Localisation Of The Subthalamic Nucleus In Parkinson’s Disease with Neural Beta and Gamma Activity of Local Field Potentials

Introduction: To refine the MRI-based target during DBS surgery, microelectrode recordings (MER) are often performed to detect target-specific single unit activity. This requires additional recording time and increases the risk for haemorrhage. In the future it may therefore be relevant to be able to determine the implantable lead's position based on local field potential (LFP) recordings from the lead itself which reflect activity of a larger neural population. This study aims to evaluate the nature of oscillatory activity in the subthalamic nucleus (STN) by means of intraoperative LFP-recordings, its relationship with microelectrode recordings and its potential use to locate the STN and its sensorimotor sub-area in patients with Parkinson’s disease during deep brain stimulation (DBS) surgery.Methods: 25 patients with Parkinson’s disease are included in this study. MER and LFPs are recorded every 0.5 mm from multiple microelectrodes during DBS surgery in 48 STNs. A novel optimization approach to map the measurement points on an atlas STN based on the MER properties is used to enable a detailed spatial representation of these points. Power and coherence in different LFP frequencies at all points are assessed in reference to the point's location inside or outside the STN and its sensorimotor sub-area.Results: Coherence between LFPs and the envelope of spiking activity significantly increases when entering the STN. There is also a pronounced increase in the LFP power in the gamma band, which persists throughout the entire STN in 100% of the cases. In 70% of the cases LFPs have a significantly higher power in the high beta frequency band in the sensorimotor STN, defined by the mapping algorithm, compared to the non-sensorimotor STN.Conclusions: LFP gamma oscillations provide a useful tool for locating the STN intraoperatively and LFP beta oscillations can become useful to discriminate the sensorimotor area within the STN

Long-term experience with intraoperative microrecording during DBS neurosurgery in STN and GPi

Intraoperative microelectrode recording (MER) for targeting during deep brain stimulation (DBS) procedures has been evaluated over a period of 4 years, in 57 consecutive patients with Parkinson's disease, who received DBS in the subthalamic nucleus (STN-DBS), and 28 consecutive patients with either dystonia (23) or Parkinson's disease (five), in whom the internal segment of the globus pallidus (GPi-DBS) was targeted. The procedure for DBS was a one-stage bilateral stereotactic approach using a combined electrode for both MER and macrostimulation. Up to five micro/macro-electrodes were used in an array with a central, lateral, medial, anterior, and posterior position. Final target location was based on intraoperative test stimulation. For the STN, the central trajectory was chosen for implantation in 50% of the cases and for the globus pallidus internus (GPi) in 57% of the cases. Furthermore, in 64% of the cases, the channel selected for the permanent electrode corresponded with the trajectory having the longest segment of STN MER activity. For the GPi, this was the case in 61%. The mean and standard deviation of the deepest contact point with respect to the magnetic resonance imaging (MRI)-based target for the STN was 2.1 +/- 1.5 mm and for the GPi was -0.5 +/- 1.2 mm. MER facilitates the selection of the final electrode location in STN-DBS and GPi-DBS, and based on the observed MER activity, a pre-selection could be made as to which channel would be the best candidate for macro-test stimulation and at which depth should be stimulated. The choice of the final location is based on intraoperative test stimulation, and it is demonstrated that regularly it is not the central channel that is chosen for implantation. On average, the target as defined by MER activity intensity was in accordance with the MRI-based targets both for the STN and GPi. However, the position of the best MER activity did not necessarily correlate with the locus that produced the most beneficial clinical response on macroelectrode testing intraoperativel

Epidemiological and Biological Evidence for a Compensatory Effect of Connection Domain Mutation N348I on M184V in HIV-1 Reverse Transcriptase

Background. The connection domain mutation N348I confers resistance to zidovudine (AZT) and is associated with the lamivudine (3TC) mutation M184V. We explored the biochemical and virological influence of N348I in the context of M184V. Methods. Genotypic resistance data for patients receiving monotherapy or dual therapy with AZT, lamivudine (3TC), or AZT/3TC were analyzed. Rates of N348I emergence were compared between treatment groups. Mutant reverse transcriptases (RTs) containing M184V and/or N348I were generated to study enzymatic and virological properties. Results. We included 50 AZT-treated, 11 3TC-treated, and 10 AZT/3TC-treated patients. N348I was observed in 3 (6%), 0, and 4 (40%) of these patients, respectively. The rate of N348I emergence was increased by 5-fold in the AZT/3TC group (11.7 instances [95% confidence interval {CI}, 3.2-30.1 instances] per 100 person-years of receipt of AZT), compared with the rate noted for the AZT group (2.3 instances [95% CI, 0.4-6.8 instances] per 100 person-years of receipt of AZT; P = .04). Biochemical data show that N348I can partially compensate for the diminution in processive DNA synthesis and the reduction in AZT excision associated with M184V. Furthermore, virological analyses demonstrate that N348I confers low-level resistance to AZT and partly restores the reduced RT activity of the M184V variant. Conclusion. In vivo selection of N348I is driven by AZT and is further facilitated when 3TC is coadministered. Compensatory interactions between N348I and M184V help to explain these finding

HIV-1 Reverse Transcriptase Connection Domain Mutations: Dynamics of Emergence and Implications for Success of Combination Antiretroviral Therapy

Background. Factors promoting the emergence of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) connection domain mutations and their effect on antiretroviral therapy (ART) are still largely undetermined.We investigated this matter by analyzing genotypic resistance tests covering 400 amino acid positions in the RT of HIV-1 subtype B viruses and corresponding treatment histories and laboratory measurements. Methods. The emergence of connection domain mutations was studied in 334 patients receiving monotherapy or dual therapy with thymidine analogues at the time of the genotypic resistance test. Response to subsequent combination ART (cART) was analyzed using Cox regression for 291 patients receiving unboosted protease inhibitors. Response was defined by ever reaching an HIV RNA level <50 copies/mL during the first cART. Results. The connection domain mutations N348I, R356K, R358K, A360V, and A371V were more frequently observed in ART-exposed than ART-naive patients, of which only N348I and A360V were nonpolymorphic (with a prevalence of <1.5% in untreated patients). N348I correlated with M184V and predominantly occurred in patients receiving lamivudine and zidovudine concomitantly. A360V was not associated with specific drug combinations and was found to emerge later than M184V or thymidine analogue mutations. Nonpolymorphic connection domain mutations were rarely detected in the absence of established drug resistance mutations in ART-exposed individuals (prevalence, <1%). None of the 5 connection domain mutations associated with treatment showed a statistically significant effect on response to cART. Conclusions. Despite their frequent emergence, connection domain mutations did not show large detrimental effects on response to cART. Currently, routine implementation of connection domain sequencing seems unnecessary for developed health care setting

Low-frequency drug-resistant HIV-1 and risk of virological failure to first-line NNRTI-based ART: a multicohort European case-control study using centralized ultrasensitive 454 pyrosequencing

Objectives It is still debated if pre-existing minority drug-resistant HIV-1 variants (MVs) affect the virological outcomes of first-line NNRTI-containing ART. Methods This Europe-wide case-control study included ART-naive subjects infected with drug-susceptible HIV-1 as revealed by population sequencing, who achieved virological suppression on first-line ART including one NNRTI. Cases experienced virological failure and controls were subjects from the same cohort whose viraemia remained suppressed at a matched time since initiation of ART. Blinded, centralized 454 pyrosequencing with parallel bioinformatic analysis in two laboratories was used to identify MVs in the 1%-25% frequency range. ORs of virological failure according to MV detection were estimated by logistic regression. Results Two hundred and sixty samples (76 cases and 184 controls), mostly subtype B (73.5%), were used for the analysis. Identical MVs were detected in the two laboratories. 31.6% of cases and 16.8% of controls harboured pre-existing MVs. Detection of at least one MV versus no MVs was associated with an increased risk of virological failure (OR = 2.75, 95% CI = 1.35-5.60, P = 0.005); similar associations were observed for at least one MV versus no NRTI MVs (OR = 2.27, 95% CI = 0.76-6.77, P = 0.140) and at least one MV versus no NNRTI MVs (OR = 2.41, 95% CI = 1.12-5.18, P = 0.024). A dose-effect relationship between virological failure and mutational load was found. Conclusions Pre-existing MVs more than double the risk of virological failure to first-line NNRTI-based AR

Screening for SARS-CoV-2 infection in asymptomatic individuals using the Panbio COVID-19 antigen rapid test (Abbott) compared with RT-PCR: A prospective cohort study

Background Antigen-based point-of-care tests for identification of SARS-CoV-2 may markedly enhance effectiveness of population-based controlling strategies. Previous studies have demonstrated >70% sensitivity and high specificity compared with reverse transcriptase real-time PCR (RT-PCR) in symptomatic individuals, but test performance for asymptomatic individuals is unknown. Methods Test performance of the Panbio COVID-19 Ag Rapid Test (Abbott) was compared with RT-PCR in a longitudinal cohort study of asymptomatic football players and staff members of professional football clubs. Based on timing of symptoms and prior and subsequent test results, positive RT-PCR tests were categorised as presymptomatic, early or late infection, or persistent RNA shedding. Findings 2425 tests were performed in 824 individuals, of which 52 (6.3%) were SARS-CoV-2 positive based on RT-PCR. There were 2406 paired sets from asymptomatic subjects for analysis. Sixteen Panbio tests were inconclusive, for which sensitivity analyses were performed (considering results as either positive or negative or being excluded). Sensitivity of Panbio for screening of asymptomatic individuals ranged from 80.0% (61.4-92.3) to 86.67% (69.2-96.2) and specificity from 99.53% (95% CI 99.2 to 99.8) to 100% (95% CI 99.8 to 100). Sensitivity of Panbio to detect subjects with presymptomatic/early infection (n=42) ranged from 81.82% (95% CI 67.3 to 91.8) to 90.91% (95% CI 78.3 to 97.5) with specificity always above 99%. Interpretation The Panbio COVID-19 Ag rapid test identifies 81%-90% of presymptomatic and early asymptomatic SARS-CoV-2 infections with high specificity. This test may therefore be adopted in testing strategies such as targeted screening of specific populations where prevalence is low

Laboratory-based surveillance in the molecular era: The typened model, a joint data-sharing platform for clinical and public health laboratories

Laboratory-based surveillance, one of the pillars of monitoring infectious disease trends, relies on data produced in clinical and/or public health laboratories. Currently, diagnostic laboratories worldwide submit strains or samples to a relatively small number of reference laboratories for characterisation and typing. However, with the introduction of molecular diagnostic methods and sequencing in most of the larger diagnostic and university hospital centres in high-income countries, the distinction between diagnostic and reference/public health laboratory functions has become less clear-cut. Given these developments, new ways of networking and data sharing are needed. Assuming that clinical and public health laboratories may be able to use the same data for their own purposes when sequence-based testing and typing are used, we explored ways to develop a collaborative approach and a jointly owned database (TYPENED) in the Netherlands. The rationale was that sequence data - whether produced to support clinical care or for surveillance -can be aggregated to meet both needs. Here we describe the development of the TYPENED approach and supporting infrastructure, and the implementation of a pilot laboratory network sharing enterovirus sequences and metadata