control-conjugates

Bugarith K, Dinh TT, Li AJ, Speth RC, Ritter S (2006) Featured Article: Basomedial hypothalamic injections of neuropeptide Y conjugated to saporin selectively disrupt hypothalamic controls of food intake. Targeting Trends 7(4)

Related Products: Anti-DBH-SAP (Cat. #IT-03), NPY-SAP (Cat. #IT-28), Saporin (Cat. #PR-01), Blank-SAP (Cat. #IT-21)

Read the featured article in Targeting Trends.

See Also:

• Bugarith K et al. Basomedial hypothalamic injections of neuropeptide Y conjugated to saporin selectively disrupt hypothalamic controls of food intake. Endocrinology 146(3):1179-1191, 2005.

Nattie E, Li A (2006) Neurokinin-1 receptor expressing neurons in the ventral medulla are essential for normal central and peripheral chemoreception in the conscious rat. J Appl Physiol 101(6):1596-1606. doi: 10.1152/japplphysiol.00347.2006

Summary: All known chemoreceptor sites in the mammalian brainstem are rich in the neurokinin-1 receptor (NK1r). The authors ask if these cells scattered throughout the ventral medulla are involved in central and peripheral chemoreception. Rats received 250-280 ng of SSP-SAP (Cat. #IT-11) into the cisterna magna, mouse IgG-SAP (Cat. #IT-18) was used as a control. The results indicate that NK1r neurons in the ventral medulla are involved in both central and peripheral chemoreception, during both waking and sleep states.

Related Products: SSP-SAP (Cat. #IT-11), Mouse IgG-SAP (Cat. #IT-18)

Parikh V, Sarter M (2006) Cortical choline transporter function measured in vivo using choline-sensitive microelectrodes: clearance of endogenous and exogenous choline and effects of removal of cholinergic terminals. J Neurochem 97(2):488-503. doi: 10.1111/j.1471-4159.2006.03766.x

Summary: A major projection of brain attention systems passes through the cholinergic portion of the cortical mantle. The authors investigated the role of high-affinity choline transporters (CHT) in the clearance of exogenous choline, as well as choline from newly released acetylcholine. 0.085 µg of 192-IgG-SAP (Cat. #IT-01) was injected into each hemisphere of the basal forebrain of rats (mouse IgG-SAP, Cat. #IT-18, was used as a control). The results demonstrate that no matter the source, increases in choline concentrations are cleared by CHT’s.

Related Products: 192-IgG-SAP (Cat. #IT-01), Mouse IgG-SAP (Cat. #IT-18)

Foehr ED, Lorente G, Kuo J, Ram R, Nikolich K, Urfer R (2006) Targeting of the receptor protein tyrosine phosphatase beta with a monoclonal antibody delays tumor growth in a glioblastoma model. Cancer Res 66(4):2271-2278. doi: 10.1158/0008-5472.CAN-05-1221

Summary: The receptor protein tyrosine phosphatase ß (RPTPß) is overexpressed in astrocytomas, and is a potential target for tumor therapy. After testing antibodies against an extracellular domain of RPTPß in vitro with Mab-ZAP (Cat. #IT-04), two custom conjugates, 7E4B11-SAP and 7A9B5-SAP, were created by Advanced Targeting Systems. The authors tested the custom conjugates, using anti-DAT-SAP (Cat. #IT-25) as a positive control, and mouse IgG-SAP (Cat. #IT-18) as a negative control. The 7E4B11-SAP conjugate displayed significant antitumor activity in mice engrafted with U87 glioma cells.

Related Products: Mab-ZAP (Cat. #IT-04), Anti-DAT-SAP (Cat. #IT-25), Mouse IgG-SAP (Cat. #IT-18), Custom Conjugates

Li A, Nattie E (2006) Catecholamine neurones in rats modulate sleep, breathing, central chemoreception and breathing variability. J Physiol 570(Pt 2):385-396. doi: 10.1113/jphysiol.2005.099325

Summary: Brainstem catecholamine (CA) neurons are thought to modulate the processing of sensory information and participate in the control of breathing. Using a 5 µg injection of anti-DBH-SAP (Cat. #IT-03), or a control injection of mouse-IgG-SAP (Cat. #IT-18) into the fourth ventricle, the authors investigated breathing frequency and wakefulness. The results suggest that CA neurons promote wakefulness, participate in central respiratory chemoreception, stimulate breathing frequency, and minimize breathing variability during REM sleep.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)

Q: We just completed surgeries where we implanted third ventricular cannulas and temporary bilatera cannulas directed into the nucleus tractus solitarius in the brainstem of animals. We injected either the Blank-SAP control toxin (Cat. #IT-21) or the experimental material Oxytocin-SAP into the bilateral NTS cannulae over a 30-second period. However, within the next week — two weeks post-surgery, we lost 13 of the 19 animals treated; they appeared not to be able to groom properly and lost over 20% of their body weight. This was apparent in both the Blank-SAP and the Oxytocin-SAP groups. We gave a dose of 40 ng/300 nl for each of the reagents. This dose was determined based on a published article using another of ATS’s targeted toxins. I’m very surprised by my results. Can you offer any explanation/advice?

A: This is a particularly disturbing result; it appears that a dose was chosen by comparison to one used with another targeted toxin. Although this can be a good approximating tool to begin a dose-ranging study, it usually doesn’t take into account the tissue, system, target molecule — so many parameters that are important to determining the proper dosage. The literature is quite extensive on targeted toxins, and so there may be a comparable starting dose that has been published. Let’s use, for example, 4 mg. Reduce that amount by 20% quantities (4, 3.2, 2.4) and test in a small number of animals to determine a value that is safe and effective. If no trouble is seen at the highest dose, and the effect is minimal, that would indicate a higher dose may be acceptable. You can then test doses in 20% increased increments (4.8, 5.6, 6.4). The effects you see in your animals should only be reflective of the particular cell type you are eliminating. In the case of control reagents, such as Blank-SAP, no cell type is being targeted, so if you are seeing any kind of result, then you are certainly over-dosing.

Q: Is there some kind of formula that one can use that will help determine a starting point for establishing a range of doses to test in animals prior to initiating a study? For example, if the targeted toxin is administered intravenously, does it take more or less material than when administered directly into tissue?

A: Start with a few animals and do dose-ranging as discussed in the previous question. The various modes of application are really too wide to discuss in any detail here, but I, a biochemist by training, always like the approach of thinking about what sort of concentration will be needed to have a cytotoxic effect. Generally, these molecules have an ED50 in the nanomolar to picomolar range. Obviously if you inject systemically, the material from the first becomes greatly diluted, relative to an injection directly into tissue, and so you’ll need a lot more. If you inject directly into tissue the local concentration can be quite high.

See: Targeted Toxins, Control Conjugates

Bugarith K, Dinh TT, Li AJ, Speth RC, Ritter S (2005) Basomedial hypothalamic injections of neuropeptide Y conjugated to saporin selectively disrupt hypothalamic controls of food intake. Endocrinology 146(3):1179-1191. doi: 10.1210/en.2004-1166

Summary: The authors examined the effect of 48 ng injections of NPY-SAP (Cat. #IT-28) into the basomedial hypothalamus (BMH) on glucoprivic feeding in rats. While there was no evidence of retrograde transport, the lesions inhibited responses to intracerebroventricular leptin and ghrelin. Neither the feeding nor the hyperglycemic response to 2-deoxy-D-glucose was affected by the lesion, indicating that these hindbrain processes do not utilize neurons in the BMH. This work also describes dosing and injection parameter studies for the use of NPY-SAP.

Related Products: NPY-SAP (Cat. #IT-28), Blank-SAP (Cat. #IT-21)

Read the featured article in Targeting Trends.

Buffo A, Carulli D, Rossi F, Strata P (2003) Extrinsic regulation of injury/growth-related gene expression in the inferior olive of the adult rat. Eur J Neurosci 18(8):2146-2158. doi: 10.1046/j.1460-9568.2003.02940.x

Summary: Inferior olive (IO) cells of the CNS have the ability to regenerate axons after injury, even when the injury is close to the terminal field. After administration of 2.2 µg of 192-Saporin (Cat. #IT-01) and a control immunotoxin (mouse IgG-SAP, Cat #IT-18) to each ventricle in rats, two subsets of IO cells were discovered. Each subset responded differently to injury indicating that multiple mechanisms are responsible for their intrinsic regenerative potential.

Related Products: 192-IgG-SAP (Cat. #IT-01), Mouse IgG-SAP (Cat. #IT-18)

Kanold PO, Kara P, Reid RC, Shatz CJ (2003) Role of subplate neurons in functional maturation of visual cortical columns. Science 301(5632):521-525. doi: 10.1126/science.1084152

Summary: Subplate neurons play a role in the development of connections between the thalamus and cerebral cortex. The authors used 0.5-µl injections of 0.25-1.0 mg/ml of ME20.4-SAP (Cat. #IT-15) to eliminate p75 receptor-positive neurons in the subplate of cats to investigate whether these neurons are involved in the organization and maturation of the visual cortex. This study also uses mouse IgG-saporin (Cat. #IT-18) as a control.

Related Products: ME20.4-SAP (Cat. #IT-15), Mouse IgG-SAP (Cat. #IT-18)

Read the featured article in Targeting Trends.

Lappi DA (2002) Featured Article: Control conjugates: The perfect companion for targeted toxins. Targeting Trends 3(1)

Related Products: Rat IgG-SAP (Cat. #IT-17), Mouse IgG-SAP (Cat. #IT-18), Goat IgG-SAP (Cat. #IT-19), Blank-SAP (Cat. #IT-21)

Read the featured article in Targeting Trends.