"Between 1996 and 2001, our population of mice doubled," explains Robert J. Adams, DVM, associate professor in the Department of Comparative Medicine. "We also were expanding the quality of the mouse. We were pushing towards housing the mice in micro-isolators to protect their health."

The 54,000-gsf (38,000-nsf) facility follows a standard racetrack layout with an 8-foot-wide, 300-foot-long perimeter corridor with 7-foot-wide perpendicular suite corridors for the animal research space, all enclosed in a partial interstitial space.

Because of the large movement of material handling racks, the hallways are lined with aluminum wall bumpers on two levels, and the doorways are equipped with rolling doorframe protection.

The perpendicular corridors lead to two suites, each with five animal holding rooms and two 9-by-23-foot procedure rooms. Each suite is equipped with a hand wash sink, a shower, and an eyewash station. The procedure rooms all have a laminar flow, rear-exhausted countertop, gas and vacuum, and one procedure room in each suite has a biosafety cabinet. The facility also includes one small BSL-3 suite with just two animal holding rooms and one procedure room, for a total of 46 animal holding rooms and 18 procedure rooms, as well as some behavioral and imaging rooms within the suites.

Two HEPA-filtered air handlers are dedicated to the animal space, each supplying half of the facility. The air comes down to each rack and is directly exhausted to the outside. All of the air coming out of the public spaces and the offices in the rest of the building goes through a heat recovery wheel, but the air in the animal research facility does not. Outside every room are a temperature and humidity gauge, and a low-tech, low-cost gauge for monitoring negative and positive pressure: a ping pong ball that goes through the wall and ends up on whichever side has the lower pressure.

Built for Mice

The University was able to realize some cost savings in design features and building materials because it intends to house nothing but rodents at the facility. The walls, for example, are constructed of steel studs covered with ¼-inch epoxy-coated Hardie board over ¼-inch gypsum. Larger animals, such as monkeys, are more destructive and require concrete block walls, explains Adams. Larger animals could not be transferred to this site.

"This is the first time we have ever built a facility that is rodent only." says Adams. "Our intent is to keep it that way."

The floors in the cagewash facility are methylmethacralate (MMA), because it is seamless and extremely durable. But all the rest are made of Altro sheet flooring, which is rubberized to dampen noise and cushion the researchers' feet. The seams in the Altro sheets are welded together, which would have been risky with larger, more destructive animals, says Adams.

Another feature that was possible because this is a rodent-only facility is the absence of floor drains in the animal holding rooms. The only floor drain in each suite is located in a janitor's closet in the hall. Floor drains create a breeding ground for little flies, says Adams, but they are unavoidable in facilities which house larger animals that don't always keep their waste inside their cages. Drains also require the floors to be sloped. But with rodents, the animal room floors can be sealed and flat, making them easier to build and maintain. Flat floors also make it easier to maneuver the racks of cages, which are all on casters.

Each animal holding room is 16 x 23 feet and contains about 1,000 cages on single and double-sided racks separated by a five foot corridor. Each room is equipped with one Baker changing station and two systems of lighting—one white and one red.

"When the computer says it is nighttime, the only light you can get in an animal room is red light," says Adams. "The hallways go red, as well, to try to make sure we don't interfere with circadian rhythm. Just in case, there is red glass in the entry door."

Automation Cuts Labor Costs

A critical function of any animal facility is keeping the cages clean. Johns Hopkins has automated that operation so that two workers operating robots can accomplish what it used to require 12 workers to do manually.

Two indexing tunnel washers are fed by a pair of 25-foot-long conveyors on which pallets holding cages and water bottles are placed. The pallets are loaded and unloaded by robots. On the dirty side, the robots lift the cages four at a time and dump the soiled bedding into a disposal system that breaks it up and sends into the city sewer. The key to the material management system is the "fishbone rack," a specially designed rack that holds the cages and their covers, so named because the cage lids slide into diagonal slots configured like the bones of a fish. All of the cage parts for a 70-cage ventilated rack are held on one fishbone.

"We bring two fishbones into each room: one containing autoclaved cages and the other empty to receive the soiled cages," explains Adams. "The fishbone is transported to the soiled side of the cagewash area, where you lift a pallet up with the cages, put it on the conveyor, and push the button. If everything works well, the robot takes care of it. Then, you push the fishbone containing the wire bar lid and cage top through the rack washer."

The robots also refill the cages with bedding, and the water bottles are automatically filled. About 90 percent of the cages have their water piped in, obviating the need for bottles, but there are still around 4,000 water bottles in use at the facility.

"We only handle the cages once, and that is in the animal holding room," says Adams. "The cages and bottles are washed in the tunnel washer. The wire bar lids and the plastic lids remain on the fishbone cart, and they get passed through the rack washer. Bedding is automatically added to the cage. When it all comes back on the clean side, we put the pallet back on the fishbone and it goes through the autoclave."

Automation not only costs less, but it also takes over the dirtiest work from the employees, making it a more pleasant place to work, he says.

Lessons Learned

The University already is rethinking some of the features of this research space, and is designing its next one differently. A major problem is that the animal rooms are too small, says Adams. Technicians need at least six feet, not five, between the racks to maneuver their equipment.

"In our next facility that is being constructed right now, we are doing away with that center row of racks," says Adams.

Researchers also need proportionally more procedure rooms. The Broadway Research Building has one procedure room for every two-and-a-half animal holding rooms.

"One-to-one may be a more reasonable ratio," says Adams. "But for every procedure room you build, you pull out animal holding space. Somewhere there is a tradeoff."

In addition, each procedure room should be equipped with at least one biosafety cabinet, says Adams.

"Somewhere along the line, we pulled a biosafety cabinet out of one procedure room in each suite," explains Adams. "We insist that all animal use be done in a cabinet right now, because we still have conventional animals on campus. They are due to disappear (early in 2005), but until they are gone, we have to do everything in the hood.

"Once we get rid of the dirty animals and we show that we can keep things clean, we will start to let investigators use (the countertops) for something other than terminal procedures," says Adams.

The facility also lacks behavior rooms. It was designed with a core of rooms for behavior studies, but the current researchers are doing behavior studies on only a few animals at a time, so that configuration is inefficient.

Researchers discovered soon after moving in that they also do not have adequate lockable storage space for their belongings.

"That's something we overlooked," concedes Adams.

Adams also cautions against contracting with overseas vendors unless they have a consistent presence in the United States to handle questions and work out the bugs of a new system.

By Lisa Wesel

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