Evaluation of Professional Ballet Dancers Body Posture During Barre Movements

Ballet dancers have finite careers due to the demands placed upon their bodies throughout years of training, study, and performance. The average age a dancer retires is 34 due to persistent stress on their joints and injuries due to mechanical overload or overuse. Proper form is crucial to prevent injury. The aim of this study was to establish benchmarks for normal movement patterns among professional dancers. Ten professional ballerinas were studied. Reflective markers were placed on the pelvis, left and right anterior superior iliac spine (ASIS), and posterior iliac spine (PSIS) to evaluate motion during Barre movements: plié, grand battement, and développé. Pelvis flexion/extension, mediolateral rotation, and torsion were analyzed. These motions test different skills. The plié is a controlled coordinated motion using both legs. The grand battement and développé both require leg extension, one with a quick motion that creates momentum and one using controlled motion that requires strength. Each requires core and pelvis stability to perform accurately and with less injury. Dancers' motions were consistent. Maximum pelvis range of motion for the plié, grand battement, and développé were 8.0, 42, and 50 deg, respectively. This represents usable benchmarks with which other dancers may be compared, for example, those who are at different levels of training, injured, predisposed to injury, or recovering from injury. Early recognition of pathologic movement patterns could benefit professional and amateur dancers by helping to prevent injuries, and potentially improve the quality and length of their careers.

Using PET/CT imaging to characterize 18 F-fluorodeoxyglucose utilization in fish

Fish are becoming an increasingly important research species as investigators seek alternatives to mammalian models. Combined positron emission tomography/computed tomography with ¹⁸F-fluorodeoxyglucose (FDG-PET/CT) is a powerful new technology that has been extensively applied for high-resolution imaging in mammals but not fish. CT scanning provides detailed anatomical three-dimensional imaging. PET scanning detects areas of cellular activity using radio-labelled molecular probes with specific uptake rates appropriate to the tissue involved. FDG-PET is used in oncology because tissues with high glucose uptake, such as neoplasms, are intensely radio-labelled. PET/CT combines the two technologies, so that images acquired from both devices are merged into one superimposed image, thus more precisely correlating metabolic activity with anatomical three-dimensional imaging. Our objective was to determine if fish can be viable replacement animals in cancer studies using this technique by analysing the similarities between fish and humans in glucose uptake in select organs across multiple fish species. Rapid, quantifiable glucose uptake was demonstrated, particularly in brain, kidneys and liver in all imaged fish species. Standard uptake values for glucose uptake in the major organ systems of fish were more similar to those of humans than mice or dogs, indicating that fish may serve as effective alternative animal models using this technology. Applications for this technique in fish may include oncogenesis and metabolism studies as well as screening for environmental carcinogenesis.

Internal/external rotation moment arms of muscles at the knee: moment arms for the normal knee and the ACL-deficient knee

Knowledge of the three-dimensional balance of loads at the knee joint is required to adequately assess the treatment and rehabilitation of the malfunctioning knee. This report focuses upon the moment arms for the knee in internal/external (IE) rotation motion. It augments prior work that defined flexion/extension moment arms. Muscle excursions and angular motion of the lower leg during IE rotation were measured in 17 fresh-frozen hemi-pelvis specimens. Moment arms were calculated as the derivatives of excursion with respect to the angle. Rotational motion was performed for the normal and anterior cruciate ligament (ACL)-deficient knee. Of the 13 muscles measured at the knee, seven were significant contributors to IE rotation: the biceps femoris long and short head externally rotate opposite the gracilis, sartorious, semimembranosis, semitendonosus and popliteus, functioning as internal rotators. Moment arm magnitudes were greatest with the knee in a flexed position (internal [external] rotators peaked at 70 degrees [90 degrees] flexion). At 30 degrees flexion, the IE rotation moment arm minima and maxima were 10.1-11.6, 6.8-9.0, 6.0-15.7, 8.2-14.1 and 0.0-10.4 mm for the semimembranosis, semitendonosus, gracilis, sartorius and popliteus, and 14.7-27.9 and 18.5-31.5 mm for the biceps femoris short and long, respectively. Moment arms for the ACL-deficient condition were significantly changed only at extremes of flexion-extension.

Three-dimensional kinematic analysis of the second through fifth carpometacarpal joints

The kinematics of the 2nd through 5th carpometacarpal (CMC) joints was investigated by using a 3-dimensional dynamic motion analysis system to delineate flexion-extension motion, radial-ulnar deviation, and pronation-supination motion. Analysis of the axes of rotation revealed that the axes of rotation for flexion-extension motion are located within the base of each respective metacarpal bone. The axis of rotation for radial-ulnar deviation passes through the distal carpal bone of each CMC joint except in the 3rd CMC joint where the axis of rotation is located within the base of the 3rd metacarpal. The axis of rotation for pronation-supination motion passes through the base of the respective metacarpal except in the 3rd CMC joint where it is located within the hamate. The overall flexion-extension motions of the 2nd and 3rd carpometacarpal (CMC) joints were found to be more limited than those of the 4th and 5th CMC joints (11 degrees, 7 degrees to 20 degrees, 27 degrees, respectively) and even more so in radial-ulnar deviation (2 degrees, 4 degrees to 7 degrees, 13 degrees, respectively) and pronation-supination motion (5 degrees, 5 degrees to 27 degrees, 22 degrees, respectively). The 5th CMC joint has the greatest overall range of motion with the flexion-extension motion found to be greatly reduced by 40% to 28 degrees when the 4th CMC joint was immobilized. Maximum range of motion in flexion-extension of the 5th CMC joint is dependent on and contributed by the 4th CMC joint motion.

The ligament and skeletal anatomy of the second through fifth carpometacarpal joints and adjacent structures

A detailed and comprehensive study of the anatomy of the 2nd through 5th carpometacarpal (CMC) joints and adjacent structures and clinical relevance is reported. Multiple dorsal ligaments were identified, including 2 from the 5th metacarpal (MC), 2 from the 4th, 3 from the 3rd, and 2 from the 2nd. There were also multiple volar ligaments, 1 from the 5th MC, 1 from the 4th, 4 from the 3rd, and 1 from the 2nd. There was only 1 intra-articular ligament, which was located between the 3rd/4th MC and the capitate/hamate and provided stability even when the dorsal and volar CMC ligaments were cut. There was more variability and often multiple distinct joint surfaces or facets forming the articulations between adjacent MCs and/or adjacent distal carpal bones. The joint surfaces between the 4th MC and the capitate and/or the hamate were also variable and had 5 different types of articulation. The area of the 2nd and 3rd CMC joints was found to have the highest incidence (18%) of carpal coalition, and when present there was a dorsal bone prominence and an absence of the normal dorsal ligament anatomy.

Material properties of Thera-Band Tubing

BACKGROUND AND PURPOSE

Thera-Band Tubing has been used in rehabilitation to provide resistance for exercise and splinting. However, the forces required to stretch the tubing have not been thoroughly quantified. Therefore, the therapist cannot assess, with certainty, how much force is applied when using a given length and type of Thera-Band Tubing. The purpose of this study was to quantify the material properties of Thera-Band Tubing.

METHODS

Force versus percentage of strain for all types of Thera-Band Tubing was measured during elongation in a mechanical testing machine.

RESULTS

The material is very compliant and displays nonlinear behavior in the initial stretching phase and linear behavior after 50% elongation.

DISCUSSION AND CONCLUSION

From the data obtained in this project, plots that can provide the therapist with information about the forces needed for exercises with Thera-Band Tubing were generated. These data should allow therapists to make better choices about which size of tubing to use for each patient.

Type I versus type II lunates: Ligament anatomy and presence of arthrosis

One hundred-seventy embalmed cadaver wrists were dissected. The type of lunate (type I, no medial hamate facet; type II, medial hamate facet), the incidence and location of arthrosis (exposed subchondral bone) in the lunohamate joint, and the anatomic relationship of the volar triquetrocapitate (T-C) and the volar triquetrohamate (T-H) ligaments were identified and measured. The relationship between the T-C and T-H ligaments was classified into 3 types. In type A the T-C ligament was completely separate from the T-H ligament, in type B the T-C ligament overlapped the T-H ligament, and in type C the T-C ligament had an additional ligament from the triquetrum to the proximal pole of the hamate. Eighty-two percent of type I lunates were associated with a type A relationship between the T-C and the T-H ligaments and 96% of type II lunates were associated with a type C relationship between the T-C and the T-H ligaments. Arthrosis at the proximal pole of the hamate was more commonly associated with the type II lunates (49%) and with the type C relationship (57%) of the T-C and T-H ligaments. The incidence of arthrosis in the lunohamate joint was also significantly greater in the type II lunate with a medial facet of 3 mm or more.

Kinematics of the wrist with a new dynamic external fixation device

The kinematic properties of a new dynamic external fixator device for treatment of distal radial fractures are described. Using a combination of data obtained from computed tomography scans and high-speed video images, a three-dimensional reconstruction of carpal motion was made. To describe carpal motion, the radiolunate, capitolunate, and scapholunate angles were measured during flexion and extension and during radioulnar deviation. During these types of motion, the device changed normal carpal kinematics to a limited extent although the differences in kinematic pattern with and without the device were small. The results for flexion and extension correspond with data from previously published studies with other dynamic external fixators. However, because the new device (Flexafix) allows flexion and extension and radioulnar deviation, in contrast to other dynamic external fixation devices, with its use normal carpal kinematics can be approached more closely.

Motion analysis in two dimensions of radial-ulnar deviation of type I versus type II lunates

The motions of 2 different types of lunate (type I, no medial hamate facet; type II, medial hamate facet) were evaluated and compared during radial-ulnar deviation of the wrist using radiography and magnetic resonance imaging. Ten right wrists (5 type I and 5 type II lunates) were studied using posteroanterior and lateral x-rays. Six of the 10 normal volunteers (3 type I and 3 type II lunates) were studied using magnetic resonance imaging in 6 positions of radial-ulnar deviation. In the radiographic study the ulnar shift ratio of the lunate (USR), the shortest distance between the proximal ulnar tip of the lunate and the distal ulnar edge of the sigmoid notch of the radius (R-L), the closest distance between the distal ulnar tip of the lunate and the proximal pole of the hamate (L-H), the radius of curvature of the proximal head of the capitate (Cr) on posteroanterior view, and the radiolunate angle on lateral view were measured in each wrist in each of the 6 positions. There were statistically significant differences between type I and II lunates with regard to average maximum ulnar deviation of USR and R-L, total change of USR, R-L distance and L-H distance, average L-H distance and Cr distance in all positions, and average radiolunate angle in neutral and 15 degrees ulnar deviation. In the magnetic resonance imaging study the wrists with a type I lunate did not have contact between the lunate and hamate in any position; the wrists with a type II lunate did have contact between the hamate and the lunate, but only in ulnar deviation. The results of this study demonstrate that the kinematics of a type I lunate are different from those of a type II lunate during radial-ulnar deviation of the wrist.

The scaphotrapezio-trapezoidal joint. Part 1: An anatomic and radiographic study

To evaluate anatomic variations and distribution of degenerative changes in the scaphotrapezio-trapezoidal (STT) joint, 165 embalmed cadaver wrists were examined. An interfacet ridge on the distal scaphoid was found in 81% of the wrists and the shape of the distal joint surface of the scaphoid was classified into 3 types. Underdevelopment of the capitate-trapezium ligament was found in 15% of the wrists. A new skeletal measurement for the inclination of the joint surface of the trapezium-trapezoid in the STT joint (TT inclination) was investigated anatomically and radiographically. Degenerative changes were found in 39% of the wrists. The most common location of degenerative changes was on its ulnar aspect on the distal scaphoid and on the radial and central aspect of the trapezoid on the TT side. The presence of degenerative changes had a significant correlation with a higher anatomic and/or radiographic TT inclination and/or underdevelopment of the capitate-trapezium ligament.

The scaphotrapezio-trapezoidal joint. Part 2: A kinematic study

Kinematics of the scaphotrapezio-trapezoidal joint during wrist flexion/extension motion (FEM) and radial/ulnar deviation (RUD) was investigated using a 3-dimensional dynamic motion analysis system. The scaphoid/trapezoid motion was found to be a rotational motion obliquely oriented relative to the sagittal plane of the wrist and described in an ulnoflexion/radial extension motion plane in both FEM and RUD of the wrist. The axis of rotation of the scaphoid/trapezoid motion during both FEM and RUD wrist motions was essentially the same and runs through the radiopalmar aspect of the distal scaphoid and the waist of the capitate. Motion analysis also revealed that the trapezium-trapezoid and trapezoid-capitate joints are essentially immobile. Hence, the scaphotrapezio-trapezoidal motion is considered to be a single degree of freedom that is essentially the same in both FEM and RUD of the wrist.

Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi)

Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2+/-0.1 l d(-1) and 123.0+/-6.8 ml kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na(+), K(+), and Cl(-) decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na(+):K(+) ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals.

Femoral surface strain in intact composite femurs: a custom computer analysis of the photoelastic coating technique

Understanding how forces are distributed through the proximal femur has many clinical applications for surgeons, researchers, and prosthetic designers. A new system for two-dimensional analysis of femoral surface strain was developed and applied to intact composite femurs. The photoelastic coating method was used to resolve the surface strain under axial loading, and strain analysis was performed using digital imaging of the strain patterns and original computer programs. The technique provides qualitative and quantitative data that describes overall femoral surface strains more completely than previous point analysis and strain gauge techniques. Results from repeated testing found the photoelastic process, computer imaging and computer analysis of strain areas to be statistically repeatable.

Scaphoid nonunions: a 3-dimensional analysis of patterns of deformity

We tested the hypothesis that the fracture location of scaphoid nonunions relates to the fracture displacement, development of dorsal intercalated segment instability (DISI) deformity, and changes in the contact area of the bones in the radiocarpal joint. Eleven patients with scaphoid nonunions were examined with 3-dimensional computed tomography and a new method of proximity mapping. Two different patterns of displacement of scaphoid nonunions were demonstrated, 1 volar and 1 dorsal. All patients with a volar pattern scaphoid nonunion had a DISI deformity. Only a few of the patients with a dorsal pattern scaphoid nonunion, mostly in longstanding nonunions, had a DISI deformity. The fracture line was generally distal to the dorsal apex of the ridge of the scaphoid in the volar-type fractures and proximal in the dorsal displaced fractures. The proximity map of the distal fragment of the scaphoid on the radius in the volar type shifts radial compared with normal; in the distal type it shifts dorsal. Neither of the patterns showed any significant changes of the proximity map in the radiocarpal joint at the proximal scaphoid fragment and the lunate. Whether the fracture line passes distal or proximal to the dorsal apex of the ridge of the scaphoid appears to determine the likelihood of subsequent fracture displacement, DISI deformity, and contact area of the bones in the radiocarpal joint.

Radiographic-anatomic correlation at different wrist articulations

The radiographs of 52 fresh cadaveric wrists were reviewed to assess their reliability in predicting the presence or absence of degenerative changes at the radiocarpal, midcarpal, and carpometacarpal joints. Direct comparison with anatomic dissection showed that except for the radioscaphoid articulation, there were no other sites with significant correlation between the radiographic and anatomic findings. We conclude that plain radiographs are not totally reliable for assessing changes of degenerative joint disease in the wrist.

The dorsal ligaments of the wrist: anatomy, mechanical properties, and function

The purpose of this study was to examine the anatomy and mechanical properties of the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments of the wrist and to better understand the functional design of the dorsal ligaments. The DRC ligament was consistently found to originate from the dorsal margin of the distal radius and extended ulnar obliquely and distally. Its radial fibers attached to the lunate and lunotriquetral interosseous ligament. The DRC ligament then inserted onto the dorsal tubercle of the triquetrum. The DIC ligament originated from the triquetrum and extended radially and attached onto the lunate, inserted into the dorsal groove of the scaphoid, and then extended to the trapezium. The DRC and DIC ligaments together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length by changing the angle between the 2 arms of the V. The DRC-DIC ligaments' lateral V configuration allows normal carpal kinematics while maintaining its indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist.

Anatomic study of the pisotriquetral joint: ligament anatomy and cartilagenous change

Eighty embalmed cadaver wrists (40 right and 40 left, 55 male and 25 female, aged 36 to 93 years [average age, 72.5 years]) were dissected to assess the anatomy of the pisotriquetral joint and the location of degenerative changes. The patterns of degenerative changes were classified into five types: type 1, central (8.8%); type 2, peripheral (38.8%); type 3, fan-shaped (13.8%); type 4, mixed (combination of > or =1 of types 1, 2, and/or 3; 10.0%); and type 5, total (12.5%). There was no cartilagenous change in 16.2% of the pisoform and 13.7% of the triquetrum. Degenerative changes (exposed subchondral bone and chondromalacia) on the articular surface of the pisiform were present in 83.3% of the wrists and on the triquetrum in 86.3% of the wrists. Degenerative changes were most commonly of the type 2 pattern (peripheral), with change located most commonly in the distal, distal-radial, and radial aspects of the pisiform and triquetrum. The ligamentous anatomy was categorized into 3 different types: type A, pisohamate and pisometacarpal ligaments inserted on the palmar distal aspect of the pisiform (52.5%); type B, pisohamate ligament inserted on the radial side of the pisiform and pisometacarpal ligament inserted on the palmar side of the pisiform (41.3%); and type C, type B anatomy with an additional ligamentous slip between the pisometacarpal ligament and the distal aspect of the hook of the hamate (6.2%).

High-speed, three-dimensional kinematic analysis of the normal wrist

Carpal kinematics during a wrist flexion/extension motion using high-speed videodata acquisition was investigated. A cadaver forearm was stabilized, allowing unconstrained excursion of the wrist for passive range of motion (ROM). The extensor and flexor pairs of the wrist were looped together and a 1-lb weight was attached to each pair, simulating synergistic muscle tension. Capitate/radius and third metacarpal/radius angles were calculated to determine which measurement would be best for determining global wrist angle. The average difference in capitate/radius and third metacarpal/radius angles at each respective flexion/extension wrist angle for all wrists was 1.1 degrees +/- 1.6 degrees (the maximum difference was 4 degrees). Hence, the capitate-third metacarpal joint can be considered rigid. Capitate/lunate motion as described by capitate-radius Euler angles ranged from -16.9 to 23.5 with total capitate/lunate motion of 40.5 (35%) in the 114 degrees total global wrist ROM measured. Radius/lunate motion as described by lunate-radius angle ranged from -8.2 to 48.4 with total radius/lunate motion of 56.5 (49%) in the 114 degrees total global wrist ROM measured. During global wrist motion, the radiolunate joint contributes more motion in flexion than the capitolunate joint and the capitolunate joint contributes more motion in extension than the radiolunate joint. The instantaneous screw axes (ISAs) were calculated for each third metacarpal position with respect to the radius. The average distance difference between ISAs for the 4 wrists tested was -1.23 +/- 14.97 pixels. The maximum distance was 56.51 pixels and the minimum was -24.09 pixels. This new combination of motion analysis and 3-dimensional reconstructions of computed tomography images affords a high-speed, dynamic analysis of kinematics. It shows that during wrist flexion/extension, normal carpal kinematics does not have an ISA fixed in or limited to the capitate. In addition, the ISA data provide evidence that translational motion is a real and measurable component of normal carpal motion. These findings alter the understanding of carpal kinematics obtained from the results of previous studies which suggested that the center of rotation was fixed in the capitate.

Muscle balance at the knee--moment arms for the normal knee and the ACL-minus knee

Forces, moments and stresses at the knee are dependent upon external and internal loading factors including muscle forces, segmental position and velocity, load carried, and the moment arms (mechanical advantage) of the muscle-tendon units. Requisite to prediction of forces and moments is a detailed understanding of effective moment arms throughout the knee range-of-motion (ROM). Existing muscle models for the knee are based upon limited static studies of only a few preserved specimens. The objectives of this report are to develop a comprehensive description of muscle-tendon moment arms for the normal knee and the anterior cruciate ligament (ACL)-minus knee during flexion-extension motion. Recent research results describe two nonorthogonal, nonintersecting axes of motion for the knee--one describing flexion-extension (FE) and the other longitudinal rotation (LR, equivalent to internal-external rotation). The effective flexion-extension moment arms of the muscles crossing the knee were developed with respect to the FE axis in 15 fresh, hemi-pelvis cadaver specimens. The normal moment arms for each of 13 muscles plus the patellar tendon exhibited variable, yet repeatable and recognizable patterns throughout the ROM. For most muscles there was no significant difference between the normal and ACL-minus moment arms. The results provide a basis for more accurate predictions of joint reaction forces and moments as well as useful knowledge for practitioners and therapists to assist in the assessment of muscle balance at the knee following injury, repair, and throughout rehabilitation.

Induction of novel Grp75 isoforms by 2-deoxyglucose in human and murine fibroblasts

Grp75 is a stress-inducible mitochondrial chaperone which has a high homology to senescence-related protein, p66mot mortalin. In human cells the mortalin gene assigns to the locus of a putative tumor suppressor gene for myeloid malignancies. In order to study expression and localization of Grp75 and p66mot in human and murine fibroblast lines, polyclonal antibodies were raised to conserved portions of each sequence. HT1080 and C3H10T1/2 cells were treated with various Grp-inducing agents. A single 75 kDa band was detected by Western blot of cytoplasmic proteins which was not greatly altered after thermal stress or treatment with L-azetidine-2-carboxylic acid or nonactin. However, glucose deprivation by 2-deoxyglucose treatment induced five novel isoforms at 74-75 kDa mass. Mortalin at 66 kDa could not be detected under these treatment conditions.

Normal wrist kinematics and the analysis of the effect of various dynamic external fixators for treatment of distal radius fractures

The purpose of this study was to evaluate the effect that external fixation devices used for distal radius fractures have on normal carpal kinematics, using high speed video data acquisition. Cadaver forearms were stabilized, allowing free excursion of the wrist for passive range of motion. Synergistic muscle tension was simulated by looping the extensor and flexor pairs of the wrist. Global wrist flexion and extension, intercarpal angles, and the instantaneous screw axis (ISA) were studied. These parameters allowed a quantification of normal carpal kinematics and comparison to the kinematics of the carpal bones with external fixators attached. This study shows that normal carpal kinematics during wrist flexion and extension do not have an ISA fixed in or limited to the capitate. In addition, the ISA data provide evidence that translational motion is a real and measurable component of normal carpal motion. This would change the understanding of carpal kinematics in previous studies that suggested that the center of rotation was fixed in the capitate. The proximal carpal (radiolunate) joint contributes more motion (has a greater rotation angle) in normal global wrist flexion and the midcarpal (capitolunate) joint contributes more motion in normal global wrist extension. In addition, the global range of motion and intercarpal joint angle of the wrist are limited with the application of any of the external fixators tested. None of the external fixators allowed normal ISA vector surfaces during wrist motion.

Load mechanics of the wrist

During the last decade, we have been studying load mechanics under a variety of conditions using pressure-sensitive film and, more recently, three-dimensional reconstructions and motion analysis. In all of these studies using pressure-sensitive film, the simulated pathologic or traumatic conditions that were tested showed that all areas in which an increase in contact area or pressure occurred, localized to one area of one joint, coincided with areas in which degenerative changes occurred in the simulated clinical situation. The areas in which there was a decrease or no change in contact area or pressure coincided with areas that were spared from degenerative changes in simulated clinical situations. More recent work has demonstrated that normal carpal kinematics during wrist flexion and extension do not have an instantaneous screw axis that is fixed in or limited to the capitate. These findings change the understanding previously based on studies suggesting that the center of rotation was fixed in the capitate. It was noted that during global wrist motion the radiolunate joint contributes more motion and flexion than the capitolunate joint, but the capitolunate joint contributes more motion and extension than the radiolunate joint. It also was demonstrated that translational motion is a normal component of carpal kinematics.

Tumor suppressor p53 gene forms multiple isoforms: evidence for single locus origin and cytoplasmic complex formation with heat shock proteins

The tumor suppressor protein p53 is a major cell cycle control factor, and mutations in p53 are the most common genetic lesion found in human tumors, resulting in loss of function and contributing to malignant transformation. This report reviews several studies which show that p53 protein appears as at least eleven isoforms having the same amino acid backbone but varying in charge by level of phosphorylation. All isoforms are derived from a single locus, which indicates that p53 activity is modulated by post-translational modification. In addition, mutant p53 forms hetero-oligomers with two families of proteins: HSP70 and a 90 kDa group similar to HSP90. Cytoplasmic complexes are most likely formed to protect p53 from proteolysis and are probably involved in translocation of activated p53 from the cytoplasm to the nucleus for transactivation of other cell cycle control genes.

HSP binding and mitochondrial localization of p53 protein in human HT1080 and mouse C3H10T1/2 cell lines

In normal cells, the tumor suppressor actions of p53 protein are mediated by specific DNA binding and protein-protein interactions within the nucleus. Mutant p53 proteins, however, often assume an aberrant conformation devoid of tumor suppressor activity and newly capable of binding to the cognate or inducible HSP70. Recent reports from our laboratory and others show that additional unknown proteins may also complex with mutant p53. In this study, we characterize p53:HSP complexes and their subcellular location in the transformed cell lines, human HT1080 and murine C3H10T1/2, which both contain aberrant p53 conformers. Immunoprecipitation and SDS-PAGE of p53 from whole cell lysates revealed the additional presence of a broad 70 kDa band and a 90 kDa band in both lines, while p53 isolated from nuclear lysates was free from other proteins. 2D-PAGE was used to isolate and identify HSP members from cytoplasmic and nuclear lysates by immunoprecipitation, Western blotting and protein sequencing. Anti-p53 immune complexes from cytoplasmic lysates contained not only HSC70 but also GRP75, GRP78 and a weakly basic 90 kDa protein, which may be related to HSP90. The inducible form of HSP70 was not complexed to p53 protein, even though expressed in these cells. Analysis of anti-HSP70, anti-GRP75 and anti-HSP90 immune complexes suggests that HSP members exist as performed complexes in the cytoplasm, but not the nucleus. The presence of the mitochondrial and endoplasmic reticular chaperones, GRP75 and GRP78, in p53:HSP complexes suggested that p53 might be found in these cytoplasmic organelles which was confirmed in mitochondria by biochemical and immunoelectron microscopic evidence. These studies suggest that newly identified members of p53:HSP complexes represent components of a chaperone program which affects the subcellular distribution of p53 protein in these transformed lines.

Variability and consistency of electric and magnetic field occupational exposure measurements

There is widespread scientific and public interest in possible health effects from exposure to electric and magnetic fields at frequencies associated with electricity use. Electric and magnetic field exposure assessment presents specific problems, among which are the inherent variability in exposure, the lack of robust statistical summary measures, and the lack of an accepted metric based on biological response. These pose challenges in defining distinct exposure groups, a basic goal for exposure assessments used in epidemiological studies. This paper explores the extent to which distinct electric and magnetic field exposure groups can be defined, by examining the variability and consistency of occupational electric and magnetic field exposure measurements among studies and within individual studies. Principal analyses are made by job titles because they are the most frequently used descriptors for stratifying occupational exposures to electric and magnetic fields. Methodological issues affecting the degree of consistency in measured electric and magnetic field exposures among occupational environments are also examined. Exposures by job title reported from electric and magnetic field measurement studies are summarized by general job category and industry. Analyses are performed both within and between job categories. Distributions of daily measured exposures for job categories taken from three large studies in the U.S. electric utility industry are compared to investigate consistency of exposures at a more detailed level. Analyses of reported personal exposure measurements from many studies and countries are consistent with less rigorous observations made heretofore on the basis of individual studies. In these studies, significantly elevated electric and magnetic field exposures are found in the electrician, lineworker, and substation worker categories; significantly elevated magnetic field exposures are also noted in the generation worker category; and magnetic field exposures in these groups are consistent across countries. Analyses within and among the elevated exposure job categories indicate that there are no significant differences between them. Among the studies, it is not possible to distinguish between exposures for well-defined groups within the categories, such as between transmission lineworkers and distribution lineworkers in the lineworker category; between generation operators and generation mechanics; or between substation operators and substation maintenance workers. This information provides a context for past studies and will help future efforts to define distinct occupational exposure groups exposed to electric and magnetic fields. Compilations of measured personal exposure data by industry and job title have been prepared as appendices (available from the author upon request).

Human p53 expressed in baculovirus-infected Sf9 cells displays a two-dimensional isoform pattern identical to wild-type p53 from human cells

Baculovirus expression of human p53 protein, a nuclear cell cycle regulator, was examined in Sf9 cells and compared to native p53 synthesized in primary human cells. Maximum expression of the recombinant p53 protein occurred 48 h postinfection. De novo synthesis of the protein was evident for only 2 days postinfection; however, in pulse-chase studies, 30% of the synthesized protein remained stable up to 5 days. Seventy-seven percent of immunoprecipitated, [35S]-methionine-labeled, recombinant p53 protein resided in the cytoplasm of Sf9 cells, while 15% localized to the nucleus and 8% was released extracellularly. Separation of modified p53 protein, by charge and molecular weight, was accomplished by two-dimensional PAGE, and the electrophoretic pattern of the recombinant protein was identical to the wild-type protein from primary human mammary epithelial cells, indicating that the posttranslational modifications of the recombinant protein in this system are similar to those in primary human cells. Eleven isoforms focused between pI 5.75 and pI 6.5. The recombinant p53 isoforms were phosphorylated by 32P-labeling. Phosphatase digestion of immunoprecipitated p53 effectively removed phosphorous groups from the recombinant protein, reducing the number of isoforms from 11 to 2, demonstrating that phosphorylation is the major posttranslational event in the recombinant protein.

Carpal bone anatomy measured by computer analysis of three-dimensional reconstructions of computed tomography images

Using quantitative analysis of three-dimensional reconstructions of computed tomography scan data, a normative database of carpal bone morphology was built. Thirty-five wrists were imaged in a computed tomography scanner. Each slice was processed to determine the bone edges and assembled as a three-dimensional model by stacking. Quantitative measurements of volume, surface area, maximum length, and intercarpal distances were then assessed. A reliable three-dimensional carpal height ratio was calculated by dividing the carpal height (minimum distance between the fourth metacarpal and the radius) by the capitate maximum length. For volume, maximum length, and surface area, the order for the eight carpal bones with respect to size (in descending order) were: capitate, hamate, scaphoid, trapezium, lunate, trapezoid, triquetrum, and pisiform. Male wrists were significantly larger than female wrists. There were no significant differences in the relative dimensions between left and right wrists, or between left and right wrists of matched pairs. This technology offers automated analysis of three-dimensional geometric carpal information and the opportunity to obtain a body of information about normal and abnormal morphology as well as spatial relationships between carpal bones.

Baculovirus and insect cell gene expression: review of baculovirus biotechnology

The BEVS continues to evolve as a powerful, flexible tool for molecular biology, protein function, and biomedical research. Future developments offer the promise of replacement of hazardous chemical insecticides with environmentally safe biopesticides, construction of baculovirus vectors which encode genes for specific post-translational modifications, and establishment of efficient, stably transformed insect cell lines. FDA approval of BEVS-produced products offer the prospect of new biopharmaceuticals, in particular human therapeutics and vaccines, to improve human health and increase the quality of life for millions of people.

Extrinsic wrist ligaments in the pathomechanics of ulnar translation instability

A description of the various combinations of ligament disruptions necessary for ulnar translation instability is presented based on a series of cadaver dissections and load studies. Dissections and load studies demonstrated that major ligament disruption, even to the extent that only the dorsal ulnolunate, the palmar ulnolunate or the radioscaphocapitate, and the long radiolunate ligaments were left intact, failed to result in meaningful ulnar translation of the carpus. The radioscaphocapitate ligament alone could not prevent significant ulnar translation. Palmar translation instability was evident with less ligament disruption than that needed for ulnar translation and was always evident if there was ulnar translation. These studies imply that ulnar translation represents a much more global ligament disruption and instability than previously suggested in the literature.

Phosphor image analysis of human p53 protein isoforms

Phosphor imaging was evaluated for detection, quantitation and resolution of multiphosphorylated protein isoforms separated by two-dimensional gel electrophoresis. A nuclear phosphoprotein, p53, was isolated by immunoprecipitation after biosynthetic labeling with 35S, 32P or 33P in cultured human cells. Of the three radionuclides, 35S was the most sensitive in detection after a 1-week exposure, although shorter exposure times were effective. In dividing cells, 11 35S-labeled isoforms were found, of which 10 were phosphorylated by 33P and 32P. Exposure of phosphonuclides for one half-life showed that 33P radiolabeling produced better resolution among isoforms than 32P but was less sensitive in detection. Volume integration showed phosphorylated isoforms comprised from 1% to 25% of total isoform signal. The relative phosphorylation of each p53 isoform was estimated by normalizing 33P or 32P isoform volumes with the corresponding 35S volume and showed progressive phosphorylation of acidic isoforms. Additionally, phosphor imaging capably detected quantitative changes among individual isoforms after experimental modulation of the isoform pattern by serum deprivation. The described electrophoretic isolation and quantitation procedures should find general application in discerning active and inactive phosphoisoforms for eventual identification.

A comparison of double-plate fixation methods for complex distal humerus fractures

A modified method of fracture fixation of complex distal humeral fractures with medial and lateral plates and bolts was biomechanically tested and compared with previously described fixation techniques. Compressive stiffness coefficients were determined for three classes of fixation before and after fatigue cycling. This procedure was followed with compressive loading to failure. The results show that in the most unstable fracture type tested this new fixation method provides increased strength and stability. Early clinical follow-up examinations of patients treated with this technique show that this method is a reasonable fixation alternative for the complex distal humerus intercondylar fracture.

Altered protein synthesis in p53 null and hemizygous transgenic mouse embryonic fibroblasts

Embryonic fibroblasts derived from p53-deficient transgenic mice showed distinct phenotypic and biological changes in vitro. In this study, we investigated the possible impact of p53 on the synthesis of other cellular proteins by comparing the protein profiles of p53 null (-/-), hemizygous (+/-) and p53 positive homozygous (+/+) cells using high resolution two dimensional gel electrophoresis. A total of more than 850 proteins were detected in each cell line labeled with 35S-methionine by using computerized image analysis, and a number of proteins were detected with qualitative or quantitative changes in p53-/- cells and to a lesser extent in p53+/- cells. Specifically, seven proteins became undetectable, and no new proteins were detected in p53-/- cells. Neither newly expressed nor absent proteins were detected in p53+/- cell line. Quantitatively, a total of 97 and 59 proteins were detected with significant quantitative changes (3 fold or greater) in p53-/- and p53+/- cells, respectively. Generally, most protein changes fell into one of the following four patterns: 1) progressively decreased synthesis in cells from p53+/+ to p53+/- to p53-/- cells; 2) progressively increased synthesis in cells from p53+/+ to p53+/- to p53-/- cells; 3) decreased synthesis only in p53-/- cells; and 4) increased synthesis only in p53-/- cells. A 70 kD heat shock protein (Hsp 70) was identified and showed a greater than 1,000-fold increase in p53-/- cells compared to that in p53+/+ cells. Transferrin, tropomyosin, and proliferating cell nuclear antigen (PCNA) have also been identified and measured in this study. Synthesis of transferrin and tropomyosin was significantly increased or decreased, respectively in p53-/- cells, whereas expression of PCNA showed no significant change in p53-/- cells despite their much higher (3-4 times) proliferation rate than the other two cell lines (p53+/+ and p53+/- cells). We conclude that disruption of a single important gene, p53, results in a cascade of protein changes which are related to the loss of p53 mediated negative growth effects on cell cycle control.

Quantification of anatomic, geometric, and load transfer characteristics of the wrist joint

The work reported here is an assimilation of 8 years of research, the purpose of which was to gain a better understanding of the normal and abnormal workings of the wrist joint. The results are summarized in three major areas of concentration: descriptive anatomic studies, which include direct measurements of cadaver specimens, biomechanical loading studies to define load distribution through normal and abnormal wrists, and three-dimensional (3D) anatomy studies using solid models derived from computed tomographic (CT) images of in vivo and cadaver wrists. The descriptive anatomic studies used 393 cadaver wrists to evaluate the incidence and distribution of anatomic features, arthroses, chondromalacia, and soft-tissue lesions. The data were analyzed for any statistically significant associations among different variables. The biomechanical studies characterized the biomechanics of the human wrist in a variety of normal, simulated traumatic, and surgically treated conditions. The results of the load studies have provided clinically relevant information on the normal anatomy and functional mechanics of the wrist as well as guidelines for the treatment of a number of different fractures and ligament injuries. The 3D anatomic studies use quantitative analysis of 3D reconstructions of CT scan data to build a normative database of carpal bone morphology. Thirty-five wrists were imaged in a CT scanner. Quantitative measurements of volume, surface area, maximum length, and intercarpal distances were than assessed. A reliable 3D carpal height ratio (3DCHR) was calculated by dividing the capitate maximum length by the carpal height, which is the minimum distance between the fourth metacarpal and the radius.

Deletion 5q35.3

We report on a 15-month-old boy with a de novo deletion of the terminal band of 5q, macrocephaly, mild retrognathia, anteverted nares with low flat nasal bridge, telecanthus, minor earlobe anomalies, bell-shaped chest, diastasis recti, short fingers, and mild developmental delay.

Separation and sequencing of familiar and novel murine proteins using preparative two-dimensional gel electrophoresis

Strategies are needed for rapid protein isolation in order to identify disease-related proteins and facilitate the design of oligonucleotides for further molecular inquiry. In our laboratory, C3H10T1/2 murine fibroblasts have been found to express a variety of proteins in various subcellular fractions which are relevant to experimental transformation and carcinogenesis. Preparative two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) procedures were developed to identify major cytoplasmic proteins by electroblotting and microsequencing. Isoelectric focusing tube gels were enlarged to 6 mm ID to accommodate larger protein loads at 0.5 to 2 mg protein. Separated proteins were electrotransferred from 6 mm thick slab gels onto 0.22 mu polyvinylidene difluoride membranes. Nearly 100 prominent blotted proteins were stained with Coomassie Brilliant Blue between pI 4.5-7.0 and 18-106 kDa and, of these, 27 prominent and well-resolved proteins were selected for sequencing. Sequences of 14 to 24 amino acid residues in length were obtained from 11 proteins which were identified from computerized databases. Some of these identified proteins had structural or enzymatic functions while others had only recently been discovered, including a newly reported Hsp 70 class member and a novel calcium-binding protein, reticulocalbin. The new heat shock protein has a molecular mass of 75 kDa and has been designated as Grp75, PBP74, CSA or p66mot-1 in mice and humans with purported roles in transformation and antigen processing. Reticulocalbin is an endoplasmic reticular protein which contains six domains of the EF-hand motif associated with high-affinity calcium-binding proteins. It may be involved in protein transport and luminal protein processing. In addition, sequences of 5 to 11 residues in length were also obtained from six other unidentified proteins. Thus, we have found that preparative 2-D PAGE serves as a powerful one-step purification method for protein isolation and characterization from an important in vitro murine model for the study of carcinogenesis.

Phenotypic change and altered protein expression in X-ray and methylcholanthrene-transformed C3H10T1/2 fibroblasts

The morphology, growth properties and cellular protein patterns from parent and two transformed C3H10T1/2 cell lines were analyzed to associate the phenotypic and protein differences with cell transformation. Transformed 10T1/2 cells were obtained by colony isolation after exposure of parent 10T1/2 cells to methylcholanthrene (MCA-1 cell line) or X-ray irradiation (XR-III cell line). Compared to parent 10T1/2 and MCA-1 cells, XR-III cells were much smaller in size and exhibited the highest growth rate, greatest cell saturation density, increased plating efficiency and greater expression of proliferating cell nuclear antigen. MCA-1 cells showed intermediate characteristics between parent and XR-III cells. Among the three cell lines, only XR-III cells showed anchorage-independent growth in soft agar. When [35S]methionine-labeled whole cell lysate proteins were separated by two-dimensional polyacrylamide gel electrophoresis, computer comparison algorithms revealed a 97% similarity in protein profiles among almost 800 proteins detected from each cell line. However, comparison of proteins patterns of the transformed cell lines to that of parent 10T1/2 cells showed that 30 and 20 proteins were induced or repressed in XR-III cells and MCA-1 cells, respectively. Similarly, 81 and 24 proteins showed significant quantitative changes (threefold or greater) in XR-III and MCA-1 cells, respectively, as compared with parent 10T1/2 cell proteins. The anchorage-independent growth and increased proliferation properties of XR-III cells suggest a later stage of transformation compared to MCA-1 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Location and geometric description of carpal bones in CT images

The carpal regions of ten cadaver extremities were imaged by CT. The images were combined into a 3-dimensional model of the carpus using a technique based on a dynamic programming algorithm to find an optimal estimate of the location of the bone boundaries in the CT images. The resulting set of surface points on each bone was used to compute volumes and principal and antipodal axes for the bones. A spatial coordinate system was established based on the positions of the centroids of three bones in the distal carpal row. The angular orientations of all carpal bones were determined with respect to this system. The principal axes for the same bone among ten wrist specimens proved to be more widely dispersed than the antipodal axes for the same bones. The antipodal axes also correspond more closely to an intuitive notion of the "longest axis" of the bones. We conclude that the antipodal axis is a more reliable and useful measure of bone orientation than the principal axis.

DNA confirmation of congenital myotonic dystrophy in non-immune hydrops fetalis

We report on the prenatal diagnosis of congenital myotonic dystrophy in a case of non-immune hydrops fetalis. DNA analysis of amniocytes revealed expansion of the trinucleotide (CTG) repeat within the myotonin PK gene, associated with myotonic dystrophy. The fetus was found to have approximately 1730 copies, while the normal population has between 5 and 27 copies, and minimally affected individuals have at least 50 copies.

Wrist anatomy: incidence, distribution, and correlation of anatomic variations, tears, and arthrosis

We dissected 393 wrists to evaluate the incidence and distribution of anatomic features, arthrosis, chondromalacia, and soft tissue lesions. The data were then analyzed for any statistically significant associations among the different variables. The most common (73%) lunate morphology had a separate medial facet on its distal surface for the hamate. The capitate had a separate facet for the fourth metacarpal in 86% of the wrists. Fourth metacarpals with a dorsal radial facet, either separate from or connected to the rest of the fourth metacarpal base, were the most common types of fourth metacarpal. Cartilage erosion with exposed subchondral bone was identified in 58% of the wrists. It was most commonly at the proximal pole of the hamate (28%). Tears of the ligaments and/or the triangular fibrocartilage complex were identified in 56% of the wrists. The triangular fibrocartilage complex was found torn in 36% of the wrists. The lunotriquetral interosseous ligament was torn in 36% of the wrists, and the scapholunate interosseous ligament was torn in 28% of the wrists. There was a communication between the proximal wrist joint and the pisotriquetral joint in 88% of the 76 wrists, which were further dissected to assess this issue. Statistical analysis of the data found a significant correlation between the presence of cartilage erosion at the proximal pole of the hamate and the presence of a lunate facet. There was also a significant correlation between the presence of a tear in the scapholunate interosseous ligament and the presence of cartilage erosion in the scaphoid-trapezium-trapezoid joint. Analysis of the paired wrists from 169 cadavers revealed that the same soft tissue tear or combination of tears was present bilaterally in 39% of the pairs. Cartilage erosion was present bilaterally in the same location or locations in 27% of the pairs.

Fetal growth: a comparison of growth curves with mathematical modeling

This study compared the use of fetal growth curves with the Rossavik mathematical model in predicting third trimester fetal growth in 27 Hispanic patients. The parameters tested were BPD, HC, AC, and FL. The growth curve method of predicting third trimester fetal growth was significantly more accurate than the mathematical model for three of the four fetal parameters tested: BPD, HC, and FL. We conclude that the mathematical model method offered no advantage over the more commonly used growth curve method for predicting third trimester fetal growth. In addition, growth curves do not require complex calculations and are conceptually simpler and easier to use.

Measurement of carpal bone geometry by computer analysis of three-dimensional CT images

The aim of this project was noninvasively to analyze and quantitate the geometry, load transfer characteristics, and spatial relationships of the carpal bones by using a new three-dimensional CT scan reconstruction technique. The determination of mechanical parameters such as distances between centroids and between bone surfaces, carpal alignment, volumes, surface areas, and contact areas can provide the basis for comparison between normal wrists and wrists with a variety of progressive instability patterns, types of fracture, pathologic and posttraumatic states, and different simulated surgical procedures. This new technology has demonstrated a volumetric accuracy of 94% and a linear accuracy of 97%. Simultaneous analysis of all articulating surfaces of multiple joints can be performed in cadavers and in patients because of the noninvasive nature of the imaging reconstruction technique. This new research offers much more information than has previously been available. It also promises direct application to the clinical setting and eliminates several limitations and questions that were inescapable with previous technology.

Load mechanics of the midcarpal joint

The midcarpal joint was studied in upper extremities of fresh cadavers with the use of a static positioning frame, pressure-sensitive film, and a microcomputer to analyze the contact prints. The contact area on the proximal side of the midcarpal joint was found to consist generally of four areas; the scaphoid-trapezium-trapezoid, the scaphoid-capitate, the lunate-capitate, and the triquetrum-hamate. The contact areas accounted for less than 40% of the available joint surface, even under loads of 118 pounds. The distribution of load through the midcarpal joint was scaphoid-trapezium-trapezoid 23%, scaphoid-capitate 28%, lunate-capitate 29%, and triquetrum-hamate 20%. The midcarpal joint, like the radiocarpal joint, appears to transmit load through distinct areas and through a relatively small portion of the available joint surface.

Simulated scaphoid proximal pole fracture

Five fresh cadaver upper extremities were studied with use of a static positioning frame, pressure-sensitive film, a microcomputer-based videodigitizing system, and a Sun station image analysis system to assess the load bearing characteristics of the scaphoid in the proximal carpal joint. Specimens were studied in their normal condition, after a proximal pole osteotomy of the scaphoid, and after resection of the proximal pole of the scaphoid. The amount of contact area born through the scaphoid fossa was essentially the same whether the scaphoid was intact, or after a simulated scaphoid fracture of its proximal pole, or after resection of the proximal pole. The scaphoid contact area and pressure, although overall relatively constant, was redistributed after osteotomy, resulting in increased contact area under the distal fragment and no change or a slight decrease in the contact area under the proximal fragment of the scaphoid. After resection of the proximal fragment, all scaphoid contact area and pressure was born by the distal scaphoid fragment. The contact area and pressure characteristics of the lunate remained unchanged in all conditions compared with the normal condition. There were no significant changes in the locations of the centroids of the scaphoid segments and the lunate in any of the conditions tested.

Comparison of cortical and cancellous screw pull-out strengths about the posterior column and sacroiliac joint

This study addresses the comparative pull-out strengths of cortical (4.5 mm) and fully threaded cancellous (6.5 mm) bone screws from sites about the pelvis commonly used in the fixation of posterior column acetabular fractures and sacroiliac (SI) disruptions. These sites include one from lateral to medial through the posterior column, two from posterolateral to anteromedial across the SI joint, one vertically through the sacral ala, and one vertically through the iliopubic column. Statistical analysis showed no significant difference in the force required for pull-out failure of the cortical versus the cancellous screws at any of the sites tested.

The silicone scaphoid: a biomechanical study

Five fresh cadaver upper extremities were studied by use of a static positioning frame, pressure-sensitive film, and a microcomputer-based videodigitizing system, to assess the load-bearing characteristics of a scaphoid silicone implant within the radioulnarcarpal joint. Specimens were studied in their "normal" condition, after resection of the scaphoid, after placement of a scaphoid implant, and with a scaphoid implant and a simulated capitate-lunate-triquetrum-hamate fusion. The scaphoid silicone implant bore significant, although less, load than the normal scaphoid. Decreasing the size of the scaphoid implant decreased the load born by the implant. Decreased load through the scaphoid implant was compensated by the lunate. The addition of a limited carpal fusion did not significantly decrease the load born by a scaphoid implant. Therefore, the silicone scaphoid implant is a load-bearing implant even when undersized or placed in association with a limited carpal fusion.

A prospective randomized comparison of oral terbutaline and magnesium oxide for the maintenance of tocolysis

We compared oral magnesium oxide with oral terbutaline sulfate in a prospective, randomized manner to determine efficacy and side effects. Preterm labor patients whose labor was arrested with parenteral tocolysis were randomized to oral tocolysis with either magnesium oxide, 200 mg every 3 to 4 hours (n = 23), or terbutaline, 2.5 to 5 mg every 3 to 4 hours (n = 27). The number of patients who were delivered of infants before 36 weeks' gestation was similar between groups (18.5% receiving terbutaline versus 17.4% receiving magnesium). At least one side effect occurred in 81.5% of patients in the terbutaline group and 47.8% in the magnesium group (p less than 0.01). Finally, the cost for 1 day of magnesium (20 cents) is approximately one third the cost of terbutaline (56 cents). These data suggest that oral magnesium oxide is as effective as terbutaline for the maintenance of tocolysis, with fewer side effects and at a lower cost.