Solubility fo fibrin clots in monochloroacetic acid. A reflection of serum pepsinogen levels

Fibrin clots formed from normal plasma dissolve readily in 1% monochloroacetic acid at 37 C. However, if the clots are washed thoroughly before the acid is added, they are no longer soluble. The agent present in the serum which causes dissolution of the fibrin clot was isolated and identified as pepsinogen. Because of the low pH of monochloroacetic acid the pepsinogen is activated and the clots are digested, simulating the dispersion of a fibrin clot which occurs in the absence of fibrin-stabilizing factor (factor XIII). Because of its higher pH, urea will not activate pepsinogen and is therefore a better agent to screen factor XIII deficiencies.

Inhibited development in Ostertagia ostertagi infections--a diapause phenomenon in a nematode

Experiments are described which show that in a recently isolated field strain of the cattle nematode, Ostertagia ostertagi, the primary stimulus to the induction of inhibited development at the early fourth larval stage (EL4) in the host is chilling of the infective larvae (L3). Thus exposure of L3 to a temperature of 4 °C for 8 weeks prior to their oral administration to calves resulted in a mean of 66% of the established worm burden becoming inhibited at the EL4 stage. This provides an explanation for the seasonal occurrence in Britain of inhibited EL4 stages of O. ostertagi in cattle during the cold climate of late autumn and winter.

If the L3 stages were exposed to chilling for a prolonged period (> 19 weeks), prior to infection of calves, then the prevalence of inhibited EL4 stages amongst the worms established declined. After 33 weeks chilling the worm population consisted almost entirely of adults and only 2% inhibited EL4 stages. This suggested that a selective mortality of inhibition prone L3 was taking place and explained why under natural grazing conditions inhibition prone L3 were not available on the pasture in spring.

The duration of inhibition at the EL4 stage in calves infected with chilled L3 was consistently between 16 and 18 weeks and maturation of the majority of the inhibited larvae occurred spontaneously after such a period and irrespective of season. This period is equivalent to the duration of a normal winter in Britain when conditions unsuitable for the free living development of O. ostertagi larvae prevail.

The induction of inhibition by the environmental stimulus of chilling, the fixed period for the duration of inhibition within the host and the spontaneous maturation of the inhibited larvae are characteristic of a true diapause.

Effects on abomasal function of Ostertagia circumcincta infections in sheep

Sheep in which abomasal fundic pouches had been made were infected with Ostertagia circumcincta (150000 larvae in one sheep, 100000 in three sheep). Subsequently studies were made on pouch secretion, food intake, plasma pepsinogens and abomasal pouch secretory responses when the sheep first ate. A functional abomasal lesion was apparent within 4 days of infection judged by the changes in plasma pepsinogen levels and the sodium concentrations of abomasal contents. Whereas the secretory activity of the abomasal fundic pouches (never exposed to parasites) was maintained or increased, the pH and sodium concentration of contents taken from the infected part of the abomasum were indicative of either a failure to secrete or of a permeability reabsorptive lesion. Ultrastructural studies demonstrated that parietal cells of the pouches had the appearance of cells subjected to strong secretory stimuli, but those of infected abomasa were similar to cells of gastric mucosa subjected to agents suppressing secretion. Factors which might operate, on the one hand, to stimulate secretion from separated fundic abomasal pouches, and on the other to inhibit or modify the secretory activity of the fundic mucosa of the infected abomasa, are discussed.

Hematological and blood chemical data in pigs fed on fine, medium and coarse ground dry grain

Blood was collected the day before slaughter from pigs fed fine, medium or coarse ground grain and examined in accordance with Tables 1–3. Of the 15 pigs (group 1) on the finest meal all except one developed parakeratotic or erosive changes (Figs. 1–5) in the pars oesophagea of the stomach. In group 2 (medium ground) the corresponding number was seven out of 18. No pathological alterations could be detected in the stomach of the pigs on coarse grain.

Statistically significant or almost significant differences were obtained between the groups for hemoglobin, hematocrit, number of erythrocytes, urea-N and pepsinogen. A much wider range was observed in the γ-globulins of the group on fine grain than in the other two groups. The differences in proteins were, however, not significant. To see whether the observed differences between the groups were related to the gastric pathological alterations or to the feed, a comparison was made between pigs with and without pathological changes (Table 3). There were still significant, though smaller, differences in the hemoglobin and hematocrit values. A higher level of significance was only obtained for pepsinogen.