Several quinolone and fluoroquinolone haptens have been used to raise polyclonal antibodies exhibiting both specific and generic properties for these classes of antimicrobial compounds. The antisera have been assessed in rapid enzyme immunoassays (ELISAs) designed to exploit the specificities obtained. A direct generic ELISA for both the quinolones and fluoroquinolones has been developed that uses the cross-reactivity of an antibody raised against norfloxacin (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid) linked to ovalbumin via a secondary amine group on the piperazinyl moiety to detect nine different drugs in these classes. Specific ELISAs to ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid), enrofloxacin (1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid), flumequin (9-fluoro-6,7-dihydro-5-methyl-1-oxo-1H,5H-benzo(ij)quinolizine-2-carboxylic acid) and nalidixic acid (1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxylic acid) have also been developed with a high degree of specificity to the individual compounds. The assays measure drug residues in bovine milk and ovine kidney with an interassay relative standard deviation (s(r)) of 10.5% or less and intra-assay s(r) of 11.2% or less. Sensitivity is less than 4 microg x kg(-1) for both the generic and specific assays for all but one of the compounds tested. (Pipemidic acid (8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acid) is detectable at 6 microg x kg(-1) in kidney.)
The growth of two human prolactin-secreting cell lines developed in our laboratory has been investigated in response to a number of factors. Oestrogen stimulated the synthesis of DNA and protein and increased prolactin secretion. Dexamethasone had the opposite effect to oestrogen. In the presence of serum, epidermal growth factor (EGF) inhibited cell growth at concentrations of 5 ng/ml. Known secretagogues of prolactin (vasoactive intestinal peptide (VIP), TRH, bombesin and neurotensin) were investigated for their action on cell growth but only VIP had a stimulatory effect. Two preparations of fibroblast growth factor (FGF) were studied. One form, derived from bovine pituitary glands, stimulated human pituitary cell growth. In contrast, another FGF, of the basic type (rFGF), was inhibitory to cell growth, increasing the time for cell doubling from 30 to 72 h. This inhibitory effect of rFGF was modified but not abolished by serum, oestradiol, platelet-derived growth factor or EGF. We conclude that bovine pituitary contains at least two fibroblast growth factors, both of which stimulate fibroblast cell growth, but one stimulates and the other inhibits human pituitary tumour cell growth.
Treatment with a high dose of oestradiol for 6 months caused hyperprolactinaemia and pituitary hyperplasia in female Wistar-Furth rats. Changes in the vasoactive intestinal peptide (VIP) and dopamine content of the hypothalamus and pituitary were also found. The hypothalamic dopamine concentration was only slightly reduced and, although the concentration of dopamine in the pituitary was less in treated animals, the total pituitary content was increased. The concentration of VIP in the pituitary was increased by oestradiol treatment but decreased in the non-median eminence hypothalamus. In the median eminence the VIP content was increased by oestradiol treatment and the amount present correlated positively and significantly with pituitary wet weight in animals treated with both oestradiol and fluphenazine. In Fischer 344 rats, oestradiol produced greater incremental changes in pituitary wet weight and plasma concentrations of prolactin than in Wistar controls and the increase in the pituitary concentration of VIP was five times greater. Although peptide turnover has not been measured, these results suggest that oestradiol, as well as having a direct action, stimulates pituitary lactotrophs by increasing pituitary concentrations of VIP.
Immunoreactive (ir) basic fibroblast growth factor (FGF) has been measured in normal human pituitary glands and in 41 pituitary tumours of various types using a radioimmunoassay. Normal pituitary glands contained ir basic FGF ranging from 29.4 to 355 fmol/mg wet weight whereas 87.5% of pituitary tumours contained amounts of the growth factor which were less than normal. There was no relationship between the type of tumour and the FGF content. Normal and tumorous pituitary FGF had an affinity for heparin which was similar to that of basic FGF. Gel column chromatography revealed that the pituitary ir FGF was present mainly as high molecular weight forms, with only a small proportion as the basic 146 amino-acid peptide. Because of our previous observation that basic FGF inhibits the growth of human pituitary tumour cells, it is suggested that the reduction in basic FGF of many pituitary tumours may favour the stimulation of pituitary growth.
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