Mapping and genomic characterization of the gene encoding diacylglycerol kinase gamma (DAGK3): assessment of its role in dominant optic atrophy (OPA1)

The family of diacylglycerol kinases (DAGKs) is known to play an important role in signal transduction linked to phospholipid turnover. In the fruitfly Drosophila melanogaster, a human DAGK ortholog, DGK2, was shown to underlie the phenotype of the visual mutant retinal degeneration A (rdgA). Previously, the gene encoding a novel member of the human DAGK family, termed DAGK3, was cloned and demonstrated to be abundantly expressed in the human retina. Based on these findings we reasoned that DAGK3 might be an excellent candidate gene for a human eye disease. In the present study, we report the genomic organization of the human DAGK3 gene, which spans over 30 kb of genomic DNA interrupted by 23 introns. In addition, we have mapped the gene locus by fluorescence in situ hybridization to 3q27-28, overlapping the chromosomal region known to contain the gene underlying dominant optic atrophy (OPA1), the most common form of hereditary atrophy of the optic nerve. Mutational analysis of the entire coding region of DAGK3 in 19 unrelated German OPA1 patients has not revealed any disease-causing mutations, therefore excluding DAGK3 as a major cause underlying OPA1.

Prevalence of human papilloma virus DNA in head and neck cancers carrying wild-type or mutant p53 tumor suppressor genes

The normal function of the p53 tumor suppressor protein can be perturbed by non-mutational mechanisms. The E6 protein encoded by high risk strains of human papilloma virus (HPV) targets the p53 protein resulting in enhanced degradation via the ubiquitin pathway. We have used nested PCR for detecting the presence of HPV DNA in 58 primary head and neck tumors and 15 metastatic lymph nodes, which had been prescreened for p53 mutations in exons 5 to 8. HPV DNA sequences were detected in 12 tumors (20.6%) and 4 metastatic lymph nodes (21%). HPV type 16 DNA was predominantly found in tumors (n = 11) and lymph nodes (n = 4), one tumor was positive for HPV type 18 sequences. Five of 12 HPV-positive tumors (41%) carried a p53 mutation. Of 46 HPV-negative tumors, 16 (34.8%) carried a p53 mutation. Thus, HPV positivity and p53 mutations were not mutually exclusive in head-and-neck cancer. Three of 6 normal tissues adjacent to the tumor were positive for HPV type 16, while no viral DNA was found in the corresponding tumors. Thus, the presence of HPV type 16 DNA did not directly confer a growth advantage on the population of emerging tumor cells. Instead, these tumors lack normal p53 function due to mutation.

[Proliferating trichilemmal cyst with focal segments of metastatic squamous epithelial carcinoma]

A large ulcerated tumor covered the right hemisphere of the scalp of a 77 year old woman. By histological, immunohistological, and electronmicroscopical examination, a proliferating trichilemmal cyst with focal areas of a poorly differentiated squamous cell carcinoma was identified. Six months after extirpation of the entire tumor and dissection of supraomohyoidal lymph nodes, metastases in nuchal and supraclavicular lymph nodes and soft tissue of the neck became apparent. The present case underlines the necessity of a preoperative diagnostic evaluation and of radical surgical treatment for proliferating trichilemmal cysts.

Homozygous deletions of methylthioadenosine phosphorylase (MTAP) are more frequent than p16INK4A (CDKN2) homozygous deletions in primary non-small cell lung cancers (NSCLC)

Homozygous deletions of the tumor suppressor gene p16INK4A and deficiency of methylthioadenosine phosphorylase (MTAP), both located on chromosome 9p21, have been independently reported in non-small cell lung cancer (NSCLC). To determine the frequency of co-deletion of these two genes, we investigated 50 samples of primary NSCLC using a quantitative PCR-ELISA. All specimens were fixed in formalin, paraffin embedded and stored until assayed. Histologic subtypes included 25 adenocarcinomas (50%), 21 squamous cell carcinomas (42%) and four large cell carcinomas (8%). Homozygous deletions of MTAP exon 8 could be detected in 19 of 50 NSCLC samples (38%). Adenocarcinoma (11 of 25, 44%) showed a higher deletion frequency than squamous cell carcinoma (six of 21, 29%). In contrast, homozygous p16INK4A deletions were detected in only nine of 50 (18%) samples using specific primers for p16INK4A exon 1alpha. No difference between the histological subtypes and p16INK4A deletion frequency was observed. We further investigated the ten samples with MTAP deletions but intact p16INK4A exon 1alpha with primers specific for p16INK4A exon 3, the exon nearest to MTAP exon 8. Interestingly, none of the ten samples had deletion of the p16INK4A exon 3 coding region. Fine mapping analysis performed in ten samples showed a frequent breakpoint between MTAP exon 4 and exon 5. In addition, p16 protein expression could not be detected in five out of six samples with intact p16 but deleted MTAP locus. These data show a high frequency of homozygous MTAP deletions in NSCLC which is associated with detectable co-deletion of p16INK4A in only half of the cases. This result suggests the existence either of another tumor suppressor gene telomeric of p16INK4A or of deletions involving 3'-untranslated (3'-UTR) regulatory regions of p16INK4A that can interfere with its expression or function.

The plant PTS1 receptor: similarities and differences to its human and yeast counterparts

Two targeting signals, PTS1 and PTS2, mediate import of proteins into the peroxisomal matrix. We have cloned and sequenced the watermelon (Citrullus vulgaris) cDNA homologue to the PTS1 receptor gene (PEX5). Its gene product, CvPex5p, belongs to the family of tetratricopeptide repeat (TPR) containing proteins like the human and yeast counterparts, and exhibits 11 repeats of the sequence W-X2-(E/S)-(Y/F/Q) in its N-terminal half. According to fractionation studies the plant Pex5p is located mainly in the cytosolic fraction and therefore could function as a cycling receptor between the cytosol and glyoxysomes, as has been proposed for the Pex5p of human and some yeast peroxisomes. Transformation of the Hansenula polymorpha peroxisome deficient pex5 mutant with watermelon PEX5 resulted in restoration of peroxisome formation and the synthesis of additional membranes surrounding the peroxisomes. These structures are labeled in immunogold experiments using antibodies against the Hansenula polymorpha integral membrane protein Pex3p, confirming their peroxisomal nature. The plant Pex5p was localized by immunogold labelling mainly in the cytosol of the yeast, but also inside the newly formed peroxisomes. However, import of the PTS1 protein alcohol oxidase is only partially restored by CvPex5p.

Mouse homolog of the yeast origin recognition complex subunit ORC1 and chromosomal localization of the cognate mouse gene Orc1

ORC1 encodes a subunit of the eukaryotic origin recognition complex in yeast, which has been shown to play a crucial role in chromosomal DNA replication and transcriptional silencing. We have identified a mouse protein closely related to Saccharomyces cerevisiae ORC1 as well as to the human, Xenopus and Drosophila homologs. MmORC1 has putative cyclin-dependent phosphorylation sites and a nucleotide triphosphate-binding motif. We have mapped the gene locus of the murine Orc1 gene to chromosome 4, band D. Conservation of structures among members of the ORC1-related proteins suggests that these proteins play a key role in the intiation of DNA replication in all eukaryotes.

Atrial fibrillatory electrogram measurement allows atrial lead placement in patients who develop atrial fibrillation during permanent dual chamber pacemaker implantation

The benefit of DDD(R) pacing is proven even in patients with intermittent atrial fibrillation. Atrial fibrillation developing during dual chamber pacemaker implantation creates a difficult problem. Maneuvers to reestablish a stable atrial rhythm often are required if atrial fibrillation sets in. This study was performed to determine if atrial lead placement can be performed with acceptable long-term results in the presence of atrial fibrillation. Twenty-one patients in whom atrial fibrillation developed during permanent pacemaker implantation were included in this study. In 12 patients, episodes of intermittent atrial fibrillation had been documented before the procedure. Screw-in leads were used in 15 patients and J-shaped passive fixation leads in 6 patients. All leads were bipolar. The intraoperative atrial fibrillation electrogram amplitudes ranged from 0.9 to 3.2 mV (mean 1.8 +/- 0.6 mV). One patient required lead revision due to a high atrial pacing threshold after conversion to SR. One patient remained in atrial fibrillation at 3-month follow-up. The other 20 patients converted to SR, 11 of whom had intermittent atrial fibrillation with successful mode switch activation. P wave amplitudes were 2.8 +/- .6 mV (range 1.4 to 4.0 mV) after conversion to SR. The mean atrial pacing threshold was 1.1 +/- 0.5 V (range 0.5 to 3.5 V). Placement of atrial leads in patients who develop atrial fibrillation during pacemaker implantation is feasible; fibrillatory electrogram amplitudes showed a good correlation with the atrial signal after conversion to an organized atrial rhythm (r = 0.698). Acceptable atrial pacing thresholds can be expected as well.

[Value of liver histology in diagnosis of chronic hepatopathies]

The importance of a liver biopsy is summarized as follows: 1. A diagnostic liver biopsy may be helpful in otherwise unexplained liver disease, especially in cases with controversial or unexplicable patterns of laboratory findings or in chronic hepatitis without positive serological markers. 2. Liver histology is necessary for the assessment of the necroinflammatory activity of chronic hepatitis in order to decide on an eventual therapy. Liver biopsy is an important tool as well for the evaluation of liver transplantation in the end stage of several liver diseases as for the diagnosis of transplant-complications. 3. Follow-up biopsies are necessary for supervision of therapy of chronic hepatitis. Histology is the only reliable method for assessment of necroinflammatory activity.

A cysteine endopeptidase with a C-terminal KDEL motif isolated from castor bean endosperm is a marker enzyme for the ricinosome, a putative lytic compartment

A papain-type cysteine endopeptidase with a molecular mass of 35 kDa for the mature enzyme, was purified from germinating castor bean (Ricinus communis L.) endosperm by virtue of its capacity to process the glyoxysomal malate dehydrogenase precursor protein to the mature subunit in vitro (C. Gietl et al., 1997, Plant Physiol 113: 863-871). The cDNA clones from endosperm of germinating seedlings and from developing seeds were isolated and sequence analysis revealed that a very similar or identical peptidase is synthesised in both tissues. Sequencing established a presequence for co-translational targeting into the endoplasmic reticulum, an N-terminal propeptide and a C-terminal KDEL motif for the castor bean cysteine endopeptidase precursor. The 45-kDa pro-enzyme stably present in isolated organelles was enzymatically active. Immunocytochemistry with antibodies raised against the purified cysteine endopeptidase revealed highly specific labelling of ricinosomes, organelles which co-purify with glyoxysomes from germinating Ricinus endosperm. The cysteine endopeptidase from castor bean endosperm, which represents a senescing tissue, is homologous to cysteine endopeptidases from other senescing tissues such as the cotyledons of germinating mung bean (Vigna mungo) and vetch (Vicia sativa), the seed pods of maturing French bean (Phaseolus vulgaris) and the flowers of daylily (Hemerocallis sp.).

Inhibition of condensation in human chromosomes induced by the thymidine analogue 5-iododeoxyuridine

Human lymphocyte cultures were treated with iododeoxyuridine. This 5-halogenated thymidine analogue induces distinct undercondensations of the heterochromatin of human chromosome 9. The condensation of the other heterochromatic regions on chromosomes 1, 15, 16 and Y is also inhibited, but to a lesser extent. Optimum cell culture conditions required for the induction of undercondensations were determined. Up to 90% of mitotic cells reveal chromosome 9 heterochromatin decondensations when the substance is present in quantities of 1 x 10(-4) M during the last 7 h before cell fixation. In addition, examples of the usefulness of 5-IUDR in the analysis of chromosome aberrations involving chromosome 9 are presented. The interaction between 5-IUDR and chromosomal DNA, the modification of chromosomal proteins and factors inducing chromosomal decondensations are discussed.

Alteration of HLA-B27 peptide presentation after infection of transfected murine L cells by Shigella flexneri

Shigella flexneri is a triggering agent for reactive arthritis in HLA-B27-susceptible individuals. Considering the intracellular multiplication of bacteria, it seems likely that bacterial peptides may be presented by the major histocompatibility complex (MHC) class I pathway. To examine this hypothesis, we infected HLA-B*2705- and/or human beta2-microglobulin-transfected murine L-cell lines with M90T, an invasive strain of S. flexneri. Bacterial infection induced no detectable modifications in the biosynthesis and expression level of HLA-B27, as assessed by immunoprecipitation, Northern blot analysis, and flow cytometry. Using confocal microscopy, we observed that bacterial infection induced a clustering of HLA-B27 molecules during macropinocytosis and before bacterial dissemination from cell to cell. Peptides naturally bound to HLA-B27 molecules were acid eluted from infected cells and separated by high-performance liquid chromatography. Major differences were observed in high-performance liquid chromatography profiles and in the nature of peptides presented following bacterial infection. Although most of the antigens presented were not accessed by Edman degradation, we obtained two sequences partially homologous to bacterial proteins. These peptides lacked the major HLA-B27 peptide anchor (Arg) at position 2, and one had an unusual length of 14 amino acids. These data suggest that alterations in the peptide presentation by HLA-B27 occur during infection, which could be relevant to the pathogenesis of HLA-B27-related arthritis.

Combined molecular and conventional analyses of nitrifying bacterium diversity in activated sludge: Nitrosococcus mobilis and Nitrospira-like bacteria as dominant populations

The ammonia-oxidizing and nitrite-oxidizing bacterial populations occurring in the nitrifying activated sludge of an industrial wastewater treatment plant receiving sewage with high ammonia concentrations were studied by use of a polyphasic approach. In situ hybridization with a set of hierarchical 16S rRNA-targeted probes for ammonia-oxidizing bacteria revealed the dominance of Nitrosococcus mobilis-like bacteria. The phylogenetic affiliation suggested by fluorescent in situ hybridization (FISH) was confirmed by isolation of N. mobilis as the numerically dominant ammonia oxidizer and subsequent comparative 16S rRNA gene (rDNA) sequence and DNA-DNA hybridization analyses. For molecular fine-scale analysis of the ammonia-oxidizing population, a partial stretch of the gene encoding the active-site polypeptide of ammonia monooxygenase (amoA) was amplified from total DNA extracted from ammonia oxidizer isolates and from activated sludge. However, comparative sequence analysis of 13 amoA clone sequences from activated sludge demonstrated that these sequences were highly similar to each other and to the corresponding amoA gene fragments of Nitrosomonas europaea Nm50 and the N. mobilis isolate. The unexpected high sequence similarity between the amoA gene fragments of the N. mobilis isolate and N. europaea indicates a possible lateral gene transfer event. Although a Nitrobacter strain was isolated, members of the nitrite-oxidizing genus Nitrobacter were not detectable in the activated sludge by in situ hybridization. Therefore, we used the rRNA approach to investigate the abundance of other well-known nitrite-oxidizing bacterial genera. Three different methods were used for DNA extraction from the activated sludge. For each DNA preparation, almost full-length genes encoding small-subunit rRNA were separately amplified and used to generate three 16S rDNA libraries. By comparative sequence analysis, 2 of 60 randomly selected clones could be assigned to the nitrite-oxidizing bacteria of the genus Nitrospira. Based on these clone sequences, a specific 16S rRNA-targeted probe was developed. FISH of the activated sludge with this probe demonstrated that Nitrospira-like bacteria were present in significant numbers (9% of the total bacterial counts) and frequently occurred in coaggregated microcolonies with N. mobilis.

Histological alterations following short-term smokeless tobacco exposure in humans

The purpose of this study was to investigate the histological changes following short-term smokeless tobacco application in humans. Sixteen smokeless tobacco-using subjects participated in this trial. Each subject had used at least 3 cans of snuff per week for the previous 2 yr and had an existing lesion at the site of habitual snuff placement. The experimental design included subject placement of moist snuff (University of Kentucky reference tobacco brand 1S3) at a new site in the mandibular arch. At either 2 or 7 d, biopsies were taken from the new lesions and from a non-placement site in the opposing arch. The volume density of inflammatory cells was determined by point counting. Keratin and epithelial thickness were evaluated by digitizing morphometry. Data were analyzed by repeated measures analysis of variance. In 7-d lesions, increased keratin thickness was observed at the new sites compared to the non-placement sites (p = 0.05). Increased volume density of fibroblasts (p = 0.027) and decreased volume densities of macrophages (p = 0.0083) and mast cells (p = 0.05) were observed at 2 d in new versus non-placement sites. Clinically, the new sites showed erythema, erythema plus ulceration, or white striations. This study demonstrated histological and clinical changes at new snuff placement sites in as few as 2-7 d, underscoring the rapidity of tissue alterations following snuff use.

Sex chromosome linkage of chicken and duck type I interferon genes: further evidence of evolutionary conservation of the Z chromosome in birds

Type I interferons (IFNs) are a family of proteins that are predominantly expressed in response to viral infection. Two serologically distinct forms of type I IFN, designated ChIFN1 and ChIFN2, have recently been recognized in the chicken. ChIFN1 is encoded by a cluster of ten or more intronless genes, whereas ChIFN2, whose primary sequence is 57% identical, is encoded by a single intronless gene. By fluorescence in situ hybridization we now demonstrate that the genes for ChIFN1 and ChIFN2 are all located on the short arm of the chicken Z chromosome. This assignment was confirmed by results that showed that DNA from male (ZZ) chickens yielded approximately twofold stronger Southern blot signals with ChIFN1 and ChIFN2 hybridization probes than DNA from females (ZW). Attempts to determine differences in IFN production between male and female chickens failed owing to a high degree of variation in virus-induced IFN expression between individuals of both sexes. Sex linkage of IFN genes was also observed in domestic ducks: fluorescence in situ hybridization of duck metaphase chromosomes with a duck type I IFN probe was confined to the terminal region of the long arm of the Z chromosome. Thus, in contrast to mammals, which have their IFN genes on autosomes, birds have the type I IFN genes on the sex chromosome.

[Comparison of methods to characterise thermally altered frying fats and oils]

During the process of deep fat frying the fat or oil undergoes several chemical and physical changes. To guarantee an effective quality control for used frying fats simple and rapid methods for the measurement of heat abuse are needed. Therefore several frying oils were heated with and without foodstuff and the change of polar parts, acid number, colour acid number, specific absorption and dielectric properties with prolonged heating time were determined. It could be shown that under usual frying conditions acid number and colour acid number, which are often used in praxis, as well as the specific absorption are not unrestrictedly useful to characterise heated frying fats. It turned out, however, that the determination of the dielectric properties with a foodoil-sensor is a useful tool to investigate heat abuse of frying fats and oils in routine analysis.

Gamma knife radiosurgery and albendazole for cerebral alveolar hydatid disease

Standard treatment of cerebral alveolar hydatid disease consists of open brain surgery and systemic albendazole. We describe a patient with inoperable cerebral alveolar hydatid cysts on whom gamma knife radiosurgery was used instead of open brain surgery. Because of the size of the multicystic lesion, the gamma knife procedure was done in two sessions. Repeated courses of albendazole were given concurrently. Magnetic resonance imaging follow-up studies showed marked shrinkage of the irradiated cystic structures and initially increased perifocal edema. At a follow-up visit 3 years after gamma knife radiosurgery, the polycystic lesion, the perifocal edema, and the neurological symptoms had all markedly decreased. The patient is now stable and has minimal neurological symptoms, and the quality of her life has improved. Gamma knife radiosurgery may be an alternative for patients with cerebral alveolar hydatid disease for whom surgery is not possible.

The two human organic cation transporter genes SLC22A1 and SLC22A2 are located on chromosome 6q26

Polyspecific transporters for organic cations (OCT) belong to a new protein family which also include organic anion transporters. The first human transporters from this family (OCT1, OCT2) have been recently cloned. They translocate small cations like tetraethylammonium, choline and monoamine neurotransmitters and are involved in hepatic and renal cation excretion, respectively. We have localized the OCT1 and OCT2 genes (SLC22A1, SLC22A2) on chromosome 6q26.

[Liver changes in AIDS. Retrospective analysis of 227 autopsies of HIV-positive patients]

In a retrospective study of a 12-year period (1981-1992) liver histology was analyzed in 227 autopsied patients infected with the human immunodeficiency virus. Normal histology could only be documented in 29 patients (13%). In the majority of cases (56%) uncharacteristic changes were seen such as steatosis (34%), hemosiderosis (10%) or non-specific reactive hepatitis (7%). The finding of hepatic peliosis obtained in 4 patients was not associated with inflammatory liver changes, especially infections from Rochalimaea. Within a wide range of opportunistic infections recorded in 50 patients (22%), hepatitis caused by Cytomegalovirus (8%), Toxoplasma gondii (5%), Leishmania donovani (1%), Cryptococcus neoformans and Pneumocystis carinii (each 0.5%) was diagnosed. Among 16 cases (7%) of mycobacterial liver infections typical mycobacteria were found in two patients and atypical mycobacteria in 14 patients, respectively. In 23 patients (10%) chronic viral hepatitis, caused by HBV (7%) or HCV infections (3%), respectively, was observed. Hepatitis was typed as mild only in each 5 patients with HBV or HCV infection, whereas the remaining cases showed a transition towards cirrhosis. Two patients with HBV-associated cirrhosis developed hepatocellular carcinoma. The remaining 32 malignant liver tumors represented secondary neoplasms, including 13 cases of non-Hodgkin's lymphomas.

Terminal deletion of the long arm of chromosome 10: a new case with breakpoint in q25.3

Since the first patient with partial deletion of the long arm of chromosome 10 was described in 1978, another 23 cases have been reported, with the breakpoint ranging from 10q23.3-26.2. To contribute further to the delineation of the monosomy 10qter syndrome, we describe a female child who, at age 3 6/12 years, was diagnosed with a de novo deletion of the long arm of chromosome 10, with a breakpoint in 10q25.3. The phenotypic manifestations in this child are compatible with those of previously reported cases. However, in contrast to most other patients, we found a moderate expression of the syndrome, with no genitourinary or cardiac malformations and with only mild retardation. Based on our observations and those of others, we conclude that a typical craniofacial appearance and varying degrees of psychomotor retardation are always found in patients with 10q- syndrome.

The genomic structure of the chicken ICSBP gene and its transcriptional regulation by chicken interferon

The chicken interferon consensus sequence binding protein (ChICSBP) gene spans over 9 kb of DNA and consists, as its murine homolog, of nine exons. The first untranslated exon was identified by 5'-RACE technology. The second exon contains the translation initiation codon. Canonical consensus splice sites are found on every exon/intron junction. The introns are generally smaller than their mammalian counterparts. The ChICSBP and ChIRF-1 genes have been mapped by fluorescence in situ hybridization to different microchromosomes. The transcription start site has been mapped by primer extension. Inspection of the DNA sequence of a genomic clone containing the first exon and the region 1700-bp upstream revealed several potential cisregulatory elements of transcription. The ChICSBP mRNA is induced by recombinant ChIFN type I and ChIFN-gamma. A palindromic IFN regulatory element (pIRE) with high sequence homology to gamma activation site (GAS) sequences was functionally required in transient transfection assays for the induction of transcription by ChIFN-gamma.

Localization of the human membrane-type 2 matrix metalloproteinase gene (MMP15) to 16q12.1 near DNA elements that are part of centromeric and non-centromeric heterochromatin of 11 human chromosomes

We have localized a second gene for membrane-type matrix metalloproteinases, MT2-MMP, to chromosome 16q12 by in situ hybridization. FISH experiments using a genomic PAC clone containing the MT2-MMP gene resulted in an unusual hybridization pattern detecting centromeric and non-centromeric heterochromatin regions or its flanking sequences in 11 human chromosomes in addition to the MT2-MMP locus on chromosome 16q12. The detailed analysis of this hybridization pattern using molecular cytogenetic methods together with the specific hybridization of the MT2-MMP cDNA allowed a refined mapping of the gene to 16q12.1, directly adjacent to the 16q heterochromatin. Our findings may give some insights into the evolution of the MMP gene family.

In situ detection of a virulence factor mRNA and 16S rRNA in Listeria monocytogenes

Simultaneous in situ analysis of the structure and function of bacterial cells present within complex communities is a key for improving our understanding of microbial ecology. A protocol for the in situ identification of Listeria spp. using fluorescently tagged, rRNA-targeted oligonucleotide probes was developed. Ethanol fixation and enzymatic pretreatment with lysozyme and proteinase K were used to optimize whole cell hybridization of exponential phase and stationary phase Listeria spp. cells. In parallel, transcript probes carrying multiple digoxigenin molecules were combined with anti-digoxigenin Fab antibody fragments labeled with horseradish peroxidase to detect, via the catalytic deposition of fluorescein-tyramide, the iap-mRNA in single Listeria monocytogenes cells. The iap gene encodes the associated virulence factor p60. Application of the new signal amplification technique resulted in strong signals comparable in intensity to those obtained with fluorescently labeled rRNA-targeted oligonucleotide probes.