Luc Wouters

Structural Correlates of Regional Myocardial Dysfunction in Patients With Critical Coronary-artery Stenosis - Chronic Hibernation

The morphologic changes in the myocardium of hypocontractile segments, especially the possible structural counterparts underlying chronic ischemia, are not well documented. Light and electron microscopy was performed on myocardium derived from the anterior wall of the left ventricle of 98 patients during coronary artery bypass grafting. Wall motion data were collected from the region corresponding to the biopsied zone. The changes seen in a substantial part of the cardiomyocytes corresponded to dedifferentiation rather than degeneration characteristics. The affected cardiomyocytes showed a partial to complete loss of sarcomeres, sarcoplasmic reticulum, and T-tubules and presented abundant plaques of glycogen, strands of rough endoplasmic reticulum, lots of minimitochondria, and a tortuous nucleus. The volume of the cells was similar to that of normal cells. The number of the affected cells was consistently higher in endocardial parts than in epicardial ones. The cell changes occurred in the myocardium of patients both with and without a previous Q-wave infarction. There was a significant relation between anterior wall motion abnormalities and the incidence of affected cells in the endocardium, but not in the epicardium. A significant relationship was found in noninfarcted patients between the presence of affected cells and the amount of connective tissue. Furthermore, in these patients the number of affected cells depended on the degree of stenosis. It is proposed that segments in which these structural changes prevail will not recover immediately after revascularization but that they might show a delayed recovery of function, because structural remodeling requires time in order to regain sufficient contractile material.

Impaired autoregulation of cerebral blood flow in an experimental model of traumatic brain injury.

In order to study the pathophysiology and the intracranial hemodynamics of traumatic brain injury, we have developed a modified closed-head injury model of impact-acceleration that expresses several features of severe head injury in humans, including acute and long-lasting intracranial hypertension, diffuse axonal injury, neuronal necrosis, bleeding, and edema. In view of the clinical relevance of impaired autoregulation of cerebral blood flow after traumatic brain injury, and aiming at further characterization of the model, we investigated the autoregulation efficiency 24 h after experimental closed-head injury. Cortical blood flow was continuously monitored with a laser-Doppler flowmeter, and the mean arterial blood pressure was progressively decreased by controlled hemorrhage. Relative laser-Doppler flow was plotted against the corresponding mean arterial blood pressure, and a two-line segmented model was applied to determine the break point and slopes of the autoregulation curves. The slope of the curve at the right hand of the break point was significantly increased in the closed head injury group (0.751 +/- 0.966%/mm Hg versus -0.104 +/- 0.425%/mm Hg,p = 0.028). The break point tended towards higher values in the closed head injury group (62.2 +/- 20.8 mm Hg versus 46.9 +/- 12.7 mm Hg; mean +/- SD, p = 0.198). It is concluded that cerebral autoregulation in this modified closed head injury model is impaired 24 h after traumatic brain injury. This finding, in addition to other characteristic features of severe head injury established earlier in this model, significantly contributes to its clinical relevance.

Protection With Lubeluzole Against Delayed Ischemic Brain Damage in Rats: A Quantitative Histopathologic Study

BACKGROUND AND PURPOSEnCerebral ischemia may lead to glutamate-induced excitotoxic damage in vulnerable brain areas. Lubeluzole is not an N-methyl-D-aspartate antagonist but prevents postischemic increase in extracellular glutamate concentrations. The present study examined whether lubeluzole, administered after global incomplete ischemia in rats, is capable of preserving the structural integrity of CA1 hippocampus.nnnMETHODSnIschemia was induced by bilateral carotid artery occlusion and severe hypotension for a duration of 9 minutes. Delayed neuronal cell death was histologically evaluated 7 days later. This was done by scoring acidophilic cell change and coagulative necrosis and by counting the number of surviving neurons in the CA1 subfield. Experiments were performed according to a paired design (13 animals per treatment group).nnnRESULTSnPosttreatment with lubeluzole (0.31 mg/kg i.v. bolus at 5 minutes and 0.31 mg/kg i.v. infusion during 1 hour) resulted in significant neuroprotection. Whereas in the untreated rats there were 42 (median) viable neurons per millimeter CA1 layer in the left and 69 in the right hemisphere, in the drug-treated rats 99 viable neurons per millimeter were found in the left (P = .002) and 113 in the right hemisphere (P = .013). Histological scores, reflecting altered staining properties of the hippocampal cells, correlated strongly with the quantitative data, reflecting the structural integrity of CA1 pyramidal neurons.nnnCONCLUSIONSnLubeluzole, when administered after an ischemic insult in rats, protects vulnerable brain regions against delayed structural injury. The results support the potential clinical use of this new drug in stroke treatment.

The l-enantiomer of nebivolol potentiates the blood pressure lowering effect of the d-enantiomer

In this study the effect of l-nebivolol on the blood pressure lowering action of d-nebivolol was investigated after intraperitoneal administration of the drugs to spontaneously hypertensive rats. Doses of l-nebivolol which did not affect blood pressure when given alone potentiated the decrease in systolic and diastolic blood pressure induced by 1.25 mg.kg-1 d-nebivolol. The potentiating effect of l-nebivolol was seen at doses higher than 0.16 mg.kg-1. At 1.25 mg.kg-1 d-nebivolol significantly reduced the heart rate, an effect which was not potentiated by l-nebivolol in doses up to 1.25 mg.kg-1. Higher doses of l-nebivolol (2.5 and 5.0 mg.kg-1) in combination with 1.25 mg.kg-1 d-nebivolol not only lowered the blood pressure further, but also significantly reduced the heart rate; thus at these doses the enantiomers together exerted more pronounced beta 1-adrenoceptor blocking properties. This is probably disadvantageous, because d,l-nebivolol has been shown to decrease arterial blood pressure in hypertensive patients and animals before it reaches its maximal beta 1-adrenoceptor blocking effect. Therefore, the racemic mixture of 50% d-nebivolol and 50% l-nebivolol seems to contain the two compounds in near optimal proportions for an antihypertensive effect.

Antitumoral Effects of Liarozole in Androgen-Dependent and Independent R3327-Dunning Prostate Adenocarcinomas

We examined the in vivo antitumoral effects of liarozole against androgen-dependent and independent Dunning rat prostatic tumors. Liarozole, applied as a dietary admixture, at a dose of 120 mg./100 gm. food, equivalent to 100 mg./kg. per day, inhibited the growth of the slow growing, well-differentiated, androgen-dependent Dunning-H tumor (median tumor volume decrease of 60%). At the same dose it also significantly reduced the growth of the androgen-independent, moderately differentiated PIF-1 (-60%) and androgen-independent, anaplastic AT-6 tumors (-73%). The growth of AT-6 sq tumor showing squamous metaplasia was unaffected by liarozole. When administered by oral gavage, liarozole at 40 (-82%) mg./kg. twice a day was as effective as castration (-92%) in reducing the androgen-dependent, poorly differentiated Dunning R3327-G tumor. Liarozole, administered by gavage, twice a day, also significantly reduced median tumor volume in the androgen-independent, AT-6 sq (-90% at 60 mg./kg., twice a day). This difference between liarozole administration by gavage and food admixture will have to be taken into account in further experimental studies. Inhibition of the growth of several androgen-dependent and, chiefly, androgen-independent Dunning prostate carcinoma sublines that differ widely in their histological degree of differentiation and growth rate suggests that liarozole may be a suitable agent for evaluation in second line treatment of hormone refractory prostate carcinoma in patients who relapse after androgen ablation.

Effects of liquid preloads with different fructose/fibre concentrations on subsequent food intake and ratings of hunger in women

Preloads (250 ml) of 2% or 10% fructose containing 1% soluble fibre and 1% insoluble fibre or 10% fructose with 3% soluble fibre and 1% insoluble were administered 60 min before lunch to 24 healthy women, who were slightly overweight and considerably weight concerned. The fibre consisted of guar gum, partly hydrolysed for the soluble form. The placebo consisted of a solution of sweeteners (cyclamate and saccharin). After the experiment with three preload-types and a placebo, a random subset of 15 subjects returned for an experiment with one preload-type and a placebo, given 30 or 60 min before lunch. Food intake during the subsequent lunch was only significantly different from after the placebo in this subset of 15 subjects after the 10% fructose/3% soluble and 1% insoluble fibre preload after intervals of 30 or 60 min. However, energy intake of preload and meal was significantly higher than energy intake of placebo and meal. At the 30-min delay, eating rate was significantly lower after the preload than after the placebo; also, hunger ratings were lower after intake of a preload and meal than after intake of the placebo+meal, from immediately after lunch until 5 hours later. Energy intake over 24 h was not affected by administration of fructose/fibre or placebo 30 or 60 minutes before lunch in the 24 women.

Activity of the Triazole Antifungal R126638 as Assessed by Corneofungimetry

Background: R126638 is a novel triazole exhibiting potent in vitro and in vivo antifungal activity against fungal pathogens including dermatophytes and yeasts. Objective: To determine the antifungal activity in time in the stratum corneum of healthy volunteers after oral intake of R126638 at a daily dose of 100 or 200 mg for 1 week. Method: Sixteen male volunteers were randomly allocated to oral treatment with either 100 or 200 mg of R126638 once daily for 1 week. Five cyanoacrylate skin surface strippings (CSSS) were obtained from the forearm of each subject before drug intake at day 1. CSSS were also collected during treatment at day 2 (24 h after the first drug intake, before the second drug intake), at day 4 (before the fourth drug intake) and at day 7 (10 h after the last drug intake). The post-treatment lingering effect was assessed at day 10 (3 days after treatment) and at day 14 (7 days after treatment). The corneofungimetry bioassay was performed on these CSSS to assess the antifungal profile of R126638. Cells of different fungal species (Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum canis, Candida albicans and Malassezia globosa) were deposited and cultured for 10 days on CSSS in a sterile and controlled environment. The extent of fungal growth on the stratum corneum was determined using computerized image analysis. Results: R126638 clearly reduced the growth of all tested fungal species. The onset of effects of R126638 was evidenced at day 4 when it reached statistical significance for 3 of 5 species. At day 7, significance was reached for 4 of 5 species. During the posttreatment period, R126638 remained effective for 4 of 5 species at day 10, and this activity persisted until day 14 for 2 of 5 species. Conclusion: A broad spectrum antifungal activity was rapidly expressed in the stratum corneum after oral intake of R126638. The drug likely reached the upper layers of the stratum corneum by diffusion and persisted in this location for at least 7 days after treatment.

Enhanced platelet turnover and prostaglandin production in spontaneously hypertensive rats

The anti-hypertensive effect of ketanserin, a selective 5-HT2 antagonist, both in experimental and human pathology (1,2) could implicate the blood platelets as a source for peripherally available 5-hydroxytryptamine (5-HT), acting to increase peripheral vascular resistance (3). Therefore we examined various blood platelet parameters in spontaneously hypertensive rats in comparison with normotensive Wistar rats.

Expression of retinoid-regulated genes in lamellar ichthyosis vs. healthy control epidermis: changes after oral treatment with liarozole.

Lamellar ichthyosis is a keratinization disorder caused by TGM1, Ichthyin and several other gene mutations. A new treatment option is liarozole, which blocks the cytochrome P450 (CYP26)-mediated catabolism of endogenous all-trans retinoic acid. This study focuses on the expression of retinoid-related genes in ichthyotic epidermis before and after treatment with oral liarozole. We first compared the mRNA expression of cellular retinoic acid binding protein II (CRABPII), keratin (KRT) 2 and 4, CYP26A1 and B1, and two markers of inflammation (interleukin-1alpha and tumours necrosis factor (TNF)-alpha) in shave biopsies from 11 genetically defined, untreated patients and 12 age- and sex-matched healthy controls, finding no overt differences between the groups, besides elevated CRABPII expression. We then studied the biomarkers before and after 4 weeks of treatment with liarozole (75 or 150 mg/day), which produced a better therapeutic response in patients with Ichthyin (n=3) than in those with TGM1 (n=6) mutations. A significant decrease in the mRNA expression of KRT2 and TNF-alpha, and trends toward increased expression of KRT4 and CYP26A1 were observed in liarozole-treated patients, consistent with an increased retinoid stimulation of epidermis. However, there were no dose-related responses and the results of the immunostaining did not always parallel the mRNA findings. The results suggest that liarozole exerts a therapeutic effect in lamellar ichthyosis by mildly affecting the expression of retinoid- regulated genes in epidermis.

A Pilot Study on Seborrheic Dermatitis Using Pramiconazole as a Potent Oral Anti-Malassezia Agent

Background: Seborrheic dermatitis is considered to be a Malassezia-driven disease. Little objective information is available so far from biometrological quantitative assessments of this skin condition. Pramiconazole is a novel triazole with potent in vitro antifungal activity, especially against Malassezia spp. Objective: To study the sequential effects of pramiconazole on Malassezia, inflammation and epidermal changes. Method:This study was performed in 2 groups of subjects suffering from seborrheic dermatitis. The first group (n = 17) remained untreated and was used as control. Clinical, mycological and biometrological assessments were performed at inclusion and during the following 2 weeks. The second group of subjects (n = 10) received a single 200-mg oral dose of pramiconazole at inclusion. Clinical, mycological and biometrological evaluations were performed before and during 1 month following the single antifungal intake. For both parts of the study, several parameters were assessed including yeast density, desquamation, erythema, itching and sebum excretion. Results: In the control group, no significant changes were observed in any of the parameters during the observation period. The findings were markedly different in the pramiconazole-treated subjects. The yeast density was significantly improved on days 3, 7 and 28. Desquamation, erythema, itching, and the global clinical evaluation as assessed by the patients and investigators became significantly improved on days 7 and 28. A trend in decrease of scaliness was noted. No effect on sebum excretion was evidenced. In conclusion, a single 200-mg dose of pramiconazole exhibitsin vivo efficacy in controlling some important clinical aspects of seborrheic dermatitis. Following a reduction in the number of yeasts on day 3, a decrease in the severity of clinical signs and symptoms occurred from day 7 onwards. Sebum excretion appeared uninvolved in the clearing process of seborrheic dermatitis. Conclusion: A single 200-mg dose of pramiconazole appears to abate seborrheic dermatitis. The density in Malassezia present on lesional skin is first decreased, followed by clearing of the clinical signs.