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Biomedical subjects

R Baldwin

Publications and source records attributed to R Baldwin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Accuracy of CT biopsy: laser guidance versus conventional freehand techniques.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine whether laser-guided computed tomographic (CT) biopsy is more accurate than CT-guided biopsy with conventional freehand techniques. MATERIALS AND METHODS: Two independent operators performed an equal number of freehand and laser-guided needle passes at varying single and double angles (0 degree, 30 degrees, 60 degrees, 25 degrees/30 degrees, and 25 degrees/60 degrees) on targets within six pork and beef phantoms. A total of 180 biopsy passes were performed, and error distances of needle tip to target were tabulated. Data were analyzed by means of repeated measures analysis of variance (ANOVA) to compare the accuracy of laser guidance with freehand passes. ANOVA and correlation analysis were also used to confirm the relative equivalency of phantom targets and biopsy parameters. RESULTS: Overall, laser-guided passes were statistically significantly more accurate than freehand passes. Mean error with laser guidance was 5.01 mm (standard error [SE] = 0.41 mm), whereas mean error with freehand techniques was 10.58 mm (SE = 0.82 mm) (F = 52.0, df = 1.17, P = .0001). Ninety-three percent of laser-guided passes and 56% of freehand passes were within 1 cm of the intended target. Error increased for both laser-guided and freehand techniques with larger angles or double-angle biopsies, but the increases were greater with freehand technique. No statistically significant differences existed between the targets themselves or biopsy parameters for the two operators. CONCLUSION: Laser-guided CT biopsies were more accurate than freehand CT biopsies. Practical advantages of laser guidance over freehand CT biopsy methods may include decreased procedure times and reduced patient morbidity.

Animals↗
PubMed1996

Brain organization in a reptile lacking sex chromosomes: effects of gonadectomy and exogenous testosterone.

In mammals, males and females differ both genetically and hormonally, making it difficult to assess the relative contributions of genetic constitution and fetal environment in the process of sexual differentiation. Many reptiles lack sex chromosomes, relying instead on the temperature of incubation to determine sex. In the leopard gecko (Eublepharis macularius), an incubation temperature of 26 degrees C produces all females, whereas 32.5 degrees C results in mostly males. Incubation temperature is the primary determinant of differences both within and between the sexes in growth, physiology, and sociosexual behavior, as well as the volume and metabolic capacity of specific brain nuclei. To determine if incubation temperature organizes the brain directly rather than via gonadal sex hormones, the gonads of male and female leopard geckos from the two incubation temperatures were removed and, in some instances, animals were given exogenous testosterone. In vertebrates with sex chromosomes, the size of sexually dimorphic nuclei are sensitive to hormone levels in adulthood, but in all species studied to date, these changes are restricted to the male. Therefore, after behavior tests, morphometrics of certain limbic and nonlimbic brain areas were determined. Because nervous system tissue depends on oxidative metabolism for energy production and the level of cytochrome oxidase activity is coupled to the functional level of neuronal activity, cytochrome oxidase histochemistry also was performed on the same brains. Hormonal manipulation had little effect on the volume of the preoptic area or ventromedial hypothalamus in geckos from the all-female incubation temperature, but significantly influenced the volumes of these brain areas in males and females from the male-biased incubation temperature. A similar relationship was found for cytochrome oxidase activity of the anterior hypothalamus, amygdala, dorsal ventricular ridge, and septum. The only sex difference observed was found in the ventromedial hypothalamus; males showed no significant changes in cytochrome oxidase activity with hormonal manipulation, but females from both incubation temperatures were affected similarly. The results indicate that incubation temperature organizes the brain directly rather than via hormones arising from its sex-determining function. This is the first demonstration in a vertebrate that factors other than steroid hormones can modify the organization and functional activity of sexually differentiated brain areas.

Animals↗
PubMed1996

What are outcomes?

Understanding the important aspects of measuring outcomes will prepare pharmacists for changes in the marketplace and help them to assess the results of studies that will appear in subsequent issues of the Journal of the American Pharmaceutical Association and the research journals of other health services professions. In any evaluation of quality, all three quality measures (structure, process, and outcomes) must be considered. No one measure, in isolation, can describe the quality of care provided. Thus, the best patient care will come from health care practitioners who document structure, process, and outcomes and who evaluate these measures to provide appropriate care. The pharmacist cannot dispense prescriptions or provide pharmaceutical care without a pharmacy, drug inventory, or patient profiles, all of which are important structural inputs. The pharmacist takes a medication history, monitors the drug regimen, and counsels the patient on the appropriate way to use the treatment, all vital process activities. The objective of these inputs and actions is to improve the health status of the patient. Outcomes, therefore, are the intended endpoints of care, and occasional unintended effects (e.g., adverse drug reactions) as well. The future of pharmacy rests on demonstrating the positive effect of pharmaceutical care on patient outcomes. Pharmacists have always been part of the system of checks and balances in health care delivery. As the provision of health services changes, opportunities to assess the process and structure of care and to document patient outcomes will increase. Pharmacists are well positioned to intervene in patient care, but if they do not demonstrate the value of pharmacy services, they will face competition from alternative providers. Some have even suggested less expensive alternatives to having pharmacists dispense medications. Pharmacists must establish that their role goes beyond dispensing to include cognitive services such as compliance programs, screening services, glucose monitoring, and disease management programs. Pharmacists must document their role and its effects on patient outcomes.

Humans↗
PubMed1996

[Treatment of hypertension with indapamide 1.5 mg sustained-release form: synthesis of results].

In accordance with international recommendations on the need to decrease doses of antihypertensive drugs, a low-dose (1.5 mg) sustained-release form of indapamide was developed so as to optimize the safety/efficacy ratio, while maintaining a once-daily administration. The new formulation ensures that the active ingredient release occurs in a sustained manner over 24 hours, with mean concentrations close to the maximal concentration over a prolonged period, while avoiding peak plasma concentrations. Clinical data were obtained mainly through two European multicenter, randomized, double-blind trials, totalling 690 patients. Firstly, the antihypertensive efficacy' of the new indapamide 1.5 mg form was demonstrated by measuring blood pressure 24 hours after the last drug intake, using a mercury sphygmomanometer; the equivalence of its antihypertensive efficacy with the immediate-release form of indapamide 2.5 mg was then verified. Biochemical safety data showed better acceptability with indapamide 1.5 mg with in particular a reduction of more than 50% of the number of patients with kalemia < 3.4 mmol/l; clinical safety data confirmed the good acceptability observed with the 2.5 mg immediate-release form of indapamide since many years, especially regarding glucose and lipid neutrality. In conclusion, the 1.5 mg sustained-release form of indapamide has an improved antihypertensive efficacy/safety ratio which is in accordance with international recommendations for the usage of low doses of antihypertensive drugs and diuretics in the first-line treatment of hypertension.

Adolescent↗
PubMed1994

Diversity of ethnic and racial VNTR RFLP fixed-bin frequency distributions.

To examine the impact that intra- and interracial genetic diversities have on VNTR RFLP-fragment-size distributions, a multiracial (East Asian, African American, U.S. Southwest Hispanic, and European Caucasian) and multiethnic (Chinese, Japanese, Korean, and Vietnamese) database has been constructed for the following loci: D1S7, D2S44, D4S139, and D10S28. Homogeneity between samples was examined using the Komologorov-Smirnov two-sample test for RFLP fragment sizes and a log-likelihood test for fixed-bin frequencies with theoretical and Monte Carlo empirical significance levels. Small but significant differences between theoretical and empirical significance-level distributions were observed with both procedures, particularly with the latter. The significance levels of the two types of tests were poorly correlated. Statistically significant differences in fragment-size and fixed-bin distributions were found within and between races, with greater differences occurring between races. Cluster analysis and principal components analysis, using different similarity measures, did not support the hypothesis of greater intra- than interracial diversity, which suggests that ethnic variation can be conservatively estimated by racial variation.

Cluster Analysis↗
PubMed1992

Delayed compliance increase in infants with respiratory distress syndrome following synthetic surfactant.

Recent research has demonstrated that Exosurf (EXSF), a newly synthesized artificial surfactant, increases survival when administered endotracheally to premature infants with RDS. This study examines the effects of EXSF on static respiratory system compliance (Crs). Thirty-four patients received two doses of EXSF in this rescue protocol. Crs (mL/cmH2O/kg) did not significantly change within the first 4 hours after either dose. However, Crs values did increase significantly (paired Student's t-test, P = 0.005) when data collected after the second dose (0.36 +/- 0.13 mL/cmH2O/kg) were compared to first week follow-up data (0.51 +/- 0.21 mL/cmH2O/kg). Crs data collected between 2 and 4 weeks after treatments were again not significantly different from non-concurrent control data collected at 3-4 weeks of life. The measurement of Crs in infants receiving EXSF may have been affected by an increase in lung inflation, which could mask an increase in Crs. We speculate that improved lung inflation may occur with less barotrauma in the first week of life due to surfactant replacement treatment and may in part explain the improved Crs seen at 1 week of age. Many investigators using different surfactants, dosing schedules, and pulmonary function methodologies to evaluate lung mechanics have reported that the improvement in compliance after surfactant treatment usually follows the clinical improvement in gas exchange. Additional studies are needed to explain the mechanism of early improvement following surfactant replacement in infants with RDS.

Drug Combinations↗
PubMed1991

SPECT imaging of the benzodiazepine receptor in non-human primate brain with [123I]Ro 16-0154.

We have used SPECT (single photon emission computed tomography) imaging in non-human primates to examine the time course and pharmacological specificity of 123I-labeled Ro 16-0154 as an in vivo probe of the benzodiazepine receptor. Maximal brain uptake was reached approximately 70 min post i.v. administration of the radioligand and represented approximately 10% of the injected dose. The regional distribution of radioactive densities was consistent with the known distribution of benzodiazepine receptors in primate brain, with highest uptake localized over the occipital area. Washout of radioactivity was relatively slow with a rate of 3% per hour after the time of peak radioactivity. Injection of the benzodiazepine antagonist Ro 15-1788 (0.2-0.3 mg/kg i.v.) caused a rapid decrease of more than 90% of radioactivity from brain. In summary, [123I]Ro 16-0154 is a promising in vivo SPECT radioligand for the benzodiazepine receptor, with high brain uptake, a stable period of peak radioactivity, appropriate regional distribution, and ability to be displaced by other benzodiazepine receptor agents.

Animals↗
PubMed1988

Nocturnal asthma: snoring, small pharynx and nasal CPAP.

We studied two populations of patients who snored and had frequent nocturnal asthma attacks: ten overweight men presenting with typical obstructive sleep apnoea syndrome, and a group of five adolescents with regular snoring and an increase in negative inspiratory oesophageal pressure during stage II non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. All subjects presented cranio-mandibular abnormalities at cephalometric evaluation, with a narrow space behind the base of the tongue. Both populations were treated with nasal continuous positive airway pressure (CPAP) during sleep. Snoring and partial or complete airway obstruction were eliminated, as were the nocturnal asthma attacks. Two adolescents treated with upper airway surgery after nasal CPAP showed no nocturnal asthma at short-term follow-up. Nasal CPAP had no effect on daytime asthma. One hypothesis is that a subgroup of asthmatic patients with small pharynxes may have enhanced vagal stimulation during sleep compared with other asthmatic patients. This enhancement would be related to the repetitive Müller manoeuvres noted with airway obstruction during sleep. Combined with the local effects of snoring, this extra vagal stimulation would be a precipitating factor in nocturnal asthma attacks.

Adolescent↗
PubMed1986

Alternative treatment to tracheostomy in obstructive sleep apnea syndrome: nasal continuous positive airway pressure in young children.

Two groups of prepubertal children with severe obstructive sleep apnea syndrome received continuous positive airway pressure (CPAP) treatment using a nasal mask. The five children in group A had nasal CPAP only in a hospital setting; the five children in group B received the treatment at home as well. Four of these five children, who have now been followed for as long as 10 months, have adapted well to the treatment at home. The problems encountered with nasal CPAP as a home treatment, such as poor cooperation from parents, allergic rashes, eye irritation resulting from air leaks, are discussed. Despite the problems, nasal CPAP is a valid alternative to tracheostomy in children as young as 3 years of age.

Child↗
PubMed1986

Portasystemic shunt fraction quantification with colonic iodine-123 iodoamphetamine.

Portasystemic shunting was quantified in dogs with [123I]iodoamphetamine (IMP) administered transrectally into the colon and monitored externally with a gamma camera. IMP was absorbed rapidly and unchanged from the colon. After direct injection into the portal vein, IMP was almost completely extracted by the liver on the first pass, and the washout half-life was approximately 60 min. Based on these kinetic data, computer simulation of this biologic system was carried out. Errors associated with simplified models are calculated. The simplest model with insignificant error, which assumed that the tracer behaved like microspheres, was used to quantitate portasystemic shunt fraction in animals with surgically created shunts. Results were compared with the standard of 99mTc-labeled macroaggregated albumin infused into a branch of inferior mesenteric vein. For shunt fractions ranging from 0 to 100%, an excellent correlation was seen, indicating that this approach is potentially a simple, noninvasive method of portasystemic shunt fraction quantification.

Amphetamines↗
PubMed1985

Near-miss sudden infant death syndrome in eight infants with sleep apnea-related cardiac arrhythmias.

Eight full-term infants between 3 and 8 weeks of age, who had had 24 to 48 hours of vague problems involving a congested upper airway and/or irritability, had a life-threatening respiratory episode at home, called a near-miss for sudden infant death syndrome event. Polygraphically monitored mixed apneas occurred in clusters during non-rapid eye movement (NREM) sleep with significant cardiac arrhythmias, predominantly sinus arrest. The cardiorespiratory problems continued during sleep in the following 8 to 12 weeks but did not recur after that time, and there were no long-term sequelae when the children were studied again 4 to 7 years later.

Arrhythmias, Cardiac↗
PubMed1984

Evaluation of professional nursing practices in a community hospital cancer program: the methodology.

In summary, this evaluation plan is designed to assess current oncology nursing practices in a community setting. The focus of the plan is on patient problems identified in the CHCP Cancer Nursing Guidelines and the Hospice Nursing Guidelines. Critical decisions regarding which patient problems to focus on and the implementation of the evaluation plan remain with the CHCP committees. Technical assistance is provided by a CHCP Evaluation Specialist. Finally, summary reports will be generated at regular intervals so as to maximize the impact on current program development. There are several implications for this nursing evaluation plan, both immediate and long range. In the immediate, we hope that the results will help CHCP committees and individual hospitals make informed decisions about future program development. More importantly perhaps, we are for the first time in our local community identifying services central to nursing and developing base line data on the frequency of the delivery of these services. Looking into the future, we see additional implications for these studies. Currently, our evaluation system is a paper system, and paper systems are by their very nature time consuming and somewhat awkward. It is our hope that in the future information about nursing services will be registered on a computerized information system. Then, reports about the types of nursing services and amount of time spend with cancer patients could be automatically generated on a weekly basis, if so desired. However, if we are to attain this goal, we need to systematically identify common patient problems central to oncology nursing care that can be documented and studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Hospitals, Community↗
PubMed1983

'Near-miss' for sudden infant death syndrome infants: a clinical problem.

Three hundred six infants were referred for evaluation of "near-miss" sudden infant death syndrome (SIDS) from 1973 to 1980. Following the hospitalization and medical evaluation, there were 156 infants (115 term and 41 preterm) for whom there was no explanation for the presenting event and who were considered near-miss infants; 88% of these infants were seen during the first 3 months of life. A repeat near-miss event was reported in 63% (term) and 83% (preterm) infants. Twelve percent of term infants and 17% of the preterm infants had ten or more repeat events. A home apnea/cardiac monitor was prescribed for 88% of the infants for an average duration of 5.6 months in term infants and 3.5 months in preterm infants. Monitoring had been discontinued in 69% of the infants by 7 months of age. One full-term infant was later a SIDS victim. The risk of a repeat near-miss event is concluded to be sufficiently great to demand immediate hospitalization, medical evaluation, home monitoring when there is no specific treatment, and close clinical follow-up. Follow-up studies are needed to determine whether there is any long-term morbidity for infants who have had near miss events.

Age Factors↗