Analysis of two gene regions involved in the expression of the imipenem-specific, outer membrane porin protein OprD of Pseudomonas aeruginosa

A Tn501 mutant of Pseudomonas aeruginosa resistant to imipenem and lacking the imipenem-specific outer membrane porin protein OprD was isolated. The mutation could be complemented to imipenem susceptibility and OprD-sufficiency by a cloned 6-kb EcoRI-PstI fragment of DNA from the region of chromosome of the wild-type strain surrounding the site of Tn501 insertion. However, this fragment did not contain the oprD structural gene as judged by its inability to hybridize with an oligonucleotide corresponding to the N-terminal amino acid sequence of OprD. DNA sequencing of 3.9 kb of the region surrounding the Tn501 insertion site revealed three large open reading frames, one of which would be interrupted by the Tn501 insertion in the mutant. This latter open reading frame, named opdE (for putative regulator of oprD expression), predicted a hydrophobic protein of M(r) 41,592. Using the above-mentioned oligonucleotide, the oprD structural gene was cloned and expressed in Escherichia coli on a 2.1-kb Bam HI-KpnI fragment. DNA sequencing predicted a 420 amino acid mature OprD protein with a 23 amino acid signal sequence.

Direct, simplified, and sensitive assay of angiotensin II in plasma extracts performed with a high-affinity monoclonal antibody

A very simple, fast, and sensitive RIA of angiotensin (Ang) II has been developed, based on a monoclonal antibody with high affinity and specificity, making possible the direct measurement of circulating Ang II in human plasma after solid-phase extraction. The purified monoclonal antibody 4D8 has an association constant of 1.3 x 10(11) L/mol with Ang II and a cross-reactivity of < 1% for Ang I. The assay can detect as little as 0.8 fmol of Ang II in 2 mL of plasma and is not influenced by the presence of Ang I. Analytical recoveries between 112% and 116% were obtained for Ang II added to human plasma at physiological concentrations. Comparison of the RIA with a reversed-phase, high-performance liquid chromatographic method followed by RIA to measure Ang II in human plasma samples from normal and hypertensive subjects--and from normotensive subjects before and after an acute inhibition of angiotensin-converting enzyme with captopril (50 mg)--showed a high degree of correlation (r2 = 0.93) between the two methods.

Direct, Simplified, and Sensitive Assay of Angiotensin II in Plasma Extracts Performed with a High-Affinity Monoclonal Antibody

A very simple, fast, and sensitive RIA of angiotensin (Ang) II has been developed, based on a monoclonal antibody with high affinity and specificity, making possible the direct measurement of circulating Ang II in human plasma after solid-phase extraction. The purified monoclonal antibody 4D8 has an association constant of 1.3 x 10(11) L/mol with Ang II and a cross-reactivity of &lt; 1% for Ang I. The assay can detect as little as 0.8 fmol of Ang II in 2 mL of plasma and is not influenced by the presence of Ang I. Analytical recoveries between 112% and 116% were obtained for Ang II added to human plasma at physiological concentrations. Comparison of the RIA with a reversed-phase, high-performance liquid chromatographic method followed by RIA to measure Ang II in human plasma samples from normal and hypertensive subjects--and from normotensive subjects before and after an acute inhibition of angiotensin-converting enzyme with captopril (50 mg)--showed a high degree of correlation (r2 = 0.93) between the two methods.

Re-expression of alpha skeletal actin and regulation of alpha 1 adrenoceptor signalling in DOCA-salt hypertension in rats

OBJECTIVE

To determine the effects of increased sympathetic nervous system activity in humoral hypertension on the regulation of surface alpha 1 adrenoceptors and signal transduction, deoxycorticosterone acetate (DOCA) salt hypertension was induced in rats and the animals killed three weeks following the initiation of hypertension.

METHODS

Experiments were performed on male Sprague-Dawley rats, weighing 250-300 g, divided into two groups: DOCA-salt (n = 75), and control (n = 60). Radioligand binding studies of the alpha 1 adrenoceptors, noradrenaline stimulated phosphoinositol turnover, ADP ribosylation of 41 kD substrate by pertussis toxin, and myocardial noradrenaline content were measured in the ventricular myocardium. The expression of sarcomeric actin isoforms was examined by northern blot and hybridisation with specific oligonucleotide probes.

RESULTS

The density of alpha 1 adrenoceptors was decreased by 51% in DOCA-salt treated rats. However, noradrenaline stimulated phosphoinositol turnover in myocytes from DOCA-salt hearts was not diminished. The relative quantities of pertussis toxin labelled substrates did not differ in experimental and control hearts. Myocardial noradrenaline content was reduced by 60% in DOCA-salt hearts. Northern blots on RNA extracted from hypertrophic hearts of DOCA-salt treated rats showed an upregulation of alpha skeletal actin.

CONCLUSIONS

The adrenergic state present in short term DOCA-salt hypertensive hypertrophy is characterised by enhanced signal transduction via the alpha 1 adrenoceptors and the re-expression of alpha skeletal actin in enlarging myocytes.

The effect of IH764-3 on fibroblast proliferation and function

The effect of IH764-3, a potent component isolated from Salvia miltiorrhiza, on the proliferation and function of cultured fibroblasts was studied. It was found that the fibroblast growth curve had a dose-dependent relationship with IH764-3 concentration. The incorporation of 3H-TdR and 3H-proline into fibroblasts was significantly inhibited by IH764-3, and calmodulin, fibronectin and thrombospondin contents in the test group were obviously lower than those in the control group. Flow cytometry showed that in the IH764-3-treated group, the percentage of cells in G0/G1 phase was higher than that in the control. Electron microscopic observation (TEM and SEM) showed that in the treated group, collagen secretion was decreased. All of these results indicate that IH764-3 exerts a direct inhibitory effect on fibroblast proliferation and affects their ability to synthesize collagen.

Chronic coronary arterial stenosis impairs alpha 1-adrenoreceptor signaling and cardiac performance in rats

Coronary stenosis was induced in rats to determine whether chronic coronary artery constriction resulted in impairment of cardiac pump performance, alterations in alpha 1-adrenoreceptor signal transduction, and inadequate myocardial hypertrophy, and these parameters were examined 6 mo later. A 50% reduction in coronary diameter was associated with an elevation in left ventricular end-diastolic pressure, whereas left ventricular peak systolic pressure, rate of pressure rise and decay were reduced. The hypertrophic response was modest, since statistically significant increases of 11% and 23% in left and right ventricular weights were measured. Radioligand binding documented an 18% and a 38% statistically significant reduction in alpha 1-adrenoreceptor density of the left and right myocardium, respectively. ADP ribosylation of the 41-kDa substrate by pertussis toxin showed a 16% significant decrease of this parameter in the left myocardium. Moreover, a 29% decrease in norepinephrine stimulated phosphoinositol turnover was seen in myocytes, and this change was statistically significant. The depressed generation of intracellular second messengers linked to the alpha 1-adrenoreceptors was found in conjunction with a 19% significant reduction in myocardial norepinephrine content. In conclusion, the long-term effects of coronary stenosis involve impaired transduction of adrenergic signals, which, in combination with constraints on myocardial growth, may participate in the onset of ventricular dysfunction in this model.

Identification and characterization of neutral endopeptidase in endothelial cells from venous or arterial origins

Neutral endopeptidase (NEP; enkephalinase, EC 3.4.24.11) is a cell membrane-associated zinc metalloprotease, which cleaves peptides like atrial natriuretic peptide (ANP) on the amino side of hydrophobic amino acids. Although NEP is mainly located in reabsorptive epithelia (kidney proximal tubule), it is also present in non-epithelial cells such as neuronal cells. As the renal NEP cannot account for the entire ANP metabolism, other locations were postulated. The present experiments show its expression in endothelial cells (EC) from arterial (bovine pulmonary, porcine, and human aorta) and venous (human umbilical, rabbit ear marginal) origins. Three different methods were used to demonstrate the presence of the protein and its mRNA. 1) NEP enzymatic activity was estimated using both a synthetic ([D-Ala2,Leu5]enkephalin) and a natural substrate (bradykinin). Using the synthetic substrate, the enzymatic activity in EC was completely blocked by thiorphan, a specific NEP inhibitor with an IC50 value in the nanomolar range. In contrast, captopril, bestatin, [2-guanidinoethylmercapto]succinic acid, inhibitors of angiotensin-converting enzyme, aminopeptidases, and carboxypeptidases, respectively, were 10,000 times less active, revealing an inhibition profile similar to that of the purified enzyme. Bradykinin, a natural substrate of NEP, was in part metabolized by NEP, in the presence of captopril, since 50% of the formation of the major metabolite bradykinin 1-7 was inhibited by thiorphan. 2) Immunoreactive NEP was detected on the plasma membrane of rabbit EC using a monoclonal antibody directed against the homologous renal enzyme. 3) NEP mRNA was detected by Northern blot analysis of rabbit EC as a major transcript of 3.9 kilobases. Reverse transcriptase polymerase chain reaction amplification showed the presence of a specific transcript in all EC tested. Therefore, endothelial NEP may play an important role in the inactivation of ANP, bradykinin, and endothelins by its localization facing the circulating vasoactive peptides.

Hypertension in Dahl salt-sensitive rats: biochemical and immunohistochemical studies

1. The renin-angiotensin and kinin-kallikrein systems of Dahl salt-sensitive and salt-resistant rats fed diets with different salt contents were analysed using biochemical and immunocytochemical techniques. 2. Blood pressure increased by 45% in salt-sensitive rats only, after 4 weeks on a high-salt diet. The plasma renin activity and plasma angiotensin II concentration remained at the same levels in salt-sensitive rats on the high-salt diet as on the normal salt diet, whereas the plasma renin activity and plasma angiotensin II concentration of salt-resistant rats fed the high-salt diet were lower. The plasma renin activity and the plasma angiotensin II concentration were elevated in both salt-resistant and salt-sensitive rats fed the salt-deficient diet but were much more elevated in salt-resistant than in salt-sensitive rats. 3. The kidney immunocytochemical data paralleled the data on plasma parameters. Salt-sensitive rats had fewer renin positive juxtaglomerular apparatuses than salt-resistant rats on the normal diet, and the increase on the sodium-deficient diet was also smaller in salt-sensitive rats. Salt-sensitive rats fed the high-salt diet and the standard diet had almost no angiotensin II immunoreactivity compared with the salt-resistant rats on the same diets. 4. The total renal kallikrein content of salt-sensitive rats was lower than that of salt-resistant rats on all three diets, as was the amount of kallikrein excreted in the urine on the standard and the high-salt diets. The differences resulted from a reduction in active kallikrein. The increase in kallikrein in salt-sensitive and salt-resistant rats on the salt-deficient diet was not significantly different. 5. There were similar changes in immunopositive kallikrein in the kidneys of salt-sensitive and salt-resistant rats with diet, with a large increase in kallikrein biosynthesis on the low-salt diet. The plasma concentration of high-molecular-mass kininogen was not significantly different in salt-sensitive and salt-resistant rats, but there was a significant increase in T-kininogen in salt-sensitive rats fed the high-salt diet. 6. In conclusion, the absence of decreases in the plasma renin activity and the plasma angiotensin II concentration in salt-sensitive rats fed the high-salt diet might partially explain the increase in blood pressure.

An immune model of beryllium-induced pulmonary granulomata in mice. Histopathology, immune reactivity, and flow-cytometric analysis of bronchoalveolar lavage-derived cells

BACKGROUND

Beryllium compounds can cause acute and chronic lung injury in humans. Although models of chronic granulomatous lung disease have been established in various animal species, a murine model of beryllium-induced chronic lung disease has not been established.

EXPERIMENTAL DESIGN

Beryllium was introduced intratracheally either as a soluble salt (BeSO4) or in particulate form (BeO). Various preimmunization protocols were used to enhance immune-mediated pulmonary changes. Cells obtained by bronchoalveolar lavage (BAL) were analyzed using flow cytometry, and the observations correlated with in vitro immune responses and with lung histopathology.

RESULTS

Histologic changes were consistently found in mice preimmunized with BeSO4.4H2O plus syngeneic serum. Addition of complete or incomplete Freund's adjuvant to the preimmunization protocol was not necessary to induce granulomatous changes. BAL showed a significant increase in lymphocytes at 2, 4, and 8 weeks after intratracheal BeSO4. Approximately one-third of BAL lymphocytes expressed the gamma/delta T lymphocyte receptor at 2 weeks; at 4 weeks the lymphocytes were predominantly Thy1+, L3T4+ (CD4+) and expressed only the alpha/beta T lymphocyte receptor. Only BAL lymphocytes from mice preimmunized with BeSO4/serum and challenged with BeSO4/serum showed significant in vitro proliferation in response to BeSO4. Macrophage activation antigens (Mac-2, Mac-3) were expressed only during the acute inflammatory phase (2 weeks) whereas increased expression of a monocyte/macrophage antigen (Mac-1) remained elevated beyond the inflammatory period in some instances. Attempts to induce similar lesions in BALB/c and C57BL6/J mice were unsuccessful. Genetic differences at the H-2 major histocompatibility complex gene complex may account for the differential responses to BeSO4 among various mouse strains. A single exposure to BeO also induced histopathologic changes in the lung which correlated with BAL cellularity, but these changes were only observed 8 months after exposure and did not proceed to frank granulomas.

CONCLUSIONS

A murine model of granulomatous lung disease may prove useful in understanding the genetic and immunologic factors that determine the response to beryllium. The animal model may also have implications for pulmonary sarcoidosis, a disease of unknown cause(s), whose disease manifestations and BAL profiles are difficult to distinguish clinically and pathologically from chronic beryllium disease.

Fe2+ and phosphate interactions in bacterial ferritin from Azotobacter vinelandii

Fe2+ binding to both apo- and holo- bacterial ferritin from Azotobacter vinelandii (AVBF) was measured as a function of pH under carefully controlled anaerobic conditions. Fe2+ binding to apo-AVBF is strongly pH dependent with 25 Fe2+ ions/apo-AVBF binding tightly at pH 5.5 and over 150 Fe2+/apo-AVBF at pH 9.0. Holo-AVBF gave a similar pH-dependent binding profile with over 400 Fe2+/AVBF binding at pH of 9.0. Proton release per Fe2+ bound to either AVBF protein increases with increasing pH until a total of about two protons are released at pH 9.0. These binding results are both qualitatively and quantitatively different from corresponding measurements (Jacobs et al., 1989) on apo- and holo- mammalian ferritin (MF) where less Fe2+ binds in both cases. The high level of Fe2+ binding to holo-AVBF relative to that of mammalian ferritin is a consequence of the higher phosphate content in the core of AVBF. Reduction of AVBF by either dithionite or methyl viologen in the absence of chelating agents demonstrated that phosphate, but not Fe2+, is released from the AVBF core in amounts commensurate with the degree of iron reduction, although even at 100% reduction considerable phosphate remains associated with the reduced mineral core. Fe2+ binding to holo-AVBF made deficient in phosphate was lower than that of native AVBF, while the addition of phosphate to native holo-AVBF increased the Fe2+ binding capacity. These results clearly support the role of phosphate as the site of interaction of Fe2+ with the AVBF mineral core.(ABSTRACT TRUNCATED AT 250 WORDS)

Asymptomatic impacted teeth in edentulous jaws undergoing preprosthetic surgery. A long-term evaluation

A long-term evaluation is made of 15 patients with asymptomatic impacted teeth in edentulous jaws. Seventeen impacted teeth in 15 patients were recorded and analysed. They were located in denture-bearing areas and in areas undergoing preprosthetic surgery. All patients, except one lost after 1-year period, were followed clinically and radiographically for 1 to 10 years with an average of 4 years. The asymptomatic impacted teeth in edentulous jaws embedded in bone or covered with mucosa did not cause any problem to the patients. The findings of this study support the view that removal of asymptomatic impacted teeth in denture-bearing areas, or in areas undergoing preprosthetic surgery, is unnecessary as long as the integrity of the covering tissues is preserved. A policy or radiological surveillance is recommended.

A study on optimum load for physical work

Five healthy men were chosen as experimental subjects and were divided into groups at random. The subjects walked with a load in a shoulder-waist-back manner on the treadmill at the speed of 5, 7 and 9 km h-1. The parameters measured were as follows: oxygen expenditure, energy consumption, heart rate and self appraisal. Based on the experimental results and analysis of multiple regression, the authors suggested that physical loading should not exceed 25 kg (i.e. roughly equal to 39% of average body weight of male Chinese), when the walking speed was at 5 km h-1. The suitable loading at physical work would be 20 kg (i.e. equal to 31% of the average body weight of male Chinese).

Acupuncture at otoacupoint heart for treatment of vascular hypertension

The immediate, short-term and long-term depressor effects, the immediate effects on cardiac functions in grade II and grade III vascular hypertension, and the effects on angiotensin II in grade III vascular hypertension by acupuncture at otoacupoint Heart were studied in 30 cases of vascular hypertensive patients. The immediate depressor effect of acupuncture at otoacupoint Stomach was also recorded for comparison. It was found that acupuncture at otoacupoint Heart produced marked immediate depressor effect, and the short-term effective rate was 100%, the long-term effective rate was 63.3%, as well as evident immediate effects on cardiac functional activities in grade II and grade III hypertension and marked effects on angiotensin II in grade III hypertension. Acupuncture at otoacupoint Stomach produced no depressor effect on vascular hypertension.

Experimental investigation of Bessel beam characteristics

We report on an experimental characterization of Bessel beams with finite apertures. We show that real Bessel beams can be generated with intensity profiles that closely resemble the ideal J(0)(2) transverseintensity distribution of Bessel beams. We also show interferometrically that these beams have planar phase fronts with pi-phase shifts from one Bessel ring to the next. We report tolerance conditions for Bessel beam generation and give an example of this generation that uses an unstable resonator as the light source.

The efficient intracellular sequestration of the insulin-regulatable glucose transporter (GLUT-4) is conferred by the NH2 terminus

GLUT-4 is the major facilitative glucose transporter isoform in tissues that exhibit insulin-stimulated glucose transport. Insulin regulates glucose transport by the rapid translocation of GLUT-4 from an intracellular compartment to the plasma membrane. A critical feature of this process is the efficient exclusion of GLUT-4 from the plasma membrane in the absence of insulin. To identify the amino acid domains of GLUT-4 which confer intracellular sequestration, we analyzed the subcellular distribution of chimeric glucose transporters comprised of GLUT-4 and a homologous isoform, GLUT-1, which is found predominantly at the cell surface. These chimeric transporters were transiently expressed in CHO cells using a double subgenomic recombinant Sindbis virus vector. We have found that wild-type GLUT-4 is targeted to an intracellular compartment in CHO cells which is morphologically similar to that observed in adipocytes and muscle cells. Sindbis virus-produced GLUT-1 was predominantly expressed at the cell surface. Substitution of the GLUT-4 amino-terminal region with that of GLUT-1 abolished the efficient intracellular sequestration of GLUT-4. Conversely, substitution of the NH2 terminus of GLUT-1 with that of GLUT-4 resulted in marked intracellular sequestration of GLUT-1. These data indicate that the NH2-terminus of GLUT-4 is both necessary and sufficient for intracellular sequestration.

A comparative study of the efficacy and morbidity of five techniques for ridge augmentation of the mandible

Severely atrophic mandibles were augmented in 254 patients using five different surgical procedures, followed by total lowering of the floor of the mouth, vestibuloplasty, and skin graft. Patients were evaluated on a long-term basis to compare efficacy of treatment subjectively by recording patient complaints and by objectively assessing ridge form clinically and radiographically. Patients, in general, were pleased with the short- and long-term results of all five procedures. The ideal ridge form, comma-shaped, was obtained at a much higher rate with the three procedures using hydroxylapatite (HA) alone or in combination with collagen (HA-PFC). Ridge height loss both anteriorly and posteriorly was more severe in the two visor groups with bone graft or with HA than in those with only the alloplast. Labial sensory alterations more frequently occurred in the visor bone graft group, and wound dehiscence and lack of skin graft take were seen most often in the HA-PFC groups. Despite great differences in the quality of ridges obtained and in the number of complications between the visor groups and the alloplast groups, general patient satisfaction with any of the five procedures could be explained by the severity of the original complaints and because muscle interference has been eliminated in all cases by lowering of the floor of the mouth.

Stabilities and properties of multilinked hemoglobins

Crosslinking of both human and dog hemoglobin has been done with a variety of reagents to produce singly, doubly and multiply crosslinked hemoglobins. Succinate and glutarate diaspirins did not crosslink deoxy human hemoglobin in good yield, in contrast to the fumarate analog (DBSF). Deoxy dog Hb did not react well with DBSF, but oxy dog Hb did react, giving crosslinked tetramers as well as dimers on SDS electrophoresis. Crosslinking with a short, rigid reagent (difluorodinitrobenzene) resulted in a similar product for both oxy and deoxy hemoglobin that had high stability and oxygen affinity. The trilinker, tris-chloroethylamine, produced a more stable product than the corresponding crosslinker, bis-chloroethylamine. Double crosslinking oxy Hb with DBSF and dimethylpimelimidate or with DBSF followed by deoxygenation and recrosslinking with DBSF gave products with higher denaturation temperatures. The diaspirin double crosslinked product had high oxygen affinity.

Synthesis and biodistribution of the alpha 2-adrenergic receptor antagonist (11C)WY26703. Use as a radioligand for positron emission tomography

The purpose of these experiments was to label an alpha 2-adrenergic receptor ligand with a positron emitting isotope and then test this radioligand in vivo. No-carrier-added [11C]WY26703 was synthesized by methylation of its desmethyl precursor, WY27050 with [11C]H3I followed by purification with HPLC in 14% yield in a synthesis time of 35 min from EOB. Ki values for unlabeled WY26703, ranged from 0.52-1.55 nM in tissues that express a single alpha 2-adrenergic receptor subtype. Tail vein injections of [11C]WY26703 in mice revealed that the compound was distributed in the brain, heart, lungs, spleen, and kidneys. In the brains of rats treated with atipamezole, an alpha 2-adrenergic receptor antagonist, there was no decrease in [11C] accumulation indicating a lack of observable specific binding of the radioligand. When brain tissue was homogenized and filtered, however, atipamezole decreased [11C] activity by 53%. Therefore, [11C]WY26703 crosses the blood-brain barrier and specifically binds to alpha 2-adrenergic receptors with high affinity. Atipamezole treatment decreased only the area of the locus coeruleus [11C] value of the various regions of the brain. The affinity, however, of [11C]WY26703 does not appear to distinguish alpha 2-receptors from nonspecific binding sites. PET study of [11C]WY26703 in a Rhesus monkey showed that influx of [11C]WY26703 into the brain was high for the first few minutes but radioactivity then declined rapidly and did not retain in a specific brain region. This suggests that [11C]WY26703 may not be a useful ligand for imaging human alpha 2-adrenergic receptors by positron emission tomography.

The transition from late G1 to early S phase is most vulnerable to the coclastogenic effect of ultraviolet radiation plus arsenite

It has previously been reported that chromosome aberrations induced by ultraviolet (UV) radiation can be enhanced by treatment with sodium arsenite for 24 h post-irradiation. Using synchronized CHO-K1 cells, it has now been established that cells in the transitional stage from late G1 to early S phase are most vulnerable to the coclastogenic effect of treatment with UV radiation and arsenite. This result cannot be explained by the special vulnerability of cells in the late G1 to early S transition to UV clastogenicity, as the coclastogenic effects of UV and caffeine or UV and arabinofuranosylcytosine were detected when treating the mid-S but not late-G1 or G2 phase cells.