Showing papers by "University of Auckland published in 1992"

Fatal familial insomnia and familial Creutzfeldt-Jakob disease: disease phenotype determined by a DNA polymorphism

Abstract: Fatal familial insomnia (FFI) and a subtype of familial Creutzfeldt-Jakob disease (CJD), two clinically and pathologically distinct diseases, are linked to the same mutation at codon 178 (Asn178) of the prion protein gene. The possibility that a second genetic component modified the phenotypic expression of the Asn178 mutation was investigated. FFI and the familial CJD subtype segregated with different genotypes determined by the Asn178 mutation and the methionine-valine polymorphism at codon 129. The Met129, Asn178 allele segregated with FFI in all 15 affected members of five kindreds whereas the Val129, Asn178 allele segregated with the familial CJD subtype in all 15 affected members of six kindreds. Thus, two distinct disease phenotypes linked to a single pathogenic mutation can be determined by a common polymorphism.

Determinants of total body and regional bone mineral density in normal postmenopausal women--a key role for fat mass.

Abstract: In order to determine which clinical, anthropometric, dietary, and biochemical variables are independent predictors of total and regional bone mineral density (BMD) in normal postmenopausal women, a cross-sectional study of 140 normal postmenopausal women has been carried out. Subjects were white, aged 45-71 yr (mean 58 yr), and had no history of disorders or medication use likely to influence bone or calcium metabolism. Multiple regression analysis was used to derive models for total and regional BMD in terms of the other variables measured. The analysis indicated that total body BMD was positively related to fat mass (P less than 0.0001), serum estrone (P = 0.0095) and age at menopause (P = 0.0165), and negatively related to age (P less than 0.0001), 24-h urine calcium (P = 0.0002), sex hormone-binding globulin (P = 0.0003), and serum alkaline phosphatase activity (P = 0.0029) (R2 = 0.61). Similar relationships were found in the subregions of the total body scans and in the lumbar spine and proximal femur, with insulin-like growth factor-1, parity, and age at menarche also being related to BMD at at least two of these sites. Lean body mass was not an independent correlate of BMD at any site once fat mass was taken into account. Muscle strength, physical activity, alcohol intake, and dietary intakes of calcium, sodium and protein did not emerge as significant predictors of BMD in this homogeneous group of postmenopausal women. We conclude that total body fat is the most significant predictor of BMD throughout the skeleton and this relationship is not explicable in terms of either estrone production in fat tissue or the dependence of skeletal load-bearing on fat mass. The mechanism underlying this relationship is an important question to be addressed in bone biology.

Fat mass is an important determinant of whole body bone density in premenopausal women but not in men.

Abstract: We recently reported that total body fat mass is the principal determinant of bone density in normal postmenopausal women. We have now reexamined the relationships among these variables and lean mass in 68 healthy premenopausal women and 51 men. Areal bone density (BMD), fat mass, and lean mass were measured in total body scans by dual-energy, x-ray absorptiometry. In women, BMD was correlated with weight (r = 0.69), fat mass (r = 0.60), and lean mass (r = 0.55). In men, the respective correlations were 0.56, 0.26 (NS), and 0.51. Multiple regression analysis confirmed a codependence of female BMD on fat and lean masses, whereas male BMD was related only to lean mass. Because BMD is an areal not volumetric density, it is dependent on body size. The analysis was therefore repeated using BMD/height as an index of "true" density. Correlations with fat mass were little changed but those with lean mass were reduced (women) or eliminated (men). By multiple regression, female BMD/height was related to fat mass alone, and in men there was a borderline effect of fat (P = 0.05) but none of lean mass. As a second method to exclude a scale artifact, fat mass was expressed as percent body weight. It was related to BMD (r = 0.48) only in women. It is concluded that bone density is closely related to fat mass in premenopausal women, but less so in men. In both sexes, apparent relationships between BMD and lean mass are artifacts attributable to the use of areal density (which is dependent on body size) as a surrogate for volumetric density. The mechanism of this fat-bone density relationship is an important question to be addressed in bone biology.

Viruses as precipitants of asthma symptoms. I. Epidemiology.

Abstract: Christopher Robin had wheezles and sneezles, they bundled him into his bed. They gave him what goes with a cold in the nose, and some more for a cold in the head. They wondered if wheezles could turn into measles, if measles would turn into mumps; They examined his chest for a rash, and the rest of his body for swellings and lumps. They sent for some doctors in sneezles and wheezles, to tell them what ought to be done. All sorts and conditions of famous physicians came hurrying round at a run. They all made a note of the state of his throat, they asked if he suffered from thirst; They asked if the sneezles came after the wheezles, or if the first sneezle came first. They said, ‘If you teazle a sneezle or wheezle, a measle may easily grow. But humour or pleazle the wheezle or sneezle, the measle will certainly go.’ They expounded the reazles for sneezles and wheezles, the manner of measles when new. They said ‘If he freezles in draughts and in breezles, then PHTHEEZLES may even ensue.’ Christopher Robin got up in the morning, the sneezles had vanished away. And the look in his eye seemed to say to the sky, ‘Now, how to amuse them today?’ A. A. Milne, Now We Are Six, 1927.

The prehistoric exploration and colonisation of the Pacific

Abstract: The exploration and colonisation of the Pacific is a remarkable episode of human prehistory. Early sea-going explorers had no prior knowledge of Pacific geography, no documents to record their route, no metal, no instruments for measuring time and none for exploration. Forty years of modern archaeology, experimental voyages in rafts, and computer simulations of voyages have produced an enormous range of literature on this controversial and mysterious subject. This book represents a major advance in knowledge of the settlement of the Pacific by suggesting that exploration was rapid and purposeful, undertaken systematically, and that navigation methods progressively improved. Using an innovative model to establish a detailed theory of navigation, Geoffrey Irwin claims that rather than sailing randomly downwind in search of the unknown, Pacific Islanders expanded settlement by the cautious strategy of exploring upwind, so as to ease their safe return. The author has tested this hypothesis against the chronological data from archaeological investigation, with a computer simulation of demographic and exploration patterns and by sailing throughout the region himself.

Four modifiable and other major risk factors for cot death: The New Zealand study

Abstract: New Zealand's high mortality rate from sudden infant death syndrome (SIDS) prompted the development of the New Zealand Cot Death Study. A report of the analysis of the data from the first year has been published. This report now gives the major identified risk factors from the full 3 year data set. In this case-control study there were 485 infants who died from SIDS in the post-neonatal age group, and 1800 control infants, who were a representative sample of all hospital births in the study region. Obstetric records were examined and parental interviews were completed in 97.5% and 86.9% of subjects, respectively. As expected many risk factors for SIDS were confirmed including: lower socio-economic status, unmarried mother, young mother, younger school-leaving age of mother, younger age of mother at first pregnancy, late attendance at antenatal clinic, non-attendance at antenatal classes, Maori, greater number of previous pregnancies, the further south the domicile, winter, low birthweight, short gestation, male infant and admission to a special care baby unit. In addition, however, we identified four risk factors that are potentially amenable to modification.(ABSTRACT TRUNCATED AT 250 WORDS)

Outcome after ischemia in the developing sheep brain: an electroencephalographic and histological study.

Abstract: The role of seizures occurring with perinatal hypoxic-ischemic encephalopathies is unclear. We examined the relationships between the time course of parasagittal electroencephalographic (EEG) activity and pathological outcome following transient cerebral ischemia, which was induced in 33 chronically instrumented fetal sheep by occluding the carotid arteries after ligation of the vertebral-carotid anastomoses. The EEG was quantified with real-time spectral analysis. Histological outcome was assessed 72 hours later. After 10 or 20 minutes of ischemia, EEG activity was depressed and then progressively recovered and mild selective neuronal loss was seen. The length of this depression correlated with the duration of ischemia (r = 0.88). After 30 or 40 miniutes of ischemia, EEG activity remained depressed for 8 ± 2 hours, followed by a rapid transition to low-frequency epileptiform activity that reached maximum intensity at 10 ± 3 hours. By 72 hours, EEG intensity had fallen below control levels. This sequence of prolonged depression, epileptiform activity, and then loss of intensity was associated with the development of laminar necrosis of the underlying cortex. These electrophysiological sequelae may have prognostic value. The results indicate that after a severe hypoxicischemic insult, the parasagittal cortex becomes hyperexcitable before the final loss of activity. Secondary neuronal death may occur in this phase.

Adherence to medication regimens: updating a complex medical issue.

Abstract: Clinicians face nonadherence as the norm in everyday medical practice. The literature suggests a number of techniques that are likely to increase adherence when incorporated into regular clinical practices and routines. Central to these guidelines appears to be the doctor-patient relationship. For instance, the physician who uses understandable language, encourages open doctor-patient exchange, fosters participation by patients in their own medical care, and creates a friendly and efficient environment should increase the likelihood of adherence. Clinicians can also check adherence to medication regimens by requesting patients to bring in their pill bottles (or other prescription containers) for a discussion on how the medication appears to be working for them. This should elicit information from the patient about problems related to medication adherence. Since patient variables and social support affect adherence behaviors, eliciting information from patients about their understanding and beliefs regarding their particular illness and treatment, as well as enlisting the support of family and friends, may encourage adherence. Identifying what individual patients perceive as obstacles in following treatment regimens decreases their likelihood of nonadherence; these are difficulties that can be negotiated during the medical interview. Individualizing the treatment and minimizing its complexity may provide the solution that encourages adherent behavior. Frequent reeducation, reinforcement, and encouragement, as well as training in self-management and self-monitoring, will at the very least maximize the patient's comprehension of the illness and his or her motivation for adherence--an especially important requisite for living with a chronic condition. Some patients may even wish to openly solicit family and friends for help in the management and monitoring of their illness and treatment, and to structure their environment to support adherence. Education programs for the patient featuring handouts and pamphlets that provide information about the illness in written and illustrated form have been used successfully. Education programs such as patient-oriented package inserts to accompany the medications and brief written summaries of complex treatment plans may also be useful. The purpose of such patient education adjuncts to illness and treatment lie in the hope that they will enhance the likelihood of following treatment recommendations. Through their use, the reason for the treatment and its potential effectiveness will, it is hoped, be better understood (Ley 1988). Overall, significant advances have been made in adherence research. Measurement systems have become more finely tuned, and the definitions and criteria for adherent behaviors are more clear and precise.(ABSTRACT TRUNCATED AT 400 WORDS)

Voluntary disclosure of financial segment data: new zealand evidence

Abstract: This paper reports on the voluntary financial disclosure of segment data by New Zealand companies and relates the extent of quantified segment disclosure to firm-specific characteristics. The extent of voluntary segment disclosure varies across a sample of 29 firms listed on the New Zealand Stock Exchange. The extent of quantified segment disclosure is significantly related to firm size, financial leverage, but not to assets in place, earnings volatility or a the importance of foreign funding to the firm.

Quantum Collapses and Revivals in a Quantized Trap

Abstract: A single two-level atom, with quantized centre-of-mass motion, is constrained to move in a one-dimensional harmonic potential, while interacting with a single-mode classical travelling light field. When the atom's centre-of-mass motion is in a coherent state, we show that the atomic inversion exhibits collapses and revivals. Whereas in the Jaynes-Cummings model this behaviour occurs due to the discrete nature of the light field, in our case the behaviour is due to the discrete nature of the vibrational trap states. The Q-function for the external motion is also calculated and shown to break into two peaks in the collapse region. Finally the parameter ranges under which the collapses and revivals can be observed are discussed, as well as the possibility of an experiment.

Evolution of hereditary non-polyposis colorectal cancer.

Abstract: The prevalence of colorectal adenoma in 23 affected patients with hereditary non-polyposis colorectal cancer (HNPCC) was compared with that in an age matched forensic autopsy population. The mean ages at diagnosis of colorectal cancer in men (13) and women (10) were 39 and 37 years respectively. In HNPCC patients who presented below the age of 50 years, at least one adenoma was found in 3 of 10 (30%) men and in 4 of 9 (44%) women. In the age matched autopsy specimens of large bowel, a solitary adenoma was found in 2/42 (5%) men (p = 0.015) and 1/21 (5%) women (p = 0.0075). Of the 11 adenomas from HNPCC patients, nine were greater than 1 cm and six showed a pure villous architecture. Contiguous adenocarcinoma was observed with six adenomas. Adenomas do not occur in large numbers in HNPCC, but develop at a young age, attain a large size, often show a villous configuration, and are more prone to malignant conversion than sporadic adenomas.

The Dramatic Influence of Loading Velocity on the Compressive Response of Articular Cartilage

Abstract: Experiments were carried out to investigate the influence of loading velocity on the stiffness of the articular cartilage matrix. Compression tests were conducted on cartilage alone and cartilage-on-bone at strain-rates ranging from 10−5sec−1 to 103sec−1 and it was established that matrix stiffness increased progressively in the “low” and “medium” strain-rate regimes and assumes a limiting value at “high” rates of loading up to impact. Analysis of the strain field characteristics associated with the compression process, both at low and high velocities, suggests that two fundamentally different mechanisms of deformation control the development of cartilage matrix stiffness. At low strain-rates a consolidation-dependent stiffness occurs while at high strain rates the high stiffness results from a classical elastic deformation process. This bifurcation in the tissue's response to loading is likely to affect the redistribution of joint contact stresses being transmitted into the subchondral bone.

Chondrons from articular cartilage. V. Immunohistochemical evaluation of type VI collagen organisation in isolated chondrons by light, confocal and electron microscopy

Abstract: The pericellular microenvironment around articular cartilage chondrocytes must play a key role in regulating the interaction between the cell and its extracellular matrix. The potential contribution of type VI collagen to this interaction was investigated in this study using isolated canine tibial chondrons embedded in agarose monolayers. The immunohistochemical distribution of an anti-type VI collagen antibody was assessed in these preparations using fluorescence, peroxidase and gold particle probes in combination with light, confocal and transmission electron microscopy. Light and confocal microscopy both showed type VI collagen concentrated in the pericellular capsule and matrix around the chondrocyte with reduced staining in the tail region and the interconnecting segments between adjacent chondrons. Minimal staining was recorded in the territorial and interterritorial matrices. At higher resolution, type VI collagen appeared both as microfibrils and as amorphous deposits that accumulated at the junction of intersecting capsular fibres and microfibrils. Electron microscopy also showed type VI collagen anchored to the chondrocyte membrane at the articular pole of the pericellular capsule and tethered to the radial collagen network through the tail at the basal pole of the capsule. We suggest that type VI collagen plays a dual role in the maintenance of chondron integrity. First, it could bind to the radial collagen network and stabilise the collagens, proteoglycans and glycoproteins of the pericellular microenvironment. Secondly, specific cell surface receptors exist, which could mediate the interaction between the chondrocyte and type VI collagen, providing firm anchorage and signalling potentials between the pericellular matrix and the cell nucleus. In this way type VI collagen could provide a close functional interrelationship between the chondrocyte, its pericellular microenvironment and the load bearing extracellular matrix of adult articular cartilage.

Measurement-induced diffraction and interference of atoms

Abstract: The position of an atom passing through a standard light wave is localized by making a quadrature phase measurement on the light field. This localization can be thought of as the creation of a virtual slit (or slits) for the atom by the field measurement. Diffraction and interference behavior may be observed in the far field.

Technologies and Effects of Heterosexual Coercion

Abstract: I am concerned here with explicating some of the ways in which sexual coercion, including `unwanted sex', takes place within heterosexual relationships. It is suggested that dominant discourses on heterosexuality position women as relatively passive subjects who are encouraged to comply with sex with men, irrespective of their own sexual desire. Through the operation of disciplinary power, male dominance can be maintained in heterosexual practice often in the absence of direct force or violence. The discursive processes that maintain these sets of power relationships can be thought of as `technologies of heterosexual coercion'. Extracts from women's accounts of their experiences of unwanted and coerced sex with men are presented to show the operations and effects of these technologies of heterosexual coercion.

Cerebral Histologic and Electrocorticographic Changes after Asphyxia in Fetal Sheep

Abstract: Asphyxia can cause neurologic damage in the fetus, hot there are few data relating severity or duration of asphyxia to the degree of cerebral damage. We report cerebral histologic and electrophysiologic changes after asphyxia in chronically instrumented late-gestation fetal sheep. We reduced uterine blood flow to produce an ascending aortic blood oxygen content 7.0 in five of six without damage (p < 0.05). We conclude that severe intrauterine asphyxia for periods of 30 to 120 min can cause predominant parasagittal neuronal death and that this is associated with hypotension, severe metabolic acidosis, and suppression of EEC during the insolt. These data are consistent with the suggestion that impairment of cerebral perfusion is a critical event in localizing cerebral damage during perinatal asphyxia.

History, philosophy, and science teaching: The present rapprochement

Abstract: This paper traces the use of, and arguments for, the history and philosophy of science in school science courses. Specific attention is paid to the British National Curriculum proposals and to the recommendations of the US Project 2061 curriculum guidelines. Some objections to the inclusion of historical material in science courses are outlined and answered. Mention is made of the Piagetian thesis that individual psychological development mirrors the development of concepts in the history of science. This introduces the topic of idealisation in science. Some significant instances are itemised where science education has, at its considerable cost, ignored work in philosophy of science. Arguments for the inclusion of the history and philosophy of science in science teacher education programmes are given. The paper finishes with a list of topical issues in present science education where collaboration between science teachers, historians, philosophers, and sociologists would be of considerable benefit.

Child and adolescent (early onset) schizophrenia: a review in light of DSM-III-R.

Abstract: Early onset schizophrenia (EOS) is defined as that beginning in childhood or adolescence (under 16 or 17). Studies of EOS are infrequent, and comparative adult figures not always available, but tentative conclusions may be drawn. EOS is more common in males; symptomatology is often undifferentiated; frequencies of homotypic family disorder, premorbid schizotypal personality, and neurodevelopmental abnormalities high; outcome poor but only slightly worse than in adults; response to psychotropic drug treatment probably similar though not properly tested; and confusion with psychotic bipolar disorder particularly common. Onset before language is developed presents special diagnostic difficulties. There are a few reports of autistic children developing schizophrenia but this requires replication. Differences from adult schizophrenia are more marked when onset is in childhood than in adolescence but all are quantitative rather than qualitative suggesting that the disorders are the same and that there should be no separate category for children or adolescents.

The Solution of Massive Generalized Set Partitioning Problems in Aircrew Rostering

Abstract: The scheduling and rostering of personnel is a problem that occurs in many organizations. Aircrew scheduling has attracted considerable attention with many heuristic methods being proposed, but in recent times set partitioning optimization methods have become more popular. The aircrew rostering problem is discussed and formulated as a generalized set partitioning model. Because of the extremely large optimization models that are generated in practical situations, some special computational techniques have been developed to produce solutions efficiently. These techniques are used to solve problems arising from an airline application in which set partitioning models with more than 650 constraints and 200 000 binary variables are generated. The solutions are produced on a Motorola 68020 microprocessor in little more than three hours.