Synthesis and biological activity of C-terminally truncated fragments of human alpha-calcitonin gene-related peptide

C-terminally truncated fragments of human alpha-calcitonin gene-related peptide (h-alpha-CGRP) were tested for their ability to stimulate amylase secretion from pancreatic acinar cells and relax precontracted mesenteric arteries. h-alpha-CGRP, h-alpha-CGRP (1-36), h-alpha-CGRP (1-35), and h-alpha-CGRP (1-34) were made by Merrifield's solid-phase peptide synthesis methodology. Peptides were purified by gel filtration, cation-exchange chromatography, and semipreparative reversed-phase high-performance liquid chromatography. The products were characterized by amino acid analysis, mass spectrometry, and tryptic digestion. h-alpha-CGRP stimulated amylase secretion from dispersed guinea pig pancreatic acini in a biphasic concentration-dependent manner. The initial increase in amylase secretion reached 8% of total cellular amylase content with an ED50 value of 7.7 nM, and the second increase reached 11% of total cellular amylase content at a concentration of h-alpha-CGRP of 10(-4)M. h-alpha-CGRP (1-36) caused a small, significant increase in amylase release. C-terminally truncated fragments h-alpha-CGRP (1-35) and h-alpha-CGRP (1-34) did not increase amylase release at concentrations < 10(-5) M. At concentrations > 10(-5) M the fragments h-alpha-CGRP (1-35) and h-alpha-CGRP (1-34) caused a smaller increase in amylase release than that caused by h-alpha-CGRP whereas h-alpha-CGRP (1-36) caused the same increase. h-alpha-CGRP caused a concentration-dependent relaxation of rat mesenteric artery, precontracted with prostaglandin F2 alpha, with an EC50 of 2.9 nM and a maximal relaxation that was 60% of the prostaglandin F2 alpha-induced tone. h-alpha-CGRP (1-35) also relaxed the mesenteric artery in a concentration-dependent manner with a maximum response that was 40% of the prostaglandin F2 alpha-induced tone. The remaining fragments did not relax rat mesenteric arteries. Additionally, h-alpha-CGRP (1-36) and h-alpha-CGRP (1-34) did not block h-alpha-CGRP-induced relaxation of the mesenteric artery. An intact C-terminus is required for h-alpha-CGRP to cause potent biological effects in pancreatic acini and mesenteric artery. The different effects of h-alpha-CGRP (1-35) in mesenteric artery compared with those in pancreatic acini suggest that the CGRP receptors in these two tissues may be different.

[Application of HBV gene subtyping method in study on familial transmission]

A cross-section epidemiological study for hepatitis B was conducted in the population of a village in Hebei Province. The prevalence rate of HBsAg was 3.75% (22/586), and HBV infection rate, 27.65% (162/586), without significant difference between males and females; and increasing with age. This village belongs to a low HBV incidence region in China. This phenomenon might possibly be related to the characteristic of the population (mostly blood donors) and high incidence of HCV (prevalence rate of anti-HCV was 10.31%, 59/572). The anti-HBc and overall HBV infection rate showed family clustering by binomial distribution analysis. The family clustering of HBV infection resulted mainly from the transmission from parents to their children and among the children. The overall positivity rate of HBV DNA was 24.77% (27/109), and the majority of the family members belonged to the same subtypes (72.22%). On the basis of HBV subtyping, familial transmission of HBV was classified into six types, ie. generational, horizontal, recessive, intra- and extra-familial, non-familial and undetermined ones.

Action of histamine on single smooth muscle cells dispersed from the rabbit pulmonary artery

1. The effects of histamine, noradrenaline and caffeine were studied in freshly dispersed smooth muscle cells from the rabbit pulmonary artery using the perforated patch technique. 2. In potassium-containing solutions at a holding potential of -50 mV all three agents evoked net inward and outward currents. At 0 mV only an outward current was observed and this response was not produced in potassium-free conditions. 3. In K(+)-free solutions the reversal potential (Er) of the inward current was dependent upon the transmembrane anion gradient but not on the cation gradient. Thus all three agents produced an increase in potassium and chloride conductance. 4. Bath-applied histamine evoked repetitive potassium and chloride currents in many cells. Bath-applied noradrenaline and caffeine, to a lesser extent, also caused repetitive currents but the brief ionophoretic application of noradrenaline never produced oscillations in membrane current. 5. Histamine reduced or abolished the amplitude of spontaneous transient potassium and chloride currents. 6. Histamine-induced currents were blocked by caffeine (10 mM) but could be recorded in Ca(2+)-free bathing solutions. 7. It is concluded that in the rabbit pulmonary artery histamine evokes single and oscillatory membrane potassium and chloride currents which are mediated by the release of calcium from intracellular caffeine-sensitive stores.

Pulmonary infections of gut origin after major liver resection in rats

OBJECTIVE

To assess the incidence of translocation of enteric bacteria to the lungs in the early postoperative period (1, 2, 4, and 6 hours) after sham operation, 70% hepatectomy, and 90% hepatectomy.

DESIGN

Randomised laboratory experiment.

SETTING

University department.

MATERIAL

96 Adult male Sprague-Dawley rats.

INTERVENTIONS

Sham operation (n = 24), 70% hepatectomy (n = 36), and 90% hepatectomy (n = 36). Injection of 1 ml (1.5 x 10(7) cpm/rat) 125I-labelled heat-killed Escherichia coli 15 minutes before the animals were killed.

MAIN OUTCOME MEASURES

Arterial blood gas analyses, wet: dry weight ratio of lungs, and measurements of pulmonary isotopic flux (amount of 125I radioactivity in the lungs compared with that in the blood) 1, 2, 4, and 6 hours after operation. Quantitative microbiology of lungs.

RESULTS

There was no pulmonary oedema in those rats that underwent sham operation. Pulmonary oedema had developed by 6 hours after 70% hepatectomy and by 2 hours after 90% hepatectomy. The lung:blood ratio of 125I-labelled bacteria increased as the pulmonary oedema developed, but pulmonary oxygen exchange was not influenced during the first 6 hours after hepatectomy. The incidence of bacterial translocation increased with the extent of hepatectomy and with the length of time after operation.

CONCLUSION

Bacterial translocation from the gut could lead to pulmonary infection after major liver resection in rats.

Glu280 is the nucleophile in the active site of Clostridium thermocellum CelC, a family A endo-beta-1,4-glucanase

A new mechanism-based inactivator of beta-1,4-glucanases, 2',4'-dinitrophenyl-2-deoxy-2-fluoro-beta-D-cellobioside, was synthesized and used to trap the intermediate formed during catalysis by endoglucanase C (CelC) from Clostridium thermocellum. Ion spray mass spectrometry confirmed the 1:1 stoichiometry of the incorporation of the inactivator into the enzyme. Inactivation followed the required pseudo first-order kinetic behavior and kinetic parameters for the process were determined. Although the intermediate trapped was relatively stable (t1/2 = 25 h), turnover was facilitated by transglycosylation following the addition of phenyl-beta-D-thiocellobioside and cellobiose, thus demonstrating the catalytic competence of the trapped intermediate. The nucleophilic amino acid residue involved was identified as Glu280 by labeling the enzyme with tritiated inactivator, cleaving it into peptides and sequencing the radiolabeled peptide. Ion spray mass spectrometric analysis of the peptide confirmed the sequence and the mode of attachment of the sugar to the peptide. Alignment of all known related beta-1,4-glucanases showed that Glu280 is strictly conserved in family A enzymes, consistent with its key role in catalysis.

Characteristics of beta-lactoglobulin binding to the all-trans-retinal moiety covalently immobilized on Celite

All-trans-retinal was covalently immobilized on Celite and investigated as a bioselective adsorption matrix for beta-lactoglobulin. Two types of Celite supports were compared, indicating the best performance with 100/120 mesh, type R648. The R648 matrix yielded a high concentration (9.2 mumol/ml) of the ligand when the derivative was produced, and the derivatized matrix exhibited the best retention of beta-lactoglobulin. Binding of beta-lactoglobulin to the immobilized trans-retinal matrix is biospecific, but the affinity is dependent on pH and ionic strength. alpha-Lactalbumin is not bound to this bioselective adsorbant, so its elution was not retarded or affected by pH or buffer concentration. Affinity for beta-lactoglobulin was optimal at pH 5.14; a dissociation constant of 2.7 microM was obtained in .1 M buffer solutions. At pH 7.0, the affinity decreased 44-fold, and, below pH 3.5, no binding occurred. The estimated loading capacity based on chromatographic data was approximately 14 g/L (.75 mumol/ml) of support.

Indomethacin abolishes cerebral blood flow increase in response to acetazolamide-induced extracellular acidosis: a mechanism for its effect on hypercapnia?

Indomethacin is known to attenuate quite markedly the increase in CBF during hypercapnia. Hypercapnia is, in all likelihood, mediated by the acid shift at the level of the smooth muscle cells of the cerebral arterioles. We therefore investigated the effect of indomethacin on the CBF increase caused by acetazolamide (Az), a drug that induces brain extracellular acidosis, which triggers its effect on CBF. We compared the results to the inhibitory effect of indomethacin on the CBF increase during hypercapnia. Indomethacin but not diclofenac, another potent cyclooxygenase inhibitor, was found to block almost completely the CBF increase caused by Az-induced extracellular acidosis or by CO2, but it did not influence the CBF increase produced by sodium nitroprusside or papaverine. The results suggest that indomethacin exerts its action on CO2 reactivity by a nonprostaglandin-mediated mechanism that directly interferes with the regulation of cerebrovascular tone mediated by extracellular pH.

Regulation of hair follicle development: an in vitro model for hair follicle invasion of dermis and associated connective tissue remodeling

During embryonic development presumptive hair follicle cells of epithelial and mesenchymal origin are determined in defined body locations. This is followed by rapid proliferation of epithelial cells and associated penetration into the dermis in response to as yet undetermined signals. A collagen matrix culture system, which maintains the three-dimensional relationships of hair follicle cells to each other, was developed to study the regulation of the enlargement of immature hair follicles and the accompanying remodeling of the dermis. In studies with a heterogeneous dermis-derived preparation of murine hair follicles, ranging in size from the earliest down-growing budding cell mass to hair-forming follicles, we had previously shown that cell proliferation was stimulated by cholera toxin and epidermal growth factor, but only the epidermal growth factor-stimulated proliferation was accompanied by digestion of the collagen matrix due to release of collagenolytic enzymes. Further studies revealed that transforming growth factor-alpha also stimulated hair follicle cell proliferation and collagenase release. However, although transforming growth factor-beta inhibited the transforming growth factor-alpha-stimulated proliferation, it enhanced the release and activation of collagenases and other gelatin-degrading enzymes detectable by gelatin zymography. Stimulation of collagenolytic activity depended on the three-dimensional hair follicle structure and did not occur in monolayer cultures of hair follicle cells. Comparison of hair follicle buds with more developed dermis-derived hair follicles, plated at the same cell density (based on DNA content), suggested that a greater fraction of cells in the bud-stage follicle responded to the growth factors by release of collagenases. Possibly only the cells in the advancing portion of growing hair follicles that are closest to the dermal papilla cell cluster produce the collagenases in response to growth factors. To examine the participation of dermal papilla cells in collagenase release and activation, several immortalized rat whisker dermal papilla cell lines were co-cultured with mouse hair follicle buds. Co-culture resulted in a marked enlargement of follicles as well as activation of the 92-kDa type IV collagenase, produced by hair follicle buds, that correlated with ability of the dermal papilla cells to stimulate hair formation in grafts of hair follicle buds on nude mice. Dermal papilla cells cultured alone produced the 72-kDa type IV collagenase, which was also activated during co-culture with hair follicle buds. Thus, two activities, both relevant for hair follicle development, namely, cell proliferation and release and activation of collagenases, have been stimulated in immature hair follicle buds by either growth-factor supplementation or interaction with dermal papilla cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Cloning and characterization of subunits of the T-cell receptor and murine leukemia virus enhancer core-binding factor

Moloney murine leukemia virus causes thymic leukemias when injected into newborn mice. A major determinant of the thymic disease specificity of Moloney virus genetically maps to the conserved viral core motif in the Moloney virus enhancer. Point mutations introduced into the core site significantly shifted the disease specificity of the Moloney virus from thymic leukemia to erythroid leukemia (N.A. Speck, B. Renjifo, E. Golemis, T.N. Fredrickson, J.W. Hartley, and N. Hopkins, Genes Dev. 4:233-242, 1990). We previously reported the purification of core-binding factors (CBF) from calf thymus nuclei (S. Wang and N.A. Speck, Mol. Cell. Biol. 12:89-102, 1992). CBF binds to core sites in murine leukemia virus and T-cell receptor enhancers. Affinity-purified CBF contains multiple polypeptides. In this study, we sequenced five tryptic peptides from two of the bovine CBF proteins and isolated three cDNA clones from a mouse thymus cDNA library encoding three of the tryptic peptides from the bovine proteins. The cDNA clones, which we call CBF beta p22.0, CBF beta p21.5, and CBF beta p17.6, encode three highly related but distinct proteins with deduced molecular sizes of 22.0, 21.5, and 17.6 kDa that appear to be translated from multiply spliced mRNAs transcribed from the same gene. CBF beta p22.0, CBF beta p21.5, and CBF beta p17.6 do not by themselves bind the core site. However, CBF beta p22.0 and CBF beta p21.5 form a complex with DNA-binding CBF alpha subunits and as a result decrease the rate of dissociation of the CBF protein-DNA complex. Association of the CBF beta subunits does not extend the phosphate contacts in the binding site. We propose that CBF beta is a non-DNA-binding subunit of CBF and does not contact DNA directly.

Lrp, a major regulatory protein in Escherichia coli, bends DNA and can organize the assembly of a higher-order nucleoprotein structure

Lrp (Leucine-responsive regulatory protein) is a global regulatory protein that controls the expression of many operons in Escherichia coli. One of those operons, ilvIH, contains six Lrp binding sites located within a several hundred base pair region upstream of the promoter region. Analysis of the binding of Lrp to a set of circularly permuted DNA fragments from this region indicates that Lrp induces DNA bending. The results of DNase I footprinting experiments suggest that Lrp binding to this region facilitates the formation of a higher-order nucleoprotein structure. To define more precisely the degree of bending associated with Lrp binding, one or two binding sites were separately cloned into a pBend vector and analyzed. Lrp induced a bend of approximately 52 degrees upon binding to a single binding site, and the angle of bending is increased to at least 135 degrees when Lrp binds to two adjacent sites. Lrp-induced DNA bending, and a natural sequence-directed bend that exists within ilvIH DNA, may be architectural elements that facilitate the assembly of a nucleoprotein complex.

Prevalence and epidemiologic correlates of sexually transmitted Chlamydia trachomatis infection in a selected population

The incidence of Chlamydia trachomatis genitourinary infection was found by enzyme immunoassay antigen detection to be 10.0% in patients attending a sexually transmitted disease (STD) clinic, 3.0% in clients visiting an obstetrics-gynecology clinic, 20.8% in female prostitutes, and 1.3% in sexually active men. Predisposing factors for chlamydial infection were young age, multiple sexual partners, history of STDs, and coinfection with other STDs. Abnormal vaginal discharge and cervices in women, but not urethral manifestations in men, were significantly associated with chlamydial infection. Urethral gram stain had a certain value in identifying men infected with C. trachomatis.

Time course of spontaneous calcium-activated chloride currents in smooth muscle cells from the rabbit portal vein

1. The time course of spontaneous calcium-activated chloride currents was studied with the perforated patch technique in freshly dispersed smooth muscle cells from the rabbit portal vein. 2. In potassium-containing solutions the spontaneous transient outward current (STOC, a calcium-activated potassium current) was more commonly recorded than spontaneous transient inward currents (STICs, a calcium-activated chloride current). In addition the duration of STOCs was much briefer (about 100 ms) than the duration of STICs (about 400 ms). 3. The decay of STICs could be described by a single exponential but the STOC decay appeared to be more complex. The decay time constant of STICs was not determined significantly by amplitude. 4. The time constant of decay of STICs (tau) was 86 ms at -50 mV and was increased by depolarization. Between -90 and +50 mV the relationship between tau and membrane potential was exponential and tau changed e-fold for a change of membrane potential of 120 mV. 5. The I-V relationship of STIC amplitude was linear between -10 and +50 mV but at more negative potentials the chord conductance was reduced and the I-V relationship exhibited negative slope conductance between -50 and -90 mV. 6. There was good agreement between the STIC tau values and the exponential relaxations to voltage steps evoked during caffeine-induced calcium-activated chloride currents. 7. In the presence of the chloride channel blocking agent anthracene-9-carboxylic acid the STIC amplitude was reduced and tau was increased. This effect was voltage dependent with a much greater effect at positive potentials. 8. The evidence suggests that the decay of STICs represents closure of chloride channels and tau approximates to the channel mean open time.

Determination of 5,10,15,20-tetra-(m-hydroxyphenyl)chlorin in tissues by high performance liquid chromatography

A procedure for the extraction and high performance liquid chromatographic (HPLC) determination of the photodynamic therapeutic agent 5,10,15,20-tetra(m-hydroxyphenyl)chlorin in human, rat and mouse tissues following intravenous administration of the drug is described. The tissue (tumour, skin, muscle and liver) was homogenized and extracted into a mixture of methanol:dimethyl sulphoxide:water (32:8:1 by vol.) containing, 5,10,15,20-tetra(p-hydroxyphenyl)chlorin as the internal standard. The precipitated proteins were removed by centrifugation and the supernatant was separated by reversed phase HPLC on a Hypersil-ODS column with 77% (v/v) acetonitrile in 0.1% trifluoroacetic acid as the mobile phase. The solute was detected with high sensitivity and specificity by a UV-VIS detector set at 423 nm.

A monovalent ion-selective cation current activated by noradrenaline in smooth muscle cells of rabbit ear artery

Membrane currents were recorded with the perforated-patch method with a low-chloride (35 mM) pipette solution in isolated smooth muscle cells of the rabbit ear artery. At a holding potential of -50 mV in potassium-free conditions spontaneous inward single-channel currents were observed and noradrenaline evoked a noisy inward current, which appeared to be comprised of the spontaneous currents. The reversal potential (Vr) of the spontaneous channel and noradrenaline-induced current was not affected in anion-substitution experiments but Vr was altered when external Na+ was replaced with choline or TRIS. The relationship between clamp potential and spontaneous single-channel current amplitude was linear and the mean unitary conductance was 28 pS. Caffeine, which releases calcium from the sarcoplasmic reticulum, and the calcium ionophore ionomycin activated the cation current and also blocked the response to noradrenaline. Spontaneous channel current activity and the noradrenaline-induced current were blocked when external NaCl was replaced with 89 mM CaCl2. The response to noradrenaline was blocked by prazosin but was not affected by yohimbine and therefore the response is mediated by alpha 1-adrenoceptors. It is concluded that in rabbit ear artery smooth muscle cells there is a calcium-activated cation channel of 28 pS conductance, which is relatively impermeable to calcium but can be activated by noradrenaline.

Organization of Lrp-binding sites upstream of ilvIH in Salmonella typhimurium

Lrp, a major regulatory protein in Escherichia coli, controls the expression of numerous operons, including ilvIH. Lrp binds to six sites upstream of ilvIH, and Lrp binding is required for ilvIH expression. We show here that an Lrp-like protein is also present in Salmonella typhimurium. This protein can bind both E. coli and S. typhimurium ilvIH DNA, as can E. coli Lrp. Methidiumpropyl-EDTA footprinting studies were performed with purified E. coli Lrp and S. typhimurium ilvIH DNA. Six binding sites were defined, three of them being similar to corresponding sites in E. coli, and three being organized differently. A consensus derived from six S. typhimurium sites is compatible with that derived from a similar analysis of E. coli sequences.

Serine for glycine substitutions in type I collagen in two cases of type IV osteogenesis imperfecta (OI). Additional evidence for a regional model of OI pathophysiology

Serine for glycine substitutions in type I collagen have been described in seven cases of lethal type II osteogenesis imperfecta (OI), and six cases of nonlethal OI. We describe here two cases of moderately severe type IV OI with serine substitutions at alpha 1(I) Gly352 and alpha 2(I) Gly922, respectively. In both cases, G-->A point mutations were detected by RNase A cleavage of RNA/RNA and RNA/DNA hybrids. These cases extend the location for serine substitutions producing the moderately severe OI phenotype to the alpha 2(I) chain and the amino-terminal end of the alpha 1(I) chain. Their location supports a regional model of OI pathophysiology for serine substitutions. The proband with alpha 2(I) Gly922-->Ser has both normal and overmodified forms of both type I collagen chains. The overmodified form has delayed migration of all CNBr peptides. Helix thermal stability is decreased 4 degrees C. The fibroblast collagen protein and RNA of her unaffected parents are normal. However, the father was demonstrated to be a mosaic carrier using leukocyte DNA. The fibroblasts of the proband whose serine substitution is at alpha 1(I) Gly352 synthesize type I procollagen chains with delayed electrophoretic migration; normally migrating forms are difficult to detect. Only alpha 1(I) CB 8 displayed delayed migration. Helix thermal stability is reduced 2 degrees C. Parental genomic DNA was normal.

Nitric oxide does not act as a mediator coupling cerebral blood flow to neural activity following somatosensory stimuli in rats

The possible role of nitric oxide (NO) on vibrissa-stimulated increase of regional cerebral cerebral blood flow (rCBF) and cerebral metabolic rate of glucose (rCMRglu) was investigated in conscious Wistar rats by using an inhibitor of NO synthase, NG-nitro-L-arginine (NOLAG) at a concentration of 30 mg/kg. In vivo autoradiography distribution with 14C-iodoantipyrine and 14C-deoxyglucose in two separate series showed CBF of 174% of control and CMRglu of 196% of control in the primary sensory cortex opposite the stimulated side in saline treated control animals. Similar increases were found in NOLAG-treated animals. Furthermore, NOLAG did not change either basal CMRglu or CMRO2. The findings suggest, that NO is not involved in coupling flow to the increased metabolism accompanying physiological sensory stimuli.