Widespread pH abnormalities in patients with malformations of cortical development and epilepsy: a phosphorus-31 brain MR spectroscopy study

Lactic Acidosis in Patients with Solid Cancer

Significance: Cancer-associated tissue-specific lactic acidosis stimulates and mediates tumor invasion and metastasis and is druggable. Rarely, malignancy causes systemic lactic acidosis, the role of which is poorly understood. Recent Advances: The understanding of the role of lactate has shifted dramatically since its discovery. Long recognized as only a waste product, lactate has become known as an alternative metabolism substrate and a secreted nutrient that is exchanged between the tumor and the microenvironment. Tissue-specific lactic acidosis is targeted to improve the host body's anticancer defense and serves as a tool that allows the targeting of anticancer compounds. Systemic lactic acidosis is associated with poor survival. In patients with solid cancer, systemic lactic acidosis is associated with an extremely poor prognosis, as revealed by the analysis of 57 published cases in this study. Although it is considered a pathology worth treating, targeting systemic lactic acidosis in patients with solid cancer is usually inefficient. Critical Issues: Research gaps include simple questions, such as the unknown nuclear pH of the cancer cells and its effects on chemotherapy outcomes, pH sensitivity of glycosylation in cancer cells, in vivo mechanisms of response to acidosis in the absence of lactate, and overinterpretation of in vitro results that were obtained by using cells that were not preadapted to acidic environments. Future Directions: Numerous metabolism-targeting anticancer compounds induce lactatemia, lactic acidosis, or other types of acidosis. Their potential to induce acidic environments is largely overlooked, although the acidosis might contribute to a substantial portion of the observed clinical effects. Antioxid. Redox Signal. 37, 1130-1152.

Targeting acidity in cancer and diabetes

While cancer is commonly described as "a disease of the genes", it is also a disease of metabolism. Indeed, carcinogenesis and malignancy are highly associated with metabolic re-programming, and there is clinical evidence that interrupting a cancer's metabolic program can improve patients' outcomes. Notably, many of the metabolic adaptations observed in cancer are similar to the same perturbations observed in diabetic patients. For example, metformin is commonly used to reduce hyperglycemia in diabetic patients, and has been demonstrated to reduce cancer incidence. Treatment with PI3K inhibitors can induce hyperinsulinemia, which can blunt therapeutic efficacy if unchecked. While commonalities between metabolism in cancer and diabetes have been extensively reviewed, here we examine a less explored and emergent convergence between diabetic and cancer metabolism: the generation of lactic acid and subsequent acidification of the surrounding microenvironment. Extracellular lactic acidosis is integral in disease manifestation and is a negative prognostic in both disease states. In tumors, this results in important sequela for cancer progression including increased invasion and metastasis, as well as inhibition of immune surveillance. In diabetes, acidosis impacts the ability of insulin to bind to its receptor, leading to peripheral resistance and an exacerbation of symptoms. Thus, acidosis may be a relevant therapeutic target, and we describe three approaches for targeting: buffers, nanomedicine, and proton pump inhibitors.

Brain aging: Evaluation of pH using phosphorus magnetic resonance spectroscopy

AIM

Very important aspects of aging include age-related changes occurring in the brain. The aim of the present study was to identify the standard pH value in the entire brain volume using phosphorus magnetic resonance spectroscopy in healthy individuals of both sexes in different age groups, and then to determine whether there are differences in these values.

METHODS

A total of 65 individuals aged 20-32 years (mean age 24.5 ± 2.1 years, 31 women and 34 men) and 31 individuals aged 60-81 years (mean age 64.9 ± 5.5 years, 17 women and 14 men) were studied. The phosphorus magnetic resonance spectroscopy examination was carried out using a 1.5-T magnetic resonance system. The signal was acquired from the volume of interest that covered the whole brain.

RESULTS

A vast majority of the examined individuals had slightly alkaline brain pH regardless of age. In the ≥20 years group, pH was 7.09 ± 0.11, and in the ≥60 years group, the average pH was 7.03 ± 0.05. This comparison of the pH identified in all the tested individuals shows a negative correlation of pH with age.

CONCLUSIONS

The present findings might provide a valuable basis for further research into "healthy aging" as well as pathology in older adults. Geriatr Gerontol Int 2018; 18: 881-885.

PH Measurements of the Brain Using Phosphorus Magnetic Resonance Spectroscopy ((31)PMRS) in Healthy Men - Comparison of Two Analysis Methods

Background

Intracellular pH provides information on homeostatic mechanisms in neurons and glial cells. The aim of this study was to define pH of the brain of male volunteers using phosphorus magnetic resonance spectroscopy (³¹PMRS) and to compare two methods of calculating this value.

Material/Methods

In this study, 35 healthy, young, male volunteers (mean age: 25 years) were examined by ³¹PMRS in 1.5 T MR system (Signa Excite, GE). The FID CSI (Free Induction Decay Chemical Shift Imaging) sequence was used with the following parameters: TR=4000 ms, FA=90°, NEX=2. Volume of interest (VOI) was selected depending on the size of the volunteers’ brain (11–14 cm³, mean 11.53 cm³). Raw data were analyzed using SAGE (GE) software.

Results

Based on the chemical shift of peaks in the ³¹PMRS spectrum, intracellular pH was calculated using two equations. In both methods the mean pH was slightly alkaline (7.07 and 7.08). Results were compared with a t-test. Significant difference (p<0.05) was found between these two methods.

Conclusions

The ³¹PMRS method enables non-invasive in vivo measurements of pH. The choice of the calculation method is crucial for computing this value. Comparing the results obtained by different teams can be done in a fully credible way only if the calculations were performed using the same formula.

Malformations of cortical development: 3T magnetic resonance imaging features

Malformation of cortical development (MCD) is a term representing an inhomogeneous group of central nervous system abnormalities, referring particularly to embriyological aspect as a consequence of any of the three developmental stages, i.e., cell proliferation, cell migration and cortical organization. These include cotical dysgenesis, microcephaly, polymicrogyria, schizencephaly, lissencephaly, hemimegalencephaly, heterotopia and focal cortical dysplasia. Since magnetic resonance imaging is the modality of choice that best identifies the structural anomalies of the brain cortex, we aimed to provide a mini review of MCD by using 3T magnetic resonance scanner images.

DTI-based tractography of the arcuate fasciculus in patients with polymicrogyria and language disorders

OBJECTIVES

To assess the integrity of the arcuate fasciculus (AF) with diffusion tensor imaging (DTI) and tractography in patients with congenital polymicrogyria (PMG) and language disorders.

METHODS

Twelve patients with PMG and 12 matched controls were prospectively evaluated with DTI (32 gradient encoding directions, b-value=1000 s/mm(2)) at 3.0T. The AF was virtually dissected with a deterministic streamline approach. DTI metrics included FA (fractional anisotropy), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). A subset of patients (n=4) was evaluated to assess cognitive performance and language skills.

RESULTS

Qualitative evaluation revealed several abnormalities in tracts size and architecture in nearly all PMG patients. Remarkably, in 3 patients with bilateral PMG, the AF was not delineated on both hemispheres. In comparison to controls, patients exhibited significant decrease of FA (p=0.003) in addition to increase of RD (p=0.03) in the right AF, whereas there was significant increase of MD in the left AF (p=0.04). All 4 patients with language evaluation had suboptimal performance on lexical fluency and prosodic linguistic.

CONCLUSIONS

DTI and tractography suggest that the AF is severely disrupted in patients with PMG, providing an anatomical in vivo substrate for the language disorders commonly associated with these cortical malformations.