Amino acid residues conferring the nucleotide binding properties of N-acetyl-D-glucosamine 2-epimerase (renin binding protein)

Our recent studies have demonstrated that the middle domain of N-acetyl-D-glucosamine (GlcNAc) 2-epimerase participates in the specificity for and binding of nucleotides. To identify the residue conferring nucleotide binding, amino acid substitutions were introduced in the human and rat GlcNAc 2-epimerases. The mutational analyses indicate that residue 171 of GlcNAc 2-epimerase is critical for the nucleotide binding of GlcNAc 2-epimerase.     

Block of sodium channels by tyramine and its analogue (N-feruloyl tyramine) in frog ventricular myocytes.

Pharmacological effects of tyramine and its analogue, N-feruloyl tyramine (NFT), on sodium and calcium currents in frog ventricular myocytes were examined using the whole-cell voltage-clamp technique. To improve the temporal and spatial control of the membrane potential, sodium currents (INa) were recorded in 45.5 mM [Na+]o at 10 degrees C. Both tyramine and NFT (1-100 microM) induced a concentration-dependent decrease in INa evoked from a holding potential of -80 mV without affecting a change in either the time to peak or the time constant for the falling phase of INa. Similarly the reversal potential for INa remained unchanged at a value close to that predicted from the Nernst equation. The finding that both tyramine and NFT decreased INa when activated maximally, from a holding potential of -120 mV, indicates that the amplitude of INa can be reduced independently of a change in the kinetics of the current. In addition, tyramine (100 microM) shifted the membrane potential for half maximal inactivation (Vh) of the steady-state inactivation (h infinity)-curve from -74 to -84 mV without affecting its slope. In contrast, NFT failed to affect the h infinity-curve. The calcium current (ICa) recorded in the presence of 0.3 microM TTX was not affected by either 100 microM tyramine or NFT. We concluded that tyramine directly blocks Na channel by shifting h infinity-curve and by suppressing maximum Na channel conductance, while NFT suppresses only maximum Na channel conductance.     

Expression and function of X chromosome-linked inhibitor of apoptosis protein in Sjögren's syndrome

Apoptotic cell death in acinar and ductal epithelial cells is thought to play an important role in the development of salivary gland dysfunction in patients with Sjogren's syndrome (SS). We examined the expression of anti-apoptotic molecules in salivary glands from patients with SS. The labial salivary glands from six human T-cell leukemia virus (HTLV)-I-seronegative and eleven HTLV-I-seropositive SS patients were analyzed by immunohistochemistry. In vitro experiments were performed with a human salivary gland cell line (HSG cells). Immunohistologic analyses revealed that Bcl-2 and Bcl-x were preferentially expressed in salivary infiltrating mononuclear cells more than acinar and ductal epithelial cells. In contrast, strong X chromosome-linked inhibitor of apoptosis protein (XIAP) expression was evident in both acinar and ductal epithelial cells. The pattern of expression of these anti-apoptotic molecules was similar in both HTLV-I-seropositive and HTLV-I -seronegative SS patients. Western blot analysis confirmed expression of XIAP in cultured HSG cells. The expression of XIAP in HSG cells was increased by IL-1beta, TGF-beta1, or IL-10. However, XIAP expression was down-regulated by TNF-alpha, which induced apoptotic cell death of HSG cells with an increase in caspase-3 activity. These effects of TNF-alpha in HSG cells were antagonized by IL-1beta, TGF-beta1, or IL-10. Our results suggest that XIAP is important in regulating apoptotic cell death of acinar and ductal epithelial cells in patients with SS.     

Bronchial granular cell tumor with osteopontin and osteonectin expression: a case report

The case of a 52-year-old Japanese man with bronchial granular cell tumors with osteopontin and osteonectin expression is reported here because there have been few investigations of their expression in benign tumors. He was admitted because of sudden hematemesis. A bronchoscopic examination revealed a lobulated polypoid tumor located in the left and right bronchi. Histologically, most tumor cells had abundant granular eosinophilic cytoplasm and were immunoreactive for S-100, neuron-specific enolase (NSE), CD68 and vimentin. Moreover, osteopontin-positive tumor cells were randomly distributed in the tumor tissue, but few stromal cells were positive. In contrast, osteonectin was mainly expressed in the peripheral tumor cells and was also distributed in the stromal cells. Blood vessels at the tumor border in which osteonectin-positive tumor cells were distributed, proliferated moderately. These results suggest that osteopontin and osteonectin may play a role in the progression of granular cell tumors and in the interaction between the tumor and host or angiogenesis around the tumor, respectively.     

BRONCHIAL PLASMACYTOMA IDENTIFIED BY IMMUNOPEROXIDASE TECHNIQUE ON PARAFFIN EMBEDDED SECTION

A case of bronchial plasmacytoma occurring in a 57- year-old housewife is reported. She had had the productive cough and the "abnormal shadow" in the right lower lobe for three years before admission. On bronchocopy, a tumor was found in the right main bronchus, large enough to obstruct the air way. The tumor was resected through rigid bronchoscope. Histological impression was "plasmacytoma with local amyloid deposit." M-protein was never detected in the serum or urine. Applying the immunoperoxidase technique for the paraffin section, the plasma cells were found to contain only a single type of immunoglobulin, Ig G-L. The differential diagnosis between plasmacytoma and plasma cell granuloma was made, and plasmacytoma was considered to be one type of extranodal malignant lymphoma.     

Association between thyroid cancer of cribriform variant and familial adenomatous polyposis.

A case of a 20 year old Japanese woman who developed thyroid cancer exhibiting unusual cribriform structures while being followed up for familial adenomatous polyposis/Gardner's syndrome is reported. The patient presented with osteomas, pigmented retinal lesions, and adenomas of the duodenum and the papilla of Vater, in addition to numerous adenomatous polyps in the colorectum. On ultrasonography, the thyroid cancer was localised to the right lobe and was identified as an irregular, internal echo tumour with a peripheral hypoechoic zone, measuring 1.8 cm in diameter. Histological examination of the resected tumour showed a concomitance of papillary proliferation and cribriform structures with follicles of varying sizes. These features can be distinguished from sporadic thyroid cancer.     

Relationship between core temperature and skin blood flux in lower limbs during prolonged arm exercise in persons with spinal cord injury

The purposes of the present study were to examine the response of the skin blood flux (SBF) in the paralyzed lower limbs of persons with spinal cord injury (PSCI) and to clarify the relationship between the SBF and core temperature during prolonged arm exercise. Eight male PSCI with lesions from T6 to L5 and six male control subjects (CS) participated in this study. The subjects rested for 60 min and then performed arm-cranking exercise at 20 W for 30 min at 25 °C. The tympanic membrane temperature (T _ty) and SBF in the anterior thigh (SBFT) and in the posterior calf (SBFC) were continuously measured throughout the experiment. The SBFC did not change in either PSCI or CS during the experiment. The SBFT in four PSCI with high lesions (T6 to T12), remained unchanged during exercise. The SBFT in the other four PSCI with low lesions (T12 to L5, SBFT+) began to elevate markedly when the T t, exceeded a threshold temperature of 36.69 °C. The pattern of increase of SBFT in SBFT+ was similar to that in CS, although onset of the increase in SBFT was delayed and the peak of SBFT during exercise was significantly lower in comparison with the CS. We consider that these differences between the SBFT+ and CS were largely attributable to the lowerT _ty in the former group, which took a prolonged time to reach the threshold of 36.69 °C.     

Stereological analysis of Reinke's crystals in human Leydig cells

Summary Reinke's crystals in human Leydig cells were analyzed stereologically to assess their functional role. Testicular tissues were taken from seven older men (57–82 years old) with prostatic carcinoma and also from seven younger men (26–38 y.o.) complaining of male infertility. Sections 0.5 m thick, stained with toluidine blue or Heidenhein's iron-hematoxylin were examined by a point-counting method and with a Particle Measurement Computor System (MC). When the patients were grouped by age, the mean crystal volume, the number of crystals per cell, the volume of crystals per cell and the volume ratio of crystals to cell were significantly larger in the older age group than in the younger age group. In particular, the latter three variables correlated well with the age of subjects, with correlation coefficients of r=0.66–0.85. On the other hand, none of these variables had any correlation with the concentration of plasma testosterone. These results indicate that Reinke's crystals can be considered as degenerative products in cell life but not as facultative constituents for testosterone production.Supported in part by a grant from Medical Foundation of Ehime, Japan     

Bacterial superantigen-treated intestinal epithelial cells upregulate heat shock proteins 25 and 72 and are resistant to oxidant cytotoxicity

While the pathological events evoked by infection are commonly described, effective host responses to bacteria and their products should primarily be protective. Heat shock protein (Hsp) expression is upregulated by many stimuli and serves to maintain intracellular protein integrity. The ability of the prototypic superantigen, Staphylococcus aureus enterotoxin B (SEB) to induce Hsps was investigated with BALB/c mice and by in vitro addition to the murine small intestinal epithelial cell line MSIE. SEB-treated (5 or 100 microg intraperitoneally) mice revealed increased Hsp25 and Hsp72, but not Hsc73, in jejunal lymphocytes and epithelial cells. A similar Hsp response to SEB occurred in MSIE cells and was preceded by activation of the ERK1/2 and p38 mitogen-activated protein kinases but not the SAPK/JNK pathway; pharmacological inhibition of ERK1/2, but not p38, significantly reduced SEB-induced Hsps. Moreover, SEB-treated MSIE cells were protected against oxidant-induced cytotoxicity (measured by 51Cr release) and F-actin depolymerization. Thus, SEB exposure results in a rapid induction of the Hsp25 and Hsp72 in intestinal epithelial cells, both directly and through lymphocyte activation, and we suggest that this event is important in protecting the gut from damage by Staphylococcus infection or in the reparatory process and may be a generalized response to lumen-derived bacterial toxins.