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Biomedical subjects

A Mariscal

Publications and source records attributed to A Mariscal.

18 recordsLinked to original sources
PubMed1999

Development and testing of a microbiological assay to detect residual effects of disinfectant on hard surfaces.

We describe a glucuronidase bioassay for detecting residual bactericidal activity from the use of disinfectants on hard surfaces; in this assay we used formaldehyde, ethanol, isopropanol, chlorine, and a commercial preparation containing 2-bromo-2-nitro-1, 3-propanediol. Chlorine and the commercial preparation showed bactericidal activity (53.5% and 98.2%, respectively) for a week after disinfection.

2-Propanol↗
PubMed1998

Interference by carbohydrate substrates, flavonoids, and monosaccharide derivatives on bacterial beta-D-glucuronidase assays.

Most commercially available test kits for water and foodstuffs use beta-galactosidase activity for coliforms and beta-glucuronidase activity for Escherichia coli. We tested the effects on the beta-glucuronidase activity of E. coli W3110 of substances usually present in foods and several synthetic pharmaceutical compounds. Thirteen substances were tested: three carbohydrates, four flavonoids, five monosaccharide derivatives, and dimethyl sulphoxide. In a minimum medium without any other carbon source, glucose (0.1 mM), quercetin (0.1 mM), silymarin (10 mg/L), D-gluconic acid (0.01 mM), D-gluconic acid lactone (0.01 mM), isopropyl-beta-D-thiogalacto pyranoside (1 mM), p-nitrophenyl beta-D-glucuronide (1 mM), and DMSO (1 M) completely inhibited E. coli glucuronidase activity at the above concentrations. However, the following compounds stimulated E. coli glucuronidase activity within the ranges of concentrations shown: glucose (0.0001-0.01 mM), lactose and sucrose (>0.1 mM), D-saccharic acid 1,4 lactone (0.0001-0.1 mM), p-nitrophenyl beta-D-glucuronide (0.001-0.01 mM) and DMSO (2-500 mM). In a rich culture medium that contained other carbon sources (lauryl tryptose broth) E. coli glucuronidase activity in the presence of the extra nutrients was unaffected by the test substances and therefore, under normal conditions in water or foods, they should not interfere with E. coli assays based on measurements of beta-glucuronidase activity.

Biological Assay↗
PubMed1997

A trial to compare the effects of pH, buffer concentration, and NaCl, on one fluorescent and two bioluminescent bacterial tests for acute toxicity.

Of all the bioassays to determine acute toxicity described in the literature, those that employ bacteria as indicator organisms are usually the most rapid and the most economic, although alone they cannot predict the possible toxic effect of any type of substance. When bioassays are employed to test the toxicity of known substances and of compounds in samples from waste discharges they have to work in very different conditions from those for which they are designed. The effects of three factors, pH, buffer concentration, and NaCl, on the performance of a fluorogenic bioassay based on the beta-glucuronidase activity of Escherichia coli were investigated. The results of this test were compared with those of two known biluminescent bacteria tests. The fluorogenic bioassay has a more restricted optimum pH range, while the influence of buffer concentration was similar for the three tests. E. coli glucuronidase activity was affected at a concentration as low as 128 mg/l of NaCl. Changes in the pH or buffer concentrations or chloride ions, greatly influenced the respectives toxicities of four substances, acridine orange, TEMED, 2-mercaptoethanol, and mercuric chloride.

Acridine Orange↗
PubMed1994

New toxicity determination method that uses fluorescent assay of Escherichia coli.

We describe a new method that uses a fluorogenic bioassay of the beta-glucuronidase conversion of 4-methylumbelliferyl beta-D-glucuronide (MUG) to 4-methylumbelliferone to evaluate the individual toxic effects on Escherichia coli of Al3+, Cr6+, Hg2+ and Li+. This work was designed to examine the effectiveness of this method to measure the effects of five ionic concentrations of either Al3+, Cr6+, Hg2+ or Li+, on the growth of E. coli in a minimal medium that had MUG as the only source of carbon. This method was simple and fast, and its toxicity detection sensitivity was equal to, or greater than, existing bacterial bioassays. The use of the MUG substrate minimized the danger of interference by bacteria other than E. coli. Evaluations of toxicity in samples of public drinking water proved equally sensitive.

Aluminum↗
PubMed1992

Juvenile xanthogranuloma with extracutaneous lesions.

The purpose of this article is to present a case of juvenile xanthogranuloma with pulmonary, retroperitoneal and splenic involvement. The similar echographic pattern of the cutaneous and visceral lesions was very helpful in order to suggest the correct diagnosis.

Abdomen↗
PubMed1991

[Cerebral tuberculoma. Report of 8 cases].

A series of eight patients with cerebral tuberculoma seen between 1980 and 1990 is reported. Headache was the leading clinical finding, followed by focal neurological findings and seizures. Papilledema was the most uniform examination finding associated with intracranial hypertension. Five patients had another localization of tuberculosis: three had tuberculous meningitis, one had tuberculous pericarditis and only one had associated active pulmonary involvement. Cerebrospinal fluid was investigated in seven patients. In three patients data of tuberculous meningitis were found, with positive culture in Löwenstein medium. Two patients had the acquired immunodeficiency syndrome. All patients received medical treatment with good response, except in one who developed paradoxical expansion of the lesions after two months of therapy.

Adult↗
PubMed1991

Effect of penicillin and chloramphenicol on the growth and endotoxin release by N. meningitidis.

The action of two antibiotics, penicillin and chloramphenicol, on bacterial growth and endotoxin liberation was studied in 18 strains of Neissevia meningitidis isolated from blood and CSF of patients with meningococcal infections. The antibiotics were administered both separately and in combined form in doses equivalent to 1 MIC and 100 MIC. Penicillin was found to produce a faster and more intense bactericidal effect than chloramphenicol during the first hour, whereas at 12 h these differences were not significant. This could explain the initial worsening observed in some infected patients when large doses of penicillin are administered. An increased liberation of endotoxin after adding penicillin was observed in six of the strains studied, whereas the remaining 12 did not show significant increases. The six strains (belonging to serogroup B) were known to have an enhanced capacity for spontaneous endotoxin liberation.

Chloramphenicol↗
PubMed1989

The effect of 2,4-dichlorophenol on growth and plasmidic beta-lactamase activity in Escherichia coli.

The toxic effects of 2,4-dichlorophenol on two strains of Escherichia coli harbouring plasmids with beta-lactamase activity were studied. The toxicant had a significant effect on growth at concentrations of 12 micrograms ml-1 for the JA 221 (pBR322) strain, as well as at 24 micrograms ml-1 for the J5-3 (RP4) strain. beta-Lactamase production was affected at concentrations of 96 micrograms ml-1 in both strains. However, beta-lactamase production does not seem to constitute a reliable toxicity test in view of its variability and relatively low sensitivity.

Chlorophenols↗
PubMedDate not supplied

Evaluation of the toxicity of several heavy metals by a fluorescent bacterial bioassay.

This new bioassay determined the toxicity of chemical compounds dissolved in water by measuring the degree of inhibition of the ultraviolet light-stimulated fluorescence of Escherichia coli in a culture medium in which 4-methylumbelliferyl beta-D-glucuronide was the only carbon source. Inhibition produced by one of five heavy-metal salts (Cd2+, Cr6+, Hg2+, Pb2+ or Zn2+) was the end-point and comparison standard to determine the EC50 and minimum effective concentration (MEC) that produced a decrease of E. coli growth rate, increased doubling time and percentage inhibition and reduced numbers of generations; all these values were derived from the fluorescence signals. Only Cr6+ and Hg2+ at two concentrations (0.25 and 0.5 mg l-1) almost completely inhibited this E. coli strain. All toxicant concentrations tested produced at least partial inhibitions of growth; Cr6+, Hg2+ and Cd2+, in that order, were most toxic, and Pb2+ the least. Zn2+ gave higher EC50 values at 3 h of incubation than at 4 h. The method was simple, rapid and inexpensive and would permit a large number of samples to be tested quickly.

Biological Assay↗
PubMedDate not supplied

Xanthogranulomatous cholecystitis: a radiological study of 12 cases and a review of the literature.

BACKGROUND: Twelve cases of xanthogranulomatous cholecystitis (XGC) are presented, and their radiologic appearance is described. METHODS: Four men and eight women, aged 31-82 years old, with XGC were reviewed. Abdominal ultrasound (US) was performed in all patients. Computed tomography (CT) was performed in five patients, barium enema examination in two, and percutaneously CT-guided fine-needle aspirative biopsy of the gallbladder in one. RESULTS: Barium enema examination showed an indentation of the hepatic flexure. Cholelithiasis was present in all patients, and sludge was present in six. The gallbladder wall was thickened in all patients, irregular in nine, and could not be properly differentiated from surrounding liver parenchyma or from other adjacent structures in most patients. A curvilinear halo, hypoechoic on US and with low attenuation on CT, within the gallbladder wall was found in three patients and pericholecystic fluid in two others. On CT, the pericholecystic fat had streaky soft tissue densities in three cases. Percutaneously CT-guided fine-needle aspirative biopsy of the gallbladder was nondiagnostic. The diagnosis of gallbladder carcinoma was considered preoperatively in three patients. CONCLUSION: Despite the characteristic histologic appearance of XCG, radiologic findings are nonspecific, varying from signs observed in other forms of cholecystitis to the appearance of a gallbladder neoplasm.

Adipose Tissue↗
PubMedDate not supplied

Scrotal cystocele: US and CT findings in two cases.

Massive inguinoscrotal herniation of the bladder (i.e. scrotal cystocele) is very uncommon. We describe the ultrasonography and computed tomography features of scrotal cystocele in two patients, and review the radiologic findings of this rare entity reported in the literature.

Aged↗