Biomedical subjects
Publications and source records attributed to R Garcia.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The aim of three-dimensional conformal therapy (3DCRT) is to treat the Planning Target Volume (PTV) to the prescribed dose while reducing doses to normal tissues and critical structures, in order to increase local control and reduce toxicity. The evaluation tools used for optimizing treatment techniques are three-dimensional visualization of dose distributions, dose-volume histograms, tumor control probabilities (TCP) and normal tissue complication probabilities (NTCP). These tools, however, do not fully quantify the conformity of dose distributions to the PTV. Specific tools were introduced to measure this conformity for a given dose level. We have extended those definitions to different dose levels, using a conformity index (CI). CI is based on the relative volumes of PTV and outside the PTV receiving more than a given dose. This parameter has been evaluated by a clinical study including 82 patients treated for lung cancer and 82 patients treated for prostate cancer. The CI was low for lung dosimetric studies (0.35 at the prescribed dose 66 Gy) due to build-up around the GTV and to spinal cord sparing. For prostate dosimetric studies, the CI was higher (0.57 at the prescribed dose 70 Gy). The CI has been used to compare treatment plans for lung 3DCRT (2 vs 3 beams) and prostate 3DCRT (4 vs 7 beams). The variation of CI with dose can be used to optimize dose prescription.
Accuracy of conformal treatment planning for prostatic radiotherapy is based on the contours of target volumes (prostate +/- seminal vesicles) and normal tissues (rectum and bladder), drawn on CT (computed tomography) images by radiation oncologists. The interpretation of a given CT image can be different from one radiation oncologist to another, and may change in time with the state of filling of the bladder and of the rectum during the treatment. In order to quantify these variations, 12 patients treated with conformal radiotherapy for prostate carcinoma (pelvis 40 Gy/20 sessions + prostate 30 Gy/15 sessions) had two series of CT at one month intervals. Contouring of prostate, rectum and bladder were performed independently on each CT by two radiation oncologists. The first CT scan (planning CT) and the first series of contours (planning contours) were used for treatment planning. The contours of the second scan were compared to the planning contours after image fusion based on manual superimposition of bony anatomy of the two sets of CT images. Coherence ratio were defined to measure discrepancies in prostate volumes between radiation oncologists (RCE) and between scans (RCT). The mean RCE was 38 +/- 7% (1 standard deviation). Those discrepancies were primarily located at the prostate apex and at the interface between bladder and prostate and between rectum and prostate. The mean RCT was 42 +/- 8% (1 sigma). Those discrepancies were due to the prostate motion related to the state of filling of the rectum and bladder. For bladder and rectal walls, less important differences were observed between the two radiation oncologists for the same CT (4.5% for rectal volume receiving 65 Gy or more, 3% for bladder volume receiving 65 Gy or more). However, important differences in bladder and rectal volumes receiving 65 Gy or more (16% and 7% respectively) were noted for the same patient from a CT to another due to the variation in bladder or rectal filling. New techniques for planning CT acquisition are needed to decrease the discrepancies due to contouring. The treatment must, as far as possible, be delivered with an empty bladder and rectum in order to ensure a good reproduction of the initially planned treatment.
Explore the source record for details and available documents.
BACKGROUND AND OBJECTIVES: DNA amplification fingerprinting is used in most epidemiologic studies as a substitute for conventional typing methods. DNA amplification fingerprinting and conventional typing methods were compared in this epidemiologic study of Neisseria gonorrhoeae. GOAL OF THIS STUDY: To differentiate 70 Neisseria gonorrhoeae isolates from untreated patients with urogenital gonococcal infection. STUDY DESIGN: Gonococcal strains were characterized by auxotyping, serotyping, plasmid profile, antibiotic sensitivity, and DNA amplification fingerprinting. The method of unweighted pair-group average linkage was used for cluster analysis. Discriminatory power was calculated applying Simpson's index. RESULTS: Amplification of Neisseria gonorrhoeae DNA with primers OPA-03 and OPA-13 produced well-resolved patterns of 15 and 22 DNA fragments, respectively, with a discriminatory power (0.978 with OPA-13 and 0.967 with OPA-03) comparable to that obtained with auxotyping/serotyping combination (D:0.968) or with auxotype/serotype/plasmid profile combination (D:0.983). Correlation between DNA amplification fingerprinting pattern and auxotype/serotype class was not always uniform. Some strains with the same auxotype/serotype/plasmid profile were subdivided by DNA amplification fingerprinting, and vice versa. CONCLUSION: Although auxotype/serotype class and DNA amplification fingerprinting can be used in the epidemiologic characterization of strains, DNA amplification fingerprinting offers a better discriminatory index than the separate serotyping. It is especially useful for differentiating serologically identical strains and nontypable strains. A combination of serotyping and DNA amplification fingerprinting seems to be the best way to differentiate Neisseria gonorrhoeae strains in epidemiologic studies, bringing together the most simple techniques and the best discriminatory power among isolates.
Three cases of paracoccidioidomycosis observed in 1990-1991 in Quillabamba, Peru, and its surroundings are described. The climate and the living conditions of the inhabitants favour paracoccidioidomycosis. It can be assumed that a majority of cases could not be identified, because the symptoms are disguised as other tropical diseases. The application of ketoconazole to the patients showed different results, from optimal to scarce, while temporary remission of the disease was obtained with itraconazole. The best therapy for paracoccidioidomycosis appears to be the application of amphotericin B plus sulphamidics.
Tonin is an enzyme of the serine protease family present in different rat tissues which releases angiotensin II (AII) directly from angiotensinogen and the tetradecapeptide renin substrate and from angiotensin I (AI). Tonin potentiates the effect of norepinephrine (NE) in the rat mesenteric artery preparation and in the aortic strips from normal and hypertensive rats. In rabbit aortic and mesenteric artery strips tonin potentiates the effect of NE, almost doubling its response. A similar effect was observed on the KCl and AII-induced contraction. This tonin-induced potentiation is reversible and long-lasting, persisting for 1 to 2 hours after being added into the tissue bath. In 75% of the vascular strips assayed, tonin elicited a contraction with a short latency period and with a maximum tension ranging from a few milligrams to over 1 g. To clarify the mechanisms of tonin effect on vascular smooth muscle, a variety of agents have been used. Neither indomethacin, saralasin, nor alpha- or beta-adrenergic blockers changed the direct contraction or the potentiation induced to NE. Db-cAMP and theophylline blocked the potentiation to the response to NE. A Ca2+-free medium, La3+, and verapamil produced a 75% inhibition of the direct tonin-induced contraction. Papaverine, isoproterenol, and theophylline relaxed the same contraction. Enzymatic inactivation of tonin blocked completely the direct contraction but not the potentiation to NE. These experiments suggest that the vasoactive effect of tonin may be mediated by the release of intracellular-bound calcium, an effect dependent on a proteolytic effect of tonin, and by increasing the cellular permeability to calcium, which is not of a proteolytic effect. It is suggested that tonin remains attached to the vascular strips by mechanisms as yet not clarified.
Tonin infused intravenously at a rate of 12 micron g/kg/min for 2 hours stimulated aldosterone and corticosterone secretion in conscious rats. In pentobarbital-anesthetized rats treated with dexamethasone and morphine, tonin stimulated aldosterone secretion, but corticosterone was unaffected. Tonin did not stimulate steroidogenesis in isolated rat adrenal glomerulosa cells unless substrate, in the form of "stripped" rat plasma, was added, in which case large amounts of immunoreactive angiotensin II were generated. These results suggest that tonin may generate an angiotensin peptide in vivo, which in turn stimulates aldosterone secretion. ACTH is secreted in response to tonin infusion, and contributes to the adrenal response.
One of the main differences between atrial and ventricular cardiocytes is the presence in former of specific granules with morphological characteristics very similar to secretory granules found in peptide-secreting endocrine cells. It has been suggested that these granules are the storage place for the atrial natriuretic factor. In the rat, water deprivation produces an increase in atrial granularity but a significant decrease in acid-extractable diuretic and natriuretic activity, suggesting that the number of atrial specific granules does not necessarily represent natriuretic activity. The atrial natriuretic factor activity is destroyed by incubation with several proteases and does not inhibit the sodium-potassium ATPase, suggesting that the active substance is a small peptide that is probably different from the so-called natriuretic hormone. After a series of chromatographic steps in Sep-Pak cartridges, Bio-Gel P-10, CM Bio-Gel, and Mono S columns, the specific activity of the atrial natriuretic factor was increased from 193, corresponding to atrial homogenates, to 242,000, which corresponds to the last chromatographic step representing a 1250-fold purification. This material showed a potent natriuretic activity, as 10 picomoles increased natriuresis by 100%.
The purpose of this study was to identify diabetes care and education issues for Latinos with diabetes. Four focus groups of Latinos with diabetes were held in the Detroit area; these sessions were audiotaped. An expert panel of bilingual health professionals from the United States and Mexico reviewed the audiotapes and identified and prioritized 47 issues using a modified Delphi technique. The highest priority issue identified by a wide margin was the difficulty many Latina women with diabetes have with self-care because of other family responsibilities. Universal diabetes care issues have a specific cultural expression which, when identified, can be incorporated into diabetes care and education programs for a particular cultural group. Focus groups are a useful means for identifying and illuminating such issues.
The objective of this study was to quantify the magnitude of iron deficiency in the postoperative period after open aortic surgery. This was a prospective observational study in 55 consecutive patients. Blood samples were obtained on postoperative days 1, 2, 4, 30, and 45, and the parameters determined were the following: iron, transferrin, transferrin saturation index, transferrin-soluble receptor, ferritin, red cell count, hemoglobin, hematocrit, serum C-reactive protein, fibrinogen, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and number of blood units transfused. We performed statistical ANOVA test for repetitive measurements (lower bound) in regard to its basal level. Iron deficiency and its parameters reached the maximum at 48 hours postoperatively (iron: 18.92 g/dL and transferrin saturation index: 11.1%) (P <.05). There was not a complete recovery after 45 days (iron: 51.23 g/dL and transferrin saturation index: 18.0%) (P <.05). A similar evolution was observed in the other measured parameters (red cell count: 3.5 x 106/L.; hemoglobin: 10.4 g/dL; hematocrit: 30.7%) (P <.005), none affecting the values of concentration or volume (P <.05). Transferrin-soluble receptors, normal at first, were increased at postoperative days 30 and 45 (2.7 and 2.4 mg/dL respectively, P <.005). After open aortic surgery there is an important acute-phase reaction, a dramatic iron deficiency, and a lack of its transporters until the 45th analyzed day. The elevation of transferrin-soluble receptors in the 4th and 6th weeks denotes a necessity of iron supplementation for a correct development of the immature hematic cells since blood parameters do not reach normal levels in the 6th postoperative week.
The presence, distribution, and levels of phospholipase A2 and ATPases activities in those structures of the guinea pig spermatozoa that participate in the acrosome reaction were studied, both before and after capacitation, as well as during the acrosome reaction induced in vitro. Spermatozoa were collected from the cauda epididymis and incubated in the absence and presence of 1.15 mmol/L calcium, with and without the addition of 1 mumol/L A23187. Membrane fractions were recovered by vortexing and discontinuous sucrose density gradient centrifugation. Most of the Na+, K(+)-ATPase was recovered in the acrosome-free spermatozoa, but a clear, distinct presence of this enzyme was observed in the plasma membrane (25 against 101 nmoles Pi released per milligram of protein, respectively). The activity of this enzyme in the periacrosomal plasma and in the outer acrosomal membrane increased during calcium incubation. Ca2(+)-dependent ATPase was found in both membrane fractions, being higher in the periacrosomal plasma membrane. The addition of calcium induced a significant inhibition of this acrosomal ATPase, whereas the activity in the acrosome-free spermatozoa increased. The activity of phospholipase A2, under all experimental conditions, was found to be restricted to the soluble fraction.
Explore the source record for details and available documents.
BACKGROUND/AIMS: The prognostic relevance of histopathologic findings in gastric carcinoma is well established. Studies on DNA-ploidy are still scanty and contradictory. METHODOLOGY: Histopathologic parameters, DNA ploidy and S-phase were evaluated in 78 cancer patients curatively resected, using formalin-fixed paraffin-embedded tissue. RESULTS: Thirty-nine tumors (50%) were aneuploid. No significant correlation was found between histologic data and ploidy, but tumors with nodal involvement were more frequently aneuploid. In univariate analysis, tumor location (p=0.05), tumor size (p=0.01), differentiation grade (p=0.02), Lauren classification (p=0.01), deeper infiltration of gastric wall (p=0.001), nodal affectation (p=0.0000) and number of lymph nodes (p=0.01), TNM stage (p=0.0000), type of gastrectomy performed (p=0.04), and DNA ploidy (p=0.04) significantly influenced survival. S-phase values had no effect on prognosis. In the multiple regression model, factors independently associated with survival were TNM stage (p=0.0009), nodal affectation (p=0.01) and, marginally, ploidy (p=0.08). CONCLUSIONS: In gastric carcinoma curatively resected, the more relevant prognostic factors were stage and nodal involvement. Fifty percent of the tumors were aneuploid. Aneuploidy was significantly associated with poorer prognosis.
This paper describes a comparative analysis of (ADL) and (IADL) items administered to two samples, 4,430 persons representative of older Americans, and 605 persons representative of patients with rheumatoid arthrisit (RA). Responses are scored separately using both Likert and Rasch measurement models. While Likert scoring seems to provide information similar to Rasch, the descriptive statistics are often contrary if not contradictory, and estimates of reliability from Likert are inflated. The test characteristic curves derived from Rasch are similar despite differences between the levels of disability with the two samples. Correlations of Rasch item calibrations across three samples were .71, .76, and .80. The fit between the items and the samples, indicating the compatibility between the test and subjects, is seen much more clearly with Rasch with more than half of the general population measuring the extremes. Since research on disability depends on measures with known properties, the superiority of Rasch over Likert is evident.
Severe necrotic cutaneous ulcers and kidney involvement secondary to type I cryoglobulinemia can be a therapeutic challenge. Plasmapheresis has been reported useful to treat autoimmune diseases such as thrombotic thrombocytopenic purpura, systemic lupus erythematosus, myasthenia gravis and Goodpasture's syndrome. We report the case of a patient who presented necrotic lesions with kidney involvement due to type I cryoglobulinemia (Ig G kappa) that evolved to a multiple myeloma. Treatment with high doses of corticosteroid plus cyclophosphamide did not control the disorder. Therapy with plasmapheresis produced a marked decrease in cryoglobulin levels and a subsequent relevant clinical improvement of cutaneous lesions and renal function. In cryoglobulinemia, plasmapheresis can be used as effective adjunt therapy to minimize cutaneous, renal and/or neurologic involvement.