Acetyl-CoA carboxylase 1 is a suppressor of the adipocyte thermogenic program.

Disruption of adipocyte de novo lipogenesis (DNL) by deletion of fatty acid synthase (FASN) in mice induces browning in inguinal white adipose tissue (iWAT). However, adipocyte FASN knockout (KO) increases acetyl-coenzyme A (CoA) and malonyl-CoA in addition to depletion of palmitate. We explore which of these metabolite changes triggers adipose browning by generating eight adipose-selective KO mouse models with loss of ATP-citrate lyase (ACLY), acetyl-CoA carboxylase 1 (ACC1), ACC2, malonyl-CoA decarboxylase (MCD) or FASN, or dual KOs ACLY/FASN, ACC1/FASN, and ACC2/FASN. Preventing elevation of acetyl-CoA and malonyl-CoA by depletion of adipocyte ACLY or ACC1 in combination with FASN KO does not block the browning of iWAT. Conversely, elevating malonyl-CoA levels in MCD KO mice does not induce browning. Strikingly, adipose ACC1 KO induces a strong iWAT thermogenic response similar to FASN KO while also blocking malonyl-CoA and palmitate synthesis. Thus, ACC1 and FASN are strong suppressors of adipocyte thermogenesis through promoting lipid synthesis rather than modulating the DNL intermediates acetyl-CoA or malonyl-CoA.

De novo lipogenesis fuels adipocyte autophagosome and lysosome membrane dynamics.

Adipocytes robustly synthesize fatty acids (FA) from carbohydrate through the de novo lipogenesis (DNL) pathway, yet surprisingly DNL contributes little to their abundant triglyceride stored in lipid droplets. This conundrum raises the hypothesis that adipocyte DNL instead enables membrane expansions to occur in processes like autophagy, which requires an abundant supply of phospholipids. We report here that adipocyte Fasn deficiency in vitro and in vivo markedly impairs autophagy, evident by autophagosome accumulation and severely compromised degradation of the autophagic substrate p62. Our data indicate the impairment occurs at the level of autophagosome-lysosome fusion, and indeed, loss of Fasn decreases certain membrane phosphoinositides necessary for autophagosome and lysosome maturation and fusion. Autophagy dependence on FA produced by Fasn is not fully alleviated by exogenous FA in cultured adipocytes, and interestingly, imaging studies reveal that Fasn colocalizes with nascent autophagosomes. Together, our studies identify DNL as a critical source of FAs to fuel autophagosome and lysosome maturation and fusion in adipocytes.

First cases of KPC-type carbapenemase-producing bacteria in patients in New Zealand hospitals.

The emergence and global spread of Klebsiella pneumoniae carbapenemases (KPCs) is a significant public health problem. Between October 2010 and July 2013, KPC-producing K. pneumoniae were isolated from four patients in New Zealand hospitals. These cases are the first known isolations of KPC-producing organisms in New Zealand. All four patients were transferred from, or had recently been in, hospitals in countries where KPC-producing organisms are prevalent (China, India, Greece and Italy). The blaKPC-2 gene was identified in the isolates from three patients and blaKPC-3 was identified in the isolate from the remaining patient. The isolates belonged to different multilocus sequence type clonal complexes, usually those prevalent in the country in which the patient had been previously hospitalised. Currently in New Zealand, the common factor associated with having a KPC-producing organism is prior hospitalisation in another country where these organisms are prevalent.

Incidence of nontuberculous mycobacterial disease in New Zealand, 2004.

AIM: To record the incidence and clinical significance of nontuberculous mycobacteria (NTM) infection in New Zealand (NZ) in 2004. METHOD: In 2004 each of NZ's mycobacterium reference laboratories collected data on NTM isolates. The clinical significance of isolates was decided by contacting the requesting clinician. American Thoracic Society criteria were used to assign clinical significance to respiratory isolates. RESULTS: 368 patients had NTM isolated from various sites. 21% (78/368) were clinically significant [15% (47/316) of respiratory isolates, 100% (17/17) lymph node and 89% (8/9) of soft tissue isolates]. Of the significant isolates, Mycobacterium avium intracellulare complex (MAIC) was the most common, accounting for 83%, 88%, and 44% of respiratory, lymph node, and soft tissue infections respectively. Rapidly growing mycobacteria (RGM) were the second most common cause of significant infection. Of 47 patients with significant respiratory isolates 79% were female and 83% had underlying lung disease. The incidence of disease caused by NTM in NZ in 2004 was 1.92/100,000 population. The specific incidence of pulmonary, lymph node and soft tissue infections was 1.17, 0.39, and 0.24 per 100,000 population respectively. CONCLUSION: The incidence of NTM respiratory disease in NZ during 2004 is approximately twice that recorded for Australia in 2000 (0.56/100,000). MAIC is the most common pathogen, followed by RGM. Both organisms most commonly cause respiratory infections in elderly female patients with underlying lung disease.