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Biomedical subjects

P Reichart

Publications and source records attributed to P Reichart.

At least 55 records · Page 3Linked to original sources
PubMed1987

Correlation between chewing and smoking habits and precancerous lesions in hill tribes of northern Thailand.

In a field study, 1866 people from different hill tribes (Lahu, Karen, Lisu and Meo) of northern Thailand and a group of rural Thai were examined for chewing, smoking and drinking habits and precancerous lesions of the oral mucosa. Traditional chewing and smoking habits were more prevalent among older people; cigarette smoking, in contrast, was more prevalent in younger and middle-aged individuals. Preleukoplakia was observed in 1.8%, leukoplakia in 1.1% and chewer's mucosa in 13.1% of the study population. Men and older patients were affected more frequently; chewer's mucosa was seen more often in women (Karen, Thai). A correlation between precancerous lesions and some oral habits could be demonstrated statistically.

Female↗
PubMed1986

The immunohistochemical distribution of collagens type IV, V, VI and of laminin in the human oral mucosa.

The distribution of collagens type V (form AB2) and VI was investigated on cryostat sections of normal human oral mucosa by indirect immunofluorescence. For comparison, antibodies to fragments of type IV collagen and laminin were also used to delineate basement membrane containing structures. All antibodies used were raised against human proteins. Type V collagen appeared as a microfibrillar structure throughout the interstitium, apparently touching but not being present within epithelial or vascular basement membranes. Microfibrils in blood vessel walls were limited to the intimal layer. Pericellular areas were not specifically stained. Type VI collagen appeared as an almost amorphous stromal structure becoming more prominent and more fibrillar in the upper connective tissue papillae. Intense staining was observed in the media of blood vessels and around smooth muscle cells. A possible role of type VI collagen in tissue stabilization may be expected from this ubiquitous and abundant distribution. The findings identify types V and VI collagen as important structures in the oral mucosa and serve as a basis for understanding morbid changes.

Antibody Specificity↗
PubMed1986

Cemento-fibrous dysplasia of the periodontal membrane (studies of the European hamster maxillary incisor).

The periodontal membrane of European hamster maxillary incisors showed histologic changes consisting of an irregularly orientated, less vascularized connective tissue which included abundant cementicle-like structures. The changes were multifocal and bilateral, growing towards the alveolar bone (Grade 1), causing atrophy of the alveolar bone due to compression (Grade 2) and reaching the periosteal membranes (Grade 3). In a few animals, the lesions were seen after one year. They were seen in 80% of hamsters more than 2 years old. Carcinogenic exposure did not alter the latency and incidence of the alterations. The lesions were thought to be a spontaneously occurring disease representing a nodular cemento-fibrous dysplasia of the periodontium. As, morphologically, no exact attribution to other odontogenic or mesenchymal growth could be made, the entity of this periodontal lesion was considered. Although the changes observed in the periodontal membrane of the maxillary incisors of the European hamster were not exactly comparable to odontogenic cemental lesions in man, they may serve as a model to further clarify the nature of fibro-osseous lesions.

Alveolar Process↗
PubMed1986

Immunohistochemical distribution of collagens types IV, V, and VI and of pro-collagens types I and III in human alveolar bone and dentine.

The aim of the present study was to characterize the composition of the organic matrix in alveolar jaw bone and dentine using antibodies against pro-collagens Types I and III and collagens Types IV, V, and VI. After demineralization of oral hard tissues in 0.2 N HCl, antigenicity was well preserved and the distribution of the pro-collagens and collagens could be demonstrated. Staining for pro-collagen Type I was prominent around osteoblasts and in pre-dentine, indicating active de novo synthesis of Type I pro-collagen. Pro-collagen Type I was ubiquitous but was less abundant in bone and dentine, whereas pro-collagen Type III was seen only in areas of bone remodeling, in peritubular spaces, and in pre-dentine. Type IV collagen was limited to the basement membranes of vessels in osteons and bone marrow. Type V collagen was detected neither in pre-dentine nor in bone. In contrast, Type VI collagen was found in dentine and bone, showing a faint but homogeneous staining which, similarly to pro-collagen Type III, was pronounced around osteoblasts and in pre-dentine, areas of active bone and dentine formation. This study showed that the organic matrix of dentine and bone contains Type VI as well as Type I collagen. Pro-collagen Type III (and to a lesser extent collagen Type VI) is transiently produced during new formation and remodeling of oral hard tissues, and disappears once the matrix calcifies. Type I pro-collagen qualifies as a general marker protein for increased osteoblastic activity. We conclude that immunostaining for the different collagen/pro-collagen types can be used to assess normal or abnormal stages of bone/dentine formation.

Adolescent↗
PubMed1985

Quantitative analysis of immunocompetent cells in human normal oral and uterine cervical mucosa, oral papillomas and leukoplakias.

Using monoclonal antibodies reacting with T-cell subpopulations, Langerhans cells and macrophages, the number and distribution of cells of the immune system in normal oral and cervical mucosa was determined and statistically compared with that in oral papillomas and oral leukoplakias. Increased numbers of labelled cells were found in oral leukoplakias and particularly in oral papillomas. In the epithelium of all specimens, Langerhans cells and T-lymphocytes of the suppressor/cytotoxic phenotype as well as of the helper phenotype were seen. Suppressor/cytotoxic and helper T-lymphocytes were in equal numbers in the epithelium of oral papillomas, but were about 2:1 in all other lesions. In normal oral epithelium, macrophages were rare but were in greater numbers in leukoplakias and papillomas. In the connective tissue of all lesions, more labelled cells were present than in epithelium with T-lymphocytes predominant. Although Langerhans cells were rare in connective tissue, many were seen in oral papillomas.

Antibodies, Monoclonal↗
PubMed1984

Occurrence of papillomavirus structural antigens in oral papillomas and leukoplakias.

Six oral papillomas and 7 oral leukoplakias were studied with genus-specific antibodies against detergent-disrupted papillomaviruses. Indirect immunofluorescence staining was applied to frozen sections. Distinct nuclear staining of superficial keratinocytes was seen in 5 of 6 oral papillomas, 2 of 5 homogenous leukoplakias, and in 2 cases of nodular leukoplakia, one of these showing transition into an invasive carcinoma. Papillomavirus antibodies offer a new way to detect and localize papillomaviruses in epithelial hyperplasias. The relevance of the immunomorphological identification of papillomavirus-associated antigens is discussed with special reference to the molecular hybridization technique.

Adult↗
PubMed1984

Ultrastructural findings in the oral mucosa of betel chewers.

Eighteen biopsies of the oral mucosa of northern Thai hilltribe betel chewers were studied histologically and by transmission and scanning electron microscopy (TEM, SEM). Clinically, varying stages of epithelial atrophy and one case of submucous fibrosis were observed. Histologically, epithelial atrophy with marked reduction of the rete pegs, hyperortho- and/or parakeratosis, and subepithelial edema and inflammatory changes were the prominent findings. On the ultrastructural level, cytoplasmic projections of the basal cells into the subepithelial stroma were seen. The basal membrane frequently revealed gaps; the interepithelial space was widened and unusual microvilli were observed on cell surfaces (SEM). Intercellularly, cristalloid material of unknown origin was also seen. The subepithelial connective tissue was characterized by dense bundles of collagen fibres adjacent to which masses of amorphous material were located. While some of the ultrastructural findings in the epithelium of betel chewers are indicative of early dysplastic changes, the nature of the juxta-epithelial stromal alterations is still unknown. Current hypotheses regarding the etiology of oral submucous fibrosis are briefly discussed.

Adult↗
PubMed1984

Morphologic study of jejunal mucosal transplants for the replacement of oral mucosa.

Biopsies were taken at 8 and 12 weeks and at 6 months from oral jejunal mucosal transplants in 5 patients who had undergone extensive surgery for tumors of the floor of the mouth. Microvascular anastomosed jejunal mucosa had been used for the primary reconstruction. Histological findings included flattening of the jejunal relief, atrophy and erosion of the epithelium with reduction of jejunal excretion and marginal overlapping of oral mucosa. Immunohistochemical labelling of the cytoskeleton revealed that jejunal epithelium does not undergo rapid metaplasia in the course of adaptation to oral mucosa. These findings indicate that the jejunal mucosa does not completely change its architecture and does not adapt to the requirements of the oral cavity after a period of 6 months.

Adult↗
PubMed1984

Streptococcus mutans and caries prevalence in Lisu and Karen of northern Thailand.

The prevalence of dental caries was studied in 139 Lisu and 167 Karen using the DMF-T index. Oral habits were recorded, including the chewing of betel nut. Samples of drinking water and betel constituents were collected and assayed for fluoride concentrations. Plaque material from 100 randomly selected individuals from each village was examined qualitatively for S. mutans. The DMF-T index scores for both tribal groups were low (0.00-1.00), and there was no significant difference in caries prevalence between betel chewers and non-chewers. Fluoride concentrations of the water samples were comparably low (0.02-0.29 ppm F). 30% of 200 plaque samples were positive for S. mutans, mostly of Biotype I.

Adolescent↗