Two-step hard acid deprotection/cleavage procedure for solid phase peptide synthesis

A new two-step deprotection/cleavage procedure for t-butoxycarbonyl (Boc) based solid phase peptide synthesis is reported. First the protective groups are removed from 4-(oxymethyl)-phenylacetamidomethyl (PAM) resin attached peptide with the weak hard acid, trimethylsilyl bromide-thioanisole/trifluoroacetic acid (TFA). In the second step, the peptide is cleaved from the resin with a stronger hard acid such as trimethylsilvl trifluoromethanesulfonate in TFA or with HF. The method is also shown to deformylate Nⁱⁿ-formyltryptophan moiety efficiently. The usefulness of this procedure for practical solid phase peptide synthesis is demonstrated by comparison with other deprotection methods in the synthesis of urotensin II and human endothelin.     

High-performance Liquid Chromatographic Determination of Trazodone and 1-m-Chlorophenylpiperazine with Ultraviolet and Electrochemical Detector

A high-performance liquid chromatographic (HPLC) assay was developed for the determination of trazodone and its metabolite, 1-m-chlorophenylpiperazine (m-CPP), in plasma. The high level of trazodone in plasma was detected by ultraviolet absorbance at 254 nm and the low level of m-CPP in plasma was detected by coulometric electrochemical detection at 840 mV on the series arrangement of two detectors. Pilsicainide as an internal standard for both compounds was monitored by both detectors. Trazodone and m-CPP in plasma were extracted by a rapid and simple procedure based on CN bonded-phase extraction, and C₈ reversed-phase HPLC separation. Determination was possible for trazodone in the concentration range 100–2000 ng mL^?1 and for m-CPP in the concentration range 5–100 ng mL^?1. The recoveries of trazodone and m-CPP added to plasma were 81·0–84·2 and 68·0–73·2%, respectively, with coefficients of variation of less than 7·3 and 8·2%, respectively. The method is applicable to high level monitoring of trazodone and low level monitoring of m-CPP in plasma of healthy volunteers and patients treated with trazodone.     

Keratinocyte growth factor is an endogenous stimulant of rabbit gastric epithelial cell proliferation and migration in primary culture

Mesenchymal-epithelial interactions are important in the gastric mucosal repair. However, specific factors responsible for such interactions have not been established. In the present study, keratinocyte growth factor (KGF) significantly stimulated proliferation of gastric epithelial cells dose dependently and synergistically with hepatocyte growth factor (HGF), epidermal growth factor (EGF) and insulin. Restitution of gastric epithelial monolayers was also assessed, using a round wound restitution model. Keratinocyte growth factor facilitated the restitution of gastric epithelial cells significantly but did not have any effects on gastric fibroblasts. Keratinocyte growth factor receptor mRNA was expressed by gastric epithelial cells, indicating that these effects were elicited by the specific receptor mediated pathway. Northern blot analysis revealed the expression of KGF mRNA in gastric fibroblasts but not in gastric epithelial cells, indicating the production of KGF. These results suggest that KGF might be involved in gastric mucosal repair, through mesenchymal-epithelial interaction.     

The serum pregnancy-specific β1-glycoprotein to betahuman chorionic gonadotrophin ratio as an index of prognosis in patients with choriocarcinoma

Summary. The ratio of serum pregnancy-specific β₁-glycoprotein (SP1) to the β-subunit of human chorionic gonadotrophin (β-hCG) before and after chemotherapy was measured in 12 patients with metastatic choriocarcinoma. The ratios before chemotherapy ranged between 0^.03 and 0^.75, with a mean value of 0^.34 (SD 0^.21). The ratio increased to over 1^.0 (1^.05–53^.3) after one or two courses of chemotherapy in seven of the 12 patients. These women achieved complete remission. In the other five patients who died of the disease due to drug resistance of the tumour, the ratio after chemotherapy was low (0^.04–0^.74) and tended to decline. These data suggest that the serum SPl/β-hCG ratio can be used to predict the prognosis of patients with choriocarcinoma.     

Adjuvant Immunotherapy for Malignant Brain Tumors

New methods of adjuvant immunotherapy were introduced for thetreatment of malignant brain tumors. Allogeneic bone marrowcell transfusion or local intratumoral infusion of allogeneicor autologous peripheral white blood cells were conducted on18 patients having malignant glioma, after ordinary treatmentof operation, radiation or chemotherapy. The survival rate ofthese patients was significantly prolonged when compared withthe rate normally expected. No side effects were noted. Morphologicalchanges of cells in the cerebrospinal fluid taken from the intratumoralcavity, before and after infusion of peripheral white bloodcells, were studied. Cytolysis and phagocytosis of tumor cellsby macrophages were observed. Suppressive mechanism of immunologicallycompetent cells on glioma cells was partly studied, cytologicallyin vitro.     

STUDIES ON RACEMIZATION DURING COUPLINGS USING A SERIES OF MODEL TRIPEPTIDES INVOLVING ACTIVATED RESIDUES WITH UNFUNCTIONALIZED SIDE CHAINS

Racemization studies have been carried out using as model tests couplings of N-benzyloxycarbonylglycyl-l -χ with benzyl N^e-benzyloxycarbonyl-l -lysinate followed by deprotection and analysis for the diastereomeric tripeptides with an amino acid analyzer, for χ = alanine, leucine, phenylalanine, valine and isoleucine. The order of susceptibility to racemization of residues during these segment couplings depends on whether the solvent is polar or apolar, with isoleucyl and valyl, followed by phenylalanyl, being the most susceptible ones in polar solvents. The racemization depressing effect of some additives on carbodiimide-mediated couplings has been examined. Reconciliation of apparent discrepancies in data in the literature on the relative merits of l-hydroxy-benzotriazole and N-hydroxysuccinimide is made on the basis of the nature of the model tests used in acquiring the data.     

Reduced shear stress and disturbed flow may lead to coronary aneurysm and thrombus formations

BACKGROUND: With Kawasaki disease it is important to clarify the mechanisms of coronary artery aneurysm and thrombus to avoid acute myocardial infarction. The authors tested the hypothesis that shear stress is reduced at coronary branching sites and in coronary artery aneurysms, and that this reduction of shear stress can promote formation of coronary artery aneurysms and thrombus. METHODS: The subjects were 111 children with Kawasaki disease with left coronary artery aneurysms, classified into three groups: giant coronary artery aneurysm (n= 28, diameter of coronary artery >8 mm), aneurysm (n= 44, diameter of coronary artery =8 mm), and normal-appearing coronary (n= 39). Averaged peak flow velocity (APV), flow patterns and shear stress were measured and calculated at normal-appearing coronary vessels, left coronary artery branching sites and intra-coronary aneurysm using flow wire, and coronary angiography. Also, presence and appearance of thrombus were detected by intravascular ultrasonography. RESULTS: The authors found that 90.3% of the coronary artery aneurysms occurred at major left coronary branching sites. APV and shear stress were significantly decreased in giant coronary artery aneurysms (APV, 7.1 +/- 2.1 cm/s; shear stress, 3.8 +/- 2.1 dyne/cm(2)) and at the left coronary artery branching site (APV, 9.1 +/- 1.2; shear stress, 1+/-+/-.2 3.0). In total, 20 of 24 thrombi were detected only in giant aneurysm, and all patients exhibited disturbed flow pattern in their giant coronary artery aneurysms. CONCLUSIONS: Reduced shear stress and disturbed flow pattern may lead to coronary artery aneurysm and thrombus formation.     

A Biodegradable Poly-l-lactic Acid Coronary Stent in the Porcine Coronary Artery

Although biocompatibility of biodegradable stents is controversial, stents made of high molecular weight poly- l -lactic acid (PLLA) are thought to be the most promising. We investigated the biocompatibility of PLLA stents histologically and angiographically in porcine coronary arteries. The Igaki-Tamai stent is made of PLLA monofilaments (molecular mass 183 kD) with a zigzag helical coil design. Fourteen PLLA stents in 6 pigs and 9 Palmaz-Schatz half stents in 9 pigs were implanted in 15 normocholesterolemic pigs. Stents were mounted on a delivery catheter, and were implanted percutaneously into coronary arteries. Coronary angiography was performed before and immediately after stenting, at 2 and 6 weeks in five PLLA pigs and nine Palmaz-Schatz pigs. Histological studies were performed in PLLA pigs: 2 pigs at 2 weeks, 3 pigs at 6 weeks, and 1 pig at 16 weeks with hematoxylin-eosin and elastica van Giesons stains. All PLLA stents were successfully delivered. No stent thrombosis was detected in either group. There were no significant differences in minimal lumen diameter (MLD) or percent diameter stenosis between the PLLA and Palmaz-Schatz stent groups immediately after implantation, or at 2 or 6 weeks after implantation. Histological studies at 2, 6, and 16 weeks revealed no inflammation and minimal neointimal coverage on the PLLA stent struts. The PLLA stent maintained its structure for up to 16 weeks. These results suggest sufficient biocompatibility and strength of PLLA biodegradable stents in porcine coronary arteries. Clinical trial is now underway to validate the safety and usefulness of PLLA stents in humans.     

Experimental and Clinical Studies of Biodegradable Polymeric Stents

The metallic stent has become the most common device to reduce acute occlusion and late restenosis after balloon angioplasty, but the long-term effects of metallic stents in human coronary arteries are still unknown. To overcome several problems of conventional stenting, there have been many attempts to manufacture stents made of biodegradable materials. Although some studies have noted various degrees of inflammatory responses after biodegradable stent implantation, stents made of poly-1-lactic acid (PLLA) showed high biocompatibility with minimal inflammatory response and neointimal formation in porcine coronary arteries. A clinical study of PLLA self-expanding stent implantation is underway in Japan. The initial and 6-month results are favorable and suggest the feasibility, safety, and efficacy of the PLLA biodegradable stent in humans. However, long-term follow-up with larger numbers of patients will be required to validate the long-term efficacy of PLLA stents.     

Development of Gastroesophageal Varices and Risk of Variceal Bleeding in Patients With Cirrhosis

Abstract: We studied the relationships between portal pressure measured using the portal venous pressure gradient, the development of gastroesophageal varices, and the risk of variceal bleeding in 56 patients with cirrhosis. Portal pressure was higher in patients with varices than in those without (P>0.01), and 11 mmHg was the lowest portal pressure measured in the patients with varices. The size of the varices was not associated with the portal pressure. There was no difference in the value of portal pressure measurements for the patients with variceal bleeding and those without and there was no linear-relationship between the degree of portal hypertension and the rate of variceal bleeding. 12 mmHg was the lowest portal pressure measured in the patients with variceal bleeding. The size of the varices was related to the rate of variceal bleeding (P>0.05). We conclude that (a) a portal pressure of 11 mmHg is necessary for the formation of varices, (b) 12 mmHg of portal pressure is necessary for variceal bleeding to occur but the degree of portal hypertension has no predictive value for the risk of variceal bleeding, and (c) the size of the varices does not depend on the degree of portal hypertension but is associated with the risk of variceal bleeding.