Computer determination of perfusion patterns in pulmonary capillary networks

Hanger, Christopher C., Robert G. Presson, Jr., Osamu Okada,Steven J. Janke, John J. Watkins, Wiltz W. Wagner, Jr., and Ronald L. Capen. Computer determination of perfusion patterns in pulmonarycapillary networks. J. Appl. Physiol.82(4): 1283-1289, 1997.Individual pulmonary capillaries are notsteadily perfused. By using in vivo microscopy, it can readily bedemonstrated that perfusion continually switches between capillarysegments and between portions of the network within a single alveolarwall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching between capillary segments in the absence of hemodynamic changes in large upstream vessels suggests that capillary perfusion patterns could be random. Tocalculate the probability that perfusion patterns could occur bychance, it is necessary to know the total number of possible perfusionpatterns in a given capillary network. We developed a computer programthat can determine every possible perfusion pattern for any givencapillary network, and from that information we can calculate whetherperfusion of individual segments in the network is random. With theresults of the computer program, we have obtained statistical evidencethat some capillary segments in a network are nonrandomly perfused.

     

Secretion of neurophysins by the ovary in sheep

Measurements of venoarterial concentration differences across the ovary in anesthetized sheep have demonstrated that the ovary secretes ovine neurophysin I/II (oNP I/II) and that this process is stimulated by the prostaglandin F2 alpha analogue, cloprostenol. A parallel increase in the secretion of oxytocin (OT) was observed in response to cloprostenol, and the mean molar ratio of oNP I/II to OT secreted was 1.2. There was no detectable ovarian secretion of oNP III. Secretion of oNP I/II and OT was absent after hysterectomy. The data support other evidence indicating that the corpus luteum synthesizes OT, and confirm that the neurophysin associated with OT in the sheep is oNP I/II.     

Diminished bronchial reactivity to cold air in diabetic patients with autonomic neuropathy.

To investigate the role of neural pathways in the nonasthmatic response to eucapnic hyperventilation with below freezing air five diabetic patients with severe symptomatic autonomic neuropathy were studied. Their responses were compared with those shown by five diabetic patients without autonomic neuropathy and five non-diabetic controls. After bronchial provocation testing with cold air the diabetic patients with autonomic neuropathy did not show a significant fall in specific airways conductance (mean (SE) maximum percentage fall 2.0 (3)%), whereas conductance fell in the diabetic patients without neuropathy by 30.8 (2.0)% (p less than 0.001) and in the non-diabetic controls by 22.7 (4.6)% (p less than 0.02). In subjects who do not have asthma the bronchial response to cold air is mediated largely via neural mechanisms.     

Synthesis and gastrointestinal pharmacology of some 15- and 16- modified (±)-11-deoxyprostaglandins

The synthesis and gastrointestinal pharmacology of some 11-deoxyprostaglandin E₁ analogues are described with results analysed for selectivity from side effects. 11-Deoxygenation reduced potency relative to PGE₂ but, as has been reported for natural PGs, 15- or 16-methyl analogues were more potent than the unsubstituted parent compound in the order 16-methyl > 15-methyl > 16, 16-dimethyl. The results suggest that a complex interaction between C-15 and C-16 in methyl analogues affects their profile of activity, but that none of the modifications studied conferred a substantial potency or selectivity advantage over PGE₂.     

Lipogenesis and the synthesis and secretion of very low density lipoprotein by avian liver cells in nonproliferating monolayer culture. Hormonal effects

The nonproliferating chicken liver cell culture system described yields cell monolayers with morphological and lipogenic properties characteristic of the physiological-nutritional state of donor animals. Synthesis and secretion of fatty acid, cholesterol, and very low density lipoprotein (VLDL) occur at in vivo rates and respond to hormones and agents which affect these processes in vivo. Cells derived from fed chickens maintain high rates of synthesis of fatty acid and cholesterol for several days if insulin is present in the medium. High rates of fatty acid synthesis are correlated with the appearance of membrane-enclosed triglyceride-rich vesicles in the cytoplasm; deletion of insulin causes a decrease (T1/2 = 22 h) in fatty acid synthetic activity. Addition of glucagon or cyclic AMP (cAMP) causes an immediate cessation of fatty acid synthesis and blocks the appearance of the triglyceride-rich vesicles. Fatty acid synthesis in liver cells prepared from fasted chickens is less than 5% that of cells from fed animals. After 2-3 days in culture with serum-free medium containing insulin +/- triiodothyronine, fatty acid synthesis is restored to normal; glucagon or dibutyryl cAMP blocks this recovery. Liver cells derived from estradiol-treated chickens synthesize and secrete VLDL for at least 48 h in culture. Electron micrographs of these cells reveal more extensive development of the rough endoplasmic reticulum and Golgi complex compared to cells from untreated chickens. Whereas [3H]leucine incorporation into total protein is unaffected by estrogen treatment, [3H]leucine incorporation into cellular and secreted immunoprecipitable VLDL is markedly increased indicating specific activation of VLDL apopeptide synthesis; 8-10% of the labeled protein synthesized and secreted is VLDL. Dodecyl sulfate-acrylamide gel electrophoresis of immunoprecipitated 3H-VLDL reveals three major apopepetides of 300,000, 11,000, and 8,000 daltons corresponding to those of purified chicken VLDL.     

Surface lipids of Sphaerotheca fuliginea spores

The major components (50%) of the surface lipid extract of fungal spores (5.6% of dry spore wt) of Sphaerotheca fuliginea are esters of primary alcohols and fatty acids. Esters (15%) of primary alcohols and a Δ^2t acid are present. The major acid moieties of the alkyl esters are C₂₂ and C₂₄ and of the Δ^2t alkyl ester is Δ^2t C₂₂; for both classes eicosanol is the major primary alcohol. The major ester of each class was concluded to be eicosanyl docosanoate and eicosanyl trans-2-docosenoate. Minor components are saturated and Δ^2t methyl and diol diesters and free fatty acids. The major acid moieties of the diol diesters are C₂₂ and C₂₄ and the major diol is 1,12-dodecanediol.     

The subcellular distribution of dystrophin in mouse skeletal, cardiac, and smooth muscle

We use a highly specific and sensitive antibody to further characterize the distribution of dystrophin in skeletal, cardiac, and smooth muscle. No evidence for localization other than at the cell surface is apparent in skeletal muscle and no 427-kD dystrophin labeling was detected in sciatic nerve. An elevated concentration of dystrophin appears at the myotendinous junction and the neuromuscular junction, labeling in the latter being more intense specifically in the troughs of the synaptic folds. In cardiac muscle the distribution of dystrophin is limited to the surface plasma membrane but is notably absent from the membrane that overlays adherens junctions of the intercalated disks. In smooth muscle, the plasma membrane labeling is considerably less abundant than in cardiac or skeletal muscle and is found in areas of membrane underlain by membranous vesicles. As in cardiac muscle, smooth muscle dystrophin seems to be excluded from membrane above densities that mark adherens junctions. Dystrophin appears as a doublet on Western blots of skeletal and cardiac muscle, and as a single band of lower abundance in smooth muscle that corresponds most closely in molecular weight to the upper band of the striated muscle doublet. The lower band of the doublet in striated muscle appears to lack a portion of the carboxyl terminus and may represent a dystrophin isoform. Isoform differences and the presence of dystrophin on different specialized membrane surfaces imply multiple functional roles for the dystrophin protein.