Aging alters mRNA expression of amyloid transporter genes at the blood-brain barrier.

Decreased clearance of potentially toxic metabolites, due to aging changes, likely plays a significant role in the accumulation of amyloid-beta (Aß) peptides and other macromolecules in the brain of the elderly and in the patients with Alzheimer's disease (AD). Aging is the single most important risk factor for AD development. Aß transport receptor proteins expressed at the blood-brain barrier are significantly altered with age: the efflux transporters lipoprotein receptor-related protein 1 and P-glycoprotein are reduced, whereas the influx transporter receptor for advanced glycation end products is increased. These receptors play an important role in maintaining brain biochemical homeostasis. We now report that, in a rat model of aging, gene transcription is altered in aging, as measured by Aß receptor gene messenger RNA (mRNA) at 3, 6, 9, 12, 15, 20, 30, and 36 months. Gene mRNA expression from isolated cerebral microvessels was measured by quantitative polymerase chain reaction. Lipoprotein receptor-related protein 1 and P-glycoprotein mRNA were significantly reduced in aging, and receptor for advanced glycation end products was increased, in parallel with the changes seen in receptor protein expression. Transcriptional changes appear to play a role in aging alterations in blood-brain barrier receptor expression and Aß accumulation.

P-glycoprotein expression and amyloid accumulation in human aging and Alzheimer's disease: preliminary observations.

P-glycoprotein (P-gp), part of the blood-brain barrier, limits drug access to the brain and is the target for therapies designed to improve drug penetration. P-gp also extrudes brain amyloid-beta (Aß). Accumulation of Aß is a hallmark of Alzheimer's disease (AD). Aß accumulates in normal aging and in AD primarily due to decreased Aß clearance. This is a preliminary report on the relative protein and messenger RNA expression of P-gp in human brains, ages 20-100 years, including AD subjects. In these preliminary studies, cortical endothelial P-gp expression decreased in AD compared with controls (p < 0.001). Trends in P-gp expression in human aging are similar to aging rats. Microvessel P-gp messenger RNA remained unchanged with aging and AD. Aß plaques were found in 42.8% of normal subjects (54.5% of those older than 50 years). A qualitative analysis showed that P-gp expression is lower than the group mean in subjects older than 75 years but increased if younger. Decreased P-gp expression may be related to Aß plaques in aging and AD. Downregulating P-gp to allow pharmaceuticals into the central nervous system may increase Aß accumulation.

Amyloid-beta accumulation, neurogenesis, behavior, and the age of rats.

The goals of this research were to describe age-related changes in brain biochemistry and behavior, and the relationships between them. The chronological ages of greatest change are particularly important for targeting interventions. In this experiment, 36 Fischer 344/Brown-Norway rats (3, 12, 20, and 30 months old) were trained in lever boxes on temporal discrimination tasks. The greatest response rate decrease and response pattern change occurred between 12 and 20 months. The biochemical results showed that amyloid-beta peptides (Aß40 and Aß42) increased with age. The endothelial expression of the Aß influx transporter (RAGE) also increased, and the expression of Aß efflux transporter (LPR-1) decreased, with age. The greatest change in the biochemical measures also were between 12 and 20 months. Twenty additional rats were analyzed for stem cell proliferation, and neurogenesis decreased with age, particularly between about 12 and 20 months. These early changes in brain, biochemistry, and behavior provide opportunity for new therapies or prophylaxis.

The utility of ionotropic glutamate receptor antagonists in the treatment of nociception induced by epidural glutamate infusion in rats.

BACKGROUND: The authors have previously demonstrated that human herniated disc material contains high concentrations of free glutamate. In an experimental model, elevated epidural glutamate concentrations in the lumbar spine can cause a focal hyperesthetic state. METHODS: Rats underwent epidural glutamate infusion in the lumbar spine by a miniosmotic pump over a 72-hour period. Some rats underwent coinfusion with glutamate and ionotropic glutamate antagonists. Nociception was assessed by von Frey fibers and by assessment of glutamate receptor expression in the corresponding dorsal horn of the spinal cord. RESULTS: The kainic acid antagonist, UBP 301, decreased epidural glutamate-based hyperesthesia in a dose dependent manner. Concordant with these findings, there was significant decrease in kainate receptor expression in the dorsal horn. The N-Methyl-4-isoxazoleproionic acid (NMDA) antagonist Norketamine also significantly diminished hyperesthesia and decreased receptor expression in the dorsal horn. CONCLUSIONS: Both UBP 301, the kainic acid receptor antagonist and Norketamine, an NMDA receptor antagonist, dampened epidural glutamate-based nociception. Focal epidural injections of Kainate or NMDA receptor antagonists could be effective treatments for disc herniation-based lumbar radiculopathy.

Anti-KIT designer T cells for the treatment of gastrointestinal stromal tumor.

BACKGROUND: Imatinib mesylate is an effective treatment for metastatic gastrointestinal stromal tumor (GIST). However, most patients eventually develop resistance and there are few other treatment options. Immunotherapy using genetically modified or designer T cells (dTc) has gained increased attention for several malignancies in recent years. The aims of this study were to develop and test novel anti-KIT dTc engineered to target GIST cells. METHODS: Human anti-KIT dTc were created by retroviral transduction with novel chimeric immune receptors (CIR). The gene for stem cell factor (SCF), the natural ligand for KIT, was cloned into 1st generation (SCF-CD3ζ, 1st gen) and 2nd generation (SCF-CD28-CD3ζ, 2nd gen) CIR constructs. In vitro dTc proliferation and tumoricidal capacity in the presence of KIT+ tumor cells were measured. In vivo assessment of dTc anti-tumor efficacy was performed by treating immunodeficient mice harboring subcutaneous GIST xenografts with dTc tail vein infusions. RESULTS: We successfully produced the 1st and 2nd gen anti-KIT CIR and transduced murine and human T cells. Average transduction efficiencies for human 1st and 2nd gen dTc were 50% and 42%. When co-cultured with KIT+ tumor cells, both 1st and 2nd gen dTc proliferated and produced IFNγ. Human anti-KIT dTc were efficient at lysing GIST in vitro compared to untransduced T cells. In mice with established GIST xenografts, treatment with either 1st or 2nd gen human anti-KIT dTc led to significant reductions in tumor growth rates. CONCLUSIONS: We have constructed a novel anti-KIT CIR for production of dTc that possess specific activity against KIT+ GIST in vitro and in vivo. Further studies are warranted to evaluate the therapeutic potential and safety of anti-KIT dTc.

Excrescence of neurotransmitter glutamate from disc material has nociceptive qualities: evidence from a rat model.

BACKGROUND CONTEXT: The authors have previously demonstrated that herniated human lumbar disc is rich in free glutamate from degradation of aggrecan. Prior data have suggested that free glutamate could contribute to a nociceptive state. PURPOSE: Previous behavioral experiments suggested glutamate-related nociception by comparing pre- and postglutamate infusion responses only. This indirectly suggested nociceptive effects of epidural glutamate but was not a definitive evidence. Now, by using larger numbers of subjects, we have demonstrated that lumbar epidural glutamate infusion causes significant left-to-right differences in hind paw response during treatment, demonstrating more directly the focal nociceptive effects of glutamate. STUDY DESIGN: Behavioral studies and immunohistochemistry were used to assess for evidence of a nociceptive state. All researchers were blinded to infusion solution. METHODS: Via an implanted mini osmotic pump, the epidural space of rats was infused with 0.02 mM glutamate or normal saline for 72 hours. Signs of nociception were assessed by von Frey and plantar thermal stimulation testing and by glutamate receptor expression in the corresponding dorsal horn of the spinal cord and dorsal root ganglion. RESULTS: Both von Frey mechanical and plantar thermal stimulations showed differences in hind paw reactivity depending on whether it was on the ipsilateral or contralateral side of glutamate infusion. Saline infusion had no significant behavioral effects. Dorsal horn expression of 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl) propanoic acid and N-methyl-d-aspartic acid receptors was significantly increased in glutamate-infused animals, further indicative of a nociceptive state related to glutamate infusion. CONCLUSIONS: Elevated epidural glutamate concentrations caused a focal hyperesthetic state. Increased epidural glutamate concentration could be a driving force or "chemical" component of disc-related radiculopathy.

Study of diet-induced changes in lipoprotein metabolism in two strains of Golden-Syrian hamsters.

The objective of this study was to characterize two strains of Golden-Syrian hamsters for use in the study of diet-induced changes in lipoprotein metabolism. In Experiment 1, the time course and response to dietary saturated fat was investigated for serum lipoprotein profiles and aortic lesion formation in Golden-Syrian hamsters from Charles River Laboratories, Wilmington, MA (CR) and Bio Breeders, Watertown, MA (F(1)B). Hamsters were fed a nonpurified diet containing 10 g/100 g saturated fat and 0.1 g/100 g dietary cholesterol. After 12 wk, CR hamsters had significantly lower serum total and non-HDL cholesterol (TC and nHDL-C) levels, but higher aortic cholesteryl ester (CE) than the F(1)B hamsters (P < 0.05). In Experiment 2, CR hamsters were fed a nonpurified diet containing 10 g/100 g saturated fat and 0.1, 0.5 or 1 g/100 g dietary cholesterol. After 10 wk of dietary intervention, TC and nHDL-C levels were significantly higher in the 0.5 and 1.0 g/100 g cholesterol groups than in the 0.1 g/100 g cholesterol group. These levels declined after 20 wk of dietary intervention in all groups, potentially reflecting the toxic effect of high cholesterol intakes. CR hamsters fed a 10 g/100 g saturated fat containing 0.1 g/100 g dietary cholesterol for 10 wk appear to be a good model for investigating diet-induced change in plasma lipids.

IGF-I receptor mutations resulting in intrauterine and postnatal growth retardation.

BACKGROUND: Approximately 10 percent of infants with intrauterine growth retardation remain small, and the causes of their growth deficits are often unclear. We postulated that mutations in the gene for the insulin-like growth factor I receptor (IGF-IR) might underlie some cases of prenatal and postnatal growth failure. METHODS: We screened two groups of children for abnormalities in the IGF-IR gene. In one group of 42 patients with unexplained intrauterine growth retardation and subsequent short stature, we used single-strand conformation polymorphism analysis, followed by direct DNA sequencing of any abnormalities found. A second cohort consisted of 50 children with short stature who had elevated circulating IGF-I concentrations. Complete sequencing of the IGF-IR gene was performed with DNA from nine children. We also studied a control group of 43 children with normal birth weights. RESULTS: In the first cohort, we identified one girl who was a compound heterozygote for point mutations in exon 2 of the IGF-IR gene that altered the amino acid sequence to Arg108Gln in one allele and Lys115Asn in the other. Fibroblasts cultured from the patient had decreased IGF-I-receptor function, as compared with that in control fibroblasts. No such mutations were found in the 43 controls. In the second group, we identified one boy with a nonsense mutation (Arg59stop) that reduced the number of IGF-I receptors on fibroblasts. Both children had intrauterine growth retardation and poor postnatal growth. CONCLUSIONS: Mutations in the IGF-IR gene that lead to abnormalities in the function or number of IGF-I receptors may also retard intrauterine and subsequent growth in humans.

Genetic variation at the scavenger receptor class B type I gene locus determines plasma lipoprotein concentrations and particle size and interacts with type 2 diabetes: the framingham study.

The scavenger receptor class B type I (SR-BI) is a key component in the reverse cholesterol transport pathway. We have previously reported three common polymorphisms associated with plasma lipids and body mass index. We hypothesized that diabetic status may interact with these polymorphisms in determining plasma lipid concentrations and particle size. We evaluated this hypothesis in 2463 nondiabetic (49% men) and 187 diabetic (64% men) participants in the Framingham Study. SR-BI and APOE genotypes, anthropometric, clinical, biochemical, and lifestyle variables were determined. After multivariate adjustment, we found a consistent association between the exon 8 polymorphism and high-density lipoprotein cholesterol concentration and particle size. Interaction effects were not significant for exon 8 and intron 5 polymorphisms. However, we found statistically significant interactions between SR-BI exon 1 genotypes and type 2 diabetes, indicating that diabetic subjects with the less common allele (allele A) have lower lipid concentrations. For low-density lipoprotein cholesterol, the adjusted means (+/-SE) were 3.31 +/- 0.03 and 3.29 +/- 0.04 mmol/liter for G/G and G/A or A/A in nondiabetics, respectively, compared with 3.19 +/- 0.10 and 2.75 +/- 0.01 mmol/liter for G/G and G/A or A/A in diabetics (P = 0.03 for interaction). Similar results were obtained for HDL(2)-C. In conclusion, SR-BI gene variation modulates the lipid profile, particularly in type 2 diabetes, contributing to the metabolic abnormalities in these subjects.