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Biomedical subjects

D M Williams

Publications and source records attributed to D M Williams.

At least 145 records · Page 8Linked to original sources
PubMed1994

Biodiversity at the molecular level: the domains, kingdoms and phyla of life.

The results of comparative sequence analysis, mainly of small subunit (SSU) ribosomal (r)RNA sequences, have suggested that all of cellular life can be placed in one of three domains: the Archaea, Bacteria or Eucarya. There is some evidence that the Archaea may not be a monophyletic assemblage, but as yet this issue has not been resolved. Most of the lineages, and all of the deepest ones, in the tree based upon SSU rRNA sequences, are microbial. Traditional ideas of classification such as Whittaker's five kingdom scheme do not adequately describe life's diversity as revealed by sequence comparisons. There are many microbial groups that demonstrate much greater amounts of SSU rRNA sequence divergence than do members of the classical kingdoms, Animalia, Plantae and Fungi. The old microbial kingdoms Monera and Protista are clearly paraphyletic but as yet there is no consensus as to how they should be reorganized in taxonomic terms. New data from environmental analysis suggests that much of the microbial world is unknown. Every environment which has been analysed by molecular methods has revealed many previously unrecorded lineages. Some of these show great divergence from the sequences of cultured microorganisms suggesting that fundamentally new microbial groups remain to be isolated. The relationships of some of these new lineages may be expected to affect how the tree of life is organized into higher taxa, and to also influence which features will be recognized as synapomorphies. There is currently no objective measure whereby microbial diversity can be quantified and compared to the figures which are widely quoted for arthropods and other Metazoa.

Animals↗
PubMed1994

The effect of hydroxyethyl starch and other plasma volume substitutes on endothelial cell activation; an in vitro study.

OBJECTIVE: To study the effect of medium molecular weight hydroxyethyl starches on endothelial cell and neutrophil activation in vitro. SETTING: Laboratory analysis. METHODS: The effects of albumin and hydroxyethyl starch on the neutrophil adhesion molecule (CD11bCD18), with and without lipopolysaccharide stimulation, were studied in whole blood. E-selectin expression on human umbilical vein endothelial cells was stimulated with lipopolysaccharide alone and in the presence of either albumin or hydroxyethyl starch. The effect of albumin and hydroxyethyl starches on rapid endothelial cell activation was studied using von Willebrand factor release as a marker. MEASUREMENTS AND RESULTS: Hydroxyethyl starches but not albumin inhibited stimulated vWF release in a dose dependent manner. No effect was seen on endothelial E-selectin or neutrophil CD11bCD18 expression. CONCLUSIONS: these results suggest a possible beneficial role of hydroxyethyl starches in the inhibition of endothelial activation thus preventing neutrophil adhesion during sepsis syndrome.

Cell Adhesion↗
PubMed1994

Simultaneous traumatic ascending and descending thoracic aortic rupture.

A case of a 56-year-old male blunt trauma victim with combined simultaneous ascending and descending thoracic aortic rupture is presented. He was successfully treated with immediate operation for the ascending aortic rupture and a delayed approach, with nonoperative stabilization and later repair, due to poor pulmonary status and a question in diagnosis, for the descending aortic rupture.

Aorta↗
PubMed1994

Pyostomatitis vegetans and associated systemic disease. A review and two case reports.

In this article two case reports of pyostomatitis vegetans are presented. Both cases were associated with inflammatory bowel disease and one case was also associated with liver dysfunction. It has recently been reported that there may be a link between liver dysfunction and pyostomatitis vegetans. The management of the condition is illustrated and the literature on the subject is reviewed.

Adrenal Cortex Hormones↗
PubMed1994

Prevalence and risk factors associated with leukoplakia, hairy leukoplakia, erythematous candidiasis, and gingival hyperplasia in renal transplant recipients.

The aims of this study were to determine the prevalence of intraoral lesions in renal transplant recipients and to identify possible risk factors. The oral mucosa of 159 renal transplant recipients and 160 control patients was examined. The most common lesion in renal transplant recipients was cyclosporin-induced gingival hyperplasia (prevalence 22%) and patients with gingival hyperplasia were found to be taking significantly more cyclosporin-A than those without (p < 0.001). The prevalence of hairy leukoplakia and leukoplakia in renal transplant recipients was 11.3% and 10.7%, respectively, compared with 0% and 5.6% in the controls. Oral candidiasis was observed in 9.4% of renal transplant recipients compared with 2.5% of the controls; 3.8% of renal transplant recipients exhibited erythematous candidiasis, but this was not seen in the controls. Renal transplant recipients had a significantly increased risk of developing gingival hyperplasia (p < 0.0001), oral candidiasis (p < 0.0005), and two other conditions that have a well-established association with the immune suppression accompanying HIV infection, hairy leukoplakia (p < 0.0001) and erythematous candidiasis (p < 0.01).

Alcohol Drinking↗
PubMed1994

Salivary theophylline monitoring: reassessment and clinical considerations.

To assess the reliability of salivary theophylline concentrations for patient monitoring, concentrations of theophylline in sera and saliva of 50 patients (ages 6-81 years) receiving oral or parenteral theophylline were determined by two methods: a rapid dry-phase apoenzyme reactivation system (ARIS) and fluorescence polarization immunoassay (FPIA). Saliva production was stimulated by both citric acid (CA) and parafilm (PF). With both analytical methods, there were excellent correlations between salivary theophylline concentration, CS, and unbound serum theophylline concentration CU (r2 > 0.95), and between CS and total serum theophylline concentration, CT (r2 > 0.85). CA- and PF-stimulated CS by FPIA resulted in concentrations within 2.0 micrograms/ml of the actual CU for 100% of the samples measured (n = 47). By ARIS, 100% of the PF-stimulated CS and 93.6% of the CA-stimulated CS determinations were within 2.0 micrograms/ml of the CU (n = 47). To evaluate the predictive capabilities of PF- and CA-stimulated saliva, one-half (n = 24) of the patients were randomly selected and their data used to predict the CT for the remaining patients. FPIA PF-CS predicted 83.3% (20/24) of CT within +/- 2 micrograms/ml, while ARIS CA-CS predicted 75.0% within +/- 2 micrograms/ml. There was no difference between FPIA CS and ARIS CS results by multivariate analysis of variance (MANOVA), but there was a difference between PF-CS and CA-CS (p < 0.05). However, when CU was used as a covariant, there was no significant difference. Using appropriate saliva collection procedures and the FPIA system, we conclude that CS provides adequate reliability for therapeutic drug monitoring of theophylline.

Adolescent↗
PubMed1994

Retention of low copy number human papillomavirus DNA in cultured cutaneous and mucosal wart keratinocytes.

Cultured wart keratinocytes have previously been described as having a limited proclivity to maintain episomal human papillomavirus (HPV) DNA. To investigate the nature of episome loss, and to determine keratinocyte-specific factors involved in it, we have examined a large series of anogenital and oral wart keratinocyte cultures, tracing episomal copy number with culture passage. We report that a higher proportion of oral wart keratinocytes maintain episomal HPV DNA to first passage (70% compared with 37% of anogenital wart cultures) when screened by slot blot hybridization. Furthermore, oral wart keratinocytes maintain episomal HPV copy through a greater number of passages (60% positive at passage 2 compared with 2% of anogenital wart cultures) with this technique. When anogenital cultures were examined at first passage for HPV infection by PCR with Southern blot hybridization of the product, a further 34% were found to be HPV-positive. To determine the mechanism of loss of episomal DNA from these cultures we examined the relative HPV copy number in cells which adhered to the culture vessel following passage and in those which did not adhere. Those which remained floating contained episomal HPV at high copy number whereas those which adhered were negative by slot blotting. The adherent cells, however, remained positive by PCR at subsequent passages until senescence. We conclude that a subpopulation of HPV-positive keratinocytes may be maintained in culture through serial passage until senescence.

Blotting, Southern↗
PubMed1994

Langerhans cell density in normal human oral mucosa and skin: relationship to age, smoking and alcohol consumption.

The immune function of skin has been studied extensively and it has been suggested that epidermal Langerhans cell (LC) density and function decreases with increasing age. Little is known, however, about the effect of age on oral mucosal LC. Cryostat sections from biopsies of buccal mucosa, lip, hard palate, lateral border of tongue, floor of mouth and abdominal skin, obtained from 91 subjects (aged 16-96 yr), were reacted immunocytochemically with a monoclonal antibody against CD1a and then LC density was expressed as LC/mm epithelial surface length. No significant effect of age on mucosal or skin LC density was found, whilst a history of smoking was associated with an increase in LC density in lateral border of tongue and in biopsies of labial mucosa taken from men (P < 0.05). There was no significant difference between LC density in men and women in oral mucosa. Oral mucosal LC may therefore form a relatively stable population in the adult and thus the increased incidence of mucosal disease in the elderly may be the result of subtle changes in cell mediated immune function rather than changes in LC density.

Adolescent↗
PubMed1994

Serological and microbiological findings on 3 farms with equine leptospiral abortions.

Blood and urine samples from horses on 3 central Kentucky horse farms with prior histories of leptospiral abortions were analysed. Blood samples were obtained from all available horses on each farm and tested for antibodies to 6 leptospira serovars. Urine samples were collected from non-gravid mares with serum antibody titres > or = 1:800 and examined for leptospires by dark-field microscopy, fluorescent antibody testing and culture. Adult horses had the greatest serological evidence of exposure to leptospira, followed by yearlings, then foals. Of horses with anti-leptospiral antibodies, 76.3% reacted against serovar bratislava, 49.1% against icterohaemorrhagiae, 20.1% against grippotyphosa, 16.3% against pomona genotype kennewicki, 15.9% against hardjo and 1.0% against canicola. These findings confirmed that horses in central Kentucky are exposed to multiple leptospira serovars. The seroprevalence of antibodies to the 6 selected serovars was consistent among the 3 selected farms. There was no direct correlation between the serovar that was the cause of abortion in the previous season and prevalence of positive titres to that serovar in horses tested on the farms in the following year. Furthermore, there was no evidence of long-term urinary shedding of leptospira by horses with high leptospira antibody titres.

Abortion, Veterinary↗
PubMed1994

Role for CD8+ T cells in antichlamydial immunity defined by Chlamydia-specific T-lymphocyte clones.

The role of CD8+ T cells in antichlamydial immunity was investigated in a murine model of chlamydial genital infection by using T-cell clones generated against the Chlamydia trachomatis agent of mouse pneumonitis (MoPn). Two CD8+ T-cell clones tested (2.1F and 2.14-9) were chlamydia antigen specific and MHC restricted and reacted against MoPn as well as the Chlamydia psittaci agent of guinea pig inclusion conjunctivitis and C. trachomatis serovar E, suggesting the recognition of a genus-specific antigen. Upon adoptive transfer into persistently MoPn-infected nu/nu mice, 55.6% of the recipients of clone 2.1F (15 of 27) resolved the infection but recipients of clone 2.14-9 did not. The ability to resolve the MoPn infection correlated with the capacity of clone 2.1F to elaborate a combination of gamma interferon and tumor necrosis factor alpha. The results suggested that in addition to CD4+ T cells, CD8+ T cells may also contribute to antichlamydial T-cell immunity in vivo.

Animals↗
PubMed1994

Aortic cobwebs: an anatomic marker identifying the false lumen in aortic dissection--imaging and pathologic correlation.

PURPOSE: To describe and estimate the frequency of fibroelastic cords or bands projecting from the false lumen wall ("aortic cobwebs") in acute and chronic dissections. MATERIALS AND METHODS: Pathologic specimens (n = 23), routine magnetic resonance (MR) images (n = 27), and intravascular (n = 5) and transesophageal (n = 3) ultrasound (US) images from 43 patients with aortic dissection were reviewed, and the presence and configuration of cobwebs were noted. RESULTS: Aortic cobwebs usually bridge the junction of the dissection flap with the outer wall of the false lumen (the line of dissection) but occasionally project like small tendrils from the false lumen wall remote from the line of dissection. Cobwebs were found in 17 of 23 pathologic specimens and on six of 27 MR images, two of five intravascular US scans, and one of three transesophageal US scans. CONCLUSION: Aortic cobwebs most likely represent residual ribbons of media that have been incompletely sheared from the aortic wall during the dissection process. As such, they can serve as an anatomic marker of the false lumen. They are occasionally seen on routine aortic images and may, therefore, prove useful for orientation during percutaneous or surgical interventional procedures to relieve ischemic complications of aortic dissection.

Aortic Dissection↗
PubMed1994

Spiral CT of renal artery stenosis: comparison of three-dimensional rendering techniques.

PURPOSE: To evaluate the accuracy of computed tomographic (CT) angiography in the detection of renal artery stenosis (RAS). MATERIALS AND METHODS: CT angiography was performed in 31 patients undergoing conventional renal arteriography. CT angiographic data were reconstructed with shaded surface display (SSD) and maximum-intensity projection (MIP). Stenosis was graded with a four-point scale (grades 0-3). The presence of mural calcification, poststenotic dilatation, and nephrographic abnormalities was also noted. RESULTS: CT angiography depicted all main (n = 62) and accessory (n = 11) renal arteries that were seen at conventional arteriography. MIP CT angiography was 92% sensitive and 83% specific for the detection of grade 2-3 stenoses (> or = 70% stenosis). SSD CT angiography was 59% sensitive and 82% specific for the detection of grade 2-3 stenoses. The accuracy of stenosis grading was 80% with MIP and 55% with SSD CT angiography. Poststenotic dilatation and the presence of an abnormal nephrogram were 85% and 98% specific, respectively. CONCLUSION: CT angiography shows promise in the diagnosis of RAS. The accuracy of CT angiography varies with the three-dimensional rendering technique employed.

Adult↗
PubMed1994

Teaching multiplication facts to students with learning disabilities: teacher-selected versus student-selected material prompts within the delay procedure.

This study evaluated the effectiveness of the constant time delay procedure, while comparing the efficiency of using teacher-selected and student-selected material prompts, in teaching multiplication facts to 4 male students with learning disabilities ranging in age from 9 years 6 months to 13 years 10 months. The two prompting strategies were compared in the context of a multiple-probe design across groups of multiplication facts, in which the sequence of strategies was counterbalanced across students. Results indicated that although the constant time delay procedure used with material prompts was effective, instruction was more efficient when students were allowed to select the material prompt.

Adolescent↗
PubMed1994

Assessment of interrater and intrarater reliability in the evaluation of metered dose inhaler technique.

STUDY OBJECTIVE: To determine if a training session using videotaped metered dose inhaler (MDI) performances can result in high interrater and intrarater reliability of five evaluators assessing MDI technique. DESIGN: Five evaluators (three pharmacists, two pulmonary fellows) were trained to evaluate MDI technique during a 2-h training session. The training session consisted of verbal instruction and practical experience in evaluating MDI technique using video-taped MDI performances of six nonstudy subjects. After the training session, the evaluators independently observed the same videotaped MDI demonstrations of 14 subjects on two occasions separated by a 7- to 10-day interval. Interrater and intrarater reliability was determined for individual steps by calculating percent agreement and intraclass correlation (ICC) coefficient. RESULTS: Interrater. The interrater reliability for individual steps ranged from 29 to 86 percent (ICC coefficient = 0.13 to 0.81). Steps in which evaluators were in agreement for less than 9 of the 14 subjects were shaking the inhaler before inhalation, exhaling, continuing to inhale slowly, and adequate breath hold. Intrarater: The overall percent agreement by step ranged from 74 to 97 percent. Exhaling to functional residual volume (76 percent) and continuing to inhale slowly and deeply (74 percent) had the lowest overall agreement between the first and second observation day. The consistency of evaluating a step between the two observation days varied considerably depending on the step and evaluator. CONCLUSIONS: High interrater and intrarater reliability in MDI evaluation is difficult to obtain. Clinicians and researchers involved in MDI evaluation and education should be trained to achieve consistency. A single training session using videotaped MDI demonstrations was not adequate in achieving consistency among evaluators. To improve accuracy of research results, researchers should include at least two evaluators to assess MDI technique or take other measures to show and report reliability.

Administration, Inhalation↗
PubMed1994

Aortobronchial fistula 13 years following repair of aortic transection.

We describe a 56-year-old man with the new onset of hemoptysis, increasing in frequency and magnitude, initially diagnosed and treated as pulmonary embolism. Bronchoscopy, computed tomography, and thoracic aortography were performed twice before the diagnosis was made. Thirteen years previously, the patient underwent thoracic aortic interposition graft placement for aortic laceration as a result of a motor vehicle accident. The second aortogram demonstrated a small pseudoaneurysm at the expected proximal graft suture line. Aortobronchial fistula, a rare cause of hemoptysis, was diagnosed. The patient underwent successful resection of the graft and placement of a new dacron interposition graft. All cultures, including blood, sputum, and operative specimen cultures, were negative. The patient is alive and well 1 year following surgery.

Aneurysm, False↗