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C Montero

Publications and source records attributed to C Montero.

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

Fibrosing mediastinitis: CT and MR findings.

The aim of this study is to present the computed tomography (CT) and magnetic resonance (MR) findings in three cases of fibrosing mediastinitis, probably secondary to tuberculosis. Two patients had diffuse involvement of the mediastinum and one patient presented with a posterior mediastinal mass. On CT, the patients with diffuse involvement showed infiltrating soft-tissue masses with multiple foci of dense calcifications. One of these lesions enhanced mildly with contrast and one did not enhance. On MR examination, diffuse masses were of heterogeneous, intermediate and low signal on T1-weighted images (n = 2) and were of homogeneous low signal (n = 1) or heterogeneous (n = 1) signal intensity on T2-weighted images. After administration of Gd-DTPA, these mediastinal masses showed heterogeneous enhancement. The posterior mediastinal mass showed homogeneous pronounced enhancement on CT and was homogeneous with intermediate T1 signal intensity and hypointense T2 signal intensity. The CT findings of an infiltrative or well-defined mediastinal mass with scattered calcifications should suggest the diagnosis of fibrosing mediastinitis in the appropriate clinical setting. Although the appearance of calcification on MR are not specific, this technique provides further information than CT especially in those cases in which the lesions appear noncalcified, because MR imaging revealed areas of low signal intensity characteristic of fibrous tissue.

Adult↗
PubMed1998

Field studies and cost-effectiveness analysis of vaccination with Gavac against the cattle tick Boophilus microplus.

The control of tick infestations and the transmission of tick-borne diseases remains a challenge for the cattle industry in tropical and subtropical areas of the world. Traditional control methods have been only partially successful and the parasites continue to result in significant losses for the cattle industry. Recently, vaccines containing the recombinant Boophilus microplus gut antigen Bm86 have been developed. These vaccines have been shown to control tick infestations in the field. However, extensive field studies investigating the efficacy and cost-effectiveness of vaccination have not been reported and are needed to appraise the effect of this new approach for tick control. Here is reported the results of the application of Gavac in a field trial including more than 260,000 animals in Cuba. In this study the correlation between the antibody response to vaccination and the effect on ticks fertility is determined. Physiological status of the animals was found to affect the primary response to vaccination but not the antibody titers after revaccination. A cost-effectiveness analysis showed a 60% reduction in the number acaricide treatments, together with the control of tick infestations and transmission of babesiosis, which resulted in savings of $23.4 animal-1 year-1. These results clearly demonstrate the advantage of vaccination and support the application of Gavac for tick control.

Animals↗
PubMed1998

Effect of particulation on the immunogenic and protective properties of the recombinant Bm86 antigen expressed in Pichia pastoris.

The recombinant Bm86 tick antigen expressed in Pichia pastoris is obtained in a highly particulated form, as a distinguish feature of this expression system. This particulated protein, the active principle of the recombinant vaccine Gavac against the cattle tick, have shown high immunogenic and protective properties, probably associated with its own characteristics. To evaluate the effects of particulation on the properties of Bm86, three groups of calves were immunized with particulated or non-particulated recombinant Bm86 and the anti-Bm86 antibody response determined. Animals were challenged with a controlled tick infestation and the protective capacities of both proteins assessed. Humoral immune response and protection in cattle vaccinated with the particulated antigen were higher. These experiments suggested that particulation of the Bm86 expressed in P. pastoris is an important feature for the protective properties of the antigen in vaccine preparations.

Animals↗
PubMed1996

Clinical experience with retrograde lung preservation.

Previous reports and our own experimental work suggest increased vascularity of the tracheobronchial wall when retrograde lung preservation is used. This principle was clinically applied in 21 consecutive lung transplant recipients (10 single and 11 bilateral). Lung preservation was achieved via the left atrial appendage and drainage was obtained through the pulmonary artery. Pneumoplegic preservation was achieved with modified Euro-Collins solution. Cardioplegia was induced by the standard method and the heart, harvested by different teams, did not exhibit left ventricular dilatation. Thirty-two bronchial anastomoses without wrapping were performed. No primary lung graft failure was documented. Cardiopulmonary bypass was instituted in three cases of pulmonary hypertension; however, this was deemed unnecessary in the remainder of the cases of bilateral transplantation while the second organ was being implanted. All bronchial anastomoses were followed between 2 and 28 months. A single instance of bronchial anastomosis dehiscence was observed on the 30th postoperative day. However, no stents were employed in this series, and no strictures or anastomotic granulomas have been reported so far. All the hearts could be used satisfactorily except for one primary graft failure. In conclusion, retrograde lung preservation is feasible in clinical lung transplantation, with simultaneous harvesting of the heart. The impact of retrograde lung preservation on the late clinical outcome remains to be seen.

Anastomosis, Surgical↗
PubMed1996

Thermal stability of Artemia HGPRT: effect of substrates on inactivation kinetics.

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT, E.C.2.4.2.8) from Artemia cysts exhibits maximum activity at 70 degrees C. Its thermal stability has been examined following enzymatic activity as a function of temperature. Cold-induced renaturation experiments of samples heated at increasing temperatures showed that reversibility of thermal inactivation depends on the incubation time and final temperature. Prolonged incubation of the thermoinactivated enzyme at 0 degree C did not afford any further increase of the catalytic activity at 37 degrees C. The complex substrate PRPP:Mg protects HGPRT from thermal inactivation. However, incubations with hypoxanthine rendered a less thermostable enzyme at any temperature tested. The irreversible inactivation of HGPRT proceeds in two exponential steps. The analysis of the apparent rate constants for the fast and the slow phases, lambda 1 and lambda 2 as per the Lumry and Eyring model suggests the existence of more than three states in the thermal denaturation pathway of the free enzyme. In the presence of PRPP:Mg the irreversible process follows a single exponential and proceeds very slowly below 70 degrees C. PRPP:Mg also protects the enzyme from inactivation by NEM and pCMB, suggesting that -SH groups may be in the vicinity of the active site.

Animals↗
PubMed1996

[Urate production in a porcine model of myocardial ischemia-reperfusion].

OBJECTIVE: This study was designed to investigate urate production by swine hearts using an in vivo regionally ischemic-reperfused model. ANIMALS AND METHODS: Ten female pigs underwent 60 minutes of myocardial ischemia by clamping of the left anterior descending artery and afterwards 120 minutes of reperfusion. Epicardial biopsies and blood samples from coronary sinus were taken before ligation, at the end of ischemic period and 5, 30, 60 and 120 minutes upon reperfusion. RESULTS: During ischemia, tissue levels of ATP and ADP greatly declined with a subsequent increase in the concentration of AMP, inosine and hypoxanthine (33 +/- 12 vs 93 +/- 17, 26 +/- 8 vs 768 +/- 86 and 32 +/- 10 vs 219 +/- 26 nmol/g dry weight, p < 0.01 for each). Despite the great increase in the hypoxanthine levels, uric acid concentration remained constant (69 +/- 9 vs 32 +/- 12 nmol/g dry weight, NS). Hypoxanthine, xanthine and uric acid concentrations increased in blood samples obtained from the coronary sinus at the end of ischemic period (17.99 vs 31.03 nmol/ml, p < 0.01, 0.29 vs 1.45 nmol/ml, p < 0.05 and 1.20 vs 2.31 nmol/ml, p < 0.01 respectively) and were enhanced upon reperfusion (35.8 and 3.89 nmol/ml for hypoxanthine and uric acid respectively, p < 0.05) without any significant modifications in their concentrations at the arterial level. CONCLUSION: These results demonstrate that the ischemic-reperfused swine heart produces urate probably outside the myocardium.

Animals↗
PubMed1996

[Segmental portal hypertension and cystic tumor of the pancreas].

Isolated obstruction of the splenic vein constitute 5-10% of all patients with portal hypertension. The evaluation of splenic vein patency is important in assessing inflammatory or neoplastic diseases of the pancreas. Accurate preoperative diagnosis is therefore essential to allow the correct choice of operative procedure. A case of isolated splenic vein obstruction with left-sided portal hypertension secondary to cystadenocarcinoma of the pancreas is reported in order to discuss criteria of preoperative diagnosis between benign and malignant cystic lesions of the pancreas.

Adult↗
PubMed1996

The influence of salts on the reaction between hGH and several of its monoclonal antibodies in fixed, paraffin-embedded human pituitary as a model system.

A study of the influence of three salts of monovalent cations (Nacl, KCl, and CsCl) and three salts of divalent cations (MgCl2.6H2O, anhydrous CaCl2, and SrCl2.6H2O), on the specific reaction between human hGH and three of its monoclonal antibodies has been carried out, using human pituitary glands obtained at autopsy as a model system. This study is an attempt to find out the physico-chemical laws ruling the immunohistochemical reaction in the special circumstance of fixed specimens, where the antigen (Ag) is immobilized in the tissue substrate, while the antibody (Ab) is mobile. Our interpretation of the results points to a reaction of the salts with side groups of aminoacids in the paratope (specific saline effect) and a mass salt effect on the reaction kinetic proper that is dependent on the salt concentration. The high affinity coefficient of the in situ Ag-Ab reaction is shown, at the immunohistochemical level, by the high molarity necessary to make the reaction negative. Also, it seems there is a direct relationship between the critical molarity values obtained and the affinities of the monoclonal antibodies used in this study.

Antibodies, Monoclonal↗
PubMed1995

Demonstration of induction of erythrocyte inosine monophosphate dehydrogenase activity in Ribavirin-treated patients using a high performance liquid chromatography linked method.

The activity of inosine monophosphate dehydrogenase (IMPDH: EC 1.2.1.14) was measured in erythrocyte lysates using a non-radiolabelled method linked to reversed-phase liquid chromatography (RPLC). The mean activity in erythrocytes from healthy controls using this sensitive method was extremely low (mean 85 pmol/h per mg protein, range 4-183). The elevated erythrocyte IMPDH activity reported previously in hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency was confirmed (mean 234 pmol/h per mg protein). Erythrocyte IMPDH activity of patients with other disorders of purine metabolism, or with leukaemias and lymphomas, showed no marked difference from controls, except in one instance--an immunodeficient child with purine nucleoside phosphorylase (PNP) deficiency, treated with Ribavirin, where a 30-fold increase in activity was found (2670 pmol/h per mg protein). Investigation of erythrocyte IMPDH in other immunodeficient children with normal PNP activity demonstrated that this grossly elevated erythrocyte activity was attributable to induction of IMPDH by Ribavirin therapy.

Antimetabolites↗
PubMed1995

Chronic pneumomediastinum and subcutaneous emphysema: association with dermatomyositis.

We describe a 41-year-old patient with adult-onset dermatomyositis who developed persistent pneumomediastinum and severe subcutaneous emphysema due to end-stage interstitial lung disease. The diagnosis of dermatomyositis was based on proximal muscle weakness, electromyographic findings of inflammatory myopathy, and positive findings on muscle biopsy. Low levels of creatine kinase elevation were found at the time of diagnosis (a form of dermatomyositis which has been associated with a poor prognosis). The patient had no signs of cutaneous vasculitis. Despite treatment with prednisone and azathioprine, she died of intercurrent gram-negative sepsis 15 months after the diagnosis of dermatomyositis.

Adult↗
PubMed1994

Diacetyl for blocking the histochemical reaction for arginine.

Two different histochemical methods for blocking the guanidinium group of arginine in formalin fixed, paraffin embedded material are reported here. One procedure uses diacetyl with short incubation times and high pH, the other uses the trimer of the diacetyl reagent and requires longer incubation times but moderate pH. The diacetyl reagent is recommended despite its high pH because the preparation of the diacetyl trimer is laborious and time-consuming.

Arginine↗
PubMed1993

Ultrastructural and immunocytochemical characteristics of hepatocytes from hepatitis B virus infected chimpanzees.

Liver tissue samples from four chimpanzees submitted to viral challenge in order to test a recombinant anti-hepatitis B virus vaccine, were studied by electron microscopy. The vaccinated monkeys showed no evidences of acute viral hepatitis (AVH), demonstrating the protection against an infective viral dose; on the contrary, the non-vaccinated chimps developed signs of AVH in hepatocytes such as: different size and shape, slight dilatation of the rough endoplasmic reticulum, disappearance of the mitochondrial crests, broadening of the normal space between the membranes of the nuclear coating and presence of laminar bodies and cytoplasmic vacuoles. Furthermore, the presence of the hepatitis B virus surface (HBV) antigen was confirmed in non-vaccinated monkeys using immunocytochemical techniques. Transmission electron microscopy and immunocytochemical analysis corroborated the protective effect of the recombinant vaccine against the HBV in the vaccinated animals.

Animals↗
PubMed1992

A novel route of ATP synthesis.

Incorporation of the adenine moiety of 2'-deoxyadenosine (dAdo) into ATP, consistently observed in human erythrocytes, is a phenomenon which cannot be explained by the operation of any known pathway. We reported previously that this effect was not observed in adenine phosphoribosyltransferase-deficient erythrocytes showing that adenine must be an obligatory intermediate. However, generation of adenine from dAdo was difficult to reconcile with the operation of any known process in human cells, and involvement of S-adenosylhomocysteine hydrolase (SAH-hydrolase) was postulated. The present studies with intact human erythrocytes demonstrate that nucleoside analogues which inhibit SAH-hydrolase caused substantial attenuation of adenine transfer from dAdo into ATP. It was confirmed that dAdo is not a substrate of 5'deoxy-5'methylthioadenosine (5'MT-adenosine) phosphorylase. Inhibition of the transfer of the adenine moiety of dAdo into ATP did not correlate with inhibition of 5'MT-adenosine phosphorylase by nucleoside analogues. This report provides further evidence that the pathway involving nucleoside (adenosine) analogue binding to SAH-hydrolase, release of base and subsequent phosphoribosylation can operate in intact cells. The metabolic significance of this process relates to the possible generation of free bases (adenine) in the human body, ATP synthesis and nucleoside drug interconversions.

Adenosine Triphosphate↗
PubMed1992

Quantitative changes in the frequency and distribution of the C-cell population in the rat thyroid gland with age.

The development of calcitonin cells (C-cells) was investigated in rat thyroid glands from birth to 120 days, using an immunoperoxidase technique and a point-counting method. The proportion of C-cells to follicular cells was 4.5% on the day of birth and increased progressively to 10.4% by 120 days. The highest density of C-cells was noted in the mid-region of the lobes along a longitudinal axis. The caudal and cephalic regions of the lobes contained smaller numbers of C-cells. The C-cells tended to be more numerous in the posterior aspects of the lobes. Although the numbers of C-cells in 120-day-old animal were markedly increased as compared to animals at the time of birth, the cell distributions within the glands were similar at all ages.

Aging↗
PubMed1992

Randomized trial of chemotherapy versus chemotherapy plus radiotherapy for stage III-IV A & B Hodgkin's disease.

A total of 151 patients with previously untreated Hodgkin's disease, clinical stages III-IV A & B, were randomized to receive CVPP for 6 cycles, or CVPP plus RT 3000 cGy to previously involved areas between the 3rd and 4th cycles. CVPP consists of cyclophosphamide 600 mg/m2/i.v., vinblastine 6 mg/m2/i.v. on day 1, procarbazine 100 mg/m2/p.o. and prednisone 40 mg/m2/p.o. on days 1 to 14. Both groups displayed similar clinical characteristics at diagnosis. Sixty-six were treated with CVPP + RT (52 St III and 14 St IV) and 85 with CVPP alone (68 St III and 17 St IV). Complete remission was obtained in 57 (86%) of 66 patients who received CVPP plus RT, and in 62 (73%) of 85 patients treated with CVPP. Five and sixteen patients, respectively, achieved partial responses, while 2 in each group died during treatment. At 7 years, duration of complete remission and failure-free survival were: 51% and 45% for those treated with CVPP plus RT, and 23% and 21% with CVPP alone (p = 0.0150 and P = 0.0016, respectively). Overall survival at 7 years was 71% and 58%, respectively (p = 0.1488). A dose analysis performed in 84 pts showed that 91% and 88% received full protocol doses of CPM and PCZ, respectively, in the CVPP + RT group, and 95% and 94% for CVPP. The WBC nadir was 3.5 and 3.7 x mm3, respectively. Of 25 pts on CVPP + RT who relapsed, 9 are now disease-free, 5 are alive with disease and 11 have died, and with CVPP, of 37 relapsing pts, 18 are disease-free, 5 are alive with disease and 14 are dead.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Effects of adenosine analogues on ATP concentrations in human erythrocytes. Further evidence for a route independent of adenosine kinase.

Adenosine derivatives are frequently used in chemotherapy because of their potent antitumor, antiviral and antiparasitic activity. We investigated the metabolism of some adenosine analogues in adenosine deaminase inhibited normal and adenine phosphoribosyltransferase (APRT) deficient human erythrocytes. The ATP and GTP concentrations and the formation of unusual nucleotides were measured. Some of the analogues studied (tubercidin, 9 beta-D-arabinofuranosyladenine, 2'-deoxyadenosine, 2-chloroadenosine, neplanocin A) were phosphorylated to the corresponding nucleoside triphosphates and this process was abolished by iodotubercidin--an adenosine kinase inhibitor. With the exception of 2'-deoxyadenosine, nucleotide analogue formation was accompanied by ATP depletion. ATP decrease was not observed after adenosine kinase inhibition and ATP concentration even increased in the presence of 2'-deoxyadenosine, neplanocin A and 5'-iodo-5'-deoxyadenosine. However, the latter increment was not observed in APRT deficient erythrocytes. Bredinin, S-adenosylhomocysteine, deoxycoformycin and adenosine dialdehyde did not form nucleotide derivatives or exert any effects on ATP concentration. It is concluded that adenosine analogues can either enter the nucleotide pool via phosphorylation mechanisms, or may be converted to ATP by the pathways involving the intermediate formation of adenine.

Adenine Phosphoribosyltransferase↗
PubMed1991

Further studies on the purine phosphoribosyltransferase 'burst' velocity reaction.

In the assays used to determinate the adenine and hypoxanthine-guanine phosphoribosyltransferases activities from Artemia cysts two phases of velocity are observed in the synthesis of AMP, IMP and GMP: one initial burst and a second, slower, steady-state velocity. Both reaction velocities are divalent cation-dependent and temperature-resistant, as they are detectable at temperatures from 0 to 100 degrees C. Butanol, frequently employed to interrupt the purine phosphoribosyltransferase reactions, does not inhibit the enzyme activities. The 'burst' phase is not detected when the reaction is ended by the addition of EDTA. These data support that the initial velocities of these enzymatic reactions may be due to the accumulation of products formed by the overall reaction, developed subsequent to the controlled reaction period, being the 'burst' a result from the relative resistance of these enzymes to the agents that are often used to stop the reaction, such as heat or butanol.

Animals↗