Dual role of SIRT1 in UVB-induced skin tumorigenesis.

The protein deacetylase SIRT1 regulates various pathways in metabolism, aging and cancer. However, the role of SIRT1 in skin cancer remains unclear. Here, using mice with targeted deletions of SIRT1 in their epidermis in both resistant B6 and sensitive SKH1 hairless backgrounds, we show that the role of SIRT1 in skin cancer development induced by ultraviolet B (UVB) radiation is dependent on its gene dose. Keratinocyte-specific heterozygous deletion of SIRT1 promotes UVB-induced skin tumorigenesis, whereas homozygous deletion of SIRT1 suppresses skin tumor development but sensitizes the B6 mice to chronic solar injury. In mouse skin, SIRT1 is haploinsufficient for UVB-induced DNA damage repair and expression of xeroderma pigmentosum C (XPC), a protein critical for repairing UVB-induced DNA damage. As compared with normal human skin, downregulation of SIRT1 is in parallel with downregulation of XPC in human cutaneous squamous cell carcinoma at both the protein and mRNA levels. In contrast, homozygous SIRT1 deletion in mouse skin augments p53 acetylation and expression of its transcriptional target Noxa, and sensitizes the epidermis to UVB-induced apoptosis in vivo, while heterozygous SIRT1 deletion has no such effect. The gene dosage-dependent function of SIRT1 in DNA repair and cell survival is consistent with the dual roles of SIRT1 in UVB-induced skin tumorigenesis. Our results reveal the gene dosage-dependent in vivo functions of SIRT1 in skin tumorigenesis and may shed light on the role of SIRT1 in epithelial cancer induced by DNA damage.

UVB-induced ERK/AKT-dependent PTEN suppression promotes survival of epidermal keratinocytes.

Ultraviolet (UV) radiation in sunlight is the major environmental cause of skin cancer. PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a proven critical tumor suppressor. We report here that UVB downregulates PTEN in primary human keratinocytes, human HaCaT keratinocytes and mouse skin. As compared with normal skin, PTEN levels are reduced in human actinic keratosis, a precancerous skin lesion caused by solar UV. PTEN downregulation is mediated by two mechanisms: (1) PTEN is cleaved by active caspase in apoptotic cells in which AKT activation is reduced; and (2) PTEN transcription is suppressed in surviving cells, and this suppression is independent of caspase activation and occurs in parallel with increased ERK and AKT activation. We report here that the combination of ERK and AKT activation is crucial for PTEN suppression in surviving cells following UVB irradiation. AKT activation is higher in UVB-irradiated surviving cells as compared with unirradiated cells. The ERK and AKT pathways are involved in sustaining PTEN suppression in UVB-exposed cells. Increasing PTEN expression enhances apoptosis of keratinocytes in response to UVB irradiation. Our findings indicate that (1) UVB radiation suppresses PTEN expression in keratinocytes; and (2) the ERK/AKT/PTEN axis may form a positive feedback loop following UVB irradiation. Our identification of PTEN as a critical molecular target of UVB provides new insights into the pathogenesis of skin cancer.

Inflammation of actinic keratoses subsequent to therapy with sorafenib, a multitargeted tyrosine-kinase inhibitor.

The Ras-Raf-MEK-ERK signalling pathway is frequently dysregulated in human malignancies, as is angiogenesis and the vascular endothelial growth factor receptor (VEGF/VEGFR) pathway. These kinases are therefore important anticancer targets. The novel, oral treatment sorafenib (BAY 43-9006), has been shown to be an inhibitor of VEGFR, Raf and platelet-derived growth factor in clinical trials against a variety of cancers, with the greatest activity to date observed in metastatic renal cancer. Although side-effects with this targeted therapy are usually not dose-limiting, they frequently involve the skin, and consist of a maculopapular rash, palmar-plantar dysaesthesia, alopecia and xerosis. In this report, we present two patients in whom treatment with sorafenib resulted in inflammation of actinic keratosis, which in some cases progressed to invasive squamous cell carcinoma. This side-effect is of clinical importance, as early recognition is critical for early treatment and may represent a source of additional morbidity to these patients.

Treatment of radiation-relapsing primary cutaneous B-cell lymphoma with an anti-CD20 monoclonal antibody.

Primary cutaneous B cell lymphomas have a high recurrence rate after treatment with surgery and/or local radiation therapy. Two men are described in whom radiotherapy-relapsing cutaneous B-cell lymphomas were successfully treated with the monoclonal anti-CD20 antibody rituximab. Both patients had a complete response with no recurrence at follow-up at 17 and 24 months for the large B-cell lymphoma of the leg and the follicle centre cell lymphoma, respectively. These are two of the few cases in the literature showing that rituximab is an effective and well-tolerated treatment for radiotherapy-relapsing primary cutaneous B cell lymphoma.

A chiroselective peptide replicator.

The origin of homochirality in living systems is often attributed to the generation of enantiomeric differences in a pool of chiral prebiotic molecules, but none of the possible physiochemical processes considered can produce the significant imbalance required if homochiral biopolymers are to result from simple coupling of suitable precursor molecules. This implies a central role either for additional processes that can selectively amplify an initially minute enantiomeric difference in the starting material, or for a nonenzymatic process by which biopolymers undergo chiroselective molecular replication. Given that molecular self-replication and the capacity for selection are necessary conditions for the emergence of life, chiroselective replication of biopolymers seems a particularly attractive process for explaining homochirality in nature. Here we report that a 32-residue peptide replicator, designed according to our earlier principles, is capable of efficiently amplifying homochiral products from a racemic mixture of peptide fragments through a chiroselective autocatalytic cycle. The chiroselective amplification process discriminates between structures possessing even single stereochemical mutations within otherwise homochiral sequences. Moreover, the system exhibits a dynamic stereochemical 'editing' function; in contrast to the previously observed error correction, it makes use of heterochiral sequences that arise through uncatalysed background reactions to catalyse the production of the homochiral product. These results support the idea that self-replicating polypeptides could have played a key role in the origin of homochirality on Earth.

Observational study of maternal anthropometry and fetal insulin.

AIMS: To examine the relation between maternal body fat and fetal metabolism. METHODS: In this observational study, cord blood samples were collected from 60 infants of healthy women for the measurement of insulin and C peptide concentrations. Maternal weight, height, body mass index (BMI) and body composition (skinfold thickness measurements and bioelectrical impedance) were assessed at 13-15 weeks of gestation. Twenty five of the volunteers agreed to have a 75 g oral glucose tolerance test at 28-31 weeks of gestation. RESULTS: Positive correlations were observed with both cord insulin or C peptide concentrations and maternal early pregnancy BMI (r=0.44, p=0.002 and r=0.33, p=0.008, respectively). There was no significant correlation between cord insulin or C peptide concentrations and birthweight or birth weight centiles. CONCLUSION: Maternal BMI could be a predictor of fetal cord insulin concentration.

Epidemiology and mortality of burns in Tehran, Iran.

In order to assist with the prevention of burn injuries the epidemiology of burns in Tehran was investigated. In a retrospective study, 1239 files of patients who were living in Tehran and were injured between March 1994 and March 1995 were studied. Sixty-three per cent of patients were male and 37 per cent were female (age range, 1 month to 93 years). The highest incidence of burns was in the 16-25 age group (30/100000). Patients with below 40 per cent of burned surface constituted 52.5 per cent of injuries. The most common cause of burns was kerosene accidents. The most common cause of burns in children was boiling water. In terms of social class the highest rate of burns was observed among illiterate people (burn rate (BR) 39/100000). The mean length of hospitalization was 12 days. Of the 1239 cases, 737 patients died. The mortality rate was 51 per cent in males and 69 per cent in females. The mean body surface area burned was higher in females. The mortality rate was higher and the length of hospitalization was shorter in comparison with other studies in other countries.

Evaluating the role of Th0 and Th1 clones in autoimmune thyroid disease by use of Hu-SCID chimeras.

To study the role of Th0 and Th1 cells in autoimmune thyroid disease, thyroid tissues from patients with Graves' disease (GD), Hashimoto's thyroiditis (HT), and colloid nodular disease were xenografted into SCID mice, followed by ip injection of peripheral blood mononuclear cells (PBMC), T cell lines, and T cell clones (TCC). The antigen-specific TCC reactive to TSH receptor (TSH-R), thyroid peroxidase (TPO), or thyroglobulin (Tg), and their respective peptides, were classified into Th0 (secreting IL-4 and/or IL-5 and IFN-gamma) and Th1 (secreting IFN-gamma) according to their cytokine profile. Engraftment of autologous or HLA-matched allogeneic CD4+ thyroid-specific clones with Th0 or Th1 phenotypes induced the production of total IgG and thyroid-specific autoantibodies by B cells present in xenografted thyroid tissues. TSH-R-specific clones mainly enhanced thyroid-stimulating antibodies (TSAb) production, while clones reactive to TPO and Tg increased the synthesis of TPO and Tg autoantibodies. Total IgG production, but not TSAb, was also stimulated by PBMC and TSH-R lines. TSAb correlated with the viability and hyperplasia of thyroid follicles, but not with the serum T3 levels, which were normal. Thyroid tissue viability was maintained or increased by antigen-specific Th0 clones, and decreased by Th1 clones reactive to TSH-R or TPO. Thyroid lymphocytic infiltration was variable; however, Th0 and Th1 clones from HT patients caused high degree of lymphocytic infiltration compared to the control groups. These results demonstrate for the first time that T cells clones reactive to specific epitopes of TSH-R, TPO, or Tg can generate antibody-mediated and/or cell-mediated responses in the xenografted thyroid tissue microenvironment. Such effects depend on clonal specificity, HLA class II restriction, and cytokine profile of the clone. Th0 clones reactive to TSH-R stimulate both total IgG production and TSAb in SCID mice engrafted with thyroid tissue from GD patients. Th0 and Th1 clones specific for TPO and Tg also function as helper T cells, stimulating total IgG synthesis and autoantibodies against TPO and Tg. Th1 clones may also cause tissue destruction in GD and HT.

Thyrotropin-receptor and thyroid peroxidase-specific T cell clones and their cytokine profile in autoimmune thyroid disease.

We studied the cytokine profile and the immune responses to thyroid antigens of specific T cell clones (TCC) isolated from patients with Hashimoto's thyroiditis (HT) and Graves' disease (GD). Antigen-specific TCC were reactive to thyroid peroxidase (TPO), thyroglobulin (Tg) or human recombinant TSH-receptor extracellular domain (TSH-R), and/or their respective peptides. Of the 43 clones derived from HT patients, 65% were reactive to TPO, and 59% of the 32 clones derived from GD patients were reactive to TSH-R. TPO epitopes 100-119 and 625-644 were recognized by 75% of HT-derived clones, whereas TSH-R epitopes 158-176, 207-222, and 343-362/357-376 were recognized by 85% of GD-derived TCC. The TCC were classified according to their cytokine profile into T helper cell (Th)0 [secreting interleukin (IL)-4, IL-5, interferon (IFN)-gamma], Th1 (secreting IFN-gamma) and Th2 (secreting IL-4 and/or IL-5). Tumor necrosis factor-beta and IL-10 were produced by all subsets. The specific TCC were predominantly Th1-like cells in HT, and were Th0- and Th1-like cells in GD. Fifty three percent of Th0 clones were derived from GD patients and were reactive to TSH-R, whereas 50% of Th1 clones were derived from HT patients and were reactive to TPO or Tg. Most Th2 clones (82%) were reactive to TPO and were established from peripheral blood. All these clones produced IL-5, and 64% produced IL-4 and IL-10. Interestingly, IFN-gamma was highly produced by TPO- or Tg-specific clones established from HT thyroid tissue. These results confirm at the clonal level our previous studies regarding T cell epitopes on TPO and TSH-R molecules and support the concept that immunodominant T cell epitopes are located on amino acid residues 100-119 and 625-644 of TPO in HT and amino acid residues 158-176, 207-222 and 343-362/357-376 of TSH-R in GD. Our studies also demonstrate that thyroid-specific T cells can be classified into Th0, Th1, and Th2 subsets. TPO- or Tg-specific clones with Th1 phenotype appear to be involved in the pathogenesis of HT, mediating thyroid tissue destruction, whereas TSH-R clones with Th0 phenotype may induce thyroid-stimulating autoantibodies in GD.

Interleukin-2 associated linear IgA bullous dermatosis.

Linear IgA bullous dermatosis (LABD) in adults is characterized by subepidermal bullae associated with a linear deposition of IgA at the basement membrane zone. Its cause is unclear, although it appears to have an immune-mediated basis. The development of LABD in a cancer patient undergoing immunotherapy has been described in the French literature. We describe a similar case of LABD arising in a patient while undergoing interleukin-2 immunotherapy for renal cell carcinoma.

Identification of genes encoding for peptide synthetases in the gram-negative bacterium Lysobacter sp. ATCC 53042 and the fungus Cylindrotrichum oligospermum.

Genes encoding for the multifunctional peptide synthetases lysobactin synthetase and peptolide SDZ 214-103 synthetase were identified by hybridization of genomic libraries with oligonucleotides derived from consensus motifs of various genes encoding for delta-(L-alpha amino-adipoyl)-L-cysteinyl-D-valine (ACV) synthetases and gramicidin S synthetase. The sequence of subcloned gene fragments revealed core motifs and a modular structure typical for the family of peptide synthetase genes. A fragment of 4.6 kb of the lysobactin synthetase gene was sequenced and one amino acid activating module was localized. The cloning of lysobactin synthetase was verified by marker-exchange mutagenesis and the lysobactin minus phenotype of the mutant. The sequenced 3.1 kb fragment of peptolide SDZ 214-103 synthetase contained parts of two modules and was highly homologous to corresponding regions of module 6 and 7 of cyclosporin synthetase. Therefore, the localized modules may activate the amino acids threonine and glycine.

Proliferative responses of T-cells to thyroid antigens and synthetic thyroid peroxidase peptides in autoimmune thyroid disease.

We studied the immune responses of 33 patients with autoimmune thyroid disease (AITD; including 17 with Hashimoto's thyroiditis and 16 with Graves' disease), 5 patients with non-AITD, 12 control subjects (CS), and 2 subjects with a family history of autoimmunity to the main thyroid antigens. These antigens included thyroid peroxidase (TPO), thyroglobulin (Tg), TSH receptor (TSH-R), and 13 overlapping TPO peptides. T-cell lines (TCL) were isolated from peripheral blood mononuclear cells (PBMC) after incubation with TPO, Tg, or a protein derivative of tuberculin (PPD). PBMC and TCL were used in a 3- to 5-day microproliferation assay. Peripheral lymphocytes from most AITD patients responded with a stimulation index of 3 or more to TPO, Tg, and/or TSH-R (60-88%) as well as to two or more TPO peptides. Lymphocytes from 3 of 5 patients with non-AITD and 2 subjects with a family history of autoimmunity were also reactive to thyroid antigens. TPO TCL showed a high proliferative response to TPO and its peptides, whereas Tg TCL were less reactive and PPD TCL were nonreactive to these antigens. Six of the 13 peptides tested produced highly significant stimulation in PBMC (CS, 0-17%; AITD, 60-92%) and TPO TCL (73-91%). The amino acid sequences of these putative epitopes were located in TPO regions 100-119, 211-223, 261-275, 420-434, 625-644, and 882-901. These results demonstrate T-cell responses to the main thyroid antigens, including TPO, Tg, and TSH-R, and confirm the heterogeneity of TPO T-cell epitopes in patients with AITD. Amino acid residues 100-119, 420-434, 625-644, and 882-901 are the most common sites recognized by TPO TCL, indicating that they may be immunogenic epitopes in AITD.

[Long-term follow-up of chronic hepatitis C after treatment with recombinant interferon alpha-2a]. / Langzeitbeobachtung der chronischen Hepatitis C nach Behandlung mit rekombinantem Interferon alpha-2a.

As part of a multicenter randomized study 40 patients with chronic hepatitis C (HCV)-infection, 28 kryptogenic and 12 posttransfusional, were treated with recombinant interferon alfa (IFN alpha-2a) for 1 year in a dosage of 3 x 3 Mio. units per week versus dosis escalation after 8 and 16 weeks in serological non-responders. 36 of the 40 patients were followed over 3 years. The rate of patients with normalization of aminotransferases was 42% after two months of therapy, 28% at the end of treatment, 28% after 1 year and 23% after 3 years of follow-up. The polymerase chain reaction (PCR) for detection of HCV-RNA became negative after two months of treatment in 73%, at the end of therapy in 63%, after 1 year follow-up in 63% and after 3 years in 35%. All patients with persisting remission maintained HCV-RNA negative. Dosis escalation was realized in 8 patients without increase of responder rate. Antibodies against IFN alpha-2a developed in 4 (10%) patients without remarkable influence on the IFN-effect. Histological improvement at the end of treatment was observed in 61% including all patients with serological remission. The data support the prognostic relevance of the course of aminotransferases. If aminotransferases are not normalized during the first two months the treatment can be terminated. Persisting normalization of aminotransferases during 1 year after therapy and negative HCV-PCR result indicate maintaining remission.

Management of hand dermatitis.

Ill-defined endogenous factors are important in many cases of hand dermatitis; however, these factors are difficult to identify, and, ultimately, there is little the physician can do to alter a patient's constitution. Because of this, therapy of hand dermatitis focuses on identifying exogenous factors and avoiding these where possible. Steroids are invaluable, but gentle skin care remains the basis of treating hand dermatitis. Recalcitrant hand dermatitis, especially potential occupational cases, requires the involvement of a dermatologist.

Immunocytochemical localization of androgen receptors in human skin using monoclonal antibodies against the androgen receptor.

Androgen receptors were localized in cryostat sections of human skin using monoclonal antibodies to the human androgen receptor. Bound antibodies were detected using biotinylated rabbit anti-rat IgG, peroxidase-conjugated streptavidin, and diaminobenzidine as chromogen. In the neonatal foreskin, antibody to androgen receptor bound to keratinocytes in the epidermis and to fibroblasts and vascular endothelial cells in the dermis. Immunohistochemical staining was stronger in nuclei than in cytoplasm. This staining was specific, because there was no significant staining when antibody to the androgen receptor was replaced with IgG from nonimmunized rats or with buffer, or when antibody to androgen receptor was incubated, prior to immunostaining, with a trp E-human androgen-receptor fusion protein used as immunogen. Incubation of androgen receptor antibody with trp E alone did not affect staining. Androgen-receptor antibody also bound to keratinocytes, fibroblasts, and endothelial cells in skin from adult men and women. Skin from the scalp, nose, lip, back, and chest gave positive staining for androgen receptor. Antibody to androgen receptor also bound to the coil and ductal cells of eccrine glands, external root sheath of hair follicles, epithelium in the hair bulb, dermal papilla cells, and sebocytes. There was no significant binding to adipocytes, collagen, or stratum corneum. These results show that androgen receptor is present in cells that are known to be targets for androgens and also in cells in which the biologic effects of androgens are yet to be characterized.