The synthesis of 4′,6′-diacetamido-4′,6′-dideoxycellobiose hexa-acetate from lactose

Reaction of methyl 4′,6′-di-O-mesyl-β-lactoside pentabenzoate (8), synthesised via the 4′,6′-O-benzylidene derivative (6), with sodium azide in hexamethylphosphoric triamide gave three products. In addition to the required 4′,6′-diazidocellobioside (9), an elimination product, methyl 4-O-(6-azido-2,3-di-O-benzoyl-4,6-dideoxy-α-L-threo-hex-4-enopyranosyl)-2,3,6-tri-O-benzoyl-β-D-glucopyranoside (12), and an unexpected product of interglycosidic cleavage, methyl 2,3,6-tri-O-benzoyl-β-D-glucopyranoside (13), were formed. The origin of the latter product is discussed. The diazide 9 was converted into 4′,6′-diacetamido-4′,6′-dideoxycellobiose hexa-acetate (16) by sequential debenzoylation, catalytic reduction, acetylation, and acetolysis.     

ESTABLISHMENT OF A CLONAL STRAIN OF HEPATOMA CELLS WHICH SECRETE ALBUMIN

A clonal strain of epithelial cells (designated MH₁C₁) has been established from the transplantable Morris hepatoma No. 7795. The cells have maintained distinctive morphology throughout more than 20 subcultures (split 1:5) at 2- to 4-week intervals in supplemented Ham's F 10 medium. They contain many highly refractile, round, cytoplasmic bodies which stain bright red with Oil Red O. The population doubling time was 2 wk when the clonal strain was first established. It has gradually decreased to 1 wk. The cells synthesize rat serum albumin and secrete it into the culture medium as determined immunologically by microcomplement fixation and double diffusion. Albumin secretion (3–6 µg albumin/mg cell nitrogen/24 hr) occurs throughout the logarithmic phase of cell proliferation and has not diminished during serial propagation since the strain was initiated 15 months ago.     

Growth of Chlorella sorokiniana at Hyperbaric Oxygen Pressures

The growth rate of Chlorella sorokiniana decreased in a linear fashion as the partial pressure of oxygen was increased from 711 to 1,478 mm of Hg. Under two atmospheres of oxygen pressure, growth ceased after 10 to 12 hr. This cessation of growth was not due to any permanent injury, as growth resumed when oxygen partial pressure was reduced to ambient levels. The inhibition occurred under both autotrophic and heterotrophic growth conditions and was not accompanied by an increase in cell size. The results indicated that the tolerance of Chlorella cells to elevated oxygen pressures was not an absolute immunity, and that inhibition of growth at very high oxygen pressures cannot be accounted for by an inhibition of photosynthesis alone.     

Factors Influencing In Vitro Skin Permeability Factor Production by Vibrio cholerae

The development of a new semisynthetic medium which stimulates in vitro production of the skin permeability factor (PF) by Vibrio cholerae is described. The effects of pH, aeration, temperature, and length of incubation on PF formation or release in strain 569B and several other strains, or both, are compared. Data are presented which show that maximal PF accumulation occurs during a transitional period of growth joining the exponential and stationary phases of the growth cycle. PF elaboration is completed well ahead of any visible signs of lysis in the culture and the PF activity appears to be proportional to the length of the linear growth phase. Possible mechanisms of toxigenicity and the nature of PF are discussed.     

The role of fetal urinary excretion in the transfer of ethanol into amniotic fluid after maternal administration of ethanol to the near-term pregnant ewe

The objective of this study was to determine whether fetal urinary excretion is a major route of ethanol transfer into the amniotic fluid surrounding the fetus following maternal administration of ethanol. Conscious instrumented pregnant ewes between 130 and 137 days' gestation (term, 147 days) with (n = 3) or without (n = 3) a catheter in the fetal bladder were administered 1 g ethanol/kg maternal body weight as a 1-h maternal intravenous infusion. Maternal blood, fetal blood, and amniotic fluid samples were collected at selected times, and fetal urine was collected continuously from the bladder-cannulated fetus during the 14-h study for the determination of ethanol concentrations. Fetal urinary excretion of ethanol occurred, and the total amount of ethanol excreted represented 0.30 +/- 0.07 (SD)% of the maternal ethanol dose. The renal clearance of ethanol by the fetus was 0.43 +/- 0.06 mL/min. The pharmacokinetics of ethanol in the maternal-fetal unit and the amniotic fluid for the bladder-cannulated fetal preparation were similar to the data for the nonbladder-cannulated preparation. The data indicate that fetal urinary excretion of ethanol is a secondary route of ethanol transfer into the amniotic fluid. It would appear that diffusion of ethanol across membranes from the maternal and fetal circulations is a major route of ethanol transfer into this intrauterine compartment.     

Gene 18 protein of bacteriophage T7. Overproduction, purification, and characterization

Genetic and physical analyses indicate that gene 18 protein of bacteriophage T7 is essential for packaging of T7 DNA. T7 DNA is replicated via linear intermediates, culminating in the formation of concatemers many genomes in length which are then packaged into capsids. In infections with phage carrying amber mutations in gene 18, development is blocked at the concatemer stage. Biochemical studies on the role of gene 18 protein in concatemer processing and DNA packaging have been hampered by its low level of expression of gene 18 during T7 infections. We have cloned gene 18 on a plasmid downstream from the bacteriophage lambda PL promoter controlled by the temperature-sensitive lambda repressor encoded by c 1857. Thermal induction leads to the expression of the 10,000-Da gene 18 protein to the extent of approximately 10% of the total protein after 2 h. The overexpressed gene 18 protein is susceptible to proteolytic degradation, a condition that can be alleviated by expression in an Escherichia coli strain carrying the lon100 deletion which reduces production of protease La. Extracts of induced cells will complement an extract of T7-infected cells lacking gene 18 protein for packaging of exogenous T7 DNA. The assay has been used to monitor the purification of gene 18 protein to essential homogeneity. The identity of the purified protein has been confirmed by sequencing of the N terminus. Gel filtration analysis suggests that the native protein is an octomer. Treatment of gene 18 protein with 3 M guanidine hydrochloride denatures it to a monomer. Removal of the denaturing agent by dialysis regenerates the octomeric structure and the ability to complement packaging extracts.     

TC-83 Venezuelan equine encephalitis vaccine exposure during pregnancy

A human pregnancy exposed to TC-83 live attenuated Venezuelan equine encephalitis (VEE) virus vaccine resulted in hydrops fetalis and fetal demise. Maternal seroconversion and the finding of a diffuse mononuclear cell infiltrate on postmortem examination are suggestive of a causative role for TC-83 vaccine.     

Basic considerations in assessing and preventing occupational infections in personnel working with nonhuman primates

Transmission of zoonotic infections of nonhuman primates to human contacts is a documented occupational hazard. Although the list of naturally occurring and experimentally induced infections of nonhuman primates is extensive the risks of transmission may substantially be reduced by the use of good animal care practices, appropriate protective measures and devices, and suitable animal facilities. The essential elements of good animal care practices include high levels of personal hygiene; minimizing the creation of potentially infectious aerosols and droplets; use of personal protective clothing, devices, and vaccines; a system for reporting, evaluating, and treatment of occupational exposures and infections; and animal facilities appropriate for the species being used and the activities conducted. These essential elements are described and discussed in the context of published voluntary codes of practice--notably "Biosafety in Microbiological and Biomedical Laboratories."