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Synthesis and antidepressant activity of substituted (omega-aminoalkoxy)benzene derivatives.

A series of substituted (omega-aminoalkoxy)benzene derivatives has been synthesized and screened for potential antidepressant activities. The effect of structural variation of these molecules has been systematically examined. Antidepressant activity was clearly displayed by 2-benzyl-1-[4-(methylamino)butoxy]benzene (7), 2-(2-hydroxybenzyl)-1-[4-(methylamino)butoxy]benzene (19), 1-[4-(methylamino)butoxy]-2-phenoxybenzene (29), and 1-[4-(methylamino)butoxy]-2-(phenylthio)benzene (31) in further pharmacological studies. These compounds did not possess the anticholinergic, antihistaminic, and muscle-relaxant side effects common to tricyclic antidepressants.

Amino Alcohols↗

Cyclin-dependent protein kinases as therapeutic drug targets for antimalarial drug development.

Cyclin-dependent protein kinases (CDKs) have been attractive drug targets for the development of anticancer therapies due to their direct and crucial role in the regulation of cellular proliferation. Following this trend, CDKs have been pursued as potential drug targets for several other diseases. Structure-based drug design programmes have focused on the plasmodial CDKs to develop new candidate antimalarial compounds. This review discusses the most recent advances relating to three Plasmodium falciparum CDKs (PfPK5, PfPK6 and Pfmrk) as they are developed as antimalarial drug targets. CDKs are highly conserved, and focus must be placed upon the amino acid differences between human and plasmodial CDKs in order to develop specific inhibitors. Comparisons of the active sites of human and parasite CDKs reveal sequence and potential structural variations. Using sequence analysis, molecular modelling and in vitro drug screening, it is possible to identify and develop inhibitors that specifically target the plasmodial CDKs. These efforts are aimed at identifying new classes of CDK inhibitors that may be exploited for antimalarial drug development.

Amino Acid Sequence↗

Local differences in the trabecular bone structure of the proximal femur depicted with high-spatial-resolution MR imaging and multisection CT.

RATIONALE AND OBJECTIVES: The authors performed this study to investigate structural variations in the trabecular bone of the proximal femur at high-resolution magnetic resonance (MR) imaging and high-resolution multisection computed tomography (CT). MATERIALS AND METHODS: Bone mineral density (BMD) was measured in 36 proximal human femur specimens by using dual x-ray absorptiometry. High-resolution MR imaging was performed at 1.5 T with an in-plane spatial resolution of 0.195 x 0.195 mm and a section thickness of 0.3 and 0.9 mm. Multisection CT was performed with an ultra-high-resolution protocol; images were obtained with an in-plane spatial resolution of 0.25 mm and a section thickness of 1 mm. In a subset of these specimens, micro CT was performed with an isotropic spatial resolution of 30 microm. Identical regions of interest (ROIs) were used to analyze images obtained with MR imaging, multisection CT, and micro CT. Trabecular bone structural parameters were obtained, and the parameters from the individual imaging modalities and BMD were correlated. RESULTS: Significant differences concerning the trabecular microarchitecture between the individual ROIs were demonstrated with multisection CT and MR imaging. A number of the correlations between structural parameters derived with multisection CT, MR imaging, micro CT, and BMD measurements were significant. For MR imaging, threshold technique and section thickness had an effect on structural parameters. CONCLUSION: Structural parameters obtained in the proximal femur with multisection CT and high-resolution MR imaging show regional differences. These techniques may be useful for depicting the trabecular architecture in the diagnosis of osteoporosis.

Adult↗

Is scoliosis reversible? In Vivo observations of reversible morphological changes in the production of scoliosis in mice.

Without altering the osseous or muscular structure of Balb/c mice, the author was able to produce and reverse scoliotic deformation during the period of growth and development. Two series of investigations were performed, each involving extensive histological, morphological, and roentgenographic documentation: (1) control mice were maintained and sacrificed for examination at designated intervals and (2) experimental mice, whose right hind- and forequarters were surgically bound to allow only unilateral motion, were sacrificed and examined at corresponding intervals. The unilateral restriction of experimental animals were released at scheduled 5-day intervals during the 45-day period. These mice were then examined for restoration of normal histological and roentgenographic appearance. Changes in vertebral morphology were apparent after 35 days of restriction. Release at this time allowed restoration of normal vetebral appearance with the exception of a slight, measurable reduction in size. The results indicate that (1) limited activity retarded growth and (2) unilateral restriction caused geometrical variations (structural and morphological). Both of these alterations proved reversible once normal function (reciprocal motion) was restored to the murine spine.

Animals↗

A nuclease hypersensitive element in the human c-myc promoter adopts several distinct i-tetraplex structures.

Nucleic acid structure-function correlations are pivotal to major biological events like transcription, replication, and recombination. Depending on intracellular conditions in vivo and buffer composition in vitro, DNA appears capable of inexhaustible structure variation. At moderately acidic, or even neutral pH, DNA strands that are rich in cytosine bases can associate both inter- and intramolecularly to form i-tetraplexes. The hemiprotonated cytosine(+)-cytosine base pair constitutes the building block for the formation of i-tetraplexes, and motifs for their formation are frequent in vertebrate genomes. A major control element upstream of the human c-myc gene, which has been shown to interact sequence specifically with several transcription factors, becomes hypersensitive to nucleases upon c-myc expression. The control element is asymmetric inasmuch as that one strand is uncommonly rich in cytosines and exhibits multiple motifs for the formation of i-tetraplexes. To investigate the propensity for their formation we employ circular dichroism (CD) in combination with ultra violet (UV) spectroscopy and native gel electrophoresis. Our results demonstrate the cooperative formation of well-defined i-tetraplex structures. We conclude that i-tetraplex formation occurs in the promoter region of the human c-myc gene in vitro, and discuss implications of possible biological roles for i-tetraplex structures in vivo. Hypothetical formation of intramolecular fold-back i-tetraplexes is important to c-myc transcription, whereas chromosomal translocation events might involve the formation of bimolecular i-tetraplex structures.

Alleles↗

Delta-sleep-inducing peptide: solution conformational studies of a membrane-permeable peptide.

Peptides and peptide-like molecules as a class have very poor permeability through biological membranes, which severely compromises their potential effectiveness as therapeutic agents. In order to gain insight into the problem of delivering peptide and protein drugs and to establish a model in which the effects of systematic structural variations on transport can be explored, an investigation of the solution conformation of a membrane-permeable peptide was undertaken. Delta-sleep-inducing peptide (DSIP, MW 849) was used in this investigation. DSIP is a charged, hydrophilic peptide that possesses the unusual ability to diffuse passively across the blood-brain barrier (BBB) in vivo [Kastin, A. J., Banks, W. A., Castellanos, P. F., Nissen, C., & Coy, D. H. (1982) Pharmacol. Biochem. Behav. 17, 1187-1191] and across monolayers of brain microvessel endothelial cells in vitro, a model of the BBB [Raeissi, S., & Audus, K. L. (1989) J. Pharm. Pharmacol. 41, 848-852]. This nonapeptide was studied in solution using one- and two-dimensional nuclear magnetic resonance (NMR), circular dichroism (CD), Fourier transform infrared (FT-IR), and fluorescence spectroscopies in conjunction with molecular modeling. Our spectroscopic findings suggest that DSIP exists in a dynamic equilibrium between unordered and folded structures. Residues 2-5 and 6-9 tend to form type I beta-turns in aqueous solution and a similar, but more ordered, helix-like structure inducible in 40% trifluoroethanol (TFE). NMR, FT-IR, and CD studies in aqueous solution support the dynamic equilibrium hypothesis with the IR data, suggesting that the beta-turn population is approximately 40%.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

Modeling the role of nonhuman vocal membranes in phonation.

Although the mammalian larynx exhibits little structural variation compared to sound-producing organs in other taxa (birds or insects), there are some morphological features which could lead to significant differences in acoustic functioning, such as air sacs and vocal membranes. The vocal membrane (or "vocal lip") is a thin upward extension of the vocal fold that is present in many bat and primate species. The vocal membrane was modeled as an additional geometrical element in a two-mass model of the larynx. It was found that vocal membranes of an optimal angle and length can substantially lower the subglottal pressure at which phonation is supported, thus increasing vocal efficiency, and that this effect is most pronounced at high frequencies. The implications of this finding are discussed for animals such as bats and primates which are able to produce loud, high-pitched calls. Modeling efforts such as this provide guidance for future empirical investigations of vocal membrane structure and function, can provide insight into the mechanisms of animal communication, and could potentially lead to better understanding of human clinical disorders such as sulcus vocalis.

Humans↗

Bioreducible mustards: a paradigm for hypoxia-selective prodrugs of diffusible cytotoxins (HPDCs).

Existing hypoxia-selective cytotoxins (HSCs) are designed to kill only the hypoxic subpopulation in tumours, and to be used in conjunction with other therapies (e.g., radiation). A new class of drugs, hypoxia-activated prodrugs of diffusible cytotoxins (HPDCs) are proposed. These are designed to exploit, rather than merely deal with, tumour hypoxia, by releasing diffusible cytotoxins on bioreduction in hypoxic regions. Such diffusible cytotoxins are required to be much more cytotoxic than the parent prodrug, to be sufficiently stable (half lives from 0.1 to 10 min) to allow them to diffuse up to 200 microns from the hypoxic regions, and to be equally effective against all major tumour cell subpopulations, including non-cycling cells. Nitrogen mustards, which show little cell cycle specificity, which kill cells by a well-understood mechanism (DNA cross-links), and which have stabilities and reactivities able to be predictably controlled by structural variations, are proposed as suitable candidates fur such diffusible cytotoxins. Design parameters for two classes of potential HPDCs are discussed; nitro-deactivated aromatic mustards, and cobalt (III) complex-deactivated aliphatic mustards. Examples of both classes show greater cell-killing activity against intact compared with dissociated multi-cellular spheroids. This suggests they may indeed function as HPDCs, by penetrating to the hypoxic core of the spheroid and there releasing potent cytotoxins which diffuse out to kill surrounding cells at lower oxygen tensions.

Animals↗

Structural and functional aspects of the multiplicity of Neu differentiation factors.

We used molecular cloning and functional analyses to extend the family of Neu differentiation factors (NDFs) and to explore the biochemical activity of different NDF isoforms. Exhaustive cloning revealed the existence of six distinct fibroblastic pro-NDFs, whose basic transmembrane structure includes an immunoglobulin-like motif and an epidermal growth factor (EGF)-like domain. Structural variation is confined to three domains: the C-terminal portion of the EGF-like domain (isoforms alpha and beta), the adjacent juxtamembrane stretch (isoforms 1 to 4), and the variable-length cytoplasmic domain (isoforms a, b, and c). Only certain combinations of the variable domains exist, and they display partial tissue specificity in their expression: pro-NDF-alpha 2 is the predominant form in mesenchymal cells, whereas pro-NDF-beta 1 is the major neuronal isoform. Only the transmembrane isoforms were glycosylated and secreted as biologically active 44-kDa glycoproteins, implying that the transmembrane domain functions as an internal signal peptide. Extensive glycosylation precedes proteolytic cleavage of pro-NDF but has no effect on receptor binding. By contrast, the EGF-like domain fully retains receptor binding activity when expressed separately, but its beta-type C terminus displays higher affinity than alpha-type NDFs. Likewise, structural heterogeneity of the cytoplasmic tails may determine isoform-specific rate of pro-NDF processing. Taken together, these results suggest that different NDF isoforms are generated by alternative splicing and perform distinct tissue-specific functions.

Amino Acid Sequence↗

Analysis of the diversity of murine antibodies to dextran B1355. III. Idiotypic and spectrotypic correlations.

Examination of 19 S and 7 S anti-alpha(1 leads to 3) dextran (Dex) antibodies by serological assays and isoelectric focusing (IEF) has revealed substantial variation of idiotypic and spectrotypic expression between individuals of the same genotype. 7 S antibodies appeared to be more heterogeneous than 19 S by both methods. A strong, but complex, association was found between the IEF patterns of 19 S and 7 S anti-Dex antibodies and their expression of the idiotypic determinant(s) common to both the M104 and J558 dextran-binding myeloma proteins. However, no such relationship was found between the IEF pattern and the expression of idiotypic determinant(s) unique to the M104 myeloma protein. Rather, indistinguishable spectrotypes from different individuals have widely differing levels of expression of the determinant. In addition, this determinant(s) may be present on different spectrotypes of the same isotype. Both the M104 and J558-specific idiotypes were found on antibodies of the IgG3 subclass as well as in pools containing predominantly the IgG2a subclass. These data confirm and extend the picture of substantial structural variation among the antibodies comprising a response of restricted heterogeneity.

Animals↗

A method of studying adaptive changes of the oropharynx to variation in mandibular position in patients with obstructive sleep apnoea.

The aim of this study was to develop a method of studying the effects of mandibular advancement on oropharyngeal airway dimensions in the sagittal plane in conscious, supine patients. Six white, dentate, male patients with proven obstructive sleep apnoea had sagittal fluoroscopic recordings taken in the resting supine position. Images were recorded at four frames per second as the mandible was advanced with the teeth in contact to maximum protrusion and then opened. Software in the fluoroscopic imaging system permitted measurement of the change in mandibular position together with oropharyngeal airway dimensions expressed as the narrowest dimension observable in the post-palatal and post-lingual sites. Plotting of airway dimensions during mandibular advancement enabled estimation of the degree of protrusion associated with maximal airway benefits. Progressive mandibular advancement produced variable adaptive changes in the post-palatal and post-lingual regions of the oropharynx. The amount of airway opening appeared to be related to the horizontal and vertical relationships of the face and to the dimensions of the soft palate. The changes in post-palatal and post-lingual airway dimensions were not always identical, despite the observation that both tongue and soft palate were seen to move in unison, with close contact being maintained between the two structures. Jaw opening resulted in synchronous posterior movement of both tongue and soft palate, with consequent narrowing of oropharyngeal airspace. Fluoroscopy is a simple method of assessing upper airway changes with mandibular advancement in the conscious patient. The technique should facilitate the selection of subjects for whom mandibular advancement would seem advantageous. The nature of the adaptive response is dependent on individual structural variation. It is suggested that, where artificial mandibular advancement with dental devices is considered beneficial, jaw opening should be kept to a minimum.

Adaptation, Physiological↗

Temperature and salts effects on the peptidase activities of the recombinant metallooligopeptidases neurolysin and thimet oligopeptidase.

We report the recombinant neurolysin and thimet oligopeptidase (TOP) hydrolytic activities towards internally quenched fluorescent peptides derived from the peptide Abz-GGFLRRXQ-EDDnp (Abz, ortho-aminobenzoicacid; EDDnp, N-(2,4-dinitrophenyl) ethylenediamine), in which X was substituted by 11 different natural amino acids. Neurolysin hydrolyzed these peptides at R-R or at R-X bonds, and TOP hydrolyzed at R-R or L-R bonds, showing a preference to cleave at three or four amino acids from the C-terminal end. The kinetic parameters of hydrolysis and the variations of the cleavage sites were evaluated under different conditions of temperature and salt concentration. The relative amount of cleavage varied with the nature of the substitution at the X position as well as with temperature and NaCl concentration. TOP was activated by all assayed salts in the range 0.05-0.2 m for NaCl, KCl, NH4Cl and NaI, and 0.025-0.1 m for Na2SO4. Concentration higher than 0.2 N NH4Cl and NaI reduced TOP activity, while 0.5 N or higher concentration of NaCl, KCl and Na2SO4 increased TOP activity. Neurolysin was strongly activated by NaCl, KCl and Na2SO4, while NH4Cl and NaI have very modest effect. High positive values of enthalpy (DeltaH*) and entropy (DeltaS*) of activation were found together with an unusual temperature dependence upon the hydrolysis of the substrates. The effects of low temperature and high NaCl concentration on the hydrolytic activities of neurolysin and TOP do not seem to be a consequence of large secondary structure variation of the proteins, as indicated by the far-UV CD spectra. However, the modulation of the activities of the two oligopeptidases could be related to variations of conformation, in limited regions of the peptidases, enough to modify their activities.

Amino Acids↗

Novel pyrimidine and 1,3,5-triazine hypolipidemic agents.

New compounds were synthesized by changing the substituents of a trisubstituted pyrimidine, i.e., [[4-chloro-6-[(2,3-dimethylphenyl)amino]-2-pyrimidinyl]thio] acetic acid, a potent hypolipidemic agent, impaired, however, by a marked hepatomegaly-inducing effect. The structural variations led to the subsidence (14b, i.e., 4-chloro-2-(dimethylamino)-6-[(2,3-dimethylphenyl)amino]pyrimidine) or to the reduction (18b, [[4-chloro-6-[(2,3-dimethylphenyl)amino]-2-pyrimidinyl]amino] acetic acid) of said untoward effect but still maintained the hypolipidemic effect that, although markedly decreased, still proves significant for serum cholesterol and triglycerides (18b) or for serum triglycerides only (14b).

Animals↗

Synthesis of new macrocyclic chiral manganese(III) Schiff bases as catalysts for asymmetric epoxidation.

We describe a general synthetic strategy for the preparation of a series of macrocyclic chiral manganese(III) salen complexes. The developed reaction pathway allows the modulation of the different key groups, namely, the chiral diimine, the bulky substituents in positions 3 and 3', and the linker used in the macrocyclization of the Schiff base. The different complexes presented here illustrate these readily available structural variations. The catalytic properties of the catalysts (5 mol %) were improved for the asymmetric epoxidation of 2,2'-dimethylchromene with NaOCl or H2O2 as oxygen atom donor. A large range of enantiomeric excesses was obtained (ee values from 30% to 96%), depending on the features and the stability of the complexes. The most efficient catalyst, in terms of stereoinduction (ee value = 96%), contains a diiminocyclohexyl moiety, ethyl groups in positions 3 and 3', and a short polyether junction arm.

Catalysis↗

Structural studies on the core and lipid A region of a 4-amino-L-arabinose-lacking Rc-type mutant of Proteus mirabilis.

The structure of the 4-amino-L-arabinose-lacking lipopolysaccharide of the Proteus mirabilis Rc-type mutant R4, derived from wild-type O28, was elucidated. The lipopolysaccharide core structure has previously been partially characterized. The linkage between heptose and deoxyoctulosonic acid(dOclA) is now reported, as well as the structure of the lipid A moiety of this mutant strain. Besides the tentative identification of an alpha-linked glucosamine disaccharide in the lipid A backbone accompanying the usual beta 1----6-linked glucosamine-disaccharide, the only significant structural variation to previous studies was the lack of substitution of the C-4' phosphate by 4-amino-L-arabinose. In addition, the substitution at C-8 of one dOclA unit by 4-amino-L-arabinose, previously reported for the R45 mutant of P. mirabilis 1959, is lacking in this R mutant. Also in addition to previous findings, the terminal unit of heptose was found to be substituted at C-7 with phosphorylethanolamine (PEtN) and not only with phosphate, although this substitution is not complete as demonstrated by the relevant signals in 31P-NMR. Additional studies with the wild-type strain P. mirabilis O28 revealed the presence of 4-amino-L-arabinose in both the core and the lipid A regions suggesting that the R4 mutant is defective in the biosynthesis of this amino sugar rather than in its transfer. Otherwise the lipid A regions of the mutant and the wild-type strain show no structural differences. The following formula is proposed for the lipopolysaccharide of 4-amino-L-arabinose-lacking mutant R4/O28 P. mirabilis: (Formula; see text)

Electrophoresis, Polyacrylamide Gel↗

Synthesis and pharmacological study of Rho-kinase inhibitors: pharmacomodulations on the lead compound Fasudil.

With a view to specifying structure-activity relationships we have synthesised a new series of analogues of the Rho-kinase inhibitor 1-(5-isoquinolinesulfonyl)-homopiperazine (Fasudil). The structural modifications concerned the isoquinolinyl heterocycle and the sulfonyl group which are the two main features of this lead compound. These analogues were evaluated on the actin cytoskeleton and on the enzymatic activity of Rho-kinase. Most of the chemical modifications result in a loss of activity showing that interactions of Fasudil with the catalytic domain of Rho-kinase seem to be particularly definite and sensitive to structural variations. The presence of an isoquinolinyl nitrogen and a basic amino group separated by a spacer bearing a sulfonamide function are of utmost importance. Only the tetra-hydroisoquinoline analogue 3 shows the same activity as Fasudil. Moreover, this compound is unable to inhibit PKC biological activity contrary to Fasudil. The loss of the aromatic property could increase the selectivity level in favour of compound 3.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Structurally interdependent and independent regions of allelic polymorphism in class II MHC molecules. Implications for Ia function and evolution.

Possible interactions between regions of allelic polymorphism in the alpha- and beta-chains of class II MHC molecules were examined by measuring the efficiency of surface expression and the reactivity with mAb of wild-type and recombinant A alpha A beta-chain pairs from the b, d, and k haplotypes. These studies revealed regions of polymorphism within the alpha- and beta-chains that interact with complementary regions in the other chain. Unexpectedly, almost all the variable segments of both the class II MHC alpha- and beta-chains either directly contributed to or were near sites of interchain interactions. The exception was the beta HV3 (hypervariable (HV] segment (residues 61-71), which appeared to neither participate in nor be affected by interchain interactions. This division of the MHC molecule into interacting vs independent regions of allelic structural variation suggests that mutagenesis experiments involving the beta HV3 segment can be analyzed in a straightforward manner, as such mutations appear unlikely to alter the conformation of other molecular segments. Furthermore, functions attributed to the beta HV3 segment either experimentally or by population analysis should have a high probability of transfer by beta HV3 exchange (either experimentally or evolutionarily), because epitopes assigned to this region of the molecule are not affected by sequences outside this segment. This is of special importance because of the apparent involvement of this region in defining a potential site of interaction with antigenic peptides and TCR. In contrast, almost all other variable segments of the MHC molecule appear to have the capacity to contribute to interactions involving at least one other variable segment. This suggests not only that the experimental analysis of the contributions of these regions to various functions requires a consideration of inter- and intrachain interaction, but also that the transfer of function by genetic exchange of these structurally dependent regions is unpredictable. Selection must therefore operate on these interacting HV segments in the context of the complete alpha beta heterodimer. These results support our earlier arguments for cis-co-evolution of alpha- and beta-chain polymorphism and the absence of selection for F1 (hybrid) class II molecules. Finally, asymmetries observed in the contributions of particular pairs of HV segments to the efficient expression of Ia alpha beta heterodimers provide a basis for understanding mechanistically how cis-co-evolution may have occurred.

Alleles↗

STK11 Mutations and Deletions Define an Aggressive Molecular Subgroup of Cervical Adenocarcinoma.

Cervical adenocarcinoma accounts for 15%-20% of cervical cancers and is associated with poorer survival and reduced response to screening and immunotherapy compared with squamous cell carcinoma (SCC). The genomic drivers underlying this molecular subgroup remain incompletely characterized. Whole-exome sequencing was performed on 302 invasive cervical cancers from Guatemala and Venezuela. Structural variation analysis was conducted using SNP-array and whole-genome sequencing data. Findings were replicated in more than 4600 additional cervical cancer samples from TCGA, AACR Project GENIE, MSKCC, and Caris datasets. TP53 mutations were more frequent in adenocarcinoma than SCC, particularly in HPV-negative tumors. STK11 alterations, including mutations and focal deletions, were significantly enriched in HPV-positive adenocarcinomas compared with SCC and affected 23% of adenocarcinomas overall. Whole-genome analyses identified recurrent focal deletions, inversions, chromosomal rearrangements, and breakage-fusion-bridge events involving chromosome 19p and STK11 that were not detected by exome sequencing alone. STK11 alterations were associated with younger age at diagnosis, poorer overall survival, and inferior outcomes following immune checkpoint inhibitor (ICI) therapy. STK11 alterations significantly co-occurred with YAP1 amplification but were largely mutually exclusive with PIK3CA mutation. Cervical adenocarcinomas also demonstrated significantly lower CD274 (PD-L1) expression than SCC. STK11 alterations define a distinct molecular subgroup of cervical adenocarcinoma characterized by structural disruption of chromosome 19p, younger age at onset, and poorer clinical outcomes. These findings have implications for molecular classification and future targeted therapeutic approaches in cervical cancer.

Humans↗