The biocompatibility of dense and porous Nickel-Titanium produced by selective laser melting

Nickel-Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required.

Living at high altitude and risk of hospitalisation for atopic asthma in children: results from a large prospective birth-cohort study

BACKGROUND

Asthma is among the most common chronic diseases in childhood and is steadily increasing in prevalence. Better characterisation of factors that determine the risk of hospitalisation for atopic asthma in childhood may help design prevention programmes and improve our understanding of disease pathobiology. This study will focus on the altitude of residence.

METHODS

This is an ongoing prospective birth-cohort study that enrolled all live-born infants in the Tyrol. Between 1994 and 1999, baseline data were collected for 33 808 infants. From 2000 to 2005, all children hospitalised for atopic asthma at the age of > or =6 years (n = 305) were identified by a careful search of hospital databases. Disease status was ascertained from the typical medical history, a thorough examination and proof of atopy.

RESULTS

Living at higher altitude was associated with an enhanced risk of hospitalisation for atopic asthma (multivariate RRs (95% confidence interval 2.08 (1.45 to 2.98) and 1.49 (1.05 to 2.11) for a comparison between altitude categories > or =1200 m and 900-1199 m versus <900 m; p<0.001). This finding applied equally to hospital admissions in spring, summer, autumn and winter. When altitude of residence was analysed as a continuous variable, the risk for asthma hospitalisation increased by 7% for each 100-m increase in altitude (p = 0.013).

CONCLUSIONS

This large prospective study shows a significant association between the risk of hospitalisation for atopic asthma and altitude of residence between 450 and 1800 m. The underlying mechanisms remain to be elucidated, but it is tempting to speculate about a role for altitude characteristics such as the decline in outdoor temperature and air humidity and increase in ozone levels, which may trigger airway hyper-responsiveness and attenuate lung function.

Subduction and collision processes in the Central Andes constrained by converted seismic phases

The Central Andes are the Earth's highest mountain belt formed by ocean-continent collision. Most of this uplift is thought to have occurred in the past 20 Myr, owing mainly to thickening of the continental crust, dominated by tectonic shortening. Here we use P-to-S (compressional-to-shear) converted teleseismic waves observed on several temporary networks in the Central Andes to image the deep structure associated with these tectonic processes. We find that the Moho (the Mohorovicić discontinuity--generally thought to separate crust from mantle) ranges from a depth of 75 km under the Altiplano plateau to 50 km beneath the 4-km-high Puna plateau. This relatively thin crust below such a high-elevation region indicates that thinning of the lithospheric mantle may have contributed to the uplift of the Puna plateau. We have also imaged the subducted crust of the Nazca oceanic plate down to 120 km depth, where it becomes invisible to converted teleseismic waves, probably owing to completion of the gabbro-eclogite transformation; this is direct evidence for the presence of kinetically delayed metamorphic reactions in subducting plates. Most of the intermediate-depth seismicity in the subducting plate stops at 120 km depth as well, suggesting a relation with this transformation. We see an intracrustal low-velocity zone, 10-20 km thick, below the entire Altiplano and Puna plateaux, which we interpret as a zone of continuing metamorphism and partial melting that decouples upper-crustal imbrication from lower-crustal thickening.

Regulation of ion channels in rat hepatocytes

Patch-clamp studies have been performed to elucidate single ion channels in rat hepatocytes. In rat hepatocytes two types of ion channel have been identified: an inwardly rectifying K+ channel with a mean inward conductance of 55 +/- 6.5 pS (n = 20) and a mean outward conductance of 25 +/- 3.2 pS (n = 20) in the inside-out configuration with 145 mmol/l KCl on either side of the patch as well as an outwardly rectifying Cl- channel with a mean outward conductance of 30 +/- 4.5 pS (n = 8) and a mean inward conductance of 10 +/- 2.3 pS (n = 6) in the inside-out configuration with symmetrical 145 mmol/l KCl. The open probability of these channels is virtually insensitive to Ca2+ activity on the intracellular side. Accordingly, the Ca2+ ionophore ionomycin had no effect on cell membrane potential. Dibutyryl-cAMP (db-cAMP) hyperpolarizes the cell membrane and increases the activity of the 55-pS inwardly rectifying K+ channel by reducing the duration of closure between bursts. Forskolin similarly hyperpolarizes the cell membrane. The inwardly rectifying K+ channel is inhibited by progesterone, while the outwardly rectifying Cl- channel is insensitive to progesterone.

[AgNOR analysis of astrocytoma in childhood]

To evaluate the malignant potential of a tumor, data about its proliferative rate are essential. In this study clinical data, histological grading and immunohistochemical marker PCNA were applied on astrocytomas in childhood and were correlated to number, size and distribution of AgNORs. Tumor material from 90 patients, aged 1 to 15 years, was available. Histological grading, immunohistochemistry and AgNOR staining were performed on paraffin sections. PCNA-positivity was evaluated semiquantitatively. The AgNORs were quantified on 100 nuclei/case with an image analysis system. With aggravating malignancy we could show a shorter anamnesis, a lower survival and a higher PCNA-reactivity. We found a strong correlation between several AgNOR-features and the grade of malignancy of the astrocytomas, especially for the number of the AgNORs (from grade I: 1.73 AgNORs/nucleus to grade IV: 4.56 AgNORs/nucleus), the size of the AgNORs and its area amount of the nucleus. There were correlations between AgNOR-number and PCNA-reactivity as well as AgNOR-number and survival. Analysis of AgNORs, consequently, should provide prognostically relevant information helpful in more effective grading of astrocytomas.

Effects of H2O2 on membrane potential and [Ca2+]i of cultured rat arterial smooth muscle cells

The effect of 1 mmol/l H2O2 was studied on the membrane potential and [Ca2+]i with microelectrodes and the fura-2 technique, respectively. H2O2 induced a biphasic increase in [Ca2+]i with a fast transient peak and a subsequent plateau. H2O2 also led to a biphasic hyperpolarization of the cells with a similar time course. This was followed by a slight depolarization after wash-out of H2O2. External Ca2+ free solutions and treatment with the Ca2+ ionophore A23187 (1 mumol/l) abolished the effect of H2O2 on [Ca2+]i and almost entirely reduced the effect on the membrane potential. Phenylephrine (10 mumol/l) or A23187 also induced very similar biphasic hyperpolarizations of the membrane as H2O2 which were fully reversible after wash-out. It is concluded that H2O2 hyperpolarizes the membrane by opening of Ca2+ dependent K+ channels.

Novel Galloylhamameloses from Hamamelis virginiana1

The range of natural galloylhamameloses is extended by the recognition of the highly unstable novel analogues, the 1- O-(4-hydroxybenzoyl)-2',5-di- O-galloyl-alpha- D-hamamelofuranose and its 1- O-beta-anomer. The observed facile elimination of the C-1 acyl moiety is discussed and a mechanism proposed. These compounds are accompanied in the bark of HAMAMELIS VIRGINIANA by the "conventional" hamamelitannin, the related new 1,2',5-tri- O-galloyl-alpha- D-hamamelofuranose, and a tentatively characterized di- O-galloyl- D-hamamelopyranose, the first pyranose analogue, shown to be also present in commercially available hamamelitannin. The structures of these compounds were established from spectroscopic evidence of their acetate derivatives.

Fulminant leukemic polyradiculoneuropathy in a case of B-cell prolymphocytic leukemia. A clinicopathologic report

A 52 year old man with a 10-month history of B-cell prolymphocytic leukemia (PLL) died of an apparent acute fulminant polyradiculoneuropathy, a condition generally attributed to paraneoplastic complication. The pathologic examination disclosed diffuse leukemic infiltrations of the peripheral nervous system. It is suggested that this particularly aggressive form of B-cell chronic prolymphocytic leukemia presented a constellation of features that promoted the invasion of the peripheral nervous system by way of the bloodstream and may explain the unusual clinical presentation.

Basilar artery occlusion in an adolescent girl: a risk of oral contraceptives?

An 18-year-old adolescent girl died of an extensive pontine infarction. At postmortem examination she was found to have a thrombosis of the basilar and intracranial vertebral arteries with associated focal hyperplasia of the intima. Her ovaries were grossly small and inactive, with absent corpora lutea. Based on these findings, we suspect she was taking oral contraceptives. In cases of unexplained fatal strokes in young females, careful pathologic examination of the ovaries may provide etiological clues.

Long survival of primary cerebral lymphoma with progressive radiation necrosis

A 56-year-old man lived 8 years after excision and irradiation of a primary cerebral lymphoma. Delayed radiation necrosis caused progressive neurologic deterioration and probably his steroid-responsive episodes of obtundation. Vasogenic edema induced by radiation may account for the latter. An incidental extraneural lymphoma was found postmortem without evidence of CNS lymphoma.

Development of a screening program for tardive dyskinesia: feasibility issues

This report is part of a feasibility study focused upon developing a valid and reliable method of screening for tardive dyskinesia. The research questions concerned establishing the validity and reliability of the procedure, the acceptability of the procedure to the subjects, and the characteristics of the subjects with scores that exceeded more than a minimal level. Sixty patients were screened in four randomly selected psychiatric aftercare homes. A 12-hour training program was developed to prepare the raters. The interrater reliability achieved for total score using the Abnormal Involuntary Movement Scale (AIMS) was .90, p less than .01, and the validity of the examination was achieved and maintained at an 80-percent agreement level between the nurse raters and a study expert. Thirty percent of the population had scores exceeding minimal symptoms for tardive dyskinesia. The screening program was acceptable to the subjects. A program of training for professional-level raters is described, which is applicable to many settings.

An unusual malformation of the forebrain and concomitant destructive encephalopathy with calcifications

A 9-year old boy with profound mental retardation and severe neurologic deficit presented an unusual malformation of the forebrain distinguished by the following features: 1) microtelencephalon, alobulation, afissuration, and abnormal convolutional pattern; 2) persistence of hippocampal formation at its embryonic site in the dorsomedial wall of the telencephalon; 3) hypoplasia and abnormal configuration of ventricles; 4) agenesis of cerebral commissures; and 5) abnormal location and orientation of gray structures. Important concomitant findings characterized by severe destructive lesions, massive calcification, granular ependymitis, and low grade inflammation were suggestive of late sequelae of an infectious process, possibly congenital. Transplacental transmission of an unidentified pathogen with teratogenic properties was hypothesized as the probable cause. The teratogenic insult started in an early embryonic period and affected primarily the development of the neopallium in the telencephalic wall. The arrested development of the neopallium disrupted the chain of interdependent developmental events; consequently characteristic morphological modifications normally induced by the continuous growth and differentiation of the neopallium failed to occur or took an abnormal course. The name architelencephalon (Greek: arche, beginning; telencephalon, cerebral hemispheres) proposed for this particular malformation of the forebrain indicates its resemblance both to the human brain at early stages of development and also to mammalian brains on a lower level of phylogeny. Associated anomalies included an unilateral microphthalmia with cataract, severe stenosis of the aqueduct of Sylvius and macrocephaly. The microphthalmia was either a developmental anomaly or was infectious in origin. The stenosis of the aqueduct was attributed to granular ependymitis. Tearing of the thin dorsal diencephalic plate and arachnoid membrane and escape of the cerebrospinal fluid into the subdural space probably accounted for the macrocephaly.