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Biomedical subjects

D K Smith

Publications and source records attributed to D K Smith.

At least 19 recordsLinked to original sources
PubMed1992

Transtriquetral perihamate ulnar axial dislocation and palmar lunate dislocation.

Transtriquetral perihamate ulnar axial dislocation associated with palmar lunate dislocation is a rare condition. We could find no other similar cases reported. The mechanism of injury was a combined anteroposterior crushing force that caused axial disruption of the carpus and the metacarpals and wrist hyperextension that caused the transtriquetral lunate dislocation. Our patient was treated with open reduction and internal fixation with good result.

Adult↗
PubMed1992

Vitamin A in hypercholesterolemia.

This study evaluated the relationship between plasma vitamin A and cholesterol in 48 patients with hypercholesterolemia studied before and after treatment with a cholesterol-lowering diet, with or without lipid-lowering medication. Plasma vitamin A levels were higher in hypercholesterolemic subjects than in healthy controls (2.58 +/- 0.15 vs. 1.82 +/- 0.14 mmol/L, p = 0.025) despite similar values for retinol binding protein (RBP). Successful cholesterol lowering, defined as greater than 25% reduction in low density lipoprotein cholesterol, was achieved in 16 patients. In this subset, plasma vitamin A declined from 3.00 +/- 0.32 (pretreatment) to 2.34 +/- 0.15 mmol/L (post treatment; p = 0.018). A nonsignificant increase in RBP was observed, resulting in a significant decrease in the molar ratio of vitamin A to RBP (1.05 +/- 0.06 vs. 0.80 +/- 0.05, p = 0.013). These data suggest an interaction between vitamin A and cholesterol that is independent of the transport mechanisms for vitamin A in association with chylomicrons (post absorptive) and with RBP. Further examinations of the form or forms of vitamin A (retinol, retinyl ester), its distribution within the plasma lipoproteins, and the mechanisms of origin and removal are warranted to explain these findings.

Anticholesteremic Agents↗
PubMed1992

Escherichia coli has two homologous glutamate decarboxylase genes that map to distinct loci.

Degenerate oligonucleotides based on the published Escherichia coli glutamate decarboxylase (GAD) protein sequence were used in a polymerase chain reaction to generate a DNA probe for the E. coli GAD structural gene. Southern blots showed that there were two cross-hybridizing GAD genes, and both of these were cloned and sequenced. The two GAD structural genes, designated gadA and gadB, were found to be 98% similar at the nucleotide level. Each gene encoded a 466-residue polypeptide, named, respectively, GAD alpha and GAD beta, and these differed by only five amino acids. Both GAD alpha and GAD beta contain amino acid residues which are highly conserved among pyridoxal-dependent decarboxylases, but otherwise the protein sequences were not homologous to any other known proteins. By restriction mapping and hybridization to the Kohara miniset library, the two GAD genes were located on the E. coli chromosome. gadA maps at 4046 kb and gadB at 1588 kb. Neither of these positions is in agreement with the current map position for gadS as determined by genetic means. Analysis of Southern blots indicated that two GAD genes were present in all E. coli strains examined, including representatives from the ECOR collection. However, no significant cross-hybridizing gene was found in Salmonella species. Information about the DNA sequences and map positions of gadA and gadB should facilitate a genetic approach to elucidate the role of GAD in E. coli metabolism.

Amino Acid Sequence↗
PubMed1992

HIV disease as a cause of death for African Americans in 1987 and 1990.

Using death certificate data for 1987 and 1988 from the National Center for Health Statistics, combined with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) surveillance data through December 1990 from the Centers for Disease Control, this article reports ranked mortality causes as a measure of the impact of the HIV epidemic within the African-American community. In 1987, while HIV/AIDS ranked 15th as a cause of death for all Americans, for African Americans the disease ranked 10th overall (third for African-American men, fifth for African-American women between 25 and 34 years of age, and ninth for African-American children ages 0 to 14). By 1990, it can be estimated that for all Americans HIV disease was the eight leading cause of death, but for African-Americans it ranked sixth overall. For African-American men between the ages of 35 and 44, HIV disease became the leading cause of death, accounting for 23.5% of all deaths. This disease was the second leading cause of death for African-American men and women between the ages of 25 and 35, and the eighth leading cause of death for African-American children ages 0 to 14. The implications of these findings are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Physician's and dietitian's role in obese care.

In the Surgeon General's Report on Nutrition and Health, of the ten leading causes of death in the United States, five are nutrition related. Instead of nutritional deficiencies as seen in the 1940s, the national diet has shifted to dietary excesses and imbalances. Dietary excesses and imbalances are reflected in obesity, a major health problem affecting approximately 30% of the United States' population. Unfortunately, the diet industry is not regulated and, hence, patients have many avenues from which to choose. Many of these leave patients lost and confused as to why they have failed in maintaining their weight loss. It is well documented that the recidivism rate in the obese is high with only 5% maintaining their weight loss after one year. The following is a review of the physician's and dietitian's roles in long-term weight maintenance.

Dietetics↗
PubMed1992

Community resources in obese care.

Community resources can augment care provided by physicians and dietitians for the obese. The well-distributed community resources in Florida are reviewed. They are well-established and provide emotional support, peer group dynamics, a variety of formats and prices, and information about food and life-style changes.

Humans↗
PubMed1990

External fixation of high-energy upper extremity injuries.

Forty patients with high-energy upper extremity injuries involving the humerus and forearm bones were treated by primarye external fixation. Concomitant soft tissue or neurovascular injuries were rated by the Gustilo classification, and this rating correlated well with the final results: three fractures were Gustilo type I, two fractures were type II, and 35 were type III (IIIA, nine fractures; IIIB, eight; and IIIC, 18). Immediate external fixation, open wound treatment, delayed bone grafting, and late internal fixation led to good to excellent results in 73%. Complications were either minor (related to the external fixation and included pin loosening, 20%) or significant (osteomyelitis, 3%).

Adolescent↗
PubMed1990

Acoustic reflectometry for assessment of hearing loss in children with middle ear effusion.

We sought associations between acoustic reflectometry and hearing loss in ears with and without middle ear effusion in 137 New Zealand children ages 3 to 16 years. Reflectometry was significantly associated with conductive hearing loss. These associations were present in the entire sample; correlation coefficients varied between 0.31 at 2000 Hz (P less than 0.001) and 0.55 for a three frequency pure tone average (P less than 0.001). The associations persisted for the sample of ears deemed to be filled entirely by effusion; correlation coefficients varied between 0.27 at 4000 Hz (P = 0.026) and 0.47 at 500 Hz (P less than 0.001). Using a reflectivity of 6.0 or greater to detect a three frequency pure tone average loss of 30 dB or more, the sensitivity was 88% and the specificity was 44%. The technique of acoustic reflectometry should be explored and extended to permit rational decisions about management of middle ear effusions.

Adolescent↗
PubMed1990

The knee after partial meniscectomy: MR imaging features.

The magnetic resonance (MR) examinations of 51 menisci treated by means of partial meniscectomy were reviewed. Menisci were divided into three groups: group 1, near normal length without osteoarthritis; 2, substantially shortened without osteoarthritis; and 3, any length with osteoarthritis. Group 1 menisci resembled normal menisci except for mild shortening and frequent signal inhomogeneity (56%). Group 2 menisci varied in appearance, with marked contour irregularity simulating fragmentation in 40% of segments despite a normal postoperative appearance at follow-up arthroscopy. Group 3 menisci appeared similar to menisci of the same length without osteoarthritis. Arthroscopic correlation, available for 23 menisci (45%), confirmed the MR diagnosis of a tear in 11 and no tear in 49 and revealed an unsuspected tear in three meniscal segments. There is a spectrum of normal MR appearances after partial meniscectomy. Standard MR criteria can be used to diagnose tears in the absence of marked contour irregularity; however, the diagnosis of tears of segments with marked contour irregularity must be made cautiously, since this irregularity can mimic a tear and was not predictive of an arthroscopically visible tear.

Adolescent↗
PubMed1990

Dorsal lunate tilt (DISI configuration): sign of scaphoid fracture displacement.

Excessive dorsiflexion (dorsal tilting) of the lunate on a lateral wrist radiograph can be an important sign of carpal injury. Lunate dorsiflexion is a well-recognized sign of an intercarpal ligamentous injury pattern known as dorsal intercalated segment instability (DISI). It is less well recognized that excessive dorsal tilting of the lunate (DISI configuration) can also be produced by displacement of a scaphoid waist fracture. Since the management and prognosis of displaced scaphoid fractures may be quite different from those for nondisplaced fractures, radiologists can make an important contribution by recognizing dorsal tilting of the lunate and appreciating that it may be an important, indirect sign of scaphoid fracture displacement, which may not be directly visualized with standard wrist radiography. In this setting, computed tomography or complex motion tomography may be helpful for further evaluation of the scaphoid fracture.

Aged↗
PubMed1990

Subtalar arthrosis: evaluation with CT.

The surgical implantation of a Silastic wedge into the lateral subtalar joint (subtalar arthrosis) is designed to restrict the osseous malalignment associated with a flexible or neurogenic flatfoot deformity. We used CT to examine patients who had persistent pain after a subtalar arthrosis and retrospectively reviewed our experience with CT scans of 13 subtalar implants (seven patients) during a 3.5-year period. The CT scans of four asymptomatic subtalar implants showed each implant in the expected position and orientation, and the findings were considered normal. Conversely, the findings on CT scans of all nine painful implants (seven patients) were interpreted as abnormal. The scans showed oblique orientation of four implants (44%), loosening of three implants (33%), extruded methyl methacrylate in the subtalar joint in two implants (22%), and abnormal calcaneal recession in two implants (22%). Five of the nine painful implants were revised with improvement or resolution of symptoms. Our experience suggests that CT scanning of the subtalar joint can show the position and orientation of a subtalar implant and identify causes of persistent pain after a subtalar arthrosis.

Adolescent↗
PubMed1989

Phylogenetic comparative analysis and the secondary structure of ribonuclease P RNA--a review.

The most incisive a priori approach to inferring the higher order structure of large RNAs has proven to be the use of phylogenetic comparisons. This article provides guidelines to the method, using as an illustration the elucidation of the secondary structure of the catalytic RNA subunit of ribonuclease P (RNase P). The resultant structure is compared to the possibilities that are predicted thermodynamically for the RNase P RNA sequences of nine eubacteria.

Bacillus subtilis↗
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↗