Capacitive microphone with a surface micromachined backplate usingelectroplating technology

A technology for surface micromachining of free-standing metal microstructures using metal electrodeposition on a sacrificial photoresist layer has been applied to a condenser microphone. Electroplating technology has been used to implement a suspended and perforated 15-μm-thick microstructure in copper, which serves as backplate electrode in the condenser microphone. The 1.8×1.8 mm ² large microphone diaphragm is in monocrystalline silicon and is fabricated with anisotropic etching of the substrate wafer. The realized prototypes have a measured sensitivity of 1.4 mV/Pa using a bias voltage of 28 V. The bandwidth is limited by an anti-resonance at 14 kHz which is due to the semi-rigid backplate. The resonance behavior of the backplate structure has been analyzed with finite element modeling with results in good agreement with measured data     

Composite polytetrafluroethylene/vein bypass grafts: conventional distal vein segment or vein cuff?

Faecal samples from asymptomatic dairy cows and calves from a farm on the Island Falster, Denmark, were examined by a sucrose gradient flotation technique. Giardia cysts were found in 7.6% of the 92 samples, and estimated cyst excretion rates ranged from 50-200 cysts per gram faeces. Given that Giardia has the potential to cause clinical disease in cattle and to be transmitted to other animal species and humans, finding the parasite in cattle may be of major epidemiological significance. Future work should focus on elucidating the pathogenicity, transmission patterns and the genetic structure of Giardia populations in cattle in Denmark.     

Antithrombotic effect of recombinant truncated tissue factor pathway inhibitor (TFPI1-161) in experimental venous thrombosis--a comparison with low molecular weight heparin

The aim was to investigate whether a truncated recombinant Tissue Factor Pathway Inhibitor (TFPI1-161), which lacked the third Kunitz-type domain and the basic c-terminal region, had an antithrombotic effect comparable to LMWH in a randomised double-dummy study. The experimental thrombosis was induced in jugular veins, in a total of 40 rabbits by a combination of destruction of the endothelium and restricted blood flow. Group 1: placebo, gr 2: LMWH 60 anti-FXa IU/kg, gr 3-5: 0.1, 1.0 and 10.0 mg/kg TFPI1-161. TFPI1-161 reduced the thrombus weights in all treated groups, significantly in doses of 1.0 and 10.0 mg/kg compared to placebo. The frequency of thrombosis and occlusive thrombosis were also significantly reduced in those doses. The antithrombotic properties of TFPI1-161 (1.0-10.0 mg/kg) measured as thrombus weight, frequency of thrombosis and frequency of occlusive thrombosis was equivalent to the anti-thrombotic properties of LMWH. In the anti-FXa, APTT and PT-assays TFPI1-161 displayed a dose dependent increase of activity. Recombinant-TFPI1-161 did not influence the anti-FIIa-assay. No haemorrhagic side effects were noted.     

Passive air sampling using semipermeable membrane devices at different wind-speeds in situ calibrated by performance reference compounds

Semipermeable membrane devices (SPMDs) are passive samplers used to measure the vapor phase of organic pollutants in air. This study tested whether extremely high wind-speeds during a 21-day sampling increased the sampling rates of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), and whether the release of performance reference compounds (PRCs) was related to the uptakes at different wind-speeds. Five samplers were deployed in an indoor, unheated, and dark wind tunnel with different wind-speeds at each site (6-50 m s(-1)). In addition, one sampler was deployed outside the wind tunnel and one outside the building. To test whether a sampler, designed to reduce the wind-speeds, decreased the uptake and release rates, each sampler in the wind tunnel included two SPMDs positioned inside a protective device and one unprotected SPMD outside the device. The highest amounts of PAHs and PCBs were found in the SPMDs exposed to the assumed highest wind-speeds. Thus, the SPMD sampling rates increased with increasing wind-speeds, indicating that the uptake was largely controlled by the boundary layer at the membrane-air interface. The coefficient of variance (introduced by the 21-day sampling and the chemical analysis) for the air concentrations of three PAHs and three PCBs, calculated using the PRC data, was 28-46%. Thus, the PRCs had a high ability to predict site effects of wind and assess the actual sampling situation. Comparison between protected and unprotected SPMDs showed that the sampler design reduced the wind-speed inside the devices and thereby the uptake and release rates.     

Induced low temperature catalytic ignition by transient changes in the gas composition

The effect of gas composition changes on the low temperature activity for supported platinum model catalysts has been studied. By introducing well-controlled periodic O₂ pulses to a simple diluted gas mixture of CO and O₂, a substantial improvement of the low temperature oxidation activity was observed. The reason for low activity on noble metals at low temperatures is often attributed to self-poisoning by CO. The improved catalytic performance observed is proposed to origin from the transients causing a surface reactant composition that is favourable for the reaction rate, i.e. lower degree of self-poisoning. This was also confirmed by in situ Fourier transform infrared (FT-IR) spectroscopy in combination with mass spectrometry (MS) measurements, which gave evidence for the existence of a strong interplay between the gas phase concentration and the adsorbate composition for these catalysts.     

Detection of antineutrophil cytoplasmic antibodies in primary sclerosing cholangitis: a comparison of the alkaline phosphatase and immunofluorescent techniques

SSCP (single-strand conformational polymorphism) is used widely in the field of human biomedicine, but its potential as a population genetics tool for the recovery of nuclear gene genealogies remains to be realized. We describe and illustrate a use for SSCP in the physical isolation of nuclear haplotypes that circumvents several difficulties associated with more conventional cloning procedures. The DNA sequence can be determined directly from the isolated haplotypes and used for phylogenetic inference. SSCP provides a convenient first step toward generating nuclear genealogies for population studies.     

Impaired adipocyte lipolysis in nonobese women with the polycystic ovary syndrome: a possible link to insulin resistance?

The polycystic ovary syndrome (PCOS) is the most common hyperandrogenic disorder among women and is characterized by metabolic and cardiovascular aberrations similar to those seen in the so-called insulin resistance syndrome. The regulation of lipolysis was investigated in isolated abdominal sc adipocytes from 10 nonobese women with PCOS and in 11 age- and body mass index-matched healthy women. Eight PCOS women were reinvestigated after 3 months of treatment with combined oral contraceptives containing ethinyl estradiol and norethisterone, which normalized hyperandrogenicity. The PCOS women showed a marked resistance to the lipolytic effect of noradrenaline due to defects at two different levels in the lipolytic cascade: first, a 7-fold reduction in sensitivity to the beta 2-selective agonist terbutaline (P < 0.005), which could be ascribed to a 50% lower beta 2-adrenoceptor density (P < 0.02) as determined with radioligand binding; there was no difference with regard to dobutamine (beta 1) or clonidine (alpha 2-sensitivity) or beta 1-adrenoceptor density; second, the maximum lipolytic response was also 35% lower (P < 0.02) in the PCOS women compared to that in the healthy women. This was seen with all beta-adrenergic agonists and the postreceptor-acting agents forskolin (activating adenylyl cyclase) and dibutyryl cAMP (activating protein kinase). Neither beta 2-adrenoceptor sensitivity or density nor the reduced lipolytic responsiveness was restored by 3 months of oral contraceptives treatment. The results indicate the existence of a marked impairment of catecholamine-induced lipolysis in nonobese PCOS women displaying early features of the insulin resistance syndrome due to multiple lipolysis defects as a lower beta 2-adrenoceptor density and reduced function of the protein kinase, hormone-sensitive lipase complex. These lipolysis defects are identical to those observed in the insulin resistance (metabolic) syndrome and could be a primary pathogenic mechanism for the development of these disorders.     

Mefloquine and sulfadoxine/pyrimethamine overdose in malaria tropica

Quantitative ultrastructural myocardial changes of myocardium of the japanese quail (Coturnix coturnix japonica) were studied during an immobilization stress (hypodynamia) lasting 9, 30, 60 and 90 days. Hypodynamic quails were fixed by waistcoats to the feeding place simulating conditions of long lasting space flight which the quails were determined for. The surveyed morphological parametres were: mitochondrial rate, mitochondrial volume in % of cytoplasm, volume of myofibres in % of cytoplasm, volume of single mitochondria, extent of cristolysis. Progressive mitochondrial hydratation and even local oedema were observed during the experiment. It led to a progressive increase of mitochondrial volume and simultaneous decrease of volume of myofilaments as a sign of intracellular atrophy of myofibres. The results correlated well with a decreased mass of myofibres observed in experimental quails from space flight on the orbital station MIR.     

Brain monoamine output alterations after a single venlafaxine challenge in experimental hepatic encephalopathy

Venlafaxine (VEN) pharmacokinetics and effects on the brain monoamine output were investigated in the context of experimental hepatic encephalopathy (HE). Systemic VEN (10 mg/kg; subcutaneous) was administered to chronic portacaval shunted (PCS) and sham-operated rats. Their neocortical extracellular levels of 5-HT, 5-HIAA, NA, and DA were then assessed using microdialysis. Serum, brain extracellular, and brain tissue levels of racemic VEN and its main metabolites were also investigated. In a dose-equipotent manner, the VEN challenge increased the 5-HT levels in PCS rats compared with VEN-treated controls, whereas the 5-HIAA levels decreased similarly with time after the challenge in PCS and controls. Brain extracellular NA levels increased similarly in PCS and controls after VEN, but DA increased predominantly in controls. A similar single dose challenge resulted in clearly higher VEN levels in serum, brain extracellular fluid, and brain tissue in the PCS rats compared with controls. However, the VEN brain tissue/serum ratios were in the same order of magnitude for the two groups. Of the main VEN metabolites, only O-desmethylvenlafaxine (ODV) could be detected in pharmacologically significant amounts. The ODV concentration was also elevated in all three investigated biomatrices of the PCS rats versus control rats. The authors concluded that a typical novel brain monoamine-acting drug, such as VEN, exhibits both pharmacokinetic and pharmacodynamic alterations in experimental HE. Accordingly, the results of this study suggest that this frequently used type of drug should be further studied for its potential combined kinetic/dynamic actions in compromised patients with liver impairment.