High Trapped Fields in C-doped MgB2 Bulk Superconductors Fabricated by Infiltration and Growth Process.

The grain boundaries in superconducting MgB2 are known to form effective magnetic flux pinning sites and, consequently, bulk MgB2 containing a fine-grain microstructure fabricated from nanoscale Mg and B precursor powders exhibits good magnetic field-trapping performance below 20 K. We report here that the trapped field of MgB2 bulk superconductors fabricated by an infiltration and growth process to yield a dense, pore-free microstructure, can be enhanced significantly by carbon-doping, which increases intra-band scattering within the superconducting grains. A maximum trapped field of 4.15 T has been measured at 7.5 K at the centre of a five-sample stack of Mg(B1-xiCxi)2 bulk superconductors processed by infiltration and growth, which not only represents a ~40% increase in trapped field observed compared to undoped bulk MgB2, but also is the highest trapped field reported to date in MgB2 samples processed under ambient pressure. The trapped field is observed to decay at a rate of <2%/day at 10 K, which suggests that bulk MgB2 superconductors fabricated using the infiltration and growth technique can be used potentially to generate stable, high magnetic fields for a variety of engineering applications.

Expression of dihydropyridine receptor (Ca2+ channel) and calsequestrin genes in the myocardium of patients with end-stage heart failure.

Cytoplasmic free calcium ions (Ca2+) play a central role in excitation-contraction coupling of cardiac muscle. Abnormal Ca2+ handling has been implicated in systolic and diastolic dysfunction in patients with end-stage heart failure. The current study tests the hypothesis that expression of genes encoding proteins regulating myocardial Ca2+ homeostasis is altered in human heart failure. We analyzed RNA isolated from the left ventricular (LV) myocardium of 30 cardiac transplant recipients with end-stage heart failure (HF) and five organ donors (normal control), using cDNA probes specific for the cardiac dihydropyridine (DHP) receptor (the alpha 1 subunit of the DHP-sensitive Ca2+ channel) and cardiac calsequestrin of sarcoplasmic reticulum (SR). In addition, abundance of DHP binding sites was assessed by ligand binding techniques (n = 6 each for the patients and normal controls). There was no difference in the level of cardiac calsequestrin mRNA between the HF patients and normal controls. In contrast, the level of mRNA encoding the DHP receptor was decreased by 47% (P less than 0.001) in the LV myocardium from the patients with HF compared to the normal controls. The number of DHP binding sites was decreased by 35-48%. As reported previously, expression of the SR Ca(2+)-ATPase mRNA was also diminished by 50% (P less than 0.001) in the HF group. These data suggest that expression of the genes encoding the cardiac DHP receptor and SR Ca(2+)-ATPase is reduced in the LV myocardium from patients with HF. Altered expression of these genes may be related to abnormal Ca2+ handling in the failing myocardium, contributing to LV systolic and diastolic dysfunction in patients with end-stage heart failure.

The minimum effective doses of pethidine and doxapram in the treatment of post-anaesthetic shivering.

This study was designed to find the minimum effective doses of doxapram and pethidine to stop post-anaesthetic shivering. Two hundred and twenty healthy patients who shivered following routine surgery were allocated randomly to receive one of 10 doses of doxapram (0.18, 0.23, 0.29, 0.35, 0.41, 0.47, 0.7, 0.93, 1.17 and 1.4 mg.kg-1), one of five doses of pethidine (0.12, 0.18, 0.23, 0.29 and 0.35 mg.kg-1) or saline. Probit analysis demonstrated that the number of patients who stopped shivering with doxapram was independent of the amount of drug given in this dose range. The lowest dose of doxapram (0.18 mg.kg-1) was significantly more effective than placebo (p < 0.01). For pethidine there was a dose-dependent effect on shivering to a maximum of 95% of patients successfully treated with 0.35 mg.kg-1. We conclude that 0.35 mg.kg-1 of pethidine is the minimum dose required to treat post-anaesthetic shivering effectively. We also conclude that 0.18 mg.kg-1 of doxapram is as effective as 1.4 mg.kg-1 in the treatment of post-anaesthetic shivering. Further study is required to find the minimum effective dose of doxapram.

A comparison of diclofenac with ketorolac for pain relief after knee arthroscopy.

We performed a double-blind controlled trial to compare the analgesic effect of two nonsteroidal anti-inflammatory drugs. We compared rectal diclofenac 100 mg given 1 h before induction of anaesthesia with intravenous ketorolac 10 mg given immediately before anaesthesia in 40 patients undergoing arthroscopy of the knee as day cases. A visual analogue scale was used to assess pain prior to discharge. Pain, analgesic consumption, sleep disturbance and restriction of activities were recorded by telephone enquiry 24 h after surgery. There was no difference in the pain parameters, sleep disturbance, or restriction of activity between groups. We suggest that ketorolac 10 mg intravenously and diclofenac 100 mg rectally provide comparable postoperative analgesia in the first 24 h after arthroscopy of the knee.

Analgesia after caesarean section. The use of rectal diclofenac as an adjunct to spinal morphine.

A double-blind placebo-controlled study was performed to assess the analgesic effect of rectal sodium diclofenac 100 mg after Caesarean section using subarachnoid hyperbaric bupivacaine 0.5% and morphine 0.2 mg. During the 48 h follow-up period, both placebo and diclofenac groups had comparable analgesia as measured by visual analogue scores (VAS) at rest and on movement. However, diclofenac prolonged the mean time to first analgesia by more than 5 h from 13 h 45 min in the placebo group to 18 h 58 min (p < 0.03). The incidence of side effects (nausea, vomiting, itching, excessive lochia loss and the need for additional analgesia) were comparable in each group.

Local anaesthesia for cannulation. Has practice changed?

A questionnaire study was undertaken to assess the influence of recently published, simple and conclusive research on the practice of anaesthetists in four centres. The research had clearly demonstrated the benefit of subcutaneous infiltration of local anaesthetic in reducing the pain of intravenous cannulation. Of the 81% who responded, 71% were aware of the research; 43% of these anaesthetists had altered their clinical practice as a result of the research and 73% used local anaesthesia for cannulae of 18 gauge or less, compared with only 46% of those who were unaware of the research. Practice comparisons were made between centres and grades of anaesthetist. Senior house officers were significantly less likely to be aware of the research than other grades. Anomalies were identified between the apparent awareness of the research and routine practice agreeing with the study findings. The value of research and the incorporation of clinical findings into everyday practice is discussed.

Prevalência de asma em escolares de 13-14 anos de Brasília - DF. Comparação entre 1996 e 2002, por grupos socioeconômicos / Asthma prevalence in 13-14-year-old schoolchildren from Brasília - DF. Comparison between 1996 and 2002 data by socioeconomic status

Objetivos: Determinar a prevalência da asma e seus sintomas em escolares de 13-14 anos de idade, de Brasília-DF. Avaliar suas tendências, comparando os dados de 2002 com os de 1996. Comparar as taxas de prevalência da asma entre diferentes grupos socioeconômicos. Métodos: Dois estudos de corte transversal foram realizados com intervalo de seis anos, usando o questionário escrito do protocolo ISAAC (Fases I e III). Nesta pesquisa, 39 escolas públicas e privadas foram escolhidas aleatoriamente, em oito regiões administrativas de Brasília, que foram divididas em três grupos, segundo as condições socioeconômicas da população. Resultados: Foram obtidos 3.009 questionários, sendo 80% de alunos de escolas públicas, com 53,5 % do sexo feminino. Comparando com dados de 1996, não houve aumento significativo da prevalência de asma diagnosticada (de 13,8 para 14,8%) e nem de asma atual (de 19,5 para 19,7%). A prevalência de asma diagnosticada foi significativamente maior nas escolas privadas do que nas escolas públicas (17,8% x 14,1 %), assim como nas populações de melhor nível socioeconômico (17,7% x 11,5%). Comparando os grupos socioeconômicos, não houve diferença significativa entre os dois estudos. Houve relato concomitante de rinite alérgica em 37,4% dos asmáticos e de eczema atópico em 24,7%. Apenas 53 (1,7%) reportaram a ocorrência das três patologias simultaneamente. Conclusão: A prevalência de asma diagnosticada, em crianças de 13 a 14 anos de idade do DF, não apresentou aumento significativo em um período de seis anos e foi significativamente maior nas crianças de escolas privadas e de nível socioeconômico mais elevado.