Analysis of the Factors That Affect the Detection Duration of SARS-CoV-2 in Loop Mediated Isothermal Amplification among COVID-19 Inpatients.

In COVID-19 patients who are immunocompromised or have severe COVID-19, the duration of infectious viral shedding may be longer, and a longer isolation duration is recommended. At the National Sagamihara Hospital, a decline in the viral load to end the isolation of hospitalized patients with COVID-19 was confirmed using loop-mediated isothermal amplification (LAMP). However, a subset of patients displayed LAMP positivity for more than 20 days after symptom onset. Therefore, we conducted a retrospective observational study to investigate the factors that affect the persistence of LAMP positivity. This study included a total of 102 participants. The severity of COVID-19 was mild (25.5%), moderate (67.6%), or severe (6.9%). The median number (interquartile range) of days until negative LAMP results from symptom onset were 16 (14-19) days. Multivariate logistic regression analysis showed that patients ≥55 years and/or those with the delta variant were correlated with persistent LAMP positivity for more than 20 days after symptom onset. This study identified age, the delta variant, and oxygen requirement as factors that contribute to persistently positive LAMP results. Therefore, it is posited that in these patients, the implementation of LAMP for deisolation would result in a prolonged isolation duration.

A de novo gain-of-function KCND3 mutation in early repolarization syndrome.

BACKGROUND: Early repolarization syndrome (ERS) is characterized by J-point elevation on electrocardiograms and ventricular fibrillation (VF). Early repolarization arises from augmentation of the transmural electrical gradient in the cardiac action potential; therefore, the transient outward potassium current (Ito) has been regarded as a key candidate current for elucidating the mechanism of ERS. KCND3 encoding Kv4.3, an α-subunit of the Ito channel, is considered as one of target genes. OBJECTIVE: The purpose of this study was to search for novel KCND3 mutations associated with ERS and to clarify the pathogenesis. METHODS: We performed genetic screening for 11 unrelated probands with ERS and analyzed the electrophysiological properties of detected mutations by patch-clamp methods. RESULTS: A novel de novo KCND3 heterozygous mutation, Gly306Ala (c.917g>c), was found in 1 proband. The proband was a 12-year-old boy, who suffered VF storm and showed significant J-point elevation in multiple leads. Intravenous isoproterenol and subsequent administration of quinidine were effective in preventing VF recurrence and restored the J-point elevation. In electrophysiological analysis, cultured cells expressing mutant Kv4.3 showed significantly increased current densities, slow inactivation, and slow recovery from inactivation compared to wild type. Extracellular application of quinidine significantly restored the inactivation time course in mutant Kv4.3. A simulation study confirmed the relationship between the novel KCND3 mutation and early repolarization on electrocardiograms. CONCLUSION: A novel KCND3 heterozygous mutation was found to be associated with ERS. The pathogenesis can be explained by the increased Ito. Genetic screening for KCND3 could be useful for understanding the pathogenesis and selecting effective treatment.

Novel intracellular transport-refractory mutations in KCNH2 identified in patients with symptomatic long QT syndrome.

BACKGROUND: Missense mutations in KCNH2, a gene encoding the Kv11.1 channel, cause long QT syndrome (LQTS) type 2 primarily by disrupting the intracellular transport of Kv11.1 to the plasma membrane. The present study aimed to clarify the functional changes by two novel KCNH2 missense mutations. METHODS: We performed genetic screening of three unrelated symptomatic LQTS probands with family histories of cardiac symptoms. Chinese hamster ovary cells were transfected with wild-type (WT) and/or mutant KCNH2 plasmid and examined by patch-clamp technique. Immunostaining and confocal microscopy were performed to evaluate the intracellular localization of WT and homozygous mutant Kv11.1 in human embryonic kidney cells. For the study of trafficking rescue, we used low-temperature incubation (30°C). We also examined pharmacological rescue of homozygous mutant Kv11.1 current in cells treated with E-4031 or dofetilide. RESULTS: We identified two novel KCNH2 missense mutations, G785D and T826I. Electrophysiological study showed that both mutant channels were nonfunctional in homozygous condition and reduced current densities by half in heterozygous condition compared with WT Kv11.1. Heterozygous Kv11.1-G785D produced a significant positive shift in activation and a significant negative shift in inactivation, whereas heterozygous Kv11.1-T826I caused no kinetic changes. Immunostaining revealed that both were transport-refractory mutations. Incubation at 30°C rescued plasma membrane expression of Kv11.1-T826I but not G785D. We confirmed low-temperature-induced restoration of homozygous Kv11.1-T826I transport by functional current measurements. In contrast, incubation with E-4031 or dofetilide failed to produce measurable currents in both homozygous mutant channels. CONCLUSIONS: Two novel KCNH2 mutations disrupted the intracellular transport of Kv11.1. Low-temperature incubation rescued plasma membrane expression of Kv11.1-T826I but not G785D. Both mutations exerted loss-of-function effects on Kv11.1 and explained the phenotypes of the mutation carriers.

Contribution of a KCNH2 variant in genotyped long QT syndrome: Romano-Ward syndrome under double mutations and acquired long QT syndrome under heterozygote.

BACKGROUND: Long QT syndrome (LQTS) presents two clinical phenotypes, congenital and acquired forms. This study aims to evaluate the genetic contribution of a KCNH2 variant for the two LQTS phenotypes. METHODS: From 1996 to 2014, genetic screening for LQTS probands was performed for five major genes: KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 and 389 probands were found to be mutation carriers. We analyzed the clinical phenotypes of p.His492Tyr carriers in KCNH2. RESULTS: Heterozygous p.His492Tyr variant was identified in 10 LQTS families. Six probands (mean age, 26±23 years) carried another mutation, and two of six had syncope associated with emotional stress or telephone ringing. The remaining four probands were significantly older at diagnosis (mean age, 42±33 years) and carried no other compound mutations. All the four probands had fatal arrhythmic events in the presence of additional precipitating factors such as culprit drugs in 2, hypokalemia in 1, and bradycardia in 1. The QTc interval of carriers with p.His492Tyr alone was 445±10ms and significantly shorter than that in double mutation carriers (481±40ms, p=0.041). CONCLUSIONS: KCNH2 p.His492Tyr variant presented Romano-Ward syndrome in the presence of another mutation and heterozygous carriers had mild phenotypes while even heterozygous carriers should be cared for not to encounter secondary factors because incidental factors could manifest "latent" form of p.His492Tyr heterozygous carriers.

Diltiazem-associated photodistributed hyperpigmentation: report of two Japanese cases and published work review.

Scherschum et al. proposed diltiazem-associated photodistributed hyperpigmentation as a novel type of drug-induced photosensitive lichenoid eruption. The characteristic clinical features were slate-gray reticulated hyperpigmentation on sun-exposed areas, while lichenoid dermatitis with prominent pigmentary incontinence was noted histologically. Although the clinical and histological features were similar to those of lichen planus pigmentosus, the histological features did not show either compact hyperkeratosis or wedge-shaped hypergranulosis, which are typical histological features of lichen planus. We describe two Japanese cases of diltiazem-associated photodistributed hyperpigmentation, who were successfully treated with topical tacrolimus, and review the published work.

Centrifugal lipodystrophy of the scalp presenting with an arch-form alopecia: a 10-year follow-up observation.

We describe a 10-year follow-up observation of progressive arch-form alopecia caused by centrifugal lipodystrophy (CLD) in a Japanese boy. A 2.5-year-old boy developed a slightly depressed lesion demarcated by a horseshoe-shaped erythematous border on his right neck, which then extended to the scalp. Four years later, arch-form alopecia became apparent in the right temporal region along with an erythematous border. The arch-form alopecia gradually expanded centrifugally, leaving a slight residual depression, but hair regrowth was seen within the area of alopecia. Histological examination of the erythematous border revealed non-specific inflammatory changes in the subcutaneous fat. Magnetic resonance imaging findings revealed a loss of subcutaneous fat inside the lesion. The alopecia continuously extended until he was 12 years old, but, thereafter, expansion ceased and hair regrowth gradually occurred in the arch-form alopecia. A linear non-hairy lesion 5 cm in length still remained when he was 13 years old. CLD might involve the scalp and cause linear, arch-form alopecia.

Verrucous carcinoma of the scalp associated with human papillomavirus type 33.

BACKGROUND: Verrucous carcinoma (VC) is a low-grade, well-differentiated squamous cell carcinoma of the skin or mucosae, and human papillomavirus (HPV) infection has been considered to be one of the causative factors of VC at three main sites, including the oral cavity, the genitoanal region, and the foot. However, the relationship between cutaneous VC at other sites and HPV infection remains obscure. OBJECTIVE: We describe a rare case of cutaneous VC originating in a burn scar on the scalp and our attempt to find HPV infection in the lesion. METHODS: We investigated the presence of HPV by polymerase chain reaction-restriction fragment length polymorphisms and immunohistochemical analysis. RESULTS: HPV type 33 was detected in the lesion, and positive stains for HPV were observed in several cell nuclei at the upper stratum malpighi. CONCLUSION: Since HPV type 33, as well as HPV types 16 and 18, is regarded as a high-risk, mucosal type, HPV type 33 infection likely contributed to the development of the lesion. We suggest that HPV infection should be relevant to a subset of cutaneous VC.