Mouse Adiponectin RIA

Adiponectin is a new member of an ever increasing family of adipocytokines and is also referred to as ACRP-30 (adipocyte compliment related protein-30), Adipo-Q, and APM-1 (adipose tissue most abundant gene transcript-1). Adiponectin is a predominant secretory protein from adipose tissue and circulates in micro-gram/ml quantities and has a structural homology with the type VIII collagen and hibernation specific protein, C1q.

In contrast to the majority of secreted proteins from adipose tissue, which are elevated in obesity, adiponectin appears to be either decreased or unaltered with degree of adiposity. More intriguingly, adiponectin seems to ameliorate the obesity related risk factors unlike other adipose tissue secretory proteins which contribute toward the health risks associated with obesity. Adiponectin also has an insulin sensitizing effect making it an excellent candidate in drug development for obesity and diabetes. Circulating adiponectin levels seem to be an excellent biochemical marker for improved insulin resistance in obese and diabetic states. This kit is for research purposes only.

II. PRINCIPLES OF PROCEDURE

In radioimmunoassay, a fixed concentration of labeled tracer antigen is incubated with a constant dilution of antiserum such that the concentration of antigen binding sites on the antibody is limited, for example, only 50% of the total tracer concentration may be bound by antibody. If unlabeled antigen is added to this system, there is competition between labeled tracer and unlabeled antigen for the limited and constant number of binding sites on the antibody. Thus, the amount of tracer bound to antibody will decrease as the concentration of unlabeled antigen increases. This can be measured after separating antibody-bound from free tracer and counting one or the other, or both fractions. A calibration or standard curve is set up with increasing concentrations of standard unlabeled antigen and from this curve the amount of antigen in unknown samples can be calculated. Thus, the four basic necessities for a radioimmunoassay system are: a specific antiserum to the antigen to be measured, the availability of a radioactive labeled form of the antigen, a method whereby antibody-bound tracer can be separated from the unbound tracer, and finally, an instrument to count radioactivity.

 

The LINCO Research, Inc. Adiponectin RIA assay utilizes 125I-labeled Murine Adiponectin and a Multispecies Adiponectin Rabbit antiserum to determine the level of Adiponectin in serum, plasma or tissue culture media by the double antibody/PEG technique. The Adiponectin Standards are prepared using recombinant Mouse Adiponectin and can be used to determine the circulating levels of adiponectin in mouse or rat serum/plasma samples.

III. REAGENTS SUPPLIED

Each kit is sufficient to run 125 tubes and contains the following reagents.

A. 10X Assay Buffer

Final concentration upon dilution is 10.0 mM Phosphate Buffer, pH 7.6 containing 0.08% Sodium Azide, 0.1 % RIA Grade BSA

Quantity: 50 ml/vial

Preparation: Dilute the contents of the vial with 450 ml distilled or deionized water

B. Adiponectin Antibody

Rabbit anti-Adiponectin Antibody

Quantity: 13 ml/vial

Preparation: Ready to use

C. 125I-Adiponectin

125I-Adiponectin Label (specific activity 67.7 µCi/µg)

Lyophilized for stability. Freshly iodinated label contains <3 µCi, (<111 kBq) calibrated to the 1st Monday of each month.

Quantity: 13.5 ml/vial upon hydration

Preparation: Contents Lyophilized. Hydrate with 13.5 ml of 1X Assay Buffer. Allow to sit at room temperature for 30 minutes, with occasional gentle mixing.

NOTE: You will observe that the Adiponectin tracer displays lower B0 binding as it approaches its expiration date. This does not alter the performance of the kit since the Quality Control values remain within expected ranges throughout the tracer shelf life.

D. Murine Adiponectin Standards

Purified Recombinant Adiponectin, 100 ng/ml

Lyophilized for stability.

Quantity: 1 ml upon hydration

Preparation: Contents Lyophilized. Hydrate with 1 ml distilled or deionized water.

E. Quality Controls 1& 2

Purified Recombinant Adiponectin

Lyophilized for stability

Quantity: 1 ml/vial upon hydration

Preparation: Contents Lyophilized. Hydrate with 1 ml distilled or deionized water.

F. Rabbit Carrier

30% Normal Rabbit Serum

Quantity: 2 ml/vial

Ready to use

G. Precipitating Reagent

Goat anti-Rabbit IgG Serum, 3% PEG and 0.05% Triton X-100 in 0.05M Phosphosaline, 0.025M EDTA,

0.08% Sodium Azide

Quantity: 130 ml/vial

Preparation: Ready to use; chill to 4°C

IV. STORAGE AND STABILITY

 

Prior to use, refrigerate all reagents between 2 and 8°C for short-term storage. For prolonged storage (>2 weeks), freeze at £ -20°C. Once the standards have been reconstituted, unused portions should be stored at £ -20°C. Avoid multiple freeze/thaw cycles. Refer to date on bottle for expiration when stored at £ -20°C. Do not mix reagents from different kits unless they have the same lot number.

V. REAGENT PRECAUTIONS

A. Radioactive Materials

This radioactive material may be received, acquired, possessed and used only by research personnel or clinical laboratories for in vitro research tests not involving internal or external administration of the material, or the radiation therefrom, to human beings or animals. Its receipt, acquisition, possession, use and transfer are subject to the regulations of the U. S. Nuclear Regulatory Commission (NRC) or of a State with which the Commission has entered into an agreement for the exercise of regulatory authority.

The following are suggested general rules for the safe use of radioactive material. The customer’s Radiation Safety Officer is ultimately responsible for the safe handling and use of radioactive material.

1. Wear appropriate personal devices at all times while in areas where radioactive materials are used or stored.

2. Wear laboratory coats, disposable gloves, and other protective clothing at all times.

3. Monitor hands, shoes, and clothing and immediate area surrounding the workstation for contamination after each procedure and before leaving the area.

4. Do not eat, drink, or smoke in any area where radioactive materials are stored or used.

5. Never pipette radioactive material by mouth.

6. Dispose of radioactive waste in accordance with NRC rules and regulations.

7. Avoid contaminating objects such as telephones, light switches, doorknobs, etc.

8. Use absorbent pads for containing and easily disposing of small amounts of contamination.

9. Wipe up all spills immediately and thoroughly and dispose of the contaminated materials as radioactive waste. Inform Radiation Safety Officer.

B. Sodium Azide

Sodium Azide has been added to all reagents as a preservative at a concentration of 0.08%. Although it is at a minimum concentration, sodium azide may react with lead and copper plumbing to form highly explosive metal azides. On disposal, flush with a large volume of water to prevent azide build up.

VI. MATERIALS REQUIRED BUT NOT PROVIDED

1. Borosilicate glass tubes, 12 x 75 mm. (NOTE: Polypropylene or polystyrene tubes may be used if the investigator finds that the pellet formation is acceptably stable in their system.)

2. Borosilicate glass tubes, 12 x 100 mm, or equivalent for sample dilutions

3. 10, 20, and 100 µl pipettes with disposable tips

4. 100 µl & 1.0 ml repeating dispenser

5. Refrigerated swing bucket centrifuge capable of developing 2,000 - 3,000 xg. (Use of fixed-angle buckets are not recommended.)

6. Absorbent paper

7. Vortex mixer

8. Refrigerator

9. Gamma Counter

VII. SPECIMEN COLLECTION AND STORAGE

1. Sample volumes of at least 5 µl of rat or mouse serum/plasma can be used (see Sample Preparation, Section VIII. B). Sample volumes of 50 - 100 ul of Tissue Culture Media may also be used.

2. Specimens can be stored at 2-8°C if they will be tested within 24 hours of collection. For longer storage, specimens should be stored at £ -20°C. Avoid multiple freeze/thaw cycles.

3. Avoid using samples with gross hemolysis or lipemia.

VIII. ASSAY PROCEDURE

For optimal results, accurate pipetting and adherence to the protocol are recommended.

A. Dilute the 10X Assay Buffer with 450 ml distilled or deionized water to prepare working concentration of 1X Assay Buffer.

B. Mouse Adiponectin Standard Preparation

1. Use care in opening the lyophilized Standard vial. Using an Eppendorff pipette, reconstitute the Mouse Adiponectin Standard with 1 ml distilled or deionized water into the glass vial to give a 100 ng concentration of Standard. Mix well.

Label seven glass tubes 50, 25, 12.5, 6.25, 3.125, 1.56, 0.78 ng/ml. Add 0.5 ml Assay Buffer to each of the seven tubes. Prepare serial dilutions by adding 0.5 ml of the 100 ng/ml reconstituted standard to the 50 ng/ml tube, mix well and transfer 0.5 ml of the 50 ng/ml Standard to the 25 ng/ml tube, mix well and transfer 0.5 ml of the 25 ng/ml Standard to the 12.5 ng/ml tube, mix well and transfer 0.5 ml of the 12.5 ng/ml Standard to the 6.25 ng/ml tube, mix well and transfer 0.5 ml of the 6.25 ng/ml Standard to the 3.125 tube, mix well and transfer 0.5 ml of the 3.125 ng/ml Standard to the 1.56 ng/ml tube, mix well and transfer 0.5 ml of the 1.56 ng/ml Standard to the 0.78 ng/ml tube and mix well.

Note: Do not use a Repeater pipette. Change tip for every dilution. Wet tip with Standard before dispensing. Unused portions of standard should be stored at £ -20°C. Avoid multiple freeze/thaw cycles.