Liver preservation with machine perfusion and a newly developed cell-free oxygen carrier solution under subnormothermic conditions.

We describe a new preservation modality combining machine perfusion (MP) at subnormothermic conditions(21 °C) with a new hemoglobin-based oxygen carrier (HBOC) solution. MP (n=6) was compared to cold static preservation (CSP; n=6) in porcine orthotopic liver transplants after 9 h of cold ischemia and 5-day follow-up. Recipients' peripheral blood, serial liver biopsies, preservation solutions and bile specimens were collected before, during and after liver preservation. Clinical laboratorial and histological analyses were performed in addition to mitochondrial functional assays, transcriptomic, metabolomic and inflammatory inflammatory mediator analyses. Compared with CSP, MP animals had: (1) significantly higher survival (100%vs. 33%; p<0.05); (2) superior graft function (p<0.05);(3) eight times higher hepatic O2 delivery than O2 consumption (0.78 mL O2/g/h vs. 0.096 mL O2/g/h) during MP; and (4) significantly greater bile production (MP=378.5 ± 179.7; CS=151.6 ± 116.85). MP downregulated interferon (IFN)-α and IFN-γ in liver tissue. MP allografts cleared lactate, produced urea, sustained gluconeogenesis and produced hydrophilic bile after reperfusion. Enhanced oxygenation under subnormothermic conditions triggers regenerative and cell protective responses resulting in improved allograft function. MP at 21 °C with the HBOC solution significantly improves liver preservation compared to CSP.

Localization of prostaglandin H synthase, prostaglandin dehydrogenase, corticotropin releasing hormone and glucocorticoid receptor in rhesus monkey fetal membranes with labor and in the presence of infection.

Prostaglandins (PGs) play a central role in primate parturition by their actions on uterine contractility and on cervical ripening. Rhesus monkey placentation is hemochorial and the endocrine events surrounding parturition are qualitatively similar to human pregnancy. Although there is an increase in PG production before the onset of labor, little is known about the cellular localization of the PGH synthase (PGHS) or the 15-hydroxy PG dehydrogenase (PGDH) in the fetal membranes of nonhuman primates and whether it changes at term in spontaneous labor or during preterm labor associated with infection. Placental corticotropin releasing hormone (CRH) and the glucocorticoid receptor (GR) have also been implicated as mediators in parturition by virtue of their roles in PG production. We utilized immunohistochemical methods to localize the inducible isoform PGHS-2, PGDH, GR and CRH in rhesus monkey amnion, chorion and attached decidua. Tissues were obtained at cesarean section during late pregnancy, in spontaneous labor at term and in premature labor induced by Group B streptococcal intraamniotic infection. Specific staining for immunoreactive (ir)-PGHS-2 was observed in amnion epithelial and mesenchymal cells and to a lesser extent in chorion and decidua. In contrast, ir-PGDH was localized primarily to the extravillous trophoblast layer of chorion. GR was localized to both the cytoplasm and nucleus of amnion epithelial cells, subepithelial fibroblasts, chorion trophoblasts and in decidua. Immunostaining for CRH was found in amnion and in scattered decidual cells but was most intense in the chorion trophoblast layer. There was no demonstrable change in this overall pattern of immunostaining in association with the onset of labor at term except for a decrease in staining for ir-PGDH in chorion. Experimental Group B streptococcal chorioamnionitis resulted in preterm labor and extensive necrosis of extravillous trophoblast cells with subsequent loss of chorionic ir-PGDH and relative sparing of ir-PGHS-2 in amnion epithelium which favors the net production of PGs. The expression pattern of these effectors in the rhesus monkey fetal membranes points to a functional role of PGs and glucocorticoids in the process of term and preterm parturition which is similar to that in human pregnancy.

Lack of effect of melatonin on myometrial electromyographic activity in the pregnant sheep at 138-142 days gestation (term = 147 days gestation).

A 24-h rhythm has been demonstrated in fetal and maternal melatonin plasma concentrations in pregnant sheep in the last third of gestation. Melatonin in the maternal circulation can cross the placenta and is the major source of melatonin in the fetal circulation. Melatonin has been postulated to act as a prostaglandin (PG) synthetase inhibitor in the uterus. PG synthetase inhibitors decrease myometrial contractility. To assess transplacental passage of melatonin and potential influences of melatonin on uterine contractility, we infused melatonin continuously into the maternal jugular vein in seven pregnant sheep at 138-142 days gestation (term in our instrumented animals is 147 days gestation) at three infusion rates for successive 1-h periods during the late morning to late afternoon. There was no change in the total time during which the myometrium was active, as indicated by myometrial electromyographic activity or the myometrial contracture frequency during the 3 h before and after melatonin infusions and for each hour of the infusions. The MCR for melatonin in the ewe was 4128 +/- 410 ml/min (mean +/- SE; n = 7; weight, 50-70 kg). The resting maternal to fetal melatonin concentration ratio was 0.8; this ratio was maintained at 2.28 during melatonin infusion to the ewe at a wide range of maternal melatonin concentrations. Melatonin concentrations in the range of 3-200 times normal had no effect on the maternal plasma PGF2 alpha metabolite concentration, but caused a 40.4% fall in fetal plasma PGE2 (P less than 0.05). We conclude that changes in maternal and fetal plasma melatonin concentrations within the physiological range observed throughout the day do not alter myometrial contractility, but do alter fetal PGs.

Maintaining fetal normoglycemia prevents the increase in myometrial activity and uterine 13,14-dihydro-15-keto-prostaglandin F2 alpha production during food withdrawal in late pregnancy in the ewe.

Food deprivation during pregnancy leads to an increase in maternal and fetal prostaglandin (PG) production and increased uterine contractility. We investigated the effect of maintaining fetal normoglycemia during food withdrawal-induced maternal hypoglycemia on uterine 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) production and myometrial activity in late pregnant sheep. Pregnant sheep were surgically instrumented with fetal and maternal catheters and electromyogram leads under halothane anesthesia. Maternal and fetal blood plasma samples were obtained once a day at 0900 h, 24 h before (baseline sample) and after 48 h of food withdrawal. Food, but not water, was withdrawn from ewes in group I (n = 5). During food withdrawal in group II (n = 5), glucose was infused into a fetal vein to maintain fetal normoglycemia. All data were normalized to the concentration in the baseline sample in each animal as 100%. After 48 h of food withdrawal, maternal whole blood glucose fell by 42.2 +/- 4.4% (mean +/- SEM: group I) and 31.4 +/- 6.2% (group II). These values were not significantly different. Fetal blood glucose fell by 40.4 +/- 5.7% (group I). In group II, fetal blood glucose was maintained in the normal range (99.6 +/- 1.6% of baseline). Maternal uterine electromyogram activity, uterine venous estrone sulfate, and uterine veno-arterial difference in PGFM rose significantly during food withdrawal in group I ewes, but not in group II ewes. Maternal and fetal arterial plasma ACTH and cortisol did not change in group II animals. We conclude that maintenance of fetal normoglycemia during 48 h of food withdrawal in sheep prevents the increase in myometrial activity, maternal plasma estrogens, and uterine PGFM production during food withdrawal in late pregnancy.

Prostaglandin endoperoxide-H synthase (PGHS) activity and immunoreactive PGHS-1 and PGHS-2 levels in human amnion throughout gestation, at term, and during labor.

Prostaglandins (PGs) are of primary importance in the initiation and maintenance of labor in women. A major intrauterine source of prostaglandins is the amnion, which synthesizes increased amounts of PGE2 at term labor. Because PG endoperoxide-H synthase (PGHS) catalyzes the rate-limiting step of PG synthesis from arachidonic acid, we investigated the changes in amniotic PGHS specific activity during gestation and at term and preterm labor. Also, we determined the level of immunoreactive PGHS protein in the amnion to evaluate the mechanisms by which PGHS activity may be regulated. PGHS specific activity, measured at the amount of PGE2 produced by amnion microsomes under optimal conditions, was 18.2 +/- 3.7 pg PGE2/micrograms protein.min (mean +/- SE; n = 19) at term (37-42 weeks gestation) before the spontaneous onset of labor. PGHS specific activity was significantly higher after spontaneous term labor (38.9 +/- 6.0 pg PGE2/micrograms protein.min; n = 19; P < 0.05). Amnion samples from preterm (< 36 weeks gestation) nonlaboring patients contained low levels of PGHS specific activity (5.9 +/- 1.8 pg PGE2/micrograms protein.min; n = 9), which increased significantly with spontaneous preterm labor (28.3 +/- 6.8 pg PGE2/micrograms protein.min; n = 10; P < 0.05). Longitudinal analysis of the data showed that PGHS specific activity was low in the first and second trimesters of gestation, but increased dramatically before labor onset at term. We detected PGHS protein in all microsomal samples, with an antiovine PGHS antibody recognizing both PGHS-1 and -2 isoforms of the enzyme. However, there was no correlation between PGHS specific activity and the amount of immunoreactive PGHS protein. Using an antibody specific for PGHS-2, we detected immunoreactive protein in only 9 of the 25 tissues examined and found no correlation between PGHS specific activity and the amount of PGHS-2 protein. These results suggest that 1) PGHS specific activity in the amnion increases sharply before the onset of labor at term; 2) further increases in specific activity occur during term and preterm labor; and 3) the specific activity of PGHS in the amnion is not related directly to the amount of immunoreactive enzyme protein.

A model predicting dentists' willingness to treat HIV-positive patients.

Data for this study of dentists' willingness to treat HIV-positive (HIV+) individuals were derived from a survey of a probability sample of American general practitioner dentists (GPD). Data were received from 1,351 active GPD, which represented an 88% response rate. Because the outcome measure--willingness to treat HIV+ patients--is dichotomous, i.e., yes/no, logistic regression was selected as the statistical technique to be used for the creation of a predictive model. Seventeen independent variables were initially considered. The final and most parsimonious model contains six independent variables, of which perceived safety in treating HIV+ patients has the most predictive power. Fear of consequences for the practice, if HIV+ patients were seen, was also a powerful predictor, with a sense of ethical responsibility and a past history of treating HIV+ patients also being important predictive variables. Knowledge level about transmission of HIV and concern about risks associated with treating homosexuals were also significant.

Effect of maternal cocaine administration on maternal and fetal glucose, lactate, and insulin in sheep.

Although cocaine use during pregnancy is an important cause of perinatal morbidity and mortality, there are no reports of its effect on maternal and fetal carbohydrate metabolism. Six pregnant ewes and their fetuses were instrumented under halothane general anesthesia at 113-119 days' gestation. Between 124-135 days' gestation, the ewes received a single infusion of vehicle or cocaine (1.0 or 2.0 mg/kg) into the jugular vein. At least 24 hours was allowed between successive injections. Maternal and fetal blood samples were drawn at 30 and 20 minutes before and at 5, 15, 30, and 60 minutes after the injection. Both maternal and fetal glucose and lactate concentrations increased (P less than .05) after injection of cocaine at 2.0 mg/kg. There were no significant changes in maternal or fetal plasma insulin concentrations after vehicle or cocaine administration. Induction of hyperglycemia and lactacidemia could be mechanisms whereby cocaine exerts its adverse effects during pregnancy.

Lack of effect of maternal cocaine administration on myometrial electromyogram and maternal plasma oxytocin concentrations in pregnant sheep at 124-146 days' gestational age.

Although cocaine abuse during human pregnancy is associated with an increased incidence of preterm labor, there are few reports on the effects of cocaine on myometrial activity during pregnancy in experimental animals. Cocaine (0.5, 1, or 2 mg/kg) or vehicle was randomly administered intravenously to 15 pregnant ewes between 124-146 days' gestation (term is 147 days). Neither cocaine nor vehicle administration altered total myometrial electromyographic activity from pre-dose levels 1 or 6 hours after administration. Maternal arterial plasma oxytocin did not change during the study. Using a positive control, we confirmed observations of other investigators that administration of 2 mg/kg cocaine significantly increases maternal arterial blood pressure. The results indicate that cocaine does not stimulate myometrial contractility significantly in late pregnancy in sheep.

Correlation between population density and the frequency of Creutzfeldt-Jakob disease in France.

Epidemiologic studies of Creutzfeldt-Jakob disease (CJD) in countries throughout the world have consistently shown higher urban than national disease frequencies, but this finding has usually been ascribed to case-finding artefact. A detailed analysis has now been completed of annual mortality rates of CJD in France, based on a systematic study of 255 consecutive cases dying during the period 1968-1980, of whom 85 resided in the paris metropolitan area. In the country as a whole, the frequency of CJD increased from rural, through urban, to the Paris region; and in the Paris region, the frequency increased from the lowest to the highest density areas. The magnitude of this positive correlation between population density and the frequency of CJD is not explained by differences in age distribution of the various population groups, and suggests a role for random inter-human spread, either direct or indirect, in natural disease transmission.

Control of human parturition.

Parturition is a process that is composed of five separate and distinct physiological components but which lead from one to the next and are, therefore, interdependent. As such, the regulation of myometrial contractility should not be examined in isolation but as part of this continuum. The initiation of labor begins with the biochemical events that result in the rupture of the fetal membranes, effacement of the cervix, and the switch from contractures to contractions. Because we have defined being in labor as the point at which contractions no longer revert to contractures, we suggest that labor is superimposed upon pregnancy in humans and nonhuman primates. There is no withdrawal or retreat from pregnancy, and no evidence exists that the concentrations or actions of progesterone diminish at term. Rather, the target tissues of labor are activated to perform their physiological functions, and these functions are initiated by stimulators. The best candidate for achieving activation is maternal estrogen, derived from fetal DHEAS, but major gaps in our knowledge of this process still exist. Prostaglandins are the most likely candidates as the stimulators of labor initiation, but close inspection of their precise roles also demands that clearer definition of their synthesis and actions be acquired. Coordination of and communication between the physiological events of labor motivates us to examine nontraditional mediators such as cytokines for their potential roles in the regulation of these events at normal term.

Effect of pulsatile intravenous oxytocin administration to pregnant sheep over the last third of gestation on fetal ACTH and cortisol responses to hypotension.

OBJECTIVE: To examine the effect of increasing myometrial contractility in the last third of gestation on ovine fetal response to hypotension. METHODS: Oxytocin (600 microU/kg/minute) or saline was infused via the maternal jugular vein as 5-minute pulses every 20 minutes, starting at 97 +/- 1 days of gestational age (mean +/- standard error of the mean) until labor. Fetal hypotension (10 minutes) was induced by intravenous nitroprusside infusion at 133 +/- 1 days' gestation. RESULTS: Ewes from both groups went into labor at the same gestational age. Total fetal body and adrenal gland weights were higher in controls than in the oxytocin-treated group. Maternal arterial pH and blood gas values were normal throughout the study. At 132-136 days' gestation, fetal arterial oxygen pressure was lower in the oxytocin group than in controls (P < .05). Basal fetal ACTH concentrations did not change between 130 and 136 days in both groups. The mean fetal plasma ACTH concentration was not different between the control (40.6 +/- 4.1 pg/mL) and oxytocin groups (32.6 +/- 4.9 pg/mL). Pre-hypotension fetal plasma ACTH was similar in both groups, whereas cortisol was lower in the oxytocin group. Hypotension significantly increased fetal plasma ACTH and cortisol concentrations; however, both ACTH and cortisol responses were smaller in the oxytocin group (P < .05). CONCLUSIONS: Increased myometrial contractility throughout the last third of gestation modifies the normal ACTH and cortisol relation at the critical time of prepartum increase in adrenocortical activity. In addition, fetal ACTH and cortisol responses to hypotension are diminished in fetuses exposed to such a prolonged increase in myometrial contractility. These observations support the hypothesis that myometrial contractility influences fetal neuroendocrine development.

Activation of the fetal hypothalamic-pituitary-adrenal axis with prolonged and graded hypoxemia.

OBJECTIVE: The purpose of this study was to determine whether activation of the hypothalamic-pituitary-adrenal (HPA) axis and uteroplacental prostaglandin (PG) response occur before metabolic deterioration with a progressive decrease in fetal oxygenation. METHODS: Twenty-one chronically catheterized fetal sheep were studied between 126 and 135 days' gestation during a 24-hour normoxic control period and subsequently during 4 experimental days of either prolonged and graded hypoxemia, induced by progressively lowering the maternal inspired oxygen concentration (induced hypoxia, n = 12), or continued study on room air (control, n = 6; spontaneous hypoxia, n = 3). Fetal arterial blood was sampled daily for blood gases and pH, immunoreactive ACTH, cortisol, and PGE2. Placental cotyledons were obtained at the end of the experiment for measurement of prostaglandin-H synthase (PGHS) enzymatic activity. RESULTS: For all hypoxia group measurements, progressive reduction in fetal oxygenation resulted in little change in either plasma ACTH or cortisol until arterial O2 saturation was close to 30% with metabolic acidosis onsetting. This was in keeping with activation of the HPA axis at this time, because ACTH and cortisol values showed a strong linear correlation (r = 0.77, P < .01). Fetal plasma PGE2 concentrations and cotyledonary PGHS enzymatic activity, although somewhat higher in the hypoxia group animals, were not changed significantly. CONCLUSION: In response to prolonged and graded hypoxemia in the ovine fetus, activation of the HPA axis occurs only when the degree of hypoxemia is pronounced and close to that associated with metabolic deterioration, which may limit the time for any uteroplacental response and the ability to initiate labor.

Effect of pulsatile oxytocin administration to the pregnant ewe in the last third of gestation on fetal ACTH and cortisol response to acute hypoxemia.

OBJECTIVE: The aim of this study was to examine the effect of increased myometrial contractility throughout the last third of pregnancy on the ovine fetal response to short-term hypoxemia. METHODS: Oxytocin (600 microU/kg/minute, n = 5) or saline (n = 7) was infused for 5 minutes every 20 minutes into the maternal jugular vein starting at 95-99 days of gestation and continuing throughout the last third of gestation. Fetuses were subjected to a hypoxemic challenge (1 hour) at 131 days of gestation while fetal plasma ACTH and cortisol levels and nuchal muscle electromyogram activity were monitored. RESULTS: The fetal plasma ACTH concentration before and during the hypoxemic challenge was similar in the control and oxytocin groups. The fetal plasma cortisol concentration in the oxytocin group was significantly lower before and during the hypoxemia than in the controls. During hypoxemia, fetal nuchal muscle activity was significantly reduced only in the control group. CONCLUSION: Increased myometrial contracture frequency throughout the last third of pregnancy alters both the neuroendocrine and behavioral responses of fetal sheep to short-term hypoxemia.

Progesterone receptor localization and isoforms in myometrium, decidua, and fetal membranes from rhesus macaques: evidence for functional progesterone withdrawal at parturition.

OBJECTIVE: It is not known whether withdrawal of progesterone (P) action is a prerequisite for parturition in women or in nonhuman primates because concentrations of circulating progesterone or progesterone receptors (PR) in myometrium and decidua do not decrease before delivery. To examine this potentially important regulatory mechanism, we determined PR isoforms, PR localization, and mRNA in myometrium, decidua, and fetal membranes from rhesus monkeys during pregnancy and in spontaneous labor at term. METHODS: Gestational tissues were obtained midpregnancy (day 80-100), late pregnancy (day 130-145), and during spontaneous labor at term (day 161-167). Samples of rhesus monkey myometrium, decidua, chorion-decidua, and amnion were collected and analyzed for total nuclear and cytosolic PR by competitive binding assay. Progesterone receptor isoforms were identified and quantified by Western blot analysis, and PR mRNA was determined by a specific ribonuclease protection assay. Nuclear PR was localized by immunohistochemistry with monoclonal anti-PR (JZB39) after microwave stabilization. RESULTS: Myometrium and decidua showed no change in total PR during pregnancy and labor. Nuclear PR was not detected in fetal membranes by binding assay but was localized in amnion epithelial and mesenchymal cells and in chorion laeve cytotrophoblasts by immunohistochemistry. Staining for PR was substantially less by serial antibody dilution in fetal membranes than in decidua. Message for PR was confirmed in all tissues analyzed. A significant (P <.05) shift in the ratio of PR isoforms (from PR-B dominance at midpregnancy to PR-A dominance in labor) was observed in myometrium but not in decidua. Both PR-A and PR-B isoforms and PR nuclear staining were nearly undetectable in amnion obtained during labor. CONCLUSION: A shift to PR-A dominance in myometrium at term together with a loss of PR in fetal membranes provides evidence for a functional progesterone withdrawal mechanism, which may facilitate the initiation of parturition in primates.

Professional life cycle changes and their effect on knowledge level of dental practitioners.

Utilizing a national data set (U.S.A.), the effect of age and age-related professional characteristics on dentists' knowledge with regard to prevention of infective endocarditis was examined. The following research questions were addressed: (1) Do age-related characteristics produce different effects on knowledge level at various stages of professional careers?; (2) What are the key changes in these age-related characteristics and what processes are suggested by these changes? Multiple regression analysis assessed the influence of potential predictors of variation in knowledge level with regard to prevention of infective endocarditis for the entire sample. Using these findings as a guide, variation in the effect of significant predictor variables was then analyzed for three time segments of approximately equal duration: early professional life less than 40, mid-professional life 40-54, and older professional life 55 or greater than. Age had a profoundly negative effect on knowledge level, i.e. the level progressively declines as clinicians grow older. The impact of the age-related characteristics on knowledge level of infective endocarditis prevention also varied according to the stage of the professional life cycle. Indices measuring the size or extent of theoretical understanding, in-office networks, institutional affiliations, and consulting networks were significant predictors of endocarditis prevention knowledge for younger clinicians. For those 40-54, only practice organization (office business and staff size and diversity) was a significant predictor, while for older clinicians theoretical understanding was the only significant predictor. Differences in the mean levels of these predictor (independent) variables across age groups were also examined via ANOVA.(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting dentists' perceived occupational risk for HIV infection.

This study posed two questions: what is the level of perceived occupational risk among American general practice dentists (GPDs)? What factors influence perception of occupational risk for HIV infection among GPDs? In data obtained from a national mail survey of 1351 GPDs (response rate, 88%) 31% of American GPDs expressed disagreement with the statement that HIV+ individuals can be safely treated in their office settings. Of the 16 variables entered into a multiple regression equation, 9 variables had a statistically significant influence on dentists' assessment of occupational risk. In order of their influence they were (1) concern re the economic viability of the practice, (2) ethical obligation to treat patients at risk, (3) certainty of having treated patients with HIV infection, (4) risk attributed to four accidental occupational exposures, (5) concern re treatment of homosexuals, (6) relevant continuing education exposure, (7) personal worry re transmission of HIV infection from patients, (8) implementation of infection control behaviors, (9) number of patients seen per week. Statistically nonsignificant predictors of interest included age, knowledge level re HIV transmission routes, practice location in a high prevalence area, and perceived effectiveness of infection control behaviors. Results argue for intervention programs with less focus on delivery of factual information regarding the transmission of the disease and the effectiveness of infection control techniques, and more emphasis on the themes of practice economic viability, professional ethics, and structured educational encounters involving dentists' knowing exposure to HIV-infected patients.

Predictors of dentists' level of knowledge regarding the recommended prophylactic regimen for patients with rheumatic heart disease.

Maintaining knowledge of clinical practices, conforming to the latest scientific information, is a major challenge for health professionals. The study aims were to measure clinicians' knowledge and to determine what social factors could best explain and predict those dental clinicians who are most knowledgeable about current expert recommendations for the use of appropriate antibiotic regimens for patients at risk for bacterial endocarditis. Telephone interviews were conducted with 322 New York State dentists, assigned to the study by a computer-generated randomization procedure from lists of oral surgeons, urban general practitioners and rural general practitioners. Data demonstrated extraordinary differences in level of knowledge between oral surgeons and general practitioners, while the level of knowledge between urban and rural general practice groups was quite similar. General Linear Model (GLM)-based analyses indicated that practice size, rationalization of practice, and practice setting and affiliations contributed to the explanation of knowledge level among general practitioners, when adjusted for age. R2s for each of those variables and age, ranged from a low of 0.132 to a high of 0.334. Age made a significant contribution to the explanation of knowledge level in all of the models presented, while the explanatory power of the practice structure variables varied according to respondent's locale (urban vs rural) and age (younger vs older). In order to assess the impact of these structural variables, they were dichotomized (high-low) and entered into a GLM program which accounted for age and locale. Differences in excess of 20 points (on a 0-100 knowledge scale) were sometimes noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences between Asian-American and white American dentists in attitudes toward treatment of HIV-positive patients.

In a survey of Asian (n = 115) versus white (Caucasian) (n = 920) dentists practicing in two boroughs of New York City, Asian dentists expressed significantly more negative attitudes toward and more unwillingness to treat HIV-positive patients than did white dentists. Despite this consistent pattern across most survey items, the two groups were more similar regarding perceptions of professional obligation and their colleague's willingness to treat those with HIV. In an examination of the influence of acculturation processes on these attitudes, a comparison of attitude differences among the subgroup of Asian dentists receiving their dental education in the United States versus abroad showed some differences, with Asian dentists educated outside the United States expressing somewhat more negative attitudes. As Asian Americans become increasingly represented among practicing dentists in the United States, their relative unwillingness to treat HIV-positive patients may have an impact on access to oral health care among HIV-positive persons living in the United States.

Knowledge acquisition processes: dissemination of expert recommendations to general practice dentists.

We examined structural determinants of general practice dentists' knowledge of the most recent American Heart Association recommendations for the prevention of bacterial endocarditis. Using data from a 1986 national telephone survey of 578 respondents (response rate = 81%), we developed and analyzed a structural model, in which we investigated the contributions to knowledge by age, professional practice settings, colleague networks, and formal educational experiences. Age, practice organization, and institutional affiliations are direct contributors to knowledge. Formal professional channels of reeducation do not contribute directly to knowledge level; rather, their effect is expressed through institutional affiliations.

Toward a typology of preventively oriented dentists.

This study identifies predictors of preventive behavior among dental general practitioners in New York State. A total of 217 clinicians was interviewed by telephone. Dentists practicing in an urban area (n = 120) and in a rural area (n = 97) were studied. A unit-weighted index of clinician preventive orientation was created, by summing z-score values for two preventive variables: the number of content items and the number of patient visits in an organized preventive program that entailed more than one visit. Multiple regression of this preventive orientation index on selected independent variables showed that, for the entire sample, variables representing involvement in academic and institutional dentistry, exposure to education through journals and courses, a predeliction for innovation, and the presence of a hygienist in the office, were most influential in creating a model that successfully predicted reported preventive behavior. Differences between urban and rural clinicians in predictors of preventive behavior are also identified. Data collected are compared with those of four previous studies that attempted to describe potential predictors of preventive behavior in dentists.