Astroglial alterations in rat hippocampus during chronic lead exposure.

The present study was performed in order to follow the response of astroglial cells in the rat hippocampus to chronic low-level lead exposure. The experiments combined immunohistochemistry using anti-glial fibrillary acidic protein (GFAP) antibody and conventional transmission electron microscopy (EM). Chronic administration with drinking water [1 g% w/v (subclinical dose) of lead acetate dissolved in distilled water] was started through the mother's milk when pups were 7 days old. Following weaning, experimental offspring were treated for 3 months with the same concentration of adulterated water. The group of intoxicated animals and their controls were sacrificed by perfusion-fixation at 30, 60, and 90 days of exposure. After 60 days of lead treatment, staining of GFAP-positive cells demonstrated an astroglial transformation from the quiescent to the reactive state, characterized by an increase in GFAP. In control rats no changes in GFAP immunostaining were observed. The intensity of the astroglial response was enhanced after 90 days of lead intoxication, showing an increment of GFAP immunoreactivity. Quantification of these changes was made by computerized image analysis, confirming that the sectional areas of the astroglia in lead-exposed animals were larger than those in controls. These results are consistent with the ultrastructural alterations. Simultaneously with the increment in gliofilaments, intranuclear inclusions were seen in some astrocytes. The mechanisms by which lead affects astrocytes are unknown. Probably the astroglial changes induced by lead intoxication produce microenvironmental modifications that may disturb the neuronal function.     

Neuronal development of the chick cerebral cortex. A Golgi study

The neuronal morphological development of the avian telencephalic cortex (DMC) is studied in Golgi-stained brain sections. The neuronal types at embryonic days 10, 13, 16, as well as of newborn chick are identified. The immature neurons are characterized by the presence of hair-like processes, growth cones and dendritic varicosities. These characteristics are absent in neuronal types of newborn chick. There are five patterns of differentiation, which produce six neuronal types in the newborn chick: horizontal neurons, pyramidal neurons, bipyramidal neurons, short axon multipolar neurons, long axon multipolar neurons and periventricular neurons. The morphological features of migrating embryonic cells are described. The dendritic spines appear in 16-day embryos in the majority of neuronal types.     

Human dignity in the Nazi era: implications for contemporary bioethics

Background  

The justification for Nazi programs involving involuntary euthanasia, forced sterilisation, eugenics and human experimentation were strongly influenced by views about human dignity. The historical development of these views should be examined today because discussions of human worth and value are integral to medical ethics and bioethics. We should learn lessons from how human dignity came to be so distorted to avoid repetition of similar distortions.     

Sensitization to Zygophyllum fabago pollen. A clinical and immunologic study

Zygophyllum fahago is a herbaceous plant found widely in the Mediterranean area. There are no previous reports of its allergenicity. An aerobiologic and clinical survey was conducted in Murcia, southern Spain, to determine the quantity of airborne pollen and establish the possible role of this pollen as a cause of allergic symptoms. With a Hirst volumetric trap, we determined the atmospheric concentrations of this pollen in 1993, 1994,1995, and 1996. Of 1180 patients tested, 181 (15,34%) had a positive skin test. To determine its allergenicity, we divided 47 patients into three groups: in group 1, all the patients had symptoms of rhinoconjunctivitis plus asthma; in groups 2 and 3, rhinoconjunctivitis. In group 1, we performed a bronchial provocation test (BPT): in groups 2 and 3, we performed nasal provocation (NPT) and conjunctival provocation (CPT) tests, respectively, SDS-PAGE was used to characterize the antigenic fractions and RAST inhibition to determine cross-reactivity with other pollens. The pollen dispersion period is from May to September (445 grains/m³), BPT was positive in 13 of 15 patients, NPT in 14 of 16 patients, and CPT in 13 of 16 patients. RAST inhibition revealed cross-reactivity with Mercurialis, Ricinus, Olea. and Betula. SDS-PAGE identified 25 IgE antibody-binding components, five of which (60, 65, 41, 38, and 15.5/14,7 kDa) were recognized by 40% of the sera. By SDS-PAGE immunoblotting with sunflower antiprofilin rabbit serum and affinity chromatography we established that the Z. fahago extract has profilin. This study shows that this pollen becomes airborne and elicits an IgE response which triggers respiratory symptoms in allergic subjects.     

Aminotriazole effects on lung and heart H2O2 detoxifying enzymes and TBA-RS at two pO2

In order to clarify the physiological role in vivo of H2O2-detoxifying enzymes at low and high levels of O2 tension we studied catalase (CAT), glutathione peroxidases (GP), and in vivo peroxidation (TBA-RS) in the lung and heart of Rana perezi frogs chronically treated with hyperoxia, aminotriazole (AT) -a CAT inhibitor-, or both. Hyperoxia did not change CAT, GP or TBA-RS. Aminotriazole caused an almost complete depletion of CAT, a 30% decrease of GP and a 132% (lung) to 200% (heart) increase of TBA-RS. Changes similar to these were found in the group treated with AT in hyperoxia. No mortality or changes in total or organ weight occurred in the experimental groups. Main conclusions are: (1) The maximal hyperoxia tolerance showed by frogs among vertebrates does not need antioxidant enzyme induction from lung or heart and is probably related to the presence of high constitutive levels of GP in relation to metabolic rate. (2) Even in normoxia the tissues present significant amounts of H2O2, and CAT is needed to avoid oxidative damage. GP does not compensate its absence. The implications of these results in relation to oxygen toxicity in man is discussed.     

Inhibitory effects of amitriptyline on the stimulation-induced Ca2+ increase in parotid acini

The present study demonstrates the effects of the antidepressant, amitriptyline, and the acetylcholine antagonist, atropine, on the stimulation-induced rise in cytosolic, free Ca2+ (Cai2+). The changes in Cai2+ of collagenase-isolated rat parotid acini were measured by means of the Ca2(+)-sensitive dye, fura-2. It was found that stimulation by carbachol resulted in a maximal increase of 582 +/- 34 nM (mean +/- S.E.) in Cai2+ with a ks of 5.8 +/- 1.3 microM. Adrenaline caused a rise of 380 +/- 22 nM in Cai2+ with a ks of 0.5 +/- 0.2 microM. Amitriptyline and atropine were found to inhibit the carbachol-induced rise in Cai2+ with dissociation constants (kI) of 105 and 1.25 nM, respectively, in the absence of agonist. The adrenergic-induced rise in Cai2+ was inhibited by amitriptyline with a kI of 45 nM. Amitriptyline was found to inhibit both receptor classes by a competitive or mixed type of inhibition. Similarly, atropine exerted the same type of inhibition on the acetylcholine receptor. Amitriptyline and atropine were found to be mutually exclusive for competing for substrate binding on the receptor. These findings are consistent with a common binding site for amitriptyline and atropine on the acetylcholine receptor, possibly in close proximity with, but different from the substrate binding site. The stimulation-induced cell shrinkage evoked by the loss of electrolytes and water from the acini was measured by a 90 degree light scattering signal. It was found that this method makes possible the detection of autonomic side-effects of antidepressants on acini suspended in protein-containing media.     

Metabolic response to beet fibre test meals

Test meals with 10.9 g dietary fibre from sugar beet and corresponding control meals were given to eight healthy subjects, aged 67 ± 9 years. The postprandial glucose, triglyceride, hormone and glycerol responses were monitored during 3 hours. After the beet fibre meal the insulin and C-peptide areas were reduced by 28 ( P < 0.01) and 22% ( P > 0.025), respectively, and the somatostatin levels increased by approximately 30% ( P > 0.05). Further, the maximum relative postprandial reduction of plasma glycerol levels was less evident after the fibre-rich meal than after the control meal (36 ± 4% v. 46 ± 4%, P < 0.05). There was no apparent difference in the overall glycaemic response between the meals. The triglyceride levels were similar after both test meals.
Suspension of beet fibre bread given to rats by oro-gastric intubation induced lower blood glucose response than a control bread at 15 and 30 min ( P < 0.001), respectively, but a similar insulin response.
The results suggest an effect of beet fibre on the rate of carbohydrate absorption, expressed as a lower insulin response in the healthy volunteers and a reduced glucose response in the rat.
The mechanism behind this effect in healthy subjects could possibly be mediated by an increased somatostatin response.