Long-Term Peritoneal Indwelling Catheters for Malignant Ascites: A Retrospective Case Series of PleurX and Peritoneal Port.

Objectives: To compare outcomes of PleurX and peritoneal port for malignant ascites. Design: Retrospective review of medical records was conducted. Setting/Subjects: Subjects were consecutive patients receiving PleurX or peritoneal port for malignant ascites in a center in Sydney, Australia. Measurements: Demographic data, complication rates, hospitalization rates, and survival were measured. Results: Sixteen cases were analyzed: 6 had peritoneal port (170 catheter days) and 10 had PleurX (477 catheter days). Complication rates were low with both drainage systems. Cellulitis rate was 33% (1.2 events/100 catheter days) for peritoneal port and 10% (0.2 events/100 catheter days) for PleurX. Hospital admission days were 27 days/100 catheter days for peritoneal port and 5.2 days/100 catheter days for PleurX. Conclusions: Both PleurX and peritoneal port seem feasible options in draining malignant ascites. Further research is needed to ascertain whether there are true differences in cellulitis/admission rates. Patient quality of life, experience, and preference should be included in future studies.

Establishing CD19 B-cell reference control materials for comparable and quantitative cytometric expression analysis.

In the field of cell-based therapeutics, there is a great need for high-quality, robust, and validated measurements for cell characterization. Flow cytometry has emerged as a critically important platform due to its high-throughput capability and its ability to simultaneously measure multiple parameters in the same sample. However, to assure the confidence in measurement, well characterized biological reference materials are needed for standardizing clinical assays and harmonizing flow cytometric results between laboratories. To date, the lack of adequate reference materials, and the complexity of the cytometer instrumentation have resulted in few standards. This study was designed to evaluate CD19 expression in three potential biological cell reference materials and provide a preliminary assessment of their suitability to support future development of CD19 reference standards. Three commercially available human peripheral blood mononuclear cells (PBMCs) obtained from three different manufacturers were tested. Variables that could potentially contribute to the differences in the CD19 expression, such as PBMCs manufacturing process, number of healthy donors used in manufacturing each PBMC lot, antibody reagent, operators, and experimental days were included in our evaluation. CD19 antibodies bound per cell (ABC) values were measured using two flow cytometry-based quantification schemes with two independent calibration methods, a single point calibration using a CD4 reference cell and QuantiBrite PE bead calibration. Three lots of PBMC from three different manufacturers were obtained. Each lot of PBMC was tested on three different experimental days by three operators using three different lots of unimolar anti-CD19PE conjugates. CD19 ABC values were obtained in parallel on a selected lot of the PBMC samples using mass spectrometry (CyTOF) with two independent calibration methods, EQ4 and bead-based calibration were evaluated with CyTOF-technology. Including all studied variabilities such as PBMC lot, antibody reagent lot, and operator, the averaged mean values of CD19 ABC for the three PBMC manufacturers (A,B, and C) obtained by flow cytometry were found to be: 7953 with a %CV of 9.0 for PBMC-A, 10535 with a %CV of 7.8 for PBMC-B, and 12384 with a %CV of 16 for PBMC-C. These CD19 ABC values agree closely with the findings using CyTOF. The averaged mean values of CD19 ABC for the tested PBMCs is 9295 using flow cytometry-based method and 9699 using CyTOF. The relative contributions from various sources of uncertainty in CD19 ABC values were quantified for the flow cytometry-based measurement scheme. This uncertainty analysis suggests that the number of antigens or ligand binding sites per cell in each PBMC preparation is the largest source of variability. On the other hand, the calibration method does not add significant uncertainty to the expression estimates. Our preliminary assessment showed the suitability of the tested materials to serve as PBMC-based CD19+ reference control materials for use in quantifying relevant B cell markers in B cell lymphoproliferative disorders and immunotherapy. However, users should consider the variabilities resulting from different lots of PBMC and antibody reagent when utilizing cell-based reference materials for quantification purposes and perform bridging studies to ensure harmonization between the results before switching to a new lot.

Misdiagnosis of elevation of ß-hCG in cystic craniopharyngioma: illustrative case.

BACKGROUND: Craniopharyngiomas and germ cell tumors (GCTs) are both rare intracranial tumors commonly present in childhood or middle age. They share similar clinical and radiological features. GCTs commonly give rise to tumor markers in the cerebrospinal fluid, hence guiding the treatment plan. OBSERVATIONS: This article reports the case of a 5-year-old boy with a large sellar and suprasellar mass with obstructive hydrocephalus. Laboratory studies showed increased beta-human chorionic gonadotrophin (ß-hCG) levels in the cystic fluid, suggestive of choriocarcinoma. He underwent 3 cycles of chemotherapy but showed a poor response. Further aspiration followed by tumor debulking was performed, and histopathological examination revealed craniopharyngioma. LESSONS: This case report indicates that ß-hCG, commonly regarded as a specific tumor marker for choriocarcinoma, is detectable in other forms of suprasellar tumors. The authors highlight clinical and radiological features of suprasellar tumors that can be misdiagnosed as intracranial GCTs. The relevance of tumor markers and indications for histopathological confirmation are discussed.

Symptom reduction in palliative care from single session mindful breathing: a randomised controlled trial.

CONTEXT: There has been increasing evidence of the role of mindfulness-based interventions in improving various health conditions. However, the evidence for the use of mindfulness in the palliative care setting is still lacking. OBJECTIVES: The objective of our study was to determine the efficacy of a single session of 20 min mindful breathing in alleviating multiple symptoms in palliative care. METHODS: Adult palliative care in patients with at least one symptom scoring ≥5/10 based on the Edmonton Symptom Assessment Scale (ESAS) were recruited from September 2018 to December 2018. Recruited patients were randomly assigned to either 20 min mindful breathing and standard care or standard care alone. RESULTS: Forty patients were randomly assigned to standard care plus a 20 min mindful breathing session (n=20) or standard care alone (n=20). There was statistically significant reduction of total ESAS score in the mindful breathing group compared with the control group at minute 20 (U=98, n 1 = n 2 = 20, mean rank 1 = 15.4, mean rank 2 = 25.6, median reduction 1 = 6.5, median reduction 2 = 1.5, z=-2.763, r=0.3, p=0.005). CONCLUSION: Our results provided evidence that a single session of 20 min mindful breathing was effective in reducing multiple symptoms rapidly for palliative care patients.

The Effect of 5-Minute Mindfulness of Peace on Suffering and Spiritual Well-Being Among Palliative Care Patients: A Randomized Controlled Study.

BACKGROUND: Mindfulness practices may have a role in reducing suffering and improving spiritual well-being among patients with serious illness. The efficacy, feasibility and acceptability of such interventions warrant further exploration in the palliative care population. OBJECTIVE: To investigate the effect of a brief mindfulness practice, the 5-minute mindfulness of peace intervention, on suffering and spiritual well-being among palliative care patients. METHODS: A randomized controlled study was conducted on adult palliative care patients with moderate to severe levels of suffering. Participants in the intervention arm were guided through a 5-minute mindfulness of peace exercise while participants in the control arm received 5 minutes of active listening. Pre- and post-intervention suffering and spiritual well-being were measured using the Suffering Pictogram and the FACIT-Sp-12 questionnaire, respectively. RESULTS: 40 participants completed the study. 5-minute mindfulness of peace significantly reduced suffering (median = -3.00, IQR = 2.00) more than 5 minutes of active listening (median = -1.00, IQR = 1.75), U = 73.50, z = -3.48, p = 0.001, η2 = 0.31. FACIT-Sp-12 score also significantly improved in the intervention arm (median = +5.00, IQR = 2.75) compared with the control arm after 5 minutes (median = +1.00, IQR = 3.00), U = 95.50, z = -2.85, p = 0.004, η2 = 0.21. CONCLUSIONS: A brief 5-minute mindfulness of peace exercise is effective in providing immediate relief of suffering and improving spiritual well-being. It is a useful and feasible intervention among patients receiving palliative care for rapidly and momentarily reducing spiritual suffering.

Language Mapping in Awake Surgery: Report of Two Cases with Review of Language Networks.

The role of language in communication plays a crucial role in human development and function. In patients who have a surgical lesion at the functional language areas, surgery should be intricately planned to avoid incurring further morbidity. This normally requires extensive functional and anatomical mappings of the brain to identify regions that are involved in language processing and production. In our case report, regions of the brain that are important for language functions were studied before surgery by employing (a) extraoperative methods such as functional magnetic resonance imaging, transmagnetic stimulation, and magnetoencephalography; (b) during the surgery by utilizing intraoperative awake surgical methods such as an intraoperative electrical stimulation; and (c) a two-stage surgery, in which electrical stimulation and first mapping are made thoroughly in the ward before second remapping during surgery. The extraoperative methods before surgery can guide the neurosurgeon to localize the functional language regions and tracts preoperatively. This will be confirmed using single-stage intraoperative electrical brain stimulation during surgery or a two-stage electrical brain stimulation before and during surgery. Here, we describe two cases in whom one has a superficial lesion and another a deep-seated lesion at language-related regions, in which language mapping was done to preserve its function. Additional review on the neuroanatomy of language regions, language network, and its impairment was also described.

Kinetoplastid membrane protein-11 adopts a four-helix bundle fold in DPC micelle.

Kinetoplastid membrane protein-11 (KMP11) is a membrane-associated surface protein of kinetoplastids, which has a strong antigenicity but no mammalian homolog, thus representing a promising vaccine candidate. Here, by CD and NMR, we revealed that in buffer, KMP11 assumes a highly helical conformation without stable tertiary packing. Remarkably, upon interacting with dodecylphosphocholine (DPC) micelle, despite minor changes in secondary structures, KMP11 undergoes rearrangements to form a defined structure. We found that its three-dimensional structure unexpectedly adopts the classic four-helix bundle fold. The surface constituted by the N-/C-termini and conserved loop was characterized to dynamically interact with the polar phase of DPC micelle. Our results provide a structural basis for understanding KMP11 functions and further offer a promising avenue for engineering better vaccines. DATABASE: The structure coordinate of KMP11 in DPC micelle has been deposited in PDB with ID of 5Y70 and the associated NMR data were deposited in BMRB with ID of 36112.

Deep Brain Stimulation (DBS) for Movement Disorders: An Experience in Hospital Universiti Sains Malaysia (HUSM) Involving 12 Patients.

Deep brain stimulation (DBS) was first introduced in 1987 to the developed world. As a developing country Malaysia begun its movement disorder program by doing ablation therapy using the Radionics system. Hospital Universiti Sains Malaysia a rural based teaching hospital had to take into consideration both health economics and outcomes in the area that it was providing neurosurgical care for when it initiated its Deep Brain Stimulation program. Most of the patients were from the low to medium social economic groups and could not afford payment for a DBS implant. We concentrated our DBS services to Parkinson's disease, Tourette's Syndrome and dystonia patients who had exhausted medical therapy. The case series of these patients and their follow-up are presented in this brief communication.

Phospho-Priming Confers Functionally Relevant Specificities for Rad53 Kinase Autophosphorylation.

The vast majority of in vitro structural and functional studies of the activation mechanism of protein kinases use the kinase domain alone. Well-demonstrated effects of regulatory domains or allosteric factors are scarce for serine/threonine kinases. Here we use a site-specifically phosphorylated SCD1-FHA1-kinase three-domain construct of the serine/threonine kinase Rad53 to show the effect of phospho-priming, an in vivo regulatory mechanism, on the autophosphorylation intermediate and specificity. Unphosphorylated Rad53 is a flexible monomer in solution but is captured in an asymmetric enzyme:substrate complex in crystal with the two FHA domains separated from each other. Phospho-priming induces formation of a stable dimer via intermolecular pT-FHA binding in solution. Importantly, autophosphorylation of unprimed and phospho-primed Rad53 produced predominantly inactive pS350-Rad53 and active pT354-Rad53, respectively. The latter mechanism was also demonstrated in vivo. Our results show that, while Rad53 can display active conformations under various conditions, simulation of in vivo regulatory conditions confers functionally relevant autophosphorylation.

A feasibility study of photoacoustic imaging of ex vivo endoscopic mucosal resection tissues from Barrett's esophagus patients.

BACKGROUND AND STUDY AIMS: Accurate endoscopic detection of dysplasia in patients with Barrett's esophagus (BE) remains a major clinical challenge. The current standard is to take multiple biopsies under endoscopic image guidance, but this leaves the majority of the tissue unsampled, leading to significant risk of missing dysplasia. Furthermore, determining whether there is submucosal invasion is essential for proper staging. Hence, there is a clinical need for a rapid in vivo wide-field imaging method to identify dysplasia in BE, with the capability of imaging beyond the mucosal layer. We conducted an ex vivo feasibility study using photoacoustic imaging (PAI) in patients undergoing endoscopic mucosal resection (EMR) for known dysplasia. The objective was to characterize the esophageal microvascular pattern, with the long-term goal of performing in vivo endoscopic PAI for dysplasia detection and therapeutic guidance. MATERIALS AND METHODS:  EMR tissues were mounted luminal side up. The tissues were scanned over a field of view of 14 mm (width) by 15 mm (depth) at 680, 750, and 850 nm (40 MHz acoustic central frequency). Ultrasound and photoacoustic images were simultaneously acquired. Tissues were then sliced and fixed in formalin for histopathology with hematoxylin and eosin staining. A total of 13 EMR specimens from eight patients were included in the analysis, which consisted of co-registration of the photoacoustic images with corresponding pathologist-classified histological images. We conducted mean difference test of the total hemoglobin distribution between tissue classes. RESULTS: Dysplastic and nondysplastic BE can be distinguished from squamous tissue in 84 % of region-of-interest comparisons (42/50). However, the ability of intrinsic PAI to distinguish dysplasia from NDBE, which is the clinically important challenge, was only about 33 % (10/30). CONCLUSION: We demonstrated the technical feasibility of this approach. Based on our ex vivo data, changes in total hemoglobin content from intrinsic PAI (i. e. without exogenous contrast) can differentiate BE from squamous esophageal mucosa. However, most likely intrinsic PAI is unable to differentiate dysplastic from nondysplastic BE with adequate sensitivity for clinical translation.

Can photoacoustic imaging quantify surface-localized J-aggregating nanoparticles?

We investigate the feasibility of photoacoustic (PA) imaging to quantify the concentration of surface-localized nanoparticles, using tissue-mimicking phantoms and imaging with a commercial PA instrument at 815 nm and a linear-array transducer at a center frequency of 40 MHz. The nanoparticles were J-aggregating porphysomes (JNP) comprising self-assembling, all-organic porphyrin-lipid micelles with a molar absorption coefficient of 8.7×108 cm−1 M−1 at this wavelength. The PA signal intensity versus JNP areal concentration followed a sigmoidal curve with a reproducible linear range of ∼17 fmol/mm2 to 11 pmol/mm2, i.e., ∼3 orders of magnitude with ±34% error. For physiologically-relevant conditions (i.e., optical scattering-dominated tissues: transport albedo >0.8) and JNP concentrations above ∼330 fmol/mm2, the PA signal depends only on the nanoparticle concentration. Otherwise, independent measurement of the optical absorption and scattering properties of the underlying tissue is required for accurate quantification. The implications for surface PA imaging, such as in the use of targeted nanoparticles applied topically to tissue as in endoscopic diagnosis, are considered.

Deep Brain Stimulation (DBS) for Movement Disorders: An Experience in Hospital Universiti Sains Malaysia (HUSM) Involving 12 Patients

Deep brain stimulation (DBS) was first introduced in 1987 to the developed world. As a developing country Malaysia begun its movement disorder program by doing ablation therapy using the Radionics system. Hospital Universiti Sains Malaysia a rural based teaching hospital had to take into consideration both health economics and outcomes in the area that it was providing neurosurgical care for when it initiated its Deep Brain Stimulation program. Most of the patients were from the low to medium social economic groups and could not afford payment for a DBS implant. We concentrated our DBS services to Parkinson's disease, Tourette's Syndrome and dystonia patients who had exhausted medical therapy. The case series of these patients and their follow-up are presented in this brief communication.

Controlling Spatial Heat and Light Distribution by Using Photothermal Enhancing Auto-Regulated Liposomes (PEARLs).

Photothermal therapy (PTT) is enhanced by the use of nanoparticles with a large optical absorption at the treatment wavelength. However, this comes at the cost of higher light attenuation that results in reduced depth of heating as well as larger thermal gradients, leading to potential over- and under-treatment in the target tissue. These limitations can be overcome by using photothermal enhancing auto-regulating liposomes (PEARLs), based on thermochromic J-aggregate forming dye-lipid conjugates that reversibly alter their absorption above a predefined lipid phase-transition temperature. Under irradiation by near-infrared light, deeper layers of the target tissue revert to the intrinsic optical absorption, halting the temperature rise and enabling greater light penetration and heat generation at depth. This effect is demonstrated in both nanoparticle solutions and in gel phantoms containing the nanoparticles.

Uncovering the Mechanism of Forkhead-Associated Domain-Mediated TIFA Oligomerization That Plays a Central Role in Immune Responses.

Forkhead-associated (FHA) domain is the only signaling domain that recognizes phosphothreonine (pThr) specifically. TRAF-interacting protein with an FHA domain (TIFA) was shown to be involved in immune responses by binding with TRAF2 and TRAF6. We recently reported that TIFA is a dimer in solution and that, upon stimulation by TNF-α, TIFA is phosphorylated at Thr9, which triggers TIFA oligomerization via pThr9-FHA domain binding and activates nuclear factor κB (NF-κB). However, the structural mechanism for the functionally important TIFA oligomerization remains to be established. While FHA domain-pThr binding is known to mediate protein dimerization, its role in oligomerization has not been demonstrated at the structural level. Here we report the crystal structures of TIFA (residues 1-150, with the unstructured C-terminal tail truncated) and its complex with the N-terminal pThr9 peptide (residues 1-15), which show unique features in the FHA structure (intrinsic dimer and extra ß-strand) and in its interaction with the pThr peptide (with residues preceding rather than following pThr). These structural features support previous and additional functional analyses. Furthermore, the structure of the complex suggests that the pThr9-FHA domain interaction can occur only between different sets of dimers rather than between the two protomers within a dimer, providing the structural mechanism for TIFA oligomerization. Our results uncover the mechanism of FHA domain-mediated oligomerization in a key step of immune responses and expand the paradigm of FHA domain structure and function.

Dynamic principle for designing antagonistic/agonistic molecules for EphA4 receptor, the only known ALS modifier.

Additional to involvement in diverse physiological and pathological processes such as axon regeneration, synaptic plasticity, and cancers, EphA4 receptor has been recently identified as the only amyotrophic lateral sclerosis (ALS) modifier. Previously, we found that two small molecules bind the same EphA4 channel at almost equivalent affinities but mysteriously trigger opposite signaling outputs: one activated but another inhibited. Here, we determined the solution structure of the 181-residue EphA4 LBD, which represents the first for 16 Eph receptors. Further NMR dynamic studies deciphered that the agonistic and antagonistic effects of two small molecules are dynamically driven, which are achieved by oppositely modulating EphA4 dynamics. Consequently, in design of drugs to target EphA4, the dynamic requirement also needs to be satisfied in addition to the classic criteria. For example, to increase the survival of ALS patients by inhibiting EphA4, the drugs must enhance, or at least not suppress, the EphA4 dynamics.

TDP-43 N terminus encodes a novel ubiquitin-like fold and its unfolded form in equilibrium that can be shifted by binding to ssDNA.

Transactivation response element (TAR) DNA-binding protein 43 (TDP-43) is the principal component of ubiquitinated inclusions characteristic of most forms of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia-frontotemporal lobar degeneration with TDP-43-positive inclusions (FTLD-TDP), as well as an increasing spectrum of other neurodegenerative diseases. Previous structural and functional studies on TDP-43 have been mostly focused on its recognized domains. Very recently, however, its extreme N terminus was identified to be a double-edged sword indispensable for both physiology and proteinopathy, but thus far its structure remains unknown due to the severe aggregation. Here as facilitated by our previous discovery that protein aggregation can be significantly minimized by reducing salt concentrations, by circular dichroism and NMR spectroscopy we revealed that the TDP-43 N terminus encodes a well-folded structure in concentration-dependent equilibrium with its unfolded form. Despite previous failure in detecting any sequence homology to ubiquitin, the folded state was determined to adopt a novel ubiquitin-like fold by the CS-Rosetta program with NMR chemical shifts and 78 unambiguous long-range nuclear Overhauser effect (NOE) constraints. Remarkably, this ubiquitin-like fold could bind ssDNA, and the binding shifted the conformational equilibrium toward reducing the unfolded population. To the best of our knowledge, the TDP-43 N terminus represents the first ubiquitin-like fold capable of directly binding nucleic acid. Our results provide a molecular mechanism rationalizing the functional dichotomy of TDP-43 and might also shed light on the formation and dynamics of cellular ribonucleoprotein granules, which have been recently linked to ALS pathogenesis. As a consequence, one therapeutic strategy for TDP-43-causing diseases might be to stabilize its ubiquitin-like fold by ssDNA or designed molecules.

Clinical study of noninvasive in vivo melanoma and nonmelanoma skin cancers using multimodal spectral diagnosis.

The goal of this study was to determine the diagnostic capability of a multimodal spectral diagnosis (SD) for in vivo noninvasive disease diagnosis of melanoma and nonmelanoma skin cancers. We acquired reflectance, fluorescence, and Raman spectra from 137 lesions in 76 patients using custom-built optical fiber-based clinical systems. Biopsies of lesions were classified using standard histopathology as malignant melanoma (MM), nonmelanoma pigmented lesion (PL), basal cell carcinoma (BCC), actinic keratosis (AK), and squamous cell carcinoma (SCC). Spectral data were analyzed using principal component analysis. Using multiple diagnostically relevant principal components, we built leave-one-out logistic regression classifiers. Classification results were compared with histopathology of the lesion. Sensitivity/specificity for classifying MM versus PL (12 versus 17 lesions) was 100%/100%, for SCC and BCC versus AK (57 versus 14 lesions) was 95%/71%, and for AK and SCC and BCC versus normal skin (71 versus 71 lesions) was 90%/85%. The best classification for nonmelanoma skin cancers required multiple modalities; however, the best melanoma classification occurred with Raman spectroscopy alone. The high diagnostic accuracy for classifying both melanoma and nonmelanoma skin cancer lesions demonstrates the potential for SD as a clinical diagnostic device.

How a low-fidelity DNA polymerase chooses non-Watson-Crick from Watson-Crick incorporation.

A dogma for DNA polymerase catalysis is that the enzyme binds DNA first, followed by MgdNTP. This mechanism contributes to the selection of correct dNTP by Watson-Crick base pairing, but it cannot explain how low-fidelity DNA polymerases overcome Watson-Crick base pairing to catalyze non-Watson-Crick dNTP incorporation. DNA polymerase X from the deadly African swine fever virus (Pol X) is a half-sized repair polymerase that catalyzes efficient dG:dGTP incorporation in addition to correct repair. Here we report the use of solution structures of Pol X in the free, binary (Pol X:MgdGTP), and ternary (Pol X:DNA:MgdGTP with dG:dGTP non-Watson-Crick pairing) forms, along with functional analyses, to show that Pol X uses multiple unprecedented strategies to achieve the mutagenic dG:dGTP incorporation. Unlike high fidelity polymerases, Pol X can prebind purine MgdNTP tightly and undergo a specific conformational change in the absence of DNA. The prebound MgdGTP assumes an unusual syn conformation stabilized by partial ring stacking with His115. Upon binding of a gapped DNA, also with a unique mechanism involving primarily helix αE, the prebound syn-dGTP forms a Hoogsteen base pair with the template anti-dG. Interestingly, while Pol X prebinds MgdCTP weakly, the correct dG:dCTP ternary complex is readily formed in the presence of DNA. H115A mutation disrupted MgdGTP binding and dG:dGTP ternary complex formation but not dG:dCTP ternary complex formation. The results demonstrate the first solution structural view of DNA polymerase catalysis, a unique DNA binding mode, and a novel mechanism for non-Watson-Crick incorporation by a low-fidelity DNA polymerase.

α-Glycosylation by D-glucosamine-derived donors: synthesis of heparosan and heparin analogues that interact with mycobacterial heparin-binding hemagglutinin.

Numerous biomolecules possess α-D-glucosamine as structural component. However, chemical glycosylations aimed at this backbone are usually not easily attained without generating the unwanted ß-isomer. We report herein a versatile approach in affording full α-stereoselectivity built upon a carefully selected set of orthogonal protecting groups on a D-glucosaminyl donor. The excellent stereoselectivity provided by the protecting group combination was found independent of leaving groups and activators. With the trichloroacetimidate as the optimum donor leaving group, core skeletons of glycosylphosphatidyl inositol anchors, heparosan, heparan sulfate, and heparin were efficiently assembled. The orthogonal protecting groups were successfully manipulated to further carry out the total syntheses of heparosan tri- and pentasaccharides and heparin di-, tetra-, hexa-, and octasaccharide analogues. Using the heparin analogues, heparin-binding hemagglutinin, a virulence factor of Mycobacterium tuberculosis, was found to bind at least six sugar units with the interaction notably being entropically driven.

Effects of mechanical indentation on diffuse reflectance spectra, light transmission, and intrinsic optical properties in ex vivo porcine skin.

BACKGROUND AND OBJECTIVES: Mechanical indentation has been shown to increase light transmission through turbid tissue. In this study, we investigated the effects of localized indentation on the optical properties of ex vivo porcine skin specimens by dynamically monitoring diffuse reflectance spectra, light transmission, and applied load while controlling tissue thickness. STUDY DESIGN/METHODS: A custom-built diffuse reflectance spectroscopy (DRS) system was used to capture diffuse reflectance spectra from tissue specimens undergoing indentation. The DRS probe was designed to perform both optical sensing and tissue indentation. A mechanical load frame was used to dynamically control probe displacement and resultant specimen thickness change while recording applied load. Diffuse reflectance spectra, as well as light transmission at 630 nm, were recorded during stress relaxation tests where tissue specimens were displaced to and held at a final thickness. Tissue optical properties were extracted from reflectance spectra using a previously established look-up table (LUT) approach. RESULTS: Indentation increased light transmission through tissue during linear displacement, and continued to increase transmission during subsequent stress relaxation at constant tissue thickness. The magnitude of relative transmission increases was shown to be a function of bulk tissue compressive strain (relative thickness change). Reduced scattering coefficients calculated from the LUT at 630 nm decreased during stress relaxation, with the relative decrease in scattering also depending strongly on tissue compressive strain. Reduced scattering coefficients decreased by 12.0 ± 4.7% at 0.44 ± 0.022 compressive strain, and reduced by 35.6 ± 1.3% at 0.71 ± 0.01 compressive strain. CONCLUSION: DRS can be used to capture transient changes in intrinsic tissue optical properties during mechanical loading. Mechanical indentation modifies tissue optical properties and may be harnessed as a minimally-invasive optical clearing technique to improve optical diagnostics and therapeutics.