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Biomedical subjects

M L Mesa

Publications and source records attributed to M L Mesa.

18 recordsLinked to original sources
PubMed1999

Malignant spindle cell tumor arising in the mandible of a patient with florid osseous dysplasia.

Florid osseous dysplasia is a non-neoplastic condition of the alveolar processes of the jaws characterized by the replacement of multiple foci of bone by fibrous connective tissue, accompanied by gradual deposition of cementum, bone, or both. The lesions are not associated with inflammatory diseases of the dental pulp or periodontal tissues. In fully developed florid osseous dysplasia, there are multiple lobulated masses in the alveolar bone bilaterally in the mandible and sometimes in the maxilla. This is the first report of a malignancy originating within the jaws of a patient with florid osseous dysplasia. A spindle cell malignancy was diagnosed in the mandible of a 54-year-old black woman whose jaw was affected by florid osseous dysplasia bilaterally. Despite extensive surgery and radiotherapy, the patient died 20 months after diagnosis of the malignancy.

Fatal Outcome↗
PubMed1998

Phorbol esters down-regulate alpha-fetoprotein gene expression without affecting growth in fetal hepatocytes in primary culture.

The effects of phorbol esters (phorbol-12,13-dibutyrate, PDB) on alpha-fetoprotein expression and cell growth were assayed by using fetal hepatocytes in primary culture. PDB acts synergistically with epidermal growth factor (EGF) to specifically decrease alpha-fetoprotein (AFP) mRNA levels, without affecting the expression of other genes of the same family, such as albumin and Vitamin D-binding protein (DBP). This effect is PDB-dose dependent, maximal effects being at 10 ng/ml. The implication of protein kinase C (PKC) in this effect seems clear since bisindolylmaleimide (BIS), a specific PKC inhibitor, completely blocks the PDB effect on AFP expression. Nuclear run-on experiments show that the decrease in AFP mRNA levels is mainly due to an inhibition in the transcription rate of the gene. Determination of PKC activities shows that fetal hepatocytes contain mainly Ca(2+)-independent isoenzymes, which patterns of activation was not modified by EGF plus PDB treatment with respect to PDB treatment. We have found that MAPK and JNK activities, c-jun and c-fos mRNA levels and AP-1 binding activity are notably increased when cells are incubated with both EGF and PDB, PDB does not stimulate growth of fetal hepatocytes, measured either as [3H]-thymidine incorporation into DNA or by cell cycle analysis using flow cytometry. All these results suggest that activation of PKC may affect liver gene expression rather than cell growth in fetal hepatocytes.

Albumins↗
PubMed1996

Changes in rat liver gene expression induced by thioacetamide: protective role of S-adenosyl-L-methionine by a glutathione-dependent mechanism.

Chronic liver damage induced by thioacetamide (TAM) was accompanied by changes in the expression of genes related to growth (beta-actin) and function (albumin and haptoglobin) of the liver. Their messenger RNA (mRNA) levels increased during the first days after TAM administration, but 4 to 7 days after prolonged treatment with this drug, liver gene expression was considerable decreased. TAM-induced changes in albumin and beta-actin mRNA levels were prevented by cotreatment with S-adenosyl-L-methionine (SAM). We have investigated the possible involvement of glutathione in the protective mechanism of SAM. Firstly, we found that TAM treatment in the rat induced changes in liver glutathione disulfide (GSSG) levels, with a concomitant increase in the glutathione reductase enzymatic activity, these changes being abolished when animals were cotreated with TAM and SAM. Secondly, when rats were pretreated with buthionine sulfoximine (BSO), a glutathione synthesis inhibitor, before thioacetamide administration, the beneficial effect of SAM on liver gene expression was completely abolished. These results were confirmed by assaying the alanine transaminase serum activity, a parameter of liver injury. TAM-treated animals had increases in this serum enzyme, this effect being partially blocked by SAM. However, in BSO-pretreated rats, the protective effect of SAM was impaired. Taking together all these results, we propose a glutathione-dependent mechanism in the SAM protection against TAM hepatotoxicity in the rat.

Actins↗
PubMed1994

Clinical predictors of acute radiological pneumonia and hypoxaemia at high altitude.

Fast breathing has been recommended as a predictor of childhood pneumonia. Children living at high altitude, however, may breathe faster in response to the lower oxygen partial pressure, which may change the accuracy of prediction of a high respiratory rate. To assess the usefulness of clinical manifestations in the diagnosis of radiological pneumonia or hypoxaemia, or both, at high altitude (2640 m above sea level), 200 children aged 7 days to 36 months presenting to an urban emergency room with cough lasting less than seven days were studied. Parents were interviewed and the children evaluated using standard forms. The results of chest radiographs and pulse oximetry obtained after clinical examination were interpreted blind. Radiological pneumonia and haemoglobin oxygen saturation < 88% were used as 'gold standards'. One hundred and thirty (65%) and 125 (63%) children had radiological pneumonia and hypoxaemia respectively. Crepitations and decreased breath sounds were statistically associated with pneumonia, and rapid breathing as perceived by the child's mother, chest retractions, nasal flaring, and crepitations with hypoxaemia. The best single predictor of the presence of pneumonia is a high respiratory rate, although the results are not as good as those reported by other studies. A respiratory rate > or = 50/minute had good sensitivity (76%) and specificity (71%) for hypoxaemia in infants. Hypoxaemia had a good sensitivity and specificity for pneumonia mainly in infants (83% and 73%, respectively). Logistic regression analysis showed that decreased or increased respiratory sounds and crepitations were associated with pneumonia, and that hypoxaemia is the best predictor when auscultatory findings are excluded. These results suggest that some clinical predictors appear to be less accurate in Bogota than in places at lower altitude, and that pulse oximetry can be used for predicting pneumonia.

Acute Disease↗
PubMed1990

Differences between florid osseous dysplasia and chronic diffuse sclerosing osteomyelitis.

Florid osseous dysplasia (FOD) is confused in the literature with chronic diffuse sclerosing osteomyelitis. Two cases of each condition are presented to demonstrate the differences between them. In FOD, there are multiple lobulated sclerotic masses in several quadrants of the jaws, usually in black females. In some cases, the sclerotic masses are exposed to the oral cavity, resulting in a secondary osteomyelitis. Periapical cemental dysplasia is often found in association with FOD. Chronic diffuse sclerosing osteomyelitis is a primary inflammatory condition of the mandible. Patients have cyclic episodes of unilateral pain and swelling. The affected region of the mandible exhibits a diffuse opacity with poorly defined borders. Although women are affected more often than men, black persons are not particularly susceptible.

Adult↗
PubMed1988

Osteoporotic bone marrow defect: radiographic features and pathogenic factors.

The literature on osteoporotic bone marrow defect (OBMD) is reviewed, and an analysis of 20 additional cases is presented. The findings in this study are consistent with previous reports that the radiographic appearance may be indistinguishable from that of pathologic conditions; in some cases, the condition may be confused with aggressive tumors. It may also be significant that, in 16 of our 20 cases, the defects were found in regions where there had been previous extractions.

Adult↗
PubMed1987

Complications of endodontic therapy in florid osseous dysplasia.

A case in which endodontic therapy triggered an exaggerated inflammatory reaction in a patient with preexisting florid osseous dysplasia is presented. We suggest prophylactic antibiotic treatment before endodontic therapy in patients with this condition.

Adult↗
PubMed1985

Colonization of nonmelanocytic cutaneous lesions by dendritic melanocytic cells: a simulant of acral-lentiginous (palmar-plantar-subungual-mucosal) melanoma.

Four cases of colonization of nonmelanocytic lesions by dendritic melanocytic cells are reported, one in a verruca vulgaris of the lip, one in a squamous cell carcinoma in situ of mucous membrane overlying a tonsil, one in a lesion of lichen simplex chronicus with a nevocellular nevus of the external ear, and one in a dermatofibrosarcoma protuberans (Bednar tumor). This is an important biological process of melanocytes that must not be confused with the acral-lentiginous (palmar-plantar-subungual-mucosal (P-S-M) melanoma. It is probably much more common than the paucity of published reports would indicate.

Adult↗
PubMed1984

Intraoral melanoacanthoma.

A 39-year-old black woman noted a pigmented lesion on her right buccal mucosa of which she had been previously unaware. Physical examination revealed a 2.0 X 1.8-cm uniformly pigmented, macular to slightly plaque-like, symmetrically folded, indented lesion. Histologic examination revealed a hyperplastic mucous membrane containing numerous dendritic melanocytes at all levels. No pleomorphism or cytological atypia was recognized and no fibrosis was present in the corium. The case was diagnosed as "melanoacanthoma."

Adult↗
PubMed1984

Necrotizing sialometaplasia: frequency of histologic misdiagnosis.

Necrotizing sialometaplasia is said to mimic carcinoma, both clinically and histologically. A review of approximately 10,000 oral biopsy specimens revealed only three cases of necrotizing sialometaplasia, all of which had been misdiagnosed as other benign entities. While this suggests that necrotizing sialometaplasia represents only 0.03 percent of biopsied oral lesions, it does not deal with the frequency of cases of this condition which heal spontaneously without being biopsied.

Diagnosis, Differential↗
PubMed1984

Oral warty dyskeratoma.

Warty dyskeratoma of the oral mucosa is a rare cause of solitary mouth lesions. Of the thirteen reported patients, only three have been described in the dermatologic literature. We now present an additional patient, and review both the medical and the dental literature on warty dyskeratoma. Various factors possibly related to its cause are discussed, including cigarette smoking, a heretofore largely unappreciated possibility.

Female↗
PubMed1981

Ethnic and cultural determinants of the perceptions of female dental students.

A survey of women dental students enrolled in all American and Canadian dental schools during the 1977-78 academic year was conducted to determine their backgrounds, current status, motivation regarding dentistry as a career, perception of the dental school environment, preferences in dental education, and future plans. The data were analyzed on the basis of ethnic or racial derivation to delineate differences in the perceptions of female dental students of various ethnic groups. Recognizing the nature of such differences may prove beneficial to dental educators, who must determine the specific problems faced by female students of various ethnic groups.

Adult↗