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Biomedical subjects

A Montoya

Publications and source records attributed to A Montoya.

At least 19 recordsLinked to original sources

Seroprevalence to bovine virus diarrhoea virus and other viruses of the bovine respiratory complex in Venezuela (Apure State).

Six hundred and fifteen serum samples obtained from cows in five districts of Apure State, Venezuela, were tested by ELISA for antibodies to bovine virus diarrhoea virus (BVDV). The same samples were also ELISA-tested for antibodies to bovine herpesvirus type 1 (BHV-1) and bovine respiratory syncytial virus (BRSV). Additionally, the haemagglutination-inhibition (HI) test was used for detecting antibodies to parainfluenza virus type 3 (PIV-3). Overall, seroprevalence to BVDV was 36+/-7% (SE); seroprevalence varied by district (19-42%). BHV-1 seroprevalence was 67+/-4%; variation by district was similar to that of BVDV. However, the first 80 serum samples tested by BHV-1 ELISA all had a strong background reaction with the control antigen. Therefore, these sera were adsorbed to a homogenate of non-infected bovine kidney cell line (MDBK) and retested by ELISA. The non-specific reactivity was significantly reduced (p<0.001 by Wilcoxon's signed-rank test). Compared to the virus-neutralisation (VN) test, the adsorbed BHV-1 ELISA showed 94% agreement and gave a kappa value of 0.84, indicating that the adsorption did not interfere with test accuracy. Seroprevalence against BRSV was 85+/-3%, and showed differences across districts. Most of the cows (94+/-2%) were seropositive to PIV-3, and there were no significant differences among districts.

Animals

Determination of carbaryl, carbofuran and methiocarb in cucumbers and strawberries by monoclonal enzyme immunoassays and high-performance liquid chromatography with fluorescence detection. An analytical comparison.

Carbaryl, carbofuran and methiocarb are three of the most important N-methylcarbamate pesticides. In the present work, the application of laboratory-developed monoclonal antibody-based enzyme-linked immunosorbent assays (ELISAs) to the determination of these compounds in fruits and vegetables is described. Cucumbers and strawberries were spiked with the three carbamates at 10, 50 and 200 ppb. After extraction and clean-up, samples were analyzed by immunoassay and by HPLC with post-column derivatization and fluorescence detection (US Environmental Protection Agency Method 531.1). Results obtained by ELISA correlated well with those obtained by HPLC, both in terms of accuracy and precision. Recoveries were in the 60-90% range by ELISA and in the 50-90% range by HPLC, depending on the particular combination of commodity, pesticide, and fortification level under consideration. ELISAs were also applied to the analysis of non-purified sample extracts with excellent results: recoveries close to 100% were obtained, while maintaining similar precision values. This approach avoids the use of solid-phase extraction columns, saves time, and considerably increases the sample throughput. Results clearly indicate that the developed immunoassays may be suitable for the quantitative and reliable determination of carbaryl, carbofuran and methiocarb in fruits and vegetables even without including clean-up steps. These considerations make these ELISAs very useful analytical tools for monitoring and regulatory programs, without the need of complex and expensive instrumentation.

Antibodies, Monoclonal

Development of monoclonal ELISAs for azinphos-methyl. 1. Hapten synthesis and antibody production.

The development of monoclonal antibody-based enzyme-linked immunosorbent assays for azinphos-methyl is described. A panel of haptens was synthesized for immunoconjugate preparation, and a series of haptens for heterologous, coating or tracer, conjugates was also prepared. Hapten synthesis was based on a strategy in which only a fragment of the whole target molecule was present (fragmentary haptens). From immunized mice, a set of monoclonal antibodies was obtained and ELISA sensitivities were assayed in different formats. Affinities estimated as I(50) values in the low nanomolar range for azinphos-methyl and phosmet were observed for several monoclonal antibodies in the conjugate-coated format and in the antibody-coated format under nonoptimized assay conditions.

Animals

Development of monoclonal ELISAs for azinphos-methyl. 2. Assay optimization and water sample analysis.

Two enzyme-linked immunosorbent assays (ELISA) for the insecticide azinphos-methyl have been optimized and characterized. Both ELISAs are based on monoclonal antibodies produced from an immunogen with a hapten containing a phthalimido moiety and on protein conjugates of heterologous ligands containing a 1,2,3-benzotriazine group. Assay I was performed in the conjugate-coated ELISA format and assay II in the antibody-coated format. Several physicochemical factors (ionic strength, pH, incubation times, and Tween 20 and BSA concentrations) that influence assay performance were studied and optimized. Regarding specificity, both monoclonal immunoassays highly cross-reacted with azinphos-ethyl and phosmet. Finally, both assays were applied to the analysis of azinphos-methyl in spiked real water samples. For assay I the sensitivity, estimated as the I(50) value, was 0.40 nM, with a practical working range between 0.10 and 1.75 ng/mL and a limit of detection of 0.05 ng/mL. For assay II the sensitivity was 1.01 nM, with a practical working range between 0.32 and 2.54 ng/mL and a limit of detection of 0.08 ng/mL.

Antibodies, Monoclonal

Human immunodeficiency virus antibody testing by enzyme-linked fluorescent and western blot assays using serum, gingival-crevicular transudate, and urine samples.

The aim of the present study was to evaluate the possible utilization of saliva and urine as alternative samples to serum for the diagnosis of human immunodeficiency virus (HIV) infection. A total of 302 individuals participated in the study: 187 HIV-infected individuals (106 had Centers for Disease Control and Prevention [CDC] stage II infection, 19 had CDC stage III infection, and 62 had CDC stage IV infection) and 115 noninfected persons (46 of the noninfected persons were blood donors and 69 belonged to a group at high risk of HIV infection). Paired saliva and urine samples were taken from each of the participants in the study. The presence of HIV-specific antibodies was detected by an enzyme-linked fluorescent assay (ELFA), and the result was confirmed by Western blot analysis (WB). The ELFA with saliva gave maximum sensitivity and specificity values, while ELFA had lower sensitivity (95.2%) and specificity (97. 4%) values for detection of HIV antibody in urine samples. WB with all saliva samples fulfilled the World Health Organization criterion for positivity, while only 96.8% of the urine samples were confirmed to be positive by WB. Among the four reactivity patterns found by WB of these alternative samples, the most frequent included bands against three groups of HIV structural proteins (was ENV, POL, and GAG). The reactivity bands most frequently observed were those for the proteins gp160 and gp120. The least common reactivity band was the band for protein p17. The detection of HIV antibodies in saliva samples by means of ELFA with the possibility of later confirmation by WB makes saliva an alternative to serum for possible use in the diagnosis of infection. In contrast, HIV antibody detection in urine samples by the same methodology (ELFA) could be taken into consideration for use in epidemiological studies.

AIDS Serodiagnosis

Sub- and supercritical fluid extraction of trichloropyridinol from soil prior to immunoassay.

A comparative study on the extraction of TCP (3,5,6-trichloro-2-pyridinol, a metabolite of chlorpyrifos) from soil with CO2 and H2O is reported. The polarity of the analyte requires the presence of both a cosolvent (methanol) and an ion-pair reagent [(1R)-(-)-10-camphorsulfonic acid ammonium salt] for 95% extraction in 30 min when supercritical CO2 at 40 degrees C and 383 bar is used as extractant. Subcritical water (250 degrees C and 200 bar) enables complete extraction within 15 min without additives. Quantitation of the target analyte is performed by specific immunoassay using a non-commercial monoclonal antibody which provides a linear determination range between 0.005 and 5 micrograms/g, with coefficients of variation of 5.3 and 4.9% for the SC-CO2 and sub-H2O extractions, respectively.

Chromatography, Gas

A comparative study by the enzyme-linked immunofiltration assay of solid phases used in the development of flow immunosensors.

The application of an inert membrane-based, enzyme-linked immunofiltration assay (ELIFA) to the characterization of immunosorbents suitable for flow immunosensor development is described. For direct assays, eight monoclonal antibodies (MAb) raised against the insecticide carbaryl were immobilized on three sorbents, namely, controlled pore glass (CPG), hydrazide derivatized agarose beads and a hydrophilic polymer with immobilized Protein A/G. The interaction between immobilized antibodies and antigen was directly detected using a carbaryl hapten conjugated to horseradish peroxidase. Immunosorbent characterization was based on both sensitivity and re-usability. Optimal immunosorbent regeneration was achieved using 0.1 M glycine/HCl, pH 2.0 as the desorbent solution. The best covalent immunosorbent was obtained by immobilizing LIB-CNA36 MAb on hydrazide derivatized agarose beads. The best immunosorbent obtained by reversible immobilization was LIB-CNH45 MAb on Protein A/G. Using this support the eventual irreversible denaturation of covalently immobilized MAbs was overcome. For indirect assays, N-hydroxisuccinimide derivatized agarose beads and glutaraldehyde-activated CPG were used as sorbents for hapten immobilization via the amino groups of a carrier protein. In this format, antigen-MAb interactions were detected using a peroxidase-conjugated rabbit anti-mouse immunoglobulin. The highest sensitivity was achieved by LIB-CNH45 MAb in combination with derivatized agarose beads. All these results demonstrated the suitability of ELIFA as a fast, precise and easy-to-use technique for immunosorbent selection.

Biosensing Techniques

Effect of HeartMate left ventricular assist device on cardiac autonomic nervous activity.

BACKGROUND: Clinical performance of a left ventricular assist device is assessed via hemodynamic parameters and end-organ function. This study examined effect of a left ventricular assist device on human neurophysiology. METHODS: This study evaluated the time course change of cardiac autonomic activity of 3 patients during support with a left ventricular assist device before cardiac transplantation. Cardiac autonomic activity was determined by power spectral analysis of short-term heart rate variability. The heart rate variability before cardiac transplantation was compared with that on the day before left ventricular assist device implantation. RESULTS: The standard deviation of the mean of the R-R intervals of the electrocardiogram, an index of vagal activity, increased to 27 +/- 7 ms from 8 +/- 0.6 ms. The modulus of power spectral components increased. Low frequency (sympathetic activity) and high frequency power (vagal activity) increased by a mean of 9 and 22 times of each baseline value (low frequency power, 5.2 +/- 3.0 ms2; high frequency power, 2.1 +/- 0.7 ms2). The low over high frequency power ratio decreased substantially, indicating an improvement of cardiac sympatho-vagal balance. CONCLUSIONS: The study results suggest that left ventricular assist device support before cardiac transplantation may exert a favorable effect on cardiac autonomic control in patients with severe heart failure.

Adult

Arterial impedance in patients during intraaortic balloon counterpulsation.

BACKGROUND: Symptomatic improvement of a patient's hemodynamic condition during intraaortic balloon counterpulsation (IABC) is considered to result largely from a reduction in afterload. Afterload can be accurately quantified by arterial input impedance measurements. Here we report the effect of IABC on arterial impedance in humans. METHODS: To characterize the effects of IABC on arterial input impedance, impedance measurements were obtained using aortic annulus Doppler flow and pressure from the aortic balloon catheter. Impedance spectra were compared between the cardiac cycles preceding and following the cycle with IABC in 25 patients. RESULTS: Intraaortic balloon counterpulsation increased stroke volume (23%; p = 0.001), reduced myocardial oxygen demand (11%; p = 0.02), and decreased the aortic pressure at the onset of systole (16%; p = 0.001). There was also a decrease in systemic vascular resistance (24%; p = 0.001), characteristic arterial impedance (21%; p = 0.002), and pulse wave reflection (20%; p = 0.006). Linear regression analysis showed that an increase in stroke volume was predicted only by the decrease in systemic vascular resistance (r = -0.81; p = 0.001). CONCLUSIONS: The reduction in systemic vascular resistance appeared to be the major mechanism by which IABC improved cardiac pumping efficiency. This effect may result from the passive distention of the peripheral vascular bed due to the propagation of the balloon-augmented diastolic pressure through the arterial system.

Aged

Natural history of allograft coronary arteriopathy: a retrospective study of 54 patients over a 8 1/2-year period.

A total of 288 patients underwent heart transplantation at Loyola University Medical Center over a 8 1/2-year period starting in March, 1984. Of these patients, 54 were identified as having allograft coronary arteriopathy. Diagnosis was made on the basis of abnormal findings on coronary angiography in 44 patients; either an autopsy or explanted heart revealed the diagnosis in the remainder. A total of 279 abnormal lesions were identified by coronary angiography, and over 70% of these stenoses were discrete and located in large epicardial vessels. The left ventricular ed-diastolic pressure demonstrated a steady rise over time (2.5 mmHg/year), and also correlated with the degree of allograft coronary arteriopathy stenosis. The rate of stenosis progression was 33% per year from the time of initial allograft coronary arteriopathy development. Actuarial survival rate was lower than that of patients with arteriopathy. In conclusion, first, the majority of allograft coronary arteriopathy stenoses detected on coronary angiography are discrete, involve large epicardial vessels, and progress rapidly over time. Second, left ventricular end-diastolic pressure seems to reflect the degree of allograft coronary arteriopathy stenosis, and may prove to be a useful indicator of left ventricular dysfunction related to allograft coronary arteriopathy. Third, patients with allograft coronary arteriopathy show a decreased actuarial survival rate.

Actuarial Analysis

Topography of cardiac ganglia in the adult human heart.

Published descriptions of the topography of cardiac ganglia in the human heart are limited and present conflicting results. This study was carried out to determine the distribution of cardiac ganglia in adult human hearts and to address these conflicts. Hearts obtained from autopsies and heart transplant procedures were sectioned, stained, and examined. Results indicate that the largest populations of cardiac ganglia are near the sinoatrial and atrioventricular nodes. Smaller collections of ganglia exist on the superior left atrial surface, the interatrial septum, and the atrial appendage-atrial junctions. Ganglia also exist at the base of the great vessels and the base of the ventricles. The right atrial free wall, atrial appendages, trunk of the great vessels, and most of the ventricular myocardium are devoid of cardiac ganglia. These findings suggest modifications to surgical procedures involving incisions through regions concentrated with ganglia to minimize arrhythmias and related complications. Repairs of septal defects, valvular procedures, and congenital reconstructions, such as the Senning and Fontan operations, involve incisions through areas densely populated with cardiac ganglia. The current standard procedure for orthotopic heart transplantation severs cardiac ganglia and their projections to nodal and muscular tissue. One modification of the current heart transplantation procedure, involving bicaval anastomosis, preserves atrial anatomy and the cardiac ganglia. Preservation of cardiac ganglia within the donor heart may provide additional neuronal substrate for intracardiac processing and targets for regenerating nerve fibers to the donor heart.

Adult

Post-lung transplant biopsies: an 8-year Loyola experience.

A total of 125 transplant procedures involving the lung have been performed at Loyola University of Chicago in 120 patients. There were 67 single (40 right, 27 left), 44 bilateral single, 2 double lung, and 12 heart-lungs (HL) transplant procedures. This paper summarizes the pathologic findings in 565 transbronchial, 102 endobronchial, 20 open lung, and 92 endomyocardial biopsies and compares them with the recommendations in the published literature. The lung biopsies were evaluated according to the Working Formulation, Lung Rejection Study Group, International Society of Heart Transplantation. In transbronchial biopsies, all of which were from the transplanted lungs, the number of alveolated lung fragments ranged from 0 to 14 (mean, 5). Two hundred twelve biopsies showed no rejection, 113 had minimal rejection, 133 had mild rejection, 34 had moderate rejection, and 1 had severe acute rejection. Active airway damage (Grade B) was seen in 48 biopsies, which were graded from minimal to severe based on the amount of inflammation. Chronic rejection (Grade C) was diagnosed in 23, chronic vascular rejection (Grade D) in 8, and acute vasculitis (Grade E) in 9 biopsies. Routine trichrome and elastic van Gieson stains did not add to the diagnosis. All biopsies were routinely stained with immunoperoxidase for cytomegalovirus. Cytomegalovirus was diagnosed in 84 biopsies, 54 by both H&E and immunoperoxidase, 23 by immunoperoxidase alone, and 5 by H&E alone. The endobronchial biopsy of the anastomotic site had nonspecific inflammation in 46 biopsies. Twenty-nine had infection with a specific organism, Aspergillus and Candida in each of 8 biopsies by Gomori's methenamine silver stain, cytomegalovirus in 7 (4 by H&E and immunoperoxidase; 3 by immunoperoxidase), bacteria in 4, and fungal hyphae in 2 biopsies. In the 12 patients with heart-lung transplants, a total of 92 endomyocardial, 35 transbronchial, and 1 endobronchial biopsies were obtained. Acute rejection was seen only in 2 endomyocardial biopsies, whereas the transbronchial biopsy showed acute mild or moderate rejection in 10, chronic rejection in 1, and cytomegalovirus infection in six biopsies. We conclude that: (a) all biopsies with alveolated lung parenchyma can be evaluated for rejection and infection yielding clinically significant diagnoses; (b) sections from three levels stained by H&E are essential for evaluation; (c) routine Gomori's methenamine silver, elastic van Gieson, and trichrome stains are not required for transbronchial biopsy, however, routine Gomori's methenamine stain is recommended for all anastomotic site biopsies; (d) routine immunoperoxidase for cytomegalovirus is extremely helpful; (e) Grade B rejection should be further graded; and (f) endomyocardial biopsy played no significant role in the management of heart-lung recipients.

Acute Disease

Postmortem findings in lung transplant recipients.

Lung transplantation is now an accepted modality for treating end-stage lung disease. To better understand the factors limiting the survival of these patients, we reviewed the autopsy findings in 37 patients who received lung transplants. Between 1986 and 1995, 131 patients have undergone lung transplantation at our institution, including 4 patients with repeat transplantations. Of these, 48 (36.6%) died, 37 (77%) of whom had an autopsy. The autopsied patients were divided into three groups on the basis of post-transplantation interval: early (< 30 d), intermediate (31-365 d), and late (> 365 d). Of the 12 patients in the early group, 6 died of intra- and postoperative complications and 6 of bacterial infection with pneumonia in the transplanted lung. There were 18 patients in the intermediate group, of whom 11 died of infection (5 of cytomegalovirus, 5 of nonviral infections of the transplanted lung, and 1 of encephalomyelitis), 3 of post-transplantation lymphoproliferative disorder, 3 of chronic airway rejection, and one of unrelated cause. Of the seven patients in the late group, four died of chronic airway rejection, two of unrelated causes, and one of bacterial infection. Native lungs examined in 23 patients showed, in addition to the primary disease, bacterial pneumonia in 5, post-transplantation lymphoproliferative disorder in 3, cytomegalovirus in 2, and aspergillosis in 1. In this series of 37 autopsied patients, chronic rejection was the cause of death in 7 and was concomitantly seen in 3 patients (27%). In summary, the most common cause of death was infection (48%), followed by chronic rejection (19%), surgical complications (19%), post-transplantation lymphoproliferative disorder (7%), and unrelated causes (7%); rejection was not a major cause of death in the early and intermediate post-transplantation periods; in 30% of native lungs, significant pathologic findings were present in addition to the primary disease; and in the intermediate post-transplantation period, significant left ventricular hypertrophy occurred, which may be attributable to cyclosporine-induced hypertension but which needs to be further studied.

Adolescent

DNA flow cytometry of canine mammary tumours: the relationship of DNA ploidy and S-phase fraction to clinical and histological features.

The DNA ploidy status and S-phase fraction (SPF) of benign proliferative lesions (BPL) and malignant tumours (MT) in the mammary glands of dogs were determined by flow cytometric analysis and the results were related to their clinical and histological features. Seven (14.3 per cent) of 49 BPL and 16 (48.5 per cent) of 33 primary MT had aneuploid G0,1 peaks (P < 0.001). Hypodiploid G0,1 peaks were found in one BPL and in five primary MT. The DNA ploidy status of primary MT was not found to be associated with their size, nodal status, grade of histological malignancy or nuclear grade. In several cases there was intra-tumour heterogeneity in ploidy status independent of histological heterogeneity. The SPF was significantly higher in 27 primary MT than in 45 BPL when diploid and aneploid cases were combined for comparison (P < 0.05), but not when only diploid cases were compared. Among the primary MT the SPF was higher in aneuploid than in diploid tumours (P < 0.05) and it was higher in five MT from five dogs with regional disease than in 22 MT from 19 dogs with local disease (P < 0.05). The SPF was positively correlated with the grade of histological malignancy (P < 0.05) but not with nuclear grade.

Animals

Chronic cardiac rejection masking as constrictive pericarditis.

The hemodynamic changes consistent with constrictive pericarditis are often encountered in patients who have undergone cardiac transplantation. We describe here 4 patients who underwent pericardiectomy after cardiac transplantation. All were found to have evidence of a thickened and constricting peel of pericardium at surgical exploration. Their postoperative clinical courses were variable. One patient with primarily effusive constriction experienced marked improvement. Three patients failed to show clinical improvement and had persistently elevated atrial and ventricular end-diastolic pressures. A coexisting restrictive cardiomyopathy secondary to chronic rejection, coronary arteriopathy, or long-standing constriction may have been the cause of this poor outcome. Many patients with transplanted hearts exhibit evidence of poor diastolic ventricular compliance without evidence of classic constriction; some manifest both the restrictive and constrictive components. The careful selection of patients with constrictive pericarditis can optimize the outcome.

Adult

Survival and functional outcome after single and bilateral lung transplantation. Loyola Lung Transplant Team.

BACKGROUND: The experience at Loyola University Chicago was retrospectively reviewed to evaluate survival and functional outcome after single lung transplantation (SLT) and bilateral lung transplantation (BLT). METHODS: Ninety patients underwent lung transplantation at Loyola University Chicago between April 1990 and December 1993. Mean age was 45 years (range, 13 to 66 years). Fifty percent were male. Pre-lung transplant pulmonary diseases were as follows: emphysema and/or chronic obstructive pulmonary disease in 43 patients, pulmonary fibrosis in 13, cystic fibrosis in 14, pulmonary hypertension in eight, repeated transplantation for obliterative bronchiolitis in four, bronchiectasis in two, bronchoalveolar cell carcinoma in two, sarcoidosis in one, primary obliterative bronchiolitis in one, histiocytosis X in one, and lymphangiomyomatosis in one. Fifty-seven patients underwent SLT, and 33 had BLT. Maintenance immunosuppression medications consisted of cyclosporine, azathioprine, and prednisone. RESULTS: Perioperative complications were as follows: seven of 33 patients bled after BLT, and two of 57 bled after SLT. Bronchial complications were found in six of 66 (9%) BLT anastomoses and eight of 57 (14%) SLT anastomoses. Nine operative deaths occurred in SLT patients: six from allograft failure, one from infection, one from intrapulmonary hemorrhage, and one from bronchial dehiscence. Only two patients died in the perioperative period after BLT and that was of infection. Three late deaths occurred after BLT, all as a result of infection; 13 recipients died late after SLT: five of infection, four patients from lymphoma, two of pancreatitis, one of tension pneumothorax, and one of pulmonary embolism. For the entire patient population the actuarial 1- and 2-year survival rates were 72% and 68%, respectively. One-year survival rates were significantly better for patients undergoing lung transplantation for obstructive and nonrestrictive lung diseases than those of patients undergoing lung transplantation for vascular or restrictive pulmonary disease. Recipients of BLT had a trend toward better survival than recipients of SLT. Lung function 6 months after transplantation measured by forced expiratory volume in 1 second was significantly better in BLT than SLT, 71% of predicted versus 54%. CONCLUSIONS: Patients who undergo BLT have significantly better postoperative pulmonary function than those who undergo SLT. On the basis of the study there was a trend toward better survival with BLT.

Adolescent

The Loyola University lung transplant experience.

BACKGROUND: We reviewed our experience with isolated lung transplantation at Loyola University Medical Center, Maywood, Ill. From April 1990 through June 1992, 33 lung transplantations for end-stage pulmonary disease were performed (30 single lung, three bilateral single lung). Recipient diagnoses include chronic obstructive pulmonary disease, alpha 1-antiprotease deficiency, pulmonary fibrosis, primary pulmonary hypertension, Eisenmenger's syndrome, sarcoidosis, cystic fibrosis, bronchiectasis, and bronchiolitis obliterans. METHODS: For patients who underwent transplantation for end-stage obstructive airway disease, we retrospectively reviewed functional indexes before and after transplantation. In addition, the overall survival rate was determined. RESULTS: Successful transplantation resulted in a marked improvement in functional capacity. Single-lung transplantation for end-stage obstructive airway disease resulted in a threefold improvement in the 1-second forced expiratory volume, from 0.49 to 1.64 L. The actual survival for all isolated lung transplant recipients (including both single-lung and bilateral single-lung procedures) was 73%, with a 15% 30-day mortality. CONCLUSION: Isolated lung transplantation can significantly improve functional capacity as well as the quality of life in patients with end-stage lung disease.

Actuarial Analysis