Etiology of acute lower respiratory tract infection in Central Australian Aboriginal children

BACKGROUND

Aboriginal children in central Australia have attack rates for acute lower respiratory tract infection (ALRI) that are similar to those in developing countries. Although mortality rates are much lower than in developing countries, morbidity is high and ALRI is still the leading cause of hospitalization. However, there are no data on the etiology of ALRI in this population.

METHODS

We prospectively studied 322 cases of ALRI in 280 Aboriginal children admitted to the hospital. Blood, urine and nasopharyngeal aspirate samples were examined for evidence of bacterial, viral and chlamydial infection.

RESULTS

The combination of blood culture, viral studies and chlamydial serology provided at least 1 etiologic agent in 170 of 322 (52.5%) cases. Assays for pneumolysin immune complex and pneumolysin antibody increased etiologic diagnosis to 219 (68.0%). Blood cultures were positive in 6% but pneumolysin immune complex and pneumolysin antibody studies were positive in one-third of cases. Evidence of viral infection was present in 155 (48%) of cases compared with 12% in controls (P < 001). There were only 7 possible cases and 2 definite cases of Chlamydia trachomatis and 3 cases of Chlamydia pneumoniae. Coinfection was common in these children.

CONCLUSION

These findings have implications for both standard treatment protocols and vaccine strategies. The high rate of coinfection may make it difficult to develop simple clinical predictors of bacterial infection. In the setting of a developed country with efficient patient evacuation services, management algorithms that focus on disease severity and need for hospital referral will be most useful to health staff in remote communities. Pneumococcal conjugate vaccines will be required to reduce the high attack rate of pneumococcal disease.

Antagonists of the platelet P2T receptor: a novel approach to antithrombotic therapy

The platelet P2T receptor plays a major role in platelet aggregation, and its antagonists are predicted to have significant therapeutic potential as antithrombotic agents. We have explored analogues of adenosine triphosphate (ATP), which is a weak, nonselective but competitive P2T receptor antagonist. Modification of the polyphosphate side chain to prevent breakdown to the agonist adenosine diphosphate (ADP) and substitution of the adenine moiety to enhance affinity and selectivity for the P2T receptor led to the identification of 10e (AR-C67085MX), having an IC50 of 2.5 nM against ADP-induced aggregation of human platelets. Compound 10e was the first very potent antagonist of the P2T receptor, with a selectivity for that subtype of the P2 receptor family of >1000-fold. Further modification of the structure produced compound 10l (AR-C69931MX) having an IC50 of 0.4 nM. In vivo, at maximally effective antithrombotic doses, there is little prolongation of bleeding time (1.4-fold), which is in marked contrast to the 5-6-fold found with GPIIb/IIIa antagonists.

Identification and cloning of a novel cellular protein Naf1, Nef-associated factor 1, that increases cell surface CD4 expression

The nef gene of human and simian immunodeficiency virus is a key factor in acquired immunodeficiency syndrome pathogenesis and virus replication. Several Nef-induced phenomena, including the down-regulation of CD4 molecule, have been previously reported. In this study, we have identified and cloned a novel cellular protein Naf1 (Nef-associated factor 1), which associated with Nef in the yeast two-hybrid system and pull-down assay. The Naf1 gene generates two isoforms (Naf1alpha and beta) containing four coiled-coil structures. The Naf1 mRNA is ubiquitously expressed in human tissues with strong expression in peripheral blood lymphocytes and spleen. Naf1 overexpression increased cell surface CD4 expression. Nef suppressed this Naf1-induced augmentation of CD4 expression, providing a novel mode of Nef action in CD4 down-regulation.

Assessing smoke-free workplaces in Wisconsin municipal and county government buildings, 1997

Passive smoke has been shown to cause cancer and heart disease in humans. We surveyed all Wisconsin cities and villages in 1997 to determine their clean indoor air policies in government-owned buildings. By 1997, 62% of cities and villages and 100% of counties had enacted a clean indoor air ordinance or policy. Smoking is completely banned in 26% of all city and village buildings and 49% of county buildings in the state. This survey shows that an increasing proportion of government worksites in Wisconsin are enacting clean indoor air policies to protect their employees and the public from the health effects of passive smoke.

Substrate specificity of the SpCCE1 holliday junction resolvase of Schizosaccharomyces pombe

SpCCE1 from Schizosaccharomyces pombe is an endonuclease that resolves Holliday junctions in vitro. SpCCE1 also binds and cleaves a range of other DNAs (Y-junction; flap; and flayed, nicked, and partial duplexes) with varying efficiency. Cleavage sites are always 3' of thymine nucleotides positioned at or close to the branch point or strand interruption. SpCCE1's favored substrate is the X-junction. Up to two dimers of SpCCE1 can bind concurrently to the same X-junction at its crossover point. From mixing experiments of SpCCE1 and the Escherichia coli RuvA protein, we show that each dimer of SpCCE1 binds to a different face of the X-junction and that both are seemingly competent for strand cleavage. We propose that this provides a mechanism whereby SpCCE1 can scrutinize all four junction strands simultaneously for cleavable thymine nucleotides. SpCCE1 appears to resolve X-junctions by a nick and counter-nick mechanism. Therefore, to ensure a high probability of bilateral strand cleavage, SpCCE1 has a relatively long lifetime on X-junctions. This mechanism has the drawback of limiting dissociation from noncleavable junctions. We discuss why this might not be a problem in vivo.

Molecular basis of transient outward potassium current downregulation in human heart failure: a decrease in Kv4.3 mRNA correlates with a reduction in current density

BACKGROUND

Despite advances in medical therapy, congestive heart failure remains a major cause of death in the developed world. A disproportionate number of the deaths of patients with heart failure are sudden and presumed to be arrhythmic. Heart failure in humans and in animal models is associated with prolongation of the action potential duration (APD), the result of downregulation of K+ currents-prominently, the Ca2+-independent transient outward current (Ito). The mechanism for the reduction of Ito in heart failure is unknown. The K+ channel alpha-subunit Kv4.3, a homolog of the Drosophila Shal family, is most likely to encode all or part of the native cardiac Ito in humans.

METHODS AND RESULTS

We used ribonuclease protection assays and whole-cell electrophysiological recording to study changes in the level of Kv4.3 mRNA and Ito in human tissues and isolated ventricular myocytes, respectively. We found that the level of Kv4.3 mRNA decreased by 30% in failing hearts compared with nonfailing controls. Furthermore, this reduction correlated with the reduction in peak Ito density measured in ventricular myocytes isolated from adjacent regions of the heart. There was no significant change in the steady-state level of any other mRNA studied (HERG, Kv1.4, Kir2.1, Kvss1.3, and the alpha1C subunit of the Ca2+ channel). mRNAs encoding Kv1.2, Kv1.5, and Kv2.1 were found in low abundance in human ventricle.

CONCLUSIONS

These data provide further support for the hypothesis that Kv4.3 encodes all or part of the native cardiac Ito in humans and that part of the downregulation of this current in heart failure may be transcriptionally regulated.

Mutations in the Treacher Collins syndrome gene lead to mislocalization of the nucleolar protein treacle

Treacher Collins syndrome (TCS) is an autosomal dominant disorder of craniofacial development, the features of which include conductive hearing loss and cleft palate. The TCS gene ( TCOF1 ), which is localized to chromosome 5q32-q33.1, recently has been identified by positional cloning. Analysis of TCOF1 revealed that the majority of TCS mutations result in the creation of a premature termination codon. The function of the predicted protein, treacle, is unknown, although indirect evidence from database analyses suggests that it may function as a shuttling nucleolar phosphoprotein. In the current study, we provide the first direct evidence that treacle is a nucleolar protein. An antibody generated against treacle shows that it localizes to the nucleolus. Fusion proteins tagged to a green fluorescent protein reporter were shown to localize to different compartments of the cell when putative nuclear localization signals were deleted. Parallel experiments using conserved regions of the murine homologue of TCOF1 confirmed these results. Site-directed mutagenesis has been used to recreate mutations observed in individuals with TCS. The resulting truncated proteins are mislocalized within the cell, which further supports the hypothesis that an integral part of treacle's function involves shuttling between the nucleolus and the cytoplasm. TCS is, therefore, the first Mendelian disorder resulting from mutations which lead to aberrant expression of a nucleolar protein.

The effect of oral selenium supplementation on human sperm motility

OBJECTIVES

To determine whether the decline in selenium intake and selenium status in men in the West of Scotland might be a contributory factor to male subfertility.

PATIENTS AND METHODS

Two semen samples were collected from patients attending a subfertility clinic and those patients with samples showing reduced motility were invited to participate in an ethically approved double-blind clinically controlled trial with informed consent. Sixty-nine patients were recruited and received either placebo, selenium alone or selenium plus vitamins A, C and E daily for 3 months. A further semen sample was collected at the end of the trial. Plasma selenium status was determined at the beginning and end of the trial period, as was total sperm density and motility.

RESULTS

Plasma selenium concentrations were significantly (P < 0.001) higher in both selenium-treated groups than in controls. No significant effect of treatment on sperm density was recorded. Sperm motility increased in both selenium-treated groups, in contrast to a slight decline in the placebo group, but the difference was not significant. However, as the provision of additional vitamins had no effect on any variable measured it was considered justified to combine the two selenium-treated groups and compare them with the placebo treatment. On this basis, selenium treatment significantly (P < 0.002) increased plasma selenium concentrations and sperm motility (P = 0.023) but sperm density was again unaffected. Five men (11%) achieved paternity in the treatment group, in contrast to none in the placebo group.

CONCLUSION

This trial confirms the result of an earlier study, that selenium supplementation in subfertile men with low selenium status can improve sperm motility and the chance of successful conception. However, not all patients responded; 56% showed a positive response to treatment. The low selenium status of patients not supplemented again highlights the inadequate provision of this essential element in the Scottish diet.

Adult supraglottitis: an important cause of airway obstruction

Supraglottitis in the adult can progress rapidly to complete airway obstruction. Successful management requires a high index of clinical suspicion at initial presentation and anticipation of a fulminant course. All cases should be assessed in a resuscitation area by senior medical staff.

Assessment of the reproducibility of clinical coding in routinely collected hospital activity data: a study in two hospitals

BACKGROUND

The aim of the study was to assess the reproducibility of clinical coding in two National Health Service hospitals within North West Thames region.

METHODS

A retrospective audit was carried out, of clinical coding in hospital episode statistics, involving comparison of the codes assigned by local staff with those assigned by members of an external team unaware of the locally assigned codes. Where local and external coders disagreed, the records were reviewed for a third time by a further independent coder. The subjects were a random sample of 1607 non-maternity, non-psychiatric admissions occurring between 1991 and 1993, stratified for year and type of disease (asthma, diabetes, appendicitis, fractured femur and 'general'--a random selection of any diagnoses). The main outcome measures were the levels of exact agreement between local and external teams over codes for main diagnosis and procedure, and the level of approximate agreement (over the first three characters of the ICD-9 code for diagnosis and the letter and first two digits of the OPCS-4 code for procedure). For disagreements, the outcome measure was the level of agreement between the 'third' coder and the local and external coders.

RESULTS

For the main diagnosis in the 'general' group at hospital A, internal and external coders agreed exactly in 43 per cent of the admissions examined and agreed 'approximately' in 55 per cent (kappa = 0.54). For hospital B the corresponding figures were 60 per cent and 72 per cent (kappa = 0.72). Approximate agreement was higher for the specific diseases considered, particularly for asthma (A: 86 per cent; B: 91 per cent) and fractured femur (A: 84 per cent; B: 89 per cent). For the main procedure at hospital A, there was exact agreement for 58 per cent and approximate agreement for 70 per cent (kappa = 0.66). For hospital B, the corresponding figures were 76 per cent and 83 per cent (kappa = 0.80). In cases of disagreement over the first three digits of the ICD-9 code for main diagnosis, the third coder disagreed with both local and external coders in 53 per cent at hospital A and 38 per cent at hospital B. Agreement was slightly better for discharges in 1992-1993 than in 1991-1992.

CONCLUSIONS

The full clinical codes in NHS hospital episode statistics (HES) data should be treated with caution. The first three characters of ICD-9 codes for diagnoses and the OPCS-4 codes for procedures were more reliable. For some specific conditions such as asthma and fractured femur, reliability of the first three characters is much higher (for example, 86 per cent and 91 per cent for asthma in the two hospitals), but for the full codes can be worse. Secondary diagnoses or comorbidities may be significantly undercoded. A higher level of agreement in 1992-1993 than in 1991-1992 suggests that coding may be improving.

A new Holliday junction resolving enzyme from Schizosaccharomyces pombe that is homologous to CCE1 from Saccharomyces cerevisiae

The resolution of Holliday junctions is a critical stage in recombination. We describe the identification and initial biochemical characterisation of a new Holliday junction resolvase from Schizosaccharomyces pombe. Resolvase activity was initially detected in partially purified cell-free extracts of S. pombe. Resolution of X-junction DNA occurred by the introduction of symmetrical cuts in strands of the same polarity. All cuts occurred 3' of thymine nucleotides with a possible preference for cleavage one nucleotide 3' from the point of strand crossover. During the course of these studies, a potential S. pombe homologue of the Saccharomyces cerevisiae Cruciform Cutting Endonuclease I was identified in the database (SpCCE1). The gene was cloned by PCR, overexpressed in Escherichia coli and its product purified as a His-tagged fusion protein. Purified SpCCE1 binds to X-junctions in a structure-specific manner and resolves them to nicked linear duplex products that are repairable by DNA ligase. SpCCE1 cuts X-junctions in precisely the same way as the resolvase activity from partially purified extracts of S. pombe, indicating that they are probably the same. Finally, we show that SpCCE1 can function as a Holliday junction resolvase in vivo by its ability to complement a resolvase-deficient strain of E. coli.

Tumors around implants

In 1989, A. G. Apley recommended cautious surveillance of malignant tumors that developed in association with orthopaedic implants. This retrospective review of the Bristol Bone Tumour Register between 1980 and 1992 reports on 240 malignant soft tissue sarcomas. Eighteen developed in the thigh region of patients more than 50 years old, and 4 of these developed in the soft tissues around a hip arthroplasty.

Clinical features in four patients with Angelman syndrome resulting from paternal uniparental disomy

Angelman syndrome (AS) is a complex neurological disorder with different genetic aetiologies. It is not known whether the clinical features vary depending on the genetic mechanism. We report four patients with AS owing to uniparental disomy (UPD). There were two males and two females, with a mean age of 8 years (range 7 to 11 years). All patients had a happy disposition, hyperactive behaviour, and the characteristic facial phenotype of AS, but in three there was a normal head circumference, two had epilepsy, ataxic movements were mild in three, the mean age of onset of walking was 2.4 years, and there was some sign language in all four patients. Our cases add further weight to the previously reported impressions of a milder phenotype in cases of AS resulting from UPD than in deleted AS patients. Patients suspected of having AS, but who are considered atypical, warrant DNA testing.

Atelosteogenesis syndromes: a review, with comments on their pathogenesis

The clinical, radiographic, and morphological findings in 25 cases of atelosteogenesis and boomerang dysplasia have been reviewed. The review confirms the nosologic grouping of atelosteogenesis type I with boomerang dysplasia and the clinical and radiographic overlap of features between atel- osteogenesis I and atelosteogene- sis II (synonymous with De la Chapelle dysplasia) and a group of patients with atelosteogenesis type III. A common pathogenesis is suggested for atelosteogenesis type I and boomerang dysplasia. A marked excess of male fetuses with boomerang dysplasia was observed. Atelosteogenesis type II shows distinctive chondro-osseous histopathology with a major disturbance in cartilage matrix macromolecules. An overlap of phenotypic, radiographic, morphological, and cartilage histochemical features with those observed in diastrophic dysplasia and achondrogenesis type IB suggests that atelosteogenesis type II has common pathogenetic features with disorders of sulfation of connective tissue matrix macro- molecules.

Sequence analysis, identification of evolutionary conserved motifs and expression analysis of murine tcof1 provide further evidence for a potential function for the gene and its human homologue, TCOF1

The gene mutated in Treacher Collins syndrome, an autosomal dominant disorder of facial development, has recently been cloned. While the function of the predicted protein, Treacle, is unknown, it has been shown to share a number of features with the highly phosphorylated nucleolar phosphoproteins, which play a role in nucleolar-cytoplasmic transport. In the current study, the murine homologue of the Treacher Collins syndrome gene has been isolated and shown to encode a low complexity, serine/alanine-rich protein of 133 kDa. Interspecies comparison indicates that the proteins display 61.5% identity, with the level of conservation being greatest in the regions of acidic/basic amino acid repeats and nuclear localization signals. These features are shared with the nucleolar phosphoproteins. Confirmation that the gene isolated in the current study is orthologous with the Treacher Collins syndrome gene was provided by the demonstration that it mapped to central mouse chromosome 18 in a conserved syntenic region with human chromosome 5q21-q33. Expression analysis in the mouse indicated that the gene was expressed in a wide variety of embryonic and adult tissues. Peak levels of expression in the developing embryo were observed at the edges of the neural folds immediately prior to fusion, and also in the developing branchial arches at the times of critical morphogenetic events. These observations support a role for the gene in the development of the craniofacial complex and provide further evidence that the gene encodes a protein which may be involved in nucleolar-cytoplasmic transport.

Identification of the complete coding sequence and genomic organization of the Treacher Collins syndrome gene

Treacher Collins syndrome (TCS) is an autosomal dominant disorder of craniofacial development, the features of which include conductive hearing loss and cleft palate. Recently, the demonstration of a series of 10 mutations within a partial-length cDNA clone have indicated that the TCS gene (TCOF1) has been positionally cloned. Although it has been shown that the gene is expressed in a wide variety of fetal and adult tissues, database sequence comparisons have failed to provide significant information on the function of the gene. In the current investigation, a combination of cDNA library screening and rapid amplification of cDNA ends has permitted the isolation of the complete coding sequence of TCOF1, which is encoded by 26 exons and predicts a low complexity, serine/alanine-rich protein of approximately 144 kD. The use of a variety of bioinformatics tools has resulted in the identification of repeated units within the gene, each of which maps onto an individual exon. The predicted protein Treacle contains numerous potential phosphorylaiton sites, a number of which map to similar positions within the repeated units, and shows weak but significant homology to the nucleolar phosphoproteins. Although the precise function of Treacle remains unknown, these observations suggest that phosphorylation may be important for its role in early embryonic development and that it may play a role in nucleolar-cytoplasmic shuttling. The information presented in this study will allow continued mutation analysis in families with a history of TCS and should facilitate continued experimentation to shed further light on the function of the gene/protein during development of the craniofacial complex.