Biomedical subjects
Thomas Petit
Publications and source records attributed to Thomas Petit.
[The gastric antrum: a rare primitive location of a gastrinoma within a type I multiple endocrine neoplasia].
We report the case of an 18-year-old man, with no previous medical history, presenting with recurrent hemorrhagic duodenal ulcers revealing a Zollinger-Ellison syndrome. The initial diagnosis of sporadic gastrinoma of the antrum associated with satellite lymph nodes led to surgical treatment. The evolution of clinical and secretory tests associated with the outbreak of a primary hyperparathyroïdism demonstrated that the patient had a type I multiple endocrine neoplasia. To our knowledge, this is the first described case of primitive gastrinoma of the antrum occurring in a type I multiple endocrine neoplasia.
Physiological and genome-wide transcriptional responses of Saccharomyces cerevisiae to high carbon dioxide concentrations.
Physiological effects of carbon dioxide and impact on genome-wide transcript profiles were analysed in chemostat cultures of Saccharomyces cerevisiae. In anaerobic, glucose-limited chemostat cultures grown at atmospheric pressure, cultivation under CO(2)-saturated conditions had only a marginal (<10%) impact on the biomass yield. Conversely, a 25% decrease of the biomass yield was found in aerobic, glucose-limited chemostat cultures aerated with a mixture of 79% CO(2) and 21% O(2). This observation indicated that respiratory metabolism is more sensitive to CO(2) than fermentative metabolism. Consistent with the more pronounced physiological effects of CO(2) in respiratory cultures, the number of CO(2)-responsive transcripts was higher in aerobic cultures than in anaerobic cultures. Many genes involved in mitochondrial functions showed a transcriptional response to elevated CO(2) concentrations. This is consistent with an uncoupling effect of CO(2) and/or intracellular bicarbonate on the mitochondrial inner membrane. Other transcripts that showed a significant transcriptional response to elevated CO(2) included NCE103 (probably encoding carbonic anhydrase), PCK1 (encoding PEP carboxykinase) and members of the IMD gene family (encoding isozymes of inosine monophosphate dehydrogenase).
[Mixed tumor or myoepithelioma of the skin? Histologic and immunohistochemical features].
Mixed tumor, first reported in the parotid gland, is formed from the proliferation of epithelial and myoepithelial cells in a mesenchymatous stroma. We report the case of a woman hospitalized for a subcutaneous nodule of the thigh, characterized by a fast increased in size in 8 months. Microscopic analysis showed a proliferation of grouped and isolated spindle cells, without atypia or mitotic features. Few tubular features were noted. Stroma was hyalinized or myxoid. Neoplastic cells displayed immunohistochemical positivity with smooth muscle actin, keratin and S-100 protein. This neoplasm appeared mesenchymatous. The diagnosis was mixed tumor with a predominant myoepithelial component. This case underlines the difficulties encountered in defining this neoplasm. Some authors consider that myoepithelioma is a monophasic variant of mixed tumor; others consider that myoepithelioma is different from mixed tumor because its is more aggressive prognosis. The evolution of our case suggests that a myoepithelial differentiation should be a ma of poor prognosis.
[Basocellular carcinoma that everyone's talking about].
Explore the source record for details and available documents.
[Solitary cutaneous infantile myofibromatosis].
Infantile myofibromatosis is the most frequent fibromatosis in childhood. It is a benign proliferation of fibroblasts and myofibroblasts. This case report concerns a newborn who presented at birth with a purple cutaneous nodule on the scalp. Surgical excision was performed at the age of 16 months. Infantile myofibromatosis was diagnosed on histology. Infantile Myofibromatosis (IMF) was first described by Enzinger in 1981. Three types can exist. Solitary MFI, the most frequent, is a solitary lesion, cutaneous/subcutaneous, osseous or involving soft tissues. Multicentric disease is characterized by multiple locations and generalized form by visceral involvement. Morphological features are identical in all types. The histological diagnosis relies on the identification of two separate components, a fascicular myofibroblastic pattern at the periphery with a hemangiopericytoma like pattern in the centre. Both components are positive for alpha-smooth muscle actin. Atypia, or mitotic activity, are not observed usually but features of intravascular growth can be seen in the centre of the lesion. Infantile MF carries a good prognosis when solitary but death frequently occurs in generalized MF with visceral involvement.
Comparative genotyping of the Saccharomyces cerevisiae laboratory strains S288C and CEN.PK113-7D using oligonucleotide microarrays.
To analyse the reliability and accuracy of genotype analysis with high-density oligonucleotide microarrays, this method and other experimental approaches were used to analyse genomic DNA of two popular Saccharomyces cerevisiae laboratory strains. S288C was used for systematic sequencing of 'the' S. cerevisiae genome; CEN.PK113-7D is a popular strain for physiological studies and functional genomics. Random amplified polymorphic DNA, electrophoretic karyotyping and microarray analysis all indicated a high level of sequence similarity between the two strains. In the microarray analysis, as few as 288 (4.5%) of the ca. 6300 represented yeast genes were identified that yielded significantly different hybridisation intensities between the two strains. These could be classified as amplified, absent, or with sequence polymorphism in CEN.PK113-7D compared to S288C. A detailed analysis focused on the subset of 25 genes called absent in CEN.PK113-7D. Among these absent genes, 17 were clustered together on five chromosomes, mainly in subtelomeric regions. Thorough analysis of these regions by polymerase chain reaction (PCR) and restriction fragment length polymorphism confirmed the absence of these genes in CEN.PK113-7D. Surprisingly, three of these regions were not smaller in CEN.PK113-7D chromosomes, indicating that they may harbour unidentified and potentially new sequences. In addition, eight genes called absent by the microarrays were scattered over the chromosomes. Using diagnostic PCR most of these genes were actually found to be present in CEN.PK113-7D, but after sequencing were found to differ significantly at the DNA level from S288C, explaining the poor hybridisation to the arrays. Our results indicate that DNA microarrays are a powerful tool for determining genotypic similarity between different yeast strains. However, to obtain meaningful information at the individual gene level, this method should be backed up by additional techniques.
[Pilomatrix carcinoma: histologic and immunohistochemical features. Two studies].
Malignant pilomatricoma is a rare malignant hair follicle tumor, that was initially described in 1980. Histologically, it shares common features with the more frequent, which benign pilomatricoma, makes its diagnosis difficult. It is a deep dermis-hypodermis epithelial tumor, well circumscribed, with no relation with the epidermis. It is composed of nodular structures with rows of basaloid cells in their periphery, as well as focal necrosis and mummified "ghost" cells in their central parts. Immunohistochemistry is of little value and can not confirm malignancy. The diagnosis remains essentially morphological. Histological examination must stress on the evaluation of the degree and extent of infiltration of the surrounding tissues, the degree of necrosis, the presence of atypical mitotic figures, and the presence or not of peri-neural or vascular invasion. Surgical wide resection is the recommended treatment. It reduces the risk of local recurrence by 50%. Malignant pilomatricoma carries a high risk of metastases to the bones, lungs, and lymph nodes. No feature is specific to confirm wether a malignant pilomatricoma arises de novo, or whether it is a malignant transformation of a pre-existing benign pilomatricoma.
[Acute ulcerative colitis in a patient treated with rofecoxib who took aspirin as self-medication].
Explore the source record for details and available documents.
[CD-ROM in pathology: another teaching tool].
Explore the source record for details and available documents.
[A polyposis which is not out of breath!].
Explore the source record for details and available documents.
[Pigmented lesions of the vulva: histological features].
The vulva is an anatomical and histological combination of cutaneous and mucous components. It is the site of various pigmented lesions, in 10 to 12% of white women, often of unknown etiology. The clinical features are polymorph, non-specific, thus requiring a biopsy. Histological analysis helps to rule out the diagnosis of melanoma, which frequently leads to mutilating surgical treatment and which has an unfavorable prognosis. We present a review of the anatomical and histological characteristics of the normal vulva and of the process of melanogenesis. In addition, the histological criteria that enable the etiological diagnosis of vulvar pigmented lesions are presented. Some of these lesions are tumoral, melanocytic or non-melanocytic, isolated or related to a general pathology; others, non-tumoral, related to inflammatory, immunological, hormonal, or paraneoplasic mechanisms, can be manifestations of systemic diseases. Biopsy specimen analysis and anatomo-clinical correlation are essential for the appropriate diagnosis and the treatment of these lesions.
[A painful swelling of the nipple].
Explore the source record for details and available documents.
Inflammatory vitiligo-like macules that simulate hypopigmented mycosis fungoides.
Two cases of an inflammatory vitiligo-like condition that simulated mycosis fungoides are reported. Both patients presented acquired hypopigmented macules sharply limited by an erythematous and papular border. The clinical aspect was suggestive of inflammatory vitiligo. Mycosis fungoides was suspected on skin specimens showing a dense band-like lymphocytic infiltrate with discrete nuclear atypias and marked exocytosis. This infiltrate was made of CD3 positive lymphocytes. CD8 positive lymphocytes were numerous in one case, few in the other. There was a loss of melanocytes in the lesional skin and absence of dominant T-cell clones in both cases. No repigmentation was observed after PUVA or local chemotherapy. The authors emphasized that erythematous and papular borders surrounding hypopigmented macules, CD8 positive lymphocytic infiltrate, absence of T-cell clonal rearrangement are helpful to rule out mycosis fungoides.
Management of basal cell carcinoma in adults Clinical practice guidelines.
Explore the source record for details and available documents.