Targeting Topics: Recent Scientific References

as seen in Targeting Trends Newsletter, Jan-Feb-Mar 2008

   
   
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Conjugation of an anti transferrin receptor IgG3-avidin fusion protein with biotinylated saporin results in significant enhancement of its cytotoxicity against malignant hematopoietic cells

Daniels TR, Ng PP, Delgado T, Lynch MR, Schiller G, Helguera G, Penichet ML

Mol Cancer Ther 6(11):2995-3008, 2007.

The human transferrin receptor (hTfR) is overexpressed in malignant cells. Using Advanced Targeting System's custom biotinylation service, the authors combined an anti-hTfR antibody-avidin fusion protein with biotinylated saporin (Cat. #PR-01, saporin alone), and examined the effect of the combined complex on cancer cells in vitro. Although the antibody-avidin fusion protein has an intrinsic cytotoxic effect, the fusion protein-saporin complex was able to eliminate the population of cells that showed resistance to the fusion protein alone.

Selective immunolesion of cholinergic neurons leads to long-term changes in 5-HT2A receptor levels in hippocampus and frontal cortex

Severino M, Pedersen AF, Trajkovska V, Christensen E, Lohals R, Veng LM, Knudsen GM, Aznar S

Neurosci Lett 428(1):47-51, 2007.

Changes in several neurotransmitter systems, including serotonin and 5HT2A receptors, are associated with early Alzheimer's disease (AD). The authors gave rats intracerebroventricular injections of either 2.5 or 5 µg of 192-IgG-SAP (Cat. #IT-01) then examined both of these systems. 5HT2A receptor levels were markedly decreased in the frontal cortex and markedly increased in the hippocampus of animals lesioned with 5 µg of 192-IgG-SAP. The change in 5HT2A receptor number suggests that the AD effect stems from interaction with the cholinergic system.

The role of the nucleus basalis of Meynert and reticular thalamic nucleus in pathogenesis of genetically determined absence epilepsy in rats: A lesion study

Berdiev RK, Chepurnov SA, Veening JG, Chepurnova NE, van Luijtelaar G

Brain Res 1185:266-274, 2007.

Absence seizures due to epilepsy usually occur during passive behavior. This work investigated the role of the cholinergic nucleus basalis of Meynert (NB) and the reticular thalamic nucleus (RT) in these seizures. Rats received either 75 ng of 192-IgG-SAP (Cat. #IT-01) or the control, mouse IgG-SAP (Cat. #IT-18), into the NB and the RT. Loss of cholinergic neurons in the NB resulted in an increased number of spike-and-wave discharges, a marker for absence seizures.

Food-elicited increases in cortical acetylcholine release require orexin transmission

Frederick-Duus D, Guyton MF, Fadel J

Neuroscience 149(3):499-507, 2007.

In these experiments the authors examine the hypothesis that orexin fibers from the hypothalamus are necessary for basal forebrain cholinergic system (BFCS) activation in a food restriction model. Rats received 200 ng of orexin-SAP (Cat. #IT-20) into the lateral hypothalamus/perifornical area. Lesioned animals that were also deprived of food displayed increased feeding latency when presented with food. These and other data indicate orexin in the BFCS is involved in attention to stimuli associated with homeostatic challenges.

Lesions of the basal forebrain impair reversal learning but not shifting of attentional set in rats

Tait DS, Brown VJ

Behav Brain Res 187(1):100-108, 2008.

The authors compared specific lesions of the basal forebrain using 192-IgG-SAP (Cat. #IT-01) with non-specific lesions generated by ibotenic acid. Rats were given 0.12 µg per 0.5 µl bilateral injections of 192-IgG-SAP. The treated animals were then tested in food reward tasks involving two-choice discriminations and reversal of stimulus-reward. Animals with specific lesions did not show impairment with any of the tasks suggesting that non-cholinergic neurons are involved in reversal learning. This work also demonstrates the similarities between monkey and rodent basal forebrain function.

Amyloid beta protein modulates glutamate-mediated neurotransmission in the rat basal forebrain: involvement of presynaptic neuronal nicotinic acetylcholine and metabotropic glutamate receptors

Chin JH, Ma L, MacTavish D, Jhamandas JH

J Neurosci 27(35):9262-9269, 2007.

This work focused on the effect of amyloid beta on glutamate-mediated neurotransmission in the diagonal band of Broca. Using neurons identified by staining with Cy3-labeled 192-IgG (Cat. #FL-01, 5 µl of 1:1 diluted antibody injected into the left and right ventricle) the authors monitored the response to amyloid beta by measuring excitatory postsynaptic currents via whole-cell patch-clamp recordings. The results suggest that glutamate neurotransmission might be vulnerable to Alzheimer's disease, and may also be a therapeutic target.

Effects of saporin-induced lesions of three arousal populations on daily levels of sleep and wake

Blanco-Centurion C, Gerashchenko D, Shiromani PJ

J Neurosci 27(51):14041-14048, 2007.

Orexin neurons in the basal forebrain, tuberomammillary nucleus (TMN), and locus ceruleus (LC) are thought to regulate arousal. Rats were injected with two or three of the following targeted conjugates: anti-DBH-SAP (Cat. #IT-03), 0.25 µl bilateral injections of 1 µg/µl into the LC; orexin-SAP (Cat. #IT-20), 0.25 µl injection of 0.25 µg/µl into the TMN; 192-IgG-SAP (Cat. #IT-01), 3 µl injection of 2 µg/µl into the lateral ventricle. Small differences were observed in sleep architecture, but the data do not support the traditional hypothesis that these three areas of the brain are essential links in the control of wake levels.

Elimination of rat spinal substance P receptor bearing neurons dissociates cardiovascular and nocifensive responses to nicotinic agonists

Khan IM, Wart CV, Singletary EA, Stanislaus S, Deerinck T, Yaksh TL, Printz MP

Neuropharmacology 54(2):269-279, 2008.

Nocifensive behavior and cardiovascular responses due to nicotinic agonists may be sustained by substance P-positive primary afferents. Rats received 10-µl intrathecal injections of 10 µM SP-SAP (Cat. #IT-07); unconjugated saporin (Cat. #PR-01) was used as a control. Lesioned animals displayed reduced nocifensive response to nicotinic agonists. Tachycardia and pressor responses were enhanced upon administration of cytisine and epibatidine.

Respiratory plasticity in response to changes in oxygen supply and demand

Bavis RW, Powell FL, Bradford A, Hsia CCW, Peltonen JE, Soliz J, Zeis B, Fergusson ED, Fu Z, Gassmann M, Kim CB, Maurer J, McGuire M, Miller BM, O'Halloran KD, Paul RJ, Reid SG, Rusko HK, Tikkanen HO, Wilkinson KA

Integ and Comp Biol 47(4): 532-551, 2007.

This paper covers data presented at the First Annual Congress of Respiratory Biology. One of the subjects discussed is the use of SP-SAP (Cat. #IT-07) to elucidate the role of central chemoreceptors in the nucleus tractus solitarius during ventilatory acclimatization to hypoxia.

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