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Biomedical subjects

H Kurokawa

Publications and source records attributed to H Kurokawa.

At least 19 recordsLinked to original sources

Traumatic neuroma in the lower lip arising following laser/cryosurgery to treat a mucocele.

A 15-year-old girl presented with a painless recurrent swelling on her right lower lip mucosa for about 10 months. She had a past history of treatment with laser surgery and cryosurgery. The clinical diagnosis was a 'recurrent mucocele'. Histopathological examination of the surgical specimen revealed a mucocele close to a neuroma with irregular nerve fascicles, leading to a diagnosis 'mucocele accompanied with a traumatic neuroma'. In the present report, the traumatic neuroma appears to have arisen following laser or cryosurgery.

Adolescent↗

Transfusion transmitted virus (TTV) in dental patients.

Transfusion transmitted virus (TTV) is a new DNA virus found in patients with post-transfusion hepatitis. The prevalence of this virus among dental patients has not been reported, therefore, the prevalence of TTV infection in consecutive dental inpatients was evaluated. TTV DNA was assayed by the polymerase chain reaction (PCR) in 441 dental inpatients with oral cancer (n=192) or oral cysts (n=249). The serum HBs antigen and HCV antibody as well as aspartate transaminase (AST), alanine transaminase (ALT), and gamma glutamyl transpeptidase (gamma-GTP) concentrations were also measured. Of 441 subjects, 137 were infected with TTV (31.1%). This prevalence of TTV was much higher than that of HBV or HCV (HBV 1.2%; HCV 6.0%) in these dental patients. There was no gender or age difference in the prevalence of TTV infection. Of the 192 patients with oral cancer, 57 subjects had TTV in their sera, while 80 of 249 with oral cystic disease had TTV. The prevalence of TTV was similar between the two different disease groups. Neither the serum ALT nor serum AST concentrations were different between the subjects positive and negative for TTV DNA. In hospitalized dental patients, 31.1% were infected with TTV. The prevalence of TTV was much higher than that of HBV or HCV. There was no difference in the prevalence of TTV between subjects with cancer and cysts. Dentists should maintain high standards of infection control when treating any dental patient.

Adolescent↗

Target-induced conformational adaptation of calmodulin revealed by the crystal structure of a complex with nematode Ca(2+)/calmodulin-dependent kinase kinase peptide.

Calmodulin (CaM) is a ubiquitous calcium (Ca(2+)) sensor which binds and regulates protein serine/threonine kinases along with many other proteins in a Ca(2+)-dependent manner. For this multi-functionality, conformational plasticity is essential; however, the nature and magnitude of CaM's plasticity still remains largely undetermined. Here, we present the 1.8 A resolution crystal structure of Ca(2+)/CaM, complexed with the 27-residue synthetic peptide corresponding to the CaM-binding domain of the nematode Caenorhabditis elegans Ca(2+)/CaM-dependent kinase kinase (CaMKK). The peptide bound in this crystal structure is a homologue of the previously NMR-derived complex with rat CaMKK, but benefits from improved structural resolution. Careful comparison of the present structure to previous crystal structures of CaM complexed with unrelated peptides derived from myosin light chain kinase and CaM kinase II, allow a quantitative analysis of the differences in the relative orientation of the N and C-terminal domains of CaM, defined as a screw axis rotation angle ranging from 156 degrees to 196 degrees. The principal differences in CaM interaction with various peptides are associated with the N-terminal domain of CaM. Unlike the C-terminal domain, which remains unchanged internally, the N-terminal domain of CaM displays significant differences in the EF-hand helix orientation between this and other CaM structures. Three hydrogen bonds between CaM and the peptide (E87-R336, E87-T339 and K75-T339) along with two salt bridges (E11-R349 and E114-K334) are the most probable determinants for the binding direction of the CaMKK peptide to CaM.

Amino Acid Sequence↗

Risk stratification using serum concentrations of cardiac troponin T in patients with end-stage renal disease on chronic maintenance dialysis.

BACKGROUND: It has been recently suggested that cardiac troponin T (cTnT) may be more sensitive than troponin I (cTnI) for subclinical myocardial cell injury in patients on chronic dialysis. METHODS: We prospectively compared the predictive value of cTnT with cTnI, atrial (ANP) and brain natriuretic peptide (BNP) in 100 consecutive outpatients on chronic dialysis without acute coronary syndromes over a period of 3 months, and assessed whether the combination of cTnT with clinical information including age, duration of dialysis, and medical histories was useful for risk stratification of these patients. During the 2-year follow-up period, 19 patients died, mostly due to cardiac causes (53%). RESULTS: The area under the receiver operator characteristic (ROC) curve for the cTnT as predictor of both overall and cardiac death was significantly greater than the area under the cTnI curve (p < 0.0001 and p = 0.01), the BNP curve (p < 0.001 and p < 0.01) or the ANP curve (p < 0.0001 and p < 0.005). In a stepwise multivariate Cox regression analysis, only cTnT (p < 0.05 and p < 0.01) and a history of heart failure requiring hospitalization (p < 0.05 and p < 0.005) were independent predictors of both all cause and cardiac mortality. Using parameters of cTnT > or =0.1 microg/l and/or history of heart failure, the overall and cardiac mortality rate for the low risk group (n=66) were 4.5% and 1.5%, respectively, 40% and 16% for the intermediate risk group (n=25), and 67% and 56% for the high risk group (n=9). CONCLUSION: cTnT concentrations offer a higher prognostic accuracy than cTnI, ANP and BNP in patients on chronic dialysis. The combination of elevated cTnT and a history of heart failure may be a highly effective means of risk stratification of these patients.

Adult↗

Mechanism of the radiosensitization induced by vinorelbine in human non-small cell lung cancer cells.

Vinorelbine (Navelbine, KW-2307), a semisynthetic vinca alkaloid, is a potent inhibitor of mitotic microtubule polymerization. The aims of this study were to demonstrate radiosensitization produced by vinorelbine in human non-small cell lung cancer (NSCLC) PC-9 cells and to elucidate the cellular mechanism of radiosensitization. A clonogenic assay demonstrated that PC-9 cells were sensitized to radiation by vinorelbine with a maximal sensitizer enhancement ratio at a 10% cell survival level of 1.35 after 24-h exposure to vinorelbine at 20 nM. After 24-h exposure to vinorelbine at 20 nM, the approximately 67% of the cells that had accumulated in the G2/M-phase were cultured in the absence of vinorelbine and then irradiated at a dose of 8 Gy. Flow cytometric analyses showed prolonged G2/M accumulation concomitant with continuous polyploidization, and induction of apoptosis was observed in the cells subjected to the combination of vinorelbine-pretreatment and radiation. Polyploidization and induction of apoptosis were confirmed by morphological examination and a DNA fragmentation assay, respectively. We concluded that vinorelbine at a minimally toxic concentration moderately sensitizes human NSCLC cells to radiation by causing accumulation of cells in the G2/M-phase of the cell cycle. Prolonged G2/M accumulation concomitant with continuous polyploidization and increased susceptibility to induction of apoptosis may be associated with the cellular mechanism of radiosensitization produced by vinorelbine.

Carcinoma, Non-Small-Cell Lung↗

Synthesis of variously oxidized abietane diterpenes and their antibacterial activities against MRSA and VRE.

Variously oxidized 12 natural abietanes, 6,7-dehydroferruginol methyl ether (3), ferruginol (5), 11-hydroxy-12-oxo-7,9(11),13-abietatriene (7), royleanone (9), demethyl cryptojaponol (12), salvinolone (14), sugiol methyl ether (16), sugiol (17), 5,6-dehydrosugiol methyl ether (19), 5,6-dehydrosugiol (20), 6beta-hydroxyferruginol (23), and taxodione (25) were synthesized. Antimicrobial activities of synthesized phenolic diterpenes and their related compounds against MRSA and VRE were evaluated. Phenols (12-hydroxyabieta-8,11,13-trien-6-one 22 and 23), catechols (12 and 14) and taxodione 25 showed potent activity with 4-10 microg/mL of MIC against MRSA and 4-16 microg/mL of MIC against VRE. (-)-Ferruginol showed more potent activity than natural type (+)-ferruginol. Quinone methide 7 showed the most potent activity with 0.5-1 microg/mL of MIC against both MRSA and VRE.

Anti-Bacterial Agents↗

Solid-state microstructures, thermal properties, and crystallization of biodegradable poly(butylene succinate) (PBS) and its copolyesters.

Studies of solid-state structures under different crystallization conditions, melting behavior, and crystal growth kinetics are reported for biodegradable aliphatic poly(butylene succinate) (PBS) and its random copolyesters of poly(butylene succinate-co-14 mol %ethylene succinate) [P(BS-co-14 mol %ES)] and poly(butylene succinate-co-15 mol %hexamethylene succinate) [P(BS-co-15 mol %HS)]. The crystal structures of two copolyesters determined by wide-angle X-ray diffraction (WAXD) are the same as that of the PBS homopolymer, suggesting that the second comonomers ES or HS units are excluded from the crystalline core and are in an amorphous state. The further investigations on the crystalline and amorphous phase structures and sizes by small-angle X-ray scattering (SAXS) method have provided quantitative evidence that the existence of second comonomers increases the amorphous thickness of copolyesters but that the influences of comonomers on the lamellar crystal structure and size of copolyesters are complicated. The origin of the complexity and its influences on the equilibrium melting temperature T(m)(0) of copolyester are discussed in the present paper. Gibbs-Thomson and Hoffman-Weeks equations were applied for the determination of T(m)(0) of PBS, P(BS-co-14 mol %ES), and P(BS-co-15 mol %HS)-three samples. Two equations gave different T(m)(0) values for each sample. On the basis of the Gibbs-Thomson equation, the P(BS-co-15 mol %HS) copolyester has the same T(m)(0) value as that of the PBS homopolymer, while the P(BS-co-14 mol %ES) copolyester has a lower one. This is due to the different influences of the second comonomers on the crystalline phase structure indicated by SAXS results, and the Gibbs-Thomson equation has been suggested to be more reliable. The crystal growth kinetics of the three samples was analyzed by using the secondary nucleation theory, and the influences of various parameters on the regime transition and nucleation constant were studied. Meanwhile some interrelations between regime transition temperature and melting behavior were found for the three samples.

Biodegradation, Environmental↗

Lack of association between QT dispersion and blood pressure response during dental surgery.

1. It is well known that dental surgery induces increases in blood pressure. However, the factors influencing this increase are not yet fully understood. We have determined the relationship between QTc (= QT/RR(1/2), with RR being the R-R interval in seconds) dispersion, measured with a 12-lead surface electrocardiogram, and changes in blood pressure during tooth extraction. 2. Both QTc dispersion and the power spectrum of R-R variability were determined before the dental surgery was undertaken. The low-frequency (LF; 0.041-0.140 Hz), high- frequency (HF; 0.140-0.500 Hz) and total spectral powers (TF; 0.000-4.000 Hz) were calculated and the ratio of LF to HF and the percentage of HF relative to TF (%HF; HF/TF x 100) were used as indices of sympathovagal balance and parasympathetic activities, respectively. 3. In the present study, QTc dispersion failed to correlate with LF/HF and %HF. Systolic blood pressure and pulse rate increased significantly during tooth extraction; however, changes in these variables failed to correlate with QTc dispersion. 4. These results suggest that QTc dispersion is not associated with the power spectrum of R-R variability and that it does not affect the blood pressure response during tooth extraction.

Adult↗

Direct screening of the IMP-1 metallo-beta-lactamase gene (blaIMP) from urine samples by polymerase chain reaction.

BACKGROUND: As Gram-negative bacterial isolates producing plasmid-mediated IMP-1 metallo-beta-lactamase usually demonstrate resistance to various broad-spectrum beta-lactams, including cephamycins and carbapenems, transmission and proliferation of these microorganisms in clinical settings could become a clinical threat in the near future. According to previous studies by the same authors, IMP-1-producing strains are usually isolated from urine samples. Therefore, in this study, a polymerase chain reaction (PCR) was applied for direct screening of the IMP-1 metallo-beta-lactamase gene in urine samples. METHOD: Urine samples were collected from 273 inpatients to whom various broad-spectrum beta-lactams, including carbapenems, had been administered in 57 hospitals in 1997. DNA templates for PCR analyses were prepared directly from 19 urine samples from which Serratia marcescens strains demonstrating high-level resistance (minimal inhibitory concentration > 128 microg/mL) to both ceftazidime and cefoperazone-sulbactam were later isolated. RESULTS: The IMP-1 metallo-beta-lactamase gene (blaIMP)-specific 578 bp fragments were able to be amplified successfully in eight of the 19 samples. In the seven strains isolated from the eight samples, the presence of blaIMP was also detected by a DNA hybridization analysis. The lower limit of the PCR method was determined as 1 x 10(2) CFU of blaIMP-bearing bacterial cells per 1 mL of urine sample. No false positive result was found. CONCLUSION: The PCR-aided direct screening of blaIMP is applicable to early recognition of IMP-1-producing bacteria in urine samples. This method would help to prevent nosocomial and interhospital transmission of this kind of hazardous bacteria, as well as the advancement of rigorous infection control.

Bacterial Proteins↗

Relationship between thrombolytic therapy and perfusion defect detected by Gd-DTPA-enhanced fast magnetic resonance imaging in acute myocardial infarction.

To study whether thrombolytic therapy affects Gd-DTPA-enhanced pattern and whether its pattern indicates myocardial viability, Gd-DTPA-enhanced magnetic resonance imaging (MRI) was performed in 43 patients with reperfused acute myocardial infarction 14.8+/-5.0 days after onset with breathhold scanning on a 1.5-T whole body system. The hypoenhanced area at 90 sec after contrast injection was defined as a perfusion defect (PD). Patients were divided into PD(+) and PD(-) groups. The PD was detected in 77.8% of patients treated with direct percutaneous transluminal coronary angioplasty (PTCA) and in 28.6% of patients treated by thrombolytic therapy with or without PTCA in the thrombolysis in myocardial infarction grade 3 group (p < 0.05). The myocardial wall was divided into seven segments based on the American Heart Association committee report. Wall motion of each segment was classified by one of six patterns (wall motion score [WMS]: dyskinesis, -1; akinesis, 0; severe hypokinesis, 1; hypokinesis, 2; slight hypokinesis, 3; normal, 4). By echocardiography, the average WMS and ejection fraction were similar between the PD(+) group and the PD(-) group on admission. Those parameters were significantly worse in the PD(+) group than in PD(-) group 1 month after onset. The change in WMS was significantly lower in the PD(+) group than in the PD(-) group. The number of patients and segments with more than two grades of improvement of WMS in the PD(+) group was significantly lower than that in the PD(-) group. Angiographically, left ventricular ejection fraction and WMS of the PD(+) group were significantly lower than those of the PD(-) group 3 months later. PDs were detected significantly less frequently in patients treated with thrombolytic therapy, suggesting that microvascular embolization related to formation of the no-reflow phenomenon.

Aged↗

Cardiovascular and sympathetic responses to dental surgery with local anesthesia.

We investigated changes in blood pressure and blood variables, including plasma catecholamines, serum glucose and insulin concentrations, during dental surgery. The study included 11 normotensive patients (age, 22.5+/-0.7 years) who underwent tooth extraction at Kyushu Dental College Hospital. Three to 7 days prior to dental surgery, blood pressure, pulse rate, and heart rate variability were measured every 30 min over 24 h. The low frequency (LF: 0.05 to 0.15 Hz) and high frequency (HF: 0.15 to 0.40 Hz) powers were calculated, and the ratio of LF to HF (LF/HF) and HF were used as indexes of sympathetic and parasympathetic activities, respectively. Lidocaine, 2% with epinephrine (1:80,000), was used as the local anesthetic for all patients. Systolic blood pressures significantly increased during dental surgery (+10.8+/-3.5 mmHg); however, this increase failed to correlate not only with baseline systolic blood pressure but with 24-h averaged blood pressures, LF/HF or HF. On the other hand, plasma epinephrine and norepinephrine concentrations increased during dental surgery, and peak values of these variables were obtained after local anesthesia and during tooth extraction, respectively. Serum glucose level increased after local anesthesia (control vs. local anesthesia: 5.16+/-0.11 vs. 5.62+/-0.10 mmol/l; p<0.01); however, plasma insulin concentrations did not change significantly. These results suggest that 1) ambulatory measurements of blood pressure and heart rate variability over 24 h cannot predict the responses of blood pressure during dental surgery, and that 2) administration of local anesthetic and tooth extraction activate sympathoadrenal outflow, resulting in an increase in serum glucose level in normotensive subjects.

Adult↗

Experimental study of fast and ultrafast T2-weighted imaging sequences using AMI-25 superparamagnetic iron oxide (SPIO).

The objective of this study was to evaluate fast and ultrafast T2-weighted images (T2WI), including echo planar imaging (EPI), using an AMI-25 agar phantom. Image quality for conventional spin echo (CSE) and turbo spin echo (TSE) was almost equivalent. In high-resolution TSE, image quality was highest due to the use of a 512 x 256 matrix. Half-Fourier single-shot turbo SE (HASTE) was associated with blurring of images, and turbo-gradient SE (TGSE) showed a deterioration of image quality. EPI also suffered from poor image quality because this method is very sensitive to magnetic field inhomogeneity. CSE showed good signal-to-noise ratio (S/N) and contrast ratio (CR), but also required the longest imaging times. Among the TSE sequences, TSE with a short echo train length (ETL) was superior in terms of S/N. The CR of EPI and fast low angle shot (FLASH) images were improved in proportion to the effective echo time (TE). At present, TSE is inferior to CSE in terms of S/N and CR. However, taking into consideration scanning time, TSE with a short ETL is thought to be suitable for routine examinations. Effective TE is an important factor in gradient echo (GRE) examinations.

Contrast Media↗

Inhibition of erbB receptor (HER) tyrosine kinases as a strategy to abrogate antiestrogen resistance in human breast cancer.

It has been proposed that binding of ligand to the estrogen receptor (ER) releases its association with transcriptional corepressors, allowing the ER to recruit coactivators, which possess histone acetylase activity, and induce transcription of gene promoters containing estrogen response elements. It has also been proposed that the antiestrogen tamoxifen recruits transcriptional corepressors to the AF-2 region of the hormone-binding domain of the ER, thus blocking ER-mediated transcription. The ER cross-talks with a number of mitogenic signaling pathways and second messengers, like the epidermal growth factor receptor, the insulin-like growth factor-I receptor, mitogen-activated protein (MAP) kinase, phosphatidylinositol-3 kinase/Akt, dopamine, and cyclic AMP. Some of these molecules may: (a) support ligand-independent ER transcription; (b) increase the association of ER with coactivators of transcription; and/or (c) reduce the antiestrogen-induced association of ER with corepressors. These events either alone or in combination may result in hormone independence and/or antiestrogen resistance. We have examined whether signaling by HER2/neu (erbB-2) receptor tyrosine kinase, which can induce antiestrogen resistance, can also disrupt the tamoxifen-induced interaction of ER with transcriptional corepressors. Notably, tamoxifen-induced association of ER with the transcriptional corepressors N-CoR or SMRT was reduced in HER2-overexpressing breast tumor cells but not in cells with low HER2 levels. Small molecule inhibitors of the HER2 kinase or MAP extracellular signal-regulated kinase 1/2 or dominant-negative MAP extracellular signal-regulated kinase 1/2 constructs restored the inhibitory effect of tamoxifen on both ER-mediated transcription and tumor cell proliferation. Treatment with both tamoxifen and the small molecule HER1/2 kinase inhibitor AG1478 reduced mitogen-activated protein kinase activity and markedly reduced growth of established MCF-7/HER2 xenografts in athymic nude mice. Similar results have been obtained with ZD1839 ("Iressa"), an epidermal growth factor receptor (HER1) tyrosine kinase inhibitor. Taken together, these data suggest that exogenous inhibitors of the HER-signaling network and other mitogenic pathways can abrogate or delay the emergence of antiestrogen resistance, thus providing an evaluable therapeutic strategy in human breast carcinoma.

Breast Neoplasms↗

Inhibition of HER2/neu (erbB-2) and mitogen-activated protein kinases enhances tamoxifen action against HER2-overexpressing, tamoxifen-resistant breast cancer cells.

HER2/neu (erbB-2) overexpression has been causally associated with tamoxifen resistance in human breast cancer cells. Forced expression of HER2 in MCF-7 breast cancer cells resulted in mitogen-activated protein kinase (MAPK) hyperactivity and tamoxifen resistance. Inhibition of HER2 and MAPKs with AG1478 and U0126, respectively, as well as dominant-negative MEK-1/2 constructs restored the inhibitory effect of tamoxifen on estrogen receptor (ER)-mediated transcription and cell proliferation. Both AG1478 and U0126 also restored the tamoxifen-mediated association of ER with nuclear receptor corepressor (N-CoR) in the antiestrogen-resistant MCF-7 cells. Treatment with a combination of tamoxifen and a HER2 kinase inhibitor reduced tumor MAPK activity and markedly prevented growth of HER2-overexpressing MCF-7 xenografts in athymic mice. Thus, blockade of HER2 and MAPK signaling may enhance tamoxifen action and abrogate antiestrogen resistance in human breast cancer.

Animals↗

Ectopic p16(ink4) expression enhances CPT-11-induced apoptosis through increased delay in S-phase progression in human non-small-cell-lung-cancer cells.

A tumor-suppressor gene, p16(INK4), which is deleted or mutated in tumors, regulates cell-cycle progression through a G(1)-S restriction point by inhibiting CDK4(CDK6)/cyclin-D-mediated phosphorylation of pRb. We have found that ectopic p16(INK4) expression increased cellular sensitivity of human non-small-cell-lung-cancer (NSCLC) A549 cells to a selective growth-inhibitory effect induced by the topoisomerase-I inhibitor 11, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy camptothecin (CPT-11) in vitro. In this study, we observed enhanced apoptosis characterized by DNA fragmentation in A549 cells transfected with p16(INK4) cDNA (A549/p16-1) and treated with CPT-11. This apoptosis was suppressed by the inhibitor of interleukin-1beta-converting enzyme (ICE/caspase-1) or ICE-like proteases, Z-Asp-CH2-DCB, as determined by DNA fragmentation and proteolytic cleavage of poly(ADP-ribose) polymerase, a natural substrate for CPP32/caspase-3. In A549/p16-1 cells, cytosolic peptidase activities that cleaved Z-DEVD-7-amino-4-trifluoromethylcoumarin increased during CPT-11-induced apoptosis and were suppressed by a highly specific caspase-3 and caspase-3-like inhibitor, Z-DEVD-fluoromethylketone. These findings indicate that p16(INK) is positively involved in the activation pathway of the caspase-3 induced by CPT-11. The increased delay in S-phase progression and subsequent induction of apoptosis were observed in CPT-11-treated A549/p16-1 cells on the basis of DNA histograms. Specific down-regulation of the cyclin-A protein level in A549/p16-1 cells was observed after CPT-11-treatment, whereas cyclin B, cdk2, and cdc2 protein levels were unaffected. These results suggest that ectopic p16(INK4) expression inappropriately decreases cyclin A and thereby terminates CPT-11-induced G(2)/M accumulation, which is followed by increased apoptosis in p16(INK4)-expressing A549 cells.

Antineoplastic Agents, Phytogenic↗

A preliminary survey of extended-spectrum beta-lactamases (ESBLs) in clinical isolates of Klebsiella pneumoniae and Escherichia coli in Japan.

We conducted a survey of extended-spectrum beta-lactamases (ESBLs) among 16805 Escherichia coli and 9794 Klebsiella pneumoniae clinical isolates recovered from 196 separate medical institutions during the period January 1997 to January 1998. Using the criteria for minimal inhibitory concentrations (MICs) of oxyimino-cephalosporins of >/=8 microg ml(-1) and confirmation by double-disk test, we detected 15 E. coli and 34 K. pneumoniae isolates producing ESBLs. Genotypes of ESBLs determined by PCR with type-specific primers included one TEM-derived and 24 SHV-derived ESBLs, in addition to 24 Toho-1-type ESBLs, one of the major types of ESBLs reported in Japan. Nucleotide sequence analysis of SHV-specific PCR products revealed that SHV-12 was the dominant type of SHV-derived ESBL. In addition, we also identified TEM-26 and SHV-2. This is the first report characterizing TEM- and SHV-derived ESBLs in Japan.

Anti-Bacterial Agents↗

Plasma concentration of brain natriuretic peptide as a biochemical marker for the evaluation of right ventricular overload and mortality in chronic respiratory disease.

The purpose of this study was to evaluate whether the plasma brain natriuretic peptide (BNP) concentration is a useful marker of right ventricular (RV) overload and whether it has prognostic value as a predictor of death in patients with chronic respiratory disease (CRD). We measured the plasma BNP and atrial natriuretic peptide (ANP) concentrations in 31 consecutive patients with CRD who underwent right-heart catheterization to evaluate pulmonary hypertension. All patients were followed for >12 months. The plasma BNP concentration closely correlated with the mean pulmonary artery pressure and pulmonary vascular resistance (r=0.62, P<0.0005 and r=0. 85, P<0.0001), and showed a weak linear correlation with cardiac output (r=-0.36, P<0.05). During the follow-up period, 5 (16%) end-stage CRD deaths (4 RV heart failure and 1 respiratory infection) and 2 non-end-stage CRD deaths occurred. In a stepwise multivariate Cox proportional-hazards regression analysis including age, sex, BNP, ANP, hemodynamic variables and the ratio of PaO(2) to fraction of inspired oxygen, only BNP (P<0.05) was an independent predictor of end-stage CRD death. The upward and leftward shift in the receiver operating characteristic curve between patients with end-stage CRD death and those without was greater for BNP than for ANP. Our findings suggest that the plasma BNP concentration may be an inexpensive, simple and useful marker of RV overload and end-stage CRD death in CRD patients. These preliminary results need to be confirmed in a large series of CRD patients.

Aged↗

A monomeric histidine kinase derived from EnvZ, an Escherichia coli osmosensor.

Histidine kinases function as dimers. The kinase domain of the osmosensing histidine kinase EnvZ of Escherichia coli consists of two domains: domain A (67 residues) responsible for histidine phosphotransfer and dimerization, and domain B (161 residues) responsible for the catalytic and ATP-binding function. The individual structures of these two domains have been recently solved by NMR spectroscopy. Here, we demonstrate that an enzymatically functional monomeric histidine kinase can be constructed by fusing in tandem two domains A and one domain B to produce a single polypeptide (A-A-B). We show that this protein, EnvZc[AAB], is soluble and exists as a stable monomer. The autophosphorylation and OmpR kinase activities of the monomeric EnvZc[AAB] are similar to that of the wild-type EnvZ, while OmpR-binding and phosphatase functions are reduced. V8 protease digestion and mutational analyses indicate that His-243 of only the amino proximal domain A is phosphorylated. Based on these results, molecular models are proposed for the structures of EnvZc[AAB] and the kinase domain of EnvZ. The present results demonstrate for the first time the construction of a functional, monomeric histidine kinase, further structural studies of which may provide important insights into the structure-function relationships of histidine kinases.

Bacterial Outer Membrane Proteins↗