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Biomedical subjects

D Sale

Publications and source records attributed to D Sale.

13 recordsLinked to original sources
PubMed2001

BHRF1 is highly conserved in primate virus analogues of Epstein-Barr virus.

The Epstein-Barr virus (EBV) protein BHRF1 (BamHI rightward reading frame 1) was the first viral member of the Bcl-2 family of apoptosis-regulating proteins described. In vitro studies imply that BHRF1 is dispensable for virus-induced cellular transformation and virus replication. However, in contrast to several essential viral genes that show divergence outwith their functional domains, sequence data from a wide range of EBV isolates show there is striking conservation of the BHRF1 gene. Contrary to the in vitro studies, the high degree of conservation hints at a more important role for BHRF1. Analogous viruses are endemic in each of the higher primate species. Whilst their genome organisation is colinear, limited sequence analysis indicates that the viruses have diverged significantly and that only important functional domains of proteins are likely to be conserved. We have isolated the BHRF1 equivalents from the viruses which infect chimpanzees (Herpesvirus pan) and baboons (Herpesvirus papio) and find that they are highly homologous in both species, strengthening the hypothesis that BHRF1 plays a significant, evolutionarily conserved function in vivo and that changes to the protein are not well tolerated.

Amino Acid Sequence↗
PubMed2000

Making an impact.

Explore the source record for details and available documents.

Clinical Competence↗
PubMed1989

Voluntary and electrically evoked strength characteristics of obese and nonobese preadolescent boys.

Overweight and obese children demonstrate inferior motor performance for strength- and power-related activities requiring support or lifting of body weight. Our purpose here was to determine whether the inferior performance could be attributed to a lower strength to muscle area ratio in the obese. Eleven nonobese (16.6% fat) and 13 obese (35.5% fat) boys (9-13 years old) volunteered for the study. Peak torque was measured during voluntary isometric and isokinetic elbow flexion and knee extension at four joint angles and four velocities, respectively. The contractile properties, twitch torque, time to peak torque, and half-relaxation time were evoked for the elbow flexors by percutaneous stimulation. Elbow flexor and knee extensor cross-sectional areas (CSA) were determined by computed axial tomography taken at the mid-upper arm and mid-thigh, respectively. Isometric and isokinetic elbow flexion and knee extension strength normalized for body weight were significantly (p less than 0.05) higher in the nonobese compared to the obese boys. There were no significant (p greater than 0.05) differences, however, between groups for elbow flexor and knee extensor CSA or for absolute and relative (normalized for muscle CSA or the product of muscle CSA and height, the latter accounting for differences in moment arm length) isometric, isokinetic, or evoked twitch torque for elbow flexion or knee extension. Likewise, there were no differences between groups for the time-related contractile properties, time to peak torque, or half-relaxation time. These findings suggest that there is no difference in the intrinsic strength or contractile properties of the elbow flexor and knee extensor muscles between obese and nonobese pre-adolescent boys and that other factors, such as the handicapping effect of excess fat mass, probably account for the reduced motor performance of the obese child.

Analysis of Variance↗
PubMed1986

Endurance capacity of untrained males and females in isometric and dynamic muscular contractions.

The capacity to perform isometric and dynamic muscle contractions at different forces has been measured in two separate groups of subjects: 25 men and 25 women performed sustained isometric contractions of the knee-extensor muscles of their stronger leg to fatigue, at forces corresponding to 80%, 50% and 20% of the maximum voluntary force of contraction (MVC). The second experimental model involved a bilateral elbow-flexion weight lifting exercise. Eleven women and 12 men performed repetitions at loads corresponding to 90%, 80%, 70%, 60% and 50% of maximum load (1RM), at a rate of 10 X min-1 to the point of fatigue. Males were stronger (p less than 0.001) than females in both the static (675 +/- 120 N vs 458 +/- 80 N; mean +/- SD) and dynamic (409 +/- 90 N vs 190 +/- 33 N) contractions. Isometric endurance time of the males at a force corresponding to 20% of MVC was less than that of the females (180 +/- 51 s vs 252 +/- 56 s; p less than 0.001) but there was no difference between the sexes at 50% or 80% of MVC. Similarly, when the sexes were compared using dynamic elbow-flexion exercise, the female subjects were able to perform a greater number of repetitions than males at loads of 50% (p less than 0.005), 60% (p less than 0.001) and 70% (p less than 0.025) of 1RM, but there was no difference between the sexes at loads of 80% or 90% of 1RM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Influence of joint position on ankle plantarflexion in humans.

The contractile properties of the triceps surae (medial and lateral gastrocnemii and soleus) have been studied in humans. In comparison with most other human muscles, the triceps complex had a slow twitch (mean contraction and half-relaxation times 112.4 +/- 11.1 and 99.6 +/- 14.4 ms, respectively) and a low tetanus fusion frequency (60 Hz). Stretching the muscle caused both the contraction and half-relaxation times to become longer. With the knee bent, the optimum length for torque development corresponded to almost full dorsiflexion of the ankle. Similar results were obtained with the knee extended. The optimum position of the ankle differed considerably from the position of the joint when the leg was at rest. Although the position of the ankle joint affected electromyographic (EMG) activity recorded during maximal voluntary contraction, there was little change in the EMG-to-M wave ratio.

Adult↗
PubMed1982

Physiology of weight-lifting exercise.

This review describes the major features of skeletal muscle adaptation to weight-lifting exercise. Changes in contraction time, fiber size, and possibly fiber number may result in response to prolonged weight-training. Effective strength-training programs, both for athletics and rehabilitation, require recognition of the concept of "specificity of training," realization of the tendency of human skeletal muscle to adapt differently to different forms of physiologic stress.

Humans↗
PubMed1981

Influence of joint position on ankle dorsiflexion in humans.

A method is described for investigating the contractile properties of the dorsiflexor muscles of the ankle. With the joint in the midposition the tibialis anterior was found to contribute less than half of the maximum voluntary torque, the remainder presumably being provided by the long extensors of the toes. The mean contraction and half-relaxation times of tibialis anterior muscles in healthy young men were 81.2 +/- 7.4 (SD) ms and 83.6 +/- 17.2 ms, respectively. When the tibialis anterior was stretched, the twitch became slower and more complete fusion of the contractions occurred during tetanic stimulation at low frequencies. Stimulation of tibialis anterior at 30 and 40 Hz disclosed that the optimum length of the muscle corresponded to about 10 degrees of plantarflexion. Maximum voluntary torque was also developed at 10 degrees of plantarflexion and decreased sharply as the ankle was dorsiflex beyond 5 degrees. The position assumed by the ankle joint at rest depended on whether the subject was sitting, standing, or lying, but was always greater, in the plantarflexed direction, than the "optimum" position for torque development. At low rates of stimulation the torque continued to increase throughout the full range of plantarflexion, probably because of the elasticity of the tendon. During maximum effort motoneuronal excitability did not appear to be influenced significantly by changes in joint angle.

Adult↗
PubMed1981

Continuous vs. interval training: a review for the athlete and the coach.

Both interval and continuous training are necessary in order to maximize the endurance athlete's potential for competition. Continuous submaximal training exerts its greatest effect upon the oxygen transport system of the body, while high intensity endurance-interval training exerts its greatest effect on the structural and biochemical properties of the muscle. The physiological basis for both forms of training is discussed and recommendations are made for year-round training and training to elevate the anaerobic threshold.

Anaerobiosis↗
PubMed1976

The glycerylphosphorylcholine content of the rat epididymis after injecting alpha-chlorohydrin and ligating the vasa efferentia.

The concentration of GPC in the 4 segments (initial segment, caput, corpus and cauda) of the rat epididymis was examined at various times (4 hours. 2, 5, 10 and 20 days) following injection of a lesion-forming dose (90 mg/kg body weight) of alpha-chlorohydrin and bilateral ligation of the vasa efferentia. There was a reduction in the overall GPC concentration of the epididymis 2 days after both treatments and a further decrease until 20 days when a slight increase occurred. It is suggested that a lesion-forming dose of alpha-chlorohydrin, like ligation of the vasa efferentia, could inhibit the synthesis and/or release of GPC within the epididymis by blocking off androgen supply in the testicular fluid.

Animals↗