Quantitative and qualitative analysis of stability for 16 serum immunoregulators over 50 freeze-thaw cycles

OBJECTIVES

To evaluate the reliability of data from the assay of bio-archived specimens, a 50-freeze-thaw-cycle (FTC) degradation study of fresh sera was conducted to test the stability of 16 immunoregulators.

METHODS

Twenty de-identified serum specimens were obtained from volunteers at United Health Services-Wilson Memorial Hospital. Specimens were stored at -20°C and underwent daily 1 h thawing and subsequent freezing for each FTC over 50 consecutive days. Immunoregulator concentrations were assessed via enzyme-linked immunosorbent assay (ELISA) in participant samples at 2 FTC (baseline), 25 FTC, and 50 FTC. Specific immunoregulators observed in the study were C-reactive protein (CRP), interleukin (IL)-1α, 4, 6, 8, 10, monocyte chemoattractant protein-1 (MCP-1, CCL2), monocyte chemoattractant protein-2 (MCP-2, CCL8), eotaxin-1, thymus-and-activation-regulated chemokine (TARC, CCL17), regulated on activation normal T-cell expressed and secreted (RANTES, CCL5), growth-regulated oncogene-alpha (GRO-α, CXCL1), small inducible cytokine A1 (I-309, CCL1), interferon-gamma (IFN-γ), interferon-gamma inducible protein-10 (IP-10, CXCL10), and tumor necrosis factor-alpha (TNF-α).

RESULTS

Quantitative stability of serum immunoregulators: Serum CRP, IL-8, IL-10, IFN-γ, IP-10, and eotaxin-1 levels appear to be statistically equivalent from baseline to 50 FTC (p ≤ .05). Retention of patterns in serum immunoregulators: patterns across FTC were retained for TARC (age) and CRP, IFN-γ, and MCP-2 (sex).

CONCLUSIONS

While the effect of multiple FTC on serum immunoregulator levels may not replicate prolonged freezer storage, the results of this study provide valuable information on the robustness of immunoregulators for research using bio-archived sera.

Impact of white-tailed deer on the spread of Borrelia burgdorferi

There is a public perception that the white-tailed deer Odocoileus virginianus (Artiodactyla: Cervidae) is the main reservoir supporting the maintenance and spread of the causative agent of Lyme disease, Borrelia burgdorferi. This study examines the pathogen prevalence rate of Borrelia in adult Ixodes scapularis (Ixodida: Ixodidae), the black-legged tick, collected from white-tailed deer and compares it with pathogen prevalence rates in adult ticks gathered by dragging vegetation in two contiguous counties west of the Hudson Valley in upstate New York. In both Broome and Chenango Counties, attached and unattached ticks harvested from white-tailed deer had significantly lower prevalences of B. burgdorferi than those collected from vegetation. No attached ticks on deer (n = 148) in either county, and only 2.4 and 7.3% of unattached ticks (n = 389) in Broome and Chenango Counties, respectively, were harbouring the pathogen. This contrasts with the finding that 40.8% of ticks in Broome County and 46.8% of ticks in Chenango County collected from vegetation harboured the pathogen. These data suggest that a mechanism in white-tailed deer may aid in clearing the pathogen from attached deer ticks, although white-tailed deer do contribute to the spatial distribution of deer tick populations and also serve as deadend host breeding sites for ticks.

Six-year follow-up of a point-source exposure to CWD contaminated venison in an Upstate New York community: risk behaviours and health outcomes 2005-2011

OBJECTIVES

It is currently unknown whether chronic wasting disease (CWD), a transmissible spongiform encephalopathy of cervids, is transmissible to humans. Reported on here are the behavioural risk factors and health conditions associated with a six-year follow-up of a known point-source exposure to a CWD infected deer in an Upstate New York community.

STUDY DESIGN

Longitudinal.

METHODS

The Oneida County Chronic Wasting Disease Surveillance Project was launched in 2005 in response to a point-source exposure to a CWD infected deer at a March 2005 Sportsmen's feast in Upstate New York. Eighty-one exposed individuals participated in the 2005 baseline data collection, and were sent follow-up questionnaires following each deer hunting season between 2005 and 2011.

RESULTS

Over a six year period, participants reported a reduction in overall venison consumption. Participants reported no significant changes in health conditions, although several conditions (vision loss, heart disease, type 2 diabetes, weight changes, hypertension, and arthritis), were significantly associated with age.

CONCLUSIONS

To this day, this incident remains the only known large-scale point-source exposure to a CWD infected deer. Prion diseases can incubate for multiple decades before the manifestation of clinical symptoms; thus, continued surveillance of this exposed study population represents a unique opportunity to assess the risk of CWD transmission to humans. This project is uniquely situated to provide the first epidemiological evidence of CWD transmission to humans, should it occur.

Aluminium in Alzheimer's disease: are we still at a crossroad?

Aluminium, an environmentally abundant non-redox trivalent cation has long been implicated in the pathogenesis of Alzheimer's disease (AD). However, the definite mechanism of aluminium toxicity in AD is not known. Evidence suggests that trace metal homeostasis plays a crucial role in the normal functioning of the brain, and any disturbance in it can exacerbate events associated with AD. The present paper reviews the scientific literature linking aluminium with AD. The focus is on aluminium levels in brain, region-specific and subcellular distribution, its relation to neurofibrillary tangles, amyloid beta, and other metals. A detailed mechanism of the role of aluminium in oxidative stress and cell death is highlighted. The importance of complex speciation chemistry of aluminium in relation to biology has been emphasized. The debatable role of aluminium in AD and the cross-talk between aluminium and genetic susceptibility are also discussed. Finally, it is concluded based on extensive literature that the neurotoxic effects of aluminium are beyond any doubt, and aluminium as a factor in AD cannot be discarded. However, whether aluminium is a sole factor in AD and whether it is a factor in all AD cases still needs to be understood.

Morphological growth and thorax dimensions among Tibetan compared to Han children, adolescents and young adults born and raised at high altitude

BACKGROUND

Studies comparing the growth of indigenous high-altitude Aymara children and children of low-altitude European descent who have been born and raised at high altitude in the Andes have provided evidence for genetically-determined differences in thorax growth, as well as for population differences in height, weight and other measures of overall size. Comparable studies now can be undertaken in Asia because of the growing number of Han Chinese who have been born and raised at high altitude on the Qinghai-Tibetan Plateau.

AIM

The study compares the growth of indigenous Tibetan children and children of Han descent who have been born and raised at the same high altitudes, and under similar socio-economic conditions.

SUBJECTS AND METHODS

Measurements of stature, sitting height, weight, triceps and subscapular skinfolds, upper arm muscle area, transverse chest diameter, anterio-posterior chest diameter, and chest circumference were taken on 1439 Tibetan and Han males and females between the ages of 6 and 29 years who were born and raised 3200 m, 3800 m or at 4300 m in the high altitude province of Qinghai in western China.

RESULTS

Han-Tibetan differences in body size do not occur systematically for any measurement, for any age group, or for either gender; nor is there a systematic pattern of body size differences between 3200 m and 4300 m. This indicates that there are no differences in general growth between the two groups at high altitude in Qinghai, although both groups grow more slowly than urban children at low altitude in China. On the other hand, Tibetan males possess significantly deeper chests than Han males, and Tibetan females possess significantly wider chests than Han females. Tibetans of both sexes possess significantly larger chest circumferences than Han males and females.

CONCLUSIONS

Although genetic similarities cannot be ruled out, comparable dietary stress is a likely explanation for the similar and slow morphological growth of Han and Tibetans at high altitude. However, Han-Tibetan differences in thorax dimensions are likely a consequence of population (genetic) differences in the response to hypoxia during growth.

ALS and PDC of Guam: forty-year follow-up

BACKGROUND

It was noticed in the mid-1950s that the incidence of ALS and parkinsonism--dementia complex (PDC) were much higher on Guam than anywhere else in the world. In 1958, a registry of patients and controls was established to ascertain the familial and genetic aspects of these diseases. Patients and individually matched controls and their relatives were registered from 1958 to 1963. The registry was updated and analyzed in 1998 through 1999.

OBJECTIVE

To ascertain whether first-degree relatives of patients had a higher risk for developing ALS or PDC than relatives of controls.

METHODS

During the period of 1958 to 1963, 126 new patients and 126 individually matched controls and their respective first-degree relatives and spouses were evaluated neurologically and registered. Forty years later, the number of new cases among the patient and control relatives were compared to an expected number of new cases based on the age- and sex-specific incidence of ALS and PDC in the population at large.

RESULTS

From 1958 to 1999, there were 102 new ALS or PDC cases among relatives of patients and 33 among relatives of controls. These values were compared with the derived expected values. There were more observed than expected new cases among patients' relatives, and less observed cases than expected among the controls' relatives.

CONCLUSIONS

Relatives of patients with ALS or PDC have significantly higher risks for developing the disease than the Guamanian population, whereas relatives of controls have significantly lower risks.

TAU as a susceptibility gene for amyotropic lateral sclerosis-parkinsonism dementia complex of Guam

BACKGROUND

A Guam variant of amyotrophic lateral sclerosis (ALS-G) and parkinsonism dementia complex (PDC-G) are found in the Chamorro people of Guam. Both disorders have overlapping neuropathologic findings, with neurofibrillary tangles in spinal cord and brain. The cause of ALS-G-PDC-G is unknown, although inheritance and environment appear important. Because neurofibrillary tangles containing tau protein are present in ALS-G-PDC-G, and because mutations in the tau gene (TAU) cause autosomal dominant frontotemporal dementia, TAU was examined as a candidate gene for ALS-G-PDC-G.

METHODS

TAU was evaluated by DNA sequence analysis in subjects with ALS-G-PDC-G, by linkage analysis of TAU polymorphisms in an extended pedigree from the village of Umatac, and by evaluation of linkage disequilibrium with polymorphic markers flanking and within TAU.

RESULTS

Linkage disequilibrium between ALS-G-PDC-G and the TAU polymorphism CA3662 was observed. For this 2-allele system, PDC and ALS cases were significantly less likely than Guamanian controls to have the 1 allele (4.9% and 2% vs 11.5%, respectively; Fisher exact P =.007). DNA sequence analysis of TAU coding regions did not demonstrate a mutation responsible for ALS-G-PDC-G. Analysis of TAU genotypes in an extended pedigree of subjects from Umatac showed obligate recombinants between TAU and ALS-G-PDC-G. Linkage analysis of the Umatac pedigree indicates that TAU is not the major gene for ALS-G-PDC-G.

CONCLUSIONS

The genetic association between ALS-G-PDC-G implicates TAU in the genetic susceptibility to ALS-G-PDC-G. TAU may be a modifying gene increasing risk for ALS-G-PDC-G in the presence of another, as yet, unidentified gene.

Increased susceptibility to Kuru of carriers of the PRNP 129 methionine/methionine genotype

Kuru reached epidemic proportions by the mid-twentieth century among the Fore people of New Guinea and disappeared after the abolition of cannibalistic rituals. To determine susceptibility to kuru and its role in the spread and elimination of the epidemic, we analyzed the PRNP gene coding sequences in 5 kuru patients; no germline mutations were found. Analysis of the PRNP 129 methionine (M)/valine (V) polymorphism in 80 patients and 95 unaffected controls demonstrated that the kuru epidemic preferentially affected individuals with the M/M genotype. A higher representation of M/M carriers was observed among the affected young Fore males entering the age of risk, whereas a lower frequency of M/M homozygotes was found among the survivors. M/V and V/V genotypes predisposed to a lower risk of disease development and longer incubation times. These findings are relevant to the current outbreak of variant Creutzfeldt-Jakob disease (vCJD) in the United Kingdom, because all vCJD patients tested thus far have been M/M carriers.

Human adaptability research into the beginning of the third millennium

Human adaptability, as a field of inquiry within human biology, became defined during the research activities of the International Biological Program (IBP) (1964-1974). During this period, research was focused on ecological, physiological, and genetic studies of human populations within the theoretical frameworks of adaptation and evolution. Other defining characteristics of the IBP human adaptability research were standardization of methods, multidisciplinary projects, international cooperation, and a concern with human health issues. Some observers suggest that this research contributed to the ongoing transformation of physical anthropology and related fields from a largely descriptive to an analytical science. During the 25 years between the end of the IBP and the present, a number of research trends have continued: Several new multidisciplinary projects were initiated and completed; a subfield of demography within human biology has matured; nutrition, infant and child growth, and health studies have proliferated; and molecular genetics and DNA analysis have superseded the earlier population genetics. International programs today are geared toward more practical and applied studies with less emphasis on basic science. Continuation of human adaptability research into the 21st century is likely to make contributions in 3 broad areas: population, environment, and health. Productive research is likely to contribute to these 3 areas in the following categories: reproduction, psychosocial stress, life span approaches to health, effects of losses in biodiversity on health, a human biology of poverty, emerging infectious diseases, epidemiology of modernization, evolutionary medicine, and aging. The success of much of this research in its contribution to knowledge will come from the integrated perspectives of a biobehavioral framework of inquiry.

Growth of Qinghai Tibetans living at three different high altitudes

This study compares the stature, weight, skinfolds, upper arm muscle area, and chest dimensions of Tibetan children, adolescents, and young adults who were born and raised, or who had lived from infancy, at 3,200 m, 3,800 m, and 4,300 m in Qinghai Province, People's Republic of China. While the individuals measured in Qinghai are among the tallest and heaviest Tibetans reported in the literature, they are nevertheless smaller and lighter than well-off children living at low altitude. The pattern of size variation among Tibetan males and females measured at the three high altitudes, along with evidence of a secular trend at 4,300 m, suggests that nutrition may significantly effect growth at high altitude. Only minor differences in thorax dimensions exist between Tibetan males and females measured at 3,200 m and 3,800 m. However, Tibetan males at 4,300 m possess slightly narrower and deeper chests (during and after adolescence) than males at 3,200 m and 3,800 m. Since individuals from 3,800 m and 4,300 m belong to the same local populations, this characteristic is unlikely to be genetically determined. However, it may be related to differences in the degree of hypoxia or to the influences of other environmental conditions.

Natural experimental models: the global search for biomedical paradigms among traditional, modernizing, and modern populations

During the past four decades, biomedical scientists have slowly begun to recognize the unique opportunities for studying biomedical processes, disease etiology, and mechanisms of pathogenesis in populations with unusual genetic structures, physiological characteristics, focal endemic disease, or special circumstances. Such populations greatly extend our research capabilities and provide a natural laboratory for studying relationships among biobehavioral, genetic, and ecological processes that are involved in the development of disease. The models presented illustrate three different types of natural experiments: those occurring in traditionally living, modernizing, and modern populations. The examples are drawn from current research that involves population mechanisms of adaptation among East African Turkana pastoralists; a search for etiology and mechanisms of pathogenesis of an emerging disease among the Yakut people of Siberia; and psychosocial stress, hypertension, and cardiovascular disease in women working outside the home in New York City and among subpopulations in Hawaii. The models in general, and the examples in specific, represent natural laboratories in which relatively small intrapopulation differences and large interpopulation differences can be used to evaluate health and disease outcomes.

Tau is a candidate gene for chromosome 17 frontotemporal dementia

Frontotemporal dementia with parkinsonism, chromosome 17 type (FTDP-17), a recently defined disease entity, is clinically characterized by personality changes sometimes associated with psychosis, hyperorality, and diminished speech output, disturbed executive function and nonfluent aphasia, bradykinesia, and rigidity. Neuropathological changes include frontotemporal atrophy often associated with atrophy of the basal ganglia, substantia nigra, and amygdala. Neurofibrillary tangles (NFTs) are seen in some but not all families. Inheritance is autosomal dominant and the gene has been regionally localized to 17q21-22 in a 2- to 4-centimorgan (cM) region flanked by markers D17S800 and D17S791. The gene for tau, the primary component of NFTs, is located in the same region of chromosome 17. Tau was evaluated as a candidate gene. Physical mapping studies place tau within 2 megabases or less of D17S791, but it is probably outside the D17S800-D17S791 FTDP-17 interval. DNA sequence analysis of tau coding regions in affected subjects from two FTDP-17 families revealed nine DNA sequence variants, eight of which were also identified in controls and are thus polymorphisms. A ninth variant (Val279Met) was found in one FTDP-17 family but not in the second FTDP-17 family. Three lines of evidence indicate that the Val279Met change is an FTDP-17 causative mutation. First, the mutation site is highly conserved, and a normal valine is found at this position in all three tau interrepeat sequences and in other microtubule associated protein tau homologues. Second, the mutation co-segregates with the disease in family A. Third, the mutation is not found in normal controls.

Slow dendritic transport of dissociated mouse hippocampal neurons exposed to aluminum

We determined the influence of aluminum on dendritic transport, using an in vitro system of dissociated mouse hippocampal neurons. Newly synthesized RNA from dissociated mouse hippocampal neurons was more slowly transported into dendrites in the presence of aluminum chloride when compared to those without the addition of aluminum chloride to the culture medium. Suppression of dendritic transport of newly synthesized RNA may be responsible for the dendritic degeneration observed in aluminum neurotoxicity, eventually leading to neuronal degeneration.

Maltol (3-hydroxy-2-methyl-4-pyrone) toxicity in neuroblastoma cell lines and primary murine fetal hippocampal neuronal cultures

Maltol (3-hydroxy-2-methyl-4-pyrone), a product of carbohydrate degradation, is known to enhance aluminium-induced neurofibrillary degeneration in neuronal systems, but few toxicological studies have been conducted. We report maltol toxicity in neuroblastoma cell lines of mouse (Neuro 2a) and human (IMR 32) origin, and in primary murine fetal hippocampal neuronal cultures. As determined by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2 -(4-sulfophenyl)-2H-tetrazolium, inner salt] conversion, maltol exhibited a dose-dependent toxicity on the viability of both neuroblastoma cell lines, but the toxicity was more pronounced in Neuro 2a cells. Maltol was also toxic in a dose-dependent manner in primary murine fetal hippocampal neurons at micromolar concentrations. Electrophoresis of DNA extracted from maltol-intoxicated cells showed a laddering pattern, suggestive of apoptotic cell death. In the maltol-exposed hippocampal neuronal cultures, fragmented DNA ends were visualized in situ in morphologically condensed nuclei by terminal deoxynucleotidyl transferase with digoxigenin-labelled UTP and subsequent immunohistochemistry. Collectively, our findings suggest that the toxic effect of maltol is mediated through apoptosis. Further toxicological investigations are warranted, since maltol is found in the daily diet of humans.

Comparative study of chronic aluminum-induced neurofilamentous aggregates with intracytoplasmic inclusions of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is characterized neuropathologically by chromatolysis, Bunina bodies, hyaline inclusions, skein-like inclusions and axonal spheroids. Aluminum, a known neurotoxin, is the cause of dialysis encephalopathy and is considered to be a causative agent in high incidence foci of ALS in the western Pacific. We have developed an experimental model of motor neuron degeneration in New Zealand white rabbits using chronic low-dose intracisternal administration of aluminum and compared the clinical and neuropathological changes to those of human ALS. Aluminum-inoculated rabbits developed progressive hyperreflexia, hypertonia, limb splaying, gait impairment, muscle wasting, hindlimb paralysis and impaired tonic immobility responses without overt encephalopathic features over a 14-month period. Examination of spinal cords from these animals demonstrated the frequent occurrence and progressive development of anterior horn cell lesions that included small, round, argentophilic perikaryal inclusions similar to hyaline inclusions seen in human ALS. Other inclusions were more condensed and eosinophilic, while still others had neurofibrillary tangle-like morphologies. Axonal spheroids and neuritic thickenings were also prominent and were identical to those seen in human ALS. We believe that the similar and progressive development of neuropathological changes observed in the chronic aluminum-intoxication model, compared to human ALS, warrants further study to aid in understanding the cellular and molecular mechanisms of human motor neuron disease.

Can the mechanisms of aluminum neurotoxicity be integrated into a unified scheme?

Regardless of the host, the route of administration, or the speciation, aluminum is a potent neurotoxicant. In the young adult or developmentally mature host, the neuronal response to Al exposure can be dichotomized on morphological grounds. In one, intraneuronal neurofilamentous aggregates are formed, whereas in the other, significant neurochemical and neurophysiological perturbations are induced without neurofilamentous aggregate formation. Evidence is presented that the induction of neurofilamentous aggregates is a consequence of alterations in the posttranslational processing of neurofilament (NF), particularly with regard to phosphorylation state. Although Al has been reported to impact on gene expression, this does not appear to be critical to the induction of cytoskeletal pathology. In hosts responding to Al exposure without the induction of cytoskeletal pathology, impairments in glucose utilization, agonist-stimulated inositol phosphate accumulation, free radical-mediated cytotoxicity, lipid peroxidation, reduced cholinergic function, and altered protein phosphorylation have been described. The extent to which these neurochemical modifications correlate with the induction of a characteristic neurobehavioral state is unknown. In addition to these paradigms, Al is toxic in the immediate postnatal interval. Whether unique mechanisms of toxicity are involved during development remains to be determined. In this article, the mechanisms of Al neurotoxicity are reviewed and recommendations are put forth with regard to future research. Primary among these is the determination of the molecular site of Al toxicity, and whether this is based on Al substitution for divalent metals in a number of biological processes. Encompassed within this is the need to further understand the genesis of host- and developmental-specific responses.

Analysis of the neurotoxic plasticizer n-butylbenzenesulfonamide by gas chromatography combined with accurate mass selected ion monitoring

The plasticizer, n-butylbenzenesulfonamide (NBBS), is reported to be neurotoxic when inoculated intracisternally or intraperitoneally into rabbits. Because NBBS is commonly used in the production of polyamide (nylon) plastics and is soluble in water, the disposal of NBBS-containing plastics in landfill sites could result in NBBS appearing in the leachate. Further, NBBS could also be leached from packaging into their contents. To allow us to examine the risks posed by NBBS in the environment, we have developed a quantitative assay for this compound. The assay employs a one-step extraction into dichloromethane followed by gas chromatography with accurate mass selected ion recording. The assay incorporates [13C6]NBBS as an internal standard to allow precise quantitation, and four separate ion chromatograms are recorded. NBBS was found in some Australian domestic solidwaste landfill leachate (from less than 0.3 to 94.6 ng/mL), but ground water in the vicinity of a landfill had only trace quantities of NBBS. NBBS was also quantitated in some bottled and cask wines, and levels varied from not detected to 2.17 ng/mL (n = 14). Additional studies are required to assess the public health risks associated with the use of NBBS as a plasticizer.

Dose-dependent selective suppression of light (NFL) and medium (NFM) but not heavy (NFH) molecular weight neurofilament mRNA levels in acute aluminum neurotoxicity

We inoculated 5- to 6-week old New Zealand white rabbits intracisternally with either 100, 250, 500, 750, or 1000 micrograms of AlCl3 or 0.9% NaCl and correlated the extent of cervical motor neuron neurofilamentous inclusion formation at 48 h postinoculation with alterations in neurofilament (NF) mRNA levels. RNA was isolated from cervical spinal cord by the guanidine isothiocyanate method and individual RNA samples were normalized for poly(A+) content. Northern blot analysis was performed with cDNA probes for light (NFL), medium (NFM), and heavy (NFH) neurofilament subunit protein or with oligonucleotide probes for alpha-tubulin or actin. No significant alteration in the levels of alpha-tubulin, actin, or NFH mRNA were observed, regardless of the aluminum dose. In contrast, dose-dependent reductions in NFL and NFM mRNA levels occurred in direct proportion to the extent of neurofilamentous inclusion formation. While inoculums of NaCl or 100 or 250 micrograms AlCl3 induced neither inclusion formation or alterations in mRNA levels, both inclusion formation and reductions in the levels of NFL and NFM mRNA occurred thereafter, becoming maximal with inoculums of 1000 micrograms AlCl3. These experiments indicate that intracisternally administered AlCl3 acutely suppresses NFL and NFM mRNA levels without affecting those of NFH. This pattern is in distinct contrast to the uniform reductions of all NF mRNA transcript levels during neurogenesis or following axotomy, indicating a specific effect of aluminum upon steady-state levels of NF mRNA that correlates with the induction of neurofilamentous aggregates.

The Cu/Zn superoxide dismutase gene in ALS and parkinsonism-dementia of Guam

Guam is one of three endemic foci whose indigenous (Chamorro) people have an unusually high incidence of fatal neurodegenerative disorders, amyotrophic lateral sclerosis (ALS) and Parkinsonism-dementia (PD). Recently, mutations in the Cu/Zn superoxide dismutase (SOD-1) gene have been identified in some familial cases of ALS. To investigate if mutations in the SOD-1 gene are also involved in the pathogenesis of ALS and PD of Guam, we analyzed the SOD-1 gene in Chamorros. No mutations were found in Chamorros with ALS or PD, indicating that mutations in the SOD-1 gene do not underlie the high-incidence neurodegenerative disorders of Guam.

Neurofibrillary tangles of Guamanian amyotrophic lateral sclerosis, parkinsonism-dementia and neurologically normal Guamanians contain a 4- to 4.5-kilodalton protein which is immunoreactive to anti-amyloid beta/A4-protein antibodies

Neurofibrillary tangles (NFT), one of the neurodegenerative features of Alzheimer's disease, Down's syndrome and normal aging, is a constant, widespread neuropathological finding in Guamanian amyotrophic lateral sclerosis (ALS), parkinsonism-dementia (PD) and in neurologically normal Guamanians, dying of causes other than ALS and PD. NFT in brain tissue sections of patients with Guamanian ALS and PD were immunoreactive to antibodies directed against a 43-amino acid synthetic peptide homologous to amyloid beta/A4-protein (anti-SP43) associated with Alzheimer's disease. NFT extracted from frozen brain tissues of Guamanian patients with ALS and PD and from tissues of neurologically normal Guamanians were congophilic and birefringent. By negative-stain electron microscopy, NFT preparations contained bundles and/or isolated single, straight, unpaired filaments in Guamanian ALS and occasionally pairing of filaments in neurologically normal Guamanians, measuring 5-20 nm in diameter. Formic acid digestion of NFT preparations, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion high-pressure liquid chromatography, showed a protein with an apparent molecular mass of 4- to 4.5-kDa, which by Western blot analysis was immunoreactive to anti-SP43. Immunoabsorption of purified NFT or SP43 with anti-SP43 abolished immunostaining. Our study corroborate previous data that amyloid beta/A4-protein is present in NFT in Guamanian PD. Furthermore, our data indicate that amyloid beta/A4-protein is present in NFT in brain tissues of patients with Guamanian ALS and in neurologically normal Guamanians, suggesting a common mechanism of amyloidogenesis with NFT formation in Alzheimer's disease and normal brain aging.

Rare neuropil threads in amyotrophic lateral sclerosis and parkinsonism-dementia on Guam and in the Kii Peninsula of Japan

Using three different silver impregnation methods and antisera against microtubule-associated protein-tau (MAP-tau) and amyloid beta/A4 protein, we demonstrated abundant neurofibrillary tangles (NFTs), rare senile plaques, absence of amyloid angiopathy and rare MAP-tau- and silver-positive neuropil threads in the hippocampus of patients with amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) on Guam and in the Kii Peninsula of Japan. In contrast, abundant neuropil threads, NFTs, senile plaques with associated dystrophic neurites and amyloid angiopathy were confirmed in Alzheimer disease patients. These observations indicate that there may be important factor(s) responsible for the difference in the deposition and distribution of amyloid beta/A4 protein and MAP-tau between Pacific ALS and PD and Alzheimer disease.

Potential role of an additive genetic component in the cause of amyotrophic lateral sclerosis and parkinsonism-dementia in the western Pacific

Amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) are neurological degenerative disorders that occur in three high incidence foci in the western Pacific: among the Chamorros of Guam and the Commonwealth of the Northern Marianas Islands, among Japanese on the Kii peninsula of Honshu Island, and among the Auyu and Jakai peoples of southern West New Guinea. Previous studies have implicated both genetic susceptibility and environmental risk factors in the causation and familial clustering of these disorders. The data analyzed consist of 2,026 individuals in nuclear families ascertained on Guam through two mechanisms: (1) nuclear families were included in the study if one or both parents in the family were affected with ALS or PD or both; and (2) a group of "controls" was selected by obtaining nuclear families where neither parent was affected and both had lived through the age of risk. Clinically, ALS and PD are two distinct disorders. However, preliminary analyses indicated that combining all three diagnoses into one affected diagnosis for genetic analyses (thereby assuming any genetic effect on susceptibility to the two disorders was due to the same genetic mechanism) was reasonable. An age, sex and birth cohort-specific liability was defined and segregation analysis was performed under both logistic and normal models for this liability at the time of disease onset. Under either model, purely environmental, Mendelian dominant and Mendelian recessive hypotheses could be rejected, but a two-allele additive major locus hypothesis could not be rejected.

Immunocytochemical and ultrastructural evidence of dendritic degeneration in motor neurons of aluminum-intoxicated rabbits

Using immunocytochemical and ultrastructural methods, we observed extensive and characteristic dendritic changes in motor neurons of rabbits inoculated intracisternally with aluminum phosphate. Anti-microtubule-associated protein 2 immunostaining revealed markedly reduced immunoreactivity in motor neuron dendrites and a reduced number of dendritic trees in aluminum phosphate-intoxicated rabbits. These dendritic changes were confirmed at the ultrastructural level; neurofilamentous accumulations, membranous inclusions and disrupted microtubules were common features of motor neuron axons. These observations suggest that dendrites are characteristically involved in aluminum intoxication in addition to the widely reported accumulation of phosphorylated neurofilament in perikarya and axons.

Failure to isolate human T cell lymphotropic virus type I and to detect variant-specific genomic sequences by polymerase chain reaction in Melanesians with indeterminate western immunoblot

The controversy over the endemicity of human T cell lymphotropic virus type I (HTLV-I) in Melanesia has been settled recently by the isolation of genetically distinct, highly divergent sequence variants of HTLV-I from unrelated inhabitants of Papua New Guinea and the Solomon Islands. Still at issue, however, is the significance of the high frequency of indeterminate HTLV-I Western blots (defined as reactivity to only gag-encoded proteins) among Melanesians. To investigate whether this indeterminate seroreactivity reflects specific reactivity to the Melanesian HTLV-I variants, 27 seroindeterminate Melanesians from Papua New Guinea and the Solomon Islands were studied for evidence of HTLV-I infection. Although antibodies against Melanesian variant-specific env gene products and variant-specific env gene sequences were detected by Western blot analysis and polymerase chain reaction, respectively, in all 11 HTLV-I Western blot-positive Melanesians, none of the 27 seroindeterminate Melanesians had such variant-specific antibodies or HTLV-I proviral sequences. In addition, attempts to isolate HTLV-I from seroindeterminate individuals were unsuccessful. These data indicate that HTLV-I infection is not the cause of the indeterminate Western blot reactivity seen in Melanesia.

Thiamin mono- and pyrophosphatase activities from brain homogenate of Guamanian amyotrophic lateral sclerosis and parkinsonism-dementia patients

Thiamin-pyrophosphatase (TPPase) and thiamin-monophosphatase (TMPase) were determined using a spectrophotometric method at various pH values (5.5, 7.5, and 9.0) in brain tissue obtained at autopsy from amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) patients from Guam and from Guamanian patients who died from other diseases (controls). TPPase separation by thin-layer polyacrylamide gel isoelectric focusing (IEF) was also performed using both gray and white matter. TPPase content, chemically determined at pH 9.0, was found to be significantly reduced in the frontal cortex of ALS and PD patients compared to controls. TMPase content, on the contrary, was unchanged. IEF analysis showed 9 clear-cut bands with TPPase activity in the pH range 5.4-7.2 and a broad band at pH 4.7-5.2. The enzymatic activity was higher in gray than in white matter. In one patient the pattern was clearly different, with two additional bands observed at pH 7.1 and 6.7, and thought to be due to genetic microheterogeneity.

Aluminum decreases the zinc concentration of soft tissues and bones of rats fed a low calcium-magnesium diet

The relationship between magnesium (Mg) and zinc (Zn) in soft tissues and bone of rats was studied after administration of unbalanced mineral diets. Minerals and metals in soft tissues and bone were determined using inductively coupled plasma emission spectrometry (ICP). There were significant positive correlations between serum Zn and Mg levels, between serum Zn and Zn content of soft tissues and bone, and between serum Mg levels and Zn content of bone and soft tissues in rats fed unbalanced mineral diets. A significant positive correlation was also found between Zn and Mg content in the lumbar spine and femoral bone of rats. It appears that altered bone mineralization induced by unbalanced mineral diets leads to mobilization of Mg and Zn from rat bones in similar ways.

Highly divergent molecular variants of human T-lymphotropic virus type I from isolated populations in Papua New Guinea and the Solomon Islands

To determine the molecular genetic relationship between Melanesian strains of human T-lymphotropic virus type I (HTLV-I) and cosmopolitan prototype HTLV-I, we amplified by PCR, then cloned, and sequenced a 522-base-pair region of the HTLV-I env gene in DNA extracted from uncultured (fresh) and cultured peripheral blood mononuclear cells obtained from six seropositive Melanesian Papua New Guineans and Solomon Islanders, including a Solomon Islander with HTLV-I myeloneuropathy. Unlike isolates of HTLV-I from Japan, the West Indies, the Americas, and Africa, which share greater than or equal to 97% sequence homology, the Melanesian strains of HTLV-I were only 91.8%-92.5% identical with a prototype Japanese HTLV-IATK-1. The nucleotide sequence of proviral DNA from the Solomon Islander with HTLV-I myeloneuropathy also diverged markedly from that of HTLV-I isolated from Japanese patients with HTLV-I-associated myelopathy and from Jamaican patients with tropical spastic paraparesis, suggesting that these variant viruses are capable of causing disease. The HTLV-I variants from Papua New Guineans, in turn, differed by nearly 4% from the Melanesian variants from Solomon Islanders, indicating the existence of another HTLV-I quasi-species. By contrast, HTLV-I strains from two residents of Bellona Island, a Polynesian Outlier within the Solomon Islands, were closely related to cosmopolitan prototype HTLV-I (greater than or equal to 97% sequence identity), suggesting recent introduction, possibly during this century. These findings are consistent with a proto-Melanesian HTLV-I strain of archaic presence, which evolved independently of contemporary cosmopolitan strains, and pose new questions about the origin and global dissemination of HTLV-I.

Chronic aluminum-induced motor neuron degeneration: clinical, neuropathological and molecular biological aspects

The monthly intracisternal inoculation of young adult New Zealand white rabbits with low-dose (100 micrograms) aluminum chloride induces aggregates of phosphorylated neurofilament that mimics the intraneuronal inclusions of amyotrophic lateral sclerosis. The chronic progressive myelopathy and topographically-specific motor neuron degeneration that occurs in the absence of suppressions of neurofilament messenger RNA levels in this model contrasts with the acute fulminant encephalomyelopathy and nonspecific gene suppressions that occur subsequent to high-dose (1000 micrograms) aluminum chloride inoculations. Further analysis of this unique model of chronic motor system degeneration can be expected to provide additional insights into the pathogenesis of amyotrophic lateral sclerosis.

Neuron-specific thresholds of aluminum toxicity in vitro. A comparative analysis of dissociated fetal rabbit hippocampal and motor neuron-enriched cultures

Mature dissociated motor neuron-enriched and hippocampal neuron cultures derived from fetal New Zealand white rabbits were continuously exposed to 1, 10, 25, 50, or 100 microM AlCl3 in a chemically defined medium for 14 days. Motor neuron-enriched cultures exposed to low concentrations (1 or 10 microM) of AlCl3 remained viable for the entire experiment but developed perikaryal and neuritic inclusions composed of phosphorylated neurofilament. Similar inclusions developed in cultures exposed to 25 and 50 microM AlCl3, but motor neurons did not survive beyond 10 days exposure. The 100 microM AlCl3-supplemented medium induced cell death within 72 hours without development of inclusions. In contrast, hippocampal neurons exposed to 1, 10, or 25 microM AlCl3 developed no morphological changes or inclusions. Although hippocampal cultures exposed to 50 or 100 microM AlCl3 developed perinuclear and proximal neuritic inclusions of phosphorylated neurofilament after 10 days, they remained viable. These in vitro morphological observations demonstrate a 10-fold greater sensitivity of spinal motor neurons to aluminum toxicity when compared with hippocampal neurons and suggest that the earlier observations of neuron-specific thresholds of aluminum toxicity in vivo are related to unique regulatory mechanisms of neurofilament biosynthesis and catabolism within distinct neuronal cell populations.

Prevalence of human T-cell lymphotropic virus type I infection in Singapore: a preliminary report

Human T-cell lymphotropic virus type I (HTLV-I) infection is endemic in southwestern Japan, the Caribbean basin, Colombia, Africa and in several isolated populations in Papua New Guinea, the Solomon Islands and Vanuatu. To determine the seroprevalence of HTLV-I infection in Singapore, we tested sera from 115 hospitalized patients with acute nephritis, 50 patients with suspected leptospirosis, 34 patients with non-A, non-B hepatitis, and from 28 healthy volunteers for IgG antibodies against HTLV-I using an enzyme-linked immunosorbent assay. Antibodies were detected in sera from 6 of the 199 patients and from 3 of the 28 healthy volunteers, but these positives could not be confirmed by Western immunoblotting. Our data are consistent with other reports of low seroprevalence of HTLV-I infection despite extensive Japanese contact in Korea, Taiwan, the People's Republic of China and Micronesia. Further studies on a larger sample size, however, are necessary to confirm the absence of any focus of infection in the Singapore population.

Verification of HTLV-I infection in the Solomon Islands by virus isolation and gene amplification

We report the detection of human T-lymphotropic virus type I (HTLV-I) genomic sequences by polymerase chain reaction in lymphocyte cultures of three unrelated native Solomon Islanders, including a patient with HTLV-I myeloneuropathy, residing in widely separated regions. In addition, we have isolated HTLV-I from T-cell lines derived from two of these individuals. Virus-specific proteins of 15, 19, 24, 46 and 53 kilodaltons were detected by immunofluorescence and Western immunoblot, using serum from a Colombian patient with HTLV-I myeloneuropathy, sera from HTLV-I-infected rabbits, and monoclonal and polyclonal antibodies against HTLV-I gag and env gene products. Amplification of HTLV-I gag, pol and env sequences by polymerase chain reaction confirmed that the viral isolates were HTLV-I, not HTLV-II. Our data clearly demonstrate that HTLV-I does exist in Melanesia. Although the Solomon Islands viral isolates resemble prototype strains of HTLV-I, we believe they represent variants of HTLV-I, particularly in the light of our recent isolation of an HTLV-I variant from Papua New Guinea. Nucleotide sequence analysis of these viral strains, now in progress, should clarify the molecular epidemiology and phylogeny of HTLV-I.

Human T-lymphotropic virus type I infection in the Solomon Islands

To ascertain the prevalence of human T-lymphotropic virus type I (HTLV-I) infection and the occurrence of diseases caused by HTLV-I in the Solomon Islands, we tested 1141 sera from 851 patients (317 females and 534 males), who were hospitalized at the Central Hospital in Honiara between February 1984 and November 1988, for antibodies to HTLV-I using an enzyme-linked immunosorbent assay (ELISA). Sera from 69 of 81 ELISA-positive patients and from 56 ELISA-negative patients were then tested by Western analysis. As verified by strict Western immunoblot criteria, the overall HTLV-I seroprevalence was 2.2% (19/851). Age- and gender-specific prevalence data indicated an age-related acquisition of infection with no sexual predominance. No diagnosis category was over-represented among the seropositive patients. HTLV-I-specific antibodies were found in serum and cerebrospinal fluid samples from one of six patients with spastic paraparesis. As in other Melanesian populations, the majority of ELISA-positive sera could not be confirmed by Western analysis. Reactivity to three or more gag-encoded proteins was found in 85% (45/53) of ELISA-positive, Western blot-indeterminate sera, and 30% (16/53) reacted to p19 and an env gene product but lacked reactivity to p24. Whether or not the high frequency of indeterminate HTLV-I Western immunoblots in the Solomon Islands is indicative of incomplete specific reactivity to HTLV-I or the existence of antigenically related retroviruses is being investigated.

N-butyl benzenesulfonamide: a neurotoxic plasticizer inducing a spastic myelopathy in rabbits

N-Butyl benzenesulfonamide (NBBS), a plasticizer used commercially in the polymerization of polyamide compounds, is neurotoxic. Young adult New Zealand white rabbits, inoculated repeatedly with NBBS by the intracisternal or intraperitoneal routes, developed a dose-dependent motor dysfunction characterized by limb splaying, hyperreflexia, hypertonia, gait impairment, and abnormal righting reflexes. Histopathological changes consisted of intramedullary thickening of the ventral horn axons, random neuroaxonal spheroids confined to brain stem nuclei and spinal motor neurons, and swollen dendritic processes of spinal motor neurons. Immunoreactivity to a monoclonal antibody against microtubule-associated protein-2 (MAP-2) was markedly increased in the dendrites of spinal motor neurons following thrice weekly intraperitoneal inoculations of NBBS for 4 months, whereas after 12 monthly intracisternal inoculations, MAP-2 immunoreactivity was absent or strikingly reduced in the same neuronal populations. Ultrastructurally, postsynaptic zones contained vacuoles and multilamellar bodies. These findings raise questions about the safety of NBBS to humans.

Human T lymphotropic virus type I infection in Papua New Guinea: high prevalence among the Hagahai confirmed by western analysis

A serologic survey for human T lymphotropic virus type I (HTLV-I) infection was conducted on nearly half of the entire 260-member Hagahai population, a hunter-horticulturist group occupying the northern banks of the Yuat River Gorge in Madang Province of Papua New Guinea. For comparison, sera from two neighboring groups, the Pinai and Haruai, were tested. As determined by enzyme-linked immunosorbent assay (ELISA) and verified by Western immunoblot, IgG antibodies against HTLV-I were detected in 17 of 120 Hagahai, giving an HTLV-I seroprevalence of 14%, which is as high as that found in HTLV-I-endemic regions such as southwestern Japan and the Caribbean basin. Infection tended to cluster in family groups and was more common with increasing age. The majority of ELISA-positive (45/61) Hagahai sera were indeterminate, with 62% (28/45) exhibiting reactivity to three or more gag-encoded proteins. The clinical significance of the high frequency of indeterminate HTLV-I Western immunoblots is unknown, but it is not unlike that encountered in other Melanesian populations. Whether this reflects incomplete specific reactivity to HTLV-I or the existence of HTLV-I-related retroviruses in Papua New Guinea is being investigated.

The temporal expression of amyloid precursor protein mRNA in vitro in dissociated hippocampal neuron cultures

The subunit protein of the neurofibrillary tangle, the core protein of the neuritic plaque, and the amyloid of the cerebrovasculature in Alzheimer disease and normal aging is a unique 42-amino acid protein (amyloid beta-protein), suggesting a common origin for these pathological entities. However, the expression of the amyloid precursor protein mRNA (APP mRNA) from which the amyloid beta-protein is derived varies between specific neuronal populations. To determine the conditions under which neuronal synthesis of amyloid beta-protein might contribute to the formation of these structures, we have studied the temporal pattern of APP mRNA expression in developing fetal rabbit hippocampal neurons in vitro. Using in situ hybridization with a biotinylated riboprobe transcribed from a cDNA which includes the region encoding the amyloid beta-protein, we have observed a developmentally specific pattern of APP mRNA hybridization during neuronal maturation in vitro.

Models of environmentally induced neurological disease: epidemiology and etiology of amyotrophic lateral sclerosis and parkinsonism-dementia in the Western Pacific

Amyotrophic lateral sclerosis (ALS) on Guam previously attained incidence rates 50 to 100 times that of the continental United States and Europe and accounted for one in five deaths among Chamorros over age 25. A second neurological disorder in high incidence, parkinsonism-dementia (PD), and the early appearance in those populations of neurofibrillary tangles such as are seen in Alzheimer's disease and normal ageing have also been noted. Incidence and mortality rates of both diseases have declined dramatically during the past 30 years, and today, the risk of developing either disease among Guamanian Chamorros is only several times higher than in non-Guamanian populations. The decline is most likely a consequence of increased acculturation over the past three decades, with a concomitant decrease in isolation, changes in dietary habits and local water supplies, and much less dependence on locally grown foodstuffs. Similar declines are evident in the remaining two Pacific foci of high- incidence ALS, namely the Kii Peninsula focus in Japan and southern West New Guinea where western contact and introduction of new foodstuffs have occurred.The accumulating epidemiological, genetic and environmental evidence, as well as the development of new and promising experimental animal models, support the hypothesis that a basic metabolic defect, provoked by chronic nutritional deficiencies of calcium, lead to increased intestinal absorption of toxic metals and the co-deposition of calcium, aluminium and silicon in neurons of patients with ALS and PD. This elemental deposition is thought to result in aberrant microtubule assembly and/or abnormal post-translational modification of the amyloid precursor protein leading to widespread formation of neurofibrillary tangles, the hallmark pathological features in these disorders. The naturalistic paradigms of these foci in the Western Pacific have provided insights to understanding not only ALS and PD but other neurological disorders, such as classical ALS, Parkinson's disease, Alzheimer's disease and early neuronal ageing.

High prevalence of human T-lymphotropic virus type I infection in isolated populations of the Western Pacific region confirmed by Western immunoblot

High prevalences of antibodies against human T-lymphotropic virus type I (HTLV-I), as confirmed by Western immunoblot, were found in several remote indigenous populations of the Solomon Islands and Vanuatu and in some isolated populations of New Guinea that had no contact with Japanese or Africans and little contact with Caucasians prior to our bleedings. By contrast, zero or very low prevalences of HTLV-I infection were found in Guamanians and Carolinians, despite more than 30 years of intense contact with the Japanese. A total of 1,601 sera, collected between 1963 and 1981 from 21 population groups in the Western Pacific, was tested by enzyme-linked immunosorbent assay (ELISA) for IgG antibodies to HTLV-I. By ELISA, prevalences of antibodies against HTLV-I ranged from zero to 50%. Seropositivity could be confirmed in only 12.5% of 48 ELISA-positive sera selected for testing by Western immunoblot. However, the confirmed HTLV-I seroprevalences in some Melanesian populations were still as high as those found in HTLV-I-endemic regions, such as southwestern Japan and the Caribbean basin. HTLV-I prevalences were similar among males and females, and acquisition of antibodies increased with age. Our data indicate that infections with HTLV-I or a related retrovirus have been widespread in the southwestern Pacific for over 25 year in populations with minimal outside contact, while some populations which had extensive Japanese contact have no evidence of infection. Furthermore, based on the high frequency of indeterminate Western immunoblots, we conclude that in Melanesia this may represent either incomplete specific reactivity to HTLV-I or the existence of an antigenic variant of HTLV-I, distinct from prototype Japanese, American, and European HTLV-I strains.

Isolation of fetal mouse motor neurons on discontinuous Percoll density gradients

The spinal cords of fetal NIH:CR mice, gestational age Day 12 to 14, were dissected free of meninges and dorsal root ganglia, chemically dissociated, and layered onto discontinuous Percoll gradients at densities 1.040, 1.050, and 1.060 g/ml. After centrifugation (800 Xg for 15 min at 4 degrees C), three morphologically, biochemically, and immunohistologically distinct cell populations were collected from the gradient interfaces. The first interface, located at a density of 1.040 g/ml, was choline acetyltransferase enriched (0.86 +/- 0.08) compared to the second and third fractions (0.42 +/- 0.01 and 0 pmol acetylcholine synthesized/microgram protein, respectively). When simultaneously cultured with fetal mouse cardiac muscle on a gelatin-polylysine-laminin substrate in serum-free medium, these cells developed the characteristics of motor neurons.

Bone mass in Guamanian patients with amyotrophic lateral sclerosis and parkinsonism-dementia

Bone mass, as assessed by measurements of total subperiosteal diameter and medullary width of the second metacarpal bone on hand-wrist radiographs, was evaluated for 31 Guamanian patients (15 males, 16 females) with amyotrophic lateral sclerosis (ALS), 67 patients (39 males, 28 females) with parkinsonism-dementia (PD), and 66 (34 males, 32 females) nonaffected Guamanian controls. Comparisons between the two disease groups and between each disease group and the nonaffected controls were made taking into account the sex, age, and disability status of each participant. At all ages, ALS patients of both sexes had significantly lower percent cortical areas (PCA) than did nonaffected controls. The ALS males also had significantly lower PCA than PD males, although no significant differences were observed between female ALS and PD patients. The PD patients of either sex had a lower PCA when compared to controls, but the differences were not statistically significant. The observed differences in PCA were due solely to increased medullary width, suggesting that the diminished cortical bone thickness resulted from greater bone resorption rather than differential bone growth. Longitudinal studies support the cross-sectional findings of accelerated bone loss among ALS patients. It is not possible to determine from the present data whether the observed differences in PCA of the second metacarpal of the ALS patients are due to atrophy of the first interosseous muscle, to a generalized resorption process inherently associated with the development and progression of ALS, or to factors not accounted for by the present analysis.