Safety Issues of Herb-Warfarin Interactions

Warfarin is a popular anticoagulant with high global demand. However, studies have underlined serious safety issues when warfarin is consumed concomitantly with herbs or its formulations. This review aimed to highlight the mechanisms behind herb-warfarin interactions while laying special emphasis on its PKPD interactions and evidence on Herb-Warfarin Interaction (HWI) with regards to three different scenarios, such as when warfarin is consumed with herbs taken as foods or prescribed as medicine, or when used in special situations. A targeted literature methodology involving different scientific databases was adopted for acquiring information on the subject of HWIs. Results of the present study revealed some of the fatal consequences of HWI, including post-operative bleeding, thrombosis, subarachnoid hemorrhage, and subdural hematomas occurring as a result of interactions between warfarin and herbs or commonly associated food products from Hypericum perforatum, Zingiber officinale, Vaccinium oxycoccos, Citrus paradisi, and Punica granatum. In terms of PK-PD parameters, herbs, such as Coptis chinensis Franch. and Phellodendron amurense Rupr., were found to compete with warfarin for binding with plasma proteins, leading to an increase in free warfarin levels in the bloodstream, resulting in its augmented antithrombic effect. Besides, HWIs were also found to decrease International Normalised Ratio (INR) levels following the consumption of Persea americana or avocado. Therefore, there is an urgent need for an up-to-date interaction database to educate patients and healthcare providers on these interactions, besides promoting the adoption of novel technologies, such as natural language processing, by healthcare professionals to guide them in making informed decisions to avoid HWIs.

Is Tinospora cordifolia Responsible for Drug-induced Liver Injury?

A number of journal articles written by researchers claiming Tinospora cordifolia (Giloy) is to blame for liver damage have sparked a wide range of debates between Ayush and the allopathic medical community, particularly in India. Some even argue that promoting Giloy-based formulations to the general public is a bad idea. In this backdrop, the purpose of this essay is to provide a counter-narrative based on some of the major gaps in the research that implicated Giloy in Drug-induced Liver Injury (DILI). Time-tested herb, Giloy, which has been used for pharmacological benefits since antiquity, as well as clinical and toxicological evidence suggest that Giloy is safe, and the observed negative effects can be attributed to Tinospora crispa, a herb that resembles Tinospora cordifolia in appearance. Holding Giloy species to be detrimental is unjustifiable unless other variables such as authentication, standardization, Good Agricultural and Collection Practices (GACP), Good Manufacturing Practices (GMP), regularization of the market are considered. This article emphasizes the importance of strategic collaboration between plants and contemporary medicine in order to eliminate concerns about the use of Giloy by the general public.

Delivery of gene editing therapeutics

For the past decades, gene editing demonstrated the potential to attenuate each of the root causes of genetic, infectious, immune, cancerous, and degenerative disorders. More recently, Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated protein 9 (CRISPR-Cas9) editing proved effective for editing genomic, cancerous, or microbial DNA to limit disease onset or spread. However, the strategies to deliver CRISPR-Cas9 cargos and elicit protective immune responses requires safe delivery to disease targeted cells and tissues. While viral vector-based systems and viral particles demonstrate high efficiency and stable transgene expression, each are limited in their packaging capacities and secondary untoward immune responses. In contrast, the nonviral vector lipid nanoparticles were successfully used for as vaccine and therapeutic deliverables. Herein, we highlight each available gene delivery systems for treating and preventing a broad range of infectious, inflammatory, genetic, and degenerative diseases. STATEMENT OF SIGNIFICANCE: CRISPR-Cas9 gene editing for disease treatment and prevention is an emerging field that can change the outcome of many chronic debilitating disorders.

Role of Nanoparticle-Conjugates and Nanotheranostics in Abrogating Oxidative Stress and Ameliorating Neuroinflammation

Oxidative stress is a deteriorating condition that arises due to an imbalance between the reactive oxygen species and the antioxidant system or defense of the body. The key reasons for the development of such conditions are malfunctioning of various cell organelles, such as mitochondria, endoplasmic reticulum, and Golgi complex, as well as physical and mental disturbances. The nervous system has a relatively high utilization of oxygen, thus making it particularly vulnerable to oxidative stress, which eventually leads to neuronal atrophy and death. This advances the development of neuroinflammation and neurodegeneration-associated disorders such as Alzheimer's disease, Parkinson's disease, epilepsy, dementia, and other memory disorders. It is imperative to treat such conditions as early as possible before they worsen and progress to irreversible damage. Oxidative damage can be negated by two mechanisms: improving the cellular defense system or providing exogenous antioxidants. Natural antioxidants can normally handle such oxidative stress, but they have limited efficacy. The valuable features of nanoparticles and/or nanomaterials, in combination with antioxidant features, offer innovative nanotheranostic tools as potential therapeutic modalities. Hence, this review aims to represent novel therapeutic approaches like utilizing nanoparticles with antioxidant properties and nanotheranostics as delivery systems for potential therapeutic applications in various neuroinflammation- and neurodegeneration-associated disease conditions.

Why Pharmacovigilance of Non-steroidal Anti-inflammatory Drugs is Important in India?

BACKGROUND

Non-steroidal Anti-Inflammatory Drugs (NSAIDs) are among the drugs that are most regularly administered to manage inflammation and pain. Over-the-Counter (OTC) NSAIDs are widely accessible, particularly in developing countries like India. This casual approach to using NSAIDs may operate as a magnet for NSAID-related adverse drug reactions (ADRs) among patients.

OBJECTIVES

As patients in India are less informed about the appropriate use of NSAIDs and consumption patttern, adverse drug reactions, and the importance of reporting ADRs, the current study's objective is to promote patient safety by using pharmacovigilance as a tool to educate patients.

METHODS

A targeted literature methodology was utilized to gather the data pertaining to NSAIDs, their ADRs and their pharmacovigilance. Different scientific databases, such as Science Direct, PubMed, Wiley Online Library, Springer, and Google Scholar, along with authentic textbooks, were explored as reference literature.

RESULTS

In general, NSAIDs consumption pattern depends upon the different age groups. Around 1.6 billion tablets of NSAIDs are consumed in India for ailments, such as headaches, arthritis, menstrual cramps, osteoarthritis, back pain, rheumatoid arthritis, gout, osteoporosis, tendinitis, cancer pain and chronic pain. Common ADRs of NSAIDs include nausea, vomiting, headache, gastritis, abdominal pain, and diarrhoea. Also, they can cause renal damage and cardiovascular problems if not consumed in a dose-dependent manner. However, Diclofenac and Ibuprofen have both been linked to depression and dementia. There have been reports of aplastic anaemia, agranulocytosis linked to phenylbutazone, Stevens-Johnson, and Lyell's syndrome linked to isoxicam and piroxicam, as well as the vulnerability of new-borns to Reye's syndrome after aspirin use. Lack of awareness, time constraints and unpredictability, poor training in ADRs identification, etc., are some of the reasons for the under-reporting of ADR of NSAIDs in India.

CONCLUSION

In order to rationally prescribe NSAIDs, it is essential to be aware of probable ADR's and establish prescription guidelines. Prescribers' behaviour can be changed toward excellent prescribing practices by conducting routine prescription assessments dealing with NSAIDs and providing feedback. In the near future, it will be critical to strengthen ADR data management and expand the reach of pharmacovigilance programs, ADR monitoring centers, and healthcare professionals' especially pharmacists' training in rural locations.

Pharmacovigilance of herbal medicines: Concerns and future prospects

ETHNOPHARMACOLOGICAL RELEVANCE

The use of herbal medicines for prophylaxis, prevention, and treatment of various ailments is rising throughout the world because they are thought to be safer than allopathic treatments, which they are. However, several investigations have documented the toxicity and adverse drug reactions (ADR) of certain formulations and botanicals if not consumed wisely.

AIM OF THE STUDY

The goal of the current study is to address herbal medication pharmacovigilance (PV) modeling and related considerations for improved patient safety. Also, focus is laid on the comprehensive and critical analysis of the current state of PV for herbal medications at the national and international levels.

MATERIALS AND METHODS

Targeted review also known as focused literature review methodology was utilized for exploring the data from various scientific platforms such as Science Direct, Wiley Online Library, Springer, PubMed, Google Scholar using "pharmacovigilance, herbal medicine, traditional medicine, ADR, under reporting, herb toxicity, herb interactions" as keywords along with standard literature pertaining to herbal medicines that is published by the WHO and other international and national organizations etc. The botanical names mentioned in the present article were authenticated using World Flora Online database.

RESULTS

The historical developments paving the way for PV in regulatory setup were also discussed, along with various criteria's for monitoring herbal medicine, ADR of herbs, phytoconstituents, and traditional medicines, herb-drug interactions, modes of reporting ADR, databases for reporting ADR's, provisions of PV in regulatory framework of different nations, challenges and way forward in PV are discussed in detail advocating a robust drug safety ecosystem for herbal medicines.

CONCLUSION

Despite recent efforts to encourage the reporting of suspected ADRs linked to herbal medicines, such as expanding the programme and adding community pharmacists and other healthcare professionals as recognized reporters, the number of herbal ADR reports received by the regulatory bodies remains comparatively low. Since users often do not seek professional advice or report if they have side effects, under-reporting, is anticipated to be significant for herbal medications. There are inadequate quality control methods, poor regulatory oversight considering herbs used in food and botanicals, and unregulated distribution channels. In addition, botanical identity, traceability of herbs, ecological concerns, over-the-counter (OTC) herbal medicines, patient-physicians barriers requires special focus by the regulatory bodies for improved global safety of herbal medicines.

Implementation of the QbD approach to the development and validation of an analytical method for alpha-beta arteether

Background:

The development of effective, cost-effective, robust, sensitive, and specific analytical techniques for the analysis of drug(s), degradation product(s), and contaminants in dosage forms and biological samples is constantly required as part of the pharmaceutical product life-cycle. The adoption of systematic analytical development methodologies such as quality by design (QbD) is particularly advantageous for enhancing method performance since analytical method development encompasses a number of variables that are significant in explaining variability in method performance. Analytical Quality by Design (AQbD) is a standardised method to process validation that covers all aspects of an analytical procedure. It comprises determining the analytical target profile (ATP), identifying critical method parameters or variables, and selecting critical method attributes (CMAs) or qualities.

Objective:

Spectroscopic and chromatographic methods were developed, conferring the Quality by Design (QbD) tactic as per ICH Q8(R2) guidelines for analytical method development of α-β-arteether.

Method:

Understanding dependent variables, various factors, and their interaction effects through a desired series of experiments on the answers to be examined is referred to as QbD. Various variable factors were detected using the Ishikawa diagram. As a result, many essential factors for chromatography methods were investigated. A desired set of experiments on the answers to be evaluated was used to comprehend dependent variables, various factors, and their interaction effects using Design-Expert software version 13. Statistical research such fractional factorial designs and Plackett-Burman were employed for this. The QbD methodology was used to establish a durable, precise, and accurate HPLC analytical method for arteether.

Result:

Using Design Expert 13's statistical software, the findings of the Plackette Burman research were studied, and the influence of each parameter on the answers was analysed using an overlay plot. Mobile phase (Acetonitrile: water), column C18250nmX4.6mm, column temperature 300 οC, wavelength: 254 nm, injection volume 20l/min, run time 10 mins, detector waters 2489 UV/Visible detector, retention time 4.149 are among the critical parameters estimated for the development of an analytical method for α,β- arteether.

Conclusion:

The analytical method developed by the QbD approach was validated according to ICH Q2(R1) guidelines, and it was found that the developed analytical method is robust and specific.

Formulation Development and assessment of solid dispersion and hydrotropy for BCS Class II drug solubility enhancement

Aim:

This study aimed to evaluate the potential of different hydrophilic polymers to increase Arteether's water solubility.

Background:

Arteether is classified as a class II biopharmaceutical in the Biopharmaceutical Classification System (BCS), with low water solubility (17 g/mL) and dissolution rate, resulting in poor bioavailability.

Objective:

The goal of this research is to improve the water solubility of Arteether (ART) by using a solid dispersion and hydrotropic approach with a variety of carriers, such as PEG-6000 PVP K-30, Poloxamer-188, Poloxamer-407, HPMC E 15LV, HPMC K-100M, sucrose, and mannitol, sodium benzoate, sodium citrate, Urea, nicotinamide, beta-cyclodextrin.

Method:

Melting and evaporation methods were used to make the solid dispersion. Instrumental examinations, including XRD, DSC, FTIR, and SEM, confirmed any physical changes caused by the interaction of ART and carriers.

Results:

The most significant increase in water solubility of Arteether was discovered with CD: PEG600:Pol -407, the highest enhancement in solubility is 67 times. While, 37.34 times, 49 times increase in solubility was observed in 1:4.3:3.7 weight ratio of AE: PEG-6000:Poloxamer-407 40 percent mix of nicotinamide respectively. The in-vitro results show that ART's dissolution rate in the solid dispersion system was dramatically reduced compared to pure drug. This might be because of the drug's enhanced wettability, dispersion ability, and transition from crystalline to amorphous form. Compared to the ART itself, the permeability of Arteether from solid dispersion was increased up to 7 times. However, the permeability of solid cyclodextrin dispersion is extremely low, just 4.42 times. This may be due to the drug encapsulation in the cyclodextrin cavity.

Conclusion:

This research successfully developed and optimized various polymer and solubility enhancement approaches for Arteether, resulting in increased water solubility, which may improve Arteether's oral bioavailability. The findings of this study might be utilized to develop an oral dosage of Arteether with enhanced bioavailability.

Potential of Phytomolecules in Sync with Nanotechnology to Surmount the Limitations of Current Treatment Options in the Management of Osteoarthritis

Osteoarthritis (OA), a chronic degenerative musculoskeletal disorder, progressively increases with old age. It is characterized by progressive loss of hyaline cartilage followed by subchondral bone remodelling and inflammaging. To counteract the inflammation, synovium pours various inflammatory and immune mediators along with metabolic intermediates which further worsen the condition. However, even after recognizing the key molecular and cellular factors involved in the progression of OA, only disease-modifying therapies are available such as oral and topical NSAIDs (Non-steroidal anti-inflammatory drugs), Opioids, SNRIs (Serotonin-norepinephrine reuptake inhibitors), etc addressing symptomatic treatment and functional improvement in lieu of suppressing OA progression. Long term use of these therapies leads to various life-threatening complications. Interestingly, mother nature has numerous medicinal plants containing active phytochemicals that can act on various targets involved in the development and progression of OA. Phytochemicals have been used for millennia in traditional herbalism and are promising alternatives with a lower rate of adverse events and efficiency frequently comparable to synthetic molecules. Nevertheless, their mechanism of action in many cases are elusive and/or uncertain. Even though many in vitro and in vivo studies show promising results, clinical evidence is scarce. Studies suggests that, presence of carbonyl group at 2nd, chloro at 6th along with electron withdrawing group at the 7th position exhibited enhanced COX-2 (Cyclo-oxygenase-2) inhibition activity in OA. On the other hand, the presence of a double bond at C2-C3 position of C ring in flavonoids plays an important role in Nrf2 activation. Moreover, with the advancements in the understanding of OA progression, SARs (Structure activity relationships) of phytochemicals and integration with nanotechnology have given great opportunities to develop phytopharmaceuticals. Therefore, in the present review, we have discussed various promising phytomolecules, SAR as well as their nano-based delivery systems for the treatment of OA to motivate the future investigation of phytochemical based drug therapy.

A Role for Extracellular Vesicles in SARS-CoV-2 Therapeutics and Prevention

Extracellular vesicles (EVs) are the common designation for ectosomes, microparticles and microvesicles serving dominant roles in intercellular communication. Both viable and dying cells release EVs to the extracellular environment for transfer of cell, immune and infectious materials. Defined morphologically as lipid bi-layered structures EVs show molecular, biochemical, distribution, and entry mechanisms similar to viruses within cells and tissues. In recent years their functional capacities have been harnessed to deliver biomolecules and drugs and immunological agents to specific cells and organs of interest or disease. Interest in EVs as putative vaccines or drug delivery vehicles are substantial. The vesicles have properties of receptors nanoassembly on their surface. EVs can interact with specific immunocytes that include antigen presenting cells (dendritic cells and other mononuclear phagocytes) to elicit immune responses or affect tissue and cellular homeostasis or disease. Due to potential advantages like biocompatibility, biodegradation and efficient immune activation, EVs have gained attraction for the development of treatment or a vaccine system against the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection. In this review efforts to use EVs to contain SARS CoV-2 and affect the current viral pandemic are discussed. An emphasis is made on mesenchymal stem cell derived EVs' as a vaccine candidate delivery system.

Diagnostics for SARS-CoV-2 infections

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread to nearly every corner of the globe, causing societal instability. The resultant coronavirus disease 2019 (COVID-19) leads to fever, sore throat, cough, chest and muscle pain, dyspnoea, confusion, anosmia, ageusia and headache. These can progress to life-threatening respiratory insufficiency, also affecting the heart, kidney, liver and nervous systems. The diagnosis of SARS-CoV-2 infection is often confused with that of influenza and seasonal upper respiratory tract viral infections. Due to available treatment strategies and required containments, rapid diagnosis is mandated. This Review brings clarity to the rapidly growing body of available and in-development diagnostic tests, including nanomaterial-based tools. It serves as a resource guide for scientists, physicians, students and the public at large.

Nanocarrier vaccines for SARS-CoV-2

The SARS-CoV-2 global pandemic has seen rapid spread, disease morbidities and death associated with substantive social, economic and societal impacts. Treatments rely on re-purposed antivirals and immune modulatory agents focusing on attenuating the acute respiratory distress syndrome. No curative therapies exist. Vaccines remain the best hope for disease control and the principal global effort to end the pandemic. Herein, we summarize those developments with a focus on the role played by nanocarrier delivery.

Pharmacotherapeutics of SARS-CoV-2 Infections

The COVID-19 pandemic has affected more than 38 million people world-wide by person to person transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therapeutic and preventative strategies for SARS-CoV-2 remains a significant challenge. Within the past several months, effective treatment options have emerged and now include repurposed antivirals, corticosteroids and virus-specific antibodies. The latter has included convalescence plasma and monoclonal antibodies. Complete viral eradication will be achieved through an effective, safe and preventative vaccine. To now provide a comprehensive summary for each of the pharmacotherapeutics and preventative strategies being offered or soon to be developed for SARS-CoV-2.

A Review on Robust Computational Approaches Based Identification and Authentication of Herbal Raw Drugs

Background:

Over the last decade, there has been a sudden rise in the demand for herbal as well as Information and Technology (IT) industry around the world. Identification of plant species has become useful and relevant to all the members of the society including farmers, traders, hikers, etc. Conventional authentication techniques such as morphological characterization, histological methods, and optical microscopy require multiple skills which are tedious, timeconsuming and difficult to learn for non-experts. This creates a hurdle for individuals interested in acquiring knowledge of species. Relying on rapid, economical and computerized approaches to identify and authenticate medicinal plants has become a recent development.

Objective:

The purpose of this review is to summarize artificial intelligence-based technologies for wider dissemination of common plant-based knowledge such as identification and authentication to common people earlier limited to only experts.

Methods:

A robust plant identification design enabling automated plant-organ and feature-based identification utilizing pattern recognition and image processing techniques resulting in image retrieval and recognition has been highlighted in this review for all the concerned stakeholders. Attempts have been made to compare conventional authentication methods with advanced computerized techniques to emphasize the advantages and future applications of an automated identification system in countering adulteration and providing fair trade opportunities to farmers.

Results:

Major findings suggested that microscopical features such as shape and size of calcium oxalate crystals, trichomes, scleriods, stone cells, fibers, etc. are the essential descriptors for identification and authentication of herbal raw drugs using computational approaches.

Conclusion:

This computational design can be successfully employed to address quality issues of medicinal plants. Therefore, computational techniques proved as a milestone in the growth of agriculture and medicinal plant industries.

Medical students as feedback assessors in a faculty development program: Implications for the future

Background: Little is known about simulated students' ability in assessing feedback received in Objective Structured Teaching Encounters (OSTEs). We aimed to assess to which extent students' perceptions matched objective analysis regarding quality of received feedback, to explore what elements of feedback they emphasized and what they learned about feedback.Methods: In this mixed-method study, 43 medical students participated as simulated residents in five OSTEs at Geneva University Hospitals. They assessed quality of feedback from faculty using a 15-item questionnaire and gave written/oral comments. Videotaped feedbacks were assessed using an 18-item feedback scale. During four focus groups, 25 students were asked about what they learned as feedback assessors.Results: 453 students' questionnaires and feedback scale were compared. Correlations were moderate for stimulating self-assessment (0.48), giving a balanced feedback (0.44), checking understanding (0.47) or planning (0.43). Students' feedback emphasized elements such as faculty's empathy or ability to give concrete advice. They reported that being a feedback assessor helped them to realize importance of making the learner active and that giving effective feedback required structure and skills.Conclusion: Medical students may identify quality of feedback. Involving them in OSTEs could be interesting to train them to become valid raters of supervisors' teaching skills.

Methods for registering and calibrating in vivo terahertz images of cutaneous burn wounds

A method to register THz and visible images of cutaneous burn wounds and to calibrate THz image data is presented. Images of partial and full thickness burn wounds in 9 rats were collected over 435 mins. = 7.25 hours following burn induction. A two-step process was developed to reference the unknown structure of THz imaging contrast to the known structure and the features present in visible images of the injury. This process enabled the demarcation of a wound center for each THz image, independent of THz contrast. Threshold based segmentation enabled the automated identification of air (0% reflectivity), brass (100% reflectivity), and abdomen regions within the registered THz images. Pixel populations, defined by the segmentations, informed unsupervised image calibration and contrast warping for display. The registered images revealed that the largest variation in THz tissue reflectivity occurred superior to the contact region at ~0.13%/min. Conversely the contact region showed demonstrated an ~6.5-fold decrease at ~0.02%/min. Exploration of occlusion effects suggests that window contact may affect the measured edematous response.

THz imaging system for in vivo human cornea

Terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early, accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and rigid dielectric window used to flatten the imaging field. This work develops a novel imaging system and image reconstruction methods specifically for nearly spherical targets such as human cornea. A prototype system was constructed using a 650 GHz multiplier source and Schottky diode detector. Resolution and imaging field strength measurement from characterization targets correlate well with those predicted by the quasioptical theory and physical optics analysis. Imaging experiments with corneal phantoms and ex vivo corneas demonstrate the hydration sensitivity of the imaging system and reliable measurement of CTWC. We present successful acquisition of non-contact THz images of in vivo human cornea, and discuss strategies for optimizing the imaging system design for clinical use.

Optical System Design for Noncontact, Normal Incidence, THz Imaging of in vivo Human Cornea

Reflection mode Terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early, accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and dielectric windows used to flatten the imaging field. Herein, we present an optical design for non-contact THz imaging of cornea. A beam scanning methodology performs angular, normal incidence sweeps of a focused beam over the corneal surface while keeping the source, detector, and patient stationary. A quasioptical analysis method is developed to analyze the theoretical resolution and imaging field intensity profile. These results are compared to the electric field distribution computed with a physical optics analysis code. Imaging experiments validate the optical theories behind the design and suggest that quasioptical methods are sufficient for designing of THz corneal imaging systems. Successful imaging operations support the feasibility of non-contact in vivo imaging. We believe that this optical system design will enable the first, clinically relevant, in vivo exploration of CTWC using THz technology.

Terahertz Imaging of Cutaneous Edema: Correlation With Magnetic Resonance Imaging in Burn Wounds

OBJECTIVE

In vivo visualization and quantification of edema, or 'tissue swelling' following injury, remains a clinical challenge. Herein, we investigate the ability of reflective terahertz (THz) imaging to track changes in tissue water content (TWC)-the direct indicator of edema-by comparison to depth-resolved magnetic resonance imaging (MRI) in a burn-induced model of edema.

METHODS

A partial thickness and full thickness burns were induced in an in vivo rat model to elicit unique TWC perturbations corresponding to burn severity. Concomitant THz surface maps and MRI images of both burn models were acquired with a previously reported THz imaging system and T₂-weighted MRI, respectively, over 270 min. Reflectivity was analyzed for the burn contact area in THz images, while proton density (i.e., mobile TWC) was analyzed for the same region at incrementally increasing tissue depths in companion, transverse MRI images. A normalized cross correlation of THz and depth-dependent MRI measurements was performed as a function of time in histologically verified burn wounds.

RESULTS

For both burn types, strong positive correlations were evident between THz reflectivity and MRI data analyzed at greater tissue depths (>258 μm). MRI and THz results also revealed biphasic trends consistent with burn edema pathogenesis.

CONCLUSION

This paper offers the first in vivo correlative assessment of mobile TWC-based contrast and the sensing depth of THz imaging.

SIGNIFICANCE

The ability to implement THz imaging immediately following injury, combined with TWC sensing capabilities that compare to MRI, further support THz sensing as an emerging tool to track fluid in tissue.

Non-invasive terahertz imaging of tissue water content for flap viability assessment

Accurate and early prediction of tissue viability is the most significant determinant of tissue flap survival in reconstructive surgery. Perturbation in tissue water content (TWC) is a generic component of the tissue response to such surgeries, and, therefore, may be an important diagnostic target for assessing the extent of flap viability in vivo. We have previously shown that reflective terahertz (THz) imaging, a non-ionizing technique, can generate spatially resolved maps of TWC in superficial soft tissues, such as cornea and wounds, on the order of minutes. Herein, we report the first in vivo pilot study to investigate the utility of reflective THz TWC imaging for early assessment of skin flap viability. We obtained longitudinal visible and reflective THz imagery comparing 3 bipedicled flaps (i.e. survival model) and 3 fully excised flaps (i.e. failure model) in the dorsal skin of rats over a postoperative period of 7 days. While visual differences between both models manifested 48 hr after surgery, statistically significant (p < 0.05, independent t-test) local differences in TWC contrast were evident in THz flap image sets as early as 24 hr. Excised flaps, histologically confirmed as necrotic, demonstrated a significant, yet localized, reduction in TWC in the flap region compared to non-traumatized skin. In contrast, bipedicled flaps, histologically verified as viable, displayed mostly uniform, unperturbed TWC across the flap tissue. These results indicate the practical potential of THz TWC sensing to accurately predict flap failure 24 hours earlier than clinical examination.

An examination of the elastic properties of tissue-mimicking phantoms using vibro-acoustography and a muscle motor system

Tissue hardness, often quantified in terms of elasticity, is an important differentiating criterion for pathological identity and is extensively used by surgeons for tumor localization. Delineation of malignant regions from benign regions is typically performed by visual inspection and palpation. Although practical, this method is highly subjective and does not provide quantitative metrics. We have previously reported on Vibro-Acoustography (VA) for tumor delineation. VA is unique in that it uses the specific, non-linear properties of tumor tissue in response to an amplitude modulated ultrasound beam to generate spatially resolved, high contrast maps of tissue. Although the lateral and axial resolutions (sub-millimeter and sub-centimeter, respectively) of VA have been extensively characterized, the relationship between static stiffness assessment (palpation) and dynamic stiffness characterization (VA) has not been explicitly established. Here we perform a correlative exploration of the static and dynamic properties of tissue-mimicking phantoms, specifically elasticity, using VA and a muscle motor system. Muscle motor systems, commonly used to probe the mechanical properties of materials, provide absolute, quantitative point measurements of the elastic modulus, analogous to Young's modulus, of a target. For phantoms of varying percent-by-weight concentrations, parallel VA and muscle motor studies conducted on 18 phantoms reveal a negative correlation (p < - 0.85) between mean signal amplitude levels observed with VA and calculated elastic modulus values from force vs. indentation depth curves. Comparison of these elasticity measurements may provide additional information to improve tissue modeling, system characterization, as well as offer valuable insights for in vivo applications, specifically surgical extirpation of tumors.

Pharmaceutical and biomedical applications of quantum dots

Quantum dots (QDs) have captured the fascination and attention of scientists due to their simultaneous targeting and imaging potential in drug delivery, in pharmaceutical and biomedical applications. In the present study, we have exhaustively reviewed various aspects of QDs, highlighting their pharmaceutical and biomedical applications, pharmacology, interactions, and toxicological manifestations. The eventual use of QDs is to dramatically improve clinical diagnostic tests for early detection of cancer. In recent years, QDs were introduced to cell biology as an alternative fluorescent probe.

Preliminary results of non-contact THz imaging of cornea

This paper presents a novel THz optical design that allows the acquisition of THz reflectivity maps of in vivo cornea without the need for a field flattening window and preliminary imaging results of in vivo rabbit cornea. The system's intended use is to sense small changes in corneal tissue water content (CTWC) that can be precursors for a host of diseases and pathologies. Unique beam optics allows the scanning of a curved surface at normal incidence while keeping the source detector and target stationary. Basic system design principles are discussed and image sets of spherical calibration targets and corneal phantom models are presented. The presented design will enable, for the first time, non-contact THz imaging of animal and human cornea.

THz and mm-Wave Sensing of Corneal Tissue Water Content: In Vivo Sensing and Imaging Results

A pulsed terahertz (THz) imaging system and millimeter-wave reflectometer were used to acquire images and point measurements, respectively, of five rabbit cornea in vivo. These imaging results are the first ever produced of in vivo cornea. A modified version of a standard protocol using a gentle stream of air and a Mylar window was employed to slightly dehydrate healthy cornea. The sensor data and companion central corneal thickness (CCT) measurements were acquired every 10-15 min over the course of two hours using ultrasound pachymmetry.. Statistically significant positive correlations were established between CCT measurements and millimeter wave reflectivity. Local shifts in reflectivity contrast were observed in the THz imagery; however, the THz reflectivity did not display a significant correlation with thickness in the region probed by the 100 GHz and CCT measurements. This is explained in part by a thickness sensitivity at least 10× higher in the mm-wave than the THz systems. Stratified media and effective media modeling suggest that the protocol perturbed the thickness and not the corneal tissue water content (CTWC). To further explore possible etalon effects, an additional rabbit was euthanized and millimeter wave measurements were obtained during death induced edema. These observations represent the first time that the uncoupled sensing of CTWC and CCT have been achieved in vivo.

THz and mm-Wave Sensing of Corneal Tissue Water Content: Electromagnetic Modeling and Analysis

Terahertz (THz) spectral properties of human cornea are explored as a function of central corneal thickness (CCT) and corneal water content, and the clinical utility of THz-based corneal water content sensing is discussed. Three candidate corneal tissue water content (CTWC) perturbations, based on corneal physiology, are investigated that affect the axial water distribution and total thickness. The THz frequency reflectivity properties of the three CTWC perturbations were simulated and explored with varying system center frequency and bandwidths (Q-factors). The modeling showed that at effective optical path lengths on the order of a wavelength the cornea presents a lossy etalon bordered by air at the anterior and the aqueous humor at the posterior. The simulated standing wave peak-to-valley ratio is pronounced at lower frequencies and its effect on acquired data can be modulated by adjusting the bandwidth of the sensing system. These observations are supported with experimental spectroscopic data. The results suggest that a priori knowledge of corneal thickness can be utilized for accurate assessments of corneal tissue water content. The physiologic variation of corneal thickness with respect to the wavelengths spanned by the THz band is extremely limited compared to all other structures in the body making CTWC sensing unique amongst all proposed applications of THz medical imaging.

In vivo terahertz imaging of rat skin burns

A reflective, pulsed terahertz (THz) imaging system was used to acquire high-resolution (d(10-90)/λ~1.925) images of deep, partial thickness burns in a live rat. The rat's abdomen was burned with a brass brand heated to ~220°C and pressed against the skin with contact pressure for ~10 sec. The burn injury was imaged beneath a Mylar window every 15 to 30 min for up to 7 h. Initial images display an increase in local water concentration of the burned skin as evidenced by a marked increase in THz reflectivity, and this likely correlates to the post-injury inflammatory response. After ~1 h the area of increased reflectivity consolidated to the region of skin that had direct contact with the brand. Additionally, a low reflecting ring of tissue could be observed surrounding the highly reflective burned tissue. We hypothesize that these regions of increased and decreased reflectivity correlate to the zones of coagulation and stasis that are the classic foundation of burn wound histopathology. While further investigations are necessary to confirm this hypothesis, if true, it likely represents the first in vivo THz images of these pathologic zones and may represent a significant step forward in clinical application of THz technology.

THz Medical Imaging: in vivo Hydration Sensing

The application of THz to medical imaging is experiencing a surge in both interest and federal funding. A brief overview of the field is provided along with promising and emerging applications and ongoing research. THz imaging phenomenology is discussed and tradeoffs are identified. A THz medical imaging system, operating at ~525 GHz center frequency with ~125 GHz of response normalized bandwidth is introduced and details regarding principles of operation are provided. Two promising medical applications of THz imaging are presented: skin burns and cornea. For burns, images of second degree, partial thickness burns were obtained in rat models in vivo over an 8 hour period. These images clearly show the formation and progression of edema in and around the burn wound area. For cornea, experimental data measuring the hydration of ex vivo porcine cornea under drying is presented demonstrating utility in ophthalmologic applications.

Alkaptonuria

A case of alkaptonuria, a rare autosomal recessive metabolic disorder is being reported. The patient presented with passage of dark coloured urine, cutaneous and scleral pigmentation and joint pains. The diagnosis was confirmed by the detection of homogentisic acid in the urine.

Thallium myocardial scintigraphy in congenitally-corrected transposition of the great arteries

A case of congenitally-corrected transposition of the great arteries is presented with the correlation of thallium scintigraphic results with catheterization data. The essential features of the thallium scintigrams were marked counterclockwise rotation of the heart with perfusion abnormalities of the inferior wall and apex. Since patients with congenitally-corrected transposition of the great arteries may present with the symptom of chest pain, the diagnosis of transposition of the great arteries should be considered in patients with marked counterclockwise rotation of the heart and segmental perfusion abnormalities on thallium scintigraphy.