Concentration and detection of hepatitis A virus and rotavirus from shellfish by hybridization tests

A modified polyethylene glycol precipitation method for concentration of virus followed by a new method to recover nucleic acid was used to detect hepatitis A virus (HAV) and rotavirus (SA11) in shellfish (oysters and hard-shell clams) by hybridization tests. Infectious virus, seeded into relatively large quantities of shellfish, was recovered consistently, with greater than 90% efficiency as measured by either in situ hybridization (HAV) or plaque assay (rotavirus SA11). Viral nucleic acid for dot blot hybridization assays was extracted and purified from virus-containing polyethylene glycol concentrates. Separation of shellfish polysaccharides from nucleic acid was necessary before viral RNA could be detected by dot blot hybridization. Removal of shellfish polysaccharides was accomplished by using the cationic detergent cetyltrimethylammonium bromide (CTAB). Use of CTAB reduced background interference with hybridization signals, which resulted in increased hybridization test sensitivity. After polysaccharide removal, dot blot hybridization assays could detect approximately 10(6) physical particles (corresponding to approximately 10(3) infectious particles) of HAV and 10(4) PFU of SA11 rotavirus present in 20-g samples of oyster and clam meats. These studies show continuing promise for the development of uniform methods to directly detect human viral pathogens in different types of shellfish. However, practical applications of such methods to detect noncultivatable human viral pathogens of public health interest will require additional improvements in test sensitivity.

[Study on T-lymphocyte culture and function of T-lymphocyte subsets in patients with aplastic anemia]

T-lymphocytes form the peripheral blood of 12 patients with aplastic anemia (AA) and 4 patients with aplastic anaemia-paroxysmal hemoglobinuria syndrome (AA-PNH) were cultivated and their subsets were measured by monoclonal antibodies CD4, CD8, CD25 with indirect immunofluorescence technique. Change of the proportion of T-lymphocyte subsets was observed in 5 patients with AA after the mononuclear cells were activated with phytohemagglutinin (PHA). Its was shown that the number of CFU-T of the patients with AA was apparently decreased in comparison with that of normal controls (P less than 0.05). Disorder of T-lymphocyte subsets took place in patients with AA. The percentages of CD8 and CD25 lymphocytes were increased. The helper: suppressor T-lymphocytes (CD4:CD8) ratio was significantly increased (P less than 0.01). In the cases of AA-PNH, the number of CFU-T was significantly increased (P less than 0.01) and that of T-lymphocyte subsets did not change. The ratio of CD4/CD8 in 5 patients with AA was further decreased after activating mononuclear cells with PHA. These results showed that the increase of T-lymphocytes in patients with AA may account for the low level of CFU-T; the high level of CFU-T in patients with AA-PNH may be related to the multiplication of bone marrow cells. However, there may be a potential disorder of immune system on patients with AA at the same time.

The effect of carbamylcholine on CFU-s differentiation

The proportion of spleen colony-forming units (CFU-s) killed by hydroxyurea was greatly increased after bone marrow cells (BMCs) from LACA mice were exposed to carbamylcholine (Cach; 1 X 10(-13) to 1 X 10(-9) in vitro and there was a marked change in the proportion of spleen colony types. Following treatment with Cach, granulocytic and mixed erythroid-type colonies increased from 20 to 26.3% and 16.1 to 29.6% in 9-day colonies and from 8.3 to 28.2% and 21.7 to 39.4% in 13-day colonies, respectively. Single cell suspensions of spleen colonies were made for granulocyte-macrophage progenitor (CFU-gm) and late erythroid progenitor (CFU-e) assays. The number of CFU-gm from Cach-treated BMC was about twice that from control BMC for both day 9 and day 13 groups; the number of CFU-e decreased relatively. The results suggest that cholinergic receptors on CFU-s may increase the tendency to differentiate into the granulocytic/monocytic line.

[Effects of histamine H2-receptor antagonists on hemopoietic reconstruction in bone marrow]

The effects of histamine H2-receptor antagonists (cimetidine and ranitidine) on bone marrow hematopoiesis of normal and sublethally irradiated mice were investigated. It was found that non-toxic dosage of cimetidine had no significant effect on CFU-s of the normal mouse, but it inhibited CFU-GM growth with a dosage-dependent relationship and the recovery of CFU-s formation from sublethal gamma-ray irradiation. These results suggest that histamine may play a role in bone marrow regeneration after sublethal irradiation. Histamine H2-receptor antagonists can inhibit hemopoietic reconstruction in regenerating bone marrow.

[Effects of carbamylcholine and impromidine on cell cycle state of CFU-S]

In normal steady-state conditions, there was less than 10% loss of CFU-S due to hydroxyurea (HU, 10(-3) mol/L). The CFU-S killed by HU was greatly increased after bone marrow cells of LACA mice were exposed in vitro to carbamylcholine (Cach) (10(-13)-10(-9) mol/L) and impromidine (Impro) (10(-9)-10(-4) mol/L). They were 32.8 (Cach) and 38.4% (Impro) for day 9 CFU-S; 60.6 (Cach) and 49.5% (Impro) for day 13 CFU-S at plateau phase. The effects were blocked by antagonists of cholinergic N receptor d-tubocurarine and of histamine H2 receptor cimetidine, respectively. The different sensitivity to agonists between CFU-S forming early spleen colonies and late colonies may reflect differences in receptor density on the surface of haemopoietic stem cells or receptor activity. The studies provide additional evidence suggesting the heterogeneity of pluripotent haemopoietic stem cells.

Prediction of aphakic refractive error in children

Formulas created to predict the optical requirements of the aphakic eye have been tested mainly in adult eyes. The accuracy of these formulas in shorter pediatric aphakic eyes was examined using retrospective analysis of 17 aphakic pediatric patients. The Sanders-Retzlaff-Kraff contact lens formula, used previously to predict required lens powers for epikeratophakia, consistently underestimated the required aphakic correction in the shorter eyes, which may have been responsible in part for the large undercorrections obtained previously in patients under one year of age. The Hoffer-Colenbrander and Binkhorst theoretical formulas, Donzis-Kastl-Gordon percentage change formula, and a linear regression formula derived from the present data (LIN), were significantly more accurate. The differences between these formulas were not significant. The use of one of these formulas should facilitate prediction of required epikeratophakia lenticule power or intraocular lens power in young children.