Discrimination of non-melanoma skin lesions from non-tumor human skin tissues in vivo using Raman spectroscopy and multivariate statistics.

BACKGROUND AND OBJECTIVE: Raman spectroscopy was used to discriminate human non-melanoma skin lesions from non-tumor tissues in vivo. This work proposed the discrimination between non-melanoma (basal cell carcinoma, BCC; squamous cell carcinoma, SCC) and pre-cancerous lesions (actinic keratosis, AK) from benign lesions and normal (non-tumor group, NT) tissues, using near-infrared Raman spectroscopy with a Raman probe. MATERIALS AND METHODS: Prior to surgery, the spectra of suspicious lesions were obtained in situ. The spectra of adjacent, clinically normal skin were also obtained. Lesions were resectioned and submitted for histopathology. The Raman spectra were measured using a Raman spectrometer (830 nm). Two types of discrimination models were developed to distinguish the different histopathological groups. The principal components analysis discriminant analysis (PCA/DA) and the partial least squares discriminant analysis (PLS/DA) were based on Euclidean, quadratic and Mahalanobis distances. RESULTS: PCA and PLS spectral vectors showed spectral features of skin constituents, such as lipids (between 1,250 cm(-1) and 1,300 cm(-1) and at 1,450 cm(-1)) and proteins (between 870 cm(-1) and 940 cm(-1), 1,240 cm(-1) and 1,271 cm(-1), and at 1,000 cm(-1) and 1,450 cm(-1)). Despite the small spectral differences between malignant lesions and benign tissues, the algorithms discriminated the spectra of non-melanoma skin and pre-cancerous lesions from benign and normal tissues, with an overall accuracy of 82.8% and 91.9%, respectively. CONCLUSION: PCA and PLS could discriminate Raman spectra of skin tissues, opening the way for an in vivo optical diagnosis.

Safflower oil: an integrated assessment of phytochemistry, antiulcerogenic activity, and rodent and environmental toxicity

Gastric ulcers are a significant medical problem and the development of complications lead to significant mortality rates worldwide. In Brazil, Carthamus tinctorius L., Asteraceae, seeds essential oil, the safflower oil, is currently used as a thermogenic compound and as treatment for problems related to the cardiovascular system. In this study, by Raman spectroscopy, it was shown that oleic and linoleic acids are the compounds present in higher concentrations in the safflower oil. We demonstrated that safflower oil (750 mg/kg, p.o.) decrease the ulcerogenic lesions in mice after the administration of hydrochloric acid-ethanol. The gastric ulcers induced by non-steroidal anti-inflammatory drug (NSAID) in mice treated with cholinomimetics were treated with four different doses of safflower oil, of which, the dose of 187.5 mg/kg (p.o.) showed significant antiulcerogenic properties (**p < 0.01). Moreover, the safflower oil at doses of 187.5 mg/kg (i.d.) increased the pH levels, gastric volume (**p < 0.01) and gastric mucus production (***p < 0.001), and decreased the total gastric acid secretion (***p < 0.001). The acute toxicity tests showed that safflower oil (5.000 mg/kg, p.o.) had no effect on mortality or any other physiological parameter. Ecotoxicological tests performed using Daphnia similis showed an EC50 at 223.17 mg/l, and therefore safflower oil can be considered “non-toxic” based on the directive 93/67/EEC on risk assessment for new notified substances by European legislation. These results indicate that the antiulcer activity of Safflower oil may be due to cytoprotective effects, which serve as support for new scientific studies related to this pathology.

Raman spectroscopy validation of DIAGNOdent-assisted fluorescence readings on tibial fractures treated with laser phototherapy, BMPs, guided bone regeneration, and miniplates.

OBJECTIVES: We aimed to assess through Raman spectroscopy and fluorescence the levels of calcium hydroxyapatite (CHA) and lipids and proteins in complete fractures treated with internal rigid fixation (IRF) treated or not with laser phototherapy (LPT) and associated or not with bone morphogenetic proteins (BMPs) and guided bone regeneration (GBR). BACKGROUND: Fractures have different etiologies and treatments and may be associated with bone losses. LPT has been shown to improve bone healing. METHODS: Tibial fractures were created on 15 animals and divided into five groups. LPT started immediately after surgery, repeated at 48-h intervals. Animal death occurred after 30 days. RESULTS: Raman spectroscopy and fluorescence were performed at the surface. Fluorescence data of group IRF + LPT + Biomaterial showed similar readings to those of the group IRF-no bone loss. Significant differences were seen between groups IRF + LPT + Biomaterial and IRF + LPT; IRF + LPT + Biomaterial; and IRF + Biomaterial; and between IRF + LPT + Biomaterial and IRF. CH groups of lipids and proteins readings showed decreased levels of organic components in subjects treated with the association of LPT, biomaterial, and GBR. Pearson correlation showed that fluorescence readings of both CHA and CH groups of lipids and proteins correlated negatively with the Raman data. CONCLUSIONS: The use of both methods indicates that the use of the biomaterials associated with infrared LPT resulted in a more-advanced and higher quality of bone repair in fractures treated with miniplates and that the DIAGNOdent may be used to perform optical biopsy on bone.

Effects of laser photherapy on bone defects grafted with mineral trioxide aggregate, bone morphogenetic proteins, and guided bone regeneration: a Raman spectroscopic study.

We have used Raman analysis to assess bone healing on different models. Benefits on the isolated or combined use of mineral trioxide aggregate, bone morphogenetic proteins, guided bone regeneration and laser on bone repair have been reported, but not their combination. We studied peaks of hydroxyapatite and CH groups on defects grafted with MTA, treated or not with laser, BMPs, and GBR. Ninety rats were divided in 10 groups each, subdivided into three subgroups. Laser (λ850 nm) was applied at every other day for 2 weeks. Raman readings were taken at the surface of the defect. Statistical analysis (CHA) showed significant differences between all groups (p = 0.001) and between Group II and all other (p < 0.001), but not with Group X (p = 0.09). At day 21 differences were seen between all groups (p = 0.031) and between Groups VIII and X when compared with Groups VI (p = 0.03), V (p < 0.001), IV (p < 0.001), and IX (p = 0.04). At the end of the experimental period no significant differences were seen. On regards CH, significant differences were seen at the 15(th) day (p = 0.002) and between Group II and all other groups (p < 0.0001) but not with control. Advanced maturation on irradiated bone is because of increased secretion of calcium hydroxyapatite (CHA) that is indicative of greater calcification and resistance of the bone. We conclude that the association of the MTA with laser phototherapy (LPT) and/or not with GBR resulted in a better bone repair. The use of the MTA associated to IR LPT resulted in a more advanced and quality bone repair.

The effect of the association of near infrared laser therapy, bone morphogenetic proteins, and guided bone regeneration on tibial fractures treated with internal rigid fixation: a Raman spectroscopic study.

Fractures have different etiology and treatment and may be associated or not to bone losses. Laser light has been shown to improve bone healing. We aimed to assess, through Raman spectroscopy, the level of CHA (approximately 958 cm(-1)) on complete fractures animals treated with IRF treated or not with Low Level Laser Therapy-LLLT and associated or not to BMPs and GBR. Complete tibial fractures were created on 15 animals that were divided into five groups. LLLT (Laser Unit, Kondortech, São Carlos, SP, Brazil, lambda790 nm, 4 J/cm(2)/point, 40 mW, phi approximately 0.5 cm(2), 16 J/cm(2) session) started immediately after surgery and repeated at 48 h interval (2 weeks). Animal death occurred after 30 days. Raman spectroscopy was performed at the surface of the fracture. Our results showed significant differences between the groups IRF + BL /IRF_NBL (p = 0.05); between all experimental groups and untreated bone; bone/IRF + BL; IRF + BL + Bio + GBR; IRF + BL + LLLT; IRF + BL + Bio + GBR + LLLT; IRF_NBL (p < 0.001, all); IRF_NBL/IRF + BL + LLLT (p = 0.03); IRF_NBL/IRF + BL + Bio + GBR + LLLT (p = 0.02); IRF + BL/IRF + BL + LLLT (p = 0.04); IRF + BL/IRF + BL + Bio + GBR + LLLT (p = 0.002); IRF + BL + Bio + GBR/IRF + BL + Bio + GBR + LLLT (p = 0.05). It is concluded that the use of NIR LLLT associated to BMPs and GBR was effective in improving bone healing on fractured bones due to increased levels of CHA.

Near-infrared Raman spectroscopy to detect anti-Toxoplasma gondii antibody in blood sera of domestic cats: quantitative analysis based on partial least-squares multivariate statistics.

Toxoplasmosis is an important zoonosis in public health because domestic cats are the main agents responsible for the transmission of this disease in Brazil. We investigate a method for diagnosing toxoplasmosis based on Raman spectroscopy. Dispersive near-infrared Raman spectra are used to quantify anti-Toxoplasma gondii (IgG) antibodies in blood sera from domestic cats. An 830-nm laser is used for sample excitation, and a dispersive spectrometer is used to detect the Raman scattering. A serological test is performed in all serum samples by the enzyme-linked immunosorbent assay (ELISA) for validation. Raman spectra are taken from 59 blood serum samples and a quantification model is implemented based on partial least squares (PLS) to quantify the sample's serology by Raman spectra compared to the results provided by the ELISA test. Based on the serological values provided by the Raman/PLS model, diagnostic parameters such as sensitivity, specificity, accuracy, positive prediction values, and negative prediction values are calculated to discriminate negative from positive samples, obtaining 100, 80, 90, 83.3, and 100%, respectively. Raman spectroscopy, associated with the PLS, is promising as a serological assay for toxoplasmosis, enabling fast and sensitive diagnosis.

Exercise order interacts with rest interval during upper-body resistance exercise.

The purpose of this study was to compare repetition performance when resting 1 minute vs. 3 minutes between sets and exercises for an upper-body workout performed in 2 different sequences. Sixteen recreationally trained men completed 4 experimental resistance exercise sessions. All sessions consisted of 3 sets with an 8-repetition maximum load for 6 upper-body exercises. Two different exercise sequences (i.e., A or B) were performed with either 1- or 3-minute rest between sets and exercises, respectively. For sequence A1 (SEQA1) and sequence A3 (SEQA3), resistance exercises were performed in the following order: lat pull-down with a wide grip (LPD-WG), lat pull-down with a close grip (LPD-CG), machine seated row (SR-M), barbell row lying on a bench (BR-B), dumbbell seated arm curl (SAC-DB), and machine seated arm curl (SAC-M). Conversely, for sequence B1 (SEQB1) and sequence B3 (SEQB3), the exercises were performed in the opposite order. The results demonstrated that the effect of exercise order was stronger than the effect of rest interval length for LPD-WG (SEQA3>SEQA1>SEQB3>SEQB1) and SAC-M (SEQB3>SEQB1>SEQA3>SEQA1), whereas the effect of rest interval length was stronger than the effect of exercise order for LPD-CG, SR-M, SAC-DB (SEQA3=SEQB3>SEQA1=SEQB1), and BR-B (SEQB3>SEQA3=SEQB1>SEQA1). These results suggest that upper-body exercises involving similar muscle groups and neural recruitment patterns are negatively affected in terms of repetition performance when performed at the end vs. the beginning of a session, and the reduction in repetition performance is greater when using 1-minute vs. 3-minute rest interval between sets.

Catheters: instrumental advancements in biomedical applications of optical fibers.

This review is focused on the advancements in biomedical engineering regarding the elaboration of new prototypes of optical fiber catheters to be applied in spectroscopic analysis, such as Raman and fluorescence spectroscopy. Our group has contributed to the development of new prototypes with interesting properties, such as side-viewing signal excitation and collection, distal tip with bending control, and Raman scattering minimization from the optical fiber. In addition, several groups have contributed to other new catheter-improving properties of this spectroscopic device. However, a relatively small number of studies has been published in the literature, due to industrial interest in this interdisciplinary and multidisciplinary area. To our knowledge, no review that has focused on the applications of catheters to several modes of spectroscopy has been published. In this work we revised this topic, analyzing the advancements and limitations of the recent biomedical catheters.

The effects of low-level light emitting diode on the repair process of Achilles tendon therapy in rats.

Thirty Wistar rats (350 +/- 20 g) were subjected to total Achilles tendon tenotomy of the right fore limb. They were submitted to a daily dose of 20 J/cm(2) light emitting diode (LED) (640 +/- 20 nm) therapy. The LED was applied punctually and transcutaneously to the lesioned region. The animals were separated into six groups, C1 and L1, C2 and L2, C3 and L3. The C groups were used for control and the L groups, treated for 7, 14 and 21 consecutive days, respectively. The animals were killed on the 7th, 14th and 21st days after surgery. After the animals had been killed, their tendons were extracted and dissected, fixed in formaldehyde at 10%, and sent for histological analysis by light microscopy in which the repair process was analysed. This study demonstrated that LED interfered in the repair process of the tendon tissue, reducing the number of fibroblasts in the initial periods and improving the quality of the repair in all periods studied.

Electromyographic Study of a Sequence of Yau-Man Kung Fu Palm Strikes with and without Impact.

IN MARTIAL ARTS AND CONTACT SPORTS, STRIKES ARE OFTEN TRAINED IN TWO DIFFERENT WAYS: with and without impacts. This study aims to compare the electromyographical activity (EMG) of the triceps brachii (TB), biceps brachii (BB) and brachioradialis (BR) muscles during strikes with and without impacts. Eight Yau-Man Kung Fu practitioners participated in the experiment. Each participant performed 5 sequences of 5 consecutive KF Yau-Man palm strikes with no impact intercalated with 5 sequences of 5 repetitions targeting a KF training shield. Surface EMG signals were obtained from the TB, BB, and RB for 3.0 seconds using an eight-channel module with a total amplifier gain of 2000 and sampled at 3500 Hz. The EMG analyses were done in the time (rms) and frequency (wavelet) domains. For the frequency domain, Morlet wavelet power spectra were obtained and an original method was used to quantify statistically significant regions on the power spectra. The results both in the time and frequency domains indicate a higher TB and BR muscle activity for the strikes with impacts. No significant difference was found for the BB in the two different scenarios. In addition, the results show that the wavelet power spectra pattern for the three analysed muscles obtained from the strikes with and without impacts were similar. Key pointsEMG analysis of a sequence of Kung Fu strikes demonstrates higher Triceps Brachii and Brachioradialis muscle activity for strikes with impact than strikes without impact.An original reliable method for quantifying EMG wavelet transform results is presented.EMG wavelet power spectra describe muscle roles during a Kung Fu sequence of strikes.

Raman spectroscopy study of atherosclerosis in human carotid artery.

Fourier-transform (FT)-Raman spectroscopy has been used for identification and evaluation of human artherosclerotic lesions, providing biochemical information on arteries. In this work, fragments of human carotid arteries postmortem were analyzed using a FT-Raman spectrometer operating at an excitation wavelength of 1064 nm, power of 200 mW, and spectral resolution of 4 cm(-1). A total of 75 carotid fragments were spectroscopically scanned and FT-Raman results were compared with histopathology. Discriminant analysis using Mahalanobis distance was applied over principal components scores for tissue classification into three categories: nonatherosclerotic, atherosclerotic plaque without calcification and with calcification. Nonatherosclerotic artery, atherosclerotic plaque, and calcified plaque exhibit spectral signatures related to biochemicals presented in each tissue type, such as bands of collagen and elastin (proteins), cholesterol and its esters, and calcium hydroxyapatite and carbonate apatite, respectively. Spectra of nonatherosclerotic artery were then classified into two groups: normal and discrete diffuse thickening of the intima layer (first group) and moderate and intense diffuse thickening of the intima layer (second group). FT-Raman could identify and classify the tissues found in the atherosclerotic process in human carotid in vitro and had the ability to identify alterations to the diffuse thickening of the intima layer and classify it depending on the intensity of the thickening.

Resposta in vitro de células gliossarcoma 9L após terapia fotodinâmica utilizando imagem de bioluminescência / In vitro gliosarcoma 9L cells response after photodynamic therapy using bioluminescence imaging

Objetivos: O presente estudo tem o objetivo de demonstrar os resultados iniciais da utilização da técnica deimagem de bioluminescência como método de monitoramento do tratamento de células de gliossarcoma de rato 9L após Terapia Fotodinâmica (TFD) utilizando o ácido aminolevulínico (ALA) como agente fotossensibilizante. Métodos: Para o presente estudo, células 9L foram transfectadas com um plasmídeo contendo o gene da luciferase, permitindo que essa linhagem celular produzisse a proteína luciferase, um dos substratos necessários para a reação de bioluminescência. No presente estudo, a TFD foi realizada utilizando diferentes doses de luz e de ácido aminolevulínico. Para validar a técnica de imagem de bioluminescência como método para o monitoramento da resposta de células tumorais e para a verificação da correlação entre o sinal luminoso e o grau de morte celular após TFD, foi utilizado o ensaio de viabilidade celular com Sulforodamina B (SRB). Resultados: Os resultados destetrabalho mostram alta correlação entre o número de células e o sinal de bioluminescência (R2 = 0,996). Os ensaios de viabilidade celular utilizando a técnica SRB, mostraram excelente correlação entre o número relativo de células sobreviventes após TFD e o sinal de bioluminescência, mostrando que a técnica de imagem de bioluminescência pode ser utilizada para o monitoramento da resposta tumoral após o tratamento de células tumorais com TFD. Os resultados do tratamento das células com terapia fotodinâmica mostram que a taxa de indução de morte celular varia de acordo com a dose de luz e fotossensibilizante empregada durante o tratamento. Nesse sentido, doses maiores de TFD resultaram em níveis mais elevados de indução de morte celular, com efeitos mais prolongados observados através do sinal bioluminescente decorridos 48 horas após a TFD. Conclusão: Este estudo demonstra que a técnica de imagem de bioluminescência pode ser utilizada para o estudo dos efeitos da terapia fotodinâmica em células tumorais. Trabalhos em animais estão em andamento no presente momento para validar a técnica de imagem de bioluminescência após TFD in vivo.

Vicker's hardness and Raman spectroscopy evaluation of a dental composite cured by an argon laser and a halogen lamp.

We present the results of the Vicker's hardness test and the use of near-infrared Raman spectroscopy (RS) to measure in vitro the degree of conversion (DC) of a bis(phenol)-A-glycidyl-dimethacrylate-based composite resin, photoactivated by both a halogen lamp (power density=478 mW/cm(2); 8-mm diameter spot) and an argon laser (power density=625 mW/cm(2); 7-mm diameter spot). The degree of conversion was estimated by analyzing the relative intensities between the aromatic C=C stretching Raman mode at 1610 cm(-1) and the methacrylate C=C stretching Raman mode (1640 cm(-1)) on top and bottom surfaces. For the hardness evaluation, the samples were embedded in polyester resin and three indentations with a 50-g load for 10 s were made on the top surface. The higher relative DC values achieved by the photoactivation of a composite resin by the argon laser suggest a better biocompatibility in the bottom surface. The correlation test showed that the higher Vicker's hardness number (VHN) values were associated with higher DC values. The derivative analysis showed a greater curing rate from 5 to 20 s of exposure. The comparison of VHN and DC values with both light sources at each curing time showed that a small change in conversion is related to a large change in hardness. Raman spectroscopy is more sensitive to changes in the first stages of curing reaction than later ones, and the Vicker's hardness assay is more sensitive to changes in the last stages.

Dose and wavelength of laser light have influence on the repair of cutaneous wounds.

OBJECTIVE: The objective of the present study was to compare histologically the effect of GaAlAs (lambda 830 nm, phi approximately 2 mm(2), 35 mW) and InGaAlP (lambda 685 nm, phi approximately 2 mm(2), 35 mW) lasers, alone or in association with doses of 20 or 50 J/cm(2) on cutaneous wounds in the dorsum of the Wistar rat. BACKGROUND DATA: The healing time of surgical wounds is of extreme importance and it is usually associated with a post-operative period free of infection and with less pain and inflammation. MATERIALS AND METHODS: Sixty Wistar rats were divided into seven groups: Group I - control (non-irradiated); Group II - lambda 685 nm, 20 J/cm(2); Group III - lambda 830 nm, 20 J/cm(2); Group IV - lambda 685 nm and lambda 830 nm, 20 J/cm(2); Group V - lambda 685 nm, 50 J/cm(2)); Group VI - lambda 830 nm, 50 J/cm(2); and Group VII - lambda 685 nm and 830 nm, 50 J/cm(2). The animals were sacrificed 3, 5, and 7 days after surgery. RESULTS: Light microscopic analysis using H&E and Picrosírius stains showed that, at the end of the experimental period, irradiated subjects showed increased collagen production and organization when compared to non-irradiated controls. Inflammation was still present in all groups at this time. CONCLUSION: Group IV (lambda 830 nm and lambda 685 nm, 20 J/cm(2)) presented better results at the end of the experimental period. It is concluded that low-level light therapy (LLLT) can have a positive biomodulatory effect on the repair of cutaneous wounds.

Dentin evaluation after Nd:YAG laser irradiation using short and long pulses.

OBJECTIVE: Several reports have demonstrated the advantages of using the Nd:YAG laser to reduce dentin permeability by melting the dentin surface. A comparative study using different pulse durations can be useful to obtain further information about the laser-hard tissue interaction. MATERIALS AND METHODS: The present study pursues the evaluation of the morphological and chemical changes in human dentin surface resulting from Nd:YAG laser (lambda = 1064 nm) irradiation, with a total energy of 0.9 J distributed in 1, 2, 3, and 6 pulses with different pulse durations to promote surface melting and dentinal tubule occlusion. After irradiation, the samples were submitted to scanning electron microscopy (SEM) analysis for morphological study and energy-dispersive spectrometry (EDS) analysis for evaluation of the concentration of calcium and phosphorous in the melted layer. RESULTS: SEM analysis of the irradiated dentin surface showed surface structural changes due to laser irradiation, where the morphological changes are dependent on the laser pulse duration. EDS analysis showed an increase of calcium and phosphorous concentrations after Nd:YAG laser exposure, but no correlation with the number of pulses or pulse duration was found. CONCLUSION: Our results suggest that longer interaction times resulted in more evident effects with more melted substrate than shorter pulses, and in both cases the resultant melted layer contains a greater concentration of inorganic substances than non-irradiated dentin.

Effect of low-power GaAlAs laser (660 nm) on bone structure and cell activity: an experimental animal study.

Low-level laser therapy (LLLT) is increasingly being used in the regeneration of soft tissue. In the regeneration of hard tissue, it has already been shown that the biomodulation effect of lasers repairs bones more quickly. We studied the activity in bone cells after LLLT close to the site of the bone injury. The femurs of 48 rats were perforated (24 in the irradiated group and 24 in the control group) and the irradiated group was treated with a GaAlAs laser of 660 nm, 10 J/cm2 of radiant exposure on the 2nd, 4th, 6th and 8th days after surgery (DAS). We carried out histomorphometry analysis of the bone. We found that activity was higher in the irradiated group than in the control group: (a) bone volume at 5 DAS (p=0.035); (b) osteoblast surface at 15 DAS (p=0.0002); (c) mineral apposition rate at 15 and 25 DAS (p=0.0008 and 0.006); (d) osteoclast surface at 5 DAS and 25 DAS (p=0.049 and p=0.0028); and (e) eroded surface ( p=0.0032). We concluded that LLLT increases the activity in bone cells (resorption and formation) around the site of the repair without changing the bone structure.

Optothermal transfer simulation in laser-irradiated human dentin.

Laser technology has been studied as a potential replacement to the conventional dental drill. However, to prevent pulpal cell damage, information related to the safety parameters using high-power lasers in oral mineralized tissues is needed. In this study, the heat distribution profiles at the surface and subsurface regions of human dentine samples irradiated with a Nd:YAG laser were simulated using Crank-Nicolson's finite difference method for different laser energies and pulse durations. Heat distribution throughout the dentin layer, from the external dentin surface to the pulp chamber wall, were calculated in each case, to investigate the details of pulsed laser-hard dental tissue interactions. The results showed that the final temperature at the pulp chamber wall and at the dentin surface are strongly dependent on the pulse duration, exposure time, and the energy contained in each pulse.

Use of near-infrared raman spectroscopy to detect IgG and IgM antibodies against Toxoplasma gondii in serum samples of domestic cats.

Near-infrared Raman spectroscopy (NIRS) is a particularly promising technique that is being used in recent years formany biomedical applications. Optical spectroscopy has gained increasing prominence as a tool for quantitative analysis of biological samples, clinical diagnostic, concentration measurements of blood metabolites and therapeutic drugs, and analysis of the chemical composition of human tissues. Toxoplasmosis is an important zoonosis in public health, and domestic cats are the most important transmitters of the disease. This disease can be detected by several serological tests, which usually have a high cost and require a long time. The goal of this work was to investigate a new method to diagnosis Toxoplasma gondii infections using NIRS. In order to confirm antibody detection, 24 cat blood serum samples were analyzed by the Raman spectra, from which 23 presented positive serology to toxoplasmosis and one was a reference negative serum. Characteristic Raman peaks allowed differentiation between negative and positive sera, confirming the possibility of antibody detection by Raman spectroscopy. These results give the first evidence that this technique can be useful to quantify antibodies in cat sera.

Correlation between near-infrared Raman spectroscopy and the histopathological analysis of atherosclerosis in human coronary arteries.

BACKGROUND AND OBJECTIVES: Modern diagnostic methods such as near-infrared Raman spectroscopy (NIRS) allow quantification and evaluation of human atherosclerotic lesions, which can be useful in diagnosing coronary artery disease. The objective of the present study is to obtain feasible diagnostic information to detect atheromatous plaque using NIRS combined with discriminant analysis. STUDY DESIGN/MATERIAL AND METHODS: An 830 nm Ti: sapphire laser pumped by an argon laser provides near-infrared excitation. A spectrograph disperses light scattered from arterial tissue and a liquid-nitrogen cooled CCD detects the Raman spectra. A total of 111 arterial fragments were scanned and Raman results were compared with histopathology. Principal components analysis (PCA) and Mahalanobis distance (m-distance) were used to model an algorithm for tissue classification into three categories: non-atherosclerotic (NA), non-calcified (NC), and calcified (C) using Raman spectra. Spectra were randomly separated into training and prospective groups. RESULTS: It has been found that, for the NA tissue, the algorithm has sensitivity of 84 and 78% and specificity of 91 and 93% for training and prospective groups, respectively. For the NC tissue the algorithm has sensitivity of 88 and 90% and specificity of 88 and 83%. For the C tissue both sensitivity and specificity were maximum, 100%. CONCLUSIONS: An algorithm using PCA and discriminant analysis based on m-distance has been developed and successfully applied to diagnose coronary artery disease by NIRS obtaining good sensitivity and specificity for each tissue category.