Starvation-induced changes in secretin-like immunoreactivity of human plasma

Levels of secretin-like immunoreactivity in the plasma of 50 starved subjects were measured by radioimmunoassay and rose from 18 ± 3 (S.E.) pg/ml after 12 h, to 103 ± 12 pg/ml (P<0.005) after 36 h. The assay antibodies were found to be specific for a region of secretin located towards the C-terminal residue. Lactoperoxidase was used to label the secretin with ¹²⁵I and ion-exchange chromatography on SP-Sephadex C-25 was used to putify the labelled product.The plama immunoreactivity was purified by immunoaffinity chromatograpy on antibody-Sepharose conjugates and characterised by gel-filtration on Sephadex G-50 calibrated with molecular weight markers. After a 12-h fast, 10–20% of the immunoreactivity had a molecular weight of about 12 000, possibly due to precursors of secretin. Most of the remainder was smaller than secretin with molecular weight of less than 3000. This material comprised over 90% of the plasma immunoreactivity after a 36-h fast and may be due to degradation products.     

Leatherwork: a possible hazard to reproduction.

A retrospective study was carried out aimed at eliciting the causes of perinatal death in Leicestershire between 1976 and 1982. Case notes were reviewed and the mothers interviewed in over 1000 cases. An analysis of maternal occupations showed that leatherworkers were at increased risk of having a perinatal death, particularly from congenital malformations and macerated stillbirths, even when compared with other manual workers in the same social class. The excess risk occurred in all towns of the county where leatherwork was undertaken. Further investigation is needed of the materials used in the leather industry in order to ensure that risks are minimised. Fecund women working in the industry should be informed of any residual risk if these findings are confirmed.     

Eighteen years of saturation tagging data reveal a significant increase in nesting hawksbill sea turtles (Eretmochelys imbricata) on Long Island, Antigua

Hawksbill sea turtle Eretmochelys imbricata nesting on Long Island, Antigua, West Indies (also known as Jumby Bay) has been monitored since 1987. Although the numbers of nesting females remained relatively constant for the first 11 survey seasons (1987–1997), inclusion of more recent data (1998–2004) in the analysis reveals a statistically significant upward trend. In particular, neophytes have shown a significant upturn in numbers, whereas the remigrant subpopulation has remained stationary. This indicates that recruitment is driving the upward trend in the total number of nesters. Predictive models based on the Poisson distribution suggest that the neophyte subpopulation will continue to grow in size by an average of 10% per annum. Model-based predictions and their limitations are discussed. The Jumby Bay Hawksbill Project, which has monitored and protected nesting hawksbills and their eggs since the project's onset, is one among several factors that may contribute to the recent increase in nesting females.     

Polycystic ovary syndrome: interaction of follicle stimulating hormone and polypeptide growth factors in oestradiol production by human granulosa cells

The mechanism of the ovarian dysfunction in polycystic ovary syndrome, the most common cause of anovulatory infertility, remains obscure. Clinical data suggest that follicle stimulating hormone (FSH) action may be inhibited at the ovarian level by paracrine factors derived, presumably, from interstitial cells. The greater responsiveness to FSH of granulosa cells isolated from polycystic ovaries (PCO) compared with that seen in cells derived from normal ovaries, provides some support for this hypothesis and we present data which suggests that epidermal growth factor, or more likely transforming growth factor alpha, could be a candidate for this inhibitor. It should be emphasized, however, that the cardinal biochemical feature of the PCO is hypersecretion of androgens by interstitial cells. Stromal tissue from the PCO will secrete significant quantities of androstenedione in response to LH, whereas there is a negligible response in stroma from normal ovaries. It remains to be determined whether androgens have a direct inhibitory effect on FSH-induced oestradiol production in the human follicle, or whether they might exert an indirect effect by activating inhibitory polypeptide growth factors.     

Trace-element budgets in the Ohio/Sunbury shales of Kentucky: Constraints on ocean circulation and primary productivity in the Devonian–Mississippian Appalachian Basin

The hydrography of the Appalachian Basin in late Devonian–early Mississippian time is modeled based on the geochemistry of black shales and constrained by others' paleogeographic reconstructions. The model supports a robust exchange of basin bottom water with the open ocean, with residence times of less than forty years during deposition of the Cleveland Shale Member of the Ohio Shale. This is counter to previous interpretations of these carbon-rich units having accumulated under a stratified and stagnant water column, i.e., with a strongly restricted bottom bottom-water circulation. A robust circulation of bottom waters is further consistent with the palaeoclimatology, whereby eastern trade-winds drove upwelling and arid conditions limited terrestrial inputs of siliciclastic sediment, fresh waters, and riverine nutrients. The model suggests that primary productivity was high (~ 2 g C m^− 2 d^− 1), although no higher than in select locations in the ocean today. The flux of organic carbon settling through the water column and its deposition on the sea floor was similar to fluxes found in modern marine environments. Calculations based on the average accumulation rate of the marine fraction of Ni suggest the flux of organic carbon settling out of the water column was approximately 9% of primary productivity, versus an accumulation rate (burial) of organic carbon of 0.5% of primary productivity. Trace-element ratios of V:Mo and Cr:Mo in the marine sediment fraction indicate that bottom waters shifted from predominantly anoxic (sulfate reducing) during deposition of the Huron Shale Member of the Ohio Shale to predominantly suboxic (nitrate reducing) during deposition of the Cleveland Shale Member and the Sunbury Shale, but with anoxic conditions occurring intermittently throughout this period.     

Changes in regional cerebral metabolism during systemic hyperthermia in humans.

Whole body hyperthermia may produce vasodialation, nausea, and altered cognitive function. Animal research has identified brain regions that have important roles in thermoregulation. However, differences in both the cognitive and sweating abilities of humans and animals implicate the need for human research. Positron emission tomography (PET) was used to identify brain regions with altered activity during systemic hyperthermia. Human subjects were studied under cool (control) conditions and during steady-state hyperthermia induced by means of a liquid-conditioned suit perfused with hot water. PET images were obtained by injecting [(18)F]fluorodeoxyglucose, waiting 20 min for brain uptake, and then scanning for 10 min. Heating was associated with a 23% increase in resting metabolic rate. Significant increases in cerebral metabolic rate occurred in the hypothalamus, thalamus, corpus callosum, cingulate gyrus, and cerebellum. In contrast, significant decreases occurred in the caudate, putamen, insula, and posterior cingulum. These results are important for understanding the mechanisms responsible for altered cognitive and systemic responses during hyperthermia. Novel regions (e.g., lateral cerebellum) with possible thermoregulatory roles were identified.     

Response to novelty inSaimiri andCallicebus: Influence of social context

Responses to novel objects by pair-livingSaimiri andCallicebus and grouplivingSaimiri were investigated in two experiments. In the first, titis and squirrel monkeys were tested in the presence and absence of an opposite-sexed pairmate. The species were differentially affected by the absence of the pairmate: titis of both sexes were distressed and object interest was attenuated; squirrel monkeys were not distressed and object scores (particularly females') increased. Nonsocial differences in object exploration principally involved the tempo and mode of investigation; squirrel monkeys were quicker and more vigorous than titis. In the second experiment, presence of a novel object was found to attract and arouse grouplivingSaimiri, as indicated by the change in the frequency and nature of social interactions and spatial distribution. Within- and between-sex social interactions reflected the typical female nucleus-peripheral male pattern seen inSaimiri groups in other environments. Species differences in investigatory patterns were considered to be contributing elements in the maintenance of distinctive life-styles.     

Quantitative studies of phagocytosis by alveolar macrophages

The initial rate of phagocytosis by rabbit alveolar macrophages of paraffin oil emulsions stabilized with albumin was markedly increased by prior incubation of the emulsion with serum. The active component(s) of serum was non-dialyzable and heat-labile and was absent from zymosan-treated serum. Magnesium and calcium were both required for the maximal rate of phagocytosis. At 4 °C or in the presence of 1 mM N-ethylmaleimide, the rate of phagocytosis was less than 2% of the control (37° C) rate. The initial rates of phagocytosis of this emulsion by alveolar macrophages from rabbits injected with Freund's adjuvant were not demonstrably different from those observed with macrophages from normal rabbits. Per of mg of cell protein, polymorphonuclear leukocytes ingested serum-treated emulsion more rapidly than did macrophages, but per cell the rates were not different.