An in vitro comparison of an adjustable bone fixation system.

PURPOSE: The purpose of this study was to biomechanically compare an adjustable plating system and several variations with an inverted-L pattern of 3 bicortical screws to fix a bilateral sagittal split osteotomy. MATERIALS AND METHODS: Sixty polyurethane mandible replicas (Synbone, Laudquart, Switzerland) were used in this study. Ten uncut mandibular replicas served as control models. Fifty experimental synthetic mandibles had bilateral sagittal split osteotomies created with a 7-mm advancement. Fixation modalities included 3 bicortical screws in an inverted-L pattern, a 4-hole sagittal split plate with adjustable slider (slide 0), an adjustable plate with an additional bicortical screw (slide 1), an adjustable plate with 2 additional bicortical screws (slide 2), and an adjustable plate with 3 additional bicortical screws (slide 3). The alloplastic mandibles were secured in a custom fabricated jig and subjected to vertical loads at the incisal edge and torsional loading at the molar region by an Instron 1331 (Instron, Canton, MA) servohydraulic mechanical testing unit. Mechanical deformation data within a 0- to 900-N range were recorded. Yield load, yield displacement, and stiffness were determined. Means and standard deviations were derived and compared for statistical significance using a Fisher's Protected Least Significant Differences Test with a confidence level of 95% (P < .05). Second-order best-fit polynomials were created for the experimental data curves. RESULTS: For incisal edge loading, the control was significantly greater for yield load than the experimental models. No significant difference was noted between slide 0, slide 1, and slide 2, but significant differences were seen with slide 3 and the inverted-L. There were no significant differences between slide 1, slide 2, slide 3, and inverted-L. For molar load, the control was significantly different than the experimental models. However, there was no significant difference between the experimental models. CONCLUSIONS: Mandibular advancements of 7 mm in a synthetic mandible fixed with a 4-hole sagittal split plate with adjustable slider alone is resistant to torsional forces and comparable to that seen with 3 bicortical screws placed in an inverted-L fashion. However, when loading at the incisal edge, additional bicortical screws are necessary to achieve the similar resistance to vertical load as that seen with 3 bicortical screws.

A biomechanical evaluation of bilateral sagittal ramus osteotomy fixation techniques.

OBJECTIVES: The purpose of this investigation was to evaluate and compare the biomechanical behavior of various rigid internal fixation plates designed to aid in the condylar positioning of bilateral sagittal ramus osteotomies, to positional screws in an inverted-L pattern, and a control. MATERIALS AND METHODS: Fifty polyurethane synthetic mandible replicas (Synbone, Laudquart, Switzerland) were used in this investigation. Five controls and 5 each of 4 different fixation modalities (3 bicortical positional screws in an inverted-L pattern, monocortical 4-hole straight plates, monocortical 6-hole curved plates, and monocortical adjustable 4-hole slide plates) were subjected to vertical loading at the incisal edge and torsional loading at the molar region by an Instron 1331 (Instron, Canton, MA) servohydraulic mechanical testing unit. Mechanical deformation data within a 0 to 900 N range were recorded. Yield load, yield displacement, and stiffness were determined. Means and standard deviations were derived and compared for statistical significance using a Fisher's Protected Least Significant Differences Test with a confidence level of 95% (P < .05). Second-order polynomial best-fit curves were also created for each group to further evaluate mechanical behavior. RESULTS: For incisal edge loading, statistically significant differences were noted between the control group and all other groups for yield load and stiffness, and between the control group and straight, curved, and slide plates for yield displacement. Differences were also noted between the inverted-L and straight, strut, and slide plates for yield load; and inverted-L and straight, curved, and slide, as well as straight and slide for yield displacement. For molar loading, statistically significant differences were noted between the control group and all other groups for yield load and stiffness. Differences were noted between the slide and straight, curved, and control; as well as between the inverted-L and straight and strut plates for yield displacement. Lastly, differences were noted between the straight and curved plates, and the slide and straight, curved, and inverted-L for stiffness. CONCLUSION: In this in vitro study, differences were noted between the control and all experimental groups in their abilities to resist loads under all of the conditions tested. Differences were also noted among specific experimental groups. Yet when placed in the context of functional parameters, only the bicortical positional screws in an inverted-L pattern met the requirements for both molar loading and incisal edge loading.

The relationship between enophthalmos, linear displacement, and volume change in experimentally recreated orbital fractures.

PURPOSE: The purpose of this investigation was to establish the relationship between enophthalmos, linear displacement, and volume change for various patterns of experimentally recreated orbital fractures. MATERIALS AND METHODS: We fabricated an experimental apparatus that permitted uniform displacement of simulated orbital wall fractures. Measurements of linear displacement, volume change, and degree of simulated enophthalmos were taken for 1- and 2-walled displacements. Means and standard deviations were derived, and analysis of variance was used to compare means for statistically significant differences ( P < .05) between groups and among major categories. RESULTS: No statistically significant differences were found for any uniform displacement caused by 1-walled defects or for any given displacement caused by 2-walled defects The linear coefficient for displacement and enophthalmos or for displacement and volume change approached 1.0 for all groups (range, 0.9802 to 0.9999). However, statistically significant differences in mean enophthalmos and mean volume change at uniform displacements were found between 1- and 2-walled defects. CONCLUSIONS: Displacement of 1- and 2-walled orbital defects results in a direct and linear change in both orbital volume and enophthalmos, regardless of the location of the defect.

A biomechanical evaluation of mandibular condyle fracture plating techniques.

OBJECTIVES: The purpose of this investigation was to evaluate the biomechanical behavior of various rigid internal fixation techniques for mandibular condylar process fractures. MATERIALS AND METHODS: Synthetic mandible replicas (Synbone, Landquart, Switzerland) were used to evaluate a control, and four monocortical mandibular condyle plating techniques. Each group was subjected to linear loading in lateral to medial, medial to lateral and posterior to anterior directions by an Instron 1331 (Instron, Canton, MA) servohydraulic mechanical testing unit. Yield load, yield displacement, and stiffness were measured. In addition, each group was subjected to torsional loading using an Instron 8521 (Instron). Yield torque, yield rotation, and stiffness were measured. Five samples were tested for each group and method of loading (n = 100). Means and standard deviations were derived and compared for statistical significance using a 1-way analysis variance (P <.05). Third-order polynomial best-fit curves were also created for each group to further evaluate and compare the mechanical behavior. RESULTS: Statistically significant differences were noted between fixation groups for the different mechanical measures evaluated under the different conditions of linear loading. Statistically significant differences were noted between groups for yield rotation during torsional loading. Although different in magnitude, similar patterns of mechanical behavior were observed in the third-order polynomial best-fit curves for lateral to medial loading, medial to lateral loading and torsional loading. For posterior to anterior loading, different patterns of mechanical behavior were noted between the experimental groups, but similar behavior was noted between the control and mini dynamic compression plate CONCLUSIONS: While differences were noted between each of the fixation systems in their abilities to resist loads under the conditions tested, the mini dynamic compression plate provided the most favorable mechanical behavior. Based on the presumed clinical parameters, we can suggest that none of the systems evaluated were ideal for the treatment of mandibular condyle fractures, but that the mini dynamic compression plate is the closest to an effective means for reconstruction.

One-year follow-up evaluation of the sexually transmitted diseases/human immunodeficiency virus intervention program in a marine corps sample.

Although a substantial number of studies have been conducted to evaluate the impact of various human immunodeficiency virus (HIV) prevention programs, most of them have focused on civilian populations. There is a clear need to develop and evaluate sexually transmitted diseases (STD)/HIV prevention programs designed specifically for U.S. military populations. The objective of the present study was to determine whether a behavioral intervention known as the STD/HIV Intervention Program (SHIP) would have a sustained positive impact on the behavior of a sample of Marines. A 1-year follow-up telephone interview was administered to (1) Marines who participated in the SHIP course (intervention group), and (2) a quasi-control group of Marines who were not exposed to the SHIP course. The intervention and control groups differed significantly in the percentage of the time they had used condoms during the past year. The intervention participants reported using condoms a greater percentage of the time than the nonparticipants.

Evaluation of a sexually transmitted disease/human immunodeficiency virus prevention train-the-trainer program.

In this study, a behavioral intervention known as the STD/HIV Intervention Program (SHIP) was implemented at the Navy preventive medicine technician (PMT) school as a "train-the-trainer" course. Course evaluation questionnaires were administered to PMT students immediately after the training. Follow-up interviews evaluating the SHIP course were conducted with PMTs (N = 73) 1 year after the training. PMT students were fairly satisfied with SHIP overall, as well as with specific components of the course. As hypothesized, the SHIP train-the-trainer course was considered useful by most PMTs in their first duty assignments after completing PMT school.

Phase II study of rituximab in combination with chop chemotherapy in patients with previously untreated, aggressive non-Hodgkin's lymphoma.

PURPOSE: To determine the safety and efficacy of the combination of the chimeric anti-CD20 antibody Rituxan (rituximab, IDEC-C2B8; Genentech Inc, South San Francisco, CA) and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy in patients with aggressive non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: Thirty-three patients with previously untreated advanced aggressive B-cell NHL received six infusions of Rituxan (375 mg/m2 per dose) on day 1 of each cycle in combination with six doses of CHOP chemotherapy given on day 3 of each cycle. RESULTS: The ORR by investigator assessment confirmed by the sponsor was 94% (31 of 33 patients). Twenty patients experienced a complete response (CR) (61%), 11 patients had a partial response (PR) (33%), and two patients were classified as having progressive disease. In the 18 patients with an International Prognostic Index (IPI) score > or = 2, the combination of Rituxan plus CHOP achieved an ORR of 89% and CR of 56%. The median duration of response and time to progression had not been reached after a median observation time of 26 months. Twenty-nine of 31 responding patients remained in remission during this follow-up period, including 15 of 16 patients with an IPI score > or = 2. The most frequent adverse events attributed to Rituxan were fever and chills, primarily during the first infusion. Rituxan did not seem to compromise the ability of patients to tolerate CHOP; all patients completed the entire six courses of the combination. The bcl-2 translocation of blood or bone marrow was positive at baseline in 13 patients; 11 patients had follow-up specimens obtained (eight CR, three PR), and all had a negative bcl-2 status after therapy. Only one patient has reconverted to bcl-2 positivity, and all patients remain in clinical remission. CONCLUSION: This is the first report to demonstrate the safety and efficacy of the Rituxan chimeric anti-CD20 antibody in combination with standard-dose CHOP in the treatment of aggressive B-cell lymphoma. The clinical responses are at least comparable to those achieved with CHOP alone with no significant added toxicity. The presence or absence of the bcl-2 translocation did not affect the ability of patients to achieve a CR with this regimen. The ability to achieve sustained remissions in patients with an IPI score > or = 2 warrants further investigation with a randomized study.

Attitudes toward euthanasia.

A 72-item questionnaire regarding attitudes toward euthanasia was administered to 240 residents of Humboldt County, California, who ranged from 18 to 86 years of age. The relationships between their attitudes and their demographic characteristics including age, religion, and education were examined.

Hypertrichosis cubiti.

Hypertrichosis is an unusual but well-recognized genetic condition. Hypertrichosis may be generalized or limited to specific body areas, in which case it is usually not associated with other anomalies. Five previous cases of hypertrichosis cubiti have been reported, with short stature in 2 sibs being the only other associated abnormalities. We report on a child with hairy elbows, developmental delay, facial asymmetry, and delayed speech with normal parents. Our patient may represent severe expression of the hairy elbow syndrome or constitute a previously unrecognized syndrome.

Laboratory experiments on planetary and stellar convection performed on spacelab 3.

Experiments on thermal convection in a rotating, differentially heated hemispherical shell with a radial buoyancy force were conducted in an orbiting microgravity laboratory. A variety of convective structures, or planforms, were observed, depending on the magnitude of the rotation and the nature of the imposed heating distribution. The results are compared with numerical simulations that can be conducted at the more modest heating rates, and suggest possible regimes of motion in rotating planets and stars.

Catabolic properties of aglycofibrinogen synthesized by tunicamycin-treated human hepatoma (HepG2) cells and rabbit hepatocytes.

Human hepatoma cell (HepG2) or rabbit hepatocyte monolayers were incubated with [35S]methionine in presence or absence of tunicamycin, a potent inhibitor of asparagine-linked glycosylation. The 35S-labeled nonglycosylated and control fibrinogens purified from the media were used to evaluate the influence of the oligosaccharide on the catabolic properties of this glycoprotein. Plasmin, pronase, cathepsin D or cathepsin B each degraded the nonglycosylated and control fibrinogens similarly, as evidenced by the release of trichloroacetic acid-soluble radioactivity and by SDS-polyacrylamide gel electrophoresis and autoradiography of plasmic digests. Nonglycosylated and control fibrin clots also showed no differences in susceptibility to plasmic digestion. The two forms of fibrinogen demonstrated the same plasma half-life in rabbits. These data indicate that the oligosaccharide does not influence the proteolytic stability or the in vivo plasma survival of fibrinogen, and suggest that other biochemical determinants may influence the catabolic properties of this molecule.

Leukemia risk among U.S. white male coal miners. A case-control study.

The relevance of occupational exposure to electrical and magnetic fields (EMF) in the etiology of leukemia has been raised in several studies. Underground coal miners represent an occupational group with situationally determined EMF exposure, as high-voltage power distribution lines are strung overhead in the mines and converters and step-down transformers provide power to mining equipment. Risk in occupational exposure to EMF was examined in a case-control study of 40 leukemia decedents and 160 control subjects who died of causes other than cancer or accident and who were matched on age at death. The control subjects were selected from a group of 6,066 persons whose deaths were reported in four National Institute for Occupational Safety and Health cohort mortality follow-up studies. Based on these data, 25 or more years of underground mining, a surrogate of EMF exposure, was found to pose a statistically significant risk for leukemia (International Classification of Diseases [ICD] codes 204 through 207, eighth revision), myelogenous leukemia (ICD 205), and chronic lymphocytic leukemia (CLL) (ICD 204.1). Accumulative exposure to chemical agents probably poses a risk for acute myelogenous leukemia, although this relationship fell short of being statistically significant. Although CLL has not previously been attributed to environmental agents, these data suggest a possible CLL risk from prolonged exposure to EMF.

Familial osteosarcoma associated with 13;14 chromosomal rearrangement.

Two prepubertal sisters of American Indian origin developed osteosarcoma at 8 and 12 years of age. This familial occurrence, tumor onset prior to puberty, unusual tumor location in one who also had short stature, and ethnic background all suggest an inborn predisposition to bone cancer rather than a chance occurrence. Rearrangements involving chromosomes #13 and #14 were found in both the surviving proband and mother. Comparison of the arm ratio and prometaphase G-banding patterns of the rearranged chromosomes suggests either deletion of band 14q11.2 or pericentric inversion (with breakpoints at 13q12 and 14q11.2) in the proband's rearranged chromosome, but not in her mother's. Her mother, who had no malignancy, had a typical Robertsonian translocation [t(13;14)(p11;q11)]. Three previously reported children with chromosomal abnormalities developed osteosarcoma at unusually young ages, younger even than in reported sibships with osteosarcoma. The most frequently detected cytogenetic abnormalities in sarcoma tumor cells involve chromosomes #13 and #14. In addition, some cases of bilateral retinoblastoma and familial unilateral retinoblastoma, which are known to be at increased risk for osteosarcoma, are associated with tiny deletions on chromosome #13. Thus, there may be a causal relationship between constitutional loss or rearrangement of genetic material at these breakpoints on chromosomes #13 or #14 and development of osteosarcoma in this family that is similar to that seen in patients with small constitutional chromosomal deletions who develop Wilms' tumor and retinoblastoma.

Diagnosis of thyroid dysfunction: applied kinesiology compared to clinical observations and laboratory tests.

Sixty-five patients presenting to three clinics were independently evaluated for thyroid dysfunction by applied kinesiology (AK), a clinical protocol, and laboratory testing. Each was rated on a scale of 1 (unquestionably hypothyroid) to 7 (unquestionably hyperthyroid). AK ratings correlated with clinical ratings (rs = .36, p less than .002) and with laboratory ratings (rs = .32, p less than .005). Correlation between clinical and laboratory ratings was .47, p less than .000. Three AK therapy localizations had a significant correlation with the laboratory diagnosis (p less than .05). Two of these (right neurovascular-left brain and left neurolymphatic-right brain) were points associated with thyroid function. The third, ventral hand on the glabella with the other on the external occipital protuberance, is associated with pituitary function. AK enhanced but did not replace clinical/laboratory diagnosis of thyroid dysfunction. Preliminary evidence indicates that there may be a significant correlation between certain AK tests and an elevated LDH in the serum.

Cerebral ischemia in the presence of lupus anticoagulant.

Two patients with manifestations of cerebral ischemia were found to have a circulating coagulation inhibitor. This immunoglobulin, termed lupus anticoagulant, results in a prolonged partial thromboplastin time. Paradoxically, it is usually associated with a thrombotic tendency rather than a bleeding diathesis. It is most commonly found in systemic lupus erythematosus, which our patients did not have. These two patients represent the interesting phenomenon of cerebral ischemia in the presence of an endogenous inhibitor of coagulation.