Identical resolvases are encoded by Pseudomonas TOL plasmids pWW53 and pDK1.
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Amino Acid Sequence↗
Biomedical subjects
P A Williams
Publications and source records attributed to P A Williams.
Electric and dielectric properties of wet human cortical bone as a function of frequency.
In this paper, the electrical and dielectric properties of wet human cortical bone from a distal tibia were examined as a function of frequency and direction. The resistance and capacitance of the cortical bone specimens were measured at near 100% relative humidity. The measurements were made in all three orthogonal directions at discrete frequencies ranging from 120 Hz to 10 MHz using an LCR meter. At a frequency of 100 kHz, the mean resistivity and specific capacitance for the ten cortical bone specimens were 1.55 k omega-cm and 33.81 pF/cm in the axial direction, 15.79 k omega-cm and 9.98 pF/cm in the circumferential direction, and 21.5 k omega-cm and 9.83 pF/cm in the radial direction. All electrical and dielectric properties except the resistivity and the specific impedance were highly frequency dependent for the frequency range tested. However, the resistivity and specific impedance were relatively less frequency dependent. All electrical and dielectric properties were also transversely isotropic in nature, the values for the axial direction being different from the values obtained for the two transverse directions.
Adult↗
Sequelae of cytomegalovirus pulmonary infections in lung allograft recipients.
Indirect effects of cytomegalovirus (CMV) infections in lung transplant recipients (LTX) have not previously been described in detail. We compared spirometric results, development of chronic rejection, rates of respiratory superinfections, and mortality as long as 2 yr after transplantation, between 62 LTX who never developed CMV (CMV-) and 56 LTX with a history of CMV pulmonary infections (CMV+). Initial spirometric parameters were near identical for both groups, but determinations > or = 6 months after transplantation showed that expiratory flows of the CMV+ were significantly reduced. Actuarial prevalences of chronic allograft rejection (CR) at 2 yr were highest among CMV+ with biopsy-proved pneumonitis (74%) compared with 22% among CMV- (p < 0.038). Bacterial or fungal pneumonias developed in 58.9% of the CMV+, whereas the rate among CMV- was 38.7% (p < 0.05). Only 36% of LTX with CMV pneumonitis lived 2 yr compared with 70% survival for CMV- (p < 0.016). Ganciclovir treatment of CMV infections decreased rates of respiratory superinfections and improved survival of patients, but it did not appear to affect subsequent development of CR. We conclude that CMV pulmonary infections among LTX result in serious late sequelae and that current treatment is ineffectual for prevention of viral-associated CR in these patients.
Adult↗
Barriers and incentives of physicians and patients to cancer screening.
It is imperative that the health care system provide mechanisms to improve cancer control. The most effective way of limiting cancer morbidity and mortality is by prevention (modification of behaviors that increase cancer risk), and by early diagnosis in the asymptomatic stage of the disease, which allows for curative therapies. This article has enumerated barriers that make preventive and early diagnostic maneuvers more difficult for both patients and physicians. Some of the barriers are common to both patients and physicians, such as discontinuity of care. The barriers were discussed from both perspectives. Suggestions were made for modification of these barriers, so that incentives might make provision of the preventive and early diagnosis more likely. The incentives are attainable; however, to make improvements on a large scale will require the efforts of the public, physicians, and the health care system. It will effect physicians from the beginning of their medical education and through their entire practice. A large amount of effort directed at a focused population by a small team of health care workers can make a large difference in preventive care. This was shown effectively by a general practitioner in England who undertook a 15-month "campaign" on a "deprived" community, and raised the level of preventive care to that of an "endowed" community. This type of effort by an individual is desirable, but much smaller individual efforts directed over an entire population can have a much greater ultimate effect. That is why the efforts must be directed toward the primary care physician. These physicians care for the majority of the population, so if each primary care doctor increased current efforts of prevention by just three patients per day, then over the entire population inestimable improvements on preventive care would result. There is some evidence that improvements in preventive care are occurring. As further research is directed at how best to provide preventive services in the physician's office, our skills and effectiveness will improve. Each physician should accept as his or her responsibility the ongoing preventive needs of the population he or she serves. The prevention and early diagnosis of cancer can be coordinated in the office with episodic care to minimize costs. The necessary knowledge and technology are available, application is the key. By applying these in a cost-effective way, we can hopefully attain control of cancer in the next decade.
Attitude of Health Personnel↗
Purification of the proteinase from group B streptococci that inactivates human C5a.
We previously reported that group B streptococci (GBS) possess a cell-associated activity that inactivates the chemotactic activity generated in zymosan-activated serum by cleaving a specific site within the carboxy termini of C5a and C5adesarg. This inactivates the major chemoattractants for neutrophils that are generated when serum complement is activated. We now report the isolation of the enzyme responsible for the proteolytic cleavage of C5a. Treatment of GBS with mutanolysin, an endo-N-acetyl muramidase, released activity from GBS which destroyed the functional activity of C5a. The soluble activity was purified to homogeneity by hydroxyapatite, ion-exchange and gel-filtration chromatography. Analysis by SDS-PAGE showed that the enzyme (GBS C5a-ase) has an Mr of approx. 120,000. The GBS C5a-ase appears to be a serine esterase on the basis of its sensitivity to di-isopropyl fluorophosphate. This enzyme is distinct from the C5a-cleaving enzyme produced by group A streptococci, since the two bacterial products migrate differently on SDS-PAGE, and lack antigenic cross reactivity. This enzyme may play a role in the pathogenesis of group B streptococcal disease through its ability to rapidly inactivate the potent neutrophil agonist, C5a, at sites of infection.
Adhesins, Bacterial↗
Effect of sugars and polyols on water in agarose gels.
Effects of ribose, glucose, sucrose, ethylene glycol, glycerin, propylene glycol, and sorbitol on water in concentrated agarose gels were studied by differential scanning calorimetry at low temperatures. Changes in the phase transition temperatures of 40% agarose gels, induced by the addition of these chemical reagents, are discussed, together with rheological and thermal data for the same systems at ambient and higher temperatures. Both sugars and polyols are believed to reduce the amount of freezable water and to promote plasticization and molecular mobility of agarose chains in gels, thus shifting the glass transition temperatures to lower temperatures. However, the effects of decreasing freezable water, and the direct effect on the junction zones, produced by sugars seem to be different from the effects produced by polyols.
Calorimetry, Differential Scanning↗
A spectrophotometric study of the VO(2+)-glutathione interactions.
The interaction of the vanadyl (IV) cation with reduced glutathione (GSH) has been investigated by electronic absorption spectroscopy, at different metal-to-ligand ratios and pH values. The interaction depends strongly on the initial VO2+/GSH ratio. Starting with a tenfold GSH excess, coordination takes place through the two carboxylate groups of the ligand, generating (at pH = 7) a blue 1:2 VO2+/GSH complex; this stoichiometry could be confirmed by photometric titration experiments. Higher GSH concentrations produce a violet complex, which can also be obtained by addition of GSH to the blue species. Some measurements with the three component amino acids of GSH, as well as results obtained from the VO3-/GSH system, allowed a wider insight into the characteristics of this violet complex, in which the cation interacts with S and N atoms of the peptide.
Amino Acids↗
Duplication of both xyl catabolic operons on TOL plasmid pWW15.
Pseudomonas fluorescens MT15 is the host of the large (250 kbp) TOL plasmid pWW15. We have shown by a combination of hybridization, molecular cloning and enzyme assay that pWW15 carries two distinct regions which share homology with the upper pathway operons (xylCMABN) of other TOL plasmids and two distinct regions which are homologous to the meta pathway operons (xylXYZLTEGFJQKIH) of other TOL plasmids. Both the areas of homology to the upper pathway operons appear to carry all of the structural genes for the three catabolic enzymes of the operon. One of the regions of meta pathway operon homology encodes a complete functional pathway, but the second is incomplete and appears to carry only the genes from xylF downstream.
Catechol 2,3-Dioxygenase↗
Mathematical analysis of catabolic function loss in a population of Pseudomonas putida mt-2 during non-limited growth on benzoate.
Pseudomonas putida mt-2, harbouring the TOL plasmid PWW0, was grown continuously on benzoate in a phauxostat at a non-limited rate. The gradual decrease in the population carrying the complete TOL plasmid was caused predominantly by a growth-rate advantage of spontaneous mutants carrying a partially deleted plasmid (TOL- cells). The growth-rate difference (v) was quantified both by measuring the increase in the dilution rate (from 0.68 to 0.79 h-1; v = 0.11 h-1) and by mathematical analysis of the ingrowth of TOL- cells (v = 0.12 h-1). The latter procedure also established that the segregation rate was of the order of magnitude 10(-5) h-1. Similar values for the growth-rate advantage and the segregation rate were found when both benzoate and succinate were present in non-limiting concentrations. It is suggested that the growth-rate disadvantage of the wild-type strain is caused by inhibitory effects of an intermediate in the degradation of benzoate via the plasmid-encoded meta-pathway.
Benzoates↗
P300 and reaction-time measures in senile dementia of the Alzheimer type.
Auditory evoked potentials were recorded in a choice reaction-time task. This test paradigm elicited the attention-related P300 component and was used to study cognitive processing. Compared with age-matched controls, 17 patients with dementia of the Alzheimer type were shown to have significantly longer reaction times as well as delayed latencies of several components of the auditory evoked potentials. The fractional increase in the reaction times was much greater than that of the P300 peak latency. The latter is commonly accepted as an index of stimulus-evaluation time. These findings suggest a delay in both response selection and stimulus evaluation.
Aged↗
Surgical treatment of overcorrection following radial keratotomy: evaluation of clinical effectiveness.
Secondary hyperopia following radial keratotomy (RK) may result from an initial overcorrection or from a continued effect of the procedure with time. We retrospectively evaluated the effect of surgical intervention for the management of overcorrection following RK in six patients who had undergone reopening of all RK incisions, followed by irrigation and closure of the incisions with 10-0 mersilene sutures. Three patients with prior 4-incision RK, with follow-up of 4 to 26 months, were steepened a mean of 1.63 diopters keratometrically; three patients with prior 8-incision RK, with follow-up of 3 to 12 months, were steepened a mean of 1.46 D keratometrically. Comparison of intraoperative with postoperative keratometry demonstrated a substantial loss of effect with time, which stabilized by 2 months in 4-incision RK patients and by 3 months in 8-incision RK patients. Nevertheless, placement of interrupted sutures across reopened radial incisions consistently induced central corneal steepening in these six patients.
Adult↗
A residency-based information system.
The medical literature has grown to an unmanageable size, and we need to develop information systems that provide better accessibility. An internal medicine residency program is an ideal setting for developing a system in which articles are screened for usefulness in clinical decision making and organized to be rapidly accessible and relatively inexpensive to use. In our residency training program, we use clinical problem-solving, journal club article review, and teaching conference preparation to generate appropriate articles from PAPERCHASE (MEDLINE) database searches. With the chief resident supervising the process, articles are then selected and organized in a computerized article file. The software program, Reference Manager (Research Information Systems, Inc., Encinitas, California), stores article citations and supports searches using standard, medical subject heading vocabulary key words. In an 18-month period, residents have collected more than 1800 references appropriate to clinical decision making and have established an article file that is now used daily as a medical information source.
Abstracting and Indexing↗
Ilizarov external fixation. Surgical principles, nursing implications.
The role of the perioperative nurse in caring for a patient with an innovative procedure such as the Ilizarov device is challenging. Because of the problem fracture, the patient usually has had multiple unsuccessful surgical experiences and may express considerable concern and anxiety. As perioperative patient advocates, nurses must encourage patients to be their own spokespersons and to ask questions when they do not understand. The patient advocacy role becomes even more important when the patient undergoes a new procedure. It is our experience with this procedure that both patients and professional staff have many questions during the postoperative period. It is essential that the perioperative nurse establish a communication climate among the patient and members of the interdisciplinary team that promotes collaboration and problem solving on behalf of the patient undergoing this unique surgical procedure.
Adult↗
The TOL plasmids: determinants of the catabolism of toluene and the xylenes.
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Base Sequence↗
Construction of hybrid xylE genes between the two duplicate homologous genes from TOL plasmid pWW53: comparison of the kinetic properties of the gene products.
The two xylE genes for catechol 2,3-oxygenase, encoded by TOL plasmid pWW53, carry a common SalI restriction site within the reading frame. Each gene was cut at the SalI site and the 5' end of each gene spliced to the 3' end of the other to form hybrid genes, from both of which catalytically active catechol 2,3-oxygenase activities were expressed. The kinetic parameters were determined for the gene products of both the hybrid and the wild-type xylE genes with catechol, 3-methylcatechol and 4-methylcatechol as substrates. Comparison of the results suggested firstly, that the C-terminal regions of the enzymes determined both the binding and the catalytic specificity, and, secondly, that the N-terminal region of one of the enzymic gene products contained a secondary binding site which caused inhibition by excess substrate for methylcatechol substrates but not for catechol. One of the wild-type enzymes appeared to have an intrinsically higher activity for all three substrates than the other. This higher activity depended on the presence of both its C- and N-terminal regions, and in both hybrid enzymes, which contained only one of these regions, activity was significantly reduced.
Binding Sites↗
Electric and dielectric properties of wet human cancellous bone as a function of frequency.
In this study the electrical and dielectric properties of wet human cancellous bone from distal tibiae were examined as a function of frequency and direction. The resistance and capacitance of the cancellous bone specimens were measured at near 100% relative humidity. The measurements were made in all three orthogonal directions at discrete frequencies ranging from 120 Hz to 10 MHz using an LCR meter. At a frequency of 100 kHz, the mean resistivity and specific capacitance for the thirty cancellous bone specimens were 500 ohm-cm and 8.64 pF/cm in the longitudinal direction, 613 ohm-cm and 15.25 pF/cm in the anterior-posterior direction, and 609 ohm-cm and 14.64 pF/cm in the lateral-medial direction. All electrical and dielectric properties except the resistivity and the impedance were highly frequency dependent for the frequency range tested. All electrical and dielectric properties were transversely isotropic as the values for the longitudinal direction were different from values obtained for the two transverse directions and properties in the two transverse directions were approximately similar.
Aged↗
Epikeratophakia: technique modifications and visual results compared to the national study.
Twenty-eight epikeratophakia procedures have been performed at the University of Minnesota since December 1985. This report describes several technique modifications and compares the refractive and visual outcome of these cases with the national results. There have been 17 aphakic cases (13 adult and four pediatric), seven myopic procedures, and four keratoconus cases. Of the adult aphakic cases, 80% were within 3 diopters of emmetropia at six months, with four cases showing an undercorrection. In the myopic group, five cases showed an overcorrection at six months and all patients were within two Snellen lines or better than their preoperative best corrected vision. The major complications included one graft removal for failure to epithelialize, an interface hematoma, and a severe overcorrection to +9.37 diopters in a myopic patient. A no-keratectomy technique was used in the aphakic and myopic groups. A variation on centering the Hessburg-Barron trephine and removing the epithelium was performed and allowed for more accurate trephine placement.
Adult↗
Analysis of astigmatic keratotomy.
Eighty-two keratotomy procedures were performed for both idiopathic and postsurgical astigmatism or myopic astigmatism and analyzed for efficacy using vector and linear regression analysis. Delta keratometry values (delta K) were computed for each case as delta K in the desired axis of effect using vector analysis. Six different procedures were compared including both intersecting and nonintersecting trapezoidal keratotomy, relaxing incisions with compression sutures, T cuts with radial keratotomy, T cuts alone, and RK with elliptical optical zones. Our results showed that the greatest shifts occurred in the trapezoidal groups, whereas the most predictable effects occurred in the relaxing incision/compression suture group. Astigmatic keratotomy is capable of producing large shifts in corneal astigmatism; however, the accuracy of these procedures remains highly variable.
Adult↗