Pathological studies of wobbly possum disease in New Zealand brushtail possums (Trichosurus vulpecula)

Following an outbreak of wobbly possum disease in a colony of brush tail possums (Trichosurus vulpecula), the disease was established experimentally in captive possums by inoculating the animals intraperitoneally with tissue homogenates. Crude tissue homogenates of liver remained infectious after freezing at -75 degrees C or filtration through a 0.22 micron filter. The disease was characterised by docility, incoordination, loss of balance and wasting. Fifteen of 16 infected animals had to be euthanased owing to the severity of clinical signs. Cachexia was the only change observed postmortem. Histology revealed widespread perivascular infiltrations with plasma cells and lymphocytes which were severe in the liver and kidney and moderate to mild in a variety of other tissues, including skeletal and cardiac muscle. Changes in the brain consisted of a mild to moderate mononuclear perivascular cuffing. Most of the animals had small to large numbers of circulating nucleated red blood cells and eosinopenia when they were euthanased. There was a consistent decrease in serum albumin concentration and an increase in serum globulins, which resulted in a decreased albumin:globulin ratio. Virus-like particles were observed in preparations of liver from two animals; they appeared to be spherical or icosahedral and were 45 nm in diameter.     

A light microscopic study of oogenesis in the brushtail possum Trichosurus vulpecula

4-Methylquinoline (4-MeQ) showed an extraordinarily potent mutagenicity when compared to quinoline and isomeric methylquinolines. The major metabolite of 4-MeQ was 4-hydroxymethylquinoline, which was not mutagenic under the assay condition employed. Deuteration of the methyl group of 4-MeQ resulted in a decrease in the amount of the hydroxymethyl metabolite and an increase in mutagenicity, indicating that hydroxylation of the substituent methyl group is a detoxication process. A 3-chloro derivative of 4-MeQ was proven to be non-mutagenic. 4-Ethyl-quinoline, as well as 4-hydroxymethylquinoline, was much less mutagenic than 4-MeQ. Taking account of the structure-mutagenicity relationship, a possible mechanism is proposed for the potent mutagenic potential of 4-MeQ.     

Ontogeny of thyroid hormone receptors in the brushtail possum (Trichosurus vulpecula)

Exercise electrocardiogram (ECG) has a high rate of false negative results in comparison with simultaneously performed thallium-201 perfusion scintigraphy, particularly in patients with single-vessel coronary artery disease, low exercise workload, inadequate heart rate rise, and resting ECG abnormalities. We present the case of a patient in whom thallium-201 SPECT scintigram revealed equally extensive and severe myocardial ischemia in two myocardial planes opposite each other. The accompanying exercise ECG did not disclose ischemic changes despite the adequacy of heart rate rise in this patient with severe right and left anterior descending coronary artery disease. We propose, as an explanation for this phenomenon, that in this patient the ischemic ST-segment vectors of equal magnitude and direction but of opposite sense, generated during stress, cancelled each other ("ischemic ST-segment counterpoise"), thus rendering the exercise ECG normal.     

The role of maternal thyroid hormones on the development of the brushtail possum, Trichosurus vulpecula

Thyroxine (T4) is a vital hormone for the development of mammals. To determine the role of maternal thyroid hormones on organ development, methimazole, an inhibitor of T4, was first administered via a minipump to 13 mothers with pouch young between days 10 and 80 post partum for 28 days. Three young survived and 10 of the young died at 104.0 +/- 10.8 days post partum (mean, SEM). Methimazole was then administered for 28 days to 6 lactating adult possums with pouch young at day 20 post partum. The effects of this treatment on the maternal plasma concentrations of T4 were monitored and the development of the lung, kidney and brain of the young were examined at day 90 post partum. There was no difference in the morphology of the lung, kidney and brain of pouch young at day 90 post partum whose mothers were treated with methimazole or saline. Thus methimazole administered to lactating possums for a short period early in lactation can cause the demise of the young about day 100 post partum although the cause of death is unknown. It is possible that the development of the central nervous system or some other vital organ has been inhibited, this altered state not being apparent morphologically. Nevertheless the marsupial appears to be similar to the eutherian in its requirement for thyroxine for normal development. However whereas this requirement is apparent during fetal development and around the time of birth in eutherians thyroxine is of importance during pouch development in marsupials.     

Purification and characterisation of hepatic glutathione transferases from a herbivorous marsupial, the brushtail possum (Trichosurus vulpecula)

In 1994, as part of their participation in the University of North Carolina Alumni Heart Study, 1101 women aged 45-51 years answered questions about their menopausal status and current use of hormone replacement therapy (HRT). Little is known about the use of HRT in younger women. We were interested in determining both patterns of HRT use and patient characteristics associated with HRT use in this cohort of women approaching the average age of menopause. After excluding women with breast, endometrial, and ovarian cancer, we studied 1080 women. These women identified themselves as: "There is no indication that I am near menopause" (stage 1, n = 326), "I think I may be close to or in the beginning stages of menopause but am not sure" (stage 2, n = 410), "I have begun menopause" (stage 3, n = 202), and "I have been through menopause" (stage 4, n = 142). The overall rate of HRT use was 22% (0% in stage 1, 8% in stage 2, 52% in stage 3, and 76% in stage 4). Both patterns of HRT use and patient characteristics associated with HRT use differed based on the woman's perception of her menopausal stage. In logistic regression models, where HRT use was the outcome variable, independent predictors of HRT use included stage of menopause, having had a hysterectomy, having had a bilateral oophorectomy, no family history of breast cancer, having had a pelvic examination in the last year, being married, and not participating regularly in physical exercise. A woman's perception of her stage in the process of reproductive aging correlates with her use of HRT. Informed decision making about HRT use should be tailored to the individual's perception of her menopausal stage.     

cDNA sequence analysis, gene expression and protein localisation of the inhibin alpha-subunit of Australian brushtail possum (Trichosurus vulpecula)

A reliable source of human neural tissue would be of immense practical value to both neuroscientists and clinical neural transplantation trials. In this study, human precursor cells were isolated from the developing human cortex and, in the presence of both epidermal and fibroblast growth factor-2, grew in culture as sphere shaped clusters. Using traditional passaging techniques and culture mediums the rate of growth was extremely slow, and only a 12-fold expansion in total cell number could be achieved. However, when intact spheres were sectioned into quarters, rather than mechanically dissociated, cell cell contacts were maintained and cellular trauma minimised which permitted the rapid and continual growth of each individual quarter. Using this method we have achieved a 1.5 million-fold increase in precursor cell number over a period of less than 200 days. Upon differentiation by exposure to a substrate, cells migrated out from the spheres and formed a monolayer of astrocytes and neurons. No oligodendrocytes were found to develop from these human neural precursor cells at late passages when whole spheres were differentiated. This simple and novel culture method allows the rapid expansion of large numbers of non-transformed human neural precursor cells which may be of use in drug discovery, ex vivo gene therapy and clinical neural transplantation.     

Timing of zona pellucida formation in the tammar wallaby (Macropus eugenii) and brushtail possum (Trichosurus vulpecula)

The zona pellucida (ZP) is an extracellular coat that surrounds the mammalian egg, and serves as the primary recognition site for fertilizing spermatozoa. The timetable of ZP formation was examined in two marsupials, the tammar wallaby (Macropus eugenii) and the brushtail possum (Trichosurus vulpecula) using conventional histological methods, immunofluorescence and electron microscopy. Ovaries from tammar wallaby pouch young less than 80 days of age contained only primordial follicles with a single layer of flattened granulosa cells. There was no evidence of ZP formation until 98 days, when a small number of eggs surrounded by a single layer of cuboidal granulosa cells had a ZP detectable by periodic-acid-schiff staining and rabbit anti-pig ZP polyclonal antibody labelling. Possum ovaries at 108 and 114 days also contained a small number of eggs with a ZP and a single layer of cuboidal granulosa cells. The antibody also labelled the peripheral cytoplasm of oocytes at this stage and, occasionally, the granulosa cells. Antral follicles were first detected at 144 days in the wallaby and 125 days in the possum, and always contained an egg surrounded by a ZP. Ovaries from 147, 158, 165, 181, 184 and 210-day-old tammar wallabies contained a range of follicle types from primordial through early antrum formation. Electron microscopy confirmed observations made at the light microscope level. The ZP was first detectable in small primary follicles with a single layer of cuboidal granulosa cells in areas where microvilli had begun to form on the egg plasma membrane. Immunogold labelling indicated the egg cytoplasm as the origin of the ZP proteins. The ZP completely filled the space between the egg and the adjacent granulosa cells in preantral follicles, so that there was no perivitelline space.     

SmI cortical barrels in an Australian marsupial, Trichosurus vulpecula (brush-tailed possum): structural organization, patterned distribution, and somatotopic relationships

This study reports on the cerebral cortex of an Australian marsupial, Trichosurus vulpecula (brush-tailed possum). It consists of an analysis of layer IV of somatosensory cortex in tangential sections of flattened specimens and in oblique radial sections stained to show Nissl substance or myelin, or tested for succinic dehydrogenase. It includes results of electrophysiological mapping experiments that ascertained the somatotopic significance of the cytoarchitecture of this cortical region. Layer IV has two interlocking cytoarchitectural fields: one granular (the barrelfield, comprising cell-dense barrels 150 to 500 microns in diameter) and one dysgranular. Only neurons within the granular field responded to light cutaneous stimulation. In the barrelfield cell-sparse septa (about 100 microns wide), low in succinic dehydrogenase activity and containing many radial myelinated axons, separate adjoining barrels. Possum barrels are "solid," lacking the prominent hollows characteristic of most rodent barrels. In some specimens three to five small neuronal "lobules" may constitute each large barrel. In tangential sections the size, shape, and arrangement of barrels combine to form a histological caricature of the possum's body, especially of the face and forepaw. Six rows of "mystacial barrels" are homeomorphic to the six rows of large mystacial vibrissae, and "forepaw barrels" are homeomorphic to the glabrous palmar and apical digital pads. Correlating cortical recording sites and receptive fields confirmed that individual barrels represent specific cutaneous regions. These results show that the cortical barrels of brush-tailed possums are remarkably similar to those of rodents, in structure, arrangement, and functional significance.     

Isolation, characterization and radioimmunoassay of luteinizing hormone in the brushtail possum

Luteinizing hormone (LH) was purified from brushtail possum (Trichosurus vulpecula) pituitary glands. The purification procedure consisted of ammonium sulfate precipitation followed by triazinyl-dye chromatography, hydrophobic interaction chromatography and gel filtration. A yield of 10 microg LH g-1 pituitary with a recovery of 20% was obtained from 1400 pituitary glands (20.3 g). Contamination with possum follicle-stimulating hormone (FSH) was < or =0.05%. The amino acid analysis and the N-terminal sequencing for 10 cycles revealed close homology with LH from other mammals. Minor amounts of LH that had been truncated near the N-terminal were also detected. No contaminating proteins were found by amino acid sequencing. The potency of possum LH was 20% that of ovine LH in a receptor assay using possum testicular receptors and 4% that of ovine LH when bovine corpora lutea receptors were used. Possum LH was able to stimulate production of cyclic adenosine 3',5'-monophosphate by bovine granulosa cells. A radioimmunoassay (RIA) for possum LH using 125I-possum LH and an antiserum raised against ovine LH was developed. The RIA has a sensitivity of 0.15 ng mL-1, a 50% displacement of 1.9 ng mL-1 and a cross-reactivity of <0.02% against possum FSH. Plasma concentrations were 0.24+/-0.04 ng mL-1 (n = 8) and 0.39+/-0.12 ng mL-1 (n = 8) in female and male possums respectively. Administration of mammalian gonadotrophin-releasing hormone (GnRH) and chicken GnRH II stimulated increases in plasma LH concentrations in male and female possums. When comparing LH responses with administration of mammalian GnRH or chicken GnRH II, plasma LH concentrations remained elevated for a longer period of time in males than in females (P < 0.01); plasma LH concentrations also remained elevated for longer after mammalian GnRH than after chicken GnRH II (P < 0.01). Gonadectomy stimulated an increase in plasma concentrations of LH in both male (P < 0.01) and female (P < 0.05) possums. The rate of increase in plasma LH concentrations in males was faster than that in females. In summary, we have purified, partially characterized, and developed a RIA for possum LH.     

Physiological analysis of stress-induced changes in the suppressor activity of mouse T-lymphocytes

BACKGROUND: Despite their potential therapeutic benefit, the effects of cholinergic agents on anal function have been poorly investigated. AIM: To analyse the effects of neostigmine and atropine on anorectal responses to rectal isobaric distension. METHODS: This was a placebo-controlled, randomized, double-blind crossover study, performed in 12 healthy volunteers who received intravenously, on 3 separate days, neostigmine, atropine or the placebo. During each day of the experiment, seven pressure steps (ranging from 1 to 31 mmHg) in three different protocols of rectal isobaric distension (phasic, stepwise and tonic) were applied using an electronic barostat. Manometric responses of the anal canal, adaptative volumes and perception scores of the rectum were recorded. RESULTS: During stepwise distension, a significant drug effect was encountered at the anal level. No drug effect was observed on the other investigated parameters (rectal volumes and rectal perception scores) or for the other modes of distension. Compared to placebo, neostigmine significantly decreased pressures at the upper level of the anal canal for both recto anal inhibitory reflex and mean resting pressures. In contrast, atropine significantly increased pressures at the lower part of the anal canal but did not modify upper anal pressures. CONCLUSION: The present study suggests that cholinergic effects result more from an indirect action on intermediate neurotransmitters and rectal myenteric neurons, than from a direct action on anal targets.     

Lysine and glutamate transport in the erythrocytes of common brushtail possum, Tammar Wallaby and eastern grey, kangaroo

STUDY OBJECTIVE: To compare drug output from a vented nebulizer (Pari LC Jet Plus) with a traditional unvented nebulizer (Hudson 1730 T Up-Draft 11) using aerosolized tobramycin, which is frequently used in the treatment of cystic fibrosis. DESIGN: Six nebulizers of each type were filled with a 4 mL tobramycin (80 mg) solution and were driven by a compressor (Pulmo-Aide). Various inspiratory flows (VI) (0, 5, 10, 15, 20 L/min for the Pari LC Jet Plus and 0, 5, and 10 L/min for the Hudson 1730, all at 40% relative humidity) were directed through each nebulizer. Drug output was measured from changes in weight and concentration (assessed by changes in osmometry) within the nebulizer. Particle size distributions were determined by laser diffraction allowing the calculation of the amount of aerosol output in the respirable range (<5 microm). The nebulizers were first run until end-nebulization to establish total drug output and then for either 4 or 5 min to determine the rate of drug output (mg/min) before intermittent aerosol output. RESULTS: The total drug output without VI for both the unvented and the vented nebulizers was not significantly different, 55 (51, 60) mg for the Hudson 1730 vs 51 (49, 53) mg for the Pari LC Jet Plus (mean [95% confidence limits]). Inspiratory flow had no effect on the unvented Hudson 1730 nebulizer but significantly increased the rate of total drug output and the rate of drug output in the respirable range for the vented Pari LC Jet Plus nebulizer (VI=0, 3.35 [2.84, 3.85] and 1.72 [1.48, 1.96] compared with VI=20, 9.87 [9.03, 10.70] and 6.11 [5.33, 6.88] mg/min). CONCLUSIONS: These findings indicate that the increase in the rate of drug output with VI for the vented nebulizer would result in shorter nebulization times and a relative decrease in drug loss during the expiratory phase.     

Ticks, Lyme disease spirochetes, trypanosomes, and antibody to encephalitis viruses in wild birds from coastal Georgia and South Carolina

Ticks and blood samples were collected from wild birds mist-netted on St. Catherine's Island, Georgia, and at the Wedge Plantation in coastal South Carolina in 1994 and 1995. Immature stages of 5 species of ixodid ticks were recovered from 10 of 148 (7%) birds belonging to 6 species in Georgia, whereas 6 ixodid species were recovered from 45 of 259 (17%) birds representing 10 avian species in South Carolina. Borrelia burgdorferi sensu lato was isolated from 27 of 120 (23%) screened ticks (Ixodes scapularis and Ixodes minor) recovered from South Carolina birds, but from none of 16 screened ticks removed from Georgia birds. This spirochete was also isolated from 1 of 97 (1%) birds in South Carolina. In 1995, neither eastern equine encephalitis (EEE) virus nor St. Louis encephalitis (SLE) virus was isolated from any of 218 bird sera screened, but serum neutralizing antibodies were found to EEE virus in 4 of 121 (3%) sera and to SLE virus in 2 of 121 (2%) sera from South Carolina. No antibody to either virus was detected in 51 avian sera screened from Georgia. Trypanosomes (probably Trypanosoma avium) were isolated from 1 of 51 (2%) birds from Georgia and from 13 of 97 (13%) birds from South Carolina. Our data suggest that some wild birds may be reservoir hosts for the Lyme disease spirochete and for encephalitis viruses in coastal Georgia and South Carolina and that migrating birds can disperse immature ticks infected with B. burgdorferi.     

Cytochrome P450 enzyme activities in the Australian brushtail possum trichosurus vulpesula: a comparison with the rat, rabbit, sheep and chicken

630 neonates with risk factors of perinatal hearing impairment were screened of hearing loss by means of registration of transient otoacoustic emissions before discharge from the newborn nursery. Neonates were screened additionally by means of brainstem evoked response audiometry, if they had bilateral negative emissions. 810 healthy neonates were screened as control group. The investigations were carried out in incubator after the feeding of neonates. The prevalence of a bilateral negative cochlear response was 5.2% in the risk babies and 1.7% in healthy neonates. Neonates are high risk patients for hearing loss if they show craniofacial anomalies including alcohol embryofetopathy, connatal infections, or very low birth weight babies with additional risk factors. The pedaudiological control investigations of the babies with a negative bilateral cochlear response delivered in the risk group 15 cases (2.4%) with an important hearing impairment and in the healthy neonates 2 cases (0.25%) respectively. Prevalence and importance of perinatal hearing impairment explains the necessity of detection in the neonatal period.     

Iron and copper nutrition-dependent changes in protein expression in a tomato wild type and the nicotianamine-free mutant chloronerva

The nicotianamine-deficient mutant chloronerva resembles phenotypically an Fe-deficient plant despite the high accumulation of Fe in the leaves, whereas if suffers from Cu deficiency in the shoot. Two-dimensional electrophoretic separation of proteins from root tips and leaves of wild-type Lycopersicon esculentum Mill. cv Bonner Beste and the mutant grown with and without Fe showed a number of consistent differences. In root tips of the Fe-deficient wild type and the Fe-sufficient as well as the Fe-deficient mutant, the expression of glyceraldehyde-3-phosphate dehydrogenase, formate dehydrogenase, and ascorbate peroxidase was increased. In leaves of the Fe-sufficient and -deficient mutant, Cu-containing chloroplastic and cytosolic superoxide dismutase (Cu-Zn) and plastocyanin (Cu) were nearly absent. This low plastocyanin content could be restored by supplying Cu via the xylem, but the superoxide dismutase levels could not be increased by this treatment. The differences in the protein patterns between wild type and mutant indicate that the apparent Fe deficiency of mutant plants led to an increase in enzymes involved in anaerobic metabolism as well as enzymes involved in stress defense. The biosynthesis of plastocyanin was diminished in mutant leaves, but it was differentially induced by increased Cu content.     

Physiological changes in insulin resistance in human pregnancy: longitudinal study with the hyperinsulinaemic euglycaemic clamp technique

Twenty-six patients with rheumatoid disease affecting the cervical spine underwent surgical treatment for neck pain, neurological deficit, or both. Atlantoaxial subluxation (n=13), subaxial subluxation (n=7) and vertical migration of the odontoid (n=6) were treated. Arthrodesis with autologous bone was augmented with wire, Ransford loop, Hartshill rectangle or Magerl technique. Pain relief occurred in 92% of patients. Neurological deficit improved in 89% and was unchanged in the remainder. Radiographic stability was achieved in all but one patient. Posterior surgery effectively relieved pain and neurological deficit, and the complications encountered did not jeopardize the outcome.