Mapping temporo-parietal and temporo-occipital cortico-cortical connections of the human middle longitudinal fascicle in subject-specific, probabilistic, and stereotaxic Talairach spaces.

Originally, the middle longitudinal fascicle (MdLF) was defined as a long association fiber tract connecting the superior temporal gyrus and temporal pole with the angular gyrus. More recently its description has been expanded to include all long postrolandic cortico-cortical association connections of the superior temporal gyrus and dorsal temporal pole with the parietal and occipital lobes. Despite its location and size, which makes MdLF one of the most prominent cerebral association fiber tracts, its discovery in humans is recent. Given the absence of a gold standard in humans for this fiber tract, its precise and complete connectivity remains to be determined with certainty. In this study using high angular resolution diffusion MRI (HARDI), we delineated for the first time, six major fiber connections of the human MdLF, four of which are temporo-parietal and two temporo-occipital, by examining morphology, topography, cortical connections, biophysical measures, volume and length in seventy brains. Considering the cortical affiliations of the different connections of MdLF we suggested that this fiber tract may be related to language, attention and integrative higher level visual and auditory processing associated functions. Furthermore, given the extensive connectivity provided to superior temporal gyrus and temporal pole with the parietal and occipital lobes, MdLF may be involved in several neurological and psychiatric conditions such as primary progressive aphasia and other aphasic syndromes, some forms of behavioral variant of frontotemporal dementia, atypical forms of Alzheimer's disease, corticobasal degeneration, schizophrenia as well as attention-deficit/hyperactivity Disorder and neglect disorders.

Oncofetal mucin M1 epitope family: characterization and expression during colonic carcinogenesis.

The gastric mucin M1 antigens, markers associated with colonic carcinogenesis, have been characterized by new antimucin monoclonal antibodies (MAbs). These MAbs, obtained against mucins isolated from a human ovarian mucinous cyst (MAbs 19M1, 21M1 and 45M1) and from a pancreatic adenocarcinoma (MAb 96RA), were compared with 5 other anti-M1 mucin MAbs described previously, which characterized the a, b, c, d and e mucin M1 epitopes. Using immunoperoxidase, these new MAbs exclusively stained the surface gastric epithelium of normal human gastro-intestinal tract and reacted with fetal, precancerous and cancerous colonic mucosa, but not with normal colon. Immunoradiofixation studies showed that these new MAbs are directed against 3 epitopes (f, g and h) which are different from the a, b, c, d and e mucin M1 epitopes, though present on the same a immunoreactive high-molecular-weight components (greater than 1,000 kDa) with a density of 1.4 by CsCl-density-gradient ultracentrifugation. M1 antigenicity is characterized by a family of 8 different M1 epitopes which were destroyed with beta-mercaptoethanol (except for the f epitope), sensitive to a 5 hr trypsin treatment and resistant to 5 mM periodate (except for the h epitope). Some epitopes (b, c and d) showed increasing immunoreactivity after 20 mM periodate treatment, suggesting cryptic location. In rat-colon adenocarcinomas, M1 mucin epitopes were masked but could be decrypted using high periodate treatment, similar to normal rat gastric mucosa, thus suggesting the absence of drastic changes in the saccharide coat of the peptide mucin portion bearing M1 epitopes. Cryptic location, periodate resistance, sensitivity to protease and conformational behavior strongly suggest that the peptidic core of gastric (or fetal colonic) mucin plays a role in M1 immunoreactivity. Indeed, the resurgence of M1 antigens during colonic carcinogenesis is due to re-expression of the peptide core of gastric (or fetal colonic) mucins.