Detection and regulation of Cu/Zn-SOD and Mn-SOD in rat cochlear tissues

Relative levels of copper/zinc-superoxide dismutase (Cu/Zn-SOD) and manganese-superoxide dismutase (Mn-SOD) in individual cochlear tissues were detected by the use of an enzyme-linked immunosorbent assay (ELISA). A heterogeneous distribution of Cu/Zn-SOD was observed in the individual tissues of control animals: high levels were measured in the stria vascularis (SV), intermediate levels of enzyme were measured in the spiral ligament (SL), and low levels were measured in the organ of Corti region (OC); collectively, these levels were not statistically significant (P = 0.0645). Levels of Mn-SOD in individual tissues of the control group were statistically significant (P < 0.05): high levels were measured in the SV, medium levels were detected in the SL, and low levels were identified in the OC. Following the administration of methylprednisolone (MP), a significant reduction of Cu/Zn-SOD in the SV (P < 0.05) and a non-significant, but noticeable, increase (> 30%) of Mn-SOD in the OC were observed. These results indicate that levels of SOD are tissue specific and that SOD is subject to glucorticoid regulation.

Genomic structure and regulation of Kcn1, a cGMP-gated potassium channel

We recently cloned a novel rabbit gene that encodes a 725-amino acid protein (Kcn1) (Y. Yao, A. S. Segal, P. Welling, X. Zhang, C. M. McNicholas, D. Engel, E. L. Boulpaep, and G. Desir. Proc. Natl. Acad. Sci. USA 92: 11711-11715, 1995). Kcn1 RNA injected in Xenopus oocytes leads to the expression of potassium channels that are specifically activated by guanosine 3',5'-cyclic monophosphate (cGMP). Northern blot and ribonuclease (RNase) protection analysis show that Kcn1 is differentially expressed in kidney, aorta, brain, and heart. The purpose of present study is to determine the structure of Kcn1 gene, analyze the promoter region, and identify cis-regulatory elements responsible for transcription. We find that the coding region of Kcn is intronless. The major transcription initiation site was identified by primer extension. Sequence analysis of the 5'-flanking region indicates that, although the gene lacks a typical TATA box, it does have a TATA-box-like region (-TAT-). Using luciferase reporter constructs transfected in the porcine kidney cell line (LLC-PK1), the promoter region and a 5' enhancer element were identified by deletion analysis. Phorbol esters (12-O-tetradecanoylphorbol-13-acetate) and forskolin stimulated Kcn1 gene expression 2.5- and 3.5-fold, respectively. In conclusion, we have identified the region of the novel potassium channel gene, Kcn1, that contains the promoter, a 5' enhancer, and several cis-regulatory elements and shown that gene transcription is stimulated by cAMP and phorbol esters.

Involvement of mouse Mlh1 in DNA mismatch repair and meiotic crossing over

Mice that are deficient in either the Pms2 or Msh2 DNA mismatch repair genes have microsatellite instability and a predisposition to tumours. Interestingly, Pms2-deficient males display sterility associated with abnormal chromosome pairing in meiosis. Here mice deficient in another mismatch repair gene, Mlh1, possess not only microsatellite instability but are also infertile (both males and females). Mlh1-deficient spermatocytes exhibit high levels of prematurely separated chromosomes and arrest in first division meiosis. We also show that Mlh1 appears to localize to sites of crossing over on meiotic chromosomes. Together these findings suggest that Mlh1 is involved in DNA mismatch repair and meiotic crossing over.

Molecular cloning of a glibenclamide-sensitive, voltage-gated potassium channel expressed in rabbit kidney

Shaker genes encode voltage-gated potassium channels (Kv). We have shown previously that genes from Shaker subfamilies Kv1.1, 1.2, 1.4 are expressed in rabbit kidney. Recent functional and molecular evidence indicate that the predominant potassium conductance of the kidney medullary cell line GRB-PAP1 is composed of Shaker-like potassium channels. We now report the molecular cloning and functional expression of a new Shaker-related voltage-gated potassium channel, rabKv1.3, that is expressed in rabbit brain and kidney medulla. The protein, predicted to be 513 amino acids long, is most closely related to the Kv1.3 family although it differs significantly from other members of that family at the amino terminus. In Xenopus oocytes, rabKv1.3 cRNA expresses a voltage activated K current with kinetic characteristics similar to other members of the Kv1.3 family. However, unlike previously described Shaker channels, it is sensitive to glibenclamide and its single channel conductance saturates. This is the first report of the functional expression of a voltage-gated K channel clone expressed in kidney. We conclude that rabKv1.3 is a novel member of the Shaker superfamily that may play an important role in renal potassium transport.

Localization of the mineralocorticoid receptor in rat cochlear tissue

Distribution of the mineralocorticoid receptor within rat cochlear tissue was studied by immunohistochemistry. Intense immunoreactions of mineralocorticoid receptor antibodies were observed in outer and inner hair cells of the organ of Corti, stria vascularis, spiral ligament and spiral ganglion cells. Moderate to weak immunostaining was observed in the spiral limbus and cochlear nerve. Results of this study suggest that cochlear tissue is a mineralocorticoid hormone target tissue.

Ginsenoside-Ia: a novel minor saponin from the leaves of Panax ginseng

A new saponin, named ginsenoside-I (a), was isolated from leaves of Panax Ginseng, together with nine known saponins, and its structure was elucidated as 3beta,6alpha,12beta,20(S)-tetrahydroxyldammar-24(25)-ene (20- O-beta-D-glucopyranosyl)-3-O-beta-D-glucopyranoside on the basis of chemical and 2D-NMR methods.

Biochemical characterization of ezrin-actin interaction

The highly related actin isoforms are thought to have different functions. We recently demonstrated a polarized distribution of actin isoforms in gastric parietal cells and association of gastric ezrin with the cytoplasmic beta-actin isoform (Yao, X., Chaponnier, C., Gabbiani, G., and Forte, J. G. (1995) Mol. Biol. Cell. 6, 541-557). Here we used ultrastructural immunocytochemistry to verify that beta-actin is located within canalicular microvilli and the apical cortex of parietal cells, similar to the localization reported for ezrin. Furthermore, we tested whether ezrin binds preferentially to cytoplasmic beta-actin compared with the skeletal muscle alpha-actin isoform. Purified cytoplasmic beta-actin (from erythrocytes) and skeletal alpha-actin were assembled with gastric ezrin. Co-sedimentation experiments showed that gastric ezrin selectively co-pelleted with the beta-actin isoform and only very poorly with alpha-actin. Binding of erythrocytic beta-actin to ezrin is saturable with a molar ratio of approximately 1:10 (ezrin:actin) and a dissociation constant approximately 4.6 x 10(-8) M. In addition, ezrin promoted pyrene-labeled actin assembly, with predominant effects on filament elongation and a distinct preference for beta-actin compared with alpha-actin. Given these isoform-selective associations, we speculate that actin isoforms might segregate into different functional domains and exert specificity by interacting with isoform-orientated binding proteins.

[A study on neural regeneration after experimental epikeratophakia]

OBJECTIVE

To assess the effect of epikeratophakia (EKP) on corneal nerve regeneration and the recovery of corneal sensitivity.

METHODS

36 adult rabbits underwent epikeratophakia with either 0.2 mm or 0.3-0.35 mm circular trephination. A histochemical technique (acetylcholine esterase staining) was used to investigate the process of corneal nerve regeneration, and the recovery of corneal sensitivity was determined in 36 rabbits at various intervals after EKP.

RESULTS

The corneal sensory nerves began to regenerate just peripheral to the host-donor interface 3 weeks following EKP, the nerve fibers traveled toward the stroma of the lenticules at 2 months, and formed a sparse subepithelial plexus at 8 months after surgery. A relative hyposthesia was found in the central zone of the lenticule when compared with its peripheral zone 4 months postoperatively. The sensitivity of the central zone remained lower at 5-8 months after EKP though it had remarkably increased. The density of re-innervated fibers was higher in the shallow incision than that in deeper one.

CONCLUSION

It is suggested that the factors affecting the corneal innervation and the recovery of corneal sensitivity following EKP include; (1) the scar formation as a barrier; (2) the adaptation to the micro-environment around the lenticule; and (3) the depth of trephine cut. Therefore, a 0.2-0.25 mm depth of trephine incision is advantageous to the lamellar dissection, graft suturation and corneal nerve regeneration.

Phenotyping of esterase D and acid phosphatase by rapid isoelectric focusing on PhastSystem

A rapid isoelectric focusing method on PhastSystem was applied to investigate the distribution of esterase D (ESD) and acid phosphatase (ACP) phenotypes in 152 and 112 unrelated healthy donors, respectively, from the Han population in Beijing. Laboratory-made gels with a pH range of 5.0-7.0 and 5.0-8.0 were used for analysis of ESD and ACP, respectively, with 1 microliter sample loading. The running time was 30-40 min. Gene frequencies for ESD were 0.6809 for ESD*1 and 0.3191 for ESD*2, (sigma chi 2 = 0.8586 and P > or = 0.50); gene frequencies of ACP were 0.2009 for ACP*A, 0.7991 for ACP*B, (sigma chi 2 = 1.7892 and P > 0.20), with good agreement between the observed and the expected values.

[Canonical correlation of body composition and pulmonary function in children aged eight to twelve]

Canonical correlation of body composition and pulmonary ventilation function in school boys and girls aged 8 to 12 and normally developed was analyzed. Skinfolds of triceps and subscapular angle were measured, and body composition was estimated as body fat percentage (BF%), body fat (BF) and lean body mass (LBM). Ventilation function was measured. Results indicated that correlation between body composition and ventilation function mainly attributed to a positive correlation between LBM and vital capacity (VC) and a negative correlation between BF% and a ratio of expiratory reserve volume (ERV) to VC. It suggests effects of body composition on ventilation function mainly attributed to LBM and BF%.

Evolutionary stability in the n-person iterated prisoner's dilemma

The iterated prisoner's dilemma game has been used extensively in the study of the evolution of cooperative behaviours in social and biological systems. The concept of evolutionary stability provides a useful tool to analyse strategies for playing the game. Most results on evolutionary stability, however, are based on the 2-person iterated prisoner's dilemma game. This paper extends the results in the 2-person game and shows that no finite mixture of pure strategies in the n-person iterated prisoner's dilemma game can be evolutionarily stable, where n > 2. The paper also shows that evolutionary stability can be achieved if mistakes are allowed in the n-person game.

Recruitment of semiallogeneic dendritic cells to the thymus during post-cyclosporine thymic regeneration

Based on studies of the thymic microenvironment in the model of cyclosporine (CsA)-associated syngeneic graft-versus-host disease, we have hypothesized that immune tolerance develops after CsA is stopped, as the thymus regenerates and recruits new dendritic cells. CsA normally induces medullary involution with destruction of the medullary dendritic cells (DC) and epithelium. This principle could provide practical advantages for transplantation if it is used to recruit new DC into the thymic medulla. Here we administer LEW x BN F1 splenocytes to BN rats and treat them with a short course of CsA. After CsA is stopped, the F1 cells are rapidly recruited to the thymus, and by 10 days after CsA, they are localized at the corticomedullary junction, the natural location of thymic DC. In contrast, dexamethasone, which induces cortical involution, did not lead to thymic recruitment of F1 DC. Recruitment was better if the splenocytes were administered before CsA was stopped. Engraftment of the thymus was also achieved using bone marrow and temporary skin grafts as sources of DC. These observations provide the basis for a novel approach to inducing tolerance to alloantigens with minimal immune suppression and define the goals for further development.

Primary structure and functional expression of a cGMP-gated potassium channel

Cyclic nucleotides modulate potassium (K) channel activity in many cells and are thought to act indirectly by inducing channel protein phosphorylation. Herein we report the isolation from rabbit of a gene encoding a K channel (Kcn1) that is specifically activated by cGMP and not by cAMP. Analysis of the deduced amino acid sequence (725 amino acids) indicates that, in addition to a core region that is highly homologous to Shaker K channels, Kcn1 also contains a cysteine-rich region similar to that of ligand-gated ion channels and a cyclic nucleotide-binding region. Northern blot analysis detects gene expression in kidney, aorta, and brain. Kcn1 represents a class of K channels that may be specifically regulated by cGMP and could play an important role in mediating the effects of substances, such as nitric oxide, that increase intracellular cGMP.

[Effect of tetrandrine on pulmonary hypertension induced by monocrotaline in rats]

The effects of Tetrandrine (Tet) on intraacinous pulmonary arteries (IAPA) and bemodynamics were studied by means of a rat pulmonary hypertension model induced by monocrotaline. The results showed that Tet could reduce the contractive pressure of pulmonary artery, right ventricle and right atrium of heart by 28.0%, 28.3%, and 31.5% respectively. It could also decrease the vascular degeneration of endoepithelial cells of IAPA, the endoepithelial subcavity, the collagens of medial membrane and the numbers of smooth muscles of IAPA.

Hydrocephalus induction in mice infected with herpes simplex virus type 2 after antiviral treatment

By using antiviral chemotherapy to moderate the lethal effect of wild-type herpes simplex virus type 2 (HSV-2), a new mouse model for herpes simplex virus (HSV)-induced hydrocephalus was developed. Groups of BALB/c mice were infected either intracerebrally (i.c.) or intraperitoneally (i.p.) with a lethal dose of HSV-2. The antiviral agent 2'-fluoro-5-methylarabinosyluracil (FMAU) was administered i.p. 2 days after virus inoculation. By day 21, 80 and 71.4% of the mice infected i.c. or i.p., respectively, survived. The surviving animals were randomly subdivided into different groups and some were challenged i.c. or i.p. with a lethal or superlethal dose of homologous virus. The mice were sacrificed at 2 or 3 months after the initial virus infection. Neuropathological changes of the brains were assessed. Dilation of lateral and third ventricles was noted in the animals initially inoculated i.c., especially in all the animals inoculated i.c. and challenged i.c. with a superlethal virus inoculum, but not in those inoculated i.p. Microscopic examination of hydrocephalic brains revealed evidence of viral meningoencephalitis. Two different mechanisms of ventricular enlargement in this animal model are proposed. This model is relevant since HSV-induced cases of hydrocephalus have been reported to occur in humans and in particular neonates. Issues of virus persistence and expression, long-term evaluation for disease progression, and intervention strategies could be examined with this model.

Alternative Function of the Electron Transport System in Azotobacter vinelandii: Removal of Excess Reductant by the Cytochrome d Pathway

The N(inf2)-fixing bacterium Azotobacter vinelandii was grown in an O(inf2)-regulated chemostat with glucose or galactose as substrate. Increasing the O(inf2) partial pressure resulted in identical synthesis of the noncoupled cytochrome d terminal oxidase, which is consistent with the hypothesis that A. vinelandii uses high rates of respiration to protect the nitrogenase from oxygen. However, cell growth on glucose showed a lower yield of biomass, higher glycolytic rate, higher respiratory rate, and lower cytochrome o content than cell growth on galactose. Elemental analysis indicated no appreciable change in the C-to-N ratio of cell cultures, suggesting that the major composition of the cell was not influenced by the carbon source. A poor coordination of glucose and nitrogen metabolisms in A. vinelandii was suggested. The rapid hydrolysis of glucose resulted in carbonaceous accumulation in cells. Thus, Azotobacter species must induce a futile electron transport to protect cells from the high rates of glucose uptake and glycolysis.

[Antiviral activity of tannin from the pericarp of Punica granatum L. against genital Herpes virus in vitro]

Based on cell culture techniques this study has demonstrated that tannin from the pericarp of Punica granatum is an effective component against genital herpes virus (HSV-2). The tannin not only inhibits HSV-2 replication, but also shows stronger effects of killing virus and blocking its absorption to cells.

Expression of Na, K-ATPase alpha and beta isoforms in the neonatal rat cochlea

The postnatal expression of five Na, K-ATPase alpha (alpha 1, alpha 2, alpha 3) and beta (beta 1, beta 2) subunit isoforms in the rat cochlea was investigated by immunocytochemistry. High levels of expression of the alpha 1 and beta 2 isoforms were observed in stria vascularis (SV) at all developmental stages. alpha 1 and beta 1 isoforms showed a distinct time-dependent developmental expression pattern in tissues of the spiral ligament (SL) and spiral limbus (SLi). Limited, temporary expression of alpha 2 and alpha 3 subunit isoforms were found in SV and SL. Expression of each isoform was also seen in organ of Corti (OC), spiral ganglion (SG), cochlear nerve (CN) and Kölliker's Organ (KO). These observations suggest that individual isoforms may exert specific actions postnatally during final cochlear maturation.

Glucocorticoid receptor expression in the postnatal rat cochlea

The glucocorticoid receptor (GR) expression in the neonatal rat cochlea was investigated by utilization of a polyclonal antibody against GR, the immunoreactivity of which exhibited a distinct, age-dependent developmental pattern in tissues of the spiral ligament (SL). Immunostaining of GR appeared initially at the 7th postnatal day (PND), increased rapidly between the 14th and 21st PND, and reached adult-like expression levels by the 21st PND. Less pronounced, developmentally regulated expression patterns of GR were observed in cells of the spiral limbus (SLi), spiral ganglion (SG), organ of Corti (OC), and cochlear nerve (CN). For example, high expression levels of GR were observed in the SLi, SG and OC at 3 PND; subsequently, GR immunoreactivity levels decreased from 7 to 14 PND, and then GR immunoreactivity intensified in these regions by 21 PND. No remarkable changes in GR expression were observed in stria vascularis (SV). These data indicate that GR expression in the inner ear is tissue and age-specific, and that GR expression parallels both Na,K-ATPase expression and endocochlear potential development.

De novo synthesis of glucocorticoid hormone regulated inner ear proteins in rats

Changes of rat inner ear de novo protein synthesis in response to dexamethasone (DEX), a synthetic glucocorticoid, have been analyzed by high resolution two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2D-SDS-PAGE) and fluorography. Two proteins (M(r) 41,000 and 35,000) were amplified and one protein (M(r) 47,000) was suppressed by DEX in a cochlear culture medium. In the culture medium conditioned by vestibular tissue, three proteins (M(r) 67,000, 57,000 and 50,000) were amplified after DEX administration. In cochlear and vestibular tissues, glucocorticoid-responsive protein synthesis was down-regulated by DEX, including two proteins (M(r) 39,000 and 35,000) in the cochlea and five proteins (M(r) 80,000, 64,000, 59,000, 56,000 and 40,000) in the vestibule. The regulation of these inner ear proteins by DEX suggests that glucocorticoid may play an important role in normal inner ear microhomeostasis, as well as in the treatment of some inner ear disorders.

Polarized distribution of actin isoforms in gastric parietal cells

The actin genes encode several structurally similar, but perhaps functionally different, protein isoforms that mediate contractile function in muscle cells and determine the morphology and motility in nonmuscle cells. To reveal the isoform profile in the gastric monomeric actin pool, we purified actin from the cytosol of gastric epithelial cells by DNase I affinity chromatography followed by two-dimensional gel electrophoresis. Actin isoforms were identified by Western blotting with a monoclonal antibody against all actin isoforms and two isoform-specific antibodies against cytoplasmic beta-actin and gamma-actin. Densitometry revealed a ratio for beta-actin/gamma-actin that equaled 0.73 +/- 0.09 in the cytosol. To assess the distribution of actin isoforms in gastric glandular cells in relation to ezrin, a putative membrane-cytoskeleton linker, we carried out double immunofluorescence using actin-isoform-specific antibodies and ezrin antibody. Immunostaining confirmed that ezrin resides mainly in canaliculi and apical plasma membrane of parietal cells. Staining for the beta-actin isoform was intense along the entire gland lumen and within the canaliculi of parietal cells, thus predominantly near the apical membrane of all gastric epithelial cells, although lower levels of beta-actin were also identified near the basolateral membrane. The gamma-actin isoform was distributed heavily near the basolateral membrane of parietal cells, with much less intense staining of parietal cell canaliculi and no staining of apical membranes. Within parietal cells, the cellular localization of beta-actin, but not gamma-actin, isoform superimposed onto that of ezrin. In a search for a possible selective interaction between actin isoforms and ezrin, we carried out immunoprecipitation experiments on gastric membrane extracts in which substantial amounts of actin were co-eluted with ezrin from an anti-ezrin affinity column. The ratio of beta-actin/gamma-actin in the immunoprecipitate (beta/gamma = 2.14 +/- 0.32) was significantly greater than that found in the cytosolic fraction. In summary, we have shown that beta- and gamma-actin isoforms are differentially distributed in gastric parietal cells. Furthermore, our data suggest a preferential, but not exclusive, interaction between beta-actin and ezrin in gastric parietal cells. Finally, our results suggest that the beta- and gamma-actin-based cytoskeleton networks might function separately in response to the stimulation of acid secretion.

Novel furostanol glycosides from Allium macrostemon

Further studies by means of preparative HPLC led to the isolation of two new furostanol saponins, macrostemonosides G (1) and I (3), along with an artifact, macrostemonoside H (2) from the bulbs of Allium macrostemon Bunge. On the basis of chemical evidence and spectral analyses (1H-,13C-NMR,1H-1H COSY,1H-13C COSY, HMBC and FAB-MS), the structure of 1 was established as 26-O-beta-D-glucopyranosyl-22-hydroxy-5 beta-furost-25(27)-ene-3 beta,12 beta,26 triol 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside and 2 as the 22-methoxy derivative of 1; 3 was deduced to be 26-O-beta-D-glucopyranosyl-22-hydroxy-5 beta-furost-25(27)-ene-12-one-3 beta,26- diol 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside. Preliminary pharmacological tests showed that macrostemonoside G (1) could inhibit ADP-induced human platelet aggregation in vitro (IC50 = 0.871 mM).