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Biomedical subjects

R Friedman

Publications and source records attributed to R Friedman.

At least 37 records · Page 2Linked to original sources
PubMed1999

Intravascular extraction of problematic or infected permanent pacemaker leads: 1994-1996. U.S. Extraction Database, MED Institute.

Of the 400,000-500,000 permanent pacemaker leads implanted worldwide each year, around 10% may eventually fail or become infected, becoming potential candidates for removal. Intravascular techniques for removing problematic or infected leads evolved over a 5-year period (1989-1993). This article analyzes results from January 1994 through April 1996, a period during which techniques were fairly stable. Extraction of 3,540 leads from 2,338 patients was attempted at 226 centers. Indications were: infection (27%), nonfunctional or incompatible leads (25%), Accufix or Encore leads (46%), or other causes (2%). Patients were 64+/-17 years of age (range 5-96); 59% were men, 41% women. Leads were implanted 47+/-41 months (maximum 26 years), in the atrium (53%), ventricle (46%), or SVC (1%). Extraction was attempted via the implant vein using locking stylets and dilator sheaths, and/or transfemorally using snares, retrieval baskets, and sheaths. Complete removal was achieved for 93% of leads, partial for 5%, and 2% were not removed. Risk of incomplete or failed extraction increased with implant duration (P<0.0001), less experienced physicians (P<0.0001), ventricular leads (P<0.005), noninfected patients (P<0.0005), and younger patients (P<0.0001). Major complications were reported for 1.4% of patients (<1% at centers with >300 cases), minor for 1.7%. Risk of complications increased with number of leads removed (P<0.005) and with less experienced physicians (P<0.005); risk of major complications was higher for women (P<0.01). Given physician experience, appropriate precautions, and appropriate patient selection, contemporary lead removal techniques allow success with low complication rates.

Adolescent↗
PubMed1999

Distress and conception in infertile women: a complementary approach.

OBJECTIVES: To examine the relationship of pretreatment psychological distress and demographics to conception in infertile women attending a group cognitive-behavioral treatment program. METHODS: Pre- and postprogram psychological measures and live birth rates were collected for 132 infertile women attending a ten-session group cognitive-behavioral treatment program. Subjects completed the Beck Depression Inventory (BDI) and the Symptom Checklist-90 (Revised) (SCL-90R). Conceptions that resulted in live births within six months of completing the program were noted. RESULTS: Women who conceived viable pregnancies within six months of the program had higher levels of psychological distress at program entry. Using logistic regression analysis, the best predictors of viable birth were younger age and a higher score on the global severity index of the SCL-90R. Significant pre- to postprogram psychological improvement was demonstrated by the SCL-90R and the BDI. Forty-two percent of the sample conceived viable pregnancies within six months of completing the program. CONCLUSIONS: Preprogram psychological distress and younger age were associated with significantly higher viable pregnancy rates.

Adult↗
PubMed1998

Effects of therapy with nifedipine GITS or atenolol on mental stress-induced ischemic left ventricular dysfunction.

OBJECTIVES: We sought to determine the effect of nifedipine gastrointestinal therapeutic system (GITS) or atenolol on ischemic left ventricular dysfunction induced by mental stress. BACKGROUND: The efficacy of conventional antianginal therapy in preventing myocardial ischemia induced by mental stress is unknown. METHODS: Nifedipine GITS, atenolol and placebo were administered to 15 subjects with stable angina in a double-blind crossover trial. Subjects underwent a series of mental stressors at the end of each treatment. Radionuclide ventriculography was performed at baseline and at peak mental stress. Other measured variables included time to ischemia on exercise treadmill testing, ischemia on 48-h ambulatory electrocardiogram (ECG) monitoring, and resting and mental stress-induced levels of plasma catecholamines, tissue plasminogen activator antigen, plasminogen activator inhibitor-1 and platelet aggregability. RESULTS: Mental stress resulted in a significant increase in plasma epinephrine and norepinephrine levels during each treatment phase. Atenolol therapy was associated with lower baseline and postmental stress rate-pressure product compared with nifedipine or placebo. Therapy with either nifedipine GITS or atenolol prevented the development of wall-motion abnormalities and the decline in regional ejection fraction (EF) in the segment with the largest deterioration in wall motion during placebo therapy. Both medications prevented the decrease in global EF in subjects who demonstrated at least a 5% fall in global EF on placebo therapy. No therapy exerted a statistically significant benefit on exercise performance or frequency of ischemia during ambulatory ECG monitoring. CONCLUSIONS: Both nifedipine GITS and atenolol are effective at preventing mental stress-induced wall-motion abnormalities, although the mechanisms may be different.

Adrenergic beta-Antagonists↗
PubMed1998

Comparison of long-term care in an acute care institution and in a long-term care institution.

BACKGROUND: Acute care hospitals in Quebec are required to reserve 10% of their beds for patients receiving long-term care while awaiting transfer to a long-term care facility. It is widely believed that this is inefficient because it is more costly to provide long-term care in an acute care hospital than in one dedicated to long-term care. The purpose of this study was to compare the quality and cost of long-term care in an acute care hospital and in a long-term care facility. METHODS: A concurrent cross-sectional study was conducted of 101 patients at the acute care hospital and 102 patients at the long-term care hospital. The 2 groups were closely matched in terms of age, sex, nursing care requirements and major diagnoses. Several indicators were used to assess the quality of care: the number of medical specialist consultations, drugs, biochemical tests and radiographic examinations; the number of adverse events (reportable incidents, nosocomial infections and pressure ulcers); and anthropometric and biochemical indicators of nutritional status. Costs were determined for nursing personnel, drugs and biochemical tests. A longitudinal study was conducted of 45 patients who had been receiving long-term care at the acute care hospital for at least 5 months and were then transferred to the long-term care facility where they remained for at least 6 months. For each patient, the number of adverse events, the number of medical specialist consultations and the changes in activities of daily living status were assessed at the 2 institutions. RESULTS: In the concurrent study, no differences in the number of adverse events were observed; however, patients at the acute care hospital received more drugs (5.9 v. 4.7 for each patient, p < 0.01) and underwent more tests (299 v. 79 laboratory units/year for each patient, p < 0.001) and radiographic examinations (64 v. 46 per 1000 patient-weeks, p < 0.05). At both institutions, 36% of the patients showed anthropometric and biochemical evidence of protein-calorie undernutrition; 28% at the acute care hospital and 27% at the long-term care hospital had low serum iron and low transferrin saturation, compatible with iron deficiency. The longitudinal study showed that there were more consultations (61 v. 37 per 1000 patient-weeks, p < 0.02) and fewer pressure ulcers (18 v. 34 per 1000 patient-weeks, p < 0.05) at the acute care hospital than at the long-term care facility; other measures did not differ. The cost per patient-year was $7580 higher at the acute care hospital, attributable to the higher cost of drugs ($42), the greater use of laboratory tests ($189) and, primarily, the higher cost of nursing ($7349). For patients requiring 3.00 nursing hours/day, the acute care hospital provided more hours than the long-term care facility (3.59 v. 3.03 hours), with a higher percentage of hours from professional nurses rather than auxiliary nurses or nursing aides (62% v. 28%). The nurse staffing pattern at the acute care hospital was characteristic of university-affiliated acute care hospitals. INTERPRETATION: The long-term care provided in the acute care hospital involved a more interventionist medical approach and greater use of professional nurses (at a significantly higher cost) but without any overall difference in the quality of care.

Aged↗
PubMed1998

Accuracy of conversion formulae for estimation of glycohaemoglobin.

To analyse the accuracy of the conversion formulae for estimation of glycohaemoglobin (GHb) measured by different methods, we analysed 210 samples for HbA1c using HPLC. Fifty of these specimens were analysed by micro-column chromatography (MC), 43 by electrophoresis (EP), 50 by IMX system (Abbott Laboratories), 38 by Primus HPLC and 29 by Diamat HPLC. Regression analyses were performed and the equations were used to estimate HbA1c values (HbA1c calc) for the five methods. The 95% limits of agreement between HPLC and the converted results were -1.77 to 1.71%, -1.54 to 1.54%, -0.92 to 0.88%, -0.46 to 0.56%, and -0.39 to 0.41% for MC, EP, IMX, Primus and Diamat equations, respectively. The mean relative errors were 3.4 (-28.2 to 35%), 1.3 (-22.9 to 25.5%), 0.4 (-14.6 to 15.0%), 0.51 (-6.55 to 7.57%), -0.20 (-5.8 to 5.4%), for MC, EP, IMX, Primus and Diamat, respectively. These results show that conversion formulae based on methods that do not measure HbA1c (MC, EP and IMX) are inaccurate and can mask a clinically relevant variation of HbA1c. However, GHb results obtained by HPLC methods could be interchangeably converted with an absolute variation of less than 1%. Converted HbA1c results from non-standardized methods should be interpreted with caution.

Chromatography, Affinity↗
PubMed1998

Profiling outcomes of ambulatory care: casemix affects perceived performance.

OBJECTIVES: The authors explored the role of casemix adjustment when profiling outcomes of ambulatory care. METHODS: The authors reviewed the medical records of 656 patients with hypertension, diabetes, or chronic obstructive pulmonary disease (COPD) receiving care at one of three Department of Veterans Affairs medical centers. Outcomes included measures of physiological control for hypertension and diabetes, and of exacerbations for COPD. Predictors of poor outcomes, including physical examination findings, symptoms, and comorbidities, were identified and entered into regression models. Observed minus expected performance was described for each site, both before and after casemix adjustment. RESULTS: Risk-adjustment models were developed that were clinically plausible and had good performance properties. Differences existed among the three sites in the severity of the patients being cared for. For example, the percentage of patients expected to have poor blood pressure control were 35% at site 1, 37% at site 2, and 44% at site 3 (P < 0.01). Casemix-adjusted measures of performance were different from unadjusted measures. Sites that were outliers (P < 0.05) with one approach had observed performance no different from expected with another approach. CONCLUSIONS: Casemix adjustment models can be developed for outpatient medical conditions. Sites differ in the severity of patients they treat, and adjusting for these differences can alter judgments of site performance. Casemix adjustment is necessary when profiling outpatient medical conditions.

Aged↗
PubMed1998

Problems in assessing diabetes control in an ambulatory setting.

Problems in using medical records to assess outcomes of diabetes care have not been well defined. We reviewed the medical records of 288 patients with diabetes receiving ambulatory care over a 2-year period. We determined the availability of different tests of glycemic control and described site performance as the percentage of patients with a blood glucose exceeding either 180 or 240 mg/dl. Glycosylated hemoglobin determinations were performed in only 26.7% of patients. A blood glucose was available in 208 patients (72.2%) during a 6-month outcome period. For almost 50% of the sample, the glucose was greater than 180 mg/dl, whereas in 20% it exceeded 240 mg/dl. Judgments of whether sites differed in performance depended on how control was defined. Using a single glucose determination and a threshold of 180 mg/dl, similar fractions of patients were poorly controlled at each site (51.2 versus 45.0 versus 47.0%) (P = 0.75). At 240 mg/dl, although, one site performed much worse than the other two (14.6 versus 16.7 versus 31.8%) (P = 0.02). These results highlight difficulties in defining the outcome measure when using medical records to evaluate quality of care.

Aged↗
PubMed1997

Continuous infusion of prostacyclin normalizes plasma markers of endothelial cell injury and platelet aggregation in primary pulmonary hypertension.

BACKGROUND: Primary pulmonary hypertension (PPH) is characterized by vascular injury of pulmonary arterioles, in which endothelial dysfunction may play a major role. Although continuous infusion of prostacyclin (prostaglandin I2, a potent vasodilator released by vascular endothelial cells) improves the clinical status and survival in PPH, its mechanism or mechanisms of action remain unclear. METHODS AND RESULTS: We measured endothelium-derived clotting factors and assayed platelet aggregation in 64 patients (26 adults and 38 children) with PPH before long-term PGI2 therapy. Repeat studies were performed in 42 patients (18 adults, 24 children) after one year of PGI2 therapy. At baseline, 87% of adults and 79% of children had abnormal platelet aggregation. In addition, factor VIII, von Willebrand (vW) antigen, and ristocetin cofactor levels were abnormally high in 92%, 72%, and 52%, respectively, of the adults versus 29%, 16%, and 16%, respectively, of the children (P<.005 adults versus children). With long-term PGI2, platelet aggregation normalized in 83% of the adults and 80% of the children who had platelet aggregation abnormalities at baseline (P<.01). Factor VIII, vW antigen, and ristocetin cofactor also decreased with long-term PGI2 in both groups (P<.02). The ratio of ristocetin cofactor to vW antigen, which may reflect biological activity of vW factor, increased with long-term PGI2 in adults from an abnormally low level (0.6+/-0.2) to normal level (1.10+/-0.4), and in children the ratio increased from 0.8+/-0.3 to 1.3+/-0.4 (normal, 0.8 to 1.4). CONCLUSIONS: Alterations in the coagulation system may contribute to the pathogenesis of PPH; the normalization of these endothelial markers concomitant with improvement in hemodynamic parameters with long-term PGI2 suggests that long-term PGI2 remodels the pulmonary vascular bed with subsequent decreases in endothelial cell injury and hypercoagulability.

Adolescent↗
PubMed1997

Glucocorticoid repression of gonadotropin-releasing hormone gene expression and secretion in morphologically distinct subpopulations of GT1-7 cells.

Two morphologically distinct subpopulations of GT1-7 cells have been characterized and examined for their responsiveness to glucocorticoids. Type I cells have a neuronal phenotype, extending many lengthy processes, and express neuronal, but not glial, markers. Type II cells show weaker or negative immunostaining for neuronal markers and exhibit fewer processes. The effect of glucocorticoids on gonadotropin-releasing hormone (GnRH) secretion and gene expression was compared in type I and type II GT1-7 cells. For secretion studies, cells were attached to Cytodex beads and perifused with control medium or medium containing dexamethasone (dex). The high level of GnRH secreted by type I cells was slightly enhanced in the presence of dex, whereas dex rapidly and profoundly decreased the already low level of GnRH secreted by type II cells. Immunocytochemistry for GnRH showed dark reaction product in the cell bodies and processes of type I cells and little or no immunoreactivity in type II cells. Both the endogenous mouse GnRH mRNA and the transcriptional activity of a mouse GnRH promoter luciferase reporter gene plasmid were suppressed to a greater extent in type II cells than in type I. In electrophoretic mobility shift assays, there was no difference between type I and type II nuclear extracts in the pattern of protein-DNA complexes formed on two previously identified negative glucocorticoid response elements located at -237 to -201 and -184 to -150 bp of the mouse promoter. Both cell types contained glucocorticoid receptors (GR) by Western blot analysis. Cytosols from type I or type II cells were incubated with [3H]dex to obtain GR binding parameters. Binding data were consistent with a one-site model for dex binding in each case. Small differences in Kd (1.7 nM, type I; 3.1 nM, type II) or Bmax (approximately 3600 sites/cell, type I; approximately 1800 sites/cell, type II) were not likely to account for the differential sensitivity to dex treatment. In conclusion, nuclear alterations in type II cells leading to greater transcriptional susceptibility to dex, coupled with low GnRH storage levels, may be reflected in exquisite sensitivity of GnRH secretion to glucocorticoid repression. This represents the first example of a steroid hormone acting directly on GnRH-producing cells to alter GnRH secretion.

Animals↗
PubMed1997

Additional antianginal and anti-ischemic efficacy of mibefradil in patients pretreated with a beta blocker for chronic stable angina pectoris.

This study assessed the safety, tolerability, and efficacy of mibefradil when added to beta-blocker monotherapy in patients with chronic stable angina pectoris. Two hundred five patients were randomized to receive double-blind treatment with either placebo (n = 70), mibefradil 25 mg (n = 67), or mibefradil 50 mg (n = 68) for 2 weeks. Exercise tolerance tests (ETTs) were performed at the end of the run-in (baseline) and double-blind treatment periods, and patients maintained an anginal diary. Compared with placebo, treatment with mibefradil 50 mg resulted in significant increases in exercise duration (36 +/- 51 seconds; p = 0.036), time to onset of angina (48 +/- 65 seconds; p = 0.002), and time to persistent 1-mm ST-segment depression (47 +/- 77 seconds; p = 0.004). Greater reductions in heart rate, blood pressure, and the rate-pressure product were more apparent at each stage of the ETT in the 50-mg mibefradil group than in the placebo group. Daily treatment with mibefradil 50 mg was associated with a significant decrease in the number of weekly anginal attacks (-2.1 +/- 4.0, p = 0.020) compared with placebo. The addition of mibefradil to existing beta-blocker therapy was well tolerated. Dizziness was the most frequently reported adverse event in the mibefradil 50-mg dose, and occurred with an incidence of 4.4%. The addition of mibefradil 50 mg, administered once daily, to patients on stable beta-blocker therapy produced additive antianginal and anti-ischemic effects and was well tolerated.

Adrenergic beta-Antagonists↗
PubMed1997

The dorsal transposition flap for congenital contractures of the first web space: a 20-year experience.

Fifty-four dorsal transposition flaps were performed in 38 patients (46 hands) for severe congenital thumb web-space contractures. At an average follow-up interval of 6 years, complications or unsatisfactory results had occurred in 100% of symbrachydactyly patients and in 27% of all other patients. Postoperative first web-space angle was augmented an average of 59 degrees with a distal flap two-point discrimination of 8 mm. Mean postoperative pinch and grip strengths were 58% and 72%, respectively, of the normal contralateral hand. Parental satisfaction with the functional results was high, and the aesthetic results were generally acceptable. With the exception of symbrachydactyly patients, the dorsal transposition flap remains an excellent reconstructive option for severe congenital contractures of the thumb web space.

Adolescent↗
PubMed1997

Emotional responses to goal attainment: strength of regulatory focus as moderator.

Goals with a promotion focus versus a prevention focus are distinguished. Chronic ideal goals (hopes and aspirations) have a promotion focus, whereas ought goals (duties and responsibilities) have a prevention focus. The hypothesis that emotional responses to goal attainment vary as a function of promotion versus prevention goal strength (conceptualized as goal accessibility) was tested in correlational studies relating chronic goal attainment (self-congruencies or self-discrepancies) to emotional frequency and intensity (Studies 1-3) and in an experimental study relating immediate goal attainment (i.e., success or failure) to emotional intensity (Study 4). All studies found that goal attainment yielded greater cheerfulness-dejection responses when promotion focus was stronger and greater quiescence-agitation responses when prevention focus was stronger.

Affect↗
PubMed1997

Renal functional response to protein loading in type 1 (insulin-dependent) diabetic patients on normal or high salt intake.

Insulin-dependent diabetes mellitus (IDDM) patients may have an increased intrarenal angiotensin II activity. In diabetic patients, captopril increases the renal hemodynamic response to an amino acid infusion. We investigated the effects of two salt diets on arterial pressure and renal response to a protein load in 10 normotensive (blood pressure < 140/90 mm Hg) IDDM patients (aged 30 +/- 3 years) who had diabetes for 7 +/- 4 years and normoalbuminuria levels [albumin excretion rate 4.8 (2.5-19.1) microg/min]. After 1 week of normal (approximately 100 mmol/day; approximately 100 mEq/l) and 1 week of high (approximately 300 mmol/day; approximately 300 mEq/l) salt intake, renal hemodynamic studies were performed at baseline and after a protein load (meat meal) of 100 g/1.73 m2. The mean 24-hour urinary sodium excretion levels were 99 +/- 27 and 293 +/- 80 mmol (mEq) with normal and high salt intake, respectively. No significant changes were seen in plasma sodium and glucose control with the normal and high salt diets, respectively: plasma sodium 135 +/- 3 vs. 137 +/- 1 mmol/l (mEq/l), (p = 0.08) and glycated hemoglobin 9.1 +/- 1.9 vs. 9.4 +/- 2.1% (p = 0.36). The body weight (70.9 +/- 12 vs. 71.8 +/- 13 kg; p = 0.015) was significantly higher with a high salt diet. The mean arterial pressure was similar with both diets (normal vs. high salt diet 91 +/- 9 vs. 89 +/- 6 mm Hg, p = 0.25). The plasma renin concentration [28 +/- 15 vs. 16 +/- 6 microU/ml(168 +/- 90 vs. 96 +/- 36 pmol/l), p = 0.013] and angiotensin II [8.8 +/- 4.4 vs. 6.4 +/- 3.5 pg/ml (0.052 +/- 0.025 vs. 0.038 +/- 0.021 nmol/l), p = 0.016] were significantly lower with the high salt diet. Following protein loading, the glomerular filtration rate increased with both diets: normal salt diet 114 +/- 26 vs. 128 +/- 30 ml/min/1.73 m2(1.9 +/- 0.43 vs. 2.13 +/- 0.50 ml/s/1.73 m2), p = 0.04; high salt diet 118 +/- 23 vs. 127 +/- 29 ml/min/1.73 m2 (1.97 +/- 0.38 vs. 2.12 +/- 0.48 ml/s/1.73 m2), p = 0.13. The change in renal plasma flow was similar to that of the glomerular filtration rate with normal and high salt intake, respectively: 566 +/- 94 vs. 617 +/- 142 ml/min/1.73 m2 (9.44 +/- 1.57 vs. 10.29 +/- 2.37 ml/s/173 m2), p = 0.0017; 572 +/- 125 vs. 600 +/- 110 ml/min/1.73 m2 (9.54 +/- 2.08 vs. 10.00 +/- 1.83 ml/s/1.73 m2), p = 0.057. In this subset of normotensive normoalbuminuric IDDM patients, a high salt intake did not promote an exaggerated renal response to the protein load despite inhibition of the renin-angiotensin system.

Adolescent↗
PubMed1997

TGFbeta2 knockout mice have multiple developmental defects that are non-overlapping with other TGFbeta knockout phenotypes.

The growth and differentiation factor transforming growth factor-beta2 (TGFbeta2) is thought to play important roles in multiple developmental processes. Targeted disruption of the TGFbeta2 gene was undertaken to determine its essential role in vivo. TGFbeta2-null mice exhibit perinatal mortality and a wide range of developmental defects for a single gene disruption. These include cardiac, lung, craniofacial, limb, spinal column, eye, inner ear and urogenital defects. The developmental processes most commonly involved in the affected tissues include epithelial-mesenchymal interactions, cell growth, extracellular matrix production and tissue remodeling. In addition, many affected tissues have neural crest-derived components and simulate neural crest deficiencies. There is no phenotypic overlap with TGFbeta1- and TGFbeta3-null mice indicating numerous non-compensated functions between the TGFbeta isoforms.

Abnormalities, Multiple↗
PubMed1997

Risk factors for decreased bone density in premenopausal women.

Osteoporosis is a major health problem. Little is known about the risk factors in premenopause. Sixty 40-50-year old patients with regular menses were studied cross-sectionally. None of the patients were on drugs known to interfere with bone mass. Patients answered a dietary inquiry and had their bone mineral density (BMD) measured. The Z scores were used for the comparisons. A blood sample was taken for the determination of FSH, SHBG, estradiol, testosterone, calcium and alkaline phosphatase. Calcium and creatinine were measured in 24-h urine. A Z score less than -1 was observed for the lumbar spine of 14 patients (23.3%), and for the femur of 24 patients (40%). Patients with a Z score less than -1 for the lumbar spine were older than patients with a Z score > or = -1 (45.7 vs 43.8 years) and presented higher values of alkaline phosphatase (71.1 +/- 18.2 vs 57.1 +/- 14.3 IU/l). Multiple regression analysis showed that a lower lumbar spine BMD was associated with higher values of alkaline phosphatase, lower calcium ingestion, a smaller body mass index (BMI), less frequent exercising, and older age. The patients with a Z score less than -1 for the femur were shorter than patients with a Z score > or = -1 (158.2 vs 161.3 cm). Multiple regression analysis showed that a lower femoral BMD was associated with lower BMI, higher alkaline phosphatase and caffeine intake, and less frequent exercising. A lower than expected BMD was observed in a significant proportion of premenopausal women and was associated with lower calcium intake, relatively lower physical activity and lower BMI. We conclude that the classical risk factors for osteoporosis may be present before ovarian failure, and their effect may be partly independent of estrogen levels.

Adult↗