Geodesics of Random Riemannian Metrics

We analyze the disordered Riemannian geometry resulting from random perturbations of the Euclidean metric. We focus on geodesics, the paths traced out by a particle traveling in this quenched random environment. By taking the point of the view of the particle, we show that the law of its observed environment is absolutely continuous with respect to the law of the random metric, and we provide an explicit form for its Radon-Nikodym derivative. We use this result to prove a "local Markov property" along an unbounded geodesic, demonstrating that it eventually encounters any type of geometric phenomenon. We also develop in this paper some general results on conditional Gaussian measures. Our Main Theorem states that a geodesic chosen with random initial conditions (chosen independently of the metric) is almost surely not minimizing. To demonstrate this, we show that a minimizing geodesic is guaranteed to eventually pass over a certain "bump surface," which locally has constant positive curvature. By using Jacobi fields, we show that this is sufficient to destabilize the minimizing property.Comment: 55 pages. Supplementary material at arXiv:1206.494

Accessory thyroid gland at carotid bifurcation presenting as a carotid body tumor: case report and review of the literature

AbstractPatients with carotid body tumors referred to vascular surgeons usually undergo magnetic resonance imaging (MRI) as part of the workup. We present a case report of a 39-year-old woman with a presumed carotid body tumor, as was expected from clinical and MRI findings. At surgery, the ectopic thyroid tissue was suspected, and resection was performed. Histologic examination showed normal thyroid tissue with no sign of malignancy. Postoperative thyroid analysis showed a normally located, properly functioning thyroid gland. Ectopic thyroid glands are generally found in the midline, as a result of abnormal median migration. Their presence lateral to the midline with a proper functioning thyroid gland in its normal position is extremely rare. Although several submandibular thyroid glands have been reported, a close relation with the carotid arteries was described only once. When MRI scans of a presumed carotid body tumor show tumor characteristics that are not fully specific for a carotid body tumor, the possibility of ectopic thyroid tissue should be entertained, which can be the patient's only properly functioning thyroid tissue. In such cases, additional assessment, including thyroid tests, should be considered before surgery

Nerve-preserving aortoiliac reconstruction surgery: Anatomical study and surgical approach

AbstractObjective: Dysfunctional ejaculation and, to a lesser extent, dysfunctional erection caused by disruption of efferent sympathetic pathways is a common complication after aortoiliac reconstruction surgery. The aim was to give an anatomic motivation for a nerve-preserving approach on the basis of right-sided unilateral disruption of lumbar splanchnic nerves. Methods: Anatomic and microscopic analysis of preaortic and para-aortic retroperitoneal regions in human cadavers was performed. Anatomic analysis was conducted of two aortoiliac reconstruction operations performed on human cadavers; one was performed according to a single-blind procedure, the second with a modified procedure. Results: The lumbar splanchnic nerves supplying the superior hypogastric plexus from the right side were found to be less voluminous than the left-sided ones. The superior hypogastric plexus was found slightly shifted to the left of the midsagittal plane across the abdominal aorta and its bifurcation. Microscopic analysis revealed a thin fascia between the aorta and the subperitoneal tissue compartment. This fascia was used as a plain of dissection to mobilize the preaortic nerve-plexuses without damage from the aortic wall. Analysis of the specimens operated on showed a significant difference in nerve disruption. The standard procedure caused total disruption of the superior hypogastric plexus and extensive disruption of the inferior mesenteric plexus. The modified procedure only caused right-sided unilateral disruption of lumbar splanchnic nerves. Conclusion: The autonomic nerves supplying the bladder neck, the vas deferens, and the prostate are closely related to the abdominal aorta and its bifurcation. Right-sided unilateral disruption of lumbar splanchnic nerves without further damage to nervous structures would ensure at least one functional sympathetic pathway remaining after aortoiliac reconstruction surgery. (J Vasc Surg 2001;33:983-9.

Indoleamine-2,3-dioxygenase activity in experimental human endotoxemia

Background: Excessive tryptophan metabolism to kynurenine by the rate-limiting enzyme endothelial indoleamine 2,3-dioxygenase 1 (IDO) controls arterial vessel relaxation and causes hypotension in murine endotoxemia. However, its relevance in human endotoxemia has not been investigated so far. We thus aimed to study changes in blood pressure in parallel with tryptophan and kynurenine levels during experimental endotoxemia in humans. Findings: Six healthy male volunteers were given E. coli lipopolysaccharide (LPS; 4 ng/kg) as a 1-min intravenous infusion. They had levels of soluble E-Selectin and soluble vascular cell adhesion molecule-1 as well as IDO activity assessed as the kynurenine-to-tryptophan plasma ratio by liquid chromatography-tandem mass spectrometry at various time points during a 24 h time course. During endotoxemia, IDO activity significantly increased, reaching peak levels at 8 h after LPS infusion (44.0 ± 15.2 vs. 29.4 ± 6.8 at baseline, P<0.0001). IDO activity correlated inversely with the development of hypotension as shown by random effects linear regression models. Finally, IDO activity exhibited a kinetic profile similar to that of soluble endothelial-specific adhesion molecules. Conclusions: LPS is a triggering factor for the induction of IDO in men. Our findings strongly support the concept that the induction of IDO in the vascular endothelium contributes to hypotension in human sepsis

A hydrogenosome with pyruvate formate-lyase: Anaerobic chytrid fungi use an alternative route for pyruvate catabolism

The chytrid fungi Piromyces sp. E2 and Neocallimastix sp. L2 are obligatory amitochondriate anaerobes that possess hydrogenosomes. Hydrogenosomes are highly specialized organelles engaged in anaerobic carbon metabolism; they generate molecular hydrogen and ATP. Here, we show for the first time that chytrid hydrogenosomes use pyruvate formate-lyase (PFL) and not pyruvate:ferredoxin oxidoreductase (PFO) for pyruvate catabolism, unlike all other hydrogenosomes studied to date. Chytrid PFLs are encoded by a multigene family and are abundantly expressed in Piromyces sp. E2 and Neocallimastix sp. L2. Western blotting after cellular fractionation, proteinase K protection assays and determinations of enzyme activities reveal that PFL is present in the hydrogenosomes of Piromyces sp. E2. The main route of the hydrogenosomal carbon metabolism involves PFL; the formation of equimolar amounts of formate and acetate by isolated hydrogenosomes ex

Sequence analysis of the 5' untranslated region in isolates of at least four genotypes of hepatitis C virus in The Netherlands

The RNAs of hepatitis C virus (HCV) isolates from 62 patients with chronic HCV infection were analyzed by direct sequencing of the 5' untranslated region. Two important sequence motifs were recognized: one between positions -170 and -155 and the other between positions -132 and -117. These motifs are partly complementary. All three previously published genotypes were observed; 34 (55%) isolates were classified as type 1 (including prototype [from the United States] and HCV-BK [from Japan] sequences), 11 (18%) were classified as type 2 (including HC-J6 and HC-J8), and 12 (19%) were classified as type 3 (including EB1); one patient was infected with genotypes 1 and 2. Four (6%) isolates showed aberrant sequences and were therefore provisionally classified as genotype 4. These results indicate the significance of sequence variation among the 5' untranslated regions of different HCV genotypes and indicate that this region could possibly be used for consistent genotyping of HCV isolates

Pseudo-supersymmetry and a Tale of Alternate Realities

We discuss how all variant 10d and 11d maximal supergravities, including star supergravities and supergravities in different signatures, can be obtained as different real slices of three complex actions. As an application we study the recently introduced domain-wall/cosmology correspondence in this approach. We give an example in 9d and 10d where the domain-wall and corresponding cosmology can be viewed as different real slices of the same complex solution. We argue how in this case the pseudo-supersymmetry of the cosmological solutions can be understood as the invariance under supersymmetry of a variant supergravity.Comment: 32 page

Rapid genotyping of hepatitis C virus RNA-isolates obtained from patients residing in Western Europe

Two rapid genotyping methods for hepatitis C virus (HCV), the line probe assay (Inno‐LiPA) and the subtype‐specific core amplification system [Okamoto et al., (1992b) Journal of General Virology 73:673‐679], were applied to 58 HCV isolates which were typed as type 1 (n=37) and type 2 (n=21) by sequence analysis of the 5′ untranslated region (5′UTR). The line probe assay targets the 5′UTR and recognized 12 subtype 1a, 25 subtype 1b, 18 subtype 2a, 2 subtype 2b and 1 subtype 2d in accordance with sequence analysis of this region. Subtype‐specific core amplification revealed 7 discrepancies among the 37 type 1 isolates when compared to LiPA. A different subtype was observed in 3 isolates (la versus 1b), 2 isolates remained untyped and 2 isolates showed a coinfection of subtype la and 1b. The first 5 discrepancies were confirmed by sequence analysis of the core region whereas the coinfection could not be confirmed. Of the 21 type 2 isolates only one could be typed by subtype‐specific core amplification. HCV RNA was detected in all 21 cases after the general first round of polymerase chain reaction (PCR). Direct sequencing of the core region indicated sequence variation as a source of failure. It is concluded that LiPA results are conclusive for typing of HCV. However, LiPA is hampered occasionally for subtyping by lack

Prospective comparative study of spiral computer tomography and magnetic resonance imaging for detection of hepatocellular carcinoma

BACKGROUND: Hepatocellular carcinoma (HCC) is often detected at a relatively late stage when tumour size prohibits curative surgery. Screening to detect HCC at an early stage is performed for patients at risk. AIM: The aim of this study was to compare prospectively the diagnostic accuracy and classification for management of the two state of the art secondline imaging techniques: triphasic spiral computer tomography (CT) and super paramagnetic iron oxide (SPIO) enhanced magnetic resonance imaging (MRI). PATIENTS: Sixty one patients were evaluated between January 1996 and January 1998. Patients underwent CT and MRI within a mean interval of 6.75 days. METHODS: CT and MRI were evaluated blindly for the presence and number of lesions, characterisation of these lesions, and classification for management. For comparison of the data on characterisation, the CT and MRI findings were compared with histopathological studies of the surgical specimens and/or follow up imaging. Data of patients not lost to follow up were available to January 2001. RESULTS: SPIO enhanced MRI detected more lesions and overall smaller lesions than triphasic spiral CT (number of lesions 189 v 124; median diameter 1.0 v 1.8 cm; Spearman rank's correlation coefficient 0.63, p<0.001). There was no significant difference in accuracy between CT and MRI for lesion characterisation. The agreement in classification for management was very good (weighted kappa 0.91, 95% CI 0.83-0.99). CONCLUSION: SPIO enhanced MRI detects more and smaller lesions, but both techniques are comparable in terms of classification for management. SPIO enhanced MRI may be preferred as there is no exposure to ionising radiation