Aberrant fast spiking interneuronal activity precedes seizure transitions in humans.

There is active debate regarding how GABAergic function changes during seizure initiation and propagation, and whether interneuronal activity drives or impedes the pathophysiology. Here, we track cell-type specific firing during spontaneous human seizures to identify neocortical mechanisms of inhibitory failure. Fast-spiking interneuron activity was maximal over 1 second before equivalent excitatory increases, and showed transitions to out-of-phase firing prior to local tissue becoming incorporated into the seizure-driving territory. Using computational modeling, we linked this observation to transient saturation block as a precursor to seizure invasion, as supported by multiple lines of evidence in the patient data. We propose that transient blocking of inhibitory firing due to selective fast-spiking interneuron saturation-resulting from intense excitatory synaptic drive-is a novel mechanism that contributes to inhibitory failure, allowing seizure propagation.

The effect of NK3-Saporin injection within the arcuate nucleus on puberty, the LH surge, and the response to Senktide in female sheep†.

The timing of puberty onset is reliant on increased gonadotropin-releasing hormone (GnRH). This elicits a corresponding increase in luteinizing hormone (LH) due to a lessening of sensitivity to the inhibitory actions of estradiol (E2). The mechanisms underlying the increase in GnRH release likely involve a subset of neurons within the arcuate (ARC) nucleus of the hypothalamus that contain kisspeptin, neurokinin B (NKB), and dynorphin (KNDy neurons). We aimed to determine if KNDy neurons in female sheep are critical for: timely puberty onset; the LH surge; and the response to an intravenous injection of the neurokinin-3 receptor (NK3R) agonist, senktide. Prepubertal ewes received injections aimed at the ARC containing blank-saporin (control, n = 5) or NK3-saporin (NK3-SAP, n = 6) to ablate neurons expressing NK3R. Blood samples taken 3/week for 65 days following surgery were assessed for progesterone to determine onset of puberty. Control ewes exhibited onset of puberty at 33.2 ± 3.9 days post sampling initiation, whereas 5/6 NK3-SAP treated ewes didn't display an increase in progesterone. After an artificial LH surge protocol, surge amplitude was lower in NK3-SAP ewes. Finally, ewes were treated with senktide to determine if an LH response was elicited. LH pulses were evident in both groups in the absence of injections, but the response to senktide vs saline was similar between groups. These results show that KNDy cells are necessary for timely puberty onset and for full expresson of the LH surge. The occurrence of LH pulses in NK3-SAP treated ewes may indicate a recovery from an apulsatile state.

Lesions of KNDy and Kiss1R Neurons in the Arcuate Nucleus Produce Different Effects on LH Pulse Patterns in Female Sheep.

The current model for the synchronization of GnRH neural activity driving GnRH and LH pulses proposes that a set of arcuate (ARC) neurons that contain kisspeptin, neurokinin B, and dynorphin (KNDy neurons) is the GnRH pulse generator. This study tested the functional role of ovine KNDy neurons in pulse generation and explored the roles of nearby Kiss1 receptor (Kiss1R)-containing cells using lesions produced with saporin (SAP) conjugates. Injection of NK3-SAP ablated over 90% of the KNDy cells, while Kiss-SAP (saporin conjugated to kisspeptin-54) lesioned about two-thirds of the Kiss1R population without affecting KNDy or GnRH cell number. Both lesions produced a dramatic decrease in LH pulse amplitude but had different effects on LH pulse patterns. NK3-SAP increased interpulse interval, but Kiss-SAP did not. In contrast, Kiss-SAP disrupted the regular hourly occurrence of LH pulses, but NK3-SAP did not. Because Kiss1R is not expressed in KNDy cells, HiPlex RNAScope was used to assess the colocalization of 8 neurotransmitters and 3 receptors in ARC Kiss1R-containing cells. Kiss1R cells primarily contained transcript markers for GABA (68%), glutamate (28%), ESR1 (estrogen receptor-α) mRNA, and OPRK1 (kappa opioid receptor) mRNA. These data support the conclusion that KNDy neurons are essential for GnRH pulses in ewes, whereas ARC Kiss1R cells are not but do maintain the amplitude and regularity of GnRH pulses. We thus propose that in sheep, ARC Kiss1R neurons form part of a positive feedback circuit that reinforces the activity of the KNDy neural network, with GABA or glutamate likely being involved.

KNDy neurons as the GnRH pulse generator: Recent studies in ruminants.

This review considers three aspects of recent work on the role of KNDy neurons in GnRH pulse generation in ruminants. First, work on basic mechanisms of pulse generation includes several tests of this hypothesis, all of which support it, and evidence that Kiss1r-containing neurons form a positive feedback circuit with the KNDy neural network that strengthen the activity of this network. The second section on pathways mediating external inputs focuses on the influence of nutrition and photoperiod, and describes the evidence supporting roles for proopiomelanocortin (POMC) and agouti-related peptide (AgRP) afferents to KNDy cells in each of these. Finally, we review studies exploring the potential applications of manipulating signaling by kisspeptin, and the other KNDy peptides, to control reproductive function in domestic animals and conclude that, although these approaches show some promise, they do not have major advantages over current practices at this time.

Spatiotemporal spike-centered averaging reveals symmetry of temporal and spatial components of the spike-LFP relationship during human focal seizures.

The electrographic manifestation of neural activity can reflect the relationship between the faster action potentials of individual neurons and the slower fluctuations of the local field potential (LFP). This relationship is typically examined in the temporal domain using the spike-triggered average. In this study, we add a spatial component to this relationship. Here we first derive a theoretical model of the spike-LFP relationship across a macroelectrode. This mathematical derivation showed a special symmetry in the spike-LFP relationship wherein a sinc function in the temporal domain predicts a sinc function in the spatial domain. We show that this theoretical result is observed in a real-world system by characterizing the spike-LFP relationship using microelectrode array (MEA) recordings of human focal seizures. To do this, we present a approach, termed the spatiotemporal spike-centered average (st-SCA), that allows for visualization of the spike-LFP relationship in both the temporal and spatial domains. We applied this method to 25 MEA recordings obtained from seven patients with pharmacoresistant focal epilepsy. Of the five patients with MEAs implanted in recruited territory, three exhibited spatiotemporal patterns consistent with a sinc function, and two exhibited spatiotemporal patterns resembling deep wells of excitation. These results suggest that in some cases characterization of the spike-LFP relationship in the temporal domain is sufficient to predict the underlying spatial pattern. Finally, we discuss the biological interpretation of these findings and propose that the sinc function may reflect the role of mid-range excitatory connections during seizure activity.

Calcifying Pseudoneoplasm of the Neuraxis in the Posterior Fossa: A Case Report and Literature Review.

Calcifying pseudoneoplasm of the neuraxis are rare fibro-osseous lesions that can occur throughout the central nervous system. This paper reports one case of this lesion within the posterior fossa and contains a literature review of all cases documented within the posterior fossa to date. A 53-year-old female patient with a history of epiphora, facial irritation, and headaches was found to have a mass centered in the posterior fossa. The patient underwent surgical resection for removal of the mass. Upon review by pathology, the final diagnosis was consistent with calcifying pseudoneoplasm of the neuraxis.

Neuroendocrine control of gonadotropin-releasing hormone: Pulsatile and surge modes of secretion.

The concept that different systems control episodic and surge secretion of gonadotropin-releasing hormone (GnRH) was well established by the time that GnRH was identified and formed the framework for studies of the physiological roles of GnRH, and later kisspeptin. Here, we focus on recent studies identifying the neural mechanisms underlying these two modes of secretion, with an emphasis on their core components. There is now compelling data that kisspeptin neurons in the arcuate nucleus that also contain neurokinin B (NKB) and dynorphin (i.e., KNDy cells) and their projections to GnRH dendrons constitute the GnRH pulse generator in mice and rats. There is also strong evidence for a similar role for KNDy neurons in sheep and goats, and weaker data in monkeys and humans. However, whether KNDy neurons act on GnRH dendrons and/or GnRH soma and dendrites that are found in the mediobasal hypothalamus (MBH) of these species remains unclear. The core components of the GnRH/luteinising hormone surge consist of an endocrine signal that initiates the process and a neural trigger that drives GnRH secretion during the surge. In all spontaneous ovulators, the core endocrine signal is a rise in estradiol secretion from the maturing follicle(s), with the site of estrogen positive feedback being the rostral periventricular kisspeptin neurons in rodents and neurons in the MBH of sheep and primates. There is considerable species variations in the neural trigger, with three major classes. First, in reflex ovulators, this trigger is initiated by coitus and carried to the hypothalamus by neural or vascular pathways. Second, in rodents, there is a time of day signal that originates in the suprachiasmatic nucleus and activates rostral periventricular kisspeptin neurons and GnRH soma and dendrites. Finally, in sheep nitric oxide-producing neurons in the ventromedial nucleus, KNDy neurons and rostral kisspeptin neurons all appear to participate in driving GnRH release during the surge.

Human interictal epileptiform discharges are bidirectional traveling waves echoing ictal discharges.

Interictal epileptiform discharges (IEDs), also known as interictal spikes, are large intermittent electrophysiological events observed between seizures in patients with epilepsy. Although they occur far more often than seizures, IEDs are less studied, and their relationship to seizures remains unclear. To better understand this relationship, we examined multi-day recordings of microelectrode arrays implanted in human epilepsy patients, allowing us to precisely observe the spatiotemporal propagation of IEDs, spontaneous seizures, and how they relate. These recordings showed that the majority of IEDs are traveling waves, traversing the same path as ictal discharges during seizures, and with a fixed direction relative to seizure propagation. Moreover, the majority of IEDs, like ictal discharges, were bidirectional, with one predominant and a second, less frequent antipodal direction. These results reveal a fundamental spatiotemporal similarity between IEDs and ictal discharges. These results also imply that most IEDs arise in brain tissue outside the site of seizure onset and propagate toward it, indicating that the propagation of IEDs provides useful information for localizing the seizure focus.

Corpus Callosotomy in the Modern Era: Origins, Efficacy, Technical Variations, Complications, and Indications.

Corpus callosotomy is among the oldest surgeries performed for drug-resistant epilepsy. Since it was first performed in 1940, numerous studies have assessed its outcomes in various patient populations in addition to describing different extents of sectioning and emerging technologies (i.e., endoscopic, laser interstitial thermal therapy, and radiosurgery). To capture the current state and offer a reappraisal, we comprehensively review the origins of corpus callosotomy, efficacy for various seizure types, technical variations, complications, and indications and compare the procedure with vagus nerve stimulation therapy, which has similar indications. We consider corpus callosotomy to be a safe and efficacious procedure, which should be considered by clinicians when appropriate. Furthermore, it can play an important role in treating patients with drug-resistant epilepsy when appropriate in low-to-middle-income countries where resources are limited.

Evidence that synaptic plasticity of glutamatergic inputs onto KNDy neurones during the ovine follicular phase is dependent on increasing levels of oestradiol.

Neurones in the arcuate nucleus co-expressing kisspeptin, neurokinin B (NKB) and dynorphin (KNDy) play a critical role in the control of gonadotrophin-releasing hormone (GnRH) and luteinising hormone (LH) secretion. In sheep, KNDy neurones mediate both steroid-negative- and -positive-feedback during pulsatile and preovulatory surge secretions of GnRH/LH, respectively. In addition, KNDy neurones receive glutamatergic inputs expressing vGlut2, a glutamate transporter that serves as a marker for those terminals, from both KNDy neurones and other populations of glutamatergic neurones. Previous work reported higher numbers of vGlut2-positive axonal inputs onto KNDy neurones during the LH surge than in luteal phase ewes. In the present study, we further examined the effects of the ovarian steroids progesterone (P) and oestradiol (E2 ) on glutamatergic inputs to KNDy neurones. Ovariectomised (OVX) ewes received either no further treatment (OVX) or steroid treatments that mimicked the luteal phase (low E2  + P), and early (low E2 ) or late follicular (high E2 ) phases of the oestrous cycle (n = 4 or 5 per group). Brain sections were processed for triple-label immunofluorescent detection of NKB/vGlut2/synaptophysin and analysed using confocal microscopy. We found higher numbers of vGlut2 inputs onto KNDy neurones in high E2 compared to the other three treatment groups. These results suggest that synaptic plasticity of glutamatergic inputs onto KNDy neurones during the ovine follicular phase depend on increasing levels of E2 required for the preovulatory GnRH/surge. These synaptic changes likely contribute to the positive-feedback action of oestrogen on GnRH/LH secretion and thus the generation of the preovulatory surge in the sheep.

Progesterone in Addition to Standard of Care vs Standard of Care Alone in the Treatment of Men Hospitalized With Moderate to Severe COVID-19: A Randomized, Controlled Pilot Trial.

BACKGROUND: Severity of illness in COVID-19 is consistently lower in women. A focus on sex as a biological factor may suggest a potential therapeutic intervention for this disease. We assessed whether adding progesterone to standard of care (SOC) would improve clinical outcomes of hospitalized men with moderate to severe COVID-19. RESEARCH QUESTION: Does short-term subcutaneous administration of progesterone safely improve clinical outcome in hypoxemic men hospitalized with COVID-19? STUDY DESIGN AND METHODS: We conducted a pilot, randomized, open-label, controlled trial of subcutaneous progesterone in men hospitalized with confirmed moderate to severe COVID-19. Patients were randomly assigned to receive SOC plus progesterone (100 mg subcutaneously twice daily for up to 5 days) or SOC alone. In addition to assessment of safety, the primary outcome was change in clinical status on day 7. Length of hospital stay and number of days on supplemental oxygen were key secondary outcomes. RESULTS: Forty-two patients were enrolled from April 2020 to August 2020; 22 were randomized to the control group and 20 to the progesterone group. Two patients from the progesterone group withdrew from the study before receiving progesterone. There was a 1.5-point overall improvement in median clinical status score on a seven-point ordinal scale from baseline to day 7 in patients in the progesterone group as compared with control subjects (95% CI, 0.0-2.0; P = .024). There were no serious adverse events attributable to progesterone. Patients treated with progesterone required three fewer days of supplemental oxygen (median, 4.5 vs 7.5 days) and were hospitalized for 2.5 fewer days (median, 7.0 vs 9.5 days) as compared with control subjects. INTERPRETATION: Progesterone at a dose of 100 mg, twice daily by subcutaneous injection in addition to SOC, may represent a safe and effective approach for treatment in hypoxemic men with moderate to severe COVID-19. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT04365127; URL: www.clinicaltrials.gov.

Psychiatric comorbidity is common in dystonia and other movement disorders.

OBJECTIVE: To determine rates of psychiatric comorbidity in a clinical sample of childhood movement disorders (MDs). DESIGN: Cohort study. SETTING: Tertiary children's hospital MD clinics in Sydney, Australia and London, UK. PATIENTS: Cases were children with tic MDs (n=158) and non-tic MDs (n=102), including 66 children with dystonia. Comparison was made with emergency department controls (n=100), neurology controls with peripheral neuropathy or epilepsy (n=37), and community controls (n=10 438). INTERVENTIONS: On-line development and well-being assessment which was additionally clinically rated by experienced child psychiatrists. MAIN OUTCOME MEASURES: Diagnostic schedule and manual of mental disorders-5 criteria for psychiatric diagnoses. RESULTS: Psychiatric comorbidity in the non-tic MD cohort (39.2%) was comparable to the tic cohort (41.8%) (not significant). Psychiatric comorbidity in the non-tic MD cohort was greater than the emergency control group (18%, p<0.0001) and the community cohort (9.5%, p<0.00001), but not the neurology controls (29.7%, p=0.31). Almost half of the patients within the tic cohort with psychiatric comorbidity were receiving medical psychiatric treatment (45.5%) or psychology interventions (43.9%), compared with only 22.5% and 15.0%, respectively, of the non-tic MD cohort with psychiatric comorbidity. CONCLUSIONS: Psychiatric comorbidity is common in non-tic MDs such as dystonia. These psychiatric comorbidities appear to be under-recognised and undertreated.

Neuronal Firing and Waveform Alterations through Ictal Recruitment in Humans.

Analyzing neuronal activity during human seizures is pivotal to understanding mechanisms of seizure onset and propagation. These analyses, however, invariably using extracellular recordings, are greatly hindered by various phenomena that are well established in animal studies: changes in local ionic concentration, changes in ionic conductance, and intense, hypersynchronous firing. The first two alter the action potential waveform, whereas the third increases the "noise"; all three factors confound attempts to detect and classify single neurons. To address these analytical difficulties, we developed a novel template-matching-based spike sorting method, which enabled identification of 1239 single neurons in 27 patients (13 female) with intractable focal epilepsy, that were tracked throughout multiple seizures. These new analyses showed continued neuronal firing with widespread intense activation and stereotyped action potential alterations in tissue that was invaded by the seizure: neurons displayed increased waveform duration (p < 0.001) and reduced amplitude (p < 0.001), consistent with prior animal studies. By contrast, neurons in "penumbral" regions (those receiving intense local synaptic drive from the seizure but without neuronal evidence of local seizure invasion) showed stable waveforms. All neurons returned to their preictal waveforms after seizure termination. We conclude that the distinction between "core" territories invaded by the seizure versus "penumbral" territories is evident at the level of single neurons. Furthermore, the increased waveform duration and decreased waveform amplitude are neuron-intrinsic hallmarks of seizure invasion that impede traditional spike sorting and could be used as defining characteristics of local recruitment.SIGNIFICANCE STATEMENT Animal studies consistently show marked changes in action potential waveform during epileptic discharges, but acquiring similar evidence in humans has proven difficult. Assessing neuronal involvement in ictal events is pivotal to understanding seizure dynamics and in defining clinical localization of epileptic pathology. Using a novel method to track neuronal firing, we analyzed microelectrode array recordings of spontaneously occurring human seizures, and here report two dichotomous activity patterns. In cortex that is recruited to the seizure, neuronal firing rates increase and waveforms become longer in duration and shorter in amplitude as the neurons are recruited to the seizure, while penumbral tissue shows stable action potentials, in keeping with the "dual territory" model of seizure dynamics.

Dual mechanisms of ictal high frequency oscillations in human rhythmic onset seizures.

High frequency oscillations (HFOs) are bursts of neural activity in the range of 80 Hz or higher, recorded from intracranial electrodes during epileptiform discharges. HFOs are a proposed biomarker of epileptic brain tissue and may also be useful for seizure forecasting. Despite such clinical utility of HFOs, the spatial context and neuronal activity underlying these local field potential (LFP) events remains unclear. We sought to further understand the neuronal correlates of ictal high frequency LFPs using multielectrode array recordings in the human neocortex and mesial temporal lobe during rhythmic onset seizures. These multiscale recordings capture single cell, multiunit, and LFP activity from the human brain. We compare features of multiunit firing and high frequency LFP from microelectrodes and macroelectrodes during ictal discharges in both the seizure core and penumbra (spatial seizure domains defined by multiunit activity patterns). We report differences in spectral features, unit-local field potential coupling, and information theoretic characteristics of high frequency LFP before and after local seizure invasion. Furthermore, we tie these time-domain differences to spatial domains of seizures, showing that penumbral discharges are more broadly distributed and less useful for seizure localization. These results describe the neuronal and synaptic correlates of two types of pathological HFOs in humans and have important implications for clinical interpretation of rhythmic onset seizures.

Morphological and functional evidence for sexual dimorphism in neurokinin B signalling in the retrochiasmatic area of sheep.

Neurokinin B (NKB) is critical for fertility in humans and stimulates gonadotrophin-releasing hormone/luteinising hormone (LH) secretion in several species, including sheep. There is increasing evidence that the actions of NKB in the retrochiasmatic area (RCh) contribute to the induction of the preovulatory LH surge in sheep. In the present study, we determined whether there are sex differences in the response to RCh administration of senktide, an agonist to the NKB receptor (neurokinin receptor-3 [NK3R]), and in NKB and NK3R expression in the RCh of sheep. To normalise endogenous hormone concentrations, animals were gonadectomised and given implants to mimic the pattern of ovarian steroids seen in the oestrous cycle. In females, senktide microimplants in the RCh produced an increase in LH concentrations that lasted for at least 8 hours after the start of treatment, whereas a much shorter increment (approximately 2 hours) was seen in males. We next collected tissue from gonadectomised lambs 18 hours after the insertion of oestradiol implants that produce an LH surge in female, but not male, sheep for immunohistochemical analysis of NKB and NK3R expression. As expected, there were more NKB-containing neurones in the arcuate nucleus of females than males. Interestingly, there was a similar sexual dimorphism in NK3R-containing neurones in the RCh, NKB-containing close contacts onto these RCh NK3R neurones, and overall NKB-positive fibres in this region. These data demonstrate that there are both functional and morphological sex differences in NKB-NK3R signalling in the RCh and raise the possibility that this dimorphism contributes to the sex-dependent ability of oestradiol to induce an LH surge in female sheep.

A model for focal seizure onset, propagation, evolution, and progression.

We developed a neural network model that can account for major elements common to human focal seizures. These include the tonic-clonic transition, slow advance of clinical semiology and corresponding seizure territory expansion, widespread EEG synchronization, and slowing of the ictal rhythm as the seizure approaches termination. These were reproduced by incorporating usage-dependent exhaustion of inhibition in an adaptive neural network that receives global feedback inhibition in addition to local recurrent projections. Our model proposes mechanisms that may underline common EEG seizure onset patterns and status epilepticus, and postulates a role for synaptic plasticity in the emergence of epileptic foci. Complex patterns of seizure activity and bi-stable seizure end-points arise when stochastic noise is included. With the rapid advancement of clinical and experimental tools, we believe that this model can provide a roadmap and potentially an in silico testbed for future explorations of seizure mechanisms and clinical therapies.

Evidence that Nitric Oxide Is Critical for LH Surge Generation in Female Sheep.

Elevated and sustained estradiol concentrations cause a gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) surge that is necessary for ovulation. In sheep, several different neural systems have been implicated in this stimulatory action of estradiol and this study focused on somatostatin (SST) neurons in the ventral lateral region of the ventral medial nucleus (vlVMN) which express c-Fos during the surge. First, we determined if increased activity of SST neurons could be related to elevated GnRH secretion by assessing SST synapses onto GnRH neurons and neurons coexpressing kisspeptin, neurokinin B, dynorphin (KNDy). We found that the percentage of preoptic area GnRH neurons that receive SST input increased during the surge compared with other phases of the cycle. However, since SST is generally inhibitory, and pharmacological manipulation of SST signaling did not alter the LH surge in sheep, we hypothesized that nitric oxide (NO) was also produced by these neurons to account for their activation during the surge. In support of this hypothesis we found that (1) the majority of SST cells in the vlVMN (>80%) contained neuronal nitric oxide synthase (nNOS); (2) the expression of c-Fos in dual-labeled SST-nNOS cells, but not in single-labeled cells, increased during the surge compared with other phases of the cycle; and (3) intracerebroventricular (ICV) infusion of the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester, completely blocked the estrogen-induced LH surge. These data support the hypothesis that the population of SST-nNOS cells in the vlVMN are a source of NO that is critical for the LH surge, and we propose that they are an important site of estradiol positive feedback in sheep.

Heavy drinking in adolescents is associated with change in brainstem microstructure and reward sensitivity.

Heavy drinker adolescents: altered brainstem microstructure.

The cortical-cerebellar circuit is vulnerable to heavy drinking (HD) in adults. We hypothesized early microstructural modifications of the pons/midbrain region, containing core structures of the reward system, in HD adolescents. Thirty-two otherwise symptom-free HDs at age 14 (HD14) and 24 abstainers becoming HDs at age 16 (HD16) were identified in the community with the Alcohol Use Disorders Identification Test (AUDIT) and compared with abstainers. The monetary incentive delay (MID) task assessed reward-sensitive performance. Voxelwise statistics of diffusion tensor imaging (DTI) values in the thalamo-ponto-mesencephalic region were obtained using tract-based spatial statistics. Projections between the ventral tegmental area (VTA) and the nucleus accumbens (NAcc) were identified by probabilistic tractography. Lower fraction of anisotropy and higher radial diffusivity (RD) values were detected in the upper dorsal pons of HD14 adolescents, and a trend for higher RD in HD16, compared with abstainers. When expecting reward, HD14 had higher MID task success scores than abstainers, and success scores were higher with a lower number of tracts in all adolescents. In symptom-free community adolescents, a region of lower white matter (WM) integrity in the pons at age 14 was associated with current HD and predicted HD at age 16. HD was related to reward sensitivity.

Does the KNDy Model for the Control of Gonadotropin-Releasing Hormone Pulses Apply to Monkeys and Humans?

There is now considerable evidence supporting the role of a subpopulation of neurons in the arcuate nucleus of the hypothalamus that coexpress kisspeptin, neurokinin B, and dynorphin (abbreviated as KNDy neurons) as the long sought-after gonadotropin-releasing hormone (GnRH) pulse generator. The "KNDy hypothesis" of pulse generation has largely been based on findings in rodents and ruminants, and there is considerably less information about the anatomical and functional organization of the KNDy subpopulation in the primate hypothalamus. In this review, we focus on the applicability of this hypothesis, and the roles of kisspeptin, neurokinin B, and dynorphin in reproduction, to humans and nonhuman primates, reviewing available data and pointing out important gaps in our current knowledge. With recent application of drugs that target KNDy peptides and their receptors to therapeutic treatments for reproductive disorders, it is imperative we fully understand the primate KNDy network and its role in the control of GnRH secretion, as well as species differences in this system that may exist between humans, nonhuman primates, and other mammals.

Billing and payment of commercial and Medicaid health plan adult vaccination claims in Michigan since the Affordable Care Act.

BACKGROUND: Provider concern regarding insurance non-payment for vaccines is a common barrier to provision of adult immunizations. We examined current adult vaccination billing and payment associated with two managed care populations to identify reasons for non-payment of immunization insurance claims. METHODS: We assessed administrative data from 2014 to 2015 from Blue Care Network of Michigan, a nonprofit health maintenance organization, and Blue Cross Complete of Michigan, a Medicaid managed care plan, to determine rates of and reasons for non-payment of adult vaccination claims across patient-care settings, insurance plans, and vaccine types. We compared commercial and Medicaid payment rates to Medicare payment rates and examined patient cost sharing. RESULTS: Pharmacy-submitted claims for adult vaccine doses were almost always paid (commercial 98.5%; Medicaid 100%). As the physician office accounted for the clear majority (79% commercial; 69% Medicaid) of medical (non-pharmacy) vaccination services, we limited further analyses of both commercial and Medicaid medical claims to the physician office setting. In the physician office setting, rates of payment were high with commercial rates of payment (97.9%) greater than Medicaid rates (91.6%). Reasons for non-payment varied, but generally related to the complexity of adult vaccine recommendations (patient diagnosis does not match recommendations) or insurance coverage (complex contracts, multiple insurance payers). Vaccine administration services were also generally paid. Commercial health plan payments were greater for both vaccine dose and vaccine administration than Medicare payments; Medicaid paid a higher amount for the vaccine dose, but less for vaccine administration than Medicare. Patients generally had very low (commercial) or no (Medicaid) cost-sharing for vaccination. CONCLUSIONS: Adult vaccine dose claims were usually paid. Medicaid generally had higher rates of non-payment than commercial insurance.