Biomedical subjects

Nancy Pleshko Camacho

Publications and source records attributed to Nancy Pleshko Camacho.

5 recordsLinked to original sources

PubMed2006

FT-IR imaging of native and tissue-engineered bone and cartilage.

Fourier transform infrared (FT-IR) imaging and microspectroscopy have been extensively applied to the analyses of tissues in health and disease. Spatially resolved mid-IR data has provided insights into molecular changes that occur in diseases of connective or collagen-based tissues, including, osteoporosis, osteogenesis imperfecta, osteopetrosis and pathologic calcifications. These techniques have also been used to probe chemical changes associated with load, disuse, and micro-damage in bone, and with degradation and repair in cartilage. This review summarizes the applications of FT-IR microscopy and imaging for analyses of bone and cartilage in healthy and diseased tissues, and illustrates the application of these techniques for the characterization of tissue-engineered bone and cartilage.

Animals↗

PubMed2006

Fourier transform infrared imaging and MR microscopy studies detect compositional and structural changes in cartilage in a rabbit model of osteoarthritis.

Assessment of subtle changes in proteoglycan (PG) and collagen, the primary macromolecular components of cartilage, which is critical for diagnosis of the early stages of osteoarthritis (OA), has so far remained a challenge. In this study we induced osteoarthritic cartilage changes in a rabbit model by ligament transection and medial meniscectomy and monitored disease progression by infrared fiber optic probe (IFOP) spectroscopy, Fourier transform infrared imaging spectroscopy (FT-IRIS), and magnetic resonance imaging (MRI) microscopy. IFOP studies combined with chemometric partial least-squares analysis enabled us to monitor progressive cartilage surface changes from two to twelve weeks post-surgery. FT-IRIS studies of histological sections of femoral condyle cartilage revealed that compared with control cartilage the OA cartilage had significantly reduced PG content 2 and 4 weeks post-surgery, collagen fibril orientation changes 2 and 4 weeks post-surgery, and changes in collagen integrity 2 and 10 weeks post-surgery, but no significant changes in collagen content at any time. MR microscopy studies revealed reduced fixed charge density (FCD), indicative of reduced PG content, in the OA cartilage, compared with controls, 4 weeks post-surgery. A non-significant trend toward higher apparent MT exchange rate, k(m), was also found in the OA cartilage at this time point, suggesting changes in collagen structural features. These two MR findings for FCD and k(m) parallel the FT-IRIS findings of reduced PG content and altered collagen integrity, respectively. MR microscopy studies of the cartilage at the 12-week time point also found a trend toward longer T (2) values and reduced anisotropy in the deep zone of the OA cartilage, consistent with increased hydration and less ordered collagen. These studies reveal that FT-IRIS and MR microscopy provide complementary data on compositional changes in articular cartilage in the early stages of osteoarthritic degradation.

Animals↗

PubMed2006

Fourier transform infrared imaging spectroscopy investigations in the pathogenesis and repair of cartilage.

Significant complications in the management of osteoarthritis (OA) are the inability to identify early cartilage changes during the development of the disease, and the lack of techniques to evaluate the tissue response to therapeutic and tissue engineering interventions. In recent studies several spectroscopic parameters have been elucidated by Fourier transform infrared imaging spectroscopy (FT-IRIS) that enable evaluation of molecular and compositional changes in human cartilage with progressively severe OA, and in repair cartilage from animal models. FT-IRIS permits evaluation of early-stage matrix changes in the primary components of cartilage, collagen and proteoglycan on histological sections at a spatial resolution of approximately 6.25 microm. In osteoarthritic cartilage, the collagen integrity, monitored by the ratio of peak areas at 1338 cm(-1)/Amide II, was found to correspond to the histological Mankin grade, the gold standard scale utilized to evaluate cartilage degeneration. Apparent matrix degradation was observable in the deep zone of cartilage even in the early stages of OA. FT-IRIS studies also found that within the territorial matrix of the cartilage cells (chondrocytes), proteoglycan content increased with progression of cartilage degeneration while the collagen content remained the same, but the collagen integrity decreased. Regenerative (repair) tissue from microfracture treatment of an equine cartilage defect showed significant changes in collagen distribution and loss in proteoglycan content compared to the adjacent normal cartilage, with collagen fibrils demonstrating a random orientation in most of the repair tissue. These studies demonstrate that FT-IRIS is a powerful technique that can provide detailed ultrastructural information on heterogeneous tissues such as diseased cartilage and thus has great potential as a diagnostic modality for cartilage degradation and repair.

Aged↗

PubMed2005

Dental phenotype of the col1a2(oim) mutation: DI is present in both homozygotes and heterozygotes.

Dentinogenesis imperfecta (DI) is a common but variable feature of osteogenesis imperfecta (OI). The Col1a2(oim) mutation (oim) is a well-studied mouse model of chain deficiency OI. Heterozygous oim/+ mice have subtle skeletal fragility, while homozygous oim/oim mice have marked skeletal fragility. To further define the consequences of oim mutation, we examined teeth by light and scanning electron microscopy (SEM). The dental phenotype in Col1a2(oim) (oim) mice is more severe in incisors than in molars and includes changes in pulp chamber size, tooth shape, and dentin ultrastructure. Teeth in oim/oim animals are clinically fragile, while oim/+ teeth are grossly normal. Incisor pulp chamber areas (in mum(2)) are: upper +/+ = 358 +/- 75, lower +/+ = 671 +/- 162, upper oim/+ = 161 +/- 54, lower oim/+ = 156 +/- 19, upper oim/oim = 6900 +/- 1040, and lower oim/oim = 66 +/- 62 (P < 10(-5)). Incisor non-pulp chamber cross-sectional areas (in mum(2)), reflecting dentin areas, are: upper +/+ = 39,000 +/- 1670, lower +/+ = 35,600 +/- 1980, upper oim/+ = 47,500 +/- 2510, lower oim/+ = 26,000 +/- 1830, upper oim/oim = 29,800 + 315, and lower oim/oim = 36,800 +/- 3450 (P < 10(-5)). Ultrastructural abnormalities are more pronounced in incisors than in molars and depend on dosage of the mutant allele. These include reduction in the number and regularity of spacing of the dentinal tubules, lesser mineralization, and blurring of the boundary between peritubular and intertubular dentin. Our findings demonstrate that both oim/oim and oim/+ mice suffer from DI. The more severe incisor phenotype may reflect incisors' continuous growth.

Animals↗

PubMedDate not supplied

Statistical comparison of Fourier transform infrared spectra.

Spectroscopic assessment of whether a biological sample has changed as a result of processing or degradation is generally carried out by qualitative comparison of spectra, without statistical analysis, resulting in a subjective evaluation of sample stability. Here, we present a formalism for quantitative statistical comparison of signal-averaged Fourier transform infrared spectra, commonly used to assess molecular properties of biological samples. Expressions are derived permitting the comparison of 1. single beam spectra; 2. transmittance spectra obtained by calculating the ratio of single beam spectra of a sample and background; and 3. absorbance spectra derived from transmittance spectra. An application of these results to the degradation of cartilage is presented. Two absorbance spectra of a cartilage sample taken in succession are found to be statistically identical with respect to the ratio of the amplitude of the amide I band to the amplitude of the amide II band. However, a spectrum of the same sample acquired after a 24-h degradation period, while similar to the spectrum of the fresh sample, is found to have an altered ratio of these spectral band amplitudes, consistent with degradation of the cartilage matrix.

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