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Biomedical subjects

A Lee

Publications and source records attributed to A Lee.

At least 559 records · Page 31Linked to original sources
PubMed1993

A weak B antigen with serologic reactivity between B1 and B2 red blood cells found in a Chinese family.

During a serologic study on red cell samples from individuals representing three generations of a Chinese family, an unusual pattern of reactivity was noted in a sample from a daughter of an A1B2 individual. The results of direct ABO grouping, titration, and adsorption studies demonstrated that the red blood cells (RBCs) from the proposita and two of the proposita's uncles (1) expressed more B antigen than group B2 RBCs but less than group B1 RBCs; (2) expressed the B1 antigen but at a lower level than group B1 RBCs; and (3) expressed more H antigen than B1 RBCs but slightly less than B2 RBCs. The saliva from the proposita contained soluble B and H antigens, and her serum contained a weak B-gene-specified transferase. Serologic reactivity of her RBCs was intermediate between that of B1 and B2, RBCs. That is similar to reactivity of Aint RBCs, which is intermediate between A, and A2 RBCs. The proposita may represent a Bint phenotype.

Journal Article↗
PubMed1993

Inhibition of apoptosis and prolongation of neutrophil functional longevity by inflammatory mediators.

Neutrophil apoptosis leads to macrophage ingestion of intact senescent neutrophils. This may represent a neutrophil removal mechanism that is important both in the control of inflammatory tissue injury and for the normal resolution processes of inflammation. Because apoptosis is likely to be a key control process in cell and tissue homeostasis, a number of inflammatory mediators were tested for their ability to modulate the rate of apoptosis in populations of neutrophils aging in culture. Endotoxic lipopolysaccharide, human recombinant complement factor 5a, and human recombinant granulocyte-macrophage colony-stimulating factor all markedly inhibited the rate of neutrophil apoptosis in a concentration-dependent fashion, without inducing necrosis (as assessed by trypan blue exclusion). This inhibitory effect on the rate of neutrophil apoptosis was shown by morphological criteria and confirmed by gel electrophoresis of extracted DNA. Inhibition of apoptosis of aging neutrophil populations was associated with prolongation of the functional life span of the population as assessed by the ability of neutrophils to spread on glass surfaces, to polarize in response to deliberate stimulation with N-formyl-Met-Leu-Phe (fMLP), and to release the granule enzyme marker myeloperoxidase on fMLP stimulation. These observations show that inflammatory mediators prolong the functional life span of neutrophils through modulation of apoptosis. Further elucidation of these mechanisms will lead to a better understanding of the processes controlling neutrophil residence and function in inflamed tissues and may provide further insights into the molecular mechanisms of apoptosis, which is of widespread importance in tissue biology.

Apoptosis↗
PubMed1993

Gastric bacteria other than Helicobacter pylori.

Since the culture of Helicobacter pylori from the human stomach in 1983 there has been renewed interest in other bacteria that had been observed in animal stomachs as early as late in the nineteenth century. Many of these bacteria have now been isolated and have been shown to belong to the same genus, Helicobacter, which currently contains nine species. Study of the gastric helicobacters is important because it provides relevant information about how bacteria can survive in the gastric environment and induce disease. Bacteria of special importance include "Gastrospirillum hominis," a distinctive tightly spiralled bacterium commonly found in cats and dogs, recently shown to be a helicobacter, and that infects a small proportion of human patients, causing a mild chronic gastritis; Helicobacter felis, a bacterium isolated from cats that has been found to be associated with gastritis in one human patient but easily colonizes small laboratory animals, causing gastritis and thus providing a useful model of the human infection; and Helicobacter mustelae, the natural inhabitant of the ferret gastric mucosa, where it also induces a form of chronic gastritis. The latter bacterium shares important properties with H. pylori, namely an ability to adhere firmly to gastric mucosae and an association with peptic ulceration. Investigation of these non-H. pylori gastric bacteria in natural or experimental hosts provides useful models of H. pylori-associated gastroduodenal disease, makes possible assessment of potential therapeutic regimens, and provides information that may result in the development of novel intervention strategies.

Animals↗
PubMed1992

Concentration-dependent modulation of basic fibroblast growth factor action on multiplication and locomotion of human teratocarcinoma cells.

A human teratoma cell line (Tera 2) was grown in serum-free medium, and the population multiplication was stimulated by the addition of 1-10 ng basic fibroblast growth factor (bFGF)/ml. The bFGF-effect was abrogated by the addition of protamine sulphate. When high concentrations of bFGF were added, a preferential effect on cell locomotion was observed. 100 ng bFGF/ml stimulated cell movement but only exerted a marginal effect on cell multiplication. These observed exogenous requirements for multiplication and locomotion were complemented by the expression of bFGF receptors. Scatchard analysis of binding data suggests the existence of a high-affinity and a low-affinity class of receptors.

Cell Division↗
PubMed1992

Use of recombinant fusion proteins for generation and rapid characterization of monoclonal antibodies. Application to the Kunitz domain of human beta amyloid precursor protein.

Production of peptides by recombinant DNA techniques is an efficient alternative to chemical synthesis of peptides. Proteins and peptides produced by recombinant DNA methods in E. coli are routinely used as antigens for the production of antibodies. However, most small peptides are rapidly degraded within the E. coli cell, and therefore, must initially be expressed as components of larger, more stable fusion proteins. The peptide of interest must be cleaved from the fusion protein, and purified prior to immunization to eliminate epitopes contributed by the fusion partner. We have now established methods for the production and characterization of monoclonal antibodies using partially purified, uncleaved fusion proteins. We have also described a method for efficient production and detection of the fusion protein, an EIA for rapid differential screening of hybridoma supernatants, and a strategy for epitope mapping of the antibodies. These methods have been applied to the production and characterization of monoclonal antibodies specific for a 75-amino-acid internal segment of the Alzheimer amyloid precursor protein, and should be applicable to a wide variety of other peptides and proteins.

Amyloid beta-Protein Precursor↗
PubMed1992

Relation of fetal and infant growth to plasma fibrinogen and factor VII concentrations in adult life.

OBJECTIVE: To determine whether reduced fetal and infant growth are associated with higher plasma fibrinogen and factor VII concentrations in adult life. DESIGN: Follow up study of men born during 1920-30 whose weights at birth and at 1 year had been recorded by health visitors, and men born during 1935-43 whose size at birth had been measured in detail. SETTING: Hertfordshire and Preston, England. SUBJECTS: 591 men born in east Hertfordshire who still lived there and 148 men born in Preston who still lived in or close to the city. MAIN OUTCOME MEASURES: Plasma fibrinogen and factor VII concentrations. RESULTS: Among men in Hertfordshire mean plasma fibrinogen and factor VII concentrations fell with increasing weight at 1 year (from 3.21 g/l in men of less than or equal to 18 lb to 2.93 g/l in men greater than or equal to 27 lb and from 122% of standard to 103%; p less than 0.001, p less than 0.005 respectively). The trends were independent of cigarette smoking, alcohol consumption, body mass index, and social class. Neither plasma fibrinogen nor factor VII concentration was related to birth weight. In men in Preston, however, fibrinogen concentration fell progressively as the ratio of placental weight to birth weight decreased (p = 0.01). CONCLUSIONS: Reduced growth in fetal life and infancy is strongly related to high plasma concentrations of the haemostatic factors fibrinogen and factor VII. This may be a persisting response to impaired liver development during a critical early period.

Aged↗
PubMed1992

Race, integration and family planning in Trinidad and Tobago.

"The study considered the effect of the integration of the health services on family planning in Trinidad and Tobago. A drop-out study was based on a sample of six clinics, three representing integrated and three clinics that were non-integrated or vertical. Efforts were also made to solicit the views of a sample of drop outs, current acceptors and health-care providers. The study found that there were characteristics of the population from which acceptors were drawn that were more important in explaining utilization than the question of integration or non-integration of the clinics. Many of the problems were organizational and could, with adequate financing, be met by an even higher level of integration."

Americas↗
PubMed1992

Intrapartum amniotic fluid index and its relationship to fetal distress.

Amniotic fluid index was measured in 50 consecutive laboring women after membrane rupture. The 10th percentile of the normal range was 6.2 cm. Thirty-three women had a repeat measurement by a second observer. Although there was no systematic bias between the two observers, the limits of agreement were wide: 95% of the measurements by one observer were between 0.59 and 2.07 times those of the second. Closer agreement was observed when amniotic fluid index was low (less than 6.2 cm). The relationship between intrapartum amniotic fluid index and fetal distress was then investigated in a further 60 laboring women. When compared with women with a normal intrapartum amniotic fluid index, women with a low amniotic fluid index had higher incidences of fetal heart rate abnormalities during the first stage of labor (64% vs 20%, p less than 0.01), meconium (grade II or III) at delivery (64% vs 35%, p less than 0.05), and operative delivery for fetal distress (57% vs 17%, p less than 0.01). Umbilical artery pH and Apgar scores were, however, similar for the two groups. Measurement of intrapartum amniotic fluid index may be an appropriate method for selecting women suitable for intrapartum aminoinfusion.

Amniotic Fluid↗
PubMed1992

A cytotonic, cholera toxin-like protein produced by Campylobacter jejuni.

1. Campylobacter jejuni is a major cause of gastroenteric infection. 2. This organism appears to produce both cytotonic and cytotoxic virulence factors. 3. We report here that culture filtrates of some clinical isolates of C. jejuni induce elongation of Chinese hamster ovary (CHO) cells in vitro but do not cause inhibition of fluid absorption in the rat ileum. 4. These culture filtrates contain low levels of a protein which cross-reacts immunologically with the cholera toxin. 5. The cholera toxin-like protein of C. jejuni behaved identically to cholera toxin on non-denaturing polyacrylamide gel electrophoresis. 6. Under denaturing conditions, however, this protein displayed no subunit structure and a molecular weight of approximately 50 kDa with many higher molecular weight aggregates. 7. In conclusion, isolates of C. jejuni produced small amounts of enterotoxin when grown in vitro. 8. The toxin cross-reacted immunologically with cholera toxin and has a similar native structure, but does not appear to possess subunits.

Animals↗
PubMed1992

The role of teacher knowledge in elementary physical education instruction: an exploratory study.

The purpose of this study was to describe how providing teachers with research based knowledge about developmental throwing can influence teachers' observational interpretations and their students' practice patterns. Eight kindergarten classroom teachers with high generic teaching skill competence taught a 6-week overhand throwing unit to the children in their intact classes. Prior to the unit, four of the teachers were randomly assigned to a 4-hour knowledge training program. The other four teachers served as a comparison group (underwent no knowledge training). During the unit, data from stimulated recall interviews were used to describe and compare the thoughts and knowledge concepts expressed by the two groups of teachers. The throwing practice experienced by the children in the knowledge-trained and comparison teachers' classes was videotaped and analyzed for frequency of opposite foot stepping. The knowledge acquired during training was associated with different patterns of skill observation. The knowledge concepts the teachers acquired during training formed the basis of many of their thoughts and were reflected in the instructional procedures implemented. The knowledge-trained teachers' classes demonstrated more than twice as many opposite foot throws during the unit than the comparison teachers' classes.

Achievement↗
PubMed1992

Epidemiology of Helicobacter pylori in southern China: identification of early childhood as the critical period for acquisition.

A large cross-sectional study to investigate the prevalence and possible modes of transmission of Helicobacter pylori was done in southern China. Serum samples (1727) were collected from Guangzhou city and three rural areas of Guangdong Province, and the prevalence of H. pylori infection was determined using an ELISA. Each subject completed a questionnaire. The overall prevalence of H. pylori infection was 44.2%; a significantly higher prevalence was found in Guangzhou (52.4%) than in the rural areas (38.6%). This difference was generally reflected in the group 0-5 years old, but the rate of increase in seroprevalence for H. pylori over 5 years of age was similar (1%/year). This study provides important new data on the acquisition of H. pylori, particularly in the early years of life, and shows that density of living conditions is a prime determinant in the acquisition of H. pylori.

Adolescent↗