Nonketotic hyperglycinemia. Glycine accumulation due to absence of glycerine cleavage in brain

Glycine concentrations were measured in plasma and cerebrospinal fluid of five patients in different types of hyperglycinemia to determine why severe neurologic deterioration is confined to the so-called nonketotic form of hyperglycinemia. Glycine content and glycine-cleavage enzyme activity were also determined in brain obtained in autopsy from three of these patients. Spinal-fluid glycine concentrations were 15 to 30 times above normal in patients with nonketotic hyperglycinemia, but were normal in those with hyperglycinemias of undetermined type who had comparable elevations of plasma glycine. Glycine content was two to four times above normal in several brain regions, and brain glycine cleavage enzyme activity was absent in two patients dying of nonketotic hyperglycinemia. By contrast, glycine content was normal and glycine cleavage activity present in the brain of an infant who died of hyperglycinemia of unknown cause. These results suggest that elevated glycine levels may be harmless in blood, but lethal in brain.

Ocular neuromyotonia. A clinical description of six patients

We report the cases of six patients with ocular neuromyotonia, a disorder believed to result from episodic involuntary discharge of ocular motor nerves producing sustained and inappropriate contraction of their respective ocular muscles. Transient disturbances of ocular motility and diplopia result. Four patients had involvement of ocular muscles supplied by the third cranial nerve: one had presumed involvement of the superior oblique muscle, and one the lateral rectus muscle, suggesting abnormal discharge in the fourth and sixth cranial nerves, respectively. Four of six patients received prior radiation therapy for pituitary tumors, implying a possible pathogenic link. Three patients improved after treatment with membrane-stabilizing medication, suggesting that unstable membranes of injured ocular motor axons may generate spontaneous impulses, which produce involuntary sustained and inappropriate ocular muscle contraction.

High phenotypic correlations among siblings with autism and pervasive developmental disorders

The objective of this study was to examine familial factors influencing clinical variation in sibships that contained at least 2 children affected with autism or another form of pervasive developmental disorder (PDD). The sample included a total of 60 families, 23 with multiple cases of PDD and 37 with a single affected child. Measurements of IQ, adaptive behaviors in socialization and communication, and autistic symptoms were taken on all affected children. A high intraclass correlation, especially on IQ and an index of social behaviors, was observed between affected children from the same family. In contrast, low correlations were observed on measurements of IQ and adaptive behavior between affected and unaffected children from the same family. These data indicate that variation in severity of PDD is influenced by familial, and probably genetic, mechanisms. The results are discussed in relation to current theories on the genetics of autism and the heritable mechanisms underlying variations in clinical severity.

Botulinum toxin treatment of spasticity in diplegic cerebral palsy: a randomized, double-blind, placebo-controlled, dose-ranging study

This study evaluated the efficacy and safety of three doses of botulinum toxin A (BTX-A; Dysport) in 125 patients (mean age 5.2 years, SD 2; 54% male)with dynamic equinus spasticity during walking. Participants were randomized to receive Dysport (10, 20, or 30 units/kg) or placebo to the gastrocnemius muscle of both legs. Muscle length was calculated from electrogoniometric measurements and the change in the dynamic component of gastrocnemius shortening at four weeks was prospectively identified as the primary outcome measure. All treatment groups showed statistically significant decreases in dynamic component compared with placebo at 4 weeks. Mean improvement in dynamic component was most pronounced in the 20 units/kg group, being equivalent to an increase in dorsiflexion with the knee extended at 19 degrees, and was still present at 16 weeks. The safety profile of the toxin appears satisfactory.

Aspartate-taurine imbalance in dominantly inherited olivopontocerebellar atrophy

Amino acids were measured in autopsied brain from two patients who died with a dominantly inherited form of olivopontocerebellar atrophy. Neuropathologic changes found in the brain of these patients suggested a loss of cerebellar climbing fibers. The contents of aspartic acid, gamma-aminobutyric acid, and homocarnosine were reduced in the cerebellar cortex and the dentate nucleus, while taurine content was markedly elevated in the same brain regions. These findings are compatible with the possibility that aspartic acid is the excitatory synaptic transmitter of the climbing fibers and taurine is the inhibitory neurotransmitter of one or more types of interneurons in the cerebellum.

The published DNA sequence of human cytomegalovirus strain AD169 lacks 929 base pairs affecting genes UL42 and UL43

Compared with the published DNA sequence (M. S. Chee, et al. Curr. Top. Microbiol. Immunol. 154:125-170, 1990), most isolates of human cytomegalovirus strain AD169 contain an additional 929 bp after nucleotide 54612. This results in a changed reading frame for the 5'-terminal 50 codons of gene UL42 and expansion of gene UL43 (a US22 family member) from 187 (3'-truncated) to 423 (full-length) codons. The UL42 and UL43 gene products are nonessential for growth in culture.

High functioning autism and Childhood Disintegrative Disorder in half brothers

Childhood Disintegrative Disorder (CDD) is grouped with autism as a subtype of Pervasive Developmental Disorder (PDD) in ICD-10 and DSM-IV. This is the first report of autism and CDD cosegregating within a sibship. J. P. and M. P. are half-brothers with the same mother. J. P. is an 18-year-old with impairments in communication, social reciprocity, and stereotypies and was diagnosed with autism. M. P. is a 7-year-old who developed normally to 2 years 4 months. He then underwent a profound regression, becoming nonverbal and socially withdrawn, and lost adaptive skills. Investigations did not reveal any neurodegenerative process. M. P. was diagnosed with CDD. The rarity of the two conditions suggests a shared transmissible mechanism. The implications for autism/PDD genetic studies are discussed.

Cerebrospinal fluid and plasma glutamine elevation by anticonvulsant drugs: a potential diagnostic and therapeutic trap

Administration of phenobarbitone or primidone can produce an elevation of glutamine and ornithine concentrations, together with a reduction of urea concentrations, in the fasting plasma and CSF of some infants, and in the CSF of some older epileptic patients. These two anticonvulsant drugs may interfere with the metabolic conversion of ammonia to urea, possibly by enzyme inhibition at the step of carbomoyl phosphate synthesis. The elevation of glutamine in plasma and CSF can mimic values found in some hyperammonemias. Recognition of this drug reaction can prevent erroneous diagnoses of genetically-determined urea cycle disorders and subsequent inappropriate therapy.

Cyclic transitions between higher order motifs underlie sustained asynchronous spiking in sparse recurrent networks

A basic—yet nontrivial—function which neocortical circuitry must satisfy is the ability to maintain stable spiking activity over time. Stable neocortical activity is asynchronous, critical, and low rate, and these features of spiking dynamics contribute to efficient computation and optimal information propagation. However, it remains unclear how neocortex maintains this asynchronous spiking regime. Here we algorithmically construct spiking neural network models, each composed of 5000 neurons. Network construction synthesized topological statistics from neocortex with a set of objective functions identifying naturalistic low-rate, asynchronous, and critical activity. We find that simulations run on the same topology exhibit sustained asynchronous activity under certain sets of initial membrane voltages but truncated activity under others. Synchrony, rate, and criticality do not provide a full explanation of this dichotomy. Consequently, in order to achieve mechanistic understanding of sustained asynchronous activity, we summarized activity as functional graphs where edges between units are defined by pairwise spike dependencies. We then analyzed the intersection between functional edges and synaptic connectivity- i.e. recruitment networks. Higher-order patterns, such as triplet or triangle motifs, have been tied to cooperativity and integration. We find, over time in each sustained simulation, low-variance periodic transitions between isomorphic triangle motifs in the recruitment networks. We quantify the phenomenon as a Markov process and discover that if the network fails to engage this stereotyped regime of motif dominance “cycling”, spiking activity truncates early. Cycling of motif dominance generalized across manipulations of synaptic weights and topologies, demonstrating the robustness of this regime for maintenance of network activity. Our results point to the crucial role of excitatory higher-order patterns in sustaining asynchronous activity in sparse recurrent networks. They also provide a possible explanation why such connectivity and activity patterns have been prominently reported in neocortex.

Neocortical spiking activity tends to be low-rate and non-rhythmic, and to operate near the critical point of a phase transition. It remains unclear how this kind of spiking activity can be maintained within a neuronal network. Neurons are leaky and individual synaptic connections are sparse and weak, making the maintenance of an asynchronous regime a nontrivial problem. Higher order patterns involving more than two units abound in neocortex, and several lines of evidence suggest that they may be instrumental for brain function. For example, stable activity in vivo displays elevated clustering dominated by specific three-node (triplet) motifs. In this study we demonstrate a link between the maintenance of asynchronous activity and triplet motifs. We algorithmically build spiking neural network models to mimic the topology of neocortex and the spiking statistics that characterize wakefulness. We show that higher order coordination of synapses is always present during sustained asynchronous activity. Coordination takes the form of transitions in time between specific triangle motifs. These motifs summarize the way spikes traverse the underlying synaptic topology. The results of our model are consistent with numerous experimental observations, and their generalizability to other weakly and sparsely connected networks is predicted.

Assessing the impact of nonspecific binding on oligonucleotide bioanalysis

Aim: Accurate and reliable quantification of oligonucleotides can be difficult, which has led to an increased focus on bioanalytical methods for more robust analyses. Recent advances toward mitigating sample losses on liquid chromatography (LC) systems have produced recovery advantages for oligonucleotide separations. Results & methodology: LC instruments and columns constructed from MP35N metal alloy and stainless steel columns were compared against LC hardware modified with hybrid inorganic-organic silica surfaces. Designed to minimize metal-analyte adsorption, these surfaces demonstrated a 73% increase in 25-mer phosphorothioate oligonucleotide recovery using ion-pairing reversed-phase LC versus standard LC surfaces, most particularly upon initial use. Conclusion: Hybrid silica chromatographic surfaces improve the performance, detection limits and reproducibility of oligonucleotide bioanalytical assays.

A thyrotropin radioimmunoassay kit evaluated vs two reference assays

We evaluated a double-antibody radioimmunoassay kit for thyrotropin that includes calibrators prepared in a matrix of human serum and involves overnight nonequilibrium. Results were compared with those from two reference assays for thyrotropin. The range of within-assay CVs for the kit for thyrotropin values between 0.9 and 2.4 milli-int. units/L was 2.2 to 5.3%, that for between-assay CVs was 8.3 to 30%. The estimated minimum detectable concentration of thyrotropin was 0.6 milli-int. unit/L. We saw no cross reactivity with human choriogonadotropin by any of 48 sera from pregnant women. The original lot of serum specified as thyrotropin-free contained small but measurable amounts of thyrotropin; a second lot did not. Clinical data generated with the kit and the reference assays correlated well and were consistent with the clinical status of various categories of patients.

Naked oats in grower and finisher diets for male chicken roasters and female turkey broilers

Two experiments were conducted to evaluate naked oats as a feedstuff for male chicken roaster and female turkey broilers. In exp. 1, grower and finisher roaster diets were formulated to contain 18, 36, 54, or 72% naked oats (Avena nuda L. 'Tibor'). The starter diet contained no naked oats. Two trials were conducted utilizing 1344 birds. Treatment diets were fed to four pens of roasters each, from 21 to 64 d of age. In exp. 2, grower and finisher turkey diets were formulated to contain 0, 22, 44, or 66% naked oats. The starter diet contained no naked oats. Two trials involving 964 birds were conducted. Treatment diets were fed to four pens of turkeys each, beginning at 21 d of age. Level of naked oats did not affect weight gain, feed efficiency or mortality of the roasters. The turkey poults consuming the 66% naked oats diet had significantly heavier 10-wk body weights and greater weight gains from 3 to 10 wk of age than those fed the other diets. In Trial 1, treatment had no significant effect on weight gains or feed efficiency for the finishing period (10–16 wk). In Trial 2, birds fed the 66% naked oats diet consumed significantly less feed than those fed the other diets, and had significantly heavier 12-wk body weights than birds fed the 22 and 44% naked oats diets. Treatment had no significant effect on weight gain or feed efficiency for the finishing period (10–12 wk). It appears that naked oats were a suitable feedstuff for the birds in this study. Key words: Naked oats, chicken roaster, turkey broiler, growth

Effect of 2-row or 6-row barley and a commercial enzyme preparation on growing-finishing broiler chickens from 3 to 6 weeks of age

A study was conducted to determine the efficacy of barley-based diets with or without a crude enzyme preparation for male broiler chickens from 3 to 6 wk of age. Treatments consisted of feeding grower and finisher diets based on two locally grown cultivars of barley, 2-row (unspecified cultivar) and 6-row (Leger) added at 0, 20, 40 and 60%, with 0 or 1000 mg commercial enzyme preparation/kg diet. The starter diet contained no barley. Enzyme addition to the 2-row barley-based diets resulted in significantly heavier 6 wk body weights compared to the non-supplemented diets and significantly improved feed efficiencies during the 5- to 6-wk period indicating an enzyme response in older birds. Level of 2-row barley did not have significant main effects on 6 wk body weight, weight gain, feed consumption, feed efficiency, mortality, or live grade, except for leg abnormalities. A significant linear contrast revealed increased percentage of leg abnormalities as the level of barley in the diet increased. Significant interactions were found between level of 2-row barley and enzyme addition for feed consumption and feed efficiency from 3 to 5 wk of age. Significant quadratic contrasts for level of barley within non-supplemented treatments indicated lower feed consumption of the 20 and 40% barley-fed birds than the 0 and 60% barley-fed birds during the 3-to 5-wk period. During the 5- to 6-wk period, feed consumption of the enzyme-supplemented diets increased linearly with percentage of barley in the ration. Neither level of 6-row barley nor enzyme addition to the 6-row barley diets had significant main effects on 6 wk body weight, weight gain, feed consumption, feed efficiency, or live grade. Significant interactions were found between level of 6-row barley and enzyme addition for 6 wk body weight, 3–6 wk weight gain and feed consumption for the 5–6 wk period. A significant quadratic contrast for level of barley within non-supplemented treatments revealed lower feed consumption of the 20 and 40% barley-fed birds compared to the 0 and 60% barley-fed birds during the 5–6 wk period. Thus, for the diets without glucanase, there was an effect of barley percentage which became apparent at different ages depending on the barley cultivar. As with the 2-row barley diets, there was a significant linear increase in feed consumption of the enzyme-supplemented diets as the level of 6-row barley in the diet increased during the 5–6 wk period. It appears from the results that the grower and finisher diets could contain up to 60% barley without being detrimental to growth but incidence of mortality or leg abnormality may increase somewhat. Enzyme addition improved feed efficiency for the 2-row barley diets, and erased the quadratic effects of barley level apparent when diets did not include β-glucanase. Key words: Barley, broiler chicken, enzyme, growth

Botulinum toxin treatment of spasticity in diplegic cerebral palsy: a randomized, double-blind, placebo-controlled, dose-ranging study

This study evaluated the efficacy and safety of three doses of botulinum toxin A (BTX-A; Dysport) in 125 patients (mean age 5.2 years, SD 2; 54% male)with dynamic equinus spasticity during walking. Participants were randomized to receive Dysport (10, 20, or 30 units/kg) or placebo to the gastrocnemius muscle of both legs. Muscle length was calculated from electrogoniometric measurements and the change in the dynamic component of gastrocnemius shortening at four weeks was prospectively identified as the primary outcome measure. All treatment groups showed statistically significant decreases in dynamic component compared with placebo at 4 weeks. Mean improvement in dynamic component was most pronounced in the 20 units/kg group, being equivalent to an increase in dorsiflexion with the knee extended at 19 degrees, and was still present at 16 weeks. The safety profile of the toxin appears satisfactory.

Introductory course in medical English and primary care for overseas doctors

This paper reports on a unique collaboration between two departments in the University of Edinburgh to develop and assess the value of a combined course in medical English and primary care, appropriate for young doctors from overseas who have a career intention in primary care.

Determination of the true metabolizable energy (TMEN) by roosters of feedstuffs made from seal by-products

TMEN values for various seal by-product feedstuffs were determined using roosters. Four samples of seal meal [seal meal 1991, seal meal 1992, seal meal 1994 (juveniles), seal meal 1994 (mixed ages)] and three samples of seal meat (oven-dried at 50 °C, oven-dried at 120 °C, and freeze-dried) were given to 16 roosters (30 g: precision fed) housed in individual wire cages. Total collection of excreta from a 48-h period was used to provide samples for analysis of gross energy, nitrogen, and dry matter content. TMEN results indicate variability in quality of the meals, associated with the different raw materials used to produce the seal meals as well as year of production. The TMEN values for the seal meals ranged from 3896 kcal kg−1 to 4621 kcal kg−1 with an average value of 4283 kcal kg−1. The crude protein content of the seal meals ranged from 64.2 to 67.6%, the crude fat content from 12.7 to 14.7%, the calcium content from 5.38 to 8.98% and the total phosphorus content from 3.16 to 4.79%. Oven-drying the seal meat at 120 °C significantly reduced TMEN (2643 kcal kg–1). The TMEN values for the freeze-dried and the low temperature oven-dried (50 °C) seal meat were not significantly different (4008 kcal kg–1 and 4013 kcal kg–1, respectively). Key words: True metabolizable energy, seal by-products, roosters, seal meal, seal meat, TMEN

Behind the scenes with genomics researchers

Although lab-coat genomics scientists are highly skilled and involved in pioneering work, few studies have examined their perceptions on what they do, and how they relate with others in interdisciplinary work. Recognizing that gap, we were curious to talk with scientists about their current work and positionalities related to the use of genomics for bioremediation. Using unstructured open-ended interviews and thematic analysis, we interviewed researchers with diverse genomics-related expertise. Emerging topics were grouped into two broad categories akin to Bronfenbrenner's nested developmental model: microsystem matters, comprising technical advances, barriers, and localized concerns; and macrosystem matters, exploring wider reflections and the philosophies of genomics and society. At the microsystem level, findings revealed differences of opinion about methodological steps, but there was agreement about the incompleteness of databases and the absence of established reference values. These two problems may not only impact a project's progress but also the ability to gauge success, affecting budgeting, human resource needs, and overall stress. At the macrosystem level, scientists voiced concerns about how different social groups perceive and accept genomics applications, as those tend to be viewed by lay persons as genetic interventions. Another focus was on how academic publication slows progress because it is orientated toward positive results while gaps in knowledge could be filled by publishing negative results or methodological barriers. This study underscores scientists' self-awareness within the genomics discipline, acknowledging how their beliefs and biases shape research outcomes. It illuminates critical reflections essential for navigating societal and scientific landscapes in genomics research.