Assessment of ozone variations and meteorological effects in an urban area in the Mediterranean Coast

Ozone concentrations are valuable indicators of possible health and environmental impacts. However, they are also used to monitor changes and trends in the sources of both ozone and its precursors. For this purpose, the influence of meteorological variables is a confusing factor. This study presents an analysis of a year of ozone concentrations measured in a coastal Spanish city. Firstly, the aim of this study was to perceive the daily, monthly and seasonal variation patterns of ozone concentrations. Diurnal cycles are presented by season and the fit of the data to a normal distribution is tested. In order to assess ozone behaviour under temperate weather conditions, local meteorological variables (wind direction and speed, temperature, relative humidity, pressure and rainfall) were monitored together with ozone concentrations. The main relationships we could observe in these analyses were then used to obtain a regression equation linking diurnal ozone concentrations in summer with meteorological parameters.

Characterization of GFAP expression and cell proliferation in the rat median eminence following hypophysectomy

To analyze whether the reorganization of the rat median eminence after hypophysectomy might be related to changes in glial fibrillary acidic protein (GFAP)- and cellular proliferation, the distribution of cells immunoreactive for GFAP and the proliferation rate of such cells were analyzed at 20, 40 and 60 days posthypophysectomy. For this study, four rostro-caudal regions of the median eminence were differentiated: the retrochiasmatic, preinfundibular, infundibular and postinfundibular regions. In each of these regions, three layers were studied: the ependymal, the internal and the external. At 20 and 40 days after hypophysectomy, significant increases in cellular proliferation affecting all three layers studied in the preinfundibular and infundibular regions were found. At the same time points, increases in GFAP expression were also observed. However, after 60 days, GFAP and proliferative cellular nuclear antigen (PCNA) expression decreased. Although variations of PCNA and GFAP levels were evident, no colocalisation of PCNA and GFAP was found in the cells of the median eminence in untreated or hypophysectomized rats when sections were analyzed by double immunohistochemical staining. Our results suggest that reorganization of median eminence involves alterations (or modulation) of GFAP-immunoreactive cells together with a proliferation of cells that are not GFAP-immunoreactive. This study also demonstrates that this reorganization is completed within the first two months after hypophysectomy.

Bisoprolol and nifedipine SR in the treatment of hypertension in the elderly

Forty outpatients (11 men and 29 women) aged between 65 and 85 years (mean age of 68 years) with mild to moderate hypertension [mean systolic/diastolic blood pressure (SBP/DBP) after 2 weeks on placebo of 175/102 mm Hg] were included in a randomized, double-blind, parallel-group study to compare the efficacy and tolerance of 10 mg of bisoprolol once daily (o.d., n = 20) and 20 mg of nifedipine sustained release (SR) b.i.d. (n = 20) during 4 weeks of treatment. SBP and DBP were significantly reduced compared to baseline with both treatments. There was no significant difference in efficacy between the two treatments after 2 and 4 weeks. After 2 weeks, the number of patients with normalized DBP (< or =90 mm Hg) was higher with bisoprolol than with nifedipine, this difference no longer being present after 4 weeks. Resting heart rate was significantly reduced with bisoprolol from 78+/-8 to 68+/-9 beats/min after 4 weeks, but there was no change in heart rate with nifedipine. Adverse events were reported by 6 patients on bisoprolol (20 events) and 12 patients on nifedipine (51 events) and the overall tolerance of bisoprolol was considered to be significantly better than that of nifedipine. Because bisoprolol is equally effective when administered once daily in comparison with nifedipine SR, which has to be given twice daily, and since bisoprolol exhibits a better tolerance, this beta-blocker appears to be a useful drug of first choice for the treatment of elderly hypertensive patients.

Bisoprolol vs. chlorthalidone: a randomized, double-blind, comparative study in arterial hypertension

The antihypertensive effect and tolerance of bisoprolol and chlorthalidone were evaluated in a randomized, double-blind, controlled trial during 4 weeks of treatment. A total of46 patients, aged 18-65 years, were initially included; 41 patients presenting with a diastolic blood pressure between 95 and 120 mm Hg at the end of a previous placebo period completed the trial. They were randomly allocated to two groups: 22 patients were treated with bisoprolol 10 mg o.d., and 19 patients with chlorthalidone 50 mg o.d. Both treatments induced a significant reduction in systolic and diastolic blood pressure (p < 0.001). No difference in antihypertensive efficacy was found between the two treatments after 4 weeks. However, with chlorthalidone, significant changes were found with regard to serum potassium (decrease; p < 0.001) and uric acid (increase: p < 0.05) and the incidence of clinical side effects was higher in the chlorthalidone group (37%) in comparison to the patients treated with bisoprolol (13%).

Glutamine potentiates TNF-alpha-induced tumor cytotoxicity

L-glutamine (Gln) sensitizes tumor cells to tumor necrosis factor (TNF)-alpha-induced cytotoxicity. The type and mechanism of cell death induced by TNF-alpha was studied in Ehrlich ascites tumor (EAT)-bearing mice fed a Gln-enriched diet (GED; where 30% of the total dietary nitrogen was from Gln). A high rate of Gln oxidation promotes a selective depletion of mitochondrial glutathione (mtGSH) content to approximately 58% of the level found in tumor mitochondria of mice fed a nutritionally complete elemental diet (standard diet, SD). The mechanism of mtGSH depletion involves a glutamate-induced inhibition of GSH transport from the cytosol into mitochondria. The increase in reactive oxygen intermediates (ROIs) production induced by TNF-alpha further depletes mtGSH to approximately 35% of control values, which associates with a decrease in the mitochondrial transmembrane potential (MMP), and elicits mitochondrial membrane permeabilization and release of cytochrome c. Mitochondrial membrane permeabilization was also found in intact tumor cells cultured with a Gln-enriched medium under conditions of buthionine sulfoximine (BSO)-induced selective GSH synthesis inhibition. Enforced expression of the bcl-2 gene in tumor cells could not avoid the glutamine- and TNF-alpha-induced cell death under conditions of mtGSH depletion. However, addition of GSH ester, which delivers free intracellular GSH and increases mtGSH levels, preserved cell viability. These findings show that glutamine oxidation and TNF-alpha, by causing a change in the glutathione redox status within tumor mitochondria, activates the molecular mechanism of apoptotic cell death.

Tumoricidal activity of endothelial cells. Inhibition of endothelial nitric oxide production abrogates tumor cytotoxicity induced by hepatic sinusoidal endothelium in response to B16 melanoma adhesion in vitro

The mechanism of NO- and H(2)O(2)-induced tumor cytotoxicity was examined during B16 melanoma (B16M) adhesion to the hepatic sinusoidal endothelium (HSE) in vitro. We used endothelial nitric-oxide synthetase gene disruption and N(G)-nitro-l-arginine methyl ester-induced inhibition of nitric-oxide synthetase activity to study the effect of HSE-derived NO on B16M cell viability. Extracellular H(2)O(2) was removed by exogenous catalase. H(2)O(2) was not cytotoxic in the absence of NO. However, NO-induced tumor cytotoxicity was increased by H(2)O(2) due to the formation of potent oxidants, likely ( small middle dot)OH and (-)OONO radicals, via a trace metal-dependent process. B16M cells cultured to low density (LD cells), with high GSH content, were more resistant to NO and H(2)O(2) than B16M cells cultured to high density (HD cells; with approximately 25% of the GSH content found in LD cells). Resistance of LD cells decreased using buthionine sulfoximine, a specific GSH synthesis inhibitor, whereas resistance increased in HD cells using GSH ester, which delivers free intracellular GSH. Because NO and H(2)O(2) were particularly cytotoxic in HD cells, we investigated the enzyme activities that degrade H(2)O(2). NO and H(2)O(2) caused an approximately 75% (LD cells) and a 60% (HD cells) decrease in catalase activity without affecting the GSH peroxidase/GSH reductase system. Therefore, B16M resistance to the HSE-induced cytotoxicity appears highly dependent on GSH and GSH peroxidase, which are both required to eliminate H(2)O(2). In agreement with this fact, ebselen, a GSH peroxidase mimic, abrogated the increase in NO toxicity induced by H(2)O(2).

Possible mechanisms for tumour cell sensitivity to TNF-alpha and potential therapeutic applications

TNF is a macrophage/monocyte-derived cytokine with cytostatic and cytotoxic anti-tumour activity. TNF-alpha can cause haemorrhagic necrosis and regression of experimental tumours. Nevertheless, the TNF-alpha doses required to cure tumour-bearing mice lead to injury of normal tissues and, eventually, may cause a lethal shock syndrome. This toxicity implies severe limitations for the therapeutic use of TNF-alpha. Reactive oxygen intermediates (ROls) are involved in TNF-alpha-induced cell killing. Different studies are consistent with the hypothesis that tumour cell sensitivity to TNF-alpha is related to its capacity to buffer oxidative attack. Recently, we have demonstrated that the sensitivity of Ehrlich ascites tumor (EAT) cells to TNF depends on their glutathione (GSH, the most prevalent nonprotein thiol in mammalian cells) content and their rate of proliferation. This is important because tumour cell populations under active proliferative states may show higher GSH levels, and drug- and/or radiation-resistant tumours have increased cellular levels of GSH. TNF-alpha induces a shift towards oxidation in the mitochondrial glutathione (mtGSH) status, a fact that is consistent with the hypothesis that mtGSH plays a key role in scavenging TNF-induced ROIs. GSH, which is not synthesized within mitochondria but is neccessary for their normal function, needs to be taken up from the cytosol through a high affinity multicomponent transport system. In consequence, different approaches that lead to depletion of mtGSH may improve the anticancer efficacy of TNF-alpha both in vitro and in vivo. As an example, EAT-bearing mice fed a glutamine-enriched diet (GED) show a selective increase of glutamate content witihin the tumour cells. Glutamate inhibits GSH uptake by tumour mitochondria and leads to a selective depletion of mtGSH content (not found in mitochondria of normal cells) to approx. 57% of the level found in tumour mitochondria of mice fed a standard diet (SD). Administration of rhTNF-alpha, which increases generation of mitochondrial ROIs, to EAT-bearing mice fed a SD does not affect significantly the rate of tumour growth. However, when tumour-bearing mice fed a GED where treated with rhTNF-alpha the number of viable tumour cells was decreased to approx. 38% of controls.

Gross-alpha and gross-beta activities in airborne particulate samples. Analysis and prediction models

Measurements of gross-alpha and gross-beta activities were made every week during the years 1992-1997 for airborne particulate samples collected using air filters at a clear site. The data are sufficiently numerous to allow the examination of variations in time and by these measurements to establish several features that should be important in understanding any trends of atmospheric radioactivity. Two models were used to predict the gross-alpha and gross-beta activities. A good agreement between the results of these models and the measurements was highlighted.

Estradiol influences the LH response to met-enkephalin. An immunocytochemical and morphometric study

In order to test the possible role of estradiol in the response of the LH-adenohypophyseal cells to the administration of met-enkephalin in the albino male rat, an immunocytochemical (peroxidase-antiperoxidase), morphometric (cellular and nuclear areas and numerical density) and radioimmunoassay (LH serum levels at the moment of sacrifice) study was carried out. The intraventricular administration of met-enkephalin (150 micrograms in 25 microliters of distilled water) does not produce any changes in the parameters considered. However, when the animals were pretreated with estradiol (chronically, 15 days), met-enkephalin produced a significant decrease in all the parameters considered.

Mitochondrial glutathione depletion by glutamine in growing tumor cells

The effect of L-glutamine (Gln) on mitochondrial glutathione (mtGSH) levels in tumor cells was studied in vivo in Ehrlich ascites tumor (EAT)-bearing mice. Tumor growth was similar in mice fed a Gln-enriched diet (GED; where 30% of the total dietary nitrogen was from Gln) or a nutritionally complete elemental diet (SD). As compared with non-tumor-bearing mice, tumor growth caused a decrease of blood Gln levels in mice fed an SD but not in those fed a GED. Tumor cells in mice fed a GED showed higher glutaminase and lower Gln synthetase activities than did cells isolated from mice fed an SD. Cytosolic glutamate concentration was 2-fold higher in tumor cells from mice fed a GED ( approximately 4 mM) than in those fed an SD. This increase in glutamate content inhibited GSH uptake by tumor mitochondria and led to a selective depletion of mitochondrial GSH (mtGSH) content (not found in mitochondria of normal cells such as lymphocytes or hepatocytes) to approximately 57% of the level found in tumor mitochondria of mice fed an SD. In tumor cells of mice fed a GED, 6-diazo-5-norleucine- or L-glutamate-gamma-hydrazine-induced inhibition of glutaminase activity decreased cytosolic glutamate content and restored GSH uptake by mitochondria to the rate found in EAT cells of mice fed an SD. The partial loss of mtGSH elicited by Gln did not affect generation of reactive oxygen intermediates (ROIs) or mitochondrial functions (e.g., intracellular peroxide levels, O(2)(-)(*) generation, mitochondrial membrane potential, mitochondrial size, adenosine triphosphate and adenosine diphosphate contents, and oxygen consumption were found similar in tumor cells isolated from mice fed an SD or a GED); however, mitochondrial production ROIs upon TNF-alpha stimulation was increased. Our results demonstrate that glutamate derived from glutamine promotes an inhibition of GSH transport into mitochondria, which may render tumor cells more susceptible to oxidative stress-induced mediators.

Growth-associated changes in glutathione content correlate with liver metastatic activity of B16 melanoma cells

B16 melanoma (B16M) was used to study the relationship between glutathione (GSH) metabolism and the metastatic activity of malignant cells. GSH content increased in B16M cells during the initial period of exponential growth in vitro, to reach a maximum of 37 +/- 3 nmol/10(6) cells 12 h after plating, and then gradually decreased to control values (10 +/- 2 nmol/10(6) cells) when cultures approached confluency. On the contrary, glutathione disulphide (GSSG) levels (0.5 +/- 0.2 nmol/10(6) cells) and the rate of glutathione efflux (GSH + GSSG) (2.5 +/- 0.4 nmol/10(6) cells per h) remained constant as B16M grew. Changes in enzyme activities involved in GSH synthesis or the glutathione redox cycle did not explain shifts in the glutathione status (GSH/GSSG). However, two facts contributed to explain why GSH levels changed within B16M cells: a) high intracellular levels of GSH induced a feed-back inhibition of its own synthesis in B16M cells from cultures with low cellular density (LD cells); b) transport of cyst(e)ine, whose availability is the major rate-limiting step for GSH synthesis, was limited by cell-cell contact in cultures with high cellular density (HD cells). Intrasplenic injection of B16M cells with high GSH content (exponentially-growing cultures) showed higher metastatic activity in the liver than cells with low GSH content (cells at confluency). However, when low GSH-content cells (HD cells) were incubated in the presence of GSH ester, which rapidly enters the cell and delivers free GSH, their metastatic activity significantly increased. Our results demonstrate that changes in GSH content regulate the metastatic behaviour of B16M cells.

[Death caused by designer drugs]

OBJECTIVE

To draw pediatrician's attention to the risks of the use of designer drugs among adolescents and to review the problem.

MATERIAL AND METHODS

We report the case of a 15-year-old girl admitted for seizures, who rapidly developed acute liver failure and died. Clinical and pathological details are reviewed.

COMMENT

The use of designer drugs has increased considerably amongst Spanish adolescents and has been related to deaths in young adults with a variety of symptoms. Differential diagnosis should be made with the adverse effects of recreational drugs when clinical symptoms are confusing and in any unexplained deaths. Information on the effects of designer drugs should be disseminated among the population.

Glial fibrillary acidic protein-like immunoreactive ependymal elements in the third ventricle of the rat. A study at different stages of development

Using the peroxidase-antiperoxidase method a study was made of the cells immunoreactive to glial fibrillary acidic protein (GFAP) anti-serum in the ependyma of the third ventricle of the rat at different stages of growth. Most of the ependymal cells of the third ventricle were seen to be unreactive to this protein; however, it was sometimes possible to observe some GFAP-immunoreactive ependymocytes and occasionally other immunoreactive cellular types, such as tanycytes and supraependymal cells. Despite this, the most frequent localization of the elements immunoreactive to the protein adopted the shape of an immunoreactive subependymal band situated parallel to the ventricular wall. As the weights of the animals increased an increase in the elements immunoreactive to this protein could be observed in all the zones considered, there being no differences between the male and female animals.

Swim stress enhances the NADPH-diaphorase histochemical staining in the paraventricular nucleus of the hypothalamus

Regulatory control of the hypothalamic-pituitary-adrenocortical axis (HPA) originates principally from the paraventricular nucleus (PVN), which contains an important population of nitric oxide synthesizing (NOS) neurons. In the present study, the effect of swim stress upon these neurons was investigated by means of the NADPH-diaphorase (ND) histochemical technique. A significant increase in the number of ND-neurons was observed following forced swim, especially after 30 min. These data confirm the involvement of NOS-neurons of the PVN in the response to different types of acute stressors.

Immunohistochemical evidence of the presence of aromatase P450 in the rat hypophysis

In order to analyze whether aromatase is present in the hypophysis of adult rats, we have performed an immunohistochemical study in young adult male and female rats. Our study has revealed that the hypophysis of adult rats contains aromatase, although marked differences are found between the sexes. The hypophyses of male rats have cells immunoreactive for the enzyme, 34.40% of these hypophyseal cells showing reaction. By contrast, cells from female rats show very little reaction, only 0.84% of them being reactive. No significant differences in the percentage of immunoreactive cells between one phase and another are observed during the estrous cycle. Our results point to the immunohistochemical expression of aromatase in the hypophysis of adult rats and at the same time suggest that its expression is sex-dependent. The enzyme may therefore be involved in the regulation of adenohypophyseal cytology by androgens.

Changes in glutathione status and the antioxidant system in blood and in cancer cells associate with tumour growth in vivo

The relationship among cancer growth, the glutathione redox cycle and the antioxidant system was studied in blood and in tumour cells. During cancer growth, the glutathione redox status (GSH/GSSG) decreases in blood of Ehrlich ascites tumour-bearing mice. This effect is mainly due to an increase in GSSG levels. Two reasons may explain the increase in blood GSSG: (a) the increase in peroxide production by the tumour that, in addition to changes affecting the glutathione-related and the antioxidant enzyme activities, can lead to GSH oxidation within the red blood cells; and (b) an increase of GSSG release from different tissues into the blood. GSH and peroxide levels are higher in the tumour cells when they proliferate actively, however GSSG levels remain constant during tumour growth in mice. These changes associate with low levels of lipid peroxidation in plasma, blood and the tumour cells. The GSH/GSSG ratio in blood also decreases in patients bearing breast or colon cancers and, as it occurs in tumour-bearing mice, this change associates with higher GSSG levels, especially in advanced stages of cancer progression. Our results indicate that determination of glutathione status and oxidative stress-related parameters in blood may help to orientate cancer therapy in humans.

Cell proliferation and apoptosis of thyroid follicular cells are involved in the involution of experimental non-tumoral hyperplastic goiter

To assess the involvement of cellular inhibition and the appearance of apoptosis in regression of the hyperplastic thyroid gland towards normality, an experimental design was used to elicit non-toxic goiter by inducing hyperplastic goiter in rats by treatment with methimazole. We performed a morphological and PCNA immunocytochemical study together with in situ end labelling with bromodeoxyuridine in thyroid glands of rats receiving methimazole in their drinking water over 21 days after which they were allowed a recovery period of 0, 12, 24, 36, 48 and 72 h and 7, 14, 21 and 44 days. Serum T3 and T4 levels were found to be very low in the methimazole-treated animals although they increased after the goitrogenic compound had been withdrawn. Inhibition of cell proliferation and the burst of apoptosis play important roles in the regression of hyperplastic goiter in rats. Cell proliferation, which was strongly stimulated during goiter, fell significantly at 24 h, thereafter decreasing gradually as the recovery period progressed. Isolated cases of thyrocyte necrosis were observed ultrastructurally. Light and transmission electron microscopy revealed the existence of thyroid apoptosis with respect to the development of the study over time. Most apoptotic thyrocytes became detached from the follicular epithelium and later underwent cellular degeneration in the follicular lumen. The remaining apoptotic cells retracted their cytoplasm, lost contact with the follicular lumen and became located at the base of the follicles. The percentage of apoptosis showed that during the first week of thyroid involution apoptosis was already present but with low percentages while maximum values were attained at 21 days of survival. Our results suggest that, in the rat, during the return of thyroid follicular cells to normality after methimazole-induced hyperplastic goiter a balance arises between proliferation and cell death and that this balance is due to the inhibition of cellular proliferation and, secondarily, to the appearance of apoptosis, which becomes particularly evident towards the end of the first week after withdrawing the goitrogenic agent.

Reduced nicotinamide adenine dinucleotide phosphate-diaphorase activity in the paraventricular nucleus of the rat hypothalamus is modulated by estradiol

Based on previous studies demonstrating that reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase (ND) activity is modulated by estradiol and the discovery of a new subtype of estrogen receptor highly expressed in the paraventricular nucleus of the hypothalamus (PVN), a possible estrogen influence on this activity was investigated in the neuronal populations (magno- and parvicellular) of this nucleus. Cryostat sections were cut and processed for the histochemical detection of the ND activity. Following ovariectomy (14 days), numerical data displayed a slight decrease in the number of ND-neurons, especially in the posterior magnocellular and the medial parvicellular subdivisions, which was reversed after daily treatment with estradiol benzoate. Administration of estradiol benzoate to male rats (14 days) induced a significant increase (P < 0.05) in the number of ND-neurons, mainly at the level of the posterior magnocellular subdivision. These data indicate that paraventricular ND-neurons are influenced by estradiol.

Corticosterone induces hypoactivity of prolactin-immunoreactive cells

In order to determine whether corticosterone regulates activity of rat lactotrophs by acting directly at the pituitary level, immunohistochemical studies were carried out in adrenalectomized rats, subjected or not to treatment with corticosterone or colchicine, and in monolayer cultures after incubation with corticosterone. Adrenalectomy increased cellular and nuclear areas (p<0.01) of prolactin-immunoreactive cells without affecting their cytoplasmic area. Similar results were found in adrenalectomized and colchicine-treated animals. Corticosterone reversed the effects of adrenalectomy, although normal values were partially reversed. In cultured pituitary cells, exposure to corticosterone reduced numerical density and cellular, cytoplasmic and nuclear areas with respect to control dishes. Morphological differences in shape, arrangement and nuclear features were observed after treatment with corticosterone. These results demonstrate an inhibitory effect of corticosterone on the activity of rat pituitary prolactin cells and suggest that corticosterone induces hypoactivity by acting on the pituitary prolactin cells of male rats.

Partial co-existence of NADPH-diaphorase and acetylcholinesterase in the hypothalamic magnocellular secretory nuclei of the rat

Co-localization of NADPH-diaphorase (ND) and acetylcholinesterase (AChE) activities were explored in the magnocellular secretory nuclei of the rat hypothalamus by means of a double histochemical staining of the same sections. Partial co-existence was found in all the nuclei studied (paraventricular, supraoptic, fornicals and circular nuclei). No particular location of the neurons expressing both markers was found, although in the paraventricular nucleus all of them (ND +, AChE + and neurons expressing both markers) were preferentially located in the magnocellular subdivisions whereas in the parvicellular ones only some neurons belonging to all three types were detected, mainly located in the periventricular and medial subdivisions. The lowest degree of co-existence was found at the level of the main magnocellular nuclei (supraoptic and paraventricular) when compared with the accessory magnocellular nuclei, especially the posterior fornical and the circular nuclei. These results extend previous data on the chemical nature of the neurons producing nitric oxide in the neurosecretory nuclei and the possible functional role of this atypical messenger in the hypothalamus.