Intraocular pressure as an index of ocular injury in orbital fractures

An improved method of screening for ocular injuries in patients sustaining orbital fractures is proposed. We performed a retrospective study of 107 patients who sustained orbital fractures. Intraocular pressures were measured on presentation in 17 patients and were found to be elevated on the side of the injury in eight patients, five (63%) of whom had significant ocular injury. No patient with normal intraocular pressure was found to have an ocular injury. In a prospective study, the intraocular pressures of 30 patients sustaining orbital fractures were measured. Twelve patients (40%) had normal (less than 22 mm Hg) and bilaterally symmetric (less than 3 mm Hg difference) intraocular pressures. One (8%) of these patients sustained ocular injury. In contrast, 18 patients (60%) had either an elevated intraocular pressure (greater than 22 mm Hg) or a difference between eyes of greater than or equal to 3 mm Hg. Eleven (61%) of these patients were found to have sustained an ocular injury. We conclude that intraocular hypertension or significant interocular pressure differences should alert the physician to a potential ocular injury.     

The lipoprotein-associated coagulation inhibitor that inhibits the factor VII-tissue factor complex also inhibits factor Xa: insight into its possible mechanism of action

Blood coagulation is initiated when plasma factor VII(a) binds to its essential cofactor tissue factor (TF) and proteolytically activates factors X and IX. Progressive inhibition of TF activity occurs upon its addition to plasma. This process is reversible and requires the presence of VII(a), catalytically active Xa, Ca2+, and another component that appears to be associated with the lipoproteins in plasma, a lipoprotein-associated coagulation inhibitor (LACI). A protein, LACI(HG2), possessing the same inhibitory properties as LACI, has recently been isolated from the conditioned media of cultured human liver cells (HepG2). Rabbit antisera raised against a synthetic peptide based on the N-terminal sequence of LACI(HG2) and purified IgG from a rabbit immunized with intact LACI(HG2) inhibit the LACI activity in human serum. In a reaction mixture containing VIIa, Xa, Ca2+, and purified LACI(HG2), the apparent half-life (t1/2) for TF activity was 20 seconds. The presence of heparin accelerated the initial rate of inhibition threefold. Antithrombin III alpha alone had no effect, but antithrombin III alpha with heparin abrogated the TF inhibition. LACI(HG2) also inhibited Xa with an apparent t1/2 of 50 seconds. Heparin enhanced the rate of Xa inhibition 2.5-fold, whereas phospholipids and Ca2+ slowed the reaction 2.5-fold. Xa inhibition was demonstrable with both chromogenic substrate (S-2222) and bioassays, but no complex between Xa and LACI(HG2) could be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Nondenaturing PAGE, however, showed that LACI(HG2) bound to Xa but not to X or Xa inactivated by diisopropyl fluorophosphate. Thus, LACI(HG2) appears to bind to Xa at or near its active site. Bovine factor Xa lacking its gamma-carboxyglutamic acid-containing domain, BXa(-GD), through treatment with alpha-chymotrypsin, was used to further investigate the Xa requirement for VIIa/TF inhibition by LACI(HG2). LACI(HG2) bound to BXa(-GD) and inhibited its catalytic activity against a small molecular substrate (Spectrozyme Xa), though at a rate approximately sevenfold slower than native BXa. Preincubation of LACI(HG2) with saturating concentrations of BXa(-GD) markedly retarded the subsequent inhibition of BXa. The VII(a)/TF complex was not inhibited by LACI(HG2) in the presence of BXa(-GD), and further, preincubation of LACI(HG2) with BXa(-GD) slowed the inhibition of VIIa/TF after the addition of native Xa. The results are consistent with the hypothesis that inhibition of VII(a)/TF involves the formation of a VIIa-TF-XA-LACI complex that requires the GD of XA.(ABSTRACT TRUNCATED AT 400 WORDS)     

Identification of C12orf4 as a gene for autosomal recessive intellectual disability

Intellectual disability (ID) is a major health problem in our society. Genetic causes of ID remain unknown because of its vast heterogeneity. Here we report two Finnish families and one Dutch family with affected individuals presenting with mild to moderate ID, neuropsychiatric symptoms and delayed speech development. By utilizing whole exome sequencing (WES), we identified a founder missense variant c.983T>C (p.Leu328Pro) in seven affected individuals from two Finnish consanguineous families and a deletion c.799_1034‐429delinsTTATGA (p.Gln267fs) in one affected individual from a consanguineous Dutch family in the C12orf4 gene on chromosome 12. Both the variants co‐segregated in the respective families as an autosomal recessive trait. Screening of the p.Leu328Pro variant showed enrichment in the North Eastern sub‐isolate of Finland among anonymous local blood donors with a carrier frequency of 1:53, similar to other disease mutations with a founder effect in that region. To date, only one Arab family with a three affected individuals with a frameshift insertion variant in C12orf4 has been reported. In summary, we expand and establish the clinical and mutational spectrum of C12orf4 variants. Our findings implicate C12orf4 as a causative gene for autosomal recessive ID.     

The role of previously unmeasured organic acids in the pathogenesis of severe malaria

IntroductionSevere falciparum malaria is commonly complicated by metabolic acidosis. Together with lactic acid (LA), other previously unmeasured acids have been implicated in the pathogenesis of falciparum malaria.MethodsIn this prospective study, we characterised organic acids in adults with severe falciparum malaria in India and Bangladesh. Liquid chromatography-mass spectrometry was used to measure organic acids in plasma and urine. Patients were followed until recovery or death.ResultsPatients with severe malaria (n=138), uncomplicated malaria (n=102), sepsis (n=32) and febrile encephalopathy (n=35) were included. Strong ion gap (mean±SD) was elevated in severe malaria (8.2 mEq/L±4.5) and severe sepsis (8.6 mEq/L±7.7) compared with uncomplicated malaria (6.0 mEq/L±5.1) and encephalopathy (6.6 mEq/L±4.7). Compared with uncomplicated malaria, severe malaria was characterised by elevated plasma LA, hydroxyphenyllactic acid (HPLA), α-hydroxybutyric acid and β-hydroxybutyric acid (all P<0.05). In urine, concentrations of methylmalonic, ethylmalonic and α-ketoglutaric acids were also elevated. Multivariate logistic regression showed that plasma HPLA was a strong independent predictor of death (odds ratio [OR] 3.5, 95 % confidence interval [CI] 1.6–7.5, P=0.001), comparable to LA (OR 3.5, 95 % CI 1.5–7.8, P=0.003) (combined area under the receiver operating characteristic curve 0.81).ConclusionsNewly identified acids, in addition to LA, are elevated in patients with severe malaria and are highly predictive of fatal outcome. Further characterisation of their sources and metabolic pathways is now needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1023-5) contains supplementary material, which is available to authorized users.     

Polymorphic and monomorphic HLA-DR determinants on human hematopoietic progenitor cells

The expression of monomorphic Ia-like antigens and polymorphic (allotypic) HLA-DR determinants on CFU-GM, BFU-E, CFU-E, and CFU-GEMM was studied in bone marrow and peripheral blood cells from normal healthy individuals. Using various polyclonal and monoclonal anti-Ia- like antibodies, the presence of HLA-DR backbone antigens was shown on all hematopoietic progenitor cells (HPC) studied, both in complement- dependent cytotoxicity assays and in fluorescence-activated cell sorting (FACS). The expression of allotypic determinants was demonstrated on all HPCs, using the HLA-DR typing sera anti-HLA-DR1, 2, 3, 4, 5, and 7. The Class II antigen MT-2 was also shown on all HPCs, using both monoclonal and alloantisera, whereas the MB-1 (DC-1) determinant could not be demonstrated on HPCs. This might open the possibility of removing MB-1-positive malignant cells from the graft in autologous bone marrow transplantation.     

Characterization of the IgG-Fc receptor on human platelets

To determine quantitatively the number and avidity of receptors for the Fc portion of IgG on human platelets, we have measured the binding to platelets of human monomeric monoclonal IgG, and of small covalently crosslinked polymers of IgG1 labeled with 125I. The binding of labeled IgG1 monomers to platelets is too weak to permit quantitation. The binding of dimers or larger polymers of IgG1 is much more avid (greater at 4 degrees C than 37 degrees C), is readily reversible, and is saturable. The number of receptor sites ranges from 400 to 2000 per platelet and the mean equilibrium association constant (Ka) for the binding of dimers at 4 degrees C is 2.2 x 10(7) M-1 +/- 0.9 x 10(7) M- 1. The binding is specific for the Fc portion of IgG, and IgG1 and IgG3 bind to the receptors much more avidly than IgG2 or IgG4. Unlabeled IgG1 dimers are about 7--8-fold more potent in inhibiting binding than are IgG1 monomers, and larger polymers are even more potent than dimers. Thus, the Fc receptors on platelets bind human IgG1 with the same specificity and similar avidity as Fc receptors on polymorphonuclear leukocytes (PMNs), but PMNs have about 300-fold more receptors per unit of surface area than platelets.     

Defects in oxidative phosphorylation. Biochemical investigations in skeletal muscle and expression of the lesion in other cells

Mitochondria are very vulnerable to genetic and environmental damage. If a patient is suspected of having a mitochondrial disease, elevated blood lactate, lowered blood free carnitine, abnormal urinary organic acids and carnitine esters and tissue histopathology may help with the diagnosis. For biochemical assessment of the defect, muscle is the tissue of choice even when involvement of other organs like heart or brain is more prominent.We have studied isolated muscle mitochondria and homogenates from muscle biopsies in 250 patients, and have detected in more than one third mitochondrial defects in oxidative phosphorylation, dehydrogenases, non-redox enzymes catalyzing synthesis of fuel molecules and in the carnitine system. Several patients showed more than one defect.We have selected eight patients to illustrate how a relatively simple series of investigations in both isolated mitochondria and homogenate can be used for the identification of defects in oxidative phosphorylation in a small amount of muscle (200 mg or more). Identification of the defect(s) is important since it may provide the basis for rational treatment. A minority of the patients recovered partly or completely, which is unique in treatment of inborn errors of subcellular organelles.An important aspect of mitochondrial dysfunction is the tissue specificity. The defect may be systemic but is often clinically expressed in only one or a few tissues. Rarely, tissue-specific defects can be understood on the basis of tissue-specificity of mitochondrial (iso-)enzymes. Mitochondrial deficiencies of all biotin enzymes and most CoA-linked enzymes are expressed in fibroblasts; most respiratory chain defects are not.When mitochondrial ATP synthesis has been compromised by a mitochondrial defect, secondary lesions may be generated by changes in mitochondrial protein synthesis, activated proteases and phospholipases, increased matrix CoA and resulting carnitine deficiency, decrease in Krebs cycle intermediates and increased free radical formation and lipid peroxidation.