Immunocytochemical localization of the neuronal growth associated protein GAP-43 revealed a dense axonal plexus throughout the neurointermediate lobe of the rat pituitary. These axons were fine, presumably monoaminergic fibers, whereas magnocellular neurosecretory axons did not appear to contain detectable GAP-43. These experiments also revealed the presence of an extensive nerve plexus within the anterior lobe. Fine beaded fibers were present throughout the parenchyma of the anterior lobe, and punctate staining suggestive of nerve terminals was seen surrounding numerous endocrine cells. Nerve fibers did not appear to cross directly between the intermediate and anterior lobes, but rather entered the anterior lobe directly from its margins or in association with blood vessels. Preabsorption of antisera with GAP-43 purified from neonatal rat brain completely eliminated immunoreactivity. These findings confirm the existence of a direct innervation of the anterior pituitary of the rat; moreover, the presence of GAP-43 in these fibers suggests that they may be capable of growth and terminal reorganization in the adult animal.
Background
The Siemens Immulite hCG assay detects all major hCG variants in serum. Currently, this assay is only FDA approved for qualitative measurement of hCG in urine.
Methods
Complete validation of the hCG assay in urine was performed on the Siemens Immulite 1000 immunoassay platform. Reference intervals were established for females <55 y, females ≥55 y, and males 20–70 y.
Results
The limit of quantitation was 2.0 IU/l. The Immulite hCG assay was precise for measuring hCG in urine from pregnant patients with intra- and inter-assay imprecision of <11% CV. The assay was linear over a dynamic range of 2–2600 IU/l and 2–3500 IU/l for hCG and hCGβ respectively. The assay was non-linear for hCGβcf. No hook effect was observed at concentrations up to 1,200,000 pmol/l, for hCGβ or hCGβcf. The reference intervals were <2.0 IU/l for males, <2.2 IU/l for females <55 y, and <12.2 IU/l for females ≥55 y.
Conclusion
The Immulite 1000 hCG assay can accurately quantify hCG in urine.
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