Dietary effects on hematologic and serum chemical values in gray short-tailed opossums (Monodelphis domestica)

At the time of weaning (8 weeks), 57 gray short-tailed opossums (Monodelphis domestica) were placed in four dietary groups. One group was fed a horsemeat-based diet that had been used for 2.5 years in our colony, and three groups were fed three different commercial fox food diets. After the animals had reached sexual maturity (6 months), blood samples were collected and subjected to standard hematologic and serum chemical assays. Significant differences were observed among the dietary groups and between sexes in several values, but all animals appeared to be healthy and robust. The ranges, means, and standard deviations for the values presented here can be used as reference values for healthy young adult animals being fed these particular diets.     

Thoracoabdominal blood volume change and its effect on lung and chest wall volumes

The effects of changing blood volume within the thoracoabdominal cavity (Vtab) have been studied in four male subjects trained in respiratory maneuvers. Subjects were studied lying supine in a pressure plethysmograph with inflatable fracture splints placed around both arms and legs. Changes in Vtab were produced by inflating the splints to 30 cmH2O. Thoracic gas volume (Vtg) measured by Boyle's law, and the change in chest wall volume (delta Vw), measured by anteroposterior magnetometers on rib cage and abdomen, were measured almost simultaneously and at two respiratory system volumes. The quantity of blood moved by splint inflation was estimated for each subject at both respiratory system volumes and varied between 215 and 752 ml. The chest wall increased 64 +/- 11.8% (mean +/- SD) of the increase in Vtab. Thus increases in thoracoabdominal blood volume increase Vw about twice the decrease in Vtg.     

Relationship between diaphragm length and abdominal dimensions

We examined the relationship between changes in abdominal cross-sectional area, measured by respiratory inductive plethysmography, and changes in length in the costal and crural parts of the diaphragm, measured by sonomicrometry, in nine supine, anesthetized dogs. During passive inflation, both parts of the diaphragm shortened and abdominal cross-sectional area increased. During passive deflation, both parts of the diaphragm lengthened and abdominal cross-sectional area decreased. We subsequently used the relationship between costal and crural diaphragmatic length, respectively, and abdominal cross-sectional area during passive inflation-deflation to predict the length changes in the costal and crural diaphragm during quiet breathing before and after bilateral phrenicotomy. In the intact animal the inspiratory shortening in the crural diaphragm was almost invariably greater than predicted from the relationship during passive inflation. During inspiration after phrenicotomy the crural diaphragm invariably lengthened, whereas the costal diaphragm often shortened. In general there was a good correlation between the measured and predicted length change for the crural diaphragm (r = 0.72 before and 0.79 after phrenicotomy) and a poor one for the costal diaphragm (r = 0.05 before and 0.19 after phrenicotomy).     

Perfusion of lung periphery: effects of local exposures to ozone and pressure

Following ozone (O3) exposure, airways reactivity increases. We investigated the possibility that exposure to O3 causes a decrease in pulmonary perfusion, and that this decrease is associated with the increase in reactivity. Perfusion was measured with radiolabeled microspheres. A wedged bronchoscope was used to isolate sublobar segments in the middle and lower lobes of anesthetized dogs. Isolated segments were exposed to either O3 or an elevated alveolar pressure. Although increased alveolar pressure decreased microsphere density, exposure to 1 ppm O3 did not. Collateral system resistance rose significantly following exposure to O3 and to high pressure. These studies do not support the hypothesis that pulmonary perfusion is decreased following O3 exposure and is associated with subsequent increases in reactivity.     

A variant form of the 1,25-dihydroxyvitamin D3 receptor with low apparent hormone affinity in cultured monkey kidney cells (LLC-MK2). A model for tissue resistance to vitamin D

Chandler et al. (Chandler, J.S., Chandler, S.K., Pike, J.W., and Haussler, M.R. (1984) J. Biol. Chem. 259, 2214-2222) previously demonstrated that 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) caused the induction of 25-hydroxyvitamin D3-24-hydroxylase (24-hydroxylase) in a rhesus monkey kidney cell line (LLC-MK2) apparently deficient in the high affinity 1,25-(OH)2D3 receptor. We have re-examined this phenomenon and report here that 24-hydroxylase induction is mediated by a receptor variant in LLC-MK2 cells with low hormone affinity. Dose response analysis showed that in contrast to LLC-PK1 (a typical receptor-positive cell line), the LLC-MK2 line was less sensitive to 1,25-(OH)2D3 by 2 orders of magnitude. Employing optimal concentrations of 1,25-(OH)2D3 for 24-hydroxylase induction in each cell type, the early time courses of this bioresponse were identical in LLC-MK2 and LLC-PK1 and were consistent with a nuclear action of hormone-receptor complexes. Moreover, the rank order of potency of vitamin D3 congeners as inducers of 24-hydroxylase activity in LLC-MK2 cells agreed well with their relative affinity for the 1,25-(OH)2D3 receptor. An examination of 1,25-(OH)2D3 receptor content via DNA-cellulose chromatography in LLC-MK2 cells incubated at ligand concentrations 10-25-fold higher than the normal 2 nM revealed a minimum of 1600 receptor-like molecules/LLC-MK2 cell. These results show that LLC-MK2 cells possess a variant receptor form with apparent low affinity for 1,25-(OH)2D3. This system should serve as a model for clinical syndromes characterized by the requirement for massive doses of vitamin D to prevent rickets.     

Tissue specific expression of p422 protein, a putative lipid carrier, in mouse adipocytes

The differentiation of 3T3-L1 preadipocytes leads to the expression of a new protein, p422, and its mRNA. This protein has 70% and 20-30% amino acid sequence homology to myelin P2 and the fatty acid binding proteins of liver and intestine, respectively. Investigation of the distribution in mouse tissues of p422 protein by immunoblotting and of p422 mRNA by cDNA hybridization indicates that they are expressed only in adipose tissue. Liver and intestinal fatty acid binding protein mRNA's were not detectable in mouse adipose tissue or in 3T3-L1 adipocytes. It is suggested that p422 functions as an adipocyte fatty acid binding protein.     

The response of several murine embryonal carcinoma cell lines to stimulation of differentiation by alpha-difluoromethylornithine

In an attempt to better establish the relationship between polyamine levels and the differentiation of embryonal carcinoma cells, we have examined the ability of alpha-difluoromethylornithine (DFMO), a known inducer of differentiation in one embryonal carcinoma cell line, to stimulate the differentiation of embryonal carcinoma cells from a variety of cell lines. Differentiation was monitored using a variety of criteria including morphological alterations and changes in biochemical and antigenic parameters. Depending on their response to difluoromethylornithine, three classes of cell lines could be identified, those which 1) differentiate extensively, 2) differentiate poorly, and 3) fail to differentiate. Three different classes of embryonal carcinoma cell lines reflect differential changes in polyamine levels resulting from inhibition of ornithine decarboxylase enzyme activity by DFMO. The specific cell lines which exhibit large decreases in both ornithine decarboxylase activity and polyamine levels also show extensive differentiation. The cell lines which show only moderate decreases in enzyme activity and polyamines differentiate poorly while the cell lines which fail to respond to DFMO in that polyamines do not drop below the threshold level necessary to induce differentiation fail to differentiate. These studies suggest that decreases in intracellular polyamines induce EC cell differentiation in vitro.     

Local names for vascular plants in the John Crow mountains,Jamaica

Local names of vascular plants, accompanied by botanical specimens, were collected in the John Crow Mountains, Portland Parish, Jamaica. Each of the names was volunteered by one local informant; many were independently corroborated by others. We recorded 91 names of forest trees and shrubs, 20 names of climbers, and 33 names of other plants. The uneven distribution of local names among different categories of plants is discussed. The names are mostly of English origin, with a scattering from Spanish, Amerindian and West African languages. Many names are not listed in the standard floras; 20 names are apparently hitherto unrecorded in print. The same name was often found to be applied to a different species from the usage given in the floras, showing the variation in vernacular names from one part of the island to another.     

Schistosoma mansoni: complexity of antigenic and nonantigenic surface polypeptides

Two-dimensional gel analysis of the surface polypeptides of the schistosomula stage of Schistosoma mansoni resolved a complex pattern of approximately 20 polypeptides. The majority of these were identified as immunogenic since they were immunoprecipitated with antisera from chronically infected mice and from mice vaccinated with irradiated cercariae. However, several major surface polypeptides were not immunoprecipitated by sera from infected or immune mice and were presumed to be nonantigenic.     

Analysis of the direct effects of prostaglandins on human sperm function

Time-exposure photomicrography and interspecies in-vitro fertilization procedures have been used to examine the influence of prostaglandins on human sperm function. An analysis of variance indicated that the presence of PGs in the incubation media was associated with a significant increase in sperm velocity and the frequency of sperm head rotation, although there were no differences between individual PGs in the degree of stimulation observed. Changes in the penetrating ability of human spermatozoa were detected after exposure to PGs, particularly PGE-1 and PGE-2. PGE-2 induced a sustained increase in penetration rates at all doses of greater than 8.4 micrograms/ml, while exposure to PGE-1 gave a bell-shaped dose-response curve which exhibited a peak between 8.4 and 33.3 micrograms/ml and progressively fell to reach control levels at the maximum concentration tested of 270 micrograms/ml. A combination of PGE-2 and PGE-1 produced a dose-response curve similar to that for PGE-1 alone, while exposure to PGF-2 alpha was without effect. Seminal extracts containing predominantly 19-hydroxy PGE-1, or equal amounts of 19-hydroxy PGE-1 + 2 induced a slight, but significant, rise in penetration rates while a combination of PGs representing the major components of human seminal plasma was without significant effect. We conclude that certain prostaglandins may have a direct action on the functional competence of human spermatozoa.