Urea transporter expression in aging kidney and brain during dehydration

Aging is commonly associated with defective urine-concentrating ability. The present study examined how the kidney and the brain of senescent (30-mo-old) female WAG/Rij rats respond to dehydration induced by 2 days of water deprivation in terms of urea transporter (UT) regulation. In euhydrated situation, senescent rats exhibited similar vasopressin plasma level but lower urine osmolality and papillary urea concentration and markedly reduced kidney UT-A1, UT-A3, and UT-B1 abundances compared with adult (10-mo-old) rats. Senescent rats responded to dehydration similarly to adult rats by a sixfold increase in vasopressin plasma level. Their papillary urea concentration was doubled, without, however, attaining that of dehydrated adult rats. Such an enhanced papillary urea sequestration occurred with a great fall of both UT-A1 and UT-A3 abundances in the tip of inner medulla and an increased UT-A1 abundance in the base of inner medulla. UT-A2 and UT-B1 were unchanged. These data suggest that the inability of control and thirsted senescent rats to concentrate urine as much as their younger counterparts derives from lower papillary urea concentration. In aging brain, UT-B1 abundance was increased twofold together with a fourfold increase in aquaporin-4 abundance. Dehydration did not alter the abundance of these transporters.     

Unusual metastasis of papillary thyroid carcinoma to larynx and hypopharynx a case report

Background  

Although direct infiltration of papillary carcinoma of thyroid to larynx, trachea and esophagus is well recognized, lymphatic and vascular metastases to larynx and hypopharynx have rarely been reported.     

Changes in rat liver mitochondria with aging. Lon protease-like reactivity and N(epsilon)-carboxymethyllysine accumulation in the matrix.

Aging is accompanied by a gradual deterioration of cell functions. Mitochondrial dysfunction and accumulation of protein damage have been proposed to contribute to this process. The present study was carried out to examine the effects of aging in mitochondrial matrix isolated from rat liver. The activity of Lon protease, an enzyme implicated in the degradation of abnormal matrix proteins, was measured and the accumulation of oxidation and glycoxidation (Nepsilon-carboxymethyllysine, CML) products was monitored using immunochemical assays. The function of isolated mitochondria was assessed by measuring respiratory chain activity. Mitochondria from aged (27 months) rats exhibited the same rate of oxygen consumption as those from adult (10 months) rats without any change in coupling efficiency. At the same time, the ATP-stimulated Lon protease activity, measured as fluorescent peptides released, markedly decreased from 10-month-old rats (1.15 +/- 0.15 FU x micro g protein-1 x h-1) to 27-month-old-rats (0.59 +/- 0.08 FU x micro g protein-1 x h-1). In parallel with this decrease in activity, oxidized proteins accumulated in the matrix upon aging while the CML-modified protein content assessed by ELISA significantly increased by 52% from 10 months (11.71 +/- 0.61 pmol CML x micro g protein-1) to 27 months (17.81 +/- 1.83 pmol CML x micro g protein-1). These results indicate that the accumulation of deleterious oxidized and carboxymethylated proteins in the matrix concomitant with loss of the Lon protease activity may affect the ability of aging mitochondria to respond to additional stress.     

Steady-state kinetic analysis of human ubiquitin-activating enzyme (E1) using a fluorescently labeled ubiquitin substrate

We report the synthesis of fluorescently labeled ubiquitin (Ub) and its use for following ubiquitin transfer to various proteins. Using Oregon green (Og) succinimidyl ester, we prepared a population of Ub mainly labeled by a single Og molecule; greater than 95% of the Og label is associated with Lys 6 of Ub. We demonstrate that Og-Ub is efficiently accepted by Ub-utilizing enzymes, such as the human ubiquitin-activating enzyme (E1). We used this fluorescent substrate to follow the steady-state kinetics of human E1-catalyzed Ub-transfer to the ubiquitin-carrier enzyme Ubc4. In this reaction, E1 uses three substrates: ATP, Ubc4, and Ub. The steady-state kinetics of Og-Ub utilization by E1 is presented. We have also used analytical ultracentrifugation methods to establish that E1 is monomeric under our assay condition (low salt) as well as under physiological condition (150 mM NaCl).     

Peptides that mimic Candida albicans-derived beta-1,2-linked mannosides

Beta-1,2-linked mannosides from Candida albicans phosphopeptidomannan (PPM) bind to macrophages through a receptor independent from the macrophage alpha-linked mannose receptor and stimulate these cells to secrete immune mediators. Anti-beta-1,2-linked mannoside but not anti-alpha-linked mannoside antibodies produced after immunization with neoglycoproteins protect animals from disseminated candidiasis. In this study, peptides that mimic beta-1,2-linked mannosides were isolated using phage display methodology. A phage library expressing random peptides was panned with an anti-beta-1,2-linked mannoside monoclonal antibody (mAb). After three rounds of biopanning, the isolated phages were able to inhibit recognition of C. albicans by the mAb. Sixty percent of the phages had an identical DNA insert corresponding to the peptide sequence FHENWPS that was recognized specifically by the mAb. Injection of KLH-coupled peptide into mice generated high titers of polyclonal antibodies against C. albicans yeast cell walls. The anti-FHENWPS antibodies bound to C. albicans PPM and were inhibited by soluble beta-1,2-mannotetraose. Together, these data provide evidence for mimotopic activity of the peptide selected by biopanning with the anti-beta-1,2-oligomannoside mAb.     

Bat Airway Epithelial Cells: A Novel Tool for the Study of Zoonotic Viruses

Bats have been increasingly recognized as reservoir of important zoonotic viruses. However, until now many attempts to isolate bat-borne viruses in cell culture have been unsuccessful. Further, experimental studies on reservoir host species have been limited by the difficulty of rearing these species. The epithelium of the respiratory tract plays a central role during airborne transmission, as it is the first tissue encountered by viral particles. Although several cell lines from bats were established recently, no well-characterized, selectively cultured airway epithelial cells were available so far. Here, primary cells and immortalized cell lines from bats of the two important suborders Yangochiroptera and Yinpterochiroptera, Carollia perspicillata (Seba''s short-tailed bat) and Eidolon helvum (Straw-colored fruit bat), were successfully cultured under standardized conditions from both fresh and frozen organ specimens by cell outgrowth of organ explants and by the use of serum-free primary cell culture medium. Cells were immortalized to generate permanent cell lines. Cells were characterized for their epithelial properties such as expression of cytokeratin and tight junctions proteins and permissiveness for viral infection with Rift-Valley fever virus and vesicular stomatitis virus Indiana. These cells can serve as suitable models for the study of bat-borne viruses and complement cell culture models for virus infection in human airway epithelial cells.     

Signal requirements for lymphocyte activation: Role of a T-cell growth factor produced by guinea pig peritoneal exudate lymphocytes

Peritoneal exudate lymphocytes (PEL) from immunized guinea pigs, when pulsed with antigen, rapidly release a T-cell stimulatory factor (TSF). TSF nonspecifically enhances the proliferation of purified guinea pig T cells in the presence of another signal such as PMA, PHA, or Con A. On a per cell basis, antigen-pulsed PEL produce about 14 times more activity than similarly stimulated lymph node lymphocytes.Several lines of evidence support the view that TSF is the guinea pig equivalent of TCGF (IL-2). TSF containing supernatants have IL-2 activity when assayed on the IL-2-dependent CT6 cell line. When TSF containing supernatants were absorbed with CT6 cells, there was a significant decrease of both TSF activity as assessed on guinea pig T cells as well as IL-2 activity as assessed by the CT6 assay. Additionally, partially purified human and mouse IL-2 have TSF activity, while the macrophage product, IL-1, has no TSF activity. After chromatography on a S-200 column, TSF activity and IL-2 activity coelute at an apparent molecular weight of 19,000.