Spatial and functional relationships between air conduits and blood capillaries in the pulmonary gas exchange tissue of adult and developing chickens

The documented data regarding the three-dimensional structure of the air capillaries (ACs), the ultimate sites of gas exchange in the avian lung is contradictory. Further, the mode of gas exchange, described as cross-current has not been clearly elucidated. We studied the temporal and spatial arrangement of the terminal air conduits of the chicken lung and their relationship with the blood capillaries (BCs) in embryos as well as the definitive architecture in adults. Several visualization techniques that included corrosion casting, light microscopy as well as scanning and transmission electron microscopy were used. Two to six infundibulae extend from each atrium and give rise to numerous ACs that spread centrifugally. Majority of the ACs are tubular structures that give off branches, which anastomose with their neighboring cognates. Some ACs have globular shapes and a few are blind-ending tapering tubes. During inauguration, the luminal aspects of the ACs are characterized by numerous microvillus-like microplicae, which are formed during the complex processes of cell attenuation and canalization of the ACs. The parabronchial exchange BCs, initially inaugurated as disorganized meshworks, are reoriented via pillar formation to lie predominantly orthogonal to the long axes of the ACs. The remodeling of the retiform meshworks by intussusceptive angiogenesis essentially accomplishes a cross-current system at the gas exchange interface in the adults, where BCs form ring-like patterns around the ACs, thus establishing a cross-current system. Our findings clarify the mode of gas exchange in the parabronchial mantle and illuminate the basis for the functional efficiency of the avian lung.

Urothelial neoplasms of the urinary bladder occurring in young adult and pediatric patients: a comprehensive review of literature with implications for patient management

Bladder urothelial carcinoma is typically a disease of older individuals and rarely occurs below the age of 40 years. There is debate and uncertainty in the literature regarding the clinicopathologic characteristics of bladder urothelial neoplasms in younger patients compared with older patients, although no consistent age criteria have been used to define "younger" age group categories. Use of the World Health Organization 2004/International Society of Urological Pathology 1998 grading nomenclature and recent molecular studies highlight certain unique features of bladder urothelial neoplasms in young patients, particularly in patients below 20 years of age. In this meta-analysis and review, the clinical, pathologic, and molecular features and risk factors of bladder urothelial neoplasms in patients 40 years or less are presented and analyzed according to decades of presentation. Similar to older patients, bladder urothelial neoplasms in patients 40 years or younger occur more common in male patients, present mainly with gross painless hematuria, and are more commonly located at bladder trigone/ureteral orifices, but in contrast have a greater chance for unifocality. Delay in diagnosis of bladder urothelial neoplasms seems not to be uncommon in younger patients probably because of its relative rarity and the predominance of benign causes of hematuria in this age group causing hesitancy for an aggressive work-up. Most tumors in patients younger than 40 years were low grade. The incidence of low-grade tumors was the lowest in the first 2 decades of life, with incremental increase of the percentage of high-grade tumors with increasing age decades. Classification according to the World Health Organization 2004/International Society of Urological Pathology grading system identified papillary urothelial neoplasms of low malignant potential to be relatively frequent among bladder tumors of young patients particularly in the teenage years. Similar to grade, there was marked predominance of low stage tumors in the first 2 decades of life with gradual inclusion of few higher stage and metastatic tumors in the 2 older decades. Bladder urothelial neoplasms occurring in patients <20 years of age lack or have a much lower incidence of aberrations in chromosome 9, FGFR3, p53, and microsatellite instability and have fewer epigenetic alterations. Tumor recurrence and deaths were infrequent in the first 2 decades and increased gradually in each successive decade, likely influenced by the increased proportion of higher grade and higher stage tumors. Our review of the literature shows that urothelial neoplasms of the bladder occurring in young patients exhibit unique pathologic and molecular features that translate to its more indolent behavior; this distinction is most pronounced in patients <20 years. Our overall inferences have potential implications for choosing appropriate noninvasive diagnostic and surveillance modalities, whenever feasible, and for selecting suitable treatment strategies that factor in quality of life issues vital to younger patients.

The production and composition of rat sebum is unaffected by 3 Gy gamma radiation

The aim of this work was to use metabolomics to evaluate sebum as a source of biomarkers for gamma-radiation exposure in the rat, and potentially in man. Proof of concept of radiation metabolomics was previously demonstrated in both mouse and rat urine, from the radiation dose- and time-dependent excretion of a set of urinary biomarkers.

Quality, size, and composition of pediatric endobronchial biopsies in cystic fibrosis

BACKGROUND: Studies on airway remodeling in children with cystic fibrosis (CF) may be hampered by difficulty in obtaining evaluable endobronchial biopsy specimens because of large amounts of mucus and inflammation in the CF airway. We prospectively assessed how the quality of biopsy specimens obtained from children with CF compare with those from children with other airway diseases. METHODS: Fiberoptic bronchoscopy with endobronchial biopsy was performed in 67 CF children (age range, 0.2 to 16.8 years), 34 children with wheeze/asthma (W/A), and 64 control children with chronic respiratory symptoms. Up to three biopsy specimens were taken and stained with hematoxylin and eosin. Biopsy specimen size and structural composition were quantified using stereology. RESULTS: At least one evaluable biopsy specimen was obtained in 72% of CF children, in 79% of children with W/A, and in 72% of control subjects (difference was not significant). The use of large biopsy forceps (2.0 mm) rather than small biopsy forceps (1.0 mm) [odds ratio (OR), 5.8; 95% confidence interval (CI), 1.1 to 29.8; p = 0.037] and the number of biopsy specimens taken (odds ratio, 2.6; 95% confidence interval, 1.3 to 5.2; p = 0.006) significantly contributed to the success rate. Biopsy size and composition were similar between groups, except that CF children and those patients with W/A had a higher percentage of the biopsy specimen composed of muscle than did control subjects (median 6.2% and 9.7% vs 0.9%, respectively; p = 0.002). CONCLUSIONS: Biopsy size and quality are adequate for the study of airway remodeling in CF children as young as 2 months of age. Researchers should use large forceps when possible and take at least two biopsy specimens per patient. An increased airway smooth muscle content of the airway mucosa may contribute to the pathophysiology of CF lung disease.

Sporadic bloody diarrhoea-associated thrombotic thrombocytopenic purpura-haemolytic uraemic syndrome: an adult and paediatric comparison

Although diarrhoea-associated haemolytic uremic syndrome (HUS) in children is well described, the clinical features of bloody diarrhoea-associated thrombotic thrombocytopenic purpura (TTP)-HUS in adults are not documented. Twenty-one adults, 6.5% of the 322 adults in The Oklahoma TTP-HUS Registry, 1989-2006, have presented with bloody diarrhoea. There were no case clusters. Escherichia coli O157:H7 was identified in five patients, but many patients did not have appropriate studies. The annual incidence was 0.68/10(6), 10-fold less than the incidence of diarrhoea-associated HUS in children in Oklahoma. Two (13%) of 16 patients in whom ADAMTS13 (A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13) was measured had <10% activity. Severe neurological abnormalities (67%) and renal failure (62%) were common; seven patients (33%) died; no survivors have relapsed. Compared to the 38 other Oklahoma Registry patients with ADAMTS13 <10%, frequency of severe neurological abnormalities and death was not different; frequency of renal failure was greater; frequency of relapse was less. Compared to 5999 children with sporadic diarrhoea-associated HUS in published reports, frequency of renal failure and relapse was not different; frequency of severe neurological abnormalities and death was greater (P < 0.05 for all differences). Awareness of the continuous occurrence of sporadic bloody diarrhoea-associated TTP-HUS in adults is important for prompt diagnosis and appropriate management.

The content and composition of lipids in the digital cushion of the bovine claw with respect to age and location--a preliminary report

The pads of the bovine digital cushion, which serves as a shock absorber, have specific anatomical structures to cope with the substantial forces acting within the claw. To gain more information on the lipid composition and content of the pads, horn shoes from 12 slaughtered heifers and cows were removed and different samples of the pads excised with a scalpel. Pad lipids were extracted and the fatty acid composition determined by gas chromatography. Fat from perirenal and subcutaneous adipose tissues served as a comparison. Overall, this fat contained a higher quantity of extracted lipids than that of the claw pads and did not differ between heifers and cows. In contrast, lipid content in the pads was significantly higher in the cows than in the heifers. In both groups, the lipid content of the middle and abaxial pads, which are situated directly under the distal phalanx, was lower than in the pads of the other locations. The lipids in all pads contained >77% monounsaturated fatty acids (MUFA), differing sharply from the adipose tissue with values <51%. Among the polyunsaturated fatty acids (PUFA) a significantly higher proportion of arachidonic acid (AA) was found in the heifer pads than in those of the cows, whereas the proportion of AA was similar in the adipose tissue of all animals. The proportion of AA in the pad lipids also varied between the defined locations with the highest proportion found in locations that showed the lowest lipid content and was related to the age of the animal.

Forest structure and composition of previously selectively logged and non-logged montane forests at Mt. Kilimanjaro

The montane forests of Mount Kilimanjaro in Tanzania have been subjected to a long history of selective logging. However, since 1984 logging of indigenous trees is prohibited. Today, these forests allow us to evaluate the long-term effects of selective logging. We mapped the height and diameter at breast height (DBH) of all trees >10 cm DBH on 10 sites of 0.25 ha. Five sites represent non-logged forests, another five selectively logged forests. We tested whether forests were still visibly affected 30–40 years after selective logging in terms of their forest structure and tree diversity. Additionally we compared tree densities of different species guilds, including disturbance-indicator species, late-successional species and main timber species. Furthermore, we specifically compared the community size distributions of selectively logged and non-logged forests, first across all species and then for the most important timber species, Ocotea usambarensis, alone. 30–40 years after selective logging forests still showed a higher overall stem density, mainly due to higher relative abundances of small trees (<50 cm DBH) in general, and higher densities of small size class stems of late-successional species specifically. For O. usambarensis, the selectively logged sites harboured higher relative abundances of small trees and lower relative abundances of harvestable trees. The higher relative abundance of small O. usambarensis-stems in selectively logged forests appears promising for future forest recovery. Thus, outside protected areas, selective logging may be a sustainable management option if logging cycles are considerably longer than 40 years, enough large source trees remain, and the recruiting O. usambarensis individuals find open space for their establishment.

Ecosystem structure, function, and composition in rangelands are negatively affected by livestock grazing

Reports of positive or neutral effects of grazing on plant species richness have prompted calls for livestock grazing to be used as a tool for managing land for conservation. Grazing effects, however, are likely to vary among different response variables, types, and intensity of grazing, and across abiotic conditions. We aimed to examine how grazing affects ecosystem structure, function, and composition. We compiled a database of 7615 records reporting an effect of grazing by sheep and cattle on 278 biotic and abiotic response variables for published studies across Australia. Using these data, we derived three ecosystem measures based on structure, function, and composition, which were compared against six contrasts of grazing pressure, ranging from low to heavy, two different herbivores (sheep, cattle), and across three different climatic zones. Grazing reduced structure (by 35%), function (24%), and composition (10%). Structure and function (but not composition) declined more when grazed by sheep and cattle together than sheep alone. Grazing reduced plant biomass (40%), animal richness (15%), and plant and animal abundance, and plant and litter cover (25%), but had no effect on plant richness nor soil function. The negative effects of grazing on plant biomass, plant cover, and soil function were more pronounced in drier environments. Grazing effects on plant and animal richness and composition were constant, or even declined, with increasing aridity. Our study represents a comprehensive continental assessment of the implications of grazing for managing Australian rangelands. Grazing effects were largely negative, even at very low levels of grazing. Overall, our results suggest that livestock grazing in Australia is unlikely to produce positive outcomes for ecosystem structure, function, and composition or even as a blanket conservation tool unless reduction in specific response variables is an explicit management objective.