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Biomedical subjects

J Wilson

Publications and source records attributed to J Wilson.

At least 379 records · Page 21Linked to original sources
PubMed1994

Ligament tension affects nuclear shape in situ: an in vitro study.

This study was carried out to test the hypothesis that a relationship exists between ligament tension and ligament cell geometry. Rabbit knee joints were positioned at 70 degrees of joint flexion and the medial collateral ligament (MCL) was mechanically isolated and the femur-MCL-tibia complex was stretched or compressed by displacing the crosshead of a materials testing machine: -2.0 mm (relative compression), 0.0 mm (a reproducible no-load starting point), +/-0.7 mm or + 1.4 mm (relative tension). Each MCL complex was then fixed immediately in 10% neutral buffered formalin. Contralateral knees were dissected similarly with MCLs exposed and fixed in situ at 70 degrees of flexion. Subsequent to histological processing, measurements were made of the profiles of fibrocyte nuclei (since previous work has shown that nuclear shape closely approximates fibrocyte shape) that were located in the central portion of each MCL midsubstance using a video-based computerized morphometry system. Results showed that the dimensions of nuclei in the midsubstance of experimental MCLs were significantly longer and thinner at crosshead displacements that corresponded to increased ligament tension. At +1.4 mm of displacement fibrocyte nuclei were approximately 4 microm longer and 1 microm thinner than those fixed at 0.0 mm, an observation supported by a statistically significant increase in the mean maximum-to-minimum-diameter ratio and a significant decrease in mean cell roundness. These results strongly suggest that mechanical load can directly affect ligament fibrocyte geometry in situ. If a similar phenomenon also occurs in vivo, the metabolism of ligament fibrocytes may be influenced considerably by their loading history.

Animals↗
PubMed1994

Alcohol levels in tissue conditioners: high enough to fail the breathalyser?

Most tissue conditioners contain ethanol, but only a very small amount would be present in any application. An investigation was carried out to see if the levels of alcohol effusing from freshly applied conditioners would register on an intoximeter of the type used by police to breathalyse drivers suspected of drinking alcohol. The conditioners were applied to the complete dentures of six edentulous subjects who were then breathalysed at intervals after application. There was sufficient alcohol vapour present to register on the intoximeter in all cases and, for one conditioner, the levels immediately after application were high enough to fail the breathalyser test!

Acrylic Resins↗
PubMed1994

Adenovirus vector-mediated in vivo gene transfer into adult murine retina.

PURPOSE: To determine whether a reporter gene can be introduced into the adult mammalian retina in vivo through means of a recombinant replication-deficient adenovirus. METHODS: A dilution series of purified Ad.CMVlacZ ranging from 10(5) to 10(11) pfu/ml was prepared and microinjected into the subretinal space of adult CD-1 mice. This virus contained the cytomegalovirus (CMV)-promoted Escherichia coli reporter gene, lacZ. LacZ expression was assessed in enucleated eyes from 0 to 95 days after injection by beta-galactosidase (beta-Gal) assay. RESULTS: The efficiency of transfection increased as a function of concentration of recombinant virus injected. Eyes injected with greater than 10(7) pfu of Ad.CMVlacZ demonstrated beta-Gal activity lasting at least 95 days. LacZ expression was apparent only in those cells directly exposed to the adenovirus. LacZ expression was observed in the retinal pigment epithelium (RPE) at high efficiency at 48 hours after exposure. By 2 weeks after injection of > 10(7) pfu, lacZ was also expressed in photoreceptors, but at lower density. CONCLUSIONS: These results demonstrate that high efficiency stable transfer of functional genes can be achieved in vivo in post-mitotic mammalian retina using recombinant adenoviral vectors. Adenovirus vectors appear to be a promising means for delivering therapeutic genes in vivo to the mammalian neural retina and particularly to the RPE.

Adenoviruses, Human↗
PubMed1993

Heterogeneity of dermal microvascular endothelial cell antigen expression and cytokine responsiveness in situ and in cell culture.

Microvascular endothelial cells (EC) recruit circulating leukocytes at sites of inflammation, in part through cytokine-regulated expression of endothelial-leukocyte adhesion molecules. Adhesion molecule expression varies among vascular beds and among EC within microvessels of a particular vascular bed. In the present study, we have examined the patterns of antigen expression and cytokine responsiveness of dermal microvascular endothelial cells (DMEC) in a skin organ culture model and, for comparison, in cell culture. Within the superficial vascular plexus (SVP) of normal skin, CD36 molecule expression is undetectable on capillary loops and is expressed on DMEC in only 20% of the larger, horizontal vessels. CD36 expression is not modulated by cytokines. Endothelial-leukocyte adhesion molecule-1 (ELAM-1) expression induced at 6 and 24 h by TNF or IL-1, is restricted to the venular side of the capillary loop and to the venules proper. Vascular cell adhesion molecule-1 (VCAM-1) expression is not inducible on EC of the SVP in normal skin by TNF, IL-1, or IL-4, alone or in combination at either time point. When inflamed skin is examined in organ culture, SVP EC are cytokine responsive regarding VCAM-1 expression. Within the deep vascular plexus (DVP). CD36 molecules are expressed on EC in all capillaries and small vessels. Both ELAM-1 and, to a lesser extent, VCAM-1 expression are inducible by TNF, IL-1, and/or IL-4 on capillaries and larger microvessels at 6 and 24 h. The larger vessels at the dermal-subcutaneous border were found to be CD36-/ELAM-1+/VCAM-1+ after cytokine treatment. CD36 expression of DMEC in cell culture varies from 47 to 98% of cells (mean 75%) in seven separate isolates and is not modified by cytokines. Upon TNF or IL-1 activation, 50 to 90% of DMEC express ELAM-1 molecules at 6 h and expression persists at high levels for 24 h. VCAM-1 expression is negligible at both times. These results with DMEC differ from human umbilical vein EC analyzed in parallel, which are completely CD36- and show transient ELAM-1 and sustained VCAM-1 expression in response to TNF and IL-1. In summary, we have demonstrated that DMEC comprise a heterogeneous population that differ from umbilical vein EC.

Animals↗
PubMed1993

Association of the A subunits of recombinant placental factor XIII with the native carrier B subunits from human plasma.

Interactions of a recombinant human placental protein (rA2) expressed in yeast and considered to be identical to the catalytic A2 subunits of factor XIII, the fibrin stabilizing factor zymogen, were examined with the native carrier subunits (B2) of the factor isolated from human plasma. Nondenaturing electrophoresis and HPLC gel-filtration experiments showed a tight binding of rA2 to B2 for forming an ensemble similar to that of plasma factor XIII (A2B2). In the presence of excess B2, however, some higher ordered oligomers (rA2Bn, where n > 2) were also seen in electrophoresis. The same technique revealed a microheterogeneity in the rA2 preparation; nevertheless, all isoforms could bind to B2. By employing an ELISA procedure for measuring free B2 in mixtures with rA2, an apparent binding constant of 4 x 10(7) M-1 was derived for the association of rA2 with B2. Fluorescence depolarization was used to monitor the heterologous association of rA2 with fluorescein-labeled B2F as well as the dissociation of the rA2B2F structure. The former was characterized by an increase, and the latter by a decrease, in the fluorescence anisotropy of the system. Binding of rA2 to B2F (pH 7.5, mu = 0.315, 37 degrees C) was not influenced by low concentrations of Ca2+ (< or = 30 mM), and rA2B2F proved to be quite stable under these conditions. Much higher concentrations of Ca2+, as well as higher ionic strengths, were required to dissociate this assembly. By contrast, release of B2F from the thrombin-modified rA2'B2F occurred rapidly in the presence of low concentrations of Ca2+ at low ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1993

Signal transduction pathways mediating mucin secretion from intestinal goblet cells.

Cholinergic stimulation of the HT29-18N2 goblet cell line increased mucin secretion as assessed: (1) with a mucin-specific immunoassay, (2) using whole-mount immunocytochemistry, or (3) by morphometric quantification of intracellular mucous granule stores. Cholinergic stimulation did not, however, result in the apical plasmalemmal membrane cavitation that is characteristic of recent compound exocytotic activity. The response was not dependent on protein kinase C activation since it was not inhibited by the kinase C antagonist H7 or potentiated by the diacylglycerol kinase antagonist R59022. Calcium ionophore A23187 also accelerated mucin secretion by a noncompound exocytotic pathway. Activation of protein kinase C by phorbol 12-myristate 13-acetate, on the other hand, increased mucin secretion by a compound exocytotic pathway. The results provide insight into the signal transduction pathways underlying secretory responses of goblet cells observed in situ.

Adenocarcinoma↗
PubMed1993

Morphometric analysis of mucous granule depletion and replenishment in rat colon.

Computer-assisted morphometric analysis was used to quantify mucous granule discharge and the subsequent replenishment of secretory granules in the rat colon following cholinergic challenge. Within 5 min of stimulation (250 micrograms/kg carbachol, subcutaneous), the volume of intracellular mucous granules decreased to 61.5% of the control. The apical plasma membranes of goblet cells in the midcrypt region became deeply cavitated, indicating that they had accelerated mucous granule secretion by a process of compound exocytosis. Goblet cells at the base of the crypt rarely showed cavitated apical membranes but clearly became depleted of intracellular mucous granules. At 60 min after stimulation, cavitated profiles were very rare (< or = 0.4%) but intracellular stores of mucous granules were still significantly depressed (54.7% of control). By 4 hr after stimulation, mucous granule stores recovered to 94.9% of control levels. Morphometric quantification was found to be a reliable and sensitive measure of recent goblet cell secretory activity.

Animals↗
PubMed1993

Norepinephrine release in rat vas deferens. Effect of rauwolscine and BHT 920.

Norepinephrine (NE) overflow from field-stimulated rat was deferens preparations was quantified directly by electrochemical detection using high performance liquid chromatography. The effect of agonist (BHT 920) and antagonist (rauwolscine) of prejunctional alpha 2-adrenoceptors on NE overflow was assessed and compared with their effect on the smooth muscle mechanical response to field stimulation. Increasing the stimulation frequency from 2 to 30 Hz resulted in an increase in muscle tension together with an increase in NE overflow. Addition of 1 microM rauwolscine to the medium resulted in a significant increase in muscle contraction to field stimulation which reached a maximum at 5 Hz. On the other hand, NE overflow increased linearly with the frequency of stimulation within the range studied. Addition of 0.1 microM BHT 920 to the medium significantly decreased the amplitude of contractions at lower stimulation frequencies (2 to 10 Hz) but elicited no significant changes at high frequencies. BHT 920 did not significantly affect NE overflow for all range of stimulation frequency. The simultaneous recording of field-stimulation induced contractions and NE overflow indicates that in the rat vas deferens, rauwolscine acts like a pure alpha 2 adrenoceptor antagonist at a prejunctional level. BHT 920 did not appear to affect selectively prejunctional alpha 2 adrenoceptors but also may activate postjunctional alpha 1 adrenoceptors.

Adrenergic alpha-Agonists↗