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Biomedical subjects

A Enders

Publications and source records attributed to A Enders.

16 recordsLinked to original sources
PubMed2006

Magic alkali-fullerene compound clusters of extreme thermal stability.

The thermal stability of free pure C60-, as well as C60-alkali, and -alkaline-earth metal compound clusters is investigated. We find that small (C60)m-clusters (m<or=6) decay at comparatively low temperatures below 400 K, as a consequence of weak intermolecular van der Waals interaction. Adding barium or potassium to the clusters dramatically increases the decay temperatures for "magic" configurations of (C60)mBa(2m-1) and (C60)mK(2m), which reach values as high as 1780 K. Contrary to common belief, the superstable compound clusters are not characterized by filled geometrical or electronic shells. Density functional calculations show that the delicate interplay of ionic (K, Ba) and covalent (Ba) interaction between C60 and the metal atoms, on the one hand, and entropic contributions to the Gibbs free energy, on the other hand, determine the unusual stability.

Journal Article↗
PubMed2004

Development of granulomatous common variable immunodeficiency subsequent to infection with Toxoplasma gondii.

Common variable immunodeficiency (CVID) is a heterogeneous immunodeficiency that is accompanied by granulomatous lesions in 5-10% of cases. Why some patients develop granulomatous disease remains unclear. Here we describe a 12-year-old previously healthy girl who presented with pancytopenia and granulomatous lymphoproliferation subsequent to infection with Toxoplasma gondii. Loosely arranged non-fibrosing granulomas were observed in the liver, lymph nodes and lung, but no Toxoplasma tachyzoites could be demonstrated and polymerase chain reaction (PCR) and culture were negative for Toxoplasma and a wide range of other pathogens. While the patient had a normal peripheral B cell status at presentation, the development of CVID could be observed during the following months, leading to a loss of memory B cells. This was accompanied by an increasingly activated CD4(+) T cell compartment and high serum levels of angiotensin-converting enzyme (ACE), tumour necrosis factor (TNF) and sCD25. Steroid therapy reduced pancytopenia, granulomatous lymphoproliferation and cytokine elevations, but did not improve the B cell status. This is the first report of an association of Toxoplasma infection with granulomatous CVID and provides one of the rare examples where the onset of CVID could be documented subsequent to an infectious disease.

Acute Disease↗
PubMed2003

Temperature dependence of the surface anisotropy of Fe ultrathin films on Cu(001).

We report an experimental approach to separate temperature dependent reversible and irreversible contributions to the perpendicular magnetic anisotropy of Fe films grown at low temperatures on Cu(001) substrates. The surface anisotropy K(S)(T) is found to decrease linearly with temperature, causing a thermally induced spin reorientation into the plane. The irreversible shift of the spin reorientation transition and the coercivity of the iron films are directly correlated to the increasing Fe island size during annealing. The increased coercivity is discussed in terms of domain wall energy inhomogeneities provided by the islands.

Journal Article↗
PubMed2003

T-cell-depleted peripheral blood stem cell transplantation for alpha-mannosidosis.

Alpha-mannosidosis (alpha-mannosidosis) is a lysosomal storage disease characterized by accumulation of oligosaccharides in various tissues leading to symptoms such as coarse facial features, dysostosis multiplex, hearing disabilities, mental developmental delay and skeletal involvement (dysostosis multiplex). Without treatment, the severe infantile onset form of this autosomal recessive disease leads to progressive neurodegeneration and sometimes to early death. Stem cell transplantation has been shown to be an effective treatment. In the five patients published so far, correction of skeletal abnormalities and improvement of neuropsychological capabilities have been observed. We report the first patient who received a T-cell-depleted peripheral blood stem cell transplantation (PBSCT) for alpha-mannosidosis. The diagnosis of alpha-mannosidosis was made at the age of 14 months. At the age of 24 months, he underwent PBSCT with T-cell depletion by CD34-positive selection from his HLA phenotypically identical mother. Conditioning was carried out with busulfan (20 mg/kg), cyclophosphamide (200 mg/kg), OKT3 and methylprednisolone. The patient is alive and well 27 months after PBSCT and has made significant developmental progress. The pattern of urinary oligosaccharides has returned to almost normal. CD34-positive-selected PBSCT is a feasible option to reduce risk for GVHD for these patients.

Anti-Inflammatory Agents↗
PubMed1998

[Risks and complications anesthesia with intubation during dental treatment].

In many hospitals and dental clinics the delivery of dental care under general anesthesia is a routine practice. Most often mentally handicapped patients and uncooperative children are concerned. In order to minimise the risk of anesthesia-related complications, an exact preoperative examination of anatomic particularities and accompanying diseases is mandatory. An analysis of 402 anesthesias performed from 1992 to 1995 revealed a 13.9% of complications. Main problems observed were difficult intubation and marked drop in blood pressure. Despite of a relatively low anesthetic risk we still limit ambulatory anesthesias to patients belonging to the ASA risk groups 1 and 2 with a maximum extent of the narcosis of 2 hours.

Ambulatory Care↗
PubMed1996

Endocrine disorders in septo-optic dysplasia (De Morsier syndrome)--evaluation and follow up of 18 patients.

UNLABELLED: Septo-optic dysplasia (SOD) is characterized by hypoplasia of the optic nerve, various types of forebrain defects and hormonal deficiencies. We have studied the clinical and endocrinological characteristics of 18 such patients retrospectively to: (1) better define the endocrine abnormalities in children with SOD; and (2) to find approaches for the interdisciplinary long-term care of children with SOD. The children were seen at the Children's Hospital of the University of Munich from 1976 to 1992 (8 boys, 10 girls; age at initial presentation: 1 day-13 years of age, mean 1.9 years). Unilateral hypoplasia of the optic nerve was found in 7 cases, bilateral hypoplasia in 11. Sonographic, CCT or MRI yielded the following results: 4 of the patients had a cavum septum pellucidum, 3 patients had hypoplasia of the cerebellum, 1 aplasia of the corpus callosum and 1 aplasia of the fornix. An empty sella with or without an ectopic pituitary was seen in 4 cases. Height standard deviation score (SDS) at time of diagnosis was -4.0 to +0.4, mean -2.92. Endocrine deficiencies were present in all 11 patients who had undergone endocrinological investigations. Seven patients suffered from isolated growth hormone (GH) deficiency or multiple hypopituitarism. One had diabetes insipidus centralis, 2 had hypogonadotropic hypogonadism, 1 had hypothyroidism and 2 adrenal insufficiency. Hypothalamic testing was performed only in a subset of patients: in 5 of 11 children tested a thyrotropin releasing hormone (TRH test), in two out of nine a gonadotropin releasing hormone (GnRH) test, and in three out of six GH releasing hormone (GHRH) test yielded abnormal results. High prolactin levels were measured in two out of five patients. CONCLUSION: SOD is characterized by optic nerve hypoplasia and a variety of endocrine deficiencies. In addition, forebrain malformations are present in most SOD patients. Hormonal disorders are present in some SOD patients which may be of hypothalamic origin and need to be investigated systematically.

Adolescent↗
PubMed1990

The influence of general, volatile anesthetics on the dynamic properties of model membranes.

The microscopic mechanism of general anesthesia is still not known but it may be located in the membrane region of nerve cells. In the present article microwave experiments on model membrane systems are discussed. At these particular frequencies a significant decrease of the systems' complex dielectric function is measured when it is exposed to volatile anesthetics. This effect is reversible as well as being identical for chemically quite different anesthetics. The corresponding anesthetic concentrations in the samples are relevant for medical anesthesia. The underlying microscopic mechanism is a decrease in the Debye relaxation frequency (and correspondingly an increase in viscosity) of those water molecules which are localized at the membranes' surfaces. General anesthesia might be a consequence of such a viscosity change at hydrophilic surfaces.

Absorption↗
PubMed1982

Skin surface PCO2 monitoring in newborn infants in shock: effect of hypotension and electrode temperature.

We studied the effect of hypotension and of electrode temperature (41 degrees C to 44 degrees C) on the relation of skin surface PCO2 (Roche prototype) to arterial PCO2 in 24 sick neonates of 690 to 3,500 gm with systolic blood pressures of 5 to 70 mm Hg. PsCO2 closely correlated with PaCO2. The standard error of estimating PaCO2 from PsCO2 was 3.02 torr at 44 degrees C, 3.20 torr at 43 degrees C, and 3.57 torr at 41 degrees C. The pH (6.89 to 7.61), body temperature (33.5 to 38.1 degrees C), hematocrit (0.28 to 0.65), scleredema, or treatment with tolazoline did not affect the relation of PsCO2 to PaCO2. PsCO2 grossly exceeded the predicted value at systolic blood pressures below 15 mm Hg, irrespective of electrode temperature.

Blood↗