Comparing human and mouse salivary glands: A practice guide for salivary researchers

Mice are a widely utilized in vivo model for translational salivary gland research but must be used with caution. Specifically, mouse salivary glands are similar in many ways to human salivary glands (i.e., in terms of their anatomy, histology, and physiology) and are both readily available and relatively easy and affordable to maintain. However, there are some significant differences between the two organisms, and by extension, the salivary glands derived from them must be taken into account for translational studies. The current review details pertinent similarities and differences between human and mouse salivary glands and offers practical guidelines for using both for research purposes.     

Live high,train low – influence on resting and post‐exercise hepcidin levels

The post‐exercise hepcidin response during prolonged (>2 weeks) hypoxic exposure is not well understood. We compared plasma hepcidin levels 3 h after exercise [6 × 1000 m at 90% of maximal aerobic running velocity (vVO_2max)] performed in normoxia and normobaric hypoxia (3000 m simulate altitude) 1 week before, and during 14 days of normobaric hypoxia [196.2 ± 25.6 h (median: 200.8 h; range: 154.3–234.8 h) at 3000 m simulated altitude] in 10 well‐trained distance runners (six males, four females). Venous blood was also analyzed for hepcidin after 2 days of normobaric hypoxia. Hemoglobin mass (Hb_mass) was measured via CO rebreathing 1 week before and after 14 days of hypoxia. Hepcidin was suppressed after 2 (Cohen's d = ?2.3, 95% confidence interval: [?2.9, ?1.6]) and 14 days of normobaric hypoxia (d = ?1.6 [?2.6, ?0.6]). Hepcidin increased from baseline, 3 h post‐exercise in normoxia (d = 0.8 [0.2, 1.3]) and hypoxia (d = 0.6 [0.3, 1.0]), both before and after exposure (normoxia: d = 0.7 [0.3, 1.2]; hypoxia: d = 1.3 [0.4, 2.3]). In conclusion, 2 weeks of normobaric hypoxia suppressed resting hepcidin levels, but did not alter the post‐exercise response in either normoxia or hypoxia, compared with the pre‐exposure response.     

Sensitivity of MR diffusion measurements to variations in intracellular structure: Effects of nuclear size

Magnetic resonance imaging measurements of the apparent rate of water diffusion in tumors are sensitive to variations in tissue cellularity, which have been shown useful for characterizing tumors and their responses to treatments. However, because of technical limitations on most MRI systems, conventional pulse gradient spin echo (PGSE) methods measure relatively long time scales, during which water molecules may encounter diffusion barriers at multiple spatial scales, including those much greater than typical cell dimensions. As such they cannot distinguish changes on subcellular scales from gross changes in cell density. Oscillating gradient spin echo (OGSE) methods have the potential to distinguish effects on restriction at much shorter time and length scales. Both PGSE and OGSE methods have been studied numerically by simulating diffusion in a three‐dimensional, multicompartment tissue model. The results show that conventional measurements with the PGSE method cannot selectively probe variations over short length scales and, therefore, are relatively insensitive to intracellular structure, whereas results using OGSE methods at moderate gradient frequencies are affected by variations in cell nuclear sizes and can distinguish tissues that differ only over subcellular length scales. This additional sensitivity suggests that OGSE imaging may have significant advantages over conventional PGSE methods for characterizing tumors. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Acoustic measures of vocal stability during different speech tasks in young women using oral contraceptives: a retrospective study

Objectives To compare objective voice measures of vocal stability during different speech tasks in women taking oral contraceptives to those in women not taking oral contraceptives. Methods Voice recordings obtained from 28 women, aged 20-30 years old, were used for the study. Eighteen of the women were taking some form of oral contraception at the time of the recording (OC women); ten women were not taking any oral contraceptive medication (NOC women). Measures related to pitch, vocal stability, and loudness were obtained from sustained vowel and paragraph reading tasks. Results The OC women demonstrated significantly higher pitch levels but lower values related to measures of vocal stability. Conclusions The use of oral contraceptives appears to exert a positive influence upon vocal fold function. Women taking oral contraceptives demonstrate higher pitch levels and greater stability during phonation than do women not taking oral contraceptives. This improvement in vocal function is contributed to the more stable hormonal environment that occurs with the use of oral contraceptives.     

Subvastus approach for total knee arthroplasty

The indications for the subvastus approach in total knee arthroplasty are the same for a medial parapatellar approach in the appropriately selected patient. The subvastus approach does not violate the quadriceps mechanism, reduces the need for lateral retinacular release, preserves the patella blood supply, and, with our modifications, can be used in most cases.     

Osteomyelitis: detection with US

To evaluate the role of ultrasound (US) in the detection of osteomyelitis, the authors prospectively studied 48 patients clinically suspected of having osteomyelitis. A sonographic diagnosis was made if fluid was seen directly in contact with bone, without intervening soft tissues. Twelve of the 48 patients were subsequently found to have osteomyelitis. In 10 of them, US demonstrated abnormal fluid adjacent to the bone. This fluid was thought to represent an inflammatory exudate dissecting in a subperiosteal and/or extraperiosteal location. Eight of the 48 patients had soft-tissue fluid collections. The rest of the patients either had no abnormalities or had cellulitis. The authors conclude that US can be useful in the detection of osteomyelitis.     

Magnetic nanoparticles for imaging dendritic cells

We report the development of superparamagnetic iron oxide (SPIOs) nanoparticles and investigate the migration of SPIO‐labeled dendritic cells (DCs) in a syngeneic mouse model using magnetic resonance (MR) imaging. The size of the dextran‐coated SPIO is roughly 30 nm, and the DCs are capable of independent uptake of these particles, although not at levels comparable to particle uptake in the presence of a transfecting reagent. On average, with the assistance of polylysine, the particles were efficiently delivered inside DCs within one hour of incubation. The SPIO particles occupy approximately 0.35% of cell surface and are equivalent to 34.6 pg of iron per cell. In vivo imaging demonstrated that the labeled cells migrated from the injection site in the footpad to the corresponding popliteal lymph node. The homing of labeled cells in the lymph nodes resulted in a signal drop of up to 79%. Furthermore, labeling DCs with SPIO particles did not compromise cell function, we demonstrated that SPIO‐enhanced MR imaging can be used to track the migration of DCs effectively in vivo. Magn Reson Med 63:1383–1390, 2010. © 2010 Wiley‐Liss, Inc.     

Quantitative magnetization transfer imaging via selective inversion recovery with short repetition times.

Quantitative magnetization transfer imaging (qMTI) methods are able to estimate fundamental sample parameters, such as the relative size of the solid-like macromolecular proton pool and the spin exchange rate between this pool and the directly measured free water protons. One such method is selective inversion recovery (SIR), in which the free water protons are selectively inverted and the signal is fit to a biexponential function of the inversion time (TI). SIR uses only low-power pulses and requires no separate RF (B1) or static field (B0) field maps, and the analysis is largely independent of the macromolecular pool lineshape. These are all advantages over steady-state off-resonance saturation qMTI methods. However, up to now, SIR has been implemented only with repetition times TR>T1. This paper describes a modification of SIR with smaller TR values and a greater signal-to-noise ratio (SNR) efficiency.