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Biomedical subjects

S Roberts

Publications and source records attributed to S Roberts.

At least 55 records · Page 3Linked to original sources
PubMed2003

Use of active barriers to reduce eutrophication problems in urban lakes.

Excessive concentration of phosphorus is one of the main causes of algal blooms and eutrophic conditions in lakes. In many urban lakes, it appears that a large proportion of the phosphorus in the water column comes from the sediments, particularly when these are anaerobic. Sub-aqueous capping is a relatively new method that has become an attractive option for isolating contaminated sediments from the environment, thus preventing or delaying the release of contaminants into surface waters. Active barrier materials (i.e. capping layers that consist of one or more reactive components) are gaining increasing attention for their greater efficiency in inactivating contaminants held in sediment layers. This paper reports laboratory bioreactor experiments to test the effectiveness of three forms of calcium carbonate (CaCO3) in reducing the release of phosphorus from anaerobic sediment from Lake Carramar, a small urban lake in Melbourne. Two of the CaCO3 active barrier materials tested proved to be quite effective, the most effective materials being the fine particle size, precipitated forms of CaCO3. Over the 20-day experimental period, a 2% layer of the German material SoCal reduced the amount of phosphorus released by almost 100 times over that occurring with no barrier. The Australian product ESCal, while not as effective as the SoCal, still reduced the phosphorus released by around 15 times that with no barrier. A finely ground Lilydale limestone was essentially ineffective in reducing phosphorus release from the sediments. A preliminary cost-benefit analysis suggests that SoCal is unlikely to be attractive for use in Australia, given the estimated application cost of around 3,800 dollars per tonne. However, although the ESCal is slightly less effective in retaining phosphorus, its potential application cost estimated at 2,000 dollars per tonne, makes it an attractive option. On the basis of these most promising preliminary results, we intend to further test the use of the ESCal. Further investigations will include: longer term laboratory studies using ESCal, optimisation of the barrier layer and methods for applying this material, mesocosms and full lake studies, and risk assessment studies to ensure there are no adverse ecological effects from its use.

Australia↗
PubMed2002

Positive and negative thought disorder and psychopathology in childhood among subjects with adulthood schizophrenia.

UNLABELLED: The New York High-Risk Project (NYHRP) is a longitudinal study of offspring of parents with schizophrenia or affective disorder and normal controls. Neuropsychological deficits had been observed at about age 9 in subjects with adulthood schizophrenia. We explored whether in these subjects, early signs of clinical schizophrenia-related symptoms, such as thought disorder or behavioral abnormalities, could also be observed. METHODS: We rated thought disorder and symptoms from videotaped interviews at age 9, using the Scale for the Assessment of Thought, Language and Communication (TLC), and the Mental Health Assessment Form (MHAF). With factor analyses we examined the structure of the ratings, and from interpretable factors, scales were assembled. MANOVAs were used to examine the effect of parental risk and adulthood psychiatric diagnosis (schizophrenia-related psychosis (SRP), major affective disorder (MAD), no disorder/other (NoDx/other)) as independent variables (IV) on thought disorder and symptoms as dependent variables. RESULTS: Global, positive and negative thought disorder, and negative symptoms were significantly higher in subjects with adulthood schizophrenia-related psychosis than both comparison groups. A significant interaction between the two IVs was effective with respect to positive thought disorder. This scale was particularly elevated among subjects with adulthood schizophrenia-related psychosis at parental risk for affective disorder (all of whom had adulthood schizoaffective disorder). CONCLUSIONS: We were able to show that global, negative and positive thought disorder and negative symptoms were present in subjects with adulthood schizophrenia already at mid-childhood, years before onset of psychosis. Further, we found a particularly high propensity to positive symptoms in subjects with adulthood schizophrenia who have also an affective component in their symptoms. This association, previously reported in acute schizophrenia, was here observed years before the first psychotic episode.

Adult↗
PubMed2002

Effects of fuel-shell mix upon direct-drive, spherical implosions on OMEGA.

Fuel-shell mix and implosion performance are studied for many capsule types in direct-drive experiments at OMEGA. The amount of mixing and the size of the mix region are inferred from charged-particle spectrometry data and confirmed with an experimentally constrained model. Measured yields and convergence ratios CR fall short of one-dimensional predictions, especially for low capsule fill pressures. CR is approximately 11 for pressures from 3 to 15 atm, in contrast to predictions of approximately 25 for 3 atm and approximately 12 for 15 atm. The performance shortfalls are likely to be caused by fuel-shell mix.

Journal Article↗
PubMed2002

Platinum agents in the treatment of osteosarcoma: efficacy of cisplatin vs. carboplatin in human osteosarcoma cell lines.

BACKGROUND: Cisplatin (cDDP), when used either alone or, more often, in combination with other agents, especially adriamycin, achieves a high response rate in osteosarcoma. Its use, however, is limited by severe nephro- and neuro-toxicity. Second generation platinum compounds, most notably carboplatin (CBDCA), have been developed in order to attempt to reduce these dose-limiting toxicities, and thus improve the therapeutic ratio. Studies evaluating the role of combination CT containing CBDCA vs. cDDP have demonstrated differing results depending on the tumor type tested and its role in the treatment of osteosarcoma has yet to be clarified. PROCEDURE: In this study, we compared the in vitro anti-tumor activity of cDDP and CBDCA in a panel of three human osteosarcoma cell lines (HOS, MG63, and U2OS). RESULTS: cDDP and CBDCA (0-20 micromol) showed marked variation in cytotoxicity among the three cell lines. EC(50) values for CBDCA in HOS and MG63 cells were approximately two-fold higher than for cDDP and the ratio of AUC(CBDCA) to AUC(cDDP) varied from 1.8 in the HOS cell line to 2.3 in the MG63 cell line. Exposure of MG63 and HOS cells to either cDDP or CBDCA (1.67 and 13.5 micromol) caused a G2/M cell cycle arrest by 24 hr. Also evident was a sub G1 peak indicative of cell death by apoptosis. U2OS cells were relatively resistant to the cytotoxic effects of both drugs, although a cell cycle arrest in response to DNA damage was observed. This suggests that unlike MG63 and HOS cells, U2OS cells have either a more efficient repair pathway for platinum-induced DNA damage or are able to evade apoptosis. Examination of apoptotic events and cellular recovery demonstrated that both an 8-16-fold higher concentration and longer treatment period for CBDCA compared with cDDP was required to produce equivalent cell death and a loss of the ability of single cell clones to form colonies in both the HOS and MG63, but not the U2OS cell line. CONCLUSIONS: Our findings suggest that CBDCA at a two- to four-fold higher concentration than cDDP has potential therapeutic activity in platinum sensitive osteosarcomas, particularly when cDDP cytotoxicity compromises therapeutic efficacy.

Antineoplastic Agents↗
PubMed2002

Binge eating disorder in extreme obesity.

OBJECTIVE: To determine whether extremely obese binge eating disorder (BED) subjects (BED defined by the Eating Disorder Examination) differ from their extremely obese non-BED counterparts in terms of their eating disturbances, psychiatric morbidity and health status. DESIGN: Prospective clinical comparison of BED and non-BED subjects undergoing gastric bypass surgery (GBP). SUBJECTS: Thirty seven extremely obese (defined as BMI > or = 40 kg/m(2)) subjects (31 women, six men), aged 22-58 y. MEASUREMENTS: Eating Disorder Examination 12th Edition (EDE), Three Factor Eating Questionnaire (TFEQ), Structured Clinical Interview for the Diagnostic and Statistical Manual-IV (SCID-IV), Short-Form Health Status Survey (SF-36), and 24 h Feeding Paradigm. RESULTS: Twenty-five percent of subjects were classified as BED (11% met full and 14% partial BED criteria) and 75% of subjects were classified as non-BED. BED (full and partial) subjects had higher eating disturbance in terms of eating concern and shape concern (as found by the EDE), higher disinhibition (as found by the TFEQ), and they consumed more liquid meal during the 24 h feeding paradigm. No difference was found in psychiatric morbidity between BED and non-BED in terms of DSM-IV Axis I diagnosis. The health status scores of both BED and non-BED subjects were significantly lower than US norms on all subscales of the SF-36, particularly the BED group. CONCLUSION: Our findings support the validity of the category of BED within a population of extremely obese individuals before undergoing GBP. BED subjects differed from their non-BED counterparts in that they had a greater disturbance in eating attitudes and behavior, a poorer physical and mental health status, and a suggestion of impaired hunger/satiety control. However, in this population of extremely obese subjects, the stability of BED warrants further study.

Adult↗
PubMed2002

Disc morphology in health and disease.

The morphology of the intervertebral disc is dependent on the type of components present and the manner in which they are assembled. This, in turn, will determine how the tissue carries out its primary physiological functions of load bearing and allowing movement in all directions of the otherwise rigid spine. The disc starts its life in an ordered fashion, with the outer annulus fibrosus consisting of a series of regular concentric bundles of collagen fibres around the central gelatinous nucleus pulposus. With advancing age there is increased complexity of lamellae, with more bifurcations, interdigitations and irregularity in number and size of lamellar bands, probably as a result of the disc cells' synthetic response to variations in incident loads. This change in organization itself will lead to altered load bearing, hence possibly establishing a self-perpetuating cycle of disruption to disc morphology, which, once started, may be irreversible. There are also alterations to cell organization with disease and degeneration. There may be increased cell number, with clusters of cells forming by cell proliferation, or increased cell death, whether by necrosis or apoptosis, in degenerate or deformed discs such as are found in spinal deformities; for example, scoliosis. Any change in cell number is likely to alter the nutritive requirements and concentration gradients of both nutrients and metabolites. The normally avascular disc in the healthy adult can become increasingly vascularized and innervated with degeneration and disease. This may lead to an increased supply of oxygen and nutrients to the disc, but can also introduce other cells types and molecules such as cytokines and growth factors.

Animals↗
PubMed2002

The Living with Cancer Education Programme. I. Development of an Australian education and support programme for cancer patients and their family and friends.

After a diagnosis of cancer, patients and their families and friends experience a significant need for information about the illness, treatment and prognosis, as well as support. Structured education and support group-based programmes play a major role in meeting these needs. Following a needs assessment in 1985, the Anti-Cancer Council of Victoria (ACCV), Australia, initiated development of the Living With Cancer Education Programme (LWCEP), a structured 8-week group programme providing education and support for people with cancer and their families and friends. This paper provides an historical overview of the LWCEP, as well as an outline of the programme aims, structure, content and delivery. Recent developments and future directions are also discussed. These include adaptation of the programme for individuals with advanced or recurrent cancer, modification of the programme structure and revision of the evaluation methodology.

Australia↗
PubMed2002

The Living with Cancer Education Programme. II. Evaluation of an Australian education and support programme for cancer patients and their family and friends.

A diagnosis of cancer can have major adverse physical, psychosocial and economic consequences for both the individual diagnosed with cancer and their family and friends. The provision of adequate information and support to individuals affected by cancer plays a key role in facilitating better adjustment and coping. Psychoeducational group programmes are an effective way of meeting this need. This paper reports on the results of an evaluation of an Australian education and support programme for individuals with cancer and their family and friends - the Living with Cancer Education Programme (LWCEP). Data are presented based on the evaluation of 152 programmes involving 1460 participants conducted between 1994 and 2000. Participant responses related to changes in self, general coping abilities and satisfaction with the programme are reported. Results showed high satisfaction with the programme and significant improvement in coping abilities, knowledge and communication and relationships with significant others and health professionals among both groups of participants. These findings highlight several important issues for professionals involved in the psychosocial care of cancer patients and their family and friends.

Adaptation, Psychological↗
PubMed2001

Hadronic mass moments in inclusive semileptonic B meson decays.

We have measured the first and second moments of the hadronic mass-squared distribution in B-->X(c)l nu, for P(lepton)>1.5 GeV/c. We find = 0.251+/-0.066 GeV(2), <(M(2)(X)- )(2)> = 0.576+/-0.170 GeV(4), where M macro(D) is the spin-averaged D meson mass. From that first moment and the first moment of the photon energy spectrum in b-->s gamma, we find the heavy quark effective theory parameter lambda(1) (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) to be -0.24+/-0.11 GeV(2). Using these first moments and the B semileptonic width, and assuming parton-hadron duality, we obtain absolute value of V(cb) = 0.0404+/-0.0013.

Journal Article↗
PubMed2001

Immunohistochemical detection of Schwann cells in innervated and vascularized human intervertebral discs.

STUDY DESIGN: The ingrowth of nerves, blood vessels, and Schwann cells into human intervertebral discs was examined using immunohistochemistry for cell-type-specific markers. OBJECTIVES: To determine whether Schwann cells may contribute to disc innervation, and to assess the relation between disc innervation and vascularization. SUMMARY OF BACKGROUND DATA: Intervertebral disc degeneration was associated previously with ingrowth of blood vessels and nerves. Schwann cells are known to play an important role in regulating nerve growth and survival in other tissues, but they have not been examined in human pathologic intervertebral discs. METHODS: Serial sections of human intervertebral discs were immunostained for the neuronal markers (neurofilament 200, peripherin, protein gene product 9.5), for the Schwann cell marker (glial fibrillary acidic protein), and for the endothelial cell marker (CD34). RESULTS: Glial fibrillary acidic protein-immunopositive cells colocalized with nerves in degenerate discs, but were absent or rarely observed in nondegenerate, aneural discs. These also were seen in the disc matrix, independently of nerves. Much of the nerve and Schwann cell ingrowth was found in vascularized areas of disc tissue, where the lamellar structure of the anulus fibrosus was disrupted. Blood vessels were observed deeper into the discs than nerves or Schwann cells. CONCLUSIONS: The appearance of glial fibrillary acidic protein-immunopositive cells in diseased intervertebral discs was closely associated with nerve ingrowth. This novel finding suggests that Schwann cells have a role to play in regulating disc innervation and nerve function in the disc. Because blood vessels were observed furthermost into the disc, it is possible that degenerate disc vascularization occurs before innervation.

Adolescent↗
PubMed2001

The evidence for rickettsial disease arising in New Zealand.

AIM: To describe the first cases of serologically proven riskettsial disease reported in non-travelling New Zealanders. METHODS: We used clinical and laboratory based surveillance, review of clinical records and patient interviews. Information collected included demographics, presenting signs and symptoms, laboratory results, treatment and outcome. A limited seroprevalence study of rural-living friends and relatives was performed. We tested for rickettsial antibodies in the sera of possums trapped on properties close to the area of residence of the first two cases. RESULT: Serological results support the diagnosis of a rickettsial disease in nine patients. Clinical findings at presentation were nonspecific but included fever, rigors and headache. A rash was noted in four (44%). All had abnormal liver enzymes. Eight were hospitalised. No patient died but two were admitted to intensive care. CONCLUSIONS: There is strong clinical and serological evidence that Rickettsia typhi (the causative organism of murine typhus) or a Rickettsia typhi-like organism is present in the greater Auckland region. To prove it, the organism will need to be cultured or rickettsial DNA detected by molecular methods. Rickettsial infection needs to be included in the differential diagnosis of patients presenting with fever, headache and myalgia, particularly in those with rural lifestyles at least in the greater Auckland area.

Adult↗
PubMed2001

Lowering of blood glucose to nondiabetic levels in a hyperglycemic pig by allografting of fetal pig isletlike cell clusters.

BACKGROUND: Fetal pig isletlike cell clusters (ICCs) will differentiate when grafted into the thymus gland of outbred immunosuppressed nondiabetic pigs for up to 3 months. Whether these cells will survive for a similar period in a diabetic recipient and will mature with secretion of insulin to ameliorate the hyperglycemia is unknown. METHODS: Between 40,000 and 125,000 ICCs (7,000 to 11,400 ICCs/kg) were injected into the thymus gland of five juvenile pigs immunosuppressed with cyclosporine and deoxyspergualin, and the animals were subsequently made diabetic by the injection of streptozotocin. Insulin was administered subcutaneously, with one pig dying from hypoglycemia. The animal with the least number of ICCs transplanted was killed 81 days later, and the graft was analyzed histologically. Blood glucose levels and porcine C-peptide in the remaining animals were monitored for a median of 101 days. RESULTS: Histological analysis of the graft showed numerous epithelial cell clusters; the percentage of cells that contained insulin, glucagon, somatostatin, and pancreatic polypeptide were 61%, 64%, 25%, and 18%, respectively. Some cells contained more than one hormone. Porcine C-peptide was detected from 21 days after induction of diabetes but not before. In the pig receiving the most ICCs, blood glucose levels were lowered to nondiabetic levels 109 days after transplantation. Plasma C-peptide levels in response to glucagon in this pig steadily increased after grafting; peak levels were 0, 0.21, 0.45, and 0.52 ng/ml at 4, 21, 49, and 80 days after induction of diabetes compared to 0.09 ng/ml in control diabetic pigs. The secretion of C-peptide in response to oral and intravenous glucose and arginine also was greater than in untransplanted diabetic pigs, the pattern of secretion being consistent with developing fetal beta cells as the source of the C-peptide. Pancreatic insulin content was 0.1 mU/mg, 4% of that in nondiabetic pigs, and the number of beta cells per islet was 3 to 6 compared to 90 in nondiabetic controls. CONCLUSIONS: ICCs will differentiate and function for up to 111 days when transplanted into outbred immunosuppressed pigs rendered diabetic. Blood glucose levels can be lowered to nondiabetic levels when sufficient numbers of ICCs are grafted.

Animals↗