Browsing by Author "CAMPINO, C"

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    CERTAIN LARGE FORMS OF CIRCULATING IMMUNOREACTIVE HUMAN GROWTH-HORMONE ARE IN FACT IMMUNOGLOBULINS
    (1990) CAMPINO, C; SZECOWKA, J; MICHELSEN, H; SERONFERRE, M
    To explain frequent discordances between serum GH levels and clinical manifestation of acromegaly, we investigated the possibility that certain immunoglobulins G (IgGs) might be responsible for the displacement of [125I]human (h) GH in the hGH RIA. We incubated dilute sera from seven active acromegalics (basal immunoreactive hGH, 22-313 .mu.g/L) with rat adipocyte plasma membranes adsorbed on polystyrene plates. IgGs that bound to GH receptor sites in the absence and presence of 250 nM hGH (for nonspecific binding) were detected using anti-hIgG (Fc-specific) antibody conjugated with alkaline phosphatase. In this system two of the seven sera studied tested positive for IgGs against GH-binding sites (serum 4 in1:400 dilution, and serum 7 in 1:10 dilution). We studied further the serum with the highest titer. On Sephadex G-100, most of the GH-like immunoreactivity (assayed by RIA) present in serum 4 coeluted with IgGs (assayed by immunodiffussion) as a high mol wt (.gtoreq.150 kDa) component. To confirm its IgG nature, this material was then adsorbed on protein-A-Sepharose and eluted with 0.1 M sodium citrate, pH 3.0. The protein-A-purified IgGs from serum 4 bound specificially to GH receptor sites in adipocyte membranes and displaced [125I]hGH in the hGH RIA. In contrast, IgGs purified from another acromegalic patient (313 .mu.g/L hGH) repeatedly tested negative in the membrane binding assay and hGH RIA. We conclude that some active acromegalics have circulating IgGs that bind both to hGH-specific antibodies in the RIA and to GH receptor sites; certain forms of the socalled big GH may correspond to these IgGs; and possible metabolic effects of these GH-like IgGs should be taken into consideration.
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    GROWTH-HORMONE (GH) RECEPTOR ANTIBODIES WITH GH-LIKE ACTIVITY OCCUR SPONTANEOUSLY IN ACROMEGALY
    (1992) CAMPINO, C; SZECOWKA, J; LOPEZ, JM; MULCHAHEY, J; SERONFERRE, M
    Previous studies in our laboratory have identified a portion of big-big GH as actually being anti-GH receptor immunoglobulins. We now report the isolation of two types of anti-GH receptor antibodies from the serum of active acromegalic patients. One of them (patient A) interferes with the human GH RIA, thus overestimating the real plasma GH values. The other type of immunoglobulin G (IgG; patient B) was detected in an acromegalic patient with almost normal immunoreactive GH level. The main aim of the present study was to explore whether these anti-GH receptor IgGs possess GH-like biological activity. The IgGs of both patients were isolated by chromatography on Sephadex G-100 and then on protein-A-Sepharose. In the bioassay, cultured Nb2 lymphoma cells were incubated with hGH standards and serial dilutions of the purified IgGs, and cell proliferation was used as a measure of biological activity. The IgGs of both patients showed GH-like bioactivities, which, when calculated as equivalents of human GH, correspond to approximately 260 and 120-mu-g/L, respectively. The results suggest that biologically active anti-GH receptor antibodies may contribute in the pathology of some cases of acromegaly.
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    SERUM OSTEOCALCIN IN NORMAL MENSTRUAL-CYCLE
    (1992) MORENO, JML; GONZALEZ, G; CAMPINO, C; SALVATIERRA, AM; CROXATTO, HB
    Serum osteocalcin (OC) was serially measured along an ovulatory menstrual cycle in 4 healthy unmedicated volunteers (age 33-38 years). During the study the women maintained their normal diet and daily physical activity. Starting at days 4-5 of the cycle, blood samples were taken between 09-11 AM every 2 or 3 days for OC, FSH, LH, E2 and P determinations. Daily ultrasound assessment of ovulation was performed in all subjects between days 7-18 of the cycle. Hormone determinations and OC were performed by RIA. While blood levels of FSH, LH, E2 and P changed during the cycle, according to the expected ovulatory pattern, serum OC concentrations remained stable during the cycle in each subject. In conclusion, serum OC is independent of the gonadotropin and ovarian steroid variations during the normal menstrual cycle.
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    YEAST RNA-POLYMERASE .1. A EUKARYOTIC ZINC METALLOENZYME
    (1976) AULD, DS; ATSUYA, I; CAMPINO, C; VALENZUELA, P
    Microwave excitation spectrometry and metal binding inhibition studies showed that Zn is a catalytically essential component of the highly purified RNA polymerase I from yeast, the 1st eukaryotic RNA polymerase I available in quantities sufficient for such studies. It contained 2.4 g-atom of Zn based on a MW of 6.5 .times. 105. Cu, Fe, Mn and Mg were absent, i.e., below the limits of detection, 10-3-10-14 g-atoms. A number of derivatives of 1,10-phenanthroline reversibly inhibited the polymerase catalyzed reaction, apparently by forming a ternary polymerase.cntdot.Zn.cntdot.OP complex while the nonchelating isomer, 1,7-phenanthroline, was ineffective.