Involvement of serotonin and dopamine in the mechanism of action of novel antidepressant drugs: a review

Several hypotheses regarding the physiopathology of major depression exist. Attention has been focused on cerebral monoaminergic systems, the dysfunction of which is thought to underlie various aspects of depressive symptomatology. There is extensive literature describing the involvement of serotonergic and dopaminergic systems in the mechanism of action of antidepressant drugs. However, a unitary analysis of the data in terms of interaction between different monoaminergic systems is still lacking. In this article, studies reporting the biochemical, behavioral, and clinical effects of tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), selective blockers of presynaptic dopamine (DA) receptors, and antagonists of serotonin-2 (5-hydroxytryptamine-2 [5-HT2]) receptors were reviewed. Analysis of the current literature indicates that long-term treatment with antidepressants causes adaptive changes of the serotonergic and dopaminergic systems. In particular, long-term administration of TCAs enhances the responsiveness of postsynaptic serotonin receptors to iontophoretically applied serotonin and potentiates the behavioral responses to both direct and indirect dopaminergic agonists. Repeated administration of SSRIs and MAOIs increases serotonergic transmission by desensitizing the inhibitory 5-HT1A somatodendritic and terminal 5-HT1B/1D autoreceptors. Selective blockers of DA autoreceptors exert their antidepressant effect by enhancing DA release. A similar mechanism of action could be hypothesized for 5-HT2 receptor antagonists. There is general agreement that the clinical effect of antidepressant drugs, which becomes evident only after long-term treatment, is caused by their ability to induce adaptive changes of the monoaminergic systems. Increases in both serotonergic and dopaminergic function have been consistently found after long-term treatment with various classes of antidepressant drugs. Recent studies have focused on the functional interaction between the serotonergic and dopaminergic systems to explain the mechanism of the antidepressant action of SSRIs and 5-HT2 antagonists.

Urinary NMP22 for the detection of recurrence after transurethral resection of transitional cell carcinoma of the bladder: experience on 137 patients

OBJECTIVES

To evaluate the nuclear matrix protein 22 (NMP22) test in the management of patients after transurethral resection (TUR) of recurrent transitional cell carcinoma of the bladder.

METHODS

The NMP22 test was performed in 137 patients: in 42 patients, a bladder recurrence was detected by cystoscopy and histologically confirmed; 95 patients were recurrence-free at cytology and cystoscopy performed at least 3 months after TUR.

RESULTS

In patients with tumoral recurrence, the mean NMP22 value was 54.8 U/mL. The false-negative rate was 28.5%. In recurrence-free patients, the mean NMP22 value was 22.8 U/mL. The specificity of the NMP22 test was 61%. Higher NMP22 mean values (29.6 versus 15.8 U/mL) were found in patients who underwent intravesical chemotherapy or immunotherapy.

CONCLUSIONS

Despite its good sensitivity, the NMP22 test cannot be adopted as a routine tool in the surveillance after TUR of patients with superficial bladder cancer because of its low specificity.

Effects of acute and repeated administration of amisulpride, a dopamine D2/D3 receptor antagonist, on the electrical activity of midbrain dopaminergic neurons

Electrophysiological techniques were used to study the effects of amisulpride, a D2/D3 dopamine receptor blocker, on the activity of dopaminergic neurons in the substantia nigra pars compacta (SNc) and the ventral tegmental area (VTA). Administration of single bolus doses of amisulpride (8-32 mg/kg i.v.) induced a dose-dependent increase in the basal activity of dopaminergic neurons, in both the SNc and the VTA. The effect of amisulpride was more evident in the VTA, where it elicited a maximal excitation of 38.5 +/- 12%, whereas in the SNc it caused a peak excitation of only 22.1 +/- 9.8%. Amisulpride also increased the bursting activity of dopaminergic neurons in the VTA but not in the SNc. Microiontophoretic application of amisulpride (10-40 nA) into the SNc and the VTA caused an increase in the basal firing rate of the majority of dopaminergic neurons sampled. The excitation induced by 40 nA amisulpride was more marked in the VTA (36.1 +/- 21%) than in the SNc (25.0 +/- 18%). Moreover, microiontophoretic amisulpride (40 nA) increased the bursting activity of dopaminergic neurons in the VTA only. Repeated administration of amisulpride (20 and 50 mg/kg i.p.) for 21 consecutive days produced a significant decrease in the number of spontaneously active dopaminergic neurons in the VTA but not in the SNc. Repeated admistration of haloperidol (0.5 mg/kg i.p. ) decreased the number of dopaminergic cells both in the SNc and the VTA. The effect of repeated admistration of amisulpride on the activity of VTA dopaminergic neurons was reversed by apomorphine, suggesting that these neurons were probably under a state of depolarization block. Taken together, these data confirm previous findings indicating that low doses of amisulpride preferentially increase dopaminergic transmission in the mesolimbic system. Moreover, results obtained from long-term experiments are consistent with clinical data indicating that amisulpride given at high doses is an effective antipsychotic agent, associated with a low incidence of extrapyramidal side effects.

Selective serotonin reuptake inhibitors reduce the spontaneous activity of dopaminergic neurons in the ventral tegmental area

Electrophysiological techniques were used to study the effects of paroxetine, sertraline, and fluvoxamine on the basal activity of dopaminergic neurons in the ventral tegmental area (VTA) of rats. Acute i.v. administrations of paroxetine (20-1280 microg/kg), sertraline (20-1280 microg/kg), and fluvoxamine (20-1280 microg/ kg) caused a slight but significant reduction in the firing rate of the VTA dopaminergic cells studied. Paroxetine produced a maximal inhibitory effect of 10 +/- 11% at the cumulative dose of 160 microg/kg. Sertraline induced a dose-related inhibition of VTA dopaminergic neurons, which reached its maximum (10 +/- 7%) at the cumulative dose of 1280 microg/kg. The effect of fluvoxamine on the basal firing rate of VTA dopaminergic neurons was more pronounced as compared to that of paroxetine and sertraline, in that it produced a maximal inhibition of 17 +/- 12% at the cumulative dose of 1280 microg/kg. Acute i.v. injections of paroxetine (20-1280 microg/kg), sertraline (20-1280 microg/kg), and fluvoxamine (20-5120 microg/kg) caused a dose-dependent decrease in the basal firing rate of serotonergic neurons in the dorsal raphe nucleus (DRN). Paroxetine and sertraline stopped the spontaneous firing of serotonergic neurons at the cumulative dose of 1280 microg/kg, whereas fluvoxamine reached the same effect only at the cumulative dose of 5120 microg/kg. Pretreatment with the 5-HTA1A receptor antagonist tertatolol (1 mg/kg, i.v.) reduced the inhibitory effects of paroxetine, fluvoxamine, and sertraline on the basal activity of serotonergic neurons in the DRN. Administration of tertatolol induced a 15-fold increase in the ED50 for fluvoxamine. The antagonistic effect of tertatolol was much less evident in blocking the inhibitory action exerted by paroxetine and sertraline on the activity of serotonergic neurons. Pretreatment with tertatolol (1 mg/kg, i.v.) potentiated the inhibitory effect of fluvoxamine on the basal activity of VTA dopaminergic neurons. Tertatolol did not affect the inhibitory action exerted by paroxetine and sertraline on these neurons. It is concluded that inhibition of the basal firing rate of dopaminergic neurons in the VTA is a common characteristic of selective serotonin reuptake inhibitors (SSRIs). The effects of SSRIs on VTA dopaminergic cell activity might be relevant for their therapeutic action and may explain the origin of the reported cases of akathisia.

Biodegradation of the herbicide Diuron in soil by indigenous actinomycetes

Three actinomycete strains isolated from soil treated with 2,4-D were able to degrade the herbicide Diuron in vitro. Strain CCT 4916 was the most efficient, degrading up to 37% of applied Diuron (100 mg Kg-1 soil) in 7 days, as measured by HPLC and UV/VIS spectroscopy. All strains showed protease and urease activity; intracellular activity of metapyrocatechase and pyrocatechase were not found. Actinomycete strain CCT 4916 produced manganese peroxidase, which could be potentially related to degradation of Diuron.

Selective blockade of serotonin2C/2B receptors enhances dopamine release in the rat nucleus accumbens

The effects of mesulergine (100 and 200 microg/kg s.c.), SB 206553 (1 and 2.5 mg/kg i.p.), RP 62203 (2.5 and 4 mg/kg i.p.) and ritanserin (630 microg/kg i.p.) were studied on the extracellular concentration of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens of chloral hydrate-anesthetized rats, using intracerebral microdialysis. Mesulergine, a non selective serotonin2C/2B/2A (5-HT2C/2B/2A) receptor antagonist, significantly increased DA release, which reached a peak level (+ 20%) 60 min after drug injection and slowly returned back to baseline values. Mesulergine also caused a dose-dependent increase in DOPAC outflow. Pretreatment with mesulergine (200 microg/kg) did not change the inhibition of DA release induced by apomorphine (100 microg/kg), whereas it prevented the reduction of DOPAC outflow induced by apomorphine (100 microg/kg). Administration of SB 206553, a selective blocker of 5-HT2C/2B receptors, dose-dependently increased DA outflow. The dose of 2.5 mg/kg SB 206553 caused a linear increase of DA output which reached a peak (+75%) 40 min after injection, while 1 mg/kg induced a more gradual increase of DA release which peaked (+54%) 60 min after administration of the drug. Treatment with RP 62203, a selective 5-HT2A receptor antagonist, did not produce any significant effect on DA outflow. Administration of ritanserin, a mixed 5-HT2A/2C receptor antagonist, did not cause any significant change of DA and DOPAC outflow. Taken together, these data indicate that selective blockade of 5-HT2/2B receptor subtypes increases DA release in the rat nucleus accumbens.

Systematics and environmental application of the genus Trichoderma

Trichoderma, an anamorphic Hypocreaceae (class Ascomycetes), is common in the environment, especially in soils. Species of this genus have been used in the production of cellulolytic and hemicellulolytic enzymes, biological control of plant disease, biodegradation of chlorophenolic compounds, and soil bioremediation. They are also the cause of disease in commercially produced mushrooms. The species Trichoderma has not been clearly defined yet, despite being a very common fungus with an expanding number of applications. Therefore, we highlight the importance of the use of molecular techninques along with conventional methodologies based on morphological characters in order to achieve a "natural" taxonomic system for this group of fungi, as well as for any other complex group of fungi.

Production and antiproliferative activity of liposomes containing the antitumour drug chromomycin A3

In the present paper the production and characterization of liposomes are described as a specialized drug delivery system for chromomycin. Liposomes were prepared by the reverse phase evaporation technique followed by extrusion through polycarbonate filters; afterwards the vesicles were characterized in terms of dimensions, morphology and encapsulation efficacy. The aim of this work was to produce a drug delivery system able to reduce the toxicity problems related to the administration of this drug. The analysis of the in vitro antiproliferative activity on cultured human leukemic K562 cells demonstrated that ionic and neutral liposomes containing chromomycin are 1.5 and 7-fold more effective respectively as compared to the free drug. Based on these results and taking into account the increased solubility of the drug in this system, liposomes could represent a promising drug delivery system for use in the experimental therapy using chromomycin.

Urinary NMP22 in the management of superficial bladder tumours after transurethral resection

The aim of this study was to evaluate the clinical utility of the NMP22 test after transurethral resection of superficial transitional cell carcinoma of the bladder. The test was performed in 28 patients with histologically confirmed bladder tumours and in 41 patients who already had two consecutive negative cytological and cystoscopic results at least 3 months after TUR. In the first group the mean NMP22 value was 62.5 u/ml with a false negative rate of 18%. The specificity of the NMP22 test in 41 patients with a previous history of TCCB was 49%. No difference was detected between patients treated or not with intravesical chemotherapy. Despite its good sensitivity, the NMP22 test cannot be adopted as a routine tool in post-TUR surveillance of patients with superficial bladder cancer, due to its low specificity.

Methods for the determination of nitrite by high-performance liquid chromatography with electrochemical detection

A review on the use of high-performance liquid chromatography coupled with electrochemical detection (HPLC-ED) for the measurement of nitrite (NO2-) and nitrate (NO3-) is presented. HPLC-ED has been used for the determination of NO2- and NO3- in food, biological and environmental samples. Analysis of the current literature indicates that the measurement of NO2- and NO3- by the HPLC-ED procedure is more sensitive, selective and faster than methods based on UV absorption, photometry, fluorometry or chemiluminescence.

Myrosinase-generated isothiocyanate from glucosinolates: isolation, characterization and in vitro antiproliferative studies

Epidemiological and pharmacological studies have shown that colorectal cancer development could be reduced by consuming vegetables that contain glucosinolates. In view of this the effect of some glucosinolates and their isothiocyanate (ITC)-derived products on in vitro cell growth was studied. We report the isolation and characterization of ITCs derived from glucosinolates by using HPLC, GC-MS, and NMR techniques. The in vitro activity of ITCs on human erythroleukemic K562 cells has been investigated by using two alternative approaches: the in situ and pre-mix methods. No differences in antiproliferative activity were found comparing the effect of ITCs produced either of these methods. In the experimental conditions used, the production of ITCs from glucosinolates is almost quantitative as confirmed by HPLC or GC-MS analysis. The ITCs' inhibitory activity on K562 cells growth is particularly evident in the cases of ITCs derived from sinigrin, progoitrin, epi-progoitrin, glucotropaeolin and glucocheirolin. Finally, the antiproliferative activity of the ITCs obtained from glucoraphenin, taken as an example, was determined on other tumor cell lines with a different origin and hystotype. Considering the antiproliferative activity found for ITCs these compounds could be considered potentially responsible for the reduction of colorectal cancer associated with diets rich in cruciferous vegetables. Further studies will be aimed at the possible application of glucosinolate-derived products as chemopreventive cancer agents.

The degree of inhibition of dopaminergic neurons in the ventral tegmental area induced by selective serotonin reuptake inhibitors is a function of the density-power-spectrum of the interspike interval

Electrophysiological techniques and computational methods were used to study the effect of the selective serotonin reuptake inhibitors fluvoxamine, paroxetine and sertraline on the basal activity of dopamine neurons in the ventral tegmental area. Acute injection of fluvoxamine, paroxetine and sertraline (20-1280 microg/ kg, i.v.) caused a dose-dependent inhibition of some ventral tegmental area DA neurons but it did not affect the basal firing rate of other DA cells. A Fast-Fourier-Transformation based analysis of the basal activity of 32 ventral tegmental area DA neurons showed a positive correlation between the value of a functional operator (psi) equivalent to the density-power-spectrum of the signals and the degree of selective serotonin reuptake inhibitor-induced inhibition of ventral tegmental area DA cells. All ventral tegmental area DA neurons sampled were subdivided into two subclasses: (A) neurons with no changes in their basal firing rate and (B) neurons showing an approximately linear inhibitory effect in response to selective serotonin reuptake inhibitors. The neurons belonging to subclass A showed a more regular behavior of the interspike interval functions corresponding to lower values detected by the functional operator psi, whereas the neurons belonging to subclass B showed a less regular behavior of interspike interval functions corresponding to higher psi values detected by the same functional operator. Fluvoxamine, paroxetine and sertraline also caused a dose-dependent increase of the percentage of spikes occurring in bursts in neurons belonging to subclass A (low values of psi), whereas the mean basal firing rate of these cells was not affected. It is suggested that this difference in density-power-spectrum could reflect the asymmetry of serotonergic input to the ventral tegmental area DA neurons, and the differential effects of selective serotonin reuptake inhibitors on these neurons might depend on the characteristics of their basal firing mode.

[In-hospital mortality of elderly patients with myocardial infarct. Difference between the sexes]

The number of women who become ill and die from acute myocardial infarction (AMI) increases steadily with age. It is not yet clearly defined whether and why women suffer from a higher in-hospital mortality rate after AMI. In this study we evaluated the importance of the female sex as a risk factor for in-hospital mortality in elderly patients suffering from AMI. A retrospective study was performed in 724 patients (429 males, 295 females) aged > or = 65 years (mean age 74.9 +/- 6.3 years) consecutively admitted to San Giovanni Battista Hospital in Turin during the period 1988-1991 with validated primary discharge diagnosis of AMI. In-hospital mortality was significantly higher in females (34.6%) compared to males (25.6%, p > 0.01). After multivariate analysis female sex was not independent predictive for in-hospital death. Multivariate analysis was therefore repeated in the various sections of the history of AMI (anamnestic variables, including age and sex: physical signs on admission, ECG findings, laboratory tests, clinical progress, including complications and treatment) in order to identify the factors responsible for the higher mortality rate in women. These were found to be low hemoglobin values (< 12 g/dl) on admission, development of cardiac failure disorders and rhythm disturbances during hospitalization, and differences in therapeutic procedures. In spite of the absence of an independent unfavourable effect of female sex, elderly women with AMI have a higher in-hospital mortality rate. A more precarious state of health on admission, a peculiar susceptibility to severe complications during hospital-stay and differences in therapeutic procedures appear to be the factors responsible for this increased mortality rate in women.

A case-control study on lymphocytic subsets in elderly bearing a gastroenteric cancer

The aim of this work is to evaluate the differences in lymphocytic sub-classes between elderly patients with gastroenteric cancer and elderly patients with a non neoplastic disease. A group of 88 patients over 60, consecutively admitted to the III Division General Surgery for gastro-enteric cancer has been collected for the study, the control group consisted of 74 patients also over 60, consecutively admitted over the same period for benign abdominal diseases. In all patients the following data were measured: body mass index (BMI), white blood cells (WBC), total lymphocytes, total T lymphocytes (CD3+), helper T lymphocytes (CD4+), suppressor T lymphocytes (CD8+), CD4+/CD8+ ratio, B lymphocytes, CD5+ B lymphocytes, activated T lymphocytes (CD3+ HLA-DR+), CD4+ "naive" lymphocytes (CD4+ CD45 RA+), CD4+ "memory" lymphocytes (CD4+ CD45 RO+), NK lymphocytes (CD16+ 56+), red blood cells (RBC), total serum cholesterol, albumin, total serum proteins. The main lymphocytic subsets were on an average lower in the cancerous elderly group with respect to the non cancerous. As the tumour progressively increases in size (T), total lymphocytes significantly decrease, while CD4+ progressively decreases with nodal involvement (N). In the cancerous elderly, we found a lower immune response. The immune system appears to be less efficient also in association with tumor growth, especially when T and N get worse. The response of effector cells to the tumour seems not specific.

Biodegradable microparticles for sustained delivery of tetracycline to the periodontal pocket: formulatory and drug release studies

This paper describes the production and characterization of biodegradable microparticles containing tetracycline, designed for periodontal disease therapy. The influence of production parameters on microparticle characteristics and antibiotic release modality was studied. Microparticles were made by using different preparation procedures and different polyesters, namely poly(L-lactide), [L-PLA] poly(DL-lactide), [DL-PLA] and poly(DL-lactide-co-glycolide) 50:50, [DL-PLG]. A double emulsion preparation method together with a concentrated salt solution as external phase gave the best results in terms of tetracycline incorporation efficacy. In vitro release experiments demonstrated that tetracycline is slowly and appropriately released from microparticles. Release kinetics were found to be influenced by the type of polymer utilized for microparticle production. In vitro experiments, simulating in vivo conditions were carried out for up to 30 days. Only DL-PLG microparticles showed significant changes in their morphology, whereas L-PLA and DL-PLA were found almost intact after the same period of time.

Lignin biodegradation by the ascomycete Chrysonilia sitophila

The lignin biodegradation process has an important role in the carbon cycle of the biosphere. The study of this natural process has developed mainly with the use of basidiomycetes in laboratory investigations. This has been a logical approach since most of the microorganisms involved in lignocellulosic degradation belong to this class of fungi. However, other microorganisms such as ascomycetes and also some bacteria, are involved in the lignin decaying process. This work focuses on lignin biodegradation by a microorganism belonging to the ascomycete class, Chrysonilia sitophila. Lignin peroxidase production and characterization, mechanisms of lignin degradation (lignin model compounds and lignin in wood matrix) and biosynthesis of veratryl alcohol are outstanding. Applications of C. sitophila for effluent treatment, wood biodegradation and single-cell protein production are also discussed.

Stability and chemical modification of xylanase from Aspergillus sp. (2M1 strain)

The 2M1 strain of Aspergillus sp., which showed high extracellular xylanolytic activities in a pre-screening, was studied. Oat-spelt, birch, eucalyptus and pine xylans were used as xylanolytic inductors. The following activities were found at 50 degrees C in the presence of 1% xylan: 120 units/ml (oat-spelt xylan), 132 units/ml (birch xylan), 107 units/ml (eucalyptus xylan), 67 units/ml (pine xylan) and 137 units/ml (larch-wood xylan). Xylanase induced by pine xylan exhibited a higher stability than those induced by the other xylans. The stability was improved by addition of glycerol. In the crude extract, reagents which were found to affect xylanase activity were 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide for amidation of carboxylic groups and N-bromosuccinimide at a concentration of 0.5 mM for indole oxidation. Methylene Blue, butane-2,3-dione, N-acetylimidazole, chloramine-T and iodoacetate had little effect on the enzyme activity (more than 97% of the original activity remained).

T1-T2-T3 glottic tumors: fifteen years experience with CO2 laser

This research aims at reporting the results of endoscopic treatment of glottic carcinomas by CO2 laser. The cases cited concern 516 patients with glottic T1-T2-T3 carcinomas. The patients have been divided into 5 groups: a) T1a: 194 patients with monolateral carcinoma involving the true vocal cord who underwent simple cordectomy; b) T2a: 104 patients with monolateral cordal carcinoma involving the ventricle and the false cord; c) T1b: 127 cases of monolateral or bilateral carcinoma involving the anterior commissure; d) these patients underwent bilateral cordectomy; T2b: 54 cases of monolateral or bilateral carcinomas involving the anterior commissure and extending to the hypoglottic or supraglottic region; in these patients a bilateral extended cordectomy was performed; e) T3: 37 selected cases of monolateral or bilateral cordal carcinoma with fixed vocal cord, fixity was due to the substantial size of the tumor or to the infiltration of the paraglottic space; these patients underwent a monolateral or bilateral extended cordectomy. The following are the results at 5 years: group a: overall observed survival rate (OSR) was 79% and the adjusted survival rate (ASR) 94.5%; group b: OSR 67% and ASR 77%; group c: OSR 88.4% and ASR 96.5%; group d: OSR 82% and ASR 90%; group e: OSR 55% and ASR 67%. The above data are evidence of the fact that our surgical techniques offer similar or better advantages in terms of survival rate compared to the traditional procedures. It must be noted that endoscopic surgery of glottic tumors carried out by CO2 laser offers relevant benefits when compared with traditional surgery: i) rapidity of operation and reduced surgical trauma; ii) the possibility of avoiding tracheotomy; iii) the respect of the integrity of the cartilaginous skeleton; iv) short postoperative course and low incidence of complication; v) better functional results; vi) a shorter stay in hospital with positive psychological effects on the patients and lower social costs.

Gelatin microspheres: influence of preparation parameters and thermal treatment on chemico-physical and biopharmaceutical properties

The aim of this paper was to investigate the influence of preparation parameters on gelatin microspheres production, chemico-physical characteristics and drug encapsulation. In particular, we focussed our attention on the manufacturing parameters such as amount of polymer, stirring speed, presence and concentration of surfactants. As model drugs, TAPP-Br, clonidine hydrochloride and bromocriptine mesylate were chosen in order to compare their encapsulation and release characteristics with microspheres. In the second part of this work, a study of the influence of thermal treatment on the microspheres is reported, performed with the aim to possibly modify gelatin dissolution and drug release. In particular, the effect of this treatment was evaluated on microsphere characteristics such as swelling, porosity and dissolution, and finally on the release profiles of the encapsulated drugs.

Experimental study on protein transmission through the human muscle fascia: preliminary results and application theory in lymphedema

The presence of proteins (albumin and globulins) in lymphedematous tissue not only gives rise to colloidosmotic pressure but also produces an electrostatic charge endowing the proteins with individual features and different migration rates. The working hypothesis of the experimental study is to transfer lymph proteins from the upper fascia accumulation area to a subfascial drainage area by subjecting them to an adequate difference in potential. A double chamber, variable volume system with separation wall able to contain a 1 cm square of muscle fascia, was designed and built; the aim of the apparatus was to reproduce the subcutaneus zone separated by the fascia interposition, from the muscle-vascular zone. At the system was applied a variable electric field in six different experiments: 4 using porous synthetic membranes and 2 using human muscle fascia.