Carcinomatosis of the Meninges

Some clinical and pathological features of carcinomatosis of the meninges are reviewed along with a report of four cases. This condition usually presents in middle age as a subacute meningitis with cranial nerve involvement, but the diagnostic importance of the various mental disturbances which may be encountered early in its course are noted. The acute or subacute course may reflect a widespread mechanical interference with normal cerebral metabolism, a notion which is supported by recent clinical measurements in these patients of the rate of glucose transport across the blood-brain barrier. It is probable that the route taken by tumour cells to reach the meningeal spaces is a relatively unimportant factor in determining this pattern of growth and that the intrinsic growth characteristics of the primary tumour, its nutritional needs, and gravity probably play the major roles in production of this unusual type of secondary invasion. Greater therapeutic use of irradiation for these patients is encouraged.     

Meningeal worm in deer from western Nebraska

One hundred seventy-eight white-tailed deer (Odocoileus virginianus) and 275 mule deer (Odocoileus hemionus) collected from locker plants in the western 2/3 of Nebraska (USA) in November 1997 were examined for the meningeal worm (Parelaphostrongylus tenuis). Parelaphostrongylus tenuis was identified in 17 (10%) of 168 white-tailed deer and in one (<1%) of 273 mule deer. This is the first naturally occurring infection of P. tenuis recorded in a mule deer.     

Meningeal worm in free-ranging deer in Nebraska

The meningeal worm (Parelaphostrongylus tenuis) was found in 22 (7%) of 300 white-tailed deer (Odocoileus virginianus) (257 adults, 43 fawns) examined from Nebraska (USA) during November 1996. None of 53 mule deer (Odocoileus hemionus) (47 adults and 6 fawns) examined were infected. Twenty-two white-tailed deer from 18 counties in eastern Nebraska were infected with Parelaphostrongylus tenuis. This is the first record of P. tenuis in white-tailed deer from this state.     

Meningeal calcification of the rat pineal organ

Summary The surface of the pineal organ of the rat is covered by a leptomeningeal tissue, the continuation of the corresponding meningeal layers of the diencephalon. The pineal leptomeninx consists of stratified arachnoid and of pia mater cells which follow the vessels into the pineal nervous tissue. The pineal arachnoid contains electron-lucent and electron dense cells differing from each other in their cytoplasmic components. Corpora arenacea of various size and density occur among these arachnoid cells and can grow into the pineal organ alongside pia mater tissue. Acervuli often form groups in circumscribed meningeal calcification foci. Concrements are absent or rare in the 1- and 2-month-old animal, while they are usually present in the 4- and 6-month-old rats.The electronmicroscopic localization of Ca-ions was studied in 2- and 4-month-old rats by potassium pyroantimonate cytochemistry. In the 4-month-old animals, arachnoid cells containing a varying amount of Ca-pyroantimonate deposits were found first of all around corpora arenacea, but there were also cells free of deposits in the close vicinity of the acervuli. Deposits were preferentially localized to the cytoplasm of electron dense arachnoid cells and to the cell membrane of electron-lucent cells. Most of the precipitates occurred in locally enlarged intercellular spaces. Here, microacervuli were found in 4-month-old animals suggesting that a calcium-rich environment was responsible for the appearance of the concrements. Intermediate stages between the small acervuli and large concentric corpora arenacea may indicate an appositional growth of the acervuli in the calcification foci. Occasionally, acervuli were also located inside meningeal cells.There was no sign of the formation of acervuli in the pinealocytes or elsewhere in the pineal nervous tissue proper, in the age interval (1- to 6-month-old animals) studied. These findings confirm the view that corpora arenacea can be produced in the rat by the pineal leptomeninx. The laboratory rat seems to be usefull in studying pineal calcification of the meningeal type.Supported by the Hungarian OTKA grant Nr. 1619 to B.V.     

Photoimmunotherapy of Gastric Cancer Peritoneal Carcinomatosis in a Mouse Model

Photoimmunotherapy (PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. We performed PIT in a model of disseminated gastric cancer peritoneal carcinomatosis and monitored efficacy with in vivo GFP fluorescence imaging. In vitro and in vivo experiments were conducted with a HER2-expressing, GFP-expressing, gastric cancer cell line (N87-GFP). A conjugate comprised of a photosensitizer, IR-700, conjugated to trastuzumab (tra-IR700), followed by NIR light was used for PIT. In vitro PIT was evaluated by measuring cytotoxicity with dead staining and a decrease in GFP fluorescence. In vivo PIT was evaluated in a disseminated peritoneal carcinomatosis model and a flank xenograft using tumor volume measurements and GFP fluorescence intensity. In vivo anti-tumor effects of PIT were confirmed by significant reductions in tumor volume (at day 15, p<0.0001 vs. control) and GFP fluorescence intensity (flank model: at day 3, PIT treated vs. control p<0.01 and peritoneal disseminated model: at day 3 PIT treated vs. control, p<0.05). Cytotoxic effects in vitro were shown to be dependent on the light dose and caused necrotic cell rupture leading to GFP release and a decrease in fluorescence intensity in vitro. Thus, loss of GFP fluorescence served as a useful biomarker of cell necrosis after PIT.     

Meningeal mycosis fungoides: cytologic and ultrastructural aspects.

Mycosis cells were identified in the pre-morbid cerebrospinal fluid of a patient with neurological symptoms and mycosis fungoides (MF). Light and electron microscopic examination at autopsy confirmed leptomeningeal involvement by mycosis fungoides. The cellular morphology of the non-cutaneous infiltrates supports the concept that mycosis fungoides retains a unique histopathology in its dissemination to the viscera. The importance of cerebrospinal fluid cytology in patients with mycosis fungoides is emphasized.     

Meningeal worm in a reintroduced elk population in Kentucky

Meningeal worm (Parelaphostrongylus tenuis) has been implicated in the failure of several elk (Cervus elaphus) restoration attempts in the eastern United States. However, limited post-release monitoring and a paucity of published literature prevents a clear understanding of this parasite's role in past failures. During winters of 1997-2001, the Kentucky Department of Fish and Wildlife Resources translocated 1,044 elk from western states to eastern Kentucky (USA) in an effort to restore a free-ranging population. We monitored 521 radio-collared elk over 4 yr to determine the impact meningeal worm had on population establishment. Thirty (23%) of 129 non-capture related mortalities were attributed to meningeal worm. Twenty-two (73%) of these meningeal worm-caused mortalities were animals < 3 yr old. If younger elk born in Kentucky suffer higher mortality rates than older translocated elk, the population growth observed during the initial years of restoration may be temporary. Additional research is necessary to determine the influence meningeal worm will have on elk population growth in Kentucky.