Further experimental studies of Pneumostrongylus tenuis in cervids

Two young wapiti (Cervus canadensis nelsoni) and a female mule deer fawn (Odocoileus hemionus hemionus) were infected experimentally with Pneumostrongylus tenuis from white-tailed deer (Odocoileus virginianus borealis). The male wapiti showed only slight clinical signs after infection, and first-stage larvae appeared in its faeces 92 days later. The female wapiti showed severe neurological signs that terminated in general paralysis on the 54th day. The mule deer showed severe neurologic signs and died of paralysis on the 62nd day. Numerous worms were found in the subdural space and neural parenchyma, especially in the dorsal horns of grey matter, of the female wapiti and the mule deer. Traumatic damage in the dorsal horns was extensive, especially in the wapiti. Histopathologic findings were similar to those reported earlier in moose calves (Alces americana americana) infected with P. tenuis. Study of worms recovered from experimentally infected cervids indicates that P. tenuis develops similarity in white-tailed deer, moose, wapiti, and mule deer although in the first species it causes little damage to the central nervous system. The possibility that P. tenuis could become established in wapiti introduced into eastern North America is noted.

Experimental cerebrospinal nematodiasis (Pneumostrongylus tenuis) in sheep

Six lambs were each infected experimentally with 50–1000 infective larvae of Pneumostrongylus tenuis. Three animals displayed neurologic signs. Lesions and dead or living worms were found in the central nervous system of all infected lambs. It is concluded, however, that sheep have a good natural resistance to infection and that P. tenuis will not mature in them. Before P. tenuis is diagnosed in naturally infected sheep it would be advisable to establish whether the sheep have been in contact with white-tailed deer, the normal host.

The transmission of Pneumostrongylus tenuis to guinea pigs

Pneumostrongylus tenuis developed partially in the central nervous system of infected guinea pigs, some of which developed severe neurologic signs, especially posterior paralysis. Damage to the central nervous system was noted in various regions of the brain and in the white matter of the spinal cord. There was no evidence that the worms will mature in guinea pigs and the number of worms recovered from infected animals was small. P. tenuis behaves in a rodent in the same way as in the normal ruminant host, in contrast to lungworms of carnivores in which the infective larvae become quiescent and encapsulated in the liver of small mammals without loss of infectivity. It is suggested that this ability to retain infectivity after encapsulation is not a general attribute of lungworms or other parasitic nematodes, but has had a long evolutionary history. It should clearly be distinguished from visceral larval migrans which it superficially resembles. Hypotheses to account for the origin of heteroxenous life cycles of nematodes of vertebrates are contrasted as they apply to the Metastrongyloidea.

Survey of serologic evidence for syphilis among the Masai of Tanzania

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Osmotic Pressure Influence in Germination Tests for Antibiosis

A common test for the presence of toxic organic substances in plant tissues, and therefore of the potential role of antibiosis (specifically allelopathy) in native plant cozmmunities, has been to apply a water extract of the tissues in germination tests of cultivated annuals. The observed osmotic pressure of the extracts can be high, and sucrose solutions of similar osmotic pressure result in a depression of germnination and early development. Thus in the aforementioned type of test, extracts must be diluted to an osmotic pressure no greater than 0.5 atmopheres.

The determination by quantitative histochemistry of the effect of phenothiazines on brain cytochrome C oxidase activity

The Burstone method (1961) for the histochemical demonstration of cytochrome c oxidase was quantified and applied to the study of the effects of chlorpromazine and trifluoperazine on the activity of this enzyme in rat forebrain, hypothalamus, cerebellum and pons-medulla. Fresh frozen, 10-µ-thick sections from rat brain were incubated in a buffered medium containing p-aminodiphenylamine and 8-amino-1,2,3,4-tetrahydroquinoline. The colored oxidized product of cytochrome c oxidase activity was extracted with ethanol and the optical density determined. In one series of experiments the phenothiazine was added to the incubating medium. For 50% inhibition of cytochrome c oxidase the following average tissue concentrations of chlorpromazine were required: cerebellum, 20 mM; forebrain, 27 mM; pons-medulla, 42 mM. Trifluoperazine was required in higher concentrations: cerebellum, 38 mM; forebrain, 47 mM; ponsmedulla, greater than 70 mM. In another series the phenothiazine was given intraperitoneally, 100-200 mg/kg. No significant inhibition of the enzyme was noted. The tissue concentration in vivo of the drug was well below the tissue concentration in vitro associated with minimum enzyme inhibitions.

Impaction of cardiac catheter in coronary vein

A complication of right heart catheterization is described in which the tip of the catheter became impacted in a vein connecting to the coronary sinus, requiring thoracotomy and removal under direct vision. This occurred in a 2-year-old patient with an anomalous inferior vena cava with azygos continuation, and it is suggested that this anomalous course may well have contributed to the development of this complication.