Biomedical subjects
Publications and source records attributed to R A Fischer.
An elderly male patient with Pseudomonas denitrificans bacteremia and meningitis is described. The antimicrobial susceptibility and minimum criteria necessary for the identification of this unusual and rare human pathogen are discussed.
Conditioned medium prepared from human placenta tissue stimulates in vitro colony formation by mouse and human marrow cells. At least two types of colony-stimulating activities are found and can be separated by isoelectrofocusing. The first type of colony-stimulating factor (CSF) shows heterogeneity on isoelectrofocusing with pI in the range of 3.6-4.7. It has been purified 10(5)-fold by hydroxylapatite chromatography, preparative isoelectrofocusing, gel filtration, polyacrylamide gel isoelectrofocusing, and electrophoresis to a specific activity of 7.5 X 10(7) units/mg. The purified CSF shows a single band on microgel electrophoresis and stimulates mostly mouse macrophage colony formation. It has a molecular weight of 41 000 as determined by gel filtration and is sensitive to proteolytic enzyme digestion and periodate oxidation. Treatment with neuraminidase is without effect on activity. It is stable at pH 5-10 and 60 degrees C for 30 min. The second type of CSF appears as a single activity peak on isoelectrofocusing with a pI of 5.7. The molecular weight is calculated to be 27 000 from gel filtration. It is very sensitive to trypsin and periodate but inert to neuraminidase or mercaptoethanol treatment. It is stable at neutral pH but labile at 60 degrees C for 30 min. The purified CSF stimulates predominantly granulocytic colony formation from human marrow cells.
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Granular cell myoblastoma is an uncommon benign tumor. The diagnosis is rarely suspected preoperatively, and the clinician is frequently baffled or frightened by an unfamiliar diagnosis. Twenty-eight patients with the diagnosis of granular cell myoblastoma presented for treatment at Richmond Eye and Ear Hospital and the Medical College of Virginia Hospitals between January 1, 1952, and December 31, 1974. The authors believe that this is one of the largest series of cases reported in the world literature. The tumor presents most often in the fourth decade of life and about equally in the sexes. Of interest is the nearly 5:1 predominance in the Negro race compared to the Caucasian race.
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With isolated epidermal strips of Vicia faba, the intensity of potassium-staining in the guard cells of stomata was calibrated against the uptake of radioactively labeled potassium. By using this calibration, the quantity of potassium that had accumulated in the guard cells, as stomata of leaves of Vicia open in the light, was estimated. Results support the hypothesis that in leaves, as well as in isolated epidermal strips, potassium and an accompanying anion comprise the major, osmotically active solutes in the guard cells of open stomata.
Stomata in isolated epidermal strips open in response to light plus air free of carbon dioxide when the strips are floated on potassium chloride solutions of low concentrations. This opening depends on the stimulation of active accumulation of potassium in quantities sufficient to account for the observed changes in solute potential of the guard cells.
This paper reports a consistent and large opening response to light + CO(2)-free air in living stomata of isolated epidermal strips of Vicia faba. The response was compared to that of non-isolated stomata in leaf discs floating on water; stomatal apertures, guard cell solute potentials and starch contents were similar in the 2 situations. To obtain such stomatal behavior, it was necessary to float epidermal strips on dilute KCl solutions. This suggests that solute uptake is necessary for stomatal opening.The demonstration of normal stomatal behavior in isolated epidermal strips provides a very useful system in which to investigate the mechanism of stomatal opening. It was possible to show independent responses in stomatal aperture to light and to CO(2)-free air.
The stimulation by KCl of stomatal opening in isolated epidermal strips of Vicia faba was examined. In dark + normal air the opening response was maximal at 100 mm KCl while in light + CO(2)-free air it was maximal at about 10 mm KCl. CO(2)-free air was more influential than light in reducing the KCl concentration required for maximal opening. K(+) was essential while Cl(-) seemed to be of secondary importance in these processes.The use of (86)Rb(+) as a tracer for K(+) showed that the increase in stomatal aperture under various conditions was well correlated with K(+) uptake. The estimated amount of K(+) taken up by guard cells, along with a counter ion, was sufficient to account for the changes in solute potential associated with opening. It is suggested that the absorption of extracellular solutes, such as K(+), may be the primary mechanism of stomatal opening. Both opening and K(+) absorption are stimulated by light + CO(2)-free air.The increase in stomatal aperture was also well correlated with the decrease in stainable starch in guard cells under all conditions. It is suggested that this is a secondary change, although perhaps closely linked to K(+) absorption.
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To determine the effects of age, sex, and arm dominance on shoulder range of motion, we measured active and passive forward elevation, abduction, internal and external rotation at 90 degrees of abduction, external rotation with the arm adducted, and extension bilaterally in 280 subjects ranging in age from 4 to 70 years. Linear regression analyses were performed for all motions except forward elevation. This motion, which showed a nonlinear pattern of decline with age, was evaluated with 3-way analysis of variance. Shoulder range of motion decreased with age for all measured motions with the exception of internal rotation, which increased with age. Female subjects had a significantly greater range of motion than male subjects for all motions measured. Dominant arms displayed significantly greater external rotation than nondominant, regardless of whether the arm was abducted or adducted at the time of measurement. However, nondominant shoulders demonstrated significantly greater internal rotation and extension than dominant. No significant differences were found between dominant and nondominant sides for forward elevation or abduction.
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PURPOSE: The purpose of this work was to characterize the MR features of post-traumatic osteolysis of the distal clavicle in patients who have sustained a previous separation of the ipsilateral acromioclavicular (AC) joint. METHOD: We studied eight male patients (mean age 25 years) with intractable pain in the AC joint after sustaining a traumatic joint separation. With use of the Rockwood classification, the separations were classified as Type 1 in one patient, Type 2 in two patients, and Type 3 in five patients. The MR studies were evaluated for periarticular soft tissue swelling, cortical irregularity defined as thinning or absence of portions of the cortex in the acromial and clavicular articular surfaces, hypertrophic osseous changes, periostitis, bone marrow edema, periarticular cyst-like changes, and joint space widening exceeding 6 mm. Radiographs were evaluated independently of the MR studies. Osteolysis of the distal clavicle was confirmed pathologically in seven patients and with surgery in one patient. RESULTS: The incidence of osteolysis in patients who have had a previous AC joint separation was estimated to be approximately 6%. Observations on MRI included soft tissue swelling, bone marrow edema in the distal clavicle, and cortical irregularity associated with periarticular cyst-like erosions in eight patients, joint space widening in six patients, clavicular periostitis in three patients, and marrow edema in the cromion in five patients. Only one patient had osteophyte formation. Radiographic observations of periarticular soft tissue swelling, osteopenia of the distal clavicle, articular erosions, and joint space widening allowed diagnosis in only four patients prospectively. CONCLUSION: The MR features of posttraumatic osteolysis are characteristic of this process. We advocate the use of MRI in patients with chronic AC joint pain who have had a prior AC joint dislocation, particularly if follow-up radiographs are nonspecific, equivocal, or do not indicate the presence of secondary osteoarthritis.
The rehabilitation of knee injuries involving the anterior cruciate ligament (ACL) is controversial. This paper describes strain in the normal and reconstructed ACL during a series of passive and active tests of knee flexion with and without varus, valgus, and axial rotation torques on the tibia. Strain in the human knee ACL was significantly different depending on whether the knee flexion angle was changed passively or via simulated quadriceps contraction. The knee joint capsule was found to be important for strain protection of the ACL. Quadriceps activity did not strain the normal or reconstructed ACL when the knee was flexed beyond 60 degrees, but significantly strained the tissue from 0 to 45 degrees of knee flexion. Immobilization may not protect the ACL if isometric quadriceps contractions are allowed to occur. Properly placed reconstructions exhibited strain behavior which closely followed the anteromedial band of the ACL.
Strain in the human knee medial collateral ligament (MCL) was measured in cadavers with a Hall effect strain transducer during normal passive knee flexion, as well as knee flexion accompanied by applied external tibial rotation and valgus torques. In an attempt to determine the contribution of the posterior oblique ligament (POL) to the strain behavior of the MCL, the POL was systematically separated from the MCL and changes in strain in the MCL were observed. These changes in strain were mild and variable, except in the one knee which was later found to be lacking an anterior cruciate ligament. In that particular knee, strain in the MCL increased up to 9.97% under the influence of a valgus torque once the POL fibers had been separated from the MCL. Anatomical dissection and transillumination techniques of the MCL/POL complex demonstrated definite ligament fibers connecting the MCL to the POL. The results demonstrate an intimate anatomical relationship between the POL and MCL. However, the POL and MCL appear to work independently from each other according to our test method.
We studied the relationship between anterior-posterior knee laxity and the structural properties of autogenous patellar tendon grafts used to replace the anterior cruciate ligaments in dogs 1 year after reconstruction. At 30 degrees (full extension for the dog), 60 degrees, and 90 degrees of flexion a significant inverse correlation was found between anterior-posterior knee laxity and the ultimate failure strength of the graft. Likewise, at 60 degrees and 90 degrees of flexion a significant inverse correlation was found between knee laxity and the linear stiffness of the graft. In all cases, as knee laxity increased, the ultimate failure load and linear stiffness values of the graft were found to decrease. There was also a significant increase in anterior-posterior knee laxity of the reconstructed knees (produced by an increase in anterior translation of the tibia relative to the femur) compared with the contralateral control knee. The group of dogs that underwent a sham operation without reconstruction of the anterior cruciate ligament had no change in anterior-posterior knee laxity or the structural properties of the anterior cruciate ligament. The clinical significance of this investigation is that knee laxity measurements demonstrating an increase in anterior translation of the tibia relative to the femur during graft healing may indicate that the graft has weakened and reduced structural properties.
Ten consecutive patients with isolated atraumatic osteolysis of the distal clavicle who had failed results with conservative treatment were treated with arthroscopic resection of the involved distal clavicle (average, 4.5 mm). All patients were men with an average age of 30.4 years, had unilateral involvement, and were considered aggressive amateur to elite weight lifters or bodybuilders. Postoperative symptoms consisted of pain at the incision and discomfort from extravasation of the irrigation fluid. At an average followup of 18.7 months, all patients had returned to their sport (average, 3.2 days) and to their preoperative weight training program (average, 9.1 days). They continued to be asymptomatic throughout the follow-up period and were able to increase both their training volume and strength from preoperative levels. Limited arthroscopic resection of the distal clavicle for isolated atraumatic osteolysis is a viable alternative for the weight lifter or bodybuilder. The ability to continue training without significant interruption as well as a more acceptable cosmetic appearance are benefits for these patients. Limited arthroscopic resection of the distal clavicle may be sufficient for this entity in this patient population, rather than the 1 to 2 cm previously reported. A sport-specific functional outcome questionnaire has been developed for this patient population.