Self-assembled nanoparticle micro-shells templated by liquid crystal sorting.

A current goal in nanotechnology focuses on the assembly of different nanoparticle types into 3D organized structures. In this paper we report the use of a liquid crystal host phase in a new process for the generation of micron-scale vesicle-like nanoparticle shells stabilized by ligand-ligand interactions. The constructs formed consist of a robust, thin spherical layer, composed of closely packed quantum dots (QDs) and stabilized by local crystallization of the mesogenic ligands. Ligand structure can be tuned to vary QD packing within the shell and made UV cross-linkable to allow for intact shell extraction into toluene. The assembly method we describe could be extended to other nanoparticle types (metallic, magnetic etc.), where hollow shell formation is controlled by thermally sorting mesogen-functionalized nanoparticles in a liquid crystalline host material at the isotropic to nematic transition. This process represents a versatile method for making non-planar 3D nano-assemblies.

Tuning quantum-dot organization in liquid crystals for robust photonic applications.

Mesogenic ligands have the potential to provide control over the dispersion and stabilization of nanoparticles in liquid crystal (LC) phases. The creation of such hybrid materials is an important goal for the creation of soft tunable photonic devices, such as the LC laser. Herein, we present a comparison of isotropic and mesogenic ligands attached to the surface of CdSe (core-only) and CdSe/ZnS (core/shell) quantum dots (QDs). The mesogenic ligand's flexible arm structure enhances ligand alignment, with the local LC director promoting QD dispersion in the isotropic and nematic phases. To characterize QD dispersion on different length scales, we apply fluorescence microscopy, X-ray scattering, and scanning confocal photoluminescent imaging. These combined techniques demonstrate that the LC-modified QDs do not aggregate into the dense clusters observed for dots with simple isotropic ligands when dispersed in liquid crystal, but loosely associate in a fluid-like droplet with an average interparticle spacing >10 nm. Embedding the QDs in a cholesteric cavity, we observe comparable coupling effects to those reported for more closely packed isotropic ligands.

Evaluation of plasma trace element and mineral status in children and adolescents with phenylketonuria using data from inductively-coupled-plasma atomic emission and mass spectrometric analysis.

BACKGROUND: Phenylketonuria (PKU) is caused by a severe phenylalanine hydroxylase deficiency; the mainstay of treatment is a low-phenylalanine diet. A diet which is so restrictive is associated with a risk of nutritional deficiencies. We investigated plasma concentrations for 46 elements, including minerals and trace elements. METHODS: We enrolled 20 children and adolescents with PKU and 20 matched controls. Multi-elementary quantification was carried out by solution-based inductively coupled plasma atomic emission spectroscopy (ICP-AES) and ICP mass spectrometry (ICP-MS). RESULTS: With the exception of manganese and aluminium, no significant differences were found for element levels between PKU patients and controls. As a trend, manganese levels were lower in PKU patients than in control subjects (p < 0.05) but were within the reference range. There was a positive linear relationship between manganese and tyrosine levels in subjects with PKU (r(2) = 0.2295, p < 0.05). If detectable, potentially toxic elements were only identified in ultra-trace quantities in plasma samples of either group; aluminium levels were found to be slightly higher in PKU subjects than in controls (p < 0.01). CONCLUSION: The combination of ICP-AES and ICP-MS data is a useful diagnostic tool for element quantification at a high analytical rate and for monitoring bio-element status, e.g. in patients on a restrictive diet.

Hereditary hyperferritinemia cataract syndrome: clinical, genetic, and laboratory findings in 5 families.

BACKGROUND: The hereditary hyperferritinemia cataract syndrome (HHCS) is an autosomal dominant disorder characterized by high serum ferritin and early onset cataract. Mutations in the iron responsive element (IRE) within the 5' untranslated region of the L-ferritin (FTL) gene lead to constitutive L-ferritin synthesis resulting in hyperferritinemia. Bilateral cataract formation is caused by the intracellular accumulation of ferritin in the lens. PATIENTS: 4 children from unrelated families were referred for further exploration of hyperferritinemia which was detected during the diagnostic work-up of gastroenterological or hematological disorders. 1 patient was primarily referred for the investigation of bilateral cataract.Diagnostics included routine blood analysis, including complete blood count, iron status, liver and kidney parameters, a physical and an ophthalmological examination. Molecular genetic analysis of the FTL IRE was performed in 4 patients by PCR from genomic DNA and subsequent direct sequencing. RESULTS: All index patients presented with isolated hyperferritinemia without iron overload and had a positive family history for early onset cataract. Age at onset and disease severity varied between different families and among family members. Molecular genetic analysis revealed point mutations within the FTL IRE. CONCLUSION: In patients with hyperferritinemia but without any other sign of iron overload or inflammation HHCS should be considered to avoid complex and invasive procedures. Vice versa, in patients with familial inherited cataract the early serum ferritin measurement helps to avoid unnecessary diagnostics.

Microarray analysis of placental tissue in intrauterine growth restriction.

OBJECTIVE: Besides foetal or maternal disorders, placental dysfunction is a major cause of intrauterine growth restriction (IUGR). Although numerous macro- and histopathological changes have been described, little is known about the precise aetiology and the contribution of foetal/placental genes in this disorder. DESIGN: Placental tissues of 20 IUGR and control neonates were analysed by microarray technique. Four of the regulated genes with possible relevance in the pathogenesis of IUGR and its consequences were further studied in placentas of 27 IUGR and 35 control newborns. RESULTS: Elevated gene expression of leptin, corticotrophin-releasing hormone (CRH), and IGF-binding protein-1 (IGFBP-1) in IUGR placentas could be confirmed in the larger group by real-time PCR, whereas prolactin showed no significant difference. Accordingly, protein expression of leptin and IGFBP-1 depicted by Western blot was elevated in IUGR, prolactin was not different. Birthweight standard deviation score (SDS) correlated negatively to leptin, IGFBP-1, and CRH, whereas placental weight correlated only to IGFBP-1. Leptin correlated negatively to gestational age of IUGR patients and positively to placental score, a marker of severity of impaired foeto-placental circulation. CONCLUSIONS: As confirmed in a large group of IUGR and control samples, the up-regulated factors leptin, IGFBP-1, and CRH may serve as candidate genes for the prediction of subsequent metabolic consequences in IUGR newborns. These three factors may not only influence growth of the foetus, but might also interact with programming of its metabolic functions, which has to be determined in an ongoing study.

Tissue engineering of bone: effects of mechanical strain on osteoblastic cells in type I collagen matrices.

The aim of the present study was to investigate the effect of cyclic uniaxial mechanical strain on a human osteoblastic precursor cell line (hFOB 1.19) in three-dimensional type I collagen matrices. Cell seeded collagen constructs were mechanically stretched by a daily application of cyclic uniaxial strain using a special motor-driven apparatus and compared to unstretched controls. Expression of genes involved in cell proliferation and osteoblastic differentiation as well as matrix production were investigated by analyzing the mRNA of histone H4, core binding factor 1, alkaline phosphatase, osteopontin, osteocalcin, and collagen type I (Col I) up to a cultivation period of 3 weeks using real-time PCR. Cyclic stretching of cell seeded Col I matrices at a magnitude occurring in healing bone increased cell proliferation and slightly elevated the expression of nearly all investigated genes over unstrained controls at various time points. It was concluded that mechanical load promotes the proliferation and differentiation of osteoblastic precursor cells in a Col I matrix and that the application of mechanical stimuli may have a beneficial effect on in vitro tissue formation.

Modulation of DNA repair processes by arsenic and selenium compounds.

Nickel, cadmium, cobalt and arsenic compounds are well known carcinogens to humans and experimental animals. In addition to the induction of mainly oxidative DNA damage, they interfere with nucleotide and base excision repair (BER) at low, non-cytotoxic concentrations. In case of arsenic, an inactivation of DNA repair has also been observed for the trivalent and pentavalent methylated metabolites, with the strongest effects exerted by MMA(III) and DMA(III). As potential molecular targets, interactions with so-called zinc finger proteins involved in DNA repair and/or DNA damage signaling have been identified. For example, arsenite suppresses poly(ADP-ribosyl)ation at extremely low, environmentally relevant concentrations. Also, Fpg and XPA involved in BER and NER, respectively, are inactivated by arsenite, MMA(III) and DMA(III). Nevertheless, an interaction with the zinc finger structures of DNA repair proteins may also occur by essential trace elements such as certain selenium compounds, which appear to exert anticarcinogenic properties at low concentrations but may compromise genetic stability at higher concentrations.

Interference by toxic metal ions with zinc-dependent proteins involved in maintaining genomic stability.

Metal ions are essential components of biological systems; nevertheless, even essential elements may have toxic or carcinogenic properties. Thus, besides As(III) and Cd(II), also Ni(II) and Co(II) have been shown previously to disturb different types of DNA repair systems at low, non-cytotoxic concentrations. Since some metals exert high affinities for SH groups, we investigated whether zinc finger structures in DNA-binding motifs of DNA repair proteins are potential targets for toxic metal ions. The bacterial formamidopyrimidine-DNA glycosylase (Fpg protein) involved in base excision repair was inhibited by Cd(II), Cu(II) and Hg(II) with increasing efficiencies, whereas Co(II), As(III), Pb(II) and Ni(II) had no effect. Furthermore, Cd(II) still disturbed enzyme function when bound to metallothionein. Strong inhibition was also observed in the presence of phenylselenyl chloride, followed by selenocystine, while selenomethionine was not inhibitory. Regarding the mammalian XPA protein involved in the recognition of DNA lesions during nucleotide excision repair, its DNA-binding capacity was diminished by Cd(II), Cu(II), Ni(II) and Co(II), while Hg(II), Pb(II) and As(III) were ineffective. Finally, the H(2)O(2)-induced activation of the poly(ADP-ribose)polymerase (PARP) involved in DNA strand break detection and apoptosis was greatly reduced by Cd(II), Co(II), Ni(II) and As(III). Similarly, the disruption of correct p53 folding and DNA binding by Cd(II), Ni(II) and Co(II) has been shown by other authors. Therefore, zinc-dependent proteins involved in DNA repair and cell-cycle control may represent sensitive targets for some toxic metals such as Cd(II), Ni(II), Co(II) and Cu(II), as well as for some selenium compounds. Relevant mechanisms of inhibition appear to be the displacement of zinc by other transition metals as well as redox reactions leading to thiol/disulfide interchange.

[The value of Adams and de Weese's technic of cava clipping]. / Der Stellenwert des Cava-Clippings nach Adams und de Weese.

Indications and methods of inferior vena cava interruption in the management of recurrent pulmonary embolism are discussed. The results of a collected series are analyzed with special regard to the partial interruption technique using the Adams and de Weese clip. Five of our own cases, followed up 1 year postoperatively, are presented.

[Squamous epithelial carcinoma in a sigmoid diverticulum. Case report and review of the literature]. / Plattenepithelcarcinom in einem Sigmadivertikel. Fallbericht und Literaturübersicht.

A case of primary squamous cell carcinoma arising in a sigmoid diverticulum is reported. The literature concerning pure squamous cell carcinoma of the colon is reviewed. With regard of possible pathogenesis of squamous cell carcinoma of the colon 76 diverticula are examined and the results discussed.

[Laparoscopic endoscopic pre-peritoneal combined hernia operation in incarcerated indirect inguinal hernia]. / Laparoskopisch endoskopisch-präperitoneale kombinierte Hernien-Operation bei incarcerierter indirekter Inguinalhernie.

We report on a 73-year-old patient with an incarcerated right sided groin hernia. First the incarcerated small bowel was gently retracted laparoscopically; then using the extraperitoneal endoscopic approach the hernial sack was redused and a 15/13 cm prosthesis (polypropylene mesh) brought in appropriate position and fixed with endo-staples. Prior to closing the trocar-incisions the vitality of the small bowel was checked once again laparoscopically.

[Complications following colon surgery]. / Komplikationen nach Operationen am Dickdarm

615 transperitoneal operations on the colon and rectum produced the following results. 377 abdominoperineal resections, anterior resections, partial and subtotal colectomies and proctocolectomies, 87 closures of colostomies and 151 operations with resection. 66% of the operations were required due to tumors. The death rate with 545 preopreratively prepared and scheduled operations was 8.1% whereas with the 70 emergency operations it was 25.7%. In 254 or 41.3% of the cases there were postoperative complications. Severe postoperative complications due to infection were the most frequent, followed by cardiopulmonary, haemorrhagic, urological and complications due to ileus. The quotient of insufficiency with the 356 anastomoses was 16%, the death rate 1.4%.

[Anorectal pressure measurement with a microtransducer]. / Anorektale Druckmessung mit Mikrotransducer.

In 20 healthy subjects anorectal pressure has been measured with a micro-tip pressure transducer. This method is shown to be superior to conventional measurements with perfusion or balloon catheters. The main features of the micro-tip pressure transducer are internal calibration, thermal stability and linearity in pressure transmission. Our results show significantly higher pressure profiles at rest and during squeezing in young males than in young females. Exact and selective pressure data can be obtained from any area of the anal canal in supine as well as in standing position. Therefore we recommend this method for evaluation and follow-up of all the cases with sphincteric incompetence.

[Surgical therapy of anal fissure]. / Chirurgische Therapie der Analfissur.

Lateral internal sphincterotomy has shown to be a very efficient method to treat acute and especially chronic anal fissure. The question remains, whether it is possible to optimate the short and long term outcome by individualizing the extent of sphincterotomy. This can be done by calculating the length of the anal canal and the area under the curve on a preoperative manometric pressure profile. We present the short and long term results over 3 years in a consecutive series of 30 anal fissures. All patients remained symptomfree and had full anal sphincter competence.

[Late results after individualized lateral internal sphincterotomy]. / Spätresultate nach individualisierter lateraler interner Sphinkterotomie.

A total of 75 patients underwent individualized lateral internal sphincterotomy for acute and chronic anal fissure (n = 30) or high pressure hemorrhoids (n = 45) and were followed-up 3 months and 3 years (13-66 months) postoperatively. All but one patient with anal fissure (97%) and 38 out of 45 patients with hemorrhoids (84%) remained symptom free; only one patient (1.3%) occasionally had symptoms of minor incontinence. Following the operation both the maximum resting pressure and the medium anal pressure fell significantly and were completely or nearly normalized in 54 (72%) and 17 (23%) patients respectively. At medium follow-up of 3 months and 3 years postoperatively there was no significant difference in the two sets of postoperative manometric results.

[Deep venous thrombosis of the lower limb: experiences of thrombectomy within and outside the iliacofemoral segment]. / Tiefe Venenthrombose der unteren Extremitäten: Erfahrungen mit der Thrombektomie inner- und ausserhalb des iliakofemoralen Bereichs.

A series of 23 venous thrombectomies of the lower limb is presented. In 19 instances indirect thrombectomy of the iliacofemoral segment was performed. 1 direct thrombectomy of the v. cava inferior led to full lumen restoration. Direct thrombectomy of the popliteal vein was attempted in 3 cases, resulting in phlebographic and clinical normalization in 2 instances. In no instance did pulmonary embolism occur during or after venous thrombectomy.

[Endoscopic pre-peritoneal prolene mesh-plasty for management of inguinal and femoral hernias]. / Die endoskopische präperitoneale Prolennetzplastik zur Versorgung von Inguinal- und Femoralhernien.

From October 1994 to March 1996 158 inguinal or femoral hernias were repaired in 124 patients through a total extraperitoneal approach. The repairs were done with polypropylene mesh. The patients were seen 6 to 8 weeks postop; until today 57 patients were seen 12 months postop. This method favours an early return to work. Patients with unilateral hernias returned to work after an average of 14 days, patients with bilateral hernias after an average of 19 days. Complications were rare and mostly minor. So far we have seen no recurrences and no mesh related complications. We consider the laparoscopic extraperitoneal mesh repair a safe procedure for inguinal and femoral hernias.

[Chronic pancreatitis of the head of the pancreas in hyperplasia of the body and tail of the pancreas]. / Chronische Pankreaskopf-Pankreatitis bei Hypoplasie von Pankreaskorpus und -schwanz.

We report a case of chronic pancreatitis of the head of the pancreas complicated with insulin-requiring diabetes mellitus, in a 44-year-old woman with hypoplasia of the dorsal pancreas. Preoperative ultrasonography, computerized tomography and angiography revealed a calcifying retroperitoneal mass, which on explorative laparotomy proved to be a severe chronic pancreatitis of the head of the pancreas with a finding of abnormal visibility of the confluens venosum and absence of both the corpus and the tail of the pancreas. The postoperative course following pylorus-preserving duodenopancreatectomy was uneventful.