numpy.uint(): transform float to uint gives [Totally] different results with large numbers

Question

I was experimenting with numpy.uint() and numpy.around()

Here is what I have done:

>>> matrix = np.matrix([-32, -32.0, -3.91886975727153e-15])
>>> matrix
    matrix([[-3.20000000e+01, -3.20000000e+01, -3.91886976e-15]])
>>> np.uint(matrix)
...         
    matrix([[4294967264, 4294967264,          0]], dtype=uint32)
>>> np.around(matrix)
...                         
    matrix([[-32., -32.,  -0.]])
>>> np.uint(np.around(matrix))
...                         
    matrix([[4294967264, 4294967264,          0]], dtype=uint32)

---

Same happends with np.uint8 np.uint16 but with different values:

np.uint8(np.around(matrix))
matrix([[224, 224,   0]], dtype=uint8)

np.uint16(np.around(matrix))                        
matrix([[65504, 65504,     0]], dtype=uint16)

Why uint functions act that way?