Isolation of amylopectin granules and identification of amylopectin phosphorylase in the oocysts of Eimeria tenella

Amylopectin granules were purified from Eimeria tenella oocysts following digestion with sodium dodecyl sulfate and pronase. The oval granules had a uniform size of 0.5 X 0.7 mum, and consisted of only glucose polymers. alpha-Amylase treatment yielded 235 nmoles of maltose from the granules from 10(6) unsporulated oocysts and 93 nmoles maltose from those from 10(6) sporulated oocysts. Amylopectin phosphorylase activity was detected in the cytoplasm of unsporulated oocysts of E. tenella. It had a specific activity of 13 U/mg protein in crude extracts, and a pH optimum of 6.0. The Km values determined were 9.1 mM for glucose-1-phosphate and 5.6 mM for glucose end groups in potato amylopectin. Enzyme activity declined at a linear rate during sporulation, sporulated oocysts containing less than 8% of the activity of unsporulated oocysts. No amylase-type activity was found in the parasite.

Rethinking the necessity of treating all fields at each radiotherapy session

Examples of multifield and wedged treatment plans are evaluated in terms of the fractionation protocol. Isoeffect distributions derived from time-dose fractionation values are examined, emphasizing alternate treatment schedules of the same plan. The necessity of treating all fields at each session is found to be a function of the detailed nature of the individual treatment plan.

Dihydrofolate reductase from Eimeria tenella: rationalization of chemotherapeutic efficacy of pyrimethamine

Dihydrofolate reductase activity of 0.2 nmole of dihydrofolate reduced/min/mg protein was detected in crude extracts of unsporulated oocysts of Eimeria tenella. The enzyme was purified by a combination of affinity and ion-exchange chromatography. Its molecular weight was estimated as 240,000 daltons. An anticoccidial drug pyrimethamine is a potent inhibitor of the activity of E. tenella dihydrofolate reductase (Ki = 3 nM), but it is less effective an inhibitor of dihydrofolate reductase from chicken liver. This difference may explain the in vivo therapeutic action of pyrimethamine against Coccidia.

Pancreatic chymotrypsin as the essential enzyme for excystation of Eimeria tenella

Sporocysts from the protozoan parasite, Eimeria tenella, were isolated, preincubated with sodium taurocholate, and treated with various preparations of pancreatic enzymes. Crude trypsin, crude lipase, and purified alpha-chymotrypsin all could break the shells of sporocysts and release sporozoites. Purified trypsin was much less active than crude trypsin and purified lipase showed no activity at all. Specific inhibitors of chymotrypsin, tosyl-L-phenylalanyl chloromethane, diphenylcarbamyl chloride, and chymostatin inhibited the release of sporozoites by all the enzyme samples, whereas tosyl-L-lysyl chloromethane, a specific inhibitor of trypsin, exerted no inhibitory effect. It is thus postulated that chymotrypsin, not trypsin, is an essential enzyme involved in excystation of E. tenella. Purified chymotrypsin is recommended to replace crude trypsin in the vitro excystation of E. tenella as a likely improved procedure.

An afterloading applicator for intracavitary vaginal irradiation

An afterloading apllicator for intracavitary vaginal irradiation that employs 137Cs sources in a T-shaped irradiator is described.

Hydroxyl Radical Concentrations Measured in Ambient Air

Diurnal variations in the hydroxyl radical concentration of ambient air were measured for the first time by the technique of laser-induced fluorescence.

Radiation therapy in the management of carcinoma of the external auditory canal, middle ear, or mastoid

Twenty-three patients with squamous-cell carcinoma of the external auditory canal, middle ear, or mastoid were treated with combined surgery and irradiation, giving a 5-year NED rate of 48% (11/23). Except in extremely early lesions without bone involvement, treatment by radiation therapy alone was rarely successful and is not recommended. The most serious complication was osteoradionecrosis of the temporal bone; this occurred in 5 patients, all of whom received more than 2,100 rets due to faulty radiotherapeutic technique.

Studies of the mitochondria from Eimeria tenella and inhibition of the electron transport by quinolone coccidiostats

Intact but fragile mitochondria were isolated from unsporulated oocysts of Eimeria tenella. The mitochondria respired in response to succinate, malate plus pyruvate, and L-ascorbate at rates of 1.00, 0.40, and 0.25 mu1 O2/min/mg protein, respectively. Spectrophotometric analyses of the cytochromes in mitochondria and whole oocysts revealed b-type and o-type cytochromes, at roughly similar levels, but no cytochrome c could be detected. The mitochondrial respiration was inhibited by cyanide, azide, carbon monoxide, antimycin A, and 2-heptyl-4-hydroxyquinoline-N-oxide, but was relatively resistant to rotenone and amytal. The quinolone coccidiostats buquinolate, amquinate, methyl benzoquate, and decoquinate were identified as very powerful inhibitiors of succinate and malate plus pyruvate supported respiration in E. tenella mitochondria. None of these four drugs exhibited any inhibitory effect on chicken liver mitochondria. Only 3 pmol of the quinolones per mg mitochondrial protein was needed to achieve 50% inhibition. The inhibition could not be reversed by coenzymes Q6 or Q10. Since the quinolones did not affect L-ascorbate-supported respiration or the activities of submitochondrial succinate dehydrogenase and NADH dehydrogenase, the site of action of the quinolone coccidiostats was tentatively identified as probably near cytochrome b in E. tenella mitochondria. Mitochondria isolated from an E. tenella amquinate-resistant mutant were much less susceptible to quinolone coccidiostats; 50% inhibition was attained by 300 pmol of the drugs/mg mitochondrial protein. The results suggest that the mechanisms of action of quinolone coccidiostats is by inhibiting the cytochrome-mediated electron transport in the mitochondria of coccidia. 2-Hydroxynaphthoquinone coccidiostats were identified as inhibitors of mitochondrial respiration of both E. tenella and chicken liver. They inhibited submitochondrial succinate dehydrogenase and NADH dehydrogenase of E. tenella, and remained equally active against the mitochondrial function of E. tenella amquinolate-resistant mutant.

Radiation therapy for head and neck cancers

A general review of the therapeutic experience of the management of carcinoma of the head and neck at the Massachusetts General Hospital and Massachusetts Eye and Ear Infirmary is presented. Early lesions are highly curable by radiation therapy alone; the advanced lesions are preferably treated by combined irradiation and surgery, with improved survival rates. Concepts of various approaches are discussed.

Preparation and purification of merozoites of Eimeria tenella

Second-generation merozoites of Eimeria tenella were obtained from both infected cecal tissue and infected chorioallantoic membranes of embryonated eggs. The merozoites were harvested from the tissue by incubation with hyaluronidase, yielding approximately 4 times 10(7) merozoites per cecum and 3 times 10(6) merozoites per chorioallantoic membrane. Subsequent purification of the merozoites by density centrifugation and glass bead filtration resulted in a 54% overall yield and a final preparation of approximately 95% purity. The viability of such preparations was established by inoculation of the merozoites to the ceca of chickens, resulting in oocyst production by 48 hr. This purification procedure allows for a rapid preparation of E. tenella during its second asexual stage in sufficient quantity and purity for biochemical study.

A simple afterloading applicator for intracavitary irradiation of carcinoma of the nasopharynx

A simple, disposable afterloading applicator for intracavitary irradiation of carcinoma of the nasopharynx has been found useful as a supplementary radiation boost to the primary site. Hopefully, local tumor control can be enhanced by employing this technique.

Reticulum cell sarcoma of the brain. A review of the literature and a study of 19 cases

Reticulum cell sarcoma of the brain is a rare neoplasm. However, patients who have been recipients of transplants have had a much higher than expected incidence of this tumor; reticulum cell sarcomas of the brain may be seen more often in the future. Most of the information available in the literature deals with the pathology and clinical course of the disease. Although several authors have commented on the radioresponsiveness of the tumor, little detail as to the exact treatment methods has been provided. Furthermore, it has been assumed that the prognosis of this tumor, after some form of surgery and postoperative radiotherapy, may be fairly good. This paper presents 19 patients who have had surgery followed by postoperative radiotherapy. Although a few patients have had good relief of symptoms for 3 to 4 years, only 1 patient is alive and free of disease over 5 years. This patient is the sixth reported long-term survival in the literature. Suggestions for the management of this disease are provided. If possible, limited surgery to remove circumscribed tumors should be done, but extensive resection should be avoided. Postoperative irradiation should include the whole brain to at least 4500 rads at 1000 rads per week, with a boost to residual tumor, if present, of 500 to 1000 rads in two to five treatments.

A study of carbohydrate metabolism in postnecrotic cirrhosis liver

Intravenous glucose tolerance, insulin tolerance, tolbutamide, and glucagon tests were carried out in 21 patients with postnecrotic cirrhosis. Based arbitrarily on the bromsulphthalein retention they were divided into group A, nine patients with less impaired liver function, and group B, 12 patients with greater impairment of liver function. Intravenous glucose and insulin tolerances were reduced in both groups. The hypoglycaemic effect of tolbutamide was similar in the controls and in both groups of cirrhotic patients but this was achieved at higher plasma insulin levels in group B indicating resistance of the liver to the effect of endogenous insulin. The blood glucose response to glucagon was markedly impaired in group B patients which is consistent with this hypothesis. In contrast to the insulin response to glucose and tolbutamide, the insulin response to glucagon was reduced in the cirrhotic patients. Fasting human growth hormone and free fatty acid levels were elevated in both groups but they were not considered to be important factors in the production of insulin resistance.