Effects of Na+, K+ and Mg2+ on45Ca2+ uptake by pancreatic islets

Microdissected pancreatic islets of noninbredob/ob-mice were used to study ionic effects on the lanthanum-nondisplaceable⁴⁵Ca²⁺ uptake by islet cells. Omission of Mg²⁺ from the incubation medium had no effect, but the⁴⁵Ca²⁺ uptake was increased by omission of Na⁺ and decreased by omission of K⁺. Excess Mg²⁺ (1.2–15 mM) inhibited and excess K⁺ (4.7–25 mM) stimulated the⁴⁵Ca²⁺ uptake in a concentration-dependent manner. Stimulation of⁴⁵Ca²⁺ uptake in Na⁺-deficient islets was associated with an enhancement of the basal insulin release. Total abolishment of glucose-stimulated⁴⁵Ca²⁺ uptake in K⁺-deficient islets did not preclude a significant secretory response to glucose. It is concluded that the lanthanum-nondisplaceable⁴⁵Ca²⁺ uptake shows a partial correlation to insulin release.     

P2X receptors in trigeminal subnucleus caudalis modulate central sensitization in trigeminal subnucleus oralis

This study investigated the role of trigeminal subnucleus caudalis (Vc) P2X receptors in the mediation of central sensitization induced in nociceptive neurons in subnucleus oralis (Vo) by mustard oil (MO) application to the tooth pulp in anesthetized rats. MO application produced a long-lasting central sensitization reflected in neuroplastic changes (i.e., increases in neuronal mechanoreceptive field size and responses to innocuous and noxious mechanical stimuli) in Vo nociceptive neurons. Twenty minutes after MO application, the intrathecal (i.t.) administration to the rostral Vc of the selective P2X(1), P2X(3), and P2X(2/3) receptor antagonist, 2'-(or 3'-)O-trinitrophenyl-ATP (TNP-ATP), significantly and reversibly attenuated the MO-induced central sensitization for more than 15 min; saline administration had no effect. Administration to the rostral Vc of the selective P2X(1), P2X(3), and P2X(2/3) receptor agonist, alpha,beta-methylene ATP (alpha,beta-meATP, i.t.) produced abrupt and significant neuroplastic changes in Vo nociceptive neurons, followed by neuronal desensitization as evidenced by the ineffectiveness of a second i.t. application of alpha,beta-meATP and subsequent MO application to the pulp. Administration to the rostral Vc of the selective P2X(1) receptor agonist beta,gamma-methylene ATP (beta,gamma-meATP, i.t.) produced no significant neuroplastic changes per se and did not affect the subsequent MO-induced neuroplastic changes in Vo nociceptive neurons. These results suggest that P2X(3) and possibly also the P2X(2/3) receptor subtypes in Vc may play a role in the initiation and maintenance of central sensitization in Vo nociceptive neurons induced by MO application to the pulp.     

大鼠中缝大核突触囊泡在电针后的变化及其图象分析

应用透射电镜和图象分析方法,对电针后大鼠中缝大核突触前终扣内突触囊泡的数量以及突触前终扣内容物的量的变化进行了研究。结果表明:电针后,中缝大核突触前终扣内圆形清亮囊泡和颗粒囊泡的数量明显减少,突触囊泡聚集并向突触活性带集中。图象分析结果:电针后,突触前终扣内容物的量较对照组明显减少,而且内容物分布不均匀并在突触膜附近集中。本实验为针刺镇痛的理论研究提供了形态学依据。     

Intratracheal administration of liposomal clodronate accelerates alveolar macrophage reconstitution following fetal liver transplantation

To facilitate study of alveolar macrophages in vivo, we developed a method to rapidly and efficiently replace resident alveolar macrophages with macrophages of a different (donor) genotype. Chimeric mice were generated by lethal irradiation followed by fetal liver transplantation (FLT) using green fluorescent protein (GFP) transgenic reporter mice as donors. Kinetics of peripheral blood monocyte (PBM) and alveolar macrophage reconstitution was determined 4 and 10 weeks post-FLT by quantifying the percentage of GFP+ cells. To enhance the recruitment of donor monocytes into the lung after FLT, mice were treated with intratracheal administration of liposomal clodronate to deplete host alveolar macrophages at 6 weeks post-FLT. PBM reconstitution occurred by 4 weeks after FLT (85.7+/-1.6% of CD11b+/Gr-1+ monocytes were GFP+), and minimal alveolar macrophage repopulation was observed (9.5% GFP+). By 10 weeks following FLT, 48% of alveolar macrophages were GFP+ by immunostaining of macrophages on lung tissue sections, and 55.1 +/- 1.6% of lung lavage macrophages were GFP+ by fluorescein-activated cell sorter analysis. Clodronate treatment resulted in a significant increase in GFP+ alveolar macrophages 10 weeks after FLT. By immunostaining, 90% of macrophages were GFP+ on lung tissue sections and 87.5 +/- 1.1% GFP+ in lung lavage (compared with GFP-transgenic controls). The ability of newly recruited alveolar macrophages to clear Pseudomonas aeruginosa and activate nuclear factor-kappaB in response to Eschericia coli lipopolysaccharide demonstrated normal macrophage function. Optimizing this methodology provides an important tool for the study of specific genes and their contribution to alveolar macrophage function in vivo.     

Significant HLA-A02 allelic variation revealed in chinese and caucasian populations

HLA-A2 subtypes (A^*0201 - ^*0212) were determined by oligotyping in HLA-A2 positive samples from four populations (Han Chinese, Dai Chinese, Caucasoids from Germany and Turkish individuals from Kayseri)(see table).

Two different findings can be concluded from this study: 1) Significant HLA-A^*02 allelic variations found in four populations. A^*0207 is the predominant A^*02 allele in the Dai population and absent in the German Caucasian and the Turkish population. In contrast, A^*0201 is the most prevalent allele in the Caucasian, Turkish and Han Chinese group. We also found a high proportion of A^*0206 and A^*0207 in Han Chinese. 2) A strong association has been found between A^*0207 and HLA-B46 and DR9 in the Dai minority population. This haplotype is also found in Han Chinese. Three DNA samples from Turkish and one from the Dai population are presently being sequenced because the reaction pattern was out of the expected (Supported by SFB 217)     

The catalytic subunit of cyclic AMP-dependent protein kinase directly inhibits sodium channel activities in guinea-pig ventricular myocytes

We investigated the effects of the purified catalytic subunit (C subunit) of the cAMP-dependent protein kinase (A-kinase) on the cardiac Na⁺ channel currents. Single Na⁺ channel currents in guinea-pig ventricular myocytes were recorded using the patch clamp technique of the inside-out configuration. Application of C subunit decreased the peak average current and slowed the current decay, effects which were caused by decrease in the open probability of Na⁺ channels and increase in the first latency, whereas the unitary current amplitude and mean open times were not affected. We conclude that the cardiac Na⁺ channel is directly modulated by phosphorylation process through A-kinase.     

Studies on the Histamine Releasing Effect of Bee Venom Fractions and Compound 48/80 on Skin and Lung Tissue of the Rat

Two bee venom fractions, F I and F II, obtained by gel filtration, and compound 48/80, were shown to release histamine from skin and lung tissue of the rat. F I is the phosphatidase A containing fraction, and F II contains a basic polypeptide. Dose-response relationships, the time course of the histamine release, and the influence of enzyme inhibitors were studied. The results with F II and compound 48/80 were similar, suggesting that the two substances activate the same kind of release mechanism. It is concluded that F II is not related to the earlier described bee venom polypeptides melittin and aparnin. The mode of action of phosphatidase A was distinctly different from that of F II or compound 48/80. The results are consistent with the assumption that it acts in a “non-specific.” way by hydrolysing tissue phosphatides to lyso compounds, which in turn damage the tissue.     

Changes of interleukin expression correlate with Helicobacter pylori infection and lymph node metastases in gastric carcinoma.

Helicobacter pylori (HP) infection induces expression of IL-8 and IL-10 in benign gastric epithelium. This study compared the expression of cytokines in CD4+ and CD8+ lymphocyte subsets of peripheral blood lymphocytes (PBL), benign mucosal lymphocytes (ML), and tumor infiltrative lymphocytes (TIL) as well as in the benign and malignant epithelial cells of the same patient, with respect to the presence of HP infection, lymph node metastases, and tumor histologic type. The mRNA of the cytokines was measured by a semiquantitative RT-PCR method. The levels were ranked and compared using the Wilcoxon sign-ranked test. Compared with CD8+ ML, the CD8+ TIL expresses higher levels of IL-6 and IL-8 but lower level of IL-4 in patients with lymph node metastases. In patients with HP infection, expression of IL-8 and IL-10 was higher in the gastric carcinoma cells than in the benign epithelial cells while expression of IL-6 and IL-8 were higher in CD8+ TIL than CD8+ ML. Overexpression of IL-8 in HP associated gastric carcinomas suggested that they might have arisen from HP-infected epithelial cells.     

Identification and functional analysis of mutations in the hypocretin (orexin) genes of narcoleptic canines

Narcolepsy is a sleep disorder affecting animals and humans. Exon skipping mutations of the Hypocretin/Orexin-receptor-2 (Hcrtr2) gene were identified as the cause of narcolepsy in Dobermans and Labradors. Preprohypocretin (Hcrt) knockout mice have symptoms similar to human and canine narcolepsy. In this study, 11 sporadic cases of canine narcolepsy and two additional multiplex families were investigated for possible Hcrt and Hcrtr2 mutations. Sporadic cases have been shown to have more variable disease onset, increased disease severity, and undetectable Hypocretin-1 levels in cerebrospinal fluid. The canine Hcrt locus was isolated and characterized for this project. Only one novel mutation was identified in these two loci. This alteration results in a single amino acid substitution (E54K) in the N-terminal region of the Hcrtr2 receptor and autosomal recessive transmission in a Dachshund family. Functional analysis of previously-described exon-skipping mutations and of the E54K substitution were also performed using HEK-293 cell lines transfected with wild-type and mutated constructs. Results indicate a truncated Hcrtr2 protein, an absence of proper membrane localization, and undetectable binding and signal transduction for exon-skipping mutated constructs. In contrast, the E54K abnormality was associated with proper membrane localization, loss of ligand binding, and dramatically diminished calcium mobilization on activation of the receptor. These results are consistent with a loss of function for all three mutations. The absence of mutation in sporadic cases also indicates genetic heterogeneity in canine narcolepsy, as reported previously in humans.