A 90-Day Inhalation Toxicity Study with Benomyl in Rats

A 90-Day Inhalation Toxiaty Study with Benomyl in Rats. WARHEIT,D. B., KELLY, D. P., CARAKOSTAS, M. C., AND SINGER, A. W. (1989).Fundam Appl Toxicol./ 12, 333-345. Benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate,CAS Registry No. 17804-35-2] is a fungicide and the possibilityfor inhalation exposure exists for field workers. To assessthe toxicity of benomyl, groups of 20 male and 20 female CDrats were exposed nose-only 6 hr a day, 5 days a week, to concentrationsof 0, 10, 50 or 200 mg/m³ of a benomyl atmosphere. At the midpoint(approximately 45 days on test) and at the end of the exposureperiod, blood and urine samples for clinical evaluation werecollected from 10 rats/group/sex, and these animals were sacrificedfor pathological examination. Similar evaluations were performadon all remaining rats at the end of the 90-day test period.After approximately 45 days on test, compoundrelated degenerationof the olfactory epithelium was observed in all males and in8 of 10 female rats exposed to 200 mg/m³ benomyl. Two male ratsexposed to 50 mg/m³ had similar, although less severe, areasof olfactory epithelial degeneration. After approximately 90days of exposure, the remaining 10 rats/group/sex were sacrificedand examined. Of these rats, all of the males and females exposedto 200 mg/m³ had olfactory degeneration, along with 3 malesexposed to 50 mg/m³ of benomyl. No other observed lesions wereinterpreted to have been caused by the benomyl exposure. Inaddition, male rats exposed to 200 mg/m³ benomyl had depressedmean body weights compared to controls and this finding correlatedwith a reduction in food consumption. Based on pathologicalobservations, 10 mg/m³ represents the no-observable-effect level(NOEL) for the male rats, and 50 mg/m³ is the NOEL for the femalerats.     

Effect of electrical stimulation on gastric electrical activity,motility and emptying

Abstract The aim was to measure the effect of gastric electrical stimulation on the frequency of canine antral pacesetter potentials (PPs), the strength of antral contractions, and the rate of gastric emptying while fasting, after feeding and with pentagastrin stimulation. Four conscious dogs with a stimulating electrode placed 10 cm proximal to the pylorus and recording electrodes and strain gauges placed 7, 5 and 3 cm proximal to the pylorus underwent myoelectric and strain gauge recordings while fasting, after feeding (250 ml 5% dextrose labelled with polyethylene glycol), and during pentagastrin infusion (0.5 μg kg^?1 min^?1) on four separate days. On each day, electrical stimulation was done using one of four stimulation frequencies (0, 6, 30 and 1200 stimuli per minute ***[s.p.m.]). Stimulation at 6 and 30 s.p.m. increased the fasting and fed PP frequency, whereas 1200 s.p.m. stimulation did not. Feeding decreased the maximum driven frequency, and pentagastrin increased it. Neither the motility index nor the gastric emptying rate were consistently changed by stimulation at any frequency. In conclusion, canine proximal antral stimulation at 6 and 30 s.p.m. sped PP frequency during fasting and after feeding, but stimulation over a wide range of frequencies had little effect on gastric contractions and emptying.     

Pathological variables determining the prognosis of non-Hodgkin''s lymphomas

The aim of the study was to assess the role of pathological grade, cell proliferation, ploidy, immunophenotype and site in determining the prognosis of non-Hodgkin's lymphomas. Of particular interest was the relative value of grades derived from the Kiel classification as opposed to the National Cancer Institute (NCI) working formulation. The study consisted of 181 cases, treated in a relatively uniform way over an 18-month period spanning 1986. Using life table analysis, both NCI working formulation grade and Kiel grade correlated strongly with survival. However, the differences between grades were entirely due to an excess of early deaths in the high-grade and intermediate-grade categories. In patients surviving greater than 0.1 years (37 days), phenotype, site, ploidy and cell proliferation had no effect on survival. There was no evidence that intermediate-grade tumours, when subdivided into Kiel low- and high-grade types, differed in survival from tumours graded as low- or high-grade by both methods. However, NCI working, formulation high-grade tumours, especially those with a high proliferation rate, formed a group with a very high likelihood of death within 0.1 years.