Investigation of the anti-complement agents, FUT-175 and K76COOH, in discordant xenotransplantation

Abstract: We examined whether hyperacute rejection (HAR) of a discordant xenograft in a nonhuman primate model could be inhibited by the anticomplement agents, FUT-175 (FUT) and K76COOH (K76). The inhibitory effect of FUT and K76 on baboon sera was studied in vitro by i) complement-mediated hemolysis of sheep erythrocytes (by measuring serum CH50) and ii) cytotoxicity to cultured pig kidney (PK15) cells. The in vivo administration of FUT (at 0.2–25 mg/kg/h i.v. continuously) and K76 (50 mg/kg i.v. bolus) allowed evaluation of the serum levels of these drugs. Both FUT and K76 inhibited serum CH50 in a concentration-dependent manner. An enhanced effect was obtained by combining K76 with FUT therapy. High concentrations of FUT (>10^-4 M) and K76 (>10³ μxg/ml) were necessary to suppress serum CH50 to <5% of the normal level. However, PK15 cytotoxicity remained at >50% in the presence of i) 10^-4 M of FUT, ii) 10³ μg/ml of K76, and iii) 10^-6 M of FUT + 10³ μg/ml of K76. Pig heart transplantation (HTX) was performed in two baboons receiving FUT (1 mg/kg/h i.v. continuously) and K76 (at 200 mg/kg ×1 or 400 mg/kg + 200 mg/kg × 2 i.v, respectively). Cytotoxicity of the serum to PK15 cells at the time of HTX showed 39% and 1% cell death, respectively, in these two baboons, and the CH50 level was 1% (of control level) and 0%, respectively. Graft survival was 4.5 hours and 10 hours (with death of the baboon), respectively (compared with a mean of 29 minutes in control experiments). Both excised grafts showed typical features of hyperacute rejection. Immunopathological studies revealed deposition of C1q, C3d, C6, properdin, and Factor B, demonstrating that complement activation was not fully inhibited by FUT and K76. We conclude that i) FUT and K76 are indeed potent complement inhibitors, ii) the dosages of FUT and K76 necessary to suppress complement-mediated injury cannot be extrapolated from previously reported data obtained from serum CH50 levels, and iii) higher (possibly toxic) dosages will be required to inhibit complement activation completely. It seems unlikely that HAR will be prevented by these drugs alone, although they may be beneficial when combined with other forms of therapy.     

Simultaneous M-mode echoesophagram and manometry in the sheep esophagus

We report the simultaneous measurement of esophageal wall layer thickness and intraluminal pressure in the sheep esophagus using a miniature suction device incorporating a high-frequency ultrasound transducer and a manometry system. Transnasal placement of the device into the distal esophagus of a conscious sheep allowed observation of 133 swallowing events during three trials, each lasting from 45 to 60 minutes. In a fourth trial, 11 sequential dry and 23 sequential wet swallows were compared. Maximum manometric pressure, esophageal wall layer thickness, and duration of contraction were measured. All swallowing events produced simultaneous increases in intraluminal pressure and esophageal wall thickness. Mean maximal pressures were lower for dry swallows (18 ± 2.1 mm Hg) than wet swallows (22 ± 3.0 mm Hg) (p < .01). Thickness of the inner (circular) muscle layer increased above baseline by 124% for dry swallows and 161% for wet swallows (p < .01). We conclude that thickening of the esophageal inner (circular) muscle layer may be important in the generation of intraluminal esophageal pressure in the sheep esophagus. (Gastrointest Endosc 1995;41:582-6.)     

Clinical experiences with a new membrane oxygenator with low priming volume (D702 MASTER FLO 51), studies during pulsatile and constant flow perfusion

The newly developed oxygenator "D702" is a compact hollow fiber membrane oxygenator with a priming volume of 170 ml. The maximum flow allowance is 4 liters per/minute. We used this oxygenator in 16 patients (11 infants and children, and 5 adults) undergoing various open heart surgery, and function of this oxygenator was studied. Pulsatile cardiopulmonary bypass was performed in 8 patients and nonpulsatile constant flow perfusion was employed in the remaining 8 patients. Our clinical experience showed excellent maintenance of PaO2 and PaCO2 during both pulsatile and constant flow bypasses. A low pressure drop was encountered across the membrane oxygenator, and therefore, this oxygenator is applicable for pulsatile cardiopulmonary bypass. The D702 is a very useful and applicable for a wide range of patients from infants to adults with a small body structure.     

Interleukin 2 (IL2) is assigned to human chromosome 4

The human gene for interleukin 2 (IL2)was assigned to chromosome 4 using human-mouse somatic cell hybrids and Southern filter hybridization of cell hybrid DNA. To identify IL2,a recombinant DNA probe (pIL2-50A) was used which contained a human interleukin 2 cDNA insert which hybridized to a 3.5-kb fragment in human DNA when cleaved with the restriction enzyme EcoRL.     

Focal hyperplasia of intracytoplasmic filaments in the canine parathyroid gland treated with nalidixic acid

Focal hyperplasia of intracytoplasmic filaments of 100A in diameter was observed within chief cells of the parathyroid gland in dogs treated with nalidixic acid. The structure, as a rule, was located in the neighborhood of the nucleus and no other cell organelles were detected within it. Its size had a wide spectrum from a small part of the cytoplasm to as large as half a cell. Golgi apparatus and rough endoplasmic reticulum in the involved cells had a tendency to atrophy. These cells occasionally contained less secretory granules. Lipid droplets are diffusely increased. The pathogenesis and significance of the present intracytoplasmic filaments remain to be determined. However, as lipid deposition, atrophy of Golgi apparatus, poorly developed rough endoplasmic reticulum occur in a hypofunctional or degenerative state, it might be possible that filamentous hyperplasia is closely associated with that state.