Arthrobacter sp. Inoculation Improves Cactus Pear Growth, Quality of Fruits, and Nutraceutical Properties of Cladodes.

A study was undertaken to determine the effects of a strain of Arthrobacter sp., a Plant Growth-Promoting Bacteria (PGPB), on plant phenology and qualitative composition of Opuntia ficus-indica (L.) Mill. fruits and cladodes. The strain was inoculated in soil, and its effects on cactus pear plants were detected and compared to nontreated plants. Compared to the latter, the treatment with bacteria promoted an earlier plant sprouting (2 months before the control) and fruitification, ameliorating fruit quality (i.e., improved fresh and dry weight: + 24% and + 26%, respectively, increased total solid content by 30% and polyphenols concentrations by 22%). The quality and quantity of monosaccharides of cladodes were also increased by Arthrobacter sp. with a positive effect on their nutraceutical value. In summer, the mean values of xylose, arabinose, and mannose were significantly higher in treated compared to not treated plants (+ 3.54; + 7.04; + 4.76 mg/kg d.w. respectively). A similar trend was observed in autumn, when the cladodes of inoculated plants had higher contents, i.e., 33% xylose, 65% arabinose, and 40% mannose, respect to the controls. In conclusion, Arthrobacter sp. plays a role in the improvement of nutritional and nutraceutical properties of cactus pear plants due to its capabilities to promote plant growth. Therefore, these results open new perspectives in PGPB application in the agro-farming system as alternative strategy to improve cactus pear growth, yield, and cladodes quality, being the latter the main by-product to be utilized for additional industrial uses.

The impact of first wave of COVID-19 on the nursing-sensitive and rehabilitation outcomes of patients undergoing hip fracture surgery: a single centre retrospective cohort study.

BACKGROUND: During the COVID-19 pandemic, the care of hip fracture patients remains a clinical priority. To date, there is limited empirical knowledge about the impact of pandemic on the care of patients surgically treated for hip fracture, affected or not by COVID-19. OBJECTIVE: To investigate the effects of the COVID-19 pandemic on the nursing-sensitive and rehabilitation outcomes of frail patients undergoing hip fracture surgery. METHODS: A retrospective cohort study was conducted in an Italian Orthopaedic Research Institute. All patients aged ≥ 65 years admitted with fragility hip fractures between 1st March and 30th June in 2019 (group PP: pre-pandemic) and in the same period in 2020 (group P: pandemic), were compared. In the P group, COVID-19 positive patients were excluded due to the presence of a specific treatment pathway. Data on patient demographics and baseline characteristics, and peri-operative care factors were obtained from the Institute's computer-based patient-record system. The primary outcome was the incidence of any stage hospital-acquired pressure ulcers (PUs). The secondary outcome was time to first static verticalization and to first ambulation. RESULTS: Three-hundred and sixty patients were included in the study, which comprised 108 patients in PP group and 252 patients in P group. Overall PUs incidence was significantly higher in the P-group (21.8%) than in the PP-group (10.2%) (p = 0.009). Specifically, the incidence of sacral PUs was significantly lower in P-group (38.1%) vs PP-group (91%) (p = 0.004); on the contrary, the incidence of PUs localized to the heels or other body sites were significantly higher in P-group (30.9% and 30.9%, respectively) vs PP-group (0% and 9%, respectively) (p = 0.004). No significant between groups differences were found for all the secondary outcomes. CONCLUSION: In the pandemic period, nursing and rehabilitation care provided to patients with fragility hip fracture maintained high standards comparable to the pre-pandemic period. The increase in PUs incidence in the pandemic period was probably due to the older age of the patients admitted to hospital. The qualitative evaluation of the care administered and the emotional impact of the pandemic on the patients are very interesting topic which would deserve further investigation.

Italian guidelines for the surgical management of enteral stomas in adults.

BACKGROUND: Worldwide, stomas represent a medical and social problem. Data from the literature on stoma management are extensive but not homogeneous. In Italy, no guidelines exist for this topic. Thus, clear and comprehensive clinical guidelines based on evidence-based data and best practice are need. In 2018, the Multidisciplinary Italian Study group for STOmas, called MISSTO, was founded. The aim was to elaborate guidelines for practice management of enteral and urinary stomas in adults. METHODS: A systematic review of the literature was performed using PubMed, National Guideline Clearinghouse, and other databases. The research included guidelines, systematic reviews, meta-analyses, randomized clinical trials, cohort studies, and case reports. Five main topics were identified: "stoma preparation", "stoma creation", "stoma complications", "stoma care", and "stoma reversal". The systematic review was performed for each topic, and studies were evaluated according to the GRADE system, AGREE II tool. RESULTS: Recommendations were elaborated in the form of statements with an established grade of recommendation for each statement. For low levels of scientific evidence statements, a consensus conference composed of expert members of the major Italian scientific societies in the field of stoma management and care was held. After discussing, correcting, validating, or eliminating the statements by the experts, the final version of the guidelines was elaborated and prepared for publication. This manuscript is focused on statements on the surgical management of enteral stomas. CONCLUSIONS: These guidelines are the first Italian guidelines on multidisciplinary management of enteral stomas with the aim of assisting surgeons during stoma management and care.

Effects of treated industrial wastewaters and temperatures on growth and enzymatic activities of duckweed (Lemna minor L.).

The efficacy of the removal of contaminants from wastewater depends on physico-chemical properties of pollutants and the efficiency of treatment plant. Sometimes, low amounts of toxic compounds can be still present in the treated sewage. In this work we considered the effects of contaminant residues in treated wastewaters and of temperatures on Lemna minor L. Treated effluent waters were collected, analyzed and used as duckweed growth medium. In order to better understand the effects of micropollutants and seasonal variation, the plants were grown under ambient conditions for seven days in summer and winter. Relative growth rate, pigments and phenolic compounds concentrations were determined, as well as the activities of catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (G-POD) and polyphenol oxidase (PPO). The pollutant concentrations varied in the two seasons, depending on the industrial and municipal activities and efficiency of treatments. Treated waters contained heavy metals, nitrogenous and phosphorus compounds, surfactants and hydrocarbons. Compared to the control, duckweed growth of treated plants decreased by 25% in summer, while in the winter due to the lower temperatures and the presence of pollutants was completely impeded. The amounts of photosynthetic pigments of treated plants were not significantly affected in the summer, while they were higher than the control in the winter when the effluent had a high nitrogen amount. High CAT activity was registered in both seasons. Treated plants had significantly lower APX activity in the summer (53%) and winter (59%) respect to the controls. The observed inhibition of the peroxidase activities in the exposed plants, confirms the controversy existing in the literature about the variability of enzymatic response in stress condition.

Role of transglutaminase 2 in quercetin-induced differentiation of B16-F10 murine melanoma cells.

Flavonoids belong to the class of plant polyphenolic compounds with over 6,000 individual structures known. These phytochemicals have attracted the interest of the scientists, because they possess a remarkable spectrum of biological activities, such as antiallergic, antiinflammatory, antioxidant, antimutagenic and anticarcinogenic. In this work, we compared the anticancer potential of two flavonoids, quercetin and pelargonidin, on highly metastatic B16-F10 melanoma murine cells. We have evaluated different parameters related to cell proliferation and differentiation, such as cell number, toxicity, intracellular content of polyamines and transglutaminase (TG, EC 2.3.2.13) activity. The higher inhibition of tumor cell growth, with respect to control, was obtained with quercetin cell treatment, i.e. 32% reduction after 48 h and 39% reduction after 72 h of incubation (P < 0.001). In parallel, quercetin-treated cells showed a similar decrease in polyamine content. TG activity was fourfold increased, with respect to control, after 48 h and twofold increased after 72 h (P < 0.001). Pelargonidin treatment did not show significant antiproliferative effects and any increase in TG activity. Proteomic approach was used to investigate changes in protein expression profiles in tumor cells following quercetin treatment. Changes in expression of 60 proteins were detected, i.e. 8 proteins were down-regulated, 35 up-regulated, 11 "de novo" synthetized proteins and 6 suppressed proteins were present in treated cells. A 80 kDa spot, identified as TG type 2 by Western blot analysis, presented a fourfold increase in intensity, confirming the key role played by TG in the induction of cancer cell differentiation.

Adjuvant and neo-adjuvant chemotherapy for Ewing's sarcoma family tumors and osteosarcoma of the extremity: further outcome for patients event-free survivors 5 years from the beginning of treatment.

BACKGROUND: In 326 patients with Ewing's sarcoma family tumor (ESFT) and 628 extremity osteosarcoma (OS) treated with adjuvant and neo-adjuvant chemotherapy and event-free survivors 5 years from the beginning of treatment we evaluated outcome in the following years. Post 5-year follow-up for these patients was 9.7 years (5.5-29 years). PATIENTS AND METHODS: Adverse events observed after 5-year follow-up were 73 (7.6%): 38 late relapses, nine leukemia, 14 second solid tumor, seven radioinduced sarcoma, three severe adriamycin-related cardiomyopathy, one suicide and one death by car crash. RESULTS: Of the patients who developed late events, 16 (22.5%) are alive and event free after 8 years from the last treatment (2-22 years). CONCLUSION: We conclude that the high rate of late adverse events after 5 years in patients with OS and ESFT is noteworthy and indicates that these patients should be followed for >5 years.

Ewing's sarcoma family tumours. Differences in clinicopathological characteristics at presentation between localised and metastatic tumours.

Despite local treatment with systemic chemotherapy in Ewing's sarcoma family tumours (ESFT), patients with detectable metastases at presentation have a markedly worse prognosis than those with apparently localised disease. We investigated the clinical, pathological and laboratory differences in 888 patients with ESFT, 702 with localised disease and 186 with overt metastases at presentation, seen at our institution between 1983 and 2006. Multivariate analyses showed that location in the pelvis, a high level of serum lactic dehydrogenase, the presence of fever and a short interval between the onset of symptoms and diagnosis were indicative of metastatic disease. The rate of overt metastases at presentation was 10% without these four risk factors, 22.7% with one, 31.4% with two, and 50% for those with three or four factors. We concluded that in ESFT the site, the serum level of lactic dehydrogenase, fever, and the interval between the onset of symptoms and diagnosis are indicators of tumours having a particularly aggressive metastatic behaviour.

Treatment and prognosis for synchronous multifocal osteosarcoma in 42 patients.

Between 1986 and 2002, 42 patients with synchronous multifocal osteosarcoma were treated with two different protocols of neoadjuvant chemotherapy. When feasible, the primary and secondary tumours were excised as a combined procedure. After initial chemotherapy 26 patients were excluded from simultaneous excision of all their secondary bone lesions as their disease was too advanced. In 12 patients only isolated excision of the primary lesion was possible. For 16 patients simultaneous operations were conducted to excise the primary and secondary lesions. This involved two supplementary sites in 15 patients and four additional sites in one patient. Of these, 15 attained remission but 12 relapsed and died (11 within two years). Three patients remained disease-free at five, six and 17 years. The histological response to pre-operative chemotherapy of the primary and secondary lesions was concordant in 13 of the 16 patients who underwent simultaneous operations at more than one site. The prognosis for synchronous multifocal osteosarcoma remains poor despite combined chemotherapy and surgery. The homogeneous histological responses in a large proportion of the primary and secondary lesions implies that synchronous multifocal osteosarcoma tumours are not multicentric in origin, but probably represent bone-to-bone metastases from a single tumour.

Long-term outcome for patients with nonmetastatic osteosarcoma of the extremity treated at the istituto ortopedico rizzoli according to the istituto ortopedico rizzoli/osteosarcoma-2 protocol: an updated report.

PURPOSE: To provide an estimate of long-term prognosis for patients with osteosarcoma of the extremity treated in a single institution with neoadjuvant chemotherapy and observed for at least 10 years. PATIENTS AND METHODS: Patients with nonmetastatic osteosarcoma of the extremity were preoperatively treated with high-dose methotrexate, cisplatin, and doxorubicin (ADM). Postoperatively, good responders (90% or more tumor necrosis) received the same three drugs used before surgery, whereas poor responders (less than 90% tumor necrosis) received ifosfamide and etoposide in addition to those three drugs. RESULTS: For the 164 patients who entered the study between September 1986 and December 1989, surgery was a limb salvage in 136 cases (82%) and a good histologic response was observed in 117 patients (71%). At a follow-up ranging from 10 to 13 years (median, 11.5 years), 101 patients (61%) remained continuously free of disease, 61 relapsed, and two died of ADM-induced cardiotoxicity. There were no differences in prognosis between good and poor responding patients. ADM-induced cardiotoxicity (six patients), male infertility (10 of the 12 assessable patients), and second malignancies (seven patients) were the major complications of chemotherapy. Despite the large number of limb salvages performed, only four local recurrences (2.4%) were registered. CONCLUSION: With an aggressive neoadjuvant chemotherapy, it is possible to cure more than 60% of patients with nonmetastatic osteosarcoma of the extremity and amputation may be avoided in more than 80% of them. Because local or systemic relapses, myocardiopathies, and second malignancies are possible even 5 years or more after the beginning of treatment, a long-term follow-up is recommended for these patients.

Prognostic factors in nonmetastatic Ewing's sarcoma of bone treated with adjuvant chemotherapy: analysis of 359 patients at the Istituto Ortopedico Rizzoli.

PURPOSE: The identification of prognostic factors in patients with nonmetastatic Ewing's sarcoma could allow the use of risk-adapted therapeutic strategies of treatment. PATIENTS AND METHODS: Data on 359 patients with nonmetastatic Ewing's sarcoma of bone treated at a single institution between January 1979 and April 1995 were retrospectively considered. The influence of clinical, hematologic, therapeutic, and histologic parameters on event-free survival was assessed. RESULTS: By univariate analysis, the following features were found to be associated with a poor prognosis: male sex (P <.02), age older than 12 years (P <.006), fever (P <.0001), anemia (P <.0025), high serum lactate dehydrogenase (LDH) level (P <.0001), axial location (P <.04), radiation therapy only for local control (P <.009), type of chemotherapy regimen (P <.0001), and poor chemotherapy-induced necrosis (P <.001). After multivariate analysis, the adverse independent prognostic factors were male sex (P <.04), age older than 12 years (P <.001), fever (P <.0002), anemia (P <.02), high serum LDH level (P <.0003), axial location (P <.02), and type of chemotherapy regimen (P <.0003). When the multivariate analysis was restricted to surgically treated patients, the adverse independent prognostic factors were poor chemotherapy-induced necrosis (P <.0001), fever (P <.015), anemia (P <.02), and high serum LDH level (P <.025). CONCLUSION: The prognosis in cases of nonmetastatic Ewing's sarcoma is influenced by many different clinical and hematologic variables, all of which are to be considered when patients are being stratified according to the risk of relapse. In surgically treated patients, the most important prognostic factor is chemotherapy-induced necrosis.

Neoadjuvant chemotherapy for peripheral malignant neuroectodermal tumor of bone: recent experience at the istituto rizzoli.

PURPOSE: The results achieved in 44 patients with nonmetastatic peripheral neuroectodermal tumor (PNET) of bone treated with neoadjuvant chemotherapy are reported. PATIENTS AND METHODS: A six-drug regimen of chemotherapy (vincristine, doxorubicin, dactinomycin, cyclophosphamide, ifosfamide, and etoposide) was administered to all patients. Local treatment consisted of surgery in 20 patients, surgery followed by radiotherapy in 13, and radiotherapy only in 11. RESULTS: At a mean follow-up of 4.5 years (range, 2 to 7 years), 23 patients (52%) remain event-free, 20 have relapsed (45%), and one has died of chemotherapy-related toxicity. The 5-year event-free survival and overall survival were 54.2% and 62.7%, respectively. To assess the prognostic significance of neural differentiation in the family of Ewing's sarcoma, these results have been compared with the outcomes of 138 concomitant patients with typical Ewing's sarcoma (TES) who were treated according to the same protocol. Of these, 103 (75%) remained continuously event-free, 34 (24%) relapsed, and one died of chemotherapy-related toxicity. It follows that PNET patients treated with this chemotherapy regimen have a significantly worse prognosis than typical ES patients (5-year event-free survival, 54.2% v 70.6%, P <.012; 5-year overall survival, 62.7% v 78.3%, P <.002). CONCLUSION: The authors conclude that studies into new adjuvant therapy for Ewing's sarcoma modulated according to risk of relapse should also consider neural differentiation as a risk factor.

Long-term outcome for patients with non-metastatic Ewing's sarcoma treated with adjuvant and neoadjuvant chemotherapies. 402 patients treated at Rizzoli between 1972 and 1992.

We evaluated the long-term results obtained in 402 patients with non-metastatic Ewing's sarcoma (ES) of the bone treated in a single institution with adjuvant and neoadjuvant chemotherapies between 1972 and 1992. Multivariate analyses showed male gender, age older than 14 years, high serum lactate dehydrogenase (LDH) level, axial location of the tumour, use of radiotherapy alone as a local treatment, and poor histological response to chemotherapy, to be independent, adverse prognostic factors for event-free survival (EFS). At a mean follow-up of about 18 years (10-30 years), 177 patients (44.0%) remained continuously free of disease, 2 died of doxorubicin-induced cardiotoxicity and 8 developed a second neoplasm (5 died, and 3 are alive and free of disease). 215 patients relapsed with metastases and/or local recurrence: 14 are alive and free of disease, 1 is alive with uncontrolled disease, and 200 died. The overall survival (OS) at real follow-ups of 5-, 10-, 15- and 20-years was 57.2, 49.3, 44.9 and 38.4%, respectively. We conclude that since local or systemic relapses, treatment-complications and second malignancies are more common after 5 years or more from the beginning of treatment; a long-term follow-up is mandatory for patients with ES.

Pattern of relapse in patients with osteosarcoma of the extremities treated with neoadjuvant chemotherapy.

570 patients with osteosarcoma of the extremities were treated with five different protocols of neoadjuvant chemotherapy at Rizzoli Institute between 1983 and 1995. Surgery consisted of limb salvage in 83% rotation plasty in 5% and amputation in 12%. The 5-year event-free survival (EFS) was 60% which varied according to the protocol followed, ranging from 47.6% to 66.4%. 234 patients relapsed. The pattern of relapse was analysed. The mean relapse time was 23.8 months (range: 2-96). The first site of systemic relapse was the lung in 88% (32% of these had less than three pulmonary metastases and 68% three or more), bone in 9%, lung and bone in 2% and other sites in 3%. The relapse time and the number of pulmonary metastases were strictly correlated with the efficacy of the protocol of chemotherapy used. Patients treated with the three protocols that gave a 5-year EFS of more than 60% relapsed later and had fewer pulmonary lesions than patients treated with the two protocols that gave a 5-year EFS of 47.6% and 52.5%. The rate of local recurrence was relatively low (6%). This was not correlated with the protocol or the type of surgery used: limb salvage (6.4%), rotation plasty or amputation (4.1%). However, the rate of local recurrence was very high (21.9%) in the few patients (7%) that had less than wide surgical margins. We conclude that for patients with osteosarcoma of the extremities treated with neoadjuvant chemotherapy: (a) the pattern of systemic relapse changes according to the efficacy of the protocol of chemotherapy used. This should be always considered when evaluating the preliminary results of new studies as well as in defining the time of follow-up; (b) limb salvage procedures are safe and do not jeopardise the outcome of the patient, provided that wide surgical margins are achieved.

Neoadjuvant chemotherapy for osteosarcoma of the extremity: long-term results of the Rizzoli's 4th protocol.

From January 1993 to March 1995, 162 patients with osteosarcoma of extremities were treated according to the IOR/OS-4 protocol. 133 patients had localised disease, while 29 had metastases at diagnosis. These last patients were simultaneously operated upon for their primary and metastatic lesions. Chemotherapy consisted preoperatively of two cycles of high dose methotrexate (HDMTX) and one cycle each of cisplatin (CDP)-doxorubicin (ADM), CDP/ifosfamide (IFO) and IFO/ADM. After surgery, patients were treated with the aforementioned drugs used as single agents. The mean follow-up of all patients was 6.5 years (5.5-8 years). Surgery was a limb salvage in 94% of cases, and the 5-year event-free survival (EFS) and overall survival (OS) rates were 56 and 71% for patients with localised disease, and 17 and 24% for patients with metastases at diagnosis. These results did not differ from those achieved in our previous study (IOR/OS-3) in which IFO was used only postoperatively in poor responders.

Neoadjuvant chemotherapy for Ewing's tumour of bone: recent experience at the Rizzoli Orthopaedic Institute.

The results achieved in 157 patients with non-metastatic Ewing's sarcoma of the bone treated at a single institution between 1991 and 1997 according to a new protocol (REN-3) are reported. Induction chemotherapy consisted of two cycles of 'VAC': vincristine (V), doxorubicin (A), cyclophosphamide (C) alternated with one cycle of 'VIAc': V, ifosfamide (I), actinomycin (Ac). After local treatment, patients received three more cycles of VAC, two of VIAc, three cycles of I plus etoposide (E) and two cycles with V, C and Ac. Local treatment was surgery in 53% of patients, surgery+radiotherapy in 25% and radiotherapy only in 22%. With a follow-up ranging between 4 and 10 years (mean: 7 years), 110 patients (70%) remained continuously event-free, 2 patients died of toxicity and 45 patients relapsed: 33 due to metastases and 12 due to local recurrence always associated with metastases. The 5-year event-free survival (EFS) and overall survival (OS) were 71.0 and 76.5% respectively. These results are significantly better that the ones achieved in our previous three studies in which a three-drug VAC regimen (REA-1), and 4-drug VACAc regimen (REA-2 and REN-1) was used, and in our most recent study (REN-2) which was based on a six-drug regimen as in the present study, but where I and Ac were used only after the local treatment. However, since REN-3 surgery was used in a significantly larger number of patients, we cannot say whether the better outcome of this study was due to the use of a six-drug regimen with an early delivery of ifosfamide and actinomycin, or to the wider use of surgery as local treatment or both.

Gamma-aminobutyric acid and the high pressure neurological syndrome.

Sodium valproate, nipecotic acid, diaminobutyric acid (DABA) and beta-alanine are drugs which enhance transmission mediated by gamma-aminobutyric acid (GABA) by a variety of mechanisms. They were used to study the role of GABA in the high pressure neurological syndrome (HPNS) in the rat. Sodium valproate, nipecotic acid and DABA reduced the increase in slow waves seen in the electroencephalogram (EEG) of control rats at pressures above 10-20 ATA; however, only sodium valproate had a beneficial effect on the behavioural signs of the high pressure neurological syndrome (tremor, myoclonus and convulsions). Sodium valproate is also thought to decrease neurotransmission produced by excitatory amino acids; thus, these results suggest that GABA is not one of the major neurotransmitters involved in all aspects of the high pressure neurological syndrome and that changes in excitatory neurotransmission may affect the behavioural signs.

Continuous administration of the glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxylate produces striatal lesion.

This study examined the effects of chronic intrastriatal infusion of L-trans-pyrrolidine-2,4-dicarboxylate (PDC), a selective competitive inhibitor of high affinity glutamate transport systems, via osmotic minipumps in rats. Injection of PDC at the rate of 25 nmol/h for 14 days caused striatal lesion. Histological evaluation on frontal striatal sections showed that the lesion was circumscribed to a circular area showing a dramatic neuronal loss accompanied by gliosis and representing 30% of the whole striatal surface at the level of the injection site. A total loss of neurons expressing glutamate decarboxylase (GAD67), enkephalin or substance P mRNA was observed on a similar circular area, suggesting degeneration of the two populations of striatal efferent neurons. In the whole striatum outside the region devoided of hybridization signal, a selective 27% decrease in enkephalin mRNA expression occurred, suggesting a higher sensitivity of enkephalin neurons versus substance P neurons to glutamate uptake-mediated alterations. Injection of PDC at the rate of 25 nmol/h for 3 days produced striatal lesion of similar extent. In contrast, PDC at the rate of 5 nmol/h did not produce neuronal damage when administered over 14 days. This study provides new in vivo evidence that defective glutamate transport is one of the critical conditions that may give rise to toxicity of an endogenous transmitter system in the striatum, and may underlie neuronal death in neurodegenerative diseases.

Effects of high pressures of various gas mixtures on rat striatal dopamine detected in vivo by voltammetry.

This work was performed to study the effect of pressure of various gas breathing mixtures on dopaminergic activity in the striatum by in vivo differential pulse voltammetry using carbon multifiber electrodes chronically implanted in 23 freely moving rats. Compression (0.5 bar/min) in a helium-oxygen mixture induced an increase in striatal extracellular dopamine (DA) beginning at 10-20 bars and reaching 32% above precompression levels when arriving at 90 bars (n = 9). To demonstrate that this increase is dopaminergic, nine rats with right nigrostriatal pathway 6-hydroxydopamine lesions were compressed in the same conditions. In this case, the increase in DA did not occur in the right caudate nucleus but was recorded in the intact left caudate nucleus. To study the effects on DA increase of narcotic gases, which are known to reduce some high-pressure nervous syndrome symptoms, eight and six rats were compressed in helium-nitrogen-oxygen and hydrogen-helium-oxygen mixtures, respectively. They produced similar changes in striatal DA level in the same pressure range (23 and 20% increase, respectively, at the end of the compression). Consequently, the increase in striatal DA seems independent of the nature of the breathing mixture and seems related to the increase of pressure. The origin of this increase could be a pressure effect at the pre- or postsynaptic level.

Effect of helium-oxygen pressure on dopamine detected in vivo in the striatum of hamsters.

Free-moving hamsters chronically implanted in the striatum with carbon multifiber electrodes selective to dopamine were compressed in a helium-oxygen breathing mixture to 81 bars. Under these conditions, there was an increase in the electrochemical responses recorded from the carbon electrode by differential pulse voltammetry, which occurred during the compression and disappeared when the animals returned to the surface. This change was related to an increase in extracellular dopamine levels induced by the increase in pressure of the helium-oxygen mixture.

Electrochemical detection of dopamine release in the striatum of freely moving hamsters.

It was proposed to characterize the electrochemical signal recorded with a multifibre carbon electrode chronically implanted in the striatum of freely moving hamsters when the electrode potential was increased from-175 mV to +325 mV. Both in vitro calibration in standard solutions of oxidative molecules and in vivo pharmacological studies were used for this purpose. Results show that after an appropriate electrochemical treatment of the electrode in vitro the oxidation of dopamine (DA) produces a characteristic signal, whereas standard solutions of DOPAC and ascorbic acid produce no response. The electrochemical response recorded in vivo from the striatum of freely moving hamsters when the potential of the electrode is raised from-175 mV to +325 mV seems to correspond to the in vitro response to DA. This in vivo response diminished considerably following the destruction of the nigro-striatal dopaminergic neurones by means of an intranigral injection of 6-hydroxydopamine, while the striatal levels of ascorbic acid are not affected by the lesion. The administration of both amphetamine (3 mg/kg, i.p.) and the inhibitor of monoamine oxidases, pargyline (90 mg/kg i.p.), enhances the amplitude of the electrochemical signal. These results suggest that the electrochemical response recorded with our device in the striatum of the freely moving hamster corresponds to the oxidation of DA and not that of its metabolite DOPAC. Ascorbic acid is also very unlikely to contribute to the signal since the dopaminergic lesion does not alter the striatal level of this acid and since pargyline increases the amplitude of the signal.