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Biomedical subjects

P L Willan

Publications and source records attributed to P L Willan.

17 recordsLinked to original sources
PubMed1999

Concepts of variation and normality in morphology: important issues at risk of neglect in modern undergraduate medical courses.

In anatomy, normality embraces a range of morphologies and includes those that are most common and others called variations which are less frequent but not considered abnormal. Variations ranging from subtle to remarkable affect every part of the human body. They may have important influences on predisposition to illness, symptomatology, clinical examination and investigation, and patient management including operative surgery. Recognition of variations enables clinicians to distinguish features which merit further investigation or treatment from those which do not. We believe the concepts of normality and variation should be introduced early in the medical course and that the dissecting laboratory is the ideal venue. Students who are able to examine several specimens or are privileged to dissect soon realize that each cadaver is unique. Knowledge of variations should be reinforced in several components of the medical course where physical examination, imaging investigations, surgical procedures, and autopsies are studied. Appreciation of the range of normality including variations matures as experience is gained over several years. Current trends in undergraduate courses--including reduced exposure to dissection and dissected specimens, increased use of plastic bones, models and computer-generated images, loss of experienced teachers, especially those who are medically qualified, and loss of morphological approach-- all conspire to defer the stage when students encounter variation. We are concerned that these trends will compromise the knowledge and understanding of variation required to start practicing medicine safely and competently.

Anatomy↗
PubMed1999

Profiles of applicants for junior faculty posts to teach anatomy in the UK: changing populations of candidates.

This study was undertaken to document the popularity of appointments as temporary lecturer in anatomy (TLA) at the University of Manchester during the period 1991-1998, and to profile the applicants for the posts. Data concerning 465 applicants were collated from departmental records and application forms. Prior to 1996, there were about seven applicants per post and most were men who intended to pursue surgical careers. The mean age of the applicants was 26 years, range 22-61 years. Graduates of Manchester University formed 28% of applicants, non-UK graduates 11%, and 52% possessed qualifications additional to their medical degrees. After 1996, there were fewer applicants, about three per post, who were somewhat older, mean age 30 years, range 21-52 years, and from more diverse backgrounds; 40% were non-UK graduates. The probable reasons for the decline in popularity of the appointments are explored.

Adult↗
PubMed1998

Career progress of temporary lecturers in anatomy: a surgical success story.

A questionnaire concerning career progress was sent to 159 previous holders of temporary lecturer posts in anatomy (TLAs) at the University of Manchester (UK) between 1975 and 1992. Replies were received from 123 TLAs, of whom 90% were male and 71% had achieved Fellowship(s) of a Royal College of Surgeons. Of the 86 respondents who had reached career appointments, 72% held surgical posts, 16% were in general practice, 6% were in nonsurgical hospital specialties, and 6% in nonclinical careers. The duration of training for the surgical specialties overall had been 12 years. Postgraduate diplomas and degrees had been obtained by 93% of career post holders. Most respondents (87%) had found the posts to be useful for their ongoing careers, citing improved communication skills and teaching. The positive values of temporary lecturer posts in anatomy are discussed in relation to the declining numbers of medically qualified anatomists, and the implications of changes in postgraduate surgical training in the UK are highlighted.

Anatomy↗
PubMed1995

Skeletal muscle buffer value, fibre type distribution and high intensity exercise performance in man.

Interrelationships between quadriceps femoris muscle buffer value (beta), fibre type distribution, and lactate concentration and pH following short-term high intensity exercise were examined in eighteen young healthy human volunteers. Muscle biopsy samples were taken from the lateral portion of the quadriceps femoris muscle at rest and after fatiguing dynamic or isometric exercise. Isometric exercise required the maintenance of 60% quadriceps maximum voluntary contraction, and dynamic exercise, the performance of a modified Wingate Test. The muscle buffer value displayed a positive, but non-significant correlation with the relative area of the muscle occupied by type II fibres (r = 0.42, P = 0.09). An elevated beta was associated with a lesser decrement in muscle pH during intensive exercise but did not permit the accumulation of a higher muscle lactate concentration or allow for an enhanced dynamic or isometric exercise performance. A superior performance during dynamic exercise was associated with a high concentration of muscle lactate and a low muscle pH post-exercise; in turn, each of these factors was positively dependent on the relative area of the muscle occupied by type II fibres. The converse was found for isometric exercise, where there was a tendency for an enhanced performance to be associated with a low muscle lactate and high muscle pH post-exercise. No significant relationship between the relative type II fibre area and isometric performance capacity could be established. It was concluded that the muscle buffer value is not a major limiting factor to the performance of high intensity exercise, suggesting that the involvement of intramuscular acidosis in the development of fatigue may be indirect. The most important determinant of high intensity exercise capacity appears to be the proportional area of the muscle occupied by type II fibres, where a high value provides for a superior dynamic but inferior isometric exercise performance.

Acid-Base Equilibrium↗
PubMed1994

Effects of isokinetic training of the knee extensors on high-intensity exercise performance and skeletal muscle buffering.

Twenty-three subjects isokinetically trained the right and left quadriceps femoris, three times per week for 16 weeks; one group (n = 13) trained at an angular velocity of 4.19 rad.s-1 and a second group (n = 10), at 1.05 rad.s-1. A control group (n = 10) performed no training. Isometric endurance time at 60% quadriceps maximum voluntary contraction (MVC), mean power output and work done (W) during all-out cycling, and the muscle buffer value (B) and carnosine concentration of biopsy samples from the vastus lateralis, were all assessed before and after training. The two training groups did not differ significantly from each other in their training response to any of these variables (P < 0.05). No significant difference in either 60% MVC endurance time or impulse [(endurance time x force) at 60% MVC] was observed for any group after the 16 week period (P > 0.05). However, the post-training increase (9%) in W during high-intensity cycling was greater in the training group than in the control group (P = 0.04). Neither B nor carnosine concentration showed any significant change following training (P = 0.56 and P = 0.37, respectively). It is concluded that 16 weeks of isokinetic training of the knee extensors enables subjects to do more work during high-intensity cycling. Although the precise adaptations responsible for the improved performance have yet to be identified, they are unlikely to include an increase in B.

Adolescent↗
PubMed1993

Determination of human skeletal muscle buffer value by homogenate technique: methods of measurement.

The human muscle buffer value (beta) is most frequently determined by either fixed acid titration of a homogenate ["in vitro" beta (beta vit)] or measurement of the change in lactate concentration (delta [La]) relative to the change in muscle homogenate pH after high-intensity exercise ["in vitro" beta = - delta [La]/delta pH (beta viv)]. We sought to compare beta viv, determined after isometric and dynamic exercise to exhaustion (approximately 60 s), with beta vit. Resting (R) and postexercise (E) biopsy samples were taken from vastus lateralis muscles of 43 human volunteers. Freeze-dried muscle was homogenized (30 mg/ml) in NaF (0.01 M) for the measurement of muscle pH (R and E). beta vit was determined by HCl (0.01 M) titration of the homogenate over the pH range 7.1-6.5. Muscle lactate was measured by enzymatic assay. There was no significant difference between beta viv determined after isometric (n = 35) or dynamic (n = 8) exercise to fatigue (170 vs. 168 mmol H+.kg dry muscle mass-1.pH-1, respectively; P > 0.05). Values for beta vit in the corresponding muscle samples (R) were approximately 7-8% lower (156 +/- 25 vs. 157 +/- 18 mmol H+.kg dry muscle mass-1.pH-1, respectively). There was no significant difference (P = 0.278) between the measured decline in muscle homogenate pH after exercise and the reduction in pH predicted from beta vit and delta [La], indirectly confirming the lack of any significant difference between beta viv and beta vit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Carnosine and anserine concentrations in the quadriceps femoris muscle of healthy humans.

The content of anserine and carnosine in the lateral portion of the quadriceps femoris muscle of 50 healthy, human subjects has been studied. Anserine was undetectable in all muscle samples examined. Muscle carnosine values for the group conformed to a normal distribution with a mean (SD) value of 20.0 (4.7) mmol.kg-1 of dry muscle mass. The concentration of carnosine was significantly higher in the muscle of male subjects (21.3, 4.2 mmol.kg-1 dry mass) than in females of a similar age and training status (17.5, 4.8 mmol.kg-1 dry mass) (P less than 0.005). The test-retest reliability of measures was determined on a subgroup of 17 subjects. No significant difference in mean carnosine concentration was found between the two trials [21.5 (4.0) and 22.0 (5.2) mmol.kg-1 dry muscle mass; P greater than 0.05]. The importance of carnosine as a physicochemical buffer within human muscle was examined by calculating its buffering ability over the physiological pH range. From the range of carnosine concentrations observed (7.2-30.7 mmol.kg-1 dry muscle mass), it was estimated that the dipeptide could buffer between 2.4 and 10.1 mmol H+.kg-1 dry mass over the physiological pH range 7.1-6.5, contributing, on average, approximately 7% to the total muscle buffering. This suggests that in humans, in contrast to many other species, carnosine is of only limited importance in preventing the reduction in pH observed during high intensity exercise.

Adolescent↗
PubMed1992

Effects of isokinetic training of the knee extensors on isometric strength and peak power output during cycling.

Isokinetic training of right and left quadriceps femoris was undertaken three times per week for 16 weeks. One group of subjects (n = 13) trained at an angular velocity of 4.19 rad.s-1 and a second group (n = 10) at 1.05 rad.s-1. A control group (n = 10) performed no training. Maximal voluntary contraction (MVC) of the quadriceps, and peak pedal velocity nu p,peak) and peak power output (Wpeak) during all-out cycling (against loads equivalent to 9, 10, 11, 12, 13 and 14% MVC) were assessed before and after training. The two training groups did not differ significantly from each other in their training response to any of the performance variables (P > 0.05). No significant difference in MVC was observed for any group after the 16-week period (P = 0.167). The post-training increases in average Wpeak (7%) and nu p,peak (6%) during the cycle tests were each significantly different from the control group response (P = 0.018 and P = 0.008, respectively). It is concluded that 16 weeks of isokinetic strength training of the knee extensors is able to significantly improve nu p, peak and Wpeak during spring cycling, an activity which demands considerable involvement of the trained muscle group but with its own distinct pattern of coordination.

Adult↗
PubMed1990

Morphological variations of the human vastus lateralis muscle.

Variations in the gross morphology of quadriceps femoris were assessed in 40 cadavers. An additional (fifth) head was present in about one third of the limbs. Distally, fusion between vastus lateralis and vastus intermedius varied from almost complete fusion to less than one third of the interface between the muscles. Discrete tendinous laminae arising from vastus lateralis were present in 29% of the limbs. In half the cadavers there were differences in quadriceps topography on right and left sides but there were no significant differences between muscles from male and female subjects. These findings may have important implications in clinical and microscopic studies of the quadriceps muscle.

Aged↗
PubMed1989

A quantitative study of the histochemical and morphometric characteristics of the human cricopharyngeus muscle.

Samples of human cricopharyngeus muscles obtained at postmortem were assessed for fibre type composition and fibre size. Fibre type was determined using serial cryostat sections exposed to several histochemical reactions; narrow fibre diameter and fibre area were measured from photomicrographs using a digitiser interfaced to a microcomputer. Results were compared with values from samples of vastus lateralis obtained from the same subjects. Cricopharyngeus muscle, in comparison with vastus lateralis, contained significantly more oxidative fibres but fewer glycolytic fibres and significantly more Type I fibres but fewer Type IIB. Cricopharyngeal fibres were significantly smaller than the fibres in vastus lateralis and in neither muscle were fibre sizes normally distributed. In each muscle most Type I fibres were oxidative, and the ratio of oxidative: glycolytic fibres was similar for Type IIA and IIB fibres. The fibre type proportions and fibre sizes in cricopharyngeus did not vary significantly with age or between males and females. The composition of cricopharyngeus--mostly Type I oxidative fibres and few Type II glycolytic fibres--correlated well with the functions of sustained tonicity to prevent aerophagia and occasional forceful contraction during deglutition.

Adolescent↗
PubMed1984

Variability of histochemical and morphometric data from needle biopsy specimens of human quadriceps femoris muscle.

Duplicate needle biopsies from the lateral portion of quadriceps femoris muscle from 20 young, healthy males were investigated morphometrically and histochemically. Mean results showed both the size and occurrence of the three main fibre types present to be similar to values obtained from a survey of the literature. However, considerable variations in the proportions of fibre types (coefficients of variation 30-40%) and significant (P less than 0.001) differences in fibre size between individuals were common. Within individuals, comparisons of samples taken at a reference site in the right thigh with samples obtained from deeper, more proximal or contralateral sites also often showed significant differences in fibre size. These results suggest caution is necessary when interpreting apparent changes in such values derived from subsequent biopsies of individuals.

Adenosine Triphosphatases↗
PubMed1978

A study of potential Olympic swimmers. Part 2. Changes due to three months intensive training.

Anthropometric and physiological measurements were recorded for a group of exceptional young swimmers undergoing an intensive training programme over 3 months. The observed changes are presented and are discussed in relation to the training undertaken, and are compared with expected changes due to normal growth. Some of the physiological parameters measured showed marked changes: average physical work capacity decreased significantly, while the physical fitness index improved. Many of the anthropometric changes were small, but a significant increase in lean body mass occurred in both boys and girls, and in both groups the average weight gain was greater than that expected. In individuals subjected to rigorous training significant changes in anthropometric and physiological parameters over and above the expected changes due to normal growth and development occur relatively quickly within a period of 3 months.

Adolescent↗