Effect of mitomycin-C on the bioavailability of the radiopharmaceutical (99m)technetium-phytic acid in mice: a model to evaluate the toxicological effect of a chemical drug.

The many desirable characteristics of technetium-99m ((99m)Tc) have stimulated the development of labelling techniques for different molecular and cellular structures. It is generally accepted that a variety of factors can alter the biodistribution of radiopharmaceuticals and one such factor is drug therapy. Because patients on chemotherapeutic treatment receive a radiopharmaceutical in a nuclear medicine procedure, we have studied in Balb/c mice the effect of mitomycin-C on the biodistribution of the radiopharmaceutical (99m)Tc-phytic acid ((99m)Tc-PHY) used in hepatic scintigraphy. Mitomycin-C is an antineoplastic agent obtained from Streptomyces caesptosus and is used on the treatment of disseminated adenocarcinoma of the stomach or pancreas. Three doses of mitomycin-C were administered via the ocular plexus into Balb/c mice. One hour after the last dose, (99m)Tc-PHY was administered and the animals were sacrificed. The organs were isolated, the radioactivity was determined in a well counter and the percentages of radioactivity in the organs were calculated. The results have shown that the percentage radioactivity has been increased in stomach, spleen, lung, thyroid and bone, decreased in pancreas and thymus and not altered in ovary, uterus, kidney, heart, liver and brain. The changes in the distribution of (99m)Tc-PHY may be the result of metabolic processes and/or therapeutic actions produced by the administration of mitomycin-C.     

Prospective evaluation of the role of quantitative Doppler ultrasound surveillance in liver transplantation.

Doppler ultrasound (DUS) is able to measure parameters of blood flow within vessels of transplanted organs, and vascular complications are associated with abnormal values. We analyzed the findings of 51 consecutive patients who underwent DUS on 2 occasions in the first postoperative week following liver transplantation for cirrhosis to determine the range of values in patients following liver transplantation. Three patients developed early vascular thromboses that were detected by the absence of a Doppler signal. In patients making an uneventful recovery, the arterial velocity tended to increase and the resistive index (RI) to decrease during the first postoperative week. All recipients were shown to have high-velocity segments within the hepatic artery, without an increase in flow resistance. Assessment of the portal vein revealed narrowing at the anastomosis, associated with a segmental doubling of flow velocity, and the mean portal venous flow decreased by approximately 20% in the first postoperative week. In conclusion, a wide range of abnormalities occurs in the vessels of liver transplant recipients, which were not associated with the development of vascular complications or affect patient management.     

Schistosoma mansoni: preclinical studies with 9-Acridanone-hydrazones in Cebus monkeys experimentally infected.

Derivatives of acridine (9-Acridanone-hydrazones) were tested in Cebus monkeys experimentally infected with Schistosoma mansoni, at the dosages of 50, 25, and 12.5 mg/kg (p.o., single dose). At least, four compounds seemed to be very promising, promoting alterations in the oogram and reducing the worm burden drastically, even at the lowest dose (12.5 mg/kg). No side effects could be detected after drug administration.     

Vincristine in steroid-resistant nephrotic syndrome

The therapeutic response to vincristine was examined in seven children (aged 2–15 years) with corticosteroid-resistant (CR) nephrotic syndrome (NS) with focal and segmental glomerulosclerosis (FGS). Five were also resistant to cyclophosphamide. Vincristine was given weekly (1.5 mg/m² intravenously) for 8 weeks. Simultaneously, prednisone (60 mg/m² per day, orally) was given for 4 weeks and then gradually tapered. Two of these patients had a complete and stable remission; in five no benefit was observed. It was not possible to identify any characteristics to predict the response to vincristine. Although there is a case for trying vincristine therapy in CR NS with FGS, the results of this study are not encouraging and a better understanding of its action and indications is necessary.     

Concerning the reaction of zirconocene dichloride and methylalumoxane: Homogeneous Ziegler-Natta catalytic system for olefin polymerization

The interaction of zirconocene dichloride (Cp₂ZrCl₂) with methylalumoxane (MAO), the two components of homogeneous catalyst for olefin polymerization, was studied by ¹H NMR spectroscopy. Its was found that Cp₂ZrCl₂ is monoalkylated by Al₂(CH₃)₆ present in MAO. The trimethylaluminium contained in MAO appears to be the active species in the alkylation of the zirconocene dichloride. The Cp₂ZrCH₃Cl likely forms, with an excess of MAO, highly polarized species. These are decomposed by a complexing agent of MAO such as KCl.     

Value of transesophageal echocardiography in the diagnosis of acute aortic dissection]

We describe our experience of six patients with clinical suspicion of acute aortic dissection (AAD) who were studied consecutively by transesophageal echocardiography (TEE) from April to July of 1991. All of them were previously submitted to transthoracic echocardiogram. The diagnosis was correctly established by TEE in five cases, confirmed by aortography and/or surgery (four cases), or by autopsy (one case). In one patient the diagnosis of AAD was excluded by TEE, and posteriorly by nuclear magnetic resonance. Four patients had a Stanford type A, and one patient a type B dissection. The site of entry was identified in three cases; the intimal entry tear of the type B dissection, not observed by TEE, was localized in the aortic arch by aortography. In three of the four type A dissection cases, a thrombus in the false lumen and an aortic regurgitation were found. No other noninvasive methods were used after the diagnosis of AAD by TEE. The surgical repair was successful in three cases, one of which, without previous necessity of aortography. In our experience, TEE increased extraordinarily the diagnosis efficacy of AAD, making possible an earlier therapeutic approach, and probably contributing to the improvement of the prognosis of this pathology.     

Malignant teratoma of the thyroid: case report.

Teratomas in the neck are rare neoplasms. Most of them occur in infants less than 1 year and are benign. In contrast, thyroid teratomas in adults are malignant and have fatal outcomes because of spread of tumor refractory to treatment. We report a case of a primary thyroid malignant teratoma in a 37-year-old woman. She was treated successfully with a combination of surgery, postoperative cis-platinum-based chemotherapy, and radiation therapy to the neck. Although the time of follow-up is short (24 months), we attribute her successful outcome to the use of this intensive therapeutic approach.     

Biliary strictures complicating liver transplantation. Incidence, pathogenesis, management, and outcome.

Six hundred sixty-six patients received 792 liver transplants between February 1, 1984 and September 30, 1991. Biliary reconstruction was by choledochocholedochostomy (CDCD) with T-tube (n = 509) or Roux-en-Y choledochojejunostomy (CDJ) (n = 283). Twenty-five patients (4%) developed biliary strictures. Anastomotic strictures were more common after CDJ (n = 10, 3.5%) than for CDCD (n = 3, 0.6%). Intrahepatic strictures developed in 12 patients. Six patients had occult hepatic artery thrombosis (HAT). The other six patients received grafts in which cold ischemia time exceeded 12 hours. Anastomotic strictures were successfully managed by percutaneous dilation (PD) in five patients (n = 10), operation in three (n = 6), with retransplantation required in two patients. Intrahepatic strictures were managed by PD in seven, retransplantation in one, and expectantly in four patients. Of 25 patients, 19 (76%) are alive with good graft function. In three of six deaths, the biliary stricture was a significant factor to the development of sepsis and allograft failure. The authors conclude that (1) anastomotic strictures are rare after LT; (2) the development of biliary strictures may signify occult HAT; (3) PD is effective for most strictures; and (4) extended cold graft ischemia (less than 12 hours) may be injurious to the biliary epithelium, resulting in intrahepatic stricture formation.