Effects of cycloheximide on chromatin-bound and -unbound PCNA in HeLa cells

We examined the effects of cycloheximide on the amount of chromatin-bound and -unbound PCNA subpopulations in HeLa cells. The chromatin-bound PCNA content decreased rapidly in the presence of cycloheximide, whereas the reduction of the total amount of PCNA was minimal even 24 h after the treatment with cycloheximide. From these data, the half-life of PCNA was estimated to be 31.0 h for chromatin-bound PCNA and 276.8 h for the total.

Benzylphthalimides and phenethylphthalimides with thalidomide-like activity on the production of tumor necrosis factor alpha

Benzylphthalimide analogs (P1P's) and phenethylphthalimide analogs (P2P's) have been found to exhibit thalidomide-like activity on the production of tumor necrosis factor (TNF)-alpha by the human leukemia cell line, HL-60, stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA). Structure-activity relationships are discussed on the basis of the TNF-alpha production-enhancing activity. Benzylphthalimide (P1P-00) exhibited which is weaker than that of thalidomide, but introduction of a methyl group at the ortho-position of the benzyl moiety (P1P-10) resulted an increase to a level comparable with that of thalidomide. Phenethylphthalimide (P2P-00) is more potent than thalidomide, and its fluorinated derivative, 2-phenethyl-4,5,6,7-tetrafluoro-1H-isoindole-1,3-dione (FP2P-00), exhibited potent activity at very low concentrations.

Nucleotide sequence surrounding the locus marker D21S246 on human chromosome 21

Most of the human Not I linking clones identified to date are considered to be derived from CpG islands because of the recognition sequence of this enzyme, and CpG islands have been reported to be located around the 5' regions of genes. As a pilot study, we determined the complete nucleotide sequence (41,924 bp) of a human cosmid clone (LL21NC02Q7A10) containing the marker D21S246 originating from a Not I linking clone. As a result of sequence analysis, we successfully mapped and revealed the genomic gene structure for KIAA0002 previously reported as a cDNA clone. This gene consists of 15 exons and was shown to exist at the D21S246 locus on human chromosome 21q21.3-q22.1. These results demonstrated that genomic marker-anchored DNA sequencing is a useful approach for the human genome project.

An epidermal growth factor receptor-leukocyte tyrosine kinase chimeric receptor generates ligand-dependent growth signals through the Ras signaling pathway

Leukocyte tyrosine kinase (LTK) is a receptor tyrosine kinase that belongs to the insulin receptor family. LTK is mainly expressed in pre B cells and brain. Previously we cloned the full-length cDNA of human LTK, but no ligands have so far been identified, and hence, very little is known about the physiological role of LTK. To analyze the function of the LTK kinase, we constructed chimeric receptors composed of the extracellular domain of epidermal growth factor receptor and the transmembrane and the cytoplasmic domains of LTK and established cell lines that stably express these chimeric molecules. When cultured in medium containing EGF, growth of these cell lines was stimulated, and these fusion proteins became autophosphorylated and associated with Shc in vivo in a ligand-dependent manner. By treatment with EGF, Shc was associated with the Grb2/Ash-Sos complex. Our analyses demonstrate that LTK associates with Grb2/Ash through an internal adaptor, Shc, depending on a ligand stimulation. The LTK binding site for Shc was tyrosine 862 at the carboxyl-terminal domain and to a lesser extent tyrosine 485 at the juxtamembrane domain. Both of them are located in NP/AXY motif which is consistent with binding sites for Shc. These findings demonstrate that LTK can activate the Ras pathway in a ligand-dependent manner and that at least one of the functions of this kinase is involved in the cell growth.

Theoretical analysis of the spatial phase-matching loci for second-harmonic generation and multiwave-mixing interactions

We report a theoretical analysis on spatial noncolinear phase matching of multiwave mixing and its application to a second-harmonic-generation (SHG) experiment. From the numeric calculations, the noncolinear phase-matching properties in general situations were determined. The theory gives the applicability for all noncolinear phase matching. Fine coincidences between theoretical calculations and observed spatial loci on noncollinear phase-matching SHG were confirmed. Relations that allow the calculation of the noncollinear phase-matching angle for any case of SHG are established. As an example, the noncolinear phase-matched SHG pattern on a screen is calculated numerically in the case of SHG of 1064 nm from a Nd:YAG laser under the phase-matched condition for two organic nonlinear crystals: 1-(2-thienyl)-3-(4-methyphenyl) propene-1 (TC-28), which is biaxial, and (2-furyl) methacrylic anhydride (FMA), which is uniaxial. Experimental results compared quite favorably with the theoretical analysis. Noncolinear phase matching may be of great practical interest in optical multiwave-mixing processes, such as optical parametric oscillation and optical parametric amplification. This technique also can be used for the measurement of crystal optical constants.

Cell-type-specific ras mutations but no microsatellite instability in chemically induced mouse skin tumors and transformed 3T3 cells

In mouse skin, both papillomas/carcinomas or fibrosarcomas can be induced by 7,12-dimethylbenz[alpha]anthracene (DMBA) depending on the mode of administration. Thus, upon DMBA painting (or transplacental exposure by i.p. injection to pregnant mothers) followed by 12-O-tetradecanoylphorbol-13-acetate applications to the skin of CD1 mice, papillomas and carcinomas appeared, whereas fibrosarcomas were induced when DMBA was s.c. injected. Molecular analysis of these tumors revealed that the majority of papillomas (17/20) and carcinomas (9/10) showed DMBA-specific mutations (A to T transversion at the 61st codon) in the Ha-ras gene. On the other hand, many fibrosarcomas (5/9) showed the same mutation only in the Ki-ras gene. When microsatellites were studied in these tumors at nine loci containing CA repeats, none of them showed an instability. In addition, when we analyzed 14 BALB/c 3T3 cell lines transformed by various carcinogens (including 3 clones induced by DMBA which have the A to T mutation in the Ki-ras gene), no changes in CA repeats were observed. These results suggest that DMBA-induced mouse tumors/transformed cells show cell-type-specific ras gene mutations, and these occur independently in the absence of microsatellite instability. While murine cells are considered to be relatively susceptible to cancer induction partially due to genomic instability, our results indicate that microsatellite instability is not induced in these cells by chemical carcinogens.

Bopindolol is a slowly dissociating beta 1-adrenoceptor antagonist when compared to other beta-blockers

This study used radioligand binding assay methods and pharmacological experiments to examine whether bopindolol, possessing a long-lasting action in addition to potent beta-adrenoceptor antagonistic effects, is a slowly dissociating antagonist. In addition, the slow dissociation of two of its metabolites, 18-502 (4-(3-tert-butylamino-2-hydroxypropoxy)-2-methyl indole) and 20-785 (4-(3-tert-butylaminopropoxy)-2-carboxyl indole), which have potent beta-blocking activities, was also assessed. The blockade of 3H-CGP12177 binding sites in rat heart and brain induced by pindolol was readily reversed by washing, whereas this inhibition by bopindolol and 18-502 was not easily reversed by washing. In addition, specific bindings of the hearts of the treatment animals with 20-785, atenolol, (+/-)propranolol, nadolol and celiprolol and of washout were 86.7, 78.8, 77.5, 82.3 and 79.9% of the control, respectively. These blockades by the treatment of each drug and washout in the brain were, however, lower than those in the hearts. On the other hand, when the left and right atria were pretreated with propranolol, bopindolol and 18-502, the inotropic and chronotropic actions of isoprenaline were inhibited by these drugs even though they were not present in the extracellular medium. Pretreatment with 20-785, atenolol and nadolol was readily reversed for both inotropic action and chronotropic rate, and inhibition by celiprolol and pindolol remained at 25% of the control at 240 min after treatment with these drugs. A good correlation between inhibitory binding percentage in the hearts and inhibitory inotropic or chronotropic actions were observed, although it was not observed in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

An electron microscopic study of the processes of nerve regeneration after lyophilized nerve homografting

The objective of the present study was to investigate the role of the Schwann cell basal lamina in nerve regeneration. To achieve this goal, we observed the process of axonal regeneration within a lyophilized nerve graft, in which only the basal lamina of the Schwann cell persisted. Sciatic nerves were removed from rats and lyophilized to kill the Schwann cells and other components. These grafts were transplanted to rat sciatic nerve defects. The rats were then killed after lapses of time. We observed the processes of axonal regeneration using a transmission electron microscope. Regeneration of axons along the inner surface of the Schwann cell basal lamina was clearly seen. These results suggest that, if tubular basal laminae persist, Schwann cells are not always necessary, and axonal regeneration can be induced in the direction toward the basal lamina.

[Respiratory disorders during sleep in Duchenne muscular dystrophy]

Respiratory disorders during sleep were studied in 42 patients with Duchenne muscular dystrophy (DMD) (mean age 18.4 years). Chest and abdominal movement, nasal airflow, snoring sounds, eye movement, and oxygen saturation were monitored during sleep. Three patterns of disorders were found: obstructive apnea, central apnea, and paradoxical respiration without upper airway obstruction (non-obstructive paradoxical respiration). Of these three patterns, obstructive apnea was the most common. Hypertrophy of the tongue and collapsibility of the upper airway seemed to be responsible for the obstructive apnea in these patients. The relationships between PaCO2 while breathing room air and the various indices of respiratory disorders were studied. The index of central apnea differed significantly between patients in whom PaCO2 was less than 50 Torr (early disease, n = 22) and those in whom PaCO2 was greater than or equal to 50 Torr (advanced disease, n = 20), but the indices of obstructive apnea and non-obstructive paradoxical respiration did not differ between those two groups. In conclusion, sleep disorders were common in patients with DMD, and the most common was obstructive apnea. In the patients with advanced DMD, blood gas analysis showed hypercapnia, and the index of central sleep apnea was high, probably because of respiratory muscle weakness or abnormalities in the respiratory center.

Potential parameters of male reproductive toxicity: reproductive performance, histopathology and sperm evaluation in SD rats given nitrazepam

The present study was designed to elucidate the correlation between findings from reproductive performance testing and those from histopathological examination of the testis and sperm analysis in rats given a benzodiazepine derivative, nitrazepam, for 2 and 4 weeks. The mechanisms of toxicological action of nitrazepam on the male reproductive organs were also investigated. Nitrazepam was given orally to Sprague-Dawley male rats (6-week-old) at a daily dose of 80 mg/kg for 2 weeks or at daily doses of 20, 40 or 80 mg/kg for 4 weeks. Treated males were mated to examine reproductive performance with untreated females after each dosing period, and after 4 and 9 week of recovery periods. Necropsy was performed for histopathological examination of the testis and epididymis and for sperm analysis after each dosing period and the final mating trial (total of 11 weeks recovery). In the findings from reproductive performance testing, significant decrease in the fertility index was observed in the 80 mg/kg group even after 2 weeks dosing and thereafter until 4 weeks recovery, though the mating index did not significantly differ from that of controls through the experiment. In the histopathological examination and sperm analysis, testicular signs of toxicity, decrease in number of sperm heads in the testis and increase in number of sperm with abnormal heads in the seminiferous tubules were noted in the 80 mg/kg group after 2 weeks dosing and in the 40 and 80 mg/kg groups after 4 weeks dosing. Concentrations of plasma testosterone and content of testis testosterone in nitrazepam-treated groups were not significantly different from those of controls. Plasma FSH concentration was significantly elevated in the 80 mg/kg group through the experiment, although significant elevation of plasma LH was observed only after 2 weeks dosing. These results indicate that histopathological examination is the most reliable approach to detect male reproductive adverse effects induced by nitrazepam rather than using parameters from mating trials. The four-week-dosing period is appropriate for their detection. Hypospermatogenesis induced by nitrazepam is suggested to be caused by direct action of nitrazepam on germ cells and/or Sertoli cells rather than by indirect action through inhibition of testosterone secretion.

Macrophage colony stimulating factor inhibits experimental liver metastases from colon cancer

This study investigated the inhibitory effect of human macrophage colony stimulating factor (hM-CSF) on experimental liver metastases. Murine colon cancer cell lines C-26 and C-36 were each injected into the spleen of BALB/c mice and the number of subsequent liver metastases was counted. An optimal dose (3,000U/body/day) of hM-CSF to inhibit liver metastases was identified. Additionally, hM-CSF (3,000U/body/day) administration for 7 days before and after the injection of the same cancer cell lines was investigated. The mean number of liver metastases decreased significantly in the hM-CSF group compared with the saline group. These results suggest potential therapeutic benefit for the use of hM-CSF in the adjuvant treatment of liver metastases.

[Vasoreactivity of normal brain tissue in cases of arteriovenous malformations--evaluation by 123I-IMP SPECT using acetazolamide]

Arteriovenous malformations (AVMs) are usually associated with diminished cerebral blood flow (CBF) in the parenchyma surrounding AVMs because of the steal phenomenon. Vasoreactivity in the parenchyma surrounding AVMs may change because of ischemia and abnormal hemodynamics. The aim of this study was to investigate vasoreactivity in parenchyma surrounding AVMs. Quantitative single-photon emission computed tomography using N-isopropyl-p-I-123 iodoamphetamine (IMP-SPECT) was performed before and after intravenous administration of acetazolamide (Diamox). Diamox is a potent cerebral vasodilator which causes tissue acidosis, and IMP-SPECT was performed 10 min after intravenous infusion of a 1g dose. The subjects were 8 patients with AVMs. The AVM was in the frontal lobe in 3 patients, the temporal lobe in 1 patient, the lateral ventricle in 1 patient, the midbrain in 1 patient, the basal ganglionic region in 1 patient, and the vein of Galen in 1 patient. A rotating gamma camera with two heads was used to perform SPECT. IMP was injected into an arm vein, and a 5-min period of blood withdrawal, 1 ml/min, was started simultaneously from a small catheter placed in the radial artery. Kuhl's method was used to quantify cerebral blood flow (CBF). Multiple contiguous 6-pixel-diameter region of interest (ROI) circles along the cerebral cortex and cerebellar hemisphere were used, and ROIs which included the AVM nidus, draining veins or infarctions were excluded from the study. Vascular territories containing arteries feeding the AVM were defined as near-ROIs on SPECT, and all other ROIs were defined as far-ROIs. (ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-1 and beta-adrenergic receptor blocking potencies of bopindolol and its two metabolites (18-502 and 20-785) as assessed by radioligand binding assay methods

1. The pKi value of bopindolol for alpha 1High-subtypes in canine aorta, rat hearts and rat brain was 5.71, 5.52 and 6.56, respectively. In addition, the pKi values of these drugs in canine aorta, rat hearts and rat brain for the alpha 1Low-subtype was very low. 2. The phenylephrine induced-contractions of aortae of guinea pigs and rats were not inhibited by these agents. 3. Both bovine hearts and tracheal smooth muscles indicated that 18-502 had the highest pKi value to beta 1- and beta 2-adrenoceptor subtypes and the rank order of these beta-blocking potencies were 18-502 > bopindolol > 20-785.

[Dysfunction of E-cadherin due to mutation of beta-catenin in a scirrhous gastric cancer cell line]

E-cadherin is a calcium dependent cell-cell adhesion molecule. In cancer tissue, detachment of the adhesion system is indispensable for invasion and metastasis of cancer cells. We have investigated mechanism of the dysfunction of E-cadherin-dependent cell-cell adhesion system in gastric carcinoma cells. Although the high expression of E-cadherin in a scirrhous gastric cancer cell line HSC-39, the function of E-cadherin was completely abolished. Western blotting of beta-catenin in HSC-39 cells demonstrated that a truncated beta-catenin was detected. The truncation was due to partial deletion of beta-catenin DNA. It was concluded that in HSC-39 loss of E-cadherin dependent cell-cell adhesion was due to mutation of beta-catenin gene.

A new mutation in exon 12 of the gp91-phox gene leading to cytochrome b-positive X-linked chronic granulomatous disease

We have previously reported a patient with cytochrome b-positive X-linked chronic granulomatous disease. Although the O2- production of neutrophils from the patient was completely defective, we presented data suggesting that the patient's cytochrome b was present at a normal level and possibly had normal spectroscopic features. Thus, to look for a mutation in the cytochrome b heavy chain (gp91-phox) gene, DNA analysis of gp91-phox cDNA derived from this patient was performed. As a result, we found that five nucleotides (1521 through 1525) within exon 12 were deleted, and a new sequence of eight nucleotides was inserted. This mutation converted Gln507-Lys508-Thr509 into His-Ile-Trp-Ala. Mismatched polymerase chain reaction showed that the mother has both wild and mutated alleles, confirming that this case was transmitted in an X-linked fashion. This mutation is different from those previously reported by others. The translocation of p47-phox and p67-phox to the membrane fraction occurred, indicating the complete formation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. We conclude that this case suggests that the structure encoded on exon 12 of gp91-phox is important for electron transfer.

[Pain management in advanced pediatric cancer patients--a proposal of the two-step analgesic ladder]

Pain treatment for 17 pediatric cancer patients in our institution was evaluated and disirable cancer pain management for children was discussed. Most of the patients (aged 1-17 years) suffering severe pain for about one month were in the advanced stage of the malignant diseases (e.g. leukemia). The pain etiology was mostly tumor-associated while therapy-related pain accounted for 23.5%. These pains were treated with NSAIDs or pentazocine before the consultation with inadequate relief. Oral morphine sulfate or continuous intravenous morphine chloride was administered to 16 patients with successful pain relief and side effects such as nausea (52.9%) and drowsiness (41.2%). It took 5.5 days on average until adequate pain control methods were determined. It is known that most NSAIDs frequently used for pediatric pain possibly cause adverse effects such as platelet dysfunction or mucous membrane injury with a suppository, which could lead to a fatal disorder in clinically ill pediatric cancer patients. Moreover sufficient doses for the pain relief are not necessarily given to the pediatric patients because of a limit to the dosage of NSAIDs. The period of pediatric cancer pain in which the patient require a methodical treatment and receive benefit from pain relief is relatively short in the advanced stage, not to mention the early stage in which chemotherapy is efficacious against cancer disease itself. Therefore, to obtain effective pain control within a short time, the authors propose the pain management for advanced pediatric cancer patients by the two-step analgesic ladder prescribing weak or strong opioid analgesics first, adapted from the three-step ladder of the WHO Cancer Pain Relief, 1986.

[Measurement of pH, time-dependent-changes in pH, [Na+], and [K+] in human tears--comparison between normal subjects, subjects with decreased tear secretion, and contact lens wearers]

In order to investigate basic mechanisms of tear secretion and tear gland dysfunction, the pH, its time-dependent change (delta pH), [Na+], and [K+] of basal and reflex tears were measured. Subjects were humans with normal tear secretion or decreased tear secretion, and hard contact lens (HCL) wearers. Reflex tears were collected by administration of distilled water into the conjunctival sacs of the fellow eyes to study the secretory function of normal human lacrimal glands. In the clinical part of this study, reflex tears were collected from subjects before and after tasting horseradish paste. The [K+] and delta pH of the normal human reflex tears were significantly higher than in the basal tears according to the degree of stimulus until medium range. This suggests the presence of K(+)- and HCO(3-)-dependent secretory mechanism in the lacrimal glands. In the patients with decreased tear secretion, [K+] data of reflex tears were either higher than or equivalent to the data for basal tears. Therefore, the difference in amplitude of the stimulus-induced increase of tear [K+] suggests that there are two or more types of lacrimal gland dysfunction in patients with decreased tear secretion.

Characteristics of choledochal cysts in neonates and early infants

Thirty-six infants with choledochal cyst consisting of 28 babies less than 12 months of age and 8 between 13 and 24 months of age, were analyzed. Characteristics of cases were as follows: (1) they were usually of the cystic type, (2) a huge abdominal mass and jaundice with alcoholic stool were typically found, (3) no symptom suggesting acute pancreatitis was observed, (4) amylase levels in bile were usually low, despite the presence of pancreatobiliary malunion, while other pancreatic enzymes in bile commonly showed a high concentration, and (5) primary cyst excision and biliary reconstruction was the treatment of choice, and could be safely performed with favorable outcomes even in babies less than 1 year of age.

The significance of PCNA and p53 protein in some oral tumors

The expression of PCNA and p53 protein was evaluated in a total of 75 cases of benign and malignant lesions of the oral cavity, comprising 50 squamous cell carcinomas (SCCs), 14 leukoplakias, and 11 pleomorphic adenomas. The DNA histogram of 20 SCCs was measured by flow cytometry. p53-positive cells were frequently seen in SCCs, but were rare in leukoplakias and pleomorphic adenomas. The PCNA labeling index (LI) was higher in SCCs than in other benign lesions. The expression rate of p53 protein was markedly elevated in SCCs obtained from smoking patients, when compared to nonsmoking patients. DNA ploidy did not show a close relationship with PCNA and p53 expression. The mean value of PCNA LI for 22 cases carrying positive p53 protein was 52.3%, which was higher than that of p53 protein negative cases (35.7%). The Kaplan-Meier survival curve of the patients who were negative for p53 was significantly more favorable than for patients who were positive for p53 (P < 0.01, Cox-Mantel test). These results suggest that PCNA and p53 LI are markers for the malignant potential of the oral mucosa, and are a useful indicator suggesting a poor prognosis.

Intratumoral regional heterogeneity of DNA ploidy patterns in colorectal carcinomas

There is no agreement on the evaluation of intratumoral DNA ploidy heterogeneity, and its clinical significance remains controversial. We categorized intratumoral ploidy heterogeneity in an effort to avoid confusion and misunderstanding among investigators. We classified the heterogeneity into 3 major types (Types A, B and C) and a combined type (Type D), based on the intratumoral distribution profiles of DNA aneuploid lines identified by flow cytometry in 52 cases of colorectal cancer with intratumoral DNA ploidy heterogeneity selected from a consecutive series. Every carcinoma examined in this study fell into one of the 4 categories: Twenty-six tumors (50%) were classified as Type A, 6 (11%) as Type B, 2 (3%) as Type C, and 18 (36%) as Type D. We discussed the mechanisms of DNA ploidy heterogeneity evolution within a tumor, and also proposed a pathway to these types of DNA ploidy heterogeneity as an aid to understanding the relationship between tumor progression and DNA ploidy changes.

Field potential change in the prefrontal cortex of the left hemisphere during learning processes of reaction time hand movement with complex tone in the monkey

Field potentials were recorded with electrodes implanted in various cortical areas while a naive monkey was learning reaction time hand movements with complex tone. When cortical surface-negative, depth-positive potential (at a latency of about 80 ms after a stimulus onset) appeared in the rostral bank of the inferior limb of the arcuate sulcus of the left cerebral hemisphere, and became gradually larger, the monkey began to respond to the stimulus with the movement. As the potential in the prefrontal (prearcuate) cortex and the cerebellar-mediated potential in the motor cortex gradually increased with further training, the movement became quicker and more skillful. Three naive monkeys achieved the movement with complex tone in shorter training days than the movement with pure tone; the movement with pure tone was not accompanied by any significant potential in the prefrontal cortex. It is deduced from the present study, and previous studies on visuo-initiated movements, that the prefrontal area, especially in the left hemisphere, plays a significant role for a monkey to associate a stimulus with appropriate motor execution.

The proto-oncogene product c-Cbl becomes tyrosine phosphorylated by stimulation with GM-CSF or Epo and constitutively binds to the SH3 domain of Grb2/Ash in human hematopoietic cells

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin (Epo) are hematopoietic growth factors that regulate proliferation and differentiation of hematopoietic cells. They elicit and control a cascade of biochemical events, the earliest of which is tyrosine phosphorylation of several cellular proteins. Grb2/Ash is composed of SH2 and SH3 domains. The SH2 domain binds to tyrosine-phosphorylated proteins, and the SH3 domains bind to proteins containing proline-rich regions. It is considered that Grb2/Ash functions as an adapter protein linking tyrosine kinases and Ras in downstream of receptors for growth factors in fibroblasts. However, the mechanisms of signal transduction through Grb2/Ash and the roles of proteins associated with Grb2/Ash remain to be determined in hematopoietic cells. By means of the binding experiments using the glutathione S-transferase fusion protein including the full-length Grb2/Ash, we have found that Shc and unidentified 130- and 135-kDa proteins are associated with Grb2/Ash and that they are tyrosine phosphorylated by treatment with GM-CSF or Epo in a human leukemia cell line, UT-7. We have purified the 130-kDa protein (pp130) using the glutathione S-transferase-Grb2/Ash affinity column. The amino acid sequence analysis of the three peptides derived from the in situ protease digestion of the purified pp130 showed that the pp130 was identical to the human c-cbl proto-oncogene product (c-Cbl). c-Cbl constitutively binds to the SH3 domain of Grb2/Ash both in vitro and in vivo but not to the SH2 domain of Grb2/Ash, and the binding of Grb2/Ash to c-Cbl or Sos was not altered by GM-CSF stimulation. Moreover, c-Cbl (pp130) becomes tyrosine phosphorylated rapidly and transiently depending on GM-CSF or Epo stimulation. These findings strongly suggest that c-Cbl is implicated in the signal transduction of GM-CSF or Epo in hematopoietic cells and that c-Cbl is involved in another signaling pathway different from the Ras signaling pathway.

[In vitro topically applied fluoroquinolone penetration into the anterior chamber]

The penetration mode of five fluoroquinolone ophthalmic solutions (OFLX, NFLX, LVFX, LFLX and CPFX) through the rabbit cornea was examined with an in vitro experimental system. The system was an artificial anterior eye segment model made of acrylamide covered with a New Zealand albino rabbit cornea with a scleral flap. In vivo studies on the penetration of OFLX and NFLX ophthalmic solutions into the anterior chamber of albino rabbits were performed separately. Parameters gained from in vivo pharmacokinetic analysis and those from the model eye were compared. The permeability coefficients (K) (cm/s) through the cornea and partition coefficient were 6.95 x 10(-7) cm/s in LVFX, 6.78 x 10(-7) cm/s in OFLX, 3.58 x 10(-7) cm/s in LFLX, 2.46 x 10(-7) cm/s in CPFX and 0.06 x 10(-7) cm/s in NFLX, and 0.24, 0.23, 0.14, 0.06 and 0.07, respectively. High correlation was seen between the corneal permeability coefficients, and the partition coefficient Cmax of OFLX obtained from the in vivo study was higher than that of NFLX. The applied experimental system would be a useful tool for the estimation of the in vivo Cmax of the examined drug.