Aeromonas hydrophila and its relation with drinking water indicators of microbiological quality in Argentine.

In Argentine, water municipal supplies disinfection is carried out by chlorine. We have isolated Aeromonas hydrophila from a chlorinated water supply in Buenos Aires that fulfilled Argentinean microbiological quality standards. It is an aquatic organism that could produce cytotoxins and enterotoxins associated with acute gastroenteritis and wound infections in human and hemorrhagic septicaemia of fish, reptiles and amphibians. The isolated strain produced protein bands at isoelectric point in the range of 4.6-5.3 lightly labile at 56 degrees C and heat labile at 100 degrees C non cholera antitoxin reactive in electrofocusing assay (IEF) and showed hemolytic activity thermolabile at 56 degrees C and 100 degrees C in 5% rabbit erythrocytes in phosphate buffered saline. A cytotoxic effect thermolabile at 56 degrees C and 100 degrees C and a cytotonic activity were demonstrated in Vero cell cultures. Survival assay of A. hydrophila and indicator organisms would show no correlation between their contamination sources. Biofilms production could explain the persistence of this gram negative pathogen organism in chlorinated tap water. A water system supply maintenance program and pasteurisation may be performed in spite of water chlorination.

Stability of pilocarpine ophthalmic solutions.

The stability of pilocarpine and pilocarpine-timolol eyedrop preparations available on the Argentine market was studied. A high-performance liquid chromatographic method that allows the estimation of pilocarpine in the presence of degradation products was used for the study according to the preestablished design. It was found that pilocarpine solutions are stable, while pilocarpine in association with timolol shows significant degradation.

Search for related substances in market products containing enalapril maleate as the active principle.

This study's main object was the determination of substances, by means of high-performance liquid chromatography (HPLC), that are related to enalapril maleate in medicinal tablets. The research was on products containing a 20 mg active principle with a 12-month delta t and on those batches near their expiration date with an enalapril maleate concentration of 10, 5, and 2.5 mg.

[Recombinant human erythropoietin: method of in vivo evaluation using normocythemic mice]. / Eritropoyetina recombinante humana: Método de valoración in vivo con ratones normocitémicos.

PURPOSE: The implementation of an in vivo assay to determine the biological activity of human recombinant erythropoietin (Hu-r EPO) is essential. The purpose of this study was to perform and optimize the conditions of an easy in vivo bioassay suitable for routine testing of quality control of Hu-r EPO preparations. MATERIAL AND METHODS: Normocythemic 8 weeks female mice treated with different Hu-r EPO doses were employed. The reticulocyte response was measured by flow cytometry and by visual count in a Neubauer cell count chamber, after selective red blood cell haemolysis. A unique subcutaneous injection with blood extraction 96 hours later was the schedule employed. The reticulocyte count measured by both methods was plotted against the log dose of Hu-r EPO. RESULTS: The dose-response curve obtained was linear between 5 and 160 UI/mouse and the doses chosen for future assays were 10, 30 and 90 UI/mouse. The use of at least 6 animals per dose and not less than 3 assays to obtain reliable limits according to international regulations is convenient. Thirty assays were performed in four different samples and were analyzed by parallel lines (3 + 3) relating the response with the log dose. The coefficient of correlation between both methods was 0.989, so they are equivalent. CONCLUSIONS: This method is suitable because fewer animals and bioassays are necessary to obtain fiducial limits according to international requirements. It is in agreement with the tendency to reduce the number of animals used for bioassay because ethical and economic reasons.

Preparation of norfloxacin spherical agglomerates using the ammonia diffusion system.

Agglomerated crystals of norfloxacin were prepared by a spherical crystallization technique using the ammonia diffusion system (ADS). This technique makes it possible to agglomerate amphoteric drugs like norfloxacin, which cannot be agglomerated by conventional procedures. When an ammonia-water solution of norfloxacin is poured into an acetone dichloromethane mixture under agitation, a small amount of ammonia is liberated in the system. The ammonia-water solution plays a role both as a good solvent for norfloxacin and as a bridging liquid, allowing the crystals' collection to take place in one step. It has been proven that the agglomeration mechanism follows three steps: first acetone enters into the droplets of ammonia-water (this emulsion is formed because of the system characteristics); dissolved norfloxacin is consequently precipitated while the droplets collect the crystals; simultaneously, a part of the ammonia contained in the agglomerates diffuses to the outer organic solvent phase, thereby forming the norfloxacin spherical agglomerates. The correct selection of solvents has enabled us to obtain a suitable stable crystalline shape.

Fungal and aflatoxin contamination of medicinal herbs.

Since the consumption of aromatic and medicinal herbs has been increasing in the last years, the Argentinian Health Authorities are concerned to control the quality and security of them. Fungal and aflatoxin contamination are two parameters to be taken into account, to ensure the harmlessness of the phytomedicinal products. In 81 different samples, grouped in end products (EP), raw material (RM) and at harvest (SH), fungal flora (enumeration and identification) as well as naturalAspergillus flavus and aflatoxin occurrence were investigated. In all samples fungal counts fulfilled the international general recommendation limits (maximum 10(5) cfu/g). Predominant flora was made up by xerophilic species ofAspergillus(100%), byPeniciIlium (< 50%) and in less percentage byFusarium (5.6%). Among the Aspergilli, A.flavus was present in all the three groups of samples. Using a TLC method, 47% of A. flavus isolates were toxinogenic, producing aflatoxin B1 and B2. In herbs, 4.7% of RM samples were naturally contaminated with aflatoxins B1 and B2. Considering the carcinogenic activity of aflatoxins it is essential to regulate them in the raw material (vegetal drug).

Sanitary factors and mycotoxin contamination in the argentinian wheat crop 1993/94.

In Argentina, due to climatic conditions, Fusarium head blight (FHB) caused by Fusarium graminearum, affected the 1993/94 wheat crop. To evaluate the severity of this disease, samples of wheat where gathered from four zones of the wheat area. Sanitary conditions and mycotoxin contamination were determined. One zone (IIN) was intensely affected by FHB with 90% of samples in grade III (bad quality). No samples were grade I (good quality). The other zones were less affected falling into grade I or II (moderate quality). In all samples tested F. graminearum was the most prevalent species singly or in combination with others. Zone II N, with a DON mean level of I1.26 ppm, did not fulfil aceptability limits, whereas zones IIS, III and IV with overall means of 2.12, 1.57 and 1.0 ppm, respectively, did. Statistical analysis showed a close relation between percentage FHB and DON contamination (r:-0.71, p<0.01) in infected samples.