A novel C-type lectin regulating cell growth, cell adhesion and cell differentiation of the multipotent epithelium in budding tunicates

We have isolated two Ca2+-dependent, galactose-binding polypeptides from the budding tunicate, Polyandrocarpa misakiensis. Based on their partial amino acid sequences, full-length cDNAs were cloned. One of them was identical with a tunicate C-type lectin (TC14-2) reported previously. The other was a novel C-type lectin, referred to as TC14-3. In living animals, they appeared to be coupled. This complex of lectins, when applied in vitro to tunicate multipotent cells of epithelial origin, blocked cell proliferation and induced cell aggregation. The aggregates expressed a homolog of the integrin α-chain and other differentiation markers specific for epithelial cells. Recombinant TC14-3 could reproduce all the activities of native lectins by itself, which was accelerated by recombinant TC14-2. The inhibitory activity of TC14-3 on cell growth was completely abolished by the addition of 50 μM D-galactose. Anti-TC14-3 monoclonal antibody showed that the antigen was expressed constitutively by the multipotent epithelial and mesenchymal cells. These results provide evidence that in P. misakiensis a C-type lectin plays a novel, cytostatic role in regulating cell growth, cell adhesion and cell differentiation during asexual reproduction.

DIC-CT findings of biliary cystadenocarcinoma communicating with the bile duct: a case report

Among the intrahepatic cystic diseases except Caroli's disease, only biliary cystadenoma/cystadenocarcinoma may communicate with the bile duct. We present a case of biliary cystadenocarcinoma in which drip infusion cholangiographic-computed tomography demonstrated communication between an intrahepatic cyst and the biliary system preoperatively. Drip infusion cholangiographic-computed tomography, a simple and noninvasive examination, is useful for differentiating biliary cystadenoma/cystadenocarcinoma from other intrahepatic cystic lesions.

VUF-K-8788, a periphery-selective histamine H1 antagonist with anti-pruritic activities

The pharmacological properties of 7-[3-[4-(2-quinolinylmethyl)-1-piperazinyl]-propoxy]-2,3-dihydro-4H-1,4-benzothiazin-3-one (VUF-K-8788) were investigated in vitro and in vivo. VUF-K-8788 inhibited [3H]-mepyramine from binding to the cell membrane of lung parenchyma (Ki value: 5.0 nM) and the histamine-induced contraction of isolated guinea pig ileum (pA2: 9.71) without affecting ileal contractions induced by acetylcholine, serotonin, KCl and BaCl2. The increase of vascular permeabilities induced by histamine and passive cutaneous anaphylaxis (PCA) in guinea pigs were inhibited by VUF-K-8788 in a dose-dependent fashion (ED50: 0.24 and 0.26 mg/kg, p.o., respectively). Moreover, the anti-histaminic effect of VUF-K-8788 was also observed in rats. In experiments on the effects on the central nervous system, VUF-K-8788 at 1 mg/kg, p.o. hardly antagonized the H1 receptor at all in the cerebral cortex of guinea pigs. VUF-K-8788 inhibited the PCA-induced scratching behavior completely without affecting thiopental-induced sleep in mice. These results suggested that VUF-K-8788 would be useful in the treatment of allergic disorders such as atopic dermatitis and eczema.

Biliary cystadenocarcinoma with superficial spread to the extrahepatic bile duct

We report a case of biliary cystadenocarcinoma of the liver with superficial spread to the extrahepatic bile duct. Preoperative endoscopic retrograde cholangiography revealed communication between a 4.5-cm cyst in segment 4 of the liver and the bile duct. From the findings obtained by peroral cholangioscopy and intraoperative cholangioscopy, the granular mucosa in the bile duct was diagnosed as superficially spreading cancer. The right posterior segmental bile duct and the right anterior segmental bile duct were resected at the point where the spread of cancer was no longer traceable and left lobectomy plus caudate lobectomy was carried out. This achieved radical resection, leaving the resected margin of the bile duct free from cancer. Histopathologically, well-differentiated papillary adenocarcinoma was found on the inner surface of the cyst, and the cancer had superficially spread from the cyst to the extrahepatic bile duct via the 2.5-mm diameter communication between the cyst and bile duct. The cancer was limited only to the mucosal layer all over the lesion. When performing radical surgery for biliary cystadenocarcinoma, it is recommended that cholangioscopy be performed to examine whether the cancer has superficial spread to the extrahepatic bile duct or not. Bile duct resection should be carried out, depending on the extent of the superficial spread, so that the resected margin of the bile duct is free from cancer.

Cranial chordomas in infancy and childhood. A report of two cases and review of the literature

Cranial chordomas are uncommon, accounting for less than 1% of all intracranial neoplasms. Although they are presumed to arise from congenital notochordal remnants, it is rare for these tumors to present in childhood. Only 35 cases of cranial chordomas have been reported in children 16 years of age or younger. We report 2 additional cases of pediatric cranial chordomas. One occurred in a 4 month old infant and to our knowledge represents the earliest age of presentation yet reported. The second case documents the value of MR imaging in delineating the extent of the tumor and defining its relationship to adjacent structures.

Inactivate the remaining p53 allele or the alternate p73? Preferential selection of the Arg72 polymorphism in cancers with recessive p53 mutants but not transdominant mutants

Several reports have noted epidemiological differences in the prevalence or prognostic significance of p53 mutants with arginine (R) or proline (P) at the codon 72 polymorphism (R72/P72) in certain cancer types, but the biological significance of these variants is unclear. The ability of p53 mutants to interact with and inactivate the p53 homolog p73 was recently reported to depend on the conformational state of the p53 protein and the residue at codon 72. Since the conformation of p53 mutants may influence their ability to transdominantly inhibit wild-type p53, we tested whether there was a correlation between the amino acid at codon 72 and the transdominance of p53 alleles found in tumors. The transdominance test was performed using a simple yeast transcription assay, and the amino acid at codon 72 was determined by sequencing. A total of 100 p53 mutants were tested. Compared with the germline frequency (R:P = 427:297), an extreme bias in favor of the R72 allele was observed with recessive mutants (R:P = 50:7, P < 0.0002), whereas no selection for the R72 allele was seen with transdominant mutants (R:P = 23:20). p53 and p73 are known to transactivate overlapping sets of target genes. We interpret the R72 bias with recessive mutants as evidence that decreased activation of p53 target genes provides a selective growth advantage to tumor cells during the stage of tumorigenesis in which a wild-type and mutant p53 allele coexist. We suggest that transdominant p53 mutants achieve this by inactivation of the remaining wild-type p53 allele, whereas recessive p53 mutants achieve it through inactivation of p73.

Symptomatic solitary xanthogranuloma occupying the cavernous sinus. Case report

The authors report the first case of a solitary xanthogranuloma of the cavernous sinus without systemic manifestation. A 43-year-old woman experienced decreased visual acuity on the right side in association with papilledema and a visual field defect. She was alert and no other neurological sign was observed. She had no family history of hyperlipoproteinemia and no cutaneous and/or systemic xanthomatous lesions. Skull x-ray films showed an enlarged right superior orbital fissure. Computerized tomography revealed a low-density oval mass 2 x 3 cm in diameter in the right cavernous region that was compressing the right optic nerve in the lateral to medial direction. This mass exhibited isointensity on T1-weighted and mixed-pattern hyperintensity on T2-weighted magnetic resonance images with diffuse contrast enhancement. Cerebral angiography demonstrated fine staining in the margin, originating from the right middle meningeal artery. These neuroimaging findings closely mimicked those associated with trigeminal neuroma. The lesion was partially removed via a right-sided zygomatic approach, and her symptoms improved. Clinical characteristics and histopathological features of this rare case are discussed.

Cost-effectiveness associated with the diagnosis and staging of non-small-cell lung cancer

OBJECTIVE

We evaluated how much time and money could be saved without compromising overall results in treating lung cancer.

SUBJECTS AND METHODS

We retrospectively evaluated 318 patients for T- and M-factors and 335 for N-factor. If bronchoscopy failed to diagnose a mass lesion believed to be malignant in x-ray computed tomography (CT), we proceeded to direct thoracotomy without needle or video-assisted biopsy. When mediastinal nodes were negative in CT, we proceeded to direct thoracotomy without mediastinoscopy. We searched routinely for distant metastasis with brain and abdominal CTs and bone scans.

RESULTS

Lesions suspected of malignancy in CT were pathologically malignant in 93%. A total of 82.8% of patients with CT-negative mediastinum were without metastasis. The remainder, with metastasis, had a postoperative 5-year survival of 23.5%. Brain CT scans were positive in only 2.2%, abdominal CT scans in 2.4%, and bone scans in 5.0%, for patients with a cT1/T2 non-cN2 lesion.

CONCLUSION

Brain and abdominal CT scans and bone scans may be omitted for cT1/T2 and non-cN2 lesions in CT. CT-negative mediastinum then leads to direct thoracotomy. The vast majority of patients may thus undergo surgery earlier with less physical and financial burden. The cost saving was calculated to be 59.4% per cT1/T2 non-cN2 patient, or US$666,815, for population evaluated based on cost-effectiveness.

An occipital encephalocystocele involving both sides of the lateral ventricles

We reported a rare case of an occipital encephalocystocele linked by bilateral posterior horns of the lateral ventricles. The subject was a newborn girl with a large occipital cephalocele (6 x 9 cm in diameter) covered with alopetic skin. Cerebrospinal fluid leakage was not observed. The fontanel was soft, but a characteristic flat forehead was noted. Neither neurological deficits nor cardiopulmonary dysfunctions were evident at birth. Magnetic resonance images revealed that the sac contained the occipital lobes and that the cavity was linked by bilateral posterior horns. Agenesis of the corpus callosum and dysgenesis of the falx cerebri were associated. Fifteen days after birth, the cephalocele was removed surgically. Cutting sections revealed that the cephalocele contained enlarged bilateral posterior horns and cerebral hemispheres. The postoperative course was uncomplicated by hydrocephalus or infection, and the patient was discharged without any neurological deficit 22 days after surgery. Her milestone was survival; and at present 12 months after surgery, she is alive with moderate developmental retardation.

Primary aldosteronism in pregnancy

Aldosteronism is a rare complication of pregnancy. We report a case of a 26-year-old woman who became pregnant soon after a diagnosis of primary aldosteronism due to left adrenal adenoma was made. Only oral potassium supplementation was required in addition to routine prenatal care until 36 weeks' gestation. Subsequently, antihypertensive medication was needed to control elevated blood pressure. A healthy male infant was delivered by cesarean section because of abruptio placentae. The postoperative course was uneventful. Left adrenalectomy was conducted eight months after delivery under laparoscopic visualization. In this case report, we discuss management of aldosteronism in pregnancy and review the literature.

[A case of Sjögren's syndrome and systemic sclerosis complicated with acute pancreatitis]

We report a case of Sjögren's syndrome (SS) and systemic sclerosis (SSc) complicated with acute pancreatitis. A 51-year-old woman had been diagnosed as SS in 1973. She noticed Raynaud's phenomenon in 1977. In 1988, interstitial pneumonia (IP) was pointed out and she was treated with methylprednisolone (mPSL) pulse therapy. Prednisolone (PSL) was gradually tapered to 3-5 mg daily and she visited our outpatient clinic in 1995. On her first admission to our hospital in 1996, she showed xerostomia, keratoconjunctivitis sicca, sclerotic skin changes of her distal extremities and face, thickening of her sublinguinal frenulum, and regurgitative esophagitis. She was positive with anti-SS-A and SS-B antibodies. She was diagnosed as SS and SSc. Radiographic and laboratory data also established the diagnosis of inactive IP, renal tubular acidosis (RTA) and chronic renal failure (CRF). In April 30th 1997, she was admitted to our hospital again with complaints of dyspnea, dysesthesia, epigastralgia and petechia. Active IP and mononeuritis multiplex were diagnosed, and petechia was considered to be associated with vasculopathy. Her serum amylase level was 891 mU/ml on admission and spontaneously increased to 2440 mU/ml on May 12th along with increase of fibrinogen degradation product, D-dimer and alpha 2 plasmin-plasmin inhibitor complex levels. Ultrasonography depicted swelling of her pancreatic head and the diagnosis of acute pancreatitis was made. She was treated with protease inhibitors and intravenous hyperalimentation for acute pancreatitis. mPSL pulse therapy (500 mg/day for 3 days) was instituted for IP and mononeuritis multiplex on May 22, followed by 50 mg of daily PSL. While IP and mononeuritis multiplex gradually improved by the high-dose steroid therapy, serum amylase level raised to more than 4293 mU/ml, suggesting the modification of pancreatitis by the treatment with steroid. Since she did not respond to the conservative therapy for acute pancreatitis, she was treated with plasmapheresis, which turned out to be very effective. However, she was suffered from fungal pneumonia and died of respiratory failure. As far as we know, only three cases of SS with acute pancreatitis have been reported so far. The immunopathological mechanisms of development of acute pancreatitis in our case, especially focusing on the significance of microvasculopathy and hypercoagulability, were discussed.

Partial hepatectomy of marmoset: clinical and pathological effects and utility in microsomal enzyme analysis

Liver biopsy based on a partial hepatectomy technique (shearing) was performed in 10 common marmosets (Callithrix jacchus). This is a preliminary study to evaluate the effects of drugs on hepatic microsomal enzymes: cytochrome P-450 and T4 uridine diphosphate glucuronyl transferase (T4-UDPGT), by comparing post-treatment values with pre-treatment values individually with a limited number of animals. The effects of the biopsy on clinical findings and liver pathology were evaluated during the first 5 post-surgical weeks. Although the plasma aspartate aminotransferase (AST) activities tended to decrease from 1 to 4 weeks post-surgery, no abnormality was noted in clinical sign, body weight, the hematocrit value or other blood chemical values. At necropsy, adhesion of the sheared site of the liver to the parietal peritoneum or the small intestine was evident in 2 of the 4 marmosets. Microscopic examination revealed focal fibrosis in the liver, but it was localized around the sheared site. Based on the above results, it was concluded that liver biopsy must be performed more than one month before administration of the drug to be tested. The biopsy samples and the whole liver samples obtained at autopsy were subjected to analysis of microsomal protein content, cytochrome P-450 content and T4-UDPGT activity. In comparison with the values from the whole liver samples, those from the biopsy samples showed no significant difference. Furthermore, there was a significant correlation rather than difference between matched values. This suggested that partial hepatectomy is a useful method for obtaining pretreatment values in liver biochemistry to evaluate the effects of drug-treatment in individual animals.

Malaria infection induces rapid elevation of the soluble Fas ligand level in serum and subsequent T lymphocytopenia: possible factors responsible for the differences in susceptibility of two species of Macaca monkeys to Plasmodium coatneyi infection

The intraerythrocytic stage of the simian malaria parasite Plasmodium coatneyi (CDC strain) was intravenously inoculated into two species of macaques with different susceptibilities to infection with this parasite, including four Japanese macaques (Macaca fuscata) and three cynomolgus macaques (M. fascicularis). The Japanese macaques infected with P. coatneyi developed severe clinical manifestations similar to those of severe human malaria and eventually became moribund, while the infected cynomolgus macaques, natural hosts of the parasite, exhibited no severe manifestation of disease except anemia and finally recovered from the infection. In the infected Japanese macaques, peripheral CD4(+) and CD8(+) T-cell populations were markedly decreased and fragmentation of chromosomal DNA in peripheral blood mononuclear cells was detected during the terminal period of infection, suggesting that apoptotic cell death was responsible at least in part for the T lymphocytopenia. Furthermore, soluble Fas ligand levels in sera of the infected Japanese macaques increased gradually to a markedly high level of 28. 83 +/- 10.56 pg/ml (n = 4) when the animals became moribund. On the other hand, none of the infected cynomolgus monkeys exhibited either T lymphocytopenia or elevated soluble Fas ligand level. These findings suggest that differences in immune response between the two species of macaque tested accounted for the contrasting outcomes after infection with the same isolate of malarial parasite, and in particular that a profound T lymphocytopenia due to Fas-derived apoptosis played a role in the fatal course of malaria in the infected Japanese macaques.

Results from surgical treatment for thymoma. 43 years of experience

OBJECTIVE

The biological behavior of thymoma and its prognosis after surgical intervention remain still controversial. The efficacy of surgical treatment for thymoma was investigated by examining long-term follow-up data.

SUBJECTS AND METHODS

Follow-up data for patients undergoing surgical resection of histopathologically-confirmed thymoma between 1954 and 1997 were obtained and were retrospectively analyzed. Clinical staging was based on Masaoka's staging system, and histological classification on Rosai's proposed criteria.

RESULTS

Data for 140 patients were collected. Sixty-four patients had stage I, 32 had stage II, 28 had stage III, and 16 had stage IV thymoma. There were significant differences in survival between patients with stage I and stage III, stage I and stage IV and stage II and stage III disease, but not between those with stage I thymoma and stage II thymoma. No significant difference in survival was observed between the 56 patients with myasthenia gravis (MG) and the 84 without MG. The 38 patients classified as having a predominantly-epithelial thymoma had a poorer prognosis than the 41 with a predominantly-lymphocytic thymoma. Until 1975, there were four patients with stage I thymomas who later showed recurrence, compared with 21 among those with stage II, III and IV diseases. Since 1976, extended thymectomy with thymomectomy under median sternotomy has been adopted as the standard operation for a thymoma, and there has been no recurrence in stage I patients.

CONCLUSIONS

Patients with stage III or IV invasive thymoma have a poorer prognosis and a higher recurrence rate than those with encapsulated thymoma, and patients with a predominantly-epithelial thymoma have a poorer prognosis than those with a predominantly-lymphocytic thymoma. Extended thymectomy with thymomectomy under median sternotomy can be considered as adequate treatment for a stage I thymoma. Myasthenia gravis does not appear to affect the prognosis of patients with a thymoma.

Femoral bone density and changes therein associated with differing histories of pregnancy and lactation in aged rats

OBJECTIVE

To examine the effect of prior pregnancy and lactation on bone density in aged rats.

MATERIALS AND METHODS

2 month-old female Fischer-344 rats were divided into 4 groups: 1)13 rats were allowed to get pregnant and to nurse their offspring for two or three cycles; 2)14 rats were allowed to get pregnant two or three times and were immediately separated from their young after each delivery prior to lactation; 3)10 rats were not allowed to become pregnant; and 4)7 rats were sacrificed at the beginning of the experiment. All rats were fed ad libitum. After the rats had completed two or three pregnancies with or without subsequent lactation, all were fed a restricted diet until they were 25 months old (aged rats). Then they were sacrificed and both femurs were removed from each rat. One bone was used for analysis of mineral content and the other bone was used for photodensitometry of the diaphysis.

RESULTS

31 rats (83.8% ) survived until they were sacrificed. The femurs of the aged rats showed increased ash weight compared to those of 2 month-old rats. Aged rats with prior pregnancies with or without subsequent lactation had higher femoral ash weight than those without prior pregnancies. There were no differences among aged rats in regard to marrow diameter, bone diameter, cortical width or bone density of the diaphysis in femur by photodensitometry.

CONCLUSION

In aged rats, past pregnancies but not lactation were related to increases in bone density of the femur.

[Management after hepatectomy of colorectal cancer metastases to the liver--intrahepatic arterial infusion chemotherapy and repeated hepatectomy]

Before Dec. 1993, we resected 17 patients with hepatic metastases from colorectal cancer. Hepatic recurrences developed in 82% patients who had been given mitomycin C or doxorubicin by hepatic-artery. The one-, 3- and 5-year survival rate after surgery was, 88%, 18% and 12%, respectively. Therefore, some new types of adjuvant therapy were needed to improve survival after surgery. This is a retrospective study to determine whether preventive intrahepatic artery infusion chemotherapy (HAI) and repeated hepatectomy are of benefit for patients with hepatic metastases from colorectal cancer who underwent hepatectomy. Thirty-five patients with hepatic metastases from colorectal cancer underwent hepatectomy and were administered 1,500 mg of 5-FU 10 times via the hepatic artery for 5 hrs every 1-2 weeks to prevent hepatic recurrence after Jan. 1994. Nine patients underwent repeated hepatectomy, then HAL following the operation. Non-resectable recurrence were treated by HAI. The amounts of the infused 5-FU dose were 8.5-46.5 g (mean 23 g) and 17-31 times HAI (mean 22 times). Survival rates were 81, 67, 67% and 24%, respectively, after 1, 2, 3 and 4 years. Hepatic disease-free interval rates were 49.3% and 32.5%, respectively, after 1 and 2 years. Preventive HAI could not control hepatic recurrence but prognosis after hepatectomy was improved by these modalities compared with treatment before Dec. 1993. Survival rates of 9 patients who underwent repeated hepatectomy were 89, 89% and 37%, respectively, after 1, 3 and 4 years. The prognosis of patients with hepatic metastases from colorectal cancer was improved by HAI and repeated hepatectomy, but further studies should be undertaken to improve preventive HAI.

[A case of microscopic polyangiitis with severe cardiac and respiratory muscle involvement]

A 66-year-old female was admitted to our hospital in January, 1998, complaining of low grade fever and muscle weakness of her legs. Physical examination revealed muscle weakness of her neck (4/5) and proximal skeletal muscles of her bilateral legs (3/5-4/5). She showed proteinuria and microhematuria. Her serum levels of ureanitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase, creatinekinase, aldolase and myoglobin were all within the normal ranges. Antinuclear antibodies were negative, but her serum levels of pANCA (743 EU) and C reactive protein (18.0 mg/dl) were elevated. Neuroconduction velocity of her left common peroneal nerve was decreased to 40.8 m/sec and electric myograph showed neurogenic changes. Magnetic resonance images (MRI) of her bilateral thigh depicted high signal intensity in quadriceps by T 2 weighed images, but the signals were not enhanced by gadolinium injection. Muscle and renal biopsies revealed necrotizing vasculitis of the small arteries. Crescentic glomerulonephritis was also observed by renal biopsy. These findings supported the diagnosis of microscopic PN. On 16 th admission day, she developed acute cardiac and respiratory failures due to cardiac and respiratory muscle involvements with PN, and was assisted by mechanical ventilation. She was treated with methylprednisolone pulse therapy (500 mg/day, three consecutive days) on 18 th admission day, followed by 40 mg of oral prednisolone daily. However, her symptoms deteriorated, and herserum creatinine levels increased to 2.4 mg/dl. On 24 th admission day, intravenous cyclophosphamide pulse therapy (500 mg/day) was instituted. Her cardiac wall motion on echocardiography and serum creatinine levels gradually improved, but her skeletal and respiratory muscle weakness did not improve. On 38 th admission day, she was complicated with respiratory infection by methicillin resistant Staphylococcus aures. On 62 th admission day, she died of endotoxic shock. This is the first report describing respiratory muscle involvement with PN, and the second report describing MRI findings of muscle involvement by PN. Therefore, our case provides important clinical information for the diagnosis and treatment of the disease.

[A case of renal capsular leiomyoma]

A 50-year-old woman was admitted for the treatment of retroperitoneal tumor. Enhanced comtuted tomography showed a low density mass between the left kidney and psoas muscle. Magnetic resonance imaging revealed a high intensity and homogeneous mass on T1-weighted sequence, and a low intensity and heterogeneous mass on T2-weighted sequence. Surgical exploration revealed that the tumor was adherent to the left kidney and en bloc excision of the tumor and the left kidney was performed. Histopathological diagnosis was leiomyoma originating from the renal capsule.

Management of severe acute pancreatitis with a somatostatin analog in a patient undergoing surgery for dissecting thoracic aneurysm: report of a case

A patient who was admitted to our hospital to undergo surgery for a dissecting thoracic aneurysm suffered preoperatively from severe acute pancreatitis with pancreatic pseudocysts. Computerized tomography (CT) demonstrated the presence of new fluid collection around the cyst with the absence of pancreatic necrosis. He was given a somatostatin analog (sandostatin), which was effective in decreasing the abdominal symptoms, leukocyte counts, and the serum C-reactive/protein level. A CT scan revealed that the pancreatic pseudocyst and peripancreatic fluid collection had disappeared. Although somatostatin has been reported to be ineffective for acute pancreatitis with necrosis, pancreatitis without necrosis may regress after treatment with sandostatin. This is probably due to its suppressive effect on the exocrine function, thus resulting in a decrease of pancreatic juice infiltration.

Preparation of nanoparticles consisted of poly(L-lactide)-poly(ethylene glycol)-poly(L-lactide) and their evaluation in vitro

This study describes the preparation and the evaluation of biodegradable poly(L-lactide)-poly(ethylene glycol)-poly(L-lactide) copolymer (PLA-PEG-PLA) nanoparticles containing progesterone as a model drug. PLA and PLA-PEG-PLA copolymers, whose PEG content ranged from 5.2 to 25.8% (w/w), were polymerized in our laboratory. PEG with weight-average molecular weight (Mw) 6600 or 20 000 was introduced as a hydrophilic segment into a hydrophobic PLA homopolymer. A solvent evaporation method was used to prepare the nanoparticles. The drug trapping efficiencies were around 70% and the weight-averaged mean diameters of the nanoparticles were less than 335 nm. The amount of drug released increased as the PEG content and Mw of PLA-PEG-PLA copolymers increased and the total Mw of copolymers of nanoparticles decreased. The initial burst of drug release was reduced by removing the low Mw fraction from the polymer. During the release test, both the extent to which the copolymers were degraded and the size of the nanoparticles were increased slightly by increasing the content of PEG in the polymers. Drug release from the nanoparticles could potentially be controlled by changing the PEG content, PEG Mw and total Mw of the copolymer. The molecular weight distribution (Mw/Mn, Mn: number-average molecular weight) of copolymers was also an important factor for controlled release.