The Use of Radioreceptor Assays for the Determination of Benzodiazepines in Biological Samples: A Review

Benzodiazepines are the most widely prescribed class of psychotropes. The demonstration of specific, high affinity binding sites for benzodiazepines in mammalian brain has provided a basis for a radioreceptor assay (RRA) of these compounds in biological samples (fluids or tissues). The RRA permits the simultaneous measurement of the benzodiazepine molecules that bind to the receptor, providing a total estimate of all pharmacologically active forms of the drug, which is useful in drug monitoring and in the intensive care of patients. After a complete description of the methodological aspects of this technique, the results obtained in therapeutic monitoring and in toxicological analysis are reviewed, and the advantages and disadvantages of this method are examined.

Repeated doses of activated charcoal and cholestyramine for digitoxin overdose: pharmacokinetic data and urinary elimination

A 48-year-old man chronically treated with digitoxin and verapamil for prevention of atrial fibrillation voluntarily ingested 2.2 mg of digitoxin. Serum digitoxin concentrations and the urinary elimination of the drug were followed over a 12-day period. Urinary data indicate that a large percentage (50%) of the drug was eliminated renally despite administration of multiple doses of activated charcoal, cholestyramine and hyperosmotic laxatives. The possible interaction with two other drugs, heparin and verapamil, is also discussed.

Amrinone for refractory cardiogenic shock following chloroquine poisoning

Cardiac arrhythmias and circulatory collapse account for the high mortality reported after severe chloroquine poisoning. We have recently observed a 17-year-old man who ingested an 8 g chloroquine overdose. Cardiac arrest occurred within 1 h. Cardiogenic shock was refractory to epinephrine, dopamine and molar sodium lactate. Amrinone, a bipyridine analog, was then successfully used to improve haemodynamic conditions.

Hereditary hepatic porphyria due to homozygous delta-aminolevulinic acid dehydratase deficiency: studies in lymphocytes and erythrocytes

Activities of delta-aminolevulinic acid (ALA) dehydratase and porphobilinogen (PBG) deaminase, and haem content were determined in EB-virus transformed lymphocytes from two patients with homozygous ALA dehydratase deficiency, and their family members to determine the expression of the specific gene defect in this cell type. ALA dehydratase activity, but not PBG deaminase activity or haem content, was markedly decreased in lymphocyte preparations from both patients with homozygous enzyme deficiency, and moderately decreased in subjects heterozygous for enzyme deficiency. Immunochemical quantitation of erythrocyte ALA dehydratase suggested the presence of a cross-reactive material in a patient with a late-onset of acute hepatic porphyria due to the homozygous enzyme deficiency.

[Association of idiopathic hemochromatosis and tardive cutaneous porphyria]

Porphyria cutanea tarda is a disorder of porphyrin metabolism that results from a deficiency of uroporphyrinogen decarboxylase, resulting in a characteristic pattern of porphyrin excretion. Elevated serum iron values are frequently observed among patients with porphyria cutanea tarda. The hypothesis has been advanced that a hemochromatosis allele is implicated in the clinical manifestation of porphyria cutanea tarda. We report the case of a patient suffering from both idiopathic hemochromatosis and porphyria cutanea tarda. The data of the medical literature concerning such an association are discussed.

Porphyric neuropathy and hereditary delta-aminolevulinic acid dehydratase deficiency in an adult

A man without a history of porphyric attacks developed a subacute motor neuropathy at the age of 63. At the same time the first signs of a myeloproliferative disorder were found. He had a homozygous deficiency of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) with autosomal recessive inheritance. Treatment with parenteral glucose and with hematin had a beneficial influence on the plasma ALA levels. The finding of a motor neuropathy with increased plasma levels of ALA but not of porphobilinogen (PBG) supports the potential role of ALA in the pathogenesis of porphyric neuropathy.

Biochemical diagnosis of an hereditary aminolaevulinate dehydratase deficiency in a 63-year-old man

Porphyrin metabolism was investigated in a 63-year-old male patient who developed a subacute onset polyneuropathy with predominance of motor signs in the upper limb. The screening for lead, cadmium, mercury, aluminum and thallium was negative. The study of porphyrin metabolism showed remarkable abnormalities, particularly a very high level of plasmatic 5-aminolaevulinic acid contrasting with a normal level of porphobilinogen and a nearly complete loss of activity of aminolaevulinic acid dehydratase with no regenerative response to dithiothreitol or zinc ions. The other causes of aminolaevulinic acid dehydratase deficiency (tyrosinaemia, alcoholism, smoking, cirrhosis, renal insufficiency, diabetes mellitus) were ruled out. The diagnosis of primary aminolaevulinic acid dehydratase deficiency was proposed and confirmed by the familial study, which revealed the existence of several heterozygous members in this family.

Erythropoietic protoporphyria in a child

Erythropoietic protoporphyria (EPP), a recently described form of porphyria, often remains unrecognized. We report the case of a 7-year-old girl admitted for investigation of photosensitivity since the age of 18 months without any significant objective cutaneous lesions. Clinical features, quantitative determinations of porphyrins in blood, urine and stools, ferrochelatase activity and cutaneous histopathology helped to confirm the diagnosis of EPP. A familial study was also performed. The clinical, laboratory and genetic characteristics of EPP are reviewed.

Predictors of methanol intoxication with unfavourable outcome

In 10 adult patients acutely intoxicated with methanol, the base deficit and the total blood CO2 were highly correlated with blood formate level. No correlation was found between the same parameters and blood methanol level. Formate production is the main cause of acidosis in the early stages of methanol poisoning. The association of a latency period before treatment exceeding 10 hours and a blood formate level above 0.5 g/l (11.1 mmol/l) is predictive of severe methanol poisoning possibly leading to permanent sequelae.

[Diffuse pulmonary contusion]

Seventy-two cases of diffuse pulmonary contusion, 50 of which concerned multiple injury patients, are retrospectively described. The pleuro-parietal and associated lesions, the clinical, radiological and laboratory findings and the extent of the damage are analyzed. Treatment of shock (50 cases), mechanical ventilation (51 cases), thoracotomy (7 cases) and surgery of associated lesions are studied. Morbidity and mortality (34.7%) are detailed. The nosology of pulmonary contusion is discussed in relation to several factors, including shock, perfusions and associated lesions. The principles of treatment are restated. The most important complication is pulmonary superinfection. Diffuse pulmonary contusion is a serious condition. Associated lesions and their treatment contribute to its outcome.

Effect of aluminum on porphyrin metabolism in hemodialyzed patients

In patients with renal failure and on chronic hemodialysis, serum aluminum, serum delta-aminolevulinic acid, serum porphobilinogen and erythrocyte zinc protoporphyrin (ZPP) are significantly elevated, whereas erythrocyte delta-aminolevulinic acid dehydratase activity (ALAD, values in percent) is significantly reduced. The last two parameters (ZPP and ALAD) are statistically related to serum aluminum concentration (Al-S), but only the correlation between Al-S and ALAD remains statistically significant after standardization for the degree of renal insufficiency (expressed in terms of urea level). This study does not support the hypothesis that the retention of aluminum is responsible for the increase of ZPP in uremic patients on dialysis. The disturbances of porphyrin metabolism found in patients with renal failure and on chronic dialysis are not similar to those observed in porphyria cutanea tarda.

[Clinical value of rapid bacteriological results in nosocomial infections. Comparison with traditional methods]

With automated analysers, bacterial identification and susceptibility testing can be performed in 4-5 hours instead of 12-18 hours with conventional methods. A controlled trial was carried out in the surgical ward of a university hospital to evaluate the clinical repercussions of these rapid methods. The automated analyser reduced delays in the laboratory by about 25%, and optimizing information transfer from laboratory to ward brought the reduction up to 50%. It was found that earlier results of susceptibility testing modified prescriptions and this may be expected to result in a more rational use of antibiotics.

The medical and economic consequences of automation in bacteriology: a case study in a French university hospital

In a bacteriology laboratory where automated and non-automated procedures co-existed during the study period (1 year), patients were randomly assigned to each type of procedure and we observed the physicians behaviour as well as patients well-being in a surgical service using the results from the laboratory. Contrary to our expectations, the reduction in the time delay necessary to obtain information did not alter either the prescribing behaviour of physicians nor the welfare of patients. Besides, the gain in time was significantly lower than expected. We also discuss in detail the meaning and relevance of the results.

Glucose homeostasis in rats acutely and chronically treated with chloroquine

Glucose homeostasis of normal rats was studied after chronic or acute administration of chloroquine. Male rats received, in drinking water, a daily dose of 5-20 mg chloroquine/kg, for 20 weeks. The high dose caused a slight decrease in food intake and weight gain. In these animals, plasma glucose levels were somewhat lower than in controls after an overnight fast and after oral administration of glucose or intravenous administration of insulin, but not after intravenous administration of glucose. Their insulin response to oral or intravenous glucose was normal. The insulin content of their pancreas was decreased by about 15%. Electron microscopy revealed the presence of myeloid bodies and numerous lysosomes in B cells. Acute intraperitoneal administration of chloroquine was without effect on glucose tolerance and insulin release. This study shows that chloroquine, at plasma concentrations similar to those reached in treated patients, does not impair glucose homeostasis in normal rats.

Acute diquat intoxication. Interest of its repeated determination in urine and the evaluation of renal proximal tubule integrity

A 33-year old farmer ingested approximately 300 ml of a 20% solution of diquat along with about 80 mg flunitrazepam. The patient presented neurological (coma grade I), digestive (oro-pharyngeal erosions, ileus), hepatic (cytolysis), hematological (thrombopenia) and renal (tubular dysfunction) signs. Plasma creatinine did not exceed 1.22 mg/dl (upper normal value), but retinol binding protein level in urine (a marker of renal tubular dysfunction) reached a value of 337 mg/d (normal values less than 300 micrograms/d). Its level returned to normal value 18 days after the ingestion. Four hours after the poisoning, diquat level in blood amounted to 10.4 mg/l, but its level was below the detection limit (0.2 mg/l) 6 hours later. In urine, however, diquat was detected until day 13. The following therapy was applied: ventilation (FiO2:0.21), gastro-intestinal lavage, hemoperfusion, anti-oxidants and prolonged forced diuresis. The patient made an uneventful recovery. intestinal washout must be applied with caution since an ileus is a classical complication of diquat poisoning. Hemoperfusion was found to be of little value. The interest of prolonged application of forced diuresis is suggested by the detection of diquat in urine for about 2 weeks along with the presence of biological signs of renal tubular dysfunction.

Severe and prolonged poisoning by fenthion. Significance of the determination of the anticholinesterase capacity of plasma

A case of acute poisoning by oral ingestion of fenthion is reported. The different clinical signs, especially the delayed and prolonged symptomatology, are described. The various types of therapeutic measures (gastric lavage with charcoal, administration of atropine, Toxogonine, lyophilized human cholinesterase, and fresh plasma and exchange transfusion) are discussed. Correlation studies between clinical signs and plasma and erythrocyte cholinesterase activities are presented together with plasma fenthion levels and the anticholinesterase capacity of the patient's plasmas.

Delayed sulfhemoglobinemia after acute dapsone intoxication

A case of acute Dapsone intoxication due to voluntary ingestion of 3 g of this drug as a suicide attempt is described. A severe methemoglobinemia developed, accompanied by intense cyanosis, dyspnea, headache, and nausea. Subsequently, significant sulfhemoglobinemia responsible for prolonged cyanosis was observed, as well as mild hemolytic anemia. Relapses of methemoglobinemia after methylene blue treatment required repeated administration of the reducing agent. The need of a careful follow-up for several days in this type of intoxication is emphasized.

[Myasthenia gravis and thymectomy. Report of forty cases (author's transl)]

Forty operated cases of myasthenia gravis correspond to 14 thymomas, 18 hyperplasias and 8 vestigial thymus : 3 stages, I, 28 stages, II, 6 stages III, 3 stages IV. For vestigial thymus and moderate hyperplasias, cervicotomy was used in 11 cases. Surgery allowed 15 remissions, 12 ameliorations, 11 failures, aggravations and late deaths, and 2 post-operative deaths (one of them avoidable). Apart from its oncologic interest in thymomas (1/3 of the patients), thymectomy is beneficial in 2/3 of the cases of myasthenia gravis in general.

[Serum lipase assay for clinical use. Critical study (author's transl)]

An accurate, quick, and reproducible method to assay serum lipase activity allowed a parallel study of lipase and amylase in 147 patients. Lipase appeared very specific of pancreatic distress. In acute pancreatitis its increase was constant, frank, quick and lasting. It brought a diagnostic argument superior to the dosages of amylase activities in serum and/or urine. But its value as an evolutive and pronostic test was as much limited. Its interest as a negative argument for differential diagnosis was not superior either. In chronic pancreatic diseases, it gave evidence of massive spread or complications.

[A rapid and simple method for the qualitative and quantitative determination of hexapropymate in biological fluids and organs (author's transl)]

The method is based mainly on the extraction of the substance by a small volume of organic solvent from an alkaline medium containing a fairly important amount of inorganic salt. The extract is then subjected to thin layer and/or gas chromatography. The authors present also the relative frequency that they met on hexapropymate intoxications together with the concentrations in blood obtained in cases accompanied with deep coma.