The transepicondylar axis approximates the optimal flexion axis of the knee

The traditional understanding of knee kinematics holds that no single fixed axis of rotation exists in the knee. In contrast, a recent hypothesis suggests that knee kinematics are better described simply as two simultaneous rotations occurring about fixed axes. Knee flexion and extension occurs about an optimal flexion axis fixed in the femur, whereas tibial internal and external rotations occur about a longitudinal rotation axis fixed in the tibia. No other translations or rotations exist. This hypothesis has been tested. Tibiofemoral kinematics were measured for 15 cadaveric knees undergoing a realistic loadbearing activity (simulated squatting). An optimization technique was used to identify the locations of the optimal flexion and longitudinal rotation axes such that simultaneous rotations about them could best represent the measured kinematics. The optimal flexion axis was compared with the transepicondylar axis defined by bony landmarks. The longitudinal rotation axis was found to pass through the medial joint compartment. The optimal flexion axis passed through the centers of the posterior femoral condyles. No significant difference was found between the optimal flexion and transepicondylar axes. To an average accuracy of better than 3.4 mm in translation, and 2.9 degrees in orientation, knee kinematics were represented successfully by simple rotations about the optimal flexion and longitudinal rotation axes. The optimal flexion axis is fixed in the femur and can be considered the true flexion axis of the knee. The transepicondylar axis axis, which is identified easily by palpation, closely approximates the optimal flexion axis.     

Paths across generations: academic competence and aggressive behaviors in young mothers and their children

This research compared the social and cognitive development of young mothers when they were children with the social and cognitive development of their offspring. Intergenerational development was investigated over a 17-year period for 57 women who had been studied longitudinally from childhood to adulthood and who became young mothers (R. B. Cairns & B. D. Cairns, 1994). The children of these women, in turn, were followed prospectively from 1 to 2 years old through the early school years. The academic competence of mothers when they were children was significantly linked to the academic competence of their children at school age. In contrast, the across-generation correlations between measures of aggressive behavior of the mothers when they were children and measures of aggressive behavior of their children in early school grades were modest and unreliable. Certain within-generation continuities were observed in both cognitive and aggressive development.     

Decompensation of pressure-overload hypertrophy in G alpha q-overexpressing mice

BACKGROUND: Receptor-mediated activation of myocardial Gq signaling is postulated as a biochemical mechanism transducing pressure-overload hypertrophy. The specific effects of Gq activation on the functional and morphological adaptations to pressure overload are not known. METHODS AND RESULTS: To determine the effects of intrinsic myocyte G alpha q signaling on the left ventricular hypertrophic response to experimental pressure overload, transgenic mice overexpressing G alpha q specifically in the heart (G alpha q-25) and nontransgenic siblings underwent microsurgical creation of transverse aortic coarctation and the morphometric, functional, and molecular characteristics of these pressure-overloaded hearts were compared at increasing times after surgery. Before aortic banding, isolated G alpha q-25 ventricular myocytes exhibited contractile depression (depressed +dl/dt and -dl/dt) and G alpha q-25 hearts showed a pattern of fetal gene expression similar to the known characteristics of nontransgenic pressure-overloaded mice. Three weeks after transverse aortic banding, G alpha q-25 left ventricles hypertrophied to a similar extent (approximately 30% increase) as nontransgenic mice. However, whereas nontransgenic mice exhibited concentric left ventricular remodeling with maintained ejection performance (compensated hypertrophy), G alpha q-25 left ventricles developed eccentric hypertrophy and ejection performance deteriorated, ultimately resulting in left heart failure (decompensated hypertrophy). The signature hypertrophy-associated progress of fetal cardiac gene expression observed at baseline in G alpha q-25 developed after aortic banding of nontransgenic mice but did not significantly change in aortic-banded G alpha q-25 mice. CONCLUSIONS: Intrinsic cardiac myocyte G alpha q activation stimulates fetal gene expression and depresses cardiac myocyte contractility. Superimposition of the hemodynamic stress of pressure overload on G alpha q overexpression stimulates a maladaptive form of eccentric hypertrophy that leads to rapid functional decompensation. Therefore G alpha q-stimulated cardiac hypertrophy is functionally deleterious and compromises the ability of the heart to adapt to increased mechanical load. This finding supports a reevaluation of accepted concepts regarding the mechanisms for compensation and decompensation in pressure-overload hypertrophy.     

Inhibition of mitogen-activated protein kinase kinase blocks T cell proliferation but does not induce or prevent anergy

Three mitogen-activated protein kinase pathways are up-regulated during the activation of T lymphocytes, the extracellular signal-regulated kinase (ERK), Jun NH2-terminal kinase, and p38 mitogen-activated protein kinase pathways. To examine the effects of blocking the ERK pathway on T cell activation, we used the inhibitor U0126, which has been shown to specifically block mitogen-activated protein kinase/ERK kinase (MEK), the kinase upstream of ERK. This compound inhibited T cell proliferation in response to antigenic stimulation or cross-linked anti-CD3 plus anti-CD28 Abs, but had no effect on IL-2-induced proliferation. The block in T cell proliferation was mediated by down-regulating IL-2 mRNA levels. Blocking Ag-induced proliferation by inhibiting MEK did not induce anergy, unlike treatments that block entry into the cell cycle following antigenic stimulation. Surprisingly, induction of anergy in T cells exposed to TCR cross-linking in the absence of costimulation was also not affected by blocking MEK, unlike cyclosporin A treatment that blocks anergy induction. These results suggest that inhibition of MEK prevents T cell proliferation in the short term, but does not cause any long-term effects on either T cell activation or induction of anergy. These findings may help determine the viability of using mitogen-activated protein kinase inhibitors as immune suppressants.     

The barrier domain for solute permeation varies with lipid bilayer phase structure

Resting blood pressure in both white and black families participating in the HERITAGE Family Study was analyzed using a simple familial correlation model to assess familial influences. The two samples of black and white families were analyzed separately and together, providing an opportunity to test for heterogeneity in the familial resemblance. Maximal heritability was 46% for systolic blood pressure (SBP) and 31% for diastolic blood pressure (DBP) in the pooled sample. Noticeably higher heritabilities were found in the black sample (68% for SBP and 56% for DBP) than in the white sample (43% for SBP and 24% for DBP). The patterns of familial correlations were similar in blacks and whites, with the exception that spouse resemblance was significant in white families but not in black families. These results along with the finding that the magnitude of the familial correlations was higher in the black sample than in the white sample suggest that the effects of host and familial environmental factors differ between the races.     

Studies of bystander effects in human fibroblasts using a charged particle microbeam

PURPOSE: To determine the role of cell-to-cell mediated effects in the response of cells to different radiations by using a charged particle microbeam capable of targeting individual cells with counted particles. MATERIALS AND METHODS: Primary human fibroblasts were irradiated conventionally with X-rays or alpha-particles and scored for the induction of micronucleated or apoptotic cell formation at various times after irradiation. Cells were also individually irradiated with helium-3 particles from a microbeam and the distribution of damaged cells between hit and non-hit cells scored. RESULTS: Conventionally exposed fibroblasts showed a dose-dependent production of micronucleated and apoptotic cells 3 days after irradiation for both X-rays and alpha-particles, with a high RBE value for alpha-particles at low doses. Targeting individual alpha-particles, using a microbeam, to four cells within a population produced more micronucleated and apoptotic cells than expected on the basis of a direct effect only. CONCLUSIONS: This study provides direct evidence for the production of transmissible, cell-to-cell effects between hit and non-hit cells individually exposed to charged particles.     

Disulfide bond mapping and structural characterization of spruce budworm antifreeze protein

We have previously reported that bryostation 1 (Bryo 1) induces differentiation of chronic lymphocytic leukemia (CLL) in vitro to a hairy cell (HC) stage. This study tests the hypothesis that Bryo 1-differentiated CLL cells are more susceptible to 2-chlorodeoxyadenosine (2-CdA) than parent CLL cells. A recently established EBV-negative CLL line (WSU-CLL) from a patient resistant to chemotherapy including fludarabine was used to test this hypothesis. Both Bryo 1 (10-1000 nM) and 2-CdA (5.6-22.4 microM) exhibited a dose-dependent growth inhibitory effect on the WSU-CLL cell line. In vitro, the sequential exposure to Bryo 1 (100 nM for 72 h) followed by 2-CdA (11.2 microM) resulted in significantly higher rates of growth inhibition than either agent alone. Changes in immunophenotype, enzymes, lipids, proteins, and the DNA of WSU-CLL cells were studied before and after Bryo 1 treatment. Bryo 1 induced a positive tartrate-resistant acid phosphatase reaction and two important markers, CD11c and CD25, after 72 h of culture, confirming the differentiation of CLL to HC. The Fourier transformation infrared spectroscopic analysis showed that the amount of membrane lipids significantly increased in Bryo 1-treated cells compared to controls after 24 h, whereas the protein content, as well as the DNA content, decreased. This finding supports the change of CLL to HC. To evaluate the in vivo efficacy of Bryo 1 and 2-CdA, we used a xenograft model of CLL in WSU-CLL-bearing mice with severe combined immune deficiency. s.c. tumors were developed by injection of 10(7) WSU-CLL cells, and fragments were then transplanted into a new batch of severe combined immunodeficient mice. Bryo 1 and 2-CdA at the maximum tolerated doses (75 micrograms/kg i.p. and 30 mg/kg s.c., respectively) were administered to the mice at different combinations and schedules. The survival in days, the tumor growth inhibition ratio, the tumor growth delay, and the log10 kill of the mice treated with Bryo 1 followed by 2-CdA were significantly better than the control and other groups. We conclude that the sequential treatment with Bryo 1 followed by 2-CdA resulted in higher antitumor activity and improved animal survival.     

Predictive value of monitoring parameters in fetal surgery

BACKGROUND/PURPOSE: The choice of monitoring parameters in fetal surgery has thus far been based on feasibility rather than on predictability. Ideally, monitoring should be noninvasive, have a rapid response time and high sensitivity, and be applicable to open and endoscopic techniques. Herein, the authors studied the response of several parameters to standardized episodes of fetal ischemia and stress. METHODS: Eight time-dated fetal lambs (110 days, term, 145 days) were used. Under general anesthesia, a balloon occluder was placed around the umbilical cord. Pulse oximetry (POx + heart rate, HR), electrocardiography (ECG), direct oximetry (DOx), and blood pressure (BP) were recorded continuously. After stabilization, the umbilical cord was completely occluded for 5 seconds, then released. False-negative recordings were defined as failure of a parameter to respond to umbilical occlusion; false-positive episodes were defined as 10% change in value over < or = 10 seconds during stabilization (baseline) period. RESULTS: The fetuses were monitored for an aggregate of 358 minutes. Baseline DOx was 64%+/-5%, POx, 66%+/-16%; HR, 141+/-18 beats per minute (bpm); systolic BP (SBP), 51+/-3 torr; and diastolic BP (DBP), 38+/-2 torr. During umbilical occlusion (n=15), SBP increased to 56+/-3 torr and DBP to 43+/-2 torr at 0.5 seconds, then returned to baseline at 8.0 seconds. A decrease was seen in DOx (start at 3.5s, maximum delta 9.9+/-1.5% at 10.5 seconds) and POx (start at 4.2 seconds, maximum delta 7.3+/-2.4% at 20.5 seconds). Heart rate showed <10% decrease (start at 8.5 seconds, nadir 131+/-14 bpm at 19.5 seconds). No ECG changes were noted. Sensitivity was 100% for DOx, POx, and BP, but only 14% for HR; specificity was 97% for DOx and 88% for POx; positive predictive value was 58% for DOx and 37% for POx; negative predictive value was 100% for DOx and POx. CONCLUSIONS: Direct intravascular oximetry and blood pressure provide a prompt and reliable response to acute fetal stress, but are too invasive for routine use. Bradycardia is an insensitive and late sign of fetal distress. Pulse oximetry has a rapid response time (<5 seconds), high sensitivity, and negative predictive value. In addition, its application is noninvasive and has proven to be feasible in open and endoscopic fetal surgical procedures. It therefore appears to be the monitoring parameter of choice for fetal surgery.     

Management and after-care of extensor tendon injuries of the hand

The investigation and management of extensor tendons play a minor role compared to those of flexor tendons. The finger extension does not seem to be as important as the flexion. But the practical value of the hand is determined by both. Different managements are used depending on the level of extensor tendon injury. More distal located injuries require a longer restraint than those, which are located more proximal. On the one hand this depends on the blood supply of the extensor tendon, which is by far better in the lower arm and dorsal hand than peripheral. On the other hand the reason is the different amplitude of gliding of extensor tendons, which decreases from proximal to distal to lower than 1 mm. Therefore the tension on extensor tendon sutures increases from proximal to distal. The varies techniques of extensor tendon reconstruction will be described.     

Effects of hypesthesia on oral behaviors of the orthognathic surgery patient

PURPOSE: The purpose of this study was to compare orthognathic surgery patients with and without significant hypesthesia with respect to perceived problems with specific oral behaviors. PATIENTS AND METHODS: Data from 116 patients 6 months after bilateral sagittal split osteotomy (BSSO) and mandibular advancement were analyzed. Tactile sensation in the right and left mental nerve areas was determined using monofilaments and brush strokes (von Frey hairs). The right infraorbital region was used as a control. A difference of 450 mg of force between the control and test sites was considered significant hypesthesia. Patients rated their level of subjective problems with swallowing liquids or solids, smiling, spitting, kissing, speaking, eating, and drooling on a scale from 1 (none to mild) to 7 (extreme). A value of 5 or greater was considered significant impairment. RESULTS: Hypesthesia was shown in 23 patients (19.8%) with the monofilaments and in 29 patients (25.0%) using brush stroke direction. In each of these two groups, a significant correlation was observed between hypesthesia and difficulty in chewing and kissing. No correlation was observed between any of the remaining seven oral behaviors and hypesthesia. CONCLUSION: These findings suggest that only certain oral behaviors are affected by hypesthesia of the mental nerve.