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Biomedical subjects

C C Clark

Publications and source records attributed to C C Clark.

At least 19 recordsLinked to original sources
PubMed1992

Helmet use, patterns of injury, medical outcome, and costs among motorcycle drivers in Maryland.

A comprehensive study was conducted of all motorcycle traffic crashes occurring in Maryland during a one-year period. All available medical and cost data were linked with police crash reports. During the study period, 1,900 motorcycle drivers were involved in crashes. The data indicated that (i) helmet usage was 35% overall, 30% among fatally injured drivers, and only 16% among drivers with a history of drug/alcohol conviction, (ii) unhelmeted drivers seen at an emergency department were almost twice as likely to have sustained head injury (40%) as were helmeted drivers (21%) (the corresponding percentages for hospitalized drivers were 55% and 38%), and (iii) acute care cost for unhelmeted drivers was three times ($30,365) that of helmeted drivers.

Accidents, Traffic↗
PubMed1992

In vitro bone-cell response to a capacitively coupled electrical field. The role of field strength, pulse pattern, and duty cycle.

Newborn rat calvarial bone cells were grown to confluence and subjected to a matrix of sine wave 60-kHz capacitively coupled electrical signals of various field strengths, pulse-burst patterns, and duty cycles. Both [3H] thymidine incorporation into DNA and alkaline phosphatase activity were evaluated in field strengths ranging from 0.0001 to 20 mV/cm, with pulse-burst patterns ranging from continuous to 5 milliseconds ON/495 milliseconds OFF, with daily duty cycles ranging from 0.25% to 25%. A significant increase in proliferation occurred in field strengths of 0.1, 1, and 20 mV/cm when the signal was applied continuously for six hours. Significant proliferation also occurred when the 20-mV/cm field was pulsed for six hours at 5 milliseconds ON/495 milliseconds OFF and at 5 milliseconds ON/245 milliseconds OFF. No change in alkaline phosphatase activity occurred in the 20-mV/cm field with any signal. At 1 mV/cm, there was a significant decrease in alkaline phosphatase activity in the continuous signal and in the 5 milliseconds ON/62 milliseconds OFF signal; in the lower fields evaluated, there was an actual decrease in alkaline phosphatase activity with some of the signals. The field strength plays a dominant role in determining the bone-cell's proliferative response, and to a lesser extent the alkaline phosphatase activity response, to a capacitively coupled electric field. The pulse configuration and the duty cycle are also important, but only if the proper field strength is being applied to the cell.

Alkaline Phosphatase↗
PubMed1991

Post-translational alterations in newly synthesized cartilage proteoglycans induced by the glutamine analogue 6-diazo-5-oxo-L-norleucine. Time course of inhibition and recovery.

Incorporation of [35S]sulphate by cultures of matrix-free cells from chick embryo sterna in the presence of the glutamine analogue 6-diazo-5-oxo-L-norleucine (0.58 mM) was inhibited in a time-dependent manner to less than 15% of that in control cultures after 2 h. Characterization of the major cartilage proteoglycan synthesized under these conditions showed that it contained few, if any, normal-sized chondroitin sulphate chains and only about half of the normal complement of substituted serine residues. Subsequent addition of D-glucosamine hydrochloride (final concn. 2 mM) resulted in a time-dependent recovery of [35S]sulphate incorporation to 90% of control cultures after 2 h, but restored the chondroitin sulphate chains to normal size within 15 min. On the basis of these results, it is concluded that a 2 h preincubation is necessary to deplete the chondrocytes of the endogenous supply of UDP-N-acetyl-D-glucosamine required for optimal glycoconjugate synthesis, and that this situation results in the synthesis of a chondroitin sulphate proteoglycan with significantly altered properties, owing to the paucity of glycosaminoglycan chains; however, this condition is completely reversible if the D-glucosamine pool is repleted.

Aggrecans↗
PubMed1991

The effect of oxygen tension on proteoglycan synthesis and aggregation in mammalian growth plate chondrocytes.

Growth plate chondrocytes isolated from the proliferative and hypertrophic zones of bovine costochondral junctions were grown in vitro in the presence of various oxygen tensions ranging from 3 to 60%. Using [35S] sulfate as an index of glycosaminoglycan synthesis, incorporation was found to be maximal at 21% O2. In contrast, proteoglycan aggregation under the same conditions was found to be maximal at 3% O2. There were no consistent differences in response between cells from the different morphologic zones even though they are exposed to different oxygen tensions in situ. These results show that proteoglycan synthesis and aggregation in growth plate chondrocytes in vitro are differentially affected by the ambient oxygen environment.

Animals↗
PubMed1991

Proliferation and macromolecular synthesis by rat calvarial bone cells grown in various oxygen tensions.

Perinatal rat calvarial bone cells were isolated by sequential collagenase digestion and grown in oxygen tensions ranging from 1 to 60% O2. Cell proliferation as determined by automated cell counting and DNA content was greatest in the lower oxygen tensions (less than or equal to 9% O2), whereas alkaline phosphatase activity and [35S]sulfate and [14C]proline incorporation were greatest in the higher oxygen tensions (greater than or equal to 13% O2). It is concluded that lower oxygen concentrations favor bone cell proliferation, whereas higher oxygen concentrations favor macromolecular synthesis. These findings, when related to the known pO2 of the fracture callus, suggest the following sequence of events: first, at the time of fracture an ingrowth of osteoprogenitor cells, capillary buds, and primitive mesenchymal cells occurs in the fracture site, a region of low pO2; second, a great increase in cellular proliferation accompanied by an initiation of macromolecular synthesis follows; finally, as the pO2 levels begin to increase, cellular proliferation decelerates, accompanied by an increase in macromolecular synthesis.

Alkaline Phosphatase↗
PubMed1991

Proteoglycan synthesis and content in articular cartilage and cartilage repair tissue in horses.

Hexosamine concentration, DNA concentration, and [35S]sulfate incorporation for articular cartilage obtained from various sites in the metacarpophalangeal and carpal joints of horses were measured. The same measurements were made on the repair tissue filling full-thickness articular defects in the intermediate carpal bone and on cartilage surrounding partial-thickness defects 6 weeks after the defects were created arthroscopically. Cellularity (measured as DNA concentration), proteoglycan content (measured as hexosamine concentration), and proteoglycan synthesis (measured as [35S]sulfate incorporation) varied according to the site sampled. Cartilage from the transverse ridge of the head of the third metacarpal bone and the radial facet of the third carpal bone had the lowest hexosamine concentration, whereas rate of proteoglycan synthesis was lowest in cartilage from the transverse ridge of the head of the third metacarpal bone and the distal articular surface of the radial carpal bone. Repair tissue filling a full-thickness cartilage defect at 6 weeks was highly cellular. It was low in proteoglycan content, but was actively synthesizing these macromolecules. In contrast, the cartilage surrounding a partial-thickness defect was unchanged 6 weeks after the original defect was made.

Animals↗
PubMed1991

Spirituality: integral to quality care.

Caring is the medium through which nursing knowledge, skill, and touch are operationalized. Caring is a profound act of hope (White T. 1986. Unpublished data) that contributes to the spiritual well-being of others. In order to assure quality care, the impact of identifying and meeting patient spiritual needs must be taken into account.

Empathy↗
PubMed1979

Assertiveness issues for nursing administrators and managers.

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.

Administrative Personnel↗
PubMed1979

Gas-liquid chromatographic quantitation of phencyclidine.HCl in powders: collaborative study.

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.

Chromatography, Gas↗
PubMed1978

Localization and partial composition of the oligosaccharide units on the propeptide extensions of type I procollagen.

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.

Animals↗
PubMed1978

Gas-liquid chromatographic quantitation of cocaine.HCl in pouders and tablets: collaborative study.

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.

Chromatography, Gas↗
PubMed1977

A preliminary characterization of human cementum collagen.

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.

Amino Acids↗
PubMed1977

Combining therapeutic approaches.

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.

Behavior Therapy↗