The impact of GSTM1/GSTT1 polymorphism for the risk of oral cancer.

OBJECTIVES: Since development of oral squamous cell cancer (OSCC) is triggered by various noxa, different variants of the antioxidant glutathione S-transferases (GSTs) can counteract toxic compounds (e.g., tobacco smoke). Because different polymorphisms of GST are known to have an increased sensitivity to carcinogenic agents, the aim of this study was to analyze whether GSTM1 or GSTT1 polymorphisms increase the risk for the development of OSCC. MATERIALS AND METHODS: GSTM1 and GSTT1 polymorphism was examined in healthy volunteers (n = 93) and in patients with OSCC (n = 100) by PCR after brush biopsy of oral mucosa. Odds ratio (OR) was calculated to evaluate the risk of oral cancer development. RESULTS: GSTM1 and GSTT1 deletion was found in 57% (53/93) and 18% (17/93), respectively, in healthy patients, while the OSCC group showed 57% (57/100) for GSTM1 deletion and 22% (22/100) with a deletion of GSTT1. Odds ratio for GSTM1 polymorphism was 1.00 and for GSTT1 1.26. Comparing smokers and nonsmokers with GSTM1 deletion polymorphism, OR was 4.35, while smokers without GSTM1 deletion showed an OR of 1.45. Adapting these data to the smoking habits of the general population in Germany, the OR was 9.25 for smokers with a GSTM1 deletion and OR 6.68 for smokers without a GSTM1 deletion. In smokers with GSTT1 deletion polymorphism, OR was 1.6 (adapted to the smoking habits of the general population: OR 6.16) and 3.16 (OR 8.56) in smokers without deletion in GSTT1 gene. CONCLUSIONS: Analysis of GST-M1 polymorphism in smokers could help to identify patients with a higher risk for the development of oral cancer. CLINICAL RELEVANCE: Early detection of OSCC due to a close meshed monitoring program for patients with GST-M1 polymorphism could help to improve the patient outcome. For polymorphism investigations, the oral brush biopsy is a sufficient method to gain DNA material.

Thermal and structural characteristics of oligo(3-hexylthiophene)s (3HT)n, n = 4-36.

This study is concerned with the thermal and structural characteristics of a series of precisely defined, monodisperse, regioregular oligo(3-hexylthiophene)s (3HT)n of n = 4-36. We find that these model compounds can feature two distinctly different solid-state structures, i.e., the more classical polymorph Form I in which the hexyl side-chains are not interdigitated and Form II in which they are. The thermodynamic equilibrium melting temperatures of these phases differ as much as ~180 °C, with 116 °C for Form II and 298 °C for Form I. Furthermore, polymorph II featured an enthalpy of melting of ~3 times that of Form I and a rate of crystallization that is ~1 order of magnitude lower than that of Form I. A crossover of the thermodynamically preferred Form II into the kinetically favored Form I is observed at a number of repeat units of 12. In the regime 10 ≤ n ≤ 21 the oligo(3-hexylthiophene)s could readily be reversibly converted from one polymorph to another by appropriate processing treatments. The relevance of these findings for the polymeric form (P3HT) is discussed.

Influence of bisphosphonates on the osteoblast RANKL and OPG gene expression in vitro.

Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are widely known to be associated with osteonecrosis of the jaw (BONJ). The objective of this study was to evaluate the effect of bisphosphonates on the gene expression of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) in vitro. Nitrogen-containing and non-nitrogen containing bisphosphonates have been compared. Human osteoblasts were stimulated with zoledronate and ibandronate at concentrations of 5 × 10(-5) M, 5 × 10(-6) M, and 5 × 10(-7) M over the experimental period of 14 days. Furthermore, the hOB cell lines were stimulated by clodronate at concentrations of 5 × 10(-3) M, 5 × 10(-5) M, and 5 × 10(-6) M. At each point in time, the gene expression levels of RANKL and OPG were quantified by real-time RT-PCR. The results showed a moderate enhancement of OPG gene expression whereas RANKL gene expression was strongly increased by nitrogen-containing bisphosphonates reaching a maximum after 14 days at high concentrations of 5 × 10(-5) M. Lower concentrations did not enhance the RANKL and OPG expression considerably. The non-nitrogen-containing bisphosphonate clodronate, however, effected OPG and RANKL gene expression much less, even at higher concentrations of 5 × 10(-3) M. The above-mentioned data suggest an enhanced RANKL/OPG gene expression after stimulation by bisphosphonates. Interestingly, clodronate might have little influence on osteoblast/osteoclast interaction with respect to OPG and RANKL gene expression.

Controllable processes for generating large single crystals of poly(3-hexylthiophene).

Sowing the seeds: A simple strategy based on self-seeding allows large single crystals of long regioregular poly(3-hexylthiophene) chains to be grown from solution. When appropriately crystallized, materials differing in their degrees of regioregularity and molecular weights formed monoclinic form II crystals with interdigitated hexyl side groups (see picture).

Diagnostic efficiency of differentiating small cancerous and precancerous lesions using mucosal brush smears of the oral cavity--a prospective and blinded study.

The aim of this study was to evaluate the diagnostic accuracy of oral brush biopsy to identify early malignancy. One hundred and eighty-six brush biopsies of suspicious mucosal lesions were obtained, haematoxilin and eosin (H&E)-stained and compared with the histology of conventional excision biopsies of the same site performed concomitantly. The sensitivity for identifying squamous cell carcinoma (SCC) was 88.5%. High-risk lesions including squamous intraepithelial neoplasia (SIN II, SIN III) and SCC were identified with a sensitivity of 86.4%, using a pap-analogous classification, which is considered to be carcinomatous, as well as moderate and severe dysplastic cells positive. Depending on the cytopathologic definition for malignancy and the tumour size, the test accuracy varied: Extending the cytopathologic criteria for malignancy by defining all dysplastic or malignant cytopathologic findings as positive, the sensitivity was increased to 95.2% at the expense of the specificity, which was reduced from 94.9% to 82.3%. Separately analysing SCCs of less than 20 mm, the sensitivity was reduced by 9.5% to 78%. Although small malignant lesions seem to be less reliable by the conventional oral brush biopsy, it is a useful screening instrument for early diagnosis of suspicious, epithelial lesions and could therefore contribute to improved cancer prognosis.

Effectiveness of autofluorescence to identify suspicious oral lesions--a prospective, blinded clinical trial.

Regular screening through white light inspection of the entire oral mucosa is the most important examination method to identify precancerous lesions and early oral carcinoma. Additionally, the physiologic autofluorescence of the oral mucosa has been described as a novel screening method for the detection of mucosal lesions that are not visible by white light. This study aimed to evaluate the sensitivity and specificity of the autofluorescence examination. Seventy-eight patients were examined in this study. All of them suffered from suspicious oral mucosal lesions. Two different investigation methods were applied: the standard examination by white light and an examination by a novel light source of 400 nm that evoked a green light emission (>500 nm) in normal mucosa. It was proposed that malignant oral mucosal lesions show different autofluorescence characteristics than the green autofluorescence of healthy mucosa. Red autofluorescence indicated SCC with a sensitivity of 20% and a specificity of 98%. The results showed that dysplasia and carcinoma could be identified with a sensitivity of 96% and a specificity of 18% by using the autofluorescence method. The sensitivity decreased according to the grade of mucosal keratosis and was influenced by the localisation of the lesion. In conclusion, benign as well as malignant oral lesions could not be distinguished by a diminished autofluorescence signal. A red autofluorescence signal, however, could indicate cancerous processes of the oral mucosa.

Anisotropic charge transport in large single crystals of π-conjugated organic molecules.

The electronic properties of organic semiconductors depend strongly on the nature of the molecules, their conjugation and conformation, their mutual distance and the orientation between adjacent molecules. Variations of intramolecular distances and conformation disturb the conjugation and perturb the delocalization of charges. As a result, the mobility considerably decreases compared to that of a covalently well-organized crystal. Here, we present electrical characterization of large single crystals made of the regioregular octamer of 3-hexyl-thiophene (3HT)8 using a conductive-atomic force microscope (C-AFM) in air. We find a large anisotropy in the conduction with charge mobility values depending on the crystallographic orientation of the single crystal. The smaller conduction is in the direction of π-π stacking (along the long axis of the single crystal) with a mobility value in the order of 10(-3) cm(2) V(-1) s(-1), and the larger one is along the molecular axis (in the direction normal to the single crystal surface) with a mobility value in the order of 0.5 cm(2) V(-1) s(-1). The measured current-voltage (I-V) curves showed that along the molecular axis, the current followed an exponential dependence corresponding to an injection mode. In the π-π stacking direction, the current exhibits a space charge limited current (SCLC) behavior, which allows us to estimate the charge carrier mobility.

Soft tissue healing at one-piece zirconia implants compared to titanium and PEEK implants of identical design: a histomorphometric study in the dog.

This study aimed to histomorphometrically evaluate the soft tissue reactions of one-piece zirconia implants versus titanium implants in regard to their insertion depth. Four one-piece implants of identical geometry were inserted on each side of six mongrel dogs: an uncoated zirconia implant, a zirconia implant coated with a calcium liberating titanium oxide, a titanium implant, and an experimental implant made of a synthetic material. Using a split-mouth design, they were inserted in both submerged and nonsubmerged healing modes. After 4 months, dissected blocks were stained with toluidine blue to histologically assess the marginal portion of the implant mucosa, apical extension of the barrier epithelium, and margin level of bone-to-implant contact. The inflammation status at the crestal part of the implant was assessed as well. The histomorphology presented the typical soft tissue configuration of barrier epithelium and connective tissue near the bone-to-implant contact. Histomorphometrically, the length of the barrier epithelium did not differ significantly concerning material type or healing modality. Furthermore, the inflammation signs were higher with nonsubmerged implants. The submerged uncoated zirconia implants, however, showed few signs of inflammation. Within the limits of this study, it is concluded that uncoated and coated zirconia implants are capable of establishing sufficient soft tissue configurations that are comparable to those of titanium implants.

GDF-5 and BMP-2 regulate bone cell differentiation by gene expression of MSX1, MSX2, Dlx5, and Runx2 and influence OCN gene expression in vitro.

Recombinant human growth/differentiation factor 5 (rhGDF-5) and recombinant human bone morphogenetic protein 2 (rhBMP-2), as members of the transforming growth factor Β family, influence bone formation and differentiation. This in vitro osteoblast cell culture study investigated the molecular biologic effect of these growth factors on regulator gene expression of the homebox proteins MSX1 and MSX2 as well as distal-less homebox 5 (Dlx5) and runt-related transcription factor 2 (Runx2/Cbfa1). Concerning effector genes, the messenger ribonucleic acids of osteocalcin (OCN) were quantified using a reverse transcriptase real-time polymerase chain reaction. Over a period of 15 days, osteoblasts were stimulated and analyzed at days 1, 2, 5, 10, and 15. rhGDF-5 and rhBMP-2 were applied in concentrations of 100, 500, and 1,000 ng/mL. The results showed enhanced gene expression of MSX1 and MSX2 by the lower rhGDF-5 concentration (100 ng/mL) during the first 48 hours and a marginally enhanced gene expression of Runx2 and OCN in a dose-dependent manner. The rhBMP-2 stimulation showed enhanced MSX1 and MSX2 gene expression with peaks at 24 and 240 hours; Runx2 and OCN were more highly expressed than the unstimulated control with the 100-ng/mL concentration. rhGDF-5 seems to stimulate early osteoblast differentiation and extracellular matrix production, while rhBMP-2 seems to boost early and late osteoblast differentiation. Low growth factor concentrations appeared to be more effective in terms of gene expression.

Zoledronate, ibandronate and clodronate enhance osteoblast differentiation in a dose dependent manner--a quantitative in vitro gene expression analysis of Dlx5, Runx2, OCN, MSX1 and MSX2.

Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are known to be associated with osteonecrosis of the jaw (BONJ). There are two groups of bisphosphonates: the nitrogen-containing bisphosphonates, e.g. zoledronate and ibandronate, and the non-nitrogen-containing bisphosphonates, e.g. clodronate. Their impact on bone metabolism seems to differ. The objective of this study was to compare the osteogenic differentiation potency of these two pharmacologic groups. Human osteoblasts were stimulated with zoledronate and ibandronate at concentrations of 5×10(-5) M, 5×10(-6) M and 5×10(-7) M over the experimental periods of 1, 2, 5, 10 and 14 days. Clodronate was applied with concentrations of 5×10(-3), 5×10(-5) M and 5×10(-6) M. At each time point, the cells were dissolved, the mRNA extracted, and the gene expression level of the osteoblast specific differentiation markers of the homeobox transcription factors MSX1 and MSX2, the distal-less homeobox 5 (Dlx5), the Runt-related transcription factor 2 (Runx2/CBF1a) and osteocalcin (OCN) were quantified by Real-Time PCR. The gene expression was compared to an unstimulated osteoblast cell culture as control. The results showed a significant difference between the nitrogen-containing and the non-nitrogen-containing bisphosphonates. Zoledronate and ibandronate at concentrations of 5×10(-5) M enhanced the gene expression of all differentiation markers by several hundred folds compared to unstimulated control after 10 days, whereas clodronate had less influence on gene expression, even at higher concentrations of 5×10(-3) M. Lower concentrations of zoledronate and ibandronate, however, led to a decreased gene expression. These data confirm the results of other studies which have shown the osteogenic stimulus on osteoblasts in a dose dependent manner. The nitrogen-containing bisphosphonates appear to enhance bone density by stimulation of osteoblast differentiation. Non-nitrogen-containing bisphosphonates seem to have less influence on osteoblast differentiation.

The impact of bisphosphonates on the osteoblast proliferation and Collagen gene expression in vitro.

BACKGROUND: Bisphosphonates are widely used in the clinical treatment of bone diseases with increased bone resorption. In terms of side effects, they are known to be associated with osteonecrosis of the jaw (BONJ).The objective of this study was to evaluate the effect of bisphosphonates on osteoblast proliferation by cell count and gene expression analysis of cyclin D1 in vitro. Furthermore, the gene expression of the extracellular matrix protein collagen type I was evaluated. Nitrogen-containing and non-nitrogen-containing bisphosphonates have been compared on gene expression levels. METHODS: Human osteoblast obtained from hip bone were stimulated with zoledronate, ibandronate and clodronate at concentrations of 5 x 10-5M over the experimental periods of 1, 2, 5, 10 and 14 days. At each point in time, the cells were dissolved, the mRNA extracted, and the gene expression level of cyclin D1 and collagen type I were quantified by Real-Time RT-PCR. The gene expression was compared to an unstimulated osteoblast cell culture for control. RESULTS: The proliferation appeared to have been influenced only to a small degree by bisphosphonates. Zolendronate led to a lower cyclin D1 gene expression after 10 days. The collagen gene expression was enhanced by nitrogen containing bisphosphonates, decreased however after day 10. The non-nitrogen-containing bisphosphonate clodronate, however, did not significantly influence cyclin D1 and collagen gene expression. CONCLUSIONS: The above data suggest a limited influence of bisphosphonates on osteoblast proliferation, except for zoledronate. The extracellular matrix production seems to be initially advanced and inhibited after 10 days. Interestingly, clodronate has little influence on osteoblast proliferation and extracellular matrix production in terms of cyclin D1 and collagen gene expression.