The effect of implant axial and torsional stiffness on fracture healing

A study was performed to compare the mechanical properties of healing transverse femoral osteotomies fixed with either (a) plates of high or low axial stiffness (compression or slotted plates) but equivalent bending and torsional stiffnesses, or (b) rods of high or low torsional stiffness (solid or slotted rods) but equivalent bending and axial stiffnesses. Compression and slotted plates were implanted contralaterally in one group of adult mongrel dogs and solid or slotted rods were implanted contralaterally in a second group as fixation for transverse osteotomies. We found that the compression-plated femora regained strength and stiffness earlier than the slotted-plated femora and healed with less callus formation. The femora fixed with rods healed with no significant differences in properties at any time interval. Also, the femora fixed with rods had mechanical properties close to those of the slotted-plated femora and lower than those of the compression-plated femora at the same time intervals. We concluded that contact compression caused the differences in the healing results and was more important than differences in torsional or axial rigidity of the implant.     

Fatal pulmonary bile embolism following acute acalculous cholecystitis

A 52-year-old man died during reoperation for bleeding after the development of acute postoperative acalculous cholecystitis. While the liver was being manipulated during surgery, the pulmonary artery diastolic pressure increased suddenly, cardiac output and blood pressure decreased, and soon afterward the patient had a cardiac arrest from which he could not be resuscitated. During resuscitative efforts, the maximum partial arterial oxygen pressure achieved was only 55 mm Hg despite 100% inspired oxygen. At autopsy, bile aggregates were found within necrotic liver parenchyma, portal and central vein branches, and numerous pulmonary arterioles and capillaries. The pulmonary arterial bile most likely resulted from embolization of inspissated hepatic bile aggregates during surgical manipulation.     

Food induced ("allergic") arthritis: inflammatory synovitis in rabbits

Progress in understanding rheumatoid (RA) and inflammatory arthritis has been limited in part because there has been no widely accepted animal model of naturally occurring human disease and because the clinical syndrome of RA may reflect the expression of multiple etiologies. We have considered that inflammatory joint disease may be induced and/or exacerbated by food related antigens. To facilitate our investigations, we studied inflammatory synovitis in rabbits induced by oral exposure to environmental antigens. In our preliminary experiments, we examined 9 Florida White, 30 New Zealand White, and 9 Old English rabbits. They were nourished with normal rabbit chow supplemented with either water or cow's milk beginning at age 7 to 26 weeks and observed for 81 to 204 days. Animals were then sacrificed. Histological sections of the knees were examined and graded in a blinded fashion for synovial cell hyperplasia, inflammation, and lymphoplasmocytic infiltration. In addition, serum levels of IgG antimilk, IgG antibovine serum albumin, IgG anticasein, and IgG-C3 complexes were quantified. We found no abnormalities among Florida White rabbits but observed histological synovitis in 53% of the milk fed New Zealand White (9/17), 40% of the water fed Old English (2/5), and all of the milk fed Old English rabbits (4/4) (p = 0.05, milk fed vs water fed animals). Milk fed animals had significantly (p less than 0.0005) greater levels of antibodies and complexes than water fed animals. Our data suggest that environmental antigens may be arthritogenic for some rabbit strains. These observations may provide an important model for the study of inflammatory joint disease analogous to oral, environmental antigen exposure in man.     

Serum magnesium concentrations after repetitive magnesium cathartic administration

Severe hypermagnesemia has been reported by several authors after multiple doses of magnesium-containing cathartic are administered during management of a toxic ingestion. To evaluate the frequency and magnitude of serum magnesium elevations after the use of repetitive magnesium catharsis, we prospectively evaluated 102 patients who received multiple doses of magnesium citrate as a part of treatment of an overdose. Commonly ingested substances for which repetitive cathartic was administered were tricyclic antidepressants in 47%, aspirin in 17%, and phenytoin in 10%. For each case, serial electrolytes, blood urea nitrogen, creatinine, calcium and magnesium were obtained. Mean initial serum magnesium concentration was 1.8 +/- .03 mEq/L. After a mean 960 mL of magnesium citrate (9.22 g magnesium), final mean serum magnesium concentration was 2.5 +/- .05 mEq/L. Forty-seven patients (47%) developed an elevated (greater than 2.4 mEq/L) serum magnesium concentration, with 12 greater than 3.0 mEq/L. No correlation was found between total quantity of magnesium citrate administered and the increment in serum magnesium concentration. Our data indicate that serum magnesium concentrations consistently rise after repetitive magnesium citrate use. However, the magnitude of this rise appears modest. The elevation in serum magnesium concentration does not correlate with the quantity of magnesium administered. We conclude that with close monitoring, repetitive magnesium citrate can be administered without inducing severe hypermagnesemia (serum magnesium concentration greater than 5.0 mEq/L).     

Postfiltration factor VIII and fibrinogen levels in cryoprecipitate stored at room temperature and at 1 to 6 degrees C

The 13th edition of the standards of the American Association of Blood Banks specified storage at 1 to 6 degrees C for cryoprecipitated anti-hemophilic factor (Cryo) administered up to 6 hours after thawing if the Cryo is used for factor VIII (FVIII) content (Standard J4.210). Previous editions specified room-temperature (RT) storage for up to 6 hours. Currently, the temperature specification has been deleted. There are few data addressing the optimal storage temperature and maximum storage time for FVIII and fibrinogen in thawed Cryo. Thirty bags of Cryo were assayed for FVIII and fibrinogen. Each bag was divided into two aliquots; one was stored at RT and the other at 1 to 6 degrees C. Assays were performed immediately after thawing (Base) and 6 and 24 hours after thawing, respectively. All samples were filtered through 200-mu blood component infusion sets before assay. Three hundred analyses were performed, 150 each for FVIII and fibrinogen by conventional clotting technique. Data were analyzed by using a paired t test. Cryo stored at 1 to 6 degrees C for 6 and 24 hours showed an FVIII loss of 35 percent (p less than 0.0001) and 63 percent (p less than 0.0001), respectively. Cryo stored at RT for 6 and 24 hours had an FVIII loss of 8 percent (p greater than 0.05) and 20 percent (p less than 0.0001). Cryo stored at 1 to 6 degrees C for 6 and 24 hours had a fibrinogen loss of 20 percent (p less than 0.0001) and 43 percent (p less than 0.0001). Cryo stored at RT for 6 hours had no fibrinogen loss and a 2 percent loss at 24 hours (p greater than 0.05). These preliminary data show a significant loss of FVIII and fibrinogen activity in Cryo stored at 1 to 6 degrees C and filtered before assay. The FVIII and fibrinogen activity at RT is clearly maintained up to 6 hours after thawing.     

Left main coronary anomaly arising from the right sinus of Valsalva-interarterial, septal, or a continuum?

Multidetector computed tomography angiography is increasingly used to visualize the coronary tree. It is emerging as the test of choice for the detection of anomalous coronary artery origin. It provides excellent spatial resolution and the ability to see the course of the coronary arteries and their proximity to adjacent structures. Invasive angiography has been the gold standard but does not allow the visualization of adjacent anatomic structures, which is crucial to correctly diagnosing the anomaly and determining the prognosis. We report a case of a 47-year-old woman with an anomalous left main coronary artery that arises from the right sinus of Valsalva where multidetector computed tomography angiography was key to the diagnosis and provided additional information that was not discernible from the invasive angiography.