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.

[Effects of mechanical strain on human osteoblastic precursor cells in type I collagen matrices]. / Effekte mechanischer Reize auf humane osteoblastäre Zellen in einer dreidimensionalen Kollagen-Typ-I-Matrix.

BACKGROUND: The aim of the present study was to investigate the effect of mechanical strain on human osteoblastic precursor cells in a three-dimensional scaffold. METHODS: Osteoblastic precursor cells were seeded in a collagen type I gel and mechanically stretched by daily application of cyclic uniaxial strain. The expression of histone H4, core binding factor 1, alkaline phosphatase, osteopontin, osteocalcin, and collagen type I was investigated by analysing the mRNA. Cell and matrix orientation were investigated by scanning electron microscopy. RESULTS: Cyclic stretching increased cell proliferation. The expression of osteogenic markers was slightly increased by mechanical strain. The cells and matrix were strictly oriented in the stress direction. CONCLUSION: The application of mechanical load might have a beneficial effect on the quality and quantity of generated bone tissue and might be a important factor in tissue engineering of bone.

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.

Identification of glycoprotein gpTRL10 as a structural component of human cytomegalovirus.

Human cytomegalovirus (HCMV) has a coding capacity for glycoproteins which far exceeds that of other herpesviruses. Few of these proteins have been characterized. We have investigated the gene product(s) of reading frame 10, which is present in both the internal and terminal repeat regions of HCMV strain AD169 and only once in clinical isolates. The putative protein product is a 171-amino-acid glycoprotein with a theoretical mass of 20.5 kDa. We characterized the protein encoded by this reading frame in the laboratory strain AD169 and a recent isolate, TB40E. The results from both strains were comparable. Northern blot analyses showed that the gene was transcribed with early/late kinetics. Two proteins of 22 and 23.5-kDa were detected in virus-infected cells and in cells transiently expressing recombinant TRL10. Both forms contained only high-mannose-linked carbohydrate modifications. In addition, virus-infected cells expressed small amounts of the protein modified with complex N-linked sugars. Image analysis localized transiently expressed TRL10 to the endoplasmic reticulum. Immunoblot analyses as well as immunoelectron microscopy of purified virions demonstrated that TRL10 represents a structural component of the virus particle. Immunoblot analysis in the absence of reducing agents indicated that TRL10, like the other HCMV envelope glycoproteins, is present in a disulfide-linked complex. Sequence analysis of the TRL10 coding region in nine low-passage clinical isolates revealed strain-specific variation. In summary, the protein product of the TRL10 open reading frame represents a novel structural glycoprotein of HCMV and was termed gpTRL10.

[Is appendectomy really performed too frequently? Results of the prospective multicenter study of the Swiss Society of General Surgery]. / Wird tatsächlich zu häufig appendektomiert? Resultate der prospektiven Multicenterstudie der Schweizerischen Gesellschaft für Allgemeinchirurgie (SGAC).

Scientific publications and provoking criticism from the lay press have recently pointed out, that appendices may be surgically removed too frequent and without indisputable necessity. In an attempt to verify these questionable statements, the Swiss Society for General Surgery (SGAC) initiated a prospective controlled multi center trial. From September 1997 to December 1998, hundred and twenty-five institutions documented 4603 appendectomies performed due to a suspected appendicitis. Histological investigation of all specimens revealed a 7% rate of normal appendices, 7.2% for patients with national health service (NHS) and 5.9% for patients with private insurances respectively. Compared to the results of the literature, where a frequency of normal appendices around 15% is judged as standard, these results are excellent. In 17.2% of the patients (15.9% NHS and 23.6% privately insured patients) an "appendicitis perforata" was observed. This percentage remains in the range reported by other authors. The analysis of time of admission (i.e. day or night) and the delay from admission to surgery shows a distribution independent to the insurance of the patients. Therefore, the planned appendectomy for patients with private insurances does not exist. A different choice of the surgical technique could be observed depending on the insurance status. In 30.4% of the private insured patients a laparoscopic appendectomy was performed as compared to 22.6% of patients with NHS. Surprisingly, an identical median hospitalization time can be observed for both groups (laparoscopic 5.5 days, open surgery 5.5 days).

Catechol-O-methyltransferase inhibition attenuates levodopa toxicity in mesencephalic dopamine neurons.

Inhibition of catechol-O-methyltransferase (COMT; EC 2.1.1.6) is a new therapeutic strategy in the treatment of Parkinson's disease. However, nothing is known about the effects of COMT inhibition on levodopa (L-dopa)-induced toxicity in dopamine (DA) neurons. Therefore we evaluated the effects of the selective COMT inhibitors Ro 41-0960, OR-486, and tolcapone alone and in combination with L-dopa in primary mesencephalic cultures from rat. Neither COMT inhibitor affected the growth of tyrosine hydroxylase immunoreactive (THir) cells with concentrations up to 10 microM when studied alone. However, Ro 41-0960 reduced the L-dopa-induced THir cell loss after 24 h in a dose-dependent manner, shifting the TD(50) value from 21 microM in the absence to 71 microM in the presence of 1 microM Ro 41-0960 (P <.01) without affecting survival of non-DA neurons. OR-486 and the clinically used COMT inhibitor tolcapone showed similar effects. In contrast, toxicity induced by D-dopa was not altered by COMT inhibitors. Furthermore, the primary metabolite of L-dopa formed by COMT, 3-O-methyldopa, and the methyl group donor S-adenosyl-L-methionine used by COMT did not alter THir neuron survival and L-dopa-induced toxicity, respectively, with concentrations up to 100 microM. These data demonstrate that COMT inhibition attenuates L-dopa toxicity toward DA neurons in vitro, but probably not by preventing 3-O-methyldopa production or cellular S-adenosyl-L-methionine depletion.

[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.

[Leiomyosarcoma of the small intestine]. / Leiomyosarkom des Dünndarms.

Leiomyosarcomas of the small bowel are quite rare. These tumors are mostly located in the jejunum distal of the duodeno-jejunal flexure. The non-metastasizing leiomyosarcomas have a good prognosis, according to the literature. The adequate surgical treatment is the resection of the small bowel. Chemotherapy is discussed if there is evidence of metastatic disease. For the diagnosis of leiomyosarcomas tumor markers have no significance. We report the case of a 79 years old patient with a leiomyosarcoma of the jejunum who was admitted as an emergency with an acute abdomen and underlying chronic anaemia. This case demonstrates the often unspecific symptoms and characteristics of leiomyosarcomas.

[The LAPARO-HOOK for use in gas-free laparoscopy]. / Der LAPARO-HOOK für den Einsatz bei gaslosen laparoskopischen Operationen.

This report describes our newly developed retractor, the LAPARO-HOOK, for gasless laparoscopy. Compared to other systems it is less traumatic and easy to handle. The abdominal working space is similar to the one using a pneumoperitoneum. A further advantage, especially in the learning-phase, is the possibility to convert to traditional laparoscopy by insufflating CO2 at any time.

[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.

[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.