Biomedical subjects

S A Greenacre

Publications and source records attributed to S A Greenacre.

4 recordsLinked to original sources

PubMed2001

Tyrosine nitration: localisation, quantification, consequences for protein function and signal transduction.

The nitration of free tyrosine or protein tyrosine residues generates 3-nitrotyrosine the detection of which has been utilised as a footprint for the in vivo formation of peroxynitrite and other reactive nitrogen species. The detection of 3-nitrotyrosine by analytical and immunological techniques has established that tyrosine nitration occurs under physiological conditions and levels increase in most disease states. This review provides an updated, comprehensive and detailed summary of the tissue, cellular and specific protein localisation of 3-nitrotyrosine and its quantification. The potential consequences of nitration to protein function and the pathogenesis of disease are also examined together with the possible effects of protein nitration on signal transduction pathways and on the metabolism of proteins.

Animals↗

PubMed2000

Generation of peroxynitrite in localised, moderate temperature burns.

Simultaneous generation of nitric oxide (NO*) and superoxide (O2-) can lead to the formation of peroxynitrite (ONOO-), a potent oxidant that has been implicated in the pathogenesis of a number of disease states. This study was designed to investigate the possible generation of ONOO- in local cutaneous tissues following thermal injury. Male Wistar rats were anaesthetised in a nonrecovery procedure and subjected to a small (1 cm diameter), abdominal burn of moderate temperature (50 degrees C, 5-15 min). At either the 60 or 180 min time point postburn the animals were killed, and skin sites were removed and homogenised. An ELISA was used to quantify protein bound 3-nitrotyrosine (3NT), a biomarker for ONOO- in the rat skin. In separate experiments the accumulation of [125I]-albumin in thermally injured skin was used to calculate plasma extravasation. Thermal injury (50 degrees C, 10 min) to rat abdominal skin caused a significant increase in both 3NT (p < 0.05) and oedema formation (p < 0.001) when compared to unheated control sites at the 180 min time point postburn. This data is the first to show protein nitration in thermally injured, oedematous skin and strongly suggests that ONOO- is generated in thermally damaged cutaneous tissue.

Animals↗

PubMed1999

Formation and loss of nitrated proteins in peroxynitrite-treated rat skin in vivo.

Peroxynitrite is a reactive cytotoxic species, capable of nitrating tyrosine residues to form 3-nitrotyrosine. Little is known about the formation and loss of nitrated proteins in vivo. We have measured nitrated proteins, by enzyme-linked immunosorbent assay, in rat skin after exposure to peroxynitrite. Peroxynitrite (100-200 nmol site(-1)) was injected into the skin of anesthetized rats. At the highest dose 78.6 +/- 9.5 pmol mg(-1) protein of nitrated BSA equivalents were measured at 4 h and a significant increase was observed for 24 h after administration in skin samples. The loss of nitrated proteins from skin appeared biphasic with an initial (t(1/2) = 2 h) and slower loss (t(1/2) = 22 h). A major nitrated protein was identified as albumin by Western blot analysis. The data demonstrate that a single exposure to peroxynitrite can lead to the presence of nitrated proteins in skin for at least 24 h. The sustained presence of nitrated proteins may influence the inflammatory process in skin disease.

Animals↗

PubMed1997

Effect of peroxynitrite on plasma extravasation, microvascular blood flow and nociception in the rat.

1. Peroxynitrite (ONOO-) is a cytotoxic species, formed by the reaction between nitric oxide and superoxide free radicals, that may be involved in inflammation. In this study we have investigated the effect of peroxynitrite on plasma extravasation and microvascular blood flow in the dorsal skin and on nociceptive responses in the hind paw of the rat. 2. Male Wistar rats were anaesthetized and their dorsal skin shaved. Plasma extravasation was measured by the extravascular accumulation of 125I-labelled albumin over 0-45 min and 0-240 min. Blood flow was measured by laser-Doppler flowmetry over 0-240 min. Studies in the hind paw were carried out in the conscious rat. Hind paw weight changes were determined by volume displacement and nociception by a mechanical hyperalgesia technique. 3. Intradermal (i.d.) peroxynitrite (100-200 nmol site-1) produced a significant (P < 0.01) dose-dependent increase in plasma extravasation in dorsal skin over 0-45 min which was not increased over 45-240 min. Plasma extravasation was significantly (P < 0.001) decreased in rats pretreated with the anti-inflammatory steroid dexamethasone (1 mg kg-1, i.v.; -180 min), but not modulated by treatment with the hydrogen peroxide deactivator catalase (2200 u site-1), or the superoxide scavenger superoxide dismutase (500 u site-1), effective doses of the tachykinin NK1 antagonist SR140333 (1 nmol site-1), the cyclo-oxygenase inhibitor indomethacin (358 mumol site-1), or combined pretreatment with mepyramine (histamine H1-receptor antagonist; 2.8 nmol site-1) and methysergide (5-HT antagonist; 1.9 nmol site-1). 4. Microvascular blood flow was significantly (P < 0.05) increased 30 and 120 min after i.d. peroxynitrite (100 nmol site-1) in dorsal skin and remained raised until the end of the recording period (240 min). The increase in blood flow was unaffected by dexamethasone (1 mg kg-1, i.v.; -180 min) or indomethacin (10 mg kg-1, s.c.; -30 min). 5. Hind paw volume was significantly (P < 0.001) increased 30 min after intraplantar peroxynitrite (87.5 and 175 nmol paw-1) and remained raised for the duration of the experiment (360 min). By comparison, nociception was not altered by intraplantar peroxynitrite. 6. These data indicate that peroxynitrite can cause an increase in both plasma extravasation and blood flow, suggesting that peroxynitrite could be of biological relevance to microvascular responses. These findings may be of importance in the pathology of inflammatory diseases in which peroxynitrite formation occurs.

Animals↗