Transitory hematologic effects of moderate exercise are not influenced by iron supplementation

A young women's exercise/fitness class tested the idea that administration of supplemental iron would prevent "sports anemia" that may develop during exercise and training and improve iron status of exercising females of menstrual age. Fifteen women (aged 18-37) were selected for each of three treatment groups: (1) no supplemental iron; (2) 9 mg X d-1 of Fe; and (3) 18 mg X d-1 of Fe (1 US Recommended Daily Allowance). Women exercised at approximately 85% of maximal heartrate for progressively increasing lengths of time in a jogging program and worked up to 45 min of exercise 4 d X week-1 for 8 weeks. Hematologic analysis was performed in weeks 1, 5, and 8. A significant decline in hemoglobin (Hb) concentration and hematocrit (Hct) was observed at week 5 when all data were examined without regard for iron intake; these red cell indices returned to pre-exercise levels by week 8. Reduction of mean cell hemoglobin concentration (MCHC) indicated that the midpoint decline was not caused by simple hemodilution during exercise. Serum ferritin (SF) concentration changed in parallel with Hb and Hct. Although the midpoint decline in SF was not statistically significant, it ruled out the possibility that turnover of red cell iron was directed to storage. Lowered MCHC and SF suggested lower availability of iron during the synthesis of a new generation of red cells. Few iron treatment effects of magnitude were observed. Iron did not prevent the midpoint decline in Hb concentration. Iron intake did not affect SF, serum iron, transferrin saturation, or final Hb, and Hct.(ABSTRACT TRUNCATED AT 250 WORDS)     

Laboratory rearing ofPeridesmia discus on irradiated alfalfa weevil eggs

A method for the rearing ofPeridesmia discus (Walker) (Hymenoptera: Pteromalidae) on eggs of alfalfa weevil,Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) with 5.0 Krads of gamma radiation is described. Using this procedure 21 P₁ P. discus produced an F₁ of 129 individuals and a group of F₁ adults yielded 172 F₁ P. discus. Depending on temperature the range of developmental times average from 12.5 to 28.8 days. Productivity of the technique was limited by the egg output of the alfalfa weevil culture and the original number ofP. discus available.     

Inactivated Eastern Equine Encephalomyelitis Vaccines Prepared in Monolayer and Concentrated Suspension Chick Embryo Cultures

Eastern equine encephalomyelitis vaccines were prepared with virus propagated in stationary monolayer cultures and in concentrated suspension cultures of primary chick embryo cells. Virus pools for vaccine preparation were inactivated by three different methods: 0.05% formalin, 41 C heat, and 0.16% beta-propiolactone. Heat-and beta-propiolactone-inactivated vaccines maintained high hemagglutinating titers in the fluid state for at least 10 months, whereas formalin-inactivated vaccines lost their hemagglutinating activity within a few hours after treatment. The hemagglutinin of beta-propiolactone-inactivated virus particles was more dense than the hemagglutinin of the parent virus particles, as determined by sucrose density gradient centrifugation. The increase in density may be due to the degradation or removal of the lipid from the virus envelope. When administered to guinea pigs, all three vaccines stimulated hemagglutination-inhibiting, complement-fixing, and neutralizing antibodies and afforded protection against a live virus challenge. Test results showed that vaccines prepared with virus propagated in concentrated suspension cultures were more immunogenic and stimulated greater serologic responses in guinea pigs than vaccines derived from monolayer-propagated virus. The beta-propiolactone-inactivated vaccine was most protective, the heat-inactivated (41 C) vaccine next, and the formalin-inactivated vaccine least potent.     

Quantitative Nasal Culture: a Tool in Antibiotic Research

The use of the quantitative nasal culture was investigated as a means of evaluation of new antimicrobial drugs in man. Cyclacillin was somewhat more active in vitro than penicillin G against penicillin G-resistant organisms. Cyclacillin was highly effective in suppressing staphylococci susceptible to penicillin G in nasal carriers but did not suppress staphylococci resistant to penicillin G. Although in previous studies by others cyclacillin was effective in treating mice infected with penicillin G-resistant staphylococci, in the present studies cyclacillin was not effective in suppressing nasal penicillin G-resistant staphylococci in man at doses which markedly suppressed penicillin G-sensitive organisms.     

Deoxyribonucleic Acid Replication in Simian Virus 40-Infected Cells IV. Two Different Requirements for Protein Synthesis During Simian Virus 40 Deoxyribonucleic Acid Replication

The replication of simian virus 40 (SV40) deoxyribonucleic acid (DNA) was inhibited by 99% 2 hr after the addition of cycloheximide to SV40-infected primary African green monkey kidney cells. The levels of 25S (replicating) and 21S (mature) SV40 DNA synthesized after cycloheximide treatment were always lower than those observed in an infected untreated control culture. This is consistent with a requirement for a protein(s) or for protein synthesis at the initiation step in SV40 DNA replication. The relative proportion of 25S DNA as compared with 21S viral DNA increased with increasing time after cycloheximide treatment. Removal of cycloheximide from inhibited cultures allowed the recovery of viral DNA synthesis to normal levels within 3 hr. During the recovery period, the ratio of 25S DNA to 21S DNA was 10 times higher than that observed after a 30-min pulse with (3)H-thymidine with an infected untreated control culture. The accumulation of 25S replicating SV40 DNA during cycloheximide inhibition or shortly after its removal is interpreted to mean that a protein(s) or protein synthesis is required to convert the 25S replicating DNA to 21S mature viral DNA. Further evidence of a requirement for protein synthesis in the 25S to 21S conversion was obtained by comparing the rate of this conversion in growing and resting cells. The conversion of 25S DNA to 21S DNA took place at a faster rate in infected growing cells than in infected confluent monolayer cultures. A temperature-sensitive SV40 coat protein mutation (large-plaque SV40) had no effect on the replication of SV40 DNA at the nonpermissive temperature.     

Linear, Single-Stranded Deoxyribonucleic Acid Isolated from Kilham Rat Virus

Kilham rat virus (KRV) was grown in a rat nephroma cell line and was purified by two isopycnic centrifugations in cesium chloride. The virus contains single-stranded deoxyribonucleic acid (DNA) with a molecular weight of approximately 1.6 x 10(6). The DNA was extracted from the virion by both phenol extraction and by 2% sodium dodecyl sulfate at 50 C. KRV DNA, extracted by both procedures, was observed in an electron microscope by using a cytochrome c or diethylaminoethyldextran monolayer. The DNA was also exposed to exonuclease I, an enzyme which hydrolyzes specifically linear, single-stranded DNA. Hydrolysis of 70 to 80% of the DNA was observed. Both the enzymatic and the electron microscope studies support the conclusion that extracted KRV DNA is a single-stranded, linear molecule. The length of the DNA was measured in the electron microscope and determined to be 1.505 +/- 0.206 mum.     

Effect of Temperature on the Fatty Acid Composition of Thermus aquaticus

Thermus aquaticus contains four major fatty acids, iso-C(15) (28%), iso-C(16) (9%), normal-C(16) (13%), and iso-C(17) (48%), when grown at 70 C, as determined by gas chromatography and mass spectrometry. Small amounts of iso-C(12), normal-C(12:1), iso-C(13), normal-C(14), iso-C(14), and normal-C(15:1) were also detected. A change in growth temperature (50 to 75 C at 5-C intervals) affects a shift in the proportions of some of the fatty acids. The proportions of the monoenoic and branched-C(17) fatty acids decreased and the proportions of the higher-melting iso-C(16) and normal-C(16) fatty acids increased. Cells grown at 75 C contained 70% more total fatty acids than cells grown at 50 C. The largest increases, in absolute amounts, were in the content of iso-C(16) and normal-C(16) fatty acids, with only a 1.6-fold increase in the major iso-C(15) and iso-C(17) fatty acids. There was a 2.5-fold decrease in normal-C(15:1) and at least a 24-fold decrease in anteiso-C(17), which is present at 50 and 55 C but not at higher temperatures. There was no difference in proportion or amount of fatty acids between exponential and stationary-phase cells grown at 70 C. When cells were grown on glutamate instead of yeast-extract and tryptone at 70 C, the total fatty acid content remained constant, but there was an increase in the proportions of iso-C(16) and normal-C(16) fatty acids concomitant with a decrease in the proportions of the iso-C(15) and iso-C(17) fatty acids.     

THE PERMEABILITY OF PINCHED-OFF NERVE ENDINGS TO SODIUM, POTASSIUM AND CHLORIDE AND THE EFFECTS OF GRAMICIDIN

Abstract—

• 1 The passive permeability of synaptosomes to ions was measured by a light-scattering technique. Synaptosomes were freely permeable to acetate, HCO₃^_, SCN^?and NH₄⁺ and were impermeable to choline and SO₄^2-.
• 2 Gramicidin D selectively increased the permeability of synaptosomes to Na⁺ and K⁺ ions.
• 3 The relative permeabilities of Na⁺, K⁺ and Cl^?, measured in the presence of a number of more permeant counter-ions, was in the ratio 1:19:12. These values are discussed in terms of the source of the resting potential.