Prediction and Visualisation of Bony Impingement for Subject Specific Total Hip Arthroplasty.

Bony impingement (BI) may contribute to restricted hip joint motion, and recurrent dislocation after total hip arthroplasty (THA), and therefore, should be avoided where possible. However, BI risk assessment is generally performed intra-operatively by surgeons, which is partially subjective and qualitative. Therefore, the aim of the study was to develop a method for identifying subject-specific BI, and subsequently, visualising BI area on native bone anatomy to highlight the amount of bone should be resected. Activity definitions and subject-specific bone geometries, constructed from CT scans, with planned implants were used as inputs for the method. For each activity, a conical clearance angle (CCA) was checked between femur and pelvis through simulation. Simultaneously, BI boundary and area were automatically calculated using ray intersection and region growing algorithm respectively. The potential use of the developed method was explained through a case study using an anonymised pre-THA patient data. Two pure (flexion, and extension) and two combined hip joint motions (internal and external rotation at flexion and extension respectively) were considered as activities. BI area were represented in two ways: (a) CCA specific where BI area for each activity with different CCAs was highlighted, (b) activity specific where BI area for all activities with a particular CCA was presented. Result showed that BI area between the femoral and pelvic parts was clearly identified so that the pre-operative surgical plan could be adjusted to minimise impingement. Therefore, this method could potentially be used to examine the effect of different preoperative plans and hip motion on BI, and to guide bony resection during THA surgery.

New insights into the phase diagram of a magnetic perovskite, LaCo1/3Mn2/3O3.

We report the crystal structure of the orthorhombic perovskite LaCo1/3Mn2/3O3 as determined by neutron diffraction from 5-300 K. A high-temperature x-ray diffraction study is also reported from 290-900 K. At temperatures above 570 K, LaCo1/3Mn2/3O3 transforms to a rhombohedral structure with space group R3̄c. This rhombohedral phase is also observed in the material at high pressure and the crystal structure has been determined by in situ neutron diffraction at 4.7 GPa. Finally, the ferromagnetic behaviour has been determined by magnetometry and the magnetic structure has been determined using low temperature neutron diffraction at ambient pressure.

Kearns-Sayre syndrome: biochemical studies of mitochondrial metabolism.

Examination of oxidative metabolism in mitochondria isolated from quadriceps skeletal muscle biopsy specimens of 4 patients with Kearns-Sayre syndrome has shown that the mitochondria were tightly coupled, with maximal respiratory rates depending on the presence of adenosine diphosphate (ADP), Ca2+, or uncoupler. The state 3 respiratory rates with nicotinamide adenine dinucleotide (NAD)-linked substrates and succinate were much lower than those of control subjects. The cytochrome oxidase activities (measured with ascorbate + phenazine methosulfate as substrates) were also decreased, but this segment of the respiratory chain was not rate-limiting for succinate or NAD-linked substrate oxidation. Analyses of the steady-state reduction kinetics of the respiratory chain carriers revealed that the rate-limiting step of the impaired respiration with succinate or NAD-linked substrates lies between the c cytochromes and cytochrome oxidase. Measurement of the total substrate-reducible (at anaerobiosis) and chemically reducible levels of the cytochromes in mitochondria from 3 patients showed a severe deficiency of cytochrome a + a3 and an excess of the c cytochromes. To our knowledge, this is the first instance in which a mitochondrial electron transfer defect and cytochrome oxidase deficiency has been shown to be associated with an excess of the c cytochromes.

Rett syndrome--a gray matter disease? Electrophysiologic evidence.

Electrophysiologic dichotomy of abnormal EEGs, as reported by us previously, and normal evoked potentials, as reported in this communication, in patients with Rett syndrome, suggests a predominant gray matter pathophysiologic insult in this serious condition of unknown etiology.

Cardiomyopathy, mental retardation, and autophagic vacuolar myopathy.

Two brothers had nonobstructive hypertrophic cardiomyopathy, mental retardation, and vacuolar myopathy, and their mother died of cardiopathy at age 31. Seven families with this syndrome have been described; heredity appears to be X-linked dominant or autosomal dominant, with different expressivity in males and females. The biochemical cause of this lysosomal storage disease is unknown.

Electroencephalographic findings in Rett syndrome.

Rett syndrome is a progressive neurologic condition, affecting only girls and characterized by acquired microcephaly, dementia, seizures, autistic behavior, spontaneous hyperventilation, spasticity, hyperreflexia and a peculiar characteristic stereotypic movement disorder. A review of 35 EEGs (obtained over 0-8.5 years of follow-up) in 9 such patients revealed a striking age-related change in the electroencephalographic pattern. Often initially normal, the EEG shows a variety of epileptiform abnormalities but intact background activity between 3 and 5 years. Between 5 and 10 years of age, the background activity exhibits some slowing, epileptiform abnormalities persist and paroxysmal high-amplitude theta activity occurs over extended periods, related to spontaneous hyperventilation. After 10 years, there is a general reduction in the epileptiform activity but further slowing of the background rhythms is usually observed. As all other laboratory tests are mostly normal in Rett syndrome, EEG promises to be a powerful tool in confirming the diagnosis in a compatible setting, in follow-up of these patients, and in objective evaluation of any future therapeutic interventional modalities in this serious and common condition.

Electrophysiologic studies in neonatal adrenoleukodystrophy.

Recent electrophysiologic studies have focussed attention on the X-linked adrenoleukodystrophy (ALD) and its myeloneuropathic variant. No organized studies are, however, yet available on its relatively recently described neonatal variant. We conducted electroencephalographic, electroretinographic and evoked response studies in 2 patients with neonatal ALD. In one patient, an infant, initial EEG, hypsarrhythmic in waking and somewhat periodic in sleep, showed dramatic improvement on ACTH therapy accompanied with a seizure-free status. The EEG and clinical improvement, however, were temporary. No improvement occurred following pyridoxine therapy. Her electroretinogram (ERG), visual evoked responses (VERs) and far-field short latency brain-stem auditory evoked responses were also abnormal. The latter studies probably reflected photoreceptor degeneration, optic nerve involvement, cochlear and/or auditory nerve involvement respectively in neonatal ALD. The other patient, a 3.5-year-old girl, also had an EEG characterized by a moderate- to high-amplitude slow background activity and high-amplitude multifocal, generalized or periodic paroxysmal discharges, but presence of some better formed theta frequencies in background activity precluded a hypsarrhythmic label on her EEG. Her ERGs and VERs were totally extinct but in contrast to the first patient, she had clear-cut optic atrophy and retinitis pigmentosa on ophthalmological examination.

Electroencephalographic findings in urea-cycle disorders.

Eleven electroencephalograms in 4 infants with urea-cycle disorders were reviewed. All infants had one or more abnormal EEGs. The abnormalities consisted mainly of multiareal spikes, spike-waves, or sharp-and-slow-wave activity. In addition, one patient, a term infant, exhibited exaggerated spindle-delta bursts. This infant, and also one other at a similar age, had monorhythmic paroxysmal theta activity. Clinically, all patients had seizures shortly preceding abnormal EEGs. EEG alterations were encountered over a wide range of elevated serum ammonia levels. Normal EEGs occurred in the face of slightly elevated levels. It is concluded that epileptiform EEG alterations may be a characteristic manifestation of urea-cycle disorders.

Correlates of delayed motor nerve conduction and retinopathy in juvenile-onset diabetes mellitus.

Using a protocol designed to eliminate observer bias, we studied the relationship of duration of diabetes, age, blood glucose control, and the presence of retinopathy to motor nerve conduction velocity in patients with juvenile-onset diabetes of short duration. Conduction velocities for both the ulnar and peroneal nerves were significantly slower in the diabetic subjects than in the controls. Duration of diabetes, age, and diabetes control each had significant and independent effects on the prevalence of delayed conduction. Delayed conduction was present in more than 20% of those with diabetes of less than five years' duration, whereas retinopathy was present in none of our subjects with diabetes of the same duration. Moreover, although the presence of retinopathy was closely correlated with the presence of delayed conduction velocity, a number of diabetic subjects had one abnormality but not the other. We believe that delayed nerve conduction and retinopathy in diabetic patients are caused by multifactorial mechanisms that share a common relationship to duration, age, and degree of hyperglycemia, but which differ in at least some fundamental aspects.

Polyneuropathy, alopecia areata, and chronic lymphocytic thyroiditis.

A 14-year-old boy developed alopecia totalis shortly after a pertussis-like illness and, subsequently, developed chronic lymphocytic thyroiditis and diffuse polyneuritis.

Muscle carnitine deficiency and fatal cardiomyopathy.

A 23-month-old boy with progressive muscle weakness and severe cardiomyopathy was found to have oil red O positive vacuoles predominantly in type 1 muscle fibers. Serum carnitine was normal, but muscle carnitine content was decreased. Both parents were clinically normal, but the muscle carnitine level was low in the father. Despite oral treatment with carnitine, the condition progressed and was fatal. At autopsy, cardiac muscle showed borderline low carnitine content and numerous mitochondria, but no lipid accumulation.

Evaluation of intellectual, linguistic, and achievement variables in normal, emotionally disturbed, and learning disabled children.

This study addresses itself to developing an abbreviated test battery to assess children presenting learning difficulties in the classroom. Factor analyses of the WISC, ITPA and PIAT revealed that 85% of the total variance of these tests can be accounted for by an abbreviated battery utilizing 12 subtests from the 26 in the total from all three tests. Evidence is presented that the discrepancy between academic achievement and academic aptitude is not as great as expected, in children with apparent underachievement, when careful, reliable measures are used.

Familial poliodystrophy, mitochondrial myopathy, and lactate acidemia.

We describe a 16-year-old boy who has a progressive dementia and seizures. On investigation, he was found to have a mitochondrial myopathy and elevated lactate levels in the blood and cerebrospinal fluid. His sister died at 18 years of age of a similar condition.