Cambium Destruction in Conifers Caused by Pinewood Nematodes

Percentage and rate of mortality in 2-4-year-old conifers depended upon the numbers of pinewood nematodes Bursaphelenchus xylophilus inoculated into their stems. In addition, percentage of conifer mortality was greater for spring inoculations when cambial activity was greater than for late summer and fall inoculations. Gross and histological examination of stems revealed destruction of the cambial layer, including fusiform and ray intitials and their derivatives. These data suggest that cambial and ray destruction causes tree death through blockage of tracheids by gas, oleoresin, or metabolites from dying ray tissues.     

New drugs in hypertension.

Clonidine, propranolol, bethanidine and debrisoquine effectively decrease blood pressure by suppressing renin secretion or interfering with function of the sympathetic nervous system. In man these compounds exert an antihypertensive effect within several hours or days and their duration of action is sufficient to permit administration twice or thrice daily. Clonidine and propranolol are especially useful if sexual dysfunction or postural hypotension is undesirable. Although bethanidine and debrisoquine may produce these adverse effects, they are beneficial in severe hypertension and produce fewer side effects than guanethidine. Clonidine frequently causes sedation, and rebound hypertension may occur with sudden cessation of therapy. Injudicious use of propranolol may provoke heart failure or asthma in susceptible individuals. The combination of a thiazide diuretic with propranolol and one of hydralazine, bethanidine and debrisoquine may be used to treat severe or complicated hypertension.     

Acid lipase-esterase (4-methylumbelliferyl oleate hydrolase) of white matter localized in oligodendrocyte cell bodies.

Abstract— The localization of an acid lipase-esterase which cleaves the fluorogenic substrate 4-methyl-umbelliferyl oleate at pH 5 was studied, because previous experiments has shown this activity to be reduced in the plaques of multiple sclerosis. In the human cerebellum, quantitative histochemical methods showed the activity to be relatively low in the molecular layer, compared to the granule cell layer; but the underlying white matter was the most active. In the human spinal cord, anterior horn cell bodies were richest in acid lipase, but white matter was, on a dry weight basis, as active as neuropil. Oligodendrocytes obtained in bulk from bovine white matter according to Poduslo & Norton (1972) had a specific activity up to 20 times greater than the crude myelin fraction. While it remains possible that in myelin the enzyme is in an inactive or inhibited state, the results indicate that the enzyme is localized in oligodendroglial cell bodies and suggest its use as a marker.     

Enumeration of enterotoxigenic Bacteroides fragilis in municipal sewage

Of 237 isolates of Bacteroides fragilis from sewage influent at the Bozeman, Mont., wastewater treatment plant, 22 (9.3%) were enterotoxigenic, as indicated by the ability to elicit fluid accumulation in the lamb ileal loop test. It appears that enterotoxigenic B. fragilis is endemic in the human population at a moderately high level.