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Biomedical subjects

D G Smith

Publications and source records attributed to D G Smith.

At least 127 records · Page 7Linked to original sources
PubMed1997

Diagnostic utility of the history and physical examination for peripheral vascular disease among patients with diabetes mellitus.

BACKGROUND: We assessed the value of the medical history and physical examination in the diagnosis of peripheral vascular disease in diabetic subjects. METHODS: We performed a cross-sectional study in 631 diabetic veteran enrollees of a general internal medicine clinic that compared data obtained from a history and clinical evaluation with the presence of severe peripheral vascular disease defined as an ankle-arm index (AAI) < or = 0.5 derived from Doppler blood pressure measurement. RESULTS: We identified 90 limbs with an AAI < or = 0.5. Results presented below apply to the right leg, but do not differ from the left. Diminished or absent foot peripheral pulses (sensitivity 65%, specificity 78%), venous filling time > 20 sec (sensitivity 22%, specificity 93.9%), age > 65 years (sensitivity 83%, specificity 54%), claudication symptoms in < 1 block (sensitivity 50%, specificity 87%), and patient reported history of physician diagnosed peripheral vascular disease (PVD) (sensitivity 80%, specificity 70%) had the largest positive (or smallest negative) likelihood ratios. Capillary refill time > 5 sec or foot characteristics (absent hair, blue/purple color, skin coolness, or atrophy) conveyed little diagnostic information. Individual factors did not change disease probability to a clinically important degree. A stepwise logistic regression model identified four factors significantly (p < 0.05) associated with low AAI: absent or diminished peripheral pulses, patient reported history of PVD, age, and venous filling time. Substitution of < 1 block claudication for PVD history in this model resulted in a small reduction in model accuracy. CONCLUSIONS: Many purportedly useful historical and exam findings need not be elicited in diabetic patients suspected of having severe peripheral vascular disease, since most information related to probability of this disorder may be obtained from patient age, self-reported history of physician diagnosed PVD (or < 1 block claudication), peripheral pulse palpation, and venous filling time.

Aged↗
PubMed1997

Prevalence of radiographic foot abnormalities in patients with diabetes.

Clinicians are increasingly aware that mechanical aspects of foot deformities, such as Charcot changes, clawtoes, bunion deformities, or cavus or planus foot deformities, might have an impact on the occurrence, potential healing, and recurrence of foot ulcers. We report the prevalence of plain radiographic changes and attempt to rate the severity of those deformities in the feet of 456 diabetic veteran medicine clinic enrollees. All 456 radiographs were reviewed by orthopaedic surgeons to specifically identify Charcot changes, presence of arterial calcification, dislocation of the lesser toe metatarsophalangeal joints, hallux interphalangeal joint dislocation, and radiographic evidence of previous surgery. Radiographs of 428 patients were taken while weight-bearing, and these were reviewed to quantify hallux valgus angles, intermetatarsal 1-2 angles, fifth metatarsal-proximal phalangeal angles, second metatarsal lengths, lateral talocalcaneal and talar-first metatarsal angles, and claw toe deformities. The prevalence of Charcot changes was 1.4% (six subjects), and all had radiographic evidence of midfoot Charcot changes. Other deformities, such as clawtoes, hallux valgus, lesser toe joint dislocations, and alterations in arch height, are more common in veterans with diabetes.

Adult↗
PubMed1997

Risk factors for diabetic peripheral sensory neuropathy. Results of the Seattle Prospective Diabetic Foot Study.

OBJECTIVE: To identify risk factors for diabetic lower-extremity peripheral sensory neuropathy prospectively in a cohort of U.S. veterans with diabetes. RESEARCH DESIGN AND METHODS: General medicine clinic outpatients with diabetes were followed prospectively for the development of insensitivity to the 5.07 monofilament on the foot. RESULTS: Of 775 subjects, 388 (50%) had neuropathy at baseline. Of the 387 subjects without neuropathy at baseline, 288 were followed up, and of these, 58 (20%) developed neuropathy. Multivariate logistic regression modeling of prevalent neuropathy controlling for sex and race revealed independent and significant associations with age, duration of diabetes, glycohemoglobin level, height, history of lower-extremity ulceration, callus, and edema; an independent and inverse correlation was noted with ankle-arm index. Risk factors for incident neuropathy in multivariate logistic regression included age, baseline glycohemoglobin level, height, history of ulcer, and CAGE screening instrument alcohol score; current smoking and albumin level were inversely associated with risk. CONCLUSIONS: Poorer glycemic control increases the risk of neuropathy and is amenable to intervention. Height and age directly increase risk of neuropathy and may help identify patients at risk. A proportion of neuropathy in diabetic veterans is probably due to or worsened by alcohol ingestion. Neuropathy was less common in current smokers than subjects not currently smoking.

Age Factors↗
PubMed1997

Design and pilot testing of the DVA/Seattle Footwear System for diabetic patients with foot insensitivity.

Clinical epidemiology studies suggest the majority of lower limb amputations were preceded by a minor traumatic event, often footwear-related, and lower limb ulcers. To reduce foot trauma and ulcers, the diabetic patient with foot insensitivity has unique footwear needs. To address these needs for patients not requiring custom shoes, the DVA/Seattle Footwear System was developed. The six components of this system include: 1) a specially designed shoe last based on the geometry of the diabetic foot and research findings on foot regions at highest risk of ulceration, 2) a depth-inlay shoe, "Custom Stride by PRS," designed to be paired with either a custom-fabricated cork insole or a preformed polyurethane insole, 3) a laser digitizing system that captures 3-D plantar foot contours, 4) DVA/Seattle ShapeMaker software adaptation for modifying plantar surface contours and applying free-form and template modifications to increase or relieve loading, 5) software that translates files into code used by a milling machine to define the cutting path and carve cork blockers into custom insoles, and 6) a preformed polyurethane insole thicker than a typical insole to accommodate the extra volume and the interior dimensions of the shoe. A 6-month pilot cross-over trial of 24 diabetic male veterans without prior foot ulcers was conducted to determine the feasibility of producing, and the safety of wearing, these depthinlay shoes and both types of insoles. During the first 4 weeks, patients were assigned to the study shoes and one type of insole. During the next 4 weeks, they wore the other type of insole, and during the final 4 months, they chose which pair of insoles to wear with the study shoes. Over 150 person-months of footwear observation revealed no breaks in the cutaneous barrier with use of either cork or polyurethane insoles and the study shoes. Patient compliance with the footwear was 88%. Patients were highly satisfied with the appearance, stability, and comfort of the shoes and the comfort of both types of insole. However, 75% of the patients noted that the study shoes felt heavier than their customary shoes. Further research is needed to determine the long-term effectiveness of footwear in prevention of foot ulcers in the population at highest risk for diabetic reulceration and amputation.

Aged↗
PubMed1997

Distribution of sequence variation in the mtDNA control region of Native North Americans.

The distributions of mtDNA diversity within and/or among North American haplogroups, language groups, and tribes were used to characterize the process of tribalization that followed the colonization of the New World. Approximately 400 bp from the mtDNA control region of 1 Na-Dene and 33 Amerind individuals representing a wide variety of languages and geographic origins were sequenced. With the inclusion of data from previous studies, 225 native North American (284 bp) sequences representing 85 distinct mtDNA lineages were analyzed. Mean pairwise sequence differences between (and within) tribes and language groups were primarily due to differences in the distribution of three of the four major haplogroups that evolved before settlement of the New World. Pairwise sequence differences within each of these three haplogroups were more similar than previous studies based on restriction enzyme analysis have indicated. The mean of pairwise sequence differences between Amerind members of haplogroup A, the most common of the four haplogroups in North America, was only slightly higher than that for the Eskimo, providing no evidence of separate ancestry, but was about two-thirds higher than that for the Na-Dene. However, analysis of pairwise sequence divergence between only tribal-specific lineages, unweighted for sample size, suggests that random evolutionary processes have reduced sequence diversity within the Na-Dene and that members of all three language groups possess approximately equally diverse mtDNA lineages. Comparisons of diversity within and between specific ethnic groups with the largest sample size were also consistent with this outcome. These data are not consistent with the hypothesis that the New World was settled by more than a single migration. Because lineages tended not to cluster by tribe and because lineage sharing among linguistically unrelated groups was restricted to geographically proximate groups, the tribalization process probably did not occur soon after settlement of the New World, and/or considerable admixture has occurred among daughter populations.

Anthropology, Cultural↗
PubMed1997

The traumatic anterior overbite.

The position of the anterior teeth and skeletal base relationship establish many of our facial characteristics, yet these same tooth positions can result in a range of dental problems that are often specific for a particular incisal relationship. Excessive loss of tooth tissue on various surfaces may result in trauma to the soft tissue and temporomandibular joint dysfunction. A range of treatment options may be required and can often be conveniently classified by the form of incisal relationship.

Crowns↗
PubMed1996

Characterization of an apparent hotspot for spontaneous mutation in exon 5 of the Chinese hamster APRT gene.

We describe an apparent hotspot for spontaneous deletions and base substitution mutations at a TTC trinucleotide direct repeat/MboII restriction site in exon 5 of the Chinese hamster APRT gene, in a region with the potential to form a relatively stable, quasipalindromic, stem-loop structure. The recurrent 3 bp TTC deletions observed at this site, which account for approx. 20% of the characterized spontaneous APRT deletions in hemizygous CHO cell lines, represent the only spontaneous deletion events that have been recovered more than once at this locus. A total of 11 independently derived, spontaneous CHO cell APRT mutants with identical 3 bp TTC deletions at this exon 5 MboII site, plus another five mutants that have single base substitutions at this site have been identified among spontaneous mutant collections in several different laboratories. Intriguingly, each of the frequently deleted or mutated bases at this exon 5 deletion hotspot site would correspond to one of the unpaired bases within a single-stranded 'loop' region of a stable, quasipalindromic, stem-loop structure that can be formed by intrastrand pairing of inverted repeats in this portion of the APRT gene sequence. An identical TTC trinucleotide direct repeat sequence at the same site in exon 5 of the human APRT gene also appears to be a hotspot for spontaneous deletion.

Adenine Phosphoribosyltransferase↗
PubMed1996

Distribution of four founding mtDNA haplogroups among Native North Americans.

The mtDNA of most Native Americans has been shown to cluster into four lineages, or haplogroups. This study provides data on the haplogroup affiliation of nearly 500 Native North Americans including members of many tribal groups not previously studied. Phenetic cluster analysis shows a fundamental difference among 1) Eskimos and northern Na-Dene groups, which are almost exclusively mtDNA haplogroup A, 2) tribes of the Southwest and adjacent regions, predominantly Hokan and Uto-Aztecan speakers, which lack haplogroup A but exhibit high frequencies of haplogroup B, 3) tribes of the Southwest and Mexico lacking only haplogroup D, and 4) a geographically heterogeneous group of tribes which exhibit varying frequencies of all four haplogroups. There is some correspondence between language group affiliations and the frequencies of the mtDNA haplogroups in certain tribes, while geographic proximity appears responsible for the genetic similarity among other tribes. Other instances of similarity among tribes suggest hypotheses for testing with more detailed studies. This study also provides a context for understanding the relationships between ancient and modern populations of Native Americans.

DNA↗
PubMed1996

Predictors of transcutaneous oxygen tension in the lower limbs of diabetic subjects.

We examined neuropathy, ankle pressure index (API), and other factors as predictors of transcutaneous oxygen (TcPO2) in the lower limbs of 657 diabetic subjects. Eligible subjects underwent a clinical assessment that included three standard measures of autonomic neuropathy. TcPO2 measurements were performed at 37 degrees C and 44 degrees C at four lower limb locations. Associations between potential predictors and TcPO2 were tested using univariate and multivariate statistics. Mean TcPO2 at any site did not differ by presence of autonomic neuropathy at either temperature, except for a significantly lower value at 44 degrees C below the knee (56.5 versus 59.2 mmHg, p = 0.021). In multivariate analysis, autonomic neuropathy was significantly and independently related to leg 44 degrees C TcPO2 only (coefficient = -2.6734, p = 0.0182). Much stronger associations were seen between TcPO2 and age, ankle blood pressure, and relative body weight on the plantar foot; and between API, glycosylated haemoglobin, ankle blood pressure, and pedal oedema on the dorsal foot and leg. We conclude that factors related to lower limb TcPO2 vary depending on measurement site. Autonomic neuropathy is not an important determinant of TcPO2 in the feet of diabetic subjects. Although several predictors of TcPO2 were identified, most of the variance of this measurement remains unexplained.

Algorithms↗
PubMed1996

Increased mortality associated with diabetic foot ulcer.

The objective of this study was to evaluate the relationship between foot ulceration and short-term mortality in veterans of the American military services with diabetes mellitus. A total of 725 diabetic subjects participated in a prospective study of risk factors for lower extremity complications between 1990 and 1994. Mean follow-up was 691.8 days (+/-SD 339.9, range 28-1436 days). Subjects who died during follow-up (n = 72) had a similar mean duration of diabetes to those who survived (12.6 years vs 11.2), but their mean age was greater (65.9 years vs 63.2, p = 0.026). The relative risk (RR) of death was 2.39 (95% confidence interval (CI) 1.13 to 4.58) in the subjects who developed foot ulcer (n = 88) compared to those who did not. The risk of death for those with foot ulcer was 12.1 per 100 person-years of follow-up compared to 5.1 in those without foot ulcer. Cox regression analysis demonstrated a greater than two-fold increased risk of death in ulcerated subjects after adjustment for age; diabetes type, duration, and treatment; glycosylated hemoglobin level; history of lower extremity amputation; and cumulative pack years smoked. Higher ankle-arm index was significantly related to lower mortality risk, independent of foot ulcer occurrence. We conclude that foot ulcer and lower extremity vascular disease are related to a higher risk of death in diabetic subjects. The reasons for this excess mortality require further investigation.

Age Factors↗
PubMed1996

Lateral approach to the humeral shaft: an alternative approach for fracture treatment.

Indications for operative treatment of fractures of the shaft of the humerus have been well described. Anterolateral and posterior surgical approaches are generally preferred for fractures of the proximal/middle thirds and distal third of the humerus, respectively. Each approach has its advantages and disadvantages. We present an alternative, "lateral" approach to the humeral shaft. This approach allows supine positioning of the multiply injured patient and visualization of the radial nerve throughout the extent of the incision, and requires no muscle splitting.

Adult↗
PubMed1996

Pediatric amputation injuries: etiology, cost, and outcome.

OBJECTIVE: To provide a comprehensive profile of amputation injuries in children and adolescents. DESIGN: A retrospective case series. MATERIALS AND METHODS: All patients 18 years old or less, admitted to the regional Level I trauma center hospital with a traumatic amputation injury over a 10-year period (74 patients, 77 extremities) were included in the study. Etiology and mechanism of injury, length of hospital stay, number of surgeries and procedures, presence of infection, final outcome of injury (amputation vs. salvage), anatomic location of final outcome, and total charges were recorded for each patient. MEASUREMENTS AND MAIN RESULTS: There were 47 injuries to the upper extremity, and 30 to the lower extremity. The average length of stay was 11.3 days, with a mean of 4.3 procedures in 2.3 surgeries and average charges of $22,015. Twenty-two percent of the injuries were caused by power lawn mowers; all of these patients had amputations. Motor vehicle related crashes accounted for 16% of all injuries; 77% of these ultimately had amputations. Gunshot wounds had the highest mean length of hospital stay, surgery days, number of procedures, and charges. Out of 32 extremities that were revascularized for attempted salvage, 27 were successful (84%), all in the upper extremity, and all but one were digits. CONCLUSIONS: Injuries caused by a sharp mechanism with a smaller area of involvement are more likely to be successfully salvaged with revascularization, regardless of ischemic time. Long-term follow-up is needed to evaluate final functional and psychosocial outcome. Lawn mowers represent a serious hazard to children, and should be addressed through changes in engineering and parent education.

Accidents, Home↗
PubMed1996

Health and economic implications of a work-site smoking-cessation program: a simulation analysis.

In this article, we examine the health and economic implications of a workplace smoking-cessation program by using a simulation model that includes, among its novel features, consideration of long-term as well as short-term implications and evaluation of the effects of employee turnover on benefits derived by both the firm and the broader community. As a result of employee turnover, approximately half of the program-generated benefits are realized by the community outside the firm. Still, smoking cessation is a very sound economic investment for the firm, and is particularly profitable when long-term benefits are included, with an eventual benefit-cost ratio of 8.75. Saving life-years at a cost of $894 each, the program is more cost-effective than most of the conventional medical care covered by the firm's insurance. Nevertheless, the intervention successfully addresses only a fraction of the costs that smoking imposes on the firm.

Absenteeism↗
PubMed1996

A cost analysis of alprostadil in liver transplantation.

Alprostadil (prostaglandin E1) administration to liver transplant recipients has been shown to result in a significant reduction in the duration of hospital admission for transplantation, and in the need for re-operations (other than re-transplants) and renal support. To study the economic impact of this finding, we examined data from a controlled trial for all single-transplant surviving patients (42 alprostadil, 49 controls) for whom complete billing records were available for transplant days -2 to +150. All costs were measured in 1992 US dollars. Patients given alprostadil had lower total charges [mean +/- standard deviation (SD) $US175 297 +/- $US70 652] than patients given placebo (mean +/- SD $US225 672 +/- $US187 208) [p = 0.043]. The data suggest that the use of alprostadil may have a significant favourable impact on the cost of liver transplantation.

Alprostadil↗