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Background: Disability affects a significant portion of the global population nowadays, necessitating innovative approaches to access rehabilitation processes. Home-based rehabilitation has emerged as a beneficial approach, offering comfort and context-specific therapy., Objective: This study aims to evaluate the impact of a multidisciplinary home-based rehabilitation program for individuals with moderate neuromusculoskeletal disabilities in terms of motor function and mood., Methods: A total of 270 participants with median age of 66 (IQR 20-98) years were recruited from the National Disability Registry of Chile. The intervention involved a multidisciplinary team composed of 49 health care professionals providing personalized treatment plans over 4 months (32 sessions for physical therapy, 8 sessions for occupational therapy, 4 sessions for nutrition, 8 sessions for psychology, and 4 sessions for nursing and podiatry). This program also included 2 medical evaluations (at the beginning and the end) to monitor clinical progress in terms of motor function and mental health, using the Berg Balance Scale and Beck Depression Inventory, respectively., Results: The home-based rehabilitation program showed significant improvements (P<.001) in motor function and balance with a reduction in fall risk. Specifically, the Berg Balance Scale score decreased close to 15% after the home-based rehabilitation program for all enrolled participants. On the other hand, depression levels showed no significant changes (P=.27), with percentages of variation less than 8% between the 2 assessed conditions. In this sense, participants remained with the same mild depression level (14 of 63) concerning the Beck Depression Inventory score., Conclusions: This study concludes that personalized home-based rehabilitation programs are effective in enhancing motor function and balance, particularly in individuals with neurological conditions. On the other hand, the findings in terms of mood advocate for further exploration of psychological support within such programs to enhance overall patient well-being., Trial Registration: ClinicalTrials.gov NCT06537791; https://clinicaltrials.gov/study/NCT06537791., (©Patricio Barría, Asterio Andrade, Daniel Gomez-Vargas, Alejandro Yelincic, Flavio Roberti, Eduardo Bahamonde, Rolando Aguilar, Bessie Cordova. Originally published in JMIR Rehabilitation and Assistive Technology (https://rehab.jmir.org), 16.10.2024.)

Understanding the differences in ventilatory responses during exercise between patients with fibromyalgia and those with other chronic pain disorders is crucial for developing effective therapeutic interventions, especially in exercise to identify the better physical therapy prescription. Both populations face unique challenges that impact their ability to engage in physical activity; yet, the underlying physiological responses can vary significantly. In this context, the methodology of this study entailed conducting a comparative analysis of the ventilatory response during exercise in patients with fibromyalgia and those with other chronic pain disorders. The experimental protocol included a total of 31 participants (n = 13 diagnosed with fibromyalgia and n = 18 diagnosed with other chronic pain conditions). All participants completed a stress test, where the ventilatory parameters were measured in three stages (i.e., resting, incremental exercise, and recovery). The results revealed significant differences (p<0.05) in ventilatory responses between both groups. Patients with fibromyalgia exhibited reduced time for the aerobic threshold and a higher respiratory frequency in the anaerobic threshold compared to those with other chronic pain disorders. Furthermore, fibromyalgia patients demonstrated higher values in the ventilatory coefficient during the test and in the recovery stage. In conclusion, these differences underscore the need for tailored exercise programs that specifically address the unique ventilatory challenges faced by fibromyalgia patients to improve their physical function and overall quality of life.

Growing resistance to current antiparasitic medications, both in livestock and in zoological species under human care, makes it imperative to evaluate available drugs on the market, such as eprinomectin. In this prospective study, five males and one female of reticulated ( Giraffa reticulata ; n = 2), Masai ( Giraffa tippelskirchii ; n = 1), Nubian ( Giraffa camelopardalis ; n = 2), and hybrid subspecies ( n = 1) of giraffe, received 1.5 mg/kg eprinomectin topically along the dorsum. Using high-performance liquid chromatography, concentrations of eprinomectin in plasma samples collected at 0, 4, 24, and 48 h, and 7, 14, 21, and 28 d were evaluated following drug administration. Complete blood cell counts and biochemistry panels were performed before ( n = 6) and after ( n = 3) eprinomectin administration. Samples for modified double centrifugal fecal flotation ( n = 6) were evaluated prior to eprinomectin administration to evaluate for endoparasites and were repeated after the study ( n = 5). Noncompartmental pharmacokinetic analysis was applied to the data. The observed maximum plasma concentration was 11.45 ng/ml and the time of observed maximum concentration was 2.67 d. The mean terminal half-life was 5.16 d. No adverse effects were observed related to eprinomectin administration and no blood work changes were observed. Parasite loads decreased ( n = 3) or did not change ( n = 2) after eprinomectin administration. The mean peak plasma concentration of eprinomectin in giraffe was similar to that achieved in cattle, despite using three times the dose.

Shotgun metagenomics applied to archaeological feces (paleofeces) can bring new insights into the composition and functions of human and animal gut microbiota from the past. However, paleofeces often undergo physical distortions in archaeological sediments, making their source species difficult to identify on the basis of fecal morphology or microscopic features alone. Here we present a reproducible and scalable pipeline using both host and microbial DNA to infer the host source of fecal material. We apply this pipeline to newly sequenced archaeological specimens and show that we are able to distinguish morphologically similar human and canine paleofeces, as well as non-fecal sediments, from a range of archaeological contexts., Competing Interests: The authors declare that they have no competing interests., (© 2020 Borry et al.)

Amblypygids use a pair of modified walking legs (antenniform) as chemosensory and mechanosensory appendages. At the tip of these legs are covered in chemosensory sensilla, which the animals use to sample odor stimuli in their environment by moving the antenniform leg through the air. We designed a set of experiments to measure the filtering effect that aerodynamic boundary layers have on the temporal and spatial structure of chemical stimuli. In addition, two different species of amblypygids (Paraphrynus laevifrons and Phrynus marginemaculatus) that live in two distinct habitats were used for a comparative analysis. Pulses of a tracer molecule were quantified at different distances and flow velocities using an electrochemical detection system. Temporal attributes of the chemical pulses were extracted and were statistically compared across velocities, distances from the appendage, and the two species. Overall, the boundary layer significantly decreased the concentration and increased the duration of pulses for both species. This filtering effect was more pronounced for P. marginemaculatus than P. laevifrons, as the chemical signal was lower in concentration and longer in duration at any distance from the antenniform leg. It is speculated that the difference in boundary layer filtering, as a function of appendage morphology, is tuned to the different types of odor plumes in these animals' native habitats., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Thiamine biosynthesis is commonly regulated by a riboswitch mechanism; however, the enzymatic steps and regulation of this pathway in archaea are poorly understood. Haloferax volcanii , one of the representative archaea, uses a eukaryote-like Thi4 (thiamine thiazole synthase) for the production of the thiazole ring and condenses this ring with a pyrimidine moiety synthesized by an apparent bacterium-like ThiC (2-methyl-4-amino-5-hydroxymethylpyrimidine [HMP] phosphate synthase) branch. Here we found that archaeal Thi4 and ThiC were encoded by leaderless transcripts, ruling out a riboswitch mechanism. Instead, a novel ThiR transcription factor that harbored an N-terminal helix-turn-helix (HTH) DNA binding domain and C-terminal ThiN (TMP synthase) domain was identified. In the presence of thiamine, ThiR was found to repress the expression of thi4 and thiC by a DNA operator sequence that was conserved across archaeal phyla. Despite having a ThiN domain, ThiR was found to be catalytically inactive in compensating for the loss of ThiE (TMP synthase) function. In contrast, bifunctional ThiDN, in which the ThiN domain is fused to an N-terminal ThiD (HMP/HMP phosphate [HMP-P] kinase) domain, was found to be interchangeable for ThiE function and, thus, active in thiamine biosynthesis. A conserved Met residue of an extended α-helix near the active-site His of the ThiN domain was found to be important for ThiDN catalytic activity, whereas the corresponding Met residue was absent and the α-helix was shorter in ThiR homologs. Thus, we provide new insight into residues that distinguish catalytic from noncatalytic ThiN domains and reveal that thiamine biosynthesis in archaea is regulated by a transcriptional repressor, ThiR, and not by a riboswitch. IMPORTANCE Thiamine pyrophosphate (TPP) is a cofactor needed for the enzymatic activity of many cellular processes, including central metabolism. In archaea, thiamine biosynthesis is an apparent chimera of eukaryote- and bacterium-type pathways that is not well defined at the level of enzymatic steps or regulatory mechanisms. Here we find that ThiN is a versatile domain of transcriptional repressors and catalytic enzymes of thiamine biosynthesis in archaea. Our study provides new insight into residues that distinguish catalytic from noncatalytic ThiN domains and reveals that archaeal thiamine biosynthesis is regulated by a ThiN domain transcriptional repressor, ThiR, and not by a riboswitch., (Copyright © 2017 American Society for Microbiology.)

Background: Thiamine (vitamin B1) is synthesized de novo by certain yeast, fungi, plants, protozoans, bacteria and archaea. The pathway of thiamine biosynthesis by archaea is poorly understood, particularly the route of sulfur relay to form the thiazole ring. Archaea harbor structural homologs of both the bacterial (ThiS-ThiF) and eukaryotic (THI4) proteins that mobilize sulfur to thiazole ring precursors by distinct mechanisms., Results: Based on comparative genome analysis, halophilic archaea are predicted to synthesize the pyrimidine moiety of thiamine by the bacterial pathway, initially suggesting that also a bacterial ThiS-ThiF type mechanism for synthesis of the thiazole ring is used in which the sulfur carrier ThiS is first activated by ThiF-catalyzed adenylation. The only ThiF homolog of Haloferax volcanii (UbaA) was deleted but this had no effect on growth in the absence of thiamine. Usage of the eukaryotic THI4-type sulfur relay was initially considered less likely for thiamine biosynthesis in archaea, since the active-site cysteine residue of yeast THI4p that donates the sulfur to the thiazole ring by a suicide mechanism is replaced by a histidine residue in many archaeal THI4 homologs and these are described as D-ribose-1,5-bisphosphate isomerases. The THI4 homolog of the halophilic archaea, including Hfx. volcanii (HVO&#95;0665, HvThi4) was found to differ from that of methanogens and thermococci by having a cysteine residue (Cys165) corresponding to the conserved active site cysteine of yeast THI4p (Cys205). Deletion of HVO&#95;0665 generated a thiamine auxotroph that was trans-complemented by a wild-type copy of HVO&#95;0665, but not the modified gene encoding an HvThi4 C165A variant., Conclusions: Based on our results, we conclude that the archaeon Hfx. volcanii uses a yeast THI4-type mechanism for sulfur relay to form the thiazole ring of thiamine. We extend this finding to a relatively large group of archaea, including haloarchaea, ammonium oxidizing archaea, and some methanogen and Pyrococcus species, by observing that these organisms code for THI4 homologs that have a conserved active site cysteine residue which is likely used in thiamine biosynthesis. Thus, archaeal members of IPR002922 THI4 family that have a conserved cysteine active site should be reexamined for a function in thiamine biosynthesis.

Background: Silicon is the element most similar to carbon, and bioactive organosilanes have therefore been of longstanding interest. Design of bioactive organosilanes has often involved a systematic replacement of a bioactive molecule's stable carbon atoms with silicon. Silanediols, which are best known as unstable precursors of the robust and ubiquitous silicone polymers, have the potential to mimic an unstable carbon, the hydrated carbonyl. As a bioisostere of the tetrahedral intermediate of amide hydrolysis, a silanediol could act as a transition state analog inhibitor of protease enzymes., Results: Silanediol analogs of a carbinol-based inhibitor of the HIV protease were prepared as single enantiomers, with up to six stereogenic centers. As inhibitors of this aspartic protease, the silanediols were nearly equivalent to both their carbinol analogs and indinavir, a current treatment for AIDS, with low nanomolar K(i) values. IC(90) data from a cell culture assay mirrored the K(i) data, demonstrating that the silanediols can also cross cell membranes and deliver their antiviral effects., Conclusions: In their first evaluation as inhibitors of an aspartic protease, silanediol peptidomimetics have been found to be nearly as potent as currently available pharmaceutical agents, in enzyme and cell protection assays. These neutral, cell-permeable transition state analogs therefore provide a novel foundation for the design of therapeutic agents.

Human immunodeficiency virus (HIV) protease inhibitors (PIs) are important components of many highly active antiretroviral therapy regimens. However, development of phenotypic and/or genotypic resistance can occur, including cross-resistance to other PIs. Development of resistance takes place because trough levels of free drug are inadequate to suppress preexisting resistant mutant variants and/or to inhibit de novo-generated resistant mutant variants. There is thus a need for new PIs, which are more potent against mutant variants of HIV and show higher levels of free drug at the trough. We have optimized a series of substituted sulfonamides and evaluated the inhibitors against laboratory strains and clinical isolates of HIV type 1 (HIV-1), including viruses with mutations in the protease gene. In addition, serum protein binding was determined to estimate total drug requirements for 90% suppression of virus replication (plasma IC(90)). Two compounds resulting from our studies, designated DPC 681 and DPC 684, are potent and selective inhibitors of HIV protease with IC(90)s for wild-type HIV-1 of 4 to 40 nM. DPC 681 and DPC 684 showed no loss in potency toward recombinant mutant HIVs with the D30N mutation and a fivefold or smaller loss in potency toward mutant variants with three to five amino acid substitutions. A panel of chimeric viruses constructed from clinical samples from patients who failed PI-containing regimens and containing 5 to 11 mutations, including positions 10, 32, 46, 47, 50, 54, 63, 71, 82, 84, and 90 had mean IC(50) values of <20 nM for DPC 681 and DPC 681, respectively. In contrast, marketed PIs had mean IC(50) values ranging from 200 nM (amprenavir) to >900 nM (nelfinavir).

A series of 4,4-disubstituted quinolinones was prepared and evaluated as HIV-1 reverse transcriptase inhibitors. The C-3 substituted compound 9h displayed improved antiviral activity against clinically significant single (K103N) and double (K103N/L100I) mutant viruses.

A series of 4,1-benzoxazepinone analogues of efavirenz (Sustiva) as potent NNRTIs has been discovered. The cis-3-alkylbenzoxazepinones are more potent then the trans isomers and can be synthesized preferentially by a novel stereoselective cyclization. The best compounds are potent orally bioavailable inhibitors of both wild-type HIV-1 and its clinically relevant K103N mutant virus, but are highly protein-bound in human plasma.

Efavirenz (also known as DMP 266 or SUSTIVA) is a potent nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and of HIV-1 replication in vitro and in vivo. Most patients on efavirenz-containing regimens have sustained antiviral responses; however, rebounds in plasma viral load have been observed in some patients in association with the emergence of mutant strains of HIV-1. Virus isolates from the peripheral blood mononuclear cells (PBMCs) of patients with such treatment failures, as well as recombinant viruses incorporating viral sequences derived from patient plasma, show reduced in vitro susceptibility to efavirenz in association with mutations in the RT gene encoding K103N, Y188L, or G190S/E substitutions. Patterns of RT gene mutations and in vitro susceptibility were similar in plasma virus and in viruses isolated from PBMCs. Variant strains of HIV-1 constructed by site-directed mutagenesis confirmed the role of K103N, G190S, and Y188L substitutions in reduced susceptibility to efavirenz. Further, certain secondary mutations (V106I, V108I, Y181C, Y188H, P225H, and F227L) conferred little resistance to efavirenz as single mutations but enhanced the level of resistance of viruses carrying these mutations in combination with K103N or Y188L. Viruses with K103N or Y188L mutations, regardless of the initial selecting nonnucleoside RT inhibitor (NNRTI), exhibited cross-resistance to all of the presently available NNRTIs (efavirenz, nevirapine, and delavirdine). Some virus isolates from nevirapine or delavirdine treatment failures that lacked K103N or Y188L mutations remained susceptible to efavirenz in vitro, although the clinical significance of this finding is presently unclear.

Two series of efavirenz analogues have been developed: one in which the cyclopropane ring has been replaced by small heterocycles and another in which the entire acetylenic side chain has been replaced by alkyloxy groups. Several members of both series show equivalent potency to efavirenz against both wild-type virus and the key K103N mutant.

Studies on the biotransformation of the clinically important non-nucleoside reverse transcriptase inhibitor efavirenz have shown that oxidation and secondary conjugation are important components of the processing of this molecule in vivo. We have synthesized metabolites of efavirenz to confirm their structure and to evaluate their activity as antivirals.

3-Alkoxymethyl- and 3-aryloxymethyl-2-pyridinones were synthesized and evaluated for activity as non-nucleoside reverse transcriptase inhibitors (NNRTIs) of HIV-1. It was found that several compounds were potent inhibitors of HIV-1 with the most potent compound 24 exhibiting an IC90 = 32 nM. Compound 24 also possessed a potent resistance profile as demonstrated by submicromolar IC90s against several clinically meaningful mutant virus strains.

A series of unique 3,3a-dihydropyrano[4,3,2-de]quinazolin-2(1H)-ones and a 2a,5-dihydro-2H-thieno[4,3,2-de]quinazo-line-4(3H)-thione were found to be HIV-1 non-nucleoside reverse transcriptase inhibitors. One of these compounds, as the racemate, possessed an IC90 = 4.6 nM against wild-type virus in a whole cell antiviral assay and had an IC90 = 76 and 897 nM against the clinically significant K103N and K103N/L100I mutant viruses, respectively.

A series of 3,3-disubstituted quinoxalinones was prepared and evaluated as HIV-1 reverse transcriptase inhibitors. The N-allyl (6b and 6f), N-cyclopropylmethyl (6a, 6g, 6h, and 6k) and N-carboalkoxy (6m-6y) substituted compounds displayed activity comparable or better than Efavirenz and GW420867X.

A series of 4-alkenyl and 4-alkynyl-3, 4-dihydro-4-(trifluoromethyl)-2-(1H)-quinazolinones were found to be potent non-nucleoside reverse transcriptase inhibitors (NNRTIs) of human immunodeficiency virus type-1 (HIV-1). The 4-alkenyl-3, 4-dihydro-4-(trifluoromethyl)-2-(1H)-quinazolinones DPC 082 and DPC 083 and the 4-alkynyl-3, 4-dihydro-4-(trifluoromethyl)-2-(1H)-quinazolinones DPC 961 and DPC 963 were found to exhibit low nanomolar potency toward wild-type RF virus (IC(90) = 2.0, 2.1, 2.0, and 1.3 nM, respectively) and various single and many multiple amino acid substituted HIV-1 mutant viruses. The increased potency is combined with favorable plasma serum protein binding as demonstrated by improvements in the percent free drug in human plasma when compared to efavirenz: 3.0%, 2.0%, 1.5%, 2. 8%, and 0.2-0.5% for DPC 082, DPC 083, DPC 961, DPC 963, and efavirenz, respectively.

Benzothiadiazine non-nucleoside reverse transcriptase inhibitors (NNRTIs) of HIV have been synthesized via a novel process to afford active inhibitors, with the most potent compound exhibiting an IC90 = 180 nM in a whole cell assay. The 2,2-dioxide-1H-2,1,3-benzothiadiazine ring system was constructed in one step from 2-amino-5-chlorobenzonitrile.

Two series of benzoxazinones differing in the aromatic substitution pattern were prepared and evaluated as HIV-1 reverse transcriptase inhibitors. The 5-fluoro (5a-d) and 6-nitro (5e-h) substituted compounds displayed activity comparable or better than Efavirenz, the lead structure of the series.

The preparation of unsymmetrical cyclic ureas bearing novel biaryl indazoles as P2/P2' substituents was undertaken, utilizing a Suzuki coupling reaction as the key step. Compound 6i was equipotent to the lead compound of the series SE063.

Efavirenz (SUSTIVA) is a potent non-nucleoside reverse transcriptase inhibitor. Due to the observation of breakthrough mutations of the reverse transcriptase enzyme during Efavirenz therapy, we sought to develop an optimized second generation series. To that end, SAR of the substituents on the aromatic ring was undertaken and the results are summarized here. The 5,6-difluoro (4f) and the 6-methoxy (4m) substituted benzoxazinones were determined to be equipotent, and as a result such substitution patterns will be incorporated in second generation scaffolds.

A series of alkyl substituted P1/P1' analogs was prepared in an attempt to increase translation of the 3-aminoindazole class of HIV protease inhibitors. Increasing the lipophilicity of the P1/P1' residues dramatically improved translation of enzyme activity to antiviral activity in the whole cell assay.

Using the structural information gathered from the X-ray structures of various cyclic urea/HIVPR complexes, we designed and synthesized many nonsymmetrical P2/P2'-substituted cyclic urea analogues. Our efforts concentrated on using an indazole as one of the P2 substituents since this group imparted enzyme (Ki) potency as well as translation into excellent antiviral (IC90) potency. The second P2 substituent was used to adjust the physical and chemical properties in order to maximize oral bioavailability. Using this approach several very potent (IC90 11 nM) and orally bioavailable (F% 93-100%) compounds were discovered (21, 22). However, the resistance profiles of these compounds were inadequate, especially against the double (I84V/V82F) and ritonavir-selected mutant viruses. Further modification of the second P2 substituent in order to increase H-bonding interactions with the backbone atoms of residues Asp 29, Asp 30, and Gly 48 led to analogues with much better resistance profiles. However, these larger analogues were incompatible with the apparent molecular weight requirements for good oral bioavailability of the cyclic urea class of HIVPR inhibitors (MW < 610).

Cyclic urea SD146, a potent HIV protease inhibitor bearing a flat resistance profile, possessed poor solubility and bioavailability, which precluded further development of the compound. In an effort to improve upon the pharmacokinetic profile of the compound, several analogs modified at the P1/P1' residues were prepared and evaluated. Several of those compounds displayed significant improvement of physical properties.

Cyclic ureas containing 3-aminoindazole P2/P2' groups are extremely potent inhibitors of HIV protease. The parent 3-aminoindazole 6 showed a Ki < 0.01 nM but poor translation of enzyme activity to antiviral activity was observed. A series of 3-alkylaminoindazoles revealed that translation improved with increasing lipophilicity. An X-ray crystal structure of 6 bound to HIV protease was obtained.

Two series of cyclic ureas modified at the P1/P1' residue were prepared and evaluated for HIV protease inhibition and whole cell antiviral activity. Compounds 8b, 10 (3- and 4-pyridylmethyl analogs) and 6b (4-methoxy analog) showed significant improvement in antiviral activity relative to lead compounds DMP323 and DMP 450.

We have studied the population dynamics in response to selective drug pressure of mixtures of wild-type and mutant HIV viruses exposed to either an inhibitor of the viral protease or a nonnucleoside allosteric inhibitor of the viral reverse transcriptase. In order to quantitate mutant virus present in a mixed population, we developed a selective plaque assay, which appears to be generally applicable to population dynamics studies where the viruses in question differ in the sensitivity to a given drug by at least 10-fold. In this assay system, the titer of virus in a mixture is measured in the absence and presence of a concentration of a specific inhibitor known to suppress virus replication by 99%. Virus detected in the presence of inhibitor corresponds to mutant virus, whereas detection in the absence of drug results in quantitation of the total virion population. Wild-type virus is then estimated by difference. Utilizing this system we studied the fate of mixtures of wild-type and the protease-resistant mutant variant I84V in the presence and absence of the cyclic urea HIV protease inhibitor, DMP 450. We also examined the dynamics of mixtures of wild-type and the resistant mutant variant, L100I, in the presence and absence of the drug DMP 266. In both systems we demonstrated that in the absence of drug, mutant virus is at a selective disadvantage for growth compared to wild-type, whereas in the presence of a specific inhibitor, mutant virus exhibits the selective growth advantage over wild-type virus. Better understanding of HIV population dynamics may allow the development of superior inhibitors and the careful application of combination therapy in the clinical setting., (Copyright 1997 Academic Press.)

Re-examination of the design of the cyclic urea class of HIV protease (HIVPR) inhibitors suggests a general approach to designing novel nonpeptide cyclic HIVPR inhibitors. This process involves the inversion of the stereochemical centers of the core transition-state isostere of the linear HIVPR inhibitors and cyclization of the resulting core using an appropriate cyclizing reagent. As an example, this process is applied to the diamino alcohol class of HIVPR inhibitors to give tetrahydropyrimidinones. Conformational analysis of the tetrahydropyrimidinones and modeling of its interaction with the active site of HIVPR suggested modifications which led to very potent inhibitors of HIVPR (24 with a Ki = 0.018 nM). The X-ray crystallographic structure of the complex of 24 with HIVPR confirms the analysis and modeling predictions. The example reported in this study and other examples that are cited indicate that this process may be generally applicable to other linear inhibitors.

We present several novel P1/P1' substituents that can replace the characteristic benzyl P1/P1' moiety of the cyclic urea based HIV protease inhibitor series. These substituents typically provide 5-10-fold improvements in binding affinity compared to the unsubstituted benzyl analogs. The best substituent was the 3,4-(ethylenedioxy)benzyl group. Proper balancing of the molecule's lipophilicity facilitated the transfer of this improved binding affinity into a superior cellular antiviral activity profile. Several analogs were evaluated further for protein binding and resistance liabilities. Compound 18 (IC90 = 8.7 nM) was chosen for oral bioavailability studies based on its log P and solubility profile. A 10 mg/kg dose in dogs provided modest bioavailability with Cmax = 0.22 microg/mL. X-ray crystallographic analysis of two analogs revealed several interesting features responsible for the 3,4-(ethylenedioxy)benzyl-substituted analog's potency: (1) Comparing the two complexes revealed two distinct binding modes for each P1/P1' substituent; (2) The ethylenedioxy moieties are within 3.6 A of Pro 81 providing additional van der Waals contacts missing from the parent structure; (3) The enzyme's Arg 8 side chain moves away from the P1 substituent to accommodate the increased steric volume while maintaining a favorable hydrogen bond distance between the para oxygen substituent and the guanidine NH.

Expression of the human immunodeficiency virus type 1 (HIV) protease in cultured cells leads to apoptosis, preceded by cleavage of bcl-2, a key negative regulator of cell death. In contrast, a high level of bcl-2 protects cells in vitro and in vivo from the viral protease and prevents cell death following HIV infection of human lymphocytes, while reducing the yields of viral structural proteins, infectivity, and tumor necrosis factor alpha. We present a model for HIV replication in which the viral protease depletes the infected cells of bcl-2, leading to oxidative stress-dependent activation of NF kappa B, a cellular factor required for HIV transcription, and ultimately to cell death. Purified bcl-2 is cleaved by HIV protease between phenylalanine 112 and alanine 113. The results suggest a new option for HIV gene therapy; bcl-2 muteins that have noncleavable alterations surrounding the HIV protease cleavage site.

DMP 323, a C-2-symmetrical cyclic urea, is representative of a new class of inhibitors of human immunodeficiency virus protease. In this study, we correlate the potent antiviral activity of DMP 323 in acute infections with antiprotease activity assessed by monitoring the inhibition of the processing of viral gag precursor polyprotein from chronically infected lymphoid and monocytoid cell lines. Electron microscopic examination confirmed that the inhibition of gag processing was associated with the production of immature viral particles. Reduction of DMP 323 in the environment of unprocessed gag viral particles did not result in the resumption of gag processing for at least 72 h.

The enhancement or inhibition of synthesis of specific proteins by IFN is believed to cause subsequent IFN-induced biological responses. The roles of most of these proteins in the biological responses induced by the IFNs, for example, inhibition of virus replication and inhibition of cell growth, remain largely unknown. Our recent research has focused on the induction and synthesis of an IFN-induced 15-kDa protein. In this report we show that human lymphocytes and monocytes, after treatment with IFN-beta, release into the medium an IFN-induced 15-kDa protein. At 24 h after induction of the 15-kDa protein in lymphocytes or monocytes, more than 50% of the total 15-kDa protein is in the medium. The human monocytic cell line THP-1 also releases 15-kDa protein into the medium after its induction by IFN-beta. An intracellular half-life of 12 h has been calculated for the 15-kDa protein in monocytes and THP-1 cells. The exocellular release of the 15-kDa protein by lymphocytes and monocytes suggests that 1) it may have an intercellular signaling role and 2) it may be an in vivo mediator of some of the biological responses induced by IFN.

Using recombinant DNA technology, a 15-kD interferon (IFN)-induced protein and its 17-kD precursor have been expressed in Escherichia coli to obtain sufficient quantities of each protein for the investigation of their biological roles. Both the 15-kD and 17-kD proteins have been purified to homogeneity and crystallized. The recombinant 15-kD protein has an identical reversed-phase HPLC elution profile to that of the native 15-kD protein purified from human cells. Furthermore, the recombinant 15-kD and 17-kD proteins have identical amino- and carboxy-terminal amino acid sequences to those predicted from the DNA sequence. The native and recombinant 15-kD proteins give identical tryptic peptide maps, and the recombinant 17-kD protein gives only one additional tryptic peptide. We conclude that the recombinant 17-kD and 15-kD proteins are identical to the 17-kD precursor and the 15-kD stable product synthesized in human cells in response to IFN stimulation. In addition, we have demonstrated that the recombinant 17-kD precursor protein can be converted to the 15-kD protein by cytoplasmic extracts of human cells.

An interferon-induced 15-kDa protein is synthesized from a precursor of higher molecular weight; the precursor contains 165 amino acids (17 kDa), whereas the stable product (15 kDa) contains 156 amino acids. The stable 15-kDa form is derived from the precursor 17-kDa form by the removal of eight amino acids from the COOH terminus and the methionine from the NH2 terminus. The existence of the precursor 17-kDa protein can be demonstrated after brief periods of in vivo labeling with [35S]methionine and by translation of mRNA in vitro.