Neonatal AKI: An update

Neonatal acute kidney injury (AKI) is a common complication, especially in the neonatal intensive care unit, that is associated with long term consequences and poor outcomes. Early detection and treatment is critical. Currently, neonatal AKI is defined with urinary markers and serum creatinine, with limitations on early detection and individual treatment. There have been numerous biomarkers and risk factor scores that have been studied for their ability to predict neonatal AKI. To move towards personalized medicine, neonatal AKI must be categorized into phenotypes and subphenotypes that fully encapsulate the diverse causes and specific treatments. This review aims to advance our understanding of neonatal AKI detection through the use of biomarkers, subphenotypes, and phenotypes to move towards personalized treatment strategies.

Quantifying Brain Iron in Hereditary Hemochromatosis Using R2* and Susceptibility Mapping

BACKGROUND AND PURPOSE

Brain iron dyshomeostasis is increasingly recognized as an important contributor to neurodegeneration. Hereditary hemochromatosis is the most commonly inherited disorder of systemic iron overload. Although there is an increasing interest in excessive brain iron deposition, there is a paucity of evidence showing changes in brain iron exceeding that in healthy controls. Quantitative susceptibility mapping and R2* mapping are established MR imaging techniques that we used to noninvasively quantify brain iron in subjects with hereditary hemochromatosis.

MATERIALS AND METHODS

Fifty-two patients with hereditary hemochromatosis and 47 age- and sex-matched healthy controls were imaged using a multiecho gradient-echo sequence at 3T. Quantitative susceptibility mapping and R2* data were generated, and regions within the deep gray matter were manually segmented. Mean susceptibility and R2* relaxation rates were calculated for each region, and iron content was compared between the groups.

RESULTS

We noted elevated iron levels in patients with hereditary hemochromatosis compared with healthy controls using both R2* and QSM methods in the caudate nucleus, putamen, pulvinar thalamus, red nucleus, and dentate nucleus. Additionally, the substantia nigra showed increased susceptibility while the thalamus showed an increased R2* relaxation rate compared with healthy controls, respectively.

CONCLUSIONS

Both quantitative susceptibility mapping and R2* showed abnormal levels of brain iron in subjects with hereditary hemochromatosis compared with controls. Quantitative susceptibility mapping and R2* can be acquired in a single MR imaging sequence and are complementary in quantifying deep gray matter iron.

HLA Desensitization Based on Results of the Luminex Technique in Kidney Transplant - A Single-center Experience

Background:

There is little experience of human leucocyte antigen (HLA) desensitization in India based on the Luminex single-antigen bead (SAB) testing. We retrospectively analyzed our patients, who underwent HLA desensitization based on Luminex SAB results.

Method:

Between 2014 and 2018, patients with complement-dependent cytotoxicity cross-match (CDC-XM) negativity but flow cytometry crossmatch (FC-XM) positivity were further analyzed with Luminex SAB for donor-specific antibodies (DSAs). A total of 12 patients who had DSA mean fluorescent intensity (MFI) of >1000 and <10,000 were included in the study. Our protocol for desensitization consisted of plasmapheresis (PP) followed by low dose intravenous immunoglobulin (IV IG) 100 mg/kg and induction with antithymocyte globulin (ATG). Patients were taken for transplant when either MFI was <1000 and/or FC-XM was negative.

Results:

All 12 patients were first transplant and 10 had a history of some sensitizing event; pregnancy in 4, blood transfusions in 4, and both in 2 patients. FC-XM was positive for T-cell in 4, B-cell in 6, and both in 2 patients. On evaluation by Luminex SAB, 6 patients had MFI from 1000 to 2000, and 6 had MFI of >2000. All underwent desensitization successfully. Two patients had an increase in posttransplant DSA titers requiring posttransplant PP. The mean follow-up was 26.6 ± 13.9 months. On follow-up, only one patient developed acute T cell-mediated rejection 1 year after transplant, which responded to pulse steroids. There was no graft or patient loss until the last follow-up.

Conclusion:

This study shows that HLA desensitization is feasible and successful in the Indian setting if patients are properly selected.

Clinical evaluation of serological IgG antibody response on the Abbott Architect for established SARS-CoV-2 infection

OBJECTIVE

This study aimed to evaluate the diagnostic performance of the Abbott Architect SARS-CoV-2 IgG assay in COVID-19 patients.

METHODS

Residual sera from 177 symptomatic SARS-CoV-2-positive patients and 163 non-COVID-19 patients were tested for antibody with the Abbott SARS-CoV-2 IgG assay (Abbott Diagnostics, Chicago, USA). Clinical records for COVID-19 patients were reviewed to determine the time from onset of clinical illness to testing.

RESULTS

Specificity of the assay was 100.0% (95%CI: 97.1-100.0%). The clinical sensitivity of the assay varied depending on time from onset of symptoms, increasing with longer periods from the onset of clinical illness. The clinical sensitivity at ≤6 days was 8.6% (7/81; 95%CI: 3.8-17.5%), at 7-13 days 43.6% (17/39; 95%CI: 28.2-60.2%), at 14-20 days 84.0% (21/25; 95%CI: 63.1-94.7%), and at ≥21 days 84.4% (27/32; 95%CI: 66.5-94.1%). Clinical sensitivity was higher in the ≥14-day group compared to <14 days. There were no differences between the 14-20-day and ≥21-days groups; the combined clinical sensitivity for these groups (≥14 days) was 84.2% (49/57; 71.6-92.1%).

CONCLUSION

The Abbott SARS-CoV-2 IgG test has high specificity. Clinical sensitivity was limited in the early stages of disease but improved from 14 days after the onset of clinical symptoms.

Jugular Anomalies in Multiple Sclerosis Are Associated with Increased Collateral Venous Flow

BACKGROUND AND PURPOSE

To date, research on extracranial venous collaterals has been focused on structure, with relatively little attention paid to hemodynamics. We addressed this limitation by quantitatively comparing collateral flow in patients with multiple sclerosis and healthy controls by using phase-contrast MR imaging. We hypothesize that patients with MS with structurally anomalous internal jugular veins will have elevated collateral venous flow compared with healthy controls.

MATERIALS AND METHODS

The sample consisted of 276 patients with MS and 106 healthy controls. We used MRV to classify internal jugular veins as stenotic and nonstenotic based on an absolute cross-sectional area threshold in 276 patients with MS and 60 healthy controls; 46 healthy controls lacked this imaging. Individual and total vessel flows were quantified by using phase-contrast MR imaging on all patients. Veins were classified by extracranial drainage type: internal jugular veins (I), paraspinal (II), and superficial (III). Differences among healthy controls, patients with MS, nonstenotic patients, and stenotic subgroups in total venous flow by vessel type were evaluated in a general linear model for statistical analysis.

RESULTS

In the MS group, 153 patients (55%) evidenced stenosis, whereas 12 (20%) healthy controls were classified as stenotic (P < .001). Compared with healthy controls, the MS group showed lower type I flow and increased type II flow. Stenosis was associated with reduced flow in the type I vessels [F(1272) = 68; P < .001]. The stenotic MS group had increased flow in the type II vessels compared with the nonstenotic MS group [F(1272) = 67; P < .001].

CONCLUSIONS

Compared with healthy controls, patients with MS exhibit reduced venous flow in the main extracerebral drainage vein (internal jugular vein). In contrast, flow in the paraspinal venous collaterals is elevated in patients with MS and exacerbated by venous stenosis. Collateral drainage may be a compensatory response to internal jugular vein flow reduction.

Remission of post-transplant focal segmental glomerulosclerosis with angiotensin receptor blockers

Recurrence of focal segmental glomerulosclerosis (FSGS) is common after kidney transplantation. Plasmapheresis (PP) is considered to be the most effective treatment; however, results are variable and relapse is common after stopping plasmapheresis. Here, we report an unusual case of recurrent FSGS, who achieved complete remission with angiotensin receptor blocker therapy.

Targeting renin-angiotensin system in malignant hypertension in atypical hemolytic uremic syndrome

Hypertension is common in hemolytic uremic syndrome (HUS) and often difficult to control. Local renin-angiotensin activation is believed to be an important part of thrombotic microangiopathy, leading to a vicious cycle of progressive renal injury and intractable hypertension. This has been demonstrated in vitro via enhanced tissue factor expression on glomerular endothelial cells which is enhanced by angiotensin II. We report two pediatric cases of atypical HUS with severe refractory malignant hypertension, in which we targeted the renin-angiotensin system by using intravenous (IV) enalaprilat, oral aliskiren, and oral enalapril with quick and dramatic response of blood pressure. Both drugs, aliskiren and IV enalaprilat, were effective in controlling hypertension refractory to multiple antihypertensive medications. These appear to be promising alternatives in the treatment of severe atypical HUS-induced hypertension and hypertensive emergency.

Eculizumab for atypical hemolytic-uremic syndrome in India: First report from India and the challenges faced

Much progress has been made in understanding the pathophysiology and treatment of atypical hemolytic uremic syndrome (aHUS). Plasma therapy is the mainstay of treatment for aHUS. The availability of the first effective anti-complement therapeutic agent, eculizumab, has dramatically changed the outlook of this disease. However, its use in clinical practice raises important questions, such as who should receive the drug, when to start such therapy, and is it safe to stop treatment once the disease is controlled. We describe here for the 1^st time in India, use of eculizumab in a 12-year-old boy with aHUS. We also describe in this report challenges faced in procuring the drug, and an ideal, evidence-based method of treating aHUS in children.

Validation of a Hemodynamic Model for the Study of the Cerebral Venous Outflow System Using MR Imaging and Echo-Color Doppler Data

BACKGROUND AND PURPOSE

A comprehensive parameter model was developed to investigate correlations between cerebral hemodynamics and alterations in the extracranial venous circulation due to posture changes and/or extracranial venous obstruction (stenosis). The purpose of this work was to validate the simulation results by using MR imaging and echo-color Doppler experimental blood flow data in humans.

MATERIALS AND METHODS

To validate the model outcomes, we used supine average arterial and venous extracerebral blood flow, obtained by using phase-contrast MR imaging from 49 individuals with stenosis in the acquisition plane at the level of the disc between the second and third vertebrae of the left internal jugular vein, 20 with stenosis in the acquisition plane at the level of the disc between the fifth and sixth vertebrae of the right internal jugular vein, and 38 healthy controls without stenosis. Average data from a second group of 10 healthy volunteers screened with an echo-color Doppler technique were used to evaluate flow variations due to posture change.

RESULTS

There was excellent agreement between experimental and simulated supine flows. Every simulated CBF fell inside the standard error from the corresponding average experimental value, as well as most of the simulated extracerebral arterial flow (extracranial blood flow from the head and face, measured at the level of the disc between second and third vertebrae) and venous flows. Simulations of average jugular and vertebral blood flow variations due to a change of posture from supine to upright also matched the experimental data.

CONCLUSIONS

The good agreement between simulated and experimental results means that the model can correctly reproduce the main factors affecting the extracranial circulation and could be used to study other types of stenotic conditions not represented by the experimental data.

ABO-incompatible renal transplantation in developing world - crossing the immunological (and mental) barrier

ABO incompatibility has been considered as an important immunological barrier for renal transplantation. With the advent of effective preconditioning protocols, it is now possible to do renal transplants across ABO barrier. We hereby present a single center retrospective analysis of all consecutive ABOi renal transplants performed from November 2011 to August 2014. Preconditioning protocol consisted of rituximab, plasmapheresis and intravenous immunoglobulin (IVIG) and maintenance immunosuppression consisted of tacrolimus, mycophenolate sodium, and prednisolone. The outcome of these ABOi transplants was compared with all other consecutive ABO-compatible (ABOc) renal transplants performed during same time. Twenty ABOi renal transplants were performed during the study period. Anti-blood group antibody titer varied from 1:2 to 1:512. Patient and graft survival was comparable between ABOi and ABOc groups. Biopsy proven acute rejection rate was 15% in ABOi group, which was similar to ABOc group (16.29%). There were no antibody-mediated rejections in ABOi group. The infection rate was also comparable. We conclude that the short-term outcome of ABOi and ABOc transplants is comparable. ABOi transplants should be promoted in developing countries to expand the donor pool.

A simulation model to study the role of the extracranial venous drainage pathways in intracranial hemodynamics

Alterations in the extracranial venous circulation due to posture changes, and/or extracranial venous obstructions in patients with vascular diseases, can have important implications on cerebral hemodynamics. A hemodynamic model for the study of cerebral venous outflow was developed to investigate the correlations between extracranial blood redistributions and changes in the intracranial environment. Flow data obtained with both magnetic resonance (MR) and Echo-Color Doppler (ECD) technique are used to validate the model. The very good agreement between simulated supine and upright flows and experimental results means that the model can correctly reproduce the main factors affecting the extracranial venous circulation.

Effect of fly ash application on soil microbial response and heavy metal accumulation in soil and rice plant

Fly ash (FA), a byproduct of coal combustion in thermal power plants, has been considered as a problematic solid waste and its safe disposal is a cause of concern. Several studies proposed that FA can be used as a soil additive; however its effect on microbial response, soil enzymatic activities and heavy metal accumulation in soil and grain of rice (cv. Naveen) to fly ash (FA) application was studied in a pot experiment during dry season 2011 in an Inceptisol. Fly ash was applied at a rate of zero per cent (FS), five per cent (FA5), ten per cent (FA10), twenty per cent (FA20), 40 per cent (FA40) and 100 per cent (FA100) on soil volume basis with nitrogen (N), phosphorus (P) and potassium (K) (40:20:20mg N:P:Kkg(-1) soil) with six replications. Heavy metals contents in soil and plant parts were analysed after harvest of crop. On the other hand, microbial population and soil enzymatic activities were analysed at panicle initiation stage (PI, 65 days after transplanting) of rice. There was no significant change in the concentration of zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), cadmium (Cd) and chromium (Cr) with application of fly ash up to FA10. However, at FA100 there was significant increase of all metals concentration in soil than other treatments. Microorganisms differed in their response to the rate of FA application. Population of both fungi and actinomycetes decreased with the application of fly ash, while aerobic heterotrophic bacterial population did not change significantly up to FA40. On the other hand, total microbial activity measured in terms of Fluorescein diacetate (FDA) assay, and denitrifiers showed an increased trend up to FA40. However, activities of both alkaline and acid phosphatase were decreased with the application of FA. Application of FA at lower levels (ten to twenty per cent on soil volume basis) in soil enhanced micronutrients content, microbial activities and crop yield.

Methemoglobinemia due to quinine causing severe acute kidney injury in a child

Congenital methemoglobinemia is a rare condition resulting from a deficiency of nicotinamide adenine dinucleotide-cytochrome b5 reductase. Acquired methemoglobinemia may result due to certain drugs, chemicals and food items. Information on epidemiological determinants from India is sparse. This report describes methemoglobinemia in a 4-year-old child after parenteral administration of quinine causing acute kidney injury. This case emphasizes the need of awareness of potential adverse events of antimalarial drugs. Prompt management of methemoglobinemia is essential to avoid potential life-threatening complications.

Renal transplantation across ABO barrier

In India, patients without a compatible blood group donor are usually excluded from renal transplantation. For young patients, it is a difficult therapeutic choice to stay on long-term dialysis. We describe the case of a 19-year-old male patient who had blood group O +ve and had no compatible donor in the family. His mother was B +ve and was willing to donate. The patient had an initial anti-B antibody titer of 1:512 and underwent antibody depletion with plasmapheresis (11 sessions) and intravenous immunoglobulin (IVIG) 100 mg/kg after every plasmapheresis. He also received rituximab 500 mg for 3 days prior to transplant and was induced with basiliximab. At the time of transplant, his anti-B titers were <1:8. Post-operatively, he required four sessions of plasmapheresis and IVIG as his titers rebounded to 1:64. The titers then spontaneously subsided to <1:16 and have stayed at the same level for 6 months post-transplant. The patient continues to have normal renal function with a creatinine of 1.4 mg/dl% and has had no episodes of rejection.

Giant cell transformation of podocytes: A unique histological feature associated with cystinosis

Fanconi's syndrome is an unusual cause of renal insufficiency in pediatric patients. Infantile cystinosis is one of the identifiable and treatable etiologies of Fanconi's syndrome. Early diagnosis of cystinosis permits institution of specific therapy with cysteamine. A 3-year-old girl presented with failure to thrive, polyuria, and polydipsia. She was found to have renal tubular defect with renal dysfunction and bilateral small contracted kidneys. A renal biopsy revealed extensive giant cell transformation of podocytes in the glomeruli with focal tubular atrophy and dilatation. However, no crystals were identified. Subsequent ophthalmoscopic examination revealed fine cystine crystals in the cornea and a diagnosis of cystinosis causing Fanconi's syndrome was made. Polykaryocytic transformation of visceral epithelial cells is an important diagnostic clue of nephropathic cystinosis and should be carefully looked for in renal biopsy from a child with Fanconi's syndrome and renal insufficiency.

Ministry of health clinical practice guidelines: screening of cardiovascular disease and risk factors

The Ministry of Health (MOH) publishes clinical practice guidelines on Screening of Cardiovascular Disease and Risk Factors to provide doctors and patients in Singapore with evidence-based guidance on the screening of cardiovascular disease and risk factors. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Screening of Cardiovascular Disease and Risk Factors, for the information of readers of the Singapore Medical Journal. 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=25776). 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.

Elderly woman with cerebrovascular accident and refractory arrhythmias

Fatal bilateral cerebro-vascular accident with variable atrio-ventricular blocks, atrial fibrillation and refractory tachy-arrhythmias in a previously healthy 75-years-old hypertensive female is presented.

Vibrio cholerae diarrhoea in a three-day-old breastfed neonate

A confirmed case of cholera in a 3-day-old neonate is being reported. Possible source of infection could be by holy water (Chamamrit) given to the baby, which is common ritual in India. Mother's milk has never been reported to transmit cholera, even though mother herself may be suffering from cholera. Contaminated water can transmit the disease as there is no maternally transmitted immunity.

Compound heterozygous familial hypercholesterolemia and familial defective apolipoprotein B-100 produce exaggerated hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) represent ligand-receptor disorders that are complementary. Individuals with both FH and FDB are unusual. We report a family with both disorders and the impact of the mutations on the phenotypes of the family members.

METHODS

We used single strand conformation polymorphism (SSCP) and denaturing gradient gel electrophoresis (DGGE) for genetic analysis of all 18 exons and the promoter region of the LDL receptor and DGGE for genetic analysis of the apolipoprotein B-100 (apo B-100) gene. The functional significance of the apo B-100 mutation was studied using a U937 cell proliferation assay. Fasting serum lipid profiles were determined for the index case and seven first-degree relatives.

RESULTS

One of the patient's sisters had a missense mutation (Asp(407)-->Lys) in exon 9 of the LDL receptor and a serum LDL-cholesterol concentration of 4.07 mmol/L. Four other first-degree relatives had hyperlipidemia but no LDL-receptor mutation. However, these subjects had a mutation of the apo B-100 gene (Arg(3500)-->Trp). The cell proliferation rate of U937 cells fed with LDL from other subjects with the same mutation was fourfold less than that of controls. The index case had both FH- and FDB-related mutations. Her serum LDL-cholesterol (9.47 mmol/L) was higher than all other relatives tested.

CONCLUSIONS

Existence of both FH and FDB should be considered in families with LDL-receptor mutations in some but not all individuals with hypercholesterolemia or when some individuals in families with FH exhibit exaggerated hypercholesterolemia.

Rhinocerebral mucormycosis in a patient of acute renal failure

Mucormycosis is the name for invasive fungal infection caused by mucorales. The disease is uncommon and produces serious and rapidly fatal infection in patients with serious pre-existing illness. The classical presentation of rhinocerebral mucormycosis is involvement of nasal mucosa with invasion of paranasal sinuses and orbit. We report a case of mucormycosis in an otherwise healthy female who had developed acute renal failure following gastroenteritis.

Expression of intercellular adhesion molecule-1 (ICAM-1) in nasal epithelial cells of atopic subjects: a mechanism for increased rhinovirus infection?

Since clinical experimental studies indicate that upper respiratory tract viral infections may exacerbate acute asthma symptoms in atopic/asthmatic individuals, we have investigated the expression and modulation of ICAM-1 on human nasal epithelial cells (HNEC) from normal and atopic subjects. ICAM-1 is the attachment molecule for the majority of serotypes of human rhinovirus (HRV), including HRV-14, and is also critical for the migration and activation of immune effector cells. Basal ICAM-1 expression was significantly higher in HNEC obtained by brushings from atopic compared with non-atopic subjects (P = 0.031), and was also significantly increased on atopic HNEC harvested in season compared with out of season (P < 0.05). Atopic HNEC showed further up-regulation in ICAM-1 expression when cultured with clinically relevant allergen (P = 0.032). ICAM-1 levels on normal HNEC were also increased by infection with HRV-14 (P < 0.05). Basal expression of ICAM-1 on atopic nasal polyp epithelial cells (EC) was significantly higher than on both normal and atopic nasal HNEC. This elevated nasal polyp ICAM-1 level was not increased further by allergen, although HRV infection resulted in a small significant increase. Recovered viral titres from HRV-infected nasal polyp EC were 1.5-fold higher than from infected normal nasal HNEC. The data are consistent with the hypothesis that allergen, by enhancing expression of the HRV attachment target on host cells, facilitates viral infection in atopic subjects; simultaneously HRV-induced increases in ICAM-1 levels would favour migration and activation of immune effector cells to the airway, resulting in enhanced atopic inflammation.

Effects of intragenic variability at 3 polymorphic sites of the apolipoprotein B gene on serum lipids and lipoproteins in a multiethnic Asian population

We determined the allelic (X+/X-, M+/M-, and E+/E-) distribution frequencies of the XbaI, MspI, and EcoRI restriction fragment length polymorphisms (RFLPs) in the apolipoprotein B gene in a control group of 374 healthy Chinese, Malays, and Indians and in a hyperlipidemic cohort of 131 Chinese patients. Covariability between the RFLPs and serum lipid, lipoprotein, and apolipoprotein concentrations was also studied. We found a lower frequency (average 0.0829) of the X+ allele and higher frequencies of the E+ (average 0.9452) and M+ (average 0.9772) alleles in our study population compared with frequencies reported in other populations. The 3 polymorphic sites did not contribute to significant variations in lipid levels (p > 0.1 in all cases). Also, there was no significant variation in genotype frequencies between the control subjects and the hyperlipidemic subjects. Despite their relative close proximity within the APOB gene sequence, the 3 polymorphic sites did not show any significant linkage disequilibrium. However, the presence of the X+ cutting site was in linkage disequilibrium with the Del allele of the 5' insertion-deletion polymorphism and the E-allele was in linkage disequilibrium with the 3' VNTR located near the 3' end of the coding region of the APOB gene.

Th2 cytokines exert a dominant influence on epithelial cell expression of the major group human rhinovirus receptor, ICAM-1

Intercellular adhesion molecule (ICAM)-1 is a cell receptor important in both human rhinovirus (HRV) attachment and immune effector cell mobilization. The level of expression of ICAM-1 by epithelial cells (EC) therefore plays a crucial role in the intricate biological phenomena underlying viral binding, host infection and consequent inflammatory events. As T-helper (Th)2 lymphocytes predominate within the asthmatic airway, the influence was evaluated of Th2-associated mediators in the modulation of ICAM-1 expression on uninfected and HRV-infected EC. H292 EC were cultured in vitro, with varying concentrations of interleukin (IL)-4, IL-5, IL-10 and IL-13 for 24 h and then infected with live HRV-14. Surface ICAM-1 expression was assessed by immunocytochemistry. Infection with HRV-14 resulted in a twofold increase in ICAM-1 expression. IL-4, IL-5, IL-10 and IL-13 produced a 2.7-5.1-fold enhancement of ICAM-1 expression of uninfected cells and caused approximately a further twofold increase in infected cells over the expression induced by HRV infection itself. Interferon-gamma in combination with each Th2-associated cytokine only slightly reduced, but did not override, the Th2-induced level of ICAM-1 expression on both uninfected and virus-infected EC. These data suggest that the effects of Th2-associated cytokines on intercellular adhesion molecule-1 expression and recovery of infectious virus are dominant over the effects of the Th1-associated cytokines such as interferon-gamma. Since the airway mucosa in atopic asthma is predominantly infiltrated by Th2 lymphocytes, these results could explain both the increased susceptibility to human rhinovirus infection in asthmatic patients and the associated exacerbation of asthma symptoms.

The StuI polymorphism on exon 8 of the low density lipoprotein (LDL) receptor gene: prevalence and impact on serum lipid levels in an Asian cohort

A single nucleotide (A-->G) substitution in codon 370 (exon 8) of the low density lipoprotein (LDL) receptor gene results in loss of a StuI restriction site and an amino acid change (Ala370-->Thr) in the translated protein. This biallelic polymorphism has been associated with significant variations in plasma lipid concentrations in several Caucasian populations. We investigated its prevalence and impact on lipid metabolism in 539 Singaporeans of Chinese, Malay and Indian descent. The average frequency of 0.003 for the Thr370 allele and heterozygosity of 0.0056 were 10- to 20-fold lower than those reported in Caucasians (range 0.075 to 0.107). Distribution of the genotypes satisfied the Hardy-Weinberg equilibrium (chi 2 = 0.004, P = 0.948). We also found ethnic variation in the allele frequencies of Thr370 among the three races studied (0.009 in Indians, 0.007 in Malays, and 0.003 in Chinese). However, this needs to be confirmed with larger numbers. No significant correlation between genotype and serum concentrations of total cholesterol, triglyceride, high density lipoprotein (HDL)-cholesterol, LDL-cholesterol, lipoprotein(a), apolipoprotein A and apolipoprotein B was found in our study. This argues strongly against a major contribution or impact of this intragenic polymorphic locus on modulating the serum lipid profiles of the study subjects.

Interferon-gamma (IFN-gamma) down-regulates the rhinovirus-induced expression of intercellular adhesion molecule-1 (ICAM-1) on human airway epithelial cells

Human rhinoviruses (HRV) are a major cause of upper respiratory tract infections in man, and can exacerbate existing pulmonary disease. The major group of HRV attach to ICAM-1, which is expressed on nasal and bronchial epithelial cells. To study the influence of biological mediators on ICAM-1 expression, and consequently HRV attachment and infection, we compared the effects of various cytokines, alone and in combination, on ICAM-1 expression by an uninfected and HRV-infected bronchial epithelial cell line H292. Cytokines known to be released soon after viral infection, such as tumour necrosis factor-alpha (TNF-alpha), IL-1beta and the chemokine IL-8 increase ICAM-1 expression on uninfected cells. Epithelial cells infected with live HRV-14 displayed marked up-regulation of ICAM-1 compared with baseline. TNF-alpha further enhanced the HRV-induced increase in ICAM-1 expression on epithelial cells, peaking at day 4 after infection, whilst IL-8 exhibited a steady increase in ICAM-1 expression over 14 days. In contrast, IFN-gamma, a known Th1 antiviral lymphokine, whilst increasing the level of ICAM-1 on uninfected cells, induced a significant persistent down-regulation of ICAM-1 expression on HRV-infected epithelial cells. With combinations of TNF-alpha and IFN-gamma, ICAM-1 expression on HRV-infected cells was reduced to basal levels. The effects of IFN-gamma were paralleled by a reduction in viral titres. Our in vitro model has provided useful insights into the early pathogenic events of HRV infection at the level of the host cell-virus interaction. Our data confirm that biological mediators play a crucial role in the pathogenesis as well as the course of HRV infection which is modulated by the types, and time kinetics of inflammatory cytokines in the immediate microenvironment.

Denaturing gradient-gel electrophoresis screening of familial defective apolipoprotein B-100 in a mixed Asian cohort: two cases of arginine3500-->tryptophan mutation associated with a unique haplotype

The Arg-to-Trp substitution at codon 3500 in the apolipoprotein (apo) B-100 gene is established as a cause of familial defective apo B-100 (FDB), a functional mutation, resulting in reduced LDL receptor binding and manifest hypercholesterolemia. In a search for similar mutations in 163 Malaysians, we screened the putative receptor-binding region (codons 3456-3553) of the apo B-100 gene by PCR amplification and denaturing gradient-gel electrophoresis. Four single-base mutations were detected and confirmed by DNA sequencing. Two females, a Chinese and a Malay, had the same CGG3500-->TGG mutation, resulting in an Arg3500-to-Trp substitution. This is the second published report of such an independent mutation involving the same codon as the established Arg3500-to-Gln mutation. The two other mutations detected, CTT3517-->CTG and GCC3527-->GCT, resulted in degenerate codons with no amino acid substitutions. All four mutations were associated with a unique apo B haplotype, different from those found in Caucasian FDB patients but concurring with that previously reported for two other Asians with FDB.

Analysis of polycyclic aromatic hydrocarbons in metered dose inhaler drug formulations by isotope dilution gas chromatography/mass spectrometry

Organic compounds extracted into metered dose inhalers (MDIs) from the rubber components of the metering valve are of increasing interest in the development of these formulations. Polycyclic aromatic hydrocarbons (PAHs) are a class of extractable organic compounds whose source is the carbon black commonly used as a reinforcing agent in rubber. The analytical method for PAHs described in this report employs "cold filtration" to remove the suspended drug substance and excipients, and gas chromatography/mass spectrometry (GC/MS) for separation and detection of individual PAHs. After filtration, stable isotope labelled analogues of target PAHs are spiked into the drug product to act as internal standards, correcting for recovery (termed "isotope dilution GC/MS"). Validation of the method was accomplished with respect to linearity, precision, limit of detection/quantitation, selectivity and ruggedness. Application to a variety of MDI drug product formulations revealed that certain PAHs are present at the ng/inhaler level.

Use of an alkaline phosphatase-labeled synthetic oligonucleotide probe for detection of Campylobacter jejuni and Campylobacter coli

A commercially available synthetic nucleic acid probe (SNAP) conjugated to alkaline phosphatase was compared with standard culture techniques for detecting Campylobacter species. The SNAP was able to detect either 5 ng of C. jejuni DNA or 10(5) CFU of bacteria. The SNAP could also detect DNA extracted from 10(5) CFU in mock-infected stool samples. The SNAP detected C. jejuni and C. coli but showed no reactivity with C. laridis, C. fetus subsp. fetus, C. fetus subsp. venerealis, C. fennelliae, "C. upsaliensis," C. cinaedii, C. fecalis, C. hyointestinalis, C. mucosalis, or Helicobacter (Campylobacter) pylori. The SNAP also showed no cross-reactivity with other enteric pathogens. When applied to pure cultures, the SNAP detected 55 clinical isolates of C. jejuni and 11 clinical isolates of C. coli, with an accuracy of 100%. When applied directly to clinical specimens, the SNAP detected Campylobacter spp. in 19 of 23 culture-positive stool specimens (sensitivity, 82.6%; specificity, 100%). Pure cultures of the Campylobacter strains isolated from the four probe-negative, culture-positive stool specimens gave positive reactions with the SNAP. While the SNAP had excellent sensitivity and specificity for isolated bacterial colony isolates, the main limitation to the Campylobacter probe detection kit may be the sensitivity limit on direct detection of Campylobacter organisms in stools.

Microbial etiology of acute gastroenteritis in hospitalized children in Kuwait

During a period of 15 months 621 hospitalized children with acute gastroenteritis and 152 control children were investigated for etiologic agents of the disease. Putative enteropathogens were identified in 86% of the patients and 10% of the controls. Common viral agents associated with gastroenteritis among children included rotaviruses (45%) and enteric adenoviruses (4%). Bacterial pathogens infecting children were Salmonella serotypes (24%), enterotoxigenic Escherichia coli (9%), Campylobacter jejuni (7%), enteropathogenic E. coli (7%), Shigella (4%) and enterotoxigenic Aeromonas sp. (1%). The highest incidence of infections was observed in the 3- to 25-month age group. Mixed infections were observed in 12% of the patients. Viral gastroenteritis was clinically mild and of short duration. Upper respiratory tract infections, vomiting and watery stools were common features. In contrast bacterial gastroenteritis was more severe; stools were frequently bloody and abdominal pain, cramps, shock, convulsions and milk intolerance were predominant clinical features. Comparative analysis revealed differential features of bacterial and viral gastroenteritis which should help clinicians to make a tentative diagnosis and to start treatment early.

Bacterial and viral causes of acute diarrhoea in children in Kuwait

Bacterial and viral causes of acute diarrhoea were studied prospectively for one year in 343 hospitalised young children in Kuwait. In 288 (84%) patients, one or more pathogens were identified compared with 12 of 86 (13.9%) children admitted with diseases other than diarrhoea (p less than 0.01). Forty-four (12.9%) of the patients were infected with two or more pathogens. Viral agents detected in the stools were rotaviruses (40.2%), enteric adenoviruses (1.7%), and enteroviruses (1.5%). Enterobacteria were isolated from the stools of 44% of the patients as follows: Salmonella (18.0%), enteropathogenic Escherichia coli (EPEC) (17.5%), enterotoxigenic E. coli (6.7%), Shigella (5.0%), Campylobacter jejuni (2.3%), Vibrio cholerae non-01 (2.3%), Yersinia enterocolitica (1.5%), and Aeromonas hydrophila (0.9%). The incidence of diarrhoea in children showed two seasonal peaks: during March-May and October-November. The present study indicates that Salmonella and EPEC are the major causes of bacterial gastroenteritis, while rotaviruses are the main cause of viral gastroenteritis in young children in Kuwait.

Detection of human rotavirus by using an alkaline phosphatase-conjugated synthetic DNA probe in comparison with enzyme-linked immunoassay and polyacrylamide gel analysis

An alkaline phosphatase-conjugated synthetic oligodeoxyribonucleotide probe was compared with polyacrylamide gel electrophoresis (PAGE) detection of rotavirus RNA as well as an enzyme-linked immunosorbent assay (ELISA) for the detection of rotavirus in stools from young children with gastroenteritis. The synthetic probe did not cross-react with bacterial causative agents of diarrheal disease. Extraction of viral RNA from stool samples with a phenol-chloroform mixture was suitable for most samples. In some cases fecal pigments interfered with the reaction of the probe with viral RNA. The use of ion-exchange chromatography to further purify viral RNA removed contaminating pigments and increased the sensitivity of the probe assay. Of 260 stool specimens, 77 (30%) were positive for rotavirus when tested by PAGE analysis of rotavirus RNA. The synthetic probe identified 71 rotavirus specimens when RNA obtained by phenol-chloroform extraction followed by chromatographic purification was used (sensitivity, 91.0%; specificity, 96.7%). The ELISA results also agreed well with the electrophoretic analysis (sensitivity, 98.7%; specificity 94%) and the probe assay (sensitivity, 90%; specificity, 100%). Discordant results between the ELISA and the probe assay were examined further by electron microscopy and PAGE analysis of viral RNA. The positive and negative predictive values of the probe assay in comparison with PAGE were 92.2 and 96.1%, respectively. Rotaviruses showing both long and short RNA electrophoretic patterns were detected by the probe. The probe assay coupled with chromatographic purification of rotavirus RNA is an effective method for detecting rotavirus and compares favorably with PAGE analysis and ELISA.

Outbreak of neonatal listeriosis in a regional hospital in Kuwait

Six newborns with Listeria monocytogenes infection were admitted to the same neonatal unit between 31 October and 3 December 1985. The index case, a preterm baby, was born to a mother who was febrile with an influenza-like illness at the time of delivery. This baby presented with Listeria sepsis and pneumonia. Another child was born from whose mother L. monocytogenes was isolated from the cervix with the same serotype as that in the CSF of her newborn. In the other cases blood and cervical cultures of the mothers were negative, while Listeria was isolated from the CSF of their babies. Five out of six infants developed meningitis between 9 and 12 days after birth. All isolates were serotype 4b and indistinguishable by phage typing. All babies were successfully treated without any major sequelae. Although cross-infection was strongly suggested, the source of the outbreak could not be established. This is the first documented report of human listeriosis in Kuwait.

Molecular epidemiology of human rotavirus infections based on genome segment variations in viral strains

Molecular epidemiology of rotavirus infections in 621 hospitalized children was investigated by analysis of migration patterns of viral genomic ribonucleic acid (RNA) segments by electrophoresis in polyacrylamide gels. Based on migration patterns of RNA segments of 184 rotavirus strains, seven different electropherotypes were identified: 146 (79.3%) strains were "long," and 38 (20.7%) were "short" electropherotypes; 61% belonged to a single dominant "long" electropherotype, which persisted throughout the 15-month period of study, whereas six other cocirculating types appeared at varying intervals. Electrophoretic migration patterns of RNA from viral isolates of two patients suggested mixed infections with different rotaviruses. There was a lack of correlation between the electrophoretic migration of segments 10 and 11 and serologically defined subgroup specificity in three of the rotavirus strains. Rotavirus infections and different electropherotypes were observed throughout the year.

Acute gastroenteritis: clinical features according to etiologic agents

The clinical manifestations in 595 children hospitalized with gastroenteritis during a 15-month time frame were studied. They were divided into eight groups according to etiologic agent: rotavirus (203 patients); Salmonellae (98); Escherichia coli (55); Campylobacter (36); Shigella (22); combined rotavirus and salmonellae (44); combined rotavirus and other bacteria (26); and no pathogen (111). The mean duration of diarrhea was shortest in the rotavirus and "no pathogen" groups (4.8 and 5.6 days, respectively) and longest with pure and mixed salmonella infections (12.3 and 12.9 days, respectively). Associated manifestations were most frequent with salmonellae and least frequent with rotavirus and E. coli infections. Malnutrition also was most common with salmonellae and lowest with rotavirus and E. coli. There were no differences in the frequency of hypernatremia. Hyponatremia was most frequently encountered with salmonella (25% compared to 9% in the rest of the patients). Evidence of septicemia was found in 22 patients, 21 of whom were in the salmonella groups. The four deaths in this series (0.7%) also were in the salmonellae groups. The clinical severity of salmonella infection in developing countries, particularly in young and malnourished children, warrants attention to more intensive management. The selective use of antibiotics may help reduce the mortality and morbidity of gastroenteritis.