The molecular functions of Biodentine and mineral trioxide aggregate in lipopolysaccharide-induced inflamed dental pulp cells.

AIM: To explore the proliferation, adhesion and differentiation response and the underlying mechanisms that occur in lipopolysaccharide (LPS)-induced inflamed dental pulp cells (DPCs) in contact with Biodentine and mineral trioxide aggregate (MTA). METHODOLOGY: The DPCs were isolated from three healthy donors and named DPC-H1 to DPC-H3. The DPCs were pre-cultured with 2 or 5 µg mL-1 LPS for 24 h to induce inflammation. The expression of inflammation marker miR-146a was detected by q-PCR. The normal and LPS-induced DPCs were further treated with 0.14 mg mL-1 Biodentine or 0.13 mg mL-1 MTA for 24 h. MTT assay and adhesion assay were used to analyse the changes of cell phenotypes. DSPP, AKT and ERK expressions were detected by Western blotting. The data were analysed by Mann-Whitney test or two-way anova. Differences were considered statistically significant when P < 0.05. RESULTS: In LPS-induced DPCs, Biodentine and MTA treatment neither induced nor aggravated LPS-induced inflammation, but their presence did increase the expression of the odontogenic differentiation marker DSPP. Under 2 or 5 µg mL-1 LPS-induced inflammation, Biodentine and MTA promoted the proliferation of DPC cells, and significantly in DPC-H2 (P < 0.0001 for both reagents). With the treatment of 2 µg mL-1 LPS, the cell adhesion of DPCs on the fibronectin-coated culture plates was increased significantly by Biodentine (P = 0.0413) and MTA (P < 0.0001). Biodentine and MTA regulated cell adhesion on the fibronectin-coated culture plates (P < 0.0001 for both reagents) and proliferation (P < 0.0001 for both reagents) via the AKT pathway. However, the AKT pathway was not involved in the expression of DSPP induced by Biodentine and MTA. CONCLUSION: Biodentine and MTA enhanced the proliferation, adhesion and differentiation of LPS-induced DPCs. The proliferation and adhesion process induced by Biodentine and MTA was via the AKT pathway. However, the cellular differentiation process might not use the same pathway, and this needs to be explored in future studies.

Integration of imaging and molecular approaches in selective fetal reduction in twin pregnancies with one carrying a pathogenic genomic aberration.

BACKGROUND/PURPOSE: With the evolution of assisted fertility and prenatal diagnostic technology, the prevalence of multi-fetal pregnancy increased, followed by the demand for prenatal intervention if genomic aberration was detected. How to distinguish the affected foetus from the normal co-twin before selective fetal reduction is therefore challenging. OBJECTIVES: We retrospectively reviewed the cases of dichorionic twins at our centre during 2004-2018, where selective fetal reduction was requested because one foetus carried a pathogenic genomic aberration. Five cases were enrolled, including three foetuses with trisomy 21, one foetus with microduplication and one foetus with microdeletion disorders. METHOD: We labelled the affected foetus by prenatal ultrasound and rapid molecular tools. For the twins without discriminating sonographic features (e.g., the same gender and no distinct placentae), interphase fluorescence in situ hybridization, rapid microarray and short tandem repeat markers were applied to identify the affected foetus. RESULTS: Selective fetal reduction was allocated accurately for all individuals. Two cases delivered at term, while two delivered preterm, and one developed fetal loss of the co-twin. CONCLUSION: We proposed a working scheme of integrating imaging and molecular techniques to correctly identify the affected co-twin before selective fetal reduction to ensure the accuracy of the identification.

Transformation of excess mortality in people with schizophrenia and bipolar disorder in Taiwan.

BACKGROUND: Given the concerns regarding the adverse health outcomes associated with weight gain and metabolic syndrome in relation to use of second-generation antipsychotics (SGAs), we aimed in this study to explore whether the increase in the use of SGAs would have any impacts on the trend of excess mortality in people with schizophrenia and bipolar disorder (BPD). METHOD: Two nationwide samples of individuals with schizophrenia and BPD were identified in Taiwan's National Health Insurance Research Database in 2003 and in 2008, respectively. Age- and gender-standardized mortality ratios (SMRs) were calculated for each of the 3-year observation periods. The SMRs were compared between the calendar year cohorts, by disease group, and by causes of death. RESULTS: The mortality gap for people with schizophrenia decreased slightly, revealing an SMR of 3.40 (95% CI 3.30-3.50) for the 2003 cohort and 3.14 (3.06-3.23) for the 2008 cohort. The mortality gap for BPD individuals remained relatively stable with only those aged 15-44 years having an SMR rising significantly from 7.04 (6.38-7.76) to 9.10 (8.44-9.79). Additionally, in this group of BPD patients aged 15-44 years, the natural-cause-SMR increased from 5.65 (4.93-6.44) to 7.16 (6.46-7.91). CONCLUSIONS: Compared with the general population, the gap in the excess mortality for people with schizophrenia reduced slightly. However, the over 200% difference between the cohorts in the excess mortality for BPD individuals aged 15-44 years could be a warning sign. Future research to further examine the related factors underlying those changes is warranted.

B lymphocyte-induced maturation protein 1 (BLIMP-1) attenuates autoimmune diabetes in NOD mice by suppressing Th1 and Th17 cells.

AIMS/HYPOTHESIS: Recent reports indicate that B lymphocyte-induced maturation protein 1 (BLIMP-1), encoded by the Prdm1 gene, expands its control over T cells and is associated with susceptibility to colitis in mice with T cell-specific BLIMP-1 deficiency. In this study, we aimed to investigate the potential role of BLIMP-1 in regulating autoimmune diabetes and T helper type 17 (Th17) cells. METHODS: We generated T cell-specific Blimp1 (also known as Prdm1) transgenic (Tg) or conditional knockout (CKO) NOD mice, in which Blimp1 is overexpressed or deleted in T cells, respectively. By side-by-side analysing these Tg or CKO mice, we further dissected the potential mechanisms of BLIMP-1-mediated modulation on autoimmune diabetes. RESULTS: Overproduction of BLIMP-1 in T cells significantly attenuated insulitis and the incidence of diabetes in NOD mice. Consistent with these results, the diabetogenic effect of splenocytes was remarkably impaired in Blimp1 Tg mice. Moreover, overproduction of BLIMP-1 repressed the proliferation and activation of lymphocytes and enhanced the function of regulatory T cells (Tregs) in NOD mice. In contrast, mice lacking BLIMP-1 in T cells markedly increased Th1 and Th17 cells, and developed highly proliferative and activated lymphocytes. Strikingly, overexpansion of Th1 and Th17 cells in CKO mice was significantly reduced by introducing a Blimp1 transgene, reinforcing the emerging role of BLIMP-1 in autoimmunity. CONCLUSIONS/INTERPRETATION: We conclude that BLIMP-1 orchestrates a T cell-specific modulation of autoimmunity by affecting lymphocyte proliferation and activation, Th1 and Th17 cell differentiation, and Treg function. Our results provide a theoretical basis for developing BLIMP-1-manipulated therapies for autoimmune diabetes.

Plasma glucose-lowering action of allantoin is induced by activation of imidazoline I-2 receptors in streptozotocin-induced diabetic rats.

Allantoin, an active principle of yam, is documented to lower plasma glucose in diabetic rats. However, action mechanisms of allantoin remain obscure. It has been indicated that metformin shows ability to activate imidazoline I-2 receptors (I-2R) to lower blood sugar. Allantoin has also a chemical structure similar to metformin; both belong to guanidinium derivative. Thus, it is of special interest to know the effect of allantoin on I-2R. In the present study, the marked plasma glucose-lowering action of allantoin in streptozotocin-induced type-1 like diabetic rats was blocked by specific I-2R antagonist, BU224, in a dose-dependent manner. Also, the increase of ß-endorphin release by allantoin was blocked by BU224 in the same manner. Otherwise, amiloride at the dose sufficient to block I-2AR abolished the allantoin-induced ß-endorphin release and inhibited the blood glucose-lowering action of allantoin markedly but not completely. The direct effect of allantoin on glucose uptake in isolated skeletal muscle was also blocked by BU224. Also, the phosphorylation of AMPK in isolated skeletal muscle was raised by allantoin in a concentration-dependent manner. More-over, insulin sensitivity in diabetic rats was markedly increased by allantoin and this action was also blocked by BU224. These results suggest that allantoin has an ability to activate imidazoline I-2R while I-2AR is linked to the increase of ß-endorphin release and I-2BR is related to other actions including the influence in skeletal muscle for lowering of blood glucose in type-1 like diabetic rats. Thus, allantoin can be developed to treat diabetic disorders in the future.

Activation of imidazoline I-2B receptors by allantoin to increase glucose uptake into C2C12 cells.

Allantoin, an active principle of the yam, belongs to the group of guanidinium derivatives and has been reported to lower plasma glucose in diabetic animals. Recent evidence indicates that activation of the imidazoline I(2B) receptor (I(2B)R) by guanidinium derivatives also increases glucose uptake; however, the effect of allantoin on I(2B)R is still unknown. Glucose uptake into cultured C2C12 cells was determined using 2-[¹4C]-deoxy-D-glucose as a tracer. The changes in 5'-AMP-activated protein kinase (AMPK) expression were also identified by Western blotting analysis. The allantoin-induced glucose uptake action was dose-dependently blocked by BU224, a specific I2R antagonist, in C2C12 cells. Moreover, AMPK phosphorylation by allantoin was found to be dose-dependently increased in C2C12 cells using AICAR treatment as a reference. In addition, both actions of allantoin, the increases in glucose uptake and AMPK phosphorylation, were dose-dependently attenuated by amiloride in C2C12 cells. Moreover, compound C at concentrations sufficient to inhibit AMPK blocked the allantoin-induced glucose uptake and AMPK phosphorylation. Thus, we suggest that allantoin can activate I(2B)R to increase glucose uptake into cells, and propose I(2B)R as a new target for diabetic therapy.

Impaired skin wound healing in lumican-null mice.

BACKGROUND: Previous studies have demonstrated that the lack of lumican delayed corneal wound healing in lumican-null (Lum(-/-) ) mice. This defect is rescued by the addition of glycosylated lumican core protein to the injured corneas. OBJECTIVES: We examined the hypothesis that lumican is also required for the healing of cutaneous wounds using Lum(-/-) mice. METHODS: We demonstrated the basic thinner skin phenotypes in Lum(-/-) mice at different time points and the changes in arrangement of collagen fibres by transmission electron microscopy (TEM). A full skin thickness wound was generated by punch biopsy (6 mm diameter) in experimental Lum(-/-) and wild-type mice. The closure of injured skin was measured after various periods of time (3, 6, 12, 18 days). Specimens of injured and uninjured skin (serving as control) were then subjected to morphological examination with haematoxylin and eosin and Masson trichrome stains, and by TEM. Immunohistochemical staining with anti-CD68 antibody was used to assess the presence of macrophages in injured skin healing for various periods of time. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to elucidate the transforming growth factor (TGF)-ß1-induced myofibroblast phenotypic genes. RESULTS: Skin of adult Lum(-/-) mice (3 months and older) was much thinner (40% less) than that of age-matched wild-type mice. This phenomenon was aggravated in older mice. TEM revealed disoriented and irregular collagen fibrils in the dermis of Lum(-/-) mice. Delayed wound healing with an increase in inflammatory macrophages was compatible with the delayed response of the expression of TGF-ß1, type I collagen α1 and fibronectin at the mRNA level by semiquantitative RT-PCR in the Lum(-/-) mice. CONCLUSIONS: Our data demonstrate that lumican plays pivotal roles in skin collagen fibrillogenesis and wound healing.

Umbilical separation time delayed by alcohol application.

AIMS: To compare the effects on time of umbilical cord separation of cleaning with 95% alcohol and natural drying in a high-humidity subtropical country. METHODS: One hundred and fifty neonates were randomly assigned to two groups, 75 in each. For the control group, umbilical cleansing with 95% alcohol was performed after daily bathing; natural drying without a topical regimen was used for the trial group. RESULTS: Complete information was obtained for 71 neonates in the control group and 71 in the trial group. At 1 month after delivery, no enrolled neonate had developed omphalitis or skin infection. Cord separation time was significantly reduced for the natural-drying group compared with the alcohol-cleansing group (p=0.014). In both groups, separation time was longer for newborns delivered by caesarean section than for those delivered vaginally (p=0.001). Nine mothers in the trial group and five in the control group complained of discharge from the umbilicus. Separation time was not influenced by gender, gestational age, birthweight or length, gravidity, meconium staining, maternal age or presence of discharge. CONCLUSIONS: Cleaning with 95% alcohol did not reduce umbilical cord separation time. This traditional method is not necessary for routine cord management, even in a subtropical country.

Late toxicities in concurrent chemoradiotherapy using high-dose-rate intracavitary brachytherapy plus weekly cisplatin for locally advanced cervical cancer: a historical cohort comparison against two previous different treatment schemes.

PURPOSE: To determine the long-term toxicity of concurrent chemoradiotherapy (CCRT), using high-dose rate intracavitary brachytherapy (HDRICB) compared to radiation (RT) alone in patients with advanced cervical cancer using a control-cohort study. METHODS: A total of 332 cases of Stage IIB-III disease were included in this comparative study. Seventy-three patients were treated with a 3-insertion schedule and labeled group A, whereas the other 146 patients with a 4-insertion schedule became group B. One hundred and thirteen patients treated by a 4-insertion protocol with concurrent weekly cisplatin were labeled group C. RESULTS: The cumulative rate of grade 2 or above rectal complication was 13.7% for group A, 9.6% for the group B and 15.9% for group C (p = 0.76), whereas the grade 3 to 4 non-rectal radiation-induced intestinal injury was 6.8% for group A, 6.2% for group B and 9.7% for group C (p = 0.20). Grade 2 to 4 late bladder toxicity was higher in group C, with the cumulative rate being 5.5% for group A, 4.8% for group B and 15.0% for group C (p = 0.004). The independent factor for a rectal complication was the occurrence of a bladder complication (p = 0.01, hazard ratio 3.06). The independent factors for bladder complications were the use of CCRT (p = 0.01, hazard ratio 2.08), and the occurrence of rectal complications (p = 0.02, hazard ratio 2.77). CONCLUSIONS: When treating advanced cervical cancer, HDRICB consisting of four 6 Gy insertions and weekly cisplatin shows a trend of increasing late bladder complications. The interval between drug administration and HDRICB should be kept long enough to avoid any synergistic effect of both regimens.

Bifurcation of cell migratory and proliferative signaling by the adaptor protein Shc.

Cytokines and extracellular matrix proteins initiate signaling cascades that regulate cell migration and proliferation. Evidence is provided that the adaptor protein Shc can differentially regulate these processes. Specifically, under growth factor-limiting conditions, Shc stimulates haptotactic cell migration without affecting anchorage-dependent proliferation. However, when growth factors are present, Shc no longer influences cell migration; rather, Shc is crucial for DNA synthesis. Mutational analysis of Shc demonstrates that, while tyrosine phosphorylation is required for both DNA synthesis and cell migration, the switch in Shc signaling is associated with differential use of Shc's phosphotyrosine interacting domains; the PTB domain regulates haptotaxis, while the SH2 domain is selectively required for proliferation.

Molecular mimicry by herpes simplex virus-type 1: autoimmune disease after viral infection.

Viral infection is sometimes associated with the initiation or exacerbation of autoimmune disease, although the underlying mechanisms remain unclear. One proposed mechanism is that viral determinants that mimic host antigens trigger self-reactive T cell clones to destroy host tissue. An epitope expressed by a coat protein of herpes simplex virus-type 1 (HSV-1) KOS strain has now been shown to be recognized by autoreactive T cells that target corneal antigens in a murine model of autoimmune herpes stromal keratitis. Mutant HSV-1 viruses that lacked this epitope did not induce autoimmune disease. Thus, expression of molecular mimics can influence the development of autoimmune disease after viral infection.

Development of amoxicillin enzyme-linked immunosorbent assay and measurements of tissue amoxicillin concentrations in a pigeon microdialysis model.

A sensitive ELISA was developed for the detection of amoxicillin (AMX) in serum, urine, and milk. The ELISA used an indirect competitive method produced by coating the plate with ovalbumin conjugated with AMX hapten. Antibodies against AMX-BSA were detected by a goat-antirabbit antibody conjugated with peroxidase. Calibration standard curves ranged from 1.28 ng/mL to 20 microg/mL [IC(50) (inhibition concentration 50%) = 100 ng/mL], and the limits of detection were 1.3, 2.7, and 4.8 ng/mL for urine, milk, and serum, respectively. The intra- and interassay variations were less than 4 and 9.6%. The antibody produced against AMX cross-reacted highly with penicillin G (77%); cross-reacted moderately with ampicillin, oxacillin, and cloxacillin (56.9, 51.4, and 48.8%, respectively); but was considered non-cross-reactive with dicloxacillin (7.4%), cefadroxil (<1%), and cefazolin (<1%). Concentrations of AMX were measured simultaneously in venous blood and muscles by using the developed AMX ELISA in an in vivo microdialysis model designed for pigeons. Following i.m. injection (25 mg/kg), AMX attained a peak blood level of 4.74 +/-0.30 mu g/mL and decreased with a half-life of 2.38 +/-0.16 h. In contrast, measurements in pectoral and femoral muscles exhibited delayed appearances, reduced peak concentrations, and prolonged half-lives of 4.07 +/-0.48 (pectoral) and 3.01 +/-0.26 (femoral) that were significantly different from each other and those in the blood (P < 0.05). Blood protein binding was calculated to be 27.9 +/-5.7%. This study demonstrated the semiquantitative application of a selective AMX ELISA in the first microdialysis procedure for continuous monitoring of drug levels in specific tissues of pigeons and maybe useful for related studies in other poultry species.

Point-of-care sensors for the management of sepsis.

Point-of-care sensors that enable the fast collection of information relevant to a patient's health state can facilitate improved health access, reduce healthcare costs and improve the quality of healthcare delivery. In the diagnosis of sepsis - defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection, and the leading cause of in-patient death and of hospital readmission in the United States - predicting which infections will lead to life-threatening organ dysfunction and developing specific anti-sepsis treatments remain challenging because of the significant heterogeneity of the host response. Yet the use of point-of-care devices could reduce the time from the onset of a patient's infection to the administration of appropriate therapeutics. In this Perspective, we describe the current state of point-of-care sensors for the diagnosis and monitoring of sepsis, and outline opportunities in the use of these devices to dramatically improve patient care.

Polygenic risk for schizophrenia and neurocognitive performance in patients with schizophrenia.

Both neurocognitive deficits and schizophrenia are highly heritable. Genetic overlap between neurocognitive deficits and schizophrenia has been observed in both the general population and in the clinical samples. This study aimed to examine if the polygenic architecture of susceptibility to schizophrenia modified neurocognitive performance in schizophrenia patients. Schizophrenia polygenic risk scores (PRSs) were first derived from the Psychiatric Genomics Consortium (PGC) on schizophrenia, and then the scores were calculated in our independent sample of 1130 schizophrenia trios, who had PsychChip data and were part of the Schizophrenia Families from Taiwan project. Pseudocontrols generated from the nontransmitted parental alleles of the parents in these trios were compared with alleles in schizophrenia patients in assessing the replicability of PGC-derived susceptibility variants. Schizophrenia PRS at the P-value threshold (PT) of 0.1 explained 0.2% in the variance of disease status in this Han-Taiwanese samples, and the score itself had a P-value 0.05 for the association test with the disorder. Each patient underwent neurocognitive evaluation on sustained attention using the continuous performance test and executive function using the Wisconsin Card Sorting Test. We applied a structural equation model to construct the neurocognitive latent variable estimated from multiple measured indices in these 2 tests, and then tested the association between the PRS and the neurocognitive latent variable. Higher schizophrenia PRS generated at the PT of 0.1 was significantly associated with poorer neurocognitive performance with explained variance 0.5%. Our findings indicated that schizophrenia susceptibility variants modify the neurocognitive performance in schizophrenia patients.

Comparison of a new modified laparoscopic presacral neurectomy and conventional laparoscopic presacral neurectomy in the treatment of midline dysmenorrhea.

OBJECTIVE: To describe a newly modified laparoscopic presacral neurectomy procedure and to evaluate the long-term benefits of the surgery as a treatment for midline dysmenorrhea. METHOD: Eighty-eight reproductive female patients with midline dysmenorrhea were enrolled in the non-randomized prospective study. There were fifty-five patients in the modified laparoscopic presacral neurectomy (MLPSN) group and thirty-three patients in the conventional laparoscopic presacral neurectomy (LPSN) group. All patients received post-surgery follow-up of more than eight years for evaluation with respect to pain relief, recurrence, and complications. RESULTS: Upon receipt of surgery, the MLPSN and the LPSN groups both demonstrated a significant decrease (P<0.001) in the mean pain score when compared to the pre-surgery mean pain scores. However, the probability of recurrence during the eight years of follow-up was 81.8% (27 patients) in the LPSN group, compared to 43.6% (24 patients) in the MLPSN group, resulting in a significantly lower long-term recurrence rate in the MLPSN group, compared to the LPSN group (P<0.05). No patients in the MLPSN group had long-term complications and one patient had constipation after surgery in the LPSN group. CONCLUSION: The modified laparoscopic presacral neurectomy procedure provides an alternative for those patients who suffer intractable midline dysmenorrhea. This surgery is relatively simple and safe and could result in a satisfactory long-term outcome in the intervention of midline dysmenorrhea.

Protein Information Resource: a community resource for expert annotation of protein data.

The Protein Information Resource, in collaboration with the Munich Information Center for Protein Sequences (MIPS) and the Japan International Protein Information Database (JIPID), produces the most comprehensive and expertly annotated protein sequence database in the public domain, the PIR-International Protein Sequence Database. To provide timely and high quality annotation and promote database interoperability, the PIR-International employs rule-based and classification-driven procedures based on controlled vocabulary and standard nomenclature and includes status tags to distinguish experimentally determined from predicted protein features. The database contains about 200,000 non-redundant protein sequences, which are classified into families and superfamilies and their domains and motifs identified. Entries are extensively cross-referenced to other sequence, classification, genome, structure and activity databases. The PIR web site features search engines that use sequence similarity and database annotation to facilitate the analysis and functional identification of proteins. The PIR-Inter-national databases and search tools are accessible on the PIR web site at http://pir.georgetown.edu/ and at the MIPS web site at http://www.mips.biochem.mpg.de. The PIR-International Protein Sequence Database and other files are also available by FTP.

Factors Determining Physical and Mental Quality of Life of Living Kidney Donors in Taiwan.

BACKGROUND: Living-donor kidney transplantation has a positive influence on recipients' life expectancy and improves quality of life for patients with end-stage renal disease compared with dialysis patients. Evaluation of the physical and mental quality of life for donors can promote positive perceptions about donation and help potential donors in their decision-making process. The aim of this study was to explore the predictive factors of quality of life for living kidney donors. METHODS: A cross-sectional and descriptive design was used, and the study was conducted from January to July 2013. The donors were a convenience sample of 34 participants who had undergone kidney transplant surgery >1 year earlier. RESULTS: The results showed that kidney donors had a low to moderate physical and mental quality of life. Multiple regression analysis revealed that financial concerns and anxiety explained 27.8% of the total variance of quality of life in the physical component. Anxiety and paid work explained 61.4% of the total variance of quality of life in the mental component. CONCLUSIONS: After renal transplantation, living kidney donors experienced low to moderate quality of life. Because donors are family members (siblings, sons or daughters, spouses, or parents), monthly family income is a significant issue that influences both the decision to donate and quality of life after transplantation. Our findings suggest that pre-transplantation assessment must include social workers as part of the health care team to evaluate the impact of a donor's financial status on post-transplantation quality of life.

An improved preparation of phosphatidylglycerophosphate.

Phosphatidylglycerophosphate is not normally accumulated in the reaction mixture. It was found that octyl-beta-D-glucopyranoside greatly stimulated the synthesis and inhibited the degradation of phosphatidylglycerophosphate. The phenomenon could be used for the preparation of phosphatidylglycerophosphate from CDPdiacylglycerol and the sn-glycero-3-phosphate with the crude membrane enzyme preparation. The optimal concentration of octyl-beta-D-glucopyranoside to be used for such a purpose was 24.5 mM.

A second-site mutation at glutamate-257 that restores the function of the mutant yeast ribosomal protein L5 containing lysine-270,271-->arginine.

A genetic approach was used to identify interacting regions of yeast ribosomal protein L5 (also known as L1, L1a, or YL3). Previous studies from our laboratory showed that residues K270 and K271 in protein L5 are essential for its function. The mutant L5 protein in which both residues were replaced by arginine residues (K270,271R) exhibited about 80% RNA binding capability compared to the wild-type and the mutant protein was assembled into the 60S ribosomal subunits in vivo. The yeast strain expressing this mutant protein in a homozygous form was lethal (Biochim. Biophys. Acta 1308 (1996) 133-141). In the present study, this non-functional mutant was used to select intragenic suppressors. A spontaneous, intragenic suppressor which contained an E257K substitution (in addition to the primary mutations) was identified. The suppressor protein bound about 60% of yeast 5S rRNA in vitro compared to the wild-type. To gain more insight into the nature of the intragenic suppressor, additional mutant proteins in which E257 was substituted by a variety of amino acids were produced by site-directed mutagenesis. The ability of each mutant protein to bind yeast 5S rRNA in vitro and to suppress the lethal effect of the double K270,271 mutation in vivo were examined. Results suggest communication between two non-contiguous domains on protein L5 and that several factors, such as electrostatic interaction and hydrogen bonding are likely to play a role in this global communication. Mutation studies on E257 alone also reveal that substitutions of this residue in L5 protein could affect cell growth under specified conditions, but a variety of changes could be tolerated without serious deleterious effects. We propose a working model in which E257 is located in a loop and the dynamic as well as the flexibility of this loop is important for L5 function.