FDA trial regulation of laboratory developed tests (LDTs): An academic medical center's experience with Mpox in-house testing

The 2022 mpox outbreak presented a familiar challenge to clinical laboratories. Accordingly, our institution was able to swiftly implement in-house mpox testing to meet the imminent diagnostic needs of the public health emergency. While the FDA authorized laboratory-developed tests (LDTs) for lesion specimens, however, it restricted the testing of rectal swabs despite mounting evidence of its clinical utility. Notably, within the short timeframe when rectal testing was available, we identified a high-risk patient without apparent lesions who tested monkeypox-positive only by our in-house rectal swab assay. In order for our institution to continue testing non-lesion samples, The FDA required a separate Emergency Use Authorization (EUA) application that demanded additional resource-costly validation studies despite utilizing the same testing platform as lesion samples. Here, we provide a brief review of the history, current status, and legal scope surrounding LDT validations, with an in-depth comparison of the technical requirements by CLIA, CAP and the FDA. Importantly, we provide our experience with the mpox EUA submission process to serve as context for the challenges that may be imposed by the new FDA regulations. We hope that our experience will offer a valuable perspective that promotes constructive discourse towards addressing the imperative to offer high-quality laboratory diagnostics without compromising on the need of the medical laboratory community to provide effective patient care.

Endoparasite loads and the efficacy of conventional anthelmintics against gastrointestinal nematodes in captive European bison

Although little information exists on the efficacy of deworming in wild ruminants, gastrointestinal nematodes have been found to demonstrate increasing drug resistance. The spread of drug-resistant strains may be increased by transmission among livestock and susceptible wildlife species, thus posing a potential threat to endangered species, such as the European bison. The aim of the study was twofold: to identify the parasite loads in captive European bison with the use of coprological techniques, and to test the influence of other nearby ungulates on the richness of bison parasitofauna. Additionally, the efficacy of deworming procedures against gastrointestinal nematodes in bison was evaluated. The survey was based on a coprological investigation of 285 fecal samples from 156 European bison in 15 enclosures. The parasitofauna of the captive European bison was consistent with those of free-ranging populations. The highest prevalence was noted for Eimeria spp. oocysts (60.7%), strongyle eggs (50.9%), Fasciola hepatica eggs (13.1%), Dictyocaulus viviparus larvae (12.3%) and Trichuris sp. Eggs (9.47%). Moreover, the close proximity of other ungulate species resulted in a higher diversity of parasite species. In all cases, deworming with albendazole, fenbendazole and ivermectin proved to be ineffective against strongylids and Trichuris sp. The results of fecal egg count reduction test (FECRT) ranged from 37.2 to 99.6% (95% CI <90%) for albendazole; values >95% (95% CI = 41-100) were noted for fenbendazole, and FECRT ranged from 63.2 to 97.5 (95% CI = 0-99) for ivermectin. As the results of anthelmintic treatment are unsatisfactory, it seems justified to continue study in this area. Our study is the first large-scale attempt to evaluate the efficacy of anthelminthics in captive European bison. The potential sharing of parasite species between bison and other ungulates should also be further investigated from the perspective of minimizing the risk of the spread of drug-resistant parasite strains.

Impact of the loss of Laboratory Developed Mass Spectrometry testing at a major academic medical center

Background

Our laboratory historically performed immunosuppressant and definitive opioid testing in-house as laboratory developed (LDT) mass spectrometry-based tests. However, staffing constraints and supply chain challenges associated with the COVID-19 pandemic forced us to refer this testing to a national reference laboratory. The VALID Act could impose onerous requirements for laboratories to develop LDTs. To explore the potential effect of these additional regulatory hurdles, we used the loss of our own LDT tests to assess the impact on patient care and hospital budgets.

Methods

Laboratory information systems data and historical data associated with test costs were used to calculate turnaround times and financial impact.

Results

Referral testing has extended the reporting of immunosuppressant results by an average of approximately one day and up to two days at the 95th percentile. We estimate that discontinuing in-house opioid testing has cost our health system over half a million dollars in the year since testing was discontinued.

Conclusions

Barriers that discourage laboratories from developing in-house testing, particularly in the absence of FDA-cleared alternatives, can be expected to have a detrimental effect on patient care and hospital finances.

Impact of VALID Act implementation on mass spectrometry-based clinical proteomic laboratory developed tests

Mass spectrometry (MS)-based clinical proteomic Laboratory Developed Tests (LDTs) for the measurement of protein biomarkers related to endocrinology, cardiovascular disease, cancer, and Alzheimer's disease are gaining traction in clinical laboratories due to their value in supporting diagnostic and treatment decisions for patients. Under the current regulatory landscape, MS-based clinical proteomic LDTs are regulated by Clinical Laboratory Improvement Amendments (CLIA) under the auspices of the Centers for Medicaid and Medicare Services (CMS). However, should the Verifying Accurate Leading-Edge In Vitro Clinical Test Development (VALID) Act pass, it will grant the FDA greater authority to oversee diagnostic tests, including LDTs. This could impede clinical laboratories' ability to develop new MS-based proteomic LDTs to support existing and emerging patient care needs. Therefore, this review discusses the currently available MS-based proteomic LDTs and their current regulatory landscape in the context of the potential impacts imposed by the passage of the VALID Act.

Determining PD-L1 expression in head and neck squamous cell carcinoma using immunohistochemistry

Background

Advanced head and neck squamous cell carcinoma (HNSCC) has limited treatment options. Programmed death-ligand1 (PD-L1) expressed by tumor cells interacts with PD-1 receptor on T lymphocytes leading to immune evasive response and survival advantage. Therapy with immune check-point inhibitors target PD-1/PD-L1 blockade inducing tumor regression. Immunohistochemistry (IHC) for PD-L1 expression enables patient selection for immunotherapy and may be considered a potential predictor of clinical response.

Methods

A retrospective analysis of IHC for PD-L1 expression using manual laboratory developed technique (LDT) with antibody clone 22C3 (Dako) in 93 cases of HNSCC. PD-L1 expression was correlated with age, gender, tumor site, grade and stage.

Results

PD-L1 IHC was performed in 93 cases and immunopositivity was noted in 59 (63.4%) cases. High expression with combined proportion score (CPS) ≥50 was seen in 15 (16.1%) cases and low expression with CPS ≥1 expression was seen in 44 (47.3%) cases. An almost-perfect interobserver agreement was noted by two pathologists for PD-L1 IHC expression (Cohen's kappa coefficient = 0.910). No statistically significant correlation was noted between PD-L1 score and patient demographics, tumor site, grade or stage.

Conclusion

Detection of PD-L1 status by IHC enables identification of HNSCC patients eligible for future targeted immunotherapy.

Laboratory-Developed Tests: Design of a Regulatory Strategy in Compliance with the International State-of-the-Art and the Regulation (EU) 2017/746 (EU IVDR [In Vitro Diagnostic Medical Device Regulation])

PURPOSE

This study aimed at the development of a regulatory strategy for compliance of laboratory-developed tests (LDTs) with requirements of the Regulation (EU) 2017/746 ("EU-IVDR") under consideration of international requirements for LDTs as established in major regulatory regions. Furthermore, it was analysed in how far elements of current LDT regulation could qualify for an internationally harmonised concept ensuring quality, safety and performance of LDTs.

METHODS

A review of regulatory literature including legislation as well as guidance documents was performed. The regulatory strategy was adapted from international guidance concepts used for commercially marketed IVD. It was then applied to the example of a large medical laboratory in the EU. A high-level comparison was conducted to identify gaps and matches between the different international regulatory requirements for LDTs.

RESULTS

A four-step strategy for compliance of LDTs with the EU IVDR was implemented in an exemplary medical laboratory. On the basis of an internationally used LDT definition, LDTs constitute nearly 50% of the total IVD devices used in the laboratory. While an ISO 15189-compliant QMS is a major component, it should be accompanied by the application of appropriate processes for risk management, performance evaluation and continuous monitoring of LDTs. At least six criteria represent common characteristics of a potential, internationally convergent concept for the regulation/standardization of LDTs.

CONCLUSIONS

This study confirms the impact of LDTs for individualized and innovative medical laboratory testing. Prerequisites for LDT use as especially given by the IVDR and missing interpretation in the EU with regard to the scope of LDT definition, the application of standards and the extent of documentation for LDTs currently lead to uncertainties for both laboratories and regulatory bodies responsible for LDT oversight. The characteristics identified as common criteria for ensuring quality, safety and performance of LDTs may be considered as central elements of future international consensus guidance.

Laterodorsal tegmentum-ventral tegmental area projections encode positive reinforcement signals

The laterodorsal tegmentum (LDT) is a brainstem nucleus classically involved in REM sleep and attention, and that has recently been associated with reward‐related behaviors, as it controls the activity of ventral tegmental area (VTA) dopaminergic neurons, modulating dopamine release in the nucleus accumbens. To further understand the role of LDT–VTA inputs in reinforcement, we optogenetically manipulated these inputs during different behavioral paradigms in male rats. We found that in a two‐choice instrumental task, optical activation of LDT–VTA projections shifts and amplifies preference to the laser‐paired reward in comparison to an otherwise equal reward; the opposite was observed with inhibition experiments. In a progressive ratio task, LDT–VTA activation boosts motivation, that is, enhances the willingness to work to get the reward associated with LDT–VTA stimulation; and the reverse occurs when inhibiting these inputs. Animals abolished preference if the reward was omitted, suggesting that LDT–VTA stimulation adds/decreases value to the stimulation‐paired reward. In addition, we show that LDT–VTA optical activation induces robust preference in the conditioned and real‐time place preference tests, while optical inhibition induces aversion. The behavioral findings are supported by electrophysiological recordings and c‐fos immunofluorescence correlates in downstream target regions. In LDT–VTA ChR2 animals, we observed an increase in the recruitment of lateral VTA dopamine neurons and D1 neurons from nucleus accumbens core and shell; whereas in LDT–VTA NpHR animals, D2 neurons appear to be preferentially recruited. Collectively, these data show that the LDT–VTA inputs encode positive reinforcement signals and are important for different dimensions of reward‐related behaviors.

Development and validation of a new triplex real-time quantitative reverse Transcriptase-PCR assay for the clinical detection of SARS-CoV-2

To increase the repertoire of PCR based laboratory developed tests (LDTs) for the detection of SARS-CoV-2, we describe a new multiplex assay (SORP), targeting the SARS-CoV-2's, Spike and ORF8 genes. The widely used human RNaseP internal control was modified to specifically co-amplify the RNaseP mRNA. The SORP triplex assay was tested on a cohort (n = 372; POS = 144/NEG = 228) of nasopharyngeal flocked swab (NPFS) specimens, previously tested for the presence of SARS-CoV-2 using a PCR assay targeting E and RdRp genes. The overall sensitivity and specificity of the SORP assay was: 99.31% (95% CI: 96.22–99.98%), 100.0% (95% CI: 98.4–100%) respectively. The SORP assay could also detect a panel of variants of concern (VOC) from the B1.1.7 (UK) and B1.351 (SA) lineage. In summary, access to a repertoire of new SARS-CoV-2 LDT's would assist diagnostic laboratories in developing strategies to overcome some of the testing issues encountered during high-throughput SARS-CoV-2 testing.

Clinical evaluation of a laboratory-developed quantitative BK virus-PCR assay using the cobas® omni Utility Channel

BACKGROUND

In immunocompromised patients, BK Virus (BKV) reactivation may cause serious disease with high morbidity. Particularly for patient management after solid organ transplantation, monitoring of viral load in different clinical specimens is crucial to ensure early diagnosis and response to reactivation. In this study, we evaluated the clinical performance of a custom designed primer /probe set for detection of BKV on the cobas® 6800, a high-throughput platform, employing the open channel of the system for integration of a lab-developed test (LDT).

MATERIALS/METHODS

A primer/probe set was optimized for the use on a high-throughput platform. Clinical performance was assessed in EDTA-plasma, serum and urine samples. Limit-of-detection (LOD) was determined by using a dilution series of BKV WHO standard. A CE-labeled PCR test (Altona Diagnostics) was used as a comparison to the assay.

RESULTS

The LOD for the LDT BKV assay was 6.7 IU/mL. Inter-and intra-run variability (at 5 x LOD) was low (<1.5 Ct in all specimens). All quality control panel specimens (Instand Germany n = 19) were correctly identified. Of 290 clinical samples tested, results were concordant for 280 samples. Sensitivity and specificity of the assay were 96 % and 98 % respectively. The quantitative analysis revealed a strong correlation (linear regression) between the CE-labelled comparator assay and the new BKV LDT assay with r² = 0.96 for n = 123 urine samples and r² = 0.98 for n = 167 plasma/serum samples.

CONCLUSION

Compared to a CE-IVD assay, the adapted LDT showed good analytical and clinical sensitivity and specificity for the detection and quantification of BKV in different clinical specimens. It represents a convenient solution to automate the LDT workflow with low hands-on time and thus facilitates high-throughput screening for BKV reactivation in immunocompromised patients.

[Impact of the novel in vitro diagnostic regulation (IVDR) of the European Union on pathology laboratories. What's important?]

In 2022 the new in vitro diagnostic regulation (IVDR) of the European Union will come into full effect. This complex regulatory framework aims at a stricter regulation and monitoring of industrial diagnostic assay production. The IVDR defines many new methodological requirements and includes an additional entirely new focus on the clinical validity of diagnostic assays as well as a novel tighter vigilance system. Although not the core of the regulation, the whole field of laboratory developed tests (LDTs) is also subject to fundamental restructuring within this regulatory framework. The respective requirements are broad and will pose many challenges to assay developers and users in pathology. The many new aspects of LDT production and use must be properly addressed to avoid a bottleneck in diagnostic assay availability. In this article, the impact of the different aspects of the IVDR on European pathology laboratories will be discussed.

Electrophysiological and Behavioral Correlates of Valence, Arousal and Subjective Significance in the Lexical Decision Task

The emotional properties of words, such as valence and arousal, influence the way we perceive and process verbal stimuli. Recently, subjective significance was found to be an additional factor describing the activational aspect of emotional reactions, which is vital for the cognitive consequences of emotional stimuli processing. Subjective significance represents the form of mental activation specific to reflective mind processing. The Lexical Decision Task (LDT) is a paradigm allowing the investigation of the involuntary processing of meaning and differentiating this processing from the formal processing of the perceptual features of words. In this study, we wanted to search for the consequences of valence, arousal, and subjective significance for the involuntary processing of verbal stimuli meaning indexed by both behavioral measures (reaction latencies) and electrophysiological measures (Event-Related Potentials: ERPs). We expected subjective significance, as the reflective form of activation, to shorten response latencies in LDT. We also expected subjective significance to modulate the amplitude of the ERP FN400 component, reducing the negative-going deflection of the potential. We expected valence to shape the LPC component amplitude, differentiating between negative and positive valences, since the LPC indexes the meaning processing. Indeed, the results confirmed our expectations and showed that subjective significance is a factor independent from the arousal and valence that shapes the involuntary processing of verbal stimuli, especially the detection of a link between stimulus and meaning indexed by the FN400. Moreover, we found that the LPC amplitude was differentiated by valence level.

Multiplexing primer/probe sets for detection of SARS-CoV-2 by qRT-PCR

BACKGROUND

The novel respiratory virus SARS-CoV-2, responsible for over 380,000 COVID-19 related deaths, has caused significant strain on healthcare infrastructure and clinical laboratories globally. The pandemic's initial challenges include broad diagnostic testing, consistent reagent supply lines, and access to laboratory instruments and equipment. In early 2020, primer/probe sets distributed by the CDC utilized the same fluorophore for molecular detection - requiring multiple assays to be run in parallel - consuming valuable and limited resources.

METHODS

Nasopharyngeal swabs submitted to UW Virology for SARS-CoV-2 clinical testing were extracted, amplified by our laboratory developed test (LDT) - a CDC-based quantitative reverse transcriptase PCR reaction - and analyzed for agreement between the multiplexed assay. Laboratory- confirmed respiratory infection samples were included to evaluate assay cross-reaction specificity.

RESULTS

Triplexing correctly identified SARS-CoV-2 in 98.4% of confirmed positive or inconclusive patient samples by single-plex LDT (n = 183/186). All 170 SARS-CoV-2 negative samples tested by single-plex LDT were negative by triplexing. Other laboratory-confirmed respiratory infections did not amplify for SARS-CoV-2 in the triplex reaction.

CONCLUSIONS

Multiplexing two virus-specific gene targets and an extraction control was found to be comparable to running parallel assays independently, while significantly improving assay throughput.

The Affective Meaning of Words is Constrained by the Conceptual Meaning

To directly investigate the reciprocal causal relationship of the conceptual and affective meaning of words, two priming experiments were conducted with the lexical decision task. In Experiment 1, the influence of semantic relatedness on the affective priming effect was explored by manipulating the semantic associative strength between the prime and target words (i.e., high vs. low) while keeping the affective association between them constant (i.e., affectively congruent). In Experiment 2, the influence of the affective meaning on the semantic priming effect was explored by manipulating the emotional congruency of the prime and target words (i.e., congruent vs. incongruent) while keeping the semantic association between them constant (i.e., high associative strength). The results of Experiment 1 showed that when the semantic associative strength between the prime and target words was high, there was a significant affective priming effect, while no significant affective priming effect was found when the associative strength was low. The results of Experiment 2 revealed that in both the emotionally congruent and incongruent conditions, a significant semantic priming effect was obtained. These findings suggest that conceptual meaning is a more obligatory representation in words and that the processing of the affective meaning is constrained by the conceptual meaning of words.

The FDA-Approved Breast Cancer HER2 Evaluation Kit (HercepTest; Dako) May Miss Some HER2-Positive Breast Cancers

OBJECTIVES

Accurate evaluation of human epidermal growth factor receptor 2 (HER2) in breast cancer is critical.

METHODS

HER2 fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) tests were performed on 52 cases using a US Food and Drug Administration (FDA)-approved kit (HercepTest, FDA kit) and a laboratory-developed test (LDT) with the HercepTest antibody and a Leica Bond automated stainer.

RESULTS

By FISH, 22 were HER2 positive, 29 were negative, and one was equivocal. Of the 22 HER2 FISH-positive cases, five were negative by the FDA kit and none by LDT. The five discrepant cases were retested using the same FDA kit in another Clinical Laboratory Improvement Amendments-certified laboratory, and all five cases were still negative. None of the 29 HER2 FISH-negative cases were positive by the FDA kit or LDT. The overall IHC-FISH concordance rate was 90.4% for the FDA kit and 100% for the LDT.

CONCLUSIONS

The FDA kit may miss some HER2-positive cases. The LDT has a higher sensitivity and a higher concordance rate with FISH results.

Establishing a stable, repeatable platform for measuring changes in sperm DNA methylation

BACKGROUND

Several independent research groups have shown that alterations in human sperm methylation profiles correlate with decreased fecundity and an increased risk of poor embryo development. Moving these initial findings from the lab into a clinical setting where they can be used to measure male infertility though requires a platform that is stable and robust against batch effects that can occur between sample runs. Operating parameters must be established, performance characteristics determined, and guidelines set to ensure repeatability and accuracy. The standard for technical validation of a lab developed test (LDT) in the USA comes from the Clinical Laboratory Improvement Amendments (CLIA). However, CLIA was introduced in 1988, before the advent of genome-wide profiling and associated computational analysis. This, coupled with its intentionally general nature, makes its interpretation for epigenetic assays non-trivial.

RESULTS

Here, we present an interpretation of the CLIA technical validation requirements for profiling DNA methylation and calling aberrant methylation using the Illumina Infinium platform (e.g., the 450HM and MethylationEPIC). We describe an experimental design to meet these requirements, the experimental results obtained, and the operating parameters established.

CONCLUSIONS

The CLIA guidelines, although not intended for high-throughput assays, can be interpreted in a way that is consistent with modern epigenetic assays. Based on such an interoperation, Illumina's Infinium platform is quite amenable to usage in a clinical setting for diagnostic work.

Understanding the Food and Drug Administration's Jurisdiction Over Laboratory-Developed Tests and Divisions Between Food, Drug, and Cosmetic Act-Regulated and Clinical Laboratory Improvement Amendments of 1988-Regulated Activities

The scope of FDA's jurisdiction over laboratory-developed tests (LDTs), and whether FDA has such jurisdiction at all, has been a heavily debated issue over the past several years. If FDA moves forward with its guidance, or Congress takes action to reform LDT and IVD regulation, a fundamental question that needs to be answered is how to divide activities regulated by FDCA from those regulated by CLIA. In this article, we consider FDA's authority to regulate LDTs and the policy implications of regulation, and discuss an idea for a fact-driven framework to distinguish FDCA- and CLIA- activities.

Maintaining Life-saving Testing for Patients With Infectious Diseases: Infectious Diseases Society of America, American Society for Microbiology, and Pan American Society for Clinical Virology Recommendations on the Regulation of Laboratory-developed Tests

In 2014, the US Food and Drug Administration (FDA) proposed to regulate laboratory-developed tests (LDTs)-diagnostics designed, manufactured, and used within a single laboratory. The Infectious Diseases Society of America, the American Society for Microbiology, and the Pan American Society for Clinical Virology recognize that the FDA is committed to protecting patients. However, our societies are concerned that the proposed regulations will limit access to testing and negatively impact infectious diseases (ID) LDTs. In this joint commentary, our societies discuss why LDTs are critical for ID patient care, hospital infection control, and public health responses. We also highlight how the FDA's proposed regulation of LDTs could impair patient access to life-saving tests and stifle innovation in ID diagnostics. Finally, our societies make specific recommendations for the FDA's consideration to reduce the burden of the proposed new rules on clinical laboratories and protect patients' access to state-of-the art, quality LDTs.

Age-related changes in functional postsynaptic nicotinic acetylcholine receptor subunits in neurons of the laterodorsal tegmental nucleus, a nucleus important in drug addiction

The earlier an individual initiates cigarette smoking, the higher the likelihood of development of dependency to nicotine, the addictive ingredient in cigarettes. One possible mechanism underlying this higher addiction liability is an ontogenetically differential cellular response induced by nicotine in neurons mediating the reinforcing or euphoric effects of this drug, which could arise from age-related differences in the composition of nicotinic acetylcholine receptor (nAChR) subunits. In the current study, we examined whether the subunit composition of nAChRs differed between neurons within the laterodorsal tegmentum (LDT), a nucleus importantly involved in drug addiction associated behaviours, across two periods of ontogeny in which nicotine-mediated excitatory responses were shown to depend on age. To this end, whole-cell patch-clamp recordings in mouse brain slices from identified LDT neurons, in combination with nAChR subunit-specific receptor antagonists, were conducted. Comparison of the contribution of different nAChR subunits to acetylcholine (ACh)-induced inward currents indicated that the contributions of the β2 and/or β4 and α7 nAChR subunits alter across age. Taken together, we conclude that across a limited ontogenetic period, there is plasticity in the subunit composition of nAChRs in LDT neurons. In addition, our data indicate, for the first time, functional presence of α6 nAChR subunits in LDT neurons within the age ranges studied. Changes in subunit composition of nAChRs across ontogeny could contribute to the age-related differential excitability induced by nicotine. Differences in the subunit composition of nAChRs within the LDT would be expected to contribute to ontogenetic-dependent outflow from the LDT to target regions, which include reward-related circuitry.

Endocannabinoid CB1 receptor-mediated rises in Ca(2+) and depolarization-induced suppression of inhibition within the laterodorsal tegmental nucleus

Cannabinoid type 1 receptors (CB1Rs) are functionally active within the laterodorsal tegmental nucleus (LDT), which is critically involved in control of rapid eye movement sleep, cortical arousal, and motivated states. To further characterize the cellular consequences of activation of CB1Rs in this nucleus, we examined whether CB1R activation led to rises in intracellular Ca(2+) ([Ca(2+)]i) and whether processes shown in other regions to involve endocannabinoid (eCB) transmission were present in the LDT. Using a combination of Ca(2+) imaging in multiple cells loaded with Ca(2+) imaging dye via 'bulk-loading' or in single cells loaded with dye via a patch-clamp electrode, we found that WIN 55212-2 (WIN-2), a potent CB1R agonist, induced increases in [Ca(2+)]i which were sensitive to AM251, a CB1R antagonist. A proportion of rises persisted in TTX and/or low-extracellular Ca(2+) conditions. Attenuation of these increases by a reversible inhibitor of sarcoplasmic reticulum Ca(2+)-ATPases, suggests these rises occurred following release of Ca(2+) from intracellular stores. Under voltage clamp conditions, brief, direct depolarization of LDT neurons resulted in a decrease in the frequency and amplitude of AM251-sensitive, inhibitory postsynaptic currents (IPSCs), which was an action sensitive to presence of a Ca(2+) chelator. Finally, actions of DHPG, a mGlu1R agonist, on IPSC activity were examined and found to result in an AM251- and BAPTA-sensitive inhibition of both the frequency and amplitude of sIPSCs. Taken together, our data further characterize CB1R and eCB actions in the LDT and indicate that eCB transmission could play a role in the processes governed by this nucleus.

Nicotine during pregnancy: changes induced in neurotransmission, which could heighten proclivity to addict and induce maladaptive control of attention

Prenatal exposure to nicotine, occurring either via maternal smoking or via use of transdermal nicotine patches to facilitate cigarette abstinence by pregnant women, is associated with ∼ 13% of pregnancies worldwide. Nicotine exposure during gestation has been correlated with several negative physiological and psychosocial outcomes, including heightened risk for aberrant behaviors involving alterations in processing of attention as well as an enhanced liability for development of drug dependency. Nicotine is a terotogen, altering neuronal development of various neurotransmitter systems, and it is likely these alterations participate in postnatal deficits in attention control and facilitate development of drug addiction. This review discusses the alterations in neuronal development within the brain's major neurotransmitter systems, with special emphasis placed on alterations within the laterodorsal tegmental nucleus, in light of the role this cholinergic nucleus plays in attention and addiction. Changes induced within this nucleus by gestational exposure to nicotine, in combination with changes induced in other brain regions, are likely to contribute to the transgenerational burden imposed by nicotine. Although neuroplastic changes induced by nicotine are not likely to act in isolation, and are expected to interact with epigenetic changes induced by preconception exposure to drugs of abuse, unraveling these changes within the developing brain will facilitate eventual development of targeted treatments for the unique vulnerability for arousal disorders and development of addiction within the population of individuals who have been prenatally exposed to nicotine.

Electrophysiological changes in laterodorsal tegmental neurons associated with prenatal nicotine exposure: implications for heightened susceptibility to addict to drugs of abuse

Prenatal nicotine exposure (PNE) is a risk factor for developing an addiction to nicotine at a later stage in life. Understanding the neurobiological changes in reward related circuitry induced by exposure to nicotine prenatally is vital if we are to combat the heightened addiction liability in these vulnerable individuals. The laterodorsal tegmental nucleus (LDT), which is comprised of cholinergic, GABAergic and glutamatergic neurons, is importantly involved in reward mediation via demonstrated excitatory projections to dopamine-containing ventral tegmental neurons. PNE could lead to alterations in LDT neurons that would be expected to alter responses to later-life nicotine exposure. To examine this issue, we monitored nicotine-induced responses of LDT neurons in brain slices of PNE and drug naive mice using calcium imaging and whole-cell patch clamping. Nicotine was found to induce rises in calcium in a smaller proportion of LDT cells in PNE mice aged 7-15 days and smaller rises in calcium in PNE animals from postnatal ages 11-21 days when compared with age-matched control animals. While inward currents induced by nicotine were not found to be different, nicotine did induce larger amplitude excitatory postsynaptic currents in PNE animals in the oldest age group when compared with amplitudes induced in similar-aged control animals. Immunohistochemically identified cholinergic LDT cells from PNE animals exhibited slower spike rise and decay slopes, which likely contributed to the wider action potential observed. Further, PNE was associated with a more negative action potential afterhyperpolarization in cholinergic cells. Interestingly, the changes found in these parameters in animals exposed prenatally to nicotine were age related, in that they were not apparent in animals from the oldest age group examined. Taken together, our data suggest that PNE induces changes in cholinergic LDT cells that would be expected to alter cellular excitability. As the changes are age related, these PNE-associated alterations could contribute differentially across ontogeny to nicotine-mediated reward and may contribute to the particular susceptibility of in utero nicotine exposed individuals to addict to nicotine upon nicotine exposure in the juvenile period.

Age-related changes in nicotine response of cholinergic and non-cholinergic laterodorsal tegmental neurons: implications for the heightened adolescent susceptibility to nicotine addiction

The younger an individual starts smoking, the greater the likelihood that addiction to nicotine will develop, suggesting that neurobiological responses vary across age to the addictive component of cigarettes. Cholinergic neurons of the laterodorsal tegmental nucleus (LDT) are importantly involved in the development of addiction, however, the effects of nicotine on LDT neuronal excitability across ontogeny are unknown. Nicotinic effects on LDT cells across different age groups were examined using calcium imaging and whole-cell patch clamping. Within the youngest age group (P7-P15), nicotine induced larger intracellular calcium transients and inward currents. Nicotine induced a greater number of excitatory synaptic currents in the youngest animals, whereas larger amplitude inhibitory synaptic events were induced in cells from the oldest animals (P15-P34). Nicotine increased neuronal firing of cholinergic cells to a greater degree in younger animals, possibly linked to development associated differences found in nicotinic effects on action potential shape and afterhyperpolarization. We conclude that in addition to age-associated alterations of several properties expected to affect resting cell excitability, parameters affecting cell excitability are altered by nicotine differentially across ontogeny. Taken together, our data suggest that nicotine induces a larger excitatory response in cholinergic LDT neurons from the youngest animals, which could result in a greater excitatory output from these cells to target regions involved in development of addiction. Such output would be expected to be promotive of addiction; therefore, ontogenetic differences in nicotine-mediated increases in the excitability of the LDT could contribute to the differential susceptibility to nicotine addiction seen across age.

Systemic administration and local microinjection into the central nervous system of the 5-HT(7) receptor agonist LP-211 modify the sleep-wake cycle in the rat

The effects of LP-211, a selective serotonin 5-HT7 receptor agonist were studied in adult rats implanted for chronic sleep recordings. Intraperitoneal administration of LP-211 (2.5-10mg/kg) during the light phase of the light-dark cycle significantly increased wakefulness (W) and reduced rapid-eye-movement sleep (REMS) and the number of REM periods during the 6-h recording period. Direct infusion of LP-211 into the dorsal raphe nucleus (DRN) (2-6 mM), locus coeruleus nucleus (LC) (4 mM), basal forebrain (horizontal limb of the diagonal band of Broca) (HDB) (2 mM) or laterodorsal tegmental nucleus (LDT) (4 mM) induced also a decrease of REMS. Additionally, microinjection of the 5-HT7 receptor ligand into the HDB (2 mM) augmented W. Presently, there is no satisfactory explanation for the effect of 5-HT7 receptor activation on W and REMS occurrence. Additional studies are required to characterize the neurotransmitter systems responsible for the actions of LP-211 on the behavioral states.

The cholinergic agonist carbachol increases the frequency of spontaneous GABAergic synaptic currents in dorsal raphe serotonergic neurons in the mouse

Dorsal raphe nucleus (DRN) serotonin (5-HT) neurons play an important role in feeding, mood control and stress responses. One important feature of their activity across the sleep-wake cycle is their reduced firing during rapid-eye-movement (REM) sleep which stands in stark contrast to the wake/REM-on discharge pattern of brainstem cholinergic neurons. A prominent model of REM sleep control posits a reciprocal interaction between these cell groups. 5-HT inhibits cholinergic neurons, and activation of nicotinic receptors can excite DRN 5-HT neurons but the cholinergic effect on inhibitory inputs is incompletely understood. Here, in vitro, in DRN brain slices prepared from GAD67-GFP knock-in mice, a brief (3 min) bath application of carbachol (50 μM) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in GFP-negative, putative 5-HT neurons but did not affect miniature (tetrodotoxin-insensitive) IPSCs. Carbachol had no direct postsynaptic effect. Thus, carbachol likely increases the activity of local GABAergic neurons which synapse on 5-HT neurons. Removal of dorsal regions of the slice including the ventrolateral periaqueductal gray (vlPAG) region where GABAergic neurons projecting to the DRN have been identified, abolished the effect of carbachol on sIPSCs whereas the removal of ventral regions containing the oral region of the pontine reticular nucleus (PnO) did not. In addition, carbachol directly excited GFP-positive, GABAergic vlPAG neurons. Antagonism of both muscarinic and nicotinic receptors completely abolished the effects of carbachol. We suggest cholinergic neurons inhibit DRN 5-HT neurons when acetylcholine levels are lower i.e. during quiet wakefulness and the beginning of REM sleep periods, in part via excitation of muscarinic and nicotinic receptors located on local vlPAG and DRN GABAergic neurons. Higher firing rates or burst firing of cholinergic neurons associated with attentive wakefulness or phasic REM sleep periods leads to excitation of 5-HT neurons via the activation of nicotinic receptors located postsynaptically and presynaptically on excitatory afferents.

Dopaminergic D2 receptor is a key player in the substantia nigra pars compacta neuronal activation mediated by REM sleep deprivation

Currently, several studies addresses the novel link between sleep and dopaminergic neurotransmission, focusing most closely on the mechanisms by which Parkinson's disease (PD) and sleep may be intertwined. Therefore, variations in the activity of afferents during the sleep cycles, either at the level of DA cell bodies in the ventral tegmental area (VTA) and/or substantia nigra pars compacta (SNpc) or at the level of dopamine (DA) terminals in limbic areas may impact functions such as memory. Accordingly, we performed striatal and hippocampal neurochemical quantifications of DA, serotonin (5-HT) and metabolites of rats intraperitoneally treated with haloperidol (1.5 mg/kg) or piribedil (8 mg/kg) and submitted to REM sleep deprivation (REMSD) and sleep rebound (REB). Also, we evaluated the effects of REMSD on motor and cognitive parameters and SNpc c-Fos neuronal immunoreactivity. The results indicated that DA release was strongly enhanced by piribedil in the REMSD group. In opposite, haloperidol prevented that alteration. A c-Fos activation characteristic of REMSD was affected in a synergic manner by piribedil, indicating a strong positive correlation between striatal DA levels and nigral c-Fos activation. Hence, we suggest that memory process is severely impacted by both D2 blockade and REMSD and was even more by its combination. Conversely, the activation of D2 receptor counteracted such memory impairment. Therefore, the present evidence reinforce that the D2 receptor is a key player in the SNpc neuronal activation mediated by REMSD, as a consequence these changes may have direct impact for cognitive and sleep abnormalities found in patients with PD. This article is part of the Special Issue entitled 'The Synaptic Basis of Neurodegenerative Disorders'.

Ventral tegmental ionotropic glutamate receptor stimulation of nucleus accumbens tonic dopamine efflux blunts hindbrain-evoked phasic neurotransmission: implications for dopamine dysregulation disorders

Activation of glutamate receptors within the ventral tegmental area (VTA) stimulates extrasynaptic (basal) dopamine release in terminal regions, including the nucleus accumbens (NAc). Hindbrain inputs from the laterodorsal tegmental nucleus (LDT) are critical for elicitation of phasic VTA dopamine cell activity and consequent transient dopamine release. This study investigated the role of VTA ionotropic glutamate receptor (iGluR) stimulation on both basal and LDT electrical stimulation-evoked dopamine efflux in the NAc using in vivo chronoamperometry and fixed potential amperometry in combination with stearate-graphite paste and carbon fiber electrodes, respectively. Intra-VTA infusion of the iGluR agonists (±)-α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA; 1 μg/μl) or N-methyl-d-aspartic acid (NMDA; 2 μg/μl) enhanced basal NAc dopamine efflux. This iGluR-mediated potentiation of basal dopamine efflux was paralleled by an attenuation of LDT-evoked transient NAc dopamine efflux, suggesting that excitation of basal activity effectively inhibited the capacity of hindbrain afferents to elicit transient dopamine efflux. In line with this, post-NMDA infusion of the dopamine D2 autoreceptor (D2R) agonist quinpirole (1 μg/μl; intra-VTA) partially recovered NMDA-mediated attenuation of LDT-evoked NAc dopamine, while concurrently attenuating NMDA-mediated potentiation of basal dopamine efflux. Post-NMDA infusion of quinpirole (1 μg/μl) alone attenuated basal and LDT-evoked dopamine efflux. Taken together, these data reveal that hyperstimulation of basal dopamine transmission can stunt hindbrain burst-like stimulation-evoked dopamine efflux. Inhibitory autoreceptor mechanisms within the VTA help to partially recover the magnitude of phasic dopamine efflux, highlighting the importance of both iGluRs and D2 autoreceptors in maintaining the functional balance of tonic and phasic dopamine neurotransmission. Dysregulation of this balance may have important implications for disorders of dopamine dysregulation such as attention deficit hyperactivity disorder.

GABA(A) receptors implicated in REM sleep control express a benzodiazepine binding site

It has been reported that non-subtype-selective GABAA receptor antagonists injected into the nucleus pontis oralis (PnO) of rats induced long-lasting increases in REM sleep. Characteristics of these REM sleep increases were identical to those resulting from injection of muscarinic cholinergic agonists. Both actions were blocked by the muscarinic antagonist, atropine. Microdialysis of GABAA receptor antagonists into the PnO resulted in increased acetylcholine levels. These findings were consistent with GABAA receptor antagonists disinhibiting acetylcholine release in the PnO to result in an acetylcholine-mediated REM sleep induction. Direct evidence has been lacking for localization in the PnO of the specific GABAA receptor-subtypes mediating the REM sleep effects. Here, we demonstrated a dose-related, long-lasting increase in REM sleep following injection (60 nl) in the PnO of the inverse benzodiazepine agonist, methyl-6,7-dimethoxy-4-ethyl-β-carboline (DMCM, 10(-2)M). REM sleep increases were greater and more consistently produced than with the non-selective antagonist gabazine, and both were blocked by atropine. Fluorescence immunohistochemistry and laser scanning confocal microscopy, colocalized in PnO vesicular acetylcholine transporter, a presynaptic marker of cholinergic boutons, with the γ2 subunit of the GABAA receptor. These data provide support for the direct action of GABA on mechanisms of acetylcholine release in the PnO. The presence of the γ2 subunit at this locus and the REM sleep induction by DMCM are consistent with binding of benzodiazepines by a GABAA receptor-subtype in control of REM sleep.

Optogenetic strategies to investigate neural circuitry engaged by stress

Optogenetic techniques have given researchers unprecedented access to the function of discrete neural circuit elements and have been instrumental in the identification of novel brain pathways that become dysregulated in neuropsychiatric diseases. For example, stress is integrally linked to the manifestation and pathophysiology of neuropsychiatric illness, including anxiety, addiction and depression. Due to the heterogeneous populations of genetically and neurochemically distinct neurons in areas such as the bed nucleus of the stria terminalis (BNST), as well as their substantial number of projections, our understanding of how neural circuits become disturbed after stress has been limited. Using optogenetic tools, we are now able to selectively isolate distinct neural circuits that contribute to these disorders and perturb these circuits in vivo, which in turn may lead to the normalization of maladaptive behavior. This review will focus on current optogenetic strategies to identify, manipulate, and record from discrete neural circuit elements in vivo as well as highlight recent optogenetic studies that have been utilized to parcel out BNST function.

Reward and aversion in a heterogeneous midbrain dopamine system

The ventral tegmental area (VTA) is a heterogeneous brain structure that serves a central role in motivation and reward processing. Abnormalities in the function of VTA dopamine (DA) neurons and the targets they influence are implicated in several prominent neuropsychiatric disorders including addiction and depression. Recent studies suggest that the midbrain DA system is composed of anatomically and functionally heterogeneous DA subpopulations with different axonal projections. These findings may explain a number of previously confusing observations that suggested a role for DA in processing both rewarding as well as aversive events. Here we will focus on recent advances in understanding the neural circuits mediating reward and aversion in the VTA and how stress as well as drugs of abuse, in particular cocaine, alter circuit function within a heterogeneous midbrain DA system. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Limitations of widely used high-risk human papillomavirus laboratory-developed testing in cervical cancer screening

OBJECTIVE

To increase awareness of the limitations of high-risk human papillomavirus (hrHPV) laboratory-developed testing (LDT) widely used in US cervical cancer screening.

METHODS AND RESULTS

A young woman in her 30s was diagnosed and treated for stage 1B1 cervical squamous cell carcinoma in which HPV 16 DNA was detected using polymerase chain reaction testing. Both 1 month before and 42 months before cervical cancer diagnosis, the patient had highly abnormal cytology findings; however, residual SurePath™ (Becton, Dickson and Company, Franklin Lakes, NJ) vial fluid yielded negative Hybrid Capture 2 (HC2; Qiagen NV, Hilden, Germany) hrHPV LDT results from each of the two specimens. This prompted questions to be asked concerning the performance characteristics of hrHPV LDT. A review of the available data indicates that (1) purification of DNA from SurePath specimens requires complex sample preparation due to formaldehyde crosslinking of proteins and nucleic acids, (2) HC2-SurePath hrHPV testing had not been Food and Drug Administration-approved after multiple premarket approval submissions, (3) detectible hrHPV DNA in the SurePath vial decreases over time, and (4) US laboratories performing HC2-SurePath hrHPV LDT testing are not using a standardized manufacturer-endorsed procedure.

CONCLUSION

Recently updated cervical screening guidelines in the US recommend against the use of hrHPV LDT in cervical screening, including widely used HC2 testing from the SurePath vial. The manufacturer recently issued a technical bulletin specifically warning that use of SurePath samples with the HC2 hrHPV test may provide false negative results and potentially compromise patient safety. Co-collection using a Food and Drug Administration-approved hrHPV test medium is recommended for HPV testing of patients undergoing cervical screening using SurePath samples.

Modernizing US regulatory and reimbursement policy to support continued innovation in genomic pathology

The pace of technical and scientific advancement for genomics-based technologies has outstripped the ability of the US regulatory bodies to keep abreast of the emerging paradigms, resulting in regulatory pronouncements that often appear dated and payment systems that are misaligned. Over burdensome evidentiary requirements, encroachment of federal regulators into the practice of laboratory medicine, and failure to align public health objectives with pay or valuation sufficient to support professional pathology services and necessary capital investment threaten to stifle continued innovation in genomic-based diagnostic tools. Nevertheless, the US FDA is committed to improving regulatory science and to increased stakeholder participation in policy-making, and serious efforts to address coding and test value are underway. Moreover, federal legislation will be debated in the coming months that, if enacted, could clarify authorities and institute meaningful regulatory and reimbursement paradigms better suited to molecular testing. This review explores these dynamic policy issues and their implications for genomic pathology as the foundation of personalized medicine.