Abbreviated half-lives and impaired fuel utilization in carnitine palmitoyltransferase II variant fibroblasts. PLoS One. 2015;10:e0119936. [PMID: 25781464 PMCID: PMC4364069 DOI: 10.1371/journal.pone.0119936]

Novel metabolomics markers are associated with pre-clinical decline in hand grip strength in community-dwelling older adults

BACKGROUND

Hand grip strength (HGS) has been proposed as a robust predictor for frailty and sarcopenia. Hence, identifying biomarkers for declining HGS accompanying aging could deepen our understanding of the biological underpinnings, informing pre-emptive intervention. Acylcarnitines (ACs) are metabolites generated by fatty acid metabolism in the mitochondria and are dysregulated in multiple disorders affecting the musculature. However, they have not been comprehensively profiled and examined regarding their utility in predicting variability in declining HGS, longitudinally. Thus, we aimed to: 1) validate previous findings on insignificant cross-sectional association between ACs and HGS, and 2) examine whether baseline ACs were associated with both decline and variability in HGS over 18 months, in community-dwelling older adults.

METHODS

We included participants who had HGS measured with dynamometer longitudinally (N = 121). We quantified ACs by targeted plasma metabolomics profiling. Multivariable linear regressions were then performed.

RESULTS

Cross-sectionally, ACs were not significantly associated with HGS. Longitudinally, baseline short-chain dicarboxylic and hydroxylated acylcarnitines (AC-DC/-OH) levels were inversely associated with and significantly explained the variability in 18-month decline in HGS. A specific AC species, the C4-OH, accounted for most of the variance explained.

CONCLUSIONS

We showed novel biomarkers for declining HGS, furthering molecular understanding and informing nutritional pre-emptive programs.

Rhabdomyolysis caused by carnitine palmitoyltransferase 2 deficiency: A case report and systematic review of the literature

Carnitine palmitoyltransferase 2 deficiency is an inherited metabolic disorder involving a deficiency in a mitochondrial enzyme necessary for long chain fatty acid oxidation, and therefore decreased utilisation of fatty acids. The adult form of this condition leads to recurrent rhabdomyolysis triggered by exercise, fasting and infection. It is a very rare condition with only a few hundred reported cases worldwide. Here we present a case of severe rhabdomyolysis in the context of carnitine palmitoyltransferase 2 deficiency in which major organ involvement was avoided, and organ support was not needed. This prompted us to perform a systematic review of the existing case reports in the literature to ascertain the most frequent patterns of organ involvement and assess the outcomes that are seen in these patients. Our findings suggest that these patients most frequently develop isolated renal failure, often requiring renal replacement therapy; however, the outcomes following this are very good, supporting the early involvement of intensive care teams.

Carnitine palmitoyltransferase II deficiency with a focus on newborn screening

Carnitine palmitoyltransferase (CPT) II deficiency is one of the most common forms of mitochondrial fatty acid oxidation disorder. Its clinical phenotypes are classified into the muscle, severe infantile, and lethal neonatal forms. Among Caucasians, the muscle form predominates, and the c.338C > T (p.S113L) variant is detected in most cases, whereas among the Japanese, c.1148T > A (p.F383Y) is the variant allele occurring with the highest frequency and can apparently cause symptoms of the severe infantile form. Newborn screening (NBS) for this potentially fatal disease has not been established. We encountered an infantile case of CPT II deficiency not detected in NBS using C16 and C18:1 concentrations as indices, and therefore we adopted the (C16 + C18:1)/C2 ratio as an alternative primary index. As a result, the disease was diagnosed in nine of 31 NBS-positive subjects. The values for (C16 + C18:1)/C2 in the affected newborns partly overlapped with those in unaffected ones. Among several other indices proposed previously, C14/C3 has emerged as a more promising index. Based on these findings, nationwide NBS for CPT II deficiency using both (C16 + C18:1)/C2 and C14/C3 as indices was officially approved and started in April 2018. We diagnosed the disease in four young children presenting with symptoms of the muscle form, whose values for the new indices were not elevated. Although it is still difficult to detect all cases of the muscle form of CPT II deficiency in NBS, our system is expected to save many affected children in Japan with the severe infantile form predominating.

Mitochondrial carnitine palmitoyl transferase-II inactivity aggravates lipid accumulation in rat hepatocarcinogenesis

AIM

To investigate the dynamic alteration of mitochondrial carnitine palmitoyl transferase II (CPT-II) expression during malignant transformation of rat hepatocytes.

METHODS

Sprague-Dawley male rats were fed with normal, high fat (HF), and HF containing 2-fluorenylacetamide (2-FAA) diet, respectively. According to the Hematoxylin and Eosin staining of livers, rats were divided into control, fatty liver, degeneration, precancerous, and cancerous groups. Liver lipids were dyed with Oil Red O, CPT-II alterations were analyzed by immunohistochemistry, and compared with CPT-II specific concentration (μg/mg protein). Levels of total cholesterol (Tch), triglyceride (TG), and amino-transferases [alanine aminotransferase (ALT), aspartate aminotransferase (AST)] were determined by the routine methods.

RESULTS

After intake of HF and/or HF+2-FAA diets, the rat livers showed mass lipid accumulation. The lipid level in the control group was significantly lower than that in other groups. The changes of serum TG and Tch levels were abnormally increasing, 2-3 times more than those in the controls (P < 0.05). During the rat liver morphological changes from normal to cancer development process with hepatocyte injury, serum AST and ALT levels were significantly higher (4-8 times, P < 0.05) than those in the control group. The specific concentration of CPT-II in liver tissues progressively decreased during hepatocyte malignant transformation, with the lowest CPT-II levels in the cancer group than in any of the other groups (P < 0.05).

CONCLUSION

Low CPT-II expression might lead to abnormal hepatic lipid accumulation, which should promote the malignant transformation of hepatocytes.

Muscle Carnitine Palmitoyltransferase II Deficiency: A Review of Enzymatic Controversy and Clinical Features

CPT (carnitine palmitoyltransferase) II muscle deficiency is the most common form of muscle fatty acid metabolism disorders. In contrast to carnitine deficiency, it is clinically characterized by attacks of myalgia and rhabdomyolysis without persistent muscle weakness and lipid accumulation in muscle fibers. The biochemical consequences of the disease-causing mutations are still discussed controversially. CPT activity in muscles of patients with CPT II deficiency ranged from not detectable to reduced to normal. Based on the observation that in patients, total CPT is completely inhibited by malony-CoA, a deficiency of malonyl-CoA-insensitive CPT II has been suggested. In contrast, it has also been shown that in muscle CPT II deficiency, CPT II protein is present in normal concentrations with normal enzymatic activity. However, CPT II in patients is abnormally sensitive to inhibition by malonyl-CoA, Triton X-100 and fatty acid metabolites. A recent study on human recombinant CPT II enzymes (His₆-N-hCPT2 and His₆-N-hCPT2/S113L) revealed that the wild-type and the S113L variants showed the same enzymatic activity. However, the mutated enzyme showed an abnormal thermal destabilization at 40 and 45 °C and an abnormal sensitivity to inhibition by malony-CoA. The thermolability of the mutant enzyme might explain why symptoms in muscle CPT II deficiency mainly occur during prolonged exercise, infections and exposure to cold. In addition, the abnormally regulated enzyme might be mostly inhibited when the fatty acid metabolism is stressed.

Heat stroke with bimodal rhabdomyolysis: a case report and review of the literature

BACKGROUND

Severe heat stroke tends to be complicated with rhabdomyolysis, especially in patients with exertional heat stroke. Rhabdomyolysis usually occurs in the acute phase of heat stroke. We herein report a case of heat stroke in a patient who experienced bimodal rhabdomyolysis in the acute and recovery phases.

CASE PRESENTATION

A 34-year-old male patient was found lying unconscious on the road after participating in a half marathon in the spring. It was a sunny day with a maximum temperature of 24.2 °C. His medical and family history was unremarkable. Upon arrival, his Glasgow Coma Scale score was 10. However, the patient's marked restlessness and confusion returned. A sedative was administered and tracheal intubation was performed. On the second day of hospitalization, a blood analysis was compatible with a diagnosis of acute hepatic failure; thus, he received fresh frozen plasma and a platelet transfusion was performed, following plasma exchange and continuous hemodiafiltration. The patient's creatinine phosphokinesis (CPK) level increased to 8832 IU/L on the fifth day of hospitalization and then showed a tendency to transiently decrease. The patient was extubated on the eighth day of hospitalization after the improvement of his laboratory data. From the ninth day of hospitalization, gradual rehabilitation was initiated. However, he felt pain in both legs and his CPK level increased again. Despite the cessation of all drugs and rehabilitation, his CPK level increased to 105,945 IU/L on the 15th day of hospitalization. Fortunately, his CPK level decreased with a fluid infusion. The patient's rehabilitation was restarted after his CPK level fell to <10,000 IU/L. On the 31st day of hospitalization, his CK level decreased to 623 IU/L and he was discharged on foot. Later, a genetic analysis revealed that he had a thermolabile genetic phenotype of carnitine palmitoyltransferase II (CPT II).

CONCLUSIONS

Physicians should pay special attention to the stress of rehabilitation exercises, which may cause collapsed muscles that are injured by severe heat stroke to repeatedly flare up.