Search PubMed⌕ Search

Biomedical subjects

R W Smith

Publications and source records attributed to R W Smith.

At least 73 records · Page 4Linked to original sources
PubMed1995

A real-time electrical impedance tomography system for clinical use--design and preliminary results.

An instrument is described which produces images of the electrical impedance distribution within the body at a rate of 25 frames per second, allowing lung ventilation and lung perfusion to be observed in real time. The instrument makes impedance measurements using an array of 16 electrodes on the surface of the body, and reconstructs the images using a weighted backprojection technique. The design of the data acquisition electronics and the reconstruction and display processor are described. Some preliminary in vitro and in vivo results from the system are presented.

Algorithms↗
PubMed1995

Chrysiasis revisited: a clinical and pathological study.

Chrysiasis is a distinctive and permanent pigmentation of light-exposed skin resulting from the administration of parenteral gold salts. We report a study of 40 Caucasian patients with rheumatoid arthritis, treated with intramuscular sodium aurothiomalate, of whom 31 had chrysiasis. Visible changes develop above a threshold, equivalent to 20 mg/kg gold content, and their severity depends upon cumulative dose. Focal aggregates of particulate gold are deposited in the reticular and papillary dermis in amounts that correlate with the degree of pigmentation. Characteristically, initially the periorbital region is affected by a mauve discoloration, which intensifies and deepens into a blue/slate-grey colour, while extending to involve the face, neck and upper limbs. Although chrysiasis develops insidiously and patients may be unaware of the changes, positive identification is important in order to avoid misdiagnosis and medical mismanagement, and afford appropriate reassurance. Prevention is difficult, but measures to reduce sunlight exposure may be helpful.

Antirheumatic Agents↗
PubMed1995

Osteoarthritis of the hip joint and acetabular dysplasia in women.

OBJECTIVE: To investigate the suggestion that osteoarthritis (OA) of the hip joint is often caused by subclinical acetabular dysplasia among elderly British women. METHODS: We examined 393 hip joints from the radiographs of a sample of women aged 60-75 years undergoing intravenous urography. Acetabular dysplasia was assessed using measurements of the centre-edge (CE) angle and acetabular depth (AD), which are both reduced in this condition. OA was assessed using an overall grade based on the Kellgren and Lawrence system and by measurement of minimum joint space (MJS). RESULTS: MJS was the more repeatable measure of OA, and showed a strong correlation with overall grade (Spearman rank correlation coefficient rs = -0.61, p < 0.01). MJS was significantly negatively correlated with CE angle (Pearson correlation coefficient r = -0.25, p < 0.001) and AD (r = -0.11, p < 0.05). Consistent with these findings, there was a weak but significant positive correlation between overall grade of OA and one of the two measures (CE angle) of acetabular dysplasia. CONCLUSIONS: These results do not support the hypothesis that mild degrees of acetabular dysplasia account for a substantial proportion of hip OA in elderly women. Changes in hip joint geometry as a result of OA may be responsible for the weak negative association observed.

Aged↗
PubMed1995

Treatment of symptomatic hammertoe with a proximal interphalangeal joint arthrodesis.

This study examined 76 consecutive patients (100 feet) treated by a single surgeon for both flexible and rigid hammertoes with a PIP arthrodesis using custom-machined drills, a peg cutter, and hole cutter, combined with an extensor tenotomy and dorsal capsulotomy. Forty-eight percent of patients were defined as satisfied without reservation, 37% were defined as satisfied with reservations, and 15% were defined as dissatisfied. The incidence of radiographic fusion was 95% (130/137 toes). The most common reasons for either reservation or dissatisfaction included incomplete pain relief, residual toe angulation, and prolonged shoe wear restriction in the postoperative period. Based upon the results of this study, the authors suggest that when using a peg and socket arthrodesis for hammertoe correction (1) there is a 95% rate of radiographic fusion, (2) patients over 65 years old be alerted to a diminished rate of satisfaction, and (3) a distal flexor tenotomy be considered in patients with a preoperative DIP flexion contracture.

Adult↗
PubMed1994

Exposure to 60 Hz magnetic fields in the electric utility work environment.

Research that has attempted to examine the relationship between work exposures to magnetic fields and health effects has suffered from limited exposure information. Power-frequency electric and magnetic (EM) field exposures vary substantially between industries, occupations, and individuals. In this study magnetic field data were collected for a variety of occupational categories within an electric utility. The sampling procedures emphasized craft occupations that were presumed to have higher exposures to magnetic fields. The objectives were to provide better exposure information for an ongoing cancer mortality study, examine the relationship between different summary measures of magnetic field exposure, and make available descriptive information useful for exposure reduction and worker education. Principal components analysis (PCA) and Varimax rotation were used to explore the relationships between the different summary measures among all utility workers and among the subset of electrical craft occupations. Discriminant analysis was used to assess summary measures of exposure that differentiated occupational groups. Measurements for 770 days generated a total of 42378 hours of magnetic field data. Eleven summary indices of exposure were calculated for specific occupational groups. These include arithmetic mean, geometric mean, median, 95th and 99th percentiles, and fraction of measurements exceeding .5, 1, 5, 10, and 100 microT. Electrical craft occupations had higher work exposures than non-craft occupations. Electricians and substation operators had the highest exposures among craft occupations. We identified subsets of summary measures that were intercorrelated. The first PCA axis included the geometric mean, median, and the fractions exceeding 0.5 and 1.0 microT. This set of measures also were best at discriminating occupational groups. The relevance of these findings may become more important if consistent associations are found between particular occupations and disease and particular occupations and magnetic field summary measures. Further research is needed to evaluate these exposure assessment findings.

California↗
PubMed1994

Utilization of a time-limited holiday hotline by older adults.

Lonely older adults are frequently hesitant to reach out for help because they fear forced institutionalization or other loss of control over their lives. The utilization of a time-limited holiday hotline for outreach to lonely older persons is examined. There were 306 calls from aged persons. Grief and bereavement were the primary themes of these calls. Trained professionals and supervised students staffed the telephone bank and provided such services as responsive listening and community referrals.

Aged↗
PubMed1994

Abnormal microvascular responses in a lateral epicondylitis.

The laser Doppler flowmeter, an instrument highly sensitive to changes in blood flow velocity in the dermal microvascular bed, was used to examine a sympathetic vasomotor response (SVR) in 40 patients with lateral epicondylitis. There was a significant association between the absence of a normal SVR in the skin overlying the affected enthesis compared with the unaffected contralateral epicondyle (P < 0.01). These results suggest that local dysfunction of the sympathetic nervous system may be associated with the pathogenesis of anatomically discrete pain in the enthesopathy of epicondylitis.

Adult↗
PubMed1994

A prospective randomized trial comparing open versus laparoscopic appendectomy.

OBJECTIVE: The authors determined whether there was an advantage to laparoscopic appendectomy when compared with open appendectomy. SUMMARY/BACKGROUND DATA: The advantages of laparoscopic appendectomy versus open appendectomy were questioned because the recovery from open appendectomy is brief. METHODS: From January 15, 1992 through January 15, 1993, 75 patients older than 9 years were entered into a study randomizing the choice of operation to either the open or the laparoscopic technique. Statistical comparisons were performed using the Wilcoxon test. RESULTS: Thirty-seven patients were assigned to the open appendectomy group and 38 patients were assigned to the laparoscopic appendectomy group. Two patients were converted intraoperatively from laparoscopic appendectomies to open procedures. Thirty-one patients (81%) in the open group had acute appendicitis, as did 32 patients (84%) in the laparoscopic group. Mean duration of surgery was 65 minutes for open appendectomy and 87 minutes for laparoscopic appendectomy (p < 0.001). There were no statistically significant differences in length of hospitalization, interval until resumption of a regular diet, or morbidity. Duration of both parenteral and oral analgesic use favored laparoscopic appendectomy (2.0 days versus 1.2 days, and 8.0 days versus 5.4 days, p < 0.05). All patients were instructed to return to full activities by 2 weeks postoperatively. This occurred at an average of 25 days for the open appendectomy group versus 14 days for the laparoscopic appendectomy group (p < 0.001). CONCLUSIONS: Patients who underwent laparoscopic appendectomies have a shorter duration of analgesic use and return to full activities sooner postoperatively when compared with patients who underwent open appendectomies. The authors consider laparoscopic appendectomy to be the procedure of choice in patients with acute appendicitis.

Acute Disease↗
PubMed1994

Cerebellum and brainstem vasculopathy in systemic lupus erythematosus: two clinico-pathological cases.

The case histories are reported of two patients with systemic lupus erythematosus (SLE) who developed fatal neurological involvement, each presenting with cerebellar and brainstem signs. Neuro-pathological changes were confined to the cerebellum and brainstem, with clear evidence of a small vessel vasculopathy. The predominant histological abnormalities were multiple perivascular haemorrhages in one case and classical vasculitic changes in the other.

Adult↗
PubMed1994

Treatment of the atypical lesser toe deformity with basal hemiphalangectomy.

Eighty-six lesser toe basal hemiphalangectomies were performed in 52 patients. The surgical technique included an oblique dorsal incision, resection of 8 mm of bone, and an extensor tenotomy. Minimum follow-up was 2 years (range 2-6/1/2 years). Sixty percent of the patients had total relief of pain. Twenty-nine percent stated that they would not have the surgery again, and we categorized these patients as dissatisfied. An extensor tenotomy increased the satisfaction rate and was found to decrease the radiographic sagittal angulation of the toe. The preoperative diagnosis was significant to the outcome of the surgery. Patients with metatarsophalangeal joint synovitis and rheumatoid toe deformities had high rates of satisfaction; those with transverse deviation, metatarsalgia, and hammertoes with metatarsophalangeal joint subluxation/dislocation had lower rates of satisfaction. Seventy percent of the dissatisfied patients were dissatisfied because of persistent flexion deformity of the PIP joint or pain under the metatarsal head. We now add a PIP fusion if any flexion deformity, even a mild deformity, is present at the PIP joint and a plantar metatarsal condylectomy for metatarsalgia.

Adult↗
PubMed1994

Semantic memory and the granularity of semantic relations: evidence from speed-accuracy decomposition.

In the present study we examined whether semantic relations are atomistic unitary associations, or are complex concepts consisting of a number of relational elements. The complexity of the ownership relation was assessed by combining a relation verification task ("Many people own [cars/comets]") with the speed-accuracy decomposition procedure (Meyer, Irwin, Osman, & Kounios, 1988). The latter permits one to determine whether subjects achieve their final state of response accuracy in a single, discrete all-or-none transition, or whether the relevant processes yield partial information representing intermediate states of knowledge. The rationale was that the retrieval of a unitary relational link from a classical associative network should be an all-or-none affair. In contrast, a set of relational elements need not be processed as a unitary bundle, thereby allowing partial response-information states. In two experiments, we found evidence of such partial information (i.e., sensitivity in units of d'), lending support to the notion that relations are complex. Furthermore, the results suggest that the accumulation of guessing sensitivity was linear over time, weighing against alternate theoretical interpretations.

Humans↗
PubMed1993

Computerized three-dimensional reconstruction reveals cerebrovascular regulatory subregions in rat brain stem.

Three-dimensional wireframe reconstructions were used to examine the relationship between the anatomical localization of electrode sites and the cerebrovascular response which was elicited by electrical stimulation of the dorsal raphe nucleus (DRN). Reconstructions of the rat brain and DRN were done from atlas plates and from Nissl-stained coronal sections (100-micron increments). Data points were entered and three-dimensional reconstructions were performed using commercially available software and a personal computer. Display of the entire brain yielded views which obscured visualization of the DRN. The data file was edited to reduce the number of contours without affecting the display resolution of the DRN. Selective display of the DRN and electronic rotation from the coronal to a sagittal view revealed a functional organization of the cerebral blood flow responses which was not apparent in two-dimensional coronal sections.

Animals↗
PubMed1993

Laparoscopic-assisted bowel surgery.

The use of laparoscopic surgical techniques is now being applied to a variety of operations traditionally performed in an open fashion. Twenty patients underwent laparoscopic-guided large and small bowel surgery at our institution from March 1991 to April 1992. The indications for surgery included polyps, obstruction, bleeding, and perforation, and pathologic diagnoses included benign polyps, lipomas, inflammatory bowel disease, perforation of a jejunal diverticulum, colonic arteriovenous malformations, and adenocarcinoma. Mobilization of the colon, ligation of the mesentery, and closure of the mesenteric defect were performed using the laparoscopic equipment. One trocar site was enlarged to 3 cm to deliver the bowel through the abdominal wall. All anastomoses were hand-sewn. Postoperative hospitalization ranged from 2 to 31 days (median, five days). No mortality was noted, and morbidity was 20 percent. We conclude that laparoscopic-guided bowel surgery is technically feasible and should translate into shorter hospitalization and less patient discomfort.

Aged↗
PubMed1993

Cell division and transcription of ftsZ.

For normal cell division, the ftsZ gene must be transcribed from a number of promoters that are located within the proximal upstream genes (ddlB, ftsQ, and ftsA). We show that the main promoters have identical responses to changes in growth rate, i.e., under all conditions, the frequency of transcription per septum formed is approximately constant and independent of cell size or growth rate per se. We also show that transcription from these promoters is independent of stationary-phase transcription factor sigma s.

Bacterial Proteins↗
PubMed1993

Assessment of tennis elbow using the Marcy Wedge-Pro.

The Marcy Wedge-Pro (MWP), a device used in training by tennis players, was employed in the assessment of tennis elbow. The MWP was used to measure the ability of patients to perform wrist extension exercises, since pain resulting from this specific activity is a prominent symptom of the condition. The MWP results were compared with clinical measures and found to identify accurately patients who responded to treatment (P < 0.05). This study illustrates the potential of the MWP to assess tennis elbow quantitatively.

Adult↗
PubMed1993

Leisure-related peer preference choices of individuals with Down syndrome.

Although full participation in community life should be available to all individuals with mental retardation, some may prefer segregated participation in selected activities. Freedom of choice is particularly important in leisure activities. In this exploratory study we investigated whether individuals with Down syndrome would prefer to participate in bowling with other people who had Down syndrome or with people who had no apparent mental retardation. Structured interviews, in conjunction with videotapes of two bowling groups, revealed that 15 of the 21 adult subjects preferred to bowl with others who had Down syndrome. If either segregated or integrated activities are denied to adults with mental retardation, their opportunities for experiencing the benefits of freely chosen leisure participation are also systematically denied.

Adult↗