longitudinal diffusion along the nephron during stop flow

A mathematical analysis is presented which shows that during stop flow experiments longitudinal diffusion of solute along the nephron is of too small a magnitude to interfere with the interpretation of data. This work was supported in part by contract NONR 595(17) with the Office of Naval Research, U.S. Navy.     

Identifiability of DNA distribution from flow cytometric data with cell debris

In flow cytometric measurement of cell DNA distribution one of the major problems is accounting for the effect of fragmentation in the staining process. This work considers a recent probabilistic model that has been proposed for the fragmentation process and species under which conditions it is possible to uniquely identify the DNA distributions of the original population using flow cytometric data. Attention is given both to the normal and to the polyploid case. This work was partially supported by a grant of the Italian National Research Council, Special Project “Oncology”, contract number 84.00632.44.     

Formation of amino acids by cobalt-60 irradiation of hydrogen cyanide solutions

Aqueous solutions of hydrogen cyanide (0.004–0.1M) were exposed to cobalt-60 gamma rays. Among the products formed on hydrolysis of the irradiated solution; glycine, alanine, valine, serine, threonine, aspartic acid, and glutamic acid have been identified.Portions of this work were performed at the NASA-Ames Research Center, Moffett Field, California, 94035.     

A Schedule Including Cold Treatment to Facilitate Somatic Chromosome Counts in Certain Forage Grasses

Pretreatment at low temperature of root tips of grass grown from tillers in small beakers was found to contract somatic chromosomes and thus facilitate determination of chromosome number. A modification of Randolph's infiltration and card technics has been adapted to working with root tips from large numbers of plants.     

Man/machine interaction in adaptively controlled experimental conditions

Systems in which a human subject interacts with an adaptive control mechanism through display and response facilities are examined. A cybernetic model is discussed, together with supporting experimental data. The research reported in this paper has been supported by the Air Force Office of Scientific Research, under Contract AF. 61.052.640. (for Cybernetic models for learning) and by the Aerospace Medical Research Laboratories A.F.C.S., under contract AF. 61.052.402. (for adaptive teaching systems), through the European Office for Aerospace Research.     

Relationship of trace metals to the alcohol-effect in citric acid synthesis by Aspergillus fonsecaeus

Summary Synthesis of citric acid by Aspergillus fonsecaeus in a basal medium supplemented with trace metals (iron, zinc, copper, and manganese) and methanol has been investigated. Methanol was found to be stimulatory to acid synthesis when manganese or manganese and iron were present. No other mineral tested could be substituted for manganese in the presence of the alcohol. However, comparable yields of citric acid could be obtained if methanol were deleted, the concentration of iron increased and zinc substituted for manganese.This investigation was conducted under a contract with the United States Department of Agriculture, authorized by the Research and Marketing Act, and administered through the Northern Regional Research Laboratory.     

Somatic cell genetics resource for research in aging. The National Institutes of Health plan for an expanded program in cellular aging.

A mutant cell bank in support of research in aging has been established at the Institute for Medical Research, Camden, N.J. The bank is under contract support of the Adult Development and Aging Program of the National Institute of child Health and Human Development. We anticipate that the bank, with associated services such as an annual workshop, will facilitate the growth of the NIH grant-supported cellular aging research program and thus contribute to the elucidation of mechanisms in human aging at the cellular and molecular level.     

Cellulase Facilitated Squash Preparations of Vicia Faba Chromosomes for Quinacrine Fluorescent Staining

This paper is partially based on work performed under contract with the U. S. Atomic Energy Commission at The University of Rochester Atomic Energy Project and has bcen assigned Report No. UR-3490-238, and has also been partially supported by Grant USPHS GM0933.     

Milk composition varies in relation to the presence and abundance of Balantidium coli in the mother in captive rhesus macaques (Macaca mulatta)

Primate infants require extensive maternal investment, and lactation is the most expensive aspect of this investment. However, the relationship between maternal condition and milk composition has been largely uninvestigated in primates. To better understand this relationship, I collected mid-lactation milk samples from 46 captive multiparous rhesus macaques (Macaca mulatta) at the Caribbean Primate Research Center, Sabana Seca Field Station, Puerto Rico. The maternal variables assessed were age, weight, weight for crown-rump length (CRL), and presence of parasites. Additionally the analysis included infant age, weight, and sex. Protein concentration in milk showed little interindividual variation, whereas fat had a high variance. Mothers without the lower intestinal parasite Balantidium coli had a significantly higher fat concentration in milk than mothers with B. coli, but other parasite species (Trichuris trichiura and Strongyloides fulleborni) were not associated with milk fat concentration. Females with younger infants had a higher fat concentration in their milk than mothers with older infants; however, the association between B. coli and milk fat remained significant after controlling for infant age. These results, obtained from a well fed captive population, indicate that even small differences among mothers are associated with milk composition.     

Biochemical genetics of Chinese hamster cell mutants with deviant purine metabolism. VI. Enzymatic studies of two mutants unable to convert inosinic acid to adenylic acid

Ade^–H and ade^–I are two auxotrophic mutants of Chinese hamster ovary (CHO-K1) cells which specifically require adenine as the purine source to grow. The enzymatic defects of these mutants were examined in cell-free extracts. It was found that ade^–H did not have any detectable adenylosuccinate synthetase activity and ade^–I was defective in the adenylosuccinate lyase enzyme. The relevance of adenine-requiring mutants to the study of the regulation of purine metabolism in mammalian cells is discussed.This work was supported by research grants from the National Institute of Aging (AG00029) and the National Foundation, March of Dimes (1-423), and by a contract from the Center for Toxicological Research, Food and Drug Administration (72-213). David Patterson is a recipient of a Research Career Development Award from the National Institute of Arthritis, Metabolic and Digestive Diseases (AM00044).Contribution (No. 218) from the Eleanor Roosevelt Institute for Cancer Research.     

Study of age dependent half-life of iodine in man: A reinforcement-depletion urn model

An urn contains balls ofs different colors. The problem of the reinforcement of a specified color and random depletion of balls has been considered by Shenton (1981, 1983). In this paper, the theory is applied to the biological age dependent half-life of radioactive iodine in man; the data of Cook and Snyder (1965) is used. The intake of radioactive iodine and its retention subsequently is studied. Research sponsored by the Office of Health and Environmental Research, Office of Energy Research, U.S. Department of Energy under contract DE-AC05-840R21400 with the Martin Merietta Energy Systems. Inc.     

Theory of the mitotic index and its application to tissue growth measurement

Analysis is made to show that the mitotic index is simply proportional to the ratio of the duration of mitosis (T) to the intermitotic time only under special conditions. In the case of exponential growth of cell population the simple proportionality hold if the product ofT and the growth constant is small. For power law (t ⁿ ) growth of cell population the simple proportionality holds only when a steady state of growth has existed for at least ten intermitotic periods. The simple proportionality does not apply in conditions of transient growth. This document is based on work performed at Los Alamos Scientific Laboratory of the University of California under government contract W-7405-eng-36 and the information contained therein will appear in Division V of the National Nuclear Energy Series (Manhattan Project Technical Section) as part of the contributions of the Los Alamos Laboratory.     

Exploring Ethograms in the Schoolyard: A Lesson on Animal Behavior

This article highlights a core lesson that has been used in a number of Lincoln Park Zoo educational programs. The lesson teaches students to conduct an ethological, or animal behavior, study on a bird. This study can be implemented in a variety of outdoor settings, including a park, schoolyard, or zoo. Using an ethogram, students will practice inquiry skills such as making observations, collecting and analyzing data, and sharing results. This type of inquiry-based research is commonly conducted at Lincoln Park Zoo and allows students to make a connection between their work and that of our practicing researchers. Furthermore, this lesson supports the recommendations of the National Research Council by providing students with an opportunity to engage in scientific inquiry and to utilize research skills in an outdoor setting.     

An investigation of the cochlear microphonic response of two species of echolocating bats:Rousettus aegyptiacus (geoffroy) andPipistrellus pipistrellus (Schreber)

Summary The cochlear microphonic (CM) responses of two species of echolocating bats:Rousettus aegyptiacus andPipistrellus pipistrellus have been investigated (Figs. 1 and 3) and the responses have been shown to have a single major peak corresponding with the lower range of frequencies produced in echolocation.My thanks are due to Professor Don R. Arthur for providing laboratory facilities for this work and Dr. J. D. Pye for advice during this study and for much valuable unpublished information on calls produced by the bats in this study, and also to Dr. P. Racey for the pipistrelles. This research was made possible by a Science Research Council grant and was sponsored in part by the Air Force Office of Scientific Research under contract number AF61(052)-876 to Dr. Pye. The author was a Harold Row student of King's College.     

Information and effective number of meioses in linkage analysis

In this paper we introduce two information criteria in linkage analysis. The setup is a sample of families with unusually high occurrence of a certain inheritable disease. Given phenotypes from all families, the two criteria measure the amount of information inherent in the sample for 1) testing existence of a disease locus harbouring a disease gene somewhere along a chromosome or 2) estimating the position of the disease locus.Both criteria have natural interpretations in terms of effective number of meioses present in the sample. Thereby they generalize classical performance measures directly counting number of informative meioses.Our approach is conditional on observed phenotypes and we assume perfect marker data. We analyze two extreme cases of complete and weak penetrance models in particular detail. Some consequences of our work for sampling of pedigrees are discussed. For instance, a large sibship family with extreme phenotypes is very informative for linkage for weak penetrance models, more informative than a number of small families of the same total size.Research sponsored by the Swedish Research Council, under contract nr. 626-2002-6286.Acknowledgement The author wishes to thank two referees for helpful comments on an earlier version of the paper.     

Cultivation of the exoerythrocytic stage ofPlasmodium berghei in primary cultures of mouse hepatocytes and continuous mouse cell lines

Summary Plasmodium berghei exoerythrocytic (EE) stages have been cultured in vitro in human continuous cell lines and primary cultures of both human and rat hepatocytes. Although the predominant experimental model of irradiated sporozoite-induced protective immunity is the mouse,P. berghei has not been cultivated in primary mouse hepatocytes or in continuous mouse lines. Because of this, target cells are not available for determining if these immunized mice produce cytotoxic T lymphocytes (CTLs) that recognizeP. berghei antigens expressed on hepatocytes in the context of class I major histocompatability (MHC) antigens. We report the development of methods for cultivating the (EE) stage ofP. berghei in murine hepatocytes and in two cell lines derived from the livers of BALB/c mice; one line produced from a primary hepatocyte culture and the other produced by fusion of mouse hepatocytes with a continuous rat liver line. Mature parasites were detected by microscopy and by DNA probe in both cell lines, each of which supported complete development ofP. berghei liver stages and production of infectious merozoites. Since class I MHC antigens are present on the surface of primary hepatocytes and the mouse X rat hybrid line, these cells can be used to detect cytotoxic T cells against liver stage parasites. This work was supported by the Naval medical Research and Development Command, Bethesda, MD, work unit no. 3M161102B510AK111, ONR contract N00014-83-C-0355, and by contract DPE-0453-C-00-3051-00 of the U.S. Agency for International Development, Washington, D.C. The opinions and assertions herein are not to be construed as official or as reflecting the views of the Navy Department or the naval service at large. The experiments reported herein were conducted according to the principles set forth in the current edition of the “Guide for the Care and Use of Laboratory Animals”, Institute of Laboratory Animal Resources, National Research Council, DHHS, Pub. no. (NIH)85-23     

A cyclic pattern of hydrogen evolution by Anabaena flos-aquae

Summary Photoproduction of H₂ from water by Anabaena flos-aquae in a batch reactor (flowing argon gas phase) followed a reproducible cyclic pattern. Chloramphenicol inhibited events in the cylce, indicating a requirement for protein synthesis.This work was done while the author was employed at the Northern Regional Research Center, U.S.D.A., A.R.S., Peoria, I11Operated by the Union Carbide Corporation under contract W-7405-eng-26 for the U.S. Department of Energy     

Discussion: McCulloch-Pitts and related neural nets from 1943 to 1989

The McCulloch-Pitts paper “A Logical Calculus of the Ideas Immanent in Nervous Activity” was published in theBulletin of Mathematical Biophysics in 1943, a decade before the work of Hodgkin, Huxley, Katz and Eccles. The McCulloch-Pitts neuron is an extremely simplified representation of neural properties, based simply on the existence of a threshold for the activation of an action potential. This work has been supported in part by Grants from the University of Chicago Brain Research Foundation, and the U.S. Department of the Navy, Office of Naval Research (Grant No. N 00014-89J-1099).     

Three hundred years of Taungya: A sustainable system of forestry in south China

Taungya is a system of forest management in which land is cleared and planted initially to food crops. Seedlings of desirable tree species are then planted on the same plot, leading in time to a harvestable stand of timber. Taungya is believed to have been developed by the British in Burma during the nineteenth century. Historical research indicates that successional systems of forest management which follow the pattern of taungya have been used for at least three centuries by ethnic minorities in and by the Han population. The resilience of these systems is associated with economic and social factors which have made the cultivation of trees an adaptive strategy of land use for the inhabitants of the highlands of southern China.Field Research in China for this paper was made possible by a grant from the Conservation and Research Foundation, New London, Connecticut.     

Genetic and population studies of quantitative levels of adenosine triphosphate in human erythrocytes

The mean content of ATP in red cells of American Negroes is significantly less than the mean level in American Caucasians. This is compatible with the hypothesis that the quantitative level of ATP in red cells may be involved in selective processes related to falciparum malaria. There is no evidence of a sex effect on levels of ATP in either population. Family studies conducted in both populations indicate that the quantitative level of red cell ATP is at least partially inherited. Studies of a number of biochemical characteristics of red cells have been conducted in an effort to elucidate the mechanism of genetic and biochemical control of quantitative levels of erythrocytic ATP. These studies have been negative. Although other studies have demonstrated that thalassemia trait influences the level of red cell ATP, the presence of sickle cell trait or G-6-PD deficiency, the other two systems postulated to be involved in malaria protection, did not result in significant differences in mean red cell ATP content.The work reported in this paper was supported in part by the Research and Development Command, Office of the Surgeon General, Department of the Army, under contract DA-49-193-MD-2855 with the Department of Medicine, University of Michigan. With respect to this support, it is contribution number 167 from the Army Research Program on Malaria. The work was also supported in part by USPHS grant AM 09381 and USPHS Career Development Award 1-K3-AM 7959.