Perspective: a stirring role for metabolism in cells

Based on recent findings indicating that metabolism might be governed by a limit on the rate at which cells can dissipate Gibbs energy, in this Perspective, we propose a new mechanism of how metabolic activity could globally regulate biomolecular processes in a cell. Specifically, we postulate that Gibbs energy released in metabolic reactions is used to perform work, allowing enzymes to self‐propel or to break free from supramolecular structures. This catalysis‐induced enzyme movement will result in increased intracellular motion, which in turn can compromise biomolecular functions. Once the increased intracellular motion has a detrimental effect on regulatory mechanisms, this will establish a feedback mechanism on metabolic activity, and result in the observed thermodynamic limit. While this proposed explanation for the identified upper rate limit on cellular Gibbs energy dissipation rate awaits experimental validation, it offers an intriguing perspective of how metabolic activity can globally affect biomolecular functions and will hopefully spark new research.     

Seasonal physiology of the wild raccoon dog (Nyctereutes procyonoides)

The raccoon dog (Nyctereutes procyonoides) is a canid omnivore with autumnal fattening and winter sleep. Farmraised raccoon dogs have elevated plasma leptin and growth hormone levels in the winter and depressed plasma cortisol and insulin concentrations during wintertime food deprivation. However, these parameters were not previously tested in the wild population. In the present study 37 wild raccoon dogs were sampled at different seasons and diverse biochemical variables were determined. The results mostly confirmed previous observations on farmraised raccoon dogs. The liver glycogen stores increased during the autumnal fattening period but were low in the winter. The liver glycogen phosphorylase activity decreased but lipase activity increased in the winter indicating the use of fat as the principal metabolic fuel. The plasma insulin concentrations were low in the winter allowing the release of fatty acids from adipose tissue. Low wintertime cortisol and thyroid hormone levels could contribute to protein sparing. Unlike on farms, wild raccoon dogs did not show seasonal fluctuations in their plasma ghrelin or growth hormone levels. The observed physiological phenomena emphasise the adaptation of the species to long periods of food scarcity in the winter.     

Oral health and treatment needs of the long-term hospitalised elderly

Objectives: To determine the oral health and treatment needs of the long‐term hospitalised elderly. Setting: The Laakso long‐term hospital, Helsinki, Finland. Design: A cross‐sectional study with clinical oral examinations. Subjects: All long‐term patients (n = 260) aged 60 and older. Main outcome measures: Edentulousness, presence and hygiene of dentures, mucosal findings, number of teeth, functioning teeth and tooth remnants, level of dental hygiene, and need for operative treatment. Results: Subjects’ mean age was 83.3 years (SD = 8.1); 42% were edentulous, 45% of women and 33% of men (p = 0.12). With no gender difference, 41% had removable dentures, but one in four were considered to be in need of repair or replacement. Denture hygiene was good in 19%, moderate in 44%, and poor in 37%, and for men worse than for women (p = 0.02). Stomatitis was found in 25%, and angular cheilitis in 28% of the denture wearers. The dentate subjects had on average 12.4 (SD = 8.6) teeth with a clear difference by age (p = 0.03), but no difference by gender. Dental hygiene was considered poor. Of the dentate subjects, 37% were in need of restorations, 51% of periodontal therapy and 42% of extractions. Conclusions: Oral cleanliness should be improved with regards to dentures and teeth. More attention should be focused on dental care of the long‐term hospitalised elderly.     

Adiponectin and peptide YY in the fasting blue fox (Alopex lagopus)

Adiponectin (Acrp30) and peptide YY (PYY) are weight-regulatory hormones participating in the control of energy homeostasis. This study investigated the effects of long-term wintertime fasting on plasma Acrp30 and PYY levels in the carnivorous blue fox, a farm-bred variant of the arctic fox (Alopex lagopus). Plasma Acrp30 and PYY concentrations were determined with radioimmunoassays during a 22-day period of fasting, which led to a 20.3% reduction in body mass of the animals (n=32). Sixteen fed blue foxes served as the control group. Acrp30 and PYY were present in blue fox plasma at similar or lower levels as reported previously for other mammals. Fasting had no acute effects on Acrp30 or PYY concentrations of the blue foxes. However, the Acrp30 levels of the fasted blue foxes were 24%-48% higher than in the fed animals between days 8-22 of fasting. Fasted blue foxes also had 6.2-fold higher plasma PYY concentrations after 15 days of fasting. Acrp30 and PYY seem to play roles in the body weight-regulation of the blue fox during long-term fasting, but their specific functions and physiological significance remain to be determined.     

Dysgonomonas hofstadii sp. nov., isolated from a human clinical source

A Gram-negative staining, facultative anaerobic, cocco-bacillus-shaped organism was isolated from a post-operative abdominal wound. Based on morphological and biochemical criteria, strain MX 1040 ( = CCUG 54731^T) was tentatively identified as Bacteroidaceae but did not correspond to any recognized species of this family. Comparative 16S rRNA gene sequencing analysis demonstrated the organism to be related to species of the genus Dysgonomonas, although sequence divergence values of >5% with the other members of this genus demonstrated the organism to represent a novel species. Phylogenetic analysis revealed the novel organism to be most closely related to Dysgonomonas gadei. The major long-chain cellular fatty acids of the novel species consisted of iso-C_14:0, anteiso-C_15:0, C_16:0, and iso-C_16:0. Based on the phenotypic criteria and phylogenetic considerations, it is proposed that strain MX 1040 from a human clinical source represents a new species of the genus Dysgonomonas, as Dysgonomonas hofstadii sp. nov. The type strain of D. hofstadii is CCUG 54731^T ( = CCM 7606^T).     

Selective fatty acid mobilization in the American mink (Mustela vison) during food deprivation

The mobilization of fatty acids (FAs) during food deprivation is a selective process in laboratory rodents and humans. The site-specific differences in adipose tissue functions - e.g. energy storage versus insulation - should also affect the use of different FAs. To study this, 16 female minks were randomly assigned into the control group or fasted for 5 days. Preferential mobilization of n-3 polyunsaturated FAs (PUFAs) during fasting caused a decrease in the n-3/n-6 PUFA ratio in fat and liver. In addition, the minks utilized short-chain FAs efficiently in all fat depots, but long-chain FAs - 20:0, 20:1n-11, 20:1n-9, 22:1n-11 and 24:1n-9 - were preserved. The number of double bonds in the FA chain correlated positively with mobilization rate in the retroperitoneal fat. The observed negative correlation between mobilization rate and the location of the first double bond from the methyl end may be due to peroxisomal chain-shortening of long-chain FAs and not the double bond position per se. As a result, minks are able to preserve a low melting point and fluidity of the subcutaneous fat depots, which would be essential to a Northern semi-aquatic mammal.     

Physiological adaptations to fasting in an actively wintering canid, the Arctic blue fox (Alopex lagopus)

This study investigated the physiological adaptations to fasting using the farmed blue fox (Alopex lagopus) as a model for the endangered wild arctic fox. Sixteen blue foxes were fed throughout the winter and 32 blue foxes were fasted for 22 d in Nov-Dec 2002. Half of the fasted blue foxes were food-deprived again for 22 d in Jan-Feb 2003. The farmed blue fox lost weight at a slower rate (0.97-1.02% body mass d(-1)) than observed previously in the arctic fox, possibly due to its higher initial body fat content. The animals experienced occasional fasting-induced hypoglycaemia, but their locomotor activity was not affected. The plasma triacylglycerol and glycerol concentrations were elevated during phase II of fasting indicating stimulated lipolysis, probably induced by the high growth hormone concentrations. The total cholesterol, HDL- and LDL-cholesterol, urea, uric acid and total protein levels and the urea:creatinine ratio decreased during fasting. Although the plasma levels of some essential amino acids increased, the blue foxes did not enter phase III of starvation characterized by stimulated proteolysis during either of the 22-d fasting procedures. Instead of excessive protein catabolism, it is liver dysfunction, indicated by the increased plasma bilirubin levels and alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase activities, that may limit the duration of fasting in the species.     

Morningness propensity in young adults born prematurely: the Helsinki study of very low birth weight adults

The authors explored morningness-eveningness propensity in adults born prematurely at very low birth weight (VLBW; 相似文献