Biomedical subjects
Publications and source records attributed to R Pamphlett.
A metastasis from a carcinoma of the lung to an intracranial meningioma is described. This event is being reported more frequently, with most cases being seen since 1970. In patients with carcinoma, biopsies of intracranial tumours should include hyper- or hypodense regions in the tumour seen on CT.
Deafness occasionally results from bilateral lesions of the temporal lobes. Conventional methods of assessing hearing are not helpful in the diagnosis of this condition. We describe the case of a patient who exhibited the hallmark of a cortical hearing disorder--he was able to hear simple sounds, but could not make sense of complex sounds such as speech and music.
A father and daughter were each found to have an olfactory groove meningioma. No members of the family were found to have neurofibromatosis. There have been 4 previous reports of meningiomas occurring in families, and the present report adds support to the hypothesis that meningioma can be a heredofamilial disorder.
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The histochemical silver amplification technique autometallography (AMG), was used to trace bismuth in the testis of Wistar rats injected intraperitoneally with bismuth subnitrate. In the seminiferous tubules, bismuth was located in lysosomes of Sertoli cells closely associated with heads of spermatids in the late stages of the spermatogenesis, i.e. shortly before the release of Step 19 spermatids in Stage XIII. No bismuth-specific AMG silver grains were detected in the spermatogenic cell line. However, tails of free sperm cells located in the tubular lumen showed autometallographic grains in close contact to the nine outer microtubule doublets in the axonema. Leydig cells concentrated huge amounts of AMG-bismuth in their lysosomes. Furthermore, parallel exposure to selenium significantly increased the amount of histochemically traceable bismuth in the rat testis.
Bismuth, a component of many gastrointestinal medications, is a heavy metal little studied as regards nervous system uptake. We were interested to see if low doses of intragastric bismuth entered the nervous system, and if dietary selenium influenced the amount of bismuth detected. Mice were given 40 to 1200 mg/kg of bismuth subnitrate (BSN), bismuth subsalicylate (BSS), colloidal bismuth subcitrate (CBS), or ranitidine bismuth citrate (RBC) intragastrically. Mice on low- or high-selenium diets were given 4 to 32 mg/kg of bismuth from RBC. One week later, sections of nervous tissue were stained with autometallography to detect bismuth grains (Bi(AMG)). Bismuth was found in neurons with axons outside of the nervous system, in particular motor neurons, and in cells outside the blood-brain barrier. The lowest bismuth dose which resulted in Bi(AMG) in motor neurons was 696 mg/kg from BSN, 57 mg/kg from BSS, 29 mg/kg from CBS, and 26 mg/kg from RBC. No bismuth was seen in motor neurons of mice on the low-selenium diet. Intragastric doses of bismuth therefore enter mouse motor neurons, and the amount detectable varies with dietary selenium.
The localisation of mercury in the developing nervous system following mercury vapor (Hg(0)) exposure is not clear. We therefore looked for mercury in the mouse nervous system following fetal or neonatal exposure to Hg(0). Mice were exposed to 50 or 500 microg/m(3) Hg(0) for 4 h a day for 5 days in late pregnancy, and pups sacrificed on postnatal day (P)1 or P40. Neonatal mice were exposed to 500 microg/m(3) Hg(0) for 2 h between P1 and P23, and were sacrificed 2 days later or at P40. Paraffin sections of the nervous system were stained with autometallography to detect inorganic mercury. No mercury was seen in the nervous system of pups after fetal exposure to the 50 microg/m(3) Hg(0) dose rate. After fetal exposure to the 500 microg/m(3) Hg(0) dose rate, mercury was seen in nervous system blood vessels and sensory ganglia. No mercury was seen in the nervous system after neonatal exposure to 500 microg/m(3) Hg(0) for 2 h between P1 and P10. From this exposure at P11 onwards, mercury was detected in motor neurons. The lack of stainable mercury in early developing central neurons suggests that the fetal and neonatal nervous systems are somehow protected from Hg(0) uptake.
Gender differences have been noted in the tissue distribution of mercury. We sought to determine if the uptake of low-dose inorganic mercury into motor neurons differs between male and female mice. Four male and four female mice were injected i.p. with 0.5 mg HgCl2/kg. In 50-microns sections of lumbar spinal cord stained with autometallography, six motor neuron cell bodies were selected for study. The volume percentage of mercury granules in the cell bodies was estimated using a confocal microscope. Mercury granules occupied more perikaryal volume in motor neurons from female mice (mean 3.7%) than from male mice (mean 2.2%) (p < or = 0.05). After the same dose, the amount of renal mercury measured by mass spectrometry was significantly less in six female than five male mice. In conclusion, female mice take up more inorganic mercury into their motor neurons than do male mice. This may be related to a smaller deposition of mercury in the female kidney, leaving more circulating mercury available to be taken up by motor axons.
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