Burst firing of action potentials in central snail neurons elicited by d-amphetamine: effect of anticonvulsants

The effect of anticonvulsants on the burst firing of action potentials in snail central neuron elicited by d-amphetamine was studied in the identified RP4 neuron of the African snail, Achatina fulica Ferussac. Oscillation of membrane potential and burst firing of action potentials were elicited by d-amphetamine in a concentration-dependent manner. Voltage clamped studies revealed that d-amphetamine elicited a negative slope resistance (NSR) in steady-state I-V curve between - 40 and - 10 mV. The burst firing of action potentials was alleviated following extracellular application of phenytoin, but was not affected after ethosuximide, carbamazepine, and valproic acid. The NSR elicited by d-amphetamine was blocked by phenytoin. However, the NSR was not altered if carbamazepine was added. These results suggest that of the four anticonvulsants tested, only phenytoin could alleviate the burst firing of action potentials elicited by d-amphetamine in snail neuron.

Cardioprotective effect of resveratrol, a natural antioxidant derived from grapes

BACKGROUND

The major objective of the present study was to examine the cardioprotective effect of resveratrol, an antioxidant presents in red wines, in the rat after ischemia and ischemia-reperfusion (I-R).

METHODS

The left main coronary artery was occluded for 30 or 5 min followed by a 30-min reperfusion in anesthetized rats. Animals were preinfused with and without resveratrol before occlusion and the severity of ischemia- and I-R-induced arrhythmias and mortality were compared.

RESULTS

Resveratrol pretreatment had no effect on ischemia-induced arrhythmias nor on mortality. In contrast, a dramatic protective effects were observed against I-R-induced arrhythmias and mortality. Resveratrol pretreatment both reduced the incidence and duration of ventricular tachycardia (VT) and ventricular fibrillation (VF). During the same period, resveratrol pretreatment also increased nitric oxide (NO) and decreased lactate dehydrogenase levels in the carotid blood.

CONCLUSIONS

Resveratrol is a potent antiarrhythmic agent with cardioprotective properties in I-R rats. The cardioprotective effects of resveratrol in the I-R rats may be correlated with its antioxidant activity and upregulation of NO production.

Reversal of human immunodeficiency virus type 1-associated hematosuppression by effective antiretroviral therapy

The immunodeficiency of human immunodeficiency virus type 1 (HIV-1) disease may be due to accelerated destruction of mature CD4+ T cells and/or impaired differentiation of progenitors of CD4+ T cells. HIV-1 infection may also inhibit the production of other hematopoietic lineages, by directly or indirectly suppressing the maturation of multilineage and/or lineage-restricted hematopoietic progenitor cells. To test this hypothesis, the effects of durable viral suppression on multilineage hematopoiesis in 66 HIV-1-seropositive patients were evaluated. Administration of effective antiretroviral therapy resulted in an increase in circulating CD4+ T cell counts and statistically significant increases in circulating levels of other hematopoietic lineages, including total white blood cells, lymphocytes, polymorphonuclear leukocytes, and platelets. These results suggest that a significant lesion in untreated HIV-1 disease may lie at the level of cell production from hematopoietic progenitors.

Forecasts using neural network versus Box-Jenkins methodology for ambient air quality monitoring data

This study explores ambient air quality forecasts using the conventional time-series approach and a neural network. Sulfur dioxide and ozone monitoring data collected from two background stations and an industrial station are used. Various learning methods and varied numbers of hidden layer processing units of the neural network model are tested. Results obtained from the time-series and neural network models are discussed and compared on the basis of their performance for 1-step-ahead and 24-step-ahead forecasts. Although both models perform well for 1-step-ahead prediction, some neural network results reveal a slightly better forecast without manually adjusting model parameters, according to the results. For a 24-step-ahead forecast, most neural network results are as good as or superior to those of the time-series model. With the advantages of self-learning, self-adaptation, and parallel processing, the neural network approach is a promising technique for developing an automated short-term ambient air quality forecast system.

Antiarrhythmic effect of magnolol and honokiol during acute phase of coronary occlusion in anesthetized rats: influence of L-NAME and aspirin

This study was designed to evaluate the in vivo effect of magnolol and honokiol on the acute phase of coronary ligation in the presence of nitric oxide inhibitor (L-NAME) or cyclooxygenase inhibitor (aspirin). After Sprague-Dawley rats were anesthetized with urethane, the changes of ventricular arrhythmia induced by coronary ligation for 30 min were determined with or without pretreatment with study medications. The incidence and duration of ventricular arrhythmia were significantly reduced after intravenous pretreatment (15 min before coronary ligation) with 10(-7) g/kg magnolol or 10(-7) g/kg honokiol. However, the antiarrhythmic effect of magnolol or honokiol could be abolished with the pretreatment of 1 mg/kg L-NAME, but not with pretreatment of 100 mg/kg aspirin. The abolishment of the myocardial beneficial effect of magnolol and honokiol by L-NAME, instead of aspirin, suggests an involvement of an increased nitric oxide synthesis in the protection offered by magnolol and honokiol against arrhythmia during myocardial ischemia.

An active site of transforming growth factor-beta(1) for growth inhibition and stimulation

Transforming growth factor-beta (TGF-beta) is a bifunctional growth regulator. It inhibits growth of many cell types, including epithelial cells, but stimulates growth of others (e.g. fibroblasts). The active site on the TGF-beta molecule, which mediates its growth regulatory activity, has not been defined. Here, we show that antibody to a TGF-beta(1) peptide containing the motif WSLD (52nd to 55th amino acid residues) completely blocked both (125)I-TGF-beta(1) binding to TGF-beta receptors and TGF-beta(1)-induced growth inhibition in mink lung epithelial cells. Site-directed mutagenesis analysis revealed that the replacement of Trp(52) and Asp(55) by alanine residues diminished the growth inhibitory activity of TGF-beta(1) by approximately 90%. Finally, while wild-type TGF-beta(1) was able to stimulate growth of transfected NIH 3T3 cells, the double mutant TGF-beta(1) W52A/D55A was much less active. These results support the hypothesis that the WSLD motif is an active site of TGF-beta(1), which is important for growth inhibition of epithelial cells and growth stimulation of fibroblasts.

The mannose 6-phosphate/insulin-like growth factor-II receptor is a substrate of type V transforming growth factor-beta receptor

The type V transforming growth factor beta (TGF-beta) receptor (TbetaR-V) is a ligand-stimulated acidotropic Ser-specific protein kinase that recognizes a motif of SXE/S(P)/D. This motif is present in the cytoplasmic domain of the mannose 6-phosphate/insulin-like growth factor-II (Man-6-P/IGF-II) receptor. We have explored the possibility that the Man-6-P/IGF-II receptor is a substrate of TbetaR-V. Purified bovine Man-6-P/IGF-II receptor was phosphorylated by purified bovine TbetaR-V in the presence of [gamma-32P]ATP and MnCl2 with an apparent Km of 130 nM. TGF-beta stimulated the phosphorylation of the Man-6-P/IGF-II receptor at 0 degrees C in mouse L cells overexpressing the Man-6-P/IGF-II receptor and in wild-type mink lung epithelial (Mv1Lu cells) metabolically labeled with [32P]orthophosphate. The in vitro and in vivo phosphorylation of the Man-6-P/IGF-II receptor occurred at the putative phosphorylation sites as revealed by phosphopeptide mapping and amino acid sequence analysis. TGF-beta stimulated Man-6-P/IGF-II receptor-mediated uptake (approximately 2-fold after 12 h treatment) of exogenous beta-glucuronidase in Mv1Lu cells and type II TGF-beta receptor (TbetaR-II)-defective mutant cells (DR26 cells) but not in type I TGF-beta receptor (TbetaR-I)-defective mutant cells (R-1B cells) and human colorectal carcinoma cells (RII-37 cells) expressing TbetaR-I and TbetaR-II but lacking TbetaR-V. These results suggest the Man-6-P/IGF-II receptor serves as an in vitro and in vivo substrate of TbetaR-V and that both TbetaR-V and TbetaR-I may play a role in mediating the TGF-beta-stimulated uptake of exogenous beta-glucuronidase.

Cell surface retention sequence binding protein-1 interacts with the v-sis gene product and platelet-derived growth factor beta-type receptor in simian sarcoma virus-transformed cells

The cell surface retention sequence (CRS) binding protein-1 (CRSBP-1) is a newly identified membrane glycoprotein which is hypothesized to be responsible for cell surface retention of the oncogene v-sis and c-sis gene products and other secretory proteins containing CRSs. In simian sarcoma virus-transformed NIH 3T3 cells (SSV-NIH 3T3 cells), a fraction of CRSBP-1 was demonstrated at the cell surface and underwent internalization/recycling as revealed by cell surface 125I labeling and its resistance/sensitivity to trypsin digestion. However, the majority of CRSBP-1 was localized in intracellular compartments as evidenced by the resistance of most of the 35S-metabolically labeled CRSBP-1 to trypsin digestion, and by indirect immunofluorescent staining. CRSBP-1 appeared to form complexes with proteolytically processed forms (generated at and/or after the trans-Golgi network) of the v-sis gene product and with a approximately 140-kDa proteolytically cleaved form of the platelet-derived growth factor (PDGF) beta-type receptor, as demonstrated by metabolic labeling and co-immunoprecipitation. CRSBP-1, like the v-sis gene product and PDGF beta-type receptor, underwent rapid turnover which was blocked in the presence of 100 microM suramin. In normal and other transformed NIH 3T3 cells, CRSBP-1 was relatively stable and did not undergo rapid turnover and internalization/recycling at the cell surface. These results suggest that in SSV-NIH 3T3 cells, CRSBP-1 interacts with and forms ternary and binary complexes with the newly synthesized v-sis gene product and PDGF beta-type receptor at the trans-Golgi network and that the stable binary (CRSBP-1.v-sis gene product) complex is transported to the cell surface where it presents the v-sis gene product to unoccupied PDGF beta-type receptors during internalization/recycling.

Interactions of high affinity insulin-like growth factor-binding proteins with the type V transforming growth factor-beta receptor in mink lung epithelial cells

High affinity insulin-like growth factor-binding proteins (IGFBP-1 to -6) are a family of structurally homologous proteins that induce cellular responses by insulin-like growth factor (IGF)-dependent and -independent mechanisms. The IGFBP-3 receptor, which mediates the IGF-independent growth inhibitory response, has recently been identified as the type V transforming growth factor-beta receptor (TbetaR-V) (Leal, S. M., Liu, Q. L., Huang, S. S., and Huang, J. S. (1997) J. Biol. Chem. 272, 20572-20576). To characterize the interactions of high affinity IGFBPs with TbetaR-V, mink lung epithelial cells (Mv1Lu cells) were incubated with 125I-labeled recombinant human IGFBPs (125I-IGFBP-1 to -6) in the presence of the cross-linking agent disuccinimidyl suberate and analyzed by 5% SDS-polyacrylamide gel electrophoresis and autoradiography. 125I-IGFBP-3, -4, and -5 but not 125I-IGFBP-1, -2, and -6 bound to TbetaR-V as demonstrated by the detection of the approximately 400-kDa 125I-IGFBP.TbetaR-V cross-linked complex in the cell lysates and immunoprecipitates. The analyses of 125I-labeled ligand binding competition and DNA synthesis inhibition revealed that IGFBP-3 was a more potent ligand for TbetaR-V than IGFBP-4 or -5. Most of the high affinity 125I-IGFBPs formed dimers at the cell surface. The cell-surface dimer of 125I-IGFBP-3 preferentially bound to and was cross-linked to TbetaR-V in the presence of disuccinimidyl suberate. IGFBP-3 did not stimulate the cellular phosphorylation of Smad2 and Smad3, key transducers of the transforming growth factor-beta type I/type II receptor (TbetaR-I.TbetaR-II) heterocomplex-mediated signaling. These results suggest that IGFBP-3, -4, and -5 are specific ligands for TbetaR-V, which mediates the growth inhibitory response through a signaling pathway(s) distinct from that mediated by the TbetaR-I and TbetaR-II heterocomplex.

Effects of l-amphetamine on the central neurons of the snail

The effects of l-amphetamine on the spontaneous firing of central neurons of African snails (Achatina fulica Ferussac) were studied electrophysiologically. The effects of dopamine, noradrenaline, d-amphetamine, and methamphetamine on the central neurons also were tested. The l- and d-amphetamines (0.3 mM) elicited bursting firing of action potentials in the RP4 neuron of the snail, whereas dopamine (0.3 mM), noradrenaline (NE, 0.3 mM), and methamphetamine (2 mM) did not. The bursting firing of action potentials elicited by l-amphetamine was decreased if potassium-free solution, sodium-free solution, or solution containing oubain (0.1 mM), a sodium pump inhibitor, was perfused. The results suggested that l-amphetamine did, and methamphetamine did not, elicit a sodium-dependent bursting firing of action potentials of the neuron.

[Effects of endogenous nitric oxide on pulmonary artery hypertension and lung injury induced by endotoxin]

Changes in mean artery pressure (MAP), pulmonary artery pressure (PAP) and nitric oxide (NO) contents in inflow and outflow pulmonary blood(IPB,OPB) were observed after endotoxin lipopolysacchride (LPS) was injected i.v. in rabbits. Changes of PAP and lung injury were also observed after inhibitor of NO synthesis L-NNA or inhibitor of inducible NO synthesis AG was pre-injected by vein. The results showed that MAP decreased significantly after LPS administration, and 0.5-2h later PAP showed some increase (P<0.05) being maximum at PAP (1h) during which the content of NO in IPB was detectably decreased but NO in OPB did not. NO contents in OPB at 3h and in IPB and OPB at 5h increased significantly following LPS administration as compared with control.PAP correlated negatively with NO in IPB at the time before and 1h after LPS injection, which did not exist at 3 and 5h after LPS injection. After L-NNA pretreatment, when PAP elevated significantly, the MDA content in IPB and OPB also showed significant increase, while animal survival rate fell significantly. Light microscopic examination showed severe alveolar atelectasis, significant congestion and sequestration of leukocytes in lung tissue. When pretreated with AG, MAP elevated significantly in 3-5h, PAP remained unchanged. The MDA content in blood was lower at 5h in the LPS injected group with less pathological changes in lung tissue at 5h compared with the LPS group. The above results suggested that there was pulmonary hypertension in the early stage after endotoxin administration. The decrease of NO content in IPB may be one of the mechanisms underlying pulmonary artery hypertension(PAH).NO seemed to alleviate PAH and lung injury at the early stage after endotoxin administration. When iNOS was induced at the later stage, NO contributed to lung injury caused by endotoxin.

Amyloid beta-peptide possesses a transforming growth factor-beta activity

Amyloid beta-peptide (Abeta) of 39-42 amino acid residues is a major constituent of Alzheimer's disease neurite plaques. Abeta aggregates (fibrils) are believed to be responsible for neuronal damage and dysfunction, as well as microglia and astrocyte activation in disease lesions by multiple mechanisms. Since Abeta aggregates possess the multiple valencies of an FAED motif (20th to 23rd amino acid residues), which resembles the putative transforming growth factor-beta (TGF-beta) active site motif, we hypothesize that Abeta monomers and Abeta aggregates may function as TGF-beta antagonists and partial agonists, analogous to previously described monovalent and multivalent TGF-beta peptide antagonists and agonists (Huang, S. S., Liu, Q., Johnson, F. E., Konish, Y., and Huang, J. S. (1997) J. Biol. Chem. 272, 27155-27159). Here, we report that the Abeta monomer, Abeta-(1-40) and its fragment, containing the motif inhibit radiolabeled TGF-beta binding to cell-surface TGF-beta receptors in mink lung epithelial cells (Mv1Lu cells). Abeta-(1-40)-bovine serum albumin conjugate (Abeta-(1-40)-BSA), a multivalent synthetic analogue of Abeta aggregates, exhibited cytotoxicity toward bovine cerebral endothelial cells and rat post-mitotic differentiated hippocampal neuronal cells (H19-7 cells) and inhibitory activities of radiolabeled TGF-beta binding to TGF-beta receptors and TGF-beta-induced plasminogen activator inhibitor-1 expression, that were approximately 100-670 times more potent than those of Abeta-(1-40) monomers. At less than micromolar concentrations, Abeta-(1-40)-BSA but not Abeta-(1-40) monomers inhibited proliferation of Mv1Lu cells. Since TGF-beta is an organizer of responses to neurodegeneration and is also found in neurite plaques, the TGF-beta antagonist and partial agonist activities of Abeta monomers and aggregates may play an important role in the pathogenesis of the disease.

Activated thyroglobulin possesses a transforming growth factor-beta activity

Thyroglobulin (Tg), the thyroid hormone precursor, is a major protein component in the thyroid gland and may have other important functions. Here, we show that bovine Tg inhibited 125I-labeled transforming growth factor-beta1 (125I-TGF-beta1) binding to cell-surface TGF-beta receptors in mink lung epithelial cells with an IC50 of approximately 300 nM. After disuccinimidyl suberate (DSS) modification, reduction/alkylation, treatment with 8 M urea, 0. 1% SDS, or acidic pH (pH 4-5), Tg exhibited a approximately 5-10-fold increase of 125I-TGF-beta1 binding inhibitory activity with IC50 of approximately 30-60 nM. This inhibitory activity was an intrinsic property of the Tg and could not be segregated from Tg protein by 5% SDS-polyacrylamide gel electrophoresis or by immunoprecipitation using antiserum to Tg. Untreated Tg did not affect DNA synthesis but blocked the TGF-beta-induced inhibition of DNA synthesis in mink lung epithelial cells. After DSS activation, Tg possessed TGF-beta agonist activity and inhibited DNA synthesis of mink lung epithelial cells and rat thyroid cells. The activated Tg also exerted a small but significant TGF-beta agonist activity in transcriptional activation of plasminogen activator inhibitor-1. These results suggest that Tg possesses an authentic TGF-beta activity which can be induced by chemical modifications and treatments with denaturing agents and acidic pH.

Glucocorticoids modulate the biosynthesis and processing of prothyrotropin releasing-hormone (proTRH)

The thyrotropin- (TRH) releasing hormone precursor (26 kDa) undergoes proteolytic cleavage at either of two sites, generating N-terminal 15 kDa/9.5 kDa or C-terminal 16.5/10 kDa intermediate forms that are processed further to yield five copies of TRH-Gly and seven non-TRH peptides. Glucocorticoids (Gcc) have been shown to enhance TRH gene expression in three different cell systems in vitro, an effect that occurs, at least in part, through transcriptional activation. Although this implies that an increase of TRH prohormone biosynthesis would take place, this had not been demonstrated as yet. We report here that the synthetic glucocorticoid dexamethasone (Dex) substantially elevated the de novo biosynthesis of the intact 26-kDa TRH prohormone and its intermediate products of processing in cultured anterior pituitary cells, an observation that is consistent with an overall upregulation of both the biosynthesis and degradation of the TRH precursor. We reasoned that Gcc may act not only at the transcriptional, but also at the translational/posttranslational level. To address this question we chose a different cell system, AtT20 cells transfected with a cDNA encoding preproTRH. Since TRH gene expression in these cells is driven by the CMV-IE promoter and not by an endogenous "physiological" promoter, these cells provide an ideal model to study selectively the effects of Gcc on the translation and posttranslational processing of proTRH without interference from a direct transcriptional activation of the TRH gene. Dex caused a significant 75.7% increase in newly synthesized 26-kDa TRH prohormone, suggesting that the glucocorticoid raised the translation rate. We then demonstrated that Dex treatment accelerated TRH precursor processing. Of interest, processing of the N- vs the C-terminal intermediate was influenced differentially by the glucocorticoid. Although the N-terminal intermediate product of processing accumulated, the C-terminal intermediate was degraded more rapidly. Consistent with these observations was the finding that the intracellular accumulation of the N-terminally derived peptide preproTRH 25-50 was enhanced, but levels of the C-terminally derived peptide preproTRH208-255 were reduced. Accumulation of TRH itself, whose five copies are N- and C-terminally derived, was also enhanced. We conclude that Gcc induce changes in the biosynthesis and processing of proTRH by increasing the translation rate and by differentially influencing the processing of N- vs C-terminal intermediates of the precursor molecule. These effects of Gcc at the translational and posttranslational levels result in an increase in TRH production accompanied by differential effects on the accumulation of N- and C-terminal non-TRH peptides.

Survival prolongation in HIV-associated progressive multifocal leukoencephalopathy treated with alpha-interferon: an observational study

A retrospective chart review was conducted to determine the effect of alpha-Interferon (alpha-IFN) on disease progression, symptom palliation, and survival in HIV-associated Progressive Multifocal Leukoencephalopathy (PML).

METHODS

Subjects were HIV seropositive patients diagnosed with PML at the Johns Hopkins Hospital between 1985 and July of 1986. Diagnostic criteria for PML included both clinical symptomatology and histologic or radiographic confirmation. All patients with concomitant CNS infections were excluded. Patients receiving a minimum treatment of 3 weeks of 3 million units of alpha-IFN daily were compared to untreated historical controls. From 104 PML cases reviewed, 77 met the defined criteria for PML. Twenty-one patients had received open-label alpha-IFN treatment in a non-randomized manner for at least 3 weeks, and 32 met criteria for inclusion in the untreated group as historical controls. Deceased treated patients were comparable to deceased untreated patients with respect to age, gender, race, HIV risk factors, AIDS-defining illnesses, and CD4+ counts. CD4+ counts and use of anti-retroviral medications within 6 months of PML onset were higher among those who were living at the time of the study.

RESULTS

Among deceased patients, median survival of treated patients was 127.5 days longer than that of untreated patients (Chi-square=4.21, P=0.04). When living and deceased treated patients were combined, the median survival was 325 days (range 35 - 1634) versus 121 days (range 46 - 176) in untreated patients (Chi-square=13.47, P < 0.001). When survival times in untreated patients were left-censored to account for possible survivorship bias in treated patients, survival in treated patients remained significantly prolonged (325 days versus 175.5 days, Chi-square=4.65, P=0.03). In addition, use of alpha-IFN was associated with a significant delay in the onset of memory loss (Chi-square=8.59, P < 0.01). Seven alpha-IFN treated patients showed sustained remissions of several months to over a year, with documented improvements in mental status, aphasia, dysarthria, dysphagia, paresis, and dyscoordination. Moreover, four IFN-treated patients had evidence of MRI lesion regression, although this was not always correlated with clinical remission. Four of 32 untreated patients also reported transient symptomatic improvements.

CONCLUSION

This open-label study suggests that alpha-IFN may delay progression, palliate symptoms, and significantly prolong survival in HIV-associated PML, and we therefore suggest that a controlled clinical trial is warranted.

Effects of d-amphetamine on the frequency of the spontaneous contraction of the portal vein in rat

1. Effects of d-amphetamine on the frequency of spontaneous contraction of the longitudinal muscle of the portal vein were studied in Wistar rats. Its effects on the circular muscles of the pulmonary artery and stomach also were tested. 2. d-Amphetamine increased the frequency of the spontaneous contraction of the portal vein. The ratio of the frequency of the spontaneous contraction of the portal vein before and after d-amphetamine treatment also was increased. The effect was not affected in the presence of prazocin, (+)-lysergic acid diethylamide, atropine and haloperidol. These results that the d-amphetamine-elicited response was not due mainly to the activation of adrenergic, serotoninergic (5-HT), cholinergic or dopaminergic receptors. 3. Increasing extracellular calcium or sodium ion concentrations decreased the frequency of the spontaneous contraction of the portal vein. However, the ratios of the frequency of the spontaneous contraction of the rat portal vein before and after d-amphetamine treatment in media containing different extracellular calcium or sodium concentrations were not significantly altered. Tetrodotoxin did not alter the effect of d-amphetamine on the frequency of spontaneous contractions. It appeared that calcium and sodium ions may not take part in the effects of d-amphetamine on the frequency of the portal vein. 4. An increase in extracellular potassium ion concentrations increased the frequency of the spontaneous contractions of the portal vein. In addition, the ratios of the frequency of the spontaneous contractions of the rat portal vein before and after d-amphetamine treatment in media containing different extracellular potassium ion concentrations were significantly altered. Tetraethylammonium chloride (TEA) and 4-aminopyridine (4-AP) increased the spontaneous contractions of the portal vein. However, TEA and 4-AP did not increase the d-amphetamine-elicited increasing effect on the frequency of spontaneous muscle contractions. 5. Levochromakalim, a potassium channel opener, decreased the frequency of the spontaneous contractions of the portal vein. Levochromakalim also decreased the effect of d-amphetamine on the frequency of spontaneous contractions of the muscle. It appeared that potassium ion may be associated with the effects of d-amphetamine on the activity of the portal vein. 6. d-Amphetamine potentiated, whereas prazosin decreased, the noradrenaline-elicited contracture of the rat pulmonary artery in a dose-dependent manner. 7. d-Amphetamine elicited contracture of the circular muscle of rat stomach, whereas it did not alter the frequency of the spontaneous contraction of the muscle. 8. Both 5-HT and d-amphetamine elicited the contracture of the circular muscle of rat stomach. Ketanserin decreased the 5-HT-elicited response, whereas it did not alter the d-amphetamine-elicited response in the muscle. d-Amphetamine did not alter the frequency of the spontaneous contraction of the stomach. 9. It is concluded that d-amphetamine has different effects on the frequency of spontaneous smooth muscle contractions. It increased the frequency in the portal vein, but it did not alter the frequency in stomach circular muscle.

A pentacosapeptide (CKS-25) homologous to retroviral envelope proteins possesses a transforming growth factor-beta activity

CKS-17, a synthetic heptadecapeptide homologous to a conserved domain in retroviral envelope protein p15E, mimics the immunosuppressive properties of p15E in vitro and in vivo, but the mechanisms are not understood. Here we report that a synthetic pentacosapeptide designated CKS-25, a longer version of CKS-17 that contains a functional transforming growth factor-beta3 (TGF-beta3) active-site motif (RXXD), inhibits 125I-labeled TGF-beta1 (125I-TGF-beta1) binding to cell-surface TGF-beta receptors in cultured epithelial cells. Multiple conjugation of CKS-25 to bovine serum albumin and carbonic anhydrase enhances the 125I-TGF-beta1 binding inhibitory activity and confers a partial TGF-beta agonist activity (growth inhibition but not transcriptional activation). Since TGF-beta is a potent immunosuppressive factor, these results suggest that the immunosuppressive properties of CKS-17-bovine serum albumin conjugate and p15E are mediated at least in part by their TGF-beta agonist activities.

Trilinolein inhibits the adhesion of neutrophils to endothelial cells

1. Trilinolein is a triacylglycerol with linoleic acid as the only type of fatty acid in all three esterified positions of glycerol. It was recently reported to have a myocardial protective effect in coronary ligated rats. We now study its effect on the adhesion of human neutrophils to cultured bovine endothelial cells. 2. Pretreatment of an endothelial monolayer with trilinolein at concentrations ranging from 10(-10) to 10(-6) mol/L significantly inhibited neutrophil adhesion to endothelial cells. Trilinolein was less potent than sodium nitroprusside in inhibiting neutrophil adhesion. 3. The inhibitory effect of trilinolein was antagonized by methylene blue and N(G)-nitro-L-arginine methyl ester. The inhibitory effect of trilinolein was not mediated through linoleic acid because linoleic acid did not inhibit neutrophil adhesion. 4. Pretreatment of neutrophils with trilinolein did not reduce neutrophil adhesion. However, in neutrophils activated with N-formyl-methionyl-leucyl-phenylalanine, trilinolein inhibited the neutrophil adhesion to endothelial cells. 5. We conclude that trilinolein inhibits neutrophil adhesion to the endothelial monolayer by stimulating the nitric oxide and cyclic GMP pathways in endothelial cells. It may also inhibit neutrophil adhesion by scavenging free radicals. The inhibitory effect of trilinolein on neutrophil adhesion may play a role in its myocardial protective activity.

The accuracy of medical records and police reports in determining motor vehicle crash characteristics

OBJECTIVE

To determine the accuracy of police, emergency department, and ambulance records in describing motor vehicle crash (MVC) characteristics when compared with a crash investigation report (CIR).

METHODS

This study was a retrospective record review. Sixty-three motor vehicle crash (MVC) patients transported to a university hospital emergency department via ambulance and also reported in a crash investigation record (CIR) during the period January 1993 to December 1995 comprised the study population. The crash characteristics analyzed were occupant position (OP), restraint use (RU), air bag deployment (AD), type of impact (TI), ejection (EJ), and external cause-of-injury code (EC). The accuracies of the police report (PR), the emergency department record (EDR), and the ambulance report (AR) for each patient were compared with the CIR by computing percent agreement, with 95% confidence intervals (95% CIs) for each variable and for each data source.

RESULTS

Overall average agreement was 92.9% for PR, 89.7% for EDR, and 80.7% for AR. The overall average agreement for each variable was 98.9% for EJ, 92.1% for AD, 91.5% for OP, 90.5% for EC, 77.2% for RU, and 76.2% for TI. For all but one variable (RU), 95% CIs overlapped between data sources.

CONCLUSIONS

The accuracy of data sources used to determine crash characteristics varies. Using a CIR as the standard, the PR was the most accurate. Inaccuracies occurred most frequently for RU and TI. Researchers and clinicians need to be aware of these inaccuracies.

Laryngeal candidiasis in children

Candidiasis of the larynx is rare and often related to immunocompromised hosts. We here report a case of laryngeal candidiasis in an immunocompetent infant. The diagnosis was obtained by direct fibre-optic laryngoscopy with specimens submitted for culture. He received anti-fungal medication and was quite well at 1-year follow up. The pertinent literature is also reviewed.

Suramin enters and accumulates in low pH intracellular compartments of v-sis-transformed NIH 3T3 cells

Using acridine orange as a reporter compound, we demonstrate that suramin enters and accumulates in low pH intracellular compartments (endosomes, lysosomes, and trans-Golgi complex) of normal and v-sis-transformed NIH 3T3 cells. The concentration of suramin in these acidic compartments is estimated to be > 150 microM, higher than the concentration known to completely inhibit interaction of the platelet-derived growth factor (PDGF) receptor and v-sis gene product. These results support the hypothesis that suramin reverses the transformed phenotype of v-sis-transformed cells by entering the cell via endocytosis and blocking interaction of the v-sis gene product and PDGF receptor in intracellular organelles.

Transforming growth factor beta peptide antagonists and their conversion to partial agonists

Transforming growth factor beta (TGF-beta) has been implicated in the pathogenesis of various human diseases. Synthetic TGF-beta antagonists therefore could have therapeutic utility. Here we show the development of such compounds. Three synthetic pentacosapeptides designated beta125-(41-65), beta225-(41-65), and beta325-(41-65), whose amino acid sequences correspond to the 41st to 65th amino acid residues of TGF-beta1, TGF-beta2, and TGF-beta3, respectively, inhibit the binding of 125I-labeled TGF-beta isoforms to TGF-beta receptors in mink lung epithelial cells with IC50 of approximately 0.06-2 microM. beta125-(41-65) blocks TGF-beta1-induced growth inhibition and TGF-beta1-induced plasminogen activator inhibitor-1 expression in these cells. The variants designated beta125-(41-65)W52A/D55A and beta325-(41-65)R52A/D55A, in which both Trp52/Arg52 and Asp55 are replaced by alanine residues, do not have TGF-beta antagonist activity. Multiple conjugation of beta125-(41-65) to carrier proteins enhances its antagonist activity but also confers partial agonist activity as measured by DNA synthesis inhibition. These results suggest that the (W/R)XXD motif is important for the activities of these TGF-beta peptide antagonists and that this motif may be the active site sequence of TGF-beta.

Effects of 3,3-dipyridylmethyl-1-phenyl-2-indolinone on gamma-aminobutyric acid elicited chloride current of snail central neuron

The effects of (1) gamma-aminobutyric acid (GABA) on the excitable membrane and (2) DPMPI (3,3-dipyridylmethyl-1-phenyl-2-indolinone) on the microperfused GABA elicited currents were investigated on central LP5 neuron of giant African snail, Achatina fulica Ferussac, with conventional voltage-clamp technique. GABA elicited an inward current of LP5 neuron by a concentration and voltage dependent manner. Muscimol, GABAA receptor agonist, did, while baclofen, GABAB receptor agonist, did not, elicit the membrane current on the neuron. The GABA elicited currents in LP5 neuron were blocked by picrotoxin, a GABAA receptor ion channel complex antagonist while the currents were not blocked by phaclofen, a GABAB receptor antagonist. The results suggested that the GABA elicited current in LP5 neuron was mainly due to activation of GABAA receptor. DPMPI increased the frequency of the spontaneously generated action potential of the neuron. In the voltage clamped neuron, DPMPI decreased the GABA elicited responses by a concentration dependent manner. DPMPI altered neither the reversal potential of GABA elicited current, nor the membrane resistance of the excitable membrane of central LP5 neuron. The results concluded that DPMPI altered the GABAA activated receptor ionic channel complex of the LP5 neuron.

The type V transforming growth factor beta receptor is the putative insulin-like growth factor-binding protein 3 receptor

Insulin-like growth factor-binding protein 3 (IGFBP-3) has been shown to inhibit cell growth by IGF-dependent and -independent mechanisms. The putative cell-surface IGFBP-3 receptor that mediates the IGF-independent growth inhibition has not been identified. Here we show that recombinant human IGFBP-3 inhibits 125I-transforming growth factor (TGF)-beta1 binding to the type V TGF-beta receptor (Mr 400,000) in mink lung epithelial cells. We also demonstrate that the approximately 400-kDa 125I-IGFBP-3 affinity-labeled putative IGFBP-3 receptor is immunoprecipitated by specific antiserum to the type V TGF-beta receptor. The 125I-IGFBP-3 affinity labeling of the putative receptor and IGFBP-3-induced growth inhibition as measured by DNA synthesis in these cells is blocked by a TGF-beta1 peptide antagonist. The 125I-IGFBP-3 affinity-labeled putative receptor can only be detected in cells expressing the type V TGF-beta receptor, but not in cells lacking the type V TGF-beta receptor. These results indicate that the type V TGF-beta receptor is the putative IGFBP-3 receptor and that IGFBP-3 is a functional ligand for the type V TGF-beta receptor.