Epidemiological studies on horses infected with nematodes of the family Trichonematidae (Witenberg, 1925)

Observations are reported on seasonal changes in the age structure of populations of nematodes of the family Trichonematidae recovered at regular intervals from the lumens of the large intestines of horses slaughtered in S.W. England. The results show that changes in the size of parasitic populations of Trichonema nassatum follow seasonal variations in the rate of infection, more individuals maturing during summer/autumn than during winter/spring because of proportional differences in the numbers of infective larvae ingested from the pasture. In contrast, larvae of T. longibursatum, T. catinatum and T. goldi ingested by grazing horses during summer accumulate in the gut wall rather than promptly returning to the lumen and developing to maturity. Their development is apparently inhibited until the following spring when 4th-stage larvae emerge en masse and quickly reach the adult stage. The relationship between fluctuations in the size of the adult populations of the 4 species studied and the characteristic seasonal variations in horse faecal egg counts is discussed.     

The relation of sex,age, smoking status,birth rank and parental ages to pseudocholinesterase activity and phenotypes in a sample of Australian Caucasian adults

Summary The frequencies of the pseudocholinesterase alleles E₁ ^u, E₁ ^a and E₁ ^f have been determined in a random sample of Australian residents. The frequency of E₁ ^a is the highest yet reported in a large caucasian sample. The considerable variation in E₁ ^f frequencies in previously reported samples is discussed in terms of possible sources of error in fluoride number determinations.Enzyme activity was found to increase with age in adulthood and was higher in males than in females. It was also positively correlated with dibucaine number in type U subjects. These observations are in conflict with those reported in previous investigations.This work was supported by grants from the National Health and Medical Research Council of Australia and the Australian Tobacco Research Foundation.     

Disseminated cutaneous and vascular invasion byFusarium moniliforme in a fatal case of acute lymphocytic leukemia

A 35 year old female patient with acute lymphocytic leukemia developed fusariosis in which dissemination appeared to be limited to cutaneous and vascular invasion. The first evidence of fungemia occurred nearly seven months after initial hospitalization. The fungus was identified asFusarium sp. and was considered a contaminant. Two weeks later blood cultures were again positive forFusarium sp. and the patient was placed on amphotericin B and 5-fluorocytosine therapy. The following day developing lesions were noted on her forearms and face; lesions ultimately spread to her trunk, abdomen, and lower extremities. Skin lesion biopsy sections revealed abundant septate and branching hyphae throughout the dermis and within capillaries. Twenty-six days after the initial isolation the patient died. Post-mortem blood cultures gave rise to the same fungus, which was identified asFusarium monoliforme. Postmortem cultures and stains of spleen, liver, lung, and brain specimens were all negative for fungi. The primary source and portal of entry of the organism remained undetermined.     

Genetic Analysis of Voltage-Dependent Calcium Channels

Molecular cloning of calcium channel subunit genes has identified an unexpectedly large number of genes and splicing variants, and a central problem of calcium channel biology is to now understand the functional significance of this genetic complexity. While electrophyisological, pharmacological, and molecular cloning techniques are providing one level of understanding, a complete understanding will require many additional kinds of studies, including genetic studies done in intact animals. In this regard, an intriguing variety of episodic diseases have recently been identified that result from defects in calcium channel genes. A study of these diseases illustrates the kind of insights into calcium channel function that can be expected from this method of inquiry.     

SOME PROPERTIES OF DNA FROM ZOOXANTHELLAE HARBORED BY AN ANEMONE ANTHOPLEURA ELEGANTISSIMA1

Native DNA from the zooxanthellae harbored by an anemone, Anthopleura elegantissima consists of 2 species resolvable by differences in bouyant density in CsCl. Nuclear DNA has a density of 1.695 g/ml. Chloroplast DNA bands at a density of 1.688 g/ml. A third species of DNA, also with a density of 1.695 g/ml in the native state, is presumably mitochondrial DNA. It was detected in heat-denatured preparations. Nuclear DNA contains, in addition to the 4 usual bases, some 5-methyl cytosine. The latter was absent from chloroplast fractions.     

The ligase chain reaction distinguishes hepatitis B virus S-gene variants

Abstract The functional significance of charged amino acids of the anion-selective porin Omp34 from Acidovorax delafieldii was investigated by means of conductance measurements. Chemical modification of Lys and Arg as well as titration of charges by adjusting the pH value revealed that positively charged amino acid residues determine the major functional properties of the porin. Positive charges are involved in creating the protein surface potential, the selectivity filter inside the channels, and the voltage-sensing and/or gating mechanisms.     

Acute and chronic effects of an aromatase inhibitor on territorial aggression in breeding and nonbreeding male song sparrows

Many studies have demonstrated that male aggression is regulated by testosterone. The conversion of testosterone to estradiol by brain aromatase is also known to regulate male aggression in the breeding season. Male song sparrows (Melospiza melodia morphna) are territorial not only in the breeding season, but also in the nonbreeding season, when plasma testosterone and estradiol levels are basal. Castration has no effect on nonbreeding aggression. In contrast, chronic (10 day) aromatase inhibitor (fadrozole) treatment decreases nonbreeding aggression, indicating a role for estrogens. Here, we show that acute (1 day) fadrozole treatment decreases nonbreeding territoriality, suggesting relatively rapid estrogen effects. In spring, fadrozole decreases brain aromatase activity, but acute and chronic fadrozole treatments do not significantly decrease aggression, although trends for some behaviors approach significance. In gonadally intact birds, fadrozole may be less effective at reducing aggression in the spring. This might occur because fadrozole causes a large increase in plasma testosterone in intact breeding males. Alternatively, estradiol may be more important for territoriality in winter than spring. We hypothesize that sex steroids regulate male aggression in spring and winter, but the endocrine mechanisms vary seasonally.