Preparation and characterization of photoactive composite kaolinite/TiO(2).

Preparation of nanocomposite kaolinite/TiO(2), using hydrolysis of titanyl sulfate in the presence of kaolin was addressed. A variable (kaolin)/(titanyl sulfate) ratio has been used in order to achieve the desired TiO(2) content in prepared nanocomposites. Calcination of the composites at 600 °C led to the transformation of the kaolinite to metakaolinite and to origination of metakaolinite/TiO(2) composites. The prepared samples were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry and diffuse reflectance spectroscopy in the UV-VIS region. Structural ordering of TiO(2) on the kaolinite particle surface was modeled using empirical force field atomistic simulations in the Material Studio modeling environment. Photodegradation activity of the composites prepared was evaluated by the discoloration of Acid Orange 7 aqueous solution.

Flow cytometry: an overview.

Flow cytometry is a method of rapidly analyzing large numbers of cells as they flow in a liquid medium through a laser source. Flow cytometry provides valuable information regarding DNA content, RNA content, and the percentage of cells in the S phase of the cell cycle. This information can be used to predict the aggressiveness of many tumors, which has direct prognostic and diagnostic implications. Flow cytometry assists healthcare professionals in planning and implementing effective, appropriate, and timely interventions. Because flow cytometry is becoming more prevalent, nurses must be aware of its actual and potential applications. The data obtained from flow cytometry provide important information that can assist nurses in anticipating a particular regimen for specific tumors and in projecting the patient's clinical course. With this information, nurses can modify and individualize care plans. When used in conjunction with a patient's clinical presentation and other laboratory findings, flow cytometry has a direct impact on both treatment decisions and nursing interventions.

In vivo platelet aggregation and plasma catecholamines in acute myocardial infarction.

In vivo platelet aggregation assessed with the Filtragometer and potential correlates were compared among (1) patients with acute myocardial infarction (AMI), (2) normal controls, (3) patients with acute chest pain in whom AMI was eventually ruled out (ROMI), and (4) chronic outpatients (Cardiac Clinic group) with a history of myocardial infarction and/or angina pectoris. The measure was independent of sex, age, platelet count, immediate food intake, serum cholesterol, and triglyceride levels. The AMI group showed higher in vivo platelet aggregation than any of the other three groups (p less than 0.01). Least in vivo aggregation was seen in the normal group. Despite lack of correlation with the platelet aggregation measure, plasma epinephrine and norepinephrine showed statistically significant differences between the AMI and each of the other three groups. Our data support an association between platelet function and AMI, although not necessarily a cause and effect relationship.

Glucose concentration at possible sensor tissue implant sites.

It is generally acknowledged that the ideal automatic insulin infusion system would be a closed loop that metered insulin delivery in response to a feedback sensor such as an implantable glucose detector. Most current efforts are aimed at a transducer located within the blood vascular tree. We believe that the blood constitutes an especially hostile environment for such a device. The possibility of placing the sensor with a reasonably rapid response to dynamic alterations in glucose metabolism in a space containing fluid outside the bloodstream was studied. The subcutaneous extracellular space, peritoneum, pleura, and pericardium were included. Generally, the concentration of glucose ranged between 50 and 115 mg/dl under steady-state conditions. The experimental design did not permit monitoring rapid responses to artificially induced dynamic changes. There were several situations where lower values were recorded, suggesting that a wide range of concentrations might occur. The authors have concluded that these experimental results are compatible with the possibility of a suitable locus for the glucose sensor in the extracellular, extravascular space.

Radioimmunoassay for plasma thromboxane B2.

Platelet activity may play a major role in the acute phase of atherosclerotic cardiovascular disease. To assess such activity, an assay for plasma thromboxane B2, a prostaglandin metabolite unique to platelets, is needed. The radioimmunoassay described here is based on a nonequilibrium incubation followed by a solid-phase second-antibody separation of bound from free thromboxane B2. No prior purification is required. Values for 22 normal subjects averaged 39.0 (SD 24.6) ng/L. The thromboxane B2 concentration of a plasma sample was 20.3 ng/L as compared with 37 micrograms/L in the corresponding serum. Plasma thromboxane B2 concentrations before and after ingestion of aspirin differed significantly (p less than 0.025). The biological half-life of intravenously injected [3H]thromboxane B2 in rabbits was 20 min. At the end of 2 h, 85% of the label was accounted for in urine, 7% in liver, and 5% in lung. Our assay is simple, reproducible, sensitive, and specific. It can be used to reflect acute events involving platelet aggregation.