Analysis of secretion and expression of platelet-derived growth factor in cultured endothelial cells from stroke-prone spontaneously hypertensive rat

1. We characterized the endothelial cell-derived growth factors of SHRSP and Wistar Kyoto rats (WKY), respectively and found that platelet-derived growth factor (PDGF)-B chain related growth factor constituted a major portion of the mitogenic activity of the conditioned media of endothelial cells from both animals. There were no remarkable qualitative differences between the endothelial cell-derived growth factors of SHRSP and WKY. 2. Northern analysis revealed that the expression of PDGF-B chain was 2-4-fold enhanced in cultured aortic endothelial cells of SHRSP. This enhanced expression of PDGF-B chain, which may be induced under chronic hypertensive conditions, is suggested to contribute to the increase in endothelial cell-derived growth factors reported in this animal.     

Comparison of gait between young adults fitted with the space foot and nondisabled persons

Prosthetic feet having new keel configurations were specially designed to store deformation energy during early and midstance and release it at push-off. These prosthetic components display longitudinal symmetry favoring good energy storage/release capability in the sagittal plane. The need for inverters/everters either as independent components or within the foot structure has long been recognized. This article documents the walking and slow jogging performances of six young adults wearing below-knee prostheses fitted with the Space Foot, a flexible foot prosthesis that provides medio-lateral control at heel-strike and lateral and forward propulsion at push-off. Results indicate that the Space Foot behaves as a flexible keel foot prosthesis. Its gait performances are also good for fast walking; however, the Space Foot's actual design should be modified if used in sporting activities involving running.     

Solar collectors for the Beirut climate

The performance of solar collector systems is optimized for the Beirut climate with respect to the following parameters: angle of tilt and orientation, plate emissivity and number of glass covers. The Beirut hourly ambient temperature, wind speed, wind direction and the monthly averaged hourly and daily global, beam and diffuse radiation are used in the calculation of the useful harnessed energy, collector's efficiency, storage-tank temperature and other relevant parameters.

The optimal thermal performance of the solar collector in Beirut is obtained for a south-facing collector all the year with a slope angle equal to latitude +15° in winter and latitude −15° in the summer. The use of a selective surface of low emissivity in the collector gives a higher useful energy gain of about 25% in summer and 10% in winter as compared with a nonselective plate surface. The collector's daily efficiency, under optimal conditions, varies from 55 to 65% depending upon the month of the year.     

A quickly reversible occlusion in the vertebrobasilar circulatory bed: often unrecognized?

HISTORY AND FINDINGS: A 29-year-old man presented in another hospital because of discoordination of all extremities with sudden onset. After fast reversal of the symptoms, he was discharged without a clear diagnosis. Because of remaining discrete dysarthria, computed tomography and magnetic resonance imaging were performed which demonstrated bilateral cerebellar infarcts. The cause was assumed to be a transient embolic occlusion of the distal basilar artery. TREATMENT AND COURSE: Intravenous heparin was started to prevent further occlusions. Because no source for emboli or other causes were found, the patient was discharged after 14 days on acetylic acid (250 mg/d) as secondary prevention therapy. CONCLUSIONS: A vascular or neurological cause is often not considered when neurological symptoms are quickly reversible after a transient occlusion of the basilar artery. In these cases, the suspected diagnoses of psychiatric illness, alcohol abuse, drug intoxication, infection or myocardial infarction do not lead to the necessary investigations. Thus, a potentially life-threatening situation may be disregarded.     

Temperature and modulation characteristics of resonant-cavitylight-emitting diodes

Resonant-cavity light-emitting diodes (RCLED) are novel, high-efficiency light-emitting diodes which employ optical microcavities. These diodes have higher intensities and higher spectral purity as compared to conventional LEDs. Analytical formulas are derived for the enhancement of the spontaneous emission along the optical axis of the cavity. The design rules for high-efficiency operation of RCLEDs are established. The temperature dependence of the emission intensity is analyzed in the range 20-80° and it is described by an exponential dependence with a characteristic temperature of 112 K. The modulation characteristics of RCLEDs exhibit 3 dB frequencies of 580 MHz. Eye diagrams at transmission rates of 622 Mb/s are wide open indicating the suitability of RCLEDs for high-speed data transmission     

Characterization of Failure Mechanisms of Duplex and Graded Thermal Barrier Coatings Exposed to Thermal Shock Test

The beginning of failure of a (ZrO2-7%Y2O3)/(Ni-22%Co-17%Cr-12.5%Al-0.6%Y) duplex andgraded coating systems on lnconel 617 and IN738LC in burner rig tests has been characterized.The test conditions are 40 s heating up to 75O℃ substrate temperature followed by 80 s aircooling. Failure is considered at the appearance of the first bright spot during heating period.Stresses due to thermal expansion mismatch strains on cooling are the probable cause of life-limiting in this conditions of testing.     

Hydrogen Reduction and Microstructural Changes of ISF Sinter

The reduction rate and microstructural changes of imperial smelting furnace (ISF) sinter have been investigated by means of thermogravimetric analysis, X-ray difFraction (XRD), scanning electron microscope (SEM ), energy dispersive analysis of X-ray (EDAX) and optical microscope.It is demonstrated that the overall reaction rate of the reduction is influenced by temperature and hydrogen partial pressure in H2 /N2 gas mixtures. There are two distinct zones observed in the partially reduced sinter. The reduction of zincite proceeds predominantly in a narrow range between the two zones, while the reduction of tead oxide and silicate takes place throughout the sinter. The differences between zincite and lead oxide or silicate in reducibility are analysed by thermodynamlcs. The phase transformations and microstructural changes occurring during the reduction process are discussed     

Poly(glycolic acid) fiber-reinforced bioabsorbable composites with improved interfacial properties

Bioabsorbable composites, designed for use as rigid tissue scaffolds, were fabricated by reinforcing free radically cured poly(D,L-lactide) fumarate matrices with absorbable poly(glycolic acid) fibers. To investigate the benefits of an improved fiber/matrix interphase, fiber pretreatments were employed including surface-etching by exposure to mild acidic conditions and incorporation of 3-methacryloxypropyltrimethoxysilane as a coupling agent. SEM of composite fracture surfaces showed that fiber pretreatment yielded improved wetting and encapsulation of the fibers by the matrix resin. The composites fabricated with poly(glycolic acid) fibers which were acid-etched and pretreated with the coupling agent showed an average 41% increase in tensile strength; a representative sample displayed an increase from 73.9 MPa to 105.5 MPa, compared to the composite made from untreated fibers.     

Evaluation of the recombinant 38-kilodalton antigen of Mycobacterium tuberculosis as a potential immunodiagnostic reagent

The diagnosis of infection caused by Mycobacterium tuberculosis is of increased public health concern following increases in the number of cases in developed countries and major increases in developing countries associated with the spread of human immunodeficiency virus (HIV) infection. The specificity of purified protein derivative skin testing for the detection of infection is compromised by exposure to environmental mycobacteria. Examination of sputum detects the most infectious patients, but not those with extrapulmonary disease. The 38-kDa antigen of M. tuberculosis contains two M. tuberculosis-specific B-cell epitopes. We overexpressed the gene for this antigen in Escherichia coli and evaluated the recombinant product in in vitro assays of T-cell function and as a target for the antibody response in humans. The sensitivity and specificity of the antigen as a skin test reagent were also assessed in outbred guinea pigs. We found that 69% of healthy sensitized humans recognize the antigen in vitro, as manifested by both cell proliferation and the production of gamma interferon. Untreated patients initially have a lower frequency of response (38%); this recovers to 72% during therapy. A total of 292 patients (20 with HIV coinfection) and 58 controls were examined for production of antibody to the 38-kDa antigen by using a commercially available kit. The sensitivity of the test in comparison with that of culture was 72.6%, and the specificity was 94.9%. The antigen was also tested for its ability to induce skin reactions in outbred guinea pigs sensitized by various mycobacterial species. The antigen provoked significant skin reactions in M. tuberculosis-, M. bovis BCG-, and M. intracellulare-sensitized animals. The significance of these findings and the usefulness of this antigen in immunodiagnosis are discussed.