Search PubMed⌕ Search

Biomedical subjects

A Schilling

Publications and source records attributed to A Schilling.

At least 19 recordsLinked to original sources
PubMed2006

A comparison of the head and cervical posture between the self-balanced position and the Frankfurt method.

Head and cervical posture evaluation has been a concern for many years, not only because of the purported relationship that exists between head and cervical posture in the presence of temporomandibular disorders, neck pain and headache, but also because of the biomechanical relationship between the head and cervical spine and dentofacial structures. Many methods have been suggested in an attempt to establish the best way to evaluate the position of the head using teleradiographs and cephalometric analysis. However, there is still no agreement as to which procedure is the best. The objective of this study was to evaluate the differences that exist between craniocervical measurements in lateral teleradiographs when comparing the position of the head in the self-balanced position to the position of the head using the Frankfurt method (Frankfurt plane parallel to the floor). Sixty-eight subjects who sought dental treatment in community health centres in Talca, Chile participated in this study. Rocabado analysis was used to measure the craniocervical variables. The Cobb analysis was used to measure cervical lordosis. A paired student t-test was used to evaluate the differences between both procedures, using an alpha of 0.05 and a power of 0.90. The use of the cephalostat changed only the craniocervical angle (P < 0.001). However, this change was minimal. No changes related to gender and age were found. More studies are needed to determine the variation between different procedures and to define a good procedure for evaluating head posture.

Adolescent↗
PubMed2005

Social inhibition of seasonal fattening in wild and captive gray mouse lemurs.

Due to their differential reproductive investment, males and females often exhibit high differences in energy management. The main hypothesis tested in this study is that short photoperiod-induced fattening in the small primate Microcebus murinus is strongly affected by social cues. Short photoperiod-induced changes in body mass, lean mass and thyroid hormone T4 plasma levels measurements were investigated in wild and captive animals. Individual housing showed that both males and females are able to fatten. Fattening was associated with a slight increase of lean mass that reached a plateau after 3 weeks. In contrast, social grouping led to an inhibition of fattening, even when direct interactions were prevented. This social inhibition was mainly observed in males, especially when housed with females, suggesting that their low weight gain in the wild is due to female dominance. Accordingly, wild and captive animals of both sexes exhibited a decrease in T4 plasma levels, revealing a decrease in energy expenditure. Moreover, testis recrudescence observed after 20 weeks of short photoperiod exposure did not lead to any inhibition of fattening, indicating that males take advantage of female hibernation late in the dry season to fatten and use their fat reserves for the mating competition. Therefore, seasonal fattening may be used by females to prepare for hibernation and by males to prepare for the mating competition.

Analysis of Variance↗
PubMed2005

[Sensor-based detection of skull positioning for image-guided cranial navigation under free head mobility].

PURPOSE: Although computer- and image-guided surgical procedures are an improvement of frame-guided stereotaxy, many navigation systems still require rigid fixation of the patient's head throughout the operation. This study describes the clinical application of a technical modification that enables cranial navigation with "free head mobility" using CT and MR images as well as the calculated 3-D reconstruction models. MATERIAL AND METHODS: A sensor-based electromagnetic neuronavigation system was expanded to allow the localization and position monitoring of several sensors within an electromagnetic field. One of these sensors was attached to a dental splint as an additional reference (DRF = dynamic reference frame). Thus, it was possible to determine the position of the sensor-guiding surgical instruments and to record the slightest movement of the cranium as well. This information was then used to continuously adapt the position of the imaging plane and the resultant calculated 3-D reconstructions to the actual position of the cranium. RESULTS: The clinical application of the DRF was tested for different neurosurgical procedures. They included image-guided biopsies and endoscopic interventions using MRI data, transnasal accesses to the base of the skull using CT data and surgical removal of multilocular metastases using data from both imaging modalities. Intracranial target reference points as well as those on the skull were found with a high accuracy to the initial measurement position after arbitrary movement of the patient's head. Thus, navigation was also possible without rigid fixation of the head because of the continuous adaptation of the imaging data on the change in position of the patient's head. CONCLUSION: Based on these first test results, a high clinical potential for DRF application in cranial navigation is to be expected. The aim of DRF is to dispense with the rigid fixation of the patient's head. This increases the application scope of image-guided navigation procedures to include, for example, any bioptic or endoscopic intervention, in which rigid pin fixation of the cranium is not required or desired. For all other procedures, continuous position monitoring by DRF ensures automatic correction of imaging data with mechanical alteration of the head position.

Brain Diseases↗
PubMed2005

Resection of multiple lung metastases--where are the limits?

Multiple lung metastases present a serious and challenging problem with increasing incidence for thoracic surgeons. In the lung metastasis management a significant role belongs to laser lung-parenchyma-saving resection. This parenchyma saving technique allows a removal of significant higher number of lung nodules in comparison to conventional techniques (stapler, clamp resection). Performing the lung metastasectomy by this manner, the only remaining question is the limitation of this technique. In this retrospective study, the results after Nd:YAG Laser (1318 nm, 40 Watt) interventions are being presented, the limitations of this technique are being discussed (Tab. 3, Fig. 4, Ref. 9).

Adult↗
PubMed2004

In vivo 1H magnetic resonance spectroscopy of rat brain after valproate administration.

Previous studies have shown that valproate is detectable in vitro by 1H magnetic resonance spectroscopy (MRS) at 1.5 T, whereas in patients on valproate monotherapy, no significant dose-dependent valproate signal could be seen. To investigate whether an increased signal-to-noise ratio as provided by higher valproate doses and increased magnetic field strength would enable detection of valproate in vivo, six Wistar rats were examined using volume-selective 1H MRS at 2.34 T. The spectra were analyzed by fitting a linear superposition of the basis spectra of valproate, brain metabolites, and simulated lipid signals. The analysis revealed no significant signal contributions after valproate administration of up to 330 mg/kg body weight. To analyze how underlying mechanisms, such as potential drug interactions with macromolecules, may affect the valproate signal, additional in vitro spectra of valproate were measured before and after adding albumin. The spectra exhibited a strong decrease of the valproate signal with increasing albumin concentration. The results support the hypothesis that in vivo valproate is bound to a high degree to macromolecules and will therefore not be detectable by 1H MRS.

Animals↗
PubMed2004

Improved outcome of zygomycosis in patients with hematological diseases?

Zygomycosis is an opportunistic fungal infection that is increasingly reported in hematological patients. We describe 2 cases of successfully treated rhino-cerebral zygomycosis and give an overview of 120 patients from the literature with underlying hematological or oncological disorders. These data document the improved survival in sinus (15/17 patients surviving) and cutaneous (6/9 patients surviving) disease. Hematological patients with pulmonary (9/30 patients surviving) or disseminated (4/38 patients surviving) zygomycosis still have a poor prognosis. The clinical course of sinus-orbital involvement (4/11 patients surviving) follows sinus-cerebral (2/3 patients surviving) or cerebral (3/6 patients surviving) disease. Besides deoxycholate amphotericin B (AmB) (24/62 patients surviving), patients seem to benefit from liposomal amphotericin B (L-AmB) (10/16 patients surviving) or sequential AmB/L-AmB treatment (6/8 patients surviving). Alternative treatment options lead only in a few patients to success.

Adult↗
PubMed2003

[Septic encephalopathy. Diagnosis und therapy].

23% of all septic patients develop septic encephalopathy which is associated with an increased mortality rate. Symptoms such as agitation, confusion and disorientation ranging from stupor to coma often develop in early sepsis. Severe hypotension is significantly associated with the development of septic encephalopathy. Several other factors which may play a role are also discussed: effects of inflammatory mediators on the brain, inadequate cerebral perfusion pressure, blood-brain barrier derangements, disturbances of the cerebral microcirculation, cerebral ischemia e.g. due to hypocapnia,metabolic changes, altered amino acid levels, transmitter imbalances, liver insufficiency, multiple organ failure and infections of the CNS, respectively. Compared to patients with an isolated infection,patients in septic shock have increased levels of aromatic amino acids such as phenylalanine and tryptophan in the plasma and brain as well as decreased levels of branched chain amino acids. Patients who died had higher levels of aromatic amino acids than the survivors. The correlation between aromatic amino acids and the APACHE II score was significant. The tryptophan metabolite quinolinic acid which can be synthesized in activated macrophages could act as an excitatory transmitter on the N-methyl-D-aspartate (NMDA) -receptor. Observations from experimental models indicate that activated NMDA receptors activate the neuronal isoform of the NO-synthase and other calcium dependent enzymes. This releases free radicals which may damage the DNA and activate the nuclear enzyme Poly-ADP-ribose-synthetase (PARS), resulting in energy depletion and cell death. Sepsis is the main cause of metabolic encephalopathies in critically ill patients. The differential diagnoses include hepatic, renal,hypoxic-ischemic or cardiovascular encephalopathies as well as encephalopathies,metabolic disorders and organ dysfunctions of other origin. Therapeutic interventions are numerous,however, so far only investigated in few controlled studies. The primary therapeutic goal is to maintain an adequate perfusion pressure and to prevent hypoxia and hypocapnia. Although the infusion of branched chain amino acids is controversial, experimental investigations demonstrated improvements improvements in an animal model with septic encephalopathy. Further investigations with respect to glutamate receptor antagonists, new radical scavengers, NO- and PARS-inhibitors may show whether these substances are suitable for the prophylaxis or early therapy of septic encephalopathy.

Animals↗
PubMed2003

Clinical evaluation of a new intracranial pressure monitoring device.

BACKGROUND: Continuous monitoring of intracranial pressure (ICP) still plays a key role in the management of patients at risk from intracranial hypertension. Numerous ICP-measuring devices are available. The aim of the present study was to investigate the clinical characteristics and the magnetic resonance imaging (MRI) compatibility of the recently developed Neurovent-P(REHAU AG+CO, REHAU, Germany) ICP monitoring device. METHOD: In a prospective two-center study, a total of 98 patients with severe head injury, subarachnoid haemorrhage, intracerebral haemorrhage, and non-traumatic brain edema underwent intraparenchymal monitoring of ICP using the Neurovent-P. A control group comprising 50 patients underwent implantation of the Camino-OLM-110-4B ICP monitor. The zero drift of the probes was determined before and after the ICP recording period. Technical and medical complications were documented. The MRI compatibility of the Neurovent-P ICP probe was investigated by evaluating artifacts caused by the probe, probe function and temperature changes during MRI, and probe movement caused by the magnetic field. FINDINGS: The mean zero drift was 0.2+/-0.41 mmHg (maximum 3 mmHg) for the Neurovent-P ICP probes and 0.4+/-0.57 mmHg (maximum 12 mmHg) for the Camino-OLM-110-4B ICP probes. No significant correlation was identified between the extent of zero drift following the removal of the probes and the length of monitoring. Intraparenchymal haemorrhage spatially related to the probe occurred in 1 out of 50 (2%) patients with a Camino-OLM-110-4B probe and in 1 out of 98 (1%) with a Neurovent-P. Damage of the probe due to kinking or overextension of the cable or glass fiber occurred in 4 of the 50 (8%) Camino-OLM-110-4B ICP probes and in 5 of the 98 (5%) Neurovent-P probes. On T2-weighted MR images, the Neurovent-P ICP probe induced only small artifacts with very good discrimination of the surrounding tissue. On T1-weighted MR images, there was a good imaging quality but artifact-related local disturbances in signal occurred. There was no temperature change in the Neurovent-P probe and in the surrounding brain tissue during MR imaging. INTERPRETATION: The Neurovent-P ICP measuring system is a safe and reliable tool for ICP monitoring. Handling of the Neurovent-P system is safe when performed properly.

Adolescent↗
PubMed2003

Melatonin and methimazole mimic short-day-induced fattening in gray mouse lemurs.

Short-day-induced fattening was investigated in the small nocturnal primate Microcebus murinus. Animals were either transferred from long photoperiod (LP) to short photoperiod (SP) or maintained in LP and submitted to various treatments. Animals fed daily on 40 microg of melatonin (MEL) at two different times showed a significant increase in body mass compared to LP-exposed animals. This weight gain was more marked in animals fed with MEL 2 h before night onset, suggesting a critical period around the first hours of the night. The MEL-induced fattening was associated with an increase in food intake and a decrease in plasma thyroxin (T4) levels. On the other hand, a decrease in T4 plasma levels induced by two doses of methimazole (MET) led to either an increase (3 mg/day) or a decrease (10 mg/day) of body mass, suggesting a role of thyroid hormones in the photoperiodic regulation of body mass. The MET-induced fattening did not involve any change in food intake. These findings suggest that autumn fattening in the gray mouse lemur proceeds from two distinct mechanisms. First, an increase of food intake may result in the SP-induced increase in MEL secretion. Second, a decrease of energy expenditure may be due to the MEL-induced hypothyroidism.

Adipose Tissue↗
PubMed2003

An unrandomized prospective comparison of urinary continence, bowel symptoms and the need for further procedures in patients with and with no adjuvant radiation after radical prostatectomy.

OBJECTIVE: To prospectively assess, using a questionnaire-based study, the relative differences and changes in urinary continence and bowel symptoms, and the need for further surgery, within the first year after radical retropubic prostatectomy (RRP) in patients with and with no adjuvant radiotherapy (aRT). PATIENTS AND METHODS: The study included 96 men with clinically organ-confined adenocarcinoma of the prostate who underwent RRP between March 1998 and June 1999. A subset of 36 patients was recommended aRT of the prostatic fossa (median dose 54 Gy) because of positive surgical margins and/or seminal vesicle involvement. Using a mailed questionnaire all patients were prospectively assessed at 4-month intervals for the first year after RRP. RESULTS: Valid data were analysed from 83 patients (overall response rate 86%), of whom 30 (36%) had received aRT. At 4 months a significantly lower proportion used no pads and significantly more used 1 pad/day in the aRT than in the RRP group (both P < 0.05). Eight and 12 months after RRP there was no statistically significant difference between the groups in urinary incontinence. However, 53% of men in the aRT group had stool urgency and 13% reported fecal incontinence at 4 months, compared with 1.9% and none (both P < 0.01) of the RRP group. At 1 year after RRP bowel symptoms and fecal continence improved in the aRT group and there was no significant difference for these symptoms between the groups. Starting aRT early (< or = 12 weeks after RP) or late (> 12 weeks) had no significant effect on urinary continence, bowel symptoms and fecal incontinence. Apart from dilatation of urethral strictures in one patient in each group, no further procedures were reported during the follow-up. CONCLUSION: A moderate dose of aRT after RRP had a temporary effect on subjective urinary continence at 4 months but not at 8 and 12 months. More patients receiving aRT reported significant bowel symptoms at 4 and 8 months than those with RRP only, but at 1 year most of these symptoms had resolved and there were no significant differences between the groups.

Adenocarcinoma↗
PubMed2002

Dissemination of the AHCPR clinical practice guideline in community health centres.

OBJECTIVE: To evaluate dissemination of the Agency for Health Care Policy and Research (AHCPR) Smoking cessation clinical practice guideline in community health centres. DESIGN: Pre- and post-trial. SETTING: Fourteen community health centres in Rhode Island. SUBJECTS: Provider performance was assessed with 1798 and 1591 patient contacts, in pre-post cross sectional consecutive samples, respectively, and 891 contacts at one year follow up. INTERVENTIONS: Three, one hour on-site provider training sessions, on review of effective tobacco interventions, use of office systems, and tobacco counselling skill building. OUTCOME MEASURES: Chart documentation of four A's (Ask, Advise, Assist, and Arrange follow up) at most recent primary care visit. RESULTS: While average performance rates increased for Ask and Advise (from 30% to 44%, and 19% to 26%, pre-post, respectively), significant increases were found only for some visit types, with further differences by patient sex. There were significant increases for Ask for all except obstetric/gynaecological (ob/gyn) visit types. Patients at yearly physicals and first visits were more likely to be asked at all time points, while males were more likely to be asked at acute visits than were females. There were no significant increases for Advise, Assist, and Arrange across time, although female patients showed a differential increase in Advise post-training. Advise was significantly more likely in yearly physicals and first visits, and less likely in ob/gyn visits, at all time points. CONCLUSIONS: This guideline dissemination effort resulted in quite different provider counselling rates across patient sexes, and visit types. Guideline implementation may require more sustained efforts, with multiple strategies, which are reinforced at higher policy levels, to more fully integrate tobacco interventions into routine primary care practice with all patients who smoke.

Adult↗
PubMed2001

An unusual phase transition to a second liquid vortex phase in the superconductor YBa2Cu3O7.

A magnetic field penetrates a superconductor through an array of 'vortices', each of which carries one quantum of flux that is surrounded by a circulating supercurrent. In this vortex state, the resistivity is determined by the dynamical properties of the vortex 'matter'. For the high-temperature copper oxide superconductors (see ref.1 for a theoretical review), the vortex phase can be a 'solid', in which the vortices are pinned, but the solid can 'melt' into a 'liquid' phase, in which their mobility gives rise to a finite resistance. (This melting phenomenon is also believed to occur in conventional superconductors, but in an experimentally inaccessible part of the phase diagram.) For the case of YBa2Cu3O7, there are indications of the existence of a critical point, at which the character of the melting changes. But neither the thermodynamic nature of the melting, nor the phase diagram in the vicinity of the critical point, has been well established. Here we report measurements of specific heat and magnetization that determine the phase diagram in this material to 26 T, well above the critical point. Our results reveal the presence of a reversible second-order transition above the critical point. An unusual feature of this transition-namely, that the high-temperature phase is the less symmetric in the sense of the Landau theory-is in accord with theoretical predictions of a transition to a second vortex-liquid phase.

Journal Article↗
PubMed2001

Comparative distribution of mRNA encoding the growth hormone secretagogue-receptor (GHS-R) in Microcebus murinus (Primate, lemurian) and rat forebrain and pituitary.

The forebrain and pituitary sites of synthesis of growth hormone secretagogue-receptor mRNA were identified in four adult lemurs (Microcebus murinus) by in situ hybridisation performed with a radiolabeled cRNA probe transcribed from human Growth Hormone Secretagogue-Receptor cDNA. The cRNA sense and antisense probes were hybridised to cryostat sections containing structures extending from the rostral hypothalamus to its caudal limit as defined by the mammillary bodies. The pituitary gland and areas adjacent to the hypothalamus were also analyzed. For comparative purposes, sections from five adult rats containing these structures were hybridised with the same probes. The results point to a widespread distribution of Growth Hormone Secretagogue-Receptor mRNA in the hypothalamus, hippocampal formation, and cerebellar cortex of both lemurs and rats. As in the rat, specific hybridisation was particularly dense in the arcuate nucleus. Significant species differences were observed in the periventricular nucleus, the ventromedial nucleus, the lateral hypothalamic area, and the pituitary gland. In contrast to the rat, the lemur exhibited marked labelling in the infundibular nucleus, the periventricular nucleus and the pars tuberalis of the pituitary gland, whereas no labeling was detectable in the ventromedial nucleus and the lateral hypothalamic area. These results are discussed in terms of difference between the control of growth hormone secretion, feeding behaviour and seasonal rhythmicity among murine species and primates.

Animals↗
PubMed2001

Volume-selective proton MR spectroscopy for in-vitro quantification of anticonvulsants.

Administration of anticonvulsant drugs is clinically monitored by checking seizure frequency and by determining the serum concentration of the drug. In a few reports, drug concentrations in brain parenchyma have been determined using ex vivo techniques. Little is known about the in vivo concentration in the brain parenchyma. Our goals were to characterise the NMR spectra of the anticonvulsants at therapeutic concentrations, to determine the minimum detectable concentrations, and to quantify the drugs noninvasively. Volume-selective 1H-MR spectroscopy (MRS) was performed under standard clinical conditions using a single-voxel STEAM (stimulated-echo acquisition mode) sequence at 1.5 T. Spectra of the anticonvulsants carbamazepine, phenobarbital, phenytoin and valproate were acquired in vitro in hydrous solutions at increasing dilution. Phenytoin, phenobarbital and valproate were detectable below maximum therapeutic serum concentrations. Within therapeutic ranges, there was good agreement between concentrations determined by 1H-MRS and those by standard fluorescence polarisation immunoassay. Due to the absence of signals of brain metabolites, the aromatic protons of phenobarbital, phenytoin and carbamazepine, with resonance lines around 7.4 ppm, allow the drugs to be detected. Valproate, with two resonances around 1.2 ppm, should be differentiable from potential brain metabolites using nonlinear analysis of the brain spectrum. Volume-selective 1H-MRS is therefore expected to be able to monitor anticonvulsant therapy in vivo.

Anticonvulsants↗
PubMed2001

Artificially accelerated aging by shortened photoperiod alters early gene expression (Fos) in the suprachiasmatic nucleus and sulfatoxymelatonin excretion in a small primate, Microcebus murinus.

In mammals, a number of anatomical and functional changes occur in the circadian timing system with aging. In certain species, aging can be modified by various factors which induce a number of pathological changes. In a small primate, the gray mouse lemur (Microcebus murinus), long-term acceleration of seasonal rhythms by exposing the animals to a shortened photoperiodic regime (up to 2.5 times the natural photoperiodic regime) alters longevity, based on survival curves and morphological changes. This provides a model for challenging the idea that modifications of the circadian pacemaker are related to chronological (years) versus biological (photoperiodic cycles) age. To assess the effect of aging and accelerated aging on the circadian pacemaker of this primate, we measured body weight variations, the daily rhythm in urine 6-sulfatoxymelatonin and the light-induced expression of the immediate early gene (Fos) in the suprachiasmatic nucleus of mouse lemurs that had been exposed to different photoperiodic cycles. Urine samples were collected throughout the day and urine 6-sulfatoxymelatonin levels were measured by radioimmunoassay. Light-induced Fos expression in the suprachiasmatic nucleus was studied by exposing the animals to a 15-min monochromatic pulse of light (500 nm) at saturating or sub-saturating levels of irradiance (10(11) or 10(14) photons/cm(2)/s) during the dark phase. The classical pattern of 6-sulfatoxymelatonin excretion was significantly altered in aged mouse lemurs which failed to show a nocturnal peak. Fos expression following exposure to low levels of irradiance was reduced by 88% in the suprachiasmatic nucleus of aged mouse lemurs. Exposure to higher irradiance levels showed similar results, with a reduction of 66% in Fos expression in the aged animals. Animals subjected to artificially accelerated aging demonstrated the same alterations in melatonin production and Fos response to light as animals that had been maintained in a routine photoperiodic cycle. Our data indicate that there are dramatic changes in melatonin production and in the cellular response to photic input in the suprachiasmatic nucleus of aged mouse lemurs, and that these alterations depend on the number of expressed seasonal cycles rather than on a fixed chronological age. These results provide new insights into the mechanisms underlying artificial accelerated aging at the level of the molecular mechanisms of the biological clock.

Aging↗
PubMed2001

Albedo-enhanced maximum UV irradiance--measured on surfaces oriented normal to the sun.

UV radiation measured on normal-to-the-sun-oriented surfaces can show significantly higher global UV irradiance values compared to measurements on horizontal receivers. The direct component is amplified by the inverse cosine of the zenith angle, but over surfaces with high local albedo this accounts for only about half of the signal rise of global irradiance. The signal rise of the diffuse component, however, is strongly related to local albedo and solar elevation, which is demonstrated by 2 years of measurements of direct, diffuse, global, reflected and global normal-to-the-sun erythemal effective UV irradiance (UVery). Global UVery signal rises, on normal-to-the-sun-oriented versus horizontal receivers, of up to 65% were measured on fresh snow and solar elevation angles below 30 degrees. An empirical expression has been deduced from the measurements relating the ratio of normal-to-the-sun versus horizontal measurements of global UVery to surface albedo and solar elevation. This allows one to calculate the maximum global UVery irradiance levels which are to be expected on normal-to-the-sun-oriented surfaces with respect to horizontal measurements or model calculations.

Journal Article↗
PubMed2000

Intracranial haemorrhage following lumbar myelography: case report and review of the literature.

We describe a subacute intracranial subdural haematoma following lumbar myelography. This rare but potentially life-threatening complication has been reported both after lumbar myelography and following lumbar puncture for spinal anaesthesia. We review 16 previously reported cases of intracranial haemorrhage following lumbar myelography, and discuss the pathogenesis. In all reported cases post-puncture headache was the leading symptom and should therefore be regarded as a warning sign.

Cerebral Angiography↗