An aromatic stacking interaction between subunits helps mediate DNA sequence specificity: operator site discrimination by phage lambda cI repressor

Sequence specific DNA binding by regulatory proteins provides the basis for regulation of initiation of transcription. A great deal of progress has been made toward understanding sequence specific recognition by individual protein subunits. An additional level of control that needs to be understood is that due to coupling between the subunits of oligomeric regulatory proteins. An example is the bacteriophage lambda cI repressor, a dimeric protein that regulates the lysogenic to lytic genetic switch of the phage. Two levels of specificity are critical to this regulation. First, like all transcriptional regulators, dimers distinguish operator from nonspecific DNA. Direct readout of the DNA sequence by the recognition helix is considered the well understood mechanism for this. However, differential affinity for O(R)1, O(R)2 and O(R)3 is equally critical to the switch because it mediates opposing regulation of divergent promoters. Site specificity at this second level is less well understood. Conformational adaptation by both the repressor and the different operators appears to be important. To evaluate how subunit-subunit interactions are involved in this process, we investigated the effects on both dimer stability and operator binding of amino acid substitutions at the contacts between the symmetrically related helices-5 in the dimer interface. Substitutions for Tyr88 alter dimer stability and greatly perturb differential operator affinity, but generally do not affect operator versus non-operator specificity. The pattern of these effects suggests that the geometry of the face-to-face aromatic stacking interaction between symmetrically related Tyr88 in each subunit, a group in the dimer interface but far removed from the DNA binding interface, plays a critical role in operator discrimination. Conformational changes in the tertiary structure of the subunits appears to be involved. By contrast, the significant effect of I84S substitution is to greatly decrease affinity for all three operators. Presumably, the altered packing of the dimer interface causes a quarternary structural change that moves the two helix-turn-helix motifs out of register with successive DNA major grooves.

Inositol phosphate responses in portal veins from portal hypertensive rats: receptor- and nonreceptor-mediated responses

BACKGROUND/AIMS

Venous hyporesponsiveness in portal hypertension has been reported previously by us. The present study was undertaken to investigate possible changes of phosphoinositide signal transduction pathway in the portal veins from portal hypertensive rats

METHODS

Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for measurement of [3H]inositol phosphate responses to both receptor- and nonreceptor-mediated stimuli.

RESULTS

Basal [3H]inositol phosphate formation was similar between the two groups. Both phenylephrine and angiotensin II stimulated [3H]inositol phosphate formation in portal veins, but the responses were attenuated in the portal hypertensive group. In contrast, the [3H]inositol phosphate formation by nonreceptor-mediated stimuli (GTP gamma S, NaF/AlCl3, and phospholipase C) was similar between the two groups.

CONCLUSION

Our results showed that the receptor-mediated [3H]inositol phosphate formation was attenuated, while the non-receptor-mediated formation was unaltered, in the portal vein from portal hypertensive rats.

The hemodynamic effects of AT-112, an analog of ketanserin, in portal hypertensive rats

A serotonin mechanism has been reported to contribute to the hyperdynamic circulation of portal hypertension. Different studies have demonstrated that serotonin antagonists decrease portal pressure in portal hypertensive patients and animals. The present study was undertaken to investigate the effect of AT-112, an analog of ketanserin, on portal hypertension induced by partial portal vein ligation in rats. Since ketanserin is known to possess alpha 1-adrenergic antagonistic activity, the effect of AT-112 was compared to that of prazosin. A single dose (prazosin 4.2 micrograms/kg, AT-112 1 mg/kg) was chosen to produce a similar hypotensive effect (-20 +/- 4% for prazosin and -24 +/- 4% for AT-112). At this dose, prazosin significantly decreased total peripheral resistance whereas AT-112 significantly decreased cardiac index and heart rate. Both agents significantly decreased the portal tributary blood flow and portal pressure. In rats receiving AT-112, a significant correlation was found between the magnitudes of decrease in cardiac index and the decrease in portal tributary blood flow. We also found that the magnitude of reduction in portal pressure was greater following AT-112 administration. This study suggested that AT-112 may have more beneficial hemodynamic effects than prazosin in portal hypertensive rats. Our results provide further support for the serotonergic mechanism in the pathogenesis of hyperdynamic circulation in portal hypertension.

Portal hypotensive effects of tetrandrine and verapamil in portal hypertensive rats

The portal hypotensive effects of tetrandrine and verapamil (both calcium-channel blockers) were assessed in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation in Sprague-Dawley rats. Both tetrandrine (4, 8, 16 and 24 mg kg-1) and verapamil (0.5, 1.0, 1.5 and 2.0 mg kg-1) induced dose-dependent decreases of portal venous pressure and mean arterial pressure after intravenous infusion. for example, infusion of tetrandrine (16 mg kg-1) induced a maximum reduction of portal venous pressure and mean arterial pressure approximately 1 min after the start of infusion. Portal venous pressure decreased from baseline (12.5 mmHg) to 10.0 mmHg, and mean arterial pressure from baseline (90 mmHg) to 80 mmHg. Heart rate decreased from 250 to 240 beats min-1. At 24 mg kg-1, tetrandrine reduced portal venous pressure and mean arterial pressure to 20.3 +/- 2.4% and 28.4 +/- 1.4% of baseline, respectively. Our results show that both tetrandrine and verapamil induce portal pressure reduction in portal hypertensive animals.

Chronic administration of octreotide increases vascular responsiveness in rats with portal hypertension

1. It has been reported that ortreotide partially corrects the hyperdynamic state in patients and animals with portal hypertension. The aim of the present study was to investigate whether chronic administration of octreotide can increase vascular responsiveness in rats with portal hypertension. 2. Portal hypertension was induced by partial portal vein ligation. Octreotide was given for 9 days subcutaneously (100 micrograms/kg every 12 h) starting 1 day before ligation. The aorta and mesenteric artery were then removed to study contraction after pressure recording. 3. Octreotide treatment significantly reduced portal pressure and plasma glucagon concentrations compared with the vehicle-treated group. Both phenylephrine and vasopressin induced concentration-dependent contractile responses in the aorta and mesenteric artery from both groups. The maximum contractile responses to phenylephrine and vasopressin in aorta and mesenteric artery were significantly greater in the octreotide-treated group than in the vehicle-treated group. The EC50 values for phenylephrine and vasopressin were significantly different in the aorta, but not in the mesenteric artery, but not in the mesenteric artery, between the two groups. In contrast, octreotide treatment did not alter the contractile responsiveness of arteries rom sham-operated rats. 4. These results show that, in rats with portal vein stenosis, octreotide increases arterial contractile responsiveness and reduces portal pressure.

Vascular hyporesponsiveness in aorta from portal hypertensive rats: possible sites of involvement

Vascular hyporesponsiveness in portal hypertension has been proposed to be due to postreceptor defect. The present study was aimed to investigate possible sites of involvement in such hyporesponsiveness. Portal hypertension was induced by partial portal vein ligation (PVL). Concentration-response curves to KCI and phenylephrine in both groups showed that the Emax values were significantly lower in the PVL group. The EC50 values were not different between the two groups. In Ca++ free condition, phenylephrine induced a phasic contraction, which was significantly smaller in the aorta from PVL rats. Cumulative readdition of CaCl2 (1.0-2.5 mM) induced tension increases, which were all significantly lower in the PVL group. Basal contents of [3H]inositol phosphates in the aorta were similar between the two groups. Phenylephrine induced concentration-dependent increase of [3H]inositol phosphates in the aorta from both groups. The responses at 10(-8), 10(-7), 10(-6) and 10(-5) M were significantly smaller in the PVL group than in the sham-operated group. Both okadaic acid and phorbol 12,13-dibutyrate induced slowly developing contractile responses in the aorta. The responses were similar between the two groups at all time points. Our results suggested that in the aorta from PVL rats, vascular hyporesponsiveness was observed, together with decreased contractile responses due to: voltage- and receptor-dependent calcium influx as well as intracellular calcium release, and decreased receptor-coupled inositol phosphate formation. Contractile responses due to activation of protein kinase C or phosphatase inhibition were not impaired.

Microwave-accelerated direct immunofluorescent staining for respiratory syncytial virus and influenza A virus

A microwave-accelerated direct immunofluorescence staining method which requires only 20 min from specimen receipt to interpretation is as effective as conventional methods for detecting respiratory syncytial virus and influenza A virus antigens in clinical specimens. The time required compares favorably with that for the less sensitive Abbott Test Pack RSV.

Hyperglucagonaemia in cirrhotic patients and its relationship to the severity of cirrhosis and haemodynamic values

Plasma glucagon concentrations were measured in 160 cirrhotic patients (Pugh's grade A in 52 patients, Pugh's grade B in 64 patients and Pugh's grade C in 44 patients). These values were compared with plasma glucagon concentrations in 57 age and sex-matched healthy subjects. Systemic and portal haemodynamic measurements, effective renal plasma flow and creatinine clearance were recorded for each patient. Plasma glucagon levels were significantly increased in cirrhotic patients compared with healthy subjects. In addition, plasma glucagon levels were higher in cirrhotic patients with ascites than in those without ascites and were increased in relation to the severity of cirrhosis as assessed by Pugh's score. Multiple linear regression found that only Child-Pugh's score was estimated to be an independent predictor of hyperglucagonaemia in cirrhotic patients. However, in patients with different degrees of oesophageal varices and in patients without oesophageal varices, plasma glucagon concentrations were no different among the different groups of patients, but were still higher than plasma glucagon concentrations in healthy subjects. In contrast, plasma glucagon levels were negatively correlated with mean arterial pressure and systemic vascular resistance. The results of the present study suggest that impairment of liver function plays, in part, a role in increased plasma glucagon levels observed in patients with cirrhosis. In addition, these data support the hypothesis that hyperglucagonaemia may contribute, at least in part, to the pathogenesis of peripheral arterial vasodilatation in cirrhosis with portal hypertension.

Effect of selection for size of testes in boars on semen and testis traits

The objective of this study was to evaluate the effects of selection for increased size of testes on semen and testis characteristics. Boars from a line selected for increased size of testes at 150 d of age (TS, n = 25) and a randomly selected control line (C, n = 18) were used. Semen was collected three times per week for 3 wk (TRT1) then daily for 3 wk (TRT2) beginning when boar age averaged 276 d. It was followed by a 4-wk period of one collection per week and then the TRT1-TRT2 sequence was repeated. After 64 collections, boars were castrated and testes were evaluated for sperm numbers. Volume of semen, percentage of motile sperm cells, and percentage of abnormal cells in the semen did not differ (P > .05) between lines. Concentration of sperm cells in the semen was greater for TS boars at TRT 1 (35.0 million cells/mL, P < .10) and TRT 2 (29.5 million cells/mL, P < .01). Number of sperm cells per ejaculate was greater for TS boars (6.1 and 4.3 billion cells for TRT 1 and TRT 2, respectively; P < .05). Percentage of abnormal cells was less (P < .05) for boars at the younger ages. Concentration of sperm cells was 16 to 18 million cells/mL semen greater (P < .05) at the older ages. Significant differences in the shapes of the response curves with increasing collection number across lines and ages were found. These differences were small and not considered to be important. Line differences in testicular and epididymal sperm numbers and in daily sperm production were consistent with differences in semen traits. Repeatabilities of semen traits were between .16 and .74. Selection for increased size of testes can be used to improve the reproductive capacity of boars used for artificial insemination.

Effects of long-term administration of octreotide in portal vein-stenosed rats

The hemodynamic effects of long-term administration of octreotide in portal hypertension has not been established. In addition, whether long-term octreotide treatment prevents the development of portosystemic shunts has not yet been evaluated. Hence, the current study was undertaken to evaluate the effects of long-term administration of octreotide in rats with portal vein stenosis. Immediately after portal vein stenosis or sham operation, rats were given either a long-term octreotide administration of 100 micrograms/kg or a placebo every 12 hours by subcutaneous injection for 14 consecutive days. Systemic hemodynamics and regional blood flows, degree of mesenteric-systemic shunts, and plasma glucagon concentrations were measured after the final dose of octreotide or placebo. A fifth group of portal vein-stenosed rats received hemodynamic and plasma glucagon measurements after 1-day octreotide treatment given at 14 days after surgery. Long-term octreotide treatment modified the hyperdynamic circulation without affecting the degree of mesenteric-systemic shunts, and 1-day octreotide treatment decreased portal tributary blood flow without affecting the portal pressure, systemic hemodynamics, and degree of mesenteric-systemic shunts. Plasma glucagon levels were decreased in portal vein-stenosed rats receiving either long-term or 1-day octreodtide compared with rats receiving placebo. In contrast, chronic octreotide treatment did not affect any of the hemodynamic values or plasma glucagon levels in sham-operated rats. In conclusion, long-term administration of octreotide modified in part the development of portal hypertension and hyperdynamic circulation in portal vein-stenosed rats without affecting the degree of mesenteric-systemic shunts.

Decreased vascular reactivity of portal vein in rats with portal hypertension

BACKGROUND/AIMS

Vascular hyporesponsiveness in portal hypertension is well documented in the arterial tissue. The present study aimed to investigate the possible changes in the portal vein from portal hypertensive rats.

METHODS

Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for contractile study and measurement of cAMP, cGMP and [Ca2+]i.

RESULTS

In vitro tension preparation showed a decreased maximum response to norepinephrine in portal vein of portal vein ligated rats (38.3 +/- 4.1 vs. 23.4 +/- 1.5 mN/mm2). The pA2 values of WB4101 and yohimbine (alpha1- and alpha2-adrenoceptor antagonist, respectively) were not different between the two groups. Tissue cAMP (14.4 +/- 0.9 vs. 12.2 +/- 0.7 pmol/mg protein), but not cGMP, content was increased and intracellular calcium [Ca2+]i levels (247 +/- 9 vs. 281 +/- 13 nM) were decreased in portal vein ligated rats.

CONCLUSIONS

These results showed that in portal vein from portal vein ligated rats, vascular hyporesponsiveness and an increase in basal cAMP content and a decrease in basal [Ca2+]i were observed.

[Research progress in lipoprotein (a): aspects of biochemistry and molecular biology]

Lipoprotein (a) (Lp(a)) is a LDL-like lipoprotein with an additional highly polymorphic glycoprotein--apolipoprotein (a) (apo(a)). Apo(a) bears great homology with plasminogen. Lp(a) is synthesized by liver and its degradation may be carried out by a nonspecific process. Apo(a) isoform size and plasma Lp(a) levels are mainly determined by apo(a) gene. Lp(a) can easily be deposited in arterial wall. It promotes growth of smooth muscle cells and inhibits fibrinolysis. These could be the mechanisms by which Lp(a) accelerates atherosclerosis and thrombosis. The physiological role of Lp(a) has not been clearly understood.

Induction of c-jun protooncogene expression by hydrogen peroxide through hydroxyl radical generation and p60SRC tyrosine kinase activation

The mechanisms of signal transduction of c-jun induction by hydrogen peroxide are elucidated in NIH3T3 cells by using trapping agents of hydroxyl free radical or inhibitors of various protein kinases. Pre-treatment of the cell with hydroxyl radical scavenger dimethyl sulfoxide (DMSO) abolishes the H2O2-induced c-jun expression. Hydroxyl radical generation can be detected and quantified in cells treated sequentially with DMSO and H2O2 for 30 min respectively by methane sulfinic acid (MSA) production, especially that from particulate fraction. Induction of c-jun by H2O2 is also dramatically reduced by pretreating the cells with biological antioxidant vit. E. Protein tyrosine kinase activity of membrane fraction is induced by H2O2 within 5 to 10 min, which can be prevented by DMSO pre-treatment. Inhibitor of non-receptor type tyrosine kinase, herbimycin A, has inhibitory effect on H2O2-induced c-jun expression while the inhibitor of receptor type tyrosine kinase, tyrphostin 23 or inhibitor of cyclic AMP dependent protein kinase, KT 5720, has not. TPA pre-treatment that depletes protein kinase C (PKC) has no influence on the c-jun induction by H2O2. Our results suggest that the highly reactive species HO is generated after H2O2 enter cells and mediate the signal responses of H2O2 including c-jun induction and the activation of p60src tyrosine kinase might be one of the molecular events associated with the c-jun induction pathway.

Inhibitions of protein kinase C and proto-oncogene expressions in NIH 3T3 cells by apigenin

Apigenin, a low-toxic and non-mutagenic plant flavonoid, suppresses 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-mediated tumour promotion of mouse skin. TPA has the ability to activate protein kinase C (PKC) and induce proto-oncogene expression. Our study shows that apigenin inhibits PKC by competing with ATP, and exhibits an IC50 value of 10 +/- 0.5 microM. Apigenin also reduces the level of TPA-stimulated phosphorylation of cellular proteins. Of the protein tyrosine kinases tested, the fibroblast growth factor (FGF) receptor was most strongly affected by apigenin (IC50 20 microM), and pp60v-src most weakly affected (IC50 > 200 microM). Treatment of NIH 3T3 cells with 100 ng/ml TPA and 10, 50 and 100 microM apigenin resulted in 50, 80 and 100% suppression of TPA-induced C-JUN expression, respectively. Treatment of TPA with 10 microM apigenin inhibited TPA-induced C-FOS expression. TPA-stimulated cell growth was suppressed by 25 microM apigenin. Our results provide some evidence for understanding apigenin's inhibitory effects of TPA-mediated tumour promotion.

Allergens of Bipolaris species

Skin prick tests done previously revealed a significantly higher percentage of sensitization to an extract of Bipolaris sp. among atopic individuals (34/147, 23.1%) compared to non-atopic individuals. Bipolaris-specific IgE levels were quantified in sera from a representative group of 38 individuals using the Fluorescence Allergosorbent Test (FAST). Result obtained by FAST were found to be comparable to the skin prick test results (r2 = 0.60, p < 0.001 for IgE levels vs wheal sizes; r2 = 0.44, p < 0.001 for IgE levels vs erythema sizes). Characterisation of the extract's allergenic component by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed 28 protein bands with molecular weights (MW) ranging from 11 kDa to above 100 kDa. Immunoblotting with sera of 10 Bipolaris-sensitive (skin prick test, 3 +) individuals showed that Bipolaris spore extract contained at least 4 IgE binding proteins (MW 11-13 kDa, 16-17 kDa, 20-22 kDa and 36 kDa). All 10 sera reacted to the protein at MW 20-22 kDa, 2 sera with MW 11-13 kDa, 3 sera with 16-17 kDa and 6 sera with 36 kDa. This study has thus demonstrated that spores of Bipolaris sp. contain allergenic components which may elicit IgE-mediated reactions.

Fructus aurantii reduced portal pressure in portal hypertensive rats

The purpose of this study was to investigate the effects of Fructus Aurantii (the unripe fruits of Citrus aurantium L.) on portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated (Sham) rats served as controls. Hemodynamic and in vitro contractile studies were performed at 14 days after surgery. Both the aqueous extract of Fructus Aurantii and synephrine, one of its purified principles with pressor activity, were infused into the conscious PVL and Sham rats via a syringe pump. Fructus Aurantii (1.25, 2.5, & 5.0 mg/kg/min) dose-dependently reduced portal pressure in PVL and Sham rats, with the percentage change in portal pressure more pronounced in PVL rats. Mean arterial pressure was dose-dependently elevated by Fructus Aurantii. Synephrine (0.095, 0.19, & 0.38 mg/kg/min) also dose-dependently reduced portal pressure and elevated mean arterial pressure in PVL and Sham rats. Fructus Aurantii (2.8-280 micrograms/ml) induced dose-dependent contractile responses mainly in aorta and mesenteric artery, but little response in portal vein. The results showed that Fructus Aurantii infusion reduced portal pressure, possibly by way of arterial vasoconstriction.

Multiband wavelength-division demultiplexing with a cascaded substrate-mode grating structure

A multiband wavelength-division-demultiplexing (WDDM) structure, which incorporates cascaded substrate-mode holograms, is presented. The method can be used to design a WDDM device that consists of two or more layers of fundamental units (i.e., substrate-mode holograms). The fundamental unit is based on a diffracted grating and a substrate that include angular dispersion, wavelength bandwidth, and total internal reflection, which can be used to separate optical signals of different wavelengths. We have designed and built a multiband WDDM device, incorporating cascaded substrate-mode holograms in dichromated gelatin.

Endothelium-dependent vasorelaxant effect of trilinolein: mediated by nitric oxide and cyclic GMP

At concentrations ranged from 0.1 nM to 1 microM, trilinolein concentration-dependently relaxed the phenylephrine-induced constriction of isolated rat aorta. Concentration-response curves for the interaction between trilinolein and phenylephrine showed that trilinolein was unlikely a competitive antagonist of phenylephrine. The vasorelaxant effect of trilinolein was dependent on the presence of intact endothelium. Both NG-nitro-L-arginine methyl ester and methylene blue antagonized this vasorelaxant effect. L-arginine partially reversed the effect of L-NAME on trilinolein. Linoleic acid had no vasorelaxant effect. We concluded that trilinolein is an endothelium dependent vasorelaxant and the underlying mechanism could be a stimulation of the nitric oxide and cyclic GMP pathway.

The contribution of respiratory viruses to severe exacerbations of asthma in adults

Viral infections are known to be associated with severe exacerbations of asthma in children. In contrast, there is limited data that viral infections evoke acute episodes of asthma that require emergency care in adults. To determine the role of viral infections in exacerbations of asthma in adults, we examined 33 patients who presented to the emergency room with 35 exacerbations of asthma between September 1990 and March 1991 for the presence of a viral infection. A nasal swab was obtained for virus isolation by culture and rapid antigen detection by fluorescent staining. In 16 patients, serum was collected at initial presentation and 3 to 4 weeks later for acute and convalescent viral antibody titers. All patients had acute episodes of asthma ascertained by medical history and physical examination. About 56% of the patients with asthma exacerbations had symptoms suggestive of viral illness. Rapid antigen detection and viral cultures for influenza A and B, parainfluenza-1, 2, 3, respiratory syncytial virus, adenovirus, and rhinovirus were negative on all patients. Likewise, in all 16 patients tested, acute and convalescent serologic studies did not show a significant rise in titer by complement fixation test. Thus, despite symptoms consistent with viral infection, viral pathogens could not be shown by current virologic techniques. This study suggests that viral infection may not be as prevalent a precipitate of asthma in adults requiring emergency room treatment as is generally thought.

Polarization-independent optical switch composed of holographic optical elements

A novel 2 x 2 polarization-independent optical switch with holographic optical elements is proposed. The switch consists of an electro-optic half-wave plate sandwiched between two pairs of holographic polarization beam splitters. Normally incident input and output couplings of this compact and lightweight device provide better flexibility and easier alignment for system applications.

Role of basic residues in the proteolytic activation of Sendai virus fusion glycoprotein

Cleavage activation of the Sendai virus (Fushimi strain) fusion (F) protein was analyzed by site-directed mutagenesis of the amino acids proximal to the highly conserved fusion peptide. In addition, the functional properties of the wild-type and mutant proteins were examined to determine their ability to elicit the formation of syncytia when co-expressed with the hemagglutinin-neuraminidase (HN) glycoprotein. Viral genes were expressed from recombinant T7 transcription vectors (pT7/T3 plasmids) containing F or HN genes, after transfection into cells previously infected with a recombinant vaccinia virus expressing T7 RNA polymerase (vTF7-3). The wild-type F protein sequence (112VPQSRF) which contains a monobasic cleavage activation site was altered to include a tribasic, 112VPRKRF (mB3), or a pentabasic sequence, 112RRRKRF (mB5) adjacent to the fusion peptide. Although addition of basic residues to the normal protein sequence resulted in enhanced cleavage activation of the mB3 and mB5 proteins, only the mB5 protein was able to induce syncytia formation in CV-1 or HeLa T4 cells. Further analysis by the introduction of acidic residues upstream of the cleavage activation site was performed to determine whether increased hydrophilicity of the surrounding residues might contribute to cleavage activation. The mutants examined, mAcB1 (104NDDEENAGVPQSRF), mAcB3 (104NDDEENAGVPRKRF), and mAcB5 (104NDDEENAGRRRKRF) all contained DEE in replacement for the wild-type TTQ sequence (104NDTTQNAGVPQSRF). Analysis showed that only mAcB3 was efficiently cleaved by the endogenous cellular proteases, while mAcB1 was minimally cleaved, and mAcB5 not at all. Consequently, only the mAcB3 mutant was able to support fusion of CV-1 or HeLa T4 cells when co-expressed with HN.

Decreased vascular contractile and inositol phosphate responses in portal hypertensive rats

The purpose of this study was to investigate the vascular contractile and inositol phosphate responses in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated rats served as controls. Pressures, vasoconstrictor responses, and inositol phosphate responses were determined at 14 days after surgery. The portal venous pressure was significantly higher, while systemic arterial pressure and heart rate were lower, in PVL rats. Dose-dependent contractile responses were observed for both norepinephrine (1 x 10(-8) - 3 x 10(-6) M) and vasopressin (3 x 10(-10) - 3 x 10(-8) M) in the tail artery of both groups. The contractile response to norepinephrine was significantly decreased in PVL rats compared with controls at all doses. The contractile response to vasopressin was significantly decreased in PVL rats at higher doses. After myo-[3H]inositol incorporation in tail artery, the levels of 3H-labelled phosphatidylinositols (cpm/mg) were similar between the two groups. Norepinephrine (10(-7) - 10(-5) M) and vasopressin (10(-10) - 10(-8) M) dose dependently stimulated the 3H-labelled inositol phosphate production in the tail artery of both PVL and sham-operated rats. However, the response was significantly lower in PVL rats. The results suggested that the attenuation of vascular contractile responses in portal hypertension was reflected in the phosphoinositide messenger system.

Change in vascular cAMP and cGMP contents in portal hypertensive rats

The purpose of this study was to investigate the possible changes of cyclic nucleotide contents in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated rats served as controls. Hemodynamic and cyclic nucleotide measurements were performed at 14 days after surgery. The portal venous pressure was significantly higher, while systemic arterial pressure and heart rate were lower in PVL rats than those in controls. Basal cAMP (PVL, 10.91 +/- 0.98, vs. sham, 8.08 +/- 0.81 pmol/mg protein) and cGMP (PVL, 0.91 +/- 0.12, vs. sham, 0.59 +/- 0.05 pmol/mg protein) contents in the tail artery were significantly higher in PVL rats. Isobutyryl methylxanthine (10(-5) M), a nonspecific phosphodiesterase inhibitor, exerted similarly stimulating effects on the tissue cGMP (PVL, 158 +/- 10, vs. sham, 178 +/- 20%) and cGMP (295 +/- 28 vs. 316 +/- 71%) levels in both PVL and control rats; so did forskolin (10(-6) M) on the cAMP (184 +/- 20 vs. 197 +/- 66%) content in both groups. Our results showed that the arterial cAMP and cGMP contents were higher in PVL rats, which may contribute to the reduction of peripheral resistance in portal hypertension.

Characterization of human parainfluenza virus type 2 RNAs in infected cells and by in vitro synthesis

The RNA species synthesized in HPIV-2 infected CV-1 cells were identified and characterized. The largest RNA of approximately 5.5 x 10(6) in molecular weight (MW) based on electrophoretic mobility, was identified as the genomic RNA. The other small RNA species of MWs 2.4 x 10(6), 1.1 x 10(6), 0.77 x 10(6), 0.68 x 10(6) and 0.5 x 10(6) were identified as mRNAs. The five smallest RNAs were also synthesized in vitro and comigrated with RNAs synthesized in virus-infected cells. mRNAs synthesized both in vitro and in virus-infected cells were translated in vitro. NP, P, M and V proteins synthesized in vitro comigrated, when analyzed by SDS-PAGE, with the authentic proteins synthesized in virus-infected cells. Additionally, peptide mapping showed that the NP, P and M proteins synthesized in vitro were indistinguishable from their counterparts synthesized in infected cells. Analysis of the proteins from virions identified L, HN, NP, F (F1, F2), P, M and V proteins as virion structural proteins. Electrophoretic mobility of reduced and nonreduced F proteins was found to be different due to the conformational changes conferred by disulfide bonds.

Substrate-mode holographic polarization-division multi/demultiplexer for optical communications

Based on the diffractive properties of a transmission-type phase volume hologram, a new type of polarization-division multi/demultiplexer for optical communications is presented.

Inhibition of replication of human respiratory syncytial virus by 6-diazo-5-oxo-L-norleucine

The effect of 6-diazo-5-oxo-L-norleucine (L-DON), a glutamine analog, on RSV replication was studied. At a concentration of 0.01 mM L-DON, 99% of RSV replication in treated CV-1 cells was inhibited. At this concentration of L-DON, the level of cellular protein synthesis was identical to untreated control cells. Trypan blue staining revealed that all the cells remained viable even at concentrations of L-DON as high as 10 mM. In addition, L-DON added as late as 24 h post infection can effectively suppress viral replication. Analysis of viral mRNA levels by Northern blot revealed that secondary transcription and subsequent steps in the virus life cycle were inhibited. Immunoprecipitation of viral proteins from drug treated or untreated cultures showed that synthesis of all viral proteins was drastically reduced by L-DON, with a slightly greater inhibition of viral glycoproteins. Furthermore, immunofluorescent staining showed that drug treated cells expressed both F and N proteins and that F was inserted into the membrane as the native F protein.

[Local resection for the treatment of carcinoma of the papilla of Vater]

6 cases of local resection for the treatment of carcinoma of the papilla of Vater were reported. The average age was 63.8 years. All the patients were admitted with chief complaint of jaundice. The ill course was 1-2 months. The diagnosis was confirmed in 2 cases through endoscopic biopsy and in 4 by frozen section during surgery. The tumors were visualized with the diameter less than 2 cm. The survival time was related with pathological condition of the tumor. 1 of low differentiated and 1 of infiltrative adenocarcinoma were died of 16 and 20 months respectively after surgery. In 2 papillocarcinoma, 1 survived more than 5 years, another died of other cause after 28 months postoperatively. 1 of high differentiated carcinoma and 1 of mucinous carcinoma survived well after 29 and 46 months respectively. Local resection is not a real radical operation. It is only indicated for old patients with high-risk or severe concurrent diseases. They are not able to tolerated whipple procedure and tumors are small enough to be excised locally. A better survival rate would be expected. The operative technique was discussed in detail.

[Villous tumor of the duodenum]

8 cases of duodenal villous tumor were reported. A total of 11 tumors, with 2 in the bulb and 9 in the descending part, were excised. Malignant change was found in 4 cases (50%). Diagnosis could be made by using hypotonic duodenography and fibroscopy. The integral tumor should be examined by frozen section during operation, so as to determining the appropriate operation for satisfactory result. Postoperative follow up should be done periodically because of the possibility of recurrence after local excision.

Altered mitochondrial redox responses in gram negative septic shock in primates

Gram negative sepsis causes changes in oxygen supply-demand relationships. We have used a primate model of hyperdynamic gram negative sepsis produced by intravenous infusion of Escherichia coli (E. coli) to evaluate sepsis-induced alterations in mitochondrial oxidation-reduction (redox) state in muscle in vivo. The redox state of cytochrome a,a3, the terminal member of the intramitochondrial respiratory chain, was assessed in the intact forearm by near-infrared (NIR) spectroscopy. The muscle NIR data were compared to routine measures of oxygen delivery (DO2) and oxygen consumption (VO2). After E. coli infusion and fluid resuscitation, DO2 and VO2 showed minimal changes through 24 hr of sepsis. In contrast, changes in cytochrome a,a3 redox state evaluated by NIR occurred within a few hours and were progressive. Mitochondrial functional responses were correlated with structural changes observed on serial muscle biopsies. Gross morphological changes in muscle mitochondria were present in some animals as early as 12 hr, and, in most animals, by 24 hr. The morphologic changes were consistent with decreases in oxidative capacity as suggested by NIR spectroscopy. The NIR data also suggest that two mechanisms are operating to explain abnormalities in oxygen metabolism and mitochondrial function in lethal sepsis. These mechanisms include an early defect in oxygen provision to mitochondria that is followed by a progressive loss in functional cytochrome a,a3 in the muscle.

Polarization-selective volume holograms: general design

General design of polarization-selective volume holograms is discussed in detail. The required diffraction angles for these highly polarization-selective elements are calculated. An effective indexmodulation parameter is defined and used to calculate the required index-modulation value at any specified operating wavelength. Design examples of operating wavelengths at 780, 830, 1050, 1300, and 1550 nm are given. Highly polarization-selective substrate-mode grating pairs for 780-nm operation were fabricated to verify the idea. These elements are suitable for applications in optical switching networks and magneto-optic data storage systems.

Agonist desensitisation of alpha 1 adrenoceptors and endothelin-1 receptors coupled to phosphatidylinositol metabolism

Agonist desensitisation of responses coupled to phosphatidylinositol metabolism were studied. Responses mediated by two different agonists, endothelin-1 and noradrenaline were investigated. In vivo pressor responses were examined in conscious male New Zealand white rabbits, while effects on inositol phosphate formation were studied in rings of freshly isolated aorta and in cultured aortic vascular smooth muscle cells. No desensitisation of responses to noradrenaline were observed in vivo despite a 10-day infusion under conditions which cause desensitisation of alpha 2 and beta-adrenoceptor mediated responses. In contrast, responses to endothelin-1 were attenuated within 5 min of commencing endothelin-1 infusions. No reduction in noradrenaline stimulated inositol phosphate was observed in cultured vascular smooth muscle cells after pre-incubation with noradrenaline up to 10(-4) M, whereas with endothelin-1 pre-incubation a dose and time-related reduction in endothelin-1 stimulated inositol phosphate formation was observed. Thus, differences in the pattern of desensitisation of both pressor responses and phosphatidylinositol metabolism were observed for noradrenaline and endothelin-1 suggesting that the nature of the 2nd messenger involved in signal transduction is not the only determinant of agonist desensitisation. In addition, differences in the rate of desensitisation and sensitivity to endothelin-1, but not noradrenaline, were observed when responses in cultured cells were compared with in vivo responses or responses to freshly isolated tissues. These differences are discussed in relation to possible modifications of the endothelin receptor or its coupling to phosphatidylinositol metabolism during culture.

[SEM image analysis of endothelial cells of autogenous vein grafts]

The autogenous veins of 17 dogs were distended with 40kPa, 80kPa and 120kPa pressure prior to grafting to femoral arteries respectively. The sections were harvested immediately, and after 1 week, 4 and 16 weeks and inspected with SEM. The endothelial cells of grafted veins were studied with an image analysis system. The results showed that the desquamation extent of intimal layer correlated positively with pressure. 80 and 120kPa caused relatively severe damage to the endothelium, which was significantly different from that of control group (P < 0.05). We conclude that preimplantation distention of vein grafts should be employed with less than 80kPa pressure, and 120kPa can never be used in clinic, as it adversely affects the course of reendotheli alization. The distention did not make a notable impact to graft patency rate as demonstrated in this experiment.

[Evolution of biomechanical changes and microstructural components in autogenous vein grafts]

We evaluated the compliance characteristics of autogenous vein grafts clinically and experimentally. The image analysis instrument was applied in measuring the relative contents of elastin and collagen of the grafts. The results showed the consistent compliance mismatch between the vein graft and the host artery, but no definitive bearing on abnormal blood flow velocity waveform by the compliance mismatch. The compliance characteristics of the vein graft resembled these of the vein rather than those of the artery. The relative contents of elastin and collagen within the graft wall and the ratio of collagen to elastin (C/E) did not change significantly as a function of time. The vein graft and vein had the similar value of C/E, which was lower than that of the artery.

[Point mutation of K-ras gene in pancreatic carcinoma]

Direct sequencing using Taq enzyme was established for determination of point mutation of K-ras gene at codon 12 in 9 wax samples of pancreatic carcinoma (PC) and 1 of islet cell tumor. Point mutation occurred in 5 of 9 samples of PC and manifested two types of mutation, CCA-->CGA in 4 and CCA-->CAA in 1. The changes of amino acid included changes of glycine to alanine and glycine to valine. The causes of mutation frequency and the content differed from that of foreign reports were analysed in addition to the significance of determining point mutation of K-ras gene at codon 12.

Long-term results of surgical treatment for acute hemorrhagic necrotizing pancreatitis

Eighteen patients with acute hemorrhagic necrotizing pancreatitis who survived from operation were followed up for 12 to 43 months. Late complications including pancreatic external fistula, pseudocyst, hyperglycemia, etc were reviewed. The pancreatic juice was collected through endoscopic cannulation. The volume and HCO3- concentration of the pancreatic juice and three kinds of pancreatic enzymes were measured. The results demonstrated that inspite of anatomic abnormality or functional impairment of the pancreas, the pancreatic insufficiency rarely manifested to be marked because of the compensative ability of the viable exocrine pancreas.

[Portal high flow state in dogs]

To make an animal model of portal high blood flow, a retrograde portacaval shunt (PCS) was designed. A regular side-to-side PCS with large stoma was performed first, followed by the ligation of the vena cava just proximal to the anastomosis. Thus the whole amount of blood of the lower half body turned its flow into the portal system. Portal hypervolemic model was made in 11 dogs, The portal hemodynamics was studied by duplex before operation and 10 days, 20 days and 4 months after operation. In the 10th day the 20th day and the 4th month after operation, laparotomy was done again for observing FPP, portal collateral circulation, and liver biopsy. The portal high flow state was maintained constantly and FPP elevated in different degrees. The portal collateral circulation and the pathological change of the liver was not remarkable. The function of the liver was not damaged. The portal high flow state was proved not to cause real clinical portal hypertension, while the elevation of portal resistance was the important initiating factor for formation of portal hypertension.

Characterization of the in vitro system for the synthesis of mRNA from human respiratory syncytial virus

An in vitro transcription system for human respiratory syncytial virus (RSV) is described. Purified viral nucleocapsid (RNP) isolated from virus-infected cells was shown to support transcription of all 10 genes encoded by the virus as determined by Northern blot hybridization. The mRNAs synthesized were polyadenylated and comigrated with the corresponding mRNAs synthesized in virus-infected cells when analyzed in agarose-urea gel electrophoresis. The in vitro-synthesized mRNAs are functional as determined by their capacity to synthesize protein in vitro. The transcriptional reaction was significantly stimulated by the uninfected host cell lysate, indicating a requirement of host factor(s) in mRNA synthesis. Preliminary results suggest that cellular actin is involved in this process.

Rapid detection of herpes simplex virus in culture by in situ hybridization

Detection of herpes simplex virus (HSV) by a newly developed HSV-DNA in situ hybridization (ISH) technique (Diagnostic Hybrids, Inc., Athens, OH, USA) was compared with a reference standard that combines observation for cytopathic effect in shell vial cultures with subsequent identification of virus by staining with fluorescein-labeled HSV-specific monoclonal antibody. The new technique utilizes a probe consisting of an alkaline phosphatase direct labeled, cloned, single stranded DNA fragment that is common to HSV-1 and HSV-2. Both methods include enhancement of infection by centrifugation. In concurrent testing of 98 freshly collected specimens, HSV was detected in 17 by culture and 16 by ISH. In testing of 57 frozen positive specimens, HSV was detected in 54 by culture and 53 by ISH. Of the total isolates, 22 were HSV-1 and 49 were HSV-2. HSV was detected after 24 hrs of incubation by the DNA probe technique. Using the shell vial method as a reference standard, the new HSV-DNA ISH method had a sensitivity of 97.2%, specificity of 100%, positive predictive value of 100%, and a negative predictive value of 97.7%. HSV-DNA ISH appears to be a practical, sensitive, and specific technique for detection of HSV.

Spectral enhancement of proteins: biological incorporation and fluorescence characterization of 5-hydroxytryptophan in bacteriophage lambda cI repressor

We have used a tryptophan-requiring Escherichia coli auxotroph to replace the three tryptophan residues of lambda cI repressor with 5-hydroxy-L-tryptophan (5-OHTrp). By using a nonleaky promoter, we have achieved > 95% replacement of tryptophan in the repressor. We show that the absorbance and fluorescence properties of 5-OHTrp-lambda cI are clearly distinct from lambda cI repressor and that the fluorescence of 5-OHTrp-lambda cI repressor can be observed selectively in the presence of exogenous tryptophan. We also show that the 5-OHTrp-lambda cI repressor functional properties, as assessed by measurement of binding constants for self-association and for association to operator DNA, and structural properties, as assessed by fluorescence, are indistinguishable from the native repressor. Based on these results, we anticipate that the availability of spectrally enhanced proteins will significantly enhance the utility of both fluorescence and phosphorescence spectroscopies to study protein structure and function in complex interacting systems.

Intercellular adhesion molecule-1 (ICAM-1)-dependent and ICAM-1-independent adhesive interactions between polymorphonuclear leukocytes and human airway epithelial cells infected with parainfluenza virus type 2

Acute respiratory virus infections are often associated with an early influx of neutrophils (PMN) into the airways. Maximal cytoxic injury by PMN depends on tight cell-cell adhesion. Infection of some cell types by respiratory and other viruses has been shown to increase PMN adhesion to these cells by undefined mechanisms. We studied adhesion by human PMN to monolayers of primary (1 degree) human tracheal epithelial cells (TEC) or an immortalized cell line derived from human TEC, 9HTEo-, that had been infected with parainfluenza virus type 2 (PiV2). PMN adhesion to uninfected 1 degree TEC was very low (< 5%), but PMN adhesion to PiV2-infected 1 degree TEC was greatly increased (89 +/- 7%). PMN adhesion to 9HTEo- cells was 47 +/- 6%, but increased, 87 +/- 8%, for PiV2-infected 9HTEo- cells. Surface intercellular adhesion molecule-1 (ICAM-1) expression on 1 degree TEC, as determined by immunofluorescence flow cytometry, was relatively low (23 fluorescence units) but doubled by 24 h after PiV2 infection and tripled by 48 h. The 9HTEo- cells constitutively expressed higher levels of surface ICAM-1 (120 units) which did not increase with PiV2 infection. Treatment of non-PiV2-infected 9HTEo- cells with mAb (R6.5) to ICAM-1 reduced PMN adhesion to these cells from 47 +/- 8 to 23 +/- 5%. Identical mAb treatment of either 1 degree TEC or 9HTEo- cells infected with PiV2 had no significant effect on PMN adhesion. Treatment of the PMN with mAb against CD11a, CD11b, or CD18 markedly reduced PMN adhesion to PiV2-infected 1 degree TEC and 9HTEo- cells. We conclude that PiV2 infection of human TEC causes a marked increase in their adhesive interactions with PMN by inducing increased surface expression of both ICAM-1 and one or more, as yet uncharacterized, non-ICAM-1 adhesion molecules that function as counter-receptors for CD11/CD18 on PMN. These mechanisms of adhesion may play a role in epithelial damage during acute respiratory virus infections.

Intercellular adhesion molecule-1 (ICAM-1)-dependent and ICAM-1-independent adhesive interactions between polymorphonuclear leukocytes and human airway epithelial cells infected with parainfluenza virus type 2

Acute respiratory virus infections are often associated with an early influx of neutrophils (PMN) into the airways. Maximal cytoxic injury by PMN depends on tight cell-cell adhesion. Infection of some cell types by respiratory and other viruses has been shown to increase PMN adhesion to these cells by undefined mechanisms. We studied adhesion by human PMN to monolayers of primary (1 degree) human tracheal epithelial cells (TEC) or an immortalized cell line derived from human TEC, 9HTEo-, that had been infected with parainfluenza virus type 2 (PiV2). PMN adhesion to uninfected 1 degree TEC was very low (&lt; 5%), but PMN adhesion to PiV2-infected 1 degree TEC was greatly increased (89 +/- 7%). PMN adhesion to 9HTEo- cells was 47 +/- 6%, but increased, 87 +/- 8%, for PiV2-infected 9HTEo- cells. Surface intercellular adhesion molecule-1 (ICAM-1) expression on 1 degree TEC, as determined by immunofluorescence flow cytometry, was relatively low (23 fluorescence units) but doubled by 24 h after PiV2 infection and tripled by 48 h. The 9HTEo- cells constitutively expressed higher levels of surface ICAM-1 (120 units) which did not increase with PiV2 infection. Treatment of non-PiV2-infected 9HTEo- cells with mAb (R6.5) to ICAM-1 reduced PMN adhesion to these cells from 47 +/- 8 to 23 +/- 5%. Identical mAb treatment of either 1 degree TEC or 9HTEo- cells infected with PiV2 had no significant effect on PMN adhesion. Treatment of the PMN with mAb against CD11a, CD11b, or CD18 markedly reduced PMN adhesion to PiV2-infected 1 degree TEC and 9HTEo- cells. We conclude that PiV2 infection of human TEC causes a marked increase in their adhesive interactions with PMN by inducing increased surface expression of both ICAM-1 and one or more, as yet uncharacterized, non-ICAM-1 adhesion molecules that function as counter-receptors for CD11/CD18 on PMN. These mechanisms of adhesion may play a role in epithelial damage during acute respiratory virus infections.

Wavelength-division-multiplexing and -demultiplexing by using a substratemode grating pair

We present theoretical and experimental studies of a novel substrate-mode grating pair structure for wavelength-division-multiplexing/demultiplexing applications. Normally incident coupling and on-axis output imaging with this device provide easier alignment with coupled optical fibers. We have designed and fabricated wavelength-division-multiplexing devices that are implemented by polarization-insensitive high-efficiency (> 85%) substrate-mode holograms. Three-channel demultiplexing experiments have also been successfully demonstrated with the limited available wavelength range of our diode-laser system.

Effects of endothelin upon blood pressure in normotensive rabbits and in perinephritis hypertension

AIMS

The effects of endothelin upon blood pressure were investigated in normotensive and hypertensive rabbits.

METHODS

Endothelin was injected intravenously into conscious animals and blood pressure was monitored. Groups were pretreated with vehicle, calcium antagonists, indomethacin to block prostaglandin release, or NG-nitro-L-arginine methyl ester (L-NAME) to block endothelium-derived relaxing factor (EDRF) production in order to study the mechanisms of action of endothelin in normotensive and hypertensive animals.

RESULTS

Intravenous endothelin caused a rapid depressor response lasting less than 1 min followed by a prolonged pressor response. Calcium antagonists attenuated this pressor response. Hypertensive animals showed a greater sensitivity to calcium antagonists than normotensives. High concentrations of calcium antagonists abolished the pressor response, revealing a more prolonged depressor response lasting up to 5 min. Indomethacin pretreatment caused an apparent dose-related increase in pressor responses in all animals. L-NAME pretreatment enhanced responses in normotensives but caused no change or a decrease in these responses in hypertensive animals. Neither calcium antagonists, indomethacin or L-NAME modified the initial depressor response to endothelin. However when given together with nifedipine infusion, which abolished the pressor response, indomethacin and L-NAME decreased the duration of the depressor response.

CONCLUSIONS

In conscious rabbits extracellular calcium influx is important in mediating pressor responses to endothelin. In normotensive rabbits endothelin apparently causes release of prostaglandin and EDRF modifying responses. In hypertensive rabbits, a role for prostaglandins but not EDRF was observed in modulating responses to endothelin. Thus, the measured response to endothelin is the sum of a number of effects, the relative importance of which may be altered in pathological conditions.