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D Brown

Publications and source records attributed to D Brown.

At least 127 records · Page 7Linked to original sources
PubMed2001

Titanium-porcelain system. Part III: effects of surface modification on bond strengths.

During its development, titanium was found to be incompatible with conventional dental porcelains due to weak bond strength brought about by titanium's high yet oxidative nature. In spite of the development of new low-fusing porcelains designed for titanium application, previous studies have shown that sandblasting pre-treatment prior to porcelain application led to weakening of the metal-ceramic bonding. The aim of this study is to search for an effective alternative to sandblasting for the surface treatment of the titanium substrate in the titanium-porcelain system. The research evaluated the bond strength of 165 samples of titanium-porcelain systems divided into 11 groups. A three-point flexural bend test was conducted to measure the force required to fracture the porcelain on the titanium substrate. A correlation between the type of surface treatment and the bond strengths of each group was evaluated if it resulted to significant differences. The study found significantly differences in the energy-to-break of titanium-porcelain systems treated with hydrochloric acid and sandblasting compared with the control group. The bonds strength achieved by the titanium-porcelain system when treated with hydrochloric acid is comparable to that of conventional metal-ceramic alloy system. Hydrochloric acid treatment of the titanium substrate is a promising alternative to sandblasting for the surface treatment of the titanium substrate in the titanium-porcelain system.

Aluminum Oxide↗
PubMed2001

Is participation in cardiac rehabilitation programs associated with better quality of life and return to work after coronary artery bypass operations? The Israeli CABG Study.

OBJECTIVE: To explore the putative effect of cardiac rehabilitation programs on the 'health-related quality of life' and 'return to work' in pre-retirement patients one year after coronary artery bypass grafting. METHODS: Of the 2,085 patients aged 45-64 who survived one year after CABG and were Israeli residents, 145 (6.9%) had participated in rehabilitation programs. Of these, 124 (83%) who answered QOL questionnaires were individually matched with 248 controls by gender, age within 5 years, and the time the questionnaire was answered. All patients had full clinical follow-up including a pre-operative interview. The Short Form-36 QOL questionnaire as well as a specific questionnaire were mailed to surviving patients one year after surgery. Study outcomes included the scores on eight scales and two summary components of the SF-36, as well as 'return to work' and 'satisfaction with medical services' from the specific questionnaire. Analysis was done for matched samples. RESULTS: Cardiac rehabilitation participants had significantly higher SF-36 scores in general health, physical functioning, and social functioning. They had borderline significant higher scores in the physical summary component of the SF-36. The specific questionnaire revealed significantly better overall functioning, higher satisfaction with medical care, and higher rate of return to work. While participants in cardiac rehabilitation and their controls were similar in their socio-demographic and clinical profiles, participating patients tended to be more physically active and more fully employed than their controls. CONCLUSIONS: Rehabilitation participants had a self-perception of better HRQOL, most significantly in social functioning. Our findings of more frequent return to work and higher satisfaction with medical care should induce a policy to encourage participation in cardiac rehabilitation programs after CABG.

Case-Control Studies↗
PubMed2001

[Phage types, plasmid profiles and chromosomal restriction profiles of Salmonella enterica subsp. enterica ser. enteritidis (S. enteritidis) isolated in Poland in 1999-2000].

Salmonella Enteritidis strains are the most often isolated Salmonella serovars in Poland. In the present study, phage typing, plasmid profile analysis, and PFGE have been applied to characterize 140 Polish S. Enteritidis isolates originated from human cases of salmonellosis and from other sources. The typing phages of Ward and colleagues scheme were used to type a total of 140 S. Enteritidis strains coming from Poland. All 140 strains were typable and six different phage types were observed. A total of 125 (89%) of 140 isolates examined belonged to PT 4. The others PTs were represented by small amount of strains (PT1-2, PT6-6, PT7-1, PT8-4 and PT21-2 strains). Among all tested isolates six different plasmid profiles were observed. Of the 140 examined strains, 128 (91.4%) contained the 57 kb plasmid alone. After XbaI digestion four distinct pulse field chromosomal restriction profiles among studied S. Enteritidis were observed. XbaI and SpeI chromosomal restriction profiles of S. Enteritidis PT4 were identical with reference strain profiles. Our findings confirmed earlier suggestions that the increase of human salmonellosis cases in Poland was caused by S. Enteritidis PT4 and was due to consumption of contaminated food. This study confirmed the importance of using PFGE in combination with phage typing, plasmid typing and antibiotic resistance testing for studying the epidemiology of S. Enteritidis.

Bacteriophage Typing↗
PubMed2001

Reciprocating constructed wetlands for treating industrial, municipal and agricultural wastewater.

Scientists at the Tennessee Valley Authority (TVA), and in collaboration with the U.S. Environmental Protection Agency (EPA), are continuing to develop and refine an innovative wastewater treatment system referred to as reciprocating subsurface-flow constructed wetlands. Reciprocation relates to patented improvements in the design and operation of paired subsurface-flow constructed wetlands, such that contiguous cells are filled and drained on a frequent and recurrent basis. This operating technique turns the entire wetland system into a fixed-film biological reactor, in which it is possible to control redox potential in alternating aerobic and anaerobic zones. Reciprocating systems enable manipulation of wastewater treatment functions by controlling such parameters as hydraulic retention time, frequency of reciprocation, reciprocation cycle time, depth of reciprocation, and size and composition of substrate. These improved wetland technologies have been used for treating municipal/domestic wastewater, high strength animal wastewater, and mixed wastewater streams containing acids, recalcitrant compounds, solvents, antifreeze compounds, heavy metals, explosives, and fertilizer nutrients. Results from selected treatability studies and field demonstrations will be summarized with respect to conceptual design and treatment efficacy.

Agriculture↗
PubMed2001

Yellow eyelids heralding lymphoma.

Yellow eyelids are an uncommon finding but can be cosmetically disfiguring to a patient. There are a variety of causes of yellow eyelids. A case study as well as the differential diagnosis of yellow eyelids are presented.

Aged↗
PubMed2001

Observations on the feeding behaviour of Paratrichodorus anemones in relation to tobravirus transmission.

Feeding by P. anemones, an efficient vector of tobacco rattle virus (TRV), was investigated by video-enhanced interference light microscopy. Four stages were observed after transfer of individual nematodes, extracted from soil, to Nicotiana tabacum seedling roots in agar: i) acclimatisation; ii) approach and scrutiny; iii) preparation; and iv) feeding. Prior to commencement of stage 'iv' about 4 cells perforated by rapid onchiostyle thrusting remained alive, each having been almost immediately abandoned by the nematode. During the stage iv) approximately 5% of perforated cells remained alive. Feeding on individual cells was similar to that previously reported for Trichodorus similis: cells from which cytoplasm was ingested after a prolonged period of salivation were invariably killed, with adjacent cells being unaffected. During feeding a number of cells perforated but soon afterwards abandoned by P. anemones remained alive, providing an effective pathway for successful transmission of TRV to plants by the nematode.

Animals↗
PubMed2000

Molecular evidence supports an african affinity of the neotropical freshwater gastropod, Biomphalaria glabrata, say 1818, an intermediate host for Schistosoma mansoni.

Freshwater snails of the genus Biomphalaria, Preston 1910, are the most important and widely distributed intermediate hosts of Schistosoma mansoni, the blood fluke responsible for human intestinal schistosomiasis, in Africa and the Neotropics. S. mansoni is thought to have been imported repeatedly into the Americas during the last 500 years with the African slave trade. Surprisingly considering that the New and Old World separated 95-106 million years (Myr) ago, the disease rapidly became established due to the presence of endemic susceptible hosts. Reconstructing the phylogenetic relationships within Biomphalaria may provide insights into the successful intercontinental spread of S. mansoni. Parsimony and distance analyses of mitochondrial and nuclear sequences show African taxa to be monophyletic and Neotropical species paraphyletic, with Biomphalaria glabrata forming a separate clade from other Neotropical Biomphalaria, and ancestral to the African taxa. A west to east trans-Atlantic dispersal of a B. glabrata-like taxon, possibly as recently as the Plio-Pleistocene (1.8-3.6 Myr ago) according to a general mitochondrial clock, would fit these observations. Vicariance or an African origin for B. glabrata followed by multiple introductions to South America over the past 500 years with the African slave trade seem unlikely explanations. Knowledge of the phylogenetic relationships among important intermediate host species may prove useful in furthering control measures which exploit genetic differences in susceptibility to parasites, and in elucidating the evolution of schistosome resistance.

Africa↗
PubMed2000

The influence of elevated dietary zinc, selenium, and their combination on the suppressive effect of dietary and intraperitoneal cadmium on egg production in laying hens.

The influence of elevated dietary zinc and/or selenium on the suppressive effect of cadmium on egg production in hens has not been previously established. To address this question, two models of cadmium administration were used to differentiate protective effects of zinc or selenium that may result from a reduced absorption of cadmium from those resulting from an elevated nutritional status of these minerals. First, cadmium-induced suppression of egg production was produced in White Leghorn hens using intraperitoneal injections of Cd in order to determine protective effects that result from prefeeding diets supplemented with 803 ppm Zn, 0.91 ppm Se, or their combination relative to a basal diet (control). Feeding elevated dietary selenium throughout the experiment, including a 6-day prefeeding period before Cd administration, resulted in significant protection from the egg suppression produced by 2 injections of cadmium (0.27 mg/kg each) given 1 d apart. Feeding elevated dietary zinc alone or combined with +0.91 ppm Se for a similar period did not markedly protect against cadmium-induced egg suppression. After a 0.54-mg/kg dose of Cd was administered, for a cumulative dose of 1.08 mg/kg, no significant protection was observed from any of the supplemented diets. In a second experiment, the protective effect of the same dietary treatments on the egg-suppressive effect of dietary cadmium was determined. In contrast to cadmium injection, the suppressive effect of 153 ppm dietary cadmium was not mitigated by selenium supplementation, while supplemental zinc protected against this effect of dietary cadmium regardless of the amount of selenium in the diet. There was no significant change in plasma estrogen and vitellogenin levels as a result of cadmium administration in either model, with the exception of significant reduction in both these parameters in the dietary cadmium-exposed birds fed the basal diet. Together, the data suggest that the level of dietary zinc in food sources may be more important in influencing cadmium-induced egg suppression than the nutritional status of zinc in cadmium-exposed birds. In contrast, the nutritional status of selenium in cadmium-exposed birds may have the potential to mitigate this effect, but high exposures to dietary cadmium or zinc may preclude such protection.

Absorption↗
PubMed2000

Molecular epidemiology of a large outbreak of hepatitis B linked to autohaemotherapy.

BACKGROUND: Unregulated skin-piercing procedures potentially facilitate the transmission of bloodborne pathogens. In February, 1998, a patient who had recently received autohaemotherapy at an alternative medicine clinic in the UK was diagnosed with acute hepatitis B. The autohaemotherapy procedure involved the drawing of 1 mL of the patient's blood, mixing with saline, and reinjection of the autologous blood mixture. We investigated the extent of hepatitis B virus (HBV) infection in patients and staff of the clinic. METHODS: Patients who had attended the clinic between January, 1997, and February, 1998, were tested for serological markers of HBV, and for HBV DNA by PCR. HBV DNA was sequenced to assess the relatedness of the virus identified in the cases. We analysed the number and dates of visits with regard to HBV status. FINDINGS: Serum samples were received from 352 patients and four staff members. Serological evidence of exposure to HBV was found in 57 (16%). Of the 33 patients and staff who were positive for hepatitis B surface antigen, 30 (91%) showed complete nucleotide identity in the DNA segments derived from the surface and core genes. Five patients with linked infection had markers of chronic hepatitis B, and one of these was regarded as the likely source of the outbreak. The attack rate was associated with the number of visits (p<0.0001) and the week of visit (p=0.011). Contaminated saline in a repeatedly used bottle was the probable vehicle of transmission. INTERPRETATION: We have described a large community-based outbreak of hepatitis B due to transmission by a single HBV variant. Our findings emphasise the continuing risk of transmission of bloodborne viruses in all health-care settings where skin-piercing procedures are used.

Adult↗
PubMed2000

A new power law for determination of total (125)I seed activity for ultrasound-guided prostate implants: clinical evaluations.

PURPOSE: The intraoperative planning with peripheral loading approach is an important technique for ultrasound-guided transperineal prostate implant. In this paper a sphero-cylindrical dose model is described to generate a new power law or a look-up table for determination of the total (125)I activity required to deliver a prescription dose to a given prostate volume. METHODS AND MATERIALS: Dose calculations were based on the new standards for (125)I seeds (model 6711) implemented by the National Institute of Standards and Technology (NIST) in 1999. Using the sphero-cylindrical dose model with peripheral loading approach, a new power law for calculating total activity of radioactive iodine required to deliver a prescribed dose for the target volume was developed. Accounting for random variation of the seed positioning in the prostate and the current air-kerma strength standard of (125)I seeds, this new power law is formulated as follows: A (mCi) = 2.15 d (cm)(2.00) where A is apparent activity in mCi, or A (U) = 1. 69 d (cm)(2.00) where A is air-kerma strength in U, required to deliver a cumulative dose of 145 Gy to a prostate gland with an average dimension, d, in centimeters. RESULTS: The efficacy of using the new power law in prostate implants was demonstrated. For clinical evaluations of this new power law, 40 patients were chosen in 1998. The average D(90) of these 40 patients was 172.0 Gy (SD +/- 29 Gy). This means that on the average, 90% of the target volume received was 172.0 Gy. The average coverage index (CI) in this study was 94.7 (SD +/- 4.7). As a result, 94.7% of the target volume received the prescription dose. The dose homogeneity index (HI) which measured the degree of the dose inhomogeneity was 0.38 (SD +/- 0.21). CONCLUSION: This new and simple power law or a new mCi-volume look-up table for (125)I seed prostate implantation has been developed and formulated for clinical use. Clinical evaluations expressed in quantitative parameters such as D(90), CI, and HI in prostate implants have been thoroughly analyzed and clearly demonstrated the efficacy of this approach.

Brachytherapy↗
PubMed2000

Expression of P-selectin at low site density promotes selective attachment of eosinophils over neutrophils.

The selective interaction of neutrophils with E-selectin and eosinophils with P-selectin has been previously reported, but the relevance of selectin site density and fluid shear has not been studied in detail. We have developed a new approach to examine these interactions in cell suspensions that integrates an on-line cone-plate viscometer with a flow cytometer. We find that eosinophils and neutrophils both use P-selectin glycoprotein ligand-1 to form stable conjugates with P-selectin Chinese hamster ovary cell transfectants, with a preferential adhesion of eosinophils. Further, the difference in cell adhesion between neutrophils and eosinophils is magnified at P-selectin expression levels below approximately 20 sites/microm2, a range likely to be relevant to endothelial cell expression levels in conditions associated with eosinophilia. The unique behavior is retained over shear rates ranging from 100 to 1500/s but is magnified at low shear. Results from parallel-plate flow chamber assays suggest that preferential eosinophil adhesion reflects an enhanced efficiency of initial PSGL-1 bond formation with P-selectin rather than a unique ability of eosinophils to mediate rolling interactions of longer duration on low-density P-selectin substrates. These differences may account in part for the increase in eosinophil accumulation in allergic diseases.

Animals↗
PubMed2000

The B1 subunit of the H+ATPase is a PDZ domain-binding protein. Colocalization with NHE-RF in renal B-intercalated cells.

The 56-kDa B1 subunit of the vacuolar H(+)ATPase has a C-terminal DTAL amino acid motif typical of PDZ-binding proteins that associate with the PDZ protein, NHE-RF (Na(+)/H(+) exchanger regulatory factor). This B1 isoform is amplified in renal intercalated cells, which play a role in distal urinary acid-base transport. In contrast, proximal tubules express the B2 isoform that lacks the C-terminal PDZ-binding motif. Both the B1 56-kDa subunit and the 31-kDa (E) subunit of the H(+)ATPase are pulled down by glutathione S-transferase NHE-RF bound to GSH-Sepharose beads. These subunits associate in vivo as part of the cytoplasmic V1 portion of the H(+)ATPase, and the E subunit was co-immunoprecipitated from rat kidney cytosol with NHE-RF antibodies. The interaction of H(+)ATPase subunits with NHE-RF was inhibited by a peptide derived from the C terminus of the B1 but not the B2 isoform. NHE-RF colocalized with H(+)ATPase in either the apical or the basolateral region of B-type intercalated cells, whereas NHE-RF staining was undetectable in A-intercalated cells. In proximal tubules, NHE-RF was located in the apical brush border. In contrast, H(+)ATPase was concentrated in a distinct membrane domain at the base of the brush border, from which NHE-RF was absent, consistent with the expression of the truncated B2 subunit isoform in this tubule segment. The colocalization of NHE-RF and H(+)ATPase in B- but not A-intercalated cells suggests a role in generating, maintaining, or modulating the variable H(+)ATPase polarity that characterizes the B-cell phenotype.

Amino Acid Sequence↗
PubMed2000

Urinary morbidity with a modified peripheral loading technique of transperineal (125)i prostate implantation.

PURPOSE: Analysis of urinary morbidity within the first 12 months following a modified peripheral loading technique for permanent transperineal transrectal ultrasound (TRUS) guided (125)I prostate implantation and comparison of urinary morbidity with various clinical and implant parameters. MATERIALS AND METHODS: Between October 1, 1996, and March 11, 1998, 87 patients with favorable, early stage prostate cancer were treated with permanent transperineal TRUS guided (125)I prostate implantation. A peripheral loading technique was utilized for source placement with 75-80% source distribution in the periphery and 20-25% source distribution centrally. A mean total activity of 38 mCi of (125)I was implanted (range, 19-66 mCi). The mean source activity was 0.43 mCi/source (range, 0.26-0.61 mCi/source) and the mean number of sources implanted was 88 (range, 56-134). The minimum prescribed dose to the prostate was 145 Gy. The median D(90), V(100), and V(150) were 152 Gy (range, 104-211 Gy), 92% (range, 71-99%), and 61% (range, 11-89%), respectively. The median follow-up time was 19 months (range, 12-29 months). Urinary morbidity was scored at 3 weeks and then at 3-month intervals for the first 2 years using a modified Radiation Therapy Oncology Group (RTOG) grading system (scale 0-5). RESULTS: Most patients developed at least minor urinary symptoms with frequency or nocturia being the most common. Overall, 79% (69/87) of patients experienced urinary morbidity with 21% (18/87) reporting no symptoms. The incidence of overall Grade 1 urinary morbidity was 37% (32/87); Grade 2 morbidity was 37% (32/87); and Grade 3 morbidity was 6% (5/87). There was no Grade 4 or 5 morbidity. The incidence of Grade 0 frequency/nocturia was 36% (31/87); Grade 1 was 33% (29/87); Grade 2 was 30% (26/87); and Grade 3 was 1% (1/87). Grade 0 dysuria was seen in 56% (49/87) of patients; 32% (28/87) had Grade 1; 10% (9/87) Grade 2; and 1% (1/87) Grade 3 dysuria. Most urinary symptoms started a few weeks after implantation and began to subside by 6 months. At 12 months, 22% (19/87) of patients had persistent urinary symptoms (78% Grade 0, 15% Grade 1, 3% Grade 2, and 3% Grade 3). The mean urethral point dose was 174 Gy (range, 99-315 Gy). The mean number of sources implanted correlated significantly with the likelihood of developing acute urinary morbidity (p = 0.03). The total activity implanted also correlated with the morbidity outcome dysuria (p = 0.01) with a threshold seen at 37 mCi. Urethral point dose, source activity, intraoperative TRUS prostate volume, D(90), V(100), V(150), patient age, pretreatment PSA, Gleason score, and T stage did not correlate with morbidity. CONCLUSIONS: Permanent transperineal TRUS guided (125)I prostate implantation using a modified peripheral loading technique is associated with mild urinary morbidity that resolves in 78% of patients by 12 months. Grade 3 urinary morbidity was encountered in only 6% (5/87) of patients. Urinary morbidity may be related to the total number of sources implanted and/or the total activity implanted. Overall urinary morbidity was not correlated with urethral point dose, source activity, intraoperative TRUS prostate volume, D(90), V(100), V(150), patient age, pretreatment PSA, Gleason score, and T stage. The low incidence of urinary morbidity may be a consequence of our modified peripheral loading technique and/or the selection of patients with good-to-excellent preimplant urological parameters. Longer follow-up is necessary to assess biochemical control rates and long-term morbidity.

Aged↗
PubMed2000

Correlates of HIV infection among young adult short-term injection drug users.

OBJECTIVES: To identify risks associated with HIV infection among young adult short-term injection drug users. METHODS: Current injection drug users, between 18 and 29 years of age, were recruited through street outreach to participate in a cross-sectional survey of HIV prevalence by circumstances of drug injection initiation, HIV-related risk behaviors, and a follow-up to estimate HIV incidence. RESULTS: At enrollment, 33 (14.4%) of 229 participants were HIV-seropositive. Significant bivariate associations with HIV at the time injection drug use was initiated included age less than or equal to 18 years, having receptive anal sex with the person who assisted with initiation, and having two or more 'trainers' before being able to self-inject. Injecting risks positively associated with HIV included cocaine or speedball (heroin and cocaine together) injection versus heroin or amphetamine injection, injecting five or more times per day, daily crack smoking, backloading, sharing needles at peak drug use, and not using a new needle for every injection. Sexual practices associated with HIV included reporting > 100 lifetime sex partners, a history of sexual assault, being gay or bisexual, and trading sex for money or drugs after starting to inject. In a multivariate model, trading anal sex for money or drugs after initiating injection drug use [odds ratio (OR), 14.2; 95% confidence interval (CI) 3.2-62.3], cocaine/speedball injection (OR, 10.3; 95% CI, 2.2-47.9), daily crack smoking (OR, 4.2; 95% CI, 1.7-10.5), and having two or more trainers (OR, 2.6; 95% CI, 1.1 - 5.9) were independently associated with HIV. During 12 months of follow-up, four persons seroconverted for HIV (annual incidence: 2.6%; 95% CI, 1.1 -5.9%) CONCLUSIONS: Among short-term injectors, both sexual and injecting practices were important predictors of HIV infection, indicating that a proportion of HIV infections among young injection drug users can be attributed to sexual transmission. The incidence rate for HIV infection suggests that immediate steps should be taken to prevent new infections among young injection drug users.

Adolescent↗