Biology subjects

Hamed, A.

Publications and source records attributed to Hamed, A..

4 recordsLinked to original sources

bioRxiv2026

MechAInistic: An LLM-guided Multi-Agent System for Reasoning over Genome-Scale Constraint-Based Metabolic Models

LLM agents are increasingly used for scientific reasoning, but their fluent-sounding outputs can diverge from verifiable computational evidence, limiting their reliability for biomedical hypothesis generation. We developed MechAInistic, a multi-agent system in which an independently configured Reviewer agent supervises a planning Architect agent at each stage of the workflow, with all reasoning grounded in executable mechanistic-model analyses rather than language-model text alone. The Reviewer scores plans and intermediate results against pre-specified rubrics and triggers re-planning or re-execution when scores fall below threshold, producing an auditable chain from a natural-language question to model-derived evidence and cited literature. We instantiate the system over paired constraint-based metabolic models using COBRApy, supporting pathway comparison, perturbation analysis, drug-target exploration, and literature interpretation across healthy and disease states. We evaluated MechAInistic on two immune-cell therapeutic hypothesis-generation tasks. For rheumatoid arthritis versus healthy naive B-cell models, it identified mitochondrial metabolic rewiring and nominated Devimistat/CPI-613 as an investigational OGDH-centered hypothesis. For multiple sclerosis CD4+ Th17 versus healthy models, it identified NADP-dependent isocitrate dehydrogenase as a candidate target and proposed ivosidenib, with vorasidenib as a mechanistically complementary alternative. Comparator analyses against general-purpose LLM systems showed that plausible biological narratives can lack auditable model grounding, whereas MechAInistic preserves the computational reasoning path from prompt to result. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/723319v4_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@4e591eorg.highwire.dtl.DTLVardef@1bceee3org.highwire.dtl.DTLVardef@e7a0f4org.highwire.dtl.DTLVardef@f80b3a_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

bioRxiv2025

Plasma lipidome dysregulation in frontotemporal dementia reveals shared, genotype-specific, and severity-linked alterations

Developing new treatment strategies for frontotemporal dementia (FTD) and other forms of neurodegeneration requires biomarkers to monitor disease progression. Dysregulated brain lipid metabolism, particularly sphingolipids enriched in the nervous system, is a key feature of neurodegeneration. However, plasma lipids have been investigated less for their potential as biomarkers than brain imaging and serum proteins. Here we examined the plasma lipidomes of a cohort of heterozygous carriers of gene variants associated with autosomal dominant familial FTD (including GRN, C9orf72, and MAPT loci), comparing them with aged-matched controls. In general, FTD subjects exhibited increases in plasma levels of specific species of gangliosides (GM3(d18:1_16:0), GM3(d18:1_18:0), and GM3(d18:1_24:1)) and ceramide (Cer(d18:1_23:0)) and selected polyunsaturated triacylglycerols (TG). Other species of ceramides (Cer(d18:0_22:0)), phosphatidylethanolamine (PE(18:0_24:0)), and sphingomyelin (SM(38:0)) were reduced in plasma of FTD subjects. Levels of glucosylsphingosine (GlcSph(d18:1)) were elevated specifically in GRN carriers, SM(34:1) was reduced in C9orf72 carriers, and TG(16:0_18:1_20:3)) were decreased in MAPT variant carriers. Notably, the ganglioside GM3(d18:1_16:0) was consistently elevated across all FTD genetic subtypes. Furthermore, the levels of these lipids correlated with disease severity in FTD patients. Our findings suggest that specific plasma lipid changes, notably several sphingolipids, may be useful biomarkers for FTD disease or progression.

systems biology↗

bioRxiv2023

Spatio-temporal mechanisms of consolidation, recall and reconsolidation in reward-related memory trace

The formation of memories is a complex, multi-scale phenomenon, especially when it involves integration of information from various brain systems. We have investigated the differences between a novel and consolidated association of spatial cues and amphetamine administration, using an in-situ hybridisation method to track the short-term dynamics during the recall testing. We have found that remote recall group involves smaller, but more consolidated groups of neurons, which is consistent with their specialisation. By employing machine learning analysis, we have shown this pattern is especially pronounced in the VTA; furthermore, we also uncovered significant activity patterns in retrosplenial and prefrontal cortices, as well as in the DG and CA3 subfields of the hippocampus. The behavioural propensity towards the associated localisation appears to be driven by the nucleus accumbens, however, further modulated by a trio of the amygdala, VTA and hippocampus, as the trained association is confronted with test experience. These results show that memory mechanisms must be modelled considering individual differences in motivation, as well as covering dynamics of the process.

neuroscience↗

bioRxiv2020

More than a feeling: central amygdala mediates social transfer of information about proximity of danger

To survive, an animal must adequately respond to challenges presented by the environment. Social animals can learn about danger from fear of conspecifics which allows them to avoid predation and other threats without costly, first-hand experience. However, it remains unclear as to whether animals can transmit specific information that helps an individual avoid harm or whether the transmitted social signals simply increase vigilance in a non-specific manner. Here we demonstrate that animals can select appropriate defensive strategies in a novel environment depending on cues from the conspecific and, using opsins targeted to behaviorally activated neurons, identify distinct neuronal circuits in the central amygdala (CeA) that are crucial for choosing a context-appropriate reaction. The identified circuits differ in molecular markers and patterns of connectivity. Thus, we show that social signals carry explicit information about proximity of danger, necessary for choosing a context-appropriate reaction, and that the choosing process is mediated by the CeA circuits.

neuroscience↗