The Mcs7 quantitative trait locus is associated with an increased susceptibility to mammary cancer in congenic rats and an allele-specific imbalance

Identification of high-penetrance breast cancer genes such as Brca1 has been accomplished by analysing familial cases. However, these genes occur at low frequency and do not account for the majority of genetic risk. Identification of low-penetrance alleles that occur commonly in populations may benefit from unbiased genome-wide screening. One such approach uses linkage studies in rodent models to identify homologous human candidates. The Wistar Kyoto (WKy) rat is resistant to mammary carcinomas induced with 7,12-dimethybenz[a]anthracene (DMBA), whereas the Wistar Furth (WF) strain is susceptible. Previous genome-wide linkage studies in crosses of these strains identified three WKy resistance quantitative trait loci, Mcs5, Mcs6 and Mcs8, and one predicted to increase susceptibility, Mcs7. The Mcs7 region on rat chromosome 10 (RNO10) is orthologous to human 17q, a common site of genetic aberrations in breast cancer. Here, we establish the independent phenotype conferred by Mcs7 using congenic rats carrying the WKy Mcs7 locus on a WF background. Tumor multiplicity was significantly higher ( approximately 50%) in DMBA-treated congenics homozygous and heterozygous for the WKy allele at the Mcs7 locus, compared to controls. We also investigated allelic imbalance (AI) in mammary carcinomas from (WKy x WF)F1 rats and Mcs7 heterozygous congenics. Of the four known WKy Mcs loci tested, only Mcs7 displayed AI. The pattern of AI in carcinomas from both F1 and Mcs7 congenic rats was similar, suggesting a WF allelic loss. Together, these data suggest that one or more breast cancer-related genes are located within the dominantly acting WKy allele at the Mcs7 locus.

The absence of the internal carotid artery: report of two cases

The absence of the internal carotid artery (ICA) is a very rare anomaly. Since the first description of the condition in 1787, only 60 cases have been reported in the literature. We report two cases of absence of the left ICA amongst 2195 carotid angiograms performed in the Department of Neuroradiology at the Royal Brisbane Hospital over a period of 4 years. The first patient was suffering from obstructive hydrocephalus; the second from right cerebellopontine angle syndrome. Cerebral angiography by catheterization of the aorta revealed the absence of the left ICA. The collateral circulation to the left cerebral hemisphere was provided by the vertebrobasilar system via a dilated left posterior communicating artery. In the first patient, the absence of the ICA was coincidental with other congenital anomalies of the cervico-occipital junction. In the second patient, the dilated vertebrobasilar system was responsible for compressing the right cranial nerves VII and VIII. It is emphasized that in some cases of cerebellopontine angle syndromes, thorough investigation of the cerebral vessels is necessary.

Clinical assessment of the elderly patient

The examination of an elderly patient often requires special techniques and attention to the patient's comfort and ease. This paper outlines a reasonable approach to each phase of the interview and discusses the particular medical problems of this age group. Older people are often slow to bring their troubles to medical attention because their symptoms are vague or because they accept their disability as part of old age. Sometimes they have difficulty in communicating effectively with the physician. Simple patience can ease an otherwise frustrating situation.

The impact of a new geriatric program in a hospital for the chronically ill

Reports of the rapidly increasing proportion of persons aged 65 years and more in Canada and the resultant need for changes in the country's health care system prompted experimental changes in the operation and training procedures at St. Mary's of the Lake Hospital, Kingston, Ont. Aimed at better patient care and at better education of medical house staff in geriatrics and long-term care, the revised program is permeated with the philosophy of rehabilitation. It includes full-time staff, a geriatric outpatient clinic, a day hospital, a team approach to patient care (with regular team audits), problem-oriented medical records, a formal physical medicine section with a district inpatient unit, and an intensive inservice education program. After the first year of the program patient outcome had improved and more efficient use was being made of continuing care beds because of larger numbers of patinets being discharged home after shorter stays. This may be one avenue for deceleration of our country's dismal rate of institutionalization.