An experimental study on the use of the Hilbert operator as a method of signal preprocessing for the determination of oxygen saturation in retinal vessels

For the non-invasive measurement of the oxygen saturation in human retinal vessels, the light reflected by a vessel and its surroundings is evaluated. Differences in the absorption and scattering properties of the optical media provide so-called vessel profiles, but the central vessel section is often disturbed by a regular reflex. In order to eliminate this reflex, a method based on the Hilbert transform is presented, which can be used for the determination of logarithmic differences between the reflected light on and that beside the vessel. The data for our investigations were produced by simulation of the radiation transport in multi-layered tissue. A linear regression between expected and measured values based on 40 pairs was used for the evaluation of the proposed method. A linear relationship was shown to exist.     

DNA specificity of Escherichia coli deoP1 operator-DeoR repressor recognition

We have studied the importance of the specific DNA sequence of the deo operator site for DeoR repressor binding by introducing symmetrical, single basepair substitutions at all positions in the deo operator and tested the ability of these variants to titrate DeoR in vivo. Our results show that a 16 bp palindromic sequence constitutes the deo operator. Positions outside this palindrome (positions +/- 9, +/- 10) can be changed without any major effect on DeoR binding. Most of the central 6-8 bp of the palindrome (positions +/- 1, +/- 2, +/- 3) can be substituted with other nucleotides with no or only minor effects on DeoR binding, while changes at position +/- 4 and +/- 5 give a more heterogeneous response. Finally, changes at positions +/- 6, +/- 7 and +/- 8 severely disrupt DeoR binding.     

Intra-cavity color selection in ion lasers

The electrooptic effect is utilized to produce a number of types of internal laser color switches. Initial experiments have shown that the primary colored (red, green, blue) lasing lines of the Kr⁺laser can be switched.     

Expression of IGF-II mRNA-binding proteins (IMPs) in gonads and testicular cancer

Insulin-like growth factor-II mRNA-binding proteins 1, 2 and 3 (IMP1, IMP2 and IMP3) belong to a family of RNA-binding proteins implicated in mRNA localization, turnover and translational control. We examined their expression pattern during development of murine and human testis and ovaries. In the mouse, IMPs were expressed in male and female gonadal cells at embryonic day 12.5 (E12.5). From E16.5, IMP1 and IMP3 became restricted to the developing germ cells, whereas IMP2 expression persisted in the interstitial cells. In mature mouse and human ovaries, IMP1, IMP2 and IMP3 were detected in resting and growing oocytes and in the granulosa cells. In testis, IMP1 and IMP3 were found mainly in the spermatogonia, whereas IMP2 was expressed in the immature Leydig cells. Moreover, all three IMPs were detected in human semen. The developmental expression pattern of IMP1 and IMP3 in the human testis prompted us to examine their possible involvement in testicular neoplasia. IMPs were detected primarily in germ-cell neoplasms, including preinvasive testicular carcinoma in situ, classical and spermatocytic seminoma, and nonseminomas, with particularly high expression in undifferentiated embryonal carcinoma. The relative expression of IMP1, IMP2 and IMP3 varied among tumor types and only IMP1 was detected in all carcinoma in situ cells. Thus IMPs, and in particular IMP1, may be useful auxiliary markers of testicular neoplasia.     

Reconstruction of spatially inhomogeneous dielectric tensors through optical tomography

A method to reconstruct weakly anisotropic inhomogeneous dielectric tensors inside a transparent medium is proposed. The mathematical theory of integral geometry is cast into a workable framework that allows the full determination of dielectric tensor fields by scalar Radon inversions of the polarization transformation data obtained from six planar tomographic scanning cycles. Furthermore, a careful derivation of the usual equations of integrated photoelasticity in terms of heuristic length scales of the material inhomogeneity and anisotropy is provided, resulting in a self-contained account about the reconstruction of arbitrary three-dimensional, weakly anisotropic dielectric tensor fields.     

Radioimmunoassay of 8-arginine-vasopressin (antidiuretic hormone) in human plasma

A radioimmunoassay for 8-arginine-vasopressin (AVP) measurement in human plasma has been developed and evaluated, using a commercial preparation of an antibody of AVP. Detection limit of the assay was 0.4 pg. A simple acetone extraction procedure gave a recovery of 65% of added [125I]AVP. The overall sensitivity in the assay was 1.0 pg/ml when 2 ml plasma samples were extracted. The antigenic sites of the employed antibody seemed to be a combination of amino acid residues in the tripeptide tail and the pentapeptide ring. This can explain that the antibody was almost completely insensitive to chemically or enzymatically degraded AVP. The inter-assay coefficient of variation for the control plasma pools averaged 17%. A good correlation to plasma osmolalities above 290 has been found. AVP level in recumbent subjects (n = 8) with plasma osmolalities in the normal range was 2.8 +/- 1.0 pg/ml (mean +/- SD) and in ambulatory subjects (n = 10) on ad lib. water intake 4.5 +/- 1.9 pg/ml (mean /+- SD).