Gene expression and characterization of clonally derived murine embryonic brown and brite adipocytes.

White adipocytes store energy, while brown and brite adipocytes release heat via nonshivering thermogenesis. In this study, we characterized two murine embryonic clonal preadipocyte lines, EB5 and EB7, each displaying unique gene marker expression profiles. EB5 cells differentiate into brown adipocytes, whereas EB7 cells into brite (also known as beige) adipocytes. To draw a comprehensive comparison, we contrasted the gene expression patterns, adipogenic capacity, as well as carbohydrate and lipid metabolism of these cells to that of F442A, a well-known white preadipocyte and adipocyte model. We found that commitment to differentiation in both EB5 and EB7 cells can be induced by 3-Isobutyl-1-methylxanthine/dexamethasone (Mix/Dex) and staurosporine/dexamethasone (St/Dex) treatments. Additionally, the administration of rosiglitazone significantly enhances the brown and brite adipocyte phenotypes. Our data also reveal the involvement of a series of genes in the transcriptional cascade guiding adipogenesis, pinpointing GSK3ß as a critical regulator for both EB5 and EB7 adipogenesis. In a developmental context, we observe that, akin to brown fat progenitors, brite fat progenitors make their appearance in murine development by 11-12 days of gestation or potentially earlier. This result contributes to our understanding of adipocyte lineage specification during embryonic development. In conclusion, EB5 and EB7 cell lines are valuable for research into adipocyte biology, providing insights into the differentiation and development of brown and beige adipocytes. Furthermore, they could be useful for the characterization of drugs targeting energy balance for the treatment of obesity and metabolic diseases.

FAM129B is a cooperative protein that regulates adipogenesis.

FAM129B is one of Niban-like proteins described in neoplastic cells and implicated in melanoma cell invasion, but no reports have been published on FAM129B and cell differentiation. We show that FAM129B is early and transiently expressed and crucial for 3T3-F442A adipogenesis. Fam129b is expressed downstream of the early genes Cebpb, Klf4, Klf5 and Srebf1a, but upstream of Pparg2 since knockdown of Fam129b blocked Pparg2 expression and adipose differentiation. Glycogen synthase kinase 3 beta activity, a crucial kinase for adipogenesis, and the ERK1/2 are involved in FAM129B phosphorylation as part of the adipogenic program. Phosphorylated FAM129B is crucial for Pparg2 expression and the lipogenic gene expression downstream of Pparg2, and hence for adipogenesis. Fam129b knockdown reduced adipocyte cluster formation and size, regulating commitment and clonal amplification. In vivo, BAT, inguinal and epidydimal fat expressed Fam129b, suggesting a role in adipose tissue development. We conclude that FAM129B is a cooperative protein that regulates differentiation during the early stages of adipogenesis.

A cellular perspective of adipogenesis transcriptional regulation.

Adipose cells store lipids in the cytoplasm and signal systemically through secretion of adipokines and other molecules that regulate body energy metabolism. Differentiation of fat cells and its regulation has been the focus of extensive research since the early 1970s. In this review, we had attempted to examine the research bearing on the control of adipose cell differentiation, some of it dating back to the early days when Howard Green and his group described the preadipocyte cell lines 3T3-L1 and 3T3-F442A during 1974-1975. We also concentrated our attention on research published during the last few years, emphasizing data described on transcription factors that regulate adipose differentiation, outside of those that were reported earlier as part of the canonical adipogenic transcriptional cascade, which has been the subject of ample reviews by several groups of researchers. We focused on the studies carried out with the two preadipocyte cell culture models, the 3T3-L1 and 3T3-F442A cells that have provided essential data on adipose biology.

Utility of venous blood gases in severe sepsis and septic shock.

Acid-base status is frequently assessed in severe sepsis and septic shock. Venous blood gas sampling is proposed as a less-invasive modality but lacks evidence within this population. The objective of this study was to evaluate the correlation and agreement between arterial blood gas (ABG), peripheral venous blood gas (pVBG), and central venous blood gas (cVBG) in severe sepsis and septic shock. We conducted a prospective, observational cohort study in subjects admitted to the medical intensive care unit. Simultaneous blood gas samples, including ABG, pVBG, and cVBG, were analyzed for correlation and agreement. Severity of illness scores revealed a mean (±SD) Sequential Organ Failure Assessment score of 7.9 ± 3.3, Simplified Acute Physiology II score of 49.3 ± 16.5, and a mortality rate of 11.9% in the intensive care unit and 16.4% in the hospital. We found a strong intraclass correlation (>0.85) for pH, partial pressure of carbon dioxide (pCO2), bicarbonate, and base excess for ABG/pVBG, ABG/cVBG, and pVBG/cVBG comparisons. Agreement by the Bland-Altman method was found for pH (bias ± SD, 0.03 ± 0.04, 0.03 ± 0.02, and 0.00 ± 0.03) but not for pCO2, partial pressure of oxygen, bicarbonate, base excess, and oxyhemoglobin saturation. In conclusion, adequate correlation and agreement between ABG/pVBG, ABG/cVBG, and pVBG/cVBG comparisons was found only for pH. The current level of evidence does not support the use of venous blood gas sampling in this setting.

Critically ill patients and gut motility: Are we addressing it?

Gastrointestinal (GI) dysmotility is a common problem in the critically ill population. It can be a reflection and an early sign of patient deterioration or it can be an independent cause of morbidity and mortality. GI dysmotility can be divided for clinical purposes on upper GI dysmotility and lower GI dysmotility. Upper GI dysmotility manifests by nausea, feeding intolerance and vomiting; its implications include aspiration into the airway of abdominal contents and underfeeding. Several strategies to prevent and treat this condition can be tried and they include prokinetics and post-pyloric feeds. It is important to note that upper GI dysmotility should be treated only when there are clinical signs of intolerance (nausea, vomiting) and not based on measurement of gastric residual volumes. Lower GI dysmotility manifests throughout the spectrum of ileus and diarrhea. Ileus can present in the small bowel and the large bowel as well. In both scenarios the initial treatment is correction of electrolyte abnormalities, avoiding drugs that can decrease motility and patient mobilization. When this fails, in the case of small bowel ileus, lactulose and polyethylene glycol solutions can be useful. In the case of colonic pseudo obstruction, neostigmine, endoscopic decompression and cecostomy can be tried when the situation reaches the risk of rupture. Diarrhea is also a common manifestation of GI dysmotility and the most important step is to differentiate between infectious sources and non-infectious sources.

Hypoventilation in neuromuscular disease.

Hypoventilation in neuromuscular disease is attributed to both respiratory muscle weakness and reduced chemoreceptor sensitivity essential in ventilatory drive. Acute or chronic respiratory failure is seen in a spectrum of neuromuscular disease; whereas some are treatable others are progressive and devastating. Sleep is associated with a reduction in ventilation and hence worsening hypoventilation. Problems with sleep may be an early indicator of further muscle weakness and should prompt the clinician for further investigation, though usefulness of pulmonary function testing, arterial blood gas analysis, and other measures may not be universally predictive. The timing of respiratory failure is variable, but knowledge of the clinical aspects, pathogenesis, and treatment of respiratory failure and hypoventilation may be helpful in evaluating the patient with neuromuscular disease. For those with progressive and terminal disease, additional factors such as end of life care, especially ventilation and cough, may be useful for the patient, caregivers, and treating medical personnel.