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Biomedical subjects

C J Boyd

Publications and source records attributed to C J Boyd.

At least 19 recordsLinked to original sources
PubMed2001

Variation in delivery of palliative radiotherapy to persons dying of cancer in nova scotia, 1994 to 1998.

PURPOSE: To examine sociodemographic and clinical variables associated with provision of palliative radiotherapy (RT) to persons dying of cancer. METHODS: The Nova Scotia Cancer Registry was used to identify 9,978 adults who were dying of cancer between 1994 and 1998 in the Canadian province of Nova Scotia. RT records from between April 1992 and December 1998 were obtained from the provincial treatment database. Multivariate analysis identified factors associated with two sequential decisions determining provision of palliative RT in the last 9 months of life: likelihood of receiving an RT consultation with a radiation oncologist and, given a consultation, likelihood of being treated with palliative RT. RESULTS: The likelihood of having a consultation decreased with age (20 to 59 years v. 80+ years: odds ratio [OR], 4.43 [95% confidence interval, 3.80 to 5.15]), increased with community median household income (> $50,000 v. < $20,000: OR, 1.31 [1.02 to 1.70]), was higher for residents closer to the cancer center (< 25 km v 200+ km: OR, 2.47 [2.16 to 2.83]), increased between 1994 and 1998 (OR, 1.34 [1.16 to 1.56]), varied by cause of death (relative to thoracic cancers, head and neck: OR, 1.75 [1.31 to 2.33]; gynecologic: OR, 0.35 [0.27 to 0.44]), and was greater for those who had prior RT (OR, 2.20 [1.89 to 2.56]). Similar associations were observed when outcome was the provision of palliative RT given a consult, with one notable exception: prior RT was associated with a lower likelihood of receiving palliative RT (OR, 0.48 [0.40 to 0.58]). CONCLUSION: Variations observed in delivery of palliative RT should prompt further investigation into equity of access to clinically appropriate, palliative radiation consultation and treatment.

Adult↗
PubMed2001

Dealing with daily hassles: smoking and African-American adolescent girls.

PURPOSE: To examine cigarette use and its relationship to daily life hassles in an urban sample of African-American adolescent girls. METHODS: A sample of 105 African-American adolescent girls (mean age of 15.45 years) derived from a larger cross-sectional research project titled "Female Adolescent Substance Experience Study" funded by the National Institute of Drug Abuse comprised the sample. The sample was divided into adolescents who had ever smoked in their lifetime and adolescents who had never smoked before. Student's t-tests were conducted to determine whether there were differences between these groups on demographic characteristics and the number of daily life hassles. Pearson product moment correlations were also conducted to examine the association between age of smoking initiation and number of hassles. RESULTS: Less than 50% of the teenagers had ever smoked cigarettes in their lifetime, and of those who had ever smoked, the average age of initiation was 12.55 years (SD = 2.63). Furthermore, girls who had ever smoked, in contrast to girls who had never smoked, had a significantly greater number of daily life hassles, in general, and within the school/academic and family/economic domains in particular. Age of smoking initiation was negatively related to the number of hassles, indicating that girls who started to smoke at a younger age reported more hassles. CONCLUSIONS: These findings are discussed in terms of developing an understanding of gender and ethnic-specific correlates of smoking that can be used to better delineate the developmental smoking trajectory of African-American girls.

Adolescent↗
PubMed2000

Associations between community income and cancer incidence in Canada and the United States.

BACKGROUND: Associations between socioeconomic status (SES) and the incidence of cancer have been reported previously in the U.S. Canada has more comprehensive health care and social programs than the U.S. The purpose of this study was to compare the strength of associations between SES and cancer incidence in Canada and the U.S. METHODS: The regions studied were the Canadian province of Ontario and the areas of the U.S. covered by the Surveillance, Epidemiology, and End Results (SEER) program. The populations at risk were defined using the 1991 Canadian Census and the 1990 U.S. Census. The populations of Ontario and of the SEER areas of the U.S. were each divided into deciles on the basis of median household income. Population-based cancer registries were used to identify incident cases. Age-standardized incidence rates for all major groups of malignant diseases were calculated for each SES decile in Ontario and in the U.S. Income-associated incidence gradients observed in Ontario and the U.S. were compared. RESULTS: The incidence of most types of cancer was similar in Ontario and the U.S. In both countries, there were moderately strong, inverse associations between income level and the incidence of carcinomas of the cervix, the head and neck region, the lung, and the gastrointestinal tract. In both Ontario and the U.S., several of these diseases were twice as common in the bottom income decile than they were in the top decile. In contrast, carcinoma of the female breast and carcinoma of the prostate were more common among higher income communities in both countries, but the observed associations were weaker in Ontario. CONCLUSIONS: Despite Canada's universal health insurance and more comprehensive social security system, the association between lower socioeconomic status and the incidence of many common cancers is just as strong in Ontario as it is in the U.S. The mechanisms responsible for these associations require further investigation.

Age Factors↗
PubMed2000

Variation in suicidality among substance-abusing women: the role of childhood adversity.

The relationship of early adversity to suicidality in later life has been noted in diverse populations. Here we report such a relationship for a sample of African American women who smoke crack cocaine. This article is a secondary analysis of data from women (mean age = 31 years; range, 19-48) who were recruited from treatment settings (n = 152) or informal community contacts (n = 56). The present analyses focused on measures related to investment in self-preservation and development, particularly suicidal ideation and attempts. Multiple regression analyses were used to model the effect of early stress (sexual abuse, parental loss, and parental impairment) on the primary outcome measures (suicidality total, age at first consensual sexual relations, and years of education). Suicidality was associated with childhood adversity (sexual abuse, loss of mother). Of those who had experienced early sexual abuse, 42% had attempted suicide, compared to 19% of those who had not been sexually abused.

Adult↗
PubMed1997

Effects of active chronic cocaine use on cardiac sympathetic neuronal function assessed by carbon-11-hydroxyephedrine.

UNLABELLED: Cardiac toxicity of cocaine has been linked to its inhibitory effect on norepinephrine reuptake by sympathetic nerve terminals of the heart. Carbon-11-hydroxyephedrine is a positron-emitting tracer that has been validated as a highly specific marker for norepinephrine transporter activity of the sympathetic nerve terminals and thus makes possible in vivo assessment of the effect of cocaine on norepinephrine reuptake and storage in the cardiac sympathetic nerve terminals. The aim of the study was to use the catecholamine analog 11C-hydroxyephedrine with PET to determine whether active chronic use of cocaine in women modifies the function of sympathetic nerve terminals of the heart. METHODS: Six normal female volunteers and nine female active chronic cocaine users were studied. Cardiac regional 11C-hydroxyephedrine uptake and blood flow, as assessed with 13N-ammonia, were determined using semi-quantitative polar map analysis of myocardial tracer distribution. Carbon-11-hydroxyephedrine cardiac retention was quantified using dynamic data acquisition and kinetic analysis of blood and tissue activity. RESULTS: Active chronic cocaine users showed small areas of abnormal blood flow and 11C-hydroxyephedrine retention in the heart in comparison with normal volunteers. The extent of abnormalities expressed as a percent of the total polar map area averaged 2.0% +/- 2.6% and 2.5% +/- 2.7% for blood flow and 11C-hydroxyephedrine uptake, respectively. Myocardial 11C-hydroxyephedrine retention was significantly reduced by 22% in active cocaine users (0.109 +/- 0.017 min-1), as compared to normal controls (0.140 +/- 0.027 min-1). CONCLUSION: PET imaging with 11C-hydroxyephedrine permits quantitative assessment of cardiac norepinephrine transporter function in active chronic cocaine users. The results of this study suggest prolonged reduction of norepinephrine uptake and storage capacity in the cardiac sympathetic nerve terminals which may reflect the effect of repetitive elevation of norepinephrine levels induced by cocaine exposure.

Adult↗
PubMed1996

Nicotine and alcohol abuse in African American women who smoke crack cocaine.

The purpose of this descriptive study was to characterize the nicotine and alcohol use of African American women who smoke crack. Particular attention was paid to treatment status and whether treatment influenced perceptions of alcohol addiction and nicotine consumption. Two hundred and eight African American women who smoke crack comprised the convenience sample. One hundred and fifty-two women were in drug treatment, and the rest were "on the streets" still using crack cocaine. In a 3-hr interview, women were asked about their drug and alcohol use, family, and social, health, and drug-related behaviors. All women were administered the CAGE and asked questions about their nicotine use. There were no statistical differences between treatment and nontreatment groups on the CAGE or on smoking. As expected, women in treatment were significantly more likely to report that their behaviors were indicative of an alcohol addiction, although they did not differ from the nontreatment group in potential problems identified by the CAGE.

Adult↗
PubMed1993

Elasticity and geometry measurements of vascular specimens using a high-resolution laboratory CT scanner.

Vascular diseases are frequently associated with changes in the mechanical properties of the arterial wall. Existing techniques for studying arterial geometry and mechanical properties in vitro are often destructive, since they involve sectioning of the specimen into strips, or provide average measurements of the mechanical properties over the volume of intact specimens. We developed a high-resolution computed tomography (CT) scanner for in vitro studies of arterial geometry and static elastic properties. The x-ray image intensifier based system can acquire single transverse images, or a volume image, with 2 mm-1 resolution. Images were obtained through an intact abdominal aortic aneurysm at five pressures. The incremental circumferential Young's modulus E(inc) was calculated from the internal and external circumferences, and at physiological pressures E(inc) of the aneurysm was found to be 275 times greater than that of the normal aorta proximal to it. A volume image of the specimen provided landmarks that allowed histological sections to be obtained at locations coincident with those where the elasticity was measured. The histological analysis revealed a sixfold decrease in elastin content in the aneurysm, compared to the normal aorta. We have demonstrated that the static mechanical properties and geometry of vascular specimens can be quantified in vitro with the new high-resolution CT scanner and can be compared subsequently with histological analysis to provide further insight into the understanding of atherogenesis.

Aged↗
PubMed1993

Ageism within feminism.

Recently there has been heightened interest in linking feminist theory and nursing science. However, neither feminists nor feminist nursing scholars have included aging women in their analyses. This paper analyzes liberal, radical and socialist feminist theories and discusses the gap within all three vis-a-vis aging women. A case is presented for including aging women within feminist thinking and recommendations for incorporating feminist theory and aging within the science of nursing are explicated.

Aged↗
PubMed1991

Expressing antisense P0 RNA in Schwann cells perturbs myelination.

Primary Schwann cells were infected in vitro with a recombinant retrovirus expressing a dominant selectable marker, neomycin phosphotransferase (conferring resistance to the drug G418), and antisense P0 RNA under the control of the human beta-actin promoter. A proportion of the G418-resistant cells failed to form myelin when cocultured with dorsal root ganglion neurons under conditions that promote Schwann cell differentiation. These cells expressed high levels of P0 antisense RNA. Among the impaired cells, the majority had segregated and ensheathed individual axon but had not differentiated further. They did not express P0 but did express myelin- associated glycoprotein and galactocerebroside. A minority of partially inhibited Schwann cells were also observed that elaborated thin myelin sheaths containing variable numbers of compacted and noncompacted lamellae. These data indicate that restricting the level of P0 expression inhibits spiralling of the Schwann cell membrane and subsequent compaction.

Animals↗
PubMed1991

Comparative hemodynamic effects of halothane and halothane-acepromazine at equipotent doses in dogs.

The purpose of this study was to compare the cardiovascular effects of halothane when used alone at increasing doses (1.2, 1.45 and 1.7 minimum alveolar concentration, MAC) to those produced with equipotent doses of halothane after potentiation of the anesthetic effect with acepromazine (ACP) sedation (45% reduction of halothane MAC). Six healthy mature dogs were used on three occasions. The treatments were halothane and intramuscular (IM) saline (1.0 mL), halothane and ACP (0.04 mg/kg IM), or halothane and ACP (0.2 mg/kg IM). Anesthesia was induced and maintained with halothane in oxygen and the dogs were prepared for the collection of arterial and mixed venous blood and for the determination of heart rate, systolic, diastolic and mean arterial pressure, mean pulmonary arterial pressure (PAP), central venous pressure and cardiac output. Following animal preparation the saline or ACP was administered and positive pressure ventilation instituted. Twenty-five minutes later the dogs were exposed to the first of three anesthetic levels, with random assignment of the sequence of administration. At each anesthetic level, measurements were obtained at 20 and 35 min. Calculated values included cardiac index, stroke index, left ventricular work, systemic vascular resistance, arterial oxygen content, mixed venous oxygen content, oxygen delivery and oxygen consumption. Heart rate was significantly higher with halothane alone than with both halothane-ACP combinations and was significantly higher with high dose ACP compared to low dose ACP. Systolic and mean blood pressures were lowest with halothane alone and highest with 0.2 mg/kg ACP, the differences being significant for each treatment. Oxygen uptake and PAP were significantly lower in dogs treated with ACP. It was concluded that ACP does not potentiate the cardiovascular depression that accompanies halothane anesthesia when the resultant lower dose requirements of halothane are taken into consideration.

Acepromazine↗
PubMed1990

Prophylactic use of dantrolene associated with prolonged postanesthetic recumbency in a horse.

Dantrolene, a drug used in the prevention and treatment of malignant hyperthermia, was believed responsible for prolonged postanesthetic recumbency in a horse. Prophylactically, dantrolene was given orally before induction of anesthesia. Dantrolene has been recommended for use in horses at risk of developing postanesthetic myopathy. Side effects, including ataxia, may result from dantrolene administration.

Animals↗
PubMed1990

Drug use, health, family and social support in "crack" cocaine users.

The purpose of this study was to explore and describe "crack" cocaine use, health, family and social support in adult users. A nonprobability, convenience sample was used comprising 100 inpatients, 77 men and 23 women, from a drug treatment program. Gender differences, though not found in areas related to drug consumption, were found with respect to where and with whom subjects smoked, as well as perceptions of significant others. This initial, exploratory study should provide a foundation for future investigations concerning crack cocaine users.

Adolescent↗
PubMed1990

Expression of recombinant myelin-associated glycoprotein in primary Schwann cells promotes the initial investment of axons by myelinating Schwann cells.

Myelin-associated glycoprotein (MAG) is an integral membrane protein expressed by myelinating glial cells that occurs in two developmentally regulated forms with different carboxyterminal cytoplasmic domains (L-MAG and S-MAG). To investigate the role of MAG in myelination a recombinant retrovirus was used to introduce a MAG cDNA (L-MAG form) into primary Schwann cells in vitro. Stably infected populations of cells were obtained that constitutively expressed MAG at the cell surface without the normal requirement for neuronal contact to induce expression. Constitutive expression of L-MAG did not affect myelination. In long term co-culture with purified sensory neurons, the higher level of MAG expression on infected Schwann cells was reduced to control levels on cells that formed myelin. On the other hand, unlike normal Schwann cells, infected Schwann cells associated with nonmyelinated axons or undergoing Wallerian degeneration expressed high levels of MAG. This suggests that a posttranscriptional mechanism modulates MAG expression during myelination. Immunostaining myelinating cultures with an antibody specific to L-MAG showed that L-MAG was normally transiently expressed at the earliest stages of myelination. In short term co-culture with sensory neurons, infected Schwann cells expressing only L-MAG segregated and ensheathed larger axons after 4 d in culture provided that an exogenous basal lamina was supplied. Similar activity was rarely displayed by control Schwann cells correlating with the low level of MAG induction after 4 d. These data strongly suggest that L-MAG promotes the initial investment by Schwann cells of axons destined to be myelinated.

Animals↗