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M Wahl

Publications and source records attributed to M Wahl.

At least 37 records · Page 2Linked to original sources
PubMed2000

A novel brain trauma model in the mouse: effects of dexamethasone treatment.

We describe a novel methodological approach for inducing cold lesion in the mouse as a model of human cortical contusion trauma. To validate its reproducibility and reliability, dexamethasone (Dxm) was repeatedly applied to demonstrate possible antioedematous drug effects. Following the induction of anaesthesia with halothane, the dura was exposed via trephination. Using a micromanipulator a pre-cooled (-78 degrees C) copper cylinder, 3 mm in diameter, was pressed down to a depth of 1 mm onto the dura for 30 s under microscopic control. The body temperature was held constant at 37 degrees C throughout the procedure. Blood pressure (BP), measured by a modified photosensor-monitored tail-cuff method, and acid-base status were not significantly different when analysed before and after cold lesion and prior to sacrifice. However, there was a marginal mixed respiratory and metabolic acidosis. The antioedematous action of Dxm was studied in four standard pre-and post-treatment paradigms: 2x0.5 mg/kg (II), 2x12.5 mg/kg (III) and 4x6.25 mg/kg (IV: 3x pre-, 1x post-treatment: V: 1x pre-, 3x post-treatment). Physiological saline injections served as controls. High doses of Dxm (III-V) significantly attenuated the cold-lesion-induced loss of body mass. Dxm treatment also resulted in a reduction of brain water content (III; P<0.05), and brain swelling (IV; P<0.05) in the lesioned hemisphere, relative to controls. In conclusion, we have characterized a novel cold lesion model in the mouse to mimic traumatic brain injury and the beneficial effect of Dxm treatment on the extent of brain oedema.

Acid-Base Equilibrium↗
PubMed2000

Medical outcome of cocaine bodystuffers.

To describe the clinical course of cocaine "bodystuffers" presenting to regional emergency departments, a descriptive retrospective analysis was performed on all cases of cocaine bodystuffers received by a metropolitan poison control center and associated toxicology service from January 1993 to May 1994. We identified 46 cases of patients classified as bodystuffers. Of these, 34 patients (74%) remained asymptomatic. Eight patients (18%) had mild symptoms including hypertension and tachycardia that resolved with no treatment beyond decontamination or benzodiazepines (one patient). Two patients (4%) had moderate symptoms including agitation and fever that resolved with no treatment beyond decontamination or benzodiazepines (one patient). Two patients (4%) had severe symptoms including seizure and cardiac dysrhythmia. Both died. Radiographs of the abdomen were negative for foreign body in all 23 examinations performed. Mild cocaine intoxication is common in cocaine bodystuffers. Severe intoxication can occur, resulting in death. Abdominal radiographs are not of value for stuffers ingesting cellophane-wrapped packets. More experience is needed to determine the length of intensive care monitoring that these patients require.

Antidotes↗
PubMed2000

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Journal Article↗
PubMed2000

Effect of estradiol on insulin secreting INS-1 cells overexpressing estrogen receptors.

BACKGROUND: Estrogen has been shown to have profound effects on insulin and glucose metabolism in vivo. Indeed, estrogens were recently shown to modulate ion channel and secretory activities in endocrine cells. DESIGN AND METHODS: To investigate whether estrogenic influences are caused by direct effects on pancreatic beta-cells, we equipped INS-1 insulinoma cells with estrogen receptors and monitored insulin content and Ca(2+) fluxes as well as basal and stimulated insulin secretion upon different stimuli including glucose, the Ca(2+) ionophore ionomycin, the Ca(2+) channel agonist BayK8644, the protein kinase C activator TPA, and the adenylate cyclase activator forskolin. RESULTS AND CONCLUSION: Our data reveal that estradiol has no significant direct effect on proliferation rate, insulin content, basal and stimulated insulin output as well as Ca(2+) fluxes of insulin secreting cells in vitro, indicating that in vivo responses to estrogen on insulin and glucose metabolism result from indirect betacytotropic effects.

Calcium↗
PubMed1999

Crystal structure of an RNA duplex r(G GCGC CC)2 with non-adjacent G*U base pairs.

The crystal structure of a self-complementary RNA duplex r(GGGCGCUCC)2with non-adjacent G*U and U*G wobble pairs separated by four Watson-Crick base pairs has been determined to 2.5 A resolution. Crystals belong to the space group R3; a = 33.09 A,alpha = 87.30 degrees with a pseudodyad related duplex in the asymmetric unit. The structure was refined to a final Rworkof 17.5% and Rfreeof 24.0%. The duplexes stack head-to-tail forming infinite columns with virtually no twist at the junction steps. The 3'-terminal cytosine nucleosides are disordered and there are no electron densities, but the 3' penultimate phosphates are observed. As expected, the wobble pairs are displaced with guanine towards the minor groove and uracil towards the major groove. The largest twist angles (37.70 and 40.57 degrees ) are at steps G1*C17/G2*U16 and U7*G11/C8*G10, while the smallest twist angles (28.24 and 27.27 degrees ) are at G2*U16/G3*C15 and C6*G12/U7*G11 and conform to the pseudo-dyad symmetry of the duplex. The molecule has two unequal kinks (17 and 11 degrees ) at the wobble sites and a third kink at the central G5 site which may be attributed to trans alpha (O5'-P), trans gamma (C4'-C5') backbone conformations. The 2'-hydroxyl groups in the minor groove form inter-column hydrogen bonding, either directly or through water molecules.

Base Pairing↗
PubMed1999

Temporal profile of expression and cellular localization of inducible nitric oxide synthase, interleukin-1beta and interleukin converting enzyme after cryogenic lesion of the rat parietal cortex.

We used in situ hybridization, RT PCR and immunohistochemistry to study the time course of expression and the cellular localization of inducible nitric oxide synthase (iNOS) and interleukin-1beta (IL-1beta) during the first 7 days after induction of a standardized cryogenic lesion on the right parietal cortex in male rats. Cryogenic lesion induced iNOS mRNA in the lesioned hemisphere after 6 to 72 h with a maximum (15+/-2 cells/mm2, n=4, p<0.01 vs. sham) at 24 h. Microglia, invading monocytes and granulocytes in and around the lesion expressed iNOS immunoreactivity starting at 12 h and peaking (29+/-10 cells/mm2, n=4, p<0.05 vs. sham) at 24 h after lesion. Induction of IL-1beta mRNA expression was immediate with a peak (9+/-1 cells/mm2, n=4, p<0.01 vs. sham) at 24 h after cryogenic lesion. The number of round cells with IL-1beta immunoreactivity around the lesion was maximal (8+/-2 cells/0.1 mm2, n=3, p<0.01 vs. sham) at 24 h. A weak astrocytic expression of IL-1beta-immunoreactivity was seen in sham animal brains. Astrocytic IL-1beta-expression was significantly increased in the lesion hemisphere and both hippocampi. Interleukin converting enzyme (ICE) was expressed in astrocytes and microglia around the lesion 6 h after injury. The number of ICE immunoreactive cells (8+/-2 cells/0. 1 mm2, n=3, p<0.05 vs. sham) peaked at 72 h after lesion. Neuronal expression of ICE and IL-1beta was seen in the lesion periphery 72 h and 7 days after injury. At this time, morphological features of apoptosis were evident in cells in the lesion periphery. The data indicate an early activation of microglia and monocyte invasion into the lesion hemisphere leading to multicellular expression of iNOS, ICE, and IL-1beta. These events may contribute to the expansion of neuronal damage after brain injury.

Animals↗
PubMed1999

Mediators of cerebral edema.

The blood-brain barrier (BBB) which is located in the continuous endothelial lining of cerebral blood vessels rigidly controls exchange of water soluble compounds under physiological conditions. Under pathological conditions such as trauma or ischemia, BBB permeability may increase thus allowing plasma constituents to escape into brain tissue. This "opening" of the BBB may, at least in part, be mediated by massive release of autacoids resulting in vasogenic brain edema. Five criteria have to be fulfilled by an individual autacoid to be considered a mediator candidate of cerebral edema: i) a permeability-enhancing action under physiological conditions, ii) a vasodilatory action, iii) the ability to induce vasogenic brain edema, iv) an increase of concentration in the tissue or interstitial fluid under pathological conditions, and v) a decrease of brain edema by specific interference with the release or action of a given autacoid. Among the mediator candidates considered, bradykinin is the only one to meet all criteria. Histamine, arachidonic acid and free radicals including nitric oxide may also be considered mediators of brain edema, but for each of these compounds evidence is less clear than for bradykinin. Although the concept of mediators inducing brain edema is well established by experimental studies, only a bradykinin receptor antagonist has so far gained entrance into clinical evaluation.

Animals↗
PubMed1999

Can we evaluate the pressure of perihepatic packing? Results of a study on dogs.

The pressure of perihepatic packing can cause organ perfusion disturbances. The problem is to determine the pressure applied during the operative procedure. The objective of this animal study was to assess the perihepatic packing pressure and its effect on the pressure in the inferior vena cava (IVC). In order to assess the pressure in the IVC a catheter was introduced through the femoral vein. A rearranged tourniquet for blood pressure measurement was placed on the dog liver and with various perihepatic pressures the resulting pressures in the IVC were assessed. It was established, that by applying pressure of 30 mm Hg to the liver, the pressure in the IVC did not exceed 10 cm of water. Two clinical cases are reported where the method was shown to be crucial for the management. The first one is related to haemodynamic instability after successful perihepatic packing for grade V injury. In the second case, an otherwise stable patient had significantly elevated pressure in the IVC, which crucially influenced the treatment. The introduction of a catheter into the IVC to monitor the pressure in patients with liver injuries is useful.

Adolescent↗
PubMed1999

Interference of antibody production to hepatitis B surface antigen in a combination hepatitis A/hepatitis B vaccine.

A randomized trial comparing 3 manufacturing consistency lots of a combination hepatitis A/hepatitis B vaccine to each other and to hepatitis A vaccine and hepatitis B vaccine given separately and concurrently was done to evaluate safety, tolerability, and immunogenicity. Healthy volunteers >/=11 years of age were divided into 4 groups. Each of 3 groups received a separate consistency lot of the combination vaccine, and 1 group received separate but concurrent injections of hepatitis A and hepatitis B vaccines. Injections were given at weeks 0 and 24. The combination vaccine was generally well tolerated. The hepatitis A portion of the combination vaccine produced clinically acceptable high seropositivity rates 4 and 52 weeks after the first injection. The hepatitis B portion of the vaccine did not produce clinically acceptable seropositivity rates 4 weeks after the second injection. Lack of antibody production may be attributed, at least in part, to immunologic interference.

Adolescent↗
PubMed1999

Solution structure of the receptor tyrosine kinase EphB2 SAM domain and identification of two distinct homotypic interaction sites.

The sterile alpha motif (SAM) is a protein interaction domain of around 70 amino acids present predominantly in the N- and C-termini of more than 60 diverse proteins that participate in signal transduction and transcriptional repression. SAM domains have been shown to homo- and hetero-oligomerize and to mediate specific protein-protein interactions. A highly conserved subclass of SAM domains is present at the intracellular C-terminus of more than 40 Eph receptor tyrosine kinases that are involved in the control of axonal pathfinding upon ephrin-induced oligomerization and activation in the event of cell-cell contacts. These SAM domains appear to participate in downstream signaling events via interactions with cytosolic proteins. We determined the solution structure of the EphB2 receptor SAM domain and studied its association behavior. The structure consists of five helices forming a compact structure without binding pockets or exposed conserved aromatic residues. Concentration-dependent chemical shift changes of NMR signals reveal two distinct well-separated areas on the domains' surface sensitive to the formation of homotypic oligomers in solution. These findings are supported by analytical ultracentrifugation studies. The conserved Tyr932, which was reported to be essential for the interaction with SH2 domains after phosphorylation, is buried in the hydrophobic core of the structure. The weak capability of the isolated EphB2 receptor SAM domain to form oligomers is supposed to be relevant in vivo when the driving force of ligand binding induces receptor oligomerization. A formation of SAM tetramers is thought to provide an appropriate contact area for the binding of a low-molecular-weight phosphotyrosine phosphatase and to initiate further downstream responses.

Amino Acid Motifs↗
PubMed1999

Effects of bradykinin in the cerebral circulation.

All components of an intracerebral kallikrein-kinin system have been described. Thus, bradykinin (BK) acting from the parenchymal side as well as from the blood side may influence cerebral microcirculation. BK is a potent dilator of extra- and intraparenchymal cerebral arteries when acting from the perivascular side. The vasomotor effect of BK is mediated by B2 receptors which appear to be located at the abluminal membrane of the endothelial cell. Signal transmission from the endothelial to the smooth muscle cell is mediated by NO, prostanoids, free radicals or H2O2 depending on the animal species and on the location of the artery. Selective opening of the blood-brain barrier for small tracers (Na+-fluorescein: MW, 376) has been found in cats during cortical superfusion or intraarterial application of BK. This leakage is mediated by B2 receptors located at the luminal and abluminal membrane of the endothelial cells and probably mediated by an opening of tight junctions. Formation of brain edema has been found after ventriculo-cisternal perfusion or interstitial infusion of BK. This can be explained by increase of vascular permeability and cerebral blood flow due to arterial dilatation thus enhancing driving forces for the extravasation. An increase of the BK concentration in the interstitial space of the brain up to concentrations which induce extravasation, dilatation and edema formation has been found under several pathological conditions. Thus, BK may be involved in edema and necrosis formation after cold lesion, concussive brain injury, traumatic spinal cord and ischemic brain injury.

Animals↗
PubMed1999

Selective inhibition of neuronal nitric oxide synthase fails to alter the resting tension and the relaxant effect of bradykinin in isolated rat middle cerebral arteries.

The role of the neuronal isoform of the nitric oxide (NO) synthase (nNOS) in the regulation of the cerebrovascular tone was studied in vitro. Selective inhibition of nNOS by 7-nitro indazole monosodium salt (7-NINA) failed to alter the resting tension and the relaxant effect of bradykinin in isolated rat middle cerebral arteries. These results indicate that 1./ 7-NINA is selective for nNOS and 2./ cerebrovascular nNOS is involved neither in the resting NO production nor in the mediation of the relaxant effect of bradykinin. Therefore, nNOS-derived NO that contributes to the maintenance of the resting cerebral blood flow in vivo appears to be released from neurons and/or glial cells.

Animals↗
PubMed1998

Prostate stem cell antigen: a cell surface marker overexpressed in prostate cancer.

The identification of cell surface antigens is critical to the development of new diagnostic and therapeutic modalities for the management of prostate cancer. Prostate stem cell antigen (PSCA) is a prostate-specific gene with 30% homology to stem cell antigen 2, a member of the Thy-1/Ly-6 family of glycosylphosphatidylinositol (GPI)-anchored cell surface antigens. PSCA encodes a 123-aa protein with an amino-terminal signal sequence, a carboxyl-terminal GPI-anchoring sequence, and multiple N-glycosylation sites. PSCA mRNA expression is prostate-specific in normal male tissues and is highly up-regulated in both androgen-dependent and -independent prostate cancer xenografts. In situ mRNA analysis localizes PSCA expression in normal prostate to the basal cell epithelium, the putative stem cell compartment of the prostate. There is moderate to strong PSCA expression in 111 of 126 (88%) prostate cancer specimens examined by in situ analysis, including high-grade prostatic intraepithelial neoplasia and androgen-dependent and androgen-independent tumors. Flow cytometric analysis demonstrates that PSCA is expressed predominantly on the cell surface and is anchored by a GPI linkage. Fluorescent in situ hybridization analysis localizes the PSCA gene to chromosome 8q24.2, a region of allelic gain in more than 80% of prostate cancers. A mouse homologue with 70% amino acid identity and similar genomic organization to human PSCA has also been identified. These results support PSCA as a target for prostate cancer diagnosis and therapy.

Amino Acid Sequence↗
PubMed1998

Role of nitric oxide and thromboxane in the maintenance of cerebrovascular tone.

This study investigated the role of thromboxane A2 (TXA2) and neuronal nitric oxide (NO) synthase (nNOS)-derived NO in the maintenance of resting cerebrovascular tone. Rat basilar artery (BA) segments were mounted in myographs to study their isometric tension development. 7-Nitro indazole monosodium salt (7-NINA), a specific inhibitor of nNOS, had no significant effect on the resting tone, whereas the general NOS blocker N(G)-nitro-L-arginine (L-NA) induced strong contraction. The thromboxane (TP) receptor antagonist ICI 192605 induced weak vasodilation, and this effect was significantly enhanced after precontraction of the vessels with uridine-5'-triphosphate (UTP). Incubation of BA segments with ICI 192605 attenuated the contractile effect of UTP. These data indicate that nNOS is not involved in resting cerebrovascular NO production and that basal TXA2 release induces a weak contractile tone in the rat BA. Activation of P2U receptors by UTP appears to stimulate TXA2 release in these vessels.

Animals↗
PubMed1998

Effect of L-arginine on adrenal and renal blood flows during hemorrhage in cats.

Our earlier studies have shown development of endothelial dysfunction in the feline renal artery during hemorrhagic hypotension. Because L-arginine (L-Arg), the precursor of nitric oxide (NO), reportedly improves endothelial function in several pathophysiological states including hypotension, we investigated its possible beneficial effect on the adrenal and renal circulations during hemorrhagic hypotension in anesthetized, ventilated cats. Hypotension (mean arterial pressure 50 mm Hg) significantly increased vascular resistance and decreased blood flow (radiolabeled microspheres) in both adrenal and renal cortices. L-Arg (30 mg/kg bolus, 10 mg/kg/min infusion, i.v.) had no significant hemodynamic effects in normotension but prevented the increase of the vascular resistance and improved blood flow in the adrenal cortex during hypotension. In the kidney, L-Arg also prevented hemorrhage-induced vasoconstriction, although its effect on blood flow did not reach significance. The NO synthase inhibitor N(G)-nitro-L-arginine (30 mg/kg bolus, 1 mg/kg/min infusion, i.v.) increased adrenal and renal vascular resistances to a similar extent as that observed during hypotension. It thus seems that an L-Arg-reversible dysfunction of the endothelial NO-synthesizing pathway contributes to hemorrhage-induced adrenal and renal vasoconstriction.

Adrenal Glands↗