Assessment of bactericidal and growth-inhibiting activity of blood serum using flow cytometry and photometry

Method of measurement of biological fluids bactericidal activity against Staphylococcus aureus using laser flow cytometry has been developed and proposed for clinical use. Overall bactericidal activity of sera of healthy donors has been assessed by this method. Strong positive correlation between bactericidal activity measured by flow cytometry and ability of the sera of healthy donors to inhibit bacterial growth assessed by photometric method was determined. High degree of positive correlation between results of cytometry and classical microbiological method of measurement of mentioned parameters has been shown.     

Mechanism of the decrease in intracranial pressure as affected by furosemide

The correlation was established between the increase in diuresis and natriuresis and fall of CSF pressure after intravenous injection of 10 mg/kg furosemide into dogs. Osmolarity and ion concentration in the serum and CSF did not change in these experiments. In nephrectomized dogs, furosemide did not changes CSF pressure. Furosemide dehydrated brain with traumatic edema, reduced brain Fe content probably due to diminishing brain blood content. The mechanism of intracranial pressure fall after furosemide injection can be explained by acute excretion of a large volume of fluid by the kidneys, leading to a decrease in the blood content of the skull cavity.     

Suppression of the immune response to ovalbumin in vivo using anti-idiotypic antibodies

The effect of anti-idiotype antibodies (a-IdpI) on primary immune response to ovalbumin (OVA) was studied. A-IdpI against OVA antibodies were obtained with pI 6.2-6.7 from BALB/c mice. About 30-40% of IgG plaque cell formation (PCF) was inhibited if a-IdpI antiserum was added in situ, which served as a test for the evaluation of idiotype-positive (Id+) PCF. Up to 70% of common PCF and 70-80% of Id+ PCF were suppressed in mice that were injected with a-IdpI antibodies prior to immunization. This suppression was antigen- and allo-specific and depended upon the time of a-IdpI injection. If a-IdpI antibodies were disaggregated (DA) the Id+ suppression increased. A-IdpI antibodies also decreased IgE response to OVA, the suppression being most pronounced with the use of DA samples.     

Screening of natural immunosuppressors by their ability to modify steroid synthesis in hepatocytes]

In the programme for screening sterol synthesis inhibitors with the use of actinomycetes and fungi 702 strains were tested. The effect of alcohol extracts of the mycelium of fungi and actinomycetes at a dilution of 1/10(3) on sterol synthesis by the Hep G2 hepatome cells was determined by incorporation of 3H acetate into sterols and proteins. Lovastatin (200 pg/ml) was used as the control: the sterol synthesis was decreased by 49 +/- 4% without inhibiting the protein synthesis. A number of the cultures produced compounds inhibiting under the experimental conditions the synthesis of sterols by 70 to 80% with simultaneous inhibition of the protein synthesis at least by 60 to 70%. Three compounds from that group produced by streptomycetes were subjected to a more detailed investigation. The compounds were demonstrated to be active antifungal antibiotics (MIC 0.1-1 mcg/ml). In a dose of 0.1-1 mcg/ml they showed high immunosuppressive activity in models of lymphocyte transformation in mice, whereas cyclosporin was active in a dose of 1 mcg/ml. Therefore, the model for screening hypolipidemic compounds could be considered useful for screening promising natural immunosuppressors.     

Retroviral transfer of the p16INK4a cDNA inhibits C6 glioma formation in Wistar rats

BACKGROUND: The p16INK4A gene product halts cell proliferation by preventing phosphorylation of the Rb protein. The p16INK4a gene is often deleted in human glioblastoma multiforme, contributing to unchecked Rb phosphorylation and rapid cell division. We show here that transduction of the human p16INK4a cDNA using the pCL retroviral system is an efficient means of stopping the proliferation of the rat-derrived glioma cell line, C6, both in tissue culture and in an animal model. C6 cells were transduced with pCL retrovirus encoding the p16INK4a, p53, or Rb genes. These cells were analyzed by a colony formation assay. Expression of p16INK4a was confirmed by immunohistochemistry and Western blot analysis. The altered morphology of the p16-expressing cells was further characterized by the senescence-associated beta-galactosidase assay. C6 cells infected ex vivo were implanted by stereotaxic injection in order to assess tumor formation. RESULTS: The p16INK4a gene arrested C6 cells more efficiently than either p53 or Rb. Continued studies with the p16INK4a gene revealed that a large portion of infected cells expressed the p16INK4a protein and the morphology of these cells was altered. The enlarged, flat, and bi-polar shape indicated a senescence-like state, confirmed by the senescence-associated beta-galactosidase assay. The animal model revealed that cells infected with the pCLp16 virus did not form tumors. CONCLUSION: Our results show that retrovirus mediated transfer of p16INK4a halts glioma formation in a rat model. These results corroborate the idea that retrovirus-mediated transfer of the p16INK4a gene may be an effective means to arrest human glioma and glioblastoma.