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Biomedical subjects

R H Williams

Publications and source records attributed to R H Williams.

At least 19 recordsLinked to original sources
PubMed2006

The prevalence of Neospora caninum and co-infection with Toxoplasma gondii by PCR analysis in naturally occurring mammal populations.

Neospora caninum and Toxoplasma gondii are closely related intracellular protozoan parasites associated with bovine and ovine abortion respectively. Little is known about the extent of Neospora/Toxoplasma co-infection in naturally infected populations of animals. Using nested PCR techniques, based on primers from the Nc5 region of N. caninum and SAG1 for T. gondii, the prevalence of N. caninum and its co-infection with T. gondii were investigated in populations of Mus domesticus, Rattus norvegicus and aborted lambs (Ovis aries). A low frequency of infection with N. caninum was detected in the Mus domesticus (3%) and Rattus norvegicus (4.4%) populations. A relatively high frequency of infection with N. caninum was detected in the brains of aborted lambs (18.9%). There was no significant relationship between N. caninum and T. gondii co-infection. Investigation of the tissue distribution of Neospora, in aborted lambs, showed that Neospora could not be detected in tissues other than brain and this was in contrast to Toxoplasma where the parasite could be frequently detected in a range of tissues.

Abortion, Veterinary↗
PubMed2005

High levels of congenital transmission of Toxoplasma gondii in longitudinal and cross-sectional studies on sheep farms provides evidence of vertical transmission in ovine hosts.

Recent research suggests that vertical transmission may play an important role in sustaining Toxoplasma gondii infection in some species. We report here that congenital transmission occurs at consistently high levels in pedigree Charollais and outbred sheep flocks sampled over a 3-year period. Overall rates of transmission per pregnancy determined by PCR based diagnosis, were consistent over time in a commercial sheep flock (69%) and in sympatric (60%) and allopatric (41%) populations of Charollais sheep. The result of this was that 53.7 % of lambs were acquiring an infection prior to birth: 46.4% of live lambs and 90.0% of dead lambs (in agreement with the association made between T. gondii and abortion). No significant differences were observed between lamb sexes. Although we cannot distinguish between congenital transmission occurring due to primary infection at pregnancy or reactivation of chronic infection during pregnancy, our observations of consistently high levels of congenital transmission over successive lambings favour the latter.

Abortion, Veterinary↗
PubMed2005

Significant familial differences in the frequency of abortion and Toxoplasma gondii infection within a flock of Charollais sheep.

A study was carried out to investigate the frequencies of abortion and congenital Toxoplasma gondii infection within 27 families (765 individuals) of a pedigree Charollais sheep flock maintained on a working farm in Worcestershire, UK, since 1992. Pedigree lambing records were analysed to establish the frequency of abortion for each family. The frequency of congenital infection was determined for each family by PCR analysis of tissue samples taken from newborn lambs. A total of 155 lambs were tested for congenital T. gondii infection, which were all born during the study period 2000-2003. Significant differences in the frequency of abortion between sheep families within this flock were observed with frequencies ranging between 0% and 48% (P < 0.01). Significantly different infection frequencies with T. gondii were also observed for different families and ranged between 0% and 100% (P<0.01). Although the actual cause of each abortion was not verified, a highly significant positive correlation was found to exist between the frequency of abortion and the frequency of T. gondii infection in the same families (P<0.01). The data presented here raise further questions regarding the significance of congenital transmission of T. gondii within sheep populations, the possible successive vertical transmission of T. gondii within families of sheep, and the potential role of inherited genetic susceptibility to abortion with respect to T. gondii infection. This work invites further study into the epidemiology of ovine toxoplasmosis and may have implications for sheep husbandry methods in the future.

Abortion, Veterinary↗
PubMed2004

Detection of high levels of congenital transmission of Toxoplasma gondii in natural urban populations of Mus domesticus.

The relative importance of different transmission routes of Toxoplasma gondii has been a matter for debate. This ubiquitous parasite is generally thought to be transmitted by infective oocysts excreted by the definitive host, the cat. Ingestion of undercooked meat has also been considered an important route of transmission in many mammals while congenital transmission has generally been considered relatively rare. Experimental studies demonstrate the ability of T. gondii to be transmitted congenitally, but few studies have investigated the frequency of this transmission route in natural populations. We use PCR amplification of the SAG1 gene to investigate the frequency of congenital transmission in a wild population of mice (Mus domesticus) and show that congenital transmission is occurring in 75% of pregnancies in this population. Furthermore, for infected pregnant mice, transmission occurs to at least one foetus in 100% of cases while variable penetrance of congenital infection is observed. These high levels of congenital transmission in this wild population of mice, taken together with other recent data on congenital transmission in sheep, suggests that this phenomenon might be more widespread than previously thought.

Animals↗
PubMed2001

Methods for integrated air sampling and dna analysis for detection of airborne fungal spores.

Integrated air sampling and PCR-based methods for detecting airborne fungal spores, using Penicillium roqueforti as a model fungus, are described. P. roqueforti spores were collected directly into Eppendorf tubes using a miniature cyclone-type air sampler. They were then suspended in 0.1% Nonidet P-40, and counted using microscopy. Serial dilutions of the spores were made. Three methods were used to produce DNA for PCR tests: adding untreated spores to PCRs, disrupting spores (fracturing of spore walls to release the contents) using Ballotini beads, and disrupting spores followed by DNA purification. Three P. roqueforti-specific assays were tested: single-step PCR, nested PCR, and PCR followed by Southern blotting and probing. Disrupting the spores was found to be essential for achieving maximum sensitivity of the assay. Adding untreated spores to the PCR did allow the detection of P. roqueforti, but this was never achieved when fewer than 1,000 spores were added to the PCR. By disrupting the spores, with or without subsequent DNA purification, it was possible to detect DNA from a single spore. When known quantities of P. roqueforti spores were added to air samples consisting of high concentrations of unidentified fungal spores, pollen, and dust, detection sensitivity was reduced. P. roqueforti DNA could not be detected using untreated or disrupted spore suspensions added to the PCRs. However, using purified DNA, it was possible to detect 10 P. roqueforti spores in a background of 4,500 other spores. For all DNA extraction methods, nested PCR was more sensitive than single-step PCR or PCR followed by Southern blotting.

Air Microbiology↗
PubMed2001

Energy for the new millennium.

The evolution of thinking about energy is discussed. When the authors began collaborating 20 years ago, energy was typically considered from a growth-oriented, supply-side perspective, with a focus on consumption trends and how to expand supplies to meet rising demand. They were deeply troubled by the environmental, security and equity implications of that approach. For instance, about two billion people lack access to affordable modern energy, seriously limiting their opportunities for a better life. And energy is a significant contributor to environmental problems, including indoor air pollution, urban air pollution, acidification, and global warming. The authors saw the need to evolve a different perspective in which energy is provided in ways that help solve such serious problems. They argued that energy must become an instrument for advancing sustainable development--economically viable, need-oriented, self-reliant and environmentally sound development--and that the focus should be on the end uses of energy and the services that energy provides. Energy technological options that can help meet sustainable development goals are discussed. The necessity of developing and employing innovative technological solutions is stressed. The possibilities of technological leap-frogging that could enable developing countries to avoid repeating the mistakes of the industrialized countries is illustrated with a discussion of ethanol in Brazil. The role foreign direct investment might play in bringing advanced technologies to developing countries is highlighted. Near- and long-term strategies for rural energy are discussed. Finally, policy issues are considered for evolving the energy system so that it will be consistent with and supportive of sustainable development.

Brazil↗
PubMed2001

Novel approach for the determination of the redox status of homocysteine and other aminothiols in plasma from healthy subjects and patients with ischemic stroke.

BACKGROUND: Plasma "redox" status can be assessed by measurements of reduced (r)-, free (f)-, oxidized (ox)-, and protein-bound (b)-homocysteine (Hcy) plus the related aminothiols cysteine, cysteinylglycine (CysGly), and glutathione (GSH), but sample collection has been complex. The redox status has not been determined in ischemic stroke patients and may provide increased understanding of its role in pathogenesis. We wished to examine the feasibility of this measurement in samples collected in readily available acidic sodium citrate. METHODS: We measured aminothiols and their stability in stabilized protein-free filtrate using acidic sodium citrate (BioPool Stabilyte, pH 4.3) vs EDTA whole blood. Before analysis, plasma samples were also ultrafiltered to obtain a protein-free filtrate. The concentrations of total Hcy (tHcy), fHcy, and rHcy and their related aminothiols, cysteine, cysteinylglycine, and glutathione were simultaneously determined on acidic sodium-citrated blood using reversed-phase HPLC with fluorescence detection. Bound and oxidized aminothiols were calculated by difference using the concentrations of the total, free, and reduced fractions. Using this approach, we compared the redox status in newly diagnosed ischemic stroke patients (n = 20) and healthy age- and sex-matched subjects (n = 20). RESULTS: tHcy, tCys, tCysGly, and tGSH concentrations in whole blood with Stabilyte were stable for 8 h; the reduced fraction of each aminothiol was stable for 4 h. Recovery in the protein-free filtrate was 90-100% for all reduced thiols in acidified sodium-citrated blood. Patients with ischemic stroke had higher plasma tHcy, fHcy, bHcy, rHcy, and oxHcy (P <0.0005) and higher plasma t-, f-, r-, and oxCys (P <0.05). t-, b-, and rCysGly concentrations were lower in the stroke patients (P <0.05), as were t-, b-, and oxGSH (P <0.005). CONCLUSIONS: Collection of blood in acidic sodium citrate (BioPool Stabilyte) permits the determination of the redox status of Hcy and its related aminothiols, which may add to the understanding of their relationship to the etiology of cerebrovascular disease.

Adult↗
PubMed2000

Fenretinide therapy in prostate cancer: effects on tissue and serum retinoid concentration.

PURPOSE: To examine the feasibility of using fenretinide (4-HPR) for the prevention and treatment of prostate cancer. MATERIALS AND METHODS: We measured the impact of 4-HPR therapy on retinoid concentrations in vivo, in a mouse model of prostate cancer and clinically, in patients with prostate cancer who were given oral 4-HPR (200 mg/d) or placebo for 4 weeks before undergoing a radical prostatectomy. RESULTS: Prostate tumors in mice treated with 4-HPR contained high levels of 4-HPR and of all-trans-retinoic acid (RA) and reduced levels of retinol (ROH). Patients given 4-HPR were found to have significantly higher concentrations of 4-HPR in the cancerous prostate as compared with the serum levels (463 nmol/L v 326 nmol/L; P =.049), but they were only 1/10 the levels found in mice and were far below the concentrations reported in human breast tissue. Serum and tissue ROH levels were reduced to less than half the concentrations found in untreated controls. RA concentrations in human serum and in cancerous prostates were not significantly affected by 4-HPR treatment, in contrast with the findings in mice. CONCLUSION: The standard oral dose of 4-HPR proposed for breast cancer (200 mg/d) achieved only modest drug levels in the prostate and is unlikely to be effective for prostate cancer prevention or treatment. Higher doses need to be explored.

Aged↗
PubMed2000

Identification and cloning of an aspartyl proteinase from Coccidioides immitis.

A 45 kDa protein was isolated from a soluble vaccine prepared from formaldehyde-killed spherules of Coccidioides immitis. From the N-terminal amino acid sequence, the protein yielded a 17-amino-acid peptide that was homologous to sequences of other fungal aspartyl proteinases. The coccidioidal cDNA encoding the proteinase was amplified using oligonucleotide primers designed from the 45 kDa N-terminal amino acid sequence and a fungal aspartyl proteinase consensus amino acid sequence. The PCR product was cloned and sequenced, and the remaining 5' upstream and 3' downstream cDNA was amplified, cloned, and sequenced. The cDNA encoding the coccidioidal aspartyl proteinase open reading frame was cloned and the fusion protein containing a C-terminal His-tag expressed in E. coli. The recombinant aspartyl proteinase was purified by immobilized metal affinity chromatography. This recombinant protein will be used for further studies to evaluate its antigenicity, including protective immunogenicity.

Amino Acid Sequence↗
PubMed2000

Microsurgical testis biopsy: a novel technique for retrieval of testicular tissue.

PURPOSE: In vitro fertilization with intracytoplasmic sperm injection has resulted in a dramatic increase in the need for diagnostic and therapeutic testis biopsies. We developed a microsurgical testis biopsy technique which allows identification of testicular vessels and individual seminiferous tubules. We compare the results of this technique to our prior series of nonmicroscopic biopsies. MATERIALS AND METHODS: A retrospective study of 226 consecutive patients who had undergone open testes biopsy with or without an operating microscope was performed. Between 1988 and 1994 standard open testis biopsy was performed without a microscope in 119 patients and a single sample of testicular tissue was taken. After 1994 microsurgical biopsy was performed under 6 to 25x magnification in 107 patients, nearly half of whom had multiple biopsies of each testis. The complication rates of the 2 procedures were compared. RESULTS: Scrotal hematoma required surgical drainage in 3 of the 119 standard testis biopsy cases and testis atrophy was noted in 1, for a total complication rate of 3.4%. There were no episodes of clinically detectable testicular atrophy or scrotal hematoma requiring surgical drainage in the 107 microsurgical biopsy cases (p<0.05). In 2 men the microscope allowed identification of larger tubules that contained sperm. CONCLUSIONS: Use of the operating microscope for testicular biopsy allows identification and avoidance of testicular vessels, minimizing complications. It also may allow selection of seminiferous tubules more likely to contain sperm.

Biopsy↗
PubMed2000

Cocaine and its major metabolites in plasma and urine samples from patients in an urban emergency medicine setting.

In this retrospective study, we examined the levels of cocaine and its major metabolites in plasma and urine from 29 randomly selected emergency department patients (19 males and 10 females, aged 19 to 55) whose urine screened positive for benzoylecgonine using fluorescence polarization immunoassay. Levels of cocaine along with benzoylecgonine, ecgonine methyl ester, and norcocaine were quantitated in EDTA plasma and urine from each patient using gas chromatography-mass spectrometry with selected ion monitoring. Admission diagnosis and history were also obtained for each patient. In plasma, the levels were 16-130 ng/mL for cocaine (n = 3), 27-96 ng/mL for ecgonine methyl ester (n = 9), and 18-1390 ng/mL for benzoylecgonine (n = 22). Norcocaine was not detected in any of the plasma samples. In urine, the concentration ranges were 4-40,130 ng/mL for cocaine (n = 23), 36-660,500 ng/mL for ecgonine methyl ester (n = 27), and 9-2520 ng/mL for norcocaine (n = 9). All urine samples were positive for benzoylecgonine (106-3,361,000 ng/mL), and benzoylecgonine was the only metabolite present in two urine samples (at concentrations of 407 and 435 ng/mL). Two patients had plasma and urine samples positive for all analytes (except norcocaine in plasma). The patient with the highest urinary concentrations of cocaine (40,130 ng/mL), ecgonine methyl ester (660,500 ng/mL), benzoylecgonine (3,361,000 ng/mL), and norcocaine (2520 ng/mL) had a small quantity of benzoylecgonine (465 ng/mL) in plasma. No correlation was noted with patient history, admitting diagnosis or symptomatology, or plasma/urine levels of cocaine or any of its metabolites.

Adult↗
PubMed2000

Simultaneous detection and quantitation of diethylene glycol, ethylene glycol, and the toxic alcohols in serum using capillary column gas chromatography.

Determination of toxic glycols and alcohols in an emergency setting requires a rapid yet accurate and reliable method. To simultaneously determine diethylene glycol (DEG) along with ethylene glycol, methanol, isopropanol, acetone, and ethanol, we modified a previously developed gas chromatographic (GC) method. The system used a Hewlett-Packard 6890 GC with EPC, a Gooseneck splitless liner, and an Rtx-200 capillary column (30 m x 0.53-mm i.d., 3 mm). After serum samples were deproteinized using ultrafiltration (Millipore Ultrafree-MC), 1 mL of the protein-free filtrate was manually injected into the GC. Internal standards for alcohols (and acetone) and glycols were n-propanol and 1,3-butanediol, respectively. All compounds eluted within 3.5 min (linear temperature gradient from 40 to 260 degrees C); total run time was 6.5 min. Limit of detection and linear range for all compounds were 1 or 2.5 mg/dL and 0-500 mg/dL, respectively. In addition, there was no interference from propionic acid, propylene glycol, and 2,3-butanediol. The modifications in the equipment and temperature program allowed increased resolution and thus, detection and reliable quantitation of DEG and other common toxic glycols and alcohols of clinical interest.

2-Propanol↗
PubMed1998

Merkel cell carcinoma in a renal transplant patient: increased incidence?

The identification of malignancies associated with transplantation has led to enhanced vigilance and care in these patients, as well as insight into the pathogenesis of select malignancies. We report a case of Merkel cell carcinoma, an uncommon cutaneous malignancy of neuroendocrine origin, diagnosed in a 65-year-old Caucasian man 6 years after renal transplantation. While it is well known that transplant patients are at increased risk for squamous cell carcinomas of the skin, other types may also have an increased frequency. We suggest that Merkel cell carcinoma could have an increased incidence in the transplant population.

Aged↗
PubMed1998

Aggressive approach in the treatment of acute lead encephalopathy with an extraordinarily high concentration of lead.

OBJECTIVE: To report a case of a 3-year-old child with an extraordinarily massive lead concentration, 26.4 micromol/L (550 microg/dL), following environmental exposure to lead paint in the home. LITERATURE REVIEW: The relevant literature concerning the treatment of lead encephalopathy was reviewed during the treatment of this child and preparation of the manuscript. To our knowledge, the landmark article written by Julian Chisolm in 1968 is the only recent article that reported similarly high levels of lead concentration. This case, however, is the first in which 3 chelating agents were used for the treatment of lead encephalopathy. We also reviewed the literature on the use of whole bowel irrigation in heavy metal intoxications. CONCLUSIONS: In this case, aggressive gut decontamination with whole bowel irrigation and triple chelation therapy with British anti-Lewisite, EDTA, and oral succimer was well tolerated and seemed effective for rapidly deleading the child. The extent to which her lead concentration increased while being treated with oral succimer alone necessitated further chelation with EDTA. Further evaluation is necessary to determine if triple chelation therapy is an appropriate method for severe lead intoxication, and if the use of whole bowel irrigation should be considered in heavy metal intoxication.

Brain Diseases↗
PubMed1996

Human cytomegalovirus is not implicated in benign prostatic hyperplasia: a study using immunohistochemistry and the polymerase chain reaction.

PURPOSE: To evaluate whether human cytomegalovirus (CMV) may play a role in the pathogenesis of benign prostatic hyperplasia. MATERIALS AND METHODS: We used immunohistochemistry and the polymerase chain reaction (PCR) to evaluate the presence of CMV in normal prostatic tissue (n = 12) and BPH tissue (n = 21). RESULTS: Immunostaining for CMV in prostatic tissue was negative; however, staining was evident in mononuclear cells seen in the tissues of both groups. With nested PCR, CMV genomic material was demonstrated in 1 tissue specimen from each group (p > 0.1). CONCLUSIONS: These data suggest that CMV is unlikely to be a significant factor in the pathogenesis of BPH.

Base Sequence↗
PubMed1996

Pitfalls in interpreting prostate specific antigen velocity.

PURPOSE: The concept of prostate specific antigen (PSA) velocity as an improved marker for prostate cancer detection is intriguing. However, before this concept is applied to individual patients several confounding parameters must be addressed. We determined the variability of serum PSA levels in men without prostate cancer. MATERIALS AND METHODS: We reviewed data from a prostate cancer screening program, and determined inter-assay and individual variability of the serum PSA values for a 2-year followup period in 265 men clinically free of prostate cancer. RESULTS: Our average inter-assay coefficient of variation was 7.5%. Therefore, we considered only PSA changes exceeding +/- 15% as significant. Fluctuations in serum PSA occurred in 78% of the men during the observation period, and 12.5% had at least a single PSA increase exceeding 0.75 ng/ml. per year. Fluctuations were noted throughout the entire range of serum PSA levels but became progressively larger with an increasing mean PSA. CONCLUSIONS: The inter-assay variability must be considered when interpreting PSA velocity. Individual fluctuations in serum PSA dictate an observation period of at least 2 years before PSA velocity is considered abnormal.

Adult↗