THE PURIFICATION AND CONCENTRATION OF DIPHTHERIA TOXOID

By precipitation with acetone at 4°C. a refined diphtheria toxoid was obtained as a dry powder, readily soluble in aqueous solutions. The powder itself appears to be stable. When dissolved in half the original volume of physiological salt solution, the toxoid remained stable, in the cold room, for a period of 7 months. Only toxoids should be used which have been completely detoxified by the treatment with formalin. The formalin is immediately and completely removed by precipitation with acetone. Filtration through a Mandler filter or the addition of a preservative did not appear to have any deleterious effect. Incubating at 39°C. and freezing for 20 hours did not impair its activities. The flocculating value of the purified toxoid containing phenol was almost completely destroyed by freezing, while when merthiolate was the preservative, it was unchanged. Approximately 62 per cent of the nitrogen was eliminated in the process with approximately 15 per cent loss in flocculating value. The flocculating values were nearly double those of the original material and thus corresponded with the concentration, which was onehalf the volume. By this method, the antigenic activity of a toxoid below standard may be increased to a satisfactory standard. The antigenic activity of the refined product in the immunization of guinea pigs may in general parallel its flocculating values but the relation between the results of these tests may not be proportional nor constant. As an immunizing agent in the guinea pig, the refined toxoid possesses an antigenic activity that is equal to, or greater than, that of the unconcentrated toxoid.     

Early spontaneous metastasis in the human epidermoid carcinoma HEp3/chick embryo model: contribution of incidental colonization

In the experimental model system where human tumor cells (HEp3) are implanted on the chorioallantoic membrane (CAM) of the chick embryo, metastasis of HEp3 cells to the embryonic lung occurs within a few days. Such rapidity in tumor dissemination makes this an attractive and potentially useful model for studying the metastatic process. The model, however, involves microvascular trauma at the site of implantation and thus tumor cells may accidentally enter the circulation during implantation or shortly thereafter. If these cells are the cause of the lung metastasis subsequently measured, the model would be in effect a colonization system and not a true, spontaneous metastasis system. The possible contribution of accidental lung colonization to secondary tumor growth was therefore critically examined in this model. In standard metastasis assays, HEp3 was inoculated onto the CAMs of 10-day embryos, which were then incubated for various periods of time. The embryos' lungs were passaged to a second group of CAMs, incubated for 7 days to allow expansion of any HEp3 cells present, and then assayed for HEp3 cells by both microscopy and measurement of human plasminogen activator (PA) activity. Metastasis was evidenced by PA values above background (30 mU/mg protein). Morphological analysis of HEp3 cells in the embryonic lung correlated closely with PA values. To focus on the early stages of tumor dissemination when colonization might occur, the primary tumor was surgically excised from 38 embryos at various intervals after tumor inoculation, and after the operation embryos were allowed to develop to day 17. This procedure increased estimated assay sensitivity down to the level of 1 to 10 cells per lung in embryos operated on within 2 days of inoculation. Median PA values in the transplanted lungs were 13, 3, 37, 1,290 and 3,765 mU/mg protein in the groups operated on at 4 hr, 1, 2, 3 and 4 days after inoculation, respectively. Thus very few or no HEp3 cells arrest and grow in the lungs during the first 24 to 48 hr, but extensive metastasis occurs by 72-96 hr. Accidental colonization therefore plays no major part in the rapid pulmonary spread of HEp3 in this model.     

Identification of glaucoma-related visual field abnormality with the screening protocol of frequency doubling technology

Purpose: To evaluate the predictive power of frequency doubling technology to distinguish glaucoma suspects from persons with glaucoma visual field loss.Methods: A consecutive series of 76 subjects referred to a glaucoma service underwent perimetry in one eye with frequency doubling technology in a screening mode and Humphrey 24-2 threshold testing in random order, and had optic disk and clinical nerve fiber layer grading.Results: All subjects performed perimetry with both instruments satisfactorily, with an average test time of 1.8 ± 0.7 minutes per eye for the frequency doubling technology (instrument time). Of 33 eyes classified as abnormal by glaucoma hemifield test, 91% (30/33) were abnormal on frequency doubling technology (two or more abnormal locations of 17), whereas 94% (31/33) of glaucoma suspects with normal Humphrey fields had normal results with frequency doubling technology. Frequency doubling technology results were highly correlated with Humphrey mean deviation by linear regression (r² = .74, P = .047) and with corrected pattern standard deviation probability value. A frequency doubling technology error score for each quadrant of the field was highly correlated with the number of severely abnormal points per quadrant in Humphrey threshold tests (r² = .63, P = .034). There was close agreement between clinical examination of the optic disk and nerve fiber layer and frequency doubling technology results. Three-level quantification of abnormality in frequency doubling technology results did not add to diagnostic accuracy.Conclusion: Frequency doubling technology testing shows promise as a screening method in glaucoma.     

Percutaneous transluminal coronary angioplasty in unstable angina: comparison with stable angina.

Percutaneous transluminal coronary angioplasty was performed in 25 patients with unstable angina and in a similar group of 25 patients with stable angina. The frequency of single, double, and triple vessel disease was identical in each group. Technical success was achieved in 22 (81%) out of 27 attempts in those with unstable angina and in 14 (52%) out of 27 attempts in those with stable angina. Vessel occlusion occurred in nine patients, necessitating emergency bypass surgery in four. There was evidence of myocardial infarction in three patients in each group and one patient in the unstable group subsequently died. Twenty eight of 32 successfully treated patients were followed up by means of repeat coronary arteriography, exercise electrocardiography, and clinical assessment after a mean (SD) interval of 14 (7) months. There was angiographic evidence of restenosis in 32% (seven of 22) of lesions in the unstable group and 44% (four of nine) of lesions in the stable group. There were no late infarctions or deaths during the follow up period. These results support the growing evidence that angioplasty can be carried out safely and effectively in patients with unstable angina.     

Bursting pressure of experimental aneurysms

The laser-sealed arteriotomy (LSA) technique was used to create experimental aneurysms in the rat carotid artery. Animals were reexplored 2, 4, and 8 weeks following LSA, at which time the aneurysms were measured and subjected to a bursting strength pressure. In addition, a group of hypertensive rats with LSA was also tested 2 weeks after surgery. The LSA procedure produced aneurysms of a stable size and bursting pressure over the time studied. The bursting pressure technique may be applicable for assessing aneurysm therapy in an experimental setting.     

Acute renal failure due to obstruction in Burkitt lymphoma

 Acute renal failure in Burkitt lymphoma is commonly the result of tumor lysis syndrome. We present a 15-year-old boy who developed hypertension, seizures, and acute renal failure due to extrinsic compression of the bladder and ureters by a large retrovesical Burkitt lymphoma. The causes of acute renal failure in Burkitt lymphoma and the incidence of acute urinary obstruction in this disease are reviewed. Received: 18 May 1998 / Revised: 30 June 1998 / Accepted: 1 July 1998