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Biomedical subjects

J C Daniel

Publications and source records attributed to J C Daniel.

At least 55 records · Page 3Linked to original sources
PubMed1985

[Value of surgical hysteroscopy in the treatment of myomas and intracavitary fibrous polyps. Evaluation of 26 operations].

Out of a total of 121 hysteroscopies carried out in this unit between December 1981 and June 1984, 26 were operative hysteroscopies. Each of these procedures consisted in removing intra-uterine structures (that could not be removed with a curette) under visual control. All cases had a normal sized or slightly enlarged uterus. There were 7 patients aged 41 years or younger and 19 older than 41. The endoscope used was the "bayonet" Wolf apparatus which is 7 mm in diameter and has two separate canals; one for insufflation and the other for introducing the 3 mm biopsy forceps. This small punch makes it possible to cut the implantation on uterine wall without needing coagulation. The tissue is then removed using a soft curette or a polyp forceps after the cervix has been further dilated. There was no case in which heavy bleeding occurred during or after the operation. Using this technique we were able to remove 18 fibroid polyps, 13 submucous fibroids (8 smaller than 2 cm in diameter and 5 between 2 and 4 cm), 3 old retained portions of placenta; removal was complete in 21 cases and only partial in 5 cases. Out of these 2 had to have hysterectomy. On the other hand abdominal myomectomy or hysterectomy could be avoided in 11 cases. This series shows how often fibrous polyps and small sub-mucous fibroids can be removed under hysteroscopic control when using this kind of apparatus and a relatively simple technique.

Adult↗
PubMed1984

Synthesis of cartilage matrix by mammalian chondrocytes in vitro. III. Effects of ascorbate.

Chondrocytes isolated from bovine articular cartilage were plated at high density and grown in the presence or absence of ascorbate. Collagen and proteoglycans, the major matrix macromolecules synthesized by these cells, were isolated at times during the course of the culture period and characterized. In both control and ascorbate-treated cultures, type II collagen and cartilage proteoglycans accumulated in the cell-associated matrix. Control cells secreted proteoglycans and type II collagen into the medium, whereas with time in culture, ascorbate-treated cells secreted an increasing proportion of types I and III collagens into the medium. The ascorbate-treated cells did not incorporate type I collagen into the cell-associated matrix, but continued to accumulate type II collagen in this compartment. Upon removal of ascorbate, the cells ceased to synthesize type I collagen. Morphological examination of ascorbate-treated and control chondrocyte culture revealed that both collagen and proteoglycans were deposited into the extracellular matrix. The ascorbate-treated cells accumulated a more extensive matrix that was rich in collagen fibrils and ruthenium red-positive proteoglycans. This study demonstrated that although ascorbate facilitates the formation of an extracellular matrix in chondrocyte cultures, it can also cause a reversible alteration in the phenotypic expression of those cells in vitro.

Animals↗
PubMed1984

The effect of accelerated lactation on fetal maintenance in the rat.

Rats mated post partum were permitted to nurse 2 pups until day 9, at which time laparotomy was performed and the number of implantation sites counted. Control animals were left to nurse 2 pups or none, while lactation was then accelerated in 4 other groups by the addition of more pups to totals of 3, 5, 7 or 9. On day 19 the mothers were killed and the fetuses counted, weighed and checked for normality. With increased lactational demand the proportion of fetuses maintained decreased. Total fetal weight was decreased significantly only when 7 or more pups were being nursed. Individual fetal weights and normalcy were not affected by accelerated lactation.

Animals↗
PubMed1984

Prolactin as a factor in the uterine response to progesterone in rabbits.

The direct effect of prolactin on uteroglobin production and on uterine endometrial oestrogen and progesterone receptor concentrations was tested by using ovariectomized rabbits (at least 12 weeks) treated with prolactin; prolactin + progesterone; prolactin + oestradiol + progesterone; oestradiol + progesterone; or progesterone alone. Prolactin treatment produced a significant (P less than 0.05) increase in the concentration of cytosolic oestrogen and progesterone receptors, restoring the concentrations to values found at oestrus. However, the concentration of nuclear receptors remained low. In the remaining treatment categories there was no significant (P greater than 0.05) increase in the concentration of oestrogen and progesterone receptors compared with those in ovariectomized controls. However, the sequential treatment of ovariectomized animals with prolactin + progesterone stimulated uteroglobin production to a concentration equal to that found in intact rabbits on the 5th day of pregnancy. This was not achieved by prolactin or progesterone alone or with oestradiol. These results suggest that prolactin acts as an essential factor in the rabbit uterine response to progesterone, perhaps by the modulation of progesterone receptor activity.

Animals↗
PubMed1983

The effect of ascorbate on embryonic chick sternal chondrocytes cultured in agarose.

Primary cultures of embryonic chick sternal chondrocytes were embedded in a three-dimensional matrix of 1% solid agarose which was overlaid with nutrient media. The chondrocytes divided and formed nests of spherically shaped cells which were surrounded by an extensive extracellular matrix containing high molecular weight proteoglycans. Using light and electron microscopy, condensation of proteoglycan was observed pericellularly, often forming septa between cells of a nest, and as part of the outer boundary of the cell nest. No cross-striated collagen fibers were observed in the extracellular matrix although proteoglycan appeared to decorate a network of fine strands. Upon the addition of ascorbate to the nutrient media high molecular weight proteoglycans were synthesized, but there was a marked decrease in the synthesis of proteoglycans after a 10 day exposure to ascorbate. Morphologically, the decrease in proteoglycan synthesis was manifested in the discontinuous arrangement of the pericellular matrix as well as the diffuse form of the cell-nest boundary. Both of these structures were clearly defined in control cultures and were enriched in proteoglycan as demonstrated by ruthenium red staining. This study demonstrates that embryonic chondrocytes remain differentiated when cultured in solid agarose for a period of up to 15 days. They continue to synthesize their tissue specific macromolecules and are phenotypically stable when exposed to ascorbate for extended periods of time.

Animals↗
PubMed1983

Effect of ovarian transplantation to the uterus ("Estes operation") on reproduction in the rabbit.

The effectiveness of the "Estes operation," which was developed to correct fertility problems in humans suffering from tubal incompetence, was studied using rabbits. The ovaries of mature does were surgically transplanted into their uteri and the effects of this altered state on reproduction, host tissue and graft tissue were appraised. Animals with transplanted ovaries showed normal breeding behavior, but the only pregnancies resulted when does that had received heterotransplanted ovaries also retained their own ovaries in situ . Young produced in those pregnancies were shown to have originated from ova ovulated from the host's normal ovaries. Transplanted ovaries disappeared from the uterus, either by resorption or expulsion, within eight weeks if they were separated from their pedicles but were retained if left attached to their pedicles. Presumably the difference reflects the state of vascularization. Scar tissue developed at the junction of ovary and uterus, and the endometrial epithelium became continuous with the germinal epithelium of the ovary. The uteri receiving pedicled ovaries retained their normal size. Those of ovariectomized does were about half the weight of normal uteri and those of ovariectomized does receiving unpedicled ovaries atrophied to a size about half those of the ovariectomized does. When intact does received heterotransplanted ovaries in their uteri, those uteri hypertrophied to approximately twice the size of normal uteri. The effects of transplanting ovaries to the uterine lumen, as reported here, could explain the poor pregnancy success rate in humans and the complete failure to achieve pregnancies in any other mammalian species by use of the "Estes operation."

Journal Article↗
PubMed1983

Plasma progesterone concentrations in pregnant and non-pregnant black bears (Ursus americanus).

Plasma levels of progesterone were determined from serial samples taken from 2 black bears over 3 consecutive fall periods. Each animal was pregnant during the 1st and 3rd years. Variations in progesterone levels were seen between animals and within each animal between pregnancies. Average baseline levels during the mid-to-late preimplantation period were 5.0-12.5 ng/ml and increased 2-3 fold at the approximate time of implantation. Values during non-pregnancy were detectable but much lower (0.6-2.5 ng/ml). The observed pattern of progesterone secretion in this species appears consistent with that reported for other species exhibiting obligate delayed implantation.

Animals↗
PubMed1982

Synthesis of cartilage matrix by mammalian chondrocytes in vitro. II. Maintenance of collagen and proteoglycan phenotype.

The in vitro phenotype of bovine articular chondrocytes is described. Chondrocytes plated at high density in roller-bottle and dish cultures were maintained in vitro. The major matrix macromolecules, collagen and proteoglycan, synthesized by these cells were characterized during the course of the culture period. The chondrocytes synthesized mainly Type II collagen, which was found predominantly in the cell-associated matrix. The media contained a mixture of Type II and Type III collagens. Type I collagen was detectable in neither the medium nor the cell-associated matrix. The proteoglycan monomers found in media and cell-associated matrix had the same hydrodynamic sizes as monomers synthesized by cartilage slices or those extracted from adult articular cartilage. The majority of proteoglycans synthesized by the cells were found in high molecular weight aggregates which were readily recovered from the media and were extractable from cell-associated matrix with low ionic strength buffers. The results demonstrate the long-term in vitro phenotypic stability of the bovine articular chondrocytes. The advantages of the in vitro system as a model for studying the effects of external agents, such as drugs and vitamins, are discussed.

Animals↗
PubMed1981

Delayed implantation in the northern fur seal (Callorhinus ursinus) and other pinnipeds.

Delayed implantation is an obligate part of the reproductive cycle of many (possibly all) pinniped species, the duration of delay ranging from 2 to 4 months depending on the length of gestation. Blastocyst reactivation and implantation in the northern fur seal occur during decreasing photoperiods, and are preceded by increase in the circulating concentrations of oestradiol-17 beta and progesterone. However, neither experimental shortening of photoperiod, nor injections of oestradiol-17 beta or progesterone (or both) induced reactivation. Furthermore, these treatments had no effect on the composition or quantity of proteins in uterine flushings, examined by gel filtration (though changes are associated with spontaneous implantation). All treatments involving capture and caging of seals caused an increase in blastocyst mitotic activity (though not expansion), and it is suggested that this represents a response to stress. Experiments in which fur seal or rabbit blastocysts were cultured in vitro failed to identify a growth promoting substance whose absence from uterine fluid may account for the dormancy of blastocysts during diapause; however, these experiments did demonstrate the presence of an inhibitor or rabbit blastocyst growth in fur seal serum. It is suggested that an unidentified compound regulated by the ovary is involved in stimulating the increased uterine proliferation and secretion which are necessary for blastocyst reactivation.

Animals↗
PubMed1980

Regeneration of rabbit ear tissue.

Holes punched in the ears of rabbits are repaired by regeneration of new tissues from blastemas found on the periphery of the wounds. The proportion whch successfully regenerated was greater in males than in females (75% vs 20%), in pregnancy than during etrus or lactation (75% vs 25%), and in ovariectomized does given testosterone than in those given oil carrier alone (88% vs 50%), but the speed of closure did not differ in these groups. The steroid hormone influence postulated by other workers is confirmed. Closure was faster in younger animals and for second holes punched on the same site where earlier holes had been repaired, in both cases, by shortening of the initial seven to ten day delay period seen for primary holes in adult ears. The cartilage layer was also thicker after regeneration from secondary punches and the success rate greater (67% vs 29%). These observations suggest a "priming" effect on the tissue from the primary punch. Ear holes in the area proximal to the head were repaired faster and with more success (78% vs 12%) than those punched distally. The relative thickness of the cartilage layer may be the critical factor. Tissues did not regenerate from semicircular layer may be the critical factor. Tissues did not regenerate from semicircular wounds made on the edge of the pinna. Hair grown on regenerated ear skin reestablished the original color pattern. Skin regenerating for hles punched where skin from the back had been transplanted to ears had the characteristics of back skin, but no regeneration was detectable from transplanted toe tissue. Skin from other locations can regenerate in the environment provided by the ear but more complex tissue structures put into the same locatin apparently cannot. Skin cells involved in regeneration originate from the tissues bounding the wound.

Age Factors↗
PubMed1978

Amino acid sequence of a progesterone-binding protein.

The amino acid sequence of blastokinin, also called uteroglobin, has been determined by a combined study of both the intact native molecule and the peptide fragments resulting from tryptic and chymotryptic digestions. Sequence analyses performed by automated methods and by sequential digestion with leucine aminopeptidase and carboxypeptidase Y demonstrate that blastokinin is a dimer of identical 69-amino acid subunits held together in parallel orientation by two disulfide bridges at positions 3 and 68. The polypeptide chains are further characterized by the absence of tryptophan residues and by single residues of histidine and tyrosine at positions 8 and 21, respectively. Six of eight amino acids, positions 17--24, near the progesterone binding site of blastokinin contain a hydroxyl group. Knowledge of the chemistry of this receptor site should allow better perspectives of the chemistry of molecules in normal tissues that are dependent on progesterone for growth and development, as well as compounds that could act as cancer antagonists for endocrine therapy of hormone-dependent tumors.

Amino Acid Sequence↗
PubMed1978

Crystalline inclusion bodies in rabbit embryos.

Crystalline inclusion bodies (CIB) may be found as prominent ultrastructural components of the trophoblast cells of rabbit blastocysts and of progestational uterine endometrium. In the work reported here we have sought to describe developmental steps in crystal formation, to correlate these events with embryonic age and to determine if the uterus is essential (either as a source or an environment) for crystal formation in the embryo. CIB, which are of a size and periodicity to make them appear to be clusters or packages of microtubules, are first detectable in embryos 4 days 6 h post coitum and by 41/2 days are well established in significant numbers. Another structural component, granular vesicles, may be seen in embryos as early as 21/2 days post coitum, and decrease in number during the same time the CIB are increasing. We believe that the CIB originate from the pre-existing granular vesicles and present electron micrograph evidence of crystal formation progressing from such vesicles. CIB formation does not occur in 41/2- to 5-day-old embryos which have been locked in the oviduct by a suture around the utero-tubal junction. However, when such tube-locked embryos are transplanted into the uterus, they develop crystals within 36 h thereafter. We conclude that the uterus is essential for CIB formation to occur in the rabbit embryo.

Animals↗
PubMed1977

Comparison of in vivo and in vitro ribosomal RNA synthesis in nucleolar mutants of Xenopus laevis.

Cells of embryos carrying a lethal nucleolar mutation have been maintained in vitro for extended periods of time. Normally these mutants live only 9 to 12 days after fertilization but their cells in culture will survive for more than 3 months. The extent of ribosomal RNA (rRNA) synthesis was determined in primary cultures prepared from normal embryos and nucleolar mutants having different numbers of ribosomal RNA genes. We found that the accumulation of radioactivity into rRNA for normal and mutant embryos was similar in vivo and in vitro. In primary cultures of normal embryos which have two nucleoli per cell and mutant embryos which have only one nucleolus per cell, the incorporation of radioactivity into rRNA was similar even though the normal cells have twice as many rRNA genes. Thus the mechanism which regulates dosage compensation of the rRNA genes operates both in vivo and in vitro.

Animals↗
PubMed1977

Induction of uterine protein synthesis by synthetic progestins.

The capacity of artificial progestins, each possessing a C-19 methyl group, to stimulate protein synthesis in the uteri of castrated New Zealand White rabbits was studied in an attempt to screen for this type of progestational activity. It is apparent that modifications of the 4-pregnen-3,20-dione molecule not only alter total protein production, but also effect changes in the synthesis of the uterine protein, blastokinin, in comparison with the effect of unaltered progesterone. This indicates that altering the molecular configuration of progesterone offers contraceptive potential through its ability to influence the preimplantation uterine environment.

Animals↗
PubMed1976

Gallium-67 distribution in pregnant mammals.

Studies on the distribution of 67Ga in pregnant rabbits showed a marked concentration of the isotope in uterine tissue and flushings of 5-day pregnant rabbits 24 hours after isotope injection. The isotope no longer localized throughout the uterine tissues and flushings on injection of 7- to 8-day pregnant rabbits but was specifically associated with the blastocysts and sites of implantation. As the gestation time progressed 67Ga increasingly concentrated in placental and mammary tissue while the concentration in serum and thymus tissue decreased. The marked concentration in placental tissue was readily discernible on total-body scans of pregnant rabbits. Column chromatography of uterine washings and placental extracts from pregnant rabbits and thymus extracts from estrous rabbits showed most of the isotope associated with moieties greater than or equal to 200,000 MW whereas the isotope in "milk" and extracts of mammary tissue was bound to components of 25,000-35,000 MW. Extracts of thymus from pregnant rats showed a marked, selective loss of 67Ga binding in two peaks of approximately 50,000 and 120,000 MW compared to the chromatographic profile of extracts from normal rat thymus.

Animals↗