Effect of thallium on the growth of Anacystis nidulans and Chlamydomonas reinhardtii.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
L H Lee
Publications and source records attributed to L H Lee.
Characterization of avian reovirus non structural protein sigmaNS synthesized in Escherichia coli.
The coding region of avian reovirus S1133 genomic segment S4, encoding the non structural protein sigmaNS, was inserted into expression vector pET28a and the protein was expressed in Escherichia coli BL21(DE3) as a fusion protein containing a C-terminal peptide with six tandem histidines (His-tag). The expressed protein (esigmaNS) consistent with the expected molecular size of the avian reovirus protein sigmaNS synthesized in infected cells was readily purified by His-Bind Resin. The esigmaNS was further confirmed to be indistinguishable from viral sigmaNS by immunoblot analysis. The esigmaNS binds 32P-labeled ssRNA probe produced by run-off transcription of clone pGEM-3Zf(+)S4. The binding activity is blocked by heterologous yeast rRNA, but not by homologous avian reovirus dsRNA and heterologous infectious bursal disease virus dsRNA and salmon sperm dsDNA. Therefore, the ssRNA-binding activity of the expressed protein sigmaNS is non sequence-specific, similar to that previously described for viral sigmaNS purified from avian reovirus infected cell extracts. In addition, the recent data also show that the optimal salt (NaCl) concentration and pH for its binding are 100-150 mM and 7.0, respectively, in terms of the UV cross-linking and RNase A treatment of the reaction mixtures prior to the denaturing gel analysis.
Animals↗
Experimental infections of rabbits with rabbit haemorrhagic disease virus monitored by polymerase chain reaction.
Adult and 4-5-week-old rabbits were inoculated subcutaneously with rabbit haemorrhagic disease virus (RHDV). Samples were prepared from various tissues at intervals postinoculation (PI) for the detection of viral RNA and antigens. Using a haemagglutination test (HAT), viral antigens were detected in the liver, bile and spleen of the adult rabbits at and after 36 h PI. The reverse transcription-polymerase chain reaction (RT - PCR) showed that RHDVRNA was present in the liver, bile and spleen as early as 18 hours PI, whereas lung, kidney, thymus, mesenteric lymph node and buffy coat were found to be positive after more than 26 hours PI. In addition, viral RNA in urine and faeces showed a variable positivity at and after 36 hours PI. In the young rabbits, RT - PCR showed that RHDVRNA was present as early as 1 day PI in the liver, bile, spleen and buffy coat; whereas lung, kidney, thymus, mesenteric lymph node and faeces were found to be positive at and after 2 days PI. Bile and spleen were the only samples in which viral RNA was detected throughout the length of the experiment. Virus was not reactivated in six recovered virus-inoculated rabbits treated with dexamethasone or a classical swine fever virus vaccine. Using a haemagglutination inhibition test and an ELISA, antibody titres increased rapidly from one week PI onwards, peaked at approximately three weeks of age, and were maintained throughout the length of the experiment.
Aging↗
An enzyme-linked immunosorbent assay for the detection of antibody to avian reovirus by using protein sigma B as the coating antigen.
An enzyme-linked immunosorbent assay using the expressed protein sigma B as the coating antigen (sigma B-ELISA) for detecting antibody to avian reovirus (ARV) in chickens was developed and compared with a conventional ELISA. Both ELISA s and a serum neutralisation (SN) test were used to test the sera from experimentally vaccinated and farm chickens. The sigma B-ELISA could clearly distinguish the SN-positive and -negative sera in 38-week-old chickens. The correlation rate between SN and a sigma B-ELISA was 100 per cent (65/65), and that between SN and conventional ELISA was 84 per cent (55/65). With the sigma B-ELISA, all SN-negative sera had low absorbance values (below 0.06), and the absorbance values correlated closely with the SN titres. However, the sera which were antibody-negative by SN had various absorbance values, ranging from 0.07 to 0.39 in the conventional ELISA. Hence, the sigma B-ELISA had lower non-specific binding reactions than the conventional ELISA against sera from ARV -negative birds. Antibody against ARV could be detected by sigma B-ELISA after vaccination. Absorbance values peaked 4 weeks after vaccination at 2 weeks of age and were maintained until the birds were 27 weeks old. The results suggest that the presence of antibody against viral protein sigma B in birds may be used as a good indicator by the sigma B - ELISA for detecting immune status of a chicken flock or to detect chickens infected with ARV.
Animals↗
Cytoplasmic sequestration of rel proteins by IkappaBalpha requires CRM1-dependent nuclear export.
Rel and IkappaB protein families form a complex cellular regulatory network. A major regulatory function of IkappaB proteins is to retain Rel proteins in the cell cytoplasm. In addition, IkappaB proteins have also been postulated to serve nuclear functions. These include the maintenance of inducible NF-kappaB-dependent gene transcription, as well as termination of inducible transcription. We show that IkappaBalpha shuttles between the nucleus and the cytoplasm, utilizing the nuclear export receptor CRM1. A CRM1-binding export sequence was identified in the N-terminal domain of IkappaBalpha but not in that of IkappaBbeta or IkappaBepsilon. By reconstituting major aspects of NF-kappaB-IkappaB sequestration in yeast, we demonstrate that cytoplasmic retention of p65 (also called RelA) by IkappaBalpha requires Crm1p-dependent nuclear export. In mammalian cells, inhibition of CRM1 by leptomycin B resulted in nuclear localization of cotransfected p65 and IkappaBalpha in COS cells and enhanced nuclear relocation of endogenous p65 in T cells. These observations suggest that the main function of IkappaBalpha is that of a nuclear export chaperone rather than a cytoplasmic tether. We propose that the nucleus is the major site of p65-IkappaBalpha association, from where these complexes must be exported in order to create the cytoplasmic pool.
Animals↗
Tubular adenomas of the breast: imaging findings with histologic correlation.
OBJECTIVE: The purpose of this study is to describe the imaging features of tubular adenomas, which are rare benign breast tumors usually found in women younger than 35 years old. CONCLUSION: In young women, tubular adenomas can look like noncalcified fibroadenomas on mammography and sonography. In older women, tubular adenomas may resemble malignant masses with microcalcifications. Awareness of these findings may help in assessing concordance between imaging and histologic findings after percutaneous core biopsy of these rare lesions.
Adenoma↗
Thrombotic and haemorrhagic complications in patients with mechanical heart valve prostheses attending the Singapore General Hospital Anticoagulation Clinic.
INTRODUCTION: This study evaluated the intensity of anticoagulation required for prevention of thromboembolic episodes with minimal haemorrhagic complications in patients with mechanical heart valve prostheses. MATERIALS AND METHODS: The incidence of thrombotic and haemorrhagic events was retrospectively assessed in a series of 143 patients attending the anticoagulation clinic over a period of 67 months. Risk factors for haemostatic events were also analysed. RESULTS: All embolic events occurred when the International Normalised Ratio (INR) was less than 2.2, suggesting an INR of 2.5 to 3.0 should be adequate for thromboembolic prophylaxis. Risk factors for embolic events were atrial fibrillation, mitral valve prosthesis and a previous thromboembolic event. Most embolic events involved the central nervous system with resultant permanent residual disability. Most major bleeding episodes occurred in the presence of underlying pathological states such as peptic ulcers or fibroids and were not related to the intensities of anticoagulation. There was no mortality or long-term morbidity associated with bleeding episodes. CONCLUSIONS: In agreement with recent data from other centres, a moderate intensity of anticoagulation of INR 2.5 to 3.0 is now recommended. Hence, with this lowered intensity of anticoagulation and better patient education, we hope that thrombotic as well as haemorrhagic complications will be reduced in future.
Adolescent↗
Susceptibility of piglets to rabbit hemorrhagic disease virus following experimental infection.
The possibility exists that rabbit hemorrhagic disease virus (RHDV) can be transmitted to swine, through lapinized hog cholera virus (HCV) vaccine. To investigate the infectivity of RHDV in swine, 16 four- to six-week-old piglets were inoculated subcutaneously with RHDV, and samples of liver, lung, spleen, kidney, bile, adrenal gland, tonsil, mesenteric lymph node, thymus, urine, buffy coat, and feces were collected from each of 2 animals on Days 0, 1, 2, 3, 5, 7, 14, and 28 post infection. Using reverse transcription-polymerase chain reaction, viral RNA was detected in most tissues by Day 3 and was absent after Day 5, except in lung and liver tissues, in which viral RNA was detected up to Day 14. Viral RNA was not detected in kidney, urine, feces or bile. Antibody responses, as detected by hemagglutination inhibition, were of low titer and short duration, and were similar in animals inoculated with viable RHD and in those given formalin-inactivated RHDV (n = 2). Neither viral RNA nor antibody were detected in the negative control or in the uninfected, in-contact animals.
Animals↗
Effect of selenium on the growth of the cyanobacterium Anacystis nidulans.
Explore the source record for details and available documents.
Cell Division↗
Evaluation of a truncated recombinant flagellin subunit vaccine against Campylobacter jejuni.
A recombinant protein comprising the maltose-binding protein (MBP) of Escherichia coli fused to amino acids 5 to 337 of the FlaA flagellin of Campylobacter coli VC167 was evaluated for immunogenicity and protective efficacy against challenge by a heterologous strain of campylobacter, Campylobacter jejuni 81-176, in two murine models. The sequence of the flaA gene of strain 81-176 revealed a predicted protein which was 98.1% similar to that of VC167 FlaA over the region expressed in the fusion protein. Mice were immunized intranasally with two doses of 3 to 50 microgram of MBP-FlaA, given 8 days apart, with or without 5 microgram of the mutant E. coli heat-labile enterotoxin (LT(R192G)) as a mucosal adjuvant. The full range of MBP-FlaA doses were effective in eliciting antigen-specific serum immunoglobulin G (IgG) responses, and these responses were enhanced by adjuvant use, except in the highest dosing group. Stimulation of FlaA-specific intestinal secretory IgA (sIgA) responses required immunization with higher doses of MBP-FlaA (>/=25 microgram) or coadministration of lower doses with the adjuvant. When vaccinated mice were challenged intranasally 26 days after immunization, the best protection was seen in animals given 50 microgram of MBP-FlaA plus LT(R192G). The protective efficacies of this dose against disease symptoms and intestinal colonization were 81.1 and 84%, respectively. When mice which had been immunized with 50 microgram of MBP-FlaA plus LT(R192G) intranasally were challenged orally with 8 x 10(10), 8 x 10(9), or 8 x 10(8) cells of strain 81-176, the protective efficacies against intestinal colonization at 7 days postinfection were 71.4, 71.4, and 100%, respectively.
Amino Acid Sequence↗
Activated protein C resistance: a study among 60 thromboembolic patients in the Singapore population.
Resistance to activated protein C (APC-R) is the commonest inherited cause of thrombosis among Caucasians. Few studies have been carried out on its prevalence in Asians. We conducted a prospective study on 60 patients with thromboembolism to determine its prevalence in our local population. The Factor V Leiden (VaQ506) mutation associated with this condition was detected by amplification of the Factor V gene by polymerase chain reaction (PCR) and digestion of the fragment with Mnl I. Three patients were found to be heterozygous for this mutation. None of the 3 patients had other concomitant hypercoagulable states. In addition, we studied the prevalence of this condition in Malays which was found to be 0.5%. Our study suggests that the incidence of APC-R is much lower here compared to the West.
Activated Protein C Resistance↗
Crm1p mediates regulated nuclear export of a yeast AP-1-like transcription factor.
The yeast AP-1-like transcription factor, Yap1p, activates genes required for the response to oxidative stress. Yap1p is normally cytoplasmic and inactive, but will activate by nuclear translocation if cells are placed in an oxidative environment. Here we show that Yap1p is a target of the beta-karyopherin-like nuclear exporter, Crm1p. Yap1p is constitutively nuclear in a crm1 mutant, and Crm1p binds to a nuclear export sequence (NES)-like sequence in Yap1p in the presence of RanGTP. Recognition of Yap1p by Crm1p is inhibited by oxidation, and this inhibition requires at least one of the three cysteine residues flanking the NES. These results suggest that Yap1p localization is largely regulated at the level of nuclear export, and that the oxidation state affects the accessibility of the Yap1p NES to Crm1p directly. We also show that a mutation in RanGAP (rna1-1) is synthetically lethal with crm1 mutants. Yap1p export is inhibited in both rna1-1 and prp20 (RanGNRF) mutant strains, but Yap1p rapidly accumulates at the nuclear periphery after shifting rna1-1, but not other mutant cells to the non-permissive temperature. Thus, disassembly of export complexes in response to RanGTP hydrolysis may be required for release of substrate from a terminal binding site at the nuclear pore complex (NPC).
Amino Acid Sequence↗
Characterization of rabbit hemorrhagic disease virus field isolates in Taiwan.
Liver tissues from animals that were suspected to have died of rabbit hemorrhagic disease (RHD) were used for isolation and characterization of the causative agent. Three strains of RHD virus were isolated as the supernatants of liver homogenates reacted positively by hemagglutination (HA) assays and were infective for rabbits after second passage in animals. Following extraction of liver homogenates from animals infected with each of three isolates, each virus strain was purified by CsCl density gradient ultracentrifugation for further characterization. In negative-stained preparations, the purified virions were icosahedral, measured approximately 40 nm in diameter, and were without an envelope. Morphologically, the three isolates were identical. By immunoblotting, a protein with a molecular weight of 60,000 was identified as the major structural protein in each isolate. Furthermore, two sets of primer framed two different regions within RHD virus genome and could amplify two fragments of the expected size, respectively, from each isolate, whereas, none were obtained from uninfected control samples. The identity of the amplified products was confirmed further using different restriction endonucleases. Among three isolates of RHD virus, neither protein migration patterns of the virions nor cleavage patterns of the amplified product by restriction enzymes were found to differ.
Animals↗
Congenital tuberculosis in a neonatal intensive care unit: case report, epidemiological investigation, and management of exposures.
Disseminated tuberculosis was diagnosed at the autopsy of a 65-day-old premature infant who died in a 52-bed neonatal intensive care unit (NICU). Both parents and one sibling had previously had positive tuberculin skin tests (TSTs); none had active pulmonary tuberculosis, but a second sibling had hilar adenopathy. Congenital transmission was confirmed by isolation of Mycobacterium tuberculosis from the mother's endometrium and the infant's lung tissue. Both strains were identical by DNA restriction fragment analysis. TSTs were performed on 14 neonates, 27 NICU visitors, 11 contacts of the family, and 260 health care workers. TST conversion occurred in two nurses (0.8%); both had normal chest radiographs and received isoniazid therapy. Exposed neonates had negative chest radiographs, had negative gastric aspirates for acid-fast bacilli, and received isoniazid preventive therapy. Diagnosis of congenital tuberculosis requires a high index of suspicion. Transmission of tuberculosis in the NICU setting is unusual but can occur.
Cross Infection↗
Identification and characterization of RNA-binding activities of avian reovirus non-structural protein sigmaNS.
Cytoplasmic extracts prepared from avian reovirus (ARV) strain S1133-infected chicken embryo fibroblasts were examined for the presence of RNA-binding proteins in order to identify and characterize ARV RNA-binding proteins. Analysis of binding activity to poly(A)-Sepharose indicated that infected cells contained significant amounts of a protein that co-migrated with ARV protein sigmaNS present in total virus-infected cell extracts. Determination of the N-terminal amino acid sequence of several peptide fragments generated by V8 protease digestion of the poly(A)-Sepharose-purified protein confirmed that this viral protein was sigmaNS. Competition assays showed that single-stranded RNA from the unrelated avian pathogen infectious bursal disease virus was able to compete for binding of sigmaNS to poly(A)-Sepharose. These data suggest that ARV sigmaNS binds to single-stranded RNA in a nucleotide sequence non-specific manner and is functionally similar to its counterpart specified by mammalian reovirus.
Animals↗
A study of idiopathic thrombocytopenic purpura (ITP) patients over a ten-year period.
Adult idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder caused by antiplatelet autoantibodies that cause platelet destruction by the reticuloendothelial system. The disease has been well-documented in the West. We studied 78 ITP patients diagnosed and followed up in a tertiary hospital, over a 10-year period, to give a profile of our local patients and their response to treatment. The majority of patients were females and fall in the 20 to 39 years age group. 21.8% were asymptomatic at presentation. The mean presenting platelet count was 31 x 10(9)/L. Complete response rate to steroid treatment was 46.7%. Thirty-seven patients (47.4%) underwent splenectomy with a success rate of 64.9%. 6.4% required multiple drugs to maintain a stable platelet count. There was no spontaneous, long-term remission in this series. 10.3% of our patients eventually developed an autoimmune disease. ITP has a variable clinical course and treatment has to be highly individualised.
Adolescent↗
A case report of neutrophilic eccrine hidradenitis in a patient receiving chemotherapy for acute myeloid leukaemia.
Neutrophilic eccrine hidradenitis (NEH) is a neutrophilic dermatosis primarily affecting the eccrine glands and occurs in patients undergoing chemotherapy. It must be distinguished from infections, drug eruptions, leukaemia cutis or other forms of skin diseases. As it is self-limiting, establishing the diagnosis will avoid unnecessary treatment for infections or changes in drug therapy.
Acute Disease↗