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Biomedical subjects

R W Hendrix

Publications and source records attributed to R W Hendrix.

At least 55 records · Page 3Linked to original sources
PubMed1992

Computed tomography of posterior fracture-dislocations of the shoulder: case reports.

Computed tomographic (CT) evaluation of seven posterior shoulder dislocations in five patients is reported. Computed tomography provided better visualization of the trough fracture in the humeral head than did conventional x-ray films or tomography. It also demonstrated fracture fragments not seen on conventional roentgenograms. The two cases of bilateral dislocation and one case of unilateral dislocation were caused by seizures. The two other cases of unilateral dislocation were caused by trauma.

Adult↗
PubMed1992

Anterior cruciate ligament injury: MR imaging diagnosis and patterns of injury.

The anterior cruciate ligament (ACL) is an important stabilizer of knee motion. Injury of the ACL can lead to substantial disability; an accurate diagnosis of ACL injury is vital in both short-term and long-term patient care. Magnetic resonance (MR) imaging has emerged as the study of choice to evaluate the status of the ACL and other associated structures in the knee. Sagittal MR images have been commonly used in the evaluation of the ACL. However, the authors believe that coronal and axial imaging planes can add useful information about ACL injury and, thus, lead to improved accuracy and confidence regarding diagnosis. Multiplanar imaging can readily demonstrate meniscal, ligamentous, and bone marrow injuries that commonly occur with the most frequent mechanisms of ACL injury. These mechanisms, in order of frequency, include internal rotation and valgus stress, hyperextension, and varus stress with external rotation. An understanding of these mechanisms is helpful in the MR diagnosis of ACL injury.

Anterior Cruciate Ligament Injuries↗
PubMed1991

Protein carpentry.

Explore the source record for details and available documents.

Journal Article↗
PubMed1991

Bacteriophage HK97 structure: wholesale covalent cross-linking between the major head shell subunits.

We describe initial genetic and structural characterizations of HK97, a temperate bacteriophage of Escherichia coli. We isolated 28 amber mutants, characterized them with respect to what phage-related structures they make, and mapped many of them to restriction fragments of genomic DNA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of HK97 virions revealed nine different protein species plus a substantial amount of material that failed to enter the gel, apparently because it is too large. Five proteins are tail components and are assigned functions as tail fiber subunit, tail length template, and major shaft subunit (two and possibly three species). The four remaining proteins and the material that did not enter the gel are head components. One of these proteins is assigned as the portal subunit, and the remaining three head proteins in the gel and the material that did not enter the gel are components of the head shell. All of the head shell protein species have apparent molecular masses well in excess of 100 kDa; they share amino acid sequence with each other and also with a 42-kDa protein that is found in infected lysates and as the major component of prohead structures that accumulate in infections by one of the amber mutants. We propose that all of the head shell species found in mature heads are covalently cross-linked oligomers derived from the 42-kDa precursor during head shell maturation.

Amino Acid Sequence↗
PubMed1991

Cortical bone metastases.

The bone scans and radiographs of 27 patients with solitary or multiple cortical bone metastases were retrospectively studied. Thirty-six cortical metastases were identified in 32 appendicular long bones. Origin of the tumors included lung, breast, kidney, pancreas, larynx, uterus, and site unknown. Cortical metastases have hitherto been reported as individual cases or in small numbers. The large number reported herein suggests that the occurrence of these lesions may be more common than previously expected. A cortical metastasis was the only evidence of metastatic disease in eight of the 27 patients.

Aged↗
PubMed1990

Case report 620. Progressive systemic sclerosis (PSS) with paraspinous and intraspinous calcifications.

Progressive systemic sclerosis (PSS) is a connective tissue disorder of unknown etiology and pathogenesis characterized by fibrosis of the skin (scleroderma) and variable involvement of several organ systems including the gastrointestinal tract, lungs, heart, and kidneys. Calcinosis cutis is a frequent finding, commonly seen in the soft tissues of the fingertips and over the knees and elbows. Calcifications may also occur in areas of muscle necrosis and have been reported in articular synovium. This report describes a patient with PSS in the form of subcutaneous calcifications and scleroderma who was noted to have extensive paraspinous and intraspinal calcific deposits, causing severe narrowing of the spinal canal. The radiographs of 66 patients with PSS seen at Northwestern Memorial Hospital of soft tissue calcifications.

Calcinosis↗
PubMed1990

Evaluating the multiply injured patient radiographically.

In the multiply injured patient there are obvious lesions that often overshadow other lesions, creating a significant possibility that they will be overlooked. Because of the high incidence of missed lesions in such patients, it is a good idea to approach the patient with the presumption that one may be overlooking something and ask oneself what other lesions may be associated with the known lesions. We have enumerated several injuries that frequently occur together and have called them clinical dyads. It is hoped that knowledge of the associations will prevent oversight of the second lesion. The radiographic examination serves as an extension of the physical examination, confirming clinical suspicions and documenting the extent of many injuries. We have outlined what we believe is a prudent radiographic examination in a multiply injured patient. It provides information about the areas most likely to have injuries but is not so extensive that it hinders patient care. It is a starting place or survey and may lead to other, more complicated radiographic studies should the findings warrant them.

Communication↗
PubMed1989

Diagnostic imaging of fracture complications.

Fracture complications as discussed in this article are those abnormalities occurring as a direct result of or in association with a fracture or dislocation. Complications with radiographic findings are stressed, although those without definite radiographic manifestations are mentioned for the sake of completeness.

Angiography↗
PubMed1989

A study of glenohumeral orientation in patients with anterior recurrent shoulder dislocations using computerized axial tomography.

Thirty-six patients with recurrent anterior shoulder dislocations and 11 normal patients who had no history of shoulder problems were evaluated by a G.E. 8800 fourth generation computerized axial tomographer to quantitate humeral head retrotorsion and glenoid tilt. The study objective was to determine if osseous orientation was a major etiologic factor in patients with recurrent anterior shoulder dislocations. The normal position of the humeral head as determined by CT scan is 30 degrees retroversion with respect to its distal articular axis. In dislocations this value changes to a more anteverted position of 24 degrees retroversion. Glenoid tilt could not be given a single value since it changes from retroversion superiorly toward more anteversion inferiorly. This change in glenoid tilt was greater in the dislocators with inferior sections measuring 2 degrees anteversion in the dislocators and 1 degree retroversion in the uninvolved shoulder and in the normal population. The change in humeral retroversion and glenoid tilt in the recurrent dislocators was statistically significant when compared with the uninvolved shoulder and to the normal population. Thus, the glenoid humeral orientation appears to be a significant predisposing factor to recurrent anterior shoulder dislocations.

Adult↗
PubMed1988

Homologous plant and bacterial proteins chaperone oligomeric protein assembly.

An abundant chloroplast protein is implicated in the assembly of the oligomeric enzyme ribulose bisphosphate carboxylase-oxygenase, which catalyses photosynthetic CO2-fixation in higher plants. The product of the Escherichia coli groEL gene is essential for cell viability and is required for the assembly of bacteriophage capsids. Sequencing of the groEL gene and the complementary cDNA encoding the chloroplast protein has revealed that these proteins are evolutionary homologues which we term 'chaperonins'. Chaperonins comprise a class of molecular chaperones that are found in chloroplasts, mitochondria and prokaryotes. Assisted post-translational assembly of oligomeric protein structures is emerging as a general cellular phenomenon.

Adenosine Triphosphatases↗
PubMed1988

Translation initiation controls the relative rates of expression of the bacteriophage lambda late genes.

The late operon of bacteriophage lambda contains the genes encoding the morphogenetic proteins of the phage. These genes are transcribed equally from the single late promoter. Although the functional half-lives of the mRNA for the various genes of this operon vary less than 2-fold, their relative rates of expression have been shown to vary by nearly 1000-fold. This variation could result from differing rates of translation initiation, from overlapping upstream translation, or from differential elongation rates due to the presence of codons for which the corresponding tRNAs are rare. To distinguish between these possibilities, we have cloned sequences surrounding the initiator codons of several of these genes and measured their ability to drive synthesis of hybrid lambda-beta-galactosidase proteins. The rates of expression of the hybrid genes thus produced correlate very well with the natural rates of expression of the corresponding phage genes, suggesting that the rate of initiation of translation controls the relative expression rates of these genes.

Bacteriophage lambda↗
PubMed1988

The diagnosis of osteomyelitis in patients with pressure sores.

A prospective blind trial was undertaken to assess the usefulness of commonly used tests to diagnose osteomyelitis underlying pressure sores. Sixty-one pressure sores were studied, with a histopathologic diagnosis from the ostectomy specimen being available in 52. White cell count, erythrocyte sedimentation rate, plain pelvic x-ray, technetium-99m bone scan, computerized tomography, and Jamshidi needle bone biopsy were studied. The most useful individual test was a needle bone biopsy, with a sensitivity of 73 percent and a specificity of 96 percent. Technetium-99m bone scans and computerized tomography are not indicated in the diagnosis of osteomyelitis associated with pressure sores. Plain pelvic x-ray, white cell count, and erythrocyte sedimentation rate, with a diagnosis of osteomyelitis if any test is positive, is the most sensitive (89 percent), specific (88 percent), noninvasive workup. Jamshidi needle biopsy may be useful where these tests are negative and a clinical suspicion of osteomyelitis remains. Extent of surgical debridement and antibiotic therapy can then be rationally decided on the basis of this information.

Biopsy, Needle↗
PubMed1988

The painful shoulder.

Pain in the shoulder arises from a wide variety of abnormalities. The most common cause of acute pain in the nontraumatized shoulder is calcific tendonitis or bursitis readily identified by plain film radiography. On the other hand, the evaluation of chronic pain usually requires some combination of arthrography, CT, ultrasonography, and MRI to identify the source of the patients' complaints with certainty. The shoulder is rarely the site of a monoarticular process and is infrequently the dominant site of abnormality in a generalized articular disease. Clues to generalized disease processes are sometimes evidenced by changes within the shoulder present on the chest film. The source of pain in the shoulder was often elusive and puzzling to both the clinician and radiologist prior to the development of techniques such as arthrography, CT, and MRI that allow the precise delineation of soft tissue abnormalities. The judicious use of these techniques has, in large measure, helped to solve the puzzle.

Humans↗
PubMed1987

Localization of a DNA-binding determinant in the bacteriophage P22 Erf protein.

Four amber fragments of the recombination-promoting P22 Erf protein were characterized. The intact Erf monomer contains 204 amino acids. The amber mutations produce fragments of 190, 149, 130 and 95 amino acid residues, all of which are inactive in vivo. The 190 residue fragment is more susceptible to proteolysis in cell extracts than is intact Erf. It breaks down to a stable remnant that is slightly larger than the 149 residue fragment. The 149 and 130 residue fragments are stable; electron microscopy of the purified fragments reveals that they have similar morphologies, retaining the ring-like oligomeric structure, but lacking the tooth-like protruding portions of intact Erf. Intact Erf and the 149 residue fragment have similar affinities for single-stranded DNA; the affinity of the 130 residue fragment is 40-fold lower in low salt at pH 6.0. The 95 residue fragment is unstable in vivo. These observations, combined with previous observations, are interpreted as suggesting that the boundary of the amino-terminal domain of the protein lies between residues 96 and 130, that certain residues between 131 and 149 form part of an interdomain DNA-binding segment of the protein, that the boundary of the carboxy-terminal domain lies to the C-terminal side of residue 149, and that the carboxy-terminal domain is not necessary for assembly of the ring oligomer, although it is essential for Erf activity in vivo.

Amino Acid Sequence↗
PubMed1987

Carpal predominance in rheumatoid arthritis.

Radiographic and clinical evaluation of the relative severity of wrist versus hand involvement in 101 patients with rheumatoid arthritis revealed more severe changes in the wrists in 60%, equal involvement in wrists and hands in 37%, and more severe changes in the hands in 3%. There were severe changes in the wrists but little or no bone or joint change in the metacarpophalangeal and proximal interphalangeal joints in 43 (21%) of the 202 extremities studied. Serial examinations showed that, in time, the hand changes tended to overtake those in the wrist. Appreciation of this progression of wrist and hand changes can help the physician avoid diagnostic difficulties in a significant percentage of patients.

Adult↗