The endogenous lectins of the chick blastoderm are present in association with an apolipoprotein in distinct organelles and in the extracellular matrix

Summary Affinity purified preparations of the galactose-binding lectin from gastrulating chick blastoderms consist of three main polypeptides. Two of these have been identified as the 14 kD and 16 kD galactose-binding lectins. A third one migrates in SDS-PAGE gels with a relative molecular weight of 6,500±500 and has been identified as an apolipoprotein (Apo) of plasma very low density lipoproteins, Apo-VLDL-II. We have studied the localization of these polypeptides using immunofluorescence and ultrastructural immunocytochemistry with peroxidase and protein-A gold. The 14 kD lectin occurs in the intracellular yolk where it is mainly present within the electron lucent component. The 16 kD is also present in the intracellular yolk platelets, but tends to predominate in the electron-dense component. In addition, the 16 kD lectin is also present in pleiomorphic yolk-associated organelles and in the extracellular matrix. Apo-VLDL-II is also localized in the electron-lucent component of the yolk platelet and in the extracellular matrix. Our results suggest that the lectin(s) are associated with Apo-VLDL-II in the yolk platelet, and may subsequently become externalized.     

Identification of some lactic acid bacteria from two Zimbabwean fermented milk products

Ten predominant lactic acid bacterial isolates from traditionally fermented milk and four isolates from an industrially fermented milk, Lacto, together with 14 reference strains ofLactobacillus and three ofLactococcus were examined for 32 characteristics. Data were analysed using the simple matching coefficient and clustering was by unweighted pair group average linkage. All the isolated from traditionally fermented milk belonged to the genusLactobacillus. Seven isolates could be identified as belonging toL. helveticus, L. plantarum, L. delbrueckii subsp.lactis, L. casei subsp.casei andL. casel subsp.pseudoplantarum. Three of the isolates could only be identified as either betabacteria or streptobacteria. The four isolates from Lacto were identified asLactococcus lactis. However, they could not be identified to subspecies level.

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Résumé On a examiné 32 caractéristiques de 10 souches de bactéries lactiques isolées de fait fermenté de manière traditionnelle, et de 4 souches isolées d'un lait fermenté industriel, le Lacto, ainsi que 14 souches de référence deLactobacillus et trols deLactococcus. Les données ont été analysées en utilisant le coefficient d'apparienient simple et le groupement par lien moyen de groupe pair non balancé. Toutes les souches isolées du lait fermenté de manfère traditionnelle appartiennent au genteLactobacillus. Sept souches ont pu étre identifiées comme appartenant àL. helveticus, L. plantarum, L. delbruckii subsp.lactis, L. casei subsp.casei etL. casei subsp.pseudoplantarum. Trois de ces souches n'ont pu être identifiées soit comme bétabactéries soit comme streptobactéries. Les quatres souches isolées de Lacto ont été identifiées commeLactococcus lactis. Celles-ci n'ont toutefois pas pu être identifiées jusqu'au stade de sous-espèce.

     

Health checks in general practice: another example of inverse care?

OBJECTIVE--To assess attendance at and the characteristics of patients attending health checks for cardiovascular disease offered in a general practice over a period of five years (1984-9). DESIGN--Medical record audit and postal questionnaire survey. SETTING--One general practice in Oxfordshire with a socially diverse population. PARTICIPANTS--1101 Men and 1110 women aged 35-64 registered with the practice. MAIN OUTCOME MEASURES--Age, sex, marital state, social class, smoking habits, alcohol consumption, and diet. RESULTS--Of the 2211 men and women in the target age group (35-64) in 1989, 1458 (65.9%) had been offered screening and 963 (43.6%) had attended for a health check. Attenders were more likely to be women, aged greater than or equal to 45, married, non-smokers, and of higher social class than patients who did not respond to the invitation. The relative likelihood of non-attendance was 1.24 for smokers, 1.20 for the overweight, 1.16 for heavy drinkers, and 1.28 for those with a less healthy diet, even after adjustment for age, sex, marital state, and social class. CONCLUSIONS--After five years of offering health checks, opportunistically (to men) and in the context of cervical smear tests (to women), less than half of the eligible patients had attended. The likelihood of acceptance of an invitation to attend was inversely related to the patient''s cardiovascular risk for all factors measured except age. A coherent strategy to reduce cardiovascular disease depends on more careful targeting of scarce health service resources and more emphasis on public health measures (such as dietary regulation and tobacco taxation). Doctors should be careful not to absolve the government of its public health obligations by substituting unproved preventive interventions aimed at the individual patient.     

What is Unique About Superoxide Toxicity as Compared to Other Biological Reductants? — A Hypothesis

Usually the toxicity of superoxide is attributed lo its ability to reduce metal ions and subsequently reoxidation of the metal by hydrogen peroxide yields deleterious oxidizing species. As many other nontoxic biological reductants reduce metal compounds, we suggest that part of the mechanism of superoxide toxicity results from its ability to oxidize metal ions bound to biological targets, which subsequently degrade the target via an intramolecular electron Transfer reaction.     

Local production of fibronectin by ectopic human retinal cells

Summary The distribution of fibronectin mRNA and fibronectin in adult human retina and epiretinal membranes was investigated by in situ hybridisation and immunohistochemical techniques. The cells in normal adult retina contained little or no fibronectin mRNA and the retina only showed fibronectin immunoreactivity in retinal vessels. The cells in detached neuroretina did not contain fibronectin message but the vitreoretinal interface of the detached retina exhibited variable fibronectin immunoreactivity. Retinal glia, retinal pigment epithelium and fibroblast-like cells in membranes at the vitreoretinal juncture (epiretinal membranes) showed variable labelling with the fibronectin mRNA probe and all the membranes immunostained for fibronectin. No difference could be detected between membrane cell types in the intensity of labelling with the mRNA probe or for fibronectin immunoreactivity. The results indicate that cells in situ in attached and detached adult human retina do not produce fibronectin. Although fibronectin at the vitreoretinal juncture in retinal detachment is probably partly derived from plasma fibronectin resulting from breakdown of the blood-retinal barrier, ectopic retinal cells produce fibronectin and contribute to the glycoprotein in epiretinal membranes.     

Coevolution of self-fertilization and inbreeding depression. III. Homozygous lethal mutations at multiple loci.

We study the evolution of the rate of self-fertilization in response to deleterious mutations at multiple loci. Although partial selfing induces associations among loci even in the absence of linkage, associations among mutations at different loci are of a smaller order of magnitude than the mutation rate. Genotypes that carry homozygous lethal mutations in heterozygous form at i loci occur in frequencies of the order (Ti) mu i, in which T denotes the number of viability loci and mu the mutation rate. While associations between mutations at different loci remain small even under inbreeding, each viability locus develops an association with the modifier of the rate of self-fertilization that substantially affects the evolution of the breeding system. Positive associations between enhancers of selfing and haplotypes carrying multiple wild-type alleles and positive associations in heterozygosity between the modifier locus and the viability loci promote evolutionary increases in the rate of self-fertilization.     

Fruiting at High Temperature and Its Genetic Control in the Basidiomycete Flammulina velutipes

Of 10 geographic strains of Flammulina velutipes, 4 were found capable of fruiting at 22°C (Fr_H) rather than at the typical 15°C (Fr_L). Crosses made between Fr_H and Fr_L monokaryons were never observed to fruit at 22°C. However, some hybrids did fruit at the intermediate temperature of 18°C when grown on appropriate substrates, indicating incomplete dominance of the low-temperature requirement. Analysis of progeny of five Fr_H × Fr_L crosses indicated that a minimum of two genes appears to control the requirement for fruiting at ≤15°C. The genes are not closely linked to either incompatibility locus.     

Enigmatic Cyst-Forming Sporozoon in the Spinal Cord of a Dog

A female racing greyhound dog was presented to the clinic at the age of 3 months with a 2 months’ history of irregular hindleg movements and thin hindleg muscles. On examination 1 month later, a squatting standing posture, a week proprio-ceptive positioning reaction, and severe atrophy and pain of the lumbar and thigh muscles, were evident. The dog was sacrificed and necropsied. The adrenals, hindleg muscles, kidneys, myo-cardium, peripheral nerves, spinal cord, thyroid, and tonsils were fixed in 10 % neutral buffered formalin and processed for histo-pathology.     

Therapy for acute myeloid leukemia in 119 adults: a comparison of two treatment protocols

Of 119 patients with acute myeloid leukemia, 69 were treated with Adriamycin, Vincristine and Cytosine Arabinoside (Therapy 1) and 50 with Daunorubicin, Cytosine Arabinoside and 6-Thioguanine (Therapy 2) as well as a consolidation therapy. The maintenance therapy with Cytosine Arabinoside and 6-Thioguanine was the same for both groups. The complete remission rate was 44% for Therapy 1 and 68% for Therapy 2 (p less than 0.05). - The median values for remission duration were 7 and 13 months respectively (p = 0.10); for survival time the median values were 18 and 19 months. These figures show in retrospect that high remission rates can be attained through intensive induction therapy and that longer remission duration is correlated with more aggressive induction therapy. A mild form of maintenance therapy seems to have little effect on the duration of complete remission.     

Selection studies on anthelmintic resistant and susceptible populations of Trichostrongylus colubriformis of sheep

Waller P. J., Dobson R. J., Donald A. D., Griffiths D. A. and Smith E.F. 1985. Selection studies on anthelmintic resistant and susceptible populations of Trichostrongylus colubriformis of sheep. International Journal for Parasitology15: 669–676. A T. colubriformis population (BCK), formerly resistant to benzimidazole anthelmintics, but now highly resistant to levamisole after 6 years exposure to this drug alone in the field, was passed through 12 generations in the laboratory in three separate lines exposed either to selection with thiabendazole or levamisole, or to no selection. Another population (McM) not previously exposed to these anthelmintics was treated similarly in two lines, selected with thiabendazole or not selected.Selection with thiabendazole resulted in a return of benzimidazole resistance in the BCK line which occurred faster than in the McM line, but a similar level of resistance was reached in each by the twelfth generation. Resistance ratios in both selected lines compared with the unselected McM line were less than 20: 1, and only 1.5 times the recommended dose rate of thiabendazole was required to remove more than half of the resistant population. This suggests that a polygenic vigour tolerance rather than a specific resistance had been selected.In the case of levamisole resistance, the BCK population was found to contain two distinct subpopulations, one susceptible and the other highly resistant. Resistance ratios for the highly resistant subpopulation were greater than 4000: 1, implying a specific resistance controlled by a major gene. During the 12 generations of levamisole selection, the proportion of resistant phenotypes fluctuated about an average level of 70%, suggesting that susceptibility alleles were being maintained in the population through superior heterozygote fitness. This conclusion is supported by a significant decline in levamisole resistance in the absence of levamisole selection. Moreover, thiabendazole selection hastened the reversion to levamisole suceptibility.The results provide support for the reintroduction of a benzimidazole anthelmintic to control this helminth population, and for a slow rotation in the use of drugs with different modes of action.