Search PubMed⌕ Search

Biomedical subjects

J Richards

Publications and source records attributed to J Richards.

At least 181 records · Page 10Linked to original sources
PubMed1981

Responses of synchronized HeLa cells to the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate as evaluated by flow cytometry.

A flow cytometric study was carried out on the effects of tumor-promoting 12-O-tetradecanoylphorbol-13-acetate (TPA; 10(-8) M) on HeLa cells synchronized by amethopterin for DNA synthesis. Cells treated with TPA at the time of release from the amethopterin block showed a delayed passage through S phase and partially through G2 in their immediate life span as measured 24 hr after release. This late G2 delay was not observed when TPA was added to cells during late S or G2 phase. In this case, however, a direct inhibition of cells in G2 became evident as observed about 15 hr after release from block. None of these effects was caused by the nonpromoting 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate (10(-6) M). These data support observations obtained with asynchronous cultures. The TPA effects resemble those reported after X-irradiation of cell cultures.

Cell Cycle↗
PubMed1980

The classification, investigation and treatment of the anaemic patient.

Anaemia is one of the commonest symptoms reported to medical practitioners by their patients. A combined morphological and functional approach to classification is preferred, but the crucial point is the need to establish the cause of the symptom before selecting any form of therapy. Treatment before making an accurate diagnosis, especially the use of haematinics other than those specifically needed, may be dangerous and cannot be too strongly deprecated.

Anemia↗
PubMed1980

Primary culture of mouse mammary tumor epithelial cells embedded in collagen gels.

Mammary tumor epithelial cells from BALB/cfC3H mice were dispersely embedded inside the collagen gels in Ham's F-12 medium containing horse serum. A sustained cell growth leading to a 5- to 10-fold increase in cell number over initial level was observed in less than 2 weeks. The extent of this growth was found to be dependent on serum concentration. However, addition of various protein and steroid hormones, both singly and in combination, to low-serum-containing medium failed to achieve a comparable level of growth to that promoted by higher serum concentration. Mammary tumor cells can now be consistently propagated in primary culture.

Adrenal Cortex Hormones↗
PubMed1980

Sustained growth in primary culture of normal mammary epithelial cells embedded in collagen gels.

Normal mammary epithelial cells from BALB/cfC3H midpregnant mice were freed from stromal cell types by Percoll density gradient centrifugation after collagenase digestion and were then embedded within collagen gels. Sustained growth leading to an increase in cell number was accomplished in response to cholera toxin and high concentrations of horse serum. The extent of growth was found to be dependent on the horse serum concentration, the maximum growth being attained at 50%. A serum concentration of 12.5% horse serum and 2.5% fetal calf serum, along with cholera toxin at 0.01 mug/ml, allowed maintenance but failed to cause any significant increase in cell number during the experimental period of 2 weeks. This same maintenance medium was used to determine the effects of various exogenously added steroids, protein hormones, and organ extracts on the proliferation of mammary epithelial cells in culture. Hormones failed to elicit any proliferative response, but extracts of kidney, brain, uterus, and spleen produced proliferative responses equal to or greater than the response obtained with 50% horse serum and cholera toxin. Kidney extracts prepared from midpregnant mice, virgin mice, and virgin mice given pituitary isografts all showed comparable activities, suggesting that the concentration of stimulatory factor(s) was not influenced by the hormonal status of the donor. Normal mammary epithelial cells that had undergone a 10- to 15-fold increase in cell number over initial values during 2-3 weeks in culture were passaged to secondary gel cultures. Outgrowth similar to those seen in primary culture were seen again in secondary culture. The present system provides a method for sustaining growth in culture of primary mammary epithelial cells from normal tissues.

Animals↗
PubMed1980

Effects of a zinc citrate mouthwash on dental plaque and salivary bacteria.

A double-blind crossover trial was carried out to assess the effect of zinc citrate on plaque accumulation in vivo and to measure total salivary aerobes and anaerobes both during the trial and throughout the day following a single rinse. When compared to the placebo, zinc citrate significantly reduced the plaque accumulation in the subjects. However, the mean reduction was small and of questionable clinical importance. A progressive increase in plaque was observed throughout both active and placebo 7-day rinsing periods. There was no significant reduction in salivary bacterial counts either during the crossover study or during the day following a single rinse with zinc citrate.

Bacteria↗
PubMed1980

Tumor promoter TPA mimics irradiation effects on the cell cycle of HeLa cells.

When asynchronous and synchronous HeLa cells were incubated with small doses (10(-7) M) of tumor promoter 12 O-tetradecanoylphorbol-13-acetate (TPA), a variety of transient alterations in the replication cycle were detected within 24 hours by the use of independent methods. Especially, a delayed passage through the S phase and influences on the G2 phase resemble x-ray irradiation effects on cell cultures. None of these alterations was observed with the hyperplasiogenic but nonpromoting 4-O-methyl-TPA.

Cell Cycle↗
PubMed1980

Prospective study of fetal heart rate and rhythm patterns.

The fetal heart beat, detected by ultrasound, was recorded for five minutes from 934 antenatal women--266 at 30 to 35 weeks' gestation and 718 at 36 to 41 weeks. Episodes of bradycardia < 100/minute ranging from 5-30 seconds' duration occurred in 3 (1.1%) of the former and in 9 (1.3%) of the latter group. Tachycardia > 180/minute ranging from 30-90 seconds' duration occurred in 1 (0.4%) of the former and in 4 (0.6%) of the latter. Premature beats were not detected between 30 and 35 weeks, but occurred in 12 (1.7%) of 720 at 36 to 41 weeks' gestation. 50 subjects were monitored at both 30 and 35 weeks and 36 to 41 weeks' gestation and in one woman premature beats were present in the latter but not in the former recording. The incidence (1.7% of premature beats in the fetus at 36 to 41 weeks' gestation was similar to that in the healthy neonate (0.8%). Recordings of arrhythmias or rates outside the range 100-180/minute were replayed through a standard antepartum fetal heart rate monitor. The monitor failed to detect premature beats, 2 to 4 episodes of tachycardia > 180/minute, and 9 of 12 episodes of bradycardia < 100/minute, stressing its unreliability for detecting rapidly changing rates.

Arrhythmias, Cardiac↗
PubMed1980

Study of cardiac rhythm in healthy newborn infants.

Twenty-four-hour electrocardiograms were recorded in the first 10 days of life on 134 healthy full-term infants with birthweights greater than 2.5 kg. The highest heart rate a minute, measured over nine beats, was 175 +/- 19 (SD). The lowest rates, measured over three, five, and nine beats were 82 +/- 12, 87 +/- 12, and 93 +/- 12, respectively. At their lowest rates 109 infants had sinus bradycardia and 25 had junctional escape rhythms. Thirty-three infants showed changes in P wave configuration with or without pronounced variation in PR interval. Atrial premature beats were present in 19 infants but only one had more than 12 per hour. In a randomly selected subgroup of 71 infants sinus pauses were found in 51 (72%). Five (7%) had electrocardiographic patterns and rhythm disturbances that could not be differentiated from those previously described as complete sinuatrial exit block or sinus arrest, eight (11%) had patterns indistinguishable from 2:1 sinuatrial block, and 23 (32%) had pattern indistinguishable from sinuatrial Wenckebach block. This study shows that normal infants have variations in heart rate and rhythm hitherto considered to be abnormal.

Electrocardiography↗
PubMed1980

Growth factor- and cyclic nucleotide-induced proliferation of normal and malignant mammary epithelial cells in primary culture.

Sustained growth of normal mouse mammary epithelial cells in primary culture, leading to an increase in cell number, in response to growth factors [epidermal growth factor (EGF) and fibroblast growth factor (FGF)] or cholera toxin has been achieved by embedding the cells inside collagen cells. Inclusion of agents known to increase the level of cellular cAMP have been found to be favorable for mammary epithelial cell proliferation. Cholera toxin is by far the best of all of the agents tested (prostaglandins E1 and E2, isoproterenol, theophylline, and dibutyryl cAMP). When growth factors (EGF or FGF) are added with cholera toxin, a synergistic effect resulting in a response much greater than with either of them alone is seen. This synergism was best seen in normal mammary epithelial cells from nonpregnant mice. The extent of this synergistic effect was found to be less in normal cells from pregnant mice, suggesting that these cells may be less responsive to EGF during pregnancy. Tumor cells were found to be rather inconsistent in their responses to EGF and cholera toxin, ranging from a minimal response, similar to that of normal cells from pregnant animals, to a maximal response, similar to that of normal cells from nonpregnant animals.

Animals↗
PubMed1980

Primary culture of human mammary epithelial cells embedded in collagen gels.

Human mammary epithelial cells were dissociatd from mastectomy tissues. The contaminating fibroblasts were removed by the use of Percoll density-gradient centrifugation, which utilizes the difference in buoyant densities between epithelial cells and fibroblasts. A preparation highly enriched for mammary epithelial cells ws then embedded in collagen gel and cultured in Ham's F12 medium containing 12.5% horse serum, 2.5% fetal calf serum, 0.1 microgram cholera toxin/ml, an extract prepared from human male urine (L microgram protein/ml), and a hormone combination of 10 microgram insulin/ml, 10 microgram human placental lactogen/ml, 1 microgram aldosterone/ml, and 0.5 microgram hydrocortisone/ml. Sustained growth leading to an increase of tenfold to thirtyfold in cell number over the initial value was accomplished in primary culture, and this growth was maintained even after passage to secondary culture. Deletion of either the urine extract or the hormone combination resulted in less than optimal growth. Subsequent studies showed that hydrocortisone alone could replace the hormone combination. In addition, urine extract could be replaced by extracts prepared from human kidneys or brains. The collagen gel system provies a reproducible and consistent method for sustained three-dimensional growth of mammary epithelial cells from human breast tissue in primary as well as passaged cultures.

Aldosterone↗
PubMed1979

Sequence of the cloned gene for the constant region of murine gamma 2b immunoglobulin heavy chain.

The complete nucleotide sequence of the gamma 2b constant region gene cloned from BALB/c liver DNA is reported. The sequence of approximately 1870 base pairs includes the 5' flanking, 3' untranslated, and 3' flanking regions and three introns. The C gamma 2b coding region is divided by these introns into four segments corresponding to the homology domains and hinge region of the protein. The introns separating the hinge from the CH2 domain and the CH2 from the CH3 domain are small (106 and 119 base pairs). A larger intervening sequence of 314 base pairs separates the CH1 and hinge regions. The stretch of DNA comprising this large intron plus the hinge shows a strong homology with the other CH domains.

Animals↗
PubMed1979

Speech, language and hearing disorders in a adult penal institution.

It has been speculated that the prevalence of communicative disorders among prison inmates is considerably higher than that found in the general population, but research regarding inmate speech and hearing disorders is limited. This study investigated the nature and extent of communicative disorders in an inmate population of a medium-security penal institution in southeastern Virginia. The results of the screening indicated a slightly lower prevalence of stuttering, higher prevalences of articulation, voice, and hearing disorders, and more deficient receptive vocabulary skills than found in the general population. Some dialectal variations among black inmates are noted and the possible influence of linguistic-cultural interference on the results is discussed.

Adolescent↗
PubMed1979

Sustained growth and three-dimensional organization of primary mammary tumor epithelial cells embedded in collagen gels.

We have developed a method for embedding cells within a collagen matrix which allows sustained growth of mouse mammary tumor epithelial cells in primary culture. A characteristic and reproducible pattern of organization and growth occurs: the cells rearrange themselves and produce duct-like structures extending into the matrix, resulting in a three-dimensional outgrowth. Autoradiography showed continuous [3H]thymidine incorporation during 8 weeks in culture. An increase in DNA content of the cultured cells as a function of time was observed. Mouse mammary tumor cells cultured in the conventional monolayer system failed to show any significant increase in cell number during a culture period of 6 weeks. In addition, in such monolayer systems, cells progressively became detached from the dishes in long-term culture. The mammary epithelial cell origin of the collagen gel cell outgrowths was shown by electron microscopic demonstration of polarized cells containing tight junctions and budding mammary tumor virus particles. In addition, in vivo transplantation of collagen gel outgrowths resulted in the development of mammary adenocarcinoma histologically similar to the donor tumor. Cellular outgrowth patterns resembling those from tumor cells were also seen in similar collagen gel cultures of normal mammary cells from mouse and human and of hyperplastic alveolar nodule cells from mouse. The significance and usefulness of this system in comparison to the conventional monolayer system are discussed.

Animals↗