The psbA-gene from a red alga resembles those from Cyanobacteria and Cyanelles

Summary Plastid DNA (ptDNA) from the unicellular red alga Cyanidium caldarium was isolated. A 5.8 kb Eco RI, fragment containing the entire psbA-gene was cloned and the nucleotide sequence of the psbA-gene determined. At the carboxyl terminus the encoded protein (D1) contains the seven amino acid-insertion which was found to be typical of the cyanobacteria and the cyanelles of Cyanophora paradoxa. However, the overall sequence homology does not support a direct relationship between the plastids of Cyanidium, cyanelles and the cyanobacteria. As in other photosynthetic organisms the psbA-gene is transcribed as a monocistronic mRNA. The ribosomal RNA operon was located 4 kb upstream of the psbA-gene.     

Neither lymphotoxin alpha nor lymphotoxin beta receptor expression is required for biogenesis of lymphoid aggregates or differentiation of natural killer cells in the pregnant mouse uterus

Gene ablation studies in mice indicate that lymphotoxin (LT)alpha, LTbeta and LTbetaR are essential for the genesis of lymph nodes (LN), normal structural development of peripheral lymphoid tissues and the differentiation of natural killer (NK) cells. LTbetaR binds to the heterotrimeric cytokines LTalpha1beta2 and LIGHT. LTs also regulate stromal cell expression of lymphocyte homing chemokines. Uterine decidualization in normal (+/+) mice is accompanied by the appearance and maturation of large numbers of uterine NK (uNK) cells that differentiate from precursors mobilized to the uterus from secondary lymphoid tissues. uNK cells accumulate in a transient, lymphocyte-rich region known as the metrial gland or, more recently, the mesometrial lymphoid aggregrate of pregnancy (MLAp). To determine if LTs contribute to development of the MLAp, and to the differentiation and/or localization of uNK cells, a histological study was undertaken of implantation sites from LTalpha null, LTbetaR null and gestation day-matched, normal mice. Implantation sites from the gene-ablated mice contained abundant numbers of uNK cells that localized appropriately. This indicates that the stromally derived molecules supporting NK cell differentiation in the uterus differ from those used in secondary lymphoid organs.     

The developmentally regulated neural crest-associated glycotope HNK-1 predicts metastasis in cutaneous malignant melanoma

Aberrant glycosylation is a common feature of metastatic sub-clones of malignant tumours and in uveal melanoma in particular, the HNK-1 glycotope has been positively correlated with poor prognosis. So far, no such correlation has been investigated in cutaneous melanoma. In order to do so, HNK-1 expression was evaluated immunohistochemically in 100 primary cutaneous melanomas and correlated with metastasis after up to 10-years' follow-up. Furthermore, HNK-1 expression was analysed in metastatic deposits (19 distant cutaneous metastases and six sentinel lymph node metastases), as well as in benign nevi. Kaplan-Meier analysis revealed a positive association between HNK-1 expression and metastasis (p < 0.005) and multivariate Cox regression analysis adjusted for the standard prognostic markers ulceration and vertical tumour thickness confirmed HNK-1 expression as an independent prognostic marker. HNK-1 expression was preserved in 42% of the distant cutaneous metastases, but metastatic cells in lymph nodes were devoid of HNK-1 immunoreactivity. None of the benign pigmented lesions exhibited HNK-1 immunoreactivity. Expression of the HNK-1 glycotope in cutaneous malignant melanoma is an independent prognostic marker of metastasis. Differential HNK-1 expression at the metastatic sites implies that its expression is modulated by the surrounding environment. As HNK-1 is also transiently expressed during migration of melanocyte precursor cells derived from the neural crest, recapitulation of this transient expression might occur during metastatic spread of cutaneous malignant melanoma.     

Up-regulation of cathepsin X in Helicobacter pylori gastritis and gastric cancer

Recently, we identified increased cathepsin X expression in H. pylori-infected gastric mucosa. Here, we describe further up-regulation in gastric cancer and report on the role of inflammatory cytokines required for cathepsin X up-regulation in H. pylori-infected gastric mucosa, as well as on consequences for cellular invasion. Biopsy specimens were taken from the antrum, corpus and cardia of H. pylori-infected and non-infected patients. Gastric cancer samples were obtained from patients undergoing gastric surgery. Cathepsin X was detected in gastric mucosa by quantitative real-time RT-PCR, western blotting and immunohistochemistry. Induction of cathepsin X expression in epithelial and inflammatory cells caused by H. pylori infection was tested in in vitro contact and non-contact co-cultures of AGS cells and monocytic cells. Patients with H. pylori gastritis showed significantly higher cathepsin X mRNA (2.5-fold) and protein (1.6-fold) expression than H. pylori-negative patients. Cathepsin X was also up-regulated in gastric cancer (3-12-fold) compared to non-neoplastic mucosa. Cathepsin X was predominantly expressed by macrophages in the mucosal stroma and in glands of the antral mucosa. In addition, tumour cells stained for cathepsin X in 26 (68%) patients with gastric carcinoma. In general, staining was significantly more common (20 vs. 6 patients) and more intense (3.55 vs. 0.83) in intestinal type gastric cancer than in the diffuse type. In vitro cell culture experiments revealed that intercellular signalling between pathogenicity island (PAI)-positive H. pylori-infected epithelial cells and macrophages via soluble factors in the culture medium seems to be responsible for increased expression of cathepsin X in monocytes. Using antisense oligonucleotides, cathepsin X up-regulation was directly associated with higher invasiveness in vitro. Although no correlation of cathepsin X expression and TNM stage was found, our study demonstrates that cathepsin X plays a role not only in the chronic inflammation of gastric mucosa but also in the tumourigenesis of gastric cancer.     

Vibrio-associated gastroenteritis in the lower Cross-River Basin of Nigeria.

A total of 120 Vibrio species were isolated from 588 patients with acute diarrheal disease during an outbreak of gastrointestinal tract infections at different locations in the lower Cross River Basin of Nigeria. Vibrio cholerae O1, biotype El Tor, serotype Ogawa, was the prominent organism isolated from the Vibrio-associated diarrheal cases. During the 3 months of study, V. cholerae non-O1 was recovered from 10 patients while Vibrio parahaemolyticus was recovered from 19 patients. The significance of this study is the recognition that there is an ecological niche which supports V. cholerae non-O1 and V. parahaemolyticus in the Cross River Basin of Nigeria.     

Lymphoblastic crisis of chronic myelogenous leukemia. Hand mirror variant

We present, to our knowledge, the first extensively studied case of lymphoid L2 blast crisis of chronic myelogenous leukemia with a hand mirror cell (HMC) variant. Special stains revealed the leukemic cells to be terminal deoxynucleotidyl transferase positive by immunofluorescence and cytochemically positive for alpha-naphthyl acetate esterase and acid phosphatase (diffuse granular). Immunophenotyping identified the major leukemic cell population as B-cells that expressed CD10+, CD19+, and HLA-DR+. It was not possible to separate the HMC and the non-HMC leukemic population by gating various cell populations, dual staining, cytochemistry, or by terminal deoxynucleotidyl transferase. Gene rearrangements were observed in both Ig heavy-chain alleles and one T-cell antigen receptor gamma-subunit allele. The rearrangements occupied all of the cells, indicating that the HMC and non-HMC were of a common clonal origin. The patient had a mosaic karyotype, with 90% of the cells having t(9;22), t(8;14), and t(9;15) translocations, an additional chromosome 8, and deleted chromosomes 9 and 15. Antibodies to simian sarcoma-associated virus and baboon endogenous virus were isolated in the patient's peripheral blood plasma.     

Emergence of rifampicin resistance in methicillin-resistant Staphylococcus aureus isolated at a Turkish university hospital

Twenty-three rifampicin-resistant methicillin-resistant Staphylococcus aureus (MRSA) isolated in three wards at a university hospital in Turkey between June, 2000, and February, 2001, were studied for their genetic relatedness using a combination of antibiogram, coagulase serotyping, coagulase gene polymorphism (coa-RFLP), and pulsed-field gel electrophoresis (PFGE). They all expressed high-level rifampicin resistance (MIC, >256 mg/L) and were resistant to gentamicin, kanamycin, amikacin, ciprofloxacin, tetracycline, and cadmium acetate and were susceptible to fusidic acid, vancomycin, trimethoprim, and mupirocin. They belonged to the same coagulase serotype (serotype IV) and had identical coa-RFLP patterns. In contrast, PFGE generated nine banding patterns designated type A, types A1-A5, B, C, and D. The most common PFGE pattern (type A) and its subtypes (types A1-A5) were seen in 20 (87%) of the 23 isolates in the three wards. The results demonstrated the acquisition of rifampicin resistance by different MRSA clones and the spread of one clone among patients in the three wards.     

Akute Schäden des proximalen Tubulusepithels der Rattenniere nach einer einmaligen hochdosierten Furosemid-Gabe

Zusammenfassung Eine einmalige intraperitoneale Furosemid-Gabe von 50–200 mg/kg KG führt in der Rattenniere zu Epithelschäden im Bereich der pars recta des proximalen Tubulus. Diese tubulären Veränderungen treten nicht auf, wenn der Furosemid-induzierte Wasser- und Elektrolytverlust durch einen experimentell angelegten vesico-venösen Shunt verhindert wird. Die Tubuluszellschäden werden als Folge einer intracellulären Furosemid-Anreicherung bei vermindertem intratubulären Harnstrom angesehen.Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Activity-inducible protein Homer1a/Vesl-1S promotes redistribution of postsynaptic protein Homer1c/Vesl-1L in cultured rat hippocampal neurons

In cultured rat hippocampal neurons, overexpression of Homer1a/Vesl-1S, an inducible protein upregulated by seizure or long-term potentiation, caused a reduction of punctate distribution of a postsynaptic protein Homer1c/Vesl-1L, without significant decrease in its total amount. Clusters of F-actin were also decreased. Treatments of cells with BDNF or a proteasome inhibitor, which cause increase in the expression level of endogenous Homer1a, also resulted in the reduction of Homer1c puncta. These results indicate that the accumulation of Homer1a, either exogenously expressed or endogenously induced, caused redistribution and dispersion of postsynaptic clusters of Homer1c and F-actin, suggesting an important role of Homer1a in synaptic remodeling.     

Presynaptic short-term depression is maintained during regulation of transmitter release at a GABAergic synapse in rat hippocampus

To examine possible interactions between fast depression and modulation of inhibitory synaptic transmission in the hippocampus, we recorded from pairs of synaptically connected basket cells (BCs) and granule cells (GCs) in the dentate gyrus of rat brain slices at 34 °C. Multiple-pulse depression (MPD) was examined in trains of 5 or 10 inhibitory postsynaptic currents (IPSCs) evoked at frequencies of 10–00 Hz under several conditions that inhibit transmitter release: block of voltage-dependent Ca²⁺ channels by Cd²⁺ (10 μ m ), activation of γ-amino-butyric acid type B receptors (GABA_BRs) by baclofen (10 μ m ) and activation of muscarinic acetylcholine receptors (mAchRs) by carbachol (2 μ m ). All manipulations led to a substantial inhibition of synaptic transmission, reducing the amplitude of the first IPSC in the train (IPSC₁) by 72 %, 61 % and 29 %, respectively. However, MPD was largely preserved under these conditions (0.34 in control versus 0.31, 0.50 and 0.47 in the respective conditions at 50 Hz). Similarly, a theta burst stimulation (TBS) protocol reduced IPSC₁ by 54 %, but left MPD unchanged (0.40 in control and 0.39 during TBS). Analysis of both fractions of transmission failures and coefficients of variation (CV) of IPSC peak amplitudes suggested that MPD had a presynaptic expression site, independent of release probability. In conclusion, different types of presynaptic modulation of inhibitory synaptic transmission converge on a reduction of synaptic strength, while short-term dynamics are largely unchanged.