The role of hemagglutinins in the midgut extracts of two lines of Aedes aegypti in their susceptibility to Dengue-2 virus

Hemagglutinin activity (HA) was studied in the midgut extracts from highly (h) and lowly susceptible strains of Aedes aegypti mosquitoes to Dengue-2 virus (DEN-2). HA in the midgut extracts from these two isofemale strains of mosquitoes was high in as compared to (h) mosquitoes. HA was found to be higher with chicken red blood cells (RBCs) than with rabbit and human RBCs of O group. Larval midgut extracts showed higher activity than those from adult female mosquitoes. Exposure of midgut extracts to 100 degrees C for 10 mins destroyed the activity. The activity was observed between pH 6 and pH 10. HA in midgut extracts was also studied using twenty different carbohydrates; five of them showed an inhibition of HA. The inhibitory carbohydrates, when incorporated into DEN-2-infected bloodmeal, showed a reduction in the susceptibility of mosquitoes to the virus as compared to the control ones fed on the virus alone. Similarly, when these carbohydrates were incorporated in the DEN-2-infected inoculum, the inoculated mosquitoes showed a reduction in the susceptibility to the virus. HA in the virus-infected midgut extracts was higher than that in the uninfected controls. These results suggest that the presence of HA in the midgut may be one of the factors that affect the susceptibility of Ae. aegypti mosquitoes to DEN-2.     

Ring chromosome 8 syndrome: further characterization

We describe two de novo cases of extra r(8) confirmed by fluorescent in situ hybridization (FISH). Based on these two and eight additional cases of extra r(8) confirmed by FISH, the phenotype is better documented. One of our patients had minor facial anomalies, near-normal growth, and neurological development. She had a ring in each cell analyzed. The second had minor craniofacial anomalies and growth and mental retardation. He had a small or double-sized ring in each cell. The phenotype of these 10 cases ranges from almost normal in an adult with 10% mosaicism to variable degrees of minor anomalies, growth retardation, and mental retardation overlapping the mosaic +8 syndrome.     

Distinct types of T-cell help for the induction of a humoral immune response to Streptococcus pneumoniae

Studies have indicated that purified soluble polysaccharide antigens can elicit T cell-independent Ig responses in vivo, although these responses can be modulated by T cells in a noncognate manner. Relatively little is known, however, concerning the parameters that regulate polysaccharide-specific, as well as protein-specific, Ig isotype responses to an intact extracellular bacterium. Using the murine in vivo humoral response to intact Streptococcus pneumoniae as a model it can be shown that CD4+ T-cell receptor alphabeta+ T cells deliver help for both polysaccharide- and protein-specific Ig responses. However, these responses differ fundamentally in their mechanism of action.     

Evaluation of EDTA and fish skin extract in primary culture of fish liver cells

The isolation, primary culture and attachment of liver cells to the substratum from a tropical catfish (Heteropneustes fossilis) using ethylenediaminetetraacetic acid (EDTA) as isolating agent of liver cells and skin extract (SE) from fish as attachment substrate for the primary culture of liver cells has been standardised. A suitable temperature for such cultures has also been determined. Attachment efficiency of the liver cells in culture and their intracellular lactate dehydrogenase (LDH) activity have been taken as parameters for characterization of the primary culture. Disaggregation of liver cells with EDTA is very potent to isolate substantial rumber of cells from the liver of H. fossilis. An ideal concentration of EDTA for liver cell isolation has been standardized. Matrix prepared from carp and catfish skin at different pH (2.0, 4.0, 6.0 and 8.0) were also evaluated for liver cell culture by considering the attachment efficiency of the cells over the substratum as well as retention of intracellular LDH enzyme after 48 hours of seeding. Matrix of carp skin was compared with that of catfish as suitable substrate for primary culture of fish liver cells. It has been found that the SE prepared at pH 4.0, both from carp and catfish skin, performed better than those at other pHs. At the same time, the matrix of carp skin was found to be better than that of catfish skin. Cultures were incubated separately at 17 and 23 °C in air atmosphere. Incubation temperature at 23 °C was found to be more suitable than that at 17 °C. The percent of detached/unattached cells showed only marginal variation between two temperatures but LDH-activity recorded drastic reduction (between 50 to 75%) depending upon the pH of the matrix during preparation. Our finding establishes despensibility of enzyme (collagenase/trypsin) for cell isolation in catfish. Our studies also exhibit that carp skin extract performs better than catfish skin extract in terms of attachment efficiency as well as intracellular LDH activity. This study indicates that no species/generic barrier exists in matrix between catfish and carp.     

Ultrastructural comparison between regenerating and developing hindlimbs of Xenopus laevis tadpoles

Hindlimbs of Xenopus laevis tadpoles at stages 50 to 55 of embryonic development were amputated in order to study the fine structure associated with ontogenetic decline in regenerative ability of this anuran. Regenerating hindlimbs were compared with their contralateral developing limb so as to determine the similarities and differences in ectodermal-mesenchymal ultrastructural relationships in these systems. Prior to stage 53, mesenchymal cells in regenerating limbs, as well as mesenchyme cells in developing limbs appear undifferentiated; the cells are not visibly different. However, at stage 54 muscle and cartilage differentiation in the developing foot is distinct. Furthermore, in all larvae with regenerates at stages 50 to 52 the basal lamina is not evident subjacent to the apical tip of the epithelium which covers the amputation surface. A distinct basal lamina is present, however, beneath the epidermis in all embryonic limbs examined, including the apical tip, as well as in regenerates of stages 53 to 55 tadpoles. Also, a greater apical accumulation of extracellular matrix (ECM) and organized collagen is observed among the mesenchymal cells in regenerates of stages 53 to 55 tadpoles, and among the mesenchyme cells in developing limbs of stages 50 to 55, compared with pre-stage 53 regenerates. In cases in which an embryonic limb bud is composed of relatively undifferentiated cells (stages 50 to 52), events following amputation result in the complete regeneration of a limb. However, when amputated embryonic limbs contain differentiating tissues, (e.g., muscle and cartilage) only selective tissues undergo regeneration resulting in malformed (heteromorphic) regenerates.(ABSTRACT TRUNCATED AT 250 WORDS)     

A unique, complex variant philadelphia chromosome translocation in a patient with typical chronic myelogenous leukemia

The Philadelphia (Ph) chromosome [der(22) t(9;22)(q34;q11)] is the characteristic chromosomal abnormality found in chronic myelogenous leukemia (CML). This chromosome has been reported in patients with other chromosomal abnormalities. In this study, we describe a patient with hematologically typical chronic-phase CML with an unusual and complex translocation involving chromosomes 9, 11, and 22. These complex translocations were identified by G-banded conventional cytogenetics and confirmed by fluorescence in situ hybridization (FISH) using whole chromosome painting probes (wcp). To the best of our knowledge, these are unique translocations involving the short and the long arms of chromosome 9 in 4 different translocations with the short arm of chromosome 11 and the long arm of chromosome 22.     

Inhibition of heparin/protamine complex-induced complement activation by Compstatin in baboons

Complement activation products are major components of the inflammatory response induced by cardiac surgery and cardiopulmonary bypass which contribute to postoperative organ dysfunction, fluid accumulation, and morbidity. Activation of the complement system occurs during extracorporeal circulation, during reperfusion of ischemic tissue, and after the formation of heparin-protamine complexes. In this study we examine the efficacy of Compstatin, a recently discovered peptide inhibitor of complement, in preventing heparin/protamine-induced complement activation in baboons. The study was performed in baboons because Compstatin binds to baboon C3 and is resistant to proteolytic cleavage in baboon blood (similar to humans); Compstatin inhibits only the activation of primates' complement system. After testing various doses and administration regimens, Compstatin produced complete inhibition at a total dose of 21 mg/kg when given as a combination of bolus injection and infusion. Compstatin completely inhibited in vivo heparin/protamine-induced complement activation without adverse effects on heart rate or systemic arterial, central venous, and pulmonary arterial pressures. This study indicates that Compstatin is a safe and effective complement inhibitor that has the potential to prevent complement activation during and after clinical cardiac surgery. Furthermore, Compstatin can serve as the prototype for designing an orally administrated drug.