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Biomedical subjects

M Chapman

Publications and source records attributed to M Chapman.

At least 91 records · Page 5Linked to original sources
PubMed1991

Multicenter trial of Collagraft as bone graft substitute.

Collagraft (Zimmer and Collagen Corporation) consists of a mixture of porous beads composed of 60% hydroxyapatite and 40% tricalcium phosphate ceramic and fibrillar collagen. When mixed with autogenous bone marrow, it serves as an effective bone graft substitute. Since September 1986, this material has been used in a multiclinic prospective trial, randomized against cancellous iliac crest autografts in the treatment of long bone fractures. To date, 267 patients have entered this study with 128 patients receiving cancellous autograft and 139 patients receiving Collagraft. At 6- and 12-month follow-ups, Collagraft appears to function as well as autogenous graft when used in the treatment of acute long bone fractures.

Adolescent↗
PubMed1989

An ecological approach to the prevention of injuries due to drinking and driving.

Among the many alcohol-related public health concerns, motor vehicle crashes account for nearly one-third of all deaths attributable to alcohol. Adolescents and young adults, particularly males, are important target populations for intervention efforts. Taking an ecological perspective of individuals within their social and physical environments, a diagnostic framework is employed in reviewing the literature on factors associated with drinking and driving injuries and on interventions to prevent injuries due to drinking and driving. Intervention planning is conceptualized according to a multilevel intervention framework, which consists of four phases: (1) health goals selection, (2) intervention planning, (3) intervention, and (4) evaluation. Possible intervention objectives, targets of the intervention actions, intervention approaches, and evaluation criteria are identified and discussed for three societal levels and four practice settings.

Accidents, Traffic↗
PubMed1989

Effect of hetastarch, mannitol, and phenylephrine on spinal cord blood flow following experimental spinal injury.

Anesthetized lambs were subjected to epidural cord compression at T13 by means of an epidural balloon distended to 200 mmHg for 80 minutes. Determinations of spinal cord blood flow (SCBF) were made by labelled microspheres prior to and during compression, and then 1/2, 1 1/2, and 2 1/2 hours after compression. Twelve control animals received saline (80 ml/h). Nine animals received hetastarch (a 20 ml/kg bolus followed by an 80 ml/h infusion) and 8 animals received mannitol (a 1 g/kg bolus followed by 1 g/kg/hr). An additional 10 animals received phenylephrine to raise mean arterial pressure by 20 to 40%. Somatosensory evoked potentials (SEPs) were recorded following each determination of SCBF. Animals were killed following determination of the 2 1/2 hour postcompressive flow. The animals treated with either hetastarch or phenylephrine had a postcompressive mean arterial pressure that was significantly greater than that of the controls (P less than 0.01). During treatment, cardiac output in the hetastarch and mannitol animals was significantly greater and hematocrit significantly less than in the controls (P less than 0.05). In spite of these changes, postcompressive SCBF was significantly increased only in those animals treated with phenylephrine (P less than 0.05). Statistical analysis of the relationship between mean arterial pressure and postcompressive SCBF revealed that autoregulation is indeed lost with this experimental model of spinal cord injury. Histological examination of the injured site failed to demonstrate any difference in the area of hemorrhagic necrosis among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Children's agency beliefs, cognitive performance, and conceptions of effort and ability: individual and developmental differences.

In order to understand how children's beliefs and cognitive performance vary according to development in their conceptions of effort and ability, 120 fourth and sixth graders were given the following assessments: (a) a measure of agency beliefs, defined as the extent to which persons believe they have access to certain classes of potential means, including effort, ability, powerful others, and luck; (b) a battery of intelligence test scales, including figural patterns, letter series, arithmetic, and spelling; (c) an interview designed to assess developmental levels in conceptions of effort and ability. Correlations between intelligence scores and agency beliefs for effort decreased with increasing levels of reasoning about effort and ability, but correlations between intelligence scores and agency beliefs for ability increased with increasing levels of reasoning. No such trends were found in correlations between performance and agency beliefs for luck or for unknown causes. The results are discussed in terms of the interaction between individual differences and developmental change.

Aptitude↗
PubMed1988

Comparison of rapid in situ, regular in situ, and ex vivo flushing on hepatic function.

The efficacy of three flushing techniques on subsequent liver function was assessed using the in vivo isolated liver perfusion model (ILPM). Livers from brain-dead mongrel dogs were flushed with cold Euro-Collins as follows: Group I, rapid in situ flushing (10 min); Group II, regular in situ flushing (45 min); Group III, ex vivo flushing (10 min). All livers were then heterotopically transplanted into recipients, using the ILPM, by anastomosis of the portal vein, vena cava, and hepatic artery to the recipient's portal vein, iliac vein, and iliac artery. Reperfusion followed for 30 min. Laboratory samples collected at 0, 5, 15, and 30 min showed that hepatic function was not altered by ex vivo flushing and was only slightly altered by rapid in situ flushing. Regular in situ flushing proved to be damaging to livers. Histological analysis confirmed these findings. Therefore, either rapid in situ or ex vivo flushing can be safely used by the transplant specialist.

Adenosine Triphosphate↗
PubMed1987

Population movement studied at microscale: experience and extrapolation.

The context for this paper is the nature of generalization deriving from the study of particular cases of human behavior. With specific reference to field research on population movement conducted among individuals, households, small groups, and village communities in 3rd world societies, it challenges the convention that both generalization and extrapolation are based inevitably and exclusively on the number of events subject to examination. An evaluation is made of the methodological aspects of 4 different studies of population mobility at microscale, undertaken between 1965 and 1977 in the Solomon Islands and northwest Thailand. On this basis, integrated field designs that incorporate a range of intersecting instruments are favored for their technical flexibility and logical strength. With case studies of 3rd world villages, market centers, and urban neighborhoods, generalization and extrapolation is based on depth of understanding and power of theoretical connections.

Asia↗
PubMed1987

Detection of trophoblast-like cells in maternal blood using specific monoclonal antibodies.

Mouse monoclonal antibodies reacting against membrane antigens expressed on syncytiotrophoblast (McAb H315), villous cytotrophoblast (McAb 18B/A5) and placental-type alkaline phosphatase-producing cells (McAb H317) were used in conjunction with flow cytometry to detect placental cells in the maternal circulation. H315 and H317-positive cells were found in uterine veins and peripheral blood of pregnant women, while cells reacting with McAb 18B/A5 were either absent or present in very low numbers.

Antibodies, Monoclonal↗
PubMed1987

The role of routine intravenous urography in patients with primary hyperparathyroidism.

The plain abdominal radiographs and intravenous urograms of 72 patients with primary hyperparathyroidism were reviewed. Renal tract calcification was detected on plain abdominal radiographs in 27 patients (38%), and intravenous urography revealed no calculi not detected on the plain radiographs. Intravenous urography did, however, show abnormalities not detected on plain abdominal radiographs in 22 patients (37%), but these findings influenced clinical management in only five patients (7%). In these five patients there were indications other than primary hyperparathyroidism for performing an intravenous urogram. Intravenous urography incurs a small risk and should not be performed as a routine investigation in primary hyperparathyroidism.

Adult↗
PubMed1987

Ontogeny of human suppressor inducer T cell subset.

A T cell subset (T4+,2H4+) has recently been identified, which acts as an inducer of T8+ suppressor cells; however 2H4 molecules have not been detected in thymuses from normal individuals or on the surface of immature thymocyte clones. In the present study, T4+,2H4+ and T8+,2H4+ cells have been found in maternal and new-born blood samples. However, only a small percentage of 2H4+ cells were detected in human fetal thymus, bone marrow, liver and spleen, thus suggesting that T cells acquire these molecules only in circulation and at a late stage of maturation.

Antibodies, Monoclonal↗
PubMed1986

DNA-mediated transfer of cAMP resistance in CHO cells.

Chinese hamster ovary (CHO) strain 10215 carries a dominant mutation which confers resistant to cAMP by virtue of an altered catalytic subunit of the cAMP-dependent protein kinase (Evain et al., 1979). This mutation was transferred to wild-type CHO cells by DNA-mediated gene transfer. Based on the absence of cAMP growth inhibition, seven transformant colonies were isolated. One of these, 11586, was studied in detail. This transformant showed the same phenotype as the mutant, including resistance to the morphological changes and growth inhibitory effects of 1 mM 8-Br-cAMP, reduced total cAMP dependent protein kinase activity and lowered sensitivity of the kinase to cAMP activation. When the cAMP-dependent protein kinase was fractionated on a DEAE-cellulose column, the transformant was lacking in type II cAMP dependent protein activity, to the same degree as the mutant. The transformant and mutant, but not wild-type cells, also failed to phosphorylate a 52,000-dalton protein in a cAMP-dependent manner. These characteristics support the conclusion that the gene for the mutant cAMP-dependent protein kinase has been transferred. The ability to transfer this gene by DNA-mediated transfer suggests that this methodology may be useful for the molecular isolation of the gene encoding the catalytic subunit of cAMP-dependent protein kinase.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1986

Radiologic pitfalls in endoscopic retrograde pancreatography.

Endoscopic pancreatography (ERCP) is currently the least invasive technique for obtaining detailed images of the pancreatic ductal system. Although expert ERCP is now an acceptably safe procedure, interpretation of endoscopic pancreatograms may be difficult, and misdiagnosis is still a risk to the patient. We have been able to divide misinterpretations into three broad categories: technical error, anatomic variation, and unusual images due to disease. Examples of each of these classifications are presented and discussed in hopes of decreasing the incidence of misdiagnosis.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1985

Characterization of a cyclic AMP-resistant Chinese hamster ovary cell mutant containing both wild-type and mutant species of type I regulatory subunit of cyclic AMP-dependent protein kinase.

We have characterized a cyclic AMP-resistant Chinese hamster ovary (CHO) cell mutant in which one of two major species of type I regulatory subunit (RI) of cyclic AMP-dependent protein kinase is altered. Wild-type CHO cell extracts contain two cyclic AMP-dependent protein kinase activities. As shown by DEAE-cellulose chromatography, there is a peak of type I protein kinase activity in mutant extracts, but the type II protein kinase activity is considerably reduced even though free type II regulatory subunit (RII) is present. The type I kinase from the mutant has an altered RI (RI*) whose KD for the binding of 8-N3[32P] cAMP (KD = 1.3 X 10(-5) M) is increased by more than 200-fold compared to RI from the wild-type enzyme (KD = 5.5 X 10(-8) M). No differences were found between the catalytic subunits from the wild-type and mutant type I kinases. A large portion of RI in mutant and wild-type extracts is present in the free form. The RI* derived from mutant type I protein kinase shows altered labeling by 8-N3[32P]cAMP (KD = 1.3 X 10(-5) M) whereas the free RI from the mutant is labeled normally by the photoaffinity label (KD = 7.2 X 10(-8) M), suggesting that the RI* which binds to the catalytic subunit is functionally different from the free form of RI. The decreased amount of type II kinase activity in the mutant appears to be due to competition of RI* with RII for binding to the catalytic subunit. Translation of mRNA from wild-type CHO cells results in the synthesis of two different charge forms of RI, providing biochemical confirmation of two different species of RI in CHO cells. Additional biochemical evidence based on isoelectric focusing behavior of 8-N3[32P]cAMP-labeled RI species and [35S]methionine-labeled RI from mutant and wild-type extracts confirms the charge heterogeneity of RI species in CHO cells. These genetic and biochemical data taken together are consistent with the conclusion that there are at least two different species of RI present in CHO cells and that one of these species is altered in the mutant analyzed in this work.

Affinity Labels↗