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Biomedical subjects

A Garcia

Publications and source records attributed to A Garcia.

At least 235 records · Page 13Linked to original sources
PubMed1993

Evaluation of myocardial perfusion defects by means of "bull's eye" images.

The purpose of this study was to evaluate the usefulness of so-called "bull's eye" imaging as a simplified display of tomographic slices in the detection of coronary artery disease (CAD). A total of 64 patients were studied at stress and at rest, by single photon emission computed tomography (SPECT), either with thallium-201 (201Tl) or with technetium-99m methoxy-isobutyl-isonitril (Tc-MIBI). The myocardial perfusion defects detected by bull's eye image alone and in combination with visual analysis of tomographic images were evaluated in all cases, taking coronary arteriographic results as a gold standard. The overall sensitivity and specificity for detection of CAD were as follows: bull's eye imaging, 100% and 70.8%; tomographic imaging (SPECT), 90% and 91.6%. The results of bull's eye imaging and SPECT interpreted together were 96.6% and 83.3%. The regional sensitivity and specificity of bull's eye for individual coronary arteries were: right coronary artery (RCA), 100% and 73.7%; left anterior descending (LAD), 100% and 87.2%; left circumflex (LCx), 100% and 97.3%. For SPECT they were: RCA, 93.7% and 89.5%; LAD, 86.6% and 92.3%; LCx, 73.3% and 97.4%. For bull's eye with SPECT they were: RCA, 94.4% and 86.1%; LAD, 87.5% and 92.1%; LCx, 82.3% and 97.2%. We conclude that the bull's eye image display allows an easier and more objective assessment of myocardial perfusion defects and shows higher sensitivity. However, it has a relatively low specificity which can cause an overestimation of perfusion defects. Thus, visual analysis of bull's eye imaging is a useful diagnostic tool but must be evaluated in conjunction with tomographic imaging.

Adult↗
PubMed1993

Detection of ascorbic acid in the eye of the early chicken embryo by silver staining.

Ascorbate is found in high concentrations in the aqueous, lens and retina of a variety of animal species. Several functions have been proposed for this, including a vital role in aqueous secretion. We investigated the possible presence of ascorbate in the early embryonic chicken eye as a marker for the differentiation of the ciliary epithelium. Embryonic chicken eyes were processed for histochemical demonstration of ascorbate by silver staining. A strongly positive reaction was found in the interstitial matrix between the lens rudiment and the optic vesicle of the 2-day chicken embryo. By 3 days, with lens and optic cup separating from each other, the silver grains were concentrated in the vitreous cavity, primarily in a band-like configuration between the lens equator and the rim of the optic cup, which is the presumptive ciliary epithelium. A weaker reaction was seen in the lens vesicle and primitive neural retina. During the second and third day of incubation the optic vesicle is just beginning to expand. The appearance of ascorbic acid in the newly formed vitreous cavity at this time may indicate its importance in the biosynthesis of the matrix that is filling the expanding optic vesicle.

Animals↗
PubMed1993

The periodontal treatment needs of Malagan adults.

The Periodontal treatment needs of 908 subjects aged 18-64 years in Málaga, Spain were assessed using the Community Periodontal Index of Treatment Needs (CPITN). The percentage of subjects scored periodontally healthy decreased with age, 18-64 yrs., from 22% to 3%. Conversely periodontal pocketing increased with age from 2% to 55%. Calculus was a very prevalent score at all ages, about 60% overall. No significant differences in periodontal treatment needs were identified among the three defined socio-economic groups, but the health professional group had fewer periodontal pockets than the other two groups. Treatment needs increased significantly with age in all groups. For the WHO standard age group 35-44 yrs 8% of 180 were scored healthy, 66% were scored for calculus or bleeding only, 23% with shallow pockets and 3% with deep pockets. An average of 2 out of 6 sextants were found health and 2.6 (43%) had calculus or other retentive factors.

Adolescent↗
PubMed1993

Effect of stress, adrenalectomy and changes in glutathione metabolism on rat kidney metallothionein content: comparison with liver metallothionein.

Eighteen hours of immobilization stress, accompanied by food and water deprivation, increased liver metallothionein (MT) but decreased kidney MT levels. Food and water deprivation alone had a significant effect only on liver MT levels. In contrast, stress and food and water deprivation increased both liver and kidney lipid peroxidation levels, indicating that the relationship between MT and lipid peroxidation levels (an index of free radical production) is unclear. Adrenalectomy increased both liver and kidney MT levels in basal conditions, whereas the administration of corticosterone in the drinking water completely reversed the effect of adrenalectomy, indicating an inhibitory role of glucocorticoids on MT regulation in both tissues. Changes in glutathione (GSH) metabolism produced significant effects on kidney MT levels. Thus, the administration of buthionine sulfoximine, an inhibitor of GSH synthesis, decreased kidney GSH and increased kidney MT content, suggesting that increased cysteine pools because of decreased GSH synthesis might increase kidney MT levels through an undetermined mechanism as it appears to be the case in the liver. However, attempts to increase kidney MT levels by the administration of cysteine or GSH were unsuccessful, in contrast to what is known for the liver. The present results suggest that there are similarities but also substantial differences between liver and kidney MT regulation in these experimental conditions.

Adrenal Glands↗
PubMed1993

Dielectric spectroscopy of mammalian cells. 1. Evaluation of the biomass of HeLa- and CHO cells in suspension by low-frequency dielectric spectroscopy.

The capacitance of suspensions of CHO and HeLa cells (0.5-3 x 10(6) cells/ml) has been measured between 0.2 and 10 MHz. As frequencies decrease, there is a continuous increase in capacitance of both the cell suspension and the spent growth medium free of cells, a phenomenon which is partially attributed to an increased polarisation of the electrodes. At a given frequency, subtraction of the capacitance of the spent medium from that of the cell suspension allows one to determine the capacitance of the cells only. The intensity of this signal varies linearly with the biomass and cell size. At low frequencies such as those used in this study (0.25 MHz), where sensitivity is the highest, concentrations as low as 0.5 x 10(6) cells/ml can be accurately measured. Suggestions are made how to make these measures on-line, non-invasive and in real time.

Animals↗
PubMed1993

Dielectric spectroscopy of mammalian cells. 2. Simultaneous in situ evaluation by aperture impedance pulse spectroscopy and low frequency dielectric spectroscopy of the biomass of HTC cells on Cytodex 3.

Low-frequency dielectric spectroscopy has been used in situ, i.e. while the cells are still attached to their microsupport, to monitor the changes of biomass accompanying the growth of anchorage-dependent cells. This method, when compared to Aperture Impedance Pulse Spectroscopy (also called electronic sizing), is characterized by a somewhat lower degree of resolution. Suggestions are made on how to determine the capacitance of the spent growth medium alone, still keeping the probe inserted in the bioreactor. This will make dielectric spectroscopy the first truly in situ, on-line, in real time, non-invasive measure of the biomass.

Cell Division↗
PubMed1993

Synthesis of nitric oxide in CNS glial cells.

Attention has focused on particular neurons as the source of nitric oxide (NO) within the parenchyma of the CNS. In contrast, glial cells have been viewed mainly as potential reservoirs of L-arginine, the substrate for nitric oxide synthase (NOS), and as likely targets for neuronally derived NO because of their proximity and their expression of soluble guanylyl cyclase (sGC). However, it is becoming evident that astrocytes display both constitutive and inducible NOS activity under various conditions, and that activated microglia express an inducible NOS. The NO-producing capacity of oligodendrocytes is not yet known. Glial-derived NO has significant implications for CNS pathophysiology, given the anatomical location and abundance of these cells, and the wide variety of potential interactions that NO can have with cellular biochemistry. Our intention here is to evaluate the evidence for NO production from non-neuronal CNS sources and thus prompt discussion about potential 'nitrinergic' roles for glial cells.

Amino Acid Oxidoreductases↗
PubMed1993

High-affinity and intermediate-affinity forms of the human interleukin 2 receptor, expressed in an interleukin 9-dependent murine T cell line, deliver proliferative signals via differences in their transduction pathways.

Although several reports have claimed that the p70 IL-2R per se transduces a growth signal in lymphoid and non-lymphoid systems, there is no convincing evidence for this in lymphoid T cell lines. In order to investigate the mechanism of IL-2R-dependent signal transduction pathways via the p70 IL-2R in lymphoid T cells, we have established two IL-9-dependent murine (TS1) cell lines stably expressing the human p70 IL-2R subunit or the human p55-p70 IL-2R complex. Whereas the parental T cell line, TS1, proliferated in response to IL-9 or IL-4 but not IL-2, cell lines stably expressing human p70 IL-2R or p55-p70 IL-2R complex proliferated in response to IL-2. This implies that the murine T cell, TS1, contains all the intracellular components necessary for directing IL-2 signalling. In human p55-p70 IL-2R-transfected cells, the expression of a functional murine p55 IL-2R seemed to be induced and regulated by IL-2. In human p70 IL-2R-transfected cells, in the presence of IL-2 an interaction requiring only intermediate-affinity was sufficient for transduction of a proliferative signal. In addition human p70 IL-2R per se, is biologically functional via a transduction pathway not requiring induction of murine p55 IL-2R and consecutive high-affinity complex reconstitution. Thus, although both transfected cell lines can transduce a proliferative signal in the presence of IL-2, a difference in their transduction pathway is probably involved for the induction of p55 IL-2R.

Animals↗
PubMed1993

Prognostic value of exercise radionuclide angiography in low risk acute myocardial infarction survivors.

Patients with an uneventful course during hospital stay, which represent from 30 to 50% of all myocardial infarction survivors, still have an incidence of new coronary events up to 7% during the first year of follow-up. To assess the value of radionuclide angiography in predicting new coronary events in this low risk population, 93 patients without evidence of left ventricular failure or recurrent postinfarction angina underwent rest and exercise radionuclide angiography and treadmill exercise testing before hospital discharge. During follow-up (16 +/- 5 months, range 12 to 32) 14 patients developed new coronary events: two patients died, four had a new myocardial infarction and the remaining eight had unstable angina. There were no differences regarding clinical variables, the results of the exercise test and the resting ejection fraction, between patients with or without new coronary events; however, patients without events during follow-up exercised longer during both exercise treadmill test and exercise radionuclide angiography. Resting end-diastolic and end-systolic volume indexes were higher in patients presenting coronary events (122 +/- 50 vs 92 +/- 32 ml.m-2, P < 0.05, 69 +/- 47 vs 47 +/- 26 ml.m-2, P < 0.05). These patients also had a higher incidence of wall motion abnormalities in more than one area (64 vs 28%, P < 0.02). During exercise, ejection fraction increased significantly in patients with an uneventful outcome (49 +/- 13 to 56 +/- 14%, P < 0.01), while it did not change in their counterparts (46 +/- 14 to 45 +/- 14%, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Activity of imipenem, third-generation cephalosporins, aztreonam and ciprofloxacin against multi-resistant gram-negative bacilli isolated from Chilean hospitals.

The activity of imipenem against nosocomial strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp. and methicillin-resistant Staphylococcus aureus resistant to some third-generation cephalosporins, aztreonam, or ciprofloxacin was assessed. These strains represent the most prevalent multi-resistant nosocomial microorganisms in Chile since they were isolated from clinical specimens in 11 Chilean hospitals. A high proportion of the strains were resistant to several beta-lactams, yet all strains of K. pneumoniae and Acinetobacter spp. were susceptible to imipenem; resistance was exhibited by only one strain of P. aeruginosa and 16 strains of S. aureus. Synergy between cefotaxime and clavulanic acid was found in almost all strains of K. pneumoniae, suggesting the presence of plasmid-coded beta-lactamases, probably with extended-spectrum activity. Killing A. baumannii by imipenem was rapid, but slower for P. aeruginosa. Killing of K. pneumoniae was also somewhat slower despite the lower MIC of imipenem for this strain. Bactericidal activity was even slower against one strain of methicillin-resistant S. aureus. These results suggest that imipenem would be an adequate alternative to other broad-spectrum agents in the treatment of infections due to nosocomial multi-resistant Gram-negative bacilli.

Anti-Bacterial Agents↗
PubMed1993

Rapidly destructive hip disease: clinical and imaging abnormalities.

The clinical and radiographic records of 23 patients (15 women, eight men) with rapidly destructive hip disease (RDHD) were retrospectively reviewed. Criteria for RDHD included a history of hip pain of 1-6 months duration and the radiographic appearance of a rapidly progressive atrophic form of bone destruction involving both the femoral head and the acetabulum. Radiographs of the remainder of the appendicular skeleton were assessed in 14 patients. The mean patient age was 72 years. The average time from clinical presentation to the appearance of severe hip destruction was 14 months. Five patients demonstrated similar atrophic bone destruction around other articulations. No patients had clinical or laboratory evidence of sepsis or neurologic disease. Although previous reports have suggested that RDHD is degenerative in nature, similar involvement of other articulations suggests that it may represent a focal finding of a more generalized process.

Aged↗
PubMed1993

Evaluation of the "Auto-Stat 6010" automatic osmometer and its comparison with the "digimatic-advanced 3DII" manual osmometer.

The results are presented of a comparative study between two osmometers, a manual one, Digimatic-Advanced 3DII (Advanced Instruments, Medical Europa, Barcelona), and an automatic one, Auto-Stat 6010 (Kyoto, Daiichi, Kagaku, Menarini, Firenze). Both osmometers have the same operation principle, but they employ different systems for determination of the freezing point depression. Both instruments showed good precision (CV < 1%), accuracy, and a wide range of linearity. In the assay of 133 sera and 101 24-h urines, the methods showed a good correlation (r = 0.945 and r = 0.999) and the Anova test showed no statistical difference between the means (p > 0.05). The carry over effect in the Auto-Stat was statistically significant (p < 0.001) but within the range of imprecision of the osmometers. Variation due to evaporation is lower than 0.8%. In conclusion, we are sure that both osmometers are useful in the laboratory, although the Auto-Stat 6010 osmometer has the advantage over the Digimatic-Advanced 3DII of automatic sample processing.

Calibration↗
PubMed1993

Occupational noise as a cardiovascular risk factor.

The results from routine medical screening of 806 workers in a very wide range of different occupational activities were analysed in order to assess the relationship between blood pressure and occupational exposure to noise. Blood pressure was measured for each worker by conventional methods. Noise exposure was estimated according to the main company activity and each worker's specific job, computing three categories of noise exposure: low, medium and high. Preliminary analysis of the data did not reveal any relationship between noise exposure and blood pressure. Nevertheless, when comparing two groups of workers with noise induced hearing loss (NIHL) at 4000 Hz higher and lower than 65 dB, the group with the highest NIHL also shows the highest mean blood pressure value and the highest proportion of hypertensive workers (however, these results are statistically not significant). The limitations and problems posed by the methods used to assess the effects of occupational noise exposure as a cardiovascular risk factor are discussed.

Adult↗
PubMed1993

Biological monitoring of workers at a recently opened hazardous waste disposal site.

A health assessment was performed in a recently opened landfill for toxic waste. The site has received 14,000 tons of hazardous waste, confined in drums or deposited as bulk material, which were left outdoors for seven months. The analysis in some samples showed that the waste is rich in heavy metals, however we did not find high levels of contaminates in air or surface soil in different areas on-site. When compared to a control group, high-risk workers show higher levels of arsenic in urine and hair, and non-specific symptoms (irritability and insomnia). But among groups, we did not find statistical differences in urinary mercury, blood lead, phenol in urine, cadmium in hair or blood, sister chromatid exchange values, lymphocytes proliferation kinetics, liver function tests, and other non-specific symptoms. We considered this project as a background study for human exposure to hazardous waste, providing useful results for the future evaluation of chronic effects in the same population.

Adult↗
PubMed1992

Weekly first-line chemotherapy of metastatic breast cancer with cyclophosphamide and epirubicin.

Forty-six patients with metastatic breast cancer who had not received previous chemotherapy for advanced disease entered a phase II trial of weekly chemotherapy with cyclophosphamide (250 mg/m2) + epirubicin (25 mg/m2) for 16 weeks. The overall response rate was 61% (95% confidence limits, 47-75%), with 10 complete and 17 partial responses. Toxicity was mild and confined to nausea and vomiting and asymptomatic neutropenia (except in 2 cases). Sixty-three per cent of patients had no side effects. Weekly cyclophosphamide + epirubicin is an active and nontoxic regimen for patients with metastatic breast cancer who have had no prior anthracycline-containing adjuvant chemotherapy.

Adult↗