Biology subjects

Robbins, B.

Publications and source records attributed to Robbins, B..

4 recordsLinked to original sources

bioRxiv2025

Sulbactam-Durlobactam Plus Ceftriaxone Dosing and Novel Treatment Regimens for Mycobacterium abscessus Lung Disease

BackgroundIDSA guideline-based therapy achieves sputum culture conversion rates in 20-34% of patients with Mycobacterium abscessus (MAB) lung disease (LD). Double-{beta}-lactam combinations have been proposed to improve cure, based on time-kill curves. MethodsWe performed minimum inhibitory concentrations (MICs) experiments followed by hollow fiber system model of MAB-LD (HFS-MAB) exposure-effect studies with sulbactam-durlobactam administered every 8h (q8h), q12h, and q24h, to identify target exposures. Next, the sulbactam-durlobactam target exposure plus ceftriaxone was administered in the HFS-MAB inoculated with three different MAB isolates, as was the sulbactam-durlobactam-ceftriaxone combination with epetraborole and omadacycline (SDCEO).{gamma} -slopes (kill-speed) were calculated for all regimens. The minimal sulbactam-durlobactam clinical doses that achieved target exposure were identified using Monte Carlo experiments. ResultsCeftriaxone reduced sulbactam-durlobactam MICs by 8-tube dilutions. In the HFS-MAB, sulbactam-durlobactam microbial kill and antimicrobial resistance were linked to % time concentration persists above MIC (%TMIC), with target exposure of 50%. Sulbactam-durlobactam killed 3.85 log10 CFU/mL below day 0 burden (B0) with regrowth. Sulbactam-durlobactam plus ceftriaxone killed without regrowth and demonstrated Bliss additivity.{gamma} of bacterial population in >95% of virtual subjects were 2.28 (0.97-4.80) log10 CFU/mL/day for sulbactam-durlobactam-ceftriaxone and 2.91 (1.65-4.93) log10 CFU/mL/day for SDCEO. The optimal sulbactam-durlobactam dose co-administered with ceftriaxone was 2G q8h for creatinine clearance >90 mL/min, 2G q12h for 60-90 mL/min, 1G q12h for [≥]30 to <60 mL/min, and 1G q24h for <30 mL/min. ConclusionSulbactam-durlobactam-ceftriaxone achieved the highest microbial kill encountered so far in the HFS-MAB. Sulbactam-durlobactam-ceftriaxone should be tested as the backbone for novel treatment shortening regimens.

pharmacology and toxicology↗

bioRxiv2022

Analysis of D- and L- Isomers of (Meth)amphetamine in Human K2EDTA Plasma

Methamphetamine and its metabolite amphetamine are frequently abused drugs. Whether obtained legally or from clandestine laboratories it is of relevance to determine the chiral makeup of these drugs for investigative purpose. Although urine and oral fluid matrices are commonly offered, less available to independent laboratories are techniques to verify dextro (D-) or levo (L-) (meth)amphetamine from human K2EDTA plasma. This paper outlines the development and validation of a method that includes the addition of internal standard and a two-step liquid-liquid extraction to remove the analytes from human K2EDTA plasma by triple quadrupole mass spectrometry (LC-MS/MS). The assay was validated according to the United States Food and Drug Administration and College of American Pathologists guidelines, including assessment of the following parameters in plasma validation samples: linear range, limit of detection, lower limit of quantitation, matrix effects, inter- and intra-day assay precision and accuracy, carry over, linearity of dilution, matrix effects and stability. The outcome is a validated and reliable method for the determination of D- and L-isomer concentration of meth(amphetamine) human plasma samples that can be easily adopted by independent clinical laboratories.

biochemistry↗

bioRxiv2022

Quantifying 64 drugs, illicit substances, and D- and L- isomers in human oral fluid with liquid-liquid extraction

Although human oral fluid has become more routine for quantitative drug detection in pain management, detecting a large scope of medications and substances is costly and technically challenging for laboratories. This paper presents a quantitative assay for 64 pain medications, illicit substances, and drug metabolites in human oral fluid. The novelty of this assay is that it was developed on an older model AB SCIEX 4000 instrument and renders obscure the need for more technical and expensive laboratory equipment. This method includes addition of internal standard and a 2-step liquid-liquid extraction and dry-down step to concentrate and clean the samples. The samples were suspended in 50% MeOH in water and separation and detection was accomplished using triple quadrupole mass spectrometry (LC-MS/MS). Separation was achieved using reverse-phase liquid chromatography with detection by LC-MS/MS. A second injection was done in negative mode to determine THC-COOH concentration as an indicator of THC. An aliquot of the (already) extracted samples was analyzed for D- and L- isomers of amphetamine and methamphetamine using a chiral column. The standard curve spanned from 5 to 2000 ng/mL for most of the analytes (1 to 2000 ng/mL for fentanyl and THC-COOH) and up to 1000 ng/mL for 13 analytes. Pregabalin and gabapentin ranged from 25 to 2000 ng/mL. The result is a low-cost method for the sensitive detection of a wide-ranging oral fluid menu for pain management. This assay has a high sensitivity, and good precision and accuracy for all analytes with an older model mass spectrometer.

biochemistry↗

bioRxiv2021

Regulation of Brain Primary Cilia Length by MCH Signaling: Evidence from Pharmacological, Genetic, Optogenetic and Chemogenic Manipulations

The melanin concentrating hormone (MCH) system is involved in numerous functions including energy homeostasis, food intake, sleep, stress, mood, aggression, reward, maternal behavior, social behavior, and cognition. MCH acts on a G protein-coupled receptor MCHR1, which expresses ubiquitously in the brain and localizes to neuronal primary cilia. Cilia act as cells antennas and play crucial roles in cell signaling to detect and transduce external stimuli to regulate cell differentiation and migration. Cilia are highly dynamic in terms of their length and morphology; however, it is not known if cilia length is causally regulated by MCH system activation in-vivo. In the current work, we examined the effects of the activation and inactivation of MCH system on cilia lengths by using different methodologies, including pharmacological (MCHR1 agonist and antagonist GW803430), germline and conditional genetic deletion of MCHR1 and MCH, optogenetic, and chemogenetic (Designer Receptors Exclusively Activated by Designer Drugs (DREADD)) approaches. We found that stimulation of MCH system either directly through MCHR1 activation, or indirectly through optogenetic and chemogenetic- mediated excitation of MCH neurons, causes cilia shortening. Contrarily, inactivation of MCH signaling through pharmacological MCHR1 blockade or through genetic manipulations - germline deletion of MCHR1 and conditional ablation of MCH neurons - induces cilia lengthening. Our study is the first to uncover the causal effects of the MCH system in the regulation of the length of brain neuronal primary cilia. These findings place MCH system at a unique position in the ciliary signaling in physiological and pathological conditions, and implicate cilia MCHR1 as a potential therapeutic target for the treatment of pathological conditions characterized by impaired cilia function.

molecular biology↗