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Biomedical subjects

D Guerra

Publications and source records attributed to D Guerra.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Weaver syndrome. 1st case reported in Venezuela].

A 2 years and 9 months old female patient, with the diagnosis of Weaver syndrome is reported. The proband presents persistent pre and post-natal overgrowth, asynchronic advanced bone age, particular facies, (macrocephaly, ocular hypertelorism, micrognathia, large ears), bilateral widening of the distal femoral metaphysis, bilateral tibia vara, prominent fetal fingerpads, clinodactyly, development delay, low pitched and hoarse cry, nonspecific cortical atrophy, dilation of the ventricles and vermix hypoplasia. The differential diagnosis with other overgrowth syndromes is discussed. The possibility of uniparental disomy and genetic imprinting as the basic genetic defect in the Weaver syndrome is suggested. The patient reported here appears to be the first case in the Venezuelan literature.

Abnormalities, Multiple↗
PubMed1997

[Clinico-epidemiologic study of microtia].

Microtia is a congenital malformation characterized by total or partial absence of the whole auricle or any of its components, varying from a small auricle to the total absence (anotia). There may be associated atresia of the external auditory meatus. The frequency varies in different parts of the world between 0.4 and 5.5/10,000 newborns. In this paper we report the clinical and epidemiological characterization of this congenital malformation in a sample of 97.759 neonates born at the Ruíz y Páez Hospital in Ciudad Bolivar, Venezuela, between April 1978 and December 1994. A total of 38 patients with microtia were identified. The global frequency was 3.8 per 10,000/newborns. In 47.4% of the patients microtia was an isolated malformation and in 52.6% was associated to other malformations. Sixty three percent of the affected were males. The unilateral form was present in 81.5% of the cases, more frequently on the right side. The annual frequency of the defect was stable over the studied years. The clinical classification of the cases with associated malformations allowed us to establish that 18.4% of the cases correspond to developmental fields defects, associated to preauricular dimples and/or tags, 7.8% were cases of the facio-auriculo-vertebral spectrum and in 15.7% the microtia was part of a monogenic or chromosomal syndrome. In 10.5% it was not possible to define any etiological or pathogenic mechanism. The frequency obtained in this study for microtia shows intermediate values when compared with others reports from Latin America.

Abnormalities, Multiple↗
PubMed1996

Retrospective study of the correlation between the DNA repair protein alkyltransferase and survival of brain tumor patients treated with carmustine.

We tested the hypothesis that the level of the DNA repair protein O6-alkylguanine-DNA alkyltransferase in brain tumors was correlated with resistance to carmustine (BCNU) chemotherapy. Alkyltransferase levels in individual cells in sections from 167 primary brain tumors treated with BCNU were quantitated with an immunofluorescence assay using monoclonal antibodies against human alkyltransferase. Patients with high levels of alkyltransferase had shorter time to treatment failure (P = 0.05) and death (P = 0.004) and a death rate 1.7 times greater than patients with low alkyltransferase levels. Furthermore, the size of the subpopulation of cells with high levels of alkyltransferase was correlated directly with drug resistance. For all tumors the variables most closely correlated with survival, in order of importance, were age, tumor grade, and alkyltransferase levels. For glioblastoma multiforme, survival was more strongly correlated with alkyltransferase levels than with age. These results should encourage prospective studies to evaluate alkyltransferase levels as a method, for identifying brain tumor patients with the best likelihood of response to BCNU chemotherapy.

Antibodies, Monoclonal↗
PubMed1996

The European study of assisted reproduction families: family functioning and child development.

Findings are presented of a European study (conducted in the UK, Italy, Spain and The Netherlands) of family relationships and the social and emotional development of children in families created as a result of the two most widely used reproductive technologies, in-vitro fertilization (IVF) and donor insemination (DI), in comparison with control groups of families with naturally conceived child and adoptive families. Mothers of children conceived by assisted reproduction expressed greater warmth towards their child, were more emotionally involved with their child, interacted more with their child and reported less stress associated with parenting than mothers who conceived their child naturally. Similarly, assisted reproduction fathers were found to interact more with their child and to contribute more to parenting than fathers with a naturally conceived child. With respect to the children themselves, no group differences were found for either the presence of psychological disorder or for children's perceptions of the quality of family relationships. The findings relating to the quality of parenting and the socio-emotional development of the children were similar in each of the four countries studied.

Adoption↗
PubMed1996

Ultrastructural identification of a membrane-like structure on the surface of normal articular cartilage.

Cytochemical and immunocytochemical approaches have been applied to the study of the surface of articular cartilage in humans, bovine and rats. Specimens were fixed in situ or soon after bioptic sampling with chemicals able to preserve and visualize proteins (glutaraldehyde, tannic acid), lipids (osmium tetroxide, malachite green, uranyl acetate) and proteoglycans (toluidine blue O, cuprolinic blue, cetyl pyridinium chloride). Mixtures of reagents were also used. Oriented serial thin sections were observed as such or after treatment with chemicals (chloroform-methanol, Triton X 100) or enzymes (chondroitinases, hyaluronidases, trypsin). Hyaluronan was detected by the use of glial-hyaluronate-binding-protein and antibodies against it. High concentration of osmium tetroxide or fixatives containing markers for lipid or for proteoglycans revealed that the surface of the articular cartilage, in all animal species examined, was covered by mono-multilayered discontinuous three-laminar sheets, which could be partly removed by chloroform-methanol and Triton X 100, were sensitive to hyaluronidase, chondroitinase and trypsin, and were immunopositive for hyaluronan. Each three-laminar sheet was 12-14 nm thick, was always separated from the cartilage itself and could be easily displaced. It is proposed that the surface of normal articular cartilage is covered by a discontinuous mono/multilayered pseudo-membrane, that can be better preserved by fixatives injected into the joint cavity and seems to consist of phospholipids, glycosaminoglycans and proteins. This membrane-like structure might have a protecting role in preventing direct contacts between the articular cartilage and toxic agents present in the synovial fluid and/or exert a lubricating effect within the articular joint.

Animals↗
PubMed1996

[Gastric volvulus in childhood].

Gastric volvulus in children might be observed both as an acute form, characterized by gastric necrosis with sudden perforation and patient's death and as an idiopathic or chronic form with a less severe insurgence that causes epigastric pain, vomit and gastric distension. The latter could resolve spontaneously but recurs frequently. The acute form rises in newborns and toddlers and is often associated with a diaphragmatic defect; the idiopathic forms are correlated on the opposite to a fixation deficit of the stomach which is held in place by the gastro-colic, gastro-hepatic, gastro phrenic and gastro-splenic ligaments. Since a diagnostic mistake could cause the patient's death gastric volvulus must be carefully considered as a possible cause of acute epigastric pain with vomit. In the two forms surgical therapy is mandatory for the simultaneous correction of both the anatomical defects of gastric fixation and malposition and the diaphragmatic ones. The case presented is an example of an acute gastric volvulus in a 2-year-old male child affected by a diaphragmatic defect The peculiar aspect of this case consists in the age of arousal being more usual in an earlier age An appropriate surgical treatment has permitted the patient's recovery.

Diaphragm↗
PubMed1995

O6-methylguanine-DNA methyltransferase in human brain tumors detected by activity assay and monoclonal antibodies.

O6-methylguanine-DNA methyltransferase (MGMT) activity was measured in 68 tissue samples taken from brain. A wide range in activity among samples was observed, with all nonmalignant samples showing transferase activity (Mer+) but approximately 15% of WHO grade II low-grade astrocytomas and WHO grade IV glioblastoma multiformes lacking activity (Mer-). On average, astrocytomas and glioblastomas showed less transferase activity than either nonmalignant tissue or meningiomas. Monoclonal antibodies specific for MGMT showed both cytoplasmic and nuclear staining of Mer+ brain tumor cells in culture but no staining of Mer- cells in culture. In pathology specimens from anaplastic astrocytomas, glioblastoma multiformes, and meningiomas, antibody staining revealed both cytoplasmic and nuclear MGMT, while one sample showed little or no MGMT-specific staining. These results help explain why nitrosoureas have been among the most successful agents in treatment of brain tumors and indicate the subcellular localization for the repair activity, which may be relevant to nitrosourea resistance.

Antibodies, Monoclonal↗
PubMed1994

Ultrastructural and immunocytochemical study on normal human palmar aponeuroses.

BACKGROUND: Human palmar aponeurosis can be affected by a fibrotic process whose aetiopathology is unknown. As the organization of that normal tissue has not been completely investigated, the aim of the present study was to define the ultrastructure of the aponeurosis in order to better understand its biology and behaviour in pathology. METHODS: Bioptic samples from normal subjects of different ages were analysed by optical and electron microscopy and by immunocytochemistry. RESULTS: The aponeurotic branches consisted of thick, almost parallel collagen bundles containing columns of prominent cells, characterized by long cytoplasmic projections. Cells did not change in number and distribution with age and appeared longer and slighter in the old than in the young subjects. They exhibited plasma membrane almost completely decorated by pinocytic vesicles, intracytoplasmic bundles of thin filaments with zonal thickenings close to the cell membrane, and well-developed subcellular structures. Cells expressed smooth muscle cell alpha-actin, as revealed by immunostaining. The external surface of the plasma membrane was underlined by a discontinuous basement membrane-like structure and by a thick coat of interwoven filaments, highly positive to hyaluronan-recognizing antibodies. Immunocytochemical analyses revealed that collagen fibrils were positive for collagen types I, III, and VI and that elastin fiber composition was rather complex. CONCLUSIONS: Independently of the age, normal palmar aponeurotic cells show peculiar morphological features and peculiar cell-matrix interactions, very likely mediated by hyaluronan. These findings indicate that normal aponeurotic cells cannot be regarded as typical tenocytes and suggest the need for a better definition of their phenotype in order to understand their behaviour in pathological processes.

Adult↗
PubMed1993

A clinical, ultrastructural and immunochemical study of Dupuytren's disease.

Aponeurotic tissue from seven normal subjects and from apparently unaffected branches, nodules and cords of 16 Dupuytren's patients were compared. Control tissue was characterized by polymorphous cells, showing cytoplasmic microfilament bundles, numerous pinocytic vesicles, basement membrane-like structures, and a thick coat of interwoven filaments, and by type I- and III-positive heterogeneous collagen fibrils, fibronectin, vitronectin, decorin and proteoglycans. The clinically normal branches consisted of fibroblast-like cells, small type III-highly positive collagen fibrils, fibronectin and proteoglycans. Nodules and fibrotic cords contained fibroblast-like cells, type I and III collagen, fibronectin and proteoglycans. Myofibroblast-like cells in only five out of 16 patients were present. There was no relation between clinical stage and structural alterations; the whole aponeurosis always seemed to be involved; cord retraction would seem to depend on the interactions among fibroblast-like cells and matrix components and among matrix macromolecules themselves.

Adolescent↗
PubMed1992

Aging of the human synovium: an in vivo and ex vivo morphological study.

Age-associated changes of the human synovium have been investigated by microarthroscopy, optical and electron microscopy, immunohistochemistry, and cytochemistry. The knee joints of nineteen 15- to 56-year-old subjects, classified as normal by inspection, were carefully examined by microarthroscopy; small synovial tissue biopsy specimens from both the suprapatellar pouch and the medial tibiofemoral gutter were taken. Microarthroscopy showed that the villi were more numerous and the vascular network and cell distribution and profiles less regular in aged individuals. These data were confirmed by scanning electron microscopy, which also showed large areas of the synovial surface devoid of cells and collagen bundles in contact with the joint cavity in aged subjects. Light and transmission electron microscopy confirmed these data and allowed evaluation of the number, distribution, shape, and internal organization of cells as well as the distribution of vessels and the organization of the extracellular matrix in the full thickness of the synovium (down to 2 mm). Particular attention was paid to synovial lining cells, among which three main phenotypes could be recognized: synthetic type (present at all ages and hypertrophied in aged subjects), macrophagelike (increasing with age), and fibroblastlike. Collagen increased with age. Further studies are needed for comprehensive understanding of age-associated changes in the human synovium.

Adolescent↗
PubMed1992

[Correlation between Dupuytren's disease and arcus senilis: is dyslipidemia a common etiopathological factor?].

Because of the frequent presence of corneal arcus senilis in patients affected by Dupuytren's disease in order to evaluate this association, the authors conducted a biomicroscopic examination of the cornea in 336 patients treated surgically for Dupuytren's disease, at the Hand Surgery Unit of the University of Modena from November 1985 to December 1989. They observed corneal arcus senilis in 259 patients, i.e. in 77.1% of patients with Dupuytren's disease. Due to the statistically significant correlation between arcus senilis and hyperlipidemia as reported by Tschetter (1980) and Felder (1981), the Authors collected a blood sample from all 336 patients to evaluate serum cholesterol and tryglicerides. This study revealed a dyslipidemia in 54.8% of patients with Dupuytren's disease and in 60.2% of patients suffering from both Dupuytren's disease and arcus senilis. Because of the high frequency of dislipidemia in patients with Dupuytren's disease and arcus senilis, which are apparently two well-distinguished disease, the authors suggest that a lipid disorder may be a common aetiopathogenic factor. In particular, in favour of the possible role of hyperlipidemia in Dupuytren's disease, Electron Microscope Studies revealed lipid inclusions within fibroblasts and in the extracellular connective tissue of all pathologic palmar aponeurosis from 11 patients with Dupuytren's disease: these lipid inclusions were never seen in the normal aponeurosis taken from 5 control patients treated for traumatic palmar injuries.

Adult↗
PubMed1991

[A multicenter study of the breaking of the smoking habit with nicotine chewing gum in health personnel].

BACKGROUND: The health professionals have a leading role in the reduction of the smoking prevalence. Spain has one of the big rate of "per capita" tobacco consumption in the world, and the Spanish doctors have the biggest prevalence of smokers among their colleagues from the EEC countries. METHODS: The effectiveness of a stop smoking programme in health care professionals was evaluated. This programme combined group therapy, nicotine chewing gum and behavioural assistance through the evaluation of CO contained in expired breath; and it is being applied with good results between the smokers of general population in Spain. A total of 211 voluntary smokers working in Spanish six general hospitals were treated, from those 149 (71%) were physicians and nurses (PS) and 62 (29%) others professionals without sanitary responsibilities (PNA). RESULTS: At one year follow-up, 64 (30%) were not smoking, and the P.S. had a higher rate of give up than the PNA (p less than 0.05). Specifically the women of P.S. obtained a greater issue than the women of PNA (p less than 0.05). Both, nicotine chewing gum and behavioural assistance were as effective as usual in smoking cessation programme like this, in our country. CONCLUSIONS: Although the outcome is lower than the obtained with the same approaches in smokers from general population, the better results of the PS than the PNA imply a good change of attitude of them. Specially the women PS obtained a big success, and this is outstanding in this group with a great prevalence of smokers, increasing in the recent years. The subjects who give up smoking increased their corporal weight less than the observed in smokers of the general population, who also give up with this treatment.

Adult↗
PubMed1991

Effect of subject expectancy on the THC intoxication and disposition from smoked hashish cigarettes.

Subject expectancy on cannabis effects was assessed in a balanced-placebo study in experienced consumers who smoked cigarettes containing hashish (200 mg hashish with 11.5% THC per 1 g tobacco cigarette) (n = 24) or placebo (n = 24). Although statistically significant differences were not found between subjects who received the drug with positive or negative expectancy, a tendency toward more marked subjective effects was shown in subjects who expected and received the drug. This trend was supported by the significant difference observed in the mean AUC0-25 of the heart rate between subjects who smoked hashish with positive or negative expectancies. In subjects who received hashish, the sum AUC0-205 of THC and COOH-THC of those who expected the drug was greater than in those who did not expect it (p less than 0.05). The ratio THC/COOH-THC AUC0-205 was lower in those with positive expectancy than in those with negative expectancy (p less than 0.02). An increased metabolism of THC was shown in subjects with positive expectancy. Positive expectancy induced powerful subjective effects in the absence of active THC. Expectancy appeared to influence smoking behavior, as seen in higher plasma levels of cannabinoids for the group who received the drug.

Adult↗
PubMed1991

Epidemiological and structural findings supporting the fibromatous origin of dorsal knuckle pads.

Epidemiological, optical and electron microscopical findings suggest that dorsal knuckle pads and Dupuytren's disease are fibrosing disorders with common features. In all cases examined, knuckle pads were always associated with Dupuytren's contracture and, in a significant number of cases, with bilateral Dupuytren's contracture. In a statistically significant number of patients with knuckle pads, Ledderhose's and Peyronie's diseases were also present (P less than 0.001). Optical and electron microscopical studies showed that cell types and extracellular matrix were identical in knuckle pads and Dupuytren's nodules in different patients.

Adult↗
PubMed1991

Treatment of murine candidosis and cryptococcosis with a unilamellar liposomal amphotericin B formulation (AmBisome).

This investigation examined the therapeutic efficacy of AmBisome, a unilamellar (55-75 nm) liposome amphotericin B preparation with a murine LD50 by the intravenous route of greater than 175 mg/kg amphotericin B. Both fungal burden and survival were used to evaluate the drug's efficacy against murine candidosis and cryptococcosis. Single and multiple dose intravenous treatment with AmBisome (2.5, 5.0 and 10.0 mg/kg) reduced the colony forming units/mg kidney in candida-infected mice by 99% and improved survival by at least 40% relative to untreated control mice. Repeated intravenous dosing of candida-infected mice with equivalent amounts (0.75 mg/kg) of conventional amphotericin B (Fungizone) or AmBisome showed comparable reduction of yeasts in the kidneys. When mice were infected systemically with Cryptococcus neoformans, all but one of the 30 mice given AmBisome (5.0, 7.5 or 10.0 mg/kg) survived until the experiment was terminated 35 days after infection. Liver and spleen cultures from AmBisome-treated mice were negative for fungal growth. All the mice given conventional amphotericin B intraperitoneally at 4.5 mg/kg survived and cleared the infection from the livers although some of the mice had infected spleens. The percentage of cultured brains free of cryptococcus was 89% following treatment with 10.0 mg/kg AmBisome, and 80% with 4.5 mg/kg conventional drug. These preclinical studies of systemic candidosis and cryptococcosis demonstrate comparable efficacy of AmBisome and conventional amphotericin B at low doses and improved efficacy with AmBisome at doses higher than can be safely administered of the conventional drug.

Amphotericin B↗
PubMed1990

[Coexistence of myelofibrosis and collagen diseases].

Hematologic abnormalities are common in association with collagen diseases, specially Systemic Lupus Erythematosus and include anemia, neutropenia, thrombocytopenia with alterations in lymphocyte subpopulations. On the other hand, patients with unexplained fibrosis of the bone marrow (the syndrome of idiopathic myelofibrosis or primary myelofibrosis) have clinical and laboratory evidence of immunologic dysfunction. Clinical findings include the presence of arthritis, vasculitis and erythema nodosum. Laboratory abnormalities include the presence of circulating immune complexes, antinuclear antibodies, positive direct Coombs test, elevated latex fixation and a circulating lupus type anticoagulant. Total hemolytic complement markedly depressed has also been reported. These data suggest that immunologic mechanisms associated with activation of the complement system play an important role in the disease process of some patients with agnogenic myeloid metaplasia with myelofibrosis. A review of the literature revealed that myelofibrosis occurring in the setting of collagen diseases is rare. However, a role for immunologic factors in the pathogenesis of myelofibrosis is also supported by the patients with coincident well defined collagen disease and myelofibrosis. In this report, we present two patients with such an association. Case 1 was a 58-year-old male with a two year duration history of rheumatic arthritis. He had bone erosions on hands, splenomegaly and myelofibrosis. Rheumatoid factor (latex) was positive: 1:2560. He had positive LE cells and hypocomplementemia: 37 CH50/ml (NV 70-150). The patient did not meet criteria for SLE. Case 2 was a 36-year-old female admitted because of dyspnea and fever. Diagnosis of myeloid metaplasia with myelofibrosis and progressive systemic sclerosis had been made four years before hand.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Developmental effects of modifiers of the vg mutant in Drosophila melanogaster.

An analysis of the modifiers affecting the expression of the vg gene was performed. We selected for weak and strong expression of the vg mutant in F2 segregating populations obtained by crossing a vestigial stock with an Oregon laboratory stock (O) and with a wild strain (B) captured near Bologna, Italy. The selection for enlarged wings was more effective in the vg B population where wild wings appeared from the 10th generation. The assay of the three major chromosomes showed that the modifiers are located on chromosomes 2 and 3. The mutant imaginal disc cell death phenotype is evident in vg/vg strains that have a wild-type wing phenotype. It is suggested that the selected modifiers do not prevent cell death but induce regenerative growth.

Animals↗