Neuronal vacuole formation in the rat posterior cingulate/retrosplenial cortex after treatment with the N-methyl-d-aspartate (NMDA) antagonist MK-801 (dizocilpine maleate)

Cytoplasmic vacuoles appear in neurons of the posterior cingulate/retrosplenial cortex (PC/RS) of rats after treatment with N-methyl-d-aspartate (NMDA) receptor antagonists. Prominent dilatation of mitochondria and endoplasmic reticulum has been described within 2 h; however, the ultrastructural features of vacuole formation are unknown. To investigate this, the present study examined the PC/RS cortex of male rats (age 60–70 days) at 15, 30, 45, 60, 90, and 120 min after subcutaneous treatment with 1 mg/kg of the noncompetitive NMDA antagonist MK-801 (dizocilpine maleate, 5-methyl-10, 11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine). Subtle mitochondrial dilatation was identified in a few neurons as early as 15 min postdose (MPD). By 30 MPD, dilatation was more pronounced in mitochondria and also involved the endoplasmic reticulum and perinuclear space. Ribosomal disaggregation and degranulation were also evident by 30 MPD. At all subsequent time points, dilatation of mitochondria and endoplasmic reticulum progressed in severity. Although the relative involvement of mitochondria and endoplasmic reticulum varied, glia were not involved. These ultrastructural data suggest that after treatment with MK-801, mitochondrial dilatation precedes involvement of endoplasmic reticulum in vacuolization of susceptible PC/RS cortical neurons. The early mitochondrial effects identified in this study suggest an initial metabolic insult that rapidly progresses to affect endoplasmic reticulum and ribosomes. This strengthens the relationship between the ability of certain NMDA antagonists to induce energy perturbations and neuronal vacuoles in the same region of the rat cerebral cortex.     

Matrix vesicles are enriched in metalloproteinases that degrade proteoglycans

Summary This study examined the presence of extracellular matrix processing enzymes in matrix vesicles produced by rat costochondral resting zone and growth zone chondrocytes in culture. Optimum procedures for the extraction of each enzyme activity were determined. Enzyme activity associated with chondrocyte plasma membrane microsomes was used for comparison. There was a differential distribution of the enzyme activities related to the cartilage zone from which the cells were isolated. Acid and neutral metalloproteinase (TIMP), plasminogen activator, and betaglucuronidase were highest in the growth zone chondrocyte (GC) membrane fractions when compared with matrix vesicles and plasma membranes isolated from resting zone chondrocyte (RC) cultures. There was a threefold enrichment of total and active acid metalloproteinase in GC matrix vesicles, whereas no enrichment in enzyme activity was observed in RC matrix vesicles. Total and active neutral metalloproteinase were similarly enriched twofold in GC matrix vesicles. TIMP, plasminogen activator, and betaglucuronidase activities were highest in the plasma membranes of both cell types. No collagenase, lysozyme, or hyaluronidase activity was found in any of the membrane fractions. The data indicate that matrix vesicles are selectively enriched in enzymes which degrade proteoglycans. The highest concentrations of these enzymes are found in matrix vesicles produced by growth zone chondrocytes, suggesting that this may be a mechanism by which the more differentiated cell modulates the matrix for calcification.     

Probe™, a balloon wire: Initial experience

Coronary angioplasty is unsuccessful in <3–5% of cases because the balloon catheter fails to follow a guidewire that has traversed a lesion. Between June 1986 and August 1987, 31 lesions were unable to be crossed with at least two standard angioplasty catheters. Finally, a 2.0-mm-diameter Hartzler LPS (ACS) was utilized and successfully crossed and dilated 16 out of 31 lesions (52%). In the remaining 15 lesions, the Probe^TM (USCI) 2.0 mm diameter × 1.5 cm long balloon wire was able to cross the lesions in 13 (82%) and successfully dilated 12. In one case, lesion rigidity prevented the balloon from expanding at 14 atm. A right coronary artery lesion was attempted in 11 cases, and a left anterior descending and circumflex artery lesion in two patients each. No complications were encountered. In seven out of 12 successful Probe^TM cases, a larger balloon catheter was used to further dilate the artery. This new balloon wire has increased our success rate in severe stenoses and in tortuous vessels with severe distal lesions, in which presently available angioplasty equipment has failed.     

Effects of a long-distance run on cardiac markers in healthy athletes.

BACKGROUND: Running a marathon is a stressful event for athletes. Limited research exists on the role of cardiac markers during such a strenuous event. The aim of this study was to investigate detailed changes in cardiac markers before and after a long-distance run. METHODS: We studied 25 male and 2 female runners (age 34-64 years) who were running the Visé-Maastricht-Visé marathon. Blood samples were drawn just before and immediately after finishing the marathon. An additional blood sample was collected 24 h later. RESULTS: Running the marathon led to a significant increase in cortisol. This returned to baseline values 24 h after the marathon. There was a slight increase in brain natriuretic peptide (BNP); however, this was not statistically significant. On the contrary, the N-terminal fragment of BNP (NT-pro-BNP) was significantly increased immediately after the run and was normalized 24 h later in 26 out of 27 runners (96%). The magnitude of the transient elevations in BNP and NT-pro-BNP increased with the age of the athletes. Furthermore, in 9 out of 27 runners there was a significant increase in troponin T. However, in all these runners this increase was transient and troponin-T levels returned to baseline values 24 h after the marathon. CONCLUSIONS: Running a marathon significantly increases NT-pro-BNP levels in healthy adults. This increase could be partially attributed to cardiac stress. The transient increases in BNP, NT-pro-BNP and troponin T are more likely to reflect myocardial stunning than cardiomyocyte damage. It seems that the magnitude of the increase in BNP could serve as a marker of the biological age of the myocardium.     

Antineutrophil cytoplasmic antibodies (ANCA) in idiopathic pulmonary hemosiderosis

Four children were diagnosed with idiopathic pulmonary hemosiderosis (IPH), over a period of 4 years. Retrospectively, antineutrophil cytoplasmic antibodies (ANCA) were studied by indirect immunofluorescence (IIF) and ELISA in 18 sera from these patients, stored at -20°C. ANCA-positive sera, from 1/20 to 1/1, 200 dilution, were found in 3/4 of the patients, by IIF. The patient with the highest titre of ANCA died 3 months later during an acute crisis, the other two patients need a minimal dose of steroids. In one case only, a patient who is still without treatment, had no ANCA. The antibodies anti-myeloperoxidase and anti-pro-teinase-3 were negative or at border line levels. Rheumatoid factor, anti-nuclear (Hep-2), anti-endomysial, anti-reticulin and antibasement membrane antibodies were negative in all sera. The surviving patients were followed-up for more than 10 years with no systemic or renal disease appearences. The presence of serum ANCA may help to classify children with pulmonary haemorrhage and may have a prognostic value.     

The incidence of complications associated with retrobulbar injection of anaesthetic for ophthalmic surgery.

A retrospective study of the incidence of complications associated with the use of retrobulbar injections was carried out on a sample of 1083 consecutive patients. The overall incidence of retrobulbar haemorrhage (1.3%) compared favourably with previous reports, but was found to be related to the experience of the surgeon. None of the more serious ocular complications of retrobulbar injection occurred in this sample. The relative safety of this technique is discussed.     

Cerebral lateralization and color perception: a transcranial Doppler study.

Eight normal subjects were examined in dark, light and color conditions. Mean cerebral blood flow velocity (MBFV) were recorded almost simultaneously from their posterior cerebral arteries (PCA) using transcranial Doppler (TCD) ultrasound. The side-to-side difference was significant during the dark (p = 0.0159) and color stimulation (p = 0.0001) but not in light condition. This side-to-side difference in MBFV was used to characterize lateralization of color perception. This showed that the right PCA was always greater than the left during the presentation of color stimuli. Primary psychological colors (blue, yellow, red and green) induced greater lateralization as compared with color resulting from a mixed blue-green wavelength. This suggests that the right visual cortex is selectively sensitive to wavelengths.     

FIA—fluorimetric determination of thiamine

A flow injection-fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1–4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.