Biomedical subjects

S Wouters

Publications and source records attributed to S Wouters.

7 recordsLinked to original sources

PubMed2003

Recombinant human microplasmin: production and potential therapeutic properties.

The effect of recombinant human microplasmin was studied in ischemic stroke models in mice and in an extracorporeal loop thrombosis model in rabbits. Human microplasminogen ( micro Plg), which lacks the five 'kringle' domains of plasminogen was expressed with high yield in Pichia pastoris. It was purified, converted to microplasmin ( micro Pli) and equilibrated with 5 mmol L(-1) citrate, pH 3.1, yielding a stable preparation. In mice with middle cerebral artery (MCA) ligation, an intravenous (i.v.) bolus of 5.0 mg kg(-1) micro Pli reduced infarct size at 24 h from 27 (26-30) to 25 (21-28) mm3 (median and range, n= 16 each, P= 0.0001), whereas 4.0 mg kg(-1) rt-PA and 40 mg kg(-1) micro Plg had no effect. Infarct reduction was observed with administration at 4 h after occlusion. In mice with MCA, infarct size at 24 h was reduced from 20 (14-30) to 9.1 (3.1-25) mm3 with 5.0 mg kg(-1) micro Pli (n = 15 each, P < 0.002) and to 11 (5.2-27) mm3 with 4.0 mg kg(-1) rt-PA (n = 6; P= 0.02). Infarct reduction was still observed at 10 h after occlusion with micro Pli but not with t-PA. In rabbits with radiolabeled clots in an extracorporeal arteriovenous loop, local infusion of 2.5 mg kg(-1) micro Pli over 2 h, induced 51 +/- 15% lysis (mean +/- SD, n= 11) vs. a control value of 23 +/- 5.5%. micro Pli did not prolong template bleeding times, whereas equipotent doses of rt-PA were associated with extensive rebleeding. The potency of micro Pli in both models was similar to that of intact plasmin. These findings indicate that recombinant micro Pli may be useful for treatment of ischemic stroke and arterial thrombosis.

Amino Acid Sequence↗

PubMed2000

Is the apparent cardioprotective effect of recent alcohol consumption due to confounding by prodromal symptoms?

Previous research has reported a protective association between alcohol drinking and acute coronary heart disease in the 24-hour period after drinking. This study investigated whether this apparent protective association resulted from confounding due to the effect of prodromal symptoms on drinking behavior. In 1992, the authors conducted a case-control study that measured recent alcohol consumption and reasons for recent abstention from alcohol among patients with acute coronary heart disease identified from a community-based disease register and a representative control sample from the same community (Auckland, New Zealand). Cases were significantly more likely than controls to report recent abstention from drinking because they felt unwell. In unadjusted analyses, a protective association was observed between recent alcohol consumption and acute coronary heart disease; however, this association was weakened considerably after adjustment for the effect of prodromal symptoms on drinking behavior. The previously reported protective association between recent alcohol consumption and acute coronary heart disease appears to be largely due to the confounding effect of prodromal symptoms on drinking.

Alcohol Drinking↗

PubMed2000

A case-crossover analysis of a case-control study of alcohol consumption and coronary events: the effects of exposure definition and the use of control data.

BACKGROUND: Case-crossover studies can be used to assess the effects of transient exposures in acute events by comparing cases' exposures at the time of the event against their usual exposure. Cases from a case-control study can also be analysed by this method if appropriate information is obtained. METHODS: We apply the case-crossover method to data collected in a case-control study of acute coronary events, to estimate the risk of alcohol consumption in the 24 h before a coronary event. Two questions, concerning the usual frequency of consuming alcohol and how much was consumed, were used in the analysis. The sensitivity of effect estimates to the two questions and to different ways of eliciting probabilities from them, are examined. The cases and controls were both analysed in the same way, assigning controls a 'pseudo-event' time at random. It is suggested that controls may provide a benchmark to establish whether bias exists in the case-series analysis. RESULTS: We find that the case-crossover analysis is sensitive to how exposure probabilities are assigned. Adopting a Poisson model for exposures leads to inflated risk estimates. The bias is removed if the control series is used to adjust estimates. There appears to be a small protective effect from alcohol consumption. CONCLUSION: Case-crossover designs have considerable potential, but reliable information on usual exposure limits their applicability. More research is required on how best to elicit exposure probabilities.

Alcohol Drinking↗

PubMed1999

Occurrence of an HIV-1 gp160 endoproteolytic activity in low-density vesicles and evidence for a distinct density distribution from endogenously expressed furin and PC7/LPC convertases.

Human immunodeficiency virus (HIV) glycoprotein (gp) 160 processing by host cell proteinases is an essential step for viral fusion and infectivity. We have identified a rat liver subcellular fraction which specifically processes gp160 into gp120 and gp41. Using equilibration of microsomes in sucrose gradients, the gp160 cleavage activity was associated with particles equilibrating at low densities, well-separated from the endoplasmic reticulum, cis-Golgi network, Golgi stacks, lysosomes and plasma membrane. Its density distribution was compatible with light secretory vesicles derived from the trans-Golgi network (TGN) or to endosomes, but association with endosomes was not supported by free flow electrophoresis. Although furin and pro-protein convertase (PC) 7/LPC have been proposed as the major gp160 processing convertases, the rat liver microsomal gp160 processing activity was essentially resolved from furin and only partially overlapped PC7/LPC. These data suggest that proteinase(s) other than furin and PC7/LPC, presumably located in TGN-derived vesicles, may participate in the gp160 processing into gp120 and gp41.

Amino Acid Sequence↗

PubMed1998

Furin and proprotein convertase 7 (PC7)/lymphoma PC endogenously expressed in rat liver can be resolved into distinct post-Golgi compartments.

The intracellular compartmentalization in rat liver of the membrane-associated convertases furin and proprotein convertase 7 (PC7)/lymphoma PC (LPC) was investigated by analytical subcellular fractionation. In control animals, both enzymes were found to localize in fractions depleted of endoplasmic reticulum, cis-Golgi and lysosomal markers, but to co-distribute with the Golgi marker galactosyltransferase and the trans-Golgi network (TGN) marker TGN38. After overloading Golgi-derived vesicles with very-low-density lipoproteins (VLDL) by feeding rats with ethanol, the distribution of PC7/LPC was shifted markedly towards lower densities, in contrast with those of furin and the TGN marker. This provides support for the TGN localization of endogenously expressed furin and indicates that, at steady state, a considerable proportion of PC7/LPC may be associated with vesicles derived from the TGN.

Animals↗

PubMed1996

Identification of the paired basic convertases implicated in HIV gp160 processing based on in vitro assays and expression in CD4(+) cell lines.

The human immunodeficiency virus HIV envelope glycoprotein gp160 is synthesized as an inactive precursor, which is processed into its fusiogenic form gp120/gp41 by host cell proteinases during its intracellular trafficking. Kexin/subtilisin-related endoproteases have been proposed to be enzyme candidates for this maturation process. In the present study, 1) we examined the ability of partially purified precursor convertases and their isoforms to cleave gp160 in vitro. The data demonstrate that all the convertases tested specifically cleave the HIV envelope glycoprotein into gp120 and gp41. 2) We demonstrated that a 19-amino acid model peptide spanning the gp120/gp41 junction is cleaved by all convertases at the same gp160 site as that recognized in HIV-infected cells. 3) In an effort to evaluate specific convertase inhibitors, we showed that the alpha1-antitrypsin variant, alpha1-PDX, inhibits equally well the ability of the tested convertases to cleave gp160 in vitro. 4) Three lymphocyte cell lines were screened by reverse transcription polymerase chain reaction in an effort to identify which are the convertases expressed in the most common HIV target, the CD4(+) lymphocytes. The data demonstrate that furin, PC5/6, and the newly cloned PC7 are the main transcribed convertases, suggesting that these proteinases are the major gp160-converting enzymes in T4 lymphocytes.

Amino Acid Sequence↗

PubMed1996

Penetrating injuries of the iliac arteries: a South African experience.

BACKGROUND: We did a retrospective study of 62 patients with penetrating injuries of the iliac arteries. METHODS: The cause of injury was gunshot wound in 85.5% and stabbing in 14.5%. The arterial repair was achieved by various means: lateral arteriorrhaphy, end-to-end anastomosis, and polytetrafluoroethylene interposition grafts. RESULTS: There was a 42% mortality rate from exsanguination or secondary coagulopathy directly related to the arterial injury. Persistent shock, resuscitative thoracotomy, free intraperitoneal hemorrhage, and the number of vascular injuries were directly related to mortality. CONCLUSIONS: A high index of suspicion, aggressive resuscitation, and prompt surgery are necessary to improve the chances of surviving this ominous injury.

Anastomosis, Surgical↗