Vertical and Leg Stiffness Modeling During Running: Effect of Speed and Incline.

A spring mass model is often used to describe human running, allowing to understand the concept of elastic energy storage and restitution. The stiffness of the spring is a key parameter and different methods have been developed to estimate both the vertical and the leg stiffness components. Nevertheless, the validity and the range of application of these models are still debated. The aim of the present study was to compare three methods (i. e., Temporal, Kinetic and Kinematic-Kinetic) of stiffness determination. Twenty-nine healthy participants equipped with reflective markers performed 5-min running bouts at four running speeds and eight inclines on an instrumented treadmill surrounded by a tri-dimensional motion camera system. The three methods provided valid results among the different speeds, but the reference method (i. e., Kinematic-Kinetic) provided higher vertical stiffness and lower leg stiffness than the two other methods (both p<0.001). On inclined terrain, the method using temporal parameters provided non valid outcomes and should not be used. Finally, this study highlights that both the assumption of symmetry between compression and decompression phases or the estimation of the vertical displacement and changes in leg length are the major sources of errors when comparing different speeds or different slopes.

Inertial Sensor-Based Estimation of Temporal Events in Skating Sub-Techniques While In-Field Roller Skiing.

The aim of this study was to test and adapt a treadmill-developed method for determination of inner-cycle parameters and sub-technique in cross-country roller ski skating for a field application. The method is based on detecting initial and final ground contact of poles and skis during cyclic movements. Eleven athletes skied 4 laps of 2.5 km at low- and high-endurance intensities, using 2 types of skis with different rolling coefficients. Participants were equipped with inertial measurement units attached to their wrists and skis, and insoles with pressure sensors and poles with force measurements were used as reference systems. The method based on inertial measurement units was able to detect >97% of the temporal events detected with the reference system. The inner-cycle temporal parameters had a precision ranging from 49 to 59 milliseconds, corresponding to 3.9% to 13.7% of the corresponding inner-cycle duration. Overall, this study showed good reliability of using inertial measurement units on athletes' wrists and skis to determine temporal events, inner-cycle parameters, and the performed sub-techniques in cross-country roller ski skating in field conditions.

Inner-Cycle Phases Can Be Estimated from a Single Inertial Sensor by Long Short-Term Memory Neural Network in Roller-Ski Skating.

OBJECTIVE: The aim of this study was to provide a new machine learning method to determine temporal events and inner-cycle parameters (e.g., cycle, pole and ski contact and swing time) in cross-country roller-ski skating on the field, using a single inertial measurement unit (IMU). METHODS: The developed method is based on long short-term memory neural networks to detect the initial and final contact of the poles and skis with the ground during the cyclic movements. Eleven athletes skied four laps of 2.5 km at a low and high intensity using skis with two different rolling coefficients. They were equipped with IMUs attached to the upper back, lower back and to the sternum. Data from force insoles and force poles were used as the reference system. RESULTS: The IMU placed on the upper back provided the best results, as the LSTM network was able to determine the temporal events with a mean error ranging from -1 to 11 ms and had a standard deviation (SD) of the error between 64 and 70 ms. The corresponding inner-cycle parameters were calculated with a mean error ranging from -11 to 12 ms and an SD between 66 and 74 ms. The method detected 95% of the events for the poles and 87% of the events for the skis. CONCLUSION: The proposed LSTM method provides a promising tool for assessing temporal events and inner-cycle phases in roller-ski skating, showing the potential of using a single IMU to estimate different spatiotemporal parameters of human locomotion.

The use of hydroxyapatite toothpaste to prevent dental caries.

Dissolution of hydroxyapatite from the tooth structure at low pH can lead to the irreversible destruction of enamel and dentin, which if left untreated can result in pain and tooth loss. Hydroxyapatite toothpastes contain hydroxyapatite particles in micro- or nanocrystalline form that have been shown to deposit and restore demineralized enamel surfaces. As such, they are currently being explored as a fluoride-free anti-caries agent. This narrative review article aims to summarize the recent findings of the research investigating the remineralization potential of HAP toothpaste in vitro, in situ and in vivo, as well as some other applications in dentistry.

Continuous Analysis of Marathon Running Using Inertial Sensors: Hitting Two Walls?

Marathon running involves complex mechanisms that cannot be measured with objective metrics or laboratory equipment. The emergence of wearable sensors introduced new opportunities, allowing the continuous recording of relevant parameters. The present study aimed to assess the evolution of stride-by-stride spatio-temporal parameters, stiffness, and foot strike angle during a marathon and determine possible abrupt changes in running patterns. Twelve recreational runners were equipped with a Global Navigation Satellite System watch, and two inertial measurement units clamped on each foot during a marathon race. Data were split into eight 5-km sections and only level parts were analyzed. We observed gradual increases in contact time and duty factor as well as decreases in flight time, swing time, stride length, speed, maximal vertical force and stiffness during the race. Surprisingly, the average foot strike angle decreased during the race, but each participant maintained a rearfoot strike until the end. Two abrupt changes were also detected around km 25 and km 35. These two breaks are possibly due to the alteration of the stretch-shortening cycle combined with physiological limits. This study highlights new measurable phenomena that can only be analyzed through continuous monitoring of runners over a long period of time.

Estimation of Mechanical Power Output Employing Deep Learning on Inertial Measurement Data in Roller Ski Skating.

The ability to optimize power generation in sports is imperative, both for understanding and balancing training load correctly, and for optimizing competition performance. In this paper, we aim to estimate mechanical power output by employing a time-sequential information-based deep Long Short-Term Memory (LSTM) neural network from multiple inertial measurement units (IMUs). Thirteen athletes conducted roller ski skating trials on a treadmill with varying incline and speed. The acceleration and gyroscope data collected with the IMUs were run through statistical feature processing, before being used by the deep learning model to estimate power output. The model was thereafter used for prediction of power from test data using two approaches. First, a user-dependent case was explored, reaching a power estimation within 3.5% error. Second, a user-independent case was developed, reaching an error of 11.6% for the power estimation. Finally, the LSTM model was compared to two other machine learning models and was found to be superior. In conclusion, the user-dependent model allows for precise estimation of roller skiing power output after training the model on data from each athlete. The user-independent model provides less accurate estimation; however, the accuracy may be sufficient for providing valuable information for recreational skiers.

Indirect Estimation of Breathing Rate from Heart Rate Monitoring System during Running.

Recent advances in wearable technologies integrating multi-modal sensors have enabled the in-field monitoring of several physiological metrics. In sport applications, wearable devices have been widely used to improve performance while minimizing the risk of injuries and illness. The objective of this project is to estimate breathing rate (BR) from respiratory sinus arrhythmia (RSA) using heart rate (HR) recorded with a chest belt during physical activities, yielding additional physiological insight without the need of an additional sensor. Thirty-one healthy adults performed a run at increasing speed until exhaustion on an instrumented treadmill. RR intervals were measured using the Polar H10 HR monitoring system attached to a chest belt. A metabolic measurement system was used as a reference to evaluate the accuracy of the BR estimation. The evaluation of the algorithms consisted of exploring two pre-processing methods (band-pass filters and relative RR intervals transformation) with different instantaneous frequency tracking algorithms (short-term Fourier transform, single frequency tracking, harmonic frequency tracking and peak detection). The two most accurate BR estimations were achieved by combining band-pass filters with short-term Fourier transform, and relative RR intervals transformation with harmonic frequency tracking, showing 5.5% and 7.6% errors, respectively. These two methods were found to provide reasonably accurate BR estimation over a wide range of breathing frequency. Future challenges consist in applying/validating our approaches during in-field endurance running in the context of fatigue assessment.

Ca2+ release and buffering effects of synthetic hydroxyapatite following bacterial acid challenge.

BACKGROUND: Synthetic particulate hydroxyapatite (HAP; Ca5(PO4)3(OH)) is used as ingredient in oral care products but its effects on cariogenic biofilms are not clear yet. The primary mode of action of HAP may be acting as a calcium phosphate reservoir when deposited in oral biofilms and release Ca2+ and (hydrogen) phosphate ions upon bacterial acid challenge. The aim of this in vitro study was to test this hypothesis by investigating release of Ca2+ ions and potential buffering effects from HAP upon bacterial acid challenge in planktonic cultures and biofilms of Streptococcus mutans. METHODS: Planktonic cultures of S. mutans were grown in BHI broth with 1% sucrose or with additional 5% HAP or 5% silica for up to 48 h. Separately, biofilms of S. mutans were grown in BHI for 72 h in total. After 24 h of this biofilm culture, either BHI alone or BHI with additional 0.5% HAP or 0.5% silica was added. After 48 h, BHI with 1% sucrose was added to allow bacterial acid formation. Ca2+ release was determined colorimetrically and pH measurements were performed using a pH electrode. For statistical analysis, non-parametrical procedures were applied (n ≥ 10; Mann-Whitney U test; α = 0.05). RESULTS: Relevant release of Ca2+ was only evident in planktonic cultures or biofilms with HAP but not in both other groups (p ≤ 0.001). In suspended biofilms with HAP, median pH was 4.77 after 72 h and about 0.5 pH units higher as compared to both other groups (4.28 or 4.32, respectively; p ≤ 0.001). CONCLUSIONS: Under the tested conditions, synthetic HAP releases Ca2+ ions upon bacterial acid challenge and may also show some buffering capacity but further studies are needed to investigate whether the concentrations tested here can also be reached clinically in dental biofilms.

Spinal cord high-grade infiltrating gliomas in adults: clinico-pathological and molecular evaluation.

Primary high-grade infiltrating gliomas of the spinal cord are rare, with prior series including limited numbers of cases and reporting poor outcomes. Additionally, the molecular profile of high-grade infiltrating gliomas of the spinal cord has not been well characterized. We identified 13 adult patients whose surgery had been performed at our institution over a 26-year-period. Radiologically, nine cases harbored regions of post-contrast enhancement. Existing slides were reviewed, and when sufficient tissue was available, immunohistochemical stains (IDH1-R132H, H3-K27M, H3K27-me3, ATRX, p53 and BRAF-V600E), and a targeted 150-gene neuro-oncology next-generation sequencing panel were performed. The 13 patients included 11 men and 2 women with a median age of 38 years (range = 18-69). Histologically, all were consistent with an infiltrating astrocytoma corresponding to 2016 WHO grades III (n = 5) and IV (n = 8). By immunohistochemistry, six cases were positive for H3K27M, all showing concomitant loss of H3K27-me3. Next-generation sequencing was successfully performed in ten cases. Next-generation sequencing studies were successfully performed in four of the cases positive for H3K27M by immunohistochemistry, and all were confirmed as H3F3A K27M-mutant. Additional recurrent mutations identified included those of TERT promoter (n = 3), TP53 (n = 5), PPM1D (n = 3), NF1 (n = 3), ATRX (n = 2), and PIK3CA (n = 2). No HIST1H3B, HIST1H3C, IDH1, IDH2, or BRAF mutations were detected. Ten patients have died since first surgery, with a median survival of 13 months and 1 year of 46%. Median survival was 48.5 months for H3K27M-positive cases, compared to 1 month for those with TERT promoter mutation and 77 months for those harboring neither (p = 0.019). Median survival for cases with TP53 mutations was 11.5 months and for those with PPM1D mutations was 84 months. Our findings suggest that high-grade infiltrating gliomas of the spinal cord in adults represent a heterogeneous group of tumors, with variable outcomes possibly related to their molecular profiles.

Bacterial community structure and effects of picornavirus infection on the anterior nares microbiome in early childhood.

BACKGROUND: Little is known regarding the nasal microbiome in early childhood and the impact of respiratory infection on the infants' nasal microbial composition. Here we investigated the temporal dynamics and diversity of the bacterial composition in the anterior nares in children attending daycare centers. RESULTS: For our investigation, we considered 76 parental-taken nasal swabs of 26 children (aged 13 to 36 months) collected over a study period of 3 months. Overall, there was no significant age-specific effect or seasonal shift in the nasal bacterial community structure. In a sub-sample of 14 healthy children the relative abundance of individual taxa as well as the overall diversity did not reveal relevant changes, indicating a stable community structure over the entire study period. Moreover, the nasal bacterial profiles clustered subject-specific with Bray-Curtis similarities being elevated in intra-subject calculations compared to between-subject calculations. The remaining subset of 12 children provided samples taken during picornavirus infection (PVI) and either before or after a PVI. We detected an association between the relative abundance of members of the genus Streptococcus and PV when comparing both (i) samples taken during PVI with samples out of 14 healthy children and (ii) samples taken during PVI with samples taken after PVI within the same individual. In addition, the diversity was higher during PVI than after infection. CONCLUSIONS: Our findings suggest that a personalized structure of the nasal bacterial community is established already in early childhood and could be detected over a timeframe of 3 months. Studies following infants over a longer time with frequent swab sampling would allow investigating whether certain parameter of the bacterial community, such as the temporal variability, could be related to viral infection.

Development of a New Embedded Dynamometer for the Measurement of Forces and Torques at the Ski-Binding Interface.

In alpine skiing, understanding the interaction between skiers and snow is of primary importance for both injury prevention as well as performance analysis. Risk of injuries is directly linked to constraints undergone by the skier. A force platform placed as an interface between the ski and the skier should allow a better understanding of these constraints to be obtained to thereby develop a more reliable release system of binding. It should also provide useful information to allow for better physical condition training of athletes and non-professional skiers to reduce the risk of injury. Force and torque measurements also allow for a better understanding of the skiers' technique (i.e., load evolution during turns, force distribution between left and right leg…). Therefore, the aim of this project was to develop a new embedded force platform that could be placed between the ski boot and the binding. First, the physical specifications of the dynamometer are listed as well as the measurement scope. Then, several iterations were performed on parametric 3D modeling and finite element analysis to obtain an optimal design. Two platforms were then machined and equipped with strain gauges. Finally, the calibration was performed on a dedicated test bench. The accuracy of the system was between 1.3 and 12.8% of the applied load. These results show a very good linearity of the system, which indicate a great outcome of the design. Field tests also highlighted the ease of use and reliability. This new dynamometer will allow skiers to wear their own equipment while measuring force and torque in real skiing conditions.

Drug-resistant focal epilepsy in women of childbearing age: Reproduction and the effect of epilepsy surgery.

OBJECTIVE: Women with epilepsy (WWE) have lower birth rates than expected. The reasons for this are multifactorial and involve a complex interaction between reproductive endocrine and psychosocial factors. The effect of epilepsy surgery on reproduction in women with drug-resistant focal epilepsy has not previously been studied. METHODS: Adult women of childbearing age (18-45years old) with drug-resistant focal epilepsy who had undergone a focal cortical resection between 1997 and 2008 at the Mayo Clinic in Rochester, MN were included in the study. Patients who had a history of hysterectomy or tubal ligation or who were menopausal at the time of surgery were excluded. Data on prior pregnancies and births, epilepsy history, surgical treatment, hormonal dysfunction, and socioeconomic status were obtained using a retrospective chart review. Associations between various clinical and demographic variables with changes in pregnancies and births from pre- to postsurgery were assessed using Chi-square or Fisher's exact test for categorical variables and Wilcoxon rank sum test for continuous variables. All tests were 2-sided, and p-values less than 0.05 were considered statistically significant. All analyses were performed using SAS software version 9.2 (SAS INC, Cary NC). RESULTS: One hundred and thirteen women (average age: 30.5years) were included in the study. Average length of follow-up was 5.7years (SD-3.90). Sixty-four patients (57.5%) were nulliparous at the time of surgery. Sixty-one patients (54%) had never been married. Average number of pregnancies per patient prior to surgery was 0.93, and average number of births prior to surgery was 0.73. After surgery, a total of 17 women had a total of 35 pregnancies and 25 births. The average number of pregnancies and births after surgery was 1.27 and 0.96, respectively. Infertility was reported in one patient postoperatively. Patients who were younger at the time of surgery experienced a greater change in the number of pregnancies and births after surgery (p=0.0036 and 0.0060, respectively). Patients who received fewer antiepileptic drug medication trials by the time of surgery also had a greater change in the number of births after surgery (p=0.0362). Seizure onset localization and lateralization, presurgical seizure frequency, age at seizure onset, duration of epilepsy, and postoperative seizure outcome were not statistically significant factors. CONCLUSION: The present retrospective observational study provides additional evidence for the importance of early surgical treatment in women with drug-resistant focal epilepsy. Patients who had received fewer medications prior to surgery were more likely to experience an increase in births following surgery. The significance of these findings requires further investigation but may support a role for earlier surgical intervention in the management of drug-resistant focal epilepsy.

Case Report on Caries Assessment Using Intraoral Scanner Compared with Bitewing Radiographs.

Dental caries remains one of the main reasons patients seeing their dentist. They either show up for preventive measures, diagnostics, or treatment of present caries lesions. To date, diagnostics are performed visually, supported by using bitewing radiographs. While radiographic diagnostics should only be performed on a biannual basis, and some caries process will not be seen with visual diagnostics, there remains a lack in regular checkups. Therefore, different technical applications can be used for regular diagnostics. One of those is the near-infrared imaging (NIRI) technology. In this case report, a patient presented with incipient caries lesions. These lesions were diagnosed visually, radiographically, and using NIRI. After diagnosis of incipient caries lesions, the patient was advised to use a hydroxyapatite toothpaste and a hydroxyapatite gel for the remineralization of the lesions and prevention of caries progression. The patient was followed up for 6 months with regular checkups in between. Visual diagnostics and NIRI were used to detecting the caries progress. After 6 months, bitewing radiographs were used in addition. In this clinical investigation we were able to show for the first time that NIRI and bitewing radiographs are able to detect and follow incipient caries lesions. Additionally, this study highlights that hydroxyapatite-containing oral care products are able to arrest and remineralize the caries process.

Peak Oxygen Uptake is Slope Dependent: Insights from Ground Reaction Forces and Muscle Oxygenation in Trained Male Runners.

BACKGROUND: The aim of this study is to explore the effect of treadmill slope on ground reaction forces and local muscle oxygenation as putative limiting factors of peak oxygen uptake in graded maximal incremental running tests. Thirteen trained male runners completed five maximal incremental running tests on treadmill at - 15%, - 7.5%, 0%, 7.5% and 15% slopes while cardiorespiratory and local muscle oxygenation responses as well as ground reaction forces were continuously recorded. Blood lactate concentration and isometric knee extensor torque were measured before and after each test. RESULTS: Peak oxygen uptake was lower at - 15% slope compared to all other conditions (from - 10 to - 17% lower, p < 0.001), with no difference between - 7.5 and + 15% slope. Maximal heart rate and ventilation values were reached in all conditions. The negative external mechanical work increased from steep uphill to steep downhill slopes (from 6 to 92% of total external work) but was not correlated with the peak oxygen uptake reduction. Local muscle oxygenation remained higher in - 15% slope compared to level running (p = 0.003). CONCLUSIONS: Similar peak oxygen uptake can be reached in downhill running up to - 7.5% slope. At more severe downhill slopes (i.e., - 15%), greater negative muscle work and limited local muscle deoxygenation occurred, even in subjects familiarized to downhill running, presumably preventing the achievement of similar to other condition's peak oxygen uptake. KEY POINTS: Trained male runners can reach like level running V̇O2peak at moderate but not at severe negative slope. Negative external mechanical work increases with increasing negative slope. At maximal intensity Vastus Lateralis muscle oxygenation is higher in steep negative slope. Knee extensor isometric muscle torque is preserved after maximal level and uphill running, but reduced after downhill running, despite lower blood lactate. Progressive reduction of V̇O2 at maximal effort with increasing negative slope might be related to the metabolic consequences of increased lower limb negative external work (i.e., eccentric muscle actions).

Prevention of Dental Caries: A Review on the Improvements of Toothpaste Formulations from 1900 to 2023.

Modern toothpastes are complex formulations with various ingredients. The aim of this study was to analyze the improvement of toothpaste formulations from 1900 to 2023 focusing on active ingredients with remineralizing, antibacterial, or plaque-removing effects, and to discuss their influence on caries prevention. For this, worldwide patent applications were searched using the international database Espacenet from the European Patent Office. Additionally, toothpaste products were searched using the Mintel product database from 1996 to 2023. The searched ingredients were (in alphabetical order): calcium carbonate, calcium phosphates, hydrated silica, sodium fluoride, sodium lauryl sulfate, triclosan, xylitol, and zinc salts as they are known from the scientific literature to be remineralizing or antibacterial/antiplaque agents. It was shown that the number of patent applications containing these ingredients significantly increased since the 1970s. As these ingredients have remineralizing, antibacterial, or plaque-removing effects, they all can contribute to caries prevention. In conclusion, and within the limitations of this approach, this study shows that toothpaste formulations have greatly improved over the past decades by using various active anticaries ingredients.

Caries Etiology and Preventive Measures.

Caries is a widespread disease in both children and adults. Caries is caused by the conversion of fermentable carbohydrates by plaque bacteria into acids on the tooth surface. Thus, it is important to focus on sugar reduction and plaque control. For efficient plaque removal/control, state-of-the-art toothpastes contain various active ingredients such as antimicrobial agents (e.g., chlorhexidine, stannous salts, and zinc salts), abrasives (e.g., calcium carbonate, calcium phosphates, and hydrated silica), surfactants (e.g., sodium lauryl sulfate and sodium methyl cocoyl taurate), and natural compounds (e.g., polyphenols and xylitol). Agents with pH-buffering and calcium-releasing properties (e.g., calcium carbonate and calcium phosphates) and biomimetic actives (e.g., hydroxyapatite) reverse the effects of the acids. Additionally, modern toothbrushes (i.e., electric toothbrushes) as well as dental floss and interdental brushes significantly help remove plaque from dental surfaces including interproximal surfaces. In conclusion, modern concepts in caries prevention should focus not only on tooth remineralization alone but also on the control of all the key factors involved in caries development.

Predicting long-term outcomes after microvascular decompression for hemifacial spasm according to lateral spread response and immediate postoperative outcomes: a cohort study.

OBJECTIVE: Microvascular decompression (MVD) is a well-established and highly effective treatment option for hemifacial spasm (HFS). Lateral spread response (LSR) has been used as an intraoperative indicator of HFS resolution, with controversial reliability. The purpose of this study was to determine long-term outcomes of MVD for HFS and the role of LSR and other preoperative predictors. METHODS: The authors conducted a cohort study of all patients treated with MVD for HFS at a single institution from January 1, 1998, to December 31, 2019. In addition to a retrospective chart review, all patients were contacted at the time of the study to provide informed consent and responded to a telephone survey to ascertain their current disease and medication status. Patients with at least 12 months of postoperative follow-up were included. Statistical testing included a Student t-test, Fisher's exact test, logistic regression, and Cox proportional hazards analysis. RESULTS: One hundred nineteen patients met study criteria; 41 (34%) had at least 10 years of clinical follow-up. HFS fully resolved in 93 (78%), symptoms subjectively improved in 11 (9%) and were unchanged in 15 (13%). Immediate postoperative HFS status did not correlate with long-term outcome (p = 0.13). Changes in LSR were not associated with outcome. Patients receiving neuromodulating agents had significantly longer preoperative duration of symptoms and were more likely to show persistent LSR intraoperatively. HFS recurrence was associated with younger age at the time of surgery but not with intraoperative LSR resolution. CONCLUSIONS: This study demonstrated that MVD for HFS is highly effective for most patients. Neither intraoperative LSR change nor immediate postoperative status was predictive of long-term outcomes.

Doses of fluoride toothpaste for children up to 24 months.

AIM: The aim of this study was to test the dose of fluoride toothpaste by parents for their children aged up to 24 months. METHODS: Parents who use fluoride toothpastes for their children were asked to dose two commercially available toothpastes (A and B) with 1000 ppm fluoride each for their children as they would normally do at home. The toothpaste amounts were weighed, and as reference, the weight of an 'optimal' grain of rice-size amount of each toothpaste was used. RESULTS: 61 parents dosed a mean of 0.263 ± 0.172 g toothpaste A and 0.281 ± 0.145 g toothpaste B. The parents' mean doses were 5.9 times higher for toothpaste A and 7.2 times higher for toothpaste B than an 'optimal' grain of rice-size amount (the reference dose as recommended). The difference between parent's and reference dose was statistically significant (p < 0.001). Moreover, 39.3% of parents were not aware about conditions of use and warnings that have to be printed on the package of fluoride toothpastes. CONCLUSION: In this study, parents significantly overdosed the toothpaste for their children. To avoid fluoride intake from toothpaste, parents can choose fluoride-free alternatives for the oral care of their infants and toddlers.

The association between Dioscorea sansibarensis and Orrella dioscoreae as a model for hereditary leaf symbiosis.

Hereditary, or vertically-transmitted, symbioses affect a large number of animal species and some plants. The precise mechanisms underlying transmission of functions of these associations are often difficult to describe, due to the difficulty in separating the symbiotic partners. This is especially the case for plant-bacteria hereditary symbioses, which lack experimentally tractable model systems. Here, we demonstrate the potential of the leaf symbiosis between the wild yam Dioscorea sansibarensis and the bacterium Orrella dioscoreae (O. dioscoreae) as a model system for hereditary symbiosis. O. dioscoreae is easy to grow and genetically manipulate, which is unusual for hereditary symbionts. These properties allowed us to design an effective antimicrobial treatment to rid plants of bacteria and generate whole aposymbiotic plants, which can later be re-inoculated with bacterial cultures. Aposymbiotic plants did not differ morphologically from symbiotic plants and the leaf forerunner tip containing the symbiotic glands formed normally even in the absence of bacteria, but microscopic differences between symbiotic and aposymbiotic glands highlight the influence of bacteria on the development of trichomes and secretion of mucilage. This is to our knowledge the first leaf symbiosis where both host and symbiont can be grown separately and where the symbiont can be genetically altered and reintroduced to the host.

Pathological and physiological high-frequency oscillations in focal human epilepsy.

High-frequency oscillations (HFO; gamma: 40-100 Hz, ripples: 100-200 Hz, and fast ripples: 250-500 Hz) have been widely studied in health and disease. These phenomena may serve as biomarkers for epileptic brain; however, a means of differentiating between pathological and normal physiological HFO is essential. We categorized task-induced physiological HFO during periods of HFO induced by a visual or motor task by measuring frequency, duration, and spectral amplitude of each event in single trial time-frequency spectra and compared them to pathological HFO similarly measured. Pathological HFO had higher mean spectral amplitude, longer mean duration, and lower mean frequency than physiological-induced HFO. In individual patients, support vector machine analysis correctly classified pathological HFO with sensitivities ranging from 70-98% and specificities >90% in all but one patient. In this patient, infrequent high-amplitude HFO were observed in the motor cortex just before movement onset in the motor task. This finding raises the possibility that in epileptic brain physiological-induced gamma can assume higher spectral amplitudes similar to those seen in pathologic HFO. This method if automated and validated could provide a step towards differentiating physiological HFO from pathological HFO and improving localization of epileptogenic brain.