Immune consequences of intraocular administration of modified adenoviral vectors

To investigate the immune consequences of intraocular administration of modified adenoviral vectors, C57BL/6 normal and retinal degeneration C57BL/6 (rd/rd) mice were immunized with subcutaneous, subretinal, vitreal, or anterior chamber injections of replication-deficient adenovirus (AdV) containing the Escherichia coli beta-galactosidase gene (AdV-LacZ). Fourteen days after the initial inoculation, the animals were immune challenged with an injection of AdV-LacZ in the right ear pinna. Antigen-induced delayed type hypersensitivity (DTH) was measured by determining relative ear swelling. Normal C57BL/6 mice immunized with subretinal, vitreal, or anterior chamber injections did not demonstrate a DTH response. The rd/rd C57BL/6 mice injected in the anterior chamber with the viral construct also did not respond with DTH in a manner similar to normal mice responding to intraocular injection and subsequent challenge. However, the rd/rd C57BL/6 mice immunized by the subretinal or vitreal route did respond to immune challenge with a DTH response. Histologic examination of the eyes showed a lack of infiltration by inflammatory cells. Although these results suggest that the potential for immune consequences is reduced when modified adenoviral vectors are used in the normal ocular environment, these vectors used in the vitreal cavity of rd/rd animals may induce a systemic response to the vectors.

Metastatic and nonmetastatic models of retinoblastoma

To generate animal models of retinoblastoma that closely resemble metastatic and nonmetastatic human disease for the purposes of examining tumor biology and developing alternate treatments, human retinoblastoma cell lines were injected into the vitreal cavities of immunodeficient mice. Two reproducible animal models with contrasting biological behaviors analogous to human retinoblastoma have been developed. The Y79 retinoblastoma model demonstrated specific tumor evolution similar to that seen in human invasive and metastatic disease. Y79 retinoblastoma cells formed intraocular tumors that were initially confined to the vitreal cavity. Tumors progressively invaded the retina, subretinal space, choroid, optic nerve head, and anterior chamber of the eye. Tumors progressed into the subarachnoid space and focally invaded the brain. Metastases were detected in the contralateral optic nerve. Large tumors developed extraocular extensions. The histology of the tumors showed a poorly differentiated pattern with high mitotic rate, foci of necrosis, and calcification. The WERI-Rb model more closely resembled nonmetastatic human retinoblastoma. WERI- Rb tumors were localized in the eye with only anterior choroidal invasion at late stages. To examine potential biological differences in vitro, the retinoblastoma cell lines were cocultured with adherent choroid cells or adherent glioma cells which represent the targets of invasive retinoblastoma in vivo. Consistent with the in vivo observations, Y79 cells but not WERI-Rb cells adhere specifically to both the choroidal and the glioma cell lines.

Mycophenolate mofetil, with cyclosporine and prednisone, reduces early rejection while allowing the use of less antilymphocytic agent induction and cyclosporine in renal recipients with delayed graft function

Antilymphocytic agent induction (ALAI), with antithymocyte globulin or monoclonal antibody, is generally used in renal transplantation (TX) to spare renal allografts with poor initial function from the toxic effects of cyclosporine (CsA) and/or to augment immunosuppression (IS) in the patient at a high risk for early rejection. ALAI, unfortunately, increases the cost of TX and the risk to the patient, having been associated with many adverse side effects. An IS protocol, which results in a low incidence of early rejection while using less CsA and ALAI, is a worthwhile goal. We compare our experience with mycophenolate mofetil (MMF), CsA, and prednisone (MMFCP; n = 62) to our azathioprine (AZA), CsA, and prednisone (AZACP; n = 50) triple-drug IS, with and without ALAI. The patient characteristics for age, race, first TX, cadaveric donor, pediatric recipient, and dialysis in the first post-op week (DGF) were not different for the MMFCP versus AZACP groups. There were more females in the MMFCP group (51.6% versus 30.0%, p = 0.022). We report that rejection-free survival at 6 months (RF6) was better in the MMFCP versus AZACP group (83.9% versus 60.0%, p = 0.005). Less ALAI and CsA were used in the MMFCP patients. At 1 year, actuarial graft survival was 91.9% in the MMFCP group and 81.9% in the AZACP group (p = 0.116). Actuarial 1-year patient survivals were not different in the two patient groups. In the sub-population of patients with DGF, the RF6 in the MMFCP (n = 13) group was 92.3% versus 57.1% in the AZACP (n = 14) group (p = 0.041). The reduction in early rejection episodes in the patients on MMFCP with DGF was accomplished while using half as much ALAI and lower CsA doses and levels. The African-American recipient sub-population on MMFCP also demonstrated an improvement in RF6 while using less ALAI and CsA (78.6% versus 48.0%, p = 0.022). We conclude that the use of MMF-based triple-drug IS results in fewer rejection episodes while allowing for lower CsA levels and less ALAI, even in patients with delayed graft function.

Suicide gene therapy for treatment of retinoblastoma in a murine model

Children presenting with large retinoblastomas are currently treated by enucleation. As most patients are young children, the long-term repercussions of such surgery are often devastating. Subsequent radiation or chemotherapy, although effective in managing residual tumor, greatly increase the probability of the development of second malignancies later in life. Smaller tumors can sometimes be managed with local cryo- or laser surgery, thus saving the eye. The hypothesis that gene therapy could be used to reduce the tumor size sufficiently to allow local control was tested using a murine model of retinoblastoma. Y79Rb human retinoblastoma cells can be killed in vitro when transduced with an adenoviral vector containing the herpes simplex thymidine kinase gene (AdV-TK) followed by treatment with the prodrug ganciclovir. Intravitreal injections of Y79Rb cells in immunodeficient mice produce an aggressive, metastatic murine model of retinoblastoma. When these murine retinoblastomas were transduced in vivo with AdV-TK and the animals treated with intraocular injections of ganciclovir, 70% showed a complete ablation of detectable tumor. Treated animals had a significant prolongation of progression-free survival as compared with untreated controls. Gene therapy effectively reduced the tumor burden in this murine model of retinoblastoma. Thus gene therapy, in conjunction with local surgical control, may provide an effective alternative to enucleation, systemic chemotherapy, or radiotherapy for treatment of large, nonmetastatic retinoblastomas in children.

Distal revascularization-interval ligation for limb salvage and maintenance of dialysis access in ischemic steal syndrome

PURPOSE

Traditional options for treating ischemic steal syndrome related to a functioning dialysis access graft or fistula include banding or ligation. Unfortunately, these techniques usually result in inconsistent limb salvage, loss of a functional access, or both. We report our experience with an alternative method of limb revascularization that eliminates steal while maintaining continuous dialysis access.

METHODS

Patients who had critical limb ischemia and functioning arteriovenous fistulae (AVF) underwent color-flow duplex scanning, digital photoplethysmography, and arteriography. Arterial ligation distal to the AVF origin eliminated the steal physiologic mechanism while arterial bypass grafting from above to below the AVF revascularized the extremity (distal revascularization-interval ligation [DRIL] procedure).

RESULTS

From March 1994 through December 1996, 21 patients with functioning extremity AVFs presented with critical ischemia and steal syndrome. Eleven patients had chronic ischemia with rest pain, paresthesias, or ulcerations related to nine native fistulae (six brachiocephalic, two basilic vein transpositions, one radiocephalic) and two prosthetic bridge grafts (one upper arm, one lower extremity). Acute ischemia developed in 10 patients related to three native fistulae (two brachiocephalic, one radiocephalic) and seven prosthetic bridge grafts (three forearm, three lower extremity, one upper arm). All 21 patients were treated with the DRIL technique. Three of these patients required treatment for ischemia at the time of AVF construction. Nineteen of 21 bypass procedures were performed with autogenous vein, including nine brachial-brachial, three brachial-radial, two radial-radial, two brachial-ulnar, one popliteal-popliteal, one femoral-popliteal, and one femoral-peroneal. Polytetrafluoroethylene grafts were used for one external iliac-popliteal bypass graft and one axillary-brachial bypass graft. Limb salvage and maintenance of a functional fistula were achieved in 100% and 94%, respectively, at 18 months by life-table analysis.

CONCLUSION

The DRIL technique reliably restores antegrade flow to the ischemic limb, eliminates the potential pathway for the steal physiologic mechanism, and maintains continuous dialysis access in these difficult patients.

Cloning and analysis of the cDNA encoding the rod G-protein transduction alpha, beta1 and gamma1 subunits from the canine retina

The canine (Canis familiaris) retinal rod transducin (G(T)) alpha, beta1 and gamma1 subunits were sequenced. Cloning of the cDNAs was accomplished by polymerase chain reaction (PCR) using degenerate and wild type retinal cDNA libraries as templates. The deduced amino acid sequences were highly similar to rod transducins from other species: G(T alpha) differed by 5 amino acids from the corresponding human sequence, whereas beta1 and gamma1 were identical to human sequences. The coding sequence of rod transducin was evaluated as a possible cause for the recessively inherited retinal rod-cone degeneration: there were no nucleotide differences between the wild type and retinal degenerate strains.

Cloning of the cDNA encoding rod photoreceptor cGMP-phosphodiesterase alpha and gamma subunits from the retinal degenerate Labrador retriever dog

The nucleotide (nt) sequence of the cDNA encoding the retinal rod cyclic 3'5'-GMP phosphodiesterase (PDE) alpha and gamma subunits from two strains of dogs-(i) Labrador Retrievers homozygous for autosomally recessively inherited rod-cone degeneration and (ii) the wild-type Beagle-are reported. Cloning of these subunits was accomplished by polymerase chain reaction using retinal cDNA libraries as templates. The nt sequence of alpha PDE predicts a 861-amino-acid polypeptide which is 97.7 per cent and 96.9 per cent identical to the bovine and human counterparts, respectively. PDE gamma encodes an 87-amino-acid polypeptide differing from bovine and murine gamma subunits by only one amino acid. Since no differences were found between these two strains of dogs, the cause of the Labrador Retriever's degeneration remains to be determined.

Lymphoblastic lymphoma following prenatal exposure to phenytoin

PURPOSE

Oncogenesis has been associated with prenatal exposure to phenytoin, concomitant with or independent of the fetal hydantoin syndrome. The majority of reported cases have been embryonal tumors of neural crest origin and have occurred in the first 3 years of life.

PATIENTS AND METHODS

We report a boy who was exposed to phenytoin throughout gestation and later developed T-lymphocyte lymphoblastic lymphoma, a previously unreported malignancy associated with in utero phenytoin exposure. Previously reported cases of neoplasia occurring after such exposure are tabulated.

CONCLUSION

The actual transplacental oncogenic potential of phenytoin and the epidemiology of this association are poorly understood. Phenytoin-induced alterations in lymphocyte-mediated immunosurveillance or oxidative metabolic clearance may be etiologic. Inquiry into prenatal phenytoin exposure should be done in any child who develops cancer, especially those who develop a rare tumor or present with a more common tumor at an unusually young age. Continued documentation of such cases will advance the understanding of phenytoin-associated transplacental oncogenesis.

Elevation of cGMP with normal expression and activity of rod cGMP-PDE in photoreceptor degenerate labrador retrievers

Cyclic guanosine 3',5'-monophosphate (cGMP) levels were determined in retinas from a strain of Labrador Retrievers with inherited retinal dystrophy manifesting at early stages of retinal differentiation. The cGMP contents of dystrophic retinas of dogs from 1 to 4 months of age (n = 7) were significantly higher (p = 0.001) than in age-matched controls of the same breed (n = 11). Ultrastructure along the vertical retinal meridian was studied in developing retinas and findings were related to those of age-matched wild-type controls of the same breed. Slow central to peripheral progression of degeneration was observed in affected dogs. No differences were found in total cGMP-phosphodiesterase (PDE) activity, in PDE subunit composition as determined by Western blotting of 2-month-old homozygote affected retinas, or in the amino acid sequence deduced from the nucleotide sequence of the PDE beta-subunit as compared to controls. This model of photoreceptor degeneration thus is the first case of an apparent abnormality of cGMP metabolism that is not associated with a defect in the PDE catalytic subunits, and it is also the first reported model not associated with severe developmental abnormalities and rapid degeneration.

The mammalian pineal expresses the cone but not the rod cyclic GMP phosphodiesterase

To determine the presence of cone or rod cyclic GMP phosphodiesterase (EC 3.1.4.17) in the mammalian pineal, extracts from adult rat and bovine pineals were injected onto a Mono Q anion-exchange HPLC column and eluted with an NaCl linear gradient. Fractions were immunoadsorbed with monoclonal antibodies specific to rod and cone phosphodiesterases (ROS-1) and to calmodulin-phosphodiesterase complexes (ACC). Profiles were assayed with 10 mumol/L [3H]cyclic GMP in the presence of calcium-calmodulin, histone, or trypsin. Rat and bovine pineals displayed a single peak of activity recognized by ROS-1, which corresponded to the activity of the cone but not to the rod in bovine retina. ROS-1 immunoadsorbed approximately 80% of the activity in the 60-day-old rat pineal but only 26% of the activity in bovine pineal. ACC immunoadsorbed the remaining activity in both species. Western blot analysis of rat pineal extracts revealed three polypeptides of approximately 87, 15, and 10 kDa when probed with a rod/cone phosphodiesterase-specific antiserum. The specific activity of the cone-like phosphodiesterase in 10-day-old rat pineals was twice that of this isozyme in the bovine retina and 150 times that in the bovine pineal. The specific activity of phosphodiesterase in rat pineals decreased with age. We conclude that an enzyme with biochemical and antigenic characteristics similar to cone, but distinct from rod phosphodiesterase, is present in bovine and rat pineals.

Lead- and calcium-mediated inhibition of bovine rod cGMP phosphodiesterase: interactions with magnesium

Previously we showed that cGMP hydrolysis in rat whole retinal homogenates exhibited a dose-dependent inhibition following developmental lead exposure and a concentration-dependent inhibition with direct Pb2+ exposure. Additionally, developmental lead exposure resulted in a dose-dependent increase in retinal cGMP and rod Ca2+ levels. To determine whether Pb2+ or Ca2+ directly inhibited the rod-specific cGMP phosphodiesterase (PDE) and to examine the kinetic mechanism of this inhibition, purified bovine rod cGMP PDE was assayed in the presence of varying concentrations of cGMP, and Mg2+, Pb2+, and/or Ca2+. Increasing concentrations of the substrate, cGMP, resulted in a shift of the Pb2+ and Ca2+ concentration-response curves to the left, indicating a decrease in the half-maximal inhibitory concentrations of Pb2+ from nanomolar to picomolar levels. Increasing concentrations of the cofactor, Mg2+, resulted in a shift of the Pb2+ and Ca2+ concentration-response curves to the right, indicating a decrease in the inhibition of PDE activity by Pb2+ or Ca2+. A plot of 1/velocity vs 1/Mg2+ as a function of Pb2+ revealed that picomolar concentrations of Pb2+ competitively inhibited PDE relative to millimolar concentrations of Mg2+. Consistent with this finding, Mg2+ reversed the Pb(2+)-induced inhibition of PDE. Our recent kinetic analysis showed that Mg2+ and cGMP bind at interacting sites on the PDE in a random order. The present results reveal that Pb2+ may bind at the same site but with 4-6 log units higher affinity than Mg2+, thus preventing the hydrolysis of cGMP. These findings provide a novel mechanism for understanding the Pb(2+)-induced inhibition of cGMP PDE. These results may have implications for other enzymes using Mg2+ as a cofactor and suggest that Mg2+ may be useful in these situations for reversing the inhibition by Pb2+.

Effects of magnesium on cyclic GMP hydrolysis by the bovine retinal rod cyclic GMP phosphodiesterase

Knowledge of the kinetics of the rod cyclic GMP phosphodiesterase is essential for understanding the kinetics and gain of the light response. Therefore, the interactions between Mg2+, cyclic GMP, and purified, trypsin-activated bovine rod cyclic GMP phosphodiesterase (EC 3.1.4.17) were examined. The effects of Mg2+ and of cyclic GMP on the rod phosphodiesterase activity were mutually concentration-dependent. Formation of a free Mg-cyclic GMP complex is unlikely due to its high dissociation constant (Kd = 19 mM). Plots of 1/velocity versus 1/[cyclic GMP] as a function of [Mg2+] and 1/velocity versus 1/[Mg2+] as a function of [cyclic GMP] intersected to the left of the 1/velocity axis. This is consistent with the formation of a ternary complex between the phosphodiesterase, Mg2+, and cyclic GMP. A competitive inhibitor of the phosphodiesterase relative to cyclic GMP, 3-isobutyl-1-methylxanthine, non-competitively inhibited the enzyme relative to Mg2+, Pb2+, a competitive inhibitor of the phosphodiesterase relative to Mg2+ [D. Srivastava, R.L. Hurwitz and D. A. Fox (1995) Toxicol. Appl. Pharmacol, in the press] non-competitively inhibited the enzyme relative to cyclic GMP. Collectively these results are suggestive of a rapid equilibrium random binding order of Mg2+ and cyclic GMP to the rod phosphodiesterase.

Irish setter dogs affected with rod/cone dysplasia contain a nonsense mutation in the rod cGMP phosphodiesterase beta-subunit gene

Irish setter dogs affected with a rod/cone dysplasia (locus designation, rcd1) display markedly elevated levels of retinal cGMP during postnatal development. The photoreceptor degeneration commences approximately 25 days after birth and culminates at about 1 year when the population of rods and cones is depleted. A histone-sensitive retinal cGMP phosphodiesterase (PDE; EC 3.1.4.35) activity, a marker for photoreceptor PDEs, was shown previously to be present in retinal homogenates of immature, affected Irish setters. Here we report that, as judged by HPLC separation, this activity originates exclusively from cone photoreceptors, whereas rod PDE activity is absent. An immunoreactive product the size of the PDE alpha subunit, but none the size of the beta subunit, can be detected on immunoblots of retinal extracts of affected dogs, suggesting a null mutation in the PDE beta-subunit gene. Using PCR amplification of Irish setter retinal cDNA, we determined the complete coding sequence of the PDE beta subunit in heterozygous and affected animals. The affected PDE beta-subunit mRNA contained a nonsense amber mutation at codon 807 (a G-->A transition converting TGG to TAG), which was confirmed to be present in putative exon 21 of the affected beta-subunit gene. The premature stop codon truncates the beta subunit by 49 residues, thus removing the C-terminal domain that is required for posttranslational processing and membrane association. These results suggest that the rcd1 gene encodes the rod photoreceptor PDE beta subunit and that a nonsense mutation in this gene is responsible for the production of a nonfunctional rod PDE and the photoreceptor degeneration in the rcd1/rcd1 Irish setter dogs.

Dominant thalassemia-like phenotypes associated with mutations in exon 3 of the beta-globin gene

Mutations producing beta-thalassemia reach individual gene frequencies greater than .01 in malarial-endemic regions because beta-thalassemia trait individuals have increased genetic fitness over that of normal individuals. Exon 3 of the beta-globin gene has been relatively spared as a site of common beta-thalassemia mutations. Frameshifts caused by the loss of a single nucleotide and nonsense mutations produce beta-thalassemia trait when they occur in exons 1 and 2. In contrast, they usually produce chronic hemolytic anemia when present in exon 3. Certain missense mutations in exon 3 produce unstable globins and thalassemia intermedia with hemolysis in heterozygotes. Here we report two new mutations in exon 3 of the beta-globin gene. One is a single nucleotide deletion in codon 109 in a 78-year-old Lithuanian with chronic hemolytic anemia and features of thalassemia. It leads to an abnormal globin (beta Manhattan) that is elongated to 156 amino acids. The second is a CAG-CGG missense mutation at codon 127 that causes a Gln----Pro substitution (beta Houston) and a thalassemia intermedia with hemolysis in three generations of a British-American family. Although the clinical phenotypes of these two patients differed little, differences in globin-synthetic ratios were significant, presumably reflecting differences in the ability of each abnormal beta-globin to form alpha beta dimers. The paucity of high-frequency exon 3 mutations and their worldwide distribution is likely attributable to their phenotypic severity and loss of increased genetic fitness vis-a-vis malaria.

Primary structure and chromosomal localization of human and mouse rod photoreceptor cGMP-gated cation channel

We have determined the primary structures of the human and mouse retinal rod cGMP-gated cation channel by analysis of cDNA clones and amplified DNA. The open reading frames predicted polypeptides of 690 and 683 residues exhibiting 88% sequence similarity. Sequence comparison indicated that the rod channels consist of a variable 90-residue N-terminal region, a short highly charged segment rich in lysine and glutamate, and a 540-residue C-terminal portion that is well conserved in three mammalian species. Significant sequence similarity (59%) of the visual cGMP-gated channel to the olfactory cAMP-gated channel established the existence of a family of cyclic nucleotide-gated ion channel genes. RNA blot analysis revealed transcripts of 3.2 kilobases (kb) in human, mouse, and dog, 3.2, 4.6, and 5.2 kb in bovine, and 3.6 kb in fish. The human channel gene was mapped by polymerase chain reaction of somatic cell hybrid DNAs to chromosome 4 (p14-q13) near the centromere. The mouse channel gene locus (Cncg) was mapped by interspecific backcross haplotype analysis 0.9 centimorgan proximal of the Kit locus on chromosome 5.

Transmission of human immunodeficiency virus type 1 from a seronegative organ and tissue donor

BACKGROUND

Since 1985, donors of organs or tissues for transplantation in the United States have been screened for human immunodeficiency virus type 1 (HIV-1), and more than 60,000 organs and 1 million tissues have been transplanted. We describe a case of transmission of HIV-1 by transplantation of organs and tissues procured between the time the donor became infected and the appearance of antibodies. The donor was a 22-year-old man who died 32 hours after a gunshot wound; he had no known risk factors for HIV-1 infection and was seronegative.

METHODS

We reviewed the processing and distribution of all the transplanted organs and tissues, reviewed the medical histories of the donor and HIV-1-infected recipients, tested stored donor lymphocytes for HIV-1 by viral culture and the polymerase chain reaction, and tested stored serum samples from four organ recipients for HIV-1 antigen and antibody.

RESULTS

HIV-1 was detected in cultured lymphocytes from the donor. Of 58 tissues and organs obtained from the donor, 52 could be accounted for by the hospitals that received them. Of the 48 identified recipients, 41 were tested for HIV-1 antibody. All four recipients of organs and all three recipients of unprocessed fresh-frozen bone were infected with HIV-1. However, 34 recipients of other tissues--2 receiving corneas, 3 receiving lyophilized soft tissue, 25 receiving ethanol-treated bone, 3 receiving dura mater treated with gamma radiation, and 1 receiving marrow-evacuated, fresh-frozen bone--tested negative for HIV-1 antibody. Despite immunosuppressive chemotherapy, HIV-1 antibody appeared between 26 and 54 days after transplantation in the three organ recipients who survived more than four weeks.

CONCLUSIONS

Although rare, transmission of HIV-1 by seronegative organ and tissue donors can occur. Improvements in the methods used to screen donors for HIV-1, advances in techniques of virus inactivation, prompt reporting of HIV infection in recipients, and accurate accounting of distributed allografts would help to reduce further this already exceedingly low risk.

Chronic relapsing thrombotic thrombocytopenic purpura in infants with large von Willebrand factor multimers during remission

We studied two children with recurrent schistocytic hemolytic anemia and thrombocytopenia beginning in the neonatal period. One patient had a stroke during one of the episodes of thrombotic thrombocytopenic purpura. The presence of unusually large von Willebrand factor multimers was demonstrated in both children during clinical and hematologic remissions. Treatment with corticosteroids and intravenous injections of immune globulin was unsuccessful in the one patient who received it. Immediate improvement occurred in both patients after the infusion of fresh-frozen plasma. Symptoms of thrombocytopenia continue to recur at regular intervals in the absence of periodic fresh-frozen plasma infusions. One of these children apparently has chronic relapsing thrombotic thrombocytopenic purpura; the second has a chronic relapsing disorder similar to thrombotic thrombocytopenic purpura.

Phosphodiesterase of cone photoreceptors from the lizard, Anolis carolinensis

Cone and rod photoreceptors utilize cyclic guanosine monophosphate (cGMP) in the light regulation of membrane polarization. The prototype for visual transduction is established for rod photoreceptors, which utilize a cascade of reactions to regulate a cyclic nucleotide phosphodiesterase (PDE) (EC 3.1.4.17) and thereby control the intracellular concentration of cGMP. Although cones appear to utilize a comparable cGMP cascade for their phototransduction, evidence exists that the PDE from cone photoreceptors may be different from that of rods. Dissociated cone photoreceptors, isolated retinas, and cone outer segments from the lizard, Anolis carolinensis, have been used to identify and characterize a PDE enzyme complex that shares several features in common with the rod outer segment (ROS) PDE complex. Immunoadsorption and sodium dodecyl sulfate-polyacrylamide gel electrophoresis have identified a subunit of lizard cone PDE that has an apparent electrophoretic mobility of 84 kDa and a subunit of lizard rod PDE that migrates at approximately 90 kDa. The lizard cone PDE complex is similar in size, extraction, activation, and immunological characteristics to the PDE complex of rod photoreceptors from lizard, bovine, and human retinas. The lizard cone PDE complex, and perhaps that from cone photoreceptors in general, differs from that of ROS in its chromatographic properties on anion-exchange resins. The sharing of physical and activation properties of the rod and cone PDE complex is compatible with the phototransduction process occurring by a similar mechanism in both cell types. The differences in light sensitivity and speed of response may be attributable to features of the individual proteins that form the PDE complexes of rods and cones or to other undisclosed features of the respective cascades.

Transplantation of horseshoe kidney into single recipient

A case of successful en bloc transplantation of a horseshoe kidney into a single recipient is reported. The literature is briefly reviewed. The use of horseshoe kidneys in transplantation is recommended in selected cases.

Expression of the functional cone phototransduction cascade in retinoblastoma

Retinoblastoma is a malignant intraocular tumor that primarily affects small children. These tumors are primitive neuroectodermal malignancies, however some of them show morphologic evidence of differentiation into photoreceptors. Phototransduction cascades are a series of biochemical reactions that convert a photon of light into a neural impulse in rods and cones. The components of these cascades are uniquely expressed in photoreceptors and, although functionally similar, distinct components of these cascades are expressed in rods and cones. Using HPLC anion exchange chromatography, Western blot analysis, and specific monoclonal and polyclonal antibodies, we found that the cone but not the rod cGMP phosphodiesterase is functionally expressed in all six primary retinoblastomas examined and in three continuous retinoblastoma cell lines. Morphologic evidence of differentiation did not correlate with the expression of the enzyme. Furthermore, GTP analogues could activate the phosphodiesterase activity suggesting that an intact phototransduction cascade is present in the tumors. The presence of the cone phototransduction cascade in retinoblastoma confirms that this tumor has biochemically differentiated along the cone cell lineage.

Induction of a calcium/calmodulin-dependent phosphodiesterase during phytohemagglutinin-stimulated lymphocyte mitogenesis

A calmodulin (CaM)-dependent phosphodiesterase activity that hydrolyzes both cGMP and cAMP was observed in anion exchange high performance liquid chromatography (HPLC) profiles from phytohemagglutinin-stimulated mononuclear cells but not in profiles from unstimulated cells. A single polypeptide was detected by an antibody to the calmodulin-dependent phosphodiesterases on a Western blot of homogenates of stimulated mononuclear cells. The phosphodiesterase activity was immunoadsorbed in a calcium-dependent manner by an antibody to calmodulin but not by an antibody to the 61-kDa bovine brain phosphodiesterase. The mononuclear cell enzyme eluted from the HPLC column in the same fractions as the 63-kDa calmodulin-dependent isozyme from bovine brain and appeared to have the same subunit molecular weight when probed on a Western blot. The electrophoretic mobility of proteolytic fragments derived from the mononuclear cell phosphodiesterase were identical to those from the 63-kDa brain isozyme. The enzyme could be detected in mononuclear cells by activity assays and on a Western blot 14 h after stimulation with mitogen. The enzyme remained elevated for at least 100 h after stimulation. A dose-response experiment with phytohemagglutinin demonstrated that similar concentrations of mitogen could induce both mitogenesis and the phosphodiesterase. The induction of this enzyme requires mRNA as well as protein synthesis but not DNA synthesis. An enzyme similar to the 63-kDa phosphodiesterase found in brain seems to demonstrate a regulatory interface for the metabolism of calcium and cyclic nucleotides during lymphocyte mitogenesis.

Thrombosed iliac venous aneurysm: a rare cause of left lower extremity venous obstruction

A patient who had deep venous obstruction of the left lower limb was shown to have thrombosis of a venous aneurysm of the left common iliac vein that measured 8.8 cm at the largest diameter. The aneurysm was suspected on the basis of preoperative noninvasive testing. Findings at surgery suggested the left iliac vein was being compressed by the right iliac artery. The aneurysm was resected and prosthetic graft material was used to reconstruct the venous system. A 22-month follow-up is recorded. Literature pertaining to the case is discussed.

Early experience utilizing the in situ saphenous vein technique in 54 patients

We have compared our early and late experience utilizing in situ saphenous vein bypass graft for lower extremity arterial occlusive disease in 54 patients who underwent in situ femoral to popliteal and distal bypass grafts between July of 1983 and February 1985. There were 3 femoral to above-knee popliteal bypasses, 27 femoral to below-knee popliteal bypass grafts, 12 femoral to anterior tibial dorsalis pedis bypass grafts, 10 femoral to posterior tibial bypass grafts and 2 femoral to peroneal in situ bypass grafts. The operative indications were progressive disabling claudication in 8 (15%) and limb salvage in 46 (85%). Eighty-nine percent of the limb salvage patients had 0-1 vessel runoff by arteriogram. Cumulative life table patency of the 54 in situ bypass grafts was 79% at 20 months. One hundred percent of the patients who were operated on for disabling claudication had patent grafts at 20 months. Seventy-eight percent of the limb salvage patients had patent grafts. Fourteen of the limb salvage patients required amputation and of these 14, 10 had patent grafts at the time of amputation. There were 8 deaths in the series. Our results demonstrate that a definite learning curve exists with this technique, however, once established, long-term patency and improved limb salvage statistics can be obtained.

Reversible encephalopathy and seizures as a result of conventional vincristine administration

An 8-year-old child with acute lymphoblastic leukemia (ALL) developed seizures associated with bilateral lucencies on CT scan during standard induction therapy with vincristine and prednisone. Because of the progressive nature of her symptoms, a brain biopsy was performed and revealed neurotubular dissociation, which, in experimental animal models, is characteristic of vincristine toxicity. All other causes of encephalopathy have been ruled out. The drug was withheld and the clinical symptoms and findings resolved. The occurrence of unusual and severe neurologic side effects during the course of conventional induction therapy for childhood ALL warrants careful evaluation for evidence of vincristine toxicity.

Inhibition of human lymphocyte cyclic nucleotide phosphodiesterases by the chlorinated adenosine analog DTA-35

Human (E+)-T-lymphocytes have multiple cyclic nucleotide phosphodiesterase activities, some of which are markedly inhibited by the chlorinated adenosine derivative 9-(3',5'-dichloro-2',3',5'-trideoxy-beta-D-threo-pentofuranosyl)adenine (DTA-35).

Femoropopliteal bypass using externally supported polytetrafluoroethylene grafts. Early results in a multiinstitutional study

A multiinstitutional retrospective study was undertaken to evaluate the externally supported PTFE graft to determine whether a nonkinking, noncompressible graft offers advantages in patency and limb salvage. We studied the results of 104 femoropopliteal arterial reconstructions performed on 99 patients between June 1981 and June 1983. The combined above-the-knee and below-the-knee cumulative patency rate at 2 years was 88 percent and the limb salvage rate was 97 percent. We found these results to be comparable to the patency typical of saphenous vein grafts and better than that of reinforced PTFE grafts. The improved patency is due to the lack of kinking and compressibility of the externally supported PTFE graft, as well as histologic evidence of excellent collagen infiltration which stabilizes the graft in position. A longer follow-up period is certainly needed to make definite recommendations, but our preliminary studies are encouraging.

Phosphodiesterase-probes show distinct defects in rd mice and Irish setter dog disorders

The phosphodiesterase from the visual cells of rd mice and affected Irish setter dogs has been analyzed, using biochemical, biophysical, and immunological techniques. The authors' findings demonstrate that the mechanisms that cause a deficiency in phosphodiesterase activity in rd mice and Irish setter dogs are distinctly different. Apparently, the phosphodiesterase complex is normal in affected Irish setter dogs but is abnormal in rd mice. The criteria used for determining the normalcy of the phosphodiesterase complex were sedimentation characteristics, immuno-cross-reactivity, and histone-activation, which is shown to be a unique characteristic of the visual cell enzyme. According to these criteria, the phosphodiesterase complex in the visual cells of rd mice is either absent or abnormal from the onset of visual cell differentiation until degeneration, because it exhibits no cross-reactivity with antibody to phosphodiesterase; it is not activated by histone; and if present, it exhibits abnormal sedimentation characteristics and perhaps subunit structure. On the other hand, phosphodiesterase from the visual cells of affected Irish setter dogs is normal by the same criteria, because it cross-reacts with antibody against phosphodiesterase; it is activated by histone; and it exhibits normal sedimentation and electrophoretic patterns. It is proposed that depressed levels of phosphodiesterase activity in affected setter photoreceptors are due, perhaps, to a defect in the light-initiated cascade which activates the enzyme normally, in situ.

cGMP phosphodiesterase in rod and cone outer segments of the retina

Immunochemical, chromatographic, and sodium dodecyl sulfate gel electrophoresis studies suggest that immunologically related but distinct cyclic GMP phosphodiesterases are present in rod and cone outer segments of the retina. Immunocytochemical studies demonstrated that one monoclonal antibody (ROS-1) recognized a determinant present in both rod and cone outer segments, while another monoclonal antibody (ROS-2) only recognized rod outer segments. At least two peaks of phosphodiesterase activity could be separated by high-performance anion-exchange chromatography of retinal extracts. Both peaks were recognized by ROS-1. None of the first peak and only 80% of the second broad peak of activity were recognized by ROS-2. High-performance liquid chromatography profiles from human fovea and several other types of cone-enriched retina showed that most of the activity was contained in the first peak, suggesting that this activity was derived from cone outer segments. Conversely, the phosphodiesterase in rod-enriched preparations migrated predominately in the second peak. Sodium dodecyl sulfate-gel electrophoresis indicated that this first peak contained a single large immunoreactive polypeptide (alpha') that migrated with the same mobility as a phosphorylase b standard and was distinct from the more rapidly migrating large immunoreactive polypeptides (alpha and beta) present in a broad second peak. The second peak could be further separated into a first part that contained a doublet of two immunoreactive polypeptides (alpha and beta) that migrated faster than phosphorylase b and a later part that contained only the most rapidly migrating polypeptide (beta). All of the peaks could be activated by histone or transducin:GTP, implying that all contained a small 11-kDa inhibitory subunit (gamma) of the enzyme. Since the larger (alpha') and smaller (beta) immunoreactive polypeptides could be completely separated from the alpha polypeptide and from each other, yet still retain the ability to be activated by histone or transducin, the data suggest that only a single species of polypeptide-inhibitor complex (e.g. alpha' gamma, alpha gamma, or beta gamma) was required for histone or transducin:GTP activation.

Immunologic characterization of the photoreceptor outer segment cyclic GMP phosphodiesterase

High affinity (KD approximately 1 X 10(-9) M) monoclonal antibodies (ROS-1 and ROS-2) were prepared to bovine photoreceptor outer segment cGMP phosphodiesterase. ROS-1 immunoadsorbed greater than 95% of the cGMP phosphodiesterase activity from a detergent-solubilized bovine retina extract while ROS-2 immunoadsorbed only a subfraction of the same activity. Sodium dodecyl sulfate gel analysis of these immunoadsorbates demonstrated that ROS-1 and ROS-2 specifically adsorbed only peptides that comigrated with purified rod outer segment phosphodiesterase. Limited trypsin digestion of purified rod outer segment phosphodiesterase greatly reduced its affinity for ROS-1 but not ROS-2. When a crude heat-stable inhibitor fraction was added back to the activated enzyme, the affinity for ROS-1 was restored, suggesting that the inhibitor was necessary for ROS-1 binding. ROS-1 but not ROS-2 was found to inhibit cGMP phosphodiesterase which had been activated either by dilution or guanyl nucleotide. The inhibitory property of ROS-1 may provide a useful probe for directly studying the effects of this phosphodiesterase on the phototransduction response in the retina. Sodium dodecyl sulfate gel analysis demonstrated that the ROS-1 immunoadsorbates from mammals, fish, and amphibia contained peptides of similar mobility. Immunocytochemistry performed with ROS-1 and fluorescein isothiocyanate-conjugated rabbit anti-mouse IgG localized the antigenic determinant to both rod and cone outer segments suggesting the presence of an antigenically similar phosphodiesterase in both types of photoreceptors.

Employment following peripheral vascular surgery: an increasingly critical issue

As discussion for decreasing social security benefits or increasing the age of retirement ensues, the effectiveness of maintaining patients' employment following vascular surgery becomes extremely important. Two hundred fifty-five major vascular operations were performed from 1977 to 1981 on an employed populace. There was a 64% incidence of return to full employment following a major vascular procedure. The ability to return to work was statistically related to the degree of success of surgery following carotid endarterectomy, aortofemoral bypass for occlusive disease, femoral-distal and femoropopliteal bypass. The ability to work following abdominal aortic aneurysm resection, however, was statistically related to the age of the patient, not the outcome of the operation. Seventy-five percent of patients whose operative indication for aortofemoral and femoropopliteal bypass was claudication returned to work. Only 3% of patients who had been receiving disability benefits for vascular disease prior to vascular reconstruction returned to work. There was no correlation with the success of the operation or the age of the patient. One of the goals involved in performing vascular surgery is to return the patient to full employment. It is encouraging to see that this goal is achieved.

Experience with subclavian vein for vascular access

We report our experience with the subclavian vein as a route for temporary vascular access. By modifying the technique described by Uldall one can place these catheters at the bedside without the need of a separate exit tunnel. They are easily maintained in place and allow for early discharge home while awaiting permanent vascular access maturation. The results of approximately 600 dialysis treatments showed adequate clearence with a mean postdialysis drop in creatinine of 5.0mg./dl. and BUN of 46mg./dl. Complication rates were minimal with no hemo or pneumothorax. The rate of complications between bedside and operating room placement was not different. We feel the low complication rate, the ease of insertion, and the patency at home makes this an attractive alternative to other means of temporary dialysis such as: peritoneal dialysis, repeat femoral vein catheterization or arteriovenous shunts.

Elimination of platelets from mononuclear cell preparations using heat-killed yeast

A new method for reducing platelet contamination in mononuclear cell preparations using heat killed yeast is presented. Yeast cells are added to the buffy coat of peripheral blood, incubated at 37 degrees C for 1 hour, layered over a Ficoll-Hypaque gradient, and centrifuged at 700 g for 30 minutes at room temperature. The cells at the interface are collected and evaluated for platelet count, lymphocyte surface markers, and mononuclear cell recovery. With increasing yeast concentration, the platelet count decreases to 93% over control values. No detectable lymphocyte subset is removed by this method. Cell recovery varies, but seems to decrease with the addition of higher concentrations of yeast cells. Normal plasma is required for the successful removal of platelets. Heat-inactivated plasma significantly reduces the efficiency of platelet removal.

Oral contraceptives and gastrointestinal disorders

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