Intracellular carbonic anhydrase contributes to the red blood cell adrenergic response in rainbow trout Oncorhynchus mykiss

In many teleost fish, catecholamines activate a red blood cell (RBC) Na(+)/H(+) exchanger (βNHE), raising RBC intracellular pH to protect haemoglobin-O(2) loading. The present study tested the hypothesis that RBC intracellular carbonic anhydrase (CA) contributes to this adrenergic response. The pH of rainbow trout (Oncorhynchus mykiss) blood was monitored continuously in vitro using blood flowing in a semi-closed loop or in vivo using an extracorporeal circulation. Addition or injection of isoproterenol activated the βNHE, causing blood pH to fall (in vitro ΔpH=-0.28±0.03 pH units, N=16; in vivo, -0.12±0.02 pH units, N=6). Both in vitro and in vivo, inhibition of RBC CA by acetazolamide significantly decreased the magnitude of the adrenergic response (in vitro, ΔpH=-0.22±0.02 pH units, N=16; in vivo, -0.02±0.01 pH units, N=6) as well as the rate of recovery of blood pH following the adrenergic response. These results support the hypothesis that RBC intracellular CA plays an important role in the RBC adrenergic response of rainbow trout, and fuel speculation that interspecific differences in RBC CA activity are associated with the magnitude of the RBC adrenergic response.     

Modified composite or conventional glass ionomer for band cementation? A comparative clinical trial.

The time to first failure, the position of band failure at deband, and the change in enamel white spot lesions of teeth bonded with a modified composite or a conventional glass ionomer were compared in a randomized half-mouth trial over the full course of orthodontic treatment. One hundred forty band pairs were cemented in 98 subjects. Overall band failure rates of 5% and 2.8% were recorded for the modified composite and the conventional glass ionomer, respectively, with no significant difference found between their times to first band failure. At the end-of-treatment deband, the position of band failure was predominantly at the enamel-cement interface for the modified composite and at the band-cement interface for the conventional glass ionomer (P <.001). A comparison of changes in mean enamel white spot lesion scores during treatment did not reveal significant differences between the cement groups (P =.16).     

Body size of young Australians aged five to 16 years

In 1983-1984, 4578 Perth primary and secondary schoolchildren were studied. The selected sample was broadly representative of the ethnic groups that make up the Perth population and of the different social ranks within that population. The age, sex, weight, height, country of birth of the child and the parents, and occupation of the father were recorded for each subject. Weight, height and body mass index (BMI) increased with age. Age and sex were the most important determinants of body size. However, children of lower social rank and those with a southern European background were over-represented among the overweight children (greater than the 90th centile for BMI), particularly in adolescence. Children with an Asian background who were 11 years of age and younger were over-represented among the underweight children (less than or equal to the 10th centile for BMI). Results from this study indicate a continuing, though small (1.5 cm to 1.6 cm), secular increase in height over the past 13 to 14 years.     

Spatiotemporal transition to conduction block in canine ventricle

Interruption of periodic wave propagation by the nucleation and subsequent disintegration of spiral waves is thought to mediate the transition from normal sinus rhythm to ventricular fibrillation. This sequence of events may be precipitated by a period doubling bifurcation, manifest as a beat-to-beat alternation, or alternans, of cardiac action potential duration and conduction velocity. How alternans causes the local conduction block required for initiation of spiral wave reentry remains unclear, however. In the present study, a mechanism for conduction block was derived from experimental studies in linear strands of cardiac tissue and from computer simulations in ionic and coupled maps models of homogeneous one-dimensional fibers. In both the experiments and the computer models, rapid periodic pacing induced marked spatiotemporal heterogeneity of cellular electrical properties, culminating in paroxysmal conduction block. These behaviors resulted from a nonuniform distribution of action potential duration alternans, secondary to alternans of conduction velocity. This link between period doubling bifurcations of cellular electrical properties and conduction block may provide a generic mechanism for the onset of tachycardia and fibrillation.     

Rapid protein-based assays for the diagnosis of T-B+ severe combined immunodeficiency

The severe combined immunodeficiencies (SCID) are a heterogeneous group of conditions arising from a variety of molecular defects. The X-linked form of SCID (X-SCID) is caused by defects in the common gamma chain (gammac), and is characterized by a T-B+NK- immunophenotype. This lymphocyte profile is seen in an autosomal recessive form of SCID caused by mutations in the JAK3 molecule. Thus, X-SCID and JAK3-deficient SCID are clinically and immunologically indistinguishable. Knowledge of the precise molecular defect is essential for antenatal diagnosis, carrier testing and for treatment using somatic gene therapy. To identify the molecular defect in children presenting with a T-B+NK- form of SCID, we have developed rapid assays based on flow cytometric analysis of gammac, immunoblotting for JAK3 and gammac, and detection of interleukin-2 (IL-2)-induced tyrosine phosphorylation of JAK3. Sixteen T-B+NK- SCID patients from 15 families were examined. Nine had no detectable gammac, four had abnormal gammac expression and no IL-2-induced JAK3 tyrosine phosphorylation, and one had normal gammac expression but no IL-2-induced JAK3 tyrosine phosphorylation, although JAK3 was present. All these patients had mutations identified in their gammac gene. Two patients exhibited normal gammac expression, but JAK3 was not detected by immunoblotting and these patients were confirmed as having JAK3 gene mutations. Thus, these protein-based assays have led to rapid molecular diagnoses in T-B+ SCID that have subsequently been confirmed by genetic analysis.     

Nurses and Internet health information: a questionnaire survey

AIM: This paper is a report of a study to identify the extent of postgraduate nursing students' information literacy skills in relation to electronic media and health information and barriers to accessing this information. BACKGROUND: The Internet is a key source of information for a significant group of patients. However, there is evidence of quality issues with some Internet health information sites. Nurses need to be aware of the range and quality of online health information so as to assist patients and families to locate and evaluate relevant and current information. METHOD: A questionnaire designed to collect quantitative and qualitative data was posted to a convenience sample of all students enrolled in a postgraduate nursing programme in December 2005. The response rate was 55.1% or 123 responses. RESULTS: Most respondents had Internet access at home and work and believed that access to online health information resources had improved their practice. However, some had difficulties in accessing computers at work and insufficient time to search for online health information. Concern was expressed about the quality of online information, but the majority of respondents did not assess patient use. Frequent users of online resources were more likely to assess patient use. CONCLUSION: The development of nursing competencies in accessing and using online resources is a key precursor to supporting patients and families' use of the medium. Access to Internet resources at work, along with training and time for searching, is necessary for the development of skills enabling effective use of information technology.     

Treatment of normal individuals with granulocyte-colony-stimulating factor: donor experiences and the effects on peripheral blood CD34+ cell counts and on the collection of peripheral blood stem cells

BACKGROUND: Granulocyte-colony-stimulating factor (G-CSF) has been used in patients to increase the level of circulating hematopoietic progenitors. Although G-CSF has been administered to some healthy individuals, the kinetics of mobilization of peripheral blood stem cells (PBSCs), the optimum dose schedule and the incidence and nature of adverse reactions in normal individuals are not completely defined. STUDY DESIGN AND METHODS: Normal individuals (n = 102) who received G- CSF for 5 or 10 days at doses of 2, 5, 7.5, or 10 micrograms per kg per day were studied. The subjects were observed for symptoms and physical changes, and blood samples were obtained for a variety of laboratory tests. After 5 or 10 days of G-CSF treatment, PBSCs were collected by apheresis and analyzed. RESULTS: Overall, 89 percent of the individuals completed the 5-day treatment protocol and 88 percent completed the 10- day protocol without modification of the dose of G-CSF administered. Ninety percent of donors experienced some side effect of G-CSF. The most frequent effects noted were bone pain (83%), headache (39%), body aches (23%), fatigue (14%), and nausea and/or vomiting (12%). The dose of G-CSF administered directly affected the proportion of people with bone pain (p = 0.025) or body aches (p = 0.045) or who were feeling hot or having night sweats (p = 0.02) or taking analgesics (p = 0.01). With the 5-day dose schedule, several changes in serum chemistries occurred, including increases in alkaline phosphatase (p = 0.001), alanine aminotransferase (p = 0.0013), lactate dehydrogenase (p = 0.0001), and sodium (p = 0.0001). Decreases occurred in glucose (p = 0.045), potassium (p = 0.0004), bilirubin (p = 0.001), and blood urea nitrogen (p = 0.0017). In donors who received G-CSF for 5 days, the absolute neutrophil count was increased after one G-CSF dose, and it reached a maximum on Day 6, as did the number of CD34+ cells (64.6 +/? 55.9 × 10(6) cells/L). In those same donors, the platelet count after apheresis on Day 6 was 32 +/? 13 percent lower than pretreatment values (250 +/? 42 × 10(9) cells/L). In donors receiving G-CSF for 10 days, the neutrophil count reached a maximum on Day 8, but the number of CD34+ cells peaked on Day 6 (58.3 +/? 52.1 × 10(5) cells/L) and then declined. The platelet count decreased from pretreatment values by 28 +/? 12 percent prior to apheresis on Day 11. When individuals were treated for 5 days with G-CSF, the quantity of CD34+ cells collected was directly related to the G-CSF dose. When 5 micrograms per kg per day was given, 2.80 +/? 1.81 × 10(8) cells were collected, compared with collection of 4.67 +/? 3.11 × 10(8) cells when 10 micrograms per kg per day was given (p = 0.04). More important, PBSCs collected after 10 days of G-CSF administration (5 micrograms/kg/day) had significantly fewer CD34+ cells (0.82 +/? 0.37 × 10(8) cells, p = 0.01) than did PBSCs collected after 5 days of G-CSF (5 micrograms/kg/day). CONCLUSION: Most normal donors receiving G-CSF experience side effects, but these are mild to moderate in degree. Some alterations in blood chemistries occur, but none were clinically serious. Because of the symptoms associated with G-CSF, these individuals must be monitored closely. The treatment of normal donors with G-CSF for more than 5 days significantly decreased the number of circulating CD34+ cells and the quantity collected by apheresis.