Synthesis and permeation behavior of membranes from segmented multiblock copolymers containing poly(ethylene oxide) and poly(β-benzyl L-aspartate) blocks

Novel segmented multiblock copolymers ( 7 ) were synthesized by linking poly(ethylene oxide) (PEO) blocks with poly(β-benzyl L -aspartate)(PBLA) blocks via urethane and urea bonds, which were formed by the reaction of 4,4′-methylenediphenyl isocyanate ( 5 ) with the terminal hydroxyl groups of α-hydro-ω-hydroxypoly(oxyethylene) ( 4 ) and the terminal amino groups of poly(β-benzyl L -aspartate)-block-iminohexamethyleneimino-block-poly(β-benzyl L -aspartate) ( 3 ) [prepared from 1,6-hexanediamine ( 1 ) and β-benzyl L -aspartate N-carboxy anhydride ( 2 )], respectively. Membranes with various water contents were obtained from these copolymers by changing the lengths of the PEO and PBLA segments. The study of the permeation of 1-phenyl-1,2-ethanediol, vitamin B₁₂ and myoglobin through the membranes showed a high dependency of the permeability on the molecular weight of the solutes.     

Microtia as an autosomal dominant mutation in a transgenic mouse line: a possible animal model of branchial arch anomalies

Microtia was found in a transgenic mouse 643 and all offspring with microtia had the transgene. No anomalies, other than occasional low set ear and abnormal biting, were identified in other tissues and organs. In the developmental analysis, on the 9th and 10th days of gestation, hypoplasia of the second branchial arch was observed, while various kinds of malformed hillocks were noted on the 12th day. All of these anomalous embryos were transgenic. Histologically, hemorrhage and subsequent phagocytosis were noted at the second branchial arch. Left sided anomalies were predominant and in bilaterally defective ones asymmetry existed. These findings closely resembled to those in experimental animals with a phenocopy of the first and second branchial arch syndrome in humans. Since all other transgenic mouse lines with the same transgene as 643 appeared normal, this dysmorphic phenotype may be caused by an insertional mutation of a host gene, although inappropriate expression of the transgene should be examined further as a possible cause. These results suggest that this transgenic mouse line 643 may be useful as an animal model of branchial arch anomalies in humans.     

Copolymerization of N-carboxy-α-amino acid anhydrides by organometallic compounds

During thermal degradation of poly(vinyl chloride) in a nitrogen atmosphere polyene sequences of different lengths are formed by dehydrochlorination. The distribution of the sequence lengths in the polymer is approximated by analysis of the electron spectra, and the spectroscopically determined polyene content is compared with the amount of hydrogen chloride split off. With increasing temperature, as well as with increasing time of degradation, the distribution of the polyene sequence lengths shifts towards shorter sequences. In contrast to degraded poly(vinyl chloride) powder, degraded poly(vinyl chloride) foils exhibit a marked shift towards longer sequences. Vinylisobutyl ether as comonomer unit in the polymer chains effects a considerable shift of the sequence lengths distribution towards shorter polyene sequences. The spectroscopically determined polyene content agrees with the amount of liberated hydrogen chloride only a t very low conversions while with increasing dehydrochlorination a growing polyene deficit is found. Therefore, it is to be concluded that polyene sequences are consumed by consecutive reactions in which primarily the longer polyene sequences are involved. A further conclusion that may be drawn from these experiments is that the formation of long polyene sequences takes place very rapidly once the initial step of dehydrochlorination has occurred at a labile site. Apart from the above mentioned consecutive reactions, only the number, not the average length, of the polyene sequences changes substantially with increasing time of degradation.     

Components of root bark of morus lhou1 1. Structures of two new natural diels-alder adducts, kuwanons N and o

Kuwanons N and O, two new flavonoid derivatives with a fused dihydrochalcone partial moiety, and four known flavonoid derivatives, morusin, kuwanons G, H, and K, were isolated from the ethyl acetate extract of the root bark of MORUS LHOU (SER.) Koidz. The structures of kuwanons N and O were shown to be 1 and 2, respectively, on the basis of spectral data. They are regarded biogenetically as Diels-Alder adducts of a chalcone and a dehydroprenyl flavonoid.     

A Pilon Fracture With Fibular Head Dislocation Treated With the Use of 3D Preoperative Planning: A Case Report and Literature Review

Pilon fractures with intact fibula have been associated with low-energy trauma. However, the compression force onto the ankle joint can damage the tibiofibular linkage as in a Maisonneuve fracture. Herein, we describe a case of a patient who had a pilon fracture (AO type 43 C3.2) without a fibular fracture. Three-dimensional preoperative simulation by reduction with the surface registration technique was performed as the fibular length was intact and there was no reference for the tibial length. The preoperative simulation revealed superior fibular head dislocation and shortening of the distal tibia. After emergency external fixation on the day of arrival, a 2-staged surgery was performed. During the first operation, the fibular head was reduced and the tibial posterolateral fragment was fixed to restore the tibia length. During the second operation, medial and anterolateral fragments were fixed in order to reduce joint surface of the distal tibia. In general, proximal fibular head fractures are easily overlooked. In the case of pilon fractures with severe length shortening of the tibia without a fibular fracture, a proximal tibiofibular injury should be suspected.     

Structures of four new isoprenylated xanthones, cudraxanthones h,i,j, and k1,2

Four new isoprenylated xanthones, cudraxanthone H,I,J, and K were isolated from the ethanol extract of the root bark of CUDRANIA TRICUSPIDATA (Carr.) Bur. (Moraceae), collected in China. The structures of cudraxanthones H,I,J, and K were shown to be 1- 4, respectively, on the basis of chemical and spectral evidence.     

Structures of three new isoprenylated xanthones, cudraxanthones e, f, and g 1,2

Three new isoprenylated xanthones, cudraxanthones E, F, and G along with a known xanthone, 6-deoxyisojacareubin, were isolated from the ethanol extract of the root bark of CUDRANIA TRICUSPIDATA (Moraceae), collected in China. The structures of cudraxanthones E, F, and G were shown to be 1-3, respectively, on the basis of spectral evidence.