Detection and typing of human papillomaviruses (HPV) in malignant, dysplastic, nondysplastic and normal oral epithelium by nested polymerase chain reaction, immunohistochemistry and transitional electron microscopy in patients of northern Greece.

OBJECTIVES: To evaluate the role of HPV in oral carcinogenesis, we examined the prevalence of HPV in malignant, potentially malignant and normal oral epithelium and studied the relation of HPV prevalence with other factors obtained from the patient's records. MATERIALS AND METHODS: Our material consisted of 291 tissue specimens from 258 individuals. From every individual formalin fixed and paraffin embedded tissues were examined by nested Polymerase Chain Reaction (NPCR) for the detection of HPV DNA and by immunohistochemistry (IHC) for the in situ detection of HPV L1 protein. Positive PCR products were sequenced in order to type HPVs. Also 33 fresh tissues were obtained, fixed and used to detect HPV particles by transitional electron microscopy (TEM). RESULTS: HPV was detected in 32.9% of the tissue specimens by NPCR, in 4.7% by immunohistochemistry and in 28.1% by TEM. In detail, by nested PCR HPV L1 DNA was detected in 40% of normal tissues, 40% of fibromas, 35.8% of non-dysplastic leukoplakias, 31.6% of dysplastic leukoplakias and 22.2% of oral squamous cell carcinomas. The HPV viral load of 96.5% of the samples was very low (1 viral copy per 10(2)-10(4) cells). HPV16 prevails in all histological groups in 89-100%. CONCLUSION: We conclude that HPV does not seem, from the specific sample examined, to play a substantial role in oral carcinogenesis. However, it cannot be excluded that HPV could be involved in oral carcinogenesis only in cases with high viral load or at early stages of carcinogenesis possibly through the hit-and-run mechanism.

Calcium folinate diminishes the teratogenic effects of all-trans retinoic acid in the developing craniofacial region and neural tube of the rat

This study tests the hypothesis that calcium folinate diminishes, or ameliorates, the teratogenic effects of all-trans retinoic acid during craniofacial and neural tube development. Four experimental groups were used; two were treated with three doses of 30mg/k.b.w all-trans retinoic acid (on gestational days 9, 10, and 11), with one of these groups having additional doses of calcium folinate (5mg/k.b.w.). The other two groups were given higher doses of all-trans retinoic acid (50mg/k.b.w), with again one of these groups having additional doses of calcium folinate (5mg/k.b.w.). Retinoic acid was administered by gastric intubation and calcium folinate by peritoneal injection. Two further control groups were used where the pregnant rats were exposed to neither all-trans retinoic acid nor calcium folinate. All rats were sacrificed on gestational day 18. Standard histological techniques were employed to assess the extent of abnormal development of the craniofacial region (including the palate) and the brain. The fetuses treated with all-trans retinoic acid alone showed varying degrees of neural tube defects (including excencephaly, myelomeningocele and spina bifida), eye malformations and clefting of the face and palate. However, fetuses treated with calcium folinate showed no neural tube and eye defects and only occasionally minor clefting in the presumptive hard palate. In addition, although many fetal absorptions and teratomas were seen within the litters of rats treated only with all-trans retinoic acid, there were no absorptions (and few teratomas) seen with calcium folinate supplements. The findings support our initial hypothesis concerning the beneficial effects of calcium folinate on craniofacial development (AU)

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All-trans-retinoic acid-induced disturbanceof forelimb digital apoptosis in mouseembryos: a preliminary scanning electronmicroscope (SEM) tudy

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Histological examination of major craniofacial abnormalities produced in rat foetuses with a variety of retinoids

Retinoic acid is a vitamin-A derived compoundthat plays an important role in craniofacialdevelopment. However, numerousstudies have shown that exogenously administeredretinoic acid analogues have teratogeniceffects both in humans and in experimentalanimals. This paper presents the results of astudy where exogenous administration ofretinoic acid analogues to pregnant Wistarrats resulted in major craniofacial malformationsof most of the foetuses. Seven groups ofpregnant rats were exposed to a variety ofretinoic acid analogues, administered in differentdoses on different gestational days. Afurther control group was not exposed to thesecompounds. All the rats were impregnatedand sacrificed on the same gestational days(GD 0 and GD 18 respectively). Followingexamination of the 34 foetuses obtained fromthe retinoic acid-treated litters, 5 were chosenfor histological investigation to describe themajor, external craniofacial malformationsresulting from exposure to the teratogens.These malformations included exophthalmos,anophthalmos, exencephaly, craniofacial asymmetryand facial tags. Also reported here arethe incidences of teratomas and absorptions inthese litters. Previously, we have reported theincidence of cleft lip and palate in rats subjectedto an identical experimental regimen. Ourdata provide further evidence that retinoicacid analogues, all-trans-retinoic acid in particular,disturb normal craniofacial developmentin such a way that a spectrum ofcraniofacial malformations can be induced byembryonic exposure to these compounds (AU)

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Palatal abnormalities in the developing rat induced by retinoic acid

Palatogenesis is a complex developmental processthat requires two main events: elevation andthen fusion of the palatal shelves. These processesare disrupted by teratogens such as retinoicacid (RA) and genetic defects, resulting in variousmalformations (including cleft palate). Usinghistological and immunohistochemical techniques,the effects of different isomers of RA, administeredin various concentrations to pregnantrats on different gestational days (GD), were assessedfrom observations of the state of palataldevelopment on GD 18 in foetuses without exencephaly.Varying degrees of clefting of thepalate were observed, from failure of elevationof the palatal shelves to failure of fusion in themidline. This study shows that all-trans-RA isthe most teratogenic RA isomer in terms of ratpalatal abnormalities. It also supports previousfindings that the timing of administration of alltrans-RA is more critical than the concentration,with treatment between GD 10 and 10.5 havingthe most severe effects. Previous histologicalstudies also suggested that RA is associatedwith the appearance of ectopic cartilages withinthe developing palate of foetuses showing exencephaly.In this investigation, immunohistochemicallabelling of the foetal material with antibodiesthat recognise epitopes present in linkproteins 1, 2, and 3 (8A4), chondroitin-4-sulphatestubs (2B6), and G1 and chondroitin sulphateattachments (7D1) present in aggrecan (associatedwith hyaluronan in cartilage) showedno signs of ectopic cartilage formation within the palate at GD18. Internal controls of the cartilagesof the nasal septum, vomeronasal cartilage, andMerkel’s cartilage labelled intensely and appearedmorphologically normal (AU)

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