Intermittent intensive combination chemotherapy with cisplatin, doxorubicin, and cyclophosphamide (cyclic PAC chemotherapy) for ovarian cancer

Despite high primary response rates with cisplatin-based combination chemotherapy, the overall survival rate for advanced ovarian cancer remains unsatisfactory. This prompted us to design a new systematic approach using a combination chemotherapy consisting of cisplatin, doxorubicin, and cyclophosphamide (PAC), namely, cyclic PAC chemotherapy. This is a 3-step chemotherapy with 3 courses of the PAC regimen in each step. It was administered for 18 months to patients with clinical Stage Ic-IV ovarian cancer, after cytoreductive surgery. In the present study, the cyclic PAC, brief PAC, and FAM (5-Fu, an alkylating agent, and mitomycin C) groups included 27 cases, 34 cases, and 38 cases, respectively. Treatment of Stage Ic-IV disease by cyclic PAC improved the outcome (57% estimated 5-year survival rate) compared to brief-PAC and FAM (20% and 32%, respectively). The outcome for patients with Stage III or IV ovarian cancer was also superior for the cyclic-PAC group compared to the brief-PAC and FAM groups (cyclic-PAC 44%, brief-PAC 9%, and FAM 0% estimated 5-year survival rates). Cyclic PAC chemotherapy was thus found to be capable of dramatically improving the long-term survival rate of ovarian cancer patients.

Neuroendocrine carcinoma of the uterus

Neuroendocrine carcinomas of the cervix and endometrium were reviewed. They have been variously designated as carcinoid, argyrophil cell carcinoma, apudoma, small cell carcinoma, oat cell carcinoma, endocrine carcinoma, and neuroendocrine carcinoma, the last-mentioned term being preferred in this chapter. Adenocarcinomas with neuroendocrine cells are occasionally encountered in the cervix and endometrium. It is generally questioned whether they should be included in the spectrum of neuroendocrine carcinomas, although differential diagnosis between some such tumors of the gastrointestinal tract and neuroendocrine carcinoma is reported to be difficult. Since the majority of neuroendocrine carcinomas of the cervix are highly aggressive, it is important to establish the neuroendocrine nature in the cervical carcinomas. In addition to the characteristic histologic features and argyrophil stainability, immunohistochemical demonstration of several neuroendocrine markers may be helpful in diagnosing neuroendocrine carcinoma of the cervix. Ultrastructural demonstration of neurosecretory granules is almost decisive in establishing the tumor's neuroendocrine nature, but it is not applicable in all cases. Neuroendocrine carcinomas of the cervix have been treated by surgery, radiation therapy, and chemotherapy, but optimal treatment methods have not yet been established because of the rarity of the tumor. Finally, we have described a typical neuroendocrine carcinoma of the cervix and reported some data regarding its experimental study.

An early activation antigen of murine T cells recognized by monoclonal natural autoantibody NTA204 and the expression on T cells from aged NZB x NZW F1 mice with overt autoimmune disease

A monoclonal natural thymocytotoxic autoantibody NTA204 established from an autoimmune-prone NZB mouse reacted with the majority of thymocytes, all peripheral B cells, granulocytes and bone marrow myeloid cells, but not with peripheral resting T cells of normal mice. In aged NZB/W F1 mice with overt autoimmune disease, the population of NTA204+ CD4+ CD25- T cells was remarkably increased. The NTA204 antigen could be induced on splenic T cells from normal healthy mice as early as 3 hr after the initiation of culture with stimulant Con A, and was expressed on the vast majority in the 48-hr culture. The expression preceded that of other T cell activation antigens tested, CD25 and CD45R. Cell cycle analysis suggested that NTA204 is expressed at an early phase of G1A. T cells, particularly CD8+ T cells, in the allogeneic mixed lymphocyte culture (MLC) could be divided into two populations, NTA204+ and NTA204-. By immunohistochemical analysis, 30% of NTA204+ CD8+, but few NT204- CD8+ T cells were intensely positive for large cytoplasmic granules of perforin, an important cytolytic mediator of cytotoxic T cells. Thus the increased population of NTA204+ T cells in aged NZB/W F1 mice appear to be activated T cells and might be at least partly involved in the pathogenesis of disease in these mice. Immunoblotting analysis of Con A-activated splenic T cells showed that NTA204 molecules have a molecular mass of 49 Kd.

[Detection of HPV DNA in the uterine cervical lesions by polymerase chain reaction and in situ hybridization]

Human papillomavirus (HPV) is found in close association with carcinogenesis of the uterine cervix. We applied a new in vitro gene amplification technology, the polymerase chain reaction (PCR) to detect HPV 16 and 18 in cervical exfoliated cells. HPV infections were detected in 5 (16%) of 31 women with no pathological lesions of the uterine cervix (normal), 16 (24%) of 67 with cervical intraepithelial neoplasia (CIN) and 6 (38%) of 16 with invasive cervical cancer. Moreover, 10% formalin-fixed and paraffin-embedded tissue sections were prepared from the uterine cervix of these 27 women with PCR-proven HPV infection and were examined for the histological localization of HPV-DNA by in situ hybridization with biotin-labeled DNA probes of HPV types 6/11, 16/18 and 31/33/35. HPV-DNA type 16/18 was detected in 3 of 5 normal women, 2 of 4 CINs I, 2 of 3 CINs II, 6 of 9 CINs III and 6 of 6 invasive cervical cancers. HPV-DNA type 6/11 was detected in 6 of 6 condylomas. Viral DNA sequence was detected in the superficial cells of CIN I and II, and it was distributed through entire thickness layer of undifferentiated cells derived from CIN III and squamous cell carcinoma. In addition, the staining intensity became weak as the lesion progressed. These differences between lesions might be due to the difference in the viral form in the nuclei, ie whether an episomal or integrated form. Thus, an in situ hybridization technique with a biotin-labeled DNA probe as well as the PCR method is useful for the detection of HPV in clinical samples.

Effect of cyclic guanosine monophosphate on hypoxic and angiotensin-II-induced pulmonary vasoconstriction

We examined, in isolated blood perfused rat lungs, the effect of the cell permeable 8-bromo derivative of cGMP on pulmonary vasoconstriction induced by either alveolar hypoxia or angiotensin II. 8-Bromo cGMP dose-dependently reduced both hypoxia-(IC50 = 2.2 X 10(-5) M) and angiotensin-II-induced pulmonary vasoconstriction (IC50 = 5.0 X 10(-5) M). This effect of 8-bromo cGMP on pulmonary vasoconstriction was not affected by cyclooxygenase blockade. M & B 22948 (0.1 mM), an inhibitor of cGMP-phosphodiesterase, reduced synergistically with 8-bromo cGMP the hypoxia or angiotensin-II-induced vasoconstriction. The cGMP-phosphodiesterase inhibitor M & B 22948, by itself, selectively reduced hypoxia-induced vasoconstriction, suggesting a modulating effect of endogenous cGMP during hypoxic vasoconstriction.

[Intermittent administration of the combination chemotherapy with cis-platin, adriamycin and cyclophosphamide (cyclic-PAC chemotherapy) for the ovarian cancers]

Despite cis-platin-based combination chemotherapy with initially high response rates in advanced ovarian cancer, the overall survival rate remains unsatisfactory. This prompted us to design a new systematic approach using a combination chemotherapy consisting of cis-platin, adriamycin and cyclophosphamide (PAC), namely cyclic-PAC chemotherapy: Three-step chemotherapies consisting of 3 courses of the PAC regimen in each step were administered for 18 months to patients with Stage Ic-IV, after cytoreductive surgery and chemotherapy. In the present study, the survival rate with the cyclic-PAC chemotherapy was compared to that with short course-PAC and FAM (5-Fu, Alkylating agent and Mitomycin C) chemotherapies. The cyclic-PAC, PAC and FAM groups included 24 cases, 31 cases and 30 cases, respectively. Treatment of Stage Ic-IV diseases by cyclic-PAC improved the outcome (66% 3-year survival rate) compared to PAC and FAM groups (PAC 35% and FAM 30% 3-year survival rates), while no difference was observed between PAC and FAM. The outcome for patients with Stage III. IV was also superior for the cyclic-PAC group compared to the PAC and FAM groups (cyclic-PAC 54%, PAC 18% and FAM 13% 3-year survival rates). Cyclic-PAC chemotherapy is capable of dramatically improving the long-term survival rate of ovarian cancer patients.

Embryonal carcinoma of the ovary: a six-year survival

We report a case of embryonal carcinoma, stage II, arising in the right ovary of an 18-year-old woman. The elevated serum levels of alpha-fetoprotein (AFP) and urinary human chorionic gonadotropin (hCG) rapidly normalized after conservative surgery followed by combination chemotherapy. The tumor was composed of large primitive cells and some multinucleated giant cells. AFP and hCG were demonstrated immunohistochemically in each type of cells. She has been disease-free for 6 years.

Pulmonary circulation during exercise in rats

Pulmonary arterial pressure of treadmill-running rats became significantly higher than the sedentary control level, while systemic arterial pressure did not rise. The rise of pulmonary arterial pressure seemed to be accompanied with the increase of cardiac output.

Dexamethasone in the treatment of acute mountain sickness

Cerebral edema occurs in fatal cases of acute mountain sickness. Dexamethasone, commonly used to treat cerebral edema due to other causes, also reduces the symptoms of acute mountain sickness when given prophylactically. However, the efficacy of dexamethasone in the treatment of established acute mountain sickness remains uncertain. To investigate this question, we exposed six men in a hypobaric chamber to a simulated altitude of 3700 m (barometric pressure, 64 kPa [481 mm Hg]) for 48 hours on two occasions. Acute mountain sickness was diagnosed with use of a symptoms questionnaire, and dexamethasone (4 mg every six hours) or placebo was then given in a randomized, double-blind, crossover fashion. Dexamethasone reduced the symptoms of acute mountain sickness by 63 percent (P less than 0.05), whereas placebo had a minimal effect (reduction by 23 percent; P not significant). In spite of this response, one subject had mild cerebral edema on brain CT after both placebo and dexamethasone. Dexamethasone had no effect on fluid shifts, oxygenation, sleep apnea, urinary catecholamine levels, the appearance of chest radiographs or perfusion scans, serum electrolyte levels, hematologic profiles, or the results of psychometric tests. Dexamethasone treatment was complicated by mild hyperglycemia in all subjects (mean [+/- SE] glucose level, 7.3 +/- 1.3 mmol per liter [132 +/- 23 mg per deciliter]). We conclude that dexamethasone effectively reduces the symptoms of acute mountain sickness. However, it did not improve objective physiologic abnormalities related to exposure to high altitudes. We therefore recommend that dexamethasone be used only when descent is impossible, or to facilitate cooperation in evacuation efforts.

Two distinct monoclonal natural thymocytotoxic autoantibodies from New Zealand black mouse

Autoimmune-prone NZB and NZB x NZW F1 mice have a large amount of autoantibodies cytotoxic for thymocytes (natural thymocytotoxic autoantibodies, NTA). We established two distinct monoclonal NTAs (NTA260 and NTA204) from a NZB mouse that react with the majority, but not all of these thymocytes. Flow cytometry analysis showed that NTA260 is positive on subpopulations of peripheral T cells from young mice, in which approximately 65% of CD4+ and 85% of CD8+ T cells were NTA260+. NTA260 also reacted with brain tissues of mice and rats, including Purkinje cells in the cerebellum. Western blot analysis showed that the molecular weight of NTA260 antigen was 55 kDa. In contrast to NTA260, NTA204 reacted with peripheral B cells but not with peripheral T cells in mice. NTA204 also reacted with peripheral blood granulocytes and bone marrow myeloid cells from both mice and rats. An immunofluorescence inhibition assay revealed the presence of autoantibodies with specificities of each NTA260 and NTA204 in the sera from NZB mice. As a selective decline in the subset of NTA260+ T cells but not NTA204+ B cells was observed with aging of NZB and NZB x NZW F1 hybrid mice, NTA260 is at least partly related to the observed immunological abnormalities of T cells in these autoimmune-prone New Zealand mice.

An immunohistochemical study of colon-ovarian tumor antigen and colon-specific antigen in gynecologic tumors

The distribution of colon--ovarian tumor antigen (COTA) and colon-specific antigen (CSA) was studied immunohistochemically in gynecologic tumors. The antigens were absent in the serous benign tumors of the ovary and in the normal ovarian tissues, whereas they were detected in some of the mucinous benign tumors. COTA and CSA were present and similarly distributed in most malignant epithelial tumors of the ovary, with their expression increasing with malignancy. Both antigens were almost completely absent in normal glands of the endometrium, but were expressed in many of the endometrial adenocarcinomas. Adenocarcinomas of the cervix were strongly positive for both antigens, and they were also detected in some of the normal cervical glands. However, no relationship was found between the expression of the two antigens and that of argyrophilia, an intestinal metaplasia.

An immunohistochemical study of small-cell and poorly differentiated carcinomas of the cervix using neuroendocrine markers

Small-cell and poorly differentiated carcinomas of the cervix were studied immunohistochemically for several neuroendocrine and epithelial markers. Neuroendocrine markers were frequently expressed in small-cell carcinomas with argyrophilia; of the seven such tumors, four were immunoreactive with anti-chromogranin, seven with antineuroendocrine, five with anti-Leu 7, and seven with anti-neuron-specific enolase. Only neuron-specific enolase, however, was expressed in two of the three small-cell carcinomas without argyrophilia. On the other hand, one of the epithelial markers, epithelial membrane antigen, was strongly positive in all three small-cell carcinomas without argyrophilia and all seven poorly differentiated carcinomas, while it was expressed only weakly and focally in all small-cell carcinomas with argyrophilia except in one case. In conclusion, it is suggested that the immunohistochemical demonstration of several neuroendocrine markers may be helpful in diagnosing neuroendocrine carcinoma of the cervix as a supplement to conventional light microscopy, silver staining, and electron microscopy.

[The clinical evaluation of sialyl Lewis Xi antigen in patients with gynecologic tumors]

In order to estimate the clinical significance of sialyl Lewis Xi (SLXi) antigen, the antigen was measured with an "FH-6" Otsuka Kit in sera from patients with various gynecologic tumors and healthy women. The antigen in ovarian cyst fluids was also determined. Furthermore, serum SLXi antigen levels were serially followed up in the patients with elevated serum SLXi levels to evaluate the correlation between serum SLXi levels and the response to treatment. Results obtained were as follows. 1) Among the patients with uterine myoma, uterine malignancies and benign ovarian tumors, the incidence of elevated serum SLXi antigen levels was very low. 2) Among the patients with ovarian malignancies, serum SLXi antigen levels was significantly increased in the following order: clinical stage I (38%), stage II (50%) and stage III (65%). 3) The high SLXi value was observed in the cyst fluid from all ovarian mucinous adenomas and all ovarian cancers. In addition SLXi antigen level was significantly higher in the cyst fluid of mucinous adenocarcinomas than that of serous cystadenocarcinomas. 4) Serum SLXi values were correlated with the effect of treatment. Interestingly, the elevation of serum SLXi levels preceded the clinical detection of recurrence by 3 month in a case. Thus SLXi antigen appears to be a useful marker for monitoring of ovarian malignancies, especially of mucinous adenocarcinomas.

An immunohistochemical study of neuroendocrine cells in gynecologic tumors

Various gynecologic tumors with argyrophilia were studied immunohistochemically for chromogranin using two antibodies, antichromogranin and antineuroendocrine. Of seven small cell carcinomas of the cervix, four were immunoreactive with antichromogranin and seven with antineuroendocrine. Argyrophil cells of six cervical adenocarcinomas were all immunoractive with both antibodies. Type I argyrophil cells of 20 endometrial carcinomas were likewise stained positively. However, of the 30 endometrial carcinomas with type II argyrophil cells, 19 showed positive immunoreactivity for chromogranin and 22 for neuroendocrine. Of the ovarian tumors tested, argyrophil cells of 11 mucinous tumors, three carcinoid tumors, and the pancreatic tissue of a malignant mixed germ cell tumor were all chromogranin- and neuroendocrine-immunoreactive. Type I argyrophil cells of five endometrioid carcinomas of the ovary were also immunoreactive with both antibodies. Of the 13 endometrioid carcinomas with type II argyrophil cells, only four showed positive immunoreactivity for chromogranin and only five for neuroendocrine. In conclusion, both antichromogranin and antineuroendocrine detect the specific neuroendocrine markers in close association with argyrophilia in gynecologic tumors, the latter being more sensitive for small cell carcinoma of the cervix, and for type II argyrophil cells in adenocarcinoma of the endometrium and endometrioid carcinoma of the ovary.

Effects of polycations on pulmonary vascular permeability in conscious sheep

The role of charged sites on the permeability characteristics of the pulmonary microvascular barrier were investigated using chronically instrumented unanesthetized sheep. In one series of experiments we studied the effects of the cationic amphiphile, dodecyl trimethylamine (DTA; 297 mol wt), and the anionic amphiphile, SDS (288 mol wt), on lung lymph flow rates (Ql), lung lymph to plasma protein ratios (L/P), pulmonary hemodynamics, and systemic hemodynamics. DTA significantly increased both Ql and L/P, whereas SDS had a more modest and transient effect on these variables. In a second series of experiments the polycations polybrene and poly-l-lysine were found to have very similar effects as those of DTA. In another series of experiments we tested the pretreatment inhibition potential of chlorpheniramine (an H1 receptor antagonist), dibutyryl-cyclic AMP (db-cAMP), and the calcium channel antagonists verapamil and nifedipine on polybrene-induced lung injury. We found that only verapamil and db-cAMP significantly attenuated the permeability effects of polybrene. We conclude that both cationic amphiphiles and polycations cause hemodynamic and permeability alterations in the pulmonary circulation of unanesthetized sheep. In addition, the permeability alterations induced by polybrene can be modulated by intracellular calcium and/or cAMP levels.

A nonsialylated high-molecular-weight glycoprotein defined by a monoclonal antibody to adenocarcinoma of the uterine endometrium

A murine monoclonal antibody, MCA-97, was prepared against a human endometrial adenocarcinoma cell line. In a cellular enzyme-linked immunospecific assay, the MCA-97 antibody reacted with all adenocarcinoma cell lines tested, including four endometrial adenocarcinoma lines. The antigen defined by MCA-97 was estimated to be a nonsialylated high-molecular-weight glycoprotein containing galactose and N-acetylglucosamine in its determinant. In immunoperoxidase staining of formalin-fixed, paraffin-embedded sections, MCA-97 reacted with most endometrial adenocarcinomas and ovarian endometrioid-type adenocarcinomas, and also reacted with normal glandular epithelium of the female genital and gastrointestinal tracts. However, it was mostly unreactive with squamous cell carcinoma and ovarian serous adenocarcinoma tissues. By the reversed passive hemagglutination method, the antigen defined by MCA-97 was detected in the sera of one-third of patients with endometrial adenocarcinomas, and in half of those with ovarian endometrioid adenocarcinomas. The antigen was not demonstrable in the sera of most normal female volunteers. Thus, MCA-97 monoclonal antibody has potential clinical applications in diagnostic serology and pathology.

Immunohistochemical demonstration of pancreatic secretory trypsin inhibitor in gynecologic tumors

Pancreatic secretory trypsin inhibitor (PSTI) is a specific trypsin inhibitor secreted by the acinar cells of the pancreas. Serum levels of immunoreactive PSTI have been reported elevated in patients with various malignancies including gynecologic tumors. The immunohistochemical localization of PSTI is studied in the comparison with argyrophilia and amylase immunoreactivity on 100 ovarian tumors, 35 endometrial carcinomas, and 34 cervical carcinomas. PSTI was noted in 19 of 85 common epithelial tumors of the ovary, being most frequently in mucinous tumors and less in endometrioid, but only occurred in immature pancreatic tissue of 1 of 15 germ cell tumors tested. In the uterus, 5 of 19 adenocarcinomas of the endometrium and 3 of 10 adenocarcinomas of the cervix were positive for PSTI immunoreactivity. PSTI was found more frequently in the tumors with argyrophil cells, especially of type I, but was related to the intestinal metaplasia and exocrine secretion rather than argyrophilia itself, judging from the different localization of PSTI and argyrophilic granules. No relationship was observed between amylase and PSTI immunoreactivity.

Climatic adaptation in thermogenesis and thermal insulation in wood mice (Apodemus argenteus)

Wood mice (Apodemus argenteus) were trapped live at three different altitudes (below 1,000, 1,900, and 2,400 m) during a 1-year period (Feb. 1984-Jan. 1985). After remaining at the trapped locations for 10-14 days, they were transferred into a climatic chamber at an altitude of 610 m. Oxygen consumption (VO2) and colonic temperature (Tco) were measured at chamber temperatures (Ta) of five steps (30, 20, 10, 0, and -10 degrees C) in freely moving conditions. In response to Ta of 0 degrees C for the mice trapped in winter when their mean local habitat temperature (Te) were lower than 0 degrees C, there was a significant inverse correlation between VO2 and Te (r = -0.70, p less than 0.001) whereas no significant correlation (r = 0.23) was observed in the mice trapped in other seasons when Te was higher than 0 degrees C. The correlation between Tco and Te was significant (r = -0.66, p less than 0.001) over the entire range of Te. The pelt weight of the mice trapped at Te higher than 0 degrees C had a significant inverse correlation with Te (r = -0.65, p less than 0.001), but not in the mice trapped at Te lower than 0 degrees C. After measurement of VO2 and Tco at Ta of 0 degrees C, the mice who had lived in colder habitats (below 0 degrees C) showed 0% mortality, whereas the mortality of the populations which had lived in warmer habitats was 13%. These results suggest that, in wood mice, adaptation to severe cold is established by an enhanced thermogenesis and by an increased insulation of the pelt in moderate cold.

[Phase II study of carboplatin in cervical carcinoma]

A phase II multi-center study of carboplatin for cervical carcinoma was carried out in 22 institutes throughout Japan. The patients registered consisted of 40 women with 39 cervical carcinomas and an endometrial carcinoma, of whom 31 were evaluable. Carboplatin was administered intravenously every 4 weeks at a dose of 400 mg/m2, in cases with no prior therapies and/or P.S. 0-1, and 300 mg/m2 in cases with prior therapies and/or P.S. 2-3. The overall response rate of 31 evaluable cases was 19.4% with 2 cases of CR and 4 cases of PR. The response rates by histological classification were 18.5% (5/27) for squamous cell carcinoma and 25.0% (1/4) for adenocarcinoma. Response rates analysed by lesion sites were 12.5% for primary tumors, 30.0% for local lesions and 20.0% for metastases. The response rate among patients without prior therapies was 14.3%, while those for patients with prior radiotherapy and for prior radiotherapy and chemotherapy were 33.3% and 13.3%, respectively. Major adverse effects observed were nausea and/or vomiting (52.9%), anorexia (44.1%) and malaise (35.3%). Hematologically, thrombocytopenia, leukopenia and anemia were frequently observed (52.9%, 35.3% and 32.4%, respectively). As for renal toxicity, elevation of BUN (2.9%) or serum creatinine (2.9%) and the decrease of creatinine clearance (14.3%) were observed, but they were mild, and tolerable. These results suggest that carboplatin is one of the most useful drugs against cervical carcinoma.

[Altered expression of Lewis antigens associated with malignant transformation in endometrial tissues]

Fetal, normal adult, and malignant tissues of the uterine endometrium were examined by immunoperoxidase staining for Lewis antigens. Pronounced expression of Lewis-a, Lewis-b, and Lewis-Y antigens in malignant tissues was observed, compared with that in normal adult tissues. Moreover, the amplified expression of Lewis-b antigen was considerably higher than that of Lewis-a and Lewis-Y antigens. On the other hand, Lewis-X antigen was less expressed in malignant tissues than in normal adult tissues. These results suggest that fucose-transferase activity might be increased in malignant tissues and that the type I carbohydrate chain may play a role in the malignant transformation. In addition, Lewis-b and Lewis-Y antigens can be considered to be oncofetal antigens since they were frequently expressed in fetal and malignant tissues, but not in normal adult tissues. However, the functional significance of these changes in the expression of Lewis antigens remains to be investigated.

Morphological differences in hearts of rats well adapted and poorly adapted to chronic hypoxia

We carried out an experiment to analyze morphological differences in hearts of rats well adapted and poorly adapted to chronic hypoxia. Male and female Wistar rats, 1 week, 4 weeks and 9 weeks old, were employed on the assumption that adaptive ability was dependent on age and sex. These rats were raised at an altitude of 2,400 m and were kept for 7 to 9 weeks. Control groups were maintained at an altitude of 600 m during the same period of time. Each group consisted of 4 to 6 rats. At the end of the experiment, body weight, heart weight, ratio of heart weight to body weight and hematocrit were measured, and ventricular wall thickness, myocardial fiber diameter, capillary supply and mitochondria were morphometrically studied. Of the 6 experimental groups, the 4-week-old male rats (M2) had the highest body weight, as compared with the other experimental groups. In addition, relative to these other experimental groups, the following features were found for M2. Heart weight was intermediate, heart weight/body weight ratio was low and hematocrit was also low. Ventricular wall thickness was intermediate in the right ventricle (RV) and interventricular septum (IVS) but was thin in the left ventricle (LV). Myocardial fiber diameter was intermediate in the RV, large in the IVS and small in the LV. Capillary supply was intermediate in the RV and dense in the IVS and LV. Mitochondria were small but cristal density and percentage area, estimated from electron micrographs, were found to be high.(ABSTRACT TRUNCATED AT 250 WORDS)