Phase II trial of pemetrexed-based induction chemotherapy followed by concomitant chemoradiotherapy in previously irradiated patients with squamous cell carcinoma of the head and neck.

BACKGROUND: Concurrent chemoreirradiation therapy (CRRT) offers a therapeutic option for patients with locoregionally recurrent squamous cell carcinoma of the head and neck (SCCHN). We hypothesized that response to induction chemotherapy (IC) would improve outcome and predict increased survival. PATIENTS AND METHODS: Subjects with recurrent SCCHN not amenable to standard therapy were eligible. IC consisted of two 28-day cycles of gemcitabine and pemetrexed on days 1 and 14, followed by surgical resection, if appropriate, and/or CRRT consisting of carboplatin, pemetrexed, and single daily fractionated radiotherapy. RESULTS: Thirty-five subjects were enrolled, 31 were assessable for response, with 11 responders [response rate = 35%; 95% confidence interval (CI) 19.2-54.6]. Among 24 subjects who started CRRT, 11 were assessable for radiographic response, 4 complete response, 2 partial response, and 5 progressive disease. Median progression-free survival and overall survival (OS) were 5.5 months (95% CI 3.6-8.3) and 9.5 months (95% CI 7.2-15.4), respectively. One-year OS was 43% (95% CI 26% to 58%). Subjects who responded to IC had improved survival (P = 0.02). Toxic effects included mucositis, dermatitis, neutropenia, infection, hemorrhage, dehydration, and pain. CONCLUSIONS: The combination of pemetrexed plus gemcitabine was active and well tolerated in recurrent SCCHN. Response to IC may help stratify prognosis and offer an objective and dynamic metric in recurrent SCCHN patients being considered for CRRT.

The role of atrial vessels in aortic root and mitral valve operations.

BACKGROUND: For the last 90 years, several authors have focused on studying the blood supply to the conduction system in the human heart. However, an important gap has been maintained between this topic and cardiac surgical procedures when they should have been closely matched. This paper is aimed at clarifying the morphology of the conduction system and its blood supply and assessing its role in cardiac surgical procedures. METHODS: Twenty human hearts were dissected after antegrade and retrograde injection. After dissection, different surgical procedures were simulated. Finally, we assessed the damage that these procedures might have caused either to the conduction system or to the vessels supplying it. RESULTS: Kügel's artery, the right superior descending artery, and the sinoatrial node artery were found to be harmed by the surgical procedures performed. In all these cases, these vessels were supplying part of the conduction system. CONCLUSIONS: All the vascular structures described in the paper play a very important role in the blood supply to the conduction system, and they become vulnerable during aortic root and mitral valve surgical procedures.

Expression of trans-sialidase and 85-kDa glycoprotein genes in Trypanosoma cruzi is differentially regulated at the post-transcriptional level by labile protein factors.

To adapt to different environments, Trypanosoma cruzi, the protozoan parasite that causes Chagas' disease, expresses a different set of proteins during development. To begin to understand the mechanism that controls this differential gene expression, we have analyzed the levels of amastin and trans-sialidase mRNAs and the mRNAs encoding members of the 85-kDa glycoprotein gene family, which are differentially expressed in the T. cruzi stages found in the mammalian host. Amastin mRNA is expressed predominantly in intracellular and proliferative amastigotes. trans-Sialidase mRNAs are found mostly in forms undergoing transformation from amastigotes to trypomastigotes inside infected cells, whereas mRNAs encoding the 85-kDa glycoproteins appear only in the infective trypomastigotes released from the cells. The genes coding for these mRNA species are constitutively transcribed in all stages of T. cruzi cells, suggesting that expression is controlled post-transcriptionally during differentiation. Inhibition of transcription by actinomycin D revealed that each mRNA species has a relatively long half-life in stages where it accumulates. In the case of the trans-sialidase and 85-kDa glycoprotein genes, mRNA accumulation was induced by treatment with the protein synthesis inhibitor cycloheximide at the stages that preceded the normal accumulation. Therefore, mRNA stabilization may account for mRNA accumulation. mRNA degradation could be promoted by proteins with high turnover, or stabilization could be promoted by forming a complex with the translational machinery at defined times in development. Identification of the factors that induce mRNA degradation or stabilization is essential to the understanding of control of gene expression in these organisms.

New findings on the origin of the blood supply to the atrioventricular node. Clinical and surgical significance.

The anatomy of the heart's conduction system and of its blood supply have been research topics for many years. However, several proposals have never been demonstrated. In this paper, we describe 2 vascular conduits that have never before been objectively shown to supply the conduction system. Twenty human hearts from subjects aged between 15 and 65 years--with and without coronary disease--were dissected after anterograde and retrograde injection with latex butaclor E-650 by means of a technique developed by the authors. In 40% of these hearts, Kugel's artery was found to supply the atrioventricular node. The right descending superior artery supplied the atrioventricular node in 70% of the hearts dissected. These findings may be of major significance both in clinical cardiology and in cardiovascular surgery.

Trypanosoma cruzi: the Tc-85 surface glycoprotein shed by trypomastigotes bears a modified glycosylphosphatidylinositol anchor.

Tc-85, an 85-kDa surface glycoprotein specific for the trypomastigote stage of Trypanosoma cruzi, has been implicated in the invasion of host cells by the parasite. Radioactive palmitic acid was incorporated into Tc-85 immunoprecipitated from the culture medium with the H1A10 monoclonal antibody, suggesting that shedding occurs with Tc-85 bearing its GPI anchor. In contrast to the glycoprotein remaining in the parasites, the glycosylphosphatidylinositol moiety in shed Tc-85 is resistant to phosphatidylinositol phospholipase C and becomes susceptible to the enzyme following alkali treatment. An alkylglycerol was identified by thin layer chromatography of an ether extract after the enzymatic reaction. Resistance to cleavage by phospholipase C is due to fatty acid esterification of the inositol residue in shed Tc-85. This is the first example of inositol modification in anchors from a glycoprotein of Trypanosoma cruzi.

Turnover and shedding of the Tc-85 surface glycoprotein of Trypanosoma cruzi trypomastigotes.

Tc-85 is an 85-kDa surface glycoprotein specific for the trypomastigote stage of Trypanosoma cruzi which has been implicated in the invasion of host cells by the parasite. Tc-85 has a half-life of 3.5-4 h and is synthesized as a 95-kDa precursor. Processing of the 95-kDa precursor is inhibited by N-p-tosyl-L-lysine chloromethyl ketone, p-chloromercuriphenylsulfonic acid, iodoacetamide or N-ethylmaleimide, but not by aprotinin, antipain or phenylmethylsulfonil fluoride. Tc-85, but not the precursor, is rapidly shed into the medium, allowing a correlation between the decrease of Tc-85 in trypomastigotes and its increase in the culture medium. The shedding of Tc-85 was inhibited 50% by 1 microM tunicamycin, but not by 10 microM swainsonine or 10 microM 1-deoxynojirimycin under the experimental conditions employed. This suggests that N-linked oligosaccharides are important for the shedding phenomenon, although it appears that they do not have to be fully processed for shedding to occur.

Turnover and shedding of the Tc-85 surface glycoprotein of Trypanosoma cruzi trypomastigotes

Tc-85 is an 85-kDa surface glycoprotein specific for the trypomastigote stage of Tripanosoma cruzi which has been implicated in the invasion of host cells by the parasite. Tc-85 has a half-life of 3.5-4 h and is synthesized as a 95-kDa precursor. Processing of the 95-kDa precursor is inhibited by N-p-tosyl-L-lysine chloromethyl ketone, p-chloromercuriphenylsulfonic acid, iodoacetamide or N-ethylmaleimide, but not by aprotinin, antipain or phenylmethylsulfonil fluoride. Tc-85, but not the precursor, is rapidly shed into the medium, allowing a correlation between the decrease of Tc-85 in trypomastigotes and its increase in the culture medium. The shedding of Tc-85 was inhibited 50 per cent by 1 muM tunicamycin, but not by 10 muM swainsonine or 10 muM 1-deoxynojirimycin under the experimental conditions employed. This suggests that N-linked oligosaccharides are important for the shedding phenomenon, although it appears that they do not have to be fully processed for shedding to occur.

A surface antigen of Trypanosoma cruzi involved in cell invasion (Tc-85) is heterogeneous in expression and molecular constitution.

A monoclonal antibody (McAb), H1A10, causes 46-96% inhibition of the invasion of tissue culture cells by trypomastigotes from different strains and clones of Trypanosoma cruzi. Higher inhibition was observed when axenic medium-derived metacyclic trypomastigotes (72-96%) were employed instead of tissue culture-derived trypomastigotes (46-60%). In contrast to the metacyclic population, in which all individuals reacted with the McAb, part of the tissue-cultured trypomastigote population did not bind the antibody. The molecular masses and isoelectric points of the glycoproteins recognized by the H1A10 McAb differed when tissue culture trypomastigotes of the Y strain and YuYu strain were analyzed. Variability between the strains was also observed when the antigens were metabolically labelled in the presence of tunicamycin. These results suggest that the differences described are probably not due solely to the carbohydrate portion of the molecule.

Antigenuria in chronic chagasic patients detected by a monoclonal antibody raised against Trypanosoma cruzi.

A monoclonal antibody (B2/5) raised against Trypanosoma cruzi was able to immunoprecipitate a major 100 kDa polypeptide in 84% of the urines collected from chronic chagasic patients. Other polypeptides were also detected. The antibody recognized polypeptides on the surface of epimastigotes (150-25 kDa) and metacyclic trypomastigotes (150-50 kDa), suggesting that the antigens share a common epitope.

Partial inhibition of trypomastigote entry into cultured mammalian cells by monoclonal antibodies against a surface glycoprotein of Trypanosoma cruzi.

Monoclonal antibodies were raised against the surface of trypomastigote forms of Trypanosoma cruzi. Although some of these antibodies reacted against antigens shared by trypomastigote and epimastigote or amastigote forms, the majority were trypomastigote-specific. Trypomastigote-specific monoclonal antibodies recognized all infective stages, including trypomastigotes from the bloodstream of infected mice, insect feces, tissue culture and those resulting from differentiation of epimastigotes in axenic culture media. The monoclonal antibodies H1A10 and 6A2, as well as Fab fragments from H1A10, partially prevented T. cruzi invasion of LLC-MK2 cell monolayers (inhibition of 50-70%) when present throughout the entire experiment. Both antibodies recognized an 85 kDa glycoprotein (Tc-85) of the trypomastigote surface which contains N-acetyl-D-glucosamine and/or sialic acid.

Surface antigens of stocks and clones of Trypanosoma cruzi isolated from humans.

The total surface polypeptide pattern was analyzed after radioiodination of 12 different stocks and clones of Trypanosoma cruzi belonging to four different zymodemes isolated from humans of the region of Bambuí (M.G., Brazil). Although some minor differences were encountered, it is concluded that this pattern cannot be used as a method for classification of strains. Sera obtained from chagasic patients harboring parasites typed according to each zymodeme and from rabbits immunized with either epimastigotes or trypomastigotes from the Y strain immunoprecipitated surface antigens of apparent Mr 55 kDa, 80 kDa and 95 kDa in all the stocks (epimastigotes) tested. These antigens thus appear to be conserved among stocks of T. cruzi and to be common to epimastigotes and trypomastigotes. Immunoprecipitation of antigens of surface radioiodinated trypomastigotes (Y strain) with 16 different chagasic sera indicates a remarkable identity among the observed patterns, suggesting that the antigenic characteristics of the surface of T. cruzi infective forms are highly conserved and insensitive to the zymodeme type.