Biomedical subjects

L A Johnson

Publications and source records attributed to L A Johnson.

222 records · Page 13Linked to original sources

PubMedDate not supplied

Antepartum bed rest: effect upon the family.

OBJECTIVE: To identify the effects of antepartum bed rest upon the family. DESIGN: Descriptive, retrospective survey. PARTICIPANTS: A national random selection of 89 women who had been prescribed antepartum bed rest in the hospital or at home and who contacted a high-risk pregnancy support group for information. MAIN OUTCOME MEASURE: An open-ended questionnaire. RESULTS: Families experienced difficulty assuming maternal responsibilities, anxiety about maternalfetal outcomes, and adverse emotional effects on the children. Child care was managed by various people across time. Child care problems included negative reactions from the children, concern about the quality of the provider, and maternal worry about care. Families also experienced financial difficulties, the majority of which were not compensated by insurance or work benefits. Almost all, 96.6%, families received some type of support during bed rest. Instrumental support was the most commonly received; however, emotional support was considered the most helpful. The least helpful type of support was that which was unreliable. The primary providers of support to the family were parents and family, followed by friends. The women reported that health care providers offered minimal support to the family. CONCLUSION: Despite support, antepartum bed rest creates difficulties that affect the entire family and its finances.

Adaptation, Psychological↗

PubMedDate not supplied

Two-dimensional electrophoresis and densitometric analysis of solubilized bovine sperm plasma membrane proteins detected by silver staining and radioiodination.

Bovine sperm plasma membranes were extracted with deoxycholate and subjected to two-dimensional gel electrophoresis. Proteins were visualized either by silver staining or autoradiography using 125I. When 1.5-2.0 micrograms of protein extract was applied to the first-dimension get, 250 spots could be detected by autoradiography. Thirty micrograms of protein was required to obtain spot visualization using silver strain, revealing more than 500 spots on the gel. These data establish the limit under which two-dimensional electrophoresis can be used in conjunction with flow cytometric sorting of sperm for the analysis of possible sex-specific membrane differences. The necessity of orienting sperm as they past the laser in the cell sorting system reduces throughput; thus, the number of sperm sorted within a given time is limited. It is suggested that autoradiography will allow the flow cytometer to be used in a time-efficient manner. Longer sorting times would be required to obtain sufficient sample to analyze total protein composition.

Animals↗

PubMedDate not supplied

Regulation of IFN-gamma production following 2B4 activation in human NK cells.

IFN-gamma is a cytokine that regulates various functions of the immune system. The major producers of IFN-gamma are T cells and NK cells. 2B4 is a novel activating receptor expressed on all human NK cells, a subset of CD8+ T cells, monocytes and basophils. Activation of human NK cells through surface 2B4 enhances NK cell cytolytic function and secretion of IFN-gamma. We have examined the regulation of IFN-gamma production by the human NK cell line YT upon activation through surface 2B4. Our data indicate that ligation of surface 2B4 by mAb C1.7, that specifically recognizes 2B4, induces transcriptional activation of IFN-gamma. Partial inhibition of transcription did not prevent the transcriptional upregulation of IFN-gamma. S1 nuclease protection analysis indicated that transcriptional activation as well as mRNA stability may account for the increased production of IFN-gamma by human NK cells following 2B4 stimulation.

Actins↗

PubMedDate not supplied

Dual DNA staining assessment of bovine sperm viability using SYBR-14 and propidium iodide.

A new membrane-permeant DNA stain, SYBR-14, was used in combination with propidium iodide (PI) to estimate the proportion of living sperm in bovine semen. The SYBR-14 stained living sperm while PI only stained degenerate cells that had lost their membrane integrity. Staining with SYBR-14 resulted in the nuclei of living sperm fluorescing bright green. Aliquots containing nearly all living bovine sperm were prepared using glass wool/Sephadex filtration to remove dead and damaged cells. A portion of this filtered sample was killed by unprotected freeze-thawing and used to provide mixed aliquots containing known ratios of living and dead sperm. Flow cytometry was used to assess the green and red fluorescence of these mixtures. The percentages of living sperm, as determined by the log of green fluorescence, were 85.1, 68.8, 39.8, 20.7, and 1.4 for ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 of the filtered, killed mixtures. Also, bovine semen was diluted 1:60 in HEPES-0.1% bovine serum albumin and incubated for 0, 3, 6, and 24 hours at 36 degrees C to assess changes in cell viability. As cell death occurred during this incubation period, a relatively rapid transition of staining from green to red occurred as sperm died. Three replicates of cryopreserved sperm from six bulls were also examined using SYBR-14 and PI to assess the proportion of living and dead cells. Flow cytometric analyses of these samples, which had been processed and stored in homogenized milk, indicated that this stain combination was useful in assessing the quality of cryopreserved sperm. The combination of SYBR-14 and PI was determined to be an effective tool for assessing the viability of fresh or cryopreserved sperm.

Animals↗

PubMedDate not supplied

MR quantification of cerebral ventricular volume using a semiautomated algorithm.

PURPOSE: A semiautomated border identification algorithm, insensitive to user bias, is evaluated for accuracy and speed in the measurement of ventricular volumes from three-dimensional MR images. METHODS: A three-dimensional gradient-echo technique was implemented on a Signa clinical imaging system. Data from phantoms and patients were analyzed for volume using a segmentation algorithm designed with: 1) correction for partial volume averaging; 2) insensitivity to user bias; and 3) speed. Accuracy, precision, and intra- and interobserver variability were determined. RESULTS: Average error for phantom studies was 4% to 6%, or 1 to 2 cc across the volumes, which ranged from normal to mild hydrocephalus (< 60 cc). Patient studies showed intra- and interobserver error of 2.3% and 7.8%, respectively. The correction for partial volume averaging resulted in a threefold decrease in error. Data were acquired and reconstructed within 7 minutes. Experienced radiologists required less than 15 minutes to perform each analysis. CONCLUSIONS: This algorithm allows accurate measurement of ventricular volumes in an efficient, minimally supervised manner.

Adult↗

PubMedDate not supplied

Gender preselection in mammals: an overview.

Recent advances in the separation of X and Y chromosome bearing spermatozoa have led to the availability of a method (Beltsville Sperm Sexing Technology) to preselect the sex in several mammals. Progeny using this procedure have been produced in cattle, sheep, swine and laboratory animals. Mammalian sperm are inherently different in that the X sperm carries from 2.8 to 7.5% more DNA than the Y sperm. Individual sperm DNA can be determined and used as the differentiating characteristic with flow cytometry and cell sorting instrumentation especially modified to measure small amounts of DNA in sperm. The process utilizes the fluorochrome Hoechst 33342 to bind to the DNA. The relative DNA is measured by passing the living sperm through a laser beam and collecting the light energy from the individual sperm. Data is acquired and used to select the particular sperm for deflection into collection tubes. The proportions of sorted X and Y sperm in each tube can be validated by reanalyzing an aliquot for DNA content. This value is then used to predict the outcome of fertilization and subsequent gestation. The sorted sperm are used to inseminate eggs via in vitro fertilization (IVF) or by surgical insemination into the oviduct or the uterus of appropriate females. Sperm are sorted at the rate of 0.5 million per hour for most species with the expectation of 90% or greater of one sex or the other being born. Progeny in cattle using IVF have been produced at greater than 90% accuracy. Rabbits have produced greater than 90% females using this process. Progeny produced from pigs average 85% for one sex or the other. All progeny produced (N = or > 300) have exhibited completely normal morphological appearance and normal reproductive function. Because of the inability to obtain large numbers of sorted sperm in a short amount of time, the technologies use for regular artificial insemination would not be practical in most domestic species. This sexing technology however is very applicable where IVF, intrauterine or intratubal insemination are convenient means for producing offspring. In addition, the recent advent of ultrasound guided insemination in cattle may provide and opportunity to use this technology for much lower numbers of sperm per insemination than previously thought possible. Using less than 2 x 10 sorted X or Y sperm would move the technology one step closer to practicality.

Animals↗