Transepithelial electrical resistance (TEER), also referred as the transepithelial resistance (TER) is used to monitor cellular health. TEER is comprised of measurements of the transcellular pathway (i.e., resistance due to an individual cell) and paracellular pathway (i.e., resistance due to the formation of the cellular junctions). TEER is commonly used to monitor cellular confluence. TEER values can indicate changes in the cellular monolayer permeability, showing the monolayer barrier function of cells such as, endothelial (brain microvessel) and epithelial (alveolar, kidney, and intestinal) cells. High TEER values generally reflect tighter cellular monolayers or cellular junctions (Lewis 1996, Matter and Balda 2003, Denker and Sabath 2011). A few major benefits of WPI TEER measurement systems are described below. The TEER values (electrophysiological analysis) can be combined with other analysis methods to further understand a biological phenomenon. For example, a decrease in the TEER value can indicate increased monolayer permeability which can be further confirmed by an assay using a tracer molecule (fluorescein-dextran).

Jonas de Jesus, from WPI Brasil visit the winner of a contest to name a mascot for the Zebrafish Network. Jonas presented the winner with a surgical kit for zebrafish research.

One's imagination is the limit with practical uses of WPI's Liquid Wavelength Capillary Cells(LWCC), also referred to in the fiber optic spectroscopy community as a Long Pathlength Flow Cell. This fiber optic sampling accessory for absorbance measurements combines increased optical pathlengths with small sample volumes making them ideal for water analysis such as CDOM.

When you need to quickly take minimally invasive, small samples, the biopsy punch is an easy choice. The biopsy punch is a hand held, pencil-shaped instrument with a slender, pencil-like body. It is lightweight with a hollow, circular, stainless steel, cutting tip.

When you are selecting surgical instruments for a procedure, here are a few key points to consider

• What procedure are you performing? Published research papers usually indicate which instruments other researchers have used for similar procedures. The correct surgical instrument for a particular procedure makes a difference on the outcome of that technique.
• What is the size of your subject? An instrument that is perfect for a 200­–300 g rat (about 22–25 cm long) may not be the best choice for a neo-natal mouse of about 15 g (about 1–2.5 cm long).
• How often will the instrument be used? If you perform more than 100 cuts per day, a pair of titanium scissors or a pair of scissors with tungsten carbide inserts would be worth considering. They stay sharp longer.

In this video you'll see how to replace the gasket in a >Nanoliter2010. 

NOTE: NANOLITER2010 was replaced by the NANOLITER2020

The use of fluorescent probes in cell physiology has emerged as indispensable tool in the analysis of cell functioning over recent years. The physics underlying fluorescence is illustrated by the electronic-state diagram (so-called Jablonski diagram, see Fig. 1), showing the three-stage process to create the fluorescent signal (Excitation - Excited/State Lifetime - Fluorescence Emission) in a fluorophore/indicator and simplified described below.

Absorption of light correlates to the energy of a photon that is taken-up by electrons of the substance atom. The electromagnetic energy is transformed into internal energy of the absorbent substance. The absorbance of a substance quantifies how much of the incident light is absorbed by it (instead of being reflected or refracted). Precise measurements of the absorbance at many wavelengths allow the identification of a substance via absorption spectroscopy, where a sample is illuminated from one side, and the intensity of the light that exits from the sample in every direction is measured (see Fig. 1). A few examples of absorption are ultraviolet–visible (UV-Vis) spectroscopy or infrared (IR) spectroscopy.

Absorption of light correlates to the energy of a photon that is taken-up by electrons of the substance atom. The electromagnetic energy is transformed into internal energy of the absorbent substance. The absorbance of a substance quantifies how much of the incident light is absorbed by it (instead of being reflected or refracted). Precise measurements of the absorbance at many wavelengths allow the identification of a substance via absorption spectroscopy, where a sample is illuminated from one side, and the intensity of the light that exits from the sample in every direction is measured (see Fig. 1). A few examples of absorption are ultraviolet–visible (UV-Vis) spectroscopy or infrared (IR) spectroscopy.

World Precision Instruments was selected to receive the FVMA (Florida Veterinary Medical Association) Industry Award for 2017.

The type of pump you choose for your fluid handling will largely depend on your laboratory application. In this article, we will compare the popular pump types.

Application kits are specially designed for eye research for injecting retinal pigment epithelium (RPE) and for intraocular (IO) injections. In addition, these kits may be used for brain injection in mice. They need to be used with a NanoFil syringe and UMPIII to achieve accurate, repetitive and oil-free injection in the submicroliter range.

The proper care and handling of your valuable surgical instruments will improve their longevity and function. Choose a protocol appropriate for your environment from the cleaning techniques below. See the videos here.

First, let's consider volumes.

• A milliliter (mL) is one thousandth the volume of a liter (L) or 10^-3L
• A microliter (µL) is one thousandth the volume of a mL (10^-6L)
• A nanoliter (nL) is one thousandth the volume of a µL (10^-9L)
• A picoliter (pL) is one thousandth the volume of a nL (10^-12L)

This is graphically represented at the right. Notice that the mL is one trillion times larger than the picoliter. The table (right) shows that the side of a cube with a volume of 1mL is 1cm long. Likewise, the side of a cube with a volume of 1pL is 10µm long. Just for comparison, it shows that the diameter of a sphere with a volume of 1mL is 1.24cm, and the volume of a sphere with a volume of 1pL is 12.4µm.

It’s hard to imagine that surgery wasn’t always the prestigious profession it is today. But, in medieval Europe, physicians didn’t practice surgery, because such things were handled by lesser men… or even by women. Often, the local barber took care of minor surgeries. He would travel from town to town, and you could stop in to get a haircut and shave, and at the same time get a tooth pulled or have a minor surgery.

World Precision Instruments' PUL-1000 is a microprocessor controlled, four-stage, horizontal puller for making glass micropipettes or microelectrodes used in intracellular recording, microperfusion and microinjection. It offers programmable sequences of up to four steps with complete control over the heating, force, movement and cooling time. This allows graduated cycles for a variety of applications. PUL-1000 can produce pipettes with tip diameters from less than 0.1µm to 10+ µm.

Here are some frequently asked questions (FAQ) about TEER measurement using an EVOM2.

A calibrated BLPR2 on the LabTrax24T was used to record the results. This is a plot of both pumps on the #14 tubing at 50 RPM into a 22 gauge needle. The flow is estimated to be 9 ml/min at 50RPM.

A low-noise amplifier like the DAM50 is an excellent choice for EEG recording in rodents. WPI's amplifiers were engineered for the bio-medical researcher. While 20-30μV of noise is common in bio-amplifiers, WPI’s DAM series amplifiers generate 0.4μV RMS (root mean squared) at 0.1-100Hz. (That’s equal to about 2μV peak to peak.) This setup shows one way such recordings could be made. The RC1 electrode works well for rats, and the EP1 is more suitable for mouse cranial application.

What's the difference between cleaning, disinfecting and sterilizing? Let's take a look. This is the first in a series of four videos to discuss some best practices in caring for your surgical instrument investment.