Middle Branch Research Articles

Factors affecting haemorrhagic transformation in middle cerebral artery infarctions

Objective: Haemorrhagic transformation (HT) affects treatment and prognosis in patients with acute ischaemic stroke. The factors affecting haemorrhagic transformation in infarcts due to occlusion of middle cerebral artery (MCA) stem or branch were investigated. Materials and methods: Of 412 patients who were followed in our clinic between January 2001 and December 2001 with acute ischaemic stroke, 86 patients with occlusion in MCA stem or branch were enrolled in this study. These patients were divided into 2 groups, those with HT ( n=35) and without HT ( n=51). Age, sex, systemic arterial hypertension, diabetes mellitus, blood glucose level in the acute period, renal and liver function tests, systolic and diastolic arterial blood pressure in the acute period, previous cerebrovascular disease, leukoaraiosis, modified Rankin Disability Score (mRDS) and stroke subtype were evaluated. Results: High blood glucose level in the acute period and presence of leukoaraiosis on cranial computerized (CCT) tomography were detected as risk factors in development of HT. HT was seen more frequently in MCA stem infarction than branch infarction. mRDS were worse in the group with HT. In multivariate analysis, there were independent relationships between mean blood glucose level on admission, mRDS, presence of diabetes mellitus, and MCA stem infarction and development of haemorrhagic transformation in patients with MCA territorial infarction.

Anatomical study for transposition of the greater trochanter bone flap pedicled with middle gluteal muscle branch of lateral femoral circumflex vessel

目的 为带旋股外侧血管升支臀中肌支大转子骨瓣转移治疗股骨头缺血性坏死提供解剖学依据.方法在32侧经动脉灌注红色乳胶的下肢标本上,对旋股外侧血管升支臀中肌支的走行及分布进行观察,设计带旋股外侧血管升支臀中肌支大转子骨瓣转移治疗股骨头缺血性坏死的手术方法.结果臀中肌支是旋股外侧血管升支在阔筋膜张肌肌门处向后上的分支,一部分分支向臀中肌止点方向走行,成网状分布于大转子尖端的上面和外侧面.臀中肌支起点外径为(1.0±0.3)mm,一般有2支,起点至大转子止点长度为(4.0±1.3)cm,距离升支起点距离为(4.9±0.8)cm,手术切取的骨瓣范围可达1.5cm×2 5em×1.5 cm.结论旋股外侧血管升支臀中肌支大转子骨瓣转移,可以为股骨头提供丰富的血运,是一种治疗股骨头缺血性坏死简便、微创及有效的方法。

Pesticides in surface water runoff in south-eastern New York State, USA: seasonal and stormflow effects on concentrations.

Samples from two streams (Kisco River and the Middle Branch of the Croton River) in the Croton Reservoir system in south-eastern New York State, USA were sampled from May 2000 through to February 2001 in order to document the effect of land use, streamflow and seasonal patterns of application on pesticide concentrations in runoff from developed watersheds. Many of the pesticides detected most commonly in this study are generally used in developed areas, and particularly on turfgrass. Pesticide concentrations were generally higher, and the numbers of compounds were generally larger, in samples from the Kisco River than in samples from the Middle Branch, probably because the Kisco River drainage has a greater population density and is more extensively developed. Four pesticides (2,4-D, 2,4-D-methyl, dicamba and metalaxyl) were detected in at least one sample from the Kisco River at a concentration >1 microg litre(-1), and no pesticides were detected at concentrations >0.4 microg litre(-1) in Middle Branch samples. No human-health-based water-quality standards were exceeded by samples from either site in this study, but samples from the Kisco River contained four insecticides (carbaryl, chlorpyrifos, diazinon and malathion) and one herbicide (2,4-D) in concentrations that exceeded water quality criteria for the protection of aquatic life. The highest concentrations of most compounds occurred during stormflows in both streams in June, September and December, 2000. The lowest concentrations of most compounds at both sites occurred during baseflows from October 2000 through February 2001, even though the concentrations of many compounds increased substantially at the Kisco River site during stormflows in November and December. Detailed data on the variability of pesticide concentrations during stormflows indicate that there may be two sources of pesticides in the Kisco River watershed: (1) elevated concentrations of pesticides during peak flows that occur early in stormflows likely reflect runoff from paved areas, and (2) elevated concentrations during peak flows that occur later in stormflows from areas with lesser amounts of pavement. Data from the Kisco River indicate that the relation between storm discharge and pesticide concentrations varies among compounds, in part because of variation in seasonal application patterns. These variations in the timing of application result in not all stormflows producing increased concentrations of pesticides. Overall, these results indicate the importance of stormflow sampling throughout the year in assessing pesticide fate and transport in urbanized, developed areas.

Neurogenic vasodilation of dural blood vessels is not mediated by cholinergic transmission in the anaesthetised rat

Dural vessel dilation induced by activation of trigeminal sensory fibres may be responsible for some component of the migraine attack. The presence in some patients with migraine and cluster headache of clinical features, such as lacrimation, suggests cranial parasympathetic activation and poses the question as to whether neurogenic meningeal dilatation has a cholinergic component. Rats were prepared in order to record on-line the diameter of a middle meningeal artery branch through a closed cranial window using an intravital microscope coupled to a video dimension analyser. Acetylcholine (1 μg, intravenously, i.v.) was administered before and after muscarinic receptor inhibition ( n=5) with scopolamine (2 mg/kg, i.v.) or nicotinic receptor inhibition ( n=6) with mecamylamine (4 mg/kg, i.v.). Further vasodilation was induced by electrical stimulation of the cranial window surface before and after muscarinic receptor inhibition with i.v. scopolamine ( n=8). The mean dural vessel percentage increase caused by acetylcholine stimulation was significantly different before and after muscarinic receptor inhibition ( P=0.045). Moreover, there was no difference between the post receptor inhibition values and those obtained after vehicle infusion ( P=0.431). In contrast, no difference was detected in the effect of acetylcholine before and after nicotinic receptor inhibition ( P=0.688). In the second experiment, where the effect of muscarinic receptor inhibition on the neurogenic dilation model was assessed, no significant difference was demonstrated ( P=0.538). Cholinergic dilation of the rat dural arteries is mediated by muscarinic receptors, but this mechanism does not play a significant role in the rat dural vessel dilation induced by closed cranial window electrical stimulation.

Differential activation of potassium channels in cerebral and hindquarter arteries of rats during simulated microgravity.

The purpose of this study was to test the hypothesis that differential autoregulation of cerebral and hindquarter arteries during simulated microgravity is mediated or modulated by differential activation of K(+) channels in vascular smooth muscle cells (VSMCs) of arteries in different anatomic regions. Sprague-Dawley rats were subjected to 1- and 4-wk tail suspension to simulate the cardiovascular deconditioning effect due to short- and medium-term microgravity. K(+) channel function of VSMCs was studied by pharmacological methods and patch-clamp techniques. Large-conductance Ca(2+)-activated K(+) (BK(Ca)) and voltage-gated K(+) (K(v)) currents were determined by subtracting the current recorded after applications of 1 mM tetraethylammonium (TEA) and 1 mM TEA + 3 mM 4-aminopyridine (4-AP), respectively, from that of before. For cerebral vessels, the normalized contractility of basilar arterial rings to TEA, a BK(Ca) blocker, and 4-AP, a K(v) blocker, was significantly decreased after 1- and 4-wk simulated microgravity, respectively. VSMCs isolated from the middle cerebral artery branches of suspended rats had a more depolarized membrane potential (E(m)) and a smaller K(+) current density compared with those of control rats. Furthermore, the reduced total current density was due to smaller BK(Ca) and smaller K(v) current density in cerebral VSMCs after 1- and 4-wk tail suspension, respectively. For hindquarter vessels, VSMCs isolated from second- to sixth-order small mesenteric arteries of both 1- and 4-wk suspended rats had a more negative E(m) and larger K(+) current densities for total, BK(Ca), and K(v) currents. These results indicate that differential activation of K(+) channels occur in cerebral and hindquarter VSMCs during short- and medium-term simulated microgravity. It is further suggested that different profiles of channel remodeling might occur in VSMCs as one of the important underlying cellular mechanisms to mediate and modulate differential vascular adaptation during microgravity.

Metal accumulation in Baltimore Harbor: current and past inputs

The analysis of sediment cores taken from 3 regions of Baltimore Harbor, Maryland, USA, provide insight into contamination in the 20th century, as well as in earlier times. Overall, while there appears to have been a decrease in concentration for most metals over the last 20 a, concentrations of some metals in surface sediment layers, such as Cr and Pb, are still elevated. The deeper sediments, which reflect times before 1900, often contained higher concentrations of metals and reflect a large historical contamination of this region due to industrial inputs and other activities. Mining and smelting impacts are apparent, being reflected by elevated concentrations of Zn, Pb, Cu, Cd and As, and such impacts are seen in the Middle Branch of the estuary during the 1700s and elsewhere in the 1800s as Cu and other ore processing, and steel manufacture, increased. Comparison of the profiles for the metals, and accumulation rates, suggest that the sources of most metals are different. For each site, the particular metal signature recorded in the sediment can be explained in terms of the known activities in the watershed. At one site, sediments from the period prior to the European settlement were analyzed and these show low concentrations reflective of the situation before industrialization and urbanization of the watershed.

Investigation of Effects of Cerebrovascular Morphogy on Hemodynamics Using Image-Based Simulations

In the present study, an image-based simulation system has been developed in order to investigate the relationship between vascular morphology and cerebral hemodynamics. The simulation system consists of medical image-based geometric modeling, grid generation, finite element fluid simulation, and scientific visualization. The paper has developed an effective smoothing method for over-tessellated polygonal surfaces by combining polygon reduction and smoothing techniques. The simulations are conducted for 19 cases of the bifurcation segment of middle cerebral artery branches. The multiple regression analysis is performed based based on 19 cases to examine the effects of cerebrovascular morphology on wall shear stresses. As a result, diameter of MCA, ratio of diameter of branching artery to that of MCA, and bifurcation angle between MCA and the branching artery are important morphological factors in determining the maximum wall shear stresses.

Quelle méthode d’angiographie pour prédire le risque coronaire en 2003 ?: Aspects réglementaires et pratiques de l’utilisation de la coronarographie, de l’IRM et de l’angioscanner

In 2003, risk stratification in coronary heart disease is routinely performed by the results of coronary angiogram, the invasive gold standard angiography. Combined with the left ventricular ejection fraction assessment, the classification in one, two or three vessel disease remain the cornerstone of the revascularization strategy despite well-knowm limitations of this approach. Invasive coronary angiography is a mature technic with recommendations for training program and guidelines for indications. By comparison, the new noninvasive coronary imaging tools, computed tomography (CT) and magnetic resonance (MR) imaging, are just emerging. Coronary artery MR angiography is one of the most challenging areas because of the size and topology of the coronary arteries, as well as cardiac and respiratory motion. Multidetector-row and multisclice spiral computed tomography appear of most value for the detection of coronary artery disease with an excellent negative predictive value for proximal and middle main branches. Together, MR and CT, provide unique information that may predict cardiovascular risk. They identify flow-limiting coronary stenoses and calcified plaques, directly image the atherosclerotic lesions, measure atherosclerotic burden and characterize plaque components. Nevertheless, invasive coronary angiography still remain the first step of percutaneous coronary intervention. Therefore, one of the ultimate goals for the clinicians is the identification of the high-risk patient through a combination of strategies such as assessment of conventional risk factors, blood markers, and imaging. Indifferently to the imaging tool, the treatment should consider a human being and not only a picture.

Quelle méthode d'angiographie pour prédire le risque coronaire en 2003 ? Aspects réglementaires et pratiques de l'utilisation de la coronarographie, de l'IRM et de l'angioscanner

In 2003, risk stratification in coronary heart disease is routinely performed by the results of coronary angiogram, the invasive gold standard angiography. Combined with the left ventricular ejection fraction assessment, the classification in one, two or three vessel disease remain the cornerstone of the revascularization strategy despite well-known limitations of this approach. Invasive coronary angiography is a mature technic with recommendations for training program and guidelines for indications. By comparison, the new noninvasive coronary imaging tools, computed tomography (CT) and magnetic resonance (MR) imaging, are just emerging. Coronary artery MR angiography is one of the most challenging areas because of the size and topology of the coronary arteries, as well as cardiac and respiratory motion. Multidetector-row and multisclice spiral computed tomography appear of most value for the detection of coronary artery disease with an excellent negative predictive value for proximal and middle main branches. Together, MR and CT, provide unique information that may predict cardiovascular risk. They identify flow-limiting coronary stenoses and calcified plaques, directly image the atherosclerotic lesions, measure atherosclerotic burden and characterize plaque components. Nevertheless, invasive coronary angiography still remain the first step of percutaneous coronary intervention. Therefore, one of the ultimate goals for the clinicians is the identification of the high-risk patient through a combination of strategies such as assessment of conventional risk factors, blood markers, and imaging. Indifferently to the imaging tool, the treatment should consider a human being and not only a picture.

Arterial anatomy of the auricle: its importance for reconstructive surgery

Because the auricle is an organ that is both used as a flap in reconstructive surgery and is often exposed to trauma, the arterial distribution of the auricle is of great importance. The aims of this study were to investigate the auricular branches of the posterior auricular artery (PAA) and superficial temporal artery (STA), to determine the vascular territory of various auricular flaps for flap design. Fifteen human male cadaver auricles were used for this study. A branch of the STA to the ear lobe (lower branch) was present in only five auricles (33%). Branches distributing the tragus were small and short arterioles (middle branch of the STA) which were present in 14 auricles (93%). The upper branch of the STA ascends the ascending helix, giving off sub-branches. Some of these sub-branches traverse to the posterior surfaces of the ear and communicate with branches of the PAA. The upper branch was present in all auricles. In 10 auricles (67%), the PAA terminated on the posterior auricular surface, whereas in five auricles (33%) it continued and distributed to the parietotemporal area. The arterial network which was obvious in the middle region of the posterior auricular surface was formed from the middle branch and some sub-branches of the upper branch of the PAA, which was found in 10 auricles (67%). We are convinced that the PAA is the dominant artery for the auricle and the arterial network of posterior auricular surface is better developed in the middle region than the other regions.

Defective sonic hedgehog signaling in esophageal atresia with tracheoesophageal fistula

Background. The pathogenesis of esophageal atresia and tracheoesophageal fistula (EA/TEF) remains unknown. We have found previously that an initial esophageal atresia, followed by an abnormal (absent) branching pattern of the middle branch of a trifurcation of the lung/tracheal bud, leads to the neonatal finding of TEF. Mice null mutant for hedgehog signaling can experience the development of EA/TEF, but the mechanism for this development is also unknown. Given that EA/TEF in humans appears not to be due to genetic defects, a hedgehog mutation cause seems very unlikely. However, defective hedgehog signaling that is caused by environmental effects in the human embryo likely could be implicated. We studied a teratogen-induced model of EA/TEF to determine the mechanism by which defective hedgehog signaling may lead to EA/TEF. Methods. We injected Adriamycin into pregnant rats to induce EA/TEF in rat embryos. We first quantified sonic hedgehog (Shh) signaling pathway molecule expression using real-time, semiquantitative reverse-transcriptase polymerase chain reaction for Shh, Shh receptors (patched and smoothened), and downstream intracellular targets of those receptors (Gli family members). On the basis of these findings, we then developed an in vitro culture system for the day-12 embryonic TEF and manipulated Shh signaling using either exogenous Shh or Shh inhibitors. Results. By reverse transcriptase-polymerase chain reaction, a unique difference between the fistula tract and control tissues was that Gli-2 (downstream signaling molecule of Shh) messenger RNA levels were much lower in the fistula tract than in the adjacent esophagus (P =.002). Surprisingly, in the culture experiments, the fistula tract was induced to branch by exogenous Shh. Such branching of the fistula was unexpected and further supports the presumed respiratory origin of the fistula tract because the normal lung, but not normal esophagus, branched in response to Shh. The Shh inhibitor had no effect, which indicated that defective signaling, rather than hyperfunctioning Shh, is critical to the nonbranching phenotype of the fistula tract in TEF. Conclusion. The recapitulation of respiratory developmental morphogenesis by the fistula tract of TEF in the presence of exogenous Shh, together with the quantitative reduction in normal, endogenous levels of Gli-2, strongly suggests that 1 mechanism for the formation of the fistula tract is the lack of proper Shh signaling because of Gli-2 deficiency, with subsequent straight, nonbranching caudal growth of the fistula tract. This deficiency can be rescued by excess exogenous Shh, thus reestablishing respiratory morphogenesis. (Surgery 2003;134:345-50.)

Right anterior sector drainage in right-lobe live-donor liver transplantation.

The necessity of providing venous drainage for the right anterior sector of a right-lobe graft in adult-to-adult right-lobe live-donor liver transplantation has been controversial. Inclusion of the middle hepatic vein in the right-lobe graft to ensure better early graft function is also under debate. This report summarizes the views of five Asian centers on the necessity of providing venous drainage to the right anterior sector in a right-lobe graft as presented at the Asian Living Donor Transplantation Symposium 2002. All five centers recognize the importance of adequate drainage of the right anterior sector, but they adopt different approaches in including the middle hepatic vein in the graft. Tokyo University uses an occlusion test of the right hepatic artery and middle hepatic vein to define whether the right anterior sector is dusky or regurgitation of blood flow is present in the right anterior portal vein before the decision is made for middle hepatic vein reconstruction. The Asan Medical Center uses hydrostatically dilated saphenous venous graft to anastomose prominent segment V and VIII hepatic vein branches to the inferior vena cava. The University of Hong Kong Medical Centre includes the middle hepatic vein in every graft and anastomoses it to the recipient's middle or left hepatic vein. Kyoto University uses venous jump graft for anastomosing prominent middle hepatic vein branches to the inferior vena cava for recipients receiving a small-for-size graft or graft with dominant middle hepatic vein drainage. The Chang Gung Memorial Hospital adopts a flexible approach in inclusion of the middle hepatic vein in the graft depending on the donor size and the hepatic venous configuration of the right-lobe graft. In summary, the criteria for inclusion and reconstruction of the middle hepatic vein vary. Further analysis is needed to confirm the importance of adequate drainage of the right anterior sector in right-lobe live-donor liver transplantation.

Assessment of vasoreactivity using videodensitometry coronary angiography.

Previous studies demonstrated that the dysfunction of vasomotor tone (VT) is closely linked to the development of atherosclerosis and it is considered important in the very early stages of atherogenesis. Currently, the evaluation of VT relies on lumen changes in response to vasoactive stimuli using quantitative coronary angiography (QCA) based on geometric edge detection (ED). However, using ED for measuring lumen diameters is inherently associated with large uncertainties. Videodensitometry (VD) methods have important advantages over ED for QCA. The objective of this study was to investigate the reliability of VD and ED techniques in determining the effect of nitroglycerin (NTG) on cross-sectional area (CSA) and volume changes in a swine animal model for evaluating coronary vasoreactivity. Coronary angiography was performed on four anesthetized swine. CSA and volume were measured in the left anterior descending (LAD) coronary artery using VD before and after intracoronary injection of 0.3 mg of NTG. CSA was also calculated using standard QCA based on ED. The average CSA changes in the proximal, middle and distal branches measured using VD were 23.83% (+/-10.76%), 30.78% (+/-18.39%), and 27.34% (+/-36.53%), respectively. Similarly, the average CSA changes in the proximal, middle, and distal branches measured using ED were 15.02% (+/-36.38%), 22.02% (+/-26.12), and 38.00% (+/-48.31%), respectively. The average lumen volume change measured using VD was 29.79% (+/-14.79%). In order to evaluate the relative reliability of the techniques. the significance of deviation (SOD) was calculated, which is the ratio of the change after NTG and the measurement error. The average SOD for CSA for all the branches based on VD and ED were 1.86 and 0.69, respectively. The SOD for volume measurement was 2.78. Lumen changes measured by VD showed substantial improvement in reliability when compared to the ED. Moreover, VD can be used to measure substantially smaller changes in lumen dimension in response to vasoactive stimuli than the standard QCA based on ED. Finally, VD allows the measurement of arterial volume, which is not possible with ED.

An Accretion Model for the Growth of the Central Black Hole Associated with Ionization Instability in Quasars

A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole (BH) harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the S-shaped ionization instability of the quasar accretion disk. For a given external mass transfer rate supplied by the quasar host galaxy, ionization instability can modify the accretion rate in the disk and separate the accretion flows of the disk into three different phases, like an S-shape. We suggest that the bright quasars observed today are those quasars with disks in the upper branch of the S-shaped instability, and the faint or 'dormant' quasars are simply these systems in the lower branch. The middle branch is the transition state, which is unstable. We assume the quasar disk evolves according to the advection-dominated inflow-outflow solution (ADIOS) configuration in the stable lower branch of the S-shaped instability, and the Eddington accretion rate is used to constrain the accretion rate in the highly active phase. The mass ratio between a BH and its host galactic bulge is a natural consequence of an ADIOS. Our model also demonstrates that a seed BH approx. 2 x 10(exp 6) solar masses similar to those found in spiral galaxies today is needed to produce a BH with a final mass of approx. 2 x 10(exp 8) solar masses.

Surgical anatomy of the sphenopalatine artery in lateral nasal wall.

We investigated the surgical anatomy of the sphenopalatine artery. First, the location of the sphenopalatine foramen on the lateral nasal wall and the pattern of the main branches of the sphenopalatine artery from the sphenopalatine artery were studied. Second, the course of the posterior lateral nasal artery with respect to the posterior wall of the maxillary sinus, the perpendicular plate of the palatine bone, and the pattern of distribution of its branches on the fontanelle was determined. Third, the distribution pattern on the inferior turbinate was analyzed. Fifty midsagittal sections of randomly selected Korean adult cadaver heads with intact sphenoid sinus and surrounding structures were used in the study. The mucosa on the sphenopalatine foramen and its surrounding mucosa were removed with a microscissors, a fine forceps, and a pick to expose the sphenopalatine artery under an operating microscope (original magnification x6). The feeding vessels of the superior turbinate were from the septal artery in 36 cases (72%). The feeding vessels to the middle turbinate branch originated from the proximal portion of the posterior lateral nasal artery just after exiting the sphenopalatine foramen in 44 cases (88%). Some portion of the posterior lateral nasal artery ran anterior to the posterior wall of the maxillary sinus in 38%. The major feeding arteries to the fontanelle were from the inferior turbinate branch in 25 cases (50%). In most cases, the inferior turbinate branch was the end artery of the posterior lateral nasal artery (98%). The study provides detailed information concerning the sphenopalatine artery, which we hope will help explain the arterial bleeding that may occur during ethmoidectomy, middle meatal antrostomy, conchotomy, and endoscopic ligation of the sphenopalatine artery.

Identification of the ascending middle cerebral artery branches on digital subtraction angiography.

We aimed to establish a method for identifying the ascending convexity branches of the middle cerebral artery on digital subtraction arteriography. We reviewed 100 randomly chosen lateral internal carotid arteriograms of patients with aneurysms. After identifying the Sylvian triangle, the posterior internal frontal, paracentral, superior internal parietal and pericallosal arteries, we formulated templates in order to assess the position of the angular, posterior parietal, central, precentral and prefrontal arteries. Using the Sylvian triangle as a template, we identified the angular and posterior parietal arteries in 91% and 96% of cases, respectively. Using a combination of the posterior internal frontal, paracentral, superior internal frontal and pericallosal arteries a template could be formulated in 87% of cases. This was successfully used to identify the central arteries. A template derived from the pericallosal artery and Sylvian triangle was used to identify the prefrontal arteries in 83% of cases. Templates can be formulated on the basis of the Sylvian triangle and anterior cerebral artery branches for consistent identification of branches of the ascending complex of the middle cerebral artery on digital subtraction angiography.

Prenatal Prediction of Pulmonary Hypoplasia: Clinical, Biometric, and Doppler Velocity Correlates

Laudy, Jacqueline A. M.; Tibboel, Dick; Robben, Simon G. F.; de Krijger, Ronald R.; de Ridder, Maria A. J.; Wladimiroff, Juriy W.

Effect of neutralization of rat IL-6 bioactivity on collateral blood supply from retrograde flow via cortical anastomoses in the rat central nervous system

The purpose of this study was to determine whether neutralization of rat interleukin-6 (IL-6) bioactivity increases the collateral blood supply from retrograde flow via the major middle cerebral artery branches after experimental middle cerebral artery occlusion in the rat. Seventy rats were randomly allocated to four main groups: Group I (n = 10) consisted of normal controls; Group II (n = 20) underwent craniectomy only; Group III (n = 20) was subjected to middle cerebral artery occlusion; and Group IV (n = 20) underwent middle cerebral artery occlusion and treatment with anti-rat IL-6 antibody. Half of the rats from each of Groups II, III and IV were killed at 24 h and the other half at 72 h after craniectomy alone or occlusion. A single dose of antibody did not affect middle cerebral artery caliber, but administration of three doses resulted in a significant increase in the diameter of middle cerebral artery compared to the findings in the corresponding occlusion-only groups. The results suggest that neutralization of rat IL-6 bioactivity in longterm recovery increases the collateral blood supply from retrograde flow via cortical anastomoses after experimental arterial occlusion in the rat brain. [Neurol Res 2002; 24: 405-408]

Complete discontinuity of the distal fistula tract from the developing gut: direct histologic evidence for the mechanism of tracheoesophageal fistula formation.

The embryogenesis of tracheoesophageal anomalies remains controversial. The purpose of this study was to better define the embryogenesis of developing esophageal atresia with tracheoesophageal fistula (EA/TEF), with specific attention to the controversial issue of whether a discontinuity exists in the foregut during its development of EA/TEF. Pregnant outbred rats were injected with adriamycin (2 mg/kg i.p.) on days 6-9 of gestation (E6-E9). At E12.5 and 13.5, microdissection of the entire foregut was performed. Foreguts were examined by phase microscopy, and serial, precisely transverse sections were created for hematoxylin and eosin (H&E) staining. Gross microdissection of the developing foregut at E12.5 (n = 9) revealed a blind-ending, bulbous fistula tract arising from the middle branch of the tracheal trifurcation (as seen by direct and phase microscopy). No connection with the gut could be appreciated at E12.5, but by E13.5 (n = 10) there was an obvious connection between the fistula and the stomach. Serial H&E transverse sections also demonstrated a blind-ending fistula tract arising from the trachea at E12.5. This fistula tract was clearly discontinuous from the developing stomach, which appeared much further caudal to the end of the fistula tract. These results strongly support a model of experimental TEF wherein the fistula tract arises from a trifurcation of the trachea, and (only during a specific gestational window between days 12.5 and 13.5) there is discontinuity between the fistula tract and the stomach. By day 13.5, the fistula joins with the stomach anlage. These observations in the developing EA/TEF should help to resolve the controversy about the mechanism of EA/TEF formation.

In-Plane Propagation of Cavity Polaritons in aQuantum Semiconductor Microcavity

Considering that the coupling among the heavy-hole exciton, light-holeexciton and the cavity photon can form bipolaritons in a quantumsemiconductor microcavity, we calculate the group velocities of the cavitypolaritons at different incident angles using the coupling model of threeharmonic oscillators. The result indicates that the group velocities of thelow and middle branches of the cavity polaritons have extrema, but the groupvelocities of the high branch increase with the increasing incident angle.