Estimates of the effects of folic-acid fortification and folic-acid bioavailability for women.

OBJECTIVE: With the recent implementation of the folic-acid-fortification program, our objective was to estimate its benefits in adult women and account for the higher bioavailability of synthetic folic acid in fortification programs and supplements. METHODS: The study used a cross-sectional design. Dietary assessment data were collected with a quantitative food-frequency questionnaire, the Nutrition DISCovery program. Fortification was simulated with the use of fortification standards (140 microg/100 g of flour) and new bioavailability standards for synthetic folic acid. Data were collected from 289 women 18 to 89 y old. Subjects were recruited from participants in two health-screening events in autumn of 1997. Chi-square tests were used to estimate the differences between categoric variables, and F tests were used in analysis of variance for continuous outcome measures. Results were considered significant at P < 0.05. RESULTS: Estimated mean dietary intake of folate increased considerably with simulation of fortification (320 to 608 microg of dietary folate equivalents). Women in the lower quartiles for age (18 to 39 and 40 to 46 y) consumed more servings from the bread group than women did in the upper quartile (55 to 89 y). Thus, the improvement in folate intake with fortification was significantly greater for the younger than for the older women (P < 0.05). Despite the limitations of estimating folate intakes, these data suggest that most women met the new estimated average requirement. However, 61% of women of childbearing age had intakes of synthetic folic acid below the recommended level of 400 microg/d, and only those using supplements containing folic acid met the guideline. CONCLUSIONS: Based on this sample of well-educated, adult women, the current level of folic-acid fortification should improve the intakes of a large proportion of women, especially when accompanied by supplements containing folic acid. These improvements in folate intake might not be seen in groups with limited resources, however. Further, under existing standards and practices, many women will not meet current recommendations for prevention of neural-tube defects.

The infectivity of Encephalitozoon cuniculi in vivo and in vitro.

The infectivity of Encephalitozoon cuniculi grown in cell cultures was determined in cultured cells and in wild and domestic rabbits. The ratio of the total to tissue culture viable count was 1,300 (median of seven determinations). The mean ratio of intact spore count to total count, as determined by electron microscopy was 0.12. Although variation between infectivity experiments was large, the median animal infective dose contained 51 FFU (cell culture focus-forming units) for wild rabbits (Oryctolagus cuniculus) and 40 FFU for domestic rabbits. These two infectivities were not statistically different.

Toxoplasmosis and the wild rabbit Oryctolagus cuniculus in Victoria, Australia with suggested mechanisms for dissemination of oocysts.

Sera or serum eluates from 1697 wild rabbits [Oryctolagus cuniculus (L)], collected over the past 10 years from 24 sites in 5 geographic regions of Victoria, were examined for antibodies to Toxoplasma gondii. Sera generally were classified into three broad groups, negative (titre less than 10), weakly reactive (titre 10 to 100) and strongly positive (titre greater than 1000). Strongly positive sera came from rabbits collected in a small number of localized areas, most significantly the Melbourne and Metropolitan Board of Works (MMBW) Sewerage Farm at Werribee and Mud Island in Port Phillip Bay.

Lack of serological evidence for venereal spirochaetosis in wild Victorian rabbits and the susceptibility of laboratory rabbits to Treponema paraluis-cuniculi.

Sera from 608 wild rabbits were examined using serological tests for syphilis as an indicator of infection with Treponema paraluis-cuniculi. Only eight sera gave positive or weakly positive results in the rapid plasma reagin (RPR) test, and none of these eight sera gave positive results in the Treponema pallidum haemagglutination assay (TPHA). Thus, it appears that wild rabbit populations in Victoria, Australia, are not naturally infected with T paraluis-cuniculi. Normal Australian laboratory rabbits however were readily infected with T paraluis-cuniculi, either by intradermal or intratesticular inoculation or by the venereal route. In the latter case, treponeme-containing lesions developed after about five months' cohabitation with infected mates. The disease was successfully transmitted from male to female and from female to male rabbits by the venereal route. In most cases infected rabbits became RPR-positive (17/19 rabbits) and in all cases TPHA-positive (19/19), indicating that serological tests for syphilis can be used to screen rabbits for this disease.

An investigation of Encephalitozoon cuniculi in the wild rabbit Oryctolagus cuniculus in Victoria, Australia.

Sera from 823 wild rabbits (Oryctolagus cuniculus) collected from a number of geographic regions of Victoria, Australia over the past eight years were examined for antibodies to Encephalitozoon cuniculi, along with sera from 46 hares (Lepus europaeus) (Pallas) and 57 New Zealand wild rabbits. No sera were positive, implying that this common laboratory rabbit parasite is absent from wild rabbits in these areas. However, wild rabbits were found to be readily infected by the oral route with small numbers of tissue-culture-grown spores of E. cuniculi. A possible explanation for the absence of encephalitozoonosis in wild rabbits is that E. cuniculi infection places them at a biological disadvantage for survival. The natural hygiene habit of wild rabbits may also significantly decrease post-natal infection.

Myxomatosis: the emergence of male and female European rabbit fleas Spilopsyllus cuniculi (Dale) from laboratory cultures.

The sex ratios and the emergence patterns of the European rabbit flea bred under animal house conditions were examined. An overall preponderance of female fleas was found. This was due to the greater preponderance of female fleas in the primary emergence, whereas the sex ratios in the secondary emergence were about 1:1.

Myxomatosis: the release and spread of the European rabbit flea Spilopsyllus cuniculi (Dale) in the Central District of Victoria.

The European rabbit flea was first released in Victoria in August 1969 at Werribee. Releases were made on five different land forms. At one site the first flea was recovered 2 weeks after release. Fleas were recovered between 4 and 6 weeks after release at the other sites. Differences in establishment and spread on the different land forms were due to physically restricted movement of some rabbit populations. By June 1971 80% of rabbits were infested but an occasional young uninfested rabbit was still found in August 1978. Infestation numbers were higher than in the Mallee region especially on pregnant does.

Myxomatosis: changes in the epidemiology of myxomatosis coincident with the establishment of the European rabbit flea Spilopsyllus cuniculi (Dale) in the Mallee region of Victoria.

Outbreaks of myxomatosis during the winter or spring have coincided with the establishment of the European rabbit flea in the Mallee region. The severity of these outbreaks has varied from causing complete suppression of the normal spring increase in rabbit numbers to being completely ineffective in a year in which late spring rains allowed rabbit breeding to extend into the early summer.In 1973 and 1974 effective spring myxomatosis caused heavy mortality in kittens before they emerged from the warrens. The age of the population increased as the result of few young rabbits coming into the population and of the lessened stress on old rabbits in a low summer-autumn population. This effect was reversed in the late-breeding year, 1976, when flea numbers were apparently too low to maintain a spring outbreak and rabbit numbers increased rapidly.

Myxomatosis in the Mallee region of Victoria, Australia.

Sharp reductions in the wild rabbit (Oryctolagus cuniculus (L.)) population in the Mallee are associated with annual myxomatosis epizootics. The extent to which the population reductions are the direct result of the epizootics varies with time of epizootic occurrence. All grazing animals in the Mallee are under nutritional stress each summer and autumn. When the epizootic occurs during the early summer heavy losses occur in a previously healthy population. Similar losses which occur in the late summer and autumn are the result of a nutritional stress - epizootic complex. The end result in each case is a population reduction of about 80%. This reduction occurs in a population which is the most resistant to myxomatosis known in Victoria and in association with epizootics caused by field strains of myxoma virus of moderate virulence only. The earlier summer epizootics are of considerable economic importance because they sharply reduce the pressure on the limited food available for other grazing animals.

Myxomatosis: the occurrence of antibody to a soluble antigen of myxoma virus in wild rabbits, Oryctolagus cuniculus (L.), in Victoria, Australia.

The occurrence of antibody of myxoma virus in wild rabbits following epizootics is highest in the semi-arid north-west of Victoria and lowest in temperate southern Victoria. Occurrence ranges up to about 90% in the north-west and to about 70% in the south except on the Western Plains where epizootics are rare and antibody occurrence seldom exceeds 30%. The establishment of the European rabbit flea may be changing the pattern of occurrence of antibody in the north-west by causing spring outbreaks of myxomatosis. It is suggested that the effects of the replacement of a simple recurring system of epizootic and breeding season several months apart by the occurrence of myxomatosis twice in the same year, once coincident with the breeding season, will be complex. The occurrence of detectable antibody may be less dependent on the infection rate and may be dependent to some extent on the relative timing of spring myxomatosis and the breeding season.

Myxomatosis: the transmission of a highly virulent strain of myxoma virus by the European rabbit flea Sphilopsyllus cuniculi (Dale) in the Mallee region of Victoria.

The European rabbit flea Spilopsyllus cuniculi (Daley was introduced into Australia to act as a vector of myxoma virus. It was first released in the semi-arid Mallee region of Victoria in 1970 where epizootics cuased by field strains of myxoma virus occur each summer. Introductions of the readily identified Lausanne strain were made annually following the release of the flea. The introductions were successful and the strain persisted for up to 16 weeks despite competition from field strains. The Lausanne strain is more readily spread by fleas than the Glenfield strain which has been widely used in rabbit control. The ability of the Lausanne strain to persist and its effective transmission compared with the Glenfield strain may be due in part to the more florid symptoms of the disease.

Myxomatosis on the Western Plains of Victoria.

Myxomatosis on the Western Plains is an enzootic disease in contrast with the epizootic pattern which is general in eastern Australia. The most unusual aspects are the presence of significant numbers of diseased rabbits throughout the winter and the continuously low percentage of rabbits with antibodies to myxoma virus. Climatic and topographic conditions are unsuited to the production of the high densities of mosquitoes necessary for widespread epizootics. Under these conditions the effects of less efficient methods of myxomatosis transmission are apparent. The unusual epidemiology of myxomatosis has resulted in selection for virulence of the virus similar to that which has occurred under summer epizootic conditions. All field strains are now in the mid range of virulence.

Population genetics of Aa and Ab immunoglobulin allotypes in wild rabbits of south-eastern Australia. I. Allotype frequencies.

Aa and Ab allotype frequencies have been investigated in wild rabbit populations throughout Victoria and South-east South Australia. The overall mean allele frequencies for thirty-three populations are 0-53:0-12:0-36 for a1:a2:a3 and 0-72:0-22:0-05 for b4:b5:b9. The b6 allele was not found anywhere. The a1 frequency has been found to increase in proportion to increases in mean annual rainfall. While considerable variations exist in allotype and allele frequencies from area to area, the relationships a1 greater than a3 greater than a2 and b4 greater than b5 greater than b9 are almost always observed. The results are discussed in terms of the historical origins of Australian wild rabbits and possible genetic mechanisms to explain the maintenance of allotype 'hierarchies' in large populations breeding at random.

Myxomatosis: the virulence of field strains of myxoma virus in a population of wild rabbits (Oryctolagus cuniculus L.) with high resistance to myxomatosis.

The virulence of field strains of myxoma virus is increasing in the Mallee region of Victoria where the resistance of the rabbit to myxomatosis is high. This suggests that the climax association will be a moderately severe disease.

Molecular conformation prostaglandin A1 monoclinic crystalline polymorph.

The molecular conformation of the monoclinic crystalline polymorph of prostaglandin A1 has been determined by X-ray diffraction techniques. The space group is P21 with a = 13.637(2), b = 7.567(1), c = 10.576(2) A, beta = 107.37(3) degrees; Dc = 1.073 g.cm-3 for Z = 2. The molecular conformation is characterized by the nearly parallel arrangement of the C1-C7 and C13-C20 side chains, with a general flattening of the overall structure when compared with the orthorhombic polymorph. The cyclopentenone moiety assumes a C8 envelope conformation with C8 and O9 displaced +0.29 A and -0.18 A from the C9-C10=C11-C12 plane respectively. Concerted, small varations of the torsion angles, primarily about the C8-C12, C14-C15 and C16-C17 bonds, bring the monoclinic and orthorhombic conformations into coincidence.