Common and Uncommon Anatomical Variants of Intrahepatic Bile Ducts in Magnetic Resonance Cholangiopancreatography and its Clinical Implication.

BACKGROUND: Preoperative knowledge of intrahepatic bile duct (IHD) anatomy is critical for planning liver resections, liver transplantations and complex biliary reconstructive surgery. The purpose of our study was to demonstrate the imaging features of various anatomical variants of IHD using magnetic resonance cholangio-pancreatography (MRCP) and their prevalence in our population. MATERIAL/METHODS: This observational clinical evaluation study included 224 patients who were referred for MRCP. MRCP was performed in a 1.5-Tesla magnet (Philips) with SSH MRCP 3DHR and SSHMRCP rad protocol. A senior radiologist assessed the biliary passage for anatomical variations. RESULTS: The branching pattern of the right hepatic duct (RHD) was typical in 55.3% of subjects. The most common variant was right posterior sectoral duct (RPSD) draining into the left hepatic duct (LHD) in 27.6% of subjects. Trifurcation pattern was noted in 9.3% of subjects. In 4% of subjects, RPSD was draining into the common hepatic duct (CHD) and in 0.8% of subjects into the cystic duct. Other variants were noted in 2.6% of subjects. In 4.9% of cases there was an accessory duct. The most common type of LHD branching pattern was a common trunk of segment 2 and 3 ducts joining the segment 4 duct in 67.8% of subjects. In 23.2% of subjects, segment 2 duct united with the common trunk of segment 3 and 4 and in 3.4% of subjects segment 2, 3, and 4 ducts united together to form LHD. Other uncommon branching patterns of LHD were seen in 4.9% of subjects. CONCLUSIONS: Intrahepatic bile duct anatomy is complex with many common and uncommon variations. MRCP is a reliable non-invasive imaging method for demonstration of bile duct morphology, which is useful to plan complex surgeries and to prevent iatrogenic injuries.

Is gender difference in postnatal thyroid growth associated with specific expression patterns of androgen and estrogen receptors?

Variations in sex steroids bioavailability were linked to the gender difference in the growth of thyroid glands of neonatal rats. In the present study we tested androgen receptor (AR) and estrogen receptor (ER) concentrations by ligand binding assay, and expression of their genes by RT-PCR and Western blot in the thyroid glands of neonatal rats. AR concentration remained elevated from postnatal day (PND) 10 onwards in males, whereas it decreased by PND 20 in females. AR mRNA and protein expressions were higher in males than females, which increased by PND 10, decreased after PND 15 and reached the nadir by PND 20. ER concentration increased by PND 10 and decreased thereafter in both sex. ERα mRNA expression diminished by PND 15 in both sex; while ERß mRNA decreased by PND 15 to reach the nadir by PND 20 in males, it was augmented by PND 10 in females to reach the peak by PND 15 and diminished by PND 20. ERα protein expression increased by PND 10 and remained elevated till PND 20 in both sex. ERß protein expression in males increased by PND 10 and decreased by PND 20, while it remained static up to PND 15 and decreased in females. Testosterone stimulated [(3)H]-thymidine uptake and the expression of IGF-1 and NIS genes in thyrocytes of both sex in vitro, while estradiol stimulated them in females but not in males. We conclude that androgens influence the growth and differentiation of thyrocytes through augmented expression of AR, IGF-1 and NIS in either sex, whereas estrogen imparts the gender difference, which may be at a level beyond the expression of ERs.

The Effect of Axial Load in the Tibia on the Response of the 90 degrees Flexed Knee to Blunt Impacts with a Deformable Interface.

Lower extremity injuries are a frequent outcome of automotive accidents. While the lower extremity injury criterion is based on fracture of bone, most injuries are of less severity. Recent studies suggest microscopic, occult fractures that have been shown to be precursors of gross bone fractures, may occur in the kneecap (patella) for impacts with rigid and deformable interfaces due to excessive levels of patello-femoral contact pressure. One method of reducing this contact pressure for a 90 degrees flexed knee is to provide a parallel pathway for knee impact loads into the tibial tuberosity. Yet, blunt loads onto the tibial tuberosity can cause posterior drawer motion of the tibia, leading to injury or rupture of the posterior cruciate ligament (PCL). Recently studies have shown that axial loads in the tibia, which are measured during blunt loading on the knee in typical automobile crashes, can induce anterior drawer motion of the tibia and possibly help unload the PCL. The purpose of the current study was to explore the effect of combined anterior knee loading (AKL) and axial tibia loading (ATL), on response and injury for the 90 degrees flexed human knee. In repeated impacts with increasing ATL the stiffness of the knee to an AKL impact increased. For a 3 kN AKL, the stiffness of the knee increased approximately 26% when the ATL was increased from 0 kN to 2 kN. For 6 kN and 9 kN AKL, the stiffness was increased approximately 17% and 20%, respectively, when the ATL was increased from 0 kN (uniaxial) to 4 kN (biaxial). The effect, however, was not statistically significant at the 9 kN AKL level. The posterior tibial drawer was shown to increase with increased AKL and decrease with increased levels of ATL at an average of 0.3 mm per kN ATL for both the 3 kN and 6 kN ATL scenarios. For 9 kN AKL this drawer displacement was significantly reduced for biaxial versus uniaxial impacts, from 7.4+/-1.4 mm to 5.8+/-0.6 mm, respectively. Additionally, the percentage of the load carried by the tibial tuberosity increased with an ATL. For AKL impacts of 3, 6, and 9 kN, the percentage of load carried by the tibial tuberosity increased from 2.1% (range 0-19%) to 4.9% (0-36%), 2.1% (0-15%) to 6.9% (0-36%), and 8.7% (0-25%) to 12.7% (0-33%), respectively, between uniaxial and biaxial tests. The biaxial loading scenario also resulted in a reduction of the patello-femoral (PF) contact force as the ATL was increased. Ten knee impacts resulted in PCL tears at an average peak load of 12.7+/-2.4 kN in biaxial impacts (n=5) and 12.0+/-3.1 kN for uniaxial impacts (n=5). These PCL injured specimens had an average age of 62+/-11.3 years. The remaining specimens (n=11, 78+/-12.9 years of age) had bone fractures at approximately 8.9+/-3.1 kN. This study showed that combinations of compressive ATL and AKL reduced the PF contact force and had a stiffening effect on the response of the knee impacting a stiff but deformable interface. Furthermore, ATL reduced the posterior drawer of the tibia, which is the current basis for PCL injury in the knee, although it did not reduce the incidence of PCL injury in this study. While the current injury tolerance criterion reflects the vulnerability of the PCL to injury by limiting tibial drawer to 15 mm, the current dummy design does not incorporate the stiffening effect of an ATL that may occur at the same time as knee contact with an instrument panel during a typical automotive crash.