A new boronate ester-based crosslinking strategy allows the design of nonswelling and long-term stable dynamic covalent hydrogels.

Dynamic hydrogels are viscoelastic materials that can be designed to be self-healing, malleable, and injectable, making them particularly interesting for a variety of biomedical applications. To design dynamic hydrogels, dynamic covalent crosslinking reactions are attracting increasing attention. However, dynamic covalent hydrogels tend to swell, and often lack stability. Boronate ester-based hydrogels, which result from the dynamic covalent reaction between a phenylboronic acid (PBA) derivative and a diol, are based on stable precursors, and can therefore address these limitations. Yet, boronate ester formation hardly occurs at physiological pH. To produce dynamic covalent hydrogels at physiological pH, we performed a molecular screening of PBA derivatives in association with a variety of diols, using hyaluronic acid as a polymer of interest. The combination of Wulff-type PBA (wPBA) and glucamine stood out as a unique couple to obtain the desired hydrogels. We showed that optimized wPBA/glucamine hydrogels are minimally- to non-swelling, stable long term (over months), tunable in terms of mechanical properties, and cytocompatible. We further characterized their viscoelastic and self-healing properties, highlighting their potential for biomedical applications.

Challenge of BALB/c mice with respiratory syncytial virus does not enhance the Th2 pathway induced after immunization with a recombinant G fusion protein, BBG2NA, in aluminum hydroxide.

The polypeptide of aa 130-230 of the G protein (G2Na) of respiratory syncytial virus (RSV) was fused to BB, the albumin-binding region of streptococcal G protein, producing BBG2Na, which induced protective immune responses in rodent models. Evaluation of the immune response in mice immunized with BBG2Na in the adjuvant alhydrogel revealed high amounts of interleukin (IL)-5 and some IL-4 in splenocytes restimulated in vitro. This is compatible with a Th2 response. The activation of the Th2 pathway in such mice was further supported by the detection of IL-5 and G2Na-specific IgE in vivo. Of interest, in contrast to immunization with formalin-inactivated RSV, immunization of mice with BBG2Na followed by intranasal RSV challenge did not lead to increased production of IL-5- or G2Na-specific IgE. However, IgG1- and IgG2a-specific antibodies were boosted. These results demonstrate that the Th2 pathway is not enhanced by RSV challenge in BBG2Na-immunized mice.

Incorporation of Oxygen into Glycolate, Glycine, and Serine during Photorespiration in Maize Leaves.

Glycolate, glycine, and serine extracted from excised Zea mays L. leaves which had been allowed to photosynthesize in the presence of (18)O(2) were analyzed by gas chromatography-mass spectrometry. In each case, only one of the oxygen atoms of the carboxyl group had become labeled. The maximum enrichment observed in glycine and serine was attained after 5 minutes and 15 minutes of exposure to (18)O(2) at the CO(2) compensation point; the labeling was very high, reaching 70 to 73% of that in the applied O(2). Thus, it appears that all or nearly all of the glycine and serine are synthesized in maize leaves via fixation of O(2). In the presence of CO(2) (380 or 800 microliters per liter), (18)O-labeling was markedly slower.Glycolate enrichment was variable and much lower than that in glycine and serine. It is possible that there are additional pathways of glycolate synthesis which do not result in the incorporation of (18)O from molecular oxygen. An estimation of the metabolic flow of O(2) through the photorespiratory cycle was made. It appeared that less than 75% of the O(2) taken up by maize leaves is involved in this pathway. Therefore, other processes of O(2) metabolism must occur in the light.

Comparison of enzyme-linked immunosorbent assay (ELISA) and complement fixation test for detection of Mycoplasma pneumoniae antibodies.

An enzyme-linked immunosorbent assay (ELISA) for the detection of IgG and IgM antibodies against Mycoplasma pneumoniae, performed with commercial antigen and reagents, is compared with the complement fixation test (CF) in a serological study of 209 human sera. Concordant results were usually obtained by CF test and by IgG ELISA in sera from patients with recent M pneumoniae infection. In contrast, when used for an immunological survey of a general population, approximately 27% of the sera negative in the CF test were positive for IgG by the ELISA, and sera with low CF titres were found to have a broad range of IgG titre by the ELISA. This may be due to the greater sensitivity of the ELISA technique and/or to different types of antibody measured by both tests. IgM was detected by ELISA in sera from all patients with recent M pneumoniae infection diagnosed on the basis of clinical findings and by CF assay. Occasionally false-positive IgM antibodies were due to rheumatoid factor (RF); this potential interference necessitates routine testing of IgM antibody positive sera for RF.

Immune adherence hemadsorption: specific method for rapid identification of adenovirus antigens.

An immune adherence hemadsorption test for the rapid group-specific identification of adenoviruses is described. The test was performed directly on the cell culture isolate in less than 1 h, by the sequential addition of the antiserum of any adenovirus serotype, complement, and then C3b receptor-rich human erythrocytes. Microscopic examination revealed the presence of erythrocytes adhering firmly to the infected cell sheet. The immune adherence hemadsorption test proved a specific and rapid diagnostic procedure for the detection of adenovirus group antigen in tissue cultures and was more simple than conventional tests.

Modification of steroidogenesis in a mouse adrenal cell line (Y-1) transformed by simian adenovirus SA-7.

Transformation of a steroidogenic mouse adrenal cell line (Y-1) by simian adenovirus SA7 produced a cell line with low apparent steroidogenic activity. The effect of ACTH and cholera toxin on cyclic AMP production was similar in both not transformed and virus-transformed cells and activity of cyclic AMP-dependent protein kinase was also similar in both cells. In transformed cells, cholesterol was metabolized to delta 5-3 beta-hydroxysteroids, mainly 20 alpha-dihydropregnenolone while in not transformed cells, the major metabolites were delta 4-3 ketosteroids (20 alpha-dihydro- and 11 beta-hydroxy-20 alpha-dihydroprogesterone). In both cell lines ACTH increased the metabolism of cholesterol. Further studies with labelled pregnenolone and progesterone revealed a loss of delta 5-3 beta-hydroxysteroid dehydrogenase/isomerase and 11 beta-hydroxylase activity in the transformed cells.

Properties of simian adenovirus 7 after one single passage in simian marmoset lymphoblastoid cells transformed by Epstein Barr virus.

Simian adenovirus 7 gave an abortive infection in simian marmoset lymphoblastoid cells, B 95-8 and M 81 (transformed by Epstein Barr Virus) whereas non transformed simian lymphocytes could not replicate this virus. Electron dense incomplete particles with a lower density than standard virus in CsCl gradients were isolated. Virus yields were low and the percentage of cells containing viral antigen as measured by immunofluorescence was 0.01% for B 95-8 cells and still less for the M 81 cells. After a single passage in either lymphoblastic cell lines, they had a reduced oncogenicity in vivo. The polypeptide pattern analysis by PAGE showed some modifications.

Hemagglutination inhibition, single radial hemolysis, and ELISA tests for the detection of IgG and IgM to rubella virus.

Hemagglutination inhibition (HI), single radial hemolysis (SRH) and enzyme-linked immuno sorbent assay (ELISA), performed with commercial antigen and reagents are described and were compared in the three distinct situations that require rubella antibody detection. Determination of immunity status was carried out on 156 sera. A degree of correlation greater than 0.9 was found when comparing the three methods. Analysis of a further 74 sera, from 31 primary infections and three congenital syndromes, was performed to compare the occurrence of the various classes of antibodies in the three tests: HI test and IgM-ELISA become positive the day after the rash, whereas SRH test is not positive before the sixth day. From our limited study bearing on a total of 230 sera, each test has a precise assignment. For the determination of immunity status, SRH is simpler, faster, and inexpensive; absence or evidence of past infection can be unequivocally obtained especially in cases of low (1:10, 1:20) residual immunity. In the serodiagnosis of a rubella rash, SRH alone, due to the delayed rise in antibody titers, will demonstrate a complete seroconversion with a first serum collected up to the fifth day of the eruption. In case of absence of an early serum, of primary infection in a pregnant woman, of a newborn with suspicion of congenital syndrome, the measurement of rubella specific IgM is best obtained with ELISA, a procedure less time-consuming than HI following centrifugal, chromatographic, or electrophoretic separation, and "light" (8 S) RF with SRH test is discussed. Interference of IgM Rheumatoid Factor (RF) with IgM ELISA and IgG RF with SRH test is discussed.

[The bacteriological diagnosis of pneumonia by transtracheal puncture. Value in medical intensive care (author's transl)]. / Diagnostic bactériologique des pneumonies par ponction transtrachéale. Intérêt en réanimation médicale.

Seventy five patients referred with a diagnosis of pneumonia underwent transtracheal puncture. In 76% of cases this examination led to discovery of an organism in infected patients. In 50% of cases, the bacteriological diagnosis was sufficiently accurately oriented by direct examination to permit rapid and effective treatment. There was virtually perfect agreement with the results of blood cultures when the latter were positive. The organisms most often responsible were Gram positive and above all the pneumococcus. These results led to narrow spectrum antibiotic treatment appropriate for the organism. This early treatment, based upon the results of tracheal puncture, was associated with a favourable course in 85% of cases, in particular in severely ill patients requiring intubation. No notable complications occurred.

[Hemagglutination by simian adenovirus 7]. / Hémagglutination par l'adénovirus simien 7.

Simian adenovirus 7, either complete virus or its capsid subunits, agglutinates Rat (Sprague-Dowley) red blood cells in the presence of heterotypical antiserum. Haemagglutination takes place at 4 degrees C and room temperature. The antigen could not be eluted and its haemagglutinin properties are heat-stable. The reaction is specific. It is inhibited by homologous antiserum only. This property and its characteristics permit a camparison of this strongly oncogenic adenovirus to the human adenovirus of subgroup III of Rosen.

[Use of hemolysis in gel in the serodiagnosis of rubella. Comparison with hemagglutination inhibition]. / Application de l'hémolyse en gel au sérodiagnostic de la rubéole. Comparaison avec l'inhibition d'hémagglutination.

The hemolysis in gel test (HIG) was compared with the hemagglutination inhibition test (HI). This new test is simple and time-sparing since it does not require dilution or serum pre-treatment, and can be measured directly in mm. It is not more expensive than the HI method. It has proved sensitive and is not affected by non specific serum hemagglutination inhibitors and is conclusive whenever HI titers are looked upon with suspicion (titers of less than 1/20). It is therefore well adapted to mass screening of immunity against rubella but in the field of recent infections HI method still has its role to play. Using the HIG test as a reference, we measured the loss of Ig to rubella following the three most commonly employed methods for removal of inhibitors: the mean values of 16 sera were 25% of antibodies lost after kaolin pre-treatment, 62% lost after heparine-Mn-Cl2 procedure 75% lost after dextran-CaCl2 treatment.

[Loss of steroidogenesis in a mouse adrenal cell line after simian adenovirus 7 (SA7) transformation]. / Perte de la stéroïdogénèse d'une cellule surrénale de souris après transformation par l'adénovirus simien 7 (SA7).

After transformation by the simian adenovirus 7 (SA7), the Y-1 Mouse adrenal tumor cells are no longer able to produce steroïds either spontaneously, or after specific stimulation. Nevertheless, these stimulations are able to increase the level of cAMP both in transformed and original cell line. The differentiation is associated with an intracellular modification of steroïdogenesis which seems to be localized in the metabolic chain of steroïd synthesis after the increase of the cAMP level.

SV40 tumor rejection induced by vesicular stomatitis virus bearing SV40 tumor-specific transplantation antigen (SV40-TSTA). I. Specificity of immunoprotection and effect of enzyme treatment on TSTA activity.

Highly purified vesicular stomatitis virus (VSV) was obtained from VSV-infected SV40-transformed hamster cell lines. Immunization with this virus protected hamsters against challenge with SV40-transformed cells (TSV5-cl2). This protection was obtained regardless of the source of the SV40-transformed cells (e.g. cat, rat, hamster) used to produce VSV, and was therefore associated with the SV40 tumor-specific transplantation antigen (SV40-TSTA). Furthermore, when grown on spontaneously transformed cell lines or on cells transformed by a different oncogenic DNA virus, such as polyoma virus, the VSV failed to protect against the SV40-induced tumor. It was concluded that the SV40-TSTA activity of purified VSV is due to the incorporation of SV40-TSTA within the viral envelope. When VSV was treated with proteolytic enzymes (bromelain, trypsin) no loss of TSTA-induced tumor rejection was observed, although VSV had lost its ability to induce virus-neutralizing antibody. This clearly demonstrates that the TSTA activity is not related to the viral spikes. Phospholipase C suppressed the TSTA activity but neutralizing activity was still detectable in the anti-VSV sera. The results presented here demonstrate that the protection afforded by VSV is highly specific. It is particularly interesting that SV40-TSTA activity may be conveyed by the lipid core of the viral envelope.