C#

public override void LoadChildren()
        {
            this.Items.Clear();
            List<Operation> lstOp = DataBAse.GetAllOperations();
            foreach (Operation op in lstOp)
            {
                this.Items.Add(new TreeViewItemViewModel(op));
            }
        }

public bool IsExpanded
        {
            get 
            {
                return _isExpanded; 
            }
            set
            {
                if (value != this._isExpanded)
                {
                    this._isExpanded = value;
                    RaisePropertyChanged("IsExpanded");

                    if (this._isExpanded)
                    {
                        this.LoadChildren();
                    }
                }
            }
        }

A less labor intensive approach would be to use the C++ MFC control project. This will do much of the heavy lifting for you and will greatly simplify your development effort. Once you have your control created, you could just use TLBIMP.EXE to generate an interop assembly containing the RCW's for you to interop with. I would recommend this approach.

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using System.Threading;
using System.Data.SqlClient;

namespace ConsoleApplication3
{
    class Program
    {
        public static void Main();
           
            string logType = "Application";
            EventLog ev = new EventLog(logType, System.Environment.MachineName);
            EventLogEntry Entry = ev.Entries;

            SqlConnection SysMonConn = new SqlConnection(@"Provider = sqloledb.1" +
                                                         "Source = 192.168.x.y,1433" +
                                                         "Database = EventLogs" +
                                                         "Trusted_Connection=yes;" +
                                                         "user id=a;" +
                                                         "password=b;" +
                                                         "connection timeout=30;");
        }        
          SysMonConn.Open();
            SqlCommand SMCommand = SysMonConn.CreateCommand();
            SMCommand.CommandText = "INSERT INTO dbo.EventTable(Category, ComputerName," +
                                    "Message, SourceName, TimeWritten,Type, UserName)";
            SMCommand.Parameters.Add("@Category", System.Data.SqlDbType.NVarChar, 50) = Entry.Category;
            SMCommand.Parameters.Add("@ComputerName", System.Data.SqlDbType.NVarChar, 50) = Entry.MachineName;
            SMCommand.Parameters.Add("@Message", System.Data.SqlDbType.NVarChar, 250) = Entry.Message;
            SMCommand.Parameters.Add("@SourceName", System.Data.SqlDbType.NVarChar, 50) = Entry.Source;
            SMCommand.Parameters.Add("@TimeWritten", System.Data.SqlDbType.NVarChar, 50) = Entry.TimeWritten;
            SMCommand.Parameters.Add("@Type", System.Data.SqlDbType.NVarChar, 50) = Entry.EntryType;
            SMCommand.Parameters.Add("@UserName", System.Data.SqlDbType.NVarChar, 50) = Entry.UserName;
          
        ev.Close();
        
    }
}