Non-destructive analysis of the protein conformational structure of human pituitary adenomas using reflectance FT-IR microspectroscopy

The pituitary gland under infrared light – in search of a representative spectrum for homogeneous regions

This work focuses on obtaining unique representative FTIR spectrum characteristic for one type of cells architecture. Presented idea is based on using of HCA for data evaluation to search for uniform patterns within samples from the perspective of FTIR spectra.

Infrared microspectroscopy identifies biomolecular changes associated with chronic oxidative stress in mammary epithelium and stroma of breast tissues from healthy young women: implications for latent stages of breast carcinogenesis

Studies of the decades-long latent stages of breast carcinogenesis have been limited to when hyperplastic lesions are already present. Investigations of earlier stages of breast cancer (BC) latency have been stymied by the lack of fiducial biomarkers needed to identify where in histologically normal tissues progression toward a BC might be taking place. Recent evidence suggests that a marker of chronic oxidative stress (OxS), protein adducts of 4-hydroxy-2-nonenal (4HNE), can meet this need. Specifically: (1) 4HNE immunopositive (4HNE+) mammary epithelial (ME) cells were found to be prevalent in normal (reduction mammoplasty) tissues of most women (including many teenagers) studied, representative of those living in the United States' high risk-posing environment and: (2) marked (> 1.5-fold) differences were identified between tissues of healthy young women with many vs. few 4HNE+ ME cells in the relative levels of transcripts for 42 of the 84 OxS-associated genes represented in SABioscience Oxidative-Stress/Oxidative-Defense PCR array. Herein we used synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy to identify molecular changes associated with 4HNE adducts in basal and luminal ME cells in terminal ductal units (TDLU), which are the cells of origin of BC, and associated intralobular and interlobular stroma, known contributors to carcinogenesis. Multivariate analysis-derived wavenumbers differentiated 4HNE+ and 4HNE- cells in each of the anatomical compartments. Specifically, principal component and linear discriminant analyses of mid-infrared spectra obtained from these cells revealed unambiguous, statistically highly significant differences in the "biochemical fingerprint" of 4HNE+ vs. 4HNE- luminal and basal ME cells, as well as between associated intralobular and interlobular stroma. These findings demonstrate further SR-FTIR microspectroscopy's ability to identify molecular changes associated with altered physiological and/or pathophysiological states, in this case with a state of chronic OxS that provides a pro-carcinogenic microenvironment.

Human brain cancer studied by resonance Raman spectroscopy

The resonance Raman (RR) spectra of six types of human brain tissues are examined using a confocal micro-Raman system with 532-nm excitation in vitro. Forty-three RR spectra from seven subjects are investigated. The spectral peaks from malignant meningioma, stage III (cancer), benign meningioma (benign), normal meningeal tissues (normal), glioblastoma multiforme grade IV (cancer), acoustic neuroma (benign), and pituitary adenoma (benign) are analyzed. Using a 532-nm excitation, the resonance-enhanced peak at 1548  cm-1 (amide II) is observed in all of the tissue specimens, but is not observed in the spectra collected using the nonresonance Raman system. An increase in the intensity ratio of 1587 to 1605  cm-1 is observed in the RR spectra collected from meningeal cancer tissue as compared with the spectra collected from the benign and normal meningeal tissue. The peak around 1732  cm-1 attributed to fatty acids (lipids) are diminished in the spectra collected from the meningeal cancer tumors as compared with the spectra from normal and benign tissues. The characteristic band of spectral peaks observed between 2800 and 3100  cm-1 are attributed to the vibrations of methyl (─CH3) and methylene (─CH2─) groups. The ratio of the intensities of the spectral peaks of 2935 to 2880  cm-1 from the meningeal cancer tissues is found to be lower in comparison with that of the spectral peaks from normal, and benign tissues, which may be used as a distinct marker for distinguishing cancerous tissues from normal meningeal tissues. The statistical methods of principal component analysis and the support vector machine are used to analyze the RR spectral data collected from meningeal tissues, yielding a diagnostic sensitivity of 90.9% and specificity of 100% when two principal components are used.

Evaluation of gallbladder lipid level during carcinogenesis by an infrared spectroscopic method

BACKGROUND

Fourier transform infrared (FTIR) spectroscopy is sensitive to the molecular composition of tissue and has the potential to identify premalignant tissue. Our previous studies found that the lipids band of FTIR decreased in malignant tissues compared to normal tissue but increased in the cell line.

AIM

To investigate the change of lipids during carcinogenesis in the gallbladder by FTIR spectroscopy.

METHODS

The tissue from 12 malignant samples and 10 normal samples together with their corresponding tissue plasma membrane and gallbladder cancer cell lines were observed by FTIR.

RESULTS

Specific changes of lipids were observed in the FTIR spectral features of tissue, cell, and plasma membrane. The CH3 stretching band at 2,957 cm(-1) and the CH2 stretching bands at 2,853 cm(-1) decreased in the malignant tissue but increased in the tissue plasma membrane; the C-O stretching band at 1,740 cm(-1) disappeared in the malignant tissue but significantly increased in the tissue plasma membrane. The intensity of these bands all increased in the cancer cell line. The ratio of intensity (I) of 1,460 cm(-1)/1,398 cm(-1) was smaller in malignant tissue and the tissue plasma membrane.

CONCLUSIONS

Lipids were increased in the plasma membrane during carcinogenesis of the gallbladder; the ratio of intensity (I) 1,460 cm(-1)/1,398 cm(-1) could be a marker to diagnose cancer by FTIR.

Classification of malignant gliomas by infrared spectroscopy and linear discriminant analysis

Gliomas are the most frequent primary brain tumors. Their malignancies are graded from 1 to 4. Malignant gliomas are astrocytoma grade 3 and glioblastoma grade 4. An IR spectroscopic approach is presented to diagnose brain tissue at the molecular level probing chemical and structural properties without external markers. IR spectroscopic maps were recorded in transmission mode by sequential acquisition of IR spectra. Training spectra of various tissue types are selected from IR spectroscopic maps in accordance with histological assessment of hematoxylin and eosin stained parallel tissue sections. A decrease of the lipid-to-protein ratio in IR spectra is correlated with the malignancy of gliomas. This chemical property is described by the band intensity ratio 2850 to 1655 cm(-1). Two additional molecular descriptors are identified at 1545 cm(-1)/1655 cm(-1) and (1231 + 1450) cm(-1)/1655 cm(-1), which are associated with hemoglobin and collagen, respectively. This metric is used to train a classification model based on linear discriminant analysis. The model is applied to classify normal brain tissue, astrocytoma grade 2, astrocytoma grade 3, glioblastoma, hemorrhage, and leptomeninges in IR spectroscopic maps of cryosections from two glioma patients. As independent test samples, single IR spectra from cryosections of 51 patients are subjected to the classification model. Normal brain tissue is assigned with 100% accuracy; malignant gliomas are assigned with 93% accuracy. The high success rate demonstrates that IR spectroscopy can complement established methods such as histopathology or immunohistochemistry to characterize dried cryosections.

Fiber-optical and microscopic detection of malignant tissue by use of infrared spectrometry

Several investigations were performed in order to develop an in vivo endoscopic method to differentiate between malignant and healthy tissue working on the assumption that each diseased state of biological tissue has its own characteristic infrared (IR) spectral pattern. The technical design of the laboratory setup is presented here together with the experimental details and the results. Two regions (1245-1195) and (1045-995) cm(-1) within the fingerprint (<1500 cm(-1)) region were selected for analysis. Lead salt diode lasers were used as excitation sources and IR radiation was transmitted via silver halide wave guides to the tissue to be investigated. The IR radiation is returned to a mercury-cadmium-telluride detector by another IR cable. The measurements were carried out in attenuated total reflectance and diffuse reflection/remission. Human colon carcinoma tissue, under humid conditions, was used as a target for experiments to simulate in vivo conditions. Specimens were mapped using a stepper, motor powered, x/y/z-translation stage with a spatial resolution of 1 microm. The results were compared with similar measurements from a Fourier transform IR (FTIR) interferometer/FTIR microscope setup in the wave number region of 4000-900 cm(-1).

Evaluation of glycogen level in human lung carcinoma tissues by an infrared spectroscopic method

Glycogen levels in the tissue samples obtained from carcinomas and normal sections of human lungs (26 patients) were studied by measuring the infrared band intensity at 1045 cm(-1) due to glycogen. As an internal standard peak, the band at 1545 cm(-1) (amide II) was chosen, and the ratios of these band areas (A1045/A1545) were compared with histological classification and differentiation of tumors. The glycogen level in the carcinoma tissues was significantly higher than that in the normal tissues (P < 0.01, n = 26). Further, the ratio of amounts of glycogen in the carcinomas and in the normal tissues for adenocarcinoma was higher than that for squamous cell carcinoma (P < 0.01). The increased degree of differentiation of the squamous cell carcinomas appeared to be correlated with an increase in the glycogen level. These results suggest that comparison of glycogen levels in the tumor and normal section of human lung may be used as a differentiating parameter for abnormality and histological classification of tumors. The present Fourier transform-infrared spectroscopy (FT-IR) method may become of wide application for studying various tissue samples.