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Biomedical subjects

C Alonso

Publications and source records attributed to C Alonso.

At least 307 records · Page 17Linked to original sources
PubMed1989

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.

Brain Neoplasms↗
PubMed1989

Post-remission therapy in acute myeloblastic leukemia. A randomized trial comparing early consolidation plus maintenance versus maintenance therapy alone.

During a 5-year period 203 previously untreated patients with acute myeloblastic leukemia entered an intensive induction chemotherapy regimen with daunorubicin, cytosine arabinoside, 6-thioguanine, vincristine and prednisone (DATOP). The complete remission rate was 64%. Patients in complete remission were randomly assigned to 3 courses of early consolidation with DATOP at lower dosage followed by maintenance chemotherapy, or to the same maintenance regimen in the absence of any consolidation courses. No significant differences were found between these options concerning disease-free survival (median 7.0 vs. 9.8 months; p greater than 0.10) or survival (median 15.8 vs. 19.4 months; p greater than 0.10). This study, in addition to the few previously reported randomized trials, suggests that early low-dose consolidation adds no benefit to maintenance chemotherapy in acute myeloblastic leukemia once complete remission has been achieved.

Adolescent↗
PubMed1989

Time-dependent rheological behaviour of blood flow at low shear in narrow horizontal tubes.

Magnitude and time-dependence of the effects of red cell aggregation and sedimentation on the rheology of human blood were studied during low shear (tau W 2.5 to 92 mPa) flow through horizontal tubes (ID 25 to 105 microns). Immediately following reduction of perfusion pressure to a low value the red cell concentration near the tube walls decreases as a result of red cell aggregation. This is associated with a transient increase of centerline velocity. Simultaneously, sedimentation begins to occur and eventually leads to the formation of a cell-free supernatant plasma layer. Time-course and extent of this sedimentation process are strongly affected by wall shear stress variation, particularly in the larger tubes. At the lower shear stresses, centerline velocity decreases (flow resistance increases) with time following the initial acceleration period, due to sedimentation of red cells. This is followed by a further increase of resistance caused by the elevation of hematocrit occurring because of the reduction of cell/plasma velocity ratio. The time dependence of blood rheological behaviour under these flow conditions is interpreted to reflect the net effect of the partially counteracting phenomena of sedimentation and red cell aggregation.

Blood Flow Velocity↗
PubMed1989

[Tobacco consumption in a group of physicians of the V Valparaiso Region (Chile)].

We surveyed 174 physicians from the Valparaiso area regarding smoking habits. 25% were smokers and 75% were not, among them 103 exsmokers (70%). A slightly higher, but not significant percentage of women smokers was observed. Compared to the general population in that area the percentage of physician smokers is significantly lower. The latter show a greater tolerance to smoking habit among their family and patients. Most doctors surveyed were not impressed by the anti-smoking campaigns of health authorities.

Adult↗
PubMed1989

Malignant B cell immunoblastic lymphoma expressing CD30 antigen in the terminal phase of a multiple myeloma.

An acute terminal phase of a Bence Jones kappa plasma cell myeloma developed 22 months after chemotherapy is presented. The patient's symptoms were fever, cytopenias, adenomegalies and hepatomegaly. A lymph node biopsy showed an immunoblastic polymorphic kappa B cell lymphoma, expressing CD30 antigen. After new polychemotherapy the patient died because of bleeding and infection. Autopsy revealed a decrease in the tumour with defective immunophenotype. The few reported cases have been reviewed with emphasis on clinical aspects, prognosis and morphology, The significance of CD30 positivity (activation marker) in a high-grade lymphoma is discussed.

Aged↗
PubMed1989

[The Ionescu-Shiley bioprosthesis in the aortic position. Medium to long-term evaluation].

From August 1977 through October 1984, 241 patients underwent aortic valve replacement with the Ionescu-Shiley prosthesis. The average age was 50.8 years (range 15 to 78). Aortic valve replacement was performed alone in 121 patients (50.2%) and with associated surgery in 120 (49.8%). Cumulative duration of follow-up was 1,260.08 patient-years, with a mean follow-up of 5.32 years per patient. Five patients were lost to follow-up. There were 26 hospital deaths and 15 late deaths (1.19% per patient-year). The expected 10.5 year actuarial survival rate was 82 +/- 2.9%. Twelve thromboembolic episodes occurred in 7 patients (7 central and 5 peripheral). The linearized thromboembolic rate was 0.95% per patient-year: 0.32% for patients with isolated aortic valve replacement and 0.63% for patients with concomitant surgery. Freedom from thromboembolic events at 10.5 years was 78 +/- 12%. Structural valve failure was found in 24 patients (1.9% per patient-year) with an actuarial rate of freedom for primary tissue failure of 72.6 +/- 6.1% at 10.5 years. Reoperation was required in 39 cases (3.09% per patient-year) due to primary tissue failure (n:24), paravalvular leak (n:7), infective endocarditis (n:6) and valve thrombosis (n:2). In conclusion, this pericardial bioprosthesis has demonstrated an adequate performance at mid and long-term follow-up, but somehow less satisfactory than previously reported.

Adolescent↗
PubMed1989

[The Mitroflow bioprosthesis. Results after 6 years].

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 years (range 26 to 74 years). Eighty-nine patients underwent isolated aortic valve replacement, 27 isolated mitral valve replacement, three isolated tricuspid valve replacement and ten mitral-aortic valve replacement. In 20.9% additional cardiac surgery was performed. Maximum follow-up was 6 years with a mean of 43.9 months. The cumulative follow-up was 491 patients/year. 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 rate was 93% +/- 2.7. 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 primary tissue failures have already occurred in the mitral position.

Adult↗
PubMed1989

[Granulocytic sarcoma of the base of the skull in chronic myeloid leukemia].

A 54 years old patient with Ph' negative chronic granulocytic leukaemia is reported, who presented rapidly progressive multiple cranial nerve palsies. A cerebral CT scan showed an invasive tumoral disease on the base of skull. Histologic examination of this mass was diagnostic for granulocytic sarcoma, which was the presentation form of an extramedullary blastic crisis. The general characteristics of granulocytic sarcoma are commented, special attention being paid to its appearance in the course of chronic granulocytic leukaemia.

Blast Crisis↗
PubMed1988

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.

Amino Acid Sequence↗
PubMed1988

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.

Adolescent↗
PubMed1988

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.

Adult↗
PubMed1988

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).

Adolescent↗
PubMed1988

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.

Animals↗
PubMed1988

A randomized trial comparing chlorambucil plus prednisone vs cyclophosphamide, melphalan, and prednisone in the treatment of chronic lymphocytic leukemia stages B and C.

Ninety-six previously untreated patients (67 males/29 females; mean age: 63 years; range: 46-84) with CLL in stage B (62 cases) or C (34 cases) were randomized to be treated with either chlorambucil (0.4 mg/kg orally days 5 and 6) plus prednisone (60 mg/m2 orally days 1 to 4) (CL + PDN) every 2 weeks or cyclophosphamide (160 mg/m2 orally days 1 to 4), melphalan (6 mg/m2 orally days 1 to 4), and prednisone (60 mg/m2 orally days 1 to 4) (CMP) every 3 weeks for 10 months. Forty-eight patients were treated with CLR + PDN, and the remaining 48 with CMP. The following types of response were considered: complete response (CR): total disappearance of symptoms and signs related to the disease. Partial response (PR): shift of the disease to a less advanced stage. Stable disease (SD) no change in the stage after treatment. Progressive disease (PD): progression of the disease to a more advanced stage. Thirty-six (75%) responses (27% CR) with CLR + PDN and 26 (54.5%, 12.5% CR) with CMP were observed (p = 0.054). Although more responses were achieved in stage B (69%, 24% CR) than in stage C (54%, 12% CR) this difference did not achieve statistical significance. Survival was statistically not different for those patients treated with LCR + PDN as compared to those receiving CMP.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

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%).

Adolescent↗
PubMed1987

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.

Animals↗