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David White

Publications and source records attributed to David White.

27 records · Page 2Linked to original sources
PubMed2003

Variation in biofilm formation among strains of Listeria monocytogenes.

Contamination of food by Listeria monocytogenes is thought to occur most frequently in food-processing environments where cells persist due to their ability to attach to stainless steel and other surfaces. Once attached these cells may produce multicellular biofilms that are resistant to disinfection and from which cells can become detached and contaminate food products. Because there is a correlation between virulence and serotype (and thus phylogenetic division) of L. monocytogenes, it is important to determine if there is a link between biofilm formation and disease incidence for L. monocytogenes. Eighty L. monocytogenes isolates were screened for biofilm formation to determine if there is a robust relationship between biofilm formation, phylogenic division, and persistence in the environment. Statistically significant differences were detected between phylogenetic divisions. Increased biofilm formation was observed in Division II strains (serotypes 1/2a and 1/2c), which are not normally associated with food-borne outbreaks. Differences in biofilm formation were also detected between persistent and nonpersistent strains isolated from bulk milk samples, with persistent strains showing increased biofilm formation relative to nonpersistent strains. There were no significant differences detected among serotypes. Exopolysaccharide production correlated with cell adherence for high-biofilm-producing strains. Scanning electron microscopy showed that a high-biofilm-forming strain produced a dense, three-dimensional structure, whereas a low-biofilm-forming strain produced a thin, patchy biofilm. These data are consistent with data on persistent strains forming biofilms but do not support a consistent relationship between enhanced biofilm formation and disease incidence.

Animals↗
PubMed2002

Intestinal rather than hepatic microsomal triglyceride transfer protein as a cause of postprandial dyslipidemia in diabetes.

Postprandial dyslipidemia may be a major cause of atherosclerosis in diabetes. Microsomal triglyceride transfer protein (MTP) is essential for the synthesis of the chylomicron particle in the intestine and very low-density lipoprotein (VLDL) in the liver. The purpose of the present study was to examine the effect of diabetes on MTP mRNA expression in a rabbit model of diabetes, which develops atherosclerosis. Male New Zealand white rabbits were fed a 0.5% cholesterol diet. Diabetes was induced with alloxan monohydrate. The lymphatic duct was cannulated and lymph collected for isolation of chylomicrons by ultracentrifugation. Apolipoprotein B48 (apo B48) and apo B100 were separated by polyacrylamide gradient gel electrophoresis and quantified by densitometry. MTP mRNA was determined in liver and intestine by RNase protection analysis, and MTP activity was measured. Diabetic animals had significantly increased plasma triglyceride and decreased high-density lipoprotein (HDL) cholesterol (P <.05). They also secreted more lymph chylomicron apo B48 and apo B100 (P <.05) and more lymph chylomicron total and esterified cholesterol/h (P <.05). Lymph chylomicron particles in the diabetic animals contained significantly less lipid/apo B (P <.05). Intestinal MTP activity and mRNA were significantly higher in diabetic compared with control rabbits (0.07 +/- 0.01 v 0.04 +/- 0.015 fluorescent units/microg microsomal protein and 66 +/- 21 v 37 +/- 11 amol MTP mRNA/microg total RNA (P <.005). There was no difference in MTP activity or mRNA expression in the liver. This study suggests that MTP may play an important role in the postprandial dyslipidemia of diabetes.

Alloxan↗
PubMed2002

Invisible nurses.

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed2002

Removal of anti-Galalpha1,3Gal xenoantibodies with an injectable polymer.

Preformed and elicited Ab's against the Galalpha1,3Gal terminating carbohydrate chains (alphaGal Ab's) are the primary cause of hyperacute and acute vascular xenograft rejection in pig-to-primate transplantation. alphaGal Ab's are produced by long-lived Ab-producing cells that are not susceptible to pharmacological immunosuppression. We reasoned that antigen-specific elimination of alphaGal Ab's might be achieved in vivo by systemic administration of nonimmunogenic polyvalent alphaGal structures with high avidity for alphaGal Ab's. We devised GAS914, a soluble trisaccharide-polylysine conjugate of approximately 500 kDa that effectively competes for alphaGal binding by alphaGal IgM (IC(50), 43 nM) and IgG (IC(50), 28 nM) in vitro. Injections of GAS914 in cynomolgus monkeys, at the dose of 1 mg/kg, resulted in the immediate decrease of more than 90% of circulating alphaGal Ab's and serum anti-pig cytotoxicity. In baboons, repeated injections of GAS914 effectively reduced both circulating alphaGal Ab's and cytotoxicity over several months. Studies with [(14)C]GAS914 in rhesus monkeys and Gal(-/-) mice indicate that GAS914 binds to circulating alphaGal Ab's and that the complex is quickly metabolized by the liver and excreted by the kidney. Remarkably, posttreatment alphaGal Ab titers never exceeded pretreatment levels and no sensitization to either alphaGal or the polylysine backbone has been observed. Furthermore there was no apparent acute or chronic toxicity associated with GAS914 treatment in primates. We conclude that GAS914 may be used therapeutically for the specific removal of alphaGal Ab's.

Animals↗
PubMedDate not supplied

Optical reflectance assay for the detection of biofilm formation.

We describe the protocol for an inexpensive and nondestructive optical reflectance assay for the measurement of biofilm formation. Reflectance data are obtained using an Ocean Optics (Dunedin, Florida) USB 2000 spectrometer with a polychromatic light source. A fiber optic cable is used both for illumination and collection, and Ocean Optics OOIBase32 Platinum software is used for preliminary processing of the data. Differences in reflectance data collected at times ranging from 2 to 24 h distinguish between cell attachment and volume growth for two strains of Enterococci. Confocal scanning laser microscopy imaging is used to confirm these results. Phase contrast microscopy images are also obtained in conjunction with reflectance measurements for several different biofilm specimens. The experiments consider biofilm formation on glass and polystyrene substrata, but the method can be used for many other abiotic substrata of interest, both opaque and nonopaque.

Biofilms↗
PubMedDate not supplied

Audit tools for palliative care services: identification of neglected aspects of care.

The purpose of this study was to investigate the extent to which audit of palliative care service occurs nationally in Britain and Ireland. The following items were measured: (1) audit tools employed, (2) aspects of services undergoing audit, (3) changes in practice as a result of audit, and (4) obstacles to conducting some aspects of the audit. Audit practices were surveyed by means of a postal questionnaire distributed to managers of all hospice and palliative care services in the United Kingdom and Republic of Ireland. A 10 percent sample of managers (n = 40) who responded were subsequently interviewed to confirm and elaborate on questionnaire responses. The response rate was 60 percent and was highest for hospices at 68 percent. Of the respondents, 73 percent audit their services. Of those who audit their services, 79 percent changed their service as a result. Although physical aspects of care were audited frequently (61 percent), other core aspects of palliative care that rarely were audited included bereavement care (17 percent), training (13 percent), and psychological and spiritual care (12 percent). Managers indicated that some aspects of care were rarely audited because they considered clinical and organizational aspects of palliative care to be more important. They also stated that they did not have enough time, expertise, or adequate measurement tools. Until the neglected features of palliative care are audited, the full effectiveness of the services remains unknown.

Hospices↗
PubMedDate not supplied

Sellar reconstruction: is it necessary?

BACKGROUND: Sellar reconstruction is practiced routinely during the transsphenoidal approach to pituitary tumor resection. This practice exposes the patient to risks of donor site complications and may interfere with measuring postoperative tumor reduction. We propose that it is not a necessary component of transsphenoidal pituitary surgery in the absence of intraoperative cerebrospinal fluid (CSF) leak. METHODS: A retrospective chart review of 45 cases of minimally invasive pituitary surgery were reviewed. Twenty-eight cases were identified with no sellar reconstruction being performed. Age, sex, revision surgery, postoperative CSF leak, days with lumbar drain, meningitis, ophthalmoplegia, visual acuity loss, postoperative epistaxis, diabetes insipidus, development of empty sella syndrome, and length of stay were investigated in these cases. RESULTS: Twenty-three cases were the primary procedure and five cases were revision surgery. Complication rates were low and compared favorably with those reported in the literature. Five cases of transient diabetes insipidus occurred. There was one postoperative CSF leak that required 4 days with a lumbar drain. No cases of empty sella syndrome developed. There were no cases of meningitis. The average length of stay was 2.9 days. CONCLUSION: Sellar reconstruction during transsphenoidal approach to pituitary tumor resection is not required for patients without evidence of an intraoperative CSF leak. This practice exposes the patient to the risks of donor site complications without reducing the rate of postoperative complications.

Adenoma↗
PubMedDate not supplied

The learning curve in minimally invasive pituitary surgery.

BACKGROUND: Minimally invasive pituitary surgery (MIPS) is performed via an endoscopic transnasal transsphenoidal approach. This provides excellent illumination, visualization, and magnification of the operative field, in addition to avoiding complications associated with other approaches. In this study we examined the first 45 cases of MIPS to determine if a learning curve exists for this technique. METHODS: A retrospective chart review was performed of the first 45 cases of MIPS at a major academic medical center. Cases were divided into three groups of 15 patients each. Group characteristics including age, sex, and revision surgery were compared. Complication rates investigated included death, intracerebral hemorrhage, intraoperative cerebrospinal fluid leak, postoperative cerebrospinal fluid leak, use of lumbar drain, meningitis, postoperative epistaxis, ophthalmoplegia, visual impairment, and diabetes insipidus. Other factors examined included intraoperative blood loss, length of stay, and tumor histology. One way analysis of variance statistical analysis was used to determine the significance of differences between groups. RESULTS: Groups were comparable in respect to characteristics studied. Statistically significant (p < 0.05) differences in complication rates and other factors between groups were not shown. Complication rates are low. CONCLUSION: This study does not establish a learning curve for our first 45 cases of MIPS. This finding supports the concept that an otolaryngology/neurosurgery team skilled in endoscopic techniques and pituitary surgery can safely transition from open approaches to an endoscopic approach in pituitary surgery.

Adult↗