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Biomedical subjects

A Vyth

Publications and source records attributed to A Vyth.

9 recordsLinked to original sources
PubMed1996

Survival in patients with amyotrophic lateral sclerosis, treated with an array of antioxidants.

Between 1983 and 1988 we treated 36 patients with sporadic amyotrophic lateral sclerosis (ALS) by an array of antioxidants and added other drugs to the regimen whenever a patient reported deterioration. Our customary prescription sequence was N-acetylcysteine (NAC); vitamins C and E; N-acetylmethionine (NAM); and dithiothreitol (DTT) or its isomer dithioerythritol (DTE). Patients with a history of heavy exposure to metal were also given meso 2,3-dimercaptosuccinic acid (DMSA). NAC, NAM, DTT, and DTE were administered by subcutaneous injection or by mouth or by both routes, the other vitamins and DMSA by mouth alone. The hospital pharmacy supplied NAC and NAM injections fluid as 100 ml bottles of 5.0 and 5.85% solutions, respectively. DTT was delivered in special double-walled capsules of 200 mg. DTT/DTE injection fluid was added to the NAC and NAM bottles, the final DTT/DTE concentrations never exceeding 0.5%. DMSA was provided in 250 mg capsules. All of the 36 patients used NAC and DTT/DTE; 29 also used vitamins C and E; 21 also used NAM; and 7 also used DMSA, DMSA, NAM, vitamins C and E were tolerated well. In many patients, DTT, DTE, NAC and NAM induced pain, redness and swelling at the injection sites in that order of decreasing frequency. DTT and DTE did often and NAC did sometimes cause gastric pain, nausea and other abdominal discomfort. Comparison of survival in the treated group and in a cohort of untreated historical controls, disclosed a median survival of 3.4 years (95% confidence interval: 3.0-4.2) in the treated and of 2.8 (95% confidence interval 2.2-3.1) years in the control patients. This difference may be explained by self-selection of our highly motivated treated group and by its initial survival of diagnosis for an average of 8.5 months before onset of treatment. We conclude that antioxidants neither seem to harm ALS patients, nor do they seem to prolong survival.

Acetylcysteine↗
PubMed1987

Cerebral blood flow imaging with thallium-201 diethyldithiocarbamate SPECT.

Thallium-201 diethyldithiocarbamate ([201TI]DDC) was studied in humans as an agent for cerebral blood flow imaging. Brain uptake proved to be complete 90 sec after injection with no appreciable washout or redistribution for hours. Intracarotid injection suggested an almost 100% extraction during the first passage. Whole-body distribution studies demonstrated a brain uptake of 4.3% of the dose compared with 0.9% for [201TI]chloride. No differences were found in the distribution of [201TI]DDC versus [201TI]chloride in other organs. After the injection of 3 mCi 201TI, good quality single photon emission computed tomographic (SPECT) images of the brain were obtained with both a rotating gamma camera and a multidetector system. In ischemic brain disease, perfusion defects were easily demonstrated. We conclude that [201TI]DDC is a suitable radiopharmaceutical for SPECT studies of cerebral blood flow.

Aged↗
PubMed1985

Thallium-201 diethyldithiocarbamate: an alternative to iodine-123 N-isopropyl-p-iodoamphetamine.

The study of cerebral blood flow by single photon emission computed tomography (SPECT) requires lipophilic radiopharmaceuticals. The high cost and limited availability of N-isopropyl-p-[I-123]-iodoamphetamine ( [123I]IMP) led us to search for alternatives. Following our recent development of thallium-201 diethyldithiocarbamate ( [201TI]DDC), we have compared the brain uptake of [123I]IMP and [201TI]DDC in rabbits. The brain bound 1.14 +/- 0.28% (s.e.m.) of the dose of the injected [123I]IMP and 1.46 +/- 0.28% of the [201TI]DDC. Brain activity of [201TI]DDC remained stable from 1.5 min after injection up to at least 1 hr. The [201TI]DDC uptake was more instantaneous than that of [123I]IMP. The ratios of gray to white matter distribution were about equal: 1.41 for [123I]IMP and 1.44 for [201TI]DDC. The lungs retained 8.32% of the dose of [123I]IMP and only 0.53% of the [201TI]DDC. In brain macroautoradiography [201TI]DDC yielded images of good quality with excellent demarcation of gray and white matter, persisting for at least 45 min after injection. We conclude that [123I]IMP and [201TI]DDC are equally suitable for blood flow study of the rabbit brain. The first human tomographic results obtained in two healthy volunteers demonstrate that clinical application of SPECT [201TI]DDC may be feasible.

Amphetamines↗
PubMed1983

201Tl-diethyldithiocarbamate: a possible radiopharmaceutical for brain imaging.

For estimating regional brain perfusion with a gamma camera lipophilic radiopharmaceuticals are required. This paper describes the development of 201Tl-diethyldithiocarbamate (201TlDDC). First the compound NaDDC was tested for stability and an assay was developed. Next the 201TlDDC complex was prepared and checked for lipophilicity and stability by paper chromatography. A scintigraphic pilot study using this agent in a rabbit showed considerable brain uptake, compared to 201TlCl. Finally we performed a study in rats on the distribution of 201TlDDC in different organs. The results confirmed the lipophilicity of the agent. Within the first hour the percentage of injected dose per gram tissue was 2.73% in the cerebrum and 1.35% in the cerebellum. These data are in good agreement with some other agents used for assessment of brain blood flow.

Animals↗
PubMed1983

Formulation of a stable vidarabine infusion fluid.

Decomposition of vidarabine in a 5% glucose infusion fluid after steam sterilization was measured by HPLC and TLC analysis. After sterilization for 60 minutes at 100 degrees C and 20 minutes at 120 degrees C no degradation could be observed. A slight but significant degradation was observed after sterilization for 60 minutes at 120 degrees C followed by storage for eight months. Assuming 5% loss of content to be acceptable, it was concluded that a vidarabine infusion fluid can be sterilized for 20 minutes at 120 degrees C and stored at room temperature for at least eight months afterwards.

Adenine↗
PubMed1982

Colorimetric determination of tin(II) levels in 99mTc labelling kits.

A rapid quantitative test for determination of stannous tin in kit preparations is described. After addition of phosphomolybdate a blue colour is measured at 700 nm. Sn2+ levels in pyrophosphate, MDP, DTPA, diethyl HIDA, dimethyl HIDA, glucoheptonate, phytate and tin colloid kits were determined. In many kits these levels proved to be rather low. Results from the colorimetric test were comparable with those obtained by iodometric titration. During exposure to the air by extensive stirring, Sn2+ preparations showed rapid deterioration which could be prevented by adding ascorbic acid. This simple test is a valuable method to determine Sn2+ levels in many kit preparations and can be useful in the investigation of factors that contribute to the decrease of the Sn2+ content.

Colorimetry↗
PubMed1981

Intravenous naphazoline intoxication.

Nine pale perspiring drug addicts with drowsiness, nausea, headache, normal blood pressure and marked sinus bradycardia with premature ventricular beats were seen at the Casualty Department soon after alleged i.v. cocaine administration. Eight were treated with atropine, as the bradycardia suggested intoxication with a parasympathomimetic compound. Seven were discharged in good condition after a few hours' observation. One patient developed a blood pressure of 150/120 mmHg after atropine. Subsequently, a hemiparesis was found and an intracerebral haematoma was evaluated at surgery. Another patient was admitted forthwith to the CCU. He did not receive any medication and recovered within two days. Urinalysis of these two patients disclosed contents of naphazoline, a powerful alpha-adrenergic agent. Samples of the alleged cocaine contained 97% naphazoline HCl. A conscious rabbit was injected with naphazoline and thereafter with atropine. I.v. naphazoline doubled mean arterial pressure (MAP) and reduced heart rate (HR) from 167 to 30 beats/min. Atropine doubled HR, but caused a marked rise in MAP, too, stressing the adverse effects of atropine in these cases. When confronted with patients after alleged cocaine abuse, the role of substitute drugs, especially alpha-adrenergic compounds, should be considered as this should influence the therapeutic approach.

Adult↗