Cyst Production Research Articles

Studies on Entamoeba Histolytica

Summary and Conclusions 1. Using a fluid medium consisting of buffered phosphate in sodium chloride solution, liver fluid, and rice starch as an encystment medium, a study has been made of the relation of hydrogen-ion concentration of the medium to the encystment of E. histolytica in culture. 2. It has been found that the optimum total salt concentration in the medium for growth and encystation of E. histolytica is M/30 phosphate and 0.4 per cent sodium chloride. 3. Utilizing the optimum phosphate and sodium chloride concentration, the optimum pH value of the medium for cyst production was determined. It was found that when the initial pH value of the medium was 6.8 to 7.0, and the pH values after 24, 36 and 48 hours of incubation were 6.7–6.9, 6.8–7.0 and 6.9–7.2 respectively, rich encystation was observed. The maintenance of a favorable pH range throughout the period of incubation is believed to depend not only on the initial pH value but also on the accompanying bacterial flora. 4. It appears under the condition of these experiments that in order to have a rich encystment, even in a medium of favorable pH value, the rate of growth of the amoebae must also be greatly accelerated. When abundant growth is reached, the majority will excyst. 5. Not all strains of amoebae give a rich cyst yield even when these two requirements are fulfilled. It is believed that all strains of amoebae have a tendency to encyst under favorable conditions, but much of this tendency may be lost on prolonged cultivation in a medium. 6. The liver extract favors the growth of amoebae, but the amount of liver extract required to make up the medium, within the ratio of 1:60 to 1:160 to that of the phosphate-salt solution, affected the encystment only through its effect on the pH values. 7. Amounts of encystment medium of 15–20 ml. seem to maintain a favorable pH value range better than smaller or larger amounts, and therefore induce better encystment. 8. On the basis of this study, a medium is proposed for encystment of E. histolytica in culture. It is composed of 15–20 ml. of M/30 phosphate buffered at pH 7.6, ⅕–⅙ ml. of liver extract fluid, and 2–3 loopfuls of rice starch. With a strain known to encyst in culture and having a good accompanying bacterial flora, rich encystment is to be expected in this medium. To assure good results, the initial pH of the medium prepared should be tested and should not be lower than 6.8. If the medium is to be stored for some time before use, the phosphate-salt solution should be buffered at pH 7.8, as the pH value decreases on storage.

Solitary Cysts of the Kidney

THE causative factors involved in the production of solitary cysts of the kidney have been subject to considerable discussion for a long period of time. Cysts of the kidney in general have long been recognized by anatomists. In fact, they were described by Fabry of Hilden who died in 1624, and have been studied by other distinguished anatomists, including Willis and Morgagni. However, the exact etiology has never been satisfactorily determined. Etiologic Theories.—One etiologic theory explains the development of the cyst on the basis of a mechanical blockage of the collecting tubules, with subsequent retrodilatation. Other authors contend that it is due to a retention incident to interstitial nephritis. A third theory states that the cyst may be caused by a persistence of the “anlagen or rudiments of uriniferous tubules in the vesicular phase of development and their later expansion.” Still another hypothesis is that failure of the S-shaped anlagen of uriniferous tubules to unite with the straight collecting ducts may be the causative factor. The failure of the uriniferous tubules to join the collecting ducts of higher orders (later generations) after having become detached from such ducts of a lower order is also considered as involved in the production of cysts. The belated appearance of disconnected cavities in a uriniferous tubule which had remained solid during its formation has also been presented as an instrumental factor. Finally, the secondary compression of collecting or secretory tubules caused by local inflammatory processes, as congenital syphilis, is considered by others to offer a satisfactory explanation for the production of cysts. Recently, Hepler (1) has experimentally produced such cysts in the kidney of a rabbit by fulgurating a papilla and ligating the artery which supplied the same pyramid. He thus produced an obstruction to urinary secretion and an anemia of the obstructed secretory tissue. Symptomatology.—In many cases, the cyst is relatively small and does not interfere with renal function, and hence produces no symptoms. In such instances, the finding of the cyst is coincidental at necropsy. When the cyst enlarges it may attain sufficient size to exert pressure on adjacent organs, or the presence of a mass may be noted by the patient. Occasionally a dull dragging or aching in the loin or hypochondrium may be experienced. As a general rule, urinary symptoms do not predominate, although in rare instances hematuria has been reported. Diagnosis.—As stated previously, the small cysts are asymptomatic; no symptoms referable to the urinary tract occur and their presence is not suspected. The larger cysts are usually confused with hydronephrosis, polycystic kidney, ovarian cysts, and occasionally renal neoplasm. The roentgenogram may show the outline of the cyst, especially if it arises from the lower pole of the kidney and has attained moderate size.

THE ETIOLOGY AND PATHOLOGY OF CYSTS OF THE PANCREAS

In a previous communication 1 we reported on a clinical study of forty-seven cases of pancreatic cysts treated surgically at the Mayo Clinic in the last ten years. In this paper we shall consider: (1) the pathogenesis of cysts of the pancreas, (2) our classification and (3) the pathologic manifestations of such cysts. As a basis for our study, we reviewed the literature, the records at the clinic and the operative and necropsy material obtained in eighty-eight cases of cysts of the pancreas treated surgically, as well as that in twenty cases in which such cysts were discovered incidentally at necropsy. Comparatively little experimental work has been done on the production of cysts in the pancreas. Senn 2 ligated the pancreatic duct in dogs but was unable to produce a cyst, although it appeared that ectasia of the duct followed the ligation. He concluded that factors other than mere obstruction

Balantidia from Pigs and Guinea-Pigs: Their Viability, Cyst Production and Cultivation

It has been shown that trophozoites of balantidia from the pig are normal in appearance and reactions when the medium is cooled to room temperature. They may live at room temperature for ten days. Trophozoites that infect the pig may pass through the stomach of the guinea-pig and reach the cecum, where they are normal after eighteen hours. Trophozoites are frequently passed in feces by the pig but cyst production is irregular and determined by unknown factors as in monkeys, guinea-pigs and man. The fluid of pig feces from the cecum is slightly hypertonic to blood serum. The method of Barret and Yarbrough for the cultivation of Balantidium coli has been found practicable for Balantidium from the pig and guinea-pig. The addition of rice starch improves the medium and Ringer's solution without dextrose was found more suitable than 0.5 per cent. NaCl solution. Loeffler's beef blood serum may be substituted for human serum or horse serum. H(2)S appears non-toxic to Balantidium from the pig when passed into culture tubes.

Injections of spermatozoa and testicular substance into male rats.

In studying possible modifying effects on spermatogenesis, young adult male rats were injected subcutaneously and intraperitoneally with (1) freshly macerated testis suspensions and (2) with a suspension of rat spermatozoa. Subsequent matings were made with all injected males and the testes were later studied histologically. Agglutination tests were not made. It was found that one to five relatively heavy injections of these materials produced no specific effect on testicular activity within the limits of the experiment (three days to four months after the last injection). Smears from testes of previously injected males showed sperm motility, and litters obtained from matings proved the spermatozoa physiologically normal. Formed materials injected into the abdomen at times resulted in the production of cysts or abscesses sometimes located in the scrotum. When these latter were sufficiently large to cause displacement of the testis into the abdomen, the testis was found to be degenerate. Such degeneration, however, was not due to serological influences of the injected materials, but solely to the mechanical displacement of the organ; removed from the scrotal regulatory influences degeneration of the testis follows rapidly. In the abdomen degeneration is brought about through the exposure to higher than normal temperature for the testis and this degeneration should be carefully distinguished from supposed serological influences.