The importance of preserving disc structure in surgical approaches to lumbar disc herniation

STUDY DESIGN

This study examined the clinical and radiographic results in patients with lumbar disc herniation treated surgically with one of four procedures: two different methods of herniotomy using a posterior approach and two different methods of percutaneous nucleotomy.

OBJECTIVES

The authors goal was to identify the structural changes in the disc after each of the procedures and to correlate them with the clinical outcome.

SUMMARY OF BACKGROUND DATA

The details of herniotomy procedure via a posterior approach or by percutaneous nucleotomy as described by many authors have not been consistent. Furthermore, previous reviews of these studies have been less than satisfactory.

METHODS

One hundred fifty-seven herniotomies using a posterior approach and 94 percutaneous nucleotomies were studied with a follow-up of at least 2 years. Each of these groups was divided into two subgroups to evaluate the role of the remaining nucleus pulposus in the central area of the disc.

RESULTS

Changes seen in imaging studies, such as a decrease in disc height and an increase of intervertebral instability in plain radiographs and a decrease in signal intensity of the disc in magnetic resonance images, were significantly less common in the subgroups of herniotomy and percutaneous nucleotomy in which the nucleus pulposus in the central area of the disc was preserved when compared with the subgroups in which a complete removal of the disc was attempted. The changes seen in the imaging studies were significant in patients younger than 40 years of age and correlated closely with the clinical results.

CONCLUSIONS

Preserving the nucleus pulposus during the surgical treatment of lumbar disc herniation in patients younger than 40 years of age resulted in better radiographic and clinical results.

Growth and metastasis of two canine mast cell tumors in SCID mice

Intermediately differentiated mast cell tumors in two dogs were subcutaneously xenotransplanted into severe combined immunodeficiency (SCID) mice. Both tumors primarily grew and were serially transplantable in SCID mice. The histological features of the xenografts were similar to those of original tumors in dogs. Both of these subcutaneous tumors were judged as connective tissue mast cells by toluidine blue stain. One of the two xenografts metastasized to the tracheobronchial lymph nodes, omentum, mesentery, subpleural region and retroperitoneum of the SCID mouse. These canine mast cell tumor xenografts in SCID mice may be valuable tools for investigating the growth and metastatic behaviors of the tumor.

Human monoclonal rheumatoid factors augment arthritis in mice by the activation of T cells

In order to investigate the in vivo role of rheumatoid factor (RF), the effects of the administration of human monoclonal (m) IgM-RF and IgG-RF on the development of arthritis in mice were examined. The administration of human mRFs into mice immunized with type II collagen (CII) markedly enhanced the clinical score and paw swelling. The severity of arthritic joint disease with a marked infiltration of lymphoid cells, proliferation of synovial membrane, pannus formation and destruction of articular cartilage was significantly enhanced in both groups receiving RF (RF-enhanced arthritis). Skin ulcers were also observed in some of these RF-enhanced arthritis mice, whereas no such signs were observed in CII-immunized mice without mRFs. Both IgM-RF and IgG-RF increased CII-specific IgG antibodies in circulation, and the severity of arthritis correlated with the production of high titres of anti-CII antibodies. In vivo treatment of RF-enhanced arthritis mice with an anti-CD4 MoAb or an anti-CD8 MoAb inhibited the induction and progression of arthritis in these mice. Administration of RF to severe combined immunodeficient (SCID) mice with arthritis developed by the transfer of spleen cells from CII-immunized mice, prolonged the arthritis and enhanced the severity. This murine model of RF-enhanced arthritis may provide a useful tool for analysing the pathogenesis of rheumatoid arthritis in RF-positive patients.

A poliovirus-susceptible transgenic mouse model as a possible replacement for the monkey neurovirulence test of oral poliovirus vaccine

Two poliovirus-susceptible transgenic mouse (Tg PVR) strains, Tg1 and Tg21, were compared with the monkey test for their sensitivity to neurovirulence of live oral poliovirus vaccine (OPV). Intracerebral (i.c.) and intraspinal (i.s.) routes of inoculation were investigated to determine the most suitable combination of mouse strain and route. Evaluation of the mouse tests was performed using several indicators; clinical score and failure time were selected as the most efficient. Tg1 and Tg21 mice inoculated i.s. with type 2, and Tg21 mice inoculated i.s. with type 3 OPV were determined to be the most appropriate systems, whereas they are shown not to be suitable for type 1 OPV. The sensitivity of each of the two mouse models was at least equal to that of the monkey test, suggesting that these mouse systems might be considered as a potential replacement for the monkey test of OPV. However, more data are needed to establish regulatory criteria of acceptability for vaccine lots tested in Tg PVR mice. This is the first study conducted with Tg PVR mice with all three types of poliovirus vaccine preparations.

Genetic basis of the neurovirulence of type 1 polioviruses isolated from vaccine-associated paralytic patients

We examined four type 1 polioviruses isolated from the stools of patients with vaccine-associated paralytic poliomyelitis in China. All of these isolates were shown to be Sabin derived viruses by restriction fragment length polymorphism assay after polymerase chain reaction and by sequencing of the viral genome encoding the viral coat protein, VP1. However, the same analysis of the 3D coding region suggested that two of the four isolates had the sequence of wild type poliovirus in the tested region. Furthermore there were also point mutations in the 5' non-coding region. One was a single base change from U to C at nucleotide position 525, and the other three were from G to A at position 480. All the four strains were more neurovirulent that Sabin type 1 virus in transgenic mice with human poliovirus receptor gene. The data showed that the nucleotide positions of type 1 poliovirus which were identified to be in favor of the high neurovirulence were indeed changed during natural transmission, and suggested that the point mutation alone or a recombination of the vaccine type with wild type genome results in an acquisition of neurovirulence.

Increased delivery of a new cisplatin analogue (254-S) in a rat brain tumor by an intracarotid infusion of bradykinin

The intracarotid infusion of bradykinin has been shown to selectively increase capillary permeability in a brain tumor without affecting either normal brain capillary permeability or the systemic blood pressure. We examined whether the intracarotid infusion of bradykinin could selectively increase the delivery of a new watersoluble antitumor agent, cis-diammine glycolato-platinum (254-S, 303.2 mol. wt.), to transplanted RG2 glioma in rats. The platinum contents in the brain, tumor tissues and plasma were measured using an atomic absorption spectrophotometer. The transfer ratio of 254-S from plasma to the tissues was calculated and expressed as the volume of plasma containing platinum per g tissue (Dp, microliter g-1). Intracarotid bradykinin infusion at a rate of 20 micrograms kg-1 min-1 increased the delivery of 254-S in the tumor tissue by 1.3-fold when compared with intracarotid infusion of 0.9% saline (48.78 +/- 18.11 vs. 37.12 +/- 12.53; p < 0.05). In normal brain tissue including the ipsilateral cortex, the contralateral basal ganglia and the contralateral cortex, bradykinin did not significantly increase the delivery of 254-S in comparison with 0.9% saline (12.28 +/- 9.53 vs. 10.70 +/- 5.05, 4.96 +/- 3.54 vs 4.96 +/- 4.80, 7.64 +/- 4.10 vs. 13.07 +/- 11.38, respectively). These results indicate that the intracarotid infusion of bradykinin selectively increases the delivery of 254-S to the brain tumor without affecting the normal brain. This method may, therefore, enhance the antitumor effect of 254-S for the treatment of brain tumors and also reduce neurotoxicity in the normal brain.

Antigen receptor-mediated B cell death is blocked by signaling via CD72 or treatment with dextran sulfate and is defective in autoimmunity-prone mice

Mature B cells undergo programmed cell death when surface (s) Ig is extensively multimerized. A signal that blocks death of B cells is thus required for activation of B cells in response to antigen stimulation. Here we show that only a few diverse transmembrane signals capable of inducing activation and proliferation of B cells blocked sig-mediated death of normal mature B cells, and that there is no correlation between mitogenic activity and the ability to rescue B cells from death. The results suggest that a specific signal is required for abrogating B cell death induced by sig cross-linking. Signaling via IL-4 receptor and CD40, both of which are derived from activated T cells, blocked sig-mediated death, as described previously. Signaling through a B cell antigen CD72, a counter-receptor of the pan-T antigen CD5, also blocked death of anti-Ig-treated mouse spleen B cells. CD72 signal may play a role in survival of B cells at the initial step of T-B interaction, where resting T cells recognize antigens presented by B cells. Moreover, B cell death by anti-Ig was blocked by T cell-independent antigens such as lipopolysaccharide and dextran sulfate, and spleen B cells from New Zealand mice, which are prone to autoantibody-dependent autoimmune diseases, were resistant to sig-mediated death. Mechanisms for blocking sig-mediated death may therefore be required in antibody response to foreign antigens regardless of T independence or T dependence and in autoantibody production.

Effects of feeding on conditioned avoidance responses in rats

Possible effects of feeding on learning were studied by comparing learned avoidance rates among three groups of Wistar rats that were given a diet at 1 h (1-h pretest group) and 5 h (5-h pretest group) before and immediately after (post-test group) the conditioned avoidance test. Learned avoidance rates during eight test sessions were higher in the order of the 1-h pretest, post-test, and 5-h pretest groups. This suggests that both pre- and post-test (training) feeding facilitates acquisition of conditioned avoidance learning presumably based on neurohumoral processes influenced by available glucose concentrations.

Effects of cerebroventricle administration of acidic fibroblast growth factor on conditioned taste aversion learning in rats

Wistar strain rats were given acidic fibroblast growth factor (aFGF) or denatured aFGF into their cerebroventricle before taste aversion conditioning for saccharin solution. Animals administered with aFGF showed significantly lower aversion threshold for saccharin at the 1st day and preference ratios for saccharin vs distilled water at the 4th, 6th, and 7th day after the conditioning than those administered with denatured aFGF. These results suggests that aFGF in the cerebrospinal fluid facilitates acquisition of the conditioned taste aversion learning.

Development of radioimmunoassay for human leptin

Using recombinant human leptin, we have produced an antiserum for human leptin and developed a radioimmunoassay (RIA) specific and sensitive for human leptin. We detected leptin-like immunoreactivity (-LI) in culture media of adipose tissue from subcutaneous abdominal fat in human. The plasma leptin-LI concentration in nonobese subjects (17.6 <body mass index (BMI)<23.0) was 5.6 +/- 1.3 (mean +/-SE) ng/ml, while that in obese subjects (29.0 <BMI) was 43.0 +/- 9.4 (mean +/- SE) ng/ml. In gel permeation chromatographic analyses, leptin-LI in culture media and plasma consisted of single component emerging at the elution position of recombinant human leptin. These findings indicate that leptin is secreted from the adipose tissue into the circulating blood as a large molecular form corresponding to recombinant leptin. The RIA developed in the present study will be a powerful tool to investigate the physiological and pathophysiological significance of leptin in human.

Similarity among the Drosophila (6-4)photolyase, a human photolyase homolog, and the DNA photolyase-blue-light photoreceptor family

Ultraviolet light (UV)-induced DNA damage can be repaired by DNA photolyase in a light-dependent manner. Two types of photolyase are known, one specific for cyclobutane pyrimidine dimers (CPD photolyase) and another specific for pyrimidine (6-4) pyrimidone photoproducts[(6-4)photolyase]. In contrast to the CPD photolyase, which has been detected in a wide variety of organisms, the (6-4)photolyase has been found only in Drosophila melanogaster. In the present study a gene encoding the Drosophila(6-4)photolyase ws cloned, and the deduced amino acid sequence of the product was found to be similar to the CPD photolyase and to the blue-light photoreceptor of plants. A homolog of the Drosophila (6-4)photolyase gene was also cloned from human cells.

Plasma soluble interleukin-2 receptor level in patients with primary myelodysplastic syndromes: a relationship with disease subtype and clinical outcome

To assess the hypothesis that the plasma soluble interleukin-2 receptor (sIL-2R) level may have predictive value for morbidity/mortality in patients with myelodysplastic syndromes (MDS), we determined in plasma sIL-2R level of 80 MDS patients and examined their subsequent clinical course. Compared with low-risk MDS (refractory anaemia (RA) and RA with ringed sideroblasts) patients and normal subjects, the plasma sIL-2R level was significantly elevated in high-risk MDS (three other MDS subtypes and acute leukaemia following MDS) patients (high-risk MDS versus low-risk MDS, P < 0.01; high-risk MDS versus normal subjects, P < 0.01). 14/40 low-risk MDS patients developed at least one of the following during the follow-up period: erythrocyte transfusion dependence, infections requiring hospitalization, disease progression or MDS-related death. The plasma sIL-2R level was higher in these eventful subjects than in event-free low-risk subjects (P < 0.0001), and all of 10 low-risk subjects with a plasma sIL-2R level > 540 U/ml experience at least one event. By logistic regression analysis of various parameters in these 40 low-risk subjects, the plasma sIL-2R level was identified as the strongest independent parameter for predicting eventful subjects (P < 0.0047). The plasma sIL-2R level did not show a predictive value in high-risk MDS. This study revealed that the plasma sIL-2R level is significantly elevated in high-risk MDS and suggested that the plasma sIL-2R level is a valuable predictive factors for the clinical outcome in low-risk MDS.

[Efficacy of cefditoren pivoxil in the treatment of acute otitis media due to benzylpenicillin-insensitive Streptococcus pneumoniae]

Clinical and bacteriological studies were carried out on cefditoren pivoxil (CDTR-PI) granule in infantile purulent acute otitis media treated at general practice settings and the following findings were obtained: 1. Two hundred forty eight strains were isolated from 210 patients, almost all of which (81.1%) harbored the following two strains: Streptococcus pneumoniae (42.3%) and Haemophilus influenzae (38.8%). Among S. pneumoniae, benzylpenicillin (PCG)-insensitive S. pneumoniae, (PISP) or PCG-resistant S. pneumoniae (PRSP) was 36.2%, corresponding to 15.3% of all the isolates and found in 18% of all patients. 2. The bacteria in the middle ear discharge and the nasopharyngeal swabs were correlated with conformity rate of more than 80% with regard to Streptococcus pyogenes, S. pneumoniae and H. influenzae but no Staphylococcus aureus was detected simultaneously from the two sources in any of the patients. S. aureus and coagulase-negative staphylococci (CNS) were considered to be contaminants that were originated from the external auditory meatus at the time of sampling. 3. Frequencies of isolation of S. pneumoniae from different age groups were higher in a lower age group between 0 and 4 years and those of PISP or PRSP had the similar tendency. 4. Antibacterial activities were determined for CDTR and related oral antibiotics against the strains of S. pneumoniae and H. influenzae as representative isolates. CDTR had stronger antibacterial activities against both bacteria than the reference antibiotics. CDTR was found to be transferred into the otorrhea at a mean concentration of 0.58 micrograms/ml after single administration of CDTR-PI granule formulation at 3 mg(potency)/kg. 5. As for bacterial eradication efficacies in the middle ear cavity and the nasopharynx, eradication rates were higher than 80% in the middle ear cavity in all cases without large differences among bacterial species but eradication rate of PISP was 30% in the nasopharynx, and it was significantly lower than those of PSSP and other bacteria. 6. In view of clinical effectiveness, the efficacy rate was 89.4% and bacteriological effects was 92.2%; in view of safety, adverse reactions were; observed in 9.5% and the rate of usefulness was 89.4%. 7. From above-stated results, CDTR-PI was considered as a useful oral antibiotic for infantile acute otitis media including PISP infections.

High-dose intravenous gamma globulin reduces macrophage colony-stimulating factor levels in idiopathic thrombocytopenic purpura

We investigated the effect of high-dose intravenous gamma globulin therapy on the plasma level of macrophage-colony stimulating factor (M-CSF) level in 13 patients with chronic idiopathic thrombocytopenic purpura. M-CSF and interleukin-6 levels were determined by enzyme-linked immunosorbent assay. The mean +/- S.D. level of M-CSF in the patients was 1235 +/- 439 U/ml, and the level in 8 patients was higher than the mean + S.D. (903.6 U/ml) in normal controls. All 8 patients had steroid-refractory disease. M-CSF levels were significantly correlated with the serum levels of interleukin-6 (r = 0.66, P < 0.05). Interleukin-6 levels were also significantly raised in the high M-CSF group compared with the normal M-CSF group (P < 0.05). In the whole patient population, M-CSF levels decreased, but not significantly, after intravenous gamma globulin, while interleukin-6 decreased significantly. However, in the patients with high pretreatment M-CSF levels, both M-CSF and interleukin-6 decreased significantly after treatment (M-CSF, 4 weeks, P < 0.05; IL-6, 1 week, P < 0.05, 4 weeks, P < 0.01). These findings suggest that high-dose intravenous gamma globulin causes thrombocytosis by the decrease of M-CSF levels in idiopathic thrombocytopenic purpura.

In vitro pharmacological profile of YM-43611, a novel D2-like receptor antagonist with high affinity and selectivity for dopamine D3 and D4 receptors

1. We investigated some neurochemical properties of a novel benzamide, YM-43611, [(S)-N-(1-benzyl-3-pyrrolidinyl)-5-chloro-4-cyclopropylcarbonylamino+ ++-2- methoxybenzamide] in comparison with putative D2-like receptor antagonists using both rat and human cloned dopamine D2-like receptors in vitro. 2. Receptor binding studies revealed that YM-43611 had appropriately potent affinities for both rat and human D2-like receptors, with moderate selectivity for D3 receptors and high selectivity for D4 receptors over D2 receptors (Ki values (nM) for rat receptors: D2, 165; D3, 35.5; D4, 1.85, and for human receptors: D2, 42.9; D3, 11.2; D4, 2.10). 3. YM-43611 displayed weak or negligible affinity for other neurotransmitter receptors, namely D1, D5, alpha(1), alpha(2), beta, 5-HT1A, 5-HT2A, 5-HT3, H1, M1 and M2 receptors. 4. Dopamine stimulated low-Km GTPase activity on membranes from Chinese hamster ovary (CHO) cells expressing the human D2-like receptor subtype. This response to dopamine of low-Km GTPase activity was inhibited by use of putative D2-like receptor antagonists. YM-43611 showed a moderate selectivity for D3 receptors (Ki = 45.5 nM) and a high selectivity for D4 receptors (Ki = 3.28 nM) over D2 receptors (Ki = 70.6 nM). 5. Dopamine inhibited forskolin-stimulated adenylate cyclase in intact CHO cells expressing the human D2-like receptor subtype. YM-43611 shifted the inhibition curve of dopamine on respective D2-like receptor subtype-mediated cyclic AMP formation to the right in a parallel fashion, showing a pA2 value of 7.42 (38.1 nM) for D2 receptors, a pKB value of 8.06 (8.68 nM) for D3 receptors, and a pA2 value of 8.42 (3.77 nM) for D4 receptors. 6. YM-43611 but not the other D2-like receptor antagonists exhibited good selectivity with respect to dual antagonism for D3 and D4 receptors in both receptor binding and functional assays. 7. These results indicate that YM-43611 is a novel D2-like receptor antagonist with high potency and selectivity for both D3 and D4 receptors. YM-43611 is therefore expected to be valuable in exploration of the physiological role of D3 and D4 receptors.

Establishment and characterization of transgenic mice expressing human platelet glycoprotein Ib alpha

The platelet glycoprotein (GP) Ib/IX/V is a hetero-oligomeric receptor complex for von Willebrand factor (vWF) and mediates platelet adhesion and aggregation under high shear stress conditions. It is composed of alpha and beta chain of GP Ib, GP IX, AND and GP V. To establish transgenic mice carrying human GP Ib alpha, we injected into mouse zygotes a 6 kb DNA fragment containing human GP Ib alpha gene that included entire coding sequence and putative promoter region. One hundred and thirteen offsprings were screened, and only one was found to express human GP Ib alpha protein and has passed the human GP Ib alpha gene as well as the expression of the gene to next generation. The expression of human GP Ib alpha in transgenic mice was limited to platelets and megakaryocytes. Glycocalicin, a proteolytic fragment of human GP Ib alpha found in normal human plasma, was not detected in transgenic mouse plasma. Human vWF in the presence of ristocetin supported agglutination of transgenic mouse platelets, but not of control mouse platelets.

[Five cases of hereditary high red cell membrane phosphatidylcholine hemolytic anemia in three families]

Five cases of hereditary high red cell membrane phosphatidylcholine hemolytic anemia in three families were described. All cases were clinically manifested by jaundice and splenomegaly. Hemolysis was evident from indirect hyperbilrubinemia, reticulocytosis and decrement of serum haptoglobin. Red blood cells showed morphological abnormalities such as poikylocytosis, anisocytosis and target cells on blood smears. Both direct and indirect Coombs' tests were negative. Ham test, sugar water test and hemoglobin electrophoresis showed no abnormalities. Osmotic fragility test showed decreased membrane fragility. Lipid analysis of red cell membrane showed increment of phosphatidylcholine content and decrement of sphingomyelin content, although plasma lipids were essentially normal. Influx and efflux of sodium through the red cell membrane were both increased. Splenectomy was performed without effect on one patient and the mother of other patients.

Expression of mRNA for matrix metalloproteinases and tissue inhibitors of metalloproteinases in periodontitis-affected human gingival tissue

It is known that the host responds to an increased concentration of collagenase [or matrix metalloproteinase (MMP)-1] by preferentially expressing mRNA for the tissue inhibitor of metalloproteinase-1 (TIMP-1) in order to overcome tissue destruction due to periodontitis. To further elucidate the relation between MMPs and TIMPs in periodontitis-affected tissues, the expression of mRNA for MMP-1, -3 and -8, and TIMP-1 and -2, in 10 gingival samples from patients and five from healthy individuals was assessed by reverse transcription-polymerase chain reaction. The diseased group showed significantly higher levels of MMP-1, -3, -8 and TIMP-1 mRNA relative to beta-actin than the control group (mean +/- SE: diseased vs healthy (%): 0.26 +/- 0.05 vs 0.018 +/- 0.0040 for MMP-1; 0.09 +/- 0.16 vs 0.063 +/- 0.016 for MMP-3; 0.068 +/- 0.017 vs 0.006 +/- 0.0010 for MMP-8; 12.66 +/- 2.90 vs 2.71 +/- 0.54 for TIMP-1; p < 0.01). TIMP-2 did not significantly differ between the two groups (1.79 +/- 0.33 vs 1.42 +/- 0.53; p > 0.05). The preferential increase in the level of MMP-3 mRNA relative to that of MMP-1 and -8 in inflamed gingiva would be relevant to tissue destruction because MMP-3 is a broad-spectrum MMP and a pivotal activator of latent MMP-1 and -8. Therefore, the overall increase in MMP-1, -3 and -8 mRNA in periodontitis-affected gingiva might account for a concerted action of MMPs during connective tissue destruction in periodontitis.

Purification and characterization of active fragment of Ca2+/calmodulin-dependent protein kinase II from the post-synaptic density in the rat forebrain

Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) of the post-synaptic density (PSD) was solubilized and activated 4- to 5-fold by limited alpha-chymotrypsin digestion with prior autophosphorylation of the kinase. The enzyme was also activated by trypsin and mu-calpain, a Ca(2+)-dependent protease. The active catalytic fragment was purified to homogeneity using gel filtration and ion exchange chromatography. The purified active fragment was completely Ca2+/calmodulin-independent and exists as a monomer. Kinetic studies with the purified fragment revealed similar Km values for ATP and synthetic peptide substrate, and an about 8-fold increment in Vmax, compared with native PSD CaM kinase II.

DCC protein expression in hematopoietic cell populations and its relation to leukemogenesis

Using flow cytometry and immunoprecipitation (IP), we have investigated the deleted in colon cancer (DCC) protein expression on the bone marrow (BM) and peripheral blood (PB) cells of 16 normal subjects, 17 myelodysplastic syndrome (MDS) patients, and 10 acute myelogenous leukemia (AML) patients. With regard to the BM mononuclear cells (BM-MNCs) of normal subjects, the DCC protein expression ranged from 6.6 to 57.0%. Two-color flow cytometry revealed that among the IBM-MNCs the DCC protein was clearly expressed on the CD14+, CD13+, and factor 8+ cells, whereas it was low on the CD19+ and CD7+ cells and did not express on the CD34+, CD8+, and the glycophorin A+ cells. Further, the DCC protein expression was not seen on the PB CD11b+ and CD13+ cells. The IP results revealed that the 180-kD DCC protein was detected on the MNCs of both the BM and PB cells by the antibodies AF5, specific for the DCC extracellular domain, and G97-449, specific for the cytoplasmic domain. In contrast, flow cytometry did not detect the DCC protein on any BM-MNC MDS lineages (0.1-1.5%) or on AML leukemic cells (0.1-0.9%). The IP results indicated that the AF5 antibody did not detect the DCC protein on BM-MNCs of three of five MDS patients and four of five AML patients; however, the G97-449 antibody detected the 180-kD DCC protein in two MDS patients in whom AF5 had detected greatly reduced DCC band. These findings suggest that the DCC protein presence appears to be associated with normal hematopoiesis, and that its absence on the surfaces of the BM-MNCs and AML cells may contribute to the MDS and AML pathogenesis.

Biliary excretion of polystyrene microspheres with covalently linked FITC fluorescence after oral and parenteral administration to male Wistar rats

To further our understanding of microspheres as a drug delivery system, the biliary excretion of covalently linked FITC fluorescence polystyrene microspheres of various diameters was investigated after oral and parenteral administration to male Wistar rats. About 36%, 16% 3% and 1% of the dose was excreted into the bile after parenteral injection of 50 nm, 500 nm, 1 micron and 3 microns diameter microspheres, respectively, over 24 h. In addition, about 30%, 11%, 1%, and 1% of the dose, respectively, was found in the blood at 24 h. After oral administration of 50 nm, 500 nm, and 1 micron microspheres, the recovery was about 18%, 8% and 1% of the dose in the bile and about 9%, 1%, and 0% in the blood, respectively. No 3 microns microspheres were detected in the bile or blood after oral administration. Particles were not detected in the urine of any group tested. Thus, the present study demonstrated that biliary excretion plays an important role in the disposition of microspheres administered by the oral or parenteral routes, and there is a size-related excretion of microspheres into the bile.