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Biomedical subjects

R W Hendrix

Publications and source records attributed to R W Hendrix.

18 recordsLinked to original sources
PubMed1992

Bacteriophage lambda PaPa: not the mother of all lambda phages.

The common laboratory strain of bacteriophage lambda--lambda wild type or lambda PaPa--carries a frameshift mutation relative to Ur-lambda, the original isolate. The Ur-lambda virions have thin, jointed tail fibers that are absent from lambda wild type. Two novel proteins of Ur-lambda constitute the fibers: the product of stf, the gene that is disrupted in lambda wild type by the frameshift mutation, and the product of gene tfa, a protein that is implicated in facilitating tail fiber assembly. Relative to lambda wild type, Ur-lambda has expanded receptor specificity and adsorbs to Escherichia coli cells more rapidly.

Adsorption↗
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

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↗
PubMed1979

The radiologic significance of the left pulmonary ligament. Experience with 26 patients.

Pathologic processes confined to or by the left pulmonary ligament present a confusing radiographic appearance. Such processes may simulate pleural scarring, parenchymal scarring, or even left lower lobe collapse. Radiologic awareness of this structure is limited because in the normal state, it is not visualized on either posteroanterior or lateral chest x-ray films. The absence of secondary signs of left lower lobe collapse, together with a process which may extend above the level of the left hilum, is valuable in confirming that such a triangular density seen behind the left cardiac border is disease in or confined by the pulmonary ligament, rather than left lower lobe collapse.

Adult↗
PubMed1978

Role of the host in virus assembly: cloning of the Escherichia coli groE gene and identification of its protein product.

Correct assembly of the heads of bacteriophages lambda and T4 requires the function of the groE gene of the Escherichia coli host. We have isolated a transducing derivative of lambda, called lambda gt-Ec.groE, that carries a functional copy of the groE gene. Unlike wild-type lambda, this phage is able to form plaques on hosts with a mutant groE gene. We have isolated an amber mutation in the groE gene carried by the phage, and this has made it possible to identify the groE product as a protein of molecular weight 65,000. In the phage, the groE gene is under the control of an early phage promoter.

Bacterial Proteins↗
PubMed1978

Symmetry mismatch and DNA packaging in large bacteriophages.

A model is presented for the mechanism of packaging double-stranded DNA into phage heads. The model is based on, and rationalizes, the mismatch in symmetry between the heads and tails of large bacteriophages. DNA movement is postulated to be mediated by a rotating protein structure at the tail-proximal vertex of the head.

Bacteriophages↗
PubMed1977

Scintigraphic evaluation of lymphoma: a comparative study of 67Ga-citrate and 111In-Bleomycin.

Sequential whole-body scans with both 67Ga-citrate and 111In-bleomycin were performed for 14 patients undergoing staging for Hodgkin's disease or other lymphomas. A comparison or these scans gave a sensitivity in detecting the pathologically-proved tumor sites of 84% for 67Ga-citrate and only 56% for 111In-bleomycin. In 12 patients, the gallium scan demonstrated the lesions more clearly; in the others, the uptake of the two radionuclides was equal. In no case was a clinically diagnosed or histologically proved lesion identified by 111In-bleomycin that was not also demonstrated by 67Ga-citrate. 111In-bleomycin does not complement the 67Ga-citrate scan in the scintigraphic evaluation of lymphomas.

Adolescent↗
PubMed1976

Efficacy of emergency radionuclide perfusion lung studies.

Over a one-year period, 206 patients with suspected pulmonary embolism received gamma camera perfusion lung images on an emergency 24 hr. basis. Clinical diagnosis listed pulmonary embolism in 37 of 39 patients whose images showed a high probability of it, in 28 of 69 whose images were abnormal but rated uncertain probability, and 5 of 98 with normal images. Retrospective clinical evaluation indicated 89 of the emergency images to be considered important, 95 contributory, and 22 not helpful in clinical management. As a result of the images, 80 patients were placed on heparin therapy of 198 considered for it, and 22 of 29 patients referred for hospital admission were placed on an outpatient basis. Delay in obtaining lung images creates the possibility of diagnostic uncertainty in interpreting the image.

Adolescent↗
PubMed1975

The matrix of the optic vesicle-presumptive lens interface during induction of the lens in the chicken embryo.

The cell coats of the presumptive lens cells and the extracellular interface between the lens rudiment and optic vesicle were investigated in the chicken embryo throughout the period during which lens induction is presumed to take place. Histochemical methods showed that the cell coats contained both glycoproteins and glycosaminoglycans. Autoradiography after [3H]glucosamine injection indicated incorporation of the precursor with subsequent localization primarily at the cell surface. No obvious changes in the properties of the coat were noted with the progression of early lens morphogenesis. The extracellular matrix at the interface between ectoderm and optic vesicle also contained glycoprotein and glycosaminoglycan. There was a heavy concentration of [3H]glucosamine-containing macromolecules in the area. Electron microscopy revealed that the interface consisted of the basement membrane systems of lens and optic vesicle, fused with their external fibrillar layers. In contrast to the findings on cell coats the density of the interfacial matrix increases appreciably during the lens induction period. Evidence suggests that the cells of the two ocular epithelia are themselves the source of the matrix materials. It is proposed that the macromolecules excreted by the epithelial cells into the interface interact at different concentrations to form aggregates of various structure by a process of self-assembly. This may be reflected in the different ultrastructure of the layers of the interfacial matrix. Quantitative changes in the density of the matrix, leading to increased adhesion between lens rudiment and optic vesicle, may restrict the lateral spreading of the lens cells and so fix the basal area of the lens rudiment. This, together with continued cell replication, may produce the cell crowding, placode formation and invagination characteristic of lens morphogenesis.

Amylases↗