Pathogenesis of Enterococcal Spondylitis Caused by Enterococcus cecorum in Broiler Chickens.

Enterococcal spondylitis (ES) is a disease of commercial broiler chickens, with a worldwide distribution. Symmetrical hind limb paralysis typical of ES results from infection of the free thoracic vertebra (FTV) by pathogenic strains of Enterococcus cecorum . To determine the pathogenesis of ES, birds with natural and experimental ES were studied over time. In natural disease, case birds (n = 150) from an affected farm and control birds (n = 100) from an unaffected farm were evaluated at weeks 1-6. In control birds, intestinal colonization by E. cecorum began at week 3. In case birds, E. cecorum was detected in intestine and spleen at week 1, followed by infection of the FTV beginning at week 3. E. cecorum isolates recovered from intestine, spleen, and FTV of case birds had matching genotypes, confirming that intestinal colonization with pathogenic strains precedes bacteremia and infection of the FTV. Clinical intestinal disease was not required for E. cecorum bacteremia. In 1- to 3-week-old case birds, pathogenic E. cecorum was observed within osteochondrosis dissecans (OCD) lesions in the FTV. To determine whether OCD of the FTV was a risk factor for ES, 214 birds were orally infected with E. cecorum, and the FTV was evaluated histologically at weeks 1-7. Birds without cartilage clefts of OCD in the FTV did not develop ES; while birds with OCD scores ≥3 were susceptible to lesion development. These findings suggest that intestinal colonization, bacteremia, and OCD of the FTV in early life are crucial to the pathogenesis of ES.

Delays in thrombolytic therapy for acute myocardial infarction: association with mode of transportation to the hospital, age, sex, and race.

BACKGROUND: Although increased myocardial salvage and reduced mortality are associated with timely thrombolytic therapy for acute myocardial infarction, some patients still experience delays in treatment. OBJECTIVES: To examine treatment times in patients with acute myocardial infarction treated with thrombolytic therapy and to determine whether delays in treatment are associated with mode of transportation to the hospital, age, sex, or race. METHODS: Medical records of 176 patients with acute myocardial infarction treated with thrombolytic therapy at a community hospital were reviewed and analyzed retrospectively. RESULTS: Median times for the interval between arrival at the hospital and acquisition of a diagnostic electrocardiogram (door-to-electrocardiography time) and the interval between arrival and start of thrombolytic therapy (door-to-drug time) were 6 minutes and 34 minutes, respectively. However, 76.1% of the patients met the recommendation of the American College of Cardiology/American Heart Association of door-to-electrocardiography time of 10 minutes, and 47.2% met the recommendation of door-to-drug time of 30 minutes or less. Door-to-drug times did not differ significantly according to race or mode of transportation to the hospital. Door-to-electrocardiography and electrocardiography-to-drug times were significantly longer for older patients than for younger patients (P = .005 and P < .001, respectively), and electrocardiography-to-drug times were significantly longer for females than for males (P = .01). CONCLUSIONS: With increased emphasis on recognition and rapid treatment of patients with acute myocardial infarction at highest risk for delays in treatment, that is, women and the elderly, benefits of thrombolytic therapy might be maximized.

SOME OBSERVATIONS ON THE VERTICAL MIGRATION OFDINOFLAGELLATES (1) (2).

The technique of measuring chlorophyll concentration in vivo by fluorometric analysis has been adapted to studying the diurnal migration of dino-flagellates in the sea and also in a deep tank (3 m in diameter by 10 m deep). The downward migration of Ceratium furca was followed during a bloom off the California coast. The main band of cells migrated from the upper 2 m to a depth of 5 m about 2 hr after sunset, and was dispersed between 5 and 16 m 4.5 hr after sunset. Cultures of Gonyaulax polyedra and Cachonina niei both migrated to the surface of the deep lank during illumination and migrated downward during darkness at a rate of 1-2 mjhr. The downward migration was observed to begin before the light was turned off, indicating that migration is correlated with a cellular periodicity which is to some extent independent of the light regime. Further evidence for such a periodicity was afforded by observations that C. niei start to migrate up in the water column before start of the light period. Nitrogen-limited cells of G. polyedra showed no diurnal migration, but within 1 day after addition of a nitrogen source they recovered their full migratory ability. Cells of C. niei, however, continued to migrate during 5 days of N-starvation, although they did not concentrate in the upper 1/2 m as did the control cells.

HETEROTROPHY OF FOUR MARINE PHYTOPLANKTERS AT LOW SUBSTRATE CONCENTRATIONS(1).

Three pelagic marine phytoplankters, Coccolithus huxleyi, Skeletonema costatum, and Thalassiosira ro-tula, and a facultative heterotroph, Cyclotella cryp-tica, have been exposed to three organic substrates, viz, glucose, acetate, and glutamate, at low concentrations (organic carbon 0.25 mg/liter). Experiments were performed in the dark and light and the net assimilation of substrate was measured by using radiocarbon. The dark uptake of carbon dioxide was also determined, together with photosynthesis at near optimum light intensity. The expected heterotrophy was detected with Cyclotella cryptica. Thalassiosira rotula was found to assimilate glutamate at an appreciable rate. In all cases, however, the short-term uptake of carbon dioxide in the dark was the greatest assimilation rate measured. Values are discussed in relation to their ecological significance and it is concluded that heterotrophic survival of these and probably most other algae in the open ocean xuould be impossible unless they were in contact with a high concentration of substrate in the form of particulate matter.