Propranolol effect on plasma glucose, free fatty acid, insulin, and growth hormone in Graves' disease

A 3-hr glucose tolerance test was performed in 12 thyrotoxic patients before and after propranolol treatment for 30 days (120 mg/day). Plasma glucose, free fatty acid, insulin, and growth hormone levels were determined on each test and compared to each other and against nine clinically healthy volunteers. In eight thyrotoxic patients (subgroup A) an improvement in carbohydrate tolerance was observed after propranolol treatment, along with a fall in the previously elevated fasting FFA; no change in plasma insulin levels was observed. Plasma growth hormone levels were higher than normal both before and after propranolol; however, a 46% glucose-induced suppression was seen in both instances. In the other four patients (subgroup B) (who had had a marked and rapid weight loss) a deterioration of the previously normal glucosnificant changes in insulin levels. Elevated fasting plasma free fatty acids remained so despite propranolol treatment. Plasma growth hormone was higher than normal before and after propranolol; a late suppression (at 120 min) and no suppression at all were seen, respectively. After propranolol treatment, subgroup B had higher plasma free fatty acid than subgroup A in the fasting state and at 30 and 180 min. It is proposed that the improvement or deterioration in carbohydrate tolerance after propranolol treatment might be related to whether or not a satisfactory propranolol-induced lipolytic blockade is achieved, leading to a decrease in plasma free fatty acid levels, improved insulin sensitivity, and better peripheral glucose utilization. Therefore, a uniform dose of propranolol will not always be sufficient to obtain adequate lipolytic blockade, particularly if the thyrotoxic patient has had a marked and rapid weight loss.     

Thermal transpiration of CO2 at high temperature

Thermal transpiration data for CO₂ in the range 50–545°C have been determined following the relative method. Among different equations suggested for the theoretical calculation of this effect, only the Kavtaradze equation agrees well with the experimental data.     

Changes in serum and cerebrospinal fluid enzyme activity after head injury

We studied simultaneously in serum (S) and CSF (L) the enzyme activities of GOT, GPT, LDH, ICDH, MDH, ALD, and CPK in 28 patients with head injuries divided into three groups according to the severity of the trauma. We found a correlation between severity of brain lesion and enzyme activity. The best correlation was found for SGOT, SCPK, LGOT, LLDH, LMDH and LCPK. We do not believe that enzyme activity is of prognostic value. We think that further studies should be made of the specific isoenzymes of the Central Nervous System.     

Long-term accumulation of uranium in bones of Wistar rats as a function of intake dosages

Groups of Wistar rats were fed with ration doped with uranyl nitrate at concentration A ranging from 0.5 to 100 ppm, starting after the weaning period and lasting until the postpuberty period when the animals were sacrificed. Uranium in the ashes of bones was determined by neutron activation analysis. It was found that the uranium concentration in the bones, as a function of A, exhibits a change in its slope at approximately 20 ppm-a probable consequence of the malfunctioning of kidneys. The uranium transfer coefficient was obtained and an analytical expression was fitted into the data, thus allowing extrapolation down to low doses. Internal and localized doses were calculated. Absorbed doses exceeded the critical dose, even for the lowest uranium dosage.     

Porcine pericardial membrane subjected to tensile testing: preliminary study of the process of selecting tissue for use in the construction of cardiac bioprostheses

The durability of cardiac bioprostheses is limited fundamentally by structural failure due to mechanical fatigue and calcification. In the present report, we analyze, using an in vitro hydraulic simulator to test tensile strength, the mechanical behavior of porcine pericardium for the purpose of establishing the criteria for selecting the biomaterial, taking into account both morphological criteria (thickness and homogeneity of the specimens) and mechanical criteria (stress at breaking point), using the epidemiological model of paired samples. The stress at breakage was found to range widely from 24.07 MPa to 100.29 MPa, although we observed no statistically significant differences when comparing the mean results in the different regions and zones of the pericardium being studies. The application of the selection criteria in the present series resulted in an excellent mathematical fit in terms of the stress/elongation (R ² > 0.95), making it possible to establish, by means of linear regression, the prediction of the tensile strength in one zone on the basis of the values observed in its paired specimen. © 2001 Kluwer Academic Publishers     

Effects of pre-heating treatment on the annealing behaviour of cold-drawn fire-refined coppers

The influence of hydrogen, oxygen and lead contents on the thermo-mechanical properties of fire-refined copper has been studied and related to the decrease of its hydrogen and oxygen content by the heat treatment known as pre-heating. Fire-refined coppers contain between 0.5 and 0.7 weight ppm of hydrogen, and usually more than 50 weight ppm of lead. The decrease in the hydrogen contents of this material through pre-heating at their optimal pre-heating temperatures, leads to a strong decrease of their annealing temperature for 30% elongation (_30%). Fire-refined coppers with a lead content higher than 20–50 weight ppm (and preferably higher than 250 weight ppm) exhibit a microstructure before pre-heating with a low number of voids, as compared to the pre-heated fire-refined copper. Pre-heating also caused a decrease of the hydrogen contents to no detectable values and a decrease of the amounts of dissolved oxygen. These results are related to the possibility that lead increases the solubility of hydrogen in copper. Pre-heating at the optimal temperature develops faceted voids and decreases the hydrogen content to undetectable values by its reaction with the dissolved oxygen, thus forming water. This theory is confirmed by the poor results of pre-heating treatment obtained for oxygen-free high-purity copper, oxygen-hydrogen-free fire-refined coppers and coppers with lead contents lower than 20–50 weight ppm.     

Simultaneous Dual Band Transmission Over Multimode Fiber-Fed Indoor Wireless Network

Performance measurements of different combinations of digital enhanced cordless telecommunications packet radio service, global system for mobile communications, universal mobile telecommunication service, and 802.11g (54 Mbps) signals in a dual band configuration transmitted over an indoor wireless network fed by a low-cost 850-nm vertical-cavity surface-emitting laser (VCSEL)-300m multimode fiber link are presented. The feasibility of such a system is demonstrated with error vector magnitude measurements which are within the required specifications     

The Development of a Blend-Sampling Technique to Assess the Uniformity of a Powder Mixture

This article discusses the challenges overcome during the development of a blendsampling technique and the successful validation of the blending operation for a tablet dosage form containing 2% active ingredient. Content uniformity results are discussed for three pilot-scale (15-kg) and seven commercial-scale (150-kg) batches of tablets. Blend and core content uniformity data from the pilot-scale batches were acceptable. For the initial commercial-scale batches, although the tablet core content uniformity data were acceptable, the blend uniformity results were poor. The blend data for these batches had very high mean values, but acceptable relative standard deviations (RSDs). This suggested that the drug was being preferentially sampled by the thief, but in a consistent, reproducible manner. Extensive testing was performed on a commercial-scale development batch to identify potential causes of sampling error. The results of this testing helped define the blend-sampling technique and strategy used to validate the mixing operation.     

Improved emitter transit time using AlGaAs-GaInP composite emitterin GaInP/GaAs heterojunction bipolar transistors

A new emitter structure based on composite graded AlGaAs-GaInP approach is described, which allows significant reduction of CBE and improved high-frequency performance. A theoretical study of the composite and conventional emitter HBTs is performed to prove the superiority of composite emitter HBTs using Monte Carlo simulation of their transport properties. The self-aligned HBTs fabricated in this study are grown by CBE with TBA/TBP precursors. The current gain cutoff frequency (f_T) was 62 GHz for the composite emitter design HBT, and 45 GHz for conventional emitter design HBT. The CBE achieved with the composite emitter designs was at least 3 times lower than that of conventional designs and does not show significant variation with collector current. This leads to enhanced f_T characteristics by 15% for composite emitter HBT designs and confirms the theoretical expectations     

Preparation of Aluminum Nitride Thin Films by CVD

AlN films were prepared by CVD using aluminum halide (AlCl₃) and aluminum alkyl ((CH₃)3Al) precursors. The appropriate deposition conditions to obtain polycrystalline AlN films using A1C1₃ precursor were found at T_dep = 1173 K, P_tot = 66.6 Pa and N₂/NH₃ = 0.75. It was found that AlN films of different crystallinity can be obtained from (CH₃)₃Al precursor at T_de = 973-1023 K, P_tot = 1.99 kPa, only under a H₂ atmosphere. AlN films can be grown highly oriented in the (210) direction on amorphous quartz substrates depending on their thicknesses. The 0.1 -0.2 μm thick AlN films were transparent and their refractive indexes were about 1.4-1.6.