Motor functions in rat hindlimb muscles following neonatal sciatic nerve crush.

The sciatic nerve was crushed in the right hindlimb in newborn (3-8 h old) rats. Two to four months later, electromyographic activity was recorded from both the control and reinnervated ankle extensor muscles soleus or lateral gastrocnemius and from the ankle flexor muscle tibialis anterior. Tonic postural activity was present in the extensor muscles on both sides during quiet stance. The control flexor muscles were usually silent in this situation, but the reinnervated flexors exhibited abnormal sustained activity. During locomotion, the control extensors were activated during the stance phase and their mean burst made up 61.5% of the step cycle. The control tibialis anterior muscle fired only during the swing phase, with the burst lasting 18.1% of the step cycle. In the reinnervated extensor muscles, the mean burst duration was decreased (46% of the cycle) but the basic locomotor pattern was not impaired. The reinnervated tibialis muscle, however, was activated abnormally, with one appropriate flexor burst during the swing phase and an "extensor-like" burst during the stance phase of the step. Reflex responses to stretch were weak or absent on the operated side. Histological examination showed that the reinnervated soleus and tibialis muscles were almost devoid of muscle spindles. The motor unit mean firing rates in the reinnervated soleus (22 imp/s) and lateral gastrocnemius (45 imp/s) matched those of the control muscles (25 and 42 imp/s, respectively). In contrast to the phasic, high-frequency firing (52-80 imp/s) in the control tibialis, the reinnervated tibialis motor units fired at significantly lower rates (22-56 imp/s).(ABSTRACT TRUNCATED AT 250 WORDS)     

A truncating PET100 variant causing fatal infantile lactic acidosis and isolated cytochrome c oxidase deficiency

Isolated mitochondrial complex IV (cytochrome c oxidase) deficiency is an important cause of mitochondrial disease in children and adults. It is genetically heterogeneous, given that both mtDNA-encoded and nuclear-encoded gene products contribute to structural components and assembly factors. Pathogenic variants within these proteins are associated with clinical variability ranging from isolated organ involvement to multisystem disease presentations. Defects in more than 10 complex IV assembly factors have been described including a recent Lebanese founder mutation in PET100 in patients presenting with Leigh syndrome. We report the clinical and molecular investigation of a patient with a fatal, neonatal-onset isolated complex IV deficiency associated with multiorgan involvement born to consanguineous, first-cousin British Asian parents. Exome sequencing revealed a homozygous truncating variant (c.142C>T, p.(Gln48*)) in the PET100 gene that results in a complete loss of enzyme activity and assembly of the holocomplex. Our report confirms PET100 mutation as an important cause of isolated complex IV deficiency outside of the Lebanese population, extending the phenotypic spectrum associated with abnormalities within this gene.     

Iron-regulated hemolysin production and utilization of heme and hemoglobin by Vibrio cholerae.

El Tor and non-O1 strains of Vibrio cholerae were analyzed to determine whether synthesis of secreted hemolysin was influenced by the concentration of iron in the medium. Synthesis of hemolysin was found to be iron regulated in both El Tor and non-O1 isolates. Increased levels of hemolytic activity were detected in supernatants of iron-starved cells. Spontaneous hemolysin-deficient mutants of one non-O1 strain were found to occur at high frequency. These variants also failed to synthesize vibriobactin, the iron transport compound utilized by V. cholerae. Another non-O1 strain was found to synthesize both hemolysin and vibriobactin constitutively. When the cloned Escherichia coli fur gene, encoded on the plasmid pABN203, was introduced into this constitutive strain, normal iron regulation of both hemolysin and vibriobactin was reestablished. The ability of V. cholerae to utilize mammalian iron compounds was determined, and it was found that both hemin and hemoglobin could serve as sole sources of iron.     

Isolation of Stomatococcus mucilaginosus from drug user with endocarditis.

Stomatococcus mucilaginosus was isolated from the blood of a patient with endocarditis and a past history of drug abuse and aortic valve replacement. At autopsy, Gram stain of the aortic valve revealed gram-positive cocci. Our isolate was atypical for S. mucilaginosus in that colonies were nonmucoid and nonadherent to agar surfaces. Cellular capsules were demonstrated by light and electron microscopy. Phenotypic characteristics identified by conventional methods as well as profile numbers obtained by using two commercial identification systems for staphylococci, the API Staph-Ident and the dms Staph Trac, are presented. Practical tests that differentiate S. mucilaginosus from the genera Micrococcus and Staphylococcus include growth on nutrient agar containing salt and lysostaphin susceptibility. Additional tests that helped differentiate our isolate from group D streptococci included hydrolysis of L-pyrrolidonyl-beta-naphthylamide and streptococcal serogrouping.     

Complement activation by hydroxyethylmethacrylate-ethylmethacrylate copolymers

Certain biomaterials, including nylon oxygenator and cellulosic dialysis membranes, are potent activators of human complement. In this study, the effect of polymers containing 2-hydroxyethyl methacrylate (HEMA) on the human complement system was investigated. Copolymers of HEMA with ethylmethacrylate (EMA) varying from 100 to 40% HEMA in the monomer made by radiation initiation were used to coat glass discs. These were equilibrated with human plasma in vitro and the degree of complement activation was quantitated by C3a radio immunoassay. Significant activation was caused by copolymers made from monomers containing 60% or greater HEMA. A direct relationship between the amount of activation and the percentage of HEMA was found. The degree of activation by poly HEMA, when corrected for surface area, was quite similar to that observed for dialysis and oxygenator membranes. Similar observations were made when solid casts of crosslinked HEMA/N-vinylpyrrolidone (NVP) copolymer gels were tested, but the magnitude of activation was much greater. The results are significant because complement activation may play an important role in the response to foreign surfaces, in both extravascular and intravascular settings. A new concept of molecular biocompatibility is proposed in which surfaces eliciting molecular transformations in any of the biological defense systems are deemed nonbiocompatible. By this criterion, the hydrogel poly-HEMA, which has so frequently been thought of as biocompatible, is considered to be a molecularly non-biocompatible material.     

Effect of differences in antibody and complement requirements on phagocytic uptake and intracellular killing of "c" protein-positive and -negative strains of type II group B streptococci

The influence of antibody and complement on the polymorphonuclear leukocytic uptake and killing of type II group B streptococci (GBS) was examined with 11 adult sera and three type II strains possessing the trypsin-resistant and trypsin-sensitive components (II/TR+TS) of the "c" (formerly Ibc) protein or two type II strains lacking both components (II/no c) of the c protein. All tested sera mediated a greater than 1 log10 reduction in colony-forming units (CFUR) of a type II/no c strain, even in the absence of measurable type-specific antibody (less than 1.08 micrograms/ml), but only 5 of 11 mediated a greater than 1 log10 CFUR of any type II/TR/TS strain, even in the presence of moderate levels of type-specific antibody. The classical pathway of complement activation appeared to be more important than the alternative pathway, and even absorbed or immunoglobulin G (IgG)-depleted serum (IgG, 10 mg/dl) mediated a greater than 1 log10 CFUR without magnesium ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (magnesium EGTA) chelation. Chelation with magnesium EGTA reduced the CFUR in 4 of 11 test sera and greatly reduced the CFUR in absorbed or IgG-depleted sera for type II/no c strains. Despite variation in the phagocytic killing of two representative strains of type II GBS, both strains were well phagocytized, as measured by radiolabeled bacterial uptake or electron microscopy. This study suggested that poorly killed type II/TR+TS GBS were easily phagocytized but apparently resisted intracellular killing.     

The feasibility of task-sharing the identification,emergency treatment,and referral for women with pre-eclampsia by community health workers in India

Background

Hypertensive disorders are the second highest direct obstetric cause of maternal death after haemorrhage, accounting for 14% of maternal deaths globally. Pregnancy hypertension contributes to maternal deaths, particularly in low- and middle-income countries, due to a scarcity of doctors providing evidence-based emergency obstetric care. Task-sharing some obstetric responsibilities may help to reduce the mortality rates. This study was conducted to assess acceptability by the community and other healthcare providers, for task-sharing by community health workers (CHW) in the identification and initial care in hypertensive disorders in pregnancy.

Methods

This study was conducted in two districts of Karnataka state in south India. A total of 14 focus group discussions were convened with various community representatives: women of reproductive age (N = 6), male decision-makers (N = 2), female decision-makers (N = 3), and community leaders (N = 3). One-to-one interviews were held with medical officers (N = 2), private healthcare OBGYN specialists (N = 2), senior health administrators (N = 2), Taluka (county) health officers (N = 2), and obstetricians (N = 4). All data collection was facilitated by local researchers familiar with the setting and language. Data were subsequently transcribed, translated and analysed thematically using NVivo 10 software.

Results

There was strong community support for home visits by CHW to measure the blood pressure of pregnant women; however, respondents were concerned about their knowledge, training and effectiveness. The treatment with oral antihypertensive agents and magnesium sulphate in emergencies was accepted by community representatives but medical practitioners and health administrators had reservations, and insisted on emergency transport to a higher facility. The most important barriers for task-sharing were concerns regarding insufficient training, limited availability of medications, the questionable validity of blood pressure devices, and the ability of CHW to correctly diagnose and intervene in cases of hypertensive disorders of pregnancy.

Conclusion

Task-sharing to community-based health workers has potential to facilitate early diagnosis of the hypertensive disorders of pregnancy and assist in the provision of emergency care. We identified some facilitators and barriers for successful task-sharing of emergency obstetric care aimed at reducing mortality and morbidity due to hypertensive disorders of pregnancy.