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Biomedical subjects

M Sindel

Publications and source records attributed to M Sindel.

15 recordsLinked to original sources
PubMed2005

Frequency-dependent transport through a quantum dot in the Kondo regime.

We study the ac conductance and equilibrium current fluctuations of a Coulomb-blockaded quantum dot in the Kondo regime. To this end we have developed an extension of the numerical renormalization group suitable for the nonperturbative calculation of finite-frequency transport properties. We demonstrate that ac transport gives access to the many-body resonance in the equilibrium spectral density. It provides a new route for measuring this key signature of Kondo physics, which so far has defied direct experimental observation.

Journal Article↗
PubMed2005

Arterial, neural and muscular variations in the upper limb.

During our routine dissection studies we observed arterial, neural and muscular variations in the upper limbs of an adult male cadaver. In this case we observed the superficial brachial artery origination from the third part of the axillary artery, communications between the musculocutaneous and median nerves, variant formation of the brachial plexus, origination of the profunda brachii artery from the posterior circumflex humeral artery and supernumerary tendons of the abductor pollicis longus muscle. We think that such variations should be kept in mind during surgical and diagnostic procedures.

Arm↗
PubMed2003

Kondo effect in the presence of itinerant-electron ferromagnetism studied with the numerical renormalization group method.

The Kondo effect in quantum dots (QDs)-artificial magnetic impurities-attached to ferromagnetic leads is studied with the numerical renormalization group method. It is shown that the QD level is spin split due to the presence of ferromagnetic electrodes, leading to a suppression of the Kondo effect. We find that the Kondo effect can be restored by compensating this splitting with a magnetic field. Although the resulting Kondo resonance then has an unusual spin asymmetry with a reduced Kondo temperature, the ground state is still a locally screened state, describable by Fermi liquid theory and a generalized Friedel sum rule, and transport at zero temperature is spin independent.

Journal Article↗
PubMed2002

A variant of the Cannieu-Riche communication: case report.

A variant of Cannieu-Riche communication was encountered during the dissection studies. The communication was between the digital branch to the index finger and branch to the adductor pollicis muscle. Terminal communications between motor nerves may provide muscles with double motor innervation, and are important for the motor innervation of the hand, in particular the thenar muscles. This variant should be kept in mind during surgical operations, electrophysiological examinations of the hand.

Genetic Variation↗
PubMed2001

Anteroposterior diameter of the vertebral canal in cervical region: comparison of anatomical, computed tomographic, and plain film measurements.

The purpose was to compare the computed tomographic and plain film measurements with those of anatomical specimens to determine the antero-posterior diameter of the spinal canal in cervical region. Antero-posterior diameters of 75 cervical vertebral canals (15 sets of C3-C7) were measured anatomically at two different levels. Computed tomographic and plain film measurements were also obtained at the corresponding levels. Considering anatomical measurements as the gold standard, plain film and computed tomographic measurements were statistically compared. Interobserver and intraobserver differences were also evaluated. At the uppermost pedicle levels, there was no statistically significant difference between plain films and anatomical measurements, a good correlation. However, at lowermost pedicle level there was a statistically significant difference between plain films and anatomical measurements but not between tomographic and anatomical measurements. Our results suggest that plain films can accurately estimate cervical spinal canal mid-sagittal diameter at the uppermost pedicle level and be used as a first step examination for the evaluation of cervical spinal stenoses.

Anthropometry↗
PubMed2001

The canal of the posterior ampullar nerve: an important anatomic landmark in the posterior fossa transmeatal approach.

The canal of the posterior ampullar nerve is located between the inferior part of the internal acoustic meatus and ampulla of the posterior semicircular canal. It permits a more accurate localisation of the underlying labyrinth in inner-ear surgery. An anatomical and radiological study was undertaken to determine the importance the relationship between the canal and the labyrinth. Ten dry and 10 cadaveric temporal bone dissections, together with 20 high resolution CT scans of the same temporal bones were studied in an attempt to describe the anatomy of the canal of the posterior ampullar nerve. The length of the canal of the posterior ampullar nerve, the length of internal acoustic meatus, and distances from porus acusticus to the singular foramen and the transverse crest, and from the singular foramen to the vestibule and transverse crest, and from operculum to the sigmoid sinus and to the porus acusticus were measured. During the transmeatal posterior cranial fossa approach using the canal of the posterior ampullar nerve as a landmark enables more bone to be safely removed from the internal acoustic meatus thus preserving hearing.

Cadaver↗
PubMed2001

A case with subclavius posticus muscle.

During routine dissection studies, we encountered an aberrant muscle in the neck region of a 50 year-old female cadaver. The accessory muscle was on the left side. It arose from the superior angle of the scapula and lay over the brachial plexus and brachial artery then inserted to the first rib's cartilage. According to its origin and insertion, the aberrant muscle was considered to be the subclavius posticus. The accessory muscle was innervated by a branch coming from the suprascapular nerve.

Brachial Plexus↗
PubMed2001

The importance of the anatomy of the splenic artery and its branches in splenic artery embolisation.

Splenic artery embolisation can be performed preoperatively in an attempt to decrease thrombocyte destruction, or as an alternative to surgery, to obtain partial or total organ ablation. During this procedure, it is very important to deliver embolising agents distal to the origin to pancreatic branches to avoid the risk of pancreatitis. Therefore, a detailed knowledge of the anatomy of the splenic artery and its branches is required to achieve safe embolisation. The purpose of our study is to measure the average distance between the origin of the last pancreatic branch and the splenic hilum in digital angiograms and cadaver specimens.

Embolization, Therapeutic↗
PubMed2000

Tibial tubercle position and patellar height as indicators of malalignment in women with anterior knee pain.

In this study, we evaluated 70 limbs in 42 women with anterior knee pain. We investigated tibial tubercle position and patellar height indices as indicators of malalignment. Tibial tubercle rotation angles were determined by computed tomography, and patellar height indicators, Insall-Salvati, modified Insall-Salvati, Caton, and Blackburne indices were calculated on lateral knee roentgenograms. The results were compared to values obtained from 80 limbs in 40 healthy female volunteers. Tibial tubercle rotation angle was 68.1 degrees (+/-3.6) in the study group and 70.3 degrees (+/-3.8) in the control group. The difference was statistically significant (P< 0. 01). Patellar height indicators were not statistically different between the two groups. These results suggested that patellar height is not a malalignment indicator in female patients with anterior knee pain. These patients should be investigated by computed tomography to determine tibial tubercle position.

Adult↗
PubMed2000

Anatomical evaluation of the groove for the vertebral artery in the axis vertebrae for atlanto-axial transarticular screw fixation technique.

Anatomical measurements were studied on 40 dry axis vertebrae to determine the suitability of the groove for the vertebral artery for atlanto-axial transarticular screw fixation technique. We measured 13 parameters including three angular and 10 linear dimensions related to the groove of the vertebral artery, pedicle, and pars interarticularis and evaluated 80 measurements for each parameter. All measurements were done after placing a Kischner guide wire through the pedicle. We found that differences between measurements on the left and right sides of each vertebra were nonsignificant. In spite of the variability in measurements such as height, width, and median angle of the pedicle, the decline angle for instrumentation, the depth of the groove for the vertebral artery, and the internal height of the pars interarticularis, all of these had good symmetry. However, there were statistically significant differences between the sides in measurements for both the width (P=0.05) and the angle (P<0.02) of the pedicle allowing instrumentation and they did not show good symmetry. The risk of vertebral artery injury was found to be 22.5% per specimen, or 16.25% per screw inserted because the internal height of the pars interarticularis at point of fixation was </= 2.1 mm. In addition, we found that the pedicle width allowing instrumentation was not suitable in 12.5% of screws inserted because their values were </= 6 mm. When the width of the pedicle for instrumentation and the internal height of the pars interarticularis were both evaluated together, we also found that this technique would be extremely dangerous in 7.5% of specimens. In conclusion, the internal height of the pars interarticularis and the width of the pedicle for instrumentation should be evaluated together in thin CT sections preoperatively, because of the risk of vertebral artery injury in patients upon which atlanto-axial transarticular screw fixation is to be performed.

Atlanto-Axial Joint↗
PubMed2000

[Pronounced bilateral mammary hypertrophy as a rare manifestation of acute lymphatic leukemia].

A 33-year-old patient, hitherto healthy, has been admitted for clarification of bilateral mammary hypertrophy. In the course of the usual routine examination a lump of the size of a cherry was identified in the right breast. Within 6 weeks both breasts had become tight and grown symmetrically to three times their original size. A provisionary diagnosis of high malignant non-hodgkin lymphoma was made by multiple high speed needle biopsies and was later confirmed by a surgical tissue specimen of the right breast. For further classification a bone-marrow biopsy was taken from the pelvic bone and an immature acute lymphoblastic leukemia (ALL), known as preB1-ALL, diagnosed. Sonographic examination, computer tomography of the thorax and mammographical findings, as well as symptoms, outcome and differential diagnosis of a proliferative lymphatic disease with first manifestation in both breasts are presented and discussed.

Adult↗
PubMed1999

Percutaneous anterior odontoid screw fixation technique. A new instrument and a cadaveric study.

We describe a new instrument and a percutaneous technique for closed anterior fixation of odontoid fracture. The instrument which we developed consists of a telescopic tube system. This new instrument and closed fixation technique was used in six cadavers with type II odontoid fractures and to two cadavers with an intact odontoid process. Each cadaver underwent satisfactory placement of the screw to the odontoid with this technique under biplanar scopy control. After this procedure, no serious injury was found in the parapharyngeal and neurovascular areas of the necks of the cadavers, in which anatomical dissection along the track of this instrument was performed. The instrumentation and the technique as a whole is seen as reliably applicable for odontoid fracture fixation. Also, we expect to reduce operating time and hospital costs because this system is simple, easily applicable and minimally invasive.

Bone Screws↗
PubMed1997

The effect of condylectomy on extreme lateral transcondylar approach to the anterior foramen magnum.

The dorsolateral, suboccipital, transcondylar technique was used in this cadaveric study. The angle and distance measurements in the corridors were taken intradurally both superior and inferior of the foramen magnum level. In the first stage of this study, the findings which were gained from the standard lateral suboccipital approach were compared with the findings after condyle and lateral atlantal mass removal. After condylectomy, the approach to anterior foramen magnum via both corridors was found to be shorter and the lateral angle of the exposure of the anterior foramen magnum was found to be wider. The considerable shortening of the distances to the anterior foramen magnum, especially in the superior corridor, emphasises the necessity of combining standard approaches with condylectomy. In addition, it was found that after condylectomy, considerable widening of both transverse and longitudinal planes in the inferior corridor allows the surgeon greater access to work on lesions. Furthermore, the freed space between the superior corridor and the interior corridor, which was gained by condylectomy, shows that condylectomy provides a combined approach to the inferior and superior parts of the foramen magnum anteriorly.

Cadaver↗
PubMed1976

Peptide-binding macromolecules in the blood of seriously ill or mentally retarded patients.

This report describes macromolecules that bind (des-aspartic acid1)-angiotensin II, the des aspartic acid1 derivative of angiotensin I, and several biologically active and inactive analogues of these polypeptides. The macromolecules were found in the plasma of approximately 2 per cent of ambulatory adults and hospitalized children and 32 per cent of the patients at two institutions for the mentally retarded. The binding properties of these macromolecules were studied by incubating with peptides labeled with 125iodine, and separating bound from free labeled peptide using small gel filtration columns. The peptide-binding macromolecules from several patients were compared. They showed very similar specificity for a group of arginyl peptides of the des-aspartyl1-angiotensin sequence. The plasma binders differed from one another in their optimum pH and their mobility in electrophoretic fields. Those with more acid pH optima displayed more rapid electrophoretic mobility. The binders fell into two classes based on apparent molecular weight, approximately 140,000 and 250,000. Those with the higher apparent molecular weight contained a large proportion of binder that could be precipitated with antiserum to human IgA. Kinetic measurements showed that the plasma binders were somewhat heterogeneous with respect to affinity for (des-asp1)-angiotensin, with apparent association constants ranging from 10(7) to 10(8) M-1. Binding activity was labile to heat, and to treatment with pepsin or trypsin. It was inhibited by calcium, protamine, streptomycin, and some other cationic compounds. The plasma peptide binder differed in specificity and molecular weight from soluble angiotensin-binding molecules extracted from tissues, and from properties expected of a receptor for angiotensin. These macromolecules may be useful reagents for measuring (des-asp1)-angiotensins. Their presence in plasma samples may interfere with angiotensin assays in some circumstances.

Angiotensin II↗