Location by odour and turn selection as two stages in the spontaneous alternation of rats.

Rats were given two free unrewarded trials per day in different T-mazes, oriented at 90 degrees to each other, and wiped with either Cajuput or Anise, which produced distinctive odours. The rate of spontaneous alternation was 82.8 per cent when the same odour was present on both trials, 62.5 per cent when the odour was changed between trials. This result was taken to support the hypothesis that alternation is a two-stage process, involving location then turn selection, and that odour is one of the stimuli used by the rat in locating itself.     

Effects of monoenergetic X-rays with resonance energy of bromine K-absorption edge on bromouracil-labelled E. coli cells

In order to examine enhanced killing that might be induced by Auger cascades in the incorporated atoms in cells, bromouracil(BrU)-labelled E. coli cells were irradiated with monoenergetic X-rays at 13.49 and 12.40keV, just above and below the K-absorption edge of bromine. In both cases BrU-labelled cells were more sensitive for killing than were normal cells. However, when the degree of BrU-sensitization was compared between the two energies of X-rays, the enhanced killing at 13.49 keV was only small, 2 +/- 8 per cent based on the D0 value in saline. By the addition of DMSO, which is believed to suppress radical-mediated effects, killing of BrU-labelled cells was enhanced at 13.49 keV by 8 +/- 4 per cent as compared with 12.40 keV, based on D0. These results have been examined in terms of absorbed energy in BrU-labelled cells and in terms of the number of induced Auger events.     

Testing of granulocyte function after gravity leukapheresis

In a laboratory model granulocyte concentrates are produced by a procedure of gravitational leukopheresis. Hydroxyaethyl starch (HAS) served as an accelerator of sedimentation. In a parallel test arrangement a preparation of hydroxyaethyl taken from the industrial production of the GDR and a control preparation (Plasmasteril) was used. The regaining rate of this method amounts to about 70 per cent with 98 per cent of living cells in the concentrates. Vitality, performance of phagocytosis and ability of migration will only reduce to a slight degree during the first 4 hours, after that time, however, they will decrease significantly. There are no essential differences between the results of both preparations.     

Needle biopsy in diagnosis of prostatic cancer

Four methods available for the diagnosis of carcinoma of the prostate-digital rectal evaluation, prostatic smear, needle biopsy and open perineal or transurethral biopsy-were studied and correlated.One hundred ten patients with clinical indications of cancer of the prostate were subjected to needle biopsy and open perineal or transurethral biopsy. Seventy of the same patients had prostatic smear examination. Using the open perineal biopsy or the positive transurethral biopsy as the standard, the accuracy of prostatic palpation, prostatic smear and needle biopsy were obtained.A high degree of correlation (74 per cent) was demonstrated between digital rectal evaluation and positive surgical biopsies in both early and late cases. There were 17 false positive clinical diagnoses. The prostatic smear showed an overall correlation of 45 per cent when compared with the results of positive surgical biopsy. The overall accuracy of needle biopsy was 73 per cent. However, in the last 39 cases, including eight in which the carcinomas were of groups A and B (curable), the needle accuracy was 100 per cent. When there is clinical indication of malignant disease of the prostate, needle biopsy of the lesion is warranted and should be done before definitive or palliative treatment is undertaken.     

Application of computer image analysis in endocrine cell quantification

Computer image analysis was applied for quantifying endocrine cells by using an automatic standard sequence analysis operation. Two parameters were used, namely the number of cells per mm3 of epithelial cells and the cell secretory index (the volume of the immunore active secretory granules per cell). The first indicates the variation in the anatomical peptide-producing unit and the second the synthesis and secretion activity of the cell. The endocrine cells chosen in this study were chromogranin-immunoreactive cells and secretin- immunoreactive cells in the human duodenum. The measurements were made by five different investigators with different backgrounds in order to evaluate the effect of the intra- and inter- individual variation. This study showed that the intra- and inter-individual variation had no impact on the results. Comparisons with the classical point-counting method considered to be easy and most efficient in volumetry showed that the present approach is between two and three times faster and less strenuous for the performer. It is concluded that this approach seems to be suitable for adaptation in morphometric studies when information is required about the changes in the number of endocrine cells and about changes in secretory activities. This revised version was published online in November 2006 with corrections to the Cover Date.     

Identification with G and R banding of the position of breakage points induced in human chromosomes by in vitro x-irradiation.

The aberrations seen in chromosomes of human peripheral-blood lymphocytes, X-irradiated in vitro, have been analysed in three types of preparations, treated to give G-banding; R-banding; and G-banding followed by R-banding on the same cells. The data from cells subjected to both banding techniques reveals that 30 per cent of the sites of chromosome breakage are situated at he interfaces between dark- and - light-stained bands. The results of all the analyses show that approximately 30 per cent of all breaks were located in either the telomere (19-5 per cent) or centromere (11-3 per cent) regions. Chromosomes rich in R-band material were not preferentially damaged, but chromosomes 12, 15, and particularly 17, were involved in aberrations more frequently than would be expected on the basis of their length. No breaks were found on the Y chromosome in the 114 male cells analysed, but the X did not appear to be spared from damage either in the male cells analysed, but the X did not appear to be spared from damage either in the male cell or the 136 female cells analysed. G and/or R-banding enables a much more accurate analysis of aberrations than can be obtained from the use of conventional staining techniques, and with these methods, it is shown that the numbers of induced asymmetrical and symmetrical exchanges are similar.     

The Categorisation of Non-Categorical Colours: A Novel Paradigm in Colour Perception

In this paper, we investigate a new paradigm for studying the development of the colour ‘signal’ by having observers discriminate and categorize the same set of controlled and calibrated cardinal coloured stimuli. Notably, in both tasks, each observer was free to decide whether two pairs of colors were the same or belonged to the same category. The use of the same stimulus set for both tasks provides, we argue, an incremental behavioural measure of colour processing from detection through discrimination to categorisation. The measured data spaces are different for the two tasks, and furthermore the categorisation data is unique to each observer. In addition, we develop a model which assumes that the principal difference between the tasks is the degree of similarity between the stimuli which has different constraints for the categorisation task compared to the discrimination task. This approach not only makes sense of the current (and associated) data but links the processes of discrimination and categorisation in a novel way and, by implication, expands upon the previous research linking categorisation to other tasks not limited to colour perception.     

Bronchial brushing during fiberoptic bronchoscopy for the cytodiagnosis of lung cancer: comparison with sputum and bronchial washings.

In a study of 50 cases of bronchogenic carcinoma in which brushings and washings during fiberoptic bronchoscopy, as well as sputum cytopathologic examinations were performed in the same patients, accuracy rates were respectively: 76 per cent, 76 per cent and 56 per cent. The main cytologic differences setting brush apart from wash and sputum specimens referred to the arrangement of tumor cells as well as the distribution of chromatin within their nuclei. These differences appeared related to cell degeneration which was minimal in brush materials and maximum in sputum specimens. Only six cases were assigned a different cell type of bronchogenic carcinoma when brush cytopathologic diagnoses were compared with results obtained by biopsy or lobectomy specimens. Our findings are consistent with the view that the brush technique is very accurate for the cytodiagnosis of lung cancer and becomes also rather specific once cytologic characteristics of the fresher samples obtained become familiar to the cytopathologist. Non-observance of the special characteristics of these better preserved cellular samples is the major pitfall as to diagnosing, cell typing and judging degree of differentiation of bronchogenic carcinoma in brush cytology specimens.     

RADIATION EFFECTS ON THE GROWTH RATE AND CELL POPULATION KINETICS OF ACTIVELY GROWING AND DORMANT ROOTS OF TRADESCANTIA PALUDOSA

Actively growing and dormant roots of Tradescantia paludosa were exposed to x-rays to compare the radiosensitivity of an actively proliferating tissue with that of one which is not active but is potentially proliferative. The level of effect was ascertained by the degree of change in the rate of root growth 4 days after exposure. Cell population kinetics were measured in control and in irradiated roots to determine whether or not a change was produced either in the number of proliferating cells or in the mitotic cycle duration which was sufficient to explain the altered rate of root growth. Nuclear volumes were also measured to provide an estimate of the relative total target size in actively growing vs. dormant roots. Tritiated thymidine was used to measure the cycle duration and the proportion of cells synthesizing DNA. The results showed that 184 and 305 r respectively were required to reduce the linear root growth rate to 37 per cent of that of the control for actively growing and dormant roots. Mitotic cycle duration, measured 4 days after x-ray exposure, was the same as in the control. The number of proliferating cells, however, was reduced. The rate of cell production in the irradiated roots was reduced to approximately one-half that of the controls. The average nuclear volumes of active and dormant roots were 733 and 491 µ³ respectively; thus the difference in the number of roentgens required to reduce growth to 37 per cent of that of the control can be attributed to the different average nuclear volumes. Therefore, the experiments suggest that part if not most of the differences in sensitivity between an actively dividing and an essentially non-dividing meristematic cell population resides in their different average nuclear volumes. Thus the law of Bergonie and Tribondeau needs to be reinterpreted, since the basic reason for the differences is secondary to whether or not the meristematic cells are proliferating.     

Total sialic acid content of glycophorins during senescence of human red blood cells.

Glycophorins extracted from membranes of young and old human red blood cells have within an error of +/- 1.5% the same sialic acid content when referred to a relative measure of the number of glycophorins. The degree of surface iodination in glycophorins, which was shown to be the same in young and old cells, served as this relative measure. This finding implies that senescent human red blood cells hardly reveal desialylated surface proteins (less than or equal to 3%). However, the sialic acid content per cell was repeatedly reported to be 10 to 15% lower in old than in young cells. Therefore, we conclude 1) that human red blood cells lose intact glycophorin together with membrane during red blood cell senescence, and 2) that removal of desialylated and senescent red blood cells from the circulation proceeds by different routes.     

Relationships between growth and foliar nutrient concentrations in Eucalyptus deglupta

Summary Relationships beween nutrient concentrations and the growth of the fast growing tropical eucalypt E. deglupta were examined at two sites in Papua New Guinea. At the Gogol Valley site a predominantly linear relationship was found between growth and foliar N over the range 0.68–2.04 per cent N. At the Kerevat site the relationship between growth and foliar nutrients was less strongly developed (foliar N varied from 1.77 to 3.36 per cent). The combined data could be described by a second degree polynomial. Height=11.05N – 2.03N² – 3.52P – 4.46.This accounted for 72 per cent of the variation in height. Based on this relationship a tentative critical foliar N concentration (corresponding with 90 per cent of maximum height) of 2.1 per cent is proposed. re]19760128     

Use of partially acidulated rock phosphate as a possible means of minimising phosphate fixation in acid soils

Summary To examine the possibility of minimising phosphate fixation the lateritic soil at various levels of liming was incubated with phosphate rock from U.A.R. acidulated to different degree viz. 0, 10, 20, 50, and 100 per cent both with phosphoric and nitric acid. The soil was incubated for 90 days on addition of different phosphate carriers at the rate of 100 ppm total P₂O₅ containing different proportion of water-soluble, citrate-soluble and insoluble phosphorus. Samples were drawn at an interval of 30 days. Bray's p₁ and pH of the soil samples were measured. The dry-matter yield and uptake of phosphorus by two successive crops of maize grown in pots, the treatments being same as in incubation study, were well correlated with the Bray's p₁. Ground rock phosphate and 10 per cent acidulated material were effective in minimising the fixation in soil of pH 4.0 whereas 50 per cent acidulation was suitable for soils of higher pHi.e. 5.6 and 6.5. H₃PO₄ acidulated material was proved superior to HNO₃ acidulated product. The use of partially acidulated rock phosphate for acid soils may be recommended to receive economic return. Associate Professor Senior Research Assistant.     

Long term retention of 237Np in rats

This interim report summarizes the results of observations during the first year after a single injection of 237Np nitrate (0.2 or 1.0 mg/kg body weight) into adult female rats and further preliminary data obtained with young animals. The retention of 237Np was followed by whole body counting and serial sacrifice of groups of animals. The retention data could be fitted to three-component exponential equations which show no major differences between the two 237Np dose levels. The half-times and extrapolated initial fractions calculated from the first two exponential terms indicate that one fraction, representing about 40 per cent of the injected 237Np was excreted within the first 5 days and an additional 15 per cent within the first 5 months, while the rest was excreted with a half-time of about 3.5 years. This final long term component is assumed to indicate the rate of loss of 237Np from the skeletal compartment. In young animals both whole-body and skeletal retention of 237Np during the first 5 months of observation was about 50 per cent higher than in the adults. Several soft tissue tumours, mostly mammary tumours, have appeared to approximately the same extent in both control and 237Np treated adult rats but no osteosarcomas were detected up to 15 months after injection of 237Np.     

Patterns of intermediate host use and levels of association between two conflicting manipulative parasites.

For many parasites with complex life cycles, manipulation of intermediate host phenotypes is often regarded as an adaptation to increase the probability of successful transmission. This phenomenon creates opportunities for either synergistic or conflicting interests between different parasite species sharing the same intermediate host. When more than one manipulative parasite infect the same intermediate host, but differ in their definitive host, selection should favour the establishment of a negative association between these manipulators. Both Polymorphus minutus and Pomphorhynchus laevis exploit the amphipod Gammarus pulex as intermediate host but differ markedly in their final host, a fish for P. laevis and a bird for P. minutus. The pattern of host use by these two conflicting manipulative parasites was studied. Their incidence and intensity of infection and their distribution among G. pulex were first examined by analysing three large samples of gammarids collected from the river Tille, Eastern France. Both parasites had low prevalence in the host population. However, temporal fluctuation in the level of parasitic infection was observed. Overall, prevalence of both parasite species was higher in male than in female G. pulex. We then assessed the degree of association between the two parasites among their intermediate hosts, using two different methods: a host-centred measure and a parasite-centred measure. Both measures gave similar results; showing random association between the two acanthocephalan species in their intermediate hosts. We discuss our results in relation to the selective forces and ecological constraints that may determine the pattern of association between conflicting manipulative parasites.     

ULTRASTRUCTURE OF THE RESTING AND CONTRACTED STRIATED MUSCLE FIBER AT DIFFERENT DEGREES OF STRETCH

Passive stretch, isometric contraction, and shortening were studied in electron micrographs of striated, non-glycerinated frog muscle fibers. The artifacts due to the different steps of preparation were evaluated by comparing sarcomere length and fiber diameter before, during, and after fixation and after sectioning. Tension and length were recorded in the resting and contracted fiber before and during fixation. The I filaments could be traced to enter the A band between the A filaments on both sides of the I band, creating a zone of overlap which decreased linearly with stretch and increased with shortening. This is consistent with a sliding filament model. The decrease in the length of the A and I filaments during isometric contraction and the finding that fibers stretched to a sarcomere length of 3.7 µ still developed 30 per cent of the maximum tetanic tension could not be explained in terms of the sliding filament model. Shortening of the sarcomeres near the myotendinous junctions which still have overlap could account for only one-sixth of this tension, indicating that even those sarcomeres stretched to such a degree that there is a gap between A and I filaments are activated during isometric contraction (increase in stiffness). Shortening, too, was associated with changes in filament length. The diameter of A filaments remained unaltered with stretch and with isometric contraction. Shortening of 50 per cent was associated with a 13 per cent increase in A filament diameter. The area occupied by the fibrils and by the interfibrillar space increased with shortening, indicating a 20 per cent reduction in the volume of the fibrils when shortening amounted to 40 per cent.     

Survival of V79 cells following simultaneous irradiation with X-rays and neutrons in air or hypoxia

V79 Chinese hamster cells have been irradiated with X-rays and neutrons given simultaneously. The oxygen enhancement ratio and r.b.e. were measured as a function of the proportion of the dose due to the neutrons, which varied from 0 to 100 per cent. These were compared with the values calculated assuming the two types of radiation act independently, following an approach suggested by Curtis. The o.e.r. was less than the predicted value when the neutrons contributed less than about 40 per cent of the total dose. The r.b.e. also did not vary as predicted on the basis of independent action. The 'oxygen gain factor' reached half its maximum value when the proportion of the dose due to neutrons was only about 27 per cent. The results imply that there may be interaction between the damage caused by X-rays and neutrons and that beams having only 20 to 30 per cent of their dose due to high l.e.t. radiation, could be of therapeutic benefit.     

A STATISTICAL ANALYSIS OF DIFFERENCE TESTS WITH REPLICATIONS

This paper proposes a statistical method for difference tests with repetitions. Classical methods for difference tests are based upon the binomial distribution, and are not concerned with the number of repetitions per judge. But when more than one replication of a difference test is required, judgements from different judges are more independent than replicates from the same judge; these two cannot be combined in the classical methods. In this paper, we propose another approach that takes into account two points: the number of repetitions per judge, and the differences within subjects. Two examples are presented to illustrate this approach.     

Organelle association visualized by three-dimensional ultrastructural imaging of the yeast cell

This study was aimed at a better understanding of organelle organization in the yeast Saccharomyces cerevisiae with special emphasis on the interaction and physical association of organelles. For this purpose, a computer aided method was employed to generate three-dimensional ultrastructural reconstructions of chemically and cryofixed yeast cells. This approach showed at a high level of resolution that yeast cells were densely packed with organelles that had a strong tendency to associate at a distance of <30 nm. The methods employed here also allowed us to measure the total surface area and volume of organelles, the number of associations between organelles, and the ratio of associations between organelles per surface area. In general, the degree of organelle associations was found to be much higher in chemically fixed cells than in cryofixed cells, with endoplasmic reticulum/plasma membrane, endoplasmic reticulum/mitochondria and lipid particles/nuclei being the most prominent pairs of associated fractions. In cryofixed cells, similar preferences for organelle association were seen, although at lower frequency. The occurrence of specific organelle associations is believed to be important for intracellular translocation and communication. Membrane contact as a possible means of interorganelle transport of cellular components, especially of lipids, is discussed.     

The distribution of plutonium-214 in rodents.

Plutonium-214 citrate solution at pH 6-5 was injected intravenously or intra-peritoneally into hamsters and rats at a dose of 50 MBq kg-1 (1-35 mCi kg-1). The animals were killed 1 day or 1 week later, and tissues were removed for autoradiography and radiochemical analysis. Plutonium-241 was distributed in rats in the same way as plutonium-239, and is a suitable isotope for high-resolution tissue-section autoradiography. Plutonium deposits in cells consisted of a nuclear and a cytoplasmic component. In the hamster kidney cells, the amount associated with the nucleus was about 55 per cent of the total cellular plutonium at 24 hours after injection. Six days later, it was only about 30 per cent. Plutonium deposits were also characterized in hepatocytes, in the interstitial cells of the testes, in the cells of ovarian follicles, in chondrocytes and in bone cells, including osteoblasts and osteocytes. In bone there appeared to be both an extracellular and intracellular deposit. No evidence was found of substantial incorporation of plutonium into the mineral phase of bone.     

Fluorescence-based analysis of the intracytoplasmic membranes of type I methanotrophs

Most methanotrophic bacteria maintain intracytoplasmic membranes which house the methane-oxidizing enzyme, particulate methane monooxygenase. Previous studies have primarily used transmission electron microscopy or cryo-electron microscopy to look at the structure of these membranes or lipid extraction methods to determine the per cent of cell dry weight composed of lipids. We show an alternative approach using lipophilic membrane probes and other fluorescent dyes to assess the extent of intracytoplasmic membrane formation in living cells. This fluorescence method is sensitive enough to show not only the characteristic shift in intracytoplasmic membrane formation that is present when methanotrophs are grown with or without copper, but also differences in intracytoplasmic membrane levels at intermediate copper concentrations. This technique can also be employed to monitor dynamic intracytoplasmic membrane changes in the same cell in real time under changing growth conditions. We anticipate that this approach will be of use to researchers wishing to visualize intracytoplasmic membranes who may not have access to electron microscopes. It will also have the capability to relate membrane changes in individual living cells to other measurements by fluorescence labelling or other single-cell analysis methods.