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Biomedical subjects

M Castel

Publications and source records attributed to M Castel.

At least 37 records · Page 2Linked to original sources
PubMed1983

[Digestive endometriosis: a diagnostic pitfall not to be ignored].

Seven selected cases illustrate the problems which arise in the diagnosis and management of digestive endometriosis. The site is variable but the rectosigmoid region is most commonly involved. Digestive endometriosis, which is often mistaken for intestinal carcinoma, may have various clinical presentations: latent form discovered during laparotomy, subacute intestinal obstruction, acute abdominal syndrome, or cyclic gynecologic or digestive symptoms. Finally, the therapeutic means of curing these patients and avoiding unnecessary extensive intestinal resection are discussed.

Adult↗
PubMed1983

Changes in hypothalamic and extra-hypothalamic vasopressin content of water-deprived rats.

A correlative radioimmunoassay (RIA) and immunocytochemical (ICC) study was carried out on vasopressin (VP) distribution and content in brains of normal and 3-day water-deprived rats. By RIA there were statistically significant differences in brain VP per pg/mg between normal and osmotically stressed specimens in hypothalamus (338.4 versus 134.4), thalamus (4.8 versus 0.9), septum (18.0 versus 3.4), striatum (1.6 versus 0.7) and amygdala (17.3 versus 1.3), but not in other brain regions measured. Pituitary VP decreased from 71.1 to 8.7 ng/mg, and plasma VP rose from 3.6 to 19.3 pg/ml during water deprivation. Application of the peroxidase-anti-peroxidase ICC method of Sternberger to vibratome sections showed that VP-immunoreactivity in dehydrated specimens decreased in perikarya of paraventricular nucleus and suprachiasmatic nucleus, while intrahypothalamic immunoreactive magnocellular fibers appeared more conspicuous due to proliferation of large Herring bodies. In extrahypothalamic sites VP-immunoreactivity in water-deprived rats was visibly reduced in periventricular thalamus and septum. Thus it is apparent that both intra- and extrahypothalamic VP are affected by osmotic stress, and these results are discussed within the context of current ideas relating to co-activation of neurosecretory cells that project to different sites.

Animals↗
PubMed1982

Kinetics of the inhibition of plasmin in acidified human plasma.

Acid-treated human plasma is a competitive inhibitor of the hydrolysis of D-Val-Leu-Lys-Nan (S-2251) by plasmin. The rate of hydrolysis is decreased to 50% by 750 fold diluted acidified normal plasma and by 60 fold diluted acidified alpha 2-antiplasmin depleted plasma (alpha 2-antiplasmin concentration less than 2%). These findings suggest that alpha 2-antiplasmin is a contributary but not the main competitive inhibitor of acidified plasma. This interpretation is supported by the finding that alpha 2-antiplasmin depleted plasma reconstituted with purified alpha 2-antiplasmin inhibits the hydrolysis of S-2251 by plasmin at a 125 fold dilution following acidification and by the finding that in a purified system acid inactivated alpha 2-antiplasmin inhibits the hydrolysis of S-2251 by plasmin with a Ki of 25 nM. Thus, besides alpha 2-antiplasmin, other plasma proteins which are at least in part eliminated by the removal of alpha 2-antiplasmin from plasma by immunoadsorption appear to be competitive inhibitors for plasmin in acidified plasma. It is suggested that several competitive inhibitors for plasmin are present and/or generated in acidified plasma and that these inhibitors may at least in part be responsible for the variability in the results of measurements of plasminogen and/or plasmin in plasma following acidification.

Fibrinolysin↗
PubMed1982

Comparative study of the activity of high and low molecular weight urokinase in the presence of fibrin.

The fibrinolytic or thrombolytic activity of low molecular weight urokinase (LMW-UK) and high molecular weight urokinase (HMW-UK) is not significantly different when measured in a bovine fibrin plate method, in a circulating plasma system containing a 125I-labelled human fibrin clot, or on 125I-fibrin films in culture plates using normal or alpha 2-antiplasmin depleted human plasma. In a human fibrin plate method however HMW-UK was found to be more active than LMW-UK. In a purified system on human 125I-fibrin films the activation of native or modified human plasminogen by HMW-UK was also found to be more effective than by LMW-UK. Using a clot lysis test system we did not observed a different inhibition of LMW-UK and HMW-UK upon incubation in human plasma. This is in contrast with previous reports that HMW-UK is inhibited more rapidly in human plasma than LMW-UK. In a purified system the inhibition rate of LMW-UK and HMW-UK by alpha 2-antiplasmin is the same (rate constants at 25 degree C of 167 +/- 9 M-1s-1 and 171 +/- 5 M-1s-1 respectively). The clinical trials available at present used doses of urokinase which were in excess of those required to obtain a maximal fibrinolytic effect. This might explain why in these trials no difference was observed between the thrombolytic effect of LMW-UK and HMW-UK, while in vitro HMW-UK appeared to be more effective. However, one should always be careful to extrapolate in vitro observations as such to the in vivo situation encountered during thrombolytic therapy.

Animals↗
PubMed1982

Tubuloreticular structures in S49 cells. Relation to cAMP-dependent protein kinase.

Tubuloreticular structures (TRS) occur spontaneously in S49 mouse lymphoma cells grown in suspension culture. These structures appear in approx. 20% of the cells in electron microscopical cross-sections. Cloning of S49 cells in semi-solid agarose reveals that TRS are potentially present in all S49 cells. An increase of 60% in the frequency of TRS was observed following exposure of S49 cells to 2 X 10(-4) db-cAMP. This increase was not observed in mutant S49 cells lacking cAMP-dependent protein kinase activity. The data suggest that one possibility for the regulation of TRS is through a pathway involving cAMP-dependent protein kinase. In addition, TRS also appear in tumors derived from S49 cells and therefore serve as an ultrastructural cytoplasmic marker for these cells, both in culture and in syngeneic hosts. We suggest the S49 cells as a model system for studying the regulation and function of tubuloreticular structures in vitro and in vivo in malignant lymphoid cells.

Animals↗
PubMed1980

Thiamine pyrophosphatase activity in the axonal smooth endoplasmic reticulum of neurosecretory neurons.

Neurosecretory cells of the supraoptic-neurohypophysial system of normal mice were investigated with the use of the cytochemical reaction for thiamine pyrophosphatase (TPPase) at the ultrastructural level. In the hypothalamic perikarya dense lead percipitates occur within the cisterns of the mature face of the Golgi apparatus, these being the cisterns that give rise to neurosecretory granules (NSG). Smooth endoplasmic reticulum is occasionally confluent with TPPase-positive Golgi cisterns. Along axons, within swellings, and within terminals distinct profiles of TPPase-positive tubules and cisterns are revealed, apparently part of a network of axonal smooth endoplasmic reticulum (AER). Some NSG appear to be confluent with AER. NSG with TPPase-positive tubular protrusions (likely vestiges of AER) are seen. Apart from reaction product (lead precipitate), the AER often contains an electron dense substance optically similar to that of NSG. TPPase-containing AER is often associated with mitochondria. Profiles of electron-lucent, precipitate-free tubules and cisterns are occasionally seen alongside reactive AER. Optimal TPPase activity in the AER occurs at pH 7.0--7.4, whereas in the Golgi complex intense marking is in the range of pH 6.0--8.5. A faint peppering of precipitate occasionally appears in the AER in controls (incubation medium without substrate), but neither in density nor in extent is this comparable to the reaction product seen after incubation in the presence of TPP. Preliminary comparison has been made between the AER revealed by the TPPase reaction, and that visualized after heavy metal impregnation according to the method of Alonso and Assenmacher (1978a). The nature of the close association between NSG and AER, and the possible roles of this membrane system in neurosecretory cells is discussed.

Animals↗
PubMed1978

Non shivering thermogenesis and implication of the thyroid in cold labile and cold resistant populations of the golden spiny mouse (Acomys russatus).

The golden spiny mouse is dependent on non shivering thermogenesis (N.S.T.) for thermoregulation at cool ambient temperatures. Mice from the shores of the Dead Sea (Ein-Gedi, EG-mice) lose body heat when exposed to 6 degrees C. Their rate of cooling is linearly correlated to the magnitude of N.S.T. This is true for mice acclimated to 28 degrees C, born in the laboratory or freshly captured. Mice from the high mountains of South Sinai (S-mice) resist cooling under the same conditions and their N.S.T. is about twice that of EG-mice. EG-mice did not acclimate to cold. However thyroxine injections made them cold resistant and their N.S.T. rose to values close to that of S-mice. Light and electronmicroscopy of the thyroids in mice acclimated to 28 degrees C and exposed to 6 degrees C, or injected with TRH suggested intense activity in S-mice and little activity in EG-mice.

Acclimatization↗
PubMed1978

Immunocytochemical evidence for vasopressin receptors.

An electron microscopic study was made of mouse pituitaries immunocytochemically stained with anti-lysine vasopressin (LVP) as the primary antiserum in the unlabeled antibody peroxidase-anti-peroxidase procedure. Vasopressin (VP) was identified in the neurosecretory granules of the neural lobe which stained with peroxidase anti-peroxidase molecules. Electron density was induced in secretory granules of the pars intermedia (PI), both in the melanocyte stimulated hormone and ACTH cell types, probably indicating VP molecules attached to binding (receptor) sites. Omission of anti-LVP abolished staining both in the neural lobe and the PL Anti-LVP absorbed with antigen, by admixing with LVP, abolished staining in the neural lobe but not in the PI; according to optical density measurements the PI showed a +/- 22% staining increase over controls. Staining intensity in the PI probably reflects occupancy of binding (receptor) sites for VP. Exposure of PI granules to LVP before the usual staining sequence resulted in +/- 48% increased staining. In water-deprived mice with high endogenous VP titers, staining was +/- 33% and +/- 40% more intense than in normal mice. Solid phase absorbed and eluted antibodies to LVP provided additional proof that staining in both neural lobe and PI could be attributed to anti-LVP. Results indicate that binding or receptor sites for VP are located on secretory granules in the PL Possible physiological significance is discussed.

Animals↗
PubMed1977

Pseudopodia formation by neurosecretory granules.

Ultrastrucal studies of the mouse neurohypophysis, under various experimental conditions, revealed a number of neurosecretory granules (NSG) bearing single pseudopodia-like protrusions. Some NSG adhered to the axolemma via pseudopodia; other NSG, distant from the axolemma, budded electron lucent microvesicles from the tip of the pseudopod. Pseudopodia counts were made on electron micrographs, and calculated as a percentage of the NSG population. In neural lobes from intact mice, small numbers of pseudopodia were observed (0.3%); the count increased significantly after injections of large doses of horseradish peroxidase (HRP) (9.4--14.5%); hypertonic saline augmented the count, as did histamine. In vitro incubation experiments with isolated neural lobes in Krebs Ringer revealed concomitant pseudopodia formation and elevated vasopressin release (measured by antidiuretic bioassay) in the presence of HRP and di-butyryl cyclic AMP respectively. Histamine and excess potassium also increased hormone secretion, but did not induce pseudopodia formation in vitro; pseudopodia were observed neither in controls, nor in the presence of ineffective secretagogues. It is suggested that the pseudopod may represent the active site on the granule membrane. Different ultrastructural images of granule release suggest that several modes of hormone release may be operative in the neurohypophysis. The role of HRP in pseudopodia formation and vasopressin release is enigmatic.

Animals↗
PubMed1976

Ultrastructural immunohistochemical localization of vasopressin in the hypothalamic-neurohypophysial system of three murids.

Vasopressin was immunohistochemically localized at the electron microscopic (EM) level in the hypothalamic-neurohypophysial system (HNS) of three murids. Antiserum to vasopressin was produced in rabbits injected with lysine vasopressin (LVP) conjugated to egg albumin (EA), anti-EA being precipitated prior to staining. Sternberger's unlabeled antibody peroxidase technique was employed, immunoreactivity being designated by peroxidase-anti-peroxidase (PAP) molecules and electron opacity. Immunoreactive neurosecretory granules (NSG) were found in the perikarya of the supraoptic nucleus (SON) in all three murids investigated, although far more profusely in the two wild strains. Immunoreactive axonal NSG were observed in the inner and outer zones of the median eminence (ME), and within most of the axons and terminals in the neurohypophysis. The concentration of primary serum effective for staining the SON (1:10-1:50) was far higher than that required for the ME and the neurohypophysis (1:500-1:1,200). Anti-LVP also induced electron opacity of granules in cells of the pars intermedia (PI). Discussion centers of the significance of immunoreactive NSG in the neurosecretory (NS) perikarya, on the possibility of an extragranular pool of hormone, and on speculation about the electron opacity of the PI granules.

Animals↗
PubMed1976

Ultrastructure of region of a low safety factor in inhomogeneous giant axon of the cockroach.

1. The structure of the ventral giant axons of the cockroach at the level of ganglion T3 was studied by means of light and electron microscopy. 2. From serial sections and cobalt injections, the axons diameter was found to range between 40 and 60 mum at the caudal end of ganglion T3; toward the center of T3 they narrow to 20-40 mum, and again expand to 30-45 mum anteriorly in ganglion T3. 3. Each giant axon sends off several branches, 1-15 mum in diameter, into the neuropil. The giant axons and the bases of their branches are enveloped by cytoplasmic processes of glial cells. The periaxonal space is about 100-200 A. 4. Distally the branches are devoid of glial envelopes and the extracellular space between the branches and other axonal profiles is about 200 A. Terminals with presumptive chemical synapses on the giant axon branches were found. Clear vesicles, 300-400 A in diameter, are seen clustered together. The width of the supposedly synaptic gap is about 100 A. 5. In some areas the branches and other axonal profiles form close appositions.

Animals↗
PubMed1975

The ultrastructure of normal and glycerol treated muscle in the ghost crab, Ocypode cursor.

The ultrastructure of normal and glycerol treated fibers of the closer muscle of the ghost crab, Ocypode cursor, was studiedmthe muscle is composed of presumably phasic (short sarcomeres) and tonic (long sarcomeres) fibers, the latter greatly predominating. Horseradish peroxidase (HRP) was used as an extracellular tracer to delineate the tubular system (TS), and to determine to what extent this system becomes detached from the extracellular space as a result of glycerol treatment. Sarcolemmal clefts invade deeply into the muscle at Z-lines and I-bands; tubules invaginate into the muscle from the clefts and from the surface sarcolemma at the Z-lines, A-I overlaps and A-bands. A tubules are in frequent diadic or tetradic contact with the sarcoplasmic reticulum (SR), whereas Z tubules appear to be randomly associated with SR, terminal cisterns (TC) and Z-line fibrils. When HRP was administered to normal muscle, black reaction product was found adjacent to the outer surface of the sarcolemma, within the clefts and within profiles of the TS throughout the tissue. In glycerol treated muscle peripheral vacuolation frequently occurred; black reaction product penetrated only as far as the vacuoles and into dilated Z-line tubules, but was virtually absent from the rest of the TS. This lack of continuity between the extracellular space and the A tubules indicated disruption or constriction of the A tubules as a result of glycerol treatment, although Z tubule contact with the extracellular space appeared unimpaired. These findings provide ultrastructural correlates of the electrophysiological changes produced by glycerol treatment of the closer muscle of the ghost crab (Papir, 1973), namely, interference with excitation-contraction (e-c) coupling. The random association of the Z tubules with SR and TC, and their resistance to disruption by glycerol treatment, tend to endorse the claims that the Z tubules in crustacean muscle are not directly involved in e-c coupling (Brandt et al., 1965; Peachey, 1967; Selverston, 1967).

Animals↗