PubMed Health⌕ Search

Biomedical subjects

G Díaz

Publications and source records attributed to G Díaz.

At least 19 recordsLinked to original sources
PubMed2006

Routine use of pleural fluid cultures. Are they indicated? Limited yield, minimal impact on treatment decisions.

In pleural infection, it has been recommended that Gram stain and cultures should be obtained on a routine basis. However, this recommendation has not been tested prospectively. We evaluated the yield of microbiological studies in 259 patients with parapneumonic pleural effusion. Microbiological studies were positive on the pleural fluid of 50 patients (19.3%). In 48 of the 50 patients with positive microbiological results (96%), the need for pleural drainage was correctly predicted by pleural fluid parameters. There were no differences in hospital stay (9.5+/-2.5 days versus 9.9+/-3.2 days, P=0.68) or in mortality (2 deaths in each group, P=0.58) between the group of patients in which antibiotic treatment was changed according to microbiological results and the group of patients in which it is not. In conclusion, this study demonstrates that, at least in our institution, routine microbial investigation of pleural fluid adds very little to the standard management of parapneumonic effusions.

Adult↗
PubMed2005

Mycorrhizal synthesis of Lactarius indigo (Schw.) Fr. with five Neotropical pine species.

This paper describes for the first time the ectomycorrhiza synthesized between two Guatemalan strains of Lactarius indigo (Schw.) Fr. and the Neotropical species Pinus ayacahuite var. ayacahuite Ehren, P. hartwegii Lindl., P. oocarpa Schiede ex Schltdl. var oocarpa, P. pseudostrobus Lindl. and P. rudis Endl. The synthesis was carried out in a controlled growth chamber using plastic containers with peat moss-vermiculite substrate and mycelial inoculum. Mycorrhiza were obtained 25 days after inoculation. A description of the morphology, appearance and structure of mantle and Hartig net is given for each combination. Mycorrhiza were saffron to cinnamon greenish with age, with a net of saffron laticifers visible through outer mantle; orange latex secreted when injured. Cystidia-like emanating hyphae were observed on the mantle surface of young mycorrhiza. Plectenchymatous mantle with abundant interhyphal gelatinous material.

Agaricales↗
PubMed2005

[Prognostic value of syncope in the presentation of pulmonary embolism].

OBJECTIVE: Although the prognostic value of syncope has not been specifically addressed, it has generally been considered an indicator of poor prognosis in pulmonary embolism. The objective of this study was to carry out a prospective evaluation of the risk of recurrence and/or death in patients with pulmonary embolism that presents with syncope. PATIENTS AND METHODS: A total of 168 patients had a confirmed diagnosis of pulmonary embolism. Twelve were lost to follow up and did not enter statistical analysis. The mean follow-up period was 5 months. RESULTS: The prevalence of syncope in the patients studied was 22%. Of the 34 patients who presented syncope, objectively confirmed recurrence occurred in 2 (5.9%). In the patients who did not present syncope, recurrence was confirmed in 8 (6.6%; P=.8). Death occurred in 2 patients (5.9%) from the group presenting syncope and 15 (12.3%) from the remaining patients in the series (P=.4). The relative risk of recurrence and/or death associated with presentation of syncope was 0.5 (95% confidence interval, 0.2-1.8). A similar risk was obtained following adjustment for the presence or absence of cancer or deep vein thrombosis. CONCLUSIONS: Patients with pulmonary embolism that presents with syncope do not have an increased risk of recurrence and/or death.

Aged↗
PubMed2003

Yield of bronchoscopy in the diagnosis of neoplasm metastatic to lung.

The yield of fiberoptic bronchoscopy (FB) in the diagnosis of pulmonary metastases has not been conveniently analyzed. With the advances in the surgery of pulmonary metastases, there is a need to evaluate the diagnostic yield and the usefulness of FB to exclude other diseases with similar radiological patterns. To determine the value of FB in the diagnosis of pulmonary metastases we have retrospectively analyzed our experience in 113 patients with proven pulmonary metastases. An endobronchial lesion was identified in 57/113 (50.4%). The most frequent tumors with endobronchial lesions were thyroid (100%), head-neck (67%) and breast carcinomas (59%). The highest diagnostic yield was obtained combining techniques of brushing, washing and biopsy (72.6%); in cases with endobronchial lesions (84.2%) and with certain histological types (head-neck 100%; breast 90.9% and colon 84.6%). The most frequent radiological findings were single or multiple nodules (77.9%). Atelectasis were associated with endobronchial lesions. In conclusion, bronchoscopy is a valuable diagnostic procedure in selected patients with metastatic lung disease.

Bronchoscopy↗
PubMed2003

Prognostic features of residual pleural thickening in parapneumonic pleural effusions.

The objective of the study was the identification of predictive factors for the development of residual pleural thickening (RPT) in patients with parapneumonic effusion. The design of the prospective study involved investigating patients with parapneumonic pleural effusions diagnosed between March 1991 and December 2000 in the respiratory department of Hospital Ramón y Cajal (Madrid, Spain) which is a 1,500 tertiary-care hospital. The clinical and radiological characteristics and measurements of microbiological and biochemical variables in the pleural fluid taken from the patients were studied. RPT was defined in a posteroanterior chest radiograph as pleural thickening of > or = 10 mm measured at the lateral chest wall at the level of an imaginary line, tangent to the diaphragmatic dome. A total of 48 of the 348 patients studied (13.79%) were found to have RPT. Among the factors studied, only presence of pus in the pleural space, Fine classes IV and V, temperature > or = 38 degrees C and delayed resolution of pleural effusions after diagnosis (> 15 days) were independently associated with the risk of RPT. This study showed that significant residual pleural thickening was not a common complication of parapneumonic pleural effusions. There are certain risk factors for the development of residual pleural thickening. However, this complication was not associated with long-term functional repercussions in the series of patients involved in this study.

Adult↗
PubMed2002

Evidence for discoordinate regulation of the HLA-DPB1 gene.

Characterization of cell lines derived from patients with type II bare lymphocyte syndrome, a pathological state in which the constitutive and inducible expression of HLA class II antigens is lacking, has permitted the identification of several trans-acting factors involved in the coordinated regulation of HLA class II genes. Although an increasing body of evidence has pointed to the existence of a discoordinate regulation of HLA class II loci, the mechanisms underlying such regulation are essentially unknown. In the present study, 45.EM2, a mutant lymphoblastoid cell line with a new pattern of HLA discoordinate expression is characterized. 45.EM2 expresses HLA-DR and -DQ but fails to express HLA-DP. The absence of HLA-DP expression in 45.EM2 is the result of a transcriptional defect, leading to a lack of DPB1 mRNA. By contrast, DPA1 transcription in this LCL is not impaired. The characteristics of 45.EM2 described here suggest the existence of a specific trans-acting factor involved in the control of DPB1 gene expression.

Cell Line, Transformed↗
PubMed2001

Medical treatment for neurocysticercosis characterized by giant subarachnoid cysts.

BACKGROUND: Infection with the larval form of the pork tapeworm, Taenia solium, can lead to the development of cysts in the brain. Surgical removal of cysts has been the accepted treatment for neurocysticercosis characterized by giant cysts when there is associated intracranial hypertension. METHODS: We describe 33 patients whom we treated medically for malignant forms of neurocysticercosis. All patients had evidence of intracranial hypertension and subarachnoid cysts at least 50 mm in diameter. All patients received 15 mg of albendazole per kilogram of body weight per day for four weeks. Ten patients were also treated with 100 mg of praziquantel per kilogram per day for four weeks. Seventeen patients received a second course of albendazole, three received a third course, and one received a fourth course. During the first cycle of treatment, all patients also received dexamethasone. Five patients had previously undergone neurosurgery for giant cysts. RESULTS: After a median of 59 months of follow-up (range, 7 to 102), the condition of all 33 patients had improved, and the cysts had disappeared or become calcified. Of the 22 patients with a history of seizures, only 11 continued to receive antiseizure medications. The median quality-of-life score on the Karnofsky scale improved from 40 to 100. Fifteen patients received a ventriculoperitoneal shunt because of hydrocephalus. Four patients had persistent sequelae (bilateral partial optic atrophy, stroke, or diplopia) of the cysts. CONCLUSIONS: Intensive medical treatment can be effective in patients with neurocysticercosis characterized by giant cysts. Neurosurgery may be required only when there is an imminent risk of death.

Adolescent↗
PubMed2001

Epidemiology of acute carbon monoxide poisoning in a Spanish region.

BACKGROUND: In Spain, as in most of the world, the incidence of acute carbon monoxide poisoning is probably underestimated. METHODS: During an eighteen-month period we studied, by means of a standardized data collection form, all the cases of acute carbon monoxide poisoning that were diagnosed in 2 university hospitals. RESULTS: During the study, 154 patients were diagnosed with carbon monoxide poisoning. The mean age was 32.2+/-15.5 years. The two principal exposure sites were the kitchen (43%) and bathroom (23%). The majority of the cases related to malfunction of the water heater (30%) and of the central heating (23%) and 68% occurred in the home. Improper combustion of butane (31%), propane (13%), and natural gas (12%) were most frequent. The most prevalent clinical manifestations were headache (94%), dizziness (56%), nausea (45%), loss of consciousness (38%), and weakness (34%). Five patients died. In 14.4%, symptoms suggested delayed neurological syndrome. The largest number of cases of poisoning occurred during the months of December and January. CONCLUSIONS: Compared with previous Spanish series or with the antecedent year, acute carbon monoxide poisoning has a high prevalence in our region. Two factors appear to be essential to the accurate diagnosis of acute carbon monoxide poisoning: 1) the ability of emergency room physicians to recognize the clinical symptoms of carbon monoxide poisoning and 2) access to a carbon monoxide-oximeter.

Adolescent↗
PubMed2000

Immunolabeling reveals cellular localization of the N-methyl-D-aspartate receptor subunit NR2B in neurosecretory cells but not astrocytes of the rat magnocellular nuclei.

Previous studies suggest that activation of N-methyl-D-aspartate (NMDA) receptors facilitates phasic firing and spike clustering displayed by magnocellular neuroendocrine cells (MNCs) of the supraoptic (SON) and paraventricular nucleus of the hypothalamus (PVN). Osmotic stimulation produces similar activity patterns which, in turn, can lead to enhanced release of vasopressin and oxytocin from MNCs. Our laboratory has shown that dehydration regulates the expression of the NMDA receptor subunits, NR1 and NR2B, in the SON and PVN, suggesting their involvement in osmoregulation. In the present study, we examined the cellular localization of NR2B, one of the glutamate-binding subunits of the NMDA receptor, with an NR2B-specific antibody. Using double-label immunohistochemistry and three different detection methods with metallic, peroxidase, and fluorescence markers, it was found that both vasopressin and oxytocin-producing MNC populations synthesize NR2B. The incidence of NR2B colocalization with vasopressin-neurophysin in the SON and lateral magnocellular PVN (PVL) was 0.95 and 0.91, respectively. For oxytocin-neurophysin, the corresponding values were 0.97 and 0.95, respectively. Furthermore, the extent of colocalization in MNCs of the SON, PVL, retrochiasmatic SON, and accessory neurosecretory nuclei was similar. Astrocytes associated with the SON, and identified with antibodies targeting glial fibrillary acidic protein (GFAP) or vimentin, were not colabeled with NR2B. Our results demonstrate that NR2B protein is expressed by almost all MNCs and that it is equally prevalent in vasopressinergic and oxytocinergic populations of various magnocellular neuroendocrine nuclei supporting a role of NMDA receptors in MNC-mediated neurosecretory processes. Although NR2B may form part of functional NMDA receptors on MNCs, it is probably not present on astrocytes associated with nearby MNCs.

Animals↗
PubMed2000

Thermal constant estimation in tropical horse tick, Anocentor nitens (Acari:Ixodidae).

Experience has demonstrated that the exclusive use of acaricides as a control method against cattle ticks causes several problems, and is not totally effective. Other methods need to be added in order to achieve better and more profitable control of these parasites. Groups of 12 to 15 engorged ticks, bred on bovines, were individually incubated at six temperatures (T = 24, 26, 28, 30, 32, and 34 degrees C) and four relatives humidities (RH = 100, 80, 75.5, and 70%), creating 24 variants. The onset of oviposition and eclosion (emergence of larvae from eggs) was observed in all ticks, and preeclosion times (PET) were determined. A linear regression equation for the velocity of development with temperature as a function of the inverse of PET was calculated for each RH value. For each RH the minimum thermal threshold (MTT) was obtained by extrapolation and the effective temperature summation (ETS) calculated from the equation (incubation temperature--MTT) x PET. The four MTT values obtained were not significantly different; the mean value of MTT was 15.25 degrees C. The thermal constants did not prove to be not statistically different over the range of RH values employed in the experiments, the mean being 354.04 degrees C-day.

Animals↗
PubMed2000

Larval survival of Anocentor nitens under simulated natural conditions.

Basic knowledge about the survival of free living stages of ticks is of great importance as a practical tool to improve control methods. For Anocentor nitens there is little information on this subject. Eighty-four engorged females were incubated at 30 degrees C and 100% relative humidity. After 17 days, groups of 5,500 eggs each were collected and isolated in vials. Age zero was defined as 10 days after eclosion had begun. At this time vials with larvae were attached to 40 Sorghum halepense plants sowed in clay pots, under outdoor conditions, and separated from one another by 30 cm in order to prevent the larvae from mixing. Four hours later vials were retired and the larvae remaining in the vials were counted. The next day four plants were sampled and this survival considered as 100%. Each week for eight weeks the same sampling procedure was performed. The remaining four plants were used to determine the maximum larval survival (MLS). Four repetitions of the procedure were performed, two in March 1989 and two in September 1989.

Animals↗
PubMed2000

Artificial feeding in Boophilus microplus (Acari:Ixodidae) through micropipettes.

Newly molted Boophilus microplus females obtained in a laboratory at 30 degrees C and environmental relative humidity (RH) were employed. An original device was used to hold ticks during feeding. Three groups of 15 ticks each were created: unfed, fed with heparinized blood, and fed with defibrinated blood. Ticks were weighed before and after feeding. Females were restricted by group in three isolators attached on the skin of a bovine. Ten sexually competent males were added to each isolator. Time of coupling, tick mortality, time of detachment, and weight of engorged ticks were determined. Engorged females were incubated at 30 degrees C and 100% RH. Periods of nonparasitic phase, laying efficiency, and fertility of eggs were noted. There were no statistical differences between the three groups. This means that feeding with micropipettes does not affect the non-parasitic phase of B. microplus, the differences between heparinized and defibrinated blood are not significant.

Animals↗
PubMed2000

[Seroprevalence of infection by St. Louis encephalitis virus in the Province of Formosa].

The aim of this work was to determine the prevalence of antibodies against St. Louis encephalitis virus (SLE) in human sera provided by the Laboratory of Epidemiological Surveillance from Formosa District (Province of Formosa, Argentina) in 1995 and 1997. The tests used for this study were hemagglutination inhibition (HI) and neutralization (NT). The screening performed by NT test showed prevalences of 21% (60/284) and 32% (50/157) of antibodies in samples obtained in 1995 and 1997 respectively. In 1995, 14% of tested sera showed low titer of neutralizing antibodies (NT) (1/20 and 1/40) whereas in 1997, 19% of the sera presented titers of NT antibodies equal or greater than 1/80. It was observed that sera with low titers of NT antibodies (1/20-1/40) resulted negative in HI in the simultaneous titration of antibodies by NT and HI whereas other sera presented high titers for both tests. This relation between the low and the high titers of antibodies indicates the presence of past and recent infections and the continuous circulation of this virus. Moreover, the prevalence of NT antibodies in the surveyed population increased significantly in 2 years (p < 0.0075) confirming the endemicity of this agent in this area and showing the need to perform studies of non-confirmed viral etiology febrile diseases to determine its importance in human pathogenicity.

Adolescent↗
PubMed1999

Sources of Vibrio mimicus contamination of turtle eggs.

Vibrio mimicus contamination of sand increased significantly during the arrival of the olive ridley sea turtles (Lepidochelys olivacea) at Ostional anidation beach, Costa Rica. Statistical analysis supports that eggs are contaminated with V. mimicus by contact with the sand nest. V. mimicus was isolated from eggs of all nests tested, and ctxA+ strains were found in 31% of the nests, all of which were near the estuary.

Animals↗
PubMed1999

Modification of pleural fluid pH by local anesthesia.

BACKGROUND: It is a common practice to anesthetize patients before performing a thoracentesis. We postulated that this technique may cause a clinically significant difference in the pH of the pleural fluid. METHODS: We compared two methods of determining pleural fluid pH. Fifty patients undergoing diagnostic or therapeutic thoracentesis were enrolled. Two 4-mL aliquots of pleural fluid were anaerobically collected into blood gas syringes containing heparin, one before (group A) and the other after (group B) anesthetizing the patient with 5 mL of 2% mepivacaine. pH was then determined on both samples using an arterial blood gas machine. Agreement analysis was performed overall and in subcategories of pH used to define complicated (<7.1), borderline (7.1 to 7.3), or uncomplicated (>7.3) parapneumonic effusions. We analyzed these same data stratified by the volume of pleural fluid in relationship to the size of the hemithorax (<15% and >15%). RESULTS: There was a statistical difference between the mean pH in both groups (group A, 7.32; group B, 7.28; p<0.0001). There was a significant correlation between the two measures (r = 0.97; p<0.0001). Using the pH subcategories, there was 45% discordance in classification for patients with parapneumonic effusions. The pH values obtained in group B wrongly predicted whether the patient required a chest tube in two of four cases (50%). In patients with effusions that occupied <15% of the affected hemithorax, there was an 80% discordance in classification for patients with parapneumonic effusions, and the pH values obtained in group B wrongly predicted whether the patient required a chest tube in two of two cases (100%). CONCLUSIONS: Local anesthesia is typically used before thoracentesis is performed. However, in cases of suspected parapneumonic effusions that occupy <15% of the affected hemithorax, pH results may be significantly altered by use of local mepivacaine anesthesia.

Adult↗