Serum l-lactate and pyruvate in HIV-infected patients with and without presumed NRTI-related adverse events compared to healthy volunteers

A novel immobilization fluorescence capillary analysis method and its applications

Fluorescence capillary analysis (FCA) realizes trace-level analysis of micro-volume samples; it is easy to operate, extremely low in analytical cost and can significantly lessen environmental pollution from analytical chemistry waste. FCA has the characteristics of green analytical chemistry and has been applied in clinical, biochemical, pharmaceutical, food safety and other fields. FCA basically involves a micro-volume glass capillary, a capillary holder and an ordinary fluorescence detector. The capillary is not only a container for chemical reaction and detection but also functions as a carrier to immobilize enzymes, gene probes or reagents; it can be used repeatedly or can be disposable. In analysis, the capillary which is modified with functional reagents sucks in a measured liquid for the reaction and is then inserted into the holder within the fluorescent detector for measurement. The immobilized FCA method has been successfully used in the determination of reduced coenzyme I, ethanol in liqueur, lactic acid in dairy products, pyruvic acid and glucose in serum, trace-level sulfated bile acid in urine, the ratio of pyruvic/lactic acid in serum, and pyruvic acid in cells as well as in DNA end-labeling and dyeing methods. Further, FCA can also be extended to capillary arrays to complete multipurpose simultaneous determinations and can be combined with mobile phones as fluorescence detectors for use in mobile health analytical technology. FCA will produce considerable social benefits in medicine, pharmacy, fermentation of food, environmental protection and other fields. Therefore, the relevant contents are presented in this tutorial review.

Neurological and psychiatric adverse effects of antiretroviral drugs

Antiretroviral drugs are associated with a variety of adverse effects on the central and peripheral nervous systems. The frequency and severity of neuropsychiatric adverse events is highly variable, with differences between the antiretroviral classes and amongst the individual drugs in each class. In the developing world, where the nucleoside reverse transcriptase inhibitor (NRTI) stavudine remains a commonly prescribed antiretroviral, peripheral neuropathy is an important complication of treatment. Importantly, this clinical entity is often difficult to distinguish from human immunodeficiency virus (HIV)-induced peripheral neuropathy. Several clinical trials have addressed the efficacy of various agents in the treatment of NRTI-induced neurotoxicity. NRTI-induced neurotoxicity is caused by inhibition of mitochondrial DNA polymerase. This mechanism is also responsible for the mitochondrial myopathy and lactic acidosis that occur with zidovudine. NRTIs, particularly zidovudine and abacavir, may also cause central nervous system (CNS) manifestations, including mania and psychosis. The non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz is perhaps the antiretroviral most commonly associated with CNS toxicity, causing insomnia, irritability and vivid dreams. Recent studies have suggested that the risk of developing these adverse effects is increased in patients with various cytochrome P450 2B6 alleles. Protease inhibitors cause perioral paraesthesias and may indirectly increase the relative risk of stroke by promoting atherogenesis. HIV integrase inhibitors, C-C chemokine receptor type 5 (CCR5) inhibitors and fusion inhibitors rarely cause neuropsychiatric manifestations.

Mitochondrial toxicity studied with the PBMC of children from the Chinese national pediatric highly active antiretroviral therapy cohort

As the backbone of highly active antiretroviral therapy (HAART), nucleoside reverse transcriptase inhibitors (NRTIs) have effectively improved outcomes for HIV-infected patients. However, long-term treatment with NRTIs can cause a series of pathologies associated with mitochondrial toxicity. To date, the status and mechanism of mitochondrial toxicity induced by NRTIs are still not clear, especially in HIV-infected children. As part of the national pediatric HAART program in China, our study focused on mitochondrial toxicity and its potential mechanism in HIV-1-infected children who were divided into two groups based on their duration of treatment with NRTIs: one group received treatment for less than 36 months and one group was treated for 36 to 72 months. The control group comprised age-matched non-HIV-infected children. Blood lactic acid and ATP levels in peripheral blood mononuclear cells (PBMCs) were measured to evaluate mitochondrial function, and mtDNA copies and mutations in PBMCs were determined for detecting mtDNA lesions. Simultaneously, TK2 and P53R2 gene expression in PBMC was measured. As compared with the control group, blood lactic acid levels in both NRTI treatment groups were significantly higher, whereas ATP levels and mtDNA mutation rates in PBMCs did not differ between the control and the two NRTI treatment groups. Both NRTI treatment groups exhibited significant mtDNA loss. N Moreover, we found that P53R2 mRNA expression and protein levels were significantly reduced in both treatment groups and that TK2 mRNA expression and protein levels were induced in the long-term NRTI treatment group. These results suggest that mitochondrial toxicity occurs in long-term HAART patients and that P53R2 and TK2 levels in PBMCs are useful biomarkers for detecting mitochondrial toxicity in patients on long-term treatment with NRTIs.

Lactic acidosis: recognition, kinetics, and associated prognosis

Lactic acidosis is a common condition encountered by critical care providers. Elevated lactate and decreased lactate clearance are important for prognostication. Not all lactate in the intensive care unit is due to tissue hypoxia or ischemia and other sources should be evaluated. Lactate, in and of itself, is unlikely to be harmful and is a preferred fuel for many cells. Treatment of lactic acidosis continues to be aimed the underlying source.

Hormonal contraception and HIV-positive women: metabolic concerns and management strategies

As HIV-positive women live longer lives, and as testing for HIV becomes more routine, clinicians can expect to see more HIV-positive women in their practices. The need to be aware of management issues particular to this population becomes increasingly important. Metabolic dysregulation is a common, long-term complication associated with HIV and is one of the most difficult to manage. Hormonal contraception also is associated with metabolic dysregulation. As more HIV-positive women choose long-term, reversible contraception, the potential for concomitant and additive side effects, and the need for careful, proactive management strategies to avoid these complications, will become more important. This article reviews research detailing the metabolic dysfunction associated with hormonal contraception and with HIV-seropositivity. It highlights reasons for concern regarding the potential, although as yet theoretical, increased risk for metabolic dysfunction when hormonal contraception is used in the presence of HIV. Suggestions for management strategies for women living with HIV who choose to use hormonal contraception are presented. These strategies should be viewed as suggestions for management until substantitive research becomes available.

Risk factors for lactic acidosis and severe hyperlactataemia in HIV-1-infected adults exposed to antiretroviral therapy

BACKGROUND

Severe hyperlactataemia and lactic acidosis are rare serious complications of antiretroviral therapy (ART).

METHODS

Lactic acidosis was defined as pH < 7.35, bicarbonate < 20 mmol/l and raised lactate; hyperlactataemia as two consecutive lactates > 5 mmol/l. The case-control study of 110 cases and 220 controls(two randomly selected from treated patients by centre and calendar year) from centres in 10 countries included 40 (36.4%) female cases and 40 female controls (18.2%) (P < 0.001). Median age was 42.4 years [interquartile range (IQR, 36.0-52.5] for cases and 40 (IQR, 35.0-47.1) for controls (P = 0.013). More cases were nonwhite (41.9%) than controls (31.2%) (P = 0.032). Cases had a shorter duration of exposure to dideoxynucleosides.

RESULTS

After adjusting for age, gender and current CD4 cell count, hyperlactataemia/lactic acidosis remained associated with exposure to didanosine in every category of exposure duration but was most strongly associated with exposure < 12 months. In a separate multivariable model, apart from exposure to stavudine, didanosine, or even more strongly both, age above 40 years [odds ratio (OR), 2.6; 95% confidence interval (CI), 1.08-6.29], female gender (OR, 5.97; 95% CI, 1.92-18.5) and advanced immunosuppression were independent associations (CD4 cell count 200-349, 100-199 and < 100 cells/mul: OR, 3.89, 7.58 and 8.11, respectively).

INTERPRETATION

Hyperlactataemia/lactic acidosis was associated with exposure to dideoxynucleosides, female gender, advanced immunosuppression and possibly ethnicity. This has important consequences for choice of ART in resource-limited settings. The association with shorter duration of exposure may support the hypothesis of susceptibility in a small proportion of patients.

Limitation of exercise capacity in nucleoside-treated HIV-infected patients with hyperlactataemia

BACKGROUND

Inhibition of DNA polymerase gamma by nucleoside reverse transcriptase inhibitors (NRTIs) can cause mitochondrial dysfunction and cellular toxicity. Hyperlactataemia, which is a consequence of a shift in the metabolism of pyruvate, is an indicator of nucleoside-related mitochondrial toxicity.

METHODS

We evaluated exercise and oxidative capacities as well as circulatory and ventilatory responses to exercise in 24 HIV-infected patients on NRTIs presenting hyperlactataemia [mean (+/-standard deviation) fasted lactate=3.5+/-1.1 mmol/L]; 27 NRTI-treated patients with normal baseline lactate concentrations were used as controls (mean fasted lactate=1.6+/-0.3 mmol/L).

RESULTS

In the patients with hyperlactataemia, the average peak work capacity (1.7+/-0.6 W/kg) and peak oxygen consumption (VO(2)) (21+/-4 mL/kg/min) were significantly lower (P<0.01) than in control subjects (work, 2.1+/-0.4 W/kg; VO(2), 25+/-4 mL/kg/min). The capacity to increase oxygen extraction during exercise was significantly diminished in the hyperlactataemia group, as shown by a low peak systemic arteriovenous oxygen difference (a-vO(2)) difference compared with controls (11+/-3 vs 14+/-3 mL/dL; P=0.008), and as indicated by a linear correlation between VO(2) and systemic a-vO(2) difference (r(2)=0.76). During exercise, the increases in cardiac output relative to VO(2) (mean Delta cardiac output (Q)/DeltaVO(2)=8+/-3.6) and ventilation (mean Delta ventilation (VE)/DeltaVO(2)=48.6+/-13.2) were significantly higher in hyperlactataemia patients compared with controls (mean cardiac output Delta(Q)/DeltaVO(2)=6+/-2; mean DeltaVE/DeltaVO(2)=42+/-12.7; P=0.03).

CONCLUSIONS

The degree of exercise limitation in patients with nucleoside-related mitochondrial toxicity correlates directly with the severity of impaired muscle oxidative phosphorylation, as indicated by the capacity for muscle oxygen extraction. Exaggerated circulatory and ventilatory responses to exercise are direct consequences of the level of impaired muscle oxidative phosphorylation.

A brief overview of mechanisms of mitochondrial toxicity from NRTIs

Nucleoside reverse transcriptase inhibitors (NRTIs) in combinations with other antiretrovirals (highly active antiretroviral therapy, HAART) are the cornerstones of AIDS therapy, turning HIV infection into a manageable clinical entity. Despite the initial positive impact of NRTIs, therapeutic experience revealed serious side effects that appeared to originate in the mitochondria and which ultimately manifested as dysfunction of that organelle. It may be reasonable to consider that as the AIDS epidemic continues and as survival with HIV infection is prolonged by treatment with HAART, long-term side effects of NRTIs may become increasingly common. This consideration may be underscored in children who are born to HIV-infected mothers who received NRTI therapy in utero during gestation. The long-term effect of that NRTI exposure in utero is not clear yet. This review examines some proposed mechanisms of NRTI mitochondrial toxicity, including genetic predisposition, defects in mitochondria DNA replication, the encompassing "DNA pol-gamma hypothesis," the relationship between mitochondrial nucleotide and NRTI pools, mitochondrial DNA mutation and dysfunction, and oxidative stresses related to HIV infection and NRTIs. Mechanisms of mitochondrial toxicity are reviewed with respect to key cell biological, pathological, and pharmacological events.

Human malarial disease: a consequence of inflammatory cytokine release

Malaria causes an acute systemic human disease that bears many similarities, both clinically and mechanistically, to those caused by bacteria, rickettsia, and viruses. Over the past few decades, a literature has emerged that argues for most of the pathology seen in all of these infectious diseases being explained by activation of the inflammatory system, with the balance between the pro and anti-inflammatory cytokines being tipped towards the onset of systemic inflammation. Although not often expressed in energy terms, there is, when reduced to biochemical essentials, wide agreement that infection with falciparum malaria is often fatal because mitochondria are unable to generate enough ATP to maintain normal cellular function. Most, however, would contend that this largely occurs because sequestered parasitized red cells prevent sufficient oxygen getting to where it is needed. This review considers the evidence that an equally or more important way ATP deficiency arises in malaria, as well as these other infectious diseases, is an inability of mitochondria, through the effects of inflammatory cytokines on their function, to utilise available oxygen. This activity of these cytokines, plus their capacity to control the pathways through which oxygen supply to mitochondria are restricted (particularly through directing sequestration and driving anaemia), combine to make falciparum malaria primarily an inflammatory cytokine-driven disease.