Epigastric appendiceal abscess with spontaneous drainage into the stomach

The appendiceal abscess is a common complication of acute appendicitis and usually is located in the right lower quadrant of the abdomen. An epigastric appendiceal abscess has never been reported at an unusual location. We experienced an unusual case of a 49-year-old man with an epigastric appendiceal abscess. Initially, this abscess was suspected to be a pancreatic abscess. Abdominal CT scan and barium enema demonstrated a hyperrotated cecum with an appendiceal abscess in the left upper quadrant of the abdomen. An gastroscopy revealed a small fistula-like lesion with purulent coating at the bulging posterior gastric wall. The abscess resolved spontaneously. We believe that the abscess drained into the stomach through a small fistula between the stomach and abscess cavity. There was no recurrence for over 6 months.

The comparative molecular study between Bombycidae and Saturniidae based on mtDNA RFLP and cytochrome oxidase I gene sequences: implication for molecular evolution

The phylogenetic relationships between Bombyx mori and Bombyx mandarina species of Bombycidae, and Antheraea yamamai and Antheraea pernyi species of Saturniidae were investigated based on mtDNA RFLP and cytochrome oxidase I gene. The sizes of the mtDNA of all the species were estimated at approximately 16 kbp +/- 500 bp by total length of all the restricted fragments and no variation in size was recognized. Of the fourteen different restriction endonucleases used, BamHI, HindIII, PstI, EcoRI and XbaI showed RFLP. Among these, only HindIII showed RFLP between B. mori and B. mandarina. A comparative analysis of sequences was also conducted with the mitochondrial cytochrome oxidase I genes of each species. The results indicated that B. mori shared a 97%, 85% and 87% sequence identity with B. mandarina, A. yamamai and A. pernyi, respectively. B. mandarina shared a 87% and 88% sequence identity with A. yamamai and A. pernyi, respectively. A. yamamai shared 92% sequence identity with A. pernyi. The results of the phylogenetic analysis exhibited monophyly and confidence limits of more than 99% in all trees for both Bombycidae and Saturniidae.

Change in centromeric and acentromeric micronucleus frequencies in human populations after chronic radiation exposure

Acute radiation exposure of humans was observed to induce various forms of cytogenetic damage, including increased frequencies of micronuclei and chromosomal aberrations. However, the cytogenetic effects of chronic low dose radiation exposure in vivo needs further characterization. Sixteen subjects with chronic low dose rates of gamma-radiation exposure from 60Co-contaminated steel in radioactive buildings were compared with seven non-exposed reference subjects for micronucleus frequencies after they relocated. By in situ hybridization using a digoxigenin-labeled anti-alpha all human centromere probe, the exposed subjects were shown to have a significant increase in cytochalasin B-modulated micronucleus (CBMN) frequencies, as well as a significant increase in centromere-positive (C+) CBMN, centromere-negative (C-) CBMN, total C+signals, single C+ MN signals and multiple C+ signals/1000 binucleated cells (BN). However, decreases in the ratios C+MN/C- MN and C+MN/total CBMN (%) were also noted in the exposed subjects. By mixed effects analysis, considering individuals from the same families, the C- MN and single C+ MN/1000 BN were both positively and moderately associated with previous cumulative exposure. When the time period of relocation post-exposure (relocation time or RT) was considered, total C+MN and multiple C+MN/1000 BN were negatively and significantly associated with RT. Moreover, the C+MN, C- MN, C+MN/C- MN ratio and single C+MN/1000 BN were all negatively and moderately associated with RT, but not with exposure dose. This suggested that acentromeric and single or multiple centromeric CBMN cytogenetic damage seems to disappear differentially in human subjects post chronic low dose radiation exposure.

Estimation of expected utility gained from the helmet law in Taiwan by quality-adjusted survival time

The objective of this study was to empirically estimate the expected utility gained from the implementation of the 1997 helmet law in Taiwan by using quality-adjusted survival time (QAST). We randomly selected 400 out of 8221 registered cases of head injury and successfully interviewed 99 cases with the index of health-related quality of life (IHRQ). The function of IHRQ was then multiplied with the corresponding survival function to obtain the QAST for head injury. The total utility gained from the helmet law in Taipei within 1 year was estimated by multiplying the expected loss of utility per patient with the number of prevented cases. The results showed that after 80 months of follow-up, the QAST of the injured population was 66.3 quality-adjusted life-months (QALMs), while that of the reference population was 78.7 QALMs. We extrapolated the QAST for total life expectancy by simulating the survival of head injury cases using the life table data from the general population. The life-long utility loss of a head injury case was found to be 4.8 quality-adjusted life-years (QALY). The number of prevented cases during the first year of enforcement of the helmet law was estimated to be 1300 cases in Taipei, which amounted to 6240 QALYs gained. For lack of data, we were unable to calculate the possible gain from helmet on reduction of severity among nonfatal cases with head injury, and the estimation was only a lower bound. We concluded that the QAST approach is a feasible approach applicable to health policy decision-making, especially in cost-utility analysis.

Specific contacts between residues in the DNA-binding domain of the TyrR protein and bases in the operator of the tyrP gene of Escherichia coli

In the presence of tyrosine, the TyrR protein of Escherichia coli represses the expression of the tyrP gene by binding to the double TyrR boxes which overlap the promoter. Previously, we have carried out methylation, uracil, and ethylation interference experiments and have identified both guanine and thymine bases and phosphates within the TyrR box sequences that are contacted by the TyrR protein (J. S. Hwang, J. Yang, and A. J. Pittard, J. Bacteriol. 179:1051-1058, 1997). In this study, we have used missing contact probing to test the involvement of all of the bases within the tyrP operator in the binding of TyrR. Our results indicate that nearly all the bases within the palindromic arms of the strong and weak boxes are important for the binding of the TyrR protein. Two alanine-substituted mutant TyrR proteins, HA494 and TA495, were purified, and their binding affinities for the tyrP operator were measured by a gel shift assay. HA494 was shown to be completely defective in binding to the tyrP operator in vitro, while, in comparison with wild-Type TyrR, TA495 had only a small reduction in DNA binding. Missing contact probing was performed by using the purified TA495 protein, and the results suggest that T495 makes specific contacts with adenine and thymine bases at the +/-5 positions in the TyrR boxes.

Clinical courses and changes of pancreatic beta-cell function in young-onset diabetics: report of two cases

Accurate classification of diabetes in some young patients is difficult but clearly of importance in deciding the appropriate treatment. We report the different clinical courses and beta-cell function changes in 2 young-onset diabetics. In the beginning, each of them was considered to be a patient with insulin-dependent diabetes mellitus (IDDM) and was treated with insulin. Then, treatment was shifted from insulin to oral hypoglycemic agents (OHA) because each patient's beta-cell function was comparable to that of patients with non-insulin-dependent diabetes mellitus (NIDDM). In case 1, the patient's glycemic control and beta-cell function progressively deteriorated and finally insulin therapy was required. In case 2, the patient was continuously treated with OHA. Although his blood glucose was not well-controlled, his beta-cell function had been well-preserved. Recently he achieved near-normoglycemia by improving his diet and OHA compliance. Clearly, case 1 was a slowly progressive Type 1 DM patient and case 2 was a young Type 2 DM patient. This classification was further supported by the finding that the patient in case 1 had human leukocyte antigen (HLA)-DR3, but the patient in case 2 did not.

Synthesis of sulfonylurea conjugated copolymer via PEO spacer and its in vitro short-term bioactivity in insulin secretion from islets of Langerhans

In order to reduce the number of immunoprotected islets required in xeno- or allogenic transplants for reversing diabetes, analogues of glyburide (a sulfonylurea), an extremely hydrophobic insulin secretagogue, were synthesized and used in an attempt to produce water soluble sulfonylurea (SU) grafted polymers. After synthesizing various polymers containing glyburide analogues, a poly(N-vinyl-2-pyrrolidone-co-sulfonylurea succinyl PEO (Mw = 3000) acrylate) was found to be soluble in a cell culture medium at pH 7.4. However, solubility was only obtained by decreasing solution pH from 11 to 7.4. When the copolymer was added to the islet cell culture media at a concentration of 5 microg ml(-1) (based on the theoretical SU content of the copolymer), insulin secretion was enhanced by about 30% at low glucose concentrations of 50 and 100 mg dl(-1) compared to the control. This is equivalent to 40-60% bioactivity of glyburide. The polymer's effect on insulin secretion at a higher glucose concentration of 200 mg dl(-1) was not significant. Considering the previous results where a similar but insoluble polymer without a PEO spacer was used and the polymer showed SU bioactivity only at a glucose concentration of 50 mg dl(-1), the observations from this study indicates that the solubility of SU-grafted polymers may affect the binding of SU groups to SU receptors on the pancreatic beta-cells, resulting in improved pharmacodynamic effect of SU.

Adverse effect of air pollution on respiratory health of primary school children in Taiwan

This study is a part of the Study On Air Pollution and Health In Taiwan (SOAP&HIT), an ongoing research project involving cooperation of several universities in Taiwan. In this study, the objective was to evaluate the effects of ambient air pollution on respiratory symptoms and diseases of school children, in addition to considering indoor air pollution. Six communities were selected: one community located in a rural area (Taihsi), two in urban areas (Keelung and Sanchung), and the other three in petrochemical industrial areas (Toufen, Jenwu, and Linyuan). We sampled 5,072 primary school students in six communities from the main study population of SOAP&HIT. Respiratory health was assessed by evaluation of the children's respiratory symptoms and diseases using a parent-completed questionnaire. Data were analyzed using logistic regression analysis to compute odds ratios of adverse effect. The school children in the urban communities had significantly more respiratory symptoms (day or night cough, chronic cough, shortness of breath, and nasal symptoms) and diseases (sinusitis, wheezing or asthma, allergic rhinitis, and bronchitis) when compared with those living in the rural community. However, only nasal symptoms of children living in the petrochemical communities were more prevalent than in those living in the rural community. Although the association with ambient air pollution is suggestive, the cross-sectional study cannot confirm a causal relationship; thus further studies are needed.

Magnetically aligned phospholipid bilayers with positive ordering: a new model membrane system

A stable smectic phospholipid bilayer phase aligned with the director parallel to the magnetic field can be generated by the addition of certain trivalent paramagnetic lanthanide ions to a bicellar solution of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC) in water. Suitable lanthanide ions are those with positive anisotropy of their magnetic susceptibility, namely Eu3+, Er3+, Tm3+, and Yb3+. For samples doped with Tm3+, this phase extends over a wide range of Tm3+ concentrations (6-40 mM) and temperatures (35-90 degrees C) and appears to undergo a transition from a fluid nematic discotic to a fluid, but highly ordered, smectic phase at a temperature that depends on the thulium concentration. As a membrane mimetic, these new, positively ordered phospholipid phases have high potential for structural studies using a variety of techniques such as magnetic resonance (EMR and NMR), small-angle x-ray and neutron diffraction, as well as optical and infrared spectroscopy.

Respiratory symptoms of primary school children living in a petrochemical polluted area in Taiwan

In 1994-1995 a cross-sectional epidemiological study investigating the respiratory health of school children in two Taiwan areas was conducted; one area was located in a region with petrochemical manufacturing complexes (Linyuan), and the other was situated in a reference area with no local industrial emissions (Taihsi). All primary school children residing in the two areas were involved in the study. Four hundred seventy children were studied in the area with high exposure to industrial emissions, and 611 children lived in the reference area. Respiratory health was assessed by evaluation of the children's respiratory symptoms and illnesses, using a parent-completed questionnaire. Particulates, sulfur dioxide (SO2), nitrogen dioxide (NO2), and acid aerosols levels were significantly higher in the exposed area than in the reference area. The school children in the petrochemical area had significantly more upper respiratory symptoms and asthma compared with the children living in the control area. Although the association with known petrochemical air pollution is suggestive, this cross-sectional study cannot confirm a causal relation and further studies are needed.

Radiation exposure modeling for apartment living spaces with multiple radioactive sources

Since late 1992, over 100 building complexes in Taiwan, including both public and private schools, and 1,000 apartments have been identified as emitting elevated levels of gamma-radiation. These high levels of gamma-radiation have been traced to construction steel contaminated with 60Co. Accurate reconstruction of the radiation exposure dosage among residents is complicated by the discovery of multiple radioactive sources within the living spaces and by the lack of comprehensive information about resident life-style and occupancy patterns within these contaminated spaces. The objective of this study was to evaluate the sensitivity of current dose reconstruction approach employed in an epidemiological study for the health effects of these occupants. We apply a statistical method of local smoothing in dose rate estimation and examine factors that are closely associated with radiation exposure from multiple radioactive sources in the apartment. Two examples are used, a simulated measurement in a hypothetical room with three radioactive sources and a real apartment in Ming-Shan Villa, one of the contaminated buildings. The simulated and estimated means are compared along 5-10 selected points of measurement: by local smoothing approach, with the furniture-adjusted space, and with the occupancy time-weighted mean. We found that the local smoothing approach came much closer to theoretical values. The local smoothing approach may serve as a refined method of radiation dose distribution modeling in exposure estimation. Before environmental exposure assessment, "highly occupied zones" (HOZs) in the contaminated spaces must be identified. Estimates of the time spent in these HOZs are essential to obtain accurate dosage values. These results will facilitate a more accurate dose reconstruction in the assessment of residential exposure in apartments with elevated levels of radioactivity.

Critical base pairs and amino acid residues for protein-DNA interaction between the TyrR protein and tyrP operator of Escherichia coli

In Escherichia coli K-12, the repression of tyrP requires the binding of the TyrR protein to the operator in the presence of coeffectors, tyrosine and ATP. This operator contains two 22-bp palindromic sequences which are termed TyrR boxes. Methylation, uracil, and ethylation interference experiments were used to identify the important sites in the TyrR boxes that make contacts with the TyrR protein. Methylation interference studies demonstrated that guanines at positions +8, -5, and -8 of the strong TyrR box and positions +8, -4, and -8 of the weak box are close to the TyrR protein. Uracil interference revealed that strong van der Waals contacts are made by the thymines at position -7 and +5 of the top strands of both strong and weak boxes and that weaker contacts are made by the thymines at positions +7 (strong box) and -5 and +7 (weak box) of the bottom strand. In addition, ethylation interference suggested that the phosphate backbone contacts are located at the end and central regions of the palindrome. These findings are supported by our results derived from studies of symmetrical mutations of the tyrP strong box. Overall, the results confirm the critical importance of the invariant (G x C)(C x G)8 base pairs for TyrR recognition and also indicate that interactions with (T x A)(A x T)7 are of major importance. In contrast, mutations in other positions result in weaker effects on the binding affinity of TyrR protein, indicating that these positions play a lesser role in TyrR protein recognition. Alanine scanning of both helices of the putative helix-turn-helix DNA-binding motif of TyrR protein has identified those amino acids whose side chains play an essential role in protein structure and DNA binding.

The efficacy of endoscopic sphincterotomy in patients with sphincter of Oddi dysfunction

BACKGROUND

Dysfunction of the sphincter of Oddi (SOD) is one of the causes of postcholecystectomy syndrome and biliary pain. Endoscopic sphincterotomy (EST) is recommended in some patients refractory to conservative treatment. This study was designed to evaluate the efficacy of, and complications from EST in patients with SOD.

METHODS

Between 1990 and 1993, 24 patients clinically diagnosed as having papillary stenosis were treated by endoscopic sphincterotomy. All patients had dilated common bile duct (CBD) in addition to 1) elevation of transaminases and alkaline phosphatase (n = 13); 2) elevation of transaminases and serum amylase (n = 4); 3) normal liver enzymes but delayed biliary emptying on quantitative hepatobiliary scintigraphy (QHS) (n = 7). No CBD stones, organic obstruction or other disorders were found in these patients.

RESULTS

EST was successfully performed in 24 patients. One patient had minor hemorrhage and one patient developed pancreatitis after EST. Twenty-two of the 24 patients (91.7%) were symptomatically improved before discharge. Twenty-one patients were regularly followed over a median period of 18 months (range 5-36) after EST. Two patients with symptom had recurrence at five and eight month follow up because of restenosis of papilla; another two patients with recurrent biliary symptoms, but the sphincter of Oddi remained wide open. Seventeen of 21 regularly followed patients were symptom free after the median 18-month follow up.

CONCLUSIONS

EST is an effective and safe modality for treatment of sphincter of Oddi dysfunction.

Bioflocculant produced by Aspergillus sp. JS-42

A bioflocculant from a fungus, Aspergillus sp. JS-42, was purified by precipitations with acetone and cetylpyridinium chloride. The flocculating activity was not significantly affected by pH from 3 to 8, but was stimulated by the addition of CaCl2, and was effective only when the reaction mixture contained an adequate amount of flocculant. The flocculant could efficiently flocculate all tested solids suspended in aqueous solution, including various microorganisms, organic acids, and inorganic materials.

Estimation of expected quality adjusted survival by cross-sectional survey

To compare both mortality and quality of life (QOL) across different illnesses, we propose an estimator to calculate the expected quality adjusted survival (QAS) by multiplying the QOL into the survival function. While the survival function can be determined by the usual life table method, the QOL data can be collected by a cross-sectional survey among patients who are currently surviving. The area under the QAS curve is thus the expected utility of health of the specific illness, which may take a common unit of quality adjusted life year ready for outcome evaluation and policy decision. A simulation is performed to demonstrate that the proposed estimator and its standard error are relatively accurate. The limitations and guidelines for using this estimator are also discussed.

Estimation of the shelf-life of drugs with mixed effects models

This paper proposes a normal mixed effects model for stability analysis. An EM algorithm is developed to compute the maximum likelihood estimates of regression coefficients of the fixed effects and random effects, and variance components. The likelihood ratio test is used for the preliminary testing of batch-to-batch variation. An example from a marketing stability study is given to illustrate the proposed procedure.

Ecology and control of dengue vector mosquitoes in Taiwan

Due to rapid urbanization, industrialization and social changes in recent years, the use of packing materials and tires has dramatically increased in the Taiwan area. What is more is that some parts of southern Taiwan are short of water resources and water preservation with huge containers becomes part of custom in those areas. Storage water containers, waste vessels and tires are good habitats for Aedes. Meanwhile, some persons traveling to dengue endemic countries bring the dengue disease back to Taiwan. Surveys taken since 1988 show that dengue occurs mainly in the urban and coastal areas where Aedes aegypti is prevalent. This species is the most important, if not the only, vector of dengue in Taiwan. It appears that the types of Aedes breeding have changed quickly. In dengue fever epidemic areas, the most popular breeding sites are ornamental containers (38.8%), storage water containers (30.1%), discarded containers (25.4%), receptacles (3.3%) and water collection in the basement (2.2%). In dengue fever epidemic areas, those building basements, huge water containers, waste vessels and waste tires in open fields are most difficult to clean up and manage and become the most popular Aedes habitats. We established a waste recycling system and promoted a breeding site reduction campaign for waste management, including the application of Temephos in containers to kill larvae. For the drinking water management, fish were released in water containers to prevent larval breeding. It should be mentioned that with the integrated pest control and regular inspections of Aedes larvae in Taiwan the density figures 1, 2-5, and 6 or above for Aedes aegypti were 38.7%, 42.9%, and 18.4%, respectively, in 1988, and in 1993 were 90.8%, 9.2% and 0%. The incidence of dengue fever cases has 98% decreased since 1988. In 1990 and 1993, there was no indigenous cases. We have concluded that integrated pest control is the best and most effective method for dengue fever control, including solid waste and drinking water management.

Recovery and disposal of discarded tires in the Taiwan area

Urbanization and industrialization has resulted in a vast amount of artificial water containers in Taiwan, especially discarded automobile tires. 3.5 million automobile tires and several million motorcycle tires are discarded annually. The discarded tires contaminate the environment and also become a substantial number of breeding sites for the dengue vector mosquitoes. In order to establish a sound system for the recovery and disposal of discarded tires and to control dengue fever through source reduction, it has been emphasized that users must pay for their waste. It is necessary to recover and properly dispose of these discarded tired. The commercial firms which sell or manufacture tires are therefore advised to cooperate with the Environmental Protection Administration of the Executive Yuan, R.O.C. and follow the "Regulations of Recovery and Disposal of Discarded Tires". They are requested to establish foundations for the recovery of discarded tires. Those who are willing to join should prepay a deposit or related charge by the size of tire, which is imported or locally manufactured. The foundation utilizes the deposits for the recovery and disposal of discarded tires. From 1991 to 1993 the commercial tire firms had already achieved the 80% recovery rates declared by the authorities concerned. Some of the tires, after having been recovered, were recycled in the original form and the rest were cut into small pieces for recycling after physical treatment. It should be mentioned that the Department of Environmental Protection of Kaohsiung City has collected 80 thousand discarded automobile tires to be used as ocean jetty.(ABSTRACT TRUNCATED AT 250 WORDS)

Operative choledochoscopy in patients with acute cholangitis: a prospective, randomized study

A prospective, randomized evaluation of operative choledochoscopy was carried out during emergency surgery in patients with acute cholangitis or acute suppurative cholangitis when conservative management had failed. After common bile duct exploration, 79 patients were randomized to have choledochoscopy and 78 patients to the control group. Laboratory and clinical parameters showed that choledochoscopy did not increase the incidence of septicaemia, acute pancreatitis, persistent cholangitis, postoperative wound sepsis, intraperitoneal sepsis and hospital mortality. The incidence of retained common bile duct stones detected by T tube cholangiography performed in the second postoperative week was significantly reduced (P less than 0.01) after choledochoscopy. Choledochoscopy detected stones missed by conventional common bile duct exploration in ten patients. It is concluded that choledochoscopy is a safe and effective technique in patients with acute cholangitis and acute suppurative cholangitis.

[A review of larvivorous fish]

Recently, because of concern about the effects of insecticide on the environment, increased attention is being given to the use of biological agents for controlling the vectors of human disease. Biological control may encompass the use of predators, pathogens, parasites, pheromones, insect growth regulators, and other factors. Of these agents only fish and bacteria have so far been used operationally in mosquito control. Since 1988 fish have been employed for controlling Aedes larvae in water containers in Liuchiu, Pingtung. A review of larvivorous fish (mainly Gambusia affinis) and the present status of the use of fish in mosquito control in Mainland China are thus made for ready reference for the workers in mosquito control in Taiwan.

[Preliminary study on the biological control of dengue vectors by fish in Liouchyou Prefecture, Pingtung County, Taiwan]

An investigation made in May 1989 with questionnaires to 2,480 families in Liouchyou Prefecture, Pingtung County, showed that there were about 6,533 water containers in the whole village, of which 49.83% were used to store water for drinking, and the remaining 50.17% were used for washing clothes and watering plants. 32.42% of the residents volunteered to rear fish in the family water containers to control the mosquito population. During the period from April to October 1989, there was a total approximately 17,600 Gambusia affinis, Poecilia reticulata, Tilapia mossambica, and Sarotherodon niloticus released into the household water containers in the Liouchyou areas to control dengue vectors--Aedes aegypti and Aedes albopictus. One month after the release, a comparison of the container index of Aedes larvae showed that among 530 containers with fish in them, the positive container index was 3.58; among the 3,219 containers without fish in them, it was 25.97. Furthermore, the positive container index without fish was as high as 97.32 in May 1989, and dropped to as low as 18.00 at the end of September 1989. This indicats that rearing fish to control household mosquitoes yielded significant results in the initial stage. Also, in some water containers Gambusia affinis and Porcilia reticulata lived longer than five months, and Gambusia affinis could eat 31.33 Aedes larvae/0.4078g fish per day on the average. It appears that the biological control of dengue vectors by fish in the Liouchyou areas would be advantageous.

Analogues of chloramphenicol: circular dichroism spectra, inhibition of ribosomal peptidyltransferase, and possible mechanism of action

Circular dichroism spectra of series of chloramphenicol derivatives la-r were measured in water at pH 7. Compounds 1a-o exhibit two positive Cotton effects at 310--340 and 240--260 nm, respectively, and a weaker negative Cotton effect at 280--300 nm. In analogues 1c, 11, and 1m there is only a minimum between the two positive Cotton effects. Derivatives 1p--r possess a strong negative Cotton effect at ca. 280 nm. Compounds 1a--r were examined as inhibitors of the puromycin reaction with Escherichia coli 70S ribosome-poly(U)-N-AcPhe-tRNA complex. Analogues 11, 1n, lo, and lq are potent competitive inhibitors of puromycin comparable to or better than chloramphenicol (1b). Compounds 1k and 1m are less active, whereas 1d--g and 1j are only moderately effective. The rest of the analogues have marginal or no activity. The results are compared with previous biological data and discussed in terms of a retro-inverso relationship of chloramphenicol (1b) to the aminoacyl moiety of puromycin (aminoacyl-tRNA) and to a hypothetical transition state of peptide bond formation.

Chemical aminoacylation of transfer ribonucleic acid. The reaction of Escherichia coli tRNA with ethyl N-benzyloxycarbonylorthoglycinate

The alpha-carbethoxypentadecyltrimethylammonium (Septonex) salt of tRNA (Ib) was condensed with ethyl N-benzyloxycarbonylorthoglycinate (II) in dimethylformamide in vacuo and in the presence of H3PO4 as catalyst. Pancreatic RNAase degradation and phenylalanine acceptor activity showed a 55--60% conversion to the 2',3'-cyclic orthoglycinate derivative of tRNA (IIIb). The orthoester grouping of IIIb was quantitatively hydrolyzed in 80% formic acid at 0 degrees C for 15 min to give 2'(3')-O-(N-benzyloxycarbonyl)glycyl tRNA (IVb). The latter was stripped at pH 8.8 to give tRNA whose behavior on DEAE cellulose column and gel electrophoresis was similar to that of starting tRNA. The phenylalanine acceptor activity amounted to almost 80% of the starting tRNA.