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Biomedical subjects

J K Webb

Publications and source records attributed to J K Webb.

At least 73 records · Page 4Linked to original sources
PubMed1995

Antinociceptive activity of the tachykinin NK1 receptor antagonist, CP-99,994, in conscious gerbils.

1. The ability of CP-99,994, and its less active enantiomer, CP-100,263, to inhibit spontaneous behaviours and hyperalgesia induced by central infusion of the NK1 receptor agonist, GR73632 or intraplantar injection of formalin was investigated in rats and gerbils. 2. GR73632 (3 pmol, i.c.v.)-induced foot tapping in gerbils was dose-dependently inhibited by CP-99,994 (0.1-1 mg kg-1, s.c.), but not by CP-100,263 (10 mg kg-1, s.c.) using pretreatment times up to 60 min. The centrally active dose-range for CP-99,994 was increased to 1-10 mg kg-1 s.c. with a higher challenge dose of GR73632 (30 pmol, i.c.v.). 3. In gerbils, intrathecal (i.t.) injection of GR73632 (30 pmol) elicited behaviours (licking, foot tapping or flinching and face washing) which closely resembled, but which was less specifically localized than, behaviours seen in animals injected with formalin (0.1-5%) into one hindpaw. 4. In rats, CP-100,263, but not CP-99,994 (up to 30 mg kg-1), inhibited the early phase response to intraplantar injection of 5% formalin (ID50 = 13.9 mg kg-1). The late phase was inhibited by both compounds (ID50 values 36.3 and 20.9 mg kg-1, respectively). In gerbils, there was marginal evidence for enantioselective inhibition of the early phase induced by formalin (2%). The ID50 values were 6.2 mg kg-1 for CP-99,994 and 13.4 mg kg-1 for CP-100,263. 5. Intrathecal injection of GR73632 (30 pmol) caused thermal hyperalgesia in igerbils which was inhibited enantioselectively by s.c. administration of CP-99,994 (ID50= 2.46 mg kg-1), but not by CP-100,263 (30 mg kg-1).6. In gerbils, intraplantar injection of formalin (0.1%) caused thermal hyperalgesia which was inhibited by CP-99,994 (ID50= 1.1 mg kg-1, s.c.). There was a nonsignificant trend for an anti-algesic effect of CP-100,236 (estimated ID50 = 8.2 mg kg-1, s.c.).7 These findings support the proposal that NK1 receptor antagonists may be useful in the clinical management of pain and reinforce the need to dissociate specific and nonspecific antinociceptive effects of available compounds.

Animals↗
PubMed1994

L-745,337: a selective inhibitor of cyclooxygenase-2 elicits antinociception but not gastric ulceration in rats.

L-745,337 [5-methanesulphonamido-6-(2,4-difluorothiophenyl)-1-indan one] a selective cyclooxygenase-2 inhibitor reversed hyperalgesia induced by carrageenan in rats without causing gastric ulceration at doses 100 times those causing antinociception. In contrast, piroxicam and indomethacin produced ulcerations at antinociceptive doses. These findings demonstrate that L-745,337 possesses antinociceptive activity but has a reduced liability for gastric ulceration.

Analgesics↗
PubMed1994

Cervical spine injuries in the elderly.

We reviewed 41 patients over the age of 65 years (mean 76.5) who had suffered cervical spine injuries, 12 of them with neurological deficit. Eleven patients died during treatment, mostly from respiratory disease. Seven patients were treated by surgical stabilisation, five by halo traction, and the rest by rigid collars or halo-vests. The cervical injury was missed at the first examination in four patients. We conclude that most injuries can be treated by a rigid collar, and that the use of a halo-vest or surgical stabilisation are effective alternatives. Bed rest and traction are poorly tolerated by old people. There should be a high index of suspicion that any elderly patient who presents with a history of a fall or minor trauma may have a cervical spine injury.

Accidents↗
PubMed1994

The role of anterior surgery for vertebral fractures with and without cord compression.

The indications for anterior surgery are well defined in the upper and lower cervical spine if one accepts the importance of early restoration of stability for improved patient rehabilitation. Cannulated screw fixation of Type II fractures of the odontoid peg is a highly specialized procedure that requires technical expertise still only available at a limited number of orthopaedic centers. The engineering improvements in internal fixation for the anterior cervical spine, allied with an increasing expertise in instrumentation, have increased the tendency toward anterior stabilization for all unstable lower cervical fractures, except irreducible dislocations, irrespective of the mechanism of injury. Most thoracolumbar fractures with less than 50% to 60% canal compromise can be adequately dealt with by posterior surgery, largely because of the powerful correction inherent in the short segment, pedicle crew systems available. Anterior surgery continues to have a role in the correction of severe disruption, late deformity, and chronic anterior cord compression. No ideal anterior internal fixation system exists, but the Kaneda device is undoubtedly the strongest. The timing and indications for intervention for acute cord compression remain controversial in the absence of neurologic deterioration, although the route is undisputedly anterior in view of the usual site of compression.

Cervical Vertebrae↗
PubMed1993

A prospective randomised comparison of the dynamic hip screw and the gamma locking nail.

We made a randomised prospective comparison of the Dynamic Hip Screw and the Gamma locking nail for the internal fixation of 200 petrochanteric femoral fractures in elderly patients. There was less intraoperative blood loss and a lower rate of wound complications in the patients treated by the Gamma nail. They had, however, a high incidence of femoral shaft fracture which we relate in part to implant design. We do not recommend the use of the Gamma nail for these fractures.

Aged↗
PubMed1992

Pulmonary function after spinal surgery for idiopathic scoliosis.

Respiratory function was assessed in 20 patients with idiopathic scoliosis undergoing spinal surgery (median age, 15 years; range, 11-34 years; median preoperative vital capacity, 67%; range, 28-109% predicted). Ten patients underwent anterior spinal surgery through a thoracotomy incision, seven of whom had posterior spinal surgery as a second-stage procedure. The other ten had posterior spinal surgery as their initial operation. Postoperatively, three patients had clinical evidence of respiratory complications. Daytime oxygen saturation was reduced throughout the first postoperative week, with no significant difference between anterior and posterior spinal surgery. Hypercapnia was unusual and generally mild. Vital capacity was reduced significantly 1 week after both anterior and posterior spinal surgery (P less than 0.05). The median vital capacity 1 week after anterior spinal surgery was 45% of preoperative values compared with 78% after posterior surgery (P less than 0.05). Inspiratory muscle strength, as assessed by sniff mouth pressure, was 56% of preoperative values 1 week after anterior spinal surgery (P less than 0.05) and 85% after posterior spinal surgery (not significant). Vital capacity, but not sniff mouth pressure, remained significantly reduced 6 weeks after surgery. Oxygen saturation should be monitored noninvasively during the first week after both anterior and posterior spinal surgery even in patients at low risk of developing respiratory complications.

Adolescent↗
PubMed1992

Segmental evaluation of the surface and radiological deformity after Cotrel-Dubousset (CD) instrumentation for King type II and III. adolescent idiopathic scoliosis (AIS): surgical and etiological implications.

In this paper we report the segmental effects of CD in each of the three planes of deformity (frontal, transverse and sagittal) in 35 children with AIS (King types II and III) treated by Cotrel-Dubousset instrumentation. Patients were examined preoperatively and in follow-up at 8 weeks and one year, and 15 patients were also examined at two years. Back shape was appraised segmentally as angle of trunk inclination (ATI) at each of ten levels by ISIS and the Scoliometer. The radiographs were measured nonsegmentally for Cobb angle, apical vertebral rotation and spinal balance, and segmentally for both vertebral rotation and tilt (frontal and sagittal plane), and in the rib cage for rib-vertebra angles (RVAs).

Adolescent↗
PubMed1992

Pathogenesis of idiopathic scoliosis. The Nottingham concept.

There is no generally accepted scientific theory for the etiology of idiopathic scoliosis. Hence, current treatment is pragmatic and not based on knowledge of causation of the deformity. In Nottingham, we have evaluated data from studies of the hips, pelvis, spine, rib cage and trunk muscles in scoliotic (pre- and post operative) and control patients, cadavers and a mechanical model to formulate a new theory of etiology for idiopathic scoliosis (figs. 18 & 19 of ref. 15). Evidence is summarized for the view that idiopathic scoliosis results, in part, from a developmental abnormality in the central nervous system creating rib-vertebra angle asymmetry which leads to a cyclical failure of mechanisms of rotation control in the trunk; these involve rotation-inducing (pelvic) and rotation-defending (discal, ligamentous and costal) mechanisms acting mainly in gait. The mechanical breakdown of rotation occurs in association with a lateral spinal curvature and a lordotic segment to create the initial deformity of idiopathic scoliosis. Then, growth, both abnormal (secondary to vertebral hyper-pressures) and normal (linear spinal growth) with gravity adds to the initiating and continuing neuromuscular mechanisms to augment curve progression. This theory views the spine in the wider perspective of function in the trunk, evolution and development, all in relation to bipedalism. The goal of etiological research is ultimately to base a treatment on some knowledge of causation of the deformity.

Central Nervous System↗
PubMed1991

Anterior plate fixation in spine tumor surgery. Indications, technique, and results.

Anterior decompression by vertebrectomy is now well established as the procedure of choice to optimize neurologic recovery in patients with a deficit due to tumor involvement of the vertebral body. Fifteen patients with tumor involvement of the cervical or thoracic spine and neurologic deficit were treated by single-stage anterior decompression and AO plate stabilization. No patient suffered neurologic deterioration after surgery. All patients with thoracic lesions who were unable to walk on presentation and who managed to survive their primary disease improved to a level that allowed independent ambulation with a frame. There were no problems, such as loss of fixation or deformity. It is concluded that standard AO plates provide adequate stabilization of the cervical and thoracic spine after vertebrectomy for tumor involvement.

Bone Cements↗
PubMed1991

A segmental analysis of thoracic shape in chest radiographs of children. Changes related to spinal level, age, sex, side and significance for lung growth and scoliosis.

Thoracic ratios (TRs) were measured segmentally (T1-12) in the chest radiographs of 412 children aged 0-17 years attending hospital with minimal disorder or diseases (boys 193, girls 219). A new method for measuring TRs was used which calculates the width of the left hemithorax, the right hemithorax and the total thorax relative to T1-T12 distance. The data were analysed in 3 age groups--infancy, childhood and puberty, after the classification of Karlberg (1989). The findings are as follows. 1. The chest broadens from T1 to about T10-11. 2. Between infancy and childhood, relative to its length the chest narrows from above downwards and particularly in the lower chest (T5-12 average diminution, boys 9.5%, girls 9.8%). In the upper chest, the narrowing is more marked in girls than boys (T1-4 average diminution, boys 5.1%, girls 8.2%). 3. Between childhood and puberty, the girl's but not the boy's chest narrows further in its lower half (below T6 average diminution 3.3%). At T6 and above there is no detectable change in the relative width of the chest in either boys or girls. 4. The relative narrowing of the chest during growth appears to result from several mechanisms: (1) elevation of upper rib-vertebra angles (above 90 degrees); (2) drooping of lower rib-vertebra angles (below 90 degrees); and (3) linear rib growth being impaired relative to thoracic spinal growth in the lower ribcage (T6-12) of girls between childhood and puberty (Grivas et al. 1991 d). 5. The hypothesis is suggested that the relative narrowing of the lower chest with increasing age reduces the rotational inertia of the thorax in gait. There is a greater need for such reduction in girls because of the greater rotational inertia generated by the mass of their larger pelves. This hypothesis provides a mechanical explanation for the proportionate change in the girl's lung in the later stages of growth (Simon et al. 1972). 6. Developmentally, the left hemithorax is ahead of the right hemithorax in childhood. 7. Thoracic asymmetry favouring the right chest is found, and more so in puberty than childhood which is connected with the larger size of the thorax and lung in the adult. 8. The evidence suggests that hemithoracic development is caudocranial; this is consistent with an adaptation of the human ribcage to control spinal rotation and counterrotation when bipedal gait was acquired in evolution. 9. In progressive infantile idiopathic scoliosis, the upper chest is funnel-shaped.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1990

An analysis of the effect of the Zielke operation on the rib cage of S-shaped curves in idiopathic scoliosis.

This report evaluates the rib cage in 16 patients with S-shaped idiopathic scoliosis having the Zielke operation and followed-up for an average period of 30 months. Methods used include Cobb angle and a segmental evaluation (T7-T12) of each of convex and concave rib-vertebra angles (RVAs), rib-vertebra angle differences (RVADs), vertebral rotation, tilt and displacement. Preoperatively, the apical convex ribs droop more than the concave ribs, but the most striking difference is an asymmetry of RVAs, with increasing droop of the concave RVAs from T7-T12. The effect of the Zielke operation (on the lower curve) is: (a) to correct the Cobb angle, vertebral tilt, and displacement of the upper (thoracic) curve; (b) to derotate the spine; (c) to elevate the mobile concave ribs; (d) to have little or no effect on the stiff apical convex ribs; and (e) to increase the droop of the mobile lower convex ribs. During follow-up, six of the upper (thoracic) curves progressed. The apical RVAD and apical convex RVA are not prognostic. The concave RVAs maintain their position while convex RVAs elevate relative to the concave ribs.

Adolescent↗
PubMed1990

Harrington-Luque and Cotrel-Dubousset instrumentation for idiopathic thoracic scoliosis. A postoperative comparison using segmental radiologic analysis.

This article reports a comparison of the Cotrel-Dubousset (CD) operation with the Harrington-Luque (HL) procedure for the treatment of adolescent idiopathic thoracic scoliosis. Thirty-nine patients were studied preoperatively and postoperatively using segmental radiologic measurements including Cobb angle, end-vertebra angles (EVAs), surgical flexibility index, vertebral rotation, displacement and tilt, convex and concave rib-vertebra angles (RVAs), and kyphosis and lordosis. Cotrel-Dubousset is not significantly different from HL with respect to Cobb angle (%), surgical flexibility index, apical vertebral displacement, apical vertebral rotation, apical rib-vertebra angles, kyphosis, and lordosis. It is significantly better than the HL with respect to the correction of vertebral displacement at T10-11; lower EVA of the thoracic curve; vertebral rotation mainly above the apex; convex RVAs above the apex; and concave RVAs at T10. The surgical correction of vertebral tilt above and below the apex of the thoracic curve is significantly related to the correction of convex and concave RVAs. The view that persistent deformity of ribs is a factor needing surgical correction in some patients with adolescent idiopathic thoracic scoliosis having posterior instrumentation and fusion needs further evaluation.

Adolescent↗
PubMed1990

The operative treatment of progressive early onset scoliosis. A preliminary report.

Thirteen patients with progressive early onset scoliosis have been managed operatively in an attempt to achieve correction without bracing and to allow the spine to grow. All had posterior segmental spinal instrumentation (SSI) without fusion and 9 of 13 had anterior apical growth arrest as a separate additional procedure. At 2-year follow-up, curve correction averaged 46%. Patients who had anterior apical growth arrest and SSI without fusion had less curve deterioration than those who had SSI alone. New methods are described for 1) measuring growth of the instrumented segment of the spine and 2) calculating the predicted growth of the instrumented segment. Eight of the 13 had more than 50% of predicted growth, three had 30-50% of predicted growth, and two had less than 30% of predicted growth. Operative treatment has been successful in the short term in all but the most malignant form of infantile idiopathic scoliosis.

Bone Wires↗
PubMed1990

An analysis of the effect of the Zielke operation on S-shaped curves in idiopathic scoliosis. A follow-up study revealing some skeletal and soft tissue factors involved in curve progression.

This article analyzes the fate of S-shaped idiopathic spinal curves during follow-up in 18 patients having the Zielke VDS operation. The spinal radiographs were evaluated by Cobb angle, end-vertebra angles (EVAs), vertebral rotation, and by a new method using the tilt of the surgically fused spinal block in the frontal plane. Spinal growth was measured. Using the conventional criterion for Cobb angle progression, 83% of the lower curves and 50% of the upper curves progress. The use of EVAs shows that progression occurs mainly in the middle (thoracolumbar) segment of the spine. Curve progression occurs in the frontal plane without any significant change in vertebral rotation. The progression of the upper curve Cobb angle is not related to the progression of the Cobb angle of the lower curve; but it is related to 1) tilt of the spinal block, 2) growth of the spine below the block and 3) overall linear spinal growth (T1-S1). Progression of the upper EVA of the upper curve is associated with skeletal immaturity. The key features leading to curve progression after the Zielke operation appear to be spinal asymmetry in the frontal plane, linear spinal growth, and concave lumbar muscle tether (myostatic contracture). The surgical implications of the findings are outlined.

Adolescent↗
PubMed1989

An analysis of the effect of the Zielke operation on S-shaped curves in idiopathic scoliosis. The use of EVAs showing that correction of the thoracic curve occurs in its lower part: significance of the thoracolumbar spinal segment.

This paper analyzes the initial effect of the Zielke VDS operation on S-shaped idiopathic spinal curves in 17 patients with particular reference to the thoracic spine. The curves are evaluated by conventional methods (Cobb angle, apical vertebral rotation, kyphosis, and lordosis) and by a new method using end vertebra angles (EVAs). Three new surgical correction indices are used. In the lower curve, the surgical correction averaged 81%, and it is usually larger than that induced in the thoracic curve by about 48% (surgical correctability index). The lower curve correction is asymmetric, occurring more in its lower part (lower EVA) than in its upper part (upper EVA), a difference that the authors attribute to the restraint imposed by the rib cage on the upper EVA of the lower curve. In the upper (thoracic) curve, the surgically induced correction is variable and averages 33% (range, 6-69%). It is related significantly to preoperative bending film flexibility. The thoracic curve correction also is asymmetric, occurring more in its lower part (lower EVA) than in its upper part (upper EVA), which usually remains stable. The kyphosis angle decreases by an average of 7 degrees. The thoracic apical vertebral rotation shows variable changes. The findings show that the correction of the upper curve occurs mainly in the thoracolumbar spinal segment. It is suggested that this junctional segment of the spine is of importance in determining the limits of both instrumentation and fusion for idiopathic scoliosis.

Adolescent↗