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Biomedical subjects

G Caputo

Publications and source records attributed to G Caputo.

At least 37 records · Page 2Linked to original sources
PubMed1998

Encapsulation of scleral buckling materials. A study of sixty specimens.

OBJECTIVE: The purpose of the study was to obtain information on the encapsulation of two nonabsorbable biomaterials (silicone and hydrogel) used as explants in scleral buckling in retinal detachment surgery. DESIGN: The study design was a histopathologic study on a cohort of capsule fractions and complete eyes. PARTICIPANTS: Fifty-nine patients participated in this study, in which 60 specimens, including 37 hydrogel and 21 silicone capsule specimens as well as 2 whole eyes, were gathered. There were no control subjects. INTERVENTION: The capsule specimens were obtained from eyes operated on previously for scleral buckling for retinal detachment. The two whole eyes were enucleated. All specimens were studied with routine optic microscopy. MAIN OUTCOME MEASURES: Patient characteristics, type of scleral buckling, and number of operations performed were analyzed. Histologically, the capsular structure, its interface with the explant, and its different components also were studied. Remnants of the buckling material also were investigated. RESULTS: There were 45 male and 14 female patients, with a mean age of 49 years. Histologically, capsule specimens had a fibrous matrix with fibroblasts and few inflammatory cells. Eighteen (48.6%) of 37 hydrogel capsule specimens displayed hydrogel fragments surrounded by a foreign body giant cell granuloma in 16 cases. CONCLUSION: Nonabsorbable materials undergo encapsulation after implantation on the eye surface. Giant cell granuloma was observed in some hydrogel capsule specimens in relation to hydrogel fragmentation. The exact origin of this fragmentation remains unknown.

Adolescent↗
PubMed1997

Object grouping contingent upon background.

This study analyzes grouping between singletons (line elements popping out by orientation gradient) when they segregate from textures of uniformly oriented line elements. In the first experiment three adjacent singletons formed a texture bar; in the second experiment the distance between two singletons to be grouped was manipulated. The observer's task was to discriminate the orientation of the global pattern made by the singletons. The results and the explanations suggested are that: (i) an inner gradient within the texture bar (when the singletons are reciprocally orthogonal) operates only at short distances and enhances discrimination, indicating an initial stage of texture segregation based on local processing. (ii) Spatial interactions between parallel singletons are present at short distances and reduce discrimination. (iii) An interruption of background flow (directed along the orientation of background line elements) produced by the grouped pattern when orthogonal to it, enhances discrimination; this effect is present at both short and large distances between singletons, indicating a global process. (iv) Spatial interactions are present between parallel singletons even at large distances and independently of background orientation, suggesting that grouping generates a figural context within which features to be bound together interact. Moreover, flow interruption and figural context were absent in a detection task, thereby suggesting their specific involvement in grouping and figure binding. Overall, the results may indicate that grouping operates on already segmented line elements, across different orientations and over both short and long distances in between.

Analysis of Variance↗
PubMed1997

[Rigid endoscope with Gradient-index lenses. Preliminary studies].

PURPOSE: Endoscopes for use in ophthalmology can be manufactured in dimensions smaller than 0.89 mm. MATERIALS: Gradient-index lenses that give a higher resolution than fiber bundles can be miniaturized down to 0.35 mm. RESULTS: We used this new endoscope in 6 eyes of 6 patients during anterior segment surgery. Preliminary clinical experience has demonstrated the usefulness and practical application of this new instrument. CONCLUSION: The clear views the instrument provides of the ciliary sulcus and ciliary body behind the iris make it useful in secondary posterior chamber intraocular lens implantation, retroprosthetic membrane behind keratoprosthesis, Molteno valve, and in endolaser photocoagulation.

Aged↗
PubMed1996

The role of the background: texture segregation and figure-ground segmentation.

The effects of a texture surround composed of line elements on a stimulus within which a target line element segregates, were studied. Detection and discrimination of the target when it had the same orientation as the surround were impaired at short presentation time; on the other hand, no effect was present when they were reciprocally orthogonal. These results are interpreted as background completion in texture segregation; a texture made up of similar elements is represented as a continuous surface with contour and contrast of an embedded element inhibited. This interpretation is further confirmed with a simple line protruding from an annulus. Generally, the results are taken as evidence that local features are prevented from segmenting when they are parts of a global entity.

Discrimination, Psychological↗
PubMed1996

Robust, reliable biosensor for continuous monitoring of urea during dialysis.

We developed a new urea sensor for the on-line monitoring of hemodialysis adequacy. The biosensor consisted of an immobilized urease cartridge placed between magnetoinductive conductivity cells. The biosensor output was taken as the conductivity difference between these cells. The device was placed on the ultrafiltrate line of a paired filtration dialysis system. The amount of urease present in the cartridge was sufficient for the complete conversion to ammonium carbonate of urea up to 35 mmol/L. Agreement was good between the urea concentration by the biosensor method and an automated analyzer for seven patients: range 8.07-30.3 mmol/L (22.6-84.8 mg/dL blood urea nitrogen, BUN); intercept 0.20 +/- 0.1 mmol/L (0.55 +/- 0.4 mg/dL BUN); slope 1.01 +/- 0.01; r 0.997; S(y/x) 0.40 mmol/L (1.11 mg/dL BUN). The device proposed meets the requirements of accuracy, cost, ruggedness, and ease of use (no calibration required) for a biosensor to be used for continuous monitoring of hemodialysis.

Animals↗
PubMed1993

Early experience with dobutamine stress testing and cardiac cine-tomographic imaging in the elderly: antianginal effects of nifedipine-GITS.

OBJECTIVE: To determine the effects of nifedipine-GITS (GITS = gastrointestinal transport system) on angina and cardiovascular responses to stress-dobutamine infusion, we used ultrafast cine-computed tomography (CT) to assess regional wall motion, myocardial perfusion, and indices of ventricular filling and emptying. DESIGN: Randomized, double-blind placebo-controlled efficacy study after an open-label dose titration phase. SETTING: University of California, San Francisco. PATIENTS: Elderly patients (> 60 years; n = 9:8 male, 1 female) with coronary artery disease by history and diagnostic treadmill or coronary angiography. INTERVENTION: After a 3-week open-label dose-titration phase, eight subjects were randomized to receive either placebo or nifedipine-GITS at the highest tolerated dose for 2 weeks, followed by a crossover to the alternate therapy for 2 weeks. One declined because of singulus in the open-label period. MAIN OUTCOME MEASURES: Symptomatic angina relief (frequency and nitroglycerin consumption), dobutamine stress responses (time to ischemia during dobutamine infusions, cardiac output, cardiac ejection fraction, ventricular segmental wall motion, and perfusion as measured by ultrafast cine-CT), and reported adverse effects. RESULTS: When compared with placebo, nifedipine-GITS administration was associated with less frequent angina and nitroglycerin consumption (NS) and significantly decreased systolic blood pressure. Nifedipine-GITS administration also increased resting supine heart rates. Dobutamine infusions increased heart rate, cardiac output, cardiac ejection fraction, and stroke volume and induced angina symptoms. Neither double product at angina nor systolic indices of cardiac function in response to dobutamine differed between nifedipine-GITS and placebo, although heart rate responses were greater during nifedipine. A trend toward increased peak filling rates was seen during dobutamine stress in the nifedipine-administration period. In most subjects (6/8), perfusion and regional wall motion abnormalities were not visualized on regional wall motion abnormalities were not visualized on either rest or stress cine-CT studies. Edema without congestive heart failure occurred frequently during nifedipine-GITS administration. CONCLUSIONS: These data suggest that (1) dobutamine stress can be used to induce cardiac ischemia in elderly patients with coronary artery disease, (2) nifedipine-GITS provides symptomatic angina relief in elderly patients, (3) peripheral edema is frequent in elderly patients on nifedipine-GITS, and (4) ultrafast computed cine-tomography testing can be used to assess ventricular performance, but current methodology may not detect perfusion or wall motion abnormalities during angina.

Age Factors↗
PubMed1992

Measurement of blood flow and perfusion in the cardiovascular system.

Complete evaluation of cardiovascular disease by a single imaging technique requires measurement of bulk flow in blood vessels and estimation of relative or ideally absolute perfusion at the tissue level. Magnetic resonance (MR) measurement of blood flow in arteries and veins has been done using the velocity-encoded phase cine gradient echo technique. This technique has been applied with cine MR to measure normal and pathologically high velocities. Measurement of relative perfusion in the myocardium has used the intravenous injection of T1 relaxation enhancing and magnetic susceptibility MR contrast media with rapid image acquisition using echoplanar imaging. MR images (MRIs) acquired during steady-state distribution or during the first passage of these contrast media have depicted ischemic myocardial regions.

Animals↗
PubMed1992

Cellular and molecular regulation of odontogenesis.

Developing mammalian tooth is one of the most interesting model systems to study the mechanism of morphogenetic process especially to understand problems associated with spatial organization and symmetry. In the present article we recapitulate the morphologic aspects of odontogenesis and discuss the cellular and molecular regulatory factors involved in this process. The importance of cellular aspects such as epithelial-mesenchymal interactions and the cell kinetics are described. Role of growth factors such as Transferrin, Epidermal Growth Factor and its receptor and Transforming Growth Factor is analyzed. In addition the studies on transcription factors such as c-fos and Egr-1 and on homeobox genes are discussed to understand the molecular mechanism of odontogenesis.

Animals↗
PubMed1990

Interstudy reproducibility of dimensional and functional measurements between cine magnetic resonance studies in the morphologically abnormal left ventricle.

The validity of geometric formulas to derive mass and volumes in the morphologically abnormal left ventricle is problematic. Imaging techniques that are tomographic and therefore inherently three-dimensional should be more reliable and reproducible between studies in such ventricles. Determination of reproducibility between studies is essential to define the limits of an imaging technique for evaluating the response to therapy. Sequential cine magnetic resonance (MR) studies were performed on patients with dilated cardiomyopathy (n = 11) and left ventricular hypertrophy (n = 8) within a short interval in order to assess interstudy reproducibility. Left ventricular mass, volumes, ejection fraction, and end-systolic wall stress were determined by two independent observers. Between studies, left ventricular mass was highly reproducible for hypertrophied and dilated ventricles, with percent variability less than 6%. Ejection fraction and end-diastolic volume showed close reproducibility between studies, with percent variability less than 5% End-systolic volume varied by 4.3% and 4.5% in dilated cardiomyopathy and 8.4% and 7.2% in left ventricular hypertrophy for the two observers. End-systolic wall stress, which is derived from multiple measurements, varied the greatest, with percent variability of 17.2% and 15.7% in dilated cardiomyopathy and 14.8% and 13% in left ventricular hypertrophy, respectively. The results of this study demonstrate that mass, volume, and functional measurements are reproducible in morphologically abnormal ventricles.

Adult↗
PubMed1989

Comparison of external jugular and peripheral venous administration of sodium bicarbonate in puppies.

We compared the administration of sodium bicarbonate via a catheter inserted in the external jugular and extending to the junction with the subclavian vein (group 1) and a peripheral hindpaw vein (group 2) in puppies. During spontaneous cardiac activity, the increases in pH (0.12 +/- 0.04 in group 1 vs. 0.08 +/- 0.04 in group 2) and PCO2 (11 +/- 2.8 torr in group 1 vs. 6 +/- 3.2 torr in group 2) in blood from the right atrium 10 sec after the injection of bicarbonate differed significantly. However, the increases in pH (0.31 +/- 0.07 in group 1 vs. 0.30 +/- 0.15 in group 2) and PCO2 (86 +/- 33 torr in group 1 vs. 72 +/- 35 torr in group 2) in blood from the right atrium during closed chest CPR were similar in the two groups. We found that the sodium bicarbonate reached the central circulation more rapidly when administered in the external jugular vein as compared to a peripheral site, but this difference was small and did not reach the level of significance during CPR. Our findings do not provide evidence of any advantage to obtaining central venous access (a potentially complicated procedure) in children with cardiac arrest in regard to the delivery of medications to the heart.

Animals↗
PubMed1989

The vascularization of the Bursa cloacalis (of Fabricius) in the duck.

The morphological and structural features of the vascular component of the bursa of Fabricius in the duck are described. By means of an intravasal perfusion of suitably colored neoprene Latex or Microscopaque, or a perfusion of Indian ink, it was possible to follow visually the routes of arteries, veins and the microcirculation; this last represents a major characteristic of the bursal follicle in the duck. The microcirculation has its origins in several roots arising from the follicular arterioles, which in the region of the cortex constitute an open vascular layer. From these pre-capillary arterioles, adjacent to the limiting layer between cortex and medulla, a dense capillary network is formed. With the aid of an electron microscope the presence of a cortico-medullary barrier of an epithelio-reticular nature was revealed; close to it there are the terminal branches of the intrafollicular network. The barrier appears to be structurally more compact than that of the cortical capillaries of the mammalian thymus.

Animals↗
PubMed1989

[Hyperthrophic-hyperplastic gingival diseases. Etiopathogenic, clinical assessment and diagnostic guide].

The clinical and histological aspects of hypertrophic and hyperplastic gum diseases were examined in order to clarify the aetiopathogenesis of such conditions and facilitate their diagnosis. The latter is far from simple, given the variety of pathological pictures expressing a large number of conditions that present macroscopic similarities despite their different aetiopathogenesis.

Anticonvulsants↗
PubMed1987

Phase contrast microscopy of the urine sediment for the diagnosis of glomerular and nonglomerular bleeding-data in children and adults with normal creatinine clearance.

In a pediatric and in an adult group of patients with hematuria and normal creatinine clearance overnight urine examination was carried out on 2 nonconsecutive days by means of phase contrast microscopy by two independent observers working in two different institutions. In this way it was possible to distinguish between patients on the basis of dysmorphic (glomerular) and isomorphic (nonglomerular) red cells in urine and to correlate the findings with the final diagnosis. A clear-cut indication (more than 80% of isomorphic and/or dysmorphic red cells) was obtained in 163 patients (102 of pediatric age) and final diagnosis of hematuria correlated with red-cell microscopy findings in 96.4% of glomerular diseases and in all cases of nonglomerular origin. Mixed hematuria (50-75% of dysmorphic red cells) was found in 2 cases of renal tuberculosis, 2 cases of polycystic kidney disease and in 1 child with viral meningoencephalitis with a bladder stone. The data indicate that the method is safe and accurate but further experience must be gathered for the many etiologies of glomerular and nonglomerular diseases hitherto not studied.

Adolescent↗
PubMed1987

[Development of suture materials: from the beginning to our day].

The history of suture materials from the beginnings to the II World War is reported. In this period, catgut and silk were the most employed sutures. The appearance and successive development of synthetic materials revolutionized the field of surgical sutures. This evolution is still active, to the search of ideal suture line.

History, 17th Century↗
PubMed1986

Effect of dichloroacetate in the treatment of anoxic lactic acidosis in dogs.

Lactic acidosis is seen frequently after severe anoxia and circulatory failure. Because dichloroacetate (DCA) has been shown to be effective in the treatment of lactic acidosis, we studied its effect on lactate levels and pH in arterial and sagittal sinus blood specimens in a pediatric canine model of anoxic cardiac arrest followed by CPR. Lactate levels rose steadily in all puppies receiving DCA alone (group 1), DCA plus bicarbonate (group 2), bicarbonate alone (group 3), or neither drug (group 4). Arterial and sagittal-sinus lactate levels were in the range of 2 mmol/L during the baseline period, 6 mmol/L after anoxic arrest, and 10 mmol/L after 20 min of CPR. Bicarbonate, but not DCA, significantly raised arterial pH. Neither drug reversed the progression of acidosis in the sagittal sinus; mean pH ranged from 6.85 to 6.92 among the four groups after 20 min of CPR. We speculate that DCA did not decrease lactate levels or raise the pH in either the peripheral circulation or the CNS (sagittal sinus) because of poor perfusion achieved during closed-chest cardiac compression.

Acetates↗
PubMed1986

In vitro and in vivo activity of LY 146032, a new cyclic lipopeptide antibiotic.

The in vitro activity of LY 146032, a cyclic lipopeptide antibiotic belonging to the class of agents designated A21978C, was compared with those of vancomycin, cefpirome, cefotaxime, and clindamycin against selected gram-positive bacteria. The new drug inhibited all staphylococcal isolates, including methicillin-resistant strains, at concentrations of less than or equal to 1.0 microgram/ml. The activity of LY 146032 was comparable to that of vancomycin against most streptococci, but the latter demonstrated greater potency against Streptococcus faecium and penicillin-resistant strains of pneumococci and viridans group streptococci. LY 146032 was markedly less active than vancomycin against Listeria monocytogenes (MICs for 90% of strains tested, 16 and 1.0 microgram/ml, respectively). The activity of LY 146032 was enhanced as the concentration of calcium in the test medium was increased. MBCs were within eightfold of the MIC for each of 12 strains tested. In a rat model of enterococcal endocarditis, the administration of LY 146032 resulted in increased survival and a reduction in the bacterial titer within cardiac vegetations compared with untreated control animals.

Animals↗