HIV and measures to control infection in general practice.

OBJECTIVE--To assess the impact of HIV on procedures to control infection in general practices. DESIGN--A postal questionnaire survey. SETTING--General practices throughout Britain. SUBJECTS--5359 General practitioners, 3429 (63.9%) of whom returned the questionnaire. MAIN OUTCOME MEASURE--Response to questionnaire on knowledge about HIV and policies for controlling infection. RESULTS--Most doctors (2018) had started to wear gloves when taking blood. Almost half (1510) had not resheathed needles previously but a further 776 had adopted this policy because of HIV. Over half of the doctors did not know or were unsure about the risk of infection from needlestick injuries, and 1759 had no practice policy for controlling infection. CONCLUSIONS--Many doctors are uncertain about measures to control infection in general practice. More information and advice are needed to help doctors develop policies to protect patients and staff.     

Comparison of two scores for allocating resources to doctors in deprived areas.

Current proposals in the general practitioner contract include additional payments to doctors working among deprived populations. The underprivileged area score will be used to identify local authority wards with the greatest levels of deprivation, thus acting as the basis for distributing considerable resources. Two methods of identifying deprived populations--the underprivileged area score and the material deprivation score--were compared to determine whether they result in similar allocation of resources to regions. Financial allocations to regions based on figures derived from the contract differed considerably if the material deprivation score was used instead of the underprivileged area score: Northern and Mersey regions gained over 50% of their allocation whereas East Anglia, Oxford, and South West Thames regions lost more than 30% of theirs. Such differences have considerable implications for doctors working among deprived populations as up to 60m pounds each year might be distributed by these payments.     

Engineering organ perfusion protocols: NMR analysis of hepatocyte isolation from perfused rat liver

The development and use of an extracorporeal liver support device depends upon the isolation of a large number of viable, functioning hepatocytes from whole or partial livers. Current practice, however, produces nonoptimal yields, given that a large percentage of hepatocytes initially present are not successfully isolated. The normal hepatocyte isolation protocol consists of sequential perfusion with calcium chelating and collagenase buffers, and then separation of viable hepatocytes from non-viable and nonparenchymal cells, usually on the basis of cell density. In order to improve understanding regarding the metabolic and perfusion state of the liver during this perfusion protocol, ATP, pH, and tissue perfusion were evaluated using nuclear magnetic resonance (NMR). Perfusion with calcium chelating buffer was found to have minimal effect on the metabolic and perfusion parameters, whereas subsequent perfusion with collagenase buffer produced large declines in ATP, pH, and homogeneity of perfusion within 3 min. Perfusion with calcium-chelating buffer alone, or perfusion with calcium chelating buffer followed by a short period of ischemia to mimic the perfusion disruption of collagenase, did not produce the same decline in metabolic parameters. This NMR data suggested that enhancing the early perfusion and penetration of collagenase or prolonging the nontoxic calcium-chelation step may improve the yield and/or functionality of isolated cells. Therefore, several altered perfusion protocols were evaluated in terms of yield of viable parenchymal hepatocytes and hepatocyte albumin production. Although increasing the perfusion flow rate and initial perfusion with inactive (cold) collagenase did not produce significant improvements when compared with the control protocol (control cell yield 226 +/- 42 x 10(6) viable hepatocytes for 10- to 14-week-old female Lewis rat), prolonging and enhancing the calcium-chelating perfusion step or increasing the collagenase concentration did yield a significantly great number of viable parenchymal hepatocytes (393 +/- 44 and 328 +/- 39 x 10(6) viable hepatocytes, respectively) with no change in albumin production per seeded viable cell. (c) 1994 John Wiley & Sons, Inc.     

Nucleotide variation at the hypervariable esterase 6 isozyme locus of Drosophila simulans

Esterase 6 (Est-6/EST6) is polymorphic in both Drosophila melanogaster and D. simulans for two common allozyme forms, as well as for several other less common variants. Parallel latitudinal clines in the frequencies of the common EST6-F and EST6-S allozymes in these species have previously been interpreted in terms of a shared amino acid polymorphism that distinguishes the two variants and is subject to selection. Here we compare the sequences of four D. simulans Est-6 isolates and show that overall estimates of nucleotide heterozygosity in both coding and 5' flanking regions are more than threefold higher than those obtained previously for this gene in D. melanogaster. Nevertheless, the ratio of replacement to exon silent-site polymorphism in D. simulans is less than the ratio of replacement to silent divergence between D. simulans and D. melanogaster, which could be the result of increased efficiency of selection against replacement polymorphisms in D. simulans or to divergent selection between the two species. We also find that the amino acid polymorphisms separating EST6- F and EST6-S in D. simulans are not the same as those that separate these allozymes in D. melanogaster, implying that the shared clines do not reflect shared molecular targets for selection. All comparisons within and between the two species reveal a remarkable paucity of variation in a stretch of nearly 400 bp immediately 5' of the gene, indicative of strong selective constraint to retain essential aspects of Est-6 promoter function.      

Effect of ethephon and daminozide on the respiration of isolated leaf cells

A combined foliar application of ethephon (2-chloroethylphosphonic acid) at 0.8 kg/ha and daminozide (butanedioic acid mono (2,2 dimethylhydrazide) at 3.2 kg/ha inhibited the vegetative growth of Black Valentine bean (Phaseolus vulgaris L.) without the leaf chlorosis and necrosis caused by ethephon alone. This antagonistic interaction was further evaluated by examining the effect of ethephon and daminozide on respiration and lipid synthesis of isolated leaf cells. Ethephon (1.0 mM) promoted¹⁴CO₂ evolution from cells incubated with¹⁴C-glucose for 14 h by approximately 75%. Characterization of this response with Black Valentine bean mitochondria indicated that the observed stimulation could not be attributed to the existence of a major cyanide insensitive pathway or the possibility of ethephon acting as an uncoupler, which supports the view that ethephon (or ethylene) acts in the cytosol rather than in mitochondria. Daminozide at 30.0 and 60.0 mM inhibited¹⁴CO₂ evolution of isolated cells by 30 and 70%, respectively. Ethephon in combination with daminozide (1.0+60 mM) resulted in a 32% inhibition of respiration. Daminozide (60.0 mM) inhibited the incorporation of¹⁴C-glucose into chloroform-methanol soluble products by 47%, but did not affect the incorporation of¹⁴C-acetate. The results suggest that daminozide may reduce or overcome any stimulatory effect of ethephon on respiration and support an active inhibitory site for daminozide in mitochondria.     

Ontogeny and distribution of the murine B cell Fc gamma RII.

The distribution and expression of the IgG FcRII (Fc gamma RII) on normal murine B cells was examined. Using multicolor flow cytometry, spleens from neonatal mice of increasing age and adult bone marrow were analyzed for expression of the Fc gamma RII. In addition, B cells from peripheral lymphoid organs, as well as panel of B cell tumors, were tested. The results demonstrate that the Fc gamma RII is expressed on all pre-B cells and immature B cells in the neonatal spleen and adult bone marrow, on all mature B cells in peripheral lymphoid organs, and on switched B cells in Peyer's patches. Furthermore, the Fc gamma RII was found to be present on B cell tumors representative of all stages of B cell maturation and differentiation. Taken together, the results indicate that Fc gamma RII is expressed during the entire lifetime of the B cell. In addition, examination of spleen cells from neonatal mice revealed a large number of pre-B cells, phenotypically defined as B220+, IgM-. These pre-B cells were present at birth, peaked in number between 2 and 3 wk of age, and became a minor population by day 30. Further phenotypic analysis of these cells demonstrated the expression of the BLA-1 and BP-1 Ag, and the lack of T cell and NK cell markers, thus confirming their assignment to the B cell lineage. Finally, the Fc gamma RII present on these pre-B cells was shown to be functional, by virtue of its ability to bind aggregated IgG.     

Biosynthesis and regulation of fructose-1,6-bisphosphatase and phosphofructokinase in Saccharomyces cerevisiae grown in the presence of glucose and gluconeogenic carbon sources.

The mode of synthesis and the regulation of fructose-1,6-bisphosphatase (Fbpase), a gluconeogenic enzyme, and phosphofructokinase (PFK), a glycolytic enzyme, were investigated in Saccharomyces cerevisiae after growth in the presence of different concentrations of glucose or various gluconeogenic carbon sources. The activity of FBPase appeared in the cells after the complete disappearance of glucose from the growth medium with a concomitant increase of the pH and no significant change in the levels of accumulated ethanol. The appearance of FBPase activity following glucose depletion was dependent upon the synthesis of protein. The FBPase PFK were present in glucose-, ethanol-, glycerol-, lactate-, or pyruvate-grown cells; however, the time of appearance and the levels of both these enzymes varied. The FBPase activity was always higher in 1% glucose-grown cells than in cells grown in the presence of gluconeogenic carbon sources. Phosphoglucose isomerase activity did not vary significantly. Addition of glucose to an FBPase and PFK synthesizing culture resulted in a complete loss, followed by a reappearance, of PFK activity. In the presence of cycloheximide the disappearance of glucose and the changes in the levels of FBPase and PFK were decreased significantly. It is concluded that S. cerevisiae exhibits a more efficient synthesis of FBPase after the exhaustion of glucose compared to the activity present in cells grown in the presence of exogenous gluconeogenic carbon sources. Two metabolically antagonistic enzymes, FBPase and PFK, are present during the transition phase, but not during the exponential phase, of growth, and the decay or inactivation of these enzymes in vivo may be dependent upon a glucose-induced protease activity.     

Development of alfalfa strains with differential tolerance to aluminum toxicity

Summary Aluminum toxicity limits root growth in acid subsoils that are difficult to lime. An alternative to subsoil liming is the development of plants having greater tolerance to Al. Alfalfa (Medicago sativa L.) is considered an Al-susceptible species. Preliminary studies indicated that alfalfa cultivars differ in Al tolerance, but the extreme plant-to-plant variation within cultivars prevented the establishment of clearcut cultivar differences.Tolerant and susceptible plants were selected from each of six cultivars (DuPuits, Atlantic, Team, Buffalo, Grimm, and Sirsa 9) grown on an Al-toxic Bladen soil at pH 4.1 to 4.3. The tolerant selections were repotted and interpollinated to form one population of polycross seed. Susceptible selections were treated similarly to form a second population. These two populations, tolerant and susceptible, were subjected to an additional cycle of recurrent phenotypic selection for tolerance and susceptibility, respectively, to Al-toxic Bladen soil at pH 4.6.Plants from the population selected for tolerance to the acid Bladen soil were significantly higher in both root and top vigor on Al-toxic Tatum soil than plants from the population selected for susceptibility. The results indicated that Al tolerance is a heritable trait in these alfalfa populations and that recurrent selection can be used effectively to develop strains having differential tolerance to Al-toxic soils. The observation that only 2% of the plants from the tolerant population were in the most tolerant class suggests a good opportunity for more progress in selecting toward Al tolerance.