Quantification of serum markers of hepatitis B (HBV) and Delta virus (HDV) infections in patients with chronic HDV infection.

The interplay between hepatitis B (HBV) and delta (HDV) viruses is complex and not always characterized during chronic HDV infection. We assessed the clinical usefulness of new quantitative assays for HBV and HDV serum markers in a retrospective cross-sectional study. Sera obtained from 122 HDV genotype 1 and HBV genotype D coinfected, anti-HIV-negative patients (71 males; median age 49.8 [21.7-66.9] years), recruited consecutively in two geographical areas (Italy 69 patients, Romania 53 patients) with different HBV and HDV epidemiology, were tested for HBsAg, HBV-DNA, HBcrAg, total anti-HBc, HDV-RNA, IgM and total anti-HDV using quantitative assays. Cirrhosis, which showed comparable prevalence in the two cohorts, was diagnosed in 97 of 122 (79.5%) patients. At multivariate analysis, cirrhosis was associated with lower total anti-HBc/IgM anti-HDV ratio (OR 0.990, 95% CI 0.981-0.999, P = .038), whereas disease activity was associated with higher total anti-HDV (OR 10.105, 95% CI 1.671-61.107, P = .012) and HDV-RNA levels (OR 2.366, 95% CI 1.456-3.844, P = .001). HDV-RNA serum levels showed a positive correlation with HBV-DNA (ρ = 0.276, P = .005), HBsAg (ρ = 0.404, P < .001) and HBcrAg (ρ = 0.332, P < .001). The combined quantitative profiling of HBV and HDV serum markers identifies specific patterns associated with activity and stage of chronic hepatitis D (CHD). HDV pathogenicity depends on the underlying active HBV infection in spite of the inhibition of its replication. HDV-RNA, IgM anti-HDV, total anti-HDV, total anti-HBc, HBsAg and HBcrAg serum levels qualify for prospective studies to predict progressive CHD and identify candidates to antiviral therapy.

Facial pain: sinus or not?

Facial pain remains a diagnostic and therapeutic challenge for both clinicians and patients. In clinical practice, patients suffering from facial pain generally undergo multiple repeated consultations with different specialists and receive various treatments, including surgery. Many patients, as well as their primary care physicians, mistakenly attribute their pain as being due to rhinosinusitis when this is not the case. It is important to exclude non-sinus-related causes of facial pain before considering sinus surgery to avoid inappropriate treatment. Unfortunately, a significant proportion of patients have persistent facial pain after endoscopic sinus surgery (ESS) due to erroneous considerations on aetiology of facial pain by physicians. It should be taken into account that neurological and sinus diseases may share overlapping symptoms, but they frequently co-exist as comorbidities. The aim of this review was to clarify the diagnostic criteria of facial pain in order to improve discrimination between sinogenic and non-sinogenic facial pain and provide some clinical and diagnostic criteria that may help clinicians in addressing differential diagnosis.

Balancing the effect of corona on therapeutic efficacy and macrophage uptake of lipid nanocapsules.

Several studies have shown the potential of biocompatible lipid nanocapsules as hydrophobic drug delivery systems. Understanding the factors that determine the interactions of these oil-in-water nanoemulsions with cells is a necessary step to guide the design of the most effective formulations. The aim of this study was to probe the ability of two surfactants with a markedly different nature, a non-ionic poloxamer, and a charged phospholipid, to prepare formulations with shells of different composition and different surface properties. Thus we determined their effects on the interaction with biological environments. In particular, we investigated how the shell formulation affected the adsorption of biomolecules from the surrounding biological fluids on the nanocapsule surface (corona formation). A complete physicochemical characterization including an isothermal titration calorimetry (ITC) study revealed that the use of poloxamer led to nanocapsules with a marked reduction in the number of protein-binding sites. Surface hydrophilicity and changes in corona formation strongly correlated to changes in uptake by cancer cells and by macrophages. Our results indicate that the nature and concentration of surfactants in the nanocapsules can be easily manipulated to effectively modulate their surface architecture with the aim of controlling the environmental interactions, thus optimizing functionality for in vivo applications. In particular, addition of surfactants that reduce protein binding can modulate nanoparticle clearance by the immune system, but also screens the desired interactions with cells, leading to lower uptake, thus lower therapeutic efficacy. The two effects need to be balanced in order to obtain successful formulations.

Predictive value of dynamic renal resistive index (DRIN) for renal outcome in type 2 diabetes and essential hypertension: a prospective study.

BACKGROUND: Hypertension (EH) and type 2 diabetes (T2DM) are major causes of chronic kidney disease (CKD) and identification of predictors of CKD onset is advisable. We aimed to assess whether dynamic renal resistive index (DRIN), as well as other markers of systemic vascular damage, are able to predict albuminuria onset and estimated glomerular filtration rate (eGFR) decline in patients with T2DM or EH. METHODS: In this prospective observational cohort study, 27 T2DM and 43 EH patients, free of CKD at baseline, were followed-up for 4.1 ± 0.6 years. Resistive Index (RI), endothelium-dependent (FMD) and independent vasodilation in the brachial artery (after glyceryl trinitrate - GTN - 25 µg s.l.), carotid-femoral Pulse Wave Velocity (PWV), Augmentation Index (AIx), DRIN (%RI change after GTN 25 µg s.l.) were evaluated. RESULTS: Patients developing microalbuminuria were older, more frequently T2DM, with higher UACR at baseline, and showed higher DRIN (-2.8 ± 6.7 vs -10.6 ± 6.4 %, p = 0.01) and PWV (9.9 ± 1.3 vs 7.9 ± 1.5 m/s, p = 0.004) at baseline. The best predictors of microalbuminuria onset were DRIN > -5.16 % in T2DM (sensitivity 0.83, specificity 0.80) and PWV > 8.6 m/s in EH (sensitivity 0.96, specificity 1.00). Individuals whose eGFR declined (n = 27) had higher eGFR at baseline, but similar vascular characteristics; however in EH showing eGFR decline, baseline DRIN and PWV were higher. PWV showed a steeper progression during follow-up in patients developing albuminuria (Visit-outcome interaction: p = 0.01), while DRIN was early compromised but no further impaired (Visit-outcome interaction: p = 0.04). CONCLUSIONS: PWV and DRIN are able to predict microalbuminuria onset in newly diagnosed EH and T2DM. DRIN is early compromised in T2DM patients developing microalbuminuria.

Water polo throwing velocity and kinematics: differences between competitive levels in male players.

AIM: In water polo, throwing is one of the most important and frequently used technical skills for the player. There is no scientific literature that provides information about differences in throwing between elite and sub-elite water polo players. The aim of our study was to study differences in throwing velocities and kinematic variables in elite and sub-elite level male water polo players. METHODS: We considered the variables under standardized conditions during a typical motion, the five-meter shot (penalty). Thirty-four athletes from the Men's First Division Water Polo Championship and forty-two players participating in the National Fourth Division League, took part in the study. Video analysis measures were taken with high-speed digital cameras and the videos were analyzed offline with Dartfish 5.0 Pro. RESULTS: No correlation was found between body mass, height and throwing velocity. Elite players had higher values ​for ball speed (22.8±2.4 m/s for elite team and 18.4±1.7 m/s for sub-elite team; P=0.002) and greater elbow angle (157.5±10.3 degree for elite team versus 146.7±8.9 degree for sub-elite team; P=0.002). In elite team the throwing time was lower (165.6±22.2 and 188.6±23.9 ms, respectively; P=0.05) and the shoulder angle was smaller (115.1±10.3 and 123.8±12.4 degree, respectively; P=0.03) than in sub-elite team. Head height was significantly greater in elite players (elite players 71.1±8.7 cm, sub-elite players 65.6±6.2 cm; P=0.03). CONCLUSION: Differences in kinematic characteristics between elite and sub-elite players were showed. Differences in elbow and shoulder action must be considered both in training and injury prevention.

Accumulation and embryotoxicity of polystyrene nanoparticles at early stage of development of sea urchin embryos Paracentrotus lividus.

Nanoplastic debris, resulted from runoff and weathering breakdown of macro- and microplastics, represents an emerging concern for marine ecosystems. The aim of the present study was to investigate disposition and toxicity of polystyrene nanoparticles (NPs) in early development of sea urchin embryos (Paracentrotus lividus). NPs with two different surface charges where chosen, carboxylated (PS-COOH) and amine (PS-NH2) polystyrene, the latter being a less common variant, known to induce cell death in several in vitro cell systems. NPs stability in natural seawater (NSW) was measured while disposition and embryotoxicity were monitored within 48 h of postfertilization (hpf). Modulation of genes involved in cellular stress response (cas8, 14-3-3ε, p-38 MAPK, Abcb1, Abcc5) was investigated. PS-COOH forms microaggregates (PDI > 0.4) in NSW, whereas PS-NH2 results are better dispersed (89 ± 2 nm) initially, though they also aggregated partially with time. Their respectively anionic and cationic nature was confirmed by ζ-potential measurements. No embryotoxicity was observed for PS-COOH up to 50 µg mL(-1) whereas PS-NH2 caused severe developmental defects (EC50 3.85 µg mL(-1) 24 hpf and EC50 2.61 µg mL(-1) 48 hpf). PS-COOH accumulated inside embryo's digestive tract while PS-NH2 were more dispersed. Abcb1 gene resulted up-regulated at 48 hpf by PS-COOH whereas PS-NH2 induced cas8 gene at 24 hpf, suggesting an apoptotic pathway. In line with the results obtained with the same PS NPs in several human cell lines, also in sea urchin embryos, differences in surface charges and aggregation in seawater strongly affect their embryotoxicity.

Detraining in young soccer players.

BACKGROUND: Two types of detraining can be described: short-term detraining with a period of less than 4 weeks, and long-term detraining (period longer than 4 weeks). The purpose of this study is to verify the presence and eventually the magnitude of physiological cardiorespiratory changes in young team sport players after a period of long-term detraining. METHODS: Fourteen young soccer players (15 ± 1 year) were studied with two incremental tests at the end of the regular season and after a six-week total break period from training activities. Physiological variables were evaluated: heart rate (HR), oxygen uptake (VO2), volume of ventilation (VE), aerobic (VA) and anaerobic (Van) running speed at thresholds and maximum effort were recorded. RESULTS: This study shows the magnitude of the physiological changes in young players after a period of long-term detraining. The results showed significant decreases at the end of the detraining period of VO2 at VA of 22.7% (44.54 ± 4.56 vs. 34.41 ± 4.57 mL/kg/min, P<0.05), of 25.8% of VO2 at VAn (54.60 ± 5.81 vs. 40.48 ± 5.07 mL/kg/min, P<0.05) and of 21.2% in VO2 max (62.83 ± 5.77 vs. 49.46 ± 6.51 mL/kg/min, P<0.05). Speed at VA (11.5 ± 0.96 vs. 10.7 ± 0.97 km/h; P<0.05), speed at VAn (15.3 ± 1.05 vs. 14.2 ± 1.48 km/h; P<0.05), peak running speed (18.8 ± 1.20 vs. 17.2 ± 1.1 km/h; P<0.05). CONCLUSION: It is likely that alteration of metabolic parameters may significantly affect the range of physical condition and especially, aerobic-anaerobic resistance and maintenance training would be advisable in young athletes during the transition period. Given the relevance of worsening demonstrated by our data, coaches should avoid very long periods of complete rest (no more than 15 days) at the end of the season.

The use of noninvasive ventilation outside the intensive care unit: a clinical case report.

Noninvasive Ventilation (NIV) is one of the best weapon at our disposal to treat respiratory failure. The early use of NIV out of the Intensive Care Unit can improve patients' outcome. A 58-year-old man affected by severe bilateral pneumonia caused by Legionella Pneumophila was treated with Noninvasive Ventilation in extra Intensive Care Unit until the evidence of a marked improvement of clinical and radiological state.

Bilateral Visual Loss as Presenting Symptom of Posterior Reversible Encephalopathy Syndrome in a Patient with HIV/Tuberculosis Coinfection: A Case Report.

Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic state accompanied by a unique brain imaging pattern. This cliniconeuroradiological entity usually presents with visual disturbances (cortical blindness, homonymous hemianopia, visual neglect, and blurred vision) along with neurotoxic manifestations. Only a few cases of PRES have previously been reported in patients with advanced HIV disease. The authors describe a case of posterior reversible encephalopathy syndrome (PRES) in a patient with advanced HIV/TBC infection who developed a neurotoxic state following TB and ART therapy initiation. They present a comprehensive review of the literature and discuss the pathogenetic hypotheses.

Dynamic evaluation of renal resistive index in normoalbuminuric patients with newly diagnosed hypertension or type 2 diabetes.

AIM/HYPOTHESIS: Renal resistive index is a useful measure for quantifying alterations in renal blood flow. In the present study we evaluated resistive index at baseline and after vasodilation induced by nitroglycerine in normoalbuminuric patients with type 2 diabetes or essential hypertension, relating the values to indices of systemic vascular dysfunction. METHODS: Newly diagnosed treatment-naïve type 2 diabetic (n = 32) and hypertensive patients (n = 49) were compared with 27 age- and sex-matched healthy controls. Renal resistive index was obtained by duplex ultrasound at baseline and after 25 µg sublingual nitroglycerine. Endothelium-dependent (flow-mediated dilation) and -independent (response to nitroglycerine) vasodilation in the brachial artery was assessed by computerised edge detection system. Carotid-femoral pulse-wave velocity and augmentation index were assessed by applanation tonometry. Nitrotyrosine levels, an index of oxidative stress, were also measured. RESULTS: Resistive index was higher in diabetic than in hypertensive patients and controls (p < 0.001), while changes in resistive index induced by nitroglycerine were lower in hypertensive patients compared with controls (p < 0.01), and were further reduced in type 2 diabetic patients. Hypertensive and diabetic patients showed significantly increased arterial stiffness, nitrotyrosine levels and reduced endothelial function than controls (p < 0.05). Changes in resistive index induced by nitroglycerine were independently related to serum glucose, reactive hyperaemia and aortic pulse-wave velocity in the overall population. CONCLUSIONS/INTERPRETATION: These results support the dynamic evaluation of renal resistive index as an early detector of renal vascular alterations in the presence of type 2 diabetes and hypertension, even before the onset of microalbuminuria.

Pseudoaneurysm formation following intrasphenoid rupture of an idiopathic intracavernous carotid artery aneurysm: coil migration and early recurrence after endovascular treatment.

Intrasphenoid rupture of a non-traumatic aneurysm of the cavernous carotid artery is rare. We describe a patient in whom this condition manifested with epistaxis and led to the formation of a pseudoaneurysm occupying the right sphenoid sinus. The lesion recurred after repeated attempts at conservative endovascular therapy. Eventually the patient was treated with endovascular occlusion of the right internal carotid artery. Our report emphasizes the relapsing behaviour of a non-traumatic aneurysm of the cavernous portion of the internal carotid artery ruptured into the sphenoid sinus.

Ultrasound as a mechanical method for male dog contraception.

Therapeutic ultrasound (1.5 W/cm(2)) was investigated for its effect upon testicular size and consistency and semen quality in five dogs. Dogs were treated every other day with a total of three treatments and were examined up to 2 weeks after treatment. There was some tenderness after treatment and a significant decrease in testicular size and semen quality. This method may provide a suitable contraception technique in dogs and requires further investigation.

Endocytoscopy can identify dysplasia in aberrant crypt foci of the colorectum: a prospective in vivo study.

BACKGROUND AND STUDY AIM: A catheter-type endocytoscope has recently been developed that is able to provide in vivo cellular images of gastrointestinal mucosa. Aberrant crypt foci (ACF) represent the earliest precursor of colorectal cancer featuring the dysplasia-carcinoma sequence. The aim of the current study was to assess the potential of the endocytoscopy system (ECS) in the "in vivo" detection of dysplasia in colorectal ACF. PATIENTS AND METHODS: Consecutive patients with colorectal ACF were studied with endocytoscopy. Blinded endoscopic and histological assessments were obtained. Lesions were excised en bloc for histology. RESULTS: A total of 48 colorectal lesions were examined in 41 patients. The mean duration of the ECS procedure was 44 +/- 12 minutes (range 31 - 62 minutes). The quality of ECS images was rated as good in 39/48, medium in six, and poor in three (6.2 %). It was possible to observe lesions at the cellular level and evaluate both cellular and structural atypia in vivo. In normal mucosa, crypts had preserved individuality and round-shaped contours. Nuclei were located at the basal third of the crypt in a single line, and the lumen was circular. In dysplastic ACF, crypt contours were polygonal, cell nuclei were elongated with pseudostratification toward the luminal half of the crypt and irregularly arranged, and the lumen was linear. In all, 23 endocytoscopic images were labeled as dysplastic and 25 as nondysplastic. Histology confirmed low-grade dysplasia in 21/23 cases (91.4 % sensitivity). Absence of dysplasia was confirmed in the remaining 25 cases (100 % specificity). Interobserver agreement between trained endoscopist and pathologist was good (wK 0.68; 95 % CI 0.59 - 0.78). CONCLUSIONS: Endocytoscopy provides real-time histological images in vivo, with clear visualization of cellular details and features of dysplasia in colorectal ACF.

A case of aneurysm on a persistent hypoglossal artery treated by endovascular coiling.

SUMMARY: We describe a 22-year-old woman admitted to hospital in emergency with nuchal headache and vomiting. CT scan disclosed subarachnoid hemorrhage. Digital subtraction angiography with three-dimensional rotational acquisitions showed a ruptured aneurysm of a right persistent primitive hypoglossal artery as the cause of symptoms and hemorrhage. The patient was successfully treated with endovascular coiling of the aneurysm. This is the second literature report describing endovascular treatment in this unusual condition.

Clinical Features and Classification of Brain AVMs and Cranial DAVFs.

The clinical findings of intracranial vascular malformations are strictly related to their morphologic, angioarchitectural and hemodynamic characteristics. An overall study of these features is the first step to understand the different classifications for arteriovenous malformations, dural arteriovenous fistulas and carotid-cavernous fistulas. This evaluation will also suggest the correct timing of endovascular treatment and which part of the lesion should be the target of the therapy. Conventional cerebral angiography is mandatory when a correct classification of intracranial arteriovenous malformative shunts must be achieved. The angioarchitectural classification of brain arteriovenous malformations considers all angiographic features of each component of the malformation, both morphologically and hemodynamically, and relates them to the clinical course of the disease. The correlation between clinical findings, angiographic features and classifications is even stronger for cranial dural arteriovenous fistulas, in which cortical venous drainage is typical of "aggressive" fistulas and is usually absent in the "benign" type. Similarly, carotid-cavernous fistulas can be differentiated at angiography into high or low flow lesions according to the flow rate of the shunt, and into direct or indirect fistulas, according to the origin of arterial feeders. This paper focuses on the existing relation between the hemodynamics of brain arteriovenous malformations, cranial dural arteriovenous fistulas, carotid-cavernous fistulas, and their most frequent clinical findings, through an analysis of the most widely used different classification systems.

Radiofrequency catheter ablation in drug refractory maternal supraventricular tachycardias in advanced pregnancy.

BACKGROUND: Treatment of maternal tachyarrhythmias in pregnancy is a major clinical issue. Pharmacological treatment raises important concerns regarding partial efficacy and side effects. Radiofrequency ablation of arrhythmogenic substrate has rarely been performed during pregnancy because of the fetal risks related to x-ray exposure and potential fetomaternal procedural complications. CASES: Three women affected by supraventricular tachycardias refractory to pharmacological therapy underwent successful radiofrequency catheter ablation at 29 to 30 weeks' pregnancy. All patients had cesarean delivery of newborns with normal Apgar scores. CONCLUSION: Radiofrequency catheter ablation is an effective treatment of drug refractory maternal supraventricular tachycardias in advanced pregnancy. Further studies are required to establish its long-term fetal safety.

Atrial electroanatomic remodeling after circumferential radiofrequency pulmonary vein ablation: efficacy of an anatomic approach in a large cohort of patients with atrial fibrillation.

BACKGROUND: Circumferential radiofrequency ablation around pulmonary vein (PV) ostia has recently been described as a new anatomic approach for atrial fibrillation (AF). METHODS AND RESULTS: We treated 251 consecutive patients with paroxysmal (n=179) or permanent (n=72) AF. Circular PV lesions were deployed transseptally during sinus rhythm (n=124) or AF (n=127) using 3D electroanatomic guidance. Procedures lasted 148+/-26 minutes. Among 980 lesions surrounding individual PVs (n=956) or 2 ipsilateral veins with close openings or common ostium (n=24), 75% were defined as complete by a bipolar electrogram amplitude <0.1 mV inside the lesion and a delay >30 ms across the line. The amount of low-voltage encircled area was 3594+/-449 mm(2), which accounted for 23+/-9% of the total left atrial (LA) map surface. Major complications (cardiac tamponade) occurred in 2 patients (0.8%). No PV stenoses were detected by transesophageal echocardiography. After 10.4+/-4.5 months, 152 patients with paroxysmal AF (85%) and 49 with permanent AF (68%) were AF-free. Patients with and without AF recurrence did not differ in age, AF duration, prevalence of heart disease, or ejection fraction, but the LA diameter was significantly higher (P<0.001) in permanent AF patients with recurrence. The proportion of PVs with complete lesions was similar between patients with and without recurrence, but the latter had larger low-voltage encircled areas after radiofrequency (expressed as percent of LA surface area; P<0.001). CONCLUSIONS: Circumferential PV ablation is a safe and effective treatment for AF. Its success is likely due to both PV trigger isolation and electroanatomic remodeling of the area encompassing the PV ostia.

[Prospects of the treatment of atrial fibrillation. Circumferential radiofrequency ablation of pulmonary vein ostia]. / Prospettive nel trattamento della fibrillazione atriale. L'ablazione circonferenziale in radiofrequenza degli osti delle vene polmonari.

The dominance of the left atrium (LA) in the pulmonary vein (PV) regions for triggering and maintaining atrial fibrillation (AF) is now widely recognized. Radiofrequency (RF) PV isolation with electroanatomical guidance has recently emerged as a promising approach for AF treatment. We report the clinical outcome of the procedure in 251 consecutive patients with paroxysmal (n = 179) or permanent (n = 72) AF. Circular RF lesions were deployed transseptally during sinus rhythm or AF at 5 mm from PV ostia. Procedural and mapping times were 112 +/- 32 min and 75 +/- 27 min, respectively, with 29 +/- 11 min of fluoroscopy. Complete lesions (peak-to-peak bipolar electrogram amplitude < 0.1 mV inside the line and no double potentials) were achieved in 85% of the veins treated. Sinus rhythm was restored during RF delivery in 52% and by DC shock in the remaining. Major complications (cardiac tamponade) occurred in 3%. Extent of ablated area was 4.9 +/- 0.5 cm2, accounting for 28 +/- 9% of the total LA map surface. After 11 +/- 5 months, procedure success rates (freedom from AF without antiarrhythmic drugs) were 85% for paroxysmal and 68% for permanent AF. No PV stenoses were detected. By univariate analysis, an increased risk of recurrence was predicted by LA dilation (diameter > 50 mm), AF duration, and a low ablated area (< 15% of total LA surface). After adjustment, only the latter variable continued to be significant (odds ratio 3.5, 95% confidence interval, 1.6-5.8). In conclusion, RF PV isolation is safe and effective in either paroxysmal or permanent AF. Patients with enlarged left atrium may require wider lesions to achieve AF suppression.

Gene correction of integrin beta4-dependent pyloric atresia-junctional epidermolysis bullosa keratinocytes establishes a role for beta4 tyrosines 1422 and 1440 in hemidesmosome assembly.

The cytoplasmic domain of beta4 integrin contains two pairs of fibronectin-like repeats separated by a connecting segment. The connecting segment harbors a putative tyrosine activation motif in which tyrosines 1422 and 1440 are phosphorylated in response to alpha6beta4 binding to laminin-5. Primary beta4-null keratinocytes, obtained from a newborn suffering from lethal junctional epidermolysis bullosa, were stably transduced with retroviruses carrying a full-length beta4 cDNA or a beta4 cDNA with phenylalanine substitutions at Tyr-1422 and Tyr-1440. Hemidesmosome assembly was evaluated on organotypic skin cultures. beta4-corrected keratinocytes were indistinguishable from normal cells in terms of alpha6beta4 expression, the localization of hemidesmosome components, and hemidesmosome structure and density, suggesting full genetic and functional correction of beta4-null keratinocytes. In cultures generated from beta4(Y1422F/Y1440F) keratinocytes, beta4 mutants as well as alpha6 integrin, HD1/plectin, and BP180 were not concentrated at the dermal-epidermal junction. Furthermore, the number of hemidesmosomes was strikingly reduced as compared with beta4-corrected keratinocytes. The rare hemidesmosomes detected in beta4(Y1422F/Y1440F) cells were devoid of sub-basal dense plates and of inner cytoplasmic plaques with keratin filament insertion. Collectively, our data demonstrate that the beta4 tyrosine activation motif is not required for the localization of alpha6beta4 at the keratinocyte plasma membrane but is essential for optimal assembly of bona fide hemidesmosomes.