Interfacial properties of self-reinforced composite poly(methyl methacrylate)

The authors describe ten years of experience in breast reconstruction in the Department of Plastic and Reconstructive Surgery in the District Hospital of Santarém--Portugal. Ninety-nine patients were treated with 106 reconstructions, most of these were immediate and some were delayed. The authors were interested in providing an adequate volume, but also into obtaining an acceptable aesthetic result. This contributes considerably to the psychological recovery of the patients.     

Conformational behavior of the HAV-VP3(110-121) peptidic sequence and synthetic analogs in membrane environments studied by CD and computational methods

The present study was undertaken to examine the structural features that may be important to explain the immunogenicity of the (110-121) peptide sequence (FWRGDLVFDFQV) of VP3 capsid protein of hepatitis A virus. A conformational analysis of the preferred conformations by CD and molecular mechanics was carried out. Present results suggest that the interaction with liposomes as biomembrane model induces and stabilizes the amphipathic beta-structure of the peptide. To study the contribution of amino acid replacements at the RGD tripeptide as well as the influence of the peptide chain length on peptide conformation, solid-phase peptide synthesis of several peptide analogs was carried out and the peptide conformation was studied using CD spectroscopy. The results show that the RGD sequence is necessary to induce the beta-structure in the presence of liposomes.     

Polynucleotides. XLV Synthesis and properties of poly(2'-azido-2'-deoxyinosinic acid)

Poly (2'-azido-2'-deoxyinosinic acid), [poly (Iz)], was synthesized from 2'-azido-2'-deoxyinosine diphosphate by the action of polynucleotide phosphorylase. Poly (Iz) has UV absorption properties similar to poly (I) and hypochromicity of 11% at 0.15M Na+ and neutrality. In solutions of high Na+ ion concentration, poly (Iz) forms a multi-stranded complex and its Tm at 1.0M Na+ ion concentration was 43 degrees. Upon mixing with poly (C), poly (Iz) forms a 1:1 complex having a Tm lower than that of poly (I)-poly (C) complex in the same conditions. The effect of substitution at the 2'-position of the poly (I) strand was discussed in relation to the interferon-inducing activity.     

Elastase-induced hydrolysis of synthetic solid substrates: poly(ester-urea-urethane) and poly(ether-urea-urethane)

Human neutrophil elastase (HNE) and porcine pancreatic elastase (PPE) were incubated with two radiolabelled model poly(urethane), a poly(ester-urea-urethane) containing [14C]toluene diisocyanate ([14C]TDI), poly(caprolactone)(PCL) and ethylenediamine (ED), and a poly(ether-urea-urethane) containing [14C]TDI, poly(tetramethylene oxide) (PTMO) and ED. Ten-fold more radioactive carbon was released when PPE was incubated with [14C]TDI/PCL/ED than when HNE was used. The PPE-induced radioactive carbon release was significantly reduced by a specific elastase inhibitor. Ten-fold less radioactive carbon was released when [14C]TDI/PTMO/ED was incubated with PPE as compared to [14C]TDI/PCL/ED. Since neutrophils, which contain elastolytic activity, are present during the inflammatory response, the stability of biomaterials used in implanted devices may be affected.     

Conformational analysis of two cyclic analogs of angiotensin: implications for the biologically active conformation

Conformations of two cyclic analogs of angiotensin (Asp1-Arg2-Val3-Tyr4-Val/Ile5-His6-Pro7-Phe8, AT), cyclo[Sar1, Cys3, Mpt5]-AT and cyclo[Sar1, HCys3, Mpt5]-AT, were studied, independently employing two complementary techniques, energy calculations and NMR measurements in DMSO solution. NMR data were indicative of well-defined solution conformations for the cyclic moieties of cyclo[Sar1, Cys3, Mpt5]-AT and cyclo[Sar1, HCys3, Mpt5]-AT, including the phi values for the Cys3/HCys3 and Tyr4 residues, as well as the chi 1 value for the Tyr4 residue. Solution conformations for the exocyclic linear parts of both molecules cannot be described by the NMR data with the same precision. At the same time, independent energy calculations revealed the same conformations of cyclic moieties of cyclo[Sar1, Cys3, Mpt5]-AT and cyclo[Sar1, HCys3, Mpt5]-AT among low-energy conformers for both peptides. Moreover, the same conformations are compatible with the model of AT receptor-bound conformation (Nikiforovich & Marshall, 1993), which assumes the particular spatial arrangement of aromatic moieties of Tyr4, His6, and Phe8 residues and the C-terminal carboxyl. These conformers of cyclo[Sar1, Cys3, Mpt5]-AT and cyclo[Sar1, HCys3, Mpt5]-AT contain "an open turn" in the backbone of the Tyr4-Val5 residues, instead of the earlier proposed beta-like reversal, thus confirming the suggestion that the conformation(s) ensuring binding of AT analogs with specific receptors should not be described in terms of a unique backbone conformer.     

Conformational analysis and hemolytic activity of immunoglobulin G fragment 285-292 and its analogs

Theoretical conformational analysis was carried out for the 285-292 fragment of human immunoglobulin G (His-Asn-Ala-Lys-Thr-Lys-Pro-Arg) and its analogues containing Arg, Glu, Gly, Lys, or Trp residue instead of the His residue in position 1. Spectropolarimetic investigation of these peptides showed the analogues to have different activities in the C1q-mediated erythrocytes hemolysis assay. Comparison of the low-energy structures sets of the compounds tested allowed to suggest a model of the "biological active" conformation for the peptide molecule in the course of the C1q complement component binding.     

Polymorphism and disorder of poly(dA).poly(dT) in fibers

OBJECTIVE: The purpose of this report is to describe the clinical history, treatment, pathology, and imaging in two cases of rare CNS infection caused by free-living amebas. The Naegleria fowleri and Acanthamoeba species cause primary amebic meningoencephalitis and granulomatous amebic encephalitis, respectively. We describe the neuroimaging findings of a case involving a nonspecific cerebral edema pattern in primary amebic meningoencephalitis and a case involving focal enhancing lesions in granulomatous amebic encephalitis. CONCLUSION: Primary amebic meningoencephalitis and granulomatous amebic encephalitis have a grave prognosis and, although rare, should be considered in the differential diagnosis for patients who present with appropriate histories and imaging findings, including nonspecific brain edema on CT in primary amebic meningoencephalitis and focal punctate enhancing lesions in the posterior cranial fossa on T1-weighted MR imaging in granulomatous amebic encephalitis.     

Novel derivatives of cyclodextrins, modified with poly(ethylene oxide) and their complexation properties

Sodium chloride transport across isolated cecum mucosa was investigated in normal rats and rats with adaptive cecum growth induced by dietary polyethylene glycol (PEG). The normal cecum absorbed Cl in excess of Na with a small short-circuit current (ISC). Dietary adaptation led to large equivalent increments of Na and Cl net absorption without adequate ISC change. Inhibitor studies (mucosal amiloride 10(-3) and 10(-4) M; mucosal 4, 4-diisothiocyanatostilbene-2,2-disulfonic acid 5 x 10(-5) M; serosal furosemide 10(-3) M; serosal ouabain 10(-3) M) suggested that normal cecal NaCl absorption involves electroneutral Na/H and Cl/HCO3 exchange at the apical and Na-K-ATPase-mediated exit across the basolateral cell membrane. Dietary adaptation stimulates the loosely coupled antiports and possibly activates a small serosally located NaCl cotransport. Comparative histology showed flattening of all tissue layers and widening of crypts in PEG animals. Crypt widening may facilitate ion access to underutilized transport sites and, at least in part, explain the increased absorption of the enlarged cecum.     

Antigenicity of poly(dA-dT) . poly(dA-dT) photocrosslinked with 8-methoxypsoralen

Hepatitis C virus (HCV) shows substantial nucleotide sequence diversity distributed throughout the viral genome, with many variants showing only 68-79% overall sequence homology. This has led to problems in diagnosis of HCV using commercial immunoassays. Based on clustering of homologous sequences, various genotypes and subtypes of HCV have been described from different geographical regions. In the present study, 11 isolates from India were genotyped using sequence comparison for part of the non-structural (NS5) and structural (core) regions. Parts of the genome covering 451 bp (nt 9-459) of the core gene and a 249 bp fragment (nt 7959-8207) of the NS5 gene were reverse transcribed and amplified using nested polymerase chain reaction (RT-PCR). The amplified fragments were cloned and sequenced. The classification into genotypes was done on the basis of phylogenetic analysis. Four isolates showed sequence homology to type 1b. Two of the isolates were classified as type 3a. One isolate was classified as type 3b and the remaining four isolates were found to be variants of type 3 but did not belong to any designated subtype. On the basis of phylogenetic analysis two of the unclassified isolates were put into a new subtype of 3 named as 3g. In one of these variants, parts of a 5'-noncoding (5' NCR; 204 bp), envelope-E1 (435 bp), and NS3 (502 bp) regions were also amplified, cloned, and sequenced. This study demonstrates the type 3 variants including a new subtype (3g) to be the major cause of HCV infection in India.     

苎麻纤维增强聚乳酸复合材料性能研究

通过密炼?注塑成型工艺制备了不同苎麻纤维含量的聚乳酸基复合材料,研究了纤维含量对复合材料性能的影响规律,并揭示了纤维增强机理。研究表明,苎麻纤维的添加提高了复合材料的耐热性能,尤其是当纤维质量分数为40%时,复合材料的热变形温度提高了10.5%。此外,苎麻纤维均匀地分散在基体中,由于纤维与聚乳酸的界面强度较弱,断面上有大量的纤维拔出和纤维孔洞;差示扫描量热仪测试表明高含量的纤维限制了聚乳酸分子链的运动,促进复合材料形成更加致密完善的晶核;同时,流变行为也表明苎麻纤维含量的增加有助于提高复合材料的黏弹响应和复合黏度;最后,苎麻纤维的加入提高了复合材料的拉伸和弯曲强度,且随纤维含量的增加而增大。与聚乳酸相比,当纤维质量分数为40%时复合材料的拉伸和弯曲强度分别提高了30%和21.9%。      

Resistance-modifying agents. 5. Synthesis and biological properties of quinazolinone inhibitors of the DNA repair enzyme poly(ADP-ribose) polymerase (PARP)

Clinical studies concerning the role of poly(ADP-ribose) polymerase (PARP) in the repair of drug- and radiation-induced DNA damage have been impeded by the poor solubility, lack of potency, and limited specificity of currently available inhibitors. A series of 2-alkyl- and 2-aryl-substituted 8-hydroxy-, 8-methoxy-, and 8-methylquinazolin-4(3H)-ones has been synthesized and evaluated for PARP inhibitory activity in permeabilized L1210 murine leukemia cells. 8-Methoxy- and 8-methylquinazolinones (14-34) were readily prepared by acylation of 3-substituted anthranilamides with the appropriate acid chloride, followed by base-catalyzed cyclization. The requisite 8-hydroxyquinazolinones (6, 35-39) were synthesized by demethylation of the corresponding 8-methoxyquinazolinones with BBr3. N-Methylation of 8-methoxy-2-methylquinazolinone (15) with MeI, followed by O-demethylation by BBr3, afforded the control N3-methylquinazolinones 42 and 43, respectively. In general, an 8-hydroxy or 8-methyl substituent enhanced inhibitory activity in comparison with an 8-methoxy group. 2-Phenylquinazolinones were marginally less potent than the corresponding 2-methylquinazolinones, but the introduction of an electron-withdrawing or electron-donating 4'-substituent on the 2-aryl ring invariably increased potency. This was particularly evident in the 8-methylquinazolinone series (IC50 values 0.13-0.27 microM), which are among the most potent PARP inhibitors reported to date. N3-Methylquinazolinones 42 and 43 were essentially devoid of activity (IC50 values > 100 microM). In studies with L1210 cells in vitro, a concentration of 200 microM 8-hydroxy-2-methylquinazolinone (6, NU1025) (IC50 value 0.40 microM) potentiated the cytotoxicity of the monomethylating agent 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide and gamma-radiation 3.5- and 1.4-fold, respectively, at the 10% survival level.     

Conformational properties of a cycle oligosaccharide: cyclotrikis-(1-->6)-[alphaD-glucopyranosyl-(1-->4)-beta-D-glucopyranosy l]

Within a larger environmental health screening program neurobehavioral measures were taken in 384 6-year-old children (mean age 74 months) in the cities of Leipzig, Gardelegen, and Duisburg. Lead concentrations in venous blood samples (PbB) and urinary mercury excretion in 24-h samples (HgU) were measured as markers of environmental exposure by electrothermal AAS. Dependent variables included two subtests from the WISC [vocabulary (V) and block design (BD)] as well as five tests from the NES2 [pattern comparison, pattern memory, tapping, simple reaction time, and the continuous performance test (CPT; child version)]. In addition, visual functions [visual acuity (TITMUS-test) and contrast sensitivity (FACT)] were tested as covariates. The overall average PbB (geometric mean) was 42.5 microg/l (upper 95% value = 89 microg/l). The overall average mercury excretion (HgU) was 0.16 microg/24 h. Whereas no significant or borderline associations between HgU and any of the target variables was found, significant negative associations were observed between PbB and verbal intelligence (WISC vocabulary but not WISC Block Design) and false-positive responses (false alarms), as well as false-negative responses (miss) in the CPT. Whereas parental education was the most important confounder for WISC performance, visual contrast sensitivity and computer familiarity also proved predictive for performance in several computer-based NES subtests. It is concluded that non-IQ measures, namely measures of sustained attention, are negatively affected in children with 95% of blood-lead levels below 90 microg/l, even after adjustment for intelligence and contrast sensitivity, whereas the causative role of lead in altering IQ functions remains somewhat equivocal, because important covariates could not be controlled for.