Scar Evolution Research Articles

Illustrations of the Importance of Mass Wasting in the Evolution of Continental Margins: ABSTRACT

Side-looking sonar imagery and swath bathymetry from a variety of contemporary continental slopes all display erosional scars and debris aprons, illustrating the importance of mass wasting in the evolution of continental margins. The continental slopes examined include slopes fed directly from the fronts of ice sheets, slopes adjacent to continental shelves that were the sites of glacial outwash, slopes supplied exclusively by fluvial drainage, slopes at carbonate platforms, and slopes on accretionary prisms. Examples are drawn from the Atlantic Ocean, the Gulf of Mexico, and the Mediterranean Sea in both passive and active continental margin settings. The sonar imagery and bathymetry used in this study indicate that continental slopes in different tectonic and climatic environments show similar forms of mass wasting. However, in some cases the dominant mode of erosion and/or the overall degree of mass wasting appears to be distinct to particular sedimentary environments. Timing of both recent and older exhumed erosional surfaces identified in the imagery and in seismic reflection profiles is obtained by ground truth observations using submersibles, towed camera sleds, drilling, and coring. These observations suggest that eustatic fluctuations common to all the margins examined do not explain the range in magnitude and areal density ofmore » the observed mass wasting. More localized factors such as lithology, diagenesis, pore fluid conditions, sediment supply rates, and seismic ground motion appear to have a major influence in the evolution of erosional scars and their corresponding unconformities.« less

The role of scintigraphy in urinary tract infection

There is controversy regarding the role of radiological imaging for urinary tract infection (UTI). The "gold standard" has been the intravenous pyelogram (IVP). Yet, the IVP has a very limited value with only about 25% of children with pyelonephritis demonstrating abnormalities. Ultrasound (US) has recently been advocated as a replacement for the poorly sensitive and poorly specific IVP. However, comparative studies between US and IVP indicate only an equivalent sensitivity and specificity. Cortical scintigraphy with Technetium-99m glucoheptonate (99mTc GH) or 99mTc dimercaptosuccinic acid (99mTc DMSA) has also been advocated as a means of differentiating parenchymal (pyelonephritis) from nonparenchymal (lower UTI) involvement in UTI. The clinical presentation may be misleading especially in the infant and child in whom an elevated temperature, flank pain, shaking chills, or an elevated sedimentation rate are often lacking. The clinician attempts to localize the site of infection for it has a direct bearing upon the therapy. A collecting system infection can often be eradicated with a single oral dose of an appropriate antibiotic, whereas renal parenchymal involvement requires IV therapy for an extended interval. Cortical scintigraphy can localize the site of infection with a high degree of accuracy. Recent studies report a sensitivity of 86% and specificity of 81% of pyelonephritis. This is in contrast to the IVP with a sensitivity of only 24% and US with a sensitivity of only 42%. The scintigraphic appearance of parenchymal infection of the kidney is a spectrum of minimal to gross defects reflecting the degree of histologic involvement that spans from a mild infection to frank abscess. Cortical scintigraphy can be used to monitor the evolution of scarring following infection. Cortical scintigraphy with 99mTc DMSA or 99mTc GH is the method of choice for the initial evaluation of UTI. Not only does it have a very high sensitivity and specificity for differentiating parenchymal from collecting system disease, but it also provides an accurate quantitative measurement of function and in combination with radioiodinated orthoiodohippurate renography and Lasix (furosemide; Abbott Laboratories, North Chicago) diuresis will also differentiate significant obstruction from stasis. The use of radionuclide techniques opens new vistas for the investigation of UTI. Cortical scintigraphy should become the gold standard by which other technologies, therapy, and theoretical considerations of pyelonephritis are measured.

The Evolution of Scarring and Fibrosis following Penetrating Keratoplasty

The Evolution of Scarring and Fibrosis following Penetrating Keratoplasty

Follow-Up of Renal Morphology and Growth of 141 Children Operated for Vesicoureteral Reflux: A Retrospective Computerized Study

This study relates the postoperative evolution after ureterovesical reimplantation for vesicoureteral reflux (VUR) in 141 children who were ten years old or younger at the time of surgery. Renal growth and morphology were evaluated 2 and 5 years after surgery. We estimated renal growth by measuring the ratio of the bipolar parenchymal thickness to the total length of the kidney. We noticed that whatever the degree of reflux might have been, most of the kidneys partially or totally compensated for their growth failure. This growth resumption required many years to be completed. Surgical correction of VUR had favorable consequences on the radiologic aspect of pyelonephritic scars only on some of the kidneys: in these cases, the child's age appeared to be the only factor that had a statistical importance affecting the postoperative evolution of pyelonephritic scarring: the younger the children were at the time of surgery, the better the results obtained.

Follow-up of renal morphology and growth of 141 children operated for vesicoureteral reflux: A retrospective computerized study

This study relates the postoperative evolution after ureterovesical reimplantation for vesicoureteral reflux (VUR) in 141 children who were ten years old or younger at the time of surgery. Renal growth and morphology were evaluated 2 and 5 years after surgery. We estimated renal growth by measuring the ratio of the bipolar parenchymal thickness to the total length of the kidney. We noticed that whatever the degree of reflux might have been, most of the kidneys partially or totally compensated for their growth failure. This growth resumption required many years to be completed. Surgical correction of VUR had favorable consequences on the radiologic aspect of pyelonephritic scars only on some of the kidneys: in these cases, the child's age appeared to be the only factor that had a statistical importance affecting the postoperative evolution of pyelonephritic scarring: the younger the children were at the time of surgery, the better the results obtained.

Analysis of striae.

Striae proceed through stages quite similar to those in the evolution of scars. Most of the collagen bundles in the striae are highly stressed. Striae bear a striking resemblance to other human scar models in which newly synthesized connective tissue has been reorganized by tension. Unlike these other models, however, striae provide a readily available, easily obtained, plentiful source of tissue. We believe that striae can and should be used to further our understanding of the mechanical and biochemical factors responsible for the stress remodeling of connective tissue.