Search PubMed⌕ Search

Biomedical subjects

J Dawson

Publications and source records attributed to J Dawson.

232 records · Page 13Linked to original sources
PubMedDate not supplied

Gastrointestinal metabolism of N-acetylcysteine in the rat, including an assay for sulfite in biological systems.

The intestinal metabolism of N-acetylcysteine was studied in the rat. Isolated intestinal epithelial cells were shown to rapidly deacetylate [14C]-N-acetylcysteine to [14C]-cysteine, with slight oxidation of the latter to disulfide species. The cells did not accumulate reduced or oxidized cysteine, and N-acetylcysteine itself was not detected either free or in oxidized species intracellularly. Further metabolism of this NAC-derived cysteine to inorganic sulfite or glutathione was not detected. Following the administration of [14C]-N-acetylcysteine (50 mg/kg; 25 microCi) in vivo into the ilium, small quantities of both reduced and oxidized [14C]-N-acetylcysteine were demonstrated in hepatic portal vein plasma. [14C]-cysteine and inorganic sulfite were demonstrated as the major metabolites of N-acetylcysteine. These were present in the portal vein plasma at levels five and three times greater than the parent drug, respectively, 30 min after dosing. Additionally, [14C]-glutathione was shown to be a minor metabolite of N-acetylcysteine accumulating in portal vein plasma. These results may provide an explanation for the apparent low bioavailability of N-acetylcysteine when administered orally in humans and are discussed in terms of the origins of the protective effect of the drug in cases of paracetamol intoxication in humans.

Acetylcysteine↗
PubMedDate not supplied

Xanthone additives for blood storage that maintain its potential for oxygen delivery. I. 2-Hydroxyethoxy- and 2-ethoxy-6-(5-tetrazoyl) xanthones in citrate-phosphate-dextrose-adenine (CPDA-1) blood.

Two xanthones, 2-hydroxyethoxy-6-(5-tetrazoyl) (BW A440C) and 2-ethoxy-6-(5-tetraozyl) (BW A827C), are members of a chemical series tested in vitro as potential additives to citrate-phosphate-dextrose-adenine (CPDA-1) medium for blood storage. P50 was maintained in the presence of these compounds during 42 days' storage by a partial maintenance of 2,3 diphosphoglycerate (2,3 DPG) and by a direct effect on hemoglobin previously reported for BW A827C. Red cell 2,3 DPG levels for BW A440C (n = 5), BW A827C (n = 5), and control (n = 6), respectively, were 3.38 +/- 0.47, 3.44 +/- 0.25, and 1.20 +/- 0.10 mM +/- SEM on day 7; 1.16 +/- 0.13, 1.52 +/- 0.37, and 0.16 +/- 0.02 mM on day 21; and 0.67 +/- 0.09, 0.61 +/- 0.08, and 0.06 +/- 0.006 mM on day 42. Red cell adenine triphosphate levels at the same time intervals were 1.84 +/- 0.09, 1.46 +/- 0.18, and 2.11 +/- 0.04 mM; 2.10 +/- 0.05, 2.07 +/- 0.17, and 2.13 +/- 0.05 mM; and 1.42 +/- 0.13, 1.37 +/- 0.13, and 1.38 +/- 0.06 mM, respectively. The degree of hemolysis was less with the addition of the compounds, and the methemoglobin formation, plasma Na+ and K+, and lactate production were unaffected by the compounds.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Wound healing in partial-thickness burn wounds treated with collagenase ointment versus silver sulfadiazine cream.

During burn care the wounds must be repeatedly debrided of adherent and loose debris until the decision is made to surgically excise and graft the wound or to await epithelialization. Though native proteolytic enzymes in the skin or those produced by colonizing bacteria can speed eschar separation, the use of exogenous enzymes for wound debridement may accelerate wound cleaning and healing. Collagenase digests native and denatured collagen in necrotic tissue. This multicenter trial of 79 patients with partial-thickness wounds compared the efficacy of collagenase ointment applied with polymyxin B sulfate/bacitracin powder with the efficacy of standard topical antimicrobial therapy (control) in which silver sulfadiazine cream (1%) was used to debride paired burn sites. Patients selected for the study had two noncontiguous, partial-thickness, comparably sized, and anatomically similar burn wounds. Ages of patients ranged from 5 to 60 years (mean 33 years). The total body surface area burned ranged from 2% to 30% (mean 13.6%). Mean burn sizes used for study treatment were 366 cm2 (26 to 2310 cm2) for collagenase sites and 355 cm2 (26 to 2394 cm2) for control sites. Sites on each patient were randomly assigned to treatment with either collagenase or control. Endpoints were time to clean wound bed (absence of retained debris) and time to healing (complete epithelialization). The sites treated with collagenase cleaned in less time (mean 9.3 days) than the control sites (mean 11.6 days). Similarly the collagenase sites healed faster than the control sites (mean 19 vs 22.1 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMedDate not supplied

Pathologic studies of fatal cases in outbreak of hand, foot, and mouth disease, Taiwan.

In 1998, an outbreak of enterovirus 71-associated hand, foot, and mouth disease occurred in Taiwan. Pathologic studies of two fatal cases with similar clinical features revealed two different causative agents, emphasizing the need for postmortem examinations and modern pathologic techniques in an outbreak investigation.

Disease Outbreaks↗
PubMedDate not supplied

Staphylococcus aureus bacteremia: the cost-effectiveness of long-term therapy associated with infectious diseases consultation.

OBJECTIVE: To investigate the cost-effectiveness of long-term therapy for Staphylococcus aureus bacteremia and to determine if an infectious diseases consultation affected the duration of therapy. METHODS: A decision analysis was performed based on data from the literature. To determine if consultation was related to therapy duration, a retrospective cohort study was performed using tightly matched pairs. RESULTS: The excess cost per life saved by long-term antibiotics was $500,000. The excess cost per life-year saved was $18,000. Nine pairs were matched. Patients who received consultation were more likely to receive long-term therapy than controls (median 41 days vs 15 days for controls, P = .04). CONCLUSIONS: The estimated cost per life-year saved by long-term therapy was similar to other accepted medical interventions. Infectious diseases consultation can encourage prolonged duration of antibiotic therapy for S aureus bacteremia.

Anti-Bacterial Agents↗
PubMedDate not supplied

Proning patients in intensive care.

Patients with acute lung injury pose significant problems for the intensive care team. The use of the prone position with these patients is attracting increasing interest. Information on the practicalities of proning was obtained from other intensive care units by using a simple questionnaire. The necessity for nursing guidelines for proning is discussed, and the consequent development of these is described.

Blood Gas Analysis↗
PubMedDate not supplied

Suppression of natural killer cell activity by hydrocortisone.

The in vitro effect of physiological levels of hydrocortisone (HC) on NK activity of human lymphocytes was investigated. Lymphocytes incubated with HC 20-80 micrograms/dl (200-800 ng/ml) prior to NK assay showed depressed NK activity similar to that previously reported at higher doses. The responsiveness of NK cells to augmentation by alpha and gamma interferon was also appreciably depressed by HC. Inhibition of cytotoxicity was not due to a toxic effect of the drug since the viability of the effector cells after incubation was comparable to control cells. Indomethacin was able to partially reverse hydrocortisone suppression in 7 out of 12 experiments. Results of these in vitro studies demonstrate that hydrocortisone, when used at the levels found in humans treated with interferon, could have significant immunomodulatory effects that would be expected to alter the immunostimulation induced by the interferons.

Cytotoxicity Tests, Immunologic↗