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Biomedical subjects

R A Hamilton

Publications and source records attributed to R A Hamilton.

At least 19 recordsLinked to original sources
PubMed2001

Cholesterol and glycemic effects of Niaspan in patients with type 2 diabetes.

STUDY OBJECTIVE: To determine the effect of Niaspan--a niacin preparation with both immediate- and extended-release characteristics--on lipid and glycemic control in patients with type 2 diabetes. DESIGN: Retrospective study SETTING: Private-practice endocrinology group. PATIENTS: Thirty-two patients (mean age 60 yrs; 72% men) with type 2 diabetes identified by a computerized text search. INTERVENTION: Patients received Niaspan 1000, 1500, or 2000 mg/day (median daily dosage 1000 mg). MEASUREMENTS AND MAIN RESULTS: Total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, hemoglobin A1c, and transaminase levels were compared for each patient before and 6 months after initiation of Niaspan. Niaspan therapy was associated with a significant 34% increase in HDL (p=0.033), a significant 36% reduction of triglycerides (p=0.049), and no significant change in LDL (p=0.236) or total cholesterol (p=0.122). Mean hemoglobin A1c levels significantly decreased from baseline by 0.5 +/- 0.3% (p=0.032), even though dosages and treatment with antidiabetic agents remained constant. There were no significant changes in transaminase levels. Seven patients (21.9%) discontinued Niaspan; one of them experienced an increase in blood glucose while receiving the agent. CONCLUSION: For most patients with type 2 diabetes, Niaspan is a safe and effective therapy for dyslipidemia and does not exacerbate glycemic control.

Blood Glucose↗
PubMed2000

Home care pharmacy: extending clinical pharmacy services beyond infusion therapy.

A clinical pharmacy program was developed at an established home health care (HHC) agency to demonstrate the need for clinical pharmacy services in the HHC population and to explore opportunities for providing pharmaceutical care beyond infusion-related therapies. Initial experiences of this pilot project are described. Patients were found to be primarily elderly (mean age, 70 years) and to use a substantial number of medications. While only 11% of patients referred to the agency required infusion therapy, multiple opportunities for pharmacist involvement in patient care were identified and a variety of projects were undertaken. A drug information service was developed, a retrospective evaluation of patients with congestive heart failure led to an interventional study, a cisapride intervention was implemented, home vancomycin monitoring was assessed, pharmaceutical care services were provided to patients enrolled in a long-term home care program, a pain management initiative was begun, adverse drug reactions were identified and reported, and pharmacists participated in agency policy development. Preliminary data suggest that pharmacist involvement positively affected patient care. Drug information was provided on 232 occasions. Cisapride was discontinued in five patients with contraindications to the agent. Comprehensive pharmacotherapy assessments were performed on 29 long-term-care patients, generating 129 therapy recommendations of which 33% were accepted. Pharmacists working with a home care agency identified numerous opportunities for improving patient care. Many of the patients receiving home care services were elderly, took a substantial number of medications, and were at risk for drug-related problems and suboptimal therapy.

Aged↗
PubMed2000

Determination of seasonality in southern hairy-nosed wombats (Lasiorhinus latifrons) by analysis of fecal androgens.

Little is known about the reproductive biology of Australia's critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii), largely due to its cryptic nature and the difficulty in accessing the small remaining population of about 70 animals. Using the noninvasive technique of fecal steroid analysis, we have examined the endocrinology of the more common yet closely related southern hairy-nosed wombat (Lasiorhinus latifrons). The aims of this study were to 1) develop and validate fecal androgen analysis in this species, 2) examine and compare seasonal differences in fecal and plasma androgens in male wombats, and 3) correlate seasonal differences in androgens with changes in male accessory glands (prostate and bulbourethral gland). Fecal androgens were extracted in ether; concentrated; separated by HPLC into testosterone (T), dihydrotestosterone (DHT), and 5 alpha-androstane-3 alpha,17 beta-diol (Adiol) fractions; and quantitated by RIA. The concentrations of androgens in fecal pellets from 14 wild southern hairy-nosed wombats as determined by RIA varied over the range 6.6-25.0 ng/g dry weight for T, 4.0-24.2 ng/g dry weight for DHT, and 0-34.8 ng/g dry weight for Adiol. For each androgen, a highly significant linear correlation was observed between plasma and fecal concentrations. When individuals were grouped into either breeding season (pellets collected between August-November) or nonbreeding season (collected between February-April), significant (P < 0.05) differences between seasons were observed for both plasma and fecal T, plasma DHT, and fecal Adiol. For all androgens, the mean fecal and plasma concentrations were higher during the breeding season than the nonbreeding season. A significant (P < 0.001) correlation was observed between fecal T and prostate weight, while DHT and Adiol correlations were nonsignificant. Significant correlations were observed, however, between all three fecal androgens and bulbourethral gland weight. These studies demonstrate that fecal T is a valid indicator of reproductive status in the male southern hairy-nosed wombat, with significant correlations observed between fecal T, plasma T, and prostate and bulbourethral gland weights. These findings have important implications for the study of the reproductive endocrinology of the critically endangered northern hairy-nosed wombat.

Androgens↗
PubMed1997

Why intramuscular methotrexate may be more efficacious than oral dosing in patients with rheumatoid arthritis.

In order to compare the relative bioavailability of orally administered methotrexate (MTX) with i.m. administration in patients with rheumatoid arthritis, we compared the pharmacokinetics of MTX at both the usual starting dose of 7.5 mg and at higher established maintenance dosages in 21 patients. Pharmacokinetic measures were repeated approximately 6 and 18 months after baseline while patients consumed their usual maintenance doses of MTX (17.0 +/- 3.8 mg). The relative bioavailability of the usual maintenance dose of MTX was reduced by 13.5% compared with the initial dose of 7.5 mg (P = 0.026). Area under the serum concentration vs time curve (AUC) was significantly reduced with oral vs i.m. administration at usual maintenance doses (decrease of 0.729 mumol.h/l by oral administration, P = 0.027), but not at a 7.5 mg dose of MTX. Clinicians using MTX should not assume constant and complete bioavailability across the dose range used to treat patients with rheumatoid arthritis. Our observations explain the reported clinical success of switching from an oral to a parenteral route of administration in patients receiving maintenance doses of MTX.

Administration, Oral↗
PubMed1996

Enhanced myocardial relaxation in vivo in transgenic mice overexpressing the beta2-adrenergic receptor is associated with reduced phospholamban protein.

To assess the effect of targeted myocardial beta-adrenergic receptor (AR) stimulation on relaxation and phospholamban regulation, we studied the physiological and biochemical alterations associated with overexpression of the human beta2-AR gene in transgenic mice. These mice have an approximately 200-fold increase in beta-AR density and a 2-fold increase in basal adenylyl cyclase activity relative to negative littermate controls. Mice were catheterized with a high fidelity micromanometer and hemodynamic recordings were obtained in vivo. Overexpression of the beta2-AR altered parameters of relaxation. At baseline, LV dP/dt(min) and the time constant of LV pressure isovolumic decay (Tau) in the transgenic mice were significantly shorter compared with controls, indicating markedly enhanced myocardial relaxation. Isoproterenol stimulation resulted in shortening of relaxation velocity in control mice but not in the transgenic mice, indicating maximal relaxation in these animals. Immunoblotting analysis revealed a selective decrease in the amount of phospholamban protein, without a significant change in the content for either sarcoplasmic reticulum Ca2+ ATPase or calsequestrin, in the transgenic hearts compared with controls. This study indicates that myocardial relaxation is both markedly enhanced and maximal in these mice and that conditions associated with chronic beta-AR stimulation can result in a selective reduction of phospholamban protein.

Animals↗
PubMed1996

Monitoring for undertransfusion.

BACKGROUND: Most published reviews and audits of blood and blood component transfusion have focused on the issue of overtransfusion and on the inappropriate use of red cell components. There is growing concern that efforts to curb unnecessary transfusions may result in a trend toward undertransfusion of patients. There is little published information that addresses this issue or the magnitude of this practice. STUDY DESIGN AND METHODS: Undertransfusion was evaluated by examining the transfusion records from a 3-month period for 55 patients who met the study criteria of having either a hemoglobin level < 7 g per dL or a platelet count of < 10 x 10(9) per L. If the identified patient did not receive a transfusion within 24 hours of the reported hemoglobin level or platelet count, the medical record was reviewed by a resident physician. RESULTS: A total of 213 individual hemoglobin levels and platelet counts, representing the 55 patients, met our transfusion criteria. All except 8 of the identified patients received red cells and/or platelet transfusions. Reasons for not transfusing red cells included the patient's response to nutritional support and iron supplementation, refusal of blood, and noncompliance. Reasons for not transfusing platelets included falsely low platelet count because of platelet clumping in vitro, contraindication based on clinical diagnosis (e.g., immune thrombocytopenic purpura), and the patient's death before transfusion. CONCLUSION: Red cell and platelet transfusions were appropriately ordered for all patients who met the transfusion criteria. Undertransfusion is not a problem at this institution according to the criteria established. It is recommended that other institutions expand their blood utilization audits to include investigation for evidence of undertransfusion. Further research regarding the issue of undertransfusion is warranted and could be expanded to include other components.

Alcoholism↗
PubMed1995

Cardiac function in mice overexpressing the beta-adrenergic receptor kinase or a beta ARK inhibitor.

Transgenic mice were created with cardiac-specific overexpression of the beta-adrenergic receptor kinase-1 (beta ARK1) or a beta ARK inhibitor. Animals overexpressing beta ARK1 demonstrated attenuation of isoproterenol-stimulated left ventricular contractility in vivo, dampening of myocardial adenylyl cyclase activity, and reduced functional coupling of beta-adrenergic receptors. Conversely, mice expressing the beta ARK inhibitor displayed enhanced cardiac contractility in vivo with or without isoproterenol. These animals demonstrate the important role of beta ARK in modulating in vivo myocardial function. Because increased amounts of beta ARK1 and diminished cardiac beta-adrenergic responsiveness characterize heart failure, these animals may provide experimental models to study the role of beta ARK in heart disease.

Adenylyl Cyclases↗
PubMed1995

Pharmacokinetics and renal function in patients with rheumatoid arthritis receiving a standard dose of oral weekly methotrexate: association with significant decreases in creatinine clearance and renal clearance of the drug after 6 months of therapy.

OBJECTIVE: To determine the pharmacokinetics of a standard oral dose of 7.5 mg in a cohort of patients beginning methotrexate (MTX) and continuing the drug over 24 months. METHODS: Twenty-one patients underwent pharmacokinetic testing after receiving a dose of 7.5 mg of oral MTX and concomitant nonsteroidal antiinflammatory drug (NSAID) therapy. Studies were performed at the time of MTX initiation, and after 6 and 24 months of therapy. RESULTS: No significant differences with time were observed in area under the serum concentration versus time curve (AUC), maximal MTX concentration achieved postdosing (Cmax) or time to maximal MTX concentration (Tmax). Renal clearance of MTX at 6 months decreased by a mean (+/- SD) of 23.8 (40.3) cc/min (p = 0.014). Creatinine clearance decreased by 8.6 cc/min (17.2) (p = 0.033) at 6 months. CONCLUSION: No differences in AUC, Tmax, or Cmax were observed over a 2 year period in patients with rheumatoid arthritis on a standard 7.5 mg dose of MTX. Renal clearance and creatinine clearance both decreased significantly after 6 months of treatment. This effect may be clinically relevant in certain individuals as MTX is renally excreted.

Aged↗
PubMed1995

Examination of pharmacokinetic variables in a cohort of patients with rheumatoid arthritis beginning therapy with methotrexate compared with a cohort receiving the drug for a mean of 81 months.

OBJECTIVE: To compare pharmacokinetic variables of a 7.5 mg dose of MTX in a cohort of patients with rheumatoid arthritis (RA) beginning therapy with the drug with a cohort of patients receiving the drug for a mean period of 81 months. METHODS: Standard pharmacokinetic measures were performed in 35 patients beginning MTX therapy and 15 patients who had received the drug for a mean of 81 months. RESULTS: No significant differences in area under the serum concentration versus time curve (AUC), maximal methotrexate concentration following dosing (Cmax), time to Cmax (Tmax), bioavailability (F), urinary MTX, renal clearance of MTX or creatinine clearance were observed between the 2 cohorts. CONCLUSION: We were unable to demonstrate significant differences in pharmacokinetic variables in these cohorts with a 7.5 mg standard dose of MTX. It is possible that a difference may exist when a standard higher dose of MTX is compared in these types of patients.

Administration, Oral↗
PubMed1995

The effects of food on methotrexate absorption.

OBJECTIVE: To determine the effects of food on methotrexate (MTX) absorption in patients receiving MTX for the treatment of rheumatoid arthritis (RA). METHODS: Standard pharmacokinetic variables were determined in patients with RA after their usual maintenance dose of MTX, under fasting conditions and after they ate a standard breakfast. RESULTS: No significant differences in area under the serum concentration versus time curve, maximal MTX concentration after dosing (Cmax), time to Cmax), bioavailability, urinary MTX, renal clearance of MTX, or creatinine clearance were observed between the 2 dosing conditions. CONCLUSION: We observed no significant effect of food on MTX absorption or bioavailability. Patients may consume MTX without regard to meals.

Absorption↗
PubMed1995

The effects of nonsteroidal antiinflammatory drugs on methotrexate (MTX) pharmacokinetics: impairment of renal clearance of MTX at weekly maintenance doses but not at 7.5 mg.

OBJECTIVE: To determine the pharmacokinetics of methotrexate (MTX) with and without nonsteroidal antiinflammatory drugs (NSAID) at a 7.5 mg dose and higher usual maintenance doses of the drug. To determine the difference in pharmacokinetic variables when salicylate and nonsalicylate NSAID are administered with MTX at these doses. METHODS: Thirty patients receiving MTX chronically underwent a study of MTX pharmacokinetics after 7.5 mg doses of MTX with their usual NSAID and after the NSAID were withheld for 5 half-lives. Sixteen additional patients underwent pharmacokinetics studies with and without NSAID while receiving their usual weekly maintenance dose of MTX of 16.6 (3.6) mg (Mean +/- SD). RESULTS: No significant differences in pharmacokinetic variables were observed with and without NSAID at the 7.5 mg weekly dose of MTX. When patients received usual maintenance doses of MTX the renal clearance of MTX NSAID was 91.7 (26.4) ml/min versus 115.3 (34.4) ml/min without NSAID (p = 0.004). Creatinine clearance in patients taking usual maintenance doses increased from 77.5 (13.9) ml/min with NSAID to 95.3 (26.3) ml/min without NSAID (p = 0.05). A reduction in renal clearance of MTX was observed with maintenance dose MTX in both the 4 patients taking salicylates (p = 0.016) and the 12 patients taking nonsalicylate NSAID (p = 0.024). CONCLUSION: NSAID produce significant decreases in renal clearance of MTX and creatinine when patients consume their usual weekly dose of the drug, but not when they take a 7.5 mg dose. This effect is likely to achieve clinical relevance across the dose ranges used to treat patients with rheumatoid arthritis.

Aged↗
PubMed1994

Marketing to rural seniors: opportunities for the service sector.

A recent study of rural Midwestern elderly consumers revealed a need for and interest in purchasing services designed for this sizeable and rapidly growing market. The study investigated the levels of need for 54 proposed services which could be provided through non-governmental institutions (businesses and non-profit organizations), along with the elderly consumer's ability and willingness to pay a "reasonable price" for the services. Based on the research findings, those service categories possessing market potential are presented and recommendations for marketing to rural elderly consumers are discussed.

Aged↗
PubMed1992

Incidence and cost of hospital admissions secondary to drug interactions involving theophylline.

OBJECTIVE: To determine the incidence and cost of hospital admissions for theophylline toxicity, which occurred as a result of the concurrent use of one of the following medications: cimetidine, erythromycin, or ciprofloxacin. DESIGN: Retrospective chart review (18 months, between June 1989 and November 1990). SETTING: A Department of Veterans Affairs Medical Center. PARTICIPANTS: All patients who were receiving theophylline chronically (913 patients) and also had a prescription for cimetidine (124 patients with 140 treatment courses), erythromycin (66 patients with 93 treatment courses), or ciprofloxacin (39 patients with 59 treatment courses) dispensed. INTERVENTIONS: Each patient's medical record was reviewed to identify hospital admissions within 30 days following the dispensing of the interacting drug. MAIN OUTCOME MEASURES: Admissions were considered to be related to theophylline toxicity if appropriate signs and symptoms were present and the theophylline concentration was above 20 micrograms/mL or had increased significantly from the concentration obtained prior to introduction of the interacting drug. RESULTS: One patient who received cimetidine and one who received ciprofloxacin were admitted for theophylline toxicity (2 of 292 potential interactions, 0.81 percent). Admissions were for 16 and 13 days, respectively, and total costs for the two admissions were $12,864.22 or $44.00, respectively, per potential interaction. The entire admission was not for theophylline toxicity; it appeared that iatrogenic factors contributed to the duration. CONCLUSIONS: The incidence of hospital admissions secondary to theophylline drug interactions with cimetidine, ciprofloxacin, or erythromycin is low, but the admissions represent considerable expense, even when distributed among all patients at risk for the interactions.

Aged↗
PubMed1992

Neural tube defects--prenatal diagnosis and management.

Neural tube defects rank second to congenital heart disease as a major cause of congenital malformation. Recent developments in ultrasound have improved prenatal diagnosis. Due to anomaly scans at 18 weeks gestation and the availability of a genetic clinic, prenatal diagnosis of neural tube defects at the Royal Maternity Hospital was 91.2% during 1987-1989. However, only 50% of parents accept termination of pregnancy and it is questionable if prenatal diagnosis is of benefit to those who wish to continue with the pregnancy. Parents may accept the situation better at birth, having had time to come to terms with it, helped with support from the obstetrician, clinical geneticist, paediatrician, genetic nurse and social worker. For some affected fetuses who have better muscle function and leg movement at term it appears from the literature that the outcome may be improved by caesarean section delivery. In Ireland fetuses with neural tube defects will continue to be delivered, as termination is unacceptable to many, but despite this there may be a positive benefit from prenatal diagnosis of neural tube defects. Prospective randomised controlled trials are needed to confirm benefit from delivery by caesarean section for fetuses with a good prognosis. As a result of prenatal diagnosis of a neural tube lesion the fetus should enjoy benefit in terms of physical morbidity, and the parents should benefit in terms of psychological morbidity.

Abortion, Induced↗