Attempts to restore scrapie prion infectivity after exposure to protein denaturants

A wealth of experimental evidence argues that infectious prions are composed largely, if not entirely, of the scrapie isoform of the prion protein. We attempted to restore scrapie infectivity after exposure to protein denaturants including urea, chaotropic salts, and SDS. None of the procedures restored infectivity. Dialysis to remove slowly chaotropic ions and urea failed to restore scrapie infectivity. Attempts to create monomers of the scrapie isoform of the prion protein under nondenaturing conditions using a wide variety of detergents have been unsuccessful, to date, except for one report claiming that scrapie infectivity could be recovered from 12% polyacrylamide gels after SDS/PAGE [Brown, P., Liberski, P. P., Wolff, A. & Gajdusek, D. C. (1990) Proc. Natl. Acad. Sci. USA 87, 7240-7244]. We found that < 0.001% of the infectious prion titer could be recovered from the region of a polyacrylamide gel where the denatured proteinase K-resistant core of the scrapie isoform of the prion protein and other 30-kDa proteins migrate. We conclude that under the denaturing conditions used for SDS/PAGE, the scrapie isoform of the prion protein is denatured and little or no renaturation occurs upon injection of fractions eluted from gels into animals for bioassays.

Scrapie prion rod formation in vitro requires both detergent extraction and limited proteolysis

Scrapie prion infectivity can be enriched from hamster brain homogenates by using limited proteolysis and detergent extraction. Purified fractions contain both scrapie infectivity and the protein PrP 27-30, which is aggregated in the form of prion rods. During purification, PrP 27-30 is produced from a larger membrane protein, PrPSc, by limited proteolysis with proteinase K. Brain homogenates from scrapie-infected hamsters do not contain prion rods prior to exposure to detergents and proteases. To determine whether both detergent extraction and limited proteolysis are required for the formation of prion rods, microsomal membranes were prepared from infected brains in the presence of protease inhibitors. The isolated membranes were then detergent extracted as well as protease digested to evaluate the effects of these treatments on the formation of prion rods. Neither detergent (2% Sarkosyl) extraction nor limited proteinase K digestion of scrapie microsomes produced recognizable prion amyloid rods. Only after combining detergent extraction with limited proteolysis were numerous prion rods observed. Rod formation was influenced by the protease concentration, the specificity of the protease, and the duration of digestion. Rod formation also depended upon the detergent; some combinations of protease and detergent did not produce prion amyloid rods. Similar results were obtained with purified PrPSc fractions prepared by repeated detergent extractions in the presence of protease inhibitors. These fractions contained amorphous structures but not rods; however, prion rods were produced upon conversion of PrPSc to PrP 27-30 by limited proteolysis. We conclude that the formation of prion amyloid rods in vitro requires both detergent extraction and limited proteolysis. In vivo, amyloid filaments found in the brains of animals with scrapie resemble prion rods in their width and their labeling with prion protein (PrP) antisera; however, filaments are typically longer than rods. Whether limited proteolysis and some process equivalent to detergent extraction are required for amyloid filament formation in vivo remains to be established.

Investigations on the presence of antibodies to papova viruses in patients with different forms of cancer and in other categories of patients or apparently healthy subjects. Note I. Neutralizing antibodies to SV-40 in the cerebrospinal fluid of patients with brain tumors and chronic neurological diseases

Neutralizing antibodies to SV-40 were detected in cerebrospinal fluid samples from 16 out of 43 patients with brain tumors and in 6 out of 20 patients with different nonmalignant chronic neurological diseases. The patients' age excluded the correlation with a vaccine-associated or occupational contact with SV-40. The results ascertain the occurrence of SV-40 or of an antigenically related virus in the population of Romania.

Investigations on the presence of antibodies to papova viruses in patients with different forms of cancer and in other categories of patients or apparently healthy subjects. Note II. Hemagglutination-inhibiting serum antibodies to BK virus

Hemagglutination-inhibiting serum antibodies to BK virus (BKV were detected in patients with different forms of cancer and in blood donors (positivity percentages: 67.04 and 57.78, respectively). No such antibodies were found in a group of children 1 to 14 years of age. The data point to the presence of a latent human infection with BKV in the population of Romania.

Investigations on the presence of antibodies to papova viruses in patients with different forms of cancer and in other categories of patients or apparently healthy subjects. Note III. Hemagglutination-inhibiting serum antibodies to polyoma virus

Hemagglutination-inhibiting antibodies to polyoma virus could be detected in sera from apparently healthy subjects, patients with nonmalignant respiratory diseases and patients with different forms of cancer. The positivity percentages (12.97, 12.92 and 16.36, respectively) and the titers recorded were lower than in the case of BK virus. The results obtained suggest a slight antigenic relationship between polyoma and BK virus.

The diagnostic value of interpleural lymph node biopsy

The authors examined biopsies of the interpleural lymph nodes harvested by mediastinoscopy and hilloscopy in 162 patients (133 males and 29 females). The diagnostic efficiency is very high in sarcoidosis, silicosis and in Hodgkin's disease. In sarcoidosis biopsy is able to indicate the evolutive stage of the disease. In malignant lymphogranulomatosis all the observations belonged to type II of nodular sclerosis. In bronchial carcinoma interpleural lymph node biopsy may be practised with diagnostic purposes or in order to check up operability.

Hemorrhagic fever with renal syndrome: report of 11 observations

Based on the observation of 11 patients (10 males and 1 female), the occurrence of hemorrhagic fever with renal syndrome in two new geographic areas of Romania is reported. Two patients died within several hours after admission. The other nine recovered gradually. In four patients hemodialysis was necessary. A complete recovery of renal functions one year after onset could be proved in four patients. The clinical, laboratory, morphopathological (necroptic and bioptic), epidemiologic and evolutive characteristics of the disease, especially the main features supporting the diagnosis of hemorrhagic fever with renal syndrome, are discussed.

Immunoblastic lymphadenopathy with centrofollicular PAS-positive inclusions

The authors describe the clinical and histopathologic picture of immunoblastic lymphadenomegaly in a 66-year-old patient with allergic antecedents. The condition of the patient ameliorated following cortisone and antibiotic therapy, but adenomegalia relapsed after several months. PAS-positive granular inclusions were found in the macrophage cells in the germinative centres of the follicles, showing the aspect of a blockade with nuclear significance.

Anatomo-pathologic observations on epidemic nephropathy

Two cases of necropsy and 5 cases of renal biopuncture were studied on the occassion of an epidemic of "hemorrhagic fever with renal syndrome" identified in mountainous areas of Transylvania. The prevalent pathogenic process was capillary toxicosis which injured the renal tubules and vessels. The severity of the disease was determined by the phenomena of tubular failure, by the hemorrhagic syndrome and shock.