Biomedical subjects
Publications and source records attributed to R M Thomas.
Plexiform tumorlet is a rare lesion usually found in the myometrium and is believed to be a variant of epithelioid leiomyoma. Multiple plexiform tumorlets may have an infiltrative pattern and mimic endometrial stromal sarcoma. Only five cases of multiple plexiform tumorlets of the uterus have been reported, to the best of our knowledge. We now present the sixth case.
We report the clinical, pathologic, and immunophenotypic findings of inflammatory pseudotumors of the spleen in eight patients. The primary importance of recognizing these uncommonly found lesions is to distinguish them from malignant lymphoma, which splenic inflammatory pseudotumors may mimic clinically and radiologically. Grossly, the splenic inflammatory pseudotumors in this study ranged from 0.5 to 11.5 cm. One case was multinodular, and seven lesions were solitary. In general, the size of the lesion correlated with the presence of symptoms. The smaller lesions were usually incidental findings, discovered as part of the workup of idiopathic thrombocytopenic purpura (three cases), during staging for Hodgkin's disease (one case), or at autopsy (one case). Microscopically, the lesions were composed of a variable mixture of inflammatory cells admixed within a spindle cell proliferation. Small, cytologically normal lymphocytes and plasma cells were constant features, in a variable mixture, with neutrophilic and eosinophilic leukocytes present in some cases. Coagulative necrosis was located centrally in six lesions; neutrophilic leukocytes were correlated with the presence of necrosis. The presence of necrosis did not correlate with the presence of symptoms. Immunohistochemical studies revealed that the small lymphocytes present were predominantly T cells. Histiocytes and polytypic plasma cells were also numerous, whereas B cells were infrequent. Inflammatory pseudotumors of the spleen are benign lesions. The clinical follow-up for the seven patients in this study who underwent splenectomy showed no evidence of recurrence or subsequent development of a hematopoietic neoplasm, with a median follow-up of 18 months (range, 3 to 135 months).
A new serine proteinase inhibitor, mustard trypsin inhibitor 2 (MTI-2), has been isolated from white mustard (Sinapis alba L.) seed by affinity chromatography and reverse phase HPLC. The protein inhibits the catalytic activity of bovine beta-trypsin and bovine alpha-chymotrypsin, with dissociation constants (Kd) of 1.6 x 10(-10) M and 5.0 x 10(-7) M, respectively, at pH 8.0 and 21 degrees C, the stoichiometry of both proteinase-inhibitor complexes being 1:1. The amino acid sequence of MTI-2, which was determined following S-pyridylethylation, is comprised of 63 residues, corresponding to a molecular weight of about 7 kDa, and shows only extremely limited homology to other serine proteinase inhibitors.
The spectroscopic properties of syringomycin E, an antibiotic lipodepsinonapeptide associated with pathological states in plants, have been investigated by uv absorbance and CD spectroscopies, and by the synthesis of relevant model compounds. Initial studies [E. Vaillo, A. Ballio, P. L. Luisi, and R. M. Thomas (1990) in Peptides 1990, Giralt, E. & Andreu, D., Eds., Escom Scientific, Leiden, Netherlands] suggested that a significant contribution to the spectra was due to the presence of a zdehydroaminobutyric acid residue in the amino acid sequence. The model peptides N-Boc-L-Phe-delta zAbu-OMe and its analogue, N-Boc-L-Phe-L-Thr-OMe, lacking the unsaturated bond, were synthesized using standard solution chemistry, and a detailed investigation was made in which the spectra of the models and that of syringotoxin (an antibiotic closely related to syringomycin E but without a Phe residue) were compared with those of syringomycin E under a variety of solvent conditions. The uv absorbance spectra of both N-Boc-L-Phe-delta zAbu-OMe and syringomycin E clearly showed the presence of the unsaturated residue while the CD spectra were complex, environmentally sensitive, and contained contributions from both the delta zAbu and Phe residues. In the course of these studies extinction coefficients were obtained for syringomycin E and its dipeptide model. The origins of the uv and CD spectra are discussed in detail, and a comparison is made with the spectra of other, similar lipopeptide antibiotics. Finally, a structural model for syringomycin is proposed in which the changes induced in the spectrum by alterations in the solvent environment are accommodated.
We report time-of-flight mass spectra of test mixtures of six single-stranded DNA segments. The segments range in size from 8 to 60 nucleotides (molecular weight range 2413 to 18,602 Da). The best mass spectra were obtained by pulsed laser ablation of thin frozen films of an aqueous solution of the mixture from an oxidized copper substrate. These mass spectra are dominated by the molecular-ion peak for each DNA segment, and show little evidence of fragmentation, peak broadening or cluster formation. In contrast, mass spectra obtained using UV laser ablation from an anthranilic acid matrix yield broad peaks with evidence of fragmentation, and DNA segments longer than 26 nucleotides are difficult to detect.
Liver cell dysplasia is characterized by hepatocellular foci with nuclear atypia. It is often seen in cirrhosis and may be a precursor of hepatocellular carcinoma (HCC). To determine whether liver cell dysplasia is DNA aneuploid, 72 sections of 33 cirrhotic livers from the autopsy files of The Johns Hopkins Hospital were studied, and 14 foci of dysplasia from 13 cirrhotic livers were selected. Patients ranged in age from 32 to 70 years. Histologically, there were 10 foci of low-grade dysplasia and four foci of high-grade dysplasia. Nine HCCs served as positive controls; seven autopsy livers with no morphologic or clinical evidence of primary liver disease served as negative controls. One focus of HCC and one focus of dysplasia were unsatisfactory for analysis. Flow cytometric examination demonstrated subpopulations with DNA abnormality in four of nine (44%) foci of low-grade dysplasia, of which three were aneuploid. Three of four (75%) foci of high-grade dysplasia were aneuploid. Six of eight (75%) HCCs showed DNA abnormality, of which five were aneuploid. DNA aneuploidy was not present in the seven control livers; however, one showed DNA abnormality. We conclude that liver cell dysplasia is a morphologic entity that contains DNA aneuploid cells, a feature that supports the role of liver cell dysplasia in the evolution of HCC.
BACKGROUND: Sequential visual field testing is an extremely helpful adjunct to ophthalmoscopy and fundus photography in the management of cytomegalovirus (CMV) retinitis with the antiviral agents ganciclovir or foscarnet in patients with the acquired immune deficiency syndrome (AIDS). The authors studied the visual field defects found in a series of 110 patients with AIDS and CMV retinitis. METHODS: Ophthalmoscopy and fundus photography were performed on all patients. Visual field analysis was performed with either tangent screen, Goldmann kinetic, or Humphrey automated static perimetry. RESULTS: Of 166 eyes in 110 patients with CMV retinitis, visual field defects were present initially in 92 (55%) eyes of 78 (70%) patients, and ultimately in 97 (53%) eyes of 90 patients in whom follow-up was available. Stabilization of visual field defects was indicative of controlled retinitis. CONCLUSION: Sequential visual field testing will confirm ophthalmoscopic evidence of successful antiviral treatment of CMV retinitis and will corroborate very early progression of previously controlled retinitis.
Gastrin releasing peptide (GRP) is the mammalian equivalent of bombesin. Bombesin has been shown to stimulate canine ACTH and cortisol secretion in a dose-related manner. In the present study, following a 30-40 min saline infusion, a progressively-increasing, stepwise infusion of GRP (60, 600, 1200 pmol/kg per h) or pentagastrin (PG) (2, 4, 8 micrograms/kg per h) was administered. Each drug dose was infused for 40-45 min and blood samples were drawn at 20-22.5 min intervals. GRP caused significant, dose-dependent increases in plasma ACTH (145 +/- 6%, 242 +/- 49%, 270 +/- 78% of control) and cortisol (158 +/- 16%, 218 +/- 26%, 250 +/- 62% of control). The dose of GRP required for a half-maximal cortisol response was 120 pmol/kg per h, while that for ACTH was 140 pmol/kg per h. PG had no effect on either ACTH or cortisol. While PG is apparently not involved in GRP/bombesin release of ACTH or cortisol, similar mechanisms of action for GRP and bombesin are suggested by their equimolar potencies.
The neutrophil serine proteinases elastase and cathepsin G produce connective tissue injury, the extent of which depends on the balance between these enzymes and their inhibitors. The most important of these inhibitors is alpha 1-proteinase inhibitor, a member of a superfamily of homologous proteins known as serpins. Neutrophil cytosol inhibited the activities of human neutrophil elastase and cathepsin G in a dose-dependent fashion. To demonstrate formation of an enzyme-inhibitor complex, we combined 125I-elastase or 125I-cathepsin G with neutrophil cytosol or alpha 1-proteinase inhibitor and analyzed the products by polyacrylamide gel electrophoresis. Unbound elastase and cathepsin G each migrated to an apparent molecular weight of 25 kDa. In the presence of cytosol from neutrophils both radiolabeled enzymes migrated with a relative size of 68 kDa, whereas in the presence of alpha 1-proteinase inhibitor the relative size was 85 kDa. Enzyme-inhibitor complexes were stable in sodium dodecyl sulfate at 100 degrees C but were dissociated by hydrolysis in ammonium hydroxide (1.5 mol/L) at 37 degrees C. Formation of each complex was prevented by pretreatment of elastase or cathepsin G with diisopropylfluorophosphate, indicating that the inhibitor binds to the active site of the enzyme. Exposure of either alpha 1-proteinase inhibitor or neutrophil cytosol to the myeloperoxidase-H2O2-halide system prevented complex formation, suggesting the presence of an oxidizable amino acid at the binding site of the inhibitor. By electrophoretic analysis, the molecular weight of the cytosolic inhibitor was 43 kDa and neutrophils contained approximately 1 attomol of inhibitor per cell. The isoelectric points of the elastase and cathepsin G inhibitor were 5.5-5.9 and inhibitors of the two proteinases coeluted using size exclusion chromatography. These data demonstrate that human neutrophil cytosol contains a single serpinlike protein that inhibits elastase and cathepsin G. The inhibitor may be important in protecting the intracellular environment from proteolytic injury during degranulation.
Direct exposure of cells to vigorous ultrasonic cavitation results predominantly in mechanical cell lysis, but latent effects due to production of toxic sonochemicals can also be present. Phosphate buffered saline (PBS) was exposed to 1.61 MHz ultrasonic cavitation at 20 degrees C in a rotating tube exposure system to build up sonochemical products. Single strand DNA breaks (SSBs) were then induced by treating Chinese hamster ovary (CHO) cells with the cavitated PBS for 30 min on ice. The SSBs resided in viable cells, as evidenced by their ability to repair the breaks when warmed. This indirect effect could be explained by the action of cavitation-generated hydrogen peroxide that had built up (e.g., to 16 microM after 30 min exposure) in the PBS. Dissolution of argon gas in the PBS before exposure enhanced the SSB effect and the H2O2 production. Addition of catalase to the cavitated PBS before cell treatment eliminated the H2O2 and the SSB gamma effect. Tests with hydrogen peroxide showed that 16 microM H2O2 treatment for 30 on ice was as effective as 1 Gy dose of 60Co gamma rays in producing single strand breaks. The SSB effect of H2O2 and gamma rays was reduced by addition of the radical scavenger cysteamine to the cells before treatment, but cysteamine did not reduce the SSB effect of direct exposure to ultrasonic cavitation. These results help to clarify the potential for genetic effects from ultrasonic cavitation. These effects help to clarify the potential for genetic effects from ultrasonic cavitation.
The rotating chamber provides a useful system for enhancing cavitation bioeffects so that they may be more easily studied. A tube with acoustically transparent windows was rotated at 72 rpm perpendicular to its axis. The 1.61 MHz ultrasound beam was switched on and off in 42 ms bursts to expose the chamber while it was aligned with the beam. The hemolysis of 0.5% suspensions of canine erythrocytes was used as a measure of the efficacy of this rotating exposure system. Use of dialysis membrane, agar plugs, plastic sealing film or wax film for the windows produced no differences in the results for exposure intensities above an apparent threshold of 2-2.8 W/cm2, up to 16 W/cm2, at which essentially 100% lysis was observed. Changing the tube length from 1.4 cm to 4 cm, or partitioning it into three 0.5 cm segments had little influence on the results, but a short 0.5 cm chamber had reduced efficacy. Pressurizing the suspension filled chamber at 10 MPa to reduce the population of cavitation nuclei reduced the hemolysis. Separately pressurizing the suspension or the chamber produced indistinguishable, smaller reductions in hemolysis. The results lead to the hypothesis that the hemolysis occurs primarily in the bulk of the medium (rather than on surfaces). Bubbles recycled by rotation into the medium move toward the back of the chamber at estimated speeds of 10 m/s, generating hydrodynamic stresses sufficient to cause the observed hemolysis.
Ultrasonic cavitation induces a multiplicity of bioeffects in cell suspensions exposed in a 72 RPM rotating-tube exposure system. Single strand DNA breaks (SSBs) were found in cultured Chinese hamster ovary (CHO) cells exposed directly to 1.61 MHz ultrasound at a continuous 8 W/cm2 spatial peak temporal average (SPTA) intensity with cavitation for 10 min at 2 degrees C. Viability assessed by the trypan blue test was less than 1%, which indicates that these SSBs were in dead cells. Burst mode exposure with 10.5 microseconds bursts repeated each 21 microseconds not only caused SSBs at 5.6 W/cm2 and 8 W/cm2 (SPTA) for 10 min, but also allowed 20% and 7% viability, respectively. In order to determine if any of these breaks resided in the viable fraction of cells, the exposures were repeated with a 30 min postexposure incubation period at 37 degrees C to allow breaks in viable cells to repair. No significant repair occurred, relative to the samples which remained at 2 degrees C to prevent repair. A similar result was obtained with 10.5 microseconds bursts repeated each 42 microseconds at 4 W/cm2 (SPTA) with 46% viability. Thus, the observed ultrasonically induced SSBs reside primarily in the nonviable fraction of cells.
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An improved high yielding procedure for the purification of myrosinase from Sinapis alba L. consisting of concanavalin A affinity chromatography followed by a chromatofocusing step is presented. The purified enzyme was homogeneous as judged by sodium dodecyl sulfate-gel electrophoresis and by analytical ultracentrifugation although the presence of at least three isoenzymes, with pI values from 5.05 to 5.15, was detected by isoelectric focusing. It was found that the enzyme has a molecular weight of 135.1 kg mol-1 and consists of two, possibly identical, subunits of molecular weight 71.7 kg mol-1. The structure of myrosinase was studied by circular dichroism. Contin analysis of the CD data indicates a mixed alpha-helix and beta-sheet conformation for the native protein a with approximately 19% alpha-helix and approximately 35% beta-sheet content. Denaturation with guanidinium chloride was found to be irreversible although the enzyme has excellent storage characteristics in aqueous solution.
Chemistry, molecular biology and biology have turned into visive sciences in which ideas and information are communicated by artistic impressions and cartoons. These sciences have, in fact, become dominated by what we term the Pictographic molecular paradigm under which reality is acritically approximated by drawings of some kind. But it goes further than this and has both social and philosophical implications of which, we feel, there is insufficient general awareness. Important questions should be asked in connection with this way of doing science, including, for example, as to whether drawings of chemical formulae and graphical representation in biology meet the criterion of objectivity. This paper discusses some of the implications of the pictographic molecular paradigm and its limits and dangers.
During 1988 self-report data were elicited from a study of 102 male and 103 female sex workers (prostitutes) in Edinburgh. Respondents were contacted by 'snowballing', mostly in licensed premises. This was reflected by high levels of self-reported alcohol and illicit drug use. Respondents reported that both alcohol and illicit drug use were commonplace in relation to their work and that many of their clients were under alcohol or drug effect at the time of contact. Condom use was unrelated to sex workers' alcohol or drug use, but was significantly associated with sex workers' assessments of the proportions of their clients also under the influence of illicit drugs.
During 1988 and 1989 self-reported data were obtained from 206 males and three females who had paid for physical sexual services. Respondents were contacted by "snowballing", mainly with the assistance of sex workers. The study group reported that both alcohol and illicit drug use were commonplace during their contact with prostitutes. No general association between alcohol and drug use and 'risky sex' was evident. Even so amongst males who had anal sex with males alcohol consumption was inversely related to condom use.
Hemolysis induced by 1.9-MHz ultrasound in 0.5% suspensions of canine erythrocytes with 3.7-microns-diam micropore-trapped gas bodies was investigated for a variety of biophysical conditions. For isotonic media, hemolysis increased with exposure duration (4-64 min) but did not greatly change with exposure temperature (15, 25, 37, and 48 degrees C), or prior heat treatment (48 or 50 degrees C for 30 min). The temperature results were especially interesting because increased temperatures might have been expected to increase the sensitivity of the cells to the ultrasonically activated gas bodies. Variations in osmolarity (180, 290, or 580 mOsm) had little influence on the results. Increasing the viscosity (0.7, 2.2, 2.3, or 4.2 cP) of the medium decreased the effect, and this did not seem to depend on the molecular weight of the dextran additive (9400 or 250,000). A medium with elevated mass density (1.12 g/cm3) seemed to increase the effectiveness of the exposures. This condition eliminated the density difference between the cells and the medium, and might have been expected to reduce the effectiveness of the exposures, because the radiation force, which theoretically gathers cells to the gas bodies, is minimized for such conditions. This information should aid in developing refinements to the theoretical understanding of low-intensity ultrasonic bioeffects.