Biological evaluation of a mechanical ventilator that operates by controlling an automated manual resuscitator. A descriptive study in swine

The Covid-19 outbreak challenged health systems around the world to design and implement cost-effective devices produced locally to meet the increased demand of mechanical ventilators worldwide. This study evaluates the physiological responses of healthy swine maintained under volume- or pressure-controlled mechanical ventilation by a mechanical ventilator implemented to bring life-support by automating a resuscitation bag and closely controlling ventilatory parameters. Physiological parameters were monitored in eight sedated animals (t₀) prior to inducing deep anaesthesia, and during the next six hours of mechanical ventilation (t₁-₇). Hemodynamic conditions were monitored periodically using a portable gas analyser machine (i.e. BEecf, carbonate, SaO₂, lactate, pH, PaO₂, PaCO₂) and a capnometer (i.e. ETCO₂). Electrocardiogram, echocardiography and lung ultrasonography were performed to detect in vivo alterations in these vital organs and pathological findings from necropsy were reported. The mechanical ventilator properly controlled physiological levels of blood biochemistry such as oxygenation parameters (PaO₂, PaCO₂, SaO₂, ETCO₂), acid-base equilibrium (pH, carbonate, BEecf), and perfusion of tissues (lactate levels). In addition, histopathological analysis showed no evidence of acute tissue damage in lung, heart, liver, kidney, or brain. All animals were able to breathe spontaneously after undergoing mechanical ventilation. These preclinical data, supports the biological safety of the medical device to move forward to further evaluation in clinical studies.

Detection of antibodies to mycoplasmas in South American camelids

Indirect haemagglutination tests on sera from 757 South American camelids (alpacas, llamas and vicunas) carried out in the Andean region of Peru, revealed evidence of exposure mainly to Mycoplasma mycoides subspecies mycoides LC. The incidence of detectable antibodies to this mycoplasma in 554 alpacas was 5.0 per cent and in 141 llamas 15.6 per cent. Antibody to Mycoplasma capricolum and the F38 biotype was detected in 0.9 per cent and 0.2 per cent of alpacas, respectively. In a group of 62 vicunas only one reactor to both M m mycoides LC and M capricolum was observed. No reactors to M mycoides subspecies capri or M agalactiae were observed in the flocks examined. Antibodies to mycoplasma were also detected in nine out of 10 goat flocks tested. The incidence of antibodies to M m mycoides LC was 13.8 per cent, 3.8 per cent for M capricolum and 1.8 per cent for the F38 biotype. In a group of 110 sheep, six reactors (5.5 per cent) to M m mycoides LC and one (0.9 per cent) to F38 were observed. The implications of these results are discussed in relation to the involvement of mycoplasmas in existing disease in camelids in Peru.

The antitumor effects of anthracyclines. II. The stereospecificity of the carbomethoxy group at position 10 of the class II anthracycline molecule

The effects of marcellomycin, musettamycin, and their respective position 10 epimers mimimycin and collinemycin were compared in several systems both in vivo and in vitro. The results of these studies showed that the epimerization of the carbomethoxy-group at position 10 of the Class II anthracycline aglycone resulted in a 3-fold to 20-fold decrease in DNA-binding ability. The reduced DNA binding ability of these compounds is correlated with a 2-fold to 17-fold decrease in whole cellular nucleic acid synthesis inhibitory potency, a 2-fold to 4-fold decrease in vitro antitumor potency, and a 4-fold to 32-fold reduction in in vivo antitumor potency. These results further support the concept that a major portion of the antitumor activity of Class II anthracyclines is related to their avidity for DNA interactions and resultant disruption of normal template function. Previous studies from this laboratory have demonstrated that the 10-carbomethoxy group is essential for nucleolar RNA synthesis inhibition and Class II anthracycline antitumor activity. The current study further demonstrates that the stereochemical orientation of the carbomethoxy group at position 10 of the aglycone is also important in conferring Class II anthracycline antitumor activity.