Age-related alterations of NMDA-receptor properties in the mouse forebrain: partial restoration by chronic phosphatidylserine treatment.

The effect of aging on the properties of N-methyl-D-aspartate (NMDA) receptors in the forebrain of female NMRI mice was investigated using the antagonist [3H]MK-801 as radioligand. Compared to young (3 months) mice, aged (20 months) mice showed changes of the properties of the NMDA receptor at three different levels: (1) the density was reduced by about 35%; (2) the efficacy of L-glutamate and glycine for stimulating specific [3H]MK-801 binding was enhanced, probably because more NMDA receptor-associated ion channels are closed under baseline conditions in the aged brain; (3) the affinity of L-glutamate and glycine to its binding sites at the NMDA receptor complex was also enhanced. Chronic treatment of aged mice with phosphatidylserine (20 mg/kg, i.p., once daily) for three weeks completely normalized enhanced efficacy and affinity of L-glutamate and glycine and elevated NMDA receptor density by approximately 25%. These findings are consistent with the assumptions that deficits of the NMDA receptor are one of the mechanisms of age-related cognitive impairment and that the beneficial effects of phosphatidylserine treatment on cognitive deficits of aged individuals might be partially due to the effects of this drug on age-related NMDA receptor deficits.     

Limited lists and the purchase of pharmaceutical products by government agencies in the RSA

The use of a limited list to restrict the range and type of medication used by medical institutions that operate under the auspices of the provincial authorities has been mooted as one possible method of cost containment. This study discusses the implementation of such measures in other countries and then quantifies the cost savings that might be obtained in the South African case. The possible savings are somewhat offset by other costs such a measure would introduce.     

Nasal secretory response to allergen provocation

Nasal provocation with ragweed pollen extract was performed on ragweed-sensitive and non-atopic subjects. Nasal lavage fluids were collected 15 min after saline and allergen challenges, and assayed for total protein, albumin, potassium, lysozyme activity and peroxidase activity. There was no statistically significant increase in any of these lavage fluid constituents in non-atopic subjects after allergen provocation, compared with after saline provocation. The lavage fluids of ragweed-sensitive subjects had significant rises in each of the constituents following allergen provocation. This method provides a simple mechanism for quantitating the nasal secretory response to allergen provocation.     

Myxofibroma of the maxilla: a case report with computed tomogram findings

A rare case of a large myxofibroma of the maxilla is presented. Computerized tomographic features, in conjunction with clinical appearance, were highly suggestive of a definitive diagnosis. Computerized tomography may play an important role in the planning of surgical management of this tumor known for its local aggressiveness and high recurrence rate.     

Acute effects of high-dose thyrotropin releasing hormone infusions in Alzheimer's disease

Thyrotropin releasing hormone (TRH) was administered intravenously to ten patients with Alzheimer's Disease (AD) in a high-dose paradigm, thought to maximize central nervous system effects and potentially produce facilitation of cholinergic function, a known property of the neuropeptide. Acute effects of TRH on behavioral, cognitive and physiologic measures were assessed after patients received 0.1 mg/kg TRH, 0.3 mg/kg TRH and placebo, the higher TRH dose and placebo being given in a randomized, double-blind fashion. Patients showed statistically significant increases in arousal and improvement in affect, as well as a modest improvement in semantic memory, all after receiving the higher TRH dose. Both TRH doses produced transient rises in systolic blood pressure, with no effect on diastolic blood pressure, heart rate or temperature. This study suggests that high-dose TRH can be safely administered to AD patients and is neurobehaviorally active; further studies are needed to determine the extent and mechanism of the cognitive and psychobiological properties of this peptide in AD and other neuropsychiatric disorders.