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F Santana

Publications and source records attributed to F Santana.

8 recordsLinked to original sources
PubMed2006

Monitoring biofilm thickness using a non-destructive, on-line, electrical capacitance technique.

The present study was designed to evaluate indirect, non-invasive, on-line measurement of biofilm thickness using an electrical capacitance technique. Several assays were carried out and the results showed that, at a frequency of 1 kHz, electrical capacitance could be used to measure biofilm thickness indirectly (with a correlation coefficient of 0.9495). The reproducibility revealed by the assays was also highly satisfactory. However, in contrast to what was expected, there was an inverse relationship between electrical capacitance and biofilm thickness, i.e. electrical capacitance diminished with the increase in the biofilm thickness. The tests were also carried out at different frequencies (1 kHz, 10 kHz and 100 kHz).

Algorithms↗
PubMed2006

A characterization of selected endocrine disruptor compounds in a Portuguese wastewater treatment plant.

Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a major cause for concern and have led to a demand for new screening methods. The identification and quantification of endocrine disruptor compounds at wastewater treatment plant is of major interest to assess the endocrine activity of wastewater treatment plant discharges into the environment. This study consists of a preliminary survey of concentrations of previously selected endocrine disruptor compounds, undertaken to establish environmental concentrations and to support a biological program assay exposing freshwater fish to them. Selected endocrine disrupting chemicals (APEs, bisphenol A and 17 beta-estradiol) were measured in samples from a wastewater treatment plant located in Lisbon (Portugal), using recent commercial enzyme-linked immunosorbent assay kits and also LC-MS/MS. The results show that the wastewater treatment plant treatment process is efficient on the removal of target endocrine disruptor compounds. However, environmentally significant concentrations are still present in the treated effluent. The results also show that enzyme-linked immunosorbent assay kit is suitable for routine analysis of the selected compounds. The results are also useful since the wastewater treatment plant is located in a Mediterranean region, which results in an effluent with its own characteristics.

Benzhydryl Compounds↗
PubMed2002

Nitrite removal in a submerged biofilter.

Nowadays submerged filters seem to be the preferred technology for denitrification purposes. Optimisation of biological nitrogen has recently been tried based the nitrate shunt in order to save two of the involved steps. Former studies have shown that a build-up of nitrite can be achieved by an appropriate control of the nitrification process either in suspended cultures or in fixed cultures. An experimental plan was conducted to study the effect of different types of carbon source (acetate, ethanol and urban wastewater) on the performance of a submerged down flow biofilter, as well as the influence of the hydraulic loading. Results have shown that maximum nitrogen removal rates were similar for acetate and ethanol attaining values significantly higher than for urban waste water. On the other hand, nitrogen massic loading appeared to be the limiting factor for efficiency rather than hydraulic loading.

Biodegradation, Environmental↗
PubMed1999

Calcium channel subtypes and exocytosis in chromaffin cells: a different view from the intact rat adrenal.

In the intact rat adrenal gland perfused with an oxygenated Krebs-bicarbonate solution at 37 degrees C, the electrical field stimulation of splanchnic nerves (100 V, 0.5 ms duration, 10 Hz during 10 s) produced transient catecholamine release peaks that were reproduced in subsequent stimuli, applied at 8-min intervals. Omega-Conotoxin GVIA (0.3 microM) caused only a modest inhibition of the secretory response, suggesting that the N-subtype of voltage-dependent Ca2+ channels are scarcely involved in such a response. Both omega-conotoxin MVIIC (1 microM) and furnidipine (1 microM) halved the secretion, suggesting that the L- and P/Q-types of Ca2+ channels were involved. N-type Ca2+ channels appear to be involved in the maintenance of secretion in response to sustained stimulus since omega-conotoxin GVIA (0.3 microM) reduced the catecholamine output to 28%. When secretion was elicited by acetylcholine (10 microM), furnidipine reduced the catecholamine release by 50% and omega-conotoxin MVIIC by 40%, whereas omega-conotoxin GVIA did not modify the response. The K+-induced secretory responses (23.6 mM K+, 15 s) were reduced 75% by furnidipine and 45% by omega-conotoxin MVIIC, indicating that this type of stimulation preferentially recruited L-type channels. These data show that electrical stimulation recruits Ca2+ channel subtypes different from those recruited by direct depolarization of chromaffin cells.

Acetylcholine↗
PubMed1997

Interaction between G protein-operated receptors eliciting secretion in rat adrenals. A possible role of protein kinase C.

Catecholamine release induced by angiotensin II, histamine, bradykinin and methacholine from the rat adrenal gland perfused in vitro was studied under conditions in which the activity of protein kinase C (PKC) was modified. Perfusion of glands with 10 nM bradykinin abolished, in a reversible way, the secretion induced by short pulses of angiotensin II, histamine and methacholine but did not modify the release evoked by 23.6 mM KCl (high K+). Perfusion with histamine or methacholine (30 microM) inhibited the secretion induced by the other agents by 30-50%, whereas incubation with angiotensin II (100 nM) caused little or no reduction in the release evoked by the other agents. The treatment of glands with 1 nM of the PKC activator phorbol 12,13-dibutyrate (PDBu) suppressed the responses induced by angiotensin II, histamine and methacholine, did not affect those evoked by bradykinin, and potentiated the secretion evoked by high K+. The adenylate cyclase stimulator forskolin (1 microM) did not affect the basal secretion but strongly potentiated the release evoked by all secretagogues used, suggesting a role for protein kinase A (PKA) downstream of the receptor. The PKC inhibitor Ro-31-8220 partially reversed the inhibitory effect of bradykinin. Our results suggest that angiotensin II, histamine and muscarinic receptors share some common transduction mechanism that is regulated by PKC. PKC activity was enhanced by these agents PDBu >> bradykinin = histamine > methacholine = angiotensin II. Bradykinin receptor transduction does not appear to be regulated by PKC.

Adrenal Glands↗
PubMed1987

Lifetime prevalence of specific psychiatric disorders among Mexican Americans and non-Hispanic whites in Los Angeles.

The lifetime prevalence of specific DSM-III-defined psychiatric disorders among 1243 Mexican-American and 1309 non-Hispanic white residents of two Los Angeles communities is reported from the Los Angeles site of the Epidemiologic Catchment Area (ECA) research study. Results from household interviews in response to the National Institute of Mental Health Diagnostic Interview Schedule revealed overall rates of disorders for the total Los Angeles sample and ethnic subsamples that were similar to rates reported from the initial three ECA sites. Non-Hispanic whites reported far more drug abuse/dependence and more major depressive episodes than Mexican Americans. Young non-Hispanic white women reported high rates of major depressive episodes and drug abuse/dependence. Alcohol abuse/dependence is highly prevalent among Mexican-American and non-Hispanic white men of any age. Mexican-American women infrequently abuse or become dependent on drugs or alcohol at any age. Dysthymia, panic disorder, and phobia are somewhat more prevalent among Mexican-American women over 40 years of age compared with both non-Hispanic white women over and Mexican-American women under 40 years of age. Antisocial personality is predominantly a disorder of young men of both ethnic groups.

Adult↗
PubMed1987

Expressed emotion and schizophrenic outcome among Mexican-American families.

This study has demonstrated that among low-income, relatively unacculturated Mexican-American households, a high level of expressed emotion on the part of key relatives significantly increases the risk of relapse for remitted schizophrenics who return home to live with their families after hospital discharge. This cross-cultural replication of earlier research findings in London and southern California suggests that critical, hostile, or emotionally overinvolved attitudes and behaviors may be general major stressors that adversely influence the fragile adaptation of schizophrenic individuals in diverse cultural settings. The finding of a lower prevalence of high levels of expressed emotion among Mexican-American compared to Anglo-American and British households lends support to the hypothesis that intrafamilial behaviors may account for different schizophrenic outcomes in different cultures.

Attitude to Health↗