Association of poor oral health status and faecal incontinence in patients with dysphagia: A cross-sectional analysis from the Sarcopenic Dysphagia Database

BACKGROUND

Poor oral health status may alter oral and gut microbiota. Previous studies have shown that poor oral health can exacerbate gut inflammation. Therefore, poor oral health status may be related to faecal incontinence via changes in the gut.

OBJECTIVE

To investigate the association between poor oral health status and faecal incontinence in inpatients with dysphagia.

METHODS

This multicentre cross-sectional study included 423 patients (mean age 79.8 ± 11.5 years, 48.2% female) with dysphagia. Oral health status was assessed at each facility using the Oral Health Assessment Tool (OHAT) or the Revised Oral Assessment Guide (ROAG). Poor oral health status was defined as an OHAT score of ≥3 or a ROAG score of ≥13. A multivariate logistic model was used to analyse the association between poor oral health status and faecal incontinence.

RESULTS

A total of 351 (83.0%) patients had poor oral health and 97 (22.7%) had faecal incontinence. Patients with poor oral health status had a higher proportion of faecal incontinence than those with normal oral health status (25.4% vs. 11.1%, p = .009). A multivariate logistic model revealed an association between faecal incontinence and poor oral health status (adjusted odds ratio = 2.501, 95% confidence interval = 1.065-5.873, p = .035).

CONCLUSIONS

Poor oral health status assessed by OHAT or ROAG in inpatients with dysphagia may adversely affect faecal incontinence. Further studies are needed to determine the causal relationship between poor oral health status and faecal incontinence.

A Case of Dysphagia and Dysarthria Improved by Flexible-palatal Lift/augmentation Combination Prosthesis

Background

Palatal augmentation prosthesis (PAP) and palatal lift prosthesis (PLP) have been used to improve dysphagia and dysarthria. However, to date, there are few reports on their combined use. We report a quantitative evaluation of the effectiveness of a flexible-palatal lift/augmentation combination prosthesis (fPL/ACP) based on videofluoroscopic swallowing study (VFSS) and speech intelligibility testing.

Case

An 83-year-old woman was admitted to our hospital with a hip fracture. She developed aspiration pneumonia at 1 month after partial hip replacement. Oral motor function tests revealed a motor deficit of the tongue and soft palate. VFSS showed delayed oral transit, nasopharyngeal reflux, and excessive pharyngeal residue. The cause of her dysphagia was assumed to be pre-existing diffuse large B-cell lymphoma and sarcopenia. To improve the dysphagia, an fPL/ACP was fabricated and applied. It improved the patient's oral and pharyngeal swallowing and speech intelligibility. In addition to prosthetic treatment, rehabilitation and nutritional support allowed her to be discharged.

Discussion

The effects of fPL/ACP in the present case were similar to those of flexible-PLP and PAP. f-PLP assists in elevation of the soft palate and improved the nasopharyngeal reflux and hypernasal speech. PAP promotes tongue movement and results in improved oral transit and speech intelligibility. Therefore, fPL/ACP may be effective in patients with motor deficits in both the tongue and soft palate. To maximize the effect of the intraoral prosthesis, a transdisciplinary approach with concurrent swallowing rehabilitation, nutritional support, and physical and occupational therapy is necessary.

Association of medial gastrocnemius adiposity with poststroke severe malnutrition and functional performance of activities of daily living in older patients: A prospective analysis

BACKGROUND

Relationships among medial gastrocnemius intramuscular adipose tissue, nutrition status, and functional outcomes of patients after a stroke are unknown. This study was conducted to determine the relationship between nutrition status and gastrocnemius intramuscular adipose tissue and whether medial gastrocnemius intramuscular adipose tissue affects functional outcomes of older patients after a stroke.

METHODS

This prospective cohort study included 217 patients with stroke. Nutrition status was evaluated by the Global Leadership Initiative on Malnutrition. The medial gastrocnemius intramuscular adipose tissue was assessed using ultrasound echographic intensity. Multivariate linear regression analysis was used to determine the relationship between nutrition status at admission and medial gastrocnemius intramuscular adipose tissue. Furthermore, we examined the influence of medial gastrocnemius intramuscular adipose tissue on the Functional Independence Measure (FIM)-motor score at discharge and FIM-motor efficiency, which indicates FIM-motor changes during the hospital stay.

RESULTS

Severe malnutrition had a positive influence on medial gastrocnemius intramuscular adipose tissue on the nonparalyzed side (β = 0.175; P = 0.044). Additionally, the medial gastrocnemius intramuscular adipose tissue on the nonparalyzed side was negatively correlated with the FIM-motor score at discharge (β = -0.102; P = 0.005) and FIM-motor efficiency (β = -0.273; P = 0.005).

CONCLUSIONS

This study clarified the factors that contribute to a higher medial gastrocnemius intramuscular adipose tissue content on the nonparalyzed side and the effect of the higher adipose tissue content on functional outcomes.

Research Note: Expression of IGF-1 and IGF-1 Receptor Proteins in Skeletal Muscle Fiber Types in Chickens with Hepatic Fibrosis

We investigated the expression of insulin-like growth factor 1 (IGF-1) and IGF-1 type 1 receptor (IGF-1R) in skeletal muscle fiber types in chickens with hepatic fibrosis induced by bile duct ligation (BDL). Eleven hens, approximately 104 weeks old, were randomly assigned to BDL (n = 4) and sham surgery (SHAM; n = 7) groups. In BDL hens, histopathology revealed marked bile duct proliferation and liver fibrosis. The cross-sectional area (CSA) of myofibers from both the pectoralis (PCT) muscles significantly decreased in the BDL group compared with the SHAM group (P < 0.01). In contrast, the CSA of myofibers from the femorotibialis lateralis (FTL) muscle did not decrease in the BDL group. Type I fibers were large, round, and hypertrophic. Elongated type IIA and IIB fibers were also present. For IGF-1 immunostaining, the immunoreaction intensity was higher in the PCT in the BDL group than the SHAM group. Within the BDL group, type I fibers from FTL had a stronger immunoreaction intensity than the type II fibers. For IGF-1R immunostaining, the intensity of the immunoreactions was similar within the PCT in the BDL group compared with the SHAM group. For FTL, type I fibers had stronger reactions to IGF-1R than type II fibers in the BDL group. These results suggest that type I fibers express both IGF-1 and IGF-1R and become hypertrophic in chickens with hepatic fibrosis.

Compensatory swallowing methods in a patient with dysphagia due to lateral medullary syndrome-vacuum and prolonged swallowing: A case report

INTRODUCTION

The nature of pharyngeal swallowing function during the course of recovery of dysphagia due to lateral medullary syndrome (LMS) is unclear. Vacuum swallowing is a compensatory swallowing method that improves the pharyngeal passage of a bolus by creating negative pressure during swallowing in the esophagus in patients with dysphagia due to LMS. We present a case involving a patient with dysphagia due to LMS who involuntarily acquired a swallowing method with prolonged and increased pharyngeal contraction and vacuum swallowing.

PATIENT CONCERNS

We report a unique case involving a 52-year-old patient with dysphagia due to LMS. His dysphagia was severe but improved gradually with swallowing rehabilitation. The patient involuntarily acquired a swallowing method with prolonged and increased pharyngeal contraction and vacuum swallowing.

DIAGNOSIS

The patient presented with dysphagia due to left LMS. A videofluoroscopic examination of swallowing revealed pharyngeal residue.

INTERVENTIONS

Forty-five days after the onset of the dysphagia, the swallowing pressure along the pharynx and esophagus was measured using high-resolution manometry.

OUTCOMES

Vacuum swallowing was observed in six out of 19 swallows (32.5%). The velopharyngeal contractile integral (CI) and mesohypopharyngeal CI values increased during swallowing, reflecting prolonged and increased pharyngeal contraction. We named this swallowing method "prolonged swallowing."

CONCLUSION

The findings in this case indicate that vacuum and prolonged swallowing may be compensatory swallowing methods observed in individuals recovering from dysphagia due to LMS. Further research is needed to clarify the relationship between these swallowing methods and the pathophysiology, prognosis, and treatment of dysphagia in patients with LMS.

Poor oral health and anorexia in older rehabilitation patients

OBJECTIVE

To investigate the association between anorexia and comprehensive oral health status in older inpatients.

BACKGROUND

Anorexia in older inpatients is a major concern, but whether it is associated with oral problems is currently unclear.

METHODS

This cross-sectional study included 160 participants (42.5% men) aged ≥65 years (mean age 78.6 ± 7.9) who had been admitted to a rehabilitation hospital. A score of ≤14 on the Simplified Nutritional Appetite Questionnaire for Japanese Elderly indicated anorexia. A score of ≥3 on the Oral Health Assessment Tool (OHAT) indicated poor oral health. Malnutrition was diagnosed according to the criteria set out by the Global Leadership Initiative on Malnutrition. Multivariate logistic regression was used to investigate the association between poor oral health and anorexia and, additionally, which subcategory of the OHAT (represented by a score ≥1) was associated with anorexia.

RESULTS

Anorexia and poor oral health status were observed in 86 (53.8%) and 85 (53.1%), respectively. Poor oral health was associated with anorexia after adjusting for potential confounders (adjusted odds ratio [AOR] 2.7; 95% confidence interval [CI]: 1.3-5.9). Additionally, poor status of dentures (AOR 2.6; 95% CI: 1.2-5.7) and poor oral cleanliness (AOR 3.0; 95% CI: 1.4-6.4) were independently associated with anorexia.

CONCLUSIONS

Poor oral health was associated with anorexia in older inpatients. Detection of poor oral health status using a comprehensive oral health assessment may be useful for anorexic patients. Early detection for poor oral health using comprehensive oral health assessments and oral care and prosthetic treatment may be useful for anorexic patients.

Delayed Dysphagia May Be Sarcopenic Dysphagia in Patients After Stroke

OBJECTIVE

In many cases, swallowing function is impaired after the onset of stroke and gradually improves. However, delayed dysphagia has been reported in some post-stroke patients. Recently, several studies have reported that low muscle strength and decreased muscle mass cause dysphagia. This study aimed to investigate whether these conditions are associated with delayed dysphagia after stroke.

DESIGN

A multicenter prospective observational cohort study.

SETTING AND PARTICIPANTS

Participants included 165 patients with post-stroke dysphagia (mean age 79.1 ± 8.0 years, 53.3% women) admitted to rehabilitation wards for post-stroke rehabilitation.

METHODS

Swallowing function was assessed using the Functional Oral Intake Scale. Delayed dysphagia was defined as dysphagia that occurred more than 7 days after stroke onset. We used logistic regression to examine the independent association between low muscle strength and decreased muscle mass and delayed dysphagia development. Furthermore, we examined the relationship between improvement in dysphagia and delayed dysphagia.

RESULTS

Delayed dysphagia was observed in 18 (10.9%) patients. The combination of severely low muscle strength and decreased muscle mass was independently associated with the development of delayed dysphagia (adjusted odds ratio: 4.423, 95% confidence interval: 1.400-13.974, P = .011). Delayed dysphagia had an adverse effect on the improvement of dysphagia during in-hospital rehabilitation (adjusted odds ratio: 0.278, 95% confidence interval: 0.078-0.986, P = .047).

CONCLUSIONS AND IMPLICATIONS

The development of delayed dysphagia was influenced by a combination of severely low muscle strength and decreased muscle mass. Furthermore, delayed dysphagia adversely affects the improvement of dysphagia in patients with stroke and needs to be identified early. Identifying delayed dysphagia using the methods proposed in this study and incorporating early intervention may prevent or delay dependency conditions in this population.

Effect of dentures on pharyngeal swallowing function in patients with dysphagia

AIM

Dentures play an important role in improving masticatory and oropharyngeal swallowing functions in some edentulous patients without dysphagia. However, few studies have been conducted on patients with dysphagia. This study investigated the effect of dentures on pharyngeal swallowing function in patients with dysphagia.

METHODS

Older inpatients with dysphagia who used well-fitting dentures were included in the study. Videofluoroscopic swallowing study findings with and without dentures were compared. Pharyngeal residue and area as spatial, the distance between the maxilla and mandible, hyoid bone/laryngeal displacement, and upper esophageal sphincter opening as kinematics, oral/pharyngeal transit time as temporal measurements, and patient-reported symptoms were evaluated. The primary outcome was the pharyngeal residue measured using the normalized residue ratio scale. Comparisons were made using the paired t-test, Wilcoxon signed-rank test and Fisher's exact test.

RESULTS

The mean age of the 27 participants was 86.1 ± 6.8 years. The vallecular residue was more in those without dentures (with dentures: 0.01 [0-0.02], without dentures: 0.03 [0-0.08]; P = 0.003). The pyriform sinus residue showed no significant difference. Denture removal significantly increased the pharyngeal area. The distance between the maxilla and mandible decreased in the absence of dentures, and other kinematic measurements showed no significant differences. Oral/pharyngeal transit time was prolonged without dentures.

CONCLUSIONS

Morphological changes caused by the removal of dentures led to pharyngeal expansion, which may result in increased vallecular residue. A treatment plan that considers the effect of dentures on pharyngeal swallowing function may provide rehabilitation that is more effective. Geriatr Gerontol Int 2021; 21: 907-912.

Texture-Modified Diets are Associated with Poor Appetite in Older Adults who are Admitted to a Post-Acute Rehabilitation Hospital

OBJECTIVE

This study aimed to clarify the association between texture-modified diets and poor appetite in older adults, as it is not fully understood.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

We included 208 inpatients who were aged ≥65 years (mean age 78.9 ± 7.6 years, 57.7% female) and admitted to a rehabilitation unit with stroke, musculoskeletal disease, or hospital-associated deconditioning covered by the Japanese insurance system, between January 2019 and January 2020.

METHODS

Participants were divided into 2 groups according to their food texture level: International Dysphagia Diet Standardization Initiative (IDDSI) levels 3 to 5 for the texture-modified diet group and levels 6 and 7 for the normal diet group. Appetite was assessed using the Simplified Nutritional Appetite Questionnaire for the Japanese elderly, and a score ≤14 was defined as poor appetite. The relationship between IDDSI levels and poor appetite was analyzed using the Cochrane-Armitage trend test. Logistic regression analysis was used to investigate the relationship between the consumption of texture-modified diets and poor appetite. Statistical significance was set at P < .05.

RESULTS

The numbers of participants on modified diets according to the IDDSI framework were as follows: 4, 11, 41, 76, and 76 in levels 3, 4, 5, 6, and 7, respectively. In total, 152 and 56 patients were classified into the regular diet group and texture-modified diet group, respectively. A significantly higher prevalence of poor appetite was observed with the consumption of texture-modified diets (P < .001 for trend). Logistic regression analysis showed that poor appetite was independently associated with the consumption of texture-modified diets (odds ratio 3.443, P = .011).

CONCLUSIONS AND IMPLICATIONS

These findings indicate that the consumption of texture-modified diets is associated with poor appetite. Further studies are required to verify whether a multimodal approach involving improvement in the appearance, taste, flavor, and nutrients of the food can improve poor appetite.

Effect of low tongue pressure on nutritional status and improvement of swallowing function in sarcopenic dysphagia

OBJECTIVES

This study aimed to evaluate the effect of low tongue pressure on the improvement of swallowing function in people with sarcopenic dysphagia and ongoing dysphagia or physical rehabilitation. In addition, we investigated whether sarcopenic dysphagia at admission was associated with severity of malnutrition.

METHODS

This was a prospective cohort study of 146 people with sarcopenic dysphagia (mean age 84.6 ± 7.4 y; 68.4% women, 31.6% men) in a postacute rehabilitation hospital. Sarcopenic dysphagia was defined as the presence of both sarcopenia and dysphagia but not neurogenic dysphagia, such as dysphagia due to stroke. Low tongue pressure was classified as "probable" and normal tongue pressure as "possible" sarcopenic dysphagia. Swallowing function was assessed using the Food Intake Level Scale. Malnutrition was diagnosed using the Global Leadership Initiative on Malnutrition criteria. Study outcomes included the amount of change in Food Intake Level Scale score during the rehabilitation period and the association between probable sarcopenic dysphagia and the severity of malnutrition on admission. Statistical significance was set at P < 0.05.

RESULTS

There were 83 participants (58.6%) with probable sarcopenic dysphagia. The severity of malnutrition (moderate malnutrition: adjusted odds ratio, 3.388; P = 0.042) and severe malnutrition (adjusted odds ratio, 3.663; P = 0.015) was a contributing factor to probable sarcopenic dysphagia. Probable sarcopenic dysphagia (regression coefficient, -0.384; P = 0.017) was negatively associated with the amount of change in Food Intake Level Scale score.

CONCLUSIONS

Probable sarcopenic dysphagia with low tongue pressure was associated with poorer improvement in swallowing function and severe malnutrition during postacute rehabilitation. Patients with probable sarcopenic dysphagia may require aggressive nutritional therapy.

Incoordination during the pharyngeal phase in severe dysphagia due to lateral medullary syndrome

One of the mechanisms of severe dysphagia due to lateral medullary syndrome may be a reversed pressure gradient caused by incoordination of pharyngeal contractility and UES opening during swallowing.

Evaluation of a palatal lift prosthesis with a flexible lift in a lower cranial nerve palsy patient with dysphagia using high-resolution manometry: A case report

PATIENT

Palatal lift prostheses (PLPs) are used for dysarthria caused by velopharyngeal incompetence (VPI) and improving hypernasal speech. In this case, we used a PLP with a flexible lift (f-PLP) in a patient with dysphagia associated with VPI due to right-sided cranial nerve injuries after a skull base surgery. We examined its efficacy in swallowing biomechanics and swallowing function using high-resolution manometry (HRM) and videofluoroscopic examination of swallowing (VF). The patient felt that it was easier to swallow with f-PLP. Furthermore, VF indicated that the pharyngeal residue with f-PLP was less than without it. HRM showed that velopharyngeal pressure and intrabolus pressure (IBP) with f-PLP were higher than those without it. Additionally, the upper esophageal sphincter (UES) relaxation time and UES nadir pressure on the patient's healthy left side compared to the right side improved with f-PLP.

DISCUSSION

We discovered two clinical outcomes. First, the f-PLP ensured velopharyngeal closure and an increase in the hypopharyngeal IBP, which potentially improved the UES opening on the healthy side. Second, the f-PLP improved pharyngeal clearance, and the patient felt that it was easier to swallow with the f-PLP. This implies that an f-PLP potentially exhibits a positive effect on swallowing.

CONCLUSIONS

In this case, the f-PLP contributed to improving the pharyngeal passage of a bolus. We suggest that f-PLPs can be used for patients with dysarthria and those with dysphagia with VPI.

Nutritional Management Enhances the Recovery of Swallowing Ability in Older Patients with Sarcopenic Dysphagia

This study assessed whether a high provided energy of ≥30 kcal/ideal body weight (IBW)/day (kg) for patients with sarcopenic dysphagia effectively improved swallowing ability and the activities of daily living (ADLs). Among 110 patients with sarcopenic dysphagia (mean age, 84.9 ± 7.4 years) who were admitted to a post-acute hospital, swallowing ability and the ADLs were assessed using the Food Intake LEVEL Scale (FILS) and the Functional Independence Measure (FIM), respectively. The primary outcome was the FILS at discharge, while the secondary outcome was the achievement of the FIM with a minimal clinically important difference (MCID) at discharge. We created a homogeneous probability model without statistically significant differences using the inverse probability of treatment weighting (IPTW) method with and without a mean provided energy of ≥30 kcal/IBW/day (kg) for a period of 1 week of hospitalization and compared the outcomes between groups. A mean provided energy of ≥30 kcal/IBW/day (kg) was achieved in 62.7% of patients. In the IPTW model, the FILS and the rates of achieved MCID of the FIM at discharge were significantly higher in the mean provided energy of ≥30 kcal/IBW/day (kg) group (p = 0.004 and p < 0.001, respectively). A high provided energy for patients with sarcopenic dysphagia may improve swallowing ability and produce clinically meaningful functional outcomes.

Sarcopenic Dysphagia with Low Tongue Pressure Is Associated with Worsening of Swallowing, Nutritional Status, and Activities of Daily Living

OBJECTIVES

According to the recently proposed diagnostic criteria for sarcopenic dysphagia, sarcopenic dysphagia can be classified as probable or possible based on tongue pressure. However, it is unclear whether patients with probable and possible sarcopenic dysphagia have different characteristics. Therefore, this study aimed to investigate whether patients with possible and probable sarcopenic dysphagia have different clinical characteristics.

DESIGN

A cross-sectional study.

SETTING

A rehabilitation hospital.

PARTICIPANTS

In total, 129 patients aged ≥65 years with sarcopenic dysphagia were included.

METHODS

A tongue pressure of <20 kPa was indicative of probable sarcopenic dysphagia, and a tongue pressure of ≥20 kPa was indicative of possible sarcopenic dysphagia. Kuchi-Kara Taberu (KT) index scores were compared between the probable or possible sarcopenic dysphagia groups.

RESULTS

According to the tongue pressure, 76 and 53 patients were classified into the probable and possible sarcopenic dysphagia groups, respectively. In multiple linear regression analysis, the presence of probable sarcopenic dysphagia was independently associated with the total KT index score (standardized coefficient: -0.313, regression coefficient: -4.500, 95% confidence interval [CI], -6.920 to -2.080, P < 0.001). The presence of probable sarcopenic dysphagia was independently associated with some subitems of the KT index (willingness to eat, cognitive function while eating, oral preparatory and propulsive phase, severity of pharyngeal dysphagia, eating behavior, and daily living activities).

CONCLUSIONS

Patients with probable sarcopenic dysphagia were characterized by poor overall eating-related conditions, especially poor swallowing ability, ability to perform activities of daily living, and nutritional status.

Digastric muscle mass and intensity in older patients with sarcopenic dysphagia by ultrasonography

AIM

The aim of this study was to investigate digastric muscle mass and intensity between no sarcopenic dysphagia and sarcopenic dysphagia.

METHODS

Patients aged ≥65 years were enrolled. According to the diagnostic algorithm for sarcopenic dysphagia, the patients were divided into two groups, no sarcopenic dysphagia and sarcopenic dysphagia. Handgrip strength, gait speed, skeletal muscle mass, tongue pressure, Mini Nutritional Assessment-Short Form and Food Intake LEVEL Scale were investigated. Digastric muscle mass and intensity were examined by ultrasonography. Univariate and multivariate analyses were performed to analyze two groups. Multivariate logistic regression analysis was performed to determine independent factors for the presence of sarcopenic dysphagia. To estimate the accuracy of diagnosing sarcopenic dysphagia, a receiver operating characteristic curve analysis was performed for digastric muscle mass and intensity.

RESULTS

Forty-five patients (mean ± SD, 84.3 ± 7.8 years, 22 men, 23 women) including 19 no sarcopenic dysphagia and 26 sarcopenic dysphagia were examined. In sarcopenic dysphagia, lower BMI, Food Intake LEVEL Scale, Mini Nutritional Assessment-Short Form and smaller muscle mass and greater muscle intensity were found compared with no sarcopenic dysphagia. In multivariate logistic regression analysis, digastric muscle mass and intensity were identified as independent factors for sarcopenic dysphagia. The cut-off value of muscle mass was 75.1 mm² (area under curve: 0.731, sensitivity: 0.692, specificity: 0.737) and muscle intensity was 27.8 (area under curve: 0.823, sensitivity: 0.923, specificity: 0.632).

CONCLUSIONS

Digastric muscle mass was smaller and muscle intensity was greater in sarcopenic dysphagia than no sarcopenic dysphagia. Ultrasonography of digastric muscle, as well as the tongue and geniohyoid muscle, is useful. Geriatr Gerontol Int 2021; 21: 14-19.

Comparative aspects on the role of polypyrimidine tract-binding protein in internal initiation of hepatitis C virus and picornavirus RNAs

We compared the effects of polypyrimidine tract-binding protein (PTB) on hepatitis C virus (HCV genotype IIa), encephalomyocarditis virus (EMCV) and poliovirus internal ribosome entry site (IRES) activities in vitro. It bound strongly to EMCV IRES, but weakly to PV and HCV RNAs. PV IRES showed the strongest dependency to PTB and it showed less than one-tenth of IRES activity after the immuno-depletion of PTB from HeLa S10 lysate with pre-coated anti-PTB IgG beads, comparing to the normal IgG beads-treated S10 lysate. EMCV IRES activity was approximately 40% of that of normal control after PTB depletion. Especially, HCV IRES activity was approximately 95%, and most weekly affected by the depletion of PTB. Repletion of PTB to depleted S10 lysate restored activities of PV and EMCV IRESs. The data suggest that PTB plays an important role in picornaviral IRESs, but not in HCV IRES.

Host range of poliovirus is restricted to simians because of a rapid sequence change of the poliovirus receptor gene during evolution

The host range of most poliovirus (PV) strains is restricted to simians. This host range specificity is believed to be determined by the interaction between PV and its receptor molecule. To elucidate the molecular basis of this species-specific infection of PV, we cloned orthologs of the PV receptor (PVR) gene ( pvr) as well as those of PV receptor-related genes 1 and 2 ( prr1 and prr2) from various mammalian species. These three genes are widely present in mammalian genomes including those of non-susceptible species. Comparison of the deduced amino acid sequences of PVR orthologs revealed that the NH(2)-terminal immunoglobulin-like domain (domain 1), which is the virus binding site in the human PVR, is highly variable among species, whereas that of PRR1 is highly conserved. Domain 1 of the PVR orthologs for the ring-tailed lemur and rabbit, which are not susceptible to PV, show only 51 and 61% amino acid sequence identity to that of human PVR, respectively. Chimeric PVR proteins that have the domain 1 of the ring-tailed lemur and rabbit PVRs failed to serve as receptors for PV. These results suggest that rapid changes in the domain 1 sequence during mammalian evolution determined the host range restriction of PV.

The molecular basis of poliovirus neurovirulence

Species specificity of poliovirus (PV) is mostly governed by host cellular molecules that serve as the PV receptor (PVR). Molecular cloning of the gene and cDNAs of human PVR and the subsequent development of PV-sensitive transgenic (Tg) mice carrying the human PVR gene made it possible to investigate molecular mechanisms for PV-specific dissemination in the whole body. After intravenous inoculation which makes artificial viremia, poliovirus appears to enter the central nervous system (CNS) at a fairly high rate via the blood brain barrier, suggesting existence of a specific permeation system for PV. This main dissemination process does not require PVR. After intramuscular inoculation, PV appears to be incorporated by endocytosis at synapses, and the endosomes containing PV transported through axons to neuron cell body, where viral replication occurs. Efficiency of viral multiplication in the CNS probably determines the neurovirulence level, which differs between PV strains. An important determinant for neurovirulence phenotype resides in the internal ribosomal entry site (IRES). This has led us to a concept of "IRES-dependent virus tropism".

Molecular genetic analysis of revertants from a poliovirus mutant that is specifically adapted to the mouse spinal cord

SA virus, a mutant of the Mahoney strain of type 1 poliovirus (PV1/Mahoney), replicates specifically in the spinal cords of mice and causes paralysis, although the PV1/Mahoney strain does not show any mouse neurovirulence (Q. Jia, S. Ohka, K. Iwasaki, K. Tohyama, and A. Nomoto, J. Virol. 73:6041-6047, 1999). The key mutation site for the mouse neurovirulence of SA was mapped to nucleotide (nt) 928 of the genome (A to G), resulting in the amino acid substitution of Met for Ile at residue 62 within the capsid protein VP4 (VP4062). A small-plaque phenotype of SA appears to be indicative of its mouse-neurovirulent phenotype. To identify additional amino acid residues involved in the host range determination of PV, a total of 14 large-plaque (LP) variants were isolated from a single point mutant, Mah/I4062M, that showed the SA phenotype. All the LP variants no longer showed any mouse neurovirulence when delivered via an intraspinal inoculation route. Of these, 11 isolates had a back mutation at nt 928 (G to A) that restored the nucleotide of the PV1/Mahoney type. The reversions of the remaining three isolates (LP8, LP9, and LP14) were mediated by a second site mutation. Molecular genetic analysis involving recombinants between Mah/I4062M and the LP variants revealed that the mere substitution of an amino acid residue at position 107 in VP1 (Val to Leu) (LP9), position 33 in VP2 (Val to Ile) (LP14), or position 231 in VP3 (Ile to Thr) (LP8) was sufficient to restore the PV1/Mahoney phenotype. These amino acid residues are located either on the surface or inside of the virus particle. Our results indicate that the mouse neurovirulence of PV is determined by the virion surface structure, which is formed by all four capsid proteins.

Basolateral sorting of human poliovirus receptor alpha involves an interaction with the mu1B subunit of the clathrin adaptor complex in polarized epithelial cells

Poliovirus receptor (hPVR/CD155) is a cell surface glycoprotein that belongs to the immunoglobulin superfamily but its natural function remains unknown. Two membrane-bound isoforms, hPVRalpha and hPVRdelta, are known to date, and they differ only in the amino acid sequence of their cytoplasmic domains. To gain an insight into the possible function of the cytoplasmic domains, we examined the localization of introduced hPVRalpha and hPVRdelta in polarized epithelial cells deficient of native hPVRs. Basolateral sorting of hPVRalpha was observed in Madine-Darby canine kidney cells expressing mu1B, but not in LLC-PK1 porcine kidney cells deficient in mu1B. Distribution of hPVRdelta, however, occurred both on the apical and basolateral plasma membranes of these two cell lines. Basolateral sorting of hPVRalpha was also seen in LLC-PK1 cells that expressed an intact exogenous mu1B, but not in the cells that expressed a mutant mu1B lacking binding ability to tyrosine-containing signals. These results indicate that mu1B is involved in the distribution of hPVRalpha to the basolateral membrane. Comparative distribution analysis of hPVRalpha using a series of mutants with truncations and substitutions in the cytoplasmic tail demonstrated that determinant for the basolateral sorting resided in the tyrosine-containing motif of the cytoplasmic tail. Furthermore, yeast two hybrid analysis strongly suggested that the tyrosine motif directly interacted with mu1B protein. Thus, basolateral sorting of hPVRalpha appears to involve the interaction with mu1B through a tyrosine motif existing in the cytoplasmic domain.

Recent insights into poliovirus pathogenesis

The development of a mouse model for poliomyelitis that is transgenic for the human poliovirus receptor (hPVR) has made it much easier to investigate the efficiency of the viral dissemination process in a whole organism. These studies have given an insight into the mechanisms of blood-brain barrier permeation and neural transport. Strain-specific neurovirulence levels, however, appear to depend mainly on the replicating capacity of the virus in the central nervous system rather than the dissemination efficiency. Studies of the poliovirus-induced cytopathic effects on neural cells and specific subcellular localization of hPVR isoforms might determine a new course of investigation of poliovirus pathogenesis.

Regulation of the yeast Yap1p nuclear export signal is mediated by redox signal-induced reversible disulfide bond formation

Yap1p, a crucial transcription factor in the oxidative stress response of Saccharomyces cerevisiae, is transported in and out of the nucleus under nonstress conditions. The nuclear export step is specifically inhibited by H(2)O(2) or the thiol oxidant diamide, resulting in Yap1p nuclear accumulation and induction of transcription of its target genes. Here we provide evidence for sensing of H(2)O(2) and diamide mediated by disulfide bond formation in the C-terminal cysteine-rich region (c-CRD), which contains 3 conserved cysteines and the nuclear export signal (NES). The H(2)O(2) or diamide-induced oxidation of the c-CRD in vivo correlates with induced Yap1p nuclear localization. Both were initiated within 1 min of application of oxidative stress, before the intracellular redox status of thioredoxin and glutathione was affected. The cysteine residues in the middle region of Yap1p (n-CRD) are required for prolonged nuclear localization of Yap1p in response to H(2)O(2) and are thus also required for maximum transcriptional activity. Using mass spectrometry analysis, the H(2)O(2)-induced oxidation of the c-CRD in vitro was detected as an intramolecular disulfide linkage between the first (Cys(598)) and second (Cys(620)) cysteine residues; this linkage could be reduced by thioredoxin. In contrast, diamide induced each pair of disulfide linkage in the c-CRD, but in this case the cysteine residues in the n-CRD appeared to be dispensable for the response. Our data provide evidence for molecular mechanisms of redox signal sensing through the thiol-disulfide redox cycle coupled with the thioredoxin system in the Yap1p NES.

Down-regulation of translation driven by hepatitis C virus internal ribosomal entry site by the 3' untranslated region of RNA

The genome of hepatitis C virus (HCV) is a single-stranded RNA of positive polarity that has a poly(U/C) tract followed by a highly conserved 98-nt sequence, termed the X region, in the 3' untranslated region (UTR). To investigate the effect of the 3'UTR on the HCV translation that depends on the internal ribosomal entry site (IRES), we prepared a deletion HCV RNA, MA delta, that lacked the RNA region from nt 1286 to 8785. A series of MA delta RNAs that differ in the primary structure of their 3'UTR, were generated and examined for their translation efficiencies in reticulocyte lysates. Deletion of the poly(U/C) tract and/or stem-loop structure (SL) 3 region of 3'X resulted in enhancement of the translation efficiency. Translation of MA delta RNA was inhibited by the addition of recombinant polypyrimidine tract-binding protein (PTB). A similar inhibition by PTB, however, was observed when an RNA lacking the poly(U/C) tract or SL3 region was used. The inhibitory effect by PTB was not obvious for MA delta (1041) RNA composed of nt 1 to 1041 but MA delta (8928) RNA composed of nt 1 to 1285 and nt 8786 to 8928. These results suggest that the observed down-regulation of HCV translation by the 3'UTR is mediated by some host factor(s) other than PTB, and that a PTB site for inhibition resides in the coding sequence of nt 1042 to 8928 of MA delta RNA.

Nuclear import of the yeast AP-1-like transcription factor Yap1p is mediated by transport receptor Pse1p, and this import step is not affected by oxidative stress

The yeast AP-1-like transcription factor, Yap1p, is essential for the oxidative stress response in budding yeast. Yap1p is located predominantly in the cytoplasm; however, upon imposition of oxidative stress, Yap1p concentrates in the nucleus and activates target genes. Yap1p is constitutively transported in and out of the nucleus. Oxidative stress inhibits the Crm1p/Xpo1p-dependent nuclear export step, resulting in nuclear accumulation of Yap1p. In this study, we examined the mechanism for Yap1p nuclear import, and determined whether the import step is affected by oxidative stress. The nuclear accumulation of Yap1p required the activity of the small GTPase, Ran/Gsp1p. Under conditions in pse1-1 cells carrying a temperature-sensitive mutation of the importin beta family member PSE1/KAP121, nuclear translocation of Yap1p was inhibited dramatically. In an in vitro assay, we showed that Yap1p could directly bind to Pse1p and that this interaction was dissociated by Ran-GTP. These results indicate that Pse1p is the nuclear import receptor for Yap1p. In addition to Pse1p, we suggest that Kap123p, which is homologous to Pse1p, has a minor effect on the nuclear import of Yap1p. Furthermore, we identified the nuclear localization signal of Yap1p and demonstrated that the nuclear import of Yap1p was not affected by oxidative stress.

Comparison of neuropathogenicity of poliovirus type 3 in transgenic mice bearing the poliovirus receptor gene and cynomolgus monkeys

To clarify the similarities of poliovirus infection in cynomolgus monkeys and transgenic mice bearing the poliovirus receptor, TgPVR21, we compared the pathological changes of these animals following intraspinal inoculation of two strains of poliovirus type 3 using immunohistochemical detection of the capsid antigen. All of the monkeys inoculated with 10(6) TCID(50) viruses showed flaccid paralysis 2 or 3 days post-inoculation (p.i.). TgPVR21 mice showed paralysis starting from 2 to 3 days p.i. Histologically, neurons having pyknotic nuclei and eosinophilic cytoplasm and neuronophagia were characteristically observed in both animals, but central chromatolysis was not observed in infected TgPVR21. The median lesion scores in the monkeys and TgPVR21 were well correlated, though the distribution of poliovirus-infected lesions in the central nervous system was different. In both animals the motor neurons and the brainstem nuclei responsible for flaccid paralysis were infected by the virus, while the cerebral cortex and thalamus were infected in the monkeys but not in TgPVR21. These results confirmed the reliability of neurovirulence tests using TgPVR21 as a substitute for monkeys, in respect to the spinal and brainstem lesions of poliovirus type 3.

Expression of scavenger receptor class B type 1 (SR-BI) promotes microvillar channel formation and selective cholesteryl ester transport in a heterologous reconstituted system

In the "selective" cholesteryl ester (CE) uptake process, surface-associated lipoproteins [high density lipoprotein (HDL) and low density lipoprotein] are trapped in the space formed between closely apposed surface microvilli (microvillar channels) in hormone-stimulated steroidogenic cells. This is the same location where an HDL receptor (SR-BI) is found. In the current study, we sought to understand the relationship between SR-BI and selective CE uptake in a heterologous insect cell system. Sf9 (Spodoptera frugiperda) cells overexpressing recombinant SR-BI were examined for (i) SR-BI protein by Western blot analysis and light or electron immunomicroscopy, and (ii) selective lipoprotein CE uptake by the use of radiolabeled or fluorescent (BODIPY-CE)-labeled HDL. Noninfected or infected control Sf9 cells do not express SR-BI, show microvillar channels, or internalize CEs. An unexpected finding was the induction of a complex channel system in Sf9 cells expressing SR-BI. SR-BI-expressing cells showed many cell surface double-membraned channels, immunogold SR-BI, apolipoprotein (HDL) labeling of the channels, and high levels of selective HDL-CE uptake. Thus, double-membraned channels can be induced by expression of recombinant SR-BI in a heterologous system, and these specialized structures facilitate both the binding of HDL and selective HDL-CE uptake.

Chirality organization of ferrocenes bearing podand dipeptide chains: synthesis and structural characterization

A variety of ferrocenes bearing podand dipeptide chains have been synthesized to form an ordered structure in both solid and solution states and have been investigated by 1H NMR, FT-IR, CD, and X-ray crystallographic analyses. Conformational enantiomerization through chirality organization was achieved by the intramolecular hydrogen bondings between the podand dipeptide chains. The single-crystal X-ray structure determination of the ferrocene 2 bearing the podand dipeptide chains (-D-Ala-D-Pro-OEt) revealed two C2-symmetric intramolecular hydrogen bondings between CO (Ala) and NH (another Ala) of each podand dipeptide chain to induce the chirality-organized structure. The molecular structures of the ferrocene 1 composed of the podand L-dipeptide chains (-L-Ala-L-Pro-OEt) and 2 are in a good mirror image relationship, indicating that they are conformational enantiomers. An opposite helically ordered molecular arrangement was formed in the crystal packing of 2 as compared with 1. The ferrocene 2 exhibited induced circular dichroism (CD), which appeared at the absorbance of the ferrocene moiety. The mirror image of the CD signals between 1 and 2 was observed, suggesting that the chirality-organized structure via intramolecular hydrogen bondings is present even in solution. The ferrocene 4 bearing the podand dipeptide chains (-Gly-L-Leu-OEt) also showed an ordered structure in the crystal based on two intramolecular hydrogen bondings between CO (Gly) and NH (another Gly) of each podand dipeptide chain, together with intermolecular hydrogen bondings between CO adjacent to the ferrocene unit and NH (neighboring Leu) to create the highly organized self-assembly. A different self-assembly was observed in the crystal of the ferrocene 5 composed of the podand dipeptide chains (-Gly-L-Phe-OEt), wherein each molecule is bonded to two neighboring molecules through two pairs of symmetrical intermolecular hydrogen bonds to form a 14-membered intermolecularly hydrogen-bonded ring. These ordered structures based on the intramolecular hydrogen bondings in the solution state are also confirmed by 1H NMR and FT-IR.

Expression and microvillar localization of scavenger receptor class B, type I (SR-BI) and selective cholesteryl ester uptake in Leydig cells from rat testis

This study investigates the relationship between the high density lipoprotein (HDL) receptor (scavenger receptors, SR-BI and SR-BII), selective lipoprotein-cholesteryl ester uptake, and testosterone production in Leydig cells of control, hypocholesterolemic and gonadotrophic hormone (hCG) treated rats. Leydig cells from mature control rats show poor efficiency in incorporation of labeled HDL-cholesteryl esters into testosterone, poor selective uptake of lipoprotein lipids overall, and a dramatic reduction of circulating levels of lipoproteins has no apparent effect on testosterone production or expression of intracellular enzymes synthesizing cholesterol. Leydig cells from control rats show minimal levels of SR-BI and SR-BII. However, similarly aged rats treated with hCG for several days undergo changes consistent with hormone-desensitization. Despite the resulting low levels of testosterone production, SR-BI levels are dramatically increased, Leydig cells now efficiently internalize HDL-supplied cholesteryl esters by the selective cholesterol uptake process, and various other cholesterol-sensitive genes of the cells are up-regulated. Only SR-BII expression remains negligible and unchanged throughout this period. It is of interest that Leydig cell SR-BI of hCG-treated rats is localized in surface microvilli, but is present also in an elaborate and complex channel system within the cytoplasm of the cells. In summary, Leydig cells differ from other rat steroidogenic cells in not depending on exogenous lipoprotein-cholesterol during periods of normal steroid hormone production. However, trophic hormone desensitization is accompanied by increased Leydig cell SR-BI expression and increased selective HDL-cholesteryl ester uptake, presumably in preparation for renewed testosterone production.

HeLa cell transformants overproducing mouse metallothionein show in vivo resistance to cis-platinum in nude mice

Plasmid pSV2MT-I encoding mouse metallothionein-I (MT-I) designed to be expressed under the control of an SV40 promoter was introduced into human HeLa S3 cells. Several transformants (HeLa/MTH) carrying multi-copies of mouse MT-I cDNA in their genomes were isolated. These transformants produced 4 to 20-fold larger amounts of MT than their parent cells. The MT levels in HeLa/MTH were well correlated with the extent of resistance to cadmium, but not with that to cis-platinum (cis-DDP) in vitro. To study the role of MT in resistance to cis-DDP in vivo, nude mice were inoculated subcutaneously with two independent HeLa/MTH clones. MT levels in these tumors were about 3-fold higher than those in the parental cells. The growth of tumors derived from either HeLa/MTH clone was not inhibited in the presence of 15 micromol/kg of cis-DDP, which completely inhibited the growth of tumors derived from the parental HeLa cells. These data strongly suggest that the elevated level of MT confers resistance to cis-DDP in vivo but not in vitro. Thus, the results of this study indicate that in vitro determinations of the influence of MT on cis-DDP resistance may underestimate its importance in in vivo situations.

Multiple pathways for establishment of poliovirus infection

Poliovirus (PV) infects susceptible cells through poliovirus receptor (PVR), which functions to bind virus and to convert its conformation. To study early infection process of PV, infection systems were employed using in vitro cultured cells and in vivo neural pathway of PVR transgenic (Tg) mice. For in vitro study, mouse L cells were established expressing mouse high affinity Fc gamma receptor molecules, and used them as in vitro PV infection system. PV infection was mediated, albeit inefficiently, by mouse anti-PV monoclonal antibodies (mAbs; IgG2a subtypes) that did not show an activity to convert PV (160S) to 135S particle. The infection efficiency was enhanced when PVR-IgG2a, a chimera molecule consisting of the extracellular moiety of PVR and the Fc portion of mouse IgG2a, was used for anti-PV mAbs. Virion conformational change to 135S particle was induced by PVR-IgG2a. For in vivo study, intramuscular (i.m.) inoculation of PV into the calves of PV-sensitive Tg mice was employed. PV-related materials recovered from the sciatic nerve, after the i.m. inoculation, were mainly composed of intact 160S virion particle, although this neural pathway appeared to be dependent on PVR. These results suggested that some specific interaction(s) of PVR to PV beyond its binding activity was important to enhance infectivity of PV in in vitro cultured cells, and that PV uncoating occurs after retrograde axonal transport of the virus through the sciatic nerve of Tg mice. Thus, PV infection may be established by any of these several pathways. reserved.

Isolation and molecular characterization of a poliovirus type 1 mutant that replicates in the spinal cords of mice

The Mahoney strain of poliovirus type 1 (OM) is generally unable to cause paralysis in mice. We isolated a mouse-adapted mutant, PV1/OM-SA (SA), from the spinal cord of a mouse that had been intracerebrally inoculated with OM. SA showed mouse neurovirulence only with intraspinal inoculation, and the infected mice developed a flaccid paralysis, which was indistinguishable from that observed in poliovirus-sensitive transgenic mice inoculated with OM. SA antigens were detected in neurons of the spinal cords of the infected mice. Nucleotide (nt) sequence analysis revealed 9 nt changes on the SA genome, resulting in three amino acid (a.a.) substitutions, i.e., one each in the capsid proteins VP4 and VP1 and in the noncapsid protein 2C. To identify the key mutation site(s) for the mouse neurovirulence, virus recombinants between OM and SA were constructed by using infectious cDNA clones of these two viruses and tested for their mouse neurovirulence after inoculation via an intraspinal route. The results indicated that a mutation at nt 928 (replacement of A with G), resulting in a substitution of Met for Ile at a.a. 62 within VP4, was responsible for conferring the mouse neurovirulence phenotype of the mutant SA. The mutation in VP4 may render the virus accessible to a molecule that acts as a virus receptor and is located on the surfaces of neurons of the mouse spinal cord. This molecule appears not to be expressed in the mouse brain.

Nectin/PRR: an immunoglobulin-like cell adhesion molecule recruited to cadherin-based adherens junctions through interaction with Afadin, a PDZ domain-containing protein

We have isolated a novel actin filament-binding protein, named afadin, localized at cadherin-based cell-cell adherens junctions (AJs) in various tissues and cell lines. Afadin has one PDZ domain, three proline-rich regions, and one actin filament-binding domain. We found here that afadin directly interacted with a family of the immunoglobulin superfamily, which was isolated originally as the poliovirus receptor-related protein (PRR) family consisting of PRR1 and -2, and has been identified recently to be the alphaherpes virus receptor. PRR has a COOH-terminal consensus motif to which the PDZ domain of afadin binds. PRR and afadin were colocalized at cadherin-based cell-cell AJs in various tissues and cell lines. In E-cadherin-expressing EL cells, PRR was recruited to cadherin-based cell-cell AJs through interaction with afadin. PRR showed Ca2+-independent cell-cell adhesion activity. These results indicate that PRR is a cell-cell adhesion molecule of the immunoglobulin superfamily which is recruited to cadherin-based cell-cell AJs through interaction with afadin. We rename PRR as nectin (taken from the Latin word "necto" meaning "to connect").

Identification of a new element for RNA replication within the internal ribosome entry site of poliovirus RNA

Several mutants of the Mahoney strain of poliovirus type 1 have been generated by introducing mutations into the stem-loop II (SLII) structure within the internal ribosomal entry site (IRES). Four of these mutants (SLII-1, -4, -5 and -6 mutants) have been characterized previously and are host-range mutants that replicate well in human HeLa cells but not in mouse cells. Two deletion mutants, SLII-2 and SLII-3, were non-viable, even in HeLa cells. It is now reported that SLII-2 was defective in genome RNA synthesis and viral protein synthesis, while SLII-3 was defective only in viral protein synthesis. These results indicate that the SLII region contains a cis-element for RNA replication as well as for IRES-dependent translation and that these two functions lie at the same sites within the SLII region. The host cellular factors that interacted with wild-type SLII and mutant SLII-2 and SLII-3 RNAs were different, suggesting that different host-factor binding regulates expression of mutant phenotypes.

Intracellular redistribution of truncated La protein produced by poliovirus 3Cpro-mediated cleavage

The La autoantigen (also known as SS-B), a cellular RNA binding protein, may shuttle between the nucleus and cytoplasm, but it is mainly located in the nucleus. La protein is redistributed to the cytoplasm after poliovirus infection. An in vitro translation study demonstrated that La protein stimulated the internal initiation of poliovirus translation. In the present study, a part of the La protein was shown to be cleaved in poliovirus-infected HeLa cells, and this cleavage appeared to be mediated by poliovirus-specific protease 3C (3Cpro). Truncated La protein (dl-La) was produced in vitro from recombinant La protein by cleavage with purified 3Cpro at only one Gln358-Gly359 peptide bond in the 408-amino-acid (aa) sequence of La protein. The dl-La expressed in L cells was detected in the cytoplasm. However, green fluorescence protein linked to the C-terminal 50-aa sequence of La protein was localized in the nucleus, suggesting that this C-terminal region contributes to the steady-state nuclear localization of the intact La protein in uninfected cells. The dl-La retained the enhancing activity of translation initiation driven by poliovirus RNA in rabbit reticulocyte lysates. These results suggest that La protein is cleaved by 3Cpro in the course of poliovirus infection and that the dl-La is redistributed to the cytoplasm. dl-La, as well as La protein, may play a role in stimulating the internal initiation of poliovirus translation in the cytoplasm.