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Biomedical subjects

A Radin

Publications and source records attributed to A Radin.

11 recordsLinked to original sources
PubMed1997

Percutaneous pinning of distal radius fractures: a biomechanical study.

Mechanical testing of extra-articular distal radius fractures stabilized with percutaneous pins was performed. Twelve fresh-frozen unembalmed radii stripped of all soft tissues were used. An osteotomy with dorsal comminution was made 2.5 cm proximal to the radial styloid. Three pin sizes and four pin configurations were used to fix the fracture, and the constructs were mechanically tested. Results show that at least a .062-inch pin was required for any significant changes in rigidity of the four pin configurations tested to be discerned. Cross-pinning with two radial styloid pins and placement of a pin from the ulnar corner of the radius as the most rigid construct in both torsion and cantilever bending.

Aged↗
PubMed1997

Percutaneous pinning of proximal humerus fractures: a biomechanical study.

Mechanical testing of two-part surgical neck fractures fixed with four different pin configurations was performed. Ten fresh, frozen, unembalmed humeri stripped of all soft tissues were used; the surgical neck was osteotomized perpendicular to the humerus long axis. Terminally threaded 2.5-mm AO pins were used to fix the fracture. Humeri then were tested in both torsion and bending on a custom-made jig using Instron 1331 to assess the rigidity of pinning constructs. In torsion, two lateral pin construct was significantly less rigid than all other pin configurations. The addition of an anterior pin to two lateral pins did not increase bending rigidity, but significantly increased torsional stiffness. The addition of two bicortical tuberosity pins or two bicortical tuberosity pins and one anterior pin to two lateral pins significantly increased rotational and bending rigidity. Results confirm clinical data, and the authors conclude that multiplanar pins are needed to augment torsional stiffness, and that the addition of two bicortical tuberosity pins enhances bending rigidity.

Biomechanical Phenomena↗
PubMed1997

Demonstration of rectosigmoid fistula dynamic scintigraphic peritoneography.

Intraperitoneal installation of chemotherapy through a Mediport implanted subcutaneously in the abdominal wall is used currently for treatment of peritoneal metastases from ovarian, gastric and colonic carcinoma. There is a variable incidence of complications due to the procedure reported in the literature. The main predisposing factor for these complications is the inhomogeneous distribution of the chemotherapeutic drugs within the peritoneal cavity. We report an unusual case of a rectosigmoid fistula that developed 6 wk following the insertion of a Bardport subcutaneously in the abdominal wall for intraperitoneal therapy. The fistula was clearly demonstrated by dynamic scintigraphic peritoneography. This is a new modification of scintigraphic peritoneography as practiced routinely. We endorse the previous recommendation that scintigraphic peritoneography be performed before every intraperitoneal installation of a chemotherapeutic drug or radiopharmaceutical to ensure the homogeneous distribution of the drugs and to prevent complications.

Aged↗
PubMed1985

Salmonella bacteremia in systemic lupus erythematosus. Eight-year experience at a municipal hospital.

Non-endemic Salmonella bacteremia tends to occur in patients with chronic disease. We reviewed all cases of Salmonella infection documented in adults at Bellevue Hospital during the years 1975-1982. Unexpectedly, the most frequent underlying disease found among bacteremic patients was systemic lupus erythematosus (SLE). Patients with SLE accounted for 6 of 30 Salmonella bacteremias as compared with 13 of 2,388 non-Salmonella gram-negative bacteremias. Salmonella was the single most frequent gram-negative isolate from the blood of SLE patients. All lupus patients with Salmonella infection were bacteremic. In contrast, isolates from blood represented only 23% of all Salmonella infections documented in the non-lupus population. Presentation was characterized by fever (greater than 103 degrees F) and abdominal pain. Four of the 6 patients were hypocomplementemic. All were receiving immunosuppressive therapy. We conclude that SLE patients in a municipal hospital setting are at increased risk for Salmonella sepsis. This should be considered when empiric antibiotic therapy is initiated.

Adolescent↗
PubMed1976

Independent effects of IgG and complement upon human polymorphonuclear leukocyte function.

Particle ingestion by polymorphonuclear leukocytes (PMN) is promoted by cell surface recognition and binding of fragments of the third component of complement (C3) and Fc regions of certain immunoglobulin (IgG) molecules. In order to determine the influence of these specific ligandsurface membrane interactions upon other PMN functions, we have employed nonphagocytosable particles (serum-treated Sepharose beads) coated with fragments of C3 and/or IgG, and have investigated whether these provide a sufficient stimulus for the metabolic changes and degranulation that ordinarly accompany phagocytosis by PMN. Sepharose 4B activates complement in fresh normal serum and consequently is coated with fragments of C3 (confirmed by immunoelectrophoretic evidence of factor B and C3 conversion and by immunofluorescence). Adsorbed IgG could be removed from serum-treated Sepharose by boiling in 2 M NaCl without significantly influencing bound complement. We have found that normal human PMN recognize and adhere to Sepharose beads coated with fragments of C3 and consequently are stimulated to increase their oxidative metabolism (measured as superoxide anion generation). This PMN response occurred in the absence of IgG but could be amplified if this immunoglobulin was also present on the bead surfaces. Both adherence and metabolic stimulation could be blocked by treatment of the beads with F(ab)2 anti-C3. In contrast to metabolic stimulation, degranulation (selective extracellular release of lysosomal constituents) was observed only when PMN encountered both C3 fragments and IgG on the beads. This response could be blocked by treating beads with either F(ab)2 anti-C3 or F(ab)2 anti-IgG. These results indicate that cell surface stimulation of PMN is not an "all or none" phenomenon and that certain vital functions of these cells may be mediated or modulated independently by immunoglobulins and complement.

Cell Adhesion↗
PubMed1975

Procollagen peptidase: its mode of action on the native substrate.

Procollagen peptidase was recovered from the medium of human and mouse fibroblast cultures by precipitation with ammonium sulfate. The test substrate for the in vitro enzymatic reaction was radioactively-labeled, disulfide-linked procollagen prepared from the medium of human fibroblast cultures. The enzymatic digests were analyzed by electrophoresis in polyacrylamide gets containing sodium dodecyl sulfate and urea. The human and mouse enzymes reacted with the substrate to generate the same intermediates and final products. Procollagen peptidase acts as an endopeptidase which cleaves each of the three procollagen chains in turn. The final products of the reaction are collagen and a three-chain, disulfide-linked fragment derived from the nonhelical aminoterminal residues of procollagen.

Animals↗
PubMedDate not supplied

Pullout properties of 3.5-mm AO/ASIF self-tapping and cortex screws in a uniform synthetic material and in canine bone.

OBJECTIVES--To compare the pullout properties of 3.5-mm AO/ASIF self-tapping screws (STS) to corresponding standard cortex screws (CS) in a uniform synthetic test material and in canine femoral bone. The influence of screw-insertion technique, test material, and test-material thickness were also assessed. STUDY DESIGN--In vitro experimental study. SAMPLE POPULATION--Two independent studies: a uniform synthetic test material and paired femurs from mature dogs. METHODS-Mechanical testing was performed in accordance with standards established by the American Society for Testing and Materials for determination of axial pullout strength of medical bone screws. Completely inserted STS, completely inserted CS, and incompletely inserted STS were tested in 3 groups of 10 test specimens each in 4.96-mm and 6.8-mm thick sheets of synthetic material. In the bone study, group 1 consisted of 24 completely inserted STS compared with 24 completely inserted CS, and group 2 consisted of 24 incompletely inserted STS versus 24 completely inserted CS. Comparisons were made between paired femurs at corresponding insertion sites. Pullout data were normalized, thereby eliminating the effect of test-material thickness on pullout properties. Mean values were compared using 2-way ANOVA. Statistical significance was set at P <.05. RESULTS--In both the 4.96-mm and 6.8-mm synthetic material, pullout testing of the completely inserted STS demonstrated significantly greater yield strength and ultimate strength than completely inserted CS. There was no significant difference between incompletely inserted STS and completely inserted STS. The 6.8-mm test material significantly increased yield strength and ultimate strength for all test groups compared with the 4.96-mm test material. In canine bone, there was no significant difference in yield strength of completely inserted STS and completely inserted CS. Yield strength of completely inserted STS and completely inserted CS were significantly greater than incompletely inserted STS. CONCLUSIONS--Pullout properties of completely inserted STS were significantly greater than corresponding CS in a uniform test material. In canine bone, the pullout strength of STS and CS were not different. Incomplete STS insertion resulted in an 18% reduction in holding power as compared with completely inserted CS and STS in canine bone. CLINICAL RELEVANCE--The length of STS used in canine bone should be such that the cutting flutes extend beyond the trans cortex to maximize pullout strength.

Animals↗
PubMedDate not supplied

Evidence of complement catabolism in acute pancreatitis.

Active proteolytic enzymes are released into the gland parenchyma and surrounding tissues during episodes of acute pancreatitis. Since complement components are potential substrates for active proteases and may be the source of biologically active peptides capable of mediating tissue injury, we have examined sera obtained from 12 patients during 13 episodes of acute pancreatitis for evidence of complement catabolism. In 8 of 13 acute phase sera, there were decreased levels of CH50, C3, C4, or some combination thereof as well as degradation products of C3 (revealed by crossed immunoelectrophoresis). In convalescent sera, levels of complement components were normal or elevated. Measurements of alpha1-antitrypsin, alpha2-macroglobulin, and trypsin inhibitory capacity failed to reveal evidence of protease-antiprotease imbalance. These findings provide evidence of complement catabolism in acute pancreatitis and suggest the possibility that activated complement components may play a role in the pathogenesis of some systemic pathologic changes which occur in this disease.

Acute Disease↗