Application of raman spectroscopy in pharmaceuticals

Experimental research on the use of Raman spectroscopy as an in- and on-line sensing tool and a complementary characterization technique for pharmaceutical applications is presented in this thesis. In the first chapter following a broad overview, the use of Raman spectroscopy, together with x-ray powder diffraction, scanning electron microscopy (SEM) and differential scanning calorimetry, for multilevel characterization of cryomilled powders, and the melt-grown amorphous phase of griseofulvin, a model active pharmaceutical ingredient (API), is presented and discussed in detail. A key feature was the observation of a broad inelastic background superimposed on the Raman spectra of cryomilled powders, which is attributed to lattice disorder and Mie scattering generated by mechanical processing and sub-micron particle interfaces. In the following chapter, polymorphs of another model API, acetaminophen (APAP), were studied by Raman spectroscopy with supporting information obtained from x-ray diffraction, SEM images and intrinsic dissolution profiles. An important result was the stabilization and characterization of the metastable type II orthorhombic phase of APAP which is highly desired for its unique tabletting properties which are important for pharmaceutical manufacturing. Stabilization of metastable type II APAP was achieved by micronizing or nanocoating stable monoclinic crystallites of type I APAP. In addition, as an Appendix to the thesis, micro-Raman spectroscopy of single crystal APAP as a function of crystal orientation and of temperature was measured to provide an understanding of the lattice properties of APAP for input into models to predict its behavior under mechanical milling conditions widely used in pharmaceutical processing. Molecular behavior obtained from the above studies guided simulated in-line and off-line characterization of griseofulvin as thin gel films made from micronized powders and nanosuspensions. By employing complementary near infrared and Raman imaging for newly developed films, it was possible to extract valuable information on the spatial distribution and crystallinity of the embedded particles in a polymeric matrix at different scales of scrutiny. Chemometrics processing of spectroscopic data for films and nanosuspensions allowed for qualitative and quantitative particle size determinations of the API’s in the films and nanosuspensions. In the final chapter a photonic crystal substrate for surface enhanced Raman spectroscopic (SERS) sensing was employed to detect and study griseofulvin and APAP down to 10-8 M levels with enhancement factors approaching 1099. Detection sensitivities of the aromatic griseofulvin and APAP molecules were also compared with those of less aromatic and non-aromatic energetic molecules in order to understand the Raman enhancement process

Associations between hippocampal morphometry and neuropathologic markers of Alzheimer's disease using 7 T MRI

Hippocampal atrophy, amyloid plaques, and neurofibrillary tangles are established pathologic markers of Alzheimer's disease. We analyzed the temporal lobes of 9 Alzheimer's dementia (AD) and 7 cognitively normal (NC) subjects. Brains were scanned post-mortem at 7 Tesla. We extracted hippocampal volumes and radial distances using automated segmentation techniques. Hippocampal slices were stained for amyloid beta (Aβ), tau, and cresyl violet to evaluate neuronal counts. The hippocampal subfields, CA1, CA2, CA3, CA4, and subiculum were manually traced so that the neuronal counts, Aβ, and tau burden could be obtained for each region. We used linear regression to detect associations between hippocampal atrophy in 3D, clinical diagnosis and total as well as subfield pathology burden measures. As expected, we found significant correlations between hippocampal radial distance and mean neuronal count, as well as diagnosis. There were subfield specific associations between hippocampal radial distance and tau in CA2, and cresyl violet neuronal counts in CA1 and subiculum. These results provide further validation for the European Alzheimer's Disease Consortium Alzheimer's Disease Neuroimaging Initiative Center Harmonized Hippocampal Segmentation Protocol (HarP)

Decline in age at menarche among Spanish women born from 1925 to 1962

<p>Abstract</p> <p>Background</p> <p>While the timing of reproductive events varies across populations, a downward trend in age at menarche has nevertheless been reported in most of the developed world over the past century. Given the impact of change in age at menarche on health conditions, this study sought to examine secular trends in age at menarche among women living in Navarre (Northern Spain) who participated in a population-based breast cancer screening programme.</p> <p>Methods</p> <p>The study was based on 110545 women born from 1925 to 1962. Trends were tested using a linear regression model, in which year of birth was entered continuously as the predictor and age at menarche (years) as the response variable, using size of town and region of birth as covariates.</p> <p>Results</p> <p>Among women born in Navarre between 1925 and 1962, age at menarche declined steadily from an average of 13.72 years in the 1925-1929 birth-cohorts to 12.83 years in the 1958-1962 birth-cohorts. Controlling for size of town or city of birth, age at menarche declined by an average of 0.132 years every 5 years over the period 1925-1962. This decline was greater in women born in rural versus urban settings. Trends were also different among regions of birth.</p> <p>Conclusion</p> <p>We report a population-based study showing a downward trend in age of onset of menarche among Spanish women born in the period 1925-1962, something that is more pronounced among women born in rural settings and varies geographically.</p

Associations between hippocampal morphometry and neuropathologic markers of Alzheimer's disease using 7&nbsp;T MRI.

Hippocampal atrophy, amyloid plaques, and neurofibrillary tangles are established pathologic markers of Alzheimer's disease. We analyzed the temporal lobes of 9 Alzheimer's dementia (AD) and 7 cognitively normal (NC) subjects. Brains were scanned post-mortem at 7&nbsp;Tesla. We extracted hippocampal volumes and radial distances using automated segmentation techniques. Hippocampal slices were stained for amyloid beta (Aβ), tau, and cresyl violet to evaluate neuronal counts. The hippocampal subfields, CA1, CA2, CA3, CA4, and subiculum were manually traced so that the neuronal counts, Aβ, and tau burden could be obtained for each region. We used linear regression to detect associations between hippocampal atrophy in 3D, clinical diagnosis and total as well as subfield pathology burden measures. As expected, we found significant correlations between hippocampal radial distance and mean neuronal count, as well as diagnosis. There were subfield specific associations between hippocampal radial distance and tau in CA2, and cresyl violet neuronal counts in CA1 and subiculum. These results provide further validation for the European Alzheimer's Disease Consortium Alzheimer's Disease Neuroimaging Initiative Center Harmonized Hippocampal Segmentation Protocol (HarP)

Relationship between hippocampal atrophy and neuropathology markers: a 7T MRI validation study of the EADC-ADNI Harmonized Hippocampal Segmentation Protocol

The pathologic validation of European Alzheimer's Disease Consortium Alzheimer's Disease Neuroimaging Initiative Center Harmonized Hippocampal Segmentation Protocol (HarP)