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PubMed2006

Modified Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a screening test for dementia for Thai elderly.

A potential test for early detection of dementia in the elderly is the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), which is based on information from the informant for the elderly about the changes of the elderly in everyday cognitive functioning associated with dementia. The present study aimed to modify and assess the reliability and validity of the modified IQCODE consisting of 32 items. The study consisted of two methods of assessing dementia: DSMIV diagnosis carried out by clinicians, and informants responding to the IQCODE. The subjects were 200 pairs of elderly subjects and their informants who visited the Geriatric Clinic, Ramathibodi Hospital. The optimal cutoff score on the modified IQCODE was 3.42, with 90% sensitivity and 95% specificity. The positive predictive values, negative predictive values, and accuracy were 0.94, 0.90, and 0.92, respectively. The IQCODE items had high internal consistency. The IQCODE associated with the elderly person's age, but not with their gender and educational level; nor were they associated with the demographic characteristics of the informant. Therefore, the IQCODE could be used as an alternative screening test for dementia in Thailand with acceptable sensitivity and specificity. This tool may be useful for dementia screening in the community and the geriatric clinic for early detection of disease.

Adult↗
PubMed2005

Necrotizing fasciitis caused by community-associated methicillin-resistant Staphylococcus aureus in Los Angeles.

BACKGROUND: Necrotizing fasciitis is a life-threatening infection requiring urgent surgical and medical therapy. Staphylococcus aureus has been a very uncommon cause of necrotizing fasciitis, but we have recently noted an alarming number of these infections caused by community-associated methicillin-resistant S. aureus (MRSA). METHODS: We reviewed the records of 843 patients whose wound cultures grew MRSA at our center from January 15, 2003, to April 15, 2004. Among this cohort, 14 were identified as patients presenting from the community with clinical and intraoperative findings of necrotizing fasciitis, necrotizing myositis, or both. RESULTS: The median age of the patients was 46 years (range, 28 to 68), and 71 percent were men. Coexisting conditions or risk factors included current or past injection-drug use (43 percent); previous MRSA infection, diabetes, and chronic hepatitis C (21 percent each); and cancer and human immunodeficiency virus infection or the acquired immunodeficiency syndrome (7 percent each). Four patients (29 percent) had no serious coexisting conditions or risk factors. All patients received combined medical and surgical therapy, and none died, but they had serious complications, including the need for reconstructive surgery and prolonged stay in the intensive care unit. Wound cultures were monomicrobial for MRSA in 86 percent, and 40 percent of patients (4 of 10) for whom blood cultures were obtained had positive results. All MRSA isolates were susceptible in vitro to clindamycin, trimethoprim-sulfamethoxazole, and rifampin. All recovered isolates belonged to the same genotype (multilocus sequence type ST8, pulsed-field type USA300, and staphylococcal cassette chromosome mec type IV [SCCmecIV]) and carried the Panton-Valentine leukocidin (pvl), lukD, and lukE genes, but no other toxin genes were detected. CONCLUSIONS: Necrotizing fasciitis caused by community-associated MRSA is an emerging clinical entity. In areas in which community-associated MRSA infection is endemic, empirical treatment of suspected necrotizing fasciitis should include antibiotics predictably active against this pathogen.

Adult↗
PubMed2003

Immunodiagnostic tools for human and porcine cysticercosis.

The development of improved immunodiagnostic tools has contributed to our knowledge on the importance of taeniosis/cysticercosis by enabling sero-epidemiological surveys and community-based studies to be carried out. Immunodiagnostic techniques include detection methods for specific antibodies and for circulating parasite antigen in serum or cerebrospinal fluid. The antigens used in immunoblot and enzyme-linked immunosorbent assay (ELISA) for antibody detection have evolved from crude extracts to highly purified specific fractions and recombinant antigens of the glycoprotein family, increasing both the sensitivity and the specificity of the tests. The application of ELISA for the detection of circulating parasite antigens may present some diagnostic advantages since it demonstrates not only exposure but also active infections. Until now only a few of the current techniques have been standardised and fully validated, making comparisons between studies difficult. The lack of a gold standard is a serious drawback. In surveys on cysticercosis, antibody detection systems have been useful in identifying the risk factors associated with transmission of Taenia solium; a high seroprevalence in a community indicates a "hot spot" where preventive and control measures should be applied. In contrast, the potential use of immunodiagnostic tools to identify cases of neurocysticercosis (NCC) in man is subject to debate. The correlation between a positive serology and neurological symptoms and/or lesions indicative for NCC on neuro-imaging techniques is poor to fair in most studies. This may be explained by the unpredictable clinical outcome of the infection and the variable immunological response of the human host to infection. A major problem is that in many developing countries, neuro-imaging methods are inaccessible and/or too expensive for the rural population at risk. Under these conditions, serology may provide the only tool for diagnosis of the infection.

Animals↗
PubMed1999

Molecular analysis of microbial community structures in pristine and contaminated aquifers: field and laboratory microcosm experiments.

This study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (FC) or aerobic and noncontaminated (NC) and (ii) examine alterations in microbial community structures resulting from exposure to toluene and/or electron acceptor supplementation (nitrate). The latter objective was addressed by using the NC and FC aquifer materials for anaerobic microcosm studies in which phylogenetic probe analysis was complemented by microbial activity assays. Domain probe analysis of the aquifer samples showed that the communities were predominantly Bacteria; Eucarya and Archaea were not detectable. At the phylum and subclass levels, the FC and NC aquifer material had similar relative abundance distributions of 43 to 65% beta- and gamma-Proteobacteria (B+G), 31 to 35% alpha-Proteobacteria (ALF), 15 to 18% sulfate-reducing bacteria, and 5 to 10% high G+C gram positive bacteria. Compared to that of the NC region, the community structure of the FC material differed mainly in an increased abundance of B+G relative to that of ALF. The microcosm communities were like those of the field samples in that they were predominantly Bacteria (83 to 101%) and lacked detectable Archaea but differed in that a small fraction (2 to 8%) of Eucarya was detected regardless of the treatment applied. The latter result was hypothesized to reflect enrichment of anaerobic protozoa. Addition of nitrate and/or toluene stimulated microbial activity in the microcosms, but only supplementation of toluene alone significantly altered community structures. For the NC material, the dominant subclass shifted from B+G to ALF, while in the FC microcosms 55 to 65% of the Bacteria community was no longer identifiable by the phylum or subclass probes used. The latter result suggested that toluene exposure fostered the proliferation of phylotype(s) that were otherwise minor constituents of the FC aquifer community. These studies demonstrated that alterations in aquifer microbial communities resulting from specific anthropogenic perturbances can be inferred from microcosm studies integrating chemical and phylogenetic probe analysis and in the case of hydrocarbon contamination may facilitate the identification of organisms important for in situ biodegradation processes. Further work integrating and coordinating microcosm and field experiments is needed to explore how differences in scale, substrate complexity, and other hydrogeological conditions may affect patterns observed in these systems.

Bacteria, Anaerobic↗
PubMed2006

The bacteriology of biopsies differs between newly diagnosed, untreated, Crohn's disease and ulcerative colitis patients.

The bacterial community (microbiota) that inhabits the gut of humans appears to be an important source of antigens that drive the chronic immunological processes characteristic of Crohn's disease (CD) and ulcerative colitis (UC). Most of the members of the microbiota have not yet been cultured, but nucleic-acid-based methods of detection and enumeration can provide information about the community. This investigation used these methods to obtain information about the bacteria associated with mucosal surfaces in the gut of 20 CD and 15 UC patients. Biopsies were collected from inflamed and non-inflamed sites in the intestines of newly diagnosed, untreated patients. Biopsies were also collected from several intestinal sites of 14 healthy subjects. The bacterial collections associated with the biopsies were analysed by generating PCR/denaturing gradient gel electrophoresis (DGGE) profiles, the preparation of 16S rRNA gene clone libraries, and qualitative PCR to detect specific groups of bacteria. The total numbers of bacteria associated with the biopsies were determined by real-time quantitative PCR. DGGE profiles generated from the terminal ileum and various colonic regions were characteristic of each individual but differed between subjects. DGGE profiles and 16S rRNA gene libraries showed that the bacteria associated with inflamed and non-inflamed tissues did not differ. UC patients had more bacteria associated with biopsies than did CD patients (P<0.01). Statistical analysis of the composition of 16S rRNA gene libraries showed that the bacterial collections in UC and CD patients differed (P<0.05). Unclassified members of the phylum Bacteroidetes were more prevalent in CD than in UC patients. Therefore, the types and numbers of bacteria associated with biopsy samples were distinctly different for UC and CD patients. The observations made in this study should permit targeting of specific bacteriological abnormalities in investigations of the pathogenesis of inflammatory bowel diseases and provide targets for medical interventions.

Adolescent↗
PubMed2004

An evaluation of 18S rDNA approaches for the study of fungal diversity in grassland soils.

Fungal community structure and diversity in two types of agricultural grassland soil were investigated by amplified 18S ribosomal DNA restriction analysis (ARDRA) and 18S ribosomal DNA sequence analysis. These two grassland sites represent a species-rich old hay meadow and an agriculturally improved site with low floristic diversity. Two primer sets were used in combination to amplify approximately 550 bp of rDNA from three major fungal groups, the zygomycetes, basidiomycetes, and ascomycetes, and clone libraries were created for each site. 18S ARDRA was used to analyze 170 rDNA clones, and three diversity indices were calculated. A small-scale culturing analysis was also carried out and the most common isolates analyzed using ARDRA and sequence analysis. The soil fungal community revealed by the rDNA approaches was significantly different from that produced by this limited culture-based analysis. Twenty-eight soil-derived clones were sequenced, and many represented fungal taxa rarely reported in culture-based studies. The PCR-based techniques detected differences in diversity between the two fungal communities and changes in patterns of dominance that paralleled higher plant diversity. The results suggest that 18S rDNA-based approaches are a useful tool for initial screening of fungal communities, and that they represent a more comprehensive picture of the community than plate culturing.

Base Sequence↗
PubMed2007

Identification of the capsular polysaccharides in Staphylococcus aureus clinical isolates by PCR and agglutination tests.

Staphylococcus aureus is a major cause of nosocomial and community-acquired infections. The predominance of two capsular polysaccharides, types 5 and 8, on the surface of clinical isolates led to the development of a conjugate vaccine (StaphVAX) based on capsular polysaccharides types 5 and 8 conjugated to a carrier protein. We have studied the capsular phenotypes and genotypes of 195 isolates representative of all clinical syndromes that encompassed both hospital and community-acquired infections. These isolates were mainly detected in France between January 2001 and December 2004. In this population, most of clinical isolates (87%) expressed either capsular polysaccharide type 5 (42%) or 8 (45%), whereas 13% were nontypeable by the serotyping method with antibodies specific to capsular polysaccharide type 5 or 8. These 26 nontypeable strains were further serotyped and were demonstrated to express the cell wall surface antigen 336, a polyribitol phosphate N-acetylglucosamine, which resembles cell wall teichoic acid. Among methicillin-resistant Staphylococcus aureus (MRSA) strains, we found a predominance of serotype 5 for 64% of strains, whereas MSSA isolates were predominantly capsular serotype 8 (60%). All S. aureus clinical isolates included in the present study have been investigated by PCR method, demonstrating that all isolates carried either the cap5 or the cap8 locus.

Agglutination Tests↗
PubMed2005

Mid-arm circumference: an alternative measure for screening low birth weight babies.

Birth weight is a reliable and sensitive indicator for predicting the immediate or later outcome of a newborn child. In a developing country like Bangladesh, where more than 75% of deliveries occur in rural community and are mostly attended by Traditional Birth Attendants (TBA) or relatives, birth weight cannot be recorded mainly due to paucity of suitable weighing scale. To overcome the problem associated with weighing the newborn, it was considered justified to find out other simpler measurements that could be used as substitute of weighing, in order to identify low birth weight babies. A cross sectional, analytical, hospital based study was conducted at Dhaka city on 560 newborn babies born during a period of 18 months in 2000-2001 to examine relative validity of mid-arm circumference as a screening measure of low birth weight babies. Mid-arm circumference, length, head circumference, chest circumference, abdominal girth, and calf circumference were considered. The study showed a strong correlation (p < 0.001) between mid-arm circumference (r = 0.956) and birth weight, followed by calf circumference (r = 0.946) and birth weight. Other parameters were also strongly correlated (p < 0.001). The study showed that in identifying newborns of <2500 gm a mid-arm circumference of <9 cm had the best sensitivity (96.2%) and specificity (97.3%). A value of <8 cm and <6.8 cm for mid-arm circumference showed highest validity for picking up newborns weighing <2000 gm and <1500 gm respectively. Measurement of arm circumference is easier, convenient and statistically superior to other anthropometrical parameters in this work. The researchers recommend designing of simple 'Tri-colored tape' for early detection of 'At Risk' newborns in rural community for their timely management.

Anthropometry↗
PubMed2005

Impact of rapid urine antigen tests to determine the etiology of community-acquired pneumonia in adults.

STUDY OBJECTIVES: To evaluate the rapid urine antigen tests, including a new rapid immunochromatographic test (ICT) for the detection of the Streptococcus pneumoniae antigen and an enzyme immunoassay (EIA) for the detection of the Legionella antigen, in order to improve the diagnosis of community-acquired pneumonia (CAP) in adults. DESIGN: Prospective study. SETTING: A tertiary hospital in Spain. PATIENTS: We consecutively recruited 107 adults with CAP evaluated at our hospital. INTERVENTIONS: The analyses included blood and sputum cultures, pleural fluid culture (if present) and serologic studies. The detection of the Legionella pneumophila urinary antigen was performed by EIA, and the detection of S. pneumoniae antigen in urine samples was performed by counterimmunoelectrophoresis (CIE) and a rapid ICT. RESULTS: Using conventional microbiologic tests we succeeded in performing the etiologic diagnosis of 39 out of the 107 cases (36.4%). The inclusion of rapid antigen detection techniques increased the percentage of diagnosis to 54.2%, which represents a total increase of 17.8% (P=0.034). CONCLUSIONS: The data obtained in this study indicate that rapid urine antigen tests are very useful to determine CAP etiology in adults and, consequently, to quickly identify a group of patients in whom narrow spectrum antibiotics may be used.

Adolescent↗
PubMed1992

Reverse targeting in a media-promoted breast cancer screening project.

BACKGROUND: The American Cancer Society has sponsored community-based, low-cost, Breast Cancer Detection Awareness Projects throughout the United States. The authors hypothesized that these projects tend to exclude minorities and women of lower socioeconomic status--groups with a higher incidence of late-stage disease. METHODS: A cross-sectional survey was performed of participants in the 1990 Breast Screening Project in Tampa, Florida. The demographic profile of participants was compared with that predicted by 1990 census data. RESULTS: There were 13,920 women who called phone banks for additional information. Of these, 13,215 were deemed eligible and 6640 completed mammographic screening. Forty percent of participants were having mammography for the first time. Comparisons with census data indicated that elderly people, members of minority groups, and women of lower educational levels were underrepresented. CONCLUSIONS: The results of this study support the concept that "reverse targeting" occurs with these breast cancer screening projects, and recommendations for recruiting underrepresented groups are given.

Adult↗
PubMed2005

Anaerobic microbial communities in Lake Pavin, a unique meromictic lake in France.

The Bacteria and Archaea from the meromictic Lake Pavin were analyzed in samples collected along a vertical profile in the anoxic monimolimnion and were compared to those in samples from the oxic mixolimnion. Nine targeted 16S rRNA oligonucleotide probes were used to assess the distribution of Bacteria and Archaea and to investigate the in situ occurrence of sulfate-reducing bacteria and methane-producing Archaea involved in the terminal steps of the anaerobic degradation of organic material. The diversity of the complex microbial communities was assessed from the 16S rRNA polymorphisms present in terminal restriction fragment (TRF) depth patterns. The densities of the microbial community increased in the anoxic layer, and Archaea detected with probe ARCH915 represented the largest microbial group in the water column, with a mean Archaea/Eubacteria ratio of 1.5. Terminal restriction fragment length polymorphism (TRFLP) analysis revealed an elevated archaeal and bacterial phylotype richness in anoxic bottom-water samples. The structure of the Archaea community remained rather homogeneous, while TRFLP patterns for the eubacterial community revealed a heterogeneous distribution of eubacterial TRFs.

Anaerobiosis↗
PubMed2005

Computed tomographic colonography: prevalence, nature, and clinical significance of extracolonic findings in a community screening program.

OBJECTIVE: Colorectal neoplasia screening by computed tomographic colonography (CTC) may lead to the detection of incidental extracolonic findings. We report the prevalence and clinical significance of extracolonic pathology found within a community-based CTC screening program and the cost of clinical follow-up and further investigation of these findings. METHODS: A total of 432 asymptomatic subjects at an average risk of colorectal neoplasia, aged 50-69, had screening by CTC using a low radiation dose protocol. Axial images were prospectively examined for extracolonic lesions and those considered clinically relevant were followed up. All clinic visits and further investigations were tallied to calculate the incremental cost to the screening CTC. RESULTS: A total of 146 extracolonic lesions were detected in 118 (27.3%) subjects. Thirty-two (7.4%) subjects had clinically relevant extracolonic abnormalities and nine (2.1%) subjects may derive a clinical benefit from the detection of these lesions. A single CTC costed $171.12, and following up extracolonic findings resulted in an additional $24.37 (14.2%) per CTC. Limiting reporting to the aorta and kidneys would have reduced the number of subjects requiring follow-up to 14 (3.2%), and decreased the cost increment to 4.7% without detriment to clinical outcome. CONCLUSIONS: Extracolonic findings of screening CTC are common, but infrequent of clinical importance. The additional burden of following up these findings was modest and could have been further reduced if clear clinical and radiological criteria and pathways for their further investigation were defined.

Age Distribution↗
PubMed2005

Bacterial communities in petroleum oil in stockpiles.

Bacterial communities in crude-oil samples from Japanese oil stockpiles were investigated by 16S rRNA gene cloning, followed by denaturing gradient gel electrophoresis (DGGE) analysis. 16S rRNA genes were successfully amplified by PCR after isooctane treatment from three kinds of crude-oil sample collected at four oil stockpiles in Japan. DGGE profiles showed that bacteria related to Ochrobactrum anthropi, Burkholderia cepacia, Stenotrophomonas maltophilia, Propionibacterium acnes, and Brevundimonas diminuta were frequently detected in most crude-oil samples. The bacterial communities differed in the sampling time and layer. Among the predominant bacteria detected in the crude oil, only three species were found for bacteria isolated on agar plates and were related to Burkholderia, Stenotrophomonas, and Propionibacterium, while Ochrobactrum sp. could not be isolated although this species seemed to be the most abundant bacterium in crude oil from the DGGE profiles. Using an archaea-specific primer set, methanogens were found in crude-oil sludge but not in crude-oil samples, indicating that methanogens might be involved in sludge formation in oil stockpiles.

Archaea↗
PubMed2002

Leprosy in Mpumalanga Province, South Africa--eliminated or hidden?

In South Africa, leprosy has been a notifiable condition since 1921. Although the WHO elimination target of less than one case per 10,000 population has been achieved at country level, the distribution of leprosy in the country is distinctly heterogeneous, with a prominent 'leprosy belt' of greater prevalence stretching across Mpumalanga Province into northern Kwa-Zulu Natal. The highest prevalence in this 'belt' has historically been in Ermelo District. Recent trends of few newly detected leprosy patients in this district raised concerns that health system changes may have resulted in failure to detect leprosy cases. Thus a large-scale community awareness campaign was conducted followed by an intensively advertised screening programme of 3-month duration at schools and central gathering points in villages and farms from 1 June to 31 August 2000. One thousand one hundred and seventy-seven people presented for clinical screening at designated points, while 790 scholars were screened at schools and an additional 1433 people were screened at their homes by the field team. Forty-four people with skin or nervous system lesions compatible with leprosy were referred for specialized assessment and biopsy where indicated. Four new leprosy patients were diagnosed, including an elderly lady with pronounced disability. Two of these patients had prior contact with the health service due to dermatological manifestations of leprosy without diagnosis being made. All patients provided a history of close prolonged contact with known leprosy patients. Ongoing intense tracing and follow-up of close contacts of proven leprosy cases may be a more efficient method of detecting leprosy cases in areas with relatively stable populations that have accomplished 'leprosy elimination', than resource intensive community surveys.

Adult↗
PubMed2004

A community study using specified and unspecified scenarios to investigate men's views about PSA screening.

OBJECTIVE: We explored the influence of different but factual scenarios about prostate-specific antigen (PSA) screening on men's interest in having PSA screening to detect early prostate cancer. DESIGN: Cross-sectional, representative community survey. SETTING AND PARTICIPANTS: A total of 514 men (89% response fraction) aged 50-70 years randomly selected from a telephone directory database in Sydney, Australia. MAIN VARIABLES STUDIED: Demographic, health and psychological variables. MAIN OUTCOME VARIABLES: Interest in undergoing screening in response to five unspecified scenarios and, elsewhere in our interview, a specified scenario in which PSA screening was mentioned explicitly. RESULTS: When presented with a scenario describing a lack of evidence underpinning the efficacy of screening for an unspecified cancer, 61.2% of men reported that they 'probably' or 'definitely' wanted to undergo screening for an unspecified cancer. Similar proportions reported that they 'probably' or 'definitely' wanted to undergo screening even at the risk of unmasking indolent cancer (60.9%) or without expert consensus about the value of screening (62.8%). Greatest interest in screening was elicited in that scenario describing life-time risk of dying from prostate cancer (72.6%) (P < 0.001). Significantly fewer indicated they would 'probably' or 'definitely' want to undergo screening for a cancer for which there was uncertainty about treatment efficacy and known side-effects (46.1%) (P < 0.001). Increasing age was a consistent predictor of positive interest in screening. When asked later in our survey specifically about PSA screening, 68.1%'probably' or definitely' wanted PSA screening. CONCLUSION: Public health policy makers need to ensure that men are provided with the scope of medical evidence germane to prostate cancer screening and treatment, thereby potentially improving prostate cancer screening decisions.

Aged↗
PubMed2000

Psychotropic drug use, falls and hip fracture in the elderly.

The use of benzodiazepines (BZD) or other psychotropic agents is an established risk factor for falls and hip fractures. The evidence supporting this association has been based solely on history and/or prescription data. In a case-control study we monitored the intake of BZD, tricyclic antidepressants (TCA) and barbiturates in patients with hip fracture by serum analysis, and compared this measurement with drug history and prescription records. The serum was BZD positive in 41% of 82 community-dwelling patients; an equivalent by history and/or prescription records, however, was detected in only 18% (p < 0.0001). In contrast, in 82 age- and gender-matched community-dwelling control patients, there was only a minor discrepancy (3%) in BZD use between anamnestic (N = 19) and analytical (N = 21) data. In 23 patients admitted from nursing homes, a similar trend was visible (39% serum positive for BZD vs 26% by drug history). Barbiturate use (N = 2) could be neglected, and TCA intake was minor (N = 7); in each case both assessments were in accordance. In conclusion, in patients with hip fracture, BZD use is substantially more frequent than reported and previously assumed, pointing to an underestimated risk factor for this injury.

Accidental Falls↗
PubMed1992

Endogenous urinary 3-hydroxyproline has 96% specificity and 44% sensitivity for cancer screening.

A method for determining the endogenous urinary excretion levels of both 3-hydroxyproline and 4-hydroxyproline that may be useful for cancer screening of the general population and at the workplace is evaluated in this report. The excretion levels of 3-hydroxyproline and 4-hydroxproline were estimated in 97 patients with cancer and in 99 patients with various nonmalignant diseases and were compared with those of 211 healthy persons. Measurable 3-hydroxyproline peaks (by amino acid autoanalyzer) were absent from 93 samples from 211 healthy persons (44%), 50 of 99 patients with nonmalignant disease (50%), and 10 of 96 patients with cancer (10%). The levels of both 3-hydroxyproline and 4-hydroxyproline in cancer patients were significantly higher than those in healthy persons (p < 0.001 and p < 0.01, respectively) and those in patients with nonmalignant diseases (p < 0.05 and p < 0.01, respectively). Cancer patients were classified into three groups according to grade of cancer growth and invasion. The sensitivity of 3-hydroxyproline was 44% and higher than that of 4-hydroxyproline for the detection of stage II cancers (no distant metastasis); the sensitivities of both hydroxyprolines for the detection of stage I (very early cancer) were low. The specificity of these assays for healthy persons and patients with nonmalignant disease was 96% and 92% for 3-hydroxyproline, and 97% and 79% for 4-hydroxyproline, respectively. Urinary 3-hydroxyproline level should be further investigated as a cancer screening method for healthy persons in the community or the workplace, but appears unlikely to detect many cancers in the earliest stages.

Adult↗
PubMed2001

Pollution-induced community tolerance (PICT) and seasonal variations in the sensitivity of phytoplankton to atrazine in nanocosms.

Algae communities exposed to a herbicide like atrazine (PS II inhibitor) are expected to be selected and to be more tolerant to the herbicide than unexposed communities (pollution-induced community tolerance, PICT). The PICT may be an ecotoxicological tool for detecting this selective action of chronic pollution, and this method has been applied to several toxicants in experimental systems and in field studies. But the detection of PICT with PS II inhibitors has sometimes been variable. This work was done to study the long-term effects of exposure to atrazine (10 microg/l) and the PICT responses of phytoplankton communities in repeated outdoor nanocosms. Phytoplankton communities were sampled in Lake Geneva at different periods of the year and the effects of atrazine were analysed by studying community structure, biomass and primary production, and by measuring tolerance to atrazine in a short-term physiological test based on 14C incorporation. We find that PICT is a sensitive method for measuring effects. Even atrazine concentrations causing little restructuring induced tolerance in most of our experiments. But the short- and long-term responses of phytoplankton to atrazine varied between experiments, probably due to the initial compositions of the communities and environmental factors associated with seasonal parameters. The selection and detection steps of PICT to atrazine thus vary greatly with environmental conditions and the physiological adaptations of algae to the herbicide. To monitor risk assessment in aquatic systems, PICT studies applied to algae, must be investigated in the light of seasonal contaminations and seasonal events and successions.

Adaptation, Physiological↗