Measurement of Optic Nerve Sheath Diameter: Differences between Methods? A Pilot Study.

BACKGROUND: Quantification of the optic nerve sheath diameter is a promising approach for the detection of elevated intracranial pressure. The comparability of current methods is unclear. The objective of this study was to assess the relationship between optic nerve sheath diameter as measured with computed tomography, magnetic resonance tomography and ultrasound in patients without known optic nerve disease or increased intracranial pressure. PATIENTS AND METHODS: 15 patients (60.8 [years]±16.73 SD; 7 female) with paranasal sinus pathology in whom computed tomography and magnetic resonance imaging were performed underwent optic nerve sheath diameter measurements by ultrasound, as well as an ophthalmological examination. Ultrasound-, computed tomography- and magnetic resonance imaging-derived maximal optic nerve sheath diameter values 3 mm behind the globe were compared. RESULTS: Optic nerve sheath diameter measured (n=30) by ultrasound (mean 6.2 [mm]±0.84 SD) was significantly (p<0.01) higher than optic nerve sheath diameter in computed tomography (5.2±1.11) or magnetic resonance imaging (5.3±1.14). There was no significant (p=0.24) difference between optic nerve sheath diameter measured in computed tomography and magnetic resonance tomography. CONCLUSIONS: The comparability of optic nerve sheath diameter measurements in patients without known optic nerve disease and assumed normal intracranial pressure appears to be given between computed tomography and magnetic resonance tomography, while comparability between ultrasound and computed tomography or magnetic resonance tomography seems to be less reliable.

Natural and sexual selection against immigrants maintains differentiation among micro-allopatric populations.

Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence lead to speciation. But what mechanisms contribute to reproductive isolation among diverging populations? We tested for natural and sexual selection against immigrants in a fish species inhabiting (and adapting to) nonsulphidic surface habitats, sulphidic surface habitats and a sulphidic cave. Gene flow is strong among sample sites situated within the same habitat type, but low among divergent habitat types. Our results indicate that females of both sulphidic populations discriminate against immigrant males during mate choice. Furthermore, using reciprocal translocation experiments, we document natural selection against migrants between nonsulphidic and sulphidic habitats, whereas migrants between sulphidic cave and surface habitats did not exhibit increased mortality within the same time period. Consequently, both natural and sexual selection may contribute to isolation among parapatric populations, and selection against immigrants may be a powerful mechanism facilitating speciation among locally adapted populations even over very small spatial distances.

Serum ACTH levels in patients with polycystic ovarian disease.

Serum adrenocorticotrophic hormone levels were assayed in 8 patients with polycystic ovaries and a similar number of control subjects. Serum ACTH concentrations were normal in 6 patients and marginally elevated in 1. Investigations of markedly elevated readings in another patient showed this to be due to an interfering factor rather than the ACTH molecule itself.

The effect of seminal plasma on gonadotrophin secretion by sheep pituitary cells in culture.

We tested the effect of seminal plasma fractions of pooled normozoospermic and azoospermic seminal plasma on secretion of LH by sheep pituitary cells in culture. From these experiments we conclude that there is activity in seminal plasma (molecular mass 10.000-80.000) which inhibits LH secretion. This activity is not steroid-mediated and is absent in azoospermic seminal plasma. These data support our thesis that LH secretion is not only controlled by testosterone but also by spermatogenesis per se.

A radioimmunoassay specific for [Gln8]LH-RH: application in the confirmation of the structure of chicken hypothalamic luteinizing hormone-releasing hormone.

In the first report on the chemical structure of a nonmammalian LH-RH, chicken hypothalamic LH-RH was demonstrated to be [Gln8]LH-RH [2-4]. However, these studies and subsequent reports [7,8] did not totally exclude the possibility of a reverse sequence of the two amino acids Leu-Gln. In view of the recently described structure of salmon brain LH-RH as [Trp7,Leu8]LH-RH [9], we undertook to confirm our earlier conclusion that chicken LH-RH is [Gln8]LH-RH and not [Gln7, Leu8]LH-RH. The immunologic, chromatographic and biological properties of natural chicken hypothalamic LH-RH were compared with those of the two synthetic peptides, [Gln8]LH-RH and [Gln7,Leu8]LH-RH. A radioimmunoassay highly specific for [Gln8]LH-RH was developed. Natural chicken LH-RH cross-reacted fully with the antiserum which requires the COOH-terminal Gln8 to Gly10-NH2 for binding, while [Gln7,Leu8]LH-RH showed less than 0.1% cross-reaction. On a high resolution reverse phase high performance liquid chromatography system, natural chicken LH-RH co-eluted with [Gln8]LH-RH and was well separated from [Gln7,Leu8]LH-RH. In a chicken anterior pituitary cell bioassay, natural chicken LH-RH and [Gln8]LH-RH were equipotent in stimulating luteinizing hormone release, while the relative potency of [Gln7,Leu8]LH-RH was 4.4%. These data, in particular the use of a specific [Gln8]LH-RH antiserum, provide conclusive evidence that chicken LH-RH is [Gln8]LH-RH.

Comparative structure-activity studies on mammalian [Arg8] LH-RH and chicken [Gln8] LH-RH by fluorimetric titration.

Fluorimetric titrations of mammalian [Arg8] LH-RH, chicken [Gln8] LH-RH and an analogue [Lys8] LH-RH revealed pK values of 5.80, 6.22 and 6.01 for His2, and 9.65, 9.88 and 9.88 for Tyr5. The titration ranges for His2 were 1.72, 2.03 and 1.71 while the range for Tyr5 was rather similar (approximately 1.7) for all three peptides. Biological activity and receptor binding in the mammalian system for chicken LH-RH was 1% relative to mammalian LH-RH while [Lys8] LH-RH had a relative activity of approximately 10%. In contrast, mammalian and chicken LH-RH were equipotent in stimulating LH release from chicken pituitary cells. The results indicate differences in the receptors related to the conformations of LH-RH and position 8-substituted analogues.

A radioimmunoassay for 7 alpha-hydroxy dehydroepiandrosterone in human plasma.

A radioimmunoassay for plasma 3 beta, 7 alpha-dihydroxy-5-androsten-17-one (7 alpha-hydroxy DHA) has been developed using anti-sera raised against 3 beta, 7 alpha-dihydroxy-5-androstene-17 beta-carboxyl-bovine serum albumin conjugate and [1, 2 (n) - 3H] 7 alpha-hydroxy DHA as the radioligand. Significant cross reactivity was found with 3 beta, 7 alpha-dihydroxy-5-pregnen-20-one (44%), 3 beta, 7 beta-dihydroxy-5-androsten-17-one (6%), 3 beta, 6 beta-dihydroxy-4-androsten-17-one (2.5%), 3 beta-hydroxy-5-androsten-17-one (DHA, 2%), 3 beta, 7 beta-dihydroxy-5-pregnen-20-one (2%) and 7 alpha-hydroxy-4-androstene-3, 20-dione (1%). 7 alpha-Hydroxy DHA was extracted from plasma and separated from cross-reacting factors using alumina micro-columns. The separation of bound and free steroid was achieved using dextran-coated charcoal. The concentration of 7 alpha-hydroxy DHA in the plasma of breast cancer patients was significantly lower than the concentrations in the plasma of normal women, hospitalized women suffering from non-endocrine diseases and patients with benign breast disease. The decrease in the concentration of 7 alpha-hydroxy DHA in the plasma of pregnant women was not significant.

The in vitro synthesis of 7-hydroxy dehydroepiandrosterone by human mammary tissues.

Normal and tumorous human mammary tissues were incubated in vitro with [7alpha-3H] dehydroepiandrosterone and [7alpha-3H] dehydroepiandrosterone sulphate. Tritium-labelled 7alpha-hydroxy dehydroepiandrosterone was identified as a principal metabolite from four of the five studies with normal tissue and all seven studies with tumorous tissue.