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Biomedical subjects

A A Garcia

Publications and source records attributed to A A Garcia.

14 recordsLinked to original sources
PubMed1997

Tapping mode Atomic Force Microscopy of scleroglucan networks.

Tapping mode Atomic Force Microscopy (TmAFM) has been used to study the fungal polysaccharide scleroglucan deposited from aqueous solution and dimethyl sulfoxide (DMSO) onto a mica surface. The solutions from which the microscope samples were produced were prepared by first dissolving the solid scleroglucan in 0.1M NaOH, then neutralizing the solution with HCl, followed by dilution to the required concentration in either water or DMSO. It was found that from the aqueous solution described above, scleroglucan forms networks. Based on a comparison of the denatured-renatured and aqueous solution samples, network formation is due to the imperfect registration between the chains forming the triple helices. The relatively large stiffness of the scleroglucan triple helix is also assumed to contribute to the formation of the extended networks. The triple helix diameter was measured to be 0.92 +/- 0.27 nm, which is in the same range as that obtained by other researchers using similar techniques. Denatured scleroglucan, deposited from DMSO onto mica, forms a web-like layer on top of which there are sphere-like structures. These morphologies are believed to be due to triple helix denaturation yielding highly flexible single chains in DMSO, which results in coiling and web-like dense packing of scleroglucan upon deposition onto mica. Most interestingly after additional of water to the samples deposited from DMSO, some of the chains can be renatured into short, stiff rod-like structures which are similar to the structures observed by others researchers. The imaging data for aqueous solution deposition can be analyzed by plotting maximum end-to-end distance versus the perimeter of the networks deposited onto mica. This yields a Flory-like exponent of 0.67, which is almost similar in value to that obtained by other researchers for linear structures of scleroglucan but less than that expected for a polymer chain following a self-avoiding walk (upsilon = 0.75) model on a two-dimensional surface. The fractal dimension that can be used to characterize the networks was determined graphically to be 1.22 +/- 0.06.

Carbohydrate Conformation↗
PubMed1996

Xanthogranulomatous cystitis as a cause of elevated carcinoembryonic antigen mimicking recurrent colorectal cancer. Report of a case.

We report a case of xanthogranulomatous cystitis that developed in a patient with a history of colon cancer. While undergoing adjuvant chemotherapy with fluorouracil and levamisole, rising carcinoembryonic antigen (CEA) levels and the appearance of a pelvic mass, suspicious for recurrent cancer, were identified. Exploratory laparotomy demonstrated the presence of a benign condition of the bladder, xanthogranulomatous cystitis, which was resected by partial cystectomy. CEA levels have normalized. This is the first reported case of xanthogranulomatous cystitis producing an elevated CEA level.

Carcinoembryonic Antigen↗
PubMed1995

Ifosfamide-induced Fanconi syndrome.

OBJECTIVE: To report a case of possible ifosfamide-induced Fanconi syndrome in and adult with cancer. CASE SUMMARY: A 20-year old man was treated for an osteosarcoma with a chemotherapy regimen that included ifosfamide, methotrexate, and doxorubicin. Three months after completing therapy he developed polyuria, polydypsia, and bilateral ankle pain. Laboratory findings showed decreased serum concentrations of phosphorus, uric acid, calcium potassium, and bicarbonate; elevated blood urea nitrogen and creatinine; and increased urinary excretion of phosphorus, potassium, calcium, citrate, and protein. The patient was diagnosed with Fanconi syndrome and osteomalacia. Treatment with oral supplements of potassium, sodium, citric acid, calcium, and calcitriol corrected the electrolyte abnormalities. DISCUSSION: The adverse effect most frequently associated with ifosfamide is hemorrhagic cystitis. The incidence of hemorrhagic cystitis is decreased with the concomitant administration of the uroprotective agent mesna. The development of Fanconi syndrome after ifosfamide therapy has been described previously, although it occurs more frequently in children than adults. the mechanism by which ifosfamide causes renal tubular damage is not well understood, but it appears to involve metabolites of the drug. CONCLUSIONS: The development of renal tubular defects and renal failure should be considered in patients receiving ifosfamide. Although this complication appears more frequently in children, adults also can be affected. Renal function should be monitored closely to detect the appearance of this adverse effect. Renal tubular dysfunction can, as this case illustrates, develop months after completing chemotherapy.

Adult↗
PubMed1993

BCG cell imaging using scanning probe microscopy.

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) were used to obtain images of the surface of whole, intact BCG (bacille Calmette Guerin, a mycobacterium) cells in air and under solution by immobilizing the cells onto glass slides (AFM only) or highly oriented pyrolytic graphite. The technique used for AFM imaging involved depositing a submonolayer of cells under a centrifugal force followed by fixation/dehydration using polar organic solvents. AFM images agree well with images from light and electron microscopy and showed large numbers of BCG cells in their distinctive cord arrangement. The AFM also proved useful for identifying extracellular microgranules which cannot be seen with light microscopy. For STM imaging, the hydrophobicity of BCG enabled strong adhesion from aqueous solution onto graphite. STM images of BCG could only be obtained while scanning in aqueous solution, and the cells showed a large variation in contrast when different samples were imaged. The STM provided greater detail of surface features than the AFM and was able to produce images of periodic layers corroborating observations made by transmission electron microscopy.

Microscopy↗
PubMed1989

Lymphokine production by blood or spleen mononuclear cells from patients with schistosomiasis mansoni.

Peripheral blood mononuclear cells (PBMN) from individuals with active or former intestinal schistosomiasis mansoni or splenocytes from patients with the hepatosplenic form of the disease were evaluated for their ability to generate chemotactic factors for neutrophils in response to schistosomal antigenic preparations derived from adult worms (SWAP), eggs (SEA), or phytohemagglutinin (PHA). When supernatants from cultures of stimulated PBMN from normal donors were assayed, only those obtained from cells which had been cultured in presence of PHA displayed chemotactic activity for neutrophils. In contrast, supernatants from cultures of SWAP or SEA stimulated PBMN from patients with intestinal or hepatosplenic schistosomiasis were shown to contain chemotactic activity for neutrophils from normal individuals. PBMN from persons who previously had been infected with Schistosoma mansoni but had received chemotherapy years before presented a pattern of response to SWAP or SEA similar to those from patients with active infections. The response of splenocytes from patients with hepatosplenic schistosomiasis was considerably different from PBMN from individuals with active or with treated schistosomiasis. Splenocytes from most of those patients with hepatosplenic disease failed to produce chemotactic factors for neutrophils in response to stimulation with at least 1 of the schistosome antigens tested. These results indicate that the lymphocytes from schistosomiasis mansoni patients are able to recognize and are stimulated by adult worm and egg antigens to produce chemotactic substances for neutrophils, and that this ability persists for many years after chemotherapy with schistosomicidal drugs. At the hepatosplenic stage, immunoregulatory mechanisms, which may prevent the production of chemotactic factors by splenocytes and/or their activity upon neutrophils in vitro, seem to occur.

Adult↗
PubMed1989

Epithelioid hemangioendothelioma of the liver with myocardial metastases.

Epithelioid hemangioendothelioma is an unusual type of endothelial-derived vascular tumor located mainly in the soft tissues of the limbs. The present report describes a 48-year-old woman with an epithelioid hemangioendothelioma located in the liver with very unusual metastases to the myocardium. While the disease itself was controlled by adriamycin the patient died as a consequence of portal hypertension due to the abundant fibrotic component distinctive of this type of tumor. An epithelioid appearance can sometimes lead to a mistaken diagnosis of metastatic carcinoma, as happened initially in our case. The endothelial origin of the tumor must be confirmed by electron microscope identification of Weibel-Palade bodies or by immunohistochemical staining of factor VIII-related antigen. To the authors knowledge, this is the first case of myocardial metastases from an epithelioid hemangioendothelioma of the liver to be reported in English in the medical literature.

Female↗
PubMed1986

Immune responses during human schistosomiasis mansoni. XIII. Immunological status of spleen cells from hospital patients with hepatosplenic disease.

Splenocytes from 25 patients with severe hepatosplenic schistosomiasis mansoni were obtained after therapeutic splenectomy. Spleen cells were phenotyped and analysed for responsiveness to mitogens or heterogeneous schistosome-derived antigenic preparations (eggs, SEA; adult worms, SWAP; cercariae, CERC) in blastogenesis assays and lymphokine production systems, and were compared with peripheral blood mononuclear cells (PBMN). Splenic lymphocytes were 55% T lymphocytes (sheep erythrocyte rosette-positive) and 37% surface immunoglobulin-positive B lymphocytes. The mean T4+:T8+ ratio of these splenocytes was 1.0. Phytohaemagglutinin stimulated spleen cell production of the lymphokine mitogenic factor, but exposure to SEA or SWAP did not. Spleen cell and PBMN blastogenic responses to SEA and SWAP were sometimes, but not always in accord. Removal of plastic adherent cells allowed the non-adherent spleen cells of 30-40% of the patients to respond substantially more vigorously to SEA, SWAP and CERC. Spleen cells from a subgroup of 20-30% of the patients failed to respond to the schistosomal antigens regardless of removal of adherent cells. Spleen cell responses to gram-negative lipopolysaccharide peaked on day 5 or 6 of culture, and were augmented by adherent cell removal. Pokeweek mitogen-stimulated responses were optimal on day 5 of culture. Spleen cells from most severe, hepatosplenic schistosomiasis mansoni patients do not respond well to schistosomal antigens or B-cell mitogens. The splenic responses of many of these patients were elevated by the removal of adherent spleen cells.

Adolescent↗
PubMed1986

Immune responses during human schistosomiasis. XII. Differential responsiveness in patients with hepatosplenic disease.

Thirty-four hospitalized patients and 12 ambulatory patients, all with hepatosplenic schistosomiasis mansoni were evaluated in regard to their peripheral blood mononuclear (PBMN) cell responses to schistosomal antigenic preparations and compared with groups of 40 patients with the hepatointestinal form and 39 patients with the more common, chronic intestinal form of schistosomiasis mansoni. PBMN cell blastogenic responses were measured upon exposure to schistosomal egg antigens (SEA), adult worm antigens (SWAP) and a cercarial antigenic preparation (CERC). All groups had some individuals who did not respond to some or all of these preparations. In the hospitalized hepatosplenic group greater than 50% did not respond to SEA. Analysis of the responses in each group revealed that all responders could be subdivided into moderate and high responders. High responders to SEA had experimental minus control values of greater than 8,000 counts per minute (CPM). For SWAP and CERC, this arbitrary cut-off value was greater than 25,000 CPM and greater than 11,000 CPM, respectively. The percent of high SEA responders in the groups differed considerably. This was 23% in the chronic intestinal group, 40% in the chronic hepatointestinal group, 67% for ambulatory hepatosplenic patients and 20% for hospitalized hepatosplenic patients. Previous studies had demonstrated that 94% of patients with early (2-3 month) acute schistosomiasis mansoni were high responders to SEA and none were nonresponders. Furthermore, at the other end of the spectrum, 100% of former schistosomiasis mansoni patients (treated and cured 7-35 years previously) were high responders to SEA. None were nonresponders to any of the antigen preparations. It is proposed that during acute infection all patients express vigorous responses to SEA. Upon continued infection most patients (75%) modulate this florid response. However, continued high responders comprise 40% of the chronic hepatointestinal cases and almost 70% of the ambulatory hepatosplenic patients. These latter 2 groups may likely represent early forms of the severe clinical disease found in the hospitalized hepatosplenic patient population. Fifty percent of the hospitalized group appear anergic and no longer respond to SEA, while only 20% are high responders. Long after chemotherapy it appears that the anti-SEA regulatory mechanisms of former chronic patients have subsided, leaving strong anti-SEA responsiveness.

Acute Disease↗
PubMed1983

Prophylactic use of lidocaine to prevent advanced ventricular arrhythmias during pulmonary artery catheterization. Prospective double-blind study.

To determine whether prophylactic lidocaine could decrease the incidence of advanced ventricular arrhythmias, 62 patients undergoing 67 pulmonary artery catheterizations were given lidocaine or placebo before and during catheterization. Advanced ventricular arrhythmias occurred in 42 of the 67 catheterizations (63 percent). In 18 of 31 patients receiving lidocaine (58 percent) arrhythmias developed, whereas 24 of 36 patients who received placebo (67 percent) had evidence of arrhythmias. These differences were not significant. However, patients with catheterization times of less than 20 minutes who were treated with lidocaine had less ectopy (25 percent) than patients treated with placebo (68 percent) (p less than 0.05). Two patients has sustained ventricular tachycardia and both were receiving placebo. No complications of lidocaine prophylaxis were noted. Prophylactic lidocaine appears to decrease the incidence of mechanically induced arrhythmias in critically ill patients undergoing catheterization that is not prolonged.

Adult↗
PubMed1982

Thyrotrophin-binding-inhibition assay: comparison of crude and purified membrane preparations.

Two different thyroid membrane preparations (TMP), crude and pure, made from a homogenate of normal human thyroid tissue, were used to test purified serum IgG from 36 patients with Graves' disease, and 10 normal control subjects, in the thyrotrophin-binding-inhibition (TBI) assay. All reagents for the assay were identical, and aliquots of each IgG were tested in both TMP simultaneously, under exactly comparable conditions. Blood was drawn while the patients were hyperthyroid (19), euthyroid (13), or hypothyroid (4); 15 of the patients were untreated and 21 were being treated. The frequency of positive TBI was similar in both TMPs and highest among the 131I-treated patients. Comparison of TBI results in both TMP for each IgG sample revealed wide differences, and 47.1% of the Graves' IgGs were TBI positive in one membrane preparation, while negative in the other. There was no correlation of TBI values between the two TMP, or with clinical status, or the presence of standard thyroid antibodies. The findings indicate that the IgGs of Graves' disease, as now tested in the TBI assay, bind heterogeneous to different fractions of the thyroid membranes.

Binding Sites, Antibody↗
PubMedDate not supplied

Strategies for the recovery of chemicals from fermentation: a review of the use of polymeric adsorbents.

Many different compounds can be produced by using microorganisms or enzymes. An important element in the design of a viable biotechnological process is the selection of an economical and efficient separations train. Production of chemicals via biotechnology generally requires isolation and purification from dilute, aqueous solution. A general framework for separation process design relies on exploiting a unique molecular physicochemical property (or properties) for separating the molecule of interest from water and the other species in solution. Important properties that can be utilized for the recovery of low molecular weight polar compounds are molecular charge, hydrophobicity, Lewis acidity or basicity, volatility, and limited solubility. In turn, it can be useful to characterize molecular properties by using separation processes, such as, for example, hydrophobicity by measuring octanol/water partition coefficients. This paper reviews the use of adsorption onto hydrophobic, nonpolar macroreticular polymers and Lewis acid-base complexation by using functionalized polymers for the recovery of amino acids, carboxylic acids, alcohols, and ketones from dilute aqueous solution. The focus will be on utilizing physical and chemical properties to predict uptake capacity. This information will be relevant to separation process development and will help to characterize molecular properties in aqueous solution.

Adsorption↗
PubMedDate not supplied

Pancreatic cancer and primary care providers.

Pancreatic cancer is a relatively uncommon neoplasm for which long-term survival is unusual. Early diagnosis can lead to prolonged survival, because successful treatment is possible with surgical resection of stage 1 tumors. However, clinical findings are nonspecific and diagnosis usually occurs at advanced stages. Radiologic and laboratory techniques can help to identify patients earlier in the course of the disease. To detect tumors in early stages, efficient and cost-effective application of clinical, laboratory, and radio-logic methods should be used. But the primary care provide must understand the general characteristics of pancreatic cancer.

Adolescent↗