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981.
Cranial morphology and adaptations in Eocene Adapidae. II. The Cambridge skull of Adapis parisiensis
One of the most complete skulls of the early primate Adapis parisiensis is in the collection of the Department of Zoology, Cambridge University. This exceptionally well-preserved male skull, from Quercy in southern France, is important in showing relatively small orbits that are highly convergent, a distinct ethmoid component in the medial orbital wall, very small infraorbital foramina, a well-preserved auditory region with the stapedial canal about twice the diameter of the canal for the promontory artery, and a well-preserved braincase 8.8 cm3 in endocranial volume. The frontal lobe of the brain in the Cambridge skull described here is less expanded than that reported previously in a British Museum skull. The average body weight of Adapis parisiensis is estimated to have been about 2.0 kg, and that of Adapis magnus is estimated to have been about 8.4 to 9.0 kg. The encephalization quotient (EQ) of Adapis parisiensis is estimated to have been 0.45, which is well below the range found in modern prosimians. There is some indication that the size of the foramen magnum has increased with increasing brain size during primate evolution. Adapis parisiensis appears to have been a medium-sized, visually oriented, diurnal, sexually dimorphic arboreal folivore. 相似文献
982.
983.
Enzymatic cleavage prior to antibody incubation as a method for neuropeptide immunocytochemistry 总被引:4,自引:0,他引:4
Summary Five anti-gastrin releasing peptide (GRP) sera have been characterized against GRP, bombesin and related polypeptides spotted on cellulose acetate discs. Antibodies reacting with the C-terminal G-14 sequence of bombesin and the 19–27 sequence of GRP, were detected in all sera. Antibodies directed exclsively against the bombesin unrelated 1–17 sequence of GRP were found only in one serum (R-6902). With parallel immunohistochemical tests only the C-terminal immunoreactivity was detected in endocrine-paracrine cells of the chicken proventriculus, while both immunoreactivities were present in nerve fibres and a few nerve cell bodies of the mammalian gut. The distribution of GRP- and bombesin-like immunoreactive nerves in the gastric mucosa of both pyloric and oxyntic type the submucosal and myenteric plexus along the whole gastrointestinal wall and at sphincter regions is detailed. 相似文献
984.
985.
R.D. Nolan G.J. Dusting J. Jakubowski T.J. Martin 《Prostaglandins & other lipid mediators》1982,24(6):887-902
Cyclo-oxygenase products of arachidonic acid metabolism formed by the pericardium and epicardial surface of dog heart were identified and quantitated by radioimmunoassay after separation by high-pressure liquid chromatography. Pieces of pariental pericardium, of dog, ox and rat, when incubated
produced mainly 6-keto-PGF1α, with lesser amounts of PGE2, PGF2α and thromboxane B2. Biosynthesis of all prostanoids increased during incubation of the pariental pericardium of each species with arachidonic acid, but 6-keto-PGF1α was still the major metabolite. When slices of dog heart were incubated with arachidonic acid (1 μg/ml) the rates of 6-keto-PGF1α formation by the pariental pericardium was much greater than that of the myocardium and endocardium. Epicardial slices appeared to be intermediate in 6-keto-PGF1α formation. The hearts of anesthetized dogs were also irrigated
with Krebs' solution, and during the first 5 min of epicardial irrigation the pericardial fluid leaving the heart again contained high levels of 6-keto-PGF1α, with lesser amounts of the other prostanoids. Addition of arachidonic acid (3 μg/ml) to the irrigating fluid caused an increase in all measured prostanoid levels, although 6-keto-PGF1α remained the predominant metabolite. In contrast, intravenous infusion of isoproterenol selectively increased the release of 6-keto-PGF1α from the irrigated heart. It is concluded that the pericardium and epicardium continuously release prostacyclin into the pericardial fluid, and that the increased release of this substance observed when cardiac workload increases derives mainly from these membranous sources. This raises the interesting possibility that pericardial prostacyclin might influence coronary vascular tone and chemoreflexes which arise from the epicardium during myocardial ischemia. 相似文献
986.
Martin L. Ogletree John A. Oates Kenneth L. Brigham Walter C. Hubbard 《Prostaglandins & other lipid mediators》1982,23(4):459-468
Leukocyte trapping in the pulmonary circulation may be an important component of the lung vascular injury response to endotoxin, but mediators of the pulmonary leukostasis and increased lung vascular permeability are unknown. The leukocyte 5-lipoxygenation pathway of arachidonic acid metabolism yields highly biologically active products including leukotrienes C4 and D4 (formerly slow reacting substance of anaphylaxis) and the potent chemotaxin, leukotriene B4. A major product of 5-lipoxygenation is 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE), for which a sensitive, stable isotope dilution assay employing combined gas chromatography-mass spectrometry is available. This assay was used to test the hypothesis that 5-lipoxygenation products might participate in pulmonary vascular responses to endotoxin. We measured 5-HETE concentrations in lung lymph at three intervals during endotoxemia in unanesthetized sheep. Concentrations of 5-HETE in lung lymph exceeded those in aortic blood plasma. Lymph 5-HETE concentrations increased from 1.7±0.3 (mean ± SEM, N = 7) ng/ml during baseline to peak values of 6.1±1.8 ng/ml (p < 0.05) during the
hours after endotoxemia and preceeding the steady state increased lung vascular permeability response. During the increased permeability steady state from 240 to 270 minutes after endotoxin, lymph 5-HETE concentrations (1.4±0.3 ng/ml) and lymph 5-HETE flow (i.e., 5-HETE concentration x lung lynph flow rate) returned to baseline values. Although these observations are consistent with the hypothesis that 5-lipoxygenation products participate in the pulmonary vascular injury response to endotoxin, lymph 5-HETE concentrations did not correlate with any of the other experimental measurements. It may be only coincidence that the increase in lymph 5-HETE concentrations appeared contemporaneous with the onset of lung vascular injury. 相似文献
987.
Identification of the paromomycin-resistance mutation in the 15 S rRNA gene of yeast mitochondria 总被引:29,自引:0,他引:29
M Li A Tzagoloff K Underbrink-Lyon N C Martin 《The Journal of biological chemistry》1982,257(10):5921-5928
988.
Platelet-derived growth factor is a chemoattractant for vascular smooth muscle cells 总被引:37,自引:0,他引:37
G. R. Grotendorst T. Chang H. E. J. Sepp H. K. Kleinman G. R. Martin 《Journal of cellular physiology》1982,113(2):261-266
In previous experiments (Grotendorst et al, 1981), we showed that platelet-derived growth factor promotes the migration of smooth muscle cells in vitro. Using a "checkerboard" analysis, we now establish that platelet-derived growth factor (PDGF) acts as a true chemoattractant for cultured aortic smooth muscle cells. Other growth factors such as epidermal growth factor, fibroblast growth factor, and insulin are not chemoattractants. The chemotactic response occurs before the initiation of DNA synthesis and is not affected by inhibition of DNA synthesis. Chemotaxis occurs at levels of PDGF lower than required for mitogenesis. RNA and protein synthesis are required for the chemotactic response. As found previously in bacteria and leucocytes, we find that methylation reactions are required for the chemotactic response. The possibility is discussed that PDGF acts in vivo at sites of vascular injury to attract smooth muscle cells from the medial layer to the luminal surface, and is involved in the early stages of the formation of atherosclerotic plaques. 相似文献
989.
Allan S. Schneider Hollis T. Cline Kurt Rosenheck † Martin Sonenberg 《Journal of neurochemistry》1982,37(3):567-575
Abstract: The catecholamine secretory function of a preparation of isolated bovine adrenal chromaffin cells has been further characterized under conditions designed to elucidate the mechanism of calcium channel activation and the possible role of cytoskeletal elements in stimulus-secretion coupling. Three related sets of data were obtained: (1) Differences in kinetics, Ca dependence, strength, and additivity of the secretory response to acetylcholine (ACh) versus excess K; (2) the effects on secretion of the Ca channel-blocking agents, Ni, Mg, and verapamil; and (3) the Ca dependence of vinblastine action on ACh- and K-evoked secretion. The results suggest that a major portion of the Ca influx required for catecholamine release enters the cell via voltage-dependent Ca channels with some additional Ca influx via the ACh receptor channel. Comparison of the present secretion data with corresponding known electrophysiological properties of isolated chromaffin cells provides added evidence for a role of chromaffin cell action potentials in regulation of Ca influx and the secretory response. Elevated Ca concentrations enhanced K-evoked secretion to levels comparable to that of ACh but did not induce a vinblastine block of K-evoked release. This provides further evidence against a role of microtubules in the common exocytosis event per se. However, a role of cytoskeletal elements in directing the movement of secretory granules, or an action of vinblastine at cholinergic receptors, remain distinct possibilities. 相似文献
990.
Martin G. Larrabee 《Journal of neurochemistry》1982,38(1):215-232
Metabolism of [1-14C]glucose and [6-14C]glucose was measured in sympathetic ganglia excised from chicken embryos 12-16 days old and in primary cultures of neurons or nonneurons prepared from these ganglia. Some metabolic rates tended to change with the tissue/medium ratio, so this variable had to be controlled. Less C-6 than C-1 od glucose was put out in CO2 by all three types of preparations, indicating operation of the hexosemonophosphate shunt. The C-6/C-1 ratio was greater for the neuronal cultures and for intact ganglia than for the nonneuronal cultures. The C-6/C-1 ratio for the neurons increased with the amount of tissue added to a given volume of incubation medium, in agreement with previous experiments on embryonic dorsal root ganglia (Larrabee, 1978). Per unit of protein, the output of C-1 of glucose in CO2 was higher in both the neuronal and the nonneural cultures than in intact ganglia, whereas that of C-6 was higher in the neuronal cultures and lower in the nonneuronal ones than in the ganglia. The rates of release in lactate of C-1 and C-6 of glucose were 3-5 times higher from both types of cultures than from intact ganglia. The average rates of incorporation of C-1 and C-6 of glucose into tissue constituents were lower in the cultures than in intact ganglia, significantly so for incorporation of C-6 in the nonneuronal cultures. 相似文献