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PubMed1999

Anterior cruciate ligament tears: MR imaging-based diagnosis in a pediatric population.

PURPOSE: To evaluate the diagnostic accuracy of primary and secondary magnetic resonance (MR) imaging findings of anterior cruciate ligament (ACL) tears in young patients with immature skeletal systems. MATERIALS AND METHODS: MR images obtained in 43 patients aged 5-16 years who underwent arthroscopy were retrospectively reviewed. Two reviewers evaluated primary findings (abnormal signal intensity, abnormal course as defined by Blumensaat angle, and discontinuity), secondary findings (bone bruise in lateral compartment, anterior tibial displacement, uncovering of posterior horn of lateral meniscus, posterior cruciate ligament line, and posterior cruciate angle), and meniscal and other ligamentous injuries. RESULTS: There were 19 ACL tears and 24 intact ACLs. Overall sensitivity and specificity of MR imaging in detecting ACL tears were 95% and 88%, respectively. Sensitivities of the primary findings were 94% for abnormal Blumensaat angle; 79%, abnormal signal intensity; and 21% discontinuity. The specificity of all primary findings was 88% or greater. The sensitivity and specificity of the secondary findings, respectively, were 68% and 88% for bone bruise; 63% and 92%, anterior tibial displacement; 42% and 96%, uncovered posterior horn of lateral meniscus; 68% and 92%, positive posterior cruciate line; and 74% and 71%, abnormal posterior cruciate angle. Fifteen (79%) patients had meniscal tears, and five (26%) had collateral ligament injuries. CONCLUSION: Primary and secondary findings of ACL tears in young patients have high specificity and are useful for diagnosis.

Adolescent↗

PubMed1991

Enhanced sensitivity of "metabotropic" glutamate receptors after induction of long-term potentiation in rat hippocampus.

Stimulation of [3H]inositol monophosphate ([3H]InsP) formation by ibotenate or trans-1-aminocyclopentyl-1,3-dicarboxylic acid (t-ACPD) in rat hippocampal slices was enhanced after tetanic stimulation of the Schaffer collaterals projecting to the CA1 region (in vitro) or the perforant pathway projecting to the dentate gyrus (in freely moving animals). This effect was observed 5 h (but not 2 h) after long-term potentiation (LTP) induction and was abolished if tetanic stimulation was performed in the presence of specific antagonists of N-methyl-D-aspartate receptors. The delayed increase in excitatory amino acid-induced polyphosphoinositide (PPI) hydrolysis was accompanied by an enhanced responsiveness to norepinephrine, whereas the basal and carbamylcholine-stimulated [3H]InsP formation were unchanged. These results suggest that an increased activity of "metabotropic" glutamate receptors may contribute to the synaptic mechanisms enabling the late expression and or maintenance of LTP. Accordingly, LTP decayed more rapidly (within 5 h) in rats repeatedly injected with LiCl (60-120 mg/kg, i.p., for 10 days), a treatment that led to a reduced efficacy of ibotenate and norepinephrine in stimulating PPI hydrolysis in hippocampal slices.

Animals↗

PubMed1999

Circle of Willis collateral flow investigated by magnetic resonance angiography.

BACKGROUND AND PURPOSE: The circle of Willis (CW) is considered an important collateral pathway in maintaining adequate cerebral blood flow in patients with internal carotid artery (ICA) obstruction. We aimed to investigate the anatomic variation of the CW in patients with severe symptomatic carotid obstructive disease and to analyze diameter changes of its components in relation to varying grades of ICA obstruction and in relation to the presence or absence of (retrograde) collateral flow. METHODS: Seventy-five patients with minor disabling neurological deficits and with ICA stenoses or occlusions were categorized into 4 groups according to the severity of ICA obstruction. This patient population reflected a relatively favorable subgroup of cerebral infarction (considering their minor neurological deficits). All subjects underwent magnetic resonance angiography, including magnetic resonance angiography sensitive to flow direction. CW morphology and the size of its components were determined and compared with those values in control subjects (n=100). RESULTS: Compared with control subjects, patients demonstrated a significantly higher percentage of entirely complete CW configurations (55% versus 36%, P=0.02), complete anterior configurations (88% versus 68%, P=0.002), and complete posterior CW configurations (63% versus 47%, P=0.04). Patients with severe ICA stenosis did not show significantly increased CW vessel diameters. Patients with ICA occlusion demonstrated a high prevalence of collateral flow through the anterior CW and significantly increased diameters of the communicating channels. Patients with bilateral ICA occlusion relied on collateral flow via the posterior CW and demonstrated a bilateral increase in posterior communicating artery diameters (P<0.05). CONCLUSIONS: The anatomic and functional configuration of the CW reflects the degree of ICA obstruction.

Adult↗

PubMed1977

A fluorometric study of oxidative metabolism in the in vivo canine heart during acute ischemia and hypoxia.

Optical techniques for monitoring the fluorescence of intramitochondrial nicotinamide adenine dinucleotide (NADH) were employed to allow an on-line, non-invasive study of the metabolic state of healthy and ischemic cardiac tissue in the intact dog. Acute interruption of blood flow to the area of myocardium studied resulted in an immediate rise in NADH, indicating impairment of oxidative metabolism due to limitation of oxygen availability. Release of the coronary artery occlusion resulted in an oxidation of NADH to preocclusion baseline and signaled repayment of incurred O2 debt. Collateral flow produced a spontaneous fall in NADH levels towards preocclusion baseline. Hypoxic tissue was recognized by an oxidation of NADH on ventilation with 100 per cent O2, while in normal hearts no oxidation indicated the O2 was not rate limiting. Ischemic NADH increases preceded the onset of epicardial EKG changes, suggesting that an inability to rephosphorylate ADP to ATP is the primary cause of the EKG changes. Fluorometry of the in vivo heart provides a sensitive, continuous technique of monitoring cardiac cellular mitochondrial NAD;NADH redox levels and, therefore, the adequacy of high energy phosphate production and allows localization of cardiac tissue with marginal oxygen supply.

Animals↗

PubMed2006

Internal thoracic artery-inferior epigastric artery as a collateral pathway in aortoiliac occlusive disease.

OBJECTIVE: In patients with aortoiliac occlusion, the internal thoracic artery-inferior epigastric artery (ITA-IEA) collateral is one of the collaterals supplying blood flow to the lower extremity, and the interruption of this collateral may cause severe leg ischemia. The aim of this study was to evaluate by color duplex ultrasonography scans the ITA-IEA pathway and its significance as a collateral in providing lower-extremity perfusion in aortoiliac occlusive disease. METHODS: Color duplex ultrasonography scans were prospectively performed in 64 consecutive patients with aortoiliac occlusion. Blood flow measurement in the ITA, IEA, and common femoral artery was done on both sides. The patients were stratified according to occlusion level (aorta, common iliac artery, external iliac artery), and the data obtained from such groups were compared. RESULTS: In 95% of patients with aortoiliac occlusion, the ITA-IEA pathway was functioning as a collateral, with mean collateral flow of 66 +/- 48 mL/min, and its average contribution to lower-extremity perfusion was 38% +/- 23%. Additionally, a moderately positive correlation was found between flows of ITA and IEA (r = 0.55, P < .0001). Depending on the level of occlusion, the collateral flow and its contribution to perfusion progressively decreased from the proximal to distal aortoiliac occlusion level. Furthermore, the difference in the ITA-IEA flow volume was statistically significant between occlusion levels (P = .009), but the differences in the perfusion contribution were not different among levels (P = .311). There was also no statistical difference between the groups concerning collateral flow volume and contribution to lower-extremity perfusion in relation to unilateral or bilateral occlusion of the iliac artery, the state of distal run-off being good or poor, or the clinical findings being mild or severe. CONCLUSION: In patients with aortoiliac occlusion, the ITA-IEA collateral pathway is an important route providing lower-extremity perfusion. Additionally, Doppler sonographic flow measurements of the contribution of the ITA-IEA route to lower-extremity perfusion may provide beneficial diagnostic information necessary for the pretreatment work-up of patients with aortoiliac occlusion, especially for whom the ITA is planned to be used as a coronary artery graft.

Angiography↗

PubMed2002

Magnetic resonance angiography of collateral compensation in asymptomatic and symptomatic internal carotid artery stenosis.

OBJECTIVE: In patients with stenosis of the internal carotid artery (ICA), the presence of collateral circulatory pathways may be crucial to maintain cerebral perfusion pressure, metabolism, and function. The purpose of the present study was to determine whether patients with asymptomatic stenosis of the ICA have a better collateral ability of the circle of Willis when compared with patients with symptomatic ICA stenosis. METHOD: Magnetic resonance angiography consisting of the circle of Willis was performed in 19 patients with severe asymptomatic ICA stenosis and in 21 patients with severe symptomatic ICA stenosis prior to carotid endarterectomy and in 53 control subjects. Between group comparisons were made for function (directional flow) and anatomy (diameter). RESULTS: In patients with asymptomatic ICA stenosis, the prevalence of collateral flow via the anterior communicating artery was significantly increased (37%, 7 of 19) compared with symptomatic patients (10%, 2 of 21) and control subjects (0%; P <.001). Patients with asymptomatic ICA stenosis demonstrated the largest mean diameter of the anterior communicating artery (1.33 +/- 0.18 mm) compared with patients with symptomatic ICA stenosis (1.22 +/- 0.18 mm) and control subjects (1.06 +/- 0.10 mm, P <.05). No differences in collateral flow pattern or diameter were found for the posterior communicating artery between the groups. CONCLUSIONS: The present cross-sectional study demonstrates the importance of an adequate hemodynamic compensation via the circle of Willis in patients with ICA stenosis. Whether differences in collateral compensation can be used to select patients for CEA has yet to be determined.

Aged↗

PubMedDate not supplied

[Surgical treatment of extensive defects of the tissues and trophic ulcers in the area of the heel tendon using an L-shaped flap].

Operations were conducted on 22 patients with defects in soft tissues and trophic ulcers of cicatrix in the region of the calcaneal tendon. In 16 patients with extensive cicatricial lesions occupying two distal thirds or the whole region, an L-shaped flap of skin and fat was used, it was formed on the postero-lateral distal third of the leg, in the zone of the lateral malleolus and the lateral surface of the foot. The flap measured 20-22 cm in length and 6-7 cm in width. The ratio of the vertical part of the flap to the horizontal part was 3:1, 2:1, or 1:1 depending on the level of the defect and the area of the wound. The flap is mobilized strictly along the fascia so as not to injure the subcutaneous fat. The sural nerve is included in the flap to preserve its sensitivity, the rich venous network of the small saphenous vein provides for drainage, while the perforating arteries of the anterior tibial and fibular arteries, entering the base of the flap, ensure a sufficiently stable collateral circulation. Necrosis of the end of the flap occurred in 2 among 16 patients, in obliteration of the leg arteries (1) and cutting of tissues in the zone of the flap base (1) during previous surgical intervention. Complete healing was achieved in all cases; there were no recurrences in follow-up periods of 6 months to 8 years. The L-shaped flap retained its normal properties, the deformity of the donor site was negligible.

Achilles Tendon↗

PubMed1986

Regional myocardial blood flow and function in experimental myocardial ischemia.

Experiments are reviewed in conscious dogs instrumented with ultrasonic crystals for measuring systolic wall thickening and myocardial blood flow (microsphere technique), and studied under a variety of conditions during acute or chronic circumflex coronary stenosis. With acute progressive stenosis, a nearly linear relation was found between normalized subendocardial flow and function. There were no consistent ST segment changes in the body surface electrocardiogram if wall thickening was less than 25%, although changes occurred in the subendocardial electrogram. The regional flow-function relation was then examined during exercise with various degrees of coronary stenosis; the mean flow-function relation was shifted to the right of the resting relation, but when subendocardial flow was expressed per beat and function normalized as a fraction of that in normal wall the relationship was superimposable upon the resting relation, suggesting that ischemia is absolute (not relative) in the subendocardium during steady state conditions. When the normal increase of wall thickening during exercise was prevented by mild coronary stenosis ischemia could not be clearly detected, but when function during exercise averaged 20% below the resting value, subendocardial blood flow changes and other evidence of ischemia were readily apparent, indicating the sensitivity of wall motion for detecting subcritical coronary stenosis. The regional flow-function relation was also studied in chronic single vessel coronary artery stenosis (ameroid constrictor), in which function was normal at rest (collateral development) but exercise produced large decreases in both regional flow and function. At matched levels of treadmill exercise, a calcium channel blocker (diltiazem) together with beta blockade (atenolol) produced an additive effect that was greater than with either drug alone, with substantial increases in both subendocardial flow and regional function. Finally, studies showing reversible post-reperfusion dysfunction after 15 minutes or two hours of coronary occlusion are reviewed. Partial ischemia for 5-hours, followed by reperfusion also produced regional dysfunction which persisted for at least 3 days but reverted to normal by one week, with little or no histologic damage of the free wall. These studies on regional flow and function during ischemia may carry implications for a number of important clinical phenomena.

Animals↗

PubMed1983

[Clinical significance of stress thallium-201 myocardial scintigraphy for evaluation of right ventricular ischemia].

Although stress thallium (T1)-201 myocardial imaging has been used for evaluation of the ischemic lesion of the left ventricle, there are few reports on the usefulness of this method for the assessment of the right ventricle in ischemic heart disease. The patients (pts) fell into three distinct groups according to the findings of the coronary arteriogram: normal control group (16 cases) without angiographically documented coronary artery disease; non-RCA group (16 cases) with a significant stenosis (greater than or equal to 75% narrowing) in the left coronary artery but free of a significant right coronary artery (RCA) stenosis; RCA group (28 cases) with a significant RCA stenosis regardless of the presence or absence of a significant left coronary artery lesion. After the pts were exercised to 80-85% of the expected maximum heart rate, immediate and delayed (3 to 4 hrs) T1-201 myocardial images were obtained. The images of the right ventricular free wall ( RVFW ) in 30 degrees and 60 degrees left anterior oblique (LAO) projections were evaluated visually with regard to the presence or absence of a defective T1-201 uptake, degree of the radioactivity and redistribution phenomenon of the RVFW . On immediate images, all normal controls and 13 pts in non-RCA group had continuous visualization of the RVFW . In RCA group, the RVFW was not visualized in five and 11 showed defective visualization of the RVFW in the 30 degrees LAO projection. In 60 degrees LAO projection, the RVFW was not visualized in six and five had defective visualization. On delayed images in RCA group, two pts who had no inferior myocardial infarction (MI) had redistribution of T1-201 into the RVFW . Defective visualization of the RVFW on the image was associated with location of the RCA lesion, history of inferior MI and degree of RCA stenosis. Collateral circulation seemed to protect the RVFW against the development of exercise-induced ischemia and affect the occurrence of redistribution of T1-201 into the RVFW . The RVFW findings on images improved the sensitivity for identifying the pts with RCA disease, compared with the LV findings alone. Thus, stress T1-201 myocardial imaging is able to visualize the myocardial blood flow of the RVFW and may provide a useful non-invasive method in the evaluation of right ventricular ischemia.

Adult↗

PubMed2003

Evaluation of cerebral hemodynamics with perfusion MRI in childhood moyamoya disease.

The purpose of our study was to evaluate the role of perfusion MRI and to compare the findings with those of conventional imaging in childhood moyamoya disease (MMD). Perfusion MRI was performed preoperatively on 13 cases of childhood MMD. Based on the perfusion MRI findings, patients were classified into four groups: those with normal regional cerebral blood volume (rCBV) and time to peak (TTP) (group 1, n = 2); those with normal rCBV and delayed TTP (group 2, n = 1); those with increased rCBV and delayed TTP (group 3, n = 5), and those with decreased rCBV and delayed TTP (group 4, n = 5). Lesion volume as determined using the rCBV map was compared with that on MRI and single photon emission computerized tomography (SPECT). The characteristics of groups 1, 2 and 3 were a high frequency of transient ischemic attacks, normal finding on MRI, early angiographic stages, decreased reserve on SPECT and favorable operative outcome. In group 3, angiography revealed abundant collateral channels. In group 4, all cases had infarction on MRI and abnormal perfusion on SPECT. Angiographic stages tended to have progressed, and operative outcome was less favorable. Perfusion MRI documented hemodynamic asymmetries in the five cases with normal MRI. Perfusion MRI is suggested to have a sensitivity intermediate between rest and acetazolamide SPECTs. We conclude that perfusion MRI may be a valuable tool for characterizing and monitoring ischemia in MMD. Perfusion MRI provides additional functional information not available from conventional MRI and has a potential role comparable to SPECT in the evaluation of MMD.

Adolescent↗

PubMed1996

Specificity of diagnostic nerve blocks: a prospective, randomized study of sciatica due to lumbosacral spine disease.

Temporary nerve blocks using local anesthetic are employed extensively in the evaluation of pain problems, particularly lumbosacral spine disease. Their specificity and sensitivity in localizing anatomic sources of pain have never been studied formally, however, and so their diagnostic and prognostic value is questionable. There have been anecdotal reports of relief of pain by temporary blocks directed to areas of pain referral, as opposed to areas of documented underlying pathology; but there has been no study to define the frequency or magnitude of this effect. We have examined the specificity and sensitivity of a battery of local anesthetic blocks in a series of 33 patients with a chief complaint of sciatica, attributable in all cases to spinal disease (radiculopathy, with some clinical features of arthropathy). As determined by blinded patient analog ratings in randomized sequence, three different nerve blocks were significantly more effective than control lumbar subcutaneous injection of an identical volume of 3 ml of 0.5% bupivacaine (P < 0.05). Not only paraspinal lumbosacral root blocks and medial branch posterior primary ramus blocks (at or proximal to the pathology), but also sciatic nerve blocks (distal or collateral to the pathology) produced temporary relief in a majority of patients. This confirmed the study hypothesis that false positive results are common, and specificity is low. For sciatic nerve blocks, specificity was between 24% and 36%. Patterns of responses specific to the established diagnosis of radiculopathy (i.e., root block most effective) had sensitivities between 9% and 42%. Statistical analysis of clinical and technical prognostic factors revealed that the only association with pain relief by any block were the effects of other blocks. The strongest association was between relief by sciatic nerve block and relief by medial branch posterior primary ramus (facet) block (P = 0.001, odds ratio 16.0). There were no associations between the results of blocks and clinical findings (history, physical examination, diagnostic imaging) in these patients, chosen for their homogeneous clinical presentation and absence of functional signs. Our findings indicate a limited role for uncontrolled local anesthetic blocks in the diagnostic evaluation of sciatica and referred pain syndromes in general. Negative blocks or a pattern of responses may have some predictive value, but isolated, positive blocks are non-specific. This lack of specificity may, however, be advantageous in therapeutic applications.

Adult↗

PubMed1993

Imaging of myocardial viability: a head-to-head comparison among nuclear, echocardiographic, and angiographic techniques.

The relationship between radioisotopic, echocardiographic, and angiographic markers of myocardial viability is still to be defined. To this purpose, 14 patients with previous myocardial infarction were studied using a multiparametric approach. Each patient underwent, on separate days, rest thallium 201 and technetium 99m Sestamibi planar scintigraphy, dobutamine/dipyridamole stress echocardiography, and coronary angiography; 11 of these patients underwent also dipyridamole echocardiographic testing. Thallium 201 and Sestamibi uptakes at rest were expressed as percentage of maximal activity in each projection using a 13 segment model. Dobutamine and dipyridamole stress echocardiography were analyzed using a score index ranging from 1 (normokinesis) to 4 (dyskinesis) and a similar segmentation. Coronary angiography was analyzed by quantitative approach. In all patients, follow-up echocardiography was performed following coronary revascularization. Before revascularization, 75 segments showed regional dyssynergies. Thallium 201 showed the highest sensitivity and specificity in the preoperative identification of viability, whereas Sestamibi was affected by a significant number of false-negative studies. Among echocardiographic techniques, dobutamine was slightly superior to dipyridamole in the detection of viable segments. The degree of coronary stenosis failed to predict the recovery of function following by-pass graft or angioplasty in almost all segments; however, in case of occlusion, most viable segments were perfused by adequately collateralized coronary arteries.

Adult↗

PubMed2003

Effectiveness of pulse oximetry screening for congenital heart disease in asymptomatic newborns.

OBJECTIVE: To determine the sensitivity, specificity, predictive value, and accuracy of a program of pulse oximetry screening of asymptomatic newborns for critical congenital cardiovascular malformation (CCVM). METHODS: Pulse oximetry was performed on asymptomatic newborns in the well-infant nurseries of 2 hospitals. Cardiac ultrasound was performed on infants with positive screens (saturation 24 hours). Data regarding true and false positives as well as negatives were collected and analyzed. RESULTS: Oximetry was performed on 11 281 asymptomatic newborns, and 3 cases of CCVM were detected (total anomalous pulmonary venous return x2, truncus arteriosus). During the study interval, there were 9 live births of infants with CCVM from a group of 15 fetuses with CCVM detected by fetal echocardiography. Six infants with CCVM were symptomatic before screening. There was 1 false-positive screen. Two infants with negative screens were readmitted (coarctation, hypoplastic left pulmonary artery with aorto-pulmonary collaterals). Other cardiac diagnoses in the database search were nonurgent, including cases of patent foramen ovale, peripheral pulmonic stenosis, and ventricular septal defect. The prevalence of critical CCVM among all live births was 1 in 564 and among the screened population was 1 in 2256 (sensitivity: 60%; specificity: 99.95%; positive predictive value: 75%; negative predictive value: 99.98%; accuracy: 99.97%). CONCLUSIONS: This screening test is simple, noninvasive, and inexpensive and can be administered in conjunction with state-mandated screening. The false-negative screen patients had lesions not amenable to detection by oximetry. The sensitivity, specificity, and predictive value in this population are satisfactory, indicating that screening should be applied to larger populations, particularly where lower rates of fetal detection result in increased CCVM prevalence in asymptomatic newborns.

Evaluation Studies as Topic↗

PubMed1999

Collateral biliary circulation in portal hypertension syndrome.

OBJECTIVE: to describe collateral circulation in the gallbladder wall in relation with portal hypertension syndrome, and to determine whether this syndrome is frequently associated portal vein thrombosis. METHODS: images were retrospectively reviewed for 9 patients with previously diagnosed portal hypertension syndrome, in whom ultrasound results suggested the presence of varices of the cystic vein. RESULTS: four patients showed signs suggesting portal vein thrombosis. The gallbladder wall showed diffuse hypoechoic thickening in all patients, 7 of whom had intramural dilation of tubular, tortuous appearance. Ultrasound findings, however, were not very specific, and differential diagnosis with a large number of other entities is required to rule out other possible causes of focal and diffuse thickening of the gallbladder wall. The use of Doppler sonographic techniques made it possible to determine the cause of the varices, and to confirm suspicions of portal thrombosis. This method was found to be just as sensitive as ultrasound imaging, and much more specific. Angiograms obtained in 3 patients for different reasons confirmed the ultrasonographic findings in all cases. CONCLUSIONS: this study confirms the association between thromboses and varices, and analyzes the physiopathological hypotheses invoked to explain this association. We emphasize the need for correct diagnosis, given the frequency of surgical iatrogenic bleeding or misdiagnosis resulting from confusion with other possible causes of gallbladder wall thickening. Doppler ultrasound is considered the ideal diagnostic method as it is harmless, sensitive and specific.

Adolescent↗

PubMed2002

Decreased neuronal synchronization during experimental seizures.

Synchronization between CA1 pyramidal neurons was studied using dual-cell patch-clamp techniques simultaneous with an extracellular measurement of network activity. We explored various linear and nonlinear methods to detect weak synchronization in this network, using cross-correlation, mutual information in one and two dimensions, and phase correlation in both broad and narrow band. The linear and nonlinear methods demonstrated different patterns of sensitivity to detect synchrony in this network, depending on the dynamical state of the network. Bursts in 4-amino-pyridine (4AP) were highly synchronous events. Unexpectedly, seizure-like events in 4AP were desynchronous events, both in comparison with interictal periods preceding the seizure without bursts (cut Schaffer collateral tract) and in comparison with bursts preceding the seizures (intact Schaffer collateral tract). The finding that seizure-like events are associated with desynchronization in such networks is consistent with recent theoretical work, suggesting that asynchrony is necessary to maintain a high level of activity in neuronal networks for sustained periods of time and that synchrony may disrupt such activity.

4-Aminopyridine↗

PubMed1994

Potential role of bile duct collaterals in the recovery of the biliary obstruction: experimental study in rats using microcholangiography, histology, serology and magnetic resonance imaging.

Obstructive cholestasis induced in animals at the level of the lobar and common bile ducts is known to be reversible with time. This study was conducted not only to test the hypothesis that formation of bile duct collaterals is responsible for the recovery of biliary obstruction but also to assess the potential of hepatobiliary agent-enhanced magnetic resonance imaging for visualizing cholestasis. A total of 52 rats were divided into three groups with selective biliary obstruction, total biliary obstruction and sham surgery. We studied the evolution of cholestasis by correlating microcholangiographic, histological findings with the results of liver tests and hepatobiliary agent-enhanced magnetic resonance imaging. Lobar cholestasis undetected by liver tests but seen on magnetic resonance imaging as a difference between ligated and unligated lobes, occurred in 15 out of 20 rats subjected to selective biliary obstruction within 48 hr after ligation, and recovered later on as a result of the development of bile duct collaterals. Five rats failed to show local cholestasis as a result of the existence of interlobar accessory bile channels. All 18 total biliary obstruction-treated rats were cholestatic soon after ligation, as confirmed by high serum bilirubin and alkaline phosphatase levels and as documented by poor liver enhancement on magnetic resonance imaging. Cholestasis recovered within 4 wk with normalization of liver enhancement on magnetic resonance imaging as a result of the formation of bile duct collaterals (as demonstrated by microcholangiographic and histological study). Bile duct collateral formation is responsible for the recovery from obstructive cholestasis in rats. A similar mechanism might be present in conditions of bile duct obstruction without cholestasis. Hepatobiliary agent-enhanced magnetic resonance imaging is more sensitive than blood tests in detecting local cholestasis and can be used to monitor noninvasively the evolution of biliary obstruction.

Alanine Transaminase↗

PubMed2003

Functional relation between interneuron input and population activity in the rat hippocampal cornu ammonis 1 area.

Inhibitory interneurons are important components of the cornu ammonis 1 (CA1) network, as they are strategically positioned to control network information transfer. We investigated in detail synaptic input to individual CA1 interneurons (mainly basket and bistratified cells) after the local circuit was activated through the Schaffer-Commissural pathway and related this input to the population activity of the pyramidal cells. Synaptic responses were measured under whole-cell voltage clamp and population activity was determined from local field potentials. The synaptic input that was evoked in CA1 interneurons fell into two distinct groups. Disynaptic input with a long latency always started after the population spike with a mean latency of 3.0+/-0.3 ms (n=22) in respect to the peak of the population spike. This type of synaptic input to the interneurons was causally linked to the occurrence and amplitude of the population spike and most likely driven by CA1 pyramidal cells. Short-latency monosynaptic input occurred 0.8+/-0.2 ms (n=18) before the peak of the population spike. Its timing was strictly linked to the stimulus and showed significantly less jitter than long-latency input. In the absence of a population spike only short-latency input could be observed. Whether an interneuron receives direct monosynaptic Schaffer input or disynaptic input from the pyramidal cell population determines when that interneuron will be recruited in the network after Schaffer collateral stimulation. In addition, we found that the relation between the strength of the synaptic input and the population activity was different for the two types of input. Short-latency monosynaptic input showed large sensitivity to input changes at stimulus intensities that evoked little activity in the pyramidal cell population. In contrast, the amplitude of the long-latency disynaptic input to the interneurons closely reflected the population activity and increased gradually with stimulus intensity. Interneurons receiving the first type of input may expand the input sensitivity of the network, while interneurons receiving the second type could be involved in overall normalization of the output of the CA1 network. Our results underscore the importance of knowledge of the input to an interneuron for the understanding of its inhibitory role in the network.

Animals↗

PubMed2000

[White finger and hypertrophy of the lumbrical muscles].

Within the digital vascularization diseases, we found a compression of the radial and ulnar collateral arteries of a finger by hypertrophy of the lumbrical muscles which was presented clinically in the form of a chronic sub-ischemia. A surgical release made it possible to recover a vascularized and sensitive finger.

Adult↗