A metaphyseal fracture rat model for mechanistic studies of osteoporotic bone healing.

Most osteoporotic fractures occur at metaphyseal regions of long bones. The present study proposed a clinically relevant animal model that satisfied: i) induction of osteoporosis, ii) unilateral complete osteotomy at metaphysis, iii) internal fixation. 6 months old female Sprague-Dawley rats (n = 64) were randomly divided into the ovariectomised-metaphyseal osteotomy (OVX, n = 32) and metaphyseal osteotomy (SHAM, n = 32) groups. The metaphyseal-osteotomy model was created with a plate-fixation of the osteotomy and assessed by X-ray, micro-computed tomography, histomorphometry and mechanical testing at weeks 1, 3 and 6. X-ray results showed complete healing of metaphyseal osteotomy at week 6. Histology showed 3 stages of metaphyseal healing. Stage 1 was characterised by fibrous tissue, consisting of disorganised orientation of collagen fibres, and infiltration of immune cells. At stage 2, a transitional zone consisting of maturing fibrous tissue and differentiating mesenchymal cells with early trabecular bone formation and disorganised woven bone were observed. During stage 3, cortical bone ends unified and woven bone underwent transformation to lamellar bone. OVX group healing was significantly delayed when compared to SHAM samples. The study demonstrated that healing of osteoporotic osteotomy at the metaphyseal region was delayed in terms of radiography, histomorphometry and mechanical strength. These quantitative evaluations, along with histological features, may provide key references for future studies. The animal model may provide additional clinical relevance as most osteoporotic fracture in humans occurs at metaphyseal regions.

Candida catenulata Candidaemia and Possible Endocarditis in a Cirrhotic Patient Successfully De-escalated to Oral Fluconazole.

WHAT IS KNOWN AND OBJECTIVE: Candida catenulata is a fungus commonly found in Australian cheeses. C. catenulata has been identified as the causative pathogen for one report of onychomycosis and one report of candidaemia. CASE DESCRIPTION: A 37-year-old male underwent surgery for an incarcerated umbilical hernia repair and bowel obstruction and presented with severe abdominal pain and ascitic fluid draining from the surgical site. C. catenulata was isolated in blood cultures. The patient was treated with antifungal therapy for approximately 6 weeks. WHAT IS NEW AND CONCLUSION: To our knowledge, this is the first case describing successful treatment of possible fungal endocarditis caused by C. catenulata.

A systematic review of current osteoporotic metaphyseal fracture animal models.

OBJECTIVES: The treatment of osteoporotic fractures is a major challenge, and the enhancement of healing is critical as a major goal in modern fracture management. Most osteoporotic fractures occur at the metaphyseal bone region but few models exist and the healing is still poorly understood. A systematic review was conducted to identify and analyse the appropriateness of current osteoporotic metaphyseal fracture animal models. MATERIALS AND METHODS: A literature search was performed on the Pubmed, Embase, and Web of Science databases, and relevant articles were selected. A total of 19 studies were included. Information on the animal, induction of osteoporosis, fracture technique, site and fixation, healing results, and utility of the model were extracted. RESULTS: Fracture techniques included drill hole defects (3 of 19), bone defects (3 of 19), partial osteotomy (1 of 19), and complete osteotomies (12 of 19). Drill hole models and incomplete osteotomy models are easy to perform and allow the study of therapeutic agents but do not represent the usual clinical setting. Additionally, biomaterials can be filled into drill hole defects for analysis. Complete osteotomy models are most commonly used and are best suited for the investigation of therapeutic drugs or noninvasive interventions. The metaphyseal defect models allow the study of biomaterials, which are associated with complex and comminuted osteoporotic fractures. CONCLUSION: For a clinically relevant model, we propose that an animal model should satisfy the following criteria to study osteoporotic fracture healing: 1) induction of osteoporosis, 2) complete osteotomy or defect at the metaphysis unilaterally, and 3) internal fixation.Cite this article: R. M. Y. Wong, M. H. V. Choy, M. C. M. Li, K-S. Leung, S. K-H. Chow, W-H. Cheung, J. C. Y. Cheng. A systematic review of current osteoporotic metaphyseal fracture animal models. Bone Joint Res 2018;7:6-11. DOI: 10.1302/2046-3758.71.BJR-2016-0334.R2.

Attitudes, barriers and facilitators to the conduct of research in government hospitals: a cross-sectional study among specialists in government hospitals, northern states of Malaysia.

INTRODUCTION: Specialists constitute a major 'driving force' and catalyst for growth of research in their speciality. A clearer understanding is required as to what motivates their participation in research as well as the barriers they faced. This research aims to study the attitudes, barriers and facilitators faced by specialists and to identify strategies to promote and sustain research activities in their hospitals. METHODOLOGY: A cross-sectional survey using selfadministered questionnaires was conducted among all specialists working in government specialist hospitals in the northern states of Malaysia. RESULTS: Out of 733 questionnaires distributed, 467 were returned giving a response rate of 63.7%. Ninety-nine percent of the respondents believed that research benefits patients while 93.3% think research helps in their professional development. However, 34.8% think that under their present working conditions, it is unlikely they will participate in research. The major barriers identified were lack of funds for research (81%); lack access to expertise, software or statistical analysis (78.4%); interference with daily work schedule (75.1%) and inconsistent manpower in their department (74.2%). There are three barriers with statistically significant difference between hospitals with CRC compared to hospitals without CRC; lack of funds, mentors and access to expertise, software or statistical analysis. The demographic factors, attitudes and barriers contributing to involvement in research also investigated. The main facilitators for the conduct of research are potential to benefit patients and potential for professional development. CONCLUSION: Taking note of the findings, the Ministry of Health can implement appropriate strategies to improve specialist participation in research.

Paraquat poisoning: experience in hospital taiping (year 2008 - october 2011).

INTRODUCTION: Paraquat is a quaternary nitrogen herbicide which is highly toxic to human. Death is usually from respiratory failure and may occur within days up to a month after exposure. It is easily available and commonly abused to commit suicide. METHODOLOGY: This is a retrospective study describing the demographic characteristics, clinical features and outcomes of paraquat poisoning cases admitted to Hospital Taiping from 1st January 2008 to 30th October 2011. Medical records of 79 patients were reviewed. RESULT: Majority were of the Indian ethnicity (72.2%) followed by Chinese (13.9%) and Malay (10.1%). Majority was male (73.4%) and between 20 to 29 years old (34.2%). The median age of the patients was 30 years old. The mean length of stay was 6.2 days. Most exposures were intentional (69.6%) and presented to the hospital early at less than 6 hours after exposure (72.2%). Patients with positive urine paraquat result had significantly higher mortality rate compared to patients with negative results (47.4% vs 15.2% respectively). We found that neither hemofiltration nor immunosuppressive therapies help to improve survival. CONCLUSION: The non-survivor characteristics of patients with paraquat poisoning are intentional exposure, delay from exposure to hospital admission, urine paraquat positivity and manifestation of respiratory failure. The demographic characteristics, reasons for exposure and mortality rate are similar to previous reports. Urine paraquat may be used to assess severity of the exposure as well as prognosis. Hemofiltration and immunosuppression therapy do not improve patients' survival and paraquat remains a lethal killer.

Histone deacetylase inhibitor induces DNA damage, which normal but not transformed cells can repair.

Histone deacetylase inhibitors (HDACi) developed as anti-cancer agents have a high degree of selectivity for killing cancer cells. HDACi induce acetylation of histones and nonhistone proteins, which affect gene expression, cell cycle progression, cell migration, and cell death. The mechanism of the tumor selective action of HDACi is unclear. Here, we show that the HDACi, vorinostat (Suberoylanilide hydroxamic acid, SAHA), induces DNA double-strand breaks (DSBs) in normal (HFS) and cancer (LNCaP, A549) cells. Normal cells in contrast to cancer cells repair the DSBs despite continued culture with vorinostat. In transformed cells, phosphorylated H2AX (gammaH2AX), a marker of DNA DSBs, levels increased with continued culture with vorinostat, whereas in normal cells, this marker decreased with time. Vorinostat induced the accumulation of acetylated histones within 30 min, which could alter chromatin structure-exposing DNA to damage. After a 24-h culture of cells with vorinostat, and reculture without the HDACi, gammaH2AX was undetectable by 2 h in normal cells, while persisting in transformed cells for the duration of culture. Further, we found that vorinostat suppressed DNA DSB repair proteins, e.g., RAD50, MRE11, in cancer but not normal cells. Thus, the HDACi, vorinostat, induces DNA damage which normal but not cancer cells can repair. This DNA damage is associated with cancer cell death. These findings can explain, in part, the selectivity of vorinostat in causing cancer cell death at concentrations that cause little or no normal cell death.

Cerebral blood flow changes during pilocarpine-induced status epilepticus activity in the rat hippocampus.

INTRODUCTION: There is a known relationship between convulsive status epilepticus (SE) and hippocampal injury. Although the precise causes of this hippocampal vulnerability remains uncertain, potential mechanisms include excitotoxicity and ischaemia. It has been hypothesised that during the early phase of seizures, cerebral blood flow (CBF) increases in the cortex to meet energy demand, but it is unclear whether these compensatory mechanisms occur in the hippocampus. In this study we investigated CBF changes using perfusion MRI during SE in the pilocarpine rat. METHODS: First, we determined whether SE could be induced under anaesthesia. Two anaesthetic protocols were investigated: isoflurane (n=6) and fentanyl/medetomidine (n=7). Intrahippocampal EEG electrodes were used to determine seizure activity and reflex behaviours were used to assess anaesthesia. Pilocarpine was administered to induce status epilepticus. For CBF measurements, MRI arterial spin labelling was performed continuously for up to 3h. Either pilocarpine (375 mg/kg) (n=7) for induction of SE or saline (n=6) was administered. Diazepam (10mg/kg) was administered i.p. 90 min after the onset of SE. RESULTS AND DISCUSSION: We demonstrated time-dependent significant (p<0.05) differences between the CBF responses in the parietal cortex and the hippocampus during SE. This regional response indicates a preferential distribution of flow to certain regions of the brain and may contribute to the selective vulnerability observed in the hippocampus in humans.

Estimating disease prevalence using census data.

We describe a method of working on publicly available data to estimate disease prevalence in small geographic areas using Helicobacter pylori as a model infection. Using data from the Third National Health and Nutrition Examination Survey, risk parameters for H. pylori infection were obtained by logistic regression and validated by predicting 737.5 infections in an independent cohort with 736 observed infections. The prevalence of H. pylori infection in the San Francisco Bay Area was estimated with the probabilities obtained from a predictive logistic model, using risk parameters with individual-level 1990 U.S. Census data as input. Predicted H. pylori prevalence was also compared to gastric cancer incidence obtained from the Northern California Cancer Center and showed a positive correlation with gastric cancer incidence (P<0.001, R2=0.87), and no statistically significant association with other malignancies. By exclusively using publicly available data, these methods may be applied to selected conditions with strong demographic predictors.

The distribution of major histocompatibility complex class I polymorphic Alu insertions and their associations with HLA alleles in a Chinese population from Malaysia.

The frequency and association of polymorphic Alu insertions (POALINs) with human leucocyte antigen (HLA) class I genes within the class I genomic region of the major histocompatibility complex (MHC) have been reported previously for three populations: the Australian Caucasian, Japanese and north-eastern Thai populations. Here, we report on the individual insertion frequency of the five POALINs within the MHC class I region, their HLA-A and HLA-B associations, the POALIN haplotype frequencies and the HLA-A/POALIN four-loci haplotype frequencies in the Malaysian Chinese population. The phylogenetic relationship of the four populations based on the five POALIN allele frequencies was also examined. In the Malaysian Chinese population, the POALIN AluyHG was present at the highest frequency (0.560), followed by AluyHJ (0.300), AluyMICB (0.170), AluyTF (0.040) and AluyHF (0.030). The most frequent five-loci POALIN haplotype of the 16 inferred haplotypes was the AluyHG single insertion haplotype at a frequency of 0.489. Strong associations were present between AluyHJ and HLA-A24, HLA-A33 and HLA-A11 and between AluyHG and HLA-A2, HLA-A24 and HLA-A11, and these were reflected by the inferred haplotype frequencies constructed from the combination of the HLA-A locus and the AluyHG, AluyHJ and AluyHF loci. The strongest association of AluyMICB was with the HLA-B54 allele (five of five), whereas the associations with the other 17 HLA-B alleles were weak, moderate or undetermined. Phylogenetic analysis of the five POALIN allele frequencies places the Malaysian Chinese closest to the Japanese and north-eastern Thai populations in the same cluster and separate to the Australian Caucasian population. The MHC POALINs are confirmed in this study to be informative genetic markers in lineage (haplotype) analysis, population genetics and evolutionary relationships, especially in studying the MHC genomic region.

Pneumothorax in association with spontaneous ventilation general anaesthesia--an unusual cause of hypoxaemia.

A 43-year-old ASA PS II male patient developed a pneumothorax while breathing pontaneously through a supraglottic airway device during a general anaesthetic. Unexplained hypoxaemia occurred after an episode of coughing. Clinical examination appeared to be normal apart from the persistent oxygen desaturation. A pneumothorax was diagnosed in the post anaesthesia care unit by chest X-ray. The pneumothorax responded to conventional management and the patient made an uneventful recovery. We recommend a high index of suspicion in any patient who coughs and later has unexplained hypoxaemia during general anaesthesia, even if a supraglottic airway device has been inserted.

Lactacystin-induced apoptosis of cultured mouse cortical neurons is associated with accumulation of PTEN in the detergent-resistant membrane fraction.

The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate [PtdIns(3,4,5)P3]. Implicit in this notion is that PTEN needs to be targeted to the plasma membrane to dephosphorylate PtdIns(3,4,5)P3. However, the recruitment of PTEN to the plasma membrane is not fully understood. Here, we demonstrate PTEN accumulation in the detergent-insoluble fraction of neuronal cells in response to treatment by the proteasome inhibitor lactacystin. First, lactacystin induces apoptosis and the activation of caspase-3 in cultured cortical neurons. Second, PTEN undergoes proteolysis to form a truncated 50-kDa form that lacks parts of its C-terminal tail. Third, the truncated PTEN is stably associated with the detergent-insoluble fraction in which the plasma membrane marker protein flotillin-1 resides. Taken together, our results suggest that truncation and accumulation of PTEN to the detergent-insoluble membrane fraction are two events associated with the apoptotic signals of the proteasome inhibitor in cortical neurons.

Test characteristics of a level I or II fetal ultrasound in detecting structural heart disease.

At the University of California Davis Medical Center, a screening fetal ultrasound examination (level I or II) incorporates a comprehensive segmental evaluation of the fetal heart. This study evaluated the reliability of the fetal ultrasound exam in the detection of abnormal heart anatomy. Our retrospective study reviewed results of 614 antenatal patients that had a screening fetal ultrasound exam. All patients subsequently underwent a detailed targeted fetal cardiac ultrasound exam performed by a pediatric cardiac sonographer and reviewed by a board-certified pediatric cardiologist. Of these 614 patients, 60 fetuses had structural heart disease by the targeted fetal exam. The screening fetal ultrasound exam correctly identified 55 of the 60, with 5 false negatives (8.3% false-negative rate) and 1 false positive (1.7% false-positive rate). Our study suggests that if a screening fetal ultrasound exam incorporates a segmental evaluation of the fetal heart it can reliably detect abnormal heart anatomy. At our institution a targeted fetal cardiac exam is now used to confirm and provide detailed assessment of the heart anatomy when a screening fetal exam is positive for heart disease.

Ethanol inhibits spontaneous activity of central nucleus of the amygdala neurons but does not impair retention in the passive-avoidance task.

BACKGROUND: Behavioral studies using pharmacological manipulations that increase neuronal activity of the central nucleus of the amygdala (CeA) have implicated the CeA in enhancement of memory modulation. To date, however, there has been a dearth of studies investigating the effect of a drug that decreases CeA activity on memory modulation-a drug that inhibits the neuronal activity of the CeA might be expected to impair memory modulation. To determine whether ethanol inhibits CeA activity and, if so, whether decreased CeA activity is associated with impairment of memory modulation, this study investigated the effect of ethanol on spontaneous single-unit activity of CeA neurons and retention in the passive-avoidance task. METHODS: The effect of ethanol (0.35, 0.75, 1.5, 2.5 g/kg) was determined on spontaneously firing neurons in the CeA in urethane-anesthetized rats by use of standard in vivo single-unit electrophysiological recording techniques. Additionally, the effect of ethanol when administered immediately after training in a standard passive-avoidance task was determined on retention the following day. RESULTS: Ethanol profoundly inhibited spontaneous CeA firing rates in urethane-anesthetized rats at all doses tested. Maximal inhibition was related to dose. Each dose of ethanol significantly inhibited CeA activity within 15 min of administration; within 35 min of administration, 0.75 g/kg of ethanol inhibited CeA activity by 65.2%, and the highest dose (2.5 g/kg) produced nearly complete suppression of CeA activity (81.3%). Although ethanol markedly inhibited CeA activity, these same doses of ethanol failed to impair retention in the passive-avoidance task: 0.35, 0.75, 1.5, and 2.5 g/kg of ethanol, administered immediately after training, failed to alter latency to step-through the following day. CONCLUSIONS: These results show that ethanol profoundly inhibits spontaneous CeA activity and suggest that inhibition of the CeA is not sufficient to impair retention in the passive-avoidance task.

Structural organization of the rat mitogen-activated protein kinase phosphatase 2 gene.

Mitogen-activated protein kinase (MAPK) phosphatases (MKPs) are dual specificity protein phosphatases that specifically inactivate MAPKs. Regulated expression of MKPs plays a key role in determining their physiological function. However, little is known about the molecular mechanism of the activation of MKP genes. In this study, we cloned the rat MKP-2 gene and characterized its structure. The MKP-2 gene has four exons and three introns. The organization of exons of the MKP-2 gene is very similar to that of the MKP-1 gene, suggesting that MKP-1 and MKP-2 are derived from the same ancestral gene. We identified multiple transcription start sites (TSSs) for the MKP-2 gene. There is no functional TATA motif in the 5' proximal region of the TSSs. Instead, this region is highly GC-rich and has two putative Sp1 sites. A 1.8 kb 5' flanking region of the MKP-2 gene is sufficient to mediate transcriptional activation of the luciferase reporter gene by phorbol ester in GH3 cells. These results provide essential information about structural organization and regulatory sequences of the MKP-2 gene for further investigation of the molecular mechanisms of MKP-2 induction by extracellular stimuli.