Dipeptidyl peptidase with strict substrate specificity of an anaerobic periodontopathogen Porphyromonas gingivalis

A dipeptidyl peptidase which hydrolyzed Xaa-Ala-p-nitroanilide was purified to homogeneity by sequential procedures including ammonium sulfate precipitation, ion-exchange chromatography, hydrophobic interaction chromatography, gel filtration and isoelectric focusing from the cell extract of Porphyromonas gingivalis. The purified enzyme hydrolyzed p-nitroanilide derivatives of Lys-Ala, Ala-Ala, and Val-Ala, but not Xaa-Pro. Enzyme activity was maximum at neutral pHs. Its molecular mass was 64 kDa with an isoelectric point of 5.7. The enzyme belonged to the family of serine peptidases.     

Cytology of basaloid squamous carcinoma of the bronchus. A case report

BACKGROUND: The cytologic appearance of basaloid squamous carcinoma (BSC) arising in the lower respiratory tract has not been described very well because of its rarity. This article describes a surgical case of bronchial BSC and provides the first documentation of the sputum and imprint cytologic features of the tumor. CASE: A 74-year-old man presented with hemoptysis. An abnormal intrabronchial mass was revealed by computed tomography and bronchoscopy. Preoperative cytology and biopsy showed that the mass was composed of small, round, atypical cells, but correct diagnosis was difficult. Under a tentative diagnosis of small round cell carcinoma, a right lobectomy was performed. The resected tumor was composed of small cells showing peripheral palisading and partial epidermoid differentiation. There was no glandular differentiation. Focal necrosis was also noted. Immunohistochemical markers for smooth muscle and neuroendocrine cells were negative. The tumor was eventually diagnosed as BSC or basaloid carcinoma (BC) with squamous differentiation. CONCLUSION: It is important to recognize this disease, especially when undetermined small round cell carcinoma is noted in cytologic specimens, in order to properly assess prognosis. Cytologic detection of nuclear palisading of the neoplastic cells, one of the hallmarks of the disease, may be difficult, however, careful examination to reveal neoplastic cells showing squamous differentiation appears helpful for diagnosis.     

Regulation of proton-to-electron stoichiometry in photosynthetic electron transport: physiological function in photoprotection

The primary stable products of photosynthetic electron flow are NADPH and ATP. Stoichiometry of their production depends on the ratio of protons pumped across the thylakoid membrane to electrons passed through the electron transport pathway (H(+)/e(-) ratio). Flexible requirements of the ATP/NADPH ratio by various assimilatory reactions in chloroplasts must be fulfilled by the H(+)/e(-) ratio during the electron flow. In addition to the well-known role of Delta pH during ATP synthesis, Delta pH also functions as a trigger of the down-regulation of photosystem II (PSII) photochemistry. Excessive light energy is safely dissipated as heat by this regulatory process to suppress the generation of toxic reactive oxygen species. Thus, regulation of the H(+)/e(-) ratio may function in the photoprotection, as well as in the regulation of the ATP/NADPH production ratio. It has long been the consensus that the H(+)/e(-) ratio can be controlled by regulating the proton-transporting Q-cycle in the cytochrome b(6)f complex and by the cyclic electron flow around photosystem I (PSI). Despite the possible physiological importance and the long history of interest, the molecular identity of Q-cycle regulation and the cyclic electron flow around PSI have been remained unclear. The recent improvements in research tools, including the genetic approach using chlorophyll fluorescence imaging and establishment of the chloroplast transformation technique, are providing new insights into classical topics. In this review, we focus on regulation of the H(+)/e(-) ratio especially from the view of photosynthetic regulation.     

Susceptibility gene for non-obstructive azoospermia located near HLA-DR and -DQ loci in the HLA class II region

The technical developments and expanded indications for testicular sperm extraction (TESE) with intracytoplasmic sperm injection (ICSI) provide great advantages for patients with non-obstructive azoospermia. Such success, however, also means that genetic abnormalities in non-obstructive azoospermia can be transmitted to the next generation, demonstrating the importance of being able to understand the genetic background of non-obstructive azoospermia. We have previously reported that human leukocyte antigens (HLA)-A33 and -B44 in the HLA class I region and the HLA-DRB1*1302 allele in the HLA class II region are linked to susceptibility to non-obstructive azoospermia in Japanese men. However, strong linkage of HLA-DRB1*1302 with HLA-A33 and -B44 is also evident in the Japanese population. Thus, uncertainty prevails as to whether the HLA class I or class II molecule is more directly associated with non-obstructive azoospermia. In the present study, we performed association analysis with 21 polymorphic microsatellite markers identified near the HLA genes to map the gene involved in the development of non-obstructive azoospermia more precisely. Microsatellite markers located in the HLA class I region or the class III region showed no statistically significant association with this disorder, although once again the HLA-A33 and -B44 alleles showed a significant association. In contrast, some of the microsatellite markers in the HLA class II region and at the HLA-DRB1 and -DQB1 loci displayed strong associations with non-obstructive azoospermia. Taken together, our previous and present data suggest that the critical region for development of non-obstructive azoospermia is near the HLA-DRB1 and -DQB1 segments in the HLA class II region.     

Cloning and sequencing of an endoglucanase gene from Scopulariopsis brevicaulis TOF-1212, and its expression in Saccharomyces cerevisiae

The egI gene, encoding a major endoglucanase (EGI) of Scopulariopsis brevicaulis TOF-1212, was cloned and sequenced. The eglgene consisted of 868 bp with one intron and encoded a protein of 229 amino acids with a calculated molecular mass of 22,392 daltons. The EGI was assigned to a family 45 of glycosyl hydrolases and showed high similarity with other fungal endoglucanases, especially with those of Humicola grisea and Fusarium oxysporum, on the basis of hydrophobic cluster analysis. The egI gene was expressed under the promoter of the phosphoglycerate kinase gene (PGK) in Saccharomyces cerevisiae. The transformed cells were able to secrete the enzyme efficiently in an active form.     

Apoptosis induced by chelation of intracellular zinc is associated with depletion of cellular reduced glutathione level in rat hepatocytes

Zn(2+) has multiple implications in cellular metabolism, including free radicals metabolism and cell death by apoptosis. In the present study, we examined the role of Zn(2+) in the regulation of apoptosis in cultured rat hepatocytes. The chelation of Zn(2+) by a membrane permeable metal ion chelator, N, N, N', N'-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN), induced apoptosis. Addition of ZnSO(4) prevented TPEN-induced apoptosis. Unlike the effect of TPEN, a membrane impermeable metal ion chelator, diethylenetriamine pentaacetic acid (DTPA), did not induce apoptosis, indicating that chelation of intracellular Zn(2+) was required to trigger apoptosis. Caspase-3-like proteolytic activity, a general biochemical mediator of apoptosis in a variety of cells and tissues, was also activated with the treatment of TPEN but not DTPA. TPEN treatment, but not DTPA, also resulted in the depletion of intracellular reduced glutathione (GSH) but addition of Zn(2+) recovered the GSH level. N-acetyl-L-cysteine (NAC), a thiol antioxidant, prevented TPEN-induced apoptosis. These results taken together suggest that intracellular Zn(2+) interfere with the apoptosis process, possibly through the regulation of cellular redox potential involving GSH.     

Anthocyanins in callus induced from purple storage root of Ipomoea batatas L

Two anthocyanins were isolated from the highly pigmented callus derived from the storage root of purple sweet potato (Ipomoea batatas L.) cultivar 'Ayamurasaki'. One was identified as cyanidin 3-O-sophoroside-5-O-glucoside, and the other as cyanidin 3-O-(2-O-(6-O-(E)-p-coumaroyl-beta-D-glucopyranosyl)-beta-D-glucop yranoside)-5-O-beta-D-glucopyranoside, by chemical and spectroscopic analysis.