Search PubMed⌕ Search

Biomedical subjects

J M Anderson

Publications and source records attributed to J M Anderson.

At least 307 records · Page 17Linked to original sources
PubMed1988

Tight junction structure and ZO-1 content are identical in two strains of Madin-Darby canine kidney cells which differ in transepithelial resistance.

The relationship of tight junction permeability to junction structure and composition was examined using two strains of Madin-Darby canine kidney (MDCK) cells (I and II) which differ greater than 30-fold in transepithelial resistance. This parameter is largely determined by paracellular, and hence junctional, permeability under most conditions. When these two strains of cells were grown on permeable filter supports, they formed monolayers with equivalent linear amounts of junction/area of monolayer. Ultrastructural analysis of these monolayers by thin section EM revealed no differences in overall cellular morphology or in tight junction organization. Morphometric analysis of freeze-fractured preparations indicated that the tight junctions of these two cell strains were similar in both number and density of junctional fibrils. Prediction of transepithelial resistance for the two strains from this freeze-fracture data and a published structure-function formulation (Claude, P. 1978, J. Memb. Biol. 39:219-232) yielded values (I = 26.5 omega/cm2, II = 35.7 omega/cm2) that were significantly lower than those observed (I = 2,500-5,000 omega/cm2, II = 50-70 omega/cm2). Consistent with these structural studies, a comparison of the distribution and cellular content of ZO-1, a polypeptide localized exclusively to the tight junction, revealed no significant differences in either the localization of ZO-1 or the amount of ZO-1 per micron of junction (I = 1,415 +/- 101 molecules/micron, II = 1,514 +/- 215 molecules/micron).

Animals↗
PubMed1988

Carbohydrate Metabolism and Activity of Pyrophosphate: Fructose-6-Phosphate Phosphotransferase in Photosynthetic Soybean (Glycine max, Merr.) Suspension Cells.

Activity of pyrophosphate:fructose-6-phosphate phosphotransferase (PFP) was investigated in relation to carbohydrate metabolism and physiological growth stage in mixotrophic soybean (Glycine max Merr.) suspension cells. In the presence of exogenous sugars, log phase growth occurred and the cells displayed mixotrophic metabolism. During this stage, photosynthetic oxygen evolution was depressed and sugars were assimilated from the medium. Upon depletion of medium sugar, oxygen evolution and chlorophyll content increased, and cells entered stationary phase. Activities of various enzymes of glycolysis and sucrose metabolism, including PFP, sucrose synthase, fructokinase, glucokinase, UDP-glucose pyrophosphorylase, and fructose-1,6-bisphosphatase, changed as the cells went from log to stationary phases of growth. The largest change occurred in the activity of PFP, which was three-fold higher in log phase cells. PFP activity increased in cells grown on media initially containing sucrose, glucose, or fructose and began to decline when sugar in the medium was depleted. Western blots probed with antibody specific to the -subunit of potato PFP revealed a single 56 kilodalton immunoreactive band that changed in intensity during the growth cycle in association with changes in total PFP activity. The level of fructose-2,6-bisphosphate, an activator of the soybean PFP, increased during the first 24 hours after cell transfer and returned to the stationary phase level prior to the increase in PFP activity. Throughout the growth cycle, the calculated in vivo cytosolic concentration of fructose-2,6-bisphosphate exceeded by more than two orders of magnitude the previously reported activation coefficient (K(a)) for soybean PFP. These results indicate that metabolism of exogenously supplied sugars by these cells involves a PFP-dependent step that is not coupled directly to sucrose utilization. Activity of this pathway appears to be controlled by changes in the level of PFP, rather than changes in the total cytosolic level of fructose-2,6-bisphosphate.

Journal Article↗
PubMed1988

Effects of thiopentone, etomidate and propofol on the haemodynamic response to tracheal intubation.

The haemodynamic response to tracheal intubation was compared in 303 patients in whom anaesthesia was induced with either thiopentone 4 mg/kg, etomidate 0.3 mg/kg or propofol 2.5 mg/kg, with and without fentanyl 2 micrograms/kg. There was after propofol alone a significant decrease in arterial blood pressure, which did not increase above control values after intubation. Significant increases in arterial pressure followed intubation in patients induced with thiopentone or etomidate alone. Increases in heart rate occurred with all agents after laryngoscopy. The use of fentanyl resulted in arterial pressures lower than those after the induction agent alone, and in an attenuation, but not abolition of the responses to laryngoscopy and intubation.

Adolescent↗
PubMed1988

Evidence that tobacco smoking increases the density of (-)-[3H]nicotine binding sites in human brain.

In a postmortem study of nicotinic receptors in human brain, cigarette smoking was found to be associated with increased (-)-[3H]nicotine binding to membranes prepared from gyrus rectus (Brodmann area 11) (p less than 0.001), hippocampal neocortex (Brodmann area 27), cerebellar cortex (p less than 0.01), hippocampal formation (Ammon's horn + subiculum), and the median raphe nuclei of the midbrain (p less than 0.05) but not the medulla oblongata. Analysis of the binding data suggested that the increased binding reflected an increase in the density of the receptors rather than a change in their affinity for (-)-nicotine. The effects of smoking were not influenced significantly by either the sex or age of the subject. It is concluded that smoking evokes an increase in high-affinity nicotine binding similar to that observed previously in animals treated chronically with nicotine and that the effect of smoking on these sites is probably caused by the nicotine present in the tobacco smoke.

Aged↗
PubMed1988

Hand splinting for infants in the intensive care and special care nurseries.

Infants in intensive care nurseries often have hand deformities and hand dysfunction. The traditional therapeutic approaches to hand care used in the treatment of adults, young children, and older infants are not always adequate to prevent progressive deformity in preterm and neonatal infants. Medical instability, time constraints, lack of family participation in the therapeutic program, the complexity of the treatment program, and fear of harming the infant are considerations that may indicate the need for splinting as an adjunctive therapeutic intervention. A number of factors are particularly important in making splints for infants, including splint alignment and padding, strap attachment, and thermoplastic malleability.

Hand Deformities↗
PubMed1987

Intracellular free calcium in rat anterior pituitary cells monitored by fura-2.

Rat anterior pituitary cells, loaded with the calcium indicator dye fura-2 after primary culture, were challenged with prolactin and growth hormone secretagogues and inhibitory hormones. To initially validate the technique, the calcium channel activator maitotoxin effectively increased intracellular free calcium [( Ca++]i). Various concentrations of the secretagogues thyrotropin releasing hormone or angiotensin II induced peak increases in [Ca++]i within 15 sec, followed by a lower and prolonged plateau phase. The inhibitory hormones dopamine and somatostatin maximally reduced [Ca++]i by 15-20 sec, followed by a spontaneous return to baseline over 5-10 min. The receptor antagonists saralacin and spiperone blocked the angiotensin II and dopamine effects, respectively. Thus, fura-2 appears to be an adequate probe for resolving second-to-second changes in [Ca++]i induced by hormone receptor activation in anterior pituitary cells.

Angiotensin II↗
PubMed1987

Biodegradation of a polyurethane in vitro.

This study examines the effect of in vitro exposure to enzymes on the performance properties of Biomer, a segmented polyetherurethane used in a number of blood-contacting devices such as catheters, heart assist pumps, and chambers for artificial hearts. The ultrathin samples were treated with two proteolytic enzymes, papain and urease, for periods of 1-6 months at 37 degrees C. The treated Biomer samples were subjected to chemical and physical analysis. Effects of biodegradation by the enzymes were assessed by fatigue tests, gel permeation chromatography (GPC), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis. Papain was found to be more effective in degrading the polymer than urease. Mechanisms for enzymic degradation are proposed.

Biodegradation, Environmental↗
PubMed1987

Vascular graft-associated complement activation and leukocyte adhesion in an artificial circulation.

Complement-associated leukocyte adhesion appears to be a consistent in vitro and in vivo finding for many types of polymers; however, very little work has been done on the interaction of leukocytes with vascular graft materials. An in vitro perfusion system was used to study complement and leukocyte activation associated with the following vascular graft materials when tested with human blood: expanded polytetrafluoroethylene (ePTFE), crimped Dacron Bionit (DB) and preclotted Dacron Bionit. A decrease in the total leukocyte concentration with perfusion time was seen for all materials tested, and paralleled leukocyte adhesion to the graft surface as observed by scanning electron microscopy. The most dramatic decrease in leukocyte concentration was observed for the interaction of heparinized whole blood with Dacron. This was due to a selective decrease in neutrophils and monocytes, and was correlated with an increase in both leukocyte adhesiveness and complement activation, as measured by C5a elevation. Inhibiting complement activation by use of the anticoagulant, sodium citrate, curtailed Dacron-induced leukocyte adhesion. Little leukocyte or complement activation was observed for ePTFE or the silicone rubber control regardless of the anticoagulant used.

Adult↗
PubMed1987

In vivo leucocyte interactions with the NHLBI-DTB primary reference materials: polyethylene and silica-free polydimethylsiloxane.

In vivo leucocyte interactions with the NHLBI-DTB primary reference materials, low density polyethylene (LDPE) and silica-free polydimethylsiloxane (PDMS), were qualitatively and quantitatively characterized using a cage implant system over a 21 d implantation period. Scanning electron microscopy (SEM) and cytochemical staining procedures were utilized to observe the cellular events occurring at the leucocyte/biomaterial interface. The results showed that more cells adhered to the PDMS surface than the LDPE surface at days 4 and 7. The differential analysis revealed that mononuclear cells, presumably macrophages, preferentially adhered to both polymer surfaces. By day 21, there were more very large (greater than 20 nuclei per cell) foreign body giant cells (FBGCs) present on the PDMS surface than the LDPE surface. The phagocytic capabilities of the adhered cells, including the FBGCs, decreased to a greater extent on the PDMS surface, corresponding to the earlier and more extensive spreading of these cells observed in the morphological analysis.

Alkaline Phosphatase↗
PubMed1987

Unique phenotype of opaque cells in the white-opaque transition of Candida albicans.

Select strains of Candida albicans switch reversibly and at extremely high frequency between a white and an opaque colony-forming phenotype, which has been referred to as the white-opaque transition. Cells in the white phase exhibit a cellular phenotype indistinguishable from that of most standard strains of C. albicans, but cells in the opaque phase exhibit an unusually large, elongate cellular shape. In comparing the white and opaque cellular phenotypes, the following findings are demonstrated. (i) The surface of the cell wall of maturing opaque cells when viewed by scanning electron microscopy exhibits a unique pimpled, or punctate, pattern not observed in white cells or standard strains of C. albicans. (ii) The dynamics of actin localization which accompanies opaque-cell growth first follows the pattern of budding cells during early opaque-bud growth and then the pattern of hypha-forming cells during late opaque-bud growth. (iii) A hypha-specific cell surface antigen is also expressed on the surface of opaque budding cells. (iv) An opaque-specific surface antigen is distributed in a punctate pattern.

Actins↗
PubMed1987

Polymyositis complicating staphylococcal septicaemia.

Inflammatory polymyositis can be precipitated by acute febrile illness of viral origin, but similar association with pyogenic bacterial illness is not recognised. We describe two cases in which recovery from staphylococcal septicaemia was complicated by a widespread inflammatory myopathy.

Female↗
PubMed1987

Structure/function analyses of IL-2 binding proteins on human B cell precursor acute lymphoblastic leukemias.

We have studied the expression and function of interleukin-2 (IL-2) receptors on B cell precursor acute lymphoblastic leukemias (ALL). After incubation of B cell precursor ALL in vitro for 24 hr, 11 out of 17 leukemic bone marrow aspirates expressed the Tac/CD25 protein (greater than 10% positive blasts). Expression of Tac/CD25 on the leukemic cells was confirmed by two color flow cytometric analysis using anti-Tac/CD25 and anti-CALLA/CD10 monoclonal antibodies. The molecular mass of the B cell precursor ALL Tac/CD25 protein was 55 kilodaltons (kD), identical to that on activated T cells. Binding of radiolabeled IL-2 in two leukemic bone marrow aspirates demonstrated the presence of high affinity IL-2 receptors. Cross-linking of 125I-labeled IL-2 to TPA activated B cell precursor ALL revealed the 55 kD Tac/CD25 protein and an additional protein of 75 kD. Recombinant IL-2 in concentrations of 10-1,000 U/ml had essentially no proliferative effect in 10 patients tested, whereas low molecular weight B cell growth factor (L-BCGF) induced proliferation in 8 of 10 patients. L-BCGF also induced expression of CD20 in 3 of 7 CD20 negative B cell precursor ALL. IL-2 did not induce CD20, but enhanced its expression in the 3 patients who responded to L-BCGF. We conclude that IL-2 has essentially no proliferative effect on B cell precursor ALL, despite the presence of high affinity IL-2 receptors and the presence of the IL-2 binding cell surface molecules similar to those on activated T cells. IL-2 may, however, induce a phenotypic change (CD20 acquisition) consonant with differentiation in synergy with L-BCGF.

B-Lymphocytes↗
PubMed1987

Nosocomial graft fragmentation and healing response of an ePTFE angioaccess graft.

This investigation was directed toward the tissue reaction and wound healing response of an ePTFE prosthesis implanted in a human subject as an arteriovenous fistulae for over 7 years. Due to the frequent puncture of the prosthesis for hemodialysis access, the pattern of healing is markedly different from that normally observed in ePTFE grafts in humans. The ePTFE graft material of the AV fistula was completely incorporated in fibrous tissue with prominent pseudointima formation (inner capsule), fibrous tissue within the graft and a well-adhered periadventitial layer (outer capsule). In the portion of the graft most frequently punctured, the wall of the graft was composed mainly of fibrous tissue containing dissociated fragments of ePTFE. Biochemical analysis of the fibrous tissue across the wall of the graft revealed that it contained types I, III, and V collagen, with type I greater than III greater than V. The type V collagen was present in largest percentage at the luminal surface and in decreasing percentage in the ePTFE material and outer capsule. This analysis suggests that collagen type deposition in this prosthesis occurs in a manner similar to a normal healing wound, except for the unusual pattern of type V collagen deposition, which may be an adaptive variation of the healing response.

Adult↗
PubMed1986

Cross-linking of a growth hormone releasing factor-binding protein in anterior pituitary cells.

Growth hormone-releasing factor (GRF) stimulates the release of growth hormone from the anterior pituitary and is related to the peptides of the glucagon/secretin family. Although the mechanism of action of this hormone has been studied in considerable detail, little is known concerning the GRF receptor itself. We have attempted to label the GRF receptor by chemically coupling the 125I-GRF analog [His1, Nle27]-hGRF(1-32)-NH2 (GRFa) (where Nle is norleucine) to plated rat anterior pituitary cells with the protein cross-linker disuccinimidyl suberate (DSS) (0.1 mM). Verification of biological activity of the 125I-GRFa was confirmed prior to the cross-linking experiments using the reverse hemolytic plaque assay. Whole cell extracts prepared from the cross-linked cells were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography of the dried gels. Four bands of 72, 50, 30, and 26 kDa were detected in autoradiograms from cells exposed to the labeled analog for 20 min (22 degrees C) followed by exposure to DSS for 2 min. The 72-kDa band was interpreted to be bovine serum albumin, which was used as a carrier in initial studies. The 50- and 30-kDa bands were very faint and probably represent nonspecific binding sites since they were unchanged in the presence of excess unlabeled GRFa. The 26-kDa band was diminished in a concentration-dependent manner by unlabeled rat GRF, GRFa, and to a lesser extent by vasoactive intestinal peptide (VIP). It is unlikely, however, that GRFa was acting at a VIP receptor since the labeled analog did not induce prolactin secretion (VIP is a prolactin secretagogue). GRFa also increased cellular cAMP to levels similar to GRF and greater than VIP. Autoradiographs from gels run under nonreducing conditions revealed the 26-kDa band as the major species, indicating that, if a polymeric form of this binding protein exists, it does not involve disulfide linkages. Thus, the best candidate for the putative GRF receptor is the 26-kDa band. We have further demonstrated that the higher concentrations of DSS used previously (5 mM) result in diffuse autoradiograms with multiple bands, suggesting that caution should be exercised when interpreting cross-linking data under these conditions.

Animals↗