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Biomedical subjects

D K Smith

Publications and source records attributed to D K Smith.

At least 109 records · Page 6Linked to original sources
PubMed1989

Effects of a scaphoid waist osteotomy on carpal kinematics.

The effects of a scaphoid osteotomy on the kinematics of the carpal bones were determined in five cadaveric wrist specimens. Minute radiographic markers were inserted into the distal radius and selected carpal bones through limited arthrotomies between the intercarpal ligaments. Simultaneous biplanar radiographs were obtained in neutral and the extreme wrist positions of extension, flexion, radial deviation, and ulnar deviation, both before and after a scaphoid waist osteotomy. The positions of each of the carpal markers and their corresponding carpal bones were digitized for each wrist position , and a computer-assisted motion analysis was performed for each specimen before and after transverse scaphoid waist osteotomy. Following the osteotomy, there was a tendency for the scaphoid osteotomy to collapse into a dorsally angulated or "humpback collapse" deformity during each extreme wrist position. There was also multiplanar osteotomy site motion as well as complex collapse deformities of the midcarpal joint associated with loss of the mechanical tie-rod function of the scaphoid. These findings reveal the importance of the scaphoid in maintaining normal kinematics and the inherent instability of these fractures with loss of scaphoid integrity.

Carpal Bones↗
PubMed1989

The effects of simulated unstable scaphoid fractures on carpal motion.

The kinematics of five fresh frozen wrist specimens were studied before and after a simulated scaphoid waist fracture. To determine the change in wrist motion and fracture site characteristics associated with an unstable wrist, the relative motion of each carpal bone was determined from the movement of implanted carpal markers on biplanar radiographs obtained in neutral and the four extreme wrist positions. The kinematics of the wrist in our specimens before the osteotomy were similar to previous studies. After the osteotomy, the proximal and distal segments of the scaphoid moved independently. The distal scaphoid assumed a relatively flexed stance and displayed increased motion. The proximal scaphoid fragment and lunate assumed a relatively extended stance and displayed less motion after the osteotomy. These kinematic abnormalities produced significant interfragmentary motion that would be expected to complicate normal fracture healing. The spontaneous collapse of the two scaphoid fragments produced a dorsal angulation or "humpback" deformity that simulated the clinical situation of displaced scaphoid nonunions. The scaphoid serves an important role maintaining normal alignment of the carpal bones and producing normal wrist motion.

Biomechanical Phenomena↗
PubMed1989

Scaphoid malunion.

Forty-five patients with 46 scaphoid fractures were studied more than 6 months after union by clinical examination and trispiral tomography. Twenty had normal scaphoid alignment with lateral intrascaphoid angles less than 35 degrees; the rest had varying degrees of increased flexion angulation of the scaphoid, ranging from 36 degrees to 60 degrees. Increasing lateral scaphoid angulation, eventually resulting in a "humpback" deformity, was associated with progressively poor clinical and radiographic results. There were satisfactory clinical outcomes in 83% and posttraumatic arthritis in only 22% of those with normal scaphoid anatomy. Those with greater than 45 degrees of lateral intrascaphoid angulation present at the time of union had a satisfactory clinical outcome in 27% and posttraumatic arthritis in 54%. Union alone is an insufficient criterion for success in treating scaphoid fractures.

Adolescent↗
PubMed1989

Trace element status in multiple sclerosis.

We compared trace element status in multiple sclerosis (MS) patients (n = 27) with and without treatment with corticosteroids and groups of healthy subjects. Concentrations of plasma ceruloplasmin, selenium, and zinc and erythrocyte (RBC) glutathione peroxidase, Se, and Zn were similar in all groups. RBC copper concentrations were significantly lower in MS patients than in control subjects (mean +/- SEM: 0.048 +/- 0.005 vs 0.060 +/- 0.002 mumol/g Hb) because of decreased RBC Cu with steroid therapy. RBC Zn-Cu ratios were significantly higher (14.9 +/- 1.0 vs 10.1 +/- 0.3) in MS patients than in control subjects, differing in both groups of MS patients. In MS and control subjects, RBC Cu correlated significantly with RBC Zn (r = 0.56, 0.49). Disease acuity and disability had no effect on trace-mineral status. These data suggest that in MS there is altered Cu and Zn homeostasis that may cause or result from the disease and is influenced by corticosteroid therapy. Systemic trace element alterations might provide clinically useful markers of MS.

Adolescent↗
PubMed1989

Scaphoid anatomy: evaluation with complex motion tomography.

Complex motion tomography was used to study the normal orientation of the axes of the proximal and distal scaphoid poles as a basis for comparison with displaced or malunited scaphoid fractures. Biplanar tomograms of 10 normal wrists were evaluated by seven physicians with the use of two standardized measurement techniques. The reference planes used for the first technique were the volar cortical surface of the proximal scaphoid and the dorsal cortical surface of the distal scaphoid. The apparent angulation between the reference planes with this technique averaged 32 degrees +/- 5 degrees on the sagittal view and 40 degrees +/- 3 degrees on the coronal view. The second technique used the orientation of the proximal articular surface relative to the distal articular surface of the scaphoid. The angulation between the axes averaged 24 degrees +/- 5 degrees in the sagittal plane and 40 degrees +/- 4 degrees in the coronal plane.

Carpal Bones↗
PubMed1989

A validity study of the Stanford-Binet: Fourth Edition with students with learning disabilities.

This study compared the performance of 18 elementary-age students with learning disabilities on the Stanford-Binet Intelligence Scale: Fourth Edition and the Kaufman Assessment Battery for Children. Correlations (corrected for restriction of range) between the two instruments were strong, r = .74, p less than .001 for Test Composite/Mental Processing Composite and r = .85, p less than .001 for Test Composite/Achievement.

Child↗
PubMed1989

Topical zinc and delayed hypersensitivity responsiveness.

The ability of topical zinc to enhance the DHR to skin test antigens may be a simple method of evaluating functional zinc status. Additional testing is required to determine the sensitivity and specificity of this technique. In addition to zinc, other nutrient deficiencies such as protein deficiency may suppress DHR. Because of this and because of the variability among individuals in degree of reactiveness, each patient should serve as his/her own control, with zinc-treated and nontreated skin test sites being evaluated simultaneously.

Adult↗
PubMed1989

Conservative treatment for adenocarcinoma of the pancreas.

The records of 71 patients with the diagnosis of adenocarcinoma of the pancreas were reviewed. Seventeen patients were treated without surgery, 13 underwent exploratory laparotomy for diagnosis with no further palliative or curative operative procedure, six underwent pancreaticoduodenal resection, and 35 patients had a palliative gastric and/or biliary bypass procedure at initial operation. No preoperative signs or symptoms, routine laboratory tests, or radiologic evaluation were helpful as early diagnostic or prognostic indicators. Surgical mortality rates were not significantly different among the four groups; however, the survival time differences between the palliative group (4.8 mo) and the medically managed group (2.0 mo) was significant (p = 0.01 chi 2). Surgical morbidity did not differ significantly among the four groups of patients. The implications of these data in the treatment of patients with adenocarcinoma of the pancreas are discussed.

Adenocarcinoma↗
PubMed1988

Epidemiology of human bites to children in a day-care center.

The purpose of this study was to examine the epidemiology of human bites to children in a day-care center over a one-year period. This was a cohort study based on the injury log maintained on a daily basis by staff of the day-care center, as required by state II-censure law. A total of 224 children was enrolled in the center during the study period: 29 infants (ages 0 to 16 months), 62 toddlers (16.1 to 30 months), and 133 preschoolers (30.1 to 72 months). One hundred four children were bitten one or more times by other children in the center, with a total of 347 bites. The bite rates (defined as number of bites per 100 child days of enrollment in the center) varied significantly by age group but not by gender for initial or first-time bites, with toddlers having the highest rate and preschoolers the lowest (infants, 0.7129; toddlers, 1.3672; preschoolers, 0.4193). Total bite rates (which took into account multiple bites per child over the 12-month study period) varied significantly by age group, with toddlers having the highest rate per 100 days of enrollment and preschoolers the lowest (infants, 2.1931; toddlers, 3.1300; preschoolers, 0.5611). Males and females differed significantly in total bite rates per 100 enrollment days within the toddler age group (males, 3.6683; females, 2.3096) but not within the other two age groups. None of the demographic characteristics available in this study distinguished between children who were bitten compared with those who were not bitten with the exception of number of days of enrollment. The circumstances surrounding the biting events were examined with respect to the activity of the child when bitten, the victim's location when bitten, body part bitten, and treatment by staff. The results of this study raise policy questions about treatment protocols for human bites of children in group child-care settings, the routine recording of biting events, and the ethics and practice of reporting such events to parents.

Bites and Stings↗
PubMed1988

Comparison of K-ABC performance between at-risk and normal preschool children.

This study examined differences in K-ABC performance between at-risk (n = 44) and normal (n = 49) preschool children. For the group at-risk, all of the mean global scores on the K-ABC clustered around a standard score of approximately 90. The normal group's mean scores were 15 to 21 standard-score points higher and clustered near 110. The results of t tests for independent samples indicated that the normal group's scores on both the global scales and K-ABC subtests were significantly higher than the at-risk group's scores in nearly every instance. Correlations among scores were consistent with previous findings for preschoolers on the K-ABC. For the normal group, correlations obtained among the global scales were nearly identical to those reported for the standardization sample. For the at-risk group, however, the correlation of .75 between Sequential processing and Achievement was higher than that (.58) between Simultaneous processing and Achievement.

Achievement↗
PubMed1987

External fixation of the upper extremity.

External fixation of forearm and arm fractures is an excellent treatment option, particularly in compound, comminuted fractures that result from high-energy trauma. Limb salvage and good function have been achieved in 75% of cases by applying the principles outlined. Problems with delayed bone union have been recognized and emphasize the importance of supplemental bone grafting. A number of external fixation systems are applicable to these upper limb fractures, and the authors have not found one system superior to the others. Open pin insertion is preferred, and pins (three proximal and three distal) are ideally placed near the fracture site for optimal stability.

Arm Injuries↗
PubMed1986

Selenium status of malnourished hospitalized patients.

We evaluated selenium (Se) status of 44 hospitalized patients with protein-energy malnutrition. The patients were assigned to "normal" or "low" Se groups-1 and 2, respectively-based on whether the plasma Se level exceeded or was below the value of the mean-2SD of healthy Georgians'. Plasma and erythrocyte Se levels correlated significantly (r = .52, P less than .01). Erythrocyte glutathione peroxidase activity was highly correlated with plasma Se (r = .68) in group 2; there was no significant correlation between these parameters in group 1. In group 2 the mean plasma prealbumin level was significantly lower, and the mean corpuscular volume and serum glutamic oxaloacetic transaminase level were significantly higher compared to group 1. Other nutritional parameters did not correlate with Se status. Concomitant deficiencies of other nutrients were common in both patient groups. Se levels may relate to protein status, and abnormal hematologic and hepatic parameters may reflect low Se status and/or protein-energy malnutrition. Low Se status is common in malnourished patients from a low Se area, and Se supplementation should be included in their nutritional-repletion regimens.

Adult↗
PubMed1985

Effects of N-ethylmaleimide on ouabain-insensitive cation fluxes in human red cell ghosts.

In red cells of several species, the sulfhydryl reagent N-ethylmaleimide activates a Cl- -dependent, ouabain-resistant K+ transport pathway. Here we report our attempts to demonstrate ouabain-resistant Cl- -dependent K+ fluxes stimulated by N-ethylmaleimide in resealed human red cell ghosts using Rb+ as a K+ analogue. In contrast to intact cells, the rate constants of the base level Rb+ efflux in ghosts were similar in NaNO3 and NaCl (okRb = 0.535 +/- 0.079 h-1 and 0.534 +/- 0.085 h-1, respectively), while 1 mM N-ethylmaleimide stimulated Rb+ efflux strongly in NaNO3 (okRb = 14.26 +/- 1.32 h-1) and moderately in NaCl (okRb = 2.73 +/- 0.54 h-1). This effect was dependent on the presence of internal ATP. Stimulation of Rb+ efflux was observed in the presence of greater than or equal to 0.2 mM N-ethylmaleimide and increased at pH values approaching 8.0, consistent with titration of SH groups. N-Ethylmaleimide-stimulated Rb+ efflux was approx. 50% inhibited by 100 microM quinine sulfate whereas 1 microM bumetanide had no effect. In NaCl the N-ethylmaleimide-stimulated efflux saturated with initial internal ghost Rb+ concentration, but rates increased linearly in NaNO3. Replacement of external Na+ with glucamine or choline decreased the N-ethylmaleimide-stimulated Rb+ efflux, suggesting a role for external Na+. N-Ethylmaleimide-stimulated Rb+ efflux was greater in buffers with lipophilic anions such as SCN- or NO3- than in solutions with Cl- or acetate. However, the cation selectivity of the pathway studied was low, as Li+ efflux was also stimulated by N-ethylmaleimide. We conclude that the effect of N-ethylmaleimide on ouabain-resistant cation effluxes of human red cell ghosts is very different from the selective action of N-ethylmaleimide on Rb+ influxes in intact red cells.

Acetates↗
PubMed1983

Hypothermia in a patient with anorexia nervosa.

A young woman with anorexia nervosa had severe recurrent hypothermia. Initial evaluation revealed a thiamine deficiency. Administration of pharmacologic doses of thiamine improved voluntary food intake, and her temperature normalized. Following the restoration of body weight, withdrawal of supplemental thiamine produced a clinical relapse. After reinstitution of supplemental thiamine, the patient again became asymptomatic until she chose to consume a calorically-restricted diet. With progressive weight loss, hypothermia recurred and was unresponsive to thiamine therapy. Fortuitously, the patient's intake of sucrose was abruptly increased, and her body temperature normalized within seven days. The potential roles of thiamine and carbohydrate in thermoregulation are discussed.

Adult↗
PubMed1983

Sulfhydryl reagents induce altered spectrin self-association, skeletal instability, and increased thermal sensitivity of red cells.

Incubation of erythrocytes with the sulfhydryl reagent N-ethyl-maleimide (NEM) results in altered spectrin self-association and formation of dimers on the membrane. Skeletons isolated from these cells exhibit marked skeletal instability. In addition, NEM treatment induces increased thermal sensitivity of both cells and purified spectrin. These effects were not produced in aerobically incubated glucose-6-phosphate dehydrogenase deficient cells and were therefore presumably not due to depletion of intracellular reduced glutathione. These effects were produced by another permeant sulfhydryl reagent, monobromobimane, but not by its membrane-impermeant derivative. We conclude that spectrin sulfhydryl groups play an important role in spectrin self-association and thermal stability.

Bridged Bicyclo Compounds↗