Magnetic resonance elastography with guided pressure waves

Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.     

Sniff nasal inspiratory pressure: what is the optimal number of sniffs?

Sniff nasal inspiratory pressure (SNIP) measurement is a volitional noninvasive assessment of inspiratory muscle strength. A maximum of 10 sniffs is generally used. The purpose of the present study was to investigate whether the maximum SNIP improved after the tenth sniff. In total, 20 healthy volunteers and 305 patients with various neuromuscular and lung diseases were encouraged to perform 40 and 20 sniffs, respectively. The best SNIP among the first 10 sniffs was lower than the best SNIP among the next 10 sniffs in the healthy volunteers and patients. The SNIP improvement after the twentieth sniff was marginal. In conclusion, a learning effect persists after the tenth sniff. The current authors suggest using 10 additional sniffs when the best result of the first 10 sniffs is slightly below normal, or when sniff nasal inspiratory pressure is used to monitor a progressive decline in inspiratory muscle strength.     

Anticarcinogenic action of diallyl sulfide in hamster buccal pouch and forestomach.

The anticarcinogenic action of the garlic constituent diallyl sulfide (DAS), was examined in the hamster buccal pouch and forestomach. Groups of hamsters were topically treated, for up to 14 weeks, with a 0.5% solution of the buccal pouch and forestomach carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). Prior to, during and after DMBA treatment, groups of hamsters were also treated, on alternate days, with a 1% solution of DAS. In addition to tumor formation, the induction of gamma-glutamyl transpeptidase (gamma GT) buccal pouch epithelial lesions served as an additional presumptive index of in vivo carcinogenesis/anticarcinogenesis. DAS resulted in a significant reduction in buccal pouch tumor frequency, buccal pouch tumor burden, buccal pouch gamma GT lesion frequency and forestomach tumor frequency. In a separate experiment, DAS also reduced the level of autoradiographically quantified unscheduled DNA repair synthesis (UDS) in pieces of hamster buccal pouch concurrently exposed in vitro to the potent buccal pouch carcinogen N-methyl-N-benzylnitrosamine (MBN). This study demonstrates that DAS is an effective anticarcinogenic agent in squamous mucosa of the hamster and suggests novel cost-effective strategies for the rapid identification of tissue-specific anticarcinogens and a quantitative assessment of their efficacy.     

Comparison of 2-dimensional and 3-dimensional acquisition for 18F-FDG PET oncology studies performed on an LSO-based scanner.

Three-dimensional (3D) PET acquisition has the potential to reduce image noise but the advantage of 3D PET for studies outside the brain has not been well established. To compare the performance of 2-dimensional (2D) and 3D acquisition for whole-body (18)F-FDG applications, a series of patient studies were performed using a lutetium oxyorthosilicate (LSO)-based tomograph. METHODS: Comparative 2D and 3D images were acquired for 27 oncology patients using an LSO-based tomograph. Data acquisition (350-650 keV, 6 ns) started 99 +/- 12 min (mean +/- SD) after injection of 624 +/- 76 MBq (18)F-FDG. Bias caused by tracer redistribution and decay was eliminated by acquiring dynamic data over a single-bed position using a protocol that alternated between septa-in and septa-out modes (2D, 3D, 2D, 3D, 2D, 3D). Frames were combined to form 8 statistically independent sinograms: four 2D replicates (105 s) and four 3D replicates (90 s). The different frame durations in 2D and 3D compensated for the different number of overlapping bed positions required for an 85-cm whole-body study. Images were reconstructed with either 2D or fully 3D ordered-subsets expectation maximization (2 iterations and 8 subsets; 2D 6-mm gaussian, 3D 5- and 6-mm gaussian). Image target-to-background ratio was assessed by dividing the lesion maximum by the mean within a neighboring background region. Image noise was assessed by applying background regions of interest to the replicate images and calculating the within-patient coefficient of variation. RESULTS: The difference in target-to-background ratio between the 2D and 3D images, when they were filtered with 6-mm and 5-mm gaussian filters, respectively, was not highly statistically significant (P = 0.16). The mean ratio of 3D to 2D image values was 0.94 with 95% limits of agreement of 0.63-1.41. The within-patient coefficients of variation for the 2D and 3D images were 13% +/- 15% and 9% +/- 10%, respectively (P = 0.0005). CONCLUSION: Under conditions of matched target to-to-background ratios, the 3D mode was found to produce images with significantly less variability than the 2D mode. These data provide support for the use of 3D acquisition with LSO detectors to reduce scan times in whole-body (18)F-FDG applications.     

Expression of collagen and elastic fibers in duct-ligated submandibular glands of mice

Atrophy of salivary glands may occur by ductal obstruction caused by calculus, infection or neoplastic processes, or as consequence of systemic diseases and aging. In the present work, we have used histochemical methods to study the expression of elastic and collagen fibers during experimental atrophy of the submandibular gland of mice. Glandular atrophy was accompanied by a rapid increase in collagen deposition in both septal and intralobular regions. The expression of elastic fibers was not significantly altered during atrophy; a discrete increase of elastic fibers was noted only around ductal structures. The results showed that experimental ductal obstruction is a useful in vivo model to study molecular events that take part in the remodeling of the extracellular matrix during atrophy of salivary glands.     

鲍曼不动杆菌消毒剂——磺胺耐药基因研究

目的了解鲍曼不动杆菌耐消毒剂-磺胺基因（qacE△1-sul1）存在情况。方法自临床分离27株鲍曼不动杆菌，采用聚合酶链反应法检测qacE△1-sul1基因和Ⅰ类整合酶基因（intⅠ1）。结果27株AB菌检测qacE△1-su1Ⅰ基因阳性22株（81-4％），intⅠ1基因阳性23株（85.2％）。qacE△l-su1Ⅰ基因和intⅠ1基因具有相关性。结论我院临床分离的鲍曼不动杆菌qacE△1-sul1基因携带率较高。这和qacE△1-sul1基因与Ⅰ类整合酶基因整合在一起有关。     

Medical abortion in the first trimester: the use of serum hCG and endometrial thickness as markers of completeness.

OBJECTIVE: The combination of mifepristone and misoprostol is an established method for induction of early first trimester abortion, but there is no consensus about the best evaluation of treatment outcome. We assessed endometrial thickness, determined by ultrasound and serum-human chorionic gonadotropin (s-hCG) as markers of successful management. METHODS: Prospective trial involving 255 women, with a gestation of 62 days or less, who were to undergo medical abortion. In addition to our established routines of performing clinical and ultrasound examinations, we also determined the s-hCG level prior to treatment and at follow-up. RESULTS: Of the 255 subjects treated during the study, 20 (7.8%) were lost to follow-up. The overall complete abortion rate was 94.0%. Fourteen subjects required vacuum aspiration, nine of them prior to the scheduled follow-up and five thereafter. None of the pregnancies were ongoing. A decrease of 99% in s-hCG levels was noted in 99% of the women, when levels determined prior to mifepristone intake and those measured 15-71 days post-abortion were compared. CONCLUSION: This study confirms that s-hCG levels drop sharply after medical abortion. To assess the completeness of medical abortion, we recommend that clinical examination to be combined with determination of s-hCG. Ultrasonography should be carried out only when indicated.     

Heterogeneous expression of CD59 on human Purkinje cells

The expression of CD59 and other complement regulators was studied in human cerebellum from 14 individuals with no cerebellar pathology, from one patient with multiple sclerosis (MS) and from two patients with paraneoplastic cerebellar degeneration (PCD). CD59 was present on the Purkinje cells at various levels in eight of the 14 cases with no cerebellar pathology. CD59 was also present on the Purkinje cells of the patient with MS, but not on the scarce remaining Purkinje cells of the two patients with PCD. Other complement regulators (CD35, CD46 and CD55) were not expressed on the Purkinje cells, whereas CD59, CD46 and CD55 were present on the molecular, granulosa and endothelial cells. The results suggest that Purkinje cells not expressing CD59 could be especially prone to complement-mediated damage.