Search

The study aimed to investigate the extended effects and interrelations of corneal biomechanics, corneal optical density (COD), corneal thickness (CT), and intraocular pressure (IOP) following cataract surgery. Sixteen eyes were analyzed prospectively. The Corneal Visualization Scheimpflug Technology (Corvis ST) device assessed corneal biomechanics, while the Pentacam AxL ® (Pentacam) measured COD and CT. Postoperative data were collected around six months after surgery, with a subgroup analysis of data at nine months. The Pearson correlation was used to examine the relationship between surgical-induced changes in corneal biomechanics and COD. At six months, significant postoperative differences were observed in various biomechanical indices, including uncorrected IOP (IOPuct) and biomechanics-corrected IOP (bIOP). However, many indices lost statistical significance by the nine-month mark, suggesting the reversibility of postoperative corneal changes. Postoperative COD increased at the anterior layer of the 2-6 mm annulus and incision site. The changes in COD correlated with certain biomechanical indices, including maximal (Max) deformative amplitude (DA) and stiffness parameter (SP). In conclusion, despite significant immediate postoperative changes, corneal biomechanics, COD, and IOP experienced a gradual recovery process following cataract surgery. Clinicians should maintain vigilance for any unusual changes during the short-term observation period to detect abnormalities early.

Purpose: To compare corneal haze between active ulcer and healed scarring using a Scheimpflug densitometry., Materials and Methods: A prospective longitudinal study enrolled 30 patients (30 eyes) with ulcerative keratitis (UK). Each subject's corneal optical density (COD) was measured with a Scheimpflug corneal densitometry, Pentacam® AXL (Oculus GmbH, Wetzlar, Germany), at the active ulcerative and complete scarring stage. The COD data were analyzed through distinct methods (inbuilt, sorted annular partitions, and ulcer-matching densitometric maps). We compared different CODs to select the better index for clinically monitoring the transition from corneal ulceration to healed scar., Results: The CODs of the periphery (P = 0.0024) and outside of the active ulcer (P = 0.0002) significantly decreased after scarring. Partitioning the cornea into different depths and annular zones, the anterior layer, center layer, and the 2-6 mm annular zone had a more remarkable COD decrease after scar formation. The 3rd-sorted COD in the anterior layer revealed the highest area under the receiver-operating characteristic curves (0.709), in which 90% of subjects had COD reduction during the ulcer-to-scar transition., Conclusions: Aside from subjective judgment based on clinical signs, the Scheimpflug tomography-based densitometry could provide objective and efficient monitoring of the corneal opacity evolution in UK patients. Because the 3rd-sorted annular COD is a better index than the inbuilt or mapping CODs in differentiating active ulcers from healed scars, this COD could be a clinically promising parameter to monitor the progression of UK patients., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Although Coronavirus disease 2019 (COVID-19) vaccinations are generally recommended for persons with epilepsy (PwE), a significant vaccination gap remains due to patient concerns over the risk of post-vaccination seizure aggravation (PVSA). In this single-centre, retrospective cohort study, we aimed to determine the early (7-day) and delayed (30-day) risk of PVSA, and to identify clinical predictors of PVSA among PwE. Adult epilepsy patients aged ≥18 years without a history of COVID-19 infection were recruited from a specialty epilepsy clinic in early 2022. Demographic, epilepsy characteristics, and vaccination data were extracted from a centralized electronic patient record. Seizure frequency before and after vaccination, vaccination-related adverse effects, and reasons for or against vaccination were obtained by a structured questionnaire. A total of 786 PwEs were included, of which 27.0% were drug-resistant. At the time of recruitment, 74.6% had at least 1 dose of the COVID-19 vaccine. Subjects with higher seizure frequency ( p < 0.0005), on more anti-seizure medications ( p = 0.004), or had drug-resistant epilepsy ( p = 0.001) were less likely to be vaccinated. No significant increase in seizure frequency was observed in the early (7 days) and delayed phases (30 days) after vaccination in our cohort. On the contrary, there was an overall significant reduction in seizure frequency 30 days after vaccination (1.31 vs. 1.89, t = 3.436; p = 0.001). This difference was seen in both types of vaccine (BNT162b2 and CoronaVac) and drug-resistant epilepsy, but just missed significance for the second dose (1.13 vs. 1.87, t = 1.921; p = 0.055). Only 5.3% had PVSA after either dose of vaccine. Higher pre-vaccination seizure frequency of ≥1 per week (OR 3.01, 95% CI 1.05-8.62; p = 0.04) and drug-resistant status (OR 3.32, 95% CI 1.45-249 7.61; p = 0.005) were predictive of PVSA. Meanwhile, seizure freedom for 3 months before vaccination was independently associated with a lower risk of PVSA (OR 0.11, 95% CI 0.04-0.28; p < 0.0005). This may guide epilepsy treatment strategies to achieve better seizure control for at least 3 months prior to vaccination. As COVID-19 shifts to an endemic phase, this study provides important data demonstrating the overall safety of COVID-19 vaccinations among PwE. Identification of high-risk patients with subsequent individualized approaches in treatment and monitoring strategies may alleviate vaccination hesitancy among PwE.

This study conducted a systematic scoping review to collect definitions and explanations of esports and its related concepts in the existing literature. A thematic coding approach was used to screen possible disagreements and issues between the different characteristics of esports as presented in the existing definitions. Based on a critical discussion, the results of the coding were combined with the objective facts of the current esports industry and theories from similar fields to reconstruct the construction of an esports definition. In addition, the relationship between esports and its related concepts was discussed based on the proposed esports definition structure. The proposed esports criteria can help avoid misunderstandings and confusion in future studies regarding the research subjects related to esports and propose standardized usage of relevant terms in the field of esports research., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

Background: Invasive fungal rhinosinusitis (IFS) with orbital complications has remained a challenging disease over the past few decades. Only a few studies have been conducted to investigate the factors associated with orbital complications in fungal rhinosinusitis (FRS). We aimed to review the characteristics between IFS and non-invasive fungal rhinosinusitis (NIFS) and determine clinical factors associated with orbital complications and overall survival., Methods: A multi-institutional database review study was conducted using the Chang Gung Research Database (CGRD) from January 2001 to January 2019. We identified FRS patients using International Classification of Diseases diagnosis codes and SNOMED CT. We categorized patients into IFS and NIFS groups and analyzed the demographic data, underlying diseases, clinical symptoms, laboratory data, image findings, fungal infection status, and survival outcomes., Results: We included 1624 patients in our study, with 59 IFS patients and 1565 NIFS patients. The history of an organ or hematopoietic cell transplantation had a significant prognostic effect on the survival outcomes, with surgical intervention and high hemoglobin (Hb) and albumin levels recognized as positive predictors. Posterior ethmoid sinus involvement, sphenoid sinus involvement, facial pain, blurred vision, and periorbital swelling were risk factors of orbital complications., Conclusions: In NIFS patients, orbital complications were found to be associated with old age, a high WBC count, high blood glucose, and a high CRP level. For the risk factors of orbital complications in IFS patients, posterior ethmoid sinus involvement, sphenoid sinus involvement, facial pain, blurred vision, and periorbital swelling were recognized as predictors. Among IFS patients, a history of organ or hematopoietic cell transplantation was a risk factor for poor survival, while, conversely, surgical intervention and high Hb and albumin levels were related to improved survival. As predictors of orbital complications in IFS patients, posterior ethmoid sinus involvement, sphenoid sinus involvement, facial pain, blurred vision, and periorbital swelling upon the first visit should raise attention, with close monitoring.

Background: Removal of the surrounding bone during dacryocystorhinostomy may present a higher risk of skull base injury in patients with frontal sinus aplasia. We used sinus plain films to predict cases with a greater risk of a reduced skull base distance in dacryocystorhinostomy. Methods: Sinus plain films and computed tomography data from patients were retrospectively evaluated. The frontal sinus was classified as normal, hypoplastic, or aplastic according to Waters’ view. Correlations of the frontal sinus roof-supraorbital margin (F-O) and the frontal sinus roof-nasion (F-N) distances on plain film with the closest lacrimal sac-anterior skull base (LS-ASB) distance measured on computed tomography images were assessed. Results: We evaluated 110 patients. In total, 16 (11.8%) patients had frontal sinus aplasia, of whom 6 (2.7%) had bilateral and 10 (9.1%) had unilateral aplasia. Sides with frontal sinus aplasia based on Waters’ view had a shorter median LS-ASB distance than normal or hypoplastic sides. The F-O and F-N distances in Waters’ view were significantly positively correlated with the computed tomographic LS-ASB distance. The F-O margin and F-N distance thresholds for predicting an LS-ASB distance < 10 mm, considered a risky distance, were 11.6 and 14.4 mm, respectively, with sensitivities of 100% and 91.7%, and specificities of 76% and 82.7%, respectively. Conclusions: The LS-ASB distance is closer on aplastic frontal sinus sides. Waters’ view on plain sinus films can provide a fast and inexpensive method for evaluating the skull base distance and sinonasal condition during planning for dacryocystorhinostomy.

To pursue the least corneal implication during cataract surgery, this study aimed to monitor corneal wound injury after cataract surgery with a novel method. The prospective cohort study involved thirty-two patients, who were assessed by a Scheimpflug tomography AxL ® (Oculus GmbH, Wetzlar, Germany) via the following two kinds of indices: whole corneal optical density (COD) and corneal thickness (CT), two weeks before and one month after cataract surgery. The results of the COD revealed that corneal annuli 0.0-2.0 mm and 2.0-6.0 mm, and the average and maximal values at the incisional site significantly increased postoperatively. Also, the anterior and central stroma of 0.0-2.0 mm, and all three depths of 2.0-6.0 mm, increased remarkably after the operation. For the CT, all ranges of diameters plus incisional sites showed significant increases postoperatively. Furthermore, we analyzed the differences (delta) of COD and CT between pre- and post-operation, and found significant correlations between the delta of COD and the delta of CT, regarding annuli 0.0-2.0 mm, 2.0-6.0 mm, and 6.0-10.0 mm, but no correlation at the incisional site, with either average density or maximal density, was detected. We concluded that whole COD and CT, especially at the central zones of the cornea (annulus < 6 mm), are both valuable parameters in the assessment of corneal damage post-cataract surgery, and are independent indices at the incisional site.

A territory-wide retrospective observational study was conducted in Hong Kong between January 23 to April 22, 2020 to demonstrate changes in pediatric seizure-related accident and emergency department (A&E) visits during the COVID-19 pandemic. Parallel periods from 2015 to 2019 were used as control. All-cause A&E attendances in all paediatric age groups decreased significantly during the study period. Seizure-related attendances decreased across all pediatric age-groups in 2020 (RR 0.379, 95% CI 0.245-0.588), with a disproportionately large decrease in the 0-6 years age group (RR 0.303, 95% CI 0.174-0.526) compared with the 7-18 years age group (RR 0.534, 95% CI 0.393-0.719). Decrease in RTI-related A&E attendances was also more drastic in the 0-6 age group. The two time trends are congruent in the 0-6 years but not the 7-18 years age group. Such a trend is suggestive of the usefulness of infection control measures in seizure prevention, especially amongst young children., Competing Interests: Declaration of competing interest All authors have nothing to disclose., (Copyright © 2020. Published by Elsevier B.V.)

This study aims at determining the thickness of the tear lipid layer (LL) observed from a placido-disc-based tear film analyzer. We prospectively collected reflections of placido-disk LL images using a tear film analyzer (Keratograph ® 5M, Oculus) from subjects with dry eye symptoms. The LL thickness (LLT) over the inferior half of the cornea was estimated with the use of interference color analysis and the preprocessing of images with and without ring segmentation were obtained and analyzed. Moreover, LLTs before and after 1 h of applying topical ointment (Duratears, Alcon) were compared to validate the estimation of LLT. Our results suggested that the tear LLT can be assessed using a placido-disk-based tear film analyzer and interference color analysis. We verified a high correlation between non-segmented and segmented LL images and estimated LLT increase after applying ointment. In addition, we concluded that LLT can be evaluated by direct interference analysis without segmentation preprocessing.

Clinical usage of botulinum neurotoxin (BoNT) in ophthalmology has dramatically increased since the 1980s and has become one of the most widely used agents for treating facial movement disorders, autonomic dysfunction and aesthetic wrinkles. Despite its high efficacy, there are some complications with periocular BoNT injections due to its chemodenervation effect. Among these, there is still controversy over the BoNT effect on tear film homeostasis and the ocular surface. A periocular BoNT injection could dry the eye by reducing tear production of the lacrimal gland and increase tear evaporation due to potential eyelid malposition and abnormal blinks. On the contrary, the injection of BoNT in the medial eyelids could treat dry eye disease by impairing lacrimal drainage. Regarding the ocular surface change, corneal astigmatism and high-order aberrations may decrease due to less eyelid tension. In conclusion, the entire awareness of the effect of BoNT and the patients' ocular condition is crucial for successful and safe results.

Background: A standard post-concomitant radiochemotherapy involving adjuvant temozolomide (TMZ) was stopped after 6 cycles for high-grade gliomas (HGG). Several studies demonstrated that prolonged TMZ treatment increased survival for these patients., Methods: This retrospective study aimed to compare changes in tumor volume during and after adjuvant TMZ treatment and overall survival (OS)., Results: There were 90 patients were administered adjuvant TMZ treatment. Comparing average tumor volume changes during TMZ treatment and after TMZ was stopped, a significant decrease in tumor volume was observed during TMZ treatment in the total patient population, the anaplastic astrocytoma (AA) group, and the glioblastoma multiforme (GBM) group (P ≤ 0.001, P = 0.042, and P = 0.005, respectively). Median overall survival was 78.4 weeks, which was significant regarding the surgical tumor resection rate (r = 0.241; P = 0.04) and total TMZ treatment cycles (r = 0.631; P ≤ 0.001)., Conclusions: During adjuvant TMZ treatment, tumor volume decreased significantly (P = 0.042, and P = 0.005, respectively) in patients with GBM and AA. Prolonged TMZ administration improved OS, without increased toxicity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The aim of this study was to investigate changes in the tear film lipid layer thickness (LLT) and aqueous tear production after botulinum neurotoxin A (BoNT) injection in patients with benign essential blepharospasm (BEB) and hemifacial spasm (HFS). Eleven and six patients with BEB and HFS, respectively, who received BoNT injection were consecutively enrolled in this prospective study. The blepharospasm disability index (BSDI), blink pattern, dry eye symptoms, Schirmer test 1 findings, LLT, eyelid performance, and corneal integrity were evaluated before and after treatment. Both BEB and HSF patients experienced remarkable relief from spasms and ocular discomfort after BoNT injection. LLT, the partial blink rate, the snap-back time, the lid distraction distance, and lateral canthal laxity were significantly increased at 1 month after treatment. There were no significant changes in Schirmer test 1 findings and meibomian gland dropout. Our findings suggest that LLT, a decisive factor for tear film stability, significantly increases at 1 month after BoNT injection for BEB and HFS. A decrease in BSDI and an increase in the snap-back time may contribute to the increase in LLT; this mechanism is probably responsible for the relief from dryness after BoNT injection in patients with facial movement disorders.

Background: To investigate function and morphology of the meibomian gland (MG) in patients with thyroid eye disease (TED)., Methods: In this prospective case series study, patients with unilateral or bilateral TED were consecutively enrolled. The diagnosis of TED was based on the typical orbital findings and/or radiographic evidence. The disease activity of TED was classified according to the clinical activity score (CAS). Degrees of lagophthalmos and exophthalmos, blinking rates, and results of the Schirmer test 1 were also recorded. All patients completed the SPEED questionnaire and underwent MG assessment, including lipid layer thickness (LLT), MG dropout (MGd), and MG expression., Results: In total 31 eyes from 17 patients with unilateral or bilateral TED were included. Patients were divided into inactive TED (CAS 0-1; 20 eyes from 11 patients) and active TED (CAS 2-3, 11 eyes from 6 patients) groups. MGd was significantly more severe in the active TED than the inactive TED group [Median (Inter-quartile region): 3.0 (2.0-3.0) vs. 2.0 (1.0-2.0) degree, P = 0.04]. However, patients with active TED had thicker LLT than those with inactive TED (90.0 [80.0-100.0] vs. 65.0 [47.8-82.5] nm, P = 0.02), and LLT was positively correlated with lagophthalmos (r = 0.37, P = 0.04)., Conclusions: Patients with active TED had more severe MGd, but thicker LLT. Active TED may cause periglandular inflammation of MGs, leading to MGd, but compensatory secretion from residual MGs and lagophthalmos-induced forceful blinking might temporarily release more lipids over the tear film.

Purpose: To evaluate a bacterial dot hybridization (BDH) assay for the diagnosis of bacterial keratitis (BK)., Methods: Sixty-one qualified corneal scrapings from 61 patients with suspected microbial keratitis were collected consecutively and prospectively. Among the 61 patients, 16 cases were BK and 45 cases were non-BK, including fungal keratitis, viral keratitis, parasitic keratitis, and non-microbial keratitis. Molecular diagnosis of BK in these corneal scrapes was performed using the BDH assay with three universal bacterial probes (PB1, PB2, and PB3) and three genus-specific probes (Aci, Klb, and Psu) to detect Acinetobacter , Klebsiella , and Pseudomonas , respectively. Signals were standardized after grayscale image transformation for objective validation using receiver operating characteristic (ROC) curves., Results: The standardized intensities for the three universal probes differed statistically significantly between the BK group and the non-BK group. Based on the ROC curves, the sensitivities of PB1, PB2, and PB3 were 81.3%, 81.3%, and 93.8%, and the specificities were 71.1%, 88.9%, and 91.1%, respectively. The sensitivity and specificity of the Psu probe were 92% and 100%, respectively, while those of the Aci and Klb probes could not be estimated because there were no BK cases caused by Acinetobacter spp. or Klebsiella spp., Conclusions: The BDH assay is an effective molecular approach to improve the diagnosis of BK. Because the bias from bacterial contamination on the ocular surface can be minimized with signal standardization, the assay has the potential to be adopted for routine clinical practice.

Objectives: Aim of this study was to demonstrate the feasibility, safety, and short-term outcome of left atrial appendage (LAA) closure with a new generation LAA closure device., Background: The Amulet device (AGA, St Jude Medical, Minneapolis, MN) is a new generation of the amplatzer cardiac plug (ACP), specifically designed for LAA closure. This new version is designed to facilitate the implantation process and minimize procedural or device-related complications., Methods: The device was implanted in 17 patients with nonvalvular atrial fibrillation (AF). Clinical data were obtained at baseline, during the procedure, at discharge, at 30 and 90 days., Results: All devices were implanted successfully. Device sizes ranged from 20 mm to 31 mm. A 12 French (Fr) or 14 Fr delivery sheath was used depending on the selected device size. Full and partial recapture was performed in 1 case and 3 cases, respectively. There was 1 procedure-related pericardial effusion successfully managed with pericardiocentesis. There was no device embolization. The mean length of stay was 2.1 ± 0.3 days. At 90 days, there were no deaths, strokes, systemic thromboembolism, or bleeding complications. There was no device-related thrombus or pericardial effusion at 90-day TEE. In 2 of the 17 patients minimal peridevice flow (smaller than 2 mm) was present., Conclusions: The Amulet device, which has new novel features as compared with the first generation ACP, is a feasible option for LAA closure. From our initial experience, implantation of the Amulet is associated with high success rate and good short-term outcome., (© 2014 Wiley Periodicals, Inc.)

Objective: The aims of this study were to investigate the quantitative relationship between pituitary macroadenoma size and degree of visual impairment, and assess visual improvement after surgical resection of the tumor., Methods: The medical records of patients with pituitary adenoma, who had undergone trans-sphenoidal adenectomy between January 2009 and January 2011, were reviewed. Patients underwent an ocular examination and brain MRI before and after surgery. The visual impairment score (VIS) was derived by combining the scores of best-corrected visual acuity and visual field. The relationship between VIS and tumor size/tumor type/position of the optic chiasm was assessed., Results: Seventy-eight patients were included (41 male, 37 female). Thirty-two (41%) patients experienced blurred vision or visual field defect as an initial symptom. Receiver operating characteristic curve analysis showed that tumors <2.2 cm tended to cause minimal or no visual impairment. Statistical analysis showed that 1) poor preoperative vision is related to tumor size, displacement of the optic chiasm in the sagittal view on MRI and optic atrophy, and 2) poorer visual prognosis is associated with greater preoperative VIS. In multivariate analysis the only factor significantly related to VIS improvement was increasing pituitary adenoma size, which predicted decreased improvement., Conclusion: Results from this study show that pituitary adenomas larger than 2 cm cause defects in vision while adenomas 2 cm or smaller do not cause significant visual impairment. Patients with a large macroadenoma or giant adenoma should undergo surgical resection as soon as possible to prevent permanent visual loss.

Motivated by biometric applications, we analyze oscillatory flow in a cone-and-plate geometry. The cone is rotated in a simple harmonic way on a stationary plate. Based on assuming that the angle between the cone and plate is small, we describe the flow analytically by a perturbation method in terms of two small parameters, the Womersley number and the Reynolds number, which account for the influences of the local acceleration and centripetal force, respectively. Working equations for the shear stresses induced both by laminar primary and secondary flows on the plate surface are presented.

Background: IgA antibody titers to the Epstein-Barr virus (EBV) viral capsid antigen (EBV IgA-VCA) and to the EBV early antigen (EBV IgA-EA) are used to screen for nasopharyngeal carcinoma (NPC). This study evaluates the sensitivity and specificity of EBV IgA-VCA and EBV IgA-EA titers in screening patients for NPC and in those diagnosed with NPC at our institution., Methods: The NPC status was determined for all patients who had their EBV IgA-VCA and EBV-IgA EA titers measured over a 3-year period, and the sensitivity and specificity were calculated., Results: Five thousand one hundred ninety-six samples were analyzed. NPC was diagnosed in 215 patients. The sensitivity and specificity of a raised EBV IgA-VCA titer (> or =1:5) for diagnosing NPC were 89% and 80%, respectively, with a raised EbV IgA-EA titer (> or =1:5) having a sensitivity and specificity of 63% and 97%, respectively., Conclusions: Although the EBV IgA-VCA titer is sensitive for the diagnosis of NPC, it should not be used as the sole means of screening for NPC in a population in which NPC is endemic., (Copyright 2004 Wiley Periodicals, Inc.)

Background: Establishment of norms for hand strength is emerging worldwide and is both important and necessary in public health and hand surgery. The purpose of this study was to establish normative data for hand grip and key pinch strength for 15- to 22-year-old Chinese students., Methods: The Jamar dynamometer was used to measure grip strength and the Jamar pinch gauge to measure key pinch strength. All subjects were free of disease or injury that might affect hand strength. All complementary factors such as age, sex, height, weight, dominant hand for writing and exercise were recorded. The influences of injury, exercise and living habits on the performance of hand strength were also examined., Results: Out of a total of 2,982 students examined, there were nine men (0.39%) who used the left hand for writing, 143 men (6.27%) who used the left hand during exercise, two women (0.28%) who wrote with the left hand and 26 women (3.70%) who used the left hand during exercise. The mean grip and key pinch strength of the left hand was about 90% that of the right hand. The mean grip and key pinch strength of the women was about 60% that of men., Conclusions: A strong correlation between the right hand and the left hand in grip and key pinch strength was found. Whether nonanthropometric factors may affect hand strengths was explored as well.

We describe the case of a patient who was originally diagnosed with an antrochoanal polyp. During avulsion of the mass by endoscopic polypectomy, it was discovered that the stalk of the polyp actually arose from the mucosa of the right superior turbinate rather than from the mucosa of the maxillary antrum. A diagnosis of choanal polyp was made.

Data are presented on a case of cutaneous furuncular myiasis in a Jamaican resident. This condition is virtually unknown in the Caribbean, but is endemic in Central and South America. The infection, which was caused by Dermatobia hominis, was acquired in Belize and was misdiagnosed and treated as infected insect bites. Cutaneous furuncular myiasis should be considered in patients with sub-acute inflammatory nodular skin lesions with a history of recent travel to endemic countries.

Changes in transfer ribonucleic acids during aging could be caused by alterations in regulation or mutation and give rise to slower and less accurate protein synthesis. Rodent liver parenchymal cells, purified from disaggregated livers, do decrease in ability to incorporate labeled amino acids during aging. Moreover, old rodents have a rapidly degraded fraction of liver soluble RNA which is absent from middle-aged animals. In addition, tRNAs purified from old unfractionated liver cannot be acylated as well as from young. High speed supernatant tRNAs from old and young liver are quite similar in acylation capacity. Analysis indicates that a defective subfraction of tRNA may be bound to the ribosomal fraction of the liver cell. Some evidence indicates that base modification levels differ in young and old rodent liver. Shifts in the proportions of lysine and serine isoacceptors during aging are consistent with this idea. One isoacceptor change is an increase in tRNAlys4, which is correlated with cell division capacity in other systems.