Biomedical subjects

M Guerra

Publications and source records attributed to M Guerra.

At least 19 recordsLinked to original sources

PubMed2000

Extracellular matrix proteins increase the expression of pro-TRH and pro-protein convertase PC1 in fetal hypothalamic neurons in vitro.

External clues for neuron development include extracellular matrix (ECM) molecules. To explore ECM influence on the early development of peptide phenotype in the CNS, we have compared pro-TRH levels in primary cultures of rat hypothalamic cells plated either on poly-lysine (PL) (control) or on PL plus one of various ECM molecules at 10 microgram/ml. Fetal day 17 cells plated at a density of 1250/mm(2) were grown in a serum free medium made of Neurobasal medium supplemented with B27 (GIBCO). Cultures, consisting mainly of neurons, were analyzed at DIV 2. ECM proteins induced morphological effects in agreement with previously published studies. The amount of pro-TRH per dish, quantified by Western blotting, was increased to 275% for laminin, 191% for fibronectin and 173% for tenascin-C (control=100%); there was no effect of vitronectin. Laminin or fibronectin did not change pro-TRH mRNA or TRH levels but enhanced levels of the pro-protein convertase PC1 suggesting that the ECM molecules did regulate the translational status of pro-TRH. In conclusion, we have shown that some ECM proteins increased pro-TRH level in vitro; this may contribute to the enhancement of pro-TRH levels observed early in vivo in the hypothalamus.

Animals↗

PubMed2000

Stormy onset of benign childhood epilepsy with occipital paroxysmal discharges.

We studied six children with ages ranging from 4 to 10 years who were affected by childhood epilepsy with occipital paroxysms and presented after a stormy onset with prolonged loss of consciousness for 6-14 h. In all these patients, seizures were preceded by visual symptoms in the form of colored circular disks. A CT scan was performed immediately after the onset of symptoms and was normal in all patients. Routine laboratory and cerebrospinal fluid examinations were normal in all patients. The interictal EEG was characterized by continuous or subcontinuous occipital spike wave discharges, which disappeared after the patients' eyes opened. We carried out a 7-year follow-up of all these patients. Only two patients were treated with antiepileptic drugs. The therapy (phenobarbital, clobazam) in the two patients did not induce changes in the EEG pattern. The first did not suffer any further seizures. The second patient had two more seizures (at 8 and 18 months from the onset) with phosphenes, confusional state, and involuntary movements followed by loss of consciousness. Among the other four patients, who did not receive any treatment, only one had any other seizures. The stormy onset of the syndrome described in our six patients emphasizes the extreme variability in the presentation of this type of childhood epilepsy. Our follow-up confirms the good prognosis of this epilepsy even when it has a stormy onset.

Child↗

PubMed2000

Childhood epilepsy with occipital paroxysms and benign nocturnal childhood occipital epilepsy.

Two types of childhood epilepsy have recently been reported: childhood epilepsy with occipital paroxysms, and benign nocturnal childhood occipital epilepsy. This article reports the clinical evolution, electroencephalographic (EEG) changes, and response to therapy of eight children with childhood epilepsy with occipital paroxysms (five boys and three girls, aged from 1 1/12 to 8 years) and eight children with benign nocturnal childhood occipital epilepsy (six boys and two girls, aged from 1 4/12 to 8 3/12 years). A careful clinical and EEG follow-up of at least 7 years was carried out for all patients. At the end of follow-up, all but one of the patients with childhood epilepsy with occipital paroxysms were seizure-free, and only two were still receiving anticonvulsant drugs. All but three children had a normal EEG, and normal mental development was observed in all but two cases. Patients with benign nocturnal childhood occipital epilepsy had a good long-term prognosis; all but two children with benign nocturnal childhood occipital epilepsy had a normal EEG. These two patients showed learning disabilities and poor school performances, and required remedial education. Therefore, although childhood epilepsy with occipital paroxysms and benign nocturnal childhood occipital epilepsy are two different types of epilepsy, the long-term prognosis seems to be similar.

Anticonvulsants↗

PubMed2000

Heterochromatin banding patterns in Rutaceae-Aurantioideae--a case of parallel chromosomal evolution.

The heterochromatin banding patterns in the karyotypes of 17 species belonging to 15 genera of Rutaceae subfamily Aurantioideae (= Citroideae) were analyzed with the fluorochromes chromomycin (CMA) and 4'-6-diamidino-2-phenylindole-2HCl (DAPI). All species were diploids, except one tetraploid (Clausena excavata) and two hexaploids [Glycosmis parviflora agg. (aggregate) and G. pentaphylla agg.]. There are only CMA/DAPI bands, including those associated with the nucleolus. Using recent cpDNA (chloroplast DNA) sequence data as a phylogenetic background, it becomes evident that generally more basal genera with rather plesiomorphic traits in their morphology, anatomy, and phytochemistry exhibit very small amounts of heterochromatin (e.g., Glycosmis, Severinia, Swinglea), whereas relatively advanced genera from different clades with more apomorphic characters display numerous large CMA bands (e.g., Merrillia, Feroniella, Fortunella). Heterochromatin increase (from 0.7 to 13.7%) is interpreted as apomorphic. The bands are mostly located in the larger chromosomes and at telomeric regions of larger arms. However, one of the largest chromosome pair has been conserved throughout the subfamily with only very little heterochromatin. The heterochromatin-rich patterns observed in different clades of Aurantioideae appear quite similar, suggesting a kind of parallel chromosomal evolution. In respect to the current classification of the subfamily, it is proposed to divide Murraya s.l. (sensu lato) into Bergera and Murraya s.s. (sensu stricto) and to place the former near Clausena into Clauseneae s.s. and the latter together with Merrillia into Citreae s.l. The subtribes recognized within Clauseneae s.s. and Citreae s.l. appear heterogeneous and should be abandoned. On the other hand, the monophyletic nature of the core group of Citrinae, i.e., the Citrus clade with Eremocitrus, Microcitrus, Clymenia, Poncirus, Fortunella, and Citrus, is well supported.

Journal Article↗

PubMed2000

A histochemical study of the rheumatoid synovium: focus on nitric oxide, nerve growth factor high affinity receptor, and innervation.

OBJECTIVE: The synovium of patients with rheumatoid arthritis (RA) is characterized by massive cell proliferation, neoangiogenesis, and apoptosis. The nature of potential repressors/inducers of these phenomena is still largely unknown. We investigate if nitric oxide (NO) and nerve growth factor (NGF) can be considered potential mediators in these phenomena in RA. METHODS: Synovium of 15 patients with RA in active phase and synovium of 14 patients without synovial inflammation were processed for histochemical (NADPH-diaphorase) and immunohistochemical visualization of different isoforms for the NO synthesis enzyme NO synthase (NOS) and for NGF high affinity receptor trkA. RESULTS: Inducible NOS (iNOS) immunoreactivity and NADPH-diaphorase positivity were found in synoviocytes, fibroblast-like synoviocytes, fibroblasts, and inflammatory cells in the rheumatoid synovium. In the same areas and in the same cell types, although not in the same cells, we also found positivity for the NGF high affinity receptor trkA. CONCLUSION: We suggest that all elements involved in the transduction pathway that is activated by NGF and that proceeds through NO and tumor suppressor p53 are present in the synovium during RA, controlling cell cycle arrest, cell differentiation, and apoptosis.

Arthritis, Rheumatoid↗

PubMed1999

Radiation sterilization of a bifunctional cement formulation of hydroxilapatite-plaster-polymers.

A sterilization method based on the use of gamma ionizing radiation was applied to a cement formulation of hydroxilapatite, plaster and polymers to be used in bone restorations in dental, aesthetic, and neurological surgery. After the cement was exposed to a dose of 21.5 kGy it reached the sterility assurance level which was necessary for its employment in surgical applications as specified by International Standard ISO ordinate 11137: Radiation Sterilization of Health Care Products. No variation in the initial cement composition or processing parameters, such as working or setting time and molding quality was observed due to sterilization. Its characteristics as a drug delivery system were also not affected. Therefore, radiation sterilization provides a feasible alternative to conventional sterilization methods such as dry/wet heat and ethylene oxide.

Biocompatible Materials↗

PubMed1999

Ion release from orthodontic appliances.

OBJECTIVE: The microbiological and enzymatic characteristics of the oral cavity would seem to provide a suitable environment for the corrosion of metals. We assayed the release of metal ions from one orthodontic appliance which included two 304 and 316 steel molar bands, ten 316 steel brackets, one nickel-titanium archwire and a brazing alloy to connect the elements of molar bands and brackets. METHODS: The orthodontic appliance was dipped in both inorganic (pH 3.5-6.5) and organic acid solutions (w/v 1% each of tartaric, citric and ascorbic acid at pH 2.2 or 1.5% each of lactic and acetic acid at pH 2.5). The release of nickel (Ni), chromium (Cr), copper (Cu), silver (Ag) and palladium (Pd) was determined using an atomic absorption spectrophotometer Varian AA 10. RESULTS: The release of Ni, Cr and Cu was markedly less at pH 6.5 than at pH 3.5 at all time points in acid solution. Daily release/single appliance after the first day decreased. Contrary to expectations, appliances immersed in organic acid solutions at pH 2.2 or 2.5 after 28 days generally released an amount of ions similar to that observed in inorganic acid solution at pH 3.5, with the exception of Cu. Release of silver and palladium, two metals present in the brazing alloy, proved to be very low (approximately 0.2 microgram after 28 days). CONCLUSIONS: The daily release of Ni, Cu and Cr by an orthodontic appliance in acid pH, particularly favourable to corrosion, was well below that ingested with a normal daily diet. It is therefore concluded that the quantities of metal ions released in our experimental conditions should not be cause for concern in utilising the appliance.

Chromium↗

PubMed1999

Pharmacokinetics of rifabutin in HIV-infected patients with or without wasting syndrome.

AIMS: The purpose of the study was to compare the pharmacokinetic parameters of rifabutin obtained in a group of patients without wasting syndrome (NWS) with those obtained in a group with wasting syndrome (WS). METHODS: A single dose of 300 mg rifabutin was administered in the fasting state to the patients in both study groups and blood samples were scheduled to be collected at the following times: 0 (predose), 0.5, 1, 2, 3, 4, 6, 8, 24, 48, 72 and 96 h following administration. Data were analysed using noncompartmental methods. The pharmacokinetic parameters of rifabutin in patients with and without wasting syndrome were compared using the Mann-Whitney U-test. RESULTS: Cmax was 0.34+/-0. 14 mg l-1 in NWS patients and 0.55+/-0.16 mg l-1 (P=0.01) in patients with WS. tmax was 4.2+/-1.5 and 3.3+/-2.3 h (P=0.17) in NWS and WS patients, respectively. The AUCs were similar in the two study groups. V/F was 2905+/-1646 l in NWS patients and 1701+/-492 l (P=0.07) for the WS group. These differences are less pronounced following normalization of V/F to patients body weight (43.7+/-20.1 vs 35.4+/-10.3 l kg-1 ). t1/2,lambdaz tended to be shorter in patients with WS (31.4+/-12.9 vs 46.0+/-23.5 h, P=0.12). CONCLUSIONS: Our study suggests that the pharmacokinetics of rifabutin in patients with wasting syndrome are not altered to a degree that is clinically important.

Adult↗

PubMed1999

Association between the rate of CD4+ T cell decrease and the year of human immunodeficiency virus (HIV) type 1 seroconversion among persons enrolled in the Swiss HIV cohort study.

The aim of this study was to investigate the early CD4+ T cell response among human immunodeficiency virus type 1 (HIV-1) seroconverters in relation to their year of seroconversion. Study participants were enrolled in the Swiss HIV Cohort Study between 1985 and 1995 and had not received antiretroviral treatment. The slope of the CD4+ T cell count within 2 years after seroconversion was significantly associated with the year of seroconversion, by sex and by use of injection drugs, when controlling for initial CD4+ cell count. These results show that the loss of CD4+ cells might be associated with the year of seroconversion, suggesting a change in the pathogenesis of HIV across the years. If these results are confirmed, they could have important implications for the pathogenesis of and therapeutic strategies for HIV-1 infection.

Adolescent↗

PubMed1999

[Nutrient utilization in children with acute diarrhea fed with formulas containing chicken and soybean].

The objective of this study was to measure in children with acute diarrhea the apparent absorption and retention of the macronutrients and some micronutrient present in a formula prepared with chicken and a formula prepared with soybean protein. Fourteen male children (9 months old) with acute diarrhea were assigned to each of these formulas and the consumption and excretion of the studied nutrients were monitored during 48 h. The results showed that the children assigned to the chicken formula consumed more protein and less fat than those in the soybean protein formula. These differences however were associated with differences in the composition of the formulas offered rather than to differences in protein or fat utilization. Fecal mass (800 g/48 h) was similar in both groups and the macronutrient content of the feces, reflected well the amount consumed. The apparent absorption of fat (63%), nitrogen (75%) and carbohydrates (78%) resulted similar in both groups and there were no differences in the retention of nitrogen which approximated 55%. The digestible energy and the metabolizable energy of both formulas, also resulted equal. In general the children excreted more urinary ammonia and less creatinine than healthy children but there were no differences in the excretion of these metabolites between the children assigned to the chicken or to the soybean protein formulas. The retention of Zn (47%) and Ca (72%) were also similar in both groups and they excreted a high (0.17 mg/48 hr) but similar amount of Vitamin A. In summary, these results showed that from a nutritional point of view, the chicken and the soybean protein formulas were equally utilized during the acute phase of diarrhea.

Acute Disease↗

PubMed1998

Elution of lipopolysaccharides from polyacrylamide gels.

A simple procedure for elution in water of bacterial lipopolysaccharides (LPS) from sodium dodecyl sulfate-polyacrylamide gels is described. It consists of the combination of three principal steps: first, highly sensitive on-gel LPS detection (1-10 ng/band) with zinc-imidazole (negative or reverse staining); second, washing of the individual LPS band in a solution of a zinc-complexing agent (e.g., 100 mM EDTA); and finally, elution of the LPS (100-200 microliters water for a 0.5-microgram LPS band) from gel microparticles for 3 h at room temperature. Using this procedure, we have successfully eluted a variety of LPS forms from Bordetella pertussis, Escherichia coli 0111:B4, E. coli K-235, Salmonella enteritidis, and Pseudomonas aeruginosa. Elution recovery of rough or semismooth LPS was about 70-80%, while that of smooth LPS was only about 10%. Eluted LPS was biologically active as tested by limulus amebocyte lysate and TNF-alpha assays.

Acrylic Resins↗

PubMed1998

Understanding the mechanism of the zinc-ion stains of biomacromolecules in electrophoresis gels: generalization of the reverse-staining technique.

We have recently shown that a few nanograms of protein separated by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels can be detected by reverse-staining, exploiting the precipitation reaction between zinc(II) and imidazole. Modifications of this method have also been generated to detect gel-isolated nucleic acids and bacterial glycolipids. Because there is no recourse to chemical modifiers, the reverse-staining technique has been valuable when micropreparing these biomacromolecules for later use or characterization. The mechanism underlying the reverse-staining effect, however, remains incompletely understood and this has prevented a further generalization of the technique. Here, we have conducted physicochemical experiments and identified zinc imidazolate (ZnIm2) as the main component of the precipitate that forms along the surface of zinc-imidazole reverse-stained gels. Many staining effects observed when gels containing electrophoretically separated biopolymers are subjected to zinc-imidazole stains have been rationalized. The reverse-staining method has been vastly generalized, now allowing the detection of proteins and glycolipids as well as complexes of these macromolecules in native gels. We demonstrate the application of the reverse-staining technique in situations where Coomassie blue or silver staining was inappropriate or failed to produce detection of the species of interest. The present generalization of the reverse-staining method facilitated the characterization of biomacromolecular interaction partners in mixtures of bacterial glycolipids and human tears.

Bacteria↗

PubMed1998

Multiple locations of the rDNA sites in holocentric chromosomes of Rhynchospora (Cyperaceae).

Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S-5.8S-26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4-8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.

Chromosome Mapping↗

PubMed1998

PAF levels in saliva are regulated by inflammatory cells.

Platelet activating factor (PAF), a powerful inflammatory phospholipid mediator, has been detected in normal human saliva and found to be increased in periodontitis. The cellular source of PAF in saliva is controversial although several data suggest an origin related to the presence of inflammatory cells. PAF levels in biological fluids are regulated by PAF-producing cells and by the PAF-degrading acetylhydrolase. Although in normal human saliva acetylhydrolase activity is very low, no information is available on the levels of this enzyme in inflammatory conditions of the mouth. The aim of our study was to assess the contribution of inflammatory cells to the levels of PAF in saliva in normal subjects and in patients with periodontitis. PAF was measured by radioimmunoassay (RIA) in mixed uncentrifuged saliva and in cell-free saliva from healthy subjects, before and after tooth brushing, and in patients with periodontitis. In healthy subjects PAF levels were significantly higher in whole saliva than in centifuged saliva (1.51 +/- 0.22 vs. 0.92 +/- 0.04 ng/ml, p < 0.0039). A significant increase in the amount of PAF was detected in whole saliva, but not in centifuged saliva, 2 h after tooth brushing. In patients with periodontitis PAF levels were not different from those of healthy individuals when using centrifuged saliva but were significantly higher when using whole, uncentrifuged saliva. Exogenous radiolabelled PAF was degraded much more rapidly by the saliva of periodontitis patients than by that of normal subjects. In conclusion, our study shows that inflammatory cells regulate the levels of PAF in saliva contributing to its production and degradation. The differential degradation of PAF in normal and inflammatory saliva highlights the absolute need of a series of methodological precautions when performing studies on salivary PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed1998

Improved hematoxylin staining for algal cytogenetics.

The aceto-iron hematoxylin method of Wittmann for algal chromosomes was improved by replacing the chloral hydrate and slide heating steps with 5 N HCl hydrolysis. Squashing of the unstained material under the coverslip followed by coverslip removal and air drying allowed rapid and more homogeneous staining. Additional procedures were developed to make the method easier and quicker. Good results were obtained for all algal species analyzed. Pit-connections of red algae were also clearly differentiated.

Acetates↗

PubMed1998

Carotid endarterectomy and contralateral internal carotid artery occlusion: perioperative risks and long-term stroke and survival rates.

BACKGROUND: The aim of this article was to analyze the perioperative mortality and stroke risk rates and late benefits of carotid endarterectomy (CE) contralateral to an occluded internal carotid artery (ICA), on the basis of our surgical experience from July 1990 to June 1996. METHODS: In 57 (14.7%) of 336 patients undergoing 388 CEs, the contralateral ICA was occluded (group I). All operations were performed under general anesthesia with selective shunting based on electroencephalographic criteria. Shunting was used in 36 (63.1%) of 57 revascularizations in group I and 47 (14.2%) of 331 operations performed on the remaining 279 patients with patent contralateral ICAs (group II) (p < 0.001). RESULTS: Perioperative strokes occurred in two patients (3.5%) in group I and three patients (1%) in group II (difference not significant). The only perioperative death, which occurred in one patient (1.7%) in group I, was the result of a perioperative stroke; two patients (0.7%) in group II died within 30 days of operation (difference not significant). Life-table cumulative stroke-free rates at 1, 3, and 5 years were 95%, 95%, 95% in group I and 98.8%, 98.2%, and 98.2% in group II, respectively (p = 0.272). Life-table cumulative survival rates at 1, 3, and 5 years were 97.5%, 94.2%, and 78.1% in group I and 99.2%, 94.8%, and 71.7% in group II, respectively (p = 0.306). CONCLUSIONS: The results of this analysis indicate that CE contralateral to an occluded ICA can be performed with acceptable perioperative mortality and stroke risk rates and late stroke-free and survival rates comparable to those seen in patients without contralateral ICA occlusion who have undergone operation. Nevertheless, we think it is misleading to imply that the risks of operating on the two groups are the same. Moreover, because no late stroke-related death occurred in patients with contralateral ICA occlusion, it would appear that superior late stroke-free rates did not translate into a prolonged survival advantage.

Aged↗

PubMed1997

Results of a European randomized trial of Etanidazole combined with radiotherapy in head and neck carcinomas.

PURPOSE: The aim of the study was to evaluate the efficacy and toxicity of Etanidazole, a hypoxic cell sensitizer, combined with radiotherapy in the treatment of head and neck squamous cell carcinoma. METHODS AND MATERIALS: A total of 374 patients from 27 European centers were included in this trial between 1987 and 1990. Treatment was either conventional radiotherapy alone (between 66 Gy in 33 fractions and 74 Gy in 37 fractions, 5 fractions per week), or the same radiotherapy dose plus Etanidazole 2 g/m2, three times weekly for 17 doses. A minimization procedure, balancing for center, site, and T stage (T1-T3 vs. T4) was used for randomization. RESULTS: Among the 187 patients in the Etanidazole group, 82% received at least 14 doses of the drug. Compliance to the radiotherapy protocol was 92% in the Etanidazole group and 88% in the control group; the main cause of deviation was acute toxicity, which was observed at an equal rate in the two treatment groups. Fifty-two cases of Grade 1 to 3 peripheral neuropathy were observed in the Etanidazole group vs. 5 cases, all of Grade 1, in the control group (p < 0.001). The 2-year actuarial loco-regional control rates were 53% in the Etanidazole group and 53% in the control group (p = 0.93), and the overall 2-year survival rates were 54% in each group (p = 0.99). CONCLUSION: Adding Etanidazole to conventional radiotherapy did not afford any benefit for patients with head and neck carcinoma. This study failed to confirm the hypothesis of a benefit for patients with N0-N1 disease, which had been suggested by the results of a previous study (10).

Adult↗

PubMed1997

Social and economic impact of neurotoxicity in hazardous waste workers in Lenoir, North Carolina.

A detailed study of workers at a hazardous waste incinerator in Lenoir, North Carolina, revealed significant financial losses resulting from health problems caused by the incinerator. The losses included approximately $3 million for 3 years of medical care for 28 workers employed at the incinerator. Future wage losses for exposed workers were projected to be from $14 million to $15 million. Loss of the incinerator as a viable employment base was a significant blow to the local economy. Third-party payers of medical costs, government and private, were also at risk of financial loss. Workers' compensation benefits ranging from $6500 to $274,000 per person were paid by insurance companies to some workers; however, these benefits did not always cover the medical expenses incurred. As a result of their illnesses, 11 of the 28 workers (39%) had to sell or give up their homes, 8 workers (36%) lost their vehicles, 19 workers (68%) began to receive Social Security Disability payments, and 11 workers (39%) obtained food stamps. One worker not included in these figures died 3 years after he settled with the state workers' compensation program. Five of the 28 interviewed workers continue to work in spite of continuing health problems. The 23 workers who cannot work will have estimated lifetime medical expenses of $25.4 million.

Air Pollutants, Occupational↗