Biomedical subjects

A Romero

Publications and source records attributed to A Romero.

At least 145 records · Page 8Linked to original sources

PubMed1993

X-ray analysis and spectroscopic characterization of M121Q azurin. A copper site model for stellacyanin.

The dependence of the properties of the azurin blue copper site on the nature of the axial ligand at position 121 was tested by site-directed mutagenesis. This residue was substituted for a glutamine, the purported fourth copper ligand in the related protein stellacyanin. M121Q azurin was isolated and purified from Escherichia coli and characterized by spectroscopic methods. The mutant copper site has the ultra-violet-vis and electron paramagnetic resonance (EPR) characteristics of a type I site, but the spectroscopic details differ significantly from wild-type (wt) azurin. The X and S-band EPR spectra of M121Q azurin can be well stimulated with the parameters for stellacyanin, indicating that the copper sites of both proteins in the oxidized state are similar. The midpoint potential of M121Q is 263 mV, 25 mV lower than for wt azurin. The reactivity of the mutant was probed by measuring the electron self exchange rate by nuclear magnetic resonance spectroscopy. The rate was 8 x 10(3) mol-1 s-1, almost two orders of magnitude lower than the value for wt azurin (5 x 10(5) mol-1 s-1). Detailed structural information on the M121Q Cu(II)-site was obtained by X-ray analysis of M121Q azurin crystals at 1.9 A resolution. The histidine and cysteine copper ligand distances and angles in the equatorial plane around the copper are very similar to the wt protein. Gln121 is co-ordinated in a monodentate fashion via its side-chain oxygen atom at a distance of 2.26 A. The distance between copper and the carbonyl group of Gly45 is increased from 3.13 A (wt) to 3.37 A resulting in a distorted tetrahedral N2SO copper co-ordination. The possible significance of these results for the structure of the copper site of stellacyanin, the only small blue copper protein lacking a methionine ligand, is discussed. Conformational changes with respect to the wt azurin are seen in some of the connecting loops between secondary structure elements, in the mutation site and in the beta-strand 2a. The side-chains involved in the hydrophobic patch surrounding His117 are subject to large changes in their conformations. In contrast to wt azurin, the copper site in M121Q azurin undergoes significant structural changes on reduction.(ABSTRACT TRUNCATED AT 400 WORDS)

Alcaligenes↗

PubMed1993

Adaptation of the meconium drug test for mass screening.

For purposes of mass drug screening, the procedure for analysis of meconium for drugs was modified into a one-step extraction and analysis by enzyme immunoassay. The accuracy of this modified method was tested by comparing the results of simultaneous analysis of 61 meconium samples for cocaine opiate and cannabinoid metabolites by both the original and the modified methods. In 61 samples analyzed, opiate was detected in 8 (13%) samples by the original method and in 9 (15%) by the modified method; cocaine was detected in 39 (64%) samples by the original method and in 39 (64%) by the modified method. The concordance between the negative and positive results of the modified versus the original methods was 98% and 100%, respectively, for opiate and 95% and 98%, respectively, for cocaine. Only one sample was positive for cannabinoid. Thus a comparison of positive results for cannabinoid was not done; however, all the negative results obtained by the modified method were confirmed by the original method. The clinical experience of mass meconium drug testing using the modified method in 1991 is also reported. In four centers tested (total tests = 4409), the prevalence of presence of drug was consistent with the high- or low-risk status of the population. This simplified, rapid procedure can be performed in most clinical laboratories. This adaptation has made the meconium drug test feasible for large-scale clinical and research use.

Cannabinoids↗

PubMed1993

Metastatic pattern and DNA ploidy in stage IV breast cancer at initial diagnosis. Relation to response and survival.

Sixty-nine patients with metastatic breast cancer (MBC) at initial diagnosis were analyzed to verify if metastatic pattern and clinical outcome are related to DNA ploidy determined by flow cytometry (FCM). Characteristics of 55 fully evaluable patients were as follows: median age: 61 years; postmenopausal: 75%; bone-only metastases (BM): 60%; extraosseous-only metastases (EM): 40%. Overall response rates (CR + PR) obtained with different chemotherapies and/or hormonal therapies were 58% and 68% for patients with BM and EM, respectively. Sixty percent of specimens resulted aneuploid, and the mean coefficient of variation of the complete series was 5.1%. In the whole group of patients DNA ploidy of primary tumor did not predict the metastatic pattern and had no influence upon response to treatment, duration of response, time to progression, and overall survival. When analyses were carried out according to metastatic pattern, those patients with BM showed similar results. However, within the group with EM, those with diploid tumors presented a significantly better survival (median 18 vs 13 months, p = .04). FCM-DNA analysis seems to identify a subgroup of patients with poor prognosis constituted by those who had aneuploid primary tumors and metastases to extraosseous sites.

Adenocarcinoma↗

PubMed1993

Effect of transferrin concentration on bacterial growth in human ascitic fluid from cirrhotic and neoplastic patients.

Cirrhotic patients with ascites have an unusually high frequency of development of spontaneous bacterial peritonitis. Iron availability is a key factor in bacterial growth and the ability of the host to limit it is associated with resistance to infection. The present study was undertaken to evaluate the influence of iron and transferrin on bacterial growth in ascitic fluid from 25 biopsy-proven cirrhotic and nine neoplastic carcinomatous patients. No significant differences were found when comparing total ascitic fluid iron between the two groups but ascitic fluid transferrin concentration was significantly lower in cirrhotic (29.26 mg dl-1 SD 29.58) than neoplastic (96.57 mg dl-1 SD 76.01) patients. Moreover, a significant negative correlation was found between bacterial growth and transferrin concentration in ascitic fluid (P = 0.039). When the iron concentration in ascitic fluid was experimentally elevated (50 micrograms dl-1 or 150 micrograms dl-1) we observed a progressive increase in bacterial growth. If transferrin concentration is simultaneously elevated (250 mg dl-1) this increase does not occur. These findings indicate that the transferrin level is an important factor in the regulation of bacterial growth in ascitic fluid and that the low concentration found in cirrhotic patients could facilitate spontaneous bacterial peritonitis.

Adult↗

PubMed1993

Ifosfamide and mitoxantrone as first-line chemotherapy for metastatic breast cancer.

PURPOSE: A phase II trial was performed to evaluate the efficacy and toxicity of a combination of ifosfamide (IFX) and mitoxantrone (MXN) as first-line chemotherapy for metastatic breast carcinoma. PATIENTS AND METHODS: Between January 1990 and August 1991, 48 patients with metastatic breast cancer were entered onto the study. Therapy consisted of IFX 2 g/m2 given as a 1-hour intravenous (IV) infusion on days 1 to 3; mesna 400 mg/m2 as an IV bolus immediately before and 4 hours after IFX administration and 2,000 mg orally 8 hours after IFX administration on days 1 to 3; and MXN 12 mg/m2 as an i.v. bolus on day 3. Cycles were repeated every 21 days until progressive disease (PD) or severe toxicity developed. RESULTS: One patient was considered not assessable for response. Objective regression (OR) was observed in 28 of 47 patients (60%; 95% confidence interval, 46% to 74%). Six patients (13%) had a complete response (CR) and 22 (47%) had a partial response (PR). The median time to treatment failure for the whole group was 9 months (range, 1 to 28); median survival was 19 months (range, 2 to 28). There were no treatment-related deaths. The limiting toxicity was myelosuppression. Leukopenia occurred in 37 patients (77%) and was grade 3 or 4 in 19 patients (40%). Nausea and vomiting were observed in 38 patients (80%), mucositis in 16 patients (33%), and grade 2 hematuria in two patients (4%). Eight patients (16%) developed mild neurotoxicity. CONCLUSION: The combination of IFX plus MXN is an active regimen against metastatic breast cancer with moderate toxicity that deserves further evaluation.

Adult↗

PubMed1993

Immunocytochemical distribution of serotonin and neuropeptide Y (NPY) in mouse adrenal gland.

By the use of immunocytochemical staining methods, we studied the morphology and distribution of 5HT and NPY immunoreactive cells and fibres in the mouse adrenal gland. The 5HT-immunoreactive cells were numerous and widely localized in the medullar tissue. These cells were arranged in three cellular types with regard to their morphological and immunocytochemical features. One of them showed cells with polygonal shape, being intensified like the typical medullary chromaffin cells. These immunoreactive cells were observed arranged in medullar islets. The second 5HT-immunoreactive cellular type was constituted by cells with polygonal shape and strong immunoreactivity. The third one was formed by cells with immunoreactive prolongations. We found some islets of chromaffin non-immunoreactive cells surrounded by immunostained cells. We also observed some 5HT-immunoreactive nerve fibres in the medullar tissue. NPY-like immunoreactivity was detected in both chromaffin and ganglion cells in adrenal medulla. NPY-like immunoreactivity was also detected in nerve fibres at cortical level. In a few cases, we observed medullar 5HT- and NPY-immunoreactive tissue in the adrenal cortex (monotremas).

Adrenal Cortex↗

PubMed1992

Voltage-gated potassium current and resonance in the toadfish saccular hair cell.

Resonance of the membrane potential in response to a perturbing current has been demonstrated in sensory hair cells of many acoustico-lateralis systems and modelled as the result of the interaction of passive membrane properties and the magnitude and kinetics of activation and deactivation of an outward calcium-activated potassium current (IKCa) and an inward calcium current (ICa). However, the majority of the hair cells of the toadfish saccule have, in addition to IKCa, a voltage-gated potassium current (IK) active in the same membrane potential range as IKCa but with considerably slower activation and deactivation kinetics. Additionally, some of these cells have an A current (IA). In the present work, the resonance of cells with these three outward potassium currents were compared with those from cells containing only IKCa. Hair cells with only IKCa produced a high-quality factor (Q) resonance with symmetrical ringing at current onset and termination. In many cells having the IK, resonance could be evoked as a high Q ringing only at the onset of the current pulse. The resonance at command onset was dependent on the presence of IKCa and could be converted into a spike by blocking the IKCa with TEA. Some hair cells with IKCa and IK produced spikes rather than resonance at all holding potentials tested. This spiking was seen in cells with low levels of IKCa or slowly activating IKCa and with cells with IA. The presence of cells with such different response modes implies a difference between hair cells in their role in sensory coding.

Acoustic Maculae↗

PubMed1992

Relationship between fetal weight and litter size in rats: application to reproductive toxicology studies.

The inverse relationship between mammalian fetal weight and litter size has been discussed by many authors, but their opinions reveal no agreement at all. As in toxicity studies of reproduction, both parameters must be correctly evaluated. We investigated the existence of such a relationship in 2466 fetuses from 203 litters of Sprague-Dawley CD control rats. The frequency distribution of fetal weights had a normal adjustment. From the mean weight of fetuses in each litter, the mean fetal weights in each litter size and correlation coefficient were calculated and the regression line was plotted; the correlation coefficient (r = 0.677) was highly significant (P = 0.002), which made evident that there was an inverse relationship between fetal weight and litter size. If fetal weight/litter size inverse relationship is not taken into account when toxicity on the fetal weight is analyzed, wrong conclusions may be reached if the test substance reduces the litter size, provoking embryofoetal mortality. The iatrogenic decrement in fetal weight can be masked by an increment due to the litter size reduction. We suggest that in all three segments of reproductive toxicity studies, litter size must be considered as a covariate to the effect of the test substance on the fetal weight, in order to perform a correct analysis of covariance (ANCOVA), in addition to the dose factor commonly used in common ANOVA.

Animals↗

PubMed1992

Ethinyl estradiol-induced cell proliferation in rat liver. Involvement of specific populations of hepatocytes.

Hepatocyte proliferation was analyzed in vivo during the time course of continuous administration to rats of the liver tumor promoter ethinyl estradiol (EE) at 10 p.p.m. in the diet. EE-induced acute liver hyperplasia was detected in male and female Sprague-Dawley rats as an increased mitotic index of hepatocytes after 2 days of treatment. 5'-Bromodeoxyuridine (BrdU) labeling showed that proliferating hepatocytes were randomly distributed throughout the hepatic lobule. Subsequently, and still during the first few days of continuous EE treatment, hepatocyte proliferation decreased to control levels, and a transient increase in the incidence of apoptosis in the liver was detected. Although consistent with the concept of liver growth regression after mitogen-induced hyperplasia, these results differ from others reported to date in that, in our experiments, the cessation of cell proliferation and the subsequent growth regression occurred without withdrawal of EE in our experiments. After returning to control levels, hepatocellular proliferation again increased between 3 and 6 months of chronic treatment and remained activated during the following months of continuous treatment, as seen by accumulative BrdU labeling. Proliferating hepatocytes were predominantly located in zone 2 of the hepatic lobule at this time, surrounding a periportal zone of vacuolated hepatocytes, which were also induced by the treatment. Moreover, hyperplasia of basophilic hepatocytes was also seen around some portal spaces. In another set of experiments, chronic EE-induced activation was characterized by flow cytometry on hepatocytes isolated from male Fischer rats. Ploidy analysis of hepatocyte cell suspensions showed that the normal polyploid pattern of hepatocytes was altered by EE, the proportion of diploid hepatocytes rising considerably. The results also showed that these diploid cells were the most susceptible hepatocyte population to EE-induced proliferation, as shown by a combination of BrdU labeling and cell sorting methods. In contrast to Sprague-Dawley rats, no vacuolated cells were found histologically in the livers of these animals and the proliferating hepatocytes were located adjacent to the portal areas. These results taken together support the existence of cell target populations in the liver responding to the effects of tumor promoters. The finding that a subpopulation of diploid hepatocytes was the liver cell class most susceptible to proliferation during chronic EE treatment may explain, at least in part, the behavior of EE as a tumor promoter in hepatocarcinogenesis.

Animals↗

PubMed1992

Actinic prurigo.

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Conjunctival Diseases↗

PubMed1992

The insertion site of the temperate phage HB-746 is located near the phage remnant in the pneumococcal host chromosome.

Combined Southern blot hybridization analyses of DNA digests of several clinical strains of Streptococcus pneumoniae have revealed the presence of a gene (hblR), or part of it, similar to the hbl7 gene coding for the cell wall lytic enzyme of the temperate HB-746 phage. The results confirmed that the genome of HB-746, which contains protein covalently linked to the 5' ends of its DNA, becomes integrated into the host strain 8R1 and showed that both the host and phage attachment sites, attB and attP, lie downstream of the 3' end of the structural region of the hblR and hbl7 genes, respectively. The data reported also highlight some evolutionary relationships between phage and bacteria.

Bacteriophages↗

PubMed1992

Development and validation of prognostic models in metastatic breast cancer: a GOCS study.

The significance of several prognostic factors and the magnitude of their influence on response rate and survival were assessed by means of uni- and multivariate analyses in 362 patients with stage IV (UICC) breast carcinoma receiving combination chemotherapy as first systemic treatment over an 8-year period. Univariate analyses identified performance status and prior adjuvant radiotherapy as predictors of objective regression (OR), whereas the performance status, prior chemotherapy and radiotherapy (adjuvants), white blood cells count, SGOT and SGPT levels, and metastatic pattern were significantly correlated to survival. In multivariate analyses favorable characteristics associated to OR were prior adjuvant radiotherapy, no prior chemotherapy and postmenopausal status. Regarding survival, the performance status and visceral involvement were selected by the Cox model. The predictive accuracy of the logistic and the proportional hazards models was retrospectively tested in the training sample, and prospectively in a new population of 126 patients also receiving combined chemotherapy as first treatment for metastatic breast cancer. A certain overfitting to data in the training sample was observed with the regression model for response. However, the discriminative ability of the Cox model for survival was clearly confirmed.

Analysis of Variance↗

PubMed1992

Acute toxicity studies of sertaconazole.

The acute toxicity of 7-chloro-3-[1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy- methyl]benzo[b]thiophene (sertaconazole, FI-7045, CAS 99592-32-2) was evaluated in mice and rats after single administration by oral, subcutaneous and intraperitoneal routes. The latter intended to ensure maximum blood levels, since intravenous route was unfeasible due to drug insolubility in water. LD50 was indeterminable (greater than 8000 mg/kg) in all routes of dosing. According to these results, and having furthermore proved the absorption of the test substance after oral administration, sertaconazole was concluded to be very safe in the event of overdose or accidental ingestion.

Administration, Oral↗

PubMed1992

Subacute toxicity and maximum tolerable dose of sertaconazole in repeated administration studies.

28-Day oral and dermal subacute toxicity studies of 7-chloro-3-[1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl) ethoxy-methyl] benzo [b] thiophene (sertaconazole, FI-7045, CAS 99592-32-2), were carried out. The oral studies included the evaluation of subacute toxicity in rat (dose levels of 50, 150 and 300 mg/kg) and maximum tolerable dose in repeated administration in ferrets (consecutive dose levels in accordance with a geometric progression of 50, 75, 112.5, 168 and 250 mg/kg), which were the animal species intended for chronic toxicity studies. The dermal studies included the evaluation of subacute toxicity in rats and rabbits (1 ml/kg of a 2% cream). The results, in general, have shown low toxic effects, which can be summarized as a slight non-significant hepatomegalia in the rat with increased gamma-GTP and alkaline phosphatase values and a high urinary pH value; no histopathological changes were observed. These effects are characteristic of azole derivatives and are therefore common to other antifungals with this chemical group.

Administration, Oral↗

PubMed1992

Chronic toxicity studies of sertaconazole after oral administration to rats and ferrets.

Six-month chronic oral toxicity studies of 7-chloro-3-[1-(2, 4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy-methyl] benzo[b]thiophene (sertaconazole, FI-7045, CAS 99592-32-2) were carried out in rats and ferrets. The dose levels used were 50, 150 and 300 mg/kg in rats and 50, 150 and 250 mg/kg in ferrets. There was no mortality associated with the drug in either of the two species. The results obtained show that the toxic effects may be summarized as a smaller body weight increase in rats at 150 and 300 mg/kg and in male ferrets at 250 mg/kg. Food consumption decreased significantly in rats at 300 mg/kg, and was not proportional to the doses of 150 and 50 mg/kg. In serum biochemistry, increases in alkaline phosphatase in rats, ALT in male ferrets at 150 and 250 mg/kg and AST only at 250 mg/kg were observed. BUN increased at 150 and 250 mg/kg in ferrets.

Animals↗

PubMed1992

Reproduction toxicity of sertaconazole. Segment II (teratology) and Segment III (peri-postnatal toxicity).

The reproduction toxicity of 7-chloro-3-[1-(2,4-dichlorophenyl)-2- (1H-imidazol-1-yl)ethoxy-methyl]benzo[b]thiophene (sertaconazole, FI-7045, CAS 99592-32-2) (50, 100 and 150 mg/kg by oral route) has been investigated by performing two studies: the embryotoxicity or teratology study in rats and rabbits, and the peri-postnatal toxicity study in rats. According to the results obtained from the embryotoxicity studies, there was no maternal toxicity in either of the two species studied. The only embryofoetal abnormalities with statistical and toxicological significance were observed at the dose of 150 mg/kg in the teratology study on rabbits: hepatomegalia, pericardial oedema and peritoneal and hepatic haemorrhages. The results of the peri-postnatal study showed that the only maternal effect relating to the drug was an increase, proportional to the dose, in the weight of the ovaries, which was significant at the dose of 150 mg/kg. With reference to the offspring, only a reduction in the viability index at 150 mg/kg was observed. The non observed effects level (NOEL) for all three studies can be estimated at 100 mg/kg.

Aging↗

PubMed1992

Genotoxicity studies on sertaconazole.

A series of 6 studies has been performed to evaluate the potential genotoxic effect of 7-chloro-3-[1-(2,4-dichlorophenyl)-2-(1H- imidazol-1-yl)ethoxy-methyl]benzo[b]thiophene (sertaconazole, FI 7045, CAS 99592-32-2). From these studies, the reverse mutation assay on Salmonella typhimurium, sex-linked recessive lethal mutations on Drosophila and genetic mutations in cultured mammal cells allowed to study the genetic mutations in prokaryotes and eukaryotes. In vitro and in vivo chromosomal aberrations were studied using human lymphocytes cytogenetic test, micronucleus test and sister chromatid exchange test. The results obtained in these studies, which are complemented one another, demonstrated that sertaconazole did not induce any signs of promutagenic, mutagenic or clastogenic activity or interference with the chromosomal segregation process.

Animals↗

PubMed1992

Dermal tolerance and phototoxicity studies of sertaconazole.

The local dermal tolerance of 7-chloro-3-[1-(2,4-dichlorophenyl)-2-(1H- imidazol-1-yl)ethoxy-methyl]benzo[b] thiophene (sertaconazole, FI 7045, CAS 99592-32-2) was evaluated in hairless rats and albino rabbits. Test substance was applied in 2% powder (0.5 g), gel (0.5 ml) and solution (0.5 ml) formulations to rats (this is the concentration intended for the pharmaceutical preparation) and in 6% cream (0.5 ml) to rabbits (this concentration was used to estimate an overdose maximal effect). After 3- and 24-h exposure of the test substance to animals, they were observed for erythema and oedema. Sertaconazole may be considered as non irritant, since its primary irritation index was less than 0.5 in all the tests. A phototoxicity study was also carried out on guinea pigs with 1 ml 2% cream per animal, compared with psoralene as a positive control. Sertaconazole did not present any risk, since the phototoxicity level reached was null, with 2 being the minimum value considered as having toxic significance.

Animals↗