A neutral beam sciopticon

A sciopticon based on the pinhole-camera effect is being used to determine individual beamlet contributions to the quality of neutral beams extracted from multiaperture ion sources. The technique outlined in this note can be used to study the effects on beam optics of nonhomogeneous source plasma density or acceleration gap nonuniformities, grid nonparallelism or aperture misplacement, and space-charge blowup or scattering in the neutralizer cell.

Properties of an intense 40-kV neutral beam injector

The properties of an intense neutral beam injector, the modified duoPIGatron ion source, are discussed and compared with other injectors. For this source (a) beam composition for hydrogen is approximately (85+/-5) % monatomic, (b) nucleon gas efficiency is 50%, (c) the electrical efficiency of ion generation is 1.1 A/kW, and (d) up to 52% of the input power is delivered in the ion and neutral beam to a target subtending a half angle of 1.8 degrees x1.4 degrees .

De novo development of membranous nephropathy in cadaver renal allografts

Glomerulonephritis in transplant recipients often reflects recurrence of the immunopathogenetic mechanism causing the original renal disease. Membranous nephropathy (MN), a progressive immune complex mediated glomerular disease and the commonest cause of idiopathic nephrotic syndrome in adults, has been virtually unreported in transplant recipients. Two cases are reported here of typical MN (by clinical, light, immunofluorescent and electron microscopic criteria) developing de novo in the transplants of patients whose original diseases were anti-GBM nephritis and focal glomerular sclerosis. NM developed following episodes of viral hepatitis and renal infarction respectively. Possible mechanisms by which this lesion might develop in these patients are investigated and discussed. Chronic immune complex nephropathy (MN) can develop de novo in immunosuppressed transplant recipients apparently initiated by events in the post-transplant period.

Circular dichroism of cobaltous complexes of creatine kinase

Circular dichroic spectra in the visible wavelength region were used to investigate the local environment of Co(II), an activating metal, at the active site of rabbit muscle creatine kinase. There was a small spectral change when CoADP- was bound to creatine kinase, no change when creatine was added, and another small change when NO3- was added to form the transition state analogue. Using matrix rank analysis to quantitate these small spectral changes, a titratable group with a pK = 7.4 was found which modified the enzyme-bound metal-nucleotide interaction. These data suggest that, throughout the enzyme's catalysis, the metal-nucleotide interaction remains very similar in structure to the complex not bound to the enzyme.

A comparison of the late patency rates of axillobilateral femoral and axillounilateral femoral grafts

A total of 130 axillofemoral grafts were peformed in 120 patients from 1966 to present; 66 were axillobilateral femoral moral and 64 were axillounilateral femoral grafts. The average patient age was 66 years. The indications for operation were occlusive disease with rest pain or gangrene in 102 patients, severe claudication four, and bypass of a thoracic aneurysm in one. The one month operative mortality rate was 8 percent (ten patients). Four deaths occurred in elderly patients operated upon as emergencies with acute aortic occlusion. In the 126 elective cases, there were six postoperative deaths (4.7 percent). Twenty thrombectomies were performed in 15 axillobilateral femoral grafts of which 15 (75 percent) were successful. In the unilateral grafts there were 25 thrombectomies in 22 grafts, of which only eight (32 percent) were successful. The 5 year patency rate by the life-table method was 74 percent for axillobilateral femoral grafts and 37 percent for axillounilateral femoral grafts. This difference in patency rates is statistically significant (p < 0.01). Average flow measured by electromagnetic flow meter in six axillobilateral femoral grafts was 621 c.c. per minute and in 11 unilateral femoral grafts was 273 c.c. per minute. We attribute the higher patency rate in axillobilateral femoral grafts to this increased flow. These data indicate that axillobilateral femoral grafts may be performed with anticipation of a 5 year patency rate comparable to that with conventional aortoiliac reconstruction and that axillobilateral femoral grafts should be performed in preference to axillounilateral femoral grafts in poor-risk patients requiring extra-anatomic bypass for aortoiliac occlusive disease.

Prolongation of allograft survival by combination therapy with anti-thymocyte serum and anti-immunoglobulin

Heterologous anti-immunoglobulin (AI) is a potent immunosuppressive agent which compares favorably to anti-thymocyte serum (ATS) in inhibiting E and EAC-rosette formation and diminishing the secondary antibody response to sheep erythrocytes and E. coli lipopolysaccharide. AI prolongs H-2 incompatible skin allograft survival than either antiserum used alone, without evidence of toxicity to recipient mice. AI does not cause significant immune complex glomerular or renovascular deposition and may act by interference with antigen binding.

Phosphoenolpyruvate hydrolase activity of rabbit muscle pyruvate kinase

Rabbit muscle pyruvate kinase catalyzes the hydrolysis of P-enolpyruvate at the same active site which catalyzes the physiologically important kinase reaction. The hydrolase activity is lower than the kinase activity by a factor of at least 10(3). There are specific monovalent cation and divalent cation requirements. No other cofactors are required. The relative activation of the pyruvate kinase for the hydrolase reaction is: Ni(II) greater than Co(II) greater than Mg(II) greater than Mn(II). This parallels the rates of nonenzymatic hydrolysis of P-enolpyruvate (Benkovic, S.J., and Schray, K.J. (1968) Biochemistry 7, 4097-4102). The pH rate profiles of the hydrolase and kinase reactions activated by Ni(II) and Co(II) are similar, suggesting common features in their mechanisms. In contrast to the kinase reaction, the reaction velocity of the hydrolase increases at high Co(II) concentrations indicating a second mode for hydrolysis.

Spectral properties of Co(II)- and Ni(II)-activated rabbit muscle pyruvate kinase

Stoichiometry, kinetics, and optical properties of rabbit muscle pyruvate kinase activated with Co(II), Ni(II), Mg(II), and Mn(II) were studied. The stoichiometry of metal binding to enzyme was found to be 4 metal ions per tetrameric enzyme for Co(II) and Ni(II) by carrying out circular dichroic titrations. Cu(II) and Fe(II) were inactive. Ca(II) and Zn(II) were not activating, and were inhibitory with respect to all of the active cations. The temperature dependence of the optimal velocity is similar for all activating metals. The pH rate profiles suggest that there are two classes of enzyme activation by metal ions. Mg(II) and Mn(II) are quite similar to each other while Co(II) and Ni(II) are different from them but similar to each other. Absorption, natural, and magnetic CD in the visible region were used to probe the environment of the activating divalent cation in Ni(II)- and Co(II)-activated pyruvate kinase and their complexes with substrates and inhibitors...

Successful renal transplantation in focal glomerular sclerosis: report of two cases

The fate of renal allografts has provided much useful information about the pathogenesis of certain glomerular diseases. Idiopathic nephrotic syndrome with focal glomerular sclerosis (FGS) has been reported to recur in transplants. Two patients are reported with idiopathic nephrotic syndrome who progressed to renal failure. Immunopathologic and ultrastructural studies appeared to exclude immune pathogenic mechanisms in both patients, and light microscopic findings were characteristics of FGS. The nephrotic syndrome in one patient was initially steroid-dependent. Both patients underwent bilateral nephrectomy prior to renal transplantation. Graft function and urine protein excretion were normal in both patients 2 and 4 years respectively after transplantation, and transplant biopsies revealed no evidence of recurrent FGS. These results indicate that renal transplantation in patients with idiopathic nephrotic syndrome and FGS is not invariably followed by recurrent glomerular disease and suggest that the responsible pathogenetic mechanism(s) may not always persist.

Bypass vein grafts in patients with distal popliteal artery occlusion

The results obtained by placing reversed autogenous saphenous vein bypass grafts in either isolated popliteal artery segments or tibial vessels distal to the popliteal artery segments or tibial vessels distal to the popliteal artery are compared. Fifty-five patients with arteriosclerotic peripheral vascular disease who were threatened with limb loss were followed up from six months to nine years prior to this report. The success rate at one year was 94 per cent for the isolated popliteal segment grafts and 73 per cent for the tibial vessel grafts. The success rate after four years was 70 per cent for the isolated popliteal segment grafts and 63 per cent for the tibial vessel grafts. The clinical factors associated with the success of isolated popliteal segment bypass grafts and the factors apparently associated with failure of vein grafts in both of these groups with very poor distal arterial outflow are discussed. Our results suggest that either an isolated popliteal artery segment graft or a tibial vessel graft is a satisfactory means of treating these patients; however, a graft to an isolated popliteal segment is probably preferable to a graft to a tibial artery.

Effect of rabbit ALG on cadaver kidney transplant survival

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The role of the graft in the induction of tolerance by antilymphocyte serum and cellular antigen

Intravenous donor antigen in the form of spleen cells can significantly potentiate the effects of ALS in prolonging the survival of skin allografts exchanged across both weak and strong histocompatibility barriers. This effect depends on the proper timing of antigen administration and can result in immunologic unresponsiveness of sufficient strength to permit acceptance of second set grafts. The skin allograft itself apparently plays a role in the establishment of this unresponsive state since ALS and antigen alone followed by delayed allografts at 21 days resulted in normal graft rejection times.

The effects of immunosuppression on the induction and immunogenicity of chemically induced sarcomas

The induction of chemically induced sarcomas does not appear to be accelerated by immunosuppression with antilymphocyte serum. Tumors induced in immunosuppressed mice contain tumor-specific transplantation antigens of antigenic strength comparable to that of those produced in normal hosts. Transplanted tumors will appear and grow more quickly in ALS-treated mice. Moreover, ALS pretreatment can block the recognition of and response to tumor-specific transplantation antigens.