SPECIFIC HEAT of DEHYDRATED PULPS of FRUITS

Specific heat of dehydrated pulps, which were obtained from 31 different fruits at several moisture contents, was determined by the indirect mixing method. Data are reported for each fruit. They confirm the application of linear functions, especially at moisture contents above 50%. an exponential regression equation for calculation of specific heat in the whole range of moisture content was established using all the values.     

Promutagen activation by rodent-liver postmitochondrial fractions in the L5178Y/TK cell mutation assay

Individual S9 microsomal fractions prepared from normal livers of 8 rodent species or strains and from 1 rat strain pretreated with Aroclor 1254, were used to metabolize the promutagens N-acetyl-2-aminofluorene, 1,2-benzanthracene, benzo[a]pyrene, and 3-methylcholanthrene to active forms during 3-h co-incubation in the presence of L5178Y/TK+/- cells. The 8 compatible S9 preparations all converted each of the 4 chemical carcinogens into active mutagens with varied efficiencies except for the Aroclor-induced rat S9/benzanthracene combination which produced only weak activity. Aroclor induction did not notably enhance the mutagenicity of benzo[a]pyrene or 3-methylcholanthrene beyond that activity mediated by the other non-induced preparations. Syrian hamster S9 and, to a lesser degree, C57BL/6J mouse S9 were exceptionally active in converting N-acetyl-2-aminofluorene to toxic and mutagenic metabolites. One source of Swiss mouse liver (Blu : Ha ICR) provided the most active S9 when tested with the 3 polycyclic aromatic hydrocarbons. In general, mutagenicity and cytotoxicity were roughly correlated within S9 + promutagen combinations. Almost all of the methylcholanthrene metabolizing activity was lost by the 12th week when Aroclor-induced rat S9 was held at -20 degrees C, yet this activity remained constant when similar S9 was stored at -80 degrees C for 14 weeks. Surprisingly, some S9 sources including the induced rat-liver preparation converted anthracene to a weak or border-line mutagen. The activation of both 1,2-benzanthracene and anthracene may be linked within each species or strain although Aroclor induction enhanced anthracene mutagenicity yet attenuated the mutagenicity of 1,2-benzanthracene. Collectively, these data underscore the current inchoate state of development for S9 coupled somatic cell mutation assays.     

1,25-Dihydroxyvitamin D stimulation of specific membrane proteins in chick intestine

Vitamin D-deficient chicks were injected intracardially with physiological doses of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) and the formation of intestinal brush-border proteins was followed in vitro. Within 4 h of receiving the hormone the incorporation of radioactive leucine into at least two proteins in the brush-borders was increased. The apparent molecular weights of these proteins were 45 000 and 84 000. The change in the synthesis of these proteins was followed with time and compared with the concomitant changes in intestinal calcium transport. The relationship of these changes is such that there is a strong possibility that the proteins are involved in calcium absorption.     

Automated analysis of phencyclidine in urine by probability based matching GC/MS

A novel form of selected ion recording mass spectrometry using a microcomputer-managed mass spectrometer was employed to automatically identify and quantitate phencyclidine (PCP) in cyclohexane extracts of urine by Probability Based Matching. Seventy urine samples from known abusers were assayed for PCP content. The positively identified PCP concentrations ranged from 0.01 to 10.5 mug/ml for 65 samples, 26% of which fell in the 0.35-1.0 mug/ml range and 30% in the 1.0-3.4 mug/ml range. Five specimens had no detectable PCP (less than 10 mug/ml). Cyclohexane extraction efficiency for PCP in urine exceeded 95%. Selected ion monitoring was found to be necessary in order to avoid gas chromatographic interferences produced by co-elution of contaminants at the same retention time as PCP.