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Biomedical subjects

P C Licursi

Publications and source records attributed to P C Licursi.

8 recordsLinked to original sources
PubMed1976

Scrapie in vitro: agent replication and reduced cell yield.

Exposure of PAM cells, a spontaneously transformed mouse cell line, to brain homogenates from mice infected with scrapie caused a relative decrease in total cell yield, which persisted from passage 2 or 3 to passage 18 after treatment. The effect was elicited by each of the eight independent scrapie isolates tested. Lysates prepared from cultures 16 passages after treatment with scrapie caused the decrease when applied to fresh PAM cultures. Mice inoculated with passage 14 and 18 lysates developed a reduced percentage of polymorphonuclear neutrophils by 5 weeks and scrapie disease by 6 to 9 months after inoculation. Based on the total dilution from treatment of the PAM cultures with scrapie material to the preparation of the lysates, we conclude that the agent(s) responsible for the reduced PAM cell yield, the decreased percentage of polymorphonuclear neutrophils, and the induction of scrapie disease had replicated in the PAM cells. By filtration, the diameter of the agent causing the reduction in cell yield was estimated to be between 25 and 50 nm.

Animals↗
PubMed1975

Multiple sclerosis-induced reduction in the yield of a mouse cell line.

Cultures of a mouse cell line (PAM) were treated with 71 multiple sclerosis (MS) and 45 non-MS samples. Of the cultures treated with MS material, 80 percent (58) showed a reduction in cell yield (compared to untreated controls) of at least 20 percent by the third passage after inoculation. The MS samples were from 40 MS cases, and a total of 36 cases yielded at least one positive sample. The agent responsible for the decrease was not limited to nervous tissue, but was also found in serum, cerebrospinal fluid, spleen, kidney, and lymph node of MS patients. Positive samples were present at every stage of the disease. None of the non-MS samples yielded cell counts significantly different from untreated controls. The non-MS category included 12 samples from healthy individuals, 13 assorted non-central nervous system disease samples, and the following central nervous system disease samples: six subacute sclerosing panencephalitis, three Huntington's chorea, two Parkinsonism, six amyotrophic lateral sclerosis, one stroke, one encephalopathy, and one epilepsy. Brain homogenates from mice inoculated with MS tissues elicited the decrease, whereas brain homogenates from mice inoculated with non-MS samples did not.

Animals↗
PubMed1974

Reduced cell yields of mouse cell line cultures after exposure to homogenates of multiple sclerosis tissues.

The total cell yields in cultures of a mouse cell line termed "PAM" were reduced markedly after exposure to multiple sclerosis (MS) homogenates. The reductions were noted as early as the second subcultivation. The effect was produced by eight of eight MS brain homogenates and three of three MS spleen homogenates; the samples were from 10 MS cases. The reduction in total cell yields (compared to medium-treated cultures) was not observed after exposure to homogenates, six brain and two spleen, from eight non-MS cases. The effect was produced by the 50-nm filtrate of a pool of MS brain homogenates. Five of the MS-inoculated cultures were maintained for 18 subcultivations, and the reduction in total cell yields persisted throughout the series. The capacity to induce the reduction in cell yields was present in cell-free lysates from five of five MS cultures at passage 18, as was the capacity to cause a decrease in the polymorphonuclear neutrophils in the peripheral blood of mice. Calculation of the dilution effect (at least 10(18)-fold) that had occurred by the end of the passage series proved that the factor(s) causing the cell change in culture and the polymorphonuclear neutrophil change in mice had replicated in PAM cells.

Animals↗
PubMed1972

Decreased percentage of polymorphonuclear neutrophils in mouse peripheral blood after inoculation with material from multiple sclerosis patients.

Mice inoculated with brain homogenates from multiple sclerosis (MS) cases showed marked changes in their leukocyte differential counts, with a decrease in per cent polymorphonuclear neutrophils (PMN) and an increase in the per cent lymphocytes. These changes were based upon an absolute decrease in the number of circulating PMN. The decrease in PMN percentages was apparent at 16 hr after infection and persisted for at least 11 months. The factor responsible for the decrease in PMN was (a) recoverable from 12 hr to 8(1/2) months after inoculation, (b) present in human brain homogenate at a concentration of 3 x 10(12), and (c) between 25 and 50 nm in diameter. Inoculation of 100 units of factor into mice and subsequent titration showed that the factor had undergone a net increase in the mouse of at least 10(9)-fold. The factor causing the PMN decrease was found in all MS material thus far tested: three brains, one spleen, three sera, and two cerebrospinal fluid (CSF) from nine cases of MS. The factor was not found in normal human material that included two brains, one spleen, two sera, and two CSF.

Animals↗
PubMed1972

Scrapie-induced changes in the percentage of polymorphonuclear neutrophils in mouse peripheral blood.

A decrease in the percentage of polymorphonuclear neutrophils (PMN) in the peripheral blood of mice appeared 3 days after intracerebral (IC) inoculation with scrapie mouse brain homogenate. Mice inoculated IC with normal mouse brain had PMN percentages similar to those found for uninoculated mice. This difference between normal and scrapie-inoculated mice continued throughout the preclinical phase of the disease. In the clinical phase of the disease, the percentage of PMN was either higher or lower than that found in normals. The factor causing the decrease in PMN percentages was found in the filtrates from 220-, 100-, and 50-nm filters, but not in the filtrates from a 25-nm filter. Sodium periodate treatment of the scrapie brain samples eliminated their ability to cause the decrease in PMN percentages, whereas sodium iodate had no effect. In addition to two genetically different scrapie mouse brain isolates, homogenates of mouse spleen, sheep brain, and sheep spleen from scrapie-affected animals caused a decrease in percent PMN, whereas the corresponding normal tissue homogenates did not.

Animals↗