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Biomedical subjects

K Charles

Publications and source records attributed to K Charles.

16 recordsLinked to original sources
PubMed2006

Soil inactivation of DNA viruses in septic seepage.

AIMS: To generate field-relevant inactivation data for incorporation into models to predict the likelihood of viral contamination of surface waters by septic seepage. METHODS AND RESULTS: Inactivation rates were determined for PRD1 bacteriophage and Adenovirus 2 in two catchment soils under a range of temperature, moisture and biotic status regimes. Inactivation rates presented for both viruses were significantly different at different temperatures and in different soil types (alpha = 0.05). Soil moisture generally did not significantly affect virus inactivation rate. Biotic status significantly affected inactivation rates of PRD1 in the loam soil but not the clay-loam soil. Adenovirus 2 was inactivated more rapidly in the loam soil than PRD1 bacteriophage. CONCLUSIONS: Virus inactivation rates incorporated into models should be appropriate for the climate/catchment in question with particular regard to soil type and temperature. Given that PRD1 is similar in size to adenoviruses, yet more conservative with regard to inactivation in soil, it may be a useful surrogate in studies of Adenovirus fate and transport. SIGNIFICANCE AND IMPACT OF THE STUDY: A better understanding of the factors that govern virus fate and transport in catchments would facilitate the design of barrier measures to prevent viral contamination of surface waters by septic seepage.

Adenoviridae↗
PubMed2005

Disaggregation and valuation of collective dose and global circulation dose.

This study is an extension of earlier work (Jones et al 2004 J. Radiol. Prot. 24 13-27) using an adaptation of the PC-CREAM computer model (Mayall et al 1997 NRPB-SR296 (EUR 17791 EN) (Chilton: NRPB)) applied to future discharge scenarios for the nuclear fuel reprocessing plant at Sellafield, Cumbria, UK. This work showed that, of the total 3700 person-Sv collective dose delivered to the world population over 500 years integration from a particular scenario (SF3), 95% is at levels of individual dose below 0.015 microSv y(-1). The collective dose delivered at individual dose rates below 0.015 microSv y(-1) reflects the contribution from globally circulating radionuclides, namely (3)H, (14)C, (85)Kr and (129)I. The methodology used in the earlier work could not break down the dose from globally circulating radionuclides into bands of individual dose; the principal aim of this study is to achieve such a breakdown. The results confirm that the global circulation dose is received in the very lowest bands i.e. all below 0.015 microSv y(-1) for atmospheric discharges, and all below 0.0015 microSv y(-1) for discharges to the sea in the SF3 scenario. If account is taken of the argument that the monetary value of the detriment associated with collective dose should reduce with decreasing levels of individual dose or risk (Jackson et al 2004 J. Radiol. Prot. 24 41-59; NRPB 1993 Doc. NRPB 4 (2) 75-80) then it can be shown that the value of the detriment associated with discharges in the SF3 scenario would be substantially reduced compared with that derived from current conventional assumptions.

England↗
PubMed2003

MEAD (part II)-Predictions of radioactivity concentrations in the Irish Sea.

The predictions from MEAD, a model that simulates the transport of radionuclides in the marine environment, are presented for the Irish Sea. MEAD predictions for (137)Cs and Pu(alpha) are presented following discharges from BNFL Sellafield and the predictions compared to measured data from near the discharge location and further a field in the Irish Sea. The model performs well in most circumstances given the uncertainties involved in both modelling and data collection although some inconsistencies in the predictions are found. MEAD is also compared to other models of radionuclide transport in the Irish Sea.

Cesium Radioisotopes↗
PubMed2003

Buffer distances for on-site sewage systems in Sydney's drinking water catchments.

Pathogens and nutrients released from on-site sewage systems represent a risk to surface and ground water quality, particularly where there are sensitive receiving waters such as in drinking water catchments. Buffer zones between on-site systems and waterways are one barrier used to protect water quality. The increased time and distance they provide increases the opportunities for the effluent purification functions of the soil to occur. A risk management model is proposed to assess the efficacy of the buffer zones in Sydney's drinking water catchments. The model is the basis for the development of performance based setback distances for on-site systems from waterways, and incorporates stochastic analysis of pathogen and nutrient transport in the environment and consideration of the effluent quality variability from on-site systems. Catchment-scale integration of contaminant transport is employed to facilitate a risk assessment of on-site systems. The risk management model also allows for the impact of on-site system management and maintenance on catchment water quality to be assessed through scenario building and feedback mechanisms.

Models, Theoretical↗
PubMed2003

Centralised versus decentralised sewage systems: a comparison of pathogen and nutrient loads released into Sydney's drinking water catchments.

Data collected from centralised and decentralised sewage treatment plants throughout Sydney's drinking water catchments was used to calculate the relative catchment loads of Cryptosporidium, enteric viruses, nitrogen and phosphorus for an initial screening assessment. Loads were assessed at median and 90 percentile values for expected and worst-cases scenarios. The expected scenario in the Sydney drinking water catchments is that decentralised systems (servicing 32,800 people) provide similar total loads to centralised systems (serving 70% of the catchment population) for total phosphorus (37,090 kg x y(-1)), Cryptosporidium (10(11) oocysts x y(-1)) and enteric viruses (9.1 x 10(13) y(-1)), but higher loads of total nitrogen (237,610 vs. 136,740 kg x y(-1)). Decentralised systems, however, were predicted to have higher loads in the worst-case scenario with 620,620 kg x y(-1) TN, 82,040 kg x y(-1) TP, 7.3 x 10(13) Cryptosporidium oocysts x y(-1) and 9 x 10(15) enteric viruses per year. Greater load variability was experienced with decentralised systems, which presumably reflects less reliability in their current operation and maintenance. Overall, catchment water quality is therefore not only affected by sewage disposal methods, but also failure issues. Decentralised system disposal to land may afford a degree of mitigation that can be enhanced, if the degree of failure is reduced.

Animals↗
PubMed2001

Homogeneous preparations of 3'-phosphoglycolate-terminated oligodeoxynucleotides from bleomycin-treated DNA as verified by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

Single- and double-strand breaks bearing 3'-phosphoglycolate termini are among the most frequent lesions formed in DNA by ionizing radiation and other oxidative mutagens. In order to obtain homogeneous preparations of defined 3'-phosphoglycolate substrates for repair studies, 5'-(32)P-end-labeled partial duplex DNAs were treated with bleomycin, and individual cleavage products were isolated from polyacrylamide gels. The fragments were then treated with alkaline phosphatase and further purified by reverse-phase HPLC. Electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry of the purified oligomers produced molecular ions of the expected masses, with no detectable contaminants. Gas-phase sequencing by tandem mass spectrometry of these single species yielded the expected sequence ions and confirmed the presence of phosphoglycolate on the 3'-terminal fragments only. The fragments could be relabeled with polynucleotide kinase to yield highly purified, high-specific-activity substrates for repair studies.

Alkaline Phosphatase↗
PubMed2001

[Family planning among teenage mothers in a Cameroonian centre].

This study was carried out in Yaounde (Cameroon) in 1995 to determine the knowledge, attitude and behaviour of teenage mothers towards family planning. The study was based on a questionnaire administered at household level drawn from previously determined clusters. It was accomplished by recruiting 462 teenage mothers with ages ranging from 14 to 19 years and who had 1 to 3 children. On the whole, 93.9% had heard of family planning, 72.5% had heard of family planning centres, but only 43% had been to one of these centres at least once. With regards to contraceptive prevalence, 62.1% affirmed the use of a contraceptive method at the time of the study with periodic abstinence being the most widely used (35.9%). Besides the common methods, some teenage mothers made use of herbal concoctions and vaginal douching, sometimes with permanganate or the taking of tablets. Nineteen per cent of respondents had had between one and four episodes of induced abortion. According to these teenagers, the ideal average age for first delivery is 19.7 +/- 2.5 years, whereas that of nubility is 22.8 +/- 3.3 years, a difference of 3 years. This suggests that on the whole, teenage mothers believe that first delivery must precede marriage.

Abortion, Induced↗
PubMed2000

Meckel's diverticulum.

Although Meckel's diverticulum is the most prevalent congenital abnormality of the gastrointestinal tract, it is often difficult to diagnose. It may remain completely asymptomatic, or it may mimic such disorders as Crohn's disease, appendicitis and peptic ulcer disease. Ectopic tissue, found in approximately 50 percent of cases, consists of gastric tissue in 60 to 85 percent of cases and pancreatic tissue in 5 to 16 percent. The diagnosis of Meckel's diverticulum should be considered in patients with unexplained abdominal pain, nausea and vomiting, or intestinal bleeding. Major complications include bleeding, obstruction, intussusception, diverticulitis and perforation. The most useful method of diagnosis is with a technetium-99m pertechnetate scan, which is dependent on uptake of the isotope in heterotopic tissue. Management is by surgical resection.

Female↗
PubMed1998

Action of bleomycin on structural mimics of intermediates in DNA double-strand cleavage.

Bleomycin-induced cleavage was examined in several nicked, gapped, or intact duplex DNA substrates, including a structure designed to mimic a proposed singly nicked intermediate in double-strand cleavage. This nicked structure appeared to correctly target the second cleavage event in the complementary strand, resulting in a blunt-ended double-strand break, similar to that induced directly by bleomycin alone in an intact duplex of the same sequence. A one-base-gapped structure was markedly less efficient in correctly targeting bleomycin attack in the complementary strand. The results are consistent with a model of bleomycin-induced double-strand cleavage in which the nick formed by the initial bleomycin attack serves to target secondary attack to a specific position in the complementary strand, resulting in a double-strand break with a defined geometry.

Antibiotics, Antineoplastic↗
PubMed1998

A prospective study of serum pancreatic elastase-1 in the diagnosis and assessment of acute pancreatitis.

BACKGROUND: Serum amylase gives a poor estimate of both the true incidence and the severity of acute pancreatitis (AP). METHODS: We evaluated serum pancreatic elastase-1 (PE-1) prospectively in 567 patients in whom AP was suspected. In established AP, severity was assessed using the Glasgow Criteria, and C-reactive protein, amylase, and serum PE-1 were evaluated over 5 days. RESULTS: The sensitivity, specificity, and diagnostic efficiency of serum PE-1 were 0.66, 0.85, and 0.84, respectively. The diagnostic accuracy of serum PE-1 was 0.80, and that of amylase 0.97. Serum PE-1 did not correlate with disease severity or the development of complications, but it fell more slowly than the serum amylase in the week after admission. CONCLUSIONS: The serum PE-1 level correlated closely with the serum amylase but conferred no benefit as a diagnostic test, nor did it provide further prognostic information.

Acute Disease↗
PubMed1998

Monofunctional adenine N-3 adducts of melphalan: occurrence at a mutational hotspot sequence and resistance to removal by AlkA protein.

Previous work showed that a CTAAA sequence in the supF gene of the shuttle plasmid pZ189 was a hotspot for mutagenesis by the aromatic nitrogen mustards melphalan and chlorambucil, and indirect evidence suggested adenine N-3 adducts as premutagenic lesions. In order to characterize the adducts formed at this sequence more directly, a substrate was prepared in which the three adjacent adenines in the CTAAA sequence were 3H-labeled. Following treatment of this substrate with [14C]melphalan, thermolabile adducts were depurinated and analyzed by HPLC. Only a single peak bearing both 3H and 14C label was detected and it coeluted with the single major adduct formed by the reaction of melphalan with free adenine base. Various spectrometric analyses of this species were all consistent with its identification as a monofunctional adenine N-3 adduct of melphalan. There was no evidence for any bifunctional adducts involving the labeled adenines. There was little if any release of the adenine N-3 adduct of melphalan by Escherichia coli AlkA protein, under conditions where 3-methyladenine was quantitatively released. The results support the proposal that monofunctional adenine N-3 adducts are intermediates in the generation of A.T-->T.A and A.T-->C.G transversions by aromatic nitrogen mustards.

Base Sequence↗
PubMed1997

A patient with unique bilateral ovarian metastases 11 years after the treatment of breast cancer.

We report a patient in whom 11 years after the treatment of a breast tumour, bilateral ovarian metastases were disclosed. Surgical exploration confirmed unique ovarian metastases within a 'clean' abdomen and pelvis. The particularities of this case compared with the literature are the rather long interval of 11 years and the fact that no other metastases were present. The literature indeed reveals that most of the patient with ovarian metastases are premenopausal, have bilateral involvement; the ovarian metastases occur within a few years and are frequently accompanied by other metastases.

Breast Neoplasms↗
PubMed1996

Palliative care providers' perspectives on service and education needs.

To obtain the information necessary for coordinated regional program development, we examined (a) the multidisciplinary viewpoint of palliative care service provision and (b) the continuing education needs reported by non-physician service providers. Of 146 surveys distributed to care providers from multiple settings, 135 were returned. Respondents cited these problems: fragmented services, poor pain and symptom control, lack of education for providers, lack of public awareness, problems with the continuity and coordination of care, lack of respite, and lack of hospice beds. Stress management for caregivers, pain management, communication skills, and symptom assessment were rated as priorities in continuing education. Lectures, small group discussions, practicum, and regular medical centre rounds were the preferred learning formats, while costs and staff shortages were cited as educational barriers.

Data Collection↗
PubMedDate not supplied

Storage and microencapsulation of islets for transplantation.

Microencapsulation is an effective means of immunoisolation for pancreatic islet transplants. However, the process of isolating, purifying, encapsulating, and transplanting islets in a single day is labor intensive and difficult for routine use. There is an apparent need for reliable methods of islet storage, and cryopreservation has emerged as an attractive system of islet banking. While studies have shown that cryopreserved islets are viable when tested unencapsulated after thawing, it is not clear if the combination of freezing and encapsulation would affect islet function. The purpose of the present study was to determine the in vitro function of cryopreserved islets following thawing and microencapsulation. Islets were isolated from the pancreata of Sprague-Dawley rats and cryopreserved under liquid nitrogen for either 1 week or 1 month, following an overnight culture at 37 degrees C. Upon thawing, the islets were tested either unencapsulated or after encapsulation in polylysine-alginate membrane. In all experiments islets were preperifused for 1 h at 37 degrees C with a modified Krebs-Ringer bicarbonate buffer containing 3.3 mM (60 mg/dl) glucose and maintained at pH 7.4 by continuous gassing with 95% air/5% CO2. Following basal effluent sample collection on ice, the glucose concentration was raised to 16.7 mM (300 mg/dl). It was found that, within 10 min of high glucose stimulation, an average of twofold increase in insulin secretion (p < 0.01) was obtained in islets within or without microcapsules. We conclude that islets cryopreserved for 1 month prior to thawing and microencapsulation retained functional viability as determined in in vitro experiments.

Animals↗
PubMedDate not supplied

Reported changes in the sexual behavior of men at risk for AIDS, San Francisco, 1982-84--the AIDS Behavioral Research Project.

We surveyed 454 men in November 1983 and in May 1984 regarding their sexual practices during the month before the survey. In the 1983 survey, we also asked for reports about sexual behavior during the same month 1 year prior to the survey. The sample consisted of men recruited as they left bath-houses and bars, men who had not used bars or baths for meeting sexual partners for 2 months prior to the November 1983 survey, and men in committed primary relationships with another man. We found substantial changes in reported sexual behavior with persons other than a primary partner. The average number of male partners declined from 6.3 in November 1982 to 3.9 in May 1984. Receptive anal intercourse without condom declined from 1.9 to 0.7, oral-anal contact declined from 1.1 to 0.3, and swallowing semen declined from 2.8 to 0.7 in terms of the number of times that the respondent engaged in the act in the last month. These same changes did not occur in relation to sex with a primary partner. Only one variable, namely, increased length of time since the first homosexual experience, distinguished persons maintaining few sexual partners from those increasing the number of sexual partners from November 1983 to May 1984. Four variables distinguished those retaining high numbers of sexual partners from those lowering the number of sexual partners, namely, ability to remember a visual image of AIDS deterioration, age, relationship status, and length of time since first homosexual experience.

Acquired Immunodeficiency Syndrome↗