SOP FOR ELECTRONIC VON FREY

1.0    PURPOSE

To design a Standard Operating Procedure that describes the procedure for operation and maintenance of Electronic Von Frey 38450.

2.0 SCOPE

This Standard Operating Procedure (SOP) is applicable for the operation, and maintenance of Electronic Von Frey 38450 for Pharmacology studies conducted at AHF.

3.0 RESPONSIBILITY

3.1 All personnel in the Pharmacology Department shall be responsible for the implementation and compliance with the SOP.

3.2 Head/Designees/Study Directors of the Pharmacology department shall be responsible to ensure the implementation and compliance with the SOP.

4.0 DISTRIBUTION

4.1 The quality assurance department is responsible to keep SOP ‘Master Copy’ approved through the Quality Manager.

4.2 The copy of ‘Control Copy’ of all SOPs are being distributed in the AHF department and placed near related Equipment/ Instrument as ‘Display Copy’.

4.3 DEFINITIONS

The e-VF 38450 is an instrument, designed to evaluate the nociception assay. A touch stimulator transducer is mounted on a perspex bar so routine procedures may be employed to examine and test the animal skin sensitivity. The completion of each test may be indicated either by the sudden release of the paw or by pressing the external foot pedal.

5.0 ABBREVIATIONS

5.1 SOP : Standard Operating Procedure

5.2 AHF :  Animal House Facility

5.3 PPEs : Personal Protective Equipment

5.4 e-VF : Electronic Von Frey

5.5 PNL : Partial Sciatic Nerve Ligation

5.6 SNL : Spinal Nerve Ligation

5.7 CCI : Chronic Constricted Injury

6.0  PROCEDURE

6.1 INTRODUCTION

The most commonly used Von Frey filaments are productive in evaluating behavioral responses to neuropathic pain in preclinical and clinical research. To reduce the potential experimenter bias, automated instruments are being developed for behavioral assessment. In preclinical research, neuropathic pain models of nerve injury with varied etiology like partial sciatic nerve ligation (PNL), chronic constricted injury (CCI), and spinal nerve ligation (SNL) are employed to screen the analgesic drugs to treat symptoms like allodynia and hyperalgesia.

6.2 PRINCIPLE

Von Frey filaments rely on the principle that an elastic column, in compression, will buckle elastically at a specific force, dependent on the material's length, diameter, and modulus. Once buckled, the force imparted by the column is fairly constant, irrespective of the degree of buckling. The filaments may therefore be used to provide a range of forces to the skin of a test subject, in order to find the force at which the subject reacts because the sensation is painful. This type of test is called a mechanical nociceptive threshold test.

6.3 INSTRUMENT DESCRIPTION

6.3.1      ELECTRONIC UNIT

Figure 1: Setup of Electronic Unit

6.3.1.1 The electronic unit is battery operated and its internal rechargeable battery is charged automatically when external power is supplied to its miniature USB ‘B’ socket, either from a PC or from a suitable USB power adapter.

6.3.1.2 The three buttons below the display are soft buttons whose function changes at different stages of the e-VF program.

6.3.1.3 A relevant feature of the e-VF electronics is the Ratemeter which provides a visual cue to ensure that the desired force is applied at a consistent rate.

6.3.1.4 When the e-VF is switched OFF, it goes into a standby mode in which it takes almost no current from the battery although it still updates its internal calendar clock.

6.3.1.5 Prior to any measurements, e-VF automatically balances out any offsets using its auto-zero function and it stores the results of several hundred tests, which can be transferred to a PC when convenient.

6.3.2                      TOUCH STIMULATOR TRANSDUCER

Figure 2: Touch Stimulator Transducer

6.3.2.1 The Touch Stimulator Transducer incorporates a probe (filament) to stimulate the animal paw at a user-controlled application of force rate.

6.3.2.2 The glass prism is very useful for an easy location of the aimed stimulation area. As each e-VF transducer has a built-in identification chip, e-VF is able to interrogate each transducer and adjust its own internal specification to match that of the transducer.

6.3.3                      THE OPTIONAL BASE PLATFORM / PERFORATED SHEET ASSEMBLY

Figure 3: Optional Base/Platform 38450-278

                   The optional base assembly 37450- 278 is provided to ease the measurement on the plantar surface. A Perforated Metal Sheet (37450- 005), inserted into a consistent frame, is held in place by its own weight on the top of four supporting columns, over a metal base, dimensioned 90(w) x 38.5(d) x 3.5(h) cm, made of enameled aluminum.

Figure 4: Optional Enclosure

                   It consists of six separate lids making it easier to deposit/remove the rats individually shown in figure 4. The cage dimensions are 17x69x14cm. The enclosure is duly positioned on the framed perforated sheet by the spacers provided.

6.4   OPERATIONS

6.4.1 TURNING ON THE E-VF

The e-VF shall be turned ON, by pressing the ON/OFF button.

6.4.2 MENU OPERATION

E-VF shall be operated via a number of menus by pressing the three soft buttons, F1, F2, and F3 under the display.

6.4.3 MAIN MENU

This is the first menu that shall appear when eVF ON and this menu helps to choose the options relating to measurements and transferring collected data to the PC however the “Configure” menu allows the user to adjust a number of parameters to suit particular measurement requirements.

Figure 5: Main Menu

6.4.4 MEASURE MENU

              This menu consists of the following parameters and the display is shown in Figures 6 & 7. After a few seconds, e-VF completes an Autozero procedure and the following screen shall be displayed.  

                 

                 Figure 6: Measure Menu Screen                                              Figure 7: Screen After Autozero

                   This is the initial screen of the measure menu which consists of the following:

6.4.4.1 MEASURE PEAK FORCE

By pressing this option, the caption ‘EXIT’ and ‘TEST’ shall appear along with the current date and time When ‘TEST’ is pressed, a caption shall appear, intimating that no force be applied to the transducer during the autozero procedure, after which the following screen shall be displayed and the user shall start the test.

 

      Figure 5: Measure Menu Screens

6.4.4.2   VIEW ACQUIRED DATA

By selecting this from the measure menu the total number of stored measurements shall be displayed, and then the following screen will appear, with data related to the last measurement.
                                          

          Figure 6: Data Display Screen

6.4.4.3 TRANSFER DATA TO PC

The e-VF shall be connected to the PC via the USB cable supplied and that the PC is running the appropriate DCA software provided with the instrument.

6.4.5 MAINTENANCE

6.4.5.1 CLEANING THE PRISM

The prism shall be cleaned after each session with mild detergent.

6.4.5.2 LONG INACTIVITY

The instrument shall not be required any particular maintenance after long inactivity.

7.0 SAFETY PRECAUTION:

7.1 All PPEs like an apron, gloves, mask, head caps, and shoe cover should be worn before using the instrument.

7.2 Press Keys softly.

7.3 Clean the equipment with a dry piece of robe or a lightly moistened one, do not use organic solutions.

7.4 Never use abrasive products or dissolvents.

7.5 Never pour water or liquids on the equipment.

7.6 Once you have finished using the equipment turn it off by using the main switch, clean, and check the equipment so that it is in optimal conditions when you use it again.

7.7 Do not position the unit so that it is difficult to operate the main disconnect device.

7.8 Electrical outlets in the cabinet are restricted to 5 amps maximum current.

7.9 Do not use any detachable power cord that is not adequately rated for the unit.

7.10 Do not attempt to open or perform any service work

7.11 Do not connect up human subjects

7.12 Do not spray any liquid on the connectors;

7.13 Keep inflammables far from the instruments.

8.0 REFERENCE

8.1 Reference

8.1.1 Instruction Manual Ugo Basile eVF Electronic Von Frey Cat No. 38450

                       

END OF THE DOCUMENT

 

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