Biomedical subjects
Publications and source records attributed to J C Schmidt.
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BACKGROUND: In patients with advanced age-related macular degeneration (AMD), massive subretinal hemorrhage may sometimes be the reason for a loss of peripheral vision, leading to a significantly reduced quality of life. PATIENTS AND METHODS: During the years 1995-2001 we operated five eyes (five consecutive patients) with acute massive subretinal hemorrhage extending into all four quadrants and profoundly reduced vision in the fellow eye due to a Junius-Kuhnt macular scar. Within an interval of 1-2 weeks after the bleeding, pars plana vitrectomy with peripheral retinotomy was performed. After the retina was turned upside down and the partially liquified blood was removed, the underlying subfoveal CNV membrane was removed with a vitrectome. Three phakic eyes required additional cataract surgery and IOL implantation. The retina reattached under PFCL and a silicone oil tamponade applied for 3-6 months. RESULTS: The removal of the subretinal hemorrhage was without complications. The size of the subretinal membrane was between 4 and 6 PD with partially fibrovascular tissue. After the membrane was removed, a large central pigment epithelium defect made a macular rotation impossible. Visual acuity of hand motion improved from preoperatively 0.05 to postoperatively 1/35 to 0.1 after a follow-up of 3-6 months. CONCLUSION: In patients with such an extremely reduced visual acuity and visual field, subretinal surgery with removal of the subretinal blood may achieve sufficient vision for the patients' orientation.
PURPOSE: The aim of the study was to compare the accuracy and the reproducibility of scotopic pupil measurements using two different methods. PATIENTS AND METHODS: We developed a simple test to measure scotopic pupil diameters using a narrow slit of light through a green filter of the Haag-Streit slitlamp. A total of 100 eyes from 50 refractive surgery candidates were prospectively examined by 2 independent investigators using both the Colvard pupilometer (Oasis/USA) and Sekundo's slitlamp green light test. Results were compared using all pairwise multiple comparison procedures (Student-Newman-Keuls method, SigmaStat/Jandel Scientific). The mean age of the patients was 36.3 years with a male:female ratio of 16:34. The colour of the iris was considered blue for 36 individuals and brown for the remainder. RESULTS: Reproducibility: the right eye mean pupil diameter using Sekundo's method was 6.4 mm (+/-0.9) measured by both the first (Slit 1R) and the second (Slit 2R) investigator. The left eye mean pupil diameter was 6.5 mm (+/-1) (Slit 1L) and 6.35 mm (+/-1) (Slit 2L), respectively. The following measurements were obtained with the Colvard pupillometer: (Colv1R)=6.25+/-0.85 mm, (Colv2R)=5.99+/-1 mm, (Colv1L)=6.15+/-0.91 mm, (Colv2L)=6.05+/-0.9 mm. There were no statistically significant differences between the two investigators within the same method of examination. Comparability:The data of both investigators were combined to form 4 groups: (Slit R)=6.4+/-0.96 mm, (Slit L)=6.4+/-1 mm, (Colv R)=6.05+/-0.9 mm, (Colv L)=6.1+/-0.93 mm. There was a significant difference ( p=0.024) between the two methods for both right and left eyes. Particularly for large pupils, the slitlamp green light measurements were significantly higher (up to 0.35 mm) than those with Colvard's device. CONCLUSIONS: The slitlamp green light test provides similar reproducibility for the measurement of the scotopic pupil diameter as the commercially available Colvard pupilometer.
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BACKGROUND: Since introduction of brachytherapy using (106)ruthenium plaque therapy for treating malignant choroidal melanomas a number of comparative studies have shown that survival rates are equal between patients who underwent radiation or enucleation. When radiation treatment fails, the patient might be determined to choose removal of the tumor by pars plana vitrectomy. PATIENTS AND METHODS: Between 1995 and 1998 a total number of 48 patients underwent (106)ruthenium plaque irradiation. In 9 patients tumor regression was not sufficient. Two of these nine patients decided explicitly against enucleation and choose to have the tumor removed from within the eye employing pars plana vitrectomy. RESULTS: Intraoperatively, the previously radiated melanoma was easily removed with the vitrectomy cutter without significant bleeding. Postoperative recovery was without complications. Silicone oil removal was carried out in one patient after one year. Vision 9 months and 2.5 years after surgery was 0.2 and 0.02, respectively. The cosmetic results with parallel axis of the globes were very good and one patient gained binocular vision. No recurrent tumor growth was seen so far. Histologically, no mitotic figures were found. CONCLUSION: Malignant choroidal melanomas can be safely removed by pars plana vitrectomy with stable intraocular pressure. Previous radiation therapy alters the tumor, inducing fibrous tissue growth and necrosis of tumor cells. These tissue types are not prone to bleed when they are resected by the vitrectomy cutter. Long time studies have to elucidate the difference in survival rates between patients undergoing enucleation of the eye and patients who chose endoresection of the melanoma by pars plana vitrectomy.
An instrument employing a light addressable potentiometric sensor and a flow-through immunofiltration-enzyme assay system has been developed for the rapid and specific identification of biological warfare (BW) agents. The system has been designed to assay for up to eight agents simultaneously and provides an indication of the absence or presence of a threat within 15 min. Parameters affecting the mixing of the reagents within the instrument's fluidic lines were investigated and optimized. Measurements of blank samples and samples containing Bacillus subtilis spores in the concentration range of 10(4) to 10(6) cfu/ml indicate the limit of detection (LOD) is 3 x 10(3) cfu/ml for B. subtilus. Although the LOD is higher than that of several technologies currently under development, this instrument offers an immediate interim approach for addressing the need to rapidly detect biological warfare agents in the field.
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The biosynthetic replacement of Met residues by selenomethionine (SeMet) facilitates the determination of three-dimensional structure by multiwavelength anomalous diffraction (Yang, W., Hendrickson, W. A., Crouch, R.J., and Satow, Y. (1990) Science 249, 1398-1405). In an effort to examine any biochemical effects due to the replacement of Met residues by SeMet, we chose to compare the kinetic and binding properties of selenomethionyl dihydrofolate reductase with those of the wt enzyme. There are 5 Met residues in Escherichia coli dihydrofolate reductase with 2 located in the Met-20 loop, which is a sequence of residues forming a lid over the active site. Utilizing plasmid pWT8, which affords 10-15% soluble protein as E. coli dihydrofolate reductase, we readily isolated both the SeMet and wt enzymes from E. coli DL41 utilizing a novel purification protocol. Both enzymes exhibited essentially the same kinetic and binding properties, including specific activities (45 mumol/min/mg), Km (7,8-dihydrofolate = 0.39 microM; NADPH = 2.0 microM), kcat (13.5/s), and 1:1 noncovalent inhibitory binding ratios with methotrexate. The inhibitory effects of divalent and monovalent cations on activity were also assessed, with the SeMet-containing enzyme exhibiting a uniformly greater sensitivity than the wt enzyme. We conclude that the biochemical properties of dihydrofolate reductase are virtually unperturbed by SeMet inclusion. Analysis of SeMet dihydrofolate reductase by 77Se nuclear magnetic resonance spectroscopy revealed five distinct resonances, thus indicating the potential value of this technique in employing selenium as a nonperturbing NMR probe of protein structure and function.
An unusual case is presented of a maxillary central incisor with hemorrhagic discoloration that was successfully treated with the thermocatalytic vital bleach technique. This case emphasizes the need for a thorough radiographic and clinical examination to include vitality tests when a patient presents with a discolored tooth.
To define the costs and benefits associated with prolonged mechanical ventilation, we studied retrospectively the records of 137 consecutive patients who required at least 48 h of ventilator support. The patients were physiologically unstable and required intensive care. Causes of respiratory failure included pulmonary diseases, post-operative complications, neuromuscular diseases, cardiac dysfunction, and GI disease. Forty-nine (36%) patients survived the hospitalization, and 38 (28%) patients were alive 3 yr after receiving prolonged mechanical ventilation. The mean total hospital cost was +16,930/patient (U.S. dollars, 1976-1977). The cost-benefit averaged +1826/yr of extended life. These costs varied from +460/yr of extended life for patients with respiratory failure complicating asthma to +8026/yr for patients with cardiac dysfunction. The cost-benefit ratio increased sharply for men older than 56 yr and for women older than 75 yr. These data document the importance of the basic disease process and the patient's age in the cost-benefit relationship.
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The effect of tetraethyl lead (TEL) and restricted food intake on spontaneous locomotor activity in male albino rats was investigated. Forty animals were injected intraperitoneally with 4, 7, 10 or 13 mg/kg body weight of TEL in peanut oil, or a peanut oil placebo. Forty additional animals were food yoked to lead treated animals as a control procedure to hold food intake constant between lead treated and lead free animals. A comparison of pre- and posttreatment measures revealed significant decreases in food intake and increases in activity levels at dosages of 7, 10 and 13 mg/kg of TEL. In addition, food intake and activity were significantly correlated in both lead treated and yoked groups. The issue of factors associated with reduced food intake playing a role in observed activity level increases was raised.
The effect of tetraethyl lead (TEL) on food and water intake in adult male albino rats was studied. Animals received 1, 4, 7, 10, or 13 mg/kg body weight of TELin peanut oil, or a peanut oil placebo, via either intragastric (IG) intubation or intraperitoneal (IP) injection. For food intake, route of administration was a significant factor and, compared to baseline levels, food intake was significantly depressed at dosage levels of 7, 10, and 13 mg/kg for both IP and IG administration. Further, the time course of food intake differed significantly across route of administration. Water intake was also significantly depressed at 7, 10, and 13 mg/kg, but route of administration was not a critical factor. Results were discussed in relation to clinical and experimental data on lead intoxication, and were viewed as severely limiting the utility of employing food and/or water as motivational variables in assessment of behavioral effects linked to TEL poisoning.
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