Free jejunal graft reconstruction after extensive head and neck surgery

Seven patients with benign and malignant head and neck lesions underwent reconstruction with free jejunal grafts using microvascular techniques. Benefits included preservation and maximal tongue function, acceptable cosmetic appearance and a short, one-stage reconstructive period.     

Toxoplasmosis in free-ranging chacma baboons (Papio ursinus) from the Kruger National Park

Serological evidence of toxoplasmosis was found in 11 of 94 (11·7% ) free-ranging chacma baboons from the Kruger National Park. 4 of these animals also showed typical cysts in the heart, brain, and skeletal muscles, without any accompanying inflammatory response.     

Partial deletion of chromosome 2 mimicking a phenotype of trisomy 18: Case report with autopsy

Clinical, cytogenetic, and autopsy findings are presented in the case of a liveborn female with multiple congenital anomalies mimicking trisomy 18 phenotype, but with partial deletion of the long arms of chromosome 2, region 2, bands 3 and 4.     

Immune Lysis of Liposomes and Erythrocyte Ghosts Loaded with Spin Label

It is shown that the paramagnetic resonance of spin labels offers a convenient technique for monitoring the complement-mediated immune lysis of erythrocyte ghosts, and sensitized phospholipid liposomes. The ghosts or liposomes are loaded with a concentrated solution of a water-soluble, membrane-impermeable spin label, so that there is a strong exchange broadening of the paramagnetic resonance signal due to labels enclosed within the liposomes or ghosts. Complement-mediated lysis releases the labels into a dilute solution, where a relatively sharp and intense paramagnetic resonance signal is detected.AN UNANTICIPATED RESULT IS ALSO REPORTED: this is the augmentation of release of spin label from loaded ghosts sensitized with egg albumin, in the presence of antibody against egg albumin, complement, and egg albumin in solution, over and above the release in the absence of egg albumin in solution. Comparison with complement fixation suggests that the augmentation of lysis is effected by crosslinking of immune complexes with the cell membrane.     

Membrane-controlled depletion of complement activity by spin-label-specific IgM

Complement depletion mediated by high molecular weight (IgM) rabbit antibodies specifically bound to spin-label lipid haptens dispersed in model membranes is controlled by various physical attributes of those membranes other than the total number of exposed determinants that they provide. Carrier lipids used at 32 degrees were (i) a "fluid" phosphatidylcholine (PC), (ii) a "solid" PC, and (iii) a cholesterol/PC mixture. The concentration of hapten in the plane of the membranes (two-dimensional concentration) was varied while the overall hapten molarity (three-dimensional concentration) was kept constant.Both specific binding and the efficiency of depletion by IgM are markedly enhanced by systematically decreasing the average distance between haptens (infinity --> 26 A). Heterogeneous distribution was found to be more favorable than a random homogeneous distribution of the same number of haptens in the same total quantity of lipids. IgM efficiency is also markedly increased by the inclusion of cholesterol in PC membranes, an effect thought to result from enhanced projection of the determinant from the surface of the membrane and hence increased accessibility to the antibody-binding site. Furthermore, the efficiency of IgM was increased by using haptens dispersed in fluid rather than in solid PC membranes.The results are consistent with the hypothesis that IgM molecules must be bound to a critical multiple of antigenic determinants at a membrane surface in order to induce complement-mediated attack and that subtle variation of the physical state of membrane antigens can be the crucial factor in determining the outcome of this type of efferent immune response.     

Demonstration by radionuclide imaging of possible vascular steal from a renal transplant.

Radionuclide studies in a renal-transplant patient with congestive heart failure suggested vascular steal from the renal allograft by a contralateral femoral arteriovenous fistula. These reliable, noninvasive diagnostic procedures have potential use in similar settings to evaluate allograft perfusion and function. Correction by removal of the fistula was demonstrated.     

Motion of steroid spin labels in membranes

Steroid spin labels have been found to undergo rapid and sometimes anisotropic rotational motion in membranes and phospholipid vesicle preparations. N-oxyl-4',4'-dimethyloxazolidine derivatives of 5alpha-androstan-3-one-17beta-ol, 5beta-androstan-3-one-17beta-ol, and 5alpha-androstan-3-one were prepared according to the procedure described by Keana. The paramagnetic five-membered ring is rigidly attached to the steroid nucleus at the 3-position, and thus the resonance spectrum of the nitroxide group reflects the motion of the entire steroid nucleus. This rapid motion, with rotational diffusion frequencies of the order of 10(7) to 10(8) second(-1) is considered to lend plausibility to models of membrane transport involving rotations and/or translations of carriers within the hydrophobic region of the membrane. The steroid spin labels also form a convenient class of probes for studying conformational changes in membranes, since (a) their resonance spectra often fall in the category of "intermediate immobilization," which is most sensitive to small changes, and (b) these labels are quite soluble in a wide variety of membranes.     

Complement Receptors and Cell Associated Complement Components

Membrane receptors for activated complement components are widely distributed amongst tissue cells of most mammalian species. Common amongst these are receptors for C3b which mediate many of the biological functions of C3. In addition, the genetic control of certain complement components is linked to the genes which code for the major histocompatibility complex. Many of these components are also present on cell surfaces. This suggests that the function of the complement system and the major histocompatibility complex may be related.