Biomedical subjects
Publications and source records attributed to C C Clark.
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Nurses in upper- and middle-management positions often struggle with issues related to assertiveness. The author lists some questions that nursing administrators and managers have raised at assertiveness workshops and offers some answers.
Six laboratories collaboratively studied a method for the quantitative gas-liquid chromatographic (GLC) determination of phencyclidine.HCl in powders. The phencyclidine.HCl and other water-soluble compounds are dissolved in dilute HCl. A portion of the aqueous solution is made weakly basic with K2HPO4, and the organic-soluble compounds are extracted in CHCl3 for the GLC determination of the phencyclidine.HCl. Eicosane (n-C20) is incorporated in the extracting CHCl3 as an internal standard. The samples collaboratively studied included samples of known phencyclidine.HCl concentration and one sample of unknown purity. Recoveries ranged from 92.1 to 104% and per cent standard deviations from 1.05 to 3.39. The method was adopted as official first action.
Type I procollagen secreted by matrix-free chick embryo tendon cells was labeled with L-[3,3'-3H] cystine and purified by DEAE-cellulose chromatography. After bacterial collagenase digestion, the NH2- and COOH-terminal propeptides were partially characterized by ion exchange chromatography and gel filtration. Similar experiments were then conducted after labeling with either D-[6-3H] glucosamine, D-[2-3H] mannose, or D-[U-14C] glucose. On the basis of these studies and subsequent carbohydrate analysis, it was concluded that the COOH-terminal peptide contained greater than 90% of the radioactive carbohydrate which consisted predominantly of glucosamine and mannose with traces of galactosamine and galactose. Only radioactive glucosamine could be detected in the NH2-terminal propeptide. Under conditions which inhibit hydroxylation of lysine and glycosylation of hydroxylysine, unhydroxylated procollagen (protocollagen) could still be labeled with [3H] glucosamine and [3H] mannose. This suggested that glycosylation of the propeptides is at least initiated at the level of the rough endoplasmic reticulum.
Eight laboratories collaboratively studied a method for the quantitative gas-liquid chromatographic (GLC) determination of cocaine.HCl in solid forms. The cocaine.HCl and other water solubles are dissolved in dilute HCl. The aqueous solution is made weakly basic with K2HPO4, and the organic solubles are extracted into CHCl3 for the GLC determination of cocaine. Tetracosane (n-C24) is incorporated in the extracting CHCl3 as an internal standard. Five samples of known cocaine.HCl concentration and one sample of commercial ground tablets were collaboratively studied. The cocaine.HCl content ranged from 6 to 100%. Recoveries ranged from 98.7 to 103%; coefficients of variation ranged from 0.89 to 3.16. The method was adopted as official first action.
Human teeth were used to obtain cementum. Collagen could not be significantly solubilized from the cementum by salt and acetic acid extraction or by pepsin digestion. CNBr digestion (86%) of cementum and subsequent carboxymethyl cellulose chromatography suggests that human cementum consists of type I collagen only as identified by amino acid and hexose analyses.
It would seem on the surface that psychotherapeutic approaches as different as psychoanalysis and behavioral therapy have little in common. In fact, they seem to be similar in terms of expectation of help, nonconfirming experiences, informational learning, changes in self-concept, reinforcement/influence, paradox, and problem solving. Therapists who work with clients who present life-threatening symptoms, self-reinforcing cycles, and/or therapeutic engagement difficulties may do well to consider ways to combine therapeutic approaches in order to deal with these sticky therapeutic problems.
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Basement membrane procollagen biosynthesis was studied in organ cultures of embryonic rat parietal yolk sac endoderm by following [14C]proline incorporation into nondialyzable proteins. After reduction with 2-mercaptoethanol the 14C-proteins synthesized were characterized by agarose gel filtration and disc electrophoresis in the presence of sodium dodecyl sulfate. The labeled procollagen was identified by its content of hydroxy[14C]proline, its sensitivity to digestion with bacterial collagenase, and its resistance to digestion with pepsin. In cultures which were continuously labeled for periods from 6 hours to 4 days, the pro-alpha chains consistently eluted as a single peak with an apparent molecular weight of 160,000. After pepsin digestion the resultant alpha chains had an apparent molecular weight between 125,000 and 140,000. This suggests that basement membrane procollagen either contains non-triple helical pepsin-resistant regions or a triple helical region which is larger than the corresponding region of interstitial procollagen. Two experiments were performed to determine whether the chains of newly synthesized basement membrane procollagen were cleaved to a smaller molecular species. In the first, the hydroxylation and secretion of procollagen were blocked with alpha, alpha'-dipyridyl, and the resulting intracellular chains of basement membrane protocollagen were found to co-elute with fully hydroxylated and secreted pro-alpha chains. In the second, cultures were labeled for 1 day and chased for 3 days with unlabeled medium. Autoradiography had shown that most of the label was chased into new basement membrane. Agarose chromotography showed that after 3-day chase the pro-alpha chains still eluted with an apparent molecular weight of 160,000. Thus, the data indicated that basement membrane procollagen was deposited in new basement membrane without undergoing a time-dependent extracellular conversion.
Cells obtained from chick embryo tendons incorporate isotopically labeled glucosamine and mannose into the pro-alpha1 and pro-alpha2 chains of procollagen as judged by sodium dodecyl sulfate-gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The label was further localized to the propeptides of pro-alpha1 and pro-alpha2 by its chromatographic behavior after digestion with bacterial collagenase or alpha-chymotrypsin. Carbohydrate analysis of isolated pro-alpha chains showed the presence of labeled galactosamine in addition to mannose and glucosamine. Resistance to mild alkaline hydrolysis suggested that greater than 90% of the oligosaccharide units are not linked to the propeptide backbone by either serine or threonine.
Reserpine-rescinnamine group alkaloids are extracted from Rauwolfia serpentina preparations into a dimethylsulfoxide (DMSO)-methanol mixture and diluted with 0.5N H2SO4. The chloroform extract of this solution is passed through a 0.1N NaOH-Celite column and then through a silica gel column. The weakly basic alkaloids trapped on the latter column are eluted with a methanol mixture; a portion of the eluate is treated with nitrous acid and the reserpine-rescinnamine content is determined by measuring the intensity of fluorescence of the oxidation product. The following means and standard deviations (11 collaborators) were obtained for the determination of reserpine-rescinnamine group alkaloids in 4 samples of Rauwolfia serpentina (NF reference powder, 100 mg and 50 mg commercial tablets, and a 45 mg synthetic tablet formulation) : 0.174% +/- 0.0112, 0.131% +/- 0.0047, 0.160% +/- 0.0100, and 0.153% +/- 0.0083, respectively.
The alpha2 chain of guinea pig skin collagen contains two additional methionyl residues in comparison with the alpha2 chain of other vertebrate species. The order of the three CNBr peptides unique to the alpha2 chain was established on the basis of the homology of their primary structures to sequences of previously ordered regions in the alpha1 and alpha2 chains of other colagens. The two larger peptides, 4A + 4B, were found to correspond to the region homologous to alpha2-CB4 of other species, while the smaller peptide, 3A, was homologous to the NH2-terminal portion of alpha2-CB3. Thus, the order of the peptides in the alpha2 chain of this collagen is 1-O-4A-4B-2-3A-3B-5. Periodate oxidation and alkaline or acid hydrolysis of the CNBr fragments showed that all of the hydroxlysine-linked carbohydrate in the alpha2 chain was present in alpha2-CB4B. Carbohydrate analyses were most consistent with the existence of single monosaccharide and disaccharide units in this region.
Basement membrane biosynthesis in vitro was studied in a rapidly growing embryonic tissue, the rat parietal yolk sac. This tissue consists of a thick, nonvascular basement membrane (Reichert's membrane) separating two cellular layers (parietal endoderm and trophoblast). Morphologically, Reichert's membrane appeared similar to other basement membranes. Previous analysis of the amino acid and carbohydrate composition of acellular Reichert's membrane showed it to be typical of basement membranes isolated from other tissues and species. Analysis of [14-C]proline incorporation and hydroxy [14-C]proline synthesis during the third quarter ogestation in vitro showed that basement membrane collagen synthesis in the parietal yolk sac was maximal around the 14th day of gestation. At this time, basement membrane collagen represented nearly 10% of the newly synthesized protein. The collagen synthesized in this system was characteristic of basement membrane collagen in that about 11% of the total hydroxy [14-C]proline was present as the 3-isomer. In addition, after incubation in the presence of [14-C]lysine, 83 to 94% of the hydroxy[14-C]lysine was glycosylated, with the predominant form being glucosylgalactosylhydroxy[14-C]lysine. When the parietal endoderm and trophoblast were incubated separately with [14-C]proline, it was determined that the former was solely responsible for the synthesis of basement membrane collagen since essentially all of the 4-hydroxy[14-C]proline was associated with this cell type. Autoradiographic experiments with [3-H]glucosamine also served to localize the synthesis of noncollagen basement membrane glycoprotein components to the parietal endoderm. As with the results reported for basement membrane collagen secretion in embryonic chick lens cells, there appeared to be approximately a 60-min delay between the incorporation of [14-C]proline into protein and the secretion of collagen as measured by the appearance of 4-hydroxy[14-C]proline in the culture medium. Experiments utilizing [3H]glucosamine to monitor glycoprotein synthesis did not show a delay between the incorporation of [3H]glucosamine and the secretion of nondialyzable 3-H into the medium. The results obtained using the parietal yolk sac system to study basement membrane biosynthesis were compared to those previously obtained using the kidney glomerular and embryonic chick lens systems. It was concluded that the parietal yolk sac system is superior for a number of reasons: (a) the extracellular matrix appeared to contain only basement membrane components; there was no contamination by acid mucopolysaccharides or other types of collagen; (b) only a single cell type appeared to be responsible for the synthesis of basement membrane components; and (c) a relatively large percentage of the newly synthesized protein was basement membrane collagen.