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Biomedical subjects

J T Edwards

Publications and source records attributed to J T Edwards.

8 recordsLinked to original sources
PubMed2001

Extracolonic findings at virtual colonoscopy: implications for screening programs.

OBJECTIVE: Virtual colonoscopy (VC) is an evolving technology proposed as a possible screening tool for colorectal cancer. In contrast to conventional colonoscopy, VC may detect extracolonic abdominal pathology. This may lead to unnecessary investigation of benign lesions, or may benefit the patient by identifying serious pathology at an early stage. The aim of this study was to assess the prevalence and characteristics of extracolonic pathology found in patients undergoing VC. METHODS: A total of 100 patients aged > or = 55 yr, referred for colonoscopy for bowel symptoms or family history of bowel cancer, underwent VC. Axial views of the abdomen were reviewed prospectively by a single radiologist for extracolonic pathology. Patients with extracolonic abnormalities were referred to their local doctor or to a specialist clinic when appropriate. Case records were reviewed and treating doctors contacted to document subsequent investigations and procedures generated. RESULTS: Fifteen patients (15%) had extracolonic abnormalities detected. In four patients, the pathology had been diagnosed previously (umbilical hernia, gallbladder and renal calculi, 3.5-cm aortic aneurysm, ovarian cyst). Eleven patients had new abnormalities detected: ovarian cysts (three), liver cysts (two), uterine fibroids (two), gallstones (one), splenic calcifications (one), aortic aneurysm (one), and renal tumor (one). Two patients with ovarian cysts underwent surgery, and histology showed benign cysts. CONCLUSIONS: Extracolonic abnormalities are common at VC. Most are benign, but may lead to investigative and procedural costs. These data should be carefully evaluated in feasibility and cost-effectiveness studies on colorectal cancer screening using VC.

Aged↗
PubMed2000

Virtual colonoscopy compared with conventional colonoscopy: a developing technology.

AIM: To determine the accuracy of computed tomography colography (virtual colonoscopy) in detecting colorectal polyps and colorectal cancer. DESIGN: Blinded comparison of virtual colonoscopy (initially supine-only scans and later supine plus prone scans) with the criterion standard of conventional colonoscopy. SUBJECTS AND SETTING: 100 patients aged 55 years or over referred to a public teaching hospital for colonoscopy, July 1997 to January 2000, because of colonic symptoms or a family history of bowel cancer. MAIN OUTCOME MEASURES: Presence and size of polyps and other lesions; certainty of polyp identification on virtual colonoscopy (on 100-point visual analogue scale); sensitivity and predictive values of virtual colonoscopy. RESULTS: Conventional colonoscopy identifed 121 polyps in 47 patients; 28 of these polyps, in 19 patients, were identified by virtual colonoscopy. Sensitivity of virtual colonoscopy for detecting polyps (using supine plus prone scans) was 73% for polyps with diameter > or = 10 mm (95% CI, 39%-94%) and 19% for smaller polyps (95% CI, 10%-31%) (P < 0.001); corresponding figures for supine-only scans were 57% (95% CI, 18%-90%) and 11% (95% CI, 4%-24%), respectively. Ten polyps identified at virtual colonoscopy were considered false-positive findings (8%). The value of finding a polyp on virtual colonoscopy (with thresholds of 5 mm for diameter and 30 points for certainty score) was assessed as a predictor of finding a polyp (diameter > 5 mm) on conventional colonoscopy. Positive and negative predictive values were 88% and 89%, respectively, for supine plus prone scans. CONCLUSION: Although virtual colonoscopy shows potential as a diagnostic tool for colorectal neoplasia, it is currently not sufficiently sensitive for widespread use.

Colon↗
PubMed2000

Blood group A and B antigens are strongly expressed on platelets of some individuals.

It is widely thought that expression of ABH antigens on platelets is insufficient to materially affect the survival of ABH-incompatible platelets in transfusion recipients, but anecdotal reports of poor survival of A and B mismatched platelets suggest that this is not always the case. The A and B antigen expression on platelets of 100 group A(1) and group B blood donors was measured, and 7% and 4%, respectively, had platelets whose A and B antigen levels consistently exceeded the mean plus 2 SD. On the basis of flow cytometric and statistical analysis, donors whose platelets contained higher than normal levels of A antigen were subdivided into 2 groups, designated Type I and Type II ("high expressers"). Serum A(1)- and B-glycosyltransferase levels of A and B high expressers were significantly higher than those of group A(1) and B individuals with normal expression. H antigen levels were low on the red cells of high expressers, indicating that the anomaly affects other cell lineages. Immunochemical studies demonstrated high levels of A antigen on various glycoproteins (GPs) from high-expresser platelets, especially GPIIb and PECAM (CD31). The A(1) Type II high-expresser phenotype was inherited as an autosomal dominant trait in one family. The sequences of exons 5, 6, and 7 of the A(1)-transferase gene of one Type II A(1) high expresser and exon 7 from 3 other genes were identical to the reported normal sequences. Further studies are needed to define the molecular basis for the high-expresser trait and to characterize its clinical implications. (Blood. 2000;96:1574-1581)

ABO Blood-Group System↗
PubMed1998

Osteoinduction of human demineralized bone: characterization in a rat model.

The increasing clinical use of human demineralized bone matrix has brought about the desire to understand better the osteoinductivity of these graft materials. The rat heterotopic model has been used successfully to show the sequence of events involved in the endochondral ossification process resulting in osteoinduction. In this study, the osteoinductive potential of human demineralized bone powder was assessed, using immune compromised rats (athymic rnu/rnu) to avoid problems associated with cross species incompatibilities. Implants were placed in subcutaneous or intermuscular sites. This model is characterized to provide a basis for routinely determining the performance of human demineralized bone powder. Demineralized bone powder was prepared from rat and human cortical bone according to a strict protocol. The lack of response to guanidine HCl extracted (noninductive) demineralized bone showed the selectivity of the assay. The same lots of human and rat demineralized bone were tested in sequential experiments during a 1-year period. These results showed reproducible induction of the demineralized bone powder between experiments. Combining demineralized bone with the guanidine HCl extracted demineralized bone in varying ratios tested the sensitivity of the assay. These results showed an increase in bone formation with increasing quantities of active demineralized bone and established the ability of the bioassay to differentiate between the various levels of active (osteoinductive) demineralized bone powder. With this model, consistent performance of demineralized bone powder processed by well controlled methods was seen.

Animals↗
PubMed1997

Mechanical and morphologic investigation of the tensile strength of a bone-hydroxyapatite interface.

For load-bearing calcium-phosphate biomaterials, it is important to understand the relative contributions of direct physical-chemical bonding vs. mechanical interlocking to interfacial strength. In the limit of a perfectly smooth hydroxyapatite (HA) surface, a tensile test of the bone-HA interface affords an opportunity to isolate the bonding contribution related to HA surface chemistry alone. This study measured the bone-HA interfacial tensile strength for highly polished (approximately 0.05 micron alumina) dense HA disks (5.25 mm in diameter, 1.3 in mm thickness) in rabbit tibiae. Each of five rabbits received four HA disks, two per proximal tibia. Pull-off loads ranged from 3.14 +/- 2.38N at 55 days after implantation to 18.35 +/- 11.9N at 88 days; nominal interfacial tensile strengths were 0.15 +/- 0.11 MPa and 0.85 +/- 0.55 MPa, respectively. SEM of failed interfaces revealed failures between HA and bone, within the HA itself and within adjacent bone. Tissue remnants on HA were identified as mineralized bone with either a lamellar or trabecular structure. Oriented collagen fibers in the bone intricately interdigitated with the HA surface, which frequently showed breakdown at material grain boundaries and a rougher surface than originally implanted. Mechanical interlocking could not be eliminated as a mode of tissue attachment and contribution to bone-HA bonding, even after implanting an extremely smooth HA surface.

Alloys↗
PubMed1991

Cash budgeting: an underutilized resource management tool in not-for-profit health care entities.

Cash budgeting is generally considered to be an important part of resource management in all businesses. However, respondents to a survey of not-for-profit health care entities revealed that some 40 percent of the participants do not currently prepare cash budgets. Where budgeting occurred, the cash forecasts covered various time frames, and distribution of the document was inconsistent. Most budgets presented cash receipts and disbursements according to operating, investing, and financing activities--a format consistent with the year-end cash flow statement. By routinely preparing monthly cash budgets, the not-for-profit health care entity can project cash inflow/outflow or position with anticipated cash insufficiencies and surpluses. The budget should be compared each month to actual results to evaluate performance. The magnitude and timing of cash flows is much too critical to be left to chance.

Budgets↗
PubMed1976

Comparison of effects of prolactin and growth hormone on adrenal 5alpha-reductase in hypophysectomized rats.

Adrenal 5alpha-reductase activity was measured in female rats 0, 2, 5, and 6 days after hypophysectomy. Enzyme activity increased progressively exhibing a 35-fold elevation at 6 days. The effects of high (250 mug/100 g of body wt), intermediate (25 mug/100 g of body wt), and low (2.5 mug/100 of body wt) daily doses of bovine prolactin and bovine growth hormone were compared at 2 and 5 days posthypophysectomy. At 2 days, enzyme activity was partially inhibited by the high and intermediate doses of prolactin and not affected by growth hormone. At 5 days all doses of prolactin were inhibitory, whereas enzyme activity was suppressed only by the high dose of growth hormone. With a given dose of hormone, the amount of suppression of enzyme activity is greater at 5 days than at 2 days posthypophysectomy. In 5-day hypophysectomized rats the inhibitory effects of prolactin and growth hormone were additive. It is concluded that: (i) hormonal sensitivity and responsiveness of the adrenal reductase pathway increases with duration of pituitary ablation; (ii) the reductive pathway is more sensitive to the effects of prolactin than growth hormone; and (iii) the effects of growth hormone and prolactin on reductase activity are mediated via different mechanisms, as suggested by the additive effects of individual hormones.

Adrenal Glands↗