Symptomatic mucosal involvement in pachyonychia congenita: challenges in infants and young children

BACKGROUND

Pachyonychia congenita (PC) is a rare autosomal dominant genodermatosis caused by a mutation in any one of five keratin genes (KRT6A, KRT6B, KRT6C, KRT16 or KRT17). Characteristic features of PC are painful palmoplantar keratoderma, variable nail dystrophy, cysts, follicular hyperkeratosis and often oral leukokeratosis. Although oral leukokeratosis can go unnoticed, mucosal involvement of the oral cavity and upper airways can manifest with pain during feeding, hoarseness, stridor and, occasionally, life-threatening obstruction.

OBJECTIVES

To characterize patients with PC with symptomatic mucosal involvement.

METHODS

We present a case series of nine children with PC with symptomatic mucosal involvement, all with heterozygous mutations in KRT6A. Seven patients complained of painful feeding problems. Four patients were diagnosed with failure to thrive, three of whom required a feeding tube. Simple feeding solutions were beneficial in most cases. Seven patients had laryngeal involvement and one patient died at 4 years of age from acute laryngeal obstruction.

CONCLUSIONS

It is important for dermatologists and otolaryngologists to be aware that symptomatic mucosal involvement, and very rarely laryngeal obstruction, can occur in patients with PC. Usually simple feeding solutions may prevent complications and failure to thrive. What's already known about this topic? Pachyonychia congenita (PC) is a rare autosomal dominant genodermatosis due to a mutation in any one of five keratin genes. Symptomatic mucosal involvement is an important clinical feature of PC and appears to be more pronounced in KRT6A mutation carriers. Only leukokeratosis is frequently seen in PC and can be one of the earliest signs of disease. Laryngeal involvement is a less common feature. It might be symptomatic but usually presents as hoarseness, stridor and, occasionally, as a life-threatening respiratory distress. What does this study add? In most cases of laryngeal involvement, there is no need for any intervention. Although pain and feeding difficulties are usually attributed to the oral leukokeratosis, they can be related to a phenomenon called 'first bite syndrome' (FBS). Symptomatic mucosal involvement with feeding difficulty is important but can be managed in most cases with simple feeding solutions (e.g. softer nipple with a larger hole, thicker formula and feeding with a syringe). Linked Comment: Youssefian and Vahidnezhad. Br J Dermatol 2020; 182:536-537.

Genetic variants in pachyonychia congenita-associated keratins increase susceptibility to tooth decay

Pachyonychia congenita (PC) is a cutaneous disorder primarily characterized by nail dystrophy and painful palmoplantar keratoderma. PC is caused by mutations in KRT6A, KRT6B, KRT6C, KRT16, and KRT17, a set of keratin genes expressed in the nail bed, palmoplantar epidermis, oral mucosal epithelium, hair follicle and sweat gland. RNA-seq analysis revealed that all PC-associated keratins (except for Krt6c that does exist in the mouse genome) are expressed in the mouse enamel organ. We further demonstrated that these keratins are produced by ameloblasts and are incorporated into mature human enamel. Using genetic and intraoral examination data from 573 adults and 449 children, we identified several missense polymorphisms in KRT6A, KRT6B and KRT6C that lead to a higher risk for dental caries. Structural analysis of teeth from a PC patient carrying a p.Asn171Lys substitution in keratin-6a (K6a) revealed disruption of enamel rod sheaths resulting in altered rod shape and distribution. Finally, this PC-associated substitution as well as more frequent caries-associated SNPs, found in two of the KRT6 genes, that result in p.Ser143Asn substitution (rs28538343 in KRT6B and rs151117600 in KRT6C), alter the assembly of K6 filaments in ameloblast-like cells. These results identify a new set of keratins involved in tooth enamel formation, distinguish novel susceptibility loci for tooth decay and reveal additional clinical features of pachyonychia congenita.

Tooth decay, more commonly known as dental cavities, is the most common chronic disease worldwide, both in children and in adults. It consists in the destruction of tooth enamel, the outer layer of the teeth, by acid-producing bacteria. Enamel is the hardest tissue in the body, comprised of 96% minerals. However, it contains a small fraction of proteins that is important for its resistance to mechanical stress and decay. Here we show that this protein fraction contains a set of structural proteins (K6a, K6b, K6c, K16 and K17) that belong to the keratin family and are present specifically in the skin of the palms and soles, as well as in nails. We further show that common genetic mutations that affect the composition of these proteins lead to an increased number of cavities. Rare mutations in these keratins lead to a human disease called pachyonychia congenita (PC) and characterized by severe nail malformations and lesions in the skin of the palms and soles. Analysis of wisdom teeth from one of these patients showed that their enamel exhibited structural defects. These results demonstrate that these keratins are important components of tooth enamel and that common genetic variants in the genes that encode them influence tooth decay risk in the general population.

Proteomic profiling of Pachyonychia congenita plantar callus

Callus samples from the ball and the arch of the foot, collected on tape circles, were compared by shotgun proteomic profiling. Pachyonychia congenita subjects were sampled who exhibited a mutation in KRT6A, KRT6B, KRT6C, KRT16 or KRT17, and the proteins were digested and analyzed by tandem mass spectrometry. In comparison with samples from unaffected control subjects, those from subjects with KRT6A or KRT16 mutations displayed the most differences in profile from normal, while those from subjects with KRT6C or KRT17 mutations showed few differences from normal. The profiles from subjects with KRT6B mutations were intermediate in protein profile differences. Degree of departure from the normal profile could be estimated by expression of numerous proteins in callus from the ball of the foot that were consistently different. By contrast, the protein profile from the arch of the foot was hardly affected. The results provide a foundation for noninvasive monitoring of the efficacy of treatments with quantitative assessment of departure from the normal phenotype.

SIGNIFICANCE

Pachyonychia congenita is an orphan disease in which the connection between the basic defect (keratin mutation) and debilitating symptoms (severe plantar pain) is poorly understood. Present work addresses the degree to which the protein profile is altered in the epidermis where the severe pain originates. The results indicate that the mutated keratins differ greatly in the degree to which they elicit perturbations in protein profile. In those cases with markedly altered protein levels, monitoring the callus profile may provide an objective measure of treatment efficacy.

Mutations in desmoglein 1 cause diverse inherited palmoplantar keratoderma phenotypes: implications for genetic screening

The inherited palmoplantar keratodermas (PPKs) are a heterogeneous group of genodermatoses, characterized by thickening of the epidermis of the palms and soles. No classification system satisfactorily unites clinical presentation, pathology and molecular pathogenesis. There are four patterns of hyperkeratosis - striate, focal, diffuse and punctate. Mutations in the desmoglein 1 gene (DSG1), a transmembrane glycoprotein, have been reported primarily in striate, but also in focal and diffuse PPKs. We report seven unrelated pedigrees with dominantly inherited PPK owing to mutations in the DSG1 gene, with marked phenotypic variation. Genomic DNA from each family was isolated, and individual exons amplified by polymerase chain reaction. Sanger sequencing was employed to identify mutations. Mutation analysis identified novel mutations in five families (p.Tyr126Hisfs*2, p.Ser521Tyrfs*2, p.Trp3*, p.Asp591Phefs*9 and p.Met249Ilefs*6) with striate palmar involvement and varying focal or diffuse plantar disease, and the recurrent mutation c.76C>T, p.Arg26*, in two families with variable PPK patterns. We report one recurrent and five novel DSG1 mutations, causing varying patterns of PPK, highlighting the clinical heterogeneity arising from mutations in this gene.

Keratin 17 Mutations in Four Families from India with Pachyonychia Congenita

Pachyonychia congenita (PC) is a rare autosomal dominant genetic skin disorder due to a mutation in any one of the five keratin genes, KRT6A, KRT6B, KRT6C, KRT16, or KRT17. The main features are palmoplantar keratoderma, plantar pain, and nail dystrophy. Cysts of various types, follicular hyperkeratosis, oral leukokeratosis, hyperhidrosis, and natal teeth may also be present. Four unrelated Indian families presented with a clinical diagnosis of PC. This was confirmed by genetic testing; mutations in KRT17 were identified in all affected individuals.

Gene expression profiling in pachyonychia congenita skin

BACKGROUND

Pachyonychia congenita (PC) is a skin disorder resulting from mutations in keratin (K) proteins including K6a, K6b, K16, and K17. One of the major symptoms is painful plantar keratoderma. The pathogenic sequelae resulting from the keratin mutations remain unclear.

OBJECTIVE

To better understand PC pathogenesis.

METHODS

RNA profiling was performed on biopsies taken from PC-involved and uninvolved plantar skin of seven genotyped PC patients (two K6a, one K6b, three K16, and one K17) as well as from control volunteers. Protein profiling was generated from tape-stripping samples.

RESULTS

A comparison of PC-involved skin biopsies to adjacent uninvolved plantar skin identified 112 differentially-expressed mRNAs common to patient groups harboring K6 (i.e., both K6a and K6b) and K16 mutations. Among these mRNAs, 25 encode structural proteins including keratins, small proline-rich and late cornified envelope proteins, 20 are related to metabolism and 16 encode proteases, peptidases, and their inhibitors including kallikrein-related peptidases (KLKs), and serine protease inhibitors (SERPINs). mRNAs were also identified to be differentially expressed only in K6 (81) or K16 (141) patient samples. Furthermore, 13 mRNAs were identified that may be involved in pain including nociception and neuropathy. Protein profiling, comparing three K6a plantar tape-stripping samples to non-PC controls, showed changes in the PC corneocytes similar, but not identical, to the mRNA analysis.

CONCLUSION

Many differentially-expressed genes identified in PC-involved skin encode components critical for skin barrier homeostasis including keratinocyte proliferation, differentiation, cornification, and desquamation. The profiling data provide a foundation for unraveling the pathogenesis of PC and identifying targets for developing effective PC therapeutics.

PCQoL

Background:

Pachyonychia congenita (PC) is a rare but often debilitating, dominantly inherited disorder. New treatments require more accurate instruments for evaluating changes in the quality of life in these patients.

Objectives:

This study was undertaken to develop and validate a quality of life questionnaire for PC patients (PCQoL).

Methods:

Relevant factors influencing quality of life in PC patients were identified and incorporated into the well-recognized, general questionnaire, the Dermatology Life Quality Index (DLQI), to establish a disease-specific measure, the PCQoL. Classical test theory (CTT) and Rasch analysis (RA) were used to analyze and validate the PCQoL.

Results:

CTT analysis established test–retest reliability and internal consistency for the PCQoL. Concurrent and construct validity for the DLQI and the PCQoL were also validated. Chi-square–based infit and outfit statistics indicated that the Rasch model fits the observed responses very well. RA reconfirmed reliability, internal consistency, reasonable homogeneity, construct validity, and the presence of three RA-based domains.

Conclusion:

The PCQoL questionnaire is a measure validated by both CTT and RA. It appears to be a valuable tool in measuring quality of life modifications in PC individuals with keratoderma.

Pachyonychia congenita cornered: report on the 11th Annual International Pachyonychia Congenita Consortium Meeting

This is a report of the research presented at the 11th Annual Meeting of the International Pachyonychia Congenita Consortium, held on 6 May 2014 in Albuquerque, NM, U.S.A. This year's meeting was divided into five corners concerning pachyonychia congenita (PC) research: (i) 'PC Pathogenesis Cornered', an overview of recent keratin research, for PC and other skin disorders; (ii) 'From All Corners of …', an outline of other genetic disorders that we can learn from; (iii) 'Fighting For Our Corner', an outline of National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases programmes and U.S. funding opportunities applicable to rare skin disorders; (iv) 'The PC Corner', focusing on recent clinical studies related to PC; and (v) 'Clinical Corners: Turning the Corner?', an update on ongoing PC clinical trials.

Pathogen-inspired drug delivery to the central nervous system

For as long as the human blood-brain barrier (BBB) has been evolving to exclude bloodborne agents from the central nervous system (CNS), pathogens have adopted a multitude of strategies to bypass it. Some pathogens, notably viruses and certain bacteria, enter the CNS in whole form, achieving direct physical passage through endothelial or neuronal cells to infect the brain. Other pathogens, including bacteria and multicellular eukaryotic organisms, secrete toxins that preferentially interact with specific cell types to exert a broad range of biological effects on peripheral and central neurons. In this review, we will discuss the directed mechanisms that viruses, bacteria, and the toxins secreted by higher order organisms use to enter the CNS. Our goal is to identify ligand-mediated strategies that could be used to improve the brain-specific delivery of engineered nanocarriers, including polymers, lipids, biologically sourced materials, and imaging agents.

The molecular genetic analysis of the expanding pachyonychia congenita case collection

BACKGROUND

Pachyonychia congenita (PC) is a rare autosomal dominant keratinizing disorder characterized by severe, painful, palmoplantar keratoderma and nail dystrophy, often accompanied by oral leucokeratosis, cysts and follicular keratosis. It is caused by mutations in one of five keratin genes: KRT6A, KRT6B, KRT6C, KRT16 or KRT17.

OBJECTIVES

To identify mutations in 84 new families with a clinical diagnosis of PC, recruited by the International Pachyonychia Congenita Research Registry during the last few years.

METHODS

Genomic DNA isolated from saliva or peripheral blood leucocytes was amplified using primers specific for the PC-associated keratin genes and polymerase chain reaction products were directly sequenced.

RESULTS

Mutations were identified in 84 families in the PC-associated keratin genes, comprising 46 distinct keratin mutations. Fourteen were previously unreported mutations, bringing the total number of different keratin mutations associated with PC to 105.

CONCLUSIONS

By identifying mutations in KRT6A, KRT6B, KRT6C, KRT16 or KRT17, this study has confirmed, at the molecular level, the clinical diagnosis of PC in these families.

Observation of measurement-induced entanglement and quantum trajectories of remote superconducting qubits

The creation of a quantum network requires the distribution of coherent information across macroscopic distances. We demonstrate the entanglement of two superconducting qubits, separated by more than a meter of coaxial cable, by designing a joint measurement that probabilistically projects onto an entangled state. By using a continuous measurement scheme, we are further able to observe single quantum trajectories of the joint two-qubit state, confirming the validity of the quantum Bayesian formalism for a cascaded system. Our results allow us to resolve the dynamics of continuous projection onto the entangled manifold, in quantitative agreement with theory.

Report of the 10th Annual International Pachyonychia Congenita Consortium Meeting

The International Pachyonychia Congenita Consortium (IPCC) was founded in 2004 in Park City, Utah, USA. Its goal is to find a cure for pachyonychia congenita, a rare keratinizing disorder. From February 14th–17th, 2013, the group convened in Park City for their tenth annual meeting. The 2013 meeting focused on how to best move forward with clinical trials and on learning from work in other scientific areas, with an emphasis on understanding mechanisms of pain and hyperkeratosis. Considerable time was spent on discussing the best way to move forward with development of new treatments and how to obtain or develop tools that can measure treatment outcomes in PC.

Impact of liver fibrosis on prognosis following liver resection for hepatitis B-associated hepatocellular carcinoma

BACKGROUND

This study aims to evaluate the impact of liver fibrosis severity on prognosis following liver resection among HBV-HCC patients.

METHODS

Data were extracted from a prospective database of 189 HBV-HCC patients treated at Mount Sinai between 1995 and 2008. Fibrosis staging of each surgical resection specimen using the modified Ishak method was performed by a single liver pathologist.

RESULTS

A wide range of Ishak fibrosis stage was observed among this patient population, with 29% having established cirrhosis (Ishak stage 6). Ishak stage 6 was independently associated with poor overall and recurrence-free survival. In patients with Ishak stage 1-5, Ishak stage did not affect survival; rather, tumour size was associated with poor overall survival, and tumour size, histologic activity index and serum AFP>20 ng ml(-1) were associated with poor recurrence-free survival. In patients with Ishak stage 6, poorly differentiated histology and tumour size were associated with poor overall survival, and tumour size was associated with poor recurrence-free survival.

CONCLUSION

HBV-HCC develops with varying degrees of underlying liver fibrosis; however, progressive liver fibrosis does not affect the outcomes following resection until cirrhosis is reached. Established cirrhosis, as defined histologically by Ishak stage 6, is an independent predictor of poor overall and recurrence-free survival among these patients.

Comparative study of high-resolution multifrequency ultrasound of the plantar skin in patients with various types of hereditary palmoplantar keratoderma

BACKGROUND

High-variable-frequency ultrasound is used as an imaging tool for various cutaneous disorders. We utilized this tool in pachyonychia congenita (PC) patients, who typically present with plantar hyperkeratosis and often severely debilitating pain, compared to patients with epidermolytic palmoplantar keratoderma (EPPK) and mal de Meleda (MDM).

OBJECTIVE

To ascertain the feasibility of ultrasound technology for the diagnosis of PC.

METHODS

The study included a total of 16 patients, 7 with PC, 5 with EPPK and 4 with MDM, who underwent ultrasound examination of the plantar skin with high-resolution multifrequency ultrasound equipment.

RESULTS

Ultrasound scans performed over the proximal and distal plantar foot calluses in PC patients demonstrated hyperechoic dots and lines within the epidermis compatible with hyperkeratosis, engorged varicose veins in the dermis and an anechoic layer interposed between the epidermis and the dermis, corresponding to blister fluid below the calluses. In contrast to PC patients, patients with MDM and EPPK demonstrated no blisters.

CONCLUSION

PC patients, as opposed to a group of patients with MDM and EPPK, displayed subepidermal blistering beneath their calluses. This finding may help in the diagnosis of PC and in partially explaining plantar pain as part of PC symptomatology.

Best treatment practices for pachyonychia congenita

BACKGROUND

Numerous therapeutic modalities have been proposed to treat the manifestations of pachyonychia congenita (PC). While research hopes lie with molecular therapies, patients are in need of answers regarding the efficacy of conventional treatments.

AIM OF THE STUDY

To determine patients' experience and preferences regarding conventional treatments for PC.

METHODS

The study population included 120 PC patients from 20 countries. The study was based on a patient survey developed by physicians and researchers from the International Pachyonychia Congenita Consortium and conducted via the internet. Using an effectiveness scale of 1 to 5, the patients were asked to grade treatments for different manifestations, including keratoderma, cysts, follicular hyperkeratosis, fingernail and toenail involvement.

RESULTS

Patients reported surgical treatments being most effective for cysts and mechanical treatments the most effective conventional therapeutic approach for all other investigated manifestations. The other conventional medical treatments were found to be non-effective to only slightly effective. Among patients with keratoderma, older people were more likely to report beneficial effect from mechanical treatments (P = 0.04), topical retinoids (P = 0.04) and topical steroids (P = 0.02). Likewise, females were more inclined to report filing and grinding beneficial than males (P = 0.02). Finally, carriers of KRT16 and KRT6a were more likely to benefit from keratolytics than carriers of mutations in KRT17 (P = 0.04).

CONCLUSIONS

None of the currently available therapeutic options for PC are ideal, although they provide some relief, with mechanical/surgical options being preferred over medical therapies. These results emphasize the need for more efficient and targeted therapies.

New immunosuppressive agents for maintenance therapy in organ transplantation

Traditional cyclosporin-based immunosuppressive protocols are associated with relatively high incidences of early acute rejection and late graft loss due to chronic rejection. In addition, long-term immunosuppression with cyclosporin and corticosteroids has been associated with significant metabolic, infectious, malignant and cosmetic adverse effects. In the last decade, the goals of immunosuppression strategies have included not only short-term survival but also graft acceptance, with a low incidence of early acute rejection and minimal long-term toxicity. Tacrolimus and mycophenolate mofetil are 2 new immunosuppressive agents that have recently been approved for use. The mechanism of action and toxicity profile of tacrolimus are similar to that of cyclosporin. Tacrolimus reduces early acute rejection and is also effective in salvage of allografts with refractory rejection. A wide spectrum of adverse effects, including nephrotoxic, neurotoxic, gastrointestinal, metabolic and hematological effects, has been reported in association with tacrolimus but, unlike cyclosporin, this agent is not associated with hirsutism or gingival hyperplasia. Mycophenolate mofetil, an antimetabolite, has been effective in reducing early acute rejection and in treatment of refractory rejection when used in combination with cyclosporin instead of azathioprine. Its myelosuppressive and gastrointestinal toxicities are mild and reversible, but it may be associated with an increased risk of infections. Both agents permit early corticosteroid withdrawal. Other new immunosuppressive agents that act on different stages of the cell cycle but that have not yet been introduced for wide clinical use, including sirolimus (rapamycin), brequinar, mizoribine and gusperimus, are also discussed in this review.

Interaction-induced shift of the cyclotron resonance of graphene using infrared spectroscopy

We report a study of the cyclotron resonance (CR) transitions to and from the unusual n=0 Landau level (LL) in monolayer graphene. Unexpectedly, we find the CR transition energy exhibits large (up to 10%) and nonmonotonic shifts as a function of the LL filling factor, with the energy being largest at half filling of the n=0 level. The magnitude of these shifts, and their magnetic field dependence, suggests that an interaction-enhanced energy gap opens in the n=0 level at high magnetic fields. Such interaction effects normally have a limited impact on the CR due to Kohn's theorem [W. Kohn, Phys. Rev. 123, 1242 (1961)], which does not apply in graphene as a consequence of the underlying linear band structure.

Outcome for patients treated with laparoscopic versus open resection of hepatocellular carcinoma: case-matched analysis

INTRODUCTION

This is a case-matched analysis of patients undergoing laparoscopic versus open hepatectomy for hepatocellular carcinoma (HCC), with specific regard to margin status and survival.

METHODS

Laparoscopic cases were matched with open controls by cirrhosis and tumor size (within 10%). Data were evaluated by logistic regression using the generalized estimating equation method. Mixed linear regression models were used to assess operative duration in the groups. Overall and disease-free survival were compared using a Cox proportional frailty model.

RESULTS

Twenty laparoscopic cases were matched to 56 open resections. Thirty patients (39%) developed recurrence and 13 patients (17%) died, including one (1.3%) death within 30 days. There were no significant differences in age, gender, cirrhosis or tumor size. Paired univariate and multivariate analyses showed cases of laparoscopic resection had similar rates of transfusion and positive margins compared with open resection. Operative duration was similar in laparoscopic (mean 161 +/- 37 min) and open (mean 165 +/- 53 min) groups. The adjusted odds of length of stay > or = 6 days was significantly lower in patients with laparoscopic resection [odds ratio (OR) = 0.07, 95% confidence interval (CI) = 0.02-0.27]. Both unadjusted and adjusted analyses showed no significant association between type of resection and overall or disease-free survival.

DISCUSSION

Neither margin status, nor recurrence, nor survival was significantly different between the two cohorts. Laparoscopic resection for malignancy is safe, with a similar operative time as open hepatectomy. If tumor location is amenable, laparoscopic resection for HCC is a reasonable alternative to open resection with the added benefits of improved cosmesis and sooner discharge home.

The Mount Sinai experience with orthotopic liver transplantation for benign tumors: brief report and literature review: case reports

Orthotopic liver transplantation (OLT) is performed for benign hepatic lesions that are symptomatic, too large to be resected, have a malignant transformation potential, cause debilitating/life-threatening manifestations, or in patients experiencing posthepatectomy acute liver failure. Among benign tumors, polycystic liver disease (PLD) is the most common indication for OLT alone, or combined liver-kidney transplantation. Our 10-year experience with OLT for benign tumors includes two patients with PLD and one with a benign giant fibrous tumor. In this report, we present our experience with OLT for benign liver tumors, commenting on relevant published studies.

Effect of ischemia-reperfusion on the incidence of acute cellular rejection and timing of histologic hepatitis C virus recurrence after liver transplantation

BACKGROUND

Because of a critical shortage of deceased donor (DD) livers, more extended criteria allografts are being utilized; these allografts are at increased risk for ischemia-reperfusion injury (IRI). We assessed whether, in a large cohort of patients transplanted for hepatitis C virus (HCV) either via a DD or live donor (LD), there was a relationship between the degree of IRI and the frequency and timing of acute cellular rejection (ACR) and histologic HCV recurrence.

METHODS

During an 8-year study, patients were separated into four groups based on peak alanine aminotransferase (ALT) levels and three groups based on severity of IRI on postreperfusion liver biopsy.

RESULTS

The mean follow-up time of 433 DD and 44 LD recipients was 1212 days. We noted a strong correlation in DD between peak ALT and the histologic degree of IRI (P = .01). There was no difference in the incidence or grade of ACR among the four groups. There was no correlation between the severity of IRI and the incidence or time to histologic recurrence of HCV.

CONCLUSIONS

The magnitude of peak ALT correlated with the severity of IRI on postreperfusion liver biopsy. Among this large HCV cohort, there was no correlation between the severity of IRI and the incidence or timing of histologic HCV recurrence or incidence of ACR.

Synthesis of oligoribonucleotides using the 2-nitrobenzyloxymethyl group for 2'-hydroxyl protection

RNA can be rapidly synthesized using protected ribonucleoside phosphoramidite monomers that carry 2-nitrobenzyloxymethyl groups on their 2-hydroxyls. These protecting groups are removed from the oligoribonucleotide products by exposure to long-wave UV light.

Cyclotron resonance in bilayer graphene

We present the first measurements of cyclotron resonance of electrons and holes in bilayer graphene. In magnetic fields up to B=18 T, we observe four distinct intraband transitions in both the conduction and valence bands. The transition energies are roughly linear in B between the lowest Landau levels, whereas they follow square root[B] for the higher transitions. This highly unusual behavior represents a change from a parabolic to a linear energy dispersion. The density of states derived from our data generally agrees with the existing lowest order tight binding calculation for bilayer graphene. However, in comparing data to theory, a single set of fitting parameters fails to describe the experimental results.

Chemical reaction fronts in ordered and disordered cellular flows with opposing winds

We present experiments on the motion of chemical fronts in ordered and disordered vortex flows with imposed uniform winds. Fronts in a chain of alternating vortices are found to freeze (pin to the separatrix) for a wide range of opposing winds that grows nonlinearly with the characteristic strength of the underlying vorticity. Experiments in spatially disordered flows demonstrate that freezing of fronts is common to cellular flows; furthermore, it is not dependent on boundary conditions. We therefore anticipate similar pinning in a wide range of 2D cellular flows and front-producing systems.

Infrared spectroscopy of Landau levels of graphene

We report infrared studies of the Landau level (LL) transitions in single layer graphene. Our specimens are density tunable and show in situ half-integer quantum Hall plateaus. Infrared transmission is measured in magnetic fields up to B=18 T at selected LL fillings. Resonances between hole LLs and electron LLs, as well as resonances between hole and electron LLs, are resolved. Their transition energies are proportional to sqrt[B], and the deduced band velocity is (-)c approximately equal to 1.1 x 10(6) m/s. The lack of precise scaling between different LL transitions indicates considerable contributions of many-particle effects to the infrared transition energies.

Noninvasive preoperative evaluation of biliary anatomy in right-lobe living donors with mangafodipir trisodium-enhanced MR cholangiography

BACKGROUND

Accurate preoperative radiologic imaging is essential to assess the vascular and biliary anatomy of right-lobe living donors and to ensure their safety. Volumetric magnetic resonance cholangiography (MRCP) using Mangafodipir trisodium (Mn-DPDP) contrast has been recently proposed to evaluate the biliary anatomy of living donor candidates.

METHODS

During their preoperative evaluation, 18 right-lobe (RL) living donors underwent 3D Mn-DPDP-enhanced MRCP in addition to the standard thin- and thick-slab MRCP imaging. Immediately prior to hepatectomy all 18 RL donors underwent intraoperative cholangiography (IOC) via the cystic duct. We compared the efficacy of these different radiologic techniques to actual intraoperative IOC findings.

RESULTS

Sixty-eight intrahepatic bile ducts were identified on IOC, 67(98.5%) by Mn-DPDP-enhanced 3D MRCP, 41 (60%) by thick-slab SSFSE imaging, and 35 (51%) by thin-slice SSFSE imaging. Mn-DPDP-enhanced 3D MRCP detected 100% (n = 5) of the anomalous origins of the right bile duct, and thick-slab MRCP detected 20% (n = 1) and thin-slab MRCP detected 0%. Anterior and posterior right intrahepatic bile ducts were identified by MnDPDP-enhanced 3D MRCP 100% of the time, by thick-slab SSFSE imaging 35% of the time, and by thin-slice SSFSE imaging only 12% of the time.

CONCLUSIONS

Mn-DPDP-enhanced 3D MRCP imaging was highly sensitive and specific in identifying variants of the intrahepatic bile ducts. This technique should be included in the standard protocol of preoperative radiologic evaluation of RL living donor candidates.

A simple new formula to assess liver weight

INTRODUCTION

In cadaveric or segmental liver transplantation, accurate assessment of graft volume is desirable but not always easy to achieve based on donor morphometric data. We sought to establish a simple, reliable formula for accurate prediction of liver volume.

METHODS

Data from 1,413 cadaveric adult and pediatric liver donors were analyzed using simple and multiple regression analysis. Liver weight (LW) was plotted against age, height, body weight (BW), body surface area (BSA) or body mass index (BMI); a formula was developed using simple regression: LW (g) = 772 (g/m(2)) x BSA, r = 0.73, P <.01. For donors with BSA </=1.0, a pediatric factor (PF) of 1.0 was included, resulting in the formula: LW (g) = 772 (g/m(2)) x BSA - 38PF, r = 0.73, P <.01. We then applied our formula on 5 published formulae to estimate LW of our donors.

RESULTS

Among donors with BSA >1.0, there was no significant difference between the actual and the estimated mean LW as calculated by the new formula. For pediatric donors, there was no significant difference between estimated and actual mean liver weight with any formula. When the new formula was applied, the difference between the actual and the estimated liver weight was acceptable (<20%) in 1040 (73.6%) cases. In all races, there was no significant difference between actual and estimated mean liver weight as calculated by this formula.

CONCLUSIONS

A simple formula to calculate liver weight in donors with BSA >1.0 is: LW = 772 x BSA, and for donors with BSA </=1.0: Liver Weight = 772 x BSA - 38.

Critical graft size in adult-to-adult living donor liver transplantation: impact of the recipient's disease

The aim of this study is to analyze the impact of the recipient's disease severity on graft size requirements and outcome in adult-to-adult living donor liver transplantation. A limiting factor in adult-to-adult living donor liver transplantation has been adequacy of graft size. A minimal graft-recipient weight ratio (GRWR) of 0.8% to 1% has been suggested, without taking the recipient's disease into account. Forty adults underwent liver transplantation using left (n = 10; mean weight, 481 +/- 83 g) or right lobes (n = 30; mean weight, 845 +/- 182 g). We recorded graft survival, Child-Turcotte-Pugh score, and occurrence of small-for-size syndrome (poor bile production, prolonged postoperative prothrombin time, and cholestasis without ischemia markers). Small grafts were defined as GRWR of < or =0.85%. Large grafts were defined as GRWR greater than 0.85%. Six patients died within 6 months of transplantation (early patient survival rate, 85%); two patients died late of tumor recurrence. Among transplant recipients with normal liver function or Child's class A, there was no significant difference with the use of small (n = 6) or large (n = 9) grafts (graft survival rates, 83% v 88%, respectively; P =.65). Among patients with Child's class B or C, graft survival rates were 74% in recipients of large grafts (n = 19) and 33% in recipients of small grafts (n = 6; P =.023). Five of 6 patients with Child's class B or C who received small grafts developed small-for-size syndrome; 2 patients died (1 patient after retransplantation) and 3 patients survived (2 patients after retransplantation). Graft function and survival are influenced not only by graft size, but also by pretransplantation disease severity. GRWR as low as 0.6% can be used safely in patients without cirrhosis or in patients with Child's class A. Transplant recipients with Child's class B or C require a GRWR greater than 0.85% to avoid small-for-size syndrome and related complications.

Orthotopic liver transplantation for Wilson's disease: a single-center experience

BACKGROUND

Wilson's disease is an inherited disorder of copper metabolism characterized by reduced biliary copper excretion, which results in copper accumulation in tissues with liver injury and failure. Orthotopic liver transplantation (OLT) can be lifesaving for patients with Wilson's disease who present with fulminant liver failure and for patients unresponsive to medical therapy. The aim of this study is to review our experience with OLT for patients with Wilson's disease.

METHODS

Between 1988 and 2000, 21 OLTs were performed in 17 patients with Wilson's disease. Patient demographics, pre-OLT laboratory data, operative data, and early and late postoperative complications were reviewed retrospectively. One-year patient and graft survival was calculated.

RESULTS

Eleven patients had fulminant Wilson's disease; in six patients the presentation was chronic. Mean patient age at presentation was 28 years (range 4-51 years); mean follow-up was 5.27 years (range 0.4-11.4 years). Neurologic features of Wilson's disease were not prominent preoperatively and did not develop post-OLT except in one patient who developed acute neuropsychiatric illness and seizure. Renal failure, present in 45% of patients with fulminant Wilson's disease, resolved post-OLT with supportive care. One-year patient and graft survivals were 87.5% and 62.5%, respectively. Fifteen survivors have remained well with normal liver function and no disease recurrence.

CONCLUSION

Liver transplantation for hepatic complications of Wilson's disease cures and corrects the underlying metabolic defect and leads to long-term survival in patients who present with either acute or chronic liver disease. Acute renal failure develops frequently in patients with fulminant Wilsonian hepatitis and typically resolves postoperatively.

Liver transplantation at Mount Sinai

Nearly 2000 liver transplants have been performed over the past 12 years at Mount Sinai, with a recent exponential growth in living donor surgeries. Living-donor liver transplantation has emerged as an important option for our patients with end-stage liver disease. We are only beginning to recognize fully the advantages that 'scheduled' liver transplantation can offer. In this era of severe cadaver organ shortages, living donation offers patients the option of liver replacement in a timely fashion, before life-threatening complications of hepatic failure and/or carcinoma progression prohibit transplantation. The next era of transplantation at Mount Sinai will bring significant increases in the number of transplants performed with living donors, with projections of over 50% of the total transplants each year expected to involve living donations. We are committed to offering this option while recognizing that donor safety remains paramount and cannot be overemphasized. Proper donor and recipient selection, as well as surgical experience are imperative to success with this technically demanding procedure. Recurrent disease after transplantation, particularly with hepatitis C, remains a challenge clinically. Further investigations into the pathogenesis of the rapid progression of recurrent hepatitis C need to be addressed. Living donor transplantation could be an important option for these patients and would allow timely transplantation and the potential for improved survival in patients with hepatocellular carcinoma.

One hundred nine living donor liver transplants in adults and children: a single-center experience

OBJECTIVE

To summarize the evolution of a living donor liver transplant program and the authors' experience with 109 cases.

SUMMARY BACKGROUND DATA

The authors' institution began to offer living donor liver transplants to children in 1993 and to adults in 1998.

METHODS

Donors were healthy, ages 18 to 60 years, related or unrelated, and ABO-compatible (except in one case). Donor evaluation was thorough. Liver biopsy was performed for abnormal lipid profiles or a history of significant alcohol use, a body mass index more than 28, or suspected steatosis. Imaging studies included angiography, computed tomography, endoscopic retrograde cholangiopancreatography, and magnetic resonance imaging. Recipient evaluation and management were the same as for cadaveric transplant.

RESULTS

After ABO screening, 136 potential donors were evaluated for 113 recipients; 23 donors withdrew for medical or personal reasons. Four donor surgeries were aborted; 109 transplants were performed. Fifty children (18 years or younger) received 47 left lateral segments and 3 left lobes; 59 adults received 50 right lobes and 9 left lobes. The average donor hospital stay was 6 days. Two donors each required one unit of banked blood. Right lobe donors had three bile leaks from the cut surface of the liver; all resolved. Another right lobe donor had prolonged hyperbilirubinemia. Three donors had small bowel obstructions; two required operation. All donors are alive and well. The most common indications for transplant were biliary atresia in children (56%) and hepatitis C in adults (40%); 35.6% of adults had hepatocellular carcinoma. Biliary reconstructions in all children and 44 adults were with a Roux-en-Y hepaticojejunostomy; 15 adults had duct-to-duct anastomoses. The incidence of major vascular complications was 12% in children and 11.8% in adult recipients. Children had three bile leaks (6%) and six (12%) biliary strictures. Adult patients had 14 (23.7%) bile leaks and 4 (6.8%) biliary strictures. Patient and graft survival rates were 87.6% and 81%, respectively, at 1 year and 75.1% and 69.6% at 5 years. In children, patient and graft survival rates were 89.9% and 85.8%, respectively, at 1 year and 80.9% and 78% at 5 years. In adults, patient and graft survival rates were 85.6% and 77%, respectively, at 1 year.

CONCLUSION

Living donor liver transplantation has become an important option for our patients and has dramatically changed our approach to patients with liver failure. The donor surgery is safe and can be done with minimal complications. We expect that living donor liver transplants will represent more than 50% of our transplants within 3 years.

Intratumoral adenovirus-mediated suicide gene transfer for hepatic metastases from colorectal adenocarcinoma: results of a phase I clinical trial

Animal studies have shown that direct injection of an adenoviral vector (Adv.RSV-tk) expressing the herpes thymidine kinase gene into established tumors in the liver, followed by systemic ganciclovir administration, was effective in inducing tumor necrosis. Toxicities were minimal at therapeutically effective vector doses, although severe hepatic necroinflammation was seen at much higher supratherapeutic doses. We conducted a clinical phase I trial in patients with metastatic colorectal adenocarcinoma in the liver to assess the safety of intratumoral Adv.RSV-tk injection (escalating doses) followed by intravenous ganciclovir (fixed dose). The vector was injected into a metastatic tumor in the liver under local anesthesia by percutaneous needle placement with concurrent ultrasonographic monitoring to prevent injection or leakage into adjacent normal liver structures. We treated 16 patients in five dose level cohorts of Adv.RSV-tk, from 1.0x10(10) to 1.0x10(13) virus particles per patient. Hepatic toxicities were low, with transient grade 1 elevations in serum aminotransferase levels in 3 of 16 patients. Other toxicities were also transient: grade 2-3 fevers in 5 of 16 patients, grade 3 thrombocytopenia in 1 of 16 patients, and grade 2 leucopenia in 3 of 16 patients. These results indicate that Adv.RSV-tk can be safely administered by percutaneous intratumoral injection in patients with hepatic metastases at doses up to 1.0x10(13) virus particles per patient, and can provide the basis for future clinical trials involving intratumoral adenoviral vector injection.

2'-Hydroxyl-protecting groups that are either photochemically labile or sensitive to fluoride ions

Protected ribonucleotide monomers are more difficult to obtain than their 2'-deoxy counterparts because of the need to protect the 2'-hydroxy function. This unit describes the stepwise preparation of suitably 2'-protected ribonucleosides using two protecting groups: 2-nitrobenzyloxymethyl (NBOM) and tert-butyldimethylsilyl (TBDMS). In addition, details are given for protecting the 5'-hydroxyl and the nucleobase, yielding nucleosides that are easily converted to phosphoramidite or H-phosphonate derivatives for automated oligoribonucleotide synthesis.

Use of daclizumab as initial immunosuppression in liver transplant recipients with impaired renal function

The addition of daclizumab (a human immunoglobulin G1 monoclonal antibody that blocks interleukin-2 receptors on T lymphocytes) to mycophenolate mofetil (MMF) and steroids is a new option for initial immunosuppression in patients undergoing liver transplantation (LT) with impaired renal function. We evaluated the efficacy and safety of daclizumab in preventing rejection in 25 patients with impaired kidney function undergoing LT. Patients with serum creatinine (Cr) levels greater than 2 mg/dL immediately before LT were administered initial immunosuppression with daclizumab, 1 mg/kg, in addition to MMF, 2 g/d, and methylprednisolone. Tacrolimus was added after kidney function improved (when Cr levels improved by >25% of initial value). Daclizumab-treated patients were compared retrospectively with 2 other groups of patients who underwent LT with kidney impairment (Cr > 2 mg/dL): 56 patients were administered OKT3 induction, and 48 patients were administered low-dose tacrolimus. The incidence of rejection and infection (bacterial, fungal, and viral), need for preoperative and postoperative dialysis, Cr level immediately post-LT and at 3 months, and graft and patient survival were analyzed. There was no difference among the groups in 3-month Cr levels or the incidence of rejection or fungal or viral infection. The daclizumab group had fewer bacterial infections (n = 13) than the tacrolimus group (n = 28) and significantly fewer than the OKT3 group (n = 58; P =.006). Only 1 patient (4%) in the daclizumab group required dialysis post-LT versus 13 patients in each of the other groups (OKT3, 23.21%; P <.05; tacrolimus, 27%). In the daclizumab group, 2-year patient and graft survival rates were statistically significant compared with the low-dose tacrolimus group (89% and 81% v 73% and 69%, respectively; P =.06). There were no side effects related to daclizumab use, and all patients tolerated the drug well. In patients with impaired renal function before LT, daclizumab-based initial immunosuppression can be used safely to reduce the risk for infection and need for dialysis post-LT, with improved long-term graft and patient survival.

A 67-year-old man with hepatitis C virus infection and a liver tumor

A 67-year-old man with no known liver disease was found to have an incidental tumor in the right liver lobe. His serum liver enzyme and alphafetoprotein were within normal limits, but he was found to be reactive for anti-HCV. The tumor was an intrahepatic cholangiocarcinoma. Since the only risk factor in this patient was hepatitis C infection, this case appears to support the recently suggested role of hepatitis C virus in the development of intrahepatic cholangiocarcinoma.

Recurrence of hepatitis C after liver transplantation is associated with increased systemic IL-10 levels

BACKGROUND

Recurrence of hepatitis C after liver transplantation is an almost universal occurrence. T-cell derived cytokines have an important role in the development of liver damage associated with chronic hepatitis C, their post-transplant levels, however, have not been correlated with histologic recurrence of the disease.

AIMS

We sought to analyze levels of TNF-alpha, soluble IL-2 receptor, IL-4 and IL-10 at 1 month, 6 months and 1 year after transplantation in 27 patients undergoing transplantation for hepatitis C related end-stage liver disease.

METHODS

HCV RNA levels were monitored by a branched-chain DNA signal amplification assay. Diagnosis of recurrent hepatitis was based on 1-year protocol biopsies and on biopsies performed for liver enzyme elevations.

RESULTS

Recurrent hepatitis C was detected in 52% (n=14) of the 27 patients. HCV RNA levels rose over time in all patients regardless of histologic recurrence. TNF-alpha, and IL-4 levels, although elevated, did not show specific patterns over time or in correlation with recurrence. Similarly, the early elevation followed by a gradual decrease over the first year in the amount of soluble IL-2 receptor was not related to histologic recurrence. We observed a significant increase in circulating IL-10 levels over the first year in patients with biopsy-proven recurrence, while patients with no signs of histologic recurrence displayed increased, but steady levels.

CONCLUSIONS

These results suggest that while these cytokines are associated with post-transplant recurrence of hepatitis C, their production may be altered by additional factors.

Safety and risk of using pediatric donor livers in adult liver transplantation

Pediatric donor (PD) livers have been allocated to adult transplant recipients in certain situations despite size discrepancies. We compared data on adults (age > or = 19 years) who underwent primary liver transplantation using livers from either PDs (age < 13 years; n = 70) or adult donors (ADs; age > or = 19 years; n = 1,051). We also investigated the risk factors and effect of prolonged cholestasis on survival in the PD group. In an attempt to determine the minimal graft volume requirement, we divided the PD group into 2 subgroups based on the ratio of donor liver weight (DLW) to estimated recipient liver weight (ERLW) at 2 different cutoff values: less than 0.4 (n = 5) versus 0.4 or greater (n = 56) and less than 0.5 (n = 21) versus 0.5 or greater (n = 40). The incidence of hepatic artery thrombosis (HAT) was significantly greater in the PD group (12.9%) compared with the AD group (3.8%; P =.0003). Multivariate analysis showed that preoperative prothrombin time of 16 seconds or greater (relative risk, 3.206; P =.0115) and absence of FK506 use as a primary immunosuppressant (relative risk, 4.477; P =.0078) were independent risk factors affecting 1-year graft survival in the PD group. In the PD group, transplant recipients who developed cholestasis (total bilirubin level > or = 5 mg/dL on postoperative day 7) had longer warm (WITs) and cold ischemic times (CITs). Transplant recipients with a DLW/ERLW less than 0.4 had a trend toward a greater incidence of HAT (40%; P <.06), septicemia (60%), and decreased 1- and 5-year graft survival rates (40% and 20%; P =.08 and.07 v DLW/ERLW of 0.4 or greater, respectively). In conclusion, the use of PD livers for adult recipients was associated with a greater risk for developing HAT. The outcome of small-for-size grafts is more likely to be adversely affected by longer WITs and CITs. The safe limit of graft volume appeared to be a DLW/ERLW of 0. 4 or greater.

Comparison of surgical outcomes for hepatocellular carcinoma in patients with hepatitis B versus hepatitis C: a western experience

BACKGROUND

We reviewed our experience in patients with hepatocellular carcinoma (HCC) and chronic hepatitis to determine if differences exist in preoperative status and postoperative survival between those with hepatitis B virus (HBV) and hepatitis C virus (HCV) infections.

METHODS

We reviewed the records of 240 consecutive patients with HCC who underwent hepatic resection or liver transplantation at Mount Sinai Hospital between February 1990 and February 1998. Patients who tested negative for hepatitis B antigen and hepatitis C antibody (74 patients) as well as those who tested positive for both (2 patients) were excluded. Age as well as preoperative platelet count, prothrombin time (PT), albumin, and total bilirubin were measured in all patients. The presence of encephalopathy or ascites also was noted. Explanted livers and resection specimens were examined for size, number, and differentiation of tumors as well as the presence of vascular invasion and cirrhosis in the surrounding parenchyma.

RESULTS

One hundred twenty-one patients with HCC tested positive for HCV, and 43 tested positive for HBV. A significantly higher proportion of patients with HCV required transplant for the treatment of their HCC when compared to those with HBV. In the resection group, patients with HCV were significantly older that those with HBV. They also had significantly lower mean preoperative platelet counts and albumin levels and higher mean PT and total bilirubin levels. Resected patients with HCV had significantly less-differentiated tumors and a higher incidence of vascular invasion and cirrhosis when compared to those with HBV. There was no statistical difference in the multicentricity and size of tumors between the two groups. The 5-year disease-free survival was significantly higher for HBV patients treated with resection when compared to those with HCV (49% vs. 7%, P = .0480). Patients with HCC and HCV had significantly longer 5-year disease-free survival with transplant when compared to resection (48% vs. 7%, P = .0001). Transplanted patients with HBV and HCC had preoperative status, pathological findings, and survival similar to those of patients with HCV.

CONCLUSIONS

Based on preoperative liver function and tumor location, a much higher proportion of HCC patients with HBV were candidates for resection. Significant differences in preoperative status, tumor characteristics and disease-free survival exist between HCC patients with chronic HBV and HCV infection who have not yet reached end-stage liver disease. Serious consideration should be given to transplanting resectable HCC with concomitant HCV, especially in cases with small tumors.