A reversed-phase high-performance liquid chromatographic method for the determination and identification of clarithromycin as the drug substance and in various dosage forms.
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Capsules↗
Biomedical subjects
D M Brown
Publications and source records attributed to D M Brown.
Inflammatory response to particles in the rat lung: secretion of acid and neutral proteinases by bronchoalveolar leucocytes.
Leucocyte proteinases are considered to be central to the tissue damage that is associated with chronic inflammatory lung disease. Both acid and neutral proteinases have the ability to degrade connective tissue molecules and both may therefore play a part in tissue proteolysis in inflamed lungs. In this study we have used a rat model of lung inflammation to investigate levels of acid and neutral proteinase activity in the bronchoalveolar region of control and inflamed lungs. We assessed the ability of proteinases, secreted by resident and inflammatory bronchoalveolar leucocytes, to damage the connective tissue molecule fibronectin. Inflammatory bronchoalveolar leucocytes had greater ability to mediate connective tissue damage than had resident alveolar macrophages and the tissue proteolysis was mediated, in the main, by proteinases active at neutral rather than at acid pH. The increased secretion of proteinase by inflammatory leucocytes was dependent on in vivo stimulation: exposing resident or inflammatory bronchoalveolar leucocytes in vitro to particulate or soluble stimuli had no effect in increasing their ability to degrade fibronectin or secrete the inflammogenic proteinase, plasminogen activator. Thus, neutrophils in the bronchoalveolar region of the rat lung have proteolytic activity which is mediated largely by neutral proteinases.
Animals↗
Degradation of growth hormone releasing factor analogs in neutral aqueous solution is related to deamidation of asparagine residues. Replacement of asparagine residues by serine stabilizes.
The incubation of a solution of the human growth hormone releasing factor analog, [Leu27] hGRF(1-32)NH2 at pH 7.4 and 37 degrees, resulted in extensive degradation of the sample. The major degradation products were identified as the peptides [beta-Asp8, Leu27] hGRF(1-32)NH2 and [alpha-Asp8, Leu27] hGRF(1-32)NH2, produced by deamidation of the Asn8 residue. When tested as growth hormone (GH) secretagogues in cultured bovine anterior pituitary cells, [beta-Asp8, Leu27] hGRF(1-32)NH2 was estimated to be 400-500 times less potent than the parent Asn8 peptide, while [alpha-Asp8, Leu27] hGRF(1-32)NH2 was calculated to be 25 times less potent than the parent Asn8 peptide. Three additional analogs of [Leu27] hGRF(1-32)NH2 containing either Ser or Asn at positions 8 and 28 were prepared and evaluated for their GH releasing activity and stability in aqueous phosphate buffer (pH 7.4, 37 degrees). Based on disappearance kinetics, [Leu27] hGRF(1-32)NH2 had a half-life of 202 h while the other analogs had the following half-lives: [Leu27, Asn28] hGRF(1-32)NH2 (150 h); [Ser8, Leu27, Asn28] hGRF(1-32)NH2 (746 h); and [Ser8, Leu27] hGRF(1-32)NH2 (1550 h). After 14 days, incubated samples of the Asn8 analogs lost GH releasing potency, while the Ser8 analogs retained full potency. The potential for loss of biological activity brought about by deamidation of other engineered peptides and proteins should be considered in their design.
Amides↗
Persistent biological reactivity of quartz in the lung: raised protease burden compared with a non-pathogenic mineral dust and microbial particles.
This study assessed the potential harmfulness of particles in the lung by measuring their ability to elicit and maintain an inflammatory response and to damage lung tissue. It compared the inflammogenicity of two nondurable, biological particulates (Corynebacterium parvum and zymosan) with a pathogenic mineral dust (quartz) and a nonpathogenic dust (titanium dioxide) by dosing rats via the intratracheal route and measuring the consequent alveolitis. The magnitude and duration of the inflammatory response were assessed by measuring the total number of leucocytes and the percentage of neutrophils obtained by bronchoalveolar lavage. Two key functional parameters of the lavaged leucocytes--ability to degrade fibronectin and production of plasminogen activator--were also measured. A marked inflammatory response had occurred by one day after instillation, characterised by increases in total leucocyte numbers and percentage of neutrophils in the bronchoalveolar lavages, with all four test materials. In all but the quartz exposed animals, the inflammation subsided rapidly thereafter, approaching control levels by 15 days after injection; in the quartz exposed animals the alveolitis persisted for up to 30 days. All of the inflammogens generated chemotaxins in rat serum in vitro and so, by analogy, might also be expected to generate chemotactic activity in alveolar lining fluid which could contribute to the generation of an inflammatory response. The cellular inflammatory response was accompanied by a concomitant increase in the proteolytic activity of the bronchoalveolar lavage leucocytes but production of plasminogen activator remained unchanged. In vitro exposure to the inflammogens had no effect on the proteolytic activity against fibronectin or on the plasminogen activator activity of bronchoalveolar leucocytes.
Animals↗
Injurious effects of wool and grain dusts on alveolar epithelial cells and macrophages in vitro.
Epidemiological studies of workers in wool textile mills have shown a direct relation between the concentration of wool dust in the air and respiratory symptoms. Injurious effects of wool dust on the bronchial epithelium could be important in causing inflammation and irritation. A pulmonary epithelial cell line in vitro was therefore used to study the toxic effects of wool dust. Cells of the A549 epithelial cell line were labelled with 51Cr and treated with whole wool dusts and extracts of wool, after which injury was assessed. Also, the effects of grain dust, which also causes a form of airway obstruction, were studied. The epithelial injury was assessed by measuring 51Cr release from cells as an indication of lysis, and by monitoring cells which had detached from the substratum. No significant injury to A549 cells was caused by culture with any of the dusts collected from the air but surface "ledge" dust caused significant lysis at some doses. Quartz, used as a toxic control dust, caused significant lysis at the highest concentration of 100 micrograms/well. To determine whether any injurious material was soluble the dusts were incubated in saline and extracts collected. No extracts caused significant injury to epithelial cells. A similar lack of toxicity was found when 51Cr labelled control alveolar macrophages were targets for injury. Significant release of radiolabel was evident when macrophages were exposed to quartz at concentrations of 10 and 20 micrograms/well, there being no significant injury with either wool or grain dusts. These data suggest that neither wool nor grain dust produce direct injury to epithelial cells, and further studies are necessary to explain inflammation leading to respiratory symptoms in wool and grain workers.
Animals↗
Effects of IGF-I and glucose on protein and proteoglycan synthesis by human fetal mesangial cells in culture.
Abnormalities in proteoglycan metabolism have been implicated in the pathogenesis of diabetic nephropathy. Whether hyperglycemia plays a direct role in these events is unknown. To evaluate the effects of high glucose concentrations and insulinlike growth factor I (IGF-I) on kidney proteoglycan and protein metabolism, we incubated quiescent, subconfluent human fetal mesangial cells for 24 h in serum-free media containing either physiological (5.6-mM) or elevated (25-mM) glucose concentrations with or without 1.3 x 10(-9) M IGF-I. In the presence of physiological glucose concentrations, IGF-I stimulated incorporation of [3H]leucine into protein and [35S]sulfate or [3H]glucosamine into proteoglycans. High glucose concentrations significantly amplified IGF-I-mediated stimulation of protein synthesis but totally abolished IGF-I-induced proteoglycan synthesis. The hydrodynamic size and proportions of heparan-35SO4 and chondroitin/dermatan-35SO4 proteoglycans in all experimental media were the same. However, high glucose concentrations decreased the iduronic acid content of dermatan-35SO4. In separate experiments, quiescent cells were cultured for 7 days in media supplemented with 2% fetal calf serum. IGF-I had no effect on mesangial cell proliferation, but as cells reached confluence, high glucose concentrations significantly inhibited cell proliferation. This inhibition was not mimicked by isosmolar concentrations of mannitol. After 7 days, uptake of radioactive precursors into proteoglycans and proteins over 24 h was similar under all culture conditions. However, IGF-I decreased the ratio of [35S]sulfate to [3H]glucosamine in proteoglycans and their glycosaminoglycan side chains. This difference persisted in disaccharides derived by chondroitin ABC lyase digestion of dermatan-35SO4.(ABSTRACT TRUNCATED AT 250 WORDS)
Cell Division↗
An overview of role of matrix components.
The glomerular filtration barrier consists of complex matrix constituents interposed between the glomerular endothelial and epithelial cells, which constitute the lining of the glomerular capillaries. The matrix components include collagen and noncollagenous molecules such as laminin and proteoglycans. This review describes herein the metabolic consequences of diabetes mellitus to which increased permeability of the filtration barrier may be attributed by altering matrix molecules.
Animals↗
Leukocyte-mediated epithelial injury in ozone-exposed rat lung.
Both epithelial injury and inflammation are characteristic findings in the centriacinar regions of the lungs of rats exposed to ozone. In humans such effects could lead to long-term lung damage and disease. In animals, neoplastic change in the lungs after exposure to ozone has been described previously. The possible relationships between inflammatory cell recruitment, epithelial injury, and hyperplasia, with special regard to the important role of repair processes in leading to increased incidence of tumors in some species, have been addressed in the present study. We have previously described that leukocytes from lungs inflamed by different agents can injure epithelial cells in vitro. We have suggested that this leukocyte-mediated epithelial injury could enhance epithelial turnover in ozone-exposed lungs and so enhance the likelihood of tumor development. We, therefore, set out to test the hypothesis that bronchoalveolar leukocytes from ozone-exposed lungs can injure epithelial cells in vitro. PVG rats were exposed to 0.2, 0.4, 0.6, and 0.8 parts per million2 (ppm) ozone for seven hours per day for up to four days. On the morning following the last exposure, bronchoalveolar lavage was used to sample the bronchoalveolar leukocytes and the following parameters were assessed: total number, differential leukocyte count, production of oxidants, ability to degrade fibronectin, and ability to injure epithelial cells. In addition to these parameters, which were measured at all concentrations and time points in limited experiments, we also assessed macrophage size in short-term culture and inflammation in histological sections of lungs. Total number of lavageable cells was not affected by ozone inhalation. However, the percentage of macrophages decreased with ozone treatment and the percentage of neutrophils increased on days 1 and 2 at 0.6 and 0.8 ppm ozone. There was no significant effect of ozone exposure on the ability of neutrophils to degrade fibronectin or injure epithelial cells. Production of superoxide anion in response to stimulation with phorbol myristate acetate was significantly decreased by exposure to 0.6 ppm ozone, as described in previous studies. Macrophages from the lungs of rats exposed to ozone were larger than control macrophages.
Animals↗
The structure and application of oligodeoxyribonucleotides containing modified, degenerate bases.
Oligodeoxynucleotides containing modified pyrimidine bases which can stably hydrogen-bond to adenine and guanine and also purine bases which pair with thymine and cytosine residues in duplexes have been synthesised, as have oligomers with both such analogues. Structures have been investigated by melting transitions, n.m.r. spectroscopy and crystallography and then interpreted in terms of tautomeric equilibria. Applications to hybridisation probes and primers will be discussed.
Base Sequence↗
The supply and distribution of dental manpower in the state of Arkansas: a report.
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Arkansas↗
Total factor productivity modeling in hospital foodservice operations.
Total factor productivity (TFP) modeling, a ratio of outputs to inputs, was elaborated with terminology, resources, and outputs familiar to foodservice managers and evaluated for four hospital foodservice operations. Outputs and inputs (counts or currency) were converted to constant dollars for a defined base period by using base period rates and price indexes. After development, validation and pilot testing of a computer-assisted prototype, monthly TFP ratios were calculated from historical data. When TFP ratios were analyzed by regression against each of nine variables (six work force policies, two "demand for services" variables, and capital investment), few significant relationships were found. Although multiple regression analysis of those variables did not produce useful predictive equations, a similar analysis of partial and total factor productivity ratios yielded predictive equations that included up to four partial factor productivity ratios. Even though the labor statistic of meals per labor hour correlated positively with TFP ratios, the comparison provided incomplete and sometimes contradictory information. Total factor productivity measurement can provide foodservice managers with a more comprehensive analytical technique than is possible with only partial measures of productivity.
Data Collection↗
Gynecomastia.
Gynecomastia is a serious cosmetic concern for many adolescent and adult males. In the majority of cases no pathologic cause for the problem can be found. The authors discuss the types of surgical treatment of gynecomastia.
Breast↗
Molecular and crystal structure of d(CGCGmo4CG): N4-methoxycytosine.guanine base-pairs in Z-DNA.
The base analogue N4-methoxycytosine (mo4C) is ambivalent in its hydrogen-bonding potential, since it forms stable base-pairs with both adenine and guanine in oligomer duplexes. To investigate the base-pair geometry, the structure of d(CGCGmo4CG) has been determined by single-crystal X-ray diffraction techniques. The d(CGCGmo4CG)2 crystallized in a left-handed double helical structure (Z-type). Refinement using 2559 reflections between 10 and 1.7 A converged with a final R = 0.181 (Rw = 0.130) including 68 solvent molecules. The orthorhombic crystals are in the space group P2(1)2(1)2(1), with cell dimensions a = 18.17 A, b = 30.36 A, c = 43.93 A. The mo4C.G base-pair is of the wobble type, with mo4C in the imino form, and the methoxy group in the syn configuration.
Base Composition↗
A new guanine-specific reaction for chemical DNA sequencing using m-chloroperoxybenzoic acid.
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Base Sequence↗
Prostaglandin E2 promotes IL-4-induced IgE and IgG1 synthesis.
PG of the E series are generally known to suppress immune responses, however, we have found that PGE synergizes with IL-4 to induce IgE and IgG1 production in LPS-stimulated murine B lymphocytes. PGE2 and PGE1 (10(-6) to 10(-8) M) significantly increase IgE and IgG1 production (up to 26-fold) at all concentrations of IL-4 tested. In addition to its effects on IgE and IgG1, PGE also causes a significant decrease in IgM and IgG3 synthesis, suggesting that PGE may promote IL-4-induced class switching. The specificity of the E series PG effect is demonstrated by the fact that PGF2 alpha (10(-6) M) does not alter production of any of these isotypes. Because PGE can mediate its effects through cAMP in some cases, we investigated the importance of cAMP levels in regulation of isotype expression. Other agents that increase intracellular cAMP levels (cholera toxin and dibutyryl cAMP) were assessed for their ability to regulate isotype differentiation. Cholera toxin (100 pg/ml) and dibutyryl cAMP (100 microM) significantly enhanced IgE and IgG1 production and diminished IgM and IgG3 synthesis. We also show that PGE and cholera toxin elevate intracellular cAMP in B lymphocytes in a dose-dependent manner. In contrast, PGF2 alpha (10(-6) M) and the B subunit of cholera toxin (100 pg/ml) did not increase cAMP and did not regulate the isotype of Ig produced, reiterating the importance of cAMP in enhancing isotype differentiation. Although PGE is known to inhibit a number of immune responses, our data show that it is not always inhibitory. PGE may play a role in atopy in vivo where PGE-secreting cells such as macrophages, follicular dendritic cells, and fibroblasts can promote IgE synthesis. This research emphasizes the importance of PGE in regulation of the humoral immune response and adds a new stimulatory action to the repertoire of known PGE effects.
Alprostadil↗
Analytical study of phosphorothioate analogues of oligodeoxynucleotides using high-performance liquid chromatography.
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Chromatography, High Pressure Liquid↗
Proteoglycans synthesized by human glomerular mesangial cells in culture.
Human fetal kidney mesangial cells were cultured for 24 h in the presence of 3H-amino acids and [35S] sulfate and chased for 24 h in nonradioactive medium. Incubation medium and cell layer proteoglycans were purified twice by high performance liquid chromatography-DEAE chromatography followed by gel filtration chromatography. The major medium 35S-macromolecules were chondroitin/dermatan-35SO4 proteoglycans. A small, Sepharose CL-6B Kav 0.14 dermatan-35SO4 proteoglycan was detected in the labeling medium and was released into both the early (time 0-0.5 h) and late (6-24 h) chase media. It contained 38 kDa 4-sulfated 35S-GAGs with a high content of iduronic acid and a 45-kDa protein core. A protein core of similar molecular weight was detected in the culture medium by Western analysis using antibodies to biglycan or proteoglycan-I (Fisher, L. W., Termine, J. D., and Young, M. F. (1989) J. Biol. Chem. 264, 4571-4576). This 35S-proteoglycan was not detected in the cell layer. However, a small dermatan-35SO4 with little or no protein core was present in the intracellular compartment. A large, Sepharose CL-6B excluded chondroitin-35SO4 proteoglycan was released into the culture medium and was detected between 6 and 24 h in chase medium. It eluted near the void volume of both associative and dissociative Sepharose CL-4B columns. It contained 30-kDa 4- and 6-sulfated 35S-GAGs and a 253-kDa protein core. A chondroitin-35SO4 proteoglycan with similar sized 35S-GAGs was detected in both the detergent-soluble and insoluble cell layer compartments. A Sepharose CL-6B Kav 0.11 heparin-35SO4 proteoglycan with a 220-kDa protein core and 38-kDa 35S-GAGs was rapidly released from the cell layer. This proteoglycan was larger than that previously described in isolated rat glomeruli or glomerular basement membranes, but had a core protein similar in size to one previously detected in these tissues. A larger heparan-35SO4 proteoglycan with larger 35S-GAGs was present in the detergent-insoluble cell layer compartment. The proteoglycans released by glomerular mesangial cells in culture resembled those synthesized by aortic smooth muscle cells in culture or extracted from aorta, supporting the notion that these cells are of vascular origin.
Blotting, Western↗
Impaired chemotactic responses of bronchoalveolar leukocytes in experimental pneumoconiosis.
Rats were exposed to clouds of the following pneumoconiotic dusts: quartz, coal-mine dust, and chrysotile asbestos at 10 or 50 mg/m3 for 8, 32, and 75 days; for comparison, rats were also exposed to the non-pathogenic dust titanium dioxide (TiO2). The bronchoalveolar leukocytes (macrophages and neutrophils) from dust-exposed and control rats were obtained by lavage and tested for their ability to migrate toward zymosan-activated serum. Varying amounts of neutrophils were present depending on the ability of the dust to cause inflammation and the length of exposure. There was a marked loss of chemotactic ability in leukocytes from rats inhaling the pneumoconiotic dusts compared with controls; TiO2-exposed leukocytes had some impairment of chemotaxis, but this was substantially less than that found with the pneumoconiotic dusts. The loss of chemotactic activity did not correlate with the percentage of neutrophils in the lavage cells except when there were very high levels of neutrophils, and there was substantial impairment of chemotaxis with negligible numbers of neutrophils, showing that macrophage chemotaxis was impaired. A phagocytic burden within the leucocytes was not sufficient alone to inhibit chemotaxis, nor was the loss of chemotactic activity due to occupied receptors, since incubation failed to restore chemotaxis. Loss to chemotactic activity by leukocytes from pneumoconiotic dust-exposed lung could be an important factor in the development of pneumoconiosis.
Animals↗