PubMed Health⌕ Search

Biomedical subjects

R A Robinson

Publications and source records attributed to R A Robinson.

At least 19 recordsLinked to original sources
PubMed1992

Factor Xa interacts with two sites on monocytes with different functional activities.

Studies were performed to elucidate the functional significance of factor Xa interactions at the monocyte membrane in the presence and absence of factor Va, with respect to prothrombin and factor IX cleavage. Factor Xa-catalyzed prothrombin activation at the monocyte surface was absolutely dependent on the addition of factor Va, indicating that thrombin was generated solely by a membrane-bound complex of factors Va and Xa. In contrast, in the absence of added factor Va, factor Xa bound to monocytes catalyzed the cleavage of factor IX to the nonenzymatic intermediate factor IX alpha through a reaction that was dependent on both monocyte and factor Xa concentration. At limiting factor Xa concentration, added factor Va inhibited the factor Xa-catalyzed cleavage of factor IX, suggesting that a monocyte-bound complex of factors Va and Xa did not recognize factor IX as a substrate. These combined data suggest that factor Xa interacts with the monocyte through two sites which can be distinguished by their requirement for added factor Va and their expression of different functional activities. Both functional sites could be distinguished also by their differential susceptibility to inhibition by a monoclonal antibody directed against the light chain of factor Va (alpha-HFV1). At the monocyte surface, the factor Va/Xa-catalyzed activation of prothrombin was maximally inhibited with 0.25 mumol/L alpha-HFV1, whereas 1.0 mumol/L alpha-HFV1 was required to effect 50% inhibition of the factor Xa-catalyzed cleavage of factor IX. The ability of factor Va to modulate factor Xa substrate specificity was investigated further. Factor Xa bound to thrombin-activated platelets either through platelet-released factor Va or added factor Va did not cleave factor IX. Consistent with this result, a plasma concentration of factor IX had no effect on thrombin generation catalyzed by a platelet-bound complex of factors Va and Xa. In marked contrast, factor Xa bound to phospholipid vesicles either independently or in complex with factor Va catalyzed factor IX cleavage with equal efficiency. These combined data indicate that factor Va bound to cell surfaces modulates factor Xa substrate specificity, whereas no discriminatory effect is conferred by factor Va bound to phospholipid vesicles. Thus, by providing two distinct sites at its membrane surface, the monocyte modulates factor Xa binding and the functional activity expressed by the bound enzyme, depending on the availability of factor Va.

Antibodies, Monoclonal↗
PubMed1992

Endotoxin enhances the expression of monocyte prothrombinase activity.

Thrombin is generated on the surface of mononuclear cells (MNCs) through the assembly and function of the prothrombinase complex consisting of the enzyme factor Xa, the cofactor/factor Va, calcium ions, and an appropriate membrane surface for proper assembly of the protein constituents. Assays performed in the presence of factors Va and Xa indicated that endotoxin significantly enhanced the prothrombinase activity (1.5- to 2.5-fold; P less than .001) expressed by MNCs in a dose- and time-dependent manner. Monocytes present in the MNC suspensions were responsible for this increased activity through processes resulting in both enhanced cellular activity and the enhanced release of membranous vesicles. Endotoxin was without effect on the expression of lymphocyte prothrombinase activity. Scanning electron microscopy techniques indicated that endotoxin resulted in extensive membrane blebbing of the monocytes present in the MNC suspensions with no effect on the morphology of the lymphocytes. Within 5 hours, endotoxin maximally enhanced the prothrombinase activity expressed by the monocyte membrane surface 2.8-fold, whereas 8 hours was required to maximally enhance the activity associated with the released vesicles by twofold. The observed increase in activity expressed by the monocyte membrane surface was due solely to endotoxin, since the activity expressed by the unstimulated monocyte membrane surface remained unaltered over time. In contrast, cell vesiculation, which occurred in the absence of any stimulus, was further enhanced by endotoxin. The increase in activity associated with the released vesicles from both stimulated and unstimulated cells paralleled an increase in the vesicle number as determined by flow cytometric analyses. The vesicle released from both unstimulated and stimulated monocytes were indistinguishable in size as determined by image analysis and ranged between 0.05 and 0.3 microns in diameter. 2-Deoxy-D-glucose (2DG) significantly enhanced the prothrombinase activity expressed by the monocyte membrane surface, as well as the released vesicle fraction, when used alone or in addition to endotoxin. The enhanced activity associated with the vesicle fraction again was attributed to the release of more vesicles. In contrast, cycloheximide decreased the prothrombinase activity expressed by the monocyte membrane surface, as well as the activity associated with vesicles released from both stimulated and unstimulated cells. These data suggest that the expression of monocyte prothrombinase activity can be significantly enhanced by endotoxin through processes that alter the monocyte membrane surface and augment the vesiculation process. Both processes appear to be regulated by protein synthesis and adenosine triphosphate (ATP)-dependent mechanisms.

Blood Proteins↗
PubMed1992

Extraskeletal myxoid chondrosarcoma of the pleura. Report of a case clinically simulating mesothelioma.

A primary extraskeletal myxoid chondrosarcoma of the pleura that clinically mimicked a malignant mesothelioma in a 66-year-old man with a history of asbestos exposure is described. Although exceedingly rare in this location, the characteristic histologic features, immunohistochemical reactivities, and ultrastructural features support the diagnosis of extraskeletal myxoid chondrosarcoma. Many ferruginous (asbestos) bodies consistent with the exposure history were found in the lung tissue sections and confirmed by energy-dispersive spectrometry. This case demonstrates an unusual pleural primary neoplasm associated with asbestos.

Aged↗
PubMed1992

Results of radical perineal prostatectomy with adjuvant brachytherapy.

Retrospective analysis of outcome in 137 patients who underwent radical perineal prostatectomy and bilateral injection of gold-198 implants into the periprostatic tissues and/or neurovascular pedicles as treatment for prostatic adenocarcinoma was performed. Patients had undergone treatment between 1975 and 1985. Local recurrence developed in 22 patients (16.1%) and distant metastases developed in 33 (24.1%). Clinical and surgical staging of disease and Gleason grading of pathologic specimens were performed retrospectively. Kaplan-Meier local recurrence, freedom from relapse (FFR), and survival rates decreased with increasing stage and pathologic grade. With clinical staging, these rates were not statistically different from previous rates achieved with external beam radiation therapy, and with pathologic staging, they were not statistically different from previous rates achieved with prostatectomy. The authors conclude that (a) 5-year follow-up is inadequate to determine local control rates after prostatectomy; (b) use of implants did not improve local control, FFR, or survival rates of 10 years; and (c) method of staging probably has more effect on local control, FFR, and survival rates than does treatment modality.

Adenocarcinoma↗
PubMed1992

Mechanisms of p185HER2 expression in human non-small cell lung cancer cell lines.

To identify mechanisms that allow p185HER2 expression in lung cancer, we performed Western, Southern, and Northern blot analyses of 14 cell lines derived from human non-small cell lung carcinomas and one cell line derived from a human mesothelioma. Human bronchiole epithelial cells and rat type II pneumocytes were found to express p185HER2 at low to undetectable levels by Western blot technique. In contrast, 13 lung cancer cell lines expressed p185HER2, and eight of these 13 expressed p185HER2 at levels at least 2-fold higher than that found in normal bronchiole epithelial cells or type II pneumocytes. Genomic Southern analysis showed that amplification of the HER2 gene was present in only one of the eight cell lines that expressed p185HER2 at these higher levels. Increased levels of steady-state HER2 mRNA occurred in the remaining seven cell lines. We conclude that in human non-small cell lung carcinoma cell lines the most common mechanism resulting in increased p185HER2 expression is due to mechanisms that increase HER2 mRNA levels, with HER2 gene amplification occurring less commonly.

Adenocarcinoma↗
PubMed1992

Multiplex polymerase chain reaction.

The polymerase chain reaction (PCR) is a widely utilized assay for specifically amplifying small fragments of DNA. Multiplex PCR is the amplification of more than one DNA fragment per reaction and has many potential uses. When more than one primer set per reaction tube is utilized, the total number of tubes in any one experiment may be reduced, conserving expensive reagents and decreasing possible contamination. Multiplex PCR allows for an assay of the gene of interest and assures that the amplification process proceeds as expected with the use of a companion control genome primer set. Multiplex PCR is useful in assaying DNA extracted from samples of immunocompromised patients in which more than one infectious agent may be suspected such as simultaneous EBV and CMV detection. Multiplex PCR offers many advantages over single reaction PCR and has been found to be an useful adjunct in our laboratory.

Base Sequence↗
PubMed1992

Genomic alterations in sarcomas: a histologic correlative study with use of oncogene panels.

Amplification and rearrangement of cellular proto-oncogenes are two of the several possible genetic alterations implicated in carcinogenesis and tumor progression. Although morphologically similar tumors may be heterogeneous at the level of the genome, some tumor types have shown relatively frequent and consistent abnormalities of specific oncogenes. In order to determine the frequency of oncogene amplification and rearrangement in several types of human sarcomas and to determine if histologically similar tumors have common genetic alterations, we analyzed 26 primary sarcomas by Southern hybridization. The oncogene probes utilized were N- and H-ras, sis, EGF-R (erb-B-1), neu (erb-B-2), fos, N- and c-myc, mos, and yes. The tumors studied included: five rhabdomyosarcomas (one alveolar, four embryonal), six malignant fibrous histiocytomas, six leiomyosarcomas, four liposarcomas, two Ewing's sarcomas, one osteosarcoma, and two fibrosarcomas. Oncogene abnormalities were identified in three tumors. One rhabdomyosarcoma showed 12-fold amplification and concurrent rearrangement of sis. This particular tumor also revealed rearrangement of H-ras and 15-fold amplification of c-myc. A second rhabdomyosarcoma revealed rearrangement of neu. A liposarcoma had a sis rearrangement. These findings suggest that many sarcomas show no common structural oncogene abnormalities. The presence of differing oncogene alterations within the rhabdomyosarcoma group indicates genetic heterogeneity among histologically similar sarcomas. The finding of a sis rearrangement in both a liposarcoma and a rhabdomyosarcoma, however, may suggest common oncogenesis among different tumor types.

Adolescent↗
PubMed1992

DNA extraction by sonication: a comparison of fresh, frozen, and paraffin-embedded tissues extracted for use in polymerase chain reaction assays.

DNA extraction from fixed tissues can be the most laborious and complex step in amplifying DNA by the polymerase chain reaction (PCR). We have previously reported a rapid and efficient method for extracting DNA by the use of sonication and glass beads. We have extended our experiences with this technique using fresh, frozen, and formalin-fixed paraffin-embedded tissues with and without the use of glass beads and report their results. Multiple tissue types were obtained at autopsy or as part of a surgical specimen. DNA was extracted from identical tissue when the sample was fresh, frozen, or formalin-fixed paraffin-embedded. Our results indicate that in most instances the sonication technique, which takes only 30 min from start to finish, can rapidly extract fresh, frozen, or formalin-fixed paraffin-embedded tissue and is superior to other rapid extraction techniques in terms of quality and quantity of DNA. It is much more rapid than those techniques that use long digestion periods. This technique will be of great value to those investigators extracting DNA for polymerase chain reaction assays.

DNA↗
PubMed1992

Thromboxane and prostacyclin production in ponies with colonic volvulus.

Effects of 1 hour of colonic volvulus and 3 hours of reperfusion on concentrations of thromboxane (TXB2) and prostacyclin (6-keto-PGF1 alpha) in portal, pulmonary arterial, and jugular blood were determined by radioimmunoassay to assess the site of production and clearance of these eicosanoids from the circulation in 5 anesthetized ponies. Colonic volvulus had no significant effect on mean arterial pressure or TXB2 concentrations, but significantly (P less than 0.05) increased 6-keto-PGF1 alpha concentrations in all blood samples. Immediately after colonic reperfusion, all eicosanoid concentrations were significantly (P less than 0.05) increased. Then, TXB2 returned to baseline values, whereas 6-keto-PGF1 alpha concentrations remained significantly (P less than 0.05) high for the remainder of the study. Eicosanoid concentrations were significantly (P less than 0.05) greater in portal blood than in pulmonary arterial and jugular blood samples at all periods. This suggests that the splanchnic circulation is the primary site of eicosanoid production during and after colonic volvulus and the liver appears to provide most of the circulatory clearance of thromboxane and prostacyclin.

Animals↗
PubMed1991

Identification of self peptides bound to purified HLA-B27.

A pool of endogenous peptides bound to the human class I MHC molecule, HLA-B27, has been isolated. Microsequence analysis of the pool and of 11 HPLC-purified peptides provides information on the binding specificity of the HLA-B27 molecule. The peptides all seem to be nonamers, seven of which match to protein sequences in a database search. These self peptides derive from abundant cytosolic or nuclear proteins, such as histone, ribosomal proteins, and members of the 90K heat-shock protein family.

Amino Acid Sequence↗
PubMed1991

Morphometric studies in intraductal breast carcinoma using computerized image analysis.

A morphometric study was performed using computerized image analysis on the histologic specimens of 26 patients with intraductal carcinoma of the breast and 26 normal control patients. A significant incidence of necrosis (56%) was observed in the breast ducts containing intraductal carcinoma. This was characterized by one or more areas of necrosis surrounded by a rim of viable tumor cells. The mean diameter of the ducts containing intraductal carcinoma was 349 microns compared with a mean diameter of 90 microns for the normal ducts. The mean diameter of the ducts containing necrosis was 470 microns compared with a mean diameter of 192 microns for the ducts containing a solid pattern of intraductal carcinoma. Central necrosis occurred in 94% of the ducts more than 180 microns in radius, whereas only 34% of the ducts less than 180 microns in size contained necrosis. The width of the viable neoplastic tissue was less than 180 microns in 91% of the ducts. These results are analogous to the findings of Thomlinson and Gray in human lung tumor cords and provide indirect evidence for the existence of a hypoxic compartment in intraductal carcinoma of the breast. This could be an explanation for the higher local failure rate after conservative surgery and irradiation for infiltrating cancers containing an extensive intraductal component.

Adult↗
PubMed1991

Monitoring surface conditions of a Thoroughbred racetrack.

During a pilot study at a Thoroughbred racetrack, information was collected to include weather conditions and track surface properties (moisture content, composition, strength, and coefficient of friction between surface and hoof). Measured weather variables did not correlate to any pattern of horse injuries of breakdowns. Surface moisture content was variable, whereas the moisture content of the compacted cushion was constant. Track surfaces around the starting chutes were more compacted than were other areas of the track. Next to the rail, track surface was softer than the surface toward the middle of the track. The coefficient of friction between a hoof and the surface was not affected by location or surface moisture content.

Animals↗
PubMed1991

The effect of hyperbaric oxygen on growth of human squamous cell carcinoma xenografts.

Hyperbaric oxygen is an important adjunct to the treatment of patients with head and neck cancer with existing or recurrent wound healing problems. Anecdotal clinical observations and a recent study of chemically induced oral cancer in hamsters have raised concern that hyperbaric oxygen therapy may accelerate tumor growth in such patients. This study evaluated the effect of hyperbaric oxygen therapy on the growth of human squamous cell carcinoma xenografts in a proved animal model. Fresh tumor specimens from three patients with head and neck squamous cell carcinoma of varying degrees of differentiation were first subcutaneously transplanted into a nude mouse host. Growing xenografts were then transplanted into one of three mouse groups. Half of the mice in each group were given hyperbaric oxygen therapy. The transplant volume as an index of tumor growth was measured in controls and mice given hyperbaric oxygen therapy six times during the 3-week course. Xenograft growth was almost linear in all mice. No statistical difference in overall group mean growth rates was observed in mice given hyperbaric oxygen or control mice regardless of the degree of tumor differentiation. Xenograft tissue from all mice was microscopically examined for tumor mitotic indices and degree of differentiation. This study suggests that hyperbaric oxygen therapy has no effect on established tumor xenograft growth.

Animals↗
PubMed1991

Cytomegalovirus detection in bone marrow transplant patients with idiopathic pneumonitis. A clinicopathologic study of the clinical utility of the polymerase chain reaction on open lung biopsy specimen tissue.

The morbidity and mortality rates of cytomegalovirus (CMV) infections, including pneumonitis in bone marrow transplant patients, are well documented and yet no rapid, sensitive diagnostic tool is available. To test the polymerase chain reaction as such a diagnostic tool, formalin-fixed, paraffin-embedded open lung biopsy material was selected from post-bone marrow transplant patients in whom pulmonary parenchymal changes were evident but viral inclusions were not seen. As a control, other immunosuppressed (non-bone marrow transplant) patients and low-risk nonimmunosuppressed patients were studied in a similar manner. Viral culture results and clinical data were available on all the high-risk patients. Two of 15 high-risk patients were found to have amplifiable CMV DNA despite the lack of histologic viral inclusions. One of these patients had been treated recently for CMV pneumonia, and the other had a positive culture of the lung specimens for CMV 13 days after biopsy. None of 12 control patients had amplifiable CMV DNA. These data indicate that the polymerase chain reaction is more sensitive than histologic examination and at least as sensitive as viral culture without evidence of false-positive results.

Adult↗
PubMed1991

Magnetic resonance imaging of pediatric head and neck cystic hygromas.

We retrospectively reviewed the magnetic resonance imaging (MRI) findings of eight pathologically proved cystic hygromas in seven pediatric patients. All lesions showed multiple cysts, best depicted on T2-weighted images (T2WI). Six of the eight lesions had well-defined borders. Fluid-fluid levels were visualized in seven of eight lesions, with very high signal intensity of the upper fluid on T2WI. On T1-weighted images, all lesions showed a mean signal intensity greater than that of muscle (1.6 times) and cerebrospinal fluid (CSF; 4.04 times) and less than that of fat (0.5 times). On T2WI, the mean signal intensity was greater than that of CSF (1.8 times), muscle (9.45 times), and fat (2.54 times). Chemical analysis of the cystic fluid from one lesion showed high lipid content and hemorrhage, consistent with the preoperative and in vitro MRI findings on the fluid from the same patient. Lesion anatomic distribution showed frequent posterior triangle involvement; however, the epicenter of 75% of the lesions was outside the posterior triangle. Only one lesion had involvement limited to the posterior triangle. There was equal distribution of right and left sides and no midline lesion. Seven lesions displaced the sternocleidomastoid muscle laterally, whereas one displaced it posteriorly, with no evidence of muscle infiltration. Only those patients with submucosal involvement (two of seven) had respiratory symptoms. Gadolinium provided no additional information with regard to diagnosis or extent of involvement. Our experience indicates that MRI is useful in the diagnosis and treatment planning of cystic hygromas.

Child, Preschool↗
PubMed1991

Squamous cell carcinoma in an inverted papilloma of the buccal mucosa.

Inverted papillomas of the oral cavity are rare lesions. Although in the seven oral cases previously reported the lesions were benign, approximately 10% to 15% of inverted papillomas of the nasal cavity and paranasal sinuses develop or are associated with squamous cell carcinoma. This report presents a case of squamous cell carcinoma arising in an inverted papilloma of the buccal mucosa. Histologically, this lesion demonstrated the morphologic features of inverted papilloma in the superficial portion, and squamous carcinoma in deeper sections. This case suggests that although rare, inverted papillomas of the oral cavity should be considered potentially malignant or capable of harboring a malignancy.

Aged↗
PubMed1991

Oncogene abnormalities in astrocytomas: EGF-R gene alone appears to be more frequently amplified and rearranged compared with other protooncogenes.

Ten astrocytomas were tested for gene amplification or rearrangement utilizing distinct probes to nine different oncogenes by Southern hybridization. The probes spanned the four major protein-coding classes of oncogenes; growth factor proteins (csis); growth factor receptor/tyrosine kinase-related proteins [erbB1 (epidermal growth factor receptor, EGF-R), neu (HER2/neu, erbB2), mos, yes]; nuclear binding proteins (c-myc, c-fos); and guanosine 5'-triphosphate binding proteins (N-ras, H-ras). Three astrocytomas, all glioblastomas, showed amplification of EGF-R-related sequences, and two of these amplifications were rearranged. Both rearrangements appeared similar by two different restriction endonucleases. Our findings suggest that it is primarily the EGF-R protooncogene (erbB1) that is amplified or rearranged in astrocytic neoplasms. No other oncogenes were amplified or rearranged, although EGF-R and neu cross-hybridization produced a "pseudo-rearranged" pattern for neu in EGF-R-amplified cases. The similar EGF-R restriction endonuclease abnormalities seen in two patients warrant further study.

Adolescent↗