PubMed Health⌕ Search

Biomedical subjects

A Theodorou

Publications and source records attributed to A Theodorou.

At least 19 recordsLinked to original sources
PubMed2005

Field data analysis and application of a complex water column biogeochemical model in different areas of a semi-enclosed basin: towards the development of an ecosystem management tool.

The Pagasitikos gulf ecosystem is studied through the analysis of experimental field data acquired during several monitoring projects and the application of a complex biogeochemical model. The gulf was separated into three different parts (internal, top central-external, bottom central-external) according to the patterns exhibited by the key ecosystem indicators. Unlike other semi-enclosed gulfs Pagasitikos can be characterised as meso-oligotrophic undergoing periods of P or N limitation. Although the signal of nutrient inputs is not very clear in the field data, their importance is assessed through simulation. Increased phosphate concentrations either due to mixing or due to anthropogenic activities can result in phytoplanktonic blooms with significant contribution by diatoms. The effect of hydrodynamic patterns on primary production has been demonstrated through ecosystem modeling indicating that due to long stratification periods, all nutrients released through the benthic regeneration are trapped in the deeper layers, developing a microbial food web. However when the thermocline erodes nutrients find their way up in the upper layers of the euphotic zone and the system turns into more classical type with primary producers growing significantly faster.

Animals↗
PubMed2002

Wireless and Web-based medical monitoring in the home.

A remote medical monitoring system is described, which continuously monitors patients' state of health. The system uses the services provided by intranets and the Internet to allow remote supervision of patients, who may be domiciled in their own home. A hardware/software prototype system has been constructed to demonstrate the use of non-invasive and minimally intrusive sensors attached to patients. Continuous real-time data is acquired, stored and processed. A wireless system or wires connect these monitor devices to the World Wide Web and, on request, information is delivered to authorized medical staff via a web browser or Wireless Application Protocol-enabled mobile telephones. Medical staff may examine real-time data or graphical information and make comparisons with historical data. Parameters may be set to select and control the data acquisition devices. The potential exists for augmentation of patient health by development of novel sensors and low-power electronic circuitry, and this research continues.

Aged↗
PubMed1997

Ragweed sensitization alters pulmonary vascular responses to bronchoprovocation in beagle dogs.

In ragweed (RW)-sensitized beagle dogs, we tested the hypothesis that reactivity of the pulmonary vasculature was enhanced with aerosolized histamine (Hist) and RW. Seven dogs were neonatally sensitized with repeated intraperitoneal RW injections, and 12 dogs were controls (Con). The dogs were anesthetized with intravenous chloralose, mechanically ventilated, and instrumented with femoral arterial and pulmonary artery catheters. Specific lung compliance (CLsp), specific lung conductance (Gsp), systemic vascular resistance index, and pulmonary vascular resistance index (PVRI) were measured before and after bronchoprovocation with Hist and RW. After Hist inhalation (5 breaths of 30 mg/ml), both Con and RW dogs had significant (P < 0.05) decreases in CLsp (-51 +/- 4 and -53 +/- 5%, respectively) and Gsp (-65 +/- 5 and -69 +/- 3%, respectively), but only RW-sensitized dogs had a significant increase in PVRI (38 +/- 10%). After RW inhalation (60 breaths of 0.8 mg/ml), only RW-sensitized dogs had significant increases (62 +/- 20%) in PVRI and decreases in Gsp (-77 +/- 4%) and CLsp (-65 +/- 7%). We conclude that, compared with Con, RW-sensitized beagle dogs have increased pulmonary vasoconstrictive responses with Hist or RW inhalation.

Allergens↗
PubMed1994

[Histological study of different organs in clinically healthy Amazon parrots].

Histologic examination of organs of clinically healthy amazons was carried out. Only variations from the chicken are presented, among others: Occurrence of a complex of vessels and many Herbst' corpuscles in the nasal cavity; evidence of a thick muscular layer as well as many Herbst' corpuscles and nerve fibers as the cover of the syrinx; demonstration of muscular trabeculae in the parabronchia; detection of an artery accompanying the testes with muscular layers reaching into the adventitia and many nerve fibers; very small numbers of active lymph follicles within the white pulp of the spleen.

Animals↗
PubMed1991

Therapeutic interchange of ampicillin-sulbactam for cefoxitin.

A therapeutic interchange program based on microbial patterns within an institution is described. A change in anaerobic susceptibility patterns, increased prevalence of enterococcal infections, and cost factors provided the rationale for the therapeutic interchange of ampicillin-sulbactam for cefoxitin. Ampicillin-sulbactam was recommended for prophylaxis in intraabdominal or gynecological surgery as well as for treatment for gynecological infections. Cefoxitin was restricted to penicillin-allergic patients and women who were pregnant or breast-feeding. The transition from cefoxitin to ampicillin-sulbactam proceeded smoothly as a result of preliminary education of pharmacists and physicians. Pharmacists participated in continuing-education programs and received concise guidelines for the interchange and follow-up instructions; physicians learned of the program from the drug newsletter published by the pharmacy department. Three months after the program began, only one physician was resistant to the interchange. After the program began, 11 antimicrobials, including cefoxitin, were used less frequently and ampicillin-sulbactam use increased. No adverse clinical consequences from the interchange were detected. A therapeutic interchange program based on institution-specific microbial patterns and educational efforts by the pharmacy department produced a change in physician prescribing.

Ampicillin↗
PubMed1985

Effects of discontinuous drug administration on the development of dopamine receptor supersensitivity during chronic trifluoperazine or cis-flupenthixol administration to rats.

Rats received continuous or discontinuous administration of trifluoperazine or cis-flupenthixol in drinking water for up to 12 months. Continuous and discontinuous trifluoperazine administration had no consistent effect on apomorphine-induced stereotyped behaviour and there was no difference between drug treatments. Continuous and discontinuous cis-flupenthixol administration enhanced apomorphine-induced stereotypy, but there was no difference in the effect of the two drug treatments. Both continuous and discontinuous administration of trifluoperazine increased the number of specific striatal 3H-spiperone binding sites (Bmax). Over the period of treatment there was no difference in the effects of the different treatments. Continuous or discontinuous cis-flupenthixol intake did not increase Bmax after 6 or 12 months intake. Continuous or discontinuous neuroleptic treatment produced no difference in functional striatal dopamine receptor activity as judged by apomorphine-induced stereotyped behaviour. Ligand binding studies also suggest that the overall change in striatal receptor function is not affected by the use of a discontinuous drug regime.

Animals↗
PubMed1984

Alterations in different populations of striatal dopamine receptors produced by 18 months continuous administration of cis- or trans-flupenthixol to rats.

Administration of cis-flupenthixol (0.8-1.2 mg/kg per day) for 18 months enhanced stereotyped behaviour induced by apomorphine, bromocriptine and lergotrile, but not that induced by amphetamine or lisuride. Catalepsy induced by acute administration of haloperidol, trifluoperazine or cis-flupenthixol was reduced by continuous chronic intake of cis-flupenthixol. The number (Bmax) and dissociation constant (KD) of specific [3H]spiperone binding sites on striatal membranes was increased by chronic administration of cis-flupenthixol, but not trans-flupenthixol. In contrast, the Bmax and KD for specific binding of [3H]N,n-propylnorapomorphine were decreased by administration of cis-flupenthixol compared to the effect of the trans-isomer. Specific binding of [3H]piflutixol was unaffected by chronic administration of cis- or trans-flupenthixol, but chronic administration of cis-flupenthixol enhanced stimulation by dopamine of the activity of striatal adenylate cyclase. As a result of chronic continuous administration of cis-flupenthixol dopamine receptors in the striatum appeared to be supersensitive to most dopamine agonists but sub-sensitive to dopamine antagonists. This was reflected by increased numbers of D-2 antagonist receptor sites of decreased affinity, but by a decreased number of agonist sites of higher affinity. The D-1 recognition sites appeared to be unaltered, but activity of adenylate cyclase stimulated by dopamine was enhanced, suggesting post-junctional changes. The D-2 receptors appear to be primarily concerned with altered function of dopamine receptors.

Adenylyl Cyclases↗
PubMed1983

Persistent increase in striatal dopamine stimulated adenylate cyclase activity persists for more than 6 months but disappears after 1 year following withdrawal from 18 months cis-flupenthixol intake.

Administration of cis-flupenthixol to rats for 18 months enhanced apomorphine-induced stereotyped behaviour, increased the number of specific [3H]spiperone binding sites in striatum and potentiated striatal dopamine stimulated cyclic AMP formation, but did not alter specific [3H]piflutixol binding. Following withdrawal of cis-flupenthixol intake, apomorphine-induced stereotypy returned to control values after 1 month and Bmax for [3H]spiperone binding returned to normal after 3 months. In contrast, the increased dopamine stimulated adenylate cyclase activity remained elevated 6 months after drug removal, but was normal 1 year after drug withdrawal.

Adenylyl Cyclases↗
PubMed1983

Alterations in cerebral dopamine function caused by administration of cis- or trans-flupenthixol for up to 18 months.

Rats received either cis-flupenthixol (0.8-1.2 mg/kg per day) or trans-flupenthixol (0.9-1.2 mg/kg per day) continuously in drinking water for periods up to 18 months. cis-Flupenthixol, but not trans-flupenthixol, initially inhibited apomorphine-induced stereotyped behaviour but by 6 months and thereafter the stereotyped response was enhanced compared to age-matched control animals. Striatal and mesolimbic homovanillic acid and 3,4-dihydroxyphenylacetic acid concentrations were elevated for up to 3 months after starting cis-, but not trans-flupenthixol intake, but thereafter levels generally fell below those for age-matched control animals. Dopamine concentrations were not altered by cis- or trans-flupenthixol administration. The number of striatal [3H]spiperone binding sites (Bmax) was decreased by 40% after 1 months' administration of cis-flupenthixol but this gradually reversed, such that by 18 months a 40% increase in Bmax was apparent. Administration of trans-flupenthixol decreased Bmax up to 3 months but thereafter values were not different from those found in age-matched control animals. The dissociation constant (KD) for [3H]spiperone binding in striatum was not altered by 6 months cis-flupenthixol intake, but then increased as drug administration continued. trans-Flupenthixol administration did not alter striatal KD values. Bmax for [3H]spiperone binding to mesolimbic preparations was not altered by up to 12 months cis-flupenthixol intake, but was decreased after 18 months drug administration. cis-Flupenthixol administration had no effect on mesolimbic KD values. Administration of trans-flupenthixol for up to 18 months did not alter mesolimbic Bmax or KD values for [3H]spiperone binding.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1982

Repeated administration of sulpiride for three weeks produces behavioural and biochemical evidence for cerebral dopamine receptor supersensitivity.

Administration of sulpiride (2 X 100 mg/kg i.p.) or haloperidol (5 mg/kg i.p.) to rats for 3 weeks with subsequent withdrawal for 3 or 4 days induced cerebral dopamine receptor supersensitivity. Apomorphine-induced stereotyped behaviour after drug withdrawal was enhanced by pretreatment with either haloperidol or sulpiride both of which increased the number of specific striatal binding sites (Bmax) for [3H]spiperone, [3H]N,n-propylnorapomorphine and [3H]sulpiride. Neither drug altered the dissociation constant (KD) for the ligand binding assays. Striatal dopamine sensitive adenylate cyclase activity was unaltered by such a pretreatment with either haloperidol or sulpiride. The data show that sulpiride, like haloperidol, is capable of inducing behavioural and biochemical supersensitivity of cerebral dopamine receptors.

Adenylyl Cyclases↗
PubMed1981

Subchronic treatment with the tricyclic antidepressant DMI increases isolation-induced fighting in rats.

Male rats treated with desmethylimipramine (DMI) (20 mg/kg for 7 days) were more likely than controls to attack an intruder rat placed in their home cage; they were also more likely to submit when attacked by the intruder. These behavioural changes were not seen at lower doses of DMI. Similar results were obtained in experiments in which is drugged animal and a control were placed together in a "neutral" cage; in this paradigm it was also found that lower doses of DMI were effective, provided that either the period of drug treatment was increased, or a delay of 3-4 days after withdrawal of DMI preceded behavioural testing. A dose dependent resistance to handling developed during drug treatment; drugged animals also showed weight loss and decreased open-field activity. In previous studies, acute treatment with tricyclic antidepressants has not been found to increase fighting; the present results underline the importance of chronic drug studies.

Aggression↗
PubMed1981

Kainic acid lesions of striatum and decortication reduce specific [3H]sulpiride binding in rats, so D-2 receptors exist post-synaptically on corticostriate afferents and striatal neurons.

Unilateral kainic acid lesions of rat striatum reduced specific striatal [3H]spiperone and [3H]sulpiride binding sites (Bmax) by 52 and 67% respectively compared with the intact side. The dissociation constant (KD) for [3H]spiperone binding was unchanged but that for [3H]sulpiride binding was reduced. Specific striatal [3H]spiperone and [3H]sulpiride binding was reduced by 22 and 37% respectively in unilateral decorticate animals, but there was no change in KD. Unilateral 6-hydroxydopamine lesions of the medial forebrain bundle caused no change in striatal [3H]spiperone binding sites or KD value, but produced a 27% increase in [3H]sulpiride binding sites with no change in KD. These data support the hypothesis of D-2 receptors located on cortico-striate glutamate fibres, but also indicate the presence of both D-1 and D-2 receptors on the cell bodies of striatal neurons.

Animals↗
PubMed1980

Changes in rat striatal dopamine turnover and receptor activity during one years neuroleptic administration.

Administration of trifluoperazine (2.5--3.5 mg/kg/day p.o.) or thioridazine (30--40 mg/kg/day) for up to 1 year initially increased homovanillic acid and 3,4-dihydroxyphenylacetic acid concentrations in striatum. However, by 1 month and thereafter metabolite levels returned almost to control values. Dopamine concentrations were elevated after 3 months administration of both drugs and also after 12 months administration of trifluoperazine. Trifluoperazine administration for 1 month produced a marked increase in the dissociation constant (KD) for striatal 3H-spiperone binding but a reduction in receptor numbers. Thereafter receptor numbers increased at 6 and 12 months in both trifluoperazine and thioridazine treated animals compared to control values. The KD for both drug treated groups returned to normal at 6 months; however, by 12 months drug treated animals again demonstrated high KD values. Dopamine stimulation of striatal adenylate cyclase was inhibited after administration of trifluoperazine or thioridazine for 1 week or 1 month. However, by 6 and 12 months this effect was replaced by an enhanced stimulation. Administration of lower doses of trifluoperazine (0.7--0.9 mg/kg/day p.o.) or thioridazine (6--9 mg/kg/day p.o.) for up to 1 year produced similar although generally less marked changes in these biochemical indices of dopamine function. This study provides evidence of biochemical changes which parallel the behavioural findings of enhanced dopamine receptor activity that occur during continuous long-term neuroleptic administration to rodents.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1980

Cerebral dopamine function in rats following withdrawal from one year of continuous neuroleptic administration.

Continuous administration of trifluoperazine (2.5--3.5 mg/kg/day) or thioridazine (30--40 mg/kg/day) to rats for 12 months enhanced the stereotyped response to apomorphine (0.5 mg/kg s.c.), increased dopamine 1--150 muM) stimulation of striatal adenylate cyclase, increased KD and Bmax for dopamine (10(-4) M) specific 3H-spiperone striatal binding and produced spontaneous mouthing movements. On drug withdrawal, spontaneous locomotor activity was enhanced after 2 weeks and the enhanced stereotyped response was maintained for up to 1 month. Spontaneous mouthing had disappeared 2 weeks after drug withdrawal. The increase in Bmax for 3H-spiperone binding was maintained for up to 3 months after drug removal, but KD reverted to control levels by 2 weeks. In contrast, the dopamine stimulation of striatal adenylate cyclase remained enhanced for the 6 month withdrawal period. Administration of trifluoperazine (0.7--0.9 mg/kg/day) or thioridazine (6--8 mg/kg/day) for 12 months produced a less marked effect than administration of the higher dose. No enhancement of effect was observed on drug withdrawal and the initial changes disappeared rapidly on removal of drug. Supersensitivity of striatal dopamine mechanisms produced by continuous long-term neuroleptic administration differs from that produced by shorter treatment periods since no enhancement of effect occurs on drug withdrawal. The behavioural and biochemical components of the supersensitivity show variable time courses and in particular the enhanced stimulation of striatal adenylate cyclase persists for at least 6 months. Such effects may be of relevance to tardive dyskinesias in man.

3,4-Dihydroxyphenylacetic Acid↗