Effects of hemolysis, hematocrit, RBC swelling, and flow rate on light scattering by blood in a 0.26 cm ID transparent tube

The intensity of light scattering by blood in a tube of diameter 0.26 cm was measured with an apparatus devised by us at different angles on an incident cross-sectional plane. Changes in angular distribution of light intensity associated with hemolysis, and changes in hematocrit (Ht), red blood cell (RBC) swelling, and flow rate were plotted on polar coordinates. The dyssymmetry index, defined as the ratio of the intensity of light at 45 degrees to that at 135 degrees, was used to characterize the shape of the diagrams of light scattering. The index decreased with Ht, flow rate, but increased with RBC swelling. It is concluded that light scattering by blood requires intactness of the RBC membrane. Even when the cell membrane is intact, light scattering is subject to changes with the flow rate of blood, presumably due to RBC aggregation.     

Amplifiedbcl-2/JH rearrangements in reactive lymphadenopathy

Using the polymerase chain reaction (PCR) to examine the occurrence ofbcl-2/JH joining produced by t(14;18) chromosomal translocation, amplified DNA was detected in 2 of 18 lymph nodes showing reactive lymphadenopathy. The PCR was repeated in these two lymphs nodes using the same DNA samples, but no amplification was detected at the second attempt. Thus the amplified DNA was considered to be derived from one copy of joinedbcl-2/JH in one cell, or from a few copies in a few clonal cells with the same joinedbcl-2/JH. These results suggest that false joining ofbcl-2/JH at the t(14;l8) junction may occur in reactive lymph nodes.     

Human erythroid cells produced ex vivo at large scale differentiate into red blood cells in vivo

New sources of red blood cells (RBCs) would improve the transfusion capacity of blood centers. Our objective was to generate cells for transfusion by inducing a massive proliferation of hematopoietic stem and progenitor cells, followed by terminal erythroid differentiation. We describe here a procedure for amplifying hematopoietic stem cells (HSCs) from human cord blood (CB) by the sequential application of specific combinations of growth factors in a serum-free culture medium. The procedure allowed the ex vivo expansion of CD34+ progenitor and stem cells into a pure erythroid precursor population. When injected into nonobese diabetic, severe combined immunodeficient (NOD/SCID) mice, the erythroid cells were capable of proliferation and terminal differentiation into mature enucleated RBCs. The approach may eventually be useful in clinical transfusion applications.     

Life cycles of two limnetic cyclopoid copepods, Cyclops vicinus and Thermocyclops crassus, in two different habitats

The life cycles of Cyclops vicinus and Thermocyclops crassusin two shallow eutrophic habitats, Junsainuma and Naganuma Ponds,Hokkaido, Japan, were investigated. Both ponds exhibited similarseasonal patterns of temperature, oxygen levels and pH duringice-free periods; however, oxygen levels were extremely lowerunder the ice in Naganuma Pond. Cyclops vicinus showed differentlife cycles in the two ponds; in Junsainuma Pond, it reproducedin winter and spring (January-May) and entered diapause duringsummer and autumn (June-October) as copepodite IV stage, whileit reproduced in autumn (October-November) and spring (April-May),and entered diapause in summer (June-September) and winter (Januaryand February) as copepodite V stage in Naganuma Pond. Thermocyclopscrassus entered diapause during winter (December-April) as copepoditeIV and V stages in both ponds, and egg-bearing females appearedonly during the warmseason, from early May to late October,when water temperatures were >10°C. Summer diapause inC.vicinus was suggested to be an adaptation against fish predation,whereas C.vicinus entered winter diapause in Naganuma Pond probablyto avoid low oxygen levels. Thermocyclops crassus entered diapausein both ponds to avoid low water temperature. These resultssuggest that biotic and abiotic factors are important for leadingto specific life cycles of cyclopoid copepods in small waterbodies.     

Interannual variations in abundance and body size in Neocalanus copepods in the central North Pacific

As the integral components of zooplankton in the subarctic NorthPacific, the three Neocalanus species (N. cristatus, N. plumchrusand N. flemingeri) are characterized by an annual life cycleand rapid development in the surface layer during spring–summer.Patterns of interannual variation of abundance and body sizeof these Neocalanus species were analyzed using the time-seriesdata collected during the summers of 1979–1998 (20 years)at stations along the longitudinal transect line in the centralNorth Pacific, crossing five sub-areas (Alaska Current System,Subarctic Current System, Northern Transition Domain, SouthernTransition Domain and Subtropical Current System). In the southernsub-areas, quasi-decadal oscillation was observed for the 3-yearrunning mean of abundance and prosome length for copepoditestage 5 (C5) of the three Neocalanus species. Although the oscillationsignal diminished towards northern waters, it showed a positivephase during the early 1980s and 1990s and a negative phaseduring the late 1980s. In the northern waters, a biennial patternwas pronounced for anomalies of C5 prosome length for N. plumchrusand N. flemingeri, which was large in odd years and small ineven years. Significantly positive covariations among the threespecies were found for both abundance and prosome length aroundmid-latitude, where they were abundant. In the correlation analysis,these observed yearly patterns showed a statistically insignificantcorrelation with most environmental (integrated mean temperaturein surface waters, water column stability and chlorophyll aconcentration) or climatological (North Pacific Index and SouthernOscillation Index) variables. The regional difference of theoscillation signal and the synchronized covariation among thesespecies suggest that interannual variations of their abundanceand body size are mediated by common environmental force(s)with some spatial and temporal scales in the subarctic NorthPacific.     

Ex vivo generation of fully mature human red blood cells from hematopoietic stem cells

We describe here the large-scale ex vivo production of mature human red blood cells (RBCs) from hematopoietic stem cells of diverse origins. By mimicking the marrow microenvironment through the application of cytokines and coculture on stromal cells, we coupled substantial amplification of CD34(+) stem cells (up to 1.95 x 10(6)-fold) with 100% terminal differentiation into fully mature, functional RBCs. These cells survived in nonobese diabetic/severe combined immunodeficient mice, as do native RBCs. Our system for producing 'cultured RBCs' lends itself to a fundamental analysis of erythropoiesis and provides a simple in vitro model for studying important human viral or parasitic infections that target erythroid cells. Further development of large-scale production of cultured RBCs will have implications for gene therapy, blood transfusion and tropical medicine.     

Ontogenetic Vertical Migration and Life cycle of Neocalanus Plumchrus (Crustacea: Copepoda) in the Oyashio Region, with Notes on Regional Variations in Body Sizes

The ontogenetic vertical migration and life cycle of Neocalanusplumchrus were investigated by anal-yzing monthly populationstructure at Site H in the Oyashio region from September 1996through October 1997. Additional sampling was also done at severalstations covering the entire subarctic Pacific, Okhotsk Seaand Japan Sea as a basis for regional comparison of life cyclesand body sizes. At Site H, N. plumchrus spawned October to Aprilbelow 250 m depth. Young copepodite stages (C1–C5) occurredduring June late in the phytoplankton bloom. The C5 migratedto the deeper layers in July–August where they moltedto adults. Development time of C5 to C6 was highly variable.The ontogenetic vertical migration of N. plumchrus ranged fromthe surface to 1000–2000 m depth, and the life cycle wasannual. Temporal data on population structure and vertical distributionsuggestedthe annual life cycle was generally synchronized throughoutthe subarctic Pacific and its marginal seas. Geographical comparisonof C5 prosome length indicated the occurrence of significantlylarge specimens in the Oyashio region and Okhotsk Sea but smallspecimens in the Japan Sea. Possible causes for regional variabilityin body sizes are discussed.     

Characterization and repartition of epidermal growth factor-urogastrone receptors in gastric glands isolated from young and adult guinea pigs

Physiological studies indicate that epidermal growth factor-urogastrone (EGF) acts on stomach epithelium as mitogen and modulator of acid secretion. Here, we studied the binding of 125I-EGF to gastric glands isolated from the guinea-pig fundus (acid-secreting part) and antrum. At 20 degrees C, the association of 125I-EGF to gastric glands was time-dependent (plateau at 90 min) and reversible (75-85% dissociation in 1 h). No degradation of the peptide was detected, but a time-dependent loss of binding capacity was observed. At apparent equilibrium (90 min, 20 degrees C) unlabelled EGF (80 pM to 80 nM) competed with 125I-EGF-binding in the same manner in antrum and fundus (50% inhibition, with 0.6 nM EGF). Whereas kinetics properties were similar in antrum and fundus, the binding capacity was 40-55% lower in fundus than in antrum in young animals (6-8 weeks). By contrast, in adult animals (20-30 weeks), binding was the same in both parts of stomach. Scatchard analysis showed that two orders of binding sites were present in all cases (Ki 0.34-0.47 nM, Ki 2.2-3.4 nM), and that the differences observed were only accounted for by number of binding sites. These results show that EGF possess high affinity binding sites on gastric epithelium. These sites, dependent upon the age of the animals, may be related to the modulations by EGF of gastric trophism and secretions.