Dystrophic neurite formation associated with age-related beta amyloid deposition in the neocortex: clues to the genesis of neurofibrillary pathology

The formation of dystrophic neurites associated with beta amyloid plaques in Alzheimer's disease (AD) appears to involve a transformation of normal neuronal cytoskeletal proteins. In order to investigate what may be the earliest neuronal changes associated with the development of dystrophic neurites, we have examined the neurochemical profile of abnormal neuritic processes associated with the beta amyloid deposition in non-AD, aged cases. In all non-AD individuals demonstrating some degree of beta amyloid deposition in the superior frontal gyrus, clustered swollen and ring-like structures, located principally in layers II and III, were labeled with antibodies to phosphorylated and nonphosphorylated domains of the middle and high molecular weight neurofilament subunits. These abnormal neurites were not immunolabeled for tau or ubiquitin or stained with thioflavine S. Double labeling for neurofilaments and thioflavine S confirmed that these clusters of dystrophic neurites were associated with plaque-like deposits. These results show that anatomically and neurochemically specific forms of dystrophic neurites can occur in non-AD cases that contain beta amyloid deposition. If these abnormal neurites correspond to an immature form of the dystrophic neurites found in the neuritic plaques of Alzheimer's disease, then neurofibrillary pathology associated with this disease may begin with an initial misprocessing and accumulation of neurofilament proteins. Furthermore, these data are consistent with the proposal that the development of neurofibrillary pathology may begin with neurofilamentous hypertrophy in damaged distal processes followed by reactive changes in the cell bodies of origin of these fibers involving cytoskeletal alterations that ultimately lead to neurofibrillary tangle formation.

Comparison between broad-band ultrasound attenuation of the calcaneum and total body bone mineral density in children

We measured broad-band ultrasound attenuation (BUA) in the calcaneum using the prototype Paediatric Contact Ultrasound Bone Analyser (CUBA) and total body bone mineral density (TBBMD) using dual-energy X-ray absorptiometry (DXA) (Hologic QDR-1000W) in 58, 7-17-year-old healthy children and adolescents. Calcaneal BUA was significantly related to TBBMD (r = 0.74, p < 0.001), and both the calcaneal BUA and TBBMD were significantly correlated with age and body weight. We conclude that calcaneal BUA reflects bone mineral density (BMD) in healthy children and adolescents; however, BMD measured by CUBA appears to be less sensitive than that measured by DXA. Since BUA reflects structural properties of bone, as well as density, it may complement radiological techniques of bone density measurement in the assessment of paediatric conditions associated with fracture risk.

Yeast artificial chromosome cloning and chromosomal localization of the abundant odontogenic keratocyst protein elafin

An imbalance in human leucocyte elastase (HLE) activity is widely recognized to play an important pathological role in a number of human diseases. An earlier report has described greater transcription of elafin, an endogenous inhibitor of HLE, in epithelia of odontogenic keratocysts of the jaw than in normal oral mucosa. The elafin gene was now localized to chromosome 20q11.2-13.1 using a combination of somatic cell-hybrid panel screening and fluorescence in situ hybridization using a biotinylated DNA probe prepared from isolated yeast artificial chromosomes. No other positive fluorescent signals were observed. This eliminates the elafin gene as a candidate gene for naevoid basal-cell carcinoma syndrome, as the gene for this syndrome localizes to chromosome 9q23.1-31. The elafin yeast artificial chromosome DNA is to be subcloned to identify polymorphic microsatellite markers that will establish whether this gene is frequently amplified in oral neoplastic tissue.

The benefits of active rewarming after cardiac operations: a randomized prospective trial

We conducted a prospective, randomized trial of three methods of rewarming patients after hypothermic cardiopulmonary bypass. Patients underwent either coronary artery bypass grafting or first-time valve replacement and were cooled to 32 degrees C during bypass. No significant differences existed among the groups as regards operative or preoperative parameters including hemodynamics and blood use. The patients actively warmed with a convective (Bair Hugger system, 3 hours) or a conductive blanket (electric overblanket, 4 hours) reached normothermia more quickly than those warmed with the space blanket (7 hours). This was reflected in significantly earlier extubation in the former two groups: Bair Hugger system 10.8 +/- 0.6 hours, electric blanket 11.3 +/- 1.0 hours, and space blanket 14.8 +/- 0.8 hours. Patients warmed with the space blanket required a higher dosage of morphine over the first 12 hours than those warmed with the electric blanket (10.4 vs 6.5 mg; p = 0.004), which may account for some of the differences between these two groups. No differences could be demonstrated between the two active blankets. On economic grounds we therefore recommend the reusable electric blanket for routine use.

The role of the vascular endothelium in the contractile responses of human chorionic plate artery in pre-eclampsia to prostaglandin F2 alpha, 5-hydroxytryptamine, and potassium chloride

This study characterises the reactivity of chorionic plate artery in pre-eclampsia to prostaglandin F2 alpha (PGF2 alpha), 5-hydroxytryptamine (5-HT), and potassium chloride (KCl) and examines the role of the vascular endothelium in these responses. Ring segments of the chorionic plate arteries of women after normal and pre-eclamptic pregnancies were contracted by PGF2 alpha, 5-HT, and KCl. The experiments were carried out in the presence and absence of endothelium, and on intact rings treated with 10(-6)M indomethacin. The maximal contractile responses of rings from pre-eclamptic women to 5-HT, PGF2 alpha, or KCl were significantly greater than those of rings from normotensive pregnant women. The EC50 values of responses were significantly lower in rings from pre-eclamptic subjects. Endothelium removal and treatment of the rings with indomethacin had no effect on the contractile responses of rings from normotensive pregnant women to all the agents, but significantly increased the EC50 value and decreased the maximal contractile responses of rings from pre-eclamptic women to 5-HT and PGF2 alpha. While de-endothelialisation increased the EC50 value for responses of the rings from pre-eclamptic women to KCl, pretreatment with indomethacin did not significantly affect the KCl-induced responses. The results of the study suggest that pre-eclampsia enhanced the reactivity of human chorionic plate artery to 5-HT, PGF2 alpha, and KCl through the involvement of endothelial derived contracting factors. The increased responses to 5-HT and PGF2 alpha were inhibited by indomethacin, but those to KCl were not.

Pregnancy-induced alterations of relaxation in response to magnesium in the rat aorta may be due to plasma-borne agents

The influence of plasma from pregnant and nonpregnant humans was examined, using magnesium-induced relaxation of precontracted rat aortic rings. The results showing magnesium-induced relaxation of aortic rings from pregnant and nonpregnant rats were compared. In rat aortic rings incubated in plasma from pregnant patients, magnesium was more potent in relaxing the precontractions induced by potassium chloride than in relaxing those induced by phenylephrine. The magnesium-induced relaxation of rings incubated in plasma from normal pregnant subjects was similar to that in unincubated rings from normal pregnant rats. Neither the removal of endothelium nor pretreatment with indomethacin affected the pattern of responses in the rings. The results suggest that the effects of pregnancy on magnesium-induced relaxation of the rat aorta may be mediated by plasma-borne agents, and the mechanisms by which the agents alter the relaxation do not involve either the vascular endothelium or prostaglandin synthesis.

Custom-made molds that prevent cement extrusion through bone defects

The success of a hip arthroplasty using a cemented femoral component relies in part on the quality of the cement technique, and is enhanced by obtaining a uniform, well-pressurized cement mantle around the prosthesis. For that reason, cortical bone defects in the femur pose technical difficulties for the surgeon planning a cemented femoral component. In this article, a new technique is presented that is used to prevent cement extrusion through defects in the femoral cortex when pressurizing the cement mantle around the prosthesis. Custom-molded polymethylmethacrylate (bone cement) plugs may be fashioned during operation to fill temporarily defects of almost any size.

An evaluation of fructosamine estimation in screening for gestational diabetes mellitus

Although persuasive arguments against routine screening for gestational diabetes mellitus (GDM) have been made, it is widely but not universally performed as a part of antenatal care. There is no international agreement on methods or criteria used for screening (or for diagnosis), and administered glucose-load methods have significant practical difficulties in a busy antenatal clinic setting. However, recent evidence supports the concept of an increased level of importance being given to a diagnosis of GDM, with interest in the fetal and neonatal origins of adult disease being added to the short-term obstetric and fetal concern during pregnancy. A second generation fructosamine test, corrected for total protein, has been evaluated as a practical alternative to glucose screening for GDM in a busy, multi-ethnic antenatal clinic. This achieved a 79.4% sensitivity and a 77.3% specificity for a diagnosis of GDM confirmed by a glucose tolerance test using Carpenter's modified criteria. In view of the organizational simplicity of this sample/test requirement, a wider evaluation is suggested together with a re-evaluation of clinical outcome criteria rather than blood glucose levels alone.

Screening for gestational diabetes in a multi-ethnic population

A multi-ethnic population was screened for gestational diabetes mellitus (GDM) using a venous plasma glucose estimation, 1 h following a standard 50 g glucose load. A significant difference in the ethnic distribution of screen-positivity was found. Amongst the screen-positive group the odds ratio (OR) for special care baby facility (SCBU) admission and birthweight > 3999 g were both increased (OR = 1.87 and 1.99). Only limited diagnostic testing by a glucose tolerance test (GTT) could be achieved for the screen-positive population. For patients with confirmed GDM (two or more abnormal values on a GTT) the OR for SCBU admission was further increased to 5.1, while the OR for increased birthweight was only 1.34. Clinical attention should be directed towards outcome assessment in order to properly evaluate the nature of and place for screening for GDM in multi-ethnic populations.

Structure and composition of the rodent lamina cribrosa

To define the architecture and extracellular matrix composition of the lamina cribrosa in rodents, normal, adult pigmented rat and guinea pig eyes were frozen and sectioned for light microscopic immunohistochemistry. Antibodies specific for collagens I, III, IV and VI, laminin, elastin, and chondroitin and dermatan sulfate proteoglycans were exposed to longitudinal and cross-sections of optic nerve heads and their binding distributions observed with the avidin-biotin-peroxidase complex technique. Cross-sections of the intraocular portion of the rat optic nerve head revealed a horizontally oval shape with distinct, vertically oriented, laminar beams. The guinea pig optic nervehead cross-section was circular, with randomly oriented beams. In both animals, collagens I, III and VI were found throughout the laminar beams, along with elastin fibrils. Collagen IV and laminin antibodies deposited along laminar beam margins and within the beams, representing astrocytic and vascular endothelial cell basement membranes. Both animals showed evidence for dermatan and chondroitin sulfate-containing proteoglycans in all connective tissue structures of the nerve head. In the rat, chondroitin-4 sulfate proteoglycans appeared localized to the sclera and laminar beams. The rat and the guinea pig optic nerve head possess an identifiable lamina cribrosa with structural proteins nearly identical to that of the primate. Both animals may provide affordable alternative animal models for in vivo studies on the role of the lamina cribrosa in glaucomatous optic nerve damage.

Genetic epidemiologic analysis of quantitative phenotypes using Gibbs sampling

We analyzed two quantitative traits (Q1 and Q2) provided in the 'Common Disease' data set with the aim of detecting both genetic and environmental determinants. We used linear regression for screening measured variables, maximum likelihood segregation and linkage analyses for detecting and localizing unmeasured genes, and Gibbs sampling for joint segregation and linkage analyses with estimation of gene-environment interaction and polygenic effects. For both Q1 and Q2, we successfully detected the unmeasured codominant major gene (MG) that was tightly linked to candidate gene C2. We also detected all of the measured variables used in generating Q1 (age, Q3, candidate gene C5) and Q2 (EF). Although our final models differed slightly from the true data generation models, our multifaceted analytic approach was successful in characterizing the determinants of Q1 and Q2.

The mechanism of relaxation in response to magnesium by the aorta of pregnant rats with salt-induced hypertension

The study examined the effect of salt-induced hypertension on vascular relaxation in response to magnesium sulphate during pregnancy. Pregnant Wistar rats were fed for 6 weeks on a diet containing 0.3% (control) and 8.0% (test) sodium chloride. Aortic rings were then removed and contracted with 10(-7) M phenylephrine or 30 mM potassium chloride. High salt intake increased the systolic blood pressure of the rats and increased the relaxation of phenylephrine-contracted intact rings in response to magnesium sulphate. Neither endothelium removal nor treatment with 10(-6) M indomethacin altered the relaxation of rings from the two groups of rats, when contracted with potassium chloride. Both processes significantly (P < 0.05) and similarly decreased the sensitivity and the maximal relaxation of rings from test rats contracted with phenylephrine; the relaxation of rings from the control rats was not altered. The results suggest that the relaxation of isolated rat aortic rings contracted with phenylephrine is enhanced in pregnant rats with salt-induced hypertension. The mechanism involved in this enhancement is dependent on the vascular endothelium and receptor activation, and is indomethacin sensitive.

Comparative advantage of 3-day food records over 24-hour recall and 5-day food frequency validated by observation of 9- and 10-year-old girls

OBJECTIVE

The validity of the 24-hour recall, 3-day food record, and 5-day food frequency was assessed to decide on a dietary assessment method for the National Heart, Lung, and Blood Institute (NHLBI) Growth and Health Study.

DESIGN

All subjects were assigned to one of three dietary assessment methods. Unobtrusive observers recorded types and amounts of foods eaten during lunch, and these were compared with the foods reported by the girls in the study.

SETTING

School lunchrooms in California and Ohio.

SUBJECTS

58 girls, aged 9 and 10 years.

MAIN OUTCOME MEASURES

Reporting errors for dietary assessment methods.

STATISTICAL ANALYSES PERFORMED

Descriptive statistics, matched pair t tests, and Spearman correlation coefficients.

RESULTS

Comparison of the intakes of energy and selected macronutrients showed different ranges of, and median percentage absolute errors for, each dietary assessment method. Percentage absolute errors ranged between 20 and 33 for the 5-day food frequency method; 19 and 39 for the 24-hour recall; and 12 and 22 for the 3-day food record. The proportion of missing foods (ie, observed food items not reported) and phantom foods (ie, reported food items not observed) by each method were 46% and 40%, respectively, for the 5-day food frequency; 30% and 33%, respectively, for the 24-hour recall; and 25% and 10%, respectively, for the 3-day food record.

APPLICATIONS/CONCLUSIONS

Errors in food reporting and quantification can vary with the type of dietary methodology. Agreement between observed and reported intakes from 3-day food records made it the best overall choice. On this basis, it was selected as the method of assessment for the NHLBI Growth and Health Study.

Obstetrical outcomes of aboriginal pregnancies at a major urban hospital

While a number of previous papers have documented the poor general health of Australia's Aboriginal population, relatively few have considered the health of Aborigines living in Australia's urban centres. In this latter instance, Aborigines have access to conventional medical services and they live in a physical environment that does not differ greatly from that experienced by the lower-class white population. Of course, racial, familial and economic differences may continue to influence differentially the perceived accessibility of services to Aborigines and their non-Aboriginal neighbours. This paper compares the pregnancy outcomes of Aboriginal women and non-Aboriginal women living in a major urban centre in Australia. The data indicate that urban Aboriginal women have adverse pregnancy outcomes at one and a half to two times the rate experienced by the non-Aboriginal population. Much of the difference can be attributed to lifestyle variations in the groups being compared.

Pregnancy outcome data in a United Arab Emirates population: what can they tell us?

A cross-sectional study of pregnancy outcome in a national Arabic population is presented to highlight a unique reproductive environment compared with many other obstetric populations. A high pro-natal intensity is evident with significant numbers of grandmultipara (36.7%) and mature gravida (22.2%). These groups did not show any significant increase in adverse antenatal or intrapartum events apart from an increasing rate of gestational diabetes with maternal age. There was an average induction/augmentation rate of 10.2% with a low rate of instrumental delivery (2.3%) and a mean caesarean section rate of 6.9%. A major antenatal complication noted was the prevalance of 17.3% for a haemoglobin < 10 g/dl together with overall increased rates of pre-existing and gestational diabetes. In addition the incidence of preterm labour increased over each of the 3 years studied and is of concern.

Grandmultiparity--not to be feared? An analysis of grandmultiparous women receiving modern antenatal care

OBJECTIVE

To document the reproductive performance of grandmultiparous women receiving modern antenatal care.

METHODS

A cross-sectional study of 2784 multiparous (882 grandmultiparous) mothers delivered in a base hospital obstetric unit staffed by western-trained midwives and consultant obstetrical staff.

RESULTS

There were minimal differences in major antenatal, peripartum and neonatal outcome events, with the exception of a high rate of gestational and pre-existing diabetes.

CONCLUSIONS

This data supports the opinion that grandmultiparity per se is not necessarily a major risk factor for either mother or fetus. Similarly, the mature grandmultigravida in this population was not at significantly increased risk of the alleged associations of increased parity and advancing maternal age, with the exception of diabetes. Together with the combined prevalence of maternal anemia this requires further investigation and probable intervention, particularly in the light of recent speculation concerning the fetal and infant origins of adult disease.

Birth weight distribution in the United Arab Emirates

Birth weight is a point measure of size, not a measure of growth and past presentation of birth weight data has confounded its use by maintaining an emphasis on size at birth rather than health at birth. This paper presents current data for a United Arab Emirates (UAE) national population for both international comparison and contrast with other Gulf populations. Unique local conditions include a high rate of diabetes in pregnancy, extreme grandmultiparity and significant numbers of mature gravida (age > 35 yrs), and emphasizes a need for a re-appraisal and redevelopment of this form of analysis as a part of the overall obstetric care of the pregnant population.

The role of extracellular calcium in pregnancy-induced attenuation of phenylephrine contraction in rat aorta with functional endothelium

The effect of pregnancy on the supply of calcium ions for the contractile responses of rat aortic rings to phenylephrine was investigated. The contractility of intact aortic rings from pregnant rats, compared with that of similar rings from non-pregnant rats, to phenylephrine and potassium chloride was significantly decreased. Contractions of rings from non-pregnant rats, pretreated with phenylephrine or potassium chloride, in response to calcium chloride were greater than those of similarly treated rings from pregnant rats. When the concentration of calcium chloride in the medium bathing the rings was reduced to 0.8 mmol.l-1, the contractile response to phenylephrine was significantly (P < 0.005) inhibited in rings from both pregnant and non-pregnant rats but to a greater extent in rings from non-pregnant rats. Contractions of aortic rings from pregnant rats in response to phenylephrine in calcium-free medium were similar to those of rings from non-pregnant rats, suggesting equal dependence on calcium from intracellular stores. The results suggest that pregnancy decreased the response to calcium influx into the aortic smooth muscle cells through both receptor- and voltage-operated calcium entry pathways. Since de-endothelialization reversed the pregnancy-induced diminished contraction to phenylephrine, it is likely that pregnancy interfered with contractions induced by activation of receptors with phenylephrine through enhanced production of endothelium-derived relaxing factor(s).

The role of endothelium in phenylephrine- and potassium-induced contractions of the rat aorta during pregnancy

The involvement of endothelium in the contractile responses of rat aortic rings to phenylephrine and potassium chloride in pregnancy was examined. Contractions in response to both agents were significantly greater in rings from non-pregnant rats than in rings from pregnant rats, and they were unaltered by treatment of the rings with indomethacin. De-endothelialization potentiated the contractions of rings from pregnant rats in response to phenylephrine, but had no significant effect on similar rings contracted with potassium chloride. Whereas de-endothelialization had no significant effect on the contractions to phenylephrine in rings from non-pregnant rats, it decreased those of rings from the same type of rats, contracted with potassium chloride. Pregnancy significantly inhibited contractions in response to calcium chloride of rings treated with phenylephrine or potassium chloride. The effect of endothelium removal on contractions to calcium chloride in rings from pregnant and non-pregnant rats treated with phenylephrine or potassium chloride was similar to that observed for phenylephrine-induced and potassium chloride-induced contractions, respectively. Contractions of intact aortic rings from pregnant and non-pregnant rats to phenylephrine in calcium-free medium were similar. Results of the study suggest that the effect of pregnancy on the contractions of the rat aorta in response to phenylephrine and potassium chloride is at least partly mediated by the endothelium and is independent of prostaglandin synthesis. The endothelial factor involved in this effect appears to modulate contractions by interfering with calcium influx through the receptor-operated calcium channels and the voltage-operated calcium channels.