Changes in collagen with age. V. Modification of mouse skin collagen by whole body x-irradiation

Male mice (SM/J), age 26–33 weeks, were exposed to 0·6 krads of whole body X-irradiation and sacrificed 36 weeks later. The skins were removed and the neutral salt soluble (NSC), acid soluble (ASC), and insoluble (ISC) collagen fractions were isolated. The results obtained on examination of these three fractions suggest that exposure to X-irradiation results in an increased lability of the insoluble collagen matrix and a deposition of non-collagenous proteins.     

Primary intracranial neoplasms of infancy and early childhood

We investigated the age-related location, gender distribution, and histology of 107 brain tumors in children under 4 years of age seen in our department between 1984 and 1997. The male-to-female ratio was 1.4 (62/45 cases) with a prevalence of supratentorial tumors (60/47=1.3); the main histological entity was astrocytoma (33.6%), followed by ependymoma (14.0%). In the 1st year of life 22 cerebral neoplasms became clinically apparent. A higher ratio for supratentorial tumors was revealed (17/5=3.4), but without gender preference, and primitive neuroectodermal tumors (PNET) were the most frequent (5/22). In the 2nd year 25 tumors were found. The male-to-female ratio was 1.5 (15/10) and the supratentorial-to-infratentorial ratio, 1.1 (13/12). The two most common entities were astrocytoma and ependymoma (6 cases each). In addition, a survey of previously published investigations into this subject was performed and a compilation of data on 1960, 545 and 1084 tumors in children below the age of 1, 2 and 4 years, respectively, was prepared, which makes it the most extensive review of brain tumors of infancy and early childhood yet undertaken. Received: 14 July 1997     

Hepatocellular carcinoma: assessment of resectability by computed tomography and ultrasound

A retrospective review of the CT and ultrasound scans from examinations of 30 patients who had hepatocellular carcinoma (hepatoma) was undertaken with special emphasis placed on evaluation of hepatic distribution of tumor, vascular invasion, and extrahepatic spread. Although both CT and ultrasound detected hepatoma in 29 of 30 patients (96%), CT showed more extensive hepatic parenchymal involvement in eight of the patients. Vascular invasion was seen more frequently with ultrasound than with CT. Invasion into the main portal vein was seen by ultrasound in 11 of 30 patients (37%). Extrahepatic spread of tumor was much more frequently detected by CT and was present in 21 of 30 patients (70%). A reasoned approach to the diagnostic workup of hepatomas that will minimize invasive procedures and unnecessary surgery is presented.     

A Color-Matching Technique for Monitoring Tar/Nicotine Yields to Smokers

We describe a technique that enables individuals to detect the number of puffs taken on a filter cigarette by comparing the “color” of the spent filter to a color scale that simulates the appearance of filters exposed to low-, standard-, or high-yield smoking-machine regimens. Average ratings of filters by 11 subjects correlated almost perfectly with the number of standard puffs to which the filters had been exposed. (Am J Public Health 1982; 72:597-599.)     

Metabolism and excretion of 2,4-[14C]dinitrotoluene in conventional and axenic Fischer-344 rats

Comparisons of in vitro reduction of 2,4-dinitrotoluene (2,4-DNT) by cecal microflora and liver have indicated that microflora may play a large role in the in vivo metabolism of 2,4-DNT to reduced metabolites. Furthermore, reduction of 2,4-DNT by cecal microflora produces nitroso and, presumably, hydroxylamino intermediates which may account for the toxic actions of 2,4-DNT, including hepatocarcinogenesis. This study examines the metabolism, excretion, and hepatic covalent binding of 2,4-DNT in conventional, DNT-fed, and axenic Fischer-344 rats in order to define more precisely the role of DNT pretreatment and intestinal microflora in the disposition and toxicity of 2,4-DNT. No differences in 2,4-DNT disposition were produced by 30 days of feeding DNT (35 mg/kg/day) in the diet of male or female rats. Axenic males and females excreted less of a dose of 2,4-DNT in the urine than did conventional animals, and half-times for excretion of 4-(N-acetyl)amino-2-nitrobenzoic acid (4NAC2NBA), 2,4-dinitrobenzoic acid, 2-amino-4-nitrobenzoic acid (2A4NBA), and 2,4-dinitrobenzyl alcohol glucuronide were longer in axenic males than in conventional males. In axenic females half-times for excretion of only 4NAC2NBA and 2A4NBA were longer than in conventional females. Amounts of 4NAC2NBA and 2A4NBA excreted by axenic animals were 1/10th to 1/5th those excreted by conventional animals. Hepatic covalent binding was decreased by half in axenic animals. These data suggest that intestinal microflora play a major role in the appearance of reduced urinary metabolites and of covalently bound material after 2,4-DNT administration.     

Estimating the hazards of "less hazardous" cigarettes. III. A study of the effect of various smoking conditions on yields of hydrogen cyanide and cigarette tar

A brand of cigarette with nominal tar and nicotine yields of 4.0 mg and 0.4 mg, respectively, was examined under various machine-smoked conditions that reflect the wide range of human smoking behavior. Three levels of each of five smoking parameters--butt length, puff duration, puff interval, puff volume, and ventilation occlusion--were examined, and the effects on puff number and total particulate matter (TPM) as well as gas phase, particulate phase, and total HCN yields were estimated. Yields of hydrogen cyanide (a ciliatoxic agent) and TPM varied significantly under different smoking conditions. Ventilation occlusion had the most pronounced effect, accounting for 34% of the response variation of TPM yields and 42% of the response variation for total hydrogen cyanide yields. In the survey of available brands, total hydrogen cyanide yields varied from 2 to 233 micrograms/cigarette for the 115 brands tested, a range less than that observed for a single brand smoked under various nonstandard conditions, providing a possible explanation for the previously noted lack of correspondence between HCN yields under standard conditions and levels of thiocyanate in samples of smokers' plasma and saliva. In addition, hydrogen cyanide yields and efficiency of filters in removing HCN were examined under standard smoking conditions. Acetate filters, the most common variety, were found to remove an average of about 14% of the hydrogen cyanide from the mainstream smoke.     

Further structural analysis of rat liver microsomal metabolites of 2-methylnaphthalene

The oxidative metabolites of 2-methylnaphthalene (2-MN) were extracted from rat liver microsome suspensions. One monohydroxylated and three isomeric dihydrodiol metabolites of 2-MN were isolated and purified by HPLC. The metabolites were characterized by GC-MS together with 1H Fourier transform (1HFT) NMR. The identification of a 2-MN-monohydroxylated product as 2-hydroxymethylnaphthalene was confirmed by comparison of its HPLC retention time and NMR spectrum with that of a synthetic standard. The three isomeric dihydrodiol metabolites had different HPLC retention times, fragmentation patterns, ultraviolet, and 1H NMR spectra. GC-MS of the silylated dihydrodiols revealed the consistent presence of an ion peak at m/z 320, indicative of a disilylated dihydrodiol. Analysis of the 1H FT NMR spectra revealed the metabolites to be the 3,4-dihydrodiol, 5,6-dihydrodiol, and 7,8-dihydrodiol of 2-methylnaphthalene.