Tamm plasmons in metal/nanoporous GaN distributed Bragg reflector cavities for active and passive optoelectronics.

We theoretically and experimentally investigate Tamm plasmon (TP) modes in a metal/semiconductor distributed Bragg reflector (DBR) interface. A thin Ag (silver) layer with a thickness (55 nm from simulation) that is optimized to guarantee a low reflectivity at the resonance was deposited on nanoporous GaN DBRs fabricated using electrochemical (EC) etching on freestanding semipolar (2021¯) GaN substrates. The reflectivity spectra of the DBRs are compared before and after the Ag deposition and with that of a blanket Ag layer deposited on GaN. The experimental results indicate the presence of a TP mode at ∼ 454 nm on the structure after the Ag deposition, which is also supported by theoretical calculations using a transfer-matrix algorithm. The results from mode dispersion with energy-momentum reflectance spectroscopy measurements also support the presence of a TP mode at the metal-nanoporous GaN DBR interface. An active medium can also be accommodated within the mode for optoelectronics and photonics. Moreover, the simulation results predict a sensitivity of the TP mode wavelength to the ambient (∼ 4-7 nm shift when changing the ambient within the pores from air with n = 1 to isopropanol n = 1.3), suggesting an application of the nanoporous GaN-based TP structure for optical sensing.

All-solid-state VUV frequency comb at 160 nm using high-harmonic generation in nonlinear femtosecond enhancement cavity.

We realized a solid-state-based vacuum ultraviolet frequency comb by harmonics generation in an external enhancement cavity. Optical conversions were so far reported by only using gaseous media. We present a theory that allows the most suited solid generation medium to be selected for specific target harmonics by adapting the material's bandgap. We experimentally use a thin AlN film grown on a sapphire substrate to realize a compact frequency comb high-harmonic source in the Deep Ultraviolet (DUV) / Vacuum Ultraviolet (VUV) spectral range. By extending our earlier VUV source [Opt. Express26, 21900 (2018)] with the enhancement cavity, a sub-Watt level Ti:sapphire femtosecond frequency comb is enhanced to 24 W stored average power, its 3rd, 5th, and 7th harmonics are generated, and the targeted 5th harmonic's power at 160 nm increased by two orders of magnitude. The emerging nonlinear effects in the solid medium, together with suitable intra-cavity dispersion management, support optimal enhancement and stable locking. To demonstrate the realized frequency comb's spectroscopic ability, we report on the beat measurement between the 3rd harmonic beam and a 266 nm CW laser reaching about 1 MHz accuracy.

Redox properties and electron transfer in a triarylamine-substituted HS-Co2+/LS-Co3+ redox couple.

A new tridentate phenanthroline-pyridyl-based ligand 1 containing a redox active Tara (triaryl amine) unit has been developed (1 = 4-((6-(1,10-phenanthrolin-2-yl)pyridin-2-yl)oxy)-N,N-di-p-tolylaniline). The complex [Co2+(1)2](ClO4/BF4)2 was prepared and the order of the oxidation steps was analysed by cyclic voltammetry and EPR/UV-vis-NIR spectroelectrochemistry. Oxidation of [Co2+(1)2]2+ to [Co3+(1+)2]5+ proceeds in two steps. The first step is the Co2+/3+ centred oxidation to [Co3+(1)2]3+ (E°'(M2+/3+) = 284 mV vs. Fc/Fc+) followed by oxidation of the Tara0/+ centres (E°'(Tara) = 531 mV). Both kinds of oxidation processes were independently investigated in the analogous complexes [Zn(1)2](ClO4)2 and [Co(2)2](BF4)2 allowing an assignment of changes in the electronic spectra to the redox states (2 = 2-(6-phenoxypyridin-2-yl)-1,10-phenanthroline). Although spectroelectrochemistry did not indicate substantial coupling between the redox centres the Tara unit is an efficient mediator for the self-exchange in the [Co2+/3+(1)2]2+/3+ couple. The electron transfer by self-exchange in [Co2+/3+(1)2]2+/3+ was further investigated by variable temperature (VT) 1H NMR spectroscopy. In addition, the resonances found in the paramagnetic proton NMR spectra were assigned by using COSY, T1 and EXSY measurements in combination with the Co-N distances obtained from X-ray analysis. [Co(1)2]2+ is found in the HS state. In contrast, the Fe2+ species [Fe(1)2](ClO4)2 is a spincrossover system. The SCO was analysed in solution by VT 1H NMR and VT/vis spectroscopy.

(1)H NMR spectroscopic elucidation in solution of the kinetics and thermodynamics of spin crossover for an exceptionally robust Fe(2+) complex.

A series of Fe(2+) spin crossover (SCO) complexes [Fe(5/6)](2+) employing hexadentate ligands (5/6) with cis/trans-1,2-diamino cyclohexanes (4) as central building blocks were synthesised. The ligands were obtained by reductive amination of 4 with 2,2'-bipyridyl-6-carbaldehyde or 1,10-phenanthroline-2-carbaldehyde 3. The chelating effect and the rigid structure of the ligands 5/6 lead to exceptionally robust Fe(2+) and Zn(2+) complexes conserving their structure even in coordinating solvents like dmso at high temperatures. Their solution behavior was investigated using variable temperature (VT) (1)H NMR spectroscopy and VT Vis spectroscopy. SCO behavior was found for all Fe(2+) complexes in this series centred around and far above room temperature. For the first time we have demonstrated that the thermodynamics as well as kinetics for SCO can be deduced by using VT (1)H NMR spectroscopy. An alternative scheme using a linear correction term C(1) to model chemical shifts for Fe(2+) SCO complexes is presented. The rate constant for the SCO of [Fe(rac-trans-5)](2+) obtained by VT (1)H NMR was validated by Laser Flash Photolysis (LFP), with excellent agreement (1/(kHL + kLH) = 33.7/35.8 ns for NMR/LFP). The solvent dependence of the transition temperature T1/2 and the solvatochromism of complex [Fe(rac-trans-5)](2+) were ascribed to hydrogen bond formation of the secondary amine to the solvent. Enantiomerically pure complexes can be prepared starting with R,R- or S,S-1,2-diaminocyclohexane (R,R-trans-4 or S,S-trans-4). The high robustness of the complexes reduces a possible ligand scrambling and allows preparation of quasiracemic crystals of [Zn(R,R-5)][Fe(S,S-5)](ClO4)4·(CH3CN) composed of a 1 : 1 mixture of the Zn and Fe complexes with inverse chirality.

Oligoclonal restriction of antiviral immunoreaction in oligoclonal band-negative MS patients.

OBJECTIVES: Presence of oligoclonal bands (OCB) in cerebrospinal fluid (CSF) is a diagnostic hallmark of multiple sclerosis (MS). However, up to 10% of patients were OCB negative in routine laboratory tests. The aim of this study was to determine whether there is at least an oligoclonal restriction of intrathecal antibody synthesis against measles, rubella and/or varicella zoster virus (MRZ-specific OCB) in CSF from oligoclonal bands-negative patients with MS. METHODS: CSF and serum samples from 17 well-defined OCB-negative patients with MS were analysed for MRZ-specific OCB. We performed isoelectric focusing (IEF) combined with affinity blotting using viral antigens, detection with a highly sensitive chemiluminescence technique and recording with X-ray films. Controls included 18 OCB-positive patients with MS and 11 patients with pseudotumor cerebri (PTC). RESULTS: Exclusive or predominant MRZ-specific OCB in CSF against at least one virus species were present in 8 of 17 patients with MS (47.1%; P = 0.0422), suggesting an oligoclonal intrathecal immune response, although OCB of total IgG were absent. Only a very weak oligoclonal reaction against varicella zoster virus in CSF from one of the PTC controls was detectable. Thirteen of 18 (72.2%; P = 0.0013) OCB-positive patients with MS showed also MRZ-specific oligoclonal bands against at least 1 neurotropic virus in CSF. CONCLUSIONS: MRZ-specific OCB argue for existence of a chronic intrathecal immune reaction also in routine laboratory-OCB-negative patients with MS. This phenomenon reflects oligoclonal restriction of the humoral immunoreaction as well as polyspecific intrathecal antibody synthesis, which are both characteristics in the chronic inflammatory process of MS.

Metal-metal interaction in Fischer carbene complexes: a study of ferrocenyl and biferrocenyl tungsten alkylidene complexes.

A series of ferrocenyl (Fc = ferrocenyl; fc = ferrocen-1,1'-diyl) and biferrocenyl (Bfc = 1',1″-biferrocenyl; bfc = 1',1″-biferrocen-1,1‴-diyl) mono- and biscarbene tungsten(0) complexes of the type [(CO)5W═C(OMe)R] (1, R = Fc; 3, R = Bfc) and [(CO)5W═C(OMe)-R'-(OMe)C═W(CO)5] (2, R' = fc; 4, R' = bfc) were synthesized according to the classical synthetic methodology by reacting W(CO)6 with LiR (R = Fc, fc, bfc), followed by a subsequent alkylation using methyl trifluoromethanesulfonate. Electrochemical investigations were carried out on these complexes to get a closer insight into the electronic properties of 1-4. The ferrocenyl and biferrocenyl moieties in 1-4 show reversible one-electron redox events. It was further found that the Fischer carbene unit is reducible in an electrochemical one-electron transfer process. For the tungsten carbonyl moieties, irreversible oxidation processes were found. In addition, charge transfer studies were performed on 1-4 using in situ UV-vis-NIR and infrared spectroelectrochemical techniques. During the UV-vis-NIR investigations, typical low energy transitions for the mixed-valent biferrocenyl unit were found. A further observed high energy NIR absorption is attributed to a metal-metal charge transfer transition between the tungsten carbonyl fragment and the ferrocenyl/biferrocenyl group in the corresponding oxidized states, which can be described as class II systems according to Robin and Day. This assignment was verified by infrared spectroelectrochemical studies. The electrochemical investigations are supported by density functional theory calculations. The structural properties of 1-4 in the solid state were investigated by single-crystal X-ray diffraction studies showing no substituent effects on bond lengths and angles. The biferrocenyl derivatives exhibit syn-conformation of the ferrocenyl and carbene building blocks.

Qualitative and quantitative evidence of anti-glutamic acid decarboxylase-specific intrathecal antibody synthesis in patients with stiff person syndrome.

BACKGROUND: The stiff person syndrome (SPS) is a CNS disorder of putative autoimmune aetiology, which is clinically characterized by severe rigidity and spasms. In most cases, SPS is associated with serum antibodies against glutamic acid decarboxylase (GAD-Ab). Recent studies suggested that GAD-Ab might be directly involved in the pathogenesis of SPS. Further support for this hypothesis would come from studies providing qualitative evidence for the presence of GAD-Ab-producing B cell clones within the CNS of patients with SPS. OBJECTIVE AND METHODS: To address that issue, we (i) analysed paired cerebrospinal fluid (CSF) and serum samples from ten GAD-Ab positive patients with SPS and controls by an antigen-driven affinity blotting technique for the presence of GAD-specific oligoclonal IgG bands (OCBs) in the CSF, and (ii) examined the immunoreactive pattern of CSF and serum IgG to recombinant GAD by immunoblotting. To confirm our results quantitatively, we (iii) assessed anti-GAD antibody reactivity in CSF and serum using ELISA and evaluated the GAD-specific antibody index. RESULTS: GAD-specific oligoclonal bands exclusively or predominately in CSF compared to the corresponding serum were detected in 10/10 patients with GAD-positive SPS but in none of the controls. Immunoblotting revealed stronger staining in the CSF, suggestive of intrathecal IgG synthesis, in 7/10 patients upon visual inspection, and in 8/10 patients upon densitometric analysis. A positive GAD-specific antibody index was found in 9/10 patients. CONCLUSIONS: Here we demonstrate for the first time that IgG OCBs in SPS bind GAD. Our findings contribute to the ongoing discussion on whether the autoimmune process against GAD is involved in the pathogenesis of SPS by indicating that anti-GAD-Ab is produced by B cell clones within the CNS.

Characterization of individual threading dislocations in GaN using ballistic electron emission microscopy.

Threading dislocations (TDs) of molecular beam epitaxy grown GaN film were studied with ultrahigh vacuum ballistic electron emission microscopy in order to quantify any fixed negative charge at identifiable TDs, with approximately 3 nm spatial and approximately 10 meV local barrier resolution. In contrast to several prior studies, we find no indication of fixed negative dislocation charge at specific TD structures, with a conservative upper limit of approximately 0.25 e(-) per c-axis unit cell. We do observe evidence of positive surface charge at TDs and at GaN step edges, which may be due to local piezoelectric fields.

Growth factors in combination, but not individually, rescue rd mouse photoreceptors in organ culture.

The rd mouse retina is an animal model for human retinal dystrophy in which the rod photoreceptors undergo apoptosis during the first 4 weeks in vivo or in organ culture. We have examined the effect of different families of trophic factors on the survival of rd mouse photoreceptors in organ culture. Retinas were harvested from rd mice at postnatal day 2 and grown in organ culture for 27 days in vitro (DIV) in DMEM with 10% fetal calf serum. Ciliary neurotrophic factor (CNTF), brain-derived neurotrophic factor (BDNF), fibroblast growth factor-2 (FGF2), glial cell line-derived neurotrophic factor (GDNF), neurturin, and persephon were added individually or in combination to the medium at a dose of 50 ng/ml or less. CNTF + BDNF in combination resulted in photoreceptor survival comparable to wild-type retinas after 27 DIV. CNTF + FGF2 or CNTF + GDNF produced a partial prevention of photoreceptor death. Photoreceptor degeneration was not blocked by any of the trophic factors added individually. A significant increase in photoreceptor survival was seen with forskolin added to CNTF, but not to BDNF, FGF2, or GDNF. These results demonstrate that trophic factors promote photoreceptor survival through a synergistic interaction. Increased understanding of receptor interactions and signaling pathways may lead to a potential therapeutic role for combinatorial trophic factors in treatment of photoreceptor dystrophies.

A reliable method for organ culture of neonatal mouse retina with long-term survival.

Organ culture systems of the central nervous system have proven to be useful tools for the study of development, differentiation, and degeneration. Some studies have been limited by the inability to maintain the cultures over an extended period. Here we describe an organ culture technique for the mouse retina. This method uses commercially available supplies and reproducible procedures to maintain healthy retinas with normal architecture for 4 weeks in vitro. The system is amenable to quantitative analysis. It can be used with both normal and retinal degeneration (rd) retinas to study of the role of various factors in photoreceptor degeneration in retinal cell fate determination and development.

A prospective randomized trial of prevention measures in patients at high risk for contrast nephropathy: results of the P.R.I.N.C.E. Study. Prevention of Radiocontrast Induced Nephropathy Clinical Evaluation.

OBJECTIVES: This study was done to test the hypothesis that a forced diuresis with maintenance of intravascular volume after contrast exposure would reduce the rate of contrast-induced renal injury. BACKGROUND: We have previously shown a graded relationship with the degree of postprocedure renal failure and the probability of in-hospital death in patients undergoing percutaneous coronary intervention. Earlier studies of singular prevention strategies (atrial natriuretic factor, loop diuretics, dopamine, mannitol) have shown no clear benefit across a spectrum of patients at risk. METHODS: A prospective, randomized, controlled, single-blind trial was conducted where 98 participants were randomized to forced diuresis with intravenous crystalloid, furosemide, mannitol (if pulmonary capillary wedge pressure <20 mm Hg), and low-dose dopamine (n = 43) versus intravenous crystalloid and matching placebos (n = 55). RESULTS: The groups were similar with respect to baseline serum creatinine (2.44+/-0.80 and 2.55+/-0.91 mg/dl), age, weight, diabetic status, left ventricular function, degree of prehydration, contrast volume and ionicity, and extent of peripheral vascular disease. The forced diuresis resulted in higher urine flow rate (163.26+/-54.47 vs. 122.57+/-54.27 ml/h) over the 24 h after contrast exposure (p = 0.001). Two participants in the experimental arm versus five in the control arm required dialysis, with all seven cases having measured flow rates <145 ml/h in the 24 h after the procedure. The mean individual change in serum creatinine at 48 h, the primary end point, was 0.48+/-0.86 versus 0.51+/-0.87, in the experimental and control arms, respectively, p = 0.87. There were no differences in the rates of renal failure across six definitions of renal failure by intent-to-treat analysis. However, in all participants combined, the rise in serum creatinine was related to the degree of induced diuresis after controlling for baseline renal function, r = -0.36, p = 0.005. The rates of renal failure in those with urine flow rates greater than 150 ml/h in the postprocedure period were significantly lower, 8/37 (21.6%) versus 28/61 (45.9%), p = 0.03. CONCLUSIONS: Forced diuresis with intravenous crystalloid, furosemide, and mannitol if hemodynamics permit, beginning at the start of angiography provides a modest benefit against contrast-induced nephropathy provided a high urine flow rate can be achieved.

Comparison of hexadecylphosphocholine with fish oil as an antitumor agent.

Hexadecylphosphocholine (HePC) reduced the growth of the human mammary tumor, MX-1, in the athymic nude mouse similar to the fish oil, MaxEPA. When used together, HePC and MaxEPA were additive towards reducing tumor growth. An unsaturated alkylphosphocholine mixture, ShisoPC, was not as effective as HePC in reducing tumor growth. MaxEPA reduced tumor PGE2 levels greater than 90%, while HePC and the ShisoPC only reduced tumor PGE2 40-60% with HePC being slightly better than ShisoPC. MaxEPA markedly increased the cellular omega 3 fatty acids and decreased 20:4 omega 6, the substrate for PGE2. HePC did not alter the tumor fatty acid composition, but it significantly lowered the total fatty acid concentration of the tumor by about 47%. In addition, phosphatidylcholine and sphingomyelin decreased in tumors from animals treated with HePC, and alterations in other phospholipids also were noted. These data suggest that different mechanisms exist for HePC and fish oil in reducing tumor growth.

Progression of cochlear and retinal degeneration in the tubby (rd5) mouse.

Mice homozygous for a defect of the tub (rd5) gene exhibit cochlear and retinal degeneration combined with obesity, and resemble certain human autosomal recessive sensory deficit syndromes. To establish the progressive nature of sensory cell loss associated with the tub gene, and to differentiate tub-related losses from those associated with the C57 background on which tub arose, we evaluated cochleas and retinas from tub/tub, tub/+, and +/+ mice, aged 2 weeks to 1 year by light and electron microscopy. Cochleas from mice of all three genotypes show progressive inner (IHC) and outer hair cell (OHC) loss. Relative to tub/+ and +/+ animals, however, tub homozygotes show accelerated OHC loss, affecting the extreme cochlear base (hook region) by 1 month, and the apex by 6 months. IHC loss in tub/tub animals is accelerated in the basal half of the cochlea, affecting the hook region by 6 months. Spiral ganglion cell losses were observed only in tub/tub mice, and only in the cochlear base. Retinas of tub/tub mice are abnormal at maturity, exhibiting shortened photoreceptor outer segments by 2 weeks, and progressive photoreceptor loss thereafter. Because the tub mutation causes degeneration of sensory cells in the ear and eye but has no other neurological effects, tubby mice hold unique promise for the study of human syndromic sensory loss.

Age-related distribution of cones and ON-bipolar cells in the rd mouse retina.

PURPOSE: Retinal dystrophic (rd) mice lose most of their rod photoreceptors within the first three weeks after birth. We determined the age-related distribution of peanut agglutinin lectin (PNA)-labeled cones during the first 12 months of age. We also investigated whether the density of ON-bipolar cells expressing L7 protein was affected by their loss of photoreceptor inputs. METHODS: rd mice were selected from a transgenic strain which expresses an L7-beta-galactosidase fusion gene localized to ON-bipolar cells. Cones were stained with PNA and ON-bipolar cells with bluo-gal (halogenated indolyl-beta-D-galactoside). Retinas were flat-mounted and observed at 1, 2, 3, 6 and 12 months of age. RESULTS: PNA-labeled cones are distributed unevenly across the retina at 1 month postnatal. Their concentration decreases first in the central and far peripheral retina, leaving a ring of labeled cells in the midperipheral region. At 3 months, a larger patch of cones remains in the supero-temporal midperipheral region and a smaller patch in the infero-nasal retina. By 6 months, few cones remain in the infero-nasal retina; by 1 year approximately 100 cones remain in the entire retina, localized to the superior midperipheral region. ON-bipolar cells appear evenly distributed at 1 month. By 2-3 months, relatively more bluo-gal staining is seen in the midperipheral regions underlying dense cone populations. At 6-12 months, bluo-gal label is distributed in a spotty pattern with little or no staining seen in areas of apparent neovascularization. CONCLUSIONS: (1) PNA-labeling of cones in the rd retina deteriorates in a distinct spatial pattern with the longest cone survival in the midperipheral superior retina. (2) ON-bipolar cells are more densely labeled in regions of high cone density during the early months of cone degeneration and, in later stages, show relative decreases in regions of apparent neovascularization.

Effects of omega 3 fatty acids on receptor tyrosine kinase and PLC activities in EMT6 cells.

The effects of omega 3 fatty acids and epidermal growth factor (EGF) on the activity of receptor tyrosine kinase (RTK) and phospholipase C (phosphatidylinositol (PI)-specific PLC) were examined in EMT6 cells. The non-omega 3 treated, non-EGF stimulated cells served as controls. Treatment of the EMT6 cells with omega 3 fatty acids resulted in a 62% increase in RTK activity and a 67% increase in PI-specific PLC activity. When EGF was added to incubations for RTK activity, it stimulated the RTK activity 40% in the control cells and 130% in the omega 3-treated cells. When EGF was added to incubations for PI-specific PLC activity, a 54% increase in PI-specific PLC activity was observed in control cells and a 94% increase in the omega 3-treated cells. Thus, treating EMT6 cells with omega 3 fatty acids seems to increase RTK activity and PI-specific PLC activity to a similar extent, but has differential effects on the ability of these enzyme activities to be stimulated by EGF.

[Avian yolk antibodies in diagnosis and research]. / Aviäre Dotter-Antikörper in Diagnostik und Forschung.

Hens were immunized with bacterial polysaccharide (alginate), Hepatitis B surface antigen (HBsAg), and potato viruses (PVA, PVS, PVM, PVX, and PVY). The antibodies were isolated noninvasively from the yolks of laid eggs. The purified yolk immunoglobulins (IgY) were tested in an array of various assays and diagnostic techniques. The methods employed were precipitation reactions, immun-electrophoresis, ELISA (after biotinylation of IgY), immuno-gold electron microscopy, and western and immuno blotting. Some of these methods had to be modified according to the special requirements of avian antibodies. The special handling of this animal system is described in regard to antibody production. The results demonstrate that IgY derived from hens can replace IgG produced by traditional methods in mammals. The advantages of this alternate animal system are emphasized in respect to animal care, high productivity, and special suitability of avian antibodies for certain diagnostic purposes.

4-Oxoretinol, a new natural ligand and transactivator of the retinoic acid receptors.

All-trans-retinoic acid (at-RA) induces cell differentiation in a wide variety of cell types, including F9 embryonic teratocarcinoma cells, and can influence axial pattern formation during embryonic development. We now identify a novel retinoid synthetic pathway in differentiating F9 cells that results in the intracellular production of 4-oxoretinol (4-oxo-ROL) from retinol (vitamin A). Approximately 10-15% of the total retinol in the culture is metabolized to 4-hydroxyretinol and 4-oxo-ROL by the at-RA-treated, differentiating F9 cells over an 18-hr period, but no detectable metabolism of all-trans-retinol to at-RA or 9-cis-retinoic acid is observed in these cells. Remarkably, we show that 4-oxo-ROL can bind and activate transcription of the retinoic acid receptors whereas all-trans-retinol shows neither activity. Low doses of 4-oxo-ROL (e.g., 10(-9) or 10(-10 M) can activate the retinoic acid receptors even though, unlike at-RA, 4-oxo-ROL does not contain an acid moiety at the carbon 15 position. 4-oxo-ROL does not bind or transcriptionally activate the retinoid X receptors. Treatment of F9 cells with 4-oxo-ROL induces differentiation without conversion to the acid and 4-oxo-ROL is active in causing axial truncation when administered to Xenopus embryos at the blastula stage. Thus, 4-oxo-ROL is a natural, biologically active retinoid that is present in differentiated F9 cells. Our data suggest that 4-oxo-ROL may be a novel signaling molecule and regulator of cell differentiation.

[Comparison of different methods for the diagnosis of freemartinism--blood group serology, cytology and polymerase chain reaction]. / Vergleich verschiedener Methoden zur Diagnose des bovinen Freemartinismus--Blutgruppenserologie, Zytologie und Polymerase-Ketten-Reaktion.

The percentage of freemartins among blood samples tested by chromosome analysis amounted to 83.9%, by blood group serologie 71.4%. 126 blood samples have been tested by blood group serology and PCR. Employing blood group serology, 71.3% and using PCR with BOV97M primers 85.8% of the animals proved to be freemartins. 40 blood samples were additionally analysed using PCR with zinc-finger-gene primers. 36 animals (90%) were identified as being freemartins by means of BOV97M and 34 animals (85%) by means of the zinc-finger-gene primer. The PCR method proved to be a rapid and very sensitive method for the diagnosis of freemartins and also suitable for routine testing. The BOV97M primer showed to have a higher Y chromosome specificity than the zinc-finger-gene primer.

Cochlear and retinal degeneration in the tubby mouse.

A number of autosomal recessive syndromes feature both sensorineural hearing loss and retinal degeneration. The mouse mutant tubby also combines hearing loss with progressive retinal degeneration, and thus may constitute a useful model of one form of human sensorineural deafness/retinal dystrophic syndrome. It has not been directly demonstrated that the hearing loss in this mouse involves the cochlea, however. We have examined the cochleas of adult tubby mice using light microscopy. The tubby cochlea shows pronounced degeneration of the organ of Corti and loss of afferent neurons in the base, with relative sparing of the apex. Our findings support the tubby mouse as a model of human sensorineural deafness/retinal dystrophic syndrome. Possible human counterparts include Usher's, Alstrom's, and Bardet-Biedl syndromes.

Binding of 9-cis-retinoic acid and all-trans-retinoic acid to retinoic acid receptors alpha, beta, and gamma. Retinoic acid receptor gamma binds all-trans-retinoic acid preferentially over 9-cis-retinoic acid.

Both 9-cis-retinoic acid (RA) and all-trans-RA (t-RA) compete for [3H]9-cis-RA binding to RA receptors (RAR alpha, beta, and gamma) in nucleosol fractions from transiently transfected COS-1 cells with IC50 values of approximately 12 and 5 nM, respectively. Curiously, 9-cis-RA competes for [3H]t-RA binding to mouse RAR alpha, beta, and gamma with IC50 values of 31, 8, and 60 nM, respectively, while t-RA itself does not exhibit such differential competition (IC50 values for RARs, 5 nM). A similar pattern is observed with human retinoic acid receptors (RARs). Differential binding of 9-cis-RA to the RAR beta and gamma receptors is also found following in vitro transcription and translation of these receptors. Displacement assays demonstrate that t-RA exhibits similar off-rates for RAR alpha, beta, and gamma. However, 9-cis-RA is 6-fold more rapidly displaced from RAR gamma than from RAR beta. When RAR-transfected COS-1 cells are incubated with [3H]t-RA, [3H]-9-cis-RA or various mixtures of these two radioligands, high performance liquid chromatography analysis demonstrates that the ligands bound in nucleosol fractions from RAR beta-transfected cells reflect the isomer content of the media. However, in identical whole cell assays, nucleosol fractions from RAR gamma-transfected cells preferentially bind t-RA over 9-cis-RA, consistent with the in vitro data. These binding kinetics in vitro and in whole cells suggest that there could be differences in the interactions of the receptor subtypes with the endogenous retinoic acids under physiologic conditions.