Search PubMed⌕ Search

Biomedical subjects

H Lee

Publications and source records attributed to H Lee.

At least 901 records · Page 50Linked to original sources
PubMed1979

Comparison of Xe-133 washout and single-breath imaging for the detection of ventilation abnormalities.

The Xe-133 ventilation studies of 115 patients were analyzed to determine the relative abilities of the single-breath and washout phases to detect regional ventilation abnormalities. All Xe-133 images were obtained in the posterior projection before 6-view perfusion studies with Tc-99m human albumin microspheres. There were 275 regions with matching V-P abnormalities in the patients. The washout portion of the study detected 258 of these regions (94%) and the single breath detected 175 (64%) (p less than 0.01). The discrepancies were confined to regions with nonsegmental perfusion defects, where the single breath detected 139 matches and the washout 216. The discrimination ratio between normal areas and areas of obstructive lung disease improved from 2 to 1 after 1 min washout to 30 to 1 after 5 min. The late phases of Xe-133 washout are useful in detecting ventilation abnormalities, especially those associated with nonsegmental perfusion defects.

Adolescent↗
PubMed1978

Influenza immunization in immunosuppressed children.

Optimal influenza immunization of individuals with malignancy and other immunodeficient states requires and understanding of responses to currently recommended regimens. Children with acute lymphocytic leukemia and other malignancies between three and 17 years of age were immunized with bivalent influenza vaccine containing A/New Jersey/76 and A/Victoria/75. Folowing a two-dose immunization schedule, only 37% (25468) on cancer chemotherapy seroconverted to a hemagglutination inhibition titer greater than or equal to 20 for A/NJ/76; the seroconversion rate in those not on chemotherapy was 92% (68/74, P less than 0.001). The immune response to the A/Vic/75 antigen was also related to a history of recent chemotherapy. There was no correlation between the immune response and the peripheral white blood cell count except at counts less than or equal to 1,000. The optimum time to immunize children with malignancies is when they have been off chemotherapy for one month and have peripheral white blood counts greater than 1,000.

Adolescent↗
PubMed1978

Studies on dispersed unincubated chick blastoderm cells. I. Early phases of aggregation.

Early phases of aggregation of dispersed unincubated chick blastoderm cells were investigated. Dispersed cells, when maintained in appropriate cultures, began adhering to one another almost immediately and eventually formed spherical aggregates without any recognizable structures except for occasional blood islands, after 24 hr of incubation. The number and size of aggregates derived from dispersed cells depended largely upon the speed of rotation and initial cell density. Treatment with colchicine (4 microgram/ml) had no apparent effect on adhesion of cells, although it yielded smaller aggregates than controls, especially after 14 hr of incubation. Direct observation on mitotic activity, estimations of cell number and nucleic acid content, and pulse labeling experiments with 3H thymidine clearly showed that aggregates were derived entirely from adhesion of free cells and/or fusion of smaller aggregates during the first 12 to 13 hr of incubation. In addition, all cell types present in the unincubated blastoderm contributed to the formation of aggregates, not one particular cell type.

Animals↗
PubMed1978

Studies on dispersed unincubated chick blastoderm cells. II. Formation of contacts and cell sorting in aggregates of unincubated chick blastoderm and heart cells.

The configuration of blastoderm-heart cell aggregates after cell sorting depended largely on the proportion of each cell type initially present in the culture. In heterotypic aggregates, blastoderm cells were always found to partially or completely surround heart cells with both cell types retaining their characteristic morphology. Specialized junctions (e.g. desmosomes) developed only between cells of the same type. These observations suggest that blastoderm cells are unable to recognize and form stable contacts with heart cells.

Animals↗
PubMed1978

Down's syndrome and leukemia: mechanism of additional chromosomal abnormalities.

There is an increased incidence of acute leukemia in patients with Down's syndrome patients have a trisomy-21 chromosomal pattern, and chromosomal abnormalities can be seen in acute leukemia. It is possible that the increased incidence of acute leukemia in Down's syndrome persons may be due in part to their chromosomal abnormalities. Such abnormalities, some appearing in a stepwise clonal evolution, were found in five Down's syndrome patients, four with acute leukemia and one with abnormal regulation of leukopoiesis. Morphological abnormal chromosomes were also found in three patients. These chromosomal abnormalities are similar to those seen in non-Down's syndrome leukemic patients. There is suggestive evidence for clonal evolution hypothesis of luekemogenesis in non-Down's syndrome patients. The abnormal chromosomal pattern reported in our Down's syndrome patients could be the result of nondisjunction in mitosis, and leukemia may be the phenotypical expression of this nondisjunction.

Acute Disease↗
PubMed1978

The role of the cell surface in the migration of primordial germ cells in early chick embryos: effects of concanavalin A.

Effects of concanavalin A (Con A) on the morphology and migration of primordial germ cells (PGCs) in stage-6 to -12 chick embryos were investigated. Con A, at a sublethal dose (10 microgram/ml), inhibited migration of PGCs from the germinal crescent area to other parts of the embryo. Affected PGCs were more rounded without the usual cytoplasmic extensions, but the integrity of other structures was unaffected. Nearly identical results were obtained with another lectin, wheat germ agglutinin (10 microgram/ml). Histochemistry using Con A-horseradish peroxidase revealed that PGCs in control embryos had a thin, rather uniform layer of extracellular coat material (ECM). Con A appeared to alter the distribution of ECM on PGCs, i.e. some parts of the cell surface were devoid of any detectable ECM, while others had small, scattered patches of ECM. Con A effects were alleviated by alpha-methyl-D-mannoside. Overall results of the present study indicated that the observed inhibition of PGC migration in early chick embryos is a consequence of Con A-induced alterations of cell surface properties.

Animals↗
PubMed1977

Trial of bivalent influenza A vaccine in high-risk infants.

A vaccine trial involving 50 high-risk infants, aged six to 36 months, was performed for evaluation of the safety of a split-virus bivalent influenza A vaccine. After immunization, 18% of the infants developed a fever of greater than or equal to 100 F and 7% had fever of greater than or equal to 102 F. Other reactions to the vaccine were few. However, the reaction index of these high-risk infants to the bivalent vaccine was higher than those of older children receiving the same vaccine and normal infants receiving the monovalent vaccine. Forty-one percent of the infants responded with a titer of hemagglutination-inhibiting antibody of greater than or equal to 1:20 to the A/Victoria/75 component of the bivalent vaccine, and 35% responded to the A/New Jersey/8/76 component. This result suggested that this vaccine used in two doses would be an effective vaccine for infants. The infants generally tolerated the vaccine well. Nevertheless, the rapid development of fever would be of concern in the infant whose underlying disease was marginally compensated.

Antibodies, Viral↗
PubMed1977

Structural and functional aspects of biological freezing techniques.

The cooling procedures used to prepare samples for ultrastructural examination at low temperatures often differ markedly from those used to recover optimal function of cells on thawing. The implications of these differences are reviewed. Damage and alteration to the structure and function of the cells may be caused by the high concentrations of cryoprotective agents such as glycerol or dimethyl sulphoxide (DMSO) often added to reduce ice crystal artefacts. Under the rapid cooling conditions commonly employed for structural studies, these additives are not cryoprotective; low rates of cooling are necessary for them to be effective. Rapidly cooled cells that contain intracellular ice are only injured during rewarming so their structure may be as yet unaltered by any damaging effects at low temperatures. Most cells able to recover on thawing are grossly shrunken at low temperatures but since they are potentially functional they are of interest structurally. These cryobiological principles are illustrated with freeze-fracture, freeze substitution and functional assays. The cell types chosen were Chlorella sp. and mammalian tissue culture cells.

Animals↗