Interaction of formaldehyde with soil humic substances: separation by GFC and characterization by (1)H-NMR spectroscopy.
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Chromatography, Gel↗
Biomedical subjects
G Shaw
Publications and source records attributed to G Shaw.
Toxicological aspects of treatment to remove cyanobacterial toxins from drinking water determined using the heterozygous P53 transgenic mouse model.
The presence of toxic cyanobacteria in drinking water reservoirs renders the need to develop treatment methods for the 'safe' removal of their associated toxins. Chlorine has been shown to successfully remove a range of cyanotoxins including microcystins, cylindrospermopsin and saxitoxins. Each cyanotoxin requires specific treatment parameters, particularly solution pH and free chlorine residual. However, currently there has not been any investigation into the toxicological effect of solutions treated for the removal of these cyanotoxins by chlorine. Using the P53(def) transgenic mouse model male and female C57BL/6J hybrid mice were used to investigate potential cancer inducing effects from such oral dosing solutions. Both purified cyanotoxins and toxic cell-free extract cyanobacterial solutions were chlorinated and administered over 90 and 170 days (respectively) in drinking water. No increase in cancer was found in any treatment. The parent cyanotoxins, microcystins, cylindrospermopsin and saxitoxins were readily removed by chlorine. There was no significant increase in the disinfection by-products trihalomethanes or haloacetic acids, levels found were well below guideline values. Histological examination identified no effect of treatment solutions except male mice treated with chlorinated cylindrospermopsin (as a cell free extract). In this instance 40% of males were found to have fatty vacuolation in their livers, cause unknown. It is recommended that further toxicology be undertaken on chlorinated cyanobacterial solutions, particularly for non-genotoxic carcinogenic compounds, for example the Tg. AC transgenic mouse model.
Acetates↗
The volatilisation and sorption of (129)I in coniferous forest, grassland and frozen soils.
129I is a potentially important radionuclide in safety assessments of proposed deep geological radioactive waste repositories due to its radiotoxicity, high mobility and long physical half-life (15.7 million years). In soils, iodine is present both in an inorganic form and in organohalide complexes, some of which are volatile under natural environmental conditions. This study has examined volatilisation, sorption and the effect of freezing on sorption and loss of (125)I (physical half-life 60.2 days), as a surrogate for (129)I, within coniferous forest and grassland soils. The results do not suggest that volatilisation from these soils is a significant pathway for the transport of (129)I. Strong and specific sorption of iodine to humic substances has been demonstrated, which is reduced at freezing temperatures. It is hypothesised that rapid sorption to soil humic substances can significantly reduce volatilisation rates. The effect of freezing conditions on iodine extractability from soils suggests a microbially mediated sorption process.
Ecosystem↗
Soil transport and plant uptake of radio-iodine from near-surface groundwater.
This paper describes a 12-month experiment designed to study the extent of upward migration of (125)I (as a surrogate for (129)I) from near-surface groundwater, through a 50-cm column of soil and into perennial ryegrass. The water table was established at a depth of 45 cm below the soil surface. By 3 months, (125)I had migrated about half way up the soil column. After this, it tended to accumulate just above this mid-point, with only very small amounts being transported to the upper 20 cm of soil. This behaviour seemed to be explained well by soil moisture and redox conditions. The experiment indicated that (125)I was mobile only within the saturated/low redox zone at the base of the soil column and accumulated in the zone of transition between anoxic and oxic soil conditions. Uptake of (125)I by the ryegrass was found to be low.
Environmental Monitoring↗
Structure and expression of the follicle-stimulating hormone receptor gene in a marsupial, Macropus eugenii.
Follicle stimulating hormone (FSH) is essential for folliculogenesis. The function of FSH is mediated through its receptor (FSHr) and modulation of the receptor is thought to be the mechanism by which the responsiveness of follicles to gonadotrophins is regulated. FSHr is alternatively spliced to produce several transcripts in all eutherian species studied. However, controversy exists over the significance of alternatively spliced transcripts. In this study, we cloned and characterised the tammar wallaby (Macropus eugenii) FSHr gene and examined its expression. Comparison of gene structure and function between marsupials and eutherians enables identification of conserved features that are likely to be of functional significance. Tammar FSHr shares 94% amino acid similarity with human FSHr and is expressed in both the adult testis and ovary suggesting a similar function for this gene in both marsupials and eutherians. Tammar FSHr undergoes alternate splicing to produce four transcripts consistent with the splice variants seen in eutherians. These results strongly suggest that alternate splicing is of functional significance in the ovary since it has remained a highly conserved character of this gene for over 100 million years of divergent evolution.
Amino Acid Sequence↗
Improved survival through the reduction of ischemia-reperfusion injury after rat intestinal transplantation using selective P-selectin blockade with P-selectin glycoprotein ligand-Ig.
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Animals↗
Phenotypic transformation of CD52(pos) to CD52(neg) leukemic T cells as a mechanism for resistance to CAMPATH-1H.
Immunotherapy utilizing CAMPATH-1H for patients with chemotherapy-refractory chronic lymphocytic leukemia has yielded encouraging results with many reports of complete remission. Here we report the outcome of two patients with CD4-positive T cell prolymphocytic leukemia treated with CAMPATH-1H. Both patients responded rapidly to treatment and subsequently developed CD4 lymphopenia. One patient remained in complete remission after 14 weeks of treatment. Serial peripheral blood flow cytometry revealed that the CD52 antigen was present throughout treatment. The other patient who was initially CD52-positive, became CD52-negative after 6 weeks of treatment, and developed progressive symptoms of T cell prolymphocytic leukemia. Immunotherapy was stopped, chemotherapy proved futile, and the patient died. This change in phenotype from CD52-positive to -negative during CAMPATH-1H therapy points out a need to develop strategies for maintaining antigenic expression during monoclonal antibody therapy.
Aged↗
Is microscopic haematuria a urological emergency?
OBJECTIVE: To determine the prevalence of urological pathology in a retrospective and prospective study of patients with microscopic haematuria attending a haematuria clinic. PATIENTS AND METHODS: Between January 1998 and May 2001, 781 patients attended the haematuria clinic; of these, 368 (47%; median age 60 years, range 18-90) had a history of microscopic haematuria, as detected by urine dipstick testing. These patients were investigated by urine culture and cytology, renal ultrasonography, intravenous urography (IVU), flexible cystoscopy, urea and electrolyte analysis, and assay of prostate specific antigen (PSA) where appropriate. RESULTS: Urine cytology showed no malignant cells in any patient with a history of microscopic haematuria. In 143 patients (39%), urine cytology showed no red blood cells and all other investigations were normal. Of the remaining 225 patients, IVU showed a tumour in one (bladder), renal stones in 15 and an enlarged prostate in two. Renal ultrasonography detected no additional pathology. Urine analysis showed one urinary tract infection. Flexible cystoscopy detected five patients with a bladder tumour (all G1pTa), two urethral strictures, five bladder stones and enlarged prostates, six enlarged prostates only, and nine red patches in the bladder, showing one patient with carcinoma in situ. No PSA levels were suggestive of prostate cancer. CONCLUSION: Patients with dipstick-positive haematuria should be re-assessed by urine microscopy before referral. As only 1.4% of patients had a malignant pathology (all noninvasive), microscopic haematuria should be regarded as a separate entity from macroscopic haematuria, and such patients do not need to be referred urgently.
Adult↗
Influence of donor age on development of gonadal tissue from pouch young of the tammar wallaby, Macropus eugenii, after cryopreservation and xenografting into mice.
Ovaries from a marsupial, the tammar wallaby (Macropus eugenii), were grafted into a eutherian recipient at known stages of development to ascertain whether normal development would occur. Xenografted ovaries from pouch young < 20 days old, before the onset of meiosis, retained few germ cells and developed tubule-like structures reminiscent of seminiferous cords. Ovaries from 50-day-old pouch young, which contain primordial follicles, developed into antral follicles and corpora lutea within the eutherian host, and produced hormones that stimulated the reproductive tract of the host. The timing of onset of antrum formation and the progress of follicle development were advanced relative to the timing of events in ovaries in situ. Frozen-thawed ovaries from 50-day-old donors developed into preantral follicles, but at a reduced rate and number. This finding shows that gonads of a marsupial species can develop as xenografts in a eutherian, forming large antral follicles. Accelerated follicular development in xenografts provides a potentially valuable model for studying the factors that control follicle development. Assisted reproduction of endangered marsupials may also be feasible using follicles from pouch young grown as xenografts in a eutherian host.
Aging↗
Effects of oestrogen treatment on testicular descent, inguinal closure and prostatic development in a male marsupial, Macropus eugenii.
This study reports the effect of oestrogen treatment on the development of the genital ducts, prostate gland, testicular descent and inguinal canal closure in male tammar wallaby young treated with oestrogen over four time spans during the first 25 days of pouch life (days 0-10, 10-15, 15-25 and 0-25) and sampled at day 50. In control males, the Müllerian ducts had regressed and the Wolffian ducts had developed into the vas deferens and epididymis. The prostate gland had formed epithelial buds extending from the ventral, lateral and posterior walls of the urethra. The testes were in the neck of the scrotum and the gubernaculum and processus vaginalis were present at the base of the scrotum. In most males treated with oestradiol from day 0 to day 25, the testes had failed to descend by day 50. The gubernaculae were long and thin. The retained Müllerian ducts formed a lateral vaginal expansion like that of normal day 50 females. The Wolffian ducts of the males treated on days 0-25 were regressed, but were present in males in the other three treatment groups. The prostate glands were hyperplastic and epithelial budding was highly invasive. Some treated males from the day 10-25 and 0-25 groups had inguinal hernias. These results demonstrate that oestrogen treatment has profound effects on the development of the internal genitalia of a male marsupial, preventing inguinal closure and interfering with testicular descent. Therefore, the tammar wallaby may provide a useful experimental model animal in which to investigate the hormonal control of testicular migration and closure of the inguinal canal.
Animals↗
Effect of an anti-androgen on testicular descent and inguinal closure in a marsupial, the tammar wallaby (Macropus eugenii).
Androgens are essential for testicular descent in eutherian mammals, but little is known about its hormonal control in marsupials. This study reports the effects of daily treatment with the anti-androgen flutamide (10 mg kg(-1)) from day 9 to day 75 after birth on the descent of the testis and inguinal closure in tammar wallabies. By day 75 after birth, the testes of control males had descended and the prostate gland was well developed. The testes of all flutamide-treated males had passed through the inguinal canal and were situated in the base of the scrotum. Three of the nine flutamide-treated males had unilateral inguinal hernias. The size of the inguinal canal, regardless of whether a hernia was present, was significantly wider than that of control males. Development of the prostate gland was significantly inhibited. By day 75 after birth, the phallus was significantly longer in control males than in females, whereas the phallus of flutamide-treated males was similar to that of control females. In flutamide-treated males, the lumbar 1 dorsal root ganglia was feminized and significantly fewer cell bodies expressed calcitonin gene- related peptide. As the anti-androgen treatment resulted in a reduction in the number of calcitonin gene-related peptide-positive cell bodies in the dorsal root ganglion supplying the genitofemoral nerve, the process of inguinal closure in tammar wallabies may be mediated by calcitonin gene-related peptide via the genitofemoral nerve, as indicated in humans. Flutamide treatment inhibited development of the prostate gland and phallus, which are both androgen-dependent structures, but it did not affect the normal descent of the testis, indicating that testicular descent can proceed when the action of androgens is blocked.
Androgen Antagonists↗
Long-term fertility control in the kangaroo and the wallaby using levonorgestrel implants.
Non-lethal management techniques are needed for overabundant captive and wild populations of macropodid marsupials for which lethal techniques are considered inappropriate and may be hazardous. The tammar wallaby, Macropus eugenii, was used as a model species to investigate the effect of s.c. levonorgestrel implants on reproduction during breeding and non-breeding seasons. Implants were tested on captive and wild populations of eastern grey kangaroos, Macropus giganteus. In both species, levonorgestrel successfully stopped reproduction by inhibiting oestrus. However, levonorgestrel did not affect the reactivation and subsequent development of blastocysts in diapause that had been conceived before treatment and it did not impair lactation, as young were reared to weaning in both species. The contraceptive effects of the implant were reversible, as removal of the implants from tammar wallabies was followed by a rapid return of fertility. Levonorgestrel implants had no apparent adverse effects on body condition in either species, although in the wild kangaroos a small increase in body condition did occur. Levonorgestrel implants are long-acting and so far have provided 48 months of contraception in the tammar wallaby and 27 months of contraception in the kangaroo, although the implants should provide contraception for more than 5 years in the kangaroo. Thus, levonorgestrel implants provide a safe, highly effective and long-term method of fertility control for macropodid marsupials and should be applicable for the management of overabundant captive and selected wild populations.
Animals↗
Characterization of steroidogenic factor 1 during sexual differentiation in a marsupial.
In eutherian mammals, such as mice and humans, steroidogenic factor 1 (SF1) plays important roles in the development of the gonad and in its steroidogenic activity. Marsupial and eutherian mammals have been evolving independently for at least 100 million years and so we were interested in comparing SF1 of a marsupial with that of eutherians. To this end, we have cloned SF1 from an Australian marsupial, the tammar wallaby. Although the amino acid sequence of SF1 is highly conserved among vertebrate species, tammar SF1 appears to have diverged less from the ancestral SF1 than have eutherian SF1 proteins. Tammar SF1 is expressed by both ovaries and testes on the day of birth, just prior to the onset of testicular differentiation, until at least 8 days after birth by which time the ovary also has begun to sexually differentiate. SF1 transcripts are localized predominantly to the pre-granulosa and Sertoli cells of the ovary and testis, respectively. In the testis SF1 transcripts are also present in the interstitial cells, although at a lower level than that which is observed in the Sertoli cells. SF1 is also transcribed in adult testis and ovary. In the adult ovary SF1 is expressed in the interstitial gland, and in the granulosa cells and theca interna of small to medium-sized antral follicles, but is not expressed in large antral follicles. Thus, although the structure of tammar SF1 is divergent from that of eutherians, its expression profile is similar, supporting a conserved role in gonadal development and steroidogenesis.
Amino Acid Sequence↗
Four casein kinase I isoforms are differentially partitioned between nucleus and cytoplasm.
The casein kinase I (CKI) family consists of at least seven vertebrate genes, some of which can be alternatively spliced. Previously, we have studied the four splice variants of the chicken CKIalpha gene. The four proteins differ only by the presence or absence of two peptides, a 28-amino-acid "L" insert in the catalytic domain and a 12-amino-acid "S" insert near the extreme C-terminus. Here cells were transfected with DNA encoding all four isoforms fused to the green fluorescent protein (GFP) and the localization of each protein was examined. We noted that the L insert includes the sequence PVGKRKR, which has the characteristics of a nuclear localization signal (NLS), and we show that the CKIalphaL and CKIalphaLS isoforms which contain this sequence are targeted to the nucleus, where a fraction becomes associated with nuclear speckles. In contrast the two isoforms lacking the L insert remain predominantly cytoplasmic. Mutation of the first lysine in the putative NLS to asparagine prevented the nuclear entry of GFP-CKIalphaL. Therefore different CKIalpha isoforms are targeted to different cellular compartments in a fashion modulated by alternate transcription and in these locations presumably phosphorylate and regulate different cellular substrates.
3T3 Cells↗
Virilization of the urogenital sinus of the tammar wallaby is not unique to 5alpha-androstane-3alpha,17beta-diol.
The androgen 5alpha-androstane-3alpha,17beta-diol (5alpha-adiol) is synthesized in testes and secreted into plasma of male tammar wallaby pouch young and appears to virilize the urogenital sinus. To provide insight into its mechanism of action, a dose response study showed that administration of 1 microg 5alpha-adiol monoenanthate per g body wt. per week for 3 weeks to 24-day-old female pouch young induced prostate bud formation equivalent to that of males of the same age. Administration of this same dose of the enanthates of testosterone, dihydrotestosterone, and 5alpha-adiol to female pouch young caused equivalent virilization of the urogenital sinus. The fact that 5alpha-adiol does not exert a unique effect, together with our earlier findings in this species that 5alpha-adiol and testosterone are converted to dihydrotestosterone in the urogenital sinus and that virilization of the urogenital sinus is prevented by the androgen receptor antagonist flutamide, suggest that 5alpha-adiol is a circulating precursor for dihydrotestosterone formation in this tissue.
Androgens↗
Investigation of Escherichia coli dimethyl sulfoxide reductase assembly and processing in strains defective for the sec-independent protein translocation system membrane targeting and translocation.
Dimethyl sulfoxide reductase is a heterotrimeric enzyme (DmsABC) localized to the cytoplasmic surface of the inner membrane. Targeting of the DmsA and DmsB catalytic subunits to the membrane requires the membrane targeting and translocation (Mtt) system. The DmsAB dimer is a member of a family of extrinsic, cytoplasmic facing membrane subunits that require Mtt in order to assemble on the membrane. We show that the MttA(2), MttB, and presumably MttA(1) but not the MttC proteins are required for targeting DmsAB to the membrane. Unlike other Mtt substrates such as trimethylamine N-oxide reductase, the soluble cytoplasmic DmsAB dimer that accumulates in the mtt deletions is very labile. Deletion of the mttA(2) or mttB genes also prevents anaerobic growth on fumarate even though fumarate reductase does not require Mtt for assembly. This was due to the lethality of membrane insertion of DmsC in the absence of the DmsAB subunits. In the absence of DmsC, DmsAB accumulates in the cytoplasm. A 45-amino acid leader on DmsA is removed during assembly. Processing does not require DmsC but does require Mtt. Translocation of DmsAB to the periplasm is not required for processing. The leader may be cleaved by a novel leader peptidase, or the long DmsA leader may traverse the membrane through the Mtt system resulting in cleavage by the periplasmic leader peptidase I followed by release of DmsA into the cytoplasm.
Arginine↗
Photocatalytic degradation of the cyanotoxin cylindrospermopsin, using titanium dioxide and UV irradiation.
Cylindrospermopsis raciborskii produces the cyanotoxin cylindrospermopsin, which is commonly found in SouthEast Queensland water reservoirs, and has been responsible for the closure of these reservoirs as a source of drinking water in recent times. Thus, alternative more effective treatment methods need to be investigated for the removal of toxins such as cylindrospermopsin. This study examined the effectiveness of two brands of titanium dioxide under UV photolysis for the degradation of cylindrospermopsin. Results indicate that titanium dioxide is an efficient photocatalyst for cylindrospermopsin degradation. The titanium dioxide (TiO2), brand Degussa P-25 was found to be more efficient than the alternate brand Hombikat UV-100. There was an influence from solution pH (4, 7, and 9) with both brands of titanium dioxide, with high pH resulting in the best degradation rate. Importantly, there was no adsorption of cylindrospermopsin to titanium dioxide particles as seen with other cyanotoxins, which would adversely influence the degradation rate. Degradation rates were not influenced by temperature (19-34 degrees C) when P-25 was the source of TiO2, some temperature influence was observed with UV-100. Dissolved organic carbon concentration will reduce the efficiency of titanium dioxide for cylindrospermopsin degradation, however the presence of other inorganic matter in natural waters greatly assists the photocatalytic process. With minimal potentially toxic by-product formation expected with this treatment, and the effective degradation of cylindrospermopsin, titanium dioxide UV photolysis is a promising speculative alternative water treatment method.
Alkaloids↗
Specific association of 36Cl with low molecular weight humic substances in soils.
Soils initially contaminated with 36Cl in the chloride form were subjected to solid-liquid extractions using a variety of reagents including deionised water and 1 M sodium hydroxide (NaOH). 1 M NaOH was found to result in the greatest recovery of 36Cl from the soils, a result which provided initial evidence that radioactive chlorine became attached to humic substances present naturally within the soils. Deionised water and 1 M NaOH extracts were subjected to analysis involving separation by gel filtration chromatography (GFC). It was found that 36Cl in 1 M NaOH extracts associated preferentially with low molecular weight (LMW) fractions of humic substances whereas, in deionised water extracts, 36Cl appeared to be present exclusively in the chloride form. Previous literature evidence, mainly from highly organic forest soils, suggests that conversion of stable chlorine from chloride to organic forms can occur as a result of biological action. The present paper also presents good evidence for the specific attachment of stable chlorine (37Cl) to a LMW humic fraction, again demonstrated using GFC separation. Current risk assessments of the deep geological disposal of solid radioactive wastes containing 36Cl typically assume a very low degree of sorption based on the notion that the predominant environmental species of radiochlorine is chloride. This paper concludes with a brief discussion on the implications of organochlorine formation in the biosphere for assessment of the radiological impact of deep geological disposal of solid radioactive wastes.
Adsorption↗