Implications of reactive oxygen species in lung cancer and exploiting it for therapeutic interventions

Lung cancer is the second (11.4%) most commonly diagnosed cancer and the first (18%) to cause cancer-related deaths worldwide. The incidence of lung cancer varies significantly among men, women, and high and low-middle-income countries. Air pollution, inhalable agents, and tobacco smoking are a few of the critical factors that determine lung cancer incidence and mortality worldwide. Reactive oxygen species are known factors of lung carcinogenesis resulting from the xenobiotics and their mechanistic paths are under critical investigation. Reactive oxygen species exhibit dual roles in cells, as a tumorigenic and anti-proliferative factor, depending on spatiotemporal context. During the precancerous state, ROS promotes cancer origination through oxidative stress and base-pair substitution mutations in pro-oncogenes and tumor suppressor genes. At later stages of tumor progression, they help the cancer cells in invasion, and metastases by activating the NF-kB and MAPK pathways. However, at advanced stages, when ROS exceeds the threshold, it promotes cell cycle arrest and induces apoptosis in cancer cells. ROS activates extrinsic apoptosis through death receptors and intrinsic apoptosis through mitochondrial pathways. Moreover, ROS upregulates the expression of beclin-1 which is a critical component to initiate autophagy, another form of programmed cell death. ROS is additionally involved in an intermediatory step in necroptosis, which catalyzes and accelerates this form of cell death. Various therapeutic interventions have been attempted to exploit this cytotoxic potential of ROS to treat different cancers. Growing body of evidence suggests that ROS is also associated with chemoresistance and cancer cell immunity. Considering the multiple roles of ROS, this review highlights the exploitation of ROS for various therapeutic interventions. However, there are still gaps in the literature on the dual roles of ROS and the involvement of ROS in cancer cell immunity and therapy resistance.

Fluid and electrolyte management in preterm infants with patent ductus arteriosus

Optimal fluid management of preterm babies with suspected or confirmed diagnosis of patent ductus arteriosus (PDA) is frequently challenging for neonatal care physician because of paucity of clinical trials. There is wide variation in practice across neonatal units, resulting in significant impact on outcomes in Extremely Low Birth Weight (ELBW) babies with hemodynamically significant PDA. A delicate balance is required in fluid management to reduce mortality and morbidity in this population. The purpose of this review is to lay out the current understanding about fluid and electrolyte management in ELBW babies with hemodynamically significant PDA and highlight areas for future research.

Adverse childhood experiences and substance misuse in young people in India: results from the multisite cVEDA cohort

BACKGROUND

Adverse childhood experiences (ACEs) increases vulnerability to externalising disorders such as substance misuse. The study aims to determine the prevalence of ACEs and its association with substance misuse.

METHODS

Data from the Consortium on Vulnerability to Externalising Disorders and Addictions (cVEDA) in India was used (n = 9010). ACEs were evaluated using the World Health Organisation (WHO) Adverse Childhood Experiences International Questionnaire whilst substance misuse was assessed using the WHO Alcohol, Smoking and Substance Involvement Screening Test. A random-effects, two-stage individual patient data meta-analysis explained the associations between ACEs and substance misuse with adjustments for confounders such as sex and family structure.

RESULTS

1 in 2 participants reported child maltreatment ACEs and family level ACEs. Except for sexual abuse, males report more of every individual childhood adversity and are more likely to report misusing substances compared with females (87.3% vs. 12.7%). In adolescents, family level ACEs (adj OR 4.2, 95% CI 1.5-11.7) and collective level ACEs (adj OR 6.6, 95% CI 1.4-31.1) show associations with substance misuse whilst in young adults, child level ACEs such as maltreatment show similar strong associations (adj OR 2.0, 95% CI 1.1-3.5).

CONCLUSION

ACEs such as abuse and domestic violence are strongly associated with substance misuse, most commonly tobacco, in adolescent and young adult males in India. The results suggest enhancing current ACE resilience programmes and 'trauma-informed' approaches to tackling longer-term impact of ACEs in India.

FUNDING

Newton Bhabha Grant jointly funded by the Medical Research Council, UK (MR/N000390/1) and the Indian Council of Medical Research (ICMR/MRC-UK/3/M/2015-NCD-I).

Cognitive function and behavioral problems in children born to mothers with preeclampsia: an Indian study

Studies from high-income countries report associations of preeclampsia (PE) with reduced cognitive function and adverse behavioural outcomes in children. We examined these associations in Indian children aged 5-7 years. Children of mothers with PE (n=74) and without PE (non-PE; n=234) were recruited at delivery at Bharati Hospital, Pune, India. The cognitive performance was assessed using 3 core tests from the Kaufman Assessment Battery and additional tests including Verbal fluency, Kohs block design, and Coding A (from Wechsler Intelligence Scale for Children). The parent-reported Strengths and Difficulties Questionnaire (SDQ) was used to assess children's behavioral characteristics. Scores were compared between children from PE and non-PE groups, and associations analyzed further using regression models, adjusted for potential confounders. After adjusting for age, sex, socio-economic status and maternal education, children of PE mothers had lower Kohs block design scores (adjusted odds ratio per score category 0.57, [95% CI 0.34-0.96] p=0.034; 0.62 [95%CI (0.36, 1.07), p=0.09 on further adjustment for birth weight and gestation) compared to children of mothers without PE. In the SDQ, there was a lower prevalence of abnormal 'conduct problem' scores in PE group than non-PE group (OR=0.33, 95% CI 0.13-0.83, p=0.018, in the fully adjusted model); there were no differences for other behavioral domains. This preliminary study in Indian children suggests that fetal exposure to maternal PE may have an adverse impact on visuo-spatial performance but does not adversely affect behavior. Further studies with larger sample sizes are essential to understand effects of maternal PE on cognitive/behavioral outcomes in children.

Comparing CxBladder to Urine Cytology as Adjunct to Cystoscopy in Surveillance of Non-muscle Invasive Bladder Cancer-A Pilot Study

Purpose: Guidelines advocate cystoscopy surveillance (CS) for non-muscle invasive bladder cancer (NMIBC) post-resection. However, cystoscopy is operator dependent and may miss upper tract lesions or carcinoma in-situ (CIS). Urine cytology is a common adjunct but lacks sensitivity and specificity in detecting recurrence. A new mRNA biomarker (CxBladder) was compared with urine cytology as an adjunct to cystoscopy in detecting a positive cystoscopy findings during surveillance cystoscopy in our center.

Materials and Methods: Consented patients older than 18, undergoing CS for NMIBC, provide paired urine samples for cytology and CxBladder test. Patients with positive cystoscopy findings would undergo re-Trans Urethral Resection of Bladder Tumor (TURBT).

Results: Thirty-five patients were enrolled from April to June 2019. Seven contaminated urine samples were excluded. The remaining cohort of 23 (82%) and 5 (18%) females had a mean age of 66.69 (36–89). Eight (29%) patients with positive cystoscopy finding underwent TURBT. All 8 patients also had positive CxBladder result. This shows that CxBladder has a sensitivity and negative predictive value (NPV) of 100%, specificity of 75% and positive predictive value (PPV) of 62% in predicting a positive cystoscopy finding. TURBT Histo-pathological findings showed Low-grade Ta NMIBC in one patient (4%), and 7 (25%) patients had inflammatory changes. Urine cytology was only positive in one patient with a positive cystoscopy finding. This led to a sensitivity of merely 13% and NPV of 74%, while specificity and PPV was 100% in predicting a positive cystoscopy finding.

Conclusion: CxBladder had high NPV and sensitivity which accurately predicted suspicious cystoscopy findings leading to further investigation. It has great potential for use as adjunct to cystoscopy for surveillance of NMIBC.

Comparing BMI with skinfolds to estimate age at adiposity rebound and its associations with cardio-metabolic risk markers in adolescence

Background

Body mass index (BMI) reaches a nadir in mid-childhood, known as the adiposity rebound (AR). Earlier AR is associated with a higher risk of cardio-vascular diseases in later life. Skinfolds, which are a more direct measure of adiposity, may give better insight into the relationship between childhood adiposity and later obesity and cardio-metabolic risk.

Objective

We aimed to assess whether AR corresponds to a rebound in skinfolds, and compare associations of BMI-derived AR and skinfold-derived AR with cardio-metabolic risk markers in adolescence.

Methods

We used penalised splines with random coefficients to estimate BMI and skinfold trajectories of 604 children from the Mysore Parthenon Birth Cohort. Age at AR was identified using differentiation of the BMI and skinfold growth curves between 2 and 10 years of age. At 13.5 years, we measured blood pressure, and glucose, insulin and lipid concentrations.

Results

BMI and skinfolds had different growth patterns. Boys reached BMI-derived AR earlier than skinfold-derived AR (estimated difference: 0.41 years; 95% CI:[0.23, 0.56]), whereas the opposite was observed in girls (estimated difference: −0.71 years; 95% CI:[−0.90, −0.54]). At 13.5 years, children with earlier BMI-derived AR had higher BMI (−0.58 SD per SD increase of AR; 95%CI:[−0.65, −0.52]), fat mass (−0.44; 95%CI:[−0.50, −0.37]), insulin resistance (HOMA-IR: −0.20; 95%CI:[−0.28, −0.12]) and systolic blood pressure (−0.20; 95%CI:[−0.28, −0.11]), and lower HDL-cholesterol (0.12; 95%CI:[0.04, 0.21]). The associations were independent of BMI at time of rebound, but were fully explained by fat mass at 13.5 years. Similar associations were found for skinfold-derived AR.

Conclusion

BMI-derived adiposity rebound predicts later cardio-metabolic risk markers similarly to that derived from skinfolds, a direct measure of adiposity.

Efficacy of a virtual assistance-based lifestyle intervention in reducing risk factors for Type 2 diabetes in young employees in the information technology industry in India: LIMIT, a randomized controlled trial

AIMS

To investigate a virtual assistance-based lifestyle intervention to reduce risk factors for Type 2 diabetes in young employees in the information technology industry in India.

METHODS

LIMIT (Lifestyle Modification in Information Technology) was a parallel-group, partially blinded, randomized controlled trial. Employees in the information technology industry with ≥3 risk factors (family history of cardiometabolic disease, overweight/obesity, high blood pressure, impaired fasting glucose, hypertriglyceridaemia, high LDL cholesterol and low HDL cholesterol) from two industries were randomized to a control or an intervention (1:1) group. After initial lifestyle advice, the intervention group additionally received reinforcement through mobile phone messages (three per week) and e-mails (two per week) for 1 year. The primary outcome was change in prevalence of overweight/obesity, analysed by intention to treat.

RESULTS

Of 437 employees screened (mean age 36.2 ± 9.3 years; 74.8% men), 265 (61.0%) were eligible and randomized into control (n=132) or intervention (n=133) group. After 1 year, the prevalence of overweight/obesity reduced by 6.0% in the intervention group and increased by 6.8% in the control group (risk difference 11.2%; 95% CI 1.2-21.1; P=0.042). There were also significant improvements in lifestyle measurements, waist circumference, and total and LDL cholesterol in the intervention group. The number-needed-to-treat to prevent one case of overweight/obesity in 1 year was 9 (95% CI 5-82), with an incremental cost of INR10665 (£112.30) per case treated/prevented. A total of 98% of participants found the intervention acceptable.

CONCLUSIONS

A virtual assistance-based lifestyle intervention was effective, cost-effective and acceptable in reducing risk factors for diabetes in young employees in the information technology industry, and is potentially scalable.

Determination of the Liquid Water Diffusivity from Transient Moisture Transfer Experiments

The Boltzmann transformation method is used to determine the liquid water diffusivity from moisture content profiles as measured in a capillary water absorption experiment. An inter-laboratory comparison for analyzing the reliability of the determination method showed that the inaccuracy in the liquid water diffusivity is caused by scatter in the transformed data and by uncertainty in the boundary conditions at the intake surface and ahead of the steep moisture front. A methodology is proposed based on (1) the evaluation of the validity of the diffusion approach, (2) a simplified handling of the boundary conditions, (3) smoothing of the scattered data and (4) the evaluation of the quality of the determined liquid water diffusivity. For HAM (Heat-Air-Moisture transport) calculations values of the liquid water diffusivity for moisture contents higher than the capillary moisture content are disregarded. The liquid water diffusivity can be described by an exponential function limited at a lower moisture content bound.

To describe the moisture diffusivity including liquid water and water vapour transports, a new parametric description of the moisture diffusivity is presented, which shows sufficient flexibility both in the hygroscopic and overhygroscopic ranges. When permeability is calculated from diffusivity, the permeability should monotonically increase with decreasing capillary pressure. In the hygroscopic region it should coincide with the measured water vapour permeabilities.

Restructuring Care Teams Within a Neonatal Intensive Care Unit

BACKGROUND: Organizing care teams in a large neonatal intensive care unit (NICU) is a challenge. In our pod-based model, babies were assigned a care team based on acuity and bed location. They were frequently moved between teams to accommodate nursing assignments, causing an imbalance in patient census and acuity across teams. As part of a larger process improvement project, we implemented and studied an alternate model for assigning patients to a care team.

OBJECTIVES: The objective of this project was to improve consistency of patient care and to balance the workload across the three care teams in the NICU.

DESIGN/METHODS: The setting is a 69 bed tertiary teaching NICU with approximately 1300 admissions a year. Three clinical teams share day to day assignment of a combination of these level III and level II pods. A multidisciplinary subgroup conducted a two hour Kaizen (brain storming) event with a larger group of stake-holders during which the decision was made to assign babies to a care team based on current workload of each team. The care teams follow each patient from admission to discharge, regardless of the baby’s location within the unit instead of moving babies between teams. Education communication, feedback strategies regarding the process change were formulated and executed by the sub-group. The new method was piloted for a period of three months. Objective data was collected regarding patient movement, patient acuity, census balance, and rounds time. Qualitative data was collected through staff and family surveys. ignments, causing an imbalance in patient census and acuity across teams. As part of a larger process improvement project, we implemented and studied an alternate model for assigning patients to a care team.

RESULTS: Forty percent of babies admitted to the NICU crossed care teams during their stay prior to the process change while 0.3% changed teams after the change. The number of moves per patient decreased from 1.4 to 1.27. The variability in both census and acuity was diminished following implementation of the changes. The daily average number of man-hours to complete daily rounds decreased from 47.5 before the change to 40.5 after the change. There was a 35% response rate to the staff survey with an overall positive response to the changes with regards to improving the patient and family experience. The family satisfaction survey showed a trend toward increased satisfaction following the change.

CONCLUSION: Process improvement methods can be used to successfully change how care teams are structured in a tertiary NICU.

Body size and body composition: a comparison of children in India and the UK through infancy and early childhood

BACKGROUND

Indian babies are characterised by the 'thin-fat phenotype' which comprises a 'muscle-thin but adipose' body composition compared with European babies. This body phenotype is of concern because it is associated with an increased risk of diabetes and cardiovascular disease. We examined whether the 'thin-fat phenotype' persists through early childhood, comparing Indian children with white Caucasians in the UK at birth, infancy and childhood, using comparable measurement protocols.

METHODS

We used data from two cohorts, the Pune Maternal Nutrition Study (N=631) and the Southampton Women's Survey (N=2643). Measurements of weight, head circumference, mid-upper arm circumference, height, triceps and subscapular skinfold thickness were compared at birth, 1, 2, 3 and 6 years of age. SD scores were generated for the Pune children, using the Southampton children as a reference. Generalised estimating equations were used to examine the changes in SD scores across the children's ages.

RESULTS

The Indian children were smaller at birth in all body measurements than the Southampton children and became relatively even smaller from birth to 2 years, before 'catching up' to some extent at 3 years, and more so by 6 years. The deficit for both skinfolds was markedly less than for other measurements at all ages; triceps skinfold showed the least difference between the two cohorts at birth, and subscapular skinfold at all ages after birth.

CONCLUSIONS

The 'thin-fat phenotype' previously found in Indian newborns, remains through infancy and early childhood. Despite being shorter and lighter than UK children, Indian children are relatively adipose.

Relationships of maternal and paternal birthweights to features of the metabolic syndrome in adult offspring: an inter-generational study in South India

AIMS/HYPOTHESIS

The association between lower birthweight and metabolic syndrome may result from fetal undernutrition (fetal programming hypothesis) and/or genes causing both low birthweight and insulin resistance (fetal insulin hypothesis). We studied associations between the birthweight of parents and metabolic syndrome in the offspring.

METHODS

We identified men and women (aged 35-68 years), who had been born in Holdsworth Memorial Hospital, Mysore, India. We also identified the offspring (20-46 years) of these men and women. In total, 283 offspring of 193 mothers and 223 offspring of 144 fathers were studied. Investigations included anthropometry, oral glucose tolerance, plasma insulin and lipid concentrations and blood pressure. The metabolic syndrome was defined using WHO criteria.

RESULTS

Among the offspring, lower birthweight was associated with an increased risk of glucose intolerance (impaired glucose tolerance, impaired fasting glucose or type 2 diabetes) and higher cholesterol and triacylglycerol concentrations (p < 0.05 for all adjusted for sex and age). Most outcomes in the offspring, including most individual components of the metabolic syndrome, were unrelated to parental birthweight. However, both maternal and paternal birthweight were inversely related to offspring metabolic syndrome (odds ratio [OR] 0.36 [95% CI: 0.13-1.01] per kg, p = 0.053 for mother-offspring pairs; OR 0.26 [0.07-0.93], p = 0.04 for father-offspring pairs, adjusted for offspring age, sex, BMI and socioeconomic status). Maternal birthweight was inversely related to offspring systolic blood pressure (beta = -2.5 mmHg [-5.00 to 0.03] per kg maternal birthweight; p = 0.052).

CONCLUSIONS/INTERPRETATION

Factors in both parents may influence the risk of metabolic syndrome in their offspring. There are several possible explanations, but the findings are consistent with the fetal insulin (genetic) hypothesis.

Human protein reference database--2006 update

Human Protein Reference Database (HPRD) (http://www.hprd.org) was developed to serve as a comprehensive collection of protein features, post-translational modifications (PTMs) and protein-protein interactions. Since the original report, this database has increased to >20 000 proteins entries and has become the largest database for literature-derived protein-protein interactions (>30 000) and PTMs (>8000) for human proteins. We have also introduced several new features in HPRD including: (i) protein isoforms, (ii) enhanced search options, (iii) linking of pathway annotations and (iv) integration of a novel browser, GenProt Viewer (http://www.genprot.org), developed by us that allows integration of genomic and proteomic information. With the continued support and active participation by the biomedical community, we expect HPRD to become a unique source of curated information for the human proteome and spur biomedical discoveries based on integration of genomic, transcriptomic and proteomic data.

Intergenerational effects on size at birth in South India

Several studies have shown that a baby's birthweight correlates with the birthweight and adult size of both its parents, but more strongly with those of its mother, suggesting that both the 'maternal environment' and inherited genes influence size at birth. There are no previous such intergenerational data from India. Holdsworth Memorial Hospital (HMH), Mysore, South India, has preserved birth records containing the birthweight, length and head circumference of all newborns since 1934. We identified 468 mother-offspring and 341 father-offspring pairs born in the hospital. Daughters and sons (born 1990-95) were heavier at birth than their mothers and fathers, respectively, with a mean (SD) increase in birthweight of 121 g (24 g) between the two generations. The birthweight of both parents predicted offspring birthweight equally (mother: regression slope beta = 255 g/kg; father beta = 251 g/kg; P < 0.001 for both). Paternal birth length had a stronger effect than maternal birth length on offspring birth length. The mother's adult body mass index (BMI) had a greater effect than paternal BMI on offspring birthweight (mother: 18 g/kg/m(2); P < 0.001; father: 15 g/kg/m(2); P = 0.04). In a regression model including data for both parents (available for 57 children) this difference was greater (mother: 46 g/kg/m(2); P < 0.001; father: -10 g/kg/m(2); ns). In contrast, paternal height had stronger effects than maternal height on offspring birth length (mother: 0.8 mm/cm; ns; father: 1.5 mm/cm; P < 0.001). In conclusion, size at birth is influenced by a combination of environmental and genetic factors. Both maternal and paternal birthweight correlate with offspring size at birth. Maternal nutritional status (BMI) influences birthweight. Paternal factors appear to contribute to neonatal skeletal size.

Cortisol and the metabolic syndrome in South Asians

OBJECTIVE

The cardiovascular risk factors which comprise the metabolic syndrome are associated with increased hypothalamic-pituitary-adrenal axis (HPAA) activity in some Caucasian populations. South Asians have high rates of cardiovascular disease and its risk factors. We have investigated the relationships between HPAA activity, adiposity and the metabolic syndrome in a South Asian population.

DESIGN

Cross-sectional cohort study.

PARTICIPANTS

A total of 509 men and women born at the Holdsworth Memorial Hospital, Mysore, South India between 1934 and 1954 and still living in the area.

MEASUREMENTS

Fasting 09.00 h cortisol and corticosteroid-binding globulin. The cohort had previously been investigated for features of the metabolic syndrome.

RESULTS

At 09.00 h, cortisol concentration was strongly associated with systolic and diastolic blood pressure (r = 0.25 and r = 0.24, respectively; P < 0.001), fasting glucose concentration (r = 0.26; P < 0.001), insulin resistance (r = 0.20; P < 0.001) and fasting triglyceride concentration (r = 0.17; P < 0.001). In general, higher cortisol concentrations added to the effect of adiposity in increasing cardiovascular risk factors, but there was evidence of an interaction between cortisol and adiposity in determining fasting glucose concentration (P = 0.045) and insulin resistance (P = 0.006).

CONCLUSIONS

Associations between 09.00 h cortisol concentration and cardiovascular risk factors in this South Asian cohort were stronger than those previously shown in Caucasian populations, despite similar mean cortisol concentrations, and were amplified by adiposity. This suggests that increased glucocorticoid action may contribute to ethnic differences in the prevalence of the metabolic syndrome, particularly among men and women with a higher body mass index.

Left ventricular mass and arterial compliance: relation to coronary heart disease and its risk factors in South Indian adults

BACKGROUND

Rates of coronary heart disease (CHD) in India are rising, and are now similar to those in Western countries. The prevalence of conventional CHD risk factors such as hypercholesterolaemia, hypertension, smoking and obesity, tend to be lower in Indian than Western populations, and fail to explain these high rates of disease. Increased left ventricular (LV) mass and decreased arterial compliance predict a higher risk of CHD in Western populations, but there are no published data from India. We have measured LV mass and arterial compliance, and examined their relation to CHD and other known risk factors, in men and women living in Mysore, South India.

METHODS

We examined 435 men and women born in Mysore during 1934-1953. LV mass was measured by echocardiography and arterial compliance (derived from pulse wave velocity, PWV) was measured by a non-invasive optical method in three arterial segments.

RESULTS

The mean LV mass was 149 g (S.D. 37) in men and 125 g (S.D. 32) in women. The mean PWV was 4.14 m/s in the aorto-radial, 3.28 m/s in the aorto-femoral and 13.59 m/s in the femoro-popliteal-posterior tibial segments. LV mass and PWV were positively correlated with each other and with systolic and diastolic blood pressures, non-insulin dependant diabetes mellitus, fasting plasma glucose, insulin, proinsulin concentrations and serum triglyceride concentrations (p<0.05 for all), independently of age, sex and body size. In addition, LV mass correlated negatively with fasting serum HDL-cholesterol (p=0.02). Higher LV mass was associated with an increased risk of CHD (p=0.05).

CONCLUSIONS

The mean LV mass in this Indian population is low compared with Western populations, though as in the West, increased LV mass is associated with an increased risk of CHD. Greater LV mass and reduced arterial compliance are associated with higher levels of many known CHD risk factors especially with those which form the Insulin Resistance Syndrome.

Blood pressure, arterial compliance, and left ventricular mass: no relation to small size at birth in south Indian adults

OBJECTIVE

To determine whether reduced fetal growth leads to raised blood pressure, reduced arterial compliance, and increased left ventricular mass in an Indian population.

DESIGN

A retrospective cohort study of men and women (age range 40-61 years) whose weight, length, and head circumference at birth were recorded.

SETTING

The Holdsworth Memorial Hospital, Mysore, South India.

SUBJECTS

435 men and women born in the hospital between 1934 and 1953.

MAIN OUTCOME MEASURES

Systolic and diastolic blood pressures; compliance in four arterial segments derived from pulse wave velocity, measured by a non-invasive optical method; and left ventricular mass measured using M mode echocardiography.

RESULTS

Small size at birth was not associated with increased adult blood pressure or left ventricular mass, or with reduced arterial compliance. Systolic blood pressure and left ventricular mass were higher in subjects who were greater in length at birth, rising by 1.64 mm Hg (95% confidence interval (CI) -0.08 to +3.37 mm Hg) and 1.63 g/m(2) (95% CI 0.13 to 3.13 g/m(2)), respectively, per one inch (2.5 cm) increase in birth length, independently of adult size. Arterial compliance was reduced in people whose mothers were lighter and had smaller pelvic (external conjugate) diameters.

CONCLUSIONS

The higher prevalence of coronary heart disease in Indian men and women of lower birth weight, shown in an earlier study of the same cohort, cannot be explained by changes in blood pressure, arterial compliance, and left ventricular mass. The association of raised blood pressure and left ventricular mass with longer birth length suggests that the way in which the intrauterine environment influences coronary heart disease differs between Indian and Western populations.

Size at birth, maternal weight, and type 2 diabetes in South India

Recent research in Europe and the USA has shown that adults who had a low birthweight or who were thin at birth with a low ponderal index (birthweight/length3) tend to be insulin resistant and have an increased risk of developing Type 2 diabetes mellitus. Low birthweight and Type 2 diabetes are common in India. We have studied glucose and insulin metabolism in 506 men and women (aged 39-60 years) born in a hospital in Mysore, South India, which kept detailed obstetric records from 1934. The prevalence of Type 2 diabetes was 15%. In contrast to Western populations, higher rates were found in men and women who were short at birth (p = 0.07) and had a high ponderal index (p = 0.05). Their mothers tended to be heavier than average during pregnancy (p = 0.004). Higher ponderal index at birth was also associated with a lower 30 minute insulin increment (p = 0.009), a marker of reduced beta cell function. We speculate that the rise in Type 2 diabetes in Indian urban populations may have been triggered by mild obesity in mothers, leading to glucose intolerance during pregnancy, macrosomic changes in the fetus, and insulin deficiency in adult life.

Relation of fetal growth to adult lung function in south India

BACKGROUND

Follow up studies in Britain have shown that low rates of fetal growth are followed by reduced lung function in adult life, independent of smoking and social class. It is suggested that fetal adaptations to undernutrition in utero result in permanent changes in lung structure, which in turn lead to chronic airflow obstruction. India has high rates of intrauterine growth retardation, but no study has examined the association between fetal growth and adult lung function in Indian people. We have related size at birth to lung function in an urban Indian population aged 38-59 years.

METHODS

Two hundred and eighty six men and women born in one hospital in Mysore City, South India, during 1934-1953 were traced by a house-to-house survey of the city. Their mean forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were measured using a turbine spirometer. These measurements were linked to their size at birth, recorded at the time.

RESULTS

In both men and women mean FEV1 fell with decreasing birthweight. Adjusted for age and height, it fell by 0.09 litres with each pound (454 g) decrease in birthweight in men (95% confidence interval (CI) 0.01 to 0.16) and by 0.06 (95% CI -0.01 to 0.13) in women. Likewise, mean FVC fell by 0.11 litres (95% CI 0.02 to 0.19) with each pound decrease in birthweight in men, and by 0.08 litres (95% CI 0.002 to 0.16) in women. FEV1 and FVC were lower in men who smoked, but the associations with size at birth were independent of smoking. Small head circumference at birth was associated with a low FEV1/FVC ratio in men which may reflect restriction in airway growth in early gestation.

CONCLUSION

This is further evidence that adult lung function is "programmed" in fetal life. Smoking may be particularly detrimental to the lung function of populations already disadvantaged by poor rates of fetal growth.

Fetal growth and coronary heart disease in south India

BACKGROUND

Coronary heart disease is predicted to become the commonest cause of death in india within 15 years People from India living overseas already have high rates of the disease that are not explained by known coronary risk factors. Small size at birth is a newly described risk factor for coronary heart disease, but associations between size at birth and the disease have not been examined in India.

METHODS

We studied 517 men and women who were born between 1934 and 1954 in a mission hospital in Mysore, South India, and who still lived near to the hospital. We related the prevalence of coronary heart disease, defined by standard criteria, to their birth size.

FINDINGS

25 (9%) men and 27 (11%) women had coronary heart disease. Low birthweight, short birth length, and small head circumference at birth were associated with a raised prevalence of the disease. Prevalence fell from 11% in people whose birthweights were 5.5 lb (2.5 kg) or less to 3% in those whose birthweights were more than 7 lb (3.1 kg), p for trend = 0.09. The trends were stronger and statistically significant among people aged 45 years and over (p = 0.03 for birthweight, 0.04 for length, and 0.02 for head circumference). High rates of disease were also found in those whose mothers had a low body weight during pregnancy. The highest prevalence of the disease (20%) was in people who weighted 5.5 lb (2.5 kg) or less at birth and whose mothers weighted less than 100 lb (45 kg) in pregnancy. These associations were largely independent of known coronary risk factors.

INTERPRETATION

In India, as in the UK, coronary heart disease is associated with small size at birth, suggesting that its pathogenesis is influenced by events in utero. The association with low maternal bodyweight is further evidence that the disease originates through fetal undernutrition. Prevention of the rising epidemic of the disease in India may require improvements in the nutrition and health of young women.

Gluconeogenesis and glucuronidation in liver in vivo and the heterogeneity of hepatocyte function

In order to examine metabolic zonation in human liver, [2-14C]glycerol, which labels carbons 2 and 5 of glucose-6-P, and [1-14C]lactate, which labels carbons 3 and 4 of glucose-6-P, in the process of gluconeogenesis, were infused intravenously into healthy subjects who ingested acetaminophen and had fasted 36 h. Distributions of 14C were determined in glucose in blood and in the glucuronic acid moiety of acetaminophen glucuronide excreted in urine. Ratios of 14C in carbons 2 and 5 to 14C in carbons 3 and 4 were significantly higher in blood glucose than in glucuronide. Since glucose and glucuronic acid are formed from glucose-6-P in liver without randomization of carbon, the differences in the ratios indicate that the pool of glucose-6-P in liver is not homogeneous. The glucuronide sampled glucose-6-P with more label from lactate than glycerol compared to the glucose-6-P sampled by the glucose. The apparent explanation is the greater decrease in glycerol compared with lactate concentration as blood streams from the periportal to the perivenous zones of the liver lobule. Glucuronidation is then expressed in humans relatively more in the perivenous than periportal zones and gluconeogenesis from glycerol more in the periportal than perivenous zones.

Estimates of Krebs cycle activity and contributions of gluconeogenesis to hepatic glucose production in fasting healthy subjects and IDDM patients

Normal subjects, fasted 60 h, and patients with insulin-dependent diabetes mellitus (IDDM), withdrawn from insulin and fasted overnight, were given phenylacetate orally and intravenously infused with [3-14C]lactate and 13C-bicarbonate. Rates of hepatic gluconeogenesis relative to Krebs cycle rates were estimated from the 14C distribution in glutamate from urinary phenylacetylglutamine. Assuming the 13C enrichment of breath CO2 was that of the CO2 fixed by pyruvate, the enrichment to be expected in blood glucose, if all hepatic glucose production had been by gluconeogenesis, was then estimated. That estimate was compared with the actual enrichment in blood glucose, yielding the fraction of glucose production due to gluconeogenesis. Relative rates were similar in the 60-h fasted healthy subjects and the diabetic patients. Conversion of oxaloacetate to phosphoenolpyruvate was two to eight times Krebs cycle flux and decarboxylation of pyruvate to acetyl-CoA, oxidized in the cycle, was less than one-30th the fixation by pyruvate of CO2. Thus, in estimating the contribution of a gluconeogenic substrate to glucose production by measuring the incorporation of label from the labelled substrate into glucose, dilution of label at the level of oxaloacetate is relatively small. Pyruvate cycling was as much as one-half the rate of conversion of pyruvate to oxaloacetate. Glucose and glutamate carbons were derived from oxaloacetate formed by similar pathways if not from a common pool. In the 60-h fasted subjects, over 80% of glucose production was via gluconeogenesis. In the diabetic subjects the percentages averaged about 45%.

Quantitation of the pathways followed in the conversion of fructose to glucose in liver

Recently, only about 50% of the conversion of fructose to glucose was reported to be via fructose-1-P aldolase catalysis in children. This was also suggested to be the case in adults. That possibility has been tested using a method that quantifies the pathways of fructose conversion to glucose via the fate of 14C from specifically labeled fructose. Trace [6-14C] fructose or its immediate precursor [6-14C]sorbitol with unlabeled fructose (0.3 mg/kg body weight/min) was given intravenously or intragastrically with trace [1-14C]lactate to six normal adults fasted overnight. The distributions of 14C in glucose from blood samples were determined. The ratios of 14C in C1 to C6 of the glucose were equal to or only slightly less than the ratios of 14C in C3 to C4. Since incorporation into C3 and C4 of glucose must have arisen via the conversion of [1-14C]lactate to [1-14C]triose phosphates, fructose conversion to glucose must also have arisen predominantly via the triose phosphates. From the ratios, 85.1% to 100%, a mean of 94.9% of the fructose converted to glucose is calculated to have been converted to glucose with cleavage of the carbon skeleton of the fructose. These findings contrast with the report that in children under similar conditions only about 50% of the conversion of fructose to glucose is with cleavage. The findings agree with previous results in which fructose was administered to normal adults as a bolus at a dose of 60 mg/kg body weight. The possible reasons that the findings in children are different from those in adults are considered.

14C-labeled propionate metabolism in vivo and estimates of hepatic gluconeogenesis relative to Krebs cycle flux

Purposes of this study were 1) to estimate in humans, using 14C-labeled propionate, the rate of hepatic gluconeogenesis relative to the rate of Krebs cycle flux; 2) to compare those rates with estimates previously made using [3-14C]lactate and [2-14C]acetate; 3) to determine if the amount of ATP required for that rate of gluconeogenesis could be generated in liver, calculated from that rate of Krebs cycle flux and splanchnic balance measurements, previously made, and 4) to test whether hepatic succinyl-CoA is channeled during its metabolism through the Krebs cycle. [2-14C]propionate, [3-14C]-propionate, and [2,3-14C]succinate were given along with phenyl acetate to normal subjects, fasted 60 h. Distributions of 14C were determined in the carbons of blood glucose and of glutamate from excreted phenylacetylglutamine. Corrections to the distributions for 14CO2 fixation were made from the specific activities of urinary urea and the specific activities in glucose, glutamate, and urea previously found on administering [14C]-bicarbonate. Uncertainties in the corrections and in the contributions of pyruvate and Cori cyclings limit the quantitations. The rate of gluconeogenesis appears to be two or more times the rate of Krebs cycle flux and pyruvate's decarboxylation to acetyl-CoA, metabolized in the cycle, less than one-twenty-fifth the rate of its decarboxylation. Such estimates were previously made using [3-14C]lactate. The findings support the use of phenyl acetate to sample hepatic alpha-ketoglutarate. Ratios of specific activities of glucose to glutamate and glucose to urinary urea and expired CO2 indicate succinate's extensive metabolism when presented in trace amounts to liver. Utilizations of the labeled compounds by liver relative to other tissues were in the order succinate = lactate > propionate > acetate. ATP required for gluconeogenesis and urea formation was approximately 40% of the amount of ATP generated in liver. There was no channeling of succinyl-CoA in the Krebs cycle in the hepatic mitochondria.

Use of 14CO2 in estimating rates of hepatic gluconeogenesis

Estimating the rate of hepatic gluconeogenesis in vivo from the incorporation of 14C from 14CO2 into glucose requires determination of the rates in liver of equilibration of oxaloacetate with fumarate, conversion of oxaloacetate to phosphoenolpyruvate (PEP), and conversion of PEP to pyruvate, all relative to the rate of tricarboxylic acid cycle flux. With the use of a model of mitochondrial metabolism and gluconeogenesis, expressions are derived relating specific activity of carboxyl of PEP from 14CO2 to those rates and specific activity of mitochondrial CO2. If those rates and specific activity of mitochondrial CO2 are known, specific activity of PEP, calculated using the expressions, should, on a mole basis, be one-half the specific activity of the glucose formed. At steady state, in the 60-h fasted individual, where glucose formation is solely by gluconeogenesis, twice estimated specific activity of PEP should then approximate that of blood glucose. Estimates of relative rates in 60-h fasted humans, previously made from distribution of 14C in glutamate from phenylacetylglutamine excreted when [3-14C]lactate and phenylacetate were given, were applied to the expressions. Specific activity of mitochondrial CO2 was equated to that of CO2 expired by 60-h fasted subjects given NaH14CO3 and alpha-[1-14C]ketoisocaproate. Predicted specific activities approximated actual specific activities of blood glucose when NaH14CO3 was administered. alpha-[1-14C]ketoisocaproate administrations gave underestimates. This is attributable to differences between specific activities of hepatic mitochondrial CO2 and expired CO2, which is evidenced by higher incorporations of 14C in glucose than in expired CO2 from alpha-[1-14C]ketoisocaproate than from NaH14CO3.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism of [2-14C]acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis

To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, [2-14C]acetate, [2-14C]ethanol, and [1-14C]ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of 14C in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With [2-14C]acetate and [2-14C]ethanol, carbon 1 of glucose had about twice as much 14C as carbon 3. Carbon 2 of glutamate had about twice as much 14C as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of [2-14C]acetate being primarily in liver. Therefore, [2-14C]acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from [2-14C]acetate in the formation of the 14C-labeled glucose and glutamate in liver and (b) the formation of 14C-labeled glutamate in a second site, proposed to be muscle. [1,3-14C]Acetone formation from the [2-14C]acetate does not contribute to the distributions, as evidenced by the absence of 14C in carbons 2-4 of glutamate after [1-14C]ethanol administration.

Noninvasive tracing of Krebs cycle metabolism in liver

To quantify intrahepatic Krebs cycle metabolism, phenyl acetate, excreted in urine as a glutamine conjugate, was given to healthy subjects infused with [3-14C]lactate. They were studied after 60 h of fasting and when given glucose after an overnight fast. Distributions of 14C in glutamate from urinary phenylacetylglutamine and blood glucose were determined. Corrections to the distributions because of the fixation of 14CO2 formed from the [3-14C]lactate were determined by administering [14C]bicarbonate. Comparisons of distributions in glucose and glutamate support the assumption that the glutamate distributions reflect those in hepatic alpha-ketoglutarate. From the distributions in glutamate, the extent of exchange of labeled with unlabeled carbons and relative flow rates in the cycle in liver were estimated. Dilution of 14C by 12C in the cycle was found in the fasted but not the fed state. In the fasted state, pyruvate carboxylation was estimated to be at least twice the rate of Krebs cycle flux and the rate of pyruvate's decarboxylation less than 1/25 the rate of its carboxylation. In the fed state, the rate of decarboxylation was estimated to be between one-sixth and one-half the rate of carboxylation. The rate of conversion of oxalacetate to fumarate in both states appeared to be greater than 6 times the rate of Krebs cycle flux.

Quantitative comparison of pathways of hepatic glycogen repletion in fed and fasted humans

The effect of fasting vs. refeeding on hepatic glycogen repletion by the direct pathway, i.e., glucose----glucose 6-phosphate (G-6-P)----glycogen, was determined. Acetaminophen was administered during an infusion of glucose labeled with [1-13C]- and [6-14C]glucose into four healthy volunteers after an overnight fast and into the same subjects 4 h after breakfast. 13C enrichments in C-1 and C-6 of glucose formed from urinary acetaminophen glucuronide compared with enrichments in C-1 and C-6 of plasma glucose provided an estimate of glycogen formation by the direct pathway. The specific activity of glucose from the glucuronide compared with the specific activity of the plasma glucose, along with the percentages of 14C in C-1 and C-6 of the glucose from the glucuronide, also provided an estimate of the amount of glycogen formed by the direct pathway. The estimates were similar. Those from [6-14C]glucose would have been higher than from [1-13C]glucose if the pentose cycle contribution to overall glucose utilization had been significant. After an overnight fast, during the last hour of infusion, 49 +/- 3% of the glycogen formed was formed via the direct pathway. After breakfast, at similar plasma glucose and insulin concentrations, the percentage increased to 69 +/- 7% (P less than 0.02). Thus the contributions of the pathways to hepatic glycogen formation depend on the dietary state of the individual. For a dietary regimen in which individuals consume multiple meals per day containing at least a moderate amount of carbohydrates most glycogen synthesis occurs by the direct pathway.

Fructose-6-phosphate cycling and the pentose cycle in hyperthyroidism

Hepatic fructose-6-phosphate (fructose-6-P) cycling and pentose cycle activity were quantified in hyperthyroid patients. A measure of the fructose-6-P cycle was the incorporation of 14C, on administering [3-3H,6-14C]galactose, into carbon 1 of blood glucose and the 3H/14C ratio in blood glucose. The measure of the pentose cycle was the randomization of 14C to carbon 1 of blood glucose on administering [2-14C]galactose. [2-3H]Galactose was also administered, so the 3H/14C ratio in blood glucose measured the extent of equilibration of glucose-6-P with fructose-6-P. Patients given [3-3H,6-14C]galactose were restudied when euthyroid. Of the 14C from [3-3H,6-14C]galactose, 7.7-9.5% was in carbon 1 of glucose in both states. 3H/14C ratios were also the same in both states. Fructose-6-P cycling was estimated to be 13 +/- 1% the rate of glucose turnover in the euthyroid and 15 +/- 1% that in the hyperthyroid state. The pentose cycle contributed about 2% to glucose utilization, similar to previous estimates in healthy humans. As in healthy individuals, about 25% of 3H was retained in the conversion of [2-3H]glucose-6-P to glucose. Thus, the fractions of glucose turnover participating in hepatic fructose-6-P and pentose cycling are similar in hyperthyroid and healthy subjects. As a result, augmented fructose-6-P cycling does not substantially contribute to increased hepatic oxygen consumption in hyperthyroidism.

Pathways of hepatic glycogen formation in humans following ingestion of a glucose load in the fed state

The relative contributions of the direct and the indirect pathways to hepatic glycogen formation following a glucose load given to humans four hours after a substantial breakfast have been examined. Glucose loads labeled with [6-(14)C]glucose were given to six healthy volunteers along with diflunisal (1 g) or acetaminophen (1.5 g), drugs excreted in urine as glucuronides. Distribution of 14C in the glucose unit of the glucuronide was taken as a measure of the extent to which glucose was deposited directly in liver glycogen (ie, glucose----glucose-6-phosphate----glycogen) rather than indirectly (ie, glucose----C3-compound----glucose-6-phosphate----glycogen). The maximum contribution to glycogen formation by the direct pathway was estimated to be 77% +/- 4%, which is somewhat higher than previous estimates in humans fasted overnight (65% +/- 1%, P less than 0.05). Thus, the indirect pathway of liver glycogen formation following a glucose load is operative in both the overnight fasted and the fed state, although its contribution may be somewhat less in the fed state.

Testing of the assumptions made in estimating the extent of futile cycling

In estimating glucose and fructose 6-phosphate futile cycling in vivo, complete detritiation of [2-3H]glucose is assumed at the glucose 6-phosphate level, [3-3H]glucose at triose phosphate formation, and [6-3H]glucose in its conversion to glucose via pyruvate. [3-3H]glucose detritiation via the pentose cycle is assumed to be negligible. Normal and non-insulin-dependent diabetic subjects, in the basal state and infused with glucose, were given [2-3H,2-14C]galactose, and 3H-to-14C ratios in blood glucose were determined. [2-3H,2-14C]glucose was given with acetaminophen, and 3H/14C in urinary glucuronide was determined. Detritiation at glucose 6-phosphate was approximately 80%. [3-3H,1-14C]fructose was infused, and 3H/14C was determined in blood glucose and urinary glucuronide. At triose phosphate, 75-90% of the 3H was removed. The pentose cycle contribution was only a few percent. [6-3H,6-14C]glucose was infused, and 3H/14C in blood lactate was determined. [3-3H,3-14C]lactate was infused, and ratios in blood glucose were determined. Maximally, 10% of 3H from [6-3H]glucose was retained. If glucose and galactose are metabolized in the same hepatic site(s), glucose conversion to three-carbon intermediates in the indirect pathway of glycogen formation occurs in extrahepatic tissue(s). Reported estimates of futile cycling, although qualitatively correct, quantitatively require correction.

Pentose pathway in human liver

[1-14C]Ribose and [2-14C]glucose were given to normal subjects along with glucose loads (1 g per kg of body weight) after administration of diflunisal and acetaminophen, drugs that are excreted in urine as glucuronides. Distributions of 14C were determined in the carbons of the excreted glucuronides and in the glucose from blood samples drawn from hepatic veins before and after glucagon administration. Eighty percent or more of the 14C from [1-14C]ribose incorporated into the glucuronic acid moiety of the glucuronides was in carbons 1 and 3, with less than 8% in carbon 2. In glucuronic acid from glucuronide excreted when [2-14C]glucose was given, 3.5-8.1% of the 14C was in carbon 1, 2.5-4.3% in carbon 3, and more than 70% in carbon 2. These distributions are in accord with the glucuronides sampling the glucose unit of the glucose 6-phosphate pool that is a component of the pentose pathway and is intermediate in glycogen formation. It is concluded that the glucuronic acid conjugates of the drugs can serve as a noninvasive means of sampling hepatic glucose 6-phosphate. In human liver, as in animal liver, the classical pentose pathway functions, not the L-type pathway, and only a small percentage of the glucose is metabolized via the pathway.

Quantitation of the pathways of hepatic glycogen formation on ingesting a glucose load

Diflunisal, 5-(2',4'-difluorophenyl)salicylic acid, excreted in urine as its glucuronide, was given to normal humans (n = 6) along with a glucose load specifically labeled with 14C. Glucuronide excreted by each subject was reduced to its glucoside and glucose from it degraded to yield the distribution of 14 C in its six carbons. Randomization of the 14C from the specifically labeled glucose was taken as a measure of the extent to which glucose was deposited indirectly (i.e., glucose----lactate----glucose----6-P----glycogen), rather than directly (i.e., glucose----glucose-6-P----glycogen). The maximum contribution to glycogen formation by the direct pathway was estimated to be 65 +/- 1%, on the assumption that glucuronide and glycogen are derived from the same hepatic pool of glucose-6-P in liver. Evidence that supports that assumption was obtained by comparing the randomization of 14C in the urinary glucuronide with that in glucose in blood from the hepatic vein of four of the subjects before and after they were given glucagon. Other evidence supporting the assumption was obtained by comparing in two subjects 3H/14C ratios in glucose from hepatic vein blood before and after glucagon administration with that in urinary glucuronide, having labeled the uridine diphosphate (UDP)-glucose in their livers with 14C by giving them 1-[14C]galactose and their circulating glucose with 3H by giving a 5-[3H]glucose-labeled load. It is concluded that glucuronide formation in humans can be used to trace glucose metabolism in the liver, and that in humans the indirect pathway of glucose metabolism is active.

Determinants in the pathways followed by the carbons of acetone in their conversion to glucose

[2-14C]Acetone was infused into rats that were fed or fasted. Each was infused with either a trace quantity of acetone or a large quantity that resulted in a blood concentration of acetone of at least 4 mM. The distribution of 14C in the carbons of glucose from each rat was determined. Two of the rats were given acetone in their drinking water and one was diabetic. Whether a rat was chronically exposed to acetone, fed or fasted, normal or diabetic, if given the trace dose, over 80% of the 14C in the glucose it formed was in carbons 1, 2, 5, and 6 of the glucose. If a rat was given the large dose, about 50% was in carbons 3 and 4. Thus, the major determinant of the pathways followed by acetone when it is metabolized is its concentration and not the prior dietary state of the animal or its previous exposure to acetone. Incorporation into carbons 1, 2, 5, and 6 occurs in the conversion of the carbons of [2-14C]lactate into glucose, whereas incorporation into carbons 3 and 4 occurs in the conversion of the carbons of [1-14C]acetate into glucose. Therefore, at high acetone concentration, the pathway that has been proposed for acetone's metabolism via acetate predominates, and via acetate there can be no net synthesis of glucose from acetone. When rats were given cyanamide and then the large dose of acetone, 74% of the 14C in the glucose they formed was in carbons 3 and 4 of the glucoses. Thus, the relative contribution of the pathway to lactate, or its metabolic equivalent, that has been proposed appears to be lessened by the administration of an aldehyde dehydrogenase inhibitor.

Pathways of acetone's metabolism in the rat

Distributions of 14C were different from those of 13C in glucoses formed by livers of rats in diabetic ketosis and perfused with [2-14C]acetone and [2-13C]lactate. There was 32-73% of the 14C and 8-12% of the 13C in carbons 3 and 4 of the glucoses with the remaining 14C and 13C distributed about equally in the other carbons. Incorporations of 14C from [2-14C]acetone (14-39%) also exceeded those from [2-14C]pyruvate (8-10%) into carbons 3 and 4 of glucoses formed by hepatocytes from rats fed acetone or fasted. [2-14C]Acetone and [2-14C]pyruvate were infused into rats that were fed, fasted, given acetone in their drinking water, or in diabetic ketosis. Thirty-seven to 52% of the 14C in the glucoses formed was in their carbons 3 and 4 when the acetone was infused and 8 to 14% when the pyruvate was infused. [1,3-14C]Hydroxybutyrate was formed by the rats in diabetic ketosis given [2-14C]acetone. It is concluded that acetone is metabolized in rats to a large extent by a pathway in which lactate or its metabolic equivalent is not an intermediate and that pathway is via acetyl-CoA. via acetyl-CoA.

The nature of the pentose pathway in liver

[2-14C]Glucose, [3,4-14C]glucose, [5-14C]glucose, [4,5,6-14C]glucose, and [1-14C]ribose were perfused through livers of rats. The rats were fed or fasted and refed. In one experiment the liver perfused was regenerating and in another phenazine methosulfate was in the perfusate. Perfusion was for 30 or 90 min. Glucose from each perfusate and liver glucose-6-P and glycogen were isolated, purified, and degraded. The distributions of 14C in the carbons of the glucoses from the glycogens are similar to the distributions from the glucose 6-phosphates. The distributions of 14C are in accord with metabolism of glucose by the classical pentose pathway and not by the L-type pathway that has been proposed to function in liver.

Quantitative estimation of the pathways followed in the conversion to glycogen of glucose administered to the fasted rat

When [6-3H,6-14C]glucose was given in glucose loads to fasted rats, the average 3H/14C ratios in the glycogens deposited in their livers, relative to that in the glucoses administered, were 0.85 and 0.88. When [3-3H,3-14C]lactate was given in trace quantity along with unlabeled glucose loads, the average 3H/14C ratio in the glycogens deposited was 0.08. This indicates that a major fraction of the carbons of the glucose loads was converted to liver glycogen without first being converted to lactate. When [3-3H,6-14C]glucose was given in glucose loads, the 3H/14C ratios in the glycogens deposited averaged 0.44. This indicates that a significant amount of H bound to carbon 3, but not carbon 6, of glucose is removed within liver in the conversion of the carbons of the glucose to glycogen. This can occur in the pentose cycle and by cycling of glucose-6-P via triose phosphates: glucose----glucose-6-P----triose phosphates----glucose-6-P----glycogen. The contributions of these pathways were estimated by giving glucose loads labeled with [1-14C]glucose, [2-14C]glucose, [5-14C]glucose, and [6-14C]glucose and degrading the glucoses obtained by hydrolyzing the glycogens that deposited. Only a few per cent of the glucose carbons deposited in glycogen were deposited in liver via glucose-6-P conversion to triose phosphates. Between 4 and 9% of the glucose utilized by the liver was utilized in the pentose cycle. While these are relatively small percentages, since three NADP3H molecules are formed from each molecule of [3-3H]glucose-6-P utilized in the cycle, a major portion of the difference between the ratios obtained with [3-3H]glucose and with [6-3H]glucose is attributable to metabolism in the pentose cycle. Because 3H of [3-3H]glucose is extensively removed during the conversion of the glucose to glycogen within liver the extent of incorporation of the 3H into liver glycogen is not the measure of glucose's metabolism in other tissues before its carbons are deposited in liver glycogen. The distributions of 14C from the 14C-labeled glucoses into the carbons of the liver glycogens mean that at a minimum about 30% of the carbons of the glucose deposited in the glycogen were first converted to lactate or its metabolic equivalent.

Ketone body production in diabetic ketosis by other than liver

To determine if ketone bodies, synthesized from fatty acids by tissues other than the liver, enter the circulation, rats in diabetic ketosis were injected with sodium [6,13-14C]palmitate. Hydroxybutyrate was isolated from the urine excreted by each rat and from an aqueous extract of its carcass. The distribution of 14C in the four carbons of hydroxybutyrate in the extract was the same as in the urine. The ratio of 14C in carbon 1 to carbon 3 of the hydroxybutyrate averaged 1.80 and averaged 1.31 in carbon 2 to carbon 4. Hydroxybutyrate when formed by perfused liver has the same carbon 1-to-carbon 3 ratio as carbon 2-to-carbon 4 ratio. The results indicate that hydroxybutyrate synthesized by tissues other than the liver mixes in the circulation with that synthesized by the liver and a portion of the mix is then excreted in the urine. The difference between the carbon 1-to-3 carbon ratio 3 and carbon 2-to-carbon 4 ratio calculates to an estimated minimum of 15% to 17% of the hydroxybutyrate in the circulation of the ketotic diabetic rat having tissues other than the liver as its source. Assuming the liver and kidneys are the sources of the ketone bodies in diabetic ketosis, the ketone bodies produced by the kidneys are not excreted into the urine without first entering the circulation.

The tracing of the pathway of mevalonate's metabolism to other than sterols

Specifically 14C-labeled mevalonic acids were administered to rats in diabetic ketosis, and the distribution of 14C was determined in the hydroxybutyric acid each rat excreted. Also, the distributions of 14C were determined in hydroxybutyric acid formed by slices of livers and kidneys from rats in diabetic ketosis and incubated with the specifically labeled mevalonic acids. The distributions found are in accord with the conversion of mevalonate to hydroxymethylglutaryl-CoA by the shunt pathway proposed by J. Edmond and G. Popják ((1974) J. Biol. Chem. 249, 66-71). That is, carbon 5 of mevalonate was metabolized to form the carboxyl of acetyl-CoA and carbons 2 and 3 of mevalonate were converted in large measure to hydroxybutyric acid without acetyl-CoA as an intermediate, i.e. the bond between carbon 2 and 3 was not cleaved, while the bond between 1 and 2, traced with [1,2-14C]mevalonate, was cleaved. Similar distributions of 14C were found in hydroxybutyric acid excreted by rats in diabetic ketosis administered specifically 14C-labeled isovaleric acids, isovaleric acid having in its metabolism intermediates common to those in the shunt pathway.

A method for quantitating the contributions of the pathways of acetoacetate formation and its application to diabetic ketosis in vivo

A method has been developed for estimating in the intact cell the contribution of deacylation of acetoacetyl-CoA to the formation of acetoacetate relative to acetoacetate's formation via hydroxymethylglutaryl (HMG)-CoA. Estimates depend upon the fraction of the terminal four carbons of an even carbon-containing fatty acid that are converted to acetoacetate without prior conversion to acetyl-CoA, since in the formation of acetoacetate via HMG-CoA the omega-2 and omega-3 carbons of the fatty acid are converted to acetyl-CoA. Incorporation of 14C from [16-14C]palmitic acid into carbon 2 relative to carbon 4 of acetoacetate is used as the measure of the formation of the acetoacetate from the omega and omega-1 carbons of the fatty acid without acetyl-CoA as an intermediate. Incorporation of 14C from [13-14C]palmitic acid into carbon 1 relative to carbon 3 of acetoacetate is the measure of the formation of acetoacetate from the omega-2 and omega-3 carbons without acetyl-CoA as an intermediate. Comparison of these incorporations is made with incorporation into the carbons of acetoacetate of 14C from palmitic acid labeled with 14C in any of its first 12 carbons since such incorporation must proceed via acetyl-CoA as an intermediate. In an application of this approach, the specifically 14C-labeled palmitic acids were injected into rats in diabetic ketosis. Hydroxybutyric acid that each rat excreted was isolated and degraded. From the ratios of incorporation into the carbons of the hydroxybutyrates, as a minimum, 11% of the total quantity of hydroxybutyrate excreted by the rats was formed from acetoacetyl-CoA without HMG-CoA as an intermediate.

Pathways of acetoacetate's formation in liver and kidney

Specifically 14C-labeled palmitic acids were perfused through livers and incubated with slices of kidneys from rats in diabetic ketosis. The distribution of 14C in the hydroxybutyric acid formed was determined. In liver, the ratio of incorporation of 14C from [13-14C]palmitic acid into carbon 1 to carbon 3 of the hydroxybutyric acid was the same as the ratio in carbon 2 to carbon 4 from [6-14C]palmitic acid. In kidney, the carbon 1-to-carbon 3 ratio was more than twice the carbon 2-to-carbon 4 ratio. In both tissues, 14C from [16-14C] palmitic acid was preferentially incorporated into carbon 4 compared to carbon 2 of the hydroxybutyric acid, but more so in liver than kidney. These results mean that in liver, the sole pathway of acetoacetate formation is via hydroxymethylglutaryl-CoA, while in kidney it is not. Rather in kidney, acetoacetyl-CoA is converted to acetoacetate to a large extent by direct deacylation, presumably via a transferase- and/or deacylase-catalyzed reaction. In liver, most of the palmitic acid utilized is converted to acetoacetate while in kidney it is not. We previously estimated that, as a minimum, 11% of the hydroxybutyric acid excreted by the rat in diabetic ketosis is formed without hydroxymethylglutaryl-CoA as an intermediate. The kidney appears to be the source of this hydroxybutyric acid if the pathways operative in these tissues in vitro are those that also operate in vivo.