Aspects of the distribution of HbS in the United States

Frequencies of HbS obtained by several screening clinics are analyzed for age, sex, and location effects. All seem to be present in some form, though age and sex effects may be conditional on location. An attempt is made to elaborate the common observation of increasing frequency with age. This is shown to be the result of differences in fertility favoring the normal. A simulation which íncludes 25% admixture was done. The results indicate a genetically relevant New World experience for the population to be about 9–12 generations with the heterozygote having fitness of 0.96–0.99.     

Among the Peoples of the Agreste of Pernambuco

Anthropology, despite its historic role in both creating and dismantling the American racial worldview, seems barely visible in contemporary scholarly and public discussions of "race." The authors argue that race should once again be central to anthropological inquiry, that cultural and physical anthropologists must jointly develop and publicly disseminate a unified, uniquely anthropological perspective. They suggest ways to proceed and identify internal barriers that must be overcome before the anthropological voice can be heard.     

日光温室采光面三效率计算模式及其优化选择研究

本文针对日光温室常见的3种采光面（圆弧面、椭圆和抛物面）,给出了各自采光效率、土地使用率和保温效率（简称三效率）的理论计算模式,并通过分析得出,各个高效采光面上的采光效率均随纬度增加而降低,随距冬至的日数而增加,随作物高度而降低,随高跨比增加而增加。在三种采光面中,无论时间、地点、高跨比和种植高度怎样变化,均以圆弧面的采光效率为最高,椭圆面次之,抛物面最低。另一方面,从土地使用效率来看,椭圆面最高,但它的保温效率最低。因此,采光面形状的选择应因使用对象而宜,本文给出了最佳选择建议。     

Inheritance of the black form of the leopardPanthera pardus

The black form of the leopard is shown to be inherited as an autosomal monogenic recessive to the spotted wild type. Pairings of black animals inter se have a significantly smaller litter size than other possible pairings. Two reasons are offered for this: (1) that black animals may be slightly more inbred than the spotted or (2) black animals may be more prone to pre-natal loss than the spotted. The significance of the latter possibility is briefly discussed in relation to the persistence of the spotted/black polymorphism for areas of South-east Asia.     

Angioarchitecture of the pancreas of the cat

Summary By the use of scanningand transmission electron microscopy, the possible sources of errors in interpretation of the microcirculation of the pancreas can be reduced in comparison to the classical India-ink injection method. Sphincter-like structures in the capillary wall of the cat pancreas are established by pericytes. These sphincters encircle the junctional zones between the endocrine and exocrine capillaries. They are assumed to be regulatory structures of blood flow and to regulate indirectly hormone secretion according to demand.This work was financially supported through the kindness of Eli Lilly GmbH, Bad Homburg, Bundesrepublik Deutschland     

A comprehensive model of the crypts of the small intestine of the mouse provides insight into the mechanisms of cell migration and the proliferation hierarchy

A comprehensive model has been formulated for the proliferative behaviour of the crypts of the small intestine based on individual cell to cell relationships rather than on the average effects of all cells. The model accommodates a wide range of cell kinetic data and provides an insight into the mechanisms involved in cell movement within the columnar sheet of cells and into the relationship between the stem cells and their progeny. The model permits the number of stem cells and transit generations to be estimated. The number of stem cells is predicted to be not less than 4 and not more than 16 per crypt with cell cycle times of between 12 and 32 h respectively. Certain conclusions can be drawn concerning the mechanisms involved in the initial cell displacements after cell division. The model also allows an estimation of parameters which cannot be measured directly such as the degree of cell generation disorder and the amount of dispersion of cells within a cell lineage.     

The importance of the prediction model in the validation of alternative tests

An overview is presented of the validation process adopted by the European Centre for the Validation of Alternative Methods, with particular emphasis on the central role of the prediction model (PM). The development of an adequate PM is considered to be just as important as the development of an adequate test system, since the validity of an alternative test can only be established when both components (the test system and the PM) have successfully undergone validation. It is argued, however, that alternative tests and their associated PMs do not necessarily need to undergo validation at the same time, and that retrospective validation may be appropriate when a test system is found to be reliable, but the case for its relevance remains to be demonstrated. For an alternative test to be considered "scientifically valid", it is necessary for three conditions to be fulfilled, referred to here as the criteria for scientific relevance, predictive relevance, and reliability. A minimal set of criteria for the acceptance of any PM is defined, but it should be noted that required levels of predictive ability need to be established on a case-by-case basis, taking into account the inherent variability of the alternative and in vivo test data. Finally, in view of the growing shift in emphasis from the use of stand-alone alternative tests to alternative testing strategies, the importance of making the PM an integral part of the testing strategy is discussed.     

Implementation of the 1990 recommendations of ICRP in the countries of the European community

The International Commission on Radiological Protection (ICRP) has published new Recommendations in ICRP Publication 60. These 1990 Recommendations provide a System of Radiological Protection that takes account of the most recent information on the effects on health of exposure to ionising radiation and trends in the setting of safety standards. Within the European Community the Recommendations fo the ICRP are implemented through a Euratom Directive which is binding on member states, a draft of which has been accepted by the Article 31 Group and must eventually be ratified by the Council of Ministers. It is expected that the new directive will broadly endorse the principles of protection given in the 1990 Recommendations together with the dose limits for both workers and members of the public. There are likely to be some modifications to the 1990 Recommendations that are mainly related to their practical application. As it will be some time before the directive is incorporated into national regulations, a number of member states have taken independent initiatives. The development of dose constraints for occupational, medical and public exposure is being seen by national organisations in many countries as a significant new approach to improving standards of radiation protection.     

Limitations of pH-potentiometric titration for the determination of the degree of deacetylation of chitosan

The degree of deacetylation (DDA) of chitosan determines the biopolymer's physico-chemical properties and technological applications. pH-Potentiometric titration seems to offer a simple and convenient means of determining DDA. However, to obtain accurate pH-potentiometric DDA values, several factors have to be taken into consideration. We found that the moisture content of the air-dry chitosan samples can be as high as 15%, and a reasonable fraction of this humidity cannot be removed by ordinary drying. Corrections have to be made for the ash content, as in some samples it can be as high as 1% by weight. The method of equivalence point determination was also found to cause systematic variations in the results and in some samples extra acid as high as 1 mol% of the free amino content was also identified. To compensate for the latter effect, the second equivalence point of the titration has to be determined separately and the analytical concentration of the acid be corrected for it. All the corrections listed here are necessary to obtain DDA values that are in reasonable agreement with those obtained from (1)H NMR and IR spectroscopic measurements. The need for these corrections severely limits the usefulness of pH-metry for determining accurate DDA values and thus potentiometry is hardly able to compete with other standard spectroscopic procedures, that is, (1)H NMR spectroscopy.     

Changes of the internal organization of the plasma membrane correlated to the regeneration potency of the cell

Internal organization of the plasma-membrane of rat thymocytes and pituitary tumor cells (GH₃) was experimentally altered by low temperature and either changing osmolarity or adding drugs destroying the cytoskeleton. These treatments induce reversible aggregation of intramembrane particles of the plasma membrane. Thin section electron microscopy of the hypotonically shocked cells show all the cell organelles to be extremely swollen and the cytoplasmic space to be rather empty. Returned to physiological conditions, the cells show normal morphological aspects, accompanied by ‘normal’ permeability properties of the plasma membrane; the aggregation of intramembrane particles is reversed. The proliferation behaviour of GH₃-cells is not affected by this treatment. This demonstrates a high regeneration potency of the mammalian cell and leads to the assumption that molecular components which are important for the survival of the cell must be structural (membrane) bound.     

Cytophotometric analysis of the cell population composition of the the preoptic area of the hypothalamus in the common frog

DNA contents in squashed cells of the adult frog hypothalamic preoptic region (HPR) were measured using the Feulgen and UV cytophotometry techniques. The histone-DNA ratio in the cell nucleus was determined by means of a combined Feulgen-heparin-Alcian blue staining procedure. The nuclei of the vast majority of HPR cells have a diploid DNA content. However, in cells of this group the mean values of DNA amount and the distribution range were always higher than those in hepatocytes used as a diploid standard. Such a heterogeneity in DNA content in the diploid part of HPR cell population could apparently suggest some differences in the nuclear chromatin arrangement to be always higher in spring before the frog spawning, and it seems to be characteristic of this type of cells. About 1 per cent of cells with hyperdiploid surplus of DNA (H2c cells) as well as of tetraploid cells (4c and 2c X 2 cells) is found in HPR in frogs sacrificed both in winter and in summer. The quota of these cells has no reference either to the frog's age or to the annual cycle. The fact that the mean DNA values in H2c and 4c cells are much higher than in the standard cannot be explained by the presence of different amounts of nuclear proteins only. It is suggested that at least some part of the highest DNA values may be due to an actual extra DNA synthesis in a small constantly existing pool of HPR cell population.     

On the analysis of competition at the level of the individual plant

Summary The extent to which some measure of local crowding can account for the performance of individual plants is examined with reference to populations of two species of annual plant. Only a relatively small proportion of the variation in individual plant yield could be accounted for by measures of local crowding. These included the number of close neighbours, an estimate of the area available to each plant and competitive pressure. A multiple regression that took account of both emergence time and local crowding increased the proportion of variance that could be accounted for up to 50%. Computer simulations of the growth of indivudual plants in monoculture were then caried out in order to determine whether the unexplained variation resulted from fundamental flaws in the models or from unaccounted for sources of variation in the field. The results from the simulations again indicated that only a relatively low proportion of the variation in individual plant yield could be accounted for by emergence time and local density, even though these were known to be the only variables present. These findings are discussed in relation to the relative importance of one-sided and two-sided competition, and the complex cross-correlations that occur between individuals in plant populations. These two factors will make it very difficult for field workers to determine accurately what factors determine individual plant yield and in particular to predict the effects of local crowding on the performance of individual plants.     

Constraints on dispersal and the evolution of the avifauna of the Northern Hemisphere

One could predict that the capacity for travelling great distances might predispose long-distance migratory birds to be good colonists and to exhibit wider geographic distributions than their non-migratory or short-distance migratory relatives or non-volant mammals. This prediction is not supported by the data on avian biogeography. The distributions of species, genera and families of North American and Eurasian birds and mammals are indeed related to migratory status, but long-distance migratory birds exhibit a great deal of biogeographic regionalism. In particular, at all taxonomic levels their distributions tend to be confined to either the Eastern or Western Hemisphere, suggesting that there has been little successful east–west dispersal between North America and Eurasia. Compared to non-migratory birds, short-distance migratory birds and non-volant mammals, long-distance migrants appear to be subject to severe constraints on their physiology, behaviour and ecology, w hich have prevented colonization of distant regions.     

An hypothesis concerning the role of the Golgi apparatus in the phenomenon of memory

The hypothesis considers the anatomy and physiology of the memory-storing neuron from the viewpoint that an eccentrically placed nucleus with a Golgi Apparatus situated between it and the proximate cell membrane could be the mechanism for the storage and retrieval of experience and thought processes. Metabolites which enter the Golgi Apparatus are filtered and refined before being discharged from the surface which faces the cell membrane. They travel by the shortest route to a special location on the nearest part of the cell membrane. At this "favoured spot" the action potential is reactivated before the metabolites reach other parts of the membrane. Afferent impulses arriving via the synapses at the "favoured spot" and its tributary dendrites have priority controls the specific polarity of the cell, enabling it to record, store and reproduce the memory of its initial stimulus. Reinforcing stimuli cause the eccentric nucleus and Golgi Apparatus to move nearer to the favoured spot. This mechanism could be the basis of memory. The hypothesis may be applied to other observed phenomenon of brain function and might be submitted to experiment confirmation.     

On the possible mechanism of the protective effect of Escherichia.

A model on a HEp-2 cell culture was elaborated, permitting the study of the ability of microbes to be adsorbed an to proliferate on the surface of cells and of the mechanism of their protective effect. The ability of E. coli strains to be adsorbed and to proliferate on the surface of a cell culture was found to differ. It has been demonstrated that the protection of the cell culture from subsequent infection with virulent Shigella can be explained not only by the antagonistic activity of E. coli strains, but also by their ability to be adsorbed and to proliferate on the surface of cells. A similar mechanism of protective effect is supposed in preparations of the Colibacterin type.     

About the presence of interstitial cells of Cajal outside the musculature of the gastrointestinal tract

Santiago Ramon y Cajal observed a special cell type that appeared to function as endstructures of the intrinsic nervous system in several organs. These cells were structurally and functionally further characterized in the gut musculature and named interstitial cells of Cajal (ICC). In recent years, interstitial cells have been identified in the vasculature, urinary tract, glands and other organs. Their morphologies and functions are just beginning to be clarified. It is likely that amongst them, subtypes will be discovered that warrant the classification of interstitial cells of Cajal. This "point of view" continues the discussion on the criteria that should be used to identify ICC outside the musculature of the gut.     

Fluidity of the phospholipid bilayer of the endometrium at the time of implantation of the blastocyst--a spin label study

The endometrial phospholipid bilayer is shown to be in a highly fluid and polar state at the time of implantation in Mus musculus as evidenced from a spin label study using the stearic acid spin label, 5-doxyl stearate. The positive correlation observed between the superoxide anion radical levels and the fluidity and polarity state of the endometrial cells points towards the possibility of the mediation of this condition of unsaturation of fatty acids to be an act of the superoxide anion radical.     

Role of the adaptor protein CIKS in the activation of the IKK complex

Nuclear factor kappaB (NF-kappaB) plays a pivotal role in numerous cellular processes, including stress response, inflammation, and protection from apoptosis. Therefore, the activity of NF-kappaB needs to be tightly regulated. We have previously identified a novel gene, named CIKS (connection to IkappaB-kinase and SAPK), able to bind the regulatory sub-unit NEMO/IKKgamma and to activate NF-kappaB. Here, we demonstrate that CIKS forms homo-oligomers, interacts with NEMO/IKKgamma, and is recruited to the IKK-complex upon cell stimulation. In addition, we identified the regions of CIKS responsible for these functions. We found that the ability of CIKS to oligomerize, and to be recruited to the IKK-complex is not sufficient to activate the NF-kappaB. In fact, a deletion mutant of CIKS able to oligomerize, to interact with NEMO/IKKgamma, and to be recruited to the IKK-complex does not activate NF-kappaB, suggesting that CIKS needs a second level of regulation to efficiently activate NF-kappaB.     

Morphology of severe mycoses. Role of the pathologist in the diagnosis

Mycoses are diseases caused by fungi. To be regarded as pathogenic, a fungus has to be able to complete a number of steps in order to initiate infection. Although culture remains the gold standard to diagnose the causative agent, presumptive identification of these fungi in histologic slides is of great value because invasion is only demonstrated in tissue sections. When culture is not available, histopathologic examination may be the sole source of information about the nature of the infection. To make a diagnosis, the pathologist needs to be familiar with the morphologic appearance of the different types of fungi, and has also to be aware of the limitations in their identification. The purpose of this work is to review the current problems on this subject, specially referring to the most frequent severe mycoses of our environment.     

Mechanism of the reaction catalyzed by the DNA untwisting enzyme: attachment of the enzyme to 3'-terminus of the nicked DNA.

The rat liver DNA untwisting enzyme introduces a transient nick into duplex DNA. The enzyme has been shown to be covalently attached to one of the ends of the broken strand in the nicked intermediate (Champoux, 1977). The broken strand containing bound enzyme is shown to be susceptible to phosphorylation by polynucleotide kinase. Therefore, the DNA untwisting enzyme must be attached to the strand at the 3′-phosphate terminus, and this linkage probably conserves the energy required for resealing the single-strand break.