Synaptic influences of pontine nuclei on cochlear nucleus cells

Using the in vitro isolated whole brain preparation of the guinea pig, we tested the synaptic effects induced by the stimulation of pontine nuclei (PN) in intracellularly recorded and stained principal cells of the cochlear nucleus (CN). Twenty percent of the recorded cells in all CN subdivisions responded to stimulation of either ipsilateral or contralateral PN, and 12% of the cells exhibited convergence of inputs from both sides. The responses were recorded only in stellate cells of the ventral CN and in the pyramidal cells of the dorsal CN, whereas no responses were observed in bushy, octopus, and giant cells. PN stimulation produced excitatory and inhibitory postsynaptic potentials as well as mixed responses. The heterogeneous nature and the wide latency range (3.2-18ms) of observed responses suggest significant variability in the underlying synaptic mechanisms and the implicated pathways. We propose that PN projections to the CN, terminating mainly in the granule cell domain (GCD), together with other non-auditory and auditory inputs contribute to multimodal convergence in the GCD leading ultimately to modulatory actions on the output activity of CN principal cell

Discharge properties of identified cochlear nucleus neurons and auditory nerve fibers in response to repetitive electrical stimulation of the auditory nerve

Using the in vitro isolated whole brain preparation of the guinea pig maintained at 29°C, we intracellularly recorded and stained cochlear nucleus (CN) neurons and auditory nerve (AN) fibers. Discharge properties of CN cells and AN axons were tested in response to 50-ms trains of electrical pulses delivered to the AN at rates ranging from 100 to 1000 pulses per second (pps). At low stimulation rates (200-300pps), the discharges of AN fibers and a large proportion of principal cells (bushy, octopus, stellate) in the ventral cochlear nucleus (VCN) followed with high probability each pulse in the train, resulting in synchronization of discharges within large populations of AN fibers and CN cells. In contrast, at high stimulation rates (500pps and higher), AN fibers and many VCN cells exhibited "primary-like", "onset" and some other discharge patterns resembling those produced by natural sound stimuli. Unlike cells in the VCN, principal cells (pyramidal, giant) of the dorsal CN did not follow the stimulating pulses even at low rates. Instead, they often showed "pauser" and "build-up" patterns of activity, characteristic for these cells in conditions of normal hearing. We hypothesize that, at low stimulation rates, the response behavior of AN fibers and VCN cells is different from the patterns of neuronal activity related to normal auditory processing, whereas high stimulation rates produce more physiologically meaningful discharge patterns. The observed differences in discharge properties of AN fibers and CN cells at different stimulation rates can contribute to significant advantages of high- versus low-rate electrical stimulation of the AN used for coding sounds in modern cochlear implant

Аналіз післяопераційного періоду при первинному ендопротезуванні кульшового суглоба переломів проксимального відділу стегна в залежності від дренування післяопераційної рани

Drainage of postoperative wounds for a long time remained the obligatory stage of operative intervention at arthroplasty of a hip joint. But recently in many clinics there are a tendency for a total refusal from this stage. The results of the research highlight only the positive features of these changes, but our experience has shown both an improvement and a decrease in the outcome of treatment.The aim of the research is to establish the expediency of refusing to drain postoperative wounds after hip replacement with fractures of the proximal thigh.Material and methods. The analysis of 44 patients with fractures of the proximal thigh after the initial replacement with unipolar prothesis with a dual movement head was performed. Representative groups have been formed depending on the use of post-operative wound layer drainage. In the postoperative period, an assessment of pain syndrome for VAS was used. We applied a visual assessment of health (EQ VAS) and questionnaires EQ-5D-5L. Hidden blood loss = BCC x (hematocrit before - hematocrit after), where hematocrit before is the value of the indicator for the operation, hematocrit after - the value of the index for 7 days after the operation. The determination of the volume of circulating blood (BCC) was carried out using the formula by Nadler, Hidalgo and Bloch: PBV=K1×height (m)3+K2×weight (kg)+K3, where K1=0.3669, K2=0.03219, K3=0.6041 for men; K1=0.3561, K2=0.03308, K3=0.1833 for women.Results. The intensification of pain syndrome was detected up to 3 days after the postoperative term in the case of failure of layer drainage. There was no statistically significant difference in the indicators of the quality of life assessment, but the patient's ability to raise the straightened limb with refusal of drainage was observed more often than 2 days compared with 4 days in patients who performed layered drainage of postoperative wound. Significantly improved hemodynamic rates to 7 days of the postoperative period and consequently reduced blood loss. Twice times more often, hyperemia of the postoperative wound was observed in the event of withdrawal from drainage. Increase the length of the hip circumference and regress to 7 days. According to the assessment of the questionnaire EQ-5D-5L, there was no statistically significant difference in the assessment of the quality of life of the affected, depending on drainage.Conclusions. Denial from drainage improves hemodynamic rates in the postoperative period in the study group, slightly increasing the pain syndrome from the first to the third day. Refusal from the layered drainage of the postoperative wound with the fractures of the proximal thigh section in the primary arthroplasty is reasonableДренирование послеоперационной раны долгое время оставалось обязательным этапом оперативного вмешательства при эндопротезировании тазобедренного сустава. Но в последнее время во многих клиниках приобретает тенденция тотального отказа от этого этапа. Результаты исследований освещают только положительные черты этих изменений, но наш опыт показал как улучшение так и снижение показателей результата лечения.Цель исследования. Установить целесообразность отказа от дренирования послеоперационной раны после эндопротезирования тазобедренного сустава при переломах проксимального отдела бедра.Материал и методы. Проведен анализ 44 пострадавших с переломами проксимального отдела бедра после первичного эндопротезирования биполярными протезами. Сформированные репрезентативные группы в зависимости от применения послойного дренирование послеоперационной раны. В послеоперационном периоде применялась оценка болевого синдрома по ВАШ. Применяли визуальную оценку состояния здоровья (EQ VAS), анкетирование EQ-5D-5L. Скрытая кровопотеря = ОЦК х (гематокрит до – гематокрит после), где гематокрит к – значение показателя к операции, гематокрит после – значение показателя на 7 сутки после операции. Определение объема циркулирующей крови (ОЦК) проводили по формуле Nadler, Hidalgo and Bloch: PBV=К1×рост (м) 3 + K2×вес (кг) + K3, где K1=0.3669, K2=0.03219, K3=0.6041 для мужчин; К1=0,3561, K2=0,03308, K3=0,1833 для женщин.Результаты. Выявлено усиление болевого синдрома до 3 суток послеоперационного срока при отказе от послойного дренирования. Не мало статистической достоверной разницы в показателях оценки качества жизни, но возможность больного поднять выпрямленную конечность при отказе от дренирования наблюдали чаще всего до 2 суток по сравнению с 4 временем у больных, которым выполняли послойное дренирование послеоперационной раны. Значительно улучшились показатели гемоконцентрация к 7 суткам послеоперационного периода и соответственно была снижена скрытая кровопотеря. Вдвое чаще наблюдали гиперемию послеоперационной раны в случае отказа от дренирования. Увеличение длины окружности бедра и регресс к 7 суткам. По оценке анкетирование EQ-5D-5L не обнаружено статистически достоверной разницы в оценке качества жизни пострадавших в зависимости от дренирования.Выводы. Отказ от дренирования улучшает показатели гемоконцентрация в послеоперационном периоде изучаемой группы, незначительно усиливает болевой синдром с первой до третьей суток. Целесообразен отказ от послойного дренирования послеоперационной раны пострадавшим с переломами проксимального отдела бедра при первичном эндопротезированииДренування післяопераційної рани довгий час залишалось обов’язковим етапом оперативного втручання при ендопротезуванні кульшового суглоба. Але останнім часом в багатьох клініках набуває тенденція тотальної відмови від цього етапу. Результати досліджень висвітлюють тільки позитивні риси від цих змін але наш досвід виявив як поліпшення так і зниження показників результату лікування. Мета дослідження. Встановити доцільність відмови від дренування післяопераційної рани після ендопротезування кульшового суглоби при переломах проксимального відділу стегна.Матеріал та методи. Проведено аналіз 44 постраждалих з переломами проксимального відділу стегна після первинного ендопротезування біполярними протезами. Сформовані репрезентативні групи в залежності від застосування пошарового дренування післяопераційної рани. В післяопераційному періоді застосовувалась оцінка больового синдрому за ВАШ. Застосовували візуальну оцінку стану здоров’я (EQ VAS), анкетування EQ-5D-5L. Прихована крововтрата = ОЦК х (гематокрит до – гематокрит після), де гематокрит до – значення показника до операції, гематокрит після – значення показника на 7 добу після операції. Визначення об’єму циркулюючої крові (ОЦК) проводили за формулою Nadler, Hidalgo and Bloch: PBV=К1×зріст (м)3+ K2×вага(кг)+K3, де K1=0.3669, K2=0.03219, K3=0.6041 для чоловіків; К1=0,3561, K2=0,03308, K3=0,1833 для жінок.Результати. Виявлено посилення больового синдрому до 3 доби післяопераційного терміну при відмові від пошарового дренування. Не мало статистичної достовірної різниці у показниках оцінки якості життя, але можливість хворого підняти випрямлену кінцівку при відмові від дренування спостерігали найчастіше до 2 доби в порівнянні з 4 добою у хворих котрим виконували пошарове дренування післяопераційної рани. Значно покращились показники гемоконцентрації к 7 добі післяопераційного періоду та відповідно була знижена прихована крововтрата. Вдвічі частіше спостерігали гіперемію післяопераційної рани у випадку відмови від дренування. Збільшення довжини окружності стегна та регрес к 7 добі. За оцінкою анкетування EQ-5D-5L не виявлено статистично достовірної різниці в оцінці якості життя постраждалих в залежності від дренування.Висновки. Відмова від дренування поліпшує показники гемоконцентрації в післяопераційному періоді у вивчаємої групи, незначно посилює больовий синдром з першої до третьої доби. Доцільна відмова від пошарового дренування післяопераційної рани постраждалим з переломами проксимального відділу стегна при первинному ендопротезуванн

Total spondylectomy in surgical treatment of primary and localized secondary tumors of the thoracic and lumbar spine

Effective treatment of primary and localized secondary tumors of thoracic and lumbar spine is one of complex problem in spinal surgery. Lack of surgical radicalism with leaving tumor fragment in situ due to problems of differentiation tumor and non-tumor tissue, absence of clear dissection plane are the main causes of high rate of local neoplastic recurrence, up to 54–89% according to literature data. Wide and marginal tumor resection with obeying principles of oncologic barriers and compartment is the only method of surgical prophylaxis of local recurrence. Development of total spondylectomy technique in surgical treatment of primary and localized secondary tumors of thoracic and lumbar spine is the way to achieve maximal control of aggressive spine tumors growth

Parvalbumin-expressing ependymal cells in rostral lateral ventricle wall adhesions contribute to aging-related ventricle stenosis in mice

Aging-associated ependymal-cell pathologies can manifest as ventricular gliosis, ventricle enlargement, or ventricle stenosis. Ventricle stenosis and fusion of the lateral ventricle (LV) walls is associated with a massive decline of the proliferative capacities of the stem cell niche in the affected subventricular zone (SVZ) in aging mice. We examined the brains of adult C57BL/6 mice and found that ependymal cells located in the adhesions of the medial and lateral walls of the rostral LVs upregulated parvalbumin (PV) and displayed reactive phenotype, similarly to injury-reactive ependymal cells. However, PV+ ependymal cells in the LV-wall adhesions, unlike injury-reactive ones, did not express glial fibrillary acidic protein. S100B+/PV+ ependymal cells found in younger mice diminished in the LV-wall adhesions throughout aging. We found that periventricular PV-immunofluorescence showed positive correlation to the grade of LV stenosis in nonaged mice (10-month-old) PV-knock out (PV-KO) mice. This suggests an involvement of PV+ ependymal cells in aging-associated ventricle stenosis. Additionally, we observed a time-shift in microglial activation in the LV-wall adhesions between age-grouped PV- KO and wild-type mice, suggesting a delay in microglial activation when PV is absent from ependymal cells. Our findings implicate that compromised ependymal cells of the adhering ependymal layers upregulate PV and display phenotype shift to “reactive” ependymal cells in aging-related ventricle stenosis; moreover, they also contribute to the progression of LV-wall fusion associated with a decline of the affected SVZ-stem cell niche in aged mice

Reduction in 50-kHz call-numbers and suppression of tickling-associated positive affective behaviour after lesioning of the lateral hypothalamic parvafox nucleus in rats

The parvafox nucleus is located ventrolaterally in the lateral hypothalamic area (LHA). Its core and shell are composed of neurons expressing the calcium-binding protein parvalbumin (PV) and the transcription factor Foxb1, respectively. Given the known functions of the LHA and that the parvafox nucleus receives afferents from the lateral orbitofrontal cortex and projects to the periaqueductal gray matter, a functional role of this entity in the expression of positive emotions has been postulated.The purpose of the present study was to ascertain whether the deletion of neurons in the parvafox nucleus influenced the tickling-induced 50-kHz calls, which are thought to reflect positive affective states, in rats. To this end, tickling of the animals (heterospecific play) was combined with intracerebral injections of the excitotoxin kainic acid into the parvafox nucleus.The most pronounced surgery-associated reduction in 50-kHz call-numbers was observed in the group of rats in which, on the basis of PV-immunoreactive-cell counts in the parvafox nucleus, bilateral lesions had been successfully produced. Two other parameters that were implemented to quantify positive affective behaviour, namely, an approach towards and a following of the hand of the tickling experimenter, were likewise most markedly suppressed in the group of rats with bilaterally successful lesions. Furthermore, positive correlations were found between each of the investigated parameters. Our data afford evidence that the parvafox nucleus plays a role in the production of 50-kHz calls in rats, and, more generally, in the expression of positive emotions

Аналіз напружено-деформованого стану моделей вертлюгових переломів стегнової кістки типу 5 за Евансом після ендопротезування

Aim of research: to develop the mathematical model of trochanteric fractures of a femur by Evans’ classification and to use it for studying main directions of loading the proximal femur section at endoprosthesis with the additional fixation of fragments by needles.Materials and methods of research. For solving the set task, we developed the mathematical models of a femur with trochanteric fractures of different types by Evans’ classification. We modeled trochanteric fractures of a femoral bone of 5 type by Evans, using the standard endoprosthesis, fixing separate fragments and model endoprosthesis of the offered construction.Results. The loading results were obtained. At using the endoprosthesis, the zone of maximal loads covers its neck and is 97,6 МPа on its upper surface and 118,4 МPа – on the low one. The least loaded zone is the little trochanter area, where the load value is only 1,0 МPа, and adjacent zones, where tensions don’t exceed the value 10,0 МPа. The diaphyseal part of a femur is characterized with the tension values at the level from 21,1 to 23,8 МPа. At using the model system, the most tension level (88,2 МPа) is observed in the upper part of the neck. Tensions in other control points are distributed evenly and don’t exceed the value 25,4 МPа by absolute values in the femoral diaphase and 17,3 МPа in the fracture zone.Conclusions. At modeling variants of endoprosthesis of the proximal section of a femur with trochanteric fractures of 5 type by Evans’ classification, it was determined, that the model system at all fracture types allows to lower a tension in practically all control points of bone elements of the models essentially. Elements of metal constructions demonstrate zones of higher tensions, where they are rather higher than in the model with the endoprosthesis at the expanse of the essentially less hardness in the node of connecting the carrying pivot with the intramedullary oneУ статті проведено аналіз за допомогою розроблених кінцеве елементних моделей перелому вертелюгової ділянки 5 типу за класифікацією Еванса зон напруження при використанні запатентованого авторами модульного фіксатора-протеза та стандартного ендопротеза кульшового суглоба з головкою подвійної рухомості. Виявлено значне зниження навантаження в кісткових елементах при використанні модульного фіксатора-протеза у порівнянні зі стандартною конструкціє

The projection from auditory cortex to cochlear nucleus in guinea pigs: an in vivo anatomical and in vitro electrophysiological study

Previous anatomical experiments have demonstrated the existence of a direct, bilateral projection from the auditory cortex (AC) to the cochlear nucleus (CN). However, the precise relationship between the origin of the projection in the AC and the distribution of axon terminals in the CN is not known. Moreover, the influence of this projection on CN principal cells has not been studied before. The aim of the present study was two-fold. First, to extend the anatomical data by tracing anterogradely the distribution of cortical axons in the CN by means of restricted injections of biotinylated dextran amine (BDA) in physiologically characterized sites in the AC. Second, in an in vitro isolated whole brain preparation (IWB), to assess the effect of electrical stimulation of the AC on CN principal cells from which intracellular recordings were derived. BDA injections in the tonotopically organized primary auditory cortex and dorsocaudal auditory field at high and low best frequency (BF) sites resulted in a consistent axonal labeling in the ipsilateral CN of all injected animals. In addition, fewer labeled terminals were observed in the contralateral CN, but only in the animals subjected to injections in low BF region. The axon terminal fields consisting of boutons en passant or terminaux were found in the superficial granule cell layer and, to a smaller extent, in the three CN subdivisions. No axonal labeling was seen in the CN as result of BDA injection in the secondary auditory area (dorsocaudal belt). In the IWB, the effects of ipsilateral AC stimulation were tested in a population of 52 intracellulary recorded and stained CN principal neurons, distributed in the three CN subdivisions. Stimulation of the AC evoked slow late excitatory postsynaptic potentials (EPSPs) in only two cells located in the dorsal CN. The EPSPs were induced in a giant and a pyramidal cell at latencies of 20ms and 33ms, respectively, suggesting involvement of polysynaptic circuits. These findings are consistent with anatomical data showing sparse projections from the AC to the CN and indicate a limited modulatory action of the AC on CN principal cell

The orbitofrontal cortex projects to the parvafox nucleus of the ventrolateral hypothalamus and to its targets in the ventromedial periaqueductal grey matter

Although connections between the orbitofrontal cortex (OFC)—the seat of high cognitive functions—the lateral hypothalamus and the periaqueductal grey (PAG) have been recognized in the past, the precise targets of the descending fibres have not been identified. In the present study, viral tracer-transport experiments revealed neurons of the lateral (LO) and the ventrolateral (VLO) OFC (homologous to part of Area 13 in primates) to project to a circumscribed region in the ventrolateral hypothalamus, namely, the horizontally oriented, cylindrical parvalbumin- and Foxb1- expressing (parvafox) nucleus. The fine collaterals stem from coarse axons in the internal capsule and form excitatory synapses specifically with neurons of the parvafox nucleus, avoiding the rest of the hypothalamus. In its further caudal course, this contingent of LO/VLO-axons projects collaterals to the Su3- and the PV2 nuclei, which lie ventral to the aqueduct in the (PAG), where the terminals fields overlap those deriving from the parvafox nucleus itself. The targeting of the parvafox nucleus by the LO/VLO-projections, and the overlapping of their terminal fields within the PAG, suggest that the two cerebral sites interact closely. An involvement of this LO/VLO- driven circuit in the somatic manifestation of behavioural events is conceivable

Multisensory integration in the dorsal cochlear nucleus: unit responses to acoustic and trigeminal ganglion stimulation

A necessary requirement for multisensory integration is the convergence of pathways from different senses. The dorsal cochlear nucleus (DCN) receives auditory input directly via the VIIIth nerve and somatosensory input indirectly from the Vth nerve via granule cells. Multisensory integration may occur in DCN cells that receive both trigeminal and auditory nerve input, such as the fusiform cell. We investigated trigeminal system influences on guinea pig DCN cells by stimulating the trigeminal ganglion while recording spontaneous and sound-driven activity from DCN neurons. A bipolar stimulating electrode was placed into the trigeminal ganglion of anesthetized guinea pigs using stereotaxic co-ordinates. Electrical stimuli were applied as bipolar pulses (100 s per phase) with amplitudes ranging from 10 to 100 A. Responses from DCN units were obtained using a 16-channel, four-shank electrode. Current pulses were presented alone or preceding 100- or 200-ms broadband noise (BBN) bursts. Thirty percent of DCN units showed either excitatory, inhibitory or excitatory inhibitory responses to trigeminal ganglion stimulation. When paired with BBN stimulation, trigeminal stimulation suppressed or facilitated the firing rate in response to BBN in 78% of units, reflecting multisensory integration. Pulses preceding the acoustic stimuli by as much as 95 ms were able to alter responses to BBN. Bimodal suppression may play a role in attenuating body-generated sounds, such as vocalization or respiration, whereas bimodal enhancement may serve to direct attention in low signal-to-noise environments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72293/1/j.1460-9568.2005.04142.x.pd