Acute myocardial infarction in the Brazilian State of São Paulo. In-hospital deaths from 1979 to 1996 and hospital fatality from 1984 to 1998 in the public health system.

OBJECTIVE: To determine the following parameters in the Brazilian State of São Paulo: 1) the percentage of deaths due to acute myocardial infarction (AMI) occurring in hospitals; 2) the percentage of deaths due to AMI occurring in public health system hospitals as compared with all in-hospital deaths due to AMI between 1979 and 1996; 3) the fatality due to AMI in public health system hospitals from 1984 to 1998. METHODS: Data were available on the Datasus Web site (the health information agency of the Brazilian Department of Health) that provided the following: a) number of deaths resulting from AMI in hospitals; b) number of deaths resulting from AMI in public health system hospitals; c) number of hospital admissions due to AMI in public health system hospitals. RESULTS: The percentage of in-hospital deaths due to AMI increased from 54.9 in 1979 to 68.6 in 1996. The percentage contribution of the public health system to total number of deaths due to AMI occurring in hospitals decreased from 22.9 in 1984 to 13.7 in 1996; fatality due to AMI occurring in public health system hospitals had an irregular evolution from 1984 to 1992 and showed a slight trend for increased frequency from 1993 to 1998. CONCLUSION: The percentage of in-hospital deaths due to AMI has been increasing. Deaths resulting from AMI in public health system hospitals have decreased when compared with the total number of deaths due to AMI in all hospitals. Fatality due to AMI in public health system hospitals did not decrease from 1992 to 1998.

Response of an experimental mammary carcinoma to fractionated X-irradiation with misonidazole and microwave hyperthermia.

X/Gf mice bearing the MT2 mammary adenocarcinoma were subjected to 4,000 rad of X rays given either as a single dose, or five daily fractions of 800 rad. Additional experimental groups were treated with either short term localized microwave hyperthermia (LMH) (42.5 degrees C for 25 min.), or the hypoxic cell radiosensitizer misonidazole (MISO) (0.67 mg/g bw), or both hyperthermia plus MISO with X rays. The combined use of MISO plus 42.5 degrees C with X rays was superior to the other treatment regimens as assessed by tumor regrowth delay and mean survival time. However, for the five fraction schedule, the addition of MISO plus hyperthermia was not as effective as observed for the single dose treatment. This may be attributed to reoxygenation of the hypoxic tumor cells between treatment fractions. MISO retention in tumor tissue under ambient and hyperthermic conditions was studied. The application of heat locally to the tumors caused a significant increase in MISO tumor concentration. However, after four X ray fractions the influence on MISO concentration by hyperthermia in the tumors could not be demonstrated. This may be related to the stromal damage by X rays in the tumor tissue that was observed histologically.

Thermally-enhanced tumor regression in mice treated with melphalan.

Mice were implanted subcutaneously with one of three types of tumor, each isogeneic to the respective host. These were two mammary adenocarcinomas designated DBAH and MT2, and a spindle cell sarcoma designated TEC. Tumor-bearing mice were treated with melphalan alone, locally-applied microwave hyperthermia alone (42-43 degrees C) or with a combination of these two modalities. Following treatment, tumor growth and regression, and survival of host were recorded. Only mice bearing the DBAH tumor were cured by either modality alone. The MT2 and TEC tumors responded only slightly to melphalan treatment alone. Approximately half of the TEC tumors responded to prolonged treatment by hyperthermia alone, yielding total regressions; the MT2 tumor proved to be resistant to this modality. Doses of hyperthermia which had no effect on tumor growth when applied alone were able to induce a thermal potentiation of melphalan. All 3 tumor types were cured by this combined treatment, although different doses of hyperthermia were required for each tumor type.

Combined effects of misonidazole, microwave hyperthermia, and X-rays on the in vivo sister chromatid exchanges and chromosomal abnormalities of the dbrB tumor and on the survival of its host.

A rapidly proliferating mammary adenocarcinoma designated dbrB growing s.c. in isogeneic female DBA/1J mice in their 278th passage of transfer constituted the experimental host tumor system. A 5-bromodeoxyuridine pellet (2.5 mg/g body weight) was used for sister chromatid exchange analysis of the 0.5-cu cm dbrB tumor. Experiments were performed on Group I, untreated tumor-bearing mice, and Group II, tumor-bearing mice treated with triple agents: misonidazole (1 mg/g body weight); 42.5 degrees microwave hyperthermia for 10 min; and X-rays administered singly or in combination at about 4 hr following the implantation of a 5-bromodeoxyuridine pellet. The X-ray treatments consisted of 400, 1000, 1500, and 2000 rads, respectively. X-rays and hyperthermia were delivered to the tumors directly, while the rest of the mouse body was lead shielded. Survival of the untreated tumor-bearing control mice in Group I was 12 +/- 3 (S.D.) days, whereas the mice in Group II whose tumors were treated with misonidazole, hyperthermia, and 2000 rads of X-rays survived 27 +/- 3 days. 5-bromodeoxyuridine per se had no effect on the survival of the experimental mice. Only a dose of 400 rads administered to the dbrB tumors permitted detailed evaluation of chromosomal analyses, whereas the larger doses of radiation caused cellular destruction. Simultaneous treatment with triple agents resulted in sister chromatid exchanges of 33.78 +/- 0.39/cell as compared with sister chromatid exchanges of 14.74 +/- 0.39/cell of untreated control tumors. This mode of treatment also induced various types of chromosomal abnormalities in the tumor cells.

Sister chromatid exchanges and chromosome aberrations induced by radiosensitizing agents in bone marrow cells of treated tumor-bearing mice.

The frequency of sister chromatid exchanges (SCE) in vivo and chromosome aberrations and/or alterations were analyzed from the bone marrow cells of the treated dbrB tumor-bearing DBA/1J inbred mouse host. The results were compared with analogous data obtained from the bone marrow cells of untreated tumor-bearing mice for evaluation of the "indirect," i.e., somatic stress, effect on the normal host cells following triple-agent therapy intended for a mammary adenocarcinoma. Misonidazole (MIS), which is a known radiosensitizing drug, microwave hyperthermia (delta), and X-radiation (X) were used as therapeutic agents. Significant (P less than 0.05) numbers of SCE were induced in the bone marrow cells of the mice whose tumors received these triple-agent treatments (MIS + delta + X) simultaneously as compared with values of SCE per cell noted in bone marrow cells of untreated tumor-bearing control mice. The highest number of chromosome aberrations and alterations, including an increase in heteroploidy, was also noticed in the bone marrow cells of the mice whose tumors were treated simultaneously with MIS + delta + X. The triple-agent therapy on dbrB tumor also resulted in an unusually high polyploid metaphase plate in the bone marrow cell consisting of 320 chromosomes, indicating that this mode of therapy may act directly on the genetic material of the tumor-bearing host cells, inducing cytogenetic abnormalities as a side effect.

Cell kinetics, cell structure, and radiotherapy.

This study was carried out on five types of experimental tumors maintained by serial subcutaneous transplants in isogeneic mouse hosts. These tumors involved three mammary carcinomas (dbrB, DBAH, MT2), a spindle-cell sarcoma (TEC) and a lymphoblastic type of lymphoma (DBA/3). Growth curves of these tumors are presented. Computed percent labeled mitoses curves for the five types of tumors, the derived cell cycle parameters (TG1, TG2, TS, Tc), and the volume-doubling time (VDT) in days are also presented. The histologic and morphologic appearance of each type of tumor is seen by light microscopy, and the ultrastructural morphology of each type of tumor is seen in electron micrographs. The variation in the kinetic parameters and the autoradiographic exposure time needed to obtain comparable labeling intensity for the five types of tumors is interpreted on the basis of the ultrastructural integrity of the cytoplasmic components of the individual tumor type. The response of these five tumor types to radiotherapy was investigated. The therapy consisted of administering combined treatments of three agents: X-rays, the radiosensitizing drug, misonidazole, and microwave hyperthermia. This treatment resulted in an enhancement factor of 3.9, compared with that of X-rays alone. Total tumor regressions were obtained with microwave hyperthermia alone. The required time of exposure to hyperthermic treatments differed, depending on the response of each type of tumor.

Adriamycin damage: in vivo repair by lymphoma cells.

The in vivo repair of ADR-induced cell damage was investigated in the DBA3 transplantable mouse lymphoma. After a single injection of 5 or 15 mg ADR/kg body weight into DBA/2J mice, the survival fraction of clonogens showed a 2.2- to 4.4-fold decrease at 12 or 18 hours post injection and returned to pretreatment levels within 6 hours. These changes were accompanied by the appearance and disappearance of DNA crosslinks and breaks. Because cell division and/or cell loss could not explain the return of clonogens to pretreatment level, the results strongly suggest repair of ADR damage in tumor cells in situ. Such an efficient repair mechanism, responding to a high toxic dose of ADR, constitutes a therapeutically unfavorable event that may contribute to drug resistance.

Sister chromatid exchanges in vivo in mouse mammary adenocarcinoma.

The proliferation and genetic characteristics of a mouse mammary adenocarcinoma designated dbrB are described. This tumor was maintained as subcutaneous serial transplants in syngeneic inbred mice of the DBA/1J strain. Quantitative in vivo sister chromatid exchange(s) (SCE) were determined in the tumor cells and in the bone marrow cells of the host strain. Over a twofold increase in SCE, frequency was noted in the dbrB tumor cells compared to the bone marrow cells. The high frequency of SCE in the dbrB tumor was assumed to be caused by the high degree of malignancy of this tumor. Such information indicating genetic stress may serve for evaluation of the degree of malignancy in neoplasms.

Spleen-shape as a genetic marker in X/Gf mice.

This study revealed that the triangular shaped spleen of X/Gf mice constitutes a genetically dominant characteristic over normal spleen shape of C3H mice. The agouti coat color of C3H mice is dominant over the white color of the X/Gf strain. The mode of transmission of triangular shape of the spleen in X/Gf mice, as well as their white coat color indicates Mendelian autosomal inheritance involving two independent genes. Although the pedigree lends support to this inference, we are aware that the small number of F2 offspring available for this study limits the conclusions to be drawn from the segregation ratio and statistical evaluation.

Protein-associated DNA breaks and DNA-protein cross-links caused by DNA nonbinding derivatives of adriamycin in L1210 cells.

The effects of Adriamycin derivatives on L1210 mouse leukemia cells were studied with the DNA alkaline elution assay. The exposure of exponentially growing cells to approximately equitoxic concentrations of N-trifluoroacetyladriamycin-14-valerate (13.8 microM) and its metabolites, N-trifluoroacetyladriamycin (9.0 microM) and N-trifluoroacetyladriamycinol (43.7 microM), for 1 hr in vitro resulted in a high frequency of protein-associated DNA breaks and DNA-protein cross-links. These effects were comparable to those observed with Adriamycin (2.8 microM) and with adriamycinol (26.9 microM). In contrast to Adriamycin and its metabolite adriamycinol, N-trifluoroacetyladriamycin-14-valerate and its two major metabolites do not bind to DNA. Despite the absence of this direct interaction, N-trifluoroacetyladriamycin-14-valerate and its metabolites produce alterations in DNA comparable with the effects of intercalating agents. No evidence for conversion of N-trifluoroacetyladriamycin-14-valerate to Adriamycin or adriamycinol was found in L1210 cells. The similar effects on DNA macromolecules, observed between intercalating and non-DNA-binding anthracyclines, are consistent with the concept that mechanisms other than direct interaction with DNA play a role in the toxic effects of these compounds.

Deficiency of nuclease activity in ribosomes of three tumor types.

Polysomes isolated from 3 types of neoplasms, mouse mammary adenocarcinoma designated DBAH, morris rat hepatoma 7777, and mouse chloroleukemia, do not undergo fast degradation upon incubation at 37 degrees C, unlike polysomes isolated from corresponding isogenic, normal tissues. Further,. 1M KCl extract of ribosomes from normal cells, in contrast to their neoplastic counterparts, stimulate degradation of poly(U). The nuclease activity in ribosomal preparations from neoplastic cells is not increased in the presence of p-chloromercuribenzoate, a blocking agent of RNAase inhibitor. This suggests that ribosomal preparations from tumor cells are free of nucleases rather than just being masked by an inhibitor. Ribosomes from neoplastic cells stimulate protein synthesis in vitro in the presence of endogenous or exogenous mRNA to a much higher degree than similar preparations from normal tissues. This event is in agreement with the deficiency of nuclease in polysomes from neoplastic cells.

Cell kinetics of irradiated experimental tumors: cell transition from the non-proliferating to the proliferating pool.

Parenchymal tumor cells of murine mammary carcinomas can be divided into two pools, using nucleoli as morphological 'markers'. Cells with dense nucleoli traverse the cell cycle and divide, thus constituting the proliferating pool. Cells with trabeculate or ring-shaped nucleoli either proceed slowly through G1 phase or are arrested in it. The role of these non-proliferating, G1 phase-confined cells in tumor regeneration was studied in vivo after a subcurative dose of X-irradiation in two transplantable tumor lines. Tumor-bearing mice were continuously injected with methyl[3H]thymidine before and after irradiation. Finally, the labeling was discontinued, mice injected with vincristine sulfate and cells arrested in metaphase were accumulated over a 10-hr period. Two clearly delineated groups of vincristine-arrested mitoses emerged in autoradiograms prepared from tumor tissue at the time of starting tumor regrowth: one group with the silver-grain counts corresponding to the background level, the other with heavily labeled mitoses. As the only source of unlabeled mitoses was unlabeled G1 phase-confined cells persisting in the tumor, this observation indicated cell transition from the non-proliferating to the proliferating pool, which took place in the initial phase of the tumor regrowth. Unlabeled progenitors have apoparently remained in G1 phase for at least 5-12 days after irradiation.

Enhancement of radioresponse of a mouse mammary carcinoma to combined treatments with hyperthermia and radiosensitizer misonidazole.

The regrowth delay of a transplanted syngeneic mouse mammary carcinoma designated MT2 was used to estimate the effects of three-fold combination treatments: X-irradiation; hyperthermia and radiosensitizer; and misonidazole (Ro-07-0582). The experiment entailed five groups of experimental mice: untreated control; X-rays alone; X-rays plus hyperthermia (42--43 degrees); X-rays plus misonidazole; and X-rays plus hyperthermia plus misonidazole. X-Ray treatments consisted of 4000 rads administered locally to the tumors in two equal fractions at a 48-hr interval. Misonidazole (0.67 mg per g body weight) was injected i.p. 30 min before exposure to X-irradiation. Hyperthermia was administered 10 min prior to and for 17 min during irradiation. The regrowth delay factor of 3.9 was obtained by administering combined treatments of the three agents (X-rays plus hyperthermia plus misonidazole). The enhancing effect on a syngeneic mouse mammary adenocarcinoma by the modality of treatment herein described lends support to the usefulness of combining X-rays with other agents in the treatment of neoplasms.

Identification and kinetics of G1 phase-confined cells in experimental mammary carcinomas.

Three lines of mouse mammary carcinoma growing in isogenic hosts and differing in degree of histological differentiation and rates of proliferation were used to study parenchymal cells with various types of nucleoli. The relative number of cells possessing trabeculate or ring-shaped nucleoli or nucleolar fragments was closely related to the growth rate and degree of differentiation of tumor lines tested. All three subpopulations increased with increasing age and with decelerated tumor growth. In some cells in late telophase, either trabeculate or ring-shaped nucleoli could be distinguished in mitotic poles. This demonstrated that cells with these nucleoli are detected at the beginning of G1 phase. Even low levels of DNA synthesis, which would indicate that some cells with trabeculate or ring-shaped nucleoli or possessing nucleolar fragments were in S phase, could not be demonstrated. Microfluorometric measurements have indicated that cells with trabeculate and ring-shaped nucleoli have a DNA content close to 2c, whereas cells with dense nucleoli have a DNA content corresponding to either 2c, 2 to 4c, 4c, or greater than 4c. On the basis of these observations, it is concluded that cells with trabeculate and ring-shaped nucleoli and cells with nucleolar fragments either proceed slowly through G1 or are arrested in this phase. Cells with trabeculate nucleoli were replaced steadily, having a transit time of no longer than 84 hr. These cells constituted a "fast" component of cell renewal of G1-confined cells. A "slow" component, cells bearing ring-shaped nucleoli or nucleolar fragments, were replaced after a lag of 24 to 48 hr. with residency time for some of these cells being in excess of 84 hr.

Induction of type B virions to bud into cytoplasmic vacuoles in a mammary tumor of an X-ray- and urethan-treated X/Gf mouse.

Electron microscopic studies of thin sections of a mammary carcinoma that developed in a female mouse of the syngeneic X/Gf low-cancer strain after treatments with X-rays (3 X 100 rads weekly) followed by 8 weekly i.p. injections of urethan (1 mg/g body weight) revealed extensive budding of B particles into cytoplasmic vacuoles and numerous characteristic B virions in the vacuolar lumens. Simultaneous budding of B particles into cytoplasmic vacuoles and budding of B particles at plasma membranes of the same cancer cell were also noted (figs. 2 to 6).

Transfer RNA species in tumors of different growth rates.

Tyrosyl-, histidyl-, lysyl-, and phenylalanyl-tRNA's from 3 tumors (DBAH, DBAH, and DBA), differing in growth rates and from host mammary glands and liver, were compared by means of methylated albumin kieselguhr (MAK) column and by reverse-phase-5 chromatography. The elution profiles of lysyl-tRNA's from DBAH and DBA, phenylalanyl Trna's from DBAH and DBAH, and histidyl-tRNA's from DBA3 tumors exhibited extra isoaccepting species, compared with host liver and mammary glands. The distribution of acylatable tyrosyl-tRNA's in DBA3 and DBAH, phenylalanyl-tRNA's in DBAH and DBAH2, and histid-l-tRNA's in DBA3 is higher than that in liver, whereas no appreciable differences were observed in the lysyl-tRNA contents of the tumors and liver. The chromatographic alternations appeared to be a property of the tumor tRNA's and not due to differences in aminoacyl-tRNA synthetases or due to the aggregation of tRNA's. The structural and functional significance of these findings are discussed.

Cell kinetics of irradiated experimental tumors: relationship between the proliferating and the nonproliferating pool.

The role of nonproliferating cells in tumor regeneration has been studied after subcurative doses of low L.E.T. irradiation. Radiation was applied in a single dose at three different levels; 0-47, 0-94 and 1-88 krad. Studies included estimation of the absolute number of cells per tumor, differential cell counts, and autoradiographic determination of kinetic variables, employing transplantable mouse mammary adenocarcinoma DBAH. Quantitative changes of morphologically defined proliferating and nonproliferating cell pools were followed at different time intervals after irradiation. Irradiation resulted in reduction of the number of cells in both pools, with apparent sparing of nonproliferating cells. The regenerative period started with a gradual increase in the number of cells in the proliferating pool, whereas the number of cells in the nonproliferating pool continued to fall in tumors irradiated with 0-94 and 1-88 krad. In the late phase of tumor regrowth, the increasing number of cells in the non proliferating pool corresponded to its replenishment by cell transition from the proliferating pool. In an effort to clarify whether cell transition from the nonproliferating to the proliferating pool may take place during the regrowth of radiation perturbed tumors, cell loss rates from both pools were estimated using experimental data. In addition to cell loses from the tumor as a whole, the 'net loss rate' of the nonproliferating pool reflects the rate of cell transition from the nonproliferating to the proliferating pool, minus the rate of transition in the opposite direction. A similar definition applies to cell loss rates from the proliferating pool. The results showed: (1) high losses in both pools, with excess losses in the proliferating during the early phase after irradiation; (2) in the early stage of regrowth after irradiation, the cell net loss rate f-or the nonproliferating pool increased, in contrast to the behavior of cell loss rate for the proliferating pool and the average cell loss rate for the tumor as a whole; (3) in the late stage of regrowth a decrease in net loss rate for the nonproliferating pool reflects the excess production of nonproliferating cells over control tumors. These results suggest that cell transition from the nonproliferating to the proliferating pool takes place at the beginning of tumor regrowth after subcurative single-dose irradiation.