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Biomedical subjects

R Villa

Publications and source records attributed to R Villa.

At least 55 records · Page 3Linked to original sources
PubMed1997

The synthesis of (R)-(+)-lipoic acid using a monooxygenase-catalysed biotransformation as the key step.

2-(2-Acetoxyethyl)cyclohexanone (4) was converted into the lactone (-)-(5) regio- and enantioselectively using 2-oxo-delta 3-4,5,5-trimethylcyclopentenyl acetyl-CoA monooxygenase, an NADPH-dependent Baeyer-Villiger monooxygenase from camphor grown Pseudomonas putida NCIMB 10007. The lactone (-)-(5) was converted into (R)-(+)-lipoic acid in six steps. In contrast cyclopentanone monooxygenase, an NADPH-dependent Baeyer-Villiger monooxygenase from cyclopentanol-grown Pseudomonas sp. NCIMB 9872 selectively oxidized the (S)-enantiomer of the ketone (4) giving better access to optically enriched, naturally occurring lipoic acid.

Biotransformation↗
PubMed1997

Intramuscular bioavailability of ketoprofen lysine salt in horses.

Lysine salts are often used in human pharmaceuticals to increase the solubility and absorption of acidic drugs when these are administered parenterally. In this study the intramuscular bioavailability of ketoprofen administered as the lysine salt was evaluated in horses (n = 5) treated intravenously and intramuscularly (2.2 mg/kg active substance) in a cross-over study. The absorption rate of ketoprofen administered as the lysine salt was rather low: the mean residence time increased from 31.7 min after IV injection to 128.9 min (after IM injection), and the bioavailability was high (mean 92.4%). The calculated steady state plasma concentrations of ketoprofen during multiple dosage were much higher after intramuscular (0.106 g/ml) than after intravenous (0.066 microgram/ml) administration. Intramuscular injections of the ketoprofen lysine salt can therefore be given to horses, which are particularly prone to develop soft tissue reactions, since use of the lysine salt markedly reduced local irritation at the injection site.

Animals↗
PubMed1997

Modulation of melphalan and cisplatin cytotoxicity in human ovarian cancer cells resistant to alkylating drugs.

We investigated the effect of pharmacological modulators on the cytotoxic activity of melphalan and cisplatin in human ovarian cystadenocarcinoma cells sensitive (OAW42) or resistant (OAW42MER) to bifunctional alkylating agents. By filter elution experiments we observed a reduced accumulation and a faster repair of melphalan-induced DNA interstrand cross-links in the OAW42MER resistant cells than in the OAW42 parental, sensitive cells. Moreover, resistant cells were characterized by an increased level of mRNA encoding enzymes involved in the nucleotide excision repair pathway, such as ERCC (excision repair cross complementing)1 and ERCC2. Among the modulators used, the topoisomerase I inhibitor topotecan was able to increase melphalan cytotoxic activity in sensitive and resistant cell lines. Topotecan also positively modulated cisplatin activity, although to a variable extent in the two cell lines, as a function of treatment schedule. The energolytic compound lonidamine markedly enhanced the cytotoxicity of melphalan and cisplatin, with a potentiating effect in the OAW42MER resistant cells almost 2-fold that of in the OAW42 sensitive cells. No significant potentiation was observed by using calcium channel blockers, such as verapamil and nimodipine. Conversely, an increase in melphalan cytotoxic activity was determined by flunarizine in OAW42MER resistant cells and, to a lesser extent, in OAW42 sensitive cells. However, the calcium blocker failed to modulate cisplatin activity in both cell lines.

Antineoplastic Agents↗
PubMed1996

Genomic organization of the human NTRK1 gene.

The NTRK1 gene encodes one of the receptors for the Nerve Growth Factors and it is located at 1q21-22. Rearrangements of NTRK1 are frequently detected in human papillary thyroid carcinoma and lead to the formation of chimeric oncogenes, similarly to what observed for the other neurotrophin receptor RET. In addition, the two receptor genes are target of point mutations associated with different human diseases. RET is affected by germ line and somatic mutations in MEN2A, MEN2B tumor syndromes and in the abnormal developmental Hirschsprung disease, whereas mutations of NTRK1 have been reported very recently in patients with congenital insensitivity to pain with anidrosis (CIPA). With the aim to provide a tool for searching mutations along the whole NTRK1 gene, we have determined its genomic organization. Our results demonstrated that NTRK1 is contained within 25 Kb of DNA and is organized in 17 exons, one of which is alternatively spliced. The sequence of the 5' flanking region indicates a high content in C/G, the absence of TATA box, the presence of several putative binding sites for Sp1, AP1, AP2, AP3, ATF and GCF transcription factors.

Alternative Splicing↗
PubMed1996

Effect of ionizing radiation on cell-cycle progression and cyclin B1 expression in human melanoma cells.

In the present study we investigated the effect of gamma-irradiation (2.5 and 10 Gy) on cell-cycle progression of a human melanoma cell line, M14, characterized by a moderate radiosensitivity (SF2 = O.5). Flow cytometric analysis showed a dose-dependent S-phase accumulation, which was detectable 8 hr after treatment with 2 and 5 Gy and was still persistent at 12 hr after 10 Gy exposure. Such a delay in S-phase was paralleled or followed by an accumulation of cells in G2M, which was transient at the lowest radiation doses and still persistent at 72 hr after 10 Gy. Such an accumulation was, at least in part, due to a block in G2-M transition, as demonstrated by mitotic index analysis. Bivariate flow cytometric analysis of DNA content and cyclin B1 expression showed that, following 2 and 5 Gy, the fraction of cyclin B1-expressing cells was superimposable upon that of G2M cells. Conversely, in cells treated with 10 Gy, the fraction of cyclin B1-expressing cells was half the G2M cell fraction. Northern-blot analysis indicated that the radiation-induced decrease in cyclin B1 protein expression was accompanied by a reduced cyclin B mRNA level. On the whole, our results indicate a direct inhibitory effect of 10 Gy irradiation on cyclin B1 expression as a possible cause for the persistent G2 block in irradiated M14 cells.

Cell Cycle↗
PubMed1996

Pharmacokinetics and dosing regimen of aminosidine in the dog.

The kinetic behaviour of the aminoglycoside aminosidine, given at 15 mg/kg intravenously, intramuscularly and subcutaneously, was studied in 5 dogs to determine the appropriate dosage schedule. The pharmacokinetic behaviour of aminosidine in dogs was similar to that in other species, except that it was eliminated more slowly (beta = 0.007 +/- 0.0003 min-1). Intramuscular and subcutaneous administration produced peak serum concentrations (Cmax[im] = 32 +/- 6.4 micrograms/ml; Cmax[ac] = 36 +/- 3.4 micrograms/ml) and times to peak concentration (Tmax = 60 min for both) that did not differ significantly; and neither compartmental nor non-compartmental analysis revealed any significant differences between any of the kinetic parameters obtained for these two extravenous routes of administration. Comparison of these results with previously published data suggests that aminosidine given once daily at 15 mg/kg would be as effective all, and safer than, the two or three daily administrations commonly employed in dogs.

Absorption↗
PubMed1996

Effect of natural fermentation on the content of inositol phosphates in lentils.

The effects of natural fermentation upon phytic acid and less phosphorylated inositol phosphates of Lens culinaris var vulgaris cultivar Magda-20 were investigated. Seven fermentation runs were made following a 2(2) complete factorial design with three replicated centre points to study the effect of different conditions of temperature (28, 35 and 42 degrees C) and broth concentration (79, 150 and 221 g/l). Samples were taken for each of them at daily intervals (0, 24, 48, 72 and 96 h). The pH value declined sharply in the first 24 h of fermentation, becoming stabilized from this time. The relation between lactic acid and titratable acidity presented important differences between the different fermentations, ranging from 30-80%. Phytic acid (IP6), inositol pentakis (IP5), tetrakis (IP4) and tris-(IP3) phosphates were quantitatively determined. The content of total inositol phosphates showed a maximum reduction of 63% at 72 h under the fermentation conditions of 42 degrees C and 79 g/l.

Chromatography, High Pressure Liquid↗
PubMed1995

Natural fermentation of lentils. Influence of time, concentration and temperature on protein content, trypsin inhibitor activity and phenolic compound content.

Lentil (Lens culinaris var. vulgaris) flour was naturally fermented for 4 days at different temperatures (28 degrees C, 35 degrees C and 42 degrees C) and concentrations (79 milligrams, 150 milligrams and 221 milligrams). Samples were analysed to establish the changes of total protein content and in vitro protein digestibility, trypsin inhibitor activity (TIA) and phenolic compound content during natural fermentation of lentils. The preparation of lentil flour suspensions to be fermented caused a slight increase in total protein and in vitro protein digestibility content, a decrease of TIA and a sharp decrease the tannin/catechin ratio. During the whole fermentation procedure, the minimum initial lentil concentration and temperature used (79 milligrams, 28 degrees C) achieved the maximum protein content and the lowest tannin/catechin ratio. The TIA was more affected by temperature than by concentration, and a 62.5% reduction was observed at 42 degrees C and 79 milligrams.

Catechin↗
PubMed1995

Maternal serum alpha-fetoprotein screening for neural tube defects. Report of a program with more than 30000 screened pregnancies.

Maternal serum alphafetoprotein (MSAFP) screening has been set up in Asturias, in the north of Spain, in 1987 in order to make possible the prenatal diagnosis of neural tube defects (NTD) to overall pregnancy population. This large study shows the high sensitivity and specificity of MSAFP screening when it is done with absolute control of all variables such as gestational age, pregnant woman's weight, diabetes, etc. On the other hand, this study also shows a poor sensitivity second level ultrasound for the early diagnosis of NTD in the presence of spina bifidas with no bulge. We have also observed that the incidence of NTD in Asturias remained constant in the last six years, around 1.5-1.6 per 1000 pregnancies. However, due to MSAFP screening, there has been a decline in the prevalence of children born with these defects. We conclude that MSAFP screening is the best tool to identify and reduce NTD in our Region (Spain).

Female↗
PubMed1995

Community-acquired pneumonia: is there difference in etiology between hospitalized and out-patients?

Since March 1991 a prospective 1-year study of patients with community-acquired, radiologically verified, pneumonia (CAP) was performed at the Divisione Pneumologica, Ospedali Riuniti Bergamo, and at the Centro Pneumo-Allergologico, Bergamo, Italy. The study included 119 out-patients and 60 in-patients, with a median age of 37.4 and 49.8 years respectively. There were not statistically significant differences between the patients included with respect to the various months. The most common underlying illnesses were: chronic obstructive pulmonary disease (20.7%), diabetes (7.3%) and malignancy (3.4%). We found a quite different etiology of CAP between out- and in-patients. By far the most common etiologic agent in out-patients was Mycoplasma pneumoniae (32.8%), while in in-patients was Legionella pneumophila (11.7%). 5 patients had a double infection. There were no distinctive clinical and radiological features found to be diagnostic for any etiologic agent. Hospital stay averaged 12.1 days. 35% of the patients included in the study were been treated by beta-lactam, often parenterally, nevertheless 88 pathogens of the 100 identified were resistant to this antimicrobial therapy. We believe that there should always be a macrolide, erythromycin or the latest ones such as azythromycin, in the treatment of CAP, owing to their efficiency, ease of use and lower cost.

Adult↗
PubMed1994

Bronchoalveolar lavage and its role in diagnosing cobalt lung disease.

The bronchoalveolar lavage (BAL) of two groups of hard metal workers (11 subjects) were examined and compared with BALs of 14 unexposed individuals as controls. The first group of workers included five asymptomatic subjects (2 females and 3 males) with normal lung function tests and chest X-rays. All the workers had been exposed daily to hard metal dust for 5 years before fiberoptic bronchoscopy. The second group of workers included six individuals (1 female and 5 males) with cobalt lung disease at biopsy. The BAL's cytology at the deep lung level is in agreement with a possible immunologic pathogenesis of the lung disease, similar to hypersensitivity pneumonitis (lymphocytosis with helper-suppressor ratio reduction). In order to identify diagnostic key-parameters, the data presented here are compared with data reported in literature for workers with a history of hard metal or cobalt (alone) exposure. Although the BAL can be useful, for a better definition of the reaction at the deep lung level, it seems insufficient per se for the diagnosis of hard metal lung disease.

Adult↗
PubMed1994

Expression of P-glycoprotein and in vitro or in vivo resistance to doxorubicin and cisplatin in breast and ovarian cancers.

The expression of P-glycoprotein (P-gp) was studied by immunocytohistochemistry, using the C219 monoclonal antibody, in 39 locally advanced breast cancers and 20 ovarian cancers from previously untreated patients. P-gp was expressed in 46 and 35% of breast and ovarian tumours, respectively. A significant association was observed in both tumour types between P-gp expression and in vitro resistance to doxorubicin. We also observed a higher clinical response rate to doxorubicin +/- vincristine in patients with breast cancers not expressing P-gp. Conversely, no correlation was found between P-gp expression and in vitro resistance to cisplatin or in vivo response to cisplatin +/- cyclophosphamide treatment in ovarian cancers. Our results support the relevance of P-gp expression as a specific indicator of resistance to certain drugs, such as doxorubicin and vincristine, involved in the phenomenon of multidrug resistance in breast and ovarian cancer cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

In vitro effect of lonidamine on the cytotoxicity of mitomycin C and BCNU in human colon adenocarcinoma cells.

The ability of lonidamine (LND), an energolytic derivative of indazole carboxylic acid, to modulate the cytotoxic activity of mitomycin C (MMC) and 1,3,bis(2-chloroethyl)-1-nitrosourea (BCNU) was investigated in two human adenocarcinoma cell lines (LoVo and HT29) expressing different sensitivity profiles to the drugs. After a 1-h treatment with MMC or BCNU, cells were postincubated for 24 h with 150-225 microM LND. In the LoVo cells, a synergistic interaction between LND and MMC or BCNU was observed at both LND concentrations. In HT29 cells, only additive effects of the drugs given in sequence were seen. Flow cytometric analysis indicated that LND was generally able to stabilise the cell cycle perturbations induced by MMC and BCNU in the two cell lines. The ability of LND to potentiate anticancer drug activity, and the consideration that LND causes side-effects different from those of conventional antitumour drugs, make this compound an attractive candidate for multidrug combination therapy in colon cancer.

Adenocarcinoma↗
PubMed1994

Lack of a correlation between micronucleus formation and radiosensitivity in established and primary cultures of human tumours.

The radiation-induced genotoxic damage in three established cell lines and 15 primary cultures of human malignant melanoma and ovarian carcinoma showing different radiosensitivity was tested by the cytokinesis-block micronucleus assay. A dose-related increase in micronucleus frequency was observed in all the cell systems. The mean number of micronuclei per Gy of ionising radiation per binucleated cell was respectively 0.44 +/- 0.0075 and 0.43 +/- 0.04 for M14 and JR8 malignant melanoma cell lines and 0.19 +/- 0.013 for the A2780 ovarian cancer cell line. The number of micronuclei did not rank the cell lines in the same order of radiosensitivity as clonogenic cell survival, which showed a surviving fraction at 2 Gy of 0.38 +/- 0.02 for JR8, 0.34 +/- 0.05 for M14 and 0.22 +/- 0.007 for A2780. As regards primary tumour cultures, no correlation was observed between micronucleus induction and surviving fraction at 2 Gy. In conclusion, the discrepancy we observed between micronucleus formation and cell death raises doubts about the potential of the micronucleus assay as a preclinical means to predict radiosensitivity.

Carcinoma↗
PubMed1994

DNA double-strand break repair and radiation response in human tumour primary cultures.

The accumulation and repair of radiation-induced DNA double-strand breaks (dsbs) were determined by neutral filter elution on 20 primary cultures obtained from ovarian cancer and malignant melanoma clinical specimens. The initial frequency of DNA dsbs after exposure to 50 Gy gamma-irradiation varied greatly for the individual cultures. However, melanomas were generally more efficient than ovarian cancers in repairing these DNA lesions (mean percentage of DNA dsb rejoined after 2 h: 83 versus 62%). In 13 of 20 cultures radiosensitivity was also assessed by the Courtenay clonogenic assay. The mean +/- SD of the surviving fraction at 2 Gy (SF2) was slightly higher for melanomas (0.56 +/- 0.25) than for ovarian carcinomas (0.43 +/- 0.23). No correlation was observed between SF2 and in vitro plating efficiencies or any biological characteristics of the tumour cell population, such as proliferative activity and DNA ploidy. Similarly, we failed to find any relation between the initial frequencies of DNA dsbs and SF2 in individual tumours. In contrast, a significant and direct relationship (r = 0.86, p < 0.01) was observed between SF2 and the percentages of DNA dsbs rejoined 2 h after irradiation. In agreement with reported data on human tumour established cell lines, our results indicate that the ability to repair DNA dsbs is an important determinant for radiation response even in primary cultures of clinical tumours.

DNA↗
PubMed1994

Comparative pharmacokinetics of ampicillin-sulbactam combination in calves and sheep.

The pharmacokinetics of ampicillin and sulbactam administered in combination were studied in calves and sheep. The animals were administered an aqueous solution of ampicillin/sulbactam (2:1, w/w) intravenously and intramuscularly at doses of 13.2 and 6.6 mg.kg-1, respectively. A microbiological method was used to detect ampicillin, and HPLC was used to detect sulbactam in serum. Following intravenous (i.v.) administration, the distribution phases were rapid and similar (about 15 min) for both drugs in both species, whereas sulbactam in calves and ampicillin in sheep showed a faster elimination rate. After intramuscular (i.m.) administration both drugs showed peak concentrations higher in calves than in sheep; the peak time of sulbactam was shorter in calves than in sheep. No other significant differences in the pharmacokinetics of the combination were observed between the species after i.m. injection. The mean residence and absorption times, calculated by non-compartmental analysis, for both calves and sheep suggested that the differences in ampicillin and sulbactam pharmacokinetics could be attributable to the different molecular structures.

Absorption↗
PubMed1994

Primary mediastinal seminoma.

We describe three cases of primary mediastinal seminoma, a rare neoplasm histologically similar to the testicular form, which mainly affects men between 30-60 yrs of age. Case No. 1--a 45 year old patient was treated with a combination of radiotherapy and chemotherapy. Twenty six months after the diagnosis, the patient shows a limited residual lesion, a good general health status and was asymptomatic. Case No. 2--a 56 year old patient was admitted for suspected epithelial lung cancer, with subsequent histological diagnosis of seminoma on surgical sample. The exeresis of the lesion was followed by radiotherapy and chemotherapy, the latter interrupted owing to the onset of thrombotic complications resulting in the patient's death. Case No. 3--a 35 year old patient was subjected to diagnostic and therapeutic thoracotomy, with diagnosis of primary mediastinal seminoma. The surgical therapy was followed by a cycle of radiotherapy. Five years later, the general health of the patient is good and he is still asymptomatic. In the discussion we consider the embryogenesis, clinical picture, radiological and anatomicopathological aspects, typical biomarkers of cancer, diagnostic procedures and therapeutic protocols currently followed.

Adult↗