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D Brown

Publications and source records attributed to D Brown.

At least 469 records · Page 26Linked to original sources
PubMed1995

The in vivo pharmacological profile of a 5-HT1 receptor agonist, CP-122,288, a selective inhibitor of neurogenic inflammation.

1. The aim of the present study was to investigate the in vivo pharmacological profile of CP-122,288, an indole-derivative with a conformationally restricted N-methylpyrrolidinyl basic side chain in the C-3 position. This C-3 substituent structurally differentiates CP-122,288 from the 5-HT1D receptor agonist sumatriptan, which possesses an N,N-dimethylaminoethyl group. [Formula: see text] 2. When administered prior to electrical stimulation of the trigeminal ganglion, CP-122,288 (0.3-300 ng kg-1, i.v.) produced a dose-related inhibition of plasma protein extravasation in rat dura mater (minimum effective dose, MED, 3 ng kg-1 i.v., P < 0.05; maximal inhibition of plasma extravasation at 30 ng kg-1 i.v., P < 0.01). Sumatriptan produced a similar inhibition of plasma leakage in the dura, but at much higher dose levels (MED, 100 micrograms kg-1 i.v., P < 0.05). Thus, CP-122,288 is of the order of 10(4) fold more potent than sumatriptan. 3. At all doses tested, CP-122,288 did not inhibit plasma protein extravasation measured in extracranial tissues such as the lower lip, eyelid, and conjunctiva. 4. In a separate series of studies in the anaesthetized rat, CP-122,288 (0.003-3 micrograms kg-1 i.v.) produced no change in either heart rate or mean arterial blood pressure, thus demonstrating that doses of CP-122,288 which inhibit plasma protein leakage in rat dura, are devoid of hemodynamic effects. 5. Following a 5 min period of electrical stimulation of the trigeminal ganglion, a 20 min period of sustained neurogenically-driven plasma extravasation, occurring in the absence of electrical stimulation, was initiated. By administration of the compound 5 min after completing the phase of electrical stimulation, this protocol permitted the evaluation of the activity of CP-122,288 on an ongoing and established inflammatory event. CP-122,288 (30 and 300 ng kg-1, i.v., P < 0.01 and P < 0.05, respectively) produced a complete inhibition of plasma protein leakage which was consistent with its effects when administered prior to trigeminal ganglion stimulation. 6. In the anaesthetized dog, CP-122,288 and sumatriptan, at 1-300 micrograms kg-1, i.v., produced a dose-dependent reduction in carotid arterial blood flow and coronary arterial diameter. These data demonstrate that sumatriptan inhibits neurogenic inflammation in the rat (MED, 100 micrograms kg-1, i.v.), and produces vasoconstriction in the dog, over a similar dose-range. Interestingly, doses of CP-122,288 that inhibit neurogenic inflammation in rat dura mater (0.3-300 ng kg-1) were demonstrated to be devoid of vasoconstrictor activity in either the carotid or coronary vascular beds of dog. 7. These data demonstrate that in the rat, CP-122,288 is a highly potent and selective inhibitor of neurogenic inflammation in intracranial tissues, at doses which are devoid of vasoconstrictor activity in dog. Potentially, CP-122,288 may be of use for the acute treatment of migraine, without the risk of cardiovascular side-effects.

Anesthesia↗
PubMed1995

Significance of systemic endotoxaemia in inflammatory bowel disease.

Quantitative and qualitative disturbances in faecal flora suggest a role for enteric bacteria and their products in the pathogenesis of inflammatory bowel disease (IBD). This study investigated the hypothesis that systemically circulating endotoxins are of pathogenic significance in IBD by measuring antibody, cytokine, and acute phase protein responses. Systemic endotoxaemia was found in 88% patients with ulcerative colitis (n = 25) and 94% with Crohn's disease (n = 31) during clinical relapse. Systemic endotoxaemia correlated positively with anatomic extent and clinical activity of ulcerative colitis. Circulating tumour necrosis factor (TNF) was detected in 40% of patients with ulcerative colitis and 45% with Crohn's disease. Plasma TNF concentrations correlated with clinical and laboratory measures of disease activity and were associated with a surgical outcome to the disease episode. Plasma soluble TNF receptor p55 concentration correlated positively with disease activity and endotoxin core antibody concentrations. Plasma IgG endotoxin core antibody concentrations were significantly increased in patients with Crohn's disease and correlated with systemic endotoxaemia. The presence of systemic endotoxaemia, its correlation with disease activity, disease extent, and endotoxin core antibody concentration and the detection of circulating TNF and soluble TNF receptors all support a pathogenic role for endotoxins in IBD.

Adolescent↗
PubMed1995

Immunolocalization of aquaporin CHIP in the guinea pig inner ear.

Aquaporin CHIP (AQP-CHIP) is a water channel protein previously identified in red blood cells and water transporting epithelia. The inner ear is an organ of hearing and balance whose normal function depends critically on maintenance of fluid homeostasis. In this study, AQP-CHIP, or a close homologue, was found in specific cells of the inner ear, as assessed by immunocytochemistry with the use of affinity-purified polyclonal antibodies against AQP-CHIP.AQP-CHIP was predominantly found in fibrocytes in close association with bone, including most of the cells lining the bony labyrinth and in fibrocytes lining the endolymphatic duct and sac. AQP-CHIP-positive cells not directly apposing bone include cells under the basilar membrane, some type III fibrocytes of the spiral ligament, fibrocytes of the spiral limbus, and the trabecular perilymphatic tissue extending from the membranous to the bony labyrinth. AQP-CHIP was also found in the periosteum of the middle ear and cranial bones, as well as in chondrocytes of the oval window and stapes. The distribution of AQP-CHIP in the inner ear suggests that AQP-CHIP may have special significance for maintenance of bone and the basilar membrane, and for function of the spiral ligament.

Animals↗
PubMed1995

Ecto-adenosinetriphosphatase in rat small intestinal brush-border membranes.

Antibodies against the holo ecto-adenosinetriphosphatase (ATPase) of rat liver and antibodies against COOH-terminal peptides of the long isoform of this enzyme reacted in Western blots with a 105-kDa band from small intestinal brush-border membranes. Indirect immunofluorescence revealed reactive proteins predominantly at the apical surface of enterocytes with some staining of basolateral membranes and of vascular endothelium. Similar results were obtained with monoclonal antibodies against HA4, a protein from rat liver closely related to the ecto-ATPase. Since these results suggested the presence of an ecto-ATPase, ATP hydrolysis was studied in intact, right-side-out brush-border membrane vesicles. Nearly half of ATP hydrolysis was caused by alkaline phosphatase (AP). Besides purine and pyrimidine trinucleotides, AP also hydrolyzed ADP, AMP, pyrophosphate, and 4-nitrophenylphosphate. Inactivation of AP by cleavage of its membrane anchor and by removal of the Zn2+ necessary for its function left the ecto-ATPase that was activated by Ca2+ and Mg2+ and hydrolyzed purine and pyrimidine trinucleotides and dinucleotides, but not AMP, pyrophosphate, and 4-nitrophenylphosphate. These features are characteristic of an ATP diphosphohydrolase (EC 3.6.1.5, also called apyrase). The physiological role of the small intestinal ecto-ATPase may be the degradation of nutrient nucleotides.

Adenine Nucleotides↗
PubMed1995

Water channel expression in human ADPKD kidneys.

Cyst enlargement in autosomal dominant polycystic kidney disease (ADPKD) results in part from the transport of solute and fluid into the lumen of the cyst. In proximal tubules and thin descending limbs of normal kidneys, the high transepithelial water permeability of these segments is due to the presence of the water channel protein, aquaporin-CHIP (AQP-CHIP, i.e., AQP-1). The collecting ducts of normal kidneys express another member of this gene family, the aquaporin collecting duct (AQP-CD, i.e., AQP-2). The expression and distribution of these two members of the aquaporin gene family were examined in ADPKD and normal human kidneys. In both tissues, Western blotting with the anti-AQP-CHIP antibody revealed a major 28-kDa band. By immunofluorescence, AQP-CHIP was present in proximal tubules and thin descending limbs of Henle of both normal and ADPKD kidneys. In the latter, AQP-CHIP was detected in the epithelia lining 71% of cysts. Many cysts were positive for the proximal tubule marker gp330 (44%). Some cysts expressing AQP-CHIP did not stain for gp330, suggesting a descending thin limb origin, and a few cysts were negative for both markers. In normal human kidney, Western blotting with the anti-AQP-CD antibody revealed a band at 28 kDa. AQP-CD was localized to collecting ducts and did not show colocalization with gp330 in normal human kidney. In ADPKD kidney, AQP-CD was expressed by only 8% of cysts. In summary, water channels, primarily AQP-CHIP, are expressed in epithelial cells lining cysts in approximately 80% of cysts in ADPKD kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Temperature-sensitive SV40 immortalized rat proximal tubule cell line has functional renin-angiotensin system.

Immortalized rat proximal tubule cell (IRPTC) lines should be useful for investigation of proximal tubule (PT) regulation and function but previously have been unavailable. We now report the establishment and characterization of an immortalized transformed, temperature-sensitive IRPTC cell line containing renin-angiotensin system (RAS) components. Primary PT cells prepared from male Wistar rats (4-5 wk old) after collagenase digestion, sieving, and Percoll gradient were cultured on collagen-coated T-75 flasks in Dulbecco's modified Eagle's medium containing 5% fetal calf serum. Subconfluent PT cells were transfected with the temperature-sensitive SV40 mutant viruses (tsA SV40) by direct exposure. After 7-8 wk, several clones were obtained, from which one has been characterized and designated as line 3-2. This cell line appears stable up to 45 passages. Clonal cells transformed with this virus exhibit a transformed phenotype at a permissive temperature of 34 degrees C and grow in multiple layers. When the cells are subsequently placed at a nonpermissive temperature of 41 degrees C, they return to morphology similar to that of untransformed cells of the same lineage. At either 34 degrees C or 41 degrees C, this cell line expresses a variety of PT markers including alkaline phosphatase, cytokeratin, carbonic anhydrase, and glucose transporter isoform 2 (GLUT2), while not expressing factor VIII. Uniquely, these cells also appear to express PT proteins gp330 and CHIP28, markers which are usually lost in cultured cells. Furthermore, the cell line expresses protein and mRNA components of RAS, including angiotensinogen, angiotensin converting enzyme, and renin. The IRPTC cell line expresses few angiotensin II (ANG II) receptors at 34 degrees C, the permissive temperature. However, at the nonpermissive temperature, 41 degrees C, IRPTC expresses ANG II receptor (dissociation constant of 0.7 nM; maximum binding capacity of 265 fmol/mg protein). ANG II (10(-8) M) induced a transient rise in cytoplasmic Ca2+ concentration, which was nearly abolished with losartan but not PD-123319, suggesting this finding is AT1 receptor mediated. This cell line should provide an excellent model of PT and should make it possible to study the cell and molecular biology of the RAS, as well as other regulatory systems of the PT.

Animals↗
PubMed1995

Depletion of intercalated cells from collecting ducts of carbonic anhydrase II-deficient (CAR2 null) mice.

The kidneys of mice (CAR2-null mice) that are genetically devoid of carbonic anhydrase type II (CAII) were screened by immunocytochemistry with antibodies that distinguish intercalated and principal cells. Immunofluorescent localization of the anion exchanger AE1 and of the 56-kDa subunit of the vacuolar H(+)-adenosinetriphosphatase (H(+)-ATPase) was used to identify intercalated cells, while the AQP2 water channel was used as a specific marker for principal cells of the collecting duct. The CAII deficiency of the CAR2-null mice was first confirmed by the absence of immunofluorescent staining of kidney sections exposed to an anti-CAII antibody. Cells positive for AE1 and H(+)-ATPase were common in all collecting duct regions in normal mice but were virtually absent from the inner stripe of the outer medulla and the inner medulla of CAR2-null mice. The number of positive cells was also reduced threefold in the cortical collecting duct of CAR2-null animals compared with normal mice. In parallel, the percentage of AQP2-positive cells was correspondingly increased in the collecting tubules of CAII-deficient mice, whereas the total number of cells per tubule remained unchanged. These results suggest that intercalated cells are severely depleted and are replaced by principal cells in CAII-deficient mice. Quantitative analysis and double staining showed that, in the cortex, both type A and type B intercalated cells are equally affected. Elucidation of the mechanism(s) responsible for this phenotype will be of importance in understanding the origin and development of intercalated cells in the kidney.

Animals↗
PubMed1995

The role of tumor necrosis factor in increased airspace epithelial permeability in acute lung inflammation.

Increased airspace epithelial permeability is an early event in lung inflammation and injury. In this study, we have developed a rat model to study the mechanisms of the epithelial permeability to 125iodine-labeled bovine serum albumin (125I-BSA), instilled intratracheally during acute lung inflammation. Epithelial permeability was measured as the percentage of instilled 125I-BSA appearing in the blood. The increase in epithelial permeability induced by intratracheal instillation of heat-killed Corynebacterium parvum produced a peak influx of neutrophils into the bronchoalveolar space at 16 h, which occurred after the peak increase in epithelial permeability (8 h). The increased epithelial permeability induced by C. parvum did not appear to be protease- or oxidant-mediated. Depletion of peripheral blood neutrophils was achieved by an intravenous injection of anti-neutrophil polyclonal antibody. The consequent profound reduction in neutrophil and macrophage influx into the airspaces 8 h after instillation of C. parvum reduced the epithelial permeability to control values. Bronchoalveolar lavage (BAL) leukocytes from rats 8 h, but not 16 h, after treatment with C. parvum caused a modest increase in epithelial permeability when re-instilled intratracheally into control rat lungs. Separation of the leukocytes before re-instillation indicated that macrophages rather than neutrophils were predominantly responsible for the increased epithelial permeability. The presence of dramatically increased levels of tumor necrosis factor (TNF) in BAL 8 h in contrast to a slight increase in BAL 16 h after C. parvum, the release of TNF from 8 h macrophages, the increased epithelial permeability induced by TNF in epithelial monolayers in vitro, and the inhibition of C. parvum-induced epithelial permeability by TNF antibody support the premise that TNF is a major player in the increased epithelial permeability that occurs during C. parvum-induced acute alveolitis.

Acute Disease↗
PubMed1995

Scleraxis: a basic helix-loop-helix protein that prefigures skeletal formation during mouse embryogenesis.

Members of the basic helix-loop-helix (bHLH) family of transcription factors have been shown to regulate growth and differentiation of numerous cell types. Cell-type-specific bHLH proteins typically form heterodimers with ubiquitous bHLH proteins, such as E12, and bind a DNA consensus sequence known as an E-box. We used the yeast two-hybrid system to screen mouse embryo cDNA libraries for cDNAs encoding novel cell-type-specific bHLH proteins that dimerize with E12. One of the cDNAs isolated encoded a novel bHLH protein, called scleraxis. During mouse embryogenesis, scleraxis transcripts were first detected between day 9.5 and 10.5 post coitum (p.c.) in the sclerotome of the somites and in mesenchymal cells in the body wall and limb buds. Subsequently, scleraxis was expressed at high levels within mesenchymal precursors of the axial and appendicular skeleton and in cranial mesenchyme in advance of chondrogenesis; its expression pattern in these cell types foreshadowed the developing skeleton. Prior to formation of the embryonic cartilaginous skeleton, scleraxis expression declined to low levels. As development proceeded, high levels of scleraxis expression became restricted to regions where cartilage and connective tissue formation take place. Scleraxis bound the E-box consensus sequence as a heterodimer with E12 and activated transcription of a reporter gene linked to its DNA-binding site. The expression pattern, DNA-binding properties and transcriptional activity of scleraxis suggest that it is a regulator of gene expression within mesenchymal cell lineages that give rise to cartilage and connective tissue.

Amino Acid Sequence↗
PubMed1995

Localization of MIWC and GLIP water channel homologs in neuromuscular, epithelial and glandular tissues.

It was shown recently that water channel homologs MIWC (mercurial insensitive water channel) and GLIP (glycerol intrinsic protein) colocalized in basolateral membranes of kidney collecting duct, tracheal and colonic epithelia, and in brain pia mater. We report here an extensive immunolocalization study of MIWC and GLIP in non-epithelial and glandular epithelial tissues in rat. Immunogold electron microscopy confirmed colocalization of MIWC and GLIP in basolateral membrane of principal cells in kidney collecting duct. However, in other epithelia, MIWC but not GLIP was expressed in basolateral membrane of parietal cells in stomach, and in excretory tubules of salivary and lacrimal glands; GLIP but not MIWC was expressed in transitional epithelium of urinary bladder and skin epidermis. In the central nervous system, MIWC was strongly expressed in the ependymal layer lining the aqueductal system, and in astrocytes throughout the spinal cord and in selected regions of brain. MIWC was also expressed in a plasma membrane pattern in skeletal, but not smooth or cardiac muscle. Neither protein was expressed in small intestine, testis, liver, spleen and nerve. The tissue-specific expression of MIWC suggests a role in fluid transport and/or cell volume regulation in stomach and glandular epithelia. The functional role of MIWC expression in the neuromuscular system and of GLIP expression in skin and urinary bladder is uncertain. The specific cellular sites of MIWC expression (astrocytes, trachea, sarcolemma, gastric parietal cells and kidney principal cells) correspond exactly to sites where orthogonal arrays of particles (OAPs) have been visualized by freeze-fracture electron microscopy, suggesting that MIWC may be the OAP protein.

Amino Acid Sequence↗
PubMed1995

Silicosis among gold miners: exposure--response analyses and risk assessment.

OBJECTIVES: This study sought to estimate the risk of silicosis by cumulative exposure-years in a cohort of miners exposed to silica, as well as the lifetime risk of silicosis under the current Occupational Safety and Health Administration (OSHA) standard (0.09 mg/m3). METHODS: In a cohort study of 3330 gold miners who worked at least 1 year underground from 1940 to 1965 (average 9 years) and were exposed to a median silica level of 0.05 mg/m3 (0.15 mg/m3 for those hired before 1930), 170 cases of silicosis were determined from either death certificates or two cross-sectional radiographic surveys. RESULTS: The risk of silicosis was less than 1% with a cumulative exposure under 0.5 mg/m3-years, increasing to 68% to 84% for the highest cumulative exposure category of more than 4 mg/m3-years. Cumulative exposure was the best predictor of disease, followed by duration of exposure and average exposure. After adjustment for competing risks of death, a 45-year exposure under the current OSHA standard would lead to a lifetime risk of silicosis of 35% to 47%. CONCLUSIONS: Almost 2 million US workers are currently exposed to silica. Our results add to a small but increasing body of literature that suggests that the current OSHA silica exposure level is unacceptably high.

Adult↗
PubMed1995

A transgenic mouse model provides a novel biological assay of topical glucocorticosteroid potency.

BACKGROUND AND DESIGN: A homozygous line of transgenic mice that expresses the human elastin promoter/CAT (chloramphenicol acetyltransferase) reporter gene construct in a tissue-specific and developmentally regulated manner is presented. Previous studies have shown that subcutaneous injections of various glucocorticosteroids up-regulate the human transgene in the mouse skin potentially through their interaction with three putative glucocorticosteroid-responsive elements contained within the human elastin promoter. In this study, we propose the use of these transgenic mice as a model system for assaying the potency of various topical glucocorticosteroid preparations. RESULTS: In the first set of experiments, three different commercially available topical glucocorticosteroid creams, 2.5% Hytone (2.5% hydrocortisone) (Dermik Laboratories, Fort Washington, Pa), Cutivate (0.05% fluticasone propionate) (Glaxo Inc, Research Triangle Park, NC), and Temovate (0.05% clobetasol propionate) (Glaxo Inc) (being classified into class VII, V, and I steroids, respectively) were applied to the skin of transgenic mice, with Eucerin (Beiersdorf Inc, Lindenhurst, NY) as the control cream. In a series of six experiments, Hytone 2.5% cream caused a 3.1-fold increase on the average, with Cutivate and Temovate creams resulting in 2.2-fold and 12.4-fold increases in CAT activity over control, respectively. Next, two different preparations of diflorasone diacetate 0.05% cream (Florone [class III] and Psorcon [class II], both from Dermik Laboratories), formulated with different vehicles, were compared. Psorcon caused a 22.8-fold increase in CAT activity over the control compared with a 4.4-fold increase for Florone. However, an assay comparing Psorcon ointment (class I) and Psorcon cream (class II) showed no statistically significant difference in their potencies. CONCLUSIONS: These preliminary findings suggest the usefulness of these transgenic mice as a model system for assaying the potency of topical glucocorticosteroid preparations. Discrepancies between our data and the published classification of some topical steroids may result from anatomic differences between human and murine skin, with mouse skin much thinner, Alternatively, the discrepancies may reflect the fact that our assay measures the biological activity of these steroids on gene transcription, while previous ranking is based on their vasoconstrictive activity.

Administration, Topical↗
PubMed1995

Parkinson's disease: drug-induced psychiatric states.

Drug-induced psychiatric states occur frequently in PD. In the prelevodopa era, depression and other psychiatric disorders were described in PD, but in untreated patients psychosis was rare. Since the development of levodopa and other pharmacological treatments for PD, however, psychotic symptoms have become much more common (10-50%). In some individuals these problems can be more disabling than the motor features of PD and, as a result, pose a serious threat to the patient's ability to maintain independence. The drug-induced psychoses consist of several distinct psychiatric syndromes that can be divided broadly into those occurring on a background of a clear sensorium and those which are accompanied by confusion and clouding of consciousness. Benign organic hallucinosis is the most common of these syndromes (30%). It usually occurs on a background of a clear sensorium and may not be a particularly troublesome problem if the patient is able to retain insight into the nature of these symptoms. More disabling syndromes usually include delusional thinking that is frequently paranoid, confusion and even frank delirium. Although all these psychotic syndromes can occur in isolation, there is a tendency for mild symptoms to progress to more disabling ones if adequate and timely treatment is not instituted. Abnormal dreaming and sleep disruption often precede these difficulties by weeks to months and may provide an important early clue to their onset. The mechanisms responsible for drug-induced psychotic symptoms in PD are unknown, but dopaminergic (especially mesolimbic) and serotoninergic systems are likely to be involved. The treatment of the drug-induced psychoses in PD should be undertaken in a stepwise manner. A detailed discussion of this approach, including the use of anti-PD medication adjustment, clozapine, and other medications (neuroleptic and nonneuroleptic) and ECT is provided (see Fig. 1). Although drug-induced psychoses are the most important of the drug-induced psychiatric states, mania, anxiety, and hypersexuality may also occur. Depression is also common in PD, but it is unlikely to occur as a side effect of antiparkinsonian medications.

Aged↗
PubMed1995

Smiling and fussing in seven-month-old preterm and full-term black infants in the still-face situation.

We investigated emotional responses to the still-face paradigm in 7-month-old preterm and full-term black infants. Baby FACS criteria were used to code the duration and intensity of infant smiles and the presence or absence of cry faces and fussy vocalizations within each episode. Infants in both groups showed the still-face effect: a significant reduction in smiling from episode 1 (baseline) to episode 2 (maternal still-face) and partial return to baseline in episode 3 (recovery). A multivariate analysis of covariance (MANCOVA) for big smiles yielded significant main effects for group and episode and a significant group x episode interaction. Preterm infants spent less time than full-term infants displaying big smiles in episode 1 and a less pronounced decrease in big smiles in episode 2. Maternal depressive symptoms did not differ significantly between groups. Counter to our expectations, depressive symptoms were positively associated with small-to-medium smiles in the baseline episode but not with big smiles in any episode. These findings confirm the robustness of the still-face paradigm and its potential usefulness for research on individual as well as group differences in affective communication in infants.

Affect↗
PubMed1995

The use of pramipexole, a novel dopamine (DA) agonist, in advanced Parkinson's disease.

We evaluated the efficacy, safety and tolerability of a new dopamine D-2 receptor agonist, pramipexole [(S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzathiazol-dihydro chloride], as adjunctive therapy in patients with advanced Parkinson's disease (PD). Twenty-four PD patients with motor fluctuations were treated in an 11 week prospective, single-blind parallel-group, placebo-controlled trial. The pramipexole treated group experienced a significant improvement in "off" time functioning as measured by the activities of daily living portion of the United Parkinson's Disease Rating Scale. In addition, the active treatment group was able to reduce total levodopa dose by 30% (p < 0.05). Pramipexole was well tolerated and the side effects reported were typical of other dopamine agonists. We conclude that pramipexole has antiparkinsonian effects which make it potentially useful in the treatment of motor fluctuations in PD.

Aged↗