Biomedical subjects
Publications and source records attributed to L W Moore.
Agrobacterium tumefaciens is a soil inhabitant that infects many dicotyledonous plants, causing crown gall disease. The success of Agrobacterium radiobacter K84 to control this disease in agroecosystems throughout the world has been impressive. This review describes the attributes of K84, its mechanism of control, its failures, and other alternative biocontrol agents.
Serological techniques and restriction enzyme cleavage patterns of total DNA were used to differentiate strains of Agrobacterium spp. Forty-five wild-type and plasmid-cured Agrobacterium strains were tested by immunodiffusion and immunofluorescence against polyclonal antisera to a crude ribosome preparation from Agrobacterium strains K84, U11, B6, A323, NT1, and C58. In immunodiffusion gels, these antisera reacted only with water-phenol extracts of the homologous strain, producing a single, strain-specific precipitin line. In contrast, when the same antisera were used in immunofluorescence staining, cross-reactions occurred with a limited number of heterologous Agrobacterium strains. However, the cross-reacting heterologous cells fluoresced generally less brightly than the homologous cells. When the EcoRI-digested DNA profiles from the same Agrobacterium strains were compared, 34 distinct cleavage patterns were observed. The DNA profiles were the same for all strains sharing a common chromosomal background and correlated with the strain-specific serological reaction. The presence or absence of plasmid DNA did not alter the strain-specific serological reaction or the DNA cleavage patterns. Both the serological reaction and the restriction enzyme digestion of total DNA were complementary to each other. These methods were used successfully to identify A. radiobacter K84 strains which were recovered 6 months after being inoculated to young trees in the field.
Populations of agrobacteria in excess of 10 CFU/g were recovered from 12 soil and root samples obtained from the Allison Savanna, Minn., a natural oak savanna and tallgrass prairie which has never been disturbed agriculturally. Of 126 strains picked randomly from selective media, 54 were identified as Agrobacterium spp. Biovar 2 strains predominated (35 of 54), but these strains were distributed into three phenotypically distinct subgroups. Of the remaining Agrobacterium strains, four were biovar 1-2, one was biovar 1, and none were biovar 3. The last 14 Agrobacterium strains formed a homogeneous group which differed biochemically from the hitherto reported biovars. Opine utilization (coded for by genes on the tumor-inducing plasmid in pathogenic Agrobacterium spp.) by these agrobacteria was limited to two biovar 2 strains. In contrast, 10 nonfluorescent gram-negative strains utilized either nopaline or octopine as the sole carbon and nitrogen source. There may be a need to reexamine the source and role of opines in the terrestrial environment because (i) all of these opine utilizers were isolated from an environment free of crown gall, the only known terrestrial source of opines, and (ii) 83% of the opine utilizers were not Agrobacterium spp.
Peritonitis, a major complication of end-stage renal disease patients treated with continuous ambulatory peritoneal dialysis (CAPD), enhances peritoneal protein losses by increasing protein and energy requirements while simultaneously decreasing appetite, usually causing a negative nitrogen balance. The influence of peritonitis on the nutritional status of CAPD patients was evaluated. Fourteen end-stage renal disease patients being treated with CAPD and presenting with peritonitis were randomized to one group with and one without a nutritional supplement. Four CAPD patients without peritonitis served as controls. Anthropometric measurements, laboratory determinations, dietary protein intake, and protein catabolic rate were obtained. The control group lost an average of 9.6 gm protein per 24 hours in the peritoneal fluid vs. an average of 15.1 gm protein per 24 hours lost by patients with peritonitis (p less than .01). Serum albumin did not decrease except in two diabetic patients in whom it dropped an average of 42% and remained low. Nitrogen balance remained positive in all patients except one with diabetes who had very low daily protein intake and caloric intake. The catabolism produced by short uncomplicated peritonitis did not create a negative nitrogen balance in patients eating at least 1 gm protein per kilogram ideal body weight (IBW) and 25 kcal/kg IBW.
We evaluated 15 adult patients with a mean creatinine clearance of 18.35 ml/min and a mean age of 45.7 years. Four patients had glomerulonephritis, two interstitial nephritis and nine had nephrosclerosis. Paired controls were used. Experimental patients were instructed in a diet with 0.55 grams of protein/kilogram body weight/day; the control group was on an unrestricted diet. Protein intake was evaluated with dietary histories. Protein catabolic rates were calculated and were used for reinforcement. Nutritional status was evaluated with anthropometric measurements and laboratory testing. Progression of renal insufficiency was estimated using the reciprocal of the serum creatinine. The mean follow up was 14.9 months. During this period, three patients started dialysis, four had their creatinine clearance remain stable and six improved their renal function 20%. The rate of change of renal function in the treatment group was slower (p less than 0.05) than in the control group. Body weight, anthropometric measurements and chemical parameters did not change significantly. We conclude that a restricted protein diet stabilizes or improves renal function in most patients with end-stage renal failure without producing malnutrition.
Biotype 1 and 2 strains of Agrobacterium tumefaciens were isolated from crown gall tumors of Lippia canescens plants growing as ground cover in Arizona. The isolates were agrocin 84 sensitive, did not catabolize octopine, nopaline, agropine, or mannopine, and were limited in their tumorigenic host range. One biotype 2 strain, AB2/73, showed the most limited host range; it incited tumors only on Lippia strains, the cucurbit family of plants, and Nicotiana glauca. Megaplasmids were detected in the isolates by vertical agarose gel electrophoresis. The unusual host range, as well as sensitivity to agrocin 84, were plasmid specified since they were conjugally cotransferred with plasmids from donor strain AB2/73. Correlation of deletions with concomitant loss of virulence and agrocin 84 sensitivity identified the megaplasmid pAtAB2/73d as the virulence element in strain AB2/73. The estimated size of this tumor-inducing plasmid was 500 kilobases. Axenic growth of tumor tissue incited by strains carrying pAtAB2/73d was phytohormone independent. Although the limited-host-range megaplasmid pAtAB2/73d lacked any detectable homology to the phytohormone-biosynthetic genes in wide-host-range transferred DNA (tms-1, tms-2, tmr), it showed homology to the wide-host-range virB, virC, virD, and virG loci. Therefore, pAtAB2/73d represents a new class of tumor-inducing plasmids distinguished by its large size, the absence of determinants for the catabolism of several known opines, the presence of agrocin 84 sensitivity, and its lack of homology to wide-host-range transferred DNA contrasted with its conservation of sequences from the wise-host-range vir region.
We evaluated the nutritional status of 120 hemodialysis patients using the urea kinetic model. Protein catabolic rate (PCR), an indirect measurement of dietary protein intake, and urea volume of distribution were calculated. Their mid-week predialysis BUN was targeted at 80 +/- 10 mg/dl. The risk factors for chronic hemodialysis patients were analyzed, and since the diabetic patients were unevenly distributed we took them out of the study. This report thus comprises 98 patients distributed in four groups according to their mean PCR and BUN: group 1, mean PCR of 0.63 g/kg/day and BUN of 51 mg/dl; group 2, mean PCR of 0.93 g/kg/day and BUN of 60 mg/dl; group 3, mean PCR of 1.02 g/kg/day and BUN of 79 mg/dl; group 4, mean PCR of 1.2 g/kg/day and BUN of 96 mg/dl. Patients in group 1 had a higher morbidity (number of hospitalizations and number of days in the hospital per patient per year) and a higher mortality (percent per year). The most common causes of hospitalization were infection and congestive heart failure. This group also had an unusually high incidence of pericarditis. Because their risk factors were similar to the other groups, the data suggest that malnutrition was the main cause of these patients' high morbidity and mortality. These patients must be considered at high risk and should be treated aggressively.
An outbreak of metal fume fever (MFF) among workers involved in cutting brass pipes with electric cutting torches in an enclosed, poorly ventilated steam condenser is described. Twenty-six workers were affected. Symptoms most commonly reported were fever (21), dyspnea (23), chills (21), headache (21), and nausea (19). Fourteen of the workers experienced the symptom of an unusual sweet or metallic taste in the mouth. Clinical signs were limited to wheezing or rales in eight patients. Leukocytosis and an increase in band cell forms were noted in 21 and 20 of 24 workers, respectively. The median time interval between exposure and onset of symptoms was five hours. None of three workers who spent less than one hour in the condenser became ill, whereas 25 of 26 of those who spent more than one hour became ill (p = .001). Five of 12 workers had urine copper levels in excess of 0.05 mg/l. To our knowledge, this is the first reported outbreak of MFF for which urinary copper levels have been measured.
Most biotype 2 strains of Agrobacterium tumefaciens and A. radiobacter which utilize nopaline also degrade octopine. In all such strains studied, the ability to degrade octopine did not appear to be transferred to plasmidless recipient cells under conditions of plasmid transfer in which the ability to utilize nopaline was transferred. An octopine-degrading mutant was isolated in a strain cured of its plasmid, suggesting that genes of octopine degradation may have a chromosomal location in some strains. In strains in which octopine utilization is coded by plasmid genes, octopine degradation was always inducible, whereas in strains which degrade both octopine and nopaline, octopine utilization was constitutive although nopaline degradation was inducible. When plasmids coding for octopine-utilizing ability were transformed into a strain containing either a nopaline- or null-type plasmid, transformants able to degrade octopine were either not observed or were unstable upon purification. All of these data suggest that plasmids associated with virulence are incompatible with one another, and therefore imply that the major groups of plasmids associated with virulence have a common origin.
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Macular degeneration, a chronic, progressive eye disease, is the leading cause of blindness in older Americans. As the aging segment of society grows, the number of seniors diagnosed with macular degeneration will increase. Caring for individuals with this disease is a task that will be increasingly allotted to nurses. This article presents information on the disease process, risk factors, medical therapies, and nursing implications involved in caring for individuals with this condition. When nurses gain a thorough understanding of macular degeneration and the implications of living with this disease, quality care can be provided to an expanding segment of society.
Twenty patients treated with human recombinant erythropoietin (EPO) for 9 months were studied. The patients were randomly allocated to high flux (HF) or conventional dialysis (CD). Patients on HF used the F-60 or F-80 dialyzer, with a polysulfone membrane; QB: 470 ml/min; QD: 800 ml/min; t: 127 min; Kt/V: 1.01. Conventional dialysis patients used regenerated cellulosic membranes; QB: 297 ml/min; QD: 500 ml/min; t: 193 min; Kt/V: 1.05. Mean dose of EPO was 103 U/kg for HF patients and 112.4 U/kg for patients on CD. At 9 months, no significant differences were observed in HCT (HF 33.6% vs. CD 33.2%), BUN, serum creatinine, potassium, or phosphorus. Hemoconcentration during dialysis was 12% for HF and 17% for CD. Urea clearance decreased 7% for HF and 9% for CD, while clearance of creatinine, potassium, and phosphorus decreased between 14 and 18% with both treatments. Heparin requirements increased 10% in HF and 16% in CD. Hypertension was similar in both groups. One HF patient withdrew from the study because of hypertension and one HF patient had seizures related to hypertension. Vascular access clotting or hospitalizations were no different. High flux dialysis patients on EPO over a 9 month period did not have any catastrophic complications when HCT was maintained between 30 and 35%.