Examining the Potential Formation of Ternary DNA Complexes with Chromium­Cysteine, Chromium-Ascorbate, and Chromium-Glutathione and Implications for Their Carcinogenicity.

The mutagenic and carcinogenic properties of chromium(VI) complexes have been ascribed to the formation of ternary Cr(III)-small molecule-DNA complexes. As part of these laboratories' efforts to establish the structure and properties of discrete binary and ternary adducts of Cr(III) and DNA at a molecular level, the properties of Cr(III)-cysteine-DNA, Cr(III)-ascorbate-DNA, and Cr(III)-glutathione-DNA complexes formed from Cr(III) were examined. These studies determined the composition of previously described "pre-reacted" chromium cysteinate and chromium glutathione. Neither of these complexes nor "chromium ascorbate" form ternary complexes with DNA as previously proposed. In fact, these Cr(III) compounds do not measurably bind to DNA and cannot be responsible for the mutagenic and carcinogenic properties ascribed to ternary Cr(III)-cysteine-DNA and Cr(III)-ascorbate-DNA adducts. The results of biological studies where "ternary adducts" of Cr(III), cysteine, glutathione, or ascorbate and DNA were made from "pre-reacted" chromium cysteinate or chromium glutathione or from "chromium ascorbate" must, therefore, be interpreted with caution.

Managing an adult CF population in the COVID-19 pandemic-1 year on.

BACKGROUND: The advent of the COVID-19 pandemic in 2020 required an alteration in the routine care of people with CF (pwCF), deemed to be extremely vulnerable. AIM: We wished to report the alterations in clinical practice, including the introduction of remote video-assisted clinics, made to manage the adult pwCF attending our large centre. METHODS: We studied clinical records over a period of 2 years (March 2019 to February 2021) by comparing 19th March to 20th February (Y1) with 20th March to 21st February (Y2). RESULTS: We have shown out of hospital Multi Disciplinary Team (MDT) support increased and a greater proportion of IV therapy was administered at home. The VAC model of care increased clinical activity while reducing clinic non-attendance rates, suggesting more individuals engage with their carers. CONCLUSIONS: This new model of care has allowed greater engagement with pwCF.

Task Sharing or Task Dumping: Counsellors Experiences of Delivering a Psychosocial Intervention for Mental Health Problems in South Africa.

Given task-sharing mental health counselling to non-specialist providers is a recognised strategy to increase service capacity, ensuring that their training, supervision, and support needs are met is necessary to facilitate the sustainable delivery of a high-quality service. Using in-depth interviews, we qualitatively explored the experiences of 18 facility-based counsellors (FBCs) tasked with delivering a counselling intervention within chronic disease services offered within primary care facilities participating in the project MIND cluster randomised controlled trial. Findings show that project MIND training with a strong emphasis on role playing and skills rehearsal improved FBCs' confidence and competence, complemented by highly structured supervision and debriefing provided by a registered counsellor, were key strategies for supporting the implementation of task-shared mental health counselling. FBCs perceived many benefits to providing mental health counselling in primary healthcare but systemic interventions are needed for sustained implementation.

How benchmarking promotes farmer and veterinarian cooperation to improve calf welfare.

Little is known about the combination of factors that motivate changes in calf management on dairy farms. Providing information to farmers may help promote change, but it is unclear how this approach affects and is affected by the farmer's relationship with the advisors such as the herd veterinarian. The goal of this study was to understand how benchmarking measures related to calf immune development and growth affected farmer and veterinarian cooperation and influenced the farmer's view of the veterinarian as an advisor for calf management. Veterinarians provided their clients (n = 18 dairy farms in the lower Fraser Valley of British Columbia) with 2 benchmark reports providing information on transfer of passive immunity and calf growth. Farmers were interviewed before and after receiving these reports to understand how they perceived their veterinarian as a calf advisor. Qualitative analysis identified 2 major themes indicating that benchmarking (1) improved farmer perception of their veterinarian's capacities to advise on calves and (2) strengthened the social influence of the veterinarian. We conclude that benchmarking can help promote stronger relationships between farmers and veterinarians.

Canadian dairy cattle veterinarian perspectives on calf welfare.

As advisors to dairy farmers, veterinarians are ideally positioned to influence the health of the dairy herd. Recent studies have demonstrated that dairy cattle veterinarians are also concerned about animal welfare, specifically on issues related to the housing environment, painful conditions and procedures, and managing disease in adult animals. However, less is known regarding their perspectives on calf welfare. The goal of this study was to engage cattle veterinarians in an in-depth discussion to gain a better understanding of what they think about calf welfare, and to provide clarity on what they feel is their responsibility to improve the welfare of dairy calves. Focus groups (n = 5), that collectively had 33 participants representing 5 Canadian provinces and different geographical regions, were conducted as part of a continuing education workshop for Canadian cattle veterinarians. Two trained individuals undertook exploratory data analysis using applied thematic analysis, where initial themes were identified and used to develop a detailed codebook to further guide the coding process. All transcripts were coded twice to test the validity of the initial codes and themes. Four major themes were identified: (1) veterinarians prioritized calf health and traded off this issue for other issues such as the calf's social needs; additionally, concerns included nutrition, hunger, and bull calf management; (2) veterinarians see their role in improving calf welfare within the context of shifting norms of calf management, believed to be consequence of pressure from within their profession, but also arising from pressure from their clients and the public; (3) veterinarians see their role as one of exerting social influence, primarily as an educator of their clients; and finally, (4) veterinarians see their responsibility in improving calf welfare as shaped by their personal values and professional ethics. Our results indicate that the veterinarians participating in this study are concerned about a range of calf welfare issues, believe they should have a more active role in calf management on farms, and see their role in improving calf welfare as shaped by their own values, the needs of their clients, and the concerns of the public.

CMT subtypes and disease burden in patients enrolled in the Inherited Neuropathies Consortium natural history study: a cross-sectional analysis.

BACKGROUND: The international Inherited Neuropathy Consortium (INC) was created with the goal of obtaining much needed natural history data for patients with Charcot-Marie-Tooth (CMT) disease. We analysed clinical and genetic data from patients in the INC to determine the distribution of CMT subtypes and the clinical impairment associated with them. METHODS: We analysed data from 1652 patients evaluated at 13 INC centres. The distribution of CMT subtypes and pathogenic genetic mutations were determined. The disease burden of all the mutations was assessed by the CMT Neuropathy Score (CMTNS) and CMT Examination Score (CMTES). RESULTS: 997 of the 1652 patients (60.4%) received a genetic diagnosis. The most common CMT subtypes were CMT1A/PMP22 duplication, CMT1X/GJB1 mutation, CMT2A/MFN2 mutation, CMT1B/MPZ mutation, and hereditary neuropathy with liability to pressure palsy/PMP22 deletion. These five subtypes of CMT accounted for 89.2% of all genetically confirmed mutations. Mean CMTNS for some but not all subtypes were similar to those previously reported. CONCLUSIONS: Our findings confirm that large numbers of patients with a representative variety of CMT subtypes have been enrolled and that the frequency of achieving a molecular diagnosis and distribution of the CMT subtypes reflects those previously reported. Measures of severity are similar, though not identical, to results from smaller series. This study confirms that it is possible to assess patients in a uniform way between international centres, which is critical for the planned natural history study and future clinical trials. These data will provide a representative baseline for longitudinal studies of CMT. CLINICAL TRIAL REGISTRATION: ID number NCT01193075.

Signal detection in animal psychoacoustics: analysis and simulation of sensory and decision-related influences.

Signal detection theory (SDT) provides a framework for interpreting psychophysical experiments, separating the putative internal sensory representation and the decision process. SDT was used to analyse ferret behavioural responses in a (yes-no) tone-in-noise detection task. Instead of measuring the receiver-operating characteristic (ROC), we tested SDT by comparing responses collected using two common psychophysical data collection methods. These (Constant Stimuli, Limits) differ in the set of signal levels presented within and across behavioural sessions. The results support the use of SDT as a method of analysis: SDT sensory component was unchanged between the two methods, even though decisions depended on the stimuli presented within a behavioural session. Decision criterion varied trial-by-trial: a 'yes' response was more likely after a correct rejection trial than a hit trial. Simulation using an SDT model with several decision components reproduced the experimental observations accurately, leaving only ∼10% of the variance unaccounted for. The model also showed that trial-by-trial dependencies were unlikely to influence measured psychometric functions or thresholds. An additional model component suggested that inattention did not contribute substantially. Further analysis showed that ferrets were changing their decision criteria, almost optimally, to maximise the reward obtained in a session. The data suggest trial-by-trial reward-driven optimization of the decision process. Understanding the factors determining behavioural responses is important for correlating neural activity and behaviour. SDT provides a good account of animal psychoacoustics, and can be validated using standard psychophysical methods and computer simulations, without recourse to ROC measurements.

Location of cells giving phase-locked responses to pure tones in the primary auditory cortex.

Phase-locked responses to pure tones have previously been described in the primary auditory cortex (AI) of the guinea pig. They are interesting because they show that some cells may use a temporal code for representing sounds of 60-300 Hz rather than the rate or place mechanisms used over most of AI. Our previous study had shown that the phase-locked responses were grouped together, but it was not clear whether they were in separate minicolumns or a larger macrocolumn. We now show that the phase-locked cells are arranged in a macrocolumn within AI that forms a subdivision of the isofrequency bands. Phase-locked responses were recorded from 158 multiunits using silicon based multiprobes with four shanks. The phase-locked units gave the strongest response in layers III/IV but phase-locked units were also recorded in layers II, V and VI. The column included cells with characteristic frequencies of 80 Hz-1.3 kHz (0.5-0.8 mm long) and was about 0.5 mm wide. It was located at a constant position at the intersection of the coronal plane 1 mm caudal to bregma and the suture that forms the lateral edge of the parietal bone.

Neuronal spike-train responses in the presence of threshold noise.

The variability of neuronal firing has been an intense topic of study for many years. From a modelling perspective it has often been studied in conductance based spiking models with the use of additive or multiplicative noise terms to represent channel fluctuations or the stochastic nature of neurotransmitter release. Here we propose an alternative approach using a simple leaky integrate-and-fire model with a noisy threshold. Initially, we develop a mathematical treatment of the neuronal response to periodic forcing using tools from linear response theory and use this to highlight how a noisy threshold can enhance downstream signal reconstruction. We further develop a more general framework for understanding the responses to large amplitude forcing based on a calculation of first passage times. This is ideally suited to understanding stochastic mode-locking, for which we numerically determine the Arnol'd tongue structure. An examination of data from regularly firing stellate neurons within the ventral cochlear nucleus, responding to sinusoidally amplitude modulated pure tones, shows tongue structures consistent with these predictions and highlights that stochastic, as opposed to deterministic, mode-locking is utilised at the level of the single stellate cell to faithfully encode periodic stimuli.

Calcium window currents, periodic forcing, and chaos: understanding single neuron response with a discontinuous one-dimensional map.

Thalamocortical (TC) neurones are known to express the low-voltage activated, inactivating Ca2+ current I(T). The triggering of this current underlies the generation of low threshold Ca2+ potentials that may evoke single or bursts of action potentials. Moreover, this current can contribute to an intrinsic slow (<1 Hz) oscillation whose rhythm is partly determined by the steady state component of I(T) and its interaction with a leak current. This steady state, or window current as it is so often called, has received relatively little theoretical attention despite its importance in determining the electroresponsiveness and input-output relationship of TC neurones. In this paper, we introduce an integrate-and-fire spiking neuron model that includes a biophysically realistic model of I(T). We briefly review the subthreshold bifurcation diagram of this model with constant current injection before moving on to consider its response to periodic forcing. Direct numerical simulations show that as well as the expected mode-locked responses there are regions of parameter space that support chaotic behavior. To reveal the mechanism by which the window current generates a chaotic response to periodic forcing we consider a piecewise linear caricature of the dynamics for the gating variables in the model of I(T). This model can be analyzed in closed form and is shown to support an unstable set of periodic orbits. Trajectories are repelled from these organizing centers until they reach the threshold for firing. By determining the condition for a grazing bifurcation (at the border between a spiking and nonspiking event) we show how knowledge of the unstable periodic orbits (existence and stability) can be combined with the grazing condition to determine an effective one-dimensional map that captures the essentials of the chaotic behavior. This map is discontinuous and has strong similarities with the universal limit mapping in grazing bifurcations derived in the context of impacting mechanical systems [A. B. Nordmark, Phys. Rev. E 55, 266 (1997)].

Some investigations into non-passive listening.

Our knowledge of the function of the auditory nervous system is based upon a wealth of data obtained, for the most part, in anaesthetised animals. More recently, it has been generally acknowledged that factors such as attention profoundly modulate the activity of sensory systems and this can take place at many levels of processing. Imaging studies, in particular, have revealed the greater activation of auditory areas and areas outside of sensory processing areas when attending to a stimulus. We present here a brief review of the consequences of such non-passive listening and go on to describe some of the experiments we are conducting to investigate them. In imaging studies, using fMRI, we can demonstrate the activation of attention networks that are non-specific to the sensory modality as well as greater and different activation of the areas of the supra-temporal plane that includes primary and secondary auditory areas. The profuse descending connections of the auditory system seem likely to be part of the mechanisms subserving attention to sound. These are generally thought to be largely inactivated by anaesthesia. However, we have been able to demonstrate that even in an anaesthetised preparation, removing the descending control from the cortex leads to quite profound changes in the temporal patterns of activation by sounds in thalamus and inferior colliculus. Some of these effects seem to be specific to the ear of stimulation and affect interaural processing. To bridge these observations we are developing an awake behaving preparation involving freely moving animals in which it will be possible to investigate the effects of consciousness (by contrasting awake and anaesthetized), passive and active listening.

SMN mRNA and protein levels in peripheral blood: biomarkers for SMA clinical trials.

BACKGROUND: Clinical trials of drugs that increase SMN protein levels in vitro are currently under way in patients with spinal muscular atrophy. OBJECTIVE: To develop and validate measures of SMN mRNA and protein in peripheral blood and to establish baseline SMN levels in a cohort of controls, carriers, and patients of known genotype, which could be used to follow response to treatment. METHODS: SMN1 and SMN2 gene copy numbers were determined in blood samples collected from 86 subjects. Quantitative reverse transcription PCR was used to measure blood levels of SMN mRNA with and without exon 7. A cell immunoassay was used to measure blood levels of SMN protein. RESULTS: Blood levels of SMN mRNA and protein were measured with high reliability. There was little variation in SMN levels in individual subjects over a 5-week period. Levels of exon 7-containing SMN mRNA and SMN protein correlated with SMN1 and SMN2 gene copy number. With the exception of type I SMA, there was no correlation between SMN levels and disease severity. CONCLUSION: SMN mRNA and protein levels can be reliably measured in the peripheral blood and used during clinical trials in spinal muscular atrophy, but these levels do not necessarily predict disease severity.

Adult botulism type F in the United States, 1981-2002.

BACKGROUND: Clostridium botulinum neurotoxin types A, B, and E cause most cases of the paralytic disease botulism. Little is known about the epidemiology, clinical features, or microbiology of botulism type F. METHODS: Cases of adult type F botulism were identified by review of data collected by CDC's National Botulism Surveillance System between 1981 and 2002. A case was either an individual whose serum or stool demonstrated type F toxin or whose stool culture yielded an organism producing toxin type F. A detailed review of cases' medical charts and laboratory data from CDC and local health departments was performed. RESULTS: Between 1981 and 2002, 1,269 cases of botulism among adults and infants were reported to CDC; 13 (1%) were adult type F. The median age of type F cases was 54 years; 7 (54%) were female. None were part of outbreaks. A toxigenic Clostridium baratii was identified in 9 (69%) of 13 cases. Among 11 cases for which clinical data were available, all required mechanical ventilation for a median duration of 17 days (range, 10 to 84); 8 (73%) were intubated within 24 hours of symptom onset. All patients had nearly complete or complete quadriplegia at the nadir of neurologic dysfunction, which occurred on average on day 5. On average by day 8, improvement in neuromuscular function was noted. The median duration of acute hospitalization was 31 days (range, 20 to 60). No deaths were reported. In only one case was a possible foodborne etiology identified. CONCLUSIONS: Toxigenic C baratii are the sole documented causes of type F botulism in the United States since 1981. These cases are characterized by a fulminant course with rapid progression to respiratory failure and paralysis, making early recognition and intervention critical to appropriate management.

Effects of contralateral sound stimulation on unit activity of ventral cochlear nucleus neurons.

The cochlear nucleus (CN) commissural connection represents the first opportunity for convergence of binaural information in the auditory brainstem. All major neuron types in the ventral CN (VCN) are innervated by a diverse population of cells in the contralateral VCN. This study examined the effect of contralateral sound stimulation on the spontaneous rates (SRs) of neurons in the VCN. Unit activity was recorded with silicon-substrate multichannel probes which allowed recordings from up to 16 sites simultaneously. On average, 30% of units showed short-latency (often only 2 ms greater than the latencies of ipsilateral sound-evoked responses) inhibition of SR by wideband contralateral noise bursts. Fewer units (4.5%) were excited by contralateral noise at sound levels low enough to exclude excitation by acoustic crossover. Both regular and irregular units in the anterior VCN (AVCN) and posterior VCN (PVCN) were inhibited by contralateral sound. Decrements in SR followed a monotonic function with increases in contralateral sound level, except where responses could be attributed to acoustic crossover. Restricting the contralateral noise bandwidth resulted in a frequency-specific inhibition, dominated by frequencies at and below the ipsilateral BF of the unit, consistent with anatomical findings of the tonotopic organization of the CN commissural pathway. The latencies of these effects are compatible with mono, di and tri-synaptic connections reflecting CN commissural pathway effects.

The spectrum of neuropathy in diabetes and impaired glucose tolerance.

OBJECTIVE: To compare the neuropathy associated with impaired glucose tolerance (IGT) and diabetes mellitus (DM) determined by oral glucose tolerance testing (OGTT). METHODS: Patients with peripheral neuropathy of unknown cause were prescribed OGTT. Duration of neuropathic symptoms, neuropathic pain, neuropathy classification, nerve conduction test results, and intraepidermal nerve fiber densities (IENFD) were compared between IGT and DM groups. RESULTS: Seventy-three patients completed OGTT; 41 (56%) had abnormal results. Of these 41 patients, 26 had IGT and 15 had DM. Patients with IGT had less severe neuropathy than patients with diabetes, as measured by sural nerve amplitudes (p = 0.056), sural nerve conduction velocities (p = 0.03), and distal leg IENFD (p = 0.01). Patients with IGT had predominantly small fiber neuropathy, compared to patients with DM (p = 0.05), who had more involvement of large nerve fibers. CONCLUSIONS: The neuropathy associated with IGT is milder than the neuropathy associated with DM. Small nerve fibers are prominently affected and may be the earliest detectable sign of neuropathy in glucose dysmetabolism. OGTT is appropriate in patients with idiopathic neuropathy.

Biosensor based on enzyme-catalysed degradation of thin polymer films.

A biosensor based on the enzyme-catalysed dissolution of biodegradable polymer films has been developed. Three polymer-enzyme systems were investigated for use in the sensor: a poly(ester amide), which is degraded by the proteolytic enzyme alpha-chymotrypsin; a dextran hydrogel, which is degraded by dextranase; and poly(trimethylene) succinate, which is degraded by a lipase. Dissolution of the polymer films was monitored by Surface Plasmon Resonance (SPR). The rate of degradation was directly related to enzyme concentration for each polymer/enzyme couple. The poly(ester amide)/alpha-chymotrypsin couple proved to be the most sensitive over a concentration range from 4 x 10(-11) to 4 x 10(-7) mol l(-1) of enzyme. The rate of degradation was shown to be independent of the thickness of the poly(ester amide) films. The dextran hydrogel/dextranase couple was less sensitive than the poly(ester amide)/alpha-chymotrypsin couple but showed greater degradation rates at low enzyme concentrations. Enzyme concentrations as low as 2 x 10(-11) mol l(-1) were detected in less than 20 min. Potential fields of application of such a sensor system are the detection of enzyme concentrations and the construction of disposable enzyme based immunosensors, which employ the polymer-degrading enzyme as an enzyme label.

Telepsychiatry: challenges in rural aging.

A significant health care dilemma for older individuals living in rural areas is that at a time in life when there is, predictably, a greater need for medical services, the ability to access those limited services is markedly reduced. Telepsychiatry presents an innovative and cost-effective strategy for the provision of improved local access to quality mental health services for the underserved rural elderly. Telepsychiatry has demonstrated the potential to improve access to mental health services, provide those services in an affordable and cost-effective manner and deliver those services at a quality nearly equal to traditional face-to-face services. Advances in telepsychiatry technology allow a core group of skilled mental health providers in a central location to provide timely local access to quality services for the rural elderly over a broad geographic area.

A transducer based on enzyme-induced degradation of thin polymer films monitored by surface plasmon resonance.

A novel transducer based on the dissolution of biodegradable polymer films as a direct result of enzymatic reaction has been developed. Three polymers were investigated for use in the transducer: a poly(ester amide), which is degraded by the proteolytic enzyme alpha-chymotrypsin; a dextran hydrogel, which is degraded by dextranase; and poly(trimethylene) succinate, which is degraded by a lipase. Degradation of the polymer films was monitored by surface plasmon resonance (SPR) and impedance measurements. SPR was shown to be suitable for a greater variety of materials, since it does not require the polymer film to be electrically insulating. Rate of degradation was shown to be directly related to enzyme concentration for each polymer/enzyme couple. The poly(ester amide)/alpha-chymotrypsin couple proved to be the most sensitive. Degradation of the films was complete in less than 20 min for enzyme concentrations greater than 9 x 10(-9) mol dm-3. Enzyme concentrations as low as 4 x 10(-11) mol dm-3 were detected in less than 30 min. The transducer has great potential for the detection of enzyme concentrations as well as for use in immunosensing where the enzyme degrading the polymer would be the enzyme label.