Spindle oscillations in communicating axons within a reconstituted hippocampal formation are strongest in CA3 without thalamus

Spindle-shaped waves of oscillations emerge in EEG scalp recordings during human and rodent non-REM sleep. The association of these 10-16 Hz oscillations with events during prior wakefulness suggests a role in memory consolidation. Human and rodent depth electrodes in the brain record strong spindles throughout the cortex and hippocampus, with possible origins in the thalamus. However, the source and targets of the spindle oscillations from the hippocampus are unclear. Here, we employed an in vitro reconstruction of four subregions of the hippocampal formation with separate microfluidic tunnels for single axon communication between subregions assembled on top of a microelectrode array. We recorded spontaneous 400-1000 ms long spindle waves at 10-16 Hz in single axons passing between subregions as well as from individual neurons in those subregions. Spindles were nested within slow waves. The highest amplitudes and most frequent occurrence suggest origins in CA3 neurons that send feed-forward axons into CA1 and feedback axons into DG. Spindles had 50-70% slower conduction velocities than spikes and were not phase-locked to spikes suggesting that spindle mechanisms are independent of action potentials. Therefore, consolidation of declarative-cognitive memories in the hippocampus may be separate from the more easily accessible consolidation of memories related to thalamic motor function.

Reduced cerebello-cerebral functional connectivity correlates with disease severity and impaired white matter integrity in Friedreich ataxia

Friedreich ataxia (FRDA) is a rare, inherited neurodegenerative disease characterised in most cases by progressive and debilitating motor dysfunction. Degeneration of cerebellar white matter pathways have been previously reported, alongside indications of cerebello-cerebral functional alterations. In this work, we examine resting-state functional connectivity changes within cerebello-cerebral circuits, and their associations with disease severity (Scale for the Assessment and Rating of Ataxia [SARA]), psychomotor function (speeded and paced finger tapping), and white matter integrity (diffusion tensor imaging) in 35 adults with FRDA and 45 age and sex-matched controls. Voxel-wise seed-based functional connectivity was assessed for three cerebellar cortical regions (anterior lobe, lobules I-V; superior posterior lobe, lobules VI-VIIB; inferior posterior lobe, lobules VIIIA-IX) and two dentate nucleus seeds (dorsal and ventral). Compared to controls, people with FRDA showed significantly reduced connectivity between the anterior cerebellum and bilateral pre/postcentral gyri, and between the superior posterior cerebellum and left dorsolateral PFC. Greater disease severity correlated with lower connectivity in these circuits. Lower anterior cerebellum-motor cortex functional connectivity also correlated with slower speeded finger tapping and less fractional anisotropy in the superior cerebellar peduncles, internal capsule, and precentral white matter in the FRDA cohort. There were no significant between-group differences in inferior posterior cerebellar or dentate nucleus connectivity. This study indicates that altered cerebello-cerebral functional connectivity is associated with functional status and white matter damage in cerebellar efferent pathways in people with FRDA, particularly in motor circuits.

Hippocampal transplants of fetal GABAergic progenitors regulate adult neurogenesis in mice with temporal lobe epilepsy

GABAergic interneurons play a role in regulating adult neurogenesis within the dentate gyrus (DG) of the hippocampus. Neurogenesis occurs within a stem cell niche in the subgranular zone (SGZ) of the DG. In this niche, populations of neural progenitors give rise to granule cells that migrate radially into the granule cell layer of the DG. Altered neurogenesis in temporal lobe epilepsy (TLE) is linked to a transient increase in the proliferation of new neurons and the abnormal inversion of Type 1 progenitors, resulting in ectopic migration of Type 3 progenitors into the hilus of the DG. These ectopic cells mature into granule cells in the hilus that become hyperexcitable and contribute to the development of spontaneous recurrent seizures. To test whether grafts of GABAergic cells in the DG restore synaptic inhibition, prior work focused on transplanting GABAergic progenitors into the hilus of the DG. This cell-based therapeutic approach was shown to alter the disease phenotype by ameliorating spontaneous seizures in mice with pilocarpine-induced TLE. Prior optogenetic and immunohistochemical studies demonstrated that the transplanted GABAergic interneurons increased levels of synaptic inhibition by establishing inhibitory synaptic contacts with adult-born granule cells, consistent with the observed suppression of seizures. Whether GABAergic progenitor transplantation into the DG ameliorates underlying abnormalities in adult neurogenesis caused by TLE is not known. As a first step to address this question, we compared the effects of GABAergic progenitor transplantation on Type 1, Type 2, and Type 3 progenitors in the stem cell niche using cell type-specific molecular markers in naïve, non-epileptic mice. The progenitor transplantation increased GABAergic interneurons in the DG and led to a significant reduction in Type 2 progenitors and a concomitant increase in Type 3 progenitors. Next, we compared the effects of GABAergic interneuron transplantation in epileptic mice. Transplantation of GABAergic progenitors resulted in reductions in inverted Type 1, Type 2, and hilar ectopic Type 3 cells, concomitant with an increase in the radial migration of Type 3 progenitors into the GCL (Granule Cell Layer). Thus, in mice with Pilocarpine induced TLE, hilar transplants of GABA interneurons may reverse abnormal patterns of adult neurogenesis, an outcome that may ameliorate seizures.

Health and quality of life differ between community living older people with and without remaining teeth who recently received formal home care: a cross sectional study

Objective

To assess oral health, health, and quality of life (QoL) of care-dependent community-living older people with and without remaining teeth who recently received formal home care.

Materials and methods

For this cross-sectional observational study, community-living older people (≥ 65 years), who recently (< 6 months) received formal home care, were interviewed with validated questionnaires and underwent an oral examination. Oral health, general health, medicines usage, frailty (Groningen Frailty Indicator), cognition (Minimal Mental State Examination), QoL (RAND 36), and oral health-related QoL (Oral Health Impact Profile-14) were assessed.

Results

One hundred three out of 275 consecutive eligible older people (median age 79 [IQR (Inter Quartile Range) 72–85 years] participated in the study. Thirty-nine patients had remaining teeth and 64 were edentulous. Compared with edentulous older people, older people with remaining teeth scored significantly better on frailty, QoL, physical functioning, and general health. No significant differences were seen in cognition. Dental and periodontal problems were seen in more than half of the patients with remaining teeth. Two third of the edentulous patients did not visit their dentist regularly or at all.

Conclusions

Care-dependent home-dwelling older people with remaining teeth generally were less frail, scored better on physical functioning and general health and had better QoL than edentulous older people. Dental and periodontal problems were seen in approximately 50% of the elderly.

Clinical relevance

Notwithstanding their common dental problems, frailty, health, and QoL are better in home-dwelling older people with remaining teeth. To maintain this status, we advise not only dentists, but also health care workers and governments, to encourage people to maintain good oral health.

Edentulism and transplant-associated complications in patients with multiple myeloma undergoing autologous hematopoietic stem cell transplantation

PURPOSE

Patients undergoing autologous hematopoietic stem cell transplantation (HSCT) are at risk for oral complications which may cause significant morbidity. The aim of this study was to compare the incidence of toxicities and complications in edentulous and dentate patients undergoing autologous HSCT for multiple myeloma.

METHODS

We conducted a retrospective case-control study to analyze the incidence of bacteremia, fever, and oral mucositis, between edentulous and dentate patients. All patients underwent dental evaluation, received dental treatment if indicated, and were cleared before transplantation. The two groups were matched for age, gender, ethnicity, disease stage, time from diagnosis to transplant, performance status, and conditioning regimen.

RESULTS

A total of 45 edentulous and 90 dentate patients were enrolled. All patients were male with a median age of 60 years and a mean performance status by Karnofsky score of 90 %. Two thirds had stage III MM with a median time from diagnosis to transplantation of 12 months, and all received melphalan as part of the conditioning regimen. The incidence of bacteremia (p = 0.553), fever (p = 0.245), severity of oral mucositis (p = 0.465), and other post-transplant toxicities were similar between both groups.

CONCLUSIONS

There were no significant differences in the incidence of bacteremia, fever, severity of oral mucositis, or other complications between edentulous and dentate patients with multiple myeloma after autologous HSCT.

Does the state of dentition effect the type of stylohyoid chain calcification pattern?

INTRODUCTION

The human stylohyoid chain calcification patterns (SCP) present considerable anatomic variability. This study was performed to investigate the calcification on SCP in the dentate and total edentulous population and its relation to mandibular protrusive movement.

MATERIALS AND METHODS

The study analyzed 1.234 SCP in digital panoramic radiographs of 617 subjects. The SCP were classified according to Mac Donald-Jankowski. The amount of mandibular protrusion movement limitation was evaluated for each subject. The data were analyzed using one-way Anova, Kruskall Wallis, Mann-Whitney U, and Chi-squared tests with significance set at p = 0.05.

RESULTS

Among the 617 subjects evaluated there was symmetry of the SCP between the left and right sides in 87.3 % of the cases. In the study population 501 subjects were dentate (Class I, Class II, Class III molar relationship) and 116 subjects were total edentulous. There were significant differences among dentate and total edentulous patients for the distribution of SCP (p < 0.05). Elongated group was more prevalent in total edentulous subjects while in subjects with Class I occlusion normal SCP was observed. Although mandibular protrusive movement range was within normal limits for all the groups, calcified and elongated groups have numerically less protrusive movement compared to normal groups (p < 0.05).

CONCLUSION

Among dentate and total edentulous subjects, similarity in SCP for right and left side was observed. The elongation of SCP was more common in the total edentulous group. Further studies conducted on larger populations are necessary to establish the effect of the state of dentition on the SCP.