Structure of some aliphatic dicarboxylic acids found in the urine of an infant with congenital lactic acidosis.

Gas chromatography/mass spectrometry was used to identify a series of acids in urine and serum from a child who died 26 h after birth in severe metabolic acidosis with high lactate excretion. cis-5-Decene-1, 10-dioic acid and cis-5-dodencene-1, 12-dioic acid were synthesized and used as references. The following acids were found: hexane-1,6-dioic acid, octane-1,8-dioic acid, decane-1,10-dioic acid, dodecane-1,12-dioic acid, cis-5-decene-1,10-dioic acid, cis-5-dodecen-1,12-dioic acid, cis-5-tetradecene-1,14-dioic acid, trans-3-decene-1,10-dioic acid, and trans-3-dodecene-1,12-dioic acid. The concentration of C6 to C14 acids in the patient's urine was 3.7 mol/mol of creatinine; it was less than 0.2 mol/mol of creatinine in eight normal newborns and approximately 0.1 mol/mol of creatinine in a case of fructose-1,6-biphosphatase deficiency with lactic acidosis. 5-cis-Dodecenedioic acid was present in highest concentration: 1 mol/mol of creatinine in urine and 61 mumol/liter in serum. We propose that impaired beta-oxidation, probably at the acyl-CoA-dehydrogenase step, resulted in the formation of the observed acids. The parents were consanguineous, and a sibling died with the same clinical picture, which suggests a genetic defect.     

Revised assays for the investigation of congenital lactic acidosis using 14C keto acids, eliminating problems associated with spontaneous decarboxylation

Improved methods using 14C keto acids for the investigation of patients with congenital lactic acidoses are described. The addition of rat serum to assay media reduces the spontaneous decarboxylation of [1-14C] and [2-14C] pyruvate and alpha-[1-14C]ketoglutarate to low levels. A study of the stability of pyruvate dehydrogenase in fibroblasts has shown that the activity is rapidly lost when cell membranes are broken unless homogenisation is done gently at -15 degrees C. Under these conditions broken cell preparations may be stored for up to 3 hours without loss of activity. Freezing and thawing results in unpredictable changes in pyruvate dehydrogenase activity. A quality control solution containing pyruvate dehydrogenase activity has been prepared which is stable for at least 6 months (coefficient of variation = 7.7%). Normal values for pyruvate dehydrogenase in fibroblasts range from 0.59 to 1.26 nmol . min-1 . mg-1 protein (mean = 0.98, n = 8) and pyruvate dehydrogenase deficient fibroblasts can be detected with confidence.     

Deficiency of the iron-sulfur clusters of mitochondrial reduced nicotinamide-adenine dinucleotide-ubiquinone oxidoreductase (complex I) in an infant with congenital lactic acidosis.

We report the case of an infant with hypoglycemia, progressive lactic acidosis, an increased serum lactate/pyruvate ratio, and elevated plasma alanine, who had a moderate to profound decrease in the ability of mitochondria from four organs to oxidize pyruvate, malate plus glutamate, citrate, and other NAD+-linked respiratory substrates. The capacity to oxidize the flavin adenine dinucleotide-linked substrate, succinate, was normal. The most pronounced deficiency was in skeletal muscle, the least in kidney mitochondria. Enzymatic assays on isolated mitochondria ruled out defects in complexes II, III, and IV of the respiratory chain. Further studies showed that the defect was localized in the inner membrane mitochondrial NADH-ubiquinone oxidoreductase (complex I). When ferricyanide was used as an artificial electron acceptor, complex I activity was normal, indicating that electrons from NADH could reduce the flavin mononucleotide cofactor. However, electron paramagnetic resonance spectroscopy performed on liver submitochondrial particles showed an almost total loss of the iron-sulfur clusters characteristic of complex I, whereas normal signals were noted for other mitochondrial iron-sulfur clusters. This infant is presented as the first reported case of congenital lactic acidosis caused by a deficiency of the iron-sulfur clusters of complex I of the mitochondrial electron transport chain.     

MCL1 and MCL6 Compared to V1 and V6 in Distinguishing Aberrant Supraventricular from Ventricular Ectopic Beats

Use of V1 and V6 has been suggested for distinguishing aberrant supraventricular from ventricular ectopy. For two decades, "modified" leads MCL1 and MCL6 have been widely used as V1 and V6 substitutes for bedside monitoring, but their use has never been validated. To determine the value of MCL1 and MCL6, 81 morphologically distinct wide QRS ectopic beats were recorded from 46 patients during cardiac electrophysiological study. As determined by the His-bundle electrogram, 31 of the ectopics were aberrant supraventricular, 50 were ventricular. A new criterion, measurement of QRS onset to the predominant peak or nadir of the complex, was valuable in diagnosing wide complexes in MCL6 and V6. An interval of 50 msec or less predicted aberrant supraventricular ectopy; an interval of 70 msec or more predicted ventricular ectopy. There was agreement between the modified and conventional precordial leads regarding which QRS patterns were useful in distinguishing aberrant supraventricular from ventricular ectopy. A greater proportion of wide complexes in MCL1 and V1 exhibited patterns useful in making the diagnosis compared to MCL6 and V6. Using well-established criteria, the proportion of correct diagnoses that was made from individual leads was: MCL1 = 86%, V1 = 85%, MCL6 = 72%, V6 = 67%. The bedside leads (MCL1 and MCL6) were not statistically different in diagnostic accuracy from their conventional lead counterparts (V1 and V6); however, MCL1 and V1 were superior to MCL6 and V6. When the new criterion was added to make the diagnosis from MCL6 and V6, no difference in diagnostic accuracy was present between the four leads.     

Gas chromatographic and mass spectrometric studies on urinary organic acids in a patient with congenital lactic acidosis due to pyruvate decarboxylase deficiency.

Detailed studies, using gas chromatography and mass spectrometric methods, of the urinary organic acids excreted by a patient with proven pyruvate decarboxylase deficiency are reported. In addition to the greatly-increased levels of lactate and pyruvate, marked elevation in the levels of 2-oxoglutaric, malic, and isocitric acids were observed, with associated increases 2-hydroxyglutaric, fumaric, succinic, and glyceric acids, and reduced citric acid excretion. The levels of excretion during clinically static and acute periods are compared to those in a normal neonate and normal infants. The metabolites observed indicate a probable defect in the oxidation of pyruvate by pyruvate dehydrogenase and suggest the presence of secondary defects in the tricarboxylic acid cycle. Studies of this type may enable the relatively rapid identification of the probable underlying enzyme deficiency in cases of congenital lactic acidosis, prior to confirmatory enzyme studies.     

First report of a Wautersiella falsenii isolated from the urine of an infant with pyelonephritis

Here, we report the first isolation of Wautersiella falsenii from the urine of an infant with a complicated urinary tract infection. W. falsenii was correctly identified by matrix-assisted laser desorption ionisation time of flight mass spectrometry. The identification was confirmed by 16S polymerase chain reaction. Susceptibility test results of this isolate are reported. Ciprofloxacin treatment resulted in clinical and microbiological improvement.     

3‐Hydroxyisobutyryl‐CoA hydrolase deficiency in an infant with developmental delay and high anion gap acidosis

Due to the rarity of this disorder, paying attention to diagnostic clues is important. Low valine formula seems to be effective in improvement of patient''s symptoms. Prevention of consanguineous marriage is the best way to prevent this disease.     

Ventilatory Response to Hypercapnia in C5–8 Chronic Tetraplegia: The Effect of Posture

Ben-Dov I, Zlobinski R, Segel MJ, Gaides M, Shulimzon T, Zeilig G. Ventilatory response to hypercapnia in C_5–8 chronic tetraplegia: the effect of posture.

Objective

To study the effect of posture on the hypercapnic ventilatory responses (HCVR).

Design

Nonrandomized controlled study.

Setting

Rehabilitation hospital and a pulmonary institute.

Participants

Patients with neurologically stable C_5–8 tetraplegia (n=12) and healthy control subjects (n=7).

Interventions

Not applicable.

Main Outcome Measures

Supine and seated forced vital capacity (FVC) and HCVR, and supine and erect blood pressure.

Results

FVC in the sitting position was reduced in patients with tetraplegia (52±13% predicted); supine FVC was 21% higher (P=.0005). In the sitting position, HCVR was lower in patients than in controls (0.8±0.4 vs 2.46±0.3L/min/mmHg, P<.001). Supine HCVR was not significantly different between the groups. When HCVR was normalized to FVC, there was still a significant difference between patients and controls in the sitting position. Patients with tetraplegia were orthostatic (mean supine blood pressure 91±13mmHg vs mean erect blood pressure 61±13mmHg, respectively, P<.0001). The magnitude of the orthostatism correlated with that of the postural change in HCVR (r=.93, P<.0001).

Conclusions

Respiratory muscle weakness may contribute to the attenuated HCVR in tetraplegia. However, the observation that supine HCVR is still low even when normalized to FVC suggests a central posture-dependent effect on the HCVR, which may be linked to the postural effect on arterial blood pressure.     

In vitro fibroblast studies in a patient with C6-C10-dicarboxylic aciduria: evidence for a defect in general acyl-CoA dehydrogenase

Fatty acid oxidation studies were performed on cultured fibroblasts from a patients who had suffered from a Reye's syndrome-like episode, and who excreted adipic acid, suberic acid, sebacic acid, 5-OH-hexanoic acid, and hexanoylglycine. Assays using fatty acids of different chain length on both intact and disrupted cells indicated that the patient had a defect of the general (medium-chain) acyl-CoA dehydrogenase apoenzyme.     

Biosynthesis of prostacyclin and thromboxane A2 during chronic hypoxaemia in children with cyanotic congenital heart disease

The high risk of vaso-occlusive events in children younger than 4 years with cyanotic congenital heart disease and polycythaemia has been attributed to increased thromboxane (Tx) A₂ formation. In older children with cyanotic congenital heart disease, however, the risk of vaso-occlusive events is much lower. We therefore hypothesized that the formation of TxA₂ and prostacyclin is not disturbed in this age group. We measured urinary excretion of stable index metabolites of in vivo TxA₂ and prostacyclin formation by gas chromatography–mass spectrometry in nine children (age 5.9–14.4, median 8.7 years) with cyanotic congenital heart disease, and in nine healthy, age-matched control subjects. The patients excreted less 2,3-dinor-TxB₂ (systemic TxA₂ formation, P =0.03), 2,3-dinor-6-keto-PGF_1α (systemic prostacyclin formation, P =0.03) and TxB₂ (renal TxA₂ formation, P =0.01) than the control subjects. We conclude that in children older than 5 years with cyanotic congenital heart disease, endogenous synthesis of TxA₂ and prostacyclin is not stimulated. This result may explain the lower risk of vaso-occlusive events in this age group as compared with younger children. In addition, our results suggest that chronic hypoxaemia may affect the in vivo formation of TxA₂ and prostacyclin and the metabolic disposition of TxB₂.     

FiO2 Delivered By a Turbine Portable Ventilator with an Oxygen Concentrator in an Austere Environment

Background

Management of critically ill patients in austere environments is a logistic challenge. Availability of oxygen cylinders for the mechanically ventilated patient may be difficult in such a context. A solution is to use a ventilator able to function with an oxygen concentrator.

Objectives

We tested the SeQual Integra™ (SeQual, San Diego, CA) 10-OM oxygen concentrator paired with the Pulmonetic System^® LTV 1000 ventilator (Pulmonetic Systems, Minneapolis, MN) and evaluated the delivered fraction of inspired oxygen (FiO₂) across a range of minute volumes and combinations of ventilator settings.

Methods

Two LTV 1000 ventilators were tested. The ventilators were attached to a test lung and FiO₂ was measured by a gas analyzer. Continuous-flow oxygen was generated by the OC from 0.5 L/min to 10 L/min and injected into the oxygen inlet port of the LTV 1000. Several combinations of ventilator settings were evaluated to determine the factors affecting the delivered FiO₂.

Results

The LTV 1000 ventilator is a turbine ventilator that is able to deliver high FiO₂ when functioning with an oxygen concentrator. However, modifications of the ventilator settings such as increase in minute ventilation affect delivered FiO₂ even if oxygen flow is constant on the oxygen concentrator.

Conclusions

The ability of an oxygen concentrator to deliver high FiO₂ when used with a turbine ventilator makes this method of oxygen delivery a viable alternative to cylinders in austere environments when used with a turbine ventilator. However, FiO₂ has to be monitored continuously because delivered FiO₂ decreases when minute ventilation is increased.     

临床与环境标本分离的大肠埃希菌blaCTX-M-14基因环境和菌株同源性分析

目的分析临床与环境标本分离的大肠埃希菌blaCTX-M-14基因环境和菌株同源性。方法收集2014年6月至2014年8月我院临床与环境标本分离的大肠埃希菌共255株,PhoenixTM-100鉴定细菌种类并测定最小抑菌浓度,纸片扩散法测定超广谱β-内酰胺酶表型,PCR扩增blaCTX-M-14基因;接合实验、质粒复制子分型分析质粒特征;脉冲场凝胶电泳和多位点序列分型对菌株分型。结果 blaCTX-M-14基因的阳性共26株。多数菌株(42.3%,11/26)含有F型质粒,且多具有可转移性。多位点序列分型多为ST131(30.8%,8/26)。仅有4株菌能在环境或大便标本中找到同源株。多数菌株(61.5%,16/26)blaCTX-M-14基因环境均具有相同的模式:上游有ISEcp1,同时下游有IS903。结论 blaCTX-M-14基因可通过医院环境或体内移位获得,但其广泛传播的原因可能与其编码在F型质粒上及其基因环境中存在ISEcp1和IS903有关。     

Blood group A antigen expression in platelets is prominently associated with glycoprotein Ib and IIb. Evidence for an A1/A2 difference

Blood group ABH antigens are associated with platelets as intrinsic determinants and extrinsically adsorbed antigens, and exist both on glycosphingolipids and on glycoproteins (GPs). We now provide direct evidence that the blood group ABH antigens are prominently associated with platelet GPIb and GPIIb. By immunoprecipitation, a murine monoclonal anti-A antibody precipitated surface-biotin-labelled blood group A₁ platelet membrane proteins with electrophoretic characteristics identical to those of GPIb/IX and GPIIb/IIIa. By immunoblotting of SDS-PAGE separated blood group A₁ platelet proteins the monoclonal anti-A antibody bound to proteins with electrophoretic characteristics identical to those of GPIb and GPIIb. When immunoaffinity purified GPIb/IX and GPIIb/IIIa, derived from blood group O, A₁ and A₂ platelets, were employed for immunoblotting, GPIb and GPIIb only from A₁ platelets bound the monoclonal anti-A antibody. By ELISA, wherein monoclonal antibodies specific for GPIb (AP1) and the GPIIb/IIIa complex (AP2) were used to capture and hold antigens from platelet lysate, human anti-A antibodies reacted with these proteins derived from blood group A₁ platelets; proteins from blood group A₂, O and B platelets showed no reactivity. These results indicate that blood group A antigen is associated with GPIb and GPIIb derived from blood group A₁ but not A₂ platelets.     

Critical role of ADP interaction with P2Y12 receptor in the maintenance of αIIbβ3 activation: association with Rap1B activation

OBJECTIVE: Platelet integrin alpha(IIb)beta3 plays a crucial role in platelet aggregation, and the affinity of alpha(IIb)beta3 for fibrinogen is dynamically regulated. Employing modified ligand-binding assays, we analyzed the mechanism by which alpha(IIb)beta3 maintains its high-affinity state. METHODS AND RESULTS: Washed platelets adjusted to 50 x 10(3) microL(-1) were stimulated with 0.2 U mL(-1) thrombin or 5 microm U46619 under static conditions. After the completion of alpha(IIb)beta3 activation and granule secretion, different kinds of antagonists were added to the activated platelets. The activated alpha(IIb)beta3 was then detected by fluorescein isothiocyanate (FITC)-labeled PAC1. The addition of 1 mum AR-C69931MX (a P2Y12 antagonist) or 1 mm A3P5P (a P2Y1 antagonist) disrupted the sustained alpha(IIb)beta3 activation by approximately 92% and approximately 38%, respectively, without inhibiting CD62P or CD63 expression. Dilution of the platelet preparation to 500 microL(-1) also disrupted the sustained alpha(IIb)beta3 activation, and the disruption by such dilution was abrogated by the addition of exogenous adenosine 5'-diphosphate (ADP) in a dose-dependent fashion. The amounts of ADP released from activated platelets determined by high-performance liquid chromatography were compatible with the amounts of exogenous ADP required for the restoration. We next examined the effects of antagonists on protein kinase C (PKC) and Rap1B activation induced by 0.2 U mL(-1) thrombin. Thrombin induced long-lasting PKC and Rap1B activation. AR-C69931MX markedly inhibited Rap1B activation without inhibiting PKC activation. CONCLUSIONS: Our data indicate that the continuous interaction between released ADP and P2Y12 is critical for the maintenance of alpha(IIb)beta3 activation.     

High prevalence of ESBL-producing Escherichia coli isolates among hemodialysis patients in Portugal: appearance of ST410 with the blaCTX-M-14 gene

Ten extended-spectrum β-lactamase–producing Escherichia coli isolates were detected among 121 fecal samples (8.3%) recovered from hemodialysis patients in Portugal. The isolates harbored the bla_CTX-M-15, bla_CTX-M-14a, and/or bla_CTX-M-1 genes. A new sequence type, ST2229, was detected, and this study also reports, for the first time, ST410 CTX-M-14–producing isolates.