Effects of three retinoids on colon adenocarcinomas, sarcomas and hyperplastic polyps induced by intrarectal N-methyl-N-nitrosourea administration in male F344 rats

Male F344 rats, 9 weeks of age, were given multiple intrarectal administrations of N-methyl-N-nitrosourea (NMU) at 0.5 mg/dose twice a week for a total of 8, 12, or 16 doses. Five days after the final NMU instillation, rats were placed on one of four diets; chow with retinoid vehicle, chow with 654 mg N-ethylretinamide per kg diet, chow with 686 mg N-(2-hydroxethyl)retinamide per kg diet, or 406 mg retinylidene dimedone per kg diet. Groups of 40--50 rats receiving 16, 12, or 8 total doses were sacrificed 32, 44, or 52 weeks after the initial NMU dose, respectively. The number of rats with colon tumors and the number of tumors per tumor bearing rat in each dosage regimen was compared to appropriate controls. Organ weights for testis, liver, and kidneys were similar for controls and retinoid treated animals and no histopathologic lesions indicative of retinoid toxicity were found. Unusual proliferative lesions of the colon in rats of all dosed groups included hyperplastic and inflammatory polyps and sarcomas. The feeding of diets containing these three retinoids did not significantly modify the incidence or multiplicity of colon tumors observed under these conditions.

Tritium labeling of proteins to high specific radioactivity by reduction methylation

The third component of human complement, hemoglobin A2, and IgG have been radiolabeled with tritium to specific activities of 179, 103, and 89 Ci/mmol, respectively, by reductive methylation. The labeling procedure is mild, requiring only brief exposure to formaldehyde (10 to 12 mM) and tritiated sodium borohydride (3 to 5 mM), and specific for the alpha amino groups of NH2-terminal residues and epsilon-amino groups of lysyl residues. The extent of modification for each protein ranged between 5 and 16% at available amino groups based on a stoichiometric reactivity of 2 mol of formaldehyde/mol of primary amine. Although the degree of substitution required to obtain these specific activities was high, no significant loss of antigenic or biological activities was apparent. Each labeled protein was 90 to 95% precipitable with antiserum elicited to the unreacted protein. The hemolytic activity of C3 was reduced by only 16%; the oxygen affinity of HbA2 was minimally decreased, and the phosphorylcholine binding affinity of an IgA myeloma protein (TEPC-15) was not significantly affected. Precise double antibody radioimmunoassays were developed with each tritiated protein capable of detecting less than 10(-8) g of antigen. Labeled protein samples have been stored for time periods up to 1 year without appreciable deterioration.

Conformation-specific antibodies to the alpha chain COOH terminus of hemoglobin A0

An anti-hemoglobin antiserum obtained from a sheep immunized with human carboxyhemoglobin A0 demonstrated little difference in its reactivity with deoxy- or carboxyhemoglobin A0. However, a subpopulation of this antiserum isolated by synthetic peptide affinity chromatography clearly distinguished between these two hemoglobin species. This subpopulation, designated alpha(129-141) anti-hemoglobin antibodies, represents less than 1% of the total anti-hemoglobin antibodies. They are nonprecipitating by Ouchterlony analysis, and fluorescence-quenching studies demonstrate the interaction of a single antibody binding site per hemoglobin dimer. These antibodies bind preferentially to carboxyhemoglobin with a median affinity constant of 5 X 10(8) M-1 compared to binding to deoxyhemoglobin with a binding affinity of less than 1 X 10(8) M-1. Furthermore, the presence of these antibodies in stoichiometric amounts increases the oxygen affinity of hemoglobin, and thus antibody and oxygen binding to hemoglobin can be considered as a linked function.

Nabilone: a potent antiemetic cannabinol with minimal euphoria

Nabilone is a cannabinol derivative which has potent central antiemetic effects in animals. We observed that the drug significantly reduced the nausea and vomiting induced by cancer chemotherapy in 10 of 13 patients who were refractory to conventional antiemetics. A dose-response effect was apparent. The drug was generally well-tolerated, although it also had sedative effects. Additionally, dizziness, decreased coordination and postural hypotension were observed in some patients. Euphoric effects of the agent were minimal at antiemetic dosage levels.

Reactivity of fibrinogen and fibrinopeptide A containing fibrinogen fragments with antisera to fibrinopeptide A

Two antisera used in the radioimmunoassay for human fibrinopeptide A (FPA) which appear to have different immunochemical specificities have been tested for cross-reactivity with fibrinogen and with three fragments of fibrinogen which contain the FPA sequence. These fragments were the three-chain, NH2-terminal disulfide knot (N-DSK) produced by CNBr cleavage of fibrinogen, the reduced, carboxymethyl Aalpha chain portion of the N-DSK, and fragment E produced by plasmin digestion of fibrinogen. One antiserum (R-2) showed high specificity for free FPA and less than 2% cross-reactivity with fibrinogen or the FPA-containing fragments. The other antiserum (R-33) possessed a much higher degree of cross-reactivity with the FPA-containing fragments. Synthetic and native fibrinopeptides were found to be indistinguishable in the assay system with either antiserum. As a result of these studies, an hypothesis has been developed concerning the nature of the antigenic determinants on FPA which favor measurement of free FPA and limit cross-reactivity with larger, FPA-containing peptides.

Hodgkin's disease in siblings: a family study

Hodgkin's disease may sporadically occur in more than one member of a family. A family in which two siblings were documented to have the nodular sclerosing form of the disease was studied for immunological competency, distribution of HL-A antigens, and Epstein-Barr virus (EBV) antibody titers. All family members examined, except the living individual with HD, had no significant abnormality in humoral and cellular immunity. HL-A antigens previously reported to appear in Hodgkin's disease with increased frequency were not found. Antibody titers to the viral capsid antigen of EBV were normal. Therefore, none of the genetically associated laboratory tests related to cancer (particularly Hodgkin's disease) were found in this family. The evidence from this family thus supports the probable importance of environmental factors in the etiology of Hodgkin's disease, particularly in the nodular sclerosis group.