A developmental change in NMDA receptor-associated proteins at hippocampal synapses

The membrane-associated guanylate kinases [Chapsyn-110/postsynaptic density-93 (PSD-93), synapse-associated protein-90 (SAP-90)/PSD-95, and SAP-102] are believed to cluster and anchor NMDA receptors at the synapse and to play a role in signal transduction. We have investigated the developmental changes in expression of these proteins in rat hippocampus using biochemical analyses and quantitative immunogold electron microscopy. At postnatal day 2 (P2), SAP-102 was highly expressed, whereas PSD-93 and PSD-95 were low. SAP-102 expression increased during the first week, stayed stable through P35, and showed a reduced expression at 6 months. From P2 through 6 months, PSD-93 and PSD-95 increased. For PSD-95, the percent of labeled synapses increased almost threefold with age, whereas the number of gold particles per labeled synapse did not change significantly, suggesting that the increase in PSD-95 is attributable primarily to an increase in the number of synapses containing PSD-95. In contrast, for SAP-102, both percent labeled synapses and the number of gold particles per labeled synapse decreased during this time. From Western blots of hippocampus and immunogold analysis of CA1 synapses, the high expression of NR2B at P2 coincides with the high level of SAP-102 at synapses, whereas the later expression of NR2A coincides with that of PSD-93 and PSD-95. To determine whether the changes in PSD-93/95 and SAP-102 reflect preferred associations with NR2A and NR2B, respectively, we measured co-immunoprecipitation in the adult hippocampus. These studies suggest that there is a preference for complexes of NR2A/PSD-93/95 and NR2B/SAP-102. These results indicate that individual receptor-associated proteins may have specific functions that are critical to synapse development.

Increased aortic stiffness assessed by pulse wave velocity in apolipoprotein E-deficient mice

Atherosclerosis develops and progresses spontaneously in apolipoprotein E-knockout (apoE-KO) mice. A direct consequence of atherosclerosis is an increase in vascular stiffness. Pulse wave velocity (PWV) has been used to assess the stiffness of large vessels and was found to be increased in patients with atherosclerosis. In the present study, aortic stiffness was assessed by PWV in 4- and 13-mo-old apoE-KO mice and age-matched controls (C57BL/6J). In 13-mo-old apoE-KO mice with extensive atherosclerotic lesions in the aorta (61 +/- 4%), PWV increased significantly (3.8 +/- 0.2 m/s) compared with controls (2.9 +/- 0.2 m/s). Endothelial nitric oxide (EDNO)-mediated vasorelaxation in response to ACh was markedly diminished in the aortic rings isolated from 13-mo-old apoE-KO mice compared with age-matched controls. In contrast, in 4-mo-old apoE-KO mice with only moderate atherosclerotic lesions in the aorta (23 +/- 5%), there were no significant changes in PWV and EDNO-mediated relaxation compared with controls. Blood pressure was not different among the four groups of mice. There were no significant differences in endothelium-independent vascular responses to sodium nitroprusside among different groups investigated. Histological evaluation revealed focal fragmentation of the elastic laminae in the aortic walls of 13-mo-old apoE-KO mice. These results demonstrate for the first time that aortic stiffness determined by PWV increases in 13-mo-old apoE-KO mice. Endothelial dysfunction and elastic destruction in vascular wall caused by atherosclerosis may have contributed.

Interleukin-2: structural and biological relatedness to opioid peptides

Interleukin (IL)-2 is not only an immunoregulatory factor, but also an analgesic molecule. There are distinct domains of immune and analgesic functions in the IL-2 molecule. The analgesic domain is located around the 45th Tyr residue of human IL-2 in tertiary structure. Antiopioid (beta-endorphin, Leu-enkephalin, Met-enkephalin and dynorphin A1-13) sera partially neutralized the analgesic activity of IL-2. Monoclonal antibody against the IL-2 receptor alpha subunit (Tac) could not block the analgesic activity of IL-2. There existed cross-reactivity between IL-2 and antiopioid sera by indirect ELISA. These studies show strong structural and biological similarities between IL-2 and opioid peptides. The tertiary structure around the 45th residue of IL-2 composes the analgesic domain that is similar to that of endogenous opioids. These results are consistent with the hypothesis that multiple domains of cytokines serve as the structural bases for the immunoregulatory and neuroregulatory effects of cytokines.

Anti-HIV and anti-tumor protein MAP30, a 30 kDa single-strand type-I RIP, shares similar secondary structure and beta-sheet topology with the A chain of ricin, a type-II RIP

MAP30 is a 30 kDa single-stranded, type-I ribosome inactivating protein (RIP) possessing anti-tumor and anti-HIV activities. It binds both ribosomal RNA and the HIV-1 long-terminal repeat DNA. To understand the structural basis for MAP30 activities, we undertook the study of MAP30 by solution NMR spectroscopy. We report nearly complete 1H, 13C, and 15N chemical shift assignments of its 263 amino acids. Based upon an analysis of secondary 13C chemical shifts, 3J(HNHA) coupling constants, hydrogen exchange data, and nuclear Overhauser effect patterns, we find that the secondary structure and beta-sheet topology of MAP30 are very similar to those of the ricin A chain, a subunit of the well-known type-II RIP, even though two proteins display distinct activities. We therefore suggest that MAP30 and ricin A chain share a similar three-dimensional fold, and that the reported functional differences between two proteins arise primarily from differences in local three-dimensional structure and other structural properties such as surface electrostatic potentials.

Vasodilator effects of organotransition-metal nitrosyl complexes, novel nitric oxide donors

Nitrovasodilators cause endothelium-independent relaxation of blood vessels by generating nitric oxide (NO). We examined the relaxation and depressor effects of two organotransition-metal nitrosyl complexes, CpCr(NO)2Cl and CpMo(NO)2Cl, relative to those of the prototypal nitrovasodilators, nitroglycerin, and sodium nitroprusside (SNP), in phenylephrine-preconstricted aortic rings and conscious, unrestrained rats. CpCr(NO)2Cl, CpMo(NO)2Cl, nitroglycerin and SNP caused dose-dependent relaxation of aortic rings at maximal responses (Emax) of -118+/-4, -113+/-4, -104+/-1, and -128+/-5% and EC50 of 0.14+/-0.04, 22+/-4, 1.23+/-0.65, and 0.063+/-0.013 microM, respectively. The dose-response curve of CpCr(NO)2Cl was displaced to the right by hemoglobin, as well as methylene blue, showing involvement of the NO/cGMP pathway. Unlike nitroglycerin, preexposure for 1 h to CpCr(NO)2Cl did not alter subsequent relaxation response to the compound. Intravenous bolus injections of CpCr(NO)2Cl, CpMo(NO)2Cl, nitroglycerin, and SNP caused dose-dependent decreases in MAP with Emax of -42+/-2, -51+/-8, -56+/-6, and -58+/-2 mm Hg and EC50 of 0.041+/-0.010, 13+/-4, 1.6+/-0.4, and 0.037+/-0.004 micromol/kg, respectively. These results show that CpCr(NO)2Cl and CpMo(NO)2Cl are efficacious nitrovasodilators in vitro and in vivo.

Antinociceptive properties of fenfluramine, a serotonin reuptake inhibitor, in a rat model of neuropathy

Fenfluramine is an indirect agonist of 5-hydroxytryptamine (5-HT) receptors that acts by evoking 5-HT release and blocking 5-HT reuptake in neuronal cells. The current study compared the antinociceptive properties of fenfluramine with those of the tricyclic antidepressants amitriptyline and desipramine in rat models of acute, persistent, and neuropathic pain. In a rat model of neuropathic pain produced by tight ligation of the L(5)/L(6) spinal nerves, i.v. bolus injection of fenfluramine resulted in a dose-dependent and long-lasting (>4 h) blockade of mechanical allodynia (ED(50) = 3.5 mg/kg; 95% confidence interval, 2.2-5.4 mg/kg) and cold allodynia (ED(50) = 2.4 mg/kg; 95% confidence range, 1.2-4.6 mg/kg). Fenfluramine also prevented tonic pain evoked by the s.c. injection of dilute (5%) formaldehyde solution (formalin), into the dorsal hindpaw. The i.v. administration of amitriptyline (4.7 mg/kg) or desipramine (13.5 mg/kg) at maximum tolerated doses did not block either allodynia in rats with spinal nerve ligation-induced painful neuropathy or tonic pain in the formalin test. Fenfluramine had differential effects on acute behavioral responses to noxious thermal (heat), chemical (5% formaldehyde solution), and mechanical stimuli; it completely inhibited nociceptive behavior in the acute phase of the formaldehyde solution test and partially inhibited licking and jumping responses in the hot-plate test but did not alter nociceptive thresholds in either the paw pressure test or the tail immersion test. Intracerebroventricular bolus injection of 240 microg of fenfluramine significantly increased mechanical allodynia thresholds; however, the same dose administered spinally by intrathecal bolus injection was ineffective. The inhibitory effects of fenfluramine on mechanical allodynia (and tonic pain behavior in the formaldehyde solution test) were prevented by pretreatment with 10 mg/kg metergoline, a selective antagonist of 5-HT receptors, but not with the mu-opioid receptor antagonist naloxone. These results suggest that fenfluramine produces analgesia in the formaldehyde solution test and the spinal nerve ligation model of neuropathic pain by potentiating, at least in part, supraspinal 5-HT mediated processes.

Solution structure of anti-HIV-1 and anti-tumor protein MAP30: structural insights into its multiple functions

We present the solution structure of MAP30, a plant protein with anti-HIV and anti-tumor activities. Structural analysis and subsequent biochemical assays lead to several novel discoveries. First, MAP30 acts like a DNA glycosylase/apurinic (ap) lyase, an additional activity distinct from its known RNA N-glycosidase activity toward the 28S rRNA. Glycosylase/ap lyase activity explains MAP30's apparent inhibition of the HIV-1 integrase, MAP30's ability to irreversibly relax supercoiled DNA, and may be an alternative cytotoxic pathway that contributes to MAP30's anti-HIV/anti-tumor activities. Second, two distinct, but contiguous, subsites are responsible for MAP30's glycosylase/ap lyase activity. Third, Mn2+ and Zn2+ interact with negatively charged surfaces next to the catalytic sites, facilitating DNA substrate binding instead of directly participating in catalysis.

Synthesis of a series of 4-benzyloxyaniline analogues as neuronal N-type calcium channel blockers with improved anticonvulsant and analgesic properties

In this article, the rationale for the design, synthesis, and biological evaluation of a series of N-type voltage-sensitive calcium channel (VSCC) blockers is described. N-Type VSCC blockers, such as ziconotide, have shown utility in several models of stroke and pain. Modification of the previously reported lead, 1a, led to several 4-(4-benzyloxylphenyl)piperidine structures with potent in vitro and in vivo activities. In this series, the most interesting compound, (S)-2-amino-1-{4-[(4-benzyloxy-phenyl)-(3-methyl-but-2-enyl)-amino]-p iperidin-1-yl}-4-methyl-pentan-1-one (11), blocked N-type calcium channels (IC(50) = 0.67 microM in the IMR32 assay) and was efficacious in the audiogenic DBA/2 seizure mouse model (ED(50) = 6 mg/kg, iv) as well as the antiwrithing model (ED(50) = 6 mg/kg, iv). Whole-cell voltage-clamp electrophysiology experiments demonstrated that compound 11 blocked N-type Ca(2+) channels and Na(+) channels in superior cervical ganglion neurons at similar concentrations. Compound 11, which showed superior in vivo efficacy, stands out as an interesting lead for further development of neurotherapeutic agents in this series.

CT of adrenal myelolipoma: report of 7 cases

Seven cases of adrenal myelolipoma are reported. The series consisted of 1 male and 6 females, ranging in age from 30 to 76 years. In 5 cases the tumor originated from the right adrenal, in 1 case from the left adrenal and the remaining patients had bilateral tumors. Symptoms related to the mass were present in 4 cases but in contrast to other reports no hematuria was found in this series. All the tumors laid behind the angles formed by the lateral and medial limbs of adrenals. Fat density dominated in 6 tumors and soft tissue density dominated in 2. Calcification spots were revealed in 3 tumors. In two predominantly soft tissue density tumors the complete peripheral rims were revealed, while in the remaining 6 tumors the peripheral rims were considered incomplete based on the CT images. In 3 cases large amounts of fat were found surrounding the normal contralateral adrenal. The cause is still open to further investigation. Spiral CT with thin collimation provided detailed morphological information for adrenal myelolipoma.

Flap opening and dimer-interface flexibility in the free and inhibitor-bound HIV protease, and their implications for function

BACKGROUND

(1)H and (15)N transverse relaxation measurements on perdeuterated proteins are ideally suited for detecting backbone conformational fluctuations on the millisecond-microsecond timescale. The identification of conformational exchange on this timescale by measuring the relaxation of both (1)H and (15)N holds great promise for the elucidation of functionally relevant conformational changes in proteins.

RESULTS

We measured the transverse (1)H and (15)N relaxation rates of backbone amides of HIV-1 protease in its free and inhibitor-bound forms. An analysis of these rates, obtained as a function of the effective rotating frame field, provided information about the timescale of structural fluctuations in several regions of the protein. The flaps that cover the active site of the inhibitor-bound protein undergo significant changes of backbone (φ,psi) angles, on the 100 micros timescale, in the free protein. In addition, the intermonomer beta-sheet interface of the bound form, which from protease structure studies appears to be rigid, was found to fluctuate on the millisecond timescale.

CONCLUSIONS

We present a working model of the flap-opening mechanism in free HIV-1 protease which involves a transition from a semi-open to an open conformation that is facilitated by interaction of the Phe53 ring with the substrate. We also identify a surprising fluctuation of the beta-sheet intermonomer interface that suggests a structural requirement for maturation of the protease. Thus, slow conformational fluctuations identified by (1)H and (15)N transverse relaxation measurements can be related to the biological functions of proteins.

Cerebral asymmetry in a selected Chinese population

Previous studies have demonstrated anatomical differences between the two cerebral hemispheres and ethnic differences in cerebral asymmetry. This study examined asymmetry of Chinese living in Shanghai. Measurements were taken across the frontal, mid-cerebral and occipital regions from normal head computed tomography (CT) scans of 200 Chinese Shanghai residents (100 male and 100 female, aged 6-73 years, average 48.7 years). The results were compared with reported data in the literature. The following results were found: (i) In the frontal region the right side was larger than the left in 57.5% of cases, equal in 10.5% and smaller in 32% of cases; in the mid-cerebral region the right side was larger than the left in 65.5% of cases, equal in 12.5% and smaller in 22% of cases; in the occipital regions the right side was larger than the left in 34.5% of cases, equal in 8.5% and smaller in 57% of cases. The average right-left differences between the frontal, mid-cerebral and occipital regions were 0.43 mm, 0.9 mm and 0.4 mm respectively. No difference in cerebral asymmetry existed between males and females. The occipital lobes showed the greatest individual asymmetry. The distribution of cerebral asymmetry of Chinese in Shanghai showed similarity to North American Whites rather than North American Blacks, but the average right-left differences were smaller than those of Whites.

Phylogenetic study of complete cytochrome b genes in musk deer (genus Moschus) using museum samples

As an endangered animal group, musk deer (genus Moschus) are not only a great concern of wildlife conservation, but also of special interest to evolutionary studies due to long-standing arguments on the taxonomic and phylogenetic associations in this group. Using museum samples, we sequenced complete mitochondrial cytochrome b genes (1140 bp) of all suggested species of musk deer in order to reconstruct their phylogenetic history through molecular information. Our results showed that the cytochrome b gene tree is rather robust and concurred for all the algorithms employed (parsimony, maximum likelihood, and distance methods). Further, the relative rate test indicated a constant sequence substitution rate among all the species, permitting the dating of divergence events by molecular clock. According to the molecular topology, M. moschiferus branched off the earliest from a common ancestor of musk deer (about 700,000 years ago); then followed the bifurcation forming the M. berezovskii lineage and the lineage clustering M. fuscus, M. chrysogaster, and M. leucogaster (around 370,000 years before present). Interestingly, the most recent speciation event in musk deer happened rather recently (140,000 years ago), which might have resulted from the diversified habitats and geographic barriers in southwest China caused by gigantic movements of the Qinghai-Tibetan Plateau in history. Combining the data of current distributions, fossil records, and molecular data of this study, we suggest that the historical dispersion of musk deer might be from north to south in China. Additionally, in our further analyses involving other pecora species, musk deer was strongly supported as a monophyletic group and a valid family in Artiodactyla, closely related to Cervidae.

RADHA--a new male germ line-specific chromosomal protein of Drosophila

A new chromosomal protein - RADHA - of Drosophila is described that is specific for the male germ line. It is encoded by a single-copy gene, located in the region 96C-D of D. melanogaster polytene chromosomes. Transcription of the radha gene is restricted to the primary spermatocyte stage. The protein initially accumulates in some of the Y-chromosomal lampbrush loops. After meiosis it is found in the nuclei of spermatids and might be involved in chromatin rearrangement processes in the male germ line. RADHA is a basic protein with a C-terminal leucine zipper region and several segments capable of forming coiled-coil structures.

Measurement of 3hJNC' connectivities across hydrogen bonds in a 30 kDa protein

A method is described which permits detection of 3hJNC' scalar couplings across hydrogen bonds in larger, perdeuterated proteins. The experiment is demonstrated for the uniformly 2H/13C/15N-enriched 30 kDa ribosome inactivating protein MAP30. The 3hJNC' interactions are smaller than 1 Hz, but their detection in an HNCO experiment is made possible through the use of constructive interference between the 15N chemical shift anisotropy and 1H-15N dipole-dipole relaxation mechanisms in a manner similar to that of recently proposed TROSY schemes. Sensitivity of the HNCO experiment depends strongly on the 15N transverse relaxation rate of the downfield 15N multiplet component and on the amide proton T1. In perdeuterated MAP30 at 40 degrees C, the average TROSY T2 was 169 ms at 750 MHz 1H frequency, and a wide range of longitudinal relaxation rates was observed for the amide protons.

Genotoxicity of water samples from Dianchi lake detected by the Vicia faba micronucleus test

Dianchi Lake covers about a 300 km2 area. Kunming city on the edge of the lake is surrounded by industrial establishments. Farm land surrounds the remaining areas of the lake. The lake water is polluted by the Kunming city municipal sewage from 3 million inhabitants, the industrial effluent and farm runoff. Water samples were collected from 12 sites along the shore of the lake during the dry (May) and rainy (August) seasons for genotoxicity testing with the Vicia micronucleus assay during the year 1995. Genotoxicity in terms of micronuclei (MCN) frequencies in the root tip cells of Vicia showed a consistent elevated frequency of MCN over the control sample at the 0.05-0.01 levels of significance in both seasons. The MCN frequencies of sites A (Daguanhe), B (Gaoqiao) and C (Xiyuan) were 3.5-4 times as high as the control values (5.25/1000 cells) in the dry season. In the rainy season, the MCN frequencies of water samples from most of the 12 sites were relatively lower than those of the dry season except sites J (Haikou), and K (Kunyang). The average MCN frequency of the dry season samples was 14.97 per 1000 cells and that of the rainy season samples was 12.24 per 1000 cells while the average control value was around 5.00/1000 cells.

Postsynaptic density-93 interacts with the delta2 glutamate receptor subunit at parallel fiber synapses

The glutamate receptor subunit delta2 has a unique distribution at the parallel fiber-Purkinje cell synapse of the cerebellum, which is developmentally regulated such that delta2 occurs at both parallel fiber synapses and climbing fiber synapses early in development but is restricted to parallel fiber synapses in adult animals. To identify proteins that might be involved in the trafficking or docking of delta2 receptors, we screened a yeast two-hybrid library with the cytosolic C terminus of delta2 and isolated a member of the postsynaptic density (PSD)-95 family of proteins, which are known to interact with the extreme C termini of NMDA receptors. We find that delta2 binds specifically to PSD-93, which is enriched in Purkinje cells. In addition, PSD-93 clusters delta2 when they are coexpressed in heterologous cells, and clustering is disrupted by point mutations of delta2 that disrupt the delta2-PSD-93 interaction. Ultrastructural localization of PSD-93 and delta2 shows they are colocalized at parallel fiber synapses; however, PSD-93 also is present at climbing fiber synapses of the adult rat, where delta2 is not found, indicating that the presence of PSD-93 alone is not sufficient for determining the synaptic expression of delta2.

Coupling of M2 muscarinic receptors to membrane ion channels via phosphoinositide 3-kinase gamma and atypical protein kinase C

We report a novel signaling pathway linking M2 muscarinic receptors to metabotropic ion channels. Stimulation of heterologously expressed M2 receptors, but not other Gi/Go-associated receptors (M4 or alpha2c), activates a calcium- and voltage-independent chloride current in Xenopus oocytes. We show that the stimulatory pathway linking M2 receptors to these chloride channels consists of Gbeta gamma stimulation of phosphoinositide 3-kinase gamma (PI-3Kgamma), formation of phosphatidylinositol 3,4,5-trisphosphate (PIP3), and activation of atypical protein kinase C (PKC). The chloride current is activated in the absence of M2 receptor stimulation by the injection of PIP3, and PIP3 current activation is blocked by a pseudosubstrate inhibitory peptide of atypical PKC but not other PKCs. Moreover, the current is activated by injection of recombinant PKCzeta at concentrations as low as 1 nM. M2 receptor-current coupling was disrupted by inhibiton of PI-3K and by injection of beta gamma binding peptides, but it was not affected by expression of dominant negative p85 cRNA. We also show that this pathway mediates M2 receptor coupling to metabotropic nonselective cation channels in mammalian smooth muscle cells, thus demonstrating the broad relevance of this signaling cascade in neurotransmitter signaling.

Apoptosis and necrosis induced by sulfur mustard in Hela cells

AIM

To study the apoptotic effect of sulfur mustard (SM) on Hela cells.

METHODS

Exponentially growing Hela cells were treated with SM at various concentrations for 3 h, then apoptosis was examined by electron-microscope, DNA gel electrophoresis, and flow cytometry.

RESULTS

SM 1 mumol.L-1 arrested cell growth. After treatment with SM 10-100 mumol.L-1, cells were mainly blocked at G1-phase with apoptosis. Agarose gel electrophoresis of DNA from cells treated with SM revealed "DNA Ladder." About 33% of the Hela cells showed apoptosis 12 h after 3-h treatment with SM 100 mumol.L-1 as determined by flow cytometry and the S-phase cells were more susceptible. However, SM 1000 mumol.L-1 caused marked necrosis in Hela cells.

CONCLUSION

SM caused 2 distinct forms of cell death, apoptosis or necrosis, in Hela cells in a concentration-dependent manner.

M2 signaling in smooth muscle cells

M2 receptor stimulation results in the gating of nonselective cation channels in several smooth muscle cell types. However the requirement for current activation includes a rise in cytosolic calcium mediated by M3 receptor induced calcium release. This complex signaling system confers substantial complexity on the interpretation of pharmacological experiments. M2 and M3 receptor stimulation has also been linked to the inhibition of potassium channels in smooth muscle. These signaling events are likely to play important roles in excitation/contraction coupling.

Bilateral kidney ligation abolishes pressor response to N(G)-nitro-D-arginine

We have shown that N(G)-nitro-D-arginine (D-NNA) is 50% as potent as N(G)-nitro-L-arginine (L-NNA) in causing pressor response and 2-3% as potent as L-NNA in inhibiting endothelium-dependent relaxation in vitro. These results suggest in vivo activation of D-NNA. Furthermore, the potency of D-NNA was markedly increased after it had been incubated with homogenate of the kidney, but not plasma or homogenate of the aorta, lungs or liver. This study examined if bilateral ligation of the kidneys attenuated the biological action of D-NNA. I.v. bolus of D-NNA (16 mg/kg), L-NNA (3 mg/kg) and norepinephrine (0.25-16 microg/kg) increased arterial pressure in sham-operated rats. Bilateral ligation of the kidneys abolished pressor response to D-NNA, but not L-NNA and norepinephrine. I.v. bolus D-NNA in sham-operated rats, but not kidney-ligated rats, inhibited relaxation response to acetylcholine in pre-constricted aortic rings ex vivo. These results indicate that the kidney is the primary organ which activates D-NNA.

Prophylactic effect of methylene blue against neurotoxicity of sodium nitroprusside

AIM

To examine the effect of methylene blue (MB) on cytotoxicities of sodium nitroprusside (SNP) and cyclic guanosine monophosphate (cGMP) in cultivated cerebellar neurons.

METHODS

The cytotoxicities of xenobiotic SNP and cGMP on cultivated murine cerebellar neurons were examined according to Dessi's method. Toxicity of SNP i.c.v. to mice and the prophylactic effect of i.c.v. MB were investigated with respect to the incidence of seizure and the mortality of mice within 24 h.

RESULTS

Ten min treatment of SNP 1 mmol.L-1 decreased the survival rate of murine cerebellar nerve cells from 92% of normal control to 35%. Incubation with cGMP 0.1 mmol.L-1 for 1 h declined the survival rate from 94% of normal to 40%. Injection i.c.v. SNP 20 nmol killed one tenth of the mice in 24 h, and SNP 30 nmol killed 11/13 of the mice. MB (100 nmol) i.c.v. injection protected 11/13 of the mice against seizure and death caused by SNP (30 nmol, i.c.v.), and completely eliminated the toxicity of SNP 20 nmol.

CONCLUSION

SNP and cGMP inhibit the vitality of murine neurons in vitro. MB injection i.c.v. markedly antagonizes the dose-dependent neuron-toxic effect of SNP in respect of convulsion and mortality of mice.

CT findings in congenital adrenal hyperplasia due to 11 beta hydroxylase deficiency at puberty age

The CT findings of a case of congenital adrenal hyperplasia due to 11 beta hydroxylase deficiency at the age of 17 is presented. CT showed marked bilateral symmetric adrenal enlargement with smooth borders. In upper parts of the enlarged adrenals the contours were preserved, but the lower parts of the adrenals appeared ball-like. The adrenals were homogeneous in density before contrast, after administration of iodinated contrast agent the glands were markedly enhanced with obvious vasculature observed. These CT findings were pathognomonic of congenital adrenal hyperplasia, though not specific for the type of 11 beta hydroxylase deficiency.

Selective acquisition of AMPA receptors over postnatal development suggests a molecular basis for silent synapses

Early in postnatal development, glutamatergic synapses transmit primarily through NMDA receptors. As development progresses, synapses acquire AMPA receptor function. The molecular basis of these physiological observations is not known. Here we examined single excitatory synapses with immunogold electron-microscopic analysis of AMPA and NMDA receptors along with electrophysiological measurements. Early in postnatal development, a significant fraction of excitatory synapses had NMDA receptors and lacked AMPA receptors. As development progressed, synapses acquired AMPA receptors with little change in NMDA receptor number. Thus, synapses with NMDA receptors but no AMPA receptors can account for the electrophysiologically observed 'silent synapse'.

Calcium release and calcium-activated chloride channels in airway smooth muscle cells

Rapid progress has been made in the determination of specific ion channels expressed in airway smooth muscle cells and their role in excitation-contraction coupling. The combination of molecular biology and molecular physiology has provided insight into the properties of voltage-dependent cation (calcium and potassium) channels and their regulation by excitatory and inhibitory signaling processes. In this brief review, we will focus on calcium release and calcium-activated chloride channels. The former channels mediate receptor-activated calcium release, and the latter channels are opened following this release event. Moreover, the discovery of spontaneous calcium release events, or "calcium sparks," in smooth muscle, suggests an unanticipated level of regulation. Intracellular calcium release can drive electrical activity by the activation of calcium-dependent sarcolemmal ion channels, including calcium-activated chloride channels. These channels activate briefly but undergo a rapid phosphorylation by calcium/calmodulin-dependent protein kinase, which uncouples channel activity from cytosolic calcium. The coupling between intracellular calcium release and depolarizing chloride currents represents a potentially important signaling system in airway smooth muscle.

[Anti-atrial fibrillation effects of cyclovirobuxine-D and its electrophysiological mechanism studied on guinea pig atria]

Cyclovirobuxine-D (CVB-D) was shown to produce significant and dose-dependent protective effects against atrial fibrillation induced by CaCl2-Ach in mice. On atrial fibrillation induced by aconitine, ouabain or adrenaline in isolated guinea pig atria, the effects of CVB-D were similar to those of amiodarone. CVB-D 0.3-100 mumol.L-1 was shown to depress the automaticity of the isolated guinea pig right atria. In isolated left atria, CVB-D 0.3 mumol.L-1 was found to inhibit the abnormal automaticity elicited by adrenaline, to prolong the duration of action potential and effective refractory period and to reduce excitability. At high concentration (30 mumol.L-1), CVB-D was also found to decrease the maximal velocity of depolarization (Vmax) and to elongate the conduction time of initiation. Amiodarone 0.3-30 mumol.L-1 was shown to closely resemble CVB-D in electrophysiology without effect on Vmax.

[Relaxing effects of l-stepholidine on rat resistance arteries]

Bolus injection(i.v.) of l-stepholidine(l-SPD, 3 mg.kg-1) caused hypotension in anaesthetized rats. The blood pressure reduction was sustained for 46.3 +/- 14.1 min. In in vitro experiments, l-SPD induced a concentration dependent relaxation of rat mesenteric, cerebral, renal and coronary resistance arteries preconstricted with 125 mmol.L-1 KCl. l-SPD was least potent with cerebral resistance arteries with the -Log EC50 value being 4.25 +/- 0.22. The relaxation of l-SPD on mesenteric resistance arteries was the most potent with the -Log EC50 value being 4.76 +/- 0.15. The larger influence of l-SPD (100 mumol.L-1) on the contraction induced by KCl in mesenteric than in cerebral arteries was in line with the above results. It is indicated that l-SPD has a direct relaxation on visceral resistance arteries with some degree of selectivity and the relaxation would decrease total peripheral resistance and thus constitute an important cause of its hypotensive action.

Variations in the tangential distribution of postsynaptic glutamate receptors in Purkinje cell parallel and climbing fiber synapses during development

Major factors affecting the responses of a neuron to release of glutamate include the kinds and distribution of glutamate receptors in the neuron and their distribution along the surface of the postsynaptic membrane (tangential distribution). The latter distribution pattern is established during the development of the synapse and could be modified during maturation of synapse structure/function and through adult synapse plasticity. Parallel and climbing fiber synapses of cerebellar Purkinje cells are good models for studying this pattern because they contain two major kinds of ionotropic glutamate receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and delta, that are involved in adult plasticity and show differences in distribution, and because these two synapse types show complex changes in architecture and glutamate receptor distributions during development. In the present study, both AMPA and delta receptors showed variations in tangential distributions during many stages of development from postnatal day 2 to adult; i.e. qualitative assessment showed that receptors are concentrated either near the center or in outer portions of the synapse, while they are rare or absent from the perisynaptic region. Quantitative analysis showed statistically significant nonuniformities at some ages; the most common nonuniformity in these cases appears to be a drop-off in receptor density in the outer 20% of the synapse. Statistical analyses also indicated that distribution patterns did not change significantly with age. In contrast to the ionotropic receptors, the metabotropic glutamate receptor, mGluR1alpha, was found mainly in the perisynaptic region both during development and in adults. Differences in the distribution of glutamate receptors may be necessary to assure an effective response to glutamate release and may be modified through synaptic plasticity. Our findings show that the basic patterns of distribution of ionotropic and metabotropic glutamate receptors in synapses are established early in development, indicating that the postsynaptic density/membrane region is highly organized even in the immature synapse.

CT findings of adrenal glands in patients with tuberculous Addison's disease

The CT findings of adrenals in 18 cases of tuberculous Addison's disease are reported. All cases demonstrated bilateral adrenal involvement, 35 glands with active tuberculosis appeared enlarged and one with non-active tuberculosis showed an atrophic gland with calcification. Areas of non-enhancing necrosis in the enlarged adrenals were seen in 34 glands (17 cases), among them 19 glands showed peripheral rim enhancement. In the 35 enlarged adrenals 25 glands had preserved contours. Small calcification dots in the adrenals were seen in 7 glands with active tuberculosis (4 cases). The CT signs of active tuberculous adrenalitis associated with Addison's disease were enlarged glands associated with large necrotic areas, with or without dot-like calcification. When the contours of the adrenals were preserved, the diagnosis of infectious disease could be made with increased confidence. Tuberculous adrenalitis should not be excluded when the enlarged adrenal glands appear mass-liking. CT study of the morphological changes of adrenal glands on patients with Addison's disease might help to define the etiology of the disease and contribute to treatment planning.

Nitric oxide and soman poisoning

AIM

To examine whether nitric-oxide (NO) is involved in the toxicity of soman.

METHODS

With pretreatments of icv L-arginine (Arg, the substrate of nitric-oxide synthase NOS), NG-nitro-L-arginine methyl ester (NAME, the inhibitor of NOS), the latency of seizure, and the mortality of mice induced by soman poisoning were examined. The activities of brain NOS in soman-intoxicated mice were measured.

RESULTS

In case of Arg pretreatments, the latency decreased (P < 0.05) from (5.2 +/- 1.8) min (control) to (4.3 +/- 0.8) min (Arg 160 nmol), and the mortality increased (P < 0.05) from 50% (control) to 81% (Arg 160 nmol). In case of NAME pretreatment, the latency increased (P < 0.01) from (4.0 +/- 1.1) min (control) to (14.5 +/- 5.0) min (NAME 2.20 mumol), and the mortality decreased (P < 0.05) from 87% (control) to 50% (NAME 2.20 mumol). The toxicity of soman in mice was enhanced by Arg and reduced by NAME all in a dose-dependent fashion. NAME antagonized the enhancement of soman poisoning by Arg. Intoxication of mice with soman increased the NOS activity in cerebrum, cerebellum, and hippocampus from 100% to 104% (P < 0.05), 115% (P < 0.01), and 111% (P < 0.01), respectively.

CONCLUSION

The onset of seizure and death of mice induced by soman poisoning are related to the NO messenger system.

Primary ureteral carcinoma. Report of 15 cases and comparison of the effectiveness of diagnostic methods

Fifteen cases of primary urothelial carcinomas of the ureter are reported (14 transitional cell carcinoma and 1 mixed transitional cell carcinoma and squamous cell carcinoma). There was a clear male predominance (11/4); the peak incidence was in the sixth decade. Most tumors originated from the distal third of the ureter. Multicentricity and high recurrence rate after partial ureterectomy were noted. The clinical signs were hematuria and flank pain. Urine cytology and IVU were diagnostic in a limited number of cases. Retrograde pyelography was very helpful. CT showed to be the image modality of choice for diagnosis and preoperative staging.

Vascular classification for small intestinal duplications: experience with 80 cases

The records of 80 patients with small intestinal duplication who presented to the department of pediatric surgery, Beijing Children's Hospital during a 25-year period were reviewed. According to the pattern in relation of the vascular supplies to the duplication and involved bowel, the duplications were classified into two types: parallel type (type I) and intramesenteric type (type II). In type I, the duplication was on the border of one leaf of mesentery and the straight artery of the duplication separated from the straight artery to the bowel. In type II, the duplication located in between the both leaves of the mesentery and the straight arteries passed over the both surfaces of the duplication to reach the bowel. It was found that of 83 duplications in 80 patients, 62 cases (75.4%) belonged to type I, and 21 (24.6%) belonged to type II. Surprisingly, 91.6% patients with type II associated with thoracic vertebral defects, whereas only 5.8% in type II had such defects. Results of this study suggest that the duplication of small intestines have relatively independent vascular supplies and could be resected without the adjacent bowel.

Identification of genes expressed in human CD34(+) hematopoietic stem/progenitor cells by expressed sequence tags and efficient full-length cDNA cloning

Hematopoietic stem/progenitor cells (HSPCs) possess the potentials of self-renewal, proliferation, and differentiation toward different lineages of blood cells. These cells not only play a primordial role in hematopoietic development but also have important clinical application. Characterization of the gene expression profile in CD34(+) HSPCs may lead to a better understanding of the regulation of normal and pathological hematopoiesis. In the present work, genes expressed in human umbilical cord blood CD34(+) cells were catalogued by partially sequencing a large amount of cDNA clones [or expressed sequence tags (ESTs)] and analyzing these sequences with the tools of bioinformatics. Among 9,866 ESTs thus obtained, 4,697 (47.6%) showed identity to known genes in the GenBank database, 2, 603 (26.4%) matched to the ESTs previously deposited in a public domain database, 1,415 (14.3%) were previously undescribed ESTs, and the remaining 1,151 (11.7%) were mitochondrial DNA, ribosomal RNA, or repetitive (Alu or L1) sequences. Integration of ESTs of known genes generated a profile including 855 genes that could be divided into different categories according to their functions. Some (8.2%) of the genes in this profile were considered related to early hematopoiesis. The possible function of ESTs corresponding to so far unknown genes were approached by means of homology and functional motif searches. Moreover, attempts were made to generate libraries enriched for full-length cDNAs, to better explore the genes in HSPCs. Nearly 60% of the cDNA clones of mRNA under 2 kb in our libraries had 5' ends upstream of the first ATG codon of the ORF. With this satisfactory result, we have developed an efficient working system that allowed fast sequencing of 32 full-length cDNAs, 16 of them being mapped to the chromosomes with radiation hybrid panels. This work may lay a basis for the further research on the molecular network of hematopoietic regulation.

Reconstitution of beta-adrenergic modulation of large conductance, calcium-activated potassium (maxi-K) channels in Xenopus oocytes. Identification of the camp-dependent protein kinase phosphorylation site

The human large conductance, calcium-activated potassium (maxi-K) channel (alpha and beta subunits) and beta2-adrenergic receptor genes were coexpressed in Xenopus oocytes in order to study the mechanism of beta-adrenergic modulation of channel function. Isoproterenol and forskolin increased maxi-K potassium channel currents in voltage-clamped oocytes expressing the receptor and both channel subunits by 33 +/- 5% and 35 +/- 8%, respectively, without affecting current activation or inactivation. The percentage of stimulation by isoproterenol and forskolin was not different in oocytes coexpressing the alpha and beta subunits versus those expressing the only the alpha subunit, suggesting that the alpha subunit is the target for regulation. The stimulatory effect of isoproterenol was almost completely blocked by intracellular injection of the cyclic AMP dependent protein kinase (cAMP-PK) regulatory subunit, whereas injection of a cyclic GMP dependent protein kinase inhibitory peptide had little effect, indicating that cellular coupling of beta2-adrenergic receptors to maxi-K channels involves endogenous cAMP-PK. Mutation of one of several potential consensus cAMP-PK phosphorylation sites (serine 869) on the alpha subunit almost completely inhibited beta-adrenergic receptor/channel stimulatory coupling, whereas forskolin still stimulated currents moderately (16 +/- 4%). These data demonstrate that physiological coupling between beta2 receptors and maxi-K channels occurs by the cAMP-PK mediated phosphorylation of serine 869 on the alpha subunit on the channel.

Hearing impairment among young Chinese in an urban area

To evaluate hearing levels among young Chinese in an urban area, audiometry was carried out in Jinan city, Shandong Province, China. The subjects were 442 healthy school children and students ranging in age from 6-19 y. All subjects were asked to complete a brief questionnaire on otological symptoms, personal histories and use of noisy playthings. Audiometric threshold testing was performed at the audiometric frequencies of 0.5, 1, 2, 4 and 8 kHz. Logistic regression analysis was used to analyse the items of personal histories related to hearing impairment. Forty-five subjects (10% of the subjects) were classified as abnormal. Nineteen ears of the abnormal subjects showed 4 kHz-dip and 38 ears showed high-frequency hearing impairment. Lower prevalence of hearing impairment was found when compared with young Chinese in a rural area (20%). The logistic regression analysis showed that head trauma may be the cause of hearing impairment among young Chinese in urban areas. Otological examinations for all children sustaining head trauma are recommended.

The effect of radiographic contrast media on human vascular smooth muscle cells

The relation between intravascular radiographic contrast media (RCM) and myointimal hyperplasia after percutaneous transluminal angioplasty is not known. We have investigated the cytotoxic effects of RCM on human vascular smooth muscle cells (VSMCs) and their effect on the growth of these cells. The cytotoxic effects of RCM were studied using human VSMCs. The cells after being grown to confluency were exposed for 60 min to 250 mgI ml-1 of diatrizoate, ioxaglate, iopromide, iotrolan and saturated mannitol solutions. The control group was treated with only 15% fetal calf serum (FCS) containing medium. The viability of the cells was examined using the trypan blue exclusion test. The effect of RCM on growth was assessed by exposing the VSMCs after growth arrest, for either 15 or 60 min to 250 mgI ml-1 of diatrozoate, ioxaglate, iopromide, iotrolan and saturated mannitol solution. There was no significant change in the viability of the VSMCs after 60 min exposure to iopromide, iotrolan, saturated mannitol solution, and after 15 min exposure to diatrizoate or ioxaglate. After exposure to diatrizoate or ioxaglate for 60 min, 16.5 +/- 2.2% or 9.2 +/- 2.6% dead cells were found, respectively (p < 0.05 versus control). In the growth assay of VSMCs, diatrizoate, ioxaglate and saturated mannitol solutions reduced the growth rate (p < 0.05 versus control). No significant change was observed with iopromide and iotrolan. In conclusion, ionic RCM have cytotoxic and cytostatic effects on VSMCs while non-ionic media have no effects. There is no direct stimulatory effect of contrast media on the growth of VSMCs. The cytotoxic and cytostatic effects of contrast media seems to be both osmolality and chemotoxicity dependent. Low osmolar non-ionic RCM are not likely to contribute to the mechanisms responsible for myointimal hyperplasia after angioplasty.

Vac8p, a vacuolar protein with armadillo repeats, functions in both vacuole inheritance and protein targeting from the cytoplasm to vacuole

During each cell cycle, the yeast vacuole actively partitions between mother and daughter cells. This process requires actin, profilin, an unconventional myosin (Myo2p), and Vac8p. A mutant yeast strain, vac8, is defective in vacuole inheritance, specifically, in early vacuole migration. Vac8p is a 64-kD protein found on the vacuole membrane, a site consistent with its role in vacuole inheritance. Both myristoylation and palmitoylation are required for complete Vac8p localization. Interestingly, whereas myristoylation of Vac8p is not required for vacuole inheritance, palmitoylation is essential. Thus, palmitoylation appears to play a more direct role in vacuole inheritance. Most of the VAC8 sequence encodes 11 armadillo (Arm) repeats. Arm repeats are thought to mediate protein-protein interactions, and many Arm proteins have multiple functions. This is also true for Vac8p. In addition to its role in early vacuole inheritance, Vac8p is required to target aminopeptidase I from the cytoplasm to the vacuole. Mutant analysis demonstrates that Vac8p functions separately in these two processes. Vac8p cosediments with actin filaments. Vac8p is related to beta-catenin and plakoglobin, which connect a specific region of the plasma membrane to the actin cytoskeleton. In analogy, Vac8p may link the vacuole to actin during vacuole partitioning.

Endbulb synapses in the anteroventral cochlear nucleus express a specific subset of AMPA-type glutamate receptor subunits

The anteroventral cochlear nucleus (AVCN) acts as the first relay center in the conduction of auditory information from the ear to the brain, and it probably performs a crucial role in sound localization. Auditory nerve input to the principal neurons of the AVCN, the spherical bushy cells, appears to be mediated by an excitatory amino acid such as glutamate, which acts at a specialized, large synaptic ending called an endbulb of Held. Presumably, endbulb synapses contain some specific combination of glutamate receptors to facilitate rapid neurotransmission of auditory signals. AMPA glutamate receptor composition at the endbulb synapses was examined with both light and electron microscope immunocytochemistry. Electron microscope localization of AMPA receptors was examined with two techniques, preembedding immunoperoxidase and postembedding immunogold, which provide maximum sensitivity and greatest accuracy, respectively. Dense and frequent labeling was seen with the AMPA receptor subunit antibodies GluR2/3 and GluR4, which were colocalized at the endbulb synapses. In contrast, immunolabeling with antibody to GluR2 was low. These data indicate that the major glutamate receptor at this synapse is an AMPA receptor made up mainly of GluR3 and GluR4 subunits. Receptors composed of these subunits display properties, such as calcium permeability and rapid desensitization, that facilitate their specialized functions in auditory information processing.

1-Methyl-3-pyrrolines and 2-methylisoindolines: new classes of cyclic tertiary amine monoamine oxidase B substrates

Both 1-methyl-3-pyrrolines and 2-methylisoindolines are substrates for MAO-B with Vmax/Km values ranging from 200 to 2000 min-1 mM-1 at 37 degrees C. These compounds represent new classes of cyclic tertiary amine substrates for this flavoenzyme. The only other known cyclic amines that are MAO-B substrates are 1,4-disubstituted 1,2,3,6-tetrahydropyridinyl derivatives. The presence of an allylic (benzylic) amino functionality in all of these compounds may be linked to their substrate properties since related piperidinyl and pyrrolidinyl analogs are stable in the presence of MAO-B. This paper discusses energetic and geometric features of these compounds in relationship to their substrate properties and in anticipation of their utility to probe the active site of this flavoenzyme.

Peripheral versus central potencies of N-type voltage-sensitive calcium channel blockers

The ability of a series of synthetic analogues of omega-conopeptides MVIIA (SNX-111) and TVIA (SNX-185) to prevent electrically-evoked norepinephrine release from rat tail artery and hippocampal slice preparations was determined in an effort to identify voltage-sensitive calcium channel (VSCC) blockers that selectively target N-type VSCCs in central nervous system tissue. Electrical field stimulation (3 Hz, 1 ms in duration. 80 V for 1 min) caused a high and consistent tritium outflow from rat tail artery and hippocampal slice preparations preloaded with [3H]-norepinephrine. All conopeptides, chosen for their selective affinities for high-affinity SNX-111 binding sites (i.e., N-type VSCCs) over high-affinity omega-conopeptides MVIIC (SNX-230) binding sites (i.e., P/Q-type VSCCs), produced a concentration-dependent inhibition of calcium dependent electrically-evoked tritium outflow from both tail arteries and hippocampal slices: IC50s ranged from 1.2 nM to 1.2 microM. Blocking potencies (IC50s) in the tail artery assay were significantly correlated with those measured in the hippocampal slice preparation (r = 0.91, P = 0.00000012). There was a significant correlation between IC50s for blockade of hippocampal norepinephrine release and the inhibition of high-affinity [125I]-SNX-I11 binding in rat brain synaptosomes (r = 0.76, P = 0.00028). Blockade of hippocampal norepinephrine release was not significantly correlated with the inhibition of high-affinity SNX-230 binding (r = 0.46, P = 0.056). Maximum inhibition of tritium outflow in the tail artery assay was 22+/-1.4% of control, approximating the value (20.9+/-16.0% of control) obtained in the absence of extracellular Ca2+. In contrast, the maximum inhibition of tritium release from hippocampal slices was 36.8+/-2.5% of control (P < 0.05, compared to that of the tail artery assay). These results suggest that (1) N-type VSCCs alone mediate low frequency electrical stimulation-evoked neurotransmitter release from peripheral sympathetic efferents (tail artery) while both N-type and non-N type(s) mediate neurotransmitter release from CNS neurons (hippocampus); and (2) analogues of omega-conopeptides MVIIA and TVIA do not differentiate between N-type VSCCs mediating norepinephrine release from central and peripheral neural tissues.

The human P2X4 receptor gene is alternatively spliced

ATP acts as a fast excitatory neurotransmitter by binding to a large family of membrane proteins, P2X receptors, that have been shown to be ligand-gated, non-selective cation channels. We report the cloning of a full-length and alternatively spliced form of the human P2X4 gene. Clones were identified from a human stomach cDNA library using a rat P2X4 probe. Nucleotide sequence analysis of positive clones identified the full-length human P2X4 cDNA, which codes for a 388-residue protein that is highly homologous (82%) to the rat gene, and an alternatively spliced cDNA. In the alternatively spliced cDNA, the 5'-untranslated region and the first 90 amino acids in the coding region of full-length human P2X4 are replaced by a 35 amino acid coding sequence that is highly homologous with a region of chaperonin proteins in the hsp-90 family. The open reading frames of the full-length and splice variant clones were confirmed by in vitro translation. Northern analysis indicated expression of the full-length P2X4 message in numerous human tissues including smooth muscle, heart, and skeletal muscles. Alternatively spliced RNAs were identified in smooth muscle and brain by RT-PCR and confirmed by RNAse protection assays using a 710 bp anti-sense RNA probe that spanned the alternatively spliced and native P2X4 regions. Injection of full-length, but not alternatively spliced, cRNA into Xenopus oocytes resulted in the expression of ATP gated non-selective cation currents.

Inactivation of calcium-activated chloride channels in smooth muscle by calcium/calmodulin-dependent protein kinase

To determine the mechanisms responsible for the termination of Ca2+-activated Cl- currents (ICl(Ca)), simultaneous measurements of whole cell currents and intracellular Ca2+ concentration ([Ca2+]i) were made in equine tracheal myocytes. In nondialyzed cells, or cells dialyzed with 1 mM ATP, ICl(Ca) decayed before the [Ca2+]i decline, whereas the calcium-activated potassium current decayed at the same rate as [Ca2+]i. Substitution of AMP-PNP or ADP for ATP markedly prolonged the decay of ICl(Ca), resulting in a rate of current decay similar to that of the fall in [Ca2+]i. In the presence of ATP, dialysis of the calmodulin antagonist W7, the Ca2+/calmodulin-dependent kinase II (CaMKII) inhibitor KN93, or a CaMKII-specific peptide inhibitor the rate of ICl(Ca) decay was slowed and matched the [Ca2+]i decline, whereas H7, a nonspecific kinase inhibitor with low affinity for CaMKII, was without effect. When a sustained increase in [Ca2+]i was produced in ATP dialyzed cells, the current decayed completely, whereas in cells loaded with 5'-adenylylimidodiphosphate (AMP-PNP), KN93, or the CaMKII inhibitory peptide, ICl(Ca) did not decay. Slowly decaying currents were repeatedly evoked in ADP- or AMP-PNP-loaded cells, but dialysis of adenosine 5'-O-(3-thiotriphosphate) or okadaic acid resulted in a smaller initial ICl(Ca), and little or no current (despite a normal [Ca2+]i transient) with a second stimulation. These data indicate that CaMKII phosphorylation results in the inactivation of calcium-activated chloride channels, and that transition from the inactivated state to the closed state requires protein dephosphorylation.

Conservation approach to duplication of the small bowel

BACKGROUND/PURPOSE

Intestinal duplication and adjacent small bowel share a single mesentery with straight arteries from the arcade supplying the normal bowel or supplying the duplication. The usual surgical management is resection of the duplication and the adjacent bowel with end to end anastomosis of the remaining bowel. The aim of this study was to conduct an experimental study of blood supply to the bowel and consequences of ligation of the straight arteries to one side of the bowel, and attempt preservation of all normal bowel in patients who have duplication.

METHODS

The study was carried out on 25 New Zealand white rabbits. The intestinal blood supply of three groups of rabbits (control, acute, and chronic) have been studied by perfusion, microdissection and stereoscopic microscopic examination, and scanning electron microscopy after impregnation with gold, after ligation of the straight arteries to one side of the intestine. From 1992 to 1996, 14 patients who had duplication of the bowel were treated by resection of duplication and conservation of bowel. They have had follow-up for up 4 years. Barium studies have been performed.

RESULTS

In the animal studies, the bowel was viable and functioning normally in all animals but numerous adhesions developed. The results presented show no impairment in bowel function in human studies.

CONCLUSION

Ligation of the straight arteries to the duplication with resection of only the duplication is a satisfactory approach to conservation of bowel in patients who have duplication.

Effects of radiographic contrast media on the tension of isolated small pulmonary arteries

The aim of the study was to establish the direct effects of radiographic contrast media (RCM) on the tension of isolated small pulmonary arteries and to investigate any mediation by nitric oxide (NO) and endothelin (ET). Small pulmonary arteries (0.3-0.6 mm in diameter) from male Wistar rats were mounted in a Cambustion vessel myograph and vessel wall tension recorded. The effects of 10, 20, 40, 80, 150, 200 and 250 mgl mI-1 of diatrizoate, ioxaglate, iopromide and iotrolan and their mannitol osmolar control from basal condition, and when the vessels were preconstricted with prostaglandin F2 alpha (PGF2 alpha) either submaximally (10 microM) or maximally (100 microM), were studied. The constrictor response to diatrizoate (40 mgI ml-1) was tested in the presence of non-selective endothelin receptor antagonist (10 microM SB209670). The dilator response to ioxaglate (80 mgI ml-1) was tested in the presence of L-nitroarginine methyl ester (L-NAME, 100 microM). All RCM caused biphasic changes in tension, a small transient fall (dilatation) followed by a sustained rise (constriction). Mannitol caused constriction only. The potency order of constrictions at 10-40 mgI ml-1 was diatrizoate > iopromide > ioxaglate > iotrolan. When the vessels were preconstricted with PGF2 alpha, RCM caused predominantly dilatation; ioxaglate produced the largest effect (-42.1 +/- 3.1%, n = 12). Mannitol caused constriction only. SB209607 had no effect on the constrictor effect of diatrizoate [41.9 +/- 2.3 alone, 42.1 +/- 2.7 with SB209670, n = 10]. L-NAME had no effect on the dilator response to ioxaglate [-38.2 +/- 1.6 alone, -43.6 +/- 2.2 with L-NAME, n = 8]. It is tempting to postulate that dimeric RCM may cause the least changes in the pulmonary circulation during angiography.

Biological activation of N(G)-nitro-D-arginine by kidney homogenate

N(G)-nitro-L-arginine (L-NNA) and D-NNA have been shown to inhibit endothelium-dependent relaxation. This study examined if the inhibitory effect of L-NNA or D-NNA on relaxation is increased following incubation of the drug with the supernatant of tissue homogenates. Acetylcholine (ACh) caused concentration-dependent relaxation of pre-constricted rat aortic rings with maximum relaxation of 95%. Maximum relaxations to ACh were reduced to 71 and 37% in the presence of D-NNA (40 microM) and L-NNA (1 microM), respectively. Relaxation to ACh was further reduced to 18% in the presence of D-NNA that was incubated for 1 h with the supernatant of kidney homogenate, but unaffected by D-NNA incubated with the supernatant of trichloroacetic acid-denatured kidney homogenate. Incubation of L-NNA (1 microM) with either kidney supernatant or denatured kidney supernatant for 1 h did not affect its inhibitory effect on ACh-induced relaxation. Neither 1 h's incubation with plasma, or supernatants of liver, lungs or aorta homogenates affected the inhibitory action of D-NNA (40 or 120 microM) on ACh-induced relaxation. After D-NNA was incubated in kidney supernatant, its inhibitory effect on ACh-induced relaxation of the aorta was abolished by pretreatment of the aorta with L-arginine (L-Arg) but not D-Arg suggesting involvement of the L-Arg pathway. The results suggest that D-NNA is converted by the kidney to a compound that acts similar to L-NNA. There appears to be little conversion of L-NNA to D-NNA.

Sexual dimorphism in regional blood flow responses to vasopressin in conscious rats

The greater pressor response to vasopressin in male than in nonestrous female rats results from a greater increase in total peripheral resistance in males. The present study was performed to identify the vascular beds that contribute to this difference. Mean arterial blood pressure (MABP) and changes in blood flow in the mesenteric and renal arteries and terminal aorta were measured in conscious male and nonestrous female rats 3 h after surgery. Graded intravenous infusions of vasopressin induced greater increases in MABP and mesenteric vascular resistance and a greater decrease in mesenteric blood flow in males. Vasopressin also increased renal vascular resistance to a greater extent in males. Because renal blood flow remained unchanged, this difference may be due to autoregulation. The vasopressin-induced reduction in blood flow and increased resistance in the hindquarters were moderate and did not differ between sexes. Thus the greater vasoconstrictor response to vasopressin in the mesenteric vascular bed of male than nonestrous females contributed importantly to the sexually dimorphic pressor response to vasopressin in these experiments.

Glutamate receptor subunit 2-selective antibody shows a differential distribution of calcium-impermeable AMPA receptors among populations of neurons

Alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors are the major excitatory neurotransmitter receptors of the central nervous system. AMPA receptor complexes that contain the AMPA-type glutamate receptor subunit 2 (GluR2) are responsible for the low calcium permeability typical of most AMPA receptors, and the absence of GluR2 may be a key factor in neurotoxicity. A polyclonal antibody was produced to a 16 amino acid peptide near the C-terminus of GluR2 and was affinity-purified in a three-step procedure. The antibody did not recognize other AMPA subunits in transfected cells with the use of either Western blots or immunocytochemistry. This highly specific GluR2 antibody was used to provide a specific morphological study of GluR2 protein distribution in neurons and synapses of the rat. GluR2 is prevalent in most principal neurons throughout the telencephalon. Neurons with few or no GluR2 subunits include two major types: 1) some populations of interneurons of the telencephalon and of some other areas and 2) many populations of principal neurons in the brainstem and spinal cord. Immunofluorescence showed that GluR2 immunolabeling was widespread, including in dendrites and puncta, in the hippocampus and neocortex. Where they were present, GluR2 subunits colocalized with other AMPA receptor subunits in individual neurons. Electron microscopy of the hippocampus showed GluR2-bearing, calcium-impermeable AMPA receptors postsynaptic to dendrite synapses of forebrain principal neurons. In addition, electron microscopy of the neocortex showed significant staining in postsynaptic profiles. Electron microscopy of the cerebellum revealed the presence of GluR2 subunits in the postsynaptic profiles of many parallel fiber/Purkinje cell spine synapses, whereas electron microscopy of the spinal cord showed substantial staining in the postsynaptic profiles of dorsal horn synapses, but not in ventral horn synapses. Both ultrastructural and immunofluorescence data showed that calcium-impermeable AMPA receptors are widespread in dendrite arborizations.

Ionic mechanism responsible for prolongation of cardiac action-potential duration by berberine

This study was designed to investigate the effects of berberine on membrane currents forming the repolarization phase of action potentials in isolated guinea pig ventricular myocytes by using the patch-clamp technique. Application of berberine (3-30 microM) to the current-clamped myocytes produced a significant prolongation of action-potential duration (APD), which was concentration dependent. However, this agent (3-30 microM) did not affect the resting potential and action-potential amplitude. The prolongation of APD caused by berberine was not attenuated by tetrodotoxin (TTX, 10 microM), and TTX (10 microM) failed to shorten APD in cells pretreated with 30 microM berberine. Under the voltage-clamp conditions, berberine (3-30 microM) inhibited the delayed rectifier K+ currents (I(K)). Under conditions in which the rapidly activating components (I(Kr)) and slowly activating component (I(Ks)) were dissected out, berberine was shown to block I(Ks) without affecting I(Kr). Application of berberine (3-30 microM) increased the Na+-Ca2+ exchange currents, which were completely abolished by 5 mM NiCl. The L-type Ca2+ currents (I(Ca)) also were increased by 3-30 microM berberine, but the threshold potential, the potential at which I(Ca) was maximal, and the apparent reversal potential remained unchanged. Berberine at either 3 or 30 microM did not affect the inward rectifier K+ currents. This study suggests that the prolongation of cardiac repolarization by berberine is mainly caused by the inhibition of I(Ks) and increase of I(Ca).