Electrochemical aptasensors for contaminants detection in food and environment: Recent advances.

The growing number of contaminants requires the development of new analytical tools to meet the increasing demand for legislative actions on food safety and environmental pollution control. In this context, electrochemical aptamer-based sensors appear promising among all biosensors because they permit multiplexed analysis and provide fast response, sensitivity, specificity and low cost. The aim of this review is to give the readers an overview of recent important achievements in the development of electrochemical aptamer-based biosensors for contaminant detection over the last two years. Special emphasis is placed on aptasensors based on screen-printed electrodes which show a substantial improvement of analytical performances.

Acetamiprid multidetection by disposable electrochemical DNA aptasensor.

In this work, we propose an electrochemical DNA aptasensor for sensitive multidetection of acetamiprid based on a competitive format and disposable screen-printed arrays. To improve the sensitivity of the aptasensor, polyaniline film and gold nanoparticles were progressively electrodeposited on the graphite screen-printed electrode surface by cyclic voltammetry. Gold nanoparticles were then employed as platform for thiol-tethered DNA aptamer immobilization. Different acetamiprid solutions containing a fixed amount of biotinylated complementary oligonucleotide sequence by DNA aptasensor arrays were analyzed. Streptavidin-alkaline phosphatase conjugate was then added to trace the affinity reaction. The enzyme catalyzed the hydrolysis of 1-naphthyl phosphate to 1-naphthol. The enzymatic product was detected by differential pulse voltammetry. A decrease of the signal was obtained when the pesticide concentration was increased, making the sensor work as signal off sensor. Under optimized conditions by testing key experimental parameters, a dose-response curve was constructed between 0.25 and 2.0µM acetamiprid concentration range and a limit of detection of 0.086µM was calculated. The selectivity of the aptasensor was also confirmed by the analysis of atrazine pesticide. Finally, preliminary experiments in fruit juice samples spiked with acetamiprid were also performed.

Urticating Hashimoto-Pritzker Langerhans cell histiocytosis.

Red-brown papules developing during the neonatal period may present a diagnostic dilemma. The Darier sign has been a reliable feature in the diagnosis of mastocytosis. However, the cutaneous infiltrate of Hashimoto-Pritzker Langerhans cell histiocytosis (LCH) may contain a large number of mast cells, leading to confusion both clinically and histologically. We report an infant who developed red-brown papules of Hashimoto-Pritzker LCH during the neonatal period and presented with a positive Darier sign and acute urticaria.

Silicone auricular prosthesis.

Skin cancer surgery of the ear may result in a large defect of skin and cartilage requiring a staged flap procedure for reconstruction. An alternative to surgical reconstruction is the creation of a silicone auricular prosthesis. These prostheses provide a cost-effective and cosmetically acceptable means of camouflage for patients who decline or postpone surgical reconstruction. The process of creating a silicone auricular prosthesis is discussed.

Spitz nevus or melanoma?

Spitz nevi are benign melanocytic neoplasms of children and young adults that can be exceedingly difficult to distinguish from malignant melanomas. Although a nearly definite diagnosis can be made in most cases, the histological distinction between Spitz nevi and melanomas is equivocal in about 6% to 8% of cases. In those cases, and perhaps even with presumed benign Spitz nevi, clear surgical margins are desirable. The most helpful differentiating features of Spitz nevi are patient age, sharp demarcation, symmetry, maturation of melanocytes at the base, and epithelial hyperplasia. None of these criteria are completely reliable, and multiple other criteria must be considered as well.

Dermatopathologic advances in clinical research. The expression of antibody to CD34 in mucocutaneous lesions. off.

The human progenitor cell antigen, CD34, is selectively expressed in most hematopoietic colony-forming cells from normal human bone marrow, and in a significant proportion of acute leukemias. Within the dermis, CD34 is normally expressed by endothelial cells, dendritic cells, and the spindle-shaped cells around adnexal structures. Benign and malignant vascular lesions, adnexal tumors differentiating toward the external root sheath (trichilemmomas and pilar tumors), specific benign soft tissue tumors (spindle cell lipoma and solitary fibrous tumors), and many of the gastrointestinal stromal tumors uniformly express CD34 antigen. CD34 expression is also often present in benign tumors of neural origin; however, it is less consistently present in malignant peripheral nerve sheath tumors.

Oral melanoma: diagnosis and treatment.

Melanoma of the mouth is rare, most commonly occurring on the upper jaw of patients older than 50 years. Because of a frequent delay in diagnosis, the tumors are often diagnosed after they are deeper than the average cutaneous melanoma. Hence, the prognosis tends to be poor. Surgery is the mainstay of treatment, but often it is difficult because of anatomic restraints. Although melanoma is classically not very radiosensitive, occasional patients have had a good response to radiation therapy, sometimes with temporary palliation. Other treatment modalities are similar to those used for cutaneous melanoma. Immunotherapy, including interferon, has been used. Chemotherapy has a low response rate.

False-positive polymerase chain reaction results for human papillomavirus in lichen planus. Potential laboratory pitfalls of this procedure.

BACKGROUND: The polymerase chain reaction (PCR) is a common tool in laboratory evaluation of tissue samples. It has been particularly useful in testing for nucleic acids of infectious organisms implicated in the pathogenesis of cutaneous diseases. OBJECTIVE: Our purpose was to evaluate archival biopsy material (paraffin-embedded) of lichen planus for human papillomavirus (HPV) DNA with PCR and in situ hybridization (ISH). METHODS: Tissue sections were obtained from 13 specimens of lichen planus and 10 control tissues. Standard methods for PCR and ISH were used to evaluate the presence of HPV DNA. RESULTS. Initial PCR results demonstrated HPV DNA in 11 of 13 specimens and in none of the control tissue. However, testing for specific HPV types revealed nucleic acid contamination. ISH was negative in all specimens. CONCLUSION: Accurate evaluation of tissue with PCR is difficult because of the procedure's profound sensitivity. Positive results reported in the literature should be viewed with caution. Potential causes for false-positive and false-negative results should be considered.

Pleomorphic basal cell carcinoma.

BACKGROUND: A variant of basal cell carcinoma (BCC) with scattered large, pleomorphic cells has previously been reported as "basal cell epithelioma with giant tumor cells" and "basal cell carcinoma with monster cells." OBJECTIVE: Our purpose was to describe the clinical, histologic, and DNA ploidy findings in BCCs with these cytologic features. METHODS: Nineteen pleomorphic BCCs from 15 patients were prospectively collected, and other BCCs in these patients were retrospectively reviewed by light microscopy. One lesion was recurrent. Seven of the pleomorphic BCCs and one nonpleomorphic BCC were studied by image analysis. RESULTS: These pleomorphic BCCs ranged from 2.8 to 12.5 mm in greatest diameter and were most commonly located on the head and neck. Five BCCs were present on the face and scalp of a patient with basal cell nevus syndrome. There have been no subsequent recurrences of the pleomorphic BCCs (follow-up from 3 to 32 months; median, 20 months). All 19 pleomorphic BCCs displayed characteristic features of BCC: peripheral palisading, stromal retraction, mucin production, and apoptosis. All 19 also showed huge pleomorphic mononucleated and multinucleated giant tumor cells. The nuclei of these large cells were often hyperchromatic with prominent nucleoli and abundant cytoplasm, and occasionally with intranuclear cytoplasmic protrusions. In addition, there were frequent and atypical mitoses in 47% of the cases. All pleomorphic BCCs studied by cell image analysis of formalin-fixed, paraffin-embedded tissue were aneuploid. The DNA content of the giant tumor cells was not a multiple of a single DNA value. CONCLUSION: Pleomorphic BCCs clinically present as typical BCCs. Despite their striking focal cellular atypia, these lesions seem to behave as ordinary BCCs.

Incidental epidermolytic hyperkeratosis.

Epidermolytic hyperkeratosis is the distinctive histopathologic change that has been described as the main feature of bullous congenital ichthyosiform erythroderma and as an incidental finding in other cutaneous disorders. We retrospectively evaluated our cases of incidental epidermolytic hyperkeratosis over a 5-year period, and reviewed the conditions that have been associated with incidental epidermolytic hyperkeratosis. We identified 21 individuals (14 men and seven women), ranging in age from 3 to 87 years, in whom incidental epidermolytic hyperkeratosis was found. Lesions in which the pathologic changes of incidental epidermolytic hyperkeratosis have been reported include dermal fibrohistiocytic lesions, epithelial neoplasms, hereditary disorders, inflammatory conditions, and melanocytic neoplasms. The histogenesis of incidental epidermolytic hyperkeratosis remains to be determined.

Malignancy in Maffucci's syndrome.

Maffucci's syndrome is characterized by multiple enchondromas and subcutaneous hemangiomas. These tumors typically present in early childhood and may lead to significant skeletal deformities. Malignant transformations are a common feature of this syndrome and have been reported in approximately 30% of reported cases, with chondrosarcomas being the most common.

Acral melanocytic neoplasms: a histologic analysis of 158 lesions.

BACKGROUND: Acral nevi occasionally demonstrate pagetoid spread of melanocytes. This feature may be of considerable concern because it is commonly associated with melanoma. Other features of melanoma must be assessed to accurately classify these neoplasms as benign. OBJECTIVE: We examined acral melanocytic lesions, benign and malignant, to evaluate their features. METHODS: A retrospective analysis during 3 years was performed on 158 acral pigmented lesions diagnosed by the dermatopathology service. Blue nevi, intradermal nevi, lentigines, and Spitz nevi were excluded. The specimens were divided into three groups: benign nevi, benign nevi with pagetoid spread, and melanoma. They were evaluated for circumscription, symmetry, papillary dermal fibroplasia, bridging between rete ridges, inflammatory infiltrate, pagetoid spread, cytologic atypia, and mitotic activity. RESULTS: Most lesions (60%) were compound nevi and 84% were from the foot. Ten specimens were melanomas (6%) and 28 (18%) were nevi with architectural disorder. Pagetoid spread of melanocytes, often minimal, was found in 57 benign lesions. However, these nevi did not demonstrate the degree of pagetoid spread, cellular atypia, inflammation, and asymmetry found in malignant lesions. CONCLUSIONS: The presence of pagetoid spread of melanocytes is common in otherwise benign acral nevi. Other parameters of malignancy in these neoplasms must be evaluated to determine their biologic potential.

Skin lesions of the spinal axis and spinal dysraphism. Fifteen cases and a review of the literature.

OBJECTIVE: To catalog the paraspinal skin lesions of early childhood that are associated with occult spinal dysraphism. RESEARCH DESIGN: Retrospective review of a series of patients. SETTING: Tertiary care referral center. PATIENTS: Fifteen patients who had significant paraspinal skin lesions were identified from the personal files of the authors who saw them. RESULTS: The skin lesions included various combinations of hyperpigmentation, hypopigmentation, hypertrichosis, acrochordons, dimples, lipomas, hemangiomas, or teratomas. Not all lesions were evaluated with the same tests, which included plain roentgenography, ultrasonography, myelography, computed tomography, and magnetic resonance imaging. Of the 15 patients, six had spinal anomalies, eight had no apparent spinal dysraphism, and one had insufficient results of the evaluation to assess the spinal column. CONCLUSIONS: Early recognition of paraspinal skin lesions is essential to prevent neurologic damage. Urinary or fecal incontinence, recurrent urinary infections, muscle atrophy, foot deformities, weakness, pain, or decreased sensation in the lower extremities may eventually develop in these patients. Magnetic resonance imaging appears to be the single best screening test for dysraphism.

Cutaneous collision tumors. An analysis of 69 cases and review of the literature.

The association of two different neoplasms in the same biopsy specimen is not uncommon and has been reported by numerous authors. Some associations may result from involvement of related cell types, however, most are serendipitous. Our study attempted to investigate the nature and types of contiguous or "collision" tumors seen in our dermatopathology service. A retrospective evaluation of approximately 40,000 cutaneous biopsies was performed, yielding 69 examples of collision tumors. Excluded were biphasic lesions of the same cell type (e.g., basosquamous carcinomas or combined nevi). Results were as follows: The most common combinations included basal cell carcinoma and nevus (14), basal cell carcinoma and seborrheic keratosis (8), nevus and seborrheic keratosis (14), actinic keratosis and nevus (7), and basal cell carcinoma and neurofibroma (4). Adnexal tumors were found combined with other neoplasms in four patients and blue nevi were noted in three additional tumors. We believe that most of these represent the presence of two or more common lesions juxtaposed by coincidence. However, certain combinations are of similar cell lineages or contain a relatively uncommon tumor and may indicate a possible link between the different cell types.

Keratinocyte transglutaminase expression varies in squamous cell carcinomas.

Type I transglutaminase (TGase I, keratinocyte or particulate transglutaminase) is a 92-kilodalton (kDa) protein expressed in abundance in cultured keratinocytes and in the hyperproliferative skin disorder psoriasis. To determine the expression of TGase I protein and mRNA, we studied tissue and established squamous carcinoma lines derived from different sources. Immunohistochemistry and Western blotting were used to detect TGase I protein with the B.C1 mouse monoclonal antibody. Only well-differentiated, skin-derived squamous carcinomas stained for TGase I. However, a precocious pattern of expression was seen overlying less-differentiated tumors. Compared to cultured human keratinocytes, squamous cell carcinoma (SCC) had many times less to 7.8 times more TGase I protein, greatest in the two most differentiated tumor lines 14-83 and ME-180. TGase I mRNA levels ranged from 0.010 to 0.00004 pg/microgram total RNA by reverse transcriptase-polymerase chain reaction using an internal standard. Protein expression correlated with mRNA levels in most SCC lines. When a human TGase I promoter was isolated and used to study genomic DNA, SCC1-83 was shown to have unique restriction enzyme fragments, including one indicative of methylation differences, also present within DNA from the KB line. These studies suggest that transcriptional control of TGase I gene expression in squamous carcinomas may be influenced both by cis elements in the promoter and by the degree of tumor squamous differentiation.

Emergence of leprosy in a patient with mycosis fungoides.

A patient with mycosis fungoides that had progressed to tumor stage responded to chemotherapy and electron beam treatment, but 6 years later a peripheral neuropathy, extensive plaques, erythroderma, and enlarged pinnae containing acid-fast organisms developed while he was being treated with photopheresis. The skin lesions cleared with administration of rifampin and dapsone, but a reversal reaction biopsy specimen showed features of both mycosis fungoides and leprosy. This case raises the question of whether there may be an association between mycosis fungoides and leprosy.