Postmortem distribution of zipeprol

The abuse of zipeprol, an antitussive agent, is prevalent among young people in Korea. For its hallucinogenic effects, abusers have taken overdoses of the drug; thus, fatalities from zipeprol overdose have risen since 1991. In order to determine the postmortem distribution of zipeprol, tissues and blood from 23 decedents who had histories of drug abuse were examined. Homogenized tissue (1 g) and 1 mL blood were extracted by ethyl acetate. Cinnarizine was used as an internal standard. A Varian GC 4600 equipped with a thermionic specific detector was used to quantitate the drug using a DB-5 megabore column, and a Finnigan GC-MS model 4021 was used to obtain mass spectral identification of the extracts. The blood zipeprol concentrations varied from 2.3 to 38.3 micrograms/mL. The highest concentration of zipeprol was found in stomach tissue. Zipeprol concentrations in tissues were higher than the corresponding blood concentrations.

Ubiquitin metabolism in cycling Xenopus egg extracts

Xenopus egg extract is capable of supporting mitosis in vitro, which makes it ideal for biochemical analysis of the cell cycle. Since several studies have implicated the ubiquitin system in cell cycle progression, we have measured ubiquitin conjugation rates, proteolysis of ubiquitin-lysozyme conjugates, and rates of isopeptidase activity in cycling Xenopus egg extracts. Although ubiquitin conjugation in cytostatic factor arrested extract was half that in activated extract, there were no changes in rates of ubiquitin conjugation during the cell cycle. Ubiquitin conjugates are degraded by a 26 S ATP-stimulated protease. The ability of the 26 S protease to degrade ubiquitin-lysozyme conjugates and a fluorigenic peptide also remained constant across the cell cycle. In contrast to previously characterized systems, isopeptidase activity in Xenopus egg extract is energy-dependent. Glycerol gradient fractionation of Xenopus egg extract separated two ATP-dependent isopeptidases. On co-sedimented with the 26 S protease; the other sedimented slower and was not associated with any additional proteolytic activity. As found for rates of Ub conjugation and conjugate proteolysis, there was little or no variation in isopeptidase activity during the cell cycle.

Ubiquitin-RAS peptide extensions as substrates for farnesyl-protein transferase and carboxymethyltransferase

Using oligonucleotide-mediated 'loop-in' mutagenesis strategies in M13, a heat-inducible ubiquitin (Ub) gene was extended by sequences coding for the C-terminal 11 amino acids of Ha-RAS. The resulting gene was transformed into AR13 and production of the Ub-peptide extension was induced by heat treatment. After one-step purification, the fusion protein (Ub-cRAS) was used as a substrate for farnesyl-protein transferase. Ub-cRAS was farnesylated on incubation in Xenopus egg extract or rabbit reticulocyte lysate. In contrast, when serine was substituted for the last cysteine in the RAS extension, transfer of the [3H]farnesyl group from [3H] farnesyl pyrophosphate to the modified Ub-cRAS was not observed. Farnesylation of Ub-cRAS permitted us to develop an easy membrane-binding assay for farnesyl-protein transferase enzyme activity. Using this assay, we partially purified the enzyme from rabbit reticulocyte lysate. We also detected methylation of the farnesylated Ub-cRAS terminus in Xenopus egg extract.

The use of ubiquitin-peptide extensions as protein kinase substrates

Four ubiquitin-peptide extensions prepared as cloned products in E. coli were tested as casein kinase II substrates. Two extensions containing the sequence Ser-Glu-Glu-Glu-Glu-Glu were readily phosphorylated by partially purified rabbit reticulocyte casein kinase II. The other two fusion proteins, which lack a consensus phosphorylation site for casein kinase II, did not serve as substrates under identical reaction conditions. Native ubiquitin was not phosphorylated by reticulocyte casein kinase II, nor have we observed its phosphorylation in crude extracts from HeLa cells, mouse liver, or Xenopus eggs. Ubiquitin's apparent lack of phosphorylatable residues coupled with its remarkable heat stability and rapid migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels make the protein an attractive carrier for carboxyl-terminal peptides containing specific phosphorylation sites. Such ubiquitin extension proteins should prove valuable as protein kinase substrates.

Synthesis of peptides as cloned ubiquitin extensions

Oligonucleotides encoding four peptides ranging in length from 10 to 21 amino acids were cloned between the Afl2 and KpnI sites in the ubiquitin expression vector, pNMHUb. Escherichia coli AR13, a strain that contains a temperature-sensitive lambda repressor, was transformed by the plasmids, and upon shift to 42 degrees C, the cells produced large amounts of ubiquitin extended at its carboxyl terminus by each of the four peptides. Following a simple three-step purification of the ubiquitin fusion proteins, the peptides were cleaved from ubiquitin using a ubiquitin-alpha-protein hydrolase isolated from rabbit reticulocytes. The released ubiquitin molecules were shown to be competent in conjugation assays, and amino acid analyses of the purified peptides revealed that full length products were obtained in all cases. Since peptide yields varied from 2 to 4 mg/liter of culture medium, ubiquitin extensions provide an attractive alternative to solid phase synthesis for the production of peptides.

Present status of fast neutron therapy in Asian countries

The present status of the treatment with fast neutrons performed in Asian countries is reviewed and the experiences with respect to the radiobiological indications are presentated and discussed. There are three facilities under operation, the National Institute of Radiological Sciences (NIRS) in Chiba, the Institute of Medical Science (IMS) in Tokyo and the Korea Cancer Center Hospital (KCCH) in Seoul. The clinical experiences can be summarized as follows: Fast neutrons are the treatment of choice for carcinoma of the salivary gland, Pancoast tumor of the lung, osteosarcoma, soft tissue sarcoma and malignant melanoma. Provided the isodose planning can be improved, it seems that also squamous cell carcinoma of the head and neck and esophagus, adenocarcinoma of the lung, stage I and prostatic adenocarcinoma can be benefit from neutron therapy. The same holds for malignant meningioma, while the benefit for glioblastoma multiforme has not yet been confirmed. Studies are going on for the treatment of other cancers and for evaluating the possible role of neutron therapy in combination with surgery.

Prophylactic oral nystatin and fungal infections in very-low-birthweight infants

Prevention of systemic fungal infection in the very-low-birthweight infant is important since it is associated with a high morbidity and mortality. To determine if oral nystatin administration could prevent fungal colonization and infection, we evaluated 67 preterm infants with birthweights less than 1250 gm. Thirty-three infants received 1 ml (100,000 units/ml) of nystatin inside the mouth every 8 hours until 1 week after extubation. Oropharyngeal, rectal, blood, and urine cultures were obtained on the 1st day of life and weekly. Endotracheal cultures were obtained three times a week from intubated infants. Four (12%) of the 33 nystatin-treated infants had positive cultures, two (6%) developed systemic infection. The control group consisted of 34 infants, 15 (44%) had positive fungal cultures and 11 (32%) developed systemic infection. Fungi isolated were Candida species and Torulopsis glabrata. Colonized infants were dependent on the respirator (P less than 0.001), had indwelling catheters (P less than 0.01), and received antibiotics (P less than 0.05) for a longer period than infants free from fungi and their mortality was significantly higher (P less than 0.05). We conclude that prophylactic administration of oral nystatin reduces fungal colonization and infection in very-low-birthweight infants.