A miniaturized biotelemetric device for the amperometric detection of brain tissue oxygen is presented. The new system, derived from a previous design, has been coupled with a carbon microsensor for the real-time detection of dissolved O 2 in the striatum of freely moving rats. The implantable device consists of a single-supply sensor driver, a current-to-voltage converter, a microcontroller, and a miniaturized data transmitter. The oxygen current is converted to a digital value by means of an analog-to-digital converter integrated in a peripheral interface controller (PIC). The digital data is sent to a personal computer using a six-byte packet protocol by means of a miniaturized 434 MHz amplitude modulation (AM) transmitter. The receiver unit is connected to a personal computer (PC) via a universal serial bus. Custom developed software allows the PC to store and plot received data. The electronics were calibrated and tested in vitro under different experimental conditions and exhibited high stability, low power consumption, and good linear response in the nanoampere current range. The in vivo results confirmed previously published observations on oxygen dynamics in the striatum of freely moving rats. The system serves as a rapid and reliable model for studying the effects of different drugs on brain oxygen and brain blood flow and it is suited to work with direct-reduction sensors or O 2 -consuming biosensors.Oxygen is the most important oxidative substrate for biochemical reactions and for the production of ATP in the brain. Tissue concentration of dissolved O 2 is regulated by the balance between blood supply and local utilization 1 and plays a key role in brain energy metabolism related to either glucose 2 or lactate 3 used as energy substrates.The electrochemical reduction of oxygen is a complex process which can occur on the sensor surface via two mechanisms. In the first, complete reduction occurs in a single step, without the formation of detectable intermediates: 4In the second mechanism, reduction of oxygen occurs in two steps with the formation of hydrogen peroxide as measurable intermediate: 4A wide variety of sensors have been used for direct-reduction of O 2 with the majority of measurements obtained using constant potential amperometry (CPA) at a noble metal microelectrode such gold 5 or platinum. 6 The use of carbon-based electrodes has been reported by several groups 7-9 and often they are preferred to Pt cathodes because of their in vivo stability and less surface poisoning. 9 Moreover, 10 µm Nafion-coated carbon fibers, coupled with fast scan voltammetry (FCV), have been used for the measurement of dissolved oxygen with a subsecond time resolution. 8 However, as previously discussed, 9 the ideal sensor size has to be greater than the dimension of blood capillaries (∼100 µm) for preventing direct blood sampling of dissolved oxygen. In this article we present a new oxygen sensor geometry (conical) particularly suited for in vivo applications, minimizing the tissue trauma related to the stereot...

In this study we present the real-time monitoring of three key brain neurochemical species in conscious rats using implantable amperometric electrodes interfaced to a biotelemetric device. The new system, derived from a previous design, was coupled with carbon-based microsensors and a platinum-based biosensor for the detection of ascorbic acid (AA), O2 and glucose in the striatum of untethered, freely-moving rats. The miniaturized device consisted of a single-supply sensor driver, a current-to-voltage converter, a microcontroller and a miniaturized data transmitter. The redox currents were digitized to digital values by means of an analog-to-digital converter integrated in a peripheral interface controller (PIC), and sent to a personal computer by means of a miniaturized AM transmitter. The electronics were calibrated and tested in vitro under different experimental conditions and exhibited high stability, low power consumption and good linear response in the nanoampere current range. The in-vivo results confirmed previously published observations on striatal AA, oxygen and glucose dynamics recorded in tethered rats. This approach, based on simple and inexpensive components, could be used as a rapid and reliable model for studying the effects of different drugs on brain neurochemical systems.

Mastitis due to intramammary infections is one of the most detrimental diseases in dairy sheep farming, representing a major cause of reduced milk productions and quality losses. In particular, subclinical mastitis presents significant detection and control problems, and the availability of tools enabling its timely, sensitive, and specific detection is therefore crucial. We have previously demonstrated that cathelicidins, small proteins implicated in the innate immune defense of the host, are specifically released in milk of mastitic animals by both epithelial cells and neutrophils. Here, we describe the development of an ELISA for milk cathelicidin and assess its value against somatic cell counts (SCC) and bacteriological culture for detection of ewe mastitis. Evaluation of the cathelicidin ELISA was carried out on 705 half-udder milk samples from 3 sheep flocks enrolled in a project for improvement of mammary health. Cathelicidin was detected in 35.3% of milk samples (249/705), and its amount increased with rising SCC values. The cathelicidin-negative (n=456) and cathelicidin-positive (n=249) sample groups showed a clear separation in relation to SCC, with median values of 149,500 and 3,300,000 cells/mL, respectively. Upon bacteriological culture, 20.6% (145/705) of the milk samples showed microbial growth, with coagulase-negative staphylococci being by far the most frequent finding. A significant proportion of all bacteriologically positive milk samples were positive for cathelicidin (110/145, 75.9%). Given the lack of a reliable gold standard for defining the true disease status, sensitivity (Se) and specificity (Sp) of the cathelicidin ELISA were assessed by latent class analysis against 2 SCC thresholds and against bacteriological culture results. At an SCC threshold of 500,000 cells/mL, Se and Sp were 92.3 and 92.3% for cathelicidin ELISA, 89.0 and 94.9% for SCC, and 39.4 and 93.6% for bacteriological culture, respectively. At an SCC threshold of 1,000,000 cells/mL, Se and Sp were 93.3 and 91.9% for cathelicidin ELISA, 80.0 and 97.1% for SCC, and 39.4 and 93.5% for bacteriology, respectively. In view of the results obtained in this study, the measurement of cathelicidin in milk by ELISA can provide added Se while maintaining a high Sp and may therefore improve detection of subclinical mastitis.

A new embedded telemetry system for amperometric biosensor application is presented. The device consists of a single-supply miniature potentiostat-I/V converter, a microcontroller unit (MCU), a signal transmitter, and a stabilized power supply. The sensor current is converted to a digital value using a peripheral interface controller (PIC) MCU with an integrated analog-to-digital converter (ADC). The PIC firmware is developed in assembly and transferred to the MCU through an in-circuit-serial-programmer (ICSP). The digital data are sent to a personal computer using a miniaturized 433.92 MHz amplitude modulation (AM) transmitter with a linear range up to 30 m. The radio receiver is connected to a PC via a Universal Serial Bus (USB). Custom developed software, written in C and Basic, allows the PC to record, plot and handle the received data. The design, construction and operation of the hardware and software are described. The system performance was evaluated in vitro using a dummy cell and a platinum (Pt) amperometric glucose biosensor. This device serves as a basic model to realize an in vivo, low-cost, miniaturized telemetry system built with standard hardware components readily available.

From 1957 to 1980 in Sardinia, 182 cases of ALS with a mean annual incidence of 0.51 per 100,000 inhabitants and a prevalence rate of 3.65 per 100,000 inhabitants (prevalence day 21.10.1971) were observed. The disease was found to be more common in males, in subjects aged 50 to 70 years and in farmers and shepherds. Incidence in various areas of the island was found to be different. The common form was more frequent, had earlier onset and greater median survival rate.

Ascorbic acid (AA), one of the principal micronutrients in horticultural crops, plays a key role in the human metabolism, and its determination in food products has a great significance. Citrus fruits are rich in AA, but its content is highly susceptible to change during postharvest processing and storage. We present a new ultralow-cost system, constituted of an amperometric microsensor composed of three rod carbon electrodes connected to a telemetric device, for online detection of AA in orange juice, as an alternative to conventional analytical methods. The in vitro calibration, ranged from 0 to 5 mM, and AA juice content was calculated by adding low volumes of sample into an acetate buffer solution at a constant potential of +120 mV vs carbon pseudoreference. This new approach, which is simple, expandable, and inexpensive, seems appropriate for large scale commercial use.

Mastitis due to intramammary infection is one of the most economically relevant diseases in dairy cows, causing reductions in milk quality and quantity. Currently, mastitis monitoring is based on somatic cell count (SCC) and bacteriologic culture (BC) of milk. Nevertheless, inflammation-specific protein markers might provide more sensitive and reliable assays, enabling immunoassay-based screening strategies. Cathelicidin is an inflammatory protein released in milk that has recently demonstrated fair reliability and diagnostic potential for ewe mastitis. To assess its performance in cows, 531 quarter milk samples from 2 herds were tested using cathelicidin ELISA, SCC, and BC. We found that 29.0% of samples were positive for cathelicidin, 18.8% had SCC >200,000 cells/mL, and 13.7% were BC-positive. Cathelicidin showed a strong positive correlation with SCC as demonstrated by receiver operating characteristics curve analysis and by the clustering of cathelicidin-negative and cathelicidin-positive samples in association with low and high SCC values, respectively. For evaluating the diagnostic performance of a novel test, BC cannot be considered a reliable gold standard for true disease status because of its known limitations. Therefore, we assessed the sensitivity (Se) and specificity (Sp) of the milk cathelicidin ELISA using a latent class analysis approach together with BC and SCC by considering different diagnostic thresholds to identify the preferred Se/Sp combination. We modeled conditional dependence of cathelicidin and SCC to account for their close association. The cathelicidin ELISA showed higher Se than SCC and BC for almost all threshold combinations. In fact, at the best-performing threshold combination, the Se of cathelicidin was 80.6%, 6.2 percentage points higher than that of SCC >200,000 cells/mL (74.4%) and similar to that of SCC >100,000 cells/mL (80.2%). Most importantly, this Se was obtained with a loss in Sp of only 1.4 percentage points compared with SCC >200,000 cells/mL (94.9% Sp for cathelicidin vs. 96.3% for SCC >200,000). The limited Se of BC (38.8%) was also confirmed in this study, and BC showed a slightly lower Sp than both cathelicidin and SCC for most of threshold combinations. This study confirmed that cathelicidin is released in the milk of cows with mastitis and that its presence is highly correlated with SCC. The measurement of cathelicidin by ELISA may hold significant potential for improving the sensitivity of mastitis detection in dairy cows while maintaining high specificity.

Molecular biomarkers are very important in biology, biotechnology and even in medicine, but it is quite hard to convert biology-related signals into measurable data. For this purpose, amperometric biosensors have proven to be particularly suitable because of their specificity and sensitivity. The operation and shelf stability of the biosensor are quite important features, and storage procedures therefore play an important role in preserving the performance of the biosensors. In the present study two different designs for both glucose and lactate biosensor, differing only in regards to the containment net, represented by polyurethane or glutharaldehyde, were studied under different storage conditions (+4, −20 and −80 °C) and monitored over a period of 120 days, in order to evaluate the variations of kinetic parameters, as VMAX and KM, and LRS as the analytical parameter. Surprisingly, the storage at −80 °C yielded the best results because of an unexpected and, most of all, long-lasting increase of VMAX and LRS, denoting an interesting improvement in enzyme performances and stability over time. The present study aimed to also evaluate the impact of a short-period storage in dry ice on biosensor performances, in order to simulate a hypothetical preparation-conservation-shipment condition.