Long-lasting conditioning of the human soleus H reflex following quadriceps tendon tap

Percussion of the quadriceps tendon was used to test the hypothesis that knee extensor muscle spindle discharge initiates down-regulation of the gain of the soleus H reflex. Seven subjects participated. Soleus H reflex magnitude was observed for up to 15 s, following conditioning tendon taps of 60 N or 80 N force and 10 ms duration, with the knee at 60 degrees or 90 degrees of flexion. The tap elicited quadriceps stretch reflexes in four subjects, with a mean latency of 42 ms. The major component of the conditioning of the soleus H reflex was significant attenuation of magnitude by 30-90% of controls, starting as early as 36 ms post-percussion and lasting as long as 3-8 s. The attenuation of reflex magnitude was evident, whichever combination of duration and force of tap was used. Preceding and/or following this inhibition, there was mild facilitation. Static stretch of quadriceps also significantly reduced soleus H reflex magnitude. These results support the spindle receptor origin for the gain attenuation seen during movement. The time course of the gain attenuation suggests a spinal route, by which the spindle discharge of the heteronymous extensor muscles initiates presynaptic inhibition of transmission through the reflex pathway.

Neonatal onset of medium-chain acyl-coenzyme A dehydrogenase deficiency with confusing biochemical features

A female neonate was seen because of shock, ketosis, and undetectable blood glucose. Initial urinary findings indicated the possibility of a defect of fatty acid beta-oxidation; subsequent studies showed that she had medium-chain acyl-coenzyme. A dehydrogenase deficiency. This case highlights the fact that the initial symptoms may occur in the first few days of life, and that the presence of ketosis does not exclude the possibility of a fatty acid oxidation defect; the profiles of urinary organic acids and acylglycines may not be characteristic at that time.

The quiet revolution

The IHSM's day conference threw a wide spotlight on 'alternative settings for acute care'. The occasion provided a powerful and unifying commentary on a number of trends discernible in most of the specialties examined in the Medicine for Managers series.

Rheumatology

Arthritis disables more people than all other diseases and injuries put together. Given the high cost of some of the techniques used for rheumatoid arthritis, the long-term nature of the disease and the growth in demand, it is increasingly important to pose and answer questions of cost effectiveness and priority-important to clinician and manager alike.

Managing for health gain

The concept of health gain is growing in the NHS; The Health of the Nation is the first national strategy to set targets for health gain. The initiative holds implications for change for NHS managers in the way in which they perceive their task and the way in which they manage.

Plastic surgery

Plastic surgery is all too often thought of as an indulgence of the rich and famous with little attention paid to the repair of bodies and limbs disfigured or deformed by accident or illness. Surgeons look to management to address those issues that create an insecure base for planning the service and for its organisation nationwide.

Palliative care

Palliative care may not seem the highest of priorities; it is sometimes thought of as a 'luxury' to be paid for privately while the NHS picks up the 'public' cost of acute medicine. But anyone who has witnessed or experienced the work of palliative care teams would be dissuaded from these views.

Geriatric medicine

Old age never harmed anyone - but the problems that may arise in the elderly of multiple illnesses, social isolation and poverty conspire to present clinicians and managers with a challenge: an increasing challenge, as the number of people over the age of 85 by the year 2000 will be in the order of a million.

Psychiatry of old age

Some 25% of those over 80 suffer from dementia -- just one of the mental health problems that affect elderly people. Their care is compounded by physical difficulties and ill health and, often, by the lack of relatives to assist in their care.

General practice

Medicine is developing at an extraordinary rate in all clinical specialties, the pace largely driven by science and technology. General practice is developing professionally at a similar pace, but in addition is experiencing a huge change in the management of primary care, generated by the engine of policy and organisational change in the NHS.

Anaesthesia

Anaesthesia is, perhaps, the single greatest advance in medical history. Yet even today there are uncertainties about the patient's depth of sleep and the efficacy of some techniques. Cost and quality are issues that managers and anaesthetists must tackle together.

Cardiovascular disease

A figure between 550 pounds and 960 pounds is the estimated cost of buying one quality adjusted life year by screening for and preventing development of coronary heart disease risk factors. So what is it that is stopping the prevention of 180,000 deaths each year?

Child health

Current provision for children's health involves many different professions in many different locations. Managers must find local solutions to improve the organisation of services which will lead to better and more coordinated health care.

Minimally invasive therapy

Minimally invasive therapy is a new and important development in medicine. With minimal disruption to the patient's body or way of life, outcomes are at least as effective and procedures are safer than conventional surgery. But there are clear implications for management on costs, and organisational and strategic issues.

Day surgery

Costing half as much as inpatient treatment, with good results and advantages to patients, day surgery might be expected to be more widespread than it is. Purchasers may be those who push for more by specifying targets for day surgery for certain procedures. How can managers respond?

A strain-gauge study of the effect of external fixation on the canine tibia

Electrical resistance rosette strain gauges bonded directly to the surface of the midshaft of the normal canine tibia were utilized to study the effect of the AO external skeletal fixator on the magnitude and orientation of the peak strain values recorded during locomotion. The application of the fixator in a single lateral bar configuration resulted in a significant decrease in surface bone strain magnitude but in only minor changes in the orientation of those strains. However, in only one of three dogs tested did the addition of a second external connecting bar result in significant further decreases in bone strain.

A technique for electrically induced perturbation of rhythmic leg movement

The paper describes electrical circuitry which replaces a mechanical brake, for perturbation of the contractile load of the legs during pedalling. The turning flywheel of an ergometer is connected to an alternator, with the electrical load provided by a power resistor connected across the output terminals. A 12-V battery provides the field current. Through variable resistors the field current is altered under microprocessor control, providing different steady-state loads when pedalling and also sudden transient changes of load. The point of change in load in the movement cycle can be accurately selected. The ergometer is instrumented for accurate measurement of pedal crank position, crank angular velocity and reaction force at the foot, to provide a physical description of the evoked steady states and transients, using microprocessor controlled sampling. The results show that the technique has application to the study of the range of reflex responses within a movement cycle and also to the more complex restoration of a movement pattern over a number of cycles. It is applicable to investigation of normal and diseased states.

Practical preparation and deblocking conditions for N-alpha-(2-(p-biphenylyl)-2-propyloxycarbonyl)-amino acid (N-a-Bpoc-Xxx-OH) derivatives

Reproducible preparations are given for salts of the following L-amino acid derivatives: Bpoc-Ala-OH, Bpoc-Arg(Mtr)-OH, Bpoc-Asn-OH, Bpoc-Asp(OtBu)-OH, Bpoc-Cys(Acm)-OH, Bpoc-Cys(S-tBu)-OH, Bpoc-Gln-OH, Bpoc-Glu(OtBu)-OH, Bpoc-Gly-OH, Bpoc-Ile-OH, Bpoc-Leu-OH, N-alpha-Bpoc-Lys(epsilon-Boc)-OH, Bpoc-Met-OH, Bpoc-Phe-OH, Bpoc-Pro-OH, Bpoc-Ser(OtBu)-OH, Bpoc-Thr(OtBu)-OH, Bpoc-Tyr-OH, Bpoc-Val-OH. A study of the deblocking of N-alpha-Bpoc peptides in dichloromethane containing 0.5% trifluoroacetic acid revealed that a rapid equilbrium is established between the first-formed monomeric alkene 2-p-biphenylylpropene and the hindered dimer 2,4-bis(p-biphenylyl)-4-methyl-1-pentene. Thioethers were found to be inefficient carbocation scavengers for the deblocking reaction. The most efficient scavengers were found to be thiophenol and benzyl mercaptan, and the following approximate reactivity order was established: benzyl mercaptan approximately thiophenol greater than indole much greater than 1,3-dimethoxybenzene approximately resorcinol greater than 1,3,5-trimethoxybenzene approximately dimethyl sulfide approximately thioanisole.

Heat exposure-induced changes in motor outflow component of reaction time

Conduction velocity, absolute refractory period, and subnormal conduction period measures of the right ulnar motor nerve were obtained during a simple reaction time task. 6 young, healthy, right-arm dominant male subjects were tested following 30 min. exposure in ambient (20 degrees C) and hot (36 degrees C) room air conditions. Motor and premotor components of fractionated reaction time were tested on the same arm. Oral, right forearm skin and a four-site mean skin temperature were monitored. During heat exposure, forearm skin temperature increased 4.7 degrees C and mean skin temperature 2.9 degrees C. Oral temperature did not alter. Conduction velocity increased 11.4%, absolute refractory period decreased 22.7%, and subnormal conduction period decreased 14.1% in the hot condition. Concomitantly, a 5.2% increase in premotor reaction time and 12.2% decrease in motor reaction time were observed. Total RT did not alter significantly. It was concluded that different component parts of reaction time were differentially influenced by exposure to heat.

Patient management problems. Issues of validity

Patient management problems (PMP) are being used in medical examinations with increasing frequency despite evidence which throws doubt on their validity as measures of clinical competence. This study investigated the construct validity of a PMP constructed in both written and interview formats. Each test was administered to groups of students of different seniorities and to two groups of doctors, interns and post-interns. The pattern of scores for the different groups was not that expected of a valid test of competence. The most competent groups (the post-interns) generally scored less well on the calculated indices than the senior students and interns. These findings were similar for both formats of the test so cueing was not thought to be the major factor. It appears that the scoring system is at fault. A comparison of performance on the written and interview (uncued) formats showed that many more options were chosen by all groups tested on the written PMP. It was concluded that written PMPs cannot yet be regarded as a valid simulation of clinical performance. Although content validity is high this does not appear to be so for construct validity or concurrent validity.