2D shear wave elastography combined with age and serum biomarkers prior to kasai surgery predicts native liver survival of biliary atresia infants

BACKGROUND

The prognosis of patients with biliary atresia (BA) after Kasai portoenterostomy (KPE) varies, and precisely predicting the outcomes of KPE before surgery is still challenging.

METHODS

A total of 158 patients who underwent KPE in our hospital were included in this study. The patients in the training cohort were recruited from January 2012 to October 2017 (n = 118), and then, those in the validation cohort were recruited from November 2017 to April 2019 (n = 40). Combined nomogram models were developed based on two-dimensional shear wave elastography (2D SWE) values and other biomarkers. The utility of the proposed models was evaluated by C-index.

RESULTS

2D SWE played a potentially important role in predicting native liver survival (NLS) of BA patients with a C-index of 0.69 (0.63 to 0.75) in the training cohort and 0.76 (0.67 to 0.85) in the validation cohort. The nomogram A based on 2D SWE values, age, gamma-glutamyl transferase (GGT) and aspartate aminotransferase-to-platelet ratio (APRI) had a better C-index in the training cohort [0.74 (0.68-0.80) vs. 0.66 (0.60-0.73), P = 0.017] and in the validation cohort [0.78 (0.70-0.86) vs. 0.60 (0.49-0.71), P = 0.002] than the nomogram B (without 2D SWE). Using risk score developed from nomogram A, we successfully predicted 88.0% (22/25) of patients in the training cohort and 75.0% (9/12) in the validation cohort to have survival time of less than 12 months after KPE.

CONCLUSION

The combined nomogram model based on 2D SWE values, age, GGT and APRI prior to KPE can effectively predict NLS in BA infants.

Effect of Lonicera japonica extract on lactation performance, antioxidant status, and endocrine and immune function in heat-stressed mid-lactation dairy cows

Here, we examined the effects of Lonicera japonica extract (LJE) on lactation performance, antioxidant status, and endocrine and immune function in heat-stressed mid-lactation dairy cows. Twenty-four healthy Chinese Holstein mid-lactation dairy cows, all with similar milk yield (30.0 ± 1.0 kg/d), parity (2.5 ± 0.3), and days in milk (105 ± 5 d) were allocated to 4 groups using a randomized complete block design: a negative control group (without LJE supplementation; CON) and groups that received LJE at 14, 28, and 56 g/d. The experiment lasted 10 wk over a hot summer, with a pre-feeding period of 2 wk. Cows were exposed to heat stress, as the average temperature-humidity index was greater than 72. The results showed that LJE had no effect on respiration rate; however, it reduced the rectal temperature of dairy cows experiencing heat stress in both a linear and quadratic manner; the lowest (39.03°C) was recorded for the LJE-28 group, lower than the CON group. Supplementation with LJE did not affect dry matter intake, milk yield, or milk composition. The majority of biochemical parameters in serum were unaffected by supplementation with different amounts of LJE; the exception was creatinine, which was reduced quadratically. Compared with the CON group, serum triiodothyronine concentrations increased significantly in the LJE-28 group. Addition of LJE to the diet increased thyroxine concentrations quadratically; values peaked at 18.62 ng/mL in the LJE-28 group. Furthermore, supplementation with increasing amounts of LJE quadratically increased the activity of glutathione peroxidase and total antioxidant capacity in serum but decreased concentration of malondialdehyde. Although we detected no differences in the concentrations of IgA, IgM, or cytokines, dairy cows in the LJE-28 group had higher IgG and IL-4 concentrations than did cows in the CON group. Supplementation with LJE increased concentrations of IgG and IL-4 in the serum quadratically but decreased that of IL-2. Finally, heat shock protein 72 concentrations in the serum tended to fall quadratically as the amount of LJE increased. In summary, LJE had no negative effects on lactation performance but helped to alleviate heat stress by improving antioxidant status and promoting endocrine and immune functions. Supplementation with LJE at 28 g/d is recommended for lactating dairy cows experiencing heat stress during hot summers.

Pharmacokinetics of cefquinome in crucian carp (Carassius auratus gibelio) after oral, intramuscular, intraperitoneal, and bath administration

The pharmacokinetics (PK) of cefquinome (CEQ) was studied in crucian carp (Carassius auratus gibelio) after single oral, intramuscular (i.m.), and intraperitoneal (i.p.) administration at a dose of 10 mg/kg body weight and following incubation in a 5 mg/L bath for 5 hr at 25°C. The plasma concentration of CEQ was determined using high-performance liquid chromatography (HPLC). PK parameters were calculated based on mean CEQ concentration using WinNonlin 6.1 software. The disposition of CEQ following oral, i.m., or i.p. administration was best described by a two-compartment open model with first-order absorption. After oral, i.m., and i.p. administration, the maximum plasma concentration (C_max ) values were 1.52, 40.53, and 67.87 μg/ml obtained at 0.25, 0.23, and 0.35 hr, respectively, while the elimination half-life (T_1/2β ) values were 4.68, 7.39, and 6.88 hr, respectively; the area under the concentration-time curve (AUC) values were 8.61, 339.11, and 495.06 μg hr/ml, respectively. No CEQ was detected in the plasma after bath incubation. Therapeutic blood concentrations of CEQ can be achieved in the crucian carp following i.m. and i.p. administration at a dosage of 10 mg/kg once every 2 days.

Pharmacokinetics of enrofloxacin after oral, intramuscular and bath administration in crucian carp (Carassius auratus gibelio)

The pharmacokinetics of enrofloxacin (ENR) was studied in crucian carp (Carassius auratus gibelio) after single administration by intramuscular (IM) injection and oral gavage (PO) at a dose of 10 mg/kg body weight and by 5 mg/L bath for 5 hr at 25°C. The plasma concentrations of ENR and ciprofloxacin (CIP) were determined by HPLC. Pharmacokinetic parameters were calculated based on mean ENR or CIP concentrations using WinNonlin 6.1 software. After IM, PO and bath administration, the maximum plasma concentration (C_max ) of 2.29, 3.24 and 0.36 μg/ml was obtained at 4.08, 0.68 and 0 hr, respectively; the elimination half-life (T_1/2β ) was 80.95, 62.17 and 61.15 hr, respectively; the area under the concentration-time curve (AUC) values were 223.46, 162.72 and 14.91 μg hr/ml, respectively. CIP, an active metabolite of enrofloxacin, was detected and measured after all methods of drug administration except bath. It is possible and practical to obtain therapeutic blood concentrations of enrofloxacin in the crucian carp using IM, PO and bath immersion administration.

Beneficial effects of renal denervation on cardiac angiogenesis in rats with prolonged pressure overload

AIM

Renal denervation (RDN) has beneficial effects on cardiac remodelling and function in resistant hypertension. We aimed to investigate the impact of RDN on cardiac angiogenesis during prolonged pressure overload.

METHODS

Cardiac pressure overload was reproduced by transverse aorta constriction (TAC) procedure in adult Sprague Dawley male rats (n = 35). RDN/sham-RDN procedure was performed in surviving rats at 5 weeks after TAC.

RESULTS

Five weeks post-TAC, transthoracic echocardiography revealed that myocardial hypertrophy occurred in TAC rats, with ejection fraction and fractional shortening not significantly changed. At the end of 10 weeks, cardiac systolic function was preserved in RDN group, but not in sham group. CD31 immunohistochemical staining showed that RDN-treated rats had higher cardiac capillary density than sham rats. However, no significant between-group difference was observed in the kidneys. A decreased protein expression of left ventricle vascular endothelial growth factor (VEGF) was observed in sham group, while RDN attenuated this decrease. Compared with sham, RDN resulted in a higher protein expression of VEGF receptor 2 (VEGFR2) and phosphorylated endothelial nitric oxide synthase (p-eNOS) in the heart.

CONCLUSION

Renal denervation benefits cardiac angiogenesis during sustained pressure overload, involving regulation of VEGF and VEGFR2 expression as well as activation of eNOS.

Activity of cefquinome against extended-spectrum β-lactamase-producing Klebsiella pneumoniae in neutropenic mouse thigh model

Increasing prevalence of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae (K. pneumoniae) is of clinical concern. The objective of our study was to examine the in vivo activity of cefquinome against ESBL-producing K. pneumoniae strain using a neutropenic mouse thigh infection model. Cefquinome kinetics and protein binding in infected neutropenic mice were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Dose-fractionation studies over a 24-h dose range of 2.5-320 mg/kg were administered every 3, 6, 12, or 24 h. The percentage of the dosing interval that the free-drug serum levels exceed the MIC (%fT > MIC) was the PK-PD index that best correlated with cefquinome efficacy (R²  = 86%). Using a sigmoid E_max model, the magnitudes of %fT > MIC producing net bacterial stasis, a 1-log₁₀ kill and a 2-log₁₀ kill over 24 h, were estimated to be 20.07%, 29.57%, and 55.12%, respectively. These studies suggest that optimal cefquinome PK/PD targets are not achieved in pigs, sheep, and cattle at current recommended doses (1˜2 mg/kg). Further studies with higher doses in the target species are needed to ensure therapeutic concentration, if cefquinome is used for treatment of K. pneumoniae infection.

Effects of renin-angiotensin-aldosterone system inhibitors on mortality, hospitalization, and diastolic function in patients with HFpEF. A meta-analysis of 13 randomized controlled trials

AIM

The purpose of this meta-analysis was to evaluate the effects of renin-angiotensin-aldosterone system (RAAS) inhibitors on mortality, hospitalization, diastolic function, and exercise capacity in heart failure with preserved ejection fraction (HFpEF).

METHODS

Thirteen randomized controlled trials (RCTs), totaling 12,532 patients with HFpEF, were selected. All-cause and cardiovascular mortality, all-cause and heart failure-related hospitalization, diastolic function, and the 6-min walk distance were assessed. The risk ratios (RR) of the dichotomous data, weighted mean difference (WMD) of continuous data, and 95 % confidence intervals (CI) were calculated to assess the effects of RAAS inhibitors.

RESULTS

RAAS inhibitors significantly decreased heart failure-related hospitalization (RR 0.89; 95 % CI 0.82-0.97; p = 0.01) and improved the diastolic function, as reflected in a reduced E/e' index (MD -1.38; 95 % CI -2.01 to -0.74; p < 0.0001). However, there were no beneficial effects on all-cause cardiovascular mortality and all-cause hospitalization. Other diastolic parameters had few changes compared with the controls. The 6-min walk distance was not improved by the use of RAAS inhibitors.

CONCLUSION

In patients with HFpEF, RAAS inhibitors decreased heart-failure hospitalization and the E/e' index without affecting mortality, all-cause hospitalization, other diastolic function parameters, and the 6-min walk distance.

Pharmacokinetics of cefquinome in tilapia (Oreochromis niloticus) after a single intramuscular or intraperitoneal administration

The pharmacokinetics of cefquinome was studied in plasma after a single dose (10 mg/kg) of intramuscular (i.m.) or intraperitoneal (i.p.) administration to tilapia (Oreochromis niloticus) in freshwater at 30 °C. Ten fish per sampling point were examined after treatment. The data were fitted to two-compartment open models following both routes of administration. The estimates of total body clearance (CL/F), volume of distribution (Vd/F), and absorption half-life (T1/2ka ) were 0.049 and 0.037 L/h/kg, 0.41 and 0.33 L/kg, and 0.028 and 0.035 h following i.m. and i.p. administration, respectively. After i.m. injection, the elimination half-life (T1⁄2β ) was calculated to be 5.81 h, the maximum plasma concentration (Cmax ) to be 49.40 μg/mL, the time to peak plasma cefquinome concentration (Tmax ) to be 0.14 h, and the area under the plasma concentration-time curve (AUC) to be 204.6 μg h/mL. Following i.p. administration, the corresponding estimates were 6.05 h, 44.39 μg/mL, 0.17 h and 267.8 μg h/mL. The minimum inhibitory concentrations of cefquinome, determined for 30 strains of Streptococcus agalactiae isolated from diseased tilapia, ranged from 0.015 to 0.12 μg/mL. Results from these studies support that 10 mg cefquinome/kg body weight daily could be expected to control tilapia bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of ≤2 μg/mL.

Pharmacokinetics of doxycycline in tilapia (Oreochromis aureus × Oreochromis niloticus) after intravenous and oral administration

The pharmacokinetics of doxycycline was studied in plasma after a single dose (20 mg/kg) of intravenous or oral administration to tilapia (Oreochromis aureus × Oreochromis niloticus) reared in fresh water at 24 °C. Plasma samples were collected from six fish per sampling point. Doxycycline concentrations were determined by high-performance liquid chromatography with a 0.005 μg/mL limit of detection, then were subjected to noncompartmental analysis. Following oral administration, the double-peak phenomenon was observed, and the first (Cmax1 ) and second (Cmax2) peaks were 1.99 ± 0.43 μg/mL at 2.0 h and 2.27 ± 0.38 μg/mL at 24.0 h, respectively. After the intravenous injection, a Cmax2 (12.12 ± 1.97 μg/mL) was also observed, and initial concentration of 45.76 μg/mL, apparent elimination rate constant (λz) of 0.018 per h, apparent elimination half-life (t1/2λz) of 39.0 h, systemic total body clearance (Cl) of 41.28 mL/h/kg, volume of distribution (Vz) of 2323.21 mL/kg, and volume of distribution at steady-state (Vss) of 1356.69 mL/kg were determined, respectively. While after oral administration, the λz, t1/2λz, and bioavailability of doxycycline were 0.009 per h, 77.2 h, and 23.41%, respectively. It was shown that doxycycline was relatively slowly and incompletely absorbed, extensively distributed, and slowly eliminated in tilapia, in addition, doxycycline might undergo enterohepatic recycling in tilapia.

Rigorous analysis of highly tunable cylindrical transverse magnetic mode re-entrant cavities

Cylindrical re-entrant cavities are unique three-dimensional structures that resonate with their electric and magnetic fields in separate parts of the cavity. To further understand these devices, we undertake rigorous analysis of the properties of the resonance using "in-house" developed Finite Element Method (FEM) software capable of dealing with small gap structures of extreme aspect ratio. Comparisons between the FEM method and experiments are consistent and we illustrate where predictions using established lumped element models work well and where they are limited. With the aid of the modeling we design a highly tunable cavity that can be tuned from 2 GHz to 22 GHz just by inserting a post into a fixed dimensioned cylindrical cavity. We show this is possible, as the mode structure transforms from a re-entrant mode during the tuning process to a standard cylindrical transverse magnetic mode.

Pharmacokinetic/pharmacodynamic relationship of cefquinome against Pasteurella multocida in a tissue-cage model in yellow cattle

The cephalosporin antimicrobial drug cefquinome was administered to yellow cattle intravenously (i.v.) and intramuscularly (i.m.) at a dose of 1 mg/kg of body weight in a two-period crossover study. The pharmacokinetic (PK) properties of cefquinome in serum, inflamed tissue-cage fluid (exudate), and noninflamed tissue-cage fluid (transudate) were studied using a tissue-cage model. The in vitro and ex vivo activities of cefquinome in serum, exudate, and transudate against a pathogenic strain of Pasteurella multocida (P. multocida) were determined. A concentration-independent antimicrobial activity of cefquinome was confirmed for levels lower than 4 × MIC. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the time that drug levels remain above the MIC (T > MIC) in serum was 14.10 h after intravenous and 14.46 h after intramuscular dosing, indicating a likely high level of effectiveness in clinical infections caused by P. multocida of MIC 0.04 μg/mL or less. These data may be used as a rational basis for setting dosing schedules, which optimize clinical efficacy and minimize the opportunities for emergence of resistant organisms.

Pharmacokinetic/pharmacodynamic relationship of marbofloxacin against Pasteurella multocida in a tissue-cage model in yellow cattle

The fluoroquinolone antimicrobial drug marbofloxacin was administered to yellow cattle intravenously and intramuscularly at a dose of 2 mg/kg of body weight in a two-period crossover study. The pharmacokinetic properties of marbofloxacin in serum, inflamed tissue-cage fluid (exudate), and noninflamed tissue-cage fluid (transudate) were studied by using a tissue-cage model. The in vitro and ex vivo activities of marbofloxacin in serum, exudate, and transudate against a pathogenic strain of Pasteurella multocida (P. multocida) were determined. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the area under the curve (AUC)/MIC for serum, exudate, and transudate of 155.75, 153.00, and 138.88, respectively, after intravenous dosing and 160.50, 151.00, and 137.63, respectively, after intramuscular dosing. After intramuscular dosing, the maximum concentration/MIC ratios for serum, exudate, and transudate were 21.13, 9.13, and 8.38, respectively. The ex vivo growth inhibition data after intramuscular dosing were fitted to the inhibitory sigmoid Emax equation to provide the values of AUC/MIC required to produce bacteriostasis, bactericidal activity, and elimination of bacteria. The respective values for serum were 17.25, 31.29, and 109.62, and slightly lower values were obtained for transudate and exudate. It is proposed that these findings might be used with MIC50 or MIC90 data to provide a rational approach to the design of dosage schedules which optimize efficacy in respect of bacteriological as well as clinical cures.

Abstract P1-01-09: Which nomograms may be the best for predicting nonsentinel lymph node metastasis in breast cancer patients: a meta-analysis

Background: Axillary lymph node dissection (ALND) is the standard treatment for breast cancer patients with positive sentinel lymph nodes (SLNs). Several nomograms were developed to identify SLN-positive patients with low risk of nonsentinel lymph nodes (NSLNs) metastasis. These nomograms were validated in different populations and it is still unknown which is the best. This study is to present a systemic review and perform a meta-analysis to obtained the pooled AUC (Area Under the receiver-operator Curve) value of each models.

Methods: This review focused on six models: Cambridge, MSKCC, Mayo, MDA, Tenon and Stanford models. A “Pubmed” search and “Web of science” search were conducted and 35 literatures were ultimately included. AUC and the number of patients with positive NSLNs were extracted. Publication bias and heterogeneity were analyzed. AUCs were converted to odds ratios (ORs) for combination. The combined ORs were converted back to AUCs to represent the integrated discriminative capabilities of each models.

Findings: In total, the Cambridge, Mayo, MDA, MSKCC, Stanford and Tenon models were validated in 8, 6, 4, 39, 14 and 15 studies, with 2156, 2431, 843, 8143, 3700 and 3648 patients included, respectively. There were no publication bias or heterogeneity observed in the Cambridge, Mayo, MDA and Tenon models (Table 1). The combined ORs and the corresponding AUCs of each models were listed as follow: Cambridge (OR = 3.86, AUC = 0.71), Mayo (OR = 3.71, AUC = 0.71), MSKCC (OR = 3.47, AUC = 0.70), MDA(OR = 3.44, AUC = 0.70), Tenon (OR = 3.46, AUC = 0.70) and Stanford (OR = 2.92, AUC = 0.67). For each of the predictive models, both fixed and random effect models were used to calculate the combined OR. The presence of larger difference between the fixed and random effect analysis suggests small study effects, rendering the meta-analysis relatively less reliable. The combined ORs were identical when fixed and random effect models were used in the Cambridge and MDA models, suggesting that there was no small study effects in these two models.

Proteasome inhibitor bortezomib overcomes P-gp-mediated multidrug resistance in resistant leukemic cell lines

INTRODUCTION

To study the effect of bortezomib alone or in combination with daunorubicin (DNR) on an mdr1 single-factor drug-resistant leukemia cell line K562/MDR1, a multifactor-resistant cell line K562/A02, a drug-sensitive cell line K562, and primary cells from acute myeloid leukemia patients.

METHODS

The cell lines were exposed to bortezomib, DNR, and bortezomib plus DNR, and cell proliferation, cell cycle, apoptosis rate, and expression of MDR1/BCL2 were analyzed.

RESULTS

Bortezomib potently inhibited growth and increased the apoptosis rate in the cell lines. In K562/MDR1 and K562/A02, the calcium channel blocker verapamil reduced the 50% inhibitory concentration and apoptosis rate of DNR, a P-gp protein substrate, but not of bortezomib. Bortezomib plus DNR had synergistic effect on antiproliferation (synergistic ratio > 1). Apoptosis was substantially more increased by the combination of two drugs than by bortezomib alone. Bortezomib arrested the cell cycles of three cell lines at the G2/M stage, decreased BCL2 mRNA expression, but did not affect MDR1 mRNA levels. The antiproliferative role of bortezomib was also confirmed in primary leukemia cells.

CONCLUSION

Bortezomib is a promising potential therapy for acute leukemia, especially mdr1 drug-resistant leukemia.

Short-term stimulation of the thiazide-sensitive Na+-Cl- cotransporter by vasopressin involves phosphorylation and membrane translocation

Vasopressin influences salt and water transport in renal epithelia. This is coordinated by the combined action of V2 receptor-mediated effects along distinct nephron segments. Modulation of NaCl reabsorption by vasopressin has been established in the loop of Henle, but its role in the distal convoluted tubule (DCT), an effective site for fine regulation of urinary electrolyte composition and the target for thiazide diuretics, is largely unknown. The Na+-Cl- cotransporter (NCC) of DCT is activated by luminal trafficking and phosphorylation at conserved NH2-terminal residues. Here, we demonstrate the effects of short-term vasopressin administration (30 min) on NCC activation in Brattleboro rats with central diabetes insipidus (DI) using the V2 receptor agonist desmopressin (dDAVP). The fraction of NCC abundance in the luminal plasma membrane was significantly increased upon dDAVP as shown by confocal microscopy, immunogold cytochemistry, and Western blot, suggesting increased apical trafficking of the transporter. Changes were paralleled by augmented phosphorylation of NCC as detected by antibodies against phospho-threonine and phospho-serine residues (2.5-fold increase at Thr53 and 1.4-fold increase at Ser71). dDAVP-induced phosphorylation of NCC, studied in tubular suspensions in the absence of systemic effects, was enhanced as well (1.7-fold increase at Ser71), which points to the direct mode of action of vasopressin in DCT. Changes were more pronounced in early (DCT1) than in late DCT as distinguished by the distribution of 11beta-hydroxysteroid dehydrogenase 2 in DCT2. These results suggest that the vasopressin-V(2) receptor-NCC signaling cascade is a novel effector system to adjust transepithelial NaCl reabsorption in DCT.

Construction and analysis of cDNA library of Necator americanus third stage larvae

OBJECTIVE

To obtain the genetic information on Necator americanus and to search for the purpose genes.

METHODS

mRNA was isolated from the third stage larvae of Necator americanus maintained in hamsters. Double strand cDNA was synthesized and ligated to lambda ZAPII vector to construct the cDNA library. Expressed sequence tages (ESTs) were obtained by single pass sequencing of randomly isolated cDNA clones from the established library.

RESULTS

A cDNA library of N. americanus was successfully constructed with high recombinant efficiency. The titer of unamplified library was 1 x 10(7). The insert size was about 750-3,000 bp. Of 11 ESTs obtained from the library, 7 have a significant homology with certain functional genes.

CONCLUSION

A high quality and high representative cDNA library of N. americanus was constructed at the first time and some functional genes were identified from the library by ESTs.

[Sequencing of cytochrome C oxidase 1 gene of Ancylostoma duodenale and Necator americanus]

AIM

To identify the genetic diversity between Ancylostoma duodenale and Necator americanus.

METHODS

Mitochondrial cytochrome C oxidase subunit 1 (CO1) gene was amplified from genomic DNA of human hookworms collected from infected patients in Hejiang County, Sichuan Province, and the purified PCR products were directly sequenced by using Licor auto-sequencer.

RESULTS

The PCR products were about 700 bp. Alignment of CO1 gene fragment sequences showed 89.7% similarity between Ancylostoma duodenale and Necator americanus, but still certain nucleotide variations (10.3%) existed.

CONCLUSION

CO1 gene sequence can be used as a marker to identify the two species of human hookworms.

Ivermectin, an unconventional agonist of the glycine receptor chloride channel

The effects of the antihelmintic, ivermectin, were investigated in recombinantly expressed human alpha(1) homomeric and alpha(1)beta heteromeric glycine receptors (GlyRs). At low (0.03 microm) concentrations ivermectin potentiated the response to sub-saturating glycine concentrations, and at higher (> or =0.03 microm) concentrations it irreversibly activated both alpha(1) homomeric and alpha(1)beta heteromeric GlyRs. Relative to glycine-gated currents, ivermectin-gated currents exhibited a dramatically reduced sensitivity to inhibition by strychnine, picrotoxin, and zinc. The insensitivity to strychnine could not be explained by ivermectin preventing the access of strychnine to its binding site. Furthermore, the elimination of a known glycine- and strychnine-binding site by site-directed mutagenesis had little effect on ivermectin sensitivity, demonstrating that the ivermectin- and glycine-binding sites were not identical. Ivermectin strongly and irreversibly activated a fast-desensitizing mutant GlyR after it had been completely desensitized by a saturating concentration of glycine. Finally, a mutation known to impair dramatically the glycine signal transduction mechanism had little effect on the apparent affinity or efficacy of ivermectin. Together, these findings indicate that ivermectin activates the GlyR by a novel mechanism.

Clinical and familial study of arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE

To explore the characteristics of arrhythmogenic right ventricular cardiomyopathy (ARVC).

METHODS

Seven patients with arrhythmogenic right ventricular cardiomyopathy and 34 members of three families were studied. All patients and family members underwent history collection, clinical examination, electrocardiogram (ECG), two-dimensional echocardiography (2-DE) and a signal averaging electrocardiogram. Programmed ventricular stimulation was performed in five patients.

RESULTS

All patients and family members had normal morphologic characteristics and normal function of the left ventricular by 2-DE. Fourteen persons had abnormal findings indicating ARVC. Five had enlargement of the right ventricular with diffused hypocontractility, eight had thin and systolic bulging in the focal anterior wall with hypokinesia and one had bulging of the inferior wall. Twenty-five persons (seven patients and 18 family members) had abnormal findings in ECG. Positive ventricular late potential was recorded in 13 persons (six patients). Two to three monomorphic ventricular tachycardia (VT) with left bundle branch block (LBBB) configurations were induced in five patients. Ventricular fibrillation was induced in two patients during the electrophysiologic study (EPS). Five patients had very high pacing threshold and/or ineffective pacing in one or many regions of the right ventricle. Two members of one family died suddenly. One member was a dwarf with ARVC. Spontaneous VT with a left bundle branch block (LBBB) configuration was recorded in five patients, polymorphic VT with extremely short coupling interval in one, and premature ventricular complexes with LBBB configuration in 12 (six patients).

CONCLUSION

Our familial study strongly suggests that ARVC may be a hereditary disease and it is helpful in the diagnosis and detection of ARVC. The most common manifestations were abnormal structure and function of the right ventricle and abnormal ECG of repolarization and ventricular arrhythmia which originates from the right ventricle.

A single beta subunit M2 domain residue controls the picrotoxin sensitivity of alphabeta heteromeric glycine receptor chloride channels

This study investigated the residues responsible for the reduced picrotoxin sensitivity of the alphabeta heteromeric glycine receptor relative to the alpha homomeric receptor. By analogy with structurally related receptors, the beta subunit M2 domain residues P278 and F282 were considered the most likely candidates for mediating this effect. These residues align with G254 and T258 of the alpha subunit. The T258A, T258C and T258F mutations dramatically reduced the picrotoxin sensitivity of the alpha homomeric receptor. Furthermore, the converse F282T mutation in the beta subunit increased the picrotoxin sensitivity of the alphabeta heteromeric receptor. The P278G mutation in the beta subunit did not affect the picrotoxin sensitivity of the alphabeta heteromer. Thus, a ring of five threonines at the M2 domain depth corresponding to alpha subunit T258 is specifically required for picrotoxin sensitivity. Mutations to alpha subunit T258 also profoundly influenced the apparent glycine affinity. A substituted cysteine accessibility analysis revealed that the T258C sidechain increases its pore exposure in the channel open state. This provides further evidence for an allosteric mechanism of picrotoxin inhibition, but renders it unlikely that picrotoxin (as an allosterically acting 'competitive' antagonist) binds to this residue.

Cardiac and vascular effects of nitric oxide synthase inhibition in lipopolysaccharide-treated rats

In the present study, intraperitoneal injection of lipopolysaccharide (10 mg/kg) to anaesthetized rats produced a gradual fall in mean arterial pressure in 6 h. Aortic rings from lipopolysaccharide-treated rats showed a significant reduction in the contractile response to vasoconstrictors. Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME) or aminoguanidine, two nitric oxide synthase (NOS) inhibitors, abolished this vascular hyporeactivity. In ventricular myocytes isolated from lipopolysaccharide-treated rats, both electrically induced Ca(2+) transients and the intracellular Ca(2+) response to beta-adrenergic stimulation were significantly depressed when compared with those recorded from myocytes from sham control rats. L-NAME and aminoguanidine alone had no effects on electrically stimulated Ca(2+) transients in ventricular myocytes either from control or lipopolysaccharide-treated rats. However, these two NOS inhibitors augmented the intracellular Ca(2+) response to beta-adrenergic stimulation in myocytes from lipopolysaccharide-treated rats, but not in control myocytes. In addition, 1H-[1,2,4]oxadiazolo[4, 3-a]quinoxalin-1-one (ODQ), an inhibitor of nitric oxide (NO)-sensitive guanylyl cyclase, also reversed the intracellular Ca(2+) hyporesponsiveness to beta-adrenergic stimulation in myocytes from lipopolysaccharide-treated rats. In cardiac myocytes from lipopolysaccharide-rats pretreated with aminoguanidine, the intracellular Ca(2+) hyporesponsiveness to beta-adrenergic stimulation was abolished. However, there still existed a depressed Ca(2+) response to electrical field stimulation. These data indicate that NO following lipopolysaccharide stimulation contributes to vascular hyporeactivity and the depressed intracellular Ca(2+) response to beta-adrenergic stimulation in lipopolysaccharide-treated rats, but is not responsible for the reduced Ca(2+) response to electrical stimulation in our experimental conditions.

[Automatic modulation of refractoriness of His-Purkinje system during atrioventricular nodal reentrant tachycardia]

OBJECTIVE

To illustrate the automatic modulation of refractoriness of His-Purkinje system during atrioventricular nodal reentrant tachycardia (AVNRT) and to discuss the possible mechanisms.

METHODS

Programmed electrical stimulations were performed in high right atrium (HRA) in 8 patients with AVNRT before ablation to induce tachycardia and electrocardiagraphic recordings were done synchronically when AVNRT appeared.

RESULTS

All the patients had 2:1 atrioventricular (A-V) conduction when AVNRT began, 2 of whom were blocked below His bundle, 5 above His bundle and 1 unclear. After a duration of 14.03 +/- 10.03 s of 2:1 A-V conduction, 1:1 A-V conduction with bundle banch block appeared, 3 of which were right bundle branch block (RBBB), 3 left bundle branch block (LBBB), and 2 with both. Bundle branch block disappeared after a duration of 6.87 +/- 11.26 s.

CONCLUSION

Effective refractory period (ERP) of His-Purkinje system at the beginning of AVNRT was modulated automatically within less than 30-60 s and thus facilitated nodal-ventricular conduction. The mechanism of this is electrical remodeling.

Inhibition of the transcription factor nuclear factor-kappa B by adenoviral-mediated expression of I kappa B alpha M results in tumor cell death

BACKGROUND

The activation of transcription factor nuclear factor-kappa B (NF-kappa B) by extracellular stimuli has been shown to protect cells from apoptotic cell death. Inhibition of NF-kappa B activity should result in increased tumor cell killing in response to apoptotic stimuli. This study evaluated the effect of inhibition of NF-kappa B on a series of sarcoma and normal cell lines.

METHODS

Human sarcoma cell lines (HT1080, SKLMS-1, and MFH) and normal cell lines (NLF and BSMC) were infected with an adenoviral dominant-negative mutant Ad5I kappa B alpha M in vitro. Control cells were infected with the empty adenoviral vector and mock-infected with media alone. Viable cell counts were determined by microscopic evaluation on days 1 to 6 after infection. Cell proliferation was determined at 48 hours by MTT (1-[4,5-dimethylthiazol-2-yl]-3,5-dephenylformazan) assay.

RESULTS

All cell lines showed evidence of successful adenoviral infection as evidenced by the infection of all cell lines with the adenoviral marker gene Ad5 LacZ. All the tumor cells were found to have a significant decrease in cell viability and proliferation after treatment with the Ad5I kappa B alpha M gene compared with both mock-infected cells and cells infected with empty vector (P < .0001). The normal cell lines, although able to be successfully infected, did not show a significant decrease in cell viability or proliferation with adenoviral-mediated I kappa B alpha M infection.

CONCLUSIONS

Inhibition of NF-kappa B through adenoviral-mediated infection of the dominant-negative inhibitor I kappa B alpha M resulted in a significant decrease in tumor cell viability and proliferation while having no deleterious effect on normal cell lines. The Ad5I kappa B alpha M gene therefore could be potentially used as a clinical treatment for patients with soft-tissue sarcoma.

[The relationship of lung function and heart function of RHD patients in different period]

OBJECTIVE

To investigate the relationship of heart function and lung function in RHD patients.

METHODS

We compared heart posterior-anterior film, lung function test results, PaO(2) and O(2) Sat of blood gas analysis before and after motion before operation, early postoperation, late postoperation, according to heart function and cardiothoracic ratio in 98 RHD patients.

RESULTS

With worsening of heart function and enlargement of cardiothoracic ratio, lung function worsened too. PaO(2) and O(2) Sat did not change apparently. The lung function of early postoperation did not improve significantly. The lung function improved gradually with better heart function and shortening of heart in later postoperation. But small air way obstruction and diffuse function and function residue volume changed slowly.

CONCLUSIONS

Heart function affects the lung function directly. They were positively correlated.

Effects of acupuncture on the levels of endothelin, TXB2, and 6-keto-PGF1 alpha in apoplexy patients

In order to delve into the mechanism governing the treatment of apoplexy by acupuncture at yangming channel points as main points, we observed the changes in the endothelin (ET) level in plasma, TXB2 and 6-Keto-PGF1 alpha levels in urine in convalescent apoplexy patients during acupuncture treatment. The results showed that the ET level in plasma in convalescent apoplexy patients was significantly higher than that in healthy subjects (P < 0.05), and the ET level in plasma in patients was decreased after one course of acupuncture treatment. It was found that before treatment the TXB2 level in urine in apoplexy patients was significantly higher than in healthy subjects, and the 6-Keto-PGF1 alpha level in urine in the patients was significantly lower than that in healthy subjects, with an increased ratio of TXB2 to 6-Keto-PGF1 alpha. After acupuncture treatment, the TXB2 level in urine was lowered with a decrease in the ratio of TXB2 to 6-Keto-PGF1 alpha. All this indicated that one of the mechanisms governing acupuncture treatment of apoplexy acupuncture at yangming channel points as main points was that acupuncture could produce therapeutic effects by adjusting the imbalance of important vaso-active substances, ET, TXA2, and PGI2.

On the mechanism of RecA-mediated repair of double-strand breaks: no role for four-strand DNA pairing intermediates

RecA protein will bind to a gapped duplex DNA molecule and promote a DNA strand exchange with a second homologous linear duplex. A double-strand break in the second duplex is efficiently bypassed in the course of these reactions. We demonstrate that the bypass of double-strand breaks is not explained by a mechanism involving homologous interactions between two duplex DNA molecules, but instead requires the ATP-mediated generation of DNA torsional stress brought about by the action of RecA. The results suggest new pathways for the repair of double-strand breaks and underline the need for new paradigms to explain the alignment of homologous DNAs during genetic recombination.

RecA as a motor protein. Testing models for the role of ATP hydrolysis in DNA strand exchange

ATP hydrolysis (by RecA protein) fundamentally alters the properties of RecA protein-mediated DNA strand exchange reactions. ATP hydrolysis renders DNA strand exchange unidirectional, greatly increases the lengths of hybrid DNA created, permits the bypass of heterologous DNA insertions in one or both DNA substrates, and is absolutely required for exchange reactions involving four DNA strands. There are at least two viable models to explain how ATP hydrolysis is coupled to DNA strand exchange so as to bring about these effects. The first couples ATP hydrolysis to a redistribution of RecA monomers within a RecA filament. The second couples ATP hydrolysis to a facilitated rotation of the DNA substrates. The RecA monomer redistribution model makes the prediction that heterology bypass should not occur if the single-stranded DNA substrate is linear. The facilitated DNA rotation model predicts that RecA protein should promote the separation of paired DNA strands within a RecA filament if one of them is contiguous with a length of DNA being rotated about the filament exterior. Here, a facile bypass of heterologous insertions with linear DNA substrates is demonstrated, providing evidence against a role for RecA monomer redistribution in heterology bypass. In addition, we demonstrate that following a four-strand DNA exchange reaction, a distal segment of DNA hundreds of base pairs in length can be unwound in a nonreciprocal phase of the reaction, consistent with the direct coupling of an ATP hydrolytic motor to the proposed DNA rotation.

RecA filament dynamics during DNA strand exchange reactions

The role of ATP hydrolysis in RecA protein-mediated DNA strand exchange reactions remains controversial. Competing models suggest that ATP hydrolysis is coupled either to a simple redistribution of RecA monomers within a filament to repair filament discontinuities, or more directly to rotation of the DNA substrates to drive branch movement unidirectionally. Here, we test key predictions of the RecA redistribution idea. When ATP is hydrolyzed, DNA strand exchange is accompanied by a RecA exchange reaction, between free and bound RecA protomers in the interior of RecA filaments, that meets a central prediction of the model. The RecA protomer exchange is not required for, and does not occur during, the "search for homology" in which the single-stranded DNA within a RecA-ssDNA nucleoprotein filament is homologously aligned with the duplex DNA. Instead, the RecA exchange is triggered by the completion of strand exchange (a strand switch to generate a hybrid DNA product) in any given segment of the filament. In effect, formation of hybrid DNA leads to a change in filament conformation to one with properties approximating those of RecA filaments bound to double-stranded DNA. Addition of the RecA K72R mutant protein to a reaction with the wild type protein leads to the formation of mixed filaments and a poisoning of the DNA strand exchange reaction. Under some conditions, a facile RecA protomer exchange is observed, and significant ATP is hydrolyzed, even though DNA strand exchange is entirely blocked by the mutant protein. A redistribution of RecA protomers coupled to ATP hydrolysis is not sufficient in itself to explain how ATP hydrolysis facilitates DNA strand exchange. A RecA protomer exchange may nevertheless play an important role in the DNA strand exchange process.

RecA protein filaments: end-dependent dissociation from ssDNA and stabilization by RecO and RecR proteins

RecA protein filaments formed on circular (ssDNA) in the presence of ssDNA binding protein (SSB) are generally stable as long as ATP is regenerated. On linear ssDNA, stable RecA filaments are believed to be formed by nucleation at random sites on the DNA followed by filament extension in the 5' to 3' direction. This view must now be enlarged as we demonstrate that RecA filaments formed on linear ssDNA are subject to a previously undetected end-dependent disassembly process. RecA protein slowly dissociates from one filament end and is replaced by SSB. The results are most consistent with disassembly from the filament end nearest the 5' end of the DNA. The bound SSB prevents re-formation of the RecA filaments, rendering the dissociation largely irreversible. The dissociation requires ATP hydrolysis. Disassembly is not observed when the pH is lowered to 6.3 or when dATP replaces ATP. Disassembly is not observed even with ATP when both the RecO and RecR proteins are present in the initial reaction mixture. When the RecO and RecR proteins are added after most of the RecA protein has already dissociated, RecA protein filaments re-form after a short lag. The newly formed filaments contain an amount of RecA protein and exhibit an ATP hydrolysis rate comparable to that observed when the RecO and RecR proteins are included in the initial reaction mixture. The RecO and RecR proteins thereby stabilize RecA filaments even at the 5' ends of ssDNA, a fact which should affect the recombination potential of 5' ends relative to 3' ends. The location and length of RecA filaments involved in recombinational DNA repair is dictated by both the assembly and disassembly processes, as well as by the presence or absence of a variety of other proteins that can modulate either process.

Modelling of a photoacoustic probe designed for medical applications

A model is presented describing the thermoelastic photoacoustic interaction in a layered medium within a transparent fluid, where a polymer transducer is used for the detection of ultrasonic pulses. By taking the optical absorption coefficient and finite layer thickness into account, the amplitude and shape of photoacoustic transients are calculated for both forward and backward travelling directions. Additionally, photoacoustic transient interaction with the PVDF transducer has been characterised using a discrete-time algorithm for the transducer response. Good agreement with experimental waveforms are demonstrated, so that this may form the basis of system characterisation when miniature laser-ultrasound probes are used in various applications.

RecA protein dynamics in the interior of RecA nucleoprotein filaments

We characterize aspects of the conformation and dynamic state of RecA filaments when bound to dsDNA that are specifically linked to the presence of the second of the two bound DNA strands. Filaments bound to dsDNA exhibit a facile exchange between free and bound RecA monomers or oligomers in the filament interior that is not seen on ssDNA. The RecA mutant K72R, which binds but does not hydrolyze ATP, forms mixed filaments with wild type RecA protein under some conditions. In the presence of dATP, mixed filaments are formed on dsDNA or ssDNA in which the RecA K72R content approximately reflects the proportion of the K72R mutant in the total RecA protein present when the filament is formed. In the presence of ATP, mixed filaments are formed on dsDNA, but the mutant protein strongly inhibits the binding of wtRecA protein to single-stranded DNA. When RecA K72R is added to pre-formed filaments containing only wild-type RecA protein on single-stranded DNA, little of the mutant protein exchanges into the filament. Exchange occurs readily, however, when the filament is bound to double-stranded DNA. The presence of a second DNA strand in RecA-dsDNA filaments produces as altered and more dynamic filament state relative to filaments formed on single-stranded DNA. The results point to a substantial alteration in filament state when synapsis occurs during RecA protein-mediated DNA strand exchange.

DNA strand exchange promoted by RecA K72R. Two reaction phases with different Mg2+ requirements

Replacement of lysine 72 in RecA protein with arginine produces a mutant protein that binds but does not hydrolyze ATP. The protein nevertheless promotes DNA strand exchange (Rehrauer, W. M., and Kowalczykowski, S. C. (1993) J. Biol. Chem. 268, 1292-1297). With RecA K72R protein, the formation of the hybrid DNA product of strand exchange is greatly affected by the concentration of Mg2+ in ways that reflect the concentration of a Mg.dATP complex. When Mg2+ is present at concentrations just sufficient to form the Mg.dATP complex, substantial generation of completed product hybrid DNAs over 7 kilobase pairs in length is observed (albeit slowly). Higher levels of Mg2+ are required for optimal uptake of substrate duplex DNA into the nucleoprotein filament, indicating that the formation of joint molecules is facilitated by Mg2+ levels that inhibit the subsequent migration of a DNA branch. We also show that the strand exchange reaction promoted by RecA K72R, regardless of the Mg2+ concentration, is bidirectional and incapable of bypassing structural barriers in the DNA or accommodating four DNA strands. The reaction exhibits the same limitations as that promoted by wild type RecA protein in the presence of adenosine 5'-O-(3-thio)triphosphate. The Mg2+ effects, the limitations of RecA-mediated DNA strand exchange in the absence of ATP hydrolysis, and unusual DNA structures observed by electron microscopy in some experiments, are interpreted in the context of a model in which a fast phase of DNA strand exchange produces a discontinuous three-stranded DNA pairing intermediate, followed by a slow phase in which the discontinuities are resolved. The mutant protein also facilitates the autocatalytic cleavage of the LexA repressor, but at a reduced rate.

Election spin resonance studies of free radical formation and oxygen consumption of lens epithelium during ultraviolet exposure

A long life election spin resonance (ESR) signal at g = 2.0006 was observed in the normal lens epithelium and cortical fibers. During ultraviolet (UV) exposure, a new ESR signal at g = 2.0060 was found in the lens epithelium. But this specific signal was not detected in the lens cortical fibers. This suggested that lens epithelial cells were more susceptible to the free radical formation which was induced by UV light. By means of ESR spin probe oximetry, the oxygen uptake of lens epithelial cells was measured. The more the oxygen uptake, the higher the K value was. The K value of the oxygen consumption of epithelial cell linearly correlated with time of consumption (20-60 min) and increased as a function of UV exposure time (1-5 min). The oxygen consumption rate of lens epithelial cell was approximately 1.38 x 10(6) and increased to 7.1 x 10(6) O2 molecules per cell per sec. The oxygen consumption rate increased more than 5 times. These results indicates that UV light can accelerate the respiratory function of lens epithelial cells. The necessity of excess oxygen of lens epithelial cells may play a role in the cataract formation induced by UV light.