Natural killer susceptibility of brain tumor cell lines inversely correlates with the degree of cell differentiation and not with the level of human histocompatibility antigen expression

The purpose of this paper is to investigate the natural killer (NK) sensitivity of 15 cell lines derived from human brain tumors expressing different levels of major histocompatibility complex (MHC) antigens. Although it has recently been reported that NK susceptibility varies inversely with target cell class-I human leukocyte antigen (HLA) expression, our results show no correlation between class-I HLA, class-II HLA or beta 2-microglobulin expression on target cells and NK sensitivity, whereas a significant inverse correlation between NK susceptibility and the degree of tumor cell differentiation has been found. Thus, poorly differentiated tumor cells are highly susceptible to NK lysis, whereas well-differentiated ones are NK resistant. These results suggest that sensitivity to lysis by NK cells of cell lines derived from human brain tumors is primarily determined by the stage of differentiation and not by the level of MHC antigen expression on target cell.

Mitroflow heart valve: 5.5 years clinical experience

From March 1982 through December 1986, 139 Mitroflow pericardial heart valves were utilized in 129 patients. There were 69 males and 60 females, with an average age of 55.2, range 26 to 74 years. Eighty-nine patients underwent isolated aortic valve replacements, 27 isolated mitral valve replacements, 3 isolated tricuspid valve replacements, 10 mitro-aortic valve replacements. In 27 cases (20.9%) additional cardiac surgery was performed. Maximum follow-up was 5.5 years with a mean of 37.9 months. The cumulative follow-up was 407.25 patient-years. Overall hospital mortality was 1.6% (2 cases). There were 3 late deaths in this series (2.4%). The linearized incidence of late mortality was 0.49% per patient-year. The survival actuarial curve was 96% +/- 1.8. The incidence of thromboembolism was 1.22% per patient-year, and the actuarial thromboembolism-free rates was 93% +/- 2.7. Prosthetic endocarditis occurred in one patient. Three patients developed primary tissue failure of the Mitroflow valve in the mitral position. The linearized incidence of primary tissue failure was 0.73% per patient-year and the actuarial freedom from primary tissue failure was 95% +/- 3.2. A total of 4 patients underwent reoperation (0.49% per patient-year). In conclusion, the clinical performance of the Mitroflow pericardial heart valve at medium-term follow-up is satisfactory, however a significant number of early mitral primary tissue failures have already occurred.

Long-term evaluation of the Ionescu-Shiley pericardial xenograft bioprosthesis in the aortic position

From August 1977 through October 1984, 241 patients underwent aortic valve replacement with the Ionescu-Shiley pericardial valve. There were 130 males and 11 females in this series with an average age of 50.8 years (range 15 to 78 years). Isolated aortic valve replacement was performed in 121 patients (50.2%) and associated cardiac surgery in 120 (49.8%). Valve size was 21 mm or smaller in 107 cases (50.2%). Cumulative duration of follow-up was 1,260 patient-years with a mean follow-up of 5.16 years per patient. Five patients were lost to follow-up. Maximum follow-up was 10.5 years. There were 26 hospital deaths and 15 late deaths (1.19% per pt-yr). The expected 10.5 year actuarial survival rate is 82% +/- 2.9%. Twelve thromboembolic episodes occurred in seven patients--seven central and five peripheral events. The thromboembolic rate was 0.95% per patient-year--32% for patients with isolated aortic valve replacement and 0.63% for patients with concomitant surgery. Freedom from thromboembolic episodes at 10.5 years is 73% +/- 12%. Structural valve deterioration was found in 24 patients (1.9% per pt-yr) with an actuarial freedom from primary tissue failure of 77.5% +/- 5.4% at 10.5 years. Reoperation was required in 39 cases (3.09% per pt-yr)--primary tissue failure (n = 24), paravalvular leak (n = 7), infective endocarditis (n = 6), and valve thrombosis (n = 2).

Stability of mitral reconstructive surgery at 10-12 years for predominantly rheumatic valvular disease

All consecutive patients who underwent Duran flexible ring annuloplasty in 1975 and 1976 were reviewed until June 1987. Eighty-seven annuloplasties were performed in 85 patients. Aortic, tricuspid, or both surgeries were simultaneously performed in 44.8%. The hospital mortality was 2.3% (two of 85). Ten patients were lost to follow-up within 2 years after surgery, and there were three late deaths. Thromboembolic events were detected in 18 patients (seven peripheral and 11 central with one death); nine patients had partial recovery, and eight had full recovery. At the time of the thromboembolic event, eight patients were receiving anticoagulants; four, antiaggregants; one, both anticoagulants and antiaggregants; and five, none. Thirteen patients (13 of 73, 17.8%) required reoperation between 1 month and 11 years postoperatively. The valve was replaced in 11 patients, and two underwent a new flexible ring annuloplasty. The cause for reoperation was regurgitation in eight patients (10.9%), for whom the mean interval between operations was 20.6 months (range, 1 month-11 years). Stenosis was the cause for reoperation in five patients (6.8%), for whom the mean interval between operations was 87.8 months (range, 4-11 years). We conclude that reconstructive surgery after 10-12 years of follow-up for this group of predominantly rheumatic patients has an incidence of failure of approximately 18% attributable to incorrect surgery (11%) and restenosis (7%).

A head-to-tail tandem organization of hsp70 genes in Trypanosoma cruzi

We describe the isolation and characterization of the T. cruzi hsp 70 DNA coding region which was found to be formed by multigene copies organized in a tandem array in a head-to-tail manner. The restriction pattern of one of the repetition units within the largest clone obtained from the genomic library, clone Tc70.6, shows that the hsp70 coding region should be formed by at least seven identical copies of 2.5 kb. We have found, however, the presence of restriction polymorphisms (Pvu II) within these repeats. Subsequent analysis of the time course of nuclear DNA digestion has revealed that the copy number per haploid genome could be as greater as 10. The analysis of the DNA and amino acid sequence of a fragment (70%) of one of the repetition units has shown the existence of a high homology with all the hsp70 genes of other organisms. The protein sequence homology of the fragment analyzed is as high as 88% when compared with that of the T. brucei hsp70. On the other hand, there are significant restriction site variations between both. The T. cruzi hsp70 contains at the C-terminal end a tetrapeptide repeat of the structure (GMPG)9.

Activity of rhodium(III) complexes against Trypanosoma cruzi

In the present paper the antiprotozoan activity of several rhodium(III) complexes was studied by analysis of the [3H]-thymidine, [3H]-uridine and [3H]-leucine uptake occurring in epimastigotes of Trypanosoma cruzi in the presence of the drug as well as their effect on the viability and motility of infective forms. It has been found that the complexes do not interact with native DNA but that some of them inhibit both the precursor uptake and the viability of metacyclic forms. It seems that the mode of action on the epimastigotes should be different from that observed on metacyclic forms.

Long-term results of conservative repair of rheumatic aortic valve insufficiency

From July 1974 to January 1986, 50 patients underwent conservative repair for rheumatic aortic valvular disease at our institution. Eleven were male and 39 female, with an average age of 39.5 years (range 17-57). The aortic lesion was associated in all cases with a predominant mitral lesion. Twenty-five also had tricuspid disease which was surgically treated in 17. Twenty-six had aortic regurgitation and 24, a mixed lesion. The surgical techniques used were: (1) commissurotomy, (2) annuloplasty, (3) cusp free edge unfolding and (4) supra-aortic crest enhancement. Two patients had one cusp extended with pericardium. There were 3 hospital deaths (6%). Six patients were lost to follow-up at different periods. Maximum follow-up was 12.58 years with a mean of 7.78 years per patient. Twelve required reoperation with 3 deaths. Three reoperations were due to failure of the mitral bioprosthesis without reoperation on the aortic valve. Of the remaining 9 patients who had aortic and mitral dysfunction, 4 had severe aortic insufficiency. The actuarial freedom from reoperation at 13 years was 75% and the overall actuarial survival was 86%. It is concluded that these surgical techniques can be applied successfully in moderate rheumatic aortic valve disease accompanying a predominant mitral lesion. This is particularly relevant when a mitral reconstruction has been performed.

Antitrypanosomal action of cis-diamminedichloroplatinum (II) analogs

The present report deals with the alterations produced by cis-diamminedichloroplatinum (II) (DDP), and 2 of its analogs: cis-Pt(II)(tranylcypromine)2Cl2 and cis-Pt(II)(benzothiazole)2Cl2 in cultured epimastigote forms of Trypanosoma cruzi. Studies have been performed at the ultrastructural level and the inhibitory effect of these complexes on macromolecule synthesis, evaluated by 3H-thymidine, 3H-uridine, and 3H-leucine incorporation, has been investigated. DDP at concentrations of 50 and 100 micrograms/ml does not inhibit significantly the incorporation of radioactive precursors, but a clear decrease was observed with the 2 analogs. Eight hours of treatment at a concentration of 10 micrograms/ml rendered in all 3 cases an increase in autophagic vacuoles and lipids as well as an abnormal condensation of the nucleus chromatin.

Mode of action of intercalating drug, cis-Pt(II)(DDH)Cl2, cis-Pt(II)(DDH) (metafluorobenzoic)2, and cis-Pt(II)(DDH)(mucubromic)2, on Trypanosoma cruzi

The trypanocidal activity of three new compounds derived of the antineoplastic drug cis-diamminodichloroplatinum(II) (DDP) has been studied over epimastigote forms of Trypanosoma cruzi. The electron microscopy indicated that, in the treated animals, the nuclear chromatin is distributed in the nucleus in a lax form and that the number of lipidic vacuoles increases largely. This action is more significant when cis-Pt(II)1,2-diaminocyclohexane is used. In addition this compound causes a destabilization of the DNA double helix with a decrease of melting temperature. The three compounds inhibit the incorporation of leucine, uridine and thymidine, although the thymidine uptake is the most significantly affected.

Z-DNA in transcriptionally active chromosomes

Due to the striking correlation between the distribution of transcriptionally active subdivisions of the polytene chromosomes and Z-DNA, we have addressed the question of whether the Z-DNA configuration exists in native, transcriptionally active chromosomes of Drosophila hydei prepared without interference by procedures known to induce the B to Z conformation. Our experiments indicate that Z-DNA forms are present in a specific set of sites on the native chromosomes. They occur on interbands and other subdivisions of dispersed DNA, but there is no correlation between the amount of Z-DNA detected and DNA compaction. The results suggest, moreover, that Z-DNA forms are restricted to specific genes, because various subdivisions induced to transcription in puffs show different patterns of Z-DNA. We show, in addition, that removal of chromosomal proteins by proteinase K has a strong influence on the level of anti-Z-DNA reactivity.

Studies on the interaction between antitrypanosome cis-DDP analogs with DNA

The nature of the conformational changes produced in DNA by cis-DDP analogs has been studied by physiochemical techniques. The UV spectra showed that the DNA undergoes bathochromic shifts accompanied by hyperchromic effects in reaction with specific analogs (cis-Pt(DDH) (mucobromic)2, cis-Pt(tranilcypromine)2Cl2 and cis-Pt(DDH) Cl2), while a different series of analogs (cis-Pt(DDH) (metafluorobenzoic)2 and cis-Pt(pentamidine)Cl2) induce a significative decrease in the absorbance at 258 nm. Moreover one of these analogs (cis-Pt(pentamidine)Cl2) causes strong stabilization of the double helix to heat denaturation. The CD spectra indicate moreover that cis-Pt(pentamidine)Cl2 modifies the secondary structure of the DNA in a significant way with an increase of the positive band and a decrease of the ellipticity of the negative band. The antitrypanosome activity of cis-Pt(pentamidine)Cl2 is probably due to inhibition of the intracellular parasites division in parasitized cells.

Locations of Z-DNA in polytene chromosomes

In polytene chromosomes of Drosophila hydei and D. melanogaster, Z-DNA was identified in varying distribution after different conditions for fixation were used. When salivary glands were fixed and squashed in 50% acetic acid alone, Z-DNA was found in the less dense DNA regions, such as interbands, some puffs, and a few of the less dense bands. Prefixation that combined ethanol and acetic acid exposure led to prominent immunofluorescent staining of the bands, generally but not strictly correlating with the total DNA content. Separate exposure to ethanol and acetic acid did not cause this band to stain, but if residual ethanol was present after ethanol fixation, subsequent exposure to acid did cause it. Under the more selective acid fixation conditions, Z-DNA reactivity was seen in portions of certain ecdysone-inducible puffs in the induced but not in the resting state; in other inducible regions, the Z-DNA immunoreactivity was not changed on induction. Z-DNA was also identified in polytene chromosomes within isolated nuclei that had been frozen and fixed in ethanol without exposure to acid; this Z-DNA was present in regions of low DNA density.