[Benign fibrous mesothelioma: report of 8 cases]

Benign fibrous mesothelioma (BFM) is a primary, isolated tumor of the pleura. In 80% of patients the tumor originates in the visceral pleura. BFM is rare and localized malignant mesothelioma, whose prognosis and treatment is significantly different, must be considered as a differential diagnosis. We report 8 cases of BFM excised by thoracotomy. In 6 asymptomatic patients, diagnosis was based on radiological images. One patient with a large tumor suffered dyspnea, acropachia and hypertrophic osteoarthropathy. The last patient experienced long-lasting chest pain even though the tumor was small (3 x 3 x 1 cm). Diagnosis was before thoracotomy in 3 cases, 2 by punch biopsy (tru-cut) and the other by thoracoscopy. The results of pleural fluid analysis were nonspecific in 2 of the 3 cases in which pleural effusion was present. Thoracotomy allowed removal of the entire tumor in all patients.

The bovine IFN-omega 1 is biologically active and secreted at high levels in the yeast Pichia pastoris

The gene coding for bIFN-omega 1 was isolated from bovine genomic DNA by polymerase chain reaction (PCR). Recombinant bIFN-omega 1 was expressed in the yeast Pichia pastoris and high levels of the recombinant protein (0.4 mg ml-1) were secreted to the culture media. The obtained bIFN-omega 1 showed a cross-species antiviral activity on four mammalian cell lines of calf, pig, hamster and human origin, but this activity was absent on Madin-Darby canine kidney (MDCK) cells. A delivery carrier was developed to permit a better release of bIFN-omega 1. When compared with a control group, an increase in 6 days in the corpus luteum lifespan was obtained in cyclic ewes following three interferon (IFN) intrauterine administrations on days 9, 10 and 11 post-estrus. In summary, these results demonstrated for the first time that biologically active recombinant bIFN-omega 1 was highly secreted by P. pastoris showing antiviral activity in different cell lines and an antiluteolytic effect in cyclic ewes, with no detrimental effects on the animals.

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.

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.

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.

[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.

[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.

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.

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.

Ecology of Triatoma rubrovaria (Hemiptera, Triatominae) in wild and peridomestic environments of Uruguay

This paper describes population structure, spatial distribution and habitat selection of wild and peridomestic populations of Triatoma rubrovaria (Blanchard, 1843). Field studies were carried out at Las Piedras and La Bolsa in the Northern Department of Artigas, Uruguay. A semicircular sampling area, divided in seven or eight triangular sectors was sequentially examined from October 1990 to November 1991. At Las Piedras (typical wild habitat) 1063 T. rubrovaria bugs were collected from 84% of the rocky outcroops ("pedregales"). Abundance varied by season peaking in October-November (spring). Throughout the year, most of the population was made up of third, fourth and fifth instar nymphs; adults were found from October to March. In the peridomestic environment of La Bolsa, however T. rubrovaria was less common and showed a more irregular instar distribution. Colonized ecotopes, were those close to houses. In both sites T. rubrovaria was mainly associated with the geckonid Homonota uruguayensis and the cockroach Blaptica dubia.

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.

[Feeding pattern of Triatoma rubrovaria (Blanchard, 1843) (Hemiptera, Triatominae) in peridomiciliary habitats, of a rural area of Uruguay]

It has been studied the feeding patterns of Triatoma rubrovaria (wild triatominae bug, and intradomiciliary secondary vector of T. cruzi) in a rural area of "La Bolsa" (Department of Artigas). Agar double diffusion test were used for analyze the blood meal, from 120 insects, which were confronted to 13 antisera. It has 251 identify blood meals, and the most frequently was mammalian host (73%), but it has a variable source of feeding (mammals, birds, reptiles and cockroach), including humans rate 8% of the total. The identify of haemolimphe as feed, place this triatominae bug as an intermediary vector between predator and haematophagous. The most usual mammals are dasypodides and bovines. The frequence of human blood meal near the dwellings, shows its potentiality as vectors. Therefore, the peridomicile is an area of interaction between, domestic, wild and sinantropic host. The trypanosomic infection's rate at peridomiciles was lesser those at wild areas.

Laparoscopic and histologic findings in patients with the human immunodeficiency virus

Hepatic dysfunction frequently develops in patients infected with the human immunodeficiency virus (HIV). This retrospective study was undertaken to determine the laparoscopic and histologic findings in a group of HIV-seropositive patients with or without the acquired immune deficiency syndrome (AIDS). Fifty-four patients, 44 with AIDS and 10 HIV-positive, underwent laparoscopic examination and visually guided biopsies for the assessment of clinical or biochemical evidence of liver injury. Significant abnormalities were detected in 31/44 (70%) AIDS patients and 3/10 (30%) HIV-positive patients. Overall, specific laparoscopic findings were described in 25/54 (46%). The most common findings were peritoneal involvement, massive intra-abdominal adhesions, focal lesions of the liver or spleen, and diffuse nodularity of the liver; these were usually related to opportunistic infections or neoplasms such as non-Hodgkin's lymphomas and Kaposi's sarcoma. No procedure-related deaths occurred. Laparoscopy is a safe and accurate method to detect underlying disease in a selected population of HIV-seropositive patients.

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.

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.

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.