Quantitative low-energy ion beam characterization by beam profiling and imaging via scintillation screens.

This study presents the imaging and characterization of low-current ion beams in the neutralized state monitored via single crystal YAG:Ce (Y3Al5O12) scintillators. To validate the presented beam diagnostic tool, Faraday cup measurements and test etchings were performed. Argon ions with a typical energy of 1.0 keV were emitted from an inductively coupled radio-frequency (13.56 MHz) ion beam source with total currents of some mA. Different beam properties, such as, lateral ion current density, beam divergence angle, and current density in pulsed ion beams have been studied to obtain information about the spatial beam profile and the material removal rate distribution. We observed excellent imaging properties with the scintillation screen and achieved a detailed characterization of the neutralized ion beam. A strong correlation between the scintillator light output, the ion current density, and the material removal rate could be observed.

Genome-wide association analysis implicates the involvement of eight loci with response to tocilizumab for the treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease affecting the joints. A heterogeneous response to available therapies demonstrates the need to identify those patients likely to benefit from a particular therapy. Our objective was to identify genetic factors associated with response to tocilizumab, a humanized monoclonal antibody targeting the interleukin (IL)-6 receptor, recently approved for treating RA. We report the first genome-wide association study on the response to tocilizumab in 1683 subjects with RA from six clinical studies. Putative associations were identified with eight loci, previously unrecognized as linked to the IL-6 pathway or associated with RA risk. This study suggests that it is unlikely that a major genetic determinant of response exists, and it illustrates the complexity of performing genome-wide association scans in clinical trials.

Polymorphisms in advanced glycosylation end product-specific receptor (AGER) gene, insulin resistance, and type 2 diabetes mellitus.

BACKGROUND: Variants in the advanced glycosylation end product-specific receptor (AGER) gene have been associated with diabetic vasculopathy, however their role in the pathogenesis of insulin resistance and type 2 diabetes mellitus (T2DM) are uncertain. We investigated the relationship of 3 polymorphisms (rs1800625, rs1800624 and rs2070600) in the AGER gene and their haplotypes with T2DM as well as insulin resistance. METHODS: A case-control study from community-based population sample of the Boston metropolitan area was performed in 637 diabetic patients and 596 controls (non-diabetic). The relationships between genotypes and T2DM were evaluated by linear and logistic regression models. Associations with insulin resistance [using corrected insulin response (CIR-30), insulin sensitivity index (ISI-120) and oral glucose tolerance test] were also examined among controls. RESULTS: We found no consistent association between prevalent type 2 diabetes mellitus, and "insulin indices" (CIR-30, ISI-120 and oral glucose tolerance test) and the AGER polymorphisms. The A allele in the rs1800624 was modestly associated with a progressive decrease in CIR-30 levels only among Black controls (p=0.03). CONCLUSIONS: A suggestive association between the A allele in the rs1800624 and CIR-30 levels was found. Further large and multiethnic studies should be performed to clarify these relationships.

Thr40 and Met122 are new partial loss-of-function natural mutations of the human melanocortin 1 receptor.

Activation by melanocortins of the melanocortin 1 receptor (MC1R), expressed in epidermal melanocytes, stimulates melanogenesis. Human MC1R gene loss-of-function mutations are associated with fair skin, poor tanning and increased skin cancer risk. We identified two natural alleles: Ile40Thr, probably associated with skin types I-II, and Val122Met. Val122Met bound [(125)I][Nle(4), D-Phe(7)]-alpha-melanocyte stimulating hormone with lower affinity than the wild-type. Dose-response curves of cAMP accumulation were right-shifted for both forms. The Val122Met form failed to achieve maximal cAMP responses comparable to the wild-type or Ile40Thr receptors. Thus, the Ile40Thr and Val122Met variants are partial loss-of-function natural mutations of MC1R.

In silico mapping of complex disease-related traits in mice.

Experimental murine genetic models of complex human disease show great potential for understanding human disease pathogenesis. To reduce the time required for analysis of such models from many months down to milliseconds, a computational method for predicting chromosomal regions regulating phenotypic traits and a murine database of single nucleotide polymorphisms were developed. After entry of phenotypic information obtained from inbred mouse strains, the phenotypic and genotypic information is analyzed in silico to predict the chromosomal regions regulating the phenotypic trait.

High-throughput SNP allele-frequency determination in pooled DNA samples by kinetic PCR.

We have developed an accurate, yet inexpensive and high-throughput, method for determining the allele frequency of biallelic polymorphisms in pools of DNA samples. The assay combines kinetic (real-time quantitative) PCR with allele-specific amplification and requires no post-PCR processing. The relative amounts of each allele in a sample are quantified. This is performed by dividing equal aliquots of the pooled DNA between two separate PCR reactions, each of which contains a primer pair specific to one or the other allelic SNP variant. For pools with equal amounts of the two alleles, the two amplifications should reach a detectable level of fluorescence at the same cycle number. For pools that contain unequal ratios of the two alleles, the difference in cycle number between the two amplification reactions can be used to calculate the relative allele amounts. We demonstrate the accuracy and reliability of the assay on samples with known predetermined SNP allele frequencies from 5% to 95%, including pools of both human and mouse DNAs using eight different SNPs altogether. The accuracy of measuring known allele frequencies is very high, with the strength of correlation between measured and known frequencies having an r(2) = 0.997. The loss of sensitivity as a result of measurement error is typically minimal, compared with that due to sampling error alone, for population samples up to 1000. We believe that by providing a means for SNP genotyping up to thousands of samples simultaneously, inexpensively, and reproducibly, this method is a powerful strategy for detecting meaningful polymorphic differences in candidate gene association studies and genome-wide linkage disequilibrium scans.

Identification of complement factor 5 as a susceptibility locus for experimental allergic asthma.

The prevalence and severity of allergic asthma continue to rise, lending urgency to the search for environmental triggers and genetic substrates. Using microarray analysis of pulmonary gene expression and single nucleotide polymorphism-based genotyping, combined with quantitative trait locus analysis, we identified the gene encoding complement factor 5 (C5) as a susceptibility locus for allergen-induced airway hyperresponsiveness in a murine model of asthma. A deletion in the coding sequence of C5 leads to C5-deficiency and susceptibility. Interleukin 12 (IL-12) is able to prevent or reverse experimental allergic asthma. Blockade of the C5a receptor rendered human monocytes unable to produce IL-12, mimicking blunted IL-12 production by macrophages from C5-deficient mice and providing a mechanism for the regulation of susceptibility to asthma by C5. The role of complement in modulating susceptibility to asthma highlights the importance of immunoregulatory events at the interface of innate and adaptive immunity in disease pathogenesis.

Single-tube genotyping without oligonucleotide probes.

We report the development of a self-contained (homogeneous), single-tube assay for the genotyping of single-nucleotide polymorphisms (SNPs), which does not rely on fluorescent oligonucleotide probes. The method, which we call Tm-shift genotyping, combines allele-specific PCR with the discrimination between amplification products by their melting temperatures (Tm). Two distinct forward primers, each of which contains a 3'-terminal base that corresponds to one of the two SNP allelic variants, are combined with a common reverse primer in a single-tube reaction. A GC-tail is attached to one of the forward allele-specific primers to increase the Tm of the amplification product from the corresponding allele. PCR amplification, Tm analysis, and allele determination of genomic template DNA are carried out on a fluorescence-detecting thermocycler with a dye that fluoresces when bound to dsDNA. We demonstrate the accuracy and reliability of Tm-shift genotyping on 100 samples typed for two SNPs, and recommend it both as a simple and inexpensive diagnostic tool for genotyping medically relevant SNPs and as a high-throughput SNP genotyping method for gene mapping.

Do diabetics remember all they have been taught? A survey of knowledge of insulin-dependent diabetics.

A questionnaire survey of 182 insulin-dependent diabetics aged 12-73 years attending a District General Hospital outpatient clinic revealed limitations in the understanding of their disease, with gaps in their knowledge on most aspects of diabetic management, including simple metabolic details, use of insulin, hypoglycaemic reactions, effects of exercise and illness, urine testing, and diet. Only 4 patients (2%) answered all 34 questions correctly and only 27 (15%) answered 11 key questions accurately. The total number of 'knowledgeable' patients who achieved a score of at least 28 in all, including 9 or more key questions correct, was 96 (53%). The degree of knowledge of our patients was unrelated to age, duration of diabetes, place of original diabetic education or degree of diabetic control as measured by blood glucose or HbA1 levels.

Hyponatraemia associated with pneumonia or bacterial meningitis.

Serum sodium concentrations were measured in 93 children with pneumonia or bacterial meningitis on their admission to hospital. Hyponatraemia (sodium value 134 mmol/l or less) was present in 33 (45%) of the 73 children with pneumonia, and in 10 (50%) of the 20 children with bacterial meningitis. Increased secretion of antidiuretic hormone is common in children with pneumonia, as well as in children with meningitis. The maintenance fluid requirement in these children is usually about 50 ml/kg/per day, and children with hyponatraemia caused by water overload need even lower fluid intakes. In developing countries, most children with pneumonia and meningitis should be managed without intravenous fluid treatment.

Aetiology of pneumonia in children in Goroka Hospital, Papua New Guinea.

To determine the aetiology of pneumonia in 83 children admitted to Goroka Hospital, Papua New Guinea, lung aspirates and blood were cultured for bacteria. Haemophilus infuenzae, Streptococcus pneumoniae, or both, were isolated from 43 (52%) of the children, other bacteria from 8 (10%), and no bacteria from 32 (39%). Of the 32 strains of H influenzae tested, 18 (56%) were non-serotypable, 8 (25%) were serotypes other than type b, and only 6 (19%) were type b. Viruses were isolated from lung or nasopharyngeal aspirates from 18 (29%) of the 62 children for whom viral cultures were done. It seems that, although viruses may initiate infection, death from pneumonia in children in developing countries is often due to H influenzae, S pneumoniae, or both. Antibiotic therapy would prevent many of these deaths. There is an urgent need for vaccines, effective in children less than 6 months old, that protect against all strains of H influenzae, and S pneumoniae.

Treatment of bacterial meningitis in children without intravenous fluids.

It would be easier and cheaper, and there would be less risk of cerebral oedema, if bacterial meningitis could be adequately treated without the intravenous administration of fluid. Fifty children with bacterial meningitis were treated with intramuscular injections of benzyl penicillin, probenecid given orally and chloramphenicol palmitate suspension given orally, and the outcome was evaluated prospectively. Seven (14%) of the 50 children died. In a control group of 50 children with bacterial meningitis treated with the intravenous administration of benzyl penicillin and chloramphenicol sodium succinate, the outcome was determined retrospectively. Twelve (24%) of the 50 children died. The difference in mortality rate was 10% +/- 15.7% (+/- 2 SE), which is not significant. Except in the rare case of a child with shock or persistent vomiting, bacterial meningitis can be effectively treated with six-hourly intramuscular injections of penicillin, and probenecid and chloramphenicol given orally.

Rotavirus infection in young children in the highlands of Papua New Guinea.

Rotavirus infections were detected by electron microscopy examinations in 54 of 66 children (82%) with acute gastroenteritis which necessitated admission to hospital during April to July, 1979, in the Highlands of Papua New Guinea. Longitudinal epidemiological studies may confirm rotavirus infections to be more important aetiolgical agents of childhood gastroenteritis in this region than in many other countries studied to date.

Leukaemoid reaction in Eastern Highlands children.

In the five year period 1973-77, 278 children in Goroka Hospital paediatric ward were found to have a white cell count (W.C.C.) over 30,000/mm3. Of those with a W.C.C. over 40,000/mm3 in 1977 where the outcome was known, 13 of the 17 (76%) died. It is suggested that "leukaemoid reaction" in Highlands children be defined as a total W.C. over 40,000/mm3 that is not due to leukaemia. A leukaemoid reaction is a useful, but grave, prognostic sign. Such children comprise a quarter of all deaths in the Goroka paediatric ward.

Childhood pneumonia at Goroka Hospital.

We have reviewed the clinical presentation of pneumonia to the Goroka paediatric ward. In comparison to survivors, children dying from pneumonia more often (p less than 0.05) had malnutrition (weight-for-age under 80%), anaemia (haemoglobin under 9g%), and a marked leucocytosis (total white cell count over 30,000 cells per c.m.m.). Children dying from pneumonia had been ill for longer and had been given more antibiotics prior to admission. There was no significant difference between children dying from pneumonia and survivors in age distribution, pulse rate, incidence of cardiac failure or duration of stay in hospital. 70% of the children dying from pneumonia at Goroka Hospital are infants under 12 months of age. Pneumococcal vaccine gives a poor antibody response in infants, and overseas studies using lung aspiration suggest that Haemophilus influenzae and Staphylococcus aureus might be causative organisms as well as Streptococcus pneumoniae. A study to determine the aetiology of pneumonia in Highlands children is required to enable a rational choice of routine antibiotic therapy and to plan further research on vaccination against pneumonia.