bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Thalamocortical Synaptic Transmission across Awake Brain States
Authors: Stoelzel Carl R. , Bereshpolova Yulia , Swadlow Harvey A.
Published: May 2009

Sensory cortical neurons are highly sensitive to brain state, with many neurons showing changes in spatial and/or temporal response properties and some neurons becoming virtually unresponsive when subjects are not alert. Although some of these changes are undoubtedly attributable to state-related filtering at the thalamic level, another likely source of such effects is the thalamocortical (TC) synapse, where activation of nicotinic receptors on TC terminals have been shown to enhance synaptic transmissionin vitro. However, monosynaptic TC synaptic transmission has not been directly examined during different states of alertness. Here, in awake rabbits that shifted between alert and non-alert EEG states, we examined the monosynaptic TC responses and short-term synaptic dynamics generated by spontaneous impulses of single visual and somatosensory TC neurons. We did this using spike-triggered current source-density analysis, an approach that enables assessment of monosynaptic extracellular currents generated in different cortical layers by impulses of single TC afferents. Spontaneous firing rates of TC neurons were higher, and burst rates were much lower in the alert state. However, we found no state-related changes in the amplitude of monosynaptic TC responses when TC spikes with similar preceding interspike interval were compared. Moreover, the relationship between the preceding interspike interval of the TC spike and postsynaptic response amplitude was not influenced by state. These data indicate that TC synaptic transmission and dynamics are highly conserved across different states of alertness and that observed state-related changes in receptive field properties that occur at the cortical level result from other mechanisms.
Hindbrain Cocaine- and Amphetamine-Regulated Transcript Induces Hypothermia Mediated by GLP-1 Receptors
Authors: Skibicka Karolina P. , Alhadeff Amber L. , Grill Harvey J.
Published: May 2009

Cocaine- and amphetamine-regulated transcript (CART) peptides are widely distributed throughout the neuraxis, including regions associated with energy balance. CART's classification as a catabolic neuropeptide is based on its inhibitory effects on feeding, coexpression with arcuate nucleus proopiomelanocortin neurons, and on limited analysis of its energy expenditure effects. Here, we investigate whether (1) caudal brainstem delivery of CART produces energetic, cardiovascular, and glycemic effects, (2) forebrain–caudal brainstem neural communication is required for those effects, and (3) glucagon-like peptide-1 receptors (GLP-1Rs) contribute to the mediation of CART-induced effects. Core temperature (Tc), heart rate (HR), activity, and blood glucose were measured in rats injected fourth intracerebroventricularly with CART (0.1, 1.0, and 2.0 μg). Food was withheld during physiologic recording and returned for overnight measurement of intake and body weight. CART induced a long-lasting (>6 h) hypothermia: a 1.5°C and 1.6°C drop in Tc for the 1.0 and 2.0 μg doses. Hindbrain CART application reduced food intake and body weight and increased blood glucose levels; no change in HR or activity was observed. Supracollicular decerebration eliminated the hypothermic response observed in intact rats to hindbrain ventricular CART, suggesting that forebrain processing is required for hypothermia. Pretreatment with the GLP-1R antagonist (exendin-9–39) in control rats attenuated CART hypothermia and hypophagia, indicating that GLP-1R activation contributes to hypothermic and hypophagic effects of hindbrain CART, whereas CART-induced hyperglycemia was not altered by GLP-1R blockade. Data reveal a novel function of CART in temperature regulation and open possibilities for future studies on the clinical potential of the hypothermic effect.
Regulation of vascular growth and function in the human placenta
Authors: Burton G J , Charnock-Jones D S , Jauniaux E
Published: May 2009

During the course of 9 months, the human placenta develops into a highly vascular organ. Vasculogenesis starts during the third week post-conception. Hemangioblastic cell cords differentiatein situfrom mesenchymal cells in the villous cores, most probably under the influence of vascular endothelial growth factor (VEGFA) secreted by the overlying trophoblast. The cords elongate through proliferation and cell recruitment, and connect with the vasculature of the developing fetus. A feto-placental circulation starts around 8 weeks of gestation. Elongation of the capillaries outstrips that of the containing villi, leading to looping of the vessels. The obtrusion of both capillary loops and new sprouts results in the formation of terminal villi. Branching and non-branching angiogenesis therefore play key roles in villous morphogenesis throughout pregnancy. Maternal circulating levels of VEGFA and placental growth factor vary across normal pregnancy, and in complicated pregnancies. Determining the impact of these changes on placental angiogenesis is difficult, as the relationship between levels of factors in the maternal circulation and their effects on fetal vessels within the placenta remains unclear. Furthermore, the trophoblast secretes large quantities of soluble receptors capable of binding both growth factors, influencing their bioavailability. Villous endothelial cells are prone to oxidative stress, which activates the apoptotic cascade. Oxidative stress associated with onset of the maternal circulation, and with incomplete conversion of the spiral arteries in pathological pregnancies, plays an important role in sculpting the villous tree. Suppression of placental angiogenesis results in impoverished development of the placenta, leading ultimately to fetal growth restriction.
Properties of high yield synthesised carbon nano fibres/Portland cement composite
Authors: Cwirzen A. , Habermehl-Cwirzen K. , Shandakov D. , Nasibulina L.I. , Nasibulin A.G. , Mudimela P.R. , Kauppinen E.I. , Penttala V.
Published: May 2009

The compressive strength and electrical resistivity of hardened pastes produced either from nanomodified Portland sulfate-resistant cement (CHH) or a mixture of nanomodified and pristine sulfate-resistant cements were determined. The nanomodification included grow carbon nanotubes (CNTs) and carbon nanofibres (CNFs) on the cement particles. Pastes having a water-to-binder ratio of 0·5 were produced. The test results revealed that partial replacement of sulfate-resistant cement by CHH cement decreased the electrical resistivity of the 28 day old specimens but worsened the mechanical properties. The lower compressive strength was attributed to a lower degree of hydration of the CHH cement. The addition of a mixture of surfactants enabled the production of specimens consisting entirely of CHH cement. The hardened material obtained was characterised by a nearly doubled compressive strength in comparison with the reference specimens made from pristine sulfate-resistant cement. This was attributed to a high degree of hydration as well as reinforcing action of the CNTs and CNFs. The electrical resistivity was lowered by one order of magnitude classifying this material as a semiconductor.
Fluidic Oscillation Technique in Conjunction with Acid Stimulation Improves Gas Wells Productivity
Authors: Hegazy Ahmed , Conrad Bruce , Waheed Arshad , Sanad Osama
Published: May 2009

Generally, the most common reason for low productivity of gas wells in the offshore Mediterranean Sea operations of Egypt is near-wellbore formation damage. Near-wellbore formation damage, referred to as "skin" in petroleum engineering parlance, causes a huge reduction in native formation permeability, thus adversely affecting productivity. Skin damage can occur from one or more of the following reasons: mud and cement damage, mechanical damage from drilling, damage from perforating guns, scale deposition, paraffin and asphaltene depositions, water blocks, gas blocks, acid sludges, emulsions, etc. Dependent upon the type of damage, the stimulation technique will vary; however, the prevalent techniques available to stimulate damaged formations are hydraulic fracturing and matrix acid stimulation.

A new technique called "fluidic oscillation" was proposed to overcome many of the limitations of the previous two techniques. This technique would be especially applicable when there are uncertainties regarding rock mineralogy. In these instances the possibility of further damage exists if incompatible treatment fluids are pumped/"squeezed" into the formations. "Fluidic Oscillation" is primarily a mechanical, nonfluid invasive stimulation technique; (i.e., it is not essential to inject the treatment fluid into the reservoir to break down damage though it does not preclude its use in that manner). The damaged formations are stimulated by subjecting them to alternating bursts of pressure waves generated by pumping fluids through a fluidic oscillator. The treatment fluid can be plain water, diesel, or any other solvent that is desired to pass through the affected zones and be circulated out of the hole. The continuous cycling of these pressure waves causes the skin damage to reach its fatigue failure point. After this, a small amount of acid/solvent blend can be pumped to wash the damaging materials out of the well bore. The fluidic oscillator can be positioned against the zones of interest by using coiled tubing.

The fluidic oscillation technique was used in Egypt on two gas wells (until the writing of this paper) for this operator. In the first well, it is believed that there was heavy formation damage caused while drilling the well. After the stimulation treatment the gas production of the well was increased by 325%. In the second well, the post-stimulation gas production rate was increased by 40%. From IPR curves of the two wells, before and after stimulation, it was found that the absolute open flow (AOF) potential of each well was highly increased after stimulation. Compared to the results obtained from previous treatments, it was found that this technique was successful in stimulating gas wells in Egypt. The main objective of this paper is to evaluate this technique through actual case studies.
Objectively Measured Sedentary Time May Predict Insulin Resistance Independent of Moderate- and Vigorous-Intensity Physical Activity
Authors: Helmerhorst Hendrik J.F. , Wijndaele Katrien , Brage Søren , Wareham Nicholas J. , Ekelund Ulf
Published: May 2009

OBJECTIVE

To examine the prospective association between objectively measured time spent sedentary and insulin resistance and whether this association is independent of moderate- and vigorous-intensity physical activity (MVPA) and other relevant confounders.

RESEARCH DESIGN AND METHODS

This was a population-based study (Medical Research Council Ely study) in 376 middle-aged adults (166 men; 210 women) over 5.6 years of follow-up. Physical activity and sedentary time were measured objectively by individually calibrated minute-by-minute heart rate monitoring at both baseline and follow-up. Sedentary time was calculated as the heart rate observations (in minutes) below an individually predetermined threshold (flex heart rate) and expressed as a percentage of total monitored time during waking hours over 4 days. The percentage of time spent above 1.75 × resting heart rate represented MVPA. Fasting plasma insulin was used as a surrogate measure of insulin resistance.

RESULTS

Time spent sedentary at baseline was significantly and positively associated with log fasting insulin at follow-up (β = 0.003, 95% CI 0.0006–0.006, P = 0.015) independent of baseline age, sex, fat mass, fasting insulin, smoking status, and follow-up time. After further adjustment for MVPA, this association was somewhat strengthened (β = 0.004, 95% CI 0.0009–0.006, P = 0.009).

CONCLUSIONS

Time spent sedentary predicts higher levels of fasting insulin independent of the amount of time spent at moderate- and vigorous-intensity activity levels. This highlights the importance of reducing sedentary time in order to improve metabolic health, possibly in addition to the benefits associated with a physically active lifestyle.
The neuroprotective pharmacology of methylprednisolone
Authors: Hall Edward D.
Published: May 2009

✓ A 24-hour intensive intravenous dosing regimen with the glucocorticoid steroid methylprednisolone has recently been shown to be effective in enhancing neurological recovery in spinal cord-injured patients when initiated within 8 hours after injury. The state of knowledge concerning the neuroprotective pharmacology of methylprednisolone, including mechanism(s) of action, dosing requirements, and time-action considerations is reviewed, as are the results of studies with high doses in experimental and clinical head injury, subarachnoid hemorrhage, and cerebral ischemia. A primary neuroprotective mechanism of action in each of these cases is hypothesized to involve the ability of high doses of methylprednisolone to inhibit oxygen free radical-induced lipid peroxidation, although additional mechanisms may contribute. Unresolved issues are also addressed, including the therapeutic window, optimum duration of treatment, and rational combination with other neuroprotective agents. A newer methylprednisolone pro-drug with improved solution stability is discussed, together with a brief consideration of novel nonglucocorticoid steroids that surpass methylprednisolone's lipid antioxidant effects without unwanted glucocorticoid properties.
Cytoskeletal and extracellular matrix proteins in cerebral arteries following subarachnoid hemorrhage in monkeys
Authors: Macdonald R. Loch , Weir Bryce K. A. , Young James D. , Grace Michael G. A.
Published: May 2009

✓ It is unclear if vasospasm after subarachnoid hemorrhage (SAH) is predominantly due to smooth-muscle contraction, proliferative vasculopathy, or other changes within the arterial wall such as fibrosis or change in smooth-muscle phenotype. In this study, immunohistochemistry was used to examine changes in extracellular and cytoskeletal proteins in cerebral arteries after SAH that might support one of these mechanisms. Following baseline cerebral angiography, bilateral SAH was created in nine monkeys. Three animals each were killed 7, 14, or 28 days after SAH. Cerebral angiography was repeated on Day 7 in all animals and immediately prior to sacrifice in animals killed on Days 14 and 28. Both middle cerebral arteries and four control basilar arteries were examined using fluorescent antibody techniques with antisera to α-actin, myosin, fibronectin, fibrinogen, vimentin, desmin, laminin, and collagens (types I, III, IV, and V).

Angiography showed that vasospasm was most severe on Day 7, present but resolving on Day 14, and completely resolved by Day 28. Microscopic study of arterial sections and blinded review of microphotographs of arterial sections by five independent observers did not reveal changes in intensity of density of staining for collagens, desmin, myosin, laminin, or α-actin in the tunica media of tunica adventitia. Fibronectin immunoreactivity increased 14 days after SAH. Seven days after SAH, occasional areas of tunica media showed immunoreactivity to fibrinogen. On Day 28, intimal thickening was observed in four of six middle cerebral arteries and this tissue demonstrated immunoreactivity to α-actin, myosin, vimentin, desmin, fibronectin, laminin, and each type of collagen. No significant increases in the number of intimal cells showing immunoreactivity to α-actin were seen and no significant changes in the hydroxyproline content of cerebral arteries developed at any time after SAH. These results suggest that rigidity and lumen narrowing of vasospasm are not due to increased arterial collagen, although other proteins in the arterial wall or an alteration in cross-linking of existing proteins could produce these changes. There is no indication that smooth-muscle contractile proteins change during vasospasm or that increases in the number of α-actin-containing myointimal cells contribute to vasospasm. The occurrence of intimal thickening and increased tunica media fibronectin after vasospasm suggests that vasospasm damages smooth muscle, possibly as a result of intense prolonged smooth-muscle contraction.
Effects of inhibitors of protein kinase C and calpain in experimental delayed cerebral vasospasm
Authors: Minami Nobutaka , Tani Eiichi , Maeda Yukio , Yamaura Ikuya , Fukami Masahiro
Published: May 2009

✓ Vasospasm was produced in adult mongrel dogs by a two-hemorrhage method, and the spastic basilar arteries were exposed via the transclival route on Day 7. Tonic contraction was produced in the normal canine basilar arteries by a local application of KCl or serotonin after transclival exposure. The exposed spastic and tonic basilar arteries then received a topical application of the following: 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine (H-7), a potent inhibitor of protein kinase C acting at the catalytic domain; calphostin C, a specific inhibitor of protein kinase C acting at the regulatory domain; or calpeptin, a selective inhibitor of calpain. Both spastic and tonic basilar arteries were effectively dilated by H-7. Calphostin C caused only slight dilation of spastic basilar arteries but moderate dilation of tonic basilar arteries. Dilation in response to calpeptin was remarkable in the spastic basilar arteries but slight in the tonic basilar arteries. The doses of calphostin C and calpeptin required to obtain maximum effect were markedly lower in the tonic model than in the spastic model. The spastic and tonic models had a similar dose-dependent response to H-7 but quite a different response to calphostin C or calpeptin, suggesting a difference in the function of protein kinase C and calpain in the two models. Furthermore, the effect of calphostin C on the reversal of vasospasm was increased significantly after topical treatment with calpeptin. It is suggested that the majority of the catalytic domain of protein kinase C is dissociated from the regulatory domain, probably by a limited proteolysis with calpain, and is markedly activated in vasospasm.
The symptomatic and functional outcome of stereotactic thalamotomy for medically intractable essential tremor
Authors: Goldman Marc S. , Ahlskog J. Eric , Kelly Patrick J.
Published: May 2009

✓ Eight patients with medically refractory disabling essential tremor underwent ventralis lateralis (VL) thalamotomies; the procedure was unilateral in seven cases and bilateral (staged) in the other. Contralateral tremor remained absent or markedly reduced in all patients at the time of the most recent follow-up examinations, at a mean of 17.3 months after surgery. Disability was determined by a modified form of an established rating scale for tremor, and was reduced from a mean score of 21.1 (moderate grade) to 3.9 (absent grade) (p < 0.001). Interestingly, voice tremor was abolished or significantly improved in 71.4% of patients with preoperative voice tremor. This feature has not been reported previously. Persistent surgical morbidity was limited to two patients with mild dysarthria and one with a mild cognitive impairment. There were no surgically related deaths. It is concluded that stereotactic VL thalamotomy is a treatment option for medically intractable disabling essential tremor.
Neurovascular compression in trigeminal neuralgia: a clinical and anatomical study
Authors: Hamlyn Peter J. , King Thomas T.
Published: May 2009

✓ Neurovascular decompression is a widely practiced tec hnique for the treatment of trigeminal neuralgia, and yet there is still debate as to whether the beneficial effect results from relieving the nerve of compression by an anatomically abnormal vessel or from the manipulation and trauma the nerve undergoes during the procedure. The development of this operation has been hampered by the lack of adequate anatomical studies in normal controls. The authors present a combined study of clinical and anatomical material employing standardized definitions of the neurovascular relationships in both groups. Detailed simulations of the operative procedure were carried out on fresh cadavers matched for age, sex, and side, and a technique of in situ blood vessel perfusion was developed that enabled the normal neurovascular arrangement to be observed post mortem at physiological pressures.

Neurovascular compression, typified by a large vessel distorting and creating a groove in the fifth cranial nerve, was found in 37 of the 41 cases of trigeminal neuralgia; recurrence of pain did not relate to the site of compression. A follow-up study was carried out for a median of 53 months (range 12 to 103 months). No distortion was found in a total of 50 normal cadaveric dissections; however, on perfusion to physiological pressures, the percentage of nerves with vessels adjacent or in simple contact increased from 16% to 40%. This study using this new technique confirms that vascular compression of the fifth cranial nerve is an anatomical abnormality specific to trigeminal neuralgia.
Sensitivity of human glioma and brain cells to natural killer cell lysis
Authors: Myers Rene L. , Whisler Ronald L. , Stephens Ralph E. , Sponseller Craig A. , Livingston Kimberly , Spring Paul M. , Yates Allan J.
Published: May 2009

✓ Using an in vitro monolayer natural killer (NK) cytolysis assay, the authors examined the effects of serum concentration and epidermal growth factor (EGF) on sensitivity to NK cytolysis. It was found that target cells cultured in high concentrations of serum (10% fetal bovine serum (FBS)) had higher cytotoxicity levels than those in low serum concentrations (0% to 0.5% FBS). Exposure of target cells to EGF had no effect on their sensitivity to NK cytolysis. Both glioma cell lines showed decreased NK cell sensitivity with longer times in culture. The results of cytofluorometric studies on these cell lines indicate that the differences in NK cell sensitivity may reflect the growth fraction of the target population and that a population with a higher proportion of cycling cells is more susceptible to lysis by NK cells. Whether it is possible to separate the proliferative rate of these cells from their NK cell sensitivity is unknown, but worthy of consideration.
High-energy phosphate levels in the cerebral artery during chronic vasospasm after subarachnoid hemorrhage
Authors: Kim Phyo , Jones James D. , Sundt Thoralf M.
Published: May 2009

✓ High-energy phosphate levels were measured in the canine cerebral artery during chronic vasospasm. Subarachnoid hemorrhage and vasospasm were induced by percutaneous injections of autologous venous blood into the cisterna magna. Narrowing of the artery was confirmed by angiography 7 days later. Levels of adenosine phosphates (adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP)), guanosine phosphates (guanosine triphosphate (GTP) and guanosine diphosphate (GDP)), and creatine phosphate (CrP) in the basilar artery were quantified using high-performance liquid chromatography. The total creatine (Crtotal) content was measured by a spectrophotometric method after acid hydrolysis of CrP. Levels of ATP, GTP, and CrP were markedly reduced in the spastic arteries, and ratios of ATP:ADP, GTP:GDP, and CrP:Crtotal were significantly decreased. The results indicate a serious disturbance in the energy metabolism that takes place in the cerebral artery during chronic vasospasm.
Interphase cytogenetics: a new tool for the study of genetic changes in brain tumors
Authors: Arnoldus Edo P. J. , Wolters Laetitia B. T. , Voormolen Joan H. C. , van Duinen Sjoerd G. , Raap Anton K. , van der Ploeg Mels , Peters A. C. Boudewijn
Published: May 2009

✓ Interphase cytogenetics is the application of nonradioactive in situ hybridization with chromosome-specific DNA probes to interphase nuclei. In this study, interphase cytogenetics was used to investigate 66 primary brain tumors (33 gliomas, 30 meningiomas, and three medulloblastomas) for numerical chromosomal aberrations of chromosomes 1, 6, 7, 10, 11, 17, 18, X, and Y.

Of the 33 gliomas (17 astrocytomas grades II, III, and IV, five oligoastrocytomas, seven oligodendrogliomas, and four ependymal tumors), 22 were near diploid, while the remaining 11 showed a significant triploid or tetraploid component. The predominant specific aberrations in gliomas were an over-representation of chromosome 7 (13 cases) and an under-representation of chromosome 10 (16 cases), These changes were observed in grade III and grade IV astrocytomas, as well as in oligodendrogliomas. Other frequent numerical changes were a gain of chromosome 17 (six cases) and a loss of chromosome 18 (seven cases). This loss of chromosome 18 seemed relatively specific for gliomas with an oligodendroglial component (six cases). Only two of 33 gliomas displayed no genetic abnormality with the probes used. Seven patients with astrocytomas died of their brain tumor during the clinical follow-up period. Their astrocytomas did not show a different chromosomal constitution compared to the other gliomas.

For the meningiomas, the probe panel was extended with a probe specific for chromosome 22. Loss of chromosome 22 was obvious in 21 of the 30 meningiomas, and was the sole abnormality in 11 meningiomas; in the other 10, this loss was associated with other chromosomal changes. Five of these tumors with additional aberrations were recurrent or atypical meningiomas.

It is suggested that interphase cytogenetics can contribute to a better understanding of the biological behavior of these tumors and possibly result in better insights into prognosis and strategies for therapy.
Diagnosis and treatment of Ogilvie's syndrome after lumbar spinal surgery
Authors: Feldman Robert A. , Karl Richard C.
Published: May 2009

✓ Three patients who developed Ogilvie's syndrome following lumbar spinal surgery are described. Ogilvie's syndrome, also known as pseudo-obstruction of the colon, is characterized by massive cecal distention without mechanical obstruction. If this condition is not recognized and not promptly treated, it may be complicated by cecal perforation, a life-threatening hazard. The etiology, diagnosis, management, and potential relationship between lumbar spinal surgery and Ogilvie's syndrome are discussed.
Apnea testing for the determination of brain death: a modified protocol
Authors: Benzel Edward C. , Mashburn Jay P. , Conrad Steven , Modling Denise
Published: May 2009

✓ The absence of spontaneous respirations at a PaCO2 of 60 mm Hg or above has traditionally been accepted as the respiratory criteria for the determination of brain death. The testing of patients for the presence or absence of apnea has been complicated because the rate of PaCO2 elevation may vary substantially from patient to patient, and a nonlinear relationship exists between the rate of PaCO2 increase and the duration of apnea.

In an attempt to refine the apnea test and to further elucidate the physiology of hypercapnia in humans, 11 patients who met all but the respiratory criteria for brain death were evaluated using a modification of a previously utilized apnea testing protocol. All patients were brought to a PaCO2 of 40 mm Hg or above prior to the apnea test. Baseline PaCO2 ranged from 40 to 45 mm Hg in six patients (Group I) and from 46 to 51 mm Hg in five patients (Group II). The mean rate of PaCO2 increase was 5.1 ± 1.4 mm Hg/min in Group I and 6.7 ± 3.1 mm Hg/min in Group II. No problems with cardiovascular instability or hypoxia were encountered during testing in this series. This refinement of the apnea test allows for a streamlined and safe approach to brain death detection.
Risk factors predicting operable intracranial hematomas in head injury
Authors: Gutman Michael B. , Moulton Richard J. , Sullivan Irene , Hotz Gillian , Tucker William S. , Muller Paul J.
Published: May 2009

✓ A study was performed to examine the incidence of operable traumatic intracranial hematomas accompanying head injuries of differing degrees of severity, and to see if factors predicting operable mass lesions could be identified. Logistic analysis was used to identify independent predictors of operable traumatic intracranial hematomas.

Data were gathered prospectively on 1039 patients admitted with head injury between January, 1986, and December, 1990. Patient age, Glasgow Coma Scale (GCS) score, pupillary inequality, and injury by falling were all independent predictors of the presence of operable intracranial hematomas (p = 0.0000, 0.0000, 0.0182, and 0.0001, respectively). Injury to vehicle occupants was less likely to result in operable mass lesions (p = 0.0001) than injury by other means. The incidence of traumatic intracranial hematomas in patients over 50 years old was three to four times higher than in those under 30 years of age. Not surprisingly, the incidence of operable hematomas increased with decreasing GCS scores. However, even at a GCS score of 13 to 15, patients with other risk factors had a substantial incidence of operable mass lesions. There was a 29% incidence of operable intracranial hematomas for patients with a GCS score of 13 to 15, aged over 40 years and injured in a fall.

It is suggested that patients who are middle-aged or older, or those injured in falls, are at particular risk for traumatic intracranial hematomas even if their GCS score is high. These patients should have early definitive investigation with computerized tomography in order to identify operable hematomas and to initiate surgical treatment prior to neurological deterioration from mass effect.
Arterial hypertension and neurovascular compression at the ventrolateral medulla
Authors: Naraghi Ramin , Gaab Michael R. , Walter Gerhard F. , Kleineberg Berthold
Published: May 2009

✓ Intraoperative observations and animal experiments suggest that neurovascular compression at the left ventrolateral medulla is a possible etiological factor in essential hypertension. In pursuing this hypothesis, the authors examined the neurovascular relations in the posterior cranial fossa of 24 patients with essential hypertension, of 10 with renal hypertension, and of 21 normotensive control patients. Artificial perfusion of the vessels and microsurgical investigations during autopsy identified the vascular relations at the brain stem and at the root entry zone of the caudal cranial nerves. There was no evidence of neurovascular compression at the ventrolateral medulla on the left side in any patient from the control group or among those with renal hypertension. Two normotensive patients had neurovascular compression at the right ventrolateral medulla by the posterior inferior cerebellar artery. In contrast, all patients with essential hypertension had definite neurovascular compression at the left ventrolateral medulla. Additional compression of the right side was seen in three of these patients. Based on the anatomical appearance, it was possible to define three distinct types of neurovascular compression at the ventrolateral medulla. Common to all three types is the compression of the medulla oblongata at its rostral part just caudal to the pontomedullary junction and lateral to the olive in the retro-olivary sulcus.

Comparative histopathological study of the microsurgically examined brain-stem specimens revealed no differences between patients with essential hypertension, those with renal hypertension, and normal controls. There was a structural integrity at the site of neurovascular compression at the ventrolateral medulla. The microanatomical findings of this study show that neurovascular relations at the ventrolateral medulla in essential hypertension give rise to pulsatile compression on the left. This supports Jannetta's hypothesis of neurovascular compression at the left ventrolateral medulla as an etiology of essential hypertension.
Occlusion of the pig superior sagittal sinus, bridging and cortical veins: multistep evolution of sinus-vein thrombosis
Authors: Fries Georg , Wallenfang Thomas , Hennen Johannes , Velthaus Markus , Heimann Axel , Schild Hans , Perneczky Axel , Kempski Oliver
Published: May 2009

✓ Cerebral sinus-vein thrombosis may lead to severe hemodynamic changes, elevated intracranial pressure (ICP), and brain edema. It is supposed that progression of the thrombus from the sinus into bridging and cortical veins plays a key role in the development of these pathophysiological changes, but this hypothesis lacks experimental proof. The aim of this study, using a novel animal model of sinus-vein thrombosis, was to evaluate the effects of a standardized occlusion of the superior sagittal sinus and its bridging and cortical veins on hemodynamic alterations, on brain water content, and on ICP in domestic pigs.

In 10 animals, the middle third of the superior sagittal sinus was occluded with a catheter-guided balloon. Five of these pigs received an additional injection of 1 ml fibrin glue into the superior sagittal sinus anterior to the inflated balloon, leading to an obstruction of bridging and cortical veins. In five control animals the balloon was inserted but not inflated. Five pigs underwent cerebral angiography. Four hours after occlusion, the brains were frozen in liquid nitrogen, and coronal slices were examined for Evans blue dye extravasation, regional water content, and histological changes.

Occlusion of the superior sagittal sinus alone did not affect ICP or cerebral perfusion pressure (CPP). The additional injection of fibrin glue caused an obstruction of cortical and bridging veins as well as severe increases in mean (± standard deviation) ICP to 49.4 ± 14.3 mm Hg, compared with 8.3 ± 4.5 mm Hg in sham-treated controls and 7.1 ± 3.9 mm Hg in animals with occlusion of the superior sagittal sinus alone. There was also a steep fall in the mean CPP to 34.2 ± 19.6 mm Hg compared with 96.4 ± 13.8 mm Hg in the control group.

White-matter water content anterior to the occlusion site was elevated to 81.9 ± 3.7 gm/100 gm frozen weight in the fibrin group as compared to 70.7 ± 2.2 gm/100 gm in controls. Posterior to the occlusion site, water content did not differ among the three groups. Angiography demonstrated collateral flow via cortical and bridging veins in animals with occlusion of the superior sagittal sinus alone. Additional fibrin glue obstructed these collateral vessels.

The data suggest a multistep process of pathophysiological alterations in patients with sinus-vein thrombosis and may explain why these patients present with a wide variety of symptoms: minor neurological deficits or headache might indicate thrombosis of the superior sagittal sinus and/or its bridging veins. In subjects with severe symptoms, coma, and increased ICP there may be an additional involvement of tributary cortical veins. The proposed multistep process offers the rationale for heparin treatment of sinus-vein thrombosis even in patients with minor symptoms.
Serum proteolytic activity during the growth of C6 astrocytoma
Authors: Vaithilingam Indrasen S. , McDonald Warren , Brown Noel K. , Stroude Eric , Cook Robert A. , Del Maestro Rolando F.
Published: May 2009

✓ Tumor growth is dependent on the ability of neoplastic cells to induce angiogenesis. Blood-vessel remodeling requires the reconstruction of the nonfibrous proteins and type IV collagen components of the basement membrane. This study has assessed the influence of the growth of C6 astrocytoma cells in the rat spheroid implantation model on serum general protease and type IV collagenase activity. The results demonstrate that general protease activity increased in serum, reaching maximum values on Day 6 and Day 13 following spheroid implantation, and that type IV collagenase activity increased in serum, obtaining maximum values on Day 8 and Day 15. The measurement of serum proteolytic activity may be of value in the detection of recurrent tumors.
Evaluation of a novel calcium channel blocker, (S)-emopamil, on regional cerebral edema and neurobehavioral function after experimental brain injury
Authors: Okiyama Koichi , Smith Douglas H. , Thomas Mark J. , McIntosh Tracy K.
Published: May 2009

✓ The authors investigated the effects of a novel calcium channel blocker, (S)-emopamil, on cerebral edema and neurobehavioral and memory function following experimental fluid-percussion brain injury in the rat. Two independent experiments were performed to evaluate the effects of this compound on cardiovascular variables and postinjury cerebral edema (increases in tissue water content), and on cognitive deficits and neurological motor function following brain injury. Treatment with (S)-emopamil significantly reduced focal brain edema at 48 hours after brain injury. Profound memory dysfunction induced by brain injury was significantly attenuated following (S)-emopamil treatment. In addition, (S)-emopamil also attenuated the deficits in motor function that were observed over a 2-week period following brain injury. These results suggest that changes in calcium homeostasis may play an important role in the pathogenesis of trauma to the central nervous system and that the calcium channel blocker (S)-emopamil might be a useful compound for the treatment of traumatic brain injury.
Multiloculated hydrocephalus: craniotomy and fenestration of intraventricular septations
Authors: Nida Todd Y. , Haines Stephen J.
Published: May 2009

✓ Ten pediatric patients with multiloculated hydrocephalus caused by neonatal meningitis, ventriculitis, or intraventricular hemorrhage were surgically treated over a 14-year period (January 1, 1976, to December 31, 1990). Six patients underwent craniotomy and transcallosal fenestration of intraventricular septations followed by placement of a shunt, while the other four were treated by shunting procedures alone. Craniotomy resulted in reduction of the shunt revision rate from a median of 2.75 per year prior to fenestration to 0.25 per year following fenestration, with median observation periods of 44.5 and 27 months, respectively. This was compared to a median revision rate of 0.55 per year for patients treated with shunting procedures alone. There were no deaths in either group. Although no surgical complications were encountered, one patient did require a second fenestration procedure. The important aspects of multiloculated hydrocephalus, including pathophysiology, radiographic correlates, and treatment options, are discussed. The goal of treatment is to eliminate the need for multiple shunt revisions, minimizing the accompanying morbidity and expense. It is concluded that craniotomy and transcallosal fenestration of intraventricular septations is a successful treatment of multiloculated hydrocephalus.
Metabolism in the globus pallidus after fetal implants in rats with nigral lesions
Authors: Eisenberg Howard M. , Kadekaro Massako , Freeman Sondra , Terrell Mary Lee
Published: May 2009

✓ The effect of fetal mesencephalic implants on glucose utilization in selected brain structures and on apomorphine-induced rotational behavior was measured in rats with a unilateral lesion of the substantia nigra. Ipsilateral, but not contralateral, implants decreased the rotational behavior induced by apomorphine. In addition, the nigral lesion decreased glucose utilization in the dorso- and ventrolateral quadrants of the striatum and in the entopeduncular nucleus but increased glucose utilization in the ipsilateral globus pallidus and lateral habenula. The increased metabolism in the globus pallidus was attenuated by ipsilateral, but not contralateral, mesencephalic implants which also decreased glucose utilization in the dorsomedial caudate nucleus. These results indicate that the ability of an ipsilateral mesencephalic graft to ameliorate the motor behavior in rats with nigral lesions is associated with changes in the functional activity of the ipsilateral globus pallidus.
Effect of systemic hypotension on cerebral energy metabolism during chronic cerebral vasospasm in primates
Authors: Handa Yuji , Kubota Tetsuya , Tsuchida Akira , Kaneko Masanori , Caner Hakan , Kobayashi Hidenori , Kubota Toshihiko
Published: May 2009

✓ The influence of systemic hypotension on cerebral blood flow (CBF) and energy metabolism during chronic cerebral vasospasm after subarachnoid hemorrhage was studied in 15 monkeys. Changes in the phosphorus spectrum, as demonstrated by in vivo phosphorus-31 (31P) magnetic resonance (MR) spectroscopy, or in regional CBF were measured in the parietal cortex during graded hypotension. Sequential changes in the phosphorus spectrum were observed during moderate hypotension in the animals 7 days after the introduction of an autologous blood clot around the right middle cerebral artery (MCA). Angiograms revealed a reduction in vessel caliber by approximately 50% in the right MCA. The mean CBF in the spasm side decreased in parallel with a decrease in the mean arterial blood pressure (MABP) from 120 to 40 mm Hg, indicating the abolition of autoregulation. There were no significant differences in the mean percentage totals of inorganic phosphate (Pi), phosphocreatine (PCr), adenosine triphosphate (ATP), and pH between the hemispheres at baseline MABP before hypotension. The values of PCr, ATP, and pH decreased significantly (p < 0.05) and Pi increased significantly (p < 0.05) at an MABP of less than 60 mm Hg in the involved hemisphere. The ratio of PCr:Pi decreased in parallel with a decrease in MABP. The ATP showed a stepwise decrease during moderate hypotension (MABP 60 mm Hg) and was reduced significantly 20 minutes after the beginning of hypotension (p < 0.05). The results indicate that, during chronic vasospasm, changes in cerebral energy metabolism are coupled with changes in CBF in the state of impaired autoregulation. There exists a critical level for ischemia below which high-energy phosphorus metabolites become markedly depleted. It is suggested that 31P MR spectroscopy may be useful to evaluate the ischemic vulnerability of brain tissue in order to prevent delayed neurological deficit during cerebral vasospasm.
Intraspinal extradural meningeal cyst demonstrating ball-valve mechanism of formation
Authors: Rohrer Daniel C. , Burchiel Kim J. , Gruber David P.
Published: May 2009

✓ A diverse collection of unverified theories as to the etiology of extradural meningeal cysts have been previously proposed. One case of intraspinal extradural meningeal cyst of the thoracolumbar region is presented in which a ball-valve mechanism involving an idiopathic dural rent and a herniated segment of an underlying dorsal rootlet was suggested by the operative findings. Closure of the dural rent with marsupialization of the meningeal cyst obliterated this extradural lesion. The ball-valve mechanism of formation and other previously proposed theories are discussed.
Parvalbumin and calbindin D-28K immunoreactivity in central ganglioglioma and dysplastic gangliocytoma of the cerebellum
Authors: Ferrer Isidro , Isamat Fabián , López-Obarrio Luis , Conesa Gerardo , Rimbau Jordi , Alcántara Soledad , Español Isabel , Zújar María José
Published: May 2009

✓ Calbindin D-28K and parvalbumin immunocytochemistry were used in the study of central ganglionic cell tumors. Most neurons in the ganglioglioma were immunoreactive to calbindin D-28K, but a few cells were labeled with antibodies against parvalbumin. In contrast, most cells in dysplastic gangliocytoma of the cerebellum were parvalbumin immunoreactive, but fewer reacted with anti-calbindin antibodies. These latter cells had two or three dendrites with claw-shaped terminals and axons with recurrent collateral branches and varicose terminals filled with strings and buttons. These observations suggest that central ganglionic cell tumors, including dysplastic gangliocytoma of the cerebellum, are composed of neurons which, on the basis of their calcium-binding protein content, have particular metabolic and electrophysiological properties.
Total calvarial reconstruction for sagittal synostosis in older infants and children
Authors: Hudgins Roger J. , Burstein Fernando D. , Boydston William R.
Published: May 2009

✓ Premature closure of the sagittal suture is the most common form of craniosynostosis, but this condition occasionally goes unrecognized until the child is too old to undergo procedures that depend upon continued calvarial growth for success. As the entire calvaria is affected and thus misshapen by sagittal synostosis, late correction involves total calvarial reconstruction. The extensive nature of this undertaking has precluded its utilization despite the presence of significant deformities. Adapting the techniques and experience gained from craniofacial surgery, the authors performed total calvarial reconstruction on nine children with sagittal synostosis and subsequent scaphocephaly diagnosed after the age of 1 year. In each case the goals of shortening the anteroposterior length, widening the biparietal diameter, and reducing frontal and occipital deformities were met. Morbidity consisted of acute blood loss, postoperative hyponatremia, and in one case a residual skull defect. The rationale for this procedure and the techniques utilized are discussed.
Transsphenoidal adenomectomy for growth hormone-secreting pituitary adenomas in acromegaly: outcome analysis and determinants of failure
Authors: Tindall George T. , Oyesiku Nelson M. , Watts Nelson B. , Clark Richard V. , Christy James H. , Adams David A.
Published: May 2009

✓ The results of transsphenoidal adenomectomy for growth hormone (GH)-secreting pituitary adenomas in acromegaly performed over a 17-year period were analyzed retrospectively to determine which preoperative factors significantly influenced the long-term surgical outcome. These variables were then used to develop a logistic regression model to determine the probability of surgical failure.

The series consisted of 103 patients. Long-term follow-up study (mean duration 102 ± 64 months) was performed to derive outcome analysis and determinants of failure. Surgical control was defined as a long-term postoperative serum basal GH level of less than 5 µg/liter, a long-term postoperative serum somatomedin C (SM-C) level of less than 2.2 U/ml, and a favorable clinical response. Eighteen (17.5%) patients did not meet these criteria. The overall control rate by the GH criteria was 81.3% and by the SM-C criteria 76.2%.

By multivariate logistic regression analysis, tumor stage was the strongest predictor of outcome (p < 0.05). The preoperative GH level, tumor grade, and preoperative SM-C level were significant univariate predictors (p < 0.05). There were statistically significant differences in mean preoperative GH and SM-C levels (p < 0.05, t-test) and tumor stage (p < 0.05, chi-squared test) between patients whose acromegaly was controlled by surgery and those whose acromegaly was not. Furthermore, estimates were derived of the probability of surgical failure based on preoperative GH level, preoperative SM-C level, and tumor grade and stage. The authors believe these findings will enhance clinical decision-making for neurosurgeons considering transsphenoidal microsurgery in patients with acromegaly.
Mapping of sensory responses to epidural stimulation of the intraspinal neural structures in man
Authors: Barolat Giancarlo , Massaro Fulvio , He Jiping , Zeme Sergio , Ketcik Beth
Published: May 2009

✓ A database is presented of sensory responses to electrical stimulation of the dorsal neural structures at various spine levels in 106 subjects subjected to epidural spinal cord stimulation. All patients were implanted for chronic pain management and were able to perceive stimulation in the area of pain. All patients entered in this study were able to reliably report their stimulation pattern. Several patients were implanted with more than one electrode array. The electrode arrays were placed in the dorsal epidural space at levels between C-1 and L-1. The structures that were likely involved include the dorsal roots, dorsal root entry zone, dorsal horn, and dorsal columns. At the present time, exact characterization of the structure being stimulated is possible only in limited instances. Various body areas are presented with the correspondent spine levels where implanted electrodes generate paresthesias. Areas that are relatively easy targets for stimulation are the median aspect of the hand, the abdominal wall, the anterior aspect of the thigh, and the foot. Some areas are particularly difficult to cover with stimulation-induced paresthesias; these include the C-2 distribution, the neck, the low back, and the perineum.