Comparison of Arterial and Venous Interposition Grafting for Arterial Defects in a Rat Model.

BACKGROUND: Interposition microvascular grafting may be required to bridge arterial defects during digital replantation or revascularization and has traditionally been performed utilizing a venous autograft. Arterial interposition grafting has been shown to be superior in maintaining patency in large vessel surgery; there are case reports of its use in microsurgery. METHODS: Six fellowship-trained hand and microsurgeons performed arterial and venous interposition grafts on the femoral arteries of 40 Wistar rats. After sectioning one femoral artery a segment of the contralateral femoral artery or vein was obtained. The time was recorded per graft and patency tested 10 minutes following grafting by an independent assessor. Each surgeon also completed a questionnaire detailing regular microsurgical volume, technical ease, and conceptual preference for either graft. RESULTS: Time for arterial interposition (median time 51.7 minutes) was longer than venous grafting (median time 45.9 minutes, p = 0.075). Arterial grafts were more likely to be patent or questionably patent (odds ratio [OR] = 6.77, p = 0.031). All surgeons found arterial interposition grafting technically easier and preferred it conceptually. Improvements were noted in patency rates (OR = 11.29, p = 0.018) and avoidance of anastomotic leak (OR = 0.19, p = 0.029) when surgeons performed moderate levels or greater of microsurgery within their regular practice. CONCLUSION: Greater immediate patency was noted with arterial interposition grafting in a rodent model when compared to venous grafting, although procedural time was greater. All surgeons found arterial grafting technically easier. Arterial microvascular grafting may be useful in the setting of digital replantation or revascularization with an arterial defect.

Prostate specific antigen releases a kinin-like substance on proteolysis of seminal vesicle fluid that stimulates smooth muscle contraction.

PURPOSE: We investigated whether purified prostate specific antigen (PSA), a seminal plasma serine protease of the kallikrein enzyme family, is capable of releasing kinin-like peptides from natural substrate glycoproteins in human seminal vesicle fluid. MATERIALS AND METHODS: An in vivo rat bladder model was used to monitor for release of substances capable of inducing smooth muscle contractions. Purified PSA, seminal vesicle fluid (SVF) from radical prostatectomy specimens, bradykinin, saline and a bradykinin antagonist were injected intravesically into urethane-anesthetized rats, and the resulting bladder contractions were measured. RESULTS: Injection of either PSA or SVF alone did not induce bladder contractions. Injection of a mixture of SVF and PSA preincubated 15 minutes, however, induced strong bladder contractions (23 +/- 7 cm. H2O) that decreased with time (4 +/- 2 cm. H2O, after 90 minutes). Similar contractions were observed after injection of bradykinin (10(-4) M. = 39 +/- 14, 10(-6) M. = 27 +/- 9, 10(-8) M. = 7 +/- 4 cm. H2O). Addition of a bradykinin antagonist to the PSA-SVF mixture prior to injection blocked the observed bladder contractions (23 +/- 7 cm. H2O before, versus 0.3 +/- 1.2 cm. H2O after adding antagonist). CONCLUSIONS: We conclude that PSA produces a kinin-like substance by enzymatic cleavage of glycoproteins in human seminal fluid. This substance induces smooth muscle contractions which can be specifically blocked by addition of a bradykinin antagonist.

Quantitating and engineering the ion specificity of an EF-hand-like Ca2+ binding.

The Escherichia coli D-galactose and D-glucose receptor, an aqueous periplasmic receptor that triggers sugar sensing and transport, possesses a single Ca2+ binding site similar in structure and specificity to the EF-hand class of sites found in eukaryotic Ca2+ signaling proteins including calmodulin and its homologues. A universal feature of these sites is the use of a pentagonal bipyramidal array of seven oxygens to coordinate bound Ca2+. Here we investigate the mechanisms used by this coordinating array to control ion specificity. To vary the cavity size and charge of the array, we have replaced axial glutamine 142 in the prokaryotic site with asparagine, glutamate, and aspartate. The ion selectivities of the resulting engineered sites have been quantitated by measuring dissociation constants for a series of spherical metal ions, differing in increments of radius and charge, from groups Ia, IIa, and IIIa and the lanthanides. Dramatic specificity changes are observed: sites containing an engineered smaller side chain (Asn or Asp) bind the largest cations up to 50-fold more tightly than the native site; and sites containing an engineered negative side chain (Glu or Asp) exhibit preferences for trivalent over divalent cations up to 1900-fold higher than the native site. The results indicate that the cavity size and negative charge of the coordination array play key roles in selective Ca2+ binding and that the array can be engineered to preferentially bind other cations.

The psychiatric abortion consultation.

The role of the psychiatric consultant has changed with the recent liberal "on demand" abortion legislation. This paper emphasizes factors relevant to the psychiatric consultant in the evaluation of the adolescent patient, the retarded patient and the patient with psychiatric illness. In addition, a survey of the literature is made to identify the patient who is at high risk of developing postabortion psychiatric complications. The authors conclude that postabortion complications are infrequent and that there are no absolute psychiatric contraindications to elective abortion.