Effect of beta-adrenergic blockade on plasma lactate concentration during exercise at high altitude

When unacclimatized lowlanders exercise at high altitude, blood lactate concentration rises higher than at sea level, but lactate accumulation is attenuated after acclimatization. These responses could result from the effects of acute and chronic hypoxia on beta-adrenergic stimulation. In this investigation, the effects of beta-adrenergic blockade on blood lactate and other metabolites were studied in lowland residents during 30 min of steady-state exercise at sea level and on days 3, 8, and 20 of residence at 4300 m. Starting 3 days before ascent and through day 15 at high altitude, six men received propranolol (80 mg three times daily) and six received placebo. Plasma lactate accumulation was reduced in propranolol- but not placebo-treated subjects during exercise on day 3 at high altitude compared to sea-level exercise of the same percentage maximal oxygen uptake (VO2max). Plasma lactate accumulation exercise on day 20 at high altitude was reduced in both placebo- and propranolol-treated subjects compared to exercise of the same percentage VO2max performed at sea level. The blunted lactate accumulation during exercise on day 20 at high altitude was associated with reduced muscle glycogen utilization. Thus, increased plasma lactate accumulation in unacclimatized lowlanders exercising at high altitude appears to be due to increased beta-adrenergic stimulation. However, acclimatization-induced changes in muscle glycogen utilization and plasma lactate accumulation are not adaptations to chronically increased beta-adrenergic activity.     

On the nature of dilute aqueous cholesterol suspensions

Cholesterol is commonly supposed to form a micelle in aqueous solution. We have reassessed this finding using a variety of techniques. Centrifugation sedimented cholesterol at all concentrations above 10(-8) M. Density gradient analysis of more concentrated solutions revealed two bands whose densities corresponded to crystalline anhydrous cholesterol and crystalline cholesterol monohydrate. The monohydrate was characterized by light microscopy and phase transition. This band is also claimed to contain micelles, but no enhancement of perylene or diphenylhexatriene fluorescence could be detected. Some crystals of monohydrate could pass through 0.7-microns filters but not through 1.5-nm filters. Crystals of monohydrate were detected on the latter filters when solutions with cholesterol concentrations as low as 2.6 X 10(-8) M were filtered. Thus, under all conditions where micelles might be expected, we have detected micro-crystals of cholesterol monohydrate and we can find no independent evidence to support the existence of a cholesterol micelle.     

Sterols of three lichen species: Lobaria pulmonaria, Lobaria Scrobiculata and Usnea Longissima

Sterols were extracted from the lichens Lobaria pulmonaria, Lobaria scrobiculata and Usnea longissima with chloroform-methanol (2:1) (solvent-extractable fraction) followed by saponification of the residual lichen material to give a tightly-bound sterol fraction. The compounds were principally ergosterol, episterol, fecosterol and lichesterol with minor quantities of C₁₇, C₂₈ and C₂₉ monoenes and dienes of the phytosterol type.     

Dicarboxylic Amino Acid Influx across Brush Border of Rabbit Ileum : Effects of amino acid charge on the sodium-amino acid interaction

Glutamate and aspartate influxes across the brush border of rabbit intestine are saturable processes that are subject to competitive inhibition and are markedly influenced by the Na concentration in the mucosal solution. Lowering the Na concentration increases the amino acid concentration needed to elicit a half-maximal influx but does not significantly affect the maximal influx. The interaction between Na and anionic amino acid influx can be described by the same kinetic model that has been applied to the influxes of neutral amino acids and lysine. Comparison of the kinetic parameters for anionic, neutral, and cationic amino acids suggests that amino acid charge influences (a) the stability of the binary (amino acid-site) complex and (b) the affinity of this binary complex for the subsequent binding of Na. A mechanistic interpretation of these interactions is proposed.     

Procedure

This piece examines the diagnostic procedures for breast cancer from the patient’s point of view, trying to establish the importance of communication and reassurance, while showing how the absence of these can lead to greater distress than necessitated.     

Phylogeny of mosquitoes of tribe Culicini (Diptera: Culicidae) based on morphological diversity

Harbach, R. E., Kitching, I. J., Culverwell, C. L., Dubois, J. & Linton, Y.‐M. (2012). Phylogeny of mosquitoes of tribe Culicini (Diptera: Culicidae) based on morphological diversity. —Zoologica Scripta, 41, 499–514. Relationships among taxa of the mosquito tribe Culicini are explored using 169 morphological characters from 86 exemplar species representing the four genera and 26 subgenera of Culicini, most species groups and subgroups of subgenus Culex and an outgroup of five species from five other tribes. We analysed the data set, with multistate characters treated as unordered, under implied weights with values of K ranging from 1 to 20, implemented by TNT. Each analysis, except K = 4, produced a single most parsimonious (fittest) cladogram (MPC). The topology of the ingroup was identical for K = 6–11, whereas the MPCs for K = 14–20 differed only in the position of a single species, which occupied the same position in the K = 16 and K = 6–11 topologies. The K = 9 and K = 16 trees were given further consideration. In both these cladograms, Lutzia is sister to a clade comprising genera Culex, Deinocerites and Galindomyia. The two topologies have 13 clades in common, but their arrangements differ primarily because of Culex (Culex) duttoni acting as a ‘rogue’ taxon. We evaluated the effect of removing this species from the K = 9 and K = 16 analyses and chose the refined K = 9 topology as the best hypothesis of relationships within Culicini. Genus Culex is not monophyletic because it includes Deinocerites and Galindomyia as derived members of the New World subgenera. With the exception of subgenera Culex, Eumelanomyia and Neoculex, there is strong support for the monophyly of all genera and subgenera. Subgenus Culex would be monophyletic were four other subgenera included and three other taxa (the Afrotropical Cx. duttoni, Neotropical Cx. apicinus and the Australasian Atriceps Group) excluded.     

Using shared goal setting to improve access and equity: a mixed methods study of the Good Goals intervention in children's occupational therapy

ABSTRACT: BACKGROUND: Access and equity in children's therapy services may be improved by directing clinicians' use of resources toward specific goals that are important to patients. A practice-change intervention (titled 'Good Goals') was designed to achieve this. This study investigated uptake, adoption, and possible effects of at intervention in children's occupational therapy services. METHODS: Mixed methods case studies (n = 3 services, including 46 therapists and 558 children) were conducted. The intervention was delivered over 25 weeks through face-to-face training, team workbooks, and 'tools for change'. Data were collected before, during, and after the intervention on a range of factors using interviews, a focus group, case note analysis, routine data, document analysis, and researchers' observations. RESULTS: Factors related to uptake and adoptions were: mode of intervention delivery, competing demands on therapists' time, and leadership by service manager. Service managers and therapists reported that the intervention: helped therapists establish a shared rationale for clinical decisions; increased clarity in service provision; and improved interactions with families and schools. During the study period, therapists' behaviours changed: identifying goals, odds ratio 2.4 (95% CI 1.5 to 3.8); agreeing goals, 3.5 (2.4 to 5.1); evaluating progress, 2.0 (1.1 to 3.5). Children's LoT decreased by two months [95% CI [MINUS SIGN]8 to +4 months] across the services. Cost per therapist trained ranged from [POUND SIGN]1,003 to [POUND SIGN]1,277, depending upon service size and therapists' salary bands. CONCLUSIONS: Good Goals is a promising quality improvement intervention that can be delivered and adopted in practice and may have benefits. Further research is required to evaluate its: (i) impact on patient outcomes, effectiveness, cost-effectiveness, and (ii) transferability to other clinical contexts.