Walfre Franco

University of Massachusetts Lowell | UML · Department of Biomedical Engineering

Objective The objective of this study was to develop a patch that can be placed on the skin during laser hair removal and similar procedures, that serves to reduce the laser-induced plume, provides a ready indicator to the laser surgeon of where pulses have been applied, and cools the skin. Methods A two-layer patch composed of a cooling hydrogel...

Background and Objectives Carbon monoxide (CO) poisoning is responsible for nearly 50,000 emergency department visits and 1200 deaths per year. Compared to oxygen, CO has a 250-fold higher affinity for hemoglobin (Hb), resulting in the displacement of oxygen from Hb and impaired oxygen delivery to tissues. Optimal treatment of CO-poisoned patients...

Ascites refers to the abnormal accumulation of fluid in the peritoneum resulting from an underlying pathology, such as metastatic cancer. Among all cancers, advanced-stage epithelial ovarian cancer is most frequently associated with the production of malignant ascites and is the leading cause of death from gynecologic malignancies. Despite decades...

Background and objectives: Carbon monoxide (CO) inhalation is the leading cause of poison-related deaths in the United States. CO binds to hemoglobin (Hb), displaces oxygen, and reduces oxygen delivery to tissues. The optimal treatment for CO poisoning in patients with normal lung function is the administration of hyperbaric oxygen (HBO). However,...

Tissue engineered organoids are simple biomodels that can emulate the structural and functional complexity of specific organs. Here, we review developments in three-dimensional (3D) artificial cell constructs to model gastrointestinal dynamics towards cancer diagnosis. We describe bottom-up approaches to fabricate close-packed cell aggregates, from...

Background and Objectives Mycological diagnosis of onychomycosis is based on direct microscopy using external fluorophores to visualize fungal tissue in nail samples and agar culture. Ultraviolet fluorescence excitation imaging (u‐FEI) has shown potential in monitoring biological processes by exploiting variations in autofluorescence. This study ai...

A key reason for the persistently grim statistics associated with metastatic ovarian cancer is resistance to conventional agents, including platinum-based chemotherapies. A major source of treatment failure is the high degree of genetic and molecular heterogeneity, which results from significant underlying genomic instability, as well as stromal an...

Build-up of extracellular matrix in liver fibrosis results in changes on endogenous molecules expression that may be studied through the fluorescence characterization of ex vivo liver samples. To the best of our knowledge, no investigations have provided in-depth evidence and discussion on the changes of the endogenous fluorescence in ex vivo tissu...

Many skin diseases are defined by the presence of neutrophils, which are among the first cells to respond to infection and inflammation. Currently, neutrophil identification in the skin is costly and slow. The objectives of the present work are to investigate the feasibility of detecting the presence of neutrophils in live skin microsamples using c...

A novel strategy is needed for treating non-healing wounds that is able to simultaneously eradicate pathogenic bacteria and promote tissue regeneration. This would improve patient outcome and reduce the number of lower limb amputations. In this work, we present a multifunctional therapeutic approach able to control bacterial infection, provide a pr...

The skin is the largest organ in the human body; however, it is only a few millimeters thick. Among the main functions of the skin are to serve as a barrier for protection against physical and biological insults, as a thermal regulator to control internal temperatures, and as a sensor of physical stimulus that could lead to pleasant or harmful expe...

Inhaled carbon monoxide (CO) displaces oxygen from hemoglobin, reducing the capacity of blood to carry oxygen. Current treatments for CO-poisoned patients involve administration of 100% oxygen; however, when CO poisoning is associated with acute lung injury secondary to smoke inhalation, burns, or trauma, breathing 100% oxygen may be ineffective. V...

Measurement of muscle oxygenation in humans can be used to learn critical information about hypoxia during surgery, muscle performance during sports and exercises, severity of septic shock and in other similar situations. In the present work we have developed a minimally invasive optical sensor based on the diffusion model of light transport. It us...

This manuscript describes the production process for a laboratory apparatus, made from off-the-shelf components, that can be used to collect microcolumns of full-thickness skin tissue. The small size of the microcolumns allows donor sites to heal quickly without causing donor site scarring, while harvesting full-thickness tissue enables the incorpo...

Background and Objective Dermatophytes are fungi that cause infections in hair, skin, and nails. Potassium Hydroxide (KOH) microscopy is the most frequently used method for identifying dermatophytes. KOH helps in the visualization of the hyphae as it clears the debris present in the specimen but needs a trained eye for final diagnosis of the infect...

Objective The identification of veins by medical personnel is a critical skill that is necessary to draw blood or administer intravenous fluids and medications. Because a normal consumer camera can act as a multispectral imaging apparatus, operating with three broadband detectors, we hypothesized that a standard smartphone camera might be employed...

Keratoconus is an eye disease in which the cornea progressively deforms due to loss of cornea mechanical rigidity, and thus causes deterioration of visual acuity. Techniques to characterize the mechanical characteristics of the cornea are important to better monitor changes and response to treatments. To investigate the feasibility of using the end...

In many dermatological applications, lowering the temperature of skin and maintaining specific temperatures for extended periods of time are fundamental requirements for treatment; for example, in targeting adipose tissue and managing cutaneous pain. In this work we investigate the feasibility of using phase changing materials (PCMs) as an alternat...

The degeneration of articular cartilage is the main cause of osteoarthritis (OA), a common cause of disability among elderly patients. The aim of this study is to understand the correlation between intrinsic fluorescence of articular cartilage and its biomechanical properties in patients with osteoarthritis. Cylindrical samples of articular cartila...

Background and Objectives: Keratoconus is a disease characterized by progressive steepening and thinning of the cornea, altering visual acuity and sometimes potentiating the need for corneal transplant if the disease progresses.1–3 Corneal crosslinking, a procedure that uses topical riboflavin and UV light to increase the stiffness of the cornea th...

Non-subjective, minimally-invasive, and quantifying techniques may support development and evaluation of a fibrosis regression treatment. The build-up of extracellular matrix in liver fibrosis may result on changes of the endogenous fluorescence of tissue. In this work, we evaluate the fluorescence excitation/emission matrix in the UV range for sev...

Purpose: A clinical treatment option for keratoconus involves the use of UV-initiated photo-crosslinking with riboflavin to increase corneal stiffness. Our study investigates whether endogenous fluorescence changes following treatment for keratoconus can be correlated to alterations in the stiffness of the cornea, thereby guiding treatment of kera...

The aim of our study was to identify fluorescence excitation-emission pairs correlated with atherosclerotic pathology in ex-vivo human aorta. Wide-field images of atherosclerotic human aorta were captured using UV and visible excitation and emission wavelength pairs of several known fluorophores to investigate correspondence with gross pathologic f...

Sprayable formulations of AgNPs were prepared by exchanging citrate capping agents with LL37-SH peptides. The AgNP@LL37 material was then combined with type I collagen to form a stable film once sprayed. The AgNP@LL37 spray prevented Pseudomonas aeruginosa (P. aeruginosa) proliferation and eradicated a P. aeruginosa biofilm, while being non-toxic f...

Background: Carbon monoxide (CO) poisoning is a common cause of poison-related mortality. CO binds to hemoglobin in the blood to form carboxyhemoglobin (COHb), impairing oxygen delivery to peripheral tissues. Current treatment of CO poisoned patients involves oxygen administration to rapidly remove CO and restore oxygen delivery. Light dissociates...

A significant source of morbidity in the elderly population of the United States is osteoarthritis (OA), a disease caused by the breakdown and loss of articular cartilage. The exact causes of OA remain unknown, though biomechanical forces and biochemical alterations are important factors. There exists an unmet need for an imaging tool to identify e...

Background and objective: Molecules native to tissue that fluoresce upon light excitation can serve as reporters of cellular activity and protein structure. In skin, the fluorescence ascribed to tryptophan is a marker of cellular proliferation, whereas the fluorescence ascribed to cross-links of collagen is a structural marker. In this work, we in...

The skin contains several fluorescent molecules or fluorophores that serve as markers of structure, function and composition. UV fluorescence excitation photography is a simple and effective way to image specific intrinsic fluorophores, such as the one ascribed to tryptophan which emits at a wavelength of 345 nm upon excitation at 295 nm, and is a...

Background: The evaluation and treatment of wounds in clinics and hospitals pose a significant challenge; for example, the assessment of wound closure. Current clinical methods for evaluating wound closure are primarily based on observation and conventional color photographs, which among other subjective factors depend on interpretation. The objecti...

Degradation and destruction of articular cartilage is the etiology of osteoarthritis (OA), an entity second only to cardiovascular disease as a cause of disability in the United States. Joint mechanics and cartilage biochemistry are believed to play a role in OA; an optical tool to detect structural and chemical changes in articular cartilage might...

The stiffness or rigidity of the extracellular matrix (ECM) regulates cell response. Established mechanical tests to measure stiffness, such as indentation and tensile tests, are invasive and destructive to the sample. Endogenous or native molecules to cells and ECM components, like tryptophan and cross-links of collagen, display fluorescence upon...

Background and objective: Collagen gels containing cells are commonly used in tissue engineering, wound healing, and cancer research to investigate the interplay between cells and the extracellular matrix (ECM), as changes in the density and stiffness of the microenvironment are known to play a role in many diseases or pathological conditions. In...

Background: A quantitative, objective and simple method for evaluating wound closure in clinic is still lacking. Previously we developed UV Fluorescence Excitation Imaging (u-FEI) and demonstrated its utility in evaluating the healing of skin wounds in vitro. This method exploits the fluorescence of molecules native to tissue, enabling functional a...

Wound size is a key parameter in monitoring healing. Current methods to measure wound size are often subjective, time-consuming and marginally invasive. Recently, we developed a non-invasive, non-contact, fast and simple but robust fluorescence imaging (u-FEI) method to monitor the healing of skin wounds. This method exploits the fluorescence of na...

Background: Fluorescence excitation provides the ability to interrogate innate molecules whose radiation emission correlates with specific functional states of tissue. Objectives: The present study demonstrates the effectiveness of a novel UV fluorescence excitation photography system in its ability to image rapidly proliferating epidermal skin...

Endogenous molecules that exhibit fluorescence hold the potential to serve as reporters of tissue structure, activity and physiology. Fluorescence excitation spectroscopy is one means to measure and express tissue innate fluorescence. This review focuses on the application of endogenous fluorescence ultraviolet excitation spectroscopy to dermatolog...

Carbon monoxide (CO) exposure is a leading cause of poison-related mortality. CO binds to hemoglobin (Hb) forming carboxyhemoglobin (COHb) and produces tissue damage. Treatment of CO poisoning requires rapid removal of CO and restoration of oxygen delivery. Visible light is known to effectively dissociate CO from Hb, with a single photon dissociati...

Collagen is a long fibrous structural protein that imparts mechanical support, strength and elasticity to many tissues. The state of the tissue mechanical environment is related to tissue physiology, disease and function. In the cornea, the collagen network is responsible for its shape and clarity; disruption of this network results in degradation...

Molecules native to tissue that fluoresce upon light excitation can serve as reporters of cellular activity and protein structure. In skin, the fluorescence ascribed to tryptophan is a marker of cellular proliferation, whereas the fluorescence ascribed to crosslinks of collagen is a structural marker. In this work, we introduce and demonstrate a si...

Background and objective: Radiofrequency currents are commonly used in dermatology to treat cutaneous and subcutaneous tissues by heating. The subcutaneous morphology of tissue consists of a fine, collagenous and fibrous septa network enveloping clusters of adipocyte cells. The architecture of this network, namely density and orientation of septa,...

As an alternative method to conventional split-thickness skin grafts (STSGs), we recently proposed fractional skin grafting (FSG), which consists in harvesting hundreds of microscopic skin tissue columns (MSTCs) to place them directly into the skin wound (Tam et al., 2013, “Fractional Skin Harvesting: Autologous Skin Graft Without Donor Site Morbid...

Background: Conventional autologous skin grafts are associated with significant donor-site morbidity. This study was conducted to determine feasibility, safety, and efficacy of a new strategy for skin grafting based on harvesting small columns of full-thickness skin with minimal donor-site morbidity. Methods: The swine model was used for this stud...

Background and objectives: Radiofrequency (RF) energy exposure is a popular non-invasive method for generating heat within cutaneous and subcutaneous tissues. Subcutaneous fat consists of fine collagen fibrous septa meshed with clusters of adipocytes having distinct structural, electrical and thermal properties that affect the distribution and dep...

Normal skin barrier function depends on having a viable epidermis, an epithelial layer formed by keratinocytes. The transparent epidermis, which is less than a 100 mum thick, is nearly impossible to see. Thus, the clinical evaluation of re-epithelialization is difficult, which hinders selecting appropriate therapy for promoting wound healing. An im...

Mass stranding of live whales has been explained by proposing many natural or human-related causes. Recent necropsy reports suggest a link between the mass stranding of beaked whales and the use of naval mid-frequency sonar. Surprisingly, whales have experienced symptoms similar to those caused by inert gas bubbles in human divers. Our goal is to d...

At low frequencies (hundreds of kHz to a few MHz), local energy absorption is proportional to the conductivity of tissue and the intensity of the internal electric field. At 1 MHz, the electric conductivity ratio between skin and fat is approximately 10; hence, skin would heat more provided the intensity of the electric field is similar in both tis...

Mass stranding of live whales has been explained by proposing many natural or human-related causes. Recent necropsy reports suggest a link between the mass stranding of beaked whales and the use of naval mid-frequency sonar. Surprisingly, whales have experienced symptoms similar to those caused by inert gas bubbles in human divers. Our goal is to d...

Although the use of radiofrequency (RF) electric currents to treat very different illnesses by surgical means (e.g. cancer, disturbances in cardiac rhythms, or hyperopia) is very recent, the biophysical phenomena in which these surgical techniques are based has been understood for more than 100 years. The aim of this paper is to didactically presen...

The main objective of the present study is to demonstrate the feasibility of utilizing a novel non-invasive radiofrequency (RF) device to induce lethal thermal damage to subcutaneous adipose tissue only by establishing a controlled electric field that heats up fat preferentially. Adipocyte cells in six-well plates were subjected to hyperthermic con...

The objective of the present study was to demonstrate the feasibility of varying the size of the heating volume of subcutaneous adipose tissue using a novel radiofrequency (RF) technology that controls the delivered energy distribution on the skin surface. Changes in the distribution of the electric potential at the skin surface due to frequency ad...

Objective quantification of epidermal melanin concentration (EMC) should be useful in laser dermatology to determine the individual maximum safe radiant exposure (IMSRE). We propose a single-wavelength remittance measurement at 390 nm as an alternative optical method to determine EMC and IMSRE. Remittance spectra (360 to 740 nm), melanin index (MI)...

Cryogen spray cooling (CSC) protects the epidermis from unintended heating during cutaneous laser surgery. The present work investigated the time-dependent flow characteristics of cryogen sprays and correspondent thermal dynamics at the surface of a human tissue phantom. First, a numerical analysis was carried out to evaluate an epoxy block substra...

Cryogen spray cooling (CSC) is an auxiliary procedure to dermatologic laser surgery which consists of pre-cooling the superficial skin layer (epidermis) during laser irradiation of subsurface targets to avoid non-specific epidermal thermal damage. While previous studies have investigated the interaction of cryogen sprays with microscopically smooth...

The present study explores the discrete space of possible hardware placements for a chilled-water network and seeks the optimum under specified criteria. The secondary loop chosen consists of a water-air cooling coil and five pipes: supply, bypass, coil inlet, coil outlet, and return. Chilled water at a constant temperature is driven by a constant...

Radiant exposure (RE) is a critical treatment parameter to be optimized for laser hair removal (LHR). An objective and quantitative method to assess the individual maximum safe radiant exposure (IMSRE) would help clinicians optimize LHR while at the same time providing the safest possible laser therapy. Pulsed photo-thermal radiometry (PPTR) measur...

Presently, cutaneous vascular lesions are treated using a single cryogen spurt and single laser pulse (SCS-SLP), which do not necessarily produce complete lesion removal in the majority of patients. In this study, the feasibility of applying multiple cryogen spurts intermittently with multiple two-wavelength laser pulses (MCS-MTWLP) was studied usi...

Cryogen spray cooling (CSC) has become an integral part of dermatologic laser surgery because of its ability to remove selectively large amounts of heat from human skin in short periods of time, thereby protecting the epidermis from unintended thermal injury. The objective of the present study is to investigate the extent of lateral epidermal prote...