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Biomedical subjects

R C Thompson

Publications and source records attributed to R C Thompson.

At least 307 records · Page 17Linked to original sources
PubMed1988

Neuropathic arthropathy as a possible cause of failure of a whole joint allograft. A case report.

This report illustrates the fate of a whole joint allograft in a 23-year-old male with chondrosarcoma of the right hip. An extraarticular resection of the right proximal femur and surrounding pelvis was performed. Reconstruction was carried out with a fresh-frozen cadaveric allograft of articulated proximal femur and acetabulum with the capsule intact. Excellent union at the junction of host bone with the allograft was demonstrated roentgenographically 12 months later. Nineteen months after the operation, as weight bearing proceeded, sudden onset of instability of the joint occurred without pain. Collapse of the allograft with partial dissolution of the femoral head and acetabulum were observed roentgenographically. Reconstruction was achieved with a prosthetic implant. The roentgenographic and pathologic features of the allograft are suggestive of neuropathic arthropathy; however, the possibility of allograft rejection cannot be excluded but seems unlikely.

Acetabulum↗
PubMed1988

Fractures associated with neuropathic arthropathy in adults who have juvenile-onset diabetes.

Eighteen patients, twenty-five to fifty-two years old, who had juvenile-onset diabetes, had neuropathic arthropathy and fractures at the ankle or tarsus, most of which were bilateral. After a minimum follow-up of one year, four patients could not walk and fourteen were dependent on orthoses. In nine patients, the lesions produced fixed skeletal deformities that caused severe malum perforans, which in three patients was so severe that a below-the-knee amputation had to be done. In patients who had bilateral lesions, when the extremity that was initially involved was prevented from bearing weight, involvement of the contralateral limb became evident after an average of 4.5 months, compared with an average of twelve months in the patients who were allowed weight-bearing on the extremity that was initially involved. Our current treatment protocol is non-weight-bearing immobilization of the involved extremity, and we recommend prophylactic immobilization of the contralateral extremity with a protective cast or orthosis. All of the patients who had this treatment regimen could walk; in contrast, of the eleven patients who were not so treated, four could not walk.

Adult↗
PubMed1987

A form of human basic fibroblast growth factor with an extended amino terminus.

The amino acid sequence of a human placental bFGF was determined by a combination of protein and cDNA sequencing. The placental bFGF consists of 157 amino acid residues with a calculated molecular weight of 17,464 and is highly homologous to bovine pituitary bFGF. The human protein contains an amino terminal extension when compared to the sequence established for bovine bFGF (Esch et al., 1985) and to the sequence of the predicted translation product based on human bFGF cDNA clones (Abraham et al., 1986).

Amino Acid Sequence↗
PubMed1987

Dedifferentiated chondrosarcoma of bone. An immunohistochemical and lectin-histochemical study.

Ten cases of dedifferentiated chondrosarcoma (DCS) were immunohistochemically and histochemically compared with 12 de novo malignant fibrous histiocytomas, 10 osteoblastic osteosarcomas, 9 conventional chondrosarcomas, and 4 fibrosarcomas (all of bone or soft tissues), in order to discern similarities and differences in the immunophenotypes of these neoplasms. All cases of DCS and malignant fibrous histiocytoma were reactive for alpha-1-antichymotrypsin, and several examples of both tumor types bound peanut agglutinin, and expressed positivity for alpha-1-antitrypsin and lysozyme. None of these four cellular markers was observed in de novo osteosarcoma and fibrosarcoma; in addition, conventional chondrosarcoma lacked all of them except for peanut agglutinin receptors. S100 protein reactivity and binding of wheat germ agglutinin were detectable in conventional chondrosarcomas and in rare cells of the anaplastic components of primary DCS, but not in malignant fibrous histiocytoma arising ab initio and the other sarcomas. These results suggest the evolution of a second neoplastic cellular clone in DCS, with primitive morphological and phenotypic characteristics.

Adult↗
PubMed1987

Adriamycin cardiotoxicity and proton nuclear magnetic resonance relaxation properties.

Present noninvasive techniques to detect Adriamycin (doxorubicin) cardiotoxicity rely on assessment of myocardial function rather than direct observation of change in tissue character. Proton nuclear magnetic resonance imaging may provide a unique means of characterizing the myocardium. The relaxation properties T1 and T2 are related to certain biophysical properties of tissue such as water, lipid, and macromolecular content and have considerable impact on the intensity observed in nuclear magnetic resonance images. In a model of chronic Adriamycin cardiotoxicity in rats, T1 values of excised hearts were elevated, relative to control, in rats with histologic evidence of chronic cardiotoxicity (651 msec vs 622 msec, p less than 0.05) and more so in rats with gross evidence of toxicity or heart failure (668 msec, p less than 0.005). No significant change in T2 was observed. This T1 prolongation increases as disease worsens, whereas water concentration did not change significantly. The results suggest that predictable prolongation in T1 occurs in association with cardiotoxicity. In conclusion, proton nuclear magnetic resonance imaging methods could provide a new means for assessing Adriamycin cardiotoxicity.

Animals↗
PubMed1987

Taenia hydatigena: isolation of mitochondrial DNA, molecular cloning, and physical mitochondrial genome mapping.

Mitochondrial DNA was isolated from Taenia hydatigena, T. crassiceps, and Echinococcus granulosus using a cetyltrimethylammonium bromide precipitation technique. The technique is simple, rapid, reproducible, and does not require extensive high speed ultracentrifugation. The advantage of using mitochondrial DNA from taeniid cestodes for comparative restriction analysis was demonstrated. Mitochondrial DNA of T. hydatigena was isolated as covalently closed circular molecules. These were linearized by single digestion with BamHI and the molecular weight was estimated from the linear form of 17.6 kb. The mitochondrial DNA of T. hydatigena is therefore similar in size and structure to that of many other animal species. The entire mitochondrial genome was cloned into pBR322 in Escherichia coli and a restriction map of the recombinant molecule was constructed. The potential of using the cloned mitochondrial genome as a probe in speciation studies as well as for providing functional information on the role of the cestode mitochondrion is discussed.

Animals↗
PubMed1987

Comparative studies on the axenic in vitro cultivation of Giardia of human and canine origin: evidence for intraspecific variation.

Comparative studies were carried out on the in vitro cultivation of Giardia duodenalis from dogs and humans. Cultures were initiated with trophozoites obtained by artificial excystation of cysts present in human or canine faecal specimens, or using trophozoites collected from the small intestine of dogs postmortem. 12 new human isolates of G. duodenalis were established in axenic culture from cysts present in faecal specimens, and successfully cryopreserved, an overall success rate for in vitro establishment of Giardia from cysts of approximately 44%. In contrast, not one of 24 canine isolates, whether of faecal or intestinal origin, became established in vitro. Since identical media and culture conditions were used for the cultivation of both human and canine isolates, the results may reflect strain differences. The zoonotic significance of such intraspecific variation is discussed.

Adult↗
PubMed1987

CTAB precipitation of cestode DNA.

DNA probes are proving extremely valuable in the characterization o f cestodes - as well as other parasites. In this article, Kok Wei Yap and Andrew Thompson discuss some of the problems of DNA isolation, stressing the need for a gentle and economical procedure such as CTAB precipitation.

Journal Article↗
PubMed1987

The rat corticotropin-releasing hormone gene.

In this paper we have described the isolation and characterization of the rat corticotropin releasing hormone gene. Nucleotide sequence comparisons with the human CRH gene have demonstrated several interesting regions of homology and suggest that the gene was highly conserved through evolution. Additionally we have demonstrated the tissue-specific expression of the rat CRH gene. The regional distribution of expression parallels previously documented immunocytochemical demonstrations and supports the hypothesis that CRH peptides have multiple roles in different tissues. In the peripheral tissues that express CRH mRNA it will be very interesting to document the specific cell type of synthesis by using combined immunocytochemical and in situ histochemical techniques. Additionally we have described initial studies using gene transfer techniques to examine the cAMP responsiveness of the rat CRH gene. We are presently constructing other fusion genes (CRHCAT plasmids) in order to more carefully localize the DNA sequence in the rat CRH gene which mediates this effect, and compare it to the previously reported cAMP-responsive "consensus sequence." Similarly, we also plan to utilize the CRHCAT constructs to examine regulation of the rat CRH gene by glucocorticoids and several other hormone-mediated regulatory pathways. Through these CAT fusion studies we hope to gain a better understanding of the role of certain conserved sequences in the 5' flanking DNA for transcriptional control of the rat (and human) CRH genes.

Animals↗
PubMed1987

Rat corticotropin-releasing hormone gene: sequence and tissue-specific expression.

The rat corticotropin releasing hormone (CRH) gene has been isolated and characterized by DNA sequence analysis. The gene exhibits a structural organization similar to that of the human CRH gene. The nucleotide sequence encoding the entire rat CRH precursor is located on the second exon, while exon I encodes the 5'-untranslated region of the mRNA. Analysis of the nucleotide sequence homology between the human and rat CRH genes reveals several highly conserved regions including the CRH peptide-encoding sequence and the 5'-flanking sequence. RNA blot analysis demonstrates that CRH mRNA can be observed in numerous regions of the rat brain as well as the spinal cord, adrenal gland, pituitary, and testis.

Amino Acid Sequence↗
PubMed1987

Management of tumors of the shoulder girdle.

The differential diagnosis of all painful shoulders includes tumors of a wide variety. Evaluation of a shoulder tumor has several areas in common with other musculoskeletal neoplasms, but the function of the rotator cuff is a key consideration in treatment goals. Thorough evaluation of patients with persistent pain requires not only routine radiography, but also radionuclide imaging, computed tomographic (CT) scanning, magnetic resonance imaging, and angiography. As with all tumors, the importance of the biopsy cannot be overemphasized. A poorly executed biopsy can make limb salvage impossible. Surgical treatment of shoulder tumors will depend on age, type of tumor, extent of tumor, and neoplasm aggressiveness. Though in some instances limb sparing is not possible, a variety of reconstructive options exists that will salvage the distal limb and obtain satisfactory surgical margins.

Bone Neoplasms↗
PubMed1986

Actions of the anticodon arm in translation on the phenotypes of RNA mutants.

In previous publications, we have shown that it is practical to study the translational activity of tRNAs by replacement and alteration of the anticodon arm sequence of the genus on a plasmid clone. Experiments in which the anticodon arm sequence is transplanted between tRNA genes suggest that the translational activity is determined by these sequences. We have therefore made every variant of the anticodon loop and the three base-pairs of the stem proximal to the loop, in order to resolve the relation between the structure of Su7Am tRNATrp, and its function. All derivatives conserved the normal secondary structure of the molecule, which was known to be essential for translational activity. The probability of translation of the amber codon by these suppressors is measured in this work. This translational activity in vivo is rationalized in terms of data on the copy numbers of the plasmid clones, the nucleotide modifications of the tRNAs, the steady-state level of the mature tRNA, and the aminoacylation of these molecules. Nucleotide modification levels vary among these tRNAs, giving information about the specificities of modification systems that make O-methylribose, pseudouridine, and modified A in the anticodon arm. However, for this series of tRNAs, none of these modifications has a strong effect on translational efficiency of the tRNAs. A few of the substitutions reduce aminoacylation of the tRNAs with glutamine, as determined by comparison of suppression in normal strains and related strains, which have 25-fold elevated levels of the glutaminyl-tRNA synthetase (GlnRS). The substitutions that have the largest effect on GlnRS action are, unexpectedly, purines for conserved pyrimidines on the 5' side of the anticodon loop. Data on the concentrations of tRNA in vivo suggest that the anticodon loop and helix contribute similarly to the determination of the steady-state level of the tRNAs. This level varies sevenfold, though all tRNAs are processed from a homologous precursor made from the same transcription unit. Effects on levels appear to be mediated by changes in anticodon arm structure. A robust equation that relates aminoacyl-tRNA levels to suppressor efficiency is developed in order to resolve effects on tRNA levels and on ribosomal steps: E = A/(K + A), where E is efficiency, A is aminoacyl-tRNA concentration, and K is the effective concentration, or cellular tRNA content required for an individual tRNA to have an efficiency of 0.50. The tRNAs vary in their intrinsic ability to function on the ribosome (represented by K), after other influences have been normalized.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acyl-tRNA Synthetases↗