Amino acid uptake required for long-term memory formation

α-Amino-iso-butyrate (AIB) inhibits long-term, protein synthesis-dependent memory formation by reducing labelled leucine uptake in vivo without affecting leucine incorporation into protein. Unlike the antibiotic cycloheximide, AIB does not block long-term memory formation through inhibition of protein synthesis per se. The behavioural effect of AIB is restricted to times of administration between 5 min before and 5 min after learning a single trial passive avoidance task by day-old chickens. It is concluded that (1) AIB competes with normal amino acids for uptake into cells, and (2) the uptake of amino acids for protein synthesis specific to long-term memory formation takes place in the first few minutes following learning.     

Ceratobium mosaic potyvirus: another virus from orchids

Summary.  A potyvirus, which we call ceratobium mosaic virus, has been detected in about one third of more than 100 plants representing c. 33 orchid genera in two collections in Australia. It was detected using RT-PCR with redundant primers that are Potyviridae-specific and have additional sequences corresponding to either the SP6 or T7 bacteriophage promoters at their 5′-termini. Thus the nucleotide sequence of the resulting PCR fragments, consisting of about 1.7 kb of the 3′ portion of the viral genome, could be determined directly. Viral sequences obtained from five infected orchids indicate that they contained different isolates of a single potyvirus species most closely related to the bean common mosaic group of potyviruses, but clearly distinct from all whose virion protein genes have been reported to the international gene sequence databases. Accepted December 18, 1997 Received September 9, 1997     

Differences in susceptibility of inbred mice to Bacillus anthracis.

Animal species differ in their resistance both to infection by Bacillus anthracis and to anthrax toxin. A mouse model was developed to study the basis of the host differences and the pathogenesis of infection. When mice were infected with the virulent B. anthracis strain Vollum 1B, low 50% lethal dose (LD50) values (5 to 30 spores) were found for all 10 strains of inbred mice tested. However, analysis of time-to-death data revealed significant differences among the strains, which could be divided into three groups: most susceptible (A/J and DBA/2J); least susceptible (CBA/J, BALB/cJ, and C57BR/cdJ); and intermediate (the remaining five strains). In contrast, the mice were distinctly susceptible or resistant to lethal infection by the toxigenic, nonencapsulated Sterne vaccine strain. The LD50 for the susceptible A/J and DBA/2J mice was approximately 10(3) spores of the Sterne strain, whereas the remaining eight relatively resistant strains were killed only by 10(6) or more spores. F1 hybrid and backcross studies suggested that resistance to the Sterne strain is determined by a single dominant gene or gene complex. Mice lethally infected with B. anthracis showed an acute course of infection, characterized by extensive gelatinous edema and large concentrations of bacilli in the blood and organs (e.g., 10(9) CFU/g of spleen). The susceptibility of A/J and CBA/J mice to intravenously injected anthrax toxin components appeared to differ from their susceptibility to infection. The toxin LD50 values for both strains were similar. However, CBA/J mice died sooner than did A/J mice, with mean time to death of 0.9 and 3.7 days, respectively, in mice given 4 LD50 of toxin. The mouse model appears to be useful in studies on host resistance to anthrax and on the pathogenesis of the infection.     

A monoclonal blocking EIA for herpes simplex virus type 2 antibody: validation for seroepidemiological studies in Africa

A competitive type-specific enzyme-linked immunosorbent assay (ELISA) for herpes simplex virus type 2 (HSV-2) antibody was developed using an infected cell antigen and a monoclonal antibody to glycoprotein G-2. This assay has been validated for use for epidemiological studies using a large panel of sera collected in rural Uganda and a panel of 143 sera characterised previously by Western blotting, the 'gold standard' for HSV type-specific serology. This evaluation was found to have a sensitivity of 96% and a specificity of 91% in comparison with Western blot on 143 sera from clinic patients. The ELISA had a sensitivity of 93% and a specificity of 91% in comparison with Western blot on 495 sera collected in Uganda. The assay showed good reproducibility and a low percentage of sera gave equivocal results, indicating its suitability for epidemiological studies.     

Acute energetic effects of daunomycin on rabbit heart muscle

The acute effects of daunomycin on the mechanical and energetic outputs of rabbit papillary muscles have been examined at 27 degrees C using a myothermic technique. Contrary to expectations, daunomycin, in concentrations ranging from 10 to 160 micrograms/ml, acted as a positive inotropic agent in terms of peak stress development and work output. The rate of stress development was, however, slightly depressed, and the major mechanical effect of the drug was to prolong the relaxation phase so that there were large drug-dependent increments in the stress-time integral. Daunomycin at a concentration of 80 micrograms/ml produced a 22% increment in peak stress development and a 74% increment in stress-time integral. The linear relationship between total (active + passive) stress and heat production was altered such that there was a 73% increment in the activation heat component (intercept) and a 37% increase in the energy cost per unit stress development (slope). In afterloaded isotonic contractions, daunomycin increased the mean work output (W; averaged over all load levels) by 49%, but there was an even greater increment in the associated energy expenditure, ET, which rose by 66%. Consequently, the overall mechanical efficiency (W/ET X 100%) fell slightly. It is concluded that, in the rabbit, daunomycin in the acute situation increases total calcium delivery to the myofilaments and decreases the "apparent" transduction efficiency. These acute effects are the opposite of those reported in papillary muscles taken from rabbits in cardiac failure induced by chronic daunomycin administration. The short-term effects of daunomycin in the rabbit differ substantially from those seen in the rat and guinea pig.     

Magnetic resonance imaging of femoral head development in roentgenographically normal patients

Magnetic resonance images (MRI) of 22 patients with roentgenographically normal hips were reviewed retrospectively and the findings categorized according to age. With increasing maturity, the MR intensity of the femoral heads on spin echo images increased, as marrow fat became a dominant tissue in the head. The femoral head pattern was relatively inhomogeneous, with a broad band of diminished intensity extending in a posteromedial to anterolateral direction, corresponding to the pattern of trabecular bone. The femoral capital epiphyses were visible in younger patients as structures of bright intensity which remained evident through early adulthood. The articular cartilage of the hip joint was noted as a distinctive halo around the femoral head. An understanding of the MR pattern of the normal hip will aid in the early recognition of pathologic conditions, such as osteonecrosis.     

Monoclonal antibody analysis of keratin expression in the central nervous system

A monoclonal antibody directed against a 65-kDa brain protein demonstrates an epitope found in keratin from human epidermis. By indirect immunofluorescence, the antibody decorates intracytoplasmic filaments in a subclass of astrocytes and Purkinje cells of adult hamster brain. Double-label immunofluorescence study using antibody to glial fibrillary acidic protein and this antibody reveals the 65-kDa protein to be closely associated with glial filaments in astrocytes of fetal mouse brain cultures. Immunoblot analysis of purified human epidermal keratin and hamster brain homogenate confirms the reactivity of this antibody to epidermal keratin polypeptides. All the major epidermal keratins were recognized by this antibody. It did not bind to the remaining major intermediate filament proteins. These findings suggest that monoclonal antibody 34C9 recognizes a cytoskeletal structure connected with intermediate filaments. In addition, the monoclonal antibody demonstrates that epidermal keratins share an epitope not only among themselves but also with a "neural keratin."     

Variation in General Practice Services Provided to Australian Workers with Low Back Pain: A Cross-Jurisdictional Comparative Study

Journal of Occupational Rehabilitation - Purpose: To compare the frequency of General Practitioner (GP) services and the time between first and last GP services (service duration) provided to...     

Exploring Differences in Work Disability Duration by Size of Firm in Canada and Australia

Journal of Occupational Rehabilitation - Purpose To identify whether there were differences in work disability duration between injured workers employed by small, medium, large, and self-insured...     

Assessing the Impact of Salt Reduction Initiatives on the Chronic Disease Burden of Singapore

Globally, many countries are facing an increasing burden of chronic disease due to ageing populations, of which cardiovascular disease forms a large proportion. Excess dietary sodium contributes to cardiovascular disease risk and requires intervention at a population level. This study aimed to quantify the impact of several salt reduction initiatives on population health over a 30-year horizon using GeoDEMOS, a population model from Singapore. Four interventions were modelled in four demographic groups in 2020 for a total of 16 intervention scenarios. The effect of 0.5, 2.0, and 4.0 g/day reductions in daily salt consumption, along with adherence to the World Health Organization guidelines of a maximum of 5.0 g of salt each day, was modelled in the entire population, including the overweight and obese, the elderly, and diabetics. In each scenario, the number of averted incident cases of acute myocardial infarction and stroke, along with the disability-adjusted life years up to 2050, was monitored. We found 4.0 g/day reductions in salt consumption were the most effective when implemented across the entire population, resulting in 24,000 averted incident cases of cardiovascular disease and 215,000 disability-adjusted life years over 30 years. This is a large figure when compared with the 29,200 projected annual incident cases of cardiovascular disease in 2050. When targeted at specific high-risk demographic groups, the largest effects were observed in the overweight and obese, with the same intervention yielding 10,500 averted incident cases of cardiovascular disease and 91,500 disability-adjusted life years. Quantifying the benefits of salt reduction initiatives revealed a significant impact when administered across the entire population or the overweight and obese. Health promotion efforts directed toward sustainably reducing salt consumption will help to lower the chronic disease burden on the healthcare system in years to come.