Management of vagus nerve stimulation therapy in the peri-operative period: Guidelines from the Association of Anaesthetists: Guidelines from the Association of Anaesthetists.

Vagus nerve stimulation is a well-established treatment option for patients with drug-resistant epilepsy and has an expanding range of other clinical indications. Side effects of vagus nerve stimulation therapy include: cough; voice changes; vocal cord adduction; rarely, obstructive sleep apnoea; and arrhythmia. Patients with implanted vagus nerve stimulation devices may present for unrelated surgery and critical care to clinicians who are unfamiliar with their function and safe management. These guidelines have been formulated by multidisciplinary consensus based on case reports, case series and expert opinion to support clinicians in the management of patients with these devices. The aim is to provide specific guidance on the management of vagus nerve stimulation devices in the following scenarios: the peri-operative period; peripartum period; during critical illness; and in the MRI suite. Patients should be aware of the importance of carrying their personal vagus nerve stimulation device magnet with them at all times to facilitate urgent device deactivation if necessary. We advise that it is generally safer to formally deactivate vagus nerve stimulation devices before general and spinal anaesthesia. During periods of critical illness associated with haemodynamic instability, we also advise cessation of vagus nerve stimulation and early consultation with neurology services.

Age differences in the association of comorbid burden with adverse outcomes in SARS-CoV-2.

BACKGROUND: Older age and comorbid burden are both associated with adverse outcomes in SARS-CoV-2, but it is not known whether the association between comorbid burden and adverse outcomes differs in older and younger adults. OBJECTIVE: To compare the relationship between comorbid burden and adverse outcomes in adults with SARS-CoV-2 of different ages (18-64, 65-79 and ≥ 80 years). DESIGN, SETTING, AND PARTICIPANTS: Observational longitudinal cohort study of 170,528 patients who tested positive for SARS-CoV-2 in the US Department of Veterans Affairs (VA) Health Care System between 2/28/20 and 12/31/2020 who were followed through 01/31/2021. MEASUREMENTS: Charlson Comorbidity Index (CCI); Incidence of hospitalization, intensive care unit (ICU) admission, mechanical ventilation, and death within 30 days of a positive SARS-CoV-2 test. RESULTS: The cumulative 30-day incidence of death was 0.8% in cohort members < 65 years, 7.1% in those aged 65-79 years and 20.6% in those aged ≥80 years. The respective 30-day incidences of hospitalization were 8.2, 21.7 and 29.5%, of ICU admission were 2.7, 8.6, and 11% and of mechanical ventilation were 1, 3.9 and 3.2%. Median CCI (interquartile range) ranged from 0.0 (0.0, 2.0) in the youngest, to 4 (2.0, 7.0) in the oldest age group. The adjusted association of CCI with all outcomes was attenuated at older ages such that the threshold level of CCI above which the risk for each outcome exceeded the reference group (1st quartile) was lower in younger than in older cohort members (p < 0.001 for all age group interactions). LIMITATIONS: The CCI is calculated based on diagnostic codes, which may not provide an accurate assessment of comorbid burden. CONCLUSIONS: Age differences in the distribution and prognostic significance of overall comorbid burden could inform clinical management, vaccination prioritization and population health during the pandemic and argue for more work to understand the role of age and comorbidity in shaping the care of hospitalized patients with SARS-CoV-2.

Review of external referrals to a regional stroke centre: it is not just about thrombectomy.

AIMS: To determine the experience of a regional stroke referral centre of external referrals for endovascular thrombectomy (EVT) in patients with symptoms of acute ischaemic stroke (AIS) and large vessel occlusion (LVO). MATERIALS AND METHODS: Data were collected prospectively over two 4-month periods (2017-2018) on consecutive external referrals for EVT. Baseline demographics, imaging findings, and key time parameters were recorded. Reasons for not transferring patients and for not performing EVT were recorded. Key time intervals were calculated and compared between the transferred and non-transferred group with and without intracranial occlusion and between the transferred patients who underwent thrombectomy and those who did not. RESULTS: Two hundred and sixty-two patients were referred. Sixty-one percent (n=159) were accepted and transferred for treatment. Of those transferred, 86% (n=136) had EVT. Fourteen percent (n=23) were unsuitable for EVT on arrival due to no vessel occlusion (48% n=11), poor Alberta Stroke Program Early CT Score (ASPECTS)/established infarct (30%, n=7) haemorrhage (9%, n=2), and clinical recovery (13% n=3). One hundred and three patients (39%) were ineligible for EVT following phone discussion due to absence of intracranial occlusion (59%, n=61), low ASPECTS (22%, n=23), distal occlusion (4%, n=4), low/improving National Institutes of Health Stroke Scale (NIHSS; 10.7%, n=11), and poor modified Rankin Scale (mRS) at baseline (3%, n=3). Patients with LVO but not transferred had longer onset to hospital arrival time compared with those transferred 151.5 versus 91 minutes (p<0.005), with a trend also toward a longer door to CT/CTA 40 minutes versus 30 minutes (p=0.142). CONCLUSION: These data provide valuable insights into the service provision of a comprehensive stroke network. The present rates of EVT and futile transfers are modest compared to published data. Access to neuroradiology and specialised stroke assessment is crucial to optimise time to treatment.

Neuroimaging of central diabetes insipidus-when, how and findings.

Central or neurogenic diabetes insipidus (CDI) is due to deficient synthesis or secretion of antidiuretic hormone (ADH), also known as arginine vasopressin peptide (AVP). It is clinically characterised by polydipsia and polyuria (urine output > 30 mL/kg/day) of dilute urine (< 250 mOsm/L). It is the result of a defect in one of more sites involving the hypothalamic osmoreceptors, supraoptic or paraventricular nuclei of the hypothalamus, median eminence of the hypothalamus, infundibulum or the posterior pituitary gland. A focused MRI pituitary gland or sella protocol is essential. There are several neuroimaging correlates and causes of CDI, illustrated in this review. The most common causes are benign or malignant neoplasms of the hypothalamic-pituitary axis (25%), surgery (20%), head trauma (16%) or familial causes (10%). No cause is identified in up to 30% of cases. Knowledge of the anatomy and physiology of the hypothalamo-neurohypophyseal axis is crucial when evaluating a patient with CDI. Establishing the aetiology of CDI with MRI in combination with clinical and biochemical assessment facilitates appropriate targeted treatment. The aim of the pictorial review is to illustrate the wide variety of causes of CDI on neuroimaging, highlight the optimal MRI protocol and to revise the detailed neuroanatomy and neurophysiology required to interpret these studies.

Exercise Rehabilitation Services Provided by Physiotherapy Departments in Cancer Care in Ireland

Aims This study aimed to identify the physiotherapy exercise rehabilitation services available to patients with cancer in Ireland and to identify barriers to the provision of services. Methods Physiotherapy department managers in specialised cancer centres, public and private hospitals and palliative care settings were surveyed to establish the availability of exercise rehabilitation services for patients with cancer. Results Of 40 managers contacted, 24 responded providing information about 26 services. Ten services employed a dedicated oncology physiotherapist. Exercise classes were offered to patients with cancer by five services, primarily within the palliative care setting. In the 17 hospitals which provided surgery, ten provided oncology specific post-operative exercise rehabilitation and one offered a prehabilitation programme. Limited human and physical resources and absence of established physiotherapy pathways were cited barriers to service provision. Conclusion Exercise rehabilitation is not an element of standard care for patients with cancer in Ireland.

Outcomes of endovascular treatment for acute large-vessel ischaemic stroke more than 6 h after symptom onset.

BACKGROUND AND OBJECTIVES: Benefit from endovascular thrombectomy (EVT) for large-vessel occlusion (LVO) acute ischaemic stroke (AIS) is well demonstrated. Furthermore, emerging evidence supports efficacy in appropriately selected patients treated beyond current recommendations of 6 h. We evaluated clinical outcomes in patients undergoing late EVT at our institution. METHODS: Retrospective review of prospectively collected clinical database on 355 patients who underwent EVT for LVO AIS. Data collected consisted of patient demographics, radiological findings and outcome details. Outcomes, including 90-day functional status, recanalization, symptomatic intracranial haemorrhage (sICH) and 90-day mortality, for patients undergoing EVT <6 h, >6 h, and >7.3 h, were compared. RESULTS: A total of 355 patients underwent EVT for LVO AIS at our institution during the review period, with 74 (21%) patients treated ≥6 h from symptom onset. Successful recanalization was achieved in 285 (80%) patients, with 228 (81%) achieving a mTICI ≥2b in the <6 h group, and 57 (77%) in the >6 h group (P = 0.429). Ninety-day functional independence (mRS 0-2) was achieved in 162 (46%) patients, with 130 (46%) achieving a mRS of 0-2 in the <6 h group, and 32 (43%) in the >6 h group (P = 0.643). No significant differences were found in rates of sICH or 90-day mortality. No significant differences in functional independence, recanalization rates, sICH or mortality were identified in patients treated with EVT >7.3 h compared to <7.3 h. CONCLUSIONS: In appropriately selected patients, EVT >6 h was associated with comparable outcomes to those treated <6 h. These data support a physiological approach to patient selection.

Double Stent-Retriever Technique in Endovascular Treatment of Middle Cerebral Artery Saddle Embolus.

Ischemic stroke is a major public health problem worldwide, considered as the third most costly health condition in developed countries, with urgent reperfusion remaining the paramount goal for its treatment. In line with the results of recent randomized control trials, the introduction of stent retrievers was a major advancement in the treatment of stroke; however, interventionalists sometimes encounter thrombi not-retrievable by applying conventional techniques. In this article, we present a case treated by an innovative double-stent retrieval in Y-configuration that may potentially help other clinicians in similar situations.

Endovascular treatment for acute ischaemic stroke with large vessel occlusion: the experience of a regional stroke service.

AIM: To report the experience of a regional stroke referral service with endovascular treatment for patients with acute ischaemic stroke (AIS) and large vessel occlusion. MATERIALS AND METHODS: A prospective review was undertaken of 93 consecutive cases receiving endovascular treatment for AIS over a 42-month period (January 2010 to June 2013). The National Institutes of Health Stroke Scale (NIHSS), location of large vessel occlusion, details of endovascular procedure, and degree of reperfusion achieved (Thrombolysis In Cerebral Infarction [TICI] score) were recorded. Mortality and functional outcome (modified Rankin Scale [mRS]) were measured at 90 days. RESULTS: The mean patient age was 62 years (range 26-87 years). The mean NIHSS at presentation was 16 (range 6-29). All patients had confirmed proximal large-artery occlusion on computed tomography (CT) angiography: 87 in the anterior circulation, six in the posterior circulation. Of the 93 patients treated, 64 (69%) received intravenous thrombolysis. Successful reperfusion (TICI grade 2a to 3) was achieved in 80 (86%) cases. There were 13 (14%) cases of failed vessel recanalisation (TICI grade 0). Good functional outcome (mRS ≤2) was achieved in 51 (55%) cases. The 90-day mortality was 20 (22%) cases. Fifty-seven (61%) cases were transferred from outside centres. There was no significant increase in morbidity or mortality for transferred patients. CONCLUSION: Successful endovascular recanalisation can result in good functional outcomes for patients with AIS and large vessel occlusion. Our interventional neuroradiology service provides endovascular treatment as part of a regional stroke service without increase in morbidity or mortality for patients transferred from outside institutions.

Estimating epidemiological parameters for bovine tuberculosis in British cattle using a Bayesian partial-likelihood approach.

Fitting models with Bayesian likelihood-based parameter inference is becoming increasingly important in infectious disease epidemiology. Detailed datasets present the opportunity to identify subsets of these data that capture important characteristics of the underlying epidemiology. One such dataset describes the epidemic of bovine tuberculosis (bTB) in British cattle, which is also an important exemplar of a disease with a wildlife reservoir (the Eurasian badger). Here, we evaluate a set of nested dynamic models of bTB transmission, including individual- and herd-level transmission heterogeneity and assuming minimal prior knowledge of the transmission and diagnostic test parameters. We performed a likelihood-based bootstrapping operation on the model to infer parameters based only on the recorded numbers of cattle testing positive for bTB at the start of each herd outbreak considering high- and low-risk areas separately. Models without herd heterogeneity are preferred in both areas though there is some evidence for super-spreading cattle. Similar to previous studies, we found low test sensitivities and high within-herd basic reproduction numbers (R0), suggesting that there may be many unobserved infections in cattle, even though the current testing regime is sufficient to control within-herd epidemics in most cases. Compared with other, more data-heavy approaches, the summary data used in our approach are easily collected, making our approach attractive for other systems.

Developing a framework for risk-based surveillance of tuberculosis in cattle: a case study of its application in Scotland.

Due to its substantially lower prevalence of bovine tuberculosis (bTB) relative to other areas of Great Britain, Scotland was designated as an officially (bovine) TB-free region in 2009. This paper investigates resultant possibilities for reducing surveillance by developing risk-based alternatives to current 4-year testing of eligible herds. A model of freedom of infection was used to develop strategies that specifically tested herds that are at risk of infection but would probably not be identified by slaughterhouse meat inspection. The performance of current testing is mimicked by testing all herds that slaughter fewer than 25% of their total stock per year and regularly import animals from high-incidence areas of England and Wales or from Ireland. This system offers a cost reduction by requiring 25% fewer herd and animal tests and 25% fewer false positives.

A stable "flat" form of two-dimensional crystals: could graphene, silicene, germanene be minigap semiconductors?

The discovery of a flat two-dimensional crystal known as graphene has contradicted Landau-Peierls-Mermin-Wagner arguments that there is no stable flat form of such crystals. Here, we show that the "flat" shape of graphene arises due to a microscopic buckling at the smallest possible interatomic scale. We show that the graphene, silicene, and other two-dimensional crystals are stable due to transverse short-range displacements of appropriate atoms. The distortions are small and form various patterns, which we describe in a framework of Ising model with competing interactions. We show that when temperature decreases, two transitions, disorder into order and order into disorder, arise. The ordered state has a form of stripes where carbon atoms are shifted regularly with respect to the plane. The flat graphene, silicene, or germanene planes look like a microscopic "washboard" with the wavelength of about couple of interatomic spacing of appropriate sublattices, which for graphene is about 1.8-3.6 Å. At lower temperatures, the ordered state transforms into a glass. Because of up-down asymmetry in buckled graphene, silicene and other two-dimensional crystals deposited on substrate, a minibandgap may arise. We derive a criterion for the minigap formation and show how it is related to the buckling and to the graphene-substrate interaction. Because of the bandgap, there may arise new phenomena and in particular a rectification of ac current induced by microwave or infrared radiation. We show that the amplitude of direct current arising at wave mixing of two harmonics of microwave electromagnetic radiation is huge. Moreover, we predict the existence of miniexcitons and a new type of fermionic minipolaritons whose behavior can be controlled by the microwave and terahertz radiation.

A genome scan localizes five non-MHC loci controlling collagen-induced arthritis in rats.

Identification of specific genetic loci that contribute to susceptibility to rheumatoid arthritis (RA) in humans has been hampered by several factors, including: i) multiple interacting genetic loci contributing to susceptibility; ii) complex interactions of environmental and genetic factors; iii) genetic heterogeneity; and iv) low penetrance. We have, therefore, mapped quantitative trait loci (QTLs) that control inflammatory arthritis susceptibility and/or severity in progeny of two inbred rat strains with significantly different susceptibilities to collagen-induced arthritis (CIA), an animal model for RA. Not surprisingly, we identified a major susceptibility factor, Cia1, on chromosome 20 in the vicinity of the rat major histocompatibility complex (MHC). However, by limiting the analysis to animals with arthritis-susceptible MHC genotypes and using genome-wide QTL analytic techniques, we also found four non-MHC QTLs-Cia2, 3, 4 and 5-on chromosomes 1, 4, 7 and 10, that contributed to disease severity. In addition, a QTL on chromosome 8 was suggestive for linkage. Characterization of the genes underlying these QTLs will facilitate the identification of key biochemical pathways regulating experimental autoimmune arthritis in rats and may provide insights into RA and other human autoimmune diseases. These genes may also represent novel targets for therapy.

Management of drooling in children: a survey of UK paediatricians' clinical practice.

BACKGROUND: Drooling is common in children with disordered oral-motor control. There is little evidence about the comparative effectiveness of different interventions used to reduce the impact of drooling. Anecdotal reports suggest clinicians' management of drooling varies widely. The aims of this survey were to establish which drooling interventions are currently used, how their effectiveness is monitored and how frequently adverse effects are reported. METHODS: 151 UK paediatricians completed a questionnaire about their management of drooling. RESULTS: Paediatricians saw one new child with problematic drooling and three follow-up children per month. The most common prescribing pattern was hyoscine first line (84.7%) followed by glycopyrronium bromide second line. The reported rate of adverse effects of medications was lower than expected (median 10% for hyoscine). Very few paediatricians used standardized methods of measuring the medication's effectiveness or adverse effects. CONCLUSION: Paediatricians regularly see small numbers of children with problematic drooling. Their clinical management of drooling varies; this is most likely because of a lack of evidence about the most effective approach. Comparative trials of interventions and the development of evidence-based clinical guidelines would improve the management of children's drooling.

Improving endovascular access to the target vessel for thrombus aspiration -Use of the wedge device to overcome anatomic hurdles.

BACKGROUND AND PURPOSE: Aspiration is a successful technique used in thrombectomy for acute stroke. It is contingent upon the appropriate position of the aspiration catheter, so that it is in contact with the thrombus. However, navigating the craniocervical vasculature is challenging is some patients. The wedge microcatheter (MicroVention®) is designed to reduce the gap between the microcatheter and the SofiaPlus 6F catheter for ease of advancement. The purpose of this study is to describe our initial experience with the wedge microcatheter. MATERIALS AND METHODS: A retrospective review of 38 consecutive patients in whom the wedge microcatheter was used during thrombectomy was performed to determine whether the wedge microcatheter was successful in delivering the Sofia catheter to the desired location. RESULTS: We have found this device to be successful in delivering the aspiration catheter to the correct position in 97% (N = 37) of cases. It was used predominantly to pass the origin of branching vessels and also to navigate the tortuous cavernous and petrous segments of the ICA. CONCLUSION: The wedge microcatheter is a successful tool in delivering the aspiration catheter to the desired vessel for revascularisation.

Early-life stress influences ion balance in developing zebrafish (Danio rerio).

As a key endocrine axis involved in responding to stress, the hypothalamic-pituitary-interrenal axis plays dual roles in mobilizing energy and maintaining ionic/osmotic balance in fishes. Although these roles have been examined independently in detail in adult fishes, less attention has been paid to the effects of an endogenous stress response during early life, particularly with respect to its potential effects on ionic/osmotic balance. The present study tested the hypothesis that exposure of zebrafish to stress during early development would alter ion balance later in life. Zebrafish at three developmental stages (4, 7, or 15 days post-fertilization, dpf) were subjected to an air-exposure stressor twice a day for 2 days, causing elevation of whole-body cortisol levels. Individuals stressed early in life exhibited decreased survival and growth, altered cortisol responses to a subsequent air-exposure stressor, and increased whole-body Na+ and Ca2+ concentrations. Changes in whole-body Ca2+ concentrations were accompanied by increased ionocyte abundance at 7 dpf and increased rates of Ca2+ uptake from the environment. Differences in whole-body ion concentrations at 15 and 35 dpf were not accompanied by altered ion uptake rates. Across all ages examined, air-exposure stress experienced at 7 dpf was particularly effective at eliciting phenotypic changes, suggesting a critical window at this age for a stress response to influence development. These findings demonstrate that early-life stress in zebrafish triggers developmental plasticity, with age-dependent effects on both the cortisol stress axis and ion balance.

Micropropagation, Genetic Fidelity and Phenolic Compound Production of Rheum rhabarbarum L.

An efficient micropropagation protocol for Rheum rhabarbarum L. was developed in this study. The in vitro rhubarb plants obtained in the multiplication stage (proliferation rate: 5.0 ± 0.5) were rooted in vitro (96% rooting percentage) and acclimatized ex vitro in floating perlite, with 90% acclimatization percentage. To assess the genetic fidelity between the mother plant and in vitro propagated plants, sequence-related amplified polymorphism (SRAP) markers were used. All banding profiles from the micropropagated plants were monomorphic and similar to those of the mother plant indicating 100% similarity. Regarding the polyphenolic profile, gallic, protocatechuic, p-hydroxybenzoic, vanillic, chlorogenic, caffeic, syringic, p-coumaric and ferulic acid were present in different amounts (2.3-2690.3 µg g-1 dry plant), according to the extracted matrix. Aglicons and glycosides of different classes of flavonoids were also identified. The rhizome extracts (both from in vitro and field grown plants) contained resveratrol, a stilbene compound with high antioxidant properties, ranging between 229.4 to 371.7 µg g-1 plant. Our results suggest that in vitro propagation of Rheum rhabarbarum L. represents a reliable alternative to obtain a large number of true-to-type planting material with high bioactive compound content of this valuable nutritional and medicinal species.

A Standardized Aspiration-First Approach for Thrombectomy to Increase Speed and Improve Recanalization Rates.

BACKGROUND AND PURPOSE: Direct aspiration is a recognized technique for revascularization in large-vessel ischemic strokes. There is ongoing debate regarding its efficacy compared with stent retrievers. Every delay in achieving revascularization and a decrease in reperfusion rates reduces the likelihood of patients achieving functional independence. We propose a standardized setup technique for aspiration-first for all anterior circulation thrombectomy procedures for increasing speed and recanalization rates. MATERIALS AND METHODS: We analyzed 127 consecutive patients treated by a standardized approach to thrombectomy with an intention to perform aspiration-first compared with 127 consecutive patients treated with a stent retriever-first approach. Key time metrics evaluated included groin to first angiogram, first angiogram to reperfusion, groin to first reperfusion, and length of the procedure. The degree of successful recanalization (TICI 2b-3) and the number of passes were compared between the 2 groups. RESULTS: In 127 patients who underwent the standardized technique, the median time from groin puncture to first reperfusion was 18 minutes compared with 26 minutes (P < .001). The duration of the procedure was shorter compared with the stent retriever group (26 minutes in the aspiration first group versus 47 minutes, P < .001) and required fewer passes (mean, 2.4 versus 3.1; P < .05). A higher proportion of patients had a TICI score of 2b-3 in the aspiration-first group compared with stent retriever group (96.1% versus 85.8%, P < .005). CONCLUSIONS: Our study highlights the increasing speed and recanalization rates achieved with fewer passes in a standardized approach to thrombectomy with an intention to attempt aspiration-first. Any attempt to reduce revascularization time and increase successful recanalization should be used.

Chronic kidney disease and postoperative mortality: a systematic review and meta-analysis.

Whether renal dysfunction is an important factor in postoperative risk assessment has been difficult to prove. In an attempt to provide more compelling evidence, we conducted a systematic review comparing the risk of death and cardiac events in patients with and without chronic kidney disease who underwent elective noncardiac surgery. From electronic databases, web search engines, and bibliographies, 31 cohort studies were selected, evaluating postoperative outcomes in patients with chronic kidney disease. These patients had higher risks of postoperative death and cardiovascular events compared to those with preserved renal function. The pooled incidence of postoperative death was significantly less in those with preserved renal function than in those patients with chronic kidney disease. Meta-regression showed a graded relationship between disease severity and postoperative death. In adjusted analysis, chronic kidney disease had a similar strength of association with postoperative death as diabetes, stroke, and coronary disease. Our review identifies chronic kidney disease as an independent risk factor for postoperative death and cardiovascular events after elective, noncardiac surgery.

Neighborhood poverty and kidney transplantation among US Asians and Pacific Islanders with end-stage renal disease.

The degree to which low transplant rates among Asians and Pacific Islanders in the United States are confounded by poverty and reduced access to care is unknown. We examined the relationship between neighborhood poverty and kidney transplant rates among 22 152 patients initiating dialysis during 1995-2003 within 1800 ZIP codes in California, Hawaii and the US-Pacific Islands. Asians and whites on dialysis were distributed across the spectrum of poverty, while Pacific Islanders were clustered in the poorest areas. Overall, worsening neighborhood poverty was associated with lower relative rates of transplant (adjusted HR [95% CI] for areas with > or =20% vs. <5% residents living in poverty, 0.41 [0.32-0.53], p < 0.001). At every level of poverty, Asians and Pacific Islanders experienced lower transplant rates compared with whites. The degree of disparity increased with worsening neighborhood poverty (adjusted HR [95% CI] for Asians-Pacific Islanders vs. whites, 0.64 [0.51-0.80], p < 0.001 for areas with <5% and 0.30 [0.21-0.44], p < 0.001 for areas with > or =20% residents living in poverty; race-poverty level interaction, p = 0.039). High levels of neighborhood poverty are associated with lower transplant rates among Asians and Pacific Islanders compared with whites. Our findings call for studies to identify cultural and local barriers to transplant among Asians and Pacific Islanders, particularly those residing in resource-poor neighborhoods.

Characterisation of an optical clock recovery method based on a mode-locked laser diode using spectrographic pulse measurement.

As channels rates in optical networks are expected to exceed 100 Gb/s in the near future, new optical techniques for clock recovery will have to be developed for optical regeneration. This paper describes an optical clock recovery method based on a mode-locked laser diode. Experimental results show that a 42 GHz high quality optical clock can be retrieved from a 170 Gb/s OTDM data signal. Chirp transfer between the incident signal and the recovered clock signal is investigated using the SHG-FROG method. Results demonstrate that this clock recovery technique is invariant to input dispersion varying between +/-75 ps/nm, making it ideal for use in 3R regenerators.