Enhancement of mammary carcinogenesis by high levels of dietary fat: a phenomenon dependent on ad libitum feeding.

Female 55-day-old Sprague-Dawley rats were treated with a single intravenous dose of 7,12-dimethylbenzanthracene (DMBA), 2 mg/100 g of body weight each. At 60 days of age, the rats were divided into four dietary groups (41-42 rats/group):I, 5% corn oil diet fed ad libitum; II, 20% corn oil diet fed ad libitum; III, 5% corn oil diet fed 12% less than group I; and IV, 20% corn oil diet fed 12% less than group II. The 5% and 20% corn oil diets were purified semisynthetic diets that were isonutrient on a caloric basis. All animals were housed individually in single cages; food consumption of each animal was computed daily throughout the study. Sixteen weeks after carcinogen treatment, mean numbers of mammary carcinomas per rat (+/- SE) in groups I, II, III, and IV were 4.1 +/- 0.6, 6.8 +/- 0.7, 3.0 +/- 0.3, and 4.1 +/- 0.5, respectively. Mean weight of mammary carcinomas per rat (g +/- SE) in groups I, II, III, and IV were 3.5 +/- 0.7, 8.0 +/- 1.3, 3.0 +/- 1.1, and 4.6 +/- 1.3, respectively. Mammary carcinoma number and weight were significantly (P less than .01) increased in the animals fed the 20% corn oil diet ad libitum when compared with those fed the 5% corn oil diet ad libitum; however, no significant differences in mammary tumor number or weight were observed between the animals fed a restricted, 20% corn oil diet and those fed a restricted, 5% corn oil diet. The study involving the animals fed the 12%-restricted diets was repeated (38-42 rats/group), with virtually identical results, i.e., the mean number of mammary carcinomas per rat in the groups fed the restricted 5% fat and 20% fat diets at termination of the study was 3.1 +/- 0.4 and 3.7 +/- 0.3, respectively, and the mean weight (g) of mammary carcinomas per rat was 4.3 +/- 1.2 and 4.0 +/- 1.1, respectively (no significant differences). Thus, high levels of dietary fat can significantly enhance mammary carcinogenesis in female rats, but only in animals on an ad libitum feeding protocol. A slight restriction in amount consumed (12% less than ad libitum) abolished the mammary carcinogenic differential between a high-fat and a low-fat diet.

Current diagnosis of acoustic tumors.

This article discusses the most direct and cost-effective means of diagnosing acoustic tumors. The sensitivity and specificity of current diagnostic tests are reviewed. Newer techniques, including magnetic resonance imaging (MRI), have changed the diagnosis of acoustic neurinomas. Our current recommendation is to do a screening auditory brainstem evoked response (ABR) if the neurotologic examination and audiometry indicate a possibility of tumor. If the audiogram and examination indicate a high probability of tumor, we may proceed directly to magnetic resonance scanning.

Primary CNS tumors presenting as cerebellopontine angle tumors.

Adult patients with posterior fossa tumors arising from the cerebellum and brainstem are reported. In each case the tumor presented as a cerebellopontine angle tumor and not as an intra-axial tumor. Tumors of CNS origin are uncommon in the posterior fossa in adults, but they may be seen by the otologist if the presenting symptoms are audiologic or vestibular. Computed tomography scanning will not always distinguish these lesions from the much more common extraaxial neurinoma, meningioma, or cholesteatoma. The progression of symptoms is more rapid in these patients, and other associated neurologic deficits are more common. The auditory brainstem response may demonstrate characteristic abnormalities in these patients. The differential diagnosis of these tumors in adults is discussed and the recent literature reviewed.

A microbipolar cautery for use in the middle ear.

This delicate microscopic bipolar forceps allows very precise cautery without significant current flow to adjacent tissue. Wet-field cautery is possible; it prevents overheating of adjacent tissue. This forceps is relatively inexpensive and utilizes a standard bipolar cautery unit and cord.

Cholesterol granuloma of the cerebellopontine angle.

Two unusual cases of cholesterol granuloma of the temporal bone manifested as cerebellopontine angle tumors. To our knowledge, cerebellopontine angle extension of this lesion has not previously been reported. Obstruction of ventilation and drainage of any air complex in the temporal bone may produce cholesterol granuloma. Asymptomatic involvement of the mastoid air cell system is common in chronic otitis media. Surgical management of cholesterol granuloma with cerebellopontine angle extension is recommended. Total excision of the lesion is preferred; marsupialization into the mastoid air cell system is an alternative if excision would produce a major neurologic deficit.

Invasive mycotic infections in the immunocompromised child.

Oncologic therapy creates a highly vulnerable group of children with little or no natural immunity. In addition to the problems of coagulopathies, these children are prone to unusual infectious diseases. One group of saprophytic infections, the mycotic organisms, represents stubborn and often lethal diseases challenging present diagnostic and therapeutic skills. This is a case report of invasive Aspergillus organisms in the nose and premaxilla in a 9-year-old child suffering from acute monocytic leukemia.