Routine Passage Research Articles

Prolongada persistência do vírus da gripe em hamsters inoculados por vias parenterais e nasal

As experiências relatadas no presente trabalho visaram observar a persistência do vírus da gripe em hamsters inoculados pelas vias subcutânea, peritoneal e nasal. Usaram-se 53 hamsters na verificação da persistência do vírus nos seus organismos a qual atingiu até um ano e cinco meses, pelo menos, numa das séries de experiências. A outra parte do trabalho consistiu em verificar a passagem do vírus, em série, de hamster a hamster. Observamo-la até o máximo de nove vezes, o que foi excepcional, notando-se passagens, na série, com resultados negativos intercalados. Para esta última parte forma usados 91 hamsters, perfazendo o total de 144 em todas as experiências realizadas.

Anastomotic technic in esophageal atresia

66 _ W HAT IS THE BEST way to do the anastomosis?” When this question is cast among surgeons who treat esophageal atresia, brisk dialogue always follows. The question is important because esophageal anastomotic complications-leak and stricture-are technical failures, possibly avoidable, that cause death or disability in a significant number of cases. Today the infant born with esophageal atresia and tracheoesophageal fistula should have at least a 60 percent chance to live a normal life. Associated anomalies cause death in about 25 percent of the patients.2 Respiratory problems, especially in premature infants, also contribute to mortality. When the anastomosis leaks, the death and morbidity rates are high. Strictures cripple, may require many dilatations or a secondary anastomosis, and carry a significant mortality. Usually the gap between the esophageal segments is short enough to permit a comfortable primary anastomosis. When this is possible, the surgeon’s method of anastomosis, accuracy of suturing, and gentleness with tissues determine how well the reconstructed esophagus will work. Imperfect technic increases the chance of anastomotic complication. There are three types of anastomoses used in esophageal atresia. In a survey of the members of the Surgical Section of the American Academy of Pediatrics,’ the single layer end-to-end anastomosis was most popular. It also had the highest incidence of leaks, the highest mortality from leaks and a substantial incidence of strictures. Unquestionably it is the easiest anastomosis to perform. The Haight telescopic anastomosisl was used almost as often as the single layer end-to-end. It had the lowest incidence of leaks, the lowest mortality from leaks, but the highest stricture rate. It is more difficult to perform. The two layer end-to-end anastomosis was least popular in the survey. It ranked between the single layer end-to-end and the Haight anastomoses in number of leaks and survival from leaks, and was comparable to the single lnver in the number of strictures. It is the most difficult to perform. Tables 1 and 2 are taken from the survey.” Potts suggested refinements of the two layer end-to-end anastomosis.” His technic was applied to 102 patients who had esophageal atresia with distal tracheoesophageal fistula, 75 from the Children’s Memorial Hospital, Chicago4 and 27 personallv treated bv the author. Four percent leaked; significant i stricture formation was 8 percent. A significant stricture is one that is symptomatic alld requires more dilatation than the routine passage of soft catheters performed in most cases.

Active immunization against Plasmodium berghei malaria in mice.

Summary It has been possible to achieve active immunity against Plasmodium berghei malaria in mice without a primary patent infection. This was accomplished by vaccination with a strain of P. berghei which had lost its infectivity for mice, though not for rats, following a number of passages in tissue culture containing the serum of young male hamsters. The immunity is of the sterile type, and not due to premunition. It was shown that latency in mice denotes a partial breakdown or imperfect development of immunity rather than degree of protection. Immunity takes from 2–3 months to develop fully, and during the pre-immune period mice are particularly sensitive to reinfection. Immunity, once established, persists at a high level for many months. The modified strain is believed to present more antigenic groupings of the type which can effectively stimulate protective antibody production. It appears that trophozoites capable of stimulating immune responses are screened out of the circulation. The trophozoites, which are not screened out and appear in the peripheral blood stream, are not believed to contribute greatly to the stimulation of immunity, even though immunity appears directed against erythrocytic forms. The modified strain reverts to its original character during routine blood passage every 2 weeks in rats over a period of 46 weeks. Different characteristics reverted at different rates. It is concluded that invasiveness, virulence, and ability to stimulate an effective immune response are separate and independent characteristics of the parasite.

AN UNIDENTIFIED VIRUS WHICH CAUSES THE RAPID PRODUCTION OF TUMOURS IN MICE.

IN the course of routine passage of Moloney's leukaemogenic virus (MLV) plasma was collected from a leukaemic rat (Chester Beatty Institute outbred albino strain) which had been inoculated with MLV-containing mouse plasma when new-born. After storage at −70°C for three months the rat plasma was diluted 1 in 30 with Hanks's saline and passed through a ‘Selas 02’ filter, tested and found impervious to Esch. coli. The filtrate was injected into 15 new-born BALB/c mice, as a test of potency. Only 6 survived to weaning. On the 32nd day 5 had tumours at or near the injection site, and all had grossly enlarged spleens. Usually mice inoculated with MLV remain symptomless until they show the characteristic signs of leukaemia after 8 weeks.

Studies of leukemia L2C in guinea pigs.

1. Leukemia L2C is transmissible, in routine passages, with high-speed centrifuged leukemic spleen extracts. The extracts were prepared from leukemic spleen cells which had been disrupted by several methods. 2. Leukemia L2C is transmissible, in routine passages, with highspeed centrifuged leukemic plasma which had been harvested at early or late stages of the disease. 3. Leukemia L2C has been transmitted, in repeated experiments, with leukemic spleen extract, leukemic brain extract, or leukemic serum after these materials had been passed through bacteria-tight filters of various types. 4. Susceptibility to leukemia L2C appears to be essentially limited to inbred strain No. 2 guinea pigs or to F1 hybrids born from crossmating susceptible with resistant guinea pigs. These is some evidence to suggest that susceptibility of strain No. 2 guinea pigs to leukemia L2C is inherited as a dominant characteristic. 5. The leukemogenic agent is capable of passing the placenta in the leukemic animal. Embryos of leukemic mothers may appear normal, but their tissues could be shown to harbor the disease-transmitting agent. 6. When injected intraperitoneally into susceptible guinea pigs, the leukemogenic agent appeared in the plasma of the animal for the first time on the 4th day and was thereafter regularly present in all subsequent plasma samples. Whole blood transmitted leukemia at the 24 h and 48 h intervals, but not at the 72 h interval. Beginning with the 4th day again, all subsequent whole blood samples transmitted the disease. In the resistant animal, the leukemogenic agent was sporadically present during the first five days in plasma or in whole blood. Samples taken after that time no longer transmitted leukemia.

Rocky Mountain Spotted Fever: A Note on Some Aspects of Its Epidemiology

In spite of several published statements to the contrary (1), it has long been the popular conception that Rocky Mountain spotted fever is a more highly virulent, and, therefore, a more fatal disease in the West than in the East. Up to comparatively recently, reported observations in the laboratory lent support to this belief because the strains of virus isolated and reported in the West were more pathogenic for guinea pigs than the strains isolated in the East. For the past few years strains of the virus of Rocky Mountain spotted fever have been isolated in guinea pigs at the National Institute of Health in Washington, D. C., upon eveiy presenting occasion along the Atlantic seaboard. These strains have all been studied during their routine passage in guinea pigs, some for as long as a year, others for not such an extended period. These isolated strains were all similar; none of them produced scrotal lesions in male guinea pigs with any degree of consistency; they all had rather prolonged incubation periods; and their fatality rates were considerably lower than our passage strain of virus which has been isolated in Montana. During the summer of 1939, however, a different strain of spotted fever virus was recovered (2). This strain was from a young man hospitalized with Rocky Mountain spotted fever at the Gallinger Municipal Hospital in Washington, D. C. The patient had been berry picking across the Potomac River in Virginia, where ticks were abundant. He was not critically ill, but the strain isolated from his blood was extremely virulent for guinea pigs. The fatality rates in these animals on this, the W strain, are as high as those for our passage virus isolated in the Bitterroot Valley of Montana, being around 80 percent for each strain. The typical scrotal lesions associated with a highly pathogenic strain of Rocky Mountain spotted fever are consistently present. The incubation period for this strain is shorter than for any of the other strains of spotted fever isolated in the East. More recently Brigham and Watt (3) reported the isolation of two highly virulent strains from ticks, D. variabilis, in Georgia. During the summer of 1940 the occasion arose to isolate a strain of spotted fever from a typical case of the disease in a Denver, Colo., hospital. This patient had acquired a tick while fishing near Lander, Wyo., which is located in the center of the so-called D. andersoni territory. The L strain (4) of spotted fever, from this patient, is extremely mild for guinea pigs, a fatality rate of 4.4 percent being observed with this strain, lower than any other strain of spotted fever