Direct identification of ventrointermediate nucleus of the thalamus on magnetic resonance and computed tomography images

OBJECTIVE

The ventro-intermediate (Vim) nucleus of the thalamus is a commonly used target for the treatment of tremor. The thalamic fasciculus contains myelinated fibers, believed to play a role in the generation of tremor, that converge into a dense bundle at the inferior aspect of the Vim nucleus, making it visible on magnetic resonance (MR) and computed tomography (CT) images. This structure, therefore, can be visualized directly and targeted for thalamotomy.

METHODS

Thalamotomies were performed on nine patients (who have a follow-up of 13–23 months) with parkinsonian and essential tremors using MR and CT images. The tremor target was hypointense on MR images obtained in inversion recovery sequence and hypointense on CT images. It was therefore visualized, directly targeted, and probed. Stimulation studies were done to physiologically confirm accuracy of the probe placement and then a radiofrequency lesion was made.

RESULTS

Stimulation of the target identified as the Vim nucleus on MR and CT images produced responses similar to those expected from the Vim nucleus. After this site was lesioned tremor disappeared in all nine patients.

CONCLUSION

The Vim nucleus of the thalamus is visible on MR and CT images. Destruction of this target abolishes parkinsonian and essential tremors.     

Quantification and visualization of three-dimensional inconsistency of the ventrointermediate nucleus of the thalamus in the Schaltenbrand-Wahren brain atlas

Summary   Background. This work quantifies and visualises 3D inconsistencies of the ventrointermediate nucleus (VIM) of the thalamus, including the VIM externum (VIMe) and VIM internum (VIMi), in the Schaltenbrand-Wahren (SW) brain atlas. Method. For each VIM, VIMe, VIMi the 3D models, 3D-A, 3D-C and 3D-S were reconstructed from the SW axial, coronal and sagittal microseries, respectively, by applying a shape-based method. All 3D models, placed in the SW coordinate system, were compared quantitatively in terms of location (centroids), size (volumes), shape (normalised eigen values), orientation (eigen vectors), and mutual spatial relationships (overlaps and inclusions). Findings. The reconstructed 3D models differ significantly in location, size, shape, and inclusion rate. The centroid of 3D-A/VIM differs considerably from those of 3D-C/VIM and 3D-S/VIM. The difference between the centroids of 3D-C/VIM and 3D-S/VIM is in laterality only: that of 3D-C/VIM is located more medially (11.85 mm) than that of 3D-S/VIM (14.62 mm). 3D-A/VIM has the smallest volume (69.00 mm³); 3D-C/VIM is 3.71 and 3D-S/VIM 3.89 times larger. The overlap is also highly variable: 104.88 mm³ for 3D-C/VIM with 3D-S/VIM, and very low (3.22 and 7.45 mm³) when 3D-A/VIM is involved. The highest inclusion rate is for 3D-C/VIM with 3D-S/VIM (39.10 and 40.97%) and the lowest for 3D-A/VIM with 3D-C/VIM (1.26 and 4.66%). The centroid of 3D-A/VIMe differs noticeably from those of 3D-C/VIMe and 3D-S/VIMe. The difference between the centroids of 3D-C/VIMe and 3D-S/VIMe is mainly in laterality: that of 3D-C/VIMe is located more medially (12.91 mm) than that of 3D-S/VIMe (16.65 mm). 3D-A/VIMe has the smallest volume (49.87 mm³); 3D-S/VIMe is 3.24 and 3D-C/VIMe 3.36 times larger. The overlap sizes are low: 32.72 mm³ for 3D-C/VIMe with 3D-S/VIMe, and very low (1.32 and 2.01 mm³) when 3D-A/VIMe is involved. The inclusion rates are also low: the highest is for 3D-C/VIMe with 3D-S/VIMe (19.53 and 20.29%) and the lowest for 3D-A/VIMe with 3D-C/VIMe (1.19 and 4.01%). Lateral scaling of the coronal microseries by 1.2897 to match the 3D-C/VIMe and 3D-S/VIMe centroids increases the inclusion rates for the sagittal microseries by more than twice. The volume of scaled 3D-C enlarges to 216.24 mm³ which is 1.34 bigger than that of 3D-S. There are substantial differences among the centroids of 3D-A/VIMi, 3D-C/VIMi and 3D-S/VIMi. The centroid of 3D-A/VIMi is located more anteriorly (−1.92 mm) than that of 3D-C/VIMi (−5.02 mm). The centroid of 3D-A/VIMi is located more ventrally (2.88 mm) than those of 3D-C/VIMi and 3D-S/VIMi (each at 5.34 mm). 3D-A/VIMi has the smallest volume (19.75 mm³); 3D-S/VIMi is 3.23 and 3D-C/VIMi 4.30 times larger. 3D-A/VIMi practically does not overlap with 3D-C/VIMi and 3D-S/VIMi. The inclusion rates for 3D-C/VIMi with 3D-S/VIMi are medium (32.63 and 43.43%). Conclusion. Each VIM, VIMe, VIMi as reconstructed from the SW atlas has a significant 3D inaccuracy within each orientation and across them. Therefore, absolute and direct reliance on the original SW atlas is unreliable and unsafe, and this atlas has to be used with great care and understanding of its strengths and limitations. Correspondence: Wieslaw L. Nowinski, DSc, PhD, Biomedical Imaging Lab, Agency for Science Technology and Research, 30 Biopolis Street, #07-01 Matrix, 138671 Singapore.     

A model of intrinsic sphincteric deficiency in the rat: electrocauterization

AIMS: Intrinsic sphincteric deficiency (ISD) denotes a malfunction of the distal urethral sphincter. Our objective was to produce a durable model of ISD in the rat. METHODS: Surrounding tissues lateral to the mid-urethra were cauterized to produce sphincteric injury in 24 adult female Sprague-Dawley rats. The rats were divided into four groups of six rats each and followed for 2, 4, 6, and 16 weeks. Sphincteric function was studied by using the vertical tilt table/intravesical pressure clamp model to measure leak point pressures (LPPs). Muscle and nerve damage were assessed with hematoxylin and eosin (H&E) and anti-protein gene product (PGP) 9.5 staining, respectively. As a control, 12 rats underwent a sham operation and subsequent LPP testing at 2, 4, 6, and 16 weeks. RESULTS: The mean LPPs of the rats 2, 4, 6, and 16 weeks after cauterization were 18.7 +/- 0.8 cm H2O, 27.6 +/- 1.6 cm H2O, 24.3 +/- 1.7 cm H2O, and 19.1 +/- 2.2 cm H2O, respectively. The mean LPPs of the rats 2, 4, 6, and 16 weeks after the sham operation were 49.8 +/- 1.3 cm H2O, 51.2 +/- 1.5 cm H2O, 51.6 +/- 2.0 cm H2O, and 49.7 +/- 0.6 cm H2O, respectively. When compared to time-matched control groups, the decreased LPPs in each cauterized group were significantly lower (P < 0.001). Histological analysis showed muscle damage and fewer nerves in all cauterized groups. CONCLUSIONS: Cauterization of tissues lateral to the mid-urethra decreased LPP without affecting bladder function. This electrocauterization model produced low LPPs that, after 2 weeks, were maintained for up to 16 weeks. Histology suggests that damage to striated muscle and nerves might have contributed to the change in LPP in this model for ISD.     

Equine sperm nuclei with different ploidy levels: relationship between the nuclear DNA content and the nuclear area

The aims of this study were to estimate the ability of the Feulgen reaction to identify equine sperm nuclei with different ploidy levels, to determine the frequency of haploid, diploid and polyploid sperm nuclei in the semen of fertile equines and to evaluate the relationship between the nuclear DNA content and the nuclear area. Determination of the ploidy level of Feulgen-stained spermatozoa using a scanning microspectrophotometer was very similar to the subjective estimations made with a light microscope. This indicates that the Feulgen reaction is a simple, inexpensive and reliable technique to recognise the ploidy level of equine spermatozoa. The incidence of diploid and polyploid spermatozoa, determined with a light microscope in 11 fertile equines, was 0.17 ± 0.08% and 0.027 ± 0.027% respectively. DNA content values obtained by microspectrophotometry in the only equine that presented polyploid spermatozoa allowed us to discriminate between haploid, diploid and polyploid subpopulations. Measurement of the nuclear area discriminated only two subpopulations: one including the haploid and diploid subpopulations and the other including the polyploid one. The similarity between the area of the haploid and diploid sperm nuclei suggests that the increase in DNA content is anisotropic, with a privileged direction of growth perpendicular to the nuclear flattening plane.     

Embedding resin space, water contents and chromatin compaction in rabbit sperm nuclei: Electron microscopic X-ray spectrophotometry of a brominated probe

Summary.  EPON labelled with bromide was used to embed ejaculated rabbit spermatozoa, with the hypothesis that it replaces cell water. X-Ray spectrophotometric microanalysis of sperm nuclei, of egg yolk (an internal standard containing roughly 50% water) and of surrounding embedding resin, revealed that a part of the bromide was bound to the biological components. These latter were saturated when bromide was added in higher concentrations, and the increase in measured bromide could be used to calculate absolute resin contents in sperm nuclei which gives a mean value of 22.62%. Most nuclei (60.80%) were well condensed and displayed a mean resin space close to 17% of the total nuclear volume. The less condensed nuclei had a mean resin space close to 28%. The use of an internal standard revealed that calculated values were underestimated by 4%.     

哌替啶和氯胺酮对离体大鼠视上核神经元自发放电频率的影响

目的 观察静脉麻醉药氯胺酮和麻醉性镇痛药哌替啶对离体大鼠视上核（SON）神经元自发放电频率的影响。方法 将新生SD大鼠迅速断头取脑，置于通入95％O2和5％CO2混合气体的4℃人工脑脊液（ACSF）中，以振动切片机制成300—400μm含SON神经元的脑薄片，将脑薄片随机分为6组：哌替啶50μmol／L组、100μmol／L组、150μmol／L组和氯胺酮50μmol／L组、100μmol／L组、150μmol／L组，每组30张脑片，应用全细胞膜片钳记录技术观察给药前、给药后5min和正常ACSF冲洗后5min各组SON神经元自发放电频率。结果 与给药前即刻比较，3组灌流5min后、哌替啶150wnol／L组冲洗5min后SON神经元自发放电频率下降（P〈0．05或0．01）；与哌替啶50μmol／L组比较，100μmol／L组和150μmol／L组灌流5min后、冲洗5min后SON神经元自发放电频率下降（P〈0．05或0．01）。与给药前即刻比较，氯胺酮100μmol／L组和150μmol／L组灌流5min后、150μmol／L组冲洗5min后SON神经元自发放电频率下降（P〈0．05或0．01）；与氯胺酮50μmol／L组比较，氯胺酮100μmol／L组和150μmol／L组灌流5min后、150μmol／L组冲洗5min后SON神经元自发放电频率下降（P〈0．05或0．01）。结论 哌替啶和氯胺酮对大鼠SON神经元自发放电频率可产生明显可逆性的抑制作用。     

大鼠膀胱低位控制中枢的形态学研究

目的从形态学上研究膀胱交感中枢和副交感中枢之间的联系。方法通过神经追踪的方法，在SD大鼠的腹下神经和盆节给予银光金（FG），确定膀胱的交感和副交感低位控制中枢的部位，于膀胱交感控制中枢及骶副交感核（SPN）分别给予辣根过氧化物酶（HRP）和结合麦芽凝集素的辣根过氧化物酶（WGA-HRP），分别在腰6至骶1（L6-S1）和腰1至腰2（L1-L2）节段检测逆行标记细胞和顺行标记末梢，并且通过免疫组织化学的方法鉴别副交感节前神经元（乙酰胆碱转移酶阳性）和中间神经元。结果腹下神经和盆节给予FG。逆标交感节前神经元主要位于L1，L2节段的后联合核（DCN）及双侧中间侧细胞柱（IML）。副交感节前神经元位于L6，S1节段的骶副交感核（SPN）。于L1-L2节段IML区给予HRP，在SPN的背内侧发现有逆标胞体较小的非胆碱能性神经元。于SPN中电泳入WGA-HRP，在L1-L2节段的IML区发现有顺行标记的神经末梢。结论膀胱的低位交感中枢和副交感中枢之间存在有形态学上的联系，骶副交感核（SPN）背内侧组的中间神经元可能在两者之间起协调作用。     

Characterization of the intrinsic properties of the anterior cruciate and medial collateral ligament cells: an in vitro cell culture study.

The poor healing abilities of the anterior cruciate ligament (ACL) in contrast to those of the medial collateral ligament (MCL) are well known. Different intrinsic properties of the constituent cells of these ligaments have been proposed to be one of the factors in the differential repair mechanisms. To examine this hypothesis, we have established primary cell lines of ACL and MCL from the tissue explants of approximately similar dimensions and have studied their behavior in vitro. The outgrowth of cells from ACL explants was slower than from MCL explants, as shown by the size of the surrounding clusters of cells. Both ACL and MCL cultures exhibited typical fibroblastic morphology. No significant differences were observed in either attachment or growth of cells from the attached explants derived from various segments of ACL and MCL. Growth curves of ACL and MCL cultures at both passage numbers 2 and 6 showed a slower rate of proliferation of ACL cells than MCL cells (p less than 0.005). DNA synthesis measured in terms of [3H]thymidine incorporation (CPM/10(3) cells) of both log phase (ACL = 607.5 +/- 5.4 vs. MCL = 1356.4 +/- 11.3) and confluent (ACL = 83.0 +/- 3.6 vs. MCL = 189.8 +/- 5.4) cultures, supports the conclusion that differential proliferation rates of these cells exist in culture. FITC-phalloidin staining (for actin) of later passage cultures (P3-P5) showed a spread-out appearance of ACL cells and an elongated appearance of MCL cells. Relatively more stress fibers were seen within ACL cells. SDS-PAGE and Western blot analysis of cellular proteins revealed higher actin (43 kDa) content in ACL cells than in MCL cells. In vitro wound closure assay was performed by creating a uniform wound of 0.6 mm width in the confluent layer of ACL and MCL cultures. By 48 h postwounding, cell-free zones created in ACL cultures were occupied partially by single cells in a nonconfluent fashion. In contrast, the wounded zone in the MCL cultures was almost completely covered by the cells. Results presented in this report demonstrate a lower proliferation and migration potential of ACL cells in comparison with MCL cells. These differences in intrinsic properties of ACL and MCL cells that were observed in vitro might contribute to the differential healing potentials of these ligaments in vivo.     

Diagnosis and management of abscesses in the basal ganglia and thalamus: A survey

Summary A review is made of the current management strategies of abscesses in basal ganglia and thalamus, based on a review of the literature and three of our own cases. Clinical picture, aetiology, diagnostic, surgical treatment and outcome are discussed. Stereotactic abscess puncture in combination with temporary drainage and rinsing of the abscess cavity in combination with systemic medication of antibiotics has become the management of choice with satisfactory results.     

羧甲基壳聚糖对体外培养髓核细胞增殖及硝普钠诱导凋亡的影响

[目的]研究不同浓度羧甲基壳聚糖对体外培养椎间盘髓核细胞增殖及硝普钠诱导细胞凋亡的保护作用.[方法]体外培养大鼠椎间盘髓核细胞,Ⅱ型胶原免疫组化染色鉴定;分别加入不同浓度羧甲基壳聚糖培养24h,通过CCK-8细胞计数法检测髓核细胞的增殖情况;采用不同浓度硝普钠诱导髓核细胞凋亡,通过流式细胞仪检测早期凋亡细胞比例,并通过Hoechst 33342荧光染色检测髓核细胞凋亡核的形态学变化.[结果]CCK-8检测结果表明10～500μg/ml羧甲基壳聚糖作用髓核细胞24 h对髓核细胞增殖无明显作用(P＞0.05);流式细胞检测结果表明1～3mmol/L的硝普钠可诱导髓核细胞发生早期凋亡,加入50～200μg/ml羧甲基壳聚糖后硝普钠诱导的髓核细胞凋亡有不同程度的降低(P＜0.05).Hoechst 33342染色结果表明羧甲基壳聚糖可降低硝普钠诱导髓核细胞凋亡.[结论]一定浓度的羧甲基壳聚糖对髓核细胞增殖无明显影响,羧甲基壳聚糖对硝普钠诱导下髓核细胞凋亡有保护作用.     

Functional diversity of layer IV spiny neurons in rat somatosensory cortex: quantitative morphology of electrophysiologically characterized and biocytin labeled cells

Previous analyses of the spiny layer IV neurons have almost exclusively focused on spiny stellate cells. Here we provide detailed morphological data characterizing three subpopulations of spiny neurons in slices of adolescent rats: (i) spiny stellate cells (58%), (ii) star pyramidal cells (25%) and (iii) pyramidal cells (17%), which can be distinguished objectively by the preferential orientation of their dendritic stems. Spiny stellate cells lacked an apical dendrite and frequently confined their dendritic and axonal arbors to the respective column. Star pyramidal and pyramidal cells possessed an apical dendrite, which reached the supragranular layers. Their axonal arbors were similar, showing both a columnar component and transcolumnar branches with direct transbarrel projections. However, a small fraction of star pyramidal cells possessed few or even no transcolumnar branches. Electrophysiologically, all three types of neurons were either regular-spiking or intrinsically burst-spiking without a significant relation to the morphological subtypes. The basic synaptic properties of thalamic inputs were also independent of the type of target layer IV spiny neuron. All remained subthreshold and showed paired-pulse depression. In conclusion, the columnar axonal arborization of spiny stellate cells is supplemented by a significant oblique to horizontal projection pattern in pyramidal-like neurons. This offers a structural basis for either segregation or early context-dependent integration of tactile information, in a cell-type specific manner.     

Chronic compression model of the cauda equina: Histological and electrophysiological study

Histological and electrophysiological changes of the cauda equina caused by chronic compression with silicone film were assessed in the lumbar spine of adult cats. Twenty cats underwent laminectomy of the sixth lumbar vertebra. The animals were divided into four groups (n=5 each). In three groups, the dura was covered with silicone film. The fourth group (sham-operated) served as controls. Histological and electrophysiological studies, using spinal cord evoked potentials (SpEPs) with high frequency stimulation (HFS) were performed after periods of 4, 12, and 24 weeks. Controls were examined at 12 weeks. Dilatation of the endoneurial microvessels was noted in two of five cats in the 4-week group and in all animals in the 12- and 24-week groups. The nerve fibers of the control animals and the naimals in the 4-week group were normal. In the 12-week group, a decrease in the number of large myelinated fibers and an increase in the number of small myelinated fibers was seen in the dorsal and ventral nerve roots. Electrophysiologically, there was no significant difference in SpEPs before and after the silicone film coverage. Recovery of the peak latency was significantly delayed after HFS in the 24-week group. This model is considered to be useful in studying the pathophysiology of chronically compressed cauda equina.     

Determination of diffusion and partition coefficients of propofol in rat brain tissue: implications for studies of drug action in vitro

Background. Propofol (2,6-diisopropylphenol) is a widely usedgeneral anaesthetic that modulates     

Comparison of the urethral properties of the female guinea pig and rat

AIMS: The main focus of this study was to profile and compare urethral function in the female guinea pig and rat, and to characterize urodynamically distinctive patterns in the micturition cycle of the two species. This exercise aimed to investigate potential species-related differences and determine a suitable animal model for the human urethra. MATERIALS & METHODS: Female Dunkin-Hartley guinea pigs (400-500 g) and Sprague-Dawley rats (200-300 g) were used throughout the study. For in vitro experiments urethral rings were suspended vertically for isometric tension recording in 5 ml organ baths and drugs (phenylephrine 10(-4) M and carbachol 10(-4) M) were applied directly to the bathing solution. In vivo urethral pull-through and urodynamic studies were performed under urethane anesthesia, and phenylephrine (200 microg/kg) was administered during urethral pull-through experiments via the intravenous (i.v.) route. Urethral, bladder and arterial pressures, and external urethral sphincter electromyographic (EMG) spike activity were recorded simultaneously throughout. RESULTS: Organ bath studies coupled with in vivo pull-through experiments produced urethral profiles with distinct regional variations for both species. Urodynamic studies with the urethral probe fixed in the high pressure zones of the proximal urethra produced similar recordings in both species during bladder filling and marked differences during micturition. The guinea pig showed complete sphincteric inhibition immediately prior and during micturition as also seen in the human, whereas the rat exhibited high frequency bursts in EMG activity at this stage in the cycle. CONCLUSIONS: The EMG activity seen in the rat during micturition is presumably necessary for efficient voiding, thus the guinea pig is a more suitable comparative model for the human in relation to urethral properties during micturition.     

Induced hypertension during restoration of flow after temporary middle cerebral artery occlusion in the rat: effect on neuronal injury and edema

The effect of hypertension instituted during restoration of flow after focal ischemia was studied. After the middle cerebral artery (MCA) of 12 rats was occluded for 2 hours, the ligatures were released and flow was restored for a period of 2 hours. In the control group, mean arterial pressure (MAP) was not manipulated. In the hypertensive group, the MAP was elevated by 25-30 mm Hg immediately after reestablishment of MCA patency. The area of neuronal injury, determined by 2,3,5-triphenyltetrazolium staining, was significantly smaller in the hypertensive group. Specific gravity, determined by microgravimetry, did not differ between groups. The data demonstrate that modest hypertension, when induced during reperfusion after 2 hours of MCA occlusion, reduces neuronal injury and does not exacerbate edema formation.     

Small intestinal transplantation in the rat: effect on physiological properties of smooth muscle and nerves

The effect of transplantation on the physiological and pharmacologic properties of small intestine was evaluated in a syngeneic rat model. We examined the intrinsic contractile properties of the smooth muscle, the neural control of intestinal motility, and the sensitivity of the muscle and nerve endings to biologically active compounds in vitro, comparing transplanted tissue to controls. Both graft and control tissue contracted in a dose-dependent manner to cholinergic agonists, 5-hydroxytryptamine, and substance P and relaxed in response to noradrenaline. Contractile properties of smooth muscle and sensitivity to drugs were not altered by transplantation. Excitatory innervation was also similar in all specimens, but the inhibitory response was altered by transplantation. In the control intestine inhibition became maximal above 30 Hz, while in the graft maximal inhibition was obtained at 5 Hz. These findings imply an absence of extrinsic adrenergic inhibitory innervation in the graft. Intrinsic nonadrenergic inhibitory nerves and the excitatory innervation were intact after transplantation.     

Bladder acellular matrix graft: in vivo functional properties of the regenerated rat bladder

The purpose of this study was to determine whether the rat urinary bladder augmented by an acellular matrix graft can restore the bladder's low-pressure reservoir function and preserve normal micturition. After partial cystectomy (>50%) and grafting with the bladder acellular matrix graft (BAMG), storage and voiding functions were monitored in 20 rats by means of a specially designed “micturition cage,” leak-point cystography, and cystometry. After 4 months, sections (n = 6) were examined histologically to evaluate regeneration of bladder wall components within the BAMG. Bladder capacity and compliance increased progressively and were significantly higher in the grafted animals than in controls (partial cystectomy only), and volumes per void were significantly higher than in either control or normal animals. At 4 months, the regenerated urothelium, smooth muscle, blood vessels and nerves within the BAMG were qualitatively identical to normal bladder wall. Augmentation cystoplasty with the homologous BAMG leads to morphologic and functional rat bladder regeneration, thus enhancing low-pressure reservoir function and preserving normal micturition. Received: 27 May 1998 / Accepted: 20 October 1998