Low Interferon Relative-Response to Cytomegalovirus Is Associated with Low Likelihood of Intrauterine Transmission of the Virus

Background

Congenital Cytomegalovirus (CMV) is a very common intrauterine infection which can cause severe mental and hearing impairments. Notably, only 40% of primarily infected women transmit CMV to the fetus. CMV-specific T-cell response has a role in CMV disease but individual immune heterogeneity precludes reliable correlation between measurable T-cells response and intrauterine transmission.

Study Aim

To establish a correlation between maternal T-cells response and fetal CMV transmission using an individual normalized immune response.

Methods

We analyzed IFN-γ secretion upon whole blood stimulation from primary CMV-infected pregnant women, with either CMV-peptides or PHA-mitogen.

Results

We established a new normalization method of individual IFN-γ response to CMV by defining the ratio between specific-CMV response and non-specific mitogen response (defined as IFN-γ relative response, RR), aiming to overcome high person-to-person immune variability. We found a unique subpopulation of women with low IFN-γ RR strongly correlated with absence of transmission. IFN-γ RR lower than 1.8% (threshold determined by ROC analysis) reduces the pre-test probability of transmission from 40% to 8%, revealing an unexpected link between low IFN-γ RR and non-transmission.

Conclusion

In pregnant women with primary CMV infection, low IFN-γ RR is associated with low risk of transmission.     

Chlorophyllase activity in chlorophyll-free citrus chromoplasts

Chromoplast fractions from mature, chlorophyll-less ‘Valencia’ orange (Citrus sinensis L. Osbeck) flavedo (= the outer coloured layer of citrus peel) showed considerable chlorophyllase activity. Acetone powders prepared from chromoplast fractions had 2.5× higher specific activity than those prepared from whole flavedo. Exposure of mature, chlorophyll-less fruit to ethylene caused a 2.5 to 4.0 fold increase in chlorophyllase activity. Juice chromoplasts showed negligible chlorophyllase activity. The results suggest that chlorophyllase activity as well as its induction by ethylene are not dependent upon the presence of chlorophyll in the tissue.     

Regulative Systems in the Developing Citrus Fruit I. The Hormonal Balance in Orange Fruit Tissues

The regulative systems of auxins, gibberellin-like substances and their inhibitors in citrus fruit were studied. Masking caused by a high content of inhibitors was eliminated by using a refined method of solvent partition. Considerable amounts of auxins and gibberellin-like substances were detected in all stages of fruit development. The auxin system of the citrus fruit is highly complex and consists of various elements which undergo dynamic changes throughout the growth period. The identity of the auxins was studied using IAA-2-¹⁴C, and 88% of the radioactivity specifically migrated into the etheric pH 6.0 fraction. Although the prominent zones of promotion do not coincide with IAA, it can be concluded that the auxin promoters are probably not the “citrus auxin”. Abscisic acid-like inhibitors were found to accumulate in the external layers of the fruit, increasing in content as time advances.     

Effects of SH group reagents on creatine kinase interaction with the mitochondrial membrane

Solubilization of the specific mitochondrial isoenzyme of creatine kinase (CKm) from rabbit heart mitochondria by treatment with SH group reagents has been studied. From the various compounds tested only the negatively charged organomercurials are able to induce an extensive solubilization of the enzyme. This effect is fully reversible since the solubilized enzyme readily reassociates with the membrane when the bound organomercurial is removed by treatment of the homogenate by an excess of dithiothreitol. Solubilization by negatively charged organomercurials can be partly prevented by pretreatment of mitochondria with either disulfide or uncharged organomercurials. No clear-cut relationship has been pointed out when the amount of SH titrated by various reagents has been compared with the extent of CKm solubilization. More detailed studies with para-chloromercuribenzoate (pCMB) show that extensive CKm solubilization (about 75%) occurs for pCMB concentration as low as 25 microM, whereas pronounced inhibition of the enzyme is observed only for concentrations greater than 200 microM. By cross-reassociation of enzyme solubilized either by para-hydroxymercuribenzoate (pHMB) or by 20 mM sodium phosphate (NaPi) with mitochondria depleted of CKm by pHMB or by NaPi treatment, SH groups whose titration impedes CKm reassociation with the mitochondrial membrane have been tentatively located on the enzyme. Thus, negatively charged organomercurials, could induce a reversible conformational modification of the enzyme which is no longer able to bind on the inner mitochondrial membrane. Furthermore, our results show that the binding of an excess of mitochondrial CK, which has been previously reported, could reflect unspecific binding since it occurs only on mitoplasts incubated in very hypotonic medium, but not in isotonic medium.     

Extraction of Auxin and of Other Growth Regulators from Citrus Steins by Centrifugal Force

A method is described whereby diffusible native growth substances are forcibly extracted by centrifugation. Centrifugates are relatively pure, highly active when tested for auxins and gibberellins, and contain far less inhibitors than solvent extracts.     

The auxin induced curvature of citrus petals

The curvature of citrus petals was studied, using petals implanted in an agar-sucrose medium. Applications of indoleacetic acid and p-chlorophenoxyisobutyric acid and determinations of endogenous auxins indicate that the bending of citrus petals is an auxin-mediated process.     

Native growth inhibitors from citrus shoots. Partition, bioassay, and characterization

A partition method has been devised to separate auxins, gibberellins, and their respective inhibitors in plant extracts. Inhibitors counteracting gibberellin activity have been detected by a modified barley endosperm bioassay. An inhibitor found in young citrus shoots counteracts both auxin and gibberellin activities and behaves during partition and ohromatography like abscisin II.     

Jur. Philiptschenko

Ohne Zusammenfassung     

Chelation effects on Azotobacter cells and cysts

Goldschmidt, Millicent C. (University of Texas, Austin), and Orville Wyss. Chelation effects on Azotobacter cells and cysts. J. Bacteriol. 91:120-124. 1966.-Ethylenediaminetetraacetate (EDTA) is very toxic to Azotobacter in the presence of nitrogen compounds that form complexes with it. This appears to be due to stronger chelation of certain metal ions by the complex. When such complexes of EDTA and nitrogen compound are absent, Azotobacter cysts can be ruptured by chelation without being killed. The lethal action as well as the cyst rupture is modified by the presence of salts.