Association of sotalol versus atenolol therapy with survival in dogs with severe subaortic stenosis

INTRODUCTION/OBJECTIVES

Dogs with severe subaortic stenosis (SAS) are at risk of dying suddenly from fatal arrhythmias. Survival is not improved when treated with pure beta-adrenergic receptor (β)-blockers; however, the effect of other antiarrhythmic drugs on survival is unknown. Sotalol is both a β-blocker and a class III antiarrhythmic drug; the combination of these differing mechanisms may provide benefit to dogs with severe SAS. The primary objective of this study was to compare survival in dogs with severe SAS that were treated with either sotalol or atenolol. The secondary objective was to evaluate the effect of pressure gradient (PG), age, breed, and aortic regurgitation on survival.

ANIMALS

Forty-three client-owned dogs.

MATERIALS AND METHODS

Retrospective cohort study. Medical records of dogs diagnosed with severe SAS (PG ≥ 80 mmHg) between 2003 and 2020 were reviewed.

RESULTS

No statistical difference was identified in survival time between dogs treated with sotalol (n = 14) and those treated with atenolol (n = 29) when evaluating all-cause mortality (p=0.172) or cardiac-related mortality (p=0.157). Of the dogs that died suddenly, survival time was significantly shorter in dogs treated with sotalol compared to those treated with atenolol (p=0.046). Multivariable analysis showed that PG (p=0.002) and treatment with sotalol (p=0.050) negatively influenced survival in the dogs that died suddenly.

CONCLUSIONS

Sotalol did not have a significant effect on survival overall but may increase the risk of sudden death in dogs with severe SAS compared to atenolol.

Age standardized incidence rates of oral cancer in South Africa, 1988-1991

While numbers of papers on oral cancer in South Africa have been published, there have been very few studies on standardized morbidity rates. This paper has developed data collected by the National Cancer Registry from the entire country for the four year period 1988-1991 to present frequency, age standardized incidence rates (ASIRs) and life-time risk (LR) for histologically-diagnosed intra-oral cancers in female and male Asian, black, coloured and white South Africans. During this period 5396 cases of oral cancer were diagnosed in a total number of 157,307 cancer cases (3.4 per cent) excluding squamous cell carcinoma (SCC) and basal cell carcinoma (BSC) of the skin. Intra-oral cancer in all South African females and males accounted, respectively, for 1.8 per cent and 5.0 per cent of all cancers. There was a male preponderance in black, coloured and white groups but females were affected more frequently than men among Asians. The incidence in Asian women (6.66) was higher than those of the women in any of the other population groups, whereas the lowest incidence was found in black women (1.75). The incidence rate in coloured men was particularly high (13.13) whereas the incidence in white males (8.06) was not substantially lower than among black males (9.05). Differences between the eight groups were not significant (X2 = 6.24, df = 3, p > 0.1). The Cumulative Life Time Risk (LR) of developing intra-oral cancer for males and females in the four population groups ranged from 1:65 in coloured males to 1:455 for black females. Gender differences in LR in both black and coloured groups, signals substantial differences in exposure to known carcinogens for this disease. It is disturbing to note that the incidence in the period 1988-1991 was higher in Indian women that it was in 1964-1966, and that educative preventive measures have failed. Similarly, the incidence of intra-oral cancer in coloured men of 13.13 is substantially higher than the figure of 8.8 reported in 1979. If this is an accurately reflected trend, then a major educative programme needs to be pursued in this direction if the relative risk of one in 65 is to be reduced.

Vacuolated cells and mucous metaplasia in the epithelial linings of radicular and residual cysts

The purpose of this study was to determine whether a consistent association exists between mucous cells and clear or vacuolated cells in the epithelial lining of radicular and residual cysts and to consider whether the vacuolated cells may represent a stage in the histogenesis of mucous metaplasia in these linings. Single sections from each of 154 mandibular radicular and residual cysts were stained with periodic acid-Schiff (PAS) after diastase digestion. Fifteen cases which showed mucous metaplasia were included in the study and were examined for the presence of vacuolated cells associated with the mucous cells. Mucous cells were present singly or in groups within all layers of the stratified squamous epithelial lining except the basal cell layer. In nearly all instances small to large ovoid vacuolated cells were found closely associated with the mucous cells. Occasional vacuolated cells contained sparse mucin granules or a delicate network of PAS-positive, diastase-resistant material. It is suggested that the clear cells may represent a stage in the histogenesis of mucous metaplasia.

Developmental odontogenic cysts. An update

This review paper reports recent advances in the subject of developmental odontogenic cysts, essentially those of the past decade, starting with reference to the new WHO classification (1). On keratocysts, the latest reported recurrence rates are assessed as are their mode of growth, immunocytochemistry, immunology, genetic studies, and work on specific keratocyst antigens. There is a critical account of the group of lesions which includes the gingival cyst of adults, lateral periodontal cyst, botryoid odontogenic cyst and glandular odontogenic cyst, and their possible relationship to one another. On dentigerous cysts, reference is made to the relationship between them and deciduous teeth, as well as to their immunocytochemistry and immunology. Recent work on the unicystic ameloblastomas, their classification and prognosis, is assessed, as is the calcifying odontogenic cyst and its relationship with solid odontogenic tumours.

Epidemiology of diarrhoeal illness associated with coccidian-like organism among travellers and foreign residents in Nepal

A newly described organism called CLB (coccidian-like or cyanobacterium-like body) has been identified in cases of prolonged diarrhoea. To confirm an association of CLB with disease and identify risk factors for transmission, we conducted a case-control study of travellers and foreign residents at two outpatient clinics in Kathmandu, Nepal. Patients without diarrhoea were matched to CLB cases by clinic and date of visit. For comparison, patients with other causes of diarrhoea were also studied. Stools were examined for enteric pathogens with standard microbiological and molecular genetic techniques. CLB was identified in 108 (11%) of 964 individuals with gastrointestinal symptoms compared with only 1 (1%) of 96 symptom-free controls (p = 0.003). 7% of residents in the US Embassy community acquired the infection. The diarrhoeal illness associated with CLB lasted a median of 7 weeks (interquartile range 4-9) compared with 9 days (4-19) for individuals with other causes of diarrhoea (p < 0.0001). The prevalence of other enteric pathogens was no higher among CLB cases than among symptom-free controls. Patients with CLB infection were more likely than controls to report consumption of untreated water (odds ratio 3.98; 95% CI 1.29-13.14); organisms of the same appearance were identified in an epidemiologically implicated water sample. The significant association of CLB with prolonged diarrhoea, and the low rate of other enteropathogens in CLB cases, strongly supports the hypothesis that CLB is a new pathogen. Epidemiological and environmental data suggest that the organism is waterborne.

The WHO Histological Typing of Odontogenic Tumours. A commentary on the Second Edition

This article introduces the revised World Health Organization (WHO) classification of odontogenic tumors and jaw cysts and certain bone lesions that either are peculiar to the jaws or have distinctive features in that location. The new and revised classification is compared with the previous version, the reasons for the changes are outlined, and reference is made to a number of newly characterized lesions that have been included.

Gingival cyst in adults

A retrospective study is reported of 14 cases of gingival cyst of adults. Clinical data were pooled with well-documented cases in the literature. Most cases occurred in the 5th and 6th decades and in the premolar-canine-incisor area. Microscopically, the epithelial lining ranged from a thin, flat to cuboidal layer, 1-3 cells thick, resembling reduced enamel epithelium, to a nonkeratinized stratified squamous epithelium without rete ridges, of about 5-6 layers. Epithelial cells were frequently atrophic and this could involve the full thickness of the epithelium leaving an amorphous band of eosinophilic material. Plaque-like epithelial thickenings are sometimes present. Multicystic or "botryoid" forms may occur. The cysts are of developmental origin, arising either from basal cell extensions of overlying epithelium; or from postfunctional odontogenic epithelial residues of the dental lamina or rests of Malassez; or from junctional epithelium in the gingival crevice. The latter theory of origin is favored.

The lateral periodontal cyst: an update

Lateral periodontal cysts account for 0.8% of all jaw cysts seen in our department. Published reports have indicated that they occur most frequently in the 5th to 7th decades, that there is a male preponderance and that they are located mainly in the mandibular canine-premolar region. In our own series of 20 cases, 10 were found in the anterior maxilla. We have distinguished unicystic and multicystic (including botryoid) varieties. They were lined predominantly or exclusively by thin reduced enamel epithelium-like tissue which contained many clear cells and epithelial thickenings referred to as plaques. Glycogen was present in the epithelium of two-thirds of our cases although not exclusively in the clear cells, many of which showed no positivity. Two of our examples of the botryoid variety were different histologically, being lined predominantly by non-keratinizing stratified squamous epithelium with crowded and pyknotic nuclei and no clear cells. One case contained melanin while another showed epithelial crypt formation and superficial palisaded low columnar cells as seen in the glandular odontogenic cyst. This raised the question of whether the latter may form part of the clinicopathologic spectrum of lateral periodontal cyst. The histogenesis of lateral periodontal cysts is uncertain but we favour origin from reduced enamel epithelium.

The unicystic ameloblastoma: a clinicopathological study of 57 cases

A clinicopathological study of 57 unicystic ameloblastomas has been undertaken, which represents 15% of all cases of ameloblastoma accessioned in our department over a 30-yr period. Of the cases where gender was recorded: 30 were male and 23 female. The majority of patients were black (51 cases) and most occurred in the mandible (52). This distribution conforms to that of solid and multicystic ameloblastomas. The mean age at diagnosis was 23.8 years (S.D. 14.9) which is significantly younger than for the conventional counterpart (p less than 0.1%). The lesions were classified histologically into 3 groups: Group 1 (42%) cyst lined by a variable often non-descript epithelium; Group 2 (9%) cyst showing intraluminal plexiform proliferation of epithelium; Group 3 (49%) cyst with invasion of epithelium into the cyst wall in either follicular or plexiform patterns. While Group 1 and 2 lesions may be treated by enucleation, Group 3 lesions should be treated aggressively as for conventional ameloblastomas. The objectives of correct histological diagnosis, subclassification and appropriate therapy are best achieved by enucleation biopsy. There is little evidence to support origin from pre-existing odontogenic cysts.

Epithelial dysplasia immediately adjacent to oral squamous cell carcinomas

A number of workers have attempted to identify dysplastic features which may be predictors of malignant change, by prospective studies of dysplastic lesions. In the present study we have looked at dysplastic changes immediately adjacent to established squamous carcinomas in an attempt to determine whether any predictors can be identified in this way. Eighty cases were included in the study for whom information on tobacco usage was known. Clinical details were recorded. Histological features in epithelium immediately adjacent to the carcinoma were studied in representative sections. Eighteen specific histological characteristics were noted as present or absent. Data were transferred by Conversational Monitoring System (CMS) terminal, processed and analyzed by the Statistical Analysis System (SAS) Computer package. Only 8 patients were non-smokers (10%). Dysplastic changes in adjacent epithelium were frequently multicentric. Changes appear to occur first in the basal layer in the form of disturbance of polarity or basal cell hyperplasia, while other dysplastic features are absent. The feature referred to as basal cell hyperplasia appears, in fact, to represent disturbed epithelial maturation. In 80% of cases increased nucleo-cytoplasmic ratio appears to result from a decrease in cytoplasmic volume rather than increased nuclear size. A defect in RNA synthesis may be a factor. A sharp decrease in inflammatory cells in the lamina propria of adjacent epithelium, compared with that of the carcinoma, was observed. Russell bodies were noted in 5 of the 8 lesions in non-smokers (63%) and in 16 of 72 lesions in smokers (22%) (p less than 0.001; Chi2 17.65).

A critical evaluation of epithelial dysplasia in oral mucosal lesions using the Smith-Pindborg method of standardization

Standardization is one of the greatest problems in assessing epithelial dysplasia, as is establishing the relative importance of different clinical and dysplastic features. In this study, 214 cases characterized histologically by varying degrees of epithelial dysplasia, were analyzed for various clinical features: and representative sections were assessed histologically and graded according to the Smith-Pindborg standardized scoring system. Data were analyzed by computer. Seven cases with scores of less than 10 were excluded as not dysplastic. There were 85 cases (41%) with scores of 11-25 which were regarded as mild dysplasia; 60 (29%) with scores of 26-45 were regarded as moderate dysplasia; and 62 (30%) with scores of more than 45 which were reported as severe dysplasia. Peak frequency was in the 6th decade and the severe dysplasias were most frequent in the 8th decade. The M:F was 2:1. Tongue (58 cases), lower lip (36), floor of mouth (32) and cheeks (26) were sites most commonly involved. Of 107 cases, 93 were described as homogeneous leukoplakia, 11 as speckled leukoplakia and 3 as erythroplakia. The distribution of mild, moderate and severe dysplasias did not differ significantly by age, sex or race. Half of all cases involving floor of mouth and oropharynx were severely dysplastic, whereas most lesions occurring in cheek and alveolar mucosa/gingiva were mildly dysplastic; but differences were not significantly different. Severe grades of each dysplastic feature, as might be expected, occurred in lesions classified finally as 'severe dysplasia'.(ABSTRACT TRUNCATED AT 250 WORDS)

Radicular cysts arising from deciduous teeth. Review of the literature and report of 23 cases

Radicular cysts arising from deciduous teeth are rare. 28 such cases have been recorded in the literature since 1898. In this study, we present 23 personally-observed cases of radicular cysts arising from deciduous teeth. The patients' ages ranged from 4 to 12 years with one exceptional case aged 19 years. The M:F ratio was 1.6:1. The mandible was affected more frequently than the maxilla and the deciduous molars were the teeth most commonly involved. 2 of the cysts presented multi-locular radiolucency; in 9 cases, buccal expansion was noticed and in 8 cases, permanent buds were displaced. Caries was the most common etiologic factor in the formation of the cysts. Histologically, cysts in varying stages of development were lined by proliferating non-keratinized stratified squamous epithelium.

Fibrous histiocytomas of the oral and maxillofacial regions

Fibrous histiocytomas of the oral and maxillofacial regions are rare. The present study analyzes a sample of 63 cases from the literature together with 7 personally observed cases. Age, sex, site, size, clinical behaviour, treatment and survival were evaluated and related to a histological classification based on that of Rosai (1981). Lesions were assessed for histological criteria which would place them in one of 2 groups: fibrous histiocytoma (FH) or pleomorphic fibrous histiocytoma (PFH). Within these 2 histological groups the cases were subdivided into clinically benign, aggressive or malignant lesions. Thirty-nine cases (56.0%) were classified as FH and 31 cases (44.0%) as PFH. The mean age of male patients with PFH was significantly higher than female patients with FH (t = 3.05; d.f. 37; p less than 0.0025). Lesions in the PFH group involved bone more frequently than those in the FH group (Yate's Chi2 = 16.66; d.f. 1; p less than 0.00025). Lesions involving bone for both histological groups were more likely to be aggressive or malignant than soft-tissue lesions (Yate's Chi2 = 29.9; d.f. 1; p less than 0.00025). Soft-tissue lesions were usually less than 5 cm in greatest diameter. Radiographic features of malignancy for lesions with bone involvement is of prognostic importance regardless of the histological appearance of the lesion. The majority of the lesions under study were from the deep tissues of the oral and maxillofacial regions.

Aneurysmal bone cyst of the jaws. (II). Pathogenesis

The pathogenesis of the aneurysmal bone cyst is the subject of much controversy. This study was undertaken to test the hypothesis that the aneurysmal bone cyst is a secondary phenomenon which occurs in a primary lesion of bone. Histological material from 303 bone lesions was studied for evidence of development of aneurysmal bone cyst. Microcysts and blood-filled spaces, similar to those seen in aneurysmal bone cysts, were observed in 15 of 54 central giant cell granulomas studied (28%). The frequency was lower (10%) in 49 cases of fibrous dysplasia and very low in ossifying and cementifying fibromas. 1 of 7 cases of Paget's disease of bone showed large blood spaces. It is postulated that the initiating process of the aneurysmal bone cyst is the microcyst, which forms as a result of intercellular oedema in a primary lesion with loose, unsupported stroma. Rupture of vessels into the microcysts introduces blood under haemodynamic pressure. With little resistance provided by the stroma, the blood spaces resorb the surrounding bone and lift the periosteum, which produces a thin shell of new bone. Similar histological features were observed in 6 of 42 fibrosarcomas examined (14%) and in 8 of a series of 75 osteosarcomas (11%). While many of these lesions did not present with clinical similarity to the aneurysmal bone cyst, it is postulated that this type of case may account for the so-called malignant aneurysmal bone cyst occasionally reported.

Aneurysmal bone cyst of the jaws. (I). Clinicopathological features

A clinicopathological study has been performed on a series of 42 well-documented examples of aneurysmal bone cyst of the jaws recorded in the literature, and 4 additional personally observed cases. Most occurred in the first three decades (93%), 2/3 of patients being younger than 20 years. There was a preponderance of females (62%). Both mandible and maxilla were involved, particularly the molar regions. A number of mandibular cases extended to the angle and ascending ramus. Swelling was usually present and there was frequently a history of rapid growth. Radiologically, they often appeared as multilocular radiolucencies with expansion and thinning of the cortical plates. Histologically, the lesions consisted of multiple cystic spaces of varying size, usually filled with blood. The intervening solid tissue frequently showed features of other pathological lesions, particularly the central giant cell granuloma, but occasionally as fibrous dysplasia, ossifying fibroma and cementifying fibroma. Recurrences have been common probably because of technical difficulties in entirely removing very large lesions. Thorough curettage, if necessary by an extraoral approach, is the most favoured method of treatment.

Intraoral salivary gland tumors: a retrospective study of 201 cases

Two hundred and one cases of intraoral salivary gland tumors were studied from the files of the School of Pathology, University of the Witwaterstrand and South African Institute for Medical Research. 145 cases (72.5%) were classified as benign, comprising 140 pleomorphic adenomas and 5 monomorphic adenomas. The other 56 cases were classified as malignant or potentially malignant tumors, represented by 21 adenoid cystic carcinomas, 15 adenocarcinomas, 13 mucoepidermoid tumors, 5 carcinoma in pleomorphic adenomas and 2 epidermoid carcinomas. The patients in the malignant/potentially malignant group were significantly older than those in the benign group and a smaller proportion of their tumors were palatal, the difference being statistically significant. The high frequency of pleomorphic adenoma might result from a relatively higher number of black than white patients in this sample.

Content and distribution of glycogen in oral epithelial dysplasia

Forty-four oral lesions with epithelial dysplasia and 25 other benign and malignant lesions of the oral mucosa were examined after staining with hematoxylin-eosin and diastase controlled PAS. The intensity of the PAS-positivity for glycogen, the grade of dysplasia, the type of keratinization and the degree of subepithelial inflammation were recorded. Histologically normal epithelium at the margins of the lesions were used as controls. The presence and amount of glycogen in normal epithelium at the margins of the lesions were used as controls. The presence and amount of glycogen in normal epithelium at the margin of the lesions were used as controls. The presence and amount of glycogen in normal epithelium varied with the form of keratinization in that non- or parakeratinized epithelium was rich in glycogen whereas there was a negative glycogen-reaction in orthokeratinized epithelium. The most striking feature was an abrupt limitation of the glycogen at the junction between nondysplastic and dysplastic epithelium. The difference in the amount of glycogen in normal and dysplastic epithelium as assessed semiquantitatively, was statistically significant. There was no statistically significant difference in glycogen content with different degrees of dysplasia. The diastase controlled PAS-staining may therefore be a useful method of distinguishing dysplastic from nondysplastic epithelium in doubtful cases. Pseudoepitheliomatous hyperplastic epithelium covering granular cell myoblastoma did not contain any glycogen. Five of six squamous cell carcinomas and four verrucous carcinomas contained no demonstrable glycogen. Glycogen was present in the epithelium of the cases of lichen planus and "denture hyperplasia" investigated.

Leukoplakia-like lesions developing in patients with oral discoid lupus erythematosus

In a long-term follow-up of 52 patients with oral lesions of discoid lupus erythematosus (DLE) 8 patients showed a gradual transition of the typical DLE lesions to lesions which closely resemble leukoplakia. Histopathologically and immunopathologically the leukoplakia-like lesions generally showed features similar to those in leukoplakias not preceded by DLE. Ultrastructurally, the leukoplakia-like lesions showed the presence of cytoplasmic tubular structures in vascular endothelium in two out of three patients examined. The leukoplakia-like stage is considered to be an inactive or scar-like stage, which may be the mucous membrane counterpart of the atrophic scars following DLE lesions of the skin. A primary examination of a DLE patient presenting oral lesions at the leukoplakia-like stage may result in an incorrect diagnosis. Therefore, when investigating patients with leukoplakias, they should be questioned on previous or present skin lesions as well as symptoms of systemic lupus erythematosus.

Dimensions of incisive fossae on dry skulls and radiographs

The dimensions of the incisive fossae of 960 Negroid skulls were measured and the frequency of nasopalatine duct cysts in this material was determined. A random sample of 200 of the above skulls was radiographed under standardized conditions and the radiographic dimensions of the incisive fossae were compared statistically with their actual dimensions. Incisive fossa widths of greater than 6 mm were found in 148 specimens (15.3%), and anteroposterior dimensions of greater than 7 mm were found in 799 specimens (82.4%). Thirteen cysts were found. Radiographic measurements of incisive fossae were significantly different from those made on the skulls. Mean dimensions of the fossae in this sample were greater than those previously reported and there was a higher frequency of nasopalatine duct cysts.

Verrucous hyperplasia of the oral mucosa

Verrucous hyperplasia of the oral mucosa is a relatively unrecognized entity that may resemble verrucous carcinoma clinically and histologically. This study describes the clinical and histological features of the condition, particularly in relation to verrucous carcinoma. Sixty-eight cases were selected by screening all lesions accessioned as verrucous or papillary lesions of various kinds, dysplasias and leukoplakias. More cases occurred in women (56%) than in men (44%). All but 3 patients were 50 yr. or older, and 35% were over 70. Gingiva or alveolar mucosa were involved most frequently (27%), followed by cheek (24%), tongue (17%), floor of mouth and lip (12% each), and palate (8%). Verrucous processes are either sharp and heavily keratinized or blunt with a thin parakeratin layer. In 36 patients (53%), there was associated leukoplakia; in 20 (29%), there was associated verrucous carcinoma; in 45 (66%), associated epithelial dysplasia; and in 7, (10%) there was associated squamous carcinoma. Verrucous carcinoma or squamous carcinoma. Verrucous hyperplasia is best distinguished from verrucous carcinoma in biopsies taken at the margins of the lesions. In the former, the verrucous processes and the greater part of the hyperplastic epithelium are superficial to adjacent normal epithelium. In the latter, the verrucous processes are superficial, but the broad rete processes extend considerably deeper than adjacent normal epithelium, often pulling a margin of normal epithelium down with them into the underlying connective tissue.

Basal cell extensions in human oral mucosa

Basal cell extensions have frequently been observed in a variety of odontogenic lesions as well as in the fibrous epulis (fibrous hyperplasia of the gingiva). In order to determine the frequency of these extensions in normal human oral nucosa, a study using autopsy and surgical material was conducted. The results indicated that a specific type of rete ridge morphology exists for gingiva, including the presence of thin double stranded extensions which may be related to the functional role of the gingiva or to the fact that the odontogenic apparatus is derived from surface epithelium in this region in the developing embryo, or both. Similar extensions have not been found in other oral epithelia.

Microscopic changes in rat tongue following experimental cryosurgery

Histological changes were studied in the rat tongue for varying periods of time up to 14 days following the application of a cryoprobe to the dorsal surface of rat tongue. Within minutes of the application, focal subepithelial vesiculation and hyperemia occurred. At 3 h there was evidence of damage to capillary walls, resulting in hemorrhage. Arterioles and venules were thrombosed and there were degenerative changes in the muscle layer of their walls. At 6 h ventral epithelium showed evidence of damage. At this stage vessel walls were pavemented with neutrophilic polymorphonuclear leukocytes (PMN) and some of the latter were seen in the vessel walls. At 24 h abundant PMN, many of them necrotic, were present in the vessel walls, apparently unable to pass through them. At 48 h numerous PMN were seen adhering to degenerating muscle fibers. By 4 days necrotic changes extended through the full thickness of the tongue, but concurrently it was observed that the larger thrombosed vessels were becoming recanalized. At 5 days repair by granulation tissue was taking place and at 6 days the vasculature was virtually reconstituted. By 14 days healing was complete.

Age-standardized incidence rates of primordial cyst (keratocyst) on the Witwatersrand

Cases of primordial cysts derived from the records of all the hospital pathology departments and private pathology practices on the Witwatersrand, were recorded for the 10-year period 1965-74. The population at risk (1970 census) was 974,390 Whites and 1,567,280 Blacks. Age-specific morbidity rates for each sex and race were calculated, as well as age-standardized incidence rates standardized against African, World and European standard populations. The age-standardized incidence rates for primordial cysts, standardized against a World standard population, per million per year are 0.61, 0, 4.86 and 3.50 for Black males and females and White males and females, respectively. In the population at risk, primordial cysts are much more common in Whites than in Blacks, the incidence being eight times higher in White males than in Black males. The present study confirms that there is a bimodal age distribution but with a higher incidence of the cyst in the age group 50-64 years than previously suspected. This may be either because a substantial number of cases remain undiagnosed for many years or because there are two groups of primordial cyst: one which is triggered in young patients and the other in older patients.

Age-standardized incidence rates of ameloblastoma and dentigerous cyst on the Witwatersrand, South Africa

Although a great deal is known about the incidence of cancer, including oral cancer, no such study has been done on odontogenic tumors and jaw cysts. There are therefore no standardized data which would allow for comparative incidences in different countries and between different groups. In the present study, cases of ameloblastomas and dentigerous cysts derived from the records of all the hospital pathology departments and private pathology practices on the Witwatersrand, were recorded for the 10-year period 1965--1974. The population at risk (1970 census) was 974,390 Whites and 1,567,280 Blacks. The annual incidence rates, standardized against the standard world population, for ameloblastomas per million population are 1.96, 1.20, 0.18 and 0.44 for Black males, females and White males, females, respectively. The equivalent four figures for dentigerous cysts are 1.18, 1.22, 9.92 and 7.26. These figures show that ameloblastoma is very much more common in Blacks than Whites in the population at risk. Conversely, dentigerous cysts are much more common in Whites. This makes it unlikely that dentigerous cysts predispose to ameloblastoma formation. These epidemiologic observations give rise to speculation as to whether some component of the South African Black diet or other environmental substance might possibly be an etiologic factor in ameloblastoma.

Radiological features of mandibular primordial cysts. (Keratocysts)

Primordial cysts (keratocysts) have been shown to have a greater tendency to recurrence than other jaw cysts. Some radiological features may assist in establishing the diagnosis. Thirteen mandibular primordial cysts have been studied radiologically in detail. Characteristic features are extension along the medulla with minimal expansion except in young children. Margins are generally sharply demaracated and either smooth or scalloped. Cortical resorption occurs before expansion. The cysts may displace adjacent teeth, particularly when unerupted, but generally do not produce root resorption. They may displace the neurovascular bundle. Antero-posterior dimensions in this series ranged from 28 to 77 mm, with a mean of 50 mm.

Estimation of the volumes of multinucleate giant cells

An estimation of the volumes of three multinucleate giant cells has been attempted by measurements of the areas of enlarged tracings of serial paraffin sections which was estimated at approximately 5 mum in scanning electron-micrographs. In addition, three-dimensional models of these tracings constructed in wax were used to estimate the volumes of the same cells by means of Archimedes' Principle. The results indicate a close correlation between the estimates derived from the two procedures and suggest that the three cells measured have a volume of the order of magnitude of 50,000 to 100,000 mum(3).

Agonist-specific refractoriness induced by isoproterenol. Studies with mutant cells

The beta-adrenergic catecholamine isoproterenol produces a large, rapid, but often a transient, elevation in cellular content of cyclic AMP. We have used the S49 mouse lymphoma cell line, in which genetic variants with specific defects in the pathway of cyclic AMP generation and function have been isolated, to study the increase and subsequent decrease in cyclic AMP levels (termed refractoriness) following incubation of cells with isoproterenol. In wild type S49 cells, isoproterenol produces a peak response in the cellular content of cyclic AMP within 30 min, but the cyclic AMP level falls rapidly thereafter, approaching basal levels by 6 h. Neither inactivation of the drug nor secretion of a nonspecific inhibitor of adenylate cyclase appears to account for the refractoriness. Because isoproterenol refractory cells can still be stimulated by cholera toxin, refractoriness to isoproterenol does not represent a generalized decrease in cellular cyclic AMP response. Particulate preparations from refractory cells have a selective loss of isoproterenol-responsive adenylate cyclase activity, but their activation constants and stereoselectivity for (-)- and (+)-isoproterenol are unaltered. In addition, refractory cells have decreased specific binding of the beta-adrenergic antagonist [125I]iodohydroxybenzylpindolol. This decrease appears to represent a reduction in the number, but not the affinity, of beta-adrenergic receptor sites. Similar studies in an S49 clone that lacks the enzyme cyclic AMP-dependent protein kinase yield essentially identical findings. Because kinase-deficient cells do not induce the cyclic AMP-degrading enzyme phosphodiesterase after the cellular content of cyclic AMP is increased, induced of phosphodiesterase cannot account for refractoriness to isoproterenol. Cyclic AMP-dependent protein kinase does not appear to be required for either the decrease in beta-adrenergic receptors and isoproterenol-responsive adenylate cyclase, nor does it appear to be required for the development of refractoriness to isoproterenol. In contrast, an S49 clone lacking hormone-responsive adenylate cyclase activity but retaining beta-adrenergic receptors does not appear to lose receptors after being incubated with isoproterenol, either alone or together with dibutyryl cyclic AMP. Therefore, in this clone, receptor occupancy alone or in combination with elevated cyclic AMP levels is insufficient to cause refractoriness. Refractoriness thus appears to require intact adenylate cyclase. This suggests that adenylate cyclase may exert regulatory controls on beta-adrenergic receptors in addition to generation of cyclic AMP.

A case report of keratoameloblastoma

In the "WHO histological typing of odontogenic tumors, jaw cysts and allied lesions", the authors recognize five distinct histologic types of ameloblastoma. A further histologic variant, the keratoameloblastoma, was first described by PINDBORG. A second case of a keratoameloblastoma is reported. This lesion occurred in the maxilla of a 28-year-old Caucasian male.

Granular cell peripheral odontogenic fibroma

A case of a peripheral odontogenic fibroma which contained aggregates of large granular cells is reported. These granular cells are similar to those previously described in the granular cell myoblastoma, congenital epulis and the granular cell ameloblastic fibroma. Deep extensions of the basal layer of overlying gingival epithelium, in double-strand fashion, are frequently observed in peripheral odontogenic fibromas. These strands closely resemble those seen in the tumor itself. On this basis, and as similar basal cell prolongations are seen in otherjaw lesions, it is postulated that residual ectomesenchymal influence may be responsible for inducing the basal cell proliferations in a similar manner to that which occurs during early embryonic dental development. This, it is suggested, might possibly be the histogenesis of the odontogenic epithelial strands in the peripheral odontogenic fibroma.

Root resorption by ameloblastomas and cysts of the jaws

Radiographs of 122 cases of a series of nonmalignant simple jaw cysts and ameloblastomas were examined and the frequency of resorption of adjacent tooth roots compared. The ameloblastomas proved to have a root resorptive potential far greater than the cystic lesions considered. Certain statistically significant differences were observed in the root resorption related to the cystic lesions. The dentigerous cyst showed a tendency to resorb roots (55%), whereas in this study no resorption was observed in primordial cysts. These differences may aid the clinician in the preoperative differential diagnosis. It is suggested that the capacity of the dentigerous cyst for root resorption may be the result of its origin from the dental follicle, which is associated with resorption of the roots of primary teeth during normal tooth succession.

The prediction of lymph node metastases from oral squamous carcinoma

In an attempt to predict which cases of oral and oropharyngeal squamous carcinoma are likely to metastasize to regional lymph nodes a series of 898 cases was grouped according to site, size, grade of histological differentiation, and presence or absence of histologically confirmed regional lymph node metastases. The results were analysed by a logistic multiple regression analysis. They showed that the sites may be divided into three clusters, Cluster 1 consists of tumors of lip, floor of mouth, cheek mucosa, hard palate, and gingiva. These are not significantly different as regards metastasis rate. Cluster 2 consists of tumors of the anterior two-thirds of tongue and has a higher tendency to metastasis than those in Cluster 1. Lesions of the posterior third of tongue and oropharynx form Cluster 3 which exhibits the greatest tendency to metastasis. Sizes of primary lesions are clustered in groups of lesions less than 3 cm, those 3 to less than 4 cm, and those 4 cm or larger, in ascending tendency to metastasis. Well-differentiated and moderately differentiated tumors are not significantly different in their tendency to metastasize and may be reduced to a single cluster, whereas poorly differentiated tumors have a markedly higher metastasis rate. Using these clusters it has been possible to predict the logistically transformed probability of metastasis to a high degree of accuracy (R=0.9398). From this we conclude that if for a given tumor we know to which site, size or differentiation cluster it belongs, we can then estimate its probability of metastasising.

Microscopic features of the lateral periodontal cyst

The lateral periodontal cyst is of developmental odontogenic origin and must be differentiated from the gingival cyst of adults, a primordial cyst in a lateral periodontal position, and a cyst of inflammatory origin. This paper is based on a histologic study of five cases. Four were in the mandibular premolar region and one in the lateral incisor-canine region of the maxilla. The cysts are lined by a thin non-keratinized epithelium which resembles the reduced enamel epithelium. Many of them arecharacterized by the presence of localized plaque-like thickenings of their epithelial linings, consisting of fusiform or large swollen, edematous cells. These epithelial thickenings appear to result from a localized proiferation of basal cells. The lateral periodontal cyst may arise initially as a dentigerous cyst which develops by expansion of the follicle along the lateral surface of the crown and comes to lie on the lateral aspect of the root if tooth eruption is normal. Alternatively, it may arise from the cell rests of Malassez.

A histological comparison of the giant cells in the central giant cell granuloma of the jaws and the giant cell tumor of long bone

A histological comparison has been made of the giant cells in 10 cases which had been diagnosed as central giant cell granuloma of the jaws and 10 cases diagnosed as giant cell tumor of long bone. The numbers of nuclei in each of 50 giant cells were counted in the 20 lesions. The giant cells were measured in order to compare their sizes in the respective lesions. It was found that the giant cells of the jaw lesions contained significantly fewer nuclei than those of the lesions in other bones. Secondly it was found that cells in the lesions of long bone have significantly larger dimensions than those in the jaw lesions. There was, however, an area of overlap. It was concluded that these data supported the view that giant cell tumor and giant cell granuloma are distinct entities. Some giant cell lesions of long bones are, however, morphologically indistinguishable from lesions of the jaws; and conversely giant cell lesions of the jaws are indistinguishable from some giant cell lesions of the long bones. It seems possible, therefore, that some jaw lesions are giant cell tumors and that some giant cell lesions outside the jaws are giant cell granulomas.