Aggregation of secreted amyloid beta-protein into sodium dodecyl sulfate-stable oligomers in cell culture.

Filamentous aggregates of the 40-42-residue amyloid beta-protein (A beta) accumulate progressively in the limbic and cerebral cortex in Alzheimer's disease, where they are intimately associated with neuronal and glial cytopathology. Attempts to model this cytotoxicity in vitro using synthetic peptides have shown that monomeric A beta is relatively inert, whereas aggregated A beta reproducibly exerts a variety of neurotoxic effects. The processes that mediate the conversion of monomeric A beta into a toxic aggregated state are thus of great interest. Previous studies of this conversion have employed high concentrations (10(-5)-10(-3) M) of synthetic A beta peptides under nonbiological conditions. We report here the detection of small amounts (< 10(-9) M) of SDS-stable A beta oligomers in the culture media of Chinese hamster ovary cells expressing endogenous or transfected amyloid beta-protein precursor genes. The identity of these oligomers (primarily dimers and trimers) was established by immunoprecipitation with a panel of A beta antibodies, by electrophoretic comigration with synthetic A beta oligomers, and by amino acid sequencing. The oligomeric A beta species comprised approximately 10-20% of the total immunoprecipitable A beta in these cultures. A truncated A beta species beginning at Arg 5 was enriched in the oligomers, suggesting that amino-terminal heterogeneity can influence A beta oligomerization in this system. Addition of Congo red (10 microM) during metabolic labeling of the cells led to increased monomeric and decreased oligomeric A beta. The ability to detect and quantitate oligomers of secreted A beta peptides in cell culture should facilitate dynamic studies of the critical process of initial A beta aggregation under physiological conditions.

Inversion of chromosome 16 and dysplastic eosinophils in accelerated phase of chronic myeloid leukemia.

Abnormalities of chromosome 16, including inv(16)(p13q22), del(16)(q22), and t(16;16)(p13;q22), have been reported almost exclusively in association with acute myelomonocytic leukemia and are characteristically accompanied by abnormal eosinophils with dysplastic granules in the bone marrow. We observed an inv(16)(p13q22) in two patients with typical Philadelphia chromosome positive chronic myeloid leukemia (CML). The appearance of the abnormality of chromosome 16 was associated with acceleration of disease or onset of blast crisis and with the appearance in the bone marrow of abnormal eosinophils. In both cases the marrow karyotypes were 46,XY,t(9;22)(q34;q11)/46,XY,inv(16)(p13q22),t(9;22)(q34;q11). In these two patients the temporal association of the acquisition of the inversion 16 and the appearance of monocytoid cells and dysplastic eosinophils in the bone marrow further supports the relationship of this karyotypic abnormality with leukemic monocytoid and eosinophilic evolution. This secondary cytogenetic change appears to be an infrequent manifestation of specific phenotypic disease progression in CML.

Infection in the myelodysplastic syndromes.

PURPOSE: To determine the incidence, characteristics, and outcome of infection in patients with myelodysplastic syndromes (MDS) and risk factors that may lead to infection. PATIENTS AND METHODS: We reviewed infections that occurred in 86 consecutive patients with MDS who received care from 1968 to 1986 at a university-affiliated Veterans Affairs Medical Center. Time lines charting the course of each patient with MDS were created and included infections, MDS subgroup at the time of presentation and at the time of each infection, peripheral neutrophil counts, and therapies for MDS. RESULTS: Infections occurred at a rate of nearly one per patient year of observation. Infection rates were associated with MDS subgroup as follows: refractory anemia with or without ringed sideroblasts (RA +/- RS) less than refractory anemia with excess blasts (RAEB) less than RAEB in transformation (RAEB-T). The group of RA +/- RS patients who had erythroid abnormalities but minimal or no dyspoiesis of other cell lines had the lowest rate of infections. Infection rates were higher in patients with less than or equal to 1,000 neutrophils/microL blood than in patients with greater than 1,000 neutrophils/microL blood for each classifiable MDS subgroup. Neutrophil concentration and MDS subgroup were independent risk factors for infection in patients with MDS. Bacterial pneumonias and skin abscesses were the most common infections. Infection was the most common cause of death during MDS, accounting for 64% of deaths, and was more common than transformation to acute leukemia as a cause of death. CONCLUSION: Infection is a common, life-threatening problem in patients with MDS. Neutropenia and MDS subgroup are each risk factors for infection. Clinicians should aggressively evaluate patients with fever and MDS for infection, especially pneumonia and skin infections.

Refined chromosome study helps define prognostic subgroups in most patients with primary myelodysplastic syndrome and acute myelogenous leukaemia.

Based on a 6 1/2-year study of 284 consecutive adult patients with primary myelodysplastic syndrome (MDS) and and acute myelogenous leukaemia (AML), we have found that refined chromosome analysis can be used as an independent prognostic indicator in the great majority of patients with MDS and AML. In MDS, the FAB subtype was also found to have prognostic value and this was enhanced when the chromosomal findings were taken into consideration. In AML, the age of the patient correlated more closely with the chromosomal changes in predicting prognosis in most patients than did the FAB classification. Previously we reported that refined chromosome analysis of bone marrow specimens from 161 adult patients with primary or non-therapy related MDS and AML identified three prognostic chromosomal categories in each disease, representing 40% of all patients (Yunis et al, 1984, 1986). By extending our study to 284 patients, as well as a longer follow-up, it was possible to determine the prognostic implications of two additional chromosomal categories in MDS and five in AML. Since 73% of all patients are now represented in well-defined chromosomal subgroups with prognostic significance, refined chromosome analysis emerges as a tool that could have considerable impact in protocols.

Refined chromosome analysis as an independent prognostic indicator in de novo myelodysplastic syndromes.

In a study of 56 consecutive adult patients with de novo myelodysplastic syndromes (MDS), all cases were successfully analyzed with two refined chromosome banding techniques. Most patients (44 of 56, 79%) were found to have a chromosome defect. The majority of these patients had a recurrent loss of chromosomal material rather than a reciprocal translocation or inversion, as commonly found in acute leukemia. The three largest chromosomal categories found were associated with a wide range of survival. Twelve patients (21%) had normal chromosomes, a stable clinical course, and long survival (median follow-up time of 49 months, with all patients alive). Nine patients had in common a single chromosome defect resulting in either monosomy 7 or deletion 7q. They had a median survival of 12 months, and four died of acute nonlymphocytic leukemia (ANLL). Of 12 patients with complex defects, 11 had a complete or partial loss of a chromosome 5 and a complete or partial loss of the long arm of a chromosome 7 or 20. They had a poor median survival of four months, and six patients died of ANLL. Although the French-American-British (FAB) classification was also found to have some prognostic value, FAB subgroups were chromosomally heterogeneous and showed less dramatic differences in median survival than the larger chromosomal subgroups. We have shown, for the first time, that a refined chromosomal analysis is an independent prognostic indicator in de novo MDS and may be helpful in establishing therapeutic approaches in this difficult group of heterogeneous disorders.

Chronic myelodysplastic syndrome: short survival with or without evolution to acute leukaemia.

The myelodysplastic syndromes represent a prognostically diverse group of disorders. Their study has recently been facilitated by the classification proposed by the French-American-British (FAB) Cooperative Group. Using this scheme it is now possible to define more precisely their natural history and clinical relationship to acute leukaemia. Using the longitudinal case control technique, we reviewed the clinical data and morphology of 69 patients (all elderly males) with chronic irreversible haematological cytopenia and dysplasia. Applying FAB criteria we found: refractory anaemia (RA) in 43%; sideroblastic anaemia (RA-S) in 33%; refractory anaemia with excess blasts (RAEB) in 13%; RAEB in transformation (RAEB-T) in 9% and chronic myelomonocytic leukaemia (CMML) in 1%. The median survival for the entire group was 27 months (RA, 52; RA-S, 29; RAEB, 12; RAEB-T 11; and CMML, 2 months). Short survival was predicted by transfusion requirement and other manifestations of severe cytopenia, as well as by myeloid immaturity. The presence or absence of sideroblastosis did not correlate with survival. Acute leukaemia developed in only eight patients (12%), six of whom initially had RA. Leukaemic transformation was not predicted by progressive cytological immaturity. This study demonstrates that even in the absence of leukaemic transformation, chronic myelodysplasia is a lethal haematological disorder.

Non-Hodgkin's lymphoma after treatment for Hodgkin's disease.

A patient is described who developed a diffuse histiocytic lymphoma (DHL) 9 years after radiation therapy for Hodgkin's disease. This occurrence is of particular interest because the treatment for Hodgkin's disease included no chemotherapy and the second tumor appeared to originate remote from the irradiated site. Thus, the role of Hodgkin's disease treatment in the etiology of this patient's second lymphoma appears doubtful. The development of DHL in this patient could represent an unrelated event or conceivably an event facilitated by Hodgkin's disease itself.

Auer rod positive dysmyelopoietic syndrome.

Twenty-five patients with refractory anemia with excess blasts (RAEB) were studied. Five of these patients showed Auer rods in their myeloblasts, but met other criteria for RAEB. Median survival of the Auer rod-positive group was 14 months (range 2-27) from diagnosis with survival of 7 months after Auer rods were first observed. Median survival for the Auer rod-negative group was 12 months. Two patients developed overt acute leukemia, both from the Auer rod-negative group. The clinical course of Auer rod-positive RAEB, like that of Auer rod-negative RAEB, was one of progressive bone marrow failure complicated by infection, serious bleeding and the development of absolute transfusion requirement. These findings suggest that Auer rod-positive RAEB is a morphologic variant dysmyelopoietic syndrome that may pursue a similar clinical course to Auer rod-negative disease. Formulation of a separate treatment approach for those RAEB patients who possess Auer rods would appear ill advised.

Granulocytic sarcoma: a clinicopathologic study of 61 biopsied cases.

Granulocytic sarcoma is an uncommon tumor composed of granulocytic precursor cells. Because it occurs in a variety of clinical settings and because the tumor cells are primitive it is frequently unrecognized during life. This presentation details the authors' experience with 61 biopsy-proven granulocytic sarcomas. The patient age range was from 2 to 81 years (mean 48 years). In eight patients the tumors were multiple. Most common sites of involvement were bone, periosteum, soft tissue, lymph node and skin. Twenty-two tumors occurred in 15 patients with no known disease, 26 occurred in 24 patients with a known myeloproliferative disorder, and 13 occurred in 11 patients with proven acute myeloid leukemia. Thirteen of the 15 patients with no known disease developed acute leukemia in from one to 49 months after the biopsy of their tumors (mean 10 months). Most tumors occurring in patients with a known myeloproliferative disorder were associated with blast crisis. The authors' cases displayed a morphologic range from well-differentiated to those tumors that displayed virtually no evidence of differentiation by conventional microscopy. It was therefore not surprising that most tumors were originally diagnosed as lymphoma. Chloro-acetate esterase (CAE) stains were performed on 56 tumors and 47 were studied with antilysozyme immunoperoxidase technique. Fifty-six of the 57 specimens studied by either technique were positive. Antilysozyme immunoperoxidase stains were particularly useful in confirming the diagnosis.

Richter's syndrome in chronic lymphocytic leukemia.

Over an 18-year period a distinctive large cell lymphoreticular neoplasm (Richter's transformation) developed in 9 patients with chronic lymphocytic leukemia. Clinical findings at the onset of Richter's transformation were remarkably uniform and consisted of the abrupt onset of fever, marked asymmetric lymphadenopathy with the formation of masses, splenomegaly, and hepatomegaly. All patients underwent rapid clinical deterioration followed by death within six and a half months. Earliest infiltrates of large lymphoreticular cells were identified in the lymph nodes in 3 of 4 patients and the bone marrow in 3 of 9 patients, while no patient had peripheral blood involvement. Autopsy examinations revealed extensive infiltrates of large lymphoreticular cells, predominantly in bone marrow, lymph nodes, liver, spleen, but also in kidney, lung, and gastrointestinal tract. In each case, these large lymphoblast-like and pleomorphic lymphoreticular cells were admixed with mature-appearing lymphocytes and intermediate forms (prolymphocytes). Electron microscopic and immunoperoxidase studies provided additional evidence that this highly aggressive lymphoreticular neoplasm represents a transformation or dedifferentiation of chronic lymphocytic leukemia.

Inhibitory effect of disulfiram on rat mammary tumor induction by N-2-fluorenylacetamide and on its metabolic conversion to N-hydroxy-N-2-fluorenylacetamide.

The effect of an antioxidant, disulfiram (DSF), on the carcinogenicities of N-2-fluorenylacetamide (2-FAA) and N-hydroxy-N-2-fluorenylacetamide (N-OH-2-FAA) was examined. DSF given in a diet at a concentration of 0.9% for 1 week before and throughout the carcinogen treatment (0.1 mmol/kg 3 times a week for 4 weeks) reduced the incidence of mammary tumors induced with 2-FAA by 50% and extended the mean latency period of malignant tumors from 5 to 10 months. By contrast, DSF had no effect on mammary carcinogenesis by N-OH-2-FAA. Consistent with these results was the demonstration of the inhibitory effect of DSF on the first step of metabolic activation of 2-FAA, i.e., N-hydroxylation. N-hydroxylation of 2-FAA was significantly inhibited in hepatic microsomes of untreated and 2-FAA-treated male and female rats by DSF given orally. A similar inhibition was shown in vitro after preincubation of hepatic microsomes with DSF. Measurements of cytochrome P450 after pretreatment of rats or microsomes with the inhibition showed no appreciable changes in the hemoprotein content. It was concluded, therefore, that the inhibitory effect of DSF on N-hydroxylation of 2-FAA is accomplished through mechanism(s) other than depression of the cytochrome P450 level. Because both 2-FAA and DSF bind to cytochrome P450 producing a type I spectrum, DSF may interfere with the binding of 2-FAA and thus alter its metabolism.

Chronic lymphocytic leukemia in association with a second lymphoproliferative disorder: response to chemotherapy in two cases.

The development of either histiocytic lymphoma or Hodgkin disease in association with pre-existing chronic lymphocytic leukemia has been described in the literature as a terminal event. We describe two patients in whom the diagnosis of a second malignant lymphoma was made during life and who achieved objective clinical response after a change in therapy to a more aggressive combination of drugs. We conclude that patients with chronic lymphocytic leukemia who have had a sudden change in their clinical course should have thorough reevaluation, looking specifically for the development of a second lymphoproliferative disorder. If this is discovered, more aggressive therapy should be initiated.

Studies on the transformation of rat embryo cells of low passage by carcinogenic fluorenylhydroxamic acids and their acetate esters.

Rat embryo cells of low passage subjected to a single treatment with certain carcinogenic fluorenylhydroxamic acids and their respective acetate esters showed signs of transformation in vitro, such as changes in phenotype, growth in soft agar and agglutination with concanavalin A. In addition, certain changes in karyotype and loss of diploidy were observed. There was no evidence, either by electron microscopy or by assay of RNA-dependent DNA polymerase, for the presence of virus. None of these cell lines produced tumors after inoculation into the isologous host. The results of these study lead us to suggest that malignant transformation is a multistep process and that certain criteria of transformation of rat embryo cells are associated with the initial stage(s) in which the cells are transformed without being tumorigenic. The ultimate test for malignant transformation of rat embryo cells remains the production of tumors in a susceptible host after inoculation of treated cells.

Lack of susceptibility of F344 rats to mammary tumor induction by topically applied fluorenylacetohydroxamic acids and their acetates.

Carcinogenicity of N-hydroxy-N-3-fluorenylacetamide for the mammary glands of female inbred F344 rats was examined after systemic and topical administration. The compound given ip produced a 60% mammary tumor incidence but was only marginally active after topical application. Female F344 rats did not develop mammary tumors after topical application of N-hydroxy-N-2-fluorenylacetamide, N-acetoxy-N-2-fluorenylacetamide, or N-acetoxy-N-3-fluorenylacetamide. These results contrasted with those reported earlier for female Sprague-Dawley rats and indicated differences in susceptibility of the mammary glands of these rat strains to tumor induction by these carcinogens.

Mammary carcinogenesis in the rat by topical application of fluorenylhydroxamic acids and their acetates.

This work confirms the previous observation that a single application of N-hydroxy-2-fluorenylacetamide or N-hydroxy-3-fluorenylacetamide to the mammary gland of the rat induced a high incidence of tumors, whereas the corresponding arylamides, N-2-fluorenylacetamide (2-FAA) and N-3-fluorenylacetamide, were only weakly active. The results suggested N-hydroxylation of the arylamides as a prerequisite for mammary carcinogenesis. Since N-hydroxylation of 2-FAA by hepatic microsomes is catalyzed by the mixed-function oxidase containing cytochrome P-450 or the 2-methylcholanthrene-inducible cytochrome P1-450, we examined whether these cytochromes are present in mammary microsomes. In contrast to liver, neither cytochrome nor N-hydroxylation of 2-FAA was detected in the mammary gland of normal and 3-methylcholanthrene-treated rats. These experiments indicated that the N-hydroxylation of 2-FAA, although obligatory for induction of mammary neoplasia, is not performed in the mammary gland but may take place in the liver. We also examined the carcinogenicity of N-acetoxy-2-fluorenylacetamide and N-acetoxy-3-fluorenylacetamide for the mammary gland upon topical application. Since both acetates were carcinogenic and since the acetyl group of acetyl coenzyme A is transferred to fluorenylhydroxamic acids at pH 7.4, these esters may be ultimate carciogens in mammary carcinogenesis. Ovariectomized rats did not develop mammary tumors after a single application of the fluorenylhydroxamic acids, and administration of estradiol and fluorenylhydroxamic acids to the ovariectomized rats did not improve the tumor yield. These results indicate that induction of mammary tumors by fluorenylhydroxamic acids is under hormonal control.