Arnold-Chiari Malformations in Pregnancy and Labor: Challenges and Management Strategies

Arnold-Chiari malformations (ACMs) present unique challenges in pregnancy and labor, requiring a comprehensive understanding and multidisciplinary approach to care. This review article provides an overview of ACMs, including their definition, classification, and prevalence. The challenges in diagnosing ACMs during pregnancy, the available imaging modalities, and screening recommendations are discussed. The impact of ACMs on maternal health, fetal development, and the management strategies employed during pregnancy and labor are explored. Emphasis is placed on the importance of a multidisciplinary approach involving neurologists, obstetricians, and other specialists. Medical management options for symptom relief, surgical interventions, and anesthetic considerations during labor and delivery are also addressed. The importance of postpartum care, breastfeeding considerations, and long-term follow-up for women with ACMs who desire future pregnancies are highlighted. Finally, areas for further research and advancements in ACM management are identified. By improving our understanding and management of ACMs in pregnancy and labor, healthcare professionals can optimize care and improve outcomes for mothers and babies affected by this condition.

Extracorporeal Membrane Oxygenation (ECMO): A Lifeline for Pregnant and Postpartum Women

Extracorporeal membrane oxygenation (ECMO) is a life-saving technology that temporarily supports the heart and lungs in critical care situations. This review article examines the role of ECMO as a lifeline for pregnant and postpartum women facing severe maternal and fetal conditions. The review begins with an overview of the physiology and pathophysiology of ECMO, including its procedure and how it supports cardiopulmonary function. Unique considerations specific to pregnant and postpartum women, such as physiological changes during pregnancy, risks and complications associated with ECMO, and the need to balance maternal and fetal considerations, are discussed. The indications for ECMO in this population are explored, including common maternal indications such as cardiogenic shock, acute respiratory distress syndrome (ARDS), pulmonary embolism, and eclampsia, as well as fetal indications such as fetal distress, hypoxic-ischemic encephalopathy (HIE), and twin-to-twin transfusion syndrome (TTTS). The challenges and considerations in ECMO for pregnant and postpartum women, including ethical considerations and the decision-making process, are highlighted. The review further explores the multidisciplinary care and collaborative approach required, emphasizing the importance of a specialized ECMO team and collaboration between obstetricians, neonatologists, cardiologists, and other specialists. Additionally, patient selection, pre-ECMO assessment, and planning strategies are discussed. The review evaluates existing literature and studies on ECMO in pregnant and postpartum women, analyzing survival rates and maternal and fetal outcomes and comparing different ECMO modalities and strategies. Future directions and research opportunities are presented, including emerging technologies, areas for further research and clinical trials, and improved patient selection and management strategies. The conclusion emphasizes the importance of ECMO as a lifeline for pregnant and postpartum women and the potential impact on maternal and fetal health. The review highlights the need for ongoing research and advancements in ECMO to optimize outcomes and improve care for this unique and vulnerable patient population.

Pyoderma Gangrenosum: A Challenging Cutaneous Manifestation in Dubowitz Syndrome

Pyoderma gangrenosum (PG) is a challenging cutaneous manifestation associated with Dubowitz syndrome, a rare genetic disorder characterized by multiple congenital anomalies, developmental delay, and distinctive facial features. This review article aims to provide a comprehensive overview of the association between Dubowitz syndrome and pyoderma gangrenosum, emphasizing the clinical presentation, challenges in diagnosis and management, and potential underlying mechanisms. A comprehensive literature search was conducted to gather relevant studies, and inclusion and exclusion criteria were applied to select appropriate articles. The association between Dubowitz syndrome and pyoderma gangrenosum has been documented in reported cases and studies. Clinical characteristics of Pyoderma gangrenosum in Dubowitz syndrome include painful necrotic ulcers with undermined borders. Diagnosing pyoderma gangrenosum in the context of Dubowitz syndrome can be challenging due to the overlapping clinical features and complexities associated with the syndrome. Managing pyoderma gangrenosum involves a multidisciplinary approach, with general principles of wound care, systemic therapy, and pain management. Specific considerations for treating pyoderma gangrenosum in Dubowitz syndrome include collaboration among specialists and careful monitoring. Future directions for management include further research to understand the underlying mechanisms and develop targeted therapies. Recognizing and addressing pyoderma gangrenosum in Dubowitz syndrome is crucial for optimal patient care. This review enhances awareness among healthcare professionals and provides insights for improving diagnosis, management, and treatment outcomes for individuals with this challenging combination of conditions.

Exploring the Role of Vitamin D in Atherosclerosis and Its Impact on Cardiovascular Events: A Comprehensive Review

This review explores the role of vitamin D in atherosclerosis and its impact on cardiovascular events. Atherosclerosis, a chronic inflammatory disease characterized by plaque accumulation in arterial walls, is a major contributor to cardiovascular events such as heart attacks and strokes. Vitamin D has emerged as a multifunctional hormone with pleiotropic effects, extending beyond its traditional role in calcium and bone metabolism. Through its anti-inflammatory, immunomodulatory, and antioxidative properties, vitamin D may influence the development and progression of atherosclerosis. The association between vitamin D deficiency and atherosclerosis has been extensively studied. Observational studies consistently report an inverse relationship between vitamin D levels, atherosclerotic risk factors, and markers of subclinical atherosclerosis. Mechanistically, vitamin D exerts anti-inflammatory effects, modulates immune responses, improves endothelial function, and influences lipid metabolism, all of which play critical roles in atherosclerosis development and plaque stability. Furthermore, vitamin D deficiency has been linked to an increased risk of cardiovascular events. Vitamin D influences thrombosis, platelet aggregation, arterial stiffness, blood pressure regulation, and overall vascular health, collectively contributing to cardiovascular event risk. However, the clinical implications of vitamin D for managing atherosclerosis and reducing cardiovascular event risk are still being explored. Randomized controlled trials investigating the cardiovascular benefits of vitamin D supplementation have yielded mixed results, necessitating further research to determine optimal dosages, durations, and patient populations. The review also addresses public health recommendations and future directions. Examining current guidelines, identifying research gaps, and considering public health implications are crucial for translating scientific knowledge into effective interventions. Raising awareness, implementing population-level strategies, and integrating vitamin D assessment into routine clinical practice are key to improving cardiovascular outcomes.

In-home dementia caregiving is associated with greater psychological burden and poorer mental health than out-of-home caregiving: a cross-sectional study

INTRODUCTION

Caregivers who live with a person with dementia who receives care, compared with those who live elsewhere, are often considered to experience greater levels of psychological and affective burden. The evidence for this is, however, only limited to studies employing small sample sizes and that failed to examine caregivers' psychological wellbeing. We address these issues in a large cohort of dementia caregivers.

METHODS

We conducted a cross-sectional study comparing caregivers living with a dementia care recipient (n = 240) to caregivers living elsewhere (n = 255) on caregivers' burden, anxiety, and depression.

RESULTS

We found that caregivers living with the care recipient relative to those living elsewhere showed significantly greater burden and depression, but we found no group difference in anxiety.

CONCLUSIONS

Our study adds to the evidence by showing that cohabiting with a care recipient with dementia is associated with greater burden and poorer psychological wellbeing. Strategies aiming to improve caregivers' burden and psychological wellbeing should take account of caregivers' living arrangements.

PARE0018 WEBSITE FOR PARENTS OF CHILDREN WITH JUVENILE IDIOPATHIC ARTHRITIS REDUCES PARENTING STRESS

Background:

Having a child with JIA presents many challenges. Many parents experience considerable stress. Parental distress and functioning have been found to be related to child outcomes (Cousino, 2013), therefore interventions that help parents to manage their child’s illness are important for both parents and child. We developed a website for parents of children with newly diagnosed JIA to help increase parental confidence in managing their child’s arthritis and reduce parenting stress.

Objectives:

To evaluate the efficacy of a web-based tool ‘WebParC’ for parents of children with JIA.

Methods:

Design:Multi-centre randomised controlled trial conducted in 16 tertiary paediatric rheumatology centres in England.

Participants:Parent(s) of children aged ≤12 years, diagnosed with JIA within the previous six months.

Procedures:Parents were enrolled when they attended the rheumatology service and were randomised by household to either the intervention arm (I) who were given access to the website in addition to their child’s standard care or the control arm (C) who received standard care alone.

The primary outcome was parenting stress, measured with the Pediatric Inventory for Parents (PIP) (Streisand, 2001), which parents completed prior to randomisation and at 4-months and 12-months post randomisation.

Website content was developed by a multidisciplinary team including rheumatology, physiotherapy, ophthalmology, social work, podiatry, occupational therapy, clinical and health psychology along with parents of children with JIA. It includes information about JIA and its treatment plus a ‘toolkit’ for parents. The toolkit is based on cognitive-behavioural principles to develop skills for managing JIA-related issues.

Analysis:We conducted linear mixed models to examine the main effect of trial arm (I vs C), main effect of time (between 4M and 12M scores), and interaction between trial arm and time on PIP scores, after controlling for baseline scores.

Results:

A total of 220 parents (183 mothers, 37 fathers) of 203 children were randomised, 106 intervention and 114 controls. Parents mean (SD) age was 36.5 (6.5). Their children with JIA were mostly female (137/203, 67.5%), mean (SD) age of 6.1 (3.4) years. There were 107 (52.7%) with oligoarthritis, 65 (32%) polyarthritis, 8 (3.9%) systemic and 23 (11.3%) other JIA subtypes. Seventy (34.5%) were prescribed methotrexate.

Trial arms did not differ significantly at baseline except for parent education, which was higher in the intervention group and was controlled for in the analysis.

Follow-up assessments were completed by 133 (I60, C73) at 4M and 124 (I58, C66) at 12M.

We found significant main effects of trial arm on PIP Difficulty (p=0.022, Control (Mean=93.62, SE=2.717) > Intervention (Mean=84.23, SE=3.025)) and PIP Frequency (p= 0.008, Control (Mean=95.78, SE=2.400) > Intervention (Mean=86.23, SE=2.622), with Controls reporting significantly greater frequency and difficulty of stressful events than the Intervention group (Fig 1).

Conclusion:

This trial found that a website for parents of children with JIA can help to reduce parenting stress.

References:

[1]Cousino MK, Hazen RA. J Pediatr Psychol 2013; 38(8):809-28

[2]Streisand R, Braniecki S, Tercyak KP, Kazak AE. J Pediatr Psychol 2001; 26(3):155-62.

Acknowledgments:

We thank all parent participants, the health professionals and parents who developed website content and the clinical teams who supported recruitment.

Funded by NIHR RfPB.

Disclosure of Interests:

Kathleen Mulligan: None declared, Shashivadan Hirani: None declared, Sally Clarke: None declared, Neil Evans: None declared, Chris Flood: None declared, Jo Taylor: None declared, Lucy Wedderburn Speakers bureau: Pfizer, Stanton Newman Grant/research support from: Yes Baxter Healthcare Educational Grants not in relation to rheumatology, Speakers bureau: Yes Baxter Healthcare and Merke Sharp and Dome

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Current Products and Practices

Personal Digital Assistants (PDAs) have certain advantages over conventional diaries and are thought of as the 'electronic filofax'. They can be backed up, used for personal and professional organization, integrated with mobile phones for email and Internet access, image storage, logbook functions and audit. They are limited when used for desktop functions. This article attempts to highlight the current advantages and disadvantages of PDAs for use in orthodontics, and provides some guidance to those who are considering the purchase of such a device.

A late-forming mandibular supernumerary: a complication of space closure

This case report describes a situation in which a mandibular supernumerary developed during orthodontic treatment and prevented space closure.

Experimental autoimmune encephalomyelitis induced with a combination of myelin basic protein and myelin oligodendrocyte glycoprotein is ameliorated by administration of a single myelin basic protein peptide

Multiple sclerosis is an autoimmune disease of the central nervous system in which T cell reactivity to several myelin proteins, including myelin basic protein (MBP), proteolipid protein, and myelin oligodendrocyte glycoprotein (MOG), has been implicated in the perpetuation of the disease state. Experimental autoimmune encephalomyelitis (EAE) is used commonly as a model in which potential therapies for multiple sclerosis are evaluated. The ability of T cell epitope-containing peptides to down-regulate the disease course is well documented for both MBP- and proteolipid protein-induced EAE, and recently has been shown for MOG-induced EAE. In this study, we describe a novel EAE model, in which development of severe disease symptoms in (PL/J x SJL)F1 mice is dependent on reactivity to two different immunizing Ags, MBP and MOG. The disease is often fatal, with a relapsing/progressive course in survivors, and is more severe than would be predicted by immunization with either Ag alone. The MOG plus MBP disease can be treated postinduction with a combination of the MOG 41-60 peptide (identified as the major therapeutic MOG epitope for this strain) and the MBP Ac1-11[4Y] peptide. A significant treatment effect can also be obtained by administration of the MBP peptide alone, but this effect is strictly dose dependent. This MBP peptide does not treat the disease induced only with MOG. These results suggest that peptide immunotherapy can provide an effective means of mitigating disease in this model, even when the treatment is targeted to only one component epitope or one component protein Ag of a diverse autoimmune response.

Integrated clinical experience with tolerogenic peptides

More than 2,000 patients have been dosed in the clinical development programs for Allervax Cat and Ragweed products in North America, Europe and Japan. Two peptides derived from Fel d 1 and three peptides derived from Amb a 1 were selected for clinical development following T cell epitope mapping of these major allergens. Clinical activity has been demonstrated in several dose regimens containing 75 and 750 microg of each component peptide given in 4-6 doses over 2-4 weeks. Greater activity has been seen with higher doses. Immediate hypersensitivity to treatment peptides is rarely seen and can be avoided through patient screening. A putative pathway resulting in histamine-mediated but IgE-independent allergic symptoms, similar in nature and severity to natural allergen exposure, has been identified in association with treatment. These manifestations are more pronounced in cat than ragweed allergy and are consistent with the respective diseases. When desired, the symptoms may be ameliorated with administration of H1 blockers prior to symptom appearance. The seasonal rise in allergen-specific IgE is blunted in association with therapy. Antigen-specific antibody levels (IgE and IgG), T cell primary proliferation and immediate skin test sensitivity will be followed in longer-term studies.

IL-4 production by allergen-stimulated primary cultures: identification of basophils as the major IL-4-producing cell type

As a potent inducing agent for IgE production and differentiation factor for allergen-specific Th2 cells, IL-4 is a key regulatory cytokine both in the pathogenesis of allergic disease and in the ongoing allergic response. The assay of in vitro IL-4 production has often been used to compare the allergen responses of T cells isolated from atopic and non-atopic subjects. Because peripheral blood basophils also have the capacity to respond to specific allergen by producing IL-4, we investigated the relative contribution of these two cell types to IL-4 production in allergen-stimulated primary cultures. Among unfractionated peripheral blood mononuclear cells (PBMC), the major producers of detectable IL-4 in primary in vitro cultures were found to be basophils based on: (i) an allergen dose-response corresponding closely to that required for basophil histamine release and lower than that required for T cell activation; (ii) a rapid time course for IL-4 production (detectable at 3 h), inconsistent with the typical activation requirements of fresh T cells; (iii) the production of comparable levels of IL-4 in cultures stimulated with allergen or anti-IgE; and (iv) the complete loss of detectable IL-4 production following specific depletion of basophils from PBMC. The T cells in these cultures were functionally able to produce IL-4, as demonstrated by mitogen activation of basophil-depleted PBMC. These findings demonstrate that although IL-4 production in primary in vitro cultures can be used as a sensitive indicator of allergen responsiveness, the accurate interpretation of this result requires identification of the responding cell type. Furthermore, these findings raise the possibility that basophil production of IL-4 early in the course of allergen stimulation may shape subsequent T cell responses both in vivo and in vitro.

1H NMR studies on an Asn-linked glycopeptide. GlcNAc-1 C2-N2 bond is rigid in H2O

The conformation of an Asn-linked glycopeptide in H2O was studied by two-dimensional 1H NMR. Nonexchangeable proton and exchangeable amide (NH) proton resonances were assigned for the hen ovomucoid glycopeptide 1, Ser-Ile-Glu-Phe-Gly-Thr-Asn Ile-Ser-Lys, with pentasaccharide Man alpha 1-3 (Man alpha 1-6)Man beta 1-4GlcNAc beta 1-4GlcNAc beta 1-NH attached to the Asn7 gamma-carboxamide. The pentasaccharide increases the local correlation times of amino acid residues near the N-glycosylation site. Nuclear Overhauser effect (NOE) measurements on 1 and the corresponding Man3-GlcNAc2 pentasaccharide 3 show that the attached peptide does not perturb O-glycoside conformation. Sequential dNN (i, i + 1) NOEs in the Thr6-Ser9 region indicate populations of folded structure near the N-glycosylation site of both glycopeptide 1 and aglycosyl peptide 2. However, the Man3GlcNAc2 pentasaccharide does not dramatically affect the average conformation of either the peptide backbone or the Asn7 side chain. GlcNAc NH protons were studied at pH 3.0; and NOE and 3JNH data were used to constrain the glycopeptide's GlcNAc-1 side chain dihedral angle (tau) (C1-C2-N2-C7(Ac)). The glycopeptide's core GlcNAc-1 C2-N2 side chain bond is not flexible in H2O. A strong GlcNAc-1 NH2-H3 NOE, a medium strength NH2-H1 NOE, and a weak NH2-H2 interaction suggest that GlcNAc-1 has a rigid C2-N2 bond, with tau between 95 and 115 degrees. No evidence was found for intramolecular hydrogen bonds restricting this C2 side chain torsion. It may be that GlcNAc-1's rigid planar N-glycosidic linkage limits the conformational space available to the adjacent C2 acetamido side chain.

Substrate specificity of human liver neutral alpha-mannosidase

The digestion of radiolabelled natural oligosaccharide substrates by human liver neutral alpha-mannosidase has been studied by h.p.l.c. and h.p.t.l.c. The high-mannose oligosaccharides Man9GlcNAc and Man8GlcNAc are hydrolysed by the enzyme by two distinct non-random routes to a common product of composition Man6GlcNAc, which is then slowly converted into a unique Man5GlcNAc oligosaccharide, Man alpha(1----2)Man alpha(1----2)Man alpha(1----3)[Man alpha (1----6)] Man beta(1----4)GlcNAc. These pathways are different from the processing and lysosomal catabolic pathways for these structures. In particular, the alpha(1----2)-linked mannose residues attached to the core alpha(1----3)-linked mannose residue are resistant to hydrolysis. The key processing intermediate, Man alpha(1----3)[Man alpha(1----6)]Man alpha(1----6)[Man alpha(1----3)] Man beta(1----4)GlcNAc, is not produced in the digestion of high-mannose glycans by the neutral alpha-mannosidase, but it is hydrolysed by the enzyme by a non-random route to Man beta(1----4)GlcNAc via the core structure Man alpha(1----3)[Man alpha(1----6)]Man beta(1----4)GlcNAc. In contrast with its ready hydrolysis by lysosomal alpha-mannosidase, the core alpha(1----3)-mannosidic linkage is quite resistant to hydrolysis by neutral alpha-mannosidase. The precise specificity of neutral alpha-mannosidase towards high-mannose oligosaccharides suggests that it has a role in the modification of such structures in the cytosol.

Transgenic expression of a variant of human tissue-type plasminogen activator in goat milk: purification and characterization of the recombinant enzyme

A glycosylation variant of human tissue-type plasminogen activator (tPA) designated longer-acting tissue-type plasminogen activator (LAtPA) was extensively purified from the milk of a transgenic goat by a combination of acid fractionation, hydrophobic interaction chromatography and immunoaffinity chromatography. This scheme provided greater than 8,000-fold purification of the protein, a cumulative yield of 25% and purity greater than 98% as judged by SDS gel electrophoresis. SDS gel electrophoresis revealed that the transgenic enzyme was predominantly the "two chain" form of the protease. The specific activity of the purified transgenic protein, based on the average of the values obtained for three different preparations, was 610,000 U/mg as judged by amidolytic activity assay. This was approximately 84% of the value observed for the recombinant enzyme produced in mouse C127 cells. Analysis of the transgenic protein indicated that it had a significantly different carbohydrate composition from the recombinant enzyme produced in C127 cells. Molecular size analysis of the oligosaccharides from the transgenic and C127 cell-derived LAtPA preparations confirmed their differences and showed that the mouse cell-derived preparation contained larger, complex-type N-linked oligosaccharide structures than the material produced in goat mammary tissue.

Cloning and expression of peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F in Escherichia coli

The peptide-N4-(N-acetyl-beta-D-glucosaminyl) asparagine amidase F (PNGase F) gene from Flavobacterium meningosepticum was cloned into a high copy number Escherichia coli plasmid. Levels of PNGase F activity produced in cultures of the recombinant strain were up to 100-fold higher than those obtained in cultures of F. meningosepticum. The complete PNGase F gene sequence was determined. Comparison of the predicted amino acid sequence of pre-PNGase F to the N-terminal sequence of the native mature enzyme indicates that the protein is synthesized with a 40-amino acid signal sequence that is removed during secretion in F. meningosepticum. The recombinant PNGase F produced in E. coli is a mixture of products comprised predominantly of two proteins with molecular masses of 36.3 and 36.6 kDa. These proteins have a higher apparent molecular mass than the 34.7-kDa native enzyme. N-terminal amino acid sequencing demonstrated that these higher molecular mass products result from cleavage of the pre-PNGase F in E. coli upstream of the native N terminus. The PNGase F gene was engineered to encode a preenzyme that was processed in E. coli to give an N terminus identical to that of the native enzyme. Purified preparations of this form of recombinant PNGase F were shown to be suitable for glycoprotein analyses since they possess no detectable endo-beta-N-acetylglucosaminidase F, exoglycosidase, or protease activity.

Use of N-glycanase to release asparagine-linked oligosaccharides for structural analysis

An enzymatic procedure for releasing asparagine-linked oligosaccharides from glycoproteins by treatment with N-glycanase (peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase) has been investigated. Ribonuclease B, transferrin, fetuin, and alpha 1-acid glycoprotein were treated with N-glycanase and the released oligosaccharides were radiolabeled with NaB3H4. Lectin staining of the N-glycanase-treated proteins indicated that the deglycosylation reactions had proceeded to completion. The labeled carbohydrate chains were analyzed by HPLC on Micro-Pak AX-5 and AX-10 columns. The proportion of high-mannose and bi-, tri-, and tetraantennary complex chains obtained from each glycoprotein was in agreement with literature values. These results demonstrate that N-glycanase provides a simple method to release all common classes of asparagine-linked oligosaccharides from a glycoprotein in a form that can be radiolabeled directly for structural analysis.

A vesicular intermediate in the transport of hepatoma secretory proteins from the rough endoplasmic reticulum to the Golgi complex

We have identified a vesicle fraction that contains alpha 1-antitrypsin and other human HepG2 hepatoma secretory proteins en route from the rough endoplasmic reticulum (RER) to the cis face of the Golgi complex. [35S]Methionine pulse-labeled cells were chased for various periods of time, and then a postnuclear supernatant fraction was resolved on a shallow sucrose-D2O gradient. This intermediate fraction has a density lighter than RER or Golgi vesicles. Most alpha 1-antitrypsin in this fraction (P1) bears N-linked oligosaccharides of composition similar to that of alpha 1-antitrypsin within the RER; mainly Man8GlcNac2 with lesser amounts of Man7GlcNac2 and Man9GlcNac2; this suggests that the protein has not yet reacted with alpha-mannosidase-I on the cis face of the Golgi complex. This light vesicle species is the first post-ER fraction to be filled by labeled alpha 1-antitrypsin after a short chase, and newly made secretory proteins enter this compartment in proportion to their rate of exit from the RER and their rate of secretion from the cells: alpha 1-antitrypsin and albumin faster than preC3 and alpha 1-antichymotrypsin, faster, in turn, then transferrin. Deoxynojirimycin, a drug that blocks removal of glucose residues from alpha 1-antitrypsin in the RER and blocks its intracellular maturation, also blocks its appearance in this intermediate compartment. Upon further chase of the cells, we detect sequential maturation of alpha 1-antitrypsin to two other intracellular forms: first, P2, a form that has the same gel mobility as P1 but that bears an endoglycosidase H-resistant oligosaccharide and is found in a compartment--probably the medial Golgi complex--of density higher than that of the intermediate that contains P1; and second, the mature sialylated form of alpha 1-antitrypsin.

In vivo evaluation of hydroxypyridone iron chelators in a mouse model

The 59Fe excretion caused by a range of bidentate N-substituted [R group = methyl (CP20), ethyl (CP21), propyl (CP22), isopropyl (CP23), butyl (CP24) or hexyl (CP25)] 3-hydroxypyrid-4-one chelators in iron-overloaded mice is presented. All the compounds cause significant iron excretion when given intraperitoneally, but that the most hydrophobic compounds, CP24 and CP25, were toxic except at low doses. The excretion caused by CP21, CP22 and CP23 were significantly greater than that caused by CP20 and slightly larger than that caused by an equivalent dose of desferrioxamine. These compounds (CP20 through CP24) also caused significant excretion of 59Fe when administered orally. Compounds CP21, CP22 and CP24 were significantly more active than compounds CP20 and CP23. It is concluded that the N-ethyl or N-propyl 3-hydroxypyrid-4-ones are the most promising compounds for clinical application. Preliminary experiments using a hexadentate pyrid-2-one, CP130, show that this causes significant 59Fe excretion both when given intraperitoneally or orally.

Structural analysis of the asparagine-linked oligosaccharides of human complement component C3

The asparagine-linked oligosaccharides of human C3 were characterized. The C3 oligosaccharides were released by endo-beta-N-acetylglucosaminidase H and were analysed by lectin affinity chromatography and h.p.l.c. The released oligosaccharides bound tightly to concanavalin A-Sepharose and were not retained by agarose-bound wheat-germ agglutinin, indicating that they were only of high-mannose type. Two major oligosaccharide structures were separated from both the alpha- and beta-chains of C3 by h.p.l.c. on Micropak AX-5, calibrated with high-mannose-type oligosaccharides of known structures. The oligosaccharide structures on the alpha-chain have the compositions (Man)9(GlcNAc)2-Asn and (Man)8 (GlcNAc)2-Asn, and those on the beta-chain have the compositions (Man)6(GlcNAc)2-Asn and (Man)5(GlcNAc)2-Asn.

Changes in human plasma alpha-D-mannosidase activity during pregnancy

There are significant and progressive increases in plasma acidic (pH optimum 4.2) and intermediate (pH optimum 5.6) alpha-mannosidase during pregnancy. The acidic alpha-mannosidase in plasma from pregnant women binds to concanavalin A and has the same apparent molecular weight as the acidic alpha-mannosidase in control plasma. The 2-3-fold increase in acidic alpha-mannosidase in pregnancy is due to an increase in the most negatively charged form of acidic alpha-mannosidase, B2, which is slightly more negatively charged than its counterpart in the control plasma. The intermediate alpha-mannosidase, which increases by approximately 50% during pregnancy, can be resolved by a combination of chromatography on concanavalin A and gel filtration into the same forms found in control plasma.

Leukocyte complement: interleukin-like properties of factor Bb

It has been previously shown that the activated form of Factor B (Factor Bb) of the alternative pathway of complement activation stimulates monocyte spreading and killing of xenogenic erythrocytes and staphylococci. Factor Bb also stimulates lymphocyte blastogenesis in vitro, and native (uncleaved) Factor B is a major constitutive product of murine macrophages. To evaluate the possible "monokine" or "lymphokine"-like properties of Factor Bb, a radioimmunoassay was developed to measure the quantities of Factor B in phytohemagglutinin (PHA)-mitogen-stimulated cultures of human peripheral blood mononuclear cells. Nonstimulated mononuclear cell cultures from human peripheral blood (containing 10-14% monocytes and greater than 85% lymphocytes) at a density of 3 X 10(6) cells/ml (in serum-free medium) released less than 7 X 10(-10) M/liter (60 ng/ml) of Factor B antigen in 24 hr at 37 degrees C, and when mononuclear cells were stimulated with PHA mitogen in serum-free medium, the levels of Factor B antigen in media at 24 hr were significantly higher 1-3 X 10(-8) M/liter (0.9-2.8 micrograms/ml). The molecular size of Factor B in these media was 50-65 kDa by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a size appropriate for Factor Bb (60 kDa). Since pathological effects of macrophages in autoimmune disease may result from the release of lysosomal hydrolases, the effects of purified Factor Bb on mononuclear phagocytes were investigated in an in vitro system of murine peritoneal exudate macrophages. Factor Bb induced secretion of marker lysosomal hydrolases N-acetyl-beta-D-glucosaminidase (hexosaminidase) and beta-glucuronidase from thioglycollate-elicited murine peritoneal exudate macrophages in a dose-response and kinetic manner. Hydrolase release was induced in serum-free medium without a known particulate activator at a concentration of 80-200 nM (5-13 micrograms/ml) Factor Bb. Maximal release occurred in 3-5 hr at 37 degrees C and extracellular enzyme activity of hexosaminidase and glucuronidase increased as intracellular enzyme levels decreased, suggesting that Factor Bb triggers release of these enzymes from intracellular lysosomal pools. These results provide an example of a complement protein which is synthesized, released, and activated during mononuclear cell culture and which induces release of lysosomal enzymes from macrophages. In conventional terminology, Factor B or Factor Bb might be termed a "lymphokine," "monokine," or "interleukin".

Complement activation in type 1 human diabetes

Complement activation was quantitated in serum and plasma of diabetic and normal subjects by sensitive competitive equilibrium radioimmunoassays (RIA) for C3a, C4a, C5a, Factor B, and a newly described C5 neoantigen (termed C5 activation antigen, and abbreviated C5-AA) in a stable 54-kDa fragment of C5. Plasma C3a levels were significantly elevated in 8 of 16 patients with newly diagnosed Type 1 diabetes (P less than 0.0005) with the mean C3a concentration for these patients being more than 10-times greater than the mean value of normal controls. C4a levels were also elevated in 2 of these patients (P less than 0.02), but C5a levels, although higher than normal, were not significantly increased. In contrast, the levels of C5-AA in the serum of all patients (11/11) with chronic Type 1 diabetes were significantly higher than in control Type 2 patients (noninsulin-dependent diabetes) (P less than 0.0005) and 4 of 7 patients with new onset insulin-dependent diabetes mellitus also had significantly higher levels of C5-AA than the Type 2 patients (P less than 0.01). The levels of Factor B in the serum of 5 of 9 patients with new onset diabetes were significantly higher than normal (P less than 0.0025). Five recent onset Type 1 diabetes patients were evaluated longitudinally for C3a, C4a, and C5a: in 3 the levels of C3a were elevated during new onset disease decreasing into the normal range during remission; in 2 of these patients C4a was also significantly elevated and the levels decreased during remission; and in 3 patients the levels of C5a were not significantly elevated but they decreased during remission. Purified human complement proteins and complement hemolytic assays were used to measure complement activation in serum during incubation with rat pancreatic islet cells. With diluted normal human serum, less than 20% of C3 or Factor B were consumed during 30 min at 37 degrees C, while with new onset Type 1 diabetic patient sera up to 90% of C3 and Factor B were consumed in 5/6 sera and 4/6 sera, respectively. These findings suggest (a) that complement activation fragments C3a, C4a, and C5a are generated in vivo in new onset Type 1 diabetes; (b) that both the classical and the alternative complement pathways may be activated; and (c) that this may result in a measurable activation of C5 generating biologically and immunologically active C5a and other C5 activation fragments.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization of the conglutinin binding site on the third component of human complement

The binding site on the human third complement component for bovine conglutinin has been located. C3 fragments were purified to homogeneity by preparative SDS-polyacrylamide-gel electrophoresis. Only the N-terminal 27,000 dalton (Da) fragment of the alpha'-chain and the beta-chain were found to be glycosylated, and the carbohydrate was susceptible to endo-beta-N-acetylglucosaminidase H. This finding indicates that only high mannose or hybrid-type oligosaccharide chains are present on the C3 molecule. Binding to conglutinin was determined by an enzyme-linked immunosorbent assay and occurred with C3b, iC3b, C3c, the alpha-chain, and the 27,000 Da fragment of the alpha'-chain, but not with C3d or the C-terminal 40,000 Da fragment of the alpha'-chain. The beta-chain displayed very weak interaction. Binding to conglutinin could be inhibited by EDTA, N-acetylglucosamine, and to a lesser degree by mannose. Enzymatic removal of the carbohydrate from the C3 molecule abolished binding to conglutinin. It is concluded that bovine conglutinin binds to the carbohydrate moiety located on the N-terminal 27,000 Da polypeptide of the alpha-chain.

Localization of the conglutinin binding site on the third component of human complement

The binding site on the human third complement component for bovine conglutinin has been located. C3 fragments were purified to homogeneity by preparative SDS-polyacrylamide-gel electrophoresis. Only the N-terminal 27,000 dalton (Da) fragment of the alpha'-chain and the beta-chain were found to be glycosylated, and the carbohydrate was susceptible to endo-beta-N-acetylglucosaminidase H. This finding indicates that only high mannose or hybrid-type oligosaccharide chains are present on the C3 molecule. Binding to conglutinin was determined by an enzyme-linked immunosorbent assay and occurred with C3b, iC3b, C3c, the alpha-chain, and the 27,000 Da fragment of the alpha'-chain, but not with C3d or the C-terminal 40,000 Da fragment of the alpha'-chain. The beta-chain displayed very weak interaction. Binding to conglutinin could be inhibited by EDTA, N-acetylglucosamine, and to a lesser degree by mannose. Enzymatic removal of the carbohydrate from the C3 molecule abolished binding to conglutinin. It is concluded that bovine conglutinin binds to the carbohydrate moiety located on the N-terminal 27,000 Da polypeptide of the alpha-chain.

Mucolipidosis III beta-N-acetyl-D-hexosaminidase A. Purification and properties

Mucolipidosis III acid hydrolases possess an altered carbohydrate recognition marker needed for their lysosomal localization. As a result of this alteration, a portion of these enzymes is secreted from the cell to the extracellular spaces. The structural changes that may have occurred to one of these secreted enzymes, beta-N-acetyl-d-hexosaminidase A (EC 3.2.1.52) were investigated. Normal and mucolipidosis III urinary beta-N-acetyl-d-hexosaminidase A were purified to apparent homogeneity by using affinity [Sepharose-2-acetamido-N-(epsilon-aminocaproyl)-2-deoxy-beta- d-glucopyranosylamine] and ion-exchange (DEAE- and CM-cellulose) chromatography. Sodium dodecyl sulphate/polyacrylamide-slab-gel electrophoresis showed that both enzymes had similar subunit patterns consisting of apparent mol.wts. of 68000, 60000-58000, 55000 and 29000. Differences, however, were noted in the relative proportions of the protein bands where the normal urinary beta-N-acetyl-d-hexosaminidase A contained predominantly the smaller subunits, whereas the mucolipidosis III enzyme had a predominance of the larger subunits. The binding of mucolipidosis III beta-N-acetyl-d-hexosaminidase A to Ricinus communis lectin and concanavalin A with and without endo-beta-N-acetyl-d-glucosaminidase H treatment indicated that the mutation leads to a modification of a portion of the normally occurring high-mannose-type oligosaccharide units to the complex-type. This was further supported by carbohydrate compositional analysis, which revealed a mannose/galactose ratio of 2.1 for the mucolipidosis III beta-N-acetyl-d-hexosaminidase A compared with a ratio of 3.5 for the normal enzyme. Our results indicate that as a result of their inability to be properly localized to the lysosome the majority of the mucolipidosis III lysosomal hydrolase high-mannose oligosaccharide units are further processed to the complex-type before secretion of predominantly higher-molecular-weight subunits from the cell.

A study of highly purified mucolipidosis III urinary N-acetyl-beta-D-hexosaminidase B

Highly purified N-acetyl-beta-D-hexosaminidase B from normal urine and urine of a patient with mucolipidosis III was used to determine whether it has undergone any of the alterations associated with this genetic defect. Examination by sodium dodecyl sulphate/polyacrylamide gel electrophoresis showed that both the enzyme preparations contained protein components with apparent Mr values of 55 000 and 28 000. No differences in the binding and apparent KI (50%) to concanavalin A of the normal and mucolipidosis III enzymes were detected. However, the patient's N-acetyl-beta-D-hexosaminidase B had a slightly greater affinity for the lectin from Ricinus communis than did the normal enzyme. Two-dimensional tryptic peptide maps of the corresponding normal and the patient's N-acetyl-beta-D-hexosaminidase B subunits showed considerable homology. These results indicate that N-acetyl-beta-D-hexosaminidase b does not undergo the significant carbohydrate alterations characteristic of other acid hydrolases in mucolipidosis III.

Biochemical studies on a case of feline mannosidosis

Evidence is presented for the biochemical diagnosis of the first case of feline mannosidosis. A marked deficiency of acidic alpha-D-mannosidase in the brain, kidney and liver and excessive excretion of mannose-rich oligosaccharides in the urine were found in a kitten suffering from a nervous disorder. Residual acidic alpha-D-mannosidase, ranging from 2 to 5.5% of the normal activity, was observed in the tissues of the affected kitten. It has similar kinetic and physicochemical properties to the normal activity. The amount of mannose in the urine of the affected kitten was 19-fold greater than in a comparable control, and the molar ratio of mannose to N-acetylglucosamine was approx. 6 : 1. High concentrations of neutral oligosaccharides were detected in the urine. The predominant oligosaccharide appeared to be a hexasaccharide. The biochemical features of bovine, feline and human mannosidosis are compared, and it is concluded that feline mannosidosis may be a useful animal model for studying the human disease.

Plasma alpha-D-mannosidase in mucolipidosis II and mucolipidosis III

There is a marked increase in the acidic alpha-D-mannosidase in the plasma of a patient with mucolipidosis II and of a patient with mucolipidosis III. A small proportion (3--4%) of this acidic alpha-D-mannosidase does not bind to concanavalin A-Sepharose, suggesting an alteration in the glycosylation and some of the enzyme in these disorders. A slight elevation in intermediate alpha-D-mannosidase was also demonstrated in these samples by using a differential assay for the acidic and intermediate alpha-D-mannosidase activities. A combination of chromatography on concanavalin A-Sepharose and Sephadex G-200 showed that intermediate alpha-D-mannosidase components I2 and I4, which account for approximately 80% of the intermediate activity in normal plasma, were also present in ML II and ML III plasma. The minor intermediate alpha-D-mannosidase components in normal plasma, I1 and I3 were either present in small amounts or not detected. These results suggest that a defect in intermediate alpha-D-mannosidase is unlikely to be the primary defect in these disorders.

The multiple forms of alpha-D-mannosidase in human plasma

The acidic alpha-D-mannosidase in human plasma closely resembles liver acidic alpha-D-mannosidase in its affinity for concanavalin A-Sepharose, molecular weight and resolution into multiple components on DEAE-cellulose. A combination of chromatography on concanavalin A-Sepharose and gel filtration on Sephadex G-200 and Sepharose 6B suggests that four forms of intermediate alpha-D-mannosidase, which differ either in their molecular weight of affinity for concanavalin A, exist in human plasma. A practical classification and nomenclature for the multiple forms of intermediate alpha-D-mannosidase in plasma based on molecular weight and affinity for concanavalin A is proposed. Multiple forms of intermediate alpha-D-mannosidase were also observed by ion-exchange chromatography on DEAE-cellulose, but there was not a simple correlation between these forms and those obtained with the other separation procedures. The form of intermediate alpha-D-mannosidase least abundant in plasma, approx. 7% of the activity, has very similar properties to the neutral alpha-D-mannosidase in human liver. In contrast, the other three forms of intermediate alpha-D-mannosidase, which account for over 90% of the activity, do not appear to be present in liver, except perhaps in trace amounts.

Measurement of the alpha-mannosidase activities in human plasma by a differential assay

A differential assay based on their difference in thermal stability has been used to measure the acidic and true intermediate alpha-mannosidases in the plasma of cntrols and individuals homozygous or heterozygous for mannosidosis. The intermediate activity was found to be independent of age, sex or mannosidosis genotype. The acidic alpha-mannosidase did not vary significantly with age or between sexes for groups of the same age. The concentrations of acidic and intermediate alpha-mannosidase showed a positive correlation for adults but not for children. The ratio of acidic to true intermediate alpha-mannosidase might therefore be a useful secondary test for the detection of adult heterozygotes for mannosidosis.