Effects of cardioselective beta blockers on ventilation and gas exchange in patients with heart disease during ramp treadmill testing

The effects of cardioselective beta blockade on ventilation and gas exchange were investigated in 12 male subjects with coronary artery disease during ramp treadmill testing. Patients were able to maintain much of their functional capacity as measured by oxygen consumption in the beta-blocked condition, and also maintained minute ventilation by increasing respiratory rate despite a decrease in tidal volume.     

Drug interactions: keeping it straight

Drug interactions are common causes of treatment failure and adverse reactions. Patients who have a number of chronic disorders, patients who take many medications or patients who have impaired renal function are at increased risk for these problems. Special attention must be given to drugs that require blood level monitoring, because these agents have a narrow margin of safety. Drug interactions are especially likely to occur with enzyme inhibitors such as erythromycin, cimetidine, ciprofloxacin and metronidazole. Mechanisms of drug interactions include problems with absorption secondary to binding by antacids or other cations, interference with the distribution of drugs secondary to the displacement of highly protein-bound drugs, differences in metabolism secondary to variability of the cytochrome P450 enzyme system, and interaction-related problems with drug excretion by renal tubules. Antagonistic and synergistic reactions also need to be considered. Finally, the time course in which a given drug interaction is likely to occur must be taken into account when deciding whether the interaction is responsible for an adverse effect or treatment failure.     

Membrane capacitance changes associated with particle uptake during phagocytosis in macrophages

We report the use of capacitance measurements to monitor particle uptake after cellular exposure to phagocytic stimuli. In these studies, human monocyte-derived macrophages (HMDMs) and cells from the murine macrophage-like cell line J774.1 were exposed to immune complexes or sized latex particles (0.8 or 3.2 micron in diameter). An average decrease in cell capacitance of 8 pF was seen after exposure of the cells to immune complexes. Cells in which particle uptake was inhibited by cytochalasin B treatment before exposure to immune complexes showed an average increase of 0.5 pF. The decrease in membrane capacitance after exposure of cells to particulate stimuli was absent with the soluble stimulus, platelet-activating factor, further confirming that decreases in membrane capacitance were due to particle uptake. Exposure of cells to sized latex particles resulted in a graded, stepwise decrease in membrane capacitance. The average step size for 0.8-micron particles was 250 fF, and the average step change for the larger 3.2-micron particles was 480 fF, as calculated from Gaussian fits to the step size amplitude histograms. The predicted step size for the individual particles based upon the minimum amount of membrane required to enclose a particle and a specific capacitance of 10 fF/micron2 was 20 and 320 fF, respectively. The step size for the smaller particles deviates significantly from the predicted size distribution, indicating either a possible lower limit to the size of the phagocytic vacuole or multiple particles taken up within a single phagosome. Dynamic interaction between phagocytosis and exocytosis was observed in a number of cells as a biphasic response consisting of an initial rapid increase in capacitance, consistent with cellular exocytosis, followed by stepwise decreases in capacitance.     

Childhood traumatic brain injury: initial impact on the family

Traumatic brain injury (TBI) is a significant source of morbidity and mortality in children, resulting in a wide range of cognitive and behavioral sequelae. However, little is known about the effects of pediatric TBI and its aftermath on families. The current investigation examined the impact of TBI on families during the first month following injury. Children with orthopedic injuries requiring hospitalization served as a control group. The sample consisted of 44 families of children of severe TBI, 52 families of children with moderate TBI, and 69 families of children with orthopedic injuries not involving the central nervous system (CNS). Families of children with severe TBI experienced significantly more injury-related stress than the other two groups of families. Parents of children with TBI also reported higher levels of psychological symptoms than parents of children with orthopedic injuries. Findings from regression analyses suggested that families facing multiple stressors in addition to the injury and those who cope poorly may be at greatest risk for adverse consequences. Future interventions could provide anticipatory guidance and support to at-risk families.     

The failure of fibre composites and adhesively bonded fibre composites under high rates of test

The dynamic effects which are commonly encountered during high-rate DCB tests with fibre composite and adhesively bonded fibre composite arms have been studied in detail. This paper, Part II of the series, follows Part I, which described the experimental aspects of the high-rate testing. Part III will report the results from mode II and mixed-mode I/II tests on the fibre-composite materials.Nomenclature a crack length - a ₀ initial crack length - a crack speed - ä crack acceleration - c longitudinal wave speed - h thickness of single arm of test specimen - p crack length perturbation (i.e. the measured value of the crack length minus the value predic ted by steady-state theory) - p crack velocity perturbation - crack acceleration perturbation - t time - t ₀ time taken for crack to initiate during the mode I test - u ₀ load-line vertical displacement of single arm of test specimen (/2 in Part I) - u(x) vertical displacement of specimen at distance x from the load-line - u(x) vertical displacement rate of specimen at distance x from the load-line - x distance along the test specimen from the load-line - A constant relating the steady state crack length to root time - B width of specimen - C compliance of the specimen (u ₀/P) - E ₁₁ axial modulus of the fibre-composite beam - G mode I energy release rate - G _Ic mode I critical energy release rate or fracture toughness - G ₁ half the value of G _Ic during steady-state propagation (i.e. calculated for half the beam as shown in Fig. 1) - G ₂ half the value of G _Ic at crack initiation - P end load applied to specimen - U _ext external work done - U _s strain energy - U _k kinetic energy - V velocity of a single arm of test specimen (i.e. half the measured test velocity) - dynamic term, governed by the ratio of the energy to initiate versus that to propagate a crack - _I mode I crack shear deflection and root rotation correction term - crack length correction term, evaluated by the negative intercept on the a versus t ^1/2 plot - dynamic term controlling the form of the computed perturbations - Poisson's ratio for the fibre-composite beams density of the fibre-composite beams - time, normalized by the initiation time, t ₀ and thus equivalent to (t/t ₀) - values of at which crack arrest occurs. n = 1,2,3... - ratio of distance along beam to crack length (x/a)     

Note on Geheimschreiber Cam Wheels

ABSTRACT

This note shows that the cams in the Geheimschreiber could be installed in a reversed position and provides support for the contention that the same cam set was used in all models of the machine.