Perampanel as only add-on epilepsy treatment in elderly: A subgroup analysis of real-world data from retrospective, multicenter, observational study

INTRODUCTION

Drug management of epilepsy in the elderly presents unique but data on this population are scarce. This study aimed to assess the effectiveness and tolerability of perampanel (PER) used as only add-on to a background anti-seizure medication (ASM) in the elderly in a real-world setting.

METHODS

We performed a subgroup analysis of patients aged ≥65 years included in a previous 12-month multicenter study on adults. Treatment discontinuation, seizure frequency, and adverse events were recorded at 3, 6 and 12 months after PER introduction. Sub-analyses by early (≤1 previous ASM) or late PER add-on were also conducted.

RESULTS

The sample included 65 subjects (mean age: 75.7 ± 7.2 years), with mainly focal (73.8%) epilepsy. The mean PER daily dose was ≈4 mg during all follow-up. Retention rates at 3, 6, and 12 months were 90.5%, 89.6%, and 79.4%ly. The baseline median normalized per 28-day seizure number significantly decreased at 3-, 6- and 12-month visits. One year after PER introduction, the responder rate (≥50% reduction in baseline seizure frequency) was 89.7%, with a seizure freedom rate of 72.4%. Adverse events occurred in 22 (34.9%) patients with dizziness and irritability being the most frequent. No major differences between early (41 patients, 63.1%), and late add-on groups were observed.

CONCLUSION

Adjunctive PER was effective and well-tolerated when used as only add-on treatment in elderly people with epilepsy in clinical practice, thus representing a suitable therapeutic option in this age category.

Effectiveness of Perampanel as the Only Add-on: Retrospective, Multicenter, Observational Real Life Study on epilepsy patients

OBJECTIVE

Perampanel (PER) is indicated as adjunctive antiseizure medication (ASM) in adolescents and adults with epilepsy. Data from clinical trials show good efficacy and tolerability, while limited information is available on the routine clinical use of PER, especially when used as only add-on treatment.

METHODS

we performed an observational, retrospective, multicenter study on people with focal or generalized epilepsy aged >12 years, consecutively recruited from 52 Italian epilepsy centers. All patients received PER as the only add-on treatment to a background ASM according to standard clinical practice. Retention rate, seizure frequency and adverse events were recorded at 3, 6 and 12 months after PER introduction. Sub-analyses by early or late use of PER and by concomitant ASM were also conducted.

RESULTS

503 patients were included (age 36.5±19.9 years). Eighty-one per cent had focal epilepsy. Overall, the retention rate was very high in the whole group (89% at 12 months) according with efficacy measures. No major differences were observed in the sub-analyses, although patients who used PER as early add-on, as compared with late add-on, more often reached early seizure freedom at 3 months follow-up (66% vs. 53%, p=0.05). Treatment-emergent adverse events occurred in 25%, far less commonly than in PER randomized trials.

SIGNIFICANCE

this study confirms the good efficacy and safety of PER for focal or generalized epilepsy in real-life conditions. We provide robust data about its effectiveness as only add-on treatment even in patients with a long-standing history of epilepsy and previously treated with many ASMs.

Therapeutic approach to neurological manifestations of Angelman syndrome

INTRODUCTION

Angelman syndrome (AS) is a neurogenetic disorder due to deficient expression of the maternal copy of the UBE3A gene, which encodes ubiquitin ligase E3A protein. Severe developmental delay, seizures and other neurological disorders characterizes AS.

AREAS COVERED

In this review, we focus on a comprehensive therapeutic approach to the most disabling neurological manifestations of AS: epilepsy, sleep disturbances, behavioral and movement disorders. Articles were identified through PubMed and Google Scholar up to October 2021.

EXPERT OPINION

Evidence for the treatment of neurological manifestations in AS mainly derives from poor quality studies (case reports, small case series, expert opinions). Seizures can be polymorphic and includes atypical absences, myoclonic, generalized tonic-clonic, unilateral clonic, or atonic attacks. Sodium valproate, levetiracetam and benzodiazepines are the most commonly used anti-seizure medications. Melatonin or mirtazapine seem to improve sleep quality. Antipsychotics, antidepressants and anxiolytics have been proposed for treatment of behavioral manifestations, but no evidence-based studies are available. Non-pharmacological approach may also be useful. Mild dystonia is common but usually does not significantly impact patients' motor performances. Well-conducted clinical trials aimed to evaluate treatment of neurological complications of AS are warranted. Gene and molecular precision therapies represent a fascinating area of research in the future.

The relevance of MRI blood-sensitive sequences in the diagnostic assessment of late-onset epilepsy

OBJECTIVE

Sporadic cerebral amyloid angiopathy (CAA) is a degenerative brain small vessel disease of ageing resulting from progressive amyloid deposition in small arteries and arterioles of the cortex and leptomeninges. CAA may be diagnosed by the mean of Boston criteria, particularly with the use of the blood-sensitive T2* MRI sequences (GRE and SWI). Epileptic seizures have rarely been reported in CAA.

PATIENTS AND METHODS

We describe two patients with late-onset unprovoked seizures due to CAA. A short literature review on this topic is presented.

RESULTS

In our two patients with late-onset unprovoked seizures as the first manifestation of CAA, only GRE and SWI sequences lead to a correct diagnosis. In literature, only 15 patients with CAA presenting with seizures have been reported. In these subjects, data on seizures semiology and prognosis are scarce.

CONCLUSIONS

Our report highlights the importance to perform blood-sensitive sequences in all subjects with LOE of otherwise unknown etiology, not to miss a diagnosis of CAA.

Functional convergence spasm: an unexpected finding in a patient with focal epilepsy

OBJECTIVE

Convergence spasm is a clinical condition characterized by transient episodes of convergence, miosis and accommodation with strabismus and diplopia and it is usually a manifestation of a functional neurological disorder. We describe a patient with a challenging diagnosis of convergence spasm in the setting of occipital lobe epilepsy.

CASE REPORT

A 52-year-old woman came for the assessment of focal epilepsy due to left occipital cortical dysplasia. During ocular motility tests, she presented with episodes of short duration (~10-30 seconds) of convergent strabismus. Neuropsychological evaluation showed a severe mixed anxiety-depressive disorder with a tendency toward somatization.

RESULTS

Convergence spasm was recorded during video-EEG examination and no ictal activity was present.

CONCLUSIONS

To our knowledge, no other report of functional convergence spasm in the context of focal epilepsy associated with cortical dysplasia has been described in literature.

Therapeutic approach to difficult-to-treat typical absences and related epilepsy syndromes

Introduction: typical absences (TAs), are brief, generalized epileptic seizures of abrupt onset and termination clinically manifesting with impairment of awareness and associated with 3 Hz spike-wave discharges on EEG. TAs may occur in different idiopathic generalized epilepsies (IGE). Despite treatment with adequate anti-seizure medications (ASMs), TAs may persist in ~25% of subjects. This narrative review focuses on the therapeutic approach to difficult-to-treat TAs occurring in the setting of IGE.Areas covered: a literature search was conducted on the topic of treatment of TAs.Expert opinion: ethosuximide (ESX), valproic acid (VPA) and lamotrigine (LTG), alone or in combination, are considered the first-choice drugs. In women of childbearing potential, VPA should be avoided. Alternative therapies (benzodiazepines, levetiracetam, topiramate, or zonisamide) should be considered in subjects unresponsive to monotherapy after the exclusion of pseudo-drug resistance. Newer ASMs such as brivaracetam and perampanel seem to be promising options. Well-conducted clinical trials aimed to evaluate the efficacy of alternative monotherapy (beyond ESX, VPA or LTG) or combination of ASMs on difficult-to-treat TAs, are warranted.

Predictive factors of Status Epilepticus and its recurrence in patients with adult-onset seizures: A multicenter, long follow-up cohort study

PURPOSE

Status epilepticus (SE) is associated with high morbidity and mortality. This multicenter retrospective cohort study aims to identify the factors associated with the occurrence of SE and the predictors of its recurrence in patients with adult-onset seizures.

METHODS

We retrospectively analyzed data of 1115 patients with seizure onset>18 years, observed from 1983 to 2020 in 7 Italian Centers (median follow-up 2.1 years). Data were collected from the databases of the Centers. Patients with SE were consecutively recruited, and patients without SE history were randomly selected in a 2:1 ratio. To assess determinants of SE, different clinical-demographic variables were evaluated and included in univariate and multivariate logistic regression model.

RESULTS

Three hundred forty-seven patients had a SE history, whereas the remaining 768 patients had either isolated seizures or epilepsy without SE history. The occurrence of SE was independently associated with increasing age at onset of disease (OR 1.02, 95% CI 1.01--1.03, p<0.001), female sex (OR 1.39, 95% CI 1.05--1.83, p=0.02) and known etiology (OR 3.58, 95% CI 2.61--4.93, p<0.001). SE recurred in 21% of patients with adult-onset SE and recurrence was associated with increasing number of anti-seizure medications taken at last follow-up (OR 1.88, 95% CI 1.31--2.71, p<0.001).

CONCLUSIONS

In patients with adult-onset seizures, SE occurrence is associated with known etiologies, advanced age and female sex. Patients with recurrent SE are likely to have a refractory epilepsy, deserving careful treatment to prevent potentially fatal events.

Novel COL4A2 mutation causing familial malformations of cortical development

OBJECTIVE

This article aimed to describe a novel COL4A2 mutation and the phenotypic features of two family members presenting with epilepsy and cortical development malformations.

PATIENTS AND METHODS

The first patient is a 65-year-old woman with hematuria and adult-onset seizures. Brain MRI showed closed lip schizencephaly of right lateral sulcus associated with polymicrogyria of the surrounding cortex and areas of subcortical heterotopia. The second patient is a 40-year-old man, her son. He was born post-term with neonatal distress and psychomotor developmental delay with congenital left leg paresis and strabismus, as well as childhood-onset focal motor seizures. Brain MRI showed a right nucleus-capsular porencephalic cavitation with enlargement of the homolateral ventricle and a focal right occipital cortico-subcortical encephalomalacia. A small heterotopic band was also present in the frontal left subcortical region.

RESULTS

We tested both patients with a NGS panel for genetic epilepsies, which evidenced a missense mutation in COL4A2 gene (c.2972G>A, causing the aminoacidic substitution Gly991Glu).

CONCLUSIONS

The phenotypic spectrum associated with COL4A2 mutations has not been extensively described in the literature. Testing for COL4A mutations is indicated in patients with malformations of cortical development, particularly in the presence of familial conditions, even in the absence of porencephaly or early hemorrhagic strokes.

Epidemiology and Outcomes of Status Epilepticus

Status epilepticus (SE) is a neurological and medical emergency, defined as a condition resulting either from the failure of the mechanisms responsible of seizure self-limitation or from the initiation of mechanisms which lead to atypically prolonged seizures. Further than death, SE can have long-term consequences, including neuronal injury, depending on the type, cause and duration of seizures with severe associated disabilities. In Europe, SE shows an incidence rate ranging about 9 to 40/100,000/y. In adults, mortality of patients with SE is ~30%, and even higher (up to 40%) in refractory status epilepticus. To date, etiology, duration, presence of comorbidity, level of consciousness, semiology and age are the main clinical predictors of SE outcome.

Diagnostic and therapeutic approach to drug-resistant juvenile myoclonic epilepsy

INTRODUCTION

Juvenile myoclonic epilepsy (JME), also known as Janz syndrome, is a common form of generalized epilepsy of presumed genetic origin representing up to 10% of all epilepsy cases. Despite adequate anti-seizure medication (ASM) treatment, seizures persist in one-third of JME patients.

AREAS COVERED

A literature search was conducted using Pubmed search on the topics of drug-resistant JME.

EXPERT OPINION

About 30% of JME patients are drug-resistant. Valproate (VPA) is considered the first-choice drug. In women of childbearing potential, levetiracetam (LEV) should represent the first-choice treatment. Alternative monotherapy or add-on therapy should be considered in subjects with resistant seizures after the exclusion of pseudo-drug resistance. The choice of the add-on ASM depends on the predominant seizure type. In subjects with persistent bilateral tonic-clonic seizures, LEV or lamotrigine should be firstly considered. In patients with difficult-to-treat myoclonic seizures, clonazepam or LEV are recommended. In case of persistent absences, ethosuximide should be considered. With appropriate selection and safeguards in place, VPA should remain available as an option in women of childbearing potential whose seizures are resistant to other treatments.

Dystonia in Angelman syndrome: a common, unrecognized clinical finding

INTRODUCTION

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by cognitive disability, speech impairment, hyperactivity and seizures. Movement disorders have been reported in almost all AS subjects and they are described as "tremulous movements of limbs, unsteadiness, clumsiness or quick, jerky motions". The presence of dystonia has barely been mentioned in subjects with AS and has never been studied in detail. The purpose of this study is to evaluate the prevalence, clinical features and severity of dystonia in a series of adolescents and adults with AS.

METHODS

Whole body video recordings of patients with genetically confirmed AS were evaluated. Dystonia was evaluated by mean of the movement subscale of Burke-Fahn-Marsden Dystonia Rating Scale (BFM).

RESULTS

Forty-four subjects with AS were evaluated. Fourteen recordings were excluded due to poor cooperation. We finally analyzed data of 30 subjects (15 F) with a median age of 28 years (range 15-51). Dystonia was present in 28/30 (93.3%) subjects. Among these, dystonia involved the upper limbs in 28/28 (100%), lower limbs in 8/28 (28.5%), mouth in 7/28 (25%), neck in 3/28 (10.7%), trunk in 1/28 (3.6%). Severity of dystonia ranged from slight to moderate. There was a linear correlation between severity of dystonia and increasing age. There was no difference in terms of severity of dystonia among genetic subgroups.

CONCLUSIONS

Dystonia is a common and previously underrecognized clinical feature of adults and adolescents with AS.

Management of status epilepticus in patients with liver or kidney disease: a narrative review

Introduction: Status epilepticus (SE) is a neurologic and medical emergency with significant related morbidity and mortality. Hepatic or renal dysfunction can considerably affect the pharmacokinetics of drugs used for SE through a variety of direct or indirect mechanisms.Areas Covered: This review aims to focus on the therapeutic management of SE in patients with hepatic or renal impairment, highlighting drugs' selection and dose changes that may be necessary due to altered drug metabolism and excretion. The references for this review were identified by searches of PubMed and Google Scholar until May 2020.Expert opinion: According to literature evidence and clinical experience, in patients with renal disease, the authors suggest considering lorazepam as the drug of choice in pre-hospital and intra-hospital early-stage SE, phenytoin in definite SE, propofol in refractory or super-refractory SE. In patients with liver disease, the authors suggest the use of lorazepam as drug of choice in pre-hospital and intra-hospital early-stage SE, lacosamide in definite SE, propofol in refractory or super-refractory SE. A list of preferred drugs for all SE stages is provided.

Mental health care in Rome

Aim

To describe principles and characteristics of mental health care in Rome.

Method

Based on existing data, service provision, number of professionals working in services, funding arrangements, pathways tocare, user/carer involvement and specific issues are reported.

Results

After the Italian psychiatric reform of 1978, an extensive network of community-based services has been set up in Romeproviding prevention, care and rehabilitation in mental health. A number of small public acute/emergency inpatient units inside general hospitals was created (median length of stay in 2002 = 8 days) to accomplish the shift from a hospital-based to a community-based psychiatric system of care. Some private structures provide inpatient assistance for less acute conditions (median length of stay in 2002 = 28 days), whilst the large Roman psychiatric hospital was closed in 1999.

Discussion

Whilst various issues of mental health care in Rome overlap with those in other European capitals, there also are some specific problems and features. During the last two decades, the mental health system in Rome has been successfully converted to a community-based one. Present issues concern a qualitative approach, with an increasing need to foresee adequate evaluation, especially considering mental health patients' satisfaction with services and economic outcomes.

Younger age at stroke onset but not thrombolytic treatment predicts poststroke epilepsy: An updated meta-analysis

AIMS

Stroke is the most commonly identified cause of late-onset epilepsy. Risk factors for poststroke epilepsy (PSE) are partially elucidated, and many studies have been performed in recent years. We aimed to update our previous systematic review and meta-analysis on risk factors for PSE.

METHODS

PubMed, Google Scholar, and Scopus databases were searched. Articles published in English (1987-2019) were included. Odds ratios (OR) and mean values were calculated for examined variables.

RESULTS

Thirty studies with different designs were included, enrolling 26,045 patients who experienced stroke, of whom 1800 had PSE, corresponding to a prevalence of 7%. Cortical lesions (OR: 3.58, 95% confidence interval (CI): 2.35-5.46, p < 0.001), hemorrhagic component (OR: 2.47, 95% CI: 1.68-3.64, p < 0.001), early seizures (ES) (OR: 4.88, 95% CI: 3.08-7.72, p < 0.001), and younger age at stroke onset (difference in means: 2.97 years, 95% CI: 0.78 to 5.16, p = 0.008) favor PSE. Sex and acute treatment with recombinant tissue plasminogen activator (rtPA) do not predict the occurrence of PSE.

CONCLUSION

Despite limitations due to the uneven quality and design of the studies, the present meta-analysis confirms that cortical involvement, hemorrhagic component, and ES are associated with a higher risk of PSE. In this update, younger age at stroke onset but not thrombolytic treatment seems to increase the risk for PSE. This article is part of the Special Issue "Seizures & Stroke".

A Comprehensive Machine-Learning-Based Software Pipeline to Classify EEG Signals: A Case Study on PNES vs. Control Subjects

The diagnosis of psychogenic nonepileptic seizures (PNES) by means of electroencephalography (EEG) is not a trivial task during clinical practice for neurologists. No clear PNES electrophysiological biomarker has yet been found, and the only tool available for diagnosis is video EEG monitoring with recording of a typical episode and clinical history of the subject. In this paper, a data-driven machine learning (ML) pipeline for classifying EEG segments (i.e., epochs) of PNES and healthy controls (CNT) is introduced. This software pipeline consists of a semiautomatic signal processing technique and a supervised ML classifier to aid clinical discriminative diagnosis of PNES by means of an EEG time series. In our ML pipeline, statistical features like the mean, standard deviation, kurtosis, and skewness are extracted in a power spectral density (PSD) map split up in five conventional EEG rhythms (delta, theta, alpha, beta, and the whole band, i.e., 1-32 Hz). Then, the feature vector is fed into three different supervised ML algorithms, namely, the support vector machine (SVM), linear discriminant analysis (LDA), and Bayesian network (BN), to perform EEG segment classification tasks for CNT vs. PNES. The performance of the pipeline algorithm was evaluated on a dataset of 20 EEG signals (10 PNES and 10 CNT) that was recorded in eyes-closed resting condition at the Regional Epilepsy Centre, Great Metropolitan Hospital of Reggio Calabria, University of Catanzaro, Italy. The experimental results showed that PNES vs. CNT discrimination tasks performed via the ML algorithm and validated with random split (RS) achieved an average accuracy of 0.97 ± 0.013 (RS-SVM), 0.99 ± 0.02 (RS-LDA), and 0.82 ± 0.109 (RS-BN). Meanwhile, with leave-one-out (LOO) validation, an average accuracy of 0.98 ± 0.0233 (LOO-SVM), 0.98 ± 0.124 (LOO-LDA), and 0.81 ± 0.109 (LOO-BN) was achieved. Our findings showed that BN was outperformed by SVM and LDA. The promising results of the proposed software pipeline suggest that it may be a valuable tool to support existing clinical diagnosis.

Connectivity measures suggest a sub-cortical generator of myoclonus in Angelman syndrome

OBJECTIVE

The clinical and neurophysiological characteristics of myoclonus in Angelman syndrome (AS) have been evaluated in single case or small cohorts, with contrasting results. We evaluated the features of myoclonus in a wide cohort of AS patients.

METHODS

We performed polygraphic EEG-EMG recording in 24 patients with genetically confirmed AS and myoclonus. Neurophysiological investigations included jerk-locked back-averaging (JLBA), cortico-muscular coherence (CMC) and generalised partial directed coherence (GPDC). CMC and GPDC analyses were compared to those obtained from 10 healthy controls (HC).

RESULTS

Twenty-four patients (aged 3-35 years, median 20) were evaluated. Sequences of quasi-continuous rhythmic jerks mostly occurred at alpha frequency or just below (mean 8.4 ± 1.4 Hz), without EEG correlate. JLBA did not show any clear transient preceding the jerks. CMC showed bilateral over-threshold CMC in alpha band that was prominent on the contralateral hemisphere in the patient group as compared to HC group. GPDC showed a significantly higher alpha outflow from both hemispheres toward activated muscles in the patient group, and a significantly higher beta outflow from contralateral hemisphere in the HC group.

CONCLUSIONS

These neurophysiological findings suggest a subcortical generator of myoclonus in AS.

SIGNIFICANCE

Myoclonus in AS has not a cortical origin as previously hypothesised.

Hypertension, seizures, and epilepsy: a review on pathophysiology and management

BACKGROUND

Epilepsy and hypertension are common chronic conditions, both showing high prevalence in older age groups. This review outlines current experimental and clinical evidence on both direct and indirect role of hypertension in epileptogenesis and discusses the principles of drug treatment in patients with hypertension and epilepsy.

METHODS

We selected English-written articles on epilepsy, hypertension, stroke, and cerebrovascular disease until December, 2018.

RESULTS

Renin-angiotensin system might play a central role in the direct interaction between hypertension and epilepsy, but other mechanisms may be contemplated. Large-artery stroke, small vessel disease and posterior reversible leukoencephalopathy syndrome are hypertension-related brain lesions able to determine epilepsy by indirect mechanisms. The role of hypertension as an independent risk factor for post-stroke epilepsy has not been demonstrated. The role of hypertension-related small vessel disease in adult-onset epilepsy has been demonstrated. Posterior reversible encephalopathy syndrome is an acute condition, often caused by a hypertensive crisis, associated with the occurrence of acute symptomatic seizures. Chronic antiepileptic treatment should consider the risk of drug-drug interactions with antihypertensives.

CONCLUSIONS

Current evidence from preclinical and clinical studies supports the vision that hypertension may be a cause of seizures and epilepsy through direct or indirect mechanisms. In both post-stroke epilepsy and small vessel disease-associated epilepsy, chronic antiepileptic treatment is recommended. In posterior reversible encephalopathy syndrome blood pressure must be rapidly lowered and prompt antiepileptic treatment should be initiated.

Need for a standardized technique of nap EEG recordings: results of a national online survey in Italy

The aim of this study is to report current clinical practice for sleep induction in Italian epilepsy centers. We administered an online-structured survey between March and November 2017 and collected data from pediatric and adult neurophysiologists belonging to 73 epilepsy centers. The preferred time for EEG recording is variable, depending on daily schedule of each laboratory. To facilitate spontaneous sleep during nap EEGs, almost all centers require sleep deprivation before the examination, with partial loss preferred to total deprivation in most centers (58/73 vs 12/73, p < 0.001). Other non-pharmacological procedures include breast/bottle feeding or listening to music (encouraged in most centers). Pharmacological sleep induction is performed in 40% of laboratories, more commonly in children than in adults (27/60 vs 7/42, p = 0.003). Melatonin is the most frequently prescribed drug to facilitate spontaneous sleep (one third of participating centers). Our study highlights the great heterogeneity among Italian epilepsy centers in current clinical practice for sleep EEG recordings. Expert consensus for sleep induction procedure is warranted.

Epileptogenic role of occult temporal encephalomeningocele

Objective

The purpose of this case-control study is to evaluate the prevalence of occult temporal encephalomeningocele (OTE) in patients with temporal lobe epilepsy (TLE) of unknown etiology presenting to an epilepsy center, independently from drug sensitivity.

Methods

We studied 95 patients with TLE (51 female, mean age 49.4 ± 17.1 years) and 151 controls (88 female, mean age 54.1 ± 21.0 years) using a 1.5T brain MRI, including balanced steady-state gradient echo sequences, targeted to the temporal lobes.

Results

OTE was found in 5.2% of the TLE population (9.5% of drug-resistant TLE) and in none of the controls (p = 0.008). Two patients with OTE and drug-resistant TLE became seizure-free after lesionectomy (follow-up 18–24 months).

Conclusion

OTE is not a rare finding in unselected patients with TLE of unknown origin, provided that it is carefully searched. The absence of OTE in a large group of nonepileptic controls adds evidence to its epileptogenic role.

Epilepsy and sleep disorders improve in adolescents and adults with Angelman syndrome: A multicenter study on 46 patients

OBJECTIVE

Actual knowledge on evolution of Angelman syndrome (AS) relies on questionnaire-based cohort studies, phone interviews, or small retrospective cohort studies focused on specific clinical-genetic features. These reports provide conflicting results. The aim of this study was to assess the long-term outcome of epilepsy, sleep disorders, and EEG in a vast series of AS subjects.

METHODS

We collected patients with genetically confirmed AS, aged ≥14years, followed in three tertiary epilepsy Centers or attending the meetings of the Italian Organization for AS (OrSA). Retrospective clinical and EEG data were retrieved from hospital archives or family documents. At index evaluation (IE) (last visit at tertiary Centers or single visit during OrSA meetings), caregivers were interviewed about anamnestic data and filled questionnaires on sleep disorders and daily-living skills. Patients underwent general and neurologic evaluation, and video-EEG recordings. All available EEGs were analyzed to compare evolution of spike-wave index (SWI) over the years.

RESULTS

Forty-six subjects aged 14-45years were included: 24 from tertiary Centers, 22 from OrSA meetings. During childhood, 42/46 (91.3%) had seizures, which improved over the years in all subjects. Among patients with epilepsy, 27(64%) became seizure-free at a median age of 10years and 4 remained seizure-free even after antiepileptic withdrawal. During childhood, 39/46 (84.8%) had sleep disorders, which improved in 27/39 (69%) over the years. At IE, daily-living skills corresponded to age≤1.6years in 29/46 (63%). Electroencephalogram showed typical AS patterns in 35/46 (76.1%). In EEGs recorded from 10 patients, SWI was not significantly different between infancy/childhood and adolescence/adulthood.

CONCLUSION

Improvement of epilepsy or sleep disorders should not disregard the clinical suspicion of AS in adolescent or adult patients with suggestive features. Drug withdrawal might be considered in the management of epilepsy despite the persistence of epileptiform abnormalities.

Methodological issues associated with clinical trials in epilepsy

INTRODUCTION

despite methodological advances in epilepsy clinical trials, the proportion of patients reaching seizure-freedom has not substantially changed over the years. We review the main methodological limitations of current trials, the possible strategies to overcome these limits, and the issues that need to be addressed in next future. Area covered: references were identified by PubMed search until March 2017 and unpublished literature was searched on ClinicalTrials.gov. Add-on trials mainly involve refractory epilepsy subjects, reducing overall response to the investigational drug. The inclusion of subjects with earlier disease from less developed countries has partially allowed overcoming this limitation, but has introduced more random variability of results. Monotherapy trials rise methodological, economical, and ethical concerns with different regulatory requirements in European Union and in the United States of America. Newer trial designs, such as futility trials or 'time-to-event' design, have been implemented. Moreover, both add-on and monotherapy trials results might be affected by patient's ability to recognize and record seizures, and by randomness of seizures occurrence over time. Possible strategies to achieve more reliable outcomes are detailed. Expert commentary: clinical trial methodology needs to be optimized to better address regulatory agencies requirements and to encounter both patients' and clinicians' needs.

Cultural consultation as a model for training multidisciplinary mental healthcare professionals in cultural competence skills: preliminary results

Lack of cultural competence in care contributes to poor experiences and outcomes from care for migrants and racial and ethnic minorities. As a result, health and social care organizations currently promote cultural competence of their workforce as a means of addressing persistent poor experiences and outcomes. At present, there are unsystematic and diverse ways of promoting cultural competence, and their impact on clinician skills and patient outcomes is unknown. We developed and implemented an innovative model, cultural consultation service (CCS), to promote cultural competence of clinicians and directly improve on patient experiences and outcomes from care. CCS model is an adaptation of the McGill model, which uses ethnographic methodology and medical anthropological knowledge. The method and approach not only contributes both to a broader conceptual and dynamic understanding of culture, but also to learning of cultural competence skills by healthcare professionals. The CCS model demonstrates that multidisciplinary workforce can acquire cultural competence skills better through the clinical encounter, as this promotes integration of learning into day-to-day practice. Results indicate that clinicians developed a broader and patient-centred understanding of culture, and gained skills in narrative-based assessment method, management of complexity of care, competing assumptions and expectations, and clinical cultural formulation. Cultural competence is defined as a set of skills, attitudes and practices that enable the healthcare professionals to deliver high-quality interventions to patients from diverse cultural backgrounds. Improving on the cultural competence skills of the workforce has been promoted as a way of reducing ethnic and racial inequalities in service outcomes. Currently, diverse models for training in cultural competence exist, mostly with no evidence of effect. We established an innovative narrative-based cultural consultation service in an inner-city area to work with community mental health services to improve on patients' outcomes and clinicians' cultural competence skills. We targeted 94 clinicians in four mental health service teams in the community. After initial training sessions, we used a cultural consultation model to facilitate 'in vivo' learning. During cultural consultation, we used an ethnographic interview method to assess patients in the presence of referring clinicians. Clinicians' self-reported measure of cultural competence using the Tool for Assessing Cultural Competence Training (n = 28, at follow-up) and evaluation forms (n = 16) filled at the end of each cultural consultation showed improvement in cultural competence skills. We conclude that cultural consultation model is an innovative way of training clinicians in cultural competence skills through a dynamic interactive process of learning within real clinical encounters.

The post-endocytotic fate of the gonadotropin receptors is an important determinant of the desensitization of gonadotropin responses

Internalization of the ligand/receptor complexes is a consequence of the activation of the gonadotropin receptors. Since the recycling or degradation of the internalized receptors results in the maintenance or loss of cell surface receptors respectively and this contributes to the loss of responsiveness, we hypothesized that the fate of the internalized receptors could be an important component of desensitization. We examined this hypothesis using the wild-type and mutants of the human LH (hLHR) receptors and follitropin receptors expressed in MA-10 and KK-1 cells respectively. The receptor mutants were chosen because they are routed mostly to a lysosomal degradation pathway whereas the wild-type receptors are recycled back to the surface. We have shown that agonist stimulation of cells expressing the mutant receptors results in a more pronounced loss of cell surface receptors and agonist responses than stimulation of cells expressing the wild-type receptors. We concluded that receptor recycling promotes the maintenance of cell surface receptors and preserves hormonal responsiveness. This property of the hLHR is likely to be physiologically important because there at least two hLHR-expressing tissues in pregnant women, the maternal corpus luteum and the fetal Leydig cells, where a loss of hormonal responsiveness induced by the elevated levels of human chorionic gonadotropin that occur during pregnancy is not desirable.

Identification of two distinct structural motifs that, when added to the C-terminal tail of the rat LH receptor, redirect the internalized hormone-receptor complex from a degradation to a recycling pathway

We show that most of the internalized rat LH receptor is routed to a lysosomal degradation pathway whereas a substantial portion of the human LH receptor is routed to a recycling pathway. Chimeras of these two receptors identified a linear amino acid sequence (GTALL) present near the C terminus of the human LH receptor that, when grafted onto the rat LH receptor, redirects most of the rat LH receptor to a recycling pathway. Removal of the GTALL sequence from the human LH receptor failed to affect its routing, however. The GTALL sequence shows homology with the C-terminal tetrapeptide (DSLL) of the beta2-adrenergic receptor, a motif that has been reported to mediate the recycling of the internalized beta2-adrenergic receptor by binding to ezrin-radixin-moesin-binding phosphoprotein-50. Addition of the DSLL tetrapeptide to the C terminus of the rat LH receptor also redirects most of the internalized rat LH receptor to a recycling pathway but, like the recycling of the human LH receptor, this rerouting is not mediated by ezrin-radixin-moesin-binding phosphoprotein-50. We conclude that most of the internalized rat LH receptor is degraded because its C-terminal tail lacks motifs that promote recycling and that two distinct, but homologous, motifs (DSLL at the C terminus or GTALL near the C terminus) can reroute the internalized rat LH receptor to a recycling pathway that is independent of ezrin-radixin-moesin-binding phosphoprotein-50.

Mutations of the second extracellular loop of the human lutropin receptor emphasize the importance of receptor activation and de-emphasize the importance of receptor phosphorylation in agonist-induced internalization

Alanine scanning mutagenesis of the second extracellular loop of the human lutropin receptor (hLHR) showed that mutation of most of the residues present in this region either enhance or impair the internalization of agonist. A more complete analysis of four mutants, two that enhanced internalization (F515A and T521A) and two that impaired internalization (S512A and V519A), showed that the two mutants that impaired internalization also show a decrease in the sensitivity for agonist-induced cAMP accumulation, whereas the two mutants that enhanced internalization show an increase in the sensitivity for agonist-induced cAMP accumulation. None of these mutants had an effect on the agonist-induced phosphorylation of the hLHR, however. We conclude that, in contrast to the prevailing view of the relative importance of receptor phosphorylation in the internalization of G protein-coupled receptors, the phosphorylation of the hLHR is less important than the agonist-induced activation of the hLHR in the process of internalization.

Effect of activating and inactivating mutations on the phosphorylation and trafficking of the human lutropin/choriogonadotropin receptor

The effects of several mutations of the human LH receptor (hLHR) on the phosphorylation, internalization, and turnover of the cell surface receptor were examined. Three gain-of-function mutations associated with Leydig cell hyperplasia (L457R and D578Y) and one associated with Leydig cell adenomas (D578H), one signaling-impaired mutation associated with Leydig cell hypoplasia (I625K), and two laboratory designed signaling-impaired mutations (D405N and Y546F) were used. The signaling-impaired mutations showed a reduction in human CG (hCG)-induced receptor phosphorylation and internalization. Mutation of the phosphorylation sites of these loss-of-function mutants had little or no additional effect on internalization. Cotransfection with G protein-coupled receptor kinase-2 (GRK2) rescued the hCG-induced phosphorylation and internalization of the signaling-impaired mutations but only if the phosphorylation sites were intact. Overexpression of arrestin-3 rescued the rate of internalization regardless of whether or not the phosphorylation sites were intact. Only two of the three constitutively active mutants displayed an increase in basal phosphorylation. Although they all failed to respond to hCG with increased receptor phosphorylation, they all internalized hCG faster than wild-type hLHR (hLHR-wt). Mutation of the phosphorylation sites of these constitutively active mutants lengthened the half-time of internalization of hCG toward that of hLHR-wt. Overexpression of arrestin-3 had little or no effect on the already short half-time of internalization of hCG mediated by these mutants. The data obtained with the signaling-impaired and phosphorylation-deficient mutants of the hLHR support a model whereby receptor phosphorylation and activation play a redundant role in the internalization of hCG. The results obtained with the constitutively active mutants suggest that, when occupied by hCG, these mutants assume a conformation that bypasses many of the steps (i.e. activation, phosphorylation, and/or arrestin binding) involved in internalization.

Multiple distant amino acid residues present in the serpentine region of the follitropin receptor modulate the rate of agonist-induced internalization

The amino acid sequences of the human (h) and rat (r) follitropin receptors (FSHR) are approximately 89% identical, but the half-time of internalization of agonist mediated by the rFSHR is approximately 3 times faster than that of the hFSHR. Chimeras of the hFSHR and the rFSHR showed that this difference in rate is dictated mostly by the serpentine domain. Further analysis identified six residues, two non-contiguous residues in the transmembrane helix 4 (Leu/Thr in the rFSHR and Met/Ile in the hFSHR), three non-contiguous residues in the third intracellular loop (Thr/Thr/Lys in the rFSHR and Ile/Asn/Arg in the hFSHR), and one in transmembrane helix 7 (Tyr in the rFSHR and His in the hFSHR) that are fully responsible for the difference in the rates of internalization of the hFSHR and the rFSHR.

The C-terminal tail of the rat lutropin/choriogonadotropin (CG) receptor independently modulates human (h)CG-induced internalization of the cell surface receptor and the lysosomal targeting of the internalized hCG-receptor complex

The analysis of 21 progressive truncations of the C-terminal tail of the rat LH/CG receptor (rLHR) revealed the presence of a region delineated by residues 628-649 that, when removed, enhanced the degradation of the internalized human (h)CG. The analysis of these truncations also revealed the presence of a region delineated by residues 624-631 that, when removed, enhanced the rate of internalization of hCG. Since there is little overlap between these two regions, we conclude that the structural features of the rLHR that mediate internalization and degradation of the internalized hormone are different. Detailed analyses of cells expressing a truncation at Y637 (designated rLHR-t637) showed that the enhanced degradation of hCG observed in the these cells is due to an increase in the rate of transfer of the internalized hCG-rLHR complex from the endosomes to the lysosomes rather than to the enhanced dissociation of the hCG-rLHR complex in the lysosomes.

p38JAB1 binds to the intracellular precursor of the lutropin/choriogonadotropin receptor and promotes its degradation

Using the C-terminal tail of the rat lutropin/choriogonadotropin receptor (rLHR) as "bait" in a yeast two-hybrid screen resulted in the identification of p38(JAB1) (a protein initially identified as a co-activator of c-Jun) as a putative rLHR binding partner. More recently p38(JAB1) has been shown to promote the degradation of a cyclin-dependent kinase inhibitor and to be a component of the COP9 signalosome. Microscopic localization of an epitope-tagged p38(JAB1) expressed in 293 cells revealed a punctuated perinuclear and cytosolic localization, while cell fractionation studies showed that most of the p38(JAB1) was in a high speed supernatant. Co-transfection of 293 cells revealed that p38(JAB1) binds to the immature 68-kDa precursor of the rLHR that resides in the endoplasmic reticulum and promotes its degradation. It does not appear to interact with the cell surface rLHR, however, and it does not affect its expression. When transfected into HeLa cells, p38(JAB1) potentiates the transcriptional activity of c-Jun, but co-transfection with rLHR prevents this effect. We conclude that p38(JAB1) interacts with the rLHR precursor and promotes its degradation. These results reveal a novel protein binding partner of the rLHR and are consistent with current views of the functions of p38(JAB1).

Seven non-contiguous intracellular residues of the lutropin/choriogonadotropin receptor dictate the rate of agonist-induced internalization and its sensitivity to non-visual arrestins

The amino acid sequences of the human (h) and rat (r) lutropin/choriogonadotropin receptors (LHR) are 87% identical, but the rate of agonist-induced internalization of the hLHR is approximately 7 times faster than that of the rLHR. Chimeras of the hLHR and the rLHR showed that this rate is dictated by the serpentine domain and the cytoplasmic tail. Further mutational analysis identified seven residues, two adjacent residues in the second intracellular loop (Val/Gln in the rLHR and Ile/His in the hLHR), four non-contiguous residues in the third intracellular loop (Arg/Gln/Thr/Pro in the rLHR and Lys/Arg/Met/Thr in the hLHR), and one in the C-terminal tail (Leu in the rLHR and Phe in the hLHR), that are necessary and sufficient to impart the slow rate of internalization of the rLHR and the fast rate of internalization of the hLHR. The internalization of the rLHR and the hLHR display different sensitivities to the non-visual arrestins. Therefore, we also tested if the simultaneous exchange of these seven residues resulted in the exchange of this property. Since this was found to be the case, we propose that these seven residues identified here form a non-visual arrestin-binding site.

A dileucine-based motif in the C-terminal tail of the lutropin/choriogonadotropin receptor inhibits endocytosis of the agonist-receptor complex

The rat lutropin/choriogonadotropin receptor (rLHR) is a member of the rhodopsin-like subfamily of G protein-coupled receptors that has two adjacent dileucine motifs in the C-terminal cytoplasmic tail. Here we show that simultaneous (L613,614,615,616A) or individual (L613,L614A or L615,616A) mutation of the two adjacent dileucine motifs to alanines results in mutants with enhanced rates of agonist-induced internalization. The L613,L614A mutation was much more effective in enhancing internalization than the L615,L616A mutation. Moreover, the L613A mutation was more effective than the L614A mutation. Because in the human LHR the residues equivalent to L613 and L614 of the rLHR are a phenylalanine and a leucine (F635 and L636), we also prepared mutants that exchanged these motifs. In the rLHR, an LL-to-FL exchange enhanced endocytosis, and in the human LHR, an FL-to-LL exchange impaired endocytosis. The internalization of rLHR-wt and rLRH-L613,L614A was inhibited by coexpression of the clathrin-binding domain of beta-arrestin. In fact, this manipulation reduced the enhanced rate of internalization of rLHR-L613,614A back to that of rLHR-wt. The L613,614A mutation does not affect the degradation of the internalized agonist or the membrane targeting of the nascent rLHR. The L615,616A mutation also did not affect degradation of the internalized agonist but impaired the membrane targeting of the nascent rLHR. We conclude that the dileucine-based motifs of the rLHR inhibit internalization and suggest that this inhibition may be due to an impairment in the binding of the rLHR to endogenous nonvisual arrestins.

The rate of internalization of the gonadotropin receptors is greatly affected by the origin of the extracellular domain

Previous results from this laboratory have shown that human kidney (293) cells transfected with the rat follitropin receptor (rFSHR) internalize agonist (i.e. human follitropin, hFSH) at a rate similar to that of other agonist-G protein-coupled receptor complexes while 293 cells transfected with the rat lutropin/choriogonadotropin receptor (rLHR) internalize agonist (human choriogonadotropin, hCG) at a rate that is about 1 order of magnitude slower. Taking advantage of this difference and the high degree of homology between the rLHR and rFSHR, we have now used chimeras of these two receptors to begin to delineate structural features that influence their internalization. Analysis of six chimeras that exchanged only the transmembrane domains (designated FLF and LFL), only the COOH-terminal domains (FFL or LLF) or both domains (FLL or LFF) show that the origin of the extracellular domain is at least as important, if not more, than the origin of the transmembrane and COOH-terminal domains in determining the rate of internalization of the gonadotropin receptors. Thus, the rates of internalization of agonist internalization mediated by FFL, FLF, and FLL more closely resemble rFSHR than rLHR, while the rates of agonist internalization mediated by LLF, LFL, and LFF more closely resemble rLHR than rFSHR. The importance of the extracellular domain was also evident even upon overexpression of arrestin-3, a protein that enhances the rate of internalization of the wild-type receptors and chimeras by binding to their intracellular regions.

Role of the rate of internalization of the agonist-receptor complex on the agonist-induced down-regulation of the lutropin/choriogonadotropin receptor

The extent of agonist-induced down-regulation of the LH/CG receptor (LHR) in human kidney 293 cells transfected with the rat LHR (rLHR) is much lower than in two Leydig tumor cell lines (MA-10 and R2C) that express the rodent LHR endogenously. This difference can not be attributed to differences in the recycling of internalized receptors, or in the replenishment of new receptors at the cell surface. It can be correlated, however, with the half-life of internalization of the bound agonist, which is approximately 60 min in Leydig tumor cells and about 100 min in transfected 293 cells. To determine whether the rate of internalization of the bound agonist affects down-regulation, we compared these two parameters in 293 cells expressing four rLHR mutants that enhance internalization and three mutants that impair internalization. We show that all four mutations of the rLHR that enhanced internalization enhanced down-regulation, while only one of the three mutations that impaired internalization impaired down-regulation. In addition, cotransfections of 293 cells with the rLHR-wt and three constructs that enhanced internalization (G protein-coupled receptor kinase 2, beta-arrestin, and arrestin-3) increased down-regulation, while a related construct (visual arrestin) that had no effect on internalization also had no effect on down-regulation. We conclude that the rate of internalization of the agonist-LHR complex is the main determinant of the extent of down-regulation of the LHR.

Comparative in-vitro activity of levofloxacin against isolates of bacteria from adult patients with community-acquired lower respiratory tract infections

This study was conducted to evaluate the activity of levofloxacin in comparison with a range of antibacterial agents against recent isolates obtained consecutively from patients with community-acquired pneumonia (CAP) or acute exacerbation of chronic bronchitis (AECB) during the period 1995 to 1996. Susceptibility testing was carried out by either microdilution or the Etest, and interpreted according to NCCLS breakpoints. The activity of levofloxacin was compared with that of amoxycillin, amoxycillin-clavulanate, cefuroxime, cefixime, erythromycin, roxithromycin, clarithromycin, azithromycin, ofloxacin and ciprofloxacin. Clinically significant numbers of bacteria were recovered from 31 CAP and 94 AECB specimens. The predominant bacterial species in the CAP specimens were Streptococcus pneumoniae (21 isolates) and Haemophilus influenzae (four isolates). The AECB isolates mainly consisted of S. pneumoniae (38%), Moraxella catarrhalis (26%), H. influenzae (19%) and Pseudomonas aeruginosa (10%). The overall percentage susceptible of the isolates for each antibiotic was: amoxycillin, 64%; amoxycillin-clavulanate, 89%; cefuroxime, 87%; cefixime, 78%; erythromycin, 85%; roxithromycin, 87%; clarithromycin, 87%; azithromycin, 85%; ofloxacin, 95%; ciprofloxacin, 95%; and levofloxacin, 97%. The activities of levofloxacin and the other agents were also compared against 40 S. pneumoniae isolates, of which 20 were penicillin-non-susceptible, recovered from CAP and AECB specimens during the period 1994 to 1996. These strains were all susceptible to levofloxacin, but only 50% were susceptible to ciprofloxacin and 80% to ofloxacin. Twenty M. catarrhalis, 20 H. influenzae and 20 methicillin-susceptible S. aureus isolates were also all susceptible to levofloxacin. Furthermore, 20 community-acquired P. aeruginosa isolates showed similar percentage susceptible rates to levofloxacin and ciprofloxacin. These in-vitro results suggest that levofloxacin may be useful in the treatment of community-acquired lower respiratory tract infections.

Role of G protein-coupled receptor kinases on the agonist-induced phosphorylation and internalization of the follitropin receptor

The experiments presented herein were designed to identify members of the G protein-coupled receptor kinase (GRK) family that participate in the agonist-induced phosphorylation and internalization of the rat FSH receptor (rFSHR). Western blots of human kidney 293 cells (the cell line used in transfection experiments) and MSC-1 cells (a cell line derived from Sertoli cells that displays many of the differentiated functions of their normal counterparts) reveal the presence of GRK2 and GRK6 in both cell lines as well as GRK4 in MSC-1 cells. Cotransfection of 293 cells with the rFSHR and GRK2, GRK4alpha, or GRK6 resulted in an increase in the agonist-induced phosphorylation of the rFSHR. Cotransfections of the rFSHR with GRKs or arrestin-3 enhanced the agonist-induced internalization of the rFHSR, and combinations of GRKs and arrestin-3 were more effective than the individual components. To characterize the involvement of endogenous GRKs on phosphorylation and internalization, we inhibited endogenous GRK2 by overexpression of a kinase-deficient mutant of GRK2 or G alpha t, a scavenger of G betagamma. We also inhibited endogenous GRK6 by overexpression of a kinase-deficient mutant of GKR6. All three constructs were effective inhibitors of phosphorylation, but only the kinase-deficient mutant of GRK2 and G alpha t inhibited internalization. The inhibition of internalization induced by these two constructs was less pronounced than that induced by a dominant-negative mutant of the nonvisual arrrestins, however. The finding that inhibitors of GRK2 and GRK6 impair phosphorylation, but only the inhibitors of GRK2 impair internalization, suggests that different GRKs have differential effects on receptor internalization.

Mutations that induce constitutive activation and mutations that impair signal transduction modulate the basal and/or agonist-stimulated internalization of the Lutropin/Choriogonadotropin receptor

Previous results from this laboratory suggested that the same active conformation of the lutropin/choriogonadotropin receptor (LHR) is involved in the stimulation of G proteins and in triggering the internalization of the bound agonist. We have now analyzed two naturally occurring, constitutively active mutants of the human LHR. These mutations were introduced into the rat LHR (rLHR) and are designated L435R and D556Y. Cells expressing rLHR-D556Y bind human choriogonadotropin (hCG) with normal affinity, exhibit a 25-fold increase in basal cAMP and respond to hCG with a normal increase in cAMP accumulation. This mutation does not affect the internalization of the free receptor, but it enhances the internalization of the agonist-occupied receptors approximately 3-fold. Cells expressing rLHR-L435R also bind hCG with normal affinity, exhibit a 47-fold increase in basal cAMP, and do not respond to hCG with a further increase in cAMP accumulation. This mutation enhances the internalization of the free and agonist-occupied receptors approximately 2- and approximately 17-fold, respectively. We conclude that the state of activation of the rLHR can modulate its basal and/or agonist-stimulated internalization. Since the internalization of hCG is involved in the termination of hCG actions, we suggest that the lack of responsiveness detected in cells expressing rLHR-L435R is due to the fast rate of internalization of the bound hCG. The finding that membranes expressing rLHR-L435R (a system where internalization does not occur) respond to hCG with an increase in adenylyl cyclase activity supports this suggestion.

Signaling and phosphorylation-impaired mutants of the rat follitropin receptor reveal an activation- and phosphorylation-independent but arrestin-dependent pathway for internalization

We have previously shown that the rat follitropin receptor (rFSHR) expressed in transfected cells becomes phosphorylated upon stimulation of the cells with agonist or a phorbol ester. Peptide mapping and mutagenesis studies have also shown that the agonist- or phorbol ester-induced phosphorylation of the rFSHR maps to Ser/Thr residues present in the first and third intracellular loops. The experiments presented herein were initially designed to test for the presence of additional phosphorylation sites on the second intracellular loop of the rFSHR. Analysis of two new mutants in which the two threonines in the second intracellular loop (rFSHR-2L) or the two threonines in the second intracellular loop and the seven Ser/Thr residues in the third intracellular loop (rFSHR-2L + 3L) were mutated showed that one or more of the two threonines in the second intracellular loop are phosphorylated in response to phorbol ester, but not in response to agonist stimulation. Since rFSHR-2L and rFSHR-2L + 3L displayed a reduction in agonist-induced signaling, two additional mutants (rFSHR-D389N and rFSHR-Y530F) were constructed in an attempt to better understand the relationship between the agonist-induced activation, phosphorylation, and internalization of the rFSHR. These point mutations impaired agonist-stimulated signal transduction and abolished agonist-induced phosphorylation. Co-transfection studies revealed that the phosphorylation of these mutants can be rescued by overexpression of G protein-coupled receptor kinase 2, but this increased phosphorylation only rescues the internalization of rFSHR-D389N. The internalization of both mutants could be rescued by overexpression of arrestin-3, however. Taken together, these results argue that the agonist-induced activation and phosphorylation of the rFSHR are not essential for internalization. while the interaction of the rFSHR with a nonvisual arrestin is essential for internalization.

Mutation of individual serine residues in the C-terminal tail of the lutropin/choriogonadotropin receptor reveal distinct structural requirements for agonist-induced uncoupling and agonist-induced internalization

We have previously mapped the agonist-induced phosphorylation of the rat lutropin/choriogonadotropin receptor (rLHR) to a locus of four serines (Ser635, Ser639, Ser649, and Ser652) located in the C-terminal tail. The removal or mutation of this locus delays the time course of agonist-induced uncoupling of the rLHR from its effector system without affecting the overall magnitude of uncoupling, and it retards the endocytosis of the agonist-receptor complex. We have now prepared and analyzed four new rLHR mutants in which each of these serines were individually mutated to alanines. The data presented show that each mutation reduces agonist-promoted rLHR phosphorylation by 20-40%. Mutation of Ser635 or Ser639 delayed the time course of agonist-induced uncoupling to about the same extent as the simultaneous mutation of all four serines. Mutation of Ser635 or Ser639 also retarded agonist-induced internalization, but the magnitude of this decrease was less than that induced by the simultaneous mutation of all four serines. Mutation of Ser649 had no effect on agonist-induced uncoupling but retarded agonist-induced internalization to the same extent as the simultaneous mutation of all four serines. Mutation of Ser652 has little or no effect on either of these two parameters. Co-transfection studies with dominant-negative arrestins and dominant-negative dynamin reveal that, despite differences in their rates of internalization, rLHR-wild-type, rLHR-S639A, and rLHR-S649A are internalized by an arrestin- and dynamin-dependent pathway. These data show that the structural requirements needed for the agonist-induced uncoupling and internalization of the rLHR are distinct.

The agonist-induced phosphorylation of the rat follitropin receptor maps to the first and third intracellular loops

Previous results from this laboratory have shown that the rat FSH receptor (rFSHR) becomes phosphorylated on S/T residues upon stimulation of transfected cells with human (h)FSH and that a truncation of the C-terminal tail that removes 12 of the 25 intracellular S/T residues does not affect phosphorylation. Based on the results of phosphopeptide-mapping experiments we analyzed three new mutants. rFSHR-1L and rFSHR-3L were constructed by mutating the S/T residues in the first intracellular loop or the third intracellular loop, respectively. rFSHR-(3L+CT) was constructed by mutating all the S/T residues in the third loop as well as S624, the only C-terminal tail residue that was not previously eliminated as a potential phosphorylation site. All mutants were biologically active. The agonist-induced phosphorylation of rFSHR-3L and rFSHR-(3L+CT) were partially reduced, while that of rFSHR-1L was almost completely lost. The agonist-induced uncoupling of rFSHR-1L and rFSHR-3L are retarded to about the same extent, while the agonist-induced internalization is retarded only in rFSHR-1L. Four major conclusions can be made from the present studies: 1) the phosphorylated rFSHR is a common molecular intermediate in agonist-induced uncoupling and internalization; 2) agonist-induced phosphorylation of the rFSHR maps to the first and third intracellular loops; 3) the phosphorylation of the third intracellular loop facilitates agonist-induced uncoupling but is not necessary for agonist-induced internalization; 4) agonist-induced internalization is facilitated by phosphorylation but it is not known if only the first loop, only the third loop, or both the first and third loops need to be phosphorylated for this response.

Transfected cells express mostly the intracellular precursor of the lutropin/choriogonadotropin receptor but this precursor binds choriogonadotropin with high affinity

Previous studies from several laboratories have shown that the cell surface rLHR is a 85-92 kDa protein synthesized from a 68-73 kDa intracellular precursor. While all investigators agree that the cell surface rLHR binds hCG with high affinity, it is not clear if the intracellular precursor can also bind hCG. In order to directly determine if the intracellular rLHR present in cells transfected with the wild-type rLHR binds hCG with high affinity, we devised a method that selectively degrades the cell surface rLHR while preserving the intracellular rLHR. The binding of hCG to intact cells was completely lost following mild proteolysis of the cells, but binding to detergent extracts prepared from proteolyzed cells was largely preserved. Measurements of the hCG binding affinity to intact cells or to detergent extracts prepared before and after proteolysis display very similar or identical binding affinities. Since binding to nonproteolyzed intact cells, detergent extracts prepared from nonproteolyzed cells, or detergent extracts prepared from proteolyzed cells occurs only to the 85-92 kDa rLHR, the 85-92 and 68-73 kDa rLHR, and the 68-73 kDa rLHR, respectively, we conclude that the cell surface rLHR and the intracellular rLHR bind hCG with the same affinity. Quantitation of the relative abundance of the cell surface and intracellular rLHR by immunological methods indicates that transfected cells express mostly the intracellular precursor. A comparison of the binding capacity of control and proteolyzed cells with that of their detergent extracts indicates that hCG binding assays greatly underestimate the relative abundance of the intracellular rLHR.

Molecular basis of the regulation of the lutropin/choriogonadotropin receptor

The studies summarized here clearly show that the phosphorylation of one or more serine residues (S635, S639, S649 and/or S652) present in the C-terminal tail of the LHR is necessary, but not sufficient, for the agonist-induced uncoupling of the LHR from adenylate cyclase and for the endocytosis of the agonist-receptor complex. Simultaneous mutation of these four serines to alanines decreases the rate of agonist-induced uncoupling and the rate of agonist-induced internalization. This mutation does not affect the magnitude of agonist-induced uncoupling attained upon a long incubation with agonist, nor does it reduce the rate of internalization of the agonist-bound LHR to that of the free LHR. Thus additional molecular interactions and/or post-translational modifications of the LHR are needed for uncoupling and down-regulation.

Phosphorylation of the lutropin/choriogonadotropin receptor facilitates uncoupling of the receptor from adenylyl cyclase and endocytosis of the bound hormone

Stably transfected cell lines expressing the wild-type rat LH/CG receptor (rLHR) or a full-length rLHR in which S635, T638, S639, S649 and S653 were simultaneously mutated to alanine residues (designated rLHR-5S/T-->A) were used to probe the importance of receptor phosphorylation on the regulation of receptor functions. The mutant receptor binds hCG with high affinity and transduces the hormonal signal into increases in cAMP and inositol phosphate accumulation comparable in magnitude to those elicited by the wild-type receptor. In contrast to cells expressing rLHR-wt, which respond to hCG or phorbol 12-myristate 13-acetate stimulation with an increase in rLHR phosphorylation, the phosphorylation of rLHR in cells expressing rLHR-5S/T-->A is severely blunted. Likewise, the phorbol 12-myristate 13-acetate-induced desensitization of hCG-induced cAMP accumulation is drastically reduced in cells expressing rLHR-5S/T-->A. In contrast, the hCG-induced desensitization of hCG-induced cAMP accumulation is delayed, but not abolished, in cells expressing rLHR-5S/T-->A. Lastly, the rate of internalization of the receptor-bound hCG is slower in cells expressing rLHR-5S/T-->A than in cells expressing rLHR-wt. These results show that phosphorylation of rLHR is necessary, but not sufficient, for uncoupling of the receptor from adenylyl cyclase and for endocytosis of the receptor-bound hormone.

Functional consequences of the phosphorylation of the gonadotropin receptors

When target cells are exposed to a hormone, their responsiveness wanes with time, in spite of the continuous presence of the hormone. This phenomenon, referred to as desensitization, is due to regulatory steps that occur at the level of the hormone receptor as well as at post-receptor steps. While post-receptor events may be specific for the metabolic pathways activated in a given target cell, receptor events are more general in nature and conserved within a given family of receptors. There are at least two categories of regulatory events that occur at the level of the receptor and contribute to the process of desensitization. One of them, referred to as receptor uncoupling, will be used here to denote a change in the functional properties of a constant number of receptors resulting in a reduction in the ability of the receptor to activate its most proximal effector system. The other, referred to as receptor down-regulation, will be used here to denote a reduction in the density of cell surface receptors. Uncoupling is generally faster than down-regulation, and is believed to be due to post-translational modifications of the receptor. Down-regulation, on the other hand, is slower, and could be due to an increase in the rate of receptor internalization, sequestration or degradation, and/or to a decrease in the rate of receptor externalization, processing or synthesis. In this paper, recent studies from my laboratory designed to directly address the potential involvement of gonadotropin receptor phosphorylation in the process of uncoupling have been reviewed.