Antibiotic-acrylic bone cement composites. Studies of gentamicin and Palacos

Palacos bone cement with and without contained gentamicin was tested for antibacterial efficacy using a rabbit model of a knee hemiarthroplasty and a challenge with intra-articular Escherichia coli. The gentamicin-containing cement prevented infection from challenge with Escherichia coli and protected against inadvertent operative infection as well. Antibiotic concentrations in synovial fluid and urine remained in the therapeutic range for three days, whereas levels in serum were always quite low. Eight per cent of the gentamicin had leached out of the bone cement by eight days, most of it during the first day. Thereafter, extremely small amounts of gentamicin left the cement on a daily basis. The amount of antibiotic leaching out in vitro was proportional to the surface area of the cement. More eluted into serum than into saline.

Cefazolin concentrations in bone and synovial fluid

A single intravenous dose of one gram of cefazolin was administered prophylactically to forty-eight patients undergoing total joint replacement. The serum half-life of the antibiotic was 1.8 hours, the same value found in normal volunteers. The mean concentration in bone during surgery was 5.7 micrograms per gram of bone. The mean concentration in synovial fluid during surgery was 24.4 micrograms per milliliter of fluid.

Plasma cell content of main and accessory lacrimal glands and conjunctiva

The size, weight, and plasma cell content of main and accessory lacrimal glands were examined and compared to the number of plasma cells in the conjunctiva. There were from four to 35 accessory lacrimal glands in the upper conjunctiva and a rare accessory gland in the lower conjunctiva. The total accessory gland mass was approximately one tenth of the lacrimal gland mass although the number of plasma cells was approximately 1/20 of the mass. The number of plasma-cells in the lacrimal gland was estimated to be 3,200,000; in the conjunctiva, 2,100,000; and for the accessory glands, 180,000. Because of the many plasma cells in the relatively inaccessible lacrimal gland, cells of the lymphatic series may home to the lacrimal gland by non-antigenic mechanisms.

ABO Blood groups and corneal transplantation

A study of 150 corneal donor-recipient grafts, examined for ABO type, revealed that 25% of the grafts were from corneas from incompatible donors. Recipients with histocompatible sensitization exposures such as prior corneal transplant, one or more pregnancies, or one or more blood transfusions were no more likely to experience graft failure if the graft were from an ABO incompatible donor than from a compatible donor. Of 13 graft failures (8%), three of the failed grafts were from AB donors, a significant result. No detrimental effect of transplanting across the ABO barrier could be proven with assurance for any parameter.