Precise Serial Microregistration Enables Quantitative Microscopy Imaging Tracking of Human Skin Cells In Vivo.

We developed an automated microregistration method that enables repeated in vivo skin microscopy imaging of the same tissue microlocation and specific cells over a long period of days and weeks with unprecedented precision. Applying this method in conjunction with an in vivo multimodality multiphoton microscope, the behavior of human skin cells such as cell proliferation, melanin upward migration, blood flow dynamics, and epidermal thickness adaptation can be recorded over time, facilitating quantitative cellular dynamics analysis. We demonstrated the usefulness of this method in a skin biology study by successfully monitoring skin cellular responses for a period of two weeks following an acute exposure to ultraviolet light.

Impact of cerebral collateral flow on stroke outcomes after carotid stenting.

OBJECTIVE: Internal carotid artery stenosis is a main contributor to recurrent ischemic stroke. This study aimed to evaluate associations between recurrent stroke and changes in prestenting flow direction in the primary collaterals or both primary and secondary collaterals, and the potential interaction between extra- and intracranial arteries. METHODS: This longitudinal study recruited stroke patients without intracranial stenosis who underwent right-side carotid stenting between 2011 and 2019. The main study outcome was recurrent stroke. Predictive factors were anterior circulation flow direction change (ACFDC), posterior circulation flow direction change, and reversal of ophthalmic artery/leptomeningeal anastomosis (ROALA) detected by transcranial color-coded duplex (TCCD) before carotid stenting. Patient follow-up was 9 years. Risk factors for recurrent stroke were identified by Kaplan-Meier plot and Cox regression analyses. RESULTS: A total of 234 patients (mean age 70.88 ± 10.3 years, 86.32% male) were included, and 115 had recurrent stroke. Kaplan-Meier plot showed that patients with left ACFDC and ROALA had worse outcomes than those with ACFDC only, while patients with left ACFDC had worse outcome than those with right ACFDC (both p < 0.001). Cox regression analysis showed that recurrent stoke was associated with ACFDC at right (hazard ratio [95% CI]: 20.988 [2.549-172.790], p < 0.01), left (151.441 [20.100-1140.993], p < 0.001), and both sides (144.889 [19.089-1099.710], p < 0.001). INTERPRETATION: Anterior circulation flow direction change is significantly associated with recurrent stroke in patients with unilateral carotid stenosis. Patients with ACFDC and ROALA together have worse outcomes compared to those with ACFDC only. Prestenting TCCD images help provide definitive information to predict outcomes after carotid stenting.

Can chronic kidney disease staging early predict outcome of large-artery ischemic stroke with impaired renal function?

Background: Ischemic stroke poses a major threat to human beings, and a prompt intravenous thrombolytic management remains the gold standard protocol for stroke sufferers. Although the role of thrombolytic therapy (r-tPA) for ischemic stroke patients and those with underlying impaired renal function has been advocated as effective treating strategy, there is still a lack of investigation as to finding out baseline important variables that are capable of early outcome prediction. Objectives: In this project, we hypothesize that the change of clinical chronic kidney disease (CKD) staging (delta stage = CKD stage after 3-month follow-up - CKD stage at admission) could serve as a crucial predictor of the prognosis of patients. Design: This is a cohort longitudinal retrospective study. Sources and Methods: A total of 765 cerebral artery ischemic stroke patients with impaired renal function were recruited and followed up for 1 year. Among them, 116 had received the thrombolytic treatment (r-tPA) after being evaluated at the triage in the emergency department and the rest had not (non-r-tPA). Propensity-matching was applied to compare the mortality between the r-tPA and non-r-tPA groups. Multiple logistic regression (LR) and decision tree (DT) algorithm were used to identify important prediction factors for mortality as well as the improvement in neurological function. Results: The 1-year mortality rates for r-tPA and non-r-tPA groups were 32.8% and 44.4%, respectively. The propensity-matched odds ratio of mortality for the r-tPA group compared with the non-r-tPA group is 0.469, with p = 0.003. Logistic regressions suggest that age, Hct, diabetes mellitus type 2, coronary artery disease, and delta stage are important factors for mortality for the non-r-tPA group, whereas age, diabetes mellitus type 2, chronic heart failure, hospital day, and delta stage are important factors for the r-tPA group. On the usage of antihypertensive drugs, ACEI/ARB was not associated with mortality (p = 0.198), whereas the diuretic was, with odds ratio at 1.619 (p = 0.025), indicating higher mortality after administration. Both LR and DT analyses indicate that delta stage is the most important predictor. For the r-tPA group, patients with delta stage ⩽0 had a 24% mortality, while that for delta stage >0 the mortality is 75%. For non-r-tPA patients, the corresponding mortalities were 30.9 and 66.3, respectively. Delta stage is also useful for predicting patients' improvement of neurological function, assessed by NIHSS, mRS, and Barthel Index. The areas under the curve for the three assessments are 0.83, 0.835, and 0.663, respectively. Conclusion: Large-artery ischemic stroke patients who received thrombolytic treatment had significantly lower mortality, even when presenting underlying impaired renal function. The change of CKD staging (delta stage) is capable of acting as a powerful clinical baseline surrogate for both r-tPA and non-r-tPA patients in terms of early outcome prediction. Long-term use of diuretics could be potentially harmful to this group of patients. Moreover, delta stage correlates well with clinical long-term neurological functionality assessment (NIHSS, mRS, and Barthel index), which is helpful in aiding urgent clinical decision-making.

Ophthalmic artery flow direction change predicts recurrence of ischemic stroke after carotid stenting: a longitudinal observational study.

BACKGROUND AND PURPOSE: The implantation of carotid artery stents prevents recurrent ischemic stroke in patients with carotid stenosis. This study aimed to investigate associations between change of ophthalmic artery flow (COAF) post carotid stenting and recurrent ischemic stroke, as well as the link toward the anterior and posterior circulations and patients' prognosis after carotid stenting. METHODS: This retrospective, longitudinal cohort study recruited 87 left side carotid stenosed ischemic stroke patients undergoing left side carotid stenting between year of 2009 and 2013, and patients were followed up to 9 years after carotid procedures. Clinical data were derived from medical records. The primary outcome was stroke recurrence. Predictive factors were stenosis > 50% in one intracranial artery and ROAF. Kaplan-Meier and Cox regression analyses were used to identify risk factors associated with stroke recurrence. RESULTS: Among 87 included patients undergone left side carotid stent treatment, 44 had stroke recurrence within 3 years after carotid stenting. The recurrence group had significantly greater proportions of COAF after stenting (p = 0.001), and middle cerebral artery (MCA) and basilar artery or vertebral artery (BA/VA) stenosis > 50% (all p < 0.001) than the no-recurrence group. Survival was significantly shorter in patients with COAF than in those without (p < 0.01). Regression analysis showed that COAF was associated with stroke recurrence (HR: 3.638, 95% CI 1.54-8.62, p = 0.003). The recurrence rate was highest in patients with bilateral MCA stenosis > 50% (100%), followed by left MCA stenosis > 50% plus BA/VA stenosis > 50% (83.33%) or COAF (82.14%). Patients with bilateral MCA stenosis < 50% had no recurrence within 3-year follow-up. CONCLUSIONS: Prognosis after carotid stenting is poorer for patients with MCA stenosis > 50%, BA/VA stenosis > 50% and/or COAF. Carotid duplex and magnetic resonance angiography provide definitive information for prognosis prediction.

Challenges of Large Vessel Vasculitis Stroke Patient with Complicated Endovascular Thrombectomy: A Case Report.

PURPOSE: The causes of acute stroke in patients with SLE are multifactorial. Antiphospholipid-associated hypercoagulability and inflammation-induced platelet activation are major causes of ischemic stroke in SLE patients. As such patients underwent intravenous thrombolysis and endovascular thrombectomy, they may have higher risk of complications and less favorable outcome. CASE REPORT: A 30-year-old woman with underline SLE and Takayasu arteritis who presented with right CCA and MCA occlusion status post rtPA and endovascular thrombectomy. Twelve hours after the procedure, head CT was ordered due to anisocoria with loss of pupillary light reflex. The head CT showed partial obliteration of suprasellar and quadrigeminal cistern due to extensive brain edema, leading to her decompressive craniectomy. Two days later, patient's both pupil became dilated with head CT showing occlusion of the left MCA. Her condition drastically went downhill when complications such as central DI and myocardial stunning occurred. CONCLUSION: Although autoimmune vasculitis is not listed as an absolute contraindication to endovascular thrombectomy, given the antecedent reports, it is prudent to disclose possible complications to both the patient and family while making the decision.

The age factor influencing long-term physical functionality in stroke patients undergoing intra-arterial thrombectomy treatment.

The treatment of acute ischemic stroke is heavily time-dependent, and even though, with the most efficient treatment, the long-term functional outcome is still highly variable. In this current study, the authors selected acute ischemic stroke patients who were qualified for intravenous thrombolysis with recombinant tissue plasminogen activator and followed by intra-arterial thrombectomy. With primary outcome defined by the functional level in a 1-year follow-up, we hypothesize that patients with older age are at a disadvantage in post-stroke recovery. However, an age-threshold should be determined to help clinicians in selection of patients to undergo such therapy. This is a retrospective chart review study that include 92 stroke patients in Changhua Christian hospital with a total of 68 evaluation indexes recorded. The current study utilized the forward stepwise regression model whose Adj-R2 and P value in search of important variables for outcome prediction. The chngpt package in R indicated the threshold point of the age factor directing the better future functionality of the stroke patients. Datasets revealed the threshold of the age set at 79 the most appropriate. Admission Barthel Index, Age, ipsilateral internal carotid artery resistance index (ICA RI), ipsilateral vertebral artery (VA) PI, contralateral middle cerebral artery (MCA) stenosis, contralateral external carotid artery (ECA) RI, and in-hospital pneumonia are the significant predicting variables. The higher the age, in-hospital pneumonia, contralateral MCA stenosis, ipsilateral ICA RI and ipsilateral VA PI, the less likely patient to recover from functional deficits as the result of acute ischemic stroke; the higher the value of contralateral ECA RI and admission Barthel Index, the better chance to full functional recovery at 1-year follow up. Parameters of pre-intervention datasets could provide important information to aid first-line clinicians in decision making. Especially, in patients whose age is above 79 receives diminish return in the benefit to undergo such intervention and should be considered seriously by both the patients and the physicians.

The Efficacy and Adverse Events in Patients with Head and Neck Cancer Following Radiotherapy Combined with S-1 Therapy: A Meta-Analysis.

This meta-analysis was conducted to assess the efficacy and adverse events associated with S-1 chemotherapy combined with radiotherapy for patients with head and neck cancer. The PubMed, Embase, and Cochrane Library databases were searched up to 10 February 2021. Eligible studies included clinical trials using S-1 chemotherapy combined with radiotherapy for head and neck cancer patients that measured tumor response, local control rate, overall survival, and grade 3/4 adverse events. A meta-analysis was performed using a random effects model. Twelve trials involving 378 patients met the selection criteria. The objective response and clinical benefit rate (complete/partial response and stable disease) of S-1 chemotherapy with radiotherapy were 86.3% (95% confidence interval (CI), 60.3-96.3) and 88.3% (95% CI, 70.1-96.1), respectively. The median 3-year local control rate, 3-year overall survival rate, and grade 3/4 adverse event rate were 84.0% (95% CI, 71.4-91.7), 69.6% (95% CI, 54.9-81.1), and 42.0% (95% CI, 36.2-48.0), respectively. S-1 combined with radiotherapy for patients with head and neck squamous cell carcinoma results in a good tumor response, favorable survival rate, and low toxicity. A prospective randomized, double-blind trial is required to assess the efficacy and safety of S-1 combined with radiotherapy to treat HNSCC.

Exploring the Effectiveness of PAC Rehabilitation for Elders with Hip Surgery: A Retrospective Study.

BACKGROUND: Hip fractures are high risk and high-impact events in the elderly population; despite orthopedic hip surgery, the disability and mortality rate remains significant. The National Health Insurance Agency in Taiwan established a fragility fracture PAC rehabilitation program to provide functional recovery for these patients after the surgery. However, the current literature on PAC rehabilitation is outdated, and there is an urgent need for the re-evaluation of the program. METHODS: This is a retrospective cohort study that enrolled 159 patients in the PAC rehabilitation program, followed by hip repair surgery. Outcome measures were the differences in participants' pre- and post-PAC scores in 1) Barthel index, 2) Numerical Rating Scale (NRS), and 3) Harris Hip Scores (HHS) as surrogate indicators of the functional status, followed by the analysis of subgroups, including sex, age, site of the fracture, type of procedure, and the number of comorbidities. RESULTS: After completing PAC rehabilitation, 86.2% of the patients successfully returned to the community with either home or out-patient rehabilitation. The re-admission rate was 3.1% and 3.8% in 14-days and in 30-days follow up, respectively. The difference in pre- and post-Barthel index, NRS, and HHS showed significant improvement (p<0.001), without significant variations between the subgroups. Additionally, the Barthel index showed a positive correlation to HHS and a negative correlation to NRS. CONCLUSION: This study revealed that the current form of post-surgery fragility fracture PAC program effectively improves functional status, reduces the re-admission rate, and facilitates the patient transition back to the community. The results should improve patients' and physicians' confidence in such a program.

Pembrolizumab-induced myasthenia gravis-like disorder, ocular myositis, and hepatitis: a case report.

INTRODUCTION: Pembrolizumab and other immune checkpoint inhibitors are the emerging treatment for selected, high-grade malignancies. However, a small number of patients are unable to tolerate its adverse effects, leading to discontinuation of this potentially life-changing therapy. In this study, we present a case of high-grade urothelial carcinoma patient, who experienced neurocomplications during the first pembrolizumab administration. However, we were able to limit the adverse effect by concomitant use of low-dose oral steroids. CASE PRESENTATION: A 75-year-old Taiwanese female with high-grade urothelial carcinoma of the left ureter came to the neurology clinic with complaints of acute onset of bilateral ptosis 16 days after her first infusion of pembrolizumab. It was found that she developed complete bilateral ptosis and limited extraocular muscle movements. Myasthenia gravis-related antibodies and repetitive stimulation test were negative. We diagnosed her with pembrolizumab-induced myasthenia gravis-like disorder and myositis based on clinical symptoms and elevation of muscle enzymes. We commenced methylprednisolone pulse therapy followed by oral steroid therapy with gradual resolution of the symptoms. Three months later, the patient received a second cycle of pembrolizumab with low-dose oral steroids without any complications. CONCLUSION: Pembrolizumab exerts its antitumor activity by interfering with the binding of programmed death 1 and its ligand, programmed death ligand 1. As a result, enhanced cytotoxic T cells can recognize tumor cells and induce cellular death. However, neurological complications may be severe and require prompt recognition and treatment. Our case demonstrated that concomitant use of low-dose steroids and pembrolizumab might prevent such complications.

A challenging case of neuropsychiatric systematic lupus erythematosus with recurrent antiphospholipid- related stroke: A case report and literature review.

Neuropsychiatic systematic lupus erythematosus (NPSLE) is a form of SLE involves the inflammation and/or thrombotic event in the nervous system. Patients with NPSLE are likely to have a positive antiphospholipid antibody (aPL), therefore are at higher risk of recurrent ischemic stroke. The management of NPSLE with aPLrelated stroke is rather different from the traditional ischemic stroke. One must treat it with anticoagulation and immunosuppressive therapy. The present case is a 47-yearold Taiwanese female with NPSLE and positive aPL, presented with a recurrent MCA ischemic stroke. Initial laboratory results showed significantly elevated levels of anti-ANA, anti-dsDNA, anti-cardiolipin, and decreased complement levels. Due to multiple contraindications for tPA, she was treated with antiplatelet, anticoagulation, steroid pulse therapy, and plasmapheresis during the hospitalization. Despite treatments, her stroke progressed to multi-focal lesions, involving the ACA, MCA, and basal ganglion. On follow up of her brain CT scan showed tissue edema and suspicious for subfalcine herniation. Responding to this clinical deterioration, we stopped warfarin and started mannitol. Eventually, her condition improved and was transferred to the rehabilitation program. Currently, there is no unified guideline regarding the secondary prevention of ischemic stroke in NPSLE with aPL patients. Additionally, previously reported use of steroid pulse therapy and plasmapheresis can potentially harm the patient. Clinicians must be cautious when treating such patient.

Carotid duplex parameters to predict long term outcomes of ischemic stroke patients receiving intra-arterial thrombectomy treatment.

Early treatment of acute ischemic stroke with intravenous thrombolysis therapy (ITT) followed by intra-arterial thrombectomy (IAT) is a promising new treatment option for improving functional outcomes. Identifying patients who will benefit from this treatment combination is important.A total of 92 acute ischemic stroke patients who received ITT and IAT with a minimum of 1-year follow-up were included in the study. All parameters of clinical and imaging examinations at baseline were examined which parameters were significantly correlated with the 1-year functional outcomes (modified Rankin scale [mRS], National Institute of Health Stroke Scale [NIHSS], and Barthel Index) after stroke. Receiver-operating characteristic (ROC) curves analysis was performed to estimate the diagnostic performance of each significantly related parameter. Youden index was used to determine the optimal threshold value. Multivariate logistic regression model analyses were applied to verify the results of predicting the favorable functional outcomes.Immediate postoperation outcome with modified thrombolysis in cerebral infarction grading showed that total of 62 patients qualified for satisfactory result (2b or 3). In predicting NIHSS improvement, ROC curve analysis showed that a cutoff point of vertebral artery pulsatility index (VA PI)-ipsilateral ≤2.3 yields the best diagnostic performance (area under the ROC curve [AUC] = 0.728); in predicting mRS improvement, VA PI-ipsilateral ≤1.92 and internal carotid artery resistance index (ICA RI)-ipsilateral ≤0.71 yield good diagnostic performance (AUC = 0.697 and 0.672, respectively); and ICA RI-contralateral ≤0.70 or plaque index-ipsilateral ≤2 had better diagnostic accuracy (AUC = 0.764 and 0.689, respectively) than other indices to predict Barthel index improvement. The multivariate analysis also showed that these 5 indices were those more powerful and highly significant favorable functional outcomes predictors.Parameters of pulsatility and resistance index from carotid duplex could be easily accessed and noninvasive. The outcome of ischemic stroke patients receiving ITT followed by IAT can be forecasted by these 2 crucial predictors that hint the patients' functional outcomes as well as guiding first line in-charge clinician in terms of decision making.

Aminoglycoside-associated nonsyndromic deafness and speech disorder in mitochondrial A1555G mutation in a family: A case report.

RATIONALE: Mitochondrial DNA mutations have been associated with many maternal inherited diseases. A1555G mutation in mtDNA effects the gene code for rRNA, resulting in the structural change of human ribosome rending it susceptible to binding of the common antibiotic, aminoglycosides. Such mutation has linked with non-syndromic hearing loss and is one of the most common mtDNA mutations in Asian populations. PATIENT CONCERNS: A 50-year-old Taiwanese female visited our neurology department with concern for multiple members with hearing loss in her family, including herself. DIAGNOSES: Physical examination findings were not significant besides hearing loss and brain MRI did not reveal any lesions. BAEP confirmed bilateral peripheral sensory deficit. Given the multiple cases of hearing loss in the family, a genetic cause was suspected. Using PCR and sequences chromatogram technique we have identified A1555G mutation on her mtDNA affecting region codes for 12S rRNA. Additionally, we observed severe speech disorder in two young family members with the onset of hearing loss began in their early childhood. INTERVENTIONS: The patient declined any form of intervention at the time for personal reasons. OUTCOMES: The patient was satisfied with the diagnosis, her and her families are continuously followed by our neurology department. LESSONS: We report on a family with mtDNA mutation hearing loss that is related to exposure to aminoglycosides. Children with such mutation are at high risk for impaired linguistic function. Early identification and intervention with cochlear implant should be considered.

Vertebral artery dissection stroke in evolution presented with postural headache as initial manifestation.

In young adult, the most common etiology of acute ischemic brain infarction are arterial dissections and cardiogenic embolic stroke. Vertebral artery dissection without preceding trauma history is quite rare in young ischemic stroke patients. Postural headache is even more atypical presentation for vertebral artery dissection. It is often misdiagnosed as spontaneous intracranial hypotension. We described a 37-year-old male suffering from acute onset postural headache with stroke in evolution during hospitalization. The initial brain magnetic resonance imaging (MRI) mislead to diagnosis of ischemic lesion. Nevertheless, with the aid of single photon emission computed tomography, we are confident the patient was afflicted with ischemic/hemorrhagic lesion, instead of neoplasm or demyelinating diseases. Lateral medullary syndrome was confirmed on the repeated brain MRI. His general condition improved with steady gait and clear articulation without easychoking after adequate hydration and rehabilitation training with aspirin as secondary prevention. Cranial artery dissections is a crucial differential diagnosis while thunderclap headache happens even related to postural change without obvious neurological deficit in the beginning presentations.

Sun protection by umbrellas and walls.

Solar protection is an important public health issue because solar UV exposure can cause acute and chronic damage to the skin. Seeking shade is a convenient and commonly practiced sun avoidance measure. Shade works by physically shielding the skin from direct UV rays; however UV rays can also reach the skin from other angles. It is not clear how protective the widely-used shade structures like umbrellas and walls are under actual use conditions. In this study, a sky view model was applied to systematically assess the influence of different factors to umbrellas and walls, including the transmission of the shade materials, the reflectivity of the ground or the wall, diffused UV to total UV irradiance ratios, shade geometry, a person's positions and orientations in the shade. We measured the sunburn protection factor (SPF) with a calibrated UV meter at different positions in the shades of an umbrella at different times of the day and compared the measurement results with the modeling. We found that shade structures like umbrellas and walls are more effective when the ratios of diffused UV to total UV irradiance are smaller (mid-day). The effectiveness increases with more coverage, less surface reflectance, and more centralized positions in the shade. The SPF value for a typical umbrella is probably between 3 and 7 in real-life. The low sun protection level offered by a typical shade highlights the importance of educating the public about how to properly protect the skin from the sun and the importance of applying a combination of sun protection measures during extended sun exposures.

Sun Protection by Beach Umbrella vs Sunscreen With a High Sun Protection Factor: A Randomized Clinical Trial.

Importance: Sun-protective behavior affects skin cancer prevention. Shade works by physically shielding skin from direct harmful UV rays; however, skin may still remain exposed to reflected and indirect UV rays. There is no current standard metric to evaluate shade for its effectiveness in sun protection, and there is insufficient clinical evidence that a beach umbrella alone can provide adequate sun protection. Objective: To directly measure sunburn protection offered by a standard beach umbrella compared with that provided by sunscreen with a high sun protection factor under actual use conditions. Design, Setting, and Participants: A single-center, evaluator-blinded, randomized clinical study was conducted from August 13 to 15, 2014, in Lake Lewisville, Texas (elevation, 159 m above sea level), among 81 participants with Fitzpatrick skin types I (n = 1), II (n = 42), and III (n = 38). Participants were randomly assigned to 2 groups: 1 using only a beach umbrella, and the other using only sunscreen with a sun protection factor of 100. All participants remained at a sunny beach for 3½ hours at midday. Clinical sunburn evaluation of each individual for all exposed body sites was conducted 22 to 24 hours after sun exposure. Interventions: The shade provided by a beach umbrella or protection provided by sunscreen with a sun protection factor of 100. Main Outcomes and Measures: Sunburn on all exposed body sites 22 to 24 hours after sun exposure. Results: Among the 81 participants (25 male and 56 female; mean [SD] age, 41 [16] years) for all body sites evaluated (face, back of neck, upper chest, arms, and legs), the umbrella group showed a statistically significant increase in clinical sunburn scores compared with baseline and had higher postexposure global scores than the sunscreen group (0.75 vs 0.05; P < .001). There was a total of 142 sunburn incidences in the umbrella group vs 17 in the sunscreen group. Thirty-two of the 41 participants (78%) in the umbrella group showed erythema in 1 or more sites vs 10 of the 40 participants (25%) in the sunscreen group (P < .001). Neither umbrella nor sunscreen alone completely prevented sunburn. Conclusions and Relevance: A beach umbrella alone may not provide sufficient protection for extended UV exposure. It is important to educate the public that combining multiple sun protection measures may be needed to achieve optimal protection. Trial Registration: isrctn.org Identifier: ISRCTN19177299.

Metal oxide sunscreens protect skin by absorption, not by reflection or scattering.

BACKGROUND/PURPOSE: The inorganic metal oxide sunscreens titanium dioxide and zinc oxide have been considered to protect against sunburning ultraviolet radiation by physically reflecting/scattering the incident photons and thus protecting the skin. Earlier publications suggested, however, that the primary action of UV protection by these sunscreen agents is through absorption and not by reflection. The purpose of this work was to quantitate the contributions of each of these modes of action to the protection provided by inorganic UV sunscreen filters. METHODS: An optical integrating sphere was used to measure the transmission and the reflectance of titanium dioxide and zinc oxide. RESULTS: The average range of reflection for zinc oxide and titanium dioxide throughout the UV range was only 4-5% (less than SPF 2), providing minimal UV protection via this mechanism. The remainder of the UV protection is provided by semiconductor band gap mediated absorbance of the UV photons. At wavelengths above the semiconductor band gap absorption energy levels (in the long UVA and visible wavelengths), they are predominantly reflectors of light (up to 60% reflection) and non-absorbing. CONCLUSION: Titanium dioxide and zinc oxide provide UV protection primarily via absorption of UV radiation and not through significant reflection or scattering.

A broad spectrum high-SPF photostable sunscreen with a high UVA-PF can protect against cellular damage at high UV exposure doses.

BACKGROUND: Advances in sunscreen technologies have yielded broad spectrum sunscreens at high-sun protection factor (SPF) and ultraviolet A protection factor (UVA-PF) levels that are photostable and powerful in protecting skin from erythema. Questions arise whether these sunscreens protect proportionally against cellular skin damage caused by high ultraviolet exposures. OBJECTIVE: The objective of this study is to evaluate if high-SPF sunscreen can protect skin at a cellular level under UV exposure doses [>50 minimal erythema dose (MED)] similarly to the SPF value. METHODS: Sunburn cells, Langerhans cells, thymine dimers, protein 53 (p53), and matrix metalloproteinase (MMP)-1 and MMP-9 endpoints were evaluated in biopsies from 12 subjects following four treatments: unprotected exposed to 0, 1 and 3 MED and sunscreen (SPF 55) protected exposed to 55 MED of UV radiation. RESULTS: All the markers showed significantly more damage for the 3 MED-untreated sites when compared with non-irradiated control, and majority of the markers showed marked damage following unprotected 1 MED exposure. After 55 MEDs, sunscreen-protected sites showed significantly less p53 and MMP-9 (keratinocyte) staining than the 1 MED-exposed unprotected sites, while all the other biomarkers in sunscreen protected sites showed no statistical differences from 1 MED-exposed unprotected sites. CONCLUSIONS: A high-SPF photostable sunscreen with high UVA-PF can provide proportionately high protection against multiple cellular damage markers.

The application of ultra-weak photon emission in dermatology.

Ultra-weak photo emission (UPE) is a phenomenon closely associated with life and provides us a rare window to look into oxidative reactions in life directly without the aid of other agents. Dozens of independent studies have investigated UPE in skin in the last 2 decades. Skin serves as a convenient target for the application of UPE. As the outmost layer of our body, skin is also subjected to the influences from environmental factors such as ultraviolet light. Therefore UPE measurement can help us better understand the interaction between skin and the outside world. A variety of dermatological interventions may benefit from UPE studies. In particular, those treatments aiming to manage the oxidative status of the skin can be monitored directly by UPE measurements. In recent years, UPE has already been used as a valuable in vivo tool to assist the selection of better skin care ingredients and products. The knowledge gained by UPE studies of skin may also help generate new insights and new targets for future treatments. This review emphasizes in vivo and clinical measurement of UPE in skin. The applications of UPE in skin research related to antioxidants and sunscreens are discussed.