Carnitine levels in skeletal muscle of malnourished patients before and after total parenteral nutrition

Salivary metabolites as potential predictive biomarkers for lung surgery complications: a retrospective cross-sectional study

PURPOSE

Saliva is often used as a tool for identifying systemic diseases because of the noninvasive nature of its collection. Moreover, salivary metabolites can be potential predictive factors for postoperative survival. We conducted the present study to establish whether salivary metabolites can function as predictive biomarkers for lung surgery complications.

METHODS

Unstimulated salivary samples were collected from 412 patients before lung surgery. Salivary metabolites were analyzed comprehensively by capillary electrophoresis mass spectrometry. Clinical data with the discriminatory ability of biomarkers were assessed to predict lung surgery complications using multivariate logistic regression analysis. The primary endpoint was the risk factors for postoperative complications of Clavien-Dindo grade ≥ III.

RESULTS

Postoperative complications of Clavien-Dindo grade ≥ III developed in 36 patients (8.7%). There was no postoperative 30-day mortality. Male sex (odds ratio [OR], 3.852; 95% confidence interval CI 1.455-10.199; p = 0.007) and salivary gamma-butyrobetaine (OR, 0.809; 95% CI 0.694-0.943; p = 0.007) were identified as significant risk factors for postoperative complications of Clavien-Dindo grade ≥ III.

CONCLUSION

Salivary metabolites are potential noninvasive biomarkers for predicting postoperative complications of lung surgery.

Oxygen utilisation in patients on prolonged parenteral nutrition; a case-controlled study

BACKGROUND

Parenteral nutrition (PN) deficient in mitochondrial substrates and thiamine may lead to acidosis. This, combined with fatigue seen in patients with intestinal failure (IF), may suggest suboptimal oxidative metabolism. We therefore studied oxygen utilisation in otherwise apparently well-nourished individuals with intestinal failure receiving long term PN.

METHODS

This was a retrospective analysis conducted in a tertiary IF institution, from 2010 to 2019, comparing treadmill/bicycle cardiopulmonary exercise test (CPET) derived variables including peak oxygen consumption (VO_{2 peak}), anaerobic threshold (AT) and ventilatory efficiency (minute ventilation (VE)/CO₂ output (VCO₂) of patients with IF (cases) to those without (controls), matched in a 1:2 ratio for age ( ± 3 years), gender, use of beta-blockers and physiology parameters of p-POSSUM score ( ± 5). All subjects were free of sepsis and metastatic malignancy. Mann-Whitney or Student's t-test for continuous and Fisher's exact or chi-squared test for categorical variables were used as appropriate. Data shown represent mean or median values.

RESULTS

Participants (31 cases, 62 controls) were comparable in age (65.4 vs. 65.3, p = 0.98); p-POSSUM parameters (18.0 vs. 17.0, p = 0.45); gender (p = 1.00); smoking status (p = 0.52); use of beta-blockers (p = 1.00) and ≤10 mg/day of oral steroids (p = 0.34). Participants had been on PN for 11.0 (6.0-24.0) months and were adequately nourished (requirements 27.6 kcal/kg/day, replacement 23.5 kcal/kg/day). No differences were found between VO_{2 peak} (15.2 vs. 14.6 ml/kg/min, p = 0.96), AT (10.4 vs. 11.0 ml/kg/min, p = 0.44) and VE/VCO₂ (33.0 vs. 33.0, p = 0.96) of the examined groups.

CONCLUSION

Patients with intestinal failure receiving PN who are apparently well-nourished also appear to have normal oxygen utilisation, suggesting alternative causes for fatigue. More studies will be required to determine whether CPET could reliably be used to assess perioperative risk in this group of patients.

The correlation of the serum level of L-carnitine with disease severity in patients with Amyotrophic lateral sclerosis

BACKGROUND

The relationship between reserve of L-carnitine and severity in patients with Amyotrophic lateral sclerosis (ALS) is not studied sufficiently. We decided to measure the serum levels of L-carnitine in patients and the relationship with ALS severity.

METHOD

This cross-sectional study evaluated the serum levels of L-carnitine in 30 patients with ALS (total-case) divided into two groups included 15 patients in the Oral-Fed (OF) group and 15 patients in the Enteral-Fed (EF) group, compared with 15 healthy people matched in age and sex in the control group. We measured the body mass index (BMI), daily intake of L-carnitine, amyotrophic lateral sclerosis functional rating scale (ALSFRS), and serum L-carnitine level in all participants and compared among groups.

RESULTS

Serum L-carnitine (p < 0.001) and BMI (p = 0.03) were significantly lower in the total-case group compared to the control group. Alternatively, the serum level of L-carnitine (p = 0.001), ALSFRS (p < 0.001), BMI (p = 0.007), and dietary L-carnitine intake (p = 0.002) were significantly higher in OF group compared with EF. Higher serum L-carnitine levels were associated with a higher score of ALSFRS (β = 0.46, P = 0.01) in the total-case group.

CONCLUSION

Our study's results showed that serum levels of L-carnitine were lower in patients with ALS in comparison to healthy people. Also, the lower serum level of L-carnitine was associated with the higher severity of the disease.

The effect of carnitine supplemented total parenteral nutrition on lipid, energy and nitrogen metabolism in severely ill patients

To analyse the effects of L-carnitine supplemented TPN on lipid, energy and nitrogen metabolism, 16 severely injured patients were studied during the first 8 days after trauma. An L-carnitine solution (3g = 18.6mmol) was added to the fat emulsion and infused over 16h in a blind randomised fashion to half of the patients. Plasma triglyceride, free fatty acid and 3-OH-butyrate concentrations increased during the fat infusion, and fell to pre-infusion concentrations within 24h. There were no differences in plasma levels before, during or after infusion between the groups. ATP and phosphocreatine in muscle tissue were not influenced by carnitine supplementation. Glycogen, however, remained unchanged in the carnitine group and fell in the non-carnitine group. A cumulative N-balance measured from day 2 to day 8 was equally negative in both groups. Plasma carnitine levels were significantly higher in the supplemented group from day 3. The mean daily urinary carnitine excretion was increased 15-fold in the supplemented group. Muscle carnitine, however, remained unchanged in both groups and did not differ between them. The present results do not demonstrate any beneficial effects of parenterally administered L-carnitine on lipid, energy or nitrogen metabolism except for maintaining normal muscle glycogen levels in critically ill patients receiving TPN during the early phase after trauma.

Muscle carnitine pools in cancer patients

Muscle and plasma concentrations of free and acylated carnitine (short-chain acylcarnitine and long-chain acylcarnitine) were determined by employing an optimized radiochemical-enzymatic assay in 14 healthy volunteers and in 10 patients with oesophageal carcinoma prior to elective operation. No significant correlations between total carnitine and its subfractions in muscle and plasma were observed and no sex differences were apparent. The estimated total carnitine pool in the patients (75.0 +/- 27 mmol) was significantly reduced compared to controls (130 +/- 24.3 mmol). The reduction was still present when expressed per kg muscle tissue (3.5 +/- 1.0 mmol versus 4.5 +/- 0.7 mmol) in order to consider age related decreased muscle mass in the patients. The muscular ratio of acylcarnitines to free carnitine was higher in the patients (0.23 +/- 0.10) than in healthy subjects (0.15 +/- 0.07), whereas the corresponding plasma quotient in the patients (0.22 +/- 0.09) was lowered compared to controls (0.30 +/- 0.10), indicating that instead of glucose, oxidation of fatty acids can be maintained, resulting in a preservation of the glycogen stores and thus an energy-conserving metabolic adaptation as a response to prolonged energy deficit.

[Effect of L-carnitine supplemented total parenteral nutrition on postoperative lipid and nitrogen utilization]

During episodes of trauma carnitine-free total parenteral nutrition (TPN) may result in a reduction of the total body carnitine pool, leading to a diminished rate of fat oxidation. Sixteen patients undergoing esophagectomy were equally and randomly divided and received isonitrogenous (0.2 gN/kg.day) and isocaloric (35 kcal/kg.day TPN over 11 days without and with L-carnitine supplementation (12 mg/kg.day). Compared with healthy controls, the total body carnitine pool was significantly reduced in both groups prior to the operation. Without supplementation carnitine concentrations were maintained, while daily provision of carnitine resulted in an elevation of total carnitine mainly due to an increase of the free fraction. Without supplementation the cumulative urinary carnitine losses were 11.5 +/- 6.3 mmol corresponding to 15.5% +/- 8.5% of the estimated total body carnitine pool. Patients receiving carnitine revealed a positive carnitine balance in the immediate postoperative phase, 11.1% +/- 19.0% of the infused carnitine being retained. After 11 days of treatment comparable values for respiratory quotient, plasma triglycerides, free fatty acids, ketone bodies, and cumulative nitrogen balance were observed. It is concluded that in the patient population studied here carnitine supplementation during postoperative TPN did not improve fat oxidation or nitrogen balance.