Imaging the femoral cortex: thickness, density and mass from clinical CT.

There is growing evidence that focal thinning of cortical bone in the proximal femur may predispose a hip to fracture. Detecting such defects in clinical CT is challenging, since cortices may be significantly thinner than the imaging system's point spread function. We recently proposed a model-fitting technique to measure sub-millimetre cortices, an ill-posed problem which was regularized by assuming a specific, fixed value for the cortical density. In this paper, we develop the work further by proposing and evaluating a more rigorous method for estimating the constant cortical density, and extend the paradigm to encompass the mapping of cortical mass (mineral mg/cm(2)) in addition to thickness. Density, thickness and mass estimates are evaluated on sixteen cadaveric femurs, with high resolution measurements from a micro-CT scanner providing the gold standard. The results demonstrate robust, accurate measurement of peak cortical density and cortical mass. Cortical thickness errors are confined to regions of thin cortex and are bounded by the extent to which the local density deviates from the peak, averaging 20% for 0.5mm cortex.

Systematic misregistration and the statistical analysis of surface data.

Spatial normalisation is a key element of statistical parametric mapping and related techniques for analysing cohort statistics on voxel arrays and surfaces. The normalisation process involves aligning each individual specimen to a template using some sort of registration algorithm. Any misregistration will result in data being mapped onto the template at the wrong location. At best, this will introduce spatial imprecision into the subsequent statistical analysis. At worst, when the misregistration varies systematically with a covariate of interest, it may lead to false statistical inference. Since misregistration generally depends on the specimen's shape, we investigate here the effect of allowing for shape as a confound in the statistical analysis, with shape represented by the dominant modes of variation observed in the cohort. In a series of experiments on synthetic surface data, we demonstrate how allowing for shape can reveal true effects that were previously masked by systematic misregistration, and also guard against misinterpreting systematic misregistration as a true effect. We introduce some heuristics for disentangling misregistration effects from true effects, and demonstrate the approach's practical utility in a case study of the cortical bone distribution in 268 human femurs.

Onychostoma virgulatum, a new species of cyprinid fish (Pisces: Teleostei) from southern Anhui Province, South China

Onychostoma virgulatum, new species, is described from the Qiupu River, a tributary on the Southern bank of the lower Yangtze River at Shitai County, southern Anhui Province, South China. It shares with O. fusiforme and O. meridionale the presence of a longitudinal dark brown stripe extending along the lateral line, a character separating them from all other congeners of the moderate-mouth group diagnosed by having a slightly arched or nearly transverse mouth opening (with the extremities slightly curved posteriorly), its width being equal to or slightly less than the width of head at this same point, and a short postlabial groove extending along half of the length of the lateral margin of the lower jaw. Onychostoma virgulatum differs from both in the presence of two pairs of barbels in adults, from O. fusiforme in the body depth, caudal-peduncle depth, and position of pelvic and anal fins, and from O. meridionale in the structure of the last simple dorsal-fin ray.

Age and growth of Schizopygopsis younghusbandi younghusbandi in the Yarlung Zangbo River in Tibet, China

Schizopygopsis younghusbandi younghusbandi is an endemic species whose distribution is restricted to the middle reaches of the Yarlung Zangbo River, being one of the most important commercial fishes in this area. Age and growth of 606 specimens captured between October 2002 and April 2005 were studied. The range in standard length (L) was 65.7-387.3 mm and total weight (W) was 3.3-772.0 g. The relationship between L and W was W=0.000909L(2.2493) for males and W=0.000259L(2.4781) for females. Age, determined from anal scales and lapillus otoliths, ranged from 3 to 18 years. The parameters of von Bertalanffy growth functions, estimated by back-calculated length, were L-infinity = 442.7mm L, k=0.0738 year(-1) and t(0)=-1.4 year for males, and L-infinity = 471.4mm L, k=0.0789 year(-1) and t(0)=0.2 year for females. Males and females exhibited statistically significant differences in growth. chi(2)-test indicated that von Bertalanffy growth functions could well describe the growth of S. y. younghusbandi. The longevities were 39.2 and 38.2 years for males and females, respectively. Growth inflexion points were 10.2 and 12.0 years for males and females, respectively, but 84.8% of the captures were at the smaller ages. So conservation and management schemes for this population should be considered urgently. In addition, we found that populations from the upstream of the Lhasa River, the downstream of the Lhasa River and the middle reaches of the Yarlung Zangbo River showed statistically significant differences in growth patterns.

First description of a novel Weissella species as an opportunistic pathogen for rainbow trout Oncorhynchus mykiss (Walbaum) in China

Six strains of Gram-positive, catalase-negative, non-motile, irregular short rod-shaped Weissella bacteria, with width and length of 0.5-0.6 and 1.2-2.7 mu m were isolated from diseased rainbow trout Oncorhynchus mykiss (Walbaum) in winter of 2007 at a commercial fishery in Jingmen, Hubei province, China. The diseased rainbow trout exhibited hemorrhage in eyes, anal region, intestine and abdomen wall, petechia of liver, some fish with hydrocele in stomach. Six isolates had identical biochemical reactions, phylogenetic analysis of 16S rDNA sequences, amplified ribosomal DNA restriction analysis (ARDRA), enzymatic profile analysis and antimicrobial susceptibility results, indicating as a single clonal outbreak. But all were different from any other validated twelve Weissella species in the term of physiological and biochemical characters. It is indicated that isolates are phylogenetically closer to Weissella halotolerans, Weissella viridescens and Weissella minor on 16S rDNA phylogenetic analysis result, than to W halotolerans and W viridescens on the result of ARDRA study and enzymatic profile analysis. Antimicrobial susceptibility testing was used to scan effective drugs for the therapy of this disease. Experimental infection assays with one isolate were conducted and pathogenicity (by intraperitoneal injection) was demonstrated in rainbow trout O. mykiss (Walbaum) and crucian carp (Carassius auratus gibelio) fingerlings. Because no Weissella was detected in fish feedstuffs and pond water, the source of this pathogen remains unknown, and Weissella isolates were regarded as an opportunistic pathogen for rainbow trout. This is the first report of Weissella strains which can cause disease of cultured fish in the world. (C) 2009 Elsevier B.V. All rights reserved.

Pseudobagrus fui Miao, a valid bagrid species from the Yangtze River drainage, South China (Teleostei: Bagridae)

Pseudobagrus fui Miao is a valid bagrid species that can be separated from all its congeners in having 27-33 anal-fin rays. Among the species of Pseudobagrus, it forms part of a group of approximately 20 species putatively characterized by having a smooth anterior margin of the pectoral-fin spine and short maxillary barbels not extending to the base of the pectoral-fin spine. Pseudobagrus fui, together with P. nitidus and P. vachelli, can be differentiated from all other fork-tailed species of this group by having no fewer than 20 branched anal-fin rays, the posterior end of the anal-fin base posterior to the vertical through the posterior end of the adipose-fin base, and anal-fin base longer than the adipose-fin base. It further differs from P. nitidus in having a gas bladder without beaded lateral and posterior margins, and from P. vachelli in having short maxillary barbels not extending to the base of the pectoral-fin spine. Pseudobagrus fui is currently known from the main stream of the upper Yangtze River and its tributaries, the Min River, Jialing River, Tuo River, Wu River and Chishui River in Sichuan Province, Guizhou Province, and the Chongqing City. The identity and nomenclature of Pseudobagrus nitidus is also discussed.

Metzia longinasus, a new cyprinid species (Teleostei: Cypriniformes) from the Pearl River drainage in Guangxi Province, South China

Metzia longinasus, a new cultrine cyprinid species from the Hongshui-He River of the Pearl River drainage in Guangxi Province, southern China, is described here. It can be distinguished from all other congeners by having a combination of the following characters: a superior mouth, 43 or 44 lateral-line scales, a long head (length 27.2-30.8% of standard length), a long snout (length 31.7-37.0% of head length), 10 or 11 branched anal-fin rays, and no longitudinal black band extending along each side of body from the extremity of the gill opening to caudal-fin base.

Triplophysa waisihani, a new species of nemacheiline loach from Northwest China (Pisces: Balitoridae)

Triplophysa waisihani, a new species of nemacheiline loach, is described from the Kax River, a tributary of the Ili River drainage in Xinjiang-Uighur Autonomous Region of Northwest China. It can be assigned to the T. labiata species group characterized by having widely separated anterior and posterior nostrils and no breeding tubercles on the sides of the head. Triplophysa waisihani resembles T. labiata and T. herzensteini, but differs from both in cephalic sensory-canal pattern and the structure of the gas bladder; from T. labiata in the structure of the pelvic girdle and absence or presence of the fourth basibranchial; and from T. herzensteini in the shape of the anal fin.

Pseudobagrus brachyrhabdion, a new catfish (Teleostei : Bagridae) from the middle Yangtze River drainage, South China

Pseudobagrus brachyrhabdion sp. nov., from the Yuan Jiang and Xiang Jiang of the middle Yangtze River drainage in Hunan and Guizhou Provinces, South China, is described herein. It is distinguished from all other Pseudobagrus species with a truncate or slightly emarginated caudal fin by an unique combination of the following characters: supraoccipital plate and nuchal plate broadly interspaced and covered with skin; nasal barbels only at most reaching anterior margin of eye; maxillary barbels reaching slightly beyond posterior margin of eye; outer mandibular barbels extending to posterior margin of eye; dorsal fin with a somewhat convex distal margin, origin nearer to pectoral-fin insertion than to pelvic-fin insertion; dorsal-fin spine shorter than pectoral spine, with a somewhat serrated posterior margin; pectoral-fin spine with a smooth anterior margin; anal fin with 20-23 rays, base length 23.8-32.0% of standard length, posterior end of anal-fin base anterior to posterior end of adipose fin base; no longitudinal black band extending along flank; eyes large, diameter 16.3-23.7% of head length; and number of vertebrae 5 + 43-46.

Triplophysa lixianensis, a new nemacheiline loach species (Pisces : Balitoridae) from the upper Yangtze River drainage in Sichuan Province, South China

Triplophysa lixianensis, a new nemacheiline loach species, is described from the Min Jiang of the upper Yangtze River drainage in Sichuan Province, South China. It can be separated from all other species of Triplophysa by having a unique combination of the following characters: posterior chamber of gas bladder greatly reduced or absent; caudal peduncle columnar with a roughly round cross- section at its beginning; anterior edge of lower jaw completely exposed or uncovered by lower lip; intestine short, forming a zigzag loop below stomach; dorsal- fin origin closer to caudal- fin base than to snout tip; pelvic fin inserted anterior to dorsal- fin origin; snout length 50.6 - 57.5 % of head length; eye diameter 12.3 15.4 % of head length; caudal peduncle length 25.1 - 27.1 % of standard length; anal fin with five branched rays; lower lip greatly furrowed with two thick lateral lobes; and body smooth or scaleless.