Mitochondrial DNA analysis of mouse-rat hybrid cells: effect of chloramphenicol selection on the relative amounts of parental mitochondrial DNAs

Several mouse-rat somatic hybrid cell lines were isolated by fusing chloramphenicol-resistant (CAPr) and CAP-sensitive (CAPs) parent cells, and propagation of the parent mitochondrial DNA (mtDNA) species in the hybrid cells was studied. The restriction endonucleases EcoRI, HpaII, and HaeIII were used for identification of mtDNA species. Both mouse and rat mtDNAs were propagated in all the hybrid cells examined and maintained during long-term cultivation and repeated cell division. Moreover, in CAPr mouse-rat hybrid cells, selection and successive cultivation in the presence of CAP did not increase the relative amount of mtDNA species of CAPr parent cell origin, and when CAP was removed from the culture medium, mtDNA species of CAPr parent cell origin did not decrease appreciably. The amount of mouse mtDNAs was consistently 1-4 times that of rat mtDNAs inthe mouse-rat hybrid cells regardless of the species of parent cells from which the CAP resistance was derived. Thus mouse-rat hybrid cells have a stable mtDNA population in which the amount of mouse mtDNAs is larger than that of rat mtDNAs without any influence of CAP selection.

[Laboratory and clinical studies of ceftizoxime in pediatrics (author's transl)]

Laboratory and clinical studies were performed as follows on ceftizoxime (CZX), a new cephalosporin antibiotic. 1. Susceptibility of clinically isolated bacteria to CZX and cefotiam (CTM) or sulbenicillin (SBPC). Antibacterial activities of CZX and CTM were compared against S. aureus, E. coli, K. pneumoniae, E. cloacae, H. influenzae and E. aerogenes; CZX was compared with SBPC against Ps. aeruginosa. CZX and CTM were nearly equal in activity against S. aureus, but CZX was found to be more active than CTM by 1--10 tubes against E. coli, K. pneumoniae, E. cloacae, H. influenzae and E. aerogenes. Against Ps. aeruginosa, CZX and SBPC were nearly equal in activity. 2. Serum concentration and urinary recovery. Serum concentrations of CZX were measured in 6 patients given CZX for prophylactic purpose during cardiac catheterization. In 2 patients given 20 mg/kg of CZX intravenously, the average serum concentration was 38.9 micrograms/ml at 30 minutes after intravenous bolus injection. In 3 patients given 10 mg/kg of CZX by intravenous drip infusion, the peak average serum concentration was 28.1 micrograms/ml at the end of infusion. Urinary recovery in 2 patients tested was 81.1% and 92.5% until 6--7 hours after intravenous bolus injection. 3. Clinical efficacy. CZX was given intravenously to 24 patients in doses of 30--111 mg/kg (57.1 mg/kg on an average) t.i.d. or q.i.d. for 3--16 days (5.5 days on an average): 1 with lacunar tonsillitis, 4 with acute bronchitis, 12 with pneumonia, 2 with enterocolitis, 2 with soft tissue infection, 2 with lymphadenitis and 1 with UTI. The overall efficacy rate was 95.8%, i.e., efficacy was excellent in 10 (41.7%), good in 13 (54.2%), and poor in 1 (4.2%). Bacteriological efficacy was excellent, i.e. 21 of the 23 strains disappeared. One patient had mild and transient diarrhea, but no other laboratory abnormalities were observed during treatment. The above results suggest that CZX is 1 of the most useful antibiotics for treating pediatric infections, especially due to Gram negative bacteria.

[Clinical experience with cefroxadine in bacterial infection of children (author's transl)]

In order to evaluate effectiveness of cefroxadine (CXD) in the treatment of bacterial infections of children, the clinical studies were carried out. CXD was orally administered to 30 patients at daily dose of 27.5 approximately 50.0 mg/kg (average 32.3 mg/kg) in 3 approximately 4 divided dose for 3 approximately 10 days (average 4.9 days). The overall efficacy rate in 30 cases was 93.3%, i.e., excellent 22 (73.3%), good in 6 (20.0%), fair in 1 (3.3%) and poor in 1 case (3.3%). Drug eruption and transient eosinophilia were observed in 1 case each out of 30 cases (6.7%), but any other abnormality was not observed throughout this series. Based on the above results, CXD was thus considered to be a useful antibiotic in treatment of pediatric infections.

Purification of cytoplasts (enucleated cells) and karyoplasts (nuclei) from mouse splenic lymphocytes with cytochalasin-B

Murine spleen and lymphoma cells were almost completely enucleated in suspension by centrifugation in discontinuous Ficoll gradients in the presence of cytochalasin-B. Viability of cytoplasts (cells lacking nuclei) and karyoplasts (nuclei) was over 90%. Pure fractions of cytoplasts or karyoplasts were then obtained by fractionation of the cytochalasin-B treated cells with unit gravity sedimentation in bovine serum albumin. Protein synthesis was seen in cytoplasts when they were stimulated with mitogens, such as lipopolysaccharide (LPS). This method can consistently yield pure fractions of morphologically and functionally intact karyoplasts or cytoplasts from normal lymphocytes with very low contamination of nucleated cells. Pure karyoplasts or cytoplasts obtained in this way could be extremely useful for subcellular analysis of lymphocyte activation.

[Clinical experience with cefoxitin in bacterial infections of children (author's transl)]

Using a new cephamycin antibiotic, cefoxitin, clinical studies were carried out, and the following results were obtained: (1) Cefoxitin was administered to 52 children with 38 respiratory tract infections, 2 urinary tract infections, 1 acute otitis media and others, who ranged in age from 2 months to 11 years old. (2) Cefoxitin was given intravenously at a daily dose of 27.3 mg/kg to 110.5 mg/kg. (3) The overall efficacy rate was 80% in 46 cases, i.e., excellent in 10, good in 27, fair in 7 and poor in 2. (4) Clinical side effects were not seen except exanthema in 1 patient. Elevation of GOT and GPT was seen in 2 patients, elevation of A1-P in 1 and eosinophilia in 2 by laboratory tests. However, these findings were alleviated rapidly following the cessation of therapy.

Evaluation of the time weighted average of air contaminants with special references to concentration fluctuation and biological half time

Statistical parameters with carbon felt dosimetry are analyzed and new sampling criteria are presented based on the analysis. In cass where the mean of measured time-weighted averages is kept two times the unbiased standard deviation below the maximum permissible concentration-time weighted average (MPC-TWA) and the values above MPC-TWA are observed with a frequency of less than 5%, compliance is determined with a confidence limit of 95% provided the biological half time of the contaminant is longer than 4 hours.

Comparison of effects of external Ca2+ on antioxytocin actions of antispasmodics in ovariectomized and estradiol-treated rat uteri

The influence of Ca2+ on the antioxytocin actions of papaverine, deoxycholate and 1,1-diphenyl-3-piperidinobutanol hydrochloride (Aspaminol) was investigated in the ovariectomized and the estradiol-treated rat uteri, and Ca exchangeability and Ca content in both uteri were compared. No qualitative difference in the responses to deoxycholate and Aspaminol at normal and higher Ca2+ concentrations in the estradiol-treated rat uterus was seen as compared to those obtained from the ovariectomized one. The antioxytocin action of papaverine in the estrogenized uterus was antagonized by excess external Ca2+, but not in the ovariectomized one. There were no significant differences either in the total Ca content or the non-displaceable Ca by La between the ovariectomized and the estrogenized rat uterine longitudinal muscle layers, while Ca exchangeability in the estrogenized was much greater than that in the ovariectomized one. These results suggest that the antagonism of papaverine against exogenous Ca2+ may be related to the more increased Ca exchangeability in the estradiol-treated rat myometrium.

Mechanism of gastroesophageal reflux in recumbent asymptomatic human subjects

We investigated the mechanism of gastroesophageal reflux (GER) in 10 health volunteer subjects. Continuous recordings of intraluminal esophageal pH and pressure were obtained on two consecutive nights from 6:00 p.m. to 6:30 a.m. in each subject. During each study, the subject remained recumbent, except to eat a standardized meal after 1 h of basal recording. A manometric assembly with seven recording lumens monitored: (a) lower esophageal sphincter (LES) pressure via a sleeve device 6.5 cm in length, (b) esophageal-body motor activity, (c) swallowing activity in the pharynx, and (d) gastric pressure. An electrode 5 cm above the LES recorded esophageal pH. Sleep was monitored by electroencephalogram. All subjects showed wide variations of basal LES pressure. GER was not related to low steady-state basal LES pressure, but rather occurred during transient 5-30 s episodes of inappropriate complete LES relaxation. The inappropriate LES relaxations were usually either spontaneous or immediately followed appropriate sphincter relaxation induced by swallowing. The majority of GER episodes occurred within the first 3 h after eating. During the night LES relaxation and GER occurred only during transient arousals from sleep or when the subjects were fully awake, but not during stable sleep. After GER the esophagus was generally cleared of refluxed acid by primary peristalsis and less frequently by secondary peristalsis. Nonperistaltic contractions were less effective than peristalsis for clearing acid from the esophagus. We conclude that in asymptomatic recumbent subjects GER is related to transient inappropriate LES relaxations rather than to low steady-state basal LES pressure and also, that primary perstalsis is the major mechanism that clears the esophagus of refluxed material.

Basis of thermostability in pig heart lactate dehydrogenase treated with O-methylisourea

Acetamidination of pig heart lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) with ethyl acetimidate resulted in an increase of thermostability, and covalent bridge formation between pairs of lysine residues is observed. Guanidination with O-methylisourea of the enzyme also increases the thermostability, but such a bridge seems not to be formed. Increased thermostability of guanidinated enzyme is considered to be due to the shift of the pK values of the lysine residues from 10.5 to 12.5 after guanidination. Modification experiments with carbodiimide reveals that the enzyme contains 4.6 pairs of neighboring lysine and carboxyl residues per subunit, and amide bonding between 3.2 pairs results in an increase of thermostability. Guanidination of 4.6 Lys/subunit of the enzyme yields an enzyme derivative with considerably increased thermostability. Salt bridge formation between the 4.6 pairs of neighboring carboxyl and guanidinated lysine residues per subunit might make a major contribution to the increased thermostability of the guanidinated enzyme.

Assessment of fracture healing by vibration

The wave signal from percussion of a bone (i.e. percussion-note) has been used to evaluate the extent of bony consolidation after fracture. Forty-one cases with a fresh tibial fracture and eight cases of delayed union of the tibia were investigated. The medial malleolus of the tibia was struck with a tapper and the vibration signal was picked up at the medial region of the tibial tuberosity. The changes in the signal waveform of the percussion-note with time were investigated. As healing proceeds, the signal waveform of the fractured bone approaches that of intact bone. In cases of delayed union, the character of the wave does not improve sufficiently with time. The authors are convinced that this is a promising new method for the early diagnosis of delayed union.

Cross-linking with diimidates of glutamine synthetase from Bacillus stearothermophilus

Glutamine synthetase [EC 6.3.2.1] from Bacillus stearothermophilus was modified with diethyl malonimidate (DEM), dimethyl adipimidate (DMA), and dimethyl suberimidate (DMS). DMA modified most epsilon-amino groups. On modification with DMA, formation of 3 to 4 cross-links/subunit resulted in a large increase in thermostability. The activity, allosteric properties and fluorescence spectrum of the enzyme were not changed on cross-linking. The SDS-polyacrylamide gel electrophoretic profiles of DEM-, DMA-, and DMS-modified enzymes suggested that the interaction berween six subunits in each of the two hexagonal rings of the protein are heterologous and are different from those between the piled subunits on different rings.

Chemical modification of epsilon-amino groups in glutamine synthetase from Bacillus stearothermophilus with ethyl acetimidate

The activity of glutamine synthetase [EC 6.3.2.1] from Bacillus stearothermophilus decreased slightly on modification with ethyl acetimidate. Acetamidination of 25--26 of the 2 epsilon-amino groups/subunit of the enzyme affected the maximum velocity, but not the Michaelis constant. The thermostability of the enzyme was considerably increased on acetamidination. Acetamidination of the enzyme did not affect the circular dichroism, the tryptophan fluorescence or the quenching effects of KI and acrylamide on the tryptophan emission. The fluorescence spectrum of p-toluidinylnaphthalene sulfonate bound to the enzyme changed on acetamidination.

DNA content of microcells prepared from rat kangaroo and mouse cells

Enucleation of animal cells in which nuclear fragmentation (micronucleation) has been induced by treatment with mitotic inhibitors results in the formation of subdiploid microcells consisting of one or several micronuclei, some cytoplasm and surrounded by a plasma membrane. Microcells were prepared from rat kangaroo cells (12 chromosomes) and a polyoma virus transformed mouse cell line (61 chromosomes) and analysed for DNA content. Microspectrophotometric DNA measurements and the appearance of micronuclei at mitosis show that small micronuclei contain genetic information equivalent to single chromosomes. A large proportion of the micronuclei and the microcells, however, contains DNA corresponding to several chromosomes. Heterogeneous mixtures of microcells can be fractionated by a unit gravity sedimentation procedure so as to isolate the small microcells. These can afterwards be fused with intact normal or mutant cells.

Confirmation of the assignment of the Chimpanzee thymidine kinase and galactokinase genes to chromosome 19

Chimpanzee-mouse hybrid cells were isolated by fusing chimpanzee HGPRT- cells and mouse TK- cells. Both biochemical and cytologic studies of these hybrid cells and BUDR resistant cells isolated from them showed that the TK and GaK genes are located on the chimpanzee chromosome 19.

ATP and acetylene-reducing activity of a sulfate-reducing bacterium

A sulfate-reducing bacterium, a strain of Desulfovibrio vulgaris, when lactate or pyruvate was supplied as an electron and energy source, reduced acetylene only in the presence of sulfate. Acetylene reduction started after a lag of 1 h. H2 which acts as an electron and energy source for sulfate reduction was unable to reduce acetylene even in the presence of sulfate. It was suggested, from the measurements of the amounts of adenine nucleotides of the bacterium incubated under various conditions, that the bacterium is able to reduce acetylene at a high ATP level or a high ATP/ADP ratio.

Acidostability of speroplasts prepared from Thiobacillus thiooxidans

Thiobacillus thiooxidans was acidostable even in the absence of its respiratory substrate, elementary sulfur. This suggests that the acidostability of the bacterium was enery-independent. The organism was subjected to osmotic shock with 0.75 M sucrose at 0 degrees C and then treated with snail intestinal juice in the presence of 0.3 M sucrose. The decrease in the optical density of the sample thus prepared on dilution with deionized water and electron microscopic observation of the sample showed that spheroplasts were formed from the bacterium by this procedure. Spheroplasts were able to respire sulfur and their respiratory activity was acidostable. Spheroplasts, when treated with Nagase, proteolytic enzyme, lost their acidostability, and some protein components disappeared from the membrane fraction. This suggests that the acidostability of the bacterium may be related to protein conponents of the membrane.

Effect of temperature on the viability of Bacillus stearothermophilus

One of the obligate thermophilic bacteria, Bacillus stearothermophilus, was unable to grow at temperatures below 35 degrees C. About 80% of the population in the bacterial culture died at the temperatures, and the same extent of loss in either of the activities of oxygen consumption or synthesis of protein or nucleic acid of the organisms was observed. With the progress of death of the organisms, reduced nicotinamide-adenine dinucleotide came to be oxidized by the organisms, enzymes such as fructose-1,6-diphosphate aldolase, when the organisms were washed with phosphate buffer, were leaked out of the organisms, and an increasing amount of ribonucleoprotein was released into the culture medium. The change of the membrane state was then suggested to be one of the possible causes for the death of the organisms at the temperatures.