Application of the research electronic data capture (REDCap) system in a low- and middle income country- experiences, lessons, and challenges

The challenges of reliably collecting, storing, organizing, and analyzing research data are critical in low- and middle-income countries (LMICs), particularly in Sub-Saharan Africa where several healthcare and biomedical research organizations have limited data infrastructure. The Research Electronic Data Capture (REDCap) System has been widely used by many institutions and hospitals in the USA for data collection, entry, and management and could help solve this problem. This study reports on the experiences, challenges, and lessons learned from establishing and applying REDCap for a large US-Nigeria research partnership that includes two sites in Nigeria, (the College of Medicine of the University of Lagos (CMUL) and Jos University Teaching Hospital (JUTH)) and Northwestern University (NU) in Chicago, Illinois in the United States. The largest challenges to this implementation were significant technical obstacles: the lack of REDCap-trained personnel, transient electrical power supply, and slow/intermittent internet connectivity. However, asynchronous communication and on-site hands-on collaboration between the Nigerian sites and NU led to the successful installation and configuration of REDCap to meet the needs of the Nigerian sites. An example of one lesson learned is the use of Virtual Private Network (VPN) as a solution to poor internet connectivity at one of the sites, and its adoption is underway at the other. Virtual Private Servers (VPS) or shared online hosting were also evaluated and offer alternative solutions. Installing and using REDCap in LMIC institutions for research data management is feasible; however, planning for trained personnel and addressing electrical and internet infrastructural requirements are essential to optimize its use. Building this fundamental research capacity within LMICs across Africa could substantially enhance the potential for more cross-institutional and cross-country collaboration in future research endeavors.

Higher order multiple births in Nigeria: Experiences, challenges and neonatal outcomes in a private health facility

OBJECTIVES

The aim of this study is to describe the experience and outcome of higher order multiple (HOM) births in a private tertiary health facility in Nigeria.

MATERIALS AND METHODS

This was a retrospective review of records of HOM over 3 years in a private tertiary health facility in Nigeria. Relevant data on HOM births were extracted from both the patients' case notes, admission registers and maternity ward and delivery records of the hospital using a predesigned pro forma. Data were analyzed using Statistical Package for Social Sciences Version 22.0.

RESULTS

The prevalence of HOM births was 0.72% of 1950 births over the 3 years study period; while for triplets, quadruplets, and quintuplets were 0.56%, 0.1% and 0.05%, respectively. The mean gestational age was 32 ± 3 weeks, and all except three sets of triplets were by Assisted Reproductive Technology (ART). Respiratory distress syndrome, neonatal jaundice, and neonatal sepsis accounted for more than 80% of the neonatal complications noted in HOM births. However, there was no significant difference between neonatal survival of HOM as compared to twin deliveries, P = 0.08.

CONCLUSION

HOM is becoming increasingly common in Nigeria. The strongest risk factor is ART, and neonatal complications are common reinforcing the need to streamline ART protocols in Nigeria.

Risk perception and correlates of alcohol use among out-of-school youth in motor parks in Lagos State, Nigeria

BACKGROUND AND AIM

The prevalence of alcohol use has increased globally. Out-of-school youth are a vulnerable group who might have missed opportunities for learning healthy behaviours in a formal school environment. The purpose of this study was to determine the risk perception, pattern of use, and correlates of alcohol use among out-of-school youth in Lagos, Nigeria.

METHODS

A cross-sectional study was conducted among 380 out-of-school youth in motor parks in Lagos State, Nigeria, using interviewer administered questionnaires.

RESULTS

The lifetime prevalence of alcohol use was 61.1%, while 55.5% were current drinkers. Beer (57.3%) was the most consumed type of alcohol, followed by distilled spirits (29.8%). Using the CAGE scoring system, more than half (57.8%) of the current drinkers had a drinking problem. Almost three quarters (70.1%) had experienced at least one episode of alcohol intoxication within the past month. A considerable number of current drinkers (63.5%) desired to reduce their alcohol intake or stop drinking, while 45.5% had made unsuccessful attempts to do so within the past year. Only 28.9% had received assistance to quit or reduce their drinking and of these less than half (39.3%) received assistance from a professional or healthcare worker. Males were more likely to be current drinkers and to have experienced episodes of alcohol intoxication. Parental and peer drinking were associated with alcohol use but not with intoxication.

CONCLUSIONS

It is important to design specific programmes to reduce alcohol use among out-of-school youth in these settings.

Analysis of Elastic Tissue in Histological Variants of Pleomorphic Salivary Adenoma seen at the Lagos University Teaching Hospital over a period of 35 Years

BACKGROUND

Pleomorphic salivary adenoma (PSA), is known for its morphologic diversity. While reports of elastic tissue in PSA have been documented, the distribution of this tissue in histological variants of the tumour has not been documented. Perhaps such features may influence biological behaviour of these variants.

OBJECTIVE

To classify PSA in our series into histological variants, and determine possible variation in elastic tissue distribution in them.

METHODS

Eighty eight histologically diagnosed cases of PSA in the oral biopsy archives of the department of Oral Biology and Pathology, Lagos University Teaching Hospital, were retrieved. New H&E sections were cut to reconfirm diagnosis and Verhoeff-Van Gieson's stained sections were cut for demonstration of elastic tissue. Seifert et al.'s (1976) histological classification was applied and elastic tissue presence was determined and quantified for each case. Parameters studied included; sex, age, site, histological subtypes and presence of elastic tissue. Statistical analysis was undertaken using the EPI-INFO version 3.4.

RESULTS

Male:female ratio was 1:1.3. Most cases (63.6%) occurred in the age group of 21-40 years. Generally, palate (42.0%) was the most commonly affected site, while 53.4% of cases were in the minor salivary glands. Seifert et al. classified subtype II lesions were the most frequently observed (39.7%) and elastic tissue was confirmed in 91.0% of cases. No association was noted between proportion of elastic tissue and histological variants.

CONCLUSION

Seifert et al subtype II was the most frequently observed and no association was observed between proportion of elastic tissue and the histological variant of PSA.

Melanin pigmented periradicular lesions of extracted teeth: a report of 3 cases and review of the literature

This article reports 3 cases of melanin pigmented lesions among 75 histologically diagnosed periradicular lesions of extracted teeth. Case 1 was a 25-year old male who presented with one week history of toothache involving a tender carious left mandibular second molar tooth (37), with periapical radiolucency and diagnosed clinically as acute apical periodontitis. The lesion was diagnosed histologically (using Haematoxylin and Eosin) as periapical granuloma, while histochemical examination (using Masson-Fontana technique) showed the presence of round/oval shaped melanin pigmented macrophages (melanophage) in the lesion. Case 2 was a 54-year old male with one week history of toothache associated with tender carious right maxillary first molar tooth (16) with periapical radiolucency. A clinical diagnosis of acute apical periodontitis was made, but histological and histochemical examination showed a melanin pigmented periapical granuloma with spindle shaped melanophage. Case 3 was a 28-year old female who presented with 4 days history of toothache, involving the tender left mandibular first molar tooth (36). The lesion had periapical radiolucency and a clinical diagnosis of acute apical periodontitis. On examination histologically and histochemically, the lesion was diagnosed as an intraosseous melanocytic naevi with dark-brown nests of round naevus cells. In conclusion, this article shows the rarity of melanin pigmented periradicular lesions in the jaws. The cases reported suggest that the trigger for formation of melanin-pigmented cells in the periradicular lesions may be related to the acute phase of the lesions. Further study is recommended to determine if the remnants of the migratory neural crest cells are the precursors of melanin-pigmented cells in the periradicular region.

Clinicopathological characteristics of odontogenic myxoma in Nigerians

BACKGROUND

Odontogenic myxoma (OM) is a locally aggressive neoplasm whose clinicopathological characteristics have not been extensively reported in Nigerians.

OBJECTIVE

To describe the clinicopathological characteristics of cases of OM seen at the Lagos University Teaching Hospital in Nigeria.

METHODS

A review of both clinical and histopathological records of sixty-three cases of OM diagnosed over a period of thirty-seven years was undertaken. The cases were analyzed for age, sex, site, size, duration and histological contents of collagenization, odontogenic epithelium and calcification.

RESULTS

Odontogenic myxoma represented 63(11.2%) cases of odontogenic tumours, was commonest in the second to forth decades and rare below age 10 and above 70 years. It was more common in females. Maxillary lesions were more common with respect to both central and peripheral histologic types, but occurred in equal frequencies in mandible and maxilla with respect to the central histologic type. Forty-seven (74.6%) cases were fibromyxoma and sixteen (25.4%) myxoma. Odontogenic epithelium was rare and observed in 5 (9.5%) cases while calcific material was present in sixteen (25.4%) cases. Late presentation was a common feature and surgical excision was the treatment of choice.

CONCLUSION

Odontogenic myxoma is un-common among Nigerians when compared with ameloblastoma. Clinicopathological characteristics in this series are similar to information in the scientific literature.

Clinicopathological study of 100 Nigerian cases of ameloblastoma

Clinicopathological analysis and growth rate study of 100 cases of ameloblastoma was undertaken. The tumour had site predilection for the mandible (91.0%) and occurred more in males than in females (ratio 1:0.9). 62.0% of patients in the series were less than 20 years of age. The estimated monthly growth rate (EMGR) of ameloblastoma was observed to be slower in males although the mean tumour volume recorded in females was lower than males in the series. The biologic aggression of 4 various types of ameloblastoma was predicted using EMGR and average volume of tumour at hospital presentation as predictive markers. Solid multicystic ameloblastoma was observed with the fastest EMGR of 0.81 cm(3)/month. Peripheral ameloblastoma was observed with the slowest EMGR of 0.17 cm(3)/ month. It was concluded that all the 4 types of ameloblastoma observed were clinically distinct and showed varying biologic aggression. The solid multicystic type with the highest growth rate (0.81 cm(3)/month) was considered the most aggressive while the peripheral type (growth rate = 0.17 cm(3)/month) was the least aggressive. It is therefore necessary to distinguish between the various clinical types of ameloblastoma before a clinician proceeds with definitive treatment.

Adenomatoid odontogenic tumour: a clinico-pathological analysis and melanin pigmentation study of 31 Nigerian cases

AIM

Clinicopathological analysis and melanin pigmentation occurrence in adenomatoid odontogenic tumour (AOT) diagnosed and managed at the Lagos University Teaching Hospital during a 29- year period.

METHODS

Records of 31 cases were reviewed and standard epidemiological data were obtained. Haematoxylin and eosin stained slides of the cases were retrieved and reevaluated for reconfirmation of diagnosis. Celloidinised paraffin sections of all cases were subjected to Fontana Masson stain and melanin bleach to assess presence of melanin pigment.

RESULTS

AOT is an uncommon type of odontogenic tumour that is commoner in younger age group (8-35 years) with site predilection for the anterior maxilla (64.5%). Occurrence of melanin pigment in AOT was very rare as there was positive melanin pigmentation in only one case in spite of the fact that the study was carried out in a predominantly Black population.

CONCLUSION

Pattern of occurrence of AOT observed in this Lagos series is similar to previous studies in the scientific literature. Melanin pigmentation is rarely demonstrated in AOT even in a predominantly Black population.

Ectodermal odontogenic tumours: analysis of 197 Nigerian cases

This article presents a clinico-pathologic analysis of 197 cases of ectodermal odontogenic tumours archived in the Lagos University Teaching Hospital, Lagos Nigeria over a 21-year period. They were categorized according to the WHO classification of odontogenic tumours. Of the 197 cases, 182 (92.3%) were benign while 15 (7.6%) were malignant. Central ameloblastoma, which accounted for 88.3% in this series, was the most common benign neoplasm demonstrating predilection for males (58.6%) and the mandible (83.3%). The mean age of occurrence (+/-SD) was 31.00 +/- 13.9 (range 9-82 years). Similarly ameloblastic carcinoma was the most prevalent malignant tumour (5.6%) with a predilection for females (63.6%) and the mandible (81.8%). The mean age of occurrence (+/-SD) was 30.1+/- 20.7 (range 16-85) years. Follicular ameloblastoma was found to be the commonest histologic subtype seen in Nigeria.

Evaluation of nucleolar organizer regions in tumours of the jaw bones

Nucleolar organizer regions [NORS] are loops of DNA that transcribe to ribosomal RNA. They can be visualized as intranuclear black dots by histochemical staining with a colloid silver solution. Silver stained nucleolar proteins (AgNORs) were counted in a variety of jaw bone tumours. In osteosarcomas, the number of AgNORs was also quantified before and after chemotherapy. Malignant bone tumour cells possessed more than five small AgNORs (5.54 +/- 0.44). Nuclei of benign jaw bone tumour cells had less than three (2. 97 +/-0.61). A significant difference in the number of AgNORs between osteosarcoma before chemotherapy (5.76 +/- 0.50) and after chemotherapy (3.89 +/- 1.65) was observed. (P < 0.05). The number ofAgNORs in recurrent osteosarcoma, recurrent ameloblastic carcinoma and recurrent chondrosarcoma was much higher than in their respective primary lesion but without statistical significant difference. The results of the present study indicate that the AGNOR count might help in determining malignancy, evaluating the effect of chemotherapy, and deciding the prognosis.

Nucleolar organizer regions in jaw tumours of cartilaginous origin

Nucleolar organizer regions [NORs] are loops of DNA that transcribe to ribosomal RNA. They can be visualized as intranuclear black dots by histochemical staining with a colloid silver solution. Silver-stained nucleolar proteins [AgNORs] were counted in cases comprising of primary chondrosarcomas of three histologic grades, in chondromyxoid fibroma and in controls comprising of normal bone and cartilage tissues of the jaw bones. The AgNOR counts increased step-wisely from normal bone tissue [1.11 0.4], chondromyxoid fibroma [2.66 0.78], grade I chondrosarcoma [3.94 0.34], grade II chondrosarcoma [4.32 0.52], and grade III chondrosarcoma [5.54 0.44]. There was a statistically significant difference in the mean AgNOR counts between grade 1 and grade III chondrosarcoma [p < 0.05]. The mean AgNOR counts for benign cartilaginous [chondromyxoid fibroma] tumour was significantly lower than the mean, AgNOR count for malignant cartilaginous tumours [chondrosarcomas] [p < 0.05]. The results in the present study indicate that silver colloid staining is a useful technique for evaluating the proliferative activity of chondrosarcoma and benign cartilaginous tumour such as chondromyxoid fibroma.

Panoramic radiographic study of mental foramen locations in Saudi Arabians

A panoramic radiographic study was carried out on 404 dentate Saudi Arabians, to locate positions of the mental foramen. Results show that 83.7% of the mental foramen locations occurred in the interdental space between the mandibular premolars and apical to the mandibular second premolar. 9.35% occurred posterior to the mandibular second premolar, and 6.95% occurred apical/anterior to the mandibular first premolar. In female Saudis, the most common location of the mental foramen was apical to the mandibular second premolar (45.9%), while the most common location in male Saudis was the interdental space between the mandibular premolars (45.5%). Asymmetry of the mental foramen location, which was observed in 15.6% of the cases, was observed more often in males (17.9%) than in females (12.3%).

Epithelial jaw cysts: analysis of 126 Nigerian cases

One hundred and twenty-six Nigerian cases of epithelial jaw cysts were retrieved from case notes and biopsy records of the Department of Oral and Maxillofacial Surgery and Department of Oral Pathology and Oral Biology of the Lagos University Teaching Hospital. The cases were analysed for age, sex, site and methods of management. Results show that developmental odontogenic cysts (57.14%) were more common than inflammatory odontogenic cysts (26.94%). Dentigerous cyst (22.22%) was the most common epithelial jaw cyst, followed by radicular cyst (21.43%). Developmental non-odontogenic cysts were more than twice as common in females as in males. Sixty-eight per cent of epithelial jaw cysts were treated by enucleation, 10% by marsupialisation, 13% by jaw resection and 9% by surgical excision.

Serum endometrial IgG antibodies and soluble CD23 concentrations in patients with endometriosis

OBJECTIVE

Serum endometrial antibodies have been found inconsistently in patients with endometriosis. Soluble CD23 is elevated in diseases associated with B cell activation. We evaluated serum levels of soluble CD23 and endometrial IgG antibodies in patients with endometriosis to determine whether there is B cell activation in this condition.

DESIGN

Fifty-seven patients with pelvic pain diagnosed as endometriosis and 40 patients without pelvic pain or endometriosis who had laparoscopic sterilisation were sequentially recruited into the study. Blood was collected and the sera assayed by ELISA for endometrial IgG antibodies and soluble CD23.

RESULTS

There was a significant difference between endometriosis and control group in both the serum IgG endometrial antibodies (p < 0.05) and soluble CD23 (p < 0.05). There was significant but weak correlation between endometrial antibodies and soluble CD23 (r = 0.3, p = 0.039), particularly in mild but not severe endometriosis.

CONCLUSIONS

These data suggest the existence of B cell activation in patients with endometriosis with a significant correlation between endometrial antibodies and soluble CD23. Mild endometriosis appears to be immunologically more active than the severe form. The value of soluble CD23 in the management of endometriosis needs further evaluation.

Odontogenic tumors: analysis of 289 Nigerian cases

Two hundred and eighty-nine cases of odontogenic tumors that accumulated in the files of the biopsy service of the Lagos University Teaching Hospital during a period of 21 years were analysed and categorised according to the most recent WHO classification of odontogenic tumors. Odontogenic tumors constituted 19% of all oral/jaw tumors and tumor-like lesions. Ameloblastoma, which accounted for 58.5% of odontogenic tumors in the series, was the most common, and showed a predilection for males and the posterior mandible. 94.8% of odontogenic tumors were benign, while malignant odontogenic tumors accounted for 5.2%. Odontogenic carcinoma was the most prevalent malignant odontogenic tumor; it showed a prediction for the mandible and occurred at a mean age of 37 years.

Orofacial granulomatosis: report of two Nigerian cases

Two cases of orofacial granulomatosis are reported. One case is that of a 24-year-old Nigerian female, who presented with a complete form of Melkersson-Rosenthal syndrome. The second case is that of a 32-year-old Nigerian male who presented with a form of orofacial granulomatosis which is consistent with Miescher's cheilitis granulomatosa, and who also gave a history of intolerance to some food items. The relevant literature is reviewed.

Clear-cell ameloblastoma of the mandible (a case report)

An ameloblastoma with histologic evidence of clear cells in a 15-year-old Nigerian male patient, who presented with a slow-growing, intraosseous, anterior mandibular swelling, is reported. The lesion was treated by surgery alone, and has not shown any recurrence 5 years after initial surgery.

Light microscopic, cytochemical and ultrastructural studies of a rat odontogenic epithelial cell line

An odontogenic epithelial cell line, ROE-2B, was established by propagating disaggregated immature, unmineralized maxillary third molar tooth germs from 11-day old Sprague-Dawley rats on a feeder layer of Mitomycin-C treated NIH 3T3 embryonic mouse fibroblasts. The cell line has been maintained for more than 6 months and through 7 passages. Light microscopic examination of cells revealed colonies with epithelial morphology. Electron microscopic examination confirmed the epithelial nature by the demonstration of tonofilaments, desmosomes and basal lamina. Cells were also shown to have secretory vacuoles, an abundance of granular endoplasmic reticulum, free ribosomes, Golgi complex and mitochondria. Surface activity in the form of pseudopodia-like projections and micropinocytosis were noted. Epithelial cells forming keratin were demonstrated by a positive histochemical reaction with Rhodanile Blue. Immunohistochemical studies showed a positive reaction for CAM 5.2 indicating that the ROE-2B cells express the cytokeratins of simple or glandular epithelia. The ROE-2B cell line will be useful for studies on in vitro biological behaviour of odontogenic epithelial cells, and may allow the establishment of in vitro models of odontogenic tumours.

Effect of oral contraceptive on early DMBA carcinogenesis of the rat palatal mucosa

Experiments were undertaken to find out whether administration of oral contraceptive (OC) per nasogastric tube could accelerate or inhibit early carcinogenesis of the rat palatal mucosa induced by painting 0.5% solution of 7,12-Dimethyl benz (a) anthracene (DMBA) in liquid paraffin. Forty female Sprague-Dawley rats were divided into 8 groups consisting of 5 animals per group. Group I--DMBA; Group II--DMBA + Oral Contraceptive I (13.0gm% Norethindrone + 8.7mg% ethyl estradiol); Group III--DMBA + Oral Contraceptive II (6.5mg% Norethindrone + 4.3% ethyl estradiol). Group IV--Oral Contraceptive I, Group V--Oral Contraceptive II, Group VI--liquid paraffin, Group VII--Corn oil and Group VIII--untreated control. Each animal was sacrificed at 18 weeks, the palatal mucosa degloved, fixed in 10% formal saline, sectioned in paraffin at 5u, stained with Hematoxylin and Eosin and evaluated histologically for features of epithelial dysplasia. Morphometric analysis was performed on epithelial and keratin thickness. Results indicate higher mean grade of epithelial dysplasia for group II when compared to group I (P less than 0.01) thereby suggesting a cocarcinogenic action for the Oral Contraceptive I. Lower dose Oral Contraceptive II was, however, unable to produce any significant mean grade of dysplasia in group III, suggesting further that the cocarcinogenic action of the Oral Contraceptive used was dose dependent. Morphometric analysis shows a decrease (P less than 0.01) in Keratin and palatal epithelium in DMBA treated animals and further decrease (P less than .001) in those two structures when Oral Contraceptive was used in combination with DMBA, suggesting that the cocarcinogenic action of Oral Contraceptive could result from the induced atrophy of keratin/epithelium and subsequent improved access of the DMBA to target cells in the basal layer of the epithelium. It is suggested that Oral Contraceptive accelerated the induction of early DMBA carcinogenesis of the rat palatal mucosa in this study.

Odontogenic carcinoma arising from ameloblastoma

A case of odontogenic carcinoma of the mandible is reported. Clinical and microscopic evaluations of the case are suggestive of a specific diagnosis of ameloblastic carcinoma. The case occurs at a lower age than previously reported for ameloblastic carcinoma. There has been no recurrence three years following treatment with a combination of surgery and radiotherapy.

Burkitt's lymphoma of the jaws in Lagos. Ten-year review

This paper presents a review of Burkitt's lymphoma of the jaws seen at the Lagos University Teaching Hospital. The debate on certain aspects of the disease, particularly the pathogenesis, has also been reviewed, while the experience gained in the management has been included.

Squamous cell carcinoma of the oral cavity. A clinico-pathological study of 106 Nigerian cases

A total of 106 patients with squamous cell carcinoma of the oral cavity and maxillary sinus in Nigerians were studied and analysed clinicopathologically for sex, age, site distribution as well as histological differentiation. The lesion was commoner in males than females (ratio 1.3 to 1.0) and was recorded in the age range 14 to 80 years. The mean age at presentation was 49 +/- 15.2 years, median age 49.5 years and a mode value at 51-60 years. The mandibular gingiva was the commonest anatomical site for the lesion, accounting for 28.6% of the total. Almost half of the cases (47.2%) presented histologically as well differentiated squamous cell carcinoma. Poorly differentiated squamous cell carcinoma was seen at a lower mean age 43 +/- 16 years when compared to other histological types.

Vitamin E stimulates proliferation of experimental oral carcinoma cells in vitro

Vitamin E was found to have a stimulatory effect on the growth in culture of an epidermoid carcinoma cell line derived from chemically induced tumors of hamster buccal pouch. This effect was found to be dose related, with a maximum stimulatory effect at 10 microM. At a concentration of 100 microM, there was an inhibitory effect on both cell turnover and colony formation.

A histologic study of epithelial dysplasia in oral lichen planus

One hundred cases of oral lichen planus were reviewed together with 100 nonspecific oral mucosal inflammatory lesions as a control group. The presence of dysplasia was noted, using well-established histologic criteria. Mild dysplasia was found in 57% of cases, moderate dysplasia in 9%, and severe dysplasia in 2% of cases. In the control group, mild dysplasia was observed in 32% of cases, moderate in 10%, and severe dysplasia was not present. It is suggested that, while mild or moderate dysplasia may not indicate precancerous potential, severe dysplasia in lichen planus may signify the development of a precancerous lesion.

Alpha tocopherol alters the distribution of Langerhans cells in DMBA-treated hamster cheek pouch epithelium

Thirty-seven adult male and female golden hamsters (Mesocricetus auratus) were divided into four experimental groups. In Group A, the animals served as untreated controls, having the left buccal pouches painted with mineral oil. In Group B, the animals received 10 mg vitamin E (alpha tocopherol) in peanut oil by the oral route, with a fine pipette, twice weekly. In Group C animals, the left buccal pouch was painted three times weekly with DMBA (0.5% solution of 7,12 dimethylbenz(a)anthracene in heavy mineral oil). Group D animals received both vitamin E and DMBA in the amounts indicated for Groups B and C, with the vitamin E being administered on days alternate to the DMBA painting, also in the manner described for the above groups. All animals were killed after eight weeks of treatment. Epithelial whole mounts were prepared from the left buccal pouches. These specimens were then stained for ATPase to demonstrate the presence of Langerhans cells (LCs). A notably decreased density of LCs was observed after treatment with DMBA. Vitamin E administration in addition to DMBA treatment resulted in a less dramatic decrease in LC density. Since vitamin E has been shown to retard experimental oral carcinogenesis, vitamin E may retard carcinogenesis by maintaining the number of Langerhans cells.

Retardation of experimental oral cancer by topical vitamin E

Forty-eight young male and female golden hamsters (Mesocricetus auratus) were divided into four groups of 12 animals each. The left buccal pouches of Group 1 and 2 animals were painted 3 times weekly with a 0.5% solution of 7,12-dimethylbenz(a)anthracene (DMBA) in heavy mineral oil for 7 weeks. At the end of this period, the left buccal pouches of Group 2 animals were painted 3 times weekly with vitamin E (DL-alpha-tocopherol, in pure form) for an additional 4 weeks. Group 3 animals were painted with vitamin E only, for 4 weeks. Group 4 animals were untreated controls. Group 2 animals demonstrated a significant delay in tumor formation in comparison with Group 1 animals. Gross observation revealed fewer and smaller tumors in the Group 2 animals; microscopic examination revealed smaller tumors with better cellular differentiation and less invasion. No tumors were observed in Group 3 and Group 4 animals. These observations were similar to those made in previous studies of oral carcinogenesis using systemic vitamin E to delay tumor formation.

Initiation and promotion in experimental oral carcinogenesis

A subthreshold dose of 0.1% DMBA in oil applied to hamster buccal pouch three times a week for 10 weeks did not result in the development of carcinoma in up to 25 weeks from the start of the experiment. However, if the subthreshold dose of DMBA was followed by 6 weeks of no treatment and six weeks of 40% benzoyl peroxide treatment, carcinomas developed rapidly. Both benzoyl peroxide and its acetone solvent are noncarcinogenic. An experiment carried out on sixty-six young adult male and female Syrian hamsters demonstrated these results, using appropriate controls.

An epidermoid carcinoma cell line derived from hamster 7,12-dimethylbenz[a]anthracene-induced buccal pouch tumors

w cell line, HCPC I, was established from an epidermoid carcinoma of the Syrian golden hamster cheek pouch. The carcinoma was induced by applications three times a week of a 0.5% solution of 7,12-dimethylbenz[a]anthracene (DMBA) in heavy mineral oil. The HCPC I cell line has been maintained through 60 passages over 15 months. Electron microscopy of the cell line revealed tonofilaments and desmosomes, thereby confirming its epithelial nature. Presence of keratin in the HCPC I cells was demonstrated by both histochemical and indirect immunofluorescence studies. The population-doubling time of HCPC I, estimated from the exponential growth phase of the growth curve established for the cell line, was 12 hours. The plating efficiency of the cell line was estimated at 35%. When an inoculum size of HCPC I, numbering 2.4 X 10(7) cells, was transplanted to the cheek pouch of an immunosuppressed inbred hamster, a papillary tumor, measuring 5 X 1 mm and microscopically diagnosed as a well-differentiated epidermoid carcinoma, developed 1 week post transplantation. Further successful transplantation was achieved with 1.8 X 10(7) HCPC I cells inoculated into the cheek pouch of a nonimmunosuppressed inbred hamster. A raised plaquelike mass, microscopically diagnosed as invasive epidermoid carcinoma, developed in the hamster cheek pouch 5 weeks post transplantation. Furthermore, 5 nonimmunosuppressed hamsters that received 1 X 10(6) HCPC I cells on their cheek pouches developed tumors microscopically diagnosed as anaplastic carcinomas 14 weeks post transplantation. The largest of these tumors measured 2 cm in diameter.

Oral mucosal tumor inhibition by ibuprofen

Eighty young adult male and female golden hamsters (Mesocricetus auratus) were divided into four equal groups. The left buccal pouches of the animals in group 1 were painted three times weekly for 24 weeks with 0.1% solution of 7,12-dimethylbenz[a]anthracene (DMBA) in heavy mineral oil. The left buccal pouches of the animals in group 2 were similarly painted with DMBA for 24 weeks, but the animals also received 10 mg ibuprofen (Motrin) administered systemically by the oral route twice weekly. The animals in group 3 received only ibuprofen, and those in group 4 served as untreated controls. After 24 weeks the animals were killed in groups of 16 (two males and two females from each of the four experimental groups) per week and their left buccal pouches studied for the presence of tumors. Sizes of tumors were also recorded. Ibuprofen was found to prevent tumor formation at 25-27 weeks. Some tumors developed in the animals receiving DMBA and ibuprofen by the 28-29 week, but they were fewer in number and smaller than those of the animals receiving only DMBA and not ibuprofen.

Two-phase carcinogenesis in hamster buccal pouch

A two-phase mechanism of chemical carcinogenesis in hamster buccal pouch has been demonstrated. Painting of buccal pouches three times weekly with a 0.1 percent solution of 7,12-dimethylbenz(a)anthracene (DMBA) in mineral oil for 10 weeks resulted in no visible tumors nor any microscopic evidence of dysplasia after the animals had been maintained for a 20 week period (Group 1 animals). Painting with 0.1 percent DMBA for 10 weeks, no treatment for a following 6 week period, and painting with 0.5 percent DMBA for a subsequent 4 weeks resulted in epidermoid carcinomas (Group 2 animals). Painting with 0.5 percent DMBA for 4 weeks in animals without prior treatment resulted in no tumors (Group 3 animals). It is postulated that the early treatment in Group 2 may serve for initiation and the later treatment for promotion.