Cobalamin as a regulator of serum and cerebrospinal fluid levels of normal prions

Prion Protein on Human Leukocytes Is Reduced in Iron Deficiency - Possible Implications for Age-related Macular Degeneration?

MATERIALS AND METHODS

Patients presenting to the department of ophthalmology of the Medical University of Graz for reasons unrelated to prion diseases were enrolled. Parameters of iron metabolism, including ferritin and soluble transferrin receptor were measured by routine laboratory tests. Serum prion protein was determined by enzyme-linked immunosorbent assay. Surface prion protein on CD14⁺ monocytes and CD4⁺ T cells was analyzed by fluorescence activated cell sorting.

RESULTS

95 patients were enrolled. Soluble transferrin receptor correlated significantly with prion protein levels on CD14⁺POM1⁺ monocytes (P = .001, r = -0.7) and on CD4⁺POM1⁺ T cells (P = .01, r = -0.62).

CONCLUSION

Our findings suggest a connection between the physiological function of the prion protein and iron metabolism in humans.

A retrospective study of 23 cases with subacute combined degeneration

PURPOSE

To study retrospectively the diverse presentations, ancillary tests and neuroimaging in patients with subacute combined degeneration (SCD).

METHODS

Twenty-three Chinese patients with SCD were included in this study. The clinical presentations and laboratory data including comprehensive metabolic panel, serum folic acid, vitamin B12 levels, gastroscopy and images of spinal cord on magnetic resonance imaging (MRI) were evaluated. Rating scales for localizations of lesions and functional disabilities were used to define the severity of neurological impairment.

RESULTS

No difference was found between men and women in the age of disease onset. For most of the patients, sensory symptoms, oftentimes as initial symptoms, occurred earlier than motor symptoms. The signs of the disease were more obvious than the symptoms. Six patients had sensory deficit levels mimicking transverse myelopathy. Anemia was not always detected in our patients with SCD. Normal or even elevated serum levels of vitamin B12 were found in seven patients. Spinal cord lesions on MRI were observed in six patients and the clinical and neuroimaging findings were not necessarily consistent.

CONCLUSIONS

The sensory symptoms occur earlier than the motor symptoms in SCD patients. SCD patients may have sensory deficit level. Normal or even elevated serum levels of vitamin B12 may occur in patients with SCD.

Low levels of cobalamin, epidermal growth factor, and normal prions in multiple sclerosis spinal cord

We have previously demonstrated that multiple sclerosis (MS) patients have abnormal cerebrospinal fluid (CSF) levels of the key myelin-related molecules cobalamin (Cbl), epidermal growth factor (EGF), and normal cellular prions (PrP(C)s), thus confirming that some CSF abnormalities may be co-responsible for remyelination failure. We determined the levels of these three molecules in post-mortem spinal cord (SC) samples taken from MS patients and control patients. The control SC samples, almost all of which came from non-neurological patients, did not show any microscopic lesions of any type. All of the samples were supplied by the U.K. MS Tissue Bank. The Cbl, EGF, and PrP(C) levels were determined using enzyme-linked immunosorbent assays. The SC total homocysteine level was determined using a competitive immunoenzymatic assay. CSF samples, taken from a further group of MS patients, were used for the assay of holo-transcobalamin (holo-TC) levels. The Cbl, EGF, and PrP(C) levels were significantly decreased in MS SCs in comparison with controls and, paradoxically, the decreased Cbl levels were associated with decreased SC levels of homocysteine, a biochemical marker of Cbl deficiency. The trends of EGF and PrP(C) levels paralleled those previously found in CSF, whereas that of Cbl was the opposite. There was no significant difference in CSF holo-TC levels between the MS patients and the controls. Given that we have previously demonstrated that Cbl positively regulates central nervous system EGF levels, it is conceivable that the low EGF levels in the MS SC may be causally related to a local decrease in Cbl levels. Only PrP(C) levels were invariably decreased in both the SC and CSF regardless of the clinical course of the disease. These findings suggest that the simultaneous lack of Cbl, EGF, and PrP(C)s may greatly hamper the remyelination process in MS patients, because they are key molecules of the machinery for remyelination.