Photon-Induced Quantum Oscillations of the Terahertz Conductivity in Graphene.

In this work, we present a theory that is able to explain the nonmonotonic decreasing behavior (observed in experimental data1-12) of the graphene terahertz conductivity with the increase of the field frequency. In this connection, the displacement of the structure of topological states inside the energy band gap, which appears in graphene due to the strong photon-electron coupling, and the narrowing of this gap, as result of electron transitions from bound photon-dressed electron states to extended states outside the energy gap driven by the field frequency, lead to a periodic change of singularities near the edge of the band gap, resulting in subtle quantum oscillations of the dynamical terahertz conductivity. This quantum contribution complements the Drude response, which fits the spectral range. On the other hand, the scattering processes by impurities favor interband transitions, suppressing this way intraband terahertz absorptions, which are related to optical transitions from inside to outside the gap.

In vivo stimulation of platelet production in a primate model using IL-1 and IL-3.

The in vivo administration of various cytokines for hematopoietic stimulation has led primarily to the enhancement of the myeloid response with an insignificant contribution toward stimulating any increase in platelet production. Current studies have suggested that interleukin 1 (IL-1) and interleukin 3 (IL-3) are two of several factors that have an effect on either megakaryocyte formation or platelet production. The objective of our research was to investigate how the in vivo administration of IL-1 or IL-3 or a combination could be used to regulate megakaryocytopoiesis and platelet production in nonhuman primates. A single dose of IL-1 was able to stimulate an increase in platelet production for 3 weeks. The response was shown to be biphasic, with increased platelet counts of 46% and 49% above baseline on days 8 and 17, respectively. In contrast, the administration of IL-3 for 6 days led to an increase of 29% above baseline on day 17. An interesting observation was that the increased platelet counts were accompanied by a transient increase in the peripheral blood of a highly proliferative megakaryocyte colony-forming cell (MK-CFC), which attained a maximum concentration on day 7. The administration of a sequential combination of IL-1, then IL-3, was further evaluated to elucidate a possible potentiation on platelet production. The result was a similar increase in platelets to that observed in IL-1-only-treated monkeys for the first 7 days. However, the most significant effect was observed on day 17, when the 85% increase in platelets was demonstrated to be additive of the single-agent effects on that day. A reversal in the order of cytokine administration did not affect platelet production in this manner. In IL-1, then IL-3-treated monkeys, the increased platelet counts were also accompanied by an increase in the concentration of the peripheral blood MK-CFC from days 7 through 14. These results demonstrate that a combination of factors may be required to enhance platelet production, stimulating not only the formation of megakaryocytes but also stimulating the production and release of platelets into the peripheral blood.

Recovery from severe hematopoietic suppression using recombinant human granulocyte-macrophage colony-stimulating factor.

The ability of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) to enhance recovery of a radiation-suppressed hematopoietic system was evaluated in a nonuniform radiation exposure model using the rhesus monkey. Recombinant human GM-CSF treatment for 7 days after a lethal, nonuniform radiation exposure of 800 cGy was sufficient to enhance hematopoietic reconstitution, leading to an earlier recovery. Monkeys were treated with 72,000 U/kg/day of rhGM-CSF delivered continuously through an Alzet miniosmotic pump implanted subcutaneously on day 3. Treated monkeys demonstrated effective granulocyte and platelet levels in the peripheral blood, 4 and 7 days earlier, respectively, than control monkeys. Granulocyte-macrophage colony-forming unit (CFU-GM) activity in the bone marrow was monitored to evaluate the effect of rhGM-CSF on marrow recovery. Treatment with rhGM-CSF led to an early recovery of CFU-GM activity suggesting that rhGM-CSF acted on an earlier stem cell population to generate CFU-GM. Thus, the effect of rhGM-CSF on hematopoietic regeneration, granulocyte recovery, and platelet recovery are evaluated in this paper.

The rhesus monkey: a primate model for hemopoietic stem cell studies.

Two heterogeneous cell populations (CP 1-7 and CP 8-10) were separated from rhesus monkey bone marrow using counterflow centrifugation-elutriation (CCE). These two cell populations were distinct with respect to morphological composition, expression of cell surface antigens, hemopoietic progenitor cell activity, and concentration of hemopoietic stem cells (HSC). The hemopoietic progenitor cell activity and HSC were concentrated in CP 8-10. In autologous transplantation studies, CP 8-10 reconstituted the lymphohemopoietic system of lethally irradiated monkeys in a manner similar to that of monkeys transplanted with unfractionated bone marrow cells. CP 1-7 was lymphocyte rich and depleted of progenitor cell activity. Transplantation of CP 1-7 led to eventual lymphohemopoietic reconstitution of irradiated monkeys; however, complete engraftment was delayed by as much as 14 days compared to either the transplantation of CP 8-10 or to unfractionated bone marrow. Thus, a presence of the HSC in the lymphocyte-rich progenitor-cell-depleted population can be detected in the rhesus model.

Countercurrent centrifugal elutriation (CCE) recovery profiles of hematopoietic stem cells in marrow from normal and 5-FU-treated mice.

Data presented in this report describe countercurrent centrifugal elutriation (CCE) recovery profiles of hematopoietic colony-forming cells (CFC) in marrow from normal and 5-fluorouracil-(5-FU) treated mice. Of the total nucleated cells, 75%-95% were recovered, and up to 80% of CFC were recovered after CCE of bone marrow from normal mice. Red blood cells and the majority of lymphocytes were collected in fractions well separated from the CFC. In addition, the CCE recovery profiles of populations of CFC (i.e., BFU-E, CFU-E, GM-CFC, and HPP-CFC) were distinct. The distribution of recovered day 8 CFU-S was different from the distribution of day 12 CFU-S. The CCE recovery profiles of CFC in regenerating marrow from 5-FU-treated mice were shifted to fractions of larger cells, presumably in cell cycle. These data demonstrate that CCE is useful as a method of further characterizing qualitative and quantitative changes in populations of CFC occurring after various hematopoietic-influencing regimens.

Anti-Gal(alpha)1-3Gal antibody response to porcine bone marrow in unmodified baboons and baboons conditioned for tolerance induction.

BACKGROUND: Mixed lymphohematopoietic chimerism can provide an effective means of inducing longterm immunological tolerance and has been documented in a monkey allograft model. A conditioning regimen including nonmyeloablative or myeloablative irradiation and splenectomy has been used to induce chimerism in a pig-to-primate transplantation model. Since the presence of anti-Gal(alpha)1-3Gal (alphaGal) natural antibodies leads to the hyperacute rejection of pig organs transplanted into primates, extracorporeal immunoaffinity adsorption (EIA) of anti-alphaGal antibodies is also included in the regimen. The effect of the tolerance induction protocol on the anti-alphaGal antibody response has been assessed. METHODS: Anti-alphaGal antibody was measured after the EIA of plasma through an alphaGal immunoaffinity column in baseline studies involving two unmodified baboons, one splenectomized baboon, and one baboon that received a challenge with porcine bone marrow (BM), and in three groups of baboons (n=2 in each group) that received different conditioning regimens for tolerance induction. Group 1 received a nonmyeloablative conditioning regimen without porcine BM transplantation. Group 2 received nonmyeloablative conditioning with pig BM transplantation and pig cytokine therapy. Group 3 received myeloablative conditioning, an autologous BM transplant (with BM depleted of CD2+ or CD2+/CD20+ cells), and pig BM transplantation. RESULTS: In the baseline studies, a single EIA of anti-alphaGal antibodies in an unmodified animal initially depleted anti-alphaGal antibody, followed by a mild rebound. Nonmyeloablative conditioning (group 1) in the absence of pig cell exposure reduced the rate of anti-alphaGal antibody return. Pig BM cells markedly stimulated anti-alphaGal antibody production in an unmodified baboon (alphaGal IgM and IgG levels increased 40- and 220-fold, respectively). This response was significantly reduced (to an only 2- to 5.5-fold increase of IgM and IgG) in baboons undergoing nonmyeloablative conditioning (group 2). A myeloablative conditioning regimen (group 3) prevented the antibody response to pig BM, with the reduction in response being greater in the baboon that received autologous BM depleted of both CD2+ and CD20+ cells. No new antibody directed against pig non-aGal antigens was detected in any baboon during the 1 month follow-up period. CONCLUSIONS: (i) EIA of anti-alphaGal antibody in unmodified baboons results in a transient depletion followed by a mild rebound of antibody; (ii) exposure to pig BM cells results in a substantial increase in anti-alphaGal antibody production; (iii) a nonmyeloablative conditioning regimen reduces the rate of antibody return and (iv) markedly reduces the response to pig BM cells; (v) the anti-alphaGal response is completely suppressed by a myeloablative regimen if CD2+ and CD20+ cells are eliminated from the autologous BM inoculum. Furthermore, (vi) challenge with pig BM cells appears to stimulate only an anti-alphaGal antibody response without the development of other (non-alphaGal) anti-pig antibodies. We conclude that regimens used for T-cell tolerance induction can be beneficial in reducing the anti-alphaGal antibody response to porcine BM.

Mixed allogeneic chimerism and renal allograft tolerance in cynomolgus monkeys.

We have developed a nonmyeloablative preparative regimen that can produce mixed chimerism and renal allograft tolerance between MHC-disparate nonhuman primates. The basic regimen includes ATG, nonmyeloablative total-body irradiation (TBI, 300 rads), thymic irradiation (TI, 700 rads), and donor bone marrow infusion. Kidney allografts from MHC-mismatched donors were transplanted with various manipulations of the preparative regimen. Monkeys treated with the basic regimen alone (n = 2) rejected allografts by day 15. With the addition of cyclosporine (CsA) for one month (n = 3), one monkey developed multilineage mixed chimerism and renal allograft tolerance thereafter (> 430 days). To reduce the toxicity of the preparative regimen, TBI was fractionated to 150 rads on two successive days in subsequent studies. All monkeys receiving this modified regimen (n = 4) developed multilineage chimerism with fewer side effects and accepted renal allografts long-term with no further immunosuppression (196 days, 198 days, > 150 days, and > 40 days). In long-term survivors, donor-specific nonreactivity was confirmed by MLR and skin transplantation. Three monkeys treated with the basic regimen plus CsA but with only 150 rads of TBI (n = 1) or no TBI (n = 2) did not develop multilineage chimerism and grafts were rejected (day 40-50) soon after the CsA discontinuation. Monkeys treated with the same regimen, but without DBM (n = 2), rejected kidney allografts by day 52. Therefore, at least transient engraftment of DBM appears to be essential for induction of donor specific tolerance in this monkey model.

Removal of anti-porcine natural antibodies from human and nonhuman primate plasma in vitro and in vivo by a Galalpha1-3Galbeta1-4betaGlc-X immunoaffinity column.

BACKGROUND: Natural antibodies (NAbs) against a terminal alpha1-3 galactosyl (alphaGal) epitope have been identified as the major human anti-pig NAbs. METHODS AND RESULTS: We used two synthetic alphaGal trisaccharides--type 6 (alphaGal6) and type 2(alphaGal2)--linked to an inert matrix to remove NAbs from human plasma in vitro. Flow cytometry indicated that an average of 85% of the NAb binding activity was depleted by adsorption with alphaGal6. By measuring the binding of NAbs to pig peripheral blood mononuclear cells and bone marrow cells, we demonstrated that alphaGal6 was more effective than alphaGal2 in removing NAbs, and the combination of alphaGal6 + alphaGal2 did not further increase removal of NAbs. The specificity of the removal of NAbs (IgM and IgG) reactive with the alphaGal epitope by alphaGal6 matrix was shown by enzyme-linked immunosorbent assay. In vivo studies in nonhuman primates compared plasma perfusion through a alphaGal6 immunoaffinity column with hemoperfusion through a pig liver for changes in blood pressure, hematocrit, platelets, and NAb adsorption. CONCLUSIONS: Both methods reduced the level of anti-pig IgM and IgG xenoreactive antibodies to nearly background, but column perfusion caused less hypotension and reduction in platelets than liver perfusion. Four pig kidneys transplanted into monkeys after column perfusion did not undergo hyperacute rejection, remaining functional for 2-10 days, with a mean functional period of 7 days, demonstrating that a pig kidney can support renal function in a primate.

Long-term discordant xenogeneic (porcine-to-primate) bone marrow engraftment in a monkey treated with porcine-specific growth factors.

BACKGROUND: Mixed allogeneic hematopoietic chimerism has previously been reliably achieved and shown to induce tolerance to fully MHC-mismatched allografts in mice and monkeys. However, the establishment of hematopoietic chimerism has been difficult to achieve in the discordant pig-to-primate xenogeneic model. METHODS: To address this issue, two cynomolgus monkeys were conditioned by whole body irradiation (total dose 300 cGy) 6 and 5 days before the infusion of pig bone marrow (BM). Monkey anti-pig natural antibodies were immunoadsorbed by extracorporeal perfusion of monkey blood through a pig liver, immediately before the intravenous infusion of porcine BM (day 0). Cyclosporine was administered for 4 weeks and 15-deoxyspergualin for 2 weeks. One monkey received recombinant pig cytokines (stem cell factor and interleukin 3) for 2 weeks, whereas the other received only saline as a control. RESULTS: Both monkeys recovered from pancytopenia within 4 weeks of whole body irradiation. Anti-pig IgM and IgG antibodies were successfully depleted by the liver perfusion but returned to pretreatment levels within 12-14 days. Methylcellulose colony assays at days 180 and 300 revealed that about 2% of the myeloid progenitors in the BM of the cytokine-treated recipient were of pig origin, whereas no chimerism was detected in the BM of the untreated control monkey at similar times. The chimeric animal was less responsive by mixed lymphocyte reaction to pig-specific stimulators than the control monkey and significantly hyporesponsive when compared with a monkey that had rejected a porcine kidney transplant. CONCLUSION: To our knowledge, this is the first report of long-term survival of discordant xenogeneic BM in a primate recipient.

Porcine kidney and heart transplantation in baboons undergoing a tolerance induction regimen and antibody adsorption.

BACKGROUND: Xenotransplantation would provide a solution to the current shortage of organs for transplantation. Our group has been successful in inducing tolerance in mice and monkey models of allogeneic transplantation. The present study attempts to extend the same tolerance-inducing regimen to a pig-to-baboon organ transplantation model. METHODS: Nine baboons underwent a conditioning regimen (consisting of nonmyeloablative or myeloablative whole body and thymic irradiation, splenectomy, antithymocyte globulin, pharmacologic immunosuppression and porcine bone marrow transplantation [BMTx]), which has previously been demonstrated to induce donor-specific allograft tolerance in monkeys. In addition, immunoadsorption of anti-alphaGal antibody (Ab) was performed. Four of the nine baboons received pig kidney transplants (KTx), and one also underwent repeat transplantation with an SLA-matched kidney. Two received heterotopic pig heart transplants (HTx). Three baboons underwent conditioning without organ transplantation for long-term studies of natural Ab kinetics. RESULTS: In the three baboons that received the conditioning regimen without an organ transplant, immunoadsorption reduced Ab by approximately 90%, but recovery of Ab to pretreatment level or higher occurred within 7 days. In contrast, the level of Ab remained low after organ transplant. No Ab to pig antigens other than alphaGal was detected in any baboon before or after BMTx, KTx, or HTx. No graft succumbed to hyperacute rejection. KTx function began to deteriorate within 3-6 days, with oliguria and hematuria progressing to anuria, and the kidneys were excised after 3, 6, 9, 11, and 14 days, respectively. One HTx ceased functioning at 8 days; the second baboon died with a contracting HTx at 15 days. Features of coagulopathy and thrombocytopenia developed in all six transplanted baboons (high D-dimer, prolonged prothrombin time and partial thromboplastin time, and falling fibrinogen) resulting in serious bleeding complications in two baboons, one of which died on day 9. Donor organs showed progressive acute humoral rejection with deposits of IgM, IgG, and complement; a focal mononuclear cellular infiltrate was also observed. The ureter was the earliest structure of the KTx affected by rejection, with progression to necrosis. CONCLUSIONS: This conditioning regimen prevented hyperacute rejection but was ineffective in preventing the return of Ab, which was associated with the development of acute humoral rejection with features of coagulopathy. No baboon developed anti-pig Ab other than alphaGal Ab. Further modifications of the protocol directed toward suppression of production of Ab are required to successfully induce tolerance to pig organs in baboons.

Transfer of swine major histocompatibility complex class II genes into autologous bone marrow cells of baboons for the induction of tolerance across xenogeneic barriers.

BACKGROUND: The present study examined the potential role of gene therapy in the induction of tolerance to anti-porcine major histocompatibility complex (SLA) class II-mediated responses after porcine renal or skin xenografts. METHODS: Baboons were treated with a non-myeloablative or a myeloablative preparative regimen before bone marrow transplantation with autologous bone marrow cells retrovirally transduced to express both SLA class II DR and neomycin phosphotransferase (NeoR) genes, or the NeoR gene alone. Four months or more after bone marrow transplantation, the immunological response to a porcine kidney or skin xenograft was examined. Both the renal and skin xenografts were SLA DR-matched to the transgene, and recipients were conditioned by combinations of complement inhibitors, adsorption of natural antibodies, immunosuppressive therapy, and splenectomy. RESULTS: Although the long-term presence of the SLA transgene was detected in the peripheral blood and/or bone marrow cells of all baboons, the transcription of the transgene was transient. Autopsy tissues were available from one animal and demonstrated expression of the SLA DR transgene in lymphohematopoietic tissues. After kidney and skin transplantation, xenografts were rejected after 8-22 days. Long-term follow-up of control animals demonstrated that high levels of induced IgG antibodies to new non-alphaGal epitopes developed after organ rejection. In contrast, induced non-alphaGal IgG antibody responses were minimal in the SLA DR-transduced baboons. CONCLUSIONS: Transfer and expression of xenogeneic class II DR transgenes can be achieved in baboons. This therapy may prevent late T cell-dependent responses to porcine xenografts, which include induced non-alphaGal IgG antibody responses.

Biocompatibility of lipid microcylinders: effect on cell growth and antigen presentation in culture.

The authors are developing a lipid-based microcylinder for the controlled release of biological response modifiers and as templates for cellular migration and differentiation. These structures are comprised of a photopolymerizable phosphatidylcholine (1,2-ditricosa-10,12-diynoyl-sn-glycero-3-phosphocholine) and form spontaneously as a result of a thermotropic phase transition in aqueous solution or in a cosolvent solution of 70:30 ethanol:water. The hollow cylinders are helically wrapped lipid bilayers, variable in length (50-250 microns, depending on conditions of formation) and are 0.5-1.0 microns in diameter. The interaction has been examined of three types of lipid microcylinders: (1) monomeric, (2) photopolymerized by exposure to 254 nm light, and (3) surface-modified by incorporation of 6 mol% gangliosides, with different human cell lines and peripheral blood leucocytes to evaluate the biocompatibility of these structures. The proliferative status of U937 (a histiocytic monocyte), K562 (an erythroleukaemic cell), and Jurkat's derivative (a T-lymphoblast) as measured by pulsed tritiated thymidine was unaffected by the presence of up to 100 micrograms/ml of lipid microcylinders after 3 d in culture. Adherent human peripheral blood monocytes were shown to form adhesive contacts with the lipid microcylinders. An 'association' index from this interaction shows that after 3 d in culture, the association was much lower for those microcylinders that had incorporated ganglioside compared with monomeric or polymerized structures. The lipid microcylinders do not activate T-cells isolated from human peripheral blood, nor do they inhibit the activation of T-cells by phorbol esters or other mitogens.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved survival of dogs exposed to fission neutron irradiation and transplanted with DLA identical bone marrow.

The survival of dogs exposed to fission neutron irradiation, a component in the radiation dose of reactor accidents, was improved by the administration of DLA-identical allogeneic bone marrow but not by the administration of DLA-mismatched allogeneic bone marrow. The level of survival observed at 2.55 Gy was similar to that observed after autologous bone marrow transplantation. The transplanted allogeneic bone marrow, however, survived for only 2-3 weeks, but provided enough mature peripheral blood cells during this time to endure the initial radiation insult. Subsequent recovery of autologous bone marrow led to the ultimate survival of the dogs. Additional radiation protocols were evaluated in order to obtain permanent engraftment of the donor marrow cells. A higher neutron dose or a second radiation of 6.0 Gy gamma rays led to severe damage of the gastrointestinal tract and an early death. A third regimen, a second radiation dose of 4.0 Gy of gamma rays, led to permanent engraftment in one dog but its survival was complicated by graft-versus-host disease.

The relative biological effectiveness of mixed fission-neutron-gamma radiation on the hematopoietic syndrome in the canine: effect of therapy on survival.

Acute lethality syndromes produced by the accidental exposure of humans to mixed neutron and gamma radiation from external sources can be related to acute lethality from photon irradiation using the relative biological effectiveness (RBE) for common end points. We used the canine as a model to study injury following exposure to mixed neutron and gamma radiation from the AFRRI TRIGA reactor. Exposures from the reactor were steady-state mode (40 cGy/min, bilateral) with an average neutron energy of 0.85 MeV; tissue-air ratio = 0.59 at midline abdominal. Healthy male and female canines were irradiated free-in-air behind a 6-in. lead wall; the neutron-gamma ratio was 5.4:1 at the entrance skin surface; exposures are reported as midline tissue doses. Bilateral exposure resulted in an LD50/30 of 153 cGy without therapeutic clinical support. Addition of clinical support consisting of fluids, antibiotics, and fresh irradiated platelets/whole blood increased the bilateral LD50/30 to 185 cGy, a dose modifying factor (DMF) of 1.21. This corresponds to respective LD50/30 values for bilateral 60Co gamma exposures of 260 and 338 cGy for nonsupported and clinically supported animals, and a DMF of 1.30. The RBE based on the values determined at midline tissue is approximately 1.69. Clinical support after bilateral irradiation produced a similar DMF to those of mixed fission neutrons and gamma rays and 60Co gamma rays alone. The RBE of 1.69 for midline tissue bilateral exposures is higher than 1, an RBE often cited for large animals. Therapeutic support administered to lethally irradiated canines significantly improved survival and increased the LD50/30 independent of radiation quality.

Pig to monkey bone marrow and kidney xenotransplantation.

BACKGROUND: The intensity of discordant xenograft cellular rejection makes it unlikely that safe doses of immunosuppressive drugs will alone be sufficient to permit long-term survival. We have therefore concentrated our efforts on establishing tolerance to xenogeneic organs through lymphohematopoietic chimerism and the elimination of preformed natural antibodies (nAbs). METHODS: Here we report the most recent series of 11 technically successful porcine to nonhuman primate transplantation procedures. In eight experimental animals induction therapy consisted of (1) 3 x 100 cGy nonlethal whole body irradiation (day -6 and day -5) to all animals, (2) horse anti-human thymocyte globulin (day -2, day -1, and day 0) to seven of the animals, (3) 700 cGy thymic irradiation (day -1) to five of the animals, and (4) pig bone marrow infused on day 0 (2-9 x 10(8)/cells/kg). On day 0, just before the renal xenograft, the recipient was splenectomized, and antipig nAbs were removed by means of perfusion of the monkey's blood through either a pig liver (n = 6) or a Gal-alpha (1,3)-Gal adsorption column (n = 5). There control animals did not receive this pretransplantation induction therapy but did undergo hemoperfusion and posttransplantation immunosuppression identical to the experimental animals. All 11 recipients were treated after transplantation with cyclosporin A and 15-deoxyspergualin. Recombinant pig-specific growth factors (interleukin-3 and stem cell factor) were given to six experimental animals from day 0 until the termination of the experiment. RESULTS: Analysis of recipients' sera by means of flow cytometry indicated the effective removal of immunoglobulin M and immunoglobulin G nAbs by either liver perfusion or column adsorption. In the eight experimental animals, nAb titers remained low until death (up to 15 days), but in the three control animals nAb titers increased substantially with time. The longest surviving recipient maintained excellent kidney function with creatinine levels at 0.8 to 1.3 mg/dl throughout its course. Death occurred at day 15 from complications caused by a urinary leak and pancytopenia. Histologic examination of the xenograft revealed only focal tubular necrosis and cytoplasmic vacuolization, with trace amounts of fibrin and C3 in peritubular capillaries. In this animal a fraction of the peripheral blood cells (3%) at day 7 were of pig origin as detected by pig-specific monoclonal antibodies. In addition, colony-forming assays performed on a bone marrow biopsy specimen taken at day 14 indicated that approximately 30% of the relatively few myeloid progenitors detected were of swine origin. CONCLUSIONS: We have demonstrated that our protocol is effective in the prevention of hyperacute rejection and in the maintenance of excellent function of the renal xenograft for up to 15 days. These results also indicate that at least short-term engraftment of the xenogeneic donor bone marrow cells is possible to achieve in this discordant large animal combination. Longer survivals will be required to assess the possible effect of this engraftment on induction of tolerance.

Therapeutic use of recombinant human G-CSF (rhG-CSF) in a canine model of sublethal and lethal whole-body irradiation.

The short biologic half-life of the peripheral neutrophil (PMN) requires an active granulopoietic response to replenish functional PMNs and to maintain a competent host defence in irradiated animals. Recombinant human G-CSF (rhG-CSF) was studied for its ability to modulate haemopoiesis in normal dogs as well as to decrease therapeutically the severity and duration of neutropenia in sublethally and lethally irradiated dogs. For the normal dog, subcutaneous administration of rhG-CSF induced neutrophilia within hours after the first injection; total PMNs continued to increase (with plateau phases) to mean peak values of 1000 per cent of baseline at the end of the treatment period (12-14 days). Bone-marrow-derived granulocyte-macrophage colony-forming cells (GM-CFC) increased significantly during treatment. For a sublethal 200 cGy dose, treatment with rhG-CSF for 14 consecutive days decreased the severity and shortened the duration of neutropenia and thrombocytopenia. The radiation-induced lethality of 60 per cent after a dose of 350 cGy was associated with marrow-derived GM-CFC survival of 1 per cent. Treatment with rhG-CSF markedly reduced the lethality associated with exposure to 350 cGy of radiation to zero. White blood cell (WBC) and platelet recovery kinetics were correlated with degree of marrow damage. The rhG-CSF reduced the severity and duration of neutropenia. Control animals required antibiotic therapy (WBC less than 1000 mm3) for a total of 16 days versus 3 days for rhG-CSF-treated dogs. The duration of thrombocytopenia was reduced, although the severity of depletion was unchanged with treatment. These data indicate that in the lethally irradiated dog, effective cytokine therapy with rhG-CSF will increase survival through the induction of earlier recovery of neutrophils and platelets.

Granulocyte colony stimulating factor (G-CSF) for mustard-induced bone marrow suppression.

The authors describe the development of a clinical protocol to treat mustard gas-induced myelosuppression with granulocyte colony stimulating factor (G-CSF), a hematopoietic growth factor. Limited clinical evidence suggests a significant role for mustard gas-induced myelosuppression in the overall morbidity of mustard gas victims. Initial data from primates revealed that G-CSF could ameliorate neutropenia following nitrogen mustard exposure. Exploiting the extensive oncologic experience with G-CSF, which demonstrated its safety and absence of serious side effects the authors developed a clinical protocol for use of this drug in potential mustard gas victims in the Persian Gulf conflict.

[Control of oral anticoagulation. Current concepts]. / El control de la anticoagulación oral. Conceptos actuales.

The main objective of this short review is to bring into focus the most relevant of the recent advances in prothrombin time standardization and analyze the recommendations of the World Health Organization (WHO) for monitoring patients with thrombotic disorders under treatment with oral anticoagulant drugs. The prothrombin time (PT) is indicative of the proper therapeutic range in patients receiving oral anticoagulant drugs; however the reliability of the results will depend on the source and nature of the thromboplastin used. Different normal and therapeutic rangers are frequently observed when different brands of thromboplastin reagents and/or methods are used. The WHO, in conjunction with the International Committee of Thrombosis and Hemostasis and the International Committee of Standardization in Hematology, has recommended a calibration scheme for thromboplastin standardization with special reference for anticoagulant monitoring. Instead of reporting patient values, either in seconds or percent activity, WHO recommends the PT results in terms of an international normalized ratio (INR). This is obtained by formula: INR = RC in which R is the patient's PT and C is the international sensitivity index (ISI) of the thromboblastine employed. The INR represents the PT that would be obtained if it were performed with the WHO thromboplastin reference preparation. We suggest that these new concepts should be implemented by both laboratory and clinical professionals with the purpose of improving the effectiveness and safety of oral anticoagulation.

[Non-Hodgkin's lymphoma secondary to Hodgkin's disease treated with chemo- and radiotherapy. Report of a case]. / Linfoma no Hodgkin secundario a enfermedad de Hodgkin tratada con quimio- y radioterapias. Informe de un caso.

In 18 years of experience in the use of combined chemotherapy in Hodgkin's disease at the Instituto Nacional de la Nutrición Salvador Zubirán, the first case of non-Hodgkin's lymphoma secondary to Hodgkin's disease was identified. The patient was a 23 year old male who initially developed a nodular sclerosis type of Hodgkin's disease. Three years later, the biopsies showed lymphocyte predominance type of Hodgkin's disease. Finally, one year later, the patient developed a diffuse small cleaved cell lymphoma. Non-Hodgkin's lymphoma occurring in patients treated with combined chemotherapy and radiotherapy after Hodgkin's disease is a rare complication. We believe that the genesis of a second neoplasm in these cases may be due to both disturbances in the cellular immunity intrinsic to Hodgkin's disease and the treatment with combined chemotherapy and radiotherapy.

Long-term results of high-dose methylprednisolone in aplastic anemia.

Four males and two females, aged 13 to 57 years (median 22 years), with acquired severe aplastic anemia (AA) were treated with intravenous bolus of high doses of 6-methylprednisolone (MPL). Patients received MPL within a 30-day period at a dose of 20 mg/kg/day (3 days), 10 mg/kg/day (4 days), 5 mg/kg/day (4 days), 2 mg/kg/day (9 days), and 1 mg/kg/day (10 days). Within the first 3 months following MPL therapy, a response rate of 83%, assessed by means of increase in reticulocytes, neutrophils or platelets, was recorded in the group: two cases showed partial response and three improvement. The 3-month, and 1-, 2- and 3-year survival of the group was 67%, 50%, 33% and 33%, respectively. Neither the presence of reticulocytopenia or thrombocytopenia prior MPL therapy, nor age, gender, etiology of AA or time between diagnosis and initiation of MPL influenced survival. In contrast, neutrophil counts before MPL treatment had a strong prognostic value. Patients with less than 0.5 x 10(9)/L neutrophils had a median survival of 4.2 months (range 1.2 to 5.2 months) as compared to the 36.1 months median survival (range 12.1 to 36.8 months) of patients whose neutrophil counts were greater than 0.5 x 10(9)/L. Follow-up data suggest that the administration of androgens two months after MPL therapy did not modify survival. It is concluded that high-dose MPL is useful in the treatment of some patients with acquired severe AA, particularly in those with greater than 0.5 x 10(9)/L neutrophils who are not candidates for bone marrow transplantation.