HIF-PHD inhibitor desidustat ameliorates iron deficiency anemia

Iron deficiency anemia is caused by many pathological conditions like chronic kidney disease (CKD), inflammation, malnutrition and gastrointestinal abnormality. Current treatments that are erythropoiesis stimulating agents (ESAs) and iron supplementation are inadequate and often lead to tolerance and/or toxicity. Desidustat, a prolyl hydroxylase (PHD) inhibitor, is clinically used for the treatment of anemia with CKD. In this study, we investigated the effect of desidustat on iron deficiency anemia (IDA). IDA was induced in C57BL6/J mice by iron deficient diet feeding. These mice were then treated with desidustat (15 mg/kg, PO) and FeSO4 (20 mg/kg) for five weeks and effect of the treatment on hematology, iron homeostasis, and bone marrow histology was observed. Effect of desidustat on iron metabolism in inflammation (LPS)-induced iron deficiency was also assessed. Both, Desidustat and FeSO4, increased MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), hemoglobin, and HCT (hematocrit) in blood and increased iron in serum, liver, and spleen. Desidustat increased MCHC (mean corpuscular hemoglobin concentration) while FeSO4 treatment did not alter it. FeSO4 treatment significantly increased iron deposition in liver, and spleen, while desidustat increased iron in circulation and demonstrated efficient iron utilization. Desidustat increased iron absorption, serum iron and decreased hepcidin without altering tissue iron, while FeSO4 increased serum and tissue iron by increasing hepcidin in LPS-induced iron deficiency. Desidustat increased erythroid population, especially iron-dependent polychromatic normoblasts and orthochromatic normoblasts, while FeSO4 did not improve cell architecture. PHD inhibition by desidustat improved iron utilization in iron deficiency anemia, by efficient erythropoiesis.

Impact of variation in practice in the prenatal reporting of variants of uncertain significance by commercial laboratories: NEED FOR GREATER ADHERENCE TO PUBLISHED GUIDELINES

OBJECTIVE

To evaluate the impact of implementing commercial whole exome sequencing (WES) and targeted gene panel testing in pregnancies with fetal anomalies.

METHODS

A retrospective chart review of 124 patients with sequencing performed by commercial laboratories.

RESULTS

The diagnostic yield of WES and panel testing was 21.5% and 26% respectively, based on likely pathogenic (LP) or pathogenic (P) variants. Forty-two per cent of exomes and 32% of panels analyzed had one or more variant of uncertain significance (VUS) reported. A multidisciplinary in depth review of the fetal phenotype, disease phenotype, variant data, and, in some patients, additional prenatal or postnatal investigations increased the diagnostic yield by 5% for exome analysis and 6% for panel analysis.

CONCLUSIONS

The diagnostic yield of WES and panel testing combined was 23% based on LP and P variants. Although the reporting of VUS contributed to a 5% increase in diagnostic yield for WES and 6% for panels, the large number of VUS reported by commercial laboratories has significant resource implications. Our results support the need for greater adherence to the recommendations on the prenatal reporting of VUS and the importance of a multidisciplinary approach that brings together clinical and laboratory expertise in prenatal genetics and genomics. This article is protected by copyright. All rights reserved.

Prolyl hydroxylase inhibitor desidustat improves anemia in erythropoietin hyporesponsive state

Many anemic chronic kidney disease (CKD) patients are refractory to erythropoietin (EPO) effects due to inflammation, deranged iron utilization, and generation of EPO antibodies. This work assessed the effect of desidustat, an inhibitor of hypoxia inducible factor (HIF) prolyl hydroxylase (PHD), on EPO-refractory renal anemia. Sprague Dawley rats were made anemic by cisplatin (5 ​mg/kg, IP, single dose) and turpentine oil (5 ​mL/kg, SC, once a week). These rats were given recombinant human EPO (rhEPO, 1 ​μg/kg) and desidustat (15 or 30 ​mg/kg) for eight weeks. Separately, rhEPO (1–5 ​μg/kg) was given to anemic rats to sustain the normal hemoglobin levels and desidustat (15 ​mg/kg) for eight weeks. In another experiment, the anemic rats were treated rhEPO (5 ​μg/kg) for two weeks and then desidustat (15 ​mg/kg) for the next two weeks. Dosing of rhEPO was thrice a week, and for desidustat, it was on alternate days. Desidustat inhibited EPO-resistance caused by rhEPO treatment, decreased hepcidin, IL-6, IL-1β, and increased iron and liver ferroportin. Desidustat reduced EPO requirement and anti-EPO antibodies. Desidustat also maintained normal hemoglobin levels after cessation of rhEPO treatment. Thus, novel prolyl hydroxylase inhibitor desidustat can treat EPO resistance via improved iron utilization and decreased inflammation.

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Prolyl hydroxylase inhibitor desidustat reduces rhEPO requirement in anemia.

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Desidustat maintains normal haemoglobin after discontinuation of rhEPO treatment.

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The drug increases erythropoiesis by increasing endogenous EPO and reducing EPO-resistance.

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It also enhances erythroid maturation by suppressing hepcidin-ferroportin axis.

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Desidustat improves EPO-sensitivity by decreasing IL-6, IL-1β, and anti-EPO antibodies.

Effect of dual PPAR-α/γ agonist saroglitazar on diabetic retinopathy and oxygen-induced retinopathy

Diabetic retinopathy is a serious complication of diabetes, marked by retinal vascular damage, inflammation, and angiogenesis. This study's objective was to assess the potential benefits of saroglitazar, a peroxisome proliferator-activated receptor-alpha/gamma (PPAR-α/γ) agonist in diabetic retinopathy. Diabetic retinopathy was induced by streptozotocin in Sprague Dawley rats. The effect of saroglitazar was also assessed in the oxygen-induced retinopathy model in newborn rats and VEGF-induced angiogenesis in the chick chorioallantoic membrane (CAM) assay. Treatment of saroglitazar (1 and 4 mg/kg, oral) for 12 weeks significantly ameliorated retinal vascular leakage and leukostasis in the diabetic rats. Saroglitazar decreased oxidative stress, VEGF receptor signalling, NF-κBp65, and ICAM-1 in the retina of diabetic rats. The beneficial effects of saroglitazar (1 and 4 mg/kg, oral) were also observed on the neovascularization in oxygen-induced retinopathy in newborn rats. Saroglitazar also reduced VEGF-induced angiogenesis in CAM assay. This study reveals that saroglitazar has the potential to prevent the progression of retinopathy in diabetic patients.

The effects of cesium lead bromide quantum dots on the performance of copper phthalocyanine-based organic field-effect transistors

Highly luminescent all-inorganic cesium lead bromide (CsPbBr₃) perovskite quantum dots (QDs) have been extensively used as a photosensitizer in optoelectronic devices, while p-type small-organic-molecule copper phthalocyanine (CuPc) is also widely used as a photoactive material in solar cells, organic field-effect transistors (OFETs), etc. In this paper, we report the preparation of a CsPbBr₃-QDs/CuPc heterostructure to study the effect of CsPbBr₃-QDs on CuPc. The optical properties of both CuPc and the QDs/CuPc heterostructure were compared and contrasted using UV-vis absorbance and photoluminescence (PL) measurements. Furthermore, to study their electronic and charge transfer features, we fabricated field-effect transistors (FETs) on both pristine CuPc and QDs/CuPc heterostructure thin films and studied their photoresponsive electrical characteristics. Both pristine and QDs/CuPc-based FETs showed an enhancement in current and carrier mobility under illumination. The enhancement in the current and carrier mobility of the QDs/CuPc-based FETs is due to a large number of photoexcited charge carriers. We also observed that the current and carrier mobility in the QDs/CuPc heterostructure-based FET were lower than those of the pristine CuPc-based FET. This can be explained by the n-type doping effect of CsPbBr₃ QDs on CuPc, which reduces the accumulation of holes in the active p-channel near the insulating layer and causes charge to be transferred from the QDs to the CuPc. Thus, we have observed a charge transfer effect in the CsPbBr₃ QDs/CuPc heterostructure, which can be used in optoelectronic devices.

Prolyl hydroxylase inhibitor desidustat protects against acute and chronic kidney injury by reducing inflammatory cytokines and oxidative stress

Chronic kidney disease (CKD) is associated with activated inflammatory responses. Desidustat, a prolyl hydroxylase (PHD) inhibitor is useful for treatment of anemia associated with CKD, but its effect on the inflammatory and fibrotic changes in CKD is not evaluated. In this study, we investigated the effect of desidustat on the inflammatory and fibrotic changes in preclinical models of acute and chronic kidney injury. Acute kidney injury was induced in male Sprague Dawley rats by ischemia-reperfusion, in which effect of desidustat (15 mg/kg, PO) was estimated. In a separate experiment, male C57 mice were treated with adenine for 14 days to induce CKD. These mice were treated with desidustat (15 mg/kg, PO, alternate day) treatment for 14 days, with adenine continued. Desidustat prevented elevation of serum creatinine, urea, IL-1β, IL-6, and kidney injury molecule-1 (KIM-1), and elevated the erythropoietin levels in rats that were subjected to acute kidney injury. Mice treated with adenine developed CKD and anemia, and desidustat treatment caused improvement in serum creatinine, urea, and also improved hemoglobin and reduced hepatic and serum hepcidin. A significant reduction in IL-1β, IL-6, myeloperoxidase (MPO) and oxidative stress was observed by desidustat treatment. Desidustat treatment also reduced renal fibrosis as observed by histological analysis and hydroxyproline content. Desidustat treatment reduced the renal fibrosis and inflammation along with a reduction in anemia in preclinical models of kidney injury, which may translate to protective effects in CKD patients.

Early presentation of ruptured post-traumatic hepatic artery pseudoaneurysm

Visceral artery aneurysms (VAA) are an uncommon but well recognized condition. Hepatic artery aneurysms (HAA) represent 14-20% of all visceral artery aneurysms. Post traumatic hepatic artery pseudoaneurysm is an uncommon delayed complication of blunt liver trauma. Here we present a case of a 27 year old male with blunt abdominal trauma who developed a post traumatic pseudoaneurysm of the hepatic artery just proximal to its bifurcation into the left and right branches. The pseudoaneurysm ruptured within 12 hours of injury and he required double ligation of the hepatic artery as well as right and left hepatic arteries. However, the bleeding continued through the retrograde flow from the gastroduodenal artery and hence, ligation of gastrodudenal artery was also done. The decision of complete devasularisation of liver was taken as an emergency lifesaving procedure. The patient recovered and was discharged without sequel.

Activation of GLP-1 and Glucagon Receptors Regulates Bile Homeostasis Independent of Thyroid Hormone

BACKGROUND

Balanced coagonists of glucagon-like peptide-1 (GLP-1) and glucagon receptors are emerging therapies for the treatment of obesity and diabetes. Such coagonists also regulate lipid metabolism, independent of their body weight lowering effects. Many actions of the coagonists are partly mediated by fibroblast growth factor 21 (FGF21) signaling, with the major exception of bile homeostasis. Since thyroid hormone is an important regulator of bile homeostasis, we studied the involvement of thyroid hormone in coagonist-induced changes in lipid and bile metabolism.

METHODS

We evaluated the effect of a single dose of coagonist Aib2 C24 chimera2 at 150 to 10000 µg/kg on tetraiodothyronine (T4) and triiodothyronine (T3) in high-fat diet-induced obese (DIO) mice and chow-fed mice. Repeated dose treatment of coagonist (150 µg/kg, subcutaneously) was assessed in four mice models namely, on lipid and bile homeostasis in DIO mice, propylthiouracil (PTU)-treated DIO mice, methimazole (MTM)-treated DIO mice and choline-deficient, L-amino acid-defined, highfat diet (CDAHFD)-induced nonalcoholic steatohepatitis (NASH).

RESULTS

Single dose treatment of coagonist did not alter serum T3 and T4 in chow-fed mice and DIO mice. Coagonist treatment improved lipid metabolism and biliary cholesterol excretion. Chronic treatment of GLP-1 and glucagon coagonist did not alter serum T3 in hypothyroid DIO mice and CDAHFDinduced NASH. Coagonist increased serum T4 in DIO mice after 4 and 40 weeks of treatment, though no change in T4 levels was observed in hypothyroid mice or mice with NASH.

CONCLUSION

Our data demonstrate that coagonist of GLP-1 and glucagon receptors does not modulate bile homeostasis via thyroid signaling.

Coagonist of glucagon-like peptide-1 and glucagon receptors ameliorates kidney injury in murine models of obesity and diabetes mellitus

AIM

To investigate the role of glucagon-like peptide-1 (GLP-1)/glucagon receptors coagonist on renal dysfunction associated with diabetes and obesity.

METHODS

Chronic high-fat diet fed C57BL/6J mice, streptozotocin-treated high-fat diet fed C57BL/6J mice and diabetic C57BLKS/J db/db mice were used as models of diabetes-induced renal dysfunction. The streptozotocin-treated high-fat diet fed mice and db/db mice were treated with the GLP-1 and glucagon receptors coagonist (Aib2 C24 Chimera2, 150 μg/kg, sc) for twelve weeks, while in chronic high-fat diet fed mice, coagonist (Aib2 C24 Chimera2, 150 μg/kg, sc) treatment was continued for forty weeks. Kidney function, histology, fibrosis, inflammation, and plasma biochemistry were assessed at the end of the treatment.

RESULTS

Coagonist treatment decreased body weight, plasma lipids, insulin resistance, creatinine, blood urea nitrogen, urinary albumin excretion rate and renal lipids. In kidney, expression of lipogenic genes (SREBP-1C, FAS, and SCD-1) was decreased, and expression of genes involved in β-oxidation (CPT-1 and PPAR-α) was increased due to coagonist treatment. In plasma, coagonist treatment increased adiponectin and FGF21 and decreased IL-6 and TNF-α. Coagonist treatment reduced expression of inflammatory (TNF-α, MCP-1, and MMP-9) and pro-fibrotic (TGF-β, COL1A1, and α-SMA) genes and also improved histological derangement in renal tissue.

CONCLUSION

Coagonist of GLP-1 and glucagon receptors alleviated diabetes and obesity-induced renal dysfunction by reducing glucose intolerance, obesity, and hyperlipidemia.

Incidence of clinically suspected venous thromboembolism in British Indian patients

Introduction Venous thromboembolism (VTE) remains a major public health issue around the world. Ethnicity is known to alter the incidence of VTE. To our knowledge, there are no reports in the literature investigating the incidence of VTE in British Indians. The aim of this study was to investigate the rates of symptomatic VTE in British Indian patients in the UK. Methods Patients referred to our institution between January 2011 and August 2013 with clinically suspected VTE were eligible for inclusion in the study. Those not of British Indian or Caucasian ethnicity were excluded. A retrospective review of these two cohorts was conducted. Results Overall, 15,529 cases were referred to our institution for suspected VTE. This included 1,498 individuals of British Indian ethnicity. Of these, 182 (12%) had confirmed VTE episodes. A further 13,159 of the patients with suspected VTE were coded as Caucasian, including 2,412 (16%) who had confirmed VTE events. VTE rates were a third lower in British Indians with clinically suspected VTE than in the equivalent Caucasian group. The British Indian cohort presented with VTE at a much earlier age than Caucasians (mean 57.0 vs 68.0 years). Conclusions This study suggests that British Indian patients have a lower incidence of VTE and are more likely to present at an earlier age than Caucasians. There was no significant difference in VTE type (deep vein thrombosis vs pulmonary embolism) among the ethnic groups. Clinicians should be aware of variations within ethnicities but should continue to adhere to existing VTE prevention guidance.

Prolonged Survival Following Pig-to-Primate Liver Xenotransplantation Utilizing Exogenous Coagulation Factors and Costimulation Blockade

Since the first attempt of pig-to-primate liver xenotransplantation (LXT) in 1968, survival has been limited. We evaluated a model utilizing α-1,3-galactosyltransferase knockout donors, continuous posttransplant infusion of human prothrombin concentrate complex, and immunosuppression including anti-thymocyte globulin, FK-506, methylprednisone, and costimulation blockade (belatacept, n = 3 or anti-CD40 mAb, n = 1) to extend survival. Baboon 1 remained well until postoperative day (POD) 25, when euthanasia was required because of cholestasis and plantar ulcers. Baboon 2 was euthanized following a seizure on POD 5, despite normal liver function tests (LFTs) and no apparent pathology. Baboon 3 demonstrated initial stable liver function but was euthanized on POD 8 because of worsening LFTs. Pathology revealed C4d positivity, extensive hemorrhagic necrosis, and a focal cytomegalovirus inclusion. Baboon 4 was clinically well with stable LFTs until POD29, when euthanasia was again necessitated by plantar ulcerations and rising LFTs. Final pathology was C4d negative and without evidence of rejection, inflammation, or thrombotic microangiopathy. Thus, nearly 1-mo rejection-free survival has been achieved following LXT in two of four consecutive recipients, demonstrating that the porcine liver can support life in primates for several weeks and has encouraging potential for clinical application as a bridge to allotransplantation for patients with acute-on-chronic or fulminant hepatic failure.

Klotho and smoking--An interplay influencing the skeletal muscle function deficits that occur in COPD

BACKGROUND

Klotho is an 'anti-ageing' hormone and transmembrane protein; Klotho deficient mice develop a similar ageing phenotype to smokers including emphysema and muscle wasting. The objective of this study was to evaluate skeletal muscle and circulating Klotho protein in smokers and COPD patients and to relate Klotho levels to relevant skeletal muscle parameters. We sought to validate our findings by undertaking complimentary murine studies.

METHODS

Fat free mass, quadriceps strength and spirometry were measured in 87 participants (61 COPD, 13 'healthy smokers' and 13 never smoking controls) in whom serum and quadriceps Klotho protein levels were also measured. Immunohistochemistry was performed to demonstrate the location of Klotho protein in human skeletal muscle and in mouse skeletal muscle in which regeneration was occurring following injury induced by electroporation. In a separate study, gastrocnemius Klotho protein was measured in mice exposed to 77 weeks of smoke or sham air.

RESULTS

Quadriceps Klotho levels were lower in those currently smoking (p = 0.01), irrespective of spirometry, but were not lower in patients with COPD. A regression analysis identified current smoking status as the only independent variable associated with human quadriceps Klotho levels, an observation supported by the finding that smoke exposed mice had lower gastrocnemius Klotho levels than sham exposed mice (p = 0.005). Quadriceps Klotho levels related to local oxidative stress but were paradoxically higher in patients with established muscle wasting or weakness; the unexpected relationship with low fat free mass was the only independent association. Within locomotor muscle, Klotho localized to the plasma membrane and to centralized nuclei in humans and in mice with induced muscle damage. Serum Klotho had an independent association with quadriceps strength but did not relate to quadriceps Klotho levels or to spirometric parameters.

CONCLUSIONS

Klotho is expressed in skeletal muscle and levels are reduced by smoking. Despite this, quadriceps Klotho protein expression in those with established disease appears complex as levels were paradoxically elevated in COPD patients with established muscle wasting. Whilst serum Klotho levels were not reduced in smokers or COPD patients and were not associated with quadriceps Klotho protein, they did relate to quadriceps strength.

The Impact of Hydroxyethyl Starch Use in Deceased Organ Donors on the Development of Delayed Graft Function in Kidney Transplant Recipients: A Propensity-Adjusted Analysis

Our objective was to evaluate the impact of hydroxyethyl starch (HES) use in organ donors after neurologic determination of death (DNDD) on recipient renal graft outcomes. The following data elements were prospectively collected for every DNDD managed by a single organ procurement organization from June 2011 to July 2013: demographics; critical care endpoints; treatments, including the use of HES; graft cold ischemia time (CIT); and the occurrence of recipient delayed graft function (DGF, dialysis in the first week after transplantation). Logistic regression was performed to identify independent predictors of DGF with a p-value <0.05. The results were then adjusted for each donor's calculated propensity to receive HES. Nine hundred eighty-six kidneys were transplanted from 529 donors. Forty-two percent received HES (1217 ± 528 mL) and 35% developed DGF. Kidneys from DNDDs who received HES had a higher crude rate of DGF (41% vs. 31%, p < 0.001). After accounting for the propensity to receive HES, independent predictors of DGF were age (OR 1.02 [1.01-1.04] per year), CIT (OR 1.04[1.02-1.06] per hour), creatinine (OR 1.5 [1.32-1.72] per mg/dL) and HES use (OR 1.41 [1.02-1.95]). HES use during donor management was independently associated with a 41% increase in the risk of DGF in kidney transplant recipients.

Dashboard (in the) knee

We present the case of a 19-year-old individual presenting to an orthopaedic outpatient clinic several months following a dashboard knee injury during a road traffic accident with intermittent mechanical symptoms. Despite unremarkable examination findings and normal magnetic resonance imaging, the patient was identified subsequently as having an intra-articular plastic foreign body consistent with a piece of dashboard on arthroscopic knee assessment, the retrieval of which resulted in a complete resolution of symptoms.

Strabismus genetics across a spectrum of eye misalignment disorders

Eye misalignment, called strabismus, is amongst the most common phenotypes observed, occurring in up to 5% of individuals in a studied population. While misalignment is frequently observed in rare complex syndromes, the majority of strabismus cases are non-syndromic. Over the past decade, genes and pathways associated with syndromic forms of strabismus have emerged, but the genes contributing to non-syndromic strabismus remain elusive. Genetic testing for strabismus risk may allow for earlier diagnosis and treatment, as well as decreased frequency of surgery. We review human and model organism literature describing non-syndromic strabismus, including family, twin, linkage, and gene expression studies. Recent advances in the genetics of Duane retraction syndrome are considered, as relatives of those impacted show elevated familial rates of non-syndromic strabismus. As whole genome sequencing efforts are advancing for the discovery of the elusive strabismus genes, this overview is intended to support the interpretation of the new findings.

Study on the mechanism of the bronchodilatory effects of Cynodon dactylon (Linn.) and identification of the active ingredient

ETHNOPHARMACOLOGICAL RELEVANCE

In the traditional medicine, Cynodon dactylon (Linn.) is used in asthma, but scientific studies to provide evidence for medicinal uses are sparse. Thus this study was undertaken to provide evidence for medicinal use in asthma as a bronchodilator, and to identify active ingredient(s).

MATERIALS AND METHODS

In vivo, acetylcholine (Ach)-induced bronchospasm was conducted in guinea pig while isolated rat tracheal strip was suspended in organ bath to measure the concentration response curve using multichannel data acquisition system.

RESULTS

The chloroform extract of Cynodon dactylon (CECD) protected against Ach-induced bronchospasm in guinea pigs, similar to atropine. In the in vitro studies, CECD relaxed carbachol (CCh) and high K+-induced contraction of rat tracheal strip, similar to atropine and verapamil respectively, suggesting antimuscarinic and calcium channel blocking (CCB) activities, which were confirmed by right ward shifting of CCh and Ca(+2) concentration response curve (CRC). The phosphodiestrase (PDE) inhibitory activity was confirmed by potentiation of isoprenaline-induced inhibitory response, similar to papaverine. Densitometry analyses led to the identification of scopoletin as an active ingredient. Effectively, it significantly inhibited high K+, and Ca(+2) induced contractile response, similar to verapamil. The phosphodiestrase (PDE) inhibitory activity was confirmed by direct evidence of potentiation of isoprenaline-induced inhibitory response, similar to papaverine.

CONCLUSIONS

These results suggest that the bronchodilator activity of CECD is partly due to presence of scopoletin, and mediated possibly through CCB and PDE inhibition.

Are soft tissue measurements on lateral cervical spine X-rays reliable in the assessment of traumatic injuries?

INTRODUCTION

Traumatic neck pain is a common presentation to the emergency department. Lateral plain radiographs remain the primary investigation in the assessment of these injuries. Soft tissue assessment forms an integral component of these radiographs. They can provide information on subtle injuries that may not be obvious. Many methods are used to assess the prevertebral soft tissue shadows. The two more commonly used techniques include the 'seven at two and two at seven' rule (method 1) and the ratio of the soft tissues with respect to the vertebral width (method 2).

AIM

To assess which of the above two methods in assessing cervical spine soft tissue shadows on lateral radiographs is more sensitive in the presence of cervical spine injuries.

METHODS

A retrospective analysis of consecutive traumatic cervical spine films performed within a busy trauma tertiary centre over a period of 7 months. Patients were divided into two groups: group 1-fractures; group 2-no fractures. The prevertebral soft tissue shadows were measured at referenced points on the lateral cervical spine films with respect to the above two methods and comparisons between the groups were made.

RESULTS

Thirty-nine patients in group 1 were compared to a control group of 60 patients in group 2. Both methods failed to identify any significant differences between the two groups. The sensitivity and specificity for method 1 was 7.6 and 93 %, and for method 2, they were 7.6 and 98 %, respectively.

CONCLUSION

There is no significant difference between the soft tissue shadows when comparing patients with and without cervical spine fractures on lateral radiographs. Both commonly used measures of soft tissue shadows in clinical practice are insensitive in identifying patients with significant osseous injuries. They, therefore, do not offer any further value in interpreting traumatic cervical spine radiographs. The management of patients with cervical spine trauma in the absence of obvious osseous injury on standard radiographs should warrant a computed tomography (CT) scan if clinically indicated.

Evidence of ancillary trigeminal innervation of levator palpebrae in the general population

The cranial synkineses are a group of disorders encompassing a variety of involuntary co-contractions of the facial, masticatory, or extraocular muscles that occur during a particular volitional movement. The neuroanatomical pathways for synkineses largely remain undefined. Our studies explored a normal synkinesis long observed in the general population - that of jaw opening during efforts to open the eyelids widely. To document this phenomenon, we observed 186 consecutive participants inserting or removing contact lenses to identify jaw opening. Seeking electrophysiological evidence, in a second study we enrolled individuals undergoing vascular decompression for trigeminal neuralgia or hemifacial spasm, without a history of jaw-winking, ptosis, or strabismus, to record any motor responses in levator palpebrae superioris (LPS) upon stimulation of the trigeminal motor root. Stimulus was applied to the trigeminal motor root while an electrode in levator recorded the response. We found that 37 participants (20%) opened their mouth partially or fully during contact lens manipulation. In the second study, contraction of LPS with trigeminal motor stimulation was documented in two of six patients, both undergoing surgery for trigeminal neuralgia. We speculate these results might provide evidence of an endogenous synkinesis, indicating that trigeminal-derived innervation of levator could exist in a significant minority of the general population. Our observations demonstrate plasticity in the human cranial nerve innervation pattern and may have implications for treating Marcus Gunn jaw-winking.

The impact of meeting donor management goals on the development of delayed graft function in kidney transplant recipients

Many organ procurement organizations (OPOs) utilize preset critical care endpoints as donor management goals (DMGs) in order to standardize care and improve outcomes. The objective of this study was to determine the impact of meeting DMGs on delayed graft function (DGF) in renal transplant recipients. All eight OPOs of the United Network for Organ Sharing Region 5 prospectively implemented nine DMGs in every donor after neurologic determination of death (DNDD). "DMGs met" was defined a priori as achieving any seven of the nine DMGs and this was recorded at the time of consent for donation to reflect donor hospital ICU management, 12-18 h later, and prior to organ recovery. Multivariable analyses were performed to identify independent predictors of DGF (dialysis in the first week after transplantation) with a p<0.05. A total of 722 transplanted kidneys from 492 DNDDs were included. A total of 28% developed DGF. DMGs were met at consent in 14%, 12-18 h in 32% and prior to recovery in 38%. DGF was less common when DMGs were met at consent (17% vs. 30%, p=0.007). Independent predictors of DGF were age, Cr and cold ischemia time, while meeting DMGs at consent was significantly protective. The management of potential organ donors prior to consent affects outcomes and should remain a priority in the intensive care unit.

Does the use of a "track and trigger" warning system reduce mortality in trauma patients?

INTRODUCTION

Despite the lack of robust evidence, numerous different "track and trigger" warning systems have been implemented. These have only been validated in an emergency medical admissions setting. The Modified Early Warning Score (MEWS) is the chosen track and trigger system used in the University Hospitals of Leicester trauma unit, but has not been validated in trauma patients. A considerable proportion of all trauma admissions are elderly patients with proximal femoral fractures and significant co-morbidities. Early recognition of physiological deterioration and prompt action could therefore be lifesaving in this patient group.

AIM

To identify whether the implementation of the MEWS system coupled with a critical care outreach service resulted in a reduction in mortality in a busy trauma unit.

METHOD

A retrospective study. The MEWS system was implemented in all trauma and orthopaedic wards at the Leicester Royal Infirmary in the summer of 2005. The numbers of emergency trauma inpatient admissions and deaths from January 2002 to December 2009 were obtained. The diagnosis, primary procedures and cause of death, if known, were noted. Comparisons were made pre- and post-MEWS. Student's t-test was used for statistical analysis.

RESULTS

32,149 patients were admitted (55% male; 45% female). Overall there were 889 deaths (77% female; 33% male, P<0.0001). The in-hospital mortality rate for orthopaedic trauma patients was 2.8% throughout the 7-year study period. 61% of those who died were admitted with proximal femoral fractures. The modal age group with the highest mortality was 81-90 years. Overall, females had a considerably greater mortality rate than males. The mortality rate was lower post-MEWS in males (1.82-1.418%; P=0.214), females (4.871-3.364%; P=0.108) and all patients (3.215-2.294%; P=0.092), but this was not statistically significant.

CONCLUSION

The use of a track and trigger warning system has not led to a statistically significant reduction in mortality in trauma patients. In view of the apparent lack of clinical effectiveness of the MEWS/outreach partnership, the cost effectiveness of this initiative needs to be questioned. Possible reasons for these findings include: failure of the MEWS to be correctly applied, inadequate action once the threshold is triggered, or unsuitability of this tool for this patient population. A better system for identifying and treating elderly, medically unwell trauma patients with co-morbidities needs to be developed.

Outcome of prenatally diagnosed isolated clubfoot

OBJECTIVES

To analyze the aneuploidy risk and treatment outcome of prenatally diagnosed isolated clubfoot, to determine the false-positive rate (FPR) of ultrasound diagnosis and to calculate the risk of diagnostic revision to complex clubfoot.

METHODS

By chart review, 65 patients were retrospectively ascertained to have unilateral or bilateral clubfeet diagnosed prenatally. We calculated the rates of false positives, aneuploidy and diagnostic revision to complex clubfoot, and used an ad hoc scoring system to determine orthopedic outcome. Published rates of aneuploidy were pooled and evaluated.

RESULTS

Prenatally diagnosed isolated clubfoot FPR (defined as 1 - positive predictive value) was 10.5% (95% CI, 5.8-18%) (calculated per foot). After a minimum of 1-year postnatal follow-up, 13% (95% CI, 6-26%) of patients had revised diagnoses of complex clubfoot. No patients had aneuploidy identified by cytogenetic analysis or clinical assessment. Of the 34 patients with 2-year postnatal follow-up, 76.5% were treated with serial casting with or without Botox. All children with isolated clubfoot were walking and had an average outcome score of 'very good' to 'excellent'.

CONCLUSIONS

When counseling women regarding prenatally diagnosed isolated clubfoot, it is important to tell them that approximately 10% of individuals will have a normal foot or positional foot deformity requiring minimal treatment. Conversely, 10-13% of prenatally diagnosed cases of isolated clubfoot will have complex clubfoot postnatally, based on the finding of additional structural or neurodevelopmental abnormalities. Although this study did not identify an increased risk of fetal aneuploidy associated with isolated clubfoot, a review of the literature indicates a risk of 1.7-3.6% with predominance of sex chromosome aneuploidy.

Metabolic programming: Role of nutrition in the immediate postnatal life

Although genes and dietary habits are generally implicated in the aetiology of the prevailing obesity epidemic, the steep increase in the incidence of obesity within a relatively short span of time suggests that other contributing factors may be at play. The role of nutritional experience during the very early periods of life is increasingly being recognized as contributing to growth and metabolic changes in later life. Epidemiological data and studies from animal models have established a strong correlation between an aberrant intrauterine environment and adult-onset disorders in offspring. The nutritional experience in the immediate postnatal life is another independent factor contributing to the development of metabolic diseases in adulthood. Although studies on the small-litter rat model have shown that overnourishment during the suckling period results in adult-onset metabolic disorders, our studies have shown that a change in the quality of calories-specifically, increased carbohydrate intake by newborn rat pups in the immediate postnatal period-results in chronic hyperinsulinaemia and adult-onset obesity. Several functional alterations in islets and in the hypothalamic energy homeostatic mechanism appear to support this phenotype. Remarkably, female rats that underwent the high-carbohydrate dietary modification as neonates spontaneously transmitted the obesity phenotype to their offspring, thus establishing a vicious generational effect. The high-carbohydrate diet-fed rat model has particular relevance in the context of the current human infant feeding practices: reduction in breast feeding and increase in formula feeding for infants, accompanied by early introduction of carbohydrate-enriched baby foods.

A case of Boerhaave's syndrome presenting after a trial of non-invasive ventilation

OBJECTIVE

To highlight the case of a patient with acute respiratory failure, whose diagnosis of Boerhaave's syndrome only became apparent after a trial of non-invasive ventilation.

CLINICAL PRESENTATION AND INTERVENTION

A 68-year-old female presented with a clinical picture of community-acquired pneumonia and exacerbation of asthma that was supported by radiological evidence of a large left-sided pleural effusion. Within 20 h, she deteriorated and progressed to severe type 2 respiratory failure. After initiation of first non-invasive and then invasive ventilation, a tension pneumothorax developed. An emergency decompression of the chest revealed gastric contents in the left hemithorax. A diagnosis of Boerhaave's syndrome was made. Subsequent management included a thoracotomy, defunctioning oesophagectomy, and gastrostomy with ventilatory and inotropic support. However, despite best efforts, the severe systemic inflammatory response resulted in death 3 weeks after initial presentation.

CONCLUSION

It is important to have an open diagnostic mind with a thorough review of investigations and therapy as a patient deteriorates. This case illustrates the importance of considering the remote possibility of oesophageal rupture prior to commencing non-invasive ventilation, especially with regard to chest radiograph features.

Mutations of the E1beta subunit gene (PDHB) in four families with pyruvate dehydrogenase deficiency

Pyruvate dehydrogenase complex (PDC) deficiencies are a major cause of primary lactic acidosis. Most cases result from mutations of the gene for the pyruvate dehydrogenase E1alpha subunit (PDHA1), with fewer cases resulting from mutations in genes for E3, E3-binding protein, E2, and the E1beta subunit (PDHB). We have found four cases of PDHB mutations among 83 analyzed cases of PDC deficiency. In this series, PDHB mutations were found to be about 10% as frequent as PDHA1 mutations. All cases were diagnosed by low PDC activity, with normal E2 and E3 activities. These included a 6.5-year-old male (consanguineous, homozygous R36C); a neonatal female who died soon after birth, (compound heterozygous C306R/D319V), a 26-year-old female (heterozygous I142M/W165S), and a 13month old female (consanguineous, homozygous Y132C) who is a sibling of a previously published case. Their ethnic background is diverse (Caucasian, Arab, and African American descent). All cases had lactic acidosis and developmental delay. Three cases had agenesis of the corpus callosum, seizures, and hypotonia; one died within the first year of life. These clinical findings are similar to those of PDHA1 deficiency, except that ataxia was more frequent in PDHA1 cases and consanguinity was found only in PDHB families. PDC activity in lymphocytes from six parents is normal, who all are heterozygous carriers for the respective mutations. Immunoreactivity of E1beta was markedly reduced in one case and showed a slightly larger form of E1beta in one case. Computer analysis predicts that: R36C affects the interaction of several amino acids resulting in conformational change, C306R affects interaction of the two beta subunits, D319 is in the interface of E1 and E2, I142M affects conformation around a K ion affecting stability of the beta subunit, W165S affects hydrophobic interaction between the beta subunits, and Y132C affects interaction between the beta subunits. All of these residues are conserved in E1beta across species, and Y132 is also conserved in other TPP-requiring enzymes. These observations support the conclusion that these are pathogenic mutations.

The new field of neuroskeletal biology

The fields of neuroscience and bone biology have recently converged following the discovery that bone remodeling is directly regulated by the brain. This work has defined bone remodeling as one of the cardinal physiological functions of the body, subject to homeostatic regulation and integrated with the other major physiological functions by the hypothalamus. Central to this discovery was the definition of the adipocyte-derived hormone leptin as a regulator of both arms of bone remodeling, formation and resorption, through its action on the ventromedial hypothalamus and subsequently via the sympathetic nervous system to osteoblasts. The characterization of the sympathetic nervous system as a regulator of bone remodeling has led to several large clinical studies demonstrating a substantial protective effect of beta-blockers, particularly beta1-blockers, on fracture risk. Studies in model organisms have reinforced the role of the central nervous system in the regulation of bone remodeling in vivo by the identification of several additional genes, namely cocaine and amphetamine regulated transcript (Cart), melanocortin 4 receptor (Mc4R), neuropeptide Y (NPY), Y2 receptor, cannabinoid receptor CB1 (Cnbr1), and the genes of the circadian clock. These genes have several common features, including high levels of expression in the hypothalamus and the ability to regulate other major physiological functions in addition to bone remodeling including energy homeostasis, body weight, and reproduction. We review the major pathways that define the new field of neuroskeletal biology and identify further avenues of inquiry.

Regulation of the pyruvate dehydrogenase complex

The PDC (pyruvate dehydrogenase complex) plays a central role in the maintenance of glucose homoeostasis in mammals. The carbon flux through the PDC is meticulously controlled by elaborate mechanisms involving post-translational (short-term) phosphorylation/dephosphorylation and transcriptional (long-term) controls. The former regulatory mechanism involving multiple phosphorylation sites and tissue-specific distribution of the dedicated kinases and phosphatases is not only dependent on the interactions among the catalytic and regulatory components of the complex but also sensitive to the intramitochondrial redox state and metabolite levels as indicators of the energy status. Furthermore, differential transcriptional controls of the regulatory components of PDC further add to the complexity needed for long-term tuning of PDC activity for the maintenance of glucose homoeostasis during normal and disease states.

An institutional outbreak of leptospirosis in Chennai, South India

The emergence of an outbreak of leptospirosis in a nurses' hostel in Chennai presented a challenge to identify and control the source of the outbreak. Sixty-nine residents and staff members were interviewed to assess exposure factors. Blood samples from the acute and convalescent patients were tested with the Microscopic Agglutination Test using the serovars prevalent in Chennai. Polymerase Chain Reaction (PCR) was conducted on serum and water samples. Based on preliminary investigation, control measures with standard hygienic measures were instituted. The attack rate was 35%. The epidemic curve suggested continuous or intermittent exposure to infection over a five-week period. Twenty residents (three asymptomatic) developed laboratory confirmed Leptospira icterohemorrhagiae. Residents collected water from an underground storage tank that was filled twice weekly from a mobile water tanker with a bucket on a rope, and the tank was usually left open. PCR tests confirmed the presence of leptospires from this water. Other control measures included cleaning the large backyard with its many stray dogs and rats, chlorinating water supplies, boiling drinking water and health education. No further cases occurred twelve days after implementing control measures. Access to clean water, not only for drinking but also for bathing, brushing and washing is essential to prevent water-borne outbreaks.

Identification of a common mutation (Gly194Cys) in both Arab Moslem and Ashkenazi Jewish patients with dihydrolipoamide dehydrogenase (E3) deficiency: possible beneficial effect of vitamin therapy

Dihydrolipoamide dehydrogenase (E3) deficiency with a clinical phenotype and genotype (Gly194Cys homozygous) previously identified only in Ashkenazi Jewish patients, was diagnosed in two Palestinian Arab siblings and two unrelated Ashkenazi Jewish patients. While three of the four patients died in childhood without specific treatment, the surviving patient at age 18 years may have benefited from long-term daily supplementation with a cocktail of riboflavin, biotin, coenzyme Q and carnitine.

Regulation of mammalian pyruvate dehydrogenase complex by phosphorylation: complexity of multiple phosphorylation sites and kinases

This review summarizes the recent developments on the regulation of human pyruvate dehydrogenase complex (PDC) by site-specific phosphorylation by four kinases. Mutagenic analysis of the three phosphorylation sites of human pyruvate dehydrogenase (E1) showed the site-independent mechanism of phosphorylation as well as site-independent dephosphorylation of the three phosphorylation sites and the importance of each phosphorylation site for the inactivation of E1. Both the negative charge and size of the group introduced at site 1 were involved in human E1 inactivation. Mechanism of inactivation of E1 was suggested to be site-specific. Phosphorylation of site 1 affected E1 interaction with the lipoyl domain of dihydrolipoamide acetyltransferase, whereas phosphorylation site 3 appeared to be closer to the thiamine pyrophosphate (TPP)-binding region affecting coenzyme interaction with human E1. Four isoenzymes of pyruvate dehydrogenase kinase (PDK) showed different specificity for the three phosphorylation sites of E1. All four PDKs phosphorylated sites 1 and 2 in PDC with different rates, and only PDK1 phosphorylated site 3. PDK2 was maximally stimulated by the reduction/acetylation of the lipoyl groups of E2. Presence of the multiple phosphorylation sites and isoenzymes of PDK is important for the tissue-specific regulation of PDC under different physiological conditions.

Differential effects of two mutations at arginine-234 in the alpha subunit of human pyruvate dehydrogenase

The most common mutation in the alpha subunit of the pyruvate dehydrogenase (E1) component of the human pyruvate dehydrogenase complex (PDC) is arginine-234 to glycine and glutamine in 12 and 3 patients, respectively. Interestingly, these two mutations at the same amino acid position cause E1 (and hence PDC) deficiency by apparently different mechanisms. Recombinant human R234Q E1 had similar V(max) (25.7 +/- 4.4 units/mg E1) and apparent K(m) (101 +/- 4 nM) values for TPP as recombinant wild-type human E1, while R234G E1 had no significant change in V(max) (33.6 +/- 4.7 units/mg E1) but had a 7-fold increase in its apparent K(m) value for TPP (497 +/- 25 nM). Both of the R234 mutant proteins had similar apparent K(m) values for pyruvate. Both R234Q and R234G mutant proteins displayed similar phosphorylation rates of sites 1 and 2 by pyruvate dehydrogenase kinase 2 (PDK2) and site 3 by PDK1 compared to wild-type E1. Phosphorylated R234Q E1, R234G E1, and wild-type E1 also had similar dephosphorylation rates of sites 1 and 2 by phosphopyruvate dehydrogenase phosphatase 1. The rate of dephosphorylation of site 3 was about 50% for R234Q E1 and without a significant change for R234G E1 compared to the wild type. The data indicate that the patients with the R234G E1 mutation are symptomatic due to a decreased ability of this mutant protein to bind TPP, whereas the patients with the R234Q E1 mutation are symptomatic due to a decreased rate of dephosphorylation of site 3, hence keeping the enzyme in a phosphorylated/inactivated form.

Inactivation of the murine pyruvate dehydrogenase (Pdha1) gene and its effect on early embryonic development

A deficiency of pyruvate dehydrogenase complex (PDC) in humans results in lactic acidosis and neurological dysfunction that frequently results in death during infancy. Using gene targeting technology, a silent mutation was introduced into the murine X-linked Pdha1 gene that encodes the alpha subunit of the pyruvate dehydrogenase or E1 component of the complex. Two loxP sequences were introduced into intronic sequences flanking exon 8 to generate the Pdha1(flox8) allele. In vitro studies in embryonic stem cells demonstrated that deletion of exon 8 ablated PDC activity. Homozygous Pdha1(flox8) females were bred with male mice carrying a wild-type Pdha1 allele and a transgene that ubiquitously expresses the Cre recombinase to produce progeny with a deletion in exon 8, Pdha1(Deltaex8). The majority of progeny were found to be mosaic with the presence of both the flox and deleted alleles, and there were no apparent phenotypic effects associated with the null allele. The mosaic mice were interbred to increase the degree of mosaicism for the Pdha1(Deltaex8) allele in the subsequent generation, resulting in a significantly smaller litter size (54% reduction). Embryos carrying predominantly the Pdha1(Deltaex8) allele were found to be globally delayed in development by 9.5 days postcoitus, with resorption occurring over the following several days. These findings demonstrate an essential role for oxidative metabolism of glucose during the early postimplantation period of prenatal development.

Site specificity of four pyruvate dehydrogenase kinase isoenzymes toward the three phosphorylation sites of human pyruvate dehydrogenase

Activity of the mammalian pyruvate dehydrogenase complex is regulated by phosphorylation-dephosphorylation of three specific serine residues (site 1, Ser-264; site 2, Ser-271; site 3, Ser-203) of the alpha subunit of the pyruvate dehydrogenase (E1) component. Phosphorylation is carried out by four pyruvate dehydrogenase kinase (PDK) isoenzymes. Specificity of the four mammalian PDKs toward the three phosphorylation sites of E1 was investigated using the recombinant E1 mutant proteins with only one functional phosphorylation site present. All four PDKs phosphorylated site 1 and site 2, however, with different rates in phosphate buffer (for site 1, PDK2 > PDK4 approximately PDK1 > PDK3; for site 2, PDK3 > PDK4 > PDK2 > PDK1). Site 3 was phosphorylated by PDK1 only. The maximum activation by dihydrolipoamide acetyltransferase was demonstrated by PDK3. In the free form, all PDKs phosphorylated site 1, and PDK4 had the highest activity toward site 2. The activity of the four PDKs was stimulated to a different extent by the reduction and acetylation state of the lipoyl moieties of dihydrolipoamide acetyltransferase with the maximum stimulation of PDK2. Substitution of the site 1 serine with glutamate, which mimics phosphorylation-dependent inactivation of E1, did not affect phosphorylation of site 2 by four PDKs and of site 3 by PDK1. Site specificity for phosphorylation of four PDKs with unique tissue distribution could contribute to the tissue-specific regulation of the pyruvate dehydrogenase complex in normal and pathophysiological states.

Use of a cDNA array for the identification of genes induced in islets of suckling rats by a high-carbohydrate nutritional intervention

Four-day-old rat pups that are raised artificially on a high-carbohydrate (HC) milk formula immediately develop hyperinsulinemia, which persists into adulthood without any further nutritional stimulus. cDNA array analysis was used to identify large-scale changes in gene expression patterns in islets from 12- and 100-day-old HC rats in response to the HC dietary modification during the suckling period. It was observed that the expression of several genes that belong to clusters involved in beta-cell development and/or beta-cell function was significantly upregulated in islets from 12- and 100-day-old HC rats. It is inferred that in addition to predicted changes in gene expression, for example preproinsulin gene, global changes in gene expression contribute to the hyperinsulinemic state in the HC rat.

Programming into adulthood of islet adaptations induced by early nutritional intervention in the rat

To investigate the influence of a high carbohydrate (HC) intake during the suckling period on pancreatic function in adult life, neonatal rats were artificially reared on a HC milk formula during the preweaning period and then weaned onto lab chow. In the adult HC rat, hyperinsulinemia is sustained by a variety of biochemical and molecular adaptations induced in the HC islets during the suckling period. The adult HC islets showed a distinct left shift in the glucose-stimulated insulin-secretory pattern. HC islets were also able to secrete moderate levels of insulin in the absence of glucose and in the presence of Ca(2+) channel inhibitors. In addition, the mRNA levels of preproinsulin, somatostatin transcription factor-1, upstream stimulatory factor-1, stress-activated protein kinase-2, phosphatidylinositol kinase, and GLUT-2 genes were significantly increased in HC islets. These results show that consumption of a HC formula during the suckling period programs pancreatic islet function in adult rats, resulting in the maintenance of hyperinsulinemia in the postweaning period and eventually leading to the development of obesity in adult life.

Human dihydrolipoamide dehydrogenase gene transcription is mediated by cAMP-response element-like site and TACGAC direct repeat

Dihydrolipoamide dehydrogenase is a common component of four multienzyme complexes which are involved in oxidation of carbohydrates, lipids and amino acids. To better understand the regulation of human DLD gene expression, we have analyzed the proximal promoter region of this gene. DNase I footprinting analysis of the promoter region (-322 to +47 bp) revealed four major protein-binding domains (termed P1-P4). Nested deletions and site-specific mutations of approximately 100 bp proximal promoter region identified two elements, TACGAC direct repeat sequence and cAMP-response element (CRE)-like site, which are localized in the P2 and P1 domains, respectively, and mediate basal transcription of the DLD gene. Electrophoretic mobility supershift assays showed that the CRE-like site is associated with CRE binding protein. Interestingly, when DLD promoter constructs (-1.8 kb to +47 bp and -78 to +47 bp) fused with the chloramphenicol acetyltransferase (CAT) reporter gene were transiently transfected into human HepG2 cells either in the presence or absence of 0.5 mM 8-Br-cAMP, the levels of CAT expression remained unaffected. In addition, endogenous DLD mRNA levels in HepG2 cells also remained unaffected by treatment with 0.5 mM 8-Br-cAMP. These results indicate that the CRE binding protein is essential for basal transcription of the human DLD promoter, but does not confer cAMP-dependent gene regulation.

Protection by thiols of the mitochondrial complexes from 4-hydroxy-2-nonenal

In the present study, the effects of 4-hydroxy-2-nonenal (HNE) on highly purified pyruvate dehydrogenase complex (PDC) and its catalytic components in vitro and on PDC, alpha-ketoglutarate dehydrogenase complex (KGDC), and the branched-chain alpha-keto acid dehydrogenase complex (BCKDC) activities in cultured human HepG2 cells were investigated. Among the PDC components, the activity of the dihydrolipoamide acetyltransferase-E3-binding protein subcomplex (E2-E3BP) only was decreased by HNE. Dihydrolipoamide dehydrogenase (E3) protected the E2-E3BP subcomplex from HNE inactivation in the absence of the substrates. In the presence of E3 and NADH, when lipoyl groups were reduced, higher inactivation of the E2-E3BP subcomplex by HNE was observed. Purified PDC was protected from HNE-induced inactivation by several thiol compounds including lipoic acid plus [LA-plus; 2-(N,N-dimethylamine)ethylamidolipoate(.)HCl]. Treatment of cultured HepG2 cells with HNE resulted in a significant reduction of PDC and KGDC activities, whereas BCKDC activity decreased to a lesser extent. Lipoyl compounds afforded protection from HNE-induced inhibition of PDC. This protection was higher in the presence of cysteine and reduced glutathione. Cysteine was able to restore PDC activity to some extent after HNE treatment. These findings show that thiols, including lipoic acid, provide protection against HNE-induced inactivation of lipoyl-containing complexes in the mitochondria.

Probing the mechanism of inactivation of human pyruvate dehydrogenase by phosphorylation of three sites

Activity of the mammalian pyruvate dehydrogenase complex (PDC) is regulated by phosphorylation-dephosphorylation of three serine residues (designated site 1, Ser-264; site 2, Ser-271; site 3, Ser-203) in the alpha subunit of the pyruvate dehydrogenase (E1) component. Substitutions of the phosphorylation sites were generated by site-directed mutagenesis. Glutamate (S1E) and aspartate (S1D) substitutions at site 1 resulted in the complete loss of PDC activity; however, these mutants were variably active in the decarboxylation and 2,6-dichlorophenolindophenol assays. S1Q had only 3% of wild-type PDC activity. The apparent K(m) values for pyruvate increased for the mutants of site 1 when determined in the 2,6-dichlorophenolindophenol assay. The substitutions at sites 2 and 3 caused only moderate reductions in activity in the three assays. S3E had a 27-fold increase in the apparent K(m) for thiamine pyrophosphate and 8-fold increase in the K(i) for pyrophosphate. Site 3 was almost completely protected from phosphorylation by thiamine pyrophosphate. The results show that the size rather than negative charge of the substituted amino acid residue affects the active site of E1 and that modification of each of the three serine residues affect the active site in a site-specific manner for its ability to bind the cofactor and substrates.

Mitochondrial-encoded gene regulation in rat pancreatic islets

Mitochondrial adenosine triphosphate (ATP) generation plays a major role in insulin secretion in pancreatic islet beta cells. The relationship between age and nutritional status of the islet and mitochondrial gene messenger RNA (mRNA) expression was investigated. Three animal groups were studied: infant (12-day-old) rats fed either mother's milk or a high carbohydrate (HC) diet; young (2 to 4-month-old) rats; and old (12 to 14-month-old) rats. The expression of mitochondrial cytochrome oxidase (CYO) (subunits I, II, and III), beta-nicotinamide adenine dinucleotide, reduced form dehydrogenase subunit 4 (NADH-DH4), and ATP synthase (subunit 6) (ATP-SYN6) mRNAs was characterized by semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR). The mitochondrial gene mRNAs were identified in each of the groups of rat islets and in RINm5F cells. CYO-II mRNA expression in young and old rat pancreatic islets was 12.7- and 8.2-fold higher, respectively, compared with the level in infant rat islets. The expression of NADH-DH4 and ATP-SYN6 mRNAs was 47% and 40% lower, respectively, in young rat islets compared with the level in infant rat islets. CYO-I, CYO-III, and cytoplasmic glyceraldehyde-3-phosphate dehydrogenase (GPDH) mRNA expression did not differ between experimental groups. Artificial rearing of infant rat pups on a HC diet for 8 days lead to a 3.3-fold increase in islet CYO-II mRNA expression compared with mother-fed pups. However, glucose (11 mmol/L) stimulation of cultured isolated islets from young and old rats for 4 days failed to affect the expression level of mitochondrial gene mRNAs. Thus, aging affected the differential expression of CYO-II, NADH-DH4, and ATP-SYN6 mRNAs in rat islets. CYO-II mRNA expression was modulated only in infant rat islets after in vivo administration of carbohydrate.

A long-term high-carbohydrate diet causes an altered ontogeny of pancreatic islets of Langerhans in the neonatal rat

Neonatal rats fed a high-carbohydrate (HC) formula by gastrostomy are hyperinsulinemic but normoglycemic. We determined whether HC formula altered pancreatic islet cell ontogeny. Rats were reared from d 4 on an HC formula or a high-fat formula, or were allowed to suckle naturally, and the pancreata were examined histologically from animals < or =24 d of age. The mean area of individual islets was reduced, but islet number was increased in HC rats compared with mother-fed or high fat-fed animals, which were similar. Islets from HC animals were relatively deficient in alpha cells and had a greater incidence of islet cells with fragmented DNA, indicative of apoptosis. Ductal epithelium, a source of new islets by neogenesis, had a greater incidence of cells staining immunopositive for proliferating cell nuclear antigen, a marker of cell replication, and a lower incidence of apoptosis. The islet cell mitogen and survival factor, IGF-II, had a reduced mRNA expression in whole pancreas from HC animals. The relative area of islet cells demonstrating IGF-II immunoreactivity was reduced in HC-fed rats versus controls, although a greater percentage of ductal epithelial cells were immunopositive. HC formula alters islet cell ontogeny by affecting islet size and number, which may be linked to an altered IGF-II expression.