Co-localization of the cysteine protease caspase-3 with apoptotic myocytes after in vivo myocardial ischemia and reperfusion in the rat

The aim of our study was to characterize the temporal relationship of apoptosis to regional myocardial ischemia and reperfusion and we aimed to determine the effect of ischemia and reperfusion on the distribution of the pro-apoptotic cysteine protease caspase-3 (CPP 32, apopain, Yama) in an in vivo rat model. Male Sprague-Dawley rats (250-400 g) were anesthetized with sodium pentobarbital (65 mg/kg, i.p.), the left external carotid artery was isolated to monitor arterial pressure and a left thoracotomy was performed. Regional myocardial ischemia was induced by occluding the left main coronary artery for 45 min. The heart was reperfused for 0, 60, 120 or 180 min. TUNEL staining of formalin-fixed, paraffin-embedded left ventricle, and DNA fragmentation analysis, showed that apoptosis occurred during 45 min of ischemia alone, but further developed during the 3-h reperfusion period. Immunohistochemical analysis of ischemic/reperfused left ventricle showed caspase-3 levels were substantially elevated and localized in the ischemic/reperfused region, and that caspase-3 co-localized to TUNEL positive myocytes. Therefore, regional myocardial ischemia serves as a stimulus for myocyte apoptosis, and this form of cell death progresses time-dependently after the onset of reperfusion. Our studies implicate caspase-3 to be involved in apoptotic cell death in ischemic/reperfused rat heart.     

Characteristics of AlGaAs/GaAs quantum-well delta-doped channel FET(QUADFET)

The transport properties of a two-dimensional electron gas in Al _0.3Ga_0.7As/GaAs quantum-well delta-doped heterostructures are studied. Electron energy subbands in the quantum well were calculated by a self-consistent method. The FETs having a gate length of 1.3 μm showed a transconductance as high as 340 mS/mm. The FETs also showed a broad plateau of transconductance around its peak, which is not typical in MODFETs     

Response phase of the flicker electroretinogram (ERG) is influenced by cone excitation strength

To measure cone signal strengths in the flicker electroretinogram (ERG) of dichromats and trichromats, we developed a set of flickering stimuli (30 Hz), which excite the middle-wavelength-sensitive (M-) and long-wavelength-sensitive (L-) cones independently. ERG responses to eight different ratios of L- to M-cone contrasts were recorded from each subject. The short-wavelength-sensitive (S-) cone contrast was 0% in all measurements. The recordings were Fourier analyzed to determine the amplitude of the fundamental component. ERG threshold values for each subject resulted in ellipses when plotted in an L-/M-cone contrast space. As expected, the orientations of the threshold ellipses of the protanopes (N = 2) were parallel to the L-cone axis, whereas those of the deuteranopes (N = 2) were parallel to the M-cone axis. For the trichromats (N = 5), there was considerable interindividual variation in ellipse orientation.     

In vitro growth of mastitis pathogens in mammary secretions of the dry and peripartum periods

In vitro growth of Escherichia coli, Streptococcus uberis, and Staphylococcus aureus was measured in skimmed, cell-free secretions of bovine mammary glands collected on d 0, 7, 14, and 28 of the dry period; 12, 8, and 4 d before expected calving; and on d 0 and 14 postpartum. There were marked and nearly inverse changes in growth of Escherichia coli and Streptococcus uberis over the experimental period. Escherichia coli grew well in secretions of d 0 of the dry period and d 0 and 14 postcalving but poorly or not at all in secretions of the mid-dry period. In contrast, Streptococcus uberis grew well in secretions of the involuted gland and poorly in samples from day of dry off and day of calving. Growth of Staphylococcus aureus changed relatively little over the dry period, but there was reduction in growth at d 7 of the dry period. Changing ability of the secretion to support bacterial growth may influence changing susceptibility to infection, but for Streptococcus uberis, poor correspondence between changes in growth supported by the secretion and changes in the incidence of naturally occurring infection over the dry period indicates that other factors may be more important.     

Effects of natural intramammary Corynebacterium bovis infection on milk yield and composition

The objective was to assess effect of Corynebacterium bovis infection of the bovine mammary gland on milk yield and composition. Yield and composition of milk from 53 Corynebacterium bovis-infected quarters of 44 cows at four consecutive milkings were compared with those of the contralateral uninfected quarters. Differences between infected and uninfected quarters in milk, fat, and protein yield and in fat and protein content were small and statistically nonsignificant. Numbers of somatic cells were moderately but significantly higher (119,000 vs. 79,000 cells/ml) in infected than in uninfected quarters.