Hospital readmissions for fluid overload among individuals with diabetes and diabetic kidney disease: risk factors and multivariable prediction models

AIMS

Hospital readmissions due to recurrent fluid overload in diabetes and diabetic kidney disease can be avoided with evidence-based interventions. We aimed to identify at-risk patients who can benefit by developing risk prediction models for readmissions for fluid overload in people living with diabetes.

METHODS

Single-center retrospective cohort study of 1531 adults with diabetes and hospitalized for fluid overload, including congestive heart failure, pulmonary edema and generalized edema, between 2015 and 2017. The multivariable regression models for 30-day and 90-day readmission for fluid overload were compared with the LACE score for discrimination, calibration, sensitivity, specificity and net reclassification index (NRI).

RESULTS

Readmissions for fluid overload within 30 days and 90 days occurred in 8.6% and 17.2% of patients with diabetes, and 8.2% and 18.3% of patients with diabetic kidney disease, respectively. After adjusting for demographics, comorbidities, clinical parameters, and medications, a history of alcoholism (HR 3.85, 95% CI 1.41-10.55) and prior hospitalization for fluid overload (HR 2.50, 95% CI 1.26- 4.96) were independently associated with 30-day readmission in patients with diabetic kidney disease, as well as in individuals with diabetes. Additionally, current smoking, absence of hypertension and high-dose intravenous furosemide were also associated with 30-day readmission in individuals with diabetes. Prior hospitalization for fluid overload (HR 2.43, 95% CI 1.50-3.94), cardiovascular disease (HR 1.44, 95% CI 1.03-2.02), eGFR ≤45 ml/min/1.73 m2 (HR 1.39, 95% CI 1.003-1.93) were independently associated with 90-day readmissions in individuals with diabetic kidney disease. Additionally, thiazide at discharge reduced 90-day readmission in diabetic kidney disease while high-dose intravenous furosemide predicted 90-day readmission in diabetes. The clinical and clinico-psychological models for 90-day readmission in individuals with diabetes and diabetic kidney disease had better discrimination and calibration than the LACE score. The NRI for the clinico-psychosocial models to predict 30- and 90-day readmissions in diabetes were 22.4% and 28.9%, respectively. The NRI for the clinico-psychosocial models to predict 30- and 90-day readmissions in diabetic kidney disease were 5.6% and 38.9%, respectively.

CONCLUSION

The risk models can potentially be used to identify patients at-risk of readmission for fluid overload for evidence-based interventions such as patient education or transitional care programs to reduce preventable hospitalizations.  .

Early repeat hospitalization for fluid overload in individuals with cardiovascular disease and risks: a retrospective cohort study

AIMS

Fluid overload is a common manifestation of cardiovascular and kidney disease and a leading cause of hospitalizations. To identify patients at risk of recurrent severe fluid overload, we evaluated the incidence and risk factors associated with early repeat hospitalization for fluid overload among individuals with cardiovascular disease and risks.

METHODS

Single-center retrospective cohort study of 3423 consecutive adults with an index hospitalization for fluid overload between January 2015 and December 2017 and had cardiovascular risks (older age, diabetes mellitus, hypertension, dyslipidemia, kidney disease, known cardiovascular disease), but excluded if lost to follow-up or eGFR < 15 ml/min/1.73 m2. The outcome was early repeat hospitalization for fluid overload within 30 days of discharge.

RESULTS

The mean age was 73.9 ± 11.6 years and eGFR was 54.1 ± 24.6 ml/min/1.73 m2 at index hospitalization. Early repeat hospitalization for fluid overload occurred in 291 patients (8.5%). After adjusting for demographics, comorbidities, clinical parameters during index hospitalization and medications at discharge, cardiovascular disease (adjusted odds ratio, OR 1.66, 95% CI 1.27-2.17), prior hospitalization for fluid overload within 3 months (OR 2.52, 95% CI 1.17-5.44), prior hospitalization for any cause in within 6 months (OR 1.33, 95% CI 1.02-1.73) and intravenous furosemide use (OR 1.58, 95% CI 1.10-2.28) were associated with early repeat hospitalization for fluid overload. Higher systolic BP on admission (OR 0.992, 95% 0.986-0.998) and diuretic at discharge (OR 0.50, 95% CI 0.26-0.98) reduced early hospitalization for fluid overload.

CONCLUSION

Patients at-risk of early repeat hospitalization for fluid overload may be identified using these risk factors for targeted interventions.

Fungus isolated from dermatomycoses: a 9-month prospective study at Hospital Melaka

INTRODUCTION

Dermatomycoses are common superficial cutaneous fungal infections which affect the skin, nails and human hairs. It affects 20 to 25% of the world population. The causative fungus varies geographically across the globe. Study on dermatomycoses is crucial to identify the aetiological fungus involved locally. The study aimed to determine the causative fungus of superficial fungal infections of the skin, nail and hair in patients presented to Hospital Melaka.

METHODS

This was a prospective study conducted from 15th January 2022 till 15th October 2022 at Dermatology Clinic, Hospital Melaka. Subjects with clinical dermatomycoses were included in this study. The samples were collected from skin, nails and hairs clinically affected by tinea corporis/cruris/pedis, onychomycosis and tinea capitis respectively. A potassium hydroxide (KOH) study was performed on the sample in which the fungal hyphae/yeast positive subjects were sent for fungal culture and fungal PCR test.

RESULT

A total of 222 clinical samples from skin, nails and hairs with a clinical suspicion of dermatomycoses yielded fungal hyphae/yeast in KOH. Majority of the samples were collected from skin (138, 62.2%), followed by nails (65, 29.3%) and hairs (19, 8.6%). Male to female ratio was 1.18: 1. The age ranged from 2 to 87 with the median of 55.5-yearsold. Out of 222 samples, 150 (67.6%) were fungal culture positive. From fungal culture positive samples, 87 samples were from tinea corporis, 50 samples were from onychomycoses and 13 samples were from tinea capitis. Trichophyton rubrum (39, 44.8%) was the commonest dermatophyte isolated in tinea corporis/cruris/pedis. Nondermatophyte moulds (NDM, 35, 70%) were the main fungi isolated in onychomycosis. Microsporum canis (7/53.8%) was the principal causative fungus among patients with tinea capitis. Among 150 fungal culture positive samples, 76 were fungal PCR positive. Only 38 samples consistently isolated same fungal species in both fungal culture and PCR test.

CONCLUSION

Majority of tinea corporis and tinea capitis fungal culture isolated dermatophytes, especially Trichophyton rubrum and Microsporum canis, respectively. Non-dermatophyte moulds were mainly isolated in onychomycosis.

Regional citrate anticoagulation vs systemic heparin anticoagulation for double-filtration plasmapheresis

INTRODUCTION

Double-filtration plasmapheresis (DFPP) has been utilized for immunomodulation in kidney transplantation. Anticoagulation is important to maintain circuit patency during DFPP. We aimed to compare the efficacy and safety of regional citrate anticoagulation (RCA) with systemic heparin anticoagulation during DFPP in kidney transplant recipients.

METHODS

A retrospective cohort study was conducted to compare the efficacy and safety of RCA (RCA-DFPP) to systemic heparin anticoagulation (Hep-DFPP) for DFPP among kidney transplant recipients in a single tertiary center.

RESULTS

A total of 112 sessions of DFPP were performed for 23 subjects, of which 62 sessions were RCA-DFPP and 50 sessions were Hep-DFPP. There were 13 sessions (11.6%) of premature circuit clotting, 10 sessions (16.1%) for RCA-DFPP and 3 sessions (6.0%) for Hep-DFPP (P = .10). All premature circuit clotting episodes occurred in subjects who underwent DFPP through a vascular catheter. Premature circuit clotting was associated with the use of a vascular catheter (odds ratio [OR] 14.2, 95% confidence interval [CI] 2.7-73.7; P < .01) and high postfilter ionized calcium (OR 12.7, 95% CI 1.4-112.5; P < .01). There was no major bleeding event. Hep-DFPP was associated with higher occurrence of hypocalcemia (OR 1.1, 95% CI 1.0-1.2; P < .01) and metabolic acidosis (OR 1.4, 95% CI 1.2-2.0; P = .04), while hypomagnesemia was more common for RCA-DFPP (OR 2.9, 95% CI 1.1-7.4; P = .03).

CONCLUSION

Amongst kidney transplant patients who receive DFPP therapy, RCA-DFPP may be comparable to Hep-DFPP for the maintenance of circuit patency. Functioning vascular access is vital in avoiding premature clotting of the circuit. Close monitoring of electrolyte imbalances and coagulopathy related to DFPP is recommended.

Effectiveness and acceptability of a multidisciplinary approach in improving the care of patients with advanced chronic kidney disease: a pilot study

OBJECTIVE

This study aimed at determining the feasibility of conducting a large-scale pragmatic effectiveness study on the implementation of multidisciplinary care (MDC) program for patients with advanced chronic kidney disease (CKD).

METHODS

This is a single-arm pre-post intervention design pilot study over 12 months. Participants with an estimated glomerular filtration rate (eGFR) between 11 and 20 ml/min/1.73m² were screened and recruited at the initial MDC clinic visit and followed for 12 months. Clinical parameters, KDQOL^™-36, questionnaires, and interviews were collected, administered, and analysed for enrolment and completion rates, baseline characteristics, implementation fidelity, adherence to CKD interventions, eGFR decline, CKD complications, health-related quality of life, and participants' acceptability of the program.

RESULTS

The study enrolment and completion rates were 43.1% (50/116 screened) and 66.0% (33/50 recruited) respectively. The participants had a mean age of 68.5 years (SD9.0) and a mean eGFR of 15.4 ml/min/1.73m²(3.2). After 12 months of MDC program, there was increased adherence to CKD interventions (difference  - 0.6(1.0), 95%CI  - 1.1,  - 0.1, p = 0.02). There was good participants' acceptability of the program with participants being more satisfied with the waiting time and having a better understanding of kidney failure after attending the program. No difference in the eGFR decline noted (difference 0.0 ml/min/1.73m²(5.3), 95%CI  - 1.9, 1.9, p = 1.00).

CONCLUSION

Our pilot data suggest increased adherence to CKD interventions and good acceptability to MDC program, albeit no difference in eGFR decline probably because of the small sample size. However, reasons for overall low enrolment and completion rates need to be explored and addressed while designing a future large-scale randomised controlled trial.

Regional Citrate Anticoagulation during Double-Filtration Plasmapheresis in Kidney Transplant Recipients: A Single-Center Retrospective Cohort Study

INTRODUCTION

Double-filtration plasmapheresis (DFPP) may be used for immunomodulation in kidney transplant (KTx). While DFPP reduces plasma product exposure, risk of circuit clotting merits adequate anticoagulation. Regional citrate anticoagulation (RCA) avoids the risks of systemic anticoagulation, but a protocol for RCA-DFPP is not previously widely described.

METHODS

We conducted a single-center retrospective cohort study involving adult (≥21 years old) KTx recipients who underwent RCA-DFPP from 2018 to 2020 to investigate efficacy and safety for an RCA protocol during DFPP in KTx recipients.

RESULTS

Fifty-one (85%) of 60 RCA-DFPP sessions in 17 patients completed without circuit clotting. Circuit clotting was associated with high post-filter ionized calcium (28 vs. 3.7%, odds ratio 10.1, 95% CI 1.1-89.4, p = 0.037). Hypo- and hypercalcemia developed in 5 (8.3%) and 8 (13.3%) sessions, respectively, but no adverse effects were noted despite severe hypocalcemia in one. There was no significant change in pre- and post-RCA-DFPP sodium, bicarbonate, albumin, and platelet levels. With regards DFPP procedure, prolongation of prothrombin time (PT) and activated partial thromboplastin time (aPTT) was observed following 38 (64.4%) and 12 (20.3%) sessions, respectively. Severely prolonged (>1.5 × upper limit normal) PT and aPTT were recorded in 2 sessions each. Expectedly, hypofibrinogenemia developed after 31 (51.7%) sessions: including 4 (6.7%) severe hypofibrinogenemia (<0.5 g/L). Two patients developed bleeding requiring blood product transfusion. The median total volume of fluids administered per session was 1.495 (1.373-1.612) L; post-RCA-DFPP significant weight gain of 0.5 (0-1.25) kg was noted. Diuretic was commenced or dose increased following 20 (33.3%) sessions for fluid balance management.

DISCUSSION/CONCLUSION

Protocol-based RCA for DFPP is feasible and safe in KTx recipients. However, DFPP-related coagulopathy can develop consequent to treatment; caution should be exercised for patients with bleeding risk. Close monitoring and management of the patients' electrolytes, especially hypocalcemia and hypomagnesemia, and fluid status is recommended.

Description of parallel and sequential configurations for concurrent therapeutic plasma exchange and continuous kidney replacement therapy in adults

Therapeutic plasma exchange (TPE) and continuous kidney replacement therapy (CKRT) are extracorporeal therapeutic procedures often implemented in management of patients. Critically ill patients may be afflicted with disease processes that require both TPE and CKRT. Performing TPE discontinuous with CKRT is technically easier, however, it disrupts CKRT and may compromise with CKRT efficiency or hemofilter life. Concurrent TPE with CKRT offers several advantages including simultaneous control of disease process and correction of electrolyte, fluid, and acid-base disturbances that may accompany TPE. Additionally, TPE may be performed by either centrifugation method or membrane plasma separation method. The technical specifications of these methods may influence the methodology of concurrent connections. This report describes and reviews two different approaches to circuit arrangements when establishing concurrent TPE and CKRT.

Chlorhexidine-impregnated sponge dressing for prevention of catheter exit-site infection in peritoneal dialysis patients: a pilot study

PURPOSE

The study aimed to examine effect of chlorhexidine dressing in the prevention of peritoneal dialysis (PD)-related infection in PD patients.

METHODS

This single-center pilot study recruited 50 incident PD patients to use weekly chlorhexidine dressing. The primary outcome was exit-site/tunnel infection rate. Secondary outcomes were peritonitis rate, time to first PD-related infection, infection-related hospitalization, technique and patient survival, adverse events, and chlorhexidine dressing acceptability. These clinical outcomes were compared with those of a historical cohort (2016-2017) using daily gentamicin cream.

RESULTS

A total of 50 patients were recruited to use chlorhexidine and followed up for one year. The exit-site/tunnel infection rate was 0.09 (95% confidence interval [CI] 0.02-0.22) and peritonitis rate was 0.07 (95% CI 0.01-0.19) episodes per patient-year with chlorhexidine dressing. The 1-year infection-free survival rates for exit-site/tunnel infection and peritonitis were 92% and 94%, respectively. The 1-year technique and patient survival rates were 86% and 96%, respectively. Overall, 12% of participants developed localized contact dermatitis with chlorhexidine. Most participants (73%) reported that chlorhexidine dressings were very acceptable. Compared to a historical cohort using gentamicin cream (n = 238), the chlorhexidine group had similar exit-site/tunnel infection rates (incidence rate ratio [IRR] 0.65, 95% CI 0.22-1.92) but had lower peritonitis rates (IRR 0.24, 95% CI 0.07-0.77), and lower PD infection-related hospitalization rates (IRR 0.21, 95% CI 0.06-0.69) after adjusting for age, sex, race, primary kidney disease, and diabetes mellitus.

CONCLUSION

Weekly chlorhexidine dressing was associated with acceptable PD-related infection outcomes and was well-accepted by patients, although had a 12% rate of delayed localized contact dermatitis.

TRIAL REGISTRATION NUMBER AND DATE

The study was registered under www.clinicaltrials.gov with the reference number of NCT03406520 on 23 January 2018.

Pathogenicity of an Indigenous Strain of the Entomopathogenic Fungus Metarhizium anisopliae (Hypocreales: Clavicipitaceae) (MET-GRA4 Strain) as a Potential Biological Control Agent Against the Red Palm Weevil (Coleoptera: Dryophthoridae)

Metarhizium anisopliae Metchnikoff (Hypocreales: Clavicipitaceae) is a fungal pathogen that causes disease in various insect pests, and it can be exploited and developed as a biological control agent to combat the red palm weevil, Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae). The study on indigenous isolates is crucial especially for development of bioinsecticides in the future. The M. anisopliae strain called MET-GRA4 was tested for pathogenicity against adult red palm weevil and treated in vitro with different spore viabilities. The isolates exhibited pathogenicity with 100% mortality 21 d postinfection. The median lethal time (LT50) for 85% viable spores was 8.6 d, while 39% viable spores had an LT50 value of 21.37 d, with 92 and 16.6% mycosis, respectively. The species MET-GRA4 strain was molecularly characterized using ITS1 and ITS4 from pure culture (Isolate A), mass-produced spores (Isolate B), and infected red palm weevil cadavers (Isolate C). The DNA sequences obtained matched M. anisopliae sequences, with 99% similarity. This new isolate of M. anisopliae has potential as a targeted bioinsecticide for management of red palm weevil.

Augmented Adsorptive Blood Purification during Continuous Veno-Venous Haemodiafiltration in a Severe Septic, Acute Kidney Injury Patient: Use of oXiris®: A Single Centre Case Report

The use of the oXiris® haemofilter during continuous veno-venous haemodiafiltration (CVVHDF) for acute kidney injury (AKI) and severe sepsis is not completely understood. Although this filter has in vitro adsorptive properties for blood-borne cytokines and other humoural mediators of sepsis, its clinical usefulness is uncertain. Given its inherent adsorptive limitation for septic mediators, we developed a CVVHDF protocol in which the oXiris haemofilter was electively changed every 12 h even though there was no clotting or adverse circuit pressures. Augmented filter membrane adsorption was conducted for 3 consecutive days. We treated a critically ill patient with severe sepsis secondary to a gram-negative bacterial infection and sepsis-associated acute kidney injury (SA- AKI) in this way. The patient required high-dose vasopressor support, required mechanical ventilation, had received 12 h of CVVHDF with conventional M100 haemofilter, was on broad spectrum antibiotics and other conventional intensive care unit (ICU) care, prior to institution of the frequent oXiris haemofilter change protocol. Following the start of elective 12 hourly oXiris filter change, the patient showed reduction in the need for vasopressor and by Day 4 of this SA- AKI frequent filter change protocol, vasopressor requirement ceased, he was extubated. He survived ICU and but not hospital stay. To this end, more clinical studies are needed.

Low efficacy of delthamethrin-treated net against Singapore Aedes aegypti is associated with kdr-type resistance

There has been a worldwide surge in the number and severity of dengue in the past decades. In Singapore, relentless vector control efforts have been put in to control the disease since the 1960's. Space spraying, fogging, chemical treatment and source reduction are some commonly used methodologies for controlling its vectors, particularly Aedes aegypti. Here, as we explored the use of a commercially available delthamethrin-treated net as an alternative strategy and the efficacy of the treated net was found to be limited. Through bioassays and molecular studies, the failure of the treated net to render high mortality rate was found to be associated with the knockdown resistance (kdr) mutation. This is the first report of kdr- mutations in Singapore's Ae. aegypti. At least one point mutation, either homozygous or heterozygous, at amino acid residue V1016G of DIIS6 or F1269C of DIIIS6 was detected in 93% of field strains of Ae. aegypti. Various permutations of wild type and mutant amino acids of the four alleles were found to result in varying degree of survival rate among local field Ae. aegypti when exposed to the deltamethrin treated net. Together with the association of higher survival rate with the presence of both V1016G and F1269C, the data suggest the role of these mutations in the resistance to the deltamethrin. The high prevalence of these mutations were confirmed in a country wide survey where 70% and 72% of the 201 Ae. aegypti analysed possessed the mutations at residues 1016 and 1269 respectively. The highest mutated frequency combination was found to be heterozygous alleles (VG/FC) at both residues 1016 and 1269 (37.8%), followed by homozygous mutation at allele 1269 (24.4%) and homozygous mutation at allele 1016 (22.9%). The kdr- type of resistance among the vector is likely to undermine the effectiveness of pyrethroids treated materials against these mosquitoes.

DNA-based analyses of molds in Singapore public buildings results in a proposed Singapore Environmental Relative Moldiness Index

Dust samples (n=75) were collected from shopping malls, hotels and libraries in Singapore and then analyzed using Mold Specific Quantitative Polymerase Chain Reaction (MSQPCR) for the 36 molds that make up the Environmental Relative Moldiness Index (ERMI). Most of these molds (23/36) occur at similar rates in Singapore and the United States. A Singapore Environmental Relative Moldiness Index (SERMI) is proposed which might be divided into low (<18), medium (18 to 28) and high (>28) mold burden categories but more samples will help to refine these categories.

Bioassay and biochemical studies of the status of pirimiphos-methyl and cypermethrin resistance in Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Singapore

Aedes (Stegomyia) aegypti (Linnaeus) and Ae. (Stegomyia) albopictus (Skuse) were sampled from five regions of Singapore (Central, North East, North West, South East and South West) and tested with diagnostic concentrations of the technical grade insecticides, pirimiphos-methyl and cypermethrin. Biochemical assays were performed on the same populations of Ae. aegypti and Ae. albopictus to determine activities of detoxifying enzymes, including non-specific esterase (EST), monooxygenase (MFO) and acetylcholinesterase (AChE). The diagnostic test showed that all Ae. aegypti populations were susceptible to pirimiphos-methyl (mortality = 99 to 100%), but resistant to cypermethrin (mortality = 11 to 76%). Resistance to pirimiphos-methyl was observed in all Ae. albopictus populations (mortality = 49 to 74%) while cypermethrin resistance was detected in most Ae. albopictus populations (mortality = 40 to 75%), except those from Central (mortality = 86%) and South East (mortality = 94%) showing incipient resistance. The biochemical assays showed that there was significant enhancement (P < 0.001) of MFO activity in pyrethroid-resistant Ae. albopictus populations and most Ae. aegypti populations. The biochemical assay results suggested that AChE could play a role in pirimiphos-methyl resistance of Ae. albopictus in South West, South East and North East regions. The small but significant increase in EST activities in Ae. aegypti from all regions suggest that it may play a role in the observed cypermethrin resistance.

A novel mosquito feeding system for routine blood-feeding of Aedes aegypti and Aedes albopictus

A novel mosquito feeding system for routine blood-feeding of Aedes aegypti and Aedes albopictus was developed and evaluated. The system consisted of a collagen membrane casing filled with specific pathogen free (SPF) mini-pig blood, which is warmed by a simple in-house designed heating device. Blood feeding rate, fecundity, survival rate and hatchability of Ae. aegypti and Ae. albopictus colonies maintained by the feeding system were compared with those raised by conventional guinea pig feeding method. Aedes aegypti, displayed a significant difference in the feeding rate when offered blood meal using the membrane feeding (85.3%) and the guinea pig feeding (96.2%) methods (P=0.012). Though the feeding rate was reduced, the level was acceptable for maintenance of laboratory colonies. There was no significant difference in the fecundity (P=0.556), survival rate (P=0.715), and hatchability (P=0.932) between the two methods. For Ae. albopictus, the two feeding methods yielded no significant difference for the three parameters (fecundity, survival rate and hatchability=0.887, 0.580 and 0.564, respectively). Hence, we conclude that this simple collagen based membrane blood feeding system can be used for routine colonization of laboratory strains of Ae. aegypti and Ae. albopictus.

Environmental surveillance and molecular characterization of Legionella in tropical Singapore

Legionnaires' disease is often acquired by inhalation of legionellae from a contaminated environmental source. In recent years, Singapore has seen an increase in the use of aerosol-generating fixtures such as mist fans and spa pools. Poorly maintained and designed water fixtures could pose a public health threat to the community. In this study, we provided an update on the prevalence of Legionella in mist fans (N=28), household water heaters with storage tanks (N=19) and instantaneous heaters (N=30); and extended the survey to spa pools (N=29) and aerosol-generating fixtures in nursing homes (N=116). The prevalence of Legionella were 21.1% in water heaters with storage tanks, 24.1% in spa pools, 14.2% in mist fans and 3.3% in instantaneous heaters. Legionella was not detected in nursing homes. A total of 37 isolates were subjected to molecular characterization using Sequence-Based Typing (SBT) protocol from the European Working Group on Legionella Infections (EWGLI). This is the first study on the use of SBT protocol on environmental strains isolated from tropical South East Asia. The Legionella flora was very heterogenous. The overall diversity of the allelic profile was found to be 0.970 (95% CI 0.946 - 0.994). All known STs of our isolates have been associated with clinical cases in EWGLI database. The phylogenetic analysis showed that our novel environmental isolates were clustered with clinical STs that were previously reported in Europe, Japan, United Kingdom and United States etc. (in EWGLI database), suggesting that Legionella found in the environment of Singapore may potentially cause human disease.

New mosquito species records (Diptera: Culicidae) from Singapore

Nine species of mosquitoes in eight genera are recorded for the first time in Singapore. An additional two species were overlooked in a 1986 checklist for mosquitoes in Singapore, and one was described after 1986. Location and habitat data are provided for the nine new records. With the inclusion of these new records the number of species reported from Singapore is 137.

Is dengue a threat to the blood supply?

Dengue is the most common arthropod-borne infection worldwide, affecting at least 50 million people every year and endemic in more than 100 countries. The dengue virus is a single-stranded RNA virus with four major serotypes. Infection with one serotype confers homotypic immunity but not heterologous immunity, and secondary infection with another serotype may lead to more severe disease. The major route of transmission occurs through the Aedes aegypti mosquito vector, but dengue has also been transmitted through blood transfusion and organ transplantation. Infection results in a spectrum of clinical illness ranging from asymptomatic infection, undifferentiated fever, dengue fever, dengue haemorrhagic fever (DHF) to dengue shock syndrome (DSS). Dengue is spreading rapidly to new areas and with increasing frequency of major outbreaks. A trend has also been observed towards increasing age among infected patients. This will impact blood supply availability as more blood donors are deferred because of dengue infection or exposure to infection. The risk of transmission through transfusion of blood from asymptomatic viraemic donors will also increase. Although screening tests for dengue and effective pathogen reduction processes are now available for the blood supply, the value of implementing these costly measures needs to be carefully considered. Demand for platelets and fresh frozen plasma will rise with increasing number of DHF/DSS. Evidence-based guidelines for the clinical use of these blood components in the management of patients with DHF/DSS have not been well established, and inappropriate use will contribute to the challenges faced by blood services.

Role of InsP3 and ryanodine receptors in the activation of capacitative Ca2+ entry by store depletion or hypoxia in canine pulmonary arterial smooth muscle cells

BACKGROUND AND PURPOSE

Experiments were performed to determine if capacitative Ca(2+) entry (CCE) in canine pulmonary arterial smooth muscle cells (PASMCs) is dependent on InsP(3) receptors or ryanodine receptors as induction of CCE is dependent on simultaneous depletion of the functionally separate InsP(3)- and ryanodine-sensitive sarcoplasmic reticulum (SR) Ca(2+) stores in these cells.

EXPERIMENTAL APPROACH

Myocytes were isolated from canine pulmonary arteries using enzymatic procedures and were used within 8 h of preparation. Measurements of cytosolic Ca(2+) were made by imaging fura-2 loaded individual myocytes that were perfused with physiological buffered saline solution with or without Ca(2+).

KEY RESULTS

Treating myocytes with 10 microM cyclopiazonic acid (CPA), removing extracellular Ca(2+), and briefly applying 10 mM caffeine and 10 microM 5-hydroxytryptamine (5-HT) depleted SR Ca(2+) stores. Extracellular Ca(2+) reintroduction caused cytosolic [Ca(2+)] to elevate above baseline signifying CCE. The InsP(3) receptor inhibitors 2-aminobiphenylborate (50-75 microM; 2-APB) and xestospongin-C (20 microM; XeC) abolished CCE. Yet, CCE was unaffected by 10 microM or 300 microM ryanodine or 10 microM dantrolene, which modify ryanodine receptor activity. Higher dantrolene concentrations (50 microM), however, can inhibit both ryanodine receptors and InsP(3) receptors, did reduce CCE. In contrast, CCE activated by hypoxia was unaffected by XeC (20 microM).

CONCLUSIONS AND IMPLICATIONS

The results provide evidence that CCE activated by depletion of both InsP(3) and ryanodine SR Ca(2+) stores in canine PASMCs is dependent on functional InsP(3) receptors, whereas the activation of CCE by hypoxia appears to be independent of functional InsP(3) receptors.

The regulatory N-terminal region of the aromatic-responsive transcriptional activator DmpR constrains nucleotide-triggered multimerisation

The transcriptional promoting activity of DmpR is under the strict control of its aromatic effector ligands that are bound by its regulatory N-terminal domain. The positive control function of DmpR resides within the central C-domain that is highly conserved among activators of sigma(54)-RNA polymerase. The C-domain mediates ATP hydrolysis and interaction with sigma(54)-RNA polymerase that are essential for open-complex formation and thus initiation of transcription. Wild-type and loss-of-function derivatives of DmpR, which are defective in distinct steps in nucleotide catalysis, were used to address the consequences of nucleotide binding and hydrolysis with respect to the multimeric state of DmpR and its ability to promote in vitro transcription. Here, we show that DmpR derivatives deleted of the regulatory N-terminal domain undergo an aromatic-effector independent ATP-binding triggered multimerisation as detected by cross-linking. In the intact protein, however, aromatic effector activation is required before ATP-binding can trigger an apparent dimer-to-hexamer switch in subunit conformation. The data suggest a model in which the N-terminal domain controls the transcriptional promoting property of DmpR by constraining ATP-mediated changes in its oligomeric state. The results are discussed in the light of recent mechanistic insights from the AAA(+) superfamily of ATPases that utilise nucleotide hydrolysis to restructure their substrates.

Store-operated channels mediate Ca(2+) influx and contraction in rat pulmonary artery

Cation channels activated by Ca(2+) store depletion have been proposed to mediate Ca(2+) influx in vascular smooth muscle cells. The aim of this study was to determine if store-operated channels have a functional role in pulmonary artery smooth muscle cells (PASMCs). In intact rat pulmonary artery rings, cyclopiazonic acid (CPA) produced a sustained contraction that was resistant to inhibition by nifedipine, but abolished in Ca(2+)-free solution and 50% blocked in the presence of 6 micromol/L Cd(2+), 10 micromol/L Ni(2+), 600 micromol/L La(3+), and 7 micromol/L SKF96365. In freshly isolated PASMCs loaded with fura-2, CPA increased the intracellular Ca(2+) concentration by stimulating dihydropyridine-resistant Ca(2+) influx, which was approximately 50% blocked by 10 micromol/L Ni(2+) and 7 micromol/L SKF96365. In perforated-patch recordings, CPA activated a sustained inward current at negative membrane potentials, which persisted in cells dialyzed with BAPTA, showed a near linear dependence on membrane potential when Cs(+) was the main intracellular cation, and was blocked by Ni(2+), Cd(2+), and SKF96365 at concentrations preventing contraction. The current showed a bimodal dependence on extracellular Ca(2+), being enhanced 2-fold in the absence of Ca(2+) and around 10-fold on reducing Ca from 1.8 to 0.2 mmol/L. RT-PCR revealed the expression of Trp1, Trp3, Trp4, Trp5, and Trp6 mRNA, whereas immunostaining identified Trp1, Trp3, Trp4, and Trp6 channel proteins in isolated PASMCs. At least one of these subunits may contribute to cation channels in PASMCs, which are activated by store depletion to bring about Ca(2+) influx and contraction.

Microalbuminuria measurements by two in-house ELISA methods

Detection of microalbuminuria is important in the management of diabetic patients since it is predictive of development of proteinuria and nephropathy. Two sensitive and specific in-house ELISAs for microalbuminuria were established and validated. One of the ELISAs was based on antigen coating while the other employed antibody coating. Recovery and linearity experiments gave acceptable results of 100 +/- 10%, while precision results were <10% for intra-assay and <12% for inter-assay coefficients of variation (CVs). The standard curve ranged from 10-625 ug/l, equivalent to 0.2-12.5 mg/l for urine samples diluted 1:20 fold. When the antibody coated ELISA was compared to antigen coated ELISA, a correlation of r=0.996 was obtained. When compared to commercial kits, the in-house ELISAs gave good correlations of r=0.961 versus the Boehringer Mannheim Micral Test strips and r=0.940 versus Ames Microalb Turbidimetry. The normal microalbumin reference ranges determined for 12h, first morning and random urine samples were 0.7-5.3 mg, 0.1-10.2 mg/l and 0.8-26.1 mg/l respectively. The normal albumin excretion rate (AER) was 1.0-7.3 ug/min while untimed urine samples gave results of 0.1-0.9 and 0.2-1.6 mg/mmol after dividing by creatinine concentrations. The ELISAs were used to detect microalbuminuria in 338 random urine samples from diabetic patients. A high percentage 47.9% was found to be positive for microalbuminuria and 18.0% had macroalbuminuria >25 mg/mmol. Thus screening for microalbuminuria together with creatinine measurements using random urine samples can be used for management of diabetic patients.

Comparison between electroglottography and electromagnetic glottography

Newly developed glottographic sensors, utilizing high-frequency propagating electromagnetic waves, were compared to a well-established electroglottographic device. The comparison was made on four male subjects under different phonation conditions, including three levels of vocal fold adduction (normal, breathy, and pressed), three different registers (falsetto, chest, and fry), and two different pitches. Agreement between the sensors was always found for the glottal closure event, but for the general wave shape the agreement was better for falsetto and breathy voice than for pressed voice and vocal fry. Differences are attributed to the field patterns of the devices. Whereas the electroglottographic device can operate only in a conduction mode, the electromagnetic device can operate in either the forward scattering (diffraction) mode or in the backward scattering (reflection) mode. Results of our tests favor the diffraction mode because a more favorable angle imposed on receiving the scattered (reflected) signal did not improve the signal strength. Several observations are made on the uses of the electromagnetic sensors for operation without skin contact and possibly in an array configuration for improved spatial resolution within the glottis.

Aromatic ligand binding and intramolecular signalling of the phenol-responsive sigma54-dependent regulator DmpR

The Pseudomonas-derived sigma54-dependent regulator DmpR has an amino-terminal A-domain controlling the specificity of activation by aromatic effectors, a central C-domain mediating an ATPase activity essential for transcriptional activation and a carboxy-terminal D-domain involved in DNA binding. In the presence of aromatic effectors, the DmpR protein promotes transcription from the -24, -12 Po promoter controlling the expression of specialized (methyl)phenol catabolic enzymes. Previous analysis of DmpR has led to a model in which the A-domain acts as an interdomain repressor of DmpR's ATPase and transcriptional promoting property until specific aromatic effectors are bound. Here, the autonomous nature of the A-domain in exerting its biological functions has been dissected by expressing portions of DmpR as independent polypeptides. The A-domain of DmpR is shown to be both necessary and sufficient to bind phenol. Analysis of phenol binding suggests one binding site per monomer of DmpR, with a dissociation constant of 16 microM. The A-domain is also shown to have specific affinity for the C-domain and to repress the C-domain mediated ATPase activity in vitro autonomously. However, physical uncoupling of the A-domain from the remainder of the regulator results in a system that does not respond to aromatics by its normal derepression mechanism. The mechanistic implications of aromatic non-responsiveness of autonomously expressed A-domain, despite its demonstrated ability to bind phenol, are discussed.

Speech articulator measurements using low power EM-wave sensors

Very low power electromagnetic (EM) wave sensors are being used to measure speech articulator motions as speech is produced. Glottal tissue oscillations, jaw, tongue, soft palate, and other organs have been measured. Previously, microwave imaging (e.g., using radar sensors) appears not to have been considered for such monitoring. Glottal tissue movements detected by radar sensors correlate well with those obtained by established laboratory techniques, and have used to estimate a voiced excitation function for speech processing applications. The noninvasive access, coupled with the small size, low power, and high resolution of these new sensors, permit promising research and development applications in speech production, communication disorders, speech recognition and related topics.

Insulin treatment normalizes reduced free insulin-like growth factor-I concentrations in diabetic children

OBJECTIVE

We have recently demonstrated multiple aberrations in the GH-IGF axis in the sera of children with untreated insulin-dependent diabetes mellitus (IDDM) which were restored after insulin replacement. However, the net result of these alterations in the IGF system on the concentrations of free/biologically available IGF-I in the serum have not been examined directly in diabetic children. In the present study, the effect of diabetes and subsequent insulin replacement on the circulating free IGF-I concentrations are assessed.

DESIGN

Fasting venous serum samples were obtained longitudinally, before and at various times after the initiation of insulin treatment in untreated diabetic subjects.

SUBJECTS

Ten prepubertal, aged (mean +/- SEM) 6.3 +/- 1.0 years, and six adolescent, aged 12.7 +/- 1.1 years, subjects with newly diagnosed and untreated IDDM, and age and pubertal status-matched control children and adolescents were recruited.

METHODS

The serum samples were collected before initiating insulin treatment and 12-24 h, 1 week, and 1 month thereafter in subjects with IDDM. Insulin doses ranged from 0.5 to 1.2 U/kg/day.

MEASUREMENTS

Free IGF-I concentration was assayed by a recently developed two-site immunoradiometric assay. Total IGF-I was measured by radioimmunoassay after acid-ethanol extraction of binding proteins. Differences in free and total IGF-I concentrations in IDDM subjects before and during insulin treatment were analysed by repeated measures analysis of variance followed by pairwise multiple comparisons test. In seven subjects with IDDM, where serum IGFBP-1 and IGFBP-3 concentrations, and IGFBP-3 protease activity had also been measured in a previous study, the relationship between these variables and circulating free IGF-I concentrations were examined by linear regression analysis.

RESULTS

Free IGF-I concentrations in prepubertal subjects with IDDM were 0.9 +/- 0.2, 1.5 +/- 0.3, 1.6 +/- 0.3 and 2.5 +/- 0.4 micrograms/l before, 1 day, 1 week and 1 month after insulin treatment, respectively. Free IGF-I concentrations of control prepubertal children were 2.6 +/- 0.5 micrograms/l. Pubertal subjects had higher free IGF-I concentrations than prepubertal subjects but demonstrated a similar type of pattern; before insulin 2.3 +/- 1.1, 1 day 3.8 +/- 1.3, 1 week 3.7 +/- 0.6, 1 month 6.5 +/- 1.5 vs pubertal controls 7.7 +/- 2.0 micrograms/l. Total IGF-I concentrations were also reduced in untreated diabetic subjects and showed a slower pattern of normalization than free IGF-I concentrations. Free IGF-I concentrations correlated positively with total IGF-I and negatively with IGFBP-1 concentrations. There was no significant correlation between free IGF-I and either serum IGFBP-3 concentrations or IGFBP-3 protease activity.

CONCLUSION

Alterations in the IGF system during untreated IDDM lead to a reduction in circulating free IGF-I concentrations which is restored progressively during insulin treatment. An increase in free IGF-I precedes that of total IGF-I suggesting that the former is a more sensitive indicator of the metabolic status. An inverse correlation between free IGF-I and IGFBP-1 supports the hypothesis that IGFBP-1 plays an important role in the acute modulation of free IGF-I levels.

Genetic evidence for interdomain regulation of the phenol-responsive final sigma54-dependent activator DmpR

The final sigma54-dependent DmpR activator regulates transcription of the dmp operon that encodes the enzymes for catabolism of (methyl)phenols. DmpR is expressed constitutively, but its transcriptional promoting activity is controlled positively in direct response to the presence of aromatic pathway substrates (effectors). DmpR has a distinct domain structure with the amino-terminal A-domain controlling the specificity of activation of the regulator by aromatic effectors (signal reception), a central C-domain mediating an ATPase activity essential for transcriptional activation, and a carboxyl-terminal D-domain involved in DNA binding. Deletion of the A-domain has been shown previously to result in an effector-independent transcriptional activator with constitutive ATPase activity. These results, in conjunction with the location of mutations within the A- and C-domains which exhibit an effector-independent (semiconstitutive) property, have led to a working model in which the A-domain serves to mask the ATPase and transcriptional promoting activity of the C-domain in the absence of effectors. To investigate the mechanism by which the A-domain exerts its repressive effect, we developed a genetic system to select positively for intramolecular second site revertants of DmpR. The results demonstrate (i) that mutations within the A-domain can suppress the semiconstitutive activity of C-domain located mutations and vice versa; (ii) that the C-domain located mutations do not influence the intrinsic ATPase and transcriptional promoting property of the C-domain in the absence of the A-domain; and (iii) that semiconstitutive mutations of the A- and C-domain have an additive effect. Taken together these results support a model in which the A-domain represses the function(s) of the C-domain by direct interactions between residues of the two domains.

Aromatic effector activation of the NtrC-like transcriptional regulator PhhR limits the catabolic potential of the (methyl)phenol degradative pathway it controls

Pseudomonas putida P35X (NCIB 9869) metabolizes phenol and monomethylphenols via a chromosomally encoded meta-cleavage pathway. We have recently described a 13.4-kb fragment of the chromosome that codes for the first eight genes of the catabolic pathway and a divergently transcribed positive regulator, phhR. The eight structural genes lie in an operon, the phh operon, downstream of a -24 TGGC, -12 TTGC promoter sequence. Promoters of this class are recognized by RNA polymerase that utilizes the alternative sigma 54 factor encoded by rpoN (ntrA) and are positively regulated by activators of the NtrC family. In this study, we have identified the coding region for the 63-kDa PhhR gene product by nucleotide sequencing of a 2,040-bp region and polypeptide analysis. PhhR was found to have homology with the NtrC family of transcriptional activators, in particular with DmpR, the pVI150-encoded regulator of (methyl)phenol catabolism by Pseudomonas sp. strain CF600. By using a luciferase reporter system, PhhR alone was shown to be sufficient to activate transcription from the phh operon promoter in an RpoN+ background but not an RpoN- background. Luciferase reporter systems were also used to directly compare the aromatic effector profiles of PhhR and DmpR. Evidence that the difference in the growth substrate ranges of strains P35X and CF600 is due to the effector activation specificities of the regulators of these systems rather than the substrate specificities of the catabolic enzymes is presented.

Cloning and sequences of the first eight genes of the chromosomally encoded (methyl) phenol degradation pathway from Pseudomonas putida P35X

Pseudomonas putida P35X (NCIB 9869) metabolises phenol and cresols via a chromosomally encoded meta-cleavage pathway. A 13.4-kb fragment of the chromosome involved in encoding phenol catabolism was cloned and characterized. Deletion analysis and nucleotide sequencing of a 6589-bp region, in conjunction with enzyme assays, were used to identify the phhKLMNOP genes encoding the phenol hydroxylase, the phhB gene encoding catechol 2,3-dioxygenase (EC 1.13.11.2) and the phhQ gene that encodes a small ferredoxin-like protein. The genes are organised in an operon-like structure, in the order phhKLMNOPQB, and the deduced amino-acid sequences share high homology (68.3-99.7%) with those of the plasmid-encoded genes dmpKLMNOPQB of Pseudomonas sp. strain CF600. Genetic evidence is presented that the difference in the growth substrate ranges of Pseudomonas P35X and CF600 are due to the effector activation specificities of the regulators of these systems, rather than the substrate specificities of the catabolic enzymes.

Quantitative comparison of prolactin production by decidua compacta and spongiosa from the first trimester elective termination of pregnancy

Prolactin (PRL) producing capacity was studied in explants of decidua compacta and decidua spongiosa obtained from 41 patients undergoing termination of pregnancy at gestation 6 to 12 weeks. In vitro PRL producing capacity, expressed as mIU/g protein, of the decidua compacta was significantly higher (P < 0.05) than those of decidua spongiosa. Production of PRL increased with gestation from 6 to 12 weeks with a more rapid rate at the later gestation. The pattern of increase fitted significantly (P < 0.0001) to the exponential model for both decidua compacta and decidua spongiosa. The exponential regression equations for decidua compacta and decidua spongiosa were (ln y = 4.25 + 0.19x) and (ln y = 2.80 + 0.31x) respectively. Hence, although both decidua compacta and decidua spongiosa had a similar pattern of increase in PRL production, the rate of increment was significantly greater in decidua spongiosa than in decidua compacta. These findings suggest that separating decidua compacta and decidua spongiosa of the first trimester would reduce the heterogeneity of decidual tissue and offer a new approach to the studies of the synthesis, release and regulation of PRL production by human decidua.