Lysosomal-mediated degradation of apoptotic thymocytes within thymic nurse cells.

A thymic epithelial cell line (tsTNC-1) that maintains the ability to selectively bind and internalize immature alphabetaTCR(lo)CD4(+)CD8(+) thymocytes in vitro was used in long-term coincubation experiments to determine the ultimate fate of thymocytes that remained within intracytoplasmic vacuoles of thymic nurse cells (TNCs). In an earlier report, a subset of the population released from the TNC interaction was shown to mature to the alphabetaTCR(hi)CD69(hi) stage of development, while thymocytes that bided within the TNC cytoplasm died through the process of apoptosis. Here, we show the presence of both apoptotic and nonapoptotic thymocytes within the cytoplasm of freshly isolated TNCs as well as in tsTNC-1 cells in culture. A microscopic analysis revealed total degradation of the cytoplasmic apoptotic thymocyte population that remained in tsTNC-1 cells after an 8- to 10-h incubation period. A quantitative analysis showed an increase of cytoplasmic thymocyte degradation over time to almost 80% after 9 h of incubation. However, in the presence of bafilomycin A1, which is used to inhibit acidification of lysosomal vesicles, degradation of apoptotic thymocytes never reached 10%. These data suggest that lysosomes within TNCs play a role in the degradation of apoptotic thymocytes. We examined tsTNC-1 cells before the addition of thymocytes to cultures and found lysosomes to be clustered around the nucleus in the cytoplasm of TNCs. Shortly after the internalization event, apoptotic thymocytes move to the area of the cytoplasm containing lysosomes. Using the confocal microscope, we obtained evidence that shows the degradation event to be facilitated through the fusion of lysosomes with the specialized vacuoles within TNCs containing apoptotic cells.

Traumatised primary teeth in Nigerian children attending University Hospital: the consequences of delays in seeking treatment.

The objectives of this study were to investigate the occurrence, causes, types and severity of trauma to primary teeth in a hospital population, and to evaluate the interval between injury and treatment. The records of 1809 children treated in a two year period at the Ibadan University College Hospital were reviewed. There were 122 children aged one to seven years, with the highest frequency of trauma in the four and five year age groups, with no significant difference between boys and girls. Falls (88 per cent) were the commonest cause, and 57 children (47 per cent) had two injuries per episode of trauma. The majority (94 per cent) were luxation injuries and 6 per cent were fractures. Eighty-nine per cent of the injuries affected the maxilla, and the maxillary central incisors were the most frequently affected teeth, accounting for 68 per cent of all injuries. Only 11 per cent of the injuries presented for treatment on the day of trauma, while 10 per cent presented later than one year after trauma. The results suggest that the parents of these children with dental trauma do not bring the children for early treatment. The findings underscore a need to improve oral health awareness in general, but more importantly they emphasise that parents should obtain treatment for their children as soon as possible following any episode of dental trauma.

Preparation of feeding obturators for infants with cleft lip and palate.

Clefts of the lip and palate are the commonest congenital craniofacial malformations in children. Sucking is impaired in infants born with complete clefts of the lip and palate. Feeding obturators improve feeding thereby contributing to weight gain and a thriving state of health, a prerequisite for surgical repair of the defects. A pediatric dentist may be required to fabricate the obturator. A method for constructing the appliance is presented. The severity of the clefts varies so much that stock trays are not always useful for the impression of the infant's maxillary arch. A preliminary impression is taken by introducing a thermoplastic impression material with the index and middle fingers as the tray. A model is produced from which a custom tray is constructed. The final maxillary impression is taken using an irreversible hydrocolloid with the child in an upright position. An obturator is constructed on the stone model by sprinkling soft autopolymerizing acrylic resin on the palate extending well into the mucobuccal fold area. The cured appliance is trimmed and polished prior to insertion.

Cleft lip and palate as seen in the University College Hospital, Ibadan.

The purpose of this study was to update cleft lip and palate anormalies in Nigerian Africans using clinic materials. Hospital available information about records of 45 children with cleft lip and palate were reviewed. The 24 males and 21 females were all seen at the Dental centre, U. C. H., Ibadan during a period of six years. Twice more females than males had complete cleft of the palate and alveolar process on one side of the premaxilla. Majority of the clefts of the soft and hard palates on both sides of the premaxilla occurred in males with a male-to-female ration 6:1. There were several bilateral clefts and a preponderance of left unilateral clefts over clefts on right side. No other clear-cut patterns emerged probably because of small sample size.

Necrotizing ulcerative gingivitis and cancrum oris (noma) in Ibadan, Nigeria.

This study analyzed 58 cases of necrotizing ulcerative gingivitis (NUG) and 5 cases of cancrum oris among children who sought treatment at the Ibadan University College Hospital, Dental Centre in a 1-year period. The peak occurrence of NUG was among 4- and 5-year old children and 84.5% of them were in the 2 to 7 years age range. Seventy-two percent presented in the rainy season with positive history of recent febrile illness in 55 cases. There was no statistically significant association of NUG and rainy season. Possible predisposing factors in NUG and cancrum oris such as malnutrition, infectious childhood diseases, HIV infection, and immune compromise are discussed. It is suggested that children at risk should be advised to maintain good oral hygiene, adequate nutrition, and proper medical care.

Utilization of dental services by children at the University College Hospital, Ibadan, Nigeria.

This preliminary study examined the attendance and dental conditions of 1359 Nigerian children who sought care at the Ibadan University College Hospital in one year. There was an average of 113 new visits per month. Their monthly attendance showed a scholastic more than a seasonal pattern with the highest attendance during the end-of-session holiday. 59% of the children had caries and 17% had dental trauma. Only 10% had malocclusion, 5% enamel hypoplasia and 4% acute necrotizing ulcerative gingivitis. A majority of the children presented late for treatment.

Risk factors for dental fluorosis in a fluoridated community.

We conducted a case-control study to determine the sources of fluoride which are particular risk factors to dental fluorosis. Cases and non-cases were identified by the screening of 8-, 9-, and 10-year-old schoolchildren in the fluoridated community of East York, Ontario. Parents were interviewed about the child's first five years of residence and about diet and preventive caries practices. The Mantel-Haenszel odds ratio and associated chi-square tests were used to assess the association of fluorosis with several potential sources, controlling for other sources of fluoride and mother's education. The prevalence of mild fluorosis [1-4 on the Thylstrup and Fejerskov (1978) Index] was 13%. Those who brushed their teeth before the age of 25 months had 11 times the odds of fluorosis compared with those beginning toothbrushing later; prolonged use of infant formula (greater than or equal to 13 months) was associated with 3.5 times the risk of fluorosis, compared with no, or shorter duration of, formula use. We estimate that these factors were responsible for 72% and 22%, respectively, of the cases in our population. Dental fluorosis is not a public health problem in East York, but parents should be advised to supervise toothbrushing by children under 2 years of age.

'Acceptance of loss' and industrial rehabilitation: an empirical study.

414 disabled persons admitted into one Industrial Rehabilitation Unit over a period of 44 weeks were administered with Osuji's (1969; 1975) 'Acceptance of Loss'-Scale (ALS) during their first and fifth week at the center. The rehabilitees' performances at the center in terms of lateness, absenteeism, and employability rating by the final case conference panel were recorded. Two hypotheses were tested viz: that the ability to stick to a course of industrial rehabilitation (i.e. complete the course) and the ability to perform well at the course among those who complete the course will be a function of the level of acceptance of loss. The two hypotheses were upheld, indicating a high predictive validity of the ALS. The results are discussed in the light of the self-concept theory of Lecky, the cognitive balance and cognitive dissonance theories of Heider and Festinger respectively.