Acquired air-filled lung cysts in childhood: pathogenesis of cysts of diverse etiologies; nuances of management

Background Air-filled pulmonary parenchymal cysts (pneumatoceles/PCs) – a pathological condition – involving the lung parenchyma may be congenital or acquired. In children, acquired cases are often caused by staphylococcal pneumonias, but other etiologies may also cause PCs and lead to diagnostic confusion.Objectives The aim of this study was to examine the natural history and clinicopathologic features of noncongenital, nonstaphylococcal PCs in children.Patients and methods Four children with nonstaphylococcal PCs were included in this study. A full history, clinical examination, relevant radiological and pathological findings, surgical intervention where relevant, and follow-up were analyzed.Results The cases described represent acquired PCs: one occurred after infarction following cardiac surgery, another was a subpleural pulmonary bleb of inflammatory origin, and the remaining two were post-traumatic pseudocysts. The inflammatory-process bleb and the postinfarction cysts presented with pneumothorax. The postinfarction and post-traumatic PCs responded to observation. The pulmonary bleb was excised.Conclusion Our understanding of the clinicopathologic features and pathogenesis of many types of acquired PCs is incomplete. We propose that PC formation has a basis in destruction of the distal airways of the lung. Damaged tissue may act as a valve, and cause air-trapping, which leads to PC formation. Cysts arising after infarction or after trauma usually resolve on observation. Subpleural blebs may require excision because of nonresolution and recurrence of pneumothorax

Effect of Matrix Composition on Steel Fiber Reinforced Concrete Properties.

Since the early 1960's, researchers have conducted experiments to improve the strength and deformation capacity of the concrete matrix by reinforcing it with various types of short cut steel fibers. While such investigations contributed to the underst and ing of the influence of fibers in improving wide spectrum of concrete mechanical properties, there is insufficient information about the effect of concrete matrix composition in determining the workability and improving the mechanical properties of steel fiber reinforced concrete (S.F.R.C.). The primary objectives of this study were to determine the influence of concrete mix composition on S.F.R.C. properties in both fresh and hardened state. Also, the percentage air voids and how it influences the strength of S.F.R.C. was determined. In addition, rational S.F.R.C. design procedure was established. Plain concrete mixes and S.F.R.C. mixes containing two types of steel fibers were made. Workability measurement were carried out using the VeBe Consistometer. Entrapped air was measured using the air pressure meter. Flexural strength and flexural toughness measurements were obtained using the third-point loading test. Compressive strength was determined for concrete prisms. For the range of aggregate maximum size used in this study ( 1/4" -1"), the ultimate flexural strength was found to be independent of maximum aggregate size. The fine aggregate needed in the mix is a function of volume and type of steel fibers used. Mixes made with medium and high fine aggregate content showed the best results with respect to workability and strength. The influence of fibers in increasing ultimate flexural strength was the greatest when low or medium water-cement ratio was used. The ultimate flexural strength was found to be approximately proportional to the fiber concentration in the concrete. The addition of fibers resulted in modest increase in S.F.R.C. compressive strength. The presence of air voids reduced both the compressive strength and the first crack flexural strength for mixes in which the fibers did not improve the first crack load. S.F.R.C. ultimate flexural strength was not affected by the presence of air voids.Ph.D.Civil engineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/160253/1/8502752.pd

Light and electron microscopy of eimeria magna perard, 1925 infecting the house Rabbit, Oryctolagus cuniculus from Saudi Arabia: II. Gamogony and Oocyst wall formation

Gamogony and oocyst wal1 formation of Eimeria magna Perard, 1925 were described by light and electron microscopy for the first time in the smal1 intestinal epithelium of experimental1y infected house rabbits, Oryctolagus cuniculus from three different regions in Saudi Arabia. Sequence of events started as sexual1y differentiated fourth and fifth generation merozoites transformed into micro- or macrogamonts at 125 h.p.i., where most of the apicomplexan organel1es have been disappeared gradual1y. Microgamonts were recognizable by the presence of peripheral1y arranged nuclei and the presence of one or two centrioles between each nucleus and the limiting membrane of the gamont, while macrogamonts were recognized by the presence of wal1-forming bodies of types I and II. Both microgametogenesis and macrogametogenesis had two phases, the growth and differentiation phases. Up to 150-250 microgametes were produced per microgamont, each had 2 flagel1a. Wal1-forming bodies II and lipid globules were the first cytoplasmic inclusions to appear characterizing the development of macrogamonts. Wal1-forming bodies II, which appeared at first, were osmiophilic and distributed homogenously. Wal1-forming bodies I, which appeared later, were smal1er & distributed peripheral to the walI-forming bodies II. Oocyst wal1 formation occurred by union of the wal1 forming bodies of each type together and resulting in the formation of the bilayered oocyst wall