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Biomedical subjects

C Schuster

Publications and source records attributed to C Schuster.

At least 19 recordsLinked to original sources
PubMed2006

Mutations in the ribosomal protein gene RPL10 suggest a novel modulating disease mechanism for autism.

Autism has a strong genetic background with a higher frequency of affected males suggesting involvement of X-linked genes and possibly also other factors causing the unbalanced sex ratio in the etiology of the disorder. We have identified two missense mutations in the ribosomal protein gene RPL10 located in Xq28 in two independent families with autism. We have obtained evidence that the amino-acid substitutions L206M and H213Q at the C-terminal end of RPL10 confer hypomorphism with respect to the regulation of the translation process while keeping the basic translation functions intact. This suggests the contribution of a novel, possibly modulating aberrant cellular function operative in autism. Previously, we detected high expression of RPL10 by RNA in situ hybridization in mouse hippocampus, a constituent of the brain limbic system known to be afflicted in autism. Based on these findings, we present a model for autistic disorder where a change in translational function is suggested to impact on those cognitive functions that are mediated through the limbic system.

Amino Acid Substitution↗
PubMed2006

A low level of extragalactic background light as revealed by gamma-rays from blazars.

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the 'first stars', which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the gamma-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of gamma-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources-in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to gamma-rays than previously thought.

Journal Article↗
PubMed2006

Discovery of very-high-energy gamma-rays from the Galactic Centre ridge.

The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago.

Journal Article↗
PubMed2006

[Operative treatment of proximal humeral fractures with helix wire].

BACKGROUND: Between 1 January 2000 and 31 December 2002, a total of 50 patients with a dislocated or unstable fracture of the proximal humerus were treated surgically with a titanium helix wire introduced retrogradely into the medullary cavity. MATERIAL AND METHODS: Fracture classification showed 8 cases of a two-fragment fracture, 32 cases of a three-fragment fracture, and 10 cases of a so-called four-fragment fracture. A retrospective radiographic and medical review of all 50 patients showed postoperative complications in 24% of the cases; in 8 cases (16%) secondary loss of retention occurred with consecutive projection of the helix wires into the subacromial joint space. There were two cases each (4%) of perforation of the helix wire into the joint space without loss of retention and fracture dehiscence because of a blocking mechanism by the helix wire in the subcapital fracture gap. The postoperative revision rate was 18% (9/50) as a result. Of 50 patients with a titanium helix wire, 38 (76%) were reviewed after an average of 23 months (12-31). Radiologically partial necrosis of the head of the humerus was seen in two patients and there was necrosis of the head of the humerus with pseudarthrosis in one patient, which had a negative effect on the Constant score. RESULTS: Because of a change of procedure (n=5) and intercurrent deaths (n=5) only 2 of 12 patients, in whom complications had occurred postoperatively, could be followed up clinically; the results of the follow-up are sure to be distorted by this selection effect. Of 38 patients, 32 (84%) showed very good to good results functionally; the average Constant score was 74 points and the average age- and sex-specific corrected score was 92%. DISCUSSION: Thus, the procedure does not achieve better functional results compared to other rigid and semirigid internal fixation methods while it has a high complication and revision rate compared to other rigid and semirigid internal fixation methods. Moreover, early functional treatment is not possible so that the titanium helix wire represents a retention aid rather than stable internal fixation. Overall we cannot recommend the procedure for the operative management of proximal humerus fractures further and have abandoned it ourselves.

Adult↗
PubMed2006

Vascular pattern of the palms--a clinical feature of atopic skin diathesis.

BACKGROUND: Atopic skin diathesis is a clinical term to describe skin atopics with previous, present or future atopic eczema/dermatitis syndrome (AEDS). In clinical practice, an unequivocal assessment of atopic skin diathesis in non-eczematous patients may be difficult. The majority of the known clinical features included in diagnostic scores are characteristic, but not specific markers of atopy. Especially, the vasoreactivity of atopic skin is disturbed. This is manifested by white dermographism, an irregular vascular response to thermal stimuli, and paradoxic skin reactions to histamine, cholinergic agents, and nicotinates. OBJECTIVE: The aims of our study were to investigate the clinical morphology of palmar vascular reactions in skin atopic and non-atopic individuals, and to determine whether this abnormal vascular reaction is more pronounced in skin atopic individuals. METHODS: Forty persons, 20 of them skin atopics, assessed by the Erlangen Atopy Score and an elevated serum IgE level (>150 U/ml), were included in a prospective single-centre study. Standardized digital photographs of the palms were presented in a blinded manner to five dermatologists in random order by means of the computerized imaging analysis system KS400 3.0. RESULTS: Evaluation of the original rgb (red, green, blue) color images and modified gray-level images showed that a pronounced reticular pattern of erythema of the palms was significantly (P < 0.0001) more common in skin atopics (72% and 69.6%, respectively). CONCLUSION: The gross vascular pattern of the palm might be an additional diagnostic feature of atopy, and further studies are needed to establish its exact prevalence.

Dermatitis, Atopic↗
PubMed2005

Discovery of very high energy gamma rays associated with an x-ray binary.

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Journal Article↗
PubMed2005

A new population of very high energy gamma-ray sources in the Milky Way.

Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (HESS) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or x-ray counterpart and may be representative of a new class of "dark" nucleonic cosmic ray sources.

Journal Article↗
PubMed2005

Absence of contact sensitization to Aloe vera (L.) Burm. f.

Aloe vera has been used as a cosmetic and medical remedy since ancient times and has gained increasing popularity in recent years. Despite its widespread use, reports of allergic reactions are rare. We patch tested 702 consecutive patients with an oily extract from the leaves, Aloe pulvis from the entire plant and concentrated Aloe vera gel. A specially designed questionnaire was used for the use of Aloe vera, reasons and location of application, adverse reactions, occupation, hobbies and atopy. None of the subjects showed any reaction to one of the preparations. 2 components of the plant have to be distinguished: the bark of the leaves contains anthrachinones with pro-peristaltic and potential antibiotic and anticancer properties. Constraints have been imposed due to their considerable toxic potential. Today, mostly the Aloe gel from the center of the leaves is processed. It almost exclusively consists of carbohydrates to which also many medical effects have been attributed. Carbohydrates are not likely to induce contact sensitization, which might explain the outcome of our study. However, this does not justify unrestrained promotion of Aloe products, as scientific studies investigating the claims on its constitutional effects are few in number, and the majority of them have been unable to diminish the intuitive scepticism against miracle cures, like Aloe seems to be.

Allergens↗
PubMed2005

The human MT1 melatonin receptor stimulates cAMP production in the human neuroblastoma cell line SH-SY5Y cells via a calcium-calmodulin signal transduction pathway.

Melatonin regulates circadian and seasonal physiology via melatonin receptors expressed in the brain. However, little is known about the signal transduction mechanisms that mediate the action of melatonin in neuronal cells. To begin to address this issue, we expressed the human MT(1) receptor in the human neuroblastoma SH-SY5Y cell line. In this cell line, melatonin acutely stimulated cAMP synthesis through a calcium-calmodulin dependent pathway. This stimulatory effect was independent of an interaction with G(i) or G(s) G proteins and dependent upon internal calcium stores. Melatonin also potentiated forskolin-activated cAMP synthesis. Differentiation of the neuroblastoma cells with retinoic acid to the neuronal phenotype did not alter the ability of melatonin to acutely stimulate cAMP. These data may be relevant to the neuronal action of melatonin and highlight the importance of the cellular context of expression of melatonin and other G protein-coupled receptors.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed2004

High-energy particle acceleration in the shell of a supernova remnant.

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Journal Article↗
PubMed2003

HCV core, NS3, NS5A and NS5B proteins modulate cell proliferation independently from p53 expression in hepatocarcinoma cell lines.

Several reports have shown that activity and/or expression of p53 can be modulated by Hepatitis C virus (HCV) proteins and may interfere with normal regulation of cell growth. In order to understand the relationship between p53 function and HCV proteins expression, we have investigated potential effects of the core, NS3, NS5A and NS5B proteins on Huh-7 (p53 +/+) and Hep3B (p53 -/-) cell proliferation. The effect of HCV proteins transiently expressed after recombinant-adenoviral infection was analyzed by Western blot, crystal violet and propidium iodide staining. Expression of the core, NS3, NS5A or NS5B proteins inhibited cell proliferation and blocked both cell lines in the G2/M phase of the cell cycle. c-myc and p53 expression were respectively induced and increased in Huh-7 cells only following expression of the Core protein. No expression of p21(waf1/cip1) could be detected and expression of cyclin A, cdk2 and p27(Kip1) were independent of HCV protein's expression. Our results show that the effect of core, NS3, NS5A and NS5B on cell proliferation is independent of p53 expression and that only the Core protein, induces the expression of both c-myc and p53.

Blotting, Western↗
PubMed2003

Sensitization: a mechanism for melatonin action in the pars tuberalis.

Sensitization of adenylate cyclase is a recently discovered phenomenon. Melatonin can induce a sensitized response of adenylate cyclase in ovine pars tuberalis cells where the receptor for melatonin is endogenously expressed. Although the mechanism is not fully understood, sensitization of adenylate cyclase may be an important part of the mechanism by which melatonin encodes daylength in the pars tuberalis of sheep and other animals. We used this as a hypothesis to search for a natural ligand that would activate adenylate cyclase in ovine pars tuberalis cells. The approach revealed pituitary adenylate cyclase activating polypeptide to be an indirect activator of adenylate cyclase in the ovine pars tuberalis. We discuss this in relation to the mechanism and importance of sensitization to the function to the pars tuberalis.

Adenylyl Cyclases↗
PubMed2001

Adolescent marijuana use and adult occupational attainment: a longitudinal study from age 18 to 28.

This report uses data from a nationally representative longitudinal sample to examine the relationship of marijuana use by high school seniors to occupational attainment 10 years later. Analyses were conducted separately by gender, with and without controlling for other variables. Control variables, all measured when respondents were seniors, were: academic performance, educational aspirations, and occupational aspirations. Results indicate that the influence of marijuana use on occupational attainment is considerably different for males and females.

Adolescent↗
PubMed2001

The circadian clock, light/dark cycle and melatonin are differentially involved in the expression of daily and photoperiodic variations in mt(1) melatonin receptors in the Siberian and Syrian hamsters.

Mechanisms underlying the daily and photoperiodic variations in mt(1) melatonin receptors were investigated in the pars tuberalis (PT) and suprachiasmatic nuclei (SCN) of Siberian and Syrian hamsters. Whatever its daily profile, melatonin receptor density was strongly increased in both structures and species after constant light exposure or pinealectomy, and decreased after a single melatonin injection, indicating melatonin involvement in the daily regulation of the receptor protein. This was confirmed by a strong inverse correlation between melatonin binding capacity and plasma melatonin concentration. In contrast, regulation of mt(1) mRNA appeared more complex. The circadian clock, the light/dark cycle and melatonin are all implicated in mt(1) gene daily fluctuations, but the extent of their involvement depends upon the structure and the species studied. The photoperiodic decrease in melatonin receptor density observed in short photoperiod (PT of the two hamster species and Syrian hamster SCN) seems to be the consequence of a long-term mt(1) gene repression induced by the lengthening of the melatonin peak. Altogether, these results show that during daily variations, mt(1) melatonin receptor mRNA and protein are differentially regulated, while at the photoperiodic level, the mt(1) protein status depends on mRNA transcription.

Animals↗
PubMed2000

[Custom-made knee endoprosthetics using subtraction data of 3-dimensional CT scans. A new approach].

A new method is presented which allows the construction and implantation of highly precise custom-made endoprostheses for knee joints. The procedure is based on a computer-aided subtraction process of three-dimensional CT data. Using the differences of the CT scans, the endprosthetic components are modelled by means of a newly developed software package. The implants are manufactured by CNC machines and stereolithography. The method enables the surgeon to reduce bone resections and ensures an exact profile of the bone-implant interface. Incorrect positioning will be avoided and the implantation process can be performed more easily while the size of the operative approach will be minimized. Better postoperative kinematics and reduction of shearing effects will lead to better results in the long run. The procedure offers a series of new possibilities to optimize monocondylar and bicondylar knee joint endoprostheses.

Arthroplasty, Replacement, Knee↗