Publications by authors named "Pratt B"

Current hypotheses suggest that the extracellular matrix modulates cellular function in physiologic homeostasis and during injury and repair and that selected cellular functions are cell and nuclear size dependent. For elucidation of the role of extracellular matrix-driven cell size changes in the modulation of endothelial cell proliferation and sheet migration an in vitro model system was used that allows for the culture of bovine aortic endothelial cells (BAEC) on various purified extracellular matrix components. BAEC exhibited distinct patterns in rates of attachment, spreading, migration, and proliferation when cultured on the selected extracellular matrix components laminin, types I and III collagen, type IV collagen, and fibronectin.

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The avian pineal gland is a photoreceptive organ that has been shown to contain postjunctional alpha 2-adrenoceptors that inhibit melatonin synthesis and/or release upon receptor activation. Physiological response and [32P]ADP ribosylation experiments were performed to investigate whether pertussis toxin-sensitive guanine nucleotide-binding proteins (G-proteins) were involved in the transduction of the alpha 2-adrenergic signal. For physiological response studies, the effects of pertussis toxin on melatonin release in dissociated cell cultures exposed to norepinephrine were assessed.

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The incidence of Ureaplasma urealyticum in endourethral swabs was compared with that in first voided urine specimens from 171 male patients. The organism was isolated from the urethras of 72 (42%) and from the urine of 66 (39%). The interval since last voiding urine did not significantly influence the incidence of infection or ureaplasma counts in either type of specimen.

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Transforming growth factor beta (TGF-beta) is angiogenic in vivo. In vitro, endothelial cell proliferation is inhibited by TGF-beta. We have correlated this inhibitory effect with an increase in cellular fibronectin synthesis and deposition in a two-dimensional culture system using specific matrix coatings.

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Ciprofloxacin was evaluated in chlamydial infections of the urogenital tracts of women treated with a dosage regimen of 500 mg orally twice a day for seven days. Of the 40 women evaluated, 30 were infected with Chlamydia trachomatis only, two were infected with Neisseria gonorrhoeae only, and a further eight had combined gonococcal and chlamydial infections. Ten were found to be harbouring Chlamydia trachomatis in the urethra as well as the cervix.

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The chick pineal gland expresses a circadian rhythm of melatonin biosynthesis, with elevated levels at night and low levels during the day. The rhythm of melatonin is regulated both by circadian oscillators located within the gland itself and by adrenergic input from the sympathetic nervous system. Previous work has shown that norepinephrine administration inhibits melatonin biosynthesis, as measured by the activity of the enzyme serotonin N-acetyltransferase.

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The effects of extracellular matrix components on proteoheparan sulfate biosynthesis was studied for bovine aortic endothelial cells in tissue culture. When the cells were maintained on a variety of different purified components of the extracellular matrix, the cells expressed the same three species of proteoheparan sulfates as the cells cultured on tissue culture plastic (HS I, HS II, and HS III). However, the amounts of the three species recovered from the tissue culture medium were found to be dependent on the substrate on which the cells are grown as well as on other factors.

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The hepatic vitamin A-storing Ito cell has been implicated as a causative cell in hepatic fibrogenesis. Using a modification of a recent method (Friedman, S. L.

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The outcome of termination of pregnancy was observed in relation to the preoperative clinical and microbiological findings in 167 women attending a day care abortion unit in Liverpool. Before termination, Chlamydia trachomatis was isolated from the cervix of 19 (11%) of the patients and high counts (greater than 10(4) colour changing units (ccu) per ml of specimen) of mycoplasmas were found in 30 (18%). Coexistent infections with chlamydiae and high counts of mycoplasmas occurred in only seven (4%) women.

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Modulation of the behavior of microvascular endothelial cells during angiogenesis has been observed to correlate with changes in the extracellular matrix. These reports prompted a comparison of the growth of microvascular endothelial cells on monolayers of various matrix components in vitro. Over a 5 day period, the proliferation of these cells was significantly greater on laminin than on either plasma fibronectin, the interstitial collagen types I and III, or on the basement membrane collagen type IV.

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A study of four conjugal partnerships is described in which the male partners presented with persistent or recurrent non-gonococcal, non-chlamydial, but ureaplasma positive urethritis. Resolution of symptoms and signs in the male partners was achieved only after treatment to eliminate Ureaplasma urealyticum from both partners.

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The bovine aortic endothelial cell (BAEC) cytoskeleton is a complex structure modulated by many stimuli including release from contact inhibition and various components of the extracellular matrix (ECM). Transduction of information from the ECM to the cell nucleus proceeds via several complex pathways including the cytoskeleton. We have demonstrated the presence of an immunoreactive isoform of the human erythrocyte cytoskeletal protein band 4.

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Ciprofloxacin, a quinolone antibacterial, was evaluated in the treatment of gonococcal, chlamydial, gonococcal and chlamydial, and non-gonococcal non-chlamydial urethritis. The dosage regimen used was 500 mg orally twice a day for seven days. Of the 56 patients evaluated 22 had gonococcal infection only, 13 were infected with Chlamydia trachomatis only, seven had combined infection, and 14 were harbouring neither of these organisms.

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Photoperiodism and entrainment of the circadian rhythm of locomotor activity were investigated in juvenile Djungarian hamsters. Animals were housed in simulated burrows. Activity was measured as the animal's emergence from a dark nest chamber into an outer box exposed to the room illumination.

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Twenty-four Angus X Hereford steers (155 +/- 4 kg) were used to examine thyroid function during exposure to ambient temperatures of 4, 18 and 32 C. Jugular cannulae were inserted after steers were acclimated to individual stalls in environmentally controlled chambers at 18 C for 3 d. The day following cannulation, ambient temperatures were changed 2 C/h for 7 h and serum samples were collected hourly.

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The free running period (tau) of male Syrian hamsters, when measured as the circadian rhythm of emergence from simulated burrows, was compared to tau when locomotor activity was measured via running wheels. In constant darkness, the inter-individual variability of the tau s was less among burrow housed hamsters than for running wheel housed hamsters. Hence, access to activity wheels eventually led to more disparate activity onset times among the running wheel animals, as compared to the relative population synchrony observed when animals were housed in simulated burrows.

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Male Syrian hamsters were housed in simulated burrows in order to investigate (a) how these nocturnal, fossorial rodents entrain to the prevailing light:dark cycle in this semi-natural habitat and (b) the response of the reproductive system to environmental illumination. The burrow emergence activity of hamsters housed in simulated burrows was compared to the running wheel activity of animals maintained in standard cage conditions. The activity rhythm was similar in both measuring devices.

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Clenbuterol is a highly specific, long-acting (four to eight hours) beta-two sympathomimetic which causes bronchodilation and tocolysis (myometrial paralysis). The tocolytic effect was explored as a means to control parturition and reduce dystocia. Forty-six heifers were injected i.

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The extracellular matrix of adult vertebrate corneal stroma is composed primarily of the interstitial collagen type I and smaller amounts of types III and V collagen. These collagens are organized into overlapping lamellae of striated filaments. In addition to these lamellar structures, the corneal stroma also contains 100- to 250-nm bundles of nonstriated 8- to 11-nm microfibrils.

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A technique of microinjection of small quantities of teratogens into extraembryonic compartments or specific organ primordium of rat conceptuses of pregnancy day 11 is described. Conceptuses microinjected with 50 nl tissue culture medium developed normally for 44-45 hr when cultured in homologous rat serum, indicating that the microinjection procedure itself did not produce any deleterious effects on growth and differentiation of embryos. Microinjection of an alkylating agent, phosphoramide mustard dissolved in tissue culture medium, into the exocoelom produced anomalous embryogenesis, consisting of retarded embryonic growth, anomalies of the neural tube, and general necrosis of various organ primordia.

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