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Biomedical subjects

S R Young

Publications and source records attributed to S R Young.

At least 37 records · Page 2Linked to original sources
PubMed1994

PAX6 gene dosage effect in a family with congenital cataracts, aniridia, anophthalmia and central nervous system defects.

The human eye malformation aniridia results from haploinsufficiency of PAX6, a paired box DNA-binding protein. To study this dosage effect, we characterized two PAX6 mutations in a family segregating aniridia and a milder syndrome consisting of congenital cataracts and late onset corneal dystrophy. The nonsense mutations, at codons 103 and 353, truncate PAX6 within the N-terminal paired and C-terminal PST domains, respectively. The wild-type PST domain activates transcription autonomously and the mutant form has partial activity. A compound heterozygote had severe craniofacial and central nervous system defects and no eyes. The pattern of malformations is similar to that in homozygous Sey mice and suggests a critical role for PAX6 in controlling the migration and differentiation of specific neuronal progenitor cells in the brain.

Abnormalities, Multiple↗
PubMed1992

Comparison of the effects of moist and dry conditions on the process of angiogenesis during dermal repair.

The effect of moist and dry conditions on the process of angiogenesis during dermal repair was investigated. The moist conditions were achieved by covering excised wounds on porcine flank skin with the adhesive polyurethane dressing Opsite and dry conditions were achieved by exposure to air through dry gauze dressings. Angiogenesis was assessed during the period from 3 to 60 d after injury. Quantitative studies, using computerized image analysis, were carried out on microfocal x-ray images of skin sections whose blood system had been perfused in vivo with a radio-opaque medium. The analytical technique yielded information with regard to vessel number per wound and also the area occupied by blood vessels per unit wound area. Three regions were assessed in each wound bed: upper zone, just below the surface of the wound; the lower zone, just above the base of the wound bed; and the middle zone, midway between the other two zones. The results showed that the wounds maintained in a moist environment revascularized at a greater rate than those maintained in a dry environment. This was apparent in all of the zones of the wound bed examined. The development of new vessels occurred in a more orderly manner in the moist wounds. There was an early increase in vessel number rising to a peak around days 3-5, then a gradual decrease in number starting around day 7. In contrast, in the dry wounds the development of blood vessels was less rapid. Peak vessel number in the upper zone was significantly less than that achieved in the moist wounds, and was not reached until 7 d after injury. The decrease in vessel number from the peak was less rapid in the dry wounds, suggesting that there was a delayed entry into the remodeling phase in comparison with the moist wounds. The results also showed that the total percentage area of the wound bed occupied by blood vessels was greater in the moist wounds than the dry wounds from 3 d after injury until day 7. This level of vascularization was maintained beyond 7 d after injury even when the vessel number in the moist wounds was significantly less than in the dry wounds, suggesting that the vessels in the moist wounds were larger and, presumably, more mature. In general, moist wounds showed a more rapid decline towards uninjured skin levels of vascularization than dry wounds.

Animals↗
PubMed1992

A Y-associated allele may be characteristic of certain ethnic groups in Asia.

The probe 47z detects DNA polymorphisms on both the X and Y chromosomes. Blood samples were collected from Korean, Chinese, Jewish, Caucasian and Negro populations and polymorphisms of both loci were compared with findings previously reported in Japanese. Both Y1 and Y2 alleles were detected in Japanese and Koreans. However, only the Y1 allele was detected in each of the other populations. Although, both X1 and X2 alleles were detected in all examined populations, the frequency of the X2 allele was very low among Negroes.

Alleles↗
PubMed1991

Single-center comparison of results of 1000 prenatal diagnoses with chorionic villus sampling and 1000 diagnoses with amniocentesis.

Large multicenter studies have confirmed the safety and accuracy of chorionic villus sampling as a prenatal genetic diagnostic procedure, but there have been few single-center evaluations. We report our experience with 1000 consecutive chorionic villus sampling procedures compared with 1000 consecutive amniocentesis procedures during the same period. The procedures were performed by the same genetic counselors, sonographers, obstetricians, and laboratory personnel. Indications for referral, demographic characteristics of patients, numbers of attempts per patient, fetal loss rates, laboratory results, and evaluation of accuracy are included. Analysis of all data suggests that chorionic villus sampling is a safe and accurate alternative to amniocentesis in our community-based teaching hospital.

Adult↗
PubMed1991

High time resolution fluorescence imaging with a CCD camera.

We have built a high speed, sensitive camera system capable of capturing sequences of low-light level images synchronized with recordings of membrane potential. The camera system is based on a cooled, scientific grade CCD camera controlled by a PC/AT computer. It can take 100 frames/sec of 18 X 18 element images and 40 frames/sec of 50 X 50 element images with no lag in response to step changes in light intensity. High accuracy and dynamic range of the measurements result from the fact that light levels of the picture elements are digitized with 12 bit accuracy with intrinsic camera noise levels typically less than 1/10,000 of the maximum detectable light level. We have used this system to record calcium dependent fura-2 fluorescence transients in the dendrites of cerebellar Purkinje cells and from different regions of leech neurons in segmental ganglia or isolated in culture.

Animals↗
PubMed1991

Pregnancy termination because of chromosomal abnormalities: a study of 26,950 amniocenteses in the southeast.

A regional study was done to investigate the outcome of chromosomally abnormal pregnancies with respect to the parental decision to continue or to terminate the pregnancy. Fourteen medical centers in the southeastern United States contributed data on 26,950 amniocenteses. In 416 cases (1.54%), cytogenetic abnormalities were reported. Of 378 singleton pregnancies in which a cytogenetic abnormality was reported and for which information regarding pregnancy outcome was available, the decision to terminate the pregnancy was made in 276 (73.02%). When the chromosomal abnormality was autosomal in nature, 240 of the 293 pregnancies (81.91%) were terminated, as compared to 36 of the 85 pregnancies (42.35%) affected with a sex chromosomal abnormality. Pregnancies involving the most common autosomal trisomies (21, 18, and 13) were terminated at a rate of 92% to 95%. No significant difference in the rate of abnormality or in the rate of pregnancy termination existed between the 14 centers. Our findings reflect the largest series of amniocentesis results collected to date.

Abortion, Induced↗
PubMed1991

Comparison of the effects of semi-occlusive polyurethane dressings and hydrocolloid dressings on dermal repair: 1. Cellular changes.

The effects on dermal repair of two wound dressings, one the semi-occlusive polyurethane sheet Opsite, the other the hydrocolloid Granuflex, were compared in full-thickness excised lesions on porcine skin during the period from 5 d to 6 months after injury. Quantitative studies were made of changes in the populations of polymorphonuclear leucocytes, macrophages, fibroblasts, and endothelial cells. The progress of repair in the wounds covered with the semi-occlusive dressing showed a decrease in the number of inflammatory cells (polymorphonuclear leukocytes and macrophages) from 5 to 60 d, whereas the number of proliferative phase cells (fibroblasts and endothelial cells) increased from 5 to 7 d. The total cellularity per unit area showed an increase between 5 and 7 d, that is, during the proliferative phase of repair, and then progressively decreased as the proliferative phase was succeeded by the remodeling phase. In contrast, the repair process in the hydrocolloid-dressed wounds was more complex. The number of inflammatory cells remained relatively high throughout and there were consistently fewer endothelial cells present throughout. Fibroblast number showed an initial fall from 5 to 14 d but then started to increase in number from 21 to 60 d. This chronic inflammatory reaction appeared to be in response to particulate matter that had been incorporated into the wound bed and hypodermis, and was still apparent 6 months after injury, when hydrocolloid particles were detectable microscopically in the hypodermis.

Animals↗
PubMed1991

Synaptic integration at a sensory-motor reflex in the leech.

1. In the medicinal leech the distribution of synapses from the pressure sensory (P) neurone to the annulus erector (AE) motoneurone and the site of impulse initiation in the AE cell were determined to understand better the integration of sensory inputs by the motoneurone. 2. The axon of the AE cell bifurcates before leaving the ganglion. Laser photoablation experiments indicated that the axon proximal to the bifurcation is inexcitable. Two techniques, laser photoablation and measurement of impulse timing, each located the site of impulse initiation at the bifurcation. 3. The medial P cell makes a monosynaptic connection with the AE cell, eliciting an excitatory postsynaptic potential (EPSP) of 1-3 mV amplitude recorded in the AE cell soma. 4. Intracellular injection of dyes into separate cells showed that P cell branches appear to contact AE cell branches both ipsilaterally and contralaterally. Laser photoablation of selected portions of the P and AE cells' axons revealed functional contacts on both sides. 5. The primary axon bifurcation of the AE cell is the site of integration of synaptic potentials that spread passively from both sides of the ganglion. These summed synaptic potentials account for the concerted activity of the two AE cells in each ganglion.

Action Potentials↗
PubMed1991

ASHG/NSGC activities related to education. The doctoral degree in genetic counseling: attitudes of genetic counselors.

All 565 full members of the National Society of Genetic Counselors were surveyed in September 1989 to assess their attitudes toward a potential doctoral degree in genetic counseling. The usable return rate was 59.6% (337/565) of the full membership. One hundred eighty (54.4%) respondents indicated a need for a doctoral degree in genetic counseling, 101 (30.5%) were undecided as to the need, and 50 (15.1%) did not see a need for such a degree. One hundred forty-seven (44.3%) respondents indicated their individual interest in pursuing a doctorate in genetic counseling, 109 (32.8%) would not pursue such a degree, and 76 (22.9%) were undecided. Beyond the generally accepted feeling that genetic counseling should expand as a professional field, the reasons cited most often for seeking the Ph.D. in genetic counseling were professional recognition, a desire to specialize in a particular area, and greater depth of knowledge. The study revealed a strongly positive attitude, among full members of the NSGC, toward establishment of a doctoral degree in genetic counseling.

Adult↗
PubMed1990

Effect of therapeutic ultrasound on the healing of full-thickness excised skin lesions.

The effect of therapeutic ultrasound on the healing of the dermis of full-thickness excised lesions made in the flank skin of adult rats was assessed quantitatively by means of differential cell counts made in sections of the wound bed five and seven days after injury. Wounds were either sham-treated (control group) or exposed to pulsed ultrasound (2 ms on, 8 ms off) at an intensity of 0.1 W cm-2 SATA (frequency either 0.75 MHz or 3.0 MHz). By five days after injury, ultrasound-treated wounds contained more extensive granulation tissue, fewer polymorphonuclear leucocytes (polymorphs) and macrophages, and more fibroblasts (aligned in a manner conducive to efficient wound contraction) than the sham-irradiated controls. By seven days after injury there was no significant difference in cellularity between the controls and the ultrasonically-irradiated wounds. The results obtained suggest that ultrasound therapy can be useful in accelerating the inflammatory and early proliferative stages of repair.

Animals↗
PubMed1990

The effect of therapeutic ultrasound on angiogenesis.

The effect of therapeutic ultrasound on the formation of new blood vessels in full-thickness excised lesions in the flank skin of adult rats was assessed quantitatively using microfocal x-ray techniques. Wounds were either sham-treated (control group) or exposed to ultrasound for 5 min daily at an intensity of 0.1 W/cm2 SATA (frequency either 0.75 MHz or 3.0 MHz). By 5 days after injury there were more blood vessels in equivalent regions of the granulation tissue of the ultrasound-treated wounds than in the control wounds. This suggested that the ultrasound-treated wounds were at a more advanced stage in the repair process. By 7 days after injury there was no significant difference in blood vessel number between the three groups.

Animals↗
PubMed1990

Macrophage responsiveness to therapeutic ultrasound.

Macrophages are a source of many important growth factors which can act as wound mediators during tissue repair. The aim of this work was to find out if levels of ultrasound which accelerate repair could stimulate the release of fibroblast mitogenic factors from an established macrophage-like cell line (U937). The U937 cells were exposed in vitro to continuous ultrasound at a space average, temporal average intensity of 0.5 W/cm2 at either 0.75 MHz or 3.0 MHz, for 5 min. The macrophage-conditioned medium was removed either 30 min or 12 h after exposure, and placed on 3T3 fibroblast cultures. Fibroblast proliferation (defined here as increase in cell number) was assessed over a 5-day period. The results showed that 0.75 MHz ultrasound appeared to be effective in liberating preformed fibroblast affecting substances from the U937 cells, possibly by producing permeability changes, whereas 3.0 MHz ultrasound appeared to stimulate the cell's ability to synthesize and secrete fibroblast mitogenic factors.

Animals↗
PubMed1989

Elevated blood serotonin in autistic probands and their first-degree relatives.

Whole blood serotonin levels and platelet counts were studied in 14 families, representing 57 family members and 15 probands who met DSM III criteria for infantile autism. High serotonin appeared to segregate in families. When two parents had high serotonin, the serotonin level in their offspring was twice the parental level. When one parent had high serotonin, the serotonin level in the offspring approximated the level of serotonin in either the high serotonin parent or the low serotonin parent. For the case where both parents had low serotonin, in one family the children had low serotonin and in a second family, high serotonin levels were present in the autistic proband, and a sibling with severe mental retardation. Mean serotonin levels were higher for both male and female, autistics and family members, in the four black families than in the 10 Caucasian families.

Adolescent↗
PubMed1989

Analysis of fetal loss after transcervical chorionic villus sampling--a review of 719 patients.

Chorionic villus sampling was performed under real-time ultrasonographic direction on a study group of 719 patients from September 9, 1985, through May 5, 1988. Follow-up of 714 of these patients who would have reached 28 weeks' gestation on September 1, 1988, revealed "an unintended" abortion rate of 4.1% by 20 weeks' gestation. Nine patients had a fetal loss less than 4 weeks after the procedure; 19 had losses up to 12 weeks after the procedure and before 20 weeks' gestation. This study revealed a significantly increased risk of fetal loss with an increase in the number of catheter insertions (p less than 0.001). The risk of fetal loss after one sampling attempt was 3%, 7.8% after two attempts, and 14.3% after three attempts.

Abortion, Spontaneous↗
PubMed1989

The significance of membrane changes in the safe and effective use of therapeutic and diagnostic ultrasound.

The cellular changes, such as alterations in motility and the stimulation of synthesis and secretion, induced by relatively low intensities of therapeutic ultrasound (e.g. 500 mW cm-2, SAPA; 100 mW cm-2 SATA) are primarily non-thermal in origin. They appear to be associated with changes in the permeability of the cell (plasma) membrane and in the transport of ions and molecules across it, effects which have been demonstrated in cells irradiated in suspension. In epithelial tissues, both in vitro and in vivo, it has been demonstrated that not only the cellular membrane transport pathways but also the paracellular or intercellular pathways are affected. Although membrane-mediated effects can be of value therapeutically, they could produce adverse effects if they were to occur during development, for the reception and transmission by the membrane of environmental signals are involved in determination of the fate of each cell. Determination is followed by selective gene expression and differentiation, that is, by the progressive increase in structural complexity brought about by the acquisition of specialised characteristics by various cell groups. Most cells of early embryos are ionically coupled via gap junctions which provide an intercellular pathway for electrochemical signalling and the maintenance of the concentration gradients which provide the cells with positional information. Differentiation of the cells varies according to their location with respect to these gradients. Increase in the intracellular concentration of calcium ions, which has been shown to occur after exposure to therapeutic levels of ultrasound, can decrease the permeability of gap junctions and uncouple cells, in the manner which occurs when they differentiate. Ultrasonically induced increases in calcium ion concentration are thus of considerable clinical significance, since they could affect differentiation and consequently histogenesis. Modification of plasma membrane permeability and transport properties, resulting in changes in the availability and activity of second messengers such as free calcium ions, can have profound effects on cell behaviour. Calcium channels appear to be the first channels to develop in the cell membranes of embryos, and internal calcium ion concentration is known to affect the synthesis of fetal proteins. Although generally reversible at intensities of less than 500 mW cm-2, changes in membrane permeability, particularly to calcium ions, could, if prolonged, have undesirable side effects not only on embryogenesis but on late prenatal and postnatal development. It is therefore recommended that the environmental conditions, thresholds, and mechanisms involved in the production of such changes be determined, so that they can be avoided when ultrasound is used diagnostically on sensitive targets such as embryos and fetuses.

Animals↗
PubMed1989

Utilization of amniocentesis and chorionic villus sampling by South Carolina women 35 years of age and older.

An increase in utilization of prenatal diagnosis was observed from 1985 to 1986 in South Carolina. The overall rate of 39.9% for 1986 is comparable with other areas of the U.S. Utilization was correlated with geographic residence, race, and referral source. While there was considerable variation in prenatal diagnostic test utilization between counties in South Carolina, overall utilization rates were reasonably high and continued to increase from 1985 to 1986. It will be interesting to see what effect CVS has on overall utilization rates as this new procedure becomes more established throughout the state.

Adult↗