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Biomedical subjects

J H Nelson

Publications and source records attributed to J H Nelson.

At least 37 records · Page 2Linked to original sources
PubMed1989

ESWL treatment of urinary calculi.

A total of 711 patients with symptomatic upper and lower urinary tract calculi underwent extracorporeal shock-wave lithotripsy (ESWL) at the Ohio Kidney Stone Center during the first six months. At follow-up 84 percent of the first 180 patients are stone-free. Retreatment was required for 2.8 percent of the patients with residual stone material. Thirty-seven percent of the treatments required cystoscopy with ureteral stent placement for manipulation of stones or delineation of distal ureteral anatomy to facilitate ESWL. Complications were minimal at less than 3 percent.

Female↗
PubMed1988

Electrochemistry of flavonoids. Relationships between redox potentials, inhibition of mitochondrial respiration, and production of oxygen radicals by flavonoids.

We have investigated the redox behavior of a series of structurally related flavonoids employing cyclic voltammetry under physiological conditions. The flavonoids that auto-oxidized and produced oxygen radicals had oxidation potentials (E 1/2) significantly lower [-30 to +60 mV vs (SCE)] than those that did not undergo auto-oxidation (+130 to +340 mV vs SCE). The range of E 1/2 values for the auto-oxidizable flavonoids was comparable to the E 1/2 range reported for the optimum quinone induced production of superoxide (O2 pi) in mitochondrial NADH-CoQ reductase (complex I). The most potent flavonoid inhibitors of mitochondrial succinate-CoQ reductase (complex II) possessed hydroxyl configurations capable of supporting redox reactions. For a series of 3,5,7-trihydroxyflavones that differed by b-ring hydroxylation it was found that decreasing E 1/2 of the flavonoids was associated with decreasing I50 values towards succinoxidase. These findings suggest that the electrochemical properties of the flavonoids may contribute to their biological activity.

Animals↗
PubMed1988

Effects of screen materials on droplet size frequency distribution of aerosols entering sentinel mosquito exposure tubes.

Aerosol filtration effects of three types of mesh screen used for mosquito cages were evaluated with aerosolized water, mineral oil and chlorpyrifos. The screen materials were two nylon tulles (3 x 4 and 8 x 11 repeats per cm2) and corrosion-resistant steel (7 x 7 repeats per cm2). Open areas of these three mesh materials were, respectively, 94%, 79% and 88%. Aerosol droplet size frequency distributions were altered when passed through test screens of these materials fitted to standard tubes from World Health Organization test-kits for exposure of adult mosquitoes. The alterations included reductions in total droplets and volume median diameter (VmD). Nylon screen with fewer repeats of the mesh altered droplet VmD and frequency distribution the least, allowing the greatest number of droplets to enter sentinel mosquito cages for bioassays of mortality-rates. The greater filtration effect of screens with less open area, giving rise to selective deposition of particular droplet sizes on the screen material, could result in anomalous exposures of test mosquitoes to contact with insecticide filtrate on the screen substrate. This might help to explain the poor correlation often observed between insecticide aerosol impact on wild target mosquito populations as compared with sentinel caged mosquitoes. In addition to other standard test procedures, the need for standardization of materials used for construction of sentinel cages employed for aerosol bioassays is emphasized.

Aerosols↗
PubMed1987

Stented versus nonstented transverse colon conduits: a comparative report.

Postoperative urinary tract complications were evaluated in 75 women who underwent urinary diversion with formation of a transverse colon conduit after radiation for gynecologic cancer. Urinary stents were placed at the ureterocolonic junction in 37 women, while no stents were used in 38 women. Leaks or fistulae developed in 18% of the nonstented group but in only 3% of the stented group (P less than 0.05). Ureteral strictures developed in 18% of the nonstented but in only 8% of the stented group. Pyelonephritis developed in 13% of the nonstented and in 8% of the stented patients. Overall, urinary tract complications developed in 50% of the nonstented and in 16% of the stented group (P less than 0.01). Leaks or strictures developed in 11% of the 75 renal units in the nonstented group but in only 1% of the 72 renal units in the stented group (P less than 0.02). Postoperative leaks or fistulae were associated with further serious complications. Results indicate a significant advantage in employing stents at the ureterocolonic junction in the formation of a transverse colon conduit.

Colon↗
PubMed1987

Health promotion for children. Key to a lifetime of health.

Evidence indicates that preventive healthcare in childhood reduces healthcare costs and enhances health. Physicians can assume a leadership role in promoting children's health by incorporating health promotion measures into their everyday practice, serving as resource persons or leaders in community and school efforts in health promotion, and lobbying for legislation aimed at preventive care. The goals of these efforts are to achieve a healthy childhood, provide a foundation for a healthy adulthood, and develop in children positive values about personal health responsibility and use of healthcare services.

Adolescent↗
PubMed1987

The development and evaluation of a hydrobromic acid-coated sampling tube for measuring occupational exposures to ethylene oxide.

A new sampling method has been developed for the measurement of ethylene oxide (EtO) exposures in the workplace. This sampling method uses a hydrobromic acid-coated charcoal tube to collect EtO as its 2-bromoethanol reaction product. Because 2-bromoethanol is less volatile and less reactive than EtO, improved sampling capacity and sample stability are observed with this method over the collection of EtO on untreated charcoal. Sample analysis is performed by gas chromatography with electron capture detection (GC/ECD) following desorption with dimethylformamide (DMF) and derivatization of the 2-bromoethanol reaction product with heptafluorobutyrylimidazole (HFBI). The direct analysis of 2-bromoethanol by GC/ECD was not reproducible and this effect was attributed to the presence of excess hydrobromic acid (HBr) in the sample. This matrix effect was eliminated by the formation of the heptafluorobutyrate ester, a water-insoluble derivative of 2-bromoethanol, which was extracted into iso-octane for analysis. This analytical scheme is very sensitive and was used to monitor test atmospheres of EtO at the 0.1 ppm level. An average recovery of 96% was obtained for short-term samples (15 minutes) collected from a 5-ppm test atmosphere at 23 degrees C and 80% relative humidity. Similar high recoveries were obtained for 4-hr samples collected at a sampling rate of 0.1 L/min from test atmospheres in the concentration range of 0.1 to 16 ppm EtO at high humidity (80%) and ambient temperature (22 degrees C to 25 degrees C). Samples collected under these same conditions and stored for a minimum of 2 weeks resulted in average recoveries that ranged from 84% to 101%. Average recoveries of 97% were obtained for 2-ppm air samples collected at low humidity with no storage; however, storage of these samples at 22 degrees C to 25 degrees C resulted in an approximate loss of 5% per week. A field comparison study of samples, that was obtained from a hospital sterilization facility, used the test method and the Qazi-Ketchum sample method and resulted in a correlation for paired samples of 0.99 over a concentration range of 0.3 to 7.0 ppm EtO. These results indicate that this sampling and analytical method is a convenient, accurate and reliable means of monitoring EtO exposures in the workplace.

Acids↗
PubMed1987

A new type of collapsible insect-surveillance light trap for sampling Diptera.

The newly designed Army Collapsible Insect Surveillance trap for nocturnal collection of flying Diptera that are attracted by light is described. A polyvinyl chloride construction increases durability, while the capability to collapse from a height of 92.1 cm to 24.1 cm facilitates transportation and storage.

Animals↗
PubMed1986

Management of high-grade stage I adenocarcinoma of the endometrium: hysterectomy following low dose external beam pelvic irradiation.

Sixty-eight patients with FIGO stage I, grade 2 or 3 adenocarcinoma of the endometrium were treated according to a protocol involving 10 Gy external pelvic irradiation, prompt hysterectomy with surgical staging, and postoperative therapy individualized according to surgical-pathologic findings. Five-year survival for the entire group was 78%, 87% for those with grade 2 disease, and 59% for those with grade 3 disease. For patients whose disease was found to be confined to the uterus, surgical stage I, the 5-year survival was 98%. Patients with surgical stage I, grades 2 and 3 disease had 97 and 100% probabilities of surviving 5 years, respectively. Five-year disease-free probability was 96% for all patients with surgical stage I carcinoma, 97% for patients with grade 2 disease, and 94% for patients with grade 3 disease. Myometrial penetration influenced survival; no patient with less than 50% myometrial penetration died or suffered a relapse, while only 40% of patients with deeper penetration survived 5 years. Twenty-three percent of patients with surgically confirmed disease spread beyond the corpus survived 5 years; 29% remained disease-free at this interval. Ten of the 68 patients developed recurrences, none has had a known pelvic recurrence. Two major complications, one requiring surgery, were seen, both in patients receiving postoperative external beam irradiation. The rationale behind low-dose, preoperative external pelvic irradiation is described, and an approach to high-grade, FIGO stage I adenocarcinoma of the endometrium is outlined.

Adenocarcinoma↗
PubMed1986

Production of vinylidene chloride from the thermal decomposition of methyl chloroform.

This study investigated the extent to which methyl chloroform undergoes thermal decomposition to form vinylidene chloride. The experiment was conducted under laboratory conditions that approximate those found in industrial environments. Methyl chloroform vapors at approximately the TLV concentration of 1910 mg/m3 were passed through a heated quartz tube packed with glass or copper beads. In the presence of glass, the decomposition reaction began at 350 degrees C and was essentially complete at 605 degrees C. Vinylidene chloride was detected in nearly stoichiometric amounts. In the presence of copper, the reaction occurred initially at 180 degrees C. At 442 degrees C no methyl chloroform was detected. Once again, the conversion to vinylidene chloride was nearly complete. Two major conclusions have been derived from this study. First, under these experimental conditions, methyl chloroform undergoes thermal decomposition to yield substantial quantities of vinylidene chloride. Second, the dehydrohalogenation reaction proceeds at much lower temperatures in the presence of copper.

Chemical Phenomena↗
PubMed1985

Metabolism of propionate to acetate in the cockroach Periplaneta americana.

Carbon-13 NMR and radiotracer studies were used to determine the precursor to methylmalonate and to study the metabolism of propionate in the cockroach Periplaneta americana. [3,4,5-13C3]Valine labeled carbons 3, 4, and 26 of 3-methylpentacosane, indicating that valine was metabolized via propionyl-CoA to methylmalonyl-CoA and served as the methyl branch unit precursor. Potassium [2-13C]propionate labeled the odd-numbered carbons of hydrocarbons and potassium [3-13C]propionate labeled the even-numbered carbons of hydrocarbons in this insect. This labeling pattern indicates that propionate is metabolized to acetate, with carbon-2 of propionate becoming the methyl carbon of acetate and carbon-3 of propionate becoming the carboxyl carbon of acetate. In vivo studies in which products were separated by HPLC showed that [2-14C]propionate was readily metabolized to acetate. The radioactivity from sodium [1-14C]propionate was not incorporated into succinate nor into any other tricarboxylic acid cycle intermediate, indicating that propionate was not metabolized via methylmalonate to succinate. Similarly, [1-14C]propionate did not label acetate. An experiment designed to determine the subcellular localization of the enzymes involved in converting propionate to acetate showed that they were located in the mitochondrial fraction. Data from both in vivo and in vitro studies as a function of time indicated that propionate was converted directly to acetate and did not first go through tricarboxylic acid cycle intermediates. These data demonstrate a novel pathway of propionate metabolism in insects.

Acetates↗
PubMed1984

Low-dose preoperative radiation therapy for adenocarcinoma of the endometrium. A pilot study.

A pilot study using low-dose preoperative radiation therapy, i.e., 10 Gy in 3 to 4 days as an adjuvant preoperative procedure for grade 2 or 3 (FIGO classification) endometrial carcinoma, was done. The concept of low-dose preoperative radiation therapy is to administer treatment, either surgical or radiotherapeutic, postoperatively according to the surgical and pathologic findings, allowing identification of those patients with previously undiagnosed extensive metastatic disease outside the pelvis found at laparotomy in whom routine pelvic radiation therapy is futile, as well as those patients with relatively low risk of recurrence who may not require further radiotherapy. Forty-four patients with clinical Stage I, grade 2 or 3 with adenocarcinoma of the endometrium were entered into the pilot study. Following surgery, 68% remained Stage I by pathologic examination, and in the remaining patients the stages were changed to II in seven, III in three, and IV in four. Postoperative treatment was administered according to extent of the disease found at surgery. The 4-year actuarial probability of survival rate for the entire group of patients with clinical Stage I disease was 80%; corresponding disease-free rate was 77%. For the Stage I disease confirmed by pathologic examination, the corresponding rate was 96%. The rates for Stages II through IV, as shown by pathologic findings at laparotomy, were 53% and 42%, respectively. In this pilot stud, a treatment policy for clinical Stage I, grade 2 or 3 adenocarcinoma of the endometrium using low-dose preoperative radiation therapy is recommended.

Adenocarcinoma↗