Cadmium chloride inhibits lactate gluconeogenesis in isolated human renal proximal tubules: a cellular metabolomic approach with <Superscript>13</Superscript>C-NMR

As part of a study on cadmium nephrotoxicity, we studied the effect of cadmium chloride (CdCl₂) in isolated human renal proximal tubules metabolizing the physiological substrate lactate. Dose–effect experiments showed that 10–500 μM CdCl₂ reduced lactate removal, glucose production and the cellular levels of ATP, coenzyme A, acetyl-coenzyme A and of reduced glutathione in a dose-dependent manner. After incubation with 5 mM l-[1-¹³C]-, or l-[2-¹³C]-, or l-[3-¹³C] lactate or 5 mM l-lactate plus 25 mM NaH¹³CO₃ as substrates, substrate utilization and product formation were measured by both enzymatic and carbon 13 NMR methods. Combination of enzymatic and NMR measurements with a mathematical model of lactate metabolism previously validated showed that 100 μM CdCl₂ caused an inhibition of flux through lactate dehydrogenase and alanine aminotransferase and through the entire gluconeogenic pathway; fluxes were diminished by 19% (lactate dehydrogenase), 28% (alanine aminotransferase), 28% (pyruvate carboxylase), 42% (phosphoenolpyruvate carboxykinase), and 52% (glucose-6-phosphatase). Such effects occurred without altering the oxidation of the lactate carbons or fluxes through enzymes of the tricarboxylic acid cycle despite a large fall of the cellular ATP level, a marker of the energy status and of the viability of the renal cells. These results that were observed at clinically relevant tissue concentrations of cadmium provide a biochemical basis for a better understanding of the cellular mechanism of cadmium-induced renal proximal tubulopathy in humans chronically exposed to cadmium.     

Carbon Monoxide–Sensitive Apoptotic Death of Erythrocytes

Carbon monoxide (CO) intoxication severely interferes with the oxygen‐transporting function of haemoglobin. Beyond that, CO participates in the regulation of apoptosis. CO could be generated from CO‐releasing molecules (CORM), such as the tricarbonyl‐dichlororuthenium (II) dimer (CORM‐2), which is presently considered for the treatment of vascular dysfunction, inflammation, tissue ischaemia and organ rejection. CORM‐2 is at least partially effective by modifying gene expression and mitochondrial potential. Erythrocytes lack nuclei and mitochondria but may undergo suicidal cell death or eryptosis, characterized by cell shrinkage and phospholipid scrambling of the cell membrane. Eryptosis is triggered by the increase in cytosolic Ca²⁺ activity ([ Ca²⁺ ]_i). The present study explored whether CORM‐2 influences eryptosis. To this end, [ Ca²⁺ ]_i was estimated from Fluo‐3‐fluorescence, cell volume from forward scatter, phospholipid scrambling from annexin‐V‐binding and haemolysis from haemoglobin release. CO‐binding haemoglobin (COHb) was estimated utilizing a blood gas analyser. As a result, exposure of erythrocytes for 24 hr to CORM‐2 (≥5 μM) significantly increased COHb, [ Ca²⁺ ]_i, forward scatter, annexin‐V‐binding and haemolysis. Annexin‐V‐binding was significantly blunted by 100% oxygen and was virtually abolished in the nominal absence of Ca²⁺ . In conclusion, CORM‐2 stimulates cell membrane scrambling of erythrocytes, an effect largely due to Ca²⁺ entry and partially reversed by O₂ .     

A cohort study of results following elective colonic and rectal resection within an enhanced recovery programme

Objective  The use of laparoscopic surgery coupled with an enhanced recovery programme (ERP) has resulted in hospital stays of 4 or less days for colonic and 6 days following rectal resection, in previously reported small selected groups of patients. This report analyses an unselected cohort to determine if such benefits are reproducible.
Method   Consecutive patients undergoing elective colonic or rectal surgery at a single centre between January 2002 and January 2006 were followed. All were included in the ERP and underwent either laparoscopic or open surgery.
Results   The study group comprised 241 patients (mean age of 67 ± standard deviation 14 years and 49% male sex distribution) who underwent elective colorectal resection within the context of an ERP. One hundred and fifty-one (62.7%) patients had malignant disease. Overall, 191 (79.3%) patients underwent a laparoscopic procedure and the remaining underwent an open operation. Postoperative stay was shorter in patients undergoing laparoscopic vs open, colonic surgery (4 days vs 6 days, P  = 0.002). A nonsignificant trend towards reduced postoperative stay was observed for patients undergoing laparoscopic vs open, rectal surgery (6 days vs 9 days, P  = 0.088). Patients undergoing laparoscopic colectomy demonstrated significantly lower 30-day mortality rates than those undergoing traditional colectomy (3/131 vs 3/39, P  = 0.049).
Conclusion  Laparoscopic colonic surgery in the context of an ERP offers reduced hospital stay and may confer a survival advantage over traditional techniques. These results confirm that previously reported benefits of laparoscopic surgery are reproducible within an unselected population.     

Spontaneous coronary artery dissection

Spontaneous coronary artery dissection (SCAD) is a relatively rare but important cause of acute coronary syndrome. The diagnosis is often made at autopsy. Risk factors include the peripartum period, oral contraceptive use, and atherosclerotic disease. SCAD must be considered every time a healthy young patient presents with an onset of acute myocardial ischemic syndrome. A timely diagnosis and intervention are mandatory as SCAD can cause sudden death. We describe two cases of SCAD, both treated successfully with emergency coronary artery bypass grafting using left internal mammary and radial arteries in the first case and the left internal mammary artery only for the second case.     

Human leukocyte antigen (HLA) class II association with rheumatic heart disease in Pakistan

BACKGROUND AND AIM of the study: Rheumatic heart disease (RHD) is widespread in Pakistan. Specific alleles of the human leukocyte antigen (HLA) system are associated with RHD in various world populations. The study aim was to investigate the involvement of HLA class II alleles in genetic susceptibility to RHD in patients with relatively homogeneous clinical manifestations, in Pakistan. METHODS: Blood samples were collected from 114 unrelated patients (94 females, 20 males) with rheumatic mitral valve disease, predominantly mitral stenosis, as assessed by echocardiography. The control group comprised 109 unrelated, ethnically matched, healthy individuals (60 females, 49 males) with normal echocardiograms. Genomic DNA was extracted from venous blood using a standard phenol/chloroform extraction procedure. HLA-DRB, -DQA1, and -DQB1 alleles were typed using polymerase chain reaction with sequence-specific primers. HLA allele and haplotypes frequencies were then calculated. RESULTS: A significantly higher frequency of DRB1*07 was observed in patients as compared to controls (one-way parametric analysis of variance, F = 4.84, p = 0.028; OR = 1.76, p = 0.039). No alleles for the HLA-DQA1 or -DQB1 loci were associated with the disease. HLA-DRB1*07-DQA1*0501-DQB1*02, the only haplotype that differed significantly between patients and controls (one-way parametric Anova, F = 4.866, p = 0.028; OR = 7.33, p = 0.06), did not exhibit significant linkage disequilibrium. CONCLUSION: These results show that HLA-DRB1*07, associated with RHD in various world populations, is also associated with RHD in the Pakistani population. The validation of HLA associations with RHD, which is observed in different world populations, may lead to the development of a cost-effective strategy in the primary prevention of this disease.