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Biomedical subjects

N M Clarke

Publications and source records attributed to N M Clarke.

At least 19 recordsLinked to original sources
PubMed1998

The role of magnetic resonance imaging in the investigation of spinal dysraphism in the child with lower limb abnormality.

A review of magnetic resonance imaging (MRI) performed to exclude the presence of spinal dysraphism in children presenting with lower limb pathology is unrewarding in the absence of abnormal neurology. Over a 5-year period, 29 children ages 2 weeks to 15 years with a mean age of 6 years presenting with lower limb abnormalities were referred for MRI of the spine to exclude an occult neurologic cause for the deformities. More than one limb abnormality, for example pes cavus and limb length discrepancy, was present in 93% of the children, and 11 children had severe or recurrent talipes equinovarus deformity. Only two children (7%), both of whom had abnormal limb neurology, had abnormal MRI scans. In the absence of a demonstrable neurologic deficit in the lower limb, there appears to be no advantage in requesting MRI of the spine in children presenting with lower limb abnormality.

Child↗
PubMed1998

Initiation of the bony epiphysis in long bones: chronology of interactions between the vascular system and the chondrocytes.

Many events occur concurrently during the initiation of the secondary ossification center in the cartilaginous epiphyses of long bones. We have investigated the chronology of interactions between the vascular system and epiphyseal chondrocytes by culturing explanted heads of femurs and humeri from pre- and neonatal rabbits on the chorioallantoic membrane (CAM) of growing chick embryos. We confirmed that, on the whole, the epiphyseal cartilage was resistant to vascular invasion, whereas the physeal growth plate was resorbed. However, new CAM-derived cartilage canals occasionally penetrated through the articular surface. This caused death of those chondrocytes in the immediate vicinity of the canal but no further reaction. If explants already contained a bony epiphysis and were halved prior to culture, CAM-derived vessels were attracted to the spongiosa. From there they pushed into the uncalcified cartilage, indicating that calcification was not a prerequisite for vascular invasion. Where at least two vessels were in apposition, a new pseudo-ossification center was initiated: chondrocytes became hypertrophic and the matrix calcified. This suggests that cumulative release of diffusible factors from more than one vessel was the trigger for chondrocyte hypertrophy, which, in turn, led to the initiation of the bony epiphysis. CAM cultures thus provide an experimental model for both the quiescent angiogenesis of cartilage canal formation and the reactionary angiogenesis associated with chondrocyte hypertrophy. By exploiting the different anatomy of CAM-derived vascularity, events that occur concurrently in vivo can be specially separated in CAM culture.

Allantoin↗
PubMed1998

Factors regulating the rat insulin-like growth factor-binding protein-1 response to octreotide.

Insulin-like growth factor-binding protein-1 (IGFBP-1) production is increased by somatostatin and its analogues. In order to determine the time course and identify possible mechanisms of this increase in vivo we administered octreotide to rats and determined IGFBP-1 concentrations by RIA. After 60 min of anaesthesia, the mean baseline IGFBP-1 concentrations were 166 (95% confidence interval 123 to 225) ng/ml and increased in saline-infused animals to 729 (488 to 1086) ng/ml after 180 min. IGFBP-1 was stimulated transiently in response to octreotide, with circulating IGFBP-1 concentrations peaking at 1605 (1220 to 2111) ng/ml at 105 min during a continuous infusion of octreotide (100 micrograms/kg per h). In conscious chronically cannulated rats, baseline IGFBP-1 concentrations were 22 (18 to 28) ng/ml, 8-fold less than in the anaesthetised state, and were stimulated in the short term after administration of an octreotide bolus (100 micrograms/kg s.c.) to reach 88 (62 to 126) ng/ml at 60 min. A similar response was seen after i.v. administration to conscious rats. Intravenous bolus of octreotide (100 micrograms/kg) in rats anaesthetised for 3 h resulted in an increase in IGFBP-1 to peak at 1556 (1268 to 1910) ng/ml at 60 min. The IGFBP-1 response to octreotide was diminished in high-fat fed hyperinsulinaemic rats. The pattern of disappearance of iodinated IGFBP-1 from the circulation was not influenced by octreotide. The changes in GH, insulin and glucose concentrations alone did not sufficiently account for the patterns of response observed. We conclude that, in rats, octreotide stimulates IGFBP-1 acutely and this response is potentiated by factors related to anaesthesia.

Animals↗
PubMed1998

Regulation of insulin-like growth factor-binding protein-3 ternary complex formation in pregnancy.

The IGFs are believed to be important in pregnancy and are implicated in the pathophysiology of pre-eclampsia. In adults the IGFs circulate primarily with IGF-binding protein-3 (IGFBP-3) and an acid-labile glycoprotein (ALS) in a 140 kDa complex which limits IGF bioavailability. Less than 10% of IGFBP-3 is in lower molecular weight forms. We have investigated the developmental regulation of the IGF/IGFBP system in normal and pre-eclamptic pregnancies with particular emphasis on the IGFBP-3 ternary complex. Circulating levels of IGF-I, IGFBP-3 and ALS, and their degree of association in the ternary complex in the fetus increased with gestational age. In neonatal serum from deliveries <35 weeks' gestation IGFBP-3 was predominantly in 30-50 kDa form(s) and ALS was a limiting factor for ternary complex formation. In serum from deliveries >35 weeks both ALS and IGFs were limiting but approximately 25% of IGFBP-3 was unable to form the ternary complex even in the presence of excess ALS and IGF-I. Serum IGFBP-1, -2 and -6 concentrations tended to decrease with increasing gestational age. In pre-eclamptic pregnancies, amniotic fluid IGFBP-2, -3 and -6 levels decreased with gestational age while IGFBP-1 levels did not show the normal decline. We speculate that the endocrine IGF system develops in the fetus during the third trimester of pregnancy when ALS levels increase.

Adult↗
PubMed1997

Monitoring the treatment of developmental dysplasia of the hip with the Pavlik harness. The role of ultrasound.

We report the six-year results of a prospective, controlled demographic trial of developmental dysplasia of the hip (DDH) treated in the Pavlik harness using ultrasound supervision. Our aim was to assess the value of ultrasound and its role in monitoring reduction in the harness, in terms of progression or failure of reduction at an early state. From 1988 to 1994, a total of 221 patients with 370 ultrasonographically abnormal hips was treated in the Pavlik harness. This represents a treatment rate for the Southampton district of 5.1 per 1000 live births. Sixteen hips in 12 patients were not reduced in the harness and required surgical treatment; 95.7% were successfully reduced. One case of mild avascular necrosis (0.3%) was identified in those treated by harness alone. Of the 221 patients 87.8% remain under radiological review, with 3.2% of affected hips showing continued, mild acetabular dysplasia. We conclude that ultrasound monitoring has led to an acceptably low level of intervention, a high reduction rate and minimal iatrogenic complications. The trial is continuing.

Algorithms↗
PubMed1997

Improving the outcome of paediatric orthopaedic trauma: an audit of inpatient management in Southampton.

The patterns, management and outcome of non-fatal orthopaedic injury in childhood was audited over a 1 year period in Southampton. A computer-based audit (1 September 1993 to 31 August 1994) was conducted of all children aged under 15 years who were admitted to the orthopaedic unit after accidental injury. Management was audited by studying the primary conservative and operative treatment methods employed. Treatment outcome was evaluated in terms of need for secondary operative treatment, salvage internal fixation, length of hospital stay and unplanned readmission. In all, 398 children, representing 50/10,000 of the local paediatric population, were admitted with a traumatic injury. There was a significant (P < 0.001, Kolmogorov-Smirnov) seasonal variation in admission rate. There were 87.3% admissions required for fractures, 8.5% after soft tissue injury and 2.2% after joint injury. The following areas were identified where management and outcome could be improved: 1 A 12.1% readmission rate (47/346) in children with fractures owing to a 16% incidence of loss of position after closed reduction of distal radial, forearm shaft and distal humeral fractures. 2 In all, 24% of internal fixation procedures were performed as 'salvage' after failure of conservative treatment, entailing either reoperation during the initial admission or a further unplanned readmission. 3 A prolonged inpatient stay for patients with femoral fractures owing to a wide variation in treatment method. The outcome of non-fatal orthopaedic injury can be improved through the selective use of primary internal fixation of distal radial and humeral fractures and the close adherence to a management algorithm in femoral fractures. There may be a role for more specialised supervision of primary treatment of these particular fractures.

Adolescent↗
PubMed1996

Torticollis secondary to ocular pathology.

We report a series of 15 children, six male and nine female, of average age 20 months, seen at a paediatric orthopaedic clinic with torticollis. Orthopaedic examination revealed a normal range of neck movement in all cases but in seven there was palpable tightness in the absence of true shortening or contracture of the sternomastoid muscle. The patients were prospectively referred for ocular examination. In five of the 15 an ocular cause for the torticollis was detected with underaction of the superior oblique muscle in three, paresis of the lateral rectus muscle in one and nystagmus in one. Another two patients were found to have an abnormal ocular examination which was thought to be unrelated to their torticollis. Three of the patients with ocular torticollis required extra-ocular muscle surgery to abolish the head tilt and one of these had a tight sternomastoid muscle. Two of the non-ocular group had surgical release of the sternomastoid muscle; in the rest, the condition either resolved with physiotherapy or required no active treatment. We recommend that all patients with torticollis and no clear orthopaedic cause are referred for ocular assessment since it is not possible clinically to distinguish ocular from non-ocular causes.

Adolescent↗
PubMed1996

Congenital dislocation of the hip in extrauterine pregnancy.

Only two cases have been reported of congenital dislocation of the hip in infants born after extrauterine pregnancies. We report a further two and discuss the management and the variable outcome. These cases seem to confirm that congenital dislocation of the hip is associated with moulding forces rather than being a teratological abnormality.

Abnormalities, Multiple↗
PubMed1995

Oculoauriculovertebral spectrum: new manifestations.

We present a case of oculoauriculovertebral spectrum (hemifacial microsomia, Goldenhar's syndrome) found shortly after birth with right iliac hypoplasia, absent right pubic and ischial ossification centres and posterior urethral valves, which have not previously been described in this spectrum.

Abnormalities, Multiple↗
PubMed1995

Developmental regulation of circulating insulin-like growth factor-binding proteins in normal pregnancies and in pre-eclampsia.

The insulin-like growth factors (IGFs) and their binding properties (IGFBPs) are believed to play important roles in the growth and development of the human fetus. They have been implicated in the pathophysiology of pre-eclampsia. In this study we have characterized the developmental regulation, in normal and pre-eclamptic pregnancies, of IGFs and IGFBPs in maternal serum, neonatal serum and amniotic fluid. In neonatal cord serum IGFBP-1, -2 and -6 decreased with increasing gestational age. In contrast, the ternary complex and its components, IGF-I, IGFBP-3 and ALS increased with gestation. We show that while ALS is an important limiting factor for ternary complex formation in the fetal circulation, there is a fraction of IGFBP-3 which is unable to form this complex. IGFs and IGFBPs in the maternal and fetal circulation were similar in normal and pre-eclamptic pregnancies.

Amniotic Fluid↗
PubMed1995

Familial congenital pseudarthrosis of the ulna.

A mother and daughter, both presented with congenital pseudarthrosis of the ulna due to neurofibromatosis. The daughter is one of identical twins, the second twin not having a pseudarthrosis. The mother's uncle also had pseudarthrosis of the tibia. This suggests a complex variable genetic inheritance pattern for pseudarthrosis in neurofibromatosis. Despite having had no treatment, the mother had minimal symptoms, minimal deformity, and no radial head dislocation.

Child, Preschool↗
PubMed1995

Recurrent irritable hip in childhood.

Between 1989 and 1992 we admitted 426 children with an irritable hip, 363 (85.2%) once and 63 (14.8%) on 143 occasions. We assessed the records retrospectively to determine whether the groups differed and in particular whether recurrence was followed by pathological sequelae. We identified no feature which distinguished between them at either presentation. The use of bone isotope scans was greatly increased in recurrent cases, without clinical benefit. No relationship between recurrence and subsequent abnormality was identified, with 22 (42%) of the recurrences taking place in the opposite hip. The only difference was a higher incidence of 'psychosocial factors' recorded in the notes of children who presented on more than two occasions. The incidence of recurrent irritable hip is larger than previously indicated and in the presence of normal radiographs and low-grade clinical signs, more detailed investigation on subsequent admission is unlikely to be helpful.

Child↗
PubMed1995

Surgical release of the 'snapping iliopsoas tendon'.

We report 22 patients (19 women and three men) of mean age 20.8 years who had painful snapping sensations in the groin. Most were able to reproduce the click by extending the affected hip from a flexed, abducted and externally rotated position and most were tender in the adductor triangle. Plain radiographs and an arthrogram were normal. A clinical diagnosis of subluxation of the iliopsoas tendon was made. Conservative management failed in 14 patients, two of whom had bilateral pain. All 14 had surgical release of the iliopsoas tendon through a medial approach. At follow-up (mean 17 months) the click had resolved in ten hips, was occasional but painless in five and unchanged in one. The syndrome of a painful 'snapping' psoas may result in disproportionately disabling symptoms. It may be diagnosed on clinical grounds and effectively treated, when severe, by release of the iliopsoas tendon.

Adolescent↗