Engineering a Point-of-Care Paper-Microfluidic Electrochemical Device Applied to the Multiplexed Quantitative Detection of Biomarkers in Sputum.

Health initiatives worldwide demand affordable point-of-care devices to aid in the reduction of morbidity and mortality rates of high-incidence infectious and noncommunicable diseases. However, the production of robust and reliable easy-to-use diagnostic platforms showing the ability to quantitatively measure several biomarkers in physiological fluids and that could in turn be decentralized to reach any relevant environment remains a challenge. Here, we show the particular combination of paper-microfluidic technology, electrochemical transduction, and magnetic nanoparticle-based immunoassay approaches to produce a unique, compact, and easily deployable multiplex device to simultaneously measure interleukin-8, tumor necrosis factor-α, and myeloperoxidase biomarkers in sputum, developed with the aim of facilitating the timely detection of acute exacerbations of chronic obstructive pulmonary disease. The device incorporates an on-chip electrochemical cell array and a multichannel paper component, engineered to be easily aligned into a polymeric cartridge and exchanged if necessary. Calibration curves at clinically relevant biomarker concentration ranges are produced in buffer and artificial sputum. The analysis of sputum samples of healthy individuals and acutely exacerbated patients produces statistically significant biomarker concentration differences between the two studied groups. The device can be mass-produced at a low cost, being an easily adaptable platform for measuring other disease-related target biomarkers.

Current territorial organization for access to revascularization therapies for acute ischemic stroke in the Veneto region (Italy) from 2017 to 2021.

INTRODUCTION: To evaluate the access to treatments with intravenous thrombolysis (IVT) and/or mechanical thrombectomy (MT) in acute ischemic stroke patients admitted to stroke units (SUs) of Veneto region (Italy) according to current "hub-and-spoke" model from 2017 to 2021. PATIENTS AND METHODS: We retrospectively analyzed data on treatments with IVT and/or MT for stroke patients admitted to the 23 SUs (6 Hubs and 17 Spokes) of the 6 macro-areas including 9 local sanitary units (LSUs) and 2 hospitals. RESULTS: We reported 6093 treatments with IVT alone, 1114 with IVT plus MT, and 921 with MT alone. Number of stroke unit (SU) beds/100,000 inhabitants ranges from 2.3 to 2.8, and no difference was found among different macro-areas. Number of treatments/100,000 inhabitants/year ranges from 19 to 34 for IVT alone, from 2 to 7 for IVT plus MT, and from 2 to 5 for MT alone. Number of IVT alone/SU bed/year ranges from 9 to 21 in the Hub and from 6 to 12 in the Spokes. Rate of IVT plus MT in patients directly arrived in the same LSU's Hub ranges from 50 to 81%, likewise the one of MT alone ranges from 49 to 84%. CONCLUSIONS: Treatment target rates of IVT and MT set by Action Plan for Stroke in Europe 2018-2030 has been globally exceeded in the Veneto region. However, the target rate of MT and access revascularization treatments is heterogeneous among different macro-areas. Further efforts should be made to homogenize the current territorial organization.

Detection of SARS-CoV-2 Virus by Triplex Enhanced Nucleic Acid Detection Assay (TENADA).

SARS-CoV-2, a positive-strand RNA virus has caused devastating effects. The standard method for COVID diagnosis is based on polymerase chain reaction (PCR). The method needs expensive reagents and equipment and well-trained personnel and takes a few hours to be completed. The search for faster solutions has led to the development of immunological assays based on antibodies that recognize the viral proteins that are faster and do not require any special equipment. Here, we explore an innovative analytical approach based on the sandwich oligonucleotide hybridization which can be adapted to several biosensing devices including thermal lateral flow and electrochemical devices, as well as fluorescent microarrays. Polypurine reverse-Hoogsteen hairpins (PPRHs) oligonucleotides that form high-affinity triplexes with the polypyrimidine target sequences are used for the efficient capture of the viral genome. Then, a second labeled oligonucleotide is used to detect the formation of a trimolecular complex in a similar way to antigen tests. The reached limit of detection is around 0.01 nM (a few femtomoles) without the use of any amplification steps. The triplex enhanced nucleic acid detection assay (TENADA) can be readily adapted for the detection of any pathogen requiring only the knowledge of the pathogen genome sequence.

Compact Microfluidic Platform with LED Light-Actuated Valves for Enzyme-Linked Immunosorbent Assay Automation.

Lab-on-a-chip devices incorporating valves and pumps can perform complex assays involving multiple reagents. However, the instruments used to drive these chips are complex and bulky. In this article, a new wax valve design that uses light from a light emitting diode (LED) for both opening and closing is reported. The valves and a pumping chamber are integrated in lab-on-a-foil chips that can be fabricated at low cost using rapid prototyping techniques. A chip for the implementation of enzyme-linked immunosorbent assays (ELISA) is designed. A porous nitrocellulose material is used for the immobilization of capture antibodies in the microchannel. A compact generic instrument with an array of 64 LEDs, a linear actuator to drive the pumping chamber, and absorbance detection for a colorimetric readout of the assay is also presented. Characterization of all the components and functionalities of the platform and the designed chip demonstrate their potential for assay automation.

Experimental image dataset for validation of the noise-induced bias that affects Digital Image Correlation.

The present article shares with the scientific community several image sets used for experimentally validating the noise-induced bias on different Digital Image Correlation (DIC) formulations, as reported in Baldi et al. [1]. These sets are provided with a description of the experimental setup used for image acquisition. The basic idea is to acquire a series of images obtained by rigidly translating the target, where incremental displacement is of the order of a small fraction of a pixel. This condition requires a high-precision control of the target position through the tests. Moreover, the noise content of each image set is modulated using a statistical approach that uncouples the intensity field from the standard deviation. Lastly, the images are acquired with different exposure conditions to analyze the gray tone gradient effect on noise-induced bias.

Stroke management during the coronavirus disease 2019 (COVID-19) pandemic: experience from three regions of the north east of Italy (Veneto, Friuli-Venezia-Giulia, Trentino-Alto-Adige).

BACKGROUND: Efficiency of care chain response and hospital reactivity were and are challenged for stroke acute care management during the pandemic period of coronavirus disease 2019 (COVID-19) in North-Eastern Italy (Veneto, Friuli-Venezia-Giulia, Trentino-Alto-Adige), counting 7,193,880 inhabitants (ISTAT), with consequences in acute treatment for patients with ischemic stroke. METHODS: We conducted a retrospective data collection of patients admitted to stroke units eventually treated with thrombolysis and thrombectomy, ranging from January to May 2020 from the beginning to the end of the main first pandemic period of COVID-19 in Italy. The primary endpoint was the number of patients arriving to these stroke units, and secondary endpoints were the number of thrombolysis and/or thrombectomy. Chi-square analysis was used on all patients; furthermore, patients were divided into two cohorts (pre-lockdown and lockdown periods) and the Kruskal-Wallis test was used to test differences on admission and reperfusive therapies. RESULTS: In total, 2536 patients were included in 22 centers. There was a significant decrease of admissions in April compared to January. Furthermore, we observed a significant decrease of thrombectomy during the lockdown period, while thrombolysis rate was unaffected in the same interval across all centers. CONCLUSIONS: Our study confirmed a decrease in admission rate of stroke patients in a large area of northern Italy during the lockdown period, especially during the first dramatic phase. Overall, there was no decrease in thrombolysis rate, confirming an effect of emergency care system for stroke patients. Instead, the significant decrease in thrombectomy rate during lockdown addresses some considerations of local and regional stroke networks during COVID-19 pandemic evolution.

Acute revascularization treatments for ischemic stroke in the Stroke Units of Triveneto, northeast Italy: time to treatment and functional outcomes.

It is not known whether the current territorial organization for acute revascularization treatments in ischemic stroke patients guarantees similar time to treatment and functional outcomes among different levels of institutional stroke care. We aimed to assess the impact of time to treatment on functional outcomes in ischemic stroke patients who received intravenous thrombolysis (IVT) alone, bridging (IVT plus thrombectomy), or primary thrombectomy in level 1 and level 2 Stroke Units (SUs) in Triveneto, a geographical macroarea in Northeast of Italy. We conducted an analysis of data prospectively collected from 512 consecutive ischemic stroke patients who received IVT and/or mechanical thrombectomy in 25 SUs from September 17th to December 9th 2018. The favorable outcome measures were mRS score 0-1 and 0-2 at 3 months. The unfavorable outcome measures were mRS score 3-5 and death at 3 months. We estimated separately the possible association of each variable for time to treatment (onset-to-door, door-to-needle, onset-to-needle, door-to-groin puncture, needle-to-groin puncture, and onset-to-groin puncture) with 3-month outcome measures by calculating the odds ratios (ORs) with two-sided 95% confidence intervals (CI) after adjustment for pre-defined variables and variables with a probability value ≤ 0.10 in the univariate analysis for each outcome measure. Distribution of acute revascularization treatments was different between level 1 and level 2 SUs (p < 0.001). Among 182 patients admitted to level 1 SUs (n = 16), treatments were IVT alone in 164 (90.1%), bridging in 12 (6.6%), and primary thrombectomy in 6 (3.3%) patients. Among 330 patients admitted to level 2 SUs (n = 9), treatments were IVT alone in 219 (66.4%), bridging in 74 (22.4%), and primary thrombectomy in 37 (11.2%) patients. Rates of excellent outcome (51.4% vs 45.9%), favorable outcome (60.1% vs 58.7%), unfavorable outcome (33.3% vs 33.8%), and death (9.8% vs 11.3%) at 3 months were similar between level 1 and 2 SUs. No significant association was found between time to IVT alone (onset-to-door, door-to-needle, and onset-to-needle) and functional outcomes. After adjustment, door-to-needle time ≤ 60 min (OR 4.005, 95% CI 1.232-13.016), shorter door-to-groin time (OR 0.991, 95% CI 0.983-0.999), shorter needle-to-groin time (OR 0.986, 95% CI 0.975-0.997), and shorter onset-to-groin time (OR 0.994, 95% CI 0.988-1.000) were associated with mRS 0-1. Shorter door-to-groin time (OR 0.991, 95% CI 0.984-0.998), door-to-groin time ≤ 90 min (OR 12.146, 95% CI 2.193-67.280), shorter needle-to-groin time (OR 0.983, 95% CI 0.972-0.995), and shorter onset-to-groin time (OR 0.993, 95% CI 0.987-0.999) were associated with mRS 0-2. Longer door-to-groin time (OR 1.007, 95% CI 1.001-1.014) and longer needle-to-groin time (OR 1.019, 95% CI 1.005-1.034) were associated with mRS 3-5, while door-to-groin time ≤ 90 min (OR 0.229, 95% CI 0.065-0.808) was inversely associated with mRS 3-5. Longer onset-to-needle time (OR 1.025, 95% CI 1.002-1.048) was associated with death. Times to treatment influenced the 3-month outcomes in patients treated with thrombectomy (bridging or primary). A revision of the current territorial organization for acute stroke treatments in Triveneto is needed to reduce transfer time and to increase the proportion of patients transferred from a level 1 SU to a level 2 SU to perform thrombectomy.

Electrochemical Paper-Based Biosensor Devices for Rapid Detection of Biomarkers.

In healthcare, new diagnostic tools that help in the diagnosis, prognosis, and monitoring of diseases rapidly and accurately are in high demand. For in-situ measurement of disease or infection biomarkers, point-of-care devices provide a dramatic speed advantage over conventional techniques, thus aiding clinicians in decision-making. During the last decade, paper-based analytical devices, combining paper substrates and electrochemical detection components, have emerged as important point-of-need diagnostic tools. This review highlights significant works on this topic over the last five years, from 2015 to 2019. The most relevant articles published in 2018 and 2019 are examined in detail, focusing on device fabrication techniques and materials applied to the production of paper fluidic and electrochemical cell architectures as well as on the final device assembly. Two main approaches were identified, that are, on one hand, those ones where the fabrication of the electrochemical cell is done on the paper substrate, where the fluidic structures are also defined, and, on the other hand, the fabrication of those ones where the electrochemical cell and liquid-driving paper component are defined on different substrates and then heterogeneously assembled. The main limitations of the current technologies are outlined and an outlook on the current technology status and future prospects is given.

Automated Determination of As(III) in Waters with an Electrochemical Sensor Integrated into a Modular Microfluidic System.

The presence of high levels of arsenic in waters poses a threat to the human health in many countries all over the world. Effective surveillance programs of water quality require the implementation of in-field tests to assess early the presence of this metal ion and other contaminants. To date, there exist few market-available analytical approaches that suffer from important limitations related to cost, in addition to complex reactions, very long analysis times, and/or high limits of detection. This work describes a robust electrochemical sensor integrated into a modular microfluidic system that shows a clear potential to be deployed for the on-site monitoring of inorganic As(III) species. Flexible and transparent microfluidic modules are fabricated by rapid prototyping techniques and include different microfluidic components among them, flow cells where electrochemical sensors can be easily and reversibly inserted. The electrochemical sensor comprises a gold nanoparticle (AuNP)-modified gold thin-film electrode that is readily applied to the sensitive detection of As(III) by anodic stripping linear sweep voltammetry. The microfluidic system enables the automatic sensor calibration, sample uptake, and preconditioning as well as As(III) detection. The system response to As(III) is linear in a concentration range of 1-150 µg L-1, with a detection limit of 0.42 µg L-1, which is well below the threshold value of 10 µg L-1 set by the World Health Organization. Analysis of tap water and two water samples from two Argentinean aquifers, spiked with different As(III) concentrations, demonstrates the excellent performance of the system.

Serum Interleukin-10 Levels Correlate with Cerebrospinal Fluid Amyloid Beta Deposition in Alzheimer Disease Patients.

BACKGROUND AND OBJECTIVE: In Alzheimer disease (AD) inflammation becomes evident throughout the course of the disease. However, the association between inflammation, cognitive impairment, and cerebrospinal biomarkers (Aß42, t-tau, p-tau181, and Aß42/p-tau181 ratio) is poorly understood. METHODS: A large panel of inflammatory cytokines (interleukin [IL]-1ß, IL-1ra, IL-2, IL-4, IL-6, IL-10, IL-17, interferon-γ, tumor necrosis factor-α, and vascular endothelial growth factor) was analyzed using a multiplex immunoassay in 27 patients with a diagnosis of AD dementia and in 18 control subjects. In a subgroup with available cerebrospinal fluid (CSF) samples, cytokines in serum were correlated with the levels of neurodegenerative CSF biomarkers (Aß42, t-tau, p-tau181, and Aß42/p-tau181 ratio). RESULTS: Compared to control subjects, AD patients showed a significant upregulation of IL-10, IL-1ß, and IL-17 serum levels. Several cytokines appeared intercorrelated, and IL-10 in particular presented a significant inverse correlation with CFS levels of Aß42 and the Aß42/p-tau ratio. CONCLUSION: Our findings indicate that serum levels of IL-10 may represent a possible peripheral expression of amyloid beta deposition in AD patients.

Prestroke CHA2DS2-VASc Score and Severity of Acute Stroke in Patients with Atrial Fibrillation: Findings from RAF Study.

BACKGROUND AND PURPOSE: The aim of this study was to investigate for a possible association between both prestroke CHA2DS2-VASc score and the severity of stroke at presentation, as well as disability and mortality at 90 days, in patients with acute stroke and atrial fibrillation (AF). METHODS: This prospective study enrolled consecutive patients with acute ischemic stroke, AF, and assessment of prestroke CHA2DS2-VASc score. Severity of stroke was assessed on admission using the National Institutes of Health Stroke Scale (NIHSS) score (severe stroke: NIHSS ≥10). Disability and mortality at 90 days were assessed by the modified Rankin Scale (mRS <3 or ≥3). Multiple logistic regression was used to correlate prestroke CHA2DS2-VASc and severity of stroke, as well as disability and mortality at 90 days. RESULTS: Of the 1020 patients included in the analysis, 606 patients had an admission NIHSS score lower and 414 patients higher than 10. At 90 days, 510 patients had mRS ≥3. A linear correlation was found between the prestroke CHA2DS2-VASc score and severity of stroke (P = .001). On multivariate analysis, CHA2DS2-VASc score correlated with severity of stroke (P = .041) and adverse functional outcome (mRS ≥3) (P = .001). A logistic regression with the receiver operating characteristic graph procedure (C-statistics) evidenced an area under the curve of .60 (P = .0001) for severe stroke. Furthermore, a correlation was found between prestroke CHA2DS2-VASc score and lesion size. CONCLUSIONS: In patients with AF, in addition to the risk of stroke, a high CHA2DS2-VASc score was independently associated with both stroke severity at onset and disability and mortality at 90 days.

Sex-related differences in risk factors, type of treatment received and outcomes in patients with atrial fibrillation and acute stroke: Results from the RAF-study (Early Recurrence and Cerebral Bleeding in Patients with Acute Ischemic Stroke and Atrial Fibrillation).

INTRODUCTION: Atrial fibrillation is an independent risk factor of thromboembolism. Women with atrial fibrillation are at a higher overall risk for stroke compared to men with atrial fibrillation. The aim of this study was to evaluate for sex differences in patients with acute stroke and atrial fibrillation, regarding risk factors, treatments received and outcomes. METHODS: Data were analyzed from the "Recurrence and Cerebral Bleeding in Patients with Acute Ischemic Stroke and Atrial Fibrillation" (RAF-study), a prospective, multicenter, international study including only patients with acute stroke and atrial fibrillation. Patients were followed up for 90 days. Disability was measured by the modified Rankin Scale (0-2 favorable outcome, 3-6 unfavorable outcome). RESULTS: Of the 1029 patients enrolled, 561 were women (54.5%) (p < 0.001) and younger (p < 0.001) compared to men. In patients with known atrial fibrillation, women were less likely to receive oral anticoagulants before index stroke (p = 0.026) and were less likely to receive anticoagulants after stroke (71.3% versus 78.4%, p = 0.01). There was no observed sex difference regarding the time of starting anticoagulant therapy between the two groups (6.4 ± 11.7 days for men versus 6.5 ± 12.4 days for women, p = 0.902). Men presented with more severe strokes at onset (mean NIHSS 9.2 ± 6.9 versus 8.1 ± 7.5, p < 0.001). Within 90 days, 46 (8.2%) recurrent ischemic events (stroke/TIA/systemic embolism) and 19 (3.4%) symptomatic cerebral bleedings were found in women compared to 30 (6.4%) and 18 (3.8%) in men (p = 0.28 and p = 0.74). At 90 days, 57.7% of women were disabled or deceased, compared to 41.1% of the men (p < 0.001). Multivariate analysis did not confirm this significance. CONCLUSIONS: Women with atrial fibrillation were less likely to receive oral anticoagulants prior to and after stroke compared to men with atrial fibrillation, and when stroke occurred, regardless of the fact that in our study women were younger and with less severe stroke, outcomes did not differ between the sexes.

Multiple actuation microvalves in wax microfluidics.

Microvalves are an essential component of microfluidic devices. In this work, a low-consumption (<35 mJ), fast-response (<0.3 s), small footprint (<0.5 mm2) wax microvalve capable of multiple actuation is described. This phase-change microvalve is electrically controlled, simple to operate and can be easily fabricated as a fully integrated element of wax microfluidic devices through a special decal-transfer microlithographic process. The valve is inherently latched and leak-proof to at least 100 kPa. A minimum pressure of 3 kPa is required for valve opening. Maximum pressures for a successful closing in air and liquid are 90 and 40 kPa, respectively. The wax valve exhibits reversible open-close behaviour without failure for up to 10 actuation cycles in air (60 kPa) and 5 in water (30 kPa). To the best of our knowledge, this microvalve has the lowest energy consumption (two orders of magnitude lower) reported so far for a plug-type phase-change valve. Furthermore, its size, actuation mechanism and fabrication technology make it suitable for large-scale integration in microfluidic devices. Detailed characteristics in fabrication and actuation of the wax microfluidic valve as well as a test example of its performance for liquid dispensing are reported.

Prognostic value of trans-thoracic echocardiography in patients with acute stroke and atrial fibrillation: findings from the RAF study.

Anticoagulant therapy is recommended for the secondary prevention of stroke in patients with atrial fibrillation (AF). T he identification of patients at high risk for early recurrence, which are potential candidates to prompt anticoagulation, is crucial to justify the risk of bleeding associated with early anticoagulant treatment. The aim of this study was to evaluate in patients with acute ischemic stroke and AF the association between findings at trans-thoracic echocardiography (TTE) and 90 days recurrence. In consecutive patients with acute ischemic stroke and AF, TTE was performed within 7 days from hospital admission. Study outcomes were recurrent ischemic cerebrovascular events (stroke or TIA) and systemic embolism. 854 patients (mean age 76.3 ± 9.5 years) underwent a TTE evaluation; 63 patients (7.4%) had at least a study outcome event. Left atrial thrombosis was present in 11 patients (1.3%) among whom 1 had recurrent ischemic event. Left atrial enlargement was present in 548 patients (64.2%) among whom 51 (9.3%) had recurrent ischemic events. The recurrence rate in the 197 patients with severe left atrial enlargement was 11.7%. On multivariate analysis, the presence of atrial enlargement (OR 2.13; 95% CI 1.06-4.29, p = 0.033) and CHA2DS2-VASc score (OR 1.22; 95% CI 1.04-1.45, p = 0.018, for each point increase) were correlated with ischemic recurrences. In patients with AF-associated acute stroke, left atrial enlargement is an independent marker of recurrent stroke and systemic embolism. The risk of recurrence is accounted for by severe atrial enlargement. TTE-detected left atrial thrombosis is relatively uncommon.

Early Recurrence and Cerebral Bleeding in Patients With Acute Ischemic Stroke and Atrial Fibrillation: Effect of Anticoagulation and Its Timing: The RAF Study.

BACKGROUND AND PURPOSE: The best time for administering anticoagulation therapy in acute cardioembolic stroke remains unclear. This prospective cohort study of patients with acute stroke and atrial fibrillation, evaluated (1) the risk of recurrent ischemic event and severe bleeding; (2) the risk factors for recurrence and bleeding; and (3) the risks of recurrence and bleeding associated with anticoagulant therapy and its starting time after the acute stroke. METHODS: The primary outcome of this multicenter study was the composite of stroke, transient ischemic attack, symptomatic systemic embolism, symptomatic cerebral bleeding and major extracranial bleeding within 90 days from acute stroke. RESULTS: Of the 1029 patients enrolled, 123 had 128 events (12.6%): 77 (7.6%) ischemic stroke or transient ischemic attack or systemic embolism, 37 (3.6%) symptomatic cerebral bleeding, and 14 (1.4%) major extracranial bleeding. At 90 days, 50% of the patients were either deceased or disabled (modified Rankin score ≥3), and 10.9% were deceased. High CHA2DS2-VASc score, high National Institutes of Health Stroke Scale, large ischemic lesion and type of anticoagulant were predictive factors for primary study outcome. At adjusted Cox regression analysis, initiating anticoagulants 4 to 14 days from stroke onset was associated with a significant reduction in primary study outcome, compared with initiating treatment before 4 or after 14 days: hazard ratio 0.53 (95% confidence interval 0.30-0.93). About 7% of the patients treated with oral anticoagulants alone had an outcome event compared with 16.8% and 12.3% of the patients treated with low molecular weight heparins alone or followed by oral anticoagulants, respectively (P=0.003). CONCLUSIONS: Acute stroke in atrial fibrillation patients is associated with high rates of ischemic recurrence and major bleeding at 90 days. This study has observed that high CHA2DS2-VASc score, high National Institutes of Health Stroke Scale, large ischemic lesions, and type of anticoagulant administered each independently led to a greater risk of recurrence and bleedings. Also, data showed that the best time for initiating anticoagulation treatment for secondary stroke prevention is 4 to 14 days from stroke onset. Moreover, patients treated with oral anticoagulants alone had better outcomes compared with patients treated with low molecular weight heparins alone or before oral anticoagulants.

A new device for simple and accurate urinary pH testing by the Stone-former patient.

PURPOSE: Urinary pH is an important factor linked to renal stone disease and a useful marker in the treatment of urolithiasis. Although the gold standard for measuring urinary pH utilizes a glass electrode and a pH meter, at present dipstick testing is largely used to estimate urinary pH. However, the accuracy and precision of this method may be insufficient for making clinical decisions in patients with lithiasis. The aim of this study is to describe a new device for urinary pH testing. METHODS: The device includes a pH sensor based on differential measurement of an ISFET-REFET pair. The drawbacks associated with this type of configuration, namely short lifetime and manual fabrication, have been overcome in the prototype. An automatic one point calibration is performed when turning on the system. Two buffer solutions were utilized to determine the intra- and inter-day precision of the device. The pH of 30 fresh human urine samples was measured using a pH-meter, a dipstick and the new electronic device. RESULTS: In some cases, dipstick measurements differed from those of the pH meter by more than 0.40 units, a clinically relevant discrepancy, whereas none of the measurements made with the new electronic device differed from the results of the pH-meter by more than 0.1 pH units. CONCLUSIONS: This new electronic device has the possibility to be used by stone-formers to control their urinary pH at home, increasing the tools available for stone prevention and prophylaxis.

Auditory dysfunction.

Hearing impairment, although uncommon, may occur in patients with a vertebrobasilar artery occlusion disease. The pathogenesis may be an ischemic lesion involving the auditory pathways in the pons and midbrain, the cochlear nucleus, cochlear nerve or the cochlea. The AICA and IAA are the main arteries that supply the peripheral audiovestibular structures of the inner ear and central audiovestibular pathways of the middle cerebellar peduncle and lateral pons.