Greengenes, a chimera-checked 16S rRNA gene database and workbench compatible with ARB

A 16S rRNA gene database (http://greengenes.lbl.gov) addresses limitations of public repositories by providing chimera screening, standard alignment, and taxonomic classification using multiple published taxonomies. It was found that there is incongruent taxonomic nomenclature among curators even at the phylum level. Putative chimeras were identified in 3% of environmental sequences and in 0.2% of records derived from isolates. Environmental sequences were classified into 100 phylum-level lineages in the Archaea and Bacteria.

Greengenes, a Chimera-Checked 16S rRNA Gene Database and Workbench Compatible with ARB

A 16S rRNA gene database ( http://greengenes.lbl.gov ) addresses limitations of public repositories by providing chimera screening, standard alignment, and taxonomic classification using multiple published taxonomies. It was found that there is incongruent taxonomic nomenclature among curators even at the phylum level. Putative chimeras were identified in 3% of environmental sequences and in 0.2% of records derived from isolates. Environmental sequences were classified into 100 phylum-level lineages in the Archaea and Bacteria .

Apoptosis as a mechanism of natural resistance to HIV-1 infection in an exposed but uninfected population

BACKGROUND

Apoptosis, also known as programmed cell death, has been reported not only as a pathogenic mechanism, but also as a mechanism of resistance and control of a variety of infections. Particularly during HIV-1 infection, apoptosis is the main mechanism by which infected and uninfected CD4+ lymphocytes are eliminated. However, apoptosis as a mechanism of natural resistance to HIV infection has this far not been explored.

OBJECTIVE

To determine whether apoptosis could explain, at least in part, the natural resistance to HIV infection observed in some exposed but uninfected individuals (ESN).

RESULTS

Our data shows that peripheral blood monocytes in the ESN group has a predisposition to undergo spontaneous apoptosis, as well as apoptosis induced by HIV infection in vitro, compared with monocyte population from the control group at low risk of HIV infection.

CONCLUSIONS

These findings suggest that, in some ESN individuals, monocytes could play an important role in the control of HIV infection by undergoing apoptosis. However, since the variability among individuals is large, studies with larger cohorts focusing in monocyte apoptosis as pathogenic mechanisms are required.

Latin America's present and future challenges in toxicology education

Industrialization that Latin America has experienced during the past 50 years, the increase of population and the growth of chemical-related industries has generated a variety of environmental problems that must be addressed. After assessing these profound changes, greater emphasis should be placed on the study of environmental health and toxicology. Latin American countries face many problems that are common to other developing nations. Therefore, there is a demand for safety assessment and regulatory control of chemicals that create a need for increasing numbers of toxicologists. To meet this demand, educational programs in toxicology have to be designed. This paper utilizes a consultation questionnaire that includes toxicology-network members, scientists and educational institutions where toxicology is taught. An analysis of the information collected is made, with an emphasis on what we currently lack and on future challenges for toxicology professionals. Although the response from the study institutions was 65% (13 countries out of 20), the paper aims to assess the present situation of toxicology. The convenience for a certification/recognition for toxicologists is also evaluated. Action needs to be taken to promote scientific development based on regional specific needs that require increasing at the number of toxicology programs, and promoting of cooperation between academics and researchers. Among the limitations we have are the variability of curricula, objectives and priorities. The increasing globalization of markets and regulations requires the harmonization of graduate/postgraduate programs to ensure that risk assessment and management are dealt with uniformly. Cooperation among our countries and international assistance should play a more prominent role in the promotion of regional integration and the more efficient utilization of international experience in defining educational policies.

Human skin keratinocytes modified by a Friend-derived retroviral vector: a functional approach

The goal of this study was to test the efficiency and possible functional effects of a Friend Leukemia derived retrovirus vector (FOCH29-NeoR) on cultured human keratinocytes, obtained from skin biopsy samples. The keratinocytes were grown and infected with filtered Friend vector supernatant. After one or two doses of infection, one duplicate of the culture was submitted to selection with G418; the other one was utilized for DNA extraction and PCR modification detection. Transduction efficiency was 46.66 percent and 47.22 percent for one and two doses of infection respectively (range 100 to 15 %). Colony Forming Efficiency (CFE) assays were done with Rodhamine-B staining in nonselected modified cultures and negative controls. There was no difference in CFE (% CFE= 10.74+/-6.53 negative control vs % CFE= 9.22+/-5.45 with one dose, and % CFE= 10.03+/-5.74 with two doses of infection). Nevertheless, the cell-cycle analysis done by Propidium Iodade (PI) incorporation and colchicine-arrest assays in nonselected transduced and nontransduced cells show that transduced keratinocytes have a longer time to enter G2. As far as we know, this is the first report of retroviral transduction-induced changes in the cell cycle done on human keratinocytes. This observation is very important because retroviral vectors of genes, such as platelet derived growth factor (PDGF) or vascular endothelial growth factor (VEGF), are expected to facilitate the implementation of these modified cultures for tissue grafting and skin substitute development and potentiate the effectiveness of the grafts.

[New CT and MR imaging techniques in non-traumatic neurological emergencies]

New CT and MR imaging techniques used for non-traumatic neurologic emergencies (represented mostly by ischemic stroke) fulfil the exigency to know quickly and with high accuracy the presence of abnormalities in cerebral perfusion, with the final aim to practise immediately all the treatments needed to prevent the progression of the neurologic damage, by selecting those patients to undergo fibrinolysis, which is useless and not indicated in many occasions. The diagnosis of ischemia is only the first goal reached by these new diagostic tools, while it is nowdays possible and required to stratify the risk factors for the therapy and to accurate select those patients candidates to fibrolnilysis, in order to minimize the risck related to the inadequate treatment choice.

Computed tomography-guided and arthroscopically controlled en bloc retrograde resection of a juxta-articular osteoid osteoma of the tibial plateau

Osteoid osteoma represents approximately 10% to 11% of all the benign bone tumors. The localization at the articular and juxta-articular level of the knee is an atypical picture that causes both diagnostic and therapeutic problems. We present the case of an osteoid osteoma of the lateral tibial plateau just beneath the joint level. The lesion was removed by a rear-entry computed tomography (CT)-guided drill under arthroscopic control and the bony defect filled with bone graft harvested from the proximal tibial metaphysis. Postoperative CT scans at 3 months, and 1 and 2 years were performed. The result of the kneeling test to evaluate donor-site morbidity 1 year after the surgery was negative. There were no immediate or delayed complications. Currently (2 years postoperatively), the patient has no pain and has gone back to his normal active daily lifestyle and routines. The follow-up CT scan 2 years after surgery showed complete excision of the lesion and perfect positioning of the bone graft. This new approach/technique enabled us to avoid damaging the proximal structures, to examine the lesion, and to fill the bony defect. Moreover, as shown by CT scan at follow-up, iatrogenic lesions to the cartilage of the tibial plateau were not reported.

[Neuroimaging of Alzheimer disease: current role and future potential]

Alzheimer disease (AD), the most common cause of dementia in the elderly, is a progressive neurodegenerative disorder, associated with deterioration in cognition and behaviour. With the availability of newer drugs for symptoms treatments there is a general agreement to the need of an early diagnosis and an the development of new sensitive tools, to identify and/or monitor early cerebral changes, suggestive for AD. CT and MRI are recommended for routine evaluation, in order to exclude treatable causes of dementia and to exactly evaluate the degree of cerebral atrophy and the presence of parenchymal signal abnormalities. Functional imaging, including PET, SPECT and functional MR techniques, are able to investigate physiological cerebral function, such as blood perfusion, metabolism, activation, molecular composition and water diffusibility, and have the potential to detect subtle pathological changes earlier during course of disease. MRI can provide both an accurate morphological assessment and a functional evaluation. Further investigations are needed to precisely define which will be the role of the different MR techniques. Most likely an exhaustive evaluation of AD will include information obtained by conventional and functional imaging, combined with clinical, laboratory and genetic findings.

[Trihalomethanes in the drinking water of Carabobo State, Venezuela]

OBJECTIVE

Disinfection of water with chlorine in water treatment plants leads to the formation of trihalomethanes (THMs). These compounds are associated with adverse health effects. The aim of this study was to analyze THM concentrations in the water provided for human consumption in the two main water treatment systems of Carabobo State: the Alejo Zuloaga plant and the Pao-Cachinche reservoir, which form the Central Regional System I (CRS I), and the Lucio Baldo Soules plant and the Pao-La Balsa reservoir, which form the Central Regional System II (CRS II).

METHODS

We analyzed 144 water samples collected in 6 samplings carried out in 2000 and 2001. THM concentrations were determined by gas chromatography using the headspace technique. The concentrations of the following THMs were measured: chloroform (CHCl3), bromoform (CHBr3), chlorodibromomethane (CHBr2Cl) and bromodichloromethane (CHCl2Br).

RESULTS

The concentration of total THMs was between 47.84 g/l and 94.23 g/l. CHCl3 was the most commonly formed compound representing 83% of all THMs in the CRS I and 82% in the CRS II. The concentrations of total THMs in the CRS I, specifically in the Baja and San Diego networks, were significantly higher (p < 0.05) than permissible levels set by the American Environmental Protection Agency (80 g/l) for the sum of all four THMs.

CONCLUSIONS

The results show that in the area studied there is a risk of adverse health effects due to THMs in drinking water, especially in the Baja and San Diego networks.

B cell specificity contributes to the outcome of diabetes in nonobese diabetic mice

Type I diabetes mellitus (TIDM) is an autoimmune disorder characterized by T cell-mediated destruction of insulin-producing beta cells in the pancreas. In the nonobese diabetic (NOD) model of TIDM, insulitis and diabetes are dependent on the presence of B lymphocytes; however, the requirement for specificity within the B cell repertoire is not known. To determine the role of Ag-specific B cells in TIDM, V(H) genes with different potential for insulin binding were introduced into NOD as H chain transgenes. VH125 H chain combines with endogenous L chains to produce a repertoire in which 1-3% of mature B cells are insulin specific, and these mice develop accelerated diabetes. In contrast, NOD mice harboring a similar transgene, VH281, with limited insulin binding develop insulitis but are protected from TIDM. The data indicate that Ag-specific components in the B cell repertoire may alter the course of TIDM.

[Role of magnetic resonance in shoulder disease]

Next to the knee, the shoulder is the most common joint to be referred for MRI. Excellent soft tissue contrast and multiplanar acquisition provide optimal assessment of muscle, tendons, hyaline and fibrous cartilage, joint capsule, fat, bursae and bone marrow. In this article the most common indications for shoulder MRI are reviewed and discussed, but we focused primarily on the rotator cuff syndrome and shoulder instability. Correct diagnosis requires the use of appropriate pulse sequences and imaging planes, proper patient positioning, and a satisfactory surface coil. Moreover, technical improvements continuously augment the ability of MRI to study the shoulder; for example Magnetic Resonance arthrography is superior to the other imaging techniques in evaluation of glenohumeral joint. This interdependence between technical development in MRI and clinical advance in shoulder therapy ensures that MRI will continue to play an important role in the routine management of patients with shoulder disease.

Occupational exposure to airborne mercury during gold mining operations near El Callao, Venezuela

OBJECTIVE

The National Institute for Occupational Safety and Health (NIOSH) recently conducted a cross-sectional study during gold mining operations near El Callao, Venezuela. The purpose of the study was to assess mercury exposures and mercury-related microdamage to the kidneys. The study consisted of concurrent occupational hygiene and biological monitoring, and an examination of the processing techniques employed at the different mining facilities. Mercury was used in these facilities to remove gold by forming a mercury-gold amalgam. The gold was purified either by heating the amalgam in the open with a propane torch or by using a small retort.

METHODS

Thirty-eight workers participated in this study. Some participants were employed by a large mining company, while others were considered "informal miners" (self-employed). Mercury exposure was monitored by sampling air from the workers' breathing zones. These full-shift air samples were used to calculate time-weighted average (TWA) mercury exposure concentrations. A questionnaire was administered and a spot urine sample was collected. Each urine sample was analyzed for mercury, creatinine, and N-acetyl-beta-D-glucosaminidase (NAG).

RESULTS

The range for the 8-h TWA airborne mercury exposure concentrations was 0.1 to 6,315 micrograms/m3, with a mean of 183 micrograms/m3. Twenty percent of the TWA airborne mercury exposure measurements were above the NIOSH recommended exposure limit (REL) of 50 micrograms/m3, and 26% exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25 micrograms/m3. The mean urine mercury concentration was 101 micrograms/g creatinine (microgram/g-Cr), and the data ranged from 2.5 to 912 micrograms/g-Cr. Forty-two percent of the study participants had urine mercury concentrations that exceeded the ACGIH biological exposure index (BEI) of 35 micrograms/g-Cr. Urinary NAG excretion is considered a biological marker of preclinical, nonspecific microdamage to the kidney's proximal tubule cells. The mean urine NAG concentration was 3.6 International Units/g-Cr (IU/g-Cr) with a range of 0.5 to 11.5 IU/g-Cr. Three workers had urine NAG levels in excess of the reference values. Correlation analyses found statistically significant correlations between airborne mercury exposure and urine mercury level (P = 0.01), and between urine mercury level and urine NAG excretion (P = 0.01). In addition, the airborne mercury exposure data and urine mercury data were segregated by job tasks. A Wilcoxon rank sum test revealed significant correlations between tasks and mercury exposure (P = 0.03), and between tasks and urine mercury level (P = 0.02).

CONCLUSIONS

The tasks with the highest mean airborne mercury exposures were "burning the mercury-gold amalgam" and "gold refining/smelting". Recommendations were provided for improving the retort design to better contain mercury, for ventilation in the gold shops, and for medical surveillance and educational programs.

[Central nervous system malformations in a Clinical Hospital of Universidad de Chile and in Chilean maternity hospitals that participated in the Latin American Collaborative Study of Congenital Malformations (ECLAMC)]

BACKGROUND

In Chile, the rates of central nervous system congenital malformations at birth remain high, when compared with the rest of the world.

AIM

To report the rates of central nervous system congenital malformations in Chilean hospitals.

MATERIAL AND METHODS

Using the ECLAMC protocol, every malformed newborn or stillbirth, weighing more than 500 g at birth is registered using a standard protocol, and the next non malformed child of the same sex born in the same hospital is assigned as control.

RESULTS

The rates of central nervous system congenital malformations are higher at the University of Chile Clinical Hospital than in the rest of Chilean hospitals or Latin American Hospitals. There are significantly higher rates of anencephalia in Concepcion and spina bifida in Valdivia, Rancagua and Concepcion. In the University of Chile Clinical Hospital, global annual rates have a negative slope of -0.0259 per 1000 born alive, with a correlation coefficient of -0.125 (p < 0.05). The slope is positive among children born alive, with an annual rate increase of 0.071. Among stillbirths, the slope is -0.47 per 1000 born alive. Sixty two percent of malformed children were female. Among children with neural tube defects, 30% had a malformed relative and, of these, 66% had the same malformation.

CONCLUSIONS

Family clustering of neural tube defects, supports the influence of a genetic factor influencing their appearance.