Regulatory proteins of R-Ras, TC21/R-Ras2, and M-Ras/R-Ras3

We studied the regulation of three closely related members of Ras family G proteins, R-Ras, TC21 (also known as R-Ras2), and M-Ras (R-Ras3). Guanine nucleotide exchange of R-Ras and TC21 was promoted by RasGRF, C3G, CalDAG-GEFI, CalDAG-GEFII (RasGRP), and CalDAG-GEFIII both in 293T cells and in vitro. By contrast, guanine nucleotide exchange of M-Ras was promoted by the guanine nucleotide exchange factors (GEFs) for the classical Ras (Ha-, K-, and N-), including mSos, RasGRF, CalDAG-GEFII, and CalDAG-GEFIII. GTPase-activating proteins (GAPs) for Ras, Gap1(m), p120 GAP, and NF-1 stimulated all of the R-Ras, TC21, and M-Ras proteins, whereas R-Ras GAP stimulated R-Ras and TC21 but not M-Ras. We did not find any remarkable difference in the subcellular localization of R-Ras, TC21, or M-Ras when these were expressed with a green fluorescent protein tag in 293T cells and MDCK cells. In conclusion, TC21 and R-Ras were regulated by the same GEFs and GAPs, whereas M-Ras was regulated as the classical Ras.

Role of the von Hippel-Lindau tumor suppressor protein during neuronal differentiation

The von Hippel-Lindau (VHL) tumor suppressor protein down-regulates transcription by transcriptional elongation enhanced by antagonizing elongin B and C. Transcriptional regulation is an important control mechanism for embryogenesis and tumorigenesis. The VHL gene and protein are expressed in neuronal cells of the fetal and adult brain. However, the role of the VHL gene in the central nervous system (CNS) has not been elucidated. The VHL gene might modify the expression of various genes during embryogenesis and tumorigenesis in CNS. We investigated the role of the VHL gene in CNS development using rodent CNS progenitor cells. Here we show that expression of the VHL protein is correlated with neuronal differentiation but not with glial differentiation in CNS progenitor cells, and we also show that VHL gene transduction induces neuronal differentiation. In addition, a VHL mRNA antisense oligonucleotide inhibits differentiation of CNS progenitor cells and up-regulates their cell cycle. In conclusion, the VHL gene plays an essential role in neuronal differentiation as well as transcription.

Effect of ephedrine on auditory-evoked potentials during light general anaesthesia

Ephedrine, a sympathomimetic drug, may stimulate the central nervous system via its amphetamine-like effect under light general anaesthesia. We compared the effect of ephedrine on auditory-evoked potentials with that of etilefrine, a sympathomimetic drug that lacks an amphetamine-like effect, in patients undergoing abdominal surgery under general anaesthesia with 67% nitrous oxide in oxygen and epidural blockade. Ephedrine (0.08 mg x kg-1 intravenously) significantly decreased the latencies of Nb and P1 from 49.5 (4.2) [mean (SD)] and 63.9 (9.1) ms to 45.9 (4.2) and 59.0 (9.9) ms, respectively; whereas etilefrine (0.02 mg x kg-1 intravenously) caused no significant changes in these potentials. In addition, the latencies of Nb and P1 before drug administration were positively correlated with patient age. These findings suggest that ephedrine can cause excitation of the central nervous system during light general anaesthesia, and that auditory-evoked potentials may be a sensitive indicator of the depth of anaesthesia.

Isolation and characterization of pepsinogen from Trimeresurus flavoviridis (Habu snake)

Pepsinogen was isolated from the gastric mucosa of Trimeresurus flavoviridis (Habu snake) by DEAE-cellulose and DEAE-Sepharose ion-exchange chromatographies, and Sephacryl S-200 gel-chromatography. The yield calculated from the crude extract was 29% with 6.2-fold purification. The purified pepsinogen gave a single band on both native- and SDS-PAGE. As no other active enzyme was detected on the chromatographies, it was concluded that the Habu snake has one major pepsinogen. The molecular mass of the pepsinogen was estimated to be 38 kDa by SDS-PAGE. The sequence of the N-terminal 26 amino acid residues was determined and compared with those of other pepsinogens. The N-terminal structure of Habu snake pepsinogen was more homologous with those of mammalian pepsinogens C than those of mammalian pepsinogens A. The pepsinogen was rapidly converted to pepsin by way of an intermediate form induced by acidification. The optimum pH of Habu snake pepsin for bovine hemoglobin was 1.5-2.0, and it retained full activity at pH 6.2 and 30 degrees C on incubation for 30 min. The optimum temperature for the snake pepsin was 50 degrees C and it was stable at 40 degrees C on incubation for 10 min. The proteolytic activity of the pepsin toward bovine hemoglobin was about two times higher than that of porcine pepsin A, however, the activity toward oxidized bovine insulin B-chain was lower than that of porcine pepsin A, and it did not hydrolyze oligopeptides. The specificity for oxidized bovine insulin B-chain of the pepsin was different from that of porcine pepsin A. Habu snake pepsin was inhibited by pepstatin A but not by serine, cysteine, or metallo protease inhibitors.

Seven-color fluorescence imaging of tissue samples based on Fourier spectroscopy and singular value decomposition

Seven-color analyses of immunofluorescence-stained tissue samples were accomplished using Fourier spectroscopy-based hyperspectral imaging and singular value decomposition. This system consists of a combination of seven fluorescent dyes, three filtersets, an epifluorescence microscope, a spectral imaging system, a computer for data acquisition, and data analysis software. The spectra of all pixels in a multicolor image were taken simultaneously using a Sagnac type interferometer. The spectra were deconvolved to estimate the contribution of each component dye, and individual dye images were constructed based on the intensities of assigned signals. To obtain mixed spectra, three filter sets, i.e., Bl, Gr, and Rd for Alexa488 and Alexa532, for Alexa546, Alexa568, and Alexa594, and for Cy5 and Cy5.5, respectively, were used for simultaneous excitation of two or three dyes. These fluorophores have considerable spectral overlap which precludes their separation by conventional analysis. We resolved their relative contributions to the fluorescent signal by a method involving linear unmixing based on singular value decomposition of the matrices consisting of dye spectra. Analyses of mouse thymic tissues stained with seven different fluorescent dyes provided clear independent images, and any combination of two or three individual dye images could be used for constructing multicolor images.

Therapeutic efficiency of IL-2 gene transduced tumor vaccine for head and neck carcinoma

Transduction of the human interleukin-2 (IL-2) gene into tumor cells was carried out in order to develop a new immunotherapy for advanced head and neck carcinomas with a poor outcome. We transduced the IL-2 gene into KB cells, a head and neck squamous cell carcinoma cell line, using a defective herpes simplex viral (HSV) amplicon vector as a gene transfer vehicle. A high level of IL-2 was secreted by IL-2 gene-transduced KB cells (KB/IL-2). The IL-2 producibility of irradiated KB/IL-2 cells was almost the same as that of non-irradiated cells. In the tumor establishment model in nude mice, IL-2 and interferon-gamma (IFN-gamma) at high concentrations were detected in the sera of mice transplanted with KB/IL-2 cells. The spleen cells of nude mice transplanted with KB/IL-2 cells exhibited high cytotoxic activity compared to those from mice transplanted with KB cells and from untreated mice. Three of five mice transplanted with KB/IL-2 cells rejected tumors. In the treatment of established tumors, therapeutic effects due to irradiated KB/IL-2 were dose-dependent. The suppressive effects on tumor growth were blocked by anti-asialo GM1, anti-human IL-2 and anti-IFN-gamma antibodies. Immunohistochemical observation revealed the presence of asialo GM1(+) cells among the KB/IL-2 cells in tumors transplanted into nude mice.

Regional evolution of venom-gland phospholipase A2 isoenzymes of Trimeresurus flavoviridis snakes in the southwestern islands of Japan

Conventional chromatographic analysis showed that phospholipase A(2) (PLA(2)) isoenzymes of the venom of Trimeresurus flavoviridis (Habu snake) of Okinawa island are profoundly different in composition from those of T. flavoviridis of Amami-Oshima and Tokunoshima islands. The most striking feature was that myotoxic [Lys(49)]PLA(2) isoenzymes, called BPI and BPII, which are expressed abundantly in the venoms of Amami-Oshima and Tokunoshima T. flavoviridis, are missing from the venom of Okinawa T. flavoviridis. Northern blot analysis of Okinawa T. flavoviridis venom-gland mRNA species showed the absence of BPI and BPII mRNA species. Analysis by single-stranded conformational polymorphism-PCR of venom-gland mRNA species of T. flavoviridis from three islands, with reference to five DNA species each encoding different PLA(2) isoenzymes from Tokunoshima T. flavoviridis venom gland, also suggested that BPI and BPII mRNA species are not expressed in Okinawa T. flavoviridis venom gland. In contrast, genomic Southern blot analysis with a variety of probes showed that only the bands corresponding to the upstream and downstream regions of the genes for BPI and/or BPII can be detected in Okinawa T. flavoviridis. These results suggested that the genes for BPI and BPII in Okinawa T. flavoviridis genome had been inactivated to form pseudogenes. Differently from Amami-Oshima and Tokunoshima T. flavovirdis genomic DNAs, PCR amplification of the segments of BPI and BPII genes between the 5' moiety of second exon and the middle portion of second intron failed for Okinawa T. flavoviridis genomic DNAs. In sequence analysis of the two segments involving polymorphism between BPI and BPII genes, which are located in first exon and third exon, respectively, only one base was detected at the polymorphic positions for pseudogene in Okinawa T. flavoviridis genome. Based on these facts, it became evident for pseudogene that the upstream region of BPI gene down to the 5' moiety of second exon and the downstream region of BPII gene starting from the middle portion of second intron are in a linked form with a possible insertion. Such observations suggest that venom-gland genes for PLA(2) isoenzymes in T. flavoviridis snakes isolated for one to two million years have evolved independently. Their evolution is regional and seems, from several lines of consideration and observation, to be adaptive to the environment.

In vivo gene gun-mediated DNA delivery into rodent brain tissue

Various types of gene transfer into live tissues have been tried. However, in vivo gene transfer into brain tissue or neuronal cells without virus vector has required a great effort. Particle-mediated gene transfer into live brain tissue was thought to be impossible because of its fragility and the mechanical problem of a previous type of gene gun. In addition, particle-mediated DNA transfer into monolayer-cultured cells without mechanical damage has been difficult. We successfully transferred DNA into rodent live brain tissue and also into monolayer-cultured cells without mechanical damage by using a new type of gene gun and also confirmed gene expression in the brain. This new method represents another variation of gene transfer into the brain.

High-glucose-induced nuclear factor kappaB activation in vascular smooth muscle cells

OBJECTIVE

Vascular smooth muscle cell (VSMC) dysfunction plays a role in diabetic macrovasculopathy. This dysfunction may be caused or exacerbated by expression of many of genes potently activated by the transcriptional factor nuclear factor kappaB (NF-kappaB). We have examined whether culture of VSMCs under high glucose conditions to stimulate the diabetic state can lead to the activation of NF-kappaB.

METHODS

NF-kappaB activation was assessed in VSMCs stably transfected with a cis-reporter plasmid containing the NF-kappaB binding sites.

RESULTS

Within 3-h incubation, high glucose (27.5 or 55 mmol/l) alone induced an increase in NF-kappaB activity in VSMCs; this increase was mimicked by mannitol given to deliver the same osmolar stress to the cells. High glucose or mannitol also enhanced TNFalpha-stimulated NF-kappaB activity. Incubation with high glucose for 48 h followed by stimulation with TNFalpha led to a marked potentiation of NF-kappaB activation compared with normoglycemic (5.5 mmol/l) VSMCs exposed to TNFalpha, while mannitol attenuated this effect. A 48-h incubation with high glucose substantially reduced glutathione (GSH) levels compared with normoglycemic VSMCs, whereas mannitol significantly increased GSH levels. An antioxidant N-acetyl-L-cysteine and a selective protein kinase C (PKC) inhibitor GF109203X significantly suppressed the TNFalpha-induced NF-kappaB activation, and abrogated potentiation of TNFalpha-induced NF-kappaB activity caused by high glucose (27.5 mmol/l).

CONCLUSION

These results suggest that acutely high glucose causes alterations in osmolarity leading to activation of NF-kappaB, but that exposure to high glucose for more prolonged times causes changes in antioxidant defences and activation of PKC, which potentiates cytokine activation of NF-kappaB. Further definition of these pathways will help to delineate important signals mediating the aberrant behavior of VSMCs under hyperglycemic/diabetic conditions.

Chat, a Cas/HEF1-associated adaptor protein that integrates multiple signaling pathways

Cas (Crk-associated substrate) and HEF1 (human enhancer of filamentation) are related adaptor proteins that function in integrin-mediated cell adhesion and antigen receptor signaling pathways. We report here a molecular cloning of Chat (Cas/HEF1-associated signal transducer) that associates with Cas and HEF1. Chat is a 78-kDa signaling molecule with an N-terminal SH2 domain and is expressed in a wide range of tissues. In hematopoietic cells, a 115-kDa isoform of Chat (Chat-H) was specifically expressed. Chat is associated with Cas in brain, and Chat-H is associated with HEF1 in splenocytes. Deletion analyses revealed that Chat and Cas are associated with each other by their C-terminal domains. Treatment of PC12 cells with epidermal growth factor or nerve growth factor increased the phosphorylation level of Chat. This increase was suppressed by an inhibitor of mitogen-activated protein (MAP) kinase kinase, PD98059, suggesting the phosphorylation of Chat by MAP kinase. In Chat-overexpressed COS7 cells, the activity of c-Jun N-terminal kinase was up-regulated. After the epidermal growth factor stimulation, Chat and Cas were colocalized with actin filaments at ruffling membranes. These findings suggest that Chat transduces signals of tyrosine kinases and MAP kinase to Cas signaling pathway.

Membranoproliferative glomerulonephritis in congenital portosystemic shunt without liver cirrhosis

We report two cases with congenital portosystemic shunt who developed renal lesions without liver cirrhosis. Clinically, both cases showed proteinuria and mild hematuria at 9 and 6 years of age, respectively. In one case, the renal lesion was associated with normal renal function, but nephrotic syndrome followed by chronic renal failure were noted in the other. Renal biopsies showed characteristic histological features of membranoproliferative glomerulonephritis (MPGN) with IgA deposits along the glomerular capillary wall. Our cases strongly suggest the association between congenital portosystemic shunt and renal region. The shunt ratio may be an important predisposing factor for this type of nephropathy since a high shunt ratio (> 90%) was noted in both cases.

[A study on the risk factors for tuberculosis epidemics observed from the results of extraordinary health examinations]

In recent years, tuberculosis (tbc) epidemics have been increasing, and have become a social problem in Japan. This study was carried out to clarify the current risk factors on tbc epidemics. The original reports of a total of 254 tbc patients whose contacts were examined for possible tbc infection (extraordinary health examinations) during 1992-97, were investigated and compared with all new pulmonary tbc cases registered during the same period in Aichi prefecture. In addition, from registration cards in each public health center, the risk factors for 19 cases of both tbc epidemics (infecting more than 20 contacts) and microepidemics infecting 10-19 contacts were further examined. The results obtained were as follows; 1. Extraordinary health examinations were carried out in 3.2% of total pulmonary tbc cases, and were carried out at higher rates among contacts with younger patients and with those having severer tbc by radiographical (p < 0.01) and bacteriological findings (p < 0.01). 2. 11 tbc epidemics (3.4%) and 34 microepidemics (14.3%) were identified among 254 examinations over 6 years. They were frequently observed in groups with abundant bacilli discharge and long lasting cough, and also in young age groups. 3. All of the 19 cases causing epidemics or microepidemics had multiple risk factors; the main factors being late diagnosis, inadequate health managements in schools and offices and poor quality of patients' living environments. Therefore, it is necessary for public health centers to work more closely with schools and industrial circles for the prevention of tbc epidemics.

[Clinical efficacy of cefpirome sulfate against Bacteroides species, Prevotella species and Porphyromonas species. Society of Anaerobic Bacterial Infections in the fields of obstetrics and gynecology in Gifu]

The injectable cephalosporin cefpirome (CPR) was launched in Japan in 1993. It has widely been used in the various infectious diseases. We therefore studied the clinical and bacteriological efficacy of CPR against infections caused by Bacteroides species, Prevotella species and Porphyromonas species frequently isolated from the obstetric and gynecologic infections. Thirteen institutions were involved in this study which ran from March 1994 to January 1999. The administration dosage of CPR was 2 to 4 gram per day administered by drip infusion or intravenous infusion. The duration of treatment was from 3 to 15 days. The evaluations were performed before and after the treatment. CPR was administered to 194 patients with obstetric and gynecologic infections, and 146 of 194 cases were acceptable for the evaluation of drug efficacy. Bacteroides species were identified in 102 patients. Clinical efficacy in 146 cases was excellent in 12 patients, good in 110, fair in 9 and poor in 15 patients. The eradication rate for Bacteroides species could be in 37 cases out of 54 evaluable cases; Prevotella species in 38 out of 49; and Porphyromonas species in 5 out of 5. The overall assessment of bacteriological efficacy was "eradicated" in 91 cases out of 133 (68.4%). Adverse reactions including abnormal findings in laboratory tests were seen in 8 patients (4.76%). Based on these results, CPR promises efficacy and safety in the treatment of obstetric and gynecologic infections due to Bacteroides species.

Successful treatment of Kimura's disease with cyclosporine

We report the case of a 29-year-old Japanese woman presenting with recurring Kimura's disease. We began treatment with cyclosporine within 7 days, the nodular lesion had almost cleared. The cyclosporine dose was then gradually reduced and discontinued after 6 months. The patient was reassessed 18 months after the cessation of treatment and there was no evidence of recurrence of the disease. We speculate that the effects of cyclosporine on T helper-2 cells improves Kimura's disease.

Evidence of HIV type 1 glycoprotein 120 binding to recombinant N-methyl-D-aspartate receptor subunits expressed in a baculovirus system

Activation of the N-methyl-D-aspartate (NMDA) receptor by HIV-1 envelope glycoprotein 120 (gp120) is thought to represent at least one of the pathways causing neuronal damage in AIDS patients. In the present study, recombinant gp120 binding to NMDA receptor subunits expressed in a baculovirus system was examined by immunocytochemistry and a binding assay, using horseradish peroxidase (HRP)-conjugated and 125I-labeled recombinant gp120, respectively. We found that recombinant gp120 binds to Sf21 cells expressing epsilon1/zeta1 or epsilon2/zeta1 combined NMDA receptor subunits, but not to Sf21 cells infected with mock virus or Sf21 cells expressing a single epsilon1, epsilon2, or zeta1 NMDA receptor subunit. The binding was strongly blocked by unlabeled recombinant gp120, monoclonal anti-HIV-1 gp160 antibody, and a mixture of anti-epsilon1/epsilon2 and anti-zeta1 antibodies. The same results were obtained by flow cytometric analysis. These data suggest that HIV-1 gp120 may directly bind to the NMDA receptor. This evidence enhances our understanding of the mechanism of HIV-1-induced neuronal damage in AIDS patients.

Mouse semaphorin H induces PC12 cell neurite outgrowth activating Ras-mitogen-activated protein kinase signaling pathway via Ca(2+) influx

We recently showed that mouse semaphorin H (MSH), a secreted semaphorin molecule, acts as a chemorepulsive factor on sensory neurites. In this study, we found for the first time that MSH induces neurite outgrowth in PC12 cells in a dose-dependent manner. Comparison of Ras-mitogen-activated protein kinase (MAPK) signaling pathways between MSH and nerve growth factor (NGF) revealed that these pathways are crucial for MSH action as well as NGF. K-252a, an inhibitor of tyrosine autophosphorylation of tyrosine kinase receptors (Trks), did not inhibit the action of MSH, suggesting that MSH action occurs via a different receptor than NGF. L- and N-types of voltage-dependent Ca(2+) channel blockers, diltiazem and omega-conotoxin, inhibited MSH-induced neurite outgrowth and MAPK phosphorylation in a Ca(2+)-dependent manner. A transient elevation in intracellular Ca(2+) level was observed upon MSH stimulation. These findings suggest that extracellular Ca(2+) influx, followed by activation of the Ras-MAPK signaling pathway, is required for MSH induced PC12 cell neurite outgrowth.

IgE reactivity to alpha1 and alpha2 chains of bovine type 1 collagen in children with bovine gelatin allergy

BACKGROUND

Anaphylactic reactions to measles, mumps, and rubella vaccines, including gelatin as a stabilizer, have been reported. It had been found that most of these reactions to live vaccines are caused by the bovine gelatin included in these vaccines. Gelatin mainly includes denatured type I collagen, which consists of alpha1 and alpha2 chains.

OBJECTIVE

The current study was designed to investigate the IgE reactivity to alpha1 and alpha2 chains of bovine type I collagen in gelatin-sensitive children.

METHODS

Serum samples were taken from 10 children who had anaphylaxis to the vaccines and high levels of specific IgE to bovine gelatin. Bovine type I collagen was isolated from bovine skin and then separated to alpha1 and alpha2 chains by column chromatography. IgE reactivity to denatured type I collagen and its alpha1 and alpha2 chains was analyzed by immunoblotting, ELISA, and histamine release from the mast cells passive sensitized with IgE antibodies in pooled serum of the children.

RESULTS

All children had specific IgE to bovine type I collagen. Furthermore, IgE antibodies in their sera reacted with the alpha;2 chain but not with the alpha1 chain. Similarly, the mast cells sensitized with pooled sera in the children showed alpha2 chain-specific histamine release but not alpha1 chain-specific histamine release.

CONCLUSION

In gelatin allergy denatured bovine type I collagen is a major allergen and IgE-binding sites exist in the alpha2 chain of type I collagen.

Stretch-activated ion channel blocker gadolinium attenuates ischemic ST-segment elevation in canine myocardium

Regional transmural ischemia causes both ST-segment elevation and systolic elongation (bulging) of the myocardium. Mechanical stretch might alter the transmembrane potential via stretch-activated ion channels (SAC); however, the role of SAC on ischemic ST-segment elevation has not yet fully studied. The present study investigated the role of SAC in the genesis of ischemic ST-segment elevation in the in-vivo canine heart. In 6 anesthetized dogs, an extracorporeal conduit connected to the left anterior descending coronary artery was occluded for 5 min before and after the intracoronary infusion of gadolinium (Gd, 500 micromol/min). To eliminate the effect of ischemic preconditioning, the bypass was occluded for 5 min before the experiment. Percent systolic shortening (%SS) and percent systolic elongation (%bulging) were measured using a pair of ultrasonic dimension crystals. A unipolar epicardial ECG was monitored at the center of the ischemic area for the measurement of the ST-segment level. At the end of coronary occlusion, there was no difference in the reduction of %SS or the increase of %bulging between before and after infusion of Gd. ST-segment elevation, however, was significantly attenuated by the infusion of Gd. These data demonstrated that the activation of SAC is one cause of ischemic ST-segment elevation.

Nonischemic ST-segment elevation induced by negative inotropic agents

The present study investigated whether regional ventricular dyskinesia (ie, systolic bulging) is a direct cause of ST-segment elevation in canine hearts in vivo. Regional ventricular dyskinesia was induced in 33 anesthetized open-chest dogs by injection of negative inotropic agents into the left anterior descending coronary artery (LAD) without disruption of coronary blood flow. Regional myocardial contraction was assessed in terms of the percent systolic shortening (%SS) and percent systolic bulging (%bulging), which were measured using ultrasonic crystals. The ST-segment elevation of the LAD-perfused area was measured with a unipolar electrode. Lidocaine, a sodium channel blocker, nicorandil, a potassium channel opener, propranolol, a beta-adrenergic blocker, or verapamil, a calcium channel blocker, was administered by intracoronary injection during maximal vasodilation induced by adenosine. All drugs induced dose-dependent ST-segment elevation in association with a parallel reduction in %SS and a parallel increase in %bulging. The absence of myocardial ischemia was confirmed by the absence of NADH fluorescence. It was concluded that regional ventricular dyskinesia had an important role in ST-segment elevation not associated with myocardial ischemia.

Screening for aetiology of thrombophilia: a high prevalence of protein S abnormality

We systematically screened for the aetiology of thrombophilia in 115 patients with venous, arterial and small vessel thromboses. Forty-one patients (36% of those we examined) suffering from a variety of thromboses, including deep vein thrombosis, pulmonary embolism, arterial occlusion, cerebral infarction, Moyamoya disease and ulcerative colitis, were characterized either with positive lupus anticoagulants or with decreased activities of protein S, protein C, antithrombin III and/or plasminogen. Eight mutation sites were confirmed in 11 thrombotic patients using gene analysis. Decreased protein S activity was found with a high incidence (23 out of 115) in Japanese patients who suffered from not only venous thrombosis but also arterial and small vessel thrombosis. We emphasize here the important role of protein S in the pathogenesis of thrombosis in the Japanese population.

Interaction of collagen molecules from the aspect of fibril formation: acid-soluble, alkali-treated, and MMP1-digested fragments of type I collagen

Collagen type I extracted with acid or digested with pepsin forms fibrils under physiological conditions, but this ability is lost when the collagen is treated with alkaline solution or digested with matrix metalloproteinase 1 (MMP1). When acid-soluble collagen was incubated with alkali-treated collagen, the fibril formation of acid-soluble collagen was inhibited. At 37 degrees C, at which alkali-treated collagen is denatured, the lag time was prolonged but the growth rate of fibrils was not affected. At 30 degrees C, at which the triple helical conformation of alkali-treated collagen is retained, the lag time was prolonged and the growth rate reduced. Heat-denatured alkali-treated collagen and MMP1-digested fragments have no inhibitory effect on the fibril formation of acid-soluble collagen. This means that the triple helical conformation and the molecular length are important factors in the interaction of collagen molecules and that alkali-treated collagen acts as a competitive inhibitor for fibril formation of collagen. We found that alkali-treated collagen and MMP1-digested fragments form fibrils that lack the D periodic banding pattern and twisted morphology under acidic conditions at the appropriate ionic strength. We also calculated the relative strengths of hydrophobic and electrostatic interactions between collagen molecules. When the hydrophobic interaction between linear collagen molecules was considered, we found a pattern of periodic maximization of the interactive force including the D period. On the other hand, the electrostatic interaction did not show the periodic pattern, but the overall interaction score affected fibril formation.

Futalosine and its derivatives, new nucleoside analogs

Futalosine, a new nucleoside analog, was isolated from a fermentation broth of Streptomyces sp. MK359-NF1. Some chemical derivatives of futalosine were prepared. 6-O-Methylfutalosine methylester inhibited growth of HeLa-S3 cells in vitro (IC50 = 19.5 micrograms/ml) in contrast to the weak activity of futalosine. 6-O-Methylfutalosine methylester at concentrations higher than 10 micrograms/ml inhibited incorporation of 3H-TdR and 3H-UR but not 3H-Leu in the acid-soluble fractions of HeLa-S3 cells.

Comparison of the effects of convulsant and depressant barbiturate stereoisomers on AMPA-type glutamate receptors

BACKGROUND

Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system. Although barbiturates have been shown to suppress the AMPA receptor-mediated responses, it is unclear whether this effect contributes to the anesthetic action of barbiturates. The authors compared the effects of depressant [R(-)] and convulsant [S(+)] stereoisomers of 1-methyl-5-phenyl-5-propyl barbituric acid (MPPB) on the AMPA and gamma-aminobutyric acid type A (GABA(A)) receptor-mediated currents to determine if the inhibitory effects on AMPA receptors correlate to the in vivo effects of the isomers.

METHOD

The authors measured whole-cell currents in the rat cultured cortical neuron at holding potential of -60 mV. Kainate 500 microM was applied as the agonist for AMPA receptors. Thiopental (3-300 microM), R(-)-MPPB or S(+)-MPPB (100-1,000 microM) was coapplied with kainate under the condition in which the GABA(A) receptor-mediated current was blocked. Effects of MPPB isomers on the current elicited by GABA 1 microM were studied in the separate experiments.

RESULTS

Thiopental inhibited the kainate-induced current reversibly and in a dose-dependent manner, with a concentration for 50% inhibition of 49.3 microM. Both R(-)-MPPB and S(+)-MPPB inhibited the kainate-induced current with a little stereoselectivity. R(-)-MPPB was slightly but significantly more potent than S(+)-MPPB. In contrast, R(-)-MPPB enhanced but S(+)-MPPB reduced the GABA-induced current.

CONCLUSIONS

Both convulsant and depressant stereoisomers of the barbiturate inhibited the AMPA receptor-mediated current despite of their opposite effects on the central nervous system in vivo. Although thiopental exhibited a considerable inhibition of AMPA receptors, the results suggest that the inhibition of AMPA receptors contributes little to the hypnotic action of the barbiturates.

The effects of two antiinflammatory pretreatments on bacterial-induced lung injury

BACKGROUND

Two antiinflammatory therapies that have been effective in preventing acid-induced lung injury were evaluated. Specifically, their effects on a subsequent bacterial-airspace challenge were compared. Bacteria were instilled 24 h after acid-induced lung injury. Pseudomonas aeruginosa PAO-1 was used as the bacteria, because its effects in healthy lungs was documented previously.

METHODS

New Zealand white rabbits were anesthetized and three pretreatments were administered: (1) pentoxifylline pretreatment (a 20-mg/kg bolus dose and then 6 mg x kg(-1) x h(-1) given intravenously), (2) 1 ml anti-tumor necrosis factor alpha antiserum given intravenously, or (3) normal saline given intravenously. The pretreatment doses were shown previously to prevent acid-induced lung injury. Then 1.2 ml/kg hydrochloric acid (HCl), pH 1.25, was instilled into the rabbits' right lungs. All the animals underwent mechanical ventilation for 8 h. Twenty-four hours after the acid instillation, the rabbits were anesthetized again and 2 ml/kg (10(9) colony forming units/ml) PAO-1 was instilled into their left lungs. The rabbits' breathing was aided by mechanical ventilation for another 8 h, and then they were killed and exsanguinated.

RESULTS

Both pretreatments attenuated the acid-induced lung injury of the noninstilled left lungs. Arterial oxygen tension and the lung edema of pretreated, acid-exposed animals were significantly and almost equally improved (compared with no pretreatments) by either of the pretreatments. However, when the bacteria were instilled into the left lungs 24 h after the acid injury, the pentoxifylline pretreatment but not the anti-tumor necrosis factor alpha pretreatment prevented much of the bacteria-induced lung injury. Pentoxifylline pretreatment significantly improved the measurements of left lung edema and epithelial and endothelial permeability. There was also a trend for improved oxygenation in the pentoxifylline-pretreated and infected animals. In contrast, the anti-tumor necrosis factor alpha pretreatment did not prevent the bacteria-induced lung injury and increased some of the measurements of lung injury.

CONCLUSIONS

Two antiinflammatory therapies that prevented acid-induced lung injury to the noninstilled left lungs had significantly different effects on a subsequent bacteria-induced lung injury to the left lungs. The therapies differed in their mechanism of tumor necrosis factor alpha blockade, and this may have affected the bacteria-induced injury to the lungs.