Biology subjects

Aleman, J.

Publications and source records attributed to Aleman, J..

5 recordsLinked to original sources

bioRxiv2025

Recapitulation of clinical and molecular hallmarks of lipid-induced hepatic insulin resistance in a zonated, vascularized human liver acinus microphysiological system during metabolic dysfunction-associated steatotic liver disease (MASLD) progression

Metabolic dysfunction-associated steatotic liver disease (MASLD) impacts ca. 30% of the global population and is very heterogeneous making it a challenge to produce therapeutics. The heterogeneity arises from genetics, co-morbidities, the microbiome and lifestyle. To help address this challenge, we have refined the human vascularized liver acinus microphysiological system (vLAMPS), which provides an all-human platform for drug development, in line with recently updated federal requirements for the use of New Approach Methodologies (NAMs). By introducing clinically relevant media perturbations and employing several diverse and reproducible in situ and systemic measurements, we show that the vLAMPS can recapitulate key structural and functional aspects of normal physiology, acinus zonation, and all stages of MASLD progression including stellate cell activation and fibrosis. Importantly, in this study we also demonstrate that several hallmarks of lipid-induced hepatic insulin resistance paralleled MASLD progression. These included diminution of insulin receptor substrate 2 (IRS2) protein, compromised insulin receptor mediated insulin clearance, enhanced pericentral lipid accumulation, increased VLDL secretion, and enhanced hepatic glucose output mediated by increased periportal nuclear translocation of FOXO1. These results suggest that the mechanisms underlying MASLD progression in vLAMPS are clinically relevant and support the tenable hypothesis that the hepatic insulin resistant state plays both a causal and consequential role in a vicious cycle driving disease progression.

bioengineering↗

bioRxiv2024

A metabolic-dysfunction associated steatotic liver acinus biomimetic induces pancreatic islet dysfunction in a coupled microphysiology system

Preclinical and clinical studies suggest that lipid-induced hepatic insulin resistance is a primary defect that predisposes to dysfunction in pancreatic islets, implicating a perturbed liver-pancreas axis underlying the comorbidity of T2DM and MASLD. To investigate this hypothesis, we developed a human biomimetic microphysiological system (MPS) coupling our vascularized liver acinus MPS (vLAMPS) with primary islets on a chip (PANIS) enabling MASLD progression and islet dysfunction to be quantitatively assessed. The modular design of this system (vLAMPS-PANIS) allows intra-organ and inter-organ dysregulation to be deconvoluted. When compared to normal fasting (NF) conditions, under early metabolic syndrome (EMS) conditions, the standalone vLAMPS exhibited characteristics of early stage MASLD, while no significant differences were observed in the standalone PANIS. In contrast, with EMS, the coupled vLAMPS-PANIS exhibited a perturbed islet-specific secretome and a significantly dysregulated glucose stimulated insulin secretion (GSIS) response implicating direct signaling from the dysregulated liver acinus to the islets. Correlations between several pairs of a vLAMPS-derived and a PANIS-derived secreted factors were significantly altered under EMS, as compared to NF conditions, mechanistically connecting MASLD and T2DM associated hepatic factors with islet-derived GLP-1 synthesis and regulation. Since vLAMPS-PANIS is compatible with patient-specific iPSCs, this platform represents an important step towards addressing patient heterogeneity, identifying complex disease mechanisms, and advancing precision medicine.

bioengineering↗

bioRxiv2022

The archaeological potential of the northern Luangwa Valley, Zambia: the Luwumbu basin.

The Luangwa Basin, Zambia, which forms part of the Zambezi drainage, is strategically located between the Central African plateau and the East African Rift system. The Luangwa River and major tributaries, such as the Luwumbu River, are perennial water sources supporting essential resources that sustain human communities and a rich and diverse fauna and flora. The archaeological record of Luangwa is relatively unknown, despite early archaeological exploration hinting at its potential. Recent research in the southern Luangwa valley, however, suggests that it preserves a long record of hominin occupation spanning the Early to Late Stone Age. The research described here details fieldwork carried out in northeastern Luangwa, in the Luwumbu Basin, that confirms that a relatively deep package of Quaternary deposits, containing evidence of the Stone Age occupation of the region persists in the upper piedmont zone.

evolutionary biology↗

bioRxiv2021

Engineering a thixotropic and biochemically tunable hyaluronan and collagen bioink for biofabrication of multiple tissue construct types

The field of three-dimensional (3D) bioprinting has advanced rapidly in recent years. Significant reduction in the costs associated with obtaining functional 3D bioprinting hardware platforms is both a cause and a result of these advances. As such, there are more laboratories than ever integrating bioprinting methodologies into their research. However, there is a lack of standards in the field of biofabrication governing any requirements or characteristics to support cross-compatibility with biomaterial bioinks, hardware, and different tissue types. Here we describe a modular extracellular matrix (ECM) inspired bioink comprised of collagen and hyaluronic acid base components that: 1) employ reversible internal hydrogen bonding forces to generate thixotropic materials that dynamically reduce their elastic moduli in response to increased shear stress, thus enabling increased compatibility with printing hardware; and 2) modular addons in the form of chemically-modified fibronectin and laminin that when covalently bound within the bioink support a variety of tissue types, including liver, neural, muscle, pancreatic islet, and adipose tissue. These features aim to accelerate the deployment of such bioinks for tissue engineering of functional constructs in the hands of various end users.

bioengineering↗

bioRxiv2019

pumilio regulates sleep homeostasis in response to chronic sleep deprivation in Drosophila melanogaster

Recent studies have identified the Drosophila brain circuits involved in the sleep/wake switch and have pointed to the modulation of neuronal excitability as one of the underlying mechanisms triggering sleep need. In this study we aimed to explore the link between the homeostatic regulation of neuronal excitability and sleep behavior in the circadian circuit. For this purpose, we selected the neuronal homeostasis protein Pumilio (Pum), whose main function is to repress protein translation and has been linked to modulation of neuronal excitability during chronic patterns of altered neuronal activity. Here we explore the effects of Pum on sleep homeostasis in Drosophila melanogaster, which shares most of the major features of mammalian sleep homeostasis. Our evidence indicates that Pum is necessary for sleep rebound and that its effect is more pronounced during chronic sleep deprivation (84 hours) than acute deprivation (12 hours). Knockdown of pum, results in a reduction of sleep rebound during acute sleep deprivation and the complete abolishment of sleep rebound during chronic sleep deprivation. These behavioral changes were associated with accompanying changes in the expression of genes involved in the regulation of neuronal excitability. Interestingly, pum knockdown also increased baseline daytime sleep, suggesting that Pum differentially regulates rebound and normal sleep. Based on these findings, we propose that Pum is a critical regulator of sleep homeostasis through neural adaptations triggered during sleep deprivation and induces rebound sleep by altering neuronal excitability.

neuroscience↗