Change in carbohydrate intake one year after Roux-en-Y gastric bypass: A prospective study.

Background and objectives: To investigate the effect of carbohydrate intake before laparoscopic Roux-en-Y gastric bypass (LRYGB) on body weight, body composition and glycaemic status after surgery. Methods: In a tertiary centre cohort study, dietary habits, body composition and glycaemic status were evaluated before and 3, 6 and 12 months after LRYGB. Detailed dietary food records were processed by specialized dietitians on the basis of a standard protocol. The study population was subdivided according to relative carbohydrate intake before surgery. Results: Before surgery, 30 patients had a moderate relative carbohydrate intake (26%-45%, M-CHO), a mean body mass index (BMI) of 40.4 ± 3.9 kg/m² and a mean glycated haemoglobin A1c (A1C) of 6.5 ± 1.2% compared to 20 patients with a high relative carbohydrate intake (> 45%, H-CHO), mean BMI of 40.9 ± 3.7 kg/m² (non-significant, NS) and a mean A1C of 6.2% (NS). One year after surgery, body weight, body composition and glycaemic status were similar in the M-CHO (n = 25) and H-CHO groups (n = 16), despite less caloric intake in the H-CHO group (1317 ± 285 g vs. 1646 ± 345 g in M-CHO, p < 0.01). Their relative carbohydrate intake converged to 46% in both groups, but the H-CHO group reduced the absolute total carbohydrate consumption more than the M-CHO group (190 ± 50 g in M-CHO vs. 153 ± 39 g in H-CHO, p < 0.05), and this was especially pronounced for the mono- and disaccharides (86 ± 30 g in M-CHO vs. 65 ± 27 g in H-CHO, p < 0.05). Conclusion: A high relative carbohydrate intake before LRYGB, did not influence the change in body composition or diabetes status after surgery, despite a significantly lower total energy intake and less mono- and disaccharide consumption after surgery.

Offering Guidance and Learning to Prescribers to Initiate Parenteral Nutrition using a Validated Electronic Decision TREE (OLIVE TREE).

Parenteral nutrition (PN) is recommended in patients nutritionally at risk and unable to receive oral or enteral nutrition. A standardized electronic PN order format could enhance appropriate PN prescribing. We developed the OLIVE TREE (Offering guidance and Learning to prescribers to Initiate PN using a Validated Electronic decision TREE), embedded in our electronic health record. We aimed to evaluate its validity and impact on physicians' prescribing behavior. A non-randomized before-after study was carried out in a tertiary care center. The OLIVE TREE comprises 120 individual items. A process validation was performed to determine interrater agreement between a pharmacist and the treating physician. To estimate the proportion of patients for whom the OLIVE TREE had an effective and potential impact on physicians' prescribing behavior, a proof of concept study was conducted. The proportion of patients for whom PN was averted and the proportion of decisions not in line with the recommendation were also calculated. The process validation in 20 patients resulted in an interrater agreement of 95.0%. The proof of concept in 73 patients resulted in an effective and potential impact on prescribing behavior in 50.7% and 79.5% of these patients, respectively. Initiation of PN was not averted and recommendations of the OLIVE TREE were overruled in 42.5% of the patients. Our newly developed OLIVE TREE has a good process validity. A substantial impact on prescribing behavior was observed, although initiation of PN was not avoided. In the next phase, the decision tree will be implemented hospital-wide.

Liraglutide for Weight Management in the Real World: Significant Weight Loss Even if the Maximal Daily Dose Is Not Achieved.

INTRODUCTION: Obesity is a global health challenge, and pharmacologic options are emerging. Once daily subcutaneous administration of 3 mg liraglutide, a glucagon like peptide-1 analogue, has been shown to induce weight loss in clinical trials, but real-world effectiveness data are scarce. METHODS: It is a single-centre retrospective cohort study of patients who were prescribed liraglutide on top of lifestyle adaptations after multidisciplinary evaluation. In Belgium, liraglutide is only indicated for weight management if the BMI is >30 kg/m2 or ≥27 kg/m2 with comorbidities such as dysglycaemia, dyslipidaemia, hypertension, or obstructive sleep apnoea. No indication is covered by the compulsory health care insurance. Liraglutide was started at 0.6 mg/day and uptitrated weekly until 3 mg/day or the maximum tolerated dose. Treatment status and body weight were evaluated at the 4-month routine visit. RESULTS: Between June 2016 and January 2020, liraglutide was prescribed to 115 patients (77% female), with a median age of 47 (IQR 37.7-54.0) years, a median body weight of 98.4 (IQR 90.0-112.2) kg, a BMI of 34.8 (IQR 32.2-37.4) kg/m2, and an HbA1c level of 5.6%. Five (4%) patients did not actually initiate treatment, 9 (8%) stopped treatment, and 8 (7%) were lost to follow-up. At the 4-month visit, the median body weight had decreased significantly by 9.2% to 90.8 (IQR 82.0-103.5) kg (p < 0.001). Patients using 3.0 mg/day (n = 60) had lost 8.0 (IQR 5.8-10.4) kg. The weight loss was similar (p = 0.9622) in patients that used a lower daily dose because of intolerance: 7.4 (IQR 6.2-9.6) kg for 1.2 mg (n = 3), 7.8 (IQR 4.1-7.8) kg for 1.8 mg (n = 16), and 9.0 (IQR 4.8-10.7) kg for 2.4 mg/day (n = 14). Weight loss was minimal if liraglutide treatment was not started or stopped prematurely (median 3.0 [IQR 0.3-4.8] kg, p < 0.001, vs. on treatment). Further analysis showed an additional weight reduction of 1.8 kg in the patients that had started metformin <3 months before the start of liraglutide (p < 0.001). The main reasons for liraglutide discontinuation were gastrointestinal complaints (n = 5/9) and drug cost (n = 2/9). CONCLUSION: In this selected group of patients, the majority complied with liraglutide treatment over the initial 4-month period and achieved a significant weight loss, irrespective of the maximally tolerated maintenance dose. Addition of metformin induced a small but significant additional weight loss.

Psychosocial Consequences of Bariatric Surgery: Two Sides of a Coin: a Scoping Review.

This scoping review summarizes current evidence with regard to the impact of bariatric surgery on psychological health in adults with obesity. While a large body of evidence reports major metabolic benefit and improved quality of life, there is also ample evidence suggesting an increased incidence of self-harming behavior, a greater likelihood of developing an alcohol problem and higher rates of completed suicide among bariatric patients. Being able to identify the "at risk" patient population requires more longitudinal research into the risk factors for psychological complications after bariatric surgery. Bariatric surgery remains an extremely valuable long-term treatment option for managing obesity; however, there is a need to invest in mitigating psychological complications after the surgery, such as depression, alcohol consumption, and other self-harming behaviors.

A multicenter propensity score matched analysis in 73,843 patients of an association of nutritional risk with mortality, length of stay and readmission rates.

BACKGROUND: The reported prevalences and effects of nutritional risk vary widely in the literature because of both methodological differences (e.g., screening tools and statistical analyses) and different patient populations. OBJECTIVE: In this study the authors analyzed in-hospital mortality, 30-d mortality, readmission within 4 mo, and justified length of stay (jLoS) (determined by governmental assessment to justify financial compensation) in hospitalized patients nutritionally at risk compared with hospitalized patients not at risk. DESIGN: This was a multicenter retrospective cohort study in 6 Belgian hospitals among inpatients in 2018. Propensity score matching was applied, including comorbidity score and exact matching for hospital, age group, sex, type of admission, living situation, and medical specialty. RESULTS: In total, 73,843 of 85,677 patients were screened at admission, with 16,141 found to have nutritional risk (prevalence of 21.9%). Oncology patients had the highest risk prevalence of 38.3%, whereas patients receiving plastic or reconstructive surgery had a prevalence of 5.2%. Patients nutritionally at risk had higher odds of dying in the hospital (5.1% compared with 3.3%; OR: 1.56; 95% CI: 1.37, 1.76), dying within 30 d of admission (6.8% compared with 4.3%; OR: 1.62; 95% CI: 1.45, 1.81) and being readmitted within 4 mo after discharge (35.5% compared with 32.9%; OR: 1.12; 95% CI: 1.07, 1.18). These differences were consistent across hospitals. The association between being nutritionally at risk and jLoS was ambiguous. CONCLUSIONS: One out of 5 patients included in this study was nutritionally at risk. Using propensity score matching, higher odds of in-hospital mortality, readmission, and 30-d mortality were observed. In contrast to oft-reported increased length of stay with poor nutrition, propensity matched data for jLoS suggested that this association was less pronounced in this cohort.

Impact of COVID-19: urging a need for multi-domain assessment of COVID-19 inpatients.

OBJECTIVE: To retrospectively analyse data obtained from the multi-domain assessment of hospitalized COVID-19 patients, to describe their health status at discharge, and to investigate whether subgroups of patients, more specific ICU patients and older adults (> 70 years), had more (or less) risk to experience specific impairments. METHODS: Retrospective case series in the University Hospitals Leuven, Belgium of confirmed COVID-19 patients 'after surviving an ICU-stay', 'aged ≥ 70 years', or 'aged < 70 years with a length of hospitalization > 7 days'. Exclusion criteria were 'unwilling to cooperate', 'medically unstable', or 'palliative care policy'. Following tests were used: 'Five Times Sit To Stand Test', 'hand grip dynamometry', 'Barthel index', 'Swallowing screening', 'Montreal Cognitive Assessment', 'Hospital Anxiety and Depression Scale', and 'Nutritional Risk Screening 2002'. RESULTS: One or more tests were obtained in 135/163 patients (83.3%). Physical impairments were present in 43.2-82.8% of the patients. Median BI was 10/20 indicating limited self-dependency. Swallow impairments were present in 3/53 (5.7%) and 24/76 (31.6%) had risk of malnutrition. Impaired memory was seen in 26/43 (60.5%) and 22/47 (46.8%) had elevated anxiety/depression scores. Older adults had more physical, functional, and cognitive impairments. ICU patients had a lower hand grip force. CONCLUSION(S): The high prevalence of physical, cognitive, psychological, and functional impairments in hospitalized COVID-19 patients, both ICU and non-ICU patients, indicates that assessment of impairments is imperative. These results imply that rehabilitation and follow-up is essential for these patients. This paper proposes a short, workable assessment composed with known outcome measures to assess different domains of COVID-19 patients.

Reversal of Roux-en-Y Gastric Bypass Fails to Facilitate the Management of Recalcitrant Hypocalcaemia Caused by Primary Hypoparathyroidism.

Roux-en-Y gastric bypass (RYGB) is thought to reduce calcium absorption from the gut. Here, we report the case of a patient with a RYGB, who developed primary hypoparathyroidism after a total thyroidectomy, leading to recalcitrant hypocalcaemia. Despite aggressive oral calcium and calcitriol supplementation, she remained hypocalcaemic and required intravenous (IV) calcium supplementation to control her symptoms, and to keep calcium serum levels within an acceptable range. Teriparatide treatment improved calcium levels marginally. This treatment, however, was poorly tolerated and ultimately stopped by the patient. As a last resort, reversal of RYGB was performed to improve calcium absorption from the gut. Unfortunately, IV calcium supplementation remained necessary. This case illustrates that the reversal of RYGB is not always a guarantee for success in managing recalcitrant hypocalcaemia.

The curious fate of bone following bariatric surgery: bone effects of sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) in mice.

BACKGROUND: Bone loss and increased fracture risk following bariatric surgery has been reported. We investigated whether the two most commonly performed surgeries, sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), lead to bone loss. In addition, we examined whether fortification of the diet with calcium citrate prevents bone loss. METHODS: We used mouse models for SG and RYGB and compared bone loss with a group of sham mice with similar weight loss. All groups were switched at the time of surgery to a low-fat diet (LFD). We also examined whether fortification of the diet with calcium citrate and vitamin D was able to prevent bone loss. RESULTS: At 2 weeks we observed no major bone effects. However, at 8 weeks, both trabecular and cortical bone were lost to the same extent after SG and RYGB, despite increased calcium absorption and adequate serum levels of calcium, vitamin D, and parathyroid hormone (PTH). Diet fortification with calcium citrate and vitamin D was able to partially prevent bone loss. CONCLUSIONS: Both SG and RYGB lead to excess bone loss, despite intestinal adaptations to increase calcium absorption. Fortifying the diet with calcium citrate and vitamin D partly prevented the observed bone loss. This finding emphasizes the importance of nutritional support strategies after bariatric surgery, but also affirms that the exact mechanisms leading to bone loss after bariatric surgery remain elusive and thus warrant further research.

At similar weight loss, dietary composition determines the degree of glycemic improvement in diet-induced obese C57BL/6 mice.

BACKGROUND: Achieving weight loss is the cornerstone of the treatment of the metabolic consequences of obesity, in particular of glucose intolerance. OBJECTIVE: To determine whether improvement in glucose control depends on dietary macronutrient composition of the diet at identical weight loss. MATERIALS AND METHODS: Twenty-two weeks old diet-induced obese C57BL/6 mice lost weight through caloric restriction on normal chow (R-NC) or high fat diet (R-HF). Control mice were fed normal chow (LEAN) or high fat diet (OBESE) ad libitum. Body weight and composition were assessed after 8 weeks of dietary intervention. Glucose homeostasis was evaluated by intraperitoneal glucose tolerance tests (IPGTT). Epididymal white adipose (eWAT) and hepatic tissues were analyzed by immunohistochemistry and RT-qPCR. RESULTS: By 30 weeks of age, the body weight of the mice on R-NC (31.6±1.7g, mean±SEM) and R-HF (32.3±0.9g) was similar to LEAN mice (31.9±1.4g), while OBESE mice weighed 51.7±2.4g. Glucose tolerance in R-NC was better than in LEAN mice (69% AUC IPGTT, P 0.0168) whereas R-HF mice remained significantly less glucose tolerant (125% AUC IPGTT, P 0.0279 vs LEAN), despite identical weight loss. The eWAT pads and adipocyte size were similar in LEAN and R-NC mice, while the eWAT pad size of R-HF was 180% of R-NC (P < 0.0001) and the average adipocyte size of R-HF mice was 134% of R-NC fed mice (P 0.0285). No LEAN or R-NC mice had hepatic steatosis, in contrast to 28.6% of R-HF mice. Compared to OBESE mice, inflammatory markers were lower in eWAT and liver tissue of R-NC, but not in R-HF mice. Measures of visceral adiposity correlated well with glucose tolerance parameters. CONCLUSIONS: In mice, caloric restriction on a normal chow diet improved glucose tolerance significantly more when identical weight loss was achieved on a high fat diet.

Thin bones: Vitamin D and calcium handling after bariatric surgery.

Bariatric surgery has proven to be a valuable treatment option for morbid obesity. However, these procedures can lead to impaired intestinal absorption of calcium and vitamin D, thereby challenging calcium homeostasis and possibly contributing to bone loss leading to an increased fracture risk. Besides calcium and vitamin D malabsorption, hormonal changes occurring after surgery can also be the source of observed bone loss. In this review, first, a case report will be discussed, highlighting the relevance of this topic. Afterwards, changes in bone density and fracture risk, after the two most performed types of bariatric surgery, Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB) will be discussed. In addition, we discuss the putative underlying mechanisms leading to bone changes based on both preclinical and clinical observations. Nonetheless, it is clear further research is needed to further elucidate the exact mechanisms of bone loss following bariatric surgery and subsequently identify potential treatment options for bone preservation.

Neonatal thyroid-stimulating hormone concentrations in Belgium: a useful indicator for detecting mild iodine deficiency?

It has been proposed that neonatal thyroid-stimulating hormone (TSH) concentrations are a good indicator of iodine deficiency in the population. A frequency of neonatal TSH concentrations above 5 mU/L below 3% has been proposed as the threshold indicating iodine sufficiency. The objective of the present study was to evaluate feasibility and usefulness of nation-wide neonatal TSH concentration screening results to assess iodine status in Belgium. All newborns born in Belgium during the period 2009-2011 (n = 377713) were included in the study, except those suffering from congenital hypothyroidism and premature neonates. The frequency of neonatal TSH concentrations above 5 mU/L from 2009 to 2011 in Belgium fluctuated between 2.6 and 3.3% in the centres using the same TSH assay. There was a significant inverse association between neonatal TSH level and birth weight. The longer the duration between birth and screening, the lower the TSH level. Neonatal TSH levels were significantly lower in winter than in spring or autumn and significantly lower in spring and summer than in autumn while significantly higher in spring compared to summer. In conclusion, despite that pregnant women in Belgium are mildly iodine deficient, the frequency of neonatal TSH concentrations above 5 mU/L was very low, suggesting that the neonatal TSH threshold proposed for detecting iodine deficiency needs to be re-evaluated. Although neonatal TSH is useful to detect severe iodine deficiency, it should not be recommended presently for the evaluation of iodine status in mildly iodine deficient regions.

In vitro differentiated adult human liver progenitor cells display mature hepatic metabolic functions: a potential tool for in vitro pharmacotoxicological testing.

The potential use of stem/progenitor cells as alternative cell sources to mature hepatocytes remains basically dependent on their ability to exhibit some, if not all, the metabolic liver functions. In the current study, four major liver functions were investigated in adult derived human liver stem/progenitor cell (ADHLSCs) populations submitted to in vitro hepatogenic differentiation: gluconeogenesis, ammonia detoxification, and activity of phase I and phase II drug-metabolizing enzymes. These acquired hepatic activities were compared to those of primary adult human hepatocytes, the standard reference. Amino acid content was also investigated after hepatogenic differentiation. Differentiated ADHLSCs display higher de novo synthesis of glucose correlated to an increased activity of glucose-6 phosphatase and mRNA expression of key related enzymes. Differentiated ADHLSCs are also able to metabolize ammonium chloride and to produce urea. This was correlated to an increase in the mRNA expression of relevant key enzymes such arginase. With respect to drug metabolism, differentiated ADHLSCs express mRNAs of all the major cytochromes investigated, among which the CYP3A4 isoform (the most important drug-metabolizing enzyme). Such increased expression is correlated to an enhanced phase I activity as independently demonstrated using fluorescence-based assays. Phase II enzyme activity and amino acid levels also show a significant enhancement in differentiated ADHLSCs. The current study, according to data independently obtained in different labs, demonstrates that in vitro differentiated ADHLSCs are able to display advanced liver metabolic functions supporting the possibility to develop them as potential alternatives to primary hepatocytes for in vitro settings.

Defining the pathogenesis of the human Atp12p W94R mutation using a Saccharomyces cerevisiae yeast model.

Studies in yeast have shown that a deficiency in Atp12p prevents assembly of the extrinsic domain (F(1)) of complex V and renders cells unable to make ATP through oxidative phosphorylation. De Meirleir et al. (De Meirleir, L., Seneca, S., Lissens, W., De Clercq, I., Eyskens, F., Gerlo, E., Smet, J., and Van Coster, R. (2004) J. Med. Genet. 41, 120-124) have reported that a homozygous missense mutation in the gene for human Atp12p (HuAtp12p), which replaces Trp-94 with Arg, was linked to the death of a 14-month-old patient. We have investigated the impact of the pathogenic W94R mutation on Atp12p structure/function. Plasmid-borne wild type human Atp12p rescues the respiratory defect of a yeast ATP12 deletion mutant (Deltaatp12). The W94R mutation alters the protein at the most highly conserved position in the Pfam sequence and renders HuAtp12p insoluble in the background of Deltaatp12. In contrast, the yeast protein harboring the corresponding mutation, ScAtp12p(W103R), is soluble in the background of Deltaatp12 but not in the background of Deltaatp12Deltafmc1, a strain that also lacks Fmc1p. Fmc1p is a yeast mitochondrial protein not found in higher eukaryotes. Tryptophan 94 (human) or 103 (yeast) is located in a positively charged region of Atp12p, and hence its mutation to arginine does not alter significantly the electrostatic properties of the protein. Instead, we provide evidence that the primary effect of the substitution is on the dynamic properties of Atp12p.

Subcomplexes of mitochondrial complex V reveal mutations in mitochondrial DNA.

Complex V, site of the final step in oxidative phosphorylation, uses the proton gradient across the inner mitochondrial membrane for the production of ATP. It is a multi-subunit complex composed of a catalytic domain (F(1)) and a membrane domain (F(0)) linked by two stalks. Subcomplexes of complex V containing the F(1) domain have previously been reported in small series of patients. We report the results in tissue samples and/or cultured skin fibroblasts studied by blue native PAGE followed by activity staining in the gel. Catalytically active subcomplexes of complex V were detected in 66 tissues originating from 53 patients. In 29 of the latter (55%), a mitochondrial DNA (mtDNA) defect was identified. Twelve patients had a pathogenic point mutation in a mitochondrial tRNA, one a large mtDNA deletion, 12 showed mtDNA depletion and four had a mutation in the MT-ATP6 gene. We conclude that the presence of subcomplexes of complex V is a valuable indicator in the detection of mtDNA defects.

The aerobic forearm exercise test, a non-invasive tool to screen for mitochondrial disorders.

The diagnosis of a mitochondrial disorder is often difficult. Therefore, new approaches and diagnostic criteria are being developed. One of these tests is the aerobic forearm exercise test, a screening tool that can contribute to assess whether or not the patient suffers from a mitochondrial myopathy. With this simple, non-invasive test, the oxidative metabolism of muscle can be evaluated in rest and during exercise. We performed the aerobic forearm exercise test in patients with a mitochondrial disorder and an identified pathogenic gene mutation, in patients with a suspected mitochondrial disorder based on their clinical presentation and biochemical results, but without a molecular diagnosis, and in patients with atypical fatigue and no characteristics of a mitochondrial myopathy. In the first two groups, abnormal oxygen extraction from the blood during exercise was observed in four out of twelve patients. In the third group no abnormalities were found. The number of patients that we could test so far was limited, but all the patients experienced the aerobic forearm exercise as an easy test. We would like to stimulate clinicians to perform this test whenever a mitochondrial myopathy is suspected, as it can be a valuable diagnostic screening tool.

Two novel mitochondrial DNA mutations in muscle tissue of a patient with limb-girdle myopathy.

BACKGROUND: Defects in the oxidative phosphorylation system can cause a broad spectrum of clinical symptoms ranging from an isolated myopathy to a multisystemic disorder. OBJECTIVE: To study and identify the underlying molecular defect in a patient with limb-girdle myopathy. DESIGN: Biochemical, histochemical, and immunocytochemical analyses were performed in combination with polymerase chain reaction-single-strand conformation polymorphism and restriction fragment length polymorphism-polymerase chain reaction techniques. SETTING: University hospital. PATIENT: A 48-year-old woman with limb-girdle myopathy. MAIN OUTCOME MEASURES: The pathogenic characteristics of the identified nucleotide alterations were defined using single-muscle fiber analysis. RESULTS: A complex III deficiency was detected using blue native-polyacrylamide gel electrophoresis, while immunocytochemical results showed a mosaic staining pattern for complexes I and IV. After molecular analyses, 2 novel heteroplasmic mitochondrial DNA (mtDNA) nucleotide aberrations, m.5888insA and m.14639A>G, were identified in muscle tissue. Single-muscle fiber analyses demonstrated that cytochrome c oxidase-deficient fibers, compared with cytochrome c oxidase-positive fibers, harbored statistically significantly higher levels of both mtDNA mutations (P < .001, t test). CONCLUSIONS: These results, together with previously defined canonical criteria determining the pathogenic characteristics of mtDNA mutations, suggest that both nucleotide changes are pathogenic mutations. To our knowledge, this is only the third report of the coexistence of 2 pathogenic mtDNA mutations present in different genes within individual skeletal muscle fibers of a patient.

A new family with the mitochondrial tRNAGLU gene mutation m.14709T>C presenting with hydrops fetalis.

BACKGROUND: In the heterogeneous group of mitochondrial disorders, patients with the same genotype can show different phenotypes and the same phenotype can be caused by different genotypes. We describe a family with the m.14709T>C mutation and a clinical presentation of hydrops fetalis, in contrast to previous reports in which patients presented with myopathy and/or diabetes mellitus. AIM: To identify a mutation in the mtDNA of a family with a heterogeneous clinical presentation. METHODS: Both biochemical and molecular analyses were performed. RESULTS: Biochemical results showed a decreased complex I and IV activity in muscle tissue of the patients. A mosaic-staining pattern for complex I in the patients' fibroblasts was revealed using immunocytochemistry. Molecular analyses identified the m.14709T>C mutation in the mitochondrial encoded tRNA(Glu) gene. CONCLUSION: We report 2 siblings with the m.14709T>C mutation in the mitochondrial tRNA(Glu) gene. The first patient showed hydrops fetalis, a new presentation within the clinical spectrum of this mutation, and the other a known presentation namely mild myopathy.

A novel mitochondrial transfer RNA(Asn) mutation causing multiorgan failure.

BACKGROUND: Mitochondrial cytopathies are a heterogeneous group of disorders with a broad spectrum of clinical symptoms. OBJECTIVE: To characterize a novel mutation in the transfer RNA(Asn) (m.5728A>G) identified in a 13-year-old boy with multiorgan failure. DESIGN: Biochemical and immunocytochemical studies were performed in combination with transmitochondrial cybrid analysis. SETTING: A university hospital. Molecular and biochemical analyses were performed in collaboration between 2 other university hospitals. PATIENT: Thirteen-year-old boy with multiorgan failure. RESULTS: In the patient's muscle tissue and cultured skin fibroblasts, a combined deficiency of complexes I and IV was found, using spectrophotometric analysis and activity staining in the gel following blue native polyacrylamide gel electrophoresis. An identical biochemical profile was seen in transmitochondrial cybrids carrying more than 55% mutant mitochondrial DNA. CONCLUSION: These data suggest that the m.5728A>G transition is a pathogenic mutation and is the cause of the respiratory chain dysfunction in the propositus.

Serotonergic modulation of murine fundic tone.

Fundic tone is maintained through a balance of excitatory and inhibitory input to fundic smooth muscle. The aim of this study was to determine the role of serotonin (5-HT) and 5-HT receptors in modulating murine fundic tone. Muscle strips were prepared from the murine fundus. Intracellular recordings were made from circular smooth muscle cells, and the effects of 5-HT on tone and excitatory and inhibitory junction potentials evoked by electrical field stimulation (EFS) were determined. 5-HT induced a concentration-dependent contraction and smooth muscle depolarization that was tetrodotoxin resistant. The 5-HT(1B/D) receptor antagonists GR-127935 and BRL-155172 significantly inhibited 5-HT-induced contractions. The 5-HT(1B/D) agonist sumatriptan contracted murine fundic muscle. The 5-HT(1A) receptor agonist buspirone relaxed fundic smooth muscle, and the relaxation was inhibited by WAY-100135 but not by N(omega)-nitro-l-arginine or tetrodotoxin. 5-HT enhanced both the excitatory and inhibitory responses to EFS. The 5-HT(3) receptor antagonist MDL-72222 partly inhibited both the excitatory and inhibitory response elicited by EFS, whereas the 5-HT(4) receptor antagonist GR-113808 partly inhibited the EFS-evoked inhibitory response. The 5-HT reuptake inhibitor fluoxetine contracted smooth muscle strips, a contraction that was partially inhibited by GR-127935 and abolished by tetrodotoxin. In conclusion, the data suggest that 5-HT modulates murine fundic contractile activity through several different receptor subtypes. Sustained release of 5-HT maintains fundic tone through postjunctional 5-HT(1B/D) receptors. 5-HT(3) receptors modulate excitatory neural input to murine fundic smooth muscle, and both 5-HT(3) and 5-HT(4) receptors modulate inhibitory neural input to murine fundic smooth muscle.