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Biomedical subjects

L Mason

Publications and source records attributed to L Mason.

At least 37 records · Page 2Linked to original sources
PubMed1995

NK cell subsets in the regulation of murine hematopoiesis. I. 5E6+ NK cells promote hematopoietic growth in H-2d strain mice.

NK cells are able to reject bone marrow allografts in lethally irradiated mice. 5E6 is a marker expressed on a subset of NK cells that is responsible for the rejection of H-2d homozygous bone marrow cell (BMC) allografts. This suggests that the 5E6+ NK cell subset somehow recognizes and is deleterious for H-2d BMC. However, unlike Ly-49+ NK cells, 5E6+ cells are not deleted or even down-regulated in H-2d-homozygous mice. We wanted to determine, therefore, the role of the 5E6+ and 5E6- NK cell subsets in the normal physiologic regulation of hematopoiesis in H-2d strains of mice. Surprisingly, both in vivo depletion studies of normal mice and studies in which the subsets were purified and cultured with syngeneic BMC in vitro demonstrated that in H-2d mice, the 5E6+ subset of NK cells did not inhibit, but instead promoted, growth of H-2d BMC. Depletion of the 5E6+ subset also resulted in decreased marrow engraftment after syngeneic bone marrow transplantation in H-2d mice. Analysis of the cell culture supernatants of the purified subsets indicated that the functional effects of the subsets on hematopoiesis correlated with the relative amounts of hematopoietic growth-promoting cytokines produced by the NK cells. These results demonstrate that physiologically relevant subsets of NK cells exist that are involved in the homeostatic regulation of hematopoiesis and that they can be distinguished on the basis of 5E6 expression.

Animals↗
PubMed1994

What about the health of ancillary staff? A management audit.

Health at Work in the NHS was launched at the same time as Health of the Nations, in July 1992. There is good national and local evidence identifying ancillary staff as a priority for health promotion. Despite the evidence, and a regional drive to make work with ancillary staff a priority, a recent audit made clear that very little has happened. Market testing seems to have excluded ancillary staff health from senior management responsibility. discusses possible reasons and the implications.

Allied Health Personnel↗
PubMed1992

Breast cancer incidence in women with abnormal cytology in nipple aspirates of breast fluid.

This is a prospective study of breast cancer risk in relation to nipple aspirate fluid cytology in 2,701 volunteer white women from the San Francisco Bay Area first enrolled between 1973 and 1980. The women were not pregnant or lactating and were free of breast cancer within 6 months of entry into the study. The breast cancer status of this cohort was determined between June 1988 and April 1991. Follow-up was complete for 87% (n = 2,343) of the cohort, representing 29,961 person-years and an average of 12.7 years of follow-up. The overall breast cancer incidence was 4.4% (104 of 2,343) and rose with fluid cytology findings as follows: no fluid obtained, 2.6% (9 of 352); unsatisfactory specimen, 4.8% (15 of 315); normal cytology, 4.3% (56 of 1,291); epithelial hyperplasia, 5.5% (18 of 327); and atypical hyperplasia, 10.3% (6 of 58). Relative risks for breast cancer and their 95% confidence intervals were estimated by Cox regression, adjusting for age and year of entry. Compared with the relative risk for women who yielded no fluid, relative risks were: unsatisfactory specimen, relative risk (RR) = 1.4 (95% confidence interval (CI) 0.6-3.3); normal cytology, RR = 1.8 (95% CI 0.9-3.6); epithelial hyperplasia, RR = 2.5 (95% CI 1.1-5.5); and atypical hyperplasia, RR = 4.9 (95% CI 1.7-13.9). These findings were strongest for and were mainly confined to women aged 25-54 years. Women with atypical hyperplasia and a first-degree family history of breast cancer were six times more likely to develop breast cancer than were women with atypical hyperplasia but without a family history of breast cancer (95% CI 1.0-30.2). These findings provide strong support for our hypothesis that hyperplasia and atypical hyperplasia diagnosed in nipple aspirates of breast fluid are associated with an increased risk of breast cancer.

Adolescent↗
PubMed1992

Histological assessment of the mouse uterus from birth to puberty for the appearance of LGL-1+ natural killer cells.

The appearance of natural killer (NK) cells during growth and maturation of the murine uterus was studied by immunohistochemistry, using the monoclonal antibody LGL-1. To determine the contributions of microorganisms in the environment and of T-cell and B-cell regulation to the establishment of a uterine NK cell population, uteri from barrier-raised, flora-defined, random-bred CD-1 mice and from genetically T-cell- and B-cell-deficient SCID mice (genotype C.B-17 scid/scid) were compared to uteri from conventionally raised CD-1 mice. Uteri were studied from birth to the ages at which these mice are normally paired for mating (7-10 wk). Absolute uterine weight and the ratio of uterine weight to body weight increased remarkably between 3 and 5 wk of age in each group of animals. Growth continued beyond Week 5 of age, and in all groups the ratio of uterine weight to body weight was similar at puberty, although both the flora-defined CD-1 and SCID mice were significantly smaller than conventionally reared mice. LGL-1+ cells could not be detected in any of the neonatal uteri examined. LGL-1+ cells were first detected at 2 wk of age in uteri from the conventional and flora-defined CD-1 mice. A significant increase in the number of LGL-1+ NK cells occurred in the CD-1 uterus between Weeks 2 and 3 of age and again between Weeks 5 and 7 of age. Environmental conditions did not alter the frequency of LGL-1+ cells between the two groups of CD-1 mice at any age studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1990

Spontaneous phenotypic and karyotypic progression in the SV40 transfected cell line SVG during prolonged passage in vitro.

Transfection of primary cultures of human cells with origin of replication deficient SV40 DNA has been carried out by others to generate in vitro models of malignant transformation in vivo. The present work describes progressive alterations in karyotype and phenotype in one such transfected (neuroglial) cell line (SVG). After repeated passage, recognisable marker chromosomes evolved. These may be related to karyotypic anomalies found in human glial tumors. Accompanying the evolution in karyotype were changes in phenotype. Although presaging malignant transformation, these stopped short of actual tumorigenicity.

Animals↗
PubMed1989

Nipple aspirate fluids in adult nonlactating women--lactose content, cationic Na+, K+, Na+/K+ ratio, and coloration.

The presence of lactose in nipple secretions is considered biochemical evidence of breast secretory activity, and has been reported to occur more frequently in white compared to brownish or green colored breast fluid. We studied lactose, Na+, and K+ concentrations, the Na+/K+ ratio, and the coloration of nipple aspirate fluid (NAF) from 49 nonpregnant women. A significant relationship was found between the concentrations of lactose, Na+, and K+, and age and the coloration of NAF. Lactose was present in 22/49 (44.8%) of the NAF samples and declined with age from 100% positivity in women less than or equal to 29 years to 29% in those less than or equal to 35 years. In NAF of deep yellow, brown and green colorations, only traces of lactose were found. Na+ and K+ increased with age and with darker colorations compared to white, pale yellow, or colorless NAF. Lactose was present in NAF samples from both parous and nulliparous younger women, indicating that the breasts of many nonpregnant women respond to prolactin stimulation; hence, lactose may provide a simple marker indicating active physiologic secretory activity of the breast. As reported previously, NAF of darker coloration, containing elevated levels of cholesterol, cholesterol oxidation products, and other substances, suggests retention and impaired reabsorption of these and other products of secretion. Because of the secretion and temporary retention by the breast glands of chemical substances of exogenous and endogenous origin, including mutagens and carcinogens, lactose concentration and coloration of NAF may be useful as markers of secretion and reabsorption in future physiologically based clinical and epidemiologic studies of the pathogenesis of breast disease.

Adult↗
PubMed1989

Health visitors' perceptions of normal infant behaviour.

A survey of 50 health visitors revealed a wide range of views on the frequency of certain behaviour patterns associated with feeding, sleeping and crying in babies. The implications of this for health visitor training and client contact are discussed.

Child Behavior↗
PubMed1988

LGL-1: a non-polymorphic antigen expressed on a major population of mouse natural killer cells.

Rat mAb have been raised to mouse liver-derived large granular lymphocytes (LGL). One of these mAb (4D11) binds specifically to mouse LGL and appears to recognize a non-allelic determinant on NK-active cell populations. The Ag recognized by 4D11 is expressed on LGL of all mouse strains tested, including C57BL/6 (B6), BALB/c, C3H/HeJ, and SJL/J; thus, we have provisionally called this Ag LGL-1. Analysis of various lymphoid and hemopoietic tissues has indicated that only normal tissues known to contain NK activity have 4D11+ cells. With B6 and B6 congenic strains, a positive correlation exists between the number of LGL in a sample and the percentage of 4D11 immunofluorescence-positive cells detected by flow cytometric analysis. Dual color immunofluorescence analyses indicate that some LGL-1+ cells are also stained for Ly-1 and Thy-1. A very small subset exists that is weakly positive for CD3 and LGL-1. However, virtually no cells are seen which co-express LGL-1 and Ly-2. LU activity against YAC-1 targets was increased 7- to 700-fold in LGL-1+ spleen cells obtained by cell sorting from several different strains of mice (B6, BALB/c, C3H/HeJ, SJL/J, and athymic/nude). Sorted, LGL-1- spleen cells contained little or no NK activity. Cells positively selected for LGL-1 also contained between 50 and 60% LGL by morphology. By using facilitated in vitro antibody plus C' treatments, the majority of NK activity can be depleted from both B6 spleen and liver-derived leukocyte populations enriched for NK cells. mAb 4D11 was also shown to precipitate a protein of approximately 87 kDa from the surface of enriched murine NK cells. This mAb should prove valuable for understanding the role of NK cells in the immune response.

Animals↗
PubMed1988

Association of breast fluid coloration with age, ethnicity, and cigarette smoking.

Nipple aspirates of breast fluid (NAF) occur with different colorations (colorless, white, pale yellow, dark yellow, brown, green, and black). Increasing concentrations of cholesterol, cholesterol 5,6-epoxides, estrogens, and fluorescent products of lipid peroxidation have been positively associated with the dark colorations (dark yellow, brown, green, and black). Because of the absence of data on these variations in breast fluid coloration, we made an exploratory study of their possible associations with age, ethnicity, clinical breast status, and breast cancer risk factors. Dark NAF colorations increased with age among white women from 22.5% at 20-29 years to 49.2% at 50-59 years. Among Chinese and Japanese women, the overall proportion of dark breast fluids was significantly lower (highest proportion 23.5%). A positive association of dark NAF coloration was found with current cigarette smoking (odds ratio = 1.64 [1.04-2.59]). A dose response between amount smoked and dark coloration was found in women less than 50 years of age, with women who smoked more than one pack per day having an odds ratio of 2.31 (1.30-4.67). No significant association of dark NAF was found with the major breast cancer risk factors or with actual benign or malignant breast disease. The dark colorations may represent pigmented products of apocrine gland secretion, lipofuscin complexes of peroxidated lipoprotein, breakdown products of hemoglobin, and possibly, diet-related secretory products.

Adult↗
PubMed1987

Increase in liver-associated natural killer activity by polyribonucleotides.

Several polyribonucleotides are currently in clinical trials for the treatment of cancer or viral diseases. The present report in mice demonstrates that polyinosinic-polycytidylic acid and poly-L-lysine which has been stabilized in carboxymethylcellulose (poly (ICLC) as well as polyadenosinic-polyuridylic acid (poly AU), both potently augment natural killer (NK) activity in the liver, which is often a target organ for the formation of metastases during the progression of human cancer. Following the administration of poly ICLC (10 micrograms/mouse), greater NK activity as measured by lytic units (LU), was observed in the liver (445 LU) than in blood (63 LU) or spleen (20 LU). The high level of NK activity in the liver was in contrast to the low levels observed in untreated mice, and was maintained for at least 9 days post injection. NK activity in the blood and spleen returned to normal levels by day 6. Similar results were obtained with poly AU except that approximately 10-fold more poly AU (100 micrograms/mouse) was required to induce optimal augmentation of NK activity. Further studies demonstrated that the increase in liver-associated NK activity induced by poly ICLC was associated with a 10- to 20-fold increase in liver-associated leukocytes, termed nonparenchymal cells (NPC). Fractionation of the NPC on discontinuous density gradients of Percoll demonstrated that the NK activity mediated by NPC was associated with cells morphologically characterized as large granular lymphocytes (LGL). Further studies demonstrated that the repeated administration of poly ICLC resulted in significantly higher levels of liver-associated NK activity and total liver-associated LGL as compared to a single injection.

Animals↗
PubMed1985

Changes in number and density of large granular lymphocytes upon in vivo augmentation of mouse natural killer activity.

NK activity of mice as well as humans and rats has been clearly associated with large granular lymphocytes (LGL). To better understand the effects of interferon (IFN) and IFN inducers on natural killer (NK) cells, we have compared the LGL in the spleens of normal and boosted mice. Cells were fractionated by centrifugation on discontinuous Percoll density gradients, and each fraction was tested for NK activity against YAC-1 targets and for the presence of LGL. In vivo treatment with C. parvum (0.7 mg/mouse, i.p., day-3), MVE-2 (25 mg/kg, i.p., day-3), poly I:C (4 mg/kg, i.p., day-3), or IFN (10(5) U/mouse, i.p., day-1) resulted in a marked augmentation and a change of distribution of cytotoxic activity. Most of the NK activity of boosted spleen cells was associated with lower density fractions 1 and 2, whereas active normal spleen cells had somewhat higher density (fractions 2 and 3). In parallel to their increased reactivity, the boosted spleens had a marked increase in the percentage of LGL, particularly in fractions 1 and 2. The augmented activity appeared to be mediated by the LGL, because treatment with anti-asialo GM1 or anti-Thy-1.2 plus complement reduced NK as well as the number of LGL. These results indicate that IFN-mediated boosting of NK activity in the spleen is due to an increase in the lower density LGL, as well as to an increase in the function of preexisting NK cells.

Adjuvants, Immunologic↗
PubMed1984

Radioenzymatic assay of catecholamines: real and apparent losses of labelled product.

In the radioenzymatic assay of catecholamines, using catechol-O-methyltransferase, the yield of labelled product is frequently less than the expected value. This has been attributed by some workers to losses during the periodate oxidation of the O-methylated derivatives. Using spectrophotometric methods, we have demonstrated that there is no oxidative demethylation of the methoxycatecholamines during periodate oxidation. In a novel technique designed to determine the specific activity of small quantities of tritiated S-adenosylmethionine, high performance liquid chromatography with electrochemical detection was used to measure the amount of adrenaline formed from unlabelled noradrenaline, in the presence of phenylethanolamine-N-methyltransferase and tritiated S-adenosylmethionine. As well as the real losses occurring during solvent extraction and thin layer chromatography (demonstrated spectrophotometrically), apparent 'loss' of radiolabelled product may be due to the assumption that the value for the specific activity of the tritiated S-adenosylmethionine and the determination of the product's radioactivity are both absolutely accurate, with no allowance being made for the normal and expected experimental errors in such measurements.

Catechol O-Methyltransferase↗
PubMed1984

Kinetics of enzymatic O-methylation: its value in assays for catecholamines in plasma.

The kinetics of enzymatic O-methylation of catecholamines were studied under conditions like those used in the radioenzymatic assay of plasma catecholamines. Inappropriate Michaelis-Menten kinetics and linear approximations of exponential equations were not used. Mathematical analysis indicated the importance of the ratio of methyl donor (S-adenosylmethionine) to substrate (catecholamine) concentration. If the reaction is incomplete, only a large ratio will allow linear approximations between product formed and initial catecholamine concentration. The use of high-concentration internal standards to correct for plasma interference may give erroneous results by reducing this ratio. Accuracy will be improved by ensuring (a) that S-adenosylmethionine is always greatly in excess of catecholamine, (b) that concentrations of added standards are of the same order as for endogenous catecholamine, and (c) that a high activity of enzyme is used, to allow the reaction to reach completion even in the presence of some inhibition.

Catechol O-Methyltransferase↗