The International Consortium on Primary Graft Dysfunction: Redefining Clinical Risk Factors in the Contemporary Era of Heart Transplantation

BACKGROUND

Primary Graft Dysfunction (PGD) is the leading cause of morbidity and mortality early after heart transplant (HT). The International Consortium on PGD is a multicenter collaboration dedicated to identifying the clinical risk factors for PGD in the contemporary era of HT. The objectives of the current report were to 1) assess the incidence of severe PGD in an international cohort, 2) evaluate the performance of the most validated PGD risk tool, the RADIAL score, in a contemporary cohort, and 3) redefine clinical risk factors for severe PGD in the current era of HT.

METHODS

This is a retrospective, observational study of consecutive adult HT recipients between 2010 and 2020 in 10 centers in the United States, Canada, and Europe. Patients with severe PGD were compared to those without severe PGD (comprising those with no, mild and moderate PGD). The RADIAL score was calculated for each transplant recipient. The discriminatory power of the RADIAL score was evaluated using receiver operating characteristic (ROC) analysis and its calibration was assessed by plotting the percentage of PGD predicted versus observed. To identify clinical risk factors associated with severe PGD, we performed multivariable mixed-effects logistic regression modeling to account for among-center variability.

RESULTS

A total of 2,746 patients have been enrolled in the registry to date, including 2,015 (73.4%) from North America, and 731 (26.6%) from Europe. 215 participants (7.8%) met the criteria for severe PGD. There was an increase in the incidence of severe PGD over the study period (p-value for trend by difference sign test = 0.004). The Kaplan Meier estimate for 1-year survival was 75.7% [95%CI 69.4-80.9%] in patients with severe PGD as compared to 94.4% [95% CI 93.5-95.2%] in those without severe PGD (log-rank p-value <0.001). The RADIAL score performed poorly in our contemporary cohort and was not associated with severe PGD with an AUC of 0.53 (95%CI 0.48-0.58). In the multivariable regression model, acute preoperative dialysis (OR 2.41, 95% CI 1.31 - 4.43), durable LVAD support (OR 1.77, 95% CI 1.13 - 2.77), and total ischemic time (OR 1.20 for each additional hour, 95% CI 1.02 - 1.41) were associated with an increased risk of severe PGD.

CONCLUSIONS

Our consortium has identified an increasing incidence of PGD in the modern transplant era. We identified contemporary risk factors for this early post-transplant complication, which confers a high mortality risk. These results may enable the identification of patients at high risk for developing severe PGD in order to inform peri-transplant donor and recipient management practices.

Clinical profile and in-hospital outcome of patients supported by intra-aortic balloon pump in the clinical setting of cardiogenic shock according to aetiology

Background

Despite controversial evidence, intra-aortic balloon pump (IABP) is still the most used temporary mechanical support in cardiogenic shock (CS), as a bridge to recovery or to more advanced mechanical support and/or heart transplantation [1]. Indeed, the available evidence, which is mainly restricted to the context of acute coronary syndromes (ACS) and is limited by the variability of CS definitions, shows no benefit in terms of mortality [2]. Randomized controlled trials on IABP in the setting of non-ACS CS are still missing. As a result, European guidelines do not recommend the routine use of IABP, which may be considered in refractory CS [3].

Purpose

The aim of our study was to analyse the use of IABP in the context of CS, providing insights into its indications, outcomes, and complications in relation to the aetiology (ACS vs non-ACS) of CS.

Methods

We retrospectively enrolled all consecutive adult patients receiving IABP for refractory CS at our tertiary referral Hospital between 2009 and 2018, and analysed data focusing on in-hospital outcomes, including death, recovery, heart transplantation, and escalation to more advanced mechanical support such as venoarterial extracorporeal membrane oxygenation (VA-ECMO) or left ventricular assist device (LVAD), and on IABP-related complications.

Results

403 patients received IABP, 75.2% (n=303) for ACS CS and 24.8% (n=100) for non-ACS CS. With respect to ACS patients, non-ACS patients were younger (age 59±18.3 vs 73.1±12.6 years old, p&lt;0.001), had a lower left ventricular ejection fraction (LVEF) [25% (IR 18–35%) vs 38% (IR 25–45%), p&lt;0.001], were supported by IABP for longer time [6 (IR 2–18) vs 2 (IR 1–4) days, p&lt;0.001], required more use of inotropes/vasoconstrictors [80.0% (n=80) vs 33.8% (n=102), p&lt;0.001], and needed more often escalation to VA-ECMO [23.0% (n=23) vs 1.3% (n=4), p&lt;0.001]. Non-ACS patients showed higher in-hospital mortality than ACS patients [46.0% (n=46) vs 33.9% (n=103), p=0.042]. Non-ACS patients were more frequently bridged to heart transplantation [20.0% (n=20) vs 0.3% (n=1), p&lt;0.001] or LVAD [4.0% (n=4) vs 0.6% (n=2), p=0.055] than ACS patients; mortality after transplantation/LVAD did not significantly differ between the two groups [12.5% (n=3/24) vs 66.7% (n=2/3), p&gt;0.05]. The incidence of IABP-related overall and major complications (including ischemic stroke, major bleeding, and peripheral or visceral ischemia) was not different with respect to the non-ACS vs ACS aetiology [major complications: 8.0% (n=8) vs 5.0% (n=15), p&gt;0.05].

Conclusions

In our experience, in the clinical setting of CS treated with IABP, non-ACS patients show a worse clinical profile and prognosis than ACS patients, and more often require escalation to more advanced mechanical support and/or heart transplantation, while the incidence of IABP-related complications appears similar independently of the aetiology.

Funding Acknowledgement

Type of funding sources: None.

P192 LONG TERM PROGNOSTIC EFFECT OF LIPROTEIN(A) IN PATIENTS WITH AND WITHOUT DIABETES MELLITUS AFTER MYOCARDIAL INFARCTION

Aims

To describe the baseline clinical, laboratory and angiographic characteristics of patients with acute myocardial infarction (MI) according to the presence or not of diabetes mellitus (DM), and to evaluate if DM may influence the effect of lipoprotein(a) [Lp(a)] serum level on long–term outcome in this very high–risk population.

Methods

This was a retrospective, single–center, study including consecutive patients admitted with MI diagnosis between January 1, 2017, and December 31, 2020. The availability of data on baseline Lp(a) serum level was considered as an inclusion criterion. The study population was divided into two groups according to the presence or not of DM. The Lp(a) value of 50 mg/dL was used to test the hypothesis of a different effect of Lp(a) on the clinical outcome of patients with or without DM. The primary study outcome was all–cause death at 3–year follow–up.

Results

The study population included 997 patients (mean age 63.7±13.5 years; 75.7% were males). Diabetes was reported in 280 (28.1%) patients. DM patients were older than those without DM (67.8±12.1 vs. 62.0±13.7 years, p &lt; 0.001) and showed a significantly higher prevalence of dyslipidemia, hypertension, obesity, prior MI and prior coronary revascularization (p &lt; 0.001). DM patients showed higher SYNTAX score value (19.8 vs. 15.1, p &lt; 0.001) and a higher prevalence of left main involvement (6.3 vs. 3.1, p = 0.023). At Kaplan–Meier analysis, in the group without DM, patients with Lp(a)≥50 mg/dL showed a significantly lower long–term survival compared with those with Lp(a)&lt;50 mg/dL (Log–Rank=0.004). In DM patients DM, conversely, no survival difference was found between patients with Lp(a)≥50 mg/dL vs. those with Lp(a)&lt;50 mg/dL. At multivariable Cox regression analysis, in patients without DM, Lp(a) serum level (HR: 2.68, 95% CI 1.23–5.83; p = 0.013) and age (HR: 1.06, 95% CI 1.04–1.09; p &lt; 0.001) were independent predictors of mortality at 3–year follow–up. Among DM patients, only age was independently associated with 3–year mortality (HR: 1.07, 95% CI 1.03–1.10; p &lt; 0.001) (Table).

Conclusion

In this MI population, Lp(a) was independently associated with long–term mortality in patients without DM, but not in patients with DM. Whether DM can modify the effect of Lp(a) on clinical outcome after MI requires confirmation by larger prospective studies.

Telemedicine (TM) during SARS-CoV-2 Outbreak

Purpose

As Italy faced SARS-CoV-2 outbreak as first country outside China, and our hospital converted most of activities into the ones for COVID-19 patients (pts), we had to manage the need for continuing care of advanced heart failure (HF), heart transplant (HT) and LVAD pts. TM was a possible strategy, but its role in this very sick cohort is unknown.

Methods

During the lockdown (03-05/2020), we decided to make either a phone (PV) or an in presence (IV) visit, selecting for IV pts listed for HT, with LVAD, recently HT, scheduled for a biopsy within 6 months after HT or a RHC for listing eligibility. In PV, we assessed symptoms, blood pressure, drugs, and programmed a subsequent IV. All pts in IV group were triaged by phone for COVID-19 symptoms or contacts and if scheduled for RHC or biopsy received SARS-CoV-2 swab 48 h before the procedure. Study endpoints were: combined incidence at 6 months of MACE (HF hospitalization, CV death and need for anticipated IV) in HF/VAD group, and MACE, rejection and any cause- hospitalization in HT group.

Results

Among 448 pts (57±12y, 240 HT, 191 HF, 17 LVAD), 52% were managed by PV and a subsequent IV was scheduled after 3±2 months. Pts managed by PV were healthier: in HF-VAD group they were less frequently listed, had less Afib, LVAD (2/17) (p<0.01 all); post-capillary PH (pC-PH) was similarly distributed; in HT group there were less pts transplanted in the last 5 years (15% vs 52%, p<0.01) and numerically less with 2R rejection in the previous 6 months (8.3% vs 27.1%, p=0.13).The PV group had a lower incidence of the endpoints in both HF/VAD and HT cohorts (92.3±2.3% vs 70.3±4.4%; 97.0±1.7%vs82.5±4.1%, p<0.01). Overall, the predictors of the endpoints at multivariate analysis were pC-PH and PV (HR: 5.2 and 0.1, p<0.03 both) and a recent 2R rejection (HR: 3.6, p=0.05) in the HF/VAD and HT group respectively.There were no cases of COVID-19 in IV; 5 pts got infected at home in a context of infection prevalence of 6/1000 inhabitants in our region and of 40% of hospital beds dedicated to COVID-19 pts.

Conclusion

In this retrospective study, by reporting an organization set up in a emergency situation, we show that TM can be safely used to manage stable HF, LVAD and HT patients, whereas pC-PH and a recent rejection may identify those needing IV. These data suggest that the availability of devices for monitoring pulmonary pressures may improve safety of PV in HF pts and that TM could be useful not only in a pandemic outbreak but also subsequently.

Prognostic value and usefulness of Pulmonary Artery Pulsatility index (PAPi) in evaluation of heart transplant candidates

Background

Heart transplantation (HTx) is considered the best available treatment for patients with end stage heart failure. Candidate evaluation with right heart catheterization (RHC) is fundamental in order to exclude pulmonary hypertension with irreversible high pulmonary vascular resistance (PVR), which is associated with elevated post-HTx mortality. PVR, rather than directly measured, is derived by cardiac output and pulmonary artery pressures, which are strictly dependent on right ventricular (RV) function. The pulmonary artery pulsatility index (PAPi) is a hemodynamic parameter integrating the information of RV function and of pulmonary circulation, which could be useful in pre-HTx evaluation.

Purpose

We designed this study to evaluate the potential predictive influence of pre-HTx PAPi on post-HTx survival and to assess whether this index could add useful information in the pre-HTx evaluation of patients with advanced heart failure.

Methods

Consecutive adult HTx recipient at two medium-large tranplant centers between 2000 and 2017 with available data on pre-HTx RHC were retrospectively included. PAPi was calculated as the ratio of pulmonary artery pulse pressure to right atrial pressure. PAPi values in the lowest quartile were defined as reduced (PAPi&lt;1.67). The primary endpoint was all-cause mortality at 1-year post-HTx. The association of reduced PAPi with the primary endpoint was evaluated. Cox regression was used to adjust for clinical and hemodynamic variables. Analyses stratified by PVR status (≥3 WU vs. &lt;3 WU) were also performed.

Results

Among 655 HTx recipients (female 20,8%, age 53±11 years), median pre-HTx PAPi was 3.0 (interquartile range 1.67–5.32). Patients in the lowest versus the remaining PAPi quartiles had significantly reduced 1-year survival (78.0% vs 87.2%, p=0.006), also after adjusting for age, estimated glomerular filtration rate, total bilirubin, high PVR and urgent transplantation (adj-hazard ratio: 0.64; 95% confidence interval 0.51–0.82). When stratifying patients by estimated PVR status, reduced PAPi was associated with worse 1-year survival among patients with normal PVR (78.3% vs. 88.3% p=0.011), but not in those with increased PVR (78.0% vs. 82.6%, p=0.36) (Figure 1).

Conclusions

Pre-HTx PAPi, integrating information of RV function and pulmonary circulation, provides incremental prognostic value over traditional clinical and hemodynamic parameters among HTx recipient. The prognostic value appears important among patients with normal estimated PVR, possibly due to an underestimation of PVR in patients with impaired RV function. The integration of PAPi in the pre-HTx evaluation may lead to better patient selection and post-HTx survival.

Figure 1. 1 year survival stratified by PVR status

Funding Acknowledgement

Type of funding source: None

UFT/leucovorin and oxaliplatin alternated with UFT/leucovorin and irinotecan in metastatic colorectal cancer

A total of 41 metastatic colorectal cancer (CRC) patients received tegafur/uracil (UFT)+leucovorin (LV)+oxaliplatin alternated with UFT/LV+irinotecan. The overall response rate was 58.5% (95% confidence interval, 42.2-73.3%), and the median progression-free survival was 8.8 months. There were no grade 4 toxicities; 12 patients (29%) experienced grade 3 diarrhoea. There were no cases of hand-foot syndrome. This alternating regimen seems to be effective and well tolerated in the first-line treatment of patients with metastatic CRC.

A novel biweekly pancreatic cancer treatment schedule with gemcitabine, 5-fluorouracil and folinic acid

Pancreatic adenocarcinoma is a common disease considered to be poorly responsive to antiblastic treatment. Recent clinical and preclinical results suggest that a combined treatment of gemcitabine (GEM), 5-flurouracil (5-FU) and folinic acid (FA) offers a clinical benefit in patients with advanced pancreas adenocarcinoma. The aim of this phase II clinical trial was to evaluate the antitumour activity and toxicity of a novel biweekly schedule of this combination in patients with pancreatic adenocarcinoma. A total of 42 patients received a 30 min infusion of FA (100 mg m(-2)) and 5-FU (400 mg m(-2)) (FUFA) on days 1-3, and GEM 1000 mg m(-2) on day 1 every 15 days. We observed 13 objective responses (two complete, 11 partial) and 23 stable diseases. The median time to progression was 9.75 months (95% Confidence Interval (CI), 6.88-12.62) and the median overall survival was 13.10 months (95% CI 9.64-16.56). There were seven cases of each grade III gastroenteric and haematological toxicity. The GEM plus FUFA combination appears to be well tolerated and very active in patients with pancreatic carcinoma.

Gemcitabine increases systemic 5-fluorouracil exposure in advanced cancer patients

A number of recent clinical trials testing the combination of 5-fluorouracil (5-FU) and gemcitabine in patients with advanced pancreatic adenocarcinoma have shown a significant clinical response rate, but also significant toxicity. As the two antimetabolites may interact at several biochemical levels along their pathways of activation, we investigated whether gemcitabine (GEM) affects 5-FU pharmacokinetics in cancer patients. Thus, we compared 5-FU pharmacokinetics in two groups of patients with various cancers who received the same schedule of 5-FU and folinic acid (FUFA), with or without GEM. There was a significant increase in systemic (5-FU) exposure and toxicity in the FUFA plus GEM group. Our finding may be useful in designing future studies of the combination in order to reduce the occurrence of side-effects and to maximise the antitumour activity.

Weekly epirubicin in patients with hormone-resistant prostate cancer

The aim of this study was to investigate the benefit of weekly epirubicin in the treatment of metastatic hormone-resistant prostate cancer. One hundred and forty-eight patients with metastatic hormone-resistant prostate cancer received weekly 30-min intravenous infusions of epirubicin 30 mg m(2) of body surface area. The primary end-point was palliative response, defined as a reduction in pain intensity and an improvement in performance status. The secondary end-points were the duration of the palliative response, quality of life and survival. Fifty-seven (44%) of the 131 evaluable patients met the primary criterion of palliative response after six treatment cycles and 73 (56%) after 12 cycles; the median duration of the response was 9 months (range 1-11). The median global quality of life improved in 52% of the patients after six cycles and in 68% after 12 cycles. The 12- and 18-month survival rates were respectively 56 and 31%, with a median survival of 13+ months (range 1-36). The treatment was well tolerated: grade 3 neutropenia was observed in 8% of the patients, grade 3 anaemia in 7%, and grade 3 thrombocytopenia in 3%. None of the patients developed grade 4 toxicity or congestive heart failure. Weekly epirubicin chemotherapy can lead to a rapid and lasting palliative result in patients with metastatic HRPC, and have a positive effect on the quality of life and survival.

Tumour-associated antigen (TAA)-specific cytotoxic T cell (CTL) response in vitro and in a mouse model, induced by TAA-plasmids delivered by influenza virosomes

We investigated influenza virosomes as a TAA-gene delivery system for use in TAA-directed anti-cancer vaccine therapy. An engineered plasmid (GC90) expressing the parathyroid hormone-related peptide (PTH-rP), a protein secreted by prostate and lung carcinoma cells, was included in influenza virosomes (GC90V). The ability of GC90V to elicit a PTH-rP-specific cytotoxic T cell (CTL) response was demonstrated in BALB/c mice immunised with intranasal (i.n.) GC90V+/-adjuvant subcutaneous (s.c.) interleukin-2 (IL-2). A PTH-rP-specific CTL response with antitumour activity was also demonstrated in human peripheral blood mononuclear cells (PBMC) stimulated in vitro with GC90V infected autologous dendritic cells (DC). These results provide a rationale for investigating GC90V in clinical trials of anticancer vaccine therapy.

A parathyroid-hormone-related-protein (PTH-rP)-specific cytotoxic T cell response induced by in vitro stimulation of tumour-infiltrating lymphocytes derived from prostate cancer metastases, with epitope peptide-loaded autologous dendritic cells and low-dose IL-2

Bone metastases are one of the most common events in patients with prostate carcinoma. PTH-rP, a protein produced by prostate carcinoma and other epithelial cancers, is a key agent for the development of bone metastases. A PTH-rP-derived peptide, designated PTR-4 was identified, which is capable to bind HLA-A2.1 molecules and to generate PTH-rP-specific cytotoxic T cell (CTL) lines from healthy HLA-A2.1(+) individual peripheral-blood-mononuclear-cells (PBMC). In this model, we investigated the in vitro possibility of generating an efficient PTH-rP specific CTL response by cyclical stimulations with IL-2 and PTR-4 peptide-pulsed autologous dendritic cells (DC), of HLA-A2.1(+) tumour infiltrating lymphocytes (TIL) derived from a patient with metastatic prostate carcinoma. A T cell line generated in this way (called TM-PTR-4) had a CD3(+), CD5(+), CD4(-), CD8(+), CD45(Ro+), CD56(-) immunophenotype and a HLA-A2.1 restricted cytotoxic activity to PTR-4-peptide pulsed CIR-A2 (HLA-A2.1(+)) target cells, PTH-rP(+)/HLA-A2.1(+) CIR-A2 transfected with PTH-rP gene, prostate carcinoma LNCaP cells, and autologous metastatic prostate cancer cells (M-CaP). These lymphocytes were not cytotoxic to HLA-A2.1(+) targets not producing PTH-rP, such as peptide-unpulsed CIR-A2 and colon carcinoma SW-1463, cell lines. Our results provide evidence that PTR-4 peptide-pulsed autologous DC may break the tolerance of human TIL against the autologous tumour by inducing a PTH-rP-specific CTL immune reaction. In conclusion PTR-4 peptide-pulsed autologous DC may be a promising approach for vaccine-therapy and antigen-specific CTL adoptive immunotherapy of hormone-resistant prostrate cancer.

In vitro generation of cytotoxic T lymphocytes against HLA-A2.1-restricted peptides derived from human thymidylate synthase

5-Fluorouracil (5-FU) is a pyrimidine antimetabolite active against colorectal carcinoma and other malignancies of the digestive tract. Over-expression or mutation of thymidylate synthase (TS), the target enzyme of the 5-FU metabolite, 5-fluorodeoxyuridine monophosphate, is strictly correlated with cancer cell resistance to 5-FU. On this basis we investigated whether TS is a potential target for active specific immunotherapy of human colon carcinoma, which acquires resistance to 5-FU. Three TS-derived epitope peptides which fit defined amino acid consensus motifs for HLA-A2.1 binding were synthesized and investigated for their ability to induce human TS-specific cytotoxic T cell (CTL) responses in vitro. CTL lines specific for each peptide were established by stimulating peripheral blood mononuclear cells (PBMC) from an HLA-A2.1+ healthy donor with autologous dendritic cells loaded with TS peptide. Specific CTL lines showed HLA-A2.1-restricted cytotoxicity in vitro to HLA-A2.1+ target cells pulsed with the specific TS peptide and to HLA-class I matching colon carcinoma target cells over-expressing TS enzyme after exposure to 5-FU. Recognition by CTL lines suggests that these TS peptides may be potential candidates for use in a peptide-based vaccine against 5-FU resistant colon carcinoma.

Comparative study of the immune response in mice immunized with four live attenuated strains of mumps virus by intranasal or intramuscular route

The observation of many cases of mumps and mumps-associated CNS complications in vaccinees prompted us to perform an evaluation of the efficacy of four attenuated mumps virus (Urabe, Jeryl Lynn, Rubini and S12) vaccines. Two doses of vaccine were necessary to induce a good immunity in animals. The humoral and cell-mediated response induced in mice immunized intramuscularly or intranasally with these vaccines has been evaluated. Although the Urabe and Jeryl Lynn strains appear more immunogenic than the other strains and induce higher levels of IgG when administered intramuscularly, the S-12 strain administered intranasally induces a good IgG response. A marked specific CTL activity against mumps virus was observed in mice immunized intranasally with all the strains and, particularly, with the S12 strain. Thus, the intranasal immunization could be considered a possible alternative and efficient route of vaccination against mumps.

Recruitment of dendritic cells and enhanced antigen-specific immune reactivity in cancer patients treated with hr-GM-CSF (Molgramostim) and hr-IL-2. results from a phase Ib clinical trial

Experimental findings suggest that granulocyte-monocyte-colony stimulating factor (GM-CSF) synergistically interacts with interleukin-2 (IL-2) in generating an efficient antigen-specific immune response. We evaluated the toxicity, antitumour activity and immunobiological effects of human recombinant (hr)-GM-CSF and hr-IL-2 in 25 cancer patients who subcutaneously (s.c.) received hr-GM-CSF 150 microg/day for 5 days, followed by hrIL-2 s.c. for 10 days and 15 days rest. Two of the most common side-effects were bone pain and fever. Of the 24 patients evaluable for response, 3 achieved partial remission, 13 experienced stable disease, and 8 progressed. Cytokine treatment increased the number of monocytes, dendritic cells (DC), and lymphocytes (memory T cells) in the peripheral blood and enhanced the antigen-specific immunoreactivity of these patients. Our results show that the hr-GM-CSF and hr-IL-2 combination is active and well tolerated. Its biological activity may support tumour associated antigen (TAA)-specific anticancer immunotherapy by increasing antigen presenting cell (APC) activity and T cell immune competence in vivo.

Acetylcholine receptor activation enhances NMDA-mediated responses in the rat neostriatum

The influence of acetylcholine (ACh) upon N-methyl-D-aspartate (NMDA) receptor activation of neostriatal neurons is unknown. In the present study, we used both in vitro intracellular and in vivo electroencephalographic recordings in rats to examine this question. In vitro, iontophoretic application of carbachol, a cholinergic receptor agonist, significantly increased the NMDA-mediated response of neostriatal projection neurons. Carbachol alone had mild excitatory effects. In vivo, intrastriatal NMDA produced focal epileptiform activity restricted to the neostriatum. NMDA applied in conjunction with carbachol produced significantly greater epileptiform activity which propagated to the neocortex. These results suggest that ACh and NMDA receptor co-activation leads to potentiation of the neuronal responses both at the site of the interaction and at the endpoint of the cortico-striato-cortical circuit.

Neuropsychology of selective attention and magnetic cortical stimulation

Informed volunteers were asked to perform different neuropsychological tests involving selective attention under control conditions and during transcranial magnetic cortical stimulation. The tests chosen involved the recognition of a specific letter among different letters (verbal test) and the search for three different spatial orientations of an appendage to a square (visuo-spatial test). For each test the total time taken and the error rate were calculated. Results showed that cortical stimulation did not cause a worsening in performance. Moreover, magnetic stimulation of the temporal lobe neither modified completion time in both verbal and visuo-spatial tests nor changed error rate. In contrast, magnetic stimulation of the pre-frontal area induced a significant reduction in the performance time of both the verbal and visuo-spatial tests always without an increase in the number of errors. The experimental findings underline the importance of the pre-frontal area in performing tasks requiring a high level of controlled attention and suggest the need to adopt an interdisciplinary approach towards the study of neurone/mind interface mechanisms.

Effects of desipramine and alprazolam on forced swimming behaviour of adult rats exposed to prenatal diazepam

Pregnant rats were treated with a single daily s.c. injection of diazepam (2 mg/kg) over gestation days 14-20. This treatment led to a reduction in GABA receptor complex function since adult male offspring showed a strong decrease in electrographic hippocampal responses to alprazolam and a strongly increased response to picrotoxin after intra-locus coeruleus injection of the two compounds. No difference in immobility time in the forced swimming test and in spontaneous motor activity was observed between prenatally vehicle- and diazepam-exposed offspring. Conversely, prenatal exposure to diazepam potentiated the anti-immobility effect of subchronic desipramine (10 mg/kg i.p.) and made active a dose of desipramine (5 mg/kg i.p.) that was ineffective in prenatally vehicle-exposed rats. This effect was observed only in pretested rats. Prenatal exposure to diazepam blocked the anti-immobility effect of subchronic alprazolam (15 mg/kg i.p.) in both non-pretested and pretested rats. Spontaneous motor activity was strongly reduced in all groups. These findings suggest that a persistent reduction in GABA receptor complex function, induced by prenatal exposure to diazepam, does not alter the mobility of adult progeny in the forced swimming test, but it may have consequences when drugs acting on the GABA receptor complex are used.

Cortical stimulation and reflex excitability of spinal cord neurones in man

The H reflex technique was used to evaluate the influence exerted by cortical conditioning on the excitability of the alpha-motoneurone pool and on IA interneuronal activity (reciprocal inhibition). In ten subjects at absolute rest electrical and magnetic stimulation of the motor cortex was transcranially applied during flexor carpi radialis H reflex eliciting and in conditions of reciprocal inhibition induced by radial nerve stimulation. The time courses showed that at intensities below motor threshold, electrical brain conditioning induced an increase in the amplitude of the test reflex when the cortical shock was given 4 ms after the test H reflex. On the contrary, reciprocal inhibition was reduced by electrical cortical conditioning when the scalp stimulation was applied 2-3 ms after the test stimulus. Magnetic transcranial stimulation induced an increase of H reflex amplitude when the test shock was administered 5 and 2 ms prior to the scalp shock; it did not modify the degree of reciprocal inhibition. The experimental findings could be considered the electrophysiological manifestation of a differential cortico-spinal control on the pathway alpha-motoneurone/IA interneurone. Considerations on the delay allow the hypothesis of a further synapse between the cortico-spinal ending and the IA interneurone. Discrepancies with magnetic conditioning might be ascribed to a preferential transsynaptic action of magnetic mode of neural activation.

Locus coeruleus noradrenaline system and focal penicillin hippocampal epilepsy: neurophysiological study

Previous experimental investigations have shown that several neuronal systems modulate the spontaneous and paroxysmal electric activity of the hippocampus. The locus coeruleus-noradrenaline (LC-NA) system exerts an inhibitory influence on several brain areas including the ipsilateral hippocampus. Selective destruction of the LC increases the susceptibility to epileptiform phenomena in different models of experimental epilepsy. Our experiments were conducted on 34 rats in which a steady epileptiform interictal activity of the hippocampus was obtained by means of intrahippocampal administration of penicillin. Electrical stimulation of LC caused a significant decrease of penicillin spiking of hippocampus. Stimulation sessions given 10-15 min after i.p. propranolol administration (2 mg/kg) failed to induce any significant modification in the hippocampal spiking frequency. Intrahippocampal injection of L-noradrenaline mimicked the inhibitory effect of LC electrical stimulation on hippocampus. Finally, intrahippocampal administration of isoproterenol HCl, a beta-adrenoceptor agonist, caused a significant decrease of hippocampal penicillin spiking; this effect was antagonised by i.p. propranolol administration. The experimental data show a modulating influence of the LC-NA system on penicillin focal hippocampal epilepsy that probably involves beta-adrenoceptors.

NMDA-GABA interactions in an animal model of behaviour: a gating mechanism from motivation toward psychotic-like symptoms

We studied the effects of desipramine, alprazolam, muscimol and dizocilpine (MK-801) (alone or associated with desipramine) in the forced swimming test in rats after long-lasting termination of chronic exposure to vehicle and pentylenetetrazol. Sensitisation with pentylenetetrazol was ineffective in changing immobility time in the forced swimming test compared to vehicle treatment; pentylenetetrazol enhanced the anti-immobility effect of desipramine, abolished the anti-immobility effect of alprazolam and did not affect the anti-immobility effect of muscimol. MK-801 at the dose that did not modify immobility time in vehicle-treated rats and in pentylenetetrazol-treated animals strongly potentiated the anti-immobility effect of desipramine in pentylenetetrazol-treated rats. MK-801 in association with desipramine induced a marked hyperlocomotion and hyperexcitability, with swaying movements and oral stereotypies in pentylenetetrazol-sensitised rats. Results are considered the experimental representation of a 'gating mechanism' toward psychotic-like symptoms.

Anticonvulsant activity of the noradrenergic locus coeruleus system: role of beta mediation

Many experimental observations have demonstrated the modulatory role exerted by several neural structures and neurotransmitters on spontaneous and paroxysmal bioelectric activity of the hippocampus. Recently, the control exerted by locus coeruleus (LC) and its noradrenergic (NA) efferent pathway on different experimental models of epilepsy (e.g. cortical cobalt chronic epilepsy, amygdaloid and hippocampal kindling) was emphasised. On this basis, a series of experiments was performed to elucidate the functional role of LC-NA system on the hippocampal penicillin (PCN) focus and the type of adrenergic receptor involved. The experiments were carried out on 25 rats in which an epileptiform hippocampal focus was obtained through intrahippocampal PCN administration (100-200 I.U.). In these conditions, LC, ipsilateral to PCN hippocampal focus, was stimulated before and after intraperitoneal (i.p.) administration of a beta-adrenergic receptor antagonist propranolol (2 mg/kg). Results showed a significant reduction of hippocampal spiking frequency during LC stimulation; after i.p. propranolol injection, LC stimulation, at the same parameters, failed to induce any sort of modification of PCN hippocampal spiking frequency. Furthermore, intrahippocampal application of a beta-selective agonist 2-fluoro-noradrenaline (2-FNA) mimics the inhibitory effects of LC stimulation. All data suggest that the LC-NA system is able to induce a net reduction of hippocampal epileptiform focus and the inhibitory NA control involves the activation of adrenergic beta receptors.

Bilateral reciprocal organisation in man: focus on IA interneurone

The H reflex of flexor carpi radialis and radial-induced reciprocal inhibition were recorded in normal subjects during conditioning stimulation of the contralateral median or radial nerves. It was found that stimulation of the contralateral median nerve enhanced the degree of reciprocal inhibition exerted by the radial nerve on the median nerve, while contralateral radial nerve stimulation reduced the reciprocal inhibition exerted by the extensor on the flexor. In two subjects in which a pure extensor H reflex was recorded specular features were observed following contralateral median and radial stimulation. These findings are considered to be the electrophysiological manifestation of contralateral modulation of reciprocal inhibition, which is likely to act at the level of the IA interneurone.

Effects of desipramine and alprazolam in the forced swim test in rats after long-lasting termination of chronic exposure to picrotoxin and pentylenetetrazol

Rats were treated for 5 weeks with three subconvulsant doses of picrotoxin (PTX) and pentylenetetrazol (PTZ) per week to induce a persistent reduction of the GABAA receptor function which results in chemical kindling. Fifteen days after termination of this treatment schedule, the effect of desipramine (DMI) and alprazolam (ALP) on immobility time in the forced swim test (FST) was evaluated. Chronic PTX and PTZ did not alter the immobility time. Acute PTX and PTZ reduced the immobility of rats chronically treated with vehicle but not of those exposed chronically to PTX and PTZ. Chronic PTX did not influence the anti-immobility effect of DMI, but blocked that of ALP. Chronic PTZ markedly potentiated the anti-immobility effect of DMI but blocked that of ALP. Concomitant administration of chlordiazepoxide prevented the effects of chronic PTX and PTZ. These findings suggest that a long-lasting reduction in GABAA receptor function, unlike acute reduction, does not play an important role in the mobility of rats in the FST and in the anti-immobility effect of DMI while it blocks that of ALP.

Evidence of a contralateral motor influence on reciprocal inhibition in man

The role of contralateral movement on both H reflex and reciprocal inhibition was studied. In normal men H reflex was induced by median nerve stimulation. Reciprocal inhibition was achieved through stimulation of the antagonist radial nerve. On this basis the effects of contralateral arm movement were analyzed. Furthermore the putative influence of exteroceptive origin was also verified by means of digit stimulation. Results showed that contralateral arm movement did not affect H reflex amplitude; on the contrary, it was able to enhance reciprocal inhibition induced by extensors on flexors. Study of cutaneous afferents demonstrated that contralateral digit stimulation failed to elicit modifications on both H reflex and reciprocal inhibition. On the other hand, ipsilateral digit stimulation lowered H reflex amplitude and increased the degree of reciprocal inhibition. Experimental findings underline the possibility that an informational array reaches the contralateral IA interneuron: therefore a mutual (bilateral) interaction among IA interneurones may accordingly be hypothesised.

Accumbens-caudate-septal circuit as a system for hippocampal regulation: involvement of a GABAergic neurotransmission

Hippocampal-based epileptiform activity may reach the basal ganglia via the nucleus accumbens. Previous data suggested that caudate nucleus is able to influence hippocampal epilepsy, probably sending a projection to the septum. In order to test the hypothesis of a retrograde activation of accumbens-caudate pathway in hippocampal regulation, we electrically stimulated both caudate nucleus and nucleus accumbens and studied modifications of hippocampal EEG in the feline focal epilepsy model. We also performed bilateral electrolytic lesion of nucleus accumbens and repeated caudate stimulation. Results showed that nucleus accumbens stimulation was ineffective in modifying hippocampal epilepsy; on the contrary, caudate stimulation caused a statistically significant decrease of hippocampal spike frequency and amplitude. On the other hand, in accumbens-lesioned animals caudate activation consistently reduced hippocampal epilepsy to a significant degree. As the caudate nucleus influences hippocampal activity and the septum may constitute a relay station of this functional relation, a possibility was tested concerning a GABAergic mediation. To this end, after a stable caudate-induced effect was reached, an intraseptal microinjection of picrotoxin (GABA receptor antagonist) was made and caudate stimulation repeated at the same parameters. Such a study showed that after intraseptal picrotoxin, caudate stimulation failed to elicit any type of modification of hippocampal activity. Experimental findings support the notion that the striatal modulation on hippocampus is mediated by an anterograde rather than a retrograde pathway, and underline the possibility of a GABAergic caudate-septal influence.

Electrophysiological and microiontophoretic analysis of the habenulo-hippocampal circuit

In the cat, the effects of lateral habenula stimulation, at different ranges of frequency, on hippocampal units were studied. Habenular stimulation at low frequency excited, while at high frequency inhibited the greater part of hippocampal units. Moreover, in order to clarify the possible pathway involved in the habenulo-hippocampal circuit, the effects of iontophoretic acetylcholine and serotonin on hippocampal units were compared with those of habenular stimulation. Iontophoretic acetylcholine induced both excitatory and inhibitory responses while serotonin induced only inhibitory responses. Iontophoretic atropine blocked the effects of acetylcholine ejection but did not antagonize stimulation effects; ion-tophoretic methysergide induced an increase of basal firing of hippocampal units and antagonized both serotonin and habenular stimulation inhibition. The results suggest an influence of lateral habenula to the hippocampus which does not appear to be cholinergically-mediated. A possible involvement of the raphe as a relay station in the habenulo-hippocampal pathway is discussed.

A feature of caudate control of focal hippocampal epilepsy: evidence for an anterograde pathway

Previous experimental evidences showed that the caudate nucleus has a modulatory effect on hippocampal epilepsy. The caudate's regulating action might reach the hippocampus either via the septal region or, retrogradely, via the accumbens nucleus. In order to obtain new data about the pathway involved in caudate hippocampal influence the spreading of abnormal activity towards the nucleus accumbens was studied. Furthermore the effects of caudate stimulation in animals with electrolytic lesions of the nucleus accumbens were analyzed. It was observed that abnormal penicillin-induced activity spreaded from the hippocampus to the nucleus accumbens in about 30 minutes. In animals with and without lesions of nucleus accumbens, caudate stimulation brought about a significant decrease in the frequency and amplitude of hippocampal activity. The results suggest that the nucleus accumbens is reached by the spreading of hippocampal epilepsy but does not participate in the control exerted by the caudate nucleus on the hippocampus. Thus the caudate-induced inhibition takes place through an anterograde caudate-hippocampal circuit, while at the same time excluding retrograde activation by way of a caudate-accumbens-hippocampal pathway.