Studies of the SIM1 gene in relation to human obesity and obesity-related traits.

OBJECTIVE: The single-minded 1 (SIM1) is a basic helix-loop-helix transcription factor, which plays a critical role in the development of the paraventricular nucleus (PVN) of the hypothalamus. SIM1-deficient mice have a hypocellular PVN and are severely obese with increased food intake. DESIGN: We examined whether variants in the SIM1 gene might be associated with severe early-onset obesity in humans. Two hundred and seventy-seven subjects with hyperphagia and severe, early-onset obesity were screened. Association studies with common single-nucleotide polymorphisms (SNPs) in the SIM1 gene were performed in two population-based cohorts. RESULTS: One novel missense mutation, I128T, was found in one obese subject and not in 192 controls. However, the variant did not co-segregate with obesity in the family. Four SNPs, IVS4+83GA, P352T, A371V and T653T, were also identified. The two common SNPs, P352T and A371V, which are in complete linkage disequilibrium, were genotyped in 981 subjects from a population-based cohort, the Ely Study. An allele frequency of 0.13 was observed. Male subjects carrying the P352T/A371V haplotype were found to have a slightly higher body mass index (BMI; P=0.038). Female subjects homozygous for the haplotype gained more weight over a period of 4.5 and 10 years (P=0.003 and P=0.02, respectively). The association studies were repeated in another population-based cohort, the European Prospective Investigation into Cancer and Nutrition (EPIC) - Norfolk Study with 4869 subjects successfully genotyped. Male subjects homozygous for the P352T/A371V haplotype had slightly higher BMI (P=0.04). CONCLUSION: Mutations in SIM1 are not commonly found in humans with severe early-onset obesity. The relationship between the common variants in SIM1 with BMI and body weight gain deserves further exploration in other populations.

Partial leptin deficiency and human adiposity.

The adipocyte-derived hormone leptin is crucial for energy homeostasis in mammals; mice and humans without it suffer from a voracious appetite and extreme obesity. The effect on energy balance of variations in plasma leptin above a minimal threshold is uncertain, however, particularly in humans. Here we examine a group of individuals who are genetically partially deficient in leptin, and show that differences in circulating leptin levels within the range found in normal human populations can directly influence the laying down of fat tissue (adiposity).

Developmental outcomes of newborn encephalopathy in the term infant.

Newborn encephalopathy is a clinically defined condition of abnormal neurological behaviours in the newborn period. Though most cases have their origin in the preconceptional and antepartum period, newborn encephalopathy represents a crucial link between intrapartum events and permanent neurological problems in the child. The birth prevalence of newborn encephalopathy ranges from 1.8 to 7.7 per 1000 term live births according to the definition used and the population to which it is applied. Few studies have investigated the outcomes of newborn encephalopathy other than for cases solely attributed to intrapartum hypoxia. These adverse outcomes range from death to cerebral palsy, intellectual disability, and less severe neurological disabilities such as learning and behavioural problems. Outcomes following newborn encephalopathy may vary from country to country with 9.1% of affected babies dying in the newborn period in Western Australia and 10.1% manifesting cerebral palsy by the age of two. These compare to a case fatality of 30.5% in Kathmandu and a cerebral palsy rate of 14.5% by one year of age. The study by Robertson et al which followed children with hypoxic ischaemic encephalopathy found an incidence of impairment of 16% among survivors assessed at 8 years with 42% requiring school resource room help or special classes. This review emphasises the great need for comprehensive clinical and educational assessment as these infants approach school entry to enable appropriate educational provisions to be made.

Birth defects in children with newborn encephalopathy.

This study was designed to investigate birth defects found in association with newborn encephalopathy. All possible birth defects were ascertained in a population-based study of 276 term infants with moderate or severe encephalopathy and 564 unmatched term control infants. A strong association between birth defects and newborn encephalopathy was found with defects affecting 27.5% of children with encephalopathy and 4.3% of control children (odds ratio 8.55; 95% confidence interval 5.25 to 13.91;p<0.001). In 11.8% of infants with a birth defect the defect was not diagnosed until after the newborn period, illustrating one of the difficulties in attempting to exclude infants with birth defects from studies of newborn encephalopathy. The majority of defects (89%) were not specific anomalies of the CNS. In 36.8% of children with encephalopthy who had a birth defect, the defect was considered to be the probable cause of the encephalopathy. Infants with birth defects who had encephalopathy had a poorer prognosis than those without: they were twice as likely to die by the age of 2 years and three times more likely to have cerebral palsy. This study catalogues the spectrum of birth defects associated with newborn encephalopathy and illustrates the importance of their inclusion when investigating both the aetiology and outcome of this condition.

Why is the placenta being ignored?

The relationship between the frequency of published recommended indications for placental pathological examination and the frequency of requests for such examination in a population-based study of term newborn encephalopathy was examined. Only 11.2% of placentas among 276 case infants and 0.7% of placentas among 564 term control infants were examined. Using the criteria set out in a consensus statement by the American College of Pathologists, all 276 cases fulfilled multiple maternal, fetal and placental indications for placental examination. Furthermore 43.3% of control infants fulfilled at least one criterion. Of the 25 case placentas that underwent pathological review, 16 were reported as having no diagnostic abnormality Six cases (24%) showed clinically important findings: four had evidence of infection, one had multiple chorangiomata and one had thrombosis and rupture of the umbilical vein. Of the three remaining placentas, one showed funisitis, one showed minor lymphohistiocytic villitis and one was from monochorionic twins. To our knowledge there are no agreed Australian guidelines for when a placenta should be submitted for pathological examination. We suggest that until guidelines based on properly designed studies are developed it may be appropriate to store all placentas for at least 72 hours. If the infant develops neurological symptoms or requires unexpected admission to a neonatal intensive care unit then placental examination may reveal important aetiological diagnostic and prognostic information.

The CART gene and human obesity: mutational analysis and population genetics.

The cocaine- and amphetamine-regulated transcript (CART) peptide is a recently characterized neuropeptide implicated in the control of appetite. We hypothesized that genetic variation in CART may contribute to human obesity. The entire coding region of CART was determined by nucleotide sequencing in 91 unrelated subjects with severe early-onset obesity. A novel amino acid change, Ser66Thr, was found in 2 probands and in 0 of 100 control subjects but did not cosegregate with obesity in family studies. Two common polymorphisms were found in the 3'-untranslated region (A1475G and deltaA1457). An effect of these polymorphisms on body composition and intermediate phenotypes related to obesity was examined in a large Caucasian population in the U.K. Neither polymorphism showed any significant relationship with obesity; however, men heterozygous for the A1475G variant had significantly lower waist-to-hip ratio (WHR), fasting plasma insulin, and fasting triglycerides. Regression analysis indicated that the effects on insulin and triglycerides were likely to be secondary to the effects on WHR. Thus, we have conducted the first systematic study of the CART gene in human obesity, and although no clear association with obesity was found, the data suggest that genetic variation in the CART locus might influence fat distribution and variables related to syndrome X.

Dominant and recessive inheritance of morbid obesity associated with melanocortin 4 receptor deficiency.

Over 20 severely obese subjects in 11 independent kindreds have been reported to have pathogenic heterozygous mutations in the gene encoding the melanocortin 4 receptor (MC4R), making this the most common known monogenic cause of human obesity. To date, the detailed clinical phenotype of this dominantly inherited disorder has not been defined, and no homozygous subjects have been described. We determined the nucleotide sequence of the entire coding region of the MC4R gene in 243 subjects with severe, early-onset obesity. A novel two-base pair GT insertion in codon 279 was found in two unrelated subjects, and four novel missense mutations, N62S, R165Q, V253I, C271Y, and one mutation (T112M) reported previously were found in five subjects. N62S was found in homozygous form in five children with severe obesity from a consanguineous pedigree. All four heterozygous carriers were nonobese. Several features of the phenotype, e.g. hyperphagia, tendency toward tall stature, hyperinsulinemia, and preserved reproductive function, closely resemble those reported previously in Mc4r knock-out mice. In addition, a marked increase in bone mineral density was seen in all affected subjects. In transient transfection assays, the N62S mutant receptor showed a responsiveness to alphaMSH that was intermediate between the wild-type receptor and mutant receptors carrying nonsense and missense mutations associated with dominantly inherited obesity. Thus MC4R mutations result in a syndrome of hyperphagic obesity in humans that can present with either dominant or recessive patterns of inheritance.

Maternal thyroid disease: a risk factor for newborn encephalopathy in term infants.

Two previously published studies of term newborn encephalopathy showed that maternal thyroid disease to be a risk factor. From these studies we identified 13 case and three control mothers with thyroid disease and investigated them further. The majority of affected case mothers had idiopathic or autoimmune hypothyroidism. Compared with control mothers, case mothers had fewer thyroid function tests in pregnancy, were more likely to remain on the same dose of medication throughout pregnancy and to have experienced other pregnancy complications. The association between maternal thyroid disease and encephalopathy may be the result of a series of different causal pathways, some of which are suggested by our data.

Primary dysmenorrhea in young Western Australian women: prevalence, impact, and knowledge of treatment.

PURPOSE: To explore the prevalence of dysmenorrhea among senior high school girls in Perth, Western Australia, its impact on school, sporting, and social activities, students' management strategies, and their knowledge of available treatment. METHODS: A total of 388 female students in Grades 11 and 12 at three metropolitan secondary schools completed an anonymous questionnaire administered during class time. The following definition of dysmenorrhoea was used: any type of pain or discomfort associated with menstrual periods including cramps, nausea, and headaches. RESULTS: The reported prevalence of dysmenorrhea among these girls was 80%; 53% of those girls with dysmenorrhea reported that it limited their activities. In particular, 37% said that dysmenorrhea affected their school activities. The most common medication used by those reporting dysmenorrhea was simple analgesics (53%), followed by nonsteroidal anti-inflammatory drugs (NSAIDs), used by 42%. More than a quarter of respondents (27%) were unaware that NSAIDs were a possible treatment option for dysmenorrhea. CONCLUSION: The prevalence and impact of dysmenorrhea on Grade 11 and 12 girls is high, and they lack knowledge of and experience with effective treatment. Health education measures are needed in this area to prevent unnecessary suffering and interruption to school routine.

Group B streptococcus infection, not birth asphyxia.

This case illustrates 2 main points. Firstly, fetal infection can mimic exactly both the immediate and delayed signs of perinatal asphyxia. Secondly, the placenta may hold the key to the diagnosis of sepsis which may be made difficult in the neonate by labour ward practices such as the use of intrapartum and immediate newborn antibiotics. We strongly support the recommendation that newborn blood and fetal membrane cultures should always be obtained in babies with a diagnosis of 'intrapartum asphyxia and fetal distress' (1). To this we would add the recommendation that placental histology be performed in these circumstances.

Antepartum risk factors for newborn encephalopathy: the Western Australian case-control study.

OBJECTIVE: To ascertain antepartum predictors of newborn encephalopathy in term infants. DESIGN: Population based, unmatched case-control study. SETTING: Metropolitan area of Western Australia, June 1993 to September 1995. SUBJECTS: All 164 term infants with moderate or severe newborn encephalopathy; 400 randomly selected controls. MAIN OUTCOME MEASURES: Adjusted odds ratio estimates. RESULTS: The birth prevalence of moderate or severe newborn encephalopathy was 3.8/1000 term live births. The neonatal fatality was 9.1%. The risk of newborn encephalopathy increased with increasing maternal age and decreased with increasing parity. There was an increased risk associated with having a mother who was unemployed (odds ratio 3.60), an unskilled manual worker (3.84), or a housewife (2.48). Other risk factors from before conception were not having private health insurance (3.46), a family history of seizures (2.55), a family history of neurological disease (2.73), and infertility treatment (4.43). Risk factors during pregnancy were maternal thyroid disease (9.7), severe pre-eclampsia (6.30), moderate or severe bleeding (3.57), a clinically diagnosed viral illness (2.97), not having drunk alcohol (2.91); and placenta described at delivery as abnormal (2.07). Factors related to the baby were birth weight adjusted for gestational age between the third and ninth centile (4.37) or below the third centile (38.23). The risk relation with gestational age was J shaped with 38 and 39 weeks having the lowest risk. CONCLUSIONS: The causes of newborn encephalopathy are heterogeneous and many of the causal pathways start before birth.

Intrapartum risk factors for newborn encephalopathy: the Western Australian case-control study.

OBJECTIVE: To identify intrapartum predictors of newborn encephalopathy in term infants. DESIGN: Population based, unmatched case-control study. SETTING: Metropolitan area of Western Australia, June 1993 to September 1995. SUBJECTS: All 164 term infants with moderate or severe newborn encephalopathy; 400 randomly selected controls. MAIN OUTCOME MEASURES: Adjusted odds ratio estimates. RESULTS: The birth prevalence of moderate or severe newborn encephalopathy was 3.8/1000 term live births. The neonatal fatality was 9.1%. Maternal pyrexia (odds ratio 3.82), a persistent occipitoposterior position (4.29), and an acute intrapartum event (4.44) were all risk factors for newborn encephalopathy. More case infants than control infants were induced (41.5% and 30.5%, respectively) and fewer case infants were delivered by caesarean section without labour (3.7% and 14.5%, respectively). Operative vaginal delivery (2.34) and emergency caesarean section (2.17) were both associated with an increased risk. There was an inverse relation between elective caesarean section (0.17) and newborn encephalopathy. After application of a set of consensus criteria for elective caesarean section only three (7%) eligible case mothers compared with 33 (65%) eligible control mothers were sectioned electively. Of all the case infants, 113 (69%) had only antepartum risk factors for newborn encephalopathy identified; 39 (24%) had antepartum and intrapartum factors; eight (5%) had only intrapartum factors; and four (2%) had no recognised antepartum or intrapartum factors. CONCLUSIONS: The causes of newborn encephalopathy are heterogeneous and many relate to the antepartum period. Elective caesarean section has an inverse association with newborn encephalopathy. Intrapartum hypoxia alone accounts for only a small proportion of newborn encephalopathy. These results question the view that most risk factors for newborn encephalopathy lie in the intrapartum period.

Creatine kinase kinetics, ATP turnover, and cardiac performance in hearts depleted of creatine with the substrate analogue beta-guanidinopropionic acid.

Rats were fed a diet containing 1% of the creatine substrate analogue beta-guanidinopropionic acid for 6-10 weeks. 31P-NMR investigation of isolated, glucose-perfused working hearts showed a 90% reduction in [phosphocreatine] from 22.2 to 2.5 mumol/g dry wt in guanidinopropionic acid-fed animals but no change in [Pi], [ATP], or intracellular pH. The unidirectional exchange flux in the creatine kinase reaction (direction phosphocreatine----ATP) was measured by saturation transfer NMR in hearts working against a perfusion pressure of 70 cm of water. This exchange was 10 mumol/g dry wt per s in control hearts and decreased 4-fold to 2.5-2.8 mumol/g dry wt per s in hearts from guanidinopropionic acid-fed animals. Oxygen consumption and cardiac performance were measured in parallel experiments at two perfusion pressures, 70 and 140 cm. No significant differences were observed in oxygen uptake or in any of the performance criteria between hearts from control and guanidinopropionic acid-fed rats at either workload. Assuming an ADP:O ratio of 3, the oxygen consumption measurements correspond to ATP turnover rates of 4.2-7.8 mumol/g dry per s. These rates are 1.5-3-times greater than the rate of the phosphocreatine----ATP exchange in hearts from guanidinopropionic acid-fed rats. These data suggest that phosphocreatine cannot be an obligate intermediate of energy transduction in the heart.

A phosphorus-31 nuclear magnetic resonance study of effects of altered thyroid state on cardiac bioenergetics.

We have used 31P nuclear magnetic resonance (NMR) techniques to characterize bioenergetic changes in the Langendorff-perfused rat heart accompanying alterations in thyroid state. Cytosolic phosphocreatine and inorganic phosphate concentrations changed significantly in both the hypo- and hyperthyroid groups compared to controls; the calculated phosphorylation potential [( ATP]/[ADP][Pi]) increased by 60% in hypothyroidism and decreased by 60% in hyperthyroidism relative to the euthyroid value of 47 X 10(3) M-1. Creatine phosphokinase (CPK) and mitochondrial ATP synthase rates were measured in the intact tissue using a saturation-transfer NMR method. There were no significant differences in the measured fluxes through the CPK reaction among the three groups (4.24 +/- 1.00 mM X sec-1 for the euthyroid group). Although O2 consumption increased by 46% in hearts from hyperthyroid animals, no change in the measured mitochondrial ATP synthase flux was observed compared to the euthyroid flux of 1.05 +/- 0.11 mM X sec-1. These results suggest that the apparent in situ P/O ratio of mitochondria in hearts from hyperthyroid animals is reduced relative to that in euthyroid controls.

The effect of beta blockade and partial agonist activity during myocardial ischemia.

In this study, we have investigated the importance of partial agonist activity during myocardial ischemia by comparing the effects of equiblocking doses of oxprenolol, which possesses partial agonist activity, to propranolol which does not. In the isolated, globally ischemic (low-flow) rat heart, when propranolol or oxprenolol was added alone during the ischemic period, only propranolol reduced enzyme leakage relative to control. However, when the hearts were perfused (10 min) prior to ischemia with these drugs, both beta blockers caused a significant reduction in enzyme leakage. Under conditions of enhanced sympathetic drive (in the presence of 0.01 microM isoproterenol), both beta blockers reduced enzyme leakage to differing extents. In hearts with low sympathetic drive (reserpine pretreatment), enzyme leakage was unaffected by propranolol and exacerbated by oxprenolol. The results of this study suggest that oxprenolol and propranolol influence ischemic damage to differing extents and that this difference is due to partial agonist activity. Also, the protective action of all beta-blocking compounds depends greatly on the background level of sympathetic drive.

Long-term beta-blockade: prolonged protective action on the ischaemic myocardium.

In this study we have assessed the possibility that long-term beta-blockade may offer additional protection against myocardial ischaemia that is separate from that afforded by acute beta-blockade. In addition, the effect of intrinsic sympathomimetic activity (ISA) on this additional protection was also investigated. Equipotent doses (4 mg . kg-1 body wt . day-1) of oxprenolol (possessing ISA) or propranolol (without ISA) were administered orally to rats for 3 weeks. Hearts were excised an perfused as isolated "working" heart preparations at variable times after the last dose. Hearts excised on the final day of drug administration showed significantly higher basal functional performance compared with untreated hearts. After 30 min reduced flow ischaemia (in the presence of exogenous catecholamine drive) hearts were aerobically reperfused and functional recovery measured. In both chronically beta-blocked groups, at times when plasma drug levels were undetectable, the number of hearts that recovered function and the cellular levels of creatine phosphate and glycogen were significantly increased. In addition, hearts from the oxprenolol-treated group perfused on the final day of drug administration, exhibited a greater recovery of heart rate compared with both propranolol treated and untreated groups. These results indicate that secondary consequences of long-term beta-blockade are beneficial to the ischaemic myocardium in the presence of high catecholamine drive. In addition, the possession of ISA by oxprenolol offered some advantages in terms of post-ischaemic functional recovery.

Beta-blockade and ischaemic injury: effects of partial agonist activity.

In this study we have attempted: firstly to assess the extent to which the presence of partial agonist activity in a beta-blocking compound and/or sympathetic drive, influence ischaemic injury, and secondly to determine if any of the observed differences are due to changes in contractile activity. In the isolated, globally ischaemic (low flow) rat heart, oxprenolol (which possesses partial agonist activity) did not reduce creatine kinase leakage to the same extent as propranolol (no partial agonist activity) regardless of the background level of catecholamine drive. However, increasing background catecholamine drive increased the relative protection against enzyme leakage, of both beta-blockers. Under conditions of zero contractile activity (high K+ - medium) neither beta-blocker reduced enzyme leakage. Thus at equi-blocking doses oxprenolol and propranolol reduce enzyme leakage to different extents and the lesser protection afforded by oxprenolol is likely to be attributed to the presence of partial agonist activity. In addition, the reduction in enzyme leakage caused by both these compounds is due to reductions in contractile activity.