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R A Williams

Publications and source records attributed to R A Williams.

At least 73 records · Page 4Linked to original sources
PubMed1996

Testing the value of a measurement protocol for DNA image cytometry and comparing different cytologic preparations.

OBJECTIVE: To analyze the influence of measuring parameters on the quality of DNA histograms, and to compare the results of DNA image cytometry (ICM) and flow cytometry (FCM). STUDY DESIGN: Material from 20 breast cancer cases was analyzed. The protocol for ICM analyzed (1) measuring system and image analysis parameters, (2) the quality of fixation, and (3) the presence of cytoplasm around nuclei. In Feulgen-stained slides (both fresh imprints and cytocentrifuge preparations) at least 200 nuclei were examined using a commercially available ICM system. DNA FCM on disaggregates was performed, also. RESULTS: Strict adherence to the protocol gave reliable DNA ploidy profile results. In contrast, deviations from the protocol gave very broad histograms. With the protocol, similar results were found for imprints and cytocentrifuge samples. Duplicate "blind" assessments were highly reproducible. DNA indices measured by FCM and ICM (on cytocentrifuge samples) correlated highly as well. CONCLUSION: With the protocol used, DNA ploidy profiles obtained by ICM from fresh imprints and cytocentrifuge disaggregate cell preparations were comparable.

Breast Neoplasms↗
PubMed1995

Two different isoschizomers of the type-II restriction endonuclease Taq I (T/CGA) within the same Thermus isolate: Tsp32 I, an enzyme with similar heat stability properties to the prototype enzyme Taq I, and Tsp32 II, a hyperthermostable isoschizomer of Taq I.

We have recently screened 112 separate isolates of the genus Thermus, collected from neutral and alkaline hot water springs on four continents, for the presence of the Type-II restriction endonuclease Taq I (T/CGA). One particular isolate from the Azores (strain 32) was found to contain high levels of a restriction endonuclease with the same recognition and cleavage site as Taq I. Initial studies revealed that the partially purified enzyme from strain 32 was considerably more resistant to heat inactivation than the prototype enzyme Taq I, being able to withstand temperatures at least 10 degrees C higher than Taq I, before showing evidence of heat inactivation. Subsequently it became clear that the partially purified extract from strain 32 contains two separate enzymes, both of which are isoschizomers of Taq I. One of the enzymes, Tsp32 I, has similar thermal stability characteristics to Taq I, whereas the second Taq I isoschizomer, Tsp32 II, found in the same Thermus isolate as Tsp32 I, is considerably more thermostable than Taq I, retaining full enzyme activity up to a temperature of 85 degrees C. Tsp32 I and Tsp32 II were further distinguished by virtue of their different requirements for magnesium ions.

Base Sequence↗
PubMed1995

Taq52 I, a novel and thermostable type II restriction endonuclease from the genus Thermus, recognising the pentanucleotide sequence GC(A or T)GC and cleaving DNA between the first and second bases of the recognition sequence: G decreased or reduced C(A or T)GC.

127 isolates of the genus Thermus, from neutral and alkaline hot water springs on four continents, have been screened for the presence of restriction endonuclease activity. An isolate (YS52) from Yellowstone National Park, USA, showed a high level of restriction endonuclease activity when a cell free extract was incubated with lambda phage DNA at 65 degrees C. A Type II restriction endonuclease (Taq52 I) has been partially purified from this isolate and the recognition and cleavage site determined. Taq52 I has a novel interrupted palindromic tetranucleotide recognition sequence GCWGC, where W can be either adenine (A) or thymine (T). It hydrolyses the phosphodiester bond in both strands of the substrate between the first and second bases of the recognition sequence: 5'G decreased or reduced CWGC3', producing three-base 5'-OH overhangs (sticky ends). The enzyme has a pH optimum of 7.0, requires 8 mM MgCl2 for maximum activity and is thermally stable, retaining full enzyme activity following incubation at 79 degrees C for 10 min. Taq52 I not only represents a new addition to the Type II restriction endonucleases, but also increases the small list of thermostable restriction endonucleases.

Bacteriophage lambda↗
PubMed1995

Two thermostable type II restriction endonucleases from Icelandic strains of the genus Thermus: Tsp4C I (ACN/GT), a novel type II restriction endonuclease, and Tsp8E I, an isoschizomer of the mesophilic enzyme Bgl I (GCCNNNN/NGGC).

Sixteen isolates of thermophilic bacteria from the genus Thermus, isolated from neutral and alkaline hot water springs in the southwest region of Iceland, were tested for the presence of restriction endonucleases. Extracts from five of the isolates showed evidence of the presence of restriction endonuclease activity by producing discrete nucleotide fragments when incubated at 65 degrees C with lambda phage DNA. Two of the isolates (Tsp4C and Tsp8E) were found to have particularly high levels of restriction endonuclease activity, and the respective enzymes from these two Thermus isolates were partially purified and characterized and their recognition and cleavage sites were determined. Enzyme Tsp4C I is a novel Type II restriction endonuclease recognizing the interrupted palindromic tetranucleotide sequence ACNGT, where N can be any one of the four bases in DNA. Tsp4C I, which retains full enzyme activity when incubated for 10 min at temperatures up to 76 degrees C, hydrolyses the phosphodiester bond in both strands of a double-stranded DNA substrate between the third and fourth bases of the recognition sequence (ACN/GT), generating fragments with a single base 3'-OH overhang. Enzyme Tsp8E I is a thermostable isoschizomer of the mesophilic Type II restriction endonuclease Bgl I (GCCNNNN/NGGC) [Lee, Clanton and Chirikjiam (1979) Fed. Proc. 28, 294], generating fragments with a three base 3'-OH overhang. However, unlike Bgl I, Tsp8E I exhibits considerable thermal stability, retaining full enzyme activity when incubated for 10 min at temperatures up to 78 degrees C. Both Tsp4C I and Tsp8E I represent significant additions to the small but expanding list of the extremely thermostable restriction endonucleases.

Base Sequence↗
PubMed1995

Microbial transformation of steroids--IX. Purification of progesterone hydroxylase cytochrome P-450 from Phycomyces blakesleeanus.

Progesterone hydroxylase cytochrome P-450 was purified to homogeneity from Phycomyces blakesleeanus microsomes by a four step procedure. An M(r) value of 60,000 was determined for this protein by SDS-PAGE. The DEAE-cellulose and Blue-1 MIMETIC affinity fractions gave major peaks at 452 nm in a dithionite-reduced, carbon monoxide, difference spectrum. NaIO4-dependent progesterone hydroxylation was obtained by the pure enzyme without NADPH and NADPH-cytochrome P-450 reductase. NADPH-dependent hydroxylation required the addition of other Phycomyces microsomal proteins present in the Blue-1 fraction.

Chromatography, Affinity↗
PubMed1995

Managing choledocholithiasis in the laparoscopic era.

BACKGROUND: Management options for common bile duct stones have explained in the era of laparoscopic cholecystectomy (LC), and selecting the most appropriate method for each patient can be problematic due to the difficulty of predicting accurately which patients have choledocholithiasis (CDL). In order to improve selection of appropriate treatment for CDL, treatment options were analyzed for outcome retrospectively during a 25-month period beginning June 1, 1992. PATIENTS AND METHODS: Four hundred four patients underwent LC; 48 (12%) had CDL identified at preoperative endoscopic retrograde cholangiopancreatography (ERCP) or intraoperative cholangiogram (IOCG). Forty-seven patients were referred for preoperative ERCP for suspected CDL, 23 (49%) of whom had proven duct stones and underwent endoscopic sphincterotomy and stone retrieval with an 87% success rate. RESULTS: Of 357 patients scheduled for LC without preoperative ERCP, 236 had IOCG, of which 25 (11%) demonstrated CDL. Seven patients had open common bile duct exploration (CBDE). Sixteen patients had postoperative ERCP after positive IOCG, 7 (44%) of which were positive for CDL and whose stones were removed with 100% success. Two patients were observed, anticipating spontaneous passage of a small stone. CONCLUSIONS: Preoperative ERCP should be applied selectively. For the large majority of patients without preoperative evidence of CDL, we recommend routine IOCG; if CDL is demonstrated, an intraoperative decision can be made to proceed to postoperative ERCP in the usual case or to open CBDE for very large or multiple stones. Observation in anticipation of spontaneous passage may be appropriate for small, solitary common duct stones. Continuing advances in laparoscopic CBDE are likely to reduce further the need to rely on ERCP in managing CDL.

Cholangiography↗
PubMed1995

Symptoms of depression among female nursing students.

This study examines the extent to which depressive symptoms in female nursing students are affected by specific stressors and coping styles. Three hypotheses were examined for differences in symptoms of depression scores and a model was tested for predicting depression in female nursing students. Responses were gathered from three questionnaires (Hassles and Uplifts Scales, Symptoms of Stress Inventory, and Coping Styles) from 408 female baccalaureate, master's and doctoral students from a major Midwest research university. Symptoms of depression were not significantly different among the students and were as high as a comparative group of stress management clients. Path analysis was used to examine the patterns of stressors (hassles, uplifts, personal and student-related stress), coping (coping styles, habits, quitting school, and drug use), and a biological factor (depression around the menstrual cycle) that predicted symptoms of depression. All hypothesized variables had direct paths to symptoms of depression; the path model explained 58% of the variance. Results from this study support the biological and psychological theories of depression in women and raise important questions of particular relevance to women, nursing students and educators.

Adaptation, Psychological↗
PubMed1995

Multisystemic treatment of serious juvenile offenders: long-term prevention of criminality and violence.

This article examined the long-term effects of multisystemic therapy (MST) vs. individual therapy (IT) on the prevention of criminal behavior and violent offending among 176 juvenile offenders at high risk for committing additional serious crimes. Results from multiagent, multimethod assessment batteries conducted before and after treatment showed that MST was more effective than IT in improving key family correlates of antisocial behavior and in ameliorating adjustment problems in individual family members. Moreover, results from a 4-year follow-up of rearrest data showed that MST was more effective than IT in preventing future criminal behavior, including violent offending. The implications of such findings for the design of violence prevention programs are discussed.

Adolescent↗
PubMed1995

The grouped node technique as a means of handling large electrode surfaces in electrical impedance tomography.

A finite-element method employing a grouped node technique as a means of handling large electrode surfaces in electrical impedance process tomography is presented. The technique groups sets of nodes representing discrete boundary electrodes in a two-dimensional finite-element mesh into corresponding sets of single nodes via a transformation matrix G. The subsequent field solution is obtained based on the new boundary conditions in the standard way after implementing this procedure. Comparison of the resultant boundary voltage profiles from this approach against measurements made on laboratory scale phantoms are reported.

Algorithms↗
PubMed1995

Image analysis DNA densitometry measurements on complete and partial hydatidiform mole and nonmolar products of conception.

Most spontaneous first trimester abortions have an abnormal karyotype, some being triploid; the latter are said to show characteristic histological changes, including focal villous hydropic change, focal trophoblast hyperplasia, cisternal cavitation of larger villi, irregular outline to villi, and trophoblast inclusions. To date, DNA-ploidy profiles have been derived from flow cytometry and cytogenetic karyotyping, both methods being time-consuming and expensive. This study has assessed DNA ploidy on products of conception using a simple video image analysis system. It is concluded that diploid, triploid, aneuploid, and hyperdiploid states can be ascertained on archival paraffin-embedded material using interactive image analysis morphometry. However, the stated histological criteria for triploidy (which has previously been equated with partial mole) appear to be unreliable, with only three of eight histological partial moles having this DNA pattern. In addition, there were six diploid, five triploid, seven hyperdiploid, and two aneuploid DNA ploidy profiles in the spontaneous nonmolar pregnancies. We found that of the 11 complete moles, five were aneuploid and six were hyperdiploid, with none being either diploid or triploid. This finding is contrary to the commonly held view that all complete moles have a diploid DNA profile.

Abortion, Missed↗
PubMed1995

DNA relatedness of Thermus strains, description of Thermus brockianus sp. nov., and proposal to reestablish Thermus thermophilus (Oshima and Imahori)

Aerobic, thermophilic, gram-negative bacteria obtained from Yellowstone National Park that were placed in the genus Thermus on the basis of phenotypic data were examined by chemotaxonomic techniques to determine their peptidoglycan compositions, their respiratory quinones, their mean DNA base compositions, and their levels of DNA-DNA homology as determined by both the filter hybridization and reassociation rate methods. These isolates from hot springs included Thermus aquaticus strains and strains of a new genospecies. We propose the name Thermus brockianus for this new genospecies; strain YS38 is the type strain of this taxon. A collection of 10 strains, including the type strain of "Thermus thermophilus", which were isolated from widely separated geothermal sites, exhibited high levels of DNA-DNA homology with each other and had similar physiological properties. Therefore, we propose that the species Thermus thermophilus (Oshima and Imahori) should be reestablished, with strain HB8 as the type strain.

Base Composition↗
PubMed1995

Evaluation of the Facts on Aging Quizzes I & II.

The Facts on Aging Quizzes (FAQ) I and II (Palmore, 1977, 1981) were designed to assess knowledge and to measure misconceptions regarding the elderly. This study compared results on the FAQ I and II administered to freshmen nursing students. In contrast with Palmore's (1981, 1988) findings, the FAQ I and II were not related (r=.04) and alpha coefficients were low (a=.45 and .32 respectively). However, use of theta coefficients (which make fewer stringent assumptions about items being parallel) resulted in values of .60 and .64 respectively. The factors emerging in this study differed from Palmore's (1977, 1981, 1988) conceptual structure and explained only 45% of the variance. Results from this study suggest that while the FAQ I and II may be useful as a stimulus for discussion, revisions and testing need to be done if they are to be used for research purposes.

Adolescent↗
PubMed1995

Surgical infections in AIDS patients.

Many patients with acquired immune deficiency syndrome (AIDS) and abdominal pain are evaluated by the surgeon, and the majority have gastroenteritis, which can be treated with specific antimicrobials. There are some, however, who need more extensive investigation or who have an intra-abdominal infective process that requires surgical treatment. The one and a half decades of experience with human immunodeficiency virus (HIV) and AIDS has defined the role of the surgeon in treating patients with HIV. Major infective processes that may require surgical involvement include cytomegalovirus infection of the intestinal tract; appendicitis, which may be due to opportunistic infections; spontaneous bacterial peritonitis; cholecystitis; and obstructive jaundice with underlying sclerosis of the biliary tree. Early diagnosis and prompt surgical treatment are critical in the management of HIV-infected patients. For example, cytomegalovirus affecting the gastrointestinal tract may lead to perforation with the development of generalized fecal peritonitis; the clinical presentation of acute appendicitis in HIV patients may not include the usual rise in white blood cell count; and bacterial peritonitis in patients with AIDS may be caused by opportunistic pathogens or, as in the classical case, a single gram-negative bacillus or pneumococcus. This review article focuses on intra-abdominal infections in patients with HIV and AIDS.

Abdominal Pain↗
PubMed1994

Intraoperative measurement of Javid shunt flow with transit-time ultrasound.

Transit-time ultrasound methods were used to measure blood flow in 37 patients undergoing carotid endarterectomy. Internal carotid flow before (ICFbef) and after (ICFaft) endarterectomy was measured with a 6 mm perivascular probe, and Javid shunt flow (SF) was measured with a clamp-on probe. For the entire group ICFbef averaged 117 +/- 67 ml/min and ICFaft was 173 +/- 67 ml/min. Shunt flow averaged 123 +/- 51 ml/min. The differences between ICFbef and ICFaft and between SF and ICFaft were significant (ANOVA, p < 0.01) but the difference between ICFbef and SF was not. The relationship between ICFbef and SF appeared to define two groups of patients. Those in whom SF was greater than ICFbef (SF > ICFbef) had more stenosis evident on preoperative arteriograms (64.7% +/- 14.55% maximum single diameter stenosis) and a greater average increase in ICF (151% +/- 159%) than those with SF < or = ICFbef (43.3% +/- 20.9% stenosis and 34% +/- 54% increase in ICF), suggesting that the relationship between SF and ICFbef defines groups with different hemodynamic responses. The similarity between SF and ICFbef indicates that Javid shunt flow offers adequate protection from cerebral ischemia. A practical benefit of the shunt clamp-on flow probe is the ability afforded to recognize shunt occlusions.

Anastomosis, Surgical↗
PubMed1994

Covalent immobilization of protein monolayers for biosensor applications.

Various sensor technologies require a monolayer of tightly bound proteins. Five methods for protein immobilization were evaluated, comprising two methods of linker attachment to a silicon nitride surface (CNBr, silanization) and three methods of linker attachment to the protein (via primary amines, carboxyl groups, and the aromatic rings of tyrosine and histidine). These covalent binding methods were evaluated by immobilization of the enzyme alkaline phosphatase and with monoclonal antibodies tagged with 125I. It was determined that approximately 75% of the protein on the "covalently" immobilized samples was simply adsorbed. Adsorption was reduced by varying the pH and ionic strength of the wash buffers as well as by adding chaotropes and competitors to the wash buffer. A more efficient method of reducing adsorption was to perform the immobilization in the presence of a detergent; 0.5% Tween 60 was the most effective detergent studied. The optimized procedure gives a surface loading of 1.20 x 10(12) MAb/cm2. of which approximately 10% was adsorbed protein. This surface density is consistent with a monolayer of immobilized protein. This protein was shown to be active by challenging immobilized antibodies with 35S-labelled antigen; only the antibody/antigen pair released radioactive material upon elution.

Antibodies, Monoclonal↗
PubMed1994

Microbial transformations of steroids--VIII. Transformation of progesterone by whole cells and microsomes of Aspergillus fumigatus.

The filamentous fungus, Aspergillus fumigatus, efficiently hydroxylated exogenous progesterone producing, after 3 h of incubation, 11 alpha- and 15 beta-hydroxyprogesterone as major products, 7 beta-hydroxyprogesterone as a minor product and trace amounts of 7 beta, 15 beta- and 11 alpha, 15 beta-dihydroxyprogesterone. After 72 h the dihydroxyprogesterones were the sole metabolites in the culture medium. Microsomes, prepared by Ca2+ precipitation, catalysed only monohydroxylation of progesterone at the same sites as whole cells. Hydroxylation was dependent on NADPH (but not NADH) which was replaceable by NaIO4. Hydroxylation was inhibited by carbon monoxide and by the azole fungicide, ketoconazole. Microsomes gave a dithionite-reduced, carbon monoxide difference absorbance spectrum with a peak at 448 nm and a Type-I progesterone-binding spectrum typical of cytochrome P450 interaction with substrate. Ketoconazole inhibition studies suggest the presence of two non-inducible cytochrome P450 progesterone hydroxylases, one possessing 7 beta site-selectivity, the other 11 alpha/15 beta site-selectivity.

Aspergillus fumigatus↗
PubMed1994

Changes in internal carotid blood flow after carotid endarterectomy correlate with preoperative stenosis.

BACKGROUND: The relationship between preoperative stenosis and the effect of carotid endarterectomy (CEA) upon internal carotid blood flow (ICF) is not well understood. With the intention of better characterizing this, we compared intraoperative measurements of internal carotid blood with the maximum single diameter stenosis found in preoperative angiograms. METHODS: Fifty-two patients undergoing 64 carotid endarterectomies (12 bilateral) had transit-time ultrasound perivascular probes used to measure ICF before and after CEA, and the percent change in ICF (% delta ICF) achieved was calculated. Maximum single-diameter stenosis was determined by comparing the least diameter in the flow path from the common carotid to the normal-appearing internal carotid just distal to bifurcation disease. RESULTS: The entire group had a mean of 53 +/- 21% stenosis found on preoperative angiograms, and % delta ICF averaged 64 +/- 92%. When divided into subgroups based on degree of stenosis, patients with 0% to 40% stenosis (n = 17) had % delta ICF of 32 +/- 46%, patients with 41% to 70% stenosis (n = 30) had % delta ICF of 72 +/- 105%, and patients with more than 70% stenosis had % delta ICF of 168 +/- 160%. The differences in % delta IC were significant for the > 70% group compared with the other groups (analysis of variance, P < 0.005), and marginally significant (P = 0.056) between the 0% to 40% and the 41% to 70% groups. The scatter plot of % delta ICF versus stenosis showed a significant second order direct correlation (r = 0.428, P < 0.001) and disproportionate increases in ICF above 60% stenosis. CONCLUSION: A curvilinear relationship between stenosis and immediate increase in ICF after CEA was demonstrated in agreement with theory, and in those patients with more than approximately 60% single-diameter stenosis, large disproportionate increases in blood flow were more frequently observed.

Analysis of Variance↗