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Biomedical subjects

R W Hendrix

Publications and source records attributed to R W Hendrix.

At least 73 records · Page 4Linked to original sources
PubMed1987

Evaluation of ectopic bone by CT.

The CT appearance of ectopic bone and its maturation in 25 patients were correlated with the findings on radiographs and bone scans. Ossification progressed from an early appearance of soft-tissue density of lower attenuation than muscle to a calcific density paralleling radiographic and scintigraphic evidence of bone formation. Persistent unossified, low-density soft tissue was detected adjacent to mineralized areas of ectopic bone in 14 patients up to 16 years after neurologic injury, often with bone-scan evidence of maturity of the ectopic bone. This soft tissue most likely corresponds to immature, unossified connective tissue, which may have a potential for ossification. Detection of areas of soft-tissue density by CT and their avoidance during surgical resection of an ankylosing mass of ectopic bone may reduce intraoperative hemorrhage and postoperative ectopic bone recurrence.

Adolescent↗
PubMed1985

Consensus sequence for Escherichia coli heat shock gene promoters.

We have identified promoters for the Escherichia coli heat shock operons dnaK and groE and the gene encoding heat shock protein C62.5. Transcription from each promoter is heat-inducible in vivo, and each is recognized in vitro by RNA polymerase containing sigma 32, the sigma factor encoded by rpoH (htpR) but not by RNA polymerase containing sigma 70. We compared the sequences of the heat shock promoters and propose a consensus promoter sequence, having T-N-t-C-N-C-c-C-T-T-G-A-A in the -35 region and C-C-C-C-A-T-t-T-a in the -10 region. These sequences differ from the consensus sequence recognized by holoenzyme containing sigma 70, the major sigma in E. coli. We suggest that the accumulated consensus sequences of promoters recognized by alternate forms of holoenzyme are compatible with a model in which sigma recognizes only the -10 region of the promoter.

Base Sequence↗
PubMed1985

Surgical fusion of the posttraumatic spine: a radiologic assessment.

Radiological assessment of surgical fusion of fractures and dislocations of the cervical, thoracic, and lumbar spine are an integral part of management of spinal cord injury patients. A meaningful assessment of such fusions can be done properly only when there is adequate knowledge of the types of surgical fusions, the biological material used, and metallic devices applied. Early surgical reduction and internal fixation of the traumatized spine facilitate rapid restoration of spinal alignment, make nursing care less difficult, and sometimes lead toward improvement of neurological function. Complications can occur in all types of surgical fusions. They can affect the fusion material, the metallic device, or the alignment of the spine. Most of those complications are radiologically detected.

Bone Nails↗
PubMed1984

Length determination in bacteriophage lambda tails.

We have isolated viable mutants of bacteriophage lambda that have in-frame deletions in gene H, which codes for a minor tail protein. They produce correspondingly smaller but active gene H protein products and assemble shorter-tailed phage particles. The deficiency in tail length for each mutant corresponds to the calculated shortening of the gene H protein caused by the deletion. These results show that the H protein determines tail length and argue strongly for a scheme in which the H protein is a ruler or template that measures length during tail assembly.

Bacteriophage lambda↗
PubMed1984

Carpometacarpal dislocations.

Dislocations at the carpometacarpal joints are uncommon and can be overlooked due to the subtle nature of the radiographic findings. The diagnosis requires a proper understanding of the normal radiographic anatomy of the carpometacarpal joints. To aid in our understanding of the injury, anatomic dissections of the hand were performed. From these, we drew several conclusions about the mechanism of injury. Diagnostic criteria were then developed and applied in the review of a series of CMC dislocations. The incidence and diagnostic characteristics are presented. A systematic approach emphasizing the posteroanterior view and utilization of the parallel "M", principles of parallelism, symmetry, overlapping articular surfaces, and a distinct cortical rim are presented.

Adolescent↗
PubMed1983

Domain structure and quaternary organization of the bacteriophage P22 Erf protein.

The structure and activities of the recombination-promoting P22 Erf protein were examined in vitro. Treatment of the protein with elastase produces a stable amino-terminal fragment, consisting of amino acid residues 1 to (approximately) 136. We have purified this fragment, designated fragment B, to apparent homogeneity by gel filtration chromatography. Fragment B retains the oligomeric structure and single-stranded DNA binding specificity of intact Erf. It differs, however, in lacking the ability of intact Erf to bind single-stranded DNA into large aggregates following mild heat treatment of the protein. In addition, its binding to DNA may be weaker than that of intact Erf. Intact Erf sediments through a sucrose gradient as a discrete species with an apparent S20,w of approximately 11 X 7 S. Its sedimentation behavior is affected little, if at all, by concentration. Fragment B also sediments as a discrete species at approximately 10 X 4 S. In the electron microscope, intact Erf appears as rings, with 10 to 14 small projecting structures resembling the teeth of a gear. Fragment B is similar, except that it appears to lack the peripheral structures. From these observations, we conclude that Erf consists of at least two structurally and functionally distinct domains, and that it has a discrete ring-like oligomeric structure.

Amino Acid Sequence↗
PubMed1983

Proteolytic processing of phage lambda tail protein gpH: timing of the cleavage.

We describe a method for the rapid partial purification of intermediate structures of phage lambda tail assembly, using formaldehyde-fixed Escherichia coli cells to precipitate tail-related structures. The purification depends on the specific interaction between the E. coli lambda receptor protein and lambda tail protein gpJ. Protein compositions of tail assembly intermediates were analyzed to determine when in the assembly sequence the minor tail protein gpH is cleaved. gpH joins the tail precursor structure early in the pathway, during assembly of the initiator (a structure that becomes the tail tip). However, gpH is not cleaved until after initiator assembly is complete and after the tail shaft has polymerized onto the initiator. These results suggest that each gpH molecule is extended along the length of the tail. Our results also appear to eliminate an ambiguity in the tail assembly pathway determined by earlier experiments: we argue that gene G acts between genes H and M.

Bacterial Outer Membrane Proteins↗
PubMed1983

Role of gene T in phage lambda tail assembly.

We have studied the phenotype of a heat-sensitive mutation that defines lambda tail gene T. Induction and growth at the nonpermissive temperature of a lambda Tts40 prophage results in production of morphologically normal but biologically inactive tails, which can be activated in vitro by lysates supplying the products of genes T, U, and Z. Thus, gene T acts between genes V and U in the tail assembly pathway or immediately after the completion of tail shaft polymerization. lambda Tts40 lysates also contain a substantial number of morphologically normal phage particles which are deficient in cleavage of the minor tail protein gpH. This result is consistent with the fact that gpH cleavage normally occurs later in the assembly pathway than the time found for gene T action. Purified lambda Tts40 virions that were produced at the permissive temperature are normal with respect to gpH cleavage. However, they are more sensitive to heat inactivation than are wild-type virions, suggesting that the T gene product is in the virion. At the permissive temperature, the mutant protein made by lambda Tts40 is active in vivo even if it has been synthesized at the nonpermissive temperature.

Bacteriophage lambda↗
PubMed1983

Computed tomography of tuberculous osteomyelitis of the pubis.

Computed tomographic findings in a case of isolated pubic tuberculous osteomyelitis with an associated tuberculous soft tissue abscess are described. Computed tomographic findings include local bony erosion and destruction, as well as an associated peripherally enhancing soft tissue mass.

Humans↗
PubMed1983

Arthrography after total hip arthroplasty: a modified technique used in the diagnosis of pain.

The results of plain film radiography and arthrography in diagnosing loosening of a prosthetic component after total hip arthroplasty were correlated with surgical findings in 31 patients who required surgery because of hip pain. The accuracy of arthrography in diagnosing component loosening using 5 ml of contrast material was 51%, and the accuracy of plain radiography was 69%. An accuracy of 92% was achieved using a modified arthrographic technique in which the pressure in the joint was recorded after injection of contrast material and while the patient walked to ensure that it was comparable with the pressure that caused the patient's pain prior to the study. Three per cent of the arthrographic studies using this technique were false negative and 5% were false positive.

Acetabulum↗
PubMed1983

Systematic approach to identifying fourth and fifth carpometacarpal joint dislocations.

Dislocations of the carpometacarpal (CMC) joints are rare injuries which often have subtle radiographic findings that may be overlooked. A systematic approach for evaluation of the carpometacarpal joints is developed from analyzing the radiographic findings in 17 cases of CMC dislocations at the fourth and fifth CMC joints. Principles of parallelism, symmetry, overlapping articular surfaces, indistinct cortical rim, and parallel M lines are used in this evaluation. Ten patients had combined fourth and fifth CMC joint dislocations and seven had solitary dislocations at the fifth CMC joint. Most of these CMC dislocations are dorsal (71%). In combined fourth and fifth CMC joint dislocations, loss of parallelism and symmetry is observed at the fourth CMC joint with overlap identified primarily at the fifth CMC joint. Fracture of the fourth metacarpal base is often an associated injury. In solitary fifth CMC dislocations, slight ulnar offset of the fifth metacarpal on the hamate is the most consistent finding in association with loss of parallelism, symmetry, and overlap. Fracture of the radial margin of the fifth metacarpal base is often observed with solitary fifth CMC joint dislocations. A systematic approach and establishing the diagnosis from standard radiographic views is emphasized.

Adult↗
PubMed1983

Thoracic and lumbar spine fusion: postoperative radiologic evaluation.

A retrospective review of 206 consecutive thoracic and lumbar fusions revealed a variety of surgical procedures performed for instability and malalignment after severe trauma. Stabilization procedures included insertion of 103 Harrington distraction and 15 Harrington compression rods, 84 Weiss spings, six Luque rods, and 10 miscellaneous plates and wires as single or multiple devices in combination with anterior and/or posterior fusions. Complications of surgical fusion included nine unhooked rods, six fatigue fractures of rods and springs, five overdistractions of vertebrae, four cases of severe kyphosis, and two failures of reduction. A meaningful postoperative radiologic evaluation can be accomplished only when indications for surgical techniques, their radiologic appearance, and possible complications are known.

Adolescent↗
PubMed1982

Bone studies in patients on prolonged systemic corticosteroid therapy for asthma.

Cortical thickness of the second metacarpal bone and lumbar spine fractures were determined radiographically in twenty-one caucasian corticosteroid-dependent asthmatics (mean age, 61.2 years; range 47-73 years). The mean number of prednisone years per patient of continuous corticosteroid treatment averages 9.7 (range 5.0-21.5 years), and the mean accumulated dose of prednisone was 46.7 g (range 10.7-160 g). Thirteen of twenty-one (61.9%) patients had cortical thickness between 1 and 2 standard deviations (s.d.) below the age- and sex-specific mean for normals, but only four (19%) patients fell below 2 s.d. Although the study indicated decreased cortical thickness in the prednisone-treated group, in only one (4.8%) patient were vertebral fractures present, an incidence not unexpected in this group. In serious chronic asthma, concern for bone structure should not prohibit the cautious use of appropriate corticosteroid regimens at the lowest possible maintenance dose.

Adrenal Cortex Hormones↗
PubMed1982

Effect of bacteriophage lambda infection on synthesis of groE protein and other Escherichia coli proteins.

We used two-dimensional gel electrophoresis to quantitate the changes in rates of synthesis that follow phage lambda infection for 21 Escherichia coli proteins, including groE and dnaK proteins. Although total protein synthesis and the rates of synthesis of most individual E. coli proteins decreased after infection, some proteins, including groE protein, dnaK protein, and stringent starvation protein, showed increases to rates substantially above their preinfection rates. Infection by lambda Q- affected host synthesis in the same way as infection by gamma+, whereas infection by lambda N- showed no detectable effect on host synthesis. Deletion of the early genes between att and N abolished the effect, and shorter deletions in this region gave intermediate effects. By this sort of deletion mapping, we show that a large part, though not all, of the effect of lambda infection on host protein synthesis can be ascribed to the early region that contains phage genes Ea10 and ral. We compared the changes in protein synthesis after infection with the changes that occur in uninfected cells upon heat shock or amino acid starvation. The spectrum of changes that occurred on infection was very different from that seen after heat shock but quite similar to that seen during amino acid starvation. Despite this similarity of the effects of lambda infection and starvation, we did not detect any increase in the level of guanosine tetraphosphate during infection. We show that the groE protein is the same protein as B56.5 of Lemaux et al. (Cell 13:427-434, 1978) and A protein of Subramanian et al. (Eur. J. Biochem. 67:591-601, 1976).

Amino Acids↗
PubMed1982

Evaluation of the urethra in males with spinal cord injury.

Of 358 antegrade voiding urethrograms obtained in 200 males with spinal cord injury, the urethra was satisfactorily shown by 154 (77%), permitting evaluation of alterations related to cord damage, surgery, or iatrogenic trauma. In 105 cases the neurogenic urethra was normal, demonstrated only minor distension, or had a patulous appearance, in contrast to urinary tract changes such as a markedly neurogenic bladder, vesicoureteral reflux, and bladder calculi. In 49 patients, abnormalities included (a) changes related to surgical alleviation of sphincter dyssynergia; (b) iatrogenic changes such as diverticula strictures, undermining of the external sphincter ("spiral sign"), and intravasation of contrast material; and (c) pressure necrosis of the urethra. Some changes need no special treatment; others, such as pressure necrosis, require early recognition and prompt therapy.

Adolescent↗