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M Adam

Publications and source records attributed to M Adam.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Comparison of 2 methods for determining antibodies to collagen: the ELISA test and passive hemagglutination].

For the determination of antibodies against collagen in different rheumatic diseases the authors elaborated two serological techniques. It was particularly the passive haemagglutination, which proved to be little sensitive and insufficiently reproducible. Therefore, for the determination of antibodies against collagen the authors introduced the ELISA method as one of the varieties of enzyme immunoanalysis, giving more precise results. Both methods were compared and it has become apparent that the ELISA method is more reliable and more suitable for the determination of antibodies against collagen.

Autoantibodies↗
PubMed1988

Separation of type IX collagen from other cartilage collagens by hydrophobic interaction chromatography.

Collagen type IX was separated from other cartilage collagens (types II and XI) by hydrophobic interaction chromatography on a 25 cm X 8 mm I.D. stainless-steel column packed with Separon HEMA 1000 Bio. The mobile phase was 0.84 M ammonium sulphate with 0.1 M potassium dihydrogenphosphate (pH 6.5). Under these conditions only collagen type IX was eluted from the column; it could be monitored with UV detection (218 nm) or selectively with fluorescence detection (excitation 330 nm, emission filter 389 nm). The method can be used for the isolation and quantitation of collagen type IX. The assay was linear in the range 0-10 micrograms, the correlation coefficient was 0.99, precision 5.5% and accuracy 13%. The detection limit was about 0.6 microgram.

Animals↗
PubMed1988

Incorporation of myristate and palmitate into the sheep reticulocyte transferrin receptor: evidence for identical sites of labeling.

The ability of sheep reticulocytes and plasma membranes isolated from them to incorporate fatty acids into the transferrin receptor has been examined using both [3H]palmitate and [3H]myristate. Both fatty acids, when incorporated into the transferrin receptor, can be released by treating the protein with 1 M hydroxylamine at pH 7.0. After treatment of the 3H-acylated receptor with borohydride, an 3H-labeled alcohol is released, suggesting that the receptor-bound fatty acid is in thioester linkage. With both [3H]myristate and [3H]palmitate, Cleveland maps from immunoprecipitates of the transferrin receptor labeled in intact cells and isolated membranes show that identical peptides are labeled. No evidence was obtained for qualitatively different labeling with the two fatty acids. In intact reticulocytes, incorporation of [3H]palmitate into the transferrin receptor is approximately 3.5 times greater than the incorporation of [3H]myristate from equivalent concentrations of the labeled fatty acids. However, in isolated reticulocyte plasma membranes, there is much less difference between palmitate and myristate incorporation (with ATP) or between their acyl-CoA derivatives. The reason for the discrepancy between cells and membranes is unknown but may be due to the presence in intact cells of more than one enzyme for activating the fatty acids. Acylation of the receptor in isolated plasma membranes is fourfold greater with the CoA derivatives than with the free fatty acids. The fatty acid activating enzyme(s) as well as the acyltransferase(s) appear to be membrane bound in reticulocytes.

Acylation↗
PubMed1988

Anticollagen antibodies in patients with juvenile chronic arthritis.

Using ELISA antibodies, titres to collagen type I, II and III in sera of patients with juvenile chronic arthritis (JCA) were assayed. Results were compared with titres of patients with rheumatoid arthritis (RA). Increased antibodies titres to all three collagen types were found in comparison with healthy individuals of the same age. Average titres in patients with RA were higher than those of the JCA group. When antibodies titres were correlated with erythrocyte sedimentation rate in 1 hour (ESR/1h) statistical significance was found only in RA group for collagen type II.

Adolescent↗
PubMed1988

Regional cerebral glucose metabolism in identical twins.

The present study reports on the degree of similarity in regional cerebral glucose metabolism in seven sets of female identical twins. All scans were done with subjects at rest. Glucose metabolism was measured with positron emission tomography (PET). Significant intraclass correlations were found for the orbital and prefrontal cortex as well as the basal ganglia (caudate/putamen). It is suggested that these correlations reflect the functional aspects of these areas, namely attention and posturing movements.

Adult↗
PubMed1988

Changes in type V collagen in the kidneys of DOCA-NaCl treated rats.

Type V collagen was extracted and quantitated in the kidneys of unilaterally nephrectomized rats exposed to desoxycorticosteron acetate (DOCA-NaCl) treatment. A highly elevated content of collagen type V was found in these kidneys compared with controls. A higher content of collagen type V was present both in the pepsin digest of the total kidney and in the isolated glomerular basement membranes. It was previously reported that one of the factors involved in the growth of the remaining kidney in unilaterally nephrectomized DOCA-NaCl treated rats is the increase of collagen type IV, the effect being more prominent in rats nephrectomized at a younger age. The present study documents that the increase of type V collagen follows the same pattern.

Animals↗
PubMed1987

Altered metabolism of [18F]-6-fluorodopa in the hooded rat following inhibition of catechol-O-methyltransferase with U-0521.

[18F]-6-Fluoro-L-DOPA ([18F]DOPA), a tracer for cerebral dopamine in studies utilizing positron emission tomography (PET), is rapidly metabolized by catechol-O-methyltransferase (COMT) in the periphery following intravenous injection to carbidopa-pretreated humans and rats. Experiments were performed to determine the effect of pretreatment with 3',4'-dihydroxy-2-methyl-propiophenone (U-0521), a competitive inhibitor of COMT, on [18F]DOPA metabolism in the carbidopa-pretreated hooded rat. U-0521 (25 mg/kg, i.p.), administered 10 min prior to the [18F]DOPA, served to increase the persistence of [18F]DOPA in plasma over a 2-hr period by decreasing the rate of formation of the peripheral metabolite 3-O-methyl-6-fluorotyrosine (Me[18F]DOPA). This compound passes readily into brain and was the sole [18F]DOPA metabolite observed in cortex and cerebellum. U-0521 produced a short-lasting decrease in Me[18F]DOPA levels in these two tissues. In striatum, decreases in Me[18F]DOPA were found to last at least 90 min. Associated with the elevated availability of [18F]DOPA in plasma produced by U-0521 were 50% increases in striatal [18F]dopamine ([18F]DA) levels and 40% increases in the levels of [18F]dihydroxyphenylacetic acid ([18F]DOPAC) at times between 30 and 90 min following [18F]DOPA injection. Increased decarboxylation of [18F]DOPA in the striatum of U-0521-treated rats resulted in heightened radiocontrast between striatum and other cerebral tissues.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Vesicle formation during reticulocyte maturation. Association of plasma membrane activities with released vesicles (exosomes).

Vesicles are released during the in vitro culture of sheep reticulocytes which can be harvested by centrifugation at 100,000 X g for 90 min. These vesicles contain a number of activities, characteristic of the reticulocyte plasma membrane, which are known to diminish or disappear upon reticulocyte maturation. The activities include acetylcholinesterase, cytochalasin B binding (glucose transporter) nucleoside binding (i.e. nucleoside transporter), Na+-independent amino acid transport, and the transferrin receptor. Enzymes of cytosolic origin are not detectable or are present at low activity in the vesicles. Cultures of whole blood, mature red cells, or white cells do not yield comparable levels of these activities, supporting the conclusion that the activities arise from the reticulocytes. In addition, the lipid composition of the vesicles shows the high sphingomyelin content characteristic of sheep red cell plasma membranes, but not white cell or platelet membranes, also consistent with the conclusion that the vesicles are of reticulocyte origin. It is suggested that vesicle externalization may be a mechanism for shedding of specific membrane functions which are known to diminish during maturation of reticulocytes to erythrocytes.

Acetylcholinesterase↗
PubMed1987

Calcification of poly(2-hydroxyethyl methacrylate)-collagen composites implanted in rats.

Samples of the polyHEMA-collagen composites with varying collagen content have been implanted into the popliteal region of rats. Three, six and twelve months after the implantation, calcification of the implanted material was determined using a radioactive indicator. At the same time, the implants and surrounding tissue were examined histologically. The degree of calcification of the implants was dependent on the collagen content; it was more pronounced with a higher amount of collagen. The composites with 30% (w/w) or more collagen were biodegraded during the long-term implantation. It is suggested that the composites containing less than 20% (w/w) of fibrillar collagen are used for biomedical applications and that those with a higher collagen content for the in vitro studies.

Animals↗
PubMed1987

The metabolism of [18F]6-fluoro-L-3,4-dihydroxyphenylalanine in the hooded rat.

The metabolism of the positron-emitting compound [18F]6-fluoro-L-3,4-dihydroxyphenylalanine (*F-DOPA) was studied in carbidopa-pretreated male hooded rats. Thirty minutes following carbidopa administration (5 mg/kg i.p.), animals received *F-DOPA (500 micrograms/kg; specific activity, 175-230 Ci/mol) as an intrajugular bolus. Blood samples were taken at various times between 5 and 90 min, and the plasma was analyzed by HPLC with gamma counting of fractions. *F-DOPA disappeared rapidly from plasma in concert with the formation of the 3-O-methylated metabolite, Me-*F-DOPA. Animals were killed from 5 to 120 min after injection, and the brains were rapidly dissected. The disappearance of *F-DOPA from both vermis and striatal samples was rapid. Me-*F-DOPA, the sole metabolite observed in the vermis, was the major labeled material in the striatum at greater than or equal to 20 min after injection. Fluorodopamine was an important metabolite in the striatum, making up 25% of total radioactivity at early intervals. Striatal samples also contained fluoro-3,4-dihydroxyphenylacetic acid, which constituted approximately 10% of the total radioactivity, and traces of two radiolabeled compounds, tentatively identified as fluorohomovanillic acid and fluoro-3-methoxytyramine.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Externalization of membrane-bound activities during sheep reticulocyte maturation is temperature and ATP dependent.

During the maturation of sheep reticulocytes in vitro, there is release of material that can be pelleted from the cell-free incubation medium by centrifugation at 100,000 X g. This pellet contains activities that are derived from both the plasma membrane and lysosomes. No evidence was obtained for the presence of mitochondrial activities or cytosolic enzyme activities. The release of these activities is ATP and temperature dependent, since reduction of either results in a greater retention of the activities by the cells and a lesser amount in the 100,000 X g pellet. The pelleted material is vesicular in nature, and the production and (or) release of the material are reduced upon ATP depletion or lowering of the temperature. It is concluded that the externalization of specific membrane components is a normal metabolic process that occurs during reticulocyte maturation and represents a means by which reticulocytes shed specific types of membrane-associated functions that are known to decrease during reticulocytes maturation.

Adenosine Triphosphate↗
PubMed1987

Effect of tolfenamic acid on the metabolism of the main connective tissue components in rats.

Tolfenamic acid (Clotam) has been used in the therapy of rheumatic diseases for some years. Regarding its chemical structure it belongs to the group of fenamates. The effect of tolfenamic acid on the synthesis of collagen and proteoglycans in granulation tissue, skin or cartilage of rat weanlings was tested and compared with the action of mefenamic acid. According to the results obtained, tolfenamic acid is a potent inhibitor of collagen as well as proteoglycan syntheses. The concentrations of the constituents of proteoglycans, i.e. protein core, link protein as well as glycosaminoglycans were decreased in the tissue after treatment with tolfenamic acid. In comparison with mefenamic acid, if the same doses were used (50 mg and 100 mg/kg of body weight/day in in vivo experiments and 10 mg/g wet tissue in in vitro experiments), tolfenamic acid exhibits more distinct inhibitory effect. A general inhibitory effect of tolfenamic acid on proteosynthesis is suggested.

Animals↗
PubMed1986

Hepatitis-B as a prognostic discriminant in patients with primary liver cancer.

The prognostic significance of positive serologic determination of hepatitis-B was investigated in 137 patients with primary liver cancer seen over a 6-year period in Pretoria. The median survival time of the 137 patients was 93 days. Patients who were anicteric had a longer survival. Patients who showed positive results for hepatitis-B surface antigen (HBsAg) had a median survival time of 135 days, (39 patients) whereas patients who were HBsAg-negative had a median survival time of 96 days (66 patients). In 57 patients, one or more of the serologic determinations, HBsAg, HBeAg, anti-HBs, anti-HBe, and/or anti-HBc, were positive. Their median survival was 118 days. When HBsAg positivity (or negativity) is corrected for bilirubin, the median survival time remains a function of the bilirubin.

Adult↗