Insulin-like growth factor-I as an amplifier of follicle-stimulating hormone action: studies on mechanism(s) and site(s) of action in cultured rat granulosa cells.

The ovarian granulosa cell has recently been shown to be a site of insulin-like growth factor-I (IGF-I) production, reception, and action. In large measure, IGF-I action (in the rat) appears contingent upon its ability to synergize with FSH, a major promoter of granulosa cell differentiation. It is the objective of the in vitro studies reported herein to elucidate the cellular mechanism(s) whereby IGF-I amplifies FSH hormonal action, placing special emphasis on the potential role of the putative intracellular second messenger cAMP in this regard.

[Relation between the occurrence of antibodies against Toxoplasma gondii and clinical findings in cats].

Within a three-year period, 178 clinically healthy and 442 sick cats (patients of the Clinic for Small Animal Diseases of the University of Veterinary Medicine, Brno) were examined for the presence of antibodies to Toxoplasma gondii. Antibodies to T. gondii were detected in 34.

[Diagnosis and prevention of feline toxoplasmosis].

At the "Small Animal Clinic of the University of Veterinary Science" in Brno during four years 442 sick and 178 clinically normal cats were examined in regard to incidence and diagnosis of toxoplasmosis. Using the Sabin-Feldman reaction, antibodies against T.gondii were found in 40.

[Incidence of antibodies to Toxoplasma gondii in cats from Brno and the surrounding area].

In the course of three years, 620 cats of all age categories were investigated for the occurrence of antibodies to Toxoplasma gondii. The serological examinations included the Sabin-Feldman reaction (SFR), complement-fixation reaction (CFR) and microprecipitation in agar gel (MPA), according to methods prescribed for use in Czechoslovakia. When the Sabin-Feldman reaction was used, 250 (40.

Characterization and regulation of a specific cell membrane receptor for somatomedin-C/insulin-like growth factor I in cultured rat granulosa cells.

The ovarian granulosa cell has recently been found to be a site of somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) production, reception, and action, thereby raising the prospect of a novel autocrine control mechanism concerned with granulosa cell ontogeny. It is the objective of the in vitro studies reported herein to explore the characteristics of the murine granulosa cell membrane Sm-C/IGF-I receptor and its regulation by gonadotropic, lactogenic, and beta 2-adrenergic signalling. Provision of FSH (150 ng/ml) to granulosa cells from immature rats cultured for 72 h under serum-free conditions resulted in a 3.

Identification by immunoblotting of somatostatin proforms in a rat pancreatic cell line.

The immunoblotting technique is applied to the analysis of "somatostatin" compounds secreted by R.I.N.

Vasoactive intestinal peptide receptors in pancreas and liver. Structure-function relationship.

In purified rat pancreatic plasma membranes, (D-Phe4)PHI interacts as a selective VIP agonist for rat pancreatic VIP-preferring receptors, based on binding selectivity and adenylate cyclase activation, therefore allowing us to discriminate between the participation of VIP-preferring and secretin-preferring receptors in VIP stimulation. VIP-preferring receptors also bind GRF. They rely on disulfide bridges for their functional integrity.

Mechanisms of lithium-vasopressin interaction in rabbit cortical collecting tubule.

In single cortical collecting tubules (CCT) of the rabbit, guanosine 5'-triphosphate (GTP) increased the arginine vasopressin (AVP)-stimulated adenylate cyclase (AC) by 60% (P less than 0.05). In contrast, guanosine 5' O-(2-thio)-diphosphate (GDP-beta S), a competitive inhibitor of GTP action on the stimulatory guanine regulatory protein (Ns), reduced the AVP-stimulated AC activity by 72% (P less than 0.

Chemical, immunological and biological properties of peptides like vasoactive-intestinal-peptide and peptide-histidine-isoleucinamide extracted from the venom of two lizards (Heloderma horridum and Heloderma suspectum).

Having previously isolated helodermin, the major peptide like vasoactive-intestinal-peptide and peptide-histidine-isoleucinamide, from the venom of the lizard Heloderma suspectum, we decided on a systematic exploration of all (VIP-PHI)-like peptides present in the venom of another lizard of the Helodermatidae family: Heloderma horridum. Six (VIP-PHI)-like peptides (PHH1 to 6) were purified to homogeneity from the venom of the lizard H. horridum with PHH3 and PHH4 representing two minor forms.

Lentropin, a protein that controls lens fiber formation, is related functionally and immunologically to the insulin-like growth factors.

Lentropin, a factor present in the vitreous humor of the eye, stimulates lens fiber differentiation from chicken embryo lens epithelial cells in vitro. Lentropin has been partially purified but has not been isolated in sufficient quantity or purity for direct comparison with other growth and differentiation factors. Previous studies have shown that insulin and fetal bovine serum share with lentropin the ability to stimulate lens fiber formation from cultured epithelial cells.

Derivation of monoclonal antibodies to human somatomedin C/insulin-like growth factor I.

Somatomedin C, also called insulin-like growth factor I (Sm-C/IGF-I), is a highly conserved polypeptide required for the proliferation of many cell types. Since several attempts in our laboratory to recover monoclonal antibody-secreting hybrids to this peptide by the direct fusion of hyperimmunized splenocytes with myeloma cells had been unsuccessful, we modified our approach by coculturing hyperimmunized BALB/c splenocytes and a small amount of the antigen for 5 days prior to fusion with the P3X63Ag.8.

Partial characterization of a somatomedin-like peptide from the medium of cultured rat Sertoli cells.

A peptide that is recognized by antibodies to human somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) has been partially purified from cultured Sertoli cells prepared from sexually immature rats. The mol wt of this peptide is about 25,000, as determined by gel filtration chromatography and immunoblot analysis of samples resolved by polyacrylamide gel electrophoresis. Isoelectric focusing indicated that the isoelectric point of this peptide was near neutrality.

Rapid purification of Bordetella pertussis toxin by alternating affinity and hydrophobic chromatography.

Pertussis toxin was purified to homogeneity from a 2-day culture supernatant of Bordetella pertussis by stepwise elution from three columns of, consecutively, Blue Sepharose, phenyl Sepharose, and hydroxyapatite. The toxin was eluted from Blue Sepharose and hydroxyapatite by high ionic strength and from phenyl Sepharose with low ionic strength and with 17% glycerol. Toxin fractions from one chromatographic column were immediately charged on the next column, saving laborious and time-consuming concentration or dialysis steps.

[Incidence of Toxoplasma gondii oocysts in cat feces].

Within two years and a half, the faeces of 620 cats coming from Brno and the area around the city were subjected to parasitological examination with special regard to the occurrence of the oocysts of Toxoplasma gondii. Sucrose solution at the specific weight of 1,150 was used as flotation medium. Oocysts of Toxoplasma gondii were eliminated by eight cats (1.

Insulin-like growth factor II binding to the type I somatomedin receptor. Evidence for two high affinity binding sites.

We have previously shown that the antireceptor antibody alpha IR-3 inhibits binding of 125I-somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) to the 130-kDa alpha subunit of the type I receptor in human placental membranes, but does not block 125I-insulin-like growth factor II (IGF-II) binding to a similar 130-kDa complex in these membranes. To determine whether the 130-kDa 125I-IGF-II binding complex represents a homologous receptor or whether 125I-IGF-II binds to the type I receptor at a site that is not blocked by alpha IR-3, type I receptors were purified by affinity chromatography on Sepharose linked alpha IR-3. The purified receptors bound both 125I-Sm-C/IGF-I and 125I-IGF-II avidly (KD = 2.

Follicle-stimulating hormone enhances somatomedin C binding to cultured rat granulosa cells. Evidence for cAMP dependence.

The ovarian granulosa cell has recently been shown to be the site of Somatomedin C (Sm-C) production, reception, and action. To further elucidate the relevance of Sm-C to granulosa cell physiology, we have undertaken to study the regulation of its receptor under in vitro conditions using a primary culture of rat granulosa cells. Granulosa cells cultured without treatment for 72 h displayed limited, albeit measurable, specific Sm-C binding.

Synergistic interactions of somatomedin-C with adenosine 3',5'-cyclic monophosphate-dependent granulosa cell agonists.

Recent studies have demonstrated the ability of somatomedin-C (Sm-C) to synergize with follicle-stimulating hormone (FSH) in the activation of cultured rat granulosa cell progesterone biosynthesis as well as the induction of luteinizing hormone (LH) receptors. Neither effect could be attributed to Sm-C-enhanced granulosa cell survival or replication, but could be accounted for, in part, by increased adenosine 3',5'-cyclic monophosphate (cAMP) generation. The present study was undertaken to determine if the synergistic property of Sm-C is FSH-selective and hence limited in relevance to follicular maturation, as well as to clarify further the role of cAMP in Sm-C-amplified agonist action.

Independent and synergistic actions of somatomedin-C in the stimulation of proteoglycan biosynthesis by cultured rat granulosa cells.

The role of somatomedin-C (Sm-C) in the regulation of granulosa cell proteoglycan biosynthesis was investigated in vitro in a primary culture of rat granulosa cells labeled with [35S]sulfate. Basal [35S]sulfate incorporation into extracellular proteoglycans was increased by 93 percent in response to treatment with highly purified Sm-C (50 ng/ml) by itself. Whereas treatment with a minimally effective dose of FSH (20 ng/ml) alone produced a 43 percent increase over basal levels in extracellular [35S]sulfate-labeled proteoglycans, concurrent treatment with Sm-C yielded a 2.

Identification of two pro-VIP forms in a human neuroblastoma cell line.

The immunoreactivity of VIP and PHI standards, immobilized on a nitrocellulose membrane, was first assayed with various detection procedures. For VIP, the double bridge peroxidase-antiperoxidase (PAP) method was the most sensitive procedure, giving a detection limit of 0.1-0.

Effector mechanisms of peptides of the VIP family.

The present review is focused on the exocrine pancreas and liver where the only known effector mechanism of VIP is the activation of adenylate cyclase in plasma membranes. A two-state model of activation-deactivation of the enzyme visualizes the participation of VIP receptors and Ns, the guanyl nucleotide stimulatory protein of adenylate cyclase. In the rat pancreas, VIP and GRF receptors are indistinguishable and disulfide bridges influence their functional integrity.

Somatomedin-C as an amplifier of follicle-stimulating hormone action: enhanced accumulation of adenosine 3',5'-monophosphate.

Somatomedin-C (Sm-C) has recently been found to amplify the FSH-mediated acquisition of granulosa cell progestin biosynthetic capacity, aromatase activity, and LH receptors, an effect distinct from its established replicative property. To further characterize the cellular mechanism(s) underlying the synergistic interaction of Sm-C with FSH, we have set out to evaluate the intermediary role of cAMP in this regard. Isolated granulosa cells from immature hypophysectomized diethylstilbestrol-treated rats were cultured for up to 3 days under serum-free conditions.

Interaction of the monoclonal antibodies alpha IR-1 and alpha IR-3 with insulin and somatomedin-C receptors.

alpha IR-3, a monoclonal antibody that interacts with the somatomedin-C receptor, inhibited the binding of somatomedin-C, but not of insulin, to human placental membranes and intact IM-9 cells. alpha IR-1, a monoclonal antibody that interacts with the insulin receptor, did not inhibit the binding of either hormone. Inhibition of somatomedin-C binding by alpha IR-3 was mainly due to a decrease in its affinity.

Somatomedin-C-mediated potentiation of follicle-stimulating hormone-induced aromatase activity of cultured rat granulosa cells.

We have recently observed that nanomolar concentrations of exogenously added somatomedin-C (Sm-C) are capable of synergizing with FSH in the induction of cultured rat granulosa cell progesterone biosynthesis and LH receptors without altering granulosa cell survival or replication. To further characterize the cytodifferentiative properties of Sm-C, we have undertaken to investigate whether the acquisition of granulosa cell aromatase activity is also subject to modulation by this intraovarian peptide. Granulosa cells from immature hypophysectomized diethylstilbestrol-treated rats were initially cultured for up to 3 days in an androstenedione-free medium, during which time aromatase activity was induced by FSH in the absence or presence of Sm-C (treatment interval).