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Biomedical subjects

W H Olson

Publications and source records attributed to W H Olson.

At least 19 recordsLinked to original sources
PubMed2005

Effects of an oral contraceptive (norgestimate/ethinyl estradiol) on bone mineral density in women with hypothalamic amenorrhea and osteopenia: an open-label extension of a double-blind, placebo-controlled study.

OBJECTIVE: The effects of long-term triphasic oral contraceptive administration on bone mineral density (BMD) were investigated in premenopausal women with hypothalamic amenorrhea (HA) and osteopenia. METHODS: After completing three 28-day cycles in the double-blind phase of a placebo-controlled trial, women (mean age, 26.7 years) who received norgestimate 180-250 microg/ethinyl estradiol 35 microg (NGM/EE, n = 15) or placebo (n = 12) in the double-blind phase were to receive open-label NGM/EE for 10 additional cycles. RESULTS: For subjects completing > or =10 NGM/EE treatment cycles, mean posteroanterior total lumbar spine BMD (L1-L4) increased from 0.881+/-0.0624 g/cm2 at baseline (last visit prior to NGM/EE) to 0.894+/-0.0654 g/cm2 at final visit (p = .043); no significant changes in hip BMD occurred. Decreases in N-telopeptide, osteocalcin, procollagen type I propeptide and bone-specific alkaline phosphatase levels indicated effects on bone metabolism. CONCLUSIONS: Long-term administration of triphasic NGM/EE to osteopenic women with HA may increase total lumbar spine BMD.

Absorptiometry, Photon↗
PubMed2003

Effects of a triphasic combination oral contraceptive containing norgestimate/ethinyl estradiol on biochemical markers of bone metabolism in young women with osteopenia secondary to hypothalamic amenorrhea.

This multicenter, double-blind, placebo-controlled, randomized study of 45 patients evaluated the short-term effects of an oral contraceptive [Ortho Tri-Cyclen, 180-250 micro g of norgestimate (NGM) and 35 microg of ethinyl estradiol (EE)] on biochemical markers of bone resorption, formation, and osteoprotegerin in young women (mean age +/- SD, 26.5 +/- 6.3 yr) with hypothalamic amenorrhea and osteopenia. Body fat, endocrine, and cognitive function were evaluated as secondary endpoints. Biomarkers of bone metabolism were measured at baseline and after three cycles of NGM/EE or placebo. There were significant decreases in mean values of N-telopeptide [mean (SD), -13.4 (13.4) vs. 1.2 (23.8) nmol bone collagen equivalents (BCE)/mmol creatinine (Cr); P = 0.001] and deoxypyridinoline [-1.2 (2.9) vs. -0.5 (1.5) nmol deoxypyridinoline/mmol Cr; P = 0.021] as well as significant decreases in bone specific alkaline phosphatase [-5.1 (3.5) vs. 0.4 (3.1) ng/ml; P < 0.001], osteocalcin [-5.9 (3.6) vs. -2.9 (3.7); P = 0.016], and procollagen of type I propeptide [-35.2 (44.6) vs. -0.2 (30.0) ng/ml; P = 0.025], but not osteoprotegerin [0.39 (1.46) vs. -0.2 (0.49) pmol/liter; P = 0.397] in the NGM/EE vs. placebo group. There were no significant differences between groups with respect to changes in cognitive function, mood, body weight, body mass index, body fat, percentage of body fat, and all endocrine levels except FSH, [-3.7 (3.8) vs. -0.6 (2.1) IU/liter; P < 0.001, NGM/EE vs. placebo]. No serious adverse events were reported in either group. These results suggest that NGM/EE decreases bone turnover in osteopenic premenopausal women with hypothalamic amenorrhea. Further studies are needed to determine whether estrogen will increase bone density in this population.

Adolescent↗
PubMed2000

Detection of atrial fibrillation and flutter by a dual-chamber implantable cardioverter-defibrillator. For the Worldwide Jewel AF Investigators.

BACKGROUND: To distinguish prolonged episodes of atrial fibrillation (AF) that require cardioversion from self-terminating episodes that do not, an atrial implantable cardioverter-defibrillator (ICD) must be able to detect AF continuously for extended periods. The ICD should discriminate between atrial tachycardia/flutter (AT), which may be terminated by antitachycardia pacing, and AF, which requires cardioversion. METHODS AND RESULTS: We studied 80 patients with AT/AF and ventricular arrhythmias who were treated with a new atrial/dual-chamber ICD. During a follow-up period lasting 6+/-2 months, we validated spontaneous, device-defined AT/AF episodes by stored electrograms in all patients. In 58 patients, we performed 80 Holter recordings with telemetered atrial electrograms, both to validate the continuous detection of AT/AF and to determine the sensitivity of the detection of AT/AF. Detection was appropriate in 98% of 132 AF episodes and 88% of 190 AT episodes (98% of 128 AT episodes with an atrial cycle length <300 ms). Intermittent sensing of far-field R waves during sinus tachycardia caused 27 inappropriate AT/AF detections; these detections lasted 2.6+/-2.0 minutes. AT/AF was detected continuously in 27 of 28 patients who had spontaneous episodes of AT/AF (96%). The device memory recorded 90 appropriate AT/AF episodes lasting >1 hour, for a total of 2697 hours of continuous detection of AT/AF. During Holter monitoring, the sensitivity of the detection of AT/AF (116 hours) was 100%; the specificity of the detection of non-AT/AF rhythms (1290 hours) was 99.99%. Of 166 appropriate episodes detected as AT, 45% were terminated by antitachycardia pacing. CONCLUSIONS: A new ICD detects AT/AF accurately and continuously. Therapy may be programmed for long-duration AT/AF, with a low risk of underdetection. Discrimination of AT from AF permits successful pacing therapy for a significant fraction of AT.

Aged↗
PubMed1999

Cardiovascular collapse caused by electrocardiographically silent 60-Hz intracardiac leakage current. Implications for electrical safety.

BACKGROUND: The national standard for safe 60-Hz intracardiac leakage current under a single-fault condition is 50 microA. This standard is intended to protect patients from alternating current (AC) at levels below the threshold for sensation, but the minimum unsafe level for AC in closed-chest humans is not known. To determine this value, we studied 40 patients at testing of implantable cardioverter-defibrillators using a programmable source of 60-Hz AC. METHODS AND RESULTS: We applied AC for 5-second test periods in increasing strengths until ventricular fibrillation (VF) was induced or 1 mA was reached. Two current paths were tested: bipolar, between tip and ring electrodes of a right ventricular pacing catheter, and unipolar, from tip to a remote electrode. We observed a characteristic sequence of 3 responses as AC was increased: (1) intermittent ventricular capture with QRS morphology identical to pacing through the electrodes (minimum value, 20 microA); (2) continuous capture at cycle length 282+/-88 ms (minimum value, 32 microA); and (3) VF persisting after AC termination (minimum value, 49 microA). Continuous capture caused loss of pulsatile arterial pressure and cardiovascular collapse (mean arterial pressure, 32+/-8 mm Hg) for the duration of AC with no ECG evidence of AC stimulation. Thus, the clinical picture was that of hypotensive ventricular tachycardia (VT). The continuous-capture threshold was </=50 microA in 9 patients (22%) for bipolar AC and in 5 (12%) for unipolar AC. All patients showed continuous capture over a wide range for both bipolar AC (68+/-18 to 216+/-238 microA) and unipolar AC (84+/-27 to 278+/-226 microA). CONCLUSIONS: Leakage current causes cardiovascular collapse at levels below the VF threshold. Stimulation by silent AC that is neither felt nor visible on the ECG presents as hypotensive VT. In patients with intracardiac electrodes, leakage current less than or equal to the present standard of 50 microA may cause VT or VF. The safety standard for leakage current lasting >/=5 seconds should be </=20 microA. This standard should be based on the continuous-capture threshold.

Electric Stimulation↗
PubMed1999

Tramadol allows reduction of naproxen dose among patients with naproxen-responsive osteoarthritis pain: a randomized, double-blind, placebo-controlled study.

OBJECTIVE: To demonstrate that in patients receiving naproxen for the pain of osteoarthritis (OA), the addition of tramadol will allow a reduction in the naproxen dosage without compromising pain relief. METHODS: This trial consisted of a 5-week open-label run-in and an 8-week double-blind phase. Patients with at least moderate pain (> or =40 mm on a 100-mm visual analog scale) of OA of the knee after a 1-week medication washout were treated with naproxen 500 mg/day for 1 week. Patients whose pain scores were reduced to <20 mm were discontinued. The remaining patients received naproxen 1,000 mg/day for 3 weeks. Tramadol 200 mg/day was added during the third week. Patients were then randomized in a double-blind manner to continue tramadol 200 mg/day or to begin placebo in addition to naproxen. Randomization was stratified based on response to naproxen 1,000 mg/day. During the double-blind phase, the naproxen dose was reduced by 250 mg every 2 weeks. The primary efficacy end point was the minimum effective naproxen dose (MEND). The MEND was defined as 250 mg above the naproxen daily dosage at which pain relief was no longer adequate. Patients discontinuing the double-blind phase of the study for reasons other than lack of efficacy were assigned a MEND equal to the last naproxen dose received. If the effect of treatment between the responder and nonresponder groups was statistically different, the difference in the MEND was assessed separately within the groups. RESULTS: Of 236 patients randomized (mean age 61 years; 147 females), 90 were stratified as naproxen responders and 146 as naproxen nonresponders. There was a significant difference (P = 0.040) in the treatment effect between the naproxen responders and nonresponders, thus demonstrating a difference in the way responders and nonresponders react to a decrease in naproxen dosage after the addition of tramadol. Among naproxen responders, the MEND was significantly lower in patients receiving tramadol (n = 36) than in patients receiving placebo (n = 54), 221 mg versus 407 mg, respectively (P = 0.021). For the naproxen nonresponders, the mean MEND was 419 mg in the tramadol group and 396 mg in the placebo group (P = 0.706). CONCLUSION: In patients with painful OA of the knee responding to naproxen 1,000 mg/day, the addition of tramadol 200 mg/day allows a significant reduction in the dosage of naproxen without compromising pain relief.

Aged↗
PubMed1999

Automatic measurement of long-term heart rate variability by implanted single-chamber devices.

Heart rate variability (HRV) measurement is an established technology for the assessment of cardiac autonomic status. Recently 24 h HRV has been shown to correlate with disease severity in heart failure. This potentially makes continuous 24 h HRV measurement suitable for monitoring of heart-failure patients. Day-to-day 24 h measurement of HRV is, in principle, feasible when implemented using implanted devices (pacemakers and defibrillators) used in patients who are predominantly in the sinus rhythm. However, a number of such devices used in heart-failure patients are single-chamber devices, in which the distinction between sinus rhythm beats and ectopic beats is problematic. The study investigates whether a reasonably accurate 24 h HRV measurement can be achieved by automatic algorithms, suitable for implementation using implanted devices, without the need for identification of ectopic beats. A set of 5321 nominal 24 h Holter recordings of cardiac patients are used. Each of the recordings contains at least one ectopic beat; approximately 30% of the recordings have more than 1% of ectopic beats. Conventional 24 h measures of HRV, that is the SDNN, HRV index, and SDANN indices, are obtained from each recording after elimination of the ectopic beats and are approximated by HRV measures computed by the same formulas without exclusion of the ectopic beats. The SDANN values are also approximated by the standard deviation of 5 min medians of all RR intervals (SDMRR measure). The errors introduced by including the ectopic beats in the HRV computation were evaluated using the Bland-Altman statistics and by Cohen's kappa statistics investigating the precision of identifying patients with depressed and preserved 24 h HRV. The SDNN measure is very sensitive to the quality of the RR interval sequence and cannot be reasonably used without distinction between sinus rhythm and ectopic beats. The HRV index measure is marginally more acceptable when used without ectopic elimination. The SDANN is rather insensitive, and its replacement by SDMRR values leads to relative errors in the region of 2-5% that are almost independent of the number of ectopic beats included. Even in recordings with a substantial proportion of ectopic beats, a practically acceptable (kappa > 0.9) identification of depressed and preserved SDANN values is possible without ectopic elimination. Thus, continuous monitoring of 24 h HRV is technically feasible within implanted devices, provided the SDANN measure is monitored and either computed from the sequence of all RR intervals or, potentially preferably, replaced by the SDMRR measure.

Defibrillators, Implantable↗
PubMed1997

Gabapentin for parkinsonism: a double-blind, placebo-controlled, crossover trial.

PURPOSE: Gabapentin is a recently available anticonvulsant whose mechanism of action remains unknown. We suspected efficacy from serendipitous observations of gabapentin in patients with parkinsonism. This led us to a double-blind, placebo-controlled, crossover trial. PATIENTS AND METHODS: We administered gabapentin in a placebo-controlled, double-blind, crossover trial to 19 subjects with advanced parkinsonism. We measured the effect of placebo and gabapentin on subjects' symptoms with the Unified Parkinson's Disease Rating Scale, the Webster Scale, and the Hoehn and Yahr Scale. We assessed tremor with surface-recorded electromyography. RESULTS: Total Unified Parkinson's Disease Rating Scale improved with gabapentin compared with placebo (P = 0.0005). Likewise, activities of daily living and examination subscore of the Unified Parkinson's Disease Rating Scale improved with gabapentin compared with placebo but did not achieve statistical significance. Webster Scale showed improvement but neither Hoehn and Yahr Scale nor Webster Scale changes reached statistical significance. Tremor as measured by the Unified Parkinson's Disease Rating Scale improved with gabapentin but the use of the root mean square of the rectified electromyography as a measure of tremor activity was not statistically significant. CONCLUSIONS: This study demonstrates that gabapentin improves rigidity, bradykinesia, and tremor of parkinsonism including both Parkinson's disease and Parkinson's syndrome. The rigidity and bradykinesia of parkinsonism improve on the drug even when the effects of gabapentin on tremor are discounted.

Acetates↗
PubMed1997

Gabapentin for relief of upper motor neuron symptoms in multiple sclerosis.

OBJECTIVE: To examine the efficacy of gabapentin in the treatment of spasticity and painful muscle spasms in patients with multiple sclerosis. DESIGN: Double-blind, placebo-controlled crossover study. SETTING: Free-standing, 93-bed, university-affiliated rehabilitation hospital. PARTICIPANTS: There were 15 patients between the ages of 18 and 50 who had laboratory-supported definite multiple sclerosis with spasticity and leg cramps severe enough to interfere with daily activities, including sleep. INTERVENTION: The patients received the placebo or 400mg gabapentin orally three times a day for 48 hours with an 11-day washout period. If the patients were on currently accepted modes of therapy, including oral baclofen, their current medication was not changed. MAIN OUTCOME MEASURES: The outcome measures were Visual Faces Scale rating, Kurtzke Disability Scale, quantitative surface electromyography, Ashworth Scale, presence or absence of clonus in response to rapid ankle dorsiflexion and wrist extension, presence or absence of reflex withdrawal in response to nailbed pressure to the first finger, and assessment of Babinski response. RESULTS: Statistically significant improvements for the gabapentin treated patients were found in the Ashworth Scale, Visual Faces Scale, and Kurtzke Disability Scale. CONCLUSIONS: At a dose of 400mg orally three times a day, gabapentin may be of value in the treatment of the spasticity and painful muscle cramping experienced by patients with multiple sclerosis.

Acetates↗
PubMed1997

Norgestimate and ethinyl estradiol in the treatment of acne vulgaris: a randomized, placebo-controlled trial.

OBJECTIVE: To evaluate the efficacy of a triphasic, combination oral contraceptive (OC), (norgestimate-ethinyl estradiol), in comparison with placebo in the treatment of moderate acne vulgaris. METHODS: Two hundred fifty women were enrolled in a multicenter, randomized, double-blind, placebo-controlled clinical trial to evaluate the effectiveness of norgestimate-ethinyl estradiol in the treatment of acne vulgaris. Subjects were 15-49 years old and had moderate acne vulgaris. Each month for 6 months, subjects received either 3 consecutive weeks of active OC treatment followed by 1 week of inactive drug, or 4 consecutive weeks of color-matched placebo tablets. Efficacy was assessed by facial acne lesion counts, the investigator's global assessment, and the subject's self-assessment. Hormone levels were also measured. RESULTS: Despite the large placebo effect inherent in an acne trial (due to, for example, careful skin care, frequent office visits, regression to the mean), of the 164 subjects who completed the study without major protocol deviations, the OC group was significantly better than the placebo group for all primary efficacy measures: inflammatory lesions (mean reduction, 51.4% compared to 34.6%; P = .01), total lesions (mean reduction, 46.4% compared to 33.9%; P = .001); investigator's global assessment (83.3% compared to 62.5%; P = .001). Free testosterone decreased significantly and sex hormone-binding globulin increased significantly in the OC group, but remained unchanged in the placebo group. CONCLUSION: A triphasic combination of norgestimate and ethinyl estradiol is an effective treatment for moderate acne vulgaris in women with no known contraindication to OC therapy.

Acne Vulgaris↗
PubMed1997

Effectiveness of norgestimate and ethinyl estradiol in treating moderate acne vulgaris.

BACKGROUND: An excess of androgen is believed to contribute to development of acne in some patients. Because oral contraceptives (OCs) may reduce the active androgen level, hormonal therapy with OCs has been used successfully to treat patients with acne, although this treatment has previously not been studied in placebo-controlled trials. OBJECTIVE: Our purpose was to evaluate the efficacy of a triphasic, combination OC (ORTHO TRI-CYCLEN [Ortho-McNeil Pharmaceutical, Raritan, N.J.], norgestimate/ethinyl estradiol) compared with placebo in the treatment of moderate acne vulgaris. METHODS: Two hundred fifty-seven healthy female subjects, 15 to 49 years of age with moderate acne vulgaris, were enrolled in a multicenter, randomized, double-blind, placebo-controlled clinical trial. Each month for 6 months, subjects received either 3 consecutive weeks of the OC (i.e., tablets containing a fixed dose of ethinyl estradiol [0.035 mg] and increasing doses of norgestimate [0.180 mg, 0.215 mg, 0.250 mg]) followed by 7 days of inactive drug or placebo (color-matched tablets). Efficacy was assessed by facial acne lesion counts, an investigator's global assessment, a subject's self-assessment, and an analysis of within-cycle variation (cycle 6) in lesion counts. RESULTS: Of the 160 subjects in whom efficacy could be evaluated, the OC group showed a statistically significantly greater improvement than the placebo group for all primary efficacy measures. The mean decrease in inflammatory lesion count from baseline to cycle 6 was 11.8 (62.0%) versus 7.6 (38.6%) (p = 0.0001), and the mean decrease in total lesion count was 29.1 (53.1%) versus 14.1 (26.8%) (p = 0.0001) in the OC and placebo groups, respectively. In the investigator's global assessment, 93.7% of the active treatment group versus 65.4% of the placebo group were rated as improved at the end of the study (p < 0.001). Six of the seven secondary efficacy measures (total comedones, open comedones, closed comedones, papules, pustules, and the subject's self-assessment of study treatment) were also significantly more favorable in the OC group compared with the placebo group. CONCLUSION: An OC containing 0.035 mg of ethinyl estradiol combined with the triphasic regimen of norgestimate is a safe and effective treatment of moderate acne vulgaris in women with no known contraindication to OC therapy.

Acne Vulgaris↗
PubMed1997

Effectiveness of gabapentin in controlling spasticity: a quantitative study.

The purpose of this investigation was to study the effectiveness of gabapentin in controlling spasticity in persons with spinal cord injury (SCI) using a surface EMG-based quantitative assessment technique called the brain motor control assessment (BMCA). Six men from a Veterans Affairs Medical Center with spasticity due to traumatic SCI were studied as part of a multi-center, placebo-controlled, cross-over, clinical trial of gabapentin. Spasticity was evaluated using multi-channel surface EMG recordings of muscles in the lower extremities, abdomen and low back before and during treatment with oral gabapentin or placebo. Gabapentin or placebo was given orally in doses 400 mg three times daily for 48 h. Following a 10 day wash-out period subjects were crossed-over to receive the medication not received the first time. This was followed by an elective open-label extension. Group results during the controlled trial did not reach statistical significance at the dosage used. One subject demonstrated a dramatic improvement in spasticity that was apparent both clinically and with the BMCA. Other subjects demonstrated modest improvements which were seen in the BMCA but not recognized clinically. During the open label extension, the four subjects who participated experienced important clinical improvements with higher doses (to 3600 mg/day). These improvements were often in components of spasticity in which the BMCA had detected subclinical changes during the cross-over trial. A seventh subject was studied using the BMCA at doses of 1200 mg T.I.D. gabapentin, off gabapentin and 800 mg T.I.D. gabapentin and demonstrated quantitatively a dose-related effect with higher doses of gabapentin which matched clinical observations. Gabapentin at doses of 400 mg T.I.D. may be effective in controlling some features of spasticity in persons with SCI. Higher doses provide greater control of spasticity, and controlled studies using higher doses are needed to evaluate gabapentin's efficacy.

Acetates↗
PubMed1997

Gabapentin for the treatment of spasticity in patients with spinal cord injury.

Our serendipitous observations suggested that some patients with spasticity appeared to have improved following the administration of the anticonvulsant drug gabapentin. As some patients with spasticity are either refractory to or intolerant of established medical treatments, we conducted this study to investigate the effect of gabapentin on spasticity in patients with spinal cord injury. Twenty-five patients with spinal cord injury and spasticity received oral gabapentin (2400 mg over 48 h) in a randomized, double blind, placebo-controlled crossover study. We assessed responses by measuring the Ashworth spasticity scale, muscle stretch reflexes, presence of clonus and reflex response to noxious stimuli. Patient ratings were obtained using a Likert Scale. Administration of gabapentin, but not placebo, was associated with an 11% reduction in spasticity as measured by the Ashworth Scale (P = 0.04) and by a 20% reduction in the Likert Scale (P = 0.0013). Significant changes were not obtained for the other measures. The data obtained suggest that gabapentin may be useful in the management of spasticity associated with spinal cord injury.

Acetates↗
PubMed1989

Effect of diltiazem on 2,4-D-induced myotonia in rats.

Myotonia is characterized by prolonged contraction (delay in onset of relaxation) of skeletal muscle fibers with characteristic electromyographic findings. Calcium channel blocking drugs may be expected to reduce myotonia, should they promote the onset of relaxation in a contracted skeletal muscle. This study was aimed at evaluating the effect of diltiazem, a calcium channel blocking agent, on myotonia induced by 2,4-dichlorophenoxyacetic acid (2,4-D). In rat diaphragm, exposed to 2.5 mM 2,4-D in a tissue bath, myotonia was quantified by documenting the contraction time in response to direct stimulation with supramaximal electric stimuli. At the peak of myotonia, different concentrations of diltiazem were added to the tissue bath and the effect on evoked contraction studied over a period of 6 minutes. A concentration of 5 x 10(-5) M was found to be the most effective, causing a decrease in contraction time of more than 90% in 3 minutes in 100% of specimens (n = 7). The above findings raise the possibility of using diltiazem as an antimyotonic agent.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1987

Bone marking for biopsy using radionuclide bone imaging.

If bone biopsies are performed after the sites are located under radionuclide guidance, the chances of sampling the pathologic tissue are greatly improved. After bone scanning, two to three areas for biopsy are chosen and locating is done with 0.05 ml of Tc-99m in a tuberculin syringe under an Anger camera. Methylene blue-xylocaine is injected into the skin up to the periosteum for marking the site of the biopsy. Using this technique, 27 biopsies in 20 patients have been performed (four were open and 23 were closed needle). Pathology was found in 25 biopsies (92.6%), cancer in 22 (81.5%), benign lesions in three (11.1%), and normal bone in two (7.4%).

Adult↗
PubMed1986

Temporal stability of sequential pulse defibrillation threshold.

We have shown that sequential pulse defibrillation threshold voltage and total delivered energy do not change with maturation of the electrode tissue interface for up to 12 weeks after implantation of two different electrode configurations. This result is important to predict the future performance of an implantable defibrillator that is tested only at implant.

Animals↗