Protein posttranslational modifications in health and diseases: Functions, regulatory mechanisms, and therapeutic implications

Protein posttranslational modifications (PTMs) refer to the breaking or generation of covalent bonds on the backbones or amino acid side chains of proteins and expand the diversity of proteins, which provides the basis for the emergence of organismal complexity. To date, more than 650 types of protein modifications, such as the most well-known phosphorylation, ubiquitination, glycosylation, methylation, SUMOylation, short-chain and long-chain acylation modifications, redox modifications, and irreversible modifications, have been described, and the inventory is still increasing. By changing the protein conformation, localization, activity, stability, charges, and interactions with other biomolecules, PTMs ultimately alter the phenotypes and biological processes of cells. The homeostasis of protein modifications is important to human health. Abnormal PTMs may cause changes in protein properties and loss of protein functions, which are closely related to the occurrence and development of various diseases. In this review, we systematically introduce the characteristics, regulatory mechanisms, and functions of various PTMs in health and diseases. In addition, the therapeutic prospects in various diseases by targeting PTMs and associated regulatory enzymes are also summarized. This work will deepen the understanding of protein modifications in health and diseases and promote the discovery of diagnostic and prognostic markers and drug targets for diseases.

The global syndemic of metabolic diseases in the young adult population: a consortium from the Global Burden of Disease 2000-2019

Funding Acknowledgements

Type of funding sources: None.

Background

A large proportion of premature deaths are related to metabolic diseases in the young adult population. We examined the global trends and mortality of metabolic diseases using estimates from the Global Burden of Diseases, Injuries and Risk Factors Study (GBD) 2019 in individuals aged below 40 years.

Methods

From 2000-2019, global estimates of prevalence, deaths, and disability-adjusted life years (DALYs) were described for metabolic diseases (type 2 diabetes mellitus [T2DM], hypertension, non-alcoholic fatty liver disease [NAFLD]). Global estimates were limited to mortality and DALYs for risk factors (hyperlipidemia and obesity). Subgroup analyses were performed based on sex, geographical regions and Socio-Demographic Index (SDI). Age-standardized prevalence, death, and DALYs were presented per 100,000 population with 95% uncertainty intervals (UI).

Findings

The prevalence for all metabolic diseases increased from 2000-2019, with the most pronounced increase in males and high SDI countries. In 2019, the highest age-standardised death rates were observed in hypertension (133·88 [121·25-155·73]; males, 160·13 [138·91-180·79]; females, 119·66 [102·33-136·86]), followed by obesity (62·59 [39·92-89·13]; males, 66·55 [39·76-97·21]; females, 58·14 [38·53-81·39]), hyperlipidemia (56·51 [41·83-73·62]; males, 67·33 [50·78-86·43]; females, 46·50 [32·70-62·38]), T2DM (18·49 [17·18-19·66]; males, 19·94 [18·50-21·32]; females, 17·30 [15·62-18·70]) and NAFLD (2·09 [1·61-2·60]; males, 2·38 [1·82-3·02]; females, 1·82 [1·41-2·27]). Similarly, obesity (1932·54 [1276·61-2639·74]) had the highest age-standardised DALYs, followed by hypertension (2885·57 [2580·75-3201·05]), hyperlipidemia (1207·15 [975·07-1461·11]), T2DM (801·55 [670·58-954·43]) and NAFLD (53·33 [40·73-68·29]). Mortality rates decreased over time in hyperlipidemia (-60%), hypertension (-47%), NAFLD (-31%) and T2DM (-20%), but not in obesity (107% increase). The highest metabolic-related mortality was observed in the Eastern Mediterranean and low SDI countries.

Conclusion

The growing prevalence of metabolic diseases, increasing obesity-related mortality trends, and the sex-regional-socioeconomic disparities evident in young adulthood, present the concerning global burden of metabolic diseases now and in the years ahead.

Higher risk of adverse cardiovascular outcomes in women with type 2 diabetes mellitus: an umbrella review of systematic reviews

Funding Acknowledgements

Type of funding sources: None.

Background

Previous studies have shown that females with type 2 diabetes mellitus (T2DM) may have an excess mortality risk compared to males. Furthermore, other studies have reported sex differences in managing cardiovascular risk factors, such as controlling hypertension and hypercholesterolemia.

Purpose

With the growing evidence from systematic reviews examining the sex differences in cardiovascular outcomes for patients with T2DM, an umbrella review is an essential next step to synthesising and assessing the strength of the available evidence.

Methods

Medline and Embase were searched from inception till 7th August 2022 for systematic reviews and meta-analyses studying the effects of sex on cardiovascular outcomes in T2DM patients. Results from reviews were synthesised with a narrative synthesis, with a tabular presentation of findings and forest plots for reviews that performed a meta-analysis. AMSTAR 2 tool was used to assess the methodological quality of included reviews, while the GRADE assessment was used to assess the quality of evidence for outcomes.

Results

A total of 28 studies evaluating sex differences in cardiovascular outcomes were included. Females with T2DM had a higher risk of developing coronary heart disease (CHD; RRR 1.52, 95%CI 1.32–1.76, p<0.001), acute coronary syndrome (ACS; RRR 1.38, 95%CI 1.25–1.52, p<0.001), and heart failure (RRR 1.09, 95%CI 1.05–1.13, p<0.001) than males. In terms of mortality outcomes, females had a higher risk of all-cause mortality (RRR 1.13, 95%CI 1.07–1.19, p<0.001), cardiac mortality (RRR 1.49, 95%CI 1.11–2.00, p=0.009) and CHD mortality (RRR 1.44, 95%CI 1.20–1.73, p<0.001) as compared to males. In patients undergoing percutaneous coronary intervention, females reported higher odds of MACE (OR 1.49, 95%CI 1.07–2.07, p=0.020) and all-cause mortality (OR 1.71, 95%CI 1.46–2.00, p<0.001) compared to males. Females in Asia (RRR 1.12, 95%CI 1.03–1.21, p=0.006) and North America (RRR 1.10, 95%CI 1.08–1.12, p<0.001) were at increased risk of all-cause mortality while females in Western countries had an increased risk for cardiac death (RRR 1.84, 95%CI 1.45–2.32, p<0.001) compared to males. Six reviews were rated as high in quality; eight reviews were rated as moderate, and fourteen reviews were rated as low in quality. Regarding the quality of outcomes, all outcomes in non-interventional studies had a moderate quality of evidence, while all outcomes in interventional studies achieved a high quality of evidence.

Conclusions

This umbrella review evaluated the quality of meta-analyses and demonstrated that females with T2DM have a higher risk of cardiovascular outcomes than their male counterparts. Future studies examining the sex differences in outcomes should attempt to address the heterogeneity and epidemiological factors for a better quality of evidence. Policymakers should consider sex-specific differences in implementing effective tailored strategies to tackle T2DM.

Effects of epicardial adipose tissue volume and thickness assessed by computed tomography and echocardiography on cardiovascular and cerebrovascular outcomes: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Epicardial adipose tissue (EAT) has garnered attention as a potential imaging biomarker for the risk stratification of cardiovascular diseases (CVD). However, the prognostic utility of EAT due to inter-ethnic differences and imaging modality (computed tomography (CT) or transthoracic echocardiography (TTE)) remains undetermined.

Purpose

To evaluate the effect of EAT volume and thickness on cardiovascular and cerebrovascular outcomes. We also aim to compare the prognostic utility between CT volumetric and TTE thickness quantification; and provide consolidated data on the heterogeneity in EAT measurements across different ethnic groups.

Methods

Medline and Embase databases were searched from inception till 16 May 2022 for studies that measured EAT volume or thickness of adult patients at baseline and reported follow-up data on outcomes of interest. Outcomes included MACE, all-cause mortality, cardiac death, myocardial infarction (MI), coronary revascularisation, atrial fibrillation (AF), and stroke. Statistical analyses were conducted on Review Manager 5.4.1 to obtain unadjusted and adjusted hazard ratios (HR) and odds ratios (OR) with the results presented on forest plots.

Results

Twenty-nine studies comprising 19709 patients were included in our analysis. Increased EAT thickness and volume were associated with higher risks of MACE (adjusted HR [aHR] 1.46, 95%CI 1.25–1.71, p<0.001), cardiac death (OR 2.53, 95%CI 1.17–5.44, p=0.020), MI (OR 2.63, 95%CI 1.39–4.96, p=0.003), coronary revascularisation (OR 2.99, 95%CI 1.64–5.44, p<0.001), AF (aOR 4.04, 95%CI 3.06–5.32, p<0.001), and stroke (HR 1.02, 95%CI 1.01–1.03, p<0.001). CT-volumetric quantification of EAT conferred a larger MACE risk (aHR 1.79, 95%CI 1.47–2.17, p<0.001) compared to TTE thickness quantification (aHR 1.20, 95%CI 1.09–1.32, p<0.001). Studies originating from North America (HR 1.91, 95%CI 1.26–2.89, p=0.002) and Asia (HR 1.60, 95%CI 1.09–2.36, p=0.020) demonstrated a significantly higher risk of MACE with increased EAT thickness and volume. However, this significance was not seen in European studies (HR 1.48, 95%CI 0.99–2.20, p=0.060). Subgroup differences were also noted across the studies’ countries of origin when analysing the association of EAT and MI (p=0.020). European studies reported a higher magnitude of MI risk associated with higher EAT thickness and volume (OR 5.28, 95%CI 2.34–11.95, p<0.001) as compared to Asian studies (OR 1.75, 95%CI 1.05–2.92, p=0.030). No differences were noted across other outcomes in the subgroup comparisons by geographical region and between CT and TTE quantification of EAT.

Conclusion

The utility of EAT as an imaging biomarker for predicting and prognosticating CVD is promising. Future efforts to harmonise the EAT parameter thresholds, based on the type of imaging modality and the target population’s ethnic characteristics, will be the next important step before including EAT in CVD prediction models.

Prognostically distinct phenotypes of metabolic health beyond obesity in aortic stenosis

Background

Whilst current evidence are in favour of metabolic health and non-obesity in the reduction of incident cardiovascular disease, little is known regarding the prognosis across the metabolic phenotypes once cardiovascular disease occurs. This study examined the prognosis of patients with significant aortic stenosis (AS) based on the presence of metabolic health and obesity.

Methods

This retrospective cohort on consecutive patients presenting with moderate-to-severe AS to a tertiary hospital between 2010 and 2015. Patients were allocated into 4 groups based on obesity and metabolic health: metabolically healthy obese (MHO), metabolically healthy non-obese (MHNO), metabolically unhealthy obese (MUO) and metabolically unhealthy non-obese (MUNO). Metabolic health was defined in accordance to Program Adult Treatment Panel III criteria. The primary outcome was all-cause mortality. Cox regression examined independent associations between mortality and metabolic phenotypes, adjusting for aortic valve area, ejection fraction, age, sex, chronic kidney disease and AVR as a time-dependent covariate.

Results

Of 727 patients, the majority (51.6%) were MUNO, followed by MUO (32.7%), MHNO (11.4%), and MHO (4.3%). MHNO had the highest mortality (43.0%), followed by the MUNO (37.5%), MUO (30.0%) and MHO (6.9%) groups (p=0.001). Compared to MHNO, MHO (HR 0.159, 95% CI 0.038–0.668, p=0.012) and MUO (HR 0.614, 95% CI 0.403–0.937, p=0.024) were independently associated with lower all-cause mortality rates, after adjusting for confounders. In obese patients, metabolic health had favourable survival compared to metabolically unhealthy (p=0.015), but this protective impact of metabolic health was not observed in overweight or normal weight individuals. Obesity had favourable survival compared to overweight and normal weight, in both metabolically health (p=0.002) and unhealthy (p=0.007) patients,

Conclusion

MHO patients with AS have the most favourable prognosis whilst the seemingly healthy MHNO group had the worst survival. There should be a paradigm shift towards prioritising metabolic health rather than weight reduction in patients with significant AS.

Funding Acknowledgement

Type of funding sources: None.

Practice-based differences in paediatric discoid lupus erythematosus

BACKGROUND

Children with discoid lupus erythematosus (DLE) are at risk for disfigurement and progression to systemic lupus erythematosus (SLE). Consensus is lacking regarding optimal care for children with DLE.

OBJECTIVES

The aim of this study was to compare practice patterns among paediatric dermatologists/rheumatologists treating paediatric DLE.

METHODS

An online survey was sent to 292 paediatric rheumatologists in the Childhood Arthritis and Rheumatology Research Alliance and 200 paediatric dermatologists in the Pediatric Dermatology Research Alliance. Consensus was defined as ≥ 70% agreement.

RESULTS

Survey response rates were 38% (76 of 200) for dermatology and 21% (60 of 292) for rheumatology. Both specialties agreed that screening labs should include complete blood counts with differential, urinalysis, complement levels, erythrocyte sedimentation rate, antinuclear antibody and other autoantibodies, hepatic function and renal function/electrolytes. Both specialties agreed that arthritis or nephritis should prompt intensified evaluation for SLE. No other patient features achieved consensus as disease-modifying risk factors. Hydroxychloroquine was agreed upon as first-line systemic therapy, but consensus was lacking for second- or third-line treatment.

CONCLUSIONS

We found few areas of consensus and significant practice differences between paediatric dermatologists and rheumatologists treating DLE. Knowledge gaps include risk factors for SLE, optimal screening and treatment of refractory skin disease.

Low-molecular-weight heparin biosimilars: potential implications for clinical practice. Australian Low-Molecular-Weight Heparin Biosimilar Working Group (ALBW)

A working group of clinicians and scientists was formed to review the clinical considerations for use of low-molecular-weight heparin (LMWH) biosimilars. LMWH are biological molecules of significant complexity; the full complexity of chemical structure is still to be elucidated. LMWH biosimilars are products that are biologically similar to their reference product and rely on clinical data from a reference product to establish safety and efficacy. The complex nature of LMWH molecules means that it is uncertain whether a LMWH biosimilar is chemically identical to its reference product; this introduces the possibility of differences in activity and immunogenicity. The challenge for regulators and clinicians is to evaluate the level of evidence required to demonstrate that a LMWH is sufficiently similar to the reference product. The consensus opinion of the working group is that prior to clinical use a LMWH biosimilar should have proven efficacy and safety, similar to the reference product with prospective studies, which should be confirmed with a proactive post-marketing pharmacovigilance programme.

SMARCB1/INI1 maternal germ line mosaicism in schwannomatosis

Schwannomatosis is characterized by the development of multiple schwannomas of the nervous system, but without the occurrence of vestibular schwannomas. Most cases of schwannomatosis are thought to be sporadic, representing the first case in a family due to a new mutation in the causative gene. We recently identified SMARCB1/INI1 as a schwannomatosis-predisposing gene. Here, we analyzed this gene in a schwannomatosis family with two affected children, but with clinically unaffected parents. Both affected individuals carried a constitutional SMARCB1 mutation, c.1118+ 1G>A, that changes the donor splice site sequence of intron 8, causing skipping of exon 8 and resulting in the in-frame deletion of 132 nucleotides in the transcript. The mutation was not evident in constitutional DNA of the parents. Haplotyping revealed that the chromosome 22 segment that carries the mutant SMARCB1 allele originated from the mother. She transferred the same chromosome 22 segment, however, with a wild-type SMARCB1 copy, to a third unaffected child. Our findings indicate that the mother is germ line mosaic for the SMARCB1 mutation. In conclusion, our study shows for the first time that germ line mosaicism may occur in schwannomatosis, which has implications for genetic counseling in this disease.

Use of the newborn screening card to define cause of death in a 12-year-old diagnosed with epilepsy

Post-mortem investigation of sudden death in young people frequently reveals no overt cause for the death. Full investigation is hampered if tissue or blood is not retained for DNA analysis. We report a post mortem molecular diagnosis of long QT syndrome in a 12-year-old boy diagnosed with epilepsy who died suddenly playing sport. The DNA was extracted from an archived blood spot on his newborn screening ('Guthrie') card, which had been taken from him at 6 days of age. A missense mutation was detected in exon 5 of the KCNQ1 gene; R243C (835C > T), associated with long QT type 1. The same mutation was found in the mother (who now takes effective preventative therapy), but not in the sib who has now been reassured that she is not at risk of sudden death.

Molecular and cultural analysis of the microflora associated with endodontic infections

Cultural studies have indicated that a subset of the oral microflora is responsible for endodontic infections. Approximately 50% of oral bacteria are unculturable, so it is likely that currently unknown bacteria are present in such infections. In this study, cultural and molecular analyses were performed on the microflora in aspirate samples collected from 5 infected root canals. 16S rDNA sequences from 261 isolates and 624 clones were identified by comparison with database sequences. Sixty-five taxa were identified, of which 26 were found by the molecular method alone. A mean of 20.2 taxa was found in each sample. A new species of Dialister was the only organism present in all 5 samples. Twenty-seven novel taxa were detected, 18 of which belonged to the phylum Firmicutes and 8 to Bacteroidetes. Culture-independent, molecular analysis has revealed a more diverse microflora associated with endodontic infections than that revealed by cultural methods alone.

Detection of sequence variations in the adenomatous polyposis coli (APC) gene using denaturing high-performance liquid chromatography

We have evaluated the usefulness of denaturing high performance liquid chromatography (dHPLC) for scanning the adenomatous polyposis coli (APC) gene for point mutations, small deletions, and insertions. Our assay consists of 28 sets of primers to amplify the 15 exons of the APC gene. All PCR reactions were amplified simultaneously using the same reaction conditions in a 96-well format and then analyzed by dHPLC, using empirically determined optimum temperatures for partial fragment denaturation. Previously studied DNA specimens from 47 familial adenomatous polyposis (FAP) patients were analyzed by dHPLC and all mutations were correctly identified and confirmed by sequence analysis. This approach identified a single-base substitution in exon 6 and a 2-bp insertion in exon 15 that initially had not been detected by single-strand conformational polymorphism (SSCP) analysis. A novel mutation in exon 15 of the APC gene, 2065delG (codon 689) that had previously been undetected by the protein truncation test (PTT) was also identified by dHPLC. We present our validation studies of dHPLC technology for APC gene analysis in terms of sensitivity and specificity and compare it to current standard scanning technologies including PTT, SSCP, and conformational sensitive gel electrophoresis (CSGE).

Treatment with the novel anti-angiogenic agent PI-88 is associated with immune-mediated thrombocytopenia

BACKGROUND

The novel molecule PI-88 is a highly sulfonated oligosaccharide which inhibits heparanase activity and competes with heparan sulfate binding of growth factors such as FGF and VEGF. Preclinical data demonstrates that PI-88 inhibits angiogenesis and has anti-metastatic effects. The aim of this phase I study was to determine the recommended dose and toxicity profile of PI-88.

PATIENTS AND METHODS

PI-88 was given intravenously in increasing duration of administration (0.57 mg/kg for 2 h, 0.57 mg/kg/day for 1 day, 4, 7 and 14 consecutive days) and then increasing dose for 14 consecutive days (1.14 mg/kg/day and 2.28 mg/kg/day) in patients with advanced malignancies until dose-limiting toxicity (DLT) was observed. Fourteen assessable patients with advanced malignancies received PI-88 intravenously.

RESULTS

DLT was thrombocytopenia. The thrombocytopenia appeared to be immunologically mediated with the development of anti-heparin platelet factor 4 complex antibodies. There were no other significant toxicities. At the final dose and schedule (2.28 mg/kg/day for 14 days), there was limited evidence of biological activity as measured by the surrogate marker activated partial thromboplastin time (APTT), although two patients had stabilisation of disease.

CONCLUSIONS

In conclusion, PI-88 at a dose of 2.28 mg/kg/day for 14 days resulted in dose-limiting thrombocytopenia which appeared to be immune related. Limited evidence of biological activity was noted. Alternate scheduling and routes of administration are now being explored.

Compound heterozygosity at the FMR1 gene

Individuals affected with Fragile X syndrome are usually characterized at the DNA level by the presence of at least 200 CGG repeats in the 5' untranslated region of the FMR1 gene; this number of repeats is defined as a full mutation. Repeats that number 50-200 usually define those with premutations and are termed unaffected carriers. We report here a compound heterozygous female who carried CGG repeats in the FMR1 gene that fall within the premutation and full mutation ranges. The former appears to have been inherited from the father, whereas the latter is an expansion of the premutation carried by the proband's mother. Therefore, the offspring of the proband will carry a significant risk of being affected with Fragile X syndrome, and the paternal uncle and any cousins should be counselled for being at risk for this syndrome.

Clinical & genetic analysis of four patients with distal upper limb spinal muscular atrophy

BACKGROUND & OBJECTIVES

Distal upper limb spinal muscular atrophy (SMA) is an uncommon segmental variant of SMA. The condition is usually sporadic, affects males more often than females, and manifests late in the second decade of life, remaining confined to the upper limbs. We examined four patients with this form of SMA in order to determine if they carried homozygous deletion mutations in the survival motor neuron (SMN) or neuronal apoptosis inhibitory protein (NAIP) genes that underlie proximal SMA.

METHODS

The four patients with distal upper limb SMA were analysed clinically, electrophysiologically and biochemically. Genomic DNA from each of the patients was analysed by restriction enzyme digestion of polymerase chain reaction (PCR) amplification products, as well single stranded conformation polymorphism (SSCP), to detect deletion events of selected exons of the SMN and NAIP genes.

RESULTS

The clinical phenotype of the four patients, together with the biochemical and electrophysiological studies, confirmed a diagnosis of distal upper limb SMA. The molecular studies excluded homozygous deletion mutations in these patients as causative of their phenotype.

INTERPRETATION & CONCLUSION

The genetic component underlying distal upper limb SMA appears not to involve mutations that are common in proximal SMA patients. It is possible that genes other than SMN and NAIP may be involved, while somatic mosaicism of SMN gene mutations could be implicated in the segmental nature of distal upper limb SMA.

Eos and pegasus, two members of the Ikaros family of proteins with distinct DNA binding activities

Members of the Ikaros family of transcription factors, Ikaros, Aiolos, and Helios, are expressed in lymphocytes and have been implicated in controlling lymphoid development. These proteins contain two characteristic clusters of zinc fingers, an N-terminal domain important for DNA recognition, and a C-terminal domain that mediates homo- and heterotypic associations between family members. The conservation of these domains is such that all three proteins recognize related DNA sequences, and all are capable of dimerizing with other family members. Here we describe two additional Ikaros family proteins, Eos and Pegasus. Eos is most highly related to Helios and shares its DNA binding and protein association properties. Pegasus is related to other Ikaros proteins in its C-terminal dimerization domain but contains a divergent N-terminal zinc finger domain. Pegasus self-associates and binds to other family members but recognizes distinct DNA-binding sites. Eos and Pegasus repress the expression of reporter genes containing their recognition elements. Our results suggest that these proteins may associate with previously described Ikaros family proteins in lymphoid cells and play additional roles in other tissues.

Hierarchical mutation screening protocol for the BRCA1 gene

The identification of mutations in the BRCA1 gene poses difficulties in achieving a screening outcome that satisfies the twin needs of speed and accuracy. These needs must also take into account the patient's family history and the statistical evaluation of the probability of detecting a mutation. Given the above, we present here a hierarchical mutation screening strategy that comprises two tiers: first, multiplex heteroduplex and exon 13 duplication analysis; second, exon amplification and direct sequencing using a 96-well tray format. The advantages of this strategy are two-fold: first, the division of analytical tools in order to achieve low and high-resolution mutation screening, respectively; second, a streamlined sequencing approach that leads to a sensitive and rapid assay that reduces labor costs and handling errors. The success of this approach is shown by the identification of a novel deletion mutation in exon 14 of the BRCA1 gene, which was not detected by the more conventional protein truncation assay due to the small size of the predicted truncated protein.

The relationship of magnetic source imaging to ictal electrocorticography in a neuronavigational workspace

Magnetic source imaging (MSI) registers magnetoencephalographic (MEG) activity to a three-dimensional MRI volume. State-of-the-art MSI allows concurrent whole head coverage, but is practically restricted to interictal recording. However, the purpose of the presurgical evaluation of epileptic patients, in which MSI is playing an increasing role, is the elucidation of the ictal epileptogenic focus. The manner in which interictal MSI activity relates to the ictal focus has not yet been adequately examined. To facilitate this analysis, we are developing techniques to precisely coregister MSI to the ictal onset zone as defined by extraoperative intracranial grid/strip monitoring. The neuronavigational workspace is a convenient area in which to precisely coregister these (and other) imaging and physiological data sets.

Magnetoencephalographic patterns of epileptiform activity in children with regressive autism spectrum disorders

BACKGROUND

One-third of children diagnosed with autism spectrum disorders (ASDs) are reported to have had normal early development followed by an autistic regression between the ages of 2 and 3 years. This clinical profile partly parallels that seen in Landau-Kleffner syndrome (LKS), an acquired language disorder (aphasia) believed to be caused by epileptiform activity. Given the additional observation that one-third of autistic children experience one or more seizures by adolescence, epileptiform activity may play a causal role in some cases of autism.

OBJECTIVE

To compare and contrast patterns of epileptiform activity in children with autistic regressions versus classic LKS to determine if there is neurobiological overlap between these conditions. It was hypothesized that many children with regressive ASDs would show epileptiform activity in a multifocal pattern that includes the same brain regions implicated in LKS.

DESIGN

Magnetoencephalography (MEG), a noninvasive method for identifying zones of abnormal brain electrophysiology, was used to evaluate patterns of epileptiform activity during stage III sleep in 6 children with classic LKS and 50 children with regressive ASDs with onset between 20 and 36 months of age (16 with autism and 34 with pervasive developmental disorder-not otherwise specified). Whereas 5 of the 6 children with LKS had been previously diagnosed with complex-partial seizures, a clinical seizure disorder had been diagnosed for only 15 of the 50 ASD children. However, all the children in this study had been reported to occasionally demonstrate unusual behaviors (eg, rapid blinking, holding of the hands to the ears, unprovoked crying episodes, and/or brief staring spells) which, if exhibited by a normal child, might be interpreted as indicative of a subclinical epileptiform condition. MEG data were compared with simultaneously recorded electroencephalography (EEG) data, and with data from previous 1-hour and/or 24-hour clinical EEG, when available. Multiple-dipole, spatiotemporal modeling was used to identify sites of origin and propagation for epileptiform transients.

RESULTS

The MEG of all children with LKS showed primary or secondary epileptiform involvement of the left intra/perisylvian region, with all but 1 child showing additional involvement of the right sylvian region. In all cases of LKS, independent epileptiform activity beyond the sylvian region was absent, although propagation of activity to frontal or parietal regions was seen occasionally. MEG identified epileptiform activity in 41 of the 50 (82%) children with ASDs. In contrast, simultaneous EEG revealed epileptiform activity in only 68%. When epileptiform activity was present in the ASDs, the same intra/perisylvian regions seen to be epileptiform in LKS were active in 85% of the cases. Whereas primary activity outside of the sylvian regions was not seen for any of the children with LKS, 75% of the ASD children with epileptiform activity demonstrated additional nonsylvian zones of independent epileptiform activity. Despite the multifocal nature of the epileptiform activity in the ASDs, neurosurgical intervention aimed at control has lead to a reduction of autistic features and improvement in language skills in 12 of 18 cases.

CONCLUSIONS

This study demonstrates that there is a subset of children with ASDs who demonstrate clinically relevant epileptiform activity during slow-wave sleep, and that this activity may be present even in the absence of a clinical seizure disorder. MEG showed significantly greater sensitivity to this epileptiform activity than simultaneous EEG, 1-hour clinical EEG, and 24-hour clinical EEG. The multifocal epileptiform pattern identified by MEG in the ASDs typically includes the same perisylvian brain regions identified as abnormal in LKS. When epileptiform activity is present in the ASDs, therapeutic strategies (antiepileptic drugs, steroids, and even neurosurgery) aimed at its control can lead to a significa

hFOG-2, a novel zinc finger protein, binds the co-repressor mCtBP2 and modulates GATA-mediated activation

We have identified a novel human zinc finger protein, hFOG-2, which is related to but distinct from the murine transcription factor Friend-of-GATA-1 (mFOG-1). The hFOG-2 gene was initially detected in K562 cells using a polymerase chain reaction approach with degenerate primers corresponding to zinc finger regions of mFOG-1. A murine homologue of hFOG-2 was also identified in the mouse expressed sequence tag data banks, indicating that a family of FOG genes exists in mammals. hFOG-2 appears to be widely expressed, while mFOG-1 is expressed primarily in erythroid and megakaryocytic cells and plays a fundamental role in the development of these lineages. Sequencing of the full-length hFOG-2 cDNA indicates that the interaction domains for transcription factors GATA-1 and mCtBP2 are both conserved and we have shown that this new FOG protein also physically interacts with these factors. We have demonstrated that hFOG-2, like mFOG-1, can act in concert with GATA-1 to activate gene expression from the p45 NF-E2 promoter region, but that it can also act to repress GATA-mediated activation of additional reporter constructs. Finally, we have identified a repression domain in hFOG-2 and show that repression is dependent upon the integrity of the mCtBP2 interaction motif Pro-Ile-Asp-Leu-Ser.

Cord blood is better than bone marrow for generating megakaryocytic progenitor cells

Thrombocytopenia remains an important problem for patients post high-dose chemotherapy and hematopoietic stem cell transplantation. The study of megakaryocytes, the direct precursors of platelets, has been hampered by their relatively low frequency in hematopoietic tissues. In an attempt to obtain a large number of functional megakaryocytic cells, we established a serum-free culture system to grow megakaryocytic progenitor cells derived from normal human bone marrow (BM) and cord blood (CB). Highly purified (purity >95%) CD34+ cells were obtained using magnetic cell sorting (MACS) followed by fluorescence activated cell sorting (FACS). The cells were cultured in a serum-free culture system for 3 weeks in the presence of a single dose of MGDF (50 ng/mL). On days 0, 5, 8, 12, 14, 18, and 21 of culture, the cellularity and morphology were examined. Megakaryocytic cells were monitored by detecting the expression of GPIIIa (CD61), GPIIb/IIIa (CD41) and GPIb (CD42b), and the distribution of megakaryocyte (MK) ploidy was analyzed by two-color flow cytometry. MGDF alone induced maximal nucleated cell expansion at day 14, resulting in a 38.20+/-10.47-fold increase in cell number for CB and a 5.08+/-1.30-fold increase in cell number for BM. On day 14 of the culture, the percentage of CD41-/CD14- cells derived from CB reached 73.54%+/-6.01% giving an absolute number of CD41+/CD14- cells of 27.25+/-2.23 x 10(4)/mL (27,250-fold increase), whilst the percentage of CD41+/CD14- cells derived from BM was only 29.21%+/-5.63% with an absolute number of 1.36+/-0.26 x 10(4)/mL (680-fold increase). Increased expression of GPIIIa occurred the earliest in culture, followed by GPIIb/IIIa, and then GPIb. The majority (81.6%-92.6%) of megakaryocytes (CD41+ cells) on day 14 of culture were 2N, although we did detect some 4N, 8N and greater ploidy cells. In conclusion, CD34+ cells stimulated by MGDF alone generated highly enriched MK progenitor cells at day 14 of serum-free culture. CB stem and progenitor cells have a greater proliferative response to MGDF alone than those derived from BM and may, therefore, prove to be a better source of cells for MK expansion.

Expansion and shrinkage of central nervous system tumor coinciding with human growth hormone therapy: case report

OBJECTIVE AND IMPORTANCE

The influence of human growth hormone (hGH) therapy on the recurrence rates of childhood central nervous system tumors is controversial. Because growth hormone has the ability to increase cell proliferation, it is recommended that hGH therapy wait until central nervous system lesions are inactive and antitumor therapy complete, usually 1 to 2 years.

CLINICAL PRESENTATION

We report the enlargement and decrease in size of a hypothalamic pilocytic astrocytoma in a 12-year-old boy after two trials of hGH. Partial resection and radiation of the tumor were performed at 3 years of age, with no change noted over the next 9 years. His height was less than the 5th centile with midparental height at the 90th to 95th centiles. Growth velocity was 3.3 cm/yr. Bone age was normal and there were no signs of puberty. There was no GH response to clonidine and L-dopa testing.

INTERVENTION

Volume measurements were performed on gadolinium enhanced tumor images. Growth rate increased to 11.7 cm and the tumor volume increased 230% over the 12 months of hGH therapy. Significant tumor shrinkage (42%) and growth deceleration occurred within the 3 month interval of stopping hGH. Tumor volume again increased (134%) and decreased (22%) after restarting and then stopping hGH. No evidence of tumor necrosis or alteration in ventricular size was found. The patient was asymptomatic.

CONCLUSION

These observations indicate that tumor size change is associated with the metabolic response to hGH therapy. It is unclear whether the volume increase represents altered blood-brain or selective blood-tumor barrier permeability, growth factor receptors, and/or tumor cell growth.

Iron(II)/reductant(DH2)-induced activation of dioxygen for the hydroxylation and ketonization of hydrocarbons; mimics for the cytochrome P-450 hydroxylase/reductase system

Several metal complexes [(FeII(DPAH)2 (DPAH2 = 2,6-dicarboxyl pyridine), FeII(PA)2 (PAH = picolinic acid), FeII(bpy)2(2+), FeII(OPPh3)4(2+), (Cl8TPP)FeIIIX (X = Cl, OH, SCH2Ph) [Cl8TPP = tetrakis (2,6-dichlorophenyl)porphyrin], (TPP) FeIIICl (TPP = tetraphenylporphyrin), and CuI(tpy)2+ (typ = 2,2'-6,2"-terpyridine)] in combination with one of several reductants [DH2; PhNHNHPh (mimic of dihydroflavin), PhNHNH2, ascorbic acid (H2asc), and PhCH2SH (model ligand for cysteine residue)] catalytically activate O2 (1 atm) for the hydroxylation of saturated hydrocarbons (e.g. c-C6H12-->c-C6H11OH). This chemistry closely parallels that of cytochrome P-450 proteins, and both appear to involve a Fenton-like reactive intermediate), [LxFeOOH(DH)]. With cyclohexane as the substrate the dominant product is its ketone (as well as significant amounts of its hydroperoxide). 1,4-Cyclohexadiene (with two double-allylic carbon centers) undergoes dehydrogenation to give benzene, but also yields substantial amounts of phenol via ketonization of an allylic carbon. The 1:1 FeII(bpy)2(2+)/(PhNHNH2 or H2asc), FeII(PA)2/H2asc, and (Cl8TPP)FeIIICl/PhNHNH2 combinations initiate the autoxidation of 1,4-cyclohexadiene with turnover numbers (moles of product per mole of reductant) from 71 to 26, respectively (alpha-tocophenol reduces the turnover numbers by 20-80%). With respect to aerobic biology, the present results indicate that dysfunctional transition metals (degradation products of metalloproteins) in combination with biological reductants activate O2 for reaction with organic substrates. The level of activation is similar to that for Fenton reagents and cytochrome P-450 hydroxylases. Hence, dysfunctional transition metals, reductants, and O2 are a hazardous combination within a biological matrix.

MR of the spine in Guillain-Barré syndrome

MR examination of the spine after injection of gadopentetate dimeglumine showed enhancement of the cauda equina in a case of Guillain-Barré syndrome. These MR observations may help confirm the diagnosis of Guillain-Barré syndrome.

Amrinone--a new inotropic agent in chronic resistant congestive cardiac failure

A patient with severe cardiac failure due to idiopathic congestive cardiomyopathy resistant to conventional therapy, responded to amrinone, a new non-glycosidic non-catecholamine positive inotropic agent. Amrinone produced significant haemodynamic improvement during both intravenous and oral administration. Thrombocytopaenia, however, was induced, necessitating cessation of the drug. Amrinone is a promising, orally effective inotropic agent for patients with refractory congestive cardiac failure, but is limited to its tendency to cause thrombocytopaenia.