# Database Queries¶

## Introduction¶

ComptoxAI is largely built around two databases:

1. A graph database of entities, their semantic types, and the relationships that link these entities. This is implemented using Neo4j.

2. A feature database that maps the entities in the graph database to structured documents describing various aspects of those entities. This is implemented using MongoDB.

This document is meant to show how you can interact with these two databases to learn meaningful things about computational toxicology data. We’ll start by taking at how these data are formatted in the source database, and then we’ll discuss how to retrieve and manipulate them using ComptoxAI.

Tip

ComptoxAI uses two separate databases because current graph database implementations aren’t especially good at handling large amounts of feature data efficiently. It turns out that analyses can be conducted faster when you isolate graph data into a graph database and quantitative feature data into a document store (like MongoDB).

A major goal of the ComptoxAI Python package is to make the integration of these two databases as painless as possible to the end user. We’re keeping an eye out for new graph database technologies that would allow us to integrate the databases into a single resource without having to sacrifice performance.

## Example - Hydroxychloroquine¶

### Graph database representation¶

For example, consider the chemical hydroxychloroquine (118-42-3 | DTXSID8023135). Hydroxychloroquine’s node in the graph database looks like:

{
"identity": 32519,
"labels": [
"Chemical",
"NamedIndividual",
"Resource"
],
"properties": {
"commonName": "Hydroxychloroquine",
"inchiKey": "XXSMGPRMXLTPCZ-UHFFFAOYSA-N",
"inchi": "InChI=1S/C18H26ClN3O/c1-3-22(11-12-23)10-4-5-14(2)21-17-8-9-20-18-13-15(19)6-7-16(17)18/h6-9,13-14,23H,3-5,10-12H2,1-2H3,(H,20,21)",
"xrefDrugbank": "DB01611",
"xrefMeSHUI": "D006886",
"xrefPubchemSID": 315673741,
"xrefCasRN": "118-42-3",
"uri": "http://jdr.bio/ontologies/comptox.owl#chem_hydroxychloroquine",
"chemicalIsInCTD": true,
"chemicalIsDrug": true,
"xrefPubchemCID": 3652,
"xrefDtxsid": "DTXSID8023135"
}
}


These are mainly just identifiers, but things get more interesting when we look at relationships to other nodes in the graph database. At the time of writing, the node is directly linked to 480 other nodes in the database. Here is one of those relationships:

{
"identity": 1210864,
"start": 32519,
"end": 19842,
"type": "CHEMICALASSOCIATESWITHDISEASE",
"properties": {}
}


In this case, the start node (32519) is hydroxychloroquine, the end node (22421) is spinal cord compression:

{
"identity": 19842,
"labels": [
"Resource",
"NamedIndividual",
"Disease"
],
"properties": {
"commonName": "Spinal Cord Compression",
"uri": "http://jdr.bio/ontologies/comptox.owl#dis_spinalcordcompression",
"xrefMeSH": "D013117"
}
}


Or in other words:

\langle\textit{hydroxychloroquine}\rangle\,\texttt{CHEMICAL\_ASSOCIATES\_WITH\_DISEASE}\,\langle\textit{spinal cord compression}\rangle

### Feature database representation¶

Quantitative feature data are stored in MongoDB as structured documents that look similar to JSON documents. These documents include fields such as chemical molecular descriptors, assay measurements, gene loci, literature references, biochemical values, miscellaneous free text, and others.