Effect of site of lactate infusion on regional lactate exchange in pigs.

BACKGROUND: The rate of extra-hepatic lactate production and the route of influx of lactate to the liver may influence both hepatic and extra-hepatic lactate exchange. We assessed the dose-response of hepatic and extra-hepatic lactate exchange during portal and central venous lactate infusion. METHODS: Eighteen pigs randomly received either portal (n=5) or central venous (n=7) lactate infusion or saline (n=6). Sodium lactate was infused at 33, 66, 99, and 133 µmol kg⁻¹ min⁻¹ for 20 min each. Systemic and regional abdominal blood flows and plasma lactate were measured at 20 min intervals until 1 h post-infusion, and regional lactate exchange was calculated (area under lactate uptake-time curve). RESULTS: Total hepatic lactate uptake [median (95% confidence interval)] during the experimental protocol (140 min) was higher during portal [8198 (5487-12 798) µmol kg(-1)] than during central venous lactate infusion [4530 (3903-5514) µmol kg⁻¹, P<0.05]. At a similar hepatic lactate delivery (∼400 µmol kg⁻¹ min⁻¹), hepatic lactate uptake [mean and standard deviation (sd)] was higher during portal [118 (sd 55) µmol kg⁻¹ min⁻¹] than during central venous lactate infusion [44 (12) µmol kg⁻¹ min⁻¹, P < 0.05]. Time courses of arterial lactate concentrations and lactate uptake at other measured regions were similar in both groups. CONCLUSIONS: Higher hepatic lactate uptake during portal compared with central venous lactate infusion at a similar total hepatic lactate influx underlines the role of portal vein lactate concentration in total hepatic lactate uptake capacity. Arterial lactate concentration does not depend on the site of lactate infusion. At higher arterial lactate concentrations, all regions participated in lactate uptake.

Nuclear and mitochondrial DNA reveals isolation of imperilled grey nurse shark populations (Carcharias taurus).

Loss of sharks and other upper-trophic marine predators has sparked worldwide concern for the stability of ocean ecosystems. The grey nurse (ragged-tooth or sand tiger) shark (Carcharias taurus) is Vulnerable on a global scale, Critically Endangered in Australia and presumed extinct in parts of its historical range. We used 193 muscle and fin samples collected from six extant populations to assess global mtDNA and microsatellite diversity and the degree of global population genetic structure. Control region mtDNA diversity was low in every population, and two populations (eastern Australia and Japan) contained only a single mtDNA haplotype. Genetic signatures of recent losses of genetic variation were not yet apparent at microsatellite loci, indicating that this low mtDNA variation is not a result of anthropogenic population declines. Population differentiation was substantial between each population pair except Brazil and South Africa, F(ST) values ranged from 0.050 to 0.699 and 0.100 to 1.00 for microsatellite and mitochondrial data respectively. Bayesian analysis clearly partitioned individuals into five of the populations from which they were sampled. Our data imply a low frequency of immigrant exchange among each of these regions and we suggest that each be recognized as a distinct evolutionary significant unit. In contrast to pelagic species such as whale shark and white shark that may cross ocean basins and where cooperative international efforts are necessary for conservation, grey nurse shark, like many coastal species, need to be managed regionally.

Two Novel Microsporidia in Skeletal Muscle of Pike-Perch Sander lucioperca and Burbot Lota lota in Finland.

Two new species of Microsporidia were recognized in skeletal muscle of freshwater fishes from Finland. Myosporidium spraguei n. sp. from pike-perch Sander lucioperca occurred as mature spores within sporophorous vesicles (SPVs) within a xenoma. The ovoid spores were 3.8 µm long and 2.4 µm wide, based on transmission electron micrographs (TEM). The exospore and endospore were equally thick, the nucleus was monokaryotic and the polar filament was isofilar with 12 coils in a single rank, entirely adjacent to the prominent posterior vacuole. Small subunit (SSU) rDNA sequence confirmed the presence of M. spraguei n. sp. in burbot Lota lota . The second species, Microsporidium luciopercae n. sp., also from pike-perch, occurred within SPVs that occupied only a fraction of the volume of the otherwise intact myocyte; no xenoma was produced. Myocyte degeneration and necrosis occurred as mature spores dispersed into direct contact with the sarcoplasm. The ovoid spores were 4.6 µm long and 2.8 µm wide (based on TEM); they were monokaryotic and the polar filament was isofilar with 25 coils in a single rank in the posterior of the spore. The exospore was relatively thin with an irregular profile. Neither infection elicited an inflammatory response, although degenerate spores were observed within host cells, suggesting phagocytosis. Phylogenetic analysis of SSU sequences placed both organisms on distinct clades within the Marinosporidia.

Locality and habitus: the origins of sickness absence practices.

This article aims to understanding the differences observed in the sickness absence practices of three municipal work organisations. Sickness absence figures were contextualised with a two-level analysis. The working communities were studied with the material collected for the study from documents, interviews, and a postal questionnaire survey on psychosocial working conditions. At the locality level the quality and quantity of economic, social, and cultural capitals were assessed. On the basis of this material, community diagnoses of the three localities are presented. The relationship of the way of life and being ill in the locality to the sickness absences among the employees of the municipality is discussed using the concepts of 'field', 'habitus', 'practice' and 'capital' as presented by Bourdieu. Sickness absence practices seem to be connected to the relative dominance of social classes in the locality. We conclude that the sickness absence practice of the municipal working community is an expression of the sickness absence habitus which is deeply rooted in the social history of the locality and in the health-related behaviour of the residents. In being not too structuralistic and not too relativistic, Bourdieu's theory helps us to understand the reality of the sickness absences; they can only be influenced marginally and temporarily by simple intervention measures in the work-places. More lasting changes in the level of sickness absences would require profound changes in the working community and-ultimately-in the whole locality.

Efficacy of three prevention strategies against legionella in cooling water systems.

The efficacy of three different prevention strategies on legionella in cooling systems was studied. The strategies were as follows: (1) water temperature was lowered; (2) water quality was improved; or (3) the system as disinfected with polyhexamethylene biguanidechloride (PHMB) biocide or with 2-bromo-2-nitropropane-1,3-diol (BNPD) biocide. Lowering of water temperature was the most effective method to reduce the concentration of legionella in cooling systems. Improving of water quality resulted in a transitory disinfection effect. The additions of PHMB or BNPD decreased the concentrations of both legionella and heterotrophic bacteria in cooling water. The effect of biocides, however, lasted at the most only a few months. If possible, lowering water temperature and improving the water quality should be the primary practices for controlling bacterial growth in cooling systems. Regular biocide treatments should be incorporated into the maintenance procedures if technical improvements cannot be done or if their efficiency is too low.

Growth of Legionella and other heterotrophic bacteria in a circulating cooling water system exposed to ultraviolet irradiation.

The effect of ultraviolet irradiation on the growth and occurrence of legionella and other heterotrophic bacteria in a circulating cooling water system was studied. Water of the reservoir was circulated once in 28 h through a side-stream open channel u.v. radiator consisting of two lamps. Viable counts of legionellas and heterotrophic bacteria in water immediately after the u.v. treatment were 0-12 and 0.7-1.2% of those in the reservoir, respectively. U.v. irradiation increased the concentration of easily assimilable organic carbon. In the u.v. irradiated water samples incubated in the laboratory the viable counts of heterotrophic bacteria reached the counts in reservoir water within 5 d. The increase in viable counts was mainly due to reactivation of bacterial cells damaged by u.v. light, not because of bacterial multiplication. Despite u.v. irradiation the bacterial numbers in the reservoir water, including legionellas, did not decrease during the experimental period of 33 d. The main growth of bacteria in the reservoir occurred in biofilm and sediment, which were never exposed to u.v. irradiation.