THE EFFECT OF INJECTIONS OF HEMOLYTIC STREPTOCOCCI ON SUSCEPTIBLE AND INSUSCEPTIBLE ANIMALS

ROENTGEN RAY INTOXICATION : I. BACTERIAL INVASION OF THE BLOOD STREAM AS INFLUENCED BY X-RAY DESTRUCTION OF THE MUCOSAL EPITHELIUM OF THE SMALL INTESTINE

The x-ray has a specific effect upon the epithelium lining the crypts and covering the villi of the small intestine. A suitable dose of x-ray will destroy this epithelium in large measure, leaving empty crypts and naked villi exposed to swarms of bacteria in the intestine. Subsequently one does not observe an overwhelming invasion of the tissues, lymph, and blood by intestinal bacteria. It seems obvious therefore that the intestinal epithelium is not the all important barrier which protects the tissues from invasion by intestinal bacteria.

The Examination of the Tissues and Some Observations of the Blood Platelets of Rabbits at Intervals of Five Minutes, and Later, after Intravenous Inoculations of Staphylococcus aureus and Indian Ink

1. The tissue reactions in rabbits from intravenous injections of live and dead Staphylococcus aureus and massive doses of indian ink and colloidal silver have been studied.

2. Any particles injected into the circulation cause the accumulation of polymorphs in the lung capillaries.

3. Inert colloidal particles such as indian ink are clumped in the capillaries of the lungs, liver, spleen and kidneys, and are phagocytosed by the endothelial cells.

4. Staphylococci (S. aureus), live or dead, are nearly all held up in the lungs, where they are actively phagocytosed by the polymorphs within 5 minutes of an intravenous injection.

5. Subsequently the cocci are distributed to the other organs, where phagocytosis continues mainly by polymorphs, but in the liver also by the Kupfer cells.

6. Special attention is drawn to the localisation of the cocci in certain areas in the kidneys.

7. Platelet counting on animals injected with various substances showed that there is an agglomeration of the particles with the platelets, which are consequently removed from the circulation.

8. In the case of the inert particles the platelets are then restored to the circulation. With organisms (S. aureus) some of the platelets appear to be completely removed from the blood together with the bacteria.

CONDITIONS INFLUENCING THE DISAPPEARANCE OF LIVING BACTERIA FROM THE BLOOD STREAM

1. The simultaneous intravenous injection into normal and actively immunized rabbits of equal quantities of living staphylococci or paratyphoid bacilli is followed by a distinctly accelerated rate of removal of the bacteria from the blood streams of the immune animals. 2. This altered reactivity is due essentially to specific active immunization. 3. The bacteria pass rapidly through the capillary bed of the lungs, extracellularly and dispersed for the most part, and become generalized through the blood stream. 4. The bacteria are quickly removed from the circulating blood in the immune animals and less rapidly in the normal ones, by various organs, particularly the liver and spleen, where they accumulate in enormous numbers, become adherent to the lining membrane of the sinusoids of the liver and apparently to the macrophages of the spleen and are phagocytosed by the macrophages and leucocytes in these organs. 5. Associated with this effect are morphological changes in the bacteria as shown by swelling, loss of staining power and evidences of increased cohesiveness and decreased viscosity, these changes being apparent as early as 2 minutes after their intravenous injection. 6. Inasmuch as these changes are not seen to a marked degree within the lungs or other organs, they are probably the result of a local antigen-antibody reaction of a bacteriotropic type in the two organs generally considered to be most actively concerned with the production of immune bodies. 7. By means of this accelerated bacteriotropic effect in the actively immunized animals, phagocytosis is facilitated and intracellular digestion of the bacteria is enhanced.

QUANTITATIVE DISTRIBUTION OF PARTICULATE MATERIAL (MANGANESE DIOXIDE) ADMINISTERED INTRAVENOUSLY TO THE DOG, RABBIT, GUINEA PIG, RAT, CHICKEN, AND TURTLE

The distribution of manganese dioxide particles 1 hour following intravenous injection in cats, dogs, rabbits, guinea pigs, rats, chickens, and turtles is described. This distribution is remarkably constant for all the animals tested, except the cat, in which the injected material is practically equally divided between the lungs and liver. In the other animals the liver performs the main share of the work, and in the cat it has been shown that the liver after 12 hours accumulates the manganese which was formerly deposited in the lungs. The results are in harmony with experiments in which bacterial suspensions are employed for injection and confirm the suggestion previously made (2) that in the first handling of foreign particulate material the animal behaves similarly whether protein or inorganic injections are used.

The splanchnic removal in rabbits during fatal bacteremias of the circulating organisms and of superimposed non-pathogenic bacteria

1. By a method of hepatic venous catheterization previously described, comparative data have been obtained concerning the removal of pneumococci from the splanchnic circulating blood of the intact rabbit in bacteriemias secondary to a dermal infection and in bacteriemias induced by a continuous infusion of organisms into the blood stream. The average splanchnic removal in secondary pneumococcal bacteriemias was 8 ± 14 per cent (S.D.), in induced bacteriemias 9 ± 15 per cent (S.D.). 2. Similar data were obtained in induced M. aureus bacteriemias in normal rabbits and in induced M. aureus bacteriemias superimposed upon pneumococcal bacteriemias secondary to dermal infection. The average splanchnic removal of M. aureus in normal rabbits was 62 ± 20 per cent (S.D.). The splanchnic removal of M. aureus in rabbits with a simultaneous pneumococcal bacteriemia of infection was of the same order of magnitude as in normal rabbits. 3. The efficiency of the mechanism of splanchnic removal for a given organism is an important factor in the establishment and maintenance of a bacteriemia. Present evidence indicates that the maintenance of a bacteriemia requires a constant introduction into the blood stream of organisms from some source. 4. Pneumococci do not acquire a resistance to removal from the splanchnic circulating blood during the course of fatal infection in rabbits. 5. No final exhaustion of the mechanism of splanchnic removal can be demonstrated in fatal pneumococcal bacteriemias in rabbits.

Pulmonary intravascular macrophages in domestic animal species: review of structural and functional properties

In dogs, laboratory animals, and man, the clearance of bacteria and particulates from blood occurs predominantly in hepatic Kupffer cells and splenic macrophages. In contrast, removal of blood-borne particulates in calves, sheep, goats, cats, and pigs occurs predominantly in pulmonary intravascular macrophages (PIMs). Review of recent studies indicates that PIMs are a resident cell population, junctionally adherent to the capillary endothelium of lungs and morphologically similar to hepatic Kupffer cells. PIMs are a pulmonary constituent of the mononuclear phagocyte system with respect to secretory, endocytic, and functional properties. Differentiated PIMs are rare in newborn pigs, and the majority of cells closely apposed to capillary endothelium consists of monocytes, which are occasionally in mitosis. In 7-day-old and older pigs, most cells apposed to capillary endothelium have characteristics of differentiated PIMs. This suggests a monocytic origin of PIMs in pigs. Perinatal colonization of lung capillaries by monocytes and their subsequent differentiation into PIMs represent a component of postnatal lung development. Estimates of relative PIM numbers in ovine and porcine lung parenchyma suggest cell densities similar to that of rat hepatic Kupffer cells. Apart from phagocytic properties, PIMs participate in the removal and disintegration of aged and impaired blood cells. After phagocytic stimulation, isolated PIMs secrete oxygen radicals, which are essential for microbicidal function. Similarly, by secreting bioactive lipids, stimulated PIMs may contribute to regulation of pulmonary hemodynamics. After receiving minute amounts of bacterial endotoxin, pulmonary injury is pronounced in sheep, calves, pigs, and cats, but not in laboratory animals and dogs. This presumably is related to the secretion of bioactive lipids by PIMs.

Postnatal colonization of porcine lung capillaries by intravascular macrophages: an ultrastructural, morphometric analysis

Lungs of newborn and of 7- and 30-day-old pigs were fixed at total capacity by a standardized procedure. Stereologic morphometry was applied to random ultrathin sections of parenchyma. Relative volume density, absolute volume, and capillary surface coverage of intravascular macrophages as well as parameters of relative morphometric diffusion capacity of lungs were assessed. Intravascular macrophages occupied up to 25% of capillary volume in 30-day-old pigs compared with 6% in newborn pigs; this was a 14-fold increase of absolute volume. In 30-day-old pigs, 16% of capillary surface was covered with closely adherent intravascular macrophages in contrast to only 2% in newborn pigs. Determinators of morphometric diffusion capacity were similar in all pigs. Greater thickness of the arithmetic and harmonic mean air-blood tissue barrier in 30-day-old pigs (with included thickness of intravascular macrophages) compared with air-blood tissue barriers (without intravascular macrophages) was not statistically significant. The relative difference of arithmetic mean was larger than the difference of harmonic mean, and reflected preferential adherence of intravascular macrophages to the thick portion of the air-blood tissue barrier. Our findings confirm morphologic observations of perinatal colonization of the porcine lung by monocytes that replicate and differentiate into large, highly phagocytic, resident, intravascular macrophages. Preferential adherence to sites where basal laminae of capillary endothelium and alveolar epithelium were separated by interstitium may explain the minimal morphometric impact of intravascular macrophages on the air-blood tissue barrier thickness. This location would be expected to have less effect on gas diffusion than location of intravascular macrophages on the thin side of the air-blood barrier.

Studies on bacteriemia. I. Mechanisms relating to the persistence of bacteriemia in rabbits following the intravenous injection of staphylococci

During the course of studies on the characteristics of experimental bacteriemia, staphylococci were swiftly cleared from the blood stream of rabbits during the initial 10 to 15 minutes following intravenous injection of microorganisms. A subsequent abrupt decline in the rate of clearance ensued, resulting in a low grade bacteriemia which was demonstrable for many hours. The experiments reported have indicated that this strain of staphylococcus is rapidly phagocyted within the vascular system of rabbits, and that viable staphylococci circulate within the cytoplasm of polymorphonuclear leukocytes. The removal mechanisms contained within the liver and spleen appear to preferentially trap circulating extracellular staphylococci. When most of the circulating staphylococci are contained within leukocytes, splanchnic removal declines or virtually ceases. These observations suggest that viable, intracellular microorganisms are responsible for the persistence of staphylococcal bacteriemia in rabbits following the phase of rapid removal from the blood stream.

BLOOD CHEMICAL CHANGES IN EXPERIMENTAL STREPTOCOCCUS SEPTICEMIA

The following changes have been found to occur in rabbits given fatal intravenous doses of Streptococcus hemolyticus: The blood sugar concentration drops at a constant rate throughout the disease, but does not reach a condition of hypoglycemia. Glycogen is present in the liver at death. The CO(2) capacity is lowered markedly at first, then returns to a somewhat higher level, at which it continues until the terminal stage of the disease, when the acidosis becomes very marked. Inorganic phosphorus is markedly increased in concentration at the terminus of the disease. This increase is greater in animals showing an acute course than in those in which the disease is of the fulminating type. Calcium also shows terminal changes, decreases occurring in both groups. In the acutely infected rabbits the decrease is less than in the fulminating group, although in both a pathological level is reached. Non-protein nitrogen and creatinine are greatly increased in the terminal stages, in both groups of animals. It is suggested that these observations can be explained on the assumption of a large amount of acid production by the streptococcus in vivo.