The Use of Wheat Crops by Grey Kangaroos, Macropus-Giganteus, in Southern Queensland

Aerial surveys of eastern grey kangaroos, Macropus giganteus, were conducted over the western edge of the wheat belt of southern Queensland in two wet years (1983 and 1984) and one year of average rainfall (1985). Because most kangaroos moved rapidly off crops shortly after dawn and returned shortly before dusk, flights within 15 min of dawn and dusk provided the best indicators of kangaroo crop usage. Very low densities were observed on mature crops in all years and on immature crops in the two wetter years. In July 1985, which was drier, a density of 11 kangaroos km-2 was recorded on immature crops. This density was comparable with that for all uncultivated land in the surveyed area. Close to undeveloped land, densities of 14-17 kangaroos km-2 were observed on crops.

A latex agglutination assay for D dimer: evaluation and application to the diagnosis of thrombotic disease

Although latex agglutination assays have been used for some years to diagnose thrombotic disorders, only recently has it been possible to measure specifically the products of fibrin breakdown in the presence of fibrinogen degradation products, by using monoclonal antibodies. We have evaluated a preparation of latex particles coupled to the monoclonal antibody DD-3B6/22, which is specific for cross-linked fibrin degradation products (XDP) and allows accurate discrimination between normal and pathological conditions. Of samples from 515 apparently healthy volunteers, 97.7% failed to agglutinate the latex; the normal reference interval for XDP determined by enzyme immunoassay was less than 78-320 micrograms/L. The use of different anticoagulants with or without the addition of a protease inhibitor had no significant effects on the results of the latex assay. The latex preparation provides a useful, rapid diagnostic tool for assaying small numbers of samples or as an emergency test.

A latex agglutination assay for D dimer: evaluation and application to the diagnosis of thrombotic disease

Although latex agglutination assays have been used for some years to diagnose thrombotic disorders, only recently has it been possible to measure specifically the products of fibrin breakdown in the presence of fibrinogen degradation products, by using monoclonal antibodies. We have evaluated a preparation of latex particles coupled to the monoclonal antibody DD-3B6/22, which is specific for cross-linked fibrin degradation products (XDP) and allows accurate discrimination between normal and pathological conditions. Of samples from 515 apparently healthy volunteers, 97.7% failed to agglutinate the latex; the normal reference interval for XDP determined by enzyme immunoassay was less than 78-320 micrograms/L. The use of different anticoagulants with or without the addition of a protease inhibitor had no significant effects on the results of the latex assay. The latex preparation provides a useful, rapid diagnostic tool for assaying small numbers of samples or as an emergency test.

Sudden infant deaths and clear weather in a subtropical environment

Particulate pollution levels were found to decrease, on average, over the 10-day period preceding SIDS incidence in a study of 369 cases over 15 years in Brisbane, Australia. This unexpected association could not be explained by correlations between daily pollution levels and daily precipitation, wind velocity, air temperature or cloud. Of the meterological variables studied, which might have given rise to the particulate-SIDS associations, only visibility showed associations with SIDS incidence. Average visibility increased prior to SIDS in both summer and winter cases. It is hypothesised that these findings may be due to either direct effects of light, or due to increased outdoor exposure of infants and/or to changes in parental behaviour during clear weather.

Growth From Birth to 20 Days in the Elephant Seal, Mirounga-Leonina, at Macquarie-Island

Recent investigations by members of Australian National Antarctic Research Expeditions to Macquarie I. have revealed a decrease in the elephant seal population there of approximately 50% over the last 36 years. Lower birth weights and/or slower growth during the lactation period might explain this decrease. To test this hypothesis, growth of pups was studied from birth to 20 days during the 1984 and 1985 breeding seasons; these results were compared as far as possible with similar results for the 1956 and 1965 seasons. Average birth weight has not changed significantly over the last 20 years; it is suggested that if food supply were a major factor in the reduction of the elephant seal population, then birth weights in 1985 would have been lower than those in 1956. At birth, male pups were 7% (3 kg) heavier than female pups in 1985. Results from previous years suggest that this is probably normal in this seal. The weight of pups near weaning (20 or 21 days old) is shown to be significantly less in 1984 and 1985 than 1965, but this may be explained by differences in methodology. It is concluded that, on the evidence available, the pattern of pup growth on Macquarie I. has not altered significantly with time, but more work is needed to reach a clear conclusion.

An Aerial Survey of Feral Pigs and Emus in Southeastern Queensland

Aerial surveys of feral pigs in the Goondiwindi region of Queensland showed an overall observed density of about 1 per square kilometree. On mature wheat crops in October, up to four feral pigs per square kilometre were seen amidst substantial crop damage. Emus were less abundant and seen more evenly over all habitats at an average of 0.3 per square kilometre. Factors affecting sightability are discussed.

Factors Affecting the Numbers of Culicoides (Diptera, Ceratopogonidae) in Traps in Coastal Southeast Queensland, With Particular Reference to Collections of Culicoides-Subimmaculatus in Light Traps

Hourly light-trap collections, made at Tingalpa Creek, south-east Queensland, on 101 nights over 2.5 years from 30 min before to 3.5 h after sunset, caught 45 414 Culicoides, largely C. subimmaculatus (63%). Sinusoidal curves for annual, lunar and tide cycles, and linear maximum tide height were fitted to logarithmically transformed data. Annual cycles accounted for 44-71% of the between-day variation in catch of C. austropalpalis, C. cordiger, C. henryi, C. histrio, C. longior, C. marmoratus and C. subimmaculatus. Catches of C. subimmaculatus were inversely related to maximum tide height. Catches of the other species were independent of tide. Linear effects of wind speed, temperature, saturation vapour pressure deficit (VPD), cloud cover and time on within-day variation were analysed. Catches of all seven species were inversely related to wind speed but not to the same degree, were independent of VPD and cloud cover, and varied in their dependence on temperature and time. Moonlight increased truck-trap catches of C. subimmaculatus in the third hour after sunset. Activity of female C. subimmaculatus throughout the diel (five trials) varied with the method of assessment: bait, truck trap or light trap. Collections were age graded. All seven grades were caught in the light trap, and empty females dominated the truck trap.

Weekly variations in body weight and plasma testosterone concentrations in the captive male possum, Trichosurus vulpecula

The possum is a seasonally breeding marsupial which gives birth in Queensland from March through to September. To ascertain whether this seasonality in breeding is manifest in the male reproductive system, body weight and plasma testosterone concentrations were examined in five possums. Plasma testosterone concentrations fluctuated throughout the year and a seasonal cycle was observed, with a peak in testosterone concentration in March and a nadir in September. Body weights fluctuated in a similar manner. Statistical analysis suggested that the annual plasma testosterone profile correlated well with the rate of change of daylength.

Correcting for Incomplete Sighting in Aerial Surveys of Kangaroos

Kangaroo density estimates derived from aerial survey depend on the method of deriving sightability correction factors developed by Caughley. The method depends on five assumptions, some concerned with the mathematical properties of a model for sightability probabilities and others with deriving correction factors from this model. All these assumptions can be criticized. In addition, evidence on the performance of the method does not suggest that it is accurate. Published density estimates are less precise than indicated, and may include biases due to factors not considered in the correction factors used, e.g. seasonal conditions, time of day, and species differences. At present, no satisfactory alternative method of correction exists but, because inaccuracies may be large, continued use of the method requires much greater caution than has previously been shown. This is particularly relevant where density estimates are used to determine management procedures.

Calcitonin cell population and distribution in the thyroid gland of the rat

Calcitonin-containing cells (C cells) were identified in male Wistar white rats using an immunoperoxidase technique. They occupied a central position within the thyroid; very few were found peripherally, inferiorly, and superiorly; and none were present in the isthmus. The number of calcitonin-containing cells present per gram of body weight increased with age up to 70 days and had declined by 100 days. Determining the true total C-cell count through the entire thyroid is a very laborious procedure. However, a simple estimate of this total count can be made; the total number of C cells in every tenth section (6 microns) of thyroid was found to be highly correlated with the weight of the animal expressed as an allometric function. A better estimate can be derived from counts of just three sections: the tenth, twentieth, and thirtieth after the section of greatest cross sectional area.

Seasonal variations in plasma testosterone concentrations in the male marsupial bandicoot Isoodon macrourus in captivity

Although bandicoots in Queensland mate throughout the year, the majority of births occur in late winter and spring. To ascertain whether this seasonality in mating is manifest in the male reproductive system; body weight, testes size, and plasma testosterone concentration were examined in eight bandicoots throughout the year. The size of the testes increased with age in all bandicoots and there was no evidence of seasonal variation. Plasma testosterone concentrations fluctuated from 0.1 to 70.0 ng/ml and a seasonal cycle was observed, with a nadir in concentrations in March and a peak in September. The peak in testosterone concentration coincided with the period of the year when the majority of births occurred. Subsequent statistical analysis suggested that the annual plasma testosterone profile correlated well with the rate of change of day length.

Norms for hand grip strength

Norms for hand grip strength of healthy children are presented. Sex and age specific centiles for age 5 to 18 years have been determined using a portable strain gauge dynamometer with an accuracy of 0.5 N. The test group comprised 1417 healthy, urban school children from a middle class suburb of Brisbane. Mean maximum grip strength (of four tests, two with each hand) and mean peak grip strength (best of four tests) were recorded. Mean values of peak grip strength were 10 to 15% higher than the average maximum grip in all age groups. At all ages girls had a reduced grip strength compared with boys and although boys manifested a continual, approximately linear increase in grip strength through all age groups, girls manifested an approximately linear increase up to 13 years after which mean hand grip usually remained constant. By the age of 18 years boys had a mean grip strength some 60% higher than girls. Correlations with height and weight are also presented. "Handedness' influenced grip strength and was most noticeable in children aged over 10 years. The clinical use of hand grip strength centiles for the early indication of neurological and muscular disorders and for following the natural history of neuromuscular disease is discussed.

The uniformity of growth within the litter of the marsupial, Isoodon macrourus

The amount of information concerning reproduction in eutherian mammals differs markedly with that available for marsupials. There is at present a good understanding of growth in the eutherian litter after birth but the respective information for litter bearing marsupials has still to be obtained. In this study the growth of the young bandicoot after leaving the pouch was examined. Each of the monitored young, 38 females and 12 males, was weighed weekly and a growth rate estimated for the ages 65 to 105 days. Although these growth rates varied from 3.80 to 9.50 g/days and large variations in growth rate were observed between litters, the findings suggest that development within a pouch, in contrast to uterine development, gives rise to a litter which is more uniform in size.

Delayed vascular reactivity to ischemia in diabetic microangiopathy

To investigate vascular responses in insulin-dependent diabetic patients both with and without retinopathy, we have assessed vasodilation by forearm transcutaneous pO2 measurement after 10 min of ischemia produced by a sphygmomanometer cuff. Diabetic patients with proliferative retinopathy had a delayed vasodilatory response at 60 s (mean +/- SD pO2 = 9 +/- 3 mm Hg) compared with those having diabetes without retinopathy (15 +/- 4 mm Hg, P less than 0.01) and matched normal subjects (14 +/- 4 mm Hg, P less than 0.01). Recently diagnosed insulin-dependent diabetic patients had a very similar response (15 +/- 5 mm Hg) to matched normal subjects (15 +/- 3 mm Hg). The diminished vascular reactivity may be a consequence of microangiopathy and neuropathy, although patients with an impaired vascular response might be particularly at risk from the development of capillary closure.

Correlations between Breeding Activity in the Marsupial Bandicoots and some Environmental Variables

The percentage of lactating females in wild populations of bandicoots, observed during each month of the year, has been correlated with the environmental variables of daylength, rainfall and temperature, and derivatives of these variables. Breeding activity recorded in four studies carried out in each of the eastern Australian states, Tasmania, Victoria, New South Wales and Queensland, was examined. In all four studies, the proportion of lactating females was strongly correlated with the rate of change of minimum temperature, although in some studies rainfall and daylength showed some small additional associations. An analysis of the number of births in a housed captive population in Queensland similarly showed a stronger association of numbers of births to rate of change of minimum temperature than to any other environmental variable examined.

Variation in peripheral progesterone concentrations with environmental temperature in ewes on Days 7 and 11 of the oestrous cycle

Progesterone concentrations in peripheral plasma samples on Days 7 and 11 of oestrous cycles throughout the breeding season showed a negative relationship to the mean minimum environmental temperature for the Days 0-7 and 0-11 respectively of that cycle during which the samples were collected.

Theoretical analysis of a method for determining the pattern of macromolecular synthesis during the cell cycle

The dual-labelling centrifugal-elutriation method has been extensively used to study patterns of macromolecular synthesis and accumulation in the yeast cell cycle. Cells are long-term labelled with a radioactive precursor for about 1.5 cycles (a measure of macromolecular mass), then pulse-labelled with a precursor containing a different radioactive isotope for the final 0.1 cycle (a measure of rate of synthesis). Harvested cells are fractionated into cell cycle stages by centrifugal elutriation, and changes in pulse: long-term labelling during the cycle determined. This pattern of change is compared with theoretical changes in rate: mass calculated for various patterns of synthesis. Using this method, it has been suggested that rates of synthesis and accumulation of several types of RNA and protein all increase exponentially through the cycle. In contrast, experiments using synchronous cultures or zonal centrifugation for cell cycle analysis have suggested other synthetic patterns, including periodic doubling in rate in each cycle. In this paper we analyse whether the dual-labelling, centrifugal-elutriation method is capable of discriminating between exponential and periodic rate-doubling patterns. Three possible sources of imprecision in the method and its application are examined. (1) Theoretical rate: mass curves have been simulated for macromolecules with a wider range of properties than previously considered. It is shown that for some important classes, such as messenger RNAs, with turnover rates in the range measured experimentally, and proteins, differences between rate: mass curves for exponential and periodic rate-doubling models are considerably smaller than previously suggested. (2) Long-term labelling is shown to be an accurate measure of macromolecular mass, but pulse-labelling can be inadequate as a measure of rate of synthesis. The error is greater with RNAs with faster turnover, and again reduces the ability of the method to discriminate exponential and periodic rate-doubling models of synthesis. The error is greater with RNAs with faster turnover, and again reduces the ability of the method to discriminate exponential and periodic rate-doubling models of synthesis. (3) Imperfections in cell cycle fractionation by centrifugal elutriation are examined, and by computer simulation it is shown that these also reduce the ability of the method to distinguish between the two models of synthesis. The three sources of imprecision are cumulative. It is concluded from simulation analyses that the differences between exponential and periodic rate-doubling patterns analysed by the method would be so small as to be almost impossible to establish against the background of error in experimental measurement. We therefore suggest that in practice, the dual-labelling centrifugal-elutriation method is unable to discriminate between the exponentially increasing and periodic rate-doubling models. The mathematical treatment developed in this paper should be applicable to analysis of other methods and cell cycle events.

Intravenous Imferon masquerading as an acute hemolytic transfusion reaction

The case of a 74-year-old woman with a history of chronic iron deficiency anemia requiring transfusion is reported. Shortly after receiving intravenous iron-dextran, the patient was transfused with two units of crossmatch compatible packed red blood cells and subsequently experienced severe racking chills associated with mild elevation of temperature. In the evaluation of this febrile reaction, her serum exhibited a distinct red-brown discoloration which was interpreted as free hemoglobin. Laboratory studies performed to evaluate the possibility of acute intravascular hemolysis were all within normal limits. Subsequent investigation revealed that the color of the recipients serum was due to iron-dextran. Caution is urged in the evaluation of patients for hemolytic transfusion reactions who have been administered intravenous iron-dextran, since the drug imparts a red-brown tinge to the plasma which may be misinterpreted as free hemoglobin.

Does transfusion using a syringe infusion pump and small-gauge needle cause hemolysis?

Hemolysis of two- and nine-day-stored sedimented red blood cells (hematocrit 65%), infused by a constant-rate syringe delivery pump through a 25-gauge needle was investigated. Fifteen-ml aliquots of blood were pumped through the system at flow rates of 10.6, 20.5, and 70 ml/hour. Plasma-free hemoglobin and potassium were measured and compared to controls. Significant red blood cell hemolysis occurred during passage through this infusion system, and the amount of hemolysis was greater with nine-day-stored cells. These cells showed more hemolysis with slower flow rates, but the two-day-stored cells were not affected by rate of flow.

Potassium: aldosterone relationships in pregnant ewes and chronically cannulated ovine fetuses

As maternal hyperkalemia quickly induces fetal hyperkalemia, it was decided to investigate the effect of small elevations of plasma [K+] on the peripheral blood aldosterone concentration in chronically catheterized ovine fetuses and to compare this response to that obtained in the adult ewe both pregnant and nonpregnant. Fol elevations of plasma [K+] of 0.1 to 0.3 mmole/liter blood aldosterone concentrations were elevated by 6.7 +/- 4.9 (9) ng/dl in nonpregnant sheep, 6.3 +/- 5.0 (6) in pregnant ewes, but only 0.3 +/- 1.7 (4) in fetal sheep. For increments in plasma [K+] of 0.4--1.0 mmole/liter aldosterone increments in nonpregnant ewes were 9.5 +/- 4.5 (4) ng/dl compared with 10.1 +/- 4.7 (5) in pregnant ewes and 1.5 +/- 2.6 (7) in fetuses. There was no obvious correlation between the age of the fetus and the response to increased plasma [K+]. In effect, the blood aldosterone concentration of the fetus was not elevated by increasing plasma plasma [K+].

SPECULATION

The ovine fetus is not able to cope with hyperkalemia by increasing blood aldosterone concentration. Until the fetus is close to term, hyperkalemia may jeopardize the pregnancy by causing placental hemorrhages.

Initial Observations of the Pioneer Venus Orbiter Solar Wind Plasma Experiment

Initial results of observations of the solar wind interaction with Venus indicate that Venus has a well-defined, strong, standing bow shock wave. Downstream from the shock, an ionosheath is observed in which the compressed and heated postshock plasma evidently interacts directly with the Venus ionosphere. Plasma ion velocity deflections observed within the ionosheath are consistent with flow around the blunt shape of the ionopause. The ionopause boundary is observed and defined by this experiment as the location where the ionosheath ion flow is first excluded. The positions of the bow shock and ionopause are variable and appear to respond to changes in the external solar wind pressure. Near the terminator the bow shock was observed at altitudes of approximately 4600 to approximately 12,000 kilometers. The ionopause altitutde ranged fromn as low as approximately 450 to approximately 1950 kilometers. Within the Venus ionosphere low-energy ions (energy per untit charge < 30 volts) were detected and have been tentatively idtentified as nonflowing ionospheric ions incident from a direction along the spacecraft velocity vector.

Analysis of the significance of a periodic, cell size-controlled doubling in rates of macromolecular synthesis for the control of balanced exponential growth of fission yeast cells

Mutant strains of the fission yeast Schizosaccharomyces pombe are available which divide at smaller mean sizes than wild type. Earlier work by the present authors has shown that all these strains double their rates of polyadenylated messenger RNA synthesis as a step once in each cell cycle. The smaller the cell, the later in the cycle is the doubling in rate of synthesis. Strains of all sizes, however, double their synthetic rate when at the same threshold size. We show here that the differences in cell cycle stage of doubling in rate of polyadenylated messenger RNA synthesis are enough to explain the reduced mean steady state polyadenylated messenger RNA contents of the smaller strains. The cell size-related control over doubling in rate of synthesis is also shown to maintain the mean polyadenylated messenger RNA content as a constant proportion of cell mass, irrespective of cell size. This control thus allows cells to maintain balanced exponential growth, even when absolute growth rate per cell is altered by mutation. It is also shown that the concentration of polyadenylated messenger RNA itself could act as a monitor of the threshold size triggering the doubling in rate of synthesis in each cell cycle.

Regulation of amniotic fluid volume and composition in the ovine fetus

To determine the role of fetal swallowing in the control of amniotic fluid volume and composition and fetomaternal sodium transport, 4 ovine fetuses of 101--129 days' gestation had their esophagi surgically occluded. Amniotic and fetal vascular cannulas were implanted at the same time in these fetuses and in four intact controls. There was no difference between the amniotic sodium or potassium of these two groups over the next 3 weeks, at which time cesarean section was performed and the volume of amniotic fluid measured. Hydramnios did not result from esophageal atresia. Twenty-four hours after injection of 24Na into the amniotic fluid, the percentages of the dose in the fetal/maternal compartment were similar in intact and esophagus-ligated fetuses.

Cure of intractable watery diarrhoea by excision of a vipoma

A 56-year-old man suffered unexplained watery diarrhoea for 5 years which ultimately produced quadraparesis due to serve potassium depletion. All investigations were negative until demonstration of elevated plasma vasoactive intestinal peptide (VIP) indicated the presence of a vipoma. Removal of the VIP-producing tumour tissue--an adrenal ganglioneuroma--resulted in complete cure. Plasma VIP measurement is thus a valuable diagnostic screen in such cases and can be used to predict prognosis and to guide further therapy.

Magnitude, dose-requirement and mode of development of tachyphylaxis to suxamethonium in man

Tachyphylaxis to suxamethonium infused at a constant rate was studied in 15 surgical patients under enflurane-nitrous oxide-oxygen anaesthesia. The compound electromyographic response of the adductor pollicis muscle to stimulation of the ulnar nerve was monitored. A short-lasting and a long-lasting nearly steady state were observed in Phase I and in Phase II, respectively, during both of which a constant infusion resulted in a constant block. Tachyphylaxis occurred during the transition of phases, beginning after infusion of 1.4 +/- 0.6 (SD) mg kg-1 of suxamethonium, and 36 +/- 14 (SD) minutes of exposure. Tachyphylaxis peaked after 2.6 +/- 1.3 (SD) mg kg-1, and 72 +/- 38 (SD) minutes of exposure. The maximum gain in neuromuscular transmission from the initial maintenance level of block as the result of tachyphylaxis was 53 +/- 24 (SD) % of the control. The results are thought to reconcile previously reported conflicting clinical observations on tachyphylaxis.

Neuromuscular facilitation during train-of-four and tetanic stimulation in healthy volunteers: observations with half-refractory paired responses

The compound electromyographic response of the thenar musculature was elicited by supramaximal stimulation of the ulnar nerve in 12 awake healthy volunteers. The half-refractory period of the neuromuscular transmission was determined. Twin stimuli separated by the half-refractory interval were repeated as a unit at 2 Hz and at 50 Hz. Thus two trains of responses, one beginning with a maximal response, the other with a half-maximal response, were obtained with each frequently of stimulation. Marked facilitation of the electromyographic response began with the train of stimulation, especially with tetanic stimulation. A secondary fade occurred occasionally. These changes were more remarkable in the train of half-refractory responses. We conclude that nerve stimulation facilitates neuromuscular transmission and deduce that the characteristic fade observed with a curariform block, rather than being an uncovered physiological phenomenon, is caused by tubocurarine and related drugs.