Introduction of adult cats to indirect calorimetry respiration chambers causes increased energy expenditure and respiratory quotient that decrease following acclimation

OBJECTIVE To replicate a previously defined behavioral procedure to acclimate adult cats to temporary restriction in indirect calorimetry chambers and measure energy expenditure and respiratory quotient changes during acclimation. ANIMALS 8 healthy adult cats (4 spayed females, and 4 neutered males; mean ± SEM age, 2.5 ± 1.5 years; mean body weight, 4.8 ± 1.8 kg). PROCEDURES Cats underwent a 13-week incremental acclimation procedure whereby cats were acclimated to the chambers in their home environment (weeks 1 to 3), to the study room (weeks 4 to 6), and to increasing lengths of restriction within their home environment (weeks 7 to 8) and the chambers (weeks 9 to 13). Cat stress score, respiratory rate, fearfulness (assessed with a novel object test), energy expenditure, and respiratory quotient were measured. Data were analyzed by use of a repeated-measures mixed model. RESULTS Stress, based on cat stress scores, fearfulness, and respiration, peaked at weeks 4, 9, and 10 but returned to baseline levels by week 11. Energy expenditure and respiratory quotient peaked at weeks 10 and 11, respectively, but were reduced significantly by weeks 11 and 13, respectively. All cats returned to baseline by the end of the study and were deemed fully acclimated. CLINICAL RELEVANCE Changes in perceived stress level, energy expenditure, and respiratory quotient at various stages of the acclimation procedure suggest that stress should be considered a significant variable in energy balance measurements when indirect calorimetry is used in cats. An incremental acclimation procedure should therefore be used to prepare cats for the temporary space restriction necessary for indirect calorimetry studies.

Studi Respirasi Belimbing Wuluh Menggunakan Modifikasi Udara Pasif

Penyimpanan bahan pangan pertanian secara modifikasi udara pasif cukup populer sebagai metode penyimpanan buah dan sayur segar. Modifikasi udara pasif menghasilkan komposisi alami udara di dalam ruangan karena adanya aktivitas respirasi aerobik yang berdampak kepada kematangan dan umur simpan. Pengukuran data-data aktivitas respirasi belimbing wuluh secara aerobik dapat digunakan untuk menghitung laju respirasi dan penggunaan substrat. Perubahan metabolisme belimbing wuluh (Averrhoa Bilimbi Linn) setelah panen di ukur aktivitas repirasi aerobiknya di dalam toples kedap udara selama 24 jam menggunakan sensor gas oksigen berbasis zirconium dan infrared. Pelepasan panas dan uap air di rekam menggunakan logger suhu dan kelembaban. Hasil penelitian menunjukkan bahwa kecepatan respirasi paling cepat pada periode 1 jam penyimpanan dengan nilai laju repirasi oksigen (RO2) 28,60 ml [O2] kg-1 jam-1 dan laju respirasi karbondioksida (RCO2) 56,64 ml [CO2] kg-1 jam-1. Nilai respiratory quotient (RQ) diatas 1,0 menunjukkan respirasi menggunakan substrat asam organik. Substrat respirasi terhitung sebagai total asam diperoleh laju rerata konsumsi 0,03 mg equivalen/100 g dan susut bobot rata-rata 0,04%. Hasil uji empiris penyimpanan belimbing wuluh sampai periode 24 jam masuk dalam kategori sour-unripe dan menggunakan regresi eksponansial dapat diperoleh perubahan kematangan belimbing wuluh menjadi kategori sour-ripe akan didapatkan setelah periode penyimpanan mencapai 37 jam.

Free fatty acids, glicentin and glucose-dependent insulinotropic polypeptide as potential major determinants of fasting substrate oxidation

The selection of carbohydrates or fat to generate intracellular energy is thought to be crucial for long-term metabolic health. While most studies assess fuel selection after a metabolic challenge, the determinants of substrate oxidation in the fasted state remain largely unexplored. We therefore assessed the respiratory quotient by indirect calorimetry as a read-out for substrate oxidation following an overnight fast. This cross-sectional analysis consisted of 192 (92 women, 100 men) either lean or obese participants. Following an overnight fast, the respiratory quotient (RQ) was assessed, after which a 5-point 75-g oral glucose tolerance test was performed. Unlike glucose and insulin, fasting free fatty acids (FFA) correlated negatively with fasting RQ (p < 0.0001). Participants with high levels of the ketone body β-hydroxybutyric acid had significantly lower RQ values. Fasting levels of glucose-dependent insulinotropic polypeptide (GIP) and glicentin were positively associated with fasting RQ (all p ≤ 0.03), whereas GLP-1 showed no significant association. Neither BMI, nor total body fat, nor body fat distribution correlated with fasting RQ. No relationship between the RQ and diabetes or the metabolic syndrome could be observed. In the fasting state, FFA concentrations were strongly linked to the preferentially oxidized substrate. Our data did not indicate any relationship between fasting substrate oxidation and metabolic diseases, including obesity, diabetes, and the metabolic syndrome. Since glicentin and GIP are linked to fuel selection in the fasting state, novel therapeutic approaches that target these hormones may have the potential to modulate substrate oxidation.

Effect of Dietary Strategies on Respiratory Quotient and Its Association with Clinical Parameters and Organ Fat Loss: A Randomized Controlled Trial

The relation between changes in respiratory quotient (RQ) following dietary interventions and clinical parameters and body fat pools remains unknown. In this randomized controlled trial, participants with moderate abdominal obesity or/and dyslipidemia (n = 159) were randomly assigned to a Mediterranean/low carbohydrate (MED/LC, n = 80) or a low fat (LF, n = 79) isocaloric weight loss diet and completed a metabolic assessment. Changes in RQ (measured by indirect calorimeter), adipose-tissue pools (MRI), and clinical measurements were assessed at baseline and after 6 months of intervention. An elevated RQ at baseline was significantly associated with increased visceral adipose tissue, hepatic fat, higher levels of insulin and homeostatic insulin resistance. After 6 months, body weight had decreased similarly between the diet groups (−6 ± 6 kg). However, the MED/LC diet, which greatly improved metabolic health, decreased RQ significantly more than the LF diet (−0.022 ± 0.007 vs. −0.002 ± 0.008, p = 0.005). Total cholesterol and diastolic blood pressure were independently associated with RQ changes (p = 0.045). RQ was positively associated with increased superficial subcutaneous-adipose-tissue but decreased renal sinus, pancreatic, and intramuscular fats after adjusting for confounders. Fasting RQ may reflect differences in metabolic characteristics between subjects affecting their potential individual response to the diet.

Performance of Fungal Growth Through Integrated Gompertz Model and Respiratory Quotient by Solid State Fermentation in Multi-Layer Squared Tray Solid State Bioreactor with Aeration Strategies

A newly designed, laboratory-scaled and multi-layer squared tray solid state bioreactor (SSB), was developed and successfully operated in solid state fermentation (SSF) conditions. The bioreactor was divided into eight layers of squared perforated trays. Wheat bran was used as a solid substrate for the growth of Aspergillus awamori and Aspergillus oryzae. The SSB was equipped with an oxygen (O2)/carbon dioxide (CO2) gas analyser and a thermocouple. Continuous on-line monitoring of fungal growth could be performed by indirect methods that measure O2 consumed, production of CO2 and metabolic heat. The advantage of using this method is that there are no tedious and time-consuming sampling processes. The evolution of CO2, which represents an accumulation term, was integrated with time and fitted to the Gompertz model in a log-like equation. The Gompertz model generated values that may be used to stimulate and verify the experimental data. Results strongly suggest that the evolved and accumulated CO2, excellently described fungal growth. Simulated results agreed with experimental results. The respiratory quotient (RQ), which is the ratio of CO2 evolution rate (CER) to O2 uptake rate (OUR), was determined by the gas balance method. CER and OUR confirmed that measurements correlated to fungal activity. Each RQ values can explain the differences of each SFF process carried out. Yet, heat evolved by fungal activity also described fungal growth. The current findings is an excellent pre-liminary experimental work, evidencing that multi-layer squared tray SSB with forced moistened aeration present a promising alternative of instrumented bioreactors for SSF processes.

A method for measuring the molecular ratio of inhalation to exhalation and effect of inspired oxygen levels on oxygen consumption

Using a new method for measuring the molecular ratio (R) of inhalation to exhalation, we investigated the effect of high fraction of inspired oxygen (FIO2) on oxygen consumption (VO2), carbon dioxide generation (VCO2), and respiratory quotient (RQ) in mechanically ventilated rats. Twelve rats were equally assigned into two groups by anesthetics: intravenous midazolam/fentanyl vs. inhaled isoflurane. R, VO2, VCO2, and RQ were measured at FIO2 0.3 or 1.0. R error was ± 0.003. R was 1.0099 ± 0.0023 with isoflurane and 1.0074 ± 0.0018 with midazolam/fentanyl. R was 1.0081 ± 0.0017 at an FIO2 of 0.3 and 1.0092 ± 0.0029 at an FIO2 of 1.0. There were no differences in VCO2 among the groups. VO2 increased at FIO2 1.0, which was more notable when midazolam/fentanyl was used (isoflurane-FIO2 0.3: 15.4 ± 1.1; isoflurane-FIO2 1.0: 17.2 ± 1.8; midazolam/fentanyl-FIO2 0.3: 15.4 ± 1.1; midazolam/fentanyl-FIO2 1.0: 21.0 ± 2.2 mL/kg/min at STP). The RQ was lower at FIO2 1.0 than FIO2 0.3 (isoflurane-FIO2 0.3: 0.80 ± 0.07; isoflurane-FIO2 1.0: 0.71 ± 0.05; midazolam/fentanyl-FIO2 0.3: 0.79 ± 0.03; midazolam/fentanyl-FIO2 1.0: 0.59 ± 0.04). R was not affected by either anesthetics or FIO2. Inspired 100% O2 increased VO2 and decreased RQ, which might be more remarkable when midazolam/fentanyl was used.