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F A Gonzalez

Publications and source records attributed to F A Gonzalez.

At least 37 records · Page 2Linked to original sources
PubMed1990

Covalent incorporation of 3'-O-(4-benzoyl)benzoyl-ATP into a P2 purinoceptor in transformed mouse fibroblasts.

ATP, 3'-O-(4-benzoyl)benzoyl-ATP (BzATP), a photoaffinity analog of ATP, and several other ATP analogs induced an increase in plasma membrane permeability to monovalent ions and normally impermeant metabolites, including nucleotides, in transformed 3T6 mouse fibroblasts. The rank order of agonist potency for induction of nucleotide channels was BzATP (EC50 = 15 microM) greater than ATP (EC50 = 50 microM) approximately adenosine 5'-O-(1-thiotriphosphate) (ATP alpha S) greater than 2-methylthio-ATP (EC50 = 75 microM) approximately 3'-amino-3'-deoxy-ATP greater than adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S) (EC50 = 175 microM). Long wavelength UV illumination of 3T6 cells in the presence of greater than or equal to 20 microM BzATP at 4 degrees C, a nonpermeabilizing temperature, followed by removal of unbound BzATP, resulted in the efflux of 86Rb+ and the release of a prelabeled pool of cytoplasmic nucleotides when the temperature was shifted to 37 degrees C. Photoincorporation of BzATP was inhibited by ATP, ATP alpha S, ATP gamma S, and other ATP analogs that induced an increase in plasma membrane permeability to nucleotides in 3T6 cells under nonphotoactivating conditions. GTP, ITP, UTP, adenosine, and ATP analogs that did not alter plasma membrane permeability to nucleotides under nonphotoactivating conditions also had no effect on BzATP photoincorporation. Photoincorporation of BzATP occurred optimally between pH 6.6 and pH 8.2 but was inhibited at pH 6.0. Photoincorporation of BzATP was also modulated by the osmolarity and the divalent cation concentration of the assay medium. The increase in plasma membrane permeability to nucleotides induced by photoincorporated BzATP occurred at the same rate and had the same temperature, pH, ionic strength, and divalent cation requirements as the increase in plasma membrane permeability to nucleotides induced by ATP and BzATP under nonphotoactivating conditions. These findings support the hypothesis that BzATP can be covalently incorporated into a P2 purinoceptor in 3T6 cells that is coupled to plasma membrane channels for ions and other metabolites.

Adenine Nucleotides↗
PubMed1990

Activation of early events of the mitogenic response by a P2Y purinoceptor with covalently bound 3'-O-(4-benzoyl)-benzoyladenosine 5'-triphosphate.

3'-O-(4-Benzoyl)benzoyl-ATP (BzATP), a photoaffinity analog of ATP, was used as a ligand for a P2Y purinoceptor (adenine nucleotide receptor) present in intact Swiss 3T3 and 3T6 cells and A-431 epidermoid carcinoma cells. Photolysis of serum-starved cells in the presence of 10-50 microM BzATP, followed by extensive washing to remove unincorporated BzATP, induced the release of arachidonic acid. A trace (less than 0.01%) of photoincorporated BzATP was as effective as when 50 microM BzATP or ATP was contained in the incubation medium during the assay. Photoincorporated BzATP also stimulated the production of prostaglandin E2 and the accumulation of cyclic AMP. In previous studies, we demonstrated that these three events are obligatory early steps in a pathway leading to DNA synthesis in the above cell lines. The evidence indicated that the purinoceptor activated by extracellular ATP or BzATP was linked to a pertussis toxin-sensitive GTP-binding protein. Consistent with these observations, we now find that pertussis toxin inhibits the effect of photoincorporated BzATP on arachidonic acid release. These results indicate that BzATP is an effective agonist for the P2Y purinoceptor concerned with stimulation of DNA synthesis in 3T3, 3T6, and A-431 cells. Furthermore, after photolysis it becomes irreversibly associated with intact cells and promotes the activation of early events required for DNA synthesis.

Adenosine Triphosphate↗
PubMed1989

Two distinct receptors for ATP can be distinguished in Swiss 3T6 mouse fibroblasts by their desensitization.

The stimulation of calcium efflux from Swiss 3T6 mouse fibroblasts by extracellular ATP was studied. It was found that the cells could be desensitized to ATP by a previous exposure to the nucleotide, lending support to the theory that this is a receptor mediated process. Another ATP-receptor mediated process in Swiss 3T6 cells, that is also subject to desensitization, causes the permeabilization of the plasma membrane to nucleotides and other normally impermeant compounds [Gonzalez et al., J. Cell. Physiol. 139:109 (1989)]. Here we demonstrate that selective desensitization of the ATP-dependent calcium mobilization pathway can be achieved without affecting ATP-induced permeabilization. Data are presented in support of the existence of multiple ATP-receptors (purinoceptors) in Swiss 3T6 cells.

Adenosine Triphosphate↗
PubMed1989

Permeabilization of transformed mouse fibroblasts by 3'-O-(4-benzoyl)benzoyl adenosine 5'-triphosphate and the desensitization of the process.

A photoreactive analogue of ATP, 3'-O-(4-benzoyl)benzoyl adenosine 5'-triphosphate (BzATP) altered the plasma membrane permeability of transformed 3T6 mouse fibroblasts to normally impermeant molecules as previously reported for ATP, but at lower concentrations. BzATP-induced permeabilization was modulated by pH, temperature, and the ionic composition of the medium similar to the permeabilizing effects of ATP. Conditions known to enhance ATP-induced permeabilization, such as treatment with the mitochondrial uncoupler carbonyl cyanide-m-chlorophenylhydrazone (CCCP) or the Ca2+-calmodulin antagonist trifluoperazine also enhanced BzATP-induced permeabilization. Conditions inhibitory to ATP-induced permeabilization, including chloride replacement or treatment with furosemide or dithiothreitol (DTT), inhibited permeabilization induced by BzATP. The ionic strength of the medium modulated the responsiveness of the cells to ATP and BzATP; a decrease in the ionic strength below isotonicity increased the sensitivity of the cells to the nucleotides, whereas an increase in ionic strength above isotonicity inhibited permeabilization. Prolonged exposure to ATP under non-permeabilizing conditions caused the cells to become insensitive to ATP and BzATP. The densensitization phenomenon provides support for the theory that the permeabilization process is mediated by a receptor for ATP.

Adenosine Triphosphate↗
PubMed1989

Receptor specific for certain nucleotides stimulates inositol phosphate metabolism and Ca2+ fluxes in A431 cells.

We have recently reported that extracellular ATP induces a transient rise in cytosolic free Ca2+ [( Ca2+]i) in individual human epidermoid carcinoma A431 cells (Gonzalez et al: Journal of Cellular Physiology 135:269-276, 1988). We have now studied nucleotide specificity and desensitization for several early responses. Extracellular ATP (5-100 microM) caused the rapid formation of inositol trisphosphate and later its metabolites, inositol bisphosphate and inositol monophosphate. ATP also induced the efflux of 45Ca2+ from pre-loaded cells. In addition, an increase in the rate of influx of 45Ca2+ stimulated by extracellular ATP was detected. Based on measurements of 45Ca2+ efflux and influx, desensitization studies, and chlortetracycline fluorimetry, we conclude that ATP mobilizes Ca2+ from internal stores and also stimulates entry across the plasma membrane. These effects were also displayed by UTP and to a lesser extent by ITP, while other nucleoside triphosphates as well as ADP, AMP, and adenosine, were inactive. Furthermore, desensitization of the response to ATP and UTP was seen after prolonged exposure to either nucleotide. This was specific for the nucleotide receptor since a response to bradykinin was not affected by the ATP pretreatment, although pretreatment with phorbol ester inhibited responses to both the nucleotides and bradykinin. Quantitative data on rate of recovery from the desensitized state and the response of desensitized cells to greatly elevated levels of ATP are presented. Extracellular ATP stimulated another early change previously reported for epidermal growth factor, namely, the phosphorylation of an 81-kDa cytoskeletal protein. The stimulation of these events involves an ATP receptor whose properties differ from other ATP receptors that have been described.

Adenosine Triphosphate↗
PubMed1989

Extracellular ATP induces the release of calcium from intracellular stores without the activation of protein kinase C in Swiss 3T6 mouse fibroblasts.

Exposure of Swiss 3T6 mouse fibroblasts to extracellular ATP stimulated the formation of inositol phosphates and mobilized intracellular calcium. The mobilization of intracellular calcium was verified by imaging of fura-2 fluorescence in individual cells and by monitoring the efflux of 45Ca2+ from preloaded cells. However, we found no activation of protein kinase C as measured by phosphorylation of an 80-kDa acidic protein and by transmodulation of the receptor for epidermal growth factor. A careful examination of the kinetics of the phosphorylation reaction (from 30 sec to 10 min) revealed no activation of protein kinase C by extracellular ATP at any time. The lack of activation of protein kinase C was demonstrated even when a concentration of ATP 10-fold higher than that required to give a strong Ca2+ signal was used. Extracellular ATP did not inhibit protein kinase C activation by fetal bovine serum, platelet-derived growth factor, or phorbol esters. The effects of ATP were also produced by UTP but not by ADP, AMP, or adenosine. These findings demonstrate that it is possible to induce the mobilization of intracellular calcium by an inositol phosphate-mediated pathway without the activation of protein kinase C.

Adenosine Triphosphate↗
PubMed1989

The development and implementation of a computerized on-line obstetric record.

We developed and implemented a completely paperless and on-line obstetric record in the high-risk obstetric clinics at Columbia Presbyterian Medical Center. Patient care and interactions are input directly into the computer by the health care providers. Laboratory information is transferred automatically from the Laboratory Information Service into the computerized prenatal record. The system has been in continuous operation for 2 years and is highly regarded. Problems such as illegible handwriting, missing records, and missing laboratory data have disappeared. Research and data query capabilities have been facilitated. The feasibility and applicability of a computerized record replacing the paper record has been demonstrated.

Computers↗
PubMed1988

The rapid desensitization of receptors for platelet derived growth factor, bradykinin and ATP: studies on individual cells using quantitative digital video fluorescence microscopy.

The rise in free cytosolic Ca2+ of individual response to growth factors was studied in serum starved cultures of 3T3 fibroblasts. Quantitative digital video fluorescence microscopy revealed that with platelet derived growth factor (PDGF) there was a lag period between stimulation and Ca2+ response, with considerable cell-to-cell variation, whereas ATP, bradykinin and fetal calf serum induced an immediate, synchronous response. A coverslip with attached cells was mounted on a small flow chamber, allowing complete change of medium in 2 sec. Using this technique, homologous desensitization to a second addition of agonist 2 min after removal of the first addition was found for all agonists. Unusual heterologous desensitization was observed in that PDGF desensitized the cells to the other agonists, yet the reverse did not occur.

Adenosine Triphosphate↗
PubMed1988

Studies on the increase in cytosolic free calcium induced by epidermal growth factor, serum, and nucleotides in individual A431 cells.

The response of cytosolic calcium [Ca2+]i to epidermal growth factor (EGF), fetal calf serum, and nucleotides was determined in individual A431 cells, using the fluorescent probe fura-2 and quantitative digital video fluorescence microscopy. In the presence of 1 mM external Ca2+, EGF caused a rapid rise in [Ca2+]i, followed by a slower and variable decrease. The cells responded after a lag that varied from 10 to 30 seconds, and there was considerable cell-to-cell variation in extent of the rise in [Ca2+]i. A second challenge with EGF gave negative results. No response was obtained in nominally Ca2+-free medium supplemented with 100 microM EGTA. Somewhat similar results were obtained with fetal calf serum except that a rise in [Ca2+]i was observed both in the presence and absence of external Ca2+. The A431 cells responded to external ATP with a rise in [Ca2+]i in less than 10 seconds, both in Ca2+-containing and Ca2+-free media. A coverslip with attached cells was mounted on a small chamber, allowing complete change of medium in 2 seconds. A nearly full response was obtained with only 10 seconds of contact of cells with ATP-containing medium. After washing out ATP, there was little or no response to a second addition given 100 seconds after the first. However, a second response was obtained when the concentration of agonist was increased 10-20-fold. These data favor the idea of receptor desensitization. Both homologous and heterologous receptor desensitization was observed. A transient rise in [Ca2+]i was also noted with UTP, while ITP and CTP were inactive.

Adenosine Triphosphate↗
PubMed1987

The antitumor drug 3-nitrobenzothiazolo(3,2-a)quinolinium chloride (NBQ): effects on lens regeneration and interaction with DNA of Notophthalmus viridescens.

We have studied the effect of 3-nitrobenzothiazolo(3,2-a)quinolinium (NBQ) on the regeneration of the lens in adult newt Notophthalmus viridescens. NBQ has marked cytotoxic effects in tumor cells, intercalates DNA, and was found to enhance lens regeneration. Newt liver DNA was isolated, and the thermal denaturation temperature (Tm) determined to be 76.6% +/- 0.8%. The G-C content was determined to be 44.0% +/- 0.4% and 45.0% +/- 0.1%. Parameters of NBQ binding to newt DNA were determined by spectrophotometric methods and compared with those obtained for calf thymus and Micrococcus lysodeikticus. The association constant, K(o), was found to be 1.1 x 10(+5) M-1 with a site-size parameter, n, of 8.7 nucleotides. No explanation is apparent for the paradoxical stimulation of lens regeneration.

Animals↗
PubMed1987

Fetal gender effects on maternal serum prolactin levels.

Circulating maternal prolactin (PRL) levels have been reported to be higher in term pregnancies yielding male infants. The mechanism for this gender difference is unknown, but we theorized that it was mediated through the fetal adrenal cortex. To test this theory we measured circulating PRL and estriol (E3) concentrations with radioimmunoassay in 37 pregnant women at 34 and 36 weeks' gestation. We then separated the groups by newborn gender. Maternal serum PRL levels were significantly higher in the women bearing male fetuses. There was no significant difference by gender in E3 concentrations, and there was no PRL surge corresponding to the E3 surge at 34-36 weeks' gestational age. There was no correlation between E3 and PRL levels. Transmission of the fetal gender effect on maternal PRL does not appear to be mediated through the fetal adrenal as measured by the fetoplacental production of E3. The effect probably is mediated by the fetal gonad.

Adrenal Cortex↗
PubMed1983

Ontogenesis and sex differences in rabbit fetal adrenal phenylethanolamine N-methyltransferase.

The development of the sympatho-adrenal system is important for neonatal adaptation to extrauterine life. On the basis of previous studies suggesting relatively accelerated adrenal maturation in the female rabbit fetus, we conducted an ontogenetic study of male-female differences in adrenal levels of phenylethanolamine N-methyltransferase (PNMT), the terminal enzyme in epinephrine biosynthesis. Geometric mean adrenal PNMT activities increased significantly from 5.1 +/- 0.07 pmol/pair adrenals/h for females and 3.3 +/- 1.21 for males at 24 days gestation to 32.1 +/- 1.07 for females and 29.2 +/- 1.08 for males at 31 days gestation. These increases with gestational age were highly significant (p less than 0.001). Analysis of variance showed significantly increased activity in female versus male littermates (p less than 0.025). No significant differences were noted among the female fetuses grouped according to their numbers of male neighbors. These results demonstrate that adrenal PNMT increases significantly with advancing gestational age and that female fetuses have significantly increased activity relative to their male littermates. The near neighbor fetal data do not suggest that this effect is mediated by a humoral agent which is transferable by the uterine vasculature or by interamniotic diffusion. We speculate that sex differences in sympathoadrenal development may explain the lower neonatal morbidity and mortality in female infants.

Adrenal Glands↗
PubMed1981

Time-course effects of adrenergic and cholinergic antagonists on systemic arterial blood pressure, heart rate and temperature in conscious squirrel monkeys.

Mean arterial blood pressure, heart rate, and rectal temperature were measured from conscious, chair-restrained squirrel monkeys prepared with chronically indwelling arterial and venous catheters and temperature probes to determine the magnitude and duration of the effects of acute intravenous injections of propranolol, phentolamine and methyl atropine. The data indicate a predominant influence of the sympathetic nervous system in the regulation of cardiovascular activity resting squirrel monkeys.

Animals↗
PubMed1981

Ectopic pregnancy. A prospective study on differential diagnosis.

This study analyzes the clinicopathologic findings in patients with ectopic pregnancy (EP), and deals with the differential diagnosis of the EP, intrauterine pregnancy (IUP), and pelvic inflammatory disease (PID). We evaluated 346 patients with suspected EP. Among those, 119 patients had EP, 82 had IUP, and 55 had PID without pregnancy. The incidence of EP was 1/32.9 live births. Comparing with the other groups, the patients with EP were slightly older, gave a history of previous pregnancies, had acute abdominal pain, nausea, vomiting, dizziness, and fainting, and had direct and rebound abdominal tenderness, pain on motion of the cervix, absence of a pelvic mass, and bilateral adnexal or cul de sac fullness. Culdocentesis was accurate in 95.1% of EP cases. Salpingectomy was performed in 89.9% of the patients with EP. The patients with EP had gross evidence of PID at the surgery in 31% and microscopic evidence of tubal inflammation in 19.4% of cases.

Adolescent↗
PubMed1981

Ectopic pregnancy. A retrospective study of 501 consecutive patients.

We reviewed the records of 501 patients with ectopic pregnancy (EP) seen at the Kings County Hospital during a five-year period (January 1973-December 1977). Our population characteristics and anamnestic data correlated well with those reported in the literature, except for lower incidence of a previous pelvic infection. Abdominal pain, amenorrhea, and vaginal bleeding were the most common presenting symptoms. While the ultrasound studies demonstrated adnexal masses of a non-specific nature, the laparoscopy constituted an accurate diagnostic tool. Ruptured EP was found in 339 patients (67.6%). Salpingectomy only was the mode of treatment in 369 cases (73.6%). In 28.4% of the cases there a microscopic evidence of chronic inflammatory changes of the tube. There were two fatalities. This study appears to indicate an increasing incidence of EP in our institution, along with, and despite, a decreasing frequency of chronic pelvic inflammatory disease in these patients.

Abdomen↗
PubMed1977

Effects of cocaine and d-amphetamine on behavior maintained under various schedules of food presentation in squirrel monkeys.

Dose-response functions were determined for the effects of cocaine and d-amphetamine on lever-pressing responses maintained under three schedules of food presentation: 1) a simple fixed-ratio schedule, 2) a multiple fixed-ratio, fixed-interval schedule and 3) a second-order fixed-interval schedule with fixed-ratio components. These schedules generated a variety of rates and patterns of responding. The effects of the drugs on response rate depended on the control rates of responding. The highest overall rates of responding were maintained under the fixed-ratio schedule and under the fixed-ratio component of the multiple schedule. Both cocaine and d-amphetamine produced dose-related decreases in these high response rates. Lower overall rates of responding were maintained under the second-order schedule and under the fixed-interval component of the multiple schedule. Intermediate doses of cocaine or d-amphetamine (0.1-1.0 mg/kg) increased these lower rates of responding. Under the second-order schedule and the multiple schedule, local response rates during successive segments of the fixed-intervals were differentially affected by the drugs. Cocaine and d-amphetamine markedly increased low response rates that occurred during initial segments of the fixed intervals, but either had little effect on or decreased higher responses rates that occurred during later segments of the fixed intervals. Cocaine and d-amphetamine had similar qualitative and quantitative effects on responding, but d-amphetamine was longer lasting than cocaine.

Animals↗