Evidence for inhibition of growth related to compromised DNA synthesis in the interaction of daunorubicin with H-35 rat hepatoma

The H-35 rat hepatoma is relatively insensitive to the anthracycline antibiotic, daunorubicin (DNR), requiring 0.25 microM daunorubicin for inhibition of cell proliferation by 50%. Studies were undertaken to investigate the basis for the apparent intrinsic resistance in this cell line. The relative insensitivity of the H-35 cells to DNR is not a function of metabolic inactivation of DNR to deoxyaglycone derivatives; after a 2-h incubation, less than 10% of drug is metabolized, exclusively by conversion to daunorubicinol. The limited toxicity of DNR to the rat hepatoma may be explained, in part, by the absence of DNA strand breaks at daunorubicin concentrations up to 1 microM while higher (supraclinical) DNR concentrations (5 and 10 microM) produce direct, "non-protein-associated" DNA strand breaks. Limited daunorubicin toxicity in this tumor cell line may also be related to the apparent absence of free radical-mediated cellular damage as the free radical scavengers dimethyl sulfoxide, catalase, methanol, and mannitol fail to reverse the inhibitory effect of 1 microM DNR on cell proliferation. Daunorubicin does not induce leakage of the cytoplasmic enzyme, glutamic oxaloacetate transaminase, or diminish mitochondrial enzyme function. Conversely, while drug effects on RNA synthesis are small, and protein synthesis is minimally diminished, inhibition of cell proliferation corresponds closely with inhibition of DNA synthesis.

Synthesis and biological activity of several amino nucleoside-platinum(II) complexes

Several platinum(II) complexes of 3',5'-diamino-3',5'-dideoxythymidine (compound 1), 5'-amino-5'-deoxythymidine (compound 2), and 3'-amino-3'-deoxythymidine (compound 3) and the respective 2'-deoxyuridine amino nucleoside complexes, 4-6, have been synthesized. Whereas compounds 1, 2, and 4-6 had no inhibitory effect on the replication of murine L1210 cells in cell culture, compound 3 [(3'-AdThd)2PtCl2] inhibited these cells with an ED50 of 0.8 microM. Incubation of L1210 cells with 10-20 microM compound 3 for 2 h produced less than 18% inhibition of RNA, DNA, or protein synthesis, which is of questionable significance. However a 16-h incubation resulted in an increased uptake of labeled thymidine into DNA (77%), labeled uridine into RNA (17%), and labeled amino acids into protein (100%). These unexpected results indicate that inhibition of macromolecules may not be involved in the inhibition of the replication of L1210 cells. The increased incorporation of labeled metabolites into macromolecules may be related to the increase in cell volume after a 2-h incubation of L1210 cells with compound 3 plus a marked increase after 2 h in the proportion of cells in their S phase. Compound 3 appears to delay the progression of cells through their cell cycle. A marked inhibitory effect on the transport of methionine or aminoisobutyric acid into L1210 cells was found with compound 3, which was slightly greater than that produced with cisplatin. Compound 3 had a dose-dependent effect on the survival of mice bearing the L1210 ascites neoplasm, with a T/C X 100 of 175 at a dose of 320 mg/kg. Investigation of the kinetics of decomposition in aqueous systems demonstrated that the primary UV-absorbing decomposition product is 3'-amino-3'-deoxythymidine and that only a limited amount of the compound is formed (less than 8%). Although 3'-amino-3'-deoxythymidine could account for a part of the inhibition of the replication of L1210 cells in culture, it cannot account for the inhibition of amino acid transport by compound 3, the platinum complex of 3'-amino-3'-deoxythymidine. Compound 3 has been shown to limit part of the amino acid uptake into L1210 cells in a similar manner to cisplatin.

Who cares what care?: an inverse interest law?

The paper attempts to systematise some of the ideas on medical dominance as the inverse interest law, which is broadly seen as the more commonplace the problem and the more people affected, the less will be the medical interest. The law or rather laws are exemplified by reference to the symptom iceberg, health education and welfare, hospital expenditure, priority groups and community care and class, locality and ethnicity. The inverse interest laws, which ensure the operation of the inverse care law, are seen as products of medicine definition and practice in relation to their containing society.

Comparison of mesna with forced diuresis to prevent cyclophosphamide induced haemorrhagic cystitis in marrow transplantation: a prospective randomised study

A prospective randomised study was carried out to compare the effect of mesna (2-mercaptoethane sulphonate sodium) with that of forced diuresis in preventing cyclophosphamide induced haemorrhagic cystitis in marrow transplant recipients. Sixty-one consecutive BMT recipients were randomised for treatment with forced diuresis or mesna. The incidence of macroscopic haematuria was significantly lower in the mesna treated group (chi 2 = 4.03, P less than 0.05). No specific side effects of mesna were detected. The lymphopenia induced by cyclophosphamide in the aplastic recipients was similar in the mesna and forced diuresis groups suggesting that mesna has no effect on the lymphocytotoxic activity of cyclophosphamide, although 6 out of 7 episodes of graft failure documented in the study occurred in mesna treated patients. As a result of this study our present policy is to use mesna in all BMT recipients but to continue careful documentation of the incidence of graft failure.

Pseudoxanthoma elasticum in South Africa--genetic and clinical implications

After investigation by a multidisciplinary team, 19 cases of biopsy-proven pseudoxanthoma elasticum are described. Evidence for an increased gene frequency in the Afrikaner population was found, as was support for the claim of genetic heterogeneity in the disorder. The well-described clinical manifestations involving the eyes, skin and cardiovascular system were seen, as were more rarely reported features such as acne, telangiectasia of the lips and bilateral cataracts. Mitral valve prolapse and gastro-intestinal haemorrhage were not found in our patients, although there are several reports in the literature.

Eosinophilic myeloproliferative disorder in a horse

An eosinophilic myeloproliferative disorder resulted in edema and hemorrhagic diathesis in a 10-month-old Standardbred colt. Laboratory abnormalities included severe thrombocytopenia, anemia, mild hypoproteinemia, and marked eosinophilia. Circulating eosinophils were immature or atypical with variation in granule size, disproportionate nuclear to cytoplasmic maturation, and abnormal nuclear size and shape. Bone marrow aspirate had mainly atypical eosinophil precursors, few erythroid precursors, and no megakaryocytes. A blood transfusion and dexamethasone therapy resulted in some improvement; however, the horse was euthanatized due to poor prognosis. Postmortem examination showed gastrointestinal parasitism; histologically the spleen was infiltrated by atypical eosinophils and there were sites of eosinophilopoiesis. The disease was broadly similar to idiopathic hypereosinophilic syndrome in people, but typical cardiac and neurologic involvement of hypereosinophilic syndrome were absent. Progressive myelophthesis and marked eosinophil atypia suggested malignancy.

More aggressive cartoons are funnier

Independent rankings of humor and aggressiveness were obtained for sets of cartoons drawn randomly from two different magazines. The correlation of median humor and median aggressiveness rankings ranged from .49 to .90 in six studies involving six different sets of cartoons and six different groups of subjects, including children and adults, high and low socioeconomic status (SES) individuals, and native- and foreign-born individuals. This correlation is consistent with Freudian, arousal, and superiority theories of humor. Another prediction of Freudian theory, that high-SES subjects should be more appreciative of aggressive humor than low-SES subjects, was not supported.

More aggressive cartoons are funnier

Independent rankings of humor and aggressiveness were obtained for sets of cartoons drawn randomly from two different magazines. The correlation of median humor and median aggressiveness rankings ranged from .49 to .90 in six studies involving six different sets of cartoons and six different groups of subjects, including children and adults, high and low socioeconomic status (SES) individuals, and native- and foreign-born individuals. This correlation is consistent with Freudian, arousal, and superiority theories of humor. Another prediction of Freudian theory, that high-SES subjects should be more appreciative of aggressive humor than low-SES subjects, was not supported.