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Biomedical subjects

D J Hill

Publications and source records attributed to D J Hill.

At least 19 recordsLinked to original sources
PubMed1992

Laparoscopically assisted hysterectomy.

OBJECTIVE: To determine the feasibility and effectiveness of laparoscopically assisted hysterectomy. DESIGN: A prospective study of the planned surgical procedure was carried out by two teams, each with two gynaecologists, who were experienced in operative laparoscopy. SETTING: The operations were carried out in a private hospital, where advanced operative laparoscopy equipment was available. PATIENTS: Seventeen patients were selected for the procedure, all of whom required hysterectomy for symptoms of pain or menorrhagia in association with uterine or other pelvic disease. Patients with carcinoma or uterine enlargement beyond 12 cm were excluded. PROCEDURE: Laparoscopically assisted hysterectomy was carried out by means of a video monitor, uterine manipulation by vaginal instrumentation, three or four abdominal punctures of less than 1 cm, and bipolar diathermy to secure vascular pedicles. The uterus was removed from the vagina by cutting vaginal skin and the cardinal ligaments. RESULTS: The operating time was 90-220 min, the blood loss was 30-200 mL, and the hospital stay lasted two to five days and convalescence two to four weeks. No serious complications occurred. CONCLUSIONS: Laparoscopically assisted hysterectomy may be valuable when adnexal or uterine abnormalities are present and vaginal hysterectomy is either contraindicated or more difficult. The procedure requires special equipment and may only be carried out by experienced gynaecological operative laparoscopists. Its acceptance will depend upon reducing the operating time to less than 90 min. It has the advantage of reducing the duration of hospital stay and the duration of convalescence when compared with abdominal hysterectomy.

Adult↗
PubMed1992

Expression of insulin-like growth factors (IGFs) and their binding proteins (IGF BPs) during pancreatic development in rat, and modulation of IGF actions on rat islet DNA synthesis by IGF BPs.

Growth of pancreatic beta-cells is an essential feature of development in order to maintain insulin availability. While glucose has been shown to increase beta-cell DNA synthetic rate in cultures of isolated islets of Langerhans, there is also evidence for a local control of beta-cell growth involving insulin-like growth factors (IGFs). IGF I and II and their specific binding proteins (IGF BPs) are expressed within the developing rat pancreas, and released by isolated fetal rat islets of Langerhans. Glucose-induced beta-cell growth is not mediated by IGF-I, since IGF release does not alter in response to changes in glucose availability. In contrast, IGF BP release is positively associated with glucose concentrations over the physiological range and is therefore a candidate. Exogenous hIGF BP1 or bIGF BP2 synergistically interacted with hIGF I or II to increase DNA synthesis within isolated fetal rat islets. These results suggest a role for IGF BPs in the regulation of beta-cell growth. They may act independently or by modulation of IGF bioavailability during pancreatic development.

Animals↗
PubMed1992

Peptide growth factors and their interactions during chondrogenesis.

Peptide growth factors have been implicated in three aspects of cartilage growth and metabolism; the induction of mesoderm and differentiation of a cartilaginous skeleton in the early embryo, the growth and differentiation of chondrocytes within the epiphyseal growth plates leading to endochondral calcification, and the processes of articular cartilage damage and repair. Three peptide growth factor classes have been strongly implicated in these processes, the fibroblast growth factor family (FGF), the insulin-like growth factors (IGFs) including insulin, and transforming growth factor-beta (TGF-beta) and related molecules. Each of these peptide groups are expressed in the early embryo. Basic FGF, TGF-beta and the related activin have been shown to induce the appearance of mesoderm from primitive neuroectoderm. TGF-beta and related bone morphometric proteins can induce the differentiation of cartilage from primitive mesenchyme, and together with basic FGF and IGFs promote cartilage growth. Each class of growth factor is expressed within the epiphyseal growth plate where their autocrine/paracrine interactions regulate the rate of chondrocyte proliferation, matrix protein synthesis and terminal differentiation and mineralization. Basic FGF may prove useful in articular cartilage repair, while basic FGF, IGFs and TGF-beta are among a number of growth factors and cytokines that have been implicated in cartilage disease.

Animals↗
PubMed1992

Charting infant distress: an aid to defining colic.

The value of a 24-hour distress diary, previously validated against a voice-activated audiotape record, was investigated in 30 infants with colic and 30 control infants. The infants with colic had significantly more distress behavior (300.0 minutes vs 102.5 minutes; p < 0.001), although overlap of duration of distress was noted. On the basis of a clinical definition of colic--total distress lasting 180 minutes in a 24-hour period--the diary had a sensitivity of 77% and a specificity of 87%. The sensitivity of the chart was confirmed in a separate study of another 90 infants with colic.

Child Behavior↗
PubMed1992

Alcohol use, smoking habits and the Adult Eysenck Personality Questionnaire in adolescent Australian twins [corrected].

In 1988, questionnaires were received from 1,400 twin pairs (17% MZM, 23% MZF, 17% DZM, 19% DZF, 24% DZO) aged 11 to 18, registered with the Australian NHMRC Twin Registry. Twins reported independently on themselves and on the perceived behaviour of their parents, siblings and friends. For smoking and for drinking in the previous month, the prevalence was modelled as a logistic function of age, sex, perceived smoking or drinking behaviour of family and friends, and the Adult Eysenck Personality Questionnaire (AEPQ) scales. Strengths of association were: family behaviour, odds ratio (OR) < or = 2; Extraversion and Psychoticism, interquartile OR approximately 1.6; behaviour of friend, OR approximately 3 to 6. Twin associations were represented by odds ratios. For smoking they were 16 in MZ and 7 in DZ same-sex pairs, and 3 in DZO pairs. Although the former is consistent with genetic factors determining adolescent smoking behaviour, the reduced association in DZO pairs and strong association with smoking by friends argue to the contrary. For drinking, twin odds ratios were 11 in MZM, MZF and DZF pairs, and 4 in DZM and DZO pairs, consistent with genetic factors determining alcohol use in male but not female, adolescents. Twin odds ratios were not influenced by adjustment for the AEPQ scales; this does not support the hypothesis that genetic factors which determine personality also determine smoking or drinking behaviour during adolescence [corrected].

Adolescent↗
PubMed1992

Peptide growth factor interactions in embryonic and fetal growth.

Peptide growth factors are expressed by multiple tissues in the animal and human embryo and fetus. They undergo specific interactions which control the rate of cellular proliferation, tissue differentiation and the induction of specific morphogenic events such as mesoderm formation in the embryo. Biologic control may not only be exerted at the level of growth factor synthesis and receptor expression but by the sequestration and storage of growth factors by extracellular matrix molecules. In the case of insulin-like growth factors (IGFs), storage maybe mediated by attachment to specific IGF-binding proteins which may additionally modulate biological potency. Basic fibroblast growth factor (basic FGF) and transforming growth factor-beta (TGF beta) directly bind to glycosaminoglycan molecules. Release of growth factors from these stores may be by local proteolytic action. A sequential expression of basic FGF, IGF-II and TGF beta occurs in the ovine fetal epiphyseal growth plate as chondrocytes progress from a proliferative to a postmitotic, hypertrophic state. Cellular phenotype may be largely explained by the relative amounts of these autocrine growth factors within the growth plate.

Animals↗
PubMed1992

What is the role of growth hormone and related peptides in implantation and the development of the embryo and fetus.

The role of growth hormone (GH) and the related placental lactogens in implantation and subsequent embryonic and fetal development is an enigma. Firstly, these peptides are abundant in both the fetal and maternal circulation. The variant growth hormone (hGH-V) is expressed by the placental syncytiotrophoblast and is released into the maternal circulation. It is not detectable in fetal blood. Fetal pituitary (GH) is abundant but is not a primary stimulus to human fetal musculoskeletal growth, since hypopituitary newborn infants have near-normal birth size. However, pituitary hGH has been shown to stimulate pancreatic islet growth and insulin release in vitro, and to be a mitogen for fetal hepatocytes obtained in late first trimester. This selectivity of action is confirmed by the immunohistochemical localization of hGH receptor in the human fetal kidney, endocrine pancreas, liver, skin and brain during the first and second trimester, and their absence from the musculoskeletal system, gut and lung. High-affinity human placental lactogen (hPL) receptors are abundant in animal and human fetal tissues, and hPL can attain concentrations of 10 nM in the human fetal circulation. In vitro data strongly suggest anabolic and mitogenic actions for PL on fetal tissues, including amino acid transport, hepatic glycogenesis, protein synthesis, and stimulation of insulin-like growth factor and insulin release. The PL axis in the fetus is influenced by maternal nutrition. Despite these findings, definitive evidence is still lacking that PL contributes to fetal growth and development in utero.

Embryo Implantation↗
PubMed1992

Regulation of thyroid hormone synthesis in cultured ovine thyroid follicles.

Primary cultures of sheep thyroid follicles were used to study the regulatory control mechanisms of thyroid hormone production. When maintained under serum-free conditions in vitro these follicles exhibit hormone-dependent iodide transport, iodine organification, and physiological de novo thyroid hormone formation. In previous studies we have also shown that thyroid follicles condition their culture media with insulin-like growth factors (IGFs) and IGF-binding proteins which are of potential autocrine or paracrine significance in thyroid hormonogenesis. TSH (100 microU/ml) alone modestly stimulated iodine uptake and organification, which was further potentiated by pharmacological or physiological concentrations of insulin and by physiological concentrations of IGF-I or IGF-II. A combination of TSH and cortisol (10 nM) optimally stimulated iodine uptake and organification without additive or synergistic effects among combinations of cortisol with insulin or IGFs. Insulin, IGF-I, IGF-II, or cortisol alone were without effect on iodine uptake and organification. The effect of TSH was mimicked by forskolin or (Bu)2cAMP, and the synergistic effect of cortisol with TSH was duplicated in incubations of dexamethasone with TSH. In long term studies of the same experimental conditions, with 10(-6) M NaI added to the culture medium, an increase in radioimmunoassayable T4 and T3 in conditioned cell culture media and cell layer extracts was confirmed for all conditions, with the exception of physiological concentrations of insulin. IGF-I and IGF-II were equipotent in their stimulation of thyroid hormonogenesis in the presence of TSH. The effect of high concentrations of insulin may be explained by a combined action through insulin and type I IGF receptors. We have previously reported that the stimulation of iodine uptake and organification (de novo thyroid hormone formation here) by TSH and cortisol is inversely correlated with their inhibition of IGF-binding proteins released by the cells while IGF release is unchanged. Overall, these data suggest that the regulation of thyroid hormonogenesis involves the endocrine hormones TSH and cortisol, acting in synergy with locally produced IGFs.

Analysis of Variance↗
PubMed1992

Mitogenic action of gastrin-releasing polypeptide on isolated epiphyseal growth plate chondrocytes from the ovine fetus.

Gastrin-releasing polypeptide (GRP) has been implicated in the development of the human fetal lung. To determine whether GRP has a wider role in fetal development, its actions on DNA synthesis and cell replication by isolated epiphyseal growth plate chondrocytes obtained from ovine fetuses between 35 days gestation and near term (145 days) were examined. Chondrocytes were isolated using collagenase from the proximal tibia and cultured in monolayer. Synthesis of DNA was assessed from the incorporation of [3H]thymidine into previously growth-restricted cells after incubation in medium supplemented with GRP1-27 (40-1280 nM). Increase in cell number was assessed after incubation with test medium for 1 week. GRP caused a dose-dependent increase in both cell number and DNA synthetic rate compared to control incubations. Cell number was increased by 50% in the presence of a maximally effective 160 nM GRP and DNA synthesis by up to 800% utilizing chondrocytes obtained from animals of 75-80 days gestation. The mean (+/- SEM) half-maximal concentration of GRP for the stimulation of DNA synthesis was 97 +/- 12 nM (5 separate fetuses). Concentrations of GRP in excess of 160 nM caused a sharp reduction in both cell replication and DNA synthesis. To determine where within the cell cycle GRP exerted its mitogenic action, synchronized chondrocytes were transiently exposed to fetal bovine serum and cultured with GRP for increasing periods of time before pulse labeling with [3H]thymidine during S phase. GRP was as effective in stimulating DNA synthesis when present for the initial 4 h of G1 as when present for the entire G1 period. Since isolated fetal growth plate chondrocytes release insulin-like growth factor II (IGF II) and basic fibroblast growth factor (basic FGF) the possible mediation of GRP action by the release of these peptides or synergistic interactions were examined. Specific antibodies shown to negate the mitogenic actions of exogenous IGFs or basic FGF on chondrocytes did not alter GRP-stimulated DNA synthesis. The release of radioimmunoassayable IGF II by chondrocytes was not altered in the presence of GRP. Coincubation of GRP with submaximal concentrations of IGF I or basic FGF showed additive effects on DNA synthesis. When the actions of galanin were examined it was found to inhibit basal DNA synthesis by chondrocytes at a concentration of 167 nM. However, 66 nM or greater galanin was able to render 160 nM GRP inactive as a mitogen. These results suggest that GRP may potentially influence skeletal development in the ovine fetus and may interact with locally released peptide growth factors or other neuropeptides.

Analysis of Variance↗
PubMed1992

Prolonged hypoxia induced by the reduction of maternal uterine blood flow alters insulin-like growth factor-binding protein-1 (IGFBP-1) and IGFBP-2 gene expression in the ovine fetus.

Insulin-like growth factors (IGF-I and IGF-II) are potent mitogenic and differentiating peptides which are synthesized by many fetal tissues. In the circulation and tissue fluids, IGFs are bound to binding proteins (BPs) which not only function as carrier proteins, but also inhibit or modulate the biological actions of IGFs. We have previously shown that prolonged hypoxia in the ovine fetus induced by the reduction of maternal uterine blood flow for 24 h causes a reduction in the DNA synthesis rate in selected fetal tissues. To determine if this effect is due to alterations in the local synthesis of tissue IGFs and their binding proteins or to changes in systemic concentrations of IGFs and IGFBPs, we have investigated the abundance of mRNAs encoding IGFs and IGFBPs in selected tissues and changes in plasma IGFs and IGFBPs. Ovine fetuses (115-120 days gestation; n = 6) underwent 24 h of hypoxia by the reduction of maternal uterine blood flow (RUBF). Controls (n = 6) underwent the same surgical procedure without RUBF. Serial plasma samples were collected before, during, and after the experiment, and tissues were collected at the end of 24 h. Mean plasma IGF-I and IGF-II concentrations tended to be lower in hypoxic fetuses than in controls during the course of hypoxia, but these differences were not statistically significant. Tissue mRNA levels for IGF-I and IGF-II in lung, muscle, thymus, and kidney were similar in control and hypoxic fetuses after 24 h of hypoxia. The relative abundance of liver IGF-I and IGF-II mRNAs was lower in hypoxic fetuses, but only IGF-I mRNA levels were significantly different from the control values (P < 0.05). Compared to control fetuses, IGFBP-1 mRNA levels in the liver of hypoxic fetuses were increased 3- to 7-fold, and IGFBP-1 mRNA expression was induced in kidneys of some hypoxic fetuses (two of six). In addition, IGFBP-2 mRNA levels were decreased in the liver (50%) and kidney (30%) of hypoxic fetuses. The increase in liver IGFBP-1 mRNA abundance and the decrease in liver and kidney IGFBP-2 mRNA abundance were accompanied by an increase in IGFBP-1 levels and a decrease in IGFBP-2 levels in fetal plasma. No changes were observed in either plasma levels or tissue mRNA abundance for IGFBP-3. Analysis of the time course of changes in plasma revealed that the changes in IGFBP-1 and IGFBP-2 occurred within 4 h of hypoxia.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Localization of the growth hormone receptor, identified by immunocytochemistry, in second trimester human fetal tissues and in placenta throughout gestation.

Pituitary GH secretion appears largely unnecessary for the attainment of normal birth size in many species, including man. This is believed to be due to an immaturity and/or an absence of GH receptors in many fetal tissues. However, in vitro studies using late first trimester human fetal tissues have demonstrated mitogenic actions of GH on liver and stimulation of insulin biosynthesis in pancreas. To resolve this discrepancy, we have employed immunocytochemistry to identify the presence and distribution of GH receptors in various human fetal tissues. Fetuses of 14-16 weeks gestation were obtained after therapeutic abortion, tissues were fixed, and immunocytochemistry was performed using monoclonal antibodies against purified rat or rabbit GH receptor. The specificity of staining was confirmed by preabsorption of the antibodies with 1) adult rat liver membranes or 2) human fetal liver membranes, both of which possess specific GH-binding sites, or 3) human fetal skeletal muscle membranes, which do not specifically bind GH. Positive staining was seen in a subpopulation of liver parenchymal cells, in the ductal and endocrine tissue of pancreas, in the germinal layer of the epidermis and the deeper dermal layers of skin, and in the tubular epithelium of kidney. No immunopositive staining was seen in skeletal or cardiac muscle, epiphyseal growth plate, lung, intestine, or adrenal. Positive staining was present in the neuronal cell bodies of the cerebral cortex. GH receptor was also detectable as early as 8 weeks gestation in syncytial layers of the placenta and was maintained until term. Results demonstrate the presence of immunoreactive GH receptor/binding protein in some human fetal tissues early in development. In particular, these results would support a role for GH in the growth and function of liver and pancreas.

Extraembryonic Membranes↗
PubMed1992

Control of protein and matrix-molecule synthesis in isolated ovine fetal growth-plate chondrocytes by the interactions of basic fibroblast growth factor, insulin-like growth factors-I and -II, insulin and transforming growth factor-beta 1.

Chondrogenesis is thought to be controlled by interactions between circulating anabolic hormones and locally produced peptide growth factors, and involves ordered changes in matrix composition which ultimately allow endochondral calcification. We have used a model of isolated ovine fetal growth-plate chondrocytes to examine the actions and interactions of basic fibroblast growth factor (basic FGF), insulin-like growth factors-I and -II (IGF-I and -II), insulin and transforming growth factor-beta 1 (TGF-beta 1) on total protein, collagen or non-collagenous protein and sulphated glycosaminoglycan synthesis. These parameters were determined by assessment of the incorporation by monolayer cultures of early passage chondrocytes of [3H]leucine, [14C]proline and [35S]sulphate respectively, followed by partial molecular characterization. Basic FGF enhanced total protein synthesis with a half-maximal effective concentration of 270 +/- 60 pmol/l (mean +/- S.E.M., four animals) and was sixfold more active on a molar basis than IGF-I or insulin, and 28-fold more active that IGF-II which is the endogenously synthesized IGF. The actions of basic FGF were additive to those of IGF-I or insulin. More detailed analysis of extracellular-matrix component synthesis showed that basic FGF, IGF-I and insulin each caused significant increases in the synthesis of collagen and sulphated glycosaminoglycans. TGF-beta 1 had no effect on total protein synthesis by chondrocytes when present alone at concentrations of 200 pmol/l or less, but was inhibitory at 400 pmol/l. However, the use of this parameter masked a stimulatory action of 50 or 100 pmol TGF-beta 1 on sulphated glycosaminoglycan synthesis and a relative shift in the ratio of collagen: non-collagenous protein synthesis in favour of the former. A synergistic interaction existed between TGF-beta 1 (20-100 pmol/l) and basic FGF which potentiated total protein and collagen synthesis, and their actions on sulphated glycosaminoglycan production were additive. The same concentrations of TGF-beta 1 inhibited the ability of IGF-I or insulin to stimulate total protein or collagen synthesis, but were additive to their stimulatory effects on sulphated glycosaminoglycan synthesis. The results suggest that matrix-molecule composition and the anabolic status of the epiphyseal growth-plate may be modulated in utero by multiple interactions between peptide growth factors produced locally, such as basic FGF, IGF-II and TGF-beta 1, and circulating hormones such as insulin and IGF-I.

Animals↗
PubMed1992

Basic fibroblast growth factor is synthesized and released by isolated ovine fetal growth plate chondrocytes: potential role as an autocrine mitogen.

Basic fibroblast growth factor (basic FGF) is a mitogen for isolated epiphyseal growth plate chondrocytes. To determine whether basic FGF might function as an autocrine stimulus to longitudinal skeletal growth in utero, we investigated the synthesis and release of basic FGF by isolated growth plate chondrocytes from the ovine fetus, the expression of mRNA for a high affinity basic FGF receptor by these cells, and the contribution of endogenous basic FGF to the DNA synthetic rate of the cells in vitro. Chondrocytes were isolated from the proximal tibial growth plate of the lamb fetuses between 35 and 132 days' gestation using collagenase, and were cultured in monolayer before use between passages 3 and 6. Viability was confirmed over the duration of the experiments by the exclusion of trypan blue, and an absence of lactate dehydrogenase accumulation in conditioned medium. Immunocytochemistry of chondrocyte monolayers showed immunoreactive basic FGF to be present in the cytoplasm of approximately 80% of sub-confluent cells which was accompanied by pronounced nuclear staining in approximately 30% of cells. Serum-free, conditioned culture medium, extracellular matrix and chondrocyte cytoplasm contained 52 +/- 2 pM/micrograms DNA, 66 +/- 2 pM/micrograms DNA and 22 +/- 3 pM/micrograms DNA basic FGF, respectively (mean +/- S.E.M., n = 8 fetuses), for cells obtained from animals of 35-40 days' gestation when assessed by radioimmunoassay. Chondrocyte-conditioned medium increased endothelial cell proliferation in vitro (a specific bio-assay for basic FGF and related peptides); and the mitogenic activity was removed from conditioned medium by incubation with heparin-Sepharose demonstrating that this was due to heparin-binding protein(s). Western blot analysis of conditioned medium using a specific basic FGF antibody revealed a single immunoreactive protein of approximately 18 kDa molecular size. The appearance of radiommunoassayable basic FGF in conditioned medium, extracellular matrix, and chondrocyte cytoplasm observed during culture was blocked by co-incubation with cycloheximide. The levels of immunoreactive basic FGF present in each compartment decreased with gestational age as did basal DNA synthetic rate assessed by the incorporation of [3H] thymidine. Incubation of chondrocytes with transforming growth factor beta, resulted in a significant increase while exposure to insulin-like growth factors or insulin caused a decrease, in the content and release of basic FGF. Basic FGF presence was unaltered when medium was supplemented with varying amounts of glucose (2.7-16.7 mM). In situ hybridization on cell monolayers using a cRNA probe encoding the high affinity flg receptor for FGFs showed an abundant expression of mRNA for the receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Similar distribution of insulin-like growth factor binding proteins-1, -2, -3 in human fetal tissues.

The actions of insulin-like growth factors (IGFs) are modulated by several specific binding proteins (IGF BPs). Since the anatomical distribution of IGF BPs is likely to dictate IGF bioavailability we used immunocytochemistry to localize IGF BP-1, -2, and -3 in early second trimester human fetal tissues. Primary antisera were directed against hIGF BP-1, bIGF BP-2 and hIGF BP-3 respectively, and showed less than 5% cross-reaction with heterologous IGF BP species. The distribution of immunopositive staining was similar for each IGF BP in many tissues being prominent in the epithelial lining of the gut, kidney and lung; in epidermis, adrenal cortex and pancreatic endocrine tissue; and in association with membranes of skeletal muscle fibres and cardiocytes. Unlike IGF BP-1 -2, IGF BP-3 was barely detectable in liver and absent from epiphyseal chondrocytes. Conversely, IGF BP-3 alone was visualized within neurons of the cerebral cortex. The co-distribution of IGF BPs in many human fetal tissues suggests that they may co-ordinately regulate IGF bioavailability in target tissues and modify IGF: receptor interactions.

Blotting, Western↗
PubMed1992

Cell cycle-dependent localization of immunoreactive basic fibroblast growth factor to cytoplasm and nucleus of isolated ovine fetal growth plate chondrocytes.

Basic fibroblast growth factor (basic FGF) is a potent mitogen for chondrocytes in vitro and is present in developing cartilage in vivo. Studies of intracellular basic FGF localization in other cell types have revealed a transient nuclear presence. We have examined ovine fetal growth plate chondrocytes for the presence of intracellular basic FGF by immunocytochemistry. Chondrocytes were isolated from the proximal tibial growth plate of lamb fetuses between 75 and 80 days' gestation using collagenase, and were cultured in monolayer before use between passages 3 and 6. In non-synchronized cell cultures 58 +/- 6% of cells (mean +/- s.d., n = 3) demonstrated cytoplasmic staining for immunoreactive basic FGF. Of these cells, 18 +/- 3% also exhibited strong nuclear staining. Chondrocytes were growth-restricted and restarted into the cell cycle with 2% (vol/vol) fetal calf serum. The timing of S phase was followed by nuclear labelling of nuclei with [3H] thymidine followed by autoradiography, or by the incorporation of [3H] thymidine into trichloroacetic acid-precipitable DNA in parallel cultures. A cytoplasmic presence of immunoreactive basic FGF did not appear, following immunocytochemistry, until the second half of G1 with 97% of cells immunopositive 2 hr prior to S phase. Nuclear staining for basic FGF appeared 2 hr before peak nuclear labelling index, and 56% of cell nuclei were immunopositive. Following entry into S phase cytoplasmic and nuclear basic FGF immunostaining rapidly disappeared. When these experiments were repeated with or without the presence of anti-basic FGF antibody or heparin, the presence of the antibody significantly reduced peak [3H] thymidine incorporation into DNA during S phase while exposure to heparin increased this. However, the proportion of cells demonstrating cytoplasmic or nuclear staining for immunoreactive basic FGF, and the time of onset of staining, were unaltered. Incubation of cells with suramin blocked subsequent DNA synthesis and no intracellular basic FGF was visualized. Cell-conditioned culture medium, extracellular matrix and cytoplasm from synchronized cultures of chondrocytes were taken at time points throughout the cell cycle and assessed for basic FGF content by radioimmunoassay. Basic FGF was detectable in each compartment and steadily rose throughout the second half of G1 to reach maximum values around the S phase. The accumulation of basic FGF in medium, matrix and cytoplasm was blocked by the presence of cycloheximide.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗