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Biomedical subjects

D A Gilbert

Publications and source records attributed to D A Gilbert.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Evaluating evaluation: assessment of the American Board of Internal Medicine Resident Evaluation Form.

The American Board of Internal Medicine suggests use of a standard form to rate residents on nine dimensions (such as clinical judgment and overall clinical competence) on a scale of 1 to 9. The authors examined the psychometric evidence for reliability and validity of 1,039 ratings of 85 residents by 135 attendings in a single internal medicine residency program. Of these ratings, 95.6% were from 6 to 9. Factor analysis revealed that high correlations among the nine dimensions (r ranged from 0.72 to 0.92) resulted from a single global factor accounting for 86% of the variance. The study also examined whether the form reliably distinguishes among residents scoring between 6 and 9. Agreement among attendings rating the same individual was weak (average reliability = 0.64, by the method of James). The rating method fails to discriminate dimensions of clinical care and has low reliability for distinguishing among competent residents.

Clinical Competence↗
PubMedDate not supplied

An endoscopic Doppler probe for assessing intestinal vasculature.

Flexible fiberoptic endoscopes permit the physician to inspect the mucosal surface of the upper gastrointestinal tract and colon. However, this visual inspection provides little information about the underlying vascular supply to the intestinal wall. We tested the hypothesis that a Doppler probe could be constructed small enough to pass through the biopsy channel of a fiber endoscope and be used with it while performing endoscopy. The purpose would be to determine the location of patent arteries or veins, determine the magnitude and waveforms of the velocity in them, and estimate their contribution or potential contribution to intestinal bleeding. For this purpose, a miniature catheter probe (1.8 mm O.D. and 2 m in length) and an electronic range limited pulsed Doppler unit were developed. This probe and unit were studied in a series of 13 dogs to determine efficacy of detecting arterial and venous flow and to test the safety of the device. The duodenum was surgically exposed and opened in the region of the common bile duct (CBD). Arteries and veins surrounding the CBD were studied. Particular attention was directed to arterial structures which clinically pose a risk of bleeding when performing endoscopic papillotomy, a therapeutic technique in which the papilla of Vater is cut to release bile duct stones. The results of the study revealed that the probe could indeed detect arterial and venous structures accurately. There was no evidence that the probe produced any injury to the common bile duct or pancreas by histological or serum amylase studies and the device was determined safe and suitable for clinical evaluation.

Animals↗
PubMedDate not supplied

An endoscopic Doppler probe: preliminary clinical evaluation.

A new pulsed Doppler catheter has been developed for use during gastrointestinal fiberendoscopy. Modern gastrointestinal endoscopy allows inspection of the wall of the entire esophagus, stomach, duodenum, and colon. Diagnosis is performed by inspecting the surface of the mucosa, biopsy, and cytology. However, it is not possible to determine the characteristics of the blood vessels of the wall beneath the mucosa with available techniques. We have developed a Doppler system which is miniature and can be passed down the biopsy channel of standard fiberendoscopes. This 8 MHz device incorporates range limiting to select the depth of interrogation by Doppler. The length of the probe is 2 m, and the diameter is 1.8 mm. This device has been tested in animal studies for efficacy and safety and is now being tested clinically in patients. The probe has been tested for two indications: the detection of the retroduodenal artery prior to endoscopic papillotomy for retained bile duct stones (90 patients); and the detection of flow in esophageal varices before and after endoscopic sclerotherapy (33 patients). Preliminary results are encouraging and suggest that this device can give information about submucosal blood vessels which cannot be detected using other methods.

Ampulla of Vater↗
PubMedDate not supplied

Analytical DNA fingerprinting in lions: parentage, genetic diversity, and kinship.

The application of hypervariable minisatellite genomic families to the reconstruction of population genetic structure holds great promise in describing the demographic history and future prospects of free-ranging populations. This potential has not yet been realized due to unforeseen empirical constraints associated with the use of heterologous species probes, to theoretical limitations on the power of the procedure to track genic heterozygosity and kinship, and to the absence of extensive field studies to test genetic predictions. We combine here the technical development of feline-specific VNTR (variable number tandem repeat) families of genetic loci with the long-term demographic and behavioral observations of lion populations of the Serengeti ecosystem in East Africa. Minisatellite variation was used to quantify the extent of genetic variation in several populations that differed in their natural history and levels of inbreeding. Definitive parentage, both maternal and paternal, was assessed for 78 cubs born in 11 lion prides, permitting the assessment of precise genealogical relationships among some 200 lions. The extent of DNA restriction fragment sharing between lions was empirically calibrated with the coefficient of relatedness, r, in two different populations that had distinct demographic histories. The results suggest that reliable estimates of relative genetic diversity, of parentage, and of individual relatedness can be achieved in free-ranging populations, provided the minisatellite family is calibrated in established pedigrees for the species.

Animals↗
PubMedDate not supplied

Population characteristics of DNA fingerprints in humpback whales (Megaptera novaeangliae).

Humpback whales exhibit a remarkable social organization that is characterized by seasonal long-distance migration (> 10,000 km/year) between summer feeding grounds in high latitudes and winter calving and breeding grounds in tropical or near-tropical waters. All populations are currently considered endangered as a result of intensive commercial exploitation during the last 200 years. Using three hypervariable minisatellite DNA probes (33.15, 3'HVR, and M13) originally developed for studies of human genetic variation, we examined genetic variation within and among three regional subpopulations of humpback whales from the North Pacific and one from the North Atlantic oceans. Analysis of DNA extracted from skin tissues collected by biopsy darting from free-ranging whales revealed considerable variation in each subpopulation. The extent of this variation argues against a recent history of inbreeding among humpback whales as a result of nineteenth- and twentieth-century hunting. A canonical variate analysis suggested a relationship between scaled genetic distance, based on similarities of DNA fingerprints, and geographic distance (i.e., longitude of regional subpopulation). Significant categorical differences were found between the two oceanic populations using a multivariate analysis of variance (MANOVA) with a modification of the Mantel nonparametric permutation test. The relationship between DNA fingerprint similarities and geographic distance suggests that nuclear gene flow between regional subpopulations within the North Pacific is restricted by relatively low rates of migratory interchange between breeding grounds or assortative mating on common wintering grounds.

Animals↗
PubMedDate not supplied

Status evaluation: endoscopic ultrasonography. American Society for Gastroenterology Endoscopy. Technology Assessment Committee.

Endoscopic ultrasound is a new technology that improves the local staging of esophageal, gastric, and rectal carcinomas. In addition, EUS may provide useful information which will affect management in individual patients with subepithelial masses (e.g., varices, leiomyomas) and pancreatic diseases. Other imaging studies such as transcutaneous ultrasonography and CT are still necessary to detect distant metastatic disease. At present, EUS may be best reserved for use by individuals who have sufficient patient materials to provide broad experience with the technique. Physicians at centers where large numbers of patients with gastrointestinal cancer are evaluated may find this technology most useful. Even in patients with malignancy, however, studies are needed to show that the improved local staging by EUS will translate into changes in patient management and improved outcome.

Digestive System↗
PubMedDate not supplied

Status evaluation: biliary stents. American Society for Gastrointestinal Endoscopy. Technology Assessment Committee.

Large caliber plastic stents (10 to 11.5 French) have become widely accepted as an alternative to surgery in the treatment of many malignant and benign lesions of the biliary tract. Procedure-related early complications occur at an acceptable rate (8 to 10%) and procedure-related mortality is approximately 2%. Late clogging occurs at a mean of 4 to 6 months. This results in the need to change a clogged stent in 20 to 35% of surviving patients with malignant disease. In benign or malignant disease, when long-term stenting is desired, it is generally recommended to prophylactically replace the stent every 4 to 6 months to avoid clogging. While several mechanisms of clogging have been elucidated, research studies have failed to lead to a clinically available improvement in duration of patency. The role of expandable metal stents in the treatment of malignant and benign biliary strictures has not been established. Despite their large internal diameter, they may be associated with late problems related to stent clogging from tumor ingrowth or overgrowth. Technical difficulties and expense, as well as lack of data from prospective randomized trials, limit current recommendation for their use at this time.

Bile Ducts↗
PubMedDate not supplied

Status evaluation: hot biopsy forceps. American Society for Gastrointestinal Endoscopy. Technology Assessment Committee.

Monopolar hot biopsy forceps were developed for simultaneous tissue biopsy and electrocoagulation. Many endoscopists used these forceps for coagulation of diminutive polyps of the colon. The rationale for diminutive polyp eradication is to destroy neoplastic tissue and possibly prevent colon cancer. However, convincing data to document a reduction in the incidence of colorectal cancer or even complete obliteration of all treated diminutive polyps with hot biopsy forceps are lacking. Complications of hot biopsy include hemorrhage, perforation, and post-coagulation syndrome. Tissue injury is deeper with monopolar hot biopsy forceps than bipolar forceps. The right colon is particularly susceptible to transmural injury and perforation. For small polyp obliteration, comparative studies of hot biopsy (monopolar and bipolar) with other techniques such as cold biopsy combined with thermal probes, large cup cold biopsy removal, and snare electrocoagulation are warranted. The necessity to biopsy typical appearing angiomata does not seem warranted on a routine clinical basis. The expected obliteration rates of small angiomata or rates of controlling lower gastrointestinal bleeding from colon angiomata after monopolar hot biopsy electrocoagulation have not been well documented. Heater probe or bipolar electrocoagulation have been safely and effectively applied to bleeding colon angiomata. These newer coagulation probes are recommended as an alternative to hot biopsy forceps for treatment of bleeding colonic angiomata.

Biopsy↗
PubMedDate not supplied

Status evaluation: sphincter of Oddi manometry. American Society for Gastrointestinal Endoscopy. Technology Assessment Committee.

SO manometry appears to be helpful in defining a group of patients with biliary pain or idiopathic recurrent pancreatitis who may benefit from endoscopic or surgical treatment. It is a procedure that requires considerable time and endoscopic expertise along with knowledge of the manometric interpretation of sphincter of Oddi dysfunction. The diagnostic accuracy of SO manometry and criteria for basing therapeutic decisions on manometric findings need further study and verification.

Biliary Tract Diseases↗
PubMedDate not supplied

Effectiveness of computer assisted instruction and small-group review in teaching clinical calculation.

This study compared the effectiveness of computer assisted instruction (CAI) and small-group review in teaching clinical calculation to associate degree nursing (ADN) students. Subjects were 123 ADN students randomly assigned to receive 50 minutes of supplemental instruction in clinical calculation by means of CAI or small-group review. Both CAI and small-group review were based on Gagné's events of instruction. An analysis of covariance of the scores on a 20-item exam, developed by five expert faculty members and having a Kuder-Richardson Formula 20 (KR-20) of 0.74, revealed no significant difference in performance between groups. The authors concluded that, when teaching strategies are comparable, CAI is as effective as small group review among ADN students for supplemental instruction in clinical calculation.

Adult↗