Biomedical subjects
Publications and source records attributed to D Sanders.
The case of a (69,XXX) triploid infant who survived 160 days is reported. Previously, the longest survival of a non-mosaic triploid had been 9 days. Possible reasons for this extensive survival are discussed.
Two days after an unplanned extra-capsular cataract extraction with sector iridectomy, a patient showed typical signs of bacterial endophthalmitis. Vitreous and aqueous were aspirated for culture, and gentamicin and dexamethasone were injected. Twenty-four hours later, after isolation of Staphylococcus epidermidis, a vitrectomy to remove the central vitreous was done. Postoperatively, vision progressively improved; at the last review nine months after vitrectomy, visual acuity was 20/50.
To determine the toxic effect of whole blood and hemoglobin on the retina, volumes of autogenous blood varying between 0.3 and 1.5 ml and various hemoglobin concentrations were injected intravitreally into speciosa monkeys. Electroretinograms were performed at the outset of the experiment and immediately before sacrifice. After six weeks the animals were killed and the eyes were processed for histologic and electron microscopic examination. Three intravitreal injections of 0.3 ml of autogenous blood administered at one-month intervals or one injection of 22.4 mg of hemoglobin did not produce a toxic effect on the retina demonstrable by light or electron microscopic examination or electroretinography. Intravitreal injection of more than 0.6 ml of whole blood or 40 mg of hemoglobin produced definite toxic effects histologically and electroretinographically. The damage found histologically correlated well with the degree of hemosiderin deposition. Explosive lesions produced by xenon are photocoagulation to induce moderate vitreous hemorrhage failed to produce toxic doses of blood within the eye. In humans undergoing vitrectomy to remove vitreous hemorrhage, the amount of whole blood recovered from vitrectomy fluid was considered nontoxic, except when the patient had massive vitreous hemorrhage or intraoperative bleeding.
Toxicity, clearance, and therapeutic effectiveness of intravitreal vancomycin hydrochloride injection in experimentally induced staphylococcal endophthalmitis were evaluated. Vancomycin was found to be nontoxic in a single, 1 mg/0.1 ml intravitreal dose. Therapeutic levels of vancomycin were present in the vitreous for over 72 hours and in the aqueous during a period from 6 to 48 hours after injection. Injection of a methicillin-resistant Staphylococcus aureus produced a panophthalmitis in our systemically treated controls, whereas in the rabbits treated by intraocular injection, the course of the infection was significantly altered.
Fifteen patients underwent a pars plana approach vitrectomy and membranectomy after acute and chronic injury. In all cases the lens fragments, hemorrhage, and secondary membranes were removed restoring clarity to the ocular media. In two cases the final visual acuity was limited by preexisting retinal injury. The advantages of pars plana approach are the small incision and minimal ocular manipulation during surgery. In the presence of retinal injury, diathermy during the procedure or photocoagulation within 24 hours is also indicated.
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This paper reports the first design and fabrication of a 64 multielectrode array for high-throughput impedance spectroscopy. The purpose of this work is the development of a measurement system for the discovery and improvement of sensor materials using combinatorial methods. An array of interdigital capacitors (IDC) screen-printed onto a high-temperature-resistant Al(2)O(3) substrate is determined to be the optimal test plate. The electrode layout, and therefore also the idle capacity, is determined by specific requirements. Calculation of the idle capacity of the IDC as a function of the electrode width and distance allows adjustment and thus optimization of the array. Parasitic effects caused by the leads and contacts are compensated by a software-aided calibration. Apart from the use of the substrates for discovery of new sensor materials, the presented electrode array is also suitable for electrocatalytic applications as well as impedance spectroscopic studies of semiconductors and dielectrics.
This paper reports on the setup for a high-throughput impedance measurement system that allows rapid screening of the electrical and dielectrical properties of solid-state sample libraries in variable atmospheres and temperatures. Using multielectrode arrays, most time-consuming steps in the workflow are parallelized. In addition, an approach for automated data evaluation of impedance spectra is presented. For reasons of verification of robust measuring results and reproducibility, screening results of a sample library composed of doped indium(III) oxide as a resistive-type gas-sensing material are discussed on the basis of the determined sensitivities focusing temperature and testing gas gradients.
The effect of various surface doping elements on the electrical and gas sensing properties of indium(III) oxide thick films sensors was investigated by means of high-throughput impedance spectroscopy (HTIS). Some doping elements lead to changes in both the conductivity in air as well as in the gas sensing properties towards oxidizing (NO(2), NO) and reducing (H(2), CO, propene) gases. Correlations between the sensing and the electrical properties in reference atmosphere indicate that the effect of the doping elements can be ascribed to an influence on the oxidation state of the metal oxide surface rather that to an interaction with the respective testing gases. An equation for the description of the temperature-dependent conductivity in air and nitrogen is proposed to describe the oxidation state of the metal oxide surface taking into account sorption of oxygen. Furthermore, a model associating the sensing properties and the oxidation state of the surface layer of the metal oxide based on oxygen spillover from doping element particles to the metal oxide surface is introduced.
We present a method for salicylates which is slightly more labor intensive than the usual manual Trinder's test, but is much more sensitive and able to identify individual drugs or metabolites. A 2-mL acidified urine aliquot is briefly extracted with 5 mL ether, and the residue from evaporating the ether under nitrogen is chromatographed on a 250-microns silica gel HPTLC plate using benzene-acetic acid-diethylether-methanol (60:9:30:5) as mobile phase and 5% aqueous ferric chloride as chromogen. The hardiness of the method is evidenced by the Rf values, which vary by no more than 3% over a four-month period. The Rf values are 0.70 for salicylic acid and diflunisal, 0.67 for aspirin and methyl salicylate, 0.60 for gentisic acid, 0.57 for p-aminosalicyclic acid, and 0.40 for salicyluric acid. Detection limits of 1 ppm or less for all the analytes compared favorably to limits of more than 20 ppm for Trinder's test. Separations and spot shapes are sufficiently good to make instrumental quantitation potentially applicable. Sensitivity is sufficient to give clearcut, positive test results 48 h after a single 80-mg dose of ASA by mouth or a 100-mg dose of methyl salicylate by skin injection with a muscle rub, and more than 96 h after a 660-mg oral aspirin dose. Thus, the test is useful for detection and a good degree of differentiation, even in patients using subtherapeutic doses of these salicylates or in those with trace residues from significantly remote full therapeutic or larger doses prior to specimen collections.