Advancing chronic toxicity risk assessment in freshwater ecology by molecular characterization-based machine learning

The continuously increased production of various chemicals and their release into environments have raised potential negative effects on ecological health. However, traditional labor-intensive assessment methods cannot effectively and rapidly evaluate these hazards, especially for chronic risk. In this study, machine learning (ML) was employed to construct quantitative structure-activity relationship (QSAR) models, enabling the prediction of chronic toxicity to aquatic organisms by leveraging the molecular characteristics of pollutants, namely, the molecular descriptors, fingerprints, and graphs. The limited dataset size hindered the notable advantages of the graph attention network (GAT) model for the molecular graphs. Considering computational efficiency and performance (R2 = 0.78; RMSE = 0.77), XGBoost (XGB) was used for reliable QSAR-ML models predicting chronic toxicity using small- or medium-sized tabular data and the molecular descriptors. Further kernel density estimation analysis confirmed the high accuracy of the model for pollutant concentrations ranging from 10-3 to 102 mg/L, effectively aligning with most environmental scenarios. Model interpretation showed SlogP and exposure duration as the primary influential factors. SlogP, representing the distribution coefficient of a molecule between lipophilic and hydrophilic environments, had a negative effect on the toxicity outcomes. Additionally, the exposure duration played a crucial role in determining the chronic toxicity. Finally, the chronic toxicity data of bisphenol A validated the robustness and reliability of the model established in this research. Our study provided a robust and feasible methodology for chronic ecological risk evaluation of various types of pollutants and could facilitate and increase the use of ML applications in environmental fields.

Factors associated with acute care service use after epilepsy hospitalisation in people with intellectual disability

BACKGROUND

This study aimed to identify factors associated with unplanned acute hospital readmission and emergency department (ED) presentation after hospitalisation for epilepsy in people with intellectual disability (ID).

METHODS

This study is a retrospective cohort study using linked administrative datasets. We identified 3293 people with ID aged 5-64 years with a hospitalisation for epilepsy between 2005 and 2014 in New South Wales, Australia. We examined unplanned readmission and ED presentation within 30 or 365 days and associations with demographic, socio-economic and health status variables. Modified Poisson regression with robust estimation was used to model outcomes within 30 days. Negative binomial regression was used to account for the overdispersion of the data and to model 365-day outcome rates.

RESULTS

Around half of the cohort had an unplanned readmission and ED presentation within 365 days of the index hospitalisation. In fully adjusted models, being female, being a young adult and having a longer or acute care index admission, mental and physical comorbidities and a history of incarceration were associated with an elevated risk of readmission or ED presentation. The strongest association was observed between history of self-harm and 365-day readmission (incidence rate ratio 2.15, 95% confidence interval 1.41-3.29).

CONCLUSIONS

Socio-demographic, justice and health factors are associated with unplanned readmission and ED presentation risk after hospitalisation for epilepsy in people with ID. Interventions targeting improving continuity of care should be tailored for individuals and their support workers. The findings also emphasise the importance of person-centred multidisciplinary care across different health sectors.

[Homosexual behavior and related factors among married men who have sex with men in Mianyang city, Sichuan province]

Objective: To understand the homosexual behavior and related factors among married MSM in Mianyang city. Methods: Between January and October in 2017, a snowball sampling method was adopted to carry out cross-sectional survey through questionnaires plus HIV testing among those MSM in Mianyang city. Logistic regression model was used to analyze homosexual behaviors and related factors among married MSM under study. Statistical analysis was used by EpiData 3.1 and SPSS 19.0 software. Results: A total of 234 MSM participated in this survey. The overall rate of homosexual behavior in these married MSM appeared as 94.9% (222/234). Rate of having anal sex behavior was 94.4% (221/234) in the past 6 months, with rate of condom use as 57.9% (128/221). HIV positive rate was 8.1% (18/222). As for the motives for homosexual behavior after marriage, 87.8% (195/222) were driven by feelings of love, 12.2% (27/222) due to 'releasing pressure'. Proportion of male sex partners would include occasional sex partners (62.2%, 138/222), stable male sex partners (26.1%, 58/222) and stable boyfriends (11.7%, 26/222). Factors from logistic regression analysis showed that homosexual behaviors were related to the factors including education level of senior high school or above vs. education level of junior middle school or below (OR=3.65, 95%CI: 1.33-9.98); local residency over one year vs. the ones having local residency less than one year (OR=23.28, 95%CI:1.67-324.89); having 10 or more friends in the MSM community vs. having below 10 friends in MSM community (OR=4.15, 95%CI: 1.28-13.43); without sex pleasure with spouse vs. having sex pleasure with spouse (OR=3.25, 95%CI: 1.22-8.62); having 2 or more anal sex partners in the past 6 months vs. having less than 2 anal sex partners in the past 6 months (OR=0.28,95%CI: 0.09-0.81). Conclusions: The rate of homosexual behavior and HIV positive rate were high among MSM in Mianyang city. Homosexual behaviors after marriage were influenced by multiple factors among MSM. The motives of homosexual behavior after marriage were driven by feelings of love, the related factors were education level of senior high school or above, local residency over one year, having 10 or more friends in the MSM community and without sex pleasure with spouse. As for the motives of these behaviors was caused by releasing pressure, the related factors was having more than 2 anal sex partners.

Hepatitis B virus vaccine breakthrough infection: surveillance of S gene mutants of HBV

Hepatitis B (HB) is a worldwide public health problem, closely related with liver cirrhosis and hepatocellular carcinoma (HCC). The implementation of universal hepatitis B virus (HBV) vaccination programs has led to significant reduction in incidence of acute and chronic HB, liver cirrhosis and HCC. However, this success is now being threatened by the discovery of HBV vaccine breakthrough infection caused by the S gene mutants of HBV, high maternal viral load and virus-induced immunosuppression. An alteration in the antigenicity and immunogenicity of hepatitis B surface antigen (HBsAg) due to S gene mutations may compromise detection of HBsAg (diagnosis-escape mutants), treatment with hepatitis B-specific immunoglobulin (HBIG), and even cause infections in individuals who are antihepatitis B surface antigen (anti-HBs) antibody-positive after immunization (vaccine-escape mutants). By surveilling for S gene mutants of HBV among vaccinated population, we will have a better understanding of the mechanism of HBV vaccine breakthrough infection; potentially providing new ideas for designing better diagnostic assays and effective vaccines for prevention and treatment of HBV. This review attempts to briefly summarize the status and role of S gene mutations, B-cell epitopes and T-cell epitope mutants, and surveillance of mutant HBV variants in a hospital setting.

Dengue virus infections among blood donors in Guangxi of China, 2013-2014

BACKGROUND

An unexpected, large dengue outbreak, spreading to 20 cities of Guangdong province, occurred in July 2014. Considering the overwhelming influence of this seasonal epidemic, whether this dengue virus outbreak has an significant impact on the blood donors of the ajacent areas in Guangdong requires at least a preliminary investigation. Liuzhou City of Guangxi was chosen as a good representative of the neighbouring geographical location of the dengue virus (DENV) outbreak areas in this research. We therefore investigated qualified blood donations during potential dengue epidemic seasons and thus provided critical information for public health and donation policy making.

METHOD

A total of 1685 donations from 2013 to 2014 were collected at the Guangxi blood centre. Anti-DENV testing was performed using enzyme-linked immunosorbent assay (ELISA). Dengue IgG indirect ELISA and Dengue IgM capture ELISA were used to detect anti-DENV IgM and IgG. Repeat-reactive samples with ELISA test and 1685 donations with 421 pools were screened for dengue RNA by reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) using an in-house assay.

RESULTS

There was a total of 13 seropositive donors, including 6 IgM seropositive and 7 IgG seropositive. The total seropositive rate was 0·78%, with IgM 0·36% and IgG 0·42%. Seropositive donors were identified mostly between April and November, with a peak in November. .All samples in reactive pools and individual seropositive samples were negative in the follow-up RT-PCR test.

CONCLUSION

Our results suggested that the Guangdong dengue outbreak had limited impact on blood safety in surrounding areas under our current testing system.

Short-term supplementation of isocaloric meals with L-tryptophan affects pig growth

L-Tryptophan (Trp) and some of its metabolites regulate the circadian rhythm in mammals. We aimed to investigate the effects of short-term supplementation of Trp in isocaloric meals on growth performance using the parameters of multiple blood biomarkers and free amino acids in growing pigs. A total of 32 Landrace × Yorkshire barrows with a mean body weight of 8.64 (±1.13) kg were randomly assigned to four groups and then fed with various concentrations of Trp diets daily. Our results showed that sequential supplementation of different concentrations of Trp in isocaloric meals decreased the feed:gain (F:G) ratio (P = 0.079) and plasma urea and albumin (P = 0.019), whereas the level of total protein did not. Among the essential and conditionally essential amino acids, the concentrations of histidine, isoleucine, proline, threonine, arginine, and valine in the plasma decreased (P < 0.05), whereas the concentrations of Trp, glycine, serine, and methionine increased (P < 0.01). In addition, concentrations of branched chain amino acids also significantly decreased (P = 0.004), while the rate of conversion of Trp to branched chain amino acids increased (P < 0.001). Taken together, we show that administration of a high concentration of Trp in breakfast with decreasing concentrations of Trp in lunch and dinner positively affected feed utilization and improved feed efficiency, at least in part, through the optimization of amino acid interconversions and nitrogen utilization.

Association Between Interleukin-2 -330 T/G Polymorphism and Acute Renal Graft Rejection: A Meta-analysis

BACKGROUND

Interleukin-2 (IL-2) -330 T/G promoter polymorphism is involved in the acute rejection (AR) risk of kidney transplantation. However, results from published studies on the association between recipient IL-2-330 T/G polymorphism and AR risk are conflicting and inconclusive.

METHODS

We searched Medline, Embase, Web of Science, and Cochrane Central Register from their inceptions through January 2015 for relevant studies. Data concerning publication information, population characteristics, and transplant information were extracted. Odds ratios (ORs) were calculated for the association between IL-2-330 T/G polymorphism and AR risk.

RESULTS

This meta-analysis included 8 case-control studies with 1,405 cases of renal transplant recipients. The pooled estimate showed that IL-2-330 T/G polymorphism was not associated with AR risk: TT vs TG+GG: OR(fixed,) 0.93; 95% confidence interval [CI], 0.72-1.21; P = .60; GG vs TG+TT: OR(fixed), 1.15; 95% CI, 0.76-1.72; P = .51; TG vs TT+GG: OR(fixed), 1.01; 95% CI, 0.78-1.31; P = .91; T vs G: OR(fixed), 0.93; 95% CI, 0.77-1.13; P = .48. None of subgroup analyses yielded significant results in the association between IL-2-330 T/G polymorphism and AR risk. Meta-regression confirmed that there was no significant correlation between the preselected trial characteristics and our study results.

CONCLUSIONS

This meta-analysis suggests that IL-2-330 T/G polymorphism may not be associated with AR risk in renal transplant recipients.

Genetic Interactions Between TRPC6 and NPHS1 Variants Affect Posttransplant Risk of Recurrent Focal Segmental Glomerulosclerosis

Individuals with TRPC6 mutations have variable phenotypes, ranging from healthy carrier to focal segmental glomerulosclerosis (FSGS) leading to renal failure. Here, we describe a family where six members had a novel TRPC6 p.R68W (c.202C>T) mutation, two of whom had renal failure from FSGS, and one had proteinuria. One healthy carrier donated a kidney to her sister. Both donor and recipient had no proteinuria at 20 years posttransplant. Two synonymous NPHS1 polymorphisms, rs2285450 (c.294C>T) and rs437168 (c.2289C>T) segregated with renal failure in this family. These variants had higher allele frequencies in 97 unrelated patients with nephrotic syndrome or FSGS compared to 224 controls. Using patch-clamp experiments in HEK293 and podocytes, we showed that the p.R68W mutation increased TRPC6 current amplitudes, which may be explained by enhanced TRPC6 surface expression. Additionally, while wild-type nephrin suppressed TRPC6 currents, this ability was lost in the presence of NPHS1 c.294C>T polymorphism. When cells were transfected according to combined TRPC6 and NPHS1 genotypes in the family, those representing the donor had lower TRPC6 currents than cells representing the recipient, suggesting that interactions between TRPC6 and NPHS1 variants could possibly account for the variable penetrance of TRPC6 mutations and the absence of recurrence in the graft.

Resistance and integron characterization of Acinetobacter baumannii in a teaching hospital in Chongqing, China

A total of 189 Acinetobacter baumannii isolates were collected in 2011 from a teaching hospital in Chongqing, China. Susceptibility data showed strains carrying integrons were significantly more resistant to all tested antibiotics that strains lacking integrons. Five types of gene cassettes belonging to class I integrons were identified in this study, and for the first time two types of gene cassettes belonging to class II integrons are reported. Most of the cassettes belong to a class I integron (136/144) encoding arr3, aacA4, dfrA17, aadA5, aadB, cat, blaOXA10 , aadA1, aadA2, dfrA and aacC1. Isolates contained a class I gene cassette; AadA2-HP-dfrA was the prevalent strain in this hospital. A class II integron was detected in eight strains, which contained the type IV fimbriae expression regulatory gene pilR and sulfate adenylyltransferase, suggesting a possible role in multidrug resistance. The major epidemic strains from intensive care unit patients belong to international clone 2. In conclusion, the presence of integrons was significantly associated with multiple drug resistance of A. baumannii in this hospital, and class I integron isolates bearing AadA2-HP-dfrA were the prevalent strain in this hospital.

SCP1 regulates c-Myc stability and functions through dephosphorylating c-Myc Ser62

Serine 62 (Ser62) phosphorylation affects the c-Myc protein stability in cancer cells. However, the mechanism for dephosphorylating c-Myc is not well understood. In this study, we identified carboxyl-terminal domain RNA polymerase II polypeptide A small phosphatase 1 (SCP1) as a novel phosphatase specifically dephosphorylating c-Myc Ser62. Ectopically expressed SCP1 strongly dephosphorylated c-Myc Ser62, destabilized c-Myc protein and suppressed c-Myc transcriptional activity. Knockdown of SCP1 increased the c-Myc protein levels in liver cancer cells. SCP1 interacted with c-Myc both in vivo and in vitro. In addition, Ser245 at the C-terminus of SCP1 was essential for its phosphatase activity towards c-Myc. Functionally, SCP1 negatively regulated the cancer cell proliferation. Collectively, our findings indicate that SCP1 is a potential tumor suppressor for liver cancers through dephosphorylating c-Myc Ser62.

Ribosomal proteins L11 and L5 activate TAp73 by overcoming MDM2 inhibition

Over the past decade, a number of ribosomal proteins (RPs) have been found to have a role in activating the tumor suppressor p53 by directly binding to MDM2 and impeding its activity toward p53. Herein, we report that RPL5 and RPL11 can also enhance the transcriptional activity of a p53 homolog TAp73, but through a distinct mechanism. Interestingly, even though RPL5 and RPL11 were not shown to bind to p53, they were able to directly associate with the transactivation domain of TAp73 independently of MDM2 in response to RS. This association led to perturbation of the MDM2-TAp73 interaction, consequently preventing MDM2 from its association with TAp73 target gene promoters. Furthermore, ectopic expression of RPL5 or RPL11 markedly induced TAp73 transcriptional activity by antagonizing MDM2 suppression. Conversely, ablation of either of the RPs compromised TAp73 transcriptional activity, as evident by the reduction of p21 and Puma expression, in response to 5-fluorouracil (5-FU). Consistently, overexpression of RPL5 or RPL11 enhanced, but knockdown of either of them hampered, TAp73-mediated apoptosis. Intriguingly, simultaneous knockdown of TAp73 and either of the RPs was required for rescuing the 5-FU-triggered S-phase arrest of p53-null tumor cells. These results demonstrate a novel mechanism underlying the inhibition of tumor cell proliferation and growth by these two RPs via TAp73 activation.

Parameters from preoperative overnight oximetry predict postoperative adverse events

BACKGROUND

Continuous home monitoring of oxygen saturation has become a reliable and feasible practice. The objective of this study was to investigate the role of preoperative overnight oximetry in predicting postoperative adverse events.

METHODS

Following research ethics board approval, consented patients underwent a preoperative overnight monitoring of oxygen saturation with a portable oximeter. Parameters from the oximetry data were extracted and their predictive performance for postoperative adverse events was evaluated.

RESULTS

A total of 573 patients were studied with age: 60±12 years and 45% male. Oxygen desaturation index (ODI), cumulative time percentage with SpO2 <90% (CT90) and mean SpO2 were identified as significant predictors for postoperative adverse events. The privilege sensitivity, optimal predictive and privilege specificity cut-offs were: ODI: >3.0 events/h, >9.2 events/h and > 28.5 events/h; CT90: >0.1%, >1.1% and >7.2%; mean SpO2: <96.2%, <94.6% and <92.7%. The odds ratio for corresponding optimal cut-offs was: ODI 1.9 (95% CI: 1.4,2.7); CT90: 1.7 (95% CI: 1.2,2.4) and mean SpO2: 2.7 (95% CI: 1.9,3.8). The patients classified as high risk by ODI or CT90 or mean SpO2 had a significantly higher rate of postoperative adverse events. For ODI >28.5 vs. ODI ⋝28.5 events/h, the odds ratio adjusted with age, gender, body mass index and American Society of Anesthesiologists physical status was 2.2 (95% CI: 1.3-3.9).

CONCLUSION

Patients with mean preoperative overnight SpO2 <92.7% or ODI >28.5 events/h or CT90 >7.2% are at higher risk for postoperative adverse events. Overnight oximetry could be a useful tool to stratify patients for the risk of postoperative adverse events.

High STOP-Bang score indicates a high probability of obstructive sleep apnoea

Background

The STOP-Bang questionnaire is used to screen patients for obstructive sleep apnoea (OSA). We evaluated the association between STOP-Bang scores and the probability of OSA.

Methods

After Institutional Review Board approval, patients who visited the preoperative clinics for a scheduled inpatient surgery were approached for informed consent. Patients answered STOP questionnaire and underwent either laboratory or portable polysomnography (PSG). PSG recordings were scored manually. The BMI, age, neck circumference, and gender (Bang) were documented. Over 4 yr, 6369 patients were approached and 1312 (20.6%) consented. Of them, 930 completed PSG, and 746 patients with complete data on PSG and STOP-Bang questionnaire were included for data analysis.

Results

The median age of 746 patients was 60 yr, 49% males, BMI 30 kg m⁻², and neck circumference 39 cm. OSA was present in 68.4% with 29.9% mild, 20.5% moderate, and 18.0% severe OSA. For a STOP-Bang score of 5, the odds ratio (OR) for moderate/severe and severe OSA was 4.8 and 10.4, respectively. For STOP-Bang 6, the OR for moderate/severe and severe OSA was 6.3 and 11.6, respectively. For STOP-Bang 7 and 8, the OR for moderate/severe and severe OSA was 6.9 and 14.9, respectively. The predicted probabilities for moderate/severe OSA increased from 0.36 to 0.60 as the STOP-Bang score increased from 3 to 7 and 8.

Conclusions

In the surgical population, a STOP-Bang score of 5–8 identified patients with high probability of moderate/severe OSA. The STOP-Bang score can help the healthcare team to stratify patients for unrecognized OSA, practice perioperative precautions, or triage patients for diagnosis and treatment.

SELDI-TOF-MS-based serum proteomic screening in combination with CT scan distinguishes renal cell carcinoma from benign renal tumors and healthy persons

In order to identify the proteomic differences between renal cell carcinoma (RCC) and benign renal tumors, we analyzed 168 serum samples from 65 RCC patients, 34 patients with benign renal tumors, and 69 healthy persons using the IMAC-Cu2+ ProteinChip system by surface enhanced laser desorption/ionization mass spectrometry technology. Two decision trees were generated by Biomarker Pattern software to distinguish between RCC versus healthy and RCC versus patients with benign tumors, respectively. Although the sensitivity and specificity of the RCC vs. healthy decision tree were 97.6% and 95.7%, respectively, it could not be used to distinguish RCC from benign renal tumors. The sensitivity of a blind test process using RCC, benign tumors and healthy persons were 92%. The specificity of the test process was 35.3% for benign tumors and 95.5% for healthy persons. The sensitivity and specificity of the RCC-Benign tumors decision tree were 85.7% and 95.5%, respectively. The blind test process using RCC, benign tumors and healthy persons also showed significant results. The sensitivity was 90.0%. The specificity was 95.7% for healthy persons and 90.0% for benign tumors. Combining these data with the results of CT scanning, the sensitivity can be improved over the use of either CT and decision tree analysis and the specificity may reach 100%. Two peaks with molecular masses of 3887.11 Da and 11079.8 Da were detected that are potentially useful for the diagnosis or screening of RCC. It was found that these two peaks can be used, not only to distinguish the RCC vs. healthy cases, but also to distinguish RCC from benign renal tumors. In combination with CT scanning, the sensitivity and specificity of the diagnosis of renal tumors can be improved. However, the decision tree constructed for RCC and healthy persons may not present good specificity for use in distinguishing malignant from benign renal tumors.

Free amino acid and dipeptide changes in the body fluids from Alzheimer's disease subjects

Our aim was to determine changes in free amino acid (FAA) and dipeptide (DP) concentrations in probable Alzheimer's disease (pAD) subjects compared with control (CT) subjects using liquid chromatography and electrospray ionization tandem mass spectrometry (LCMS2). We recruited gender- and age-matched study participants based on neurological and neuropsychological assessments. We measured FAAs and DPs in cerebrospinal fluid (CSF), plasma and urine using LCMS2 with selected reaction monitoring (SRM). Imidazole-containing FAAs (histidine, methyl-histidine), catecholamines (L-DOPA and dopamine), citrulline, ornithine, glycine and antioxidant DPs (carnosine and anserine) accounted for the major changes between CT and pAD. Carnosine levels were significantly lower in pAD (328.4 +/- 91.31 nmol/dl) than in CT plasma (654.23 +/- 100.61 nmol/dl). In contrast, L-DOPA levels were higher in pAD (1400.84 +/- 253.68) than CT (513.10 +/- 121.61 nmol/dl) plasma. These data underscore the importance of FAA and DP metabolism in the pathogenesis of AD. Since our data show changes in antioxidants, neurotransmitters and their precursors, or FAA associated with urea metabolism in pAD compared with CT, we propose that manipulation of these metabolic pathways may be important in preventing AD progression.

Using a gene-switch transgenic approach to dissect distinct roles of MAP kinases in heart failure

We have demonstrated that Cre-loxP-mediated gene-switch transgenesis is an effective approach to achieve targeted and temporally regulated gene manipulation in the heart. Using this approach, we have established animal models with targeted activation of different MAPK pathways. From these animal models, we identified distinct features of cardiac pathology associated with individual MAPK branches (summarized in Fig. 8). Specifically, Ras activation appears to promote cardiac hypertrophy, whereas p38 and JNK activation does not. Whereas Ras activation leads to depressed diastolic function associated with suppressed calcium transients and SR calcium uptake, p38 activity seems to modulate cellular contractility without affecting intracellular calcium cycling. Although all three models displayed extensive remodeling in the myocardium, the extent and the composition of interstitial fibrosis are different among them, with Ras- and p38-activated hearts promoting collagen-based fibrosis, and JNK activation leading to induction in fibronectin-based reticular fiber. In addition, JNK activation leads to loss of Cx43 expression and abnormal cell-cell communication. Therefore, ERK, p38, and JNK are three distinct intracellular signaling pathways that contribute to different aspects of cardiac pathology during heart failure. Combining sophisticated genetic manipulation with comprehensive analysis at physiological, molecular, and genomic levels, the transgenic animals established in these studies should serve as valuable model systems to identify and dissect the underlying mechanisms for different aspects of cardiac pathology such as hypertrophy, contractile dysfunction, and abnormal cell-cell communication. The insights learned from these investigations may help to develop novel therapeutic approaches to confront this devastating disease.

The benefit-to-risk profile of melagatran is superior to that of hirudin in a rabbit arterial thrombosis prevention and bleeding model

Although hirudin is better than heparin at preventing recurrent ischemia in patients with unstable angina, hirudin produces more bleeding. The purpose of this study was to use a rabbit arterial thrombosis prevention and ear bleeding model to determine whether for equivalent efficacy, melagatran, a synthetic direct thrombin inhibitor, is safer than hirudin. A combination of balloon injury and stasis was used to induce thrombosis in the distal aorta, and patency and blood flow were continuously monitored with ultrasonic flow probes. Rabbits were randomized to melagatran (in total doses of 78-313 nmol kg(-1)), hirudin (in total doses of 18-107 nmol kg(-1)), or saline over 90 min. To assess safety, blood loss from standardized ear incisions was measured. Both melagatran and hirudin produced dose-dependent increases in patency and blood flow. At doses that maintained the highest levels of patency, however, melagatran produced 2-3-fold less bleeding than hirudin. Thus, at maximally effective doses, melagatran causes less bleeding than hirudin in this model. These findings raise the possibility that some direct thrombin inhibitors are safer than others.

The in vivo role of p38 MAP kinases in cardiac remodeling and restrictive cardiomyopathy

Stress-induced mitogen-activated protein kinase (MAP) p38 is activated in various forms of heart failure, yet its effects on the intact heart remain to be established. Targeted activation of p38 MAP kinase in ventricular myocytes was achieved in vivo by using a gene-switch transgenic strategy with activated mutants of upstream kinases MKK3bE and MKK6bE. Transgene expression resulted in significant induction of p38 kinase activity and premature death at 7-9 weeks. Both groups of transgenic hearts exhibited marked interstitial fibrosis and expression of fetal marker genes characteristic of cardiac failure, but no significant hypertrophy at the organ level. Echocardiographic and pressure-volume analyses revealed a similar extent of systolic contractile depression and restrictive diastolic abnormalities related to markedly increased passive chamber stiffness. However, MKK3bE-expressing hearts had increased end-systolic chamber volumes and a thinned ventricular wall, associated with heterogeneous myocyte atrophy, whereas MKK6bE hearts had reduced end-diastolic ventricular cavity size, a modest increase in myocyte size, and no significant myocyte atrophy. These data provide in vivo evidence for a negative inotropic and restrictive diastolic effect from p38 MAP kinase activation in ventricular myocytes and reveal specific roles of p38 pathway in the development of ventricular end-systolic remodeling.

[Analysis of bacterial resistance to antibiotics in a burn ward]

OBJECTIVE

To analyze the bacterial resistance to antibiotics in a burn ward in the past 4 years.

METHODS

Six hundred and fifty strains of bacteria were isolated from the wounds and blood of burn patients admitted to our hospital in recent 4 years. Slip agar diffusion method was employed to carry out antibiotic sensitivity test, and the results were interpreted according to the NCCLS criteria. Extended spectrum beta -- lactamases (ESBLs) were detected by double slips synergic test in 45 strains of Klebsiella Pneumoniae.

RESULTS

Only vancomycin was effective for staphylococcus aureus, and Imipenem was effective for E. coli, E. cloacae and K. pneumoniae. But P. aeruginosa was only susceptible to polymyxin -- B. In addition, Thirty -- eight out of 45 strains of K. pneumoniae were ESBLs positive with the incidence of 84.4%.

CONCLUSION

The high resistance of the bacteria to most antibiotics in our burn ward might be related to the high production of beta -- lactamases and especially ESBLs. Imipenem remained stable to ESBLs and remained highly effective for most bacteria. But antibiotics with beta -- lactamases inhibitor became less effective in recent years. The resistance rate of P. aeruginosa to Imipenem increased gradually in recent years. This might be due to the abuse of Tienam in burn patients, which stimulated the bacteria to produce a new metallic beta -- lactamases transfected by plasmid, decreasing the production of bacterial outer membrane proteins and inducing a change in membranous permeability.

A novel approach to arterial thrombolysis

Achieving early, complete, and sustained reperfusion after acute myocardial infarction does not occur in approximately 50% of patients, even with the most potent established thrombolytic therapy. Bleeding is observed with increased concentrations of thrombolytics as well as with adjunctive antithrombotic and antiplatelet agents. A novel approach to enhance thrombolytic therapy is to inhibit the activated form of thrombin-activatable fibrinolysis inhibitor (TAFI), which attenuates fibrinolysis in clots formed from human plasma. Identification of TAFI in rabbit plasma facilitated the development of a rabbit arterial thrombolysis model to compare the thrombolytic efficacy of tissue-plasminogen activator (tPA) alone or with an inhibitor, isolated from the potato tuber (PTI), of activated TAFI (TAFIa). Efficacy was assessed by determining the time to patency, the time the vessel remained patent, the maximal blood flow achieved during therapy, the percentage of the original thrombus, which lysed, the percentage change in clot weight, the net clot accreted, and the release of radioactive fibrin degradation products into the circulation. The results indicate that coadministration of PTI and tPA significantly improved tPA-induced thrombolysis without adversely affecting blood pressure, activated partial thromboplastin time, thrombin clotting time, fibrinogen, or alpha-2-antiplasmin concentrations. The data indicate that inhibitors of TAFIa may comprise novel and very effective adjuncts to tPA and improve thrombolytic therapy to achieve both clot lysis and vessel patency.

Potential thermal artifacts in hip joint wear simulators

Frictional heat was monitored during wear tests of ultrahigh molecular weight polyethylene acetabular cups bearing against femoral balls of metal or ceramic in a hip simulator, using bovine serum as a lubricant. About 1 to 2 h of continuous cycling were required for the temperature in the zone of contact between the cup and ball to rise to its maximum steady value, and this equilibrium temperature was markedly higher with increased load and/or cycling rate. Frictional heating caused substantial precipitation of the proteins from the serum and, in some of the tests running at 1.5 or 2 Hz, an adherent proteinaceous layer was observed attached to the surface of the balls. The maximum temperature was also substantially higher in tests run with the cup mounted above the ball rather than below. Surprisingly, the tests running at higher frictional torque and temperature (i.e., those with the most protein precipitation and/or adherent layers) produced the least wear of the polyethylene. This might have been due to the solid proteins that formed a protective layer between the ball and cup. Because patients with hip prostheses typically do not walk for hours without rest, the maximum temperatures in vivo are likely to be much lower than those reached in the hip simulator. Therefore, the affects of protein precipitation on the resultant wear properties of the materials should be considered potential artifacts of the hip simulator tests. Increasing the volume of the lubricant bath reduced the maximum temperatures for tests running at 1.5 Hz but had little affect at 2 Hz. Reducing the cycling rate is an effective way to avoid overheating of the specimens, but this necessarily extends the time required to complete a test.

[Monitoring of bacteria resistance in burn patients]

OBJECTIVE

To monitor the bacteria resistance in burn patients.

METHODS

Disk susceptibility tests were performed and interpreted according to the NCCLS criteria. Four kinds of the third generation cephalosporins extended-spectrum beta-lactamase produced by multi-resistant of P. aeruginosa and K. Pneumoniae strains were detected after 20 microgram of sulbactam was added respectively, in contrast to no sulbactam.

RESULTS

227 strains were isolated from burn patients. 195 strains (86%) were gram-negative bacteria. Disk susceptibility showed various bacteria had high antibiotic resistance and multi-resistant rate. S. aureus was only susceptible to vancomycin, its resistant rate to imipenem was 19%. P. aeruginosa was only susceptible to polymyxin-B, its resistant rate to ceftazidime was 20%. However, after stop using ceftazidime two years, the susceptibility to gram-negative bacteria recovered. The resistant rate of ceftazidime to P. aeruginosa, E. coli, K. pneumoniae were decreased respectively. The resistance to quinolones was increased. The resistant rate of ciprofloxacin to P. aeruginosa, K. pneumoniae was increased respectively. After 20 microgram sulbactam added to cephalosporins drug disks, the primary susceptibility of ceftazidime to P. aeruginosa and K. pneumoniae recovered, and the antibiotic was better than the other cephalosporins.

CONCLUSIONS

It is important to monitor the bacteriology in burn patients at all time, and understand the changing pattern of bacterial flora, antibiotic susceptibility and bacterial strains spreading in burn ward. Extended-spectrum beta-lactamases is the cause of resistance. After sulbactam added to the third generation of cephalosporins, the beta-lactamases were inhibited, and the susceptibility of antibiotics to bacteria were increased and ceftazidime was prior to others.

Hirudin causes more bleeding than heparin in a rabbit ear bleeding model

This study was undertaken to determine the appropriateness of the current practice of using the activated partial thromboplastin time (APTT) to select hirudin doses. A rabbit bleeding ear model was used to compare the effects of various doses of heparin and hirudin on the relationship between the APTT and bleeding. In addition, the effects of these agents on the thrombin clotting time (TCT) and factor Xa clotting time also were examined. Both heparin and hirudin produced a concentration-dependent increase in bleeding. When bleeding was plotted as a function of APTT ratio, even a small increase in APTT ratio within the therapeutic range of 1.5 to 2.5 resulted in a marked increase in bleeding with hirudin but not with heparin. The TCT was more responsive than the APTT or factor Xa clotting time to increases in hirudin-induced bleeding. In this model, hirudin produces more bleeding than heparin when the agents are used in doses that increase the APTT ratio to the same extent. These studies highlight the pitfalls of extrapolating from experience with heparin when choosing a test to monitor new antithrombotics. Our findings also suggest that the TCT may be more responsive than the APTT for monitoring hirudin therapy.

alpha-Substituted malonester amides: tools to define the relationship between ACAT inhibition and adrenal toxicity

We prepared a series of alpha-substituted malonester amides that were evaluated for their ability to inhibit acyl-CoA:cholesterol O-acyl transferase activity in vitro and to lower plasma total cholesterol levels in a variety of cholesterol-fed animal models. Compounds of this series were also useful in examining the relationship between adrenal toxicity and ACAT inhibition. One compound from this series, 9f, was a potent inhibitor of ACAT in both the microsomal and cellular assays. It was also bioavailable as determined by both a bioassay and a HPLC-UV assay. This compound was evaluated in both guinea pig and dog models of adrenal toxicity and compared to tetrazole amide 15. In the most sensitive species, the dog, both of these compounds achieved good plasma levels; however, compound 9f caused adrenal necrosis, whereas compound 15 had no effect on the adrenal gland. This adds to the growing body of evidence that the adrenal toxicity observed with ACAT inhibitors may not be mechanism related.

Interaction of low molecular weight heparin with ketorolac

Postoperative patients may receive ketorolac, a nonsteroidal antiinflammatory drug that inhibits platelet function, for analgesia and may receive low-molecular-weight heparin (LMWH) for thrombosis prevention. We investigated whether the combination of these two agents increases blood loss in a rabbit model of hemostasis. In a randomized, blinded study, animals received either intramuscular ketorolac (0.5 mg/kg or 1.0 mg/kg) and subcutaneous saline solution, subcutaneous LMWH (100 U/kg) and intramuscular saline solution, ketorolac (0.5 mg/kg or 1.0 mg/kg) and subcutaneous LMWH (100 U/kg), or intramuscular and subcutaneous saline solution given 30 minutes before ear incision and measurement of blood loss. Collagen-induced platelet aggregation was examined and anti-Xa levels were determined by using a chromogenic substrate method. As compared with results in saline-treated controls, blood loss was significantly increased in animals receiving ketorolac in a dose of 1.0 mg/kg but not in those treated with 0.5 mg/kg. The addition of LMWH did not further increase blood loss above that observed with either dose of ketorolac alone. Platelet aggregation was inhibited by both doses of ketorolac. The anti-Xa levels in the LMWH-treated animals were comparable to those measured in patients receiving these agents for prophylaxis (0.09 to 0.13 U/ml). We conclude that in the rabbit model, LMWH does not augment ketorolac-associated bleeding when both agents are used in doses comparable to those given to human patients.

The regulation of plasminogen activators and plasminogen activator inhibitor type 1 in endothelial cells by sex hormones

OBJECTIVE

The purpose of this study was to assess the effect of 17 beta-estradiol, progesterone, and testosterone on secretion of plasminogen activators and plasminogen activator inhibitor type 1 by cultured endothelial cells.

STUDY DESIGN

Bovine aortic endothelial cells were cultured in medium that contained 17 beta-estradiol, progesterone, or testosterone at various concentrations (10(-13) to 10(-6) mol/L). Plasminogen activator activity in culture medium in the presence of cells was assayed after a 36-hour incubation using chromogenic substrate and iodine 125-labeled fibrin plate assays. Plasminogen activator inhibitor type 1 antigen was detected in conditioned media of bovine aortic endothelial cells by Western blotting analysis.

RESULTS

All three steroid hormones exhibited biphasic dose-response effects, characterized by stimulation of plasminogen activator secretion at lower concentrations and inhibition of plasminogen activator secretion at higher concentrations. A significant stimulatory effect on plasminogen activator secretion (74% over control) was observed at a 17 beta-estradiol concentration of 10(-12) mol/L (p < 0.03). At higher concentrations of 17 beta-estradiol, progesterone, and testosterone, inhibition of plasminogen activator secretion was observed (p < 0.05). Decreased levels of plasminogen activator inhibitor type 1 antigen were detected in supernatants treated with either 17 beta-estradiol or progesterone at a concentration of 10(-12) mol/L and were maximal at 10(-7) mol/L 17 beta-estradiol, progesterone, and testosterone.

CONCLUSION

The secretion of plasminogen activators and plasminogen activator inhibitor type 1 is regulated in a biphasic dose-dependent manner by sex hormones in bovine aortic endothelial cells.

Prevention of thrombus formation and growth by antithrombin III and heparin cofactor II-dependent thrombin inhibitors: importance of heparin cofactor II

Heparin (HEP) prevents thrombus formation (TF) and thrombus growth (TG), by accelerating thrombin (THR) inhibition by antithrombin III (ATIII). Recent studies suggest that dermatan sulphate which catalyzes thrombin inhibition by heparin cofactor II (HCII), can inhibit TF and TG as effectively as HEP. This study compared the antithrombotic effects of HEP and another agent, Sulodexide (SLX) which catalyzes thrombin inhibition by ATIII and HCII simultaneously. TF was induced in rabbit jugular veins, using the stasis/hypercoagulation model. TG was measured as the accretion of 125I-fibrin onto existing thrombi in rabbit jugular veins. HEP and SLX inhibited TF when given in doses of 10 and 5 anti-thrombin U/kg, respectively. SLX (16 anti-thrombin U/kg or 260 micrograms/kg) was more effective than HEP (120 anti-thrombin U/kg or 800 micrograms/kg) in preventing TG when administered either as a bolus or by continuous infusion. These data suggest that agents which accelerate THR inhibition by both ATIII and HCII simultaneously, can inhibit TF and TG with less systemic anticoagulation than comparable antithrombotic doses of HEP.

Recombinant alpha-interferon inhibits colony formation of bone marrow fibroblast progenitor cells (CFU-F)

Alpha-Interferon (IFN-alpha) has been shown to inhibit colony formation of hematopoietic progenitor cells, including colony-forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM), day 7 colony-forming unit granulocyte-macrophage (CFU-GM), day 14 CFU-GM, burst-forming unit erythroid (BFU-E), pluripotent stem cells (CFU-S), and colony-forming unit megakaryocyte (CFU-MK). The present study was designed to see whether IFN-alpha also has inhibitory effects on bone marrow fibroblast progenitors (CFU-F). We found that IFN-alpha exerted a significant inhibitory effect on both rabbit and human CFU-F formation. Inhibition of human marrow CFU-F formation by alpha interferon was unaffected by removal of 98% of monocytes/macrophages and T lymphocytes from light density marrow cells. This finding suggests that IFN-alpha probably exerts a direct inhibitory effects.

Evaluation of corrected loss variance as a visual field index. II. Corrected loss variance in conjunction with mean defect may identify stages of glaucoma

Although corrected loss variance (CLV) may enhance the sensitivity of field examinations in the early stages of glaucoma, the value of CLV has not been investigated with advancing glaucoma. In this study we report mean defect (MD) and CLV for 266 Octopus field examinations (a total of 57 eyes and 47 patients with open-angle glaucoma) collected over a period of approximately 6 years on a stored database system. We find that CLV is generally elevated (relative to the normal controls) independent of MD. However, the elevated level of CLV does not vary with increasing field loss as indicated by MD. A classification system for defining stages of glaucoma is proposed utilizing CLV and MD as a combined index.