Origin of hematopoietic progenitors during embryogenesis

It has been widely accepted that hematopoietic and endothelial cell lineages diverge from a common progenitor referred to as the hemangioblast. Recently, analyses of the potential of progenitor cells purified from mouse embryos as well as embryonic stem cells differentiating in vitro resolved intermediate stages between mesodermal cells and committed precursors for hematopoietic and endothelial cell lineages. There are two distinct hematopoietic cell lineages which have different origins, i.e., primitive hematopoietic lineage derived from mesoderm or hemangioblasts and definitive hematopoietic lineage derived from endothelial cells. The endothelium is suggested to provide a milieu in which the definitive hematopoietic lineage acquires multiple potentials.     

Use of modified resistogram to type Candida albicans isolated from cases of vaginitis and from faeces in the same geographical area.

Ninety strains of Candida albicans were isolated from vaginal swabs taken by general practitioners from cases of vaginal candidosis. One hundred and nine strains were also isolated from 300 specimens of faeces received from outpatients living in the same geographical area. These strains were typed using a modification of the resistotyping method. We were unable to find any significant differences between the two populations of strains. This suggests that no particular resistotype has an increased ability to cause vaginitis.     

Effect of lymphoid Leukosis virus on performance of layer hens and the identification of infected chickens by tests on Meconia

The effect of subclinical infection with lymphoid leukosis virus (LLV) on the productivity traits of layer hens was investigated. In hens that shed gs-antigen of LLV to albumen, onset of sexual maturity was delayed by a mean of 11 days and the number of eggs laid was reduced -by 68 per hen up to 75 weeks of age. Shedding hens laid on average 2 g lighter eggs and of lesser specific gravity. Thirty-four % less chickens were obtained in the reproduction programmes from LLV-shedders in comparison with non-shedders. LLV had no significant effect on fertility and hatchability. Reduced egg-related performance was only directly related to LLV-shedding and dams' shedding status had no effect on the egg-related performance of their LLV-free progeny. Dams' shedding status, however, correlated with higher mortality (10% higher) among their progeny. The percentage of non-layers was also higher in progeny of LLV-shedders. Meconia were highly suitable samples for identifying both transmitting dams and infected chickens but only if the test for infectious virus was performed. ELISA on meconia was less reliable than the test for virus and therefore is not recommended for the detection of residual of infected chickens in the flocks selected for reduced gs-antigen shedding.     

Concentration and turnover of intraperitoneal hyaluronan during inflammation

Aseptic peritonitis was induced in rabbits by intraperitoneal injection of irritating agents, mainly starch suspensions. The inflammatory response was followed in the peritoneal lavage fluid by cell counts (average increase about 800-fold the first day) and hyaluronan concentration (average increase about 200-fold on the second and third days). The turnover rate of hyaluronan was studied by injecting tritium-labeled hyaluronan intraperitoneally and by following the appearance of tritiated water in serum. In control animals given trace amounts of hyaluronan, half-lives of 1–14 h were recorded. When the labeled polysaccharide had been mixed with 10 mg/ml of unlabeled hyaluronan, the half-life was approximately one day. Rabbits with ongoing peritonitis exhibited half-lives between 1 and 16 h. It was concluded that there was a large individual variation in uptake kinetics, that the removal process could be receptor mediated, and that the increase in intraperitoneal hyaluronan in peritonitis mainly was due to an increased production of the polysaccharide rather than a decreased rate of removal.     

Airway eosinophilia and expression of interleukin-5 protein in asthma and in exacerbations of chronic bronchitis

Background An increased nutnber of eosinophils in the bronchial mucosa has been demonstrated both in asthma and in exacerbations of chronic bronchitis. Oiyective To investigate whether the airway eosinophilia present in asthma and in chronic bronchitis during exacerbations is associated with interleukin (IL)-5 protein expression in the bronchial mucosa. Methods We obtained bronchial biopsies in 18 subjects with asthma (four intrinsic, seven extrinsic and seven occupational) and in II subjects with chronic bronchitis examined during an exacerbation. The findings were compared wilh those of bronchial biopsies from 10 subjects with chronic bronchitis examined under baseline conditions and from seven normal subjects, taken as controls. By immunohistochemistry, we assessed the expression of IL-5 protein and the number of eosinophils (EG2), mast cells ftryptase), and T-lymphocytes (CD3) in the submucosa. Results As compared with controls, the number of eosinophils was increased to a similar degree in both asthma (P < 0.001) and in exacerbations of ehronic bronchitis (P < 0.001). whereas the number of I L-5 immunopositive cells was increased significantly only in asthma (P < 0.01). No diflerences were observed in the number of tnast cells and T-lymphocytes between the four groups of subjects examined. Conciusions This study shows that the degree of airway eosinophilia is similar in asthma and in exacerbations of ehronic bronchitis, but only in asthma is it associated with an increased expression of I L-5 protein in the bronchial tnucosa.     

Fine-needle aspiration of pancreatic extramedullary plasmacytoma: Possible confusion with islet cell tumor

We report two cases of extramedullary plasmacytoma (EMP) of the pancreas, diagnosed by fine-needle aspiration (FNA). Plasmacytoma of the pancreas is a rare neoplasm with only 12 cases recorded in the literature. Because of its scarcity and the cytomorphologic similarity between plasma cells and endocrine cells, EMP of the pancreas may be confused with neuroendocrine (islet cell) tumors of the pancreas. Immunohistochemical staining for light chain and/or neuroendocrine markers will prevent diagnostic error when interpreting plasmacytoid neoplasms of any site susceptible to endocrine tumors, including the pancreas. © 1994 Wiley-Liss, Inc.     

A new physical assay method for tobacco mosaic virus using a radioactive virus recovery standard and the first derivative of the ultraviolet absorption spectrum

A new physical assay method for tobacco mosaic virus is described which incorporates two improvements on previous procedures. Losses of up to 75% of virus during extraction are corrected by adding a trace of radioactive virus to leaf samples before homogenization, and determining percentage recovery of radioactivity in final virus preparations. Estimation of virus concentration in partially purified preparations is from the first derivative (dA/d lambda) of the ultraviolet absorption spectrum, using a pronounced signal from the tryptophan fine-structure absorption band at 285-293 nm. This method is highly insensitive to ultraviolet-absorbing contaminants, which cause errors and increase variation between replicates, when estimation of virus concentration is by normal measurement of ultraviolet absorption (A260). The method can be applied to at least some other viruses.     

Population study of T cell receptor V beta gene usage in peripheral blood lymphocytes: differences in ethnic groups.

The T cell receptor (TCR) V beta repertoire in peripheral blood lymphocytes (PBL) of a large number of healthy individuals was analysed by quantifying V beta-specific mRNA using the method of anchored multiprimer DNA amplification and a reverse dot blot assay. Among 16 V beta gene families examined, particular V beta genes were noted to be unequally expressed in the PBL of 70 healthy donors. The frequently used genes belong to the V beta 4, 5, 6, 8 and 13 (12) families, while V beta 1, 9 and 15 were the least frequently used gene families. This bias in gene usage was observed in all individuals. Marked deviation from the mean percentage usage was noted for some V beta genes in individuals when their PBL were examined serially, but the common pattern of biased usage was not grossly distorted. When the TCR repertoire of different ethnic groups was examined, a lower mean frequency of V beta 3.2 was seen in the repertoire of 19 Caucasians compared with 25 age-matched Samoans (P < 0.003). Conversely, the expression of V beta 5.1 and V beta 5.3 was higher in Caucasians than in 51 age-matched Polynesians (Maoris and Samoans, P < 0.003). Considering the 20% co-efficient of variation in the estimate of V beta gene usage, our data from 70 unrelated individuals suggest that in PBL, individual variations in the TCR repertoire were superimposed upon a common biased usage of V beta genes in the general population.     

Differential expression of stem cell mobilization-associated molecules on multi-lineage cells from adipose tissue and bone marrow

Our laboratory has characterized a population of stromal cells obtained from adipose tissue termed processed lipoaspirate cells (PLAs). PLAs, like bone-marrow derived mesenchymal stem cells (BM-MSCs), have the capacity to differentiate along the adipogenic, osteogenic, chondrogenic, and myogenic lineages, In order to better characterize these two multi-lineage populations, we examined the surface phenotype of both bone marrow and adipose tissue-derived cells from five patients undergoing surgery. PLA and BM-MSC cells were isolated, subcultivated, and evaluated for cell surface marker expression using flow cytometry. PLA and BM-MSC cells both expressed CD13, CD29, CD44, CD90, CD105, SH-3, and STRO-1. Differences in expression were noted for cell adhesion molecules CD49d (Integrin alpha4), CD54 (ICAM-1), CD34, and CD106 (VCAM-1). While markedly similar, the surface phenotypes of PLA and BM-MSC cells are distinct for several cell adhesion molecules implicated in hematopoietic stem cell homing, mobilization, and proliferation.