Radiologic study of the accuracy of a tibial intramedullary cutting guide for knee arthroplasty

Twenty-one caucasian, adult cadaveric tibiae were prepared as for knee arthroplasty using an intramedullary cutting guide. The instrumentation was used to produce slots in the proximal tibia into which Kirschner wires were placed as radio-opaque markers for subsequent anteroposterior and lateral radiographs. The anatomic axis of the tibia and lines perpendicular to the wire markers were drawn on the radiographs and the angle between the two lines was measured to assess the accuracy of the cuts. Seventy-one percent of the tibial cuts were found to be within 2 degrees of the anatomic axis on the anteroposterior radiograph (mean, 2.1 degrees), while on the lateral radiograph, 81% of the cuts were within 2 degrees (mean, 1.8 degrees). There was a significant tendency to position the bone cuts in varus (P < .05), although this did not correlate with varus or valgus deformity of the bones. There was no consistent tendency to anterior or posterior tilt on the lateral radiograph (P > .05). The results compare favorably with those obtained from a specialist unit using an extramedullary alignment system. The authors conclude that the tibial intramedullary guide can lead to preparation of the proximal tibia for knee arthroplasty as accurately as the conventional extramedullary system.

Fractures of the distal femur in the elderly treated with a carbon fibre supracondylar plate

The use of a contoured supracondylar carbon fibre plate in 22 patients with a fracture of the lower femur is reported. The patients were all elderly (mean age 80.6 years) and three patients in the study died of unrelated medical causes. Of the 19 surviving patients, in 17 the fracture united (89 per cent). The supracondylar plate was technically simple to use and the authors feel that it represents a significant advantage over existing implants for this difficult fracture.

Distribution of myomodulin-like immunoreactivity in the adult and developing ventral nervous system of the locust Schistocerca gregaria

The distribution of myomodulin-like immunoreactivity in the ventral nervous system of an insect, the locust Schistocerca gregaria, both in the adult and during development, is described. The results suggest the presence of a novel modulatory system in insects which uses myomodulin-like neuropeptides. The study also indicates that the myomodulins, which were first identified in mollusks, may represent another interphyletic family of neuropeptides. In the suboesophageal ganglion, immunoreactive cells occur in five groups. The processes from the two anterior ventral midline groups of cells project to the corpora allata via nervi corpora allata II. Thus myomodulin-like neuropeptides may be involved in the control of the release of juvenile hormone from the corpora allata. The thoracic ganglia contain three groups of immunoreactive cells, including a bilaterally symmetrical group of 12-15 posterior lateral cells, which project to the median nerve and its neurohaemal organs, suggesting a possible neurohaemal role for myomodulin-like peptides. Each thoracic neuromere also contains a single, intensely stained, dorsal unpaired median (DUM) cell that may correspond to the so-called H cell. In the abdominal ganglia, the staining shows sexual dimorphism, both in terms of the number of dorsal and ventral midline cells stained and in terms of the distribution of their immunoreactive processes. Myomodulin-like immunoreactivity is one of the earliest neurotransmitter/neurohormone phenotypes detectable during the development of the locust nervous system. It first appears in the single DUM cells in each of the thoracic neuromeres at 50% development, and the complete adult pattern of staining is present at 85-90% of development.

The effects of myomodulin and structurally related neuropeptides on skeletal neuromuscular transmission in the locust

1. The modulatory actions of myomodulin A on tension generated in the extensortibiae muscle of the locust hindleg by stimulation of the slow excitatory motoneurone (SETi) depend upon the frequency of stimulation. Myomodulin A has no consistent effect on the tension induced by the fast extensor motoneurone (FETi) or upon the myogenic rhythm present in the extensor. The effects of a range of structurally related neuropeptides have also been assessed. 2. At low frequencies of SETi stimulation (1 Hz and below), the predominant modulatory effects are increases in the amplitude, contraction rate and relaxation rate of twitch tension. At higher frequencies, where twitches summate but tetanus is incomplete (up to 20 Hz), these effects are superimposed upon an increase of maintained tension. 3. The modulatory actions of myomodulin-like peptides show some similarities to and some differences from the modulatory actions of octopamine, proctolin and FMRFamide-like neuropeptides in this preparation, but are likely to be mediated via a distinct set of receptors. 4. The results of the present study, taken together with the localization of myomodulin-like immunoreactivity in specific sets of neurones in the locust nervous system, suggest the presence of a novel modulatory system in insects that uses myomodulin-like neuropeptides. It also indicates that myomodulins, which were first identified in molluscs, may represent another interphyletic family of neuropeptides.

Agonist-specific coupling of a cloned Drosophila octopamine/tyramine receptor to multiple second messenger systems

A cloned seven transmembrane-spanning Drosophila octopamine/tyramine receptor, permanently expressed in a Chinese hamster ovary cell line, both inhibits adenylate cyclase activity and leads to the elevation of intracellular Ca2+ levels by separate G-protein-coupled pathways. Agonists of this receptor (octopamine and tyramine), differing by only a single hydroxyl group in their side chain, may be capable of differentially coupling it to different second messenger systems. Thus, a single receptor may have a different pharmacological profile depending on which second messenger system is used to assay its efficacy.

Biological activity and receptor binding properties of some analogues of pQDPFLRFamide

To investigate the role of the N-terminal region of the heptapeptide FMRFamide-like peptide, pQDPFLRFamide, three analogues were synthesized. The analogues [pQNPFLRFamide, pQDAibFLRFamide (Aib = aminoisobutyric acid) and pQDGFLRFamide] contained modifications at amino acid residues 2 and 3, which we believed might be critical for maintaining the bioactive conformation of the heptapeptide. The analogues were tested for their ability to bind to receptors in membranes from Helix aspersa circumoesophageal ganglia and for their biological effects on the isolated Helix heart, the Helix tentacle retractor muscle, and extensor-tibiae neuromuscular preparation of the locust. Schistocerca gregaria. The substitution of Asn for Asp2 and that of Aib for Pro3 were conservative with respect to retention of heptapeptide-like biological activity, whereas the substitution of Gly for Pro3 significantly improved the binding affinity of the peptide for the FMRFamide receptors and conferred on the peptide some characteristic FMRFamide-like biological activity. Thus, pQDPFLRFamide bioactivity may depend on a bent conformation in solution.

Octopamine receptor subtypes and their modes of action

Octopamine receptor subclasses were first proposed to explain differences in the pharmacological profiles of a range of physiological responses to octopamine obtained in the extensor-tibiae neuromuscular preparation of the locust. Thus, OCTOPAMINE1 receptors which inhibit an endogenous myogenic rhythm, increase intracellular calcium levels. Also OCTOPAMINE2 receptors which modulate neuromuscular transmission in this preparation, increase the level of adenylate cyclase activity. The current status of this classification is reviewed by examining the pharmacology of responses to octopamine in a range of preparations. It is concluded that the distinction between OCTOPAMINE1 and OCTOPAMINE2 receptor types is still valid, but that OCTOPAMINE2 receptors exhibit some tissue specific variations. Studies on a cloned Drosophila octopamine/tyramine (phentolamine) receptor are discussed and illustrate many of the difficulties presently encountered in making a definitive classification of octopamine receptors. These include the possibilities that single receptors may activate multiple second messenger systems and that different agonists may differentially couple the same receptor to different second messenger systems.

The Seidel humeral locking nail: an anatomical study of the complications from locking screws

The Seidel locking nail was inserted into the humeri of 20 cadavers. Subsequent dissection showed that the proximal locking screws had damaged the circumflex nerve or biceps tendon in eight of the cases.

Laboratory comparison of the cannulated Herbert bone screw with ASIF cancellous lag screws

The compression produced by and the resistance to pullout of the 6.5 mm cannulated Herbert screw were compared with those of ASIF headed screws. The latter were tested with and without washers and in the following sizes: 4.5 mm cortical, 6.5 mm cancellous with a 16 mm threaded segment, and 6.5 mm cancellous with a 32 mm threaded segment. Polyurethane foam was used as a substitute for cancellous bone and ASIF artificial bone for corticocancellous bone. The compression produced by a cancellous lag screw with a washer was significantly greater than that produced by a Herbert screw of equivalent size (p < 0.05). When the screws were tested using the corticocancellous composite the ASIF cancellous screw without a washer produced significantly greater compression (p < 0.05); when used with a washer the difference was highly significant (p < 0.001). The dual pitch Herbert screw is not appropriate for the management of fractures in which compression is of greater importance than the need to avoid prominence of the screw head.

Molecular studies on insect octopamine receptors

Octopamine receptors are widely distributed in the insect nervous system and carry out a range of functions equivalent to the adrenergic receptors of the vertebrate sympathetic nervous system. Molecular studies on insect octopamine receptors have concentrated upon molecular pharmacological approaches to identify the particular subtype of octopamine receptor mediating its effects in a particular tissue and on the modes of action of the receptors in a particular tissue. Molecular biological approaches are now being pursued to define the structure of the octopamine receptor. Recent findings in this area will be reviewed, along with promising approaches for future molecular studies on insect octopamine receptors.

N-methyl-D-aspartate (NMDA) and non-NMDA (metabotropic) type glutamate receptors modulate the membrane potential of the Schwann cell of the squid giant nerve fibre

L-Glutamate application can produce three different responses in the membrane potential of the Schwann cell of the tropical squid, Sepioteuthis sepioidea, which appear to be mediated by three pharmacologically distinct classes of receptor. A class of non-NMDA-type receptors, with some similarities to metabotropic glutamate receptors, mediates the development of a rapid and long-lasting hyperpolarization. Two pharmacologically distinct classes of NMDA-type receptor are present. One mediates the development of a slow depolarization accompanied by a long-lasting change in responsiveness of the Schwann cell. The second produces rapid depolarizing responses during the period of this changed responsiveness. All three types of receptor can be activated by dipeptides containing excitatory amino acids.

The effect of a glutamate uptake inhibitor on axon-Schwann cell signalling in the squid giant nerve fibre

The glutamate uptake blocker p-chloromercuriphenylsulphonic acid (PCMS) (100 mumol l-1) does not block any of the membrane potential changes induced by the application of L-glutamate to the adaxonal Schwann cells of the giant axon of the tropical squid Sepioteuthis sepioidea. This indicates that these potential changes are not due to the activation of an electrogenic glutamate uptake system and supports the idea that they are due to the activation of specific glutamate receptors. The presence of PCMS (100 mumol l-1) reduces the activity of the glutamate uptake system sufficiently for the extracellular level of axonally released glutamate to exceed the threshold for the activation of the NMDA-type glutamate receptors in this preparation.

Recurrent dislocation of the hip in adult paraplegics

Recurrent dislocation of the hip is rare and has not previously been reported in adult paraplegics. This paper describes 3 cases. In one patient it was spontaneous, occurring 16 years after the original injury and was associated with a flexion-adduction contracture of the hip and a shallow acetabulum. One case occurred after minor trauma in a patient who experienced flexion-adduction spasms of the hip. In the third patient the condition was secondary to posterior acetabular deficiency following a conservatively treated fracture dislocation. All 3 patients experienced symptoms of disabling autonomic dysreflexia during the episodes of dislocation. The importance of recognising and adequately treating hip injuries in patients presenting with paraplegia secondary to spinal cord injury is stressed. In patients with spastic paraplegia presenting with recurrent dislocation of the hip, operative treatment combining a soft tissue repair and a bone block to augment the acetabulum is recommended.

Mood states and minor illness

Mood and health reports from 65 administrative and clerical staff were obtained daily over a period of several weeks. Three mood factors emerged from the aggregated data which appear to be most suitably labelled: happiness, tense depression and hostile depression. Subjects high on hostile depression suffered more from colds. Subjects scoring highly on tense depressed mood reported more insomnia, head and neck aches. The results, especially in regard to hostile depression, are discussed in a wider context, including possible overlap with core affective aspects of the well-known Type A coronary risk construct. Finally, psychoimmunological interpretations of the link between hostile depression and vulnerability to colds are considered.

The innervation of the closer muscle of the mesothoracic spiracle of the locust

The closer muscle of the mesothoracic spiracle of the locust, Schistocerca gregaria is innervated by two excitatory motoneurones and also by processes of a peripherally located neurosecretory cell. Within the muscle, ultrastructural studies show the presence of two types of excitatory nerve terminal which differ in the content of dense cored vesicles and in their distribution. The ventral segment of the muscle is innervated predominantly by terminals with small clear vesicles and only an occasional dense-cored vesicle. The central part of the muscle is innervated predominantly by terminals with small clear vesicles and larger numbers of dense-cored vesicles. The dorsal segment of the muscle is innervated exclusively by a neurosecretory type innervation. The small neurohaemal organ of the median nerve close to the spiracle muscle is immunoreactive to an antibody raised against bovine pancreatic polypeptide but no immunoreactive processes enter the muscle itself. The muscle possesses specific octopaminergic receptors that increase cyclic AMP levels and the possibility that the neurosecretory input to the muscle is provided by either a central or peripheral octopamine containing neurone is discussed.

Life-events and mood as predictors of the common cold

One hundred subjects volunteered to take part in a 'diary-type' study in which they were to check, at the end of each day, a variety of items dealing with events, mood states and health. A subsample was selected who had both provided several weeks of data and had, during that time, suffered at least one common cold episode. A lagged relationship between events and the onset of cold episodes was found. Desirable events ('uplifts') were found to decrease significantly in frequency during a period commencing four days prior to cold onset. There was a less significant tendency for the number of undesirable events ('hassles') to rise during this same period. Subjects' ratings also indicated that they had been feeling more angry, tense and sceptical during this period. It is argued that the lagged relationship, the use of subjects as their own controls, and the partly replicatory nature of the study, give strong support to psycho-immunological hypotheses concerning links between life-events and illness. Individual item analysis suggests that fluctuations in perceived intimacy, social support and self-esteem may be important mediators of the effects.