Search PubMed⌕ Search

Biomedical subjects

A Marco

Publications and source records attributed to A Marco.

At least 19 recordsLinked to original sources
PubMed1999

Identification of a disturbance signal in larval red-legged frogs, Rana aurora.

Animals that are warned about the presence of a predator are more likely to avoid and/or survive an encounter with a predator. Chemical signals released by disturbed or injured conspecifics may provide prey animals with an early warning. In this study we conducted experiments to determine whether larval red-legged frogs respond to chemical stimuli produced by disturbed conspecifics and to examine the chemical compounds that may act as the alarm signal. In laboratory tests, groups of tadpoles responded with antipredator behaviours when exposed to chemical cues of disturbed conspecifics but not when exposed to chemical cues of control (undisturbed) conspecifics. In subsequent tests, disturbed animals increased ammonium (the main metabolic waste of tadpoles) excretion relative to undisturbed individuals. When tadpoles were exposed to low-level ammonium concentrations (1 mg NH4+/litre), they responded by increasing antipredator behaviours. Our results suggest that red-legged frog tadpoles release a chemical that provides conspecifics with an early warning of predator presence, and that ammonium (NH4+) may be a component of the disturbance signal. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Effect of gastric pH on the relative oral bioavailability and pharmacokinetics of temozolomide.

PURPOSE: Temozolomide is an imidazotetrazine alkylating agent which undergoes chemical conversion at physiological pH to the active species 5-(3-methyltriazene-1-yl)imidazole-4-carboxamide (MTIC) but is stable at acid pH. This study evaluated the effect of an increase in gastric pH, through the use of ranitidine, on the oral bioavailability and plasma pharmacokinetics of temozolomide and MTIC. METHODS: Fifteen patients with advanced cancer were enrolled of which 12 were evaluable, all of whom had pharmacokinetic blood sampling. Each patient received temozolomide 150 mg m(-2) day(-1) for 5 days in cycle 1 and also received ranitidine 150 mg every 12 h either on days 1 and 2 or days 4 and 5. Gastric pH was monitored by the use of the Heidelberg capsule system. RESULTS: Following the administration of ranitidine there was a rise in gastric pH by 1-2 pH units over the duration of the study period (pH range 2.2-5.2 without ranitidine and 3.5-6.0 with ranitidine). There was no difference in the pharmacokinetic parameters of temozolomide or MTIC with or without the concomitant administration of ranitidine. There was however, a lower C(max) for temozolomide and MTIC for patients receiving ranitidine on day 1 and 2 versus day 4 and 5. Temozolomide was rapidly absorbed [time to maximum plasma concentration (t(max)) 1.8 h] and eliminated [elimination half-life (t(1/2)) 1.8 h] and MTIC followed a similar pattern with a t(max) of 1.9 h and a t(1/2) of 1.9 h. Overall, the AUC of the MTIC represented about 2-4% of the AUC for temozolomide.

Administration, Oral↗
PubMed1999

Repeated oral dosing with Listeria monocytogenes in mice as a model of central nervous system listeriosis in man.

Human listeriosis is a food-borne disease of immunosuppressed or previously healthy adults. The repeated oral administration of a sublethal dose (5x10(9)colony-forming units) of Listeria monocytogenes for 7 or 10 consecutive days led to the development of severe central nervous system (CNS) lesions in 25% of experimental mice. Histopathological examination of the brain revealed rhombencephalitis and ventriculitis as two distinct inflammatory patterns, resembling those seen in human listeriosis. This model would seem to be potentially useful for research on pathogenesis, predisposing factors and therapy in CNS listeriosis in man. 1999 W.B. Saunders and Company Ltd.

Administration, Oral↗
PubMed1999

[Stesioneuroblastoma. A case report].

The esthesioneuroblastoma is a rare type of tumor located in nasal cavity, malignant, that is able to take a very aggressive growth pattern, but it has treatment with cure expectations when it is discovered in its initial stages by surgery or intensive radiotherapy and/or chemotherapy in the more developed ones. Due to its low incidence and its clinic presentation as a benign process that makes the patient takes it as a non important process, the esthesioneuroblastoma, as others malignant diseases of the nasal cavity, is frequently diagnosed at developed stages as this case that we present here.

Adult↗
PubMed1998

Sex recognition and mate choice by male western toads, Bufo boreas.

In field-based choice experiments, we examined sex recognition and mate choice in male western toads, Bufo boreas. When given a simultaneous choice between a male and a female of equal size, males did not discriminate between the sexes and attempted to amplex a male or a female with equal frequency. When a test male clasped a stimulus male, the stimulus male uttered a release call that caused the test male to release the stimulus male. Male-male amplexus never lasted more than 3 s, but male-female amplexus was tenacious and prolonged. Furthermore, males discriminated between gravid females that differed in body size, choosing larger gravid females over smaller ones, but they did not discriminate between gravid females or non-gravid females of equal size. In choice tests that excluded chemical cues, males jumped more frequently towards large females than small ones. Given that females are significantly larger than males, selecting larger individuals as potential mates increases the probability that males amplex with a female. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Phase I study of temozolomide in paediatric patients with advanced cancer. United Kingdom Children's Cancer Study Group.

A phase I study of temozolomide administered orally once a day, on 5 consecutive days, between 500 and 1200 mg m(-2) per 28-day cycle was performed. Children were stratified according to prior craniospinal irradiation or nitrosourea therapy. Sixteen of 20 patients who had not received prior craniospinal irradiation or nitrosourea therapy were evaluable. Myelosuppression was dose limiting, with Common Toxicity Criteria (CTC) grade 4 thrombocytopenia occurring in one of six patients receiving 1000 mg m(-2) per cycle, and two of four patients treated at 1200 mg m(-2) per cycle. Therefore, the maximum-tolerated dose (MTD) was 1000 mg m(-2) per cycle. The MTD was not defined for children with prior craniospinal irradiation because of poor recruitment. Plasma pharmacokinetic analyses showed temozolomide to be rapidly absorbed and eliminated, with linear increases in peak plasma concentrations and systemic exposure with increasing dose. Responses (CR and PR) were seen in two out of five patients with high-grade astrocytomas, and one patient had stable disease. One of ten patients with diffuse intrinsic brain stem glioma achieved a long-term partial response, and a further two patients had stable disease. Therefore, the dose recommended for phase II studies in patients who have not received prior craniospinal irradiation or nitrosoureas is 1000 mg m(-2) per cycle. Further evaluation in diffuse intrinsic brain stem gliomas and other high-grade astrocytomas is warranted.

Adolescent↗
PubMed1998

Intestinal cryptococcosis in a common marmoset (Callithrix jacchus).

A five-year-old female common marmoset (Callithrix jacchus) died after a one-month clinical course of nonspecific signs. Pathologic findings were acute diffuse fibrinonecrotizing enteritis and granulomatous endolymphangitis of intestinal and mesenteric lymphatic vessels. Both lesions were associated with a marked proliferation of Mayer's mucicarmine-positive, 4 to 15 microm yeasts that were surrounded by a wide clear halo. The infection was probably acquired by oral route. Other findings included moderate multifocal granulomatous and necrotizing hepatitis and mesangial nephropathy. Although the immunological status of this marmoset was unknown, cryptococcosis might induce primary lethal intestinal infections in callitrichids.

Animals↗
PubMed1998

Predictors of adherence to tuberculosis treatment in a supervised therapy programme for prisoners before and after release. Study Group of Adherence to Tuberculosis Treatment of Prisoners.

The prison population is a high-risk group for tuberculosis (TB). This investigation aimed to study predictive factors of treatment adherence among prisoners involved in a pilot programme of supervised treatment. The study included TB patients from the Men's Penitentiary Center of Barcelona (MPCB) in 1995. Directly observed therapy (DOT) was carried out in the infirmary or in a methadone programme. Released prisoners were referred to the municipal maintenance methadone programmes (MMP) and other social resources. Incentives and enablers were used to improve compliance (economic aid for nutritional and housing needs, methadone programmes and admittance to a sociosanitary centre). The outcome of the patients' adherence was classified as follows: completed, defaulted, dead or transferred out. Factors associated with adherence were investigated through logistic regression. The programme included 62 patients, 43 of whom were intravenous drug users (IVDU) and 46 were infected with the human immunodeficiency virus (HIV). Nineteen had previously had TB and 32 were released from prison during TB treatment. Overall adherence was 89%; 97% among those who completed treatment in prison, and 79% among those who completed treatment outside prison (p=0.05). Ninety-five per cent of IVDU in an MMP completed treatment. Homeless or alcoholic exprisoners completed treatment only if they were admitted to sociosanitary centres. DOT throughout treatment resulted in better adherence (odds ratio (OR)= 16.80; confidence interval (CI): 2.42-116.2)). Those who were incarcerated throughout treatment also showed better adherence (OR= 7.36; CI: 0.79-48.16). Antituberculosis treatment adherence in prisoners was high even after release with adequate co-ordination among intrapenitentiary and extrapenitentiary programmes. Maintenance methadone programmes proved very useful in intravenous drug users, as did admittance to sociosanitary centres for indigent or alcoholic exprisoners undergoing treatment.

AIDS-Related Opportunistic Infections↗
PubMed1997

High-performance liquid chromatographic determination and stability of 5-(3-methyltriazen-1-yl)-imidazo-4-carboximide, the biologically active product of the antitumor agent temozolomide, in human plasma.

5-(3-Methyltriazen-1-yl)-imidazo-4-carboximide (MTIC) is a highly unstable compound which is believed to be the biologically active degradation product of the antitumor agent temozolomide. An HPLC method has been developed and validated for the analysis of MTIC in human plasma. Because of the instability of MTIC, sample processing was kept to minimal. The method involved precipitation of plasma protein with methanol followed by analysis of the supernatant using reversed-phase column and UV detection at 316 nm. The linearity (r>0.99), precision (C.V.<9%) and accuracy (bias<5%) were satisfactory. The lower limit of quantitation (LOQ) was 10 ng/ml. The recovery of MTIC and internal standard was > or = 86.7%. MTIC was stable in plasma though three freeze-thaw cycles, and was stable at 4 degrees C for 1 h and at -80 degrees C for at least 70 days. MTIC may be unstable at 10 degrees C in processed samples; therefore, samples were placed in the autosampler (10 degrees C) immediately prior to injection. By using this analytical method, MTIC was quantified in plasma of cancer patients (n=12) within 0.25-12 h after oral administration of temozolomide at 150 mg/m2. The mean maximum plasma concentration (Cmax) was 211 ng/ml which was observed at a mean Tmax of 1.88 h post dose. MTIC disappeared rapidly from plasma with an apparent in vivo half-life (t1/2) of 1.9 h similar to that of temozolomide. Following in vitro incubation of MTIC in human plasma at 25 degrees C, MTIC disappearance was bioexponential with estimated t1/2 values of 25 and 60 min for the first and second phases, respectively. Therefore, the elimination t1/2 of MTIC in human in vivo (1.9 h) was controlled by the rate of its formation from temozolomide.

Administration, Oral↗
PubMed1997

Survival of heated Bacillus coagulans spores in a medium acidified with lactic or citric acid.

The influence of the intensity of heat treatments on the capacity of citric or lactic acid to prevent growth of survivors of Bacillus coagulans spores after 10 days storage at 35 degrees C was studied. In most cases, the number of survivors during storage decreased. The extent of this spore inactivation depended on the intensity of previous heat treatment and the pH of the medium and the acidulant used. The inactivating effect of storage was pronounced even at pH values less acidic than those used by the canning industry. Citric acid was more effective than lactic acid on spores given only low heat treatments, but lactic was more effective against those given more severe heat treatments. The severity of heat treatment required for lactic to be more effective than citric acid increased with pH of the medium. Heat treatment also required increased pH for heated spores to grow. pH 4.6, regardless of acidulant used, was unable to prevent growth of unheated spores but a less acidic pH (pH 5.2) did prevent growth even when spores had been given only mild heat treatments (10 s at 100 degrees C).

Bacillus↗
PubMed1995

[Characteristics of AIDS cases detected at a prison in Barcelona (1991-1993)].

OBJECTIVE: To describe the cases of AIDS detected in a Barcelona prison. DESIGN: A prospective study. SETTING: A penitentiary for men in Barcelona. PATIENTS: All those inmates who had AIDS or were diagnosed with the illness during their stay in prison during the 36 months between 1/1/1991 and 31/12/93. RESULTS: 220 cases of AIDS (91.7% PVDA), 60% of which were diagnosed in prison. The PVDA were younger (p < 0.0001). There were a greater number of Spaniards among the UDVP (p < 0.01) and among those with tattoos (p < 0.001). The first manifestation of the disease in 53% of the cases was extrapulmonary Tuberculosis. CONCLUSIONS: Prisons are key places in the prevention and monitoring of HIV infection. The use of care programmes, including maintenance programmes using Methadone, for drug-dependent patients are recommended. The continuation of programmes tracking Tuberculosis, the main illness related to HIV infection in prison, is also recommended.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Myoepithelial hamartoma of the ileum: a rare cause of intestinal intussusception in children.

Herein we present a case report of a 2-year-old male child who suffered an ileocecal intussusception not reduced by pneumoenema. At the apex of the intussusception there was a 2 cm tumor. The pathologic diagnosis was myoepithelial hamartoma. In a review of the literature we could find no previous reference to myoepithelial hamartomas located in distal ileum causing intussusception in children.

Child, Preschool↗
PubMed1995

Differential characteristics of AIDS patients with a history of imprisonment.

BACKGROUND: AIDS is among the leading causes of death in prisons, but there is little information about AIDS patients with a history of imprisonment. METHODS: AIDS patients diagnosed in Barcelona between 1988 and 1993 were studied. Those with prison histories were compared to those without, with respect to epidemiological variables, including survival analysis. RESULTS: 28.5% of 2336 AIDS patients, 49.4% of intravenous drug users (IVDU) and only 2.6% of homosexuals who were not IVDU had a prison history. Those with prison histories, compared to those without, were younger (median age of 30.6 versus 36.4, P < 0.0001), more often IVDU than homosexuals (87.8% versus 35.8%, OR = 36.9, 95% CI: 22.6-60.8, P < 0.0001), and diagnosed with AIDS because of extrapulmonary tuberculosis (32.0% versus 14.7%, P < 0.001). Among IVDU, those with prison histories were more frequently males (OR: 2.2; 95% CI: 1.6-2.9), lived in the poorest district of Barcelona more frequently than in the richest district (OR: 6.6; 95% CI: 3.4-12.9) and presented with extra-pulmonary tuberculosis more frequently than Pneumocystis carinii pneumonia (OR: 1.7; 95% CI: 1.2-2.4). Longer survival in the prison group did not persist when adjusted for age and AIDS-defining disease. Those with prison histories who presented with AIDS with only extrapulmonary tuberculosis had better probability of survival than those who presented only with P. carinii pneumonia (P < 0.001). CONCLUSIONS: AIDS patients in Barcelona with prison histories tended to be younger, more likely to be IVDU, and to present with extrapulmonary tuberculosis as an AIDS-defining illness than other patient groups. Better survival appears to be related to age and AIDS-defining illnesses in the prison group. The fact that half the IVDU AIDS cases had prison histories has important implications for the care and prevention of HIV, tuberculosis, and drug abuse in comparable prison settings.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Pharmacokinetics and dose proportionality of ceftibuten in men.

The pharmacokinetics and dose proportionality of ceftibuten were evaluated in healthy male volunteers receiving single oral doses of 200, 400, and 800 mg of ceftibuten. The drug was absorbed with similar times to the maximum concentration of drug in plasma for all three doses. Concentrations of ceftibuten in plasma increased with increasing dose. Analysis of variance was carried out on the dose-adjusted values for the maximum concentration of drug in plasma and the area under the plasma concentration-time curve; the results indicated that the concentrations in plasma after the 200- and 400-mg doses were dose proportional, and after the 800-mg of dose they were less than dose proportional. The elimination half-life from plasma ranged from 2.0 to 2.3 h and was independent of dose. The total excretion of unchanged ceftibuten in urine accounted for 53 to 68% of the dose, and the renal clearance was estimated to be 53 to 61 ml/min after all doses. The amount of ceftibuten-trans, the major in vitro and in vivo conversion product of ceftibuten, was low in both plasma and urine.

Adult↗
PubMed1994

Liquid chromatographic determination of ceftibuten, a new oral cephalosporin, in human plasma and urine.

Two liquid chromatographic methods with UV detection were developed for the determination of ceftibuten in human plasma and urine. Diluted plasma samples were directly injected onto a reversed-phase column without prior protein precipitation while diluted urine samples were processed through an automated on-line sample clean-up procedure using column-switching. Both methods were linear over clinically relevant concentration ranges in plasma (from 0.1 to 50 micrograms ml-1) and urine (from 0.5 to 60 micrograms ml-1). The methods showed acceptable precision (RSD < 20%) and accuracy (bias < 15%) at the limit of quantitation (LOQ) for ceftibuten in plasma and urine. These LOQs represented the lowest concentrations of ceftibuten in plasma (0.1 micrograms ml-1) and urine (0.5 micrograms ml-1) that could be measured with acceptable precision and accuracy. RSDs for both within-day and between-day analyses were < or = 12% for plasma and < 7% for urine. These methods have been used successfully for the analysis of ceftibuten in plasma and urine following single oral doses of 200, 400 and 800 mg in man.

Administration, Oral↗