Biomedical subjects
Publications and source records attributed to D R Benson.
The ability of nitrogenase-containing Frankia sp. strain CpI1 vesicles to regrow vegetative hyphae is demonstrated. Vesicles attached to hyphae in N2-fixing CpI1 cultures and sucrose gradient-isolated vesicles exhibited hyphal outgrowths when incubated in certain defined liquid media. Single or multiple hyphal extensions grew out from the vesicles.
The cases of 175 consecutive patients who had intraoperative autologous transfusion during revision total hip arthroplasty, an elective operation on the spine, repair of trauma to the spine, or open reduction of a fracture of the acetabulum were reviewed to evaluate the applicability of this technique in orthopaedic operations. A separate group of forty-one consecutive patients who had open reduction of a fracture of the acetabulum or the spine before the introduction of the autotransfuser was reviewed and compared with the group that had autotransfusion. An autologous blood predeposit program was used for twenty-five of fifty-two patients who had a procedure on the hip and for fifty-one of fifty-five patients who had an elective procedure on the spine. The mean rate of red blood-cell salvage using the autotransfuser was 60 per cent over-all. The mean transfusion requirements were significantly less (p less than 0.001) in all groups of patients in whom the autotransfuser was used. Use of the autotransfuser reduced the mean requirement for banked blood in patients who had a fracture of the acetabulum from 3.8 to 2.3 units per patient, and significantly reduced the mean need for banked blood in individuals who had trauma to the spine from 2.7 to 1.8 units per patient (p less than 0.01). The use of prebanked autologous blood further reduced the mean requirement for homologous blood from 2.4 to 0.8 unit per patient in those who had revision total hip arthroplasty (p less than 0.005), and from 3.6 to 0.4 unit per patient in those who had an elective procedure on the spine (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
A 14-year-old boy is presented with syringomyelia and a neuropathic sternoclavicular joint. Recognition of neuropathic arthropathy of the upper extremity is important when a massive, destructive joint lesion exists in a patient with syringomyelia.
Biological N2 fixation is performed most effectively by prokaryotic diazotrophs when in mutualistic symbioses with higher plants. The most intensively studied N2-fixing symbioses involve leguminous plants and rhizobia. However, Frankia actinomycetes have attracted attention recently because they form root nodules on a broad range of non-legumes and because such nodules fix N2 as effectively as rhizobial nodules. Since the Frankia symbiosis results from an actinomycetic invasion of plant roots, it has been termed the 'actinorhizal symbiosis'.
There is much controversy as to the appropriate treatment of unstable thoracolumbar fractures. If surgery is decided upon, this article suggests a plan to accomplish the reduction of the fracture and decompression of the neural elements. The fractures are divided into compression injuries, seat belt injuries, fracture-dislocations, and burst fractures. In each case the goal is to realign and stabilize the spine and allow adequate room for the spinal cord or the cauda equina. A burst fracture requires the most careful planning. Some decompression can be accomplished by distraction alone but impaction of the fragments posteriorly or removal of the fragments anteriorly may be required. The experience at the author's university has demonstrated that by using these techniques, the preoperative neurocanal compromise can be significantly improved over those series using posterior distraction alone. If canal compromise cannot be accomplished posteriorly, then anterior surgery is required.
Frankia sp. strain CpI1 has two glutamine synthetases. Glutamine synthetase I (GSI) is present during growth on ammonium or N(2) and is similar to classical prokaryotic glutamine synthetases. Gel-filtration chromatography gave a molecular weight estimate of about 680,000 for the GSI holoenzyme, and denaturing polyacrylamide gel electrophoresis yielded a subunit molecular weight of about 59,000, indicating that GSI is most likely a dodecamer. GSI is regulated by adenylylation, as shown by the presence of two spots on two-dimensional polyacrylamide gel electrophoresis and by its behavior during treatment with snake venom phosphodiesterase. GSII is derepressed during nitrogen starvation and accounts for about 95% of the glutamine synthetase activity in nitrogen-starved cells. It is heat-labile and has a subunit molecular weight of about 43,000. Frankia GSII is similar to GSII enzymes found in all but one member of the Rhizobiaceae analyzed to date. The presence of a second glutamine synthetase in Frankia lends support to the proposal that symbiotic organisms have unique modes of nitrogen nutrition but reopens questions about the origins and uniqueness of GSII genes in members of the Rhizobiaceae.
A prospective study to investigate changes in the rib hump or rib deformity after correction of the lateral curvature in adolescent idiopathic scoliosis is reported. The operative treatment for 47 patients was by a Harrington distraction rod and posterior fusion. Before operation and at follow-up, measurements of the Cobb angle, of vertebral rotation, and of the rib deformity were taken. Despite operative correction of the lateral curve, there was a progression of the rib deformity in 64% of the cases after four years. Correction of the lateral curve may thus have no effect on vertebral rotation and cannot be guaranteed to effect a permanent reduction of the rib hump.
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The etiology of idiopathic scoliosis remains unknown. Certain growth characteristics have been identified but they have not led to any conclusions as to the cause. Scoliosis is a progressive disease, even in adulthood, and can lead to significant disability if large curves are left untreated. Conservative treatment remains in the realm of braces as electrostimulation has not proven its worth. The techniques of spinal surgery and instrumentation have taken the largest leaps in the past decade. Technically, difficult anterior and posterior instrumentation and fusion are more safely done when the spinal cord is monitored. The future is bright and may open even more vistas in the next decade. Prophecies are made as to what tomorrow will bring.
Under N2-fixing conditions in aerobic culture and in symbiosis, frankiae produce spherical, multicellular structures that have been called vesicles. The vesicles have been proposed as the site of nitrogen fixation. We isolated vesicles by using density centrifugation in a single-step sucrose gradient. Vesicles migrated out of 50% (wt/vol) sucrose and banded at the 40 to 50% sucrose interface; they were intact, as assessed by transmission electron microscopy, and were free of hyphal contamination. Specific activities of nitrogenase in vesicles prepared anaerobically were up to 100-fold greater than the specific activity of the largely hyphal pellet, depending on the recovery of vesicles. All of the activity in the pellet could be accounted for by the number of vesicles present in the pellet. Glutamine synthetase activity in crude extracts of vesicles was extremely low.
Growth in volume of the anulus fibrosus (AF) and nucleus pulposus (NP) was quantified using serial histological sections of human and kitten fetuses. Fetal intervertebral discs were studied that had clearly outlined AF and NP. Regression equations were calculated and graphs plotted by microcomputer. An increase in surface areas of these intervertebral structures was also recorded; however, volume was a better indicator of relative growth than was surface area. The AF volume of the fetal human increased more in proportion to the intervertebral disc than it did for the fetal kittens. There was significantly slower growth of the human NP compared to the kitten NP when related to the total intervertebral disc. The analysis for each species was done separately. Comparisons of the growth relationships of humans and kittens for the AF and NP were related to crown-rump length as the independent variable, and were different at the p less than or equal to 0.01 level of significance. The thoracic intervertebral discs were emphasized due to species-specific differential growth of the AF. The intercapital ligament (IC) was separated from mesenchyme over the dorsal surface of the kitten AF, and this affected the relationships of AF and NP volumes when compared to humans. Use of human histological sections is essential in the study of differential growth of the human vertebral column because fetal kittens have an IC that affects relative growth of both AF and NP.
An anomalous (butterfly) eleventh thoracic vertebra in a fetus of 63 mm greatest length is described and graphic reconstructions (together with normal controls) are provided. The cartilaginous hemicentra are separated by disc-like material. Cartilaginous bars to adjacent vertebrae are present. The neural arch is complete. The notochord is not duplicated. Only one comparable case in the embryonic period has been described previously. After a discussion of cleft vertebrae in the human and in experimental animals, a developmental timetable of the appearance of several vertebral anomalies is provided. The sensitive period for butterfly vertebrae, depending on the mode of origin, seems to be 3-6 postovulatory weeks. More severe anomalies, such as the split notochord syndrome, appear earlier. It is concluded that most of the vertebral anomalies discussed arise during the embryonic period proper, although the timing of a few, such as spina bifida occulta, extends into the early fetal period.
Developmental features of thoracic intervertrebral discs and their association in the adult with other vertebral structures were investigated in four species. The human anulus fibrosus, nucleus pulposus, and intra-articular ligaments were compared to those of the fetal rhesus monkey, mouse, and kitten. Photomicrographs of transverse sections of intervertebral discs document the presence of intra-articular ligaments in fetuses of these four species. Both transverse and sagittal sections of kittens were used to identify the intercapital ligament as it differentiated from the dorsal part of the intra-articular ligament. Relatively frequent dorsal herniation of the thoracic nucleus pulposus in humans may be due to the vestigial nature of the human intra-articular ligament. Quadrupeds have well-developed intra-articular ligaments, which explains anatomically the paucity of dorsal protrusions of the nucleus pulposus into the vertebral canal in the thoracic region of the cat and mouse when compared to the human. The intra-articular ligament was closely associated with the developing prenatal mammalian intervertebral disc in the four species studied, and this relationship and its surgical importance are described.
Fifteen Frankia strains from five different plant species were analyzed by two-dimensional polyacryl-amide gel electrophoresis to determine their relatedness by comparing the polypeptide patterns obtained. Three major subgroups (A, C, and D) were found in the Alnus-Comptonia-Myrica cross-inoculation group. An isolate from Purshia tridentata had a unique protein pattern and represents a distinct group of frankiae. Members of group A were isolated from root nodules of Alnus incana subsp. rugosa and Alnus viridis subsp. crispa. Group C organisms were from A. incana subsp. rugosa and Comptonia peregrina nodules, and group D organisms were from A. incana subsp. rugosa, A. viridis subsp. cripsa, and Myrica pensylvanica root nodules. Isolates from each gel group were obtained at several widely separated geographical locations. The results indicate that two-dimensional polyacrylamide gel electrophoresis is useful for identifying Frankia isolates.
We describe an NH4+-specific transport system in the N2-fixing symbiotic actinomycete Frankia sp. strain CpI1. [14C]methylammonium was used as an NH4+ analog. No specific transport process was detected when cells were grown on high concentrations of NH4+. A transport system with a high affinity for CH3NH3+ was synthesized after 3 to 4 h of nitrogen starvation. Methylammonium transport was not significantly inhibited by a variety of amino acids, primary amines, and polyamines. Ammonium completely eliminated CH3NH3+ transport. The Km for CH3NH3+ transport was around 2 +/- 1.8 microM with a Vmax of 4 to 5 nmol/min per mg of protein. The electron transport inhibitors cyanide and azide eliminated uptake, as did the uncoupler carbonyl cyanide-m-chlorophenylhydrazone. The sulfydryl reagent p-chloromercuribenzoic acid and the heavy metal thallium also inhibited uptake, suggesting the presence of an NH4+-specific permease. Concentration of CH3NH3+ across the membrane was demonstrated by conducting uptakes at low temperature to slow the metabolism of CH3NH3+ by glutamine synthetase. At 7 degrees C most of the label was concentrated inside the cells in a form that could be chased from the cells by adding excess NH4+ to the medium. At 30 degrees C most of the label was present as an impermeant metabolite. Thin-layer chromatography of cell extracts confirmed that the radioactivity inside the cells was mainly in the form of CH3NH3+ at 7 degrees C but was present as an unidentified metabolite at 30 degrees C. These studies demonstrate that Frankia sp. strain CpI1 has a high-affinity NH4+ transport system that is synthesized in response to NH4+ starvation.
The tibia from six-week old chickens that develop idiopathic scoliosis were studied with stress relaxation experiments and torsional strength testing. Most parameters observed did not show any significant differences between tibias obtained from chickens with scoliosis and tibias from the control birds; however, the rate of stress relaxation of the tibia from the birds with scoliosis was minimally increased over the controls. There were no significant differences noted in ultimate torsional strength, maximum angular deformity or modulae of torsional rigidity of the tibias from scoliotic chickens when compared to tibias from control chickens.
A double-blind prospective study was done to assess the benefit of delaying closure of the wounds associated with open fractures. An additional double-blind study compared the effectiveness of clindamycin versus cefazolin for prophylactic antibiotic coverage. Quantitative cultures of the wounds were accomplished at the time of debridement and again at the time of closure if the wound was not closed initially. Almost half of the wounds were contaminated (46%) at the time of debridement, although the incidence of wound infection was low (6.5%). Gram-negative organisms resistant to the prophylactic antibiotic were recovered initially only eight times, but four of these (50%) became infected. The contaminating organisms in each case were present in high concentration (greater than 10(5) CFU/gm of tissue) at initial culture. The time of wound closure, cefazolin versus clindamycin, and internal fixation of the fracture were not followed by significant differences in the development of clinical infection in this series.
A simple procedure, based on the rapid filtration and washing of Frankia vesicle clusters, was devised for the isolation of Frankia strains from alder actinorhizal root nodules. Of 46 Alnus incana subsp. rugosa nodules prepared, 42 yielded isolates. A simple medium containing mineral salts, Casamino Acids, and sodium pyruvate proved to be the most effective for isolation. In general, colonies appeared 6 to 20 days after inoculation. On the basis of hyphal morphology, two distinct types of Frankia strains were characterized. Randomly selected isolates were tested for infectivity, and all formed root nodules on A. glutinosa. Because of its simplicity and efficiency, the procedure is an improved method for the study of Frankia diversity in alder root nodules.