Factors to Reduce Drug-Related Recidivism Among Paroled Methamphetamine Users in Japan: 10-Year Data Analysis

This study explored factors to reduce drug-related recidivism among paroled methamphetamine users in Japan, especially the significance of continuing care and motivation, internationally shown as positively related to better treatment outcomes. Cox proportional hazards regression analysis was performed on 10-year drug-related recidivism data from 4,084 methamphetamine users paroled in 2007 who received a mandatory educational program conducted by professional and volunteer probation officers. Independent variables included participant characteristics, an index of motivation, and the length of parole as a substitute for the duration of continuing care with consideration of the Japanese legal system structures and socio-cultural context. Older age, lower number of previous prison sentences, shorter imprisonment, longer parole, and index of higher motivation were significantly and negatively associated with drug-related recidivism. The results indicate the benefit of continuing care and motivation on treatment outcomes, regardless of the differences in socio-cultural context and criminal justice system.

Changes in choriocapillaris structure occurring in idiopathic macular hole before and after vitrectomy

PURPOSE

The aim of this study was to analyze the anatomical choroidal vascular layers and the changes in idiopathic macular hole (IMH) eyes over time after vitrectomy.

METHODS

This is a retrospective observational case-control study. Fifteen eyes from 15 patients who received vitrectomy for IMH and age-matched 15 eyes from 15 healthy controls were enrolled in this study. Retinal and choroidal structures were quantitatively analyzed before vitrectomy and 1 and 2 months after surgery using spectral domain-optical coherence tomography. Each choroidal vascular layer was divided into the choriocapillaris, Sattler's layer, and Haller's layer, and then, the choroidal area (CA), luminal area (LA), stromal area (SA), and central choroidal thickness (CCT) were calculated using binarization techniques. The ratio of LA to CA was defined as the L/C ratio.

RESULTS

The CA, LA, and L/C ratios were 36.9 ± 6.2, 23.4 ± 5.0, and 63.1 ± 7.2 in the choriocapillaris of IMH and were 47.3 ± 6.6, 38.3 ± 5.6, and 80.9 ± 4.1 in that of control eyes, respectively. Those values were significantly lower in IMH eyes than in control eyes (each P < 0.01), whereas there was no significant difference in total choroid, Sattler's layer, and Haller's layer or CCT. The ellipsoid zone defect length showed a significant negative correlation with the L/C ratio in total choroid and with CA and LA in the choriocapillaris of IMH (R =  - 0.61, P < 0.05, R =  - 0.77, P < 0.01, and R =  - 0.71, P < 0.01, respectively). In the choriocapillaris, the LA were 23.4 ± 5.0, 27.7 ± 3.8, and 30.9 ± 4.4, and the L/C ratios were 63.1 ± 7.2, 74.3 ± 6.4, and 76.6 ± 5.4 at baseline, 1 month, and 2 months after vitrectomy, respectively. Those values showed a significant increase over time after surgery (each P < 0.05), whereas the other choroidal layers did not alter consistently with respect to changes in choroidal structure.

CONCLUSIONS

The current OCT-based study demonstrated that the choriocapillaris was exclusively disrupted between choroidal vascular structures in IMH, which may correlate with the ellipsoid zone defect. Furthermore, the L/C ratio of choriocapillaris recovered after IMH repair, suggesting an improved balance between supply and demand of oxygen that has collapsed due to temporary loss of central retinal function by IMH.

Peripapillary circulatory dysfunction precedes structural loss in treatment-naive diabetic retinopathy

PURPOSE

The aim of this study was to compare the timing of peripapillary vascular damage between functional and structural parameters and examine their involvement with neurovascular coupling at different stages of diabetic retinopathy (DR).

METHODS

One hundred ninety eyes of 143 patients with type 2 diabetes mellitus (DM) and 88 healthy control eyes were enrolled. Eyes of DM patients were divided into 3 stages with no diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR). NPDR and PDR eyes were treatment-naive. OCT angiography was used to calculate radial peripapillary capillary (RPC)-flux index (FI) and RPC-perfusion density (PD). Spectral domain OCT was used to measure retinal nerve fiber layer (RNFL) thickness within the corresponding RPC areas.

RESULTS

RPC-FI significantly decreased in NDR eyes compared to control eyes and thereafter remained unchanged among DM (NDR, NPDR, and PDR) eyes. In contrast, RPC-PD stayed unaltered between control and NDR eyes and significantly decreased in NPDR followed by PDR eyes at similar levels. From control to NPDR eyes, RNFL thickness showed positive correlations with both RPC-FI and RPC-PD, indicative of functional and structural neurovascular coupling. These vascular parameters were also correlated with each other in control and NPDR eyes but not NDR eyes, consistent with the difference in the timing of vascular damage between functional and structural parameters.

CONCLUSIONS

Circulatory dysfunction preceded structural loss while maintaining peripapillary neurovascular coupling during progression of DR stages. RPC-FI would likely be more sensitive than RPC-PD in detecting early vascular damage in DR.

Involvements of choroidal vascular structures with local treatments in patients with diabetic macular edema

PURPOSE

To examine changes of the choroidal morphology in patients with diabetic macular edema (DME) before and after local treatments.

METHODS

This study was on 20 eyes with DME, observed for more than 24 months. All patients underwent laser photocoagulation (Laser), sub-tenon triamcinolone acetonide injection (TA), or intravitreal aflibercept injection (IVA). Central macular and choroidal thicknesses (CMT/CCT), and choroidal vascular structures consisting of the total choroidal area (TCA), luminal area (LA), and stromal area (SA) were measured by a binarization method. The ratios of LA in TCA were eventually determined as the L/C ratio in each case.

RESULTS

The L/C ratio significantly decreased for 24 months in patients with DME (p = 0.01), whereas no significant differences were noted in other parameters including TCA, LA, SA, or CCT. Among patients treated with Laser ± TA ± IVA, a significant correlation was found between a high L/C ratio at pretreatment and a lower cumulative number of injections (1-2 times/24 months) (p = 0.04). The L/C ratio in pretreatment showed a significantly inverse correlation with CMT (-0.60, p = 0.02) and subsequent BCVA (logMAR) (-0.59, p = 0.03).

CONCLUSION

This study highlighted that the L/C ratio in pretreatment might predict a change of the visual acuity in DME.

Factors based on optical coherence tomography correlated with vision impairment in diabetic patients

The aim of this study is to evaluate the relationship between retinal structures and visual acuity in diabetic patients using optical coherence tomography (OCT) and OCT angiography (OCTA). This study was a retrospective observational study conducted at a single medical center in Japan. Evaluation of retinal images was analyzed using spectral domain OCT. Twelve factors including central retinal thickness, length of disorganization of retinal inner layer (DRIL), number of inner hyperreflective foci, number of outer hyperreflective foci, height of intraretinal fluid, height of subretinal fluid, length of external limiting membrane disruption, length of external ellipsoid zone (EZ) disruption, vessel density of superficial capillary plexus (SCP), foveal avascular zone (FAZ) area, and FAZ circularity were analyzed based on OCT/OCTA findings. Multivariate analysis was used to investigate the OCT-based factors that could be correlated with poor visual acuity in treatment-naïve diabetic eyes. A total of 183 eyes of 123 diabetic patients with type 2 diabetes (mean age 61.9 ± 12.3 years, 66 men and 57 women) and 62 eyes of 55 control subjects (mean age 64.4 ± 12.5 years, 15 men and 40 women) was enrolled in this study. Multiple regression analysis showed that OCT-based factors correlated with visual acuity were length of DRIL (β = 0.24, P < 0.01), length of EZ disruption (β = 0.35, P < 0.001), and FAZ circularity (β =  - 0.14, P < 0.05). The other factors showed no significant correlation. In conclusion, the length of DRIL, length of EZ disruption, and FAZ circularity measured by OCT were identified as related factors for visual impairment in treatment-naïve diabetic eyes.

Cognitive Distortions Among Sexual Offenders Against Women in Japan

Research in Western countries has indicated that the cognitive distortions of sexual offenders play an etiological and maintenance role in offending. The present study examines whether the cognitive distortions hypothesized by previous Western studies can be found in Japanese sexual offenders against women. This study used the questionnaire administered by probation officers in the special cognitive-behavioral treatment programs for sexual offenders, which have been implemented since 2006 in Japan. Participants in the offender group were 80 Japanese male probationers and parolees (more than 19 years old, M age = 34.6, SD = 8.8) convicted of rape (n = 39) or indecent assault (n = 41). All of them attended special treatment programs at probation offices. The non-offender comparison group consisted of 95 Japanese male probation officers and police officers (M age = 35.5, SD = 11.4). A factor analysis of the questionnaire responses extracted three factors: Blaming the Victim, Minimization, and Avoidance of Responsibility. The data analyses showed that sexual offenders scored significantly higher than non-offender participants on the three subscales. No significant differences were found among four sexual offender groups classified as rapists or indecent assaulters and with or without previous convictions for sexual offenses. In conclusion, the results of this study indicate that rapists and indecent assaulters placed on probation or parole in Japan hold cognitive distortions concerning sexual assaults against women than the control group of probation and police officers. The findings of this study also suggest that cognitive distortions exhibited by sexual offenders against women transcend cultural divides.

Alteration of choroidal vascular structure in diabetic retinopathy

PURPOSE

The aim of this study was to analyse choroidal structures in normal patients and patients with diabetes with various severities of diabetic retinopathy (DR).

METHODS

This is a retrospective observation case control study. Three hundred and forty-two diabetic eyes, and age-matched 112 eyes without diabetes mellitus (DM) were enrolled in this study. Patients with DM were classified into no DR, mild/moderate non-proliferative DR (mNPDR), severe NPDR and proliferative DR (PDR). Patients with DM were further divided into two groups based on information regarding systemic DM treatment situation: DM-treated and untreated groups. Central choroidal thickness (CCT), and total choroidal area (TCA), luminal area (LA) and stromal area (SA) were determined using enhanced depth imaging optical coherence tomography and a binarisation method, respectively. The ratio of LA in the TCA was defined as L/C ratio.

RESULTS

The haemoglobin A1c (HbA1c) value was significantly higher in the DM-untreated than in the DM-treated subjects. L/C ratio was significantly lower in all the diabetic eyes than control eyes (p<0.05). TCA, LA, L/C ratio and CCT were significantly greater in the DM-untreated than treated group (each p<0.05). In the DM-untreated group, TCA and LAs (p<0.05) and L/C ratio (p<0.01) were significantly lower in mNPDR subjects than normal controls (p<0.05). PDR in the DM-untreated group showed significantly larger SA and LA, and greater CCT than normal controls (each p<0.05).

CONCLUSIONS

These results suggest that choroidal vasculature was initially involved at an early DR, whereas thickened LA and SA were noted in advanced DR.

Alteration of layer thickness in the choroid of diabetic patients

IMPORTANCE

Choroidal thickness changes in diabetic retinopathy improve understanding the pathophysiology and managements of this disease.

BACKGROUND

To examine the choroidal layer thickness in diabetes mellitus (DM) patients and normal individuals, and to compare the findings based on medical history of systemic DM treatments, and stage of diabetic retinopathy (DR).

DESIGN

Case control study.

PARTICIPANTS

Two hundred sixty eight eyes of 134 DM patients and age-matched 72 healthy controls of 92 eyes.

METHODS

Central choroidal layer thickness (total, inner, and outer layers) was measured using enhanced depth imaging OCT. DM patients were divided into two groups; the DM treated group (88 cases), and the untreated group (46 cases). These two groups were further classified into four groups; no DR (NDR), mild/moderate non-proliferative DR (mNPDR), severe NPDR and PDR.

MAIN OUTCOME MEASURES

Comparison of subfoveal choroid layer thickness in control and diabetic patient groups.

RESULTS

Choroidal thickness measurements of diabetic eyes had strong correlation between masked raters in choroidal layers, proving high reproducibility. The total and outer choroid thicknesses in mNPDR in the DM untreated group were significantly thinner than normal controls (each P<0.05). Choroidal outer layer thickness of the severe NPDR in the DM untreated group was significantly thicker than normal controls (P<0.05). In the DM treatment group, there were no significant differences from the control group regarding choroidal layer thicknesses and all stages of DR.

CONCLUSIONS AND RELEVANCE

The choroidal thickness significantly changed in the DM untreated group, and the main anatomical changes might result from the outer layer.

First report of serotype 23B Streptococcus pneumoniae isolated from an adult patient with invasive infection in Japan

Serotype 23B Streptococcus pneumoniae was isolated from a 67-year-old Japanese patient with meningitis. This isolate was susceptible to penicillin G, while genotyped as gPISP with a mutation in a penicillin-binding motif in PBP2b. The 23B isolate was assigned to ST11996 that is related to CC439, a dominant group among serotype 23B.

A 2-year follow-up study on muscle size and dynamic strength in teenage tennis players

Growth trends in the cross-sectional area of the quadriceps femoris (CSA(QF)) and its dynamic strength in 12 teenage tennis players (six boys and six girls), aged from 10.7 to 13.2 years at the onset of the study, were investigated through a 2-year follow-up survey. CSA(QF) values at the three levels (proximal, mid, and distal to the knee joint) and dynamic torques during knee extensions at three pre-set velocities (1.05, 3.14, and 5.24 rad/s) were determined year by year, i.e., three times (T1, T2, and T3), using magnetic resonance imaging and an isokinetic dynamometer, respectively. In both genders, the CSA(QF) values at the three levels tended to increase across the measurement times, with greater gains in the boys than in the girls at the levels mid and distal to the knee joint. Among these changes, only the CSA(QF) at the level proximal to the knee joint significantly increased regardless of changes in both skeletal age and body height. The ratios of torque to the sum of CSA(QF) at the three levels (T/CSA) at 3.14 and 5.24 rad/s for the boys and at 5.24 rad/s for the girls were significantly higher in T2 and T3 than T1. Further, the relative increases in torque and T/CSA values at 3.14 and 5.24 rad/s were greater in the boys than the girls. The findings presented here indicate that young tennis players who are in the earlier stage of adolescence increase the CSA of the QF muscle beyond normally expected growth change at the level proximal to the knee joint and show a predominant development in torque generation capability during high-velocity knee extensions, with a greater gain in boys compared with girls.

Relationship between muscle strength in various isokinetic movements and kick performance among soccer players

AIM

The present study was carried out to examine relationships between muscular strength and ball velocity with respect to 3 different approach angles and focussing on both the kicking leg and the supporting leg among soccer players of different skill levels.

METHODS

Fourteen university soccer players were divided into 2 groups (superior group, average group), and kicked the ball with maximal effort towards a target 15 m away. The angles of approach to the stationary ball varied in 3 directions (free, 1.57, 2.36 rad to the kick direction). Mean ball velocity and the success rate of striking the target with the ball were measured. Maximal isokinetic and concentric muscular strength was measured in terms of motions of the knee Ext/Flex, hip Ext/Flex and hip Abd/Add using an isokinetic dynamometer.

RESULTS

The mean ball velocity at free and 1.57 rad approach angles related significantly with hip Add but not with knee Ext strength for the kicking leg. In contrast, the ball velocity at an approach angle of 2.36 rad significantly correlated with knee Ext and hip Flex of the kicking leg. Although ball velocity at the free and the 1.57 rad approach angles showed no relation to strength of the supporting leg, the ball velocity at the 2.36 rad approach angle showed a significant relationship with knee Flex, hip Ext and hip Abd strength of the supporting leg. Furthermore, the superior group had more strength variables related to performance than the average group.

CONCLUSIONS

Different approach angles would alter the requirement on muscle strength potential of both kicking and supporting leg during kicking. Especially an angled approach to the kick direction could require greater hip extension and abduction strength on the supporting leg for a higher capability for stabilizing body balance. Besides, skill level may alter the importance of muscle strength requirement to kick performance.

Natural occurrence of myofiber cytoplasmic enlargement accompanied by decrease in myonuclear number

It has been shown that changes in the nuclear number in myofibers are synchronized with myofiber size. Therefore, under some conditions, the myonuclear number is thought to be a determinant factor of myofiber size. However, we have clearly shown that denervation-induced fiber atrophy occurs without any decrease in myonuclear number, indicating that the myonuclear number is not always an important determinant factor of myofiber size. However, this was an event found under experimental conditions. In the present study, we examined the morphological features of single myofibers under normal conditions throughout the lifespan of normal mice. We discovered that the C/N ratio (cell volume/nucleus) greatly increases during the growth period and clearly decreases during the aging period. From 5 weeks to 6 months old, the myofibers undergo fiber hypertrophy accompanied by a decrease in myonuclear number. In muscle at 18 months, we found no correlation between myonuclear number and fiber cross-sectional area. These results suggest that, even under normal physiological conditions, the myonuclear number is not always a determinant factor of the myofiber size.

No decrease in myonuclear number after long-term denervation in mature mice

Age-related but not artificially induced muscle fiber atrophy has been shown to occur without any decrease in myonuclear number, although these results remain controversial. The present study was carried out to clarify whether age difference affects the degree of decrease in myonuclear number occurring with denervation-induced fiber atrophy. After denervation of 3-wk-old (young) and 4-mo-old (mature) mice, single myofibers were isolated from the plantaris muscles by alkali maceration, and their fiber cross-sectional area (CSA), myonuclear number, and cytoplasm-to-myonucleus (C/N) ratios were analyzed. Fiber CSA in both young and mature mice decreased with denervation. Myonuclear number decreased in young mice 5 and 10 days after denervation but was unchanged in mature mice 10 and 120 days after denervation. C/N ratio decreased in mature mice but was unchanged in denervated young mice. These results suggest that age differences affect the degree of decrease of myonuclear number with denervation and that fiber cytoplasmic atrophy may occur without decrease in myonuclear number.

Dietary obesity-resistance and muscle oxidative enzyme activities of the fast-twitch fibre dominant rat

OBJECTIVES

To clarify whether the muscle fibre composition and/or muscle oxidative enzyme activity are related to dietary body weight gain and abdominal fat accumulation.

METHODS

Genetically fast-twitch fibre dominant rats (FFDR) and control rats (CR) were divided into low-fat (20% of energy from fat) or high-fat (60% of energy from fat) diet groups: CR with a low-fat diet (CL); CR with a high-fat diet (CH); FFDR with a low-fat diet (FL); and FFDR with a high-fat diet (FH). After 6 weeks of following such diets, the body weight gain, abdominal fat content, food intake, muscle fibre composition and oxidative enzyme activities were estimated.

RESULTS

The total body weight gain in CH was from 18 to 62% higher than in the other groups (P<0.05) and percentage abdominal fat in CH was also from 26 to 61% higher than in the other groups (P<0.05), while the energy intake did not differ among the groups. The percentage of type IIX fibres of M. gastrocnemius in FL (33.4%) and FH (36.3%) were higher than in CL (16.8%) and CH (19.8%; P<0.05), and the type IIA fibres of M. soleus in FL (14.1%) and FH (11.8%) were higher than in CL (2.0%) and CH (3.5%; P<0.05). The citrate synthase (CS) activity of of M. plantaris in FL and FH were higher than CL (46 and 54%, respectively, P<0.05). beta-Hydroxyacyl CoA dehydrogenase (HAD) activity in FL and FH were higher than in CL (21 and 31%, respectively, P<0.05) and that in FH was higher than CH (23%, P<0.05). On the other hand, the enzyme activities of M. gastrocnemius and soleus were identical among the groups.

CONCLUSION

The FFDR was more obesity-resistant than the CR after a high-fat diet. These results suggest that the muscle oxidative capacity rather than muscle fibre composition is a possible determinant of obesity.

Relationship between mitochondrial DNA polymorphism and the individual differences in aerobic performance

This study focused on the mitochondrial DNA (mtDNA) as the genetic factor most likely to bring about the individual difference in endurance capacity or its trainability. Platelets contain mtDNA but no nuclear DNA, whereas rho(0)-HeLa cells have nuclear DNA but no mtDNA. The oxidative capacity of mitochondria in the cultured cells, which were fused rho(0)-HeLa cell with platelets obtained from individual subjects (the so-called "cybrids"), reflects the individual mtDNA polymorphism in the gene-coding region. The purpose of this study was to investigate the relationship between the oxidative capacity of cybrids and the individual difference in endurance capacity, or its trainability. Forty-one sedentary young males took part in an 8-week endurance training program. They were determined by using their VO(2 max) as an index of endurance capacity on an ergocycle before and after the endurance training program. The relations between VO(2 max) before endurance training or the change of it by endurance training and the oxidative capacity of cybrids were investigated. There was no relation between them, and two groups were drawn from all subjects, based on one standard division of their initial VO(2 max): the higher pre-VO(2 max) group (n = 6) and the lower pre-VO(2 max) group (n = 5) (51.8 +/- 3.5 ml/min/kg vs. 33.3 +/- 3.8 ml/min/kg, p < 0.01). No significant difference was found between the O(2) consumption of the cybrids in the higher initial VO(2 max) group and that in the lower initial VO(2 max) group (16.3 +/- 4.9 vs. 15.9 +/- 2.0 nmol O(2)/min/10(7) cells, NS). Furthermore, neither the cytochrome c oxidase (COX) activity nor the complex I + III activity of cybrids showed a significant difference between the two groups. The oxidative capacity of cybrids between the high trainability group (n = 6) (Delta VO(2 max) 12.1 +/- 1.6 ml/min/kg) and the low trainability group (n = 9) (Delta VO(2 max) 2.3 +/- 0.5 ml/min/kg) was also similar. Thus the mtDNA polymorphism is very unlikely to relate to the individual difference in endurance capacity or its trainability in young sedentary healthy subjects.

Endurance training under 2500-m hypoxia does not increase myoglobin content in human skeletal muscle

The present study was carried out to determine whether myoglobin (Mb) concentration ([Mb]) in human skeletal muscle is influenced by 8 weeks of endurance training under normal conditions, and under hypoxic conditions equivalent to an altitude of 2500 m. Fourteen healthy but sedentary male adults who did not participate in any regular exercise program took part in this study. They were divided into two groups according to the training regime to which they were submitted: the N group, who exercised under normobaric conditions, and the H group, who exercised under hypobaric conditions. All subjects performed an incremental cycling exercise at sea level to evaluate their maximal O2 uptake (VO2max) before and after the 8-week endurance training course period. Muscle tissue samples were obtained by needle biopsy from the vastus lateralis muscle for histochemical and biochemical analysis. Training induced an increase in VO2max in both the N and H groups (P < 0.05), although there was no significant difference in these changes between groups. The 8-week training had no effect on [Mb] in either group. Muscle fiber composition was also unaffected by the training course. In contrast, citrate synthase activity in both groups increased by [mean (SD)] 28.2 (33.3)% (N: P < 0.01) and 32.0 (18.2)% (H: P < 0.05) after training, and the number of capillaries (capillary:fiber ratio) increased by 47.7 (33.8)% (N: P < 0.01) and 32.3 (20.6)% (H: P < 0.05). There were no significant differences in these parameters between the N and H groups. These results suggest that significant improvement of aerobic potential as a result of endurance training are not accompanied by increases in [Mb] in human skeletal muscle. In addition, a lower absolute workload may not be sufficient to stimulate Mb synthesis in humans, even where endurance training is carried out under hypoxia.

Muscle function in 164 men and women aged 20--84 yr

PURPOSE

The purpose of the present study was to investigate the effect of aging in men and women on muscle functional properties, i.e., muscle force and force per unit of cross-sectional area (force/CSA).

METHODS

A total of 164 volunteers participated in this study and were divided into five groups according to their chronological age as follows: 20s (20--39 yr old), 40s, 50s, 60s, and 70s (70--84 yr old). Isokinetic (0, 60, 180, and 300 degrees.s(-1)) knee extensor and flexor peak torque, and CSA of the quadriceps femoris (QF) muscle of the mid-thigh were measured.

RESULTS

Peak torque during knee extension and flexion was inversely related to age in both men and women. This was the case irrespective of the speed of contraction in both genders (men: r = -0.797 to -0.756, all P < 0.001, women: r = -0.639 to -0.530, all P < 0.001). A significant correlation was observed between CSA of QF and peak torque during isometric knee extension in men (r = 0.827, P < 0.001) and women (r = 0.657, P < 0.001). During isometric contraction, the force/CSA exhibited a significant decrease with increasing age in men (r = -0.518, P < 0.001) but not in women (r = -0.207, NS).

CONCLUSION

These results thus suggest that muscle strength losses would be mainly due to a decline in muscle mass in both genders, whereas age-related decline in muscle function in men may also be the result of neural factors, such as muscle recruitment and/or specific tension.

The use of magnetic resonance images to investigate the influence of recruitment on the relationship between torque and cross-sectional area in human muscle

The purpose of the present study was to investigate the effect of recruitment on the relationship between peak torque and physiological cross-sectional area (PCSA) in human muscle. A group of 11 healthy men participated in this study. Isokinetic knee extension torques at seven (0, 30, 60, 120, 180, 240, and 300 degrees x s(-1)) velocities were determined. Magnetic resonance imaging (MRI) was performed to calculate PCSA of right quadriceps femoris (QF) muscle. Exercise-induced contrast shifts in spin-spin relaxation time (T2)-weighted MRI were taken at rest and immediately after repetitive knee-extension exercise and T2 of QF were calculated. The MRI pixels with T2 values more than 1 SD greater than the means at rest were considered to represent QF muscle that had contracted. The area of activated PCSA within the total in QF was expressed as percentage activated PCSA and used as an index of muscle recruitment. The PCSA correlated with peak torque at 0 degree x s(-1) (r = 0.615, P<0.05); in contrast, activated PCSA correlated with peak torque at 120 degrees x s(-1) (r = 0.603, P<0.05) and 180 degrees x s(-1) (r = 0.606, P<0.05). Additionally, there was a significant difference in correlation coefficients between the activated PCSA-peak torque relationship and the PCSA-torque relationship (P<0.05). These results suggested that muscle recruitment affects the PCSA-torque relationship.

Hereditary dominance of fast-twitch fibers in skeletal muscles and relation of thyroid hormone under physiological conditions in rats

To investigate whether muscle fiber compositions of various skeletal muscles were correlated with each other and whether muscle fiber type composition was related to the serum thyroid hormone level, fast-twitch fiber dominant rats (FFDR), which had a higher percentage of fast-twitch (FT) fibers in the deep portion of the lateral head of the gastrocnemius muscle (GAS), were compared to a control group. The FFDR group was obtained by the selective breeding for high-percentage FT fibers in the GAS, and the control group was obtained by random breeding from the same base population. The percentages of FT fibers of the GAS, soleus (SOL), vastus intermedius (VI), biceps brachii (BB), rectus abdominis (RA) and extensor digitorum longus (EDL) muscles were analyzed. The percentages of FT fibers of the GAS, SOL, VI and BB in the FFDR group were significantly higher than in the control group (p<0.05), and percent FT fibers of the GAS were significantly correlated with those of the SOL (r = 0.62, p<0.01), VI (r = 0.45, p <0.05) and BB (r = 0.43, p<0.05). On the other hand, no significant differences between FFDR and the control group and no significant correlations with the GAS were observed in percent FT fibers of the RA and EDL. The total 3,3',5-triiodo-L-thyronine (T3) level in FFDR was not significantly different from the control group and was not significantly correlated with the percentage of FT fibers. These data suggest that the percentages of FT fibers of various skeletal muscles are genetically correlated with each other, but some FT muscles are not because they might be close to the upper limits of the genetic adaptive range. In addition, percentages of FT fibers are independent of the total T3 level under physiological conditions.

New cycloartane triterpenoids from Passiflora edulis

Three cycloartane triterpenes, cyclopassifloic acids E (1), F (2), and G (3), and their saponins, cyclopassiflosides VII (4), VIII (5), IX (6), X (7), and XI (8), were isolated from the leaf and stem parts of Passiflora edulis. The structures of 1-8 were elucidated on the basis of extensive NMR experiments and by chemical methods.

Four cycloartane triterpenoids and six related saponins from Passiflora edulis

Four cycloartane triterpenes, cyclopassifloic acids A (1), B (2), C (3), and D (4), and six related saponins, cyclopassiflosides I (5), II (6), III (7), IV (8), V (9), and VI (10), were isolated from the leaves and stems of Passiflora edulis, and their structures were elucidated on the base of extensive NMR experiments and chemical methods. Cyclopassifloic acids A-D were assigned as 22(R), 24(S)-1alpha,3beta,22,24,31-pentahydroxy-24-methylcycloartan -28-oic acid; 24(S)-1alpha,3beta,24, 31-tetrahydroxy-24-methylcycloartan-28-oic acid; 20(S),24(S)-1alpha, 3beta,21,24,31-pentahydroxy-24-methylcycloartan-28-oic acid; and 22(R)-1alpha,3beta,22-trihydroxy-24-oxocycloartan-28-oic acid, respectively. Cyclopassiflosides I-VI, in turn, were established as the 28-O-beta-D-glucopyranosides of cyclopassifloic acids A-D. Finally, cyclopassiflosides III and V were demonstrated as the 28, 31-bis-O-beta-D-glucopyranosides of cyclopassifloic acids B and C, respectively. Also obtained in this investigation were the known compounds passiflorin (11) and passifloric acid (12).

Non-weight-bearing condition arrests the morphological and metabolic changes of rat soleus motoneurons during postnatal growth

Effects of non-weight-bearing (NWB) on morphological and metabolic properties of motoneurons innervating the soleus muscle, a postural muscle, were studied in young growing rats. The soma size and the activity of succinate dehydrogenase (SDH), a mitochondrial enzyme, were examined after hindlimb suspension. The hindlimb suspension began at 21 day of age and lasted for 3 week. The results were compared with 21- and 42-day-old controls. The soleus motoneurons were identified by using a fluorescent retrograde tracer, nuclear yellow. The histochemical SDH activity of soleus motoneurons was not modified during the postnatal growth and after the NWB condition. However, postnatal increases in the soma size and the total SDH activity (SDH activityxsoma size) were arrested by the NWB condition. The results indicate that the weight support activity imposed on soleus motor units would be important to postnatal increases in the soma size and the total SDH activity (i.e. mitochondria) of soleus motoneurons.

Changes in capillary luminal diameter in rat soleus muscle after hind-limb suspension

This study examined the time course change of the capillary luminal diameter and the number of capillaries in the rat soleus muscle during hind-limb suspension. Male Wistar rats were divided into 1 and 3 weeks of hind-limb suspension (HS) groups (HS-1 and HS-3). The HS groups were compared with age-matched control groups. All morphometric parameters with respect to capillary and muscle fibre cross-sectional area were determined in perfusion-fixed soleus muscles. After 1 and 3 weeks of hind-limb suspension, the mean muscle fibre cross-sectional area was significantly decreased in HS-1 (-32.0%) and HS-3 (-59.3%) compared with age-matched control groups. Despite a lower capillary-to-fibre ratio (HS-1, -19.3%; HS-3, -21.2%), the capillary density was unchanged in HS-1 and significantly increased in HS-3 compared with age-matched control groups. The mean capillary luminal diameter was significantly smaller in HS-1 (-19.9%) and HS-3 (-21.9%) than in the age-matched control groups. The capillary-to-fibre perimeter ratio which indicates the capillary surface area available for gas exchange between blood and tissue did not significantly differ between control groups and HS groups. In conclusion, the morphometrical adaptations in rat soleus with the suspension involved changes in both the capillary luminal diameter and number of capillaries, and the change in capillary surface area was proportional to the degree of muscle atrophy in HS groups.

SDH activity and cell size of tibialis anterior motoneurons and muscle fibers in SAMP6

Succinate dehydrogenase (SDH) activities and cross-sectional areas (CSAs) of tibialis anterior motoneurons and muscle fibers were determined in 20-, 40-, and 60-week-old male senescence-accelerated mice (SAMP6), and compared with those in age-matched accelerated-senescence resistant mice (SAMR1). The mean CSA of motoneurons in SAMP6 decreased at 60 weeks, primarily due to a selective loss of large (>400 microm2) motoneurons. The mean SDH activity of motoneurons with CSAs between 100 and 400 microm2 decreased in SAMP6, but not SAMR1, at 60 weeks. The mean muscle fiber SDH activities and CSAs in SAMP6 decreased at 60 weeks. There were no differences in the mean SDH activity or CSA of motoneurons or muscle fibers among 20-, 40-, and 60-week-old SAMR1. These results demonstrate that mice which have been shown to have a variety of accelerated-senescent features also have an earlier onset of age-related changes in motoneurons and the muscle fibers that they innervate when compared with age-matched accelerated-senescence resistant mice.

Muscle fibre number is a possible determinant of muscle fibre composition in rats

The purpose of the present study was to investigate whether the muscle fibre composition is related to the number of muscle fibres. To resolve this issue, we developed fast-twitch fibre dominant rats (FFDR) by selective breeding and compared the findings to those of control rats (CR) obtained by random breeding. Percentage of type I fibres of the deep portion of gastrocnemius (DG), soleus (SOL), vastus intermedius (VI), adductor longus (AL), and biceps brachii (BB) muscles in FFDR were lower than CR. Percentage of type IIB fibres in DG, VI and AL and percentage of type IIA fibres of SOL in FFDR were higher than CR. However, fibre composition of plantaris (PLAN), extensor digitorum longus (EDL), rectus abdominis (RA), diaphragm (DIA), and palmaris longus (PL) muscles in FFDR were identical with CR. Total fibre numbers on the cross-sectional area in SOL, PLAN, EDL, AL and PL were counted. Numbers of type I fibres of all those muscles in FFDR were not different from CR. Numbers of type IIA fibres of SOL and AL and of type IIB fibres of AL in FFDR were greater than CR, but there were no significant differences in the number of type IIA or type IIB fibres of PLAN, EDL or PL between the two groups. Based on these observations, it is suggested that there are pleiotropic and muscle-specific effects on muscle fibre composition. In addition, the number of type II fibres is a possible determinant of muscle fibre composition.

Age effect on expression of myosin heavy and light chain isoforms in suspended rat soleus muscle

This study was designed to test the hypothesis that myosin heavy (MHC) and light chain (MLC) plasticity resulting from hindlimb suspension (HS) is an age-dependent process. By using an electrophoretic technique, the distribution of MHC and MLC isoforms was quantitatively evaluated in the soleus muscles from 3- or 12-wk-old rats after 1-3 wk of HS treatment was maintained. In normal 12- and 15-wk-old rats, the soleus muscles contained a predominance of MHCI ( approximately 94%) with small amounts of MHCIIa, but not MHCIId or MHCIIb. The suspended muscles of adult rats were characterized by the appearance of MHCIIb and MHCIId, the latter reaching approximately 6% after 3 wk of HS treatment. In contrast to changes in MHC, HS did not induce a transition in the MLC pattern in the soleus muscles from adult rats. Compared with adult rats, in juveniles HS had a much more pronounced effect on the shift toward faster MHC and MLC isoform expression. The soleus muscles of 6-wk-old rats after 3 wk of HS were composed of 37.0% MHCI, 19.1% MHCIIa, 23.7% MHCIId, and 20.2% MHCIIb. Changes in MLC isoforms consisted of an increase in MLC1f and MLC2f concomitant with a decrease in MLC2s. These results indicate the existence of a differential effect of HS on MHC and MLC transitions that appears to be age dependent. They also suggest that the suspended soleus muscles from young rats may acquire the intrinsic contractile properties that are intermediate between those in the normal soleus and typical fast-twitch skeletal muscles.

Early phase adaptations of muscle use and strength to isokinetic training

The purpose of this study was to investigate the effect of short periods of isokinetic resistance training on muscle use and strength. Seven men trained the right quadriceps femoris muscles (QF) 9 d for 2 wk using 10 sets of 5 knee extensions each day. Isometric and isokinetic torques of QF were measured at six angular velocities. Cross-sectional areas (CSA) of QF were determined from axial images using magnetic resonance imaging (MRI). Transverse relaxation time (T2) and activated area of QF, which represented the area greater than the mean resting T2 + ISD in MR[pixels, were calculated at rest and immediately after repetitive isokinetic knee extensions based on T2-weighted MR images. Muscle fiber types, fiber area, and phosphofructokinase (PFK) activities were determined from biopsies of the vastus lateralis muscle. No changes were found in CSA of QF, muscle fiber types, fiber area, and PFK activities after the training. Isometric and isokinetic peak torques at 60-240 degrees x s(-1) and relative area of QF activated by knee extensions increased significantly after the training. These results suggest that muscle strength increases after short periods of isokinetic resistance training without muscle hypertrophy would be due to increased muscle contractile activity.

Maintenance of myoglobin concentration in human skeletal muscle after heavy resistance training

The aim of this study was to determine the effects of 8 weeks of resistance training (RT) on the myoglobin concentration ([Mb]) in human skeletal muscle, and to compare the change in the [Mb] in two different RT protocols. The two types of protocol used were interval RT (IRT) of moderate to low intensity with a high number of repetitions and a short recovery time, and repetition RT (RRT) of high intensity with a low number of repetitions and a long recovery time. A group of 11 healthy male adults voluntarily participated in this study and were divided into IRT (n = 6) and RRT (n = 5) groups. Both training protocols were carried out twice a week for 8 weeks. At the completion of the training period, the one-repetition maximal force values and isometric force were increased significantly in all the subjects, by about 38.8% and 26.0%, respectively (P < 0.01). The muscle fibre composition was unchanged by the 8 weeks of training. The muscle fibre cross-sectional areas were increased significantly by both types of training in all fibre types (I, IIa and IIb, mean + 16.1 %, P < 0.05). The [Mb] showed no significant changes at the completion of the training [IRT from 4.63 (SD 0.63) to 4.48 (SD 0.72), RRT from 4.47 (SD 0.75) to 4.24 (SD 0.80) mg x g(-1) wet tissue] despite a significant decrease in citrate synthase activity [IRT from 5.27 (SD 1.45) to 4.49 (SD 1.48), RRT from 5.33 (SD 2.09) to 4.85 (SD 1.87) micromol x min(-1) x g(-1) wet tissue; P < 0.05] observed after both protocols. These results suggested that myoglobin and mitochondria enzymes were regulated by different mechanisms in response to either type of RT. Moreover, the maintained [Mb] in hypertrophied muscle should preserve oxygen transport from capillaries to mitochondria even when diffusion distance is increased.

Changes in surface EMG parameters during static and dynamic fatiguing contractions

The effect of contraction types on muscle fiber conduction velocity (MFCV), median frequency (MDF) and mean amplitude (AMP) of surface electromyography was examined in the vastus lateralis of 19 healthy male adults. The subjects performed knee extension both statically and dynamically until they were exhausted. The static contraction was a sustained isometric extension of the knee at a joint angle of 90 degrees with 50% of the maximum voluntary contraction (MVC) load. The dynamic contraction was a repetitive isotonic extension of the knee between the angles of 90 degrees and 180 degrees with the same 50% MVC load at a frequency of 10 times per minute. MFVC during the static contraction significantly decreased during the exercise (p < 0.01). On the other hand, MFVC during the dynamic contraction did not significantly change throughout the exercise. MDF decreased and AMP increased during both types of contractions (p < 0.01). Because the blood flow within the muscle is maintained during the dynamic contraction by enhanced venous return from the contracting muscle, these results suggested that MFVC is affected by the metabolic state in the muscle and the changes in MDF cannot be explained only by that of MFVC.

Effects of exhaustive exercise on biochemical characteristics of sarcoplasmic reticulum from rat soleus muscle

This study examined the effects of acute high-intensity and moderate-intensity exercise on Ca2+-stimulated adenosine triphosphatase (ATPase) activity and the Ca2+ and ATP dependence of Ca2+-ATPase of the sarcoplasmic reticulum (SR) in the soleus muscle. The rats were run on 10% grade at 50 m min(-1) or 25 m min(-1) until fatigued (avg. time to exhaustion 2.8 and 87.7 min, respectively). The catalytic activities of SR Ca2+-ATPase were significantly depressed immediately after both types of exercise. Kinetic analyses demonstrated that the Ca2+ affinity of Ca2+-ATPase was elevated by both types of exercise adopted in the present investigation whereas the increase in the ATP affinity was brought about by only high-intensity exercise. These results suggest that exhaustive exercise may induce in slow-twitch muscle fibre the environmental changes, which adversely affect SR Ca2+-ATPase activity and can overcome the positive influence arising from the increase in the Ca2+ and/or ATP affinities of SR Ca2+-ATPase.

Detraining effects on bone mass in young male rats

The effects of exercise training and detraining on bone mass were assessed in young male Wistar rats. The rats were divided randomly into sedentary control (C) and exercise training (T) groups. The T rats were trained for 10 weeks followed by a 10-week detraining period. Training consisted of running exercise on a rodent treadmill at 35 m/min, +5-degree inclination, 60 min/day, 5 days/week. Training induced significant gain in fat-free dry weight and length of bones (femur, tibia, humerus and coxa) and bone mineral content (femur, tibia and humerus). Histological analysis at the tibial mid-shaft revealed a significant increase in total and cortical areas without a significant change in marrow area in the T group. Bone mass acquired through running exercise was retained for 10 weeks after cessation of training. These results indicate that running exercise leads to increased cortical bone associated with enhanced periosteal bone formation which is also maintained even after stopping exercise training, and suggest that training effects on the skeleton in bone mass level do not diminish immediately after cessation of training.

Changes in insulin-stimulated glucose transport and GLUT-4 protein in rat skeletal muscle after training

After running training, which increased GLUT-4 protein content in rat skeletal muscle by <40% compared with control rats, the training effect on insulin-stimulated maximal glucose transport (insulin responsiveness) in skeletal muscle was short lived (24 h). A recent study reported that GLUT-4 protein content in rat epitrochlearis muscle increased dramatically ( approximately 2-fold) after swimming training (J.-M. Ren, C. F. Semenkovich, E. A. Gulve, J. Gao, and J. O. Holloszy. J. Biol. Chem. 269, 14396-14401, 1994). Because GLUT-4 protein content is known to be closely related to skeletal muscle insulin responsiveness, we thought it possible that the training effect on insulin responsiveness may remain for >24 h after swimming training if GLUT-4 protein content decreases gradually from the relatively high level and still remains higher than control level for >24 h after swimming training. Therefore, we examined this possibility. Male Sprague-Dawley rats swam 2 h a day for 5 days with a weight equal to 2% of body mass. Approximately 18, 42, and 90 h after cessation of training, GLUT-4 protein concentration and 2-[1,2-3H]deoxy-D-glucose transport in the presence of a maximally stimulating concentration of insulin (2 mU/ml) were examined by using incubated epitrochlearis muscle preparation. Swimming training increased GLUT-4 protein concentration and insulin responsiveness by 87 and 85%, respectively, relative to age-matched controls when examined 18 h after training. Forty-two hours after training, GLUT-4 protein concentration and insulin responsiveness were still higher by 52 and 51%, respectively, in muscle from trained rats compared with control. GLUT-4 protein concentration and insulin responsiveness in trained muscle returned to sedentary control level within 90 h after training. We conclude that 1) the change in insulin responsiveness during detraining is directly related to muscle GLUT-4 protein content, and 2) consequently, the greater the increase in GLUT-4 protein content that is induced by training, the longer an effect on insulin responsiveness persists after the training.

Evaluation of Distribution Constants of Lanthanoid(III) Acetylacetonates between Sodium Dodecyl Sulfate Micelles and Water by Micellar Capillary Electrophoresis

The solubilization behavior of acetylacetonate complexes of lanthanoids(III) (Nd, Sm, Tb, and Tm) in sodium dodecyl sulfate micelles has been quantitatively evaluated by means of micellar capillary electrophoresis. From analysis of the migration times of the lanthanoid complexes, assuming incorporation of the cationic bis-acetylacetonates as well as the neutral tris-acetylacetonates into the anionic micelles, the distribution constant of each species between the micelles and water (Kmc/w) was determined. The distribution constants obtained were compared with those of the tris-acetylacetonates between heptane and water (Khep/w). The Kmc/w value of the neutral complex is smaller than that of the cationic one but much larger than the Khep/w value. The Kmc/w and Khep/w values of the neutral complex increase with increasing atomic number of the lanthanoid, whereas the opposite tendency was observed for Kmc/w of the cationic complex. Copyright 1997 Academic Press. Copyright 1997Academic Press

Adaptation of myoglobin in compensatory hypertrophied rat muscle

This study investigated the time course change of myoglobin concentration ([Mb]) in skeletal muscle during muscle hypertrophy in rats. Seven groups of Wistar rats (n = 7 per group) were examined. Compensatory hypertrophy of the plantaris muscle was induced by the bilateral ablation of the medial and lateral heads of the gastrocnemius muscle, and the effect of compensatory hypertrophy on the [Mb] of the plantaris muscle was examined at 7, 21 and 42 days post-ablation. The [Mb] expressed as mg g(-1) wet muscle weight tended to decline at 7 days post-ablation (-12.1%) and returned to the control level by 42 days post-ablation, as did the muscle protein concentration. However, the [Mb] expressed as mg g(-1) protein weight was not significantly different between the ablation and control groups throughout the experimental period. The estimated value of absolute Mb content in the whole plantaris muscle was significantly increased by 28.4% (P < 0.01) at 42 days post-ablation compared with the age-matched controls. Therefore, the longer period of compensatory activity allowed the Mb to increase in its absolute content, although the [Mb] did not exceed the level of control muscle. The capacity of facilitated oxygen diffusion and oxygen storage by Mb in the muscle cells will not change even when muscle enlargement takes place.

Effects of different intensity endurance training on the capillary network in rat skeletal muscle

Effects of low- and high-intensity endurance training on the capillary luminal diameter and number were studied morphometrically in the rat plantaris muscle. Male Wistar-Imamichi rats were divided into three groups: sedentary control group (Cont, n = 9), low-intensity (running speed of 20 m/min) training group (T-20, n = 8) and high-intensity (running speed of 40 m/min) training group (T-40, n = 7). Rats in both training groups were subjected to each treadmill running program for 60 min/day, 5 days/week for 9 weeks. After 9 weeks of training, citrate synthase activity significantly increased in T-40 compared with Cont, but did not change in T-20. All morphometric parameters with respect to capillary and muscle fiber area were determined in the perfusion-fixed plantaris muscle. The mean muscle fiber areas in both T-20 and T-40 were similar to that in Cont. The capillary-to-fiber ratios were significantly higher in T-20 (2.28 +/- 0.06) and T-40 (2.29 +/- 0.06) than in Cont (2.00 +/- 0.07). The number of capillaries with a small luminal diameter (2-4 microns) was significantly higher in T-20 than in Cont. In contrast, T-40 had a significantly higher number of capillaries with a large luminal diameter (8-10 microns) compared with Cont. This study indicates that endurance training induces changes in the capillary luminal diameter as well as capillary number, and that the adaptive response of the capillary luminal diameter to endurance training depends on the training intensity.

Denervation-induced region-specific changes in fibre types in the soleus and plantaris muscles of rats

Muscle fibre composition was compared among the proximal (25%), middle (50%) and distal (75%) regions of muscle to investigate whether denervation induces region-specific changes of fibre types in the soleus and plantaris muscles of rats. Decreases in mass were observed in both muscles after denervation. In the soleus muscle, denervation increased the percentage of type I fibres with a concomitant increase in the proportion of type IIC and IIA fibres. The extent of such transformations was greater in the proximal region than the middle and distal regions. In normal plantaris muscle, the middle region showed a higher proportion of type IIA fibres with a lower percentage of type IIB fibres reciprocally than other regions. These regional differences in fibre types were not detected in the 4-week denervated plantaris muscle. These findings suggest that denervation-induced transformations from type I to type II fibres begin in the proximal region in the soleus muscle of rats. In addition, regional differences in fibre types along the muscle length could be regulated by neuromuscular activity through normal innervation in the plantaris muscle.

Morphological adaptation of capillary network in compensatory hypertrophied rat plantaris muscle

The aim of this study was to examine the morphological adaptation of the capillary network in hypertrophied plantaris muscles by examining both capillary numbers and luminal circumferences. Hypertrophy of the plantaris muscle was induced by myectomy of the gastrocnemius muscle. This hypertrophy was characterised by increases in muscle mass and fibre cross-sectional area. All capillary parameters were determined using morphometric methods in perfusion-fixed plantaris muscle. Increased capillary-to-fibre ratio was observed in the overloaded plantaris muscle while no change was observed in the capillary luminal circumference. No differences were observed in the capillary density and the capillary-to-fibre perimeter ratio of the normal and the hypertrophied plantaris muscle. These results indicated that chronic overload-induced neocapillarization, but not enlargement of capillary luminal circumference, contributed to the prevention of decreases in the capillary-to-fibre perimeter ratio in the plantaris muscle in the hypertrophied process.

Oxidative enzyme activity and soma size in motoneurons innervating the rat slow-twitch and fast-twitch muscles after chronic activity

The effects of chronic activity induced by running training on the activity of the mitochondrial enzyme succinate dehydrogenase (SDH) and soma size in motoneurons innervating the slow-twitch soleus (SOL) and fast-twitch extensor digitorum longus (EDL) muscles were studied in rats using the retrograde neuronal tracer Nuclear Yellow. Rats were assigned to control and trained groups that were subjected to treadmill running for 10 weeks (2 h/day, 30 m/min, 5 days/week). After training, both SOL and EDL muscles showed clear adaptations (citrate synthase activity in the SOL muscle, and the fast-twitch oxidative-glycolytic fiber area of the EDL muscle increased significantly after training). The SDH activity of the motoneurons innervating both SOL and EDL muscles was unchanged by training. However, SOL motoneurons of trained rats had a significantly larger soma size and a significantly higher total SDH activity [SDH activity x soma size) than those of control. Total SDH activity was calculated to examine the absolute SDH protein content of the motoneurons. On the other hand, there was no difference in both soma size and total SDH activity of EDL motoneurons between the two groups. These data demonstrate that chronic activity has a considerably stronger impact on soma size and total oxidative enzyme activity of motoneurons innervating slow-twitch rather than fast-twitch muscles.

Expression of hybrid isomyosins in human skeletal muscle

Myosin of human skeletal muscles was analyzed by means of several electrophoretic techniques. Myosin heavy chain (HC)-IIa-and HC-IIb-based isomyosins were identified by pyrophosphate-polyacrylamide gel electrophoresis (PP-PAGE). The electrophoretic mobilities of these fast-twitch muscle isomyosins differed in the order HC-IIa triplets < HC-IIb triplets. To determine the subunit composition of myosin molecules that function in intact muscle, two-dimensional electrophoresis in which the first and second dimensions were PP-PAGE and sodium dodecyl sulfate-PAGE, respectively, was also performed. Slow-twitch muscle isomyosin contained, in addition to slow-twitch light chain (LC) and HC-I isoforms, appreciable amounts of LC-2f, HC-IIa, and HC-IIb isoforms, and fast-twitch muscle isomyosin consisted of LC-2s and HC-I isoforms as well as fast-twitch LC and HC isoforms. Without consideration of HC- and slow-twitch alkali LC heterodimers, at least 31 possible isomyosins are derived from these findings on the subunit composition of isomyosins in human skeletal muscle.

Changes in fibre types in rat soleus and plantaris muscles following hypophysectomy and compensatory overload

We investigated whether hypophysectomy could modify the change in muscle fibre types caused by compensatory overload. Male Wistar strain rats were assigned to groups of either normal control (NC), hypophysectomized control (HC), normal compensatory overloaded (NO), or hypophysectomized compensatory overloaded (HO). Compensatory overload was induced by the bilateral removal of the gastrocnemius muscle. Five weeks later, there were losses in the soleus and plantaris muscle weights as a result of hypophysectomy. Compensatory overload increased muscle weights independently of the hypophysectomy. Growth hormone and 3,5,3'-triiodothyronine levels were significantly decreased following hypophysectomy. In the soleus, hypophysectomy increased the percentage of type I fibres at the expense of type IIA fibres. Compensatory overload decreased type IIA fibres under the hypophysectomized condition. In the plantaris, the percentage of type IIC fibres was increased at the expense of both type IIA and IIB fibres following hypophysectomy. The decrease in type IIB fibres cause by compensatory overload was induced irrespective of hypophysectomy. The changes in muscle fibre types in the HO group were equal to the sum of the changes in the HC and NO groups. These results suggest that after a period of 5 weeks hypophysectomy may induced decrease in type IIA and IIB fibres in association with the lack of pituitary and thyroid hormones, and that the hypophysectomy could not modify the change in muscle fibre types caused by compensatory overload.