LKB1 and the regulation of malonyl-CoA and fatty acid oxidation in muscle

5'-AMP-activated protein kinase (AMPK), by way of its inhibition of acetyl-CoA carboxylase (ACC), plays an important role in regulating malonyl-CoA levels and the rate of fatty acid oxidation in skeletal and cardiac muscle. In these tissues, LKB1 is the major AMPK kinase and is therefore critical for AMPK activation. The purpose of this study was to determine how the lack of muscle LKB1 would affect malonyl-CoA levels and/or fatty-acid oxidation. Comparing wild-type (WT) and skeletal/cardiac muscle-specific LKB1 knockout (KO) mice, we found that the 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR)-stimulated decrease in malonyl-CoA levels in WT heart and quadriceps muscles was entirely dependent on the presence of LKB1, as was the AICAR-induced increase in fatty-acid oxidation in EDL muscles in vitro, since these responses were not observed in KO mice. Likewise, the decrease in malonyl-CoA levels after muscle contraction was attenuated in KO gastrocnemius muscles, suggesting that LKB1 plays an important role in promoting the inhibition of ACC, likely by activation of AMPK. However, since ACC phosphorylation still increased and malonyl-CoA levels decreased in KO muscles (albeit not to the levels observed in WT mice), whereas AMPK phosphorylation was entirely unresponsive, LKB1/AMPK signaling cannot be considered the sole mechanism for inhibiting ACC during and after muscle activity. Regardless, our results suggest that LKB1 is an important regulator of malonyl-CoA levels and fatty acid oxidation in skeletal muscle.

An integrated methodology for recording uncertainties about environmental data

Understanding the limitations of environmental data is essential both for managing environmental systems effectively and for encouraging the responsible use of scientific research when knowledge is limited and priorities are varied. Using a combination of quantitative and qualitative techniques for assessing probabilities, and acknowledging the importance of scenarios where probabilities cannot be determined, an integrated methodology is presented for handling uncertainties about environmental data. The methodology is based on a fourfold distinction between the empirical quality of data (and the ancillary information, such as 'scale', required to interpret this), the sources of uncertainty in data, the 'fitness for use' of the data, and the quality or 'goodness' of an uncertainty model.

Running performance in middle-school runners

AIM

This study examined the relationship of 3-km run time to indices of aerobic and anaerobic ability in 9 male runners (13.4+/-0.6 years, mean+/-SD).

METHODS

Anthropometric measurements were made, and an exercise test to determine running economy at 187 m x min(-1) and (.-)VO(2max) were assessed on a treadmill. On a separate day, 2 55-m sprints followed by a 3-km run were performed on a 200-m indoor track. Capillary blood samples were obtained from a finger tip immediately after the run to determine blood lactate level. Fractional utilization (%(.-)VO(2max) used during the 3-km run) was calculated. Correlations were used to examine the relationship between run time and the physiological measurements.

RESULTS

Mean values for (.-)VO(2), HR and RER at maximal exercise were 61.7+/-4.4 ml x kg(-1)xmin(-1), 198.9+/-6.7 b x min(-1), and 1.16+/-0.04, respectively. The average time to run 3 km was 13.27+/-0.97 min (90.1+/-7.2% of (.-)VO(2max)). Post-run blood lactate level was 8.3+/-3.2 mmol x L(-1) and was significantly related (r=-0.73, p=0.02) to 3-km time. Fractional utilization tended to be related (r=-0.56, p=0.12) to time.

CONCLUSIONS

In this age group the ability to run at a high percentage of (.-)VO(2max) and tolerate a high blood lactate appear to be important determinants of running performance in young male runners.

Genetic loading in familial migraine with aura

Migraine with aura (MA) arises from a combination of genetic and environmental factors. The sibling risk, age at onset, and aura type were compared in 54 MA probands categorised by family history of MA. Three family types were ascertained each having an MA proband and: (1) an MA parent and MA offspring (three generation; n=15), (2) either an MA parent or an MA offspring (two generation; n=20), and (3) neither an MA parent nor an MA offspring (one generation; n=19). The crude recurrence risk to siblings of probands was 2.7-fold higher in three generation compared with two generation MA families (chi(2)=6.24, p=0.0125) and 4.8-fold higher in three generation compared with one generation MA families (chi(2)=9.95, p<0.002). The mean age at onset decreased with an increase in genetic load. The MA probands from three generation families were significantly younger than probands from the one generation families (F=5.14, p=0.030). MA probands from three generation families were more likely to report more than one type of aura than MA probands from two generation families (chi(2)=4.44, p=0.035). The significant difference in genetic loading and the earlier age at onset in the three generation families add further evidence for a genetic basis for MA and the difference in sibling risks demonstrates that the MA population is heterogeneous.

Interspecific hybridization induced amplification of Mdm2 on double minutes in a Mus hybrid

We report a case of interspecific hybridization induced amplification of Chromosome 10 on double minutes (dm) in the karyotype of a hybrid Mus embryo. Stable, non-mosaic dm were previously found in tissues of a 16.5-day Mus Musculus x Mus Caroli hybrid (Graves, 1984). Dm in tissues of the hybrid was of interest to us because of previous reports of genomic instability in interspecific hybrids (O'Neill et al., 1998) and thus we decided to characterize the dm in the hybrid karyotypes. Whole chromosome painting of the hybrid cell lines showed amplification of Chromosome 10 sequences. Southern analysis with a probe for the candidate gene Mdm2 showed amplification of the paternal allele of this oncogene. Overexpression of Mdm2 was confirmed by a western analysis that also showed an associated inactivation of the tumor suppressor, Trp53. Evidence indicates that the event leading to the instability observed was an early adaptive response to stress on the genome, i.e. interspecific hybridization.

An unusual presentation of tarsal tunnel syndrome caused by an inflatable ice hockey skate

BACKGROUND

Tarsal tunnel syndrome is a rare form of entrapment neuropathy. In athletes, it is usually the result of repetitive activity, local injury or a space-occupying lesion. Rarely, athletic footwear has been described as the primary cause of this syndrome.

METHODS

A 37-year-old male recreational hockey player was examined clinically and electrophysiologically because of spreading numbness in the toes of his left foot while playing hockey and wearing inflatable ice hockey skates designed to promote a better fit.

RESULTS

Clinical and electrophysiological studies revealed evidence of left medial and lateral plantar nerve involvement. Reduced amplitudes of mixed and motor plantar nerve responses with fibrillation potentials and positive sharp waves and no evidence of conduction block suggest that the primary pathology was axonal loss. Follow-up examination showed significant clinical and electrophysiological improvement after the patient stopped wearing his inflatable ice hockey skates.

CONCLUSION

We report an unusual case of tarsal tunnel syndrome caused by an inflatable ice hockey skate. The patient improved clinically and electrophysiologically when he stopped wearing the boot.

Migraine with aura is not linked to the FHM gene CACNA1A or the chromosomal region, 19p13

Two microsatellite markers, tightly linked to CACNA1A, were genotyped in migraine with aura (MA) families to determine if this gene, which underlies the 19p13 linked forms of familial hemiplegic migraine, is also linked to MA. Two-point parametric lod and nonparametric linkage scores did not support linkage. Transmission disequilibrium testing provided no evidence for linkage of MA to CACNA1A. In a large dataset of 64 Canadian MA families, the authors did not find evidence to support an MA susceptibility gene in the region of 19p13.

Attainment of maximal exercise criteria in boys and men

BACKGROUND

This study tested the hypothesis that the occurrence of a VO(2) plateau at maximal exercise would be greater in men versus boys. Secondary indicators of maximal effort also were examined.

METHODS

Sixteen boys (10.7+/-0.6 yrs) and 21 men (22.5+/-2.0 yrs) performed a graded exercise test on a treadmill at a constant speed of 8.04 km x hr(-1) with 2.5% increments in elevation. The men also performed a second test at 11.26 km x hr(-1) with similar increases in slope.

RESULTS

At 8.04 km x hr(-1) , VO(2) max was 52.3+/-6.0 and 52.5+/-5.1 ml x kg(-1) x min(-1) in boys and men, respectively (p>0.05). In the men, VO(2) max (53.3+/-5.4 ml x kg(-1) x min(-1) ) was higher (p<0.05) in the faster protocol. The percentage of men achieving the criterion was nearly double the percentage of boys (23.8 vs 12.5%), although the difference was not significant. Age-specific criteria heart rate (HR) and respiratory exchange ratio (RER) were achieved in a similar manner; however, more men (100%) than boys (86.7%) achieved an age-specific blood lactate (BLa) criterion (p<0.05). Plateau achievement increased to 33.0% in the 11.26 km x hr(-1) protocol, but was not significantly different from 8.04 km x hr(-1). HR, RER and BLa criteria achievement were comparable.

CONCLUSIONS

Maturation may influence the achievement of a plateau and BLa criteria, but not age-specific criteria for RER or HR.

Isolated brachialis wasting: an unusual presentation of neuralgic amyotrophy

Although neuralgic amyotrophy can selectively affect discrete components of the brachial plexus including individual peripheral nerves, involvement of an individual nerve fascicle is rare. Discrete fascicular musculocutaneous neuropathy as a manifestation of neuralgic amyotrophy has not previously been reported to our knowledge. We report two cases of otherwise typical neuralgic amyotrophy with isolated brachialis muscle wasting. Abnormal spontaneous activity, motor unit remodeling, or both, was observed only in the brachialis muscle. Lateral antebrachial cutaneous nerve conduction studies were normal. These cases serve to broaden the spectrum of the clinical presentation of neuralgic amyotrophy.

Analysis of the origin of through-space proton NMR deshielding by selected organic functional groups

GIAO-HF and IGLO-DFT computations of isotropic magnetic shieldings were used to map the NMR shielding environments of small molecules exemplifying selected organic functional groups. Two different probes were employed: a methane molecule and NICS (nucleus-independent chemical shifts) based on computed absolute isotropic shieldings. The reason for the different results obtained using these two probes is perturbation of the wave function by the proximity of methane to the pi bond, as analyzed by the localized orbital contributions to the shieldings. [structure: see text]

Body and spirit: Religion, spirituality, and health among adolescents

Religion and spirituality are important in the lives of many adolescents. This article traces patterns of adolescent religious/spiritual belief and practice and summarizes theories about religious development as they pertain to this age group. Data are provided that explore possible relationships between religion and health-related behavior among adolescents. Much of this data shows that greater religiosity/spirituality may be associated with less involvement in high-risk behaviors and more involvement in health-promoting behaviors. Implications of these data are discussed as well as possible negative roles that religion may play in youths' lives. The doctor's role in approaching religion and spirituality with patients is controversial. Health care professionals should be prepared to discuss these issues with adolescents for whom they are important, especially with patients who are hospitalized. Yet, doctors should be sensitive to those adolescents who may not want to delve into spiritual/religious issues in a health care setting.

Ribosome biogenesis: stripping for AAAction?

Ribosomal subunits are assembled in the nucleolus before being transported to the cytoplasm. Recent work has identified both a protein that may play a key role in restructuring the large, 60S subunit prior to transport and factors that facilitate transport itself.

Protein transport: two translocons are better than one

The translocon is the gateway to the endoplasmic reticulum (ER). In yeast this is the Sec61p complex. However, new evidence suggests that a second translocon containing the Sec61p homolog Ssh1p provides important flexibility to the ER translocation machinery.

Hospitalization for ambulatory care-sensitive conditions: a method for comparative access and quality studies using routinely collected statistics

BACKGROUND

Appropriate and timely provision of ambulatory care is an important factor in maintaining population health and in avoiding unneccessary hospital use. This article describes conditions for which hospitalization rates have a strong and inverse relationship to access to high-quality ambulatory care.

METHODS

Three panels of Canadian physicians following different consensus techniques selected conditions for which the relative risk of hospitalization is inversely related to ambulatory care access.

PRINCIPAL FINDINGS

All panels identified asthma, angina pectoris, congestive heart failure, otitis media, gastric ulcer, pelvic inflammatory disease, malignant hypertension, and immunization-preventable infections as ambulatory care-sensitive admissions. These conditions strongly overlap with lists developed for similar purposes in the U.S. and England.

INTERPRETATION

Ambulatory care-sensitive conditions represent an intermediate health outcome. They are distinct from inappropriate hospitalizations. They may be useful for measuring the impact of health care policy, and for performance measurement or audit.

Conduction block in neuralgic amyotrophy

We describe two cases of neuralgic amyotrophy with electrophysiological evidence of conduction block across the lower trunk of the brachial plexus. Low-output impedance stimulation of the cervical spinal roots in combination with collision was used to accurately demonstrate the conduction block. Complete electrophysiological recovery of the conduction block occurred within 3 months. Early clinical and electrophysiological recovery in both patients suggests that, in some cases, demyelination may predominate early in the course of neuralgic amyotrophy.

When the perpetrator gets killed: effects of observing the death of a handgun user in a televised public service announcement

This study evaluates the cognitive effects of an anti-handgun violence public service announcement (PSA) on sixth-, seventh-, and eighth-grade students (N = 294). Participants were randomly assigned to a treatment group, which viewed a PSA depicting the death of an aggressive handgun user, or a comparison group, which viewed identical content except that the PSA showed no negative consequence for the handgun user. Logistic regression analysis, adjusting for race and gender, revealed that the treatment group was more likely to report negative expected outcomes for aggressively using a handgun and lower behavioral intentions to aggressively use a handgun compared with the comparison group. These findings suggest that observing handgun violence on television that depicts death as a negative physical consequence for the perpetrator may produce lower handgun-encouraging beliefs compared with observing no consequence for the perpetrator--the norm for most televised violence today.

Handshaking, gender, personality, and first impressions

Although people's handshakes are thought to reflect their personality and influence our first impressions of them, these relations have seldom been formally investigated. One hundred twelve participants had their hand shaken twice by 4 trained coders (2 men and 2 women) and completed 4 personality measures. The participants' handshakes were stable and consistent across time and coders. There were also gender differences on most of the handshaking characteristics. A firm handshake was related positively to extraversion and emotional expressiveness and negatively to shyness and neuroticism; it was also positively related to openness to experience, but only for women. Finally, handshake characteristics were related to the impressions of the participants formed by the coders. These results demonstrate that personality traits, assessed through self-report, can predict specific behaviors assessed by trained observers. The pattern of relations among openness, gender, handshaking, and first impressions suggests that a firm handshake may be an effective form of self-promotion for women.

The development of a post-baccalaureate certificate program in molecular diagnostics

A post-baccalaureate certificate program in diagnostic molecular sciences was created in 1995 by the Diagnostic Genetic Sciences Program in the School of Allied Health at the University of Connecticut. The required on-campus lecture and laboratory courses include basic laboratory techniques, health care issues, cell biology, immunology, human genetics, research, management, and molecular diagnostic techniques and laboratory in molecular diagnostics. These courses precede a 6-month, full-time practicum at an affiliated full-service molecular laboratory. The practicum includes amplification and blotting methods, a research project, and a choice of specialized electives including DNA sequencing, mutagenesis, in situ hybridization methods, or molecular diagnostic applications in microbiology. Graduates of the program are immediately eligible to sit for the National Credentialing Agency examination in molecular biology to obtain the credential Clinical Laboratory Specialist in Molecular Biology (CLSp(MB). This description of the University of Connecticut program may assist other laboratory science programs in creating similar curricula.

Nuclear export of yeast signal recognition particle lacking Srp54p by the Xpo1p/Crm1p NES-dependent pathway

BACKGROUND

The movement of macromolecules through the nuclear pores requires energy and transport receptors that bind both cargo and nuclear pores. Different molecules/complexes often require different transport receptors. The signal recognition particle (SRP) is a conserved cytosolic ribonucleoprotein that targets proteins to the endoplasmic reticulum. Previous studies have shown that the export of SRP RNA from the nucleus requires trans-acting factors and that SRP may be at least partly assembled in the nucleus, but little else is known about how it is assembled and exported into the cytoplasm.

RESULTS

Of the six proteins that constitute the yeast SRP, we found that all except Srp54p were imported into the nucleus. Four of these had nucleolar pools. The same four proteins are required for stability of the yeast SRP RNA scR1, suggesting that they assemble with the RNA in the nucleus to form a central core SRP. This core SRP was a competent export substrate. Of the remaining components, Sec65p entered the nucleus and was assembled onto the core particle there, whereas Srp54p was solely cytoplasmic. The export of SRP from the nucleus required the transport receptor Xpo1p/Crm1p and Yrb2p, both components of the pathway that exports leucine-rich nuclear export signal (NES)-containing proteins from the nucleus.

CONCLUSIONS

The SRP is assembled in the nucleus into a complex lacking only Srp54p. It is then exported through the NES pathway into the cytoplasm where Srp54p binds to it. This transport route for a ribonucleoprotein complex is so far unique in yeast.