other compounds, like KCN, paraquat, and 3-NP selectively disrupt the balance between energy supply and demand of the neurons either by interacting with mitochondrial respiration or glycolysis. For these compounds cytoskeletal damage seemed to be secondary to the energy depletion. For NMDA, 2,5 hexandione and acrylamide, both mechanisms may contribute to the neuronal damage. In conclusion, primary cortical neuronal cultures of the rat are well suited to detect a neurotoxic potential and to differentiate its underlying mechanisms. Damage of the cytoskeleton may be considered as an endpoint mechanistically related to degenerative neuropathic effects.

Evidence for translational repression of the SOCS-1 major open reading frame by an upstream open reading frame

The suppressor of cytokine signalling 1 protein (SOCS-1) belongs to a novel family of cytokine inducible factors which function as inhibitors of the JAK/STAT pathway. While SOCS-1 previously has been described as a single-exon gene, here we present evidence for an additional 5' exon, separated by a 509 bp intron from exon 2. Exon 1 and part of exon 2 contain an open reading frame of 115 nt, ending one nucleotide upstream of the major reading frame. Using SOCS-1-promoter/luciferase constructs, we investigated which sequences are involved in the regulation of SOCS-1 expression. Serial promoter deletion clones indicate the localization and functionality of SP1, interferon-stimulated responsive elements (ISRE), and interferon-gamma-activated sites (GAS) promoter elements in the SOCS-1 5' flanking region. We present evidence that the upstream open reading frame (uORF) represses the translation of the downstream major open reading frame (mORF). Mutating the start codon of the uORF relieves this repression. Our data indicate that expression of the SOCS-1 protein is repressed on translational level by a mechanism, which bears similarities to that postulated for genes like retinoic acid receptor beta2 (RARbeta2), S-adenosylmethionine-decarboxylase (AdoMetDC), Bcl-2, and others.

Nonlinearity of nuclear enlargement in hepatocytes induced by the carcinogen N'-nitrosomorpholine in Ovo

In this study we investigated the effects of different doses of the carcinogenic nitrosamine N'-nitrosomorpholine (NNM) on the occurrence of enlarged nuclei in embryonic turkey liver in order to evaluate whether this parameter might represent a quantitative indicator of chemically induced hepatocarcinogenesis. Therefore fertile embryo turkey eggs were injected with NNM over a dose range of 125 microg-8 mg/egg at the first day of incubation. After incubation for 24 days, the embryonic livers were removed and processed for histologic evaluation. The induction of hepatocytes with enlarged nuclei (nuclear profiles > 35 microm2 was quantitated morphometrically in hematoxylin and eosin (H&E)-stained sections. The NNM treatment increased both the number of enlarged hepatocyte nuclei and the areas of the individual profiles of the enlarged nuclei in a dose-dependent manner. Exposure to 500 microg-8 mg NNM/egg resulted in a statistically significant increase in the number of hepatocytes with enlarged nuclei. The lower doses of 250 microg and 125 microg NNM/egg showed a similar albeit not significant trend. Signs for cytotoxic effects on the hepatocytes, such as necrosis or enhanced cytoplasmic vacuolization, were observed in tissue samples of embryos exposed to 4 or 8 mg NNM, but not after treatment with lower doses. The dose-effect curve for the induction of the nuclear enlargement was nonlinear, with a moderate slope for lower dose levels of 125-500 microg/egg and a steep slope for higher dose levels of 1-8 mg. Findings in rodents indicate a pathogenic link between the occurrence of enlarged nuclei and hepatocarcinogenesis. Based on the results with NNM, it is suggested that the in ovo model may represent a rapid, convenient, and inexpensive experimental approach for dose effect investigations on chemically induced hepatocarcinogenesis.

DNA analysis of Huntington's disease: five years of experience in Germany, Austria, and Switzerland

OBJECTIVE

To review the direct DNA testing for Huntington's disease (HD) in Germany, Switzerland, and Austria from 1993 to 1997, and to analyze the population with regard to age structure, gender, and family history.

METHODS

Twelve laboratories (nine in Germany, two in Austria, and one in Switzerland) recorded data pertaining to repeat number, gender, age at molecular diagnosis, and family history of probands. The molecular test was categorized as either diagnostic (for symptomatic individuals), presymptomatic (for individuals at risk), and prenatal (for pregnancies at risk).

RESULTS

A total of 3,090 HD patients, 992 individuals at risk, and 24 fetuses were investigated using DNA analysis. The clinical diagnosis was confirmed in 65.6% of patients. A total of 38.5% of individuals at risk inherited an expanded CAG repeat. The female-to-male ratio showed a distinct predominance of women both in the diagnostic and presymptomatic groups. Of the fetuses tested, six were carriers of an expanded CAG repeat. Two pregnancies were interrupted; one pregnancy was not. No information about the parents' decision was obtained for the remaining three pregnancies.

CONCLUSIONS

Approximately 20% of the estimated 10,000 HD patients living in Germany, Switzerland, and Austria have been identified by DNA analysis (total population, approximately 100 million; incidence of HD, 1:10,000). Assuming a ratio of HD patients to individuals at risk of 1:3, approximately 30,000 individuals are, in principle, eligible for a presymptomatic test. Less than 3 to 4% of individuals at risk have requested a presymptomatic test. This shows that the assumed enormous request of predictive testing has not occurred. More surprisingly, prenatal diagnoses were found to be rare.

Different mechanisms for the photoinduced production of oxidative DNA damage by fluoroquinolones differing in photostability

Several fluoroquinolone antibacterial agents exhibit an adverse phototoxic effect in humans and are photo-cocarcinogenic in mice. The UV-induced production of reactive oxygen species plays a role in the toxicity and may be involved in carcinogenicity. Four fluoroquinolones were examined for the ability to photochemically produce oxidative damage in naked DNA. The major structural difference in the fluoroquinolones that would have an effect on their photostability is the functionality at the 8-position. At this position, 1-cyclopropyl-7-(2,8-diazbicyclo[4.3.0]non-8-yl)-6, 8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid (BAY y3118) contains a chlorine atom, lomefloxacin a fluorine atom, ciprofloxacin a proton, and moxifloxacin a methoxy group. The formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in calf thymus DNA was assessed by HPLC with electrochemical detection, and strand breaks were measured in pBR322 with agarose gel electrophoresis. The relative photolability of the fluoroquinolones correlated to the extent of production of 8-oxodGuo and strand breaks, with both UVA and UVB irradiation, in the following order: BAY y3118 approximately lomefloxacin > ciprofloxacin > moxifloxacin. Experiments were performed to determine whether the mechanism of damage was due to a type I (radical) or type II (singlet oxygen) pathway. Nitrogen depletion of oxygen resulted in a decrease in the extent of formation of 8-oxodGuo, suggesting that oxygen was involved. The use of selective radical or singlet oxygen inhibitors was inconclusive with respect to which pathway was involved. The use of D(2)O as a solvent, which would extend the lifetime of singlet oxygen, suggested that this species is involved in the formation of 8-oxodGuo by moxifloxacin and ciprofloxacin, but not by lomefloxacin and BAY y3118. Similarly, it was found that singlet oxygen was not involved in strand break formation. Thus, the evidence suggests that fluoroquinolones can photochemically produce DNA damage by both type I and type II mechanisms.

Urinary antigens as markers of papillary toxicity. II: Application of monoclonal antibodies for the determination of papillary antigens in rat urine

We have previously reported the preparation of monoclonal antibodies specific for antigens localized in the rat renal papilla. Three of the monoclonal antibodies reacting with antigens localized in papillary and cortical collecting duct epithelia were selected for the development of enzyme-linked immunosorbent assay (ELISA)-type assays. The papillary antigens ('PapA') determined in these tests were designated PapAl (applying the monoclonal antibody PapX 5C10), PapA2 (applying the monoclonal antibody PapX 12F6), and PapA3 (applying the monoclonal antibody PapXI 3C7). Using these assays antigen excretion was determined in the urine of rats. Depending on the test compound used. the application route, and the dose, the observed antigen release patterns differed. Whereas after a single intraperitoneal application of 2-bromoethanamine or of propyleneimine an increased release of PapA1 but not of the two other antigens was observed oral application of bromoethanamine had minor effects. In contrast, both a single intraperitoneal application or repeated oral applications of indomethacin resulted in an increased release of all the three antigens. Daily application of ipsapirone in the diet or in drinking water resulted in significantly elevated urinary release of PapAl which increased incrementally for the duration of the application. Release of PapA2 and PapA3 was not affected and remained in the normal range. These results show that with the tests developed changes in the rat renal papilla caused by xenobiotics can be detected early by urinary analysis and monitored during follow-up studies. Moreover. the different antigen release patterns obtained after application of the different compounds suggest a possible differing mode of action.

Preclinical safety evaluation of moxifloxacin, a novel fluoroquinolone

The toxicity of moxifloxacin (BAY 12-8039), a novel fluoroquinolone with a broad spectrum of antibacterial activity, was evaluated in a comprehensive programme of toxicological studies that included single and multiple dose toxicity studies in rats, mice, dogs and monkeys, reproductive system toxicity studies in rats and monkeys and in-vitro and in-vivo mutagenicity assays. Although moxifloxacin is not intended for long-term clinical use, an accelerated bioassay in target organs to assess carcinogenesis was performed in rats. In addition to the routine toxicological programme required for the development of a drug intended for short-term administration, a major part of the preclinical programme for moxifloxacin comprised studies designed specifically to address the safety issues known to be features of fluoroquinolones, i.e. adverse effects on the central nervous and cardiovascular systems, phototoxicity, arthrotoxicity and oculotoxicity. The results of the toxicological investigations confirmed that the safety profile of moxifloxacin is comparable to those of other fluoroquinolones.

Damage to mitochondrial DNA induced by the quinolone Bay y 3118 in embryonic turkey liver

Quinolones are a class of antibiotics that induce damage to and loss of DNA from bacteria. The structural organization of bacterial DNA is more similar to eukaryotic mitochondrial DNA (mtDNA) than to eukaryotic chromosomal or nuclear DNA (nDNA). Antibiotics affecting the bacterial genome may therefore preferentially damage mtDNA rather than nDNA. We investigated the effect of a quinolone on mtDNA in avian embryonic hepatocytes in ovo. The quinolone Bay y 3118 (1-cyclopropyl-7-(2,8-diazabicyclo[4.3.0]non-8-yl) 6-fluoro-8-chloro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid hydrochloride, chemical structure see Bremm et al. [K.D. Bremm, U. Petersen, K.G. Metzger, R. Endermann, In vitro evaluation of Bay-y 3118, a new full-spectrum fluoroquinolone, Chemotherapy 38 (1992) 376-387] was injected into fertilized turkey eggs 8 days before hatching at doses of 1, 3, 10 and 30 mg per egg. The embryos were removed from the eggs after 4 days and liver samples were shock frozen. Mitochondrial DNA was purified from samples of the embryonic liver. The integrity of mtDNA was investigated by electrophoresis on agarose gels with native mtDNA and with ribonuclease-treated mtDNA. Fluorescent staining of the electrophoresis gels allows the densitometric quantification of the mtDNA of the regular band at 16 kilobases (kb) and the amount of DNA fragments of irregular size (smear). The genotoxic nitrosamine nitrosodiethylamine (NDEA) has previously been shown to reduce the content of mtDNA of the regular size of 16 kb and to induce the occurrence of smaller fragments of mtDNA [H. Enzmann, C. Kühlem, E. Löser, P. Bannasch, Damage to mitochondrial DNA induced by the hepatocarcinogen, diethylnitrosamine in ovo, Mutation Res. 329 (1995) 113-120]. After exposure to 10 and 30 mg Bay y 3118, a dose-dependent induction of damage to the mtDNA was found, whereas exposure to 3 and 1 mg showed no effect. NDEA (25 mg) was used as positive control. Testing chemical compounds in the in ovo model is a simple and rapid approach for investigations on chemically induced alterations of mtDNA.

Preclinical safety evaluation of cerivastatin, a novel HMG-CoA reductase inhibitor

Cerivastatin is a new but structurally distinct 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor ("statin"). It effectively decreases low-density lipoprotein (LDL) cholesterol at 1% of the doses of other currently available statins. The toxicology of cerivastatin was evaluated in a comprehensive program of studies including: (1) single- and multiple-dose toxicity studies in rats, mice, minipigs, dogs, and monkeys; (2) reproductive toxicity studies in rats and rabbits; (3) in vitro and in vivo mutagenicity assays in rats and mice; and (4) carcinogenicity studies in rats and mice. In addition, studies were undertaken to investigate the effects of cerivastatin on lens opacity, testicular tissue, and hemorrhage in dogs. Oral administration of single and multiple doses of cerivastatin over periods ranging from 4 weeks to 24 months was generally well tolerated. Adverse effects were similar to those observed with other statins and primarily involved the liver and muscle tissue. At the high doses used in the toxicologic studies, cerivastatin caused elevations in serum transaminases and creatine phosphokinase levels as well as some degeneration of muscle fibers in rats, mice, dogs, and minipigs. In dogs, the species most sensitive to statins, cerivastatin caused erosions and hemorrhages in the gastrointestinal tract, bleeding in the brain stem with fibroid degeneration of vessel walls in the choroid plexus, and lens opacity. Apart from minor morphologic changes in the testicular tissue of dogs--the only organ for which a comparably low margin of safety was observed--cerivastatin had no significant effects on the male or female reproductive system. Cerivastatin also caused no primary embryotoxic or teratogenic effects. With the exception of cerivastatin-induced effects on the eyes and testicles, administration of mevalonic acid reversed the toxicologic effects of cerivastatin, indicating that the toxic effects were related to its mode of action and not to any intrinsic toxicity of the molecule itself. There was no evidence that cerivastatin had any mutagenic effects and, in contrast to other statins, high doses of cerivastatin did not induce tumors in rats. The main metabolite of cerivastatin was well tolerated systemically in all animals, including dogs. Overall, cerivastatin has a similar toxicologic profile to other statins and is a well-tolerated HMG-CoA reductase inhibitor.

Determination of the excitatory potencies of fluoroquinolones in the central nervous system by an in vitro model

Fluoroquinolones have been reported to induce central nervous system side effects, including seizures and psychiatric events. Although relatively rare in patients up to now, the proconvulsant activity depends on the chemical structure and might be a critical endpoint of some new representatives of this valuable class of antimicrobials. The electrophysiological determination of field potentials in the CA1 region of the rat hippocampus slice allowed an assessment of the excitatory potential of fluoroquinolones and might be predictive for their neurotoxic potency in vivo. An optimization of this method and its extension to other fluoroquinolones resulted in a defined rank order. Well-known already-marketed quinolones as well as some fluoroquinolones under evaluation and development were used. The dose range tested was between 0.5 and 4 mumol/liter, which was comparable to the therapeutic concentration in the brain. All tested compounds increased the population spike amplitude in a concentration-dependent manner, and the resulting excitatory potency was highly dependent on the chemical structure, with compounds ranging from least to most excitatory as follows: ofloxacin, ciprofloxacin, nalidixic acid, moxifloxacin, BAY x 8843, [corrected] fleroxacin, lomefloxacin, enoxacin, clinafloxacin (much more excitatory than enoxacin), tosufloxacin, trovafloxacin, BAY 15-7828, and BAY x 9181 (much more excitatory than BAY 15-7828). The proposed hippocampus slice model not only is suitable for giving valuable alerts as to convulsive potential during candidate selection but also enables mechanistic investigations. These investigations pointed to the N-methyl-D-aspartate receptor as the probable target of the fluoroquinolone effects.

Calcium channel blockers and the risk of cancer: a preclinical assessment

The preclinical evidence for a potential influence of calcium channel blockers (CCBs) on carcinogenesis is discussed in the light of a broad database from rodent carcinogenicity studies as well as literature data. In all bioassays performed in rats and mice on the dihydropyridine CCBs--nifedipine, nimodipine, nisoldipine, and nitrendipine--no evidence was found for a carcinogenic potential of these compounds. Calcium is an essential intracellular signal for cell proliferation and apoptosis. The crucial role of increased cell proliferation in all stages of carcinogenesis is well documented. Some indirect experimental evidence also points to a role of defective apoptosis in tumor promotion. CCBs uniformly inhibit cell proliferation, whereas the influence of CCBs on apoptosis is inconsistent, resulting in an inhibition or increase in apoptosis dependent on cell type. Accordingly, antitumorigenic effects of CCBs have been reported based on their antiproliferative action. A tumor-promoting effect of CCBs based on inhibition of apoptosis, however, remains purely speculative and, in fact, can be denied based on the results of in vivo bioassays. It is therefore concluded that there is no preclinical evidence that should give rise to concern over the carcinogenic potential of dihydropyridine-type CCBs.

Calcium channel blockers and cancer: is there preclinical evidence for an association?

The preclinical evidence for a potential influence of calcium channel blockers (CCB) on carcinogenesis is discussed in the light of rodent carcinogenicity studies as well as mechanistic data. In the bioassays performed in rats and mice on the dihydropyridine CCB nifedipine, nimodipine, nisoldipine and nitrendipine, no evidence was found for a carcinogenic potential of these compounds. Moreover, the mechanistic knowledge on the influence of CCB on the fundamental processes of cell proliferation and apoptosis is not in favor of a tumor-promoting activity of these compounds. It is, therefore, concluded that there is no preclinical evidence that the therapeutic use of CCB of the dihydropyridine class is associated with an increased risk of cancer.

Quinolone antibiotic photodynamic production of 8-oxo-7, 8-dihydro-2'-deoxyguanosine in cultured liver epithelial cells

To study the basis for the phototoxicity of quinolones, a class of synthetic antibacterials, the photodynamic ability to mediate 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) formation in cultured cells was measured for lomefloxacin (LMX), which is strongly associated with clinical phototoxicity in humans, and ciprofloxacin (CFX), which has few reports of phototoxicity. Adult rat liver (ARL-18) cells were exposed to the quinolones in the presence of UVA and DNA was extracted and analyzed by HPLC with electrochemical detection. Low levels of 8-oxo-dG were found in the DNA of nonirradiated ARL-18 cells and this was increased up to 6-fold in the presence of either LMX (50-400 microM) or up to 3.6-fold in the presence of CFX (50-400 microM) and UVA (20 J/cm2) when compared to the UVA control. Comparing separate experiments with LMX and CFX, LMX produced greater levels of 8-oxo-dG either after dark exposure or after UVA exposure at 20 J/cm2. Also, LMX and CFX were both shown to photodegrade in the presence of UVA, and it was determined that UVA photoinstability alone does not reflect phototoxic potential. These data suggest that the photodynamic potential of LMX and CFX to produce 8-oxo-dG may relate to their human clinical phototoxicity profile. We suggest that the observed clinical phototoxicity is mediated through a UVA photodynamic effect on the quinolone to form reactive oxygen species in the presence of molecular oxygen. The findings indicate that 8-oxo-dG formation can serve as a marker for the potential phototoxicity of new quinolones.

Specific binding of a 47-kilodalton protein to the 3' untranslated region of rat transition protein 2 messenger ribonucleic acid

The synthesis of transition protein (TNP) 2, one of the predominant nuclear proteins of mammalian spermatids, was shown to be posttranscriptionally regulated, by storing the untranslated mRNA for about 3-5 days in the cytoplasm of differentiating spermatids. It has been proposed that binding of a cytoplasmic protein to a conserved motif of 8 nucleotides (nt) in the 3' untranslated region (3'UTR) of TNP2 mRNA is involved in this translational control mechanism. In this report, we show that deletion or variation of the conserved 8-nt motif (GCCAT-CAC) in rat TNP2-3'UTR abolishes the capacity of the in vitro-transcribed RNA to reconstitute specific RNA-protein complexes in RNA bandshift assays. Using Northwestern analysis, we identified specific binding to the TNP2-3'UTR of four proteins of 45, 47, 49, and 60 kDa, all of which are stage-specifically regulated in male germ cell differentiation. Deletion of the 8-nt motif in the 3'UTR specifically prevented binding of the 47-kDa protein, the interaction of which is thought to be mediated by the RNA secondary structure. Analysis of the RNA secondary structure revealed that the 8-nt motif is an essential element of a specific stem-loop structure that is predicted for rat wild-type TNP2-3'UTR. Therefore we assume that the 47-kDa protein plays an important role in specific RNA-protein complex formation of rat TNP2-3'UTR that may be a central event in the translational control of rat TNP2 mRNA.

An in vitro model for toxicological investigations of environmental neurotoxins in primary neuronal cell cultures

Currently, most neurotoxicological investigations are still conducted using various animal models (e.g. chickens, rodents). In this report, alternative strategies of testing were examined to detect the neurotoxic potency of foreign compounds. Primary neuronal cell cultures from fetal rats are already an accepted model for mechanistic and pharmacological studies in drug research. Their suitability for neurotoxicological studies was examined by using industrial model compounds, which are well-known inductors of neuropathies: acrylamide, hexachlorophene, paraquat, n-hexane, and its neurotoxic metabolites acetylaceton and 2,5-hexandione. As a control compound, the nonneurotoxic solvent n-heptane was used. General cytotoxicity and the intracellular content of glial fibrillary acid protein, neuron-specific enolase, and neurofilaments were measured. n-Heptane induced an acute cytotoxicity and acrylamide and 2,5-hexandione produced a delayed cytotoxicity in primary neuronal cells, whereas the others showed no cytotoxic potency in the tested concentration range. These results were in agreement with the quantification of neurons by neuron-specific enolase. In contrast, with the exception of acetylaceton, glia cells were significantly affected by all neurotoxins at the later time. Signs of axonopathies were demonstrated for acrylamide, n-hexane and its metabolites, as well as for hexachlorophene and paraquat in vitro, by determining the intracellular neurofilament level. Therefore, the determination of cell-specific end points is necessary to detect the neurotoxic potency and quality of a compound, whereas the cytotoxicity assay limited the tested concentration range.

Stage and developmental specific gene expression during mammalian spermatogenesis

Spermatogenesis is a complex developmental process which involves amplification of germinal stem cells, their differentiation into spermatocytes, meiotic division and finally transformation into mature spermatozoa. Therefore, spermatogenesis provides an interesting system for examining the regulation of gene expression during development and differentiation. The genes expressed during spermatogenesis can be divided into two main groups: diploid and haploid expressed genes. In this review, we report about the regulation of expression of a diploid expressed gene, namely the proacrosin gene, and that of a haploid expressed gene, the transition protein 2 gene.

Urinary antigens as markers of papillary toxicity. I. Identification and characterization of rat kidney papillary antigens with monoclonal antibodies

Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the rat renal papilla. One IgG and five IgM monoclonal antibodies, reacting with antigens localized in the papilla were obtained. Three of the IgM class and the IgG class monoclonal antibodies were found to be specific for antigens localized in collecting ducts, two of them staining papillary collecting ducts more intensely than cortical collecting ducts. The IgG class antibody, termed Pap X 5C10, recognizes an antigen located at high density on the luminal side of papillary collecting duct epithelial cells and at lower density in cortical collecting duct cells. One of the IgM class monoclonal antibodies reacts with an antigen localized in epithelial cells as ascending and descending loops of Henle and of connecting tubules. Another of the IgM class monoclonal antibodies reacts with an antigen localized in the interstices of the inner medulla. All these monoclonal antibodies react with their antigens in native frozen as well as in Bouin-fixed and paraffin-embedded tissue slices. Molecular properties of the Pap X 5C10 antigen have been investigated by gel permeation chromatography, SDS-PAGE, Western blotting, and isoelectric focusing. The results indicate that the antigen in both its tissue-derived and urinary form is of large (150-200 kDa) molecular size and can be separated into two molecular species with isoelectric points of pH 7.2 and 7.3 respectively. In the urine the antigens recognized by the monoclonal antibodies form large complexes with Tamm-Horsfall protein. The antigen-containing complexes can be extracted from urine by adsorption to diatomaceous earth and elution with SDS-containing buffer. Using sandwich ELISA-type assays it is possible to determine the concentration of the antigens. In preliminary experiments we were able to show that at least three of the antigens are detected in the urine following toxic insults to the kidney. The monoclonal antibodies prepared and the tests developed thus may provide direct diagnostic access to the renal papilla and allow, for the first time, early detection of papillary damage.

Sequence analysis of the conserved protamine gene cluster shows that it contains a fourth expressed gene

Structural data are presented on the protamine gene cluster (PGC) of human, mouse, rat, and bull. By restriction mapping we demonstrate that the organization of the protamine cluster is conserved throughout all four species, i.e., the genes are situated in a head to tail arrangement in the order: protamine 1-protamine 2-transition protein 2. Further, we established the nucleotide sequence of the entire human PGC (25 kb in total) and the 3' portion of the rat protamine cluster (PRM2 and TNP2 genes and intergenic region). In addition, a 1 kb fragment of the bovine and murine protamine cluster, situated between PRM2 and TNP2, was sequenced. This fragment is conserved regarding sequence, position, and orientation in all species examined, and was classified as likely coding region by gene recognition program GRAIL. Using the rat fragment as a probe in RNA blots, we detected a testis-specific signal of about 0.5 kb. Finally, we demonstrate a high density of Alu elements, both full and fragmented copies, in the human PGC and discuss their localization with respect to evolutionary and functional aspects.

The rat Prm3 gene is an intronless member of the protamine gene cluster and is expressed in haploid male germ cells

We have cloned and sequenced the cDNA of a novel gene from the rat protamine gene cluster. This gene, preliminarily referred to as Prm3, is intronless and resides between the genes for protamine 2 and transition protein 2. Prm3 is transcribed from the same strand as these genes and is expressed in haploid stages of spermatogenesis. The 410-bp-long cDNA possesses an ORF, coding for a putative 104-amino acid polypeptide with a high content of glutamic acid.

Electrically evoked potentials in the rat hippocampus slice in the presence of aminophylline alone and in combination with quinolones

The excitability of brain matter was tested bt electrically evoked field potentials in the CA1 region of the rat hippocampus in vitro. In contrast to the quinolones which only increased the amplitudes of electrically evoked potentials, aminophylline induced spontaneous firing in the pyramidal cell layer without stimulation in addition to its dose-dependent effects on the amplitudes of the evoked potentials. Threshold doses of the quinolones tested (0.25 microM) increased the amplitudes of evoked potentials in the presence of an otherwise ineffective concentration of aminophylline (0.5 microM) to different degrees, ranging from 135.3% for ciprofloxacin to 223.8% for nalidixic acid. The rank order of potency of CNS side effects reported in the literature correlates very well with the increase of the population spike amplitude in the hippocampus slice preparation. This feature could be important during the development of new chemical analogues of quinolones.

An 87 bp deletion in exon 5 of the LDL receptor gene in a mother and her son with familial hypercholesterolemia

DNA analysis of the low density lipoprotein receptor (LDLR) gene was performed in two persons with familial hypercholesterolemia (FH). Southern blot experiments indicated the heterozygous loss of an EcoRI site in exon 5 of the LDLR gene. Upon amplification and sequencing of exon 5 in both probands, an 87-bp deletion in a heterozygous state could be evaluated. This is a novel mutation, most probably leading to the formation of a nonfunctional LDLR. Analysis of the deletion breakpoints revealed the presence of a six-base-pair consensus sequence 5'TGA/GA/GG/TA/C3', which is characteristic of small deletions in different genetic defects.

A conserved 8 bp motif (GCYATCAY) in the 3'UTR of transition protein 2 as a putative target for a transcript stabilizing protein factor

The 3'UTR of the transition protein 2 gene of several mammalian species was sequenced and the transcript level of this gene was determined by Northern blots. In all species tested so far, a Northern blot detectable transcript level was associated with the presence of a conserved 8 bp motif (GCYATCAY) 50 bp downstream of the stop codon. RNA-bandshift experiments indicate that this region is capable of binding a cytosolic protein factor from rat testis. These findings support our hypothesis that the low transcript level of the transition protein 2 gene in human is due to insufficient storage of the mRNA as ribonucleic/protein particle.

Chondrotoxicity of quinolones in vivo and in vitro

Chondrotoxicity is a rare toxicological finding which is observed in dogs after administration of quinolone antibacterials. To study this effect chondrocytes from articular cartilage of dogs were isolated, and incubated with quinolone derivatives. The effects on cell viability, mitochondrial dehydrogenase, and proteoglycan synthesis were determined. These results were compared with in vivo findings in dogs treated with these quinolones. It was concluded that inhibition of mitochondrial dehydrogenase activity and of proteoglycan synthesis are major reasons for cartilage damage. Therefore this in vitro model is capable of identifying strongly arthropathogenic quinolones without the need of performing animal studies.

The gene for human transition protein 2: nucleotide sequence, assignment to the protamine gene cluster, and evidence for its low expression

We have isolated the gene for transition protein 2 (TNP2) from a human cosmid clone that contains the genes for protamines 1 and 2. A nucleotide sequence of 1776 bp that comprises 268 bp of the 5'-noncoding region, 400 bp of exon 1, 849 bp of an intron, 17 bp of exon 2, and 242 bp of the 3'-noncoding region was determined. A modified CAT box, a TATAA box, and two possible polyadenylation sites were identified. Transcripts in testicular RNA could be detected only by RT-PCR and RNase protection assays. By direct sequencing of the PCR products, a cDNA sequence was established. It can be deduced from these results that, in contrast to other mammalian genes, the human TNP2 gene is expressed at a very low level. The human gene differs from that of other mammalian species by the absence of a conserved GCCATCAC nucleotide sequence in the 3'-untranslated region. Since both protamine genes are known to be localized on chromosome 16p13.3, this chromosomal localization holds true for the human TNP2 gene as well. The genes for both protamines and TNP2 are arranged in a DNA stretch of 13 kb.

The genes for protamine 1 and 2 (PRM1 and PRM2) and transition protein 2 (TNP2) are closely linked in the mammalian genome

The genes for two protamines (PRM1 and PRM2) and for two transition proteins (TNP1 and TNP2) have been characterized in several mammalian species. In the human, boar, and bull, the genes for PRM1, PRM2, and TNP2 are closely linked over a stretch of DNA 13-15 kb long. Although similar data are not yet available for the mouse and rat, our results suggest that the three genes are similarly linked in these species. The gene for TNP1 in all species studied is located on another chromosome.