Biomedical subjects

G Oliver

Publications and source records attributed to G Oliver.

At least 19 recordsLinked to original sources

PubMed2005

The role of radiotracer imaging in Parkinson disease.

Radiotracer imaging (RTI) of the nigrostriatal dopaminergic system is a widely used but controversial biomarker in Parkinson disease (PD). Here the authors review the concepts of biomarker development and the evidence to support the use of four radiotracers as biomarkers in PD: [18F]fluorodopa PET, (+)-[11C]dihydrotetrabenazine PET, [123I]beta-CIT SPECT, and [18F]fluorodeoxyglucose PET. Biomarkers used to study disease biology and facilitate drug discovery and early human trials rely on evidence that they are measuring relevant biologic processes. The four tracers fulfill this criterion, although they do not measure the number or density of dopaminergic neurons. Biomarkers used as diagnostic tests, prognostic tools, or surrogate endpoints must not only have biologic relevance but also a strong linkage to the clinical outcome of interest. No radiotracers fulfill these criteria, and current evidence does not support the use of imaging as a diagnostic tool in clinical practice or as a surrogate endpoint in clinical trials. Mechanistic information added by RTI to clinical trials may be difficult to interpret because of uncertainty about the interaction between the interventions and the tracer.

Biomarkers↗

PubMed2004

Modulation of the mouse testis transcriptome during postnatal development and in selected models of male infertility.

The aim of this study is to develop an overview of genetic events during spermatogenesis using a novel, specifically targeted gonadal gene set. Two subtracted cDNA libraries enriched for testis specific and germ cell specific genes were constructed, characterized and sequenced. The combined libraries contain >1905 different genes, the vast majority previously uncharacterized in testis. cDNA microarray analysis of the first wave of murine spermatogenesis and of selected germ cell-deficient models was used to correlate the expression of groups of genes with the appearance of defined germ cell types, suggesting their cellular expression patterns within the testis. Real-time RT-PCR and comparison to previously known expression patterns confirmed the array-derived transcription profiles of 65 different genes, thus establishing high confidence in the profiles of the uncharacterized genes investigated in this study. A total of 1748 out of 1905 genes showed significant change during the first spermatogenic wave, demonstrating the successful targeting of the libraries to this process. These findings highlight unknown genes likely to be important in germ cell production, and demonstrate the utility of these libraries in further studies. Transcriptional analysis of well-characterized mouse models of infertility will allow us to address the causes and progression of the pathology in related human infertility phenotypes.

Animals↗

PubMed2003

Molecular mapping of genes conferring field resistance to South American Leaf Blight ( Microcyclus ulei) in rubber tree.

The South American Leaf Blight (SALB), caused by the fungus Microcyclus ulei, is the major rubber tree disease in all Central and South America. A population of 192 progeny individuals derived from a cross between a resistant clone and a susceptible cultivated clone was planted in a field trial in French Guiana in order to evaluate the resistance parameters under real infestation conditions. The resistance type (RT), the presence of stromata (ST) and the level of attack (AT) were observed 20-times on a 22-months period, and semi-quantitative evaluation of stromata was registered only once. The search for QTLs was performed using the Kruskal-Wallis test, Interval Mapping and the Composite Interval Mapping method. One major QTL located on linkage group g13 was detected on the RO 38 map, responsible for 36 to 89% of the phenotypic variance of resistance. This resistance QTL corresponds to one that had previously been detected under controlled conditions of infestation and we called it M13-1bn. Surprisingly, the effect of this QTL was larger under natural conditions of infestation than under controlled inoculation. Other minor QTLs (four on the RO38 map and one on the PB 260 map) were also detected. The type of resistance brought by M13-1bn, as well as its durability, are discussed. Applications for rubber tree breeding programs are considered.

Bacteria↗

PubMed2003

Treatment of hemorrhagic radiation proctitis with 4 percent formalin.

PURPOSE: The purpose of this study was to review our results in patients undergoing treatment with 4 percent formalin for radiation-induced injury to the rectum. METHODS: A retrospective review of office charts was performed, identifying all patients undergoing formalin treatment. Patient gender, initial malignancy, prior treatments, response to treatment with formalin, complications, and length of follow-up were reviewed. All patients had flexible endoscopy to assess for proximal sources of bleeding. The indication for treatment was a symptomatic patient with endoscopic evidence of radiation injury. A cotton pledget was used for direct application of 4 percent formalin to the affected area via a rigid proctoscope or anoscope. The treatment was repeated if blanching did not occur or if bleeding continued. Patients were followed up at three-week to four-week intervals and treatment was repeated based on the above indications. Treatments were continued until cessation of bleeding occurred or, when treatment failed, operative treatment was required. RESULTS: Thirty-six patients were identified. Three were lost to follow-up. Symptoms included bleeding in all but one patient, who presented with an ulcer. There were 33 (26 male) patients. Seventeen (51.5 percent) patients had prior treatment. The number of formalin treatments ranged from 1 to 13, with a mean of 3.4. The follow-up ranged from 1 to 60 months, with a mean of 18 months. Twenty-nine (88 percent) patients had improvement or cessation of symptoms. Four (12 percent) patients failed treatment. Two patients were noted to have full-thickness ulcers and both failed formalin treatment. No complications were noted related to formalin treatment. CONCLUSION: We conclude that formalin therapy is a safe and effective form of treatment that can be performed in the office with minimal discomfort and no complications. It can be performed multiple times until results are achieved. Formalin therapy may be useful as a first-line treatment for chronic radiation proctitis, however, a prospective controlled trial comparing modalities is required to prove this to be true.

Colonoscopy↗

PubMed2002

Assessment of beta-glucuronidase levels in goat's milk as an indicator of mastitis: comparison with other mastitis detection methods.

The use of somatic cell counts (SCCs) for the diagnosis of mastitis is not a well-established procedure for the caprine species, because nonleucocytic cell-like particles are normally observed as a result of the apocrine secretion process of the goat mammary gland. The infection levels of 124 goats were measured by the beta-glucuronidase test, which was compared with the SCC method and the California mastitis test (CMT). Seventy-nine of 124 samples (63.7%) showed SCCs lower than 1.3 x 10(3) cells per ml. Of these samples, 93% showed low levels of beta-glucuronidase activity (< 15 U/ml). In the remaining 36.3% of the samples, SCCs were higher than 1.3 x 10(3) cells per ml. Of these samples, 88% showed high levels of beta-glucuronidase activity (15 to 100 U/ml). The CMT gave similar results. In this study, the beta-glucuronidase test was standardized for goat milk and shown to be reliable, enabling one to count only the somatic enzyme cells in milk and avoiding the interference encountered with the SCC method.

Animals↗

PubMed2001

Phosphatidylinositol-specific phospholipase C activity in Lactobacillus rhamnosus with capacity to translocate.

Phosphatidylinositol-specific phospholipase C (PI-PLC) activity was investigated in 25 different lactic acid bacteria (LAB) strains belonging to the genera Lactobacillus, Weisella, and Enterococcus. PI-PLC activity was detected in 44% of the strains studied in culture medium without carbon source. From the PI-PLC positive strains, Lactobacillus rhamnosus ATCC 7469 was selected for translocation studies. Healthy mice were orally administered with a daily dose of 2.0 x 10(9) of viable L. rhamnosus suspension. Viable bacteria were detected in liver and spleen of mice fed with LAB for 7 days. Bacterial colonies isolated from liver were biochemically characterized, and further subjected to randomly amplified polymorphic DNA. Amplification patterns of five strains displayed identical profiles to L. rhamnosus. PI-PLC activity was determined in the strains recovered from liver.

Animals↗

PubMed2001

Accuracy of self-reports of acquired immunodeficiency syndrome and acquired immunodeficiency syndrome-related conditions in women.

To investigate the validity of self-reported acquired immunodeficiency syndrome (AIDS) among women enrolled in a prospective study of human immunodeficiency virus (HIV) infection, the authors compared the self-reported occurrence of AIDS-specific diagnoses with AIDS diagnoses documented by county AIDS surveillance registries. Also examined was the association between participant characteristics and the validity of self-reports. Among the 339 HIV-infected participants in the Northern California Women's Interagency HIV Study between October 1994 and September 1998, 217 reported having been given a diagnosis of AIDS. Of these 217 women, 157 (72%) were listed in the registry as having AIDS. Among the specific AIDS-related conditions reported by three or more women, the sensitivity was highest for tuberculosis (100%), CD4 cell count less than 200 (84%), Mycobacterium avium complex (73%), and Pneumocystis carinii pneumonia (69%), and the positive predictive value was highest for CD4 cell count less than 200 (75%). Among all reported AIDS diagnoses, the kappa statistic was highest for cryptococcosis (0.67) and CD4 cell count less than 200 (0.57). The only statistically significant participant characteristic associated with inaccurate reporting of an AIDS diagnosis was being a current cigarette smoker (adjusted odds ratio = 2.57, 95% confidence interval: 1.17, 5.64). Overall, self-reporting of any AIDS-related condition is fairly accurate, but there is great variability in the accuracy of specific conditions.

AIDS-Related Opportunistic Infections↗

PubMed2001

Dating of the oldest continental sediments from the Himalayan foreland basin.

A detailed knowledge of Himalayan development is important for our wider understanding of several global processes, ranging from models of plateau uplift to changes in oceanic chemistry and climate. Continental sediments 55 Myr old found in a foreland basin in Pakistan are, by more than 20 Myr, the oldest deposits thought to have been eroded from the Himalayan metamorphic mountain belt. This constraint on when erosion began has influenced models of the timing and diachrony of the India-Eurasia collision, timing and mechanisms of exhumation and uplift, as well as our general understanding of foreland basin dynamics. But the depositional age of these basin sediments was based on biostratigraphy from four intercalated marl units. Here we present dates of 257 detrital grains of white mica from this succession, using the 40Ar-39Ar method, and find that the largest concentration of ages are at 36-40 Myr. These dates are incompatible with the biostratigraphy unless the mineral ages have been reset, a possibility that we reject on the basis of a number of lines of evidence. A more detailed mapping of this formation suggests that the marl units are structurally intercalated with the continental sediments and accordingly that biostratigraphy cannot be used to date the clastic succession. The oldest continental foreland basin sediments containing metamorphic detritus eroded from the Himalaya orogeny therefore seem to be at least 15-20 Myr younger than previously believed, and models based on the older age must be re-evaluated.

Journal Article↗

PubMed2001

Effect of different complex carbon sources on growth and bacteriocin synthesis of Enterococcus faecium.

Different criteria are followed in order to select bacteria to be used in probiotic and symbiotic supplements. A new parameter to choose strains could be fermentation by intestinal bacteria of some complex carbohydrates because they are prebiotics and promote the development of beneficial microorganisms in the intestinal environment. An Enterococcus faecium strain, isolated from the crop of a free-range chicken, was assayed in order to determine the utilization of commercial sugars and/or crude carbohydrate samples from a sugar mill. The production of antimicrobial substances, under these conditions, was also considered. Ent. faecium CRL1385 grew well in the presence of complex carbohydrates and its ability to produce bacteriocin, active against poultry pathogens such as Ent. hirae, Salmonella pullorum and Listeria monocytogenes, was not significantly modified. These results are promising because the trend today is to employ eubiotic or symbiotic products and their use in the poultry industry could be a natural way to protect the flocks against potential pathogens.

Animals↗

PubMed2001

Six3 promotes the formation of ectopic optic vesicle-like structures in mouse embryos.

A few years ago, three novel murine homeobox genes closely related to the Drosophila sine oculis (so) gene (Six1-3) were isolated and were all included in the Six/so gene family. Because of its early expression in the developing eye field, Six3 was initially thought to be the functional ortholog of the Drosophila so gene. This hypothesis was further supported by the demonstration that ectopic Six3 expression in medaka fish (Oryzias latipes) promotes the formation of ectopic lens and retina tissue. Here, we show that similar to Drosophila, where the eyeless/Pax6 gene regulates the eye-specific expression of so, Six3 expression in the murine lens placodal ectoderm is also controlled by Pax6. We also show that ectopic Six3 expression promotes the formation of ectopic optic vesicle-like structures in the hindbrain-midbrain region of developing mouse embryos.

Amino Acid Sequence↗

PubMed2001

Linking specialisation to diversification in the Diplectanidae Bychowsky 1957 (Monogenea, Platyhelminthes).

The hypothesis of a positive correlation between host specificity and taxonomic diversification was tested in a family of fish ectoparasites, the Diplectanidae Bychowsky 1957 (Monogenea). A comparative analysis of correlation of species richness with host specificity was performed using an adapted independent contrasts method. In order to control for phylogenetic effects, a phylogenetic tree of the genera in the Diplectanidae was reconstructed using morphological characters. The current taxonomy is retrieved in this phylogenetic hypothesis, except for the Murraytrematoidinae subfamily, which appears to be paraphyletic. There is no significant correlation between host specificity and taxonomic diversification in the Diplectanidae. The significance of this result is discussed, and different hypotheses which could have led to this observation are presented.

Animals↗

PubMed2001

Influence of temperature on flavour compound production from citrate by Lactobacillus rhamnosus ATCC 7469.

The citrate utilization by Lactobacillus rhamnosus ATCC 7469 was found to be temperature-dependent. The maximum citrate utilization and incorporation of [1,5-14C]citrate rate were observed at 37 degreesC. At this temperature, maximum citrate lyase activity and specific diacetyl and acetoin production (Y(DA%)) were observed. The high levels of alpha-acetolactate synthase and low levels of diacetyl reductase, acetoin reductase and L-lactate dehydrogenase found at 37 degreesC led to an accumulation of diacetyl and acetoin. Optimum lactic acid production was observed at 45 degreesC, according to the high lactate dehydrogenase activity. The NADH oxidase activity increased with increasing culture temperature from 22 degreesC to 37 degreesC. Thus there are greater quantities of pyruvate available for the production of alpha-acetolactate, diacetyl and aceotin, and less diacetyl and acetoin are reduced.

Acetoin↗

PubMed2001

Chromium accumulation by two Streptomyces spp. isolated from riverine sediments.

Strains designated R22 and R25, isolated from Salí River sediments, Argentina, were highly resistant to chromium. These strains were shown by 16S rRNA sequencing studies to be Streptomyces spp.; this affiliation was consistent with morphological and chemical characteristics. Growth of strains R22 and R25 in medium containing 100 mg l(-1) chromate was reduced by only 23% and 34%, respectively, compared with growth in medium without added chromium. Streptomyces sp. strains R22 and R25 both accumulated chromium with yields of 10.0 and 5.6 mg Cr g(-1) of dry weight, respectively, and a chromate concentration of 50 mg ml(-1). Cell fractionation studies with strain R22 showed that the great majority of the chromium were associated with the cell wall fraction. Streptomyces strains R22 and R25 may have applications in bioremediation of chromium contamination.

Biodegradation, Environmental↗

PubMed2001

Hospitals and consumer health information in New Zealand: the role of the library.

A research project was conducted with the primary objective of finding out what New Zealand hospitals are doing about providing consumer health information to patients, and specifically, the role played by hospital libraries. A database was compiled of all New Zealand hospitals, both public and privately funded. An individual responsible for consumer health information was identified at each hospital and a questionnaire sent directly to them. A 64% response rate was achieved, representing 196 hospitals. Fifty-four hospitals reported having an in-house Library or Information Centre for patients, but the materials and services provided varied widely. Results from this survey show that the provision of consumer health information in the hospital sector in New Zealand is ad hoc, and libraries are not necessarily involved.

Humans↗

PubMed2001

Effect of curing conditions and Lactobacillus casei CRL705 on the hydrolysis of meat proteins.

AIMS: The effect of the common curing conditions used during the manufacture of dry fermented sausage on the proteolytic activity of Lactobacillus casei CRL705 against meat proteins was investigated. METHODS AND RESULTS: Hydrolysis of pork muscle sarcoplasmic and myofibrillar proteins was evaluated by SDS-PAGE and reverse phase-HPLC analysis. Ascorbic acid exerted a stimulatory effect on both sarcoplasmic and myofibrillar protein breakdown by Lact. casei CRL705 with the release of hydrophilic peptides and free amino acids, while NaCl and NaNO2 mainly stimulated myofibrillar degradation. CONCLUSION: Even when processing temperature (25 degrees C) did not positively affect bacterial protein hydrolysis, the presence of curing salts accounted for a remarkable increase in the non-volatile components that constitute taste-active compounds that strongly influence the final flavour of the product. SIGNIFICANCE AND IMPACT OF THE STUDY: To predict the suitability of Lact. casei CRL705 and its proteolytic enzymes as a starter culture for the dry processing of dry fermented sausages.

Amino Acids↗

PubMed2001

Enteric bifidobacteria: isolation from human infants and challenge studies in mice.

Bifidobacteria from breast-fed infants, formula-fed infants, or premature babies fed by parenteral methods were isolated and identified. The persistence of these microorganisms in the gastrointestinal tract of mice, after oral administration, was studied to determine the optimal dose and frequency of translocation to the liver and spleen. The rate of isolation among infants varied between 19 and 82% depending on the origin of the samples, with the highest values seen in breast-fed babies. The predominant species found in all cases was Bifidobacterium adolescentis. The optimal dose for oral administration of bifidobacteria to mice was 10(7) cells per day per animal for up to 2, 5, or 7 days. These bacteria remained up to 5 days postfeeding, even if feeding was interrupted. The results of bacterial translocation assays showed differences for the different strains and doses tested.

Animals↗

PubMed2001

Characterization of the lactic acid bacteria in ewe's milk and cheese from northwest Argentina.

Indigenous lactic acid bacteria in ewe's milk and artisanal cheese were studied in four samples of fresh raw milk and four 1-month-old cheeses from the provinces of northwest Argentina. Mean growth counts on M17, MRS, and MSE agar media did not show significant differences (P < 0.05) in raw milk and cheeses. Isolates of lactic acid bacteria from milk were identified as Enterococcus (48%), lactococci (14%), leuconostocs (8%), and lactobacilli (30%). All lactococci were identified as Lactococcus lactis (subsp. lactis and subsp. cremoris). Lactobacilli were identified as Lactobacillus plantarum (92%) and Lactobacillus acidophilus (8%). Enterococci (59%) and lactobacilli (41%) were isolated from cheeses. L. plantarum (93%), L. acidophilus (5%), and Lactobacillus casei (2%) were most frequently isolated. L. lactis subsp. lactis biovar diacetylactis strains were considered as fast acid producers. L. lactis subsp. cremoris strains were slow acid producers. L. plantarum and L. casei strains identified from the cheeses showed slow acid production. The majority of the lactobacilli and Lactococcus lactis strains utilized citrate and produced diacetyl and acetoin in milk. Enzyme activities (API-ZYM tests) of lactococci were low, but activities of L. plantarum strains were considerably higher. The predominance of L. plantarum in artisanal cheese is probably important in the ripening of these cheeses due to their physiological and biochemical characteristics.

Animals↗

PubMed2001

Mycoflora in commercial pet foods.

This article reports on the identification of mycoflora of 21 dry pet foods (12 belonging to dogs and 9 to cats) that corresponded to 8 commercial brands made in Argentina and imported. The isolation frequency and relative density of the prevalent fungal genera are compared too. Ten genera and fungi classified as Mycelia sterilia were identified. The predominant genera were Aspergillus (62%), Rhizopus (48%), and Mucor (38%). The most prevalent among Aspergillus was Aspergillus flavus followed by Aspergillus niger and Aspergillus terreus. The predominant Mucor was Mucor racemosus followed by Mucor plumbeus and Mucor globosus. The moisture content of these foods ranged from 5.6 to 10.0% and from 7.2 to 9.9% for dog and cat foods, respectively. A greater moisture content in food for the senior category (9.5 +/- 0.2) was observed only in comparison to adult and kitten/puppy. If the moisture content can be maintained at these levels, mold growth would be prevented or at least it would remain at an insignificant level. Some genera and species isolated and identified from the foods analyzed are potentially producing toxins, which are known as mycotoxins. This involves a risk for animal health.

Animal Feed↗