HopX1 in Erwinia amylovora functions as an avirulence protein in apple and is regulated by HrpL.

Fire blight is a devastating disease of rosaceous plants caused by the Gram-negative bacterium Erwinia amylovora. This pathogen delivers virulence proteins into host cells utilizing the type III secretion system (T3SS). Expression of the T3SS and of translocated and secreted substrates is activated by the alternative sigma factor HrpL, which recognizes hrp box promoters upstream of regulated genes. A collection of hidden Markov model (HMM) profiles was used to identify putative hrp boxes in the genome sequence of Ea273, a highly virulent strain of E. amylovora. Among potential virulence factors preceded by putative hrp boxes, two genes previously known as Eop3 and Eop2 were characterized. The presence of functionally active hrp boxes upstream of these two genes was confirmed by ß-glucuronidase (GUS) assays. Deletion mutants of the latter candidate genes, renamed hopX1(Ea) and hopAK1(Ea), respectively, did not differ in virulence from the wild-type strain when assayed in pear fruit and apple shoots. The hopX1(Ea) deletion mutant of Ea273, complemented with a plasmid overexpressing hopX1(E)(a), suppressed the development of the hypersensitivity response (HR) when inoculated into Nicotiana benthamiana; however, it contributed to HR in Nicotiana tabacum and significantly reduced the progress of disease in apple shoots, suggesting that HopX1(Ea) may act as an avirulence protein in apple shoots.

Complete genome sequence of the plant pathogen Erwinia amylovora strain ATCC 49946.

Erwinia amylovora causes the economically important disease fire blight that affects rosaceous plants, especially pear and apple. Here we report the complete genome sequence and annotation of strain ATCC 49946. The analysis of the sequence and its comparison with sequenced genomes of closely related enterobacteria revealed signs of pathoadaptation to rosaceous hosts.

The influence of obesity and consequent insulin resistance on coronary risk factors in medically treated patients with coronary disease.

OBJECTIVE: Obesity promotes the development and progression of coronary heart disease (CHD), in part, through its association with hyperlipidemia, hypertension, clotting abnormalities and insulin resistance. We assessed whether these relationships persist in patients with established CHD treated with evidence-based preventive pharmacologic therapies. DESIGN AND SUBJECTS: We performed a cross-sectional study of 74 adults with CHD and a body mass index (BMI) of >27 kg m(-2) (mean 32+/-4). The mean age of subjects was 64+/-9 years (range 44-84 years). MEASUREMENTS: Obesity measures included weight, BMI, waist, fat mass, intra-abdominal fat and subcutaneous fat. Risk factor measures included insulin sensitivity, fasting insulin level, lipid profiles, blood pressure, C-reactive protein (hs-CRP), plasminogen activator inhibitor (PAI-1) and platelet reactivity. Medication use included aspirin (99%), statin (84%), beta-blocker (71%), ACE inhibitor or blocker (37%) and clopidogrel (28%). RESULTS: There was no direct relationship between obesity parameters and risk factor measures of lipid concentrations, blood pressure, clotting abnormalities or platelet reactivity except for a modest relationship between visceral fat and hs-CRP (r=0.30, P=0.02). However, increased BMI, waist circumference, fat mass, total abdominal fat and abdominal subcutaneous fat all correlated with insulin sensitivity (r-values -0.30 to -0.45, P-values 0.01 to <0.001) and insulin concentrations. Insulin sensitivity, in turn, was the best predictor of PAI-1, triglycerides, high-density lipoprotein (HDL) levels, cholesterol/HDL levels (all P<0.01) and platelet reactivity (R=0.34, P=0.02). CONCLUSIONS: Use of preventive pharmacologic therapies obviated the expected relationship between adiposity and CHD risk factors. However, a residual effect of insulin resistance is left untreated. Total adiposity and central adiposity were strong predictors of insulin sensitivity, which in turn predicted cardiac risk factors such as lipid concentrations, PAI-1 and platelet reactivity. Thus, while evidence-based pharmacologic treatments may diminish the statistical relationship between obesity and many cardiac risk factors, adiposity negatively impacts CHD risk by reducing tissue insulin sensitivity.

Overview of interventional pediatric cardiology in 2004.

Pediatric interventional catheterization is an expanding specialty with a range of mature, emerging, and investigative procedures and technologies. Many dysfunctional obstructions and/or shunts caused by congenital heart defects may be treated or significantly palliated in the catheterization laboratory. These include valvar pulmonary or aortic stenosis, the patent ductus arteriosus, coarctation of the aorta, branch pulmonary stenosis, atrial septal defects and even ventricular septal defects. Valve replacement technology, approaches to complex heart diseases such as single ventricle, and fetal interventions are subjects of active investigations. A comprehensive review of the present and future of interventional pediatric cardiology is presented.

The effect of washing water on bonding to etched enamel.

There is current concern about bacterial contamination of dental unit waterlines. This research hypothesized that the presence of increasing concentrations of bacteria in water used to wash etched enamel would result in a corresponding decrease in both shear bond strength (SBS) and critical surface tension (gammaC) of enamel. A further hypothesis was made that there is a correlation between SBS and gammaC. The effect of 3.5 ppm iodine in the water as a bacteriostatic agent was also assessed. Five groups of 10 samples of bovine enamel were etched, washed, and a resin composite bonded to them. The control group was washed with distilled water. Another group was washed with the dilute iodine solution. The remaining three groups used a different concentration of Escherichia coli DH5alpha as follows (in cfu mL(-1)): group 1: 10(2); group 2: 10(4); group 3: 10(6). Shear bond strength data were measured on an Instron testing machine at a crosshead speed of 1 mm min(-1). Adhesion data were (MPa): control: 24.6 +/- 6.0; with iodine: 20.8 +/- 2.7; group 1: 19.8 +/- 2.7; group 2: 13.5 +/- 3.0; group 3: 13.9 +/- 3.6. The F-test yielded a highly significant difference between control group, iodine group and group 1, compared with groups 2 and 3 (P < 0.0001). Tukey's Studentized Range Test was used for pairwise comparison testing between groups. Using a Cahn dynamic contact angle analyzer and linear regression analysis, the plots of surface tension versus costheta were extrapolated to costheta = 1 to give gammaC data for the control group and groups 1-3. In all cases reasonable linearity was observed (r2 > or = 0.87). Data (mN m(-1)) were: control group: 50.8; group 1: 45.1; group 2: 43.2; group 3: 39.5. The SBS and gammaC were then plotted against each other and linear regression analysis performed. It was concluded that increasing concentrations of bacteria in wash water decreased both SBS and gammaC and that a linear correlation (R2 = 0.84) was found between the values of these two parameters.

Augmentation of inhibitory effects of glycoprotein IIb-IIIa antagonists in patients with diabetes.

BACKGROUND: Patients with diabetes mellitus and acute coronary syndromes (ACS) derive enhanced benefit from treatment with glycoprotein (GP) IIb-IIIa inhibitors. To determine mechanisms potentially responsible we characterized the binding of fibrinogen to platelets from patients with and without diabetes in the presence and absence of GP IIb-IIIa antagonists. METHODS: GP IIb-IIIa antagonists (tirofiban, eptifibatide, and abciximab) were added in vitro to blood from patients with and without diabetes. Binding of fibrinogen to activated GP IIb-IIIa was assessed with the use of flow cytometry. The kinetics of binding of I(125)-abciximab and I(125)-fibrinogen to washed platelets from subjects with and without diabetes mellitus were determined. Glycation of platelet membrane proteins was measured with the fructosamine assay. RESULTS: In the presence of GP IIb-IIIa antagonists, activation-induced binding of fibrinogen to platelets was reduced to a greater extent (p<0.02) in blood from patients with diabetes. The greater inhibition in blood from patients with diabetes was seen with pharmacologic concentrations of tirofiban (50 ng/ml, by 27%), eptifibatide (1.5 microg/ml, by 24%), and abciximab (2 mg/ml, by 12%). Whereas the binding of I(125)-abciximab was similar to platelets from patients with diabetes and those without, the rate of binding of I(125)-fibrinogen was decreased with platelets from patients with diabetes. Binding after 5 min was reduced by 46% in those with diabetes (p<0.05). Platelet membrane proteins from patients with diabetes were glycated to a greater extent compared with those without diabetes. CONCLUSION: GP IIb-IIIa antagonists inhibit platelet activation to a greater extent in blood from patients with diabetes. The decreased rate of binding of fibrinogen early after activation of platelets appears to be a consequence of glycation and may promote inhibition by GP IIb-IIIa antagonists.

Effects of insulin sensitizers on plaque vulnerability associated with elevated lipid content in atheroma in ApoE-knockout mice.

Acute coronary syndromes are generally precipitated by rupture of lipid-laden, relatively acellular, vulnerable atherosclerotic plaques with thin fibrous caps. We investigated whether a high-fat diet alters insulin sensitivity and whether insulin sensitizers (troglitazone and rosiglitazone) alter the composition of otherwise lipidladen atherosclerotic plaques in mice deficient in apolipoprotein E (ApoE). ApoE-knockout mice were fed a high-fat (n=30) or standard chow (n=10) diet for two weeks. Thereafter, those fed the high-fat diet were treated with troglitazone (n=10), rosiglitazone (n=10) or no drug (n=10) for 16 weeks beginning at 8 weeks of age. Carbohydrate metabolism was assessed with intraperitoneal glucose tolerance tests and insulin tolerance tests. Plaque composition was characterised with confocal laser scanning microscopy. The high-fat diet induced insulin resistance in the absence of weight gain. Compared with control animals on the high-fat diet, animals given troglitazone (400 mg/kg/day) or rosiglitazone (4 mg/kg/day) had significantly less area under the curve (AUC) for insulin ( p<0.05) and glucose disposal ( p<0.05). Despite significant increases in insulin sensitivity with drug treatment, no change in HDL-cholesterol and triglyceride levels, nor reduction in atheroma size or lipid content was noted. Thus, improvement in insulin resistance induced by a high-fat diet in this animal model of vasculopathy did not alter plaque composition.

Effect of fatty acid chain length and thioesterification on the augmentation of expression of plasminogen activator inhibitor-1.

BACKGROUND AND AIM: Concentrations in blood of plasminogen activator inhibitor type 1 (PAI-1) and circulating free (non-esterified) fatty acids (FFA) are increased in diabetes and may accelerate atherosclerosis. We have shown that FFA increase expression of PAI-1 by activation of a transcription factor that binds to the repeated sequence 5'-TG(G/C) 1-2CTG-3'. This study was designed to determine whether FFA chain length, saturation, or both affect agonist properties and whether agonist properties are mediated by activated, thioesterified FFA (fatty acyl-CoA). METHODS AND RESULTS: Human hepatoma cells were exposed to selected FFA associated with bovine serum albumin (BSA). Triacsin C (5 microM) was used to inhibit production of fatty acyl-CoA. PAI-1 was assayed by enzyme linked immunosorbent assay. Maximal induction of PAI-1 was similar with medium and long chain FFA (fold induction of PAI-1 accumulated in conditioned media compared with control: C10 = 1.8 +/- 0.1, C12 = 2.0 +/- 0.1, C14 = 2.0 +/- 0.2, C16 = 1.4 +/- 0.1, C18 = 1.6 +/- 0.1, C20 = 1.32 +/- 0.1, p < 0.005 for each compared with control). Increased unsaturation did not alter the agonist properties of FFA (fold induction with C16: 0 = 1.4 +/- 0.1, C16: 1 = 1.4 +/- 0.1; C18: 0 = 1.6 +/- 0.1, C18: 1 = 1.5 +/- 0.1, C18: 2 = 1.6 +/- 0.1, C18: 3 = 1.4 +/- 0.1 and C20: 4 = 1.3 +/- 0.1, C20: 5 = 1.4 +/- 0.1, n = 6). However, maximal effects were seen with lower concentrations of longer chain FFA. Triacsin C consistently attenuated effects of FFA. CONCLUSIONS: Longer chain FFA exhibit maximal effects at lower concentrations. Augmented expression of PAI-1 is mediated by the fatty acyl-CoA derivative. These criteria identify targets for therapy designed to normalize expression of PAI-1 and retard progression of atherosclerosis in subjects with elevated concentrations of FFA in blood including those with insulin resistance.

Platelet reactivity in coronary ostial blood: a reflection of the thrombotic state accompanying plaque rupture and of the adequacy of anti-thrombotic therapy.

BACKGROUND: Optimal anti-thrombotic therapy for acute coronary syndromes (ACS) should suppress pro-thrombotic activity at the site of plaque rupture. We sought to determine whether platelet reactivity is increased in blood in the immediate vicinity of a ruptured plaque and is apparent even when blood is obtained by sampling from a catheter placed proximal to the lesion. METHODS: Blood was obtained from a catheter placed in the aorta and from the same catheter after engaging the culprit coronary artery. Platelet reactivity was determined with the use of flow cytometry by surface expression of P-selectin. RESULTS: In preliminary studies we demonstrated that a marker of thrombin activity, fibrinopeptide A, was similarly increased in blood taken from the coronary sinus and coronary arterial ostium of patients with ACS. Subsequently blood was obtained from the aorta and coronary arterial ostium through a coronary guide catheter for assessment of platelet reactivity in 23 subjects with ACS and 22 subjects with stable angina. The percentage of platelets expressing P-selectin in response to 0.2 microM adenosine diphosphate (ADP) was greater in coronary arterial samples from patients with ACS (aorta=6.1+/-1%, coronary artery=8.8+/-1.6%, p=0.02) compared with that in patients with stable symptoms (aorta=6.9+/-1.2, coronary artery=6.5+/-1.4, p=NS). CONCLUSIONS: Coronary arterial blood obtained from the ostium through a coronary guide catheter can be used to determine whether thrombin activity and platelet reactivity are increased in the immediate vicinity of a ruptured atherosclerotic plaque. The simplicity of the approach developed should facilitate its use in future studies designed to determine the impact of optimal suppression of platelet reactivity and the pro-thrombotic state before coronary interventions on short- and long-term clinical outcomes.

Platelet reactivity characterized prospectively: a determinant of outcome 90 days after percutaneous coronary intervention.

BACKGROUND: Platelet activation is pivotal in the pathogenesis of complications after percutaneous coronary interventions (PCI). We previously reported substantial interindividual variability in activation of glycoprotein (GP) IIb/IIIa in response to a low concentration of ADP. We assessed GP IIb/IIIa activation prospectively to determine whether this could differentiate patients at low risk from those at high risk for complications early and late after PCI. Methods and Results-- A total of 112 patients undergoing PCI were studied. Platelet reactivity was determined with the use of flow cytometry. Patients were classified into high and low platelet reactivity groups on the basis of extent of activation of GP IIb/IIIa in response to 0.2 micromol/L ADP. The median value was used for differentiation. The incidence during 90-day follow-up interval of a composite end point (myocardial infarction, urgent revascularization, or repeat revascularization) was determined in each group. Follow up was completed in all 112 patients. The 2 groups were similar with respect to diverse clinical characteristics. Nevertheless, the incidence of the composite end point occurred in 26.8% of the high and 7.1% in the low platelet reactivity group (P=0.01). The difference in the composite end point was most striking during the 30- to 90-day interval after PCI (16.7% versus 1.9%; P=0.02). Repeat revascularization was more frequent in those with increased platelet reactivity (17.9% versus with 3.6%, P=0.029). CONCLUSIONS: Prospective assessment of platelet GP IIb/IIIa activation permits stratification of patients into low- and high-risk groups with respect to adverse events after PCI.

Quantification by flow cytometry of the efficacy of and interindividual variation of platelet inhibition induced by treatment with tirofiban and abciximab.

BACKGROUND: After exposure of platelets to abciximab and tirofiban in vitro, we have observed variable inhibition of fibrinogen binding and a lack of inhibition of alpha-granule degranulation. DESIGN: To determine whether such changes occur with treatment, platelet reactivity was assayed in blood from 50 patients receiving abciximab or tirofiban. METHODS: Platelet reactivity was determined before and during steady-state infusions of abciximab (0.125 microg/kg/min) or tirofiban, with either the PRISM-PLUS dosage (0.1 microg/kg/min) or the RESTORE dosage (0.15 microg/kg/min). Fibrinogen binding and P-selectin expression were determined by flow cytometry after stimulation of platelets with ADP (0.2 or 1 microM) or thrombin-receptor agonist peptide (TRAP, 25 microM). RESULTS: Both dosages of tirofiban and abciximab reduced fibrinogen binding in response to 0.2 microM ADP comparably. However, fibrinogen binding in response to 1.0 microM ADP or 25 microM TRAP was inhibited to a greater extent by the RESTORE dosage of tirofiban and abciximab than by the PRISM-PLUS dosage of tirofiban (P< 0.05). Furthermore, only the RESTORE dosage of tirofiban and abciximab reduced P-selectin expression in response to ADP. Inhibition with each regimen varied markedly between patients. CONCLUSIONS: The RESTORE dosages of tirofiban and abciximab each inhibit fibrinogen binding and alpha-granule degranulation similarly. However, substantial interindividual variation in inhibition of fibrinogen binding is evident.

Transcatheter treatment of IVC channel obstruction and baffle leak after Mustard procedure for d-transposition of the great arteries using Amplatzer ASD device and multiple stents.

A patient with d-transposition of the great arteries who underwent the Mustard operation at one year of age developed intermittent symptomatic cyanosis as a young adult. Evaluation demonstrated a large baffle leak with bidirectional flow and stenosis of the intra-atrial IVC baffle channel. Initially, a single stent was placed to relieve the obstruction, followed by placement of an Amplatzer septal occluder device which assumed suboptimal position after release. Placement of additional stents securely repositioned the ASD device into excellent position, resulting in complete occlusion of the baffle leak and no residual obstruction in the IVC channel.

Time and dose dependent augmentation of inhibitory effects of abciximab by aspirin.

Aspirin and abciximab independently decrease the incidence of cardiac events. To identify potential interactions, antiplatelet effects of abciximab were characterized in blood from healthy subjects given aspirin. Platelet activation was determined in whole blood with and without abciximab (2 microg/ml) added in vitro. Flow cytometry was used to quantify fibrinogen binding (glycoprotein IIb-IIIa activation). Binding of fluorochrome-labeled and 125I-labeled abciximab was determined before and after exposure to aspirin. In blood from subjects given aspirin for 5 days, abciximab-induced inhibition of the capacity to bind fibrinogen in response to 1 microM ADP was greater when the daily dose had been 325 mg compared with 81 mg (% inhibition: no aspirin 53 +/- 6; 81 mg daily 62 +/- 5; 325 mg daily 69 +/- 6). The effect of 5 daily doses of aspirin was greater than that of one. Larger single doses elicited larger effects (% inhibition 2 h after 325 mg 59 +/- 6; 2 h after 650 mg 78 +/- 5). Neither salicylsalicylic acid nor naproxen sodium potentiated the effect of abciximab. Exposure of platelets to 14C-acetylsalicylic acid led to acetylation of glycoprotein IIb and IIIa. Binding of 125I-abciximab to platelets was increased after 30 and 60 min. Acetylation of glycoprotein IIb-IIIa by aspirin augments inhibitory effects of abciximab in a dose- and time-dependent manner by increasing binding of abciximab to platelets.

The duct-occlud device: design, clinical results, and future directions.

The successful employment of embolization coils for transcatheter occlusion of the patent ductus arteriosus (PDA) has resulted in acceptance of transcatheter occlusion as the treatment of choice for small to medium-sized PDAs. The Duct-Occlud device was developed to further improve the technique by utilizing a controlled release mechanism and coil shape specifically designed for the geometry of the ductus arteriosus. Clinical studies have demonstrated excellent efficacy with low embolization rates and low incidences of complications. Newer modifications have been designed for occlusion of larger PDAs and subaortic ventricular septal defects, and preliminary clinical results have been promising.

Identification and localization of a fatty acid response region in the human plasminogen activator inhibitor-1 gene.

The increased expression of plasminogen activator inhibitor type-1 (PAI-1) is associated with increased concentrations of fatty acids in blood and may accelerate atherogenesis in diabetes. The present study was designed to define mechanisms by which nonesterified (free) fatty acids (FFAs) augment the expression of PAI-1. FFAs increased PAI-1 protein and mRNA expression by HepG2 cells. To identify potential regulatory elements, we constructed chimeric genes by fusing 1313, 853, 610, or 328 bp of human PAI-1 5'-flanking DNA to a luciferase reporter (PAI-LUC). A 2-fold increase in luciferase activity was seen when cells were transfected with PAI-LUC 1313, 863, or 610 and exposed to FFAs. No response to FFAs was seen with PAI-LUC 328 and after deletion of a 72-bp (-599 to -528) fragment from PAI-LUC 1313. This 72-bp fragment conferred FFA responsiveness to a different (simian virus 40) promoter. Two footprinted regions were demonstrated by DNase I analysis. Gel mobility shift assays indicated specific binding of extracted proteins to an FFA response element: 5'-TG(G/C)(1-2)CTG-3'. This sequence is repeated 4 times and is similar to an Sp1-binding site. Sp1 consensus oligonucleotides inhibited binding of extracted proteins to the regulatory elements. Accordingly, FFA-induced increased expression of PAI-1 in HepG2 cells is mediated by the binding of a transcription factor or factors to the repeated fatty acid response element, 5'-TG(G/C)(1-2)CTG-3', that is highly homologous to an Sp1-binding site.

Novel, bedside, tissue factor-dependent clotting assay permits improved assessment of combination antithrombotic and antiplatelet therapy.

BACKGROUND: Because optimal use of combinations of antiplatelet and antithrombotic drugs requires improved methods for assessment of therapeutic efficacy, we developed an assay designed to increase sensitivity that is based on initiation of clotting by tissue factor in minimally altered whole blood. METHODS AND RESULTS: Blood samples were obtained from healthy subjects, and the contact pathway of coagulation was inhibited with corn trypsin inhibitor (a specific factor XIIa inhibitor without effect on other coagulation factors). Clotting was initiated with relipidated tissue factor and detected with a Hemochron ACT instrument. Results were reproducible with samples from 25 healthy volunteers (mean time to clot, 125+/-17 seconds). Blood was also exposed to pharmacological concentrations of antithrombotic and antiplatelet agents in vitro. Heparin (0.25 anti-IIa/Xa U/mL) prolonged the time to clot by 2.4-fold (172 seconds, P:<0.05); hirudin (1.0 anti-IIa U/mL), by 3-fold (250 seconds P:<0.05); and enoxaparin (0.6 anti-Xa U/mL), by 2 -fold (123 seconds, P:<0.05). Additive effects of antiplatelet agents were readily detectable with both heparin and hirudin. Thus, addition of 3 microg/mL abciximab to 1.0 anti-IIa/Xa U/mL heparin and to 1.0 anti-IIa U/mL hirudin further prolonged the times to clot by 140 and 67 seconds, respectively (P:<0.05 for each). Addition of abciximab to enoxaparin did not further prolong the time to clot (increment, 13 seconds; P:=NS). CONCLUSIONS: The assay developed should facilitate improved dose selection, titration, and monitoring of combination antithrombotic and antiplatelet treatment regimens.

The consequences of anterior femoral notching in total knee arthroplasty. A biomechanical study.

BACKGROUND: Notching of the anterior femoral cortex during total knee arthroplasty has been implicated as a cause of subsequent periprosthetic supracondylar femoral fracture. However, other than observational clinical data, no reliable association between these events has been established, to our knowledge. The purpose of the present study was to investigate the biomechanical effects of notching of the anterior femoral cortex. METHODS: The femoral component of a total knee replacement was implanted in twelve matched pairs of human cadaveric femora; one specimen in each pair had preservation of the anterior femoral cortex, and the other had a full-thickness cortical defect created just proximal to the anterior flange of the femoral component. The pairs were then subjected to either bending or torsional loading to failure. Both the fracture pattern and the quantitative load to failure were analyzed. Two matched pairs were excluded from the analysis because of inadvertent fracture during placement of the component. RESULTS: Following the application of a bending load, femora with notching of the anterior femoral cortex sustained a short oblique fracture that originated at the cortical defect proximal to the femoral component and femora without notching had a midshaft fracture. In contrast, notching of the anterior femoral cortex had no effect on the fracture pattern that was observed after the application of a torsional load. The mean load to failure was significantly reduced by notching in both testing modes. Notching decreased bending strength from 11,813 to 9690 newtons (18 percent; p = 0.0034), and it decreased torsional strength from 134.7 to 81.8 newton-meters (39.2 percent; p = 0.01). CONCLUSIONS: Biomechanical testing demonstrated that notching of the anterior femoral cortex significantly lessens the load to failure following total knee arthroplasty and influences the subsequent fracture pattern. These effects are manifested in different ways under the two loading conditions: the fracture pattern is altered under bending load, and there is a greater quantitative decrease in load to failure with torsional loading. CLINICAL RELEVANCE: Weakening of the femur by notching of the anterior cortex after total knee arthroplasty may warrant alteration in the customary postoperative regimen for these patients. Manipulation of a total knee replacement with a notched anterior femoral cortex should probably be avoided.

Chondronecrosis of the hip. The protective role of the ossific nucleus in an animal model.

The presence of the ossific nucleus and its role in reducing the risk of ischemic necrosis in developmental dysplasia of the hip remains a matter of controversy. Ischemic necrosis of the pre-osseous capital femoral epiphysis, defined as chondronecrosis, was evaluated in a rabbit model. Histologic evidence of chondronecrosis after casting in maximum abduction was greater in 1-day-old New Zealand White rabbits before the radiographic appearance of the ossific nucleus, compared with 16-day-old New Zealand White rabbits with an ossific nucleus already present. This preliminary study supports the hypothesis that the ossific nucleus may decrease the risk of intracapsular compressive ischemic injury to the developing capital femoral epiphysis in a rabbit model.

Factor V Leiden mutation and the risk of thrombo-embolic disease in pregnancy: a case report.

Factor V Leiden mutation is a risk factor for the development of thrombo-embolic episodes in pregnancy. A case is presented of a pregnant woman with repeated episodes of venous thrombosis with a complicated clinical course.