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Biomedical subjects

J H Priest

Publications and source records attributed to J H Priest.

At least 55 records · Page 3Linked to original sources
PubMed1983

Branched-chain ketoacid dehydrogenase activity and growth of normal and mutant human fibroblasts: the effect of branched-chain amino acid concentration in culture medium.

We investigated changes in cell growth and branched chain ketoacid dehydrogenase (BCKD) activity by varying the concentrations of branched-chain amino acids (BCAAs) in culture medium of diploid fibroblasts from humans with normal BCKD and with impaired enzyme function. For logarithmic growth the two cell populations required similar minimal concentrations (0.05 mM) for each of leucine, isoleucine, and valine tested together. At confluency (saturation density) mutant cells grew less well to the extent of 30 to 40% in the highest concentrations of BCAAs that could be tested, 20.8 mM. BCKD activity was not changed by growth of normal or mutant cells in the absence of BCAAs. This enzyme activity was increased in normal but not mutant cells by growth in 20.8 mM BCAAs. These studies suggest the following: (1) BCKD mutant fibroblasts in culture slow their growth rate in response to high concentrations of BCAAs; (2) the growth disadvantage for mutant cells in high concentrations of BCAAs may be useful to select for enzyme normal hybrids derived when cells with two different mutations affecting BCKD are fused; (3) the increase of BCKD activity in normal but not mutant cells grown in high concentrations of BCAAs can distinguish these phenotypes more precisely in humans; and (4) the mechanism of BCKD stimulation in normal cells grown in high concentrations of BCAAs remains to be explained but can be pursued further with the cell culture conditions described.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1983

Characterization of hCG regulation in cultured human amniotic fluid cells: II. Mechanisms for stimulation.

We showed previously that sodium butyrate stimulated human chorionic gonadotropin (hCG) measured by radioimmunoassay of medium from human second trimester amniotic fluid cell cultures, termed AF cells. We now find that stimulation of hCG in the presence of sodium butyrate takes as long as 20 h. When AF cells are preincubated with sodium butyrate, hCG levels increase in direct relation to length of the preincubation period. These findings suggest that elevation of hCG is not due merely to a release of hormone from the cells. Addition of cycloheximide or Actinomycin D inhibited protein synthesis and RNA synthesis, respectively, and prevented the stimulation of hCG by sodium butyrate. These results lend support for a mechanism of regulation involving protein and RNA synthesis, the increase in hCG levels being due to new synthesis of the hormone. Other agents reported to influence hCG production by different types of cell cultures include dibutyryl cyclic AMP, epidermal growth factor (EGF), methotrexate, and hydroxyurea. Dibutyryl cyclic AMP and EGF have no effect on hCG production in our AF cells: methotrexate causes a minimal increase, hydroxyurea causes a further increase, but sodium butyrate has the strongest stimulatory effect. We conclude that amniotic fluid cells in culture are susceptible to environmental agents capable of modulating synthesis of hCG by mechanisms involving synthesis of RNA and protein.

Amniotic Fluid↗
PubMed1983

HLA typing of cultured amniotic fluid cells.

HLA typing was performed on 18 cultures of human amniotic fluid cells using cytotoxicity and absorption technics. Confirmation of antigen assignments was obtained in nine of ten instances, where HLA typing also was performed on cord blood. Three major problems were encountered in performing these studies: (1) complement cytotoxicity, (2) false-positive reactions, and (3) false-negative reactions. False-positive and false-negative reactions occurred more frequently with sera defining HLA-B locus specificities than with sera defining HLA-A locus specificities. Absorption studies were helpful in making antigen assignments when false reactions occurred. Preliminary studies suggest that the frequency of false-positive reactions can be decreased by absorbing HLA typing sera with antigen-negative amniotic fluid cultured cells, buffy coat, or platelets. Accurate antigen assignment is difficult when parental HLA types are unavailable.

Absorption↗
PubMed1982

DNA replication sequence in a dicentric (functionally monocentric) X chromosome formed by the joining of two X chromosomes at region p22.

In this study we used densitometry to evaluate DNA replication kinetics in a rearranged chromosome formed by the joining of two X chromosomes at region p22. No 45X mosaicism is present in peripheral blood or fibroblast cultures. The patient has primary amenorrhea, short stature, and gonadal dysgenesis. The sequence of replication in the majority of cells is p11, q11, q13, q22-24, q12, p22, q26, q28, q27, q25, and p21, q21. Thus p11 is the earliest region to replicate, and q21 is the last. In 66% of 127 cells analyzed, the replication pattern is asymmetric, and bands q12, q26, and q28 are most likely to be out of phase on the two sides of the breakpoint. We find that band p22 has a delay of replication compared to an abnormal X derived from two X chromosomes joined at the q23 region previously reported by us. Structural rearrangement may therefore delay replication in the region of the break.

Adult↗
PubMed1981

The characterization of hCG regulation in cultured human amniotic fluid cells.

The media from primary cultures and subcultures of second trimester human amniotic fluid (AF) cells were assayed by radioimmunoassay to quantitate production of human chorionic gonadotropin (hCG). Primary AF cultures produce more hCG per cell than do the corresponding subcultures. Sodium butyrate (2mM) stimulates AF subcultures to produce 5-13 times more hCG per cell or per mg of cellular protein than do untreated subcultures. This stimulatory effect of sodium butyrate is dose dependent between 0 and 5 mM. Addition of sodium butyrate 24 hours after subculture, while stimulating production of hCG during the subsequent 3 days, also results in fewer cells and less protein per culture. This effect on cell growth is also dose-dependent. Previous investigators have proposed that the stimulation of hCG by sodium butyrate in other types of cell cultures is due to an effect of that agent on culture growth. Therefore, in these studies AF cells are allowed to grow to confluency before sodium butyrate was added. Production of hCG was stimulated by sodium butyrate about four-fold during the next 5 days although no significant changes were observed either in number of cells or amount of cellular protein per culture. These results suggest that stimulation of hCG by sodium butyrate is not dependent on its effect on growth of the cultures.

Amniotic Fluid↗
PubMed1980

Acceptance of amniocentesis by low-income patients in an urban hospital.

A study was made of increased accessibility of genetic services to low-income obstetric patients in Atlanta, Georgia. The proportion of black patients averaged 83%. Of 522 patients counseled from August, 1976, through 1978, 157 were offered amniocentesis, and 95 (61%) elected the procedure. For most of the patients (120, or 76%) who were eligible for amniocentesis, age (greater than or equal to 35 years at delivery) was an indication; and of these, only six (5%) had any prior knowledge of genetic risk. During the same time interval, 188 patients over 35 years of age who initiated prenatal care too late for prenatal diagnosis were counseled in the hospital after delivery; 101 (54%) indicated that they would have accepted amniocentesis. The conclusion was that (1) genetic services are acceptable to this socioeconomic group, and (2) accessibility and publicity are needed to promote utilization in this population.

Amniocentesis↗
PubMed1980

Limitations of amniography in the prenatal diagnosis of spina bifida.

A fetus with an open, noncystic myelomeningocele was detected at the 22nd week of gestation in a woman monitored for advanced maternal age. The lesion could not be demonstrated on amniography. In 13% of published reports amniography failed to detect significant spina bifida lesions. This false-negative rate seems related to the noncystic nature of some neural tube defects at midgestation.

Amniotic Fluid↗
PubMed1980

Densitometric and visual measurements of human chromosome 21.

The finding of heteromorphisms in certain regions of human chromosomes is useful in chromosome identification, especially in the study of the origin of nondisjunction. Quantitation of heteromorphisms in the smaller human chromosomes is theoretically valuable but remains technically difficult. In this paper we evaluate two methods for quantitation of human chromosome 21--visual densitometric measurement of Q-banded 34-mm negatives. Thirteen parameters are defined for chromosome 21. We find three of them to show less variability between different measurements of the same cell and from cell to cell in the same individual: (1) the centromere index, defined as the ratio of length of the satellite, stalk, and short arm to the length of the satellite, stalk and short and long arms; (2) the ratio of length of the satellite to the length of the total heteromorphic region of the short arm; and (3) the ratio of the short arm intensity to the intensity of band q21. Another parameter, the ratio of satellite intensity to the intensity of band q21, is reproducible by visual measurement but not by densitometry. Based on these studies we conclude that densitometry is not necessarily better than visual quantitation of the heteromorphic region of chromosome 21.

Chromosome Banding↗
PubMed1980

Prenatal diagnosis of a de novo non-fluorescent Y chromosome.

We report a case with non-mosaic Yq-, missing the fluorescent segment, and detected as a fetus studied for advanced maternal age. The father had a Y chromosome of average size and paternity was established wih a plausibility of 97.7% by HLA and erythrocyte antigen typing. The child had a normal male antigen typing. The child had a normal male phenotype at delivery and developmental milestones were normal through the first year of life. The Yq- showed no mitotic instability since it was retained in foreskin culture for its in vitro lifetime of 60 population doublings.

Adult↗
PubMed1980

Sleep apnea syndrome: correction with surgical advancement of the mandible.

Mandibular retrognathism is occasionally associated with sleep apnea syndrome. Most cases of this disorder have, until now, been treated with permanent tracheotomies. One patient with this syndrome was treated with surgical advancement of the mandible with bilateral C osteotomies and iliac corticocancellous grafts. Complete reversal of the sleep apnea symptoms and return of the sleep EEG to normal resulted after surgery. Although further study needs to be done, mandibular advancement would appear to be a preferable alterantive to tracheotomy for such patients.

Adult↗
PubMed1980

Multinucleate cells in cultures of human amniotic fluid form by fusion.

The major class of cells subcultured from human amniotic fluid retains properties of trophoblast. The objective of this study was to determine whether the multinucleate cells appearing in these cultures form by fusion, as is true for syncytiotrophoblast. Culture methodology involved subdivision of one flask into two, one of which was labeled with 3H-thymidine and the other with 14C-thymidine. Aliquots of each labeled culture were mixed together and allowed to grow. Autoradiographic study revealed binucleate cells containing one nucleus labeled with 3H and the other with 14C. This result indicates that fusion is one means by which binucleate cells form. The distribution of labeled and unlabeled nuclei in 217 binucleate cells obtained in two experiments was then determined. The distribution conformed to that predicted from the assumption that fusion was random and the only way for binucleate cells to form. We conclude that the binucleate cells appearing in cultures of human amniotic fluid form by fusion, as do the multinucleate cells in trophoblast. Our results suggest further that fusion is the sole means by which binucleate cells arise.

Amniotic Fluid↗
PubMed1979

Differentiation in human amniotic fluid cell cultures: chorionic gonadotropin production.

Two of the distinguishable cell classes subcultured from human amniotic fluid were examined for their capability to produce human chorionic gonadotropin (hCG) as determined by radioimmunoassay. The class that predominates in most cultures used for prenatal genetic diagnosis, previously termed AF (for amniotic fluid), secretes hCG into the culture medium. Dermal fibroblasts do not, nor does another type of cultured cell from amniotic fluid, previously termed F because of a resemblance to fibroblasts. Primary AF cultures produce more hCG than do subcultures. Evidence that this hormone is intact hCG is provided by its immunoreactivity with antisera raised against the beta-subunit and against the intact molecule of hCG. Furthermore, a dose-response curve for hormone in culture medium is parallel to that of highly purified intact hCG. It is postulated that AF cultures are derived from fetal membranes and retain properties of trophoblast.

Amniotic Fluid↗
PubMed1978

Prevalence of growth hormone deficiency in children with cleft lip or palate.

Two hundred children 7 to 14 years of age with isolated cleft defects of the lip, palate, or both were surveyed for stature. Twelve percent were less than the third percentile in height and were designated "short." All of the short children received an endocrine evaluation. Endogenous growth hormone was examined after two days' pretreatment with stilbesteral. Four of the 25 short children with CLP had total, and four had partial, GH deficiency. Three of the GH-deficient patients were also deficient in ACTH or TSH. In contrast, in a series of 75 short (less than third percentile) children 7 to 14 years of age without cleft defect or other apparent congenital abnormality, only two had total and two had partial GH deficiency. The data suggest that children with isolated CLP have short stature about four times more often, and GH-deficiency about 40 times more often, than children without CLP. The increased prevalence of GH-deficiency may stem from the embryologic relation of adenohypophysis and oral ectoderm.

Adolescent↗
PubMed1978

Origin of cells in human amniotic fluid cultures: ultrastructural features.

Two classes of cells can be subcultured from human amniotic fluid (F and AF). Ultrastructural features of these cultrued cells were determined using scanning and transmission electron microscopy with particular attention to extracellular material. Results obtained from these two cell types are compared to one another and to cultured human dermal fïbroblasts. The F-type cultures have an abundance of extracellular type i collagen fïbers, identical with cultured human dermal fïbroblasts. No type I collagen fïbers are seen in cultures of AF cells. Instead, fïne fïlamentous material is admixed with amorphous material adjacent to cell membranes where epithelial basement membrane glycoprotein has been localized. By scanning electron microscopy parallel arrays of cells are present at confluency of F cultures, typical of cultured dermal fïbroblasts. AF cultures show a much looser growth pattern at confluency. On the basis of accumulated evidence, we believe that F-type cells arise from fïbrous connective tissue and are fïbroblasts, whereas AF cells, the predominant type in early cultures used for prenatal genetic diagnosis, arise from fetal membranes and retain features of trophoblast.

Amniotic Fluid↗