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D Castro

Publications and source records attributed to D Castro.

At least 73 records · Page 4Linked to original sources
PubMed1984

Genetic mapping of Vibrio cholerae enterotoxin structural genes.

The structural genes which constitute the cholera toxin operon, ctxAB, were genetically mapped in the Vibrio cholerae El Tor strain RV79. This strain of V. cholerae contains two copies of the ctx operon located on a 7-kilobase-pair tandemly duplicated region. We began by isolating a vibriophage VcA1 insertion mutation in one of the two ctxA genes located in this region. The mutant carrying this ctxA::VcA1 insertion, DC24, was converted to a VcA1-facilitated donor by introduction of the conjugal plasmid pSJ15, which carries an inserted copy of a defective VcA1-like prophage. The donor characteristics of DC24(pSJ15) indicated that the ctxA::VcA1 insertion mutation was near the trp region of the V. cholerae chromosome. Subsequent RV79 three-factor crosses were performed between VcA1-facilitated donors and recipient strains carrying one of two structural gene mutations in ctx, either delta ctxA23P Kmr or delta ctx-7922. The former was constructed by an in vivo marker exchange procedure and could be scored either by its kanamycin resistance phenotype or by its lack of DNA sequences homologous to the ctxA region. The delta ctx-7922 mutation is a total deletion of both ctx copies of strain RV79. The three-factor cross data strongly suggest that the two ctx loci of RV79 map between the nal and his genes of V. cholerae in the trp nal his linkage group. Physical analysis and heterologous crosses between an RV79 El Tor donor and a 569B classical recipient indicates that one of the two 569B ctx operon copies maps in the same region as the RV79 ctx loci (i.e., linked to nal). Together with previously published observations, these data show that the ctx structural genes are not closely linked to other genes known to affect toxin production in V. cholerae.

Cholera Toxin↗
PubMed1982

A new method of dosimetry-a study of comparative laser-induced tissue damage.

The use of lasers in medicine and surgery has increased slowly-its effectiveness based on trial-and-error clinical experience. Very little comprehensive data has been published that scientifically presents dosage, energy, absorption, and comparisons between types of lasers. Our laboratory has developed a method for taking the guesswork out of laser dosage using scientific data to optimize therapy and give reproducible responses. Experiments were conducted using an argon laser, a neodymium: YAG laser, and a broad-band infrared light source. This preliminary study uses a beam scan technique, which for the first time permits accurate measurement of the laser intensity incident on tissue. Therefore, this protocol allows the standardization of dosage measurements with good experimental reproducibility in biological models. By using this accurate method of measuring the intensity delivered to pigskin, we are able to reproduce for the first time similar histological damage with the different energy sources.

Animals↗
PubMedDate not supplied

MR-guided aspiration cytology in the head and neck at high field strength.

Published reports of magnetic resonance (MR)-guided needle biopsy have involved low- and mid-field-strength systems because of the concern of needle artifact and risk of increased needle torque at higher field strengths. To the authors' knowledge, this is the first report of a high-field-strength (1.5-T) system used to guide aspiration cytology in the head and neck in a patient. The procedure was successfully accomplished without additional needle torque or substantial increase in image artifact relative to lower-field-strength imaging.

Biopsy, Needle↗
PubMedDate not supplied

Necrotizing lesions of soft tissues: a review.

Necrotizing lesions of the soft tissues are grave entities not infrequently seen in daily surgical practice. They may occur with epidemic proportions after natural disasters, representing a serious challenge to the surgeon since they are characteristically associated with high mortality rates unless an early diagnosis is made and prompt aggressive surgical management is initiated. Necrotizing fasciitis is the currently accepted generic term to encompass into a single category the diverse syndromes of progressive gangrenous infections of the skin and subcutaneous tissues. Necrotizing fasciitis must be viewed as a clinical entity rather than a specific type of infection: it is a clinical infection most commonly caused by a mixed aerobic/anaerobic synergistic polymicrobial combination. Zygomycetes may appear as major causal organisms (mucormycosis) and they should be actively searched for. Initial diagnosis of necrotizing fasciitis is established through the characteristic physical signs. Gram stain, and, in some doubtful cases, through frozen-section tissue biopsy. Aggressive and urgent radical debridement is the key to survival, combined with wide-spectrum antibiotic therapy.

Fasciitis↗
PubMedDate not supplied

Necrotizing soft tissue lesions after a volcanic cataclysm.

A volcanic cataclysm of major proportions, the fourth largest in terms of total casualties in the history of mankind, wiped out the town of Armero, Colombia, in 1985 resulting in over 23,000 deaths and 4,500 wounded. Among the hundreds of survivors who were transferred to hospitals in the capital city of Bogotá, there was as overwhelming number who developed necrotizing fasciitis. These patients constitute, perhaps, the single largest group of this type of lesions in the recorded literature. Thirty-eight patients with well established necrotizing fasciitis were identified at 4 selected hospitals in Bogotá; 8 of them presented with zygomycetic infection (mucormycosis), a highly lethal entity. Many additional cases were treated at other hospitals in Bogotá and several cities in Colombia. The main clinical features of these 38 patients affected by necrotizing fasciitis are reviewed, with special emphasis on the patients with mucormycosis. Patients with necrotizing fasciitis had an overall mortality rate of 47.7%; patients with mucormycosis, 80%. A plea is made for an early diagnosis, utilizing tissue sampling and microbiological studies, so that prompt and radical treatment can be instituted. This is especially pertinent in situations of natural disasters resulting in massive numbers of casualties and seriously injured survivors.

Amputation, Surgical↗
PubMedDate not supplied

[Intestinal amebiasis in Antofagasta, Chile].

In January 1989--December 1991 period we verified 35 cases of symptomatic intestinal amebiasis in Antofagasta, the main city of the North of Chile. Out of the total number of studied patients 23 were adults (77.1% males and 22.9% females) and all of them were permanent residents of Antofagasta. E.histolytica was frequently detected in association with other parasites and/or commensals, and observed alone in only seven cases. The clinical and epidemiological aspects of these 35 cases are discussed.

Adolescent↗
PubMedDate not supplied

[Endoscopic resection in early gastric cancer].

Development of therapeutic endoscopy has permitted the treatment of early gastric cancer (EGC) in its different macroscopic forms. In this paper we present 9 cases of EGC treated endoscopically in our Institution. We describe the criteria we follow to perform this procedure. The patients selected were of advanced age and high surgical risk. Seven cases were macroscopically Type I and two were Type IIa. According to localization six were proximal tumors (body and fundus) and three were located in the antrum. Six of the nine patients are alive after resection, one more than 6 years and 3 more than 3 years. Three patients died of ailments no related to cancer.

Aged↗
PubMedDate not supplied

[Histologic study of Helicobacter pylori in 265 consecutive gastric biopsies].

We evaluated 265 consecutive endoscopic gastric biopsies of subjects attending the gastric cancer mass survey that is taken place in the State of Tachira, Venezuela. They were 152 males and 113 females between 18 and 70 years of age. We established the prevalence of Helicobacter pylori in relation with histologic diagnosis and location of the lesions in the stomach. We performed hematoxylin eosin, Giemsa and Gimenez stains. The bacteria was identified in chronic non atrophic gastritis in 81% of the cases, in 76% of erosive gastritis, in 72% of gastric ulcers, in 36% of chronic atrophic gastritis and in 16% of neoplastic tissues. Helicobacter pylori was found in 82% of antral biopsies, and in 9% of the body, 7% of the fundus and 2% of the cardiac biopsies. From the total of 265 biopsies HP was positive in 172. The prevalence of this bacteria was 69.9% in this investigation.

Adolescent↗
PubMedDate not supplied

[Psychology and cancer: role of rationalization in cancerous disease of unfavorable prognosis (apropos of a clinical case)].

This text intends to tackle one of the aspects of psychosomatic interactions in cancer: the patient's irrational cognitions related to his trouble. The authors design as cognitive process (CP) the mental work implying the production and the evolution of personal cognitions bound to a personal event. In cancer, CP often drives the subject to adopt irrational points of view concerning his disease, which onset is readily described as a consequence of significant life events; in such explanations, the part of hazard is excluded. The authors suggest that spontaneous CP may be useful helping the patient to avoid strong depressive affects, to alleviate feelings of anger or despair and to improve self-esteem threatened by the illness. The authors consider that using CP concept may be an accurate tool in psychotherapy of patients suffering from cancer. Therapeutic strategies may tend to favour the CP development so that the subject's conceptions stabilize on an ego-syntonic level.

Attitude to Death↗
PubMedDate not supplied

[Gastric cancer in hyperplasia polyps].

We present 3 cases of Early Gastric Cancer in 82 Hyperplastic Polyps (HP) resected endoscopically (3.6%) during the years 1985 to 1989, at the GI Cancer Center "Dr. Luis E. Anderson", San Cristobal, Venezuela. The diagnosis criteria followed were those of Nakamura, T and Nagayo T. This paper shows the possibility of malignant changes of these lesions, advising endoscopic resection of HP as a mean of treatment and in order to make a complete study of the polyps. We compare our data with existing bibliography, finding similitude in results.

Aged↗
PubMedDate not supplied

[Metastasis to lymph nodes in early gastric cancer].

The presence of metastasis in lymph nodes is one of the most important aspects to be evaluated in Early Gastric Cancer (EGC). In this paper we analyze the presence of that kind of metastasis in 70 EGC, in 66 patients studied in our Institute and surgically treated at the Central Hospital of San Cristobal. We found 3 cases with metastasis to perigastric (regional) lymph nodes (N1) and one case with extra perigastric lymph nodes metastasis (N3), that signify 5.7% of the total of all cases. We established the relationship of these metastasis and the following variables: macroscopic type, localization, size, depth of invasion within the gastric wall and the histological variety of the lesions. We found that the type IIa + IIc, the lesions located in the fundus, bigger that 3 cm, with invasion reaching the submucosa and histological differentiated (intestinal type), were the most important characteristics related with the presence of metastasis to the lymph nodes in our EGC.

Humans↗
PubMedDate not supplied

[Endoscopic polypectomy of the upper digestive tract].

From 1985 to 1987 we performed 82 endoscopic polipectomies in 80 patients. In this paper we refer the technics, epidemiological data and macro and microscopical findings of the resected specimens. Two patients with gastric cancer were treated in this way, these patients had formal surgical contraindication. In two patients in whom the endoscopic biopsies could not render a definitive diagnosis (cancer or atypical epithelium), the study of the resected tumor permitted the diagnosis of atypical epithelium, so two gastrectomies were avoided. Among our resected lesions we found 55 of inflammatory type, 6 adenomas and 7 atypical epithelium. We consider that this is a useful method for the diagnosis and treatment of some elevated lesions. Although this is not the treatment of choice for the elevated early cancer, it could be used to treat cancerous tumors in patients with high surgical risk.

Adult↗
PubMedDate not supplied

[Asymptomatic stomach ulcer].

The purpose of this paper is to evaluate the frequency and some of the clinical and epidemiological characteristics of asymptomatic gastric ulcer, found in persons who attend the Center for Control of Gastrointestinal Cancer of San Cristóbal, Venezuela, as part of a gastric cancer mass screening program. 350 patients with active peptic ulcer were found, 176 duodenal and 174 gastric, diagnosed by means of endoscopy. Of the patients with gastric ulcers, 67 (38.5%) had no symptoms. This group of asymptomatic patients were analyzed regarding age, sex, place of residence, type of work and also the location of the ulcer and the histology. We conclude that this entity is frequent in our region that it is associated with agricultural workers and house wives. It is necessary to continue a prospective periodical evaluation of these patients in order to understand the natural history of the entity.

Adult↗
PubMedDate not supplied

[Macroscopic and histopathological aspects of atypical gastric epithelium].

Atypical Epithelium is a localized lesion, which has histological and macroscopic findings similar to gastric cancer. In this paper we evaluated 44 cases of atypical epithelium studied and treated in our institute. We found 3 cases of atypical epithelium associated with early gastric cancer. That is 2.66% of the total of all cases. We established the relationship of these lesions and following variables: age, size, localization, macroscopic shape and intestinal metaplasia. We found atypical epithelium in patients older than 50 years old, most of then smaller than 2 cm., localized in antrum and body gastric, and macroscopically were slight elevated lesions. Histologically all of them had intestinal metaplasia.

Adenocarcinoma↗