Coating of cochlear implant electrodes with bioactive DNA-loaded calcium phosphate nanoparticles for the local transfection of stimulatory proteins

Calcium phosphate nanoparticles were loaded with nucleic acids to enhance the on-growth of tissue to a cochlear implant electrode. The nanoparticle deposition on a metallic electrode surface is possible by electrophoretic deposition (EPD) or layer-by-layer deposition (LbL). Impedance spectroscopy showed that the coating layer did not interrupt the electrical conductance at physiological frequencies and beyond (1-40,000 Hz). The transfection was demonstrated with the model cell lines HeLa and 3T3 as well as with primary explanted spiral ganglion neurons (rat) with the model protein enhanced green fluorescent protein (EGFP). The expression of the functional protein brain-derived neurotrophic factor (BDNF) was also shown. Thus, a coating of inner-ear cochlear implant electrodes with nanoparticles that carry nucleic acids will enhance the ongrowth of spiral ganglion cell axons for an improved transmission of electrical pulses.

Local and Nonlocal Electron Dynamics of Au/Fe/MgO(001) Heterostructures Analyzed by Time-Resolved Two-Photon Photoemission Spectroscopy

Employing femtosecond laser pulses in front and back side pumping of Au/Fe/MgO(001) combined with detection in two-photon photoelectron emission spectroscopy, we analyze local relaxation dynamics of excited electrons in buried Fe, injection into Au across the Fe-Au interface, and electron transport across the Au layer at 0.6 to 2.0 eV above the Fermi energy. By analysis as a function of Au film thickness we obtain the electron lifetimes of bulk Au and Fe and distinguish the relaxation in the heterostructure's constituents. We also show that the excited electrons propagate through Au in a superdiffusive regime and conclude further that electron injection across the epitaxial interface proceeds ballistically by electron wave packet propagation.

Magneto-optical properties of Au upon the injection of hot spin-polarized electrons across Fe/Au(0 0 1) interfaces

We demonstrate a novel method for the excitation of sizable magneto-optical effects in Au by means of the laser-induced injection of hot spin-polarized electrons in Au/Fe/MgO(0 0 1) heterostructures. It is based on the energy- and spin-dependent electron transmittance of Fe/Au interface which acts as a spin filter for non-thermalized electrons optically excited in Fe. We show that after crossing the interface, majority electrons propagate through the Au layer with the velocity on the order of 1 nm fs^-1 (close to the Fermi velocity) and the decay length on the order of 100 nm. Featuring ultrafast functionality and requiring no strong external magnetic fields, spin injection results in a distinct magneto-optical response of Au. We develop a formalism based on the phase of the transient complex MOKE response and demonstrate its robustness in a plethora of experimental and theoretical MOKE studies on Au, including our ab initio calculations. Our work introduces a flexible tool to manipulate magneto-optical properties of metals on the femtosecond timescale that holds high potential for active magneto-photonics, plasmonics, and spintronics.

Fabrication of Robust Reference Tips and Reference Electrodes for Kelvin Probe Applications in Changing Atmospheres

The scanning Kelvin probe (SKP) is a versatile method for the measurement of the Volta potential difference between a sample and the SKP-tip (Δψ_sample^SKP-tip). Based on suitable calibration, this technique is highly suited for the application in corrosion science due to its ability to serve as a very sensitive noncontact and nondestructive method for determining the electrode potential, even at buried interfaces beneath coatings or on surfaces covered by ultrathin electrolyte layers, which are not accessible by standard reference electrodes. However, the potential of the reference (i.e., the SKP-tip) will be influenced by variations of the surrounding atmosphere, resulting in errors of the electrode potential referred to the sample. The objective of this work is to provide a stable SKP-tip which can be used in different or changing atmosphere, e.g., within a wide range of relative humidity (approximately 0-99%-rh) or varying O₂ partial pressure, without showing a change of its potential (note that the work functions measured in non-UHV atmospheres are electrochemical in nature [Hausbrand et al. J. Electrochem. Soc. 2008, 155 (7), C369-C379], and hence in the following we will refer to the potential of the SKP-tip instead of its work function). In that regard, the SKP-tip is in a first approach modified with self-assembled monolayers (SAMs) in order to create a hydrophobic barrier between the metallic surface and the surrounding atmosphere. The changes in potential upon varying relative humidity (ΔE_rh) of different bare metallic substrates are quantified, and it is shown that these potential differences cannot be minimized by SAMs. On the contrary, the ΔE_rh increases for every examined material system modified with SAMs. The major explanation for this observation is the dipole layer at the interface metal|SAM, causing an interfacial adsorption of water molecules even in a preferred orientation of their dipole moments, which leads to a changed work function and consequently to the correlated electrode potential. However, thin paraffin coatings were found to lead to a strongly reduced ΔE_rh, finally validated with novel robust Ag/Ag⁺ reference electrodes. It is also shown that nickel as SKP-tip material is seemingly more stable in varying atmospheric conditions compared to widely used Ni/Cr, stainless steel, or gold as SKP-tip material.

Femtosecond Spin Current Pulses Generated by the Nonthermal Spin-Dependent Seebeck Effect and Interacting with Ferromagnets in Spin Valves

Using the sensitivity of optical second harmonic generation to currents, we demonstrate the generation of 250-fs long spin current pulses in Fe/Au/Fe/MgO(001) spin valves. The temporal profile of these pulses indicates ballistic transport of hot electrons across a sub-100 nm Au layer. The pulse duration is primarily determined by the thermalization time of laser-excited hot carriers in Fe. Considering the calculated spin-dependent Fe/Au interface transmittance we conclude that a nonthermal spin-dependent Seebeck effect is responsible for the generation of ultrashort spin current pulses. The demonstrated rotation of spin polarization of hot electrons upon interaction with noncollinear magnetization at Au/Fe interfaces holds high potential for future spintronic devices.

Analysis of the time-resolved magneto-optical Kerr effect for ultrafast magnetization dynamics in ferromagnetic thin films

We discuss fundamental aspects of laser-induced ultrafast demagnetization probed by the time-resolved magneto-optical Kerr effect (MOKE). Studying thin Fe films on MgO substrate in the absence of electronic transport, we demonstrate how to disentangle pump-induced variations of magnetization and magneto-optical coefficients. We provide a mathematical formalism for retrieving genuine laser-induced magnetization dynamics and discuss its applicability in real experimental situations. We further stress the importance of temporal resolution achieved in the experiments and argue that measurements of both time-resolved MOKE rotation and ellipticity are needed for the correct assessment of magnetization dynamics on sub-picosecond timescales. The framework developed here sheds light onto the details of the time-resolved MOKE technique and contributes to the understanding of the interplay between ultrafast laser-induced optical and magnetic effects.

Nanoscale interface confinement of ultrafast spin transfer torque driving non-uniform spin dynamics

Spintronics had a widespread impact over the past decades due to transferring information by spin rather than electric currents. Its further development requires miniaturization and reduction of characteristic timescales of spin dynamics combining the sub-nanometre spatial and femtosecond temporal ranges. These demands shift the focus of interest towards the fundamental open question of the interaction of femtosecond spin current (SC) pulses with a ferromagnet (FM). The spatio-temporal properties of the impulsive spin transfer torque exerted by ultrashort SC pulses on the FM open the time domain for probing non-uniform magnetization dynamics. Here we employ laser-generated ultrashort SC pulses for driving ultrafast spin dynamics in FM and analysing its transient local source. Transverse spins injected into FM excite inhomogeneous high-frequency spin dynamics up to 0.6 THz, indicating that the perturbation of the FM magnetization is confined to 2 nm.

Chemical energy dissipation at surfaces under UHV and high pressure conditions studied using metal–insulator–metal and similar devices

Thin film metal heterostructures have allowed new light to be shed on the dissipation of chemical energy into electric excitations on metal surfaces.

Thermal desorption spectroscopy from the surfaces of metal-oxide-semiconductor nanostructures

An experimental setup, which combines direct heating and temperature measurement of metal nanofilms allowing temperature programmed desorption experiments is described. This setup enables the simultaneous monitoring of the thermal desorption flux from the surface of chemi-electric devices and detection of chemically induced hot charge carriers under UHV conditions. This method is demonstrated for the case of water desorption from a Pt/SiO2-n-Si metal-oxide-semiconductor nanostructure.

Thermal properties of the stationary current in mesoporous Pt/TiO2 structures in an oxyhydrogen atmosphere

We report on the effect of temperature on the electric current induced in the mesoporous Pt/TiO2 structure by the room temperature surface chemical reaction of hydrogen and oxygen,13,14 which helps to unveil the physical origin of this current and the related electromotive force (chemi-EMF). We found that the temperature dependence of this reaction current has a clear multipeak structure, suggesting that at least two distinct processes contribute to the current generation. We suggest that the output current represents the interplay of both chemical and electrical processes, evidenced by the metastability of the room temperature reaction and by matching one of the current peaks with a water desorption peak for TiO2.

Combining scanning tunneling microscopy and synchrotron radiation for high-resolution imaging and spectroscopy with chemical, electronic, and magnetic contrast

The combination of high-brilliance synchrotron radiation with scanning tunneling microscopy opens the path to high-resolution imaging with chemical, electronic, and magnetic contrast. Here, the design and experimental results of an in-situ synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system are presented. The system is designed to allow monochromatic synchrotron radiation to enter the chamber, illuminating the sample with x-ray radiation, while an insulator-coated tip (metallic tip apex open for tunneling, electron collection) is scanned over the surface. A unique feature of the SXSTM is the STM mount assembly, designed with a two free-flex pivot, providing an angular degree of freedom for the alignment of the tip and sample with respect to the incoming x-ray beam. The system designed successfully demonstrates the ability to resolve atomic-scale corrugations. In addition, experiments with synchrotron x-ray radiation validate the SXSTM system as an accurate analysis technique for the study of local magnetic and chemical properties on sample surfaces. The SXSTM system's capabilities have the potential to broaden and deepen the general understanding of surface phenomena by adding elemental contrast to the high-resolution of STM.

Electronic excitations induced by hydrogen surface chemical reactions on gold

Associated with chemical reactions at surfaces energy may be dissipated exciting surface electronic degrees of freedom. These excitations are detected using metal-insulator-metal (MIM) heterostructures (Ta-TaOx-Au) and the reactions of H with and on a Au surface are probed. A current corresponding to 5×10(-5) electrons per adsorbing H atom and a marked isotope effect are observed under steady-state conditions. Analysis of the current trace when the H atom flux is intermitted suggests that predominantly the recombination reaction creates electronic excitations. Biasing the front versus the back electrode of the MIM structure provides insights into the spectrum of electronic excitations. The observed spectra differ for the two isotopes H and D and are asymmetric when comparing negative and positive bias voltages. Modeling indicates that the excited electrons and the concurrently created holes differ in their energy distributions.

Expression of splice variants of 1alpha-hydroxylase in mcf-7 breast cancer cells

1,25-Dihydroxyvitamin D(3) (calcitriol) is the most active natural metabolite of Vitamin D(3). It has strong antiproliferative and differentiating effects on various cell types including breast cancer cells. 25-Hydroxyvitamin D(3)-1alpha-hydroxylase (1alpha-hydroxylase, CYP27B1) is one of the key enzymes in the formation of calcitriol. It has been found in breast cancer cells suggesting an autocrine regulation of formation of calcitriol in these cells. Alternative splicing of the encoding genes for this enzyme can possibly play a role in regulating the enzyme level and can explain tissue specific variations of 1alpha-hydroxylase activity. Splice variants containing intron 1 may encode for truncated proteins with deletion of protein domains which are essential for its enzymatic activity. In order to obtain more information on the abundance of 1alpha-hydroxylase splice variants, we performed a highly specific nested touchdown PCR in MCF-7 cells. The full-length sequence of 1alpha-hydroxylase and two different splice variants of this enzyme containing intron 1 were isolated. By Western blot technique we then confirmed the protein products of the full-length enzyme and its splice variants. We hypothesize that that the expression of splice variants can lead to a quantitatively lower expression of the mRNA of the full-length enzyme. The abundance of less active 1alpha-hydroxylase protein variants can alter the local synthesis of calcitriol in the cells and may explain variations of enzymatic activity in different cells and tissues.

Carcinosarcomas--a retrospective analysis of 21 patients

BACKGROUND

Carcinosarcomas (CS) are mixed epithelial and stromal tumours with both components being malignant. Twenty-one patients with carcinosarcomas who were treated at the University of Saarland, Germany, are presented.

PATIENTS AND METHODS

The hospital records of all patients were reviewed.

RESULTS

The mean age range for homologue CS (homCS) was 60.7 years and for heterologue CS (hetCS) 68.4 years. Post-menopausal bleeding and abdominal pain were the main symptoms. Treatment modalities included surgery, adjuvant radiation therapy and various chemotherapy regimens. The median follow-up time was 17.6 months (homCS) and 31.1 months (hetCS). The 1-year survival rate was 55.6% (hetCS 58.3%) and the 5-year survival rate was 11.1% (hetCS 8.3%).

CONCLUSION

Carcinosarcoma is a uterine sarcoma with a poor prognosis. Treatment includes surgery and adjuvant chemotherapy, whereas radiotherapy does not necessarily lead to a benefit. Treatment with trastuzumab might be a new approach in the therapy of HER-2/neu-positive CS.

Modulation of MAPK ERK1 and ERK2 in VDR-positive and -negative breast cancer cell lines

1alpha-25-Dihydroxyvitamin D3 (calcitriol), the biologically active metabolite of vitamin D, is known to regulate calcium and phosphate levels in bone metabolism. It is also known to influence proliferation and differentiation in carcinoma cells mediated by the vitamin D receptor (VDR). The antiproliferative effects of calcitriol are believed to be mediated by the nuclear pathway via binding the activated receptor to vitamin D-responsive elements. This induces the vitamin D-responsive genes. Another possible pathway might be the MAPK-cascade or rapid response pathway. The interaction of calcitriol and the MAP-kinase-cascade was evaluated on VDR-positive MCF-7 cells and VDR-negative MDA-MB-231 breast cancer cells. The cells were incubated with calcitriol solution at 10(-7) M and 10(-9) M, or ethanol as controls, for up to 48 h. The effects of calcitriol were measured by semi-quantitative Western blotting. Calcitriol stimulated the MAP-kinases ERK1 and ERK2. A biphasic activation was found for calcitriol in VDR-positive cells after incubation for 5 to 20 min and from 2 to 24 h. However, early activation of ERK1 and ERK2 was also demonstrated in VDR-negative cells. In the controls, ethanol also induced the MAPK-cascade at 5 to 10 min. Calcitriol induction was demonstrated after incubation from 2 to 24 h. In conclusion, it seems that the early induction of the MAPK-cascade was independent of the VDR. A calcitriol-induced MAPK activation was shown after 4 h, which may have been caused by activation of the nuclear receptor pathway.

Presentation of splice variants of 1-alpha-hydroxylase in MCF-7 breast cancer cells

20097

Background: Calcitriol (1,25-dihydroxyvitamin D3) is the most active metabolite of vitamin D. It is known for its antiproliferative and differentiating effects on many cell populations including MCF-7 and other breast cancer cells. 1α-hydroxylase (CYP27B1) one of the key enzymes has been found in breast cancer cells suggesting an autocrine regulation of producing calcitriol. An alternative splicing of the encoding genes for the1α-hydroxylase might play a role in regulating enzyme levels and can explain tissue specific variations of the enzyme activity. Splice variants containing intron 1 may encode for truncated proteins with deletion of protein domains which are essential for its enzymatic activity. Methods: In order to obtain more information on the abundance of 1α-hydroxylase splice variants, we performed a highly specific nested touchdown PCR in MCF-7 cells. The protein products of the full length enzyme and its slice variants were confirmed by Western Blot. Results: The full length sequence of 1α-hydroxylase and two different splice variants including intron 1 were isolated. Conclusion: We hypothesize that the expression of the splice variants can lead to a quantitatively lower expression the mRNA of the full length enzyme. The abundance of less active 1α-hydroxylase protein products can alter the local synthesis of calcitriol in the cells and may explain variations of enzymatic activity in different cells and tissues.

No significant financial relationships to disclose.

Endometrial stromal sarcomas--a retrospective analysis of 11 patients

BACKGROUND

Endometrial stromal sarcoma (ESS) is a malignant tumour with its origin in the endometrial stroma. Little is known about the pathogenesis, risk factors, optimal therapy or outcome of this disease.

PATIENTS AND METHODS

Eleven patients with ESS, treated between 1972 and 1996, are reported on. The hospital records of all the patients, including pathology and operative reports, were reviewed and information on treatment, recurrence and survival was obtained.

RESULTS

The mean age of our patients was 56.6 years. The main symptom was abnormal vaginal bleeding. Most patients were diagnosed at FIGO stage I. Treatment modalities were surgery, radiation and, in one patient, chemotherapy. The median follow-up time was 42.1 months; 27.3% of the patients had local recurrence. The 1-year, 2-year and 5-year survival rates were 36.3%, 18.1% and 9.1%, respectively.

CONCLUSION

ESS is a uterine sarcoma with a difficult differential diagnosis. Patients are frequently diagnosed in an early tumour stage but still experience local or distant recurrence. The prognosis is poor, with early recurrence and low long-time survival rates. The treatment includes surgery and adjuvant radiation, with endocrine therapy being a promising new approach. In order to obtain more information about the pathogenesis of the tumour and to find the optimal therapy, it is necessary that studies, even with small numbers of patients, are undertaken.

[Metastatic breast cancer: options for metastasectomy]

Usually, the therapy of metastatic breast cancer consists of chemotherapy or endocrine therapy, because even in the case of isolated metastases in one organ, diffuse tumor cell dissemination exists, so that local surgical treatment does not seem sensible. Particurlarly in patients with hepatic or pulmonary metastases the indication for hepatic or pulmonary metastasectomy should be individualized, as hepatic or pulmonary metastases usually develop during a phase of disease, when extrahepatic or -pulmonary metastases also can be detected. Only in patients with long disease-free interval, with isolated hepatic or pulmonary metastases, and the possibility of R0-resection is hepatic or pulmonary metastasectomy a therapeutic option in selected cases.

[Treatment of breast cancer patients with brain metastases]

Treatment of patients with brain metastases is based on an interdisciplinary approach. It is essential to perform a differenciated indication for procedures with consideration of all therapeutical options like modalities of radiotherapy, surgery and oncology. In the case of multiple brain metastases the whole brain radiotherapy is the standard of treatment, while in case of a single or solitary brain metastasis surgical procedures followed by radiotherapy should be preferred.

Kinetic electron excitation in atomic collision cascades

The kinetic excitation of electrons upon bombardment of a solid surface with energetic ions is investigated. Using a metal-insulator-metal junction, hot electrons produced by the projectile impact are detected with excitation energies well below the vacuum level. The results provide information that cannot be accessed by electron emission experiments. The observed tunneling current depends on the projectile energy and the bias voltage across the junction, opening the possibility of internal excitation spectroscopy.

Genital skin fibroblasts (GF) of patients with androgen insensitivity syndrome express higher insulin-like growth factor binding protein (IGFBP)-2, -3 and -5 than GF of normally virilized males

BACKGROUND

We investigated the effects of androgens, estradiol (E2) and insulin-like growth factor (IGF)-I on IGF-II, insulin-like growth factor binding protein (IGFBP)-2, -3 and -5 and mRNA in genital fibroblasts (GF) from patients with complete androgen insensitivity (CAIS) and normally virilized males (C).

METHODS

Proteins were measured by specific RIA and Western ligand blot, and specific mRNA levels by RT-PCR normalized by GAPDH levels.

RESULTS

Secretion of IGF-II was lowered in CAIS (p<0.001) GF and by testosterone + IGF-I in C GF. Secretion of IGFBP-2 was higher (p<0.001) in CAIS GF and IGFBP-2 mRNA levels were increased by E2 in C GF (p<0.05). E2 stimulated IGFBP-2, -3 and -5 expression in CAIS GF. CAIS GF also secreted more IGFBP-3 (p<0.001) and accumulated 3-5 times more IGFBP-5 mRNA than C GF (p<0.001).

CONCLUSION

In contrast to C GF, the availability of IGF-II in CAIS GF is apparently decreased by two facts: by the decreased expression and by increased expression of IGFBP-2, -3 and -5. Furthermore, E2 and IGF-I modulate the expression of IGF-II and IGFBP in GF. This may play a role in the failure to develop male external genitals in CAIS patients.

Taxanes in the first-line chemotherapy of metastatic breast cancer: review

Taxanes belong to the most effective agents in the treatment of advanced and non-hormone responsive breast cancer. Several recently published phase III studies have examined the role of taxane-anthracycline combinations in the first line treatment of metastatic breast cancer. Especially, patients with symptomatic visceral spread seem to benefit from taxanes containing polychemotherapy that is adequately dosed. Polychemotherapy with taxanes appears to be more effective than monotherapy. But at present, there are no adequate data concerning the comparison of taxane-monotherapy and anthracycline-containing polychemotherapy. New hopeful results with respect to efficacy and toxicity are reported from the docetaxel-capecitabine polychemotherapy. Thus, the combination of anthracyclines (adriamycin, doxorubicin) and taxanes (docetaxel, paclitaxel) is a promising tool in the treatment of metastatic breast cancer. New interesting combinations are under investigation.

Hepatic metastasectomy as a cytoreductive strategy for the treatment of liver metastases in breast cancer: review of literature

The resection of liver metastases in breast cancer patients is a controversial therapeutical approach. No data of prospective randomized trials are available, thus evidence for the potential role of hepatic metastasectomy rests on retrospective studies with a small number of patients. Techniqual advances however have rendered hepatic metastasectomy safe and the long-term results of some studies possibly support the role of a surgical approach in selected patients.

Effect of tamoxifen and 2-methoxyestradiol alone and in combination on human breast cancer cell proliferation

Endocrine therapy is widely accepted for the treatment of hormone receptor-positive breast cancer. However, in many cases eventually resistance will develop and tumor regrows. Combination therapy may be one way to resolve this problem. In the present study we investigated the effect of a combination of the widely used antiestrogen tamoxifen with the endogenous estradiol metabolite 2-methoxyestradiol (2-ME) on the proliferation of human estrogen receptor-positive and receptor-negative breast cancer cells. The receptor-positive cell line MCF-7 and the receptor-negative cell line BM were treated with 4-hydroxytamoxifen (4-OHTam) and 2-methoxyestradiol in the concentration range of 0.8-25 microM alone and equimolar combinations for 4 days. The proliferation of the cells was determined using the ATP-chemosensitivity test.4-Hydroxytamoxifen inhibited proliferation of MCF-7 and BM cells with IC(50) values of 31 and 10 microM, the corresponding figures for 2-methoxyestradiol were 52 and 8 microM. The combination showed IC(50) values of 6 microM and 4 microM. These results indicate that a combination of tamoxifen with 2-methoxyestradiol showed an additive inhibitory effect concerning the proliferation of estrogen receptor-positive and receptor-negative breast cancer cell lines. Thus a combination of these substances may allow ameliorating of adverse events of tamoxifen by reducing its concentrations and probably also drug resistance and should be tested in clinical trials.

Decreased expression of IGF-II and its binding protein, IGF-binding protein-2, in genital skin fibroblasts of patients with complete androgen insensitivity syndrome compared with normally virilized males

The action of androgen by way of the AR is required for the development of male gonads and external genitalia. The interplay between androgens and the somatotropic axis, in particular the IGFs in sexual development, is currently under thorough investigation. The IGF system is thought to mediate the androgen action in androgen-responsive cells. To investigate the interaction of androgens with the IGF system, we compared the expression of IGFs and IGF-binding proteins in cultured genital skin fibroblasts from nine patients with the syndrome of complete androgen insensitivity with that in genital skin fibroblasts from 10 normally virilized males. Mutations in the AR gene and/or abnormalities of the AR protein in the immunoblot were detected in all complete androgen insensitivity genital skin fibroblast strains. They caused a complete failure of DHT binding. RIA and RT-PCR demonstrated that the genital skin fibroblast strains expressed IGF-II, IGF-binding protein-2, and IGF-binding protein-3, but no IGF-I. Most strikingly, complete androgen insensitivity genital skin fibroblast strains produced significantly lower IGF-II (P < 0.001; 42.2 +/- 9.7 vs. 106.9 +/- 11.8 ng/mg protein) and IGF-II mRNA (P < 0.01, by RT-PCR) than control genital skin fibroblast strains. The production of IGF-binding protein-2 was also decreased (P < 0.03) in complete androgen insensitivity genital skin fibroblasts, whereas that of IGF-binding protein-3 did not differ. Furthermore, high levels of IGF-binding protein-5 mRNA were detected in all genital skin fibroblast strains, whereby the 28-kDa band in the ligand blot, probably representing IGF-binding protein-5, was more abundant in complete androgen insensitivity genital skin fibroblasts. Exposure of the genital skin fibroblasts to T (5 x 10(-8) M) had only weak effects on the expression of IGFs and IGF-binding proteins. In conclusion, although the mechanism underlying these differences requires further study, it is conceivable that in addition to the endocrine actions of IGF-I, IGF-II and IGF-binding protein-2, as local growth factors, are involved in the mediation of androgen action and growth of genital tissues.