The importance of arterial blood gas analysis as a systemic diagnosis approach in assessing and preventing chronic diseases, from emergency medicine to the daily practice.

Blood gas analysis is a diagnostic tool to evaluate the partial pressures of gas in blood and acid-base content. The use of blood gas analysis enables a clear understanding of respiratory, circulatory, and metabolic disorders. The arterial blood gas (ABG) explicitly analyzes blood taken from an artery, assessing the patient's partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2) pH (acid/base). PaO2 indicates the oxygenation status, and PaCO2 indicates the ventilation status (chronic or acute respiratory failure). PaO2 is affected by hyperventilation, characterized by rapid or deep breathing, and hypoventilation, characterized by slow or shallow breathing. The acid-base balance tested by the ABG procedure measures the pH and PaCO2 directly, while the use of the Hasselbach equation gives the serum bicarbonate (HCO3) and base deficit or excess. The measured HCO3 is based on a strong alkali that frees all CO2 in serum, including dissolved CO2, carbamino compounds, and carbonic acid. The calculation uses a standard chemistry analysis, giving the amount of "total CO2"; the difference will amount to around 1.2 mmol/L. Though ABG is frequently ordered in emergency medicine contests for acute conditions, it may also be needed in other clinical settings. The ABG analysis shows to be an exceptional diagnostic tool, including the group of diseases known as acid-base diseases (ABDs), which include a great variety of conditions such as severe sepsis, septic shock, hypovolemic shock, diabetic ketoacidosis, renal tubular acidosis, chronic respiratory failure, chronic heart failure, and diverse metabolic diseases.

Incidence of Infection of Enterovirus 71 and Coxsackieviruses A6 and A16 among Household Contacts of Index Cases in Dong Thap Province, Southern Vietnam.

BACKGROUND: Scarce information exists about immunity to hand, foot, and mouth disease (HFMD) among household contacts of index cases in Vietnam and what that means for reducing ongoing HFMD transmission in the community. METHODS: We analyzed neutralizing antibodies (NT) and the incidence of enterovirus (EVs) infection among household contacts of index cases in a province where HFMD remains endemic. Throat swab and 2 mL blood samples from household contacts were collected at enrollment, during and after 2 weeks follow-up. RESULTS: The incidence of EV-A71 infection among household contacts was 40/84 (47.6%, 95% Cl: 36.9-58.3%), compared with 106/336 (31.5%, 95% Cl: 26.6-36.5%) for CV-A6 and 36/107 (33.6%, 95% Cl: 24.7-42.6%) for CV-A16. The incidence of CV-A6 infection was fairly constant across ages; in contrast, CV-A71 and CV-A16 had some variation across ages. At baseline, higher geometric mean titer (GMT) of EV-A71, CV-A6, and CV-A16 antibody titers was found for 25-34-year groups (range 216.3 to 305.0) compared to the other age groups. There was a statistically significant difference in GMT values of CV-A6 and CV-A16 between those who had an infection or did not have infection among households with an index case of these serotypes. CONCLUSIONS: Our results indicated that adults were becoming infected with HFMD and could be contributing to the transmission. There is, therefore, a need for considering the household setting as an additional target for intervention programs for HFMD.

Age-related changes in Egr1 transcription and DNA methylation within the hippocampus.

Aged animals show functional alterations in hippocampal neurons that lead to deficits in synaptic plasticity and changes in cognitive function. Transcription of immediate-early genes (IEGs), including Egr1, is necessary for processes such as long-term potentiation and memory consolidation. Here, we show an age-related reduction in the transcription of Egr1 in the dentate gyrus following spatial behavior, whereas in the area CA1, Egr1 is reduced at rest, but its transcription can be effectively driven by spatial behavior to levels equivalent to those observed in adult animals. One mechanism possibly contributing to these aging-related changes is an age-associated, CpG site-specific change in methylation in DNA associated with the promoter region of the Egr1 gene. Our results add to a growing body of work demonstrating that complex transcriptional and epigenetic changes in the hippocampus significantly contribute to brain and cognitive aging. © 2016 Wiley Periodicals, Inc.

Layer V perirhinal cortical ensemble activity during object exploration: a comparison between young and aged rats.

Object recognition memory requires the perirhinal cortex (PRC) and this cognitive function declines during normal aging. Recent electrophysiological recordings from young rats have shown that neurons in Layer V of the PRC are activated by three-dimensional objects. Thus, it is possible that age-related object recognition deficits result from alterations in PRC neuron activity in older animals. To examine this, the present study used cellular compartment analysis of temporal activity by fluorescence in situ hybridization (catFISH) with confocal microscopy to monitor cellular distributions of activity-induced Arc RNA in layer V of the PRC. Activity was monitored during two distinct epochs of object exploration. In one group of rats (6 young/6 aged) animals were placed in a familiar testing arena and allowed to explore five different three-dimensional objects for two 5-min sessions separated by a 20-min rest (AA). The second group of animals (6 young/6 aged) also explored the same objects for two 5-min sessions, but the environment was changed between the first and the second epoch (AB). Behavioral data showed that both age groups spent less time exploring objects during the second epoch, even when the environment changed, indicating successful recognition. Although the proportion of active neurons between epochs did not change in the AA group, in the AB group more neurons were active during epoch 2 of object exploration. This recruitment of neurons into the active neural ensemble could serve to signal that familiar stimuli are being encountered in a new context. When numbers of Arc positive neurons were compared between age groups, the old rats had significantly lower proportions of Arc-positive PRC neurons in both the AA and AB behavioral conditions. These data support the hypothesis that age-associated functional alterations in the PRC contribute to declines in stimulus recognition over the lifespan.

Age-related changes in Arc transcription and DNA methylation within the hippocampus.

The transcription of genes that support memory processes are likely to be impacted by the normal aging process. Because Arc is necessary for memory consolidation and enduring synaptic plasticity, we examined Arc transcription within the aged hippocampus. Here, we report that Arc transcription is reduced within the aged hippocampus compared to the adult hippocampus during both "off line" periods of rest, and following spatial behavior. This reduction is observed within ensembles of CA1 "place cells", which make less mRNA per cell, and in the dentate gyrus (DG) where fewer granule cells are activated by behavior. In addition, we present data suggesting that aberrant changes in methylation of the Arc gene may be responsible for age-related decreases in Arc transcription within CA1 and the DG. Given that Arc is necessary for normal memory function, these subregion-specific epigenetic and transcriptional changes may result in less efficient memory storage and retrieval during aging.

Risk factors for HIV-1 seropositivity in drug users under 30 years old in Haiphong, Vietnam.

AIMS: To assess the prevalence of HIV infection among young drug users in Haiphong and, secondarily, to document the current patterns of drug use and sexual behavior in them. Design, setting and participants. A cross-sectional survey of drug users 15-30 years old, identified from police lists and by the snowballing method between March 15 and May 30, 1999, was conducted in Haiphong City. MEASUREMENTS: Subjects (n = 520: 514 males and six females) were interviewed and donated blood specimens for HIV-1 antibody testing. FINDINGS: Mean age of the subjects was 25 years (range 15-30 years). The prevalence of HIV among injecting drug users (IDUs) was 74% and among drug users not reporting injecting was 46% (92/201). Sixty-one per cent (319) reported injecting drugs. Among injectors, 72% used heroin, and 68% had shared needles. Factors related to the presence of HIV antibody among IDUs were sharing needles (OR: 4.12) and injecting more than 31 times per month (OR: 2.37). Extramarital sex within the last 6 months was reported by 44% of single and 24% of married IDUs. CONCLUSION: The high HIV-1 prevalence in drug users and their frequent sexual mixing with the non-drug-using population suggests that preventive interventions for reduction of high-risk drug taking and sexual activities are urgently needed in these populations. Interventions through public sexually transmitted infection (STI) clinics are unlikely to have much impact, as only 16% of IDUs with an STI attended a public STI clinic.

Cross-sectional study of sexual behaviour and knowledge about HIV among urban, rural, and minority residents in Viet Nam.

OBJECTIVE: A cross-sectional survey was conducted in three districts of Quang Ninh province, Viet Nam, to find out what proportion of the people who lived there engaged in behaviour that put them at risk of becoming infected with HIV, and to measure their knowledge about HIV infection and AIDS. METHODS: The survey was conducted in a rural district, Yen Hung; a mountainous district inhabited primarily by ethnic minority groups, Binh Lieu; and an urban district, Ha Long. Participants aged 15-45 years were randomly selected from the general population to be interviewed. FINDINGS: A total of 630 people from 707 households were interviewed; 8% were not home despite repeated visits and 3% refused to participate. The prevalence of premarital intercourse ranged from 9% to 16% among married men and 4% to 7% among married women. Among single men the proportion who had ever had intercourse ranged from 6% to 16%. Fewer than 3% reported having ever had sex with a sex worker. The median number of extramarital sex partners was 1. Knowledge about HIV/AIDS was high in the urban and rural areas but low in the mountainous area. Being male and being 20-29 years old were associated with having multiple sex partners. CONCLUSION: The low prevalence of individuals reporting that they had had intercourse with sex workers and partners other than their spouse may explain the low rates of HIV infection among the heterosexual population; these rates are in contrast to the high rates of HIV infection found among injecting drug users. The association between having extramarital partners and being a younger man suggests that the tendency to have more sexual partners may increase in the future. If this happens, the potential for HIV to be spread through heterosexual sex will increase.

Lack of association between acquisition of TT virus and risk behavior for HIV and HCV infection in Vietnam.

BACKGROUND: The search for the cause of chronic hepatitis among individuals with non-A to G hepatitis has led to the discovery of a post-transfusion hepatitis-related DNA virus, designated TT virus (TTV), which, based on viral sequences, belongs to a new virus family. The principal modes of infection with TTV are poorly understood, and its role in human immunodeficiency virus type 1 (HIV-1) infection is unclear. OBJECTIVE: To determine if injection drug use (IDU) and high-risk heterosexual activity (HRHA), principal modes of acquiring HIV-1 infection, place individuals at greater risk of acquiring TTV. METHODS: The authors analyzed DNA, extracted from sera or filter paper-blotted whole blood, obtained during August 1997 and June 1998 from 324 Vietnamese (148 male; 176 female), for TTV sequences by hot-start, heminested polymerase chain reaction. RESULTS: Prevalence of TTV viremia was similar among individuals engaging in IDU or HRHA (23.4% vs. 20.2%; P > 0.5), with no age- or gender-specific differences. No association was found between TTV viremia and co-infection with HIV-1 or hepatitis C virus (HCV). Phylogenetic analysis of 30 TTV sequences revealed two distinct genotypes and four subtypes that did not segregate according to gender, HIV-1 and HCV risk behaviors, or geographic residence. CONCLUSIONS: Among HIV-1- or HCV-infected Vietnamese, who presumably acquired their infection by either the parenteral or nonparenteral route, the data indicate no clear association between acquisition of TTV infection and risk behavior for HIV-1 or HCV infection, suggesting that the usual route of TTV transmission in Vietnam is other than parenteral or sexual.