Biomedical subjects

J Tweed

Publications and source records attributed to J Tweed.

6 recordsLinked to original sources

PubMed2002

A simple model for straggling evaluation.

Some straggling models had largely been abandoned in favor of Monte Carlo simulations of straggling which are accurate but time consuming, limiting their application in practice. The difficulty of simple analytic models is the failure to give accurate values past 85% of the particle range. A simple model is derived herein based on a second order approximation upon which rapid analysis tools are developed for improved understanding of material charged particle transmission properties.

Alpha Particles↗

PubMed2000

Zotepine in the prevention of recurrence: a randomised, double-blind, placebo-controlled study for chronic schizophrenia.

RATIONALE: Zotepine is an antipsychotic drug with proven efficacy for treatment of acute episodes of schizophrenia. Antipsychotic drugs also require to be effective in prevention of recurrence. OBJECTIVE: This trial was designed to compare the effects of zotepine and placebo in the prevention of recurrence of acute episodes in a population of patients with chronic schizophrenia. METHODS: The study was a double-blind, parallel group, 26-week comparison of zotepine (300 mg daily, with fall back to 150 mg if necessary) versus placebo in 121 patients with chronic schizophrenia and a history of recurrence in the previous 18 months. The primary outcome measure was the time to recurrence. Other evaluations included the brief psychiatric rating scale (BPRS), the scale for the assessment of negative symptoms (SANS), the clinical global impression (CGI) severity and improvement scales, and the Simpson and Angus scale for extrapyramidal symptoms (EPS). RESULTS: Fewer zotepine patients experienced recurrence over 26 weeks than placebo patients (4 versus 21, respectively). The estimated 26-week risk of recurrence was six times lower for zotepine than placebo (8.7% versus 52.8%; hazard ratio 0.16, 95% CI 0.053, 0.484; P<0.001). Scores on the BPRS and CGI supported the efficacy of zotepine. There was no difference between the treatments with respect to EPS. CONCLUSIONS: Zotepine is effective in preventing recurrence in patients with chronic schizophrenia. The level of EPS was not different between zotepine and placebo.

Adolescent↗

PubMed2000

A placebo-controlled comparison of zotepine versus chlorpromazine in patients with acute exacerbation of schizophrenia.

OBJECTIVE: The aim of this study was to evaluate the efficacy of zotepine in the treatment of acute episodes of schizophrenia. METHOD: Patients with acute exacerbation of schizophrenia (DSM-III-R criteria; n = 158) were allocated on a random, double-blind basis to receive zotepine (150 or 300 mg/day), chlorpromazine (300 or 600 mg/day) or placebo for 8 weeks. Symptoms were assessed on the BPRS, SANS and CGI scales at baseline and weeks 1, 2, 4, 6 and 8 and patients were assessed at these times for adverse effects. Analysis was by analysis of variance on the intent-to-treat population, with last observation carried forward. RESULTS: Mean BPRS scores improved statistically significantly more with zotepine than chlorpromazine (point estimate of difference -12.4, 95% CI -18.3 to -6.5) or placebo (point estimate of difference -12.7, 95% CI -18.6 to -6.8). Zotepine produced significantly fewer extrapyramidal symptoms (EPS) than chlorpromazine. CONCLUSION: Zotepine is an effective antipsychotic with low propensity for EPS.

Acute Disease↗

PubMed1996

A comparison of an atypical and typical antipsychotic, zotepine versus haloperidol in patients with acute exacerbation of schizophrenia: a parallel-group double-blind trial.

The atypical antipsychotic zotepine was compared to haloperidol in 126 patients suffering from acute exacerbation of schizophrenia (DSM-III-R) in a randomized, double-blind study. After 8-weeks, 150 to 300 mg zotepine improved scores on the Brief Psychiatric Rating Scale (BPRS) more than 10 to 20 mg haloperidol (-17.03 versus -13.45; 95%CI for zotepine-haloperidol -9.34/2.04). BPRS subscores and Clinical Global impressions (CGI) Severity and improvement subscales showed comparable gains, but scores on the Scale for the Assessment of Negative Symptoms (SANS) improved significantly more with zotepine (-23.82) than haloperidol (-15.15; P < .05; 95%CI for zotepine haloperidol -18.03/-0.18). Adverse events were reported by 71 percent of zotepine and 78 percent of haloperidol patients. Extrapyramidal side effect (EPMS) scores decreased with zotepine (-0.34) but increased with haloperidol (+2.32; P < .05). Seven haloperidol patients reported akathisia but no zotepine patients did (p < .05). Uric acid reductions (which appear to have no clinical consequence) and transient raised liver enzymes were recorded with zotepine. Weight increased on zotepine (2.32 kg; P < .001) and a small increase in pulse rate occurred (P < .05). Both drugs were effective in reducing positive symptoms of schizophrenia; zotepine was significantly more effective against negative symptoms and reduced EPMS.

Adult↗

PubMed1995

An investigation into sound attenuation by earmould tubing.

A major problem in high-gain post-aural hearing aids is acoustic feedback. One of the sources of feedback is the plastic tubing that guides the sound from the hearing aid hook to the ear canal. The objectives of this study were to determine the effects of increases in tubing wall thickness on the amount of acoustic feedback in the hearing aid system and to characterize earmould tubing. Five different samples of Tygon tubing were tested, of which four had different wall thicknesses; the study also compared Tygon tubing with medical grade PVC tubing. Measurement of the wall thickness, taken from scanning electron micrographs, showed that the wall thickness differed from the National Association of Earmould Laboratories standard by less than 6% and was well within the manufacturer's tolerances. Measurement of sound attenuation showed that an increase in the tubing wall thickness of 0.330 mm (Tygon 13 Standard to Tygon 13 Double Wall) caused an increase in sound attenuation of 2 dB, across the frequency range measured (0.5-4 kHz). It was also found that the medical grade PVC had a 5 dB greater sound attenuation than the equivalent Tygon tubing. While these differences are quite small, they could contribute to a reduction in acoustic feedback when used in conjunction with other hearing aid or earmould improvements.

Acoustics↗

PubMed1989

A new exercise test for the assessment of heart failure: use of a self powered treadmill.

Time limited exercise on a self powered treadmill was evaluated as a method of assessing functional capacity in patients with mild heart failure. The characteristics of the treadmill were established by exercising 11 controls at three speeds and two inclinations and comparing oxygen consumption with that on a motorised treadmill under the same conditions. Oxygen consumption on the self powered treadmill at an equivalent speed and inclination was significantly higher because of the work needed to overcome the friction of the belt. Unlike a conventional treadmill, increasing the gradient on the self powered treadmill did not increase oxygen consumption. The distance walked in 12 minutes on the self powered treadmill was measured in eight patients with mild heart failure and ten controls. Maximal oxygen consumption was measured in the same group on a conventional treadmill by a mass spectrometer. There was a significant correlation between the distance walked and maximum oxygen consumption. In patients with mild heart failure the distance travelled in 12 minutes on a self powered treadmill provides a practical, inexpensive, and sensitive method of assessing functional capacity.

Aged↗