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Biomedical subjects

R Miller

Publications and source records attributed to R Miller.

At least 451 records · Page 25Linked to original sources
PubMed1993

Pressure events surrounding oesophageal acid reflux episodes and acid clearance in ambulant healthy volunteers.

Previous studies of the mechanisms that precipitate acid reflux episodes and acid clearance have used unphysiological, short term hospital based data. A new 24 hour pH and motility recording system combined with computerised data analysis have been used to study naturally occurring acid reflux episodes in healthy ambulant volunteers. A variety of events that produced recognisable transdiaphragmatic pressure patterns were associated with acid reflux episodes (particularly belching). Peristaltic waves were the predominant contractions leading to oesophageal acid clearance and were the commonest contraction type during reflux episodes. Peristaltic wave parameters (amplitude, velocity, frequency, and percentage proportion) varied during different periods of the 24 hour recording. This study has produced new information about 24 hour oesophageal function and naturally occurring acid reflux which will provide a basis for comparison with patients with gastro-oesophageal reflux disease.

Adolescent↗
PubMed1993

Patterns of hospital care for patients with HIV infection and AIDS.

OBJECTIVE: The aims were to describe the use of inpatient resources by patients with HIV infection and patients with AIDS; to examine trends in service use over time; and to provide data for planners concerned with service provision for HIV infection. SETTING: An inner London health district reporting 9% of AIDS cases nationally. DESIGN: Data on survival times and inpatient and day care use of resources were derived from existing patient records or collected prospectively between 1983 (when the first case of AIDS was diagnosed in the district) and 31 March 1990. SUBJECTS: A total of 488 HIV positive patients of whom 396 had been diagnosed as having AIDS were studied. MEASUREMENTS AND MAIN RESULTS: Inpatient days consumed per annum; trends in the number of bed days per person year with AIDS; the lifetime inpatient use per AIDS patient; and the influence of survival on service use estimates were determined. Altogether 16.4% of a total 17,785 hospital inpatient days were attributable to HIV positive patients who did not fulfil the criteria for AIDS. For patients with AIDS, there was an initial increase in the intensity of inpatient use in 1987 when a dedicated HIV ward was opened. After 1988, however, inpatient use fell to 30.8 bed days per person year with AIDS. Patients diagnosed after April 1987 had noticeably longer survival times than those diagnosed earlier (a median of 17-18 months compared with a median of 10-11 months). From 214 lifetime service use records, it was estimated that patients with short survival (less than six months) would consume 36 days of inpatient care, while those expected to survive longer would consume approximately twice that number of days, irrespective of how much longer they survived. CONCLUSIONS: The data indicate less intensive use of inpatient care by AIDS patients over time, and hence the apparent ability to manage an increasing AIDS patient workload without a comparable increase in occupied bed days. Increases in the size of that workload and changes in the survival profile of patients, together with a relatively constant rate of service demand by longer survivors, however, will continue to place increasing strains on finite inpatient resources. Further research is needed to establish the extent to which the greater use of outpatient and community services can offset this.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Notes: a suitable case for audit.

The increasing emphasis on management responsibilities and audit led us to investigate the state of surgical notes in our hospital. Twelve criteria were evaluated regarding information that should be contained in the notes and the absence of this important information was documented. Deficiencies were revealed in all criteria selected. Until hospital patients files are well kept and maintained, retrospective audit whether financial or medical will not be valid. A significant injection of resources is required to redress the situation. Hospitals which have not carried out detailed studies into the contents of their notes need to do so as a matter of urgency.

Humans↗
PubMed1993

A tissue equivalent phantom for stereotactic radiosurgery localization and dose verification.

A tissue equivalent head phantom was utilized in the stereotactic localization and dose verification of radiosurgery procedures with the Leksell Gamma Knife Unit at the University of Kentucky Medical Center. A radiation dose-dependent color-doped gel target was positioned within the head phantom and stereotactically localized using either angiography, CT, or MR techniques. Utilizing standard Gamma Knife treatment procedures, the head phantom was irradiated, which resulted in a color change of the gel tumor at the position of the treatment isocenter and thereby confirmed the localization procedure. Additionally, a radiation dosimeter (thermoluminescent dosimetry--TLD) was positioned within the head phantom and localized using an angiography frame and a standard radiation therapy simulator. The phantom skull measurements and the dosimeter coordinates were entered into the Leksell Gamma Knife dose planning computer (KULA) and an irradiation time for 40 Gy using the 18-mm collimator was determined. The TLD dose evaluations were relatively determined using a cobalt-60 calibration curve. The experimental dose verification results agreed well (+/- 4%) with computer dose estimates.

Algorithms↗
PubMed1993

Intrinsic and extrinsic carpal ligaments: evaluation by three-dimensional Fourier transform MR imaging.

OBJECTIVE: As evaluation of the anatomic and functional integrity of intrinsic and extrinsic carpal ligaments with conventional imaging methods is difficult, we designed a study to evaluate the ability of three-dimensional Fourier transform MR imaging to show the carpal ligaments. SUBJECTS AND METHODS: We obtained coronal MR images of 15 cadaveric wrists and 15 wrists of patients, using three-dimensional volume acquisition with a gradient-recalled echo sequence and a 1.5-T magnet. The MR findings were compared with the findings on dissection in the 15 cadaveric wrists and with the surgical findings in eight patients. RESULTS: All the volar ligaments had a striated appearance on MR images, with alternating bands of low and intermediate signal intensity. No tears of the extrinsic ligaments were seen. The intrinsic scapholunate and lunotriquetral ligaments were seen as structures with more homogeneously intermediate intensity attaching to their adjacent bone through high-signal-intensity hyaline cartilage. For the cadaveric wrists, MR indications of a tear of the scapholunate ligament were true-positive in three and false-negative in three; indications of a tear of the lunotriquetral ligament were true-positive in five, false-positive in two, and false-negative in one. For the eight patients with surgical confirmation, the MR findings regarding tears were true-positive in two and true-negative in six. Neither surgery nor MR imaging showed any tears of the scapholunate ligament. CONCLUSION: Three-dimensional Fourier transform MR imaging with thin slices provides the resolution necessary to visualize the anatomic detail of the extrinsic and intrinsic ligaments of the wrist, but additional clinical experience with this technique will be required to determine its diagnostic capabilities.

Carpal Bones↗
PubMed1993

Intracerebral hemorrhage more than twice as common as subarachnoid hemorrhage.

The authors report a study of all instances of spontaneous intracerebral hemorrhage (ICH) (188 cases) and subarachnoid hemorrhage (SAH) (80 cases) that occurred in the Greater Cincinnati area during 1988. Adjusted for age, sex, and race, the annual incidence of ICH was 15 per 100,000 population (95% confidence interval 13 to 17) versus six per 100,000 for SAH (95% confidence interval 5 to 8). The incidence of ICH was at least double that of SAH for women, men, and whites and approximately 1 1/2 times that for blacks. The 30-day mortality rate of 44% for ICH was not significantly different from the 46% mortality rate for SAH. Despite the evidence that ICH is more than twice as common and the disorder just as deadly as SAH, clinical and laboratory research continues to focus primarily on SAH.

Adolescent↗
PubMed1993

Safe, compact and portable system for regional chemotherapeutic hyperthermic perfusion procedures.

Perfusion techniques utilizing hyperthermic chemotherapy have been established as a successful modality of therapy for isolated metastatic malignant melanoma. The combination of chemotherapeutic agents (Dactinomycin, thiotepa and Mechlorethamine HCl) given in high doses, not possible systemically, combined with hyperthermia (40-42 degrees C) in an isolated extremity has shown greater tumor regression compared with systemic medication only. Many of the isolated limb perfusion procedures are performed in non-cardiac centers, especially at specialized cancer institutions. This often presents new obstacles for the perfusionist including lack of adequate perfusion equipment and disposables. Other obstacles include unfamiliarity of the operating room staff with the heart-lung machine and inappropriate and/or unsafe handling of the perfusion circuit. In order to overcome these obstacles and enhance safety, portability and effectiveness, the authors have developed an isolated limb perfusion system. The purpose of this study was to compare the parameters of treatment and long term outcomes demonstrated by our system and method, to previously published data. The qualitative comparative analysis was performed between eight treatments with this type of perfusion system and outcome data previously published. It is the authors' conclusion that the portable isolated limb perfusion system achieved all of the required parameters to provide safe and effective treatment for this type of melanoma. No demonstrated variation of the long term clinical results in our patient population was seen when compared to previously published data.

Adult↗
PubMed1993

Follow-up after patch aortoplasty for coarctation of aorta.

BACKGROUND: Patch aortoplasty (PA) for coarctation of aorta (COA) can lead to aneurysm formation at the repair site. X-ray, echocardiogram and computed tomography are unreliable for diagnosis of this complication. OBJECTIVE: To evaluate prospectively patients with PA for COA by magnetic resonance imaging (MRI) to detect presence of aneurysm at the repair site. DESIGN: All patients who underwent PA at the authors' institution were identified. MRI was performed in transverse and long axis oblique views on all patients except those who had, or were going to have, aortic angiography for other reasons. Details of the surgical procedure were obtained from the hospital records. RESULTS: Of the 18 patients studied, 15 had MRI and three had aortic angiography. Age at PA ranged from one week to 13.3 years (mean 6.3 years). The interval from PA to MRI or angiography was 9.5 years (range four to 12.5). No aneurysm was detected in any patient. Recoarctation was diagnosed in two patients not previously suspected but discovered on MRI. At PA the intimal shelf causing coarctation was either not excised or only minimally trimmed in 14 of 15 instances. CONCLUSIONS: The incidence of late aneurysm formation following PA for COA is low in the authors' patients, possibly due to minimal intimal damage at repair, although these patients should be followed longer. MRI was useful for assessment of aneurysm and restenosis.

Adolescent↗
PubMed1993

Medial unicompartmental arthroplasty. A survival study of the Oxford meniscal knee.

One hundred twenty-one knees with medial compartment osteoarthrosis were treated by unicompartmental arthroplasty with the Oxford Knee. The strict selection criteria were (1) the presence of a functioning anterior cruciate ligament, (2) fully correctable deformity, and (3) full thickness of articular cartilage in the lateral compartment. The mean elapsed time from surgery was 44.4 months. One knee has required revision for a loose tibial component. The results at this stage are as acceptable as those of tricompartmental knee arthroplasty and better than those of high tibial osteotomy.

Aged↗
PubMed1993

Cardiac pathology in patients with end-stage renal disease maintained on hemodialysis.

We report the spectrum of cardiovascular pathology found on autopsy examination in 106 consecutive patients with end-stage renal disease. Cardiovascular pathology was present in nearly all patients, and was the most frequent cause of death (36%), with acute myocardial infarction accounting for 15%. Particularly frequent pathologic findings were left ventricular hypertrophy, coronary and aortic atherosclerosis, pericarditis with effusion, myocardial fibrosis, and valvular dilatation. Cardiovascular death rate was higher during the first year than after the fifth year of dialysis. Nearly all patients had a history of hypertension. The nature of the underlying cause of renal failure and pre-existing cardiovascular disease, specifically diabetes mellitus and hypertension, were the principal predictors of cardiovascular mortality rather than maintenance hemodialysis therapy per se.

Adult↗
PubMed1992

Use of nonsteroidal anti-inflammatory drugs in food animal practice.

We attempted to determine the extent to which nonsteroidal anti-inflammatory drugs (NSAID) are used in the treatment of food animals, and whether withdrawal times for milk and slaughter are recommended to clients. A survey questionnaire was mailed to a stratified random sample of 2,000 veterinarians whose practices were at least half food animals. A cross-sectional study was used to examine the responses to determine whether differences existed on the basis of a respondent's geographic location, number of years since graduation from veterinary college, and percentage of practice devoted to beef and dairy cattle. The response rate was 71% (1,424/2,000). Of those practitioners responding, 93% (1,325/1,424) reported using NSAID, with approximately 57 (751/1,322), 24 (327/1,322), and 18% (244/1,322) of respondents reporting use more than once a week, once a week, and 1 to 2 times per month, respectively. Dairy practitioners reported more frequent use than did beef practitioners. Use of flunixin meglumine was reported more frequently than the use of aspirin, phenylbutazone, or dipyrone. Approximately 88% (1,146/1,306) of respondents that used NSAID did so in combination with antibiotics. Withdrawal times for milk and meat were made on the basis of guidelines for the antibiotic. When using NSAID alone, recommendations for withdrawal times for milk and meat varied extensively. Overall, practitioners indicated that NSAID were useful and necessary for the treatment of food-producing animals.

Animals↗
PubMed1992

High-performance liquid chromatographic assay for 1-aminocyclopropanecarboxylic acid from plasma and brain.

A reversed-phase high-performance liquid chromatographic method for the analysis of 1-aminocyclopropanecarboxylic acid (ACPC) from plasma or brain tissue is described. Samples were deproteinized with perchloric acid, centrifuged, alkalinized with potassium hydroxide and recentrifuged. The supernatants were derivatized with o-phthaldialdehyde and injected onto a C18 3-microns column (100 mm x 4 mm I.D.) pumped with 1 ml/min methanol-acetonitrile-0.1 M sodium phosphate buffer pH 6.0 (28:5:67, v/v). The retention times for ACPC and the internal standard were 15 and 31 min, respectively. The minimum detectable amount of ACPC was 0.08 nmol. The extraction recovery of ACPC (2.7-270 nmol) from spiked plasma or brain tissue ranged from 88 to 109%. The intra- and inter-day coefficients of variation for 27 nmol ACPC were 3.9 and 4.9%, respectively. This method was utilized to obtain preliminary pharmacokinetic parameters following ACPC administration to mice.

Amino Acids↗
PubMed1992

Description and evaluation of the influence of veterinary presence on the use of antibiotics and sulfonamides in dairy herds.

A longitudinal study was conducted over 2 years to identify types of antibiotics and sulfonamides used in Michigan dairy herds for disease prevention and treatment, to determine patterns of use of antibiotics and sulfonamides by herd size and animal age group, and to determine the influence of veterinary presence during diagnosis on the types of antimicrobials used for disease treatments. In order of frequency, the most commonly used preventive antibiotic and sulfonamides were penicillins, tetracyclines, aminoglycosides, and cephalosporins, making up over 86% of all antimicrobials used for disease prevention. The most commonly used therapeutic antibiotics and sulfonamides were penicillins, tetracyclines, aminoglycosides, and sulfonamides, making up over 81% of all antimicrobial drugs used for disease treatment. Cows received the greatest number of drugs, followed by calves (cattle from birth to weaning). Young stock (cattle from weaning to first calving) received the lowest number of drugs. All herds had similar patterns of drug use for the 3 age groups, regardless of herd size. With the exception of polymyxin and chloramphenicol, producers used antibiotics on their own more than with a veterinarian present or on the advice of a veterinarian. Overall, veterinary presence was significantly associated with increased use of tetracyclines, sulfonamides, and nitrofurans, and decreased use of penicillins and aminoglycosides. Implications for drug residue prevention strategies are discussed, with emphasis on the role of the practicing veterinarian.

Animals↗