Barrientosiimonas humi gen. nov., sp. nov., an actinobacterium of the family Dermacoccaceae

Three novel actinobacteria, strains 39T, 40 and 41, were isolated from soil collected from Barrientos Island in the Antarctic. The taxonomic status of these strains was determined using a polyphasic approach. Comparison of 16S rRNA gene sequences revealed that strain 39T represented a novel lineage within the family Dermacoccaceae and was most closely related to members of the genera Demetria (96.9 % 16S rRNA gene sequence similarity), Branchiibius (95.7 %), Dermacoccus (94.4–95.3 %), Calidifontibacter (94.6 %), Luteipulveratus (94.3 %), Yimella (94.2 %) and Kytococcus (93.1 %). Cells were irregular cocci and short rods. The peptidoglycan type was A4α with an l-Lys–l-Ser–d-Asp interpeptide bridge. The cell-wall sugars were galactose and glucose. The major menaquinone was MK-8(H4). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphoglycolipid, two glycolipids and one unknown phospholipid. The acyl type of the cell-wall polysaccharide was N-acetyl. The major cellular fatty acids were anteiso-C17 : 0 (41.97 %), anteiso-C17 : 1ω9c (32.16 %) and iso-C16 : 0 (7.68 %). The DNA G+C content of strain 39T was 68.4 mol%. On the basis of phylogenetic and phenotypic differences from other genera of the family Dermacoccaceae , a novel genus and species, Barrientosiimonas humi gen. nov., sp. nov., is proposed; the type strain of the type species is 39T ( = CGMCC 4.6864T  = DSM 24617T).

Asian venous thromboembolism guidelines: prevention of venous thromboembolism

Venous thromboembolism (VTE) prophylaxis is under-utilized in Asia because of the misconception that its incidence is lower in Asians as compared to the Caucasians. The available data on VTE in Asia is limited due to the lack of well-designed multicenter randomized controlled trials as well as non-standardized research designs, making data comparison difficult. Emerging data indicates that the VTE incidence is not low in Asia, and is comparable to that reported in the Western literature in some instances. There is also a trend towards increasing incidence of VTE, as demonstrated by a number of hospital-based studies in Asia. This could be attributed to lifestyle changes, ageing population, increasing awareness of VTE and wider availability of Duplex ultrasound. The risk of VTE in hospitalized patients remain the same in Asians and Caucasians, even though there may be factors that are inherent to patients in Asia that influence the slight variation in incidence. The utilization rate of VTE prophylaxis remains suboptimal in Asia. The Asian Venous Thrombosis Forum (AVTF) comprises participants from various countries such as China, Hong Kong, India, Indonesia, Korea, Malaysia, Philippines, Singapore, Taiwan, Thailand and experts from Australia and Europe. The forum evaluated the available data on VTE from the Asian region and formulated guidelines tailored to meet the needs of the region. We recommend that serious considerations are given to VTE prophylaxis especially in the at-risk group and a formal hospital policy be established to facilitate the implementation. On admission to the hospital, we recommend assessing the patients for both VTE and bleeding risk. We recommend mechanical prophylaxis for patients at increased risk of bleeding and utilizing it as an adjunctive measure in combination with pharmacological prophylaxis in patients with high risk of VTE. For patients undergoing general or gynecological surgery and with moderate risk for VTE, we recommend prophylaxis with one of the following: low dose unfractionated heparin (LDUH), low molecular weight heparin (LMWH), fondaparinux or intermittent pneumatic compression (IPC). For the same group of patients at high risk of VTE, we recommend pharmacological or combination of pharmacological and mechanical prophylaxis. For patients undergoing major orthopedic surgeries like total hip replacement, total knee replacement and proximal hip fracture surgery, we recommend using one of the following: LMWH, fondaparinux, rivaroxaban, apixaban, edoxaban, dabigatran, warfarin or aspirin with IPC. For patients admitted to the hospital with acute medical illness and has moderate risk of VTE, we recommend prophylaxis with LDUH, LMWH or Fondaparinux. For the same group at high risk of VTE, we recommend combination of pharmacological and mechanical prophylaxis.

Ministry of health clinical practice guidelines: clinical blood transfusion

The Health Sciences Authority (HSA) and the Ministry of Health (MOH) publish clinical practice guidelines on Clinical Blood Transfusion to provide doctors and patients in Singapore with evidence-based guidance for blood transfusion. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the HSA-MOH clinical practice guidelines on Clinical Blood Transfusion, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website (http://www.moh.gov.sg/mohcorp/publications.aspx?id=25700). The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

An abnormal nonhyperdiploid karyotype is a significant adverse prognostic factor for multiple myeloma in the bortezomib era

Multiple myeloma is clinically heterogeneous and risk stratification is vital for prognostication and informing treatment decisions. As bortezomib is able to overcome several high-risk features of myeloma, the validity of conventional risk-stratification and prognostication systems needs to be reevaluated. We study the survival data of 261 previously untreated myeloma patients managed at our institution, where bortezomib became available from 2004 for the treatment of relapse disease. Patient and disease characteristics, and survival data were evaluated overall, and with respect to bortezomib exposure. Overall, the international staging system (ISS), metaphase karyotyping and interphase fluorescence in situ hybridization (FISH) were discerning of survival outcomes, where the median for the entire cohort was 5.2 years. However, when stratified by bortezomib exposure, only metaphase karyotyping was still discriminating of long-term prognosis. The presence of an abnormal nonhyperdiploid karyotype overrides all other clinical and laboratory parameters in predicting for a worse outcome on multivariate analysis (median survival 2.6 years, P = 0.001), suggesting that bortezomib used at relapse is better able to overcome adverse risk related to high tumor burden (as measured by the ISS) than adverse cytogenetics on conventional karyotyping. Metaphase karyotyping provides additional prognostic information on tumor kinetics where the presence of a normal diploid karyotype in the absence of any high-risk FISH markers correlated with superior survival and could act as a surrogate for lower plasma cell proliferation.

Treatment and outcome of acquired haemophilia A with a standard conventional regimen in a cohort without associated conditions

Acquired haemophilia A (AH) is a rare bleeding disorder with significant risk of mortality. We conducted a study on the treatment and outcomes of patients with AH diagnosed between 1998 and 2004 in our institution. Fourteen patients (age range 17-89, median 64) were followed-up from between 10-64 months (average 32 months). Inhibitor levels ranged from 5 to 450 BU. Ten patients required either recombinant activated factor VIIa or prothrombin complexes for control of bleeding. All patients received a standard immunosuppressive regimen of prednisolone 1 mg kg day(-1) and oral cyclophosphamide 50-100 mg day(-1). In addition, nine patients received intravenous immunoglobulin. Complete remission (CR) was achieved in 88% (eight of nine evaluable patients) over durations ranging from 5-78 days (average 35 days). There were three mortality; from bleeding, sepsis and cerebral infarct. Two patients were lost to follow-up. There were no relapses among patients achieving CR. Conditions associated with AH were not identified at diagnosis or subsequent follow-up in all patients. This series represent one of the largest aetiologically and treatment-wise, uniformed cohort of AH patients. Despite toxicity concerns, the combination of prednisolone and cyclophosphamide remain an effective regimen and should be among the first line of treatment choices, with careful patient selection.

Deep-vein thrombosis rates after major orthopedic surgery in Asia. An epidemiological study based on postoperative screening with centrally adjudicated bilateral venography

BACKGROUND

The incidence of postsurgical venous thromboembolism is thought to be low in Asian ethnic populations.

OBJECTIVE

We studied the incidence of deep-vein thrombosis (DVT) in Asian patients undergoing major orthopedic surgery of the lower limbs.

PATIENTS/METHODS

We performed a prospective epidemiological study in 19 centers across Asia (China, Indonesia, South Korea, Malaysia, Philippines, Taiwan, and Thailand) in patients undergoing elective total hip replacement (THR), total knee replacement (TKR) or hip fracture surgery (HFS) without pharmacological thromboprophylaxis. The primary endpoint was the rate of DVT of the lower limbs documented objectively with bilateral ascending venography performed 6-10 days after surgery using a standardized technique and evaluated by a central adjudication committee unaware of local interpretation.

RESULTS

Overall, of 837 Asian patients screened for this survey, 407 (48.6%, aged 20-99 years) undergoing THR (n = 175), TKR (n = 136) or HFS (n = 96) were recruited in 19 centers. DVT was diagnosed in 121 of 295 evaluable patients [41.0%, (95% confidence interval (CI): 35.4-46.7)]. Proximal DVT was found in 30 patients [10.2% (7.0-14.2)]. Total DVT and proximal DVT rates were highest in TKR patients (58.1% and 17.1%, respectively), followed by HFS patients (42.0% and 7.2%, respectively), then THR patients (25.6% and 5.8%, respectively). DVT was more frequent in female patients aged at least 65 years. Pulmonary embolism was clinically suspected in 10 of 407 patients (2.5%) and objectively confirmed in two (0.5%).

CONCLUSIONS

The rate of venographic thrombosis in the absence of thromboprophylaxis after major joint surgery in Asian patients is similar to that previously reported in patients in Western countries.

Successful control of postsurgical bleeding by recombinant factor VIIa in a renal failure patient given low molecular weight heparin and aspirin

An end-stage renal failure patient with lupus nephritis was treated with low molecular weight heparin (LMWH) and aspirin for cardiac ischemia. She was then subjected to surgery to recreate a new arteriovenous fistula for dialysis 1 day after discontinuing LMWH and aspirin. Severe postsurgical bleeding required wound reexploration and multiple transfusions of blood products, which nevertheless, failed to arrest bleeding. Recombinant factor VIIa (rFVIIa) as a bolus dose of 120 microg/kg successfully secured hemostasis. Bleeding in this patient was attributed to the accumulation of low molecular weight heparin activity from poor renal clearance as well as the antiplatelet activity of aspirin. The potential of rFVIIa in securing hemostasis for excessive bleeding after use of these agents is promising.

New aspects of the blood coagulation cascade, anticoagulants and vein thrombosis in Asia

PURPOSE

This review describes recent views on blood coagulation and abnormalities of its physiological control that predispose to thrombosis, suggests that venous thrombosis and pulmonary embolism are more prevalent in Asia than was previously thought, and examines recent trials of novel anticoagulants for thrombosis prevention.

SOURCES

'Medline' was used to search for publications in English or with English language abstracts.

CONTENT AND CONCLUSIONS

The study of blood coagulation is basic to understanding clotting and bleeding disorders, their prevention and treatment. Tissue factor, factor Xa, and thrombin are pivotal; together with physiological controls (positive and negative feedback loops, and natural anticoagulants) that first enhance thrombin generation but then preserve vessel patency by limiting haemostatic plug formation to areas of injury. Abnormalities in these mechanisms can increase thrombosis risk (thrombophilia). The traditional impression that venous thromboembolism is rare in Asia has been reinforced by the rarity of thrombophilic genetic polymorphisms outside of European populations. Nevertheless, there is increasing evidence for an increasing prevalence of symptomatic vein thrombosis and pulmonary embolism in Asia, and that thrombosis rates in 'high risk' clinical settings among elderly patients (as after major joint surgery or a stroke) now approach levels reported from the West. This indicates the need for greater clinical awareness of these conditions. Drugs now used routinely for thrombosis prevention in the West (especially low molecular weight heparins) are effective and relatively safe. New anticoagulants were even more effective in recent trials. There is urgent need for studies in Asia that define the locally relevant benefits and hazards of the increasing range of agents now available.

Deep vein thrombosis is not rare in Asia--the Singapore General Hospital experience

INTRODUCTION

Venous thromboembolism (VTE) is perceived to be rare in Asia, but our recent clinical experience at Singapore General Hospital (SGH) suggests otherwise. Between 1996 and 1997, there were 388 cases of confirmed deep vein thrombosis (DVT).

MATERIALS AND METHODS

All patients with symptomatic DVT confirmed by duplex ultrasound studies from January 1996 to December 1997 were retrospectively studied. Their case notes were searched for a record of predisposing risk factors.

RESULTS

Ultrasound imaging indicated acute thrombosis in 320 patients (82.5%), and previous, but not acute thrombosis in 68 patients (17.5%). The overall frequency rate of acute DVTs was 15.8 per 10,000 hospital admissions. The average age of patients with acute thrombosis was 58.2 years. 9.2% of patients developed pulmonary embolism (PE). Their most frequently recorded clinical predispositions were immobilisation (67%), malignancy (33%) and recent surgery (30%). One hundred and thirty patients were tested for antithrombin, protein C or protein S deficiency, and the presence of antiphospholipid antibody and 45 (35%) were found to have at least 1 positive result.

CONCLUSION

DVT is not uncommon in Singapore. Our frequency rate of acute DVT of 15.8 per 10,000 admissions is much higher than previously reported rates of 2.8 and 7.9 per 10,000 admissions in 1990 and 1992, respectively. These findings confirm the need for increased awareness of VTE in Asian populations, and support the relevance of systematic studies of thrombosis risk and prophylaxis in Asia.

Idiopathic thrombocytopenia in pregnancy

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder in which antiplatelet autoantibodies bind to the antigens on platelet surfaces, resulting in their destruction. It is one of the most common autoimmune disorders that physicians manage today. Although it can present itself at any age, it tends to occur in young women. Hence, it commonly affects women in the childbearing age group. It is a haematological disorder for which diagnostic and treatment strategies are not well defined. In the past decade, there have been attempts for consensus in the management of patients with ITP, resulting in practice guidelines being published. The management of pregnant patients with ITP, however, has its special problems with the added responsibility of caring for 2 lives, the mother and her fetus. The choice of drugs is limited to those without teratogenic risks to the fetus and the overall aim is to prevent haemorrhage in both mother and fetus during the antenatal and peripartum periods. There are more data now to show that invasive procedures do not necessarily reduce fetal bleeding risk and are associated with more maternal morbidities, thus favouring the trend towards more conservative management.

Clinical update on deep vein thrombosis in Singapore

Venous thromboembolism (VTE) is thought to be a rare occurrence in Asian patients. The clinical features of VTE are elusive and the disease often unsuspected. Objective testing such as the duplex ultrasound scans and pulmonary imaging are necessary as clinical diagnosis alone is inaccurate. Fatality can occur in untreated patients not suspected of the disease as shown by our post-mortem studies. Indeed VTE is one of the leading causes of maternal mortality in Singapore. There is a rising trend in the incidence of VTE in Asia. Initial studies found an incidence of about 3 per 10,000 hospital admissions in Hong Kong and Malaysia in 1988 and 1990, respectively; rising to 8 and 15.8 per 10,000 hospital admissions in Singapore 1992 and 2000, respectively. The major risk factors for developing deep vein thrombosis (DVT) in our patients are immobilisation, surgery and malignancy. While Factor V Leiden mutation and mutation at position 20,210 in the prothrombin gene are found to be extremely rare in Chinese, the rest of the thrombophilia has not been formally studied. Studies in Singapore reported rates of 3% to 7% of DVT after general surgery, 9.7% after hip surgery and 14% after total knee replacement surgery. It is difficult to compare with studies from other centres because of differences in patient selection and diagnostic criteria. Studies in Singapore showed that the use of prophylactic low molecular weight heparin completely abolished the occurrence of DVT for patients undergoing total knee replacement and colorectal surgery without an increase in bleeding complications. In conclusion, VTE is not an uncommon problem here. Major acquired risk factors do not differ from the Caucasian populations. VTE is a preventable disease and a better understanding of its epidemiology, patient-risk factors and biological factors will allow better management of this condition.

Case report on recombinant coagulation factor VIIa in the treatment of three haemophilia A patients with inhibitors in Singapore

INTRODUCTION

We report the first experiences with use of recombinant coagulation Factor VIIa (rFVIIa) in the treatment of haemophilia A patients with inhibitors in Singapore and discuss observations in 3 patients.

CLINICAL PICTURE

Case 1 bled on two separate occasions into his neck muscles and vocal cord. Case 2 had gross haematuria from bleeding in the renal calyxes. Case 3 bled into the parotid muscles.

TREATMENT

rFVIIa in doses, ranging from 50 ug/kg to 90 ug/kg, at different dosing intervals, were used.

OUTCOME

Excellent responses were seen in doses of 70 and 90 ug/kg.

CONCLUSIONS

rFVIIa is highly effective, both clinically and cost-wise, in the treatment of these patients.

Evaluation on the use of a portable unit versus the laboratory for the monitoring of International Normalized Ratio (INR) in orally anticoagulated patients

INTRODUCTION

Measuring the International Normalized Ratio (INR) through a laboratory requires venipuncture and takes about 1 hour for results to be available. A portable monitor (CoaguChek Plus System), which measures the INR using fingerstick samples, is evaluated in this study to determine its clinical significance in anticoagulated and non-anticoagulated individuals. The hospital's outpatient and inpatient laboratories were also compared in the study.

MATERIALS AND METHODS

Paired venous and capillary blood INRs were performed on anticoagulated patients using the monitor and the Singapore General Hospital (SGH) outpatient and inpatient laboratories (OPS and IPS labs). Paired INRs of control samples were also performed using the monitor and the IPS lab.

RESULTS

We plotted the difference in INR by the 2 methods (monitor and OPS lab, n = 91) against their mean, and calculated the limits of agreement (95% of the difference would lie between -0.90 to 0.70). After a logarithmic transformation on the data, we found that for 95% of the cases, the OPS lab would differ from the monitor by 13% below to 14% above. There was also a marginal difference (95% limits of agreement of -0.14 to 0.10) when we compared the INR obtained from OPS and IPS laboratories (n = 43). Our control sample (n = 19) showed that the 95% confidence interval for the bias was -0.04 to 0.10.

CONCLUSION

The monitor should be used with caution in patients with INR > 3. We suggest use of the monitor in situations where the non-anticoagulated state of a patient needs to be measured. There is a difference in INR measured by laboratories within the same institution.

Management of neurocytomas: case report and review of the literature

The purpose of this report is to review the available literature on the presentation, pathology, and treatment of central nervous system (CNS) neurocytomas. A case report of an extraventricular neurocytoma is presented along with a comprehensive literature search of patients with a diagnosis of CNS neurocytoma. CNS neurocytomas are rare neoplasms, with fewer than 240 cases reported in the literature. The majority of neurocytomas are found in the ventricular system of the brain. Immunohistochemistry is frequently used to help distinguish this tumor from other CNS neoplasms. MIB-1 proliferation index is commonly used in an attempt to predict biologic behavior. Little is known about the management of patients with this tumor, because most reports are from the pathologic literature and contain sparse information regarding clinical management. Neurocytomas are rare CNS tumors with varied biologic behavior. MIB-1 index may help direct adjuvant therapy. An excellent prognosis can be expected if a gross total resection is achieved. Postoperative radiation therapy (RT) may be considered after subtotal resection. Otherwise, RT is an option for medically inoperable or recurrent disease.

Monoclonal antibodies against different epitopes of nonstructural protein sigmaNS of avian reovirus S1133

Ten monoclonal antibodies (MAbs) were prepared against the nonstructural protein sigmaNS of avian reovirus S1133. Eight of them were selected for two-way competitive binding assay after coupling with horseradish peroxidase. The results allowed the definition of three epitopes, designated A, B, and C. Blocking assay of poly(A)-Sepharose binding activity of sigmaNS with MAbs indicated that MAb recognizing epitope B was able to block poly(A) oligomer binding, suggesting that epitope B is involved in ssRNA binding of sigmaNS. An immuno-dot binding assay was used to analyze the effect of denaturation on antibody recognition of the epitopes. All MAbs bound to protein sigmaNS in its native form. After denaturation by boiling in SDS and 2-mercaptoethanol, the binding of MAbs recognizing epitopes B and C was not affected. The reactivity of MAbs recognizing epitope A was fully abolished by denaturation. These results suggest that the binding of MAbs directed against epitope A is conformation-dependent; however, the recognition by MAbs of epitopes B and C is not conformation-dependent. In addition, the results from the cross-reactivity of MAbs to heterologous avian reovirus strains suggest that the three epitopes are highly conserved among these virus strains.

Topical bactrim versus trimethoprim and sulfonamide against nocardia keratitis

PURPOSE

The conventional treatment of Nocardia keratitis is with topical sulfonamides. Recently, topical trimethoprim and sulfamethoxazole (Bactrim) has been suggested as treatment. This study compares the in vitro efficacy against Nocardia asteroides of Bactrim and various ratios of trimethoprim and a sulfonamide.

METHODS

Antibiotic disks were soaked with various ratios of trimethoprim and sulfacetamide sodium. They contained trimethoprim alone, sulfacetamide sodium alone, and both trimethoprim and sulfacetamide sodium at ratios of 1:40, 1:20, and 1:5. Disks containing Bactrim were also prepared. Each disk was placed on blood agar plates streaked with N. asteroides. The plates were incubated at 37 degrees C for 72 hours and then examined.

RESULTS

Trimethoprim alone showed minimal effect. Sulfacetamide sodium alone had a clearance zone of 12 mm. The plates of trimethoprim and sulfacetamide sodium at ratios of 1:40, 1:20, and 1:5 had clearance zones of 14 mm, 17 mm, and 27 mm, respectively. Bactrim had a clearance zone of 70 mm.

CONCLUSION

Trimethoprim or sulfacetamide sodium alone is not as effective as both drugs together. As the ratio of the two drugs was changed, potency differed against Nocardia organisms. Bactrim was the most effective antibiotic against Nocardia organisms. It should be the recommended agent for the treatment of Nocardia keratitis.

Bacterial Polysaccharides as Vaccines — Immunity and Chemical Characterization

Studies on protective immunity and biochemical characterization of bacterial capsular polysaccharides have led to significant contributions to understanding of the mechanisms of infectious diseases and development of effective vaccines. Immunity to encapsulated bacteria is related to antibody response to polysaccharide (PS) antigen, interactions with T- and B-lymphocytes, and host defense mechanisms. Meningococcal, pneumococcal and Salmonella vi PSs and Haemophilus type b PS-protein conjugate vaccines have been licensed and provided effective immunity for prevention of these bacterial infections. Capsular PSs are cell-surface polymers consisting of oligosaccharide repeating units. Many PSs are highly polar and hydrophilic and interfere with cell-to-cell interactions with phagocytes. Most pneumococcal PSs are negatively charged and possess acidic components such as D-glucuronic acid and phosphate in phosphodiester bonds. Extensive immunologic cross-reactivity has been observed among bacterial capsular PSs. In infants the antibody responses to most capsular PSs are generally poor. Enhanced immunogenicity of PS antigens can be achieved through PS-protein conjugate vaccines, immunization during a critical period of perinatal development and effective antigen delivery system.

Fewer symptoms occur in same-serotype recurrent streptococcal tonsillopharyngitis

BACKGROUND

Most patients with acute rheumatic fever report no antecedent pharyngitis.

OBJECTIVE

To determine the clinical and microbiological characteristics of recurrent group A beta-hemolytic streptococcal (GABHS) tonsillopharyngitis.

DESIGN

Prospective randomized trial.

SUBJECTS

Symptoms were recorded and throat cultures were obtained at 4 to 6, 18 to 21, and 32 to 35 days following the start of treatment. A subset of 60 patients with subsequent GABHS episodes occurring were evaluated for a 0.2-or greater log rise in either antistreptolysin O or anti-deoxyribonuclease B titer to confirm a bona fide recurrence.

RESULTS

Sixteen (27%) of 60 patients had recurrent GABHS tonsillopharyngitis of the same serotype that occurred 21 days or longer following the onset of the initial GABHS infection and was associated with a 0.2- or greater log rise in either antistreptolysin O or anti-deoxyribonuclease B titer, indicating bona fide recurrent infection; these recurrences all occurred within 55 days. Fewer patients with recurrent GABHS pharyngitis of the same serotype had headache (P =.02), sore throat (P =.006), fever (P =. 008), pharyngeal erythema (P<.001), pharyngeal edema (P<.001), pharyngeal exudate (P =.04), and adenitis (P =.03) compared with the initial episode. Chills, stomachache, scarlatina, tonsillar enlargement, and palatal petechiae were similar for both episodes.

CONCLUSIONS

Fewer symptoms occur during recurrent GABHS pharyngitis of the same serotype compared with the initial infection. These patients may be less likely to seek physician attention, yet their infections put them at risk for sequelae.

Costs of illness due to Bordetella pertussis in families

OBJECTIVE

To assess costs of pertussis morbidity among families in a community setting.

DESIGN

Prospective survey.

RESULTS

Sixty-nine families (87 individuals) were studied. Twelve of 14 families with household contacts included an ill adolescent or parent. This individual was the first identified pertussis case within the household in 8 families. A family member required an average of 1.6 visits before (range, 0-7 visits) and after (range, 0-9 visits) pertussis was diagnosed; children younger than 1 year needed 2.5 and 2 visits, respectively. Symptomatic improvement occurred after a mean of 31 days (range, 4-134 days) after pertussis diagnosis and full recovery after a mean of 66 days (range, 5-383 days). Adults experienced the longest recovery time (median, 93 days) compared with other age groups. The average medical costs for an infant, child, adolescent, and adult were $2822, $308, $254, and $181, respectively. Parents lost an average of 6 workdays (range, 1-35 days) to care for an ill child; for these parents, costs associated with work loss averaged $767 per family. An average of 1.7 and 0.7 lost workdays accrued to bring an ill child to a physician's office and the emergency department, respectively. A majority (58%) of parents working while family members were ill with pertussis reported decreased work productivity ranging from 25% to 99%. Work-related costs contributed more than 60% of the overall costs of pertussis.

CONCLUSIONS

The adverse financial effect of pertussis on 69 families in Monroe County, New York, was $145,903 ($2115 per family) and supports the need for booster immunizations in adolescents and adults. Arch Fam Med. 2000;9:989-996

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.

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.

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.

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.

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.

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.

Molecular characterization of KEX1, a kexin-like protease in mouse Pneumocystis carinii

Expression screening of a Pneumocystis carinii-infected mouse lung cDNA library with specific monoclonal antibodies (mAbs) led to the identification of a P. carinii cDNA with extensive homology to subtilisin-like proteases, particularly fungal kexins and mammalian prohormone convertases. The 3.1 kb cDNA contains a single open reading frame encoding 1011 amino acids. Structural similarities to fungal kexins in the deduced primary amino acid sequence include a putative proenzyme domain delineated by a consensus autocatalytic cleavage site (Arg-Glu-Lys-Arg), conserved Asp, His, Asn and Ser residues in the putative catalytic domain, a hydrophobic transmembrane spanning domain, and a carboxy-terminal cytoplasmic domain with a conserved tyrosine motif thought to be important for localization of the protease in the endoplasmic reticulum and/or Golgi apparatus. Based on these structural similarities and the classification of P. carinii as a fungus, the protease was named KEX1. Southern blotting of mouse P. carinii chromosomes localized kex1 to a single chromosome of approximately 610 kb. Southern blotting of restriction enzyme digests of genomic DNA from P. carinii-infected mouse lung demonstrated that kex1 is a single copy gene. The function of kexins in other fungi suggests that KEX1 may be involved in the post-translational processing and maturation of other P. carinii proteins.

Self-assembly of the infectious bursal disease virus capsid protein, rVP2, expressed in insect cells and purification of immunogenic chimeric rVP2H particles by immobilized metal-ion affinity chromatography

A gene encoding a structural protein (VP2) of a local strain (P3009) of infectious bursal disease virus (IBDV) was cloned and expressed using the baculovirus expression system to develop a subunit vaccine against IBDV infection in Taiwan. The expressed rVP2 proteins formed particles of approximately 20-30 nm in diameter. Those particles were partially purified employing sucrose density gradient ultracentrifugation, and the purified particles were recognized by a monoclonal antibody against the VP2 protein of IBDV P3009. To facilitate the purification of the particles, the VP2 protein was engineered to incorporate a metal ion binding site (His)(6 )at its C-terminus. The chimeric rVP2H proteins also formed particles, which could be affinity-purified in one step with immobilized metal ions (Ni(2+)). Particle formation was confirmed by direct observation under the electron microscope. The production level of rVP2H protein was determined to be 20 mg/L in a batch culture of Hi-5 cells by quantifying the concentration of the purified proteins. The chicken protection assay was performed to evaluate the immunogenicity of the rVP2H protein. When susceptible chickens were inoculated with the recombinant rVP2H proteins (40 microg/bird), virus-neutralizing antibodies were induced, thereby conferring a high level of protection against the challenge of a very virulent strain of IBDV. In conclusion, the most significant finding in this work is that both of the expressed rVP2 and rVP2H proteins can form a particulate structure capable of inducing a strong immunological response in a vaccinated chicken.

Synthesis in Escherichia coli of avian reovirus core protein varsigmaA and its dsRNA-binding activity

The genome segment S2 of p6ian reovirus (ARV) S1133 was cloned and sequenced. The entire S2 nucleotide sequence is 1325 bp long with one long open reading frame that encodes a protein of 415 amino acids, corresponding to varsigmaA, a major core protein of ARV. S2 possesses a pentanucleotide, TCATC, at the 3'-terminus of its plus strand, common to other known genome segments of ARV and to 10 genome segments of mammalian reovirus. Amino acid sequence analysis revealed that varsigmaA contains a carboxy-terminal region (one-fourth of the protein) that is formed from alpha-helices and beta-turns, and the remainder (three-fourths of the protein) is formed predominantly from beta-strands and beta-turns. Analysis of binding activity to poly(rI)-poly(rC)-agarose suggested that ARV protein A present in total virus-infected chicken embryo fibroblasts (CEF) had dsRNA-binding activity. To further characterize the binding activity, protein varsigmaA was subsequently expressed in Escherichia coli BL21(DE3) cells as a fusion protein and isolated by metal chelate affinity chromatography. The expressed protein evarsigmaA was further purified through a Superdex 75 HR 10/30 column after digestion of the purified fusion peptide with enterokinase. The expressed protein evarsigmaA has the same molecular weight as virion protein varsigmaA purified from ARV-infected CEF and is indistinguishable from virion protein varsigmaA by immunoblot analysis. The evarsigmaA binds cooperatively alpha (32)P-labeled dsRNA probe produced by run-off transcription of clone pGEM-3Zf(+)S4. The binding reaction is blocked by homologous ARV dsRNA or heterologous infectious bursal disease virus dsRNA and poly(rI)-poly(rC), but not by salmon sperm DNA. The results indicate that the expressed protein evarsigmaA has dsRNA-binding activity similar to that of varsigmaA obtained from infected cells, and its binding is sequence-independent.

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.

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.

Relevance of Film Pressures to Interfacial Tension, Miscibility of Liquids, and Lewis Acid-Base Approach

In this paper, we demonstrate the spreading pressure and interfacial film pressure to be profoundly relevant to interfacial tension, miscibility of liquids, and the Lewis acid-base approach. For immiscible liquid-solid and liquid-liquid systems, we prefer to employ Harkins' spreading model containing the equilibrium spreading pressure pie. With the inclusion of pie, we can also improve the Lewis acid-base approach for hydrogen-bonding, proposed by van Oss, Chaudhury, and Good. We establish an acidity-basicity scale for the initial surface tension by taking pie into account, and we further calculate interfacial tensions for liquid pairs containing formamide or dimethyl sulfoxide (DMSO) with dispersion components cited in Fowkes et al.'s later publication. However, for initially immiscible liquid-liquid systems, the Harkins model does not apply, and we propose, instead, an adsorption model, which requires the interfacial tension to be varying and surface tensions of the bulk liquids at a distance from the interface to remain unchanged. Thus, the difference between the initial and equilibrium interfacial spreading coefficients (Si) equals the equilibrium interfacial film pressure (pii)e, and that difference also equals that of the two interfacial tensions. For liquid-liquid systems, we can choose either of these two models depending on the miscibility of liquids. According to our adsorption model, there should be two interfacial tensions. The initial (or calculated) interfacial tension can be positive or negative, while the equilibrium (experimental) interfacial tension can reach zero. The former has more predictive value than the latter. A negative, initial interfacial tension is delineated to favor miscibility or spontaneous emulsification, but it tends to revert to zero instantaneously. Furthermore, a slightly positive, initial interfacial tension can also lead to miscibility, if (pii)e can help reduce it to a zero equilibrium interfacial tension. We have also found a new important relationship between (pii)e and pie on the basis of the Laplace equation. We also attempt to calculate with our model the (pii)e's for at least 34 liquid pairs, by assuming the published interfacial tensions to be reasonable equilibrium values. Finally, the equilibrium spreading pressure pie for the liquid-solid interface, or the (pii)e for the liquid-liquid interface, appears to be the missing link between the wetting thermodynamics and linear free energy solvatochromic relationship (LFER). We have shown the pie or (pii)e of the former to be the equivalent of the Pi*, polarity/dipolarity parameter, of the latter. Our findings about the correlation between the surface tension component (STC) concept and LFER have provided a new support for the STC theory. Copyright 1999 Academic Press.

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.

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).

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.

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.

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.

Cloning and nucleotide sequencing of the S4 genome segment of avian reovirus S1133

The sequence of RNA genome segment S4 of the avian reovirus (ARV) strain S1133 was determined. S4 RNA is 1185 base pairs long and contains one open reading frame encoding a protein of 367 amino acid residues (40.6 kDa), the similar size as the known S4 gene product (sigma NS), with a net charge of -1 at neutral pH. The S4 RNA sequence possesses a pentanucleotide sequence UCAUC at the 3'-terminus of its plus strand like in ARV S1 and S3 segments and ten segments of mammalian reovirus (MRV). The predicted amino acid sequence comparison revealed that the homology is 44.02%, 45.71%, and 42.33% for ARV sigma NS and three serotypes of MRV sigma NS, respectively. The relatively high content of alpha-helix structure in the C-terminal portion of ARV sigma NS suggests that this protein may functionally relate to MRV sigma NS. Northern blot hybridization showed that a 32P-labeled cDNA insert S4-49 from ARV S4 RNA cross-hybridized with the corresponding RNA segments of all seven strains of ARV tested.

Detection of avian reovirus RNA and comparison of a portion of genome segment S3 by polymerase chain reaction and restriction enzyme fragment length polymorphism

A reverse transcription-polymerase chain reaction (RT-PCR) was established to amplify a 672-base pairs fragment on the segment S3 of avian reovirus (ARV). The amplified fragments were detected in nine strains of ARV as well as three tendon tissue specimens, indicating that the primer regions were well conserved. The RT-PCR was able to detect as low as 0.2 pg using an ethidium bromide stained gel. The detection limit could be enhanced further to 0.04 pg by hybridisation after southern transfer. The amplified DNA fragments from nine ARV strains and two tissue specimens showed different restriction enzyme cleavage patterns. Analysis of the data revealed that these 11 strains were classified into four groups. The results suggest that PCR followed by restriction enzyme analysis may provide a simple and rapid method for the characterisation of ARV isolates.

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.

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.

An Easy-To-Use Combination Four-Terminal-Pair/Two-Terminal-Pair AC Transformer Bridge

A new four-terminal-pair bridge, capable of achieving a relative standard uncertainty of 1×10^-9, was constructed at the National Institute of Standards and Technology by converting a two-terminal-pair bridge. The conversion requires only the addition of components which are easily removed if two-terminal-pair measurements are to be made. The design and testing of this bridge is described. The new four-terminal-pair bridge requires fewer auxiliary balances than the present four-terminal-pair bridge employed at NIST, which makes it much easier to use. This new design can be used to compare capacitance, resistance, and inductance standards.