Jens V. Andersen

Biologic treatment or immunomodulation is not associated with postoperative anastomotic complications in abdominal surgery for Crohn's disease

Abstract Objectives. There are concerns that biologic treatments or immunomodulation may negatively influence anastomotic healing. This study investigates the relationship between these treatments and anastomotic complications after surgery for Crohns disease. Patients and methods. Retrospective study on 417 operations for Crohns disease performed at four Danish hospitals in 2000–2007. Thirty-two patients were preoperatively treated with biologics and 166 were on immunomodulation. In total, 154 were treated with corticosteroids of which 66 had prednisolone 20 mg or more. Results. Anastomotic complications occurred at 13% of the operations. There were no difference in patients on biologic treatment (9% vs. 12% (p = 0.581)) or in patients on immunomodulation (10% vs. 14% (p = 0.263)). Patients on 20 mg prednisolone or more had more anastomotic complications (20% vs. 11% (p = 0.04)). Anastomotic complications were more frequent after a colo-colic anastomosis than after an entero-enteric or entero-colic (33% vs. 12% (p = 0.013)). Patients with anastomotic complications were older (40 years vs. 35 years (p = 0.014)), had longer disease duration (7.5 years vs. 4 years (p = 0.04)), longer operation time (155 min vs. 115 min (p = 0.018)) and more operative bleeding (200 ml vs. 130 ml (p = 0.029)). Multivariate analysis revealed preoperative treatment with prednisolone 20 mg or more, operation time and a colo-colic anastomosis as negative predictors of anastomotic complications. Conclusions. Preoperative biologic treatment or immunomodulation had no influence on anastomotic complications. The study confirms previous findings of corticosteroids and a colo-colic anastomosis as negative predictors and also that surgical complexity, as expressed by bleeding and operation time, may contribute to anastomotic complications.

Implications of muscular defense in testing for the anterior drawer sign in the knee: A stress radiographic investigation

This study was performed with the aim of shedding some light on the effect of muscular guarding during clinical testing of the knee for anteroposterior laxity. Twenty physicians were tested on a knee phantom, for force used during testing for the anterior drawer sign. The force used averaged 109 N (range, 70 to 180 N). Fifteen patients were examined by stress radiogra phy. Radiographs were taken with the knee flexed to 90° (the drawer test position) and with the knee flexed to 15° (the Lachman position). A comparison was made between the laxity measured on forward traction in the relaxed knee, and during traction while the patient was instructed to counteract the forward displacement of the tibia by tensing the hamstrings, thus simulating muscular defense. The test procedure was executed first with 80 N and then with 160 N applied. The opposing effect of tensing the hamstrings on the anterior shift of the tibia was significantly less at 15° of knee flexion (with 80 N, P < 0.02; with 160 N, P < 0.05) than at 90°. With the hamstrings tensed and the knee flexed to 90°, no statistically significant gain in drawer sign was achieved by increasing the force from 80 to 160 N. With the knee in the Lachman position, increasing the force produced a significantly greater anterior drawer sign (P < 0.01).

Serum immunoglobulin G subclasses in patients with ulcerative colitis and Crohn's disease of different disease activities.

BACKGROUND Different concentrations of immunoglobulin G (IgG) subclass-producing cells in the mucosa of patients with ulcerative colitis and Crohns disease have previously been described. METHODS To evaluate serum concentration of IgG subclasses as a tool for diagnosis and disease activity in chronic inflammatory bowel disease, we compared serum concentrations of IgG, IgA, IgM, and immunoglobulin subclasses IgG1, IgG2, IgG3, and IgG4 by means of the radial immunodiffusion technique in 66 patients with ulcerative colitis and in 68 patients with Crohns disease of different clinical stages. Erythrocyte sedimentation rate, haemoglobin, and serum concentrations of albumin and orosomucoid were also determined. RESULTS The serum IgG1 concentration in patients with ulcerative colitis was 8.0 g/l significantly higher than in patients with Crohns disease (6.8 g/l) (p < 0.005), whereas the serum IgG2 concentration in patients with Crohns disease was 3.8 g/l, significantly increased compared with patients with ulcerative colitis (3.1 g/l) (p < 0.004). In patients with active ulcerative colitis the serum IgA level (2.03 g/l) was significantly lower than that in the patients with less active disease (2.74 g/l) (p < 0.03). No significant differences in serum concentrations of total IgG, IgG3, IgG4, and IgM were found between groups of patients with ulcerative colitis and Crohns disease. The differences observed in IgG1, IgG2, and IgA concentrations, however, are small. CONCLUSIONS The serum concentrations of IgG, IgA, IgM, and IgG subclasses are of little value in the diagnostic procedures in individual patients and are not superior to conventional laboratory tests such as sedimentation rate and serum concentrations of orosomucoid and albumin.

Alterations in Cerebral Cortical Glucose and Glutamine Metabolism Precedes Amyloid Plaques in the APPswe/PSEN1dE9 Mouse Model of Alzheimer’s Disease

Alterations in brain energy metabolism have been suggested to be of fundamental importance for the development of Alzheimer’s disease (AD). However, specific changes in brain energetics in the early stages of AD are poorly known. The aim of this study was to investigate cerebral energy metabolism in the APPswe/PSEN1dE9 mouse prior to amyloid plaque formation. Acutely isolated cerebral cortical and hippocampal slices of 3-month-old APPswe/PSEN1dE9 and wild-type control mice were incubated in media containing [U-13C]glucose, [1,2-13C]acetate or [U-13C]glutamine, and tissue extracts were analyzed by mass spectrometry. The ATP synthesis rate of isolated whole-brain mitochondria was assessed by an on-line luciferin-luciferase assay. Significantly increased 13C labeling of intracellular lactate and alanine and decreased tricarboxylic acid (TCA) cycle activity were observed from cerebral cortical slices of APPswe/PSEN1dE9 mice incubated in media containing [U-13C]glucose. No changes in glial [1,2-13C]acetate metabolism were observed. Cerebral cortical slices from APPswe/PSEN1dE9 mice exhibited a reduced capacity for uptake and oxidative metabolism of glutamine. Furthermore, the ATP synthesis rate tended to be decreased in isolated whole-brain mitochondria of APPswe/PSEN1dE9 mice. Thus, several cerebral metabolic changes are evident in the APPswe/PSEN1dE9 mouse prior to amyloid plaque deposition, including altered glucose metabolism, hampered glutamine processing and mitochondrial dysfunctions.

Improved cerebral energetics and ketone body metabolism in db/db mice.

It is becoming evident that type 2 diabetes mellitus is affecting brain energy metabolism. The importance of alternative substrates for the brain in type 2 diabetes mellitus is poorly understood. The aim of this study was to investigate whether ketone bodies are relevant candidates to compensate for cerebral glucose hypometabolism and unravel the functionality of cerebral mitochondria in type 2 diabetes mellitus. Acutely isolated cerebral cortical and hippocampal slices of db/db mice were incubated in media containing [U-13C]glucose, [1,2-13C]acetate or [U-13C]β-hydroxybutyrate and tissue extracts were analysed by mass spectrometry. Oxygen consumption and ATP synthesis of brain mitochondria of db/db mice were assessed by Seahorse XFe96 and luciferin-luciferase assay, respectively. Glucose hypometabolism was observed for both cerebral cortical and hippocampal slices of db/db mice. Significant increased metabolism of [1,2-13C]acetate and [U-13C]β-hydroxybutyrate was observed for hippocampal slices of db/db mice. Furthermore, brain mitochondria of db/db mice exhibited elevated oxygen consumption and ATP synthesis rate. This study provides evidence of several changes in brain energy metabolism in type 2 diabetes mellitus. The increased hippocampal ketone body utilization and improved mitochondrial function in db/db mice, may act as adaptive mechanisms in order to maintain cerebral energetics during hampered glucose metabolism.

Glutamate dehydrogenase is essential to sustain neuronal oxidative energy metabolism during stimulation

The enzyme glutamate dehydrogenase (GDH; Glud1) catalyzes the (reversible) oxidative deamination of glutamate to α-ketoglutarate accompanied by a reduction of NAD+ to NADH. GDH connects amino acid, carbohydrate, neurotransmitter and oxidative energy metabolism. Glutamine is a neurotransmitter precursor used by neurons to sustain the pool of glutamate, but glutamine is also vividly oxidized for support of energy metabolism. This study investigates the role of GDH in neuronal metabolism by employing the Cns-Glud1−/− mouse, lacking GDH in the brain (GDH KO) and metabolic mapping using 13C-labelled glutamine and glucose. We observed a severely reduced oxidative glutamine metabolism during glucose deprivation in synaptosomes and cultured neurons not expressing GDH. In contrast, in the presence of glucose, glutamine metabolism was not affected by the lack of GDH expression. Respiration fuelled by glutamate was significantly lower in brain mitochondria from GDH KO mice and synaptosomes were not able to increase their respiration upon an elevated energy demand. The role of GDH for metabolism of glutamine and the respiratory capacity underscore the importance of GDH for neurons particularly during an elevated energy demand, and it may reflect the large allosteric activation of GDH by ADP.

Specificity of exogenous acetate and glutamate as astrocyte substrates examined in acute brain slices from female mice using methionine sulfoximine (MSO) to inhibit glutamine synthesis

Removal of endogenously released glutamate is mediated primarily by astrocytes and exogenous 13C‐labeled glutamate has been applied to study glutamate metabolism in astrocytes. Likewise, studies have clearly established the relevance of 13C‐labeled acetate as an astrocyte specific metabolic substrate. Recent studies have, however, challenged the arguments used to anchor this astrocyte specificity of acetate and glutamate. The aim of the current study was to evaluate the specificity of acetate and glutamate as astrocyte substrates in brain slices. Acutely isolated hippocampal and cerebral cortical slices from female NMRI mice were incubated in media containing [1,2‐13C]acetate or [U‐13C]glutamate, with or without methionine sulfoximine (MSO) to inhibit glutamine synthetase (GS). Tissue extracts were analyzed by gas chromatography‐mass spectrometry. Blocking GS abolished the majority of glutamine 13C‐labeling from [1,2‐13C]acetate as intended. However, 13C‐labeling of GABA was only 40‐50% reduced by MSO, suggesting considerable neuronal uptake of acetate. Moreover, labeling of glutamate from [1,2‐13C]acetate in the presence of MSO exceeded the level probable from exclusive labeling of the astrocytic pool, which likewise suggests neuronal acetate metabolism. Approximately 50% of glutamate was uniformly labeled in slices incubated with [U‐13C]glutamate in the presence of MSO, suggesting that neurons exhibit substantial uptake of exogenously provided glutamate.

Integrative Characterization of the R6/2 Mouse Model of Huntington’s Disease Reveals Dysfunctional Astrocyte Metabolism

Huntingtons disease is a fatal neurodegenerative disease, where dysfunction and loss of striatal and cortical neurons are central to the pathogenesis of the disease. Here, we integrated quantitative studies to investigate the underlying mechanisms behind HD pathology in a systems-wide manner. To this end, we used state-of-the-art mass spectrometry to establish a spatial brain proteome from late-stage R6/2 mice and compared this with wild-type littermates. We observed altered expression of proteins in pathways related to energy metabolism, synapse function, and neurotransmitter homeostasis. To support these findings, metabolic 13C labeling studies confirmed a compromised astrocytic metabolism and regulation of glutamate-GABA-glutamine cycling, resulting in impaired release of glutamine and GABA synthesis. In recent years, increasing attention has been focused on the role of astrocytes in HD, and our data support that therapeutic strategies to improve astrocytic glutamine homeostasis may help ameliorate symptoms in HD.

Impaired Hippocampal Glutamate and Glutamine Metabolism in the db/db Mouse Model of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a risk factor for the development of Alzheimers disease, and changes in brain energy metabolism have been suggested as a causative mechanism. The aim of this study was to investigate the cerebral metabolism of the important amino acids glutamate and glutamine in the db/db mouse model of T2DM. Glutamate and glutamine are both substrates for mitochondrial oxidation, and oxygen consumption was assessed in isolated brain mitochondria by Seahorse XFe96 analysis. In addition, acutely isolated cerebral cortical and hippocampal slices were incubated with [U-13C]glutamate and [U-13C]glutamine, and tissue extracts were analyzed by gas chromatography-mass spectrometry. The oxygen consumption rate using glutamate and glutamine as substrates was not different in isolated cerebral mitochondria of db/db mice compared to controls. Hippocampal slices of db/db mice exhibited significantly reduced 13C labeling in glutamate, glutamine, GABA, citrate, and aspartate from metabolism of [U-13C]glutamate. Additionally, reduced 13C labeling were observed in GABA, citrate, and aspartate from [U-13C]glutamine metabolism in hippocampal slices of db/db mice when compared to controls. None of these changes were observed in cerebral cortical slices. The results suggest specific hippocampal impairments in glutamate and glutamine metabolism, without affecting mitochondrial oxidation of these substrates, in the db/db mouse.

Total condylar knee arthroplasty. Implications of postoperative stability, evaluated by stress radiography

Knee sability and knee score were studied in 44 consecutive total knee replacements with the Insall/Burnstein Total Condylar Knee prosthesis. Knee stability was assessed by stress radiography. Statistical correlation was found between increasing antero-posterior laxity and increasing score on the New York Hospital for Special Surgery scoring scale, and between increasing antero-posterior laxity and increasing knee flexion ability. Tightness (total antero-posterior laxity <5mm) was associated with complaints of pain and compromised joint function.