Alvin Katz

Fundamental Differences of Excitation Spectrum between Malignant and Benign Breast Tissues

Abstract— Differences observed in the UV excitation spectrum of malignant and benign breast tissues are used to distinguish between malignant and benign breast tissues. These changes are attributed to changes with specialized proteins.

Innate cellular fluorescence reflects alterations in cellular proliferation

The objective of this study was to examine the question of whether unique spectral patterns were associated with cell proliferation and could be identified by comparing the fluorescence pattern of slow to rapid growing cells.

Native fluorescence and excitation spectroscopic changes in Bacillus subtilis and Staphylococcus aureus bacteria subjected to conditions of starvation

Fluorescence emission and excitation spectra were measured over a 7-day period for Bacillus subtilis (Bs), a spore-forming, and Staphylococcus aureus (Sa), a nonspore-forming bacteria subjected to conditions of starvation. Initially, the Bs fluorescence was predominantly due to the amino acid tryptophan. Later, a fluorescence band with an emission peak at 410 nm and excitation peak at 345 m, from dipicolinic acid, appeared. Dipicolinic acid is produced during spore formation and serves as a spectral signature for detection of spores. The intensity of the 410-nm band continued to increase over the next 3 days. The Sa fluorescence was predominantly from tryptophan and did not change over time. In 6 of the 17 Bs specimens studied, an additional band appeared with a weak emission peak at 460 cm and excitation peaks at 250, 270, and 400 nm. The addition of beta-hydroxybutyric acid to the Bs or the Sa cultures resulted in a two-order of magnitude increase in the 460-nm emission. The addition of Fe2+ quenched the 460 emission, indicating that a source of the 460-nm emission was a siderophore produced by the bacteria. We demonstrate that optical spectroscopy-based instrumentation can detect bacterial spores in real time.

In vivo molecular evaluation of guinea pig skin incisions healing after surgical suture and laser tissue welding using Raman spectroscopy.

The healing process in guinea pig skin following surgical incisions was evaluated at the molecular level, in vivo, by the use of Raman spectroscopy. After the incisions were closed either by suturing or by laser tissue welding (LTW), differences in the respective Raman spectra were identified. The study determined that the ratio of the Raman peaks of the amide III (1247 cm(-1)) band to a peak at 1326 cm(-1) (the superposition of elastin and keratin bands) can be used to evaluate the progression of wound healing. Conformational changes in the amide I band (1633-1682 cm(-1)) and spectrum changes in the range of 1450-1520 cm(-1) were observed in LTW and sutured skin. The stages of the healing process of the guinea pig skin following LTW and suturing were evaluated by Raman spectroscopy, using histopathology as the gold standard. LTW skin demonstrated better healing than sutured skin, exhibiting minimal hyperkeratosis, minimal collagen deposition, near-normal surface contour, and minimal loss of dermal appendages. A wavelet decomposition-reconstruction baseline correction algorithm was employed to remove the fluorescence wing from the Raman spectra.

Optical Spectroscopy of Benign and Malignant Breast Tissues

Fluorescence spectroscopy was applied to characterize normal, malignant and adipose breast tissues. Excitation, emission, and synchronized diffusive reflectance spectral scans were measured on over one hundred specimens for the purpose of developing an improved spectroscopic diagnostic technique. These techniques were able to successfully distinguish malignant tissue from adipose glandular fibrous and normal tissue. A sensitivity of 91% for fifty-six (56) malignant specimens with specificity of 91% for forty-six (46) benign tissue specimens has been achieved, using pathology as the golden standard.

Two-photon excitation of fluorescence from chicken tissue

We have measured UV fluorescence excited through two-photon absorption from native chicken tissue, using 600-nm, 500-fs pulses from a R6G dye laser. The observed emission signal was found to depend quadratically on the excitation intensity. The two-photon excitation-induced fluorescence spectrum is attributed to tryptophan residues in proteins.

Detection of glutamate in the eye by Raman spectroscopy

Raman spectroscopy is used to detect glutamate in the eye. Glutamate, a by-product of nerve cell death, is an indicator of glaucoma and diabetic retinopathy. The Raman spectra of ex vivo whole porcine eyes and individual components (lens, cornea, vitreous) are measured and characterized. Monosodium glutamate is injected into the eyes to simulate disease conditions, and the contribution to the Raman spectrum due to the presence of glutamate is identified. The Raman spectra from the native eye is dominated by vibrational modes from proteins in the lens. An optical system is designed to optimize collection of signal from the vitreous, where the glutamate is located, and reduce the Raman from the lens. Two vibrational fingerprints of monosodium glutamate are detected at 1369 and 1422 cm(-1), although the concentrations are much above physiological concentrations.

Near-infrared laser welding of aortic and skin tissues and microscopic investigation of welding efficacy

Ex vivo specimens of human and porcine aorta and skin were welded using either Cr4+:YAG or Erbium fiber lasers tuned to the water absorption band at 1440-1460 nm. Welding was performed without the use of protein solders or glues. Welding efficacy was monitored by measuring the tensile strength of the welded tissue and the extent of collateral tissue damage. Full thickness tissue bonding with no collateral damage was observed with porcine aorta samples. The optimum tensile strength for porcine and human aorta was 1.33 ± 0.15 kg/cm2 and 1.13 ± 0.27 kg/cm2 respectively for welding at 1460 nm, while that for porcine and human skin was 0.94 ± 0.15 kg/cm2 and 1.05 ± 0.19 kg/cm2 respectively achieved with welding at 1455 nm. The weld strength as a function of laser wavelength demonstrated a correlation with the absorption spectrum of native water suggests that absorption of light by water in the tissue plays a significant role in laser tissue welding.

NIR laser tissue welding of in vitro porcine of cornea and sclera tissue

In this study, an NIR fiber laser with an eye safe wavelength of 1.455 μm was used to successfully weld in vitro porcine cornea and sclera tissue. The emission wavelength overlaps an absorption band of water. The laser system was used in combination with a motorized translational system and shutter to control the laser exposure on the tissue being welded. Different welding conditions were analyzed for the porcine cornea and sclera. The welded tissues were examined using histopathology and tensile strength analysis. The NIR welding technique provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. The NIR laser system used in this study can effectively weld cornea and sclera tissue, and this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity.

Ultraviolet-Visible Acousto-Optic Tunable Spectroscopic Imager for Medical Diagnosis

An ultraviolet to visible acousto-optic tunable filter was used to measure native fluorescence images from in vitro breast tissues at different wavelengths. Pseudocolor maps based on fluorescence images at two wavelengths were used to separate normal and abnormal regions in human breast tissues in vitro, providing diagnostic information.