Resistance Training Preserves Fat‐free Mass Without Impacting Changes in Protein Metabolism After Weight Loss in Older Women

This study assessed the effects of resistance training (RT) on energy restriction–induced changes in body composition, protein metabolism, and the fractional synthesis rate of mixed muscle proteins (FSRm) in postmenopausal, overweight women. Sixteen women (age 68 ± 1 years, BMI 29 ± 1 kg/m², mean ± s.e.m.) completed a 16‐week controlled diet study. Each woman consumed 1.0 g protein/kg/day. At baseline (weeks B1–B3) and poststudy (weeks RT12–RT13), energy intake matched each subject's need and during weeks RT1–RT11 was hypoenergetic by 2,092 kJ/day (500 kcal/day). From weeks RT1 to RT13, eight women performed RT 3 day/week (RT group) and eight women remained sedentary (SED group). RT did not influence the energy restriction–induced decrease in body mass (SED ?5.8 ± 0.6 kg; RT ?5.0 ± 0.2 kg) and fat mass (SED ?4.1 ± 0.9 kg; RT ?4.7 ± 0.5 kg). Fat free mass (FFM) and total body water decreased in SED (?1.6 ± 0.4 and ?2.1 ± 0.5 kg) and were unchanged in RT (?0.3 ± 0.4 and ?0.4 ± 0.7 kg) (group‐by‐time, P ≤ 0.05 and P = 0.07, respectively). Protein–mineral mass did not change in either group (SED 0.4 ± 0.2 kg; RT 0.1 ± 0.4 kg). Nitrogen balance, positive at baseline (2.2 ± 0.3 g N/day), was unchanged poststudy. After body mass loss, postabsorptive (PA) and postprandial (PP) leucine turnover, synthesis, and breakdown decreased. Leucine oxidation and balance were not changed. PA and total (PA + PP) FSRm in the vastus lateralis were higher after weight loss. RT did not influence these protein metabolism responses. In summary, RT helps older women preserve FFM during body mass loss. The comparable whole‐body nitrogen retentions, leucine kinetics, and FSRm between groups are consistent with the lack of differential protein–mineral mass change.     

Isoform-specific localization of voltage-gated K+ channels to distinct lipid raft populations. Targeting of Kv1.5 to caveolae

The precise subcellular localization of ion channels is often necessary to ensure rapid and efficient integration of both intracellular and extracellular signaling events. Recently, we have identified lipid raft association as a novel mechanism for the subcellular sorting of specific voltage-gated K(+) channels to regions of the membrane rich in signaling complexes. Here, we demonstrate isoform-specific targeting of voltage-gated K(+) (Kv) channels to distinct lipid raft populations with the finding that Kv1.5 specifically targets to caveolae. Multiple lines of evidence indicate that Kv1.5 and Kv2.1 exist in distinct raft domains: 1) channel/raft association shows differential sensitivity to increasing concentrations of Triton X-100; 2) unlike Kv2.1, Kv1.5 colocalizes with caveolin on the cell surface and redistributes with caveolin following microtubule disruption; and 3) immunoisolation of caveolae copurifies Kv1.5 channel. Both depletion of cellular cholesterol and inhibition of sphingolipid synthesis alter Kv1.5 channel function by inducing a hyperpolarizing shift in the voltage dependence of activation and inactivation. The differential targeting of Kv channel subtypes to caveolar and noncaveolar rafts within a single membrane represents a unique mechanism of compartmentalization, which may permit isoform-specific modulation of K(+) channel function.     

Longliners,black-browed albatross mortality and bait scavenging in Falkland Island waters: what is the relationship?

The rate of foraging attempts by black–browed albatross on baited hooks during Spanish-system (demersal) longline-setting operations, and a range of environmental and operational variables were used to investigate the relationship between their foraging behaviour and their mortality level. Logistic regression highlighted that a complex range of environmental and operational variables and black-browed albatross abundance combined to determine their mortality level. Our results suggest that, examined over a relatively short time period with minimal environmental variation, the rate of black-browed albatross foraging attempts during line-setting significantly affects their level of mortality. However, as a range of variables influence mortality, until targeted experimental studies are conducted, we suggest that caution should be exercised when using the rate of black-browed albatross foraging attempts as an index of their mortality.     

The cellular location of proteases in Candida albicans

Vacuoles prepared from yeast cells of Candida albicans were enriched in proteinase ycaB (EC 3.4.21.48) but not in aminopeptidase or beta-glucosidase. Proteinase ycaB, assayed in situ, increased 1.5-fold during starvation whereas aminopeptidase activity decreased by 25%. Proteinase ycaB increased a further 1.5-fold during germ-tube formation.     

Strategies for automated sequencing of human mitochondrial DNA directly from PCR products.

A rapid, robust and sensitive method has been developed for the amplification and direct sequencing of human mitochondrial DNA. A 403-bp hypervariable segment was amplified by two successive rounds of nested PCR. This was then sequenced by the dideoxy chain termination method using dye-labeled universal sequencing primers in conjunction with an automated DNA sequencer. This paper describes the assessment of four different strategies for this amplification and sequencing process. Optimal results were obtained by immobilizing the biotinylated PCR product on Dynabeads followed by solid-phase sequencing with Sequenase. Degraded samples and those containing trace amounts of DNA such as extracts from hair shafts can be analyzed by this method.     

Effects of grouping and fighting on the reproductive tracts of male white-footed mice (Peromyscus leucopus)

Summary Adult, male white-footed mice (Peromyscus leucopus) were subjected to a variety of social situations ranging from isolation during the 20 day experimental period to constant contact with both females and other adult males. Contacts included grouping (three or four males per cage) and exposure to fighters (once daily for 20 minutes). The following measurements were recorded: weights of the body, testes, epididymides, vesicular glands, vesicular gland tissue (wet and dry), seminal fluid of the vesicular gland, adrenal glands, and baculum; spermatozoan reserves of the testes and epididymides. Grouping significantly affected both the weight and spermatozoan reserves of the testes and epididymides, as well as both the tissue and seminal fluid weight of the vesicular glands. The results suggested a graded effect of all treatments on the reproductive tract. In order of magnitude of the associated response, from none to greatest, the treatments may be ranked as follows: pairing with females, isolating, handling, fighting, and grouping. All reproductive parameters measured showed this general ranking, suggesting that the response to the various treatments was similar and differed only quantitatively. The results further suggested decreased secretion of LH and testosterone, although measurements of testosterone did not substantiate this conclusion. The lack of significant effects of grouping on adrenal gland weights strengthened the argument that adrenal involvement is not a necessary adjunct to the suppression of the reproductive tract in groupedPeromyscus, but the adrenal may be involved if contacts between males result in overt fighting.     

Globus and headache: common symptoms of the irritable bowel syndrome.

Persons with the irritable bowel syndrome (IBS) have a significantly higher prevalence of globus and migraine-like headache than age-matched control subjects. On the other hand, persons with organic disease of the esophagus or colon may have a reduced prevalence of functional symptoms involving the opposite end of the gastrointestinal tract. The dispersed pattern of symptoms in IBS suggests that some agent, such as a hormone, may be acting systemically.