Hypothesis: Iodine, selenium and the development of breast cancer

Background: In this paper we examine some of the evidence linking iodine and selenium to breast cancer development. Seaweed is a popular dietary component in Japan and a rich source of both of these essential elements. We hypothesize that this dietary preference may be associated with the low incidence of benign and malignant breast disease in Japanese women. In animal and human studies, iodine administration has been shown to cause regression of both iodine-deficient goiter and benign pathological breast tissue. Iodine, in addition to its incorporation into thyroid hormones, is organified into anti-proliferative iodolipids in the thyroid; such compounds may also play a role in the proliferative control of extrathyroidal tissues. Selenium acts synergistically with iodine. All three mono-deiodinase enzymes are selenium-dependent and are involved in thyroid hormone regulation. In this way selenium status may affect both thyroid hormone homeostasis and iodine availability. Conclusion: Although there is suggestive evidence for a preventive role for iodine and selenium in breast cancer, rigorous retrospective and prospective studies are needed to confirm this hypothesis.     

A postprocessing dual energy technique for vertebral CT densitometry

The influence of the fat content in the cancellous bone on CT densitometry was measured on the excised vertebrae from 42 elderly human subjects. Using single energy CT, the decrease of the measured mineral content was 12% for a fat content of 10% by volume at a mean mineral content of 100-110 mg/cm3. Using a dual calibration at 85 and 130 kVp with reference to K2HPO4 for mineral and to alcohol for fat, our experiment showed that the mineral content of the vertebra can be measured with an accuracy of 6% referred to the ash-weight.     

Organising unrestricted open access gastroscopy in South Tees.

Increasing demand for upper gastrointestinal endoscopy has forced many clinicians to reconsider the policy of seeing all patients in a specialist clinic before gastroscopy. The following are considered essential in setting up an open access gastroscopy service. (1) Assessment of the need by examination of waiting times for the outpatient clinic and the proportion of patients requiring upper gastrointestinal endoscopy, and consultation with colleagues in general practice. During the first 2 years of the service the average waiting time for a medical gastrointestinal outpatient appointment has fallen from over 120 days to 37 days in this area. (2) An adequately staffed and equipped gastrointestinal unit with well motivated nurses (the workload will increase) and sufficient clinical support to allocate patients to the next available gastroscopy list is vital. A safe mechanism for relaying information back to the GP (including histology reports) is essential otherwise medicolegal problems could arise. Open access gastroscopy now accounts for 29% of the total endoscopy workload in South Tees. (3) Close cooperation between medical and surgical gastroenterologists must be achieved to ensure a uniform approach to the provision of this service and equal distribution of the endoscopy workload. This will require close examination of the potential numbers and may necessitate appointment of a clinical assistant or additional consultant. Clinical assistants perform just over 50% of the open access gastroscopies in South Tees and the waiting time has been kept short (average 17 days). (4) A comprehensive request form with guidelines for GPs and a specific box identifying whether the GP requires a report and brief advice only or follow up at the discretion of the endoscopist (often a clinical assistant) is required. (5) Management must be involved in identifying adequate resources. (6) Methods of monitoring requests and outcome measures to ensure effective audit must be established.     

Radiation brain damage induced by interstitial 125I sources: a canine model evaluated by quantitative computed tomography

The canine brain is a good model of the human brain for studying radiation damage after megavoltage x-irradiation for brain tumors. We have further developed this model to study radiation damage induced by high activity interstitial 125I sources. Removable 125I sources were implanted in normal canine brains, and doses of 1,000 to 10,000 rads were delivered to a reference point at a 10-mm radius from the source; dose rates were 35 to 40 rads/hour at the reference point. Serial quantitative analysis of tissue damage (tissue density and contrast enhancement) was done using computed tomographic scanning up to 6 months after implantation and was compared to histopathological findings after the animals were killed. At doses greater than 19,000 rads (i.e., inside the reference point), frank coagulation necrosis was observed. Pronounced vessel-related changes, manifest as areas of contrast enhancement, corresponded to tissues receiving a minimum of 6,000 rads and a maximum of 19,000 rads. These results indicate that this model can be used in serial noninvasive studies to quantify the development of damage induced by interstitial irradiation and to provide dose-response information in individual animals.     

Nuclear magnetic resonance imaging of experimentally induced liver disease

Experimental animal models of hepatitis, fatty liver, and hepatic iron overload were evaluated using a 3.5-kGauss nuclear magnetic resonance (NMR) imaging system. Increases in image intensity measurements and in T2 relaxation times equalled the sensitivity of histologic findings for the detection of early stages of hepatitis. A significant shift in T1 relaxation times characterized the early stages of hepatic necrosis. Liver triglyceride content correlated significantly with increases in NMR intensity measurements (p less than 0.01); however, changes in liver water content had a much greater influence on intensity, T1, and T2. Thus, it may be possible to distinguish hepatitis from benign fatty liver. Liver iron content correlated with decreases in NMR intensity measurements (p less than 0.001), and iron levels as low as 1.2 mg/g were detected. NMR may more specifically identify hepatocellular iron overload than do other techniques that do not distinguish hepatocellular from reticuloendothelial iron.     

Integrin alpha4beta1 (VLA-4) expression and activity in retinal and peripheral neurons

The integrin alpha4beta1 fulfills important roles in inflammation and hematopoesis, but its functions in neurons are not well understood. Here we show that the alpha4 subunit is expressed on mouse retinal ganglion cells (RGCs) and undifferentiated retinal neuroblasts during the period of axon extension and migration. To determine if alpha4 integrins expressed by retinal neurons were active, neurons were cultured on known alpha4 ligands in vitro. Recombinant soluble vascular cell adhesion molecule 1 (rsVCAM-1), fibronectin, and osteopontin (OPN) induced neurite outgrowth that was diminished by function blocking antibodies specific for alpha4. Neurite outgrowth on OPN was also blocked by antibodies to the integrin beta1 subunit, implicating the alpha4beta1 heterodimer as one integrin receptor mediating outgrowth on OPN. OPN immunoreactivity was detected in the RGC fiber layer and optic nerve, suggesting that it may act as an alpha4 ligand in vivo. Neurons from chick lumbar sympathetic ganglia, chick dorsal root ganglia, and mouse superior cervical ganglia also extended neurites on rsVCAM-1, suggesting that integrin alpha4beta1 may play a role in the development of multiple neuronal cell types.