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Biomedical subjects

S K Smith

Publications and source records attributed to S K Smith.

At least 181 records · Page 10Linked to original sources
PubMed1990

The relationship between the length of the base period and population forecast errors.

"The base period of a population forecast is the time period from which historical data are collected for the purpose of forecasting future population values. The length of the base period is one of the fundamental decisions made in preparing population forecasts, yet very few studies have investigated the effects of this decision on population forecast errors. In this article the relationship between the length of the base period and population forecast errors is analyzed, using three simple forecasting techniques and data from 1900 to 1980 for states in the United States. It is found that increasing the length of the base period up to 10 years improves forecast accuracy, but that further increases generally have little additional effect. The only exception to this finding is long-range forecasts of rapidly growing states, in which a longer base period substantially improves forecast accuracy for two of the forecasting techniques."

Americas↗
PubMed1990

A demographic analysis of the population growth of states, 1950-1980.

Factors affecting regional differences in population growth in the United States are explored. "In this study, we estimated the contributions of births, deaths, and migration to changes in population size between 1950 and 1980 for the 48 contiguous states in the United States. We found that population momentum (i.e., the growth that would occur in a closed population if fertility and mortality rates remained constant) had the largest effect on population growth in most states, but that differences in net migration were the major cause of state-to-state differences in growth rates. We also found that net migration has been gaining in importance compared to natural increase as a component of population growth. We expect this trend to continue in coming decades." This is a revised version of a paper originally presented at the 1988 Annual Meeting of the Population Association of America (see Population Index, Vol. 54, No. 3, Fall 1988, p. 429).

Americas↗
PubMed1990

The effects of mefenamic acid and norethisterone on measured menstrual blood loss.

Although there are numerous medical treatments for menorrhagia, in many instances neither the precise diagnosis nor the response to therapy have been assessed objectively. Menorrhagia (menstrual blood loss more than 80 mL per cycle) was diagnosed objectively in 32 (44%) of 72 women with a subjective complaint of heavy menses. All of the 32 women had ovulatory cycles. After random allocation to treatment with either mefenamic acid (500 mg three times daily during menses, N = 17) or norethisterone (5 mg twice daily on days 19-26 of the cycle, N = 15) for two additional cycles, the median menstrual blood loss was reduced from 123 mL (range 86-237) to 81 mL (22-193) (P less than .001) and from 109 mL (81-236) to 92 mL (43-189) (P less than .002) with mefenamic acid and norethisterone, respectively. Apart from a decrease in the median number of days of bleeding, from 7 (5-8) to 5 (3-8) in those women treated with mefenamic acid, no other differences were seen between the groups. We conclude that mefenamic acid and norethisterone were similarly effective in reducing the degree of menstrual blood loss in women with proved menorrhagia, but that 52 and 67% of the women, respectively, remained menorrhagic after 2 months of treatment.

Adult↗
PubMed1989

Examination of parathyroid hormone antisera for the presence of receptor antibodies.

Proteins from bovine kidney membranes were separated by denaturating polyacrylamide gel electrophoresis and blotted onto nitrocellulose paper. The blots were immunostained with parathyroid hormone (PTH) antisera, and the effect of the presence of PTH on immunostaining was determined. Immunostaining of membrane proteins by two specific antisera was altered by PTH. With one antiserum, the immunostaining of two specific proteins (apparent mass 90 and 105 kDa) was prevented by PTH. With the second antiserum the immunostaining of a 150 kDa protein was prevented by the hormone. These effects were strongest with the 90 and 150 kDa proteins and these were investigated further. Antibody binding was prevented either by co-incubation or by preincubation of the blots with PTH, followed by washing and subsequent exposure to the antisera. Concentrations of PTH as low as 1 nM prevented antibody binding to the 90 kDa species, but somewhat higher PTH concentrations were required with the 150 kDa protein. Oxidation of the PTH methionine residues in the amino terminal segment of PTH, and deletion of the first nine residues in the hormone greatly reduced the competition with the 90 kDa protein, but had no effect on immunostaining of the 150 kDa species. The 35-84 fragment of PTH was not a competitor for the 90 kDa species, while the 1-34 fragment was ineffective with the 150 kDa protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Luteinizing hormone releasing hormone agonist for contraception in breast feeding women.

During the period of lactation there is a need for a reliable method of contraception since the suppressive effects of lactation on ovulation decline as the duration of breastfeeding is decreased. The aim of this study was to establish that chronic treatment with a LHRH agonist would prevent ovulation throughout the period of lactation and to evaluate the effects of the treatment on estrogen production, bleeding patterns, and nursing practice. Starting 6 weeks postpartum, nine mothers took 300 micrograms LHRH agonist (buserelin), intranasally once daily for the remainder of the duration of breastfeeding [216 +/- 18 days (mean +/- SEM)]. Urinary excretion of LH, estrone, and pregnanediol was compared to that of nine control breastfeeding mothers. In the control subjects follicular development, as assessed by rises in estrone, was minimal during the first 90 days of the study. Thereafter, phases of estrogen secretion were observed. Ovulation occurred in seven of the nine mothers on one to six occasions; time to first ovulation varied from 90-296 days. In the women taking buserelin, LH and estrone were initially stimulated for 1 and 2 weeks, respectively, then declined to basal levels. No ovulations occurred in the treated group. In six treated mothers only minor fluctuations in estrone were observed during the remainder of agonist treatment. In three subjects more frequent and sustained episodes of estrogen secretion were observed, but in contrast to the controls the rises in estrone were not followed by a typical LH surge or a rise in pregnanediol. Bleeding occurred in eight of the nine of the control mothers on one to seven occasions during the study period. The first bleed in five of the mothers was anovular, while other menstrual bleeds occurred in response to falling levels of pregnanediol. Of the mothers taking buserelin, one was amenorrhoeic, and five had only one light bleeding associated with the initial stimulation of estrone. Of the three women with continued fluctuations of estrone, one had three light bleeds, one experienced frequent spotting, while one had regular bleeding. No other side-effects, such as hot flashes or changes in nursing practices, were reported. Our results indicate that LHRH agonist treatment has the potential to be developed as an acceptable method of contraception during the postpartum period. The duration of treatment may be long enough to have a significant effect on maternal-infant well-being without encountering significant problems associated with low estrogen output.

Administration, Intranasal↗
PubMed1989

The role of cell maturation in the generation of phenotypic heterogeneity in B-cell chronic lymphocytic leukaemia.

B-chronic lymphocytic leukaemia (B-CLL) patients can be ranked along a progression of phenotypes characterized by a decreasing surface expression of CD20, CD21, CD22 and membrane immunoglobulin and a gradual replacement of the high molecular weight (MW) glycoproteins of the leucocyte-common antigen (LC) CD45RA by the lower MW components, including the CD45RO determinant. As CD20, CD21, CD22 and membrane immunoglobulin change during or after B-cell activation, and the CD45RA/CD45RO inversion is implicated in T-cell maturation, the possibility that the phenotypic differences are generated by a maturational diversity of the CLL clones has been investigated by testing the effects of TPA treatment of the leukaemic cells. TPA reduces the level of expression of CD20, CD21, mIg and CD45RA and increases CD45RO binding, thereby minimizing the phenotypic heterogeneity of the CLL clones and causing them to converge towards one end of the natural range. We propose that the phenotypic diversity in CLL is, at least in part, a consequence of maturational diversity where lymphocyte development is disrupted at different stages in different patients.

Antigens, CD↗
PubMed1988

The release of PGF2 alpha and PGE2 from separated cells of human endometrium and decidua.

The capacity of separated glandular and stromal cells from endometrium and first trimester decidua to release prostaglandins (PGs) was studied over 48 hours in culture. Glandular preparations released more PGs than stromal preparations in all tissues. Stromal release of PGs did not alter throughout the cycle or in early pregnancy but the capacity of glandular preparations to release PGs varied considerably. Proliferative glands released most PGF2 alpha and PGE2 followed by secretory glands and decidua. Histamine (10(-5)) stimulated PG release from endometrial and decidual glands but the response of proliferative glands was greatest. Actinomycin D stimulated release of PGF2 alpha and PGE2 from glandular cells of secretory endometrium and decidua. These results suggest that in vitro release of PGs is suppressed after ovulation and is in part due to inhibition of PG release by a protein or proteins synthesized in the glandular fraction of secretory endometrium or decidua.

Dactinomycin↗
PubMed1988

Effect of platelet-activating factor on the release of PGF-2 alpha and PGE-2 by separated cells of human endometrium.

Synthetic platelet-activating factor (PAF-acether, 1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) caused a dose-dependent increase in the synthesis of prostaglandin (PG) E-2 by an enriched glandular, but not stromal, fraction of human endometrium removed in the secretory phase of the menstrual cycle. PAF-acether did not alter the synthesis of PGF-2 alpha by this fraction and consequently there was a significant reduction in the ratio of the amounts of PGF-2 alpha/PGE-2 released by the cells into the culture medium. The preimplantation human embryo secretes PAF, and these findings may have relevance to the local maternal recognition of pregnancy.

Cells, Cultured↗
PubMed1988

The fibrogenic response of adult rat lung to continuous propranolol treatment.

Fibrogenesis is a common pulmonary response to injury, which is usually preceded by other severe reactions, including inflammation, fluid exudation, and alveolar epithelial damage and proliferation. The purpose of this study was to examine the morphologic effects on the distal lung of a continuous propranolol treatment. Adult male rats were treated, via a subcutaneous osmotic pump, with a continuous (approximately 0.5 mg/hour) dose of propranolol HCl, a potent wide range beta-adrenergic blocking agent, in saline, or saline alone. The animals were killed after one week or three weeks. Electron microscopy of the lungs of the propranolol-treated animals revealed a dramatic increase in the prominence of interstitial cells and fibers of the alveolar septa, along with focal thickening of endothelial cells and some morphologic changes in type II alveolar epithelial cells. In some animals an analysis of total protein content, as well as 3H-proline incorporation into total protein and collagen was undertaken. The results of this study indicated a significant increase in total protein content and proline incorporation into collagen in the lungs of animals treated for seven days with continuous propranolol. There was no evidence of stimulated blood cells, macrophages, edema or severe epithelial damage. This study provides morphologic evidence that continuous treatment with moderate levels of propranolol results in a fibrogenic response in the peripheral lung, in the absence of typical hallmarks of severe pulmonary damage.

Animals↗
PubMed1988

Child abuse and neglect: a diagnostic guide for the optometrist.

Since approximately 40% of all physically abused children have ocular complications, it is increasingly important for optometrists to be prepared for an encounter with a child patient who has been abused. This review of the literature was undertaken to develop a diagnostic guide for the optometrist in face of a growing incidence of child abuse. It describes different types of abuse and their physical, emotional and behavioral manifestations. A special emphasis has been placed on head trauma and associated ocular signs. A list of state child protective services agencies, and how to contact them, is included.

Child↗
PubMed1988

Stability over time in the distribution of population forecast errors.

A number of studies in recent years have investigated empirical approaches to the production of confidence intervals for population projections. The critical assumption underlying these approaches is that the distribution of forecast errors remains stable over time. In this article, we evaluate this assumption by making population projections for states for a number of time periods during the 20th century, comparing these projections with census enumerations to determine forecast errors, and analyzing the stability of the resulting error distributions over time. These data are then used to construct and test empirical confidence limits. We find that in this sample the distribution of absolute percentage errors remained relatively stable over time and data on past forecast errors provided very useful predictions of future forecast errors.

Demography↗
PubMed1987

Cytoplasmic enzyme patterns in isolated hamster pulmonary alveolar type II cells.

Three cytoplasmic enzyme patterns were studied in pulmonary alveolar type II cells isolated from normal adult hamster lung: lactate dehydrogenase (total and isoenzymes), peroxidase, and beta-N-acetylglucosaminidase. Enzyme patterns of freshly-isolated type II cells were found to be different from those of freshly-isolated pulmonary hamster fibroblasts. After both types of cells had been cultured for seven days, no difference in cytoplasmic enzyme patterns remained. Lactate dehydrogenase isoenzyme patterns for type II cells were different from those obtained from polymorphonuclear leukocytes and alveolar macrophages. These data may be useful in detecting sources of lung injury by assessment of enzyme patterns in bronchoalveolar lavage fluid.

Acetylglucosaminidase↗
PubMed1987

The effect of estradiol-17 beta and actinomycin D on the release of PGF and PGE from separated cells of human endometrium.

Estradiol-17 beta selectively stimulated the release of PGF from separated glandular but not stromal cells of human secretory endometrium (p less than 0.025) but had no effect on PGF release from either type of cells obtained from proliferative endometrium. PGE release was not affected by estradiol-17 beta. Actinomycin D did not antagonise the effect of estradiol-17 beta on PGF release from secretory, glandular cells. Basal release of PGF from these cells was stimulated by actinomycin D alone (100 ng/ml) (p less than 0.025) and PGE release stimulated in the presence of estradiol-17 beta. Actinomycin D had no effect on PGF or PGE release from proliferative endometrium. These findings suggest that estradiol-17 beta stimulates PGF release by a mechanism that does not affect PGE release and which is not dependent on the synthesis of new protein. The basal release of PGF and PGE by glandular cells of secretory endometrium in vitro is regulated by protein/proteins which reduce PG release.

Cell Separation↗