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Biomedical subjects

J Soto

Publications and source records attributed to J Soto.

At least 145 records · Page 8Linked to original sources
PubMed1992

Oxidative decarboxylation of naproxen.

The decarboxylation of naproxen (1H) and its salt (1-) was achieved by means of chemical [Ce(IV) or S2O8(2-)] and electrochemical oxidation. The product patterns were compatible with mechanisms involving single-electron transfer from the pi-system or the carboxylate moiety. The results are discussed in connection with the involvement of electron-transfer processes in the reported phototoxicity of naproxen.

Electrochemistry↗
PubMed1992

[The hepatic porphyrias: experience with 105 cases].

Hepatic porphyria is a rare metabolic syndrome caused by abnormal enzyme activity in heme biosynthesis. Between 1974 and 1991; 105 patients have met criteria for diagnosis of hepatic porphyria based on typical clinical findings and/or laboratory abnormalities. According to type, 42% had porphyria cutanea tarda, 21% porphyria variegate, 15% protoporphyria, 6.7% acute intermittent porphyria, 6.7% coproporphyria and 1.9% porphyria due to porphobilinogen deficit. A proper classification was not established in 6.7% of patients. Porphyria cutanea tarda was more common in males (70%) and porphyria variegata, in females (90%). A family history of the disease was present in 33% of patients; 20% of patients were of European descent and 4% of Mapuche descent. Diagnosis was usually established in the third decade, somewhat later in porphyria cutanea tarda (45 years of age) and very early in protoporphyria. 10% of patients were asymptomatic and 29 patients developed at least one porphyric crisis. These were related to pregnancy in 6 patients, to hormone administration in 7, to antibiotics in 5. No cause was established in 21 cases. Severe crisis were successfully treated with Hematin. Venipuncture was used to treat 50% of patients with porphyria cutanea tarda with 95% success. Thus, hepatic porphyria is recognized with increasing frequency and can be treated successfully in most cases.

Adolescent↗
PubMed1992

[Initial dosage of vancomycin in neutropenic hematologic patients].

PURPOSE: To evaluate the percentage of neutropenic patients who reach the therapeutic threshold when vancomycin is given at standard initial doses of 500 mg/6 hr, and to assess the creatinine clearance and body vancomycin clearance in such patients. MATERIAL AND METHODS: The study was performed on 37 haematological patients with normal renal function. They received intravenous vancomycin at an initial 500 mg/6 hr doses. The plasma concentration of the drug was assessed 48-72 hr later, pharmacokinetic parameters being calculated. Creatinine clearance was estimated by two different methods. RESULTS: The concentration attained was beyond the therapeutic threshold in 100% of the patients. The correlations between vancomycin and creatinine clearance were r = 0.42 and r = 0.47 when the Cockroft-Gault's and the Jellife's methods, respectively, were used. Administration of vancomycin at initial doses of 500 mg/6 hr renders a very high percentage of patients with plasma concentration of the drug beyond the therapeutic margin. CONCLUSIONS: 1) The poor correlation between creatinine and vancomycin clearance in the patients with normal renal function does not allow using nomograms based on such values for estimation of the initial doses. 2) The estimation of initial doses based on the patient's weight (20-25 mg/kg) may render a higher percentage of patients with therapeutic concentrations from the beginning of treatment. The maintenance doses can be adjusted at 48-72 hr, after measuring the plasma concentrations. 3) Therefore, it seems advisable to perform further clinical assays on different groups in order to verify an increase of the drug's efficacy with no higher toxicity when the initial vancomycin doses is adjusted according to the patient's weight, as recommended here.

Adolescent↗
PubMed1991

A modified Lucas cell for leakage measurement from encapsulated radium sources.

A new method to determine the leakage rate from encapsulated radium sources is proposed. The method is based on the principle of enclosing the source to be tested in a hermetically sealed container and measuring the radon radioactivity growth in the container as a function of time. A cylindrical modified Lucas cell, designed and built in our laboratory, is used for measuring the radon which are done by ZnS(Ag) alpha scintillation counting and can be easily compared with existing standard for leak tests. Results obtained show the applicability of the method for leak testing for radon leakage from sealed radium sources.

Kinetics↗
PubMed1991

Diagnosis of Lafora's disease in apocrine sweat glands of the axilla.

A case of Lafora's disease diagnosed by skin biopsy is reported. Lafora's bodies, the hallmark of myoclonal epilepsy, were present in the epithelial cells of the apocrine glands. Therefore, the skin biopsy of the axilla proved to be very useful in the diagnosis of this entity. A striking feature of the case was that Lafora's bodies were only found in apocrine glands, whereas the eccrine glands were free of them.

Adult↗