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M Macchi

Publications and source records attributed to M Macchi.

28 records · Page 2Linked to original sources
PubMed1987

In vitro binding of cell-specific and ubiquitous nuclear proteins to the octamer motif of the SV40 enhancer and related motifs present in other promoters and enhancers.

We have used the gel retardation and DNase I footprinting assays to investigate the in vitro binding of nuclear proteins to the octamer motif present in domain A of the SV40 enhancer and in other enhancer and promoter elements. Three apparently cell-specific (oct-B1A, oct-B1B and oct-B2) and one ubiquitous (oct-B3) proteins were detected in various lymphoid and non-lymphoid cell extracts. We show that the previously described 'ubiquitous' NF-A1 factor may correspond in fact to two proteins, oct-B1A in HeLa cells and oct-B1B in lymphoid cells. Interestingly, the HeLa cell protein oct-B1A formed a complex with the SV40 octamer, which could be detected in gel retardation, but not in DNase I footprinting assays. This absence of protection from DNase I digestion correlates with the inactivity of the SV40 octamer in HeLa cells in vivo. We have also found that the in vitro interaction between the SV40 octamer motif and the lymphoid cell-specific protein oct-B2 was negatively modulated by a component present in the nuclear extracts from several lymphoid cell lines. The interactions between the multiple octamer-binding proteins and the related octamer motifs present in other promoter and enhancer elements were systematically compared and the possible role of these proteins in the control of transcription is discussed.

Base Sequence↗
PubMed1987

The expression and detection of MHC class I antigens on murine neuroblastoma and ependymoblastoma lines.

It has been reported that human neuroblastoma lines are almost devoid of class I transplantation antigens, while human glioma lines express these antigens. Other studies have also shown a paucity of class I antigens on the murine neuroblastoma line N2A, and the expression of these antigens by the murine ependymoblastoma G26 lines. Such differences might represent heterogeneity in class I antigen expression by different brain cell types, and the importance of this to the immunology of the brain prompted us to re-examine class I expression by these cell lines in more detail. Using an exhaustive number of approaches, we were not able to detect significant differences in class I surface antigen expression between N2A and the G26 lines. We compared the murine neuroblastoma line Cl300 and its cloned derivative, N2A, to the lines G26-20 and G26-24. Antibody-dependent, complement-mediated cytotoxicity revealed detectable levels of both K and D region antigens on these lines. Immunocytofluorometric analysis further confirmed that these lines express high levels of class I antigens, although due to their large sizes, the surface densities of class I antigens on these cells are lower than splenocytes. This lower density of class I molecules did not impede the capacity of either the neuroblastoma or the G26 lines to serve as targets of H-2K- or D-specific T effectors. Finally, comparison of these two cell types for class I RNA transcripts also revealed no difference. Thus, our findings which are the most detailed study of these lines are drastically different from findings in humans as well as earlier findings in the murine system. Likely explanations are discussed and precautions are given for the study of class I antigen expression by these lines.

Animals↗
PubMed1987

In vitro binding of several cell-specific and ubiquitous nuclear proteins to the GT-I motif of the SV40 enhancer.

We have investigated the specific in vitro binding of nuclear proteins from several cell lines to the GT-I motif of the SV40 enhancer which overlaps with the canonical enhancer "core" homology. The binding of three proteins (GT-IA, GT-IB, and GT-IC), one of which (GT-IC) exhibits cell specificity, was detected. Competition and direct binding experiments demonstrated that the two ubiquitous proteins also bind to the GC-rich motif III from the 21-bp repeat upstream element of the SV40 early promoter and that protein GT-IA is most probably the transcription factor Sp1. The third, cell-specific protein GT-IC exhibited a high affinity for both the GT-I motif and an upstream element in the promoter of the mouse beta-major-globin gene, suggesting that this protein can act both as an enhancer and an upstream element trans-acting factor. The good correlation between the known cell-specific in vivo activity of the wild-type and mutated GT-I motif and the cell-specific binding of protein GT-IC in vitro strongly supports the conclusion that this protein is an enhancer factor. Interestingly, its cognate recognition sequence does not coincide with the core homology.

Animals↗
PubMed1987

Dynamics of plasma gonadotropin and sex steroid release in polycystic ovarian disease after pituitary-ovarian inhibition with an analog of gonadotropin-releasing hormone.

To assess the dynamics of the suppression and recovery of plasma gonadotropins and sex steroids during and after inhibition of pituitary-ovarian function by a long-acting agonist GnRH-analog (GnRH-A), eight patients with polycystic ovarian disease were treated with 12 micrograms/kg X day GnRH-A for 56 consecutive days. In response to GnRH-A, these patients had a sharp and pronounced decline of their initially elevated immunoreactive LH and bioactive LH (bioLH) levels. Plasma immunoreactive FSH levels declined more rapidly than did bioLH, but the FSH decline was less sustained. Plasma testosterone, androstenedione, and estrone (E1) levels also declined during GnRH-A administration. The pattern of plasma androgen decrease resembled that of bioLH. There was a positive correlation between bioLH and the two androgens (r = 0.85; P less than 0.05, by Spearman's rank correlation, for both hormones). Cessation of GnRH-A administration was followed by prompt progressive increases in gonadotropin and androgen concentrations to pretreatment values. FSH recovered faster than bioLH. BioLH plasma concentrations reached pretreatment values by day 28. The recovery of plasma androstenedione and testosterone levels correlated positively with that of bioLH. Although plasma E1 levels were higher during the recovery period than during treatment, they never reached the concentrations found during the basal period, whereas estradiol concentrations were slightly but not significantly higher than those in the basal period. As a consequence, the E1 to estradiol ratio, very high in the basal period, approximated unity during recovery. These data indicate that hyperandrogenism in polycystic ovarian disease is gonadotropin dependent and accompanied by a relative abundance of LH bioactivity basally and during GnRH-A administration. Thus, the relative increase in bioLH secretion appears to be independent of the rate of gonadotropin secretion and the circulating sex steroid concentrations.

Adolescent↗
PubMed1986

Effect of gonadotrophin-releasing hormone analogue (GnRH-A) administration on serum gonadotrophin and steroid levels in patients with polycystic ovarian disease.

A gonadotrophin-releasing hormone (GnRH) analogue, D-Ser[TBU]LRH-EA10, (GnRH-A), at a dose of 200 micrograms was given daily for 2 months to 6 women with polycystic ovarian disease (PCO). Prior to therapy the patients presented elevated LH, testosterone (T), oestrone (E1) and dihydrotestosterone (DHT) in the circulation. In response to GnRH-A, these subjects exhibited a marked decrease in circulating T, DHT and androstenedione (A) levels as measured 24 h after GnRH-A injection, by 4 weeks and onwards (P less than 0.05). After 2 weeks of daily administration, the serum LH profile, evaluated by sampling at 2, 4, 7 and 24 h after injection of GnRH-A, was not different from baseline, whereas after 4, 6 and 8 weeks the levels were significantly lower (*P less than 0.01). The profile of serum T levels was unmodified at the second week, but significantly decreased thereafter (*P less than 0.01). At the end of treatment, the E1 concentrations, elevated in pre-injection condition, were markedly decreased. These data demonstrate that in PCO subjects, GnRH-A significantly lowered the elevated levels of androgens commonly found in these patients. The close correlation observed between reduced serum LH and androgen concentrations suggests that pituitary desensitization could be responsible for the reduction in androgen levels, and may be evidence for a gonadotrophin dependence of the elevated concentrations of T in these patients.

Adult↗
PubMed1986

Failure of GnRH analogue to inhibit serum concentrations of testosterone and 17 alpha-hydroxyprogesterone in hCG-substituted hypogonadotropic hypogonadism.

Gonadotropin-releasing hormone analogues (GnRH-A) induce inhibition of testicular function and reduction of serum testosterone (T) in man, but the mechanism involved is still debatable. To elucidate it we studied six patients with hypogonadotropic hypogonadism (HH) in chronic substitution with hCG for correction of androgen deficiency symptoms, and evaluated the effect of addition of GnRH-A to the hCG therapy on plasma levels of T and 17 alpha-hydroxyprogesterone (17 OHP). All patients were treated with 1000 U of hCG in every 3rd day for 24 weeks. After 8 weeks of this regimen, GnRH-A, Buserelin (D-Ser-TBU-EA-LHRH), 200 micrograms per day sc, was added and given for 8 weeks. After cessation of analogue administration patients were followed for 8 further weeks. The levels of the two steroids did not differ markedly in the pre- and post-GnRH-A period. GnRH-A given for two months did not lower T or 17 OHP levels as in eugonadal men after similar treatment. The median T concentrations during GnRH-A tended to be increased, with plasma values higher (P less than 0.025) than the peak values observed during hCG alone. Since administration of Buserelin did not inhibit hCG-sustained steroid levels in these HH patients, it is conceivable that GnRH-A may have lacked a direct inhibitory gonadal effect in such experimental conditions.

17-alpha-Hydroxyprogesterone↗
PubMed1986

Enhancing detection of gonococcus in ejaculates of adult males using sperm dilution.

Specific cultures were used to detect growth of Neisseria Gonorrhoeae (NG) in 90 ejaculates of partners of childless marriages. Although no gonococcal growth was observed in undiluted semen, 9 out of 68 subjects with silent infection presented growth of NG in seminal plasma after dilution 1:2 with saline. It is concluded that semen dilution increases the chances of detection of NG in semen samples of asymptomatic gonococci carriers.

Adult↗
PubMed1981

A study of short-term effect of rehabilitative therapy in chronic obstructive pulmonary disease.

51 male patients with mild degree chronic airway obstruction underwent detailed evaluation of pulmonary function tests, blood gas analysis and exercise tolerance test before and after a short-term therapy. The patients were randomly assigned to medical therapy alone or to medical and rehabilitative therapy. 23 patients treated with medical and rehabilitative therapy showed a significant decrease of respiratory rate and PaCO2 and a significant increase of TV, FEV 1.0, FEV 0.75 x 40, PaO2, SaO2 and exercise tolerance after a month of therapy. 28 patients treated with medical therapy alone showed a significant increase of VC and FEV 0.75 x 40. These data suggest that rehabilitative therapy is a valid adjunct to medical therapy in the short-term treatment of chronic airway obstruction.

Blood Gas Analysis↗
PubMedDate not supplied

The molecular biology of serotonin receptors. An overview.

Recently, the family of G protein-coupled serotonin (5-hydroxytryptamine[5-HT]) receptors has begun to yield to molecular analysis. The cloning of the 5-HT1C and 5-HT2 receptors has provided a structural basis for the similarities observed in their pharmacologic properties. Furthermore, pharmacologic characterization of the transfected human 5-HT2 receptor has answered two outstanding questions regarding this receptor. First, the few amino acid differences that exist between the human and the rat genes are sufficient to account for the species differences seen in their pharmacologic properties. Second, the single protein encoded by the human 5-HT2 receptor gene is capable of binding both [3H]DOB and [3H]ketanserin. Analysis of the effects of guanine nucleotides provides further evidence that this single protein binds both ligands, that this receptor has high- and low-affinity states, and that these states are partially interconvertible. Furthermore, the close relationship between the adrenergic receptors and the 5-HT1A receptor has been reaffirmed by the recent cloning of a new adrenergic receptor subtype, alpha 2B, by use of the 5-HT1A receptor sequence. Finally, the detailed level of structural information now available on serotonin receptors has yielded valuable information about the ligand binding site and about the possible functional significance of differing rates of evolutionary change in various parts of the gene.

Animals↗