Effect of nitroglycerin on pharmacological properties of strophantinin vitro andin vivo

Tests of nitroglycerin for its impact on pharmacological properties of strohanthinin vivo using two rat models of heart failure andin vitro on isolated frog atria showed that nitroglycerin does not alter the toxicity or the negative chronotropic action of strophanthin while somewhat weakening its cardiotonic effect. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, No 4, pp. 387–390, April, 1995     

A novel,remote-controlled suspension device for brain tissue PO2 measurements with multiwire surface electrodes

A new device was developed for rapid assessment of PO₂ values in viable tissue, such as the brain, using a multiwire surface electrode. The instrument utilizes a phonograph-like construction with weightless suspension of the electrode which thus minimizes surface pressure and allows for compensation of brain movements. The new and original component of the present device is the motor-driven, servo-controlled rotation of the PO₂ electrode around its vertical axis. This enables PO₂ measurements from precisely defined locations. From values measured on rabbit brain surface a PO₂ histogram was constructed. The mean PO₂ and distribution histogram were similar to those obtained with a needle electrode. The novel device, therefore, enables accurate and fast tissue PO₂ measurements with minimal risk of brain damage.     

Bactericidal properties of a defocused Nd-YAG-laser beam

Nd-YAG laser radiation of 1.06 or 1.32 μ wavelength killed a proportion ofStaphylococcus aureus andEscherichia coli cells at power densities of 40 to 80 W/cm² and effected a 100% kill of these cells at a power density of 1000 W/cm². In blood agar, the radiation of 1.06 μ produced bactericidal effects to a depth twice that of the radiation of 1.32 μ. Laser radiation of these wavelengths did not cause elimination of R plasmids and had no effect on the antibiotic resistance of bacteria. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, No. 6, pp. 654–656, June, 1996     

In vitro velocity measurements in the near vicinity of the Bjork-Shiley aortic prosthesis using a laser-Doppler anemometer

In this study,in vitro velocity measurements in the near vicinity of a Björk-Shiley aortic valve, one of the more commonly used aortic valve prostheses, were made using a laser-Doppler anemometer. The velocity measurements identified a zone of stagnation, about 20 mm wide, immediately downstream from the fully open disc. The measurements also showed that the flow through the valve was divided into two unequal regions, namely, the major and minor outflow regions. Because of the low flow in the minor outflow region, the shear stresses along the perimeter of the valve in that region were considerably lower than the shear stresses along the sewing ring of the major outflow region. Pathologic studies of nine recovered Björk-Shiley aortic valves indicated varying amounts of thrombus formation on the outflow face of the disc and excess growth of endothelial tissue along the perimeter of the minor outflow region. If the large stagnation zone and the relatively low shear in the minor outflow region which were observed in thein vitro measurements also existin vivo, they could lead to the clinically observed thrombus formation and tissue overgrowth, respectively.     

Electric and dielectric properties of wet human cancellous bone as a function of frequency

In this study the electrical and dielectric properties of wet human cancellous bone from distal tibiae were examined as a function of frequency and direction. The resistance and capacitance of the cancellous bone specimens were measured at near 100% relative humidity. The measurements were made in all three orthogonal directions at discrete frequencies ranging from 120 Hz to 10 MHz using an LCR meter. At a frequency of 100 kHz, the mean resistivity and specific capacitance for the thirty cancellous bone specimens were 500 ohm-cm and 8.64 pF/cm in the longitudinal direction, 613 ohm-cm and 15.25 pF/cm in the anterior-posterior direction, and 609 ohm-cm and 14.64 pF/cm in the lateral-medial direction. All electrical and dielectric properties except the resistivity and the impedance were highly frequency dependent for the frequency range tested. All electrical and dielectric properties were transversely isotropic as the values for the longitudinal direction were different from values obtained for the two transverse directions and properties in the two transverse directions were approximately similar. Presented in part at the Fifth Southern Biomedical Engineering Conference held in Shreveport, Louisiana, October 20 and 21, 1988, and at the 13th Annual Meeting of the Society for Biomaterials held in New York, June 3–7, 1987. This work was supported by a grant No. ECS-8312680 from the National Science Foundation.     

In vitro detection of metastases of small-cell pulmonary carcinoma to the bone marrow using monoclonal antibodies

A panel of five monoclonal antibodies to surface antigens of small-cell pulmonary carcinoma was used for immunodiagnosis of metastases to the bone marrowin vitro in patients with small-cell carcinoma of the lungs. Standard cytomorphological diagnosis revealed metastases to the bone marrow in 6 out of 58 patients (10.3%). Using monoclonal antibodies, positive cells were detected in 12 (20.6%) patients, the tumor nature of the positive cells being undoubted in 7 preparations (12.6%). Five out of 6 cytologically positive cases were confirmed. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, No. 4, pp. 456–458, April, 1996 Presented by N. N. Trapeznikov, Member of the Russian Academy of Medical Sciences     

Development and in vitro validation of a device for measuring non-shunt cardiac output by nitrous oxide throughflow

A system has been developed for measuring non-shunt cardiac output by the throughflow technique, using nitrous oxide in patients undergoing general anaesthesia. The throughflow measurement technique is a non-invasive method based on inert gas throughflow theory. In vitro validation of the measurement system was performed using a lung gas exchange simulator. The accuracy and precision of the throughflow measurement system was assessed by comparing measured and target values for five simulated values of non-shunt cardiac output, from 2.88 to 9.86 l min⁻¹. This showed an overall mean bias of −0.03l min⁻¹ (range −0.00 to −0.10 l min⁻¹), with a mean coefficient of variation of the difference of 1.39% (1.20–1.93%). These results indicate that the measurement system is suitable for monitoring the non-shunt cardiac output in patients undergoing general anaesthesia using nitrous oxide throughflow.     

Analysis of changes in the electroencephalogram power spectrum on a new model of brain ischemia in rats

The bioelectrical activity is studied in the left and right parietal cortex by recording the power spectrum of the electroencephalogram in brain ischemia caused by complete ligation of the left common carotid artery and 50% reduction of the blood flow in the right common carotid artery in experiments carried out on nonnarcotized Wistar rats. Ischemia results in marked and stable disorders in the bioelectrical activity manifested in a decrease of the total EEG power, depression of the dominating frequency in the Θ-range, increase of the δ-range power, and interhemispheric asymmetry of some spectrogram parameters. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny Vol. 118, N ^o 12, pp. 565–567, December, 1994 Presented by E. D. Gol'dberg, Member of the Russian Academy of Medical Sciences     

Study of kinin-like properties of a new peptide isolated from bovine brain

Laboratory of Pharmacology, Institute of Organic Synthesis, Latvian Academy of Sciences. Laboratory of Neuropeptide Reception and Laboratory of New Biologically Active Peptides, M. M. Shemyakin Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow. (Presented by Academician K. V. Sudakov, Academy of Medical Sciences. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 4, pp. 386–387, April, 1992.     

Investigation of the constitutive proteins of brain structures by electrophoresis in a continuous polyacrylamide gel gradient in capillary tubes

A comparative investigation was made of the protein composition of structures of the rat brain (premotor cortex, area CA3 of the hippocampus, caudate nucleus, frontal lobe of the cerebellum) by electrophoresis in a continuous gradient of polyacrylamide gel (PAG) pores in capillary tubes. This method was shown to have much greater resolving power than electrophoresis in a uniform gel concentration. The method did not reveal any differences in the protein composition of the brain structures studied.Laboratory of Physiological Mechanisms of Memory Control, Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR N. P. Bekhtereva.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 11, pp. 621–623, November, 1978.     

In vitro cultivation of the microsporidian:Enterocytozoon salmonis using a newly developed medium for salmonid lymphocytes

Summary Techniques have been established for the continuous culture of a newly recognized salmonid microsporidian parasiteEnterocytozoon salmonis in salmonid mononuclear leukocytes. Utilization of human recombinant interleukin-2 (HrIL-2) and polyclonal mitogens in the culture medium supported viability of salmonid mononuclear leukocytes which allowed proliferation of the intracellular microsporidian parasite. The microsporidian maintained in primary culture for 45 days was infective both in cultures of mononuclear leukocytes and in juvenile salmonids. Additional passages of the agents from primary cultures to new cultures of uninfected mononuclear leukocytes have allowed continuous in vitro propagation ofE. salmonis. The parasites from these cultures retained developmental stages from early meronts to mature spores that were identical to those observed in naturally infected fish. Also, after cryopreservation in liquid nitrogen the parasites maintained their infectivity for juvenile chinook salmon and cell cultures of mononuclear leukocytes. The development of methods for the in vitro culture ofE. salmonis has made possible investigation of the effect of this microsporidian on immune functions of its key target cell, the mononuclear leukocyte.     

Development of a novel three-dimensional in vitro model of oral Candida infection

Oropharyngeal candidiasis is emerging as a serious health problem in the elderly as well as other chronically immunosuppressed patient populations. Several approaches have been used to study the interactions between Candida and the oral mucosa in vitro. Recently, three-dimensional organotypic systems of the oral mucosa have been developed, which provide an organizational complexity that is between the culture of single cell types and organ cultures in vivo. In this report we describe the development of a novel three-dimensional system of the human oral mucosa based on an immortalized oral keratinocyte cell line. Unlike the commercially available cell line systems, this system also contains a connective tissue cell component, which ensures the quality and resemblance of the tissue model to the human oral masticatory mucosa and submucosa. Using a panel of Candida albicans strains with variable virulence in vivo, we showed that the extent of tissue damage, fungal invasion and host inflammatory response in this system was proportional to the well-documented in vivo virulence potential of these strains. Therefore, this investigation has added another useful tool in the study of host pathogen interactions in oral candidiasis.     

In vitro validation of a right ventricular thermodilution ejection fraction system

Right ventricular ejection fraction (RVEF) is used clinically as an index of right ventricular (RV) pump function. Clinical measurements of RVEF are complicated by the need for complex imaging equipment to compute RV volumes. Recently, the use of thermodilution (TD) methods have been suggested as a simplified means to measure RVEF (RVEF_TD) in patients using rapid response thermistors. Validation, however, by comparison of RVEF_TD and other methodsin vivo, is difficult. Accordingly, thermodilution derived EF measurements (EF_TD) were compared to known values using anin vitro system, with known ejection fractions (EF) set from 17–78% and stroke rates varying independently from 50–100 strokes/min. EF_TD was computed by fitting the downslope of the TD curve to a monoexponential function and computing the time constant of thermal decay. A significant correlation existed between EF_TD and actual EF over the entire study (r=0.96, p<0.001). Bias analysis showed that the points were within a 95% confidence interval of ±12%. Multivariate analysis showed that stroke rate did not significantly affect TD measurements (r=0.03, p>0.7). This study demonstrates that TD accurately predicts EF using anin vitro system and appears to be independent of stroke rate. Thus, TD methods may provide an accurate, simple and reliable means to serially measure RVEF in the clinical setting. This work was supported in part by a Grant-in-Aid from the American Heart Association, and the Bioengineering Alliance of South Carolina.     

Disruption of the<Emphasis Type="Italic"> Aspergillus fumigatus argB</Emphasis> gene using a novel in vitro transposon-based mutagenesis approach

We disrupted the Aspergillus fumigatus argB gene, encoding ornithine transcarbamylase, using a novel in vitro transposon-based mutagenesis approach. This approach utilizes a modified transposon containing the Neurospora crassa pyr4 gene, which is randomly inserted in vitro into a target sequence of interest. Clones in which the gene of interest has been disrupted are identified by PCR and used to transform a pyrG-deficient strain of A. fumigatus. Using this approach, we obtained arginine auxotrophs of A. fumigatus. Full characterization of the argB insertion was performed by Southern blot analysis. These strains can be supplemented by addition of arginine into the culture medium and can be fully rescued to arginine prototrophy by transformation with the intact A. fumigatus argB gene.Communicated by U. Kück     

In vitro bioassay of endotoxin using fluorescein as a pH indicator in a macrophage cell culture system

Based on the biological activity of endotoxin, we propose a possible new method for detecting endotoxin using a pH-indication system of macrophage culture media. After RAW 264.7 macrophage cells were treated with lipopolysaccharide (LPS), the addition of fluorescein to the LPS-treated media reproductively reduced its absorption and emission spectra (it was a dose-dependent reduction). The advantages of this LPS-detection method were compared with the Limulus Amebocyte Lysate (LAL) test by using purified bacterial LPS (Salmonella minnessota, Escherichia coli, and Pseudomonas aeruginosa). Additionally, the absorption and fluorescence intensity of fluorescein, following treatment of RAW 264.7 cells with a high concentration of Staphylococcus aureus (Gram-positive, lysed bacteria), could not generally be detected by the LAL test, but they were found to be reduced, in a dose-response relationship, with this new system. The macrophage culture system-method might be a good supplement to the LAL assay for detection of LPS, Gram-negative and Gram-positive bacteria.     

Role of S fimbriae in Escherichia coli K1 binding to brain microvascular endothelial cells in vitro and penetration into the central nervous system in vivo

Bacterial binding to host cell surface is considered an important initial step in the pathogenesis of many infectious diseases including meningitis. Previous studies using a laboratory Escherichia coli (E. coli) strain HB101 possessing a recombinant plasmid carrying the cloned S fimbriae gene cluster have shown that S fimbriae are the major contributor to binding to bovine brain microvascular endothelial cells (BMEC) for HB101. Our present study, however, revealed that S fimbriae did not play a major role for E. coli K1's binding to human BMEC in vitro and crossing of the blood-brain barrier in vivo. This was shown by our demonstration that E. coli K1 strain and its S fimbriae-operon deletion mutant exhibited similar rates of binding to human BMEC and similar rates of penetration into the central nervous system in the experimental hematogenous meningitis model. Studies are needed to identify major determinants of E. coli K1 contributing to BMEC binding and subsequent crossing of the blood-brain barrier in vivo.     

In vitro selection of Haemonchus contortus for benzimidazole resistance reveals a mutation at amino acid 198 of β-tubulin

Benzimidazoles were the first broad-spectrum anthelmintics and are still in use today against gastro-intestinal nematodes of ruminants such as Haemonchus contortus. Benzimidazoles block the polymerization of nematode microtubules. However, their efficacy is jeopardized by the spread of drug-resistant parasites that carry point mutations in β-tubulin. Here we use a novel in vitro selection—in vivo propagation protocol to breed drug-resistant H. contortus. After 8 generations of selection with thiabendazole an in vitro resistance factor of 1000 was reached that was also relevant in vivo in infected sheep. The same procedure carried out with ivermectin produced only a moderate resistance phenotype that was not apparent in sheep. Cloning and sequencing of the β-tubulin genes from the thiabendazole-resistant H. contortus mutants revealed all of the isotype 1 alleles, and part of the isotype 2 alleles, to carry the mutation glutamate¹⁹⁸ to alanine (E198A). An allele-specific PCR was developed, which may be helpful in monitoring the prevalence of alanine¹⁹⁸ encoding alleles in the β-tubulin isotype 1 gene pool of H. contortus in the field.