Predicting patterns of long-term adaptation and extinction with population genetics

Population genetics struggles to model extinction; standard models track the relative rather than absolute fitness of genotypes, while the exceptions describe only the short-term transition from imminent doom to evolutionary rescue. But extinction can result from failure to adapt not only to catastrophes, but also to a backlog of environmental challenges. We model long-term adaptation to long series of small challenges, where fitter populations reach higher population sizes. The population's long-term fitness dynamic is well approximated by a simple stochastic Markov chain model. Long-term persistence occurs when the rate of adaptation exceeds the rate of environmental deterioration for some genotypes. Long-term persistence times are consistent with typical fossil species persistence times of several million years. Immediately preceding extinction, fitness declines rapidly, appearing as though a catastrophe disrupted a stably established population, even though gradual evolutionary processes are responsible. New populations go through an establishment phase where, despite being demographically viable, their extinction risk is elevated. Should the population survive long enough, extinction risk later becomes constant over time.

Constraints on the evolution of phenotypic plasticity: limits and costs of phenotype and plasticity

Phenotypic plasticity is ubiquitous and generally regarded as a key mechanism for enabling organisms to survive in the face of environmental change. Because no organism is infinitely or ideally plastic, theory suggests that there must be limits (for example, the lack of ability to produce an optimal trait) to the evolution of phenotypic plasticity, or that plasticity may have inherent significant costs. Yet numerous experimental studies have not detected widespread costs. Explicitly differentiating plasticity costs from phenotype costs, we re-evaluate fundamental questions of the limits to the evolution of plasticity and of generalists vs specialists. We advocate for the view that relaxed selection and variable selection intensities are likely more important constraints to the evolution of plasticity than the costs of plasticity. Some forms of plasticity, such as learning, may be inherently costly. In addition, we examine opportunities to offset costs of phenotypes through ontogeny, amelioration of phenotypic costs across environments, and the condition-dependent hypothesis. We propose avenues of further inquiry in the limits of plasticity using new and classic methods of ecological parameterization, phylogenetics and omics in the context of answering questions on the constraints of plasticity. Given plasticity's key role in coping with environmental change, approaches spanning the spectrum from applied to basic will greatly enrich our understanding of the evolution of plasticity and resolve our understanding of limits.

Evidence-Based Medicine as a Tool for Undergraduate Probability and Statistics Education

Most students have difficulty reasoning about chance events, and misconceptions regarding probability can persist or even strengthen following traditional instruction. Many biostatistics classes sidestep this problem by prioritizing exploratory data analysis over probability. However, probability itself, in addition to statistics, is essential both to the biology curriculum and to informed decision making in daily life. One area in which probability is particularly important is medicine. Given the preponderance of pre health students, in addition to more general interest in medicine, we capitalized on students' intrinsic motivation in this area to teach both probability and statistics. We use the randomized controlled trial as the centerpiece of the course, because it exemplifies the most salient features of the scientific method, and the application of critical thinking to medicine. The other two pillars of the course are biomedical applications of Bayes' theorem and science and society content. Backward design from these three overarching aims was used to select appropriate probability and statistics content, with a focus on eliciting and countering previously documented misconceptions in their medical context. Pretest/posttest assessments using the Quantitative Reasoning Quotient and Attitudes Toward Statistics instruments are positive, bucking several negative trends previously reported in statistics education.

Transplantation of hNT neurons into the ischemic cortex: Cell survival and effect on sensorimotor behavior

Cell transplantation offers a potential new treatment for stroke. Animal studies using models that produce ischemic damage in both the striatum and the frontal cortex have shown beneficial effects when hNT cells (postmitotic immature neurons) were transplanted into the ischemic striatum. In this study, we investigated the effect of hNT cells in a model of stroke in which the striatum remains intact and damage is restricted to the cortex. hNT cells were transplanted into the ischemic cortex 1 week after stroke induced by distal middle cerebral artery occlusion (dMCAo). The cells exhibited robust survival at 4 weeks posttransplant even at the lesion border. hNT cells did not migrate, but they did extend long neurites into the surrounding parenchyma mainly through the white matter. Neurite extension was predominantly toward the lesion in ischemic animals but was bidirectional in uninjured animals. Extension of neurites through the cortex toward the lesion was also seen when there was some surviving cortical tissue between the graft and the infarct. Prolonged deficits were obtained in four tests of sensory-motor function. hNT-transplanted animals showed a significant improvement in functional recovery on one motor test, but there was no effect on the other three tests relative to control animals. Thus, despite clear evidence of graft survival and neurite extension, the functional benefit of hNT cells after ischemia is not guaranteed. Functional benefit could depend on other variables, such as infarct location, whether the cells mature, the behavioral tests employed, rehabilitation training, or as yet unidentified factors.

Genetic assimilation can occur in the absence of selection for the assimilating phenotype, suggesting a role for the canalization heuristic

Genetic assimilation occurs when an acquired trait loses dependency on its environmental trigger and becomes an inherited trait. According to the standard quantitative genetic model for genetic assimilation, the trait is determined by the contributions of multiple genes. Trait expression occurs at a lower threshold with the trigger. Selection for the trait in the presence of the trigger increases the frequency of the trait-determining alleles. Eventually these alleles become frequent enough to breach the higher threshold for expression in the absence of the trigger. This loss of dependence on the trigger signifies genetic assimilation. Here I show that genetic assimilation can occur in the absence of selection for the trait in an evolutionary simulation of a gene network model. This contradicts the prediction of the standard quantitative genetic model, but is consistent with an explanation in terms of the canalization heuristic.

Transplanted human fetal neural stem cells survive, migrate, and differentiate in ischemic rat cerebral cortex

We characterize the survival, migration, and differentiation of human neurospheres derived from CNS stem cells transplanted into the ischemic cortex of rats 7 days after distal middle cerebral artery occlusion. Transplanted neurospheres survived robustly in naive and ischemic brains 4 wk posttransplant. Survival was influenced by proximity of the graft to the stroke lesion and was negatively correlated with the number of IB4-positive inflammatory cells. Targeted migration of the human cells was seen in ischemic animals, with many human cells migrating long distances ( approximately 1.2 mm) predominantly toward the lesion; in naive rats, cells migrated radially from the injection site in smaller number and over shorter distances (0.2 mm). The majority of migrating cells in ischemic rats had a neuronal phenotype. Migrating cells between the graft and the lesion expressed the neuroblast marker doublecortin, whereas human cells at the lesion border expressed the immature neuronal marker beta-tubulin, although a small percentage of cells at the lesion border also expressed glial fibrillary acid protein (GFAP). Thus, transplanted human CNS (hCNS)-derived neurospheres survived robustly in naive and ischemic brains, and the microenvironment influenced their migration and fate.

Distinctive enchondromatosis with spine abnormality, regressive lesions, short stature, and coxa vara: importance of long-term follow-up

We report a girl with a unique type of enchondromatosis observed from birth to puberty. Radiographic abnormalities documented at the age of 14 months included distinctive spondylometaphyseal enchondromatous types of lesions with minimal involvement of the short tubular and flat bones. Follow-up radiographic examinations documented progressive coxa vara and hypoplasia/dysplasia of the left ulna. At puberty, the short tubular bones appeared normal. There was marked regression of the flat bone, rib, and spinal lesions. This case shows the importance of long-term observation of unclassified forms of skeletal dysplasia.

Premature calvarial synostosis and epidermal hyperplasia (Beare-Stevenson syndrome-like anomalies) resulting from a P250R missense mutation in the gene encoding fibroblast growth factor receptor 3

We report on a patient with a severe premature calvarial synostosis and epidermal hyperplasia. The phenotype was consistent with that of a mild presentation of Beare-Stevenson syndrome but molecular analysis of the IgIII-transmembrane linker region and the transmembrane domain of the gene encoding the FGFR2 receptor, revealed wild-type sequence only. Subsequently, molecular analysis of the FGFR3 receptor gene identified a heterozygous P250R missense mutation in both the proposita and her mildly affected father. This communication extends the clinical spectrum of the FGFR3 P250R mutation to encompass epidermal hyperplasia and documents the phenomenon of activated FGFR receptors stimulating common downstream developmental pathways, resulting in overlapping clinical outcomes.

The measured level of prion infectivity varies in a predictable way according to the aggregation state of the infectious agent

Transmissible spongiform encephalopathies are believed to be caused by an infectious form of the prion protein, designated PrP(Sc). The concentration of PrP(Sc) is often poorly correlated to the level of infectivity. Infectivity can be measured in two ways, namely endpoint titration and the incubation time assay, but patterns of infectivity vary depending on which method is used. These discrepancies can be explained by variation in the aggregation state of PrP(Sc). Both methods of measuring infectivity are modelled mathematically, and the theoretical results are in agreement with published data. It was found to be theoretically impossible to characterise prion infectivity by a multiple of a single quantity representing 'one prion', no matter how it is measured. Infectivity is instead characterised by both the number and sizes of the PrP(Sc) aggregates. Apparent discrepancies arise when these complexities are reduced to a single number.

Designing drugs to stop the formation of prion aggregates and other amyloids

Amyloid protein aggregates are implicated in many neurodegenerative diseases, including Alzheimer's disease and the prion diseases. Therapeutics to block amyloid formation are often tested in vitro, but it is not clear how to extrapolate from these experiments to a clinical setting, where the effective drug dose may be much lower. Here we address this question using a theoretical kinetic model to calculate the growth rate of protein aggregates as a function of the dose of each of three categories of drug. We find that therapeutics which block the growing ends of amyloids are the most promising, as alternative strategies may be ineffective or even accelerate amyloid formation at low drug concentrations. Our mathematical model can be used to identify and optimise an end-blocking drug in vitro. Our model also suggests an alternative explanation for data previously thought to prove the existence of an entity known as protein X.

Clinical findings in a patient with FGFR1 P252R mutation and comparison with the literature

We report on a patient with the skeletal findings of Jackson-Weiss syndrome, who manifests only mild craniofacial anomalies. Molecular analysis of her fibroblast growth factor receptor 1 gene (FGFR1) identified a heterozygous P252R missense mutation, previously only reported with FGFR1-Pfeiffer syndrome like manifestations. Mutations in the immunoglobulin-like, II-III (IgII-III) linker region of FGFR1 and FGFR3 molecules may present as a skeletal dysplasia affecting the appendicular skeleton including, brachydactyly, short broad middle phalanges, phalangeal epiphyseal coning and broad halluces. This communication is a further example of the phenomenon of an activated FGFR molecule resulting in overlapping manifestations in FGFR syndromes.

Evaluation and management of mechanical dysfunction in continent colonic urinary reservoirs

PURPOSE

We analyze a group of patients who presented with mechanical dysfunction of the reservoir and/or efferent limb of a continent colonic urinary diversion, and establish an evaluation and management algorithm.

MATERIALS AND METHODS

A total of 16 patients with a mean age of 58 years and 1 or more symptoms related to continent colonic urinary diversion were evaluated. Presenting symptomatology included difficult catheterization in 8 cases (50%), disabling incontinence in 8 (50%) and recurrent urinary tract infections in 6 (37.5%). All patients had normal, nonobstructed, nonrefluxing upper tracts and none presented with stone disease. Urological evaluation consisted of catheterization, fluoroscopy and urography of the pouch, retrograde urography of the external limb and urodynamics (enterocystometrogram and outlet pressure profilometry).

RESULTS

Of the 8 patients with difficulty with catheterization 4 had stomal stenosis, 2 had an elongated and redundant external limb, and 2 had a false passage. Diagnosis was established by the inability to catheterize, fluoroscopy of the pouch and retrograde urography. Disabling incontinence occurred in 8 patients, including 7 who presented with an incompetent outlet and 2 with high pressure intestinal contractions of the reservoir. The aforementioned abnormalities were diagnosed by a combination of retrograde urography, urography of the pouch and urodynamics. Recurrent symptomatic urinary infections were observed in 5 patients of the previous groups and in another with an hourglass reservoir, which was primarily diagnosed by urography of the pouch. Surgical correction in 15 patients included outlet reinforcement, reservoir revision, stomal or external limb revision and conversion to a urinary conduit. Surgical treatment was successful in 14 of 15 patients (93%).

CONCLUSIONS

Catheterization difficulty requires retrograde urography to define possible anatomical abnormalities (false passage, conduit elongation) if catheterization and fluoroscopy of the pouch do not demonstrate stomal stenosis. Urinary incontinence benefits from enterocystometry and outlet pressure measurement to determine reservoir and external limb function. Recurrent urinary tract infections not related to ureteral obstruction or reflux requires fluoroscopy of the pouch and external limb to determine abnormalities in patients with detubularization and localization of areas of urine pooling.

Fluctuations in HIV-1 viral load are correlated to CD4+ T-lymphocyte count during the natural course of infection

Viral load fluctuates during the natural course of asymptomatic HIV-1 infection. It is often assumed that these fluctuations are random around a set point or underlying growth trend. Using longitudinal data, we tested whether fluctuations in viral load can be better explained by changes in CD4+ T-cell count than by a set point or trend of exponential growth. The correspondence between viral load and CD4+ T-cell count could be described by a simple mathematical relation. Using a bootstrapping approach, the hypothesis that viral load fluctuations are random around a set point was rejected with p < .00005. The hypothesis that viral load fluctuations are random around a trend of exponential growth was rejected with p < .005. Viral load data was explained better by changes in CD4+ T-cell counts than by a set point or by a trend of exponential growth. The implications of this finding for improved prognostication are discussed.

Antenatal detection and management of suprarenal masses

The indications for, and timing of, surgical intervention for suprarenal masses detected prenatally are unclear. Also, the definitive diagnosis of suprarenal masses using imaging studies is difficult at best. We report 2 cases of antenatally detected suprarenal masses. One case represents an initial cystic mass expanding and becoming solid that had benign pathologic features. The second case was a stable solid mass that, on exploration, was malignant. Management options are discussed.

The kinetics of proteinase K digestion of linear prion polymers

Transmissible spongiform encephalopathies such as scrapie are caused by a protein-only infectious agent, known as a prion. It is not clear how a protein can be capable of replicating itself, and the mechanism remains controversial. One influential model hypothesizes that prions are nucleated, macroscopically linear polymers. We investigated the theoretical kinetics of this model and derived predictions which could be used to test the model. In the model, the polymerization and depolymerization rates are independent polymer size. This leads to an exponential size distribution at equilibrium. In agreement with a prediction stemming from this size distribution, the average size of PrP-res polymers was proportional to the square root of the concentration of PrP-res in a published study of in vitro conversion. Prion digestion by proteinase K (PK) is predicted to be biphasic. The second phase of digestion should be virtually independent of the PK concentration and should depend on the initial size distribution of prion polymers. For initially equilibrated polymers with an exponential size distribution, phase two digestion is exponential at a predicted rate. This rate varies in a defined way with the concentration used for equilibration and with other parameters which affect the average polymer size.

Variability in kyphomelic dysplasia

Four infants with kyphomelic dysplasia ascertained from three families demonstrate variability within the syndrome. In the first family, sibling recurrence in female sibs was noted with atypical kyphomelic dysplasias, suggesting autosomal recessive inheritance. In the second family, with a male affected with the 'typical findings' of lethal kyphomelic dysplasia, diagnosis of a skeletal dysplasia was suspected at 29-30 weeks' gestation following US detection of short, bent femurs. In the third family, with a female affected, severe radiographic changes were documented at birth. The clinical course of the disease was mild with almost complete regression of the radiographic findings at the age of 7 years.

Mesomelic dysplasia with periosteal thickening, radio-humeral dislocation, osteoporosis and multiple fractures

We report a boy with a new form of mesomelic dysplasia characterised by short stature, multifocal periosteal thickening, radio-humeral dislocation, osteoporosis and multiple fractures with minimal trauma. Electrophoresis of fibroblast collagens detected defects in type III and type V collagen.

CONCLUSION

Bone dysplasias presenting with osteopenia, abnormal trabecular pattern, bone fragility, and periosteal thickening suggest a collagenopathy. A possible collagen defect requires biochemical investigations.

Feeding problems in infants with gastro-oesophageal reflux disease: a controlled study

OBJECTIVE

Gastro-oesophageal reflux disease (GORD) in infants is commonly associated with feeding problems but has not been subject to systematic controlled study. We evaluated feeding, dietary, behavioural data obtained from systematic objective studies of six-month old infants with and without GORD.

METHODS

Infants with GORD (defined by 24-h pH monitoring, n = 20), and age, gender, gestation, and socio-economic matched healthy infants (n = 20) had standardised assessments of dietary intake, oromotor function by videoanalysis (Feeding Assessment Schedule, FAS), and infant feeding behaviour by Testers and Maternal Ratings (TRIB and MRIB). Videofluoroscopic analyses of swallowing was undertaken in 11/20 GORD infants and analysed by standardised paediatric check list.

RESULTS

Compared with control data: GORD infants had significantly lower energy intakes; the FAS showed GORD infants to have significantly fewer adaptive skills and readiness behaviour for solids, significantly more food refusal and food loss; the TRIB showed GORD infants to be significantly more demanding and difficult with feeds; and the MRIB revealed that mothers of GORD infants had significantly more negative feelings, significantly less enjoyment of feeds, and reported significantly more crying behaviour. On videofluoroscopy, oral-preparatory and oral phase problems predominated, particularly with solids, silent aspiration occurred during the pharyngeal phase in 2/11, and delayed oesophageal transit occurred in 4/11.

CONCLUSIONS

Feeding problems affecting behaviour, swallowing, food intake, and mother-child interaction occur in infants with GORD, who displayed a lack of development of age-appropriate feeding skills. The contribution of feeding problems to morbidity in GORD in infants has been underestimated in the past.

Quantifying the kinetic parameters of prion replication

The mechanism of protein-only prion replication is controversial. A detailed mathematical model of prion replication by nucleated polymerisation is developed, and its parameters are estimated from published data. PrP-res decay is around two orders of magnitude slower than PrP-sen decay, a plausible ratio of two parameters estimated from very different experiments. By varying the polymer breakage rate, we reveal that systems of short polymers grow the fastest. Drugs which break polymers could therefore accelerate disease progression. Growth in PrP-res seems slower than growth in infectious titre. This can be explained either by a novel hypothesis concerning inoculum clearance from a newly infected brain, or by the faster growth of compartments containing smaller polymers. The existence of compartments can also explain why prion growth sometimes reaches a plateau. Published kinetic data are all compatible with our mathematical model, so the nucleated polymerisation hypothesis cannot be ruled out on dynamic grounds.

Measurement of radiation dose received by the hands and thyroid of staff performing gridless fluoroscopic procedures in children

The aim of this study was to confirm that the radiation doses received by attendants who manually restrain infants during fluoroscopic procedures are low. Doses to the hands and neck of three radiologists and three nurses performing or assisting at all the fluoroscopic procedures in a children's hospital were measured for 1 month using thermoluminescent dosemeters. All fluoroscopy on children at this hospital is performed without an antiscatter grid. Total doses for the neck ranged from 20 to 50 microSv per week and for hands from 40 to 210 microSv per week. These doses were shared by the three radiologists and the three nurses. Individual doses received per staff member are very small when compared with the doses received by interventional radiology staff. Doses received by staff in this study were of the order of 5% of the limit advised by the National Health and Medical Research Council of Australia (NHMRC) for radiation workers. Nurses received larger doses than radiologists and steps will be taken to reduce this dose further.

Coexistent orbital and cerebellar venous anomalies in linear sebaceous naevus syndrome

BACKGROUND

Orbital venous anomalies can result in significant morbidity and have been reported in association with other venous anomalies, some with the potential for serious complication.

METHODS/RESULTS

We present a case of an orbital venous anomaly coexistent with a large cerebellar venous angioma and a linear sebaceous naevus. Clinical features, associations, complications and management principles are presented.

CONCLUSION

Upon clinical recognition of an orbital venous anomaly, brain imaging and appropriate clinical assessment should be considered in light of the possibility of coexistence of potentially life-threatening lesions.

Dysosteosclerosis

A 5 1/2 year old boy presented with delayed development and loss of vision. A skeletal survey showed osteosclerosis consistent with dysosteosclerosis. Some unusual features of dysosteosclerosis are discussed.

Case report: neonatal platyspondylic dwarfism--a new form

A new type of neonatal bone dysplasia is reported. Unusual radiographic abnormalities (platyspondyly with unique shape of the vertebral bodies, shortening of the long tubular bones without signs of rickets or metaphyseal dysplasia, marked shortening of well-ossified short tubular bones, schneckenbecken-like pelvis with tri-radiate acetabulum, pseudoepiphysis of the right ulna, unusual shape of calcaneus and periarticular calcifications) allow designation of this disorder as a new form of neonatal dwarfism.

Microcephalic, osteodysplastic, primordial dwarfism

A case of microcephalic, osteodysplastic, primordial dwarfism (cephaloskeletal dysplasia of Taybi and Linder) is reported. This rare disease is characterised by unique clinical appearances and diagnostic radiographic findings. It is also associated with distinctive brain abnormalities. The latter include micrencephaly, lissencephaly, corpus callosum aplasia/agenesis and unusual histological brain abnormalities.

Cystic encephalomalacia and intrauterine herpes simplex virus infection

Cystic encephalomalacia occurred in two preterm infants who had proven intrauterine herpes simplex virus type 2 infection. Calcification was evident in the basal ganglia. Follow-up scans indicated that the cysts had resolved over a period of two months in one infant, while in the case of the other, the cysts became progressively larger with significant ventricular dilatation developing. While cystic changes in the brain of preterm infants are usually due to periventricular leukomalacia, intrauterine infection needs to be considered as a possible cause. Antiviral treatment may be of benefit to infants with herpes simplex virus infection.

Rare primary cranial vault and base of the skull tumors in children. Report of 30 cases with a short literature review

Twenty-six cases of rare primary cranial vault tumors are reported, together with 4 cases of primary tumors of the base of the skull and 3 cases of monostotic cranial neuroblastoma. Whereas some rare primary cranial vault tumors may present with characteristic radiographic patterns (e.g. hemangioma, aneurysmal bone cyst, osteoma, progonoma), most of them can be recognised only after histology. The most frequent tumor in the region of previous irradiation is osteosarcoma. The only "common" primary bone tumor of the base of the skull is chordoma. The radiological differential diagnosis of primary tumors of the skull vault and base is discussed.

Primary sacral bone tumours in children (report of 16 cases with a short literature review)

16 cases of primary sacral bone tumours in children are reported. These include 13 patients with Ewing's sarcoma and 3 with very rare primary sacral bone tumours in childhood--chordoma, haemangiopericytoma and osteoblastoma. All sacral bone tumours, with the exception of Ewing's sarcoma are very rare in childhood. The possibility of a sacral tumour should be considered in a child with radiculopathy. CT and MR make the diagnosis of primary sacral bone tumours much easier with the added possibility of recognition of the true nature of the lesion in many instances. Reports of primary sacral bone tumours in children are scarce. Most of the patients are incorporated in adult series which do not specify the age of the child and the site of the tumour. The purpose of this paper is to describe 16 children with primary sacral bone tumours.

Soft-tissue tumors of the hand and wrist of children

We report 23 children with soft-tissue tumors of the hand and wrist. Tumors of blood and lymph vessel origin accounted for nine patients; giant-cell tumors of tendon sheaths and tumoral calcinosis occurred in four patients each and soft-tissue chondroma in three. Synovial osteochondromatosis and aggressive fibromatosis were each represented by one patient. Finally, there was one child with a malignant soft-tissue tumor, an embryonal rhabdomyosarcoma of the hand. Hand and wrist ganglia were excluded. Imaging methods used in investigating hand and wrist lesions are discussed but plain radiography remains the first and often only examination necessary.

Congenital cystic adenomatoid malformation of the lung. Presentation of 16 cases

Congenital cystic adenomatoid malformation (CCAM) of the lung is one of the rarest causes of neonatal distress. The principal radiological sign of CCAM is an intrapulmonary mass of soft tissue density, containing cystic areas of different sizes and shapes. The mass usually compresses the rest of the affected lung and displaces the mediastinum and heart to the opposite side, compressing the lung which is often therefore hypoplastic. If CCAM is diagnosed in utero by ultrasound, the treatment of choice is surgery as soon as possible after birth, with good survival rates. Sixteen cases of CCAM are presented, one with bilateral disease, diagnosed at different times, and one with an associated prune belly syndrome, to be added to the 405 already reported in the literature, and their clinical, radiological and pathological features are described.

Neonatal cranial ultrasonography as predictor of 2 year outcome of very low birthweight infants

Real time ultrasound scans using an ATL 300C sector scanner with 5-7.5 MHz transducer were performed on days 1, 4, 7 and thereafter as clinically necessary on 153 consecutively discharged very low birthweight (VLBW) infants. One hundred and forty-six long-term survivors were assessed fully at 2 years. The prevalence of cerebroventricular haemorrhage (CVH) in these survivors was 34.2% (grade 1-21.2%; grade 2-4.8%; grade 3-3.4%; grade 4-4.8%), ventricular dilatation 19.9% (including 4.1% with ventriculoperitoneal shunt), and ischaemia 9%. Impairments at 2 years were classified as nil, mild, moderate, severe or multiply severe, based on the criteria of Kitchen et al. Overall, 120 infants (82.2%) were unimpaired and 6.2% had mild, 3.4% had moderate, 4.1% had severe and 4.1% had multiply severe impairment. The major factors associated with impairment were gestational age less than 28 weeks, birthweight less than 1000 g, vaginal delivery, respiratory distress syndrome, mechanical ventilation, pulmonary air leaks and CVH. When these factors were reanalysed in a logistic regression model for odds ratios, only CVH (P less than 0.005) and birth by spontaneous vaginal delivery (P less than 0.05) were significant. The prevalence of impairment was 11.4% with no CVH, 6.5% grade 1, 71% grade 2, 20.0% grade 3 and 100.0% grade 4 CVH. The sensitivity of CVH of grade 2 or greater as a screening test was 64.7% for impairment, 78.6% for cerebral palsy and 70% for severe intellectual handicap. The mean general quotient (GQ) (Griffiths) at 2 years for infants with CVH was 89.1, and 97.5 for those without CVH (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

A spectrum of skeletal anomalies associated with pulmonary agenesis: possible neural crest injuries

Six cases of unilateral pulmonary agenesis with skeletal and other deformities have been diagnosed in our hospitals. The various pulmonary, spinal, rib and limb anomalies with their possible inter-relationships were examined and described in detail and comparison with previously reported cases was made. It became apparent that the limb abnormalities which most constantly involved hypoplasia of the phalanges of a thumb with varying metacarpal and radial anomalies, were ipsilateral to the pulmonary agenesis in all cases. The spinal deformities involved degrees of failure of segementation of T1-T3 with other vertebrae randomly involved. Rib abnormalities also varied and did not necessarily correspond to the same side as the pulmonary agenesis. The concept of the anomalies all being part of a group of neural crest injuries was then explored.

Familial renal abnormalities associated with the oligohydramnios tetrad secondary to renal agenesis and dysgenesis

Thirty-four families of index cases with the oligohydramnios tetrad secondary to renal agenesis/dysgenesis were screened for renal abnormalities using Real Time ultrasonography. The index cases were separated into two groups. Group 1 consisted of cases of perinatally lethal renal disease and Group 2 of cases of renal dysgenesis secondary to the urethral obstruction malformation. Renal ultrasound screenings of 23 families in Group 1 demonstrated two previously unidentified cases of unilateral renal agenesis in siblings. Screening of 11 families in Group 2 revealed one sibling with a hydronephrotic kidney and one parent with an ectopic pelvic kidney. There is a recurrence risk of 3.5-5% in families with perinatal lethal renal disease and an increased risk of silent renal anomalies in first degree family members. The recurrence risk is low in families of infants with renal dysgenesis secondary to the urethral obstruction malformation, but immediate family members are at increased risk of structural and functional urinary anomalies. Routine renal ultrasound screening of first degree relatives of infants with lethal renal agenesis and dysgenesis is recommended.

Obliterative bronchiolitis due to Mycoplasma pneumoniae infection in a child

A 6-year-old girl presented with Mycoplasma pneumoniae involving the right upper and lower lobes. She made a slow but complete recovery with resolution of the radiological changes. She re-presented 5 years later with a productive cough, recurrent wheezing and physical and radiological signs suggestive of obliterative bronchiolitis. This diagnosis was confirmed by ventilation - perfusion (V/Q) lung scan, and bronchography. The case highlights the value of V/Q scanning in the diagnosis of obliterative bronchiolitis and confirms the previous reports that mycoplasma infections are not always benign.

Spontaneous neonatal renal vein thrombosis

A case of spontaneous neonatal renal vein thrombosis is presented. A 1 week old, 36 week gestation, male child presented with gross haematuria and a large right flank mass. Investigations including intravenous pyelogram, ultrasound and venacavogram indicated the diagnosis. The child was clinically well, with normal renal and clotting function. No predisposing cause could be found. A conservative approach to treatment was undertaken in view of the normal renal function, and no evidence of consumptive coagulopathy or pulmonary emboli. The child remains well, but may require nephrectomy in the future.

Primary vertebral tumours in children. Report of 20 cases with brief literature review

20 cases of primary benign and malignant bone tumours in children were reported. The most common tumours were Ewing's sarcoma, aneurysmal bone cyst, benign osteoblastoma and osteoid osteoma. Some rare primary bone tumours in children (osteochondroma, chondroblastoma?, primary lymphoma of bone and neurofibromatosis with unusual cervical spinal changes) were also reported. The authors believe that radiographic findings together with clinical history and clinical examination may yield a high percentage of accurate diagnoses. Although microscopy is essential in the final diagnosis, the microscopic report should be viewed with caution.

Multifocal chronic osteomyelitis of unknown etiology. Report of five cases

Five cases of chronic, inflammatory, multifocal bone lesions of unknown etiology are reported. Although bone biopsy confirmed osteomyelitis in each case in none of them were organisms found inspite of an extensive work up. Different clinical course of the disease reflects different aetiology in respective cases. These cases present changing aspects of osteomyelitis emerging since introduction of antibiotics.

Mandibular and para-mandibular tumors in children. Report of 16 cases

Sixteen cases of mandibular tumors or paramandibular soft tissue tumors with mandibular involvement are reported. These include such rare mandibular tumors or tumor-like conditions as melanotic progonoma, intraosseous haematoma secondary to von Willebrand's disease, post-irradiation osteosarcoma, monostotic eosinophilic granuloma, aneurysmal bone cyst and osseous hemangiopericytoma. Three cases of cherubism, one of fibrous dysplasia or aggressive fibromatosis and one of central giant cell reparative granuloma are also reported. The soft tissue tumors comprise round cell sarcoma, parotid adeno-carcinoma with generalised metastases, embryonal rhabdo-myo-sarcoma, neuro-fibro-sarcoma and congenital cystic hygroma. In all the cases the disease was well advanced when the patient presented for X-ray examination. The specific X-ray diagnosis of mandibular and paramandibular tumors in childhood is more difficult than that of similar tumors in other parts of the body.

Neonatal death dwarfism. (A further report)

Seven cases of rare "Neonatal Death Dwarfism" observed recently in three major Children's Hospitals in Australia are reported. These include Diastrophic Dwarfism, Achondrogenesis II, Lethal Form of Hypophosphatasia, Homozygous Achondroplasia, Minor Form of Asphyxiating Thoracic Dystrophy, Achondrogenesis II (?) and Unclassified Lethal Bone Dysplasia. In all the patients the clinical diagnosis was uncertain or incorrect, whereas a conclusive radiographic diagnosis could be made after X-ray examination in all but one of the cases. Skeletal survey should be performed in each case of neonatal death dwarfism.

Asphyxiating thoracic dystrophy without respiratory disease: report of two cases of the latent form

Two cases of the latent form of Asphyxiating Thoracic Dystrophy or Asphyxiating Thoracic Dystrophy without respiratory disease or respiratory problems are reported. The skeletal survey was diagnostic in both of them. In the first case it was performed after the pelvic film, ordered because of externally rotated thighs, showed triradiate acetabulum. In the second case the skeletal survey was requested because of undiagnosed mental retardation syndrome.