Naomi Brooks | Universidade Estadual Paulista "Júlio de Mesquita Filho" (original) (raw)

Papers by Naomi Brooks

Proceedings of the Nutrition Society

IntroductionSouth Africa (SA) is a developing country with an ageing population. Adequate nutriti... more IntroductionSouth Africa (SA) is a developing country with an ageing population. Adequate nutrition and physical activity (PA) protect against the loss of muscle mass and physical function, both of which are important components of sarcopenia. This study aimed to measure the prevalence of sarcopenia in older black SA women and investigate its associations with PA and protein intake.Materials and MethodsOlder black SA women (age, 68 (range; 60–85 years) n = 122) completed sociodemographic questionnaires, 24 h urine collection (estimate protein intake), venous blood (hs-C-reactive protein (hs-CRP) and ferritin), functional tests (grip strength, 3 m timed-up-and-go (TUG), 10 m walk test) and PA monitoring (activPAL). Dual-energy x-ray absorptiometry whole-body scans assessed fat and fat-free soft tissue mass (FFSTM).ResultsAccording to the European Working group on Sarcopenia in Older People (EWGSOP)2, 2.5% (n = 3) had confirmed sarcopenia of a low severity based on normal physical fun...

Physiology News

Idle J & Gonzalez F (2011). Metabolomics reveals attenuation of the SLC6A20 kidney transporter in... more Idle J & Gonzalez F (2011). Metabolomics reveals attenuation of the SLC6A20 kidney transporter in nonhuman primate and mouse models of type 2 diabetes mellitus.

Physiology News

Welcome to the Winter 2014 edition of Physiology News Introduction 05 Editorial News in brief 06 ... more Welcome to the Winter 2014 edition of Physiology News Introduction 05 Editorial News in brief 06 #Biobakes LifeSci TRC 07 Student-led 'Physiology Challenge' for Biology Week at the University of Leeds Physiology Feed 08 Policy Focus In depth 10 Cambridge physiology scores a century 12 Physiology on the go 14 A tribute to Bernhard Frankenhaeuser 1915-1994 Meetings & events 16 Forthcoming events Meeting notes: Obesity-a physiological perspective 17 Meeting notes: Special symposium for Dr Robert Banks 18 Young Life Scientists' Symposium 2014 19 Meeting notes: International lecture 2014 20 We know where we are going but how do we get there? Features Human metabolism and obesity: the influence of exercise Exercise: more than just a role in energy balance Sleep disturbance alters autonomic balance to the heart The mighty protein: Insulin-like growth factor type 1

American journal of physiology. Cell physiology, 2017

Mutations in the gene that encodes the principal l-carnitine transporter, OCTN2, can lead to a re... more Mutations in the gene that encodes the principal l-carnitine transporter, OCTN2, can lead to a reduced intracellular l-carnitine pool and the disease Primary Carnitine Deficiency. l-Carnitine supplementation is used therapeutically to increase intracellular l-carnitine. As AMPK and insulin regulate fat metabolism and substrate uptake, we hypothesized that AMPK-activating compounds and insulin would increase l-carnitine uptake in C2C12 myotubes. The cells express all three OCTN transporters at the mRNA level, and immunohistochemistry confirmed expression at the protein level. Contrary to our hypothesis, despite significant activation of PKB and 2DG uptake, insulin did not increase l-carnitine uptake at 100 nM. However, l-carnitine uptake was modestly increased at a dose of 150 nM insulin. A range of AMPK activators that increase intracellular calcium content [caffeine (10 mM, 5 mM, 1 mM, 0.5 mM), A23187 (10 μM)], inhibit mitochondrial function [sodium azide (75 μM), rotenone (1 μM), ...

Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2014

We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest.... more We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake needs to be maintained. This study aims to assess the potential for artificial gravity (AG) and exercise (EX) to mitigate loss of bone calcium during space flight. We performed two studies: (1) a 21-day bed rest (BR) study with subjects receiving 1 h/day AG (n = 8) or no AG (n = 7) and (2) a 28-day BR study with 1 h/day resistance EX (n = 10) or no EX (n = 3). In both studies, stable isotopes of Ca were administered orally and intravenously, at baseline and after 10 days of BR, and blood, urine, and feces were sampled for up to 14 days post dosing. Tracers were measured using thermal ionization mass spectrometry. Data were analyzed by compartmental modeling. Less Ca was absorbed during BR, ...

Frontiers in physiology, 2014

Maintenance of skeletal muscle is essential for health and survival. There are marked losses of s... more Maintenance of skeletal muscle is essential for health and survival. There are marked losses of skeletal muscle mass as well as strength and physiological function under conditions of low mechanical load, such as space flight, as well as ground based models such as bed rest, immobilization, disuse, and various animal models. Disuse atrophy is caused by mechanical unloading of muscle and this leads to reduced muscle mass without fiber attrition. Skeletal muscle stem cells (satellite cells) and myonuclei are integrally involved in skeletal muscle responses to environmental changes that induce atrophy. Myonuclear domain size is influenced differently in fast and slow twitch muscle, but also by different models of muscle wasting, a factor that is not yet understood. Although the myonuclear domain is 3-dimensional this is rarely considered. Apoptosis as a mechanism for myonuclear loss with atrophy is controversial, whereas cell death of satellite cells has not been considered. Molecular ...

Muscle & nerve, 2013

We investigated changes in satellite cell (SC) pool size after an acute bout of strenuous exercis... more We investigated changes in satellite cell (SC) pool size after an acute bout of strenuous exercise and evaluated the influence of baseline SC count and fiber type. Participants completed a downhill running (DHR) intervention (5 × 8 min, 2-min rest; 80% VO2max ; -10% gradient). Muscle biopsies were taken 7 days before VO₂max and 7-9 days after the DHR intervention. Delayed-onset muscle soreness (DOMS) and creatine kinase activity (CK) were measured on days 1, 2, 7, and 9 post-DHR. SCs were identified by Pax7 and laminin staining. Relative distribution of MHC isoforms was determined by electrophoresis. DOMS and CK peaked on day 1 post-DHR (P < 0.01). The SC pool increased (26%) after DHR (P = 0.005). SCs/total myonuclei after recovery correlated with baseline SCs (r = 0.979, P = 0.003) and VO₂max (r = 0.956, P = 0.011), whereas change in SC pool (Pax7(+) cells/total myonuclei: recovery minus baseline) tended to correlate with percent MHC II (r = 0.848; P = 0.06). Interindividual ph...

Scandinavian Journal of Medicine & Science in Sports, 2012

Satellite cells (SCs) are responsible for muscle repair following strenuous exercise or injury. S... more Satellite cells (SCs) are responsible for muscle repair following strenuous exercise or injury. SC responses to intervention have been studied, but most studies do not discuss or take into account the substantial variability in SC number among young individuals. We hypothesized that an active lifestyle reflected in higher VO(2max) may be associated with greater SC number. As training alters basal p38-mitogen-activated protein kinase (MAPK) activity, which is associated with SC proliferation, SC count may also correlate with this stress signaling kinase. Muscle biopsies from vastus lateralis of eight male participants were analyzed for fiber type, myogenin, and p38/phospho-p38 MAPK using SDS-PAGE and Western blotting. Immunofluorescence was used to detect Pax7(+) SCs. Two weeks following the biopsy, subjects underwent an incremental treadmill test to determine VO(2max) . A strong positive correlation (P = 0.0087) was found between the number of Pax7(+) nuclei and VO(2max) . Pax7(+) cell number correlated negatively with phospho-p38/p38 MAPK (P = 0.0006), but had no correlation with fiber type or myogenin. SC number is proportional to VO(2max) , and hence it can be postulated that higher levels of physical activity activate SC proliferation but not fusion, underlining the relevance of exercise in stimulating SC pool size even without injury.

Medicine & Science in Sports & Exercise, 2009

Medicine & Science in Sports & Exercise, 2009

Medicine & Science in Sports & Exercise, 2011

Medicine & Science in Sports & Exercise, 2008

Journal of Vascular Research, 2002

Iontophoretic assessment of skin microvascular function is complicated by the occurrence of elect... more Iontophoretic assessment of skin microvascular function is complicated by the occurrence of electrically induced hyperaemia, especially at the cathode. Studies were performed to identify means of reducing such effects. Skin vasodilator responses were measured using a laser Doppler imager that controlled iontophoretic current delivery. A novel feature involved monitoring voltage across the iontophoresis chambers. Comparison between responses to vehicle (distilled H(2)O), acetylcholine (ACh) and sodium nitroprusside (SNP) showed electrically induced hyperaemia at the cathode associated with the vehicle, whose time course overlapped with that of the SNP response. Voltage across the chambers containing drugs dissolved in H(2)O was significantly (p = 0.018, n = 7) lower than the voltage profile of H(2)O alone. H(2)O iontophoresis was associated with cathodal hyperaemic responses in most subjects, whereas a 0.5% NaCl vehicle produced lower voltages and eliminated this artefact. Voltage.time integral rather than charge was the prime determinant of electrically induced hyperaemic responses. No significant correlation was found between skin fold thickness and either calculated skin resistance (r(2) = 0.0002) or vascular response to ACh (r(2) = 0.13). Smaller chamber size led to higher voltages and greater electrically induced hyperaemic responses. These appear to be prostaglandin dependent as they were ablated by cyclooxygenase inhibition. Use of a low-resistance vehicle combined with larger chamber sizes and lower currents can prevent such artefacts, thereby increasing the robustness of this methodology for clinical assessment of endothelial function.

Journal of Applied Physiology, 2009

Journal of Applied Physiology, 2008

Spaceflight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (... more Spaceflight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (RT) and amino acid (AA) supplementation are potential countermeasures to minimize these losses. However, it is unknown if timing of supplementation with exercise can optimize benefits, particularly with energy deficit. We examined the effect of these countermeasures on body composition, strength, and insulin levels in 31 men (ages 31–55 yr) during BR (28 days) followed by active recovery (14 days). Subjects were randomly assigned to essential AA supplementation (AA group, n = 7); RT with AA given 3 h after training (RT group, n = 12); or RT with AA given 5 min before training (AART group, n = 12). Energy intake was reduced by 8 ± 6%. Midthigh muscle area declined with BR for the AA > RT > AART groups: −11%, −3%, −4% ( P = 0.05). Similarly, greatest losses in lower body muscle strength were seen in the AA group (−22%). These were attenuated in the exercising groups [RT (−8%) and AAR...

Acta Physiologica, 2009

In multinucleated skeletal muscle, a myonuclear domain is the region of cytoplasm governed by one... more In multinucleated skeletal muscle, a myonuclear domain is the region of cytoplasm governed by one nucleus, and myofibres are mosaics of overlapping myonuclear domains. Association of ageing and myonuclear domain is important in the understanding of sarcopenia and with prevention or combating age-related muscle declines. This study examined the effects of age, fibre type and muscle on nucleo-cytoplasmic (N/C) relationships as reflecting myonuclear domain size. Methods: The N/C was compared in fibre types of soleus and plantaris muscles from young (n = 6) and ageing (n = 8) male Fisher 344 rats. Results: There were no significant differences in fibre type composition or cross-sectional area of the soleus across ages. The old soleus had significantly more myonuclei, resulting in a significantly smaller myonuclear domain size. The plantaris muscle showed a higher percentage of slow fibres in old compared with young fibres. There were no differences in the number of myonuclei or in myonuclear domain size between young and older animals. Conclusion: We found muscle-specific differences in the effects of ageing on myonuclear domain, possibly as a result of reduced efficiency of the myonuclei in the slow muscles.

Proceedings of the Nutrition Society

IntroductionSouth Africa (SA) is a developing country with an ageing population. Adequate nutriti... more IntroductionSouth Africa (SA) is a developing country with an ageing population. Adequate nutrition and physical activity (PA) protect against the loss of muscle mass and physical function, both of which are important components of sarcopenia. This study aimed to measure the prevalence of sarcopenia in older black SA women and investigate its associations with PA and protein intake.Materials and MethodsOlder black SA women (age, 68 (range; 60–85 years) n = 122) completed sociodemographic questionnaires, 24 h urine collection (estimate protein intake), venous blood (hs-C-reactive protein (hs-CRP) and ferritin), functional tests (grip strength, 3 m timed-up-and-go (TUG), 10 m walk test) and PA monitoring (activPAL). Dual-energy x-ray absorptiometry whole-body scans assessed fat and fat-free soft tissue mass (FFSTM).ResultsAccording to the European Working group on Sarcopenia in Older People (EWGSOP)2, 2.5% (n = 3) had confirmed sarcopenia of a low severity based on normal physical fun...

Physiology News

Idle J & Gonzalez F (2011). Metabolomics reveals attenuation of the SLC6A20 kidney transporter in... more Idle J & Gonzalez F (2011). Metabolomics reveals attenuation of the SLC6A20 kidney transporter in nonhuman primate and mouse models of type 2 diabetes mellitus.

Physiology News

Welcome to the Winter 2014 edition of Physiology News Introduction 05 Editorial News in brief 06 ... more Welcome to the Winter 2014 edition of Physiology News Introduction 05 Editorial News in brief 06 #Biobakes LifeSci TRC 07 Student-led 'Physiology Challenge' for Biology Week at the University of Leeds Physiology Feed 08 Policy Focus In depth 10 Cambridge physiology scores a century 12 Physiology on the go 14 A tribute to Bernhard Frankenhaeuser 1915-1994 Meetings & events 16 Forthcoming events Meeting notes: Obesity-a physiological perspective 17 Meeting notes: Special symposium for Dr Robert Banks 18 Young Life Scientists' Symposium 2014 19 Meeting notes: International lecture 2014 20 We know where we are going but how do we get there? Features Human metabolism and obesity: the influence of exercise Exercise: more than just a role in energy balance Sleep disturbance alters autonomic balance to the heart The mighty protein: Insulin-like growth factor type 1

American journal of physiology. Cell physiology, 2017

Mutations in the gene that encodes the principal l-carnitine transporter, OCTN2, can lead to a re... more Mutations in the gene that encodes the principal l-carnitine transporter, OCTN2, can lead to a reduced intracellular l-carnitine pool and the disease Primary Carnitine Deficiency. l-Carnitine supplementation is used therapeutically to increase intracellular l-carnitine. As AMPK and insulin regulate fat metabolism and substrate uptake, we hypothesized that AMPK-activating compounds and insulin would increase l-carnitine uptake in C2C12 myotubes. The cells express all three OCTN transporters at the mRNA level, and immunohistochemistry confirmed expression at the protein level. Contrary to our hypothesis, despite significant activation of PKB and 2DG uptake, insulin did not increase l-carnitine uptake at 100 nM. However, l-carnitine uptake was modestly increased at a dose of 150 nM insulin. A range of AMPK activators that increase intracellular calcium content [caffeine (10 mM, 5 mM, 1 mM, 0.5 mM), A23187 (10 μM)], inhibit mitochondrial function [sodium azide (75 μM), rotenone (1 μM), ...

Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA, 2014

We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest.... more We assessed the potential for countermeasures to lessen the loss of bone calcium during bed rest. Subjects ingested less calcium during bed rest, and with artificial gravity, they also absorbed less calcium. With exercise, they excreted less calcium. To retain bone during bed rest, calcium intake needs to be maintained. This study aims to assess the potential for artificial gravity (AG) and exercise (EX) to mitigate loss of bone calcium during space flight. We performed two studies: (1) a 21-day bed rest (BR) study with subjects receiving 1 h/day AG (n = 8) or no AG (n = 7) and (2) a 28-day BR study with 1 h/day resistance EX (n = 10) or no EX (n = 3). In both studies, stable isotopes of Ca were administered orally and intravenously, at baseline and after 10 days of BR, and blood, urine, and feces were sampled for up to 14 days post dosing. Tracers were measured using thermal ionization mass spectrometry. Data were analyzed by compartmental modeling. Less Ca was absorbed during BR, ...

Frontiers in physiology, 2014

Maintenance of skeletal muscle is essential for health and survival. There are marked losses of s... more Maintenance of skeletal muscle is essential for health and survival. There are marked losses of skeletal muscle mass as well as strength and physiological function under conditions of low mechanical load, such as space flight, as well as ground based models such as bed rest, immobilization, disuse, and various animal models. Disuse atrophy is caused by mechanical unloading of muscle and this leads to reduced muscle mass without fiber attrition. Skeletal muscle stem cells (satellite cells) and myonuclei are integrally involved in skeletal muscle responses to environmental changes that induce atrophy. Myonuclear domain size is influenced differently in fast and slow twitch muscle, but also by different models of muscle wasting, a factor that is not yet understood. Although the myonuclear domain is 3-dimensional this is rarely considered. Apoptosis as a mechanism for myonuclear loss with atrophy is controversial, whereas cell death of satellite cells has not been considered. Molecular ...

Muscle & nerve, 2013

We investigated changes in satellite cell (SC) pool size after an acute bout of strenuous exercis... more We investigated changes in satellite cell (SC) pool size after an acute bout of strenuous exercise and evaluated the influence of baseline SC count and fiber type. Participants completed a downhill running (DHR) intervention (5 × 8 min, 2-min rest; 80% VO2max ; -10% gradient). Muscle biopsies were taken 7 days before VO₂max and 7-9 days after the DHR intervention. Delayed-onset muscle soreness (DOMS) and creatine kinase activity (CK) were measured on days 1, 2, 7, and 9 post-DHR. SCs were identified by Pax7 and laminin staining. Relative distribution of MHC isoforms was determined by electrophoresis. DOMS and CK peaked on day 1 post-DHR (P < 0.01). The SC pool increased (26%) after DHR (P = 0.005). SCs/total myonuclei after recovery correlated with baseline SCs (r = 0.979, P = 0.003) and VO₂max (r = 0.956, P = 0.011), whereas change in SC pool (Pax7(+) cells/total myonuclei: recovery minus baseline) tended to correlate with percent MHC II (r = 0.848; P = 0.06). Interindividual ph...

Scandinavian Journal of Medicine & Science in Sports, 2012

Satellite cells (SCs) are responsible for muscle repair following strenuous exercise or injury. S... more Satellite cells (SCs) are responsible for muscle repair following strenuous exercise or injury. SC responses to intervention have been studied, but most studies do not discuss or take into account the substantial variability in SC number among young individuals. We hypothesized that an active lifestyle reflected in higher VO(2max) may be associated with greater SC number. As training alters basal p38-mitogen-activated protein kinase (MAPK) activity, which is associated with SC proliferation, SC count may also correlate with this stress signaling kinase. Muscle biopsies from vastus lateralis of eight male participants were analyzed for fiber type, myogenin, and p38/phospho-p38 MAPK using SDS-PAGE and Western blotting. Immunofluorescence was used to detect Pax7(+) SCs. Two weeks following the biopsy, subjects underwent an incremental treadmill test to determine VO(2max) . A strong positive correlation (P = 0.0087) was found between the number of Pax7(+) nuclei and VO(2max) . Pax7(+) cell number correlated negatively with phospho-p38/p38 MAPK (P = 0.0006), but had no correlation with fiber type or myogenin. SC number is proportional to VO(2max) , and hence it can be postulated that higher levels of physical activity activate SC proliferation but not fusion, underlining the relevance of exercise in stimulating SC pool size even without injury.

Medicine & Science in Sports & Exercise, 2009

Medicine & Science in Sports & Exercise, 2009

Medicine & Science in Sports & Exercise, 2011

Medicine & Science in Sports & Exercise, 2008

Journal of Vascular Research, 2002

Iontophoretic assessment of skin microvascular function is complicated by the occurrence of elect... more Iontophoretic assessment of skin microvascular function is complicated by the occurrence of electrically induced hyperaemia, especially at the cathode. Studies were performed to identify means of reducing such effects. Skin vasodilator responses were measured using a laser Doppler imager that controlled iontophoretic current delivery. A novel feature involved monitoring voltage across the iontophoresis chambers. Comparison between responses to vehicle (distilled H(2)O), acetylcholine (ACh) and sodium nitroprusside (SNP) showed electrically induced hyperaemia at the cathode associated with the vehicle, whose time course overlapped with that of the SNP response. Voltage across the chambers containing drugs dissolved in H(2)O was significantly (p = 0.018, n = 7) lower than the voltage profile of H(2)O alone. H(2)O iontophoresis was associated with cathodal hyperaemic responses in most subjects, whereas a 0.5% NaCl vehicle produced lower voltages and eliminated this artefact. Voltage.time integral rather than charge was the prime determinant of electrically induced hyperaemic responses. No significant correlation was found between skin fold thickness and either calculated skin resistance (r(2) = 0.0002) or vascular response to ACh (r(2) = 0.13). Smaller chamber size led to higher voltages and greater electrically induced hyperaemic responses. These appear to be prostaglandin dependent as they were ablated by cyclooxygenase inhibition. Use of a low-resistance vehicle combined with larger chamber sizes and lower currents can prevent such artefacts, thereby increasing the robustness of this methodology for clinical assessment of endothelial function.

Journal of Applied Physiology, 2009

Journal of Applied Physiology, 2008

Spaceflight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (... more Spaceflight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (RT) and amino acid (AA) supplementation are potential countermeasures to minimize these losses. However, it is unknown if timing of supplementation with exercise can optimize benefits, particularly with energy deficit. We examined the effect of these countermeasures on body composition, strength, and insulin levels in 31 men (ages 31–55 yr) during BR (28 days) followed by active recovery (14 days). Subjects were randomly assigned to essential AA supplementation (AA group, n = 7); RT with AA given 3 h after training (RT group, n = 12); or RT with AA given 5 min before training (AART group, n = 12). Energy intake was reduced by 8 ± 6%. Midthigh muscle area declined with BR for the AA > RT > AART groups: −11%, −3%, −4% ( P = 0.05). Similarly, greatest losses in lower body muscle strength were seen in the AA group (−22%). These were attenuated in the exercising groups [RT (−8%) and AAR...

Acta Physiologica, 2009

In multinucleated skeletal muscle, a myonuclear domain is the region of cytoplasm governed by one... more In multinucleated skeletal muscle, a myonuclear domain is the region of cytoplasm governed by one nucleus, and myofibres are mosaics of overlapping myonuclear domains. Association of ageing and myonuclear domain is important in the understanding of sarcopenia and with prevention or combating age-related muscle declines. This study examined the effects of age, fibre type and muscle on nucleo-cytoplasmic (N/C) relationships as reflecting myonuclear domain size. Methods: The N/C was compared in fibre types of soleus and plantaris muscles from young (n = 6) and ageing (n = 8) male Fisher 344 rats. Results: There were no significant differences in fibre type composition or cross-sectional area of the soleus across ages. The old soleus had significantly more myonuclei, resulting in a significantly smaller myonuclear domain size. The plantaris muscle showed a higher percentage of slow fibres in old compared with young fibres. There were no differences in the number of myonuclei or in myonuclear domain size between young and older animals. Conclusion: We found muscle-specific differences in the effects of ageing on myonuclear domain, possibly as a result of reduced efficiency of the myonuclei in the slow muscles.