Does ageing have an effect on midbrain premotor nuclei for vertical eye movements?

Currently, there is debate in the clinical literature as to whether defects in vertical gaze are a consequence of normal ageing or a component of an underlying neurodegenerative disorder. Although pathological changes have been demonstrated in diseased subjects, no study to date has addressed the question of normal ageing effects. In this retrospective study, we examined 23 neurologically and pathologically normal subjects (age 18-91). Using an unbiased, frame-based sampling method, we quantified neuronal and glial cell densities in 10 young (<50) and 13 aged (>65) subjects in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), the key premotor substrate in the vertical gaze pathway. We found no statistically significant difference in neuronal density, glial cell density, or neuron-to-glial cell ratios between the young and the aged. We conclude, therefore, that neuronal loss, neuronal atrophy, or gliosis in the riMLF are not consequences of normal ageing.     

Pelizaeus-Merzbacher disease: classical or connatal?

The clinical features and investigation results of 7 patients with Pelizaeus-Merzbacher disease (PMD) are described; one patient had a brain biopsy and two patients had an autopsy. This paper tries to differentiate the clinical features of the connatal and classical types of PMD. Transient stridor and nystagmus were early signs in both types of PMD. Our findings support the view that the more severe connatal form shows rapid neurological deterioration from an early age leading to death usually in the first decade. In younger patients in whom the evolution is still unclear, severe feeding problems and extrapyramidal features may suggest the connatal form. By contrast, in the classical form of PMD, cerebellar signs and cognitive deterioration are more prominent with a more slowly progressive course. Nuclear magnetic resonance imaging and brainstem auditory evoked potentials were very helpful in supporting the diagnosis of PMD either in a known affected family or in sporadic cases, but were not useful in distinguishing between the two types of PMD. Genetic counseling in this condition is difficult, particularly in the connatal form in which inheritance may be either X-linked or autosomal recessive.     

Interaction of Nucleoside Analogues with the Sodium–Nucleoside Transport System in Brush Border Membrane Vesicles from Human Kidney

The therapeutic efficacy of nucleosides and nucleoside analogues as antitumor, antiviral, antiparasitic, and antiarrhythmic agents has been well documented. Pharmacokinetic studies suggest that many of these compounds are actively transported in the kidney. The goal of this study was to determine if therapeutically relevant nucleosides or analogues interact with the recently characterized Na⁺-driven nucleoside transport system of the brush border membrane of the human kidney. Brush border membrane vesicles (BBMV) were prepared from human kidney by divalent cation precipitation and differential centrifugation. The initial Na⁺-driven ³H-uridine uptake into vesicles was determined by rapid filtration. The effect of several naturally occurring nucleosides (cytidine, thymidine, adenosine), a pyrimidine base (uracil), a nucleotide (UMP), and several synthetic nucleoside analogues [zidovudine (AZT), cytarabine (Ara-C), and dideoxycytidine (ddC)] on Na⁺–uridine transport was determined. At a concentration of 100 µM the naturally occurring nucleosides, uracil, and UMP significantly inhibited Na+-uridine transport, whereas the three synthetic nucleoside analogues did not. Adenosine competitively inhibited Na+-uridine uptake with a K _i of 26.4 µM (determined by constructing a Dixon plot). These data suggest that naturally occurring nucleosides are substrates of the Na⁺–nucleoside transport system in the renal brush border membrane, whereas synthetic nucleoside analogues with modifications on the ribose ring are not. The K _i of adenosine is higher than clinically observed concentrations and suggests that the system may play a physiologic role in the disposition of this nucleoside.     

Autosomal recessive microcephaly, mental retardation with nonpigmentary retinopathy and a distinctive electroretinogram

The association of microcephaly and mental retardation with a non-pigmentary retinopathy is described in three siblings of consanguineous parents. The electroretinogram showed the distinctive appearance of markedly attenuated "b" wave but normal "a" wave suggestive of a retinal dystrophy primarily affecting post-receptoral elements in the inner retina. This appears to be an autosomal recessive condition which has not been previously reported.     

Mechanical Analysis of Atherosclerotic Plaques Based on Optical Coherence Tomography

Finite element analysis is a powerful tool for investigating the biomechanics of atherosclerosis and has thereby provided an improved understanding of acute myocardial infarction. Structural analysis of arterial walls is traditionally performed using geometry contours derived from histology. In this paper we demonstrate the first use of a new imaging technique, optical coherence tomography (OCT), as a basis for finite element analysis. There are two primary benefits of OCT relative to histology: 1) imaging is performed without excessive tissue handling, providing a more realistic geometry than histology and avoiding structural artifacts common to histologic processing, and 2) OCT imaging can be performed in vivo, making it possible to study disease progression and the effect of therapeutic treatments in animal models and living patients. Patterns of mechanical stress and strain distributions computed from finite element analysis based on OCT were compared with those from modeling based on "gold standard" histology. Our results indicate that vascular structure and composition determined by OCT provides an adequate basis for investigating the biomechanical factors relevant to atherosclerosis and acute myocardial infarction.     

Transformation of the oomycete pathogen Phytophthora megasperma f. sp. glycinea occurs by DNA integration into single or multiple chromosomes

A procedure for stable transformation was developed for Phytophthora megasperma f. sp. glycinea, an oomycete pathogen of soybean. Transformants were obtained using a bacterial hygromycin resistance gene fused to a promoter and terminator from the ham34 gene of another oomycete, Bremia lactucae. Vector DNA, alone or complexed to cationic liposomes, was introduced into protoplasts using polyethylene glycol and CaCl₂. DNA and RNA hybridization, and phosphotransferase assays, confirmed the presence and expression of vector DNA in the transformants. Hybridization to electrophoretically separated chromosomes of P. m. glycinea showed that vector DNA had integrated into only one chromosome in four transformants, and into multiple chromosomes in one transformant.     

Survey of the Distribution of a Newly Characterized Receptor for Advanced Glycation End Products in Tissues

Advanced glycation end products (AGEs), the final products of nonenzymatic glycation and oxidation of proteins, are found in the plasma and accumulate in the tissues during aging and at an accelerated rate in diabetes. A novel integral membrane protein, termed receptor for AGE (RAGE), forms a central part of the cell surface binding site for AGEs. Using monospecific, polyclonal antibody raised to human recombinant and bovine RAGE, immunostaining of bovine tissues showed RAGE in the vasculature, endothelium, and smooth muscle cells and in mononuclear cells in the tissues. Consistent with these data, RAGE antigen and mRNA were identified in cultured bovine endothelium, vascular smooth muscle, and monocyte-derived macrophages. RAGE antigen was also visualized in bovine cardiac myocytes as well as in cultures of neonatal rat cardiac myocytes and in neural tissue where motor neurons, peripheral nerves, and a population of cortical neurons were positive. In situ hybridization confirmed the presence of RAGE mRNA in the tissues, and studies with rat PC12 pheochromocytes indicated that they provide a neuronal-related cell culture model for examining RAGE expression. Pathological studies of human atherosclerotic plaques showed infiltration of RAGE-expressing cells in the expanded intima. These results indicate that RAGE is present in multiple tissues and suggest the potential relevance of AGE-RAGE interactions for modulating properties of the vasculature as well as neural and cardiac function, prominent areas of involvement in diabetes and in the normal aging process.     

Evaluation of screened blood donations for human immunodeficiency virus type 1 infection by culture and DNA amplification of pooled cells

BACKGROUND. Reports of transmission of the human immunodeficiency virus type 1 (HIV-1) from transfusions of screened blood and reports of silent, antibody-negative HIV-1 infections in persons at high risk continue to foster concern about the safety of the blood supply. Previous estimates of the risk of HIV-1 range from 1 in 38,000 to 1 in 300,000 per unit of blood but are based on either epidemiologic models or the demonstration of seroconversion in recipients. METHODS. We isolated peripheral-blood mononuclear cells from blood that was fully screened and found to be seronegative, combined them into pools of cells from 50 donors, and tested them for HIV-1 by viral culture and the polymerase chain reaction, using protocols specifically adapted for this analysis. RESULTS. The 1530 pools of mononuclear cells were prepared from 76,500 blood donations made in San Francisco between November 1987 and December 1989. Of these pools, 1436 (representing 71,800 donations) were cultured successfully; 873 (43,650 donations) were evaluated by the polymerase chain reaction. Only one pool was confirmed as HIV-1--infected by both methods. After adjustment for sample-based estimates of the sensitivity of the detection systems using culture and the polymerase chain reaction, the probability that a screened donor will be positive for HIV-1 was estimated as 1 in 61,171 (95 percent upper confidence bound, 1 in 10,695). CONCLUSIONS. Silent HIV-1 infections are exceedingly rare among screened blood donors, so the current risk of HIV-1 transmission from blood transfusions, even in high-prevalence metropolitan areas, is extremely low.     

Limiting dilution analysis of the human T cell response to mycobacterial antigens from BCG vaccinated individuals and leprosy patients.

The number of peripheral blood T lymphocytes responding to soluble mycobacterial antigens from Mycobacterium tuberculosis purified protein derivative (PPD) and M. leprae (MLS) was estimated by limiting dilution analysis. Antigen-induced lymphocyte activation was measured by means of [3H]TdR incorporation on day 10 of culture in the presence of suboptimal concentrations of interleukin 2 (IL-2). In the peripheral blood of BCG-vaccinated individuals from the UK, the frequency of T lymphocytes responding to PPD was 1.5 to 4 times greater than to MLS. Frequencies between 1/1970 and 1/13, 982 were observed in response to PPD and between 1/4097 and 1/24, 717 in response to MLS. A proportion of cells in the peripheral blood were also observed to respond to IL-2 only. The frequency of cells observed in limiting dilution analysis for PPD and MLS reflected the relative amounts of proliferation to these two antigens in bulk culture lymphocyte transformation tests. Use of PPD-specific T cell lines suggested that the responsiveness observed to M. leprae antigens in BCG-vaccinated individuals was due to cross-reactivity with antigens shared with M. bovis BCG. In tuberculoid leprosy, the frequency of peripheral blood T lymphocytes responding to M. leprae antigens was either greater than or similar to the frequency of T cells responding to PPD. In contrast, limiting dilution analysis of T lymphocytes from the peripheral blood of lepromatous leprosy patients revealed the complex regulatory heterogeneity of this group. In some patients M. leprae responsive T cells were detected in the presence of exogenous IL-2.