Poor Biological Activity Research Articles

IgE to Cross-Reactive Carbohydrate Determinants: Analysis of the Distribution and Appraisal of the in vivo and in vitro Reactivity

Background: IgE to cross-reacting carbohydrate determinants has already been described by several authors, but their function and distribution are still a matter of debate. In previous studies we showed how the presence of IgE to bromelain could be a useful and simple marker of the presence of IgE to carbohydrate epitopes. Methods: A survey of 1,831 subjects with a suspected allergic respiratory disease has been carried out by detecting IgE to bromelain. Data were analysed on the basis of demographical and allergological parameters. To find out whether a glycoprotein is capable of triggering an allergic reaction, 1,076 subjects were also skin tested with several purified molecules bearing carbohydrate side chains differing in number, composition and complexity. Results: An overall prevalence of 23% of positive IgE to cross-reacting carbohydrate determinants was recorded. Prevalence varied when subsets of non-allergic (5%), non-pollen-allergic (10%), and pollen-allergic (31%) subjects were considered. Prevalence further increased in subsets with multiple pollen sensitization (71%), and with a previous pollen immunotherapy course (46%), whereas minor differences were found in gender and age distribution. Almost all the allergenic extracts recorded negative in the skin test gave a positive IgE test in vitro. A higher correlation was found mainly with plant-derived allergenic extracts, whereas a lower one was recorded with mites and fungi. Horseradish peroxidase was the only glycoprotein capable of exerting a positive skin test in 21% of the subjects with IgE to cross-reacting carbohydrate determinants, 80% of them having IgE to the HRP molecule. Conclusions: IgE to cross-reacting carbohydrate determinants are common among the allergic population and the binding to skin test negative allergenic extracts further confirms their poor biological activity. Further studies on horseradish peroxidase should be carried out to define the role of the glycan side chains in its allergenic activity.

Poor biological activity of cross-reactive IgE directed to carbohydrate determinants of glycoproteins

Poor biological activity of cross-reactive IgE directed to carbohydrate determinants of glycoproteins

Poor biological activity of cross-reactive IgE directed to carbohydrate determinants of glycoproteins

Poor biological activity of cross-reactive IgE directed to carbohydrate determinants of glycoproteins

Conformational study of somatostatin analogues in methanol at low temperature

AbstractThe conformations of three somatostatin analogues were compared in methanol at 193 K. A biologically active cyclic analogue, DC13‐116 (D‐Nal5‐Cys6‐Tyr7‐D‐Trp8‐Lys9‐Val10‐Cys11‐Thr12‐NH2), and two linear analogues, one biologically active, DC25‐24 (D‐Phes5‐Cpa6‐Tyr7‐D‐Trp8‐Lys 9‐Val10‐Phe11‐Thr12‐NH2), and one with poor biological activity, DC23‐89 (D‐Phe5‐Ala6‐Phe7‐D‐Trp8‐Lys9‐Thr10‐Ala11‐Thr12‐NH2), were compared. The predominant conformation of the linear active analogue is shown to be the same as that of the active cyclic analogue; they both adopt a β11 turn/β‐sheet structure. The linear analogue with low activity has a similar conformation, which, however, is less stable.

Diethylstilbestrol Metabolites and Analogs: Stereochemical probes for the estrogen receptor binding site

Indenestrol A (IA) and indenestrol B (IB) are analogs and metabolites of diethylstilbestrol (DES). These compounds have high binding affinity with the estrogen receptor (ER) but possess weak uterotropic activity. Due to their chemical structures, IA and IB exist as mixtures of enantiomers. We investigated whether the poor biological activity of these compounds was due to differential activity of the enantiomers. We also utilized these compounds as probes to determine the extent of stereochemical sensitivity in the ER ligand binding site. The IA and IB enantiomers were separated to greater than 98% purity using a chiral high pressure liquid chromatography column. Their enantiomeric nature was confirmed by mass spectrometry and NMR. The purified IA enantiomer peak 1 was derivatized with 4-bromobenzoyl chloride. The resulting di(4-bronobenzoate) IA was analyzed by x-ray crystallography and the absolute enantiomeric conformation assigned is C(3)-R. The IA enantiomers designated IA-R and A-S were assayed by competitive binding to cytosolic ER. The competitive binding index was estradiol, 100; DES, 286; IA-Rac (racemic mixture of IA), 143; IA-R, 3; and IA-S, 285; the index showed that ER demonstrates a stereochemical chiral preference. The IB enantiomers did not show a binding preference: IB, 145; IB-1, 100; and IB-2, 143. The differences in the IA enantiomer binding were shown to be due to competitive interactions by Lineweaver-Burk analysis of saturation binding of estradiol to ER in the presence of 1-, 5-, and 10-fold molar excess of competitor. Differences in binding affinity of the enantiomers could be partially explained by differences in the association rate constant (k+1) determined by association rate inhibition studies in which IA-S was 15 times more active than IA-R. Nuclear estrogen receptor levels were measured 1 h after in vivo treatment with doses of 5-20 micrograms/kg. The IA-Rac produced only 60% of the levels is compared with DES. Nuclear ER levels were checked every 30 min up to 2 h with no apparent difference, indicating that the low early levels were not due to a delayed estrogen receptor retention. When the enantiomers were tested individually only a dose of 10 micrograms/kg IA-S translocated ER to a level comparable to DES, while IA-R showed low levels at several doses. These results suggest that the poor biological activity of IA may be related to the differential ER interaction of its enantiomers.(ABSTRACT TRUNCATED AT 400 WORDS)

Estrogen receptor stereochemistry: Receptor binding and hormonal responses

Estrogen stimulation of the uterus elicits a spectrum of biochemical responses which are customarily linked together. DES and certain structural analogs, indenestrol A (IA), indenestrol B (IB), indanestrol (I), and pseudo DES (PD), were used as probes to segregate various genomic responses previously considered interrelated, most notably the events of specific protein synthesis, DNA synthesis, and mitosis. These compounds have poor uterotrophic activity; except for I, they interact specifically with mouse uterine estrogen receptors (ER) with high affinity. All translocate stoichiometrically similar amounts of ER complex to the nucleus. IA and IB possess a single chiral carbon atom and exist as a mixture of enantiomers (ENT). We investigated whether the poor biological activity of IA could be explained by differential activity of the enantiomers. The IA ENT were separated to > 98% purity using a chirally active HPLC column. Competitive binding assays to cytosolic ER demonstrated a stereochemical chiral preference. This preference was also evident from nuclear ER translocation experiments. IB was as active as DES to induce mouse uterine glucose 6-phosphate dehydrogenase (G-6-PD), while the other compounds had weak activity. Induction of cytosolic progesterone receptor (PR) was stimulated by all the DES compounds. Ornithine decarboxylase (ODC) was stimulated 600% by DES and 180% by IB; the other compounds had no significant activity. Uterine DNA synthesis was increased by DES and IB. Thymidine autoradiography indicated nuclear labeling was occurring primarily in luminal epithelium. Treatment with PD increased uterine cell height but not cell numbers, suggesting the two responses are not necessarily interdependent as previously thought and may require two separate receptor interactions. Such a probe should be useful in studying the individual events involved in estrogen-induced uterine growth. These data also indicate that induction of ER, PR and G-6-PD are not coupled. Therefore, stimulation of a certain uterine response may depend on the structure of the particular ligand receptor complex formed, and its interaction may be regulated by specificity at the genomic acceptor site.

Characterization of a Defective Mutant of the Dahlemense Strain of Tobacco Mosaic Virus

A mutant of tobacco mosaic virus has been isolated after treating the dahlemense strain with nitrous acid and called D 16y. Like dahlemense it produces necrotic lesions on java-type tobacco but induces a strong chlorosis on samsun tobacco, in which it spreads systemically. Yield of virus from infected plants is significantly lower than that of dahlemense and the virus particles are unstable in vitro, and probably also in vivo. It is serologically closely related to dahlemense, its coat protein is somewhat less electronegative in weakly alkaline medium and it is inactivated at elevated temperatures more easily than dahlemense. Its coat protein contains a histidine residue, that is not present in dahlemense. The poor biological activity and the instability of D 16y toward storage and high temperatures are properties that are common with many defective mutants. D 16y is possibly the first induced mutant of dahlemense and with its several altered characters is expected to be very useful for comparative studies on the structure and action of TMV.

46 ELEVATED SERUM THYROTROPIN (TSH) IN IDIOPATHIC HYPOPITUITARISM

Numerous reports have confirmed the occurrence of elevated serum TSH in idiopathic hypopituitarism, suggesting association with primary thyroid disease or production of an abnormal TSH. Eight hypopituitary children with high baseline TSH concentrations between 6.6 and 33uU/ml (Normal: X ± SD=2.30 ± 1.13) were evaluated. TSH response to TRH were exagerated, prolonged and/or delayed. Serum T4 were normal in 6/8 and low in 2. bTSH (Bovine TSH) stimulation showed increase above baseline values in T4 (range 81-158%) and T3 (range 135-340%) similar to the responses obtained in the control group (n=4, T4 = 64-183%, T3=59-441%). Antithyroid antibodies were negative in 7/8. Elevated TSH levels were suppressed following either thyroxine treatment in 2/2 patients and bTSH in 3/3. The normal T4 and T3 responsiveness to TSH stimulation and the suppression of elevated TSH suggest a normal response to thyroid gland and an intact feedback mechanism. Elevated TSH levels associated with normal or low T4 in the presence of a normally TSH responding thyroid gland suggests that the TSH detected in serum had poor biological activity.

Palynology and pollen preservation

Despite the fact that pollen analysis is very often applied to sediments with poorly preserved pollen, pollen and spore corrosion is a greatly neglected subject in palynological research. Lack of knowledge about susceptibility to decay of the individual pollen or spore species may easily lead to misinterpretation of pollen diagrams. Pollen corrosion is a very complex concept, comprising the effect of various external factors (microbial attack, oxidation, mechanical forces, high temperature) as well as factors inherent to the pollen grains or spores themselves (sporopollenine content, chemical and physical composition of the pollen or spore wall). A special study is needed for a proper appreciation of the influence of each of these factors. The author applied experimental laboratory and field research to twenty pollen and spore species. The study includes research on differential susceptibility to chemical oxidation and microbial attack in various soil types. Investigations were also begun on microbial attack under laboratory conditions. It was found that a parallel exists between differential susceptibility to oxidation and differential susceptibility to decay in a natural environment, insofar as the latter was established from written evidence. These data refer to soils with poor biological activity. Corrosion tests, however, showed that differential susceptibility to corrosion of several pollen species is quite different in soils rich in this respect. This is connected with the corrosion effect of the perforation type mainly found in this type of soil. An investigation of some fossil podsol profiles revealed the frequent occurrence of pollen with a perforated exine in one of them. The theory adduced is that the perforations mainly originate from a phase of soil formation, preceding the present profile, which had a rich biological activity. The soil podzolized rapidly and then submerged, so that the corrosion phenomena were “fossilized”.