Hip fractures among indigenous Western Australians from 1999 to 2009.

BACKGROUND: Minimal trauma hip fractures are prevalent in Australia. The incidence rate and trend of hip fractures in Indigenous Western Australians have not been formally reported. AIMS: To evaluate incidence rates and trend of minimal trauma hip fractures in Indigenous and other Western Australians aged 40 years and over in 1999-2009 METHODS: Hip fracture data were obtained from an administrative database for all hospitalisations in Western Australia. Age-standardised incidence rates were calculated using direct standardisation, and standardised rate ratios were calculated using the indirect method. Trend in incidence rates were calculated using Poisson regression. RESULTS: In 1999-2009, 11,844 admissions for minimal trauma hip fractures were reported among Western Australians aged 40 years and over, of which 201 were recorded as indigenous. The age-standardised hip fracture rate was 273.0 (95% confidence interval (CI) 230.7-315.4) per 100,000 person-years for indigenous adults and 148.8 (95% CI 146.1-151.5) per 100,000 person-years for non-indigenous adults. The standardised morbidity ratio was 2.2 (95% CI 1.9-2.5). Over this period, age-standardised rates increased by an average of 7.2% per year among indigenous adults (P = 0.006), whereas non-indigenous rates fell by an average of 3.4% per year (P < 0.001). The relatively higher rates among indigenous adults were more evident in the younger age groups. CONCLUSION: There is a widening gap in minimal trauma hip fracture rates between indigenous and other Western Australians. This study demonstrates a need for public health review and management strategies to reduce falls and hip fracture in the indigenous community.

Intracranial cause of delirium: computed tomography yield and predictive factors.

BACKGROUND: Computed tomography (CT) of the brain in delirium investigation has a low yield of identifiable causes. We sought to identify the best clinical predictors of an intracranial cause of delirium. METHODS: We performed a case-control study of patients admitted to a delirium unit. Clinical factors of patients with positive findings on scans were compared with those without demonstrated causes. The main outcome measure was intracranial abnormalities accountable for the cause of delirium. RESULTS: During 18 months, there were 300 admissions to the unit. Mean age of patients was 86.6 years. Among 200 patients who proceeded to CT scanning, only 29 demonstrated intracranial pathology accountable for the cause of delirium, with a yield of 14.5%. There were 13 patients with ischaemic stroke, seven with subdural haemorrhage and nine with intracerebral haemorrhage. In multivariate analysis, new neurological deficits (adjusted odds ratio (OR) 18.17, 95% confidence interval (CI) 5.99-55.15), recent falls history (adjusted OR 5.58, 95% CI 1.90-16.42) and decline in conscious level (adjusted OR 4.58, 95% CI 1.33-15.79) were predictors of clinically meaningful radiological findings. Twenty-six of the 29 patients with scans had these three predictors with a sensitivity of 89.7% (95% CI 78.6-100%). CONCLUSION: We identified a history of recent fall as a new independent predictor for clinically relevant intracranial pathology in delirious patients, besides new neurological deficits and decline in conscious state. A flow chart incorporating CT head scanning as part of delirium investigation is proposed.

Observation of two-photon absorption at low power levels using tapered optical fibers in rubidium vapor.

Nonlinear optical effects can be enhanced in tapered optical fibers with diameters less than the wavelength of the propagating light. Here we report on the observation of two-photon absorption using tapered fibers in rubidium vapor at power levels of less than 150 nW. Transit-time broadening produces two-photon absorption spectra with sharp peaks that are very different from conventional line shapes.

Association between Cognitive Function and Clustered Cardiovascular Risk of Metabolic Syndrome in Older Adults at Risk of Cognitive Decline.

OBJECTIVES: Metabolic syndrome (MetS) represents a cluster of obesity and insulin resistance-related comorbidities. Abdominal obesity, hypertension, elevated triglyceride and glucose levels are components of MetS and may have a negative effect on cognitive function, but few cognitive studies have examined the combined risk severity. We sought to determine which specific cognitive abilities were associated with MetS in older adults at risk of cognitive decline. DESIGN: Cross-sectional study. PARTICIPANTS: 108 AIBL Active participants with memory complaints and at least one cardiovascular risk factor. MEASUREMENTS: Cardiovascular parameters and blood tests were obtained to assess metabolic syndrome criteria. The factors of MetS were standardized to obtain continuous z-scores. A battery of neuropsychological tests was used to evaluate cognitive function. RESULTS: Higher MetS z-scores were associated with poorer global cognition using ADAS-cog (adjusted standardized beta=0.26, SE 0.11, p<0.05) and higher Trail Making B scores (adjusted beta=0.23, SE 0.11, p<0.05). Higher MetS risk was related to lower cognitive performance. CONCLUSION: Combined risk due to multiple risk factors in MetS was related to lower global cognitive performance and executive function. A higher MetS risk burden may point to opportunities for cognitive testing in older adults as individuals may experience cognitive changes.

Therapeutic control of hepatitis C virus: the role of neutralizing monoclonal antibodies.

Liver failure associated with hepatitis C virus (HCV) accounts for a substantial portion of liver transplantation. Although current therapy helps some patients with chronic HCV infection, adverse side effects and a high relapse rate are major problems. These problems are compounded in liver transplant recipients as reinfection occurs shortly after transplantation. One approach to control reinfection is the combined use of specific antivirals together with HCV-specific antibodies. Indeed, a number of human and mouse monoclonal antibodies to conformational and linear epitopes on HCV envelope proteins are potential candidates, since they have high virus neutralization potency and are directed to epitopes conserved across diverse HCV genotypes. However, a greater understanding of the factors contributing to virus escape and the role of lipoproteins in masking virion surface domains involved in virus entry will be required to help define those protective determinants most likely to give broad protection. An approach to immune escape is potentially caused by viral infection of immune cells leading to the induction hypermutation of the immunoglobulin gene in B cells. These effects may contribute to HCV persistence and B cell lymphoproliferative diseases.

Reversible cleavage and ligation of hepatitis delta virus RNA.

A 148-nucleotide subfragment of hepatitis delta virus RNA was shown to undergo cleavage and ligation reversibly. The direction of the reaction is determined by the presence or absence of Mg2+ ions, with the presence of Mg2+ favoring the cleavage reaction. Ligation requires specific conformation of the RNA molecules involved and occurs only between two cleaved RNA fragments that are still held together by hydrogen bonds. The ligation reaction occurs rapidly on removal of Mg2+ by EDTA. This represents a new class of RNA enzymes.

Inhibition of the interferon-inducible protein kinase PKR by HCV E2 protein.

Most isolates of hepatitis C virus (HCV) infections are resistant to interferon, the only available therapy, but the mechanism underlying this resistance has not been defined. Here it is shown that the HCV envelope protein E2 contains a sequence identical with phosphorylation sites of the interferon-inducible protein kinase PKR and the translation initiation factor eIF2alpha, a target of PKR. E2 inhibited the kinase activity of PKR and blocked its inhibitory effect on protein synthesis and cell growth. This interaction of E2 and PKR may be one mechanism by which HCV circumvents the antiviral effect of interferon.

Interaction of RAFT1 with gephyrin required for rapamycin-sensitive signaling.

RAFT1 (rapamycin and FKBP12 target 1; also called FRAP or mTOR) is a member of the ATM (ataxia telangiectasia mutated)-related family of proteins and functions as the in vivo mediator of the effects of the immunosuppressant rapamycin and as an important regulator of messenger RNA translation. In mammalian cells RAFT1 interacted with gephyrin, a widely expressed protein necessary for the clustering of glycine receptors at the cell membrane of neurons. RAFT1 mutants that could not associate with gephyrin failed to signal to downstream molecules, including the p70 ribosomal S6 kinase and the eIF-4E binding protein, 4E-BP1. The interaction with gephyrin ascribes a function to the large amino-terminal region of an ATM-related protein and reveals a role in signal transduction for the clustering protein gephyrin.

HDV RNA replication: ancient relic or primer?

HDV replicates its circular RNA genome using a double rolling-circle mechanism and transcribes a hepatitis delta antigen-encodeing mRNA from the same RNA template during its life cycle. Both processes are carried out by RNA-dependent RNA synthesis despite the fact that HDV does not encode an RNA-dependent RNA polymerase (RdRP). Cellular RNA polymerase II has long been implicated in these processes. Recent findings, however, have shown that the syntheses of genomic and antigenomic RNA strands have different metabolic requirements, including sensitives to alpha-amanitin and the site of synthesis. Evidence is summarized here for the involvement of other cellular polymerases, probably pol I, in the synthesis of antigenomic RNA strand. The ability of mammalian cells to replicate HDV RNA implies that RNA-dependent RNA synthesis was preserved throughout evolution.

RNA conformational requirements of self-cleavage of hepatitis delta virus RNA.

Hepatitis delta virus (HDV) RNA subfragments undergo self-cleavage at varying efficiencies. We have developed a procedure of using repeated cycles of heat denaturation and renaturation of RNA to achieve a high efficiency of cleavage. This effect can also be achieved by gradual denaturation of RNA with heat or formamide. These results suggest that only a subpopulation of the catalytic RNA molecules assumes the active conformation required for self-cleavage. This procedure could be of general use for detecting catalytic RNA activities.

RNA-Dependent replication and transcription of hepatitis delta virus RNA involve distinct cellular RNA polymerases.

Cellular DNA-dependent RNA polymerase II (pol II) has been postulated to carry out RNA-dependent RNA replication and transcription of hepatitis delta virus (HDV) RNA, generating a full-length (1.7-kb) RNA genome and a subgenomic-length (0.8-kb) mRNA. However, the supporting evidence for this hypothesis was ambiguous because the previous experiments relied on DNA-templated transcription to initiate HDV RNA synthesis. Furthermore, there is no evidence that the same cellular enzyme is involved in the synthesis of both RNA species. In this study, we used a novel HDV RNA-based transfection approach, devoid of any artificial HDV cDNA intermediates, to determine the enzymatic and metabolic requirements for the synthesis of these two RNA species. We showed that HDV subgenomic mRNA transcription was inhibited by a low concentration of alpha-amanitin (<3 microgram/ml) and could be partially restored by an alpha-amanitin-resistant mutant pol II; however, surprisingly, the synthesis of the full-length (1.7-kb) antigenomic RNA was not affected by alpha-amanitin to a concentration higher than 25 microgram/ml. By several other criteria, such as the differing requirement for the de novo-synthesized hepatitis delta antigen and temperature dependence, we further showed that the metabolic requirements of subgenomic HDV mRNA synthesis are different from those for the synthesis of genomic-length HDV RNA and cellular pol II transcripts. The synthesis of the two HDV RNA species could also be uncoupled under several different conditions. These findings provide strong evidence that pol II, or proteins derived from pol II transcripts, is involved in mRNA transcription from the HDV RNA template. In contrast, the synthesis of the 1.7-kb HDV antigenomic RNA appears not to be dependent on pol II. These results reveal that there are distinct molecular mechanisms for the synthesis of these two RNA species.

Linezolid-induced optic neuropathy: a mitochondrial disorder?

We report a case of bilateral mitochondrial optic neuropathies secondary to long-term linezolid treatment, show the nature of recovery, review the findings in the literature and propose a potential mitochondrial mechanism for linezolid-induced mitochondrial optic neuropathy. This is an observational case report and literature review with presentation of the clinical course of linezolid mitochondrial optic neuropathies through clinical and psychophysical documentation. Main outcome measures included: visual acuity, funduscopical examinations and peripapillary retinal nerve fibre layer (PRNFL) optical coherence tomography (OCT). A 6-year-old boy presented with bilateral optic neuropathies secondary to 1 year of linezolid treatment for osteomyelitis of the mandible. On presentation, visual acuities were 20/400 in both eyes, with considerable optic disc oedema, hyperaemia and PRNFL swelling confirmed by OCT. 2 weeks after the discontinuation of linezolid, visual acuities returned to 20/25 in both eyes, with reduction in the optic disc oedema, hyperaemia and PRNFL swelling. 3 months after the discontinuation of linezolid treatment, visual acuities were stable at 20/20 in both eyes, with a marked decrease in PRNFL swelling confirmed by OCT, and the development of mild temporal optic disc pallor in both eyes. Doctors should be aware of impairments of vision among patients on long-term linezolid treatment and promptly discontinue treatment to prevent irreversible vision loss. The development and resolution of bilateral optic neuropathies with considerable PRNFL swelling in this patient provide insight into the more general rubric of mitochondrial optic neuropathies.

Intrahepatic lymphocyte phenotypes in hepatitis C virus infection: a comparison between cirrhotic and non-cirrhotic livers.

AIM: The pathogenesis of viral hepatitis involves the activation of cellular immunity, including intrahepatic lymphocytes (IHL). Lym-phocyte phenotypes play a fundamental role in the pathogenesis of chronic hepatitis C virus (HCV) infection, the progression of liver fibrosis and subsequent hepatocellular carcinoma. The aim of this study was to evaluate the frequency of intrahepatic mononuclear cell phenotypes in patients with chronic HCV. Another aim was to assess the relationship of nonparenchymal cells with liver fibrosis. METHODS: Liver fibrosis was evaluated with the Histologic Activity Index. Fourteen liver biopsies showed mild fibrosis (group 1), and 11 bridging fibrosis (group 2). Fourteen samples were explants from HCV patients who underwent liver transplantation (group 3). CD4 and CD8 T-lymphocytes, CD20 (B lymphocytes), CD16 (macrophage), and CD57 (NK) cells were detected using monoclonal antibodies on paraffin-embedded tissue. RESULTS: A minority of lobular cells stained for T- or B-lymphocytes. Most lobular cells stained with macrophage antibodies, and were more common in bridging fibrosis, compared to mild fibrosis. The percentages of lobular CD4 and CD8 cells were significantly lower in regenerative nodules of cirrhotic livers. There was a strong negative correlation between lobular CD8 and fibrosis score (R= -0.65), and a strong positive correlation between CD16-stained mononuclear cells (macrophages) and fibrosis score (R=0.66). In portal and periportal areas, CD4 but not CD8 lymphocytes decreased in parallel with fibrosis. B-lymphocytes were more commonly found in the portal areas than in the lobule. CD57-positive cells were rare in both lobule and portal areas, and their frequency was not different in the three groups studied. CONCLUSIONS: In hepatitis C, lobular mononuclear cells are mostly macrophages and appear associated with bridging fibrosis. Cirrhotic livers display significantly lower numbers of lobular CD4 and CD8 lymphocytes. This finding could help explain a decrease in immune surveillance and the promotion of neoplastic growth in HCV-associated cirrhosis.

Viral and cellular proteins involved in coronavirus replication.

As the largest RNA virus, coronavirus replication employs complex mechanisms and involves various viral and cellular proteins. The first open reading frame of the coronavirus genome encodes a large polyprotein, which is processed into a number of viral proteins required for viral replication directly or indirectly. These proteins include the RNA-dependent RNA polymerase (RdRp), RNA helicase, proteases, metal-binding proteins, and a number of other proteins of unknown function. Genetic studies suggest that most of these proteins are involved in viral RNA replication. In addition to viral proteins, several cellular proteins, such as heterogeneous nuclear ribonucleoprotein (hnRNP) A1, polypyrimidine-tract-binding (PTB) protein, poly(A)-binding protein (PABP), and mitochondrial aconitase (m-aconitase), have been identified to interact with the critical cis-acting elements of coronavirus replication. Like many other RNA viruses, coronavirus may subvert these cellular proteins from cellular RNA processing or translation machineries to play a role in viral replication.

Protein 4.1N binding to nuclear mitotic apparatus protein in PC12 cells mediates the antiproliferative actions of nerve growth factor.

Protein 4.1N is a neuronal selective isoform of the erythrocyte membrane cytoskeleton protein 4.1R. In the present study, we demonstrate an interaction between 4.1N and nuclear mitotic apparatus protein (NuMA), a nuclear protein required for mitosis. The binding involves the C-terminal domain of 4.1N. In PC12 cells treatment with nerve growth factor (NGF) elicits translocation of 4. 1N to the nucleus and promotes its association with NuMA. Specific targeting of 4.1N to the nucleus arrests PC12 cells at the G1 phase and produces an aberrant nuclear morphology. Inhibition of 4.1N nuclear translocation prevents the NGF-mediated arrest of cell division, which can be reversed by overexpression of 4.1N. Thus, nuclear 4.1N appears to mediate the antiproliferative actions of NGF by antagonizing the role of NuMA in mitosis.

Nucleoside kinase activities of Chinese hamster ovary cells.

Chinese hamster ovary (CHO) cells and appropriate drug-resistant mutants derived from them have been analyzed for nucleoside kinase activities relevant to the phosphorylation of adenosine, deoxyadenosine, deoxyguanosine and deoxycytidine and for resistance to a variety of nucleoside analogs. Fractionation of extracts by DEAE-cellulose chromatography revealed three major peaks of activity. Adenosine kinase (ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20), the first to elute from the column is responsible for the majority of the deoxyadenosine phosphorylation in cell extracts and, according to resistance data, appears to phosphorylate most adenosine analogs tested, including 9-beta-D-arabinosyladenine (ara-A). A deoxyguanosine kinase, the second enzyme to elute from the column, was responsible for the majority of deoxyguanosine and deoxyinosine phosphorylation in cell extracts. The function of this enzyme in cell metabolism is unclear. 2-Chlorodeoxyadenosine, on the other hand, appeared from resistance data to be phosphorylated, at least in part, by deoxycytidine kinase (ATP:deoxycytidine 5'-phosphotransferase, EC 2.7.1.74), which in cell extracts could also phosphorylate deoxyguanosine and deoxyadenosine, though much less efficiently than deoxycytidine.

Neural actions of immunophilin ligands.

Immunophilins, protein receptors for immunosuppressant drugs such as cyclosporin A and FK506, are enriched far more in the brain than in the immune system. Drug-immunophilin complexes bind to calcineurin, inhibiting its phosphatase activity and leading to immunosuppressant effects. The immunophilin FKBP-12 (FK506 binding protein, 12 kDa) forms a complex with the ryanodine and inositol (1,4,5) trisphosphate (IP3) receptors to regulate their physiological release of intracellular Ca2+. Here, Solomon Snyder and colleagues describe how non-immunosuppressant as well as immunosuppressant immunophilin ligands are neurotrophic for numerous classes of damaged neurones, both in culture systems and intact animals. Their ability to stimulate functional regrowth of damaged sciatic, cortical cholinergic, dopamine and 5-HT neurones may have therapeutic relevance.

Sequence and structure of the catalytic RNA of hepatitis delta virus genomic RNA.

Human hepatitis delta virus (HDV) RNA has been shown to contain a self-catalyzed cleavage activity. The sequence requirement for its catalytic activity appears to be different from that of other known ribozymes. In this paper, we define the minimum contiguous sequence and secondary structure of the HDV genomic RNA required for the catalytic activity. By using nested-set deletion mutants, we have determined that the essential sequence for the catalytic activity is contained within no more than 85 nucleotides of HDV RNA. These results are in close agreement with the previous determinations and confirmed the relative insignificance of the sequence at the 5' side of the cleavage site. The smallest catalytic RNA, representing HDV genomic RNA nucleotide positions 683 to 770, was used as the basis for studying the secondary structure requirements for catalytic activity. Analysis of the RNA structure, using RNase V1, nuclease S1 and diethylpyrocarbonate treatments showed that this RNA contains at least two stem-and-loop structures. Other larger HDV RNA subfragments containing the catalytic activity also have a very similar secondary structure. By performing site-specific mutagenesis studies, it was shown that one of the stem-and-loop structures could be deleted to half of its original size without affecting the catalytic activity. In addition, the other stem-and-loop contained a six base-pair helix, and the structure, rather than the sequence, of this helix was required for the catalytic activity. However, the structure of a portion of the stem-and-loop remains uncertain. We also report that this RNA can be divided into two separate molecules, which alone did not have cleavage activity but, when mixed, one of the RNAs could be cleaved in trans. This study thus reveals some features of the secondary structure of the HDV genomic RNA involved in self-catalyzed cleavage. A model of this RNA structure is presented.

Neural roles of immunophilins and their ligands.

The immunophilins are a family of proteins that are receptors for immunosuppressant drugs, such as cyclosporin A, FK506, and rapamycin. They occur in two classes, the FK506-binding proteins (FKBPs), which bind FK506 and rapamycin, and the cyclophilins, which bind cyclosporin A. Immunosuppressant actions of cyclosporin A and FK506 derive from the drug-immunophilin complex binding to and inhibiting the phosphatase calcineurin. Rapamycin binds to FKBP and the complex binds to Rapamycin And FKBP-12 Target (RAFT). RAFT affects protein translation by phosphorylating p70-S6 kinase, which phosphorylates the ribosomal S6 protein, and 4E-BP1, a repressor of protein translation initiation. Immunophilin levels are much higher in the brain than in immune tissues, and levels of FKBP12 increase in regenerating neurons in parallel with GAP-43. Immunophilin ligands, including nonimmunosuppressants that do not inhibit calcineurin, stimulate regrowth of damaged peripheral and central neurons, including dopamine, serotonin, and cholinergic neurons in intact animals. FKPB12 is physiologically associated with the ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors and regulates their calcium flux. By influencing phosphorylation of neuronal nitric oxide synthase, FKBP12 regulates nitric oxide formation, which is reduced by FK506.