[Establishment of an early risk prediction model for bloodstream infection and analysis of its predictive value in patients with extremely severe burns].

Objective: To establish an early prediction model for bloodstream infection in patients with extremely severe burns based on the screened independent risk factors of the infection, and to analyze its predictive value. Methods: A retrospective case-control study was conducted. From January 1, 2010 to December 31, 2019, 307 patients with extremely severe burns were admitted to the Department of Burns and Plastic Surgery of Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medcine, including 251 males and 56 females, aged from 33 to 55 years. According to the occurrence of bloodstream infection, the patients were divided into non-bloodstream infection group (221 cases) and bloodstream infection group (86 cases). The gender, age, body mass index, outcome, length of hospital stay of patients were compared between the two groups, and the detection of bacteria in blood microbial culture of patients was analyzed in bloodstream infection group. The included 307 patients were divided into modeling group (219 cases) and validation group (88 cases) according to the random number table with a ratio of about 7∶3. The gender, age, body mass index, total burn area, full-thickness burn area, combination of inhalation injury, implementation of mechanical ventilation, days of mechanical ventilation, days of intensive care unit (ICU) stay, outcome, length of hospital stay, complication of bloodstream infection of patients were compared between the two groups. According to the occurrence of bloodstream infection, the patients in modeling group were divided into bloodstream infection subgroup (154 cases) and non-bloodstream infection subgroup (165 cases). The total burn area, full-thickness burn area, combination of inhalation injury, implementation of mechanical ventilation, days of mechanical ventilation, and days of ICU stay of patients were compared between the two subgroups. The above-mentioned data between two groups were statistically analyzed with one-way analysis of independent sample t test, chi-square test, and Mann-Whitney U test to screen out the factors with statistically significant differences in the subgroup univariate analysis of modeling group. The factors were used as variables, and binary multivariate logistic regression analysis was performed to screen out the independent risk factors of bloodstream infection in patients with extremely severe burns, based on which the prediction model for bloodstream infection in patients with extremely severe burns of modeling group was established. The receiver operating characteristic (ROC) curve of the prediction model predicting the risk of bloodstream infection of patients in modeling group was drawn, and the area under the ROC curve was calculated. The sensitivity, specificity, and the best prediction probability were calculated according to the Youden index. According to the occurrence of bloodstream infection, the patients in validation group were divided into bloodstream infection subgroup (21 cases) and non-bloodstream infection subgroup (67 cases). The prediction probability >the best prediction probability of model was used as the judgment standard of bloodstream infection. The prediction model was used to predict the occurrence of bloodstream infection of patients in the two subgroups of validation group, and the incidence, specificity, and sensitivity for predicting bloodstream infection were calculated. In addition, the ROC curve of the prediction model predicting the risk of bloodstream infection of patients in validation group was drawn, and the area under the ROC curve was calculated. Results: Compared with those of non-bloodstream infection group, the mortality of patients in bloodstream infection group was significantly higher (χ2=8.485, P<0.01), the length of hospital stay was significantly increased (Z=-3.003, P<0.01), but there was no significant change in gender, age, or body mass index (P>0.05). In patients of bloodstream infection group, 110 strains of bacteria were detected in blood microbial culture, among which Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii were the top three bacteria, accounting for 35.45% (39/110), 26.36% (29/110), and 13.64% (15/110), respectively. Gender, age, body mass index, total burn area, full-thickness burn area, proportion of combination of inhalation injury, proportion of implementation of mechanical ventilation, days of mechanical ventilation, days of ICU stay, outcome, length of hospital stay, and proportion of complication of bloodstream infection of patients were similar between modeling group and validation group (P>0.05). Compared with those of non-bloodstream infection subgroup in modeling group, the total burn area, full-thickness burn area, proportion of combination of inhalation injury, proportion of implementation of mechanical ventilation, days of mechanical ventilation, and days of ICU stay of patients in bloodstream infection subgroup were significantly increased (Z=-4.429, t=-4.045, χ2=7.845, 8.845, Z=-3.904, -4.134, P<0.01). Binary multivariate logistic regression analysis showed that total burn area, days of ICU stay, and combination of inhalation injury were the independent risk factors for bloodstream infection of patients in modeling group (odds ratio=1.031, 1.018, 2.871, 95% confidence interval=1.004-1.059, 1.006-1.030, 1.345-6.128, P<0.05 or P<0.01). In modeling group, the area under the ROC curve was 0.773 (95% confidence interval=0.708-0.838); the sensitivity was 64.6%, the specificity was 77.9%, and the best prediction probability was 0.335 when the Youden index was 0.425. The bloodstream infection incidence of patients predicted by the prediction model in validation group was 27.27% (24/88), with specificity of 82.09% (55/67) and sensitivity of 57.14% (12/21). The area under the ROC curve in validation group was 0.759 (95% confidence interval=0.637-0.882). Conclusions: The total burn area, days of ICU stay, and combination of inhalation injury are the risk factors of bloodstream infection in patients with extremely severe burns. The early prediction model for bloodstream infection risk in patients with extremely severe burns based on these factors has certain predictive value for burn centers with relatively stable treatment methods and bacterial epidemiology.

How similar is "similar," or what is the best measure of soil spectral and physiochemical similarity?

Spectral similarity indices were used to select similar soil samples from a spectral library and improve the predictive accuracy of target samples. There are many similarity indices available, and precisely how to select the optimum index has become a critical question. Five similarity indices were evaluated: Spectral angle mapper (SAM), Euclidean distance (ED), Mahalanobis distance (MD), SAM_pca and ED_pca in the space of principal components applied to a global soil spectral library. The accordance between spectral and compositional similarity was used to select the optimum index. Then the optimum index was evaluated if it can maintain the greatest predictive accuracy when selecting similar samples from a spectral library for the prediction of a target sample using a partial least squares regression (PLSR) model. The evaluated physiochemical properties were: soil organic carbon, pH, cation exchange capacity (CEC), clay, silt, and sand content. SAM and SAM_pca selected samples were closer in composition compared to the target samples. Based on similar samples selected using these two indices, PLSR models achieved the highest predictive accuracy for all soil properties, save for CEC. This validates the hypothesis that the accordance information between spectral and compositional similarity can help select the appropriate similarity index when selecting similar samples from a spectral library for prediction.

Association between Toll-like receptor 4 Asp299Gly polymorphism and coronary heart disease susceptibility.

Published data on the association between Toll-like receptor 4 (TLR4) Asp299Gly polymorphism and coronary heart disease (CHD) susceptibility are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. English-language studies were identified by searching PubMed and Embase databases (up to November 2016). All epidemiological studies were regarding Caucasians because no TLR4 Asp/Gly and Gly/Gly genotypes have been detected in Asians. A total of 20 case-control studies involving 14,416 cases and 10,764 controls were included in the meta-analysis. Overall, no significant associations were found between TLR4 Asp299Gly polymorphism and CHD susceptibility in the dominant model (OR=0.89; 95%CI=0.74 to 1.06; P=0.20) pooled in the meta-analysis. In the subgroup analysis by CHD, non-significant associations were found in cases compared to controls. When stratified by control source, no significantly decreased risk was found in the additive model or dominant model. The present meta-analysis suggests that the TLR4 Asp299Gly polymorphism was not associated with decreased CHD risk in Caucasians.

Junctophilin 3 expresses in pancreatic beta cells and is required for glucose-stimulated insulin secretion.

It is well accepted that junctophilin (JPHs) isoforms act as a physical bridge linking plasma membrane and endoplasmic reticulum (ER) for channel crosstalk in excitable cells. Our purpose is to investigate whether JPHs are involved in the proper communication between Ca(2+) influx and subsequent Ca(2+) amplification in pancreatic beta cells, thereby participating in regulating insulin secretion. The expression of JPH isoforms was examined in human and mouse pancreatic tissues, and JPH3 expression was found in both the beta cells. In mice, knockdown of Jph3 (si-Jph3) in islets decreased glucose-stimulated insulin secretion (GSIS) accompanied by mitochondrial function impairment. Si-Jph3 lowered the insulin secretory response to Ca(2+) signaling in the presence of glucose, and reduced [Ca(2+)]c transient amplitude triggered by caffeine. Si-Jph3 also attenuated mitofusin 2 expression, thereby disturbing the spatial organization of ER-mitochondria contact in islets. These results suggest that the regulation of GSIS by the KATP channel-independent pathways is partly impaired due to decrease of JPH3 expression in mouse islets. JPH3 also binds to type 2 ryanodine receptors (RyR2) in mouse and human pancreatic tissues, which might contribute to Ca(2+) release amplification in GSIS. This study demonstrates some previously unrecognized findings in pancreatic tissues: (1) JPH3 expresses in mouse and human beta cells; (2) si-Jph3 in mouse primary islets impairs GSIS in vitro; (3) impairment in GSIS in si-Jph3 islets is due to changes in RyR2-[Ca(2+)]c transient amplitude and ER-mitochondria contact.

HLA-DR3 antigen in the resistance to idiopathic dilated cardiomyopathy.

Idiopathic dilated cardiomyopathy (IDC) has been hypothesized as a multifactorial disorder initiated by an environment trigger in individuals with predisposing human leukocyte antigen (HLA) alleles. Published data on the association between HLA-DR3 antigen and IDC risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Studies were identified by searching the PUBMED and Embase database (starting from June 2015). A total of 19 case-control studies including 1378 cases and 10383 controls provided data on the association between HLA-DR3 antigen and genetic susceptibility to IDC. Overall, significantly decreased frequency of HLA-DR3 allele (OR=0.72; 95%CI=0.58-0.90; P=0.004) was found in patients with IDC compared with controls. When stratified by myocardial biopsy or non-biopsy cases, statistically decreased risk was found for IDC in myocardial biopsy cases (OR=0.69; 95%CI=0.57-0.84; P=0.0003). In the subgroup analysis by ethnicity, borderline statistically significantly decreased risk was found among Europeans from 12 case-control studies (OR=0.76; 95%CI=0.58-1.00; P=0.05). In conclusion, our results suggest that individuals with HLA-DR3 antigen may have a protective effect against IDC.

HLA-DR3 antigen in the resistance to idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) has been hypothesized as a multifactorial disorder initiated by an environment trigger in individuals with predisposing human leukocyte antigen (HLA) alleles. Published data on the association between HLA-DR3 antigen and IDC risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Studies were identified by searching the PUBMED and Embase database (starting from June 2015). A total of 19 case-control studies including 1378 cases and 10383 controls provided data on the association between HLA-DR3 antigen and genetic susceptibility to IDC. Overall, significantly decreased frequency of HLA-DR3 allele (OR=0.72; 95%CI=0.58-0.90; P=0.004) was found in patients with IDC compared with controls. When stratified by myocardial biopsy or non-biopsy cases, statistically decreased risk was found for IDC in myocardial biopsy cases (OR=0.69; 95%CI=0.57-0.84; P=0.0003). In the subgroup analysis by ethnicity, borderline statistically significantly decreased risk was found among Europeans from 12 case-control studies (OR=0.76; 95%CI=0.58-1.00; P=0.05). In conclusion, our results suggest that individuals with HLA-DR3 antigen may have a protective effect against IDC.

Preventive effect of reduced glutathione on contrast-induced nephropathy in elderly patients undergoing coronary angiography or intervention: a randomized, controlled trial.

Coronary angiography can be a high-risk condition for the incidence of contrast-induced nephropathy (CIN) in elderly patients. Reduced glutathione, under a variety of mechanisms, may prevent CIN in this procedure. We prospectively examined whether hydration with reduced glutathione is superior to hydration alone for prevention of CIN in an elderly Han Chinese population. A total of 505 patients (271 males and 234 females) aged 75 years or older who underwent non-emergency coronary angiography or an intervention were randomly divided into two groups. The treatment group received hydration with reduced glutathione (n=262) and the control group received hydration alone (n=243). Serum creatinine and blood urea nitrogen levels were measured prior to coronary angiography and 48 h after this procedure. The primary endpoint was occurrence of CIN, which was defined as 25% or 44.2 µmol/L above baseline serum creatinine levels 48 h after the procedure. The overall incidence of CIN was 6.49% in the treatment group and 7.41% in the control group, with no significant difference between the groups (P=0.68). In subgroup analysis by percutaneous coronary intervention, no significant differences were found between the two groups. In summary, reduced glutathione added to optimal hydration does not further decrease the risk of CIN in elderly patients undergoing coronary angiography or an intervention.

Arginine deiminase PEG20 inhibits growth of small cell lung cancers lacking expression of argininosuccinate synthetase.

BACKGROUND: Some cancers have been shown to lack expression of argininosuccinate synthetase (ASS), an enzyme required for the synthesis of arginine and a possible biomarker of sensitivity to arginine deprivation. Arginine deiminase (ADI) is a microbial enzyme capable of efficiently depleting peripheral blood arginine. METHODS: Argininosuccinate synthetase expression was assessed in human small cell lung cancer (SCLC) by immunohistochemistry (IHC), with expression also assessed in a panel of 10 human SCLC by qRT-PCR and western blot. Proliferation assays and analyses of apoptosis and autophagy assessed the effect of pegylated ADI (ADI-PEG20) in vitro. The in vivo efficacy of ADI-PEG20 was determined in mice bearing SCLC xenografts. RESULTS: Approximately 45% of SCLC tumours and 50% of cell lines assessed were negative for ASS. Argininosuccinate synthetase-deficient SCLC cells demonstrated sensitivity to ADI-PEG20, which was associated with the induction of autophagy and caspase-independent cell death. Arginine deiminase-PEG20 treatment of ASS-negative SCLC xenografts caused significant, dose-dependent inhibition of tumour growth of both small and established tumours. CONCLUSION: These results suggest a role for ADI-PEG20 in the treatment of SCLC, and a clinical trial exploring this therapeutic approach in patients with ASS-negative SCLC by IHC has now been initiated.

Retroviral vectors bearing IgG-binding motifs for antibody-mediated targeting of vascular endothelial growth factor receptors.

Targeting retroviral vectors to tumor vasculature is an important goal of cancer gene therapy. In this study, we report a novel targeting approach wherein IgG-binding peptides were inserted into the Moloney murine leukemia virus (MuLV) envelope (env) protein. The modifications on the viral env included replacement of the entire receptor binding region of the viral env with protein A (or ZZ) domains. The truncated env incorporating IgG-binding motifs (known as proteins) provided the targeting function, while the co-expressed wild-type (WT) env protein enabled viral fusion and cell entry. An anti-human VEGF receptor (Flk-1/KDR) antibody served as a molecular bridge, directing the retroviral vector to the endothelial cell. Hence, the IgG-targeted vectors bound to the Flk-1/KDR antibody which in turn bound to VEGF receptors on Kaposi sarcoma, KSY1, endothelial cells. The net effect was increased viral fusion and infectivity of IgG-bound retroviral vectors when compared to non-targeted vectors bearing WT env alone. These data provide the proof of concept that IgG-binding vector/VEGF receptor antibody complexes may be used to enhance retroviral gene delivery to activated endothelial cells.

[Inhibition of Na+/Ca2+ exchange by tetrapeptide FMRFa in intact rat ventricular myocytes].

AIM: To study the effects of Phe-Met-Arg-Phe-NH2(FMRFa) on Na+/Ca2+ exchange and its specificity for Na+/Ca2+ exchange in rat ventricular myocytes. METHODS: Na+/Ca2+ exchange current and other currents of ion channels were measured using whole cell voltage clamp techniques. RESULTS: A dose-related inhibition of tetrapeptide FMRFa on Na+/Ca2+ exchange was observed in rat ventricular myocytes. Inward and outward INa+/Ca2+ were inhibited by 60.1% and 56.5%, respectively, at highest concentration (100 mumol.L-1) and its IC50 were 20 mumol.L-1 and 34 mumol.L-1 in inward and outward INa+/Ca2+, respectively. Inward and outward INa+/Ca2+ were inhibited 38.7% and 34.9%, respectively, at FMRFa 5 mumol.L-1. FMRFa 5 mumol.L-1 and 20 mumol.L-1 did not affect L-type calcium current, sodium current, transient outward current and inward rectifier potassium current. CONCLUSION: These data indicate that FMRFa is a specific inhibitor of Na+/Ca2+ exchange in intact rat ventricular myocytes.

Identification of regions in the Moloney murine leukemia virus SU protein that tolerate the insertion of an integrin-binding peptide.

Targeting of retroviral vectors to specific cells has been attempted through engineering of the surface (SU) protein of the murine leukemia viruses (MuLVs), but in many cases this has adversely affected protein function and targeted delivery has been difficult to achieve. In this study, we have inserted a 15-mer peptide that binds specifically to the alpha(v)beta(3) integrin into the Moloney MuLV SU protein, including regions that are surface exposed in the crystal structure of the ecotropic receptor-binding domain. We have concentrated in particular on the variable regions VRA, VRB, and VRC, which are responsible for the use of distinct cellular receptors by different MuLV subtypes and therefore may be more likely to accommodate a heterologous binding moiety. Despite these considerations, only 8 of 26 insertion sites were tolerated, including two separate regions in VRA, a cluster of sites in VRC, and previously identified sites at the N-terminus of the protein and in the proline-rich region immediately downstream of the receptor-binding domain. When expressed on retroviral vector particles, all of the viable proteins retained the ability to bind to and transduce murine cells, although the VRC mutants and an insertion in VRA gave reduced binding and titer. Finally, although all of the viable chimeras could bind to alpha(v)beta(3) in a solid-phase binding assay, we were unable to demonstrate expanded tropism for alpha(v)beta(3)-expressing human cells. This study highlights the difficulty of engineering the Moloney MuLV SU protein, even when structural information is available, and provides guidelines for the insertion of peptide ligands into the SU protein.

Class III anti-arrhythmia drug E-4031 potentiates Na+/Ca2+ exchange current in rat ventricular myocytes.

AIM: To study the effects of E-4031 on the Na+/Ca2+ exchange currents (INa/Ca). METHODS: The quasi-steady state current-voltage relationship from the isolated rat ventricular myocytes was measured using whole-cell voltage-clamp techniques with a ramp pulse protocol. RESULTS: At potential of mV, E-4031 5, 10, and 20 mumol.L-1 increased Ni(2+)-sensitive current from (0.48 +/- 0.12), to (0.78 +/- 0.20), (0.96 +/- 0.16), and (1.15 +/- 0.13) pA/pF, respectively; tetradecanoylphorbol acetate (TPA) 50 nmol.L-1 increased Ni(2+)-sensitive current from (0.60 +/- 0.16) to (1.33 +/- 0.25) pA/pF. Tamoxifen 20 mumol.L-1 completely prevented the current changes induced by E-4031 and TPA. CONCLUSION: E-4031 stimulates the Na+/Ca2+ exchange via a protein kinase C-dependent pathway.

Screening of serum autoantibodies to cardiac beta1-adrenoceptors and M2-muscarinic acetylcholine receptors in 408 healthy subjects of varying ages.

Autoantibodies to cardiac beta1-adrenoceptors and M2-muscarinic receptors have mainly been found in the sera of patients with idiopathic dilated cardiomyopathy (DCM). In order to elucidate the pathological significance of these autoantibodies in DCM, it is necessary to understand their characteristic distribution in a healthy population of different genders and ages. The peptides corresponding to the sequences of the second extracellular loops of the human beta1-adrenoceptor and M2-muscarinic receptors were therefore used as antigens to screen the sera of 408 healthy subjects of different ages (ranging from 0.5 to 85 years). Of 408 sera, 41 (10.0%) and 46 (11.3%) recognized the beta1-adrenoceptor and M2-muscarinic receptor peptides respectively. Of the positive sera for beta1-adrenoceptors and M2-muscarinic receptors, up to 63.4% and 56.5% had both anti-beta1-adrenoceptor and anti-M2-muscarinic receptor autoantibodies respectively. The antibody titres of the positive sera of healthy subjects were all of a low level, with a geometric mean titre of 1:42+/-1.9 for anti-beta1-adrenoceptor antibodies and 1:51+/-1.7 for anti-M2-muscarinic receptor antibodies. The frequency of occurrence of autoantibodies to both receptors in the sera of healthy subjects increased significantly with age. In conclusion, the autoantibodies to beta1-adrenoceptors and M2-muscarinic receptors in the sera of healthy subjects are characterized by a low frequency of occurrence and low titre, with the frequency of occurrence increasing with age.

Na+/Ca2+ exchange current in myocytes isolated from rat hypertrophied heart.

Effects of myocardial hypertrophy on the Na+/Ca2+ exchange current in isolated rat cardiac myocytes were investigated, using whole cell patch techniques. Goldblatt 2-kidney, one-clip technique was used to induce cardiomyocyte hypertrophy. The results demonstrated that the Ni(2+)-sensitive Na+/Ca2+ exchange current density was larger in hypertrophied cells than that in normal cells. At a holding potential of mV, the outward current densities were 1.53 +/- 0.31 pA/pF in normal cells and 2.62 +/- 0.53 pA/pF in hypertrophied cells (P < 0.01). At a holding potential of -100 mV, the inward current densities were 0.42 +/- 0.14 pA/pF in normal cells and 1.12 +/- 0.33 pA/pF in hypertrophied cells (P < 0.001). The results suggest that during myocardial hypertrophy the Na+/Ca2+ exchange current is significantly increased.

Inhibition of myocardial inward rectifier potassium current by propylbutyldopamine.

AIM: To study the effects of propylbutyldopamine (PBDA) on the inward rectifier potassium current (Ik1). METHODS: The quasi-steady state current-voltage relationship from the isolated guinea pig ventricular cells were measured using whole-cell patch-clamp techniques with a slow ramp depolarization (8 mV.s-1). RESULTS: PBDA 5, 50, and 100 mumol.L-1 concentration-dependently reduced the inward rectifier potassium current. PBDA blocked Ik1 in guinea pig ventricular cells. The effect of PBDA was not blocked by the selective dopamine D2-receptor blocker, domperidone. CONCLUSION: PBDA inhibited Ik1 directly, independent of the dopamine D2-receptor.

Dicaffeoylquinic and dicaffeoyltartaric acids are selective inhibitors of human immunodeficiency virus type 1 integrase.

Current pharmacological agents for human immunodeficiency virus (HIV) infection include drugs targeted against HIV reverse transcriptase and HIV protease. An understudied therapeutic target is HIV integrase, an essential enzyme that mediates integration of the HIV genome into the host chromosome. The dicaffeoylquinic acids (DCQAs) and the dicaffeoyltartaric acids (DCTAs) have potent activity against HIV integrase in vitro and prevent HIV replication in tissue culture. However, their specificity against HIV integrase in cell culture has been questioned. Thus, the ability of the DCQAs and DCTAs to inhibit binding of HIV type 1 (HIV-1) gp120 to CD4 and their activities against HIV-1 reverse transcriptase and HIV RNase H were studied. The DCQAs and DCTAs inhibited HIV-1 integrase at concentrations between 150 and 840 nM. They inhibited HIV replication at concentrations between 2 and 12 microM. Their activity against reverse transcriptase ranged from 7 microM to greater than 100 microM. Concentrations that inhibited gp120 binding to CD4 exceeded 80 microM. None of the compounds blocked HIV-1 RNase H by 50% at concentrations exceeding 80 microM. Furthermore, when the effects of the DCTAs on reverse transcription in acutely infected cells were measured, they were found to have no activity. Therefore, the DCQAs and DCTAs exhibit > 10- to > 100-fold specificity for HIV integrase, and their activity against integrase in biochemical assays is consistent with their observed anti-HIV activity in tissue culture. Thus, the DCQAs and DCTAs are a potentially important class of HIV inhibitors that act at a site distinct from that of current HIV therapeutic agents.

Effects of norepinephrine and isopentenyladenosine on Na+/Ca2+ exchange currents in isolated guinea pig ventricular myocytes.

AIM: To study the effects of norepinephrine (NE) and isopentenyladenosine (Iso) on Na+/Ca2+ exchange currents and the receptor mechanism. METHODS: The quasi-steady state current-voltage relationship from the isolated guinea pig ventricular myocytes was measured using whole-cell voltage-clamp techniques with a ramp pulse protocol. RESULTS: At potential of +50 mV, NE 0.005, 0.05, and 5 mumol.L-1 increased the Ni(2+)-sensitive current by 29% +/- 9%, 72% +/- 11%, and 124% +/- 31.4%, respectively; Iso 1.5, 150, and 1500 nmol.L-1 caused increases in the Ni(2+)-sensitive current by 2.8% +/- 2.8%, 56% +/- 13%, and 102% +/- 12%, respectively. Propranolol 10 mumol.L-1 completely inhibited the current changes induced by NE and Iso while phentolamine 50 mumol.L-1 showed no effects. CONCLUSION: NE and Iso increased the Na+/Ca2+ exchange currents via stimulation of cardiac beta-adrenoceptor.

Blocking effects of phentolamine on L-type calcium current and ATP-sensitive potassium current in guinea pig ventricular myocytes.

AIM: To study the effect of phentolamine on L-type calcium currents (ICa) and ATP-sensitive K+ currents (IK,ATP) in ventricular myocytes. METHODS: ICa and IK,ATP were observed using patch clamp techniques in whole-cell recording configuration. RESULTS: Phentolamine reduced ICa of ventricular myocytes in concentration-dependent and voltage-independent manners. Phentolamine 5, 25, and 100 mumol.L-1 decreased ICa from 370 +/- 99 nA to 310 +/- 95 nA (17% block, n = 6, P < 0.01), from 230 +/- 98 nA to 180 +/- 73 nA (23% block, n = 5, P < 0.05), and from 293 +/- 66 nA to 206 +/- 44 nA (30% block, n = 5, P < 0.01), respectively, without affecting the current-voltage relationship. Prazosin 100 mumol.L-1 and yohimbine 100 mumol.L-1, which were specific blockers of alpha 1 and alpha 2 adrenoceptors respectively, did not show the inhibitory effect on ICa. Phentolamine 100 mumol.L-1 also inhibited the IK,ATP induced by 2, 4-dinitrophenol (DNP) at 0 mV from 3.2 +/- 0.6 nA to 0.8 +/- 0.5 nA (75% block, n = 4, P < 0.01). CONCLUSION: Phentolamine directly inhibits ICa and IK,ATP in guinea pig ventricular myocytes.

Effects of dopexamine hydrochloride on calcium channels in isolated guinea pig ventricular myocytes.

The mechanisms responsible for the cardiac positive inotropic effects of dopexamine hydrochloride, a combined dopamine receptor agonist at both D1-receptors and beta 2-adrenoceptors, were studied. The calcium channel currents were recorded using whole-cell patch clamp technique in isolated guinea pig ventricular myocytes. At a holding potential of -40 mV, cells were depolarized to 0 mV for 400 ms at a frequency of 0.2 Hz. Dopexamine hydrochloride at doses of 5, 50 and 100 microM increased the verapamil-sensitive Ca2+ inward current by 109, 147 and 194%, respectively. The effects of dopexamine hydrochloride on Ca2+ current reached its maximum at 5 min and partially recovered after washout of the drugs. The increased Ca2+ current induced by dopexamine hydrochloride was completely inhibited by 20 microM propranolol, a beta-adrenoceptor antagonist, and was not antagonized by 20 microM of SCH23390, a highly selective D1-receptor antagonist. These results suggest that the cardiac positive inotropic effects of dopexamine hydrochloride are brought about by the increase of Ca2+ current via stimulation of beta 2-adrenoceptors.

Structure-based design and synthesis of substituted 2-butanols as nonpeptidic inhibitors of HIV protease: secondary amide series.

The design, synthesis, and crystallographic analysis of protein-inhibitor complexes is described for a novel series of nonpeptidic HIV protease (HIV Pr)inhibitors. Beginning with a cocrystal structure of a Phe-Pro peptidomimetic bound to the HIV Pr, design was initiated that resulted in the substituted 2-butanol compound 8 as the lead compound (Ki = 24.5 microM, racemic mixture). Modifications on the initial compound were then made on the basis of its cocrystal structure with HIV Pr and inhibition data, resulting in compounds with enhanced potency against the enzyme (compound 18, Ki = 0.48 microM). These inhibitors were found to bind to the enzyme essentially as predicted on the basis of the original design hypothesis. Stereospecific synthesis of individual enantiomers confirmed the prediction of a binding preference for the S alcohol stereochemistry. Modest antiviral activity was demonstrated for several of the more potent HIV Pr inhibitors in a HIV-1 infected CEM-SS cell line.