Release of lymphotoxin by control and chemical carcinogen-treated lymphocyte cultures derived from black healthy subjects and cancer patients

In an age-adjusted comparison with white men, black men have a significantly higher increase in esophageal and other types of cancer associated with environmental causes. The basis of this increase in cancer rates in blacks over the last two decades is unknown. Since cancer patients generally show an impairment in cell-mediated immune (CMI) functions, we measured certain CMI reactions in cultured lymphocytes derived from black healthy subjects and cancer patients. We also determined the levels of aryl hydrocarbon hydroxylase (AHH) induced in these lymphocytes. AHH catalyzes the activation of polycyclic aromatic hydrocarbons (PAH) to intermediates which might alter CMI functions.     

The mouse Mid1 gene: implications for the pathogenesis of Opitz syndrome and the evolution of the mammalian pseudoautosomal region

We have recently reported isolation of the gene responsible for X- linked Opitz G/BBB syndrome, a defect of midline development. MID1 is located on the distal short arm of the human X chromosome (Xp22. 3) and encodes a novel member of the B box family of zinc finger proteins. We have now cloned the murine homolog of MID1 and performed preliminary expression studies during development. Mid1 expression in undifferentiated cells in the central nervous, gastrointestinal and urogenital systems suggests that abnormal cell proliferation may underlie the defect in midline development characteristic of Opitz syndrome. We have also found that Mid1 is located within the mouse pseudoautosomal region (PAR) in Mus musculus , while it seems to be X- specific in Mus spretus. Therefore, Mid1 is likely to be a recent acquisition of the M. musculus PAR. Genetic and FISH analyses also demonstrated a high frequency of unequal crossovers in the murine PAR, creating spontaneous deletion/duplication events involving Mid1. These data provide evidence for the first time that genetic instability of the PAR may affect functionally important genes. In addition, we show that MID1 is the first example of a gene subject to X-inactivation in man while escaping it in mouse. These data contribute to a better understanding of the molecular content and evolution of the rodent PAR.      

Effects of a viral laryngotracheitis on the epithelial barrier of chicken airways

The effects of a virus infection on the barrier function of tracheal epithelium were compared to the effects of a chemical agent (methacholine) which selectively increases membrane permeability, and both were compared to controls. The disruption of the airway epithelium induced by the virus infection caused an increased permeation of horseradish peroxidase (HRP) through this barrier. Methacholine enhanced HRP uptake from the airway lumen to the blood as compared to controls. Visualization of HRP in the tracheal epithelium by transmission electron microscopy correlated with the radioimmunoassay measurements in the blood. Serial anti-HRP antibody titers were measured by a competitive binding technique. The antigen permeation induced by methacholine was associated with an enhanced anti-HRP antibody production. The larger increase in antigen permeation seen with the viral infection was associated with depressed anti-HRP titers. It was concluded that viral disruption of the airway epithelial barrier may contribute to an increased uptake of orally inhaled antigens. The relationship, however, between the increased antigen penetration consequent to the viral infection and the development of allergy remains unclear.     

Organotypic culture of embryonic electromotor system tissues from Torpedo marmorata

An explant culture system has been used to study the electric organ and electric lobe tissues of Torpedo marmorata at different stages during the development of the electromotor system.The myotubes in tissue expiants, taken from the electric organ primordia of 33–38 mm body-length embryos prior to electrocyte differentiation, contract spontaneously on explantation and have electrogenic membranes. The myotubes subsequently lose these properties in vitro and can differentiate in the absence of neural tissue into immature electrocytes which have morphologically characteristic postsynaptic membranes.Isolated expiants of differentiated electric organ tissue from 60–100 mm body-length embryos can be maintained for 3 to 4 weeks in vitro but cellular outgrowth is minimal. In contrast, a rapid, dense outgrowth of cells and a subsequent regeneration of myotubes occurs when differentiated electric organ explants are co-cultured with electric lobe tissue from embryos of the same stage. Cellular outgrowth from differentiated electric-organ tissue expiants can be stimulated by spinal cord, medulla, cerebellum and heart tissues but a subsequent regeneration of myotubes has not been observed. Myotube regeneration in the presence of electric lobe tissue is maximal with tissue from 60–80 mm body-length embryos. The myotubes that regenerate from differentiated electric organ expiants have not been observed to differentiate into electrocytes.Neuritic outgrowth in vitro occurs with electric lobe tissue taken at two different embryonic stages. The first stage corresponds to a period when most of the neuroepithelial cells in the lobe anlagen are withdrawing from the mitotic cycle and projecting axons into the branchial arches. The second, later stage is when the electromotorneurones are normally generating axon collaterals that are invading the interelectrocyte space of electrocyte columns. Maximum neuritic outgrowth at this second, later stage is obtained with tissue from 60–80 mm body-length embryos. Although neuritic invasion of electrocyte column expiants can be obtained in electric organ—electric lobe co-cultures at this later stage, synapses similar to those observed during the early stages of synaptogenesis in the electric organs in vivo have not been observed in vitro.     

Phylogeny and sequence variability of the Sarcocystis singaporensis Zaman and Colley, (1975) 1976 ssrDNA

The coccidium Sarcocystis singaporensis (Apicomplexa: Sarcocystidae) is a cyst-forming parasite with potential as a biological agent for the control of wild populations of rodents in non-native environments. Phylogenetic analysis based on the ssrDNA supports S. singaporensisisolates as a sister species to sarcosporidians transmitted between snakes and rodents but an association with the carnivore-ruminant Sarcocystis spp. could not be rejected by likelihood ratio tests. Four complete and six partial ssrDNA sequences representing this species are monophyletic in any tree reconstruction method; however, they possess very high pairwise distances of up to 0.053. The obtained sequences suggest the probable existence of at least two divergent paralogous ssrDNAs. Moreover, our results support the co-evolution of lsrDNA and ssrDNA in S. singaporensis. The utility of coccidian lsrDNA and ssrDNA for evolutionary studies and their abundance in the primary nucleotide databases is discussed.     

Does support surface coefficient of friction influence postural dynamics and isometric force productions of the upper extremities performed by seated subjects?

The purpose of this study is to determine if increasing the potential risk of slipping on support surface materials decreases postural dynamics and task performance. Seated subjects were asked to exert maximum horizontal two-handed isometric pushes as quickly as possible on a dynamometric bar. Reaction forces exerted at seat (Rxs and Rzs) and footrest (Rxf and Rzf) were measured using force sensors. A dynamometric bar measured horizontal push force (Fx). Global adherence ratio (micro) was calculated. Three support surface materials, characterised by different coefficients of friction, were tested. The same surfaces were placed on the seat and the footrest during a series of pushes. It was shown that the different support surfaces significantly influence Fx, Rxs, Rzs, Rzf and micro maximum values obtained at the end of the push. Even when the instructions given to the subject are to produce a maximum push, the maximum horizontal force applied to the bar differs according to the support surface material. Dynamic postural adjustments are influenced by characteristics of slipperiness of support surfaces. The coefficient of friction contributes an essential element to the program of postural dynamics, which in turn modulates the task performance. During brief isometric pushes, seated subjects have the capacity to control the potential risk of slipping.     

Nucleotide sequence of the geminivirus chloris striate mosaic virus

The genome of chloris striate mosaic virus (CSMV) comprises a single circular DNA as determined by analyses on virion single-stranded (ss) DNA and virus-specific covalently closed circular (ccc) DNA isolated from infected plants. The nucleotide sequence of CSMV DNA was determined from cccDNA and the data were accommodated into one DNA circle of 2750 nucleotides. Comparison of the nucleotide sequence with those of maize streak virus (MSV), wheat dwarf virus (WDV), and digitaria streak virus (DSV) showed 49, 47, and 48% DNA homology, respectively. The sequence has four potential open reading frames for proteins of greater than 10,000 mol wt, two in the viral (+) sense and two in the complementary (-) sense. Three of these potential coding regions have homologous counterparts, by comparison of the amino acid sequences, among the open reading frames reported for MSV, WDV, and DSV. CSMV encapasidates primer molecules able to prime the synthesis in vitro of a complementary strand to virion DNA, initiating this reaction at one site on the genome. The CSMV primer comprising approximately 88 nucleotides was located within the smaller of two intergenic or noncoding regions.