Effects of recombinant human granulocyte colony-stimulating factor on neutrophil functions in aged animals

We have studied the effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on granulopoiesis and neutrophil functions in aged rats and aged mice. We subcutaneously injected rG-CSF or control vehicle into aged rats (22 months old and 25 months old) for 7 consecutive days, counted the peripheral neutrophils and evaluated the functions of neutrophils isolated from venous blood. The peripheral neutrophil count in aged rats tended to be increased as compared with that in young rats (11 weeks old). However, the neutrophils in aged rats exhibited a decline of superoxide anion (O2-) release and phagocytic activity as compared with young rats. The peripheral neutrophil count in aged rats was significantly increased 5-6-fold as many as the control value by rG-CSF treatment, which was accompanied by a significant enhancement of O2- release and of phagocytic activity being restored to normal levels or better. In another series of experiments, we subcutaneously injected rG-CSF or control vehicle into aged mice (24-28 months old) or young mice (8 weeks old) for 7 consecutive days, and evaluated the functions of neutrophils isolated from peritoneal cavity. The peritoneal exudate neutrophils from the aged mice exhibited a decline of phagocytic and chemotactic activity as compared with the young mice. These functions in both young and aged mice were significantly enhanced by rG-CSF-treatment, and these functions in rG-CSF-treated aged mice were restored to a level higher than the level in control young mice. These findings demonstrate that rG-CSF is capable of enhancing granulopoiesis and restoring the age-related decline of neutrophil functions.

[Vincristine played a pivotal role in hematological remission of thrombotic thrombocytopenic purpura (T.T.P.)]

A case of thrombotic thrombocytopenic purpura (TTP), in which vincristine (VCR) administration played a pivotal role in achieving the hematological remission, is presented. A 40-year-old woman with a chief complaint of purpura was transferred for detailed examination of thrombocytopenia. The presence of hemolytic anemia, schistocytosis, febrile clinical course, renal dysfunction and neurological abnormalities made the basis of a diagnosis of TTP. Twelve courses of consecutive plasma exchange and plasma infusion, which amounted to a total of 120l of fresh frozen plasma, were performed without obvious hematological improvement. Therefore, VCR (2 mg) was infused in addition to the plasma exchange. Three days later, platelets responded remarkably. After 10 days of hematological improvement, relapse occurred. VCR was reinfused. However, the second VCR infusion alone was not able to elevate platelets. With concomitant use of significant amounts of plasma, the platelet count responded gradually. Hematological remission was obtained and has continued until now. The exact role of VCR for TTP is still unknown; however, VCR is suggested to be effective for TTP as in the case presented here.

Cloning and sequence of a functionally active cDNA encoding the mouse ubiquitin-activating enzyme E1

A cDNA encoding the ubiquitin-activating enzyme, E1, was isolated from the mouse mammary carcinoma cell line, FM3A, and shown to complement mutant mouse cells deficient in the enzyme. The 3495-bp cDNA encodes 1058 amino acids (aa), and shares extensive homology with the human E1 enzyme at both the nucleotide and aa sequence levels.

[Clinical significance of urinary sediment dysmorphic red blood cells and casts in renal disease]

We investigated the utility of measuring dysmorphic red blood cells (d-RBC) and urinary casts in the diagnosis and assessment of prognosis of renal diseases by evaluating these parameters in a total of 278 urine specimens from 78 patients with various renal diseases at our hospital. Urinary sediments obtained by the conventional method with in 4 hours after voiding were subjected to Sternheimer and Malbin's staining and examined under a conventional light microscope. We used the criteria we previously devised for classification of RBC as d-RBC and for classification of casts hyaline, granular, epithelial, red blood cell, white blood cell, fatty, or waxy. When there were 5 or more urinary sediment red blood cells per high-power field, d-RBC was found in 94% of samples from patients with chronic glomerulonephritis. The finding of d-RBC was not related to glomerulonephritis pathologically diagnosed according to the WHO classification system for biopsy specimens. Even when there were fewer than 5 red blood cells per high-power field, d-RBC was sometimes found. Casts of all types were found in samples from patients with chronic glomerulonephritis or chronic renal failure. In samples from patients with chronic pyelonephritis, however, white blood cell, fatty, and waxy casts were not found, and less than 1 granular or epithelial cast per low-power field was found. The findings for the presence and the extent of both d-RBC and casts were in good accord with and changed with the clinical course, indicating that d-RBC and casts of urinary sediment can be used to predict the prognosis of patients with renal disease.

Experimentally produced fractures of articular cartilage and bone. The effects of shear forces on the pig knee

Experimental injuries of cartilage and bone were produced by applying shear force to the articular surfaces of the lateral femoral condyles of six-month-old pigs under various loading conditions. The lesions were divided into two groups, 'open' or 'closed', depending on the presence of a crack on the articular surface. Each was further divided into four types according to the depth of penetrating injury: (1) splitting of uncalcified cartilage; (2) splitting at the subchondral plate; (3) subchondral fracture; and (4) intra-articular fracture. When shear force was applied at high speed but with low energy, the articular cartilage surface was the first to crack. At low speed and low energy, splits occurred in the deeper layers first. As the energy increased, both loading conditions eventually resulted in similar open lesions. Experimentally produced shear injuries are useful models for clinical osteochondral fracture, osteochondritis dissecans, and chondromalacia patellae.

Effects of dichloroacetate on hemodynamic responses to dynamic exercise in dogs

To determine whether lactic acid production contributes significantly to the cardiac responses to muscular dynamic exercise, we administered intravenous sodium dichloroacetate (32 mumol.kg-1.min-1), a pyruvate dehydrogenase activator that facilitates lactate metabolism via the tricarboxylic cycle, in 12 dogs during two graded levels of treadmill exercise. Similar exercise was carried out in nine normal dogs receiving equimolar doses of NaCl. In the latter group, arterial lactate increased progressively from 0.80 +/- 0.11 (SE) mmol/l at rest to 2.13 +/- 0.28 mmol/l by the end of exercise. In contrast, arterial lactate did not change significantly (0.98 +/- 0.12 to 0.95 +/- 0.11 mmol/l) during exercise in dogs receiving dichloroacetate infusion. Dichloroacetate infusion also reduced the increases in plasma norepinephrine, heart rate, and left ventricular contractile indexes that occurred during exercise, suggesting that the sympathetic cardiac stimulation occurring during exercise may be related to the production of lactic acid. However, dichloroacetate affected neither the net increase in cardiac output nor the relationship between total body oxygen consumption and cardiac output that occurred during exercise. Thus we conclude that lactic acid production is not essential to the increase in cardiac output that occurs during mild-to-moderate exercise.

Plasma interleukin-6 levels in continuous ambulatory peritoneal dialysis and hemodialysis patients

Plasma levels of interleukin-6 (IL-6), a cytokine known to be involved in lymphocyte activation and in inflammation, were studied in 10 normal volunteers, 21 continuous ambulatory peritoneal dialysis (CAPD) patients and 41 hemodialysis patients. Plasma IL-6 levels in hemodialysis patients were significantly higher than those in normal volunteers and CAPD patients (p less than 0.05). The means of plasma IL-6 concentrations before and after hemodialysis did not change significantly. While IL-6 in peritoneal dialysate was detectable in only 3 of the 21 CAPD patients without peritonitis, it was extremely high in 2 patients with bacterial peritonitis. IL-6 levels decreased as peritonitis subsided.

Effects of recombinant human granulocyte colony-stimulating factor on neutrophil function in normal rats

We studied the effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on neutrophil functions in vitro using neutrophils isolated from the venous blood of normal rats. FMLP-induced superoxide anion (O2-) release, phagocytosis, and FMLP-induced chemotaxis were evaluated. These functions were significantly enhanced by rG-CSF treatment. In addition to performing neutrophil function assays, we evaluated FMLP binding to rat neutrophils after rG-CSF treatment. FMLP specific binding was not changed by rG-CSF treatment. In addition, we intravenously injected rG-CSF (10 micrograms/kg) or control vehicle into rats for 7 consecutive days, and evaluated the functions of neutrophils isolated from venous blood at 6 h after the final injection. The neutrophil count in the peripheral blood of rG-CSF-treated rats was increased significantly compared with that in control rats. FMLP-induced O2- release, phagocytosis, FMLP-induced chemotaxis and spontaneous migration of rG-CSF-treated neutrophils were significantly enhanced in comparison with those in control rats. These findings demonstrate that rG-CSF not only increases neutrophil counts in peripheral blood, but that it also enhances neutrophil functions, both in vitro and in vivo.

[Study on reconstruction of the anterior cruciate ligament in the monkey knee using polyester artificial ligament]

We performed an experimental study of ACL reconstruction utilizing polyester artificial ligament(Leeds-Keio). The quality of regenerated ligaments was compared between two different procedures; in the one 1 cm wide Leeds-Keio ligament was used alone for reconstruction(Group 1) and in the other, Leeds-Keio ligament of the same size was augmented with one-third width of free patellar tendon (Group 2). Eighteen knees of nine Japanese monkeys were used. The specimens were obtained at 2, 6 and 12 months after the operation and investigated macroscopically, microscopically and biomechanically. Regenerated ligaments in Groups 1 and 2 appeared identical and grossly normal. However, more mature and stable ligament was noted in the cylinder of artificial ligaments after 2 months after operation in Group 2 than in Group 1 in terms of both quality and quantity. Biomechanically, however, the maximum the tension in the regenerated ligaments was approximately 1/2-1/3 of that of normal ACL. The authors believe that more mature ligament was made in ACL reconstruction when the artificial ligament was augmented with autogenous soft tissue.

Electroviscosity of polyelectrolyte solutions

A theoretical expression for the electroviscous effect in polyelectrolyte solutions, caused by the distortion of counterion-distribution and counterion flow around a polyion under a velocity gradient of solvent flow, was obtained to elucidate the characteristic behaviour of the viscosity of highly charged polyelectrolyte solutions observed at low salt concentration. The derivation of the theory was performed on the basis of the Navier-Stokes-Onsager equation, Poisson equation, and diffusion equations for low molecular ions by the use of a cell model (free-volume model) for a polyion. Energy dissipation was obtained without directly solving these equations. It was found that the derived expression of viscosity explained the experimental results satisfactorily, and that the streaming potential effect caused by the counterion flow played an essential role in the increase in viscosity of polyelectrolyte solutions at finite polymer concentration and low salt concentration ranges.

Photolysis of 3-aryl-3-(trifluoromethyl)diazirines: a caveat regarding their use in photoaffinity probes

The photolysis of 3-(4-tolyl)-3-(trifluoromethyl)diazirine in the presence of benzene, methanol, carbon tetrachloride, cyclohexane, triethylsilane, or diethylamine led to photoproducts consistent with the intermediacy of a singlet carbene. In the case of diethylamine, the photoinsertion into the N-H bond of diethylamine produced the expected adduct, 1-(diethylamino)-2,2,2-trifluoro-1-(4-tolyl)ethane. However, the base-catalyzed elimination of hydrogen fluoride from this adduct afforded an enamine, alpha-(diethylamino)-beta,beta-difluoro-4-methylstyrene, and the subsequent hydrolysis of this enamine furnished diethylamine and 2,2-difluoro-1-(4-tolyl)ethanone. This elimination and hydrolysis sequence effectively reversed the photoinsertion process. A similar photoinsertion and hydrolysis process using 3-(4-n-octylphenyl)-3-(trifluoromethyl)diazirine also produced 2,2-difluoro-1-(4-n-octylphenyl)ethanone in modest yield. These results suggest that the photoinsertion products from 3-aryl-3-(trifluoromethyl)-diazirines in biological systems may suffer similar fates limiting, in part, their utility in obtaining primary sequence data.

Effects of short-term, diet-induced hypercholesterolemia on systemic hemodynamics, myocardial blood flow, and infarct size in awake dogs with acute myocardial infarction

BACKGROUND

Short-term cholesterol feeding has been shown to affect vasomotor tone and increase infarct size in anesthetized rabbits. The purpose of the study was to determine whether acute hypercholesterolemia reduced collateral flow to ischemic myocardium and increased infarct size in the awake dog.

METHODS AND RESULTS

Acute myocardial infarction was produced in awake dogs by a 4-hour left anterior descending coronary artery occlusion followed by 6-hour reperfusion after either a cholesterol-supplemented diet (n = 14) or a control diet of dog chow (n = 15) for 10 days. Infarct size was determined using nitroblue tetrazolium staining. In two subgroups, a 15-minute transient occlusion of the left anterior descending coronary artery was produced before the diet treatments and was compared with occlusion after diet treatments, so that the effects of hypercholesterolemia of collateral flow could be determined by paired comparisons. Cholesterol feeding increased plasma cholesterol to 288 +/- 52 mg/dl, which was twofold to threefold that in the control group (127 +/- 35 mg/dl), but had no effects on baseline systemic hemodynamics and myocardial blood flow. Coronary artery occlusion produced similar increases in heart rate, mean aortic pressure, left atrial pressure, and plasma norepinephrine in both groups of animals. However, cholesterol feeding reduced collateral flow to ischemic myocardium and increased infarct size, compared with the control group. The infarct size correlated with ischemic myocardial blood flow in both groups, but the slopes of regression lines relating the two variables did not differ between the two groups.

CONCLUSIONS

Short-term, diet-induced hypercholesterolemia increased infarct size in awake dogs. This change results, at least in part, from a decrease in collateral blood flow to ischemic myocardium during coronary artery occlusion.

Autogenous meniscus grafts in articular cartilage defects--an experimental study

Many methods have been attempted to repair defects in the articular cartilage involving the subchondral bone, but no satisfactory method has yet been established. We performed an experimental study utilizing autogenous meniscus grafts for defects in the articular cartilage involving the subchondral bone. Sixty-two knees of 31 rabbits were thus treated. Gross and histological examinations were performed in animals sequentially sacrificed after 2 to 24 weeks. In gross examinations, the articular surface was smooth and the degenerative changes were slight although the grafted area appeared as a piece of whitish meniscus in all experimental knees. Histologically, 12 weeks were necessary for complete union in the superficial zone of the junction between the grafted meniscus and the subchondral bone. However, the junction in the deep zone was completely united after two weeks. Degenerative changes, such as fibrillation or ulceration were not noted on the surface of the grafted meniscus. The chondrocytes of the meniscus survived for as long as 24 weeks. The autogenous meniscus graft appears to be a promising alternative for defects in the articular cartilage.

Cartilage lesions in the knee of adolescents and young adults: arthroscopic analysis

In this article, the mechanism of occurrence and development of cartilage lesions as well as the relationship between pain and conditions of cartilage lesions will be discussed. The study was based on the findings from arthroscopic analyses, plain radiographs, and arthrograms. Sixty-five joints of 63 patients with cartilage lesions were examined. We have made the following conclusions. Cartilage lesions do not start necessarily from the surface layers of the cartilage. Lesions may originate in the subchondral bone and develop toward the surface, causing severe pain. Cartilage lesions, resulting in little pain, are related closely to joint instability, indicating that the lesion occurrence is affected by unnatural shearing stress rather than by direct force applied to the joint surface. Thus, prevention and treatment should focus on removing the shearing stress. The purpose of this article is to examine how cartilage lesions relate to patient symptoms. Additionally, untreated lesions possibly could develop into the early stage of osteoarthrosis of the knee, causing exposure of the subchondral bone and thus continuous pain.

Acceleration of the hemopoietic reconstitution in mice undergoing bone marrow transplantation by recombinant human granulocyte colony-stimulating factor

We have investigated the effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on hemopoietic reconstitution after bone marrow transplantation (BMT) following lethal irradiation in mice. Mice received a daily administration of 10 micrograms/kg rG-CSF or control vehicle one through 21 days after BMT. Spleen colony-forming units (CFU-S), granulocyte-macrophage colony-forming units (CFU-GM), megakaryocyte colony-forming units (CFU-Meg), and erythroid burst-forming units (BFU-E) increased in both bone marrow and spleen of the rG-CSF-treated mice as compared with the control. This increase was evident during the administration period. In spite of the increase in the progenitor cells in bone marrow and spleen, only a recovery of neutrophils was accelerated in peripheral blood. Thus rG-CSF accelerated granulopoietic recovery in the BMT mice, with an enhanced recovery of the stem cells and the progenitors for erythrocytes and megakaryocytes. These results indicate the potential clinical usefulness of rG-CSF in the treatment of patients undergoing BMT.

[Pathogenesis of ipsilateral hemiparesis in patients with lateral medullary syndrome]

Lateral medullary syndrome is known to cause hemiparesis ipsilateral to the medullary lesion. However, it's clinical significance has not been fully evaluated. In this study, we made clinical and angiographic studies in patients with syndrome to elucidate the pathogenesis of ipsilateral hemiparesis. Thirty-four patients with cerebral infarction presenting with this syndrome were studied. Their mean age was 51 years and all the patients were examined within 6 months of their first attack. Diagnosis of ipsilateral hemiparesis was made if subjective feeling of weakness in the upper and lower extremities was associated with increased deep tendon reflexes. Ipsilateral hemiparesis was observed in 38% of all the patients. Cerebral angiography was performed in 26 patients and divided into two groups; group A with ipsilateral hemiparesis (n = 9) and group B without ipsilateral hemiparesis (n = 7). In 56% of patients in group A, angiography showed non-visualization of ipsilateral vertebral artery (VA) and posterior inferior cerebellar artery (PICA). Non-visualization of these two arteries never occurred in the patients of group B. On the other hand, non-visualization of VA alone was observed in 35% of the patients in group B, but it was none in the patients of group A. However, there were no differences in concerning the frequency of non-visualization of PICA alone or non-occlusion at all between both groups. Therefore, the focal ischemia in the region below the pyramidal decussation due to the occlusion of both VA and PICA, regardless of thrombotic or embolic episode, was considered to be responsible for ipsilateral hemiparesis.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of intrathoracic perineurial cyst]

A 67-year-old man was referred to our surgical clinic for evaluation of an abnormal shadow on the chest X-ray examination. CT scan and MRI revealed a tumor in the posterior mediastinum and destruction of the pedicle and intraspinal invagination by the tumor. The tumor in a paravertebral area are linked with a vertebral canal through a destructed intervertebral foramen. MRI showed that the tumor was a cyst which contained fluid. On thoracotomy a hen's egg sized cyst was found in the posterior mediastinum, the cyst was excised. Pathological diagnosis was a perineurial cyst. This case was clearly differentiated from an intrathoracic meningocele and a neurilemmoma microscopically. This case is the first intrathoracic perineurial cyst in Japan.

[A case of chondroblastoma originating from the right 6th rib]

Chondroblastomas are rare neoplasms, and comprise 0.5-1% of histologically proved primary bone tumors. We report a case of the tumor originating form the right 6th rib. The patient, a 15-year-old female, was admitted because the abnormal shadow was found on routine chest X-ray film. It was suspected to be the posterior mediastinal tumor based on the chest X-ray, CT and MRI. In surgery, the tumor was 4.0 x 4.0 x 2.5 cm in size and fixed on the rib, but not invasive to other tissue. The content was rough and soft granuloma like. Histological examination confirmed the diagnosis of chondroblastoma of the rib. The patient is doing well without symptoms of recurrence fifteen months after surgery.

Simple in vivo bioassay for erythropoietin

A new method of in vivo bioassay for erythropoietin (EPO) is described. This method is based on the measurement of immature reticulocytes in EPO-treated mice using an automatic microcell counter, and is simpler and more precise than the existing methods of polycythaemic mouse assay and starved rat assay. Normal mice were injected subcutaneously for 3 successive days with EPO at the doses between 0 and 9.6 IU/mouse. On the following day, 20 microliters of peripheral blood from each EPO-treated mouse was collected and haemolysed with a stromatolysing agent. Quicklyser. Residual particles derived from immature reticulocytes in the stromatolysed blood cells were counted using a microcell counter (Sysmex CC-180A) and a cell monitor (Sysmex CM-5). The number of the residual particles increased in a dose-dependent manner in EPO-treated mice. The mean of correlation coefficients of five log dose-response lines was 0.924, and the mean of precision indices was 0.138. A good correlation was also observed between the residual particle counts and reticulocyte counts obtained from smears.

Primitive erythropoiesis of mouse teratocarcinoma stem cells PCC3/A/1 in serum-free medium

Mouse teratocarcinoma stem cells PCC3/A/1 differentiated into various types of cells, such as red cells, when they were grown in serum-free medium containing transferrin and bovine serum albumin on a KCF cell feeder layer. These red cells were stained well with 2,7-diaminofluorene (DAF), and therefore were erythroid cells. They were nucleated and contained embryonic globin chains, immunologically identified with antiembryonic hemoglobin antisera after acid urea Triton X-100 polyacrylamide gel electrophoresis (UT-PAGE). The addition of erythropoietin to the culture medium enhanced the production of both embryonic and adult globin chains. The addition of interleukin-3 also enhanced the production of embryonic globin chains, but not the production of adult globin chains. These results indicated that primitive erythropoiesis of PCC3/A/1 teratocarcinoma cells did not require exogenous addition of any hematopoietic factor such as erythropoietin or interleukin-3. This culture system will be a new model system for investigating the factors regulating the primitive erythropoiesis in yolk sac blood islands.

Immature teratoma of the ovary

The purpose of this study was to establish the optimal management of immature teratoma of the ovary. Pursuant to this, 20 previously untreated patients with immature teratoma were evaluated. Nine patients were at stage I of the disease, 2 had progressed to stage II, and 9 to stage III. Eight patients had grade 1 tumors, 11 had grade 2 tumors, and 1 had a grade 3 tumor. Postoperative chemotherapy was performed in 19 cases. Vincristine, actinomycin D, and cyclophosphamide (VAC) were administered in 9 cases, chemotherapy including cisplatin (P) was administered in 8 cases, and other regimens were followed in the 2 remaining cases. The median follow-up period was 62 months (range 19-108 months), and no patient was lost to follow-up. After completion of the follow-up period, 18 patients were alive and disease free, 1 was alive with liver metastasis, and 1 had died. The patient who died had suffered from a grade 3 tumor, and the recurrent tumor was a rhabdomyosarcoma. As a result of this study, it was found that immature teratoma of grades 1 and 2 can be managed successfully with VAC or P therapy. Thus, a hysterectomy should not be automatically performed in patients who still hope to give birth, yet suffer from a grade 1 or 2 immature teratoma at the time of a second operation.

Reduced response to granulocyte colony-stimulating factor in W/Wv and Sl/Sld mice

The response of W/Wv and Sl/Sld mice to recombinant granulocyte colony-stimulating factor (rG-CSF) was investigated. Purified rG-CSF was injected every day for 1 week in doses up to 1000 micrograms/kg. Both untreated Sl/Sld and W/Wv mice initially showed an ordinary number of neutrophils and then an increase in neutrophils in response to rG-CSF injections. However, the effective dose of rG-CSF was much higher than that for normal mice. An increase in splenic CFU-GM was observed in both types of mice receiving 1000 micrograms/kg of rG-CSF, regardless of the reported defects in their hemopoietic system. These results indicate that W/Wv and Sl/Sld mice show a reduced response to exogenous rG-CSF and that a large amount of exogenous rG-CSF may allow an increase in neutrophils in certain hemopoietic defects.

Effects of recombinant human granulocyte colony-stimulating factor on the mice receiving bone marrow transplantation following lethal irradiation: acceleration of recovery of the peripheral blood neutrophils and potentiation of anti-Pseudomonas resistance

The effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on the recovery of peripheral blood neutrophil counts and resistance to i.p. infection by Pseudomonas aeruginosa were studied using a mouse bone marrow transplantation (BMT) model. A severe neutropenic period continued in the BMT mice for greater than 9 days following BMT. In contrast, the number of peripheral blood neutrophils in the BMT mice that received a daily administration of 2.5 micrograms of rG-CSF following BMT returned to normal by day 9. Thus, rG-CSF accelerated the recovery of the peripheral blood neutrophil counts in BMT mice. Anti-Pseudomonas resistance of the control BMT mice examined on days 7, 9, and 11 following BMT was one fifteenth to one fiftieth of normal mice, as indicated by the LD50 value. The anti-Pseudomonas resistance was elevated six- to sevenfold by the rG-CSF treatment. A marked increase in the neutrophils exudating into the peritoneal cavity in response to casein injection was observed in the rG-CSF-treated BMT mice. In addition, the reduced superoxide generative and phagocytic activity of the peritoneal neutrophils of the BMT mice were restored to normal by the rG-CSF treatment. It is suggested that rG-CSF potentiated anti-Pseudomonas resistance of the BMT mice by increasing neutrophils migrating to the infection site and restoring their functions; this may result from a prompt recovery of the peripheral blood neutrophil level together with the effect on neutrophil functions. These results indicate the clinical usefulness of rG-CSF in applications for BMT.

Physicochemical and biological characterization of asialoerythropoietin. Suppressive effects of sialic acid in the expression of biological activity of human erythropoietin in vitro

Various partially or fully desialylated human erythropoietins were obtained by neuraminidase digestion of the hormone, without non-specific proteolysis and degradation of carbohydrates. Asialoerythropoietin showed a specific activity of 220-IU/mg protein in vivo, although that of the intact erythropoietin was 2.2 x 10(5) IU/mg. A linear relationship was found between the logarithm of the specific activity in vivo and the number of sialic acids. The asialoerythropoietin showed a four-times-higher specific activity in vitro compared with intact erythropoietin using mouse bone marrow cells. It also showed an approximately six-times-higher specific activity in a colony-forming assay for the erythroid colony-forming unit and the erythroid burst-forming unit. Partially or fully de-N-glycosylated erythropoietin derivatives also showed lower in vivo activity but higher in vitro activity than the intact erythropoietin, dependent on the number of sialic acids. To clarify the reason for the enhanced biological activity of asialoerythropoietin in vitro, the binding of intact 125I-erythropoietin or 125I-asialoerythropoietin to cells containing specific receptors for the hormone was analyzed. 125I-asialoerythropoietin bound to spleen cells from anemic mice approximately five times faster than did intact 125I-erythropoietin. The amount of 125I-asialoerythropoietin internalized by target cells, measured in the absence of NaN3, was four times higher than that of intact erythropoietin. These results demonstrate that asialoerythropoietin binds to its receptor faster than the intact form. This may be the main reason for the increased activity of asialoerythropoietin in vitro.