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Biomedical subjects

D C Taylor

Publications and source records attributed to D C Taylor.

At least 73 records · Page 4Linked to original sources
PubMed1996

Papillary urothelial hyperplasia. A precursor to papillary neoplasms.

Precursor lesions of papillary urothelial neoplasms have not been well characterized. We reviewed the surgical pathology files of the Johns Hopkins Hospital and three regional hospitals from 1992 to present. Sixteen cases of papillary hyperplasia, defined as undulating urothelium arranged into thin mucosal papillary folds, were identified (in 11 men and five women: age range, 40-89 years). Relative to the diagnosis of papillary hyperplasia, nine patients had a history of papillary urothelial neoplasms; in one of these cases, the patient also had subsequent papillary urothelial neoplasms, and two of these patients had concurrent papillary urothelial neoplasms with papillary hyperplasia. In one of these nine cases, papillary hyperplasia arose in the scar of a prior papillary urothelial neoplasm. In two cases, the patients had concurrent, yet no prior history, of papillary urothelial neoplasms. Of these 11 cases, three had multiple resections showing papillary hyperplasia over time. In case 12, the patient had a history of moderate urothelial atypia. The remaining four patients had no history of papillary urothelial neoplasms or urothelial atypia. We describe papillary hyperplasia as a well-defined entity that is usually asymptomatic and generally found on routine follow-up cystoscopy for papillary urothelial neoplasms. Papillary hyperplasia appears to be a precursor lesion of low-grade papillary urothelial neoplasms.

Adult↗
PubMed1996

Somatization and the vocabulary of everyday bodily experiences and concerns: a community study of adolescents.

OBJECTIVE: To describe the frequency of everyday bodily experiences and health concerns in a general population of adolescents 12 to 16 years of age in Ontario and to explore whether the concept of "somatization," identified from those youths with many of these symptoms, is meaningful and related to other variables. METHOD: A representative sample of the population was obtained by stratified random sampling. Children with a chronic medical condition were excluded. Parents and their adolescent children filled out a series of questionnaires to measure health concerns, complaints, and more dramatic losses of function. Information was also collected on certain background factors, psychiatric problems, and impairments in adaptive functioning. RESULTS: Parents and youths endorsed the items with the same rank order of frequency, but there was virtually no agreement between parents and youths on the presence or absence of individual somatic symptoms. Users of medical services did not tend to have many more health concerns than others, and there was a weak relationship between the number of health concerns reported by a youth and both impairment in adaptive functioning and psychiatric problems. CONCLUSION: These data suggest that the concept of somatization has limited general value over and above a relationship with other psychiatric problems.

Adolescent↗
PubMed1996

Staff development of tutor skills for problem-based learning.

The medical faculty of the University of Liverpool is undergoing a major curriculum reform from a traditional course to a student-centred curriculum. To help facilitate the change, staff have been supported by a staff development programme. This paper describes the initial work-shop in a programme introducing problem-based learning for over 300 participants, and its evaluation.

Education, Medical, Undergraduate↗
PubMed1996

Follow-up of renal and mesenteric artery revascularization with duplex ultrasonography.

OBJECTIVE: To evaluate the long-term results of renal revascularization procedures using duplex ultrasonography: DESIGN: A case series. SETTING: A university-affiliated hospital. PATIENTS: Twenty-five patients who had undergone renal percutaneous transluminal angioplasty (PTA) (18 arteries), renal bypass (10 arteries) and mesenteric bypass (6 arteries). The mean follow-up was 22 months (range from 3 to 48 months) for those who underwent renal PTA, 23 months (range from 1.5 to 70 months) for those who underwent renal bypass and 34 months (range from 8 to 144 months) for those who underwent mesenteric bypass. MAIN OUTCOME MEASURES: Patency rates for the three procedures as assessed by duplex ultrasonography. RESULTS: Duplex ultrasonography demonstrated patency without stenosis after renal and mesenteric artery revascularization in 14 arteries subjected to renal PTA, 9 arteries subjected to renal bypass and 6 arteries subjected to mesenteric bypass. Three arteries that had renal PTA had recurrent vessel stenosis and one had occlusion. One artery that had renal bypass showed occlusion. CONCLUSIONS: Renal PTA, renal bypass and mesenteric bypass are durable procedures at 2 years of follow-up, and duplex ultrasonography is a valuable method for assessing the patency of arteries after renal and mesenteric revascularization.

Angioplasty, Balloon↗
PubMed1996

Parachuting injuries: a medical analysis of an airborne operation.

The purpose of this paper is to discuss parachuting variables as they affect support and planning. The authors retrospectively analyzed an operation in which a Ranger battalion parachuted onto an airfield drop zone. Leaders weighed Rangers to estimate the soldiers' load. The advance team failed to adequately coordinate administrative medical assistance on the drop zone. Forty-one Rangers were injured and evacuated from the drop zone (8.6% of the jumpers). Variables in such operations include drop zone selection, equipment weight, drop altitude, wind speed, the wind-flight angle, drop height, and jumper density over the drop zone. Solutions include cargo drops and leaders' repeated emphasis on minimizing the soldiers' loads in accordance with mission accomplishment.

Aviation↗
PubMed1996

Arthroscopic stabilization of acute initial anterior shoulder dislocation: the West Point experience.

Arthroscopic stabilization for acute initial shoulder dislocation has been the subject of thorough investigation at West Point over the past decade in an attempt to improve on the natural history of shoulder instability in our young athletic population. From January 1986 to December 1995, 127 patients were treated for acute initial shoulder dislocation at the United States Military Academy. Of the 55 patients treated nonoperatively, 47 (85%) have had recurrence of instability. Seventy-two patients were treated operatively during three separate phases in the evolution of arthroscopic management at our institution. The initial phase (1986 to 1988) of operative treatment included either arthroscopic abrasion or staple repair. The low recurrence rate (2 of 9) was promising. In the operative technique for the second phase (1988 to 1991) transglenoid sutures were used. Of the 21 patients treated in this manner, 18 (86%) had no recurrent instability at last follow-up (average, 32 months). In the third phase (1991 to 1993), patients were treated with a bioabsorbable tack and interscalene anesthesia, and in the sitting position. Thus far, 39 of the latest 42 cadetathletes with acute initial anterior shoulder dislocations have had stabilization with this bioabsorbable cannulated fixation device. The average age was 19.5 years (range, 17 to 23 years). Follow-up averaged 22 months. There were no perioperative complications. Of these 39 patients, 35 (90%) have a stable shoulder and have returned to preinjury performance status. One of 2 patients with recurrent subluxation and 1 of 2 patients with a traumatic redislocation required an open Bankart repair. In young athletes known to have high recurrence rates with nonoperative treatment, acute arthroscopic stabilization appears to be an effective minimally invasive treatment option that favorably alters the natural history of shoulder instability.

Adolescent↗
PubMed1996

Treatment of comminuted subtrochanteric femoral fractures in a young population with a reconstruction nail.

The authors report their experience using the Russell-Taylor reconstruction intramedullary interlocking nail in five comminuted subtrochanteric fractures in young paratroopers. The retrospective case series presented demonstrates the usefulness of this device for a challenging problem. Follow-up averaged 22 months and clinical results were good in that all soldiers could return to parachuting. The authors discuss surgical techniques and review the literature. The authors recommend consideration of the reconstruction nail use for this clinical problem.

Adult↗
PubMed1995

The effects of N-methyl-D-aspartate (NMDA) and non-NMDA receptor agonists and antagonists on hypothalamic neurones in the anaesthetized rat which respond to changes in scrotal skin temperature.

There are neurones in the pre-optic anterior hypothalamus of the anaesthetised rat which respond to changes in scrotal skin temperature. Neuronal firing rate can be increased by raising the scrotal skin temperature above 36 degrees C, and also by ionophoretic application of either N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) (a non-NMDA receptor agonist). The increase in neuronal firing evoked by thermal stimulation was prevented or diminished by concurrent application of either D-2-amino-5-phosphonopentanoic acid (D-AP5) (an NMDA receptor antagonist) or 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (a non-NMDA receptor antagonist) at doses which were sufficient to abolish or significantly diminish the effect of the specific agonist. It is probable that both NMDA and non-NMDA receptors are involved in the scrotal thermoafferent pathway in the rat.

Afferent Pathways↗
PubMed1995

Influence of surface coverage with poly(ethylene oxide) on attachment of sterically stabilized microspheres to rat Kupffer cells in vitro.

The attachment to rat Kupffer cells of polymeric microspheres, sterically stabilized with different amounts of pendant poly(ethylene oxide) (PEO), was assessed in vitro. Four types of copolymer polystyrene (PS) microspheres were synthesized by variation of four possible monomer ratios that included styrene, methoxy-PEO-methacrylate (750 and 2000 mol. wt PEO) and allylurea. This produced poly(styrene-(methoxy-PEO)methacrylate) microspheres with hydrophilic side-groups of either urea (PS-U-PEO) and/or mixed molecular weight (750/2000 mol. wt) PEO (PS-U-M-PEO, PS-M-PEO), or single molecular weight (2000) PEO (PS-PEO) at their surfaces. The hypothesis was tested that increasing the total content of PEO comprising the steric barrier reduces attachment to cell surfaces. Attachment of PEO microspheres bearing the urea spacer and/or mixed molecular weight PEO was found to be intermediate between charge stabilized control PS and PEO (2000 mol. wt) bearing particles. Post-adsorption of different Poloxamer (PEO-poly(propylene oxide)-PEO) surfactants to the microspheres further decreased attachment. Significant negative linear correlations between surface PEO content, measured by electron spectroscopy for chemical analysis (ESCA), and attachment to Kupffer cells were demonstrated. Decreases in attachment also resulted with all graft PEO particles bearing adsorbed sodium dodecyl sulphate (SDS), whilst the attachment of SDS-treated PS control particles increased. It is proposed that trains of adsorbed graft PEO are displaced by the SDS to increase the effective fraction of graft PEO within the steric layer. Overall, increasing the amount of hydrophilic PEO in the steric layer, from graft and adsorbed sources, reduces the attachment of these particles to Kupffer cells in vitro.

Analysis of Variance↗
PubMed1995

Arthroscopic bioabsorbable tack stabilization of initial anterior shoulder dislocations: a preliminary report.

Twenty-six consecutive cadet athletes sustained an acute, initial anterior shoulder dislocation. All dislocations required a manual reduction for initial treatment. Arthroscopy was performed within 10 days in all patients. The Beach chair position and interscalene anesthesia were used in each case. At arthroscopy, 25 patients had an avulsion of the anterior-inferior capsulolabral complex (Bankart lesion) from the glenoid rim. One patient had a lateral detachment of the inferior glenohumeral ligament from the humeral neck. Twenty-three patients had a Hill-Sachs lesion and 3 SLAP tears were noted. All Bankart lesions were repaired with a cannulated bioabsorbable fixation device. Nineteen patients, over 1 year postoperative, are the subject of this preliminary report. The average age was 19.5 years (range, 17 to 23 years). Follow-up averaged 19 months (range, 12 to 24 months). The average loss of external rotation was 3 degrees. There have been no recurrent dislocations and 1 patient has had a single episode of resubluxation. Using the Rowe point score, 16 patients were rated excellent, 2 good, and 1 fair. All of the athletes in this study have returned to preinjury performance status. Acute stabilization of initial anterior shoulder dislocations appears to be an effective treatment option in young athletes known to have high recurrence rates with nonoperative treatment. This particular technique has been safe with little morbidity.

Absorption↗
PubMed1995

Alteration of seed fatty acid composition by an ethyl methanesulfonate-induced mutation in Arabidopsis thaliana affecting diacylglycerol acyltransferase activity.

In characterizing the enzymes involved in the formation of very long-chain fatty acids (VLCFAs) in the Brassicaceae, we have generated a series of mutants of Arabidopsis thaliana that have reduced VLCFA content. Here we report the characterization of a seed lipid mutant, AS11, which, in comparison to wild type (WT), has reduced levels of 20:1 and 18:1 and accumulates 18:3 as the major fatty acid in triacylglycerols. Proportions of 18:2 remain similar to WT. Genetic analyses indicate that the fatty acid phenotype is caused by a semidominant mutation in a single nuclear gene, designated TAG1, located on chromosome 2. Biochemical analyses have shown that the AS11 phenotype is not due to a deficiency in the capacity to elongate 18:1 or to an increase in the relative delta 15 or delta 12 desaturase activities. Indeed, the ratio of desaturase/elongase activities measured in vitro is virtually identical in developing WT and AS11 seed homogenates. Rather, the fatty acid phenotype of AS11 is the result of reduced diacylglycerol acyltransferase activity throughout development, such that triacylglycerol biosynthesis is reduced. This leads to a reduction in 20:1 biosynthesis during seed development, leaving more 18:1 available for desaturation. Thus, we have demonstrated that changes to triacylglycerol biosynthesis can result in dramatic changes in fatty acid composition and, in particular, in the accumulation of VLCFAs in seed storage lipids.

Acyltransferases↗
PubMed1995

A possible role for lysozyme in determining acute exacerbation in chronic bronchitis.

The aggregation of non-serotypable Haemophilus influenzae (NTHI) by whole saliva from patients with chronic obstructive lung disease (COLD) was investigated. Significant differences were observed between salivary aggregating activity of a control and COLD population (P < 0.001). Saliva from patients less prone to acute exacerbations had a greater capacity to aggregate bacteria compared with saliva from patients with a predilection to infection. The mechanism of saliva-mediated aggregation of NTHI was investigated and shown to be related to lysozyme content. Lysozyme activity in saliva was measured by the turbidimetric technique and results showed that patients with chronic bronchitis had increased levels of salivary lysozyme, with a subpopulation within the non-infection-prone group having greater amounts. A significant difference was observed in salivary lysozyme between controls and non-infection-prone (P < 0.005) and infection-prone (P < 0.05) patients, respectively: the non-infection-prone patients having significantly (P < 0.005) more than the infection-prone patients. There was significant correlation (r = 0.742, P < 0.001) between salivary aggregation of NTHI and lysozyme activity. Chromatographically purified human lysozyme had a similar aggregation profile to that of saliva. There was no difference in serum and saliva lactoferrin concentrations between groups, but there was a significant increase (P < 0.05) in serum lysozyme concentration in the non-infection-prone group. This study suggests that the level of salivary lysozyme derived from macrophages may play an important role in determining resistance or susceptibility to acute bronchitis.

Acute Disease↗
PubMed1995

Fast-roping injuries among Army Rangers: a retrospective survey of an elite airborne battalion.

Fast-roping is a modified rappelling technique used by civilian and military special operations forces that frequently produces injuries. Highly classified until recently, fast-roping is poorly understood from a medical perspective. This paper presents a brief description of fast-roping and a retrospective survey of the types of fast-roping injuries sustained in a U.S. Army Ranger battalion. Injuries are similar to parachute landing fall injuries, but show a greater propensity for ankle injuries (30% of all injuries). The mechanisms of injury include landing injuries after a controlled descent and falls from a great height when an individual loses control of the rope.

Adolescent↗
PubMed1994

Estimation of sieving coefficients of convective absorption of drugs in perfused rat jejunum.

Intestinal absorption of many hydrophilic drugs cannot be explained solely in terms of pH-partition and solvent-drag effects have been described in a number of cases. However, quantitative estimates of sieving coefficient (phi) for drug molecules have tended to be variable. In the present work an in situ perfused intestinal loop preparation in the rat has been used to measure the disappearance of five hydrophilic drugs from the intestinal lumen and a mathematical model of drug absorption in the presence of net and unidirectional fluid fluxes has been developed. The model allows separate estimation of the convective (solvent drag) and nonconvective (partition) components of drug absorption from the experimental data. The five drugs studied were found to have phi values ranging from 0.1-0.9; this was highly dependent on molecular size. Analysis of the data shows that three of the drugs are absorbed almost exclusively by the convective process (caffeine, cimetidine, hydrochlorthiazide) while the other two are absorbed by both convective and nonconvective processes (salicylate, oxprenolol). We conclude that the methodology is a useful and reliable means of deriving separate estimates of these two components of drug absorption.

Animals↗
PubMed1994

Surface modification of poly(lactide-co-glycolide) nanospheres by biodegradable poly(lactide)-poly(ethylene glycol) copolymers.

The modification of surface properties of biodegradable poly(lactide-co- glycolide) (PLGA) and model polystyrene nanospheres by poly(lactide)-poly(ethylene glycol) (PLA:PEG) copolymers has been assessed using a range of in vitro characterization methods followed by in vivo studies of the nanospheres biodistribution after intravenous injection into rats. Coating polymers with PLA:PEG ratio of 2:5 and 3:4 (PEG chains of 5000 and 2000 Da. respectively) were studied. The results reveal the formation of a PLA:PEG coating layer on the particle surface resulting in an increase in the surface hydrophilicity and decrease in the surface charge of the nanospheres. The effects of addition of electrolyte and changes in pH on stability of the nanosphere dispersions confirm that uncoated particles are electrostatically stabilized, while in the presence of the copolymers, steric repulsions are responsible for the stability. The PLA:PEG coating also prevented albumin adsorption onto the colloid surface. The evidence that this effect was observed for the PLA:PEG 3:4 coated nanospheres may indicate that a poly(ethylene glycol) chain of 2000 Da can provide an effective repulsive barrier to albumin adsorption. The in vivo results reveal that coating of PLGA nanospheres with PLA:PEG copolymers can alter the biodistribution in comparison to uncoated PLGA nanospheres. Coating of the model polystyrene nanospheres with PLA:PEG copolymers resulted in an initial high circulation level, but after 3 hours the organ deposition data showed values similar to uncoated polystyrene spheres. The difference in the biological behaviour of coated PLGA and polystyrene nanospheres may suggest a different stability of the adsorbed layers on these two systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

An alteration in the host-parasite relationship in subjects with chronic bronchitis prone to recurrent episodes of acute bronchitis.

Acute episodes of bronchitis have been shown to be unequally distributed within a population of subjects with chronic bronchitis. Two groups were identified based on incidence of acute bronchitis--subjects who were 'infection-prone' (2-5 infections per year) and those who were 'non-infection-prone' (0-1 infections per year). Minor differences in clinical parameters existed, except for smoking experience. The non-infection-prone group included more current smokers, and the total smoking experience (in 'pack years') was significantly greater in this group. Between-year analysis demonstrated a stability of classification, established after a minimum of two years' prospective observation. Parameters of the host-parasite relationship were assessed in both groups. A significantly greater polybacterial colonization of the oropharynx was observed for chronic bronchitics, both infection-prone (P < 0.0001) and non-infection-prone (P < 0.001), compared with control subjects. Infection-prone chronic bronchitics had significantly greater total bacteria cultured from the oropharynx compared to the non-infection-prone group (P < 0.05); adherence of indigenous microflora to buccal epithelial cells, in particular Gram-positive cocci (P < 0.01) and in vitro adherence of non-serotypable Haemophilus influenzae to buccal cells (P < 0.05) compared with the control and non-infection-prone groups. These studies suggest that an important variation in subjects with chronic bronchitis is the binding capacity of epithelial cells for bacteria, which when increased enhances susceptibility to colonization and clinical infection.

Acute Disease↗