Characterisation of rat hepatocyte monolayers for investigation of the metabolism of bile salts.

Rat hepatocyte monolayers were maintained for periods up to 24 h during which time their viability was greater than 85%. Using specific radioimmunoassays, the hepatocyte monolayers were shown to synthesise conjugated cholic, chenodeoxycholic and beta-muricholic acids. Feeding the bile salt sequestrant, cholestyramine, to donor animals increased synthesis of the major bile salt conjugates by the cells. Incubation of hepatocyte monolayers with bovine serum albumin decreased total synthesis of the three bile acids measured, but increased the amount of conjugated chenodeoxycholic acid detected. In order to test whether the effect of bovine serum albumin on bile salt synthesis was due to binding of bile salts, hepatocyte monolayers were incubated with antiserum to conjugated chenodeoxycholic acid. This treatment increased conjugated chenodeoxycholic acid production but had no effect on the other bile salt conjugates. It is concluded that the increase in conjugated chenodeoxycholic acid synthesis seen with bovine serum albumin and antiserum to conjugated chenodeoxycholic acid is caused by binding of the bile salt in the medium.

The effect of a rat plasma high-density lipoprotein subfraction on the synthesis of bile salts by rat hepatocyte monolayers.

The effect of a rat high-density lipoprotein subfraction (HDL2) on the synthesis of bile salts by rat hepatocyte monolayers prepared from rats fed a diet containing cholestyramine, was investigated. The synthesis of bile salts as measured by radioimmunoassay of conjugated cholic, chenodeoxycholic and beta-muricholic acids was significantly increased when hepatocytes were incubated with a physiological concentration (500 micrograms HDL2 protein X ml-1) of HDL2.

Smoking and the sudden infant death syndrome.

OBJECTIVE: Maternal smoking has been shown to be a risk factor for sudden infant death syndrome (SIDS). The effect of smoking by the father and other household members has not previously been examined. METHODS: A large nationwide case-control study. Four hundred eighty-five SIDS deaths in the postneonatal age group were compared with 1800 control infants. RESULTS: Infants of mothers who smoked during pregnancy had a 4.09 (95% confidence interval [CI] = 3.28, 5.11) greater risk of death than infants of mothers who did not smoke. Infants of mothers who smoked postnatally also had an increased risk of SIDS compared with infants of nonsmokers and, furthermore, the risk increased with increasing levels of maternal smoking. Smoking by the father and other household members increased the risk (odds ratio [OR] = 2.41, 95% CI = 1.92, 3.02 and OR = 1.54, 95% CI = 1.20, 1.99, respectively). Smoking by the father increased the risk of SIDS if the mother smoked, but had no effect if she did not smoke. In analyses controlled for a wide range of potential confounders, smoking by the mother and father was still significantly associated with an increased risk of SIDS. CONCLUSION: Passive tobacco smoking is causally related to SIDS.

Breastfeeding and the risk of sudden infant death syndrome.

The New Zealand Cot Death Study, a multicentre case-control study, was set up to identify risk factors associated with sudden infant death syndrome (SIDS). In the 3 years of the study there were 485 infant deaths classified as SIDS in the study areas and 1800 infants who were randomly selected as controls. Data were collected by parent interviews and from obstetric notes. A full set of data for this analysis was available from 356 cases and 1529 control infants. The relationship between length of any breastfeeding and SIDS was examined: 92% of the controls were initially breastfed compared to 86% of the cases. As time went by, cases stopped breastfeeding sooner than controls: by 13 weeks, 67% controls were breastfed versus 49% cases. A reduced risk for SIDS in breastfed infants persisted during the first 6 months after controlling for confounding demographic, maternal and infant factors. Infants exclusively breastfed 'at discharge from the obstetric hospital' (odds ratio [OR] = 0.52, 95% confidence interval (CI): 0.35-0.71) and during the last 2 days (OR = 0.65, 95% CI: 0.46-0.91) had a significantly lower risk of SIDS than infants not breastfed after controlling for potential confounders. We have shown a substantial association of breastfeeding with a lowered risk for SIDS. This supports the need for more positive promotion and active community support to further enhance the level and length of exclusive breastfeeding.

The effect of season-of-response to ISAAC questions about asthma, rhinitis and eczema in children.

BACKGROUND: To examine whether responses to questions about the lifetime prevalence and 12-month period prevalence of symptoms of asthma and allergies are affected by the season in which the questions are asked. METHODS: The international Study of Asthma and Allergies in Childhood (ISAAC) Phase One was undertaken in six New Zealand centres; in three centres the effect of season was studied. Over three school terms at least 3000 children were studied in each of two age groups per centre (6-7 years; 13-14 years), one-third in each term respectively. The ISAAC standardized written questionnaires were used to identify asthma, rhinitis and eczema symptoms. The written questionnaire in the younger age group was completed by the parent/guardian. The older age group self-completed the written questionnaire and also a video questionnaire about asthma symptoms. RESULTS: The total number of respondents was 21,437, approximately half in each age group. The season of responding had no effect on the level of response to eczema questions. For the written asthma questionnaire no season-of-response effect was present for 6-7 year olds; for 13-14 year olds there was a trend to a higher rate of positive responses by those responding in winter, but in only one question did this reach statistical significance. With the video questionnaire there was a similar trend for a higher rate of positive responses when questions were asked in winter, but this did not reach statistical significance. For rhinitis symptoms there was a statistically significant season-of-response effect in both age groups with two questions; the fewest positive responses by the winter responders. CONCLUSIONS: There was no significant effect of season-of-response to questions on eczema symptoms, and most questions on asthma symptoms. There was a season-of-response effect on responses to questions on rhinitis symptoms suggesting a recall bias relating to recency of symptoms.

Weather and the risk of sudden infant death syndrome: the effect of wind.

STUDY OBJECTIVE: To examine and identify relations between sudden infant death syndrome (SIDS) and wind, particularly the föhn wind, in Christchurch, New Zealand. DESIGN: A retrospective epidemiological study combining details of regional hourly meteorological variables and reported SIDS cases. SETTING: Christchurch, New Zealand, between 1968 and 1997 inclusively. PARTICIPANTS: All 646 infants reported as dying from SIDS within the greater Christchurch region. MAIN RESULTS: Analysis of 1968-1989 data revealed nine wind variables significantly related to SIDS. When compared with corresponding variables calculated over the 1990-1997 period, only the northerly wind on the day of death and the southerly wind three days before a SIDS death had estimated associations with similar effect size and sign. However, both these variables had confidence intervals that included unity. CONCLUSIONS: No evidence was found to suspect that föhn winds influenced SIDS occurrence. The relations identified between SIDS incidence and wind, after controlling for the effects of temperature and trend, were tenuous and relatively small. More data are necessary to substantiate whether northerly winds on the day of death or southerly winds occurring three days before a death are truly associated with SIDS. It seems that wind has little, if any effect on SIDS incidence in Christchurch.

Weather temperatures and sudden infant death syndrome: a regional study over 22 years in New Zealand.

STUDY OBJECTIVE: To examine and identify relationships between the sudden infant death syndrome (SIDS) and environmental temperature in Canterbury, New Zealand. DESIGN: A retrospective epidemiological study combining details of regional hourly temperature and reported SIDS cases. SETTING: Canterbury, New Zealand, between 1968 and 1989 inclusively. PARTICIPANTS: All infants reported as dying from SIDS within the Canterbury region. MAIN RESULTS: The SIDS incidence increased after months with prolonged colder minimum temperatures, confirming the seasonality of SIDS. After adjusting for this seasonality, days that showed little change in hourly temperature and days with warmer minimum temperatures recorded were seen to have a significantly increased the incidence of SIDS. No evidence was found for other relationships between the SIDS incidence and various measures of daily temperatures on the day of death, over the preceding eight days or between these days. Infants aged 12 weeks and over were more susceptible to SIDS on days when small hourly temperature changes were recorded than their younger counterparts; no other age differences emerged. CONCLUSIONS: This study confirmed that the incidence of SIDS is affected by seasonality and temperature on the day of death. In particular, after a prolonged period of cold minimum temperatures, infants were most at risk from SIDS on days on which either a warmer minimum temperature or little hourly variation in temperature were recorded. No other daily or lagged daily temperature factor (lagged up to eight days before the day of death) was statistically associated with the SIDS incidence. It is suspected that the inconsistent previously published lag effect findings actually describe some other phenomenon such as parental behaviour or infant thermoregulation.

Smoking during pregnancy: how reliable are maternal self reports in New Zealand?

OBJECTIVE: To determine the reliability of self reports of smoking during pregnancy. METHODS: Residual sera from early and late antenatal blood samples were tested for cotinine for all pregnancies over a six month period. Over an overlapping 12 month period, a postal questionnaire on smoking was also sent to all new mothers (n = 4857) when their baby was 4-8 weeks old. Smoking status from obstetric booking notes was also obtained. RESULTS: The cotinine-validated smoking prevalence was 31.3% for the first trimester and 27.7% for the third trimester. Questionnaire self reported prevalences were 19.2% and 15.7% for the first and third trimesters respectively, and 18.9% for obstetric booking. Of cotinine-validated smokers, 22% denied smoking-self deceivers. Of mothers who replied to the questionnaire, a half appeared to systematically under report the amount they smoked. CONCLUSIONS: Nearly a quarter of smoking pregnant women did not report smoking. Moreover, of those who did, the amount smoked was often under reported. This tendency to under report may rise as pressures to stop smoking increase. Accurate measures of smoking prevalence in pregnant women will require objective testing.

Sudden infant death syndrome in New Zealand: are risk scores useful? New Zealand National Cot Death Study Group.

STUDY OBJECTIVE: To evaluate the Christchurch, Invercargill, Dunedin (CID) and Oxford record linkage study (ORLS) risk scores in five regions of New Zealand and examine the effect of risk factors for sudden infant death syndrome (SIDS), such as prone sleeping position, maternal smoking, breast feeding, measures of illness, the use of antenatal classes, community health care, and medical services on a high and low risk group delineated by the CID score. DESIGN: This was a case-control study of infants dying of SIDS. SETTING: Both the cases and controls were born in one of five health districts in New Zealand and their parents were interviewed between 1 November 1987 and 31 October 1990. PARTICIPANTS: The cases were 485 infants who died of SIDS. The controls were a random sample drawn from the same five regions in which the cases were born, chosen so that their age on the day on which they were interviewed was similar to the age at death of the cases. Risk scores were calculated for 387 case and 1579 controls. MEASUREMENTS AND MAIN RESULTS: Using the recommended cut off points the sensitivity and specificity of the CID and ORLS were found to be similar to those described for other samples. The differences among the regions were significant. There was, however, no evidence that the association between SIDS and the risk factors considered was different in the high and low risk groups delineated by the CID score. The relative attributable risk for smoking was 32.3% in the high risk group. The excess risk that could be attributed to a different prevalence of any of the other risk factors in the high risk group was small when compared with the low risk group. CONCLUSIONS: Health care resources should be spent on promoting and evaluating good child care practices for all, rather than identifying and promoting special interventions for those in the high risk category.

Essential data derived from biological variation for establishment and use of lipid analyses.

The analytical and biological components of variation of total cholesterol, high density lipoprotein (HDL) cholesterol, HDL3 cholesterol, HDL2 cholesterol and apolipoproteins A-I and B in serum were assessed in 12 apparently healthy individuals. All analytes showed marked individuality and therefore conventional population based reference intervals are of little use. The differences required for serial results to have changed significantly for these assays were calculated. The data presented confirm that the assays studied have limited value in screening the general population.

A biochemical prevalence study of smoking in pregnancy for a cross-section of women in Christchurch, New Zealand.

OBJECTIVE: To biochemically measure and compare the prevalence of maternal smoking by trimester in a cross-section of pregnant women residing in Christchurch, New Zealand, during 1997. METHODS: Residual sera from routinely collected blood samples drawn in early and late pregnancy over a 12-month period, 1 January 1997 to 31 December 1997, was accumulated and anonymously assayed. Cotinine levels were measured by an ELISA test with a result greater than 14 ng/mL indicative of active smoking. RESULTS: Analysis was conducted upon 4,178 samples collected from 3,082 women. Adjusted cotinine validated smoking rates in the first, second and third trimesters were 26.8% (95% CI 24.5-29.2%), 25.0% (95% CI 22.3-27.8%) and 23.0% (95% CI 20.8-25.2%), respectively. This represents an absolute reduction in smoking rates of 4.7% (p = 0.02), 6.6% (p = 0.04) and 3.8% (p = 0.04) for the first, second and third trimesters, respectively, among pregnant women in Christchurch since 1994. CONCLUSION: Smoke reduction and cessation programs implemented locally and nationally have been effective in significantly reducing the biochemically measured prevalence of maternal smoking in pregnancy within a three-year period. IMPLICATIONS: Cigarette smoking during pregnancy is an important yet preventable factor affecting rates of prenatal, perinatal and paediatric morbidity and mortality. Reliable and repeated surveys of pregnant women are necessary to accurately measure changes in the maternal smoking prevalence and determine the efficacy of smoke reduction and cessation programs.

Deterministic properties of apnoeas in an abdominal breathing signal.

The paper describes a general set of properties that represent most apnoeas as found in an abdominal breathing signal. An apnoea is a pause in breathing during sleep, and only central apnoeas in infants are considered. Human experts are consulted to determine what properties of the signal they use to recognise apnoeas. A set of deterministic, or shape, properties is developed to represent expert opinion. An apnoea is modelled as a flat region with four properties: flatness, duration, thinness and smoothness. Mathematical descriptions of each property are formulated that discriminate between apnoea and non-apnoea events, and each description is tested for discrimination and independence. The average power of discrimination is 24% +/- 16% and the average correlation coefficient is 0.28 +/- 0.16. Applications include scoring apnoeas for sleep studies and developing standard definitions of apnoeas.

Postneonatal mortality in Christchurch.

The pattern of postneonatal mortality over the past 16 years in Christchurch and New Zealand is described. In Christchurch the postneonatal rate has risen from about four to eight per 1000 live births over this time, while for the rest of New Zealand the rate has been stable at about six. This rise has been due to an increasing number of cot deaths. The reason for this is unknown. Increased child health surveillance may reduce these deaths.

Who comes to a paediatric medical outpatient clinic?

A clinical audit was undertaken of all new patients (first referral) to a paediatric outpatient department over a six month period. There was a total of 542 children, of whom 59% were referred by a general practitioner and the remainder by paediatricians or other consultants. The conditions for which general practitioners most frequently referred children were cardiac murmurs and urinary tract problems, whereas respiratory disease, especially asthma, and hip and orthopaedic conditions were the common referrals from the specialists. Forty-four percent of general practitioner referrals were seen only once and then discharged, and there was a very low level of cross-referral to other disciplines.

Immunisation timeliness for a birth cohort in Christchurch. Christchurch Immunisation Coordination Study Group.

AIMS: To determine whether New Zealand's goals for immunisation coverage are being met in Christchurch and to assess whether scheduled vaccinations are being delivered in a timely fashion. METHODS: A cohort of all infants born in Christchurch during June, July and August 1995 were matched with immunisation benefit claim information for the 6-week, 3-month, 5-month and 15-month immunisation events. Those with incomplete reports were traced for amendment or verification of their immunisation status. RESULTS: The cohort contained 1002 infants. The full complement of scheduled immunisations was delivered to an estimated 95.8% (95% CI: 94.5, 97.2) of infants within the cohort by two years of age. Infants who presented late for their 6-week immunisation visits were significantly more likely to be late for their next visits (chi 2 log rank = 8.2, df = 1, p < 0.01), as were those late for their 3-month visits (chi 2 = 20.9, df = 1, p < 0.01), and their 5-month visits (chi 2 = 52.5, df = 1, p < 0.01). Infants were significantly less likely to receive their full complement of immunisations by two years of age if they presented late for their 6-week (Fisher's exact test, p = 0.01), 3-month (p < 0.01) or 5-month (p = 0.01) immunisation visits. CONCLUSIONS: The Immunisation 2000 target of 95% full immunisation coverage by two years of age was met by this cohort. However, infants who were late for any immunisation visits were more likely to be late for subsequent visits and incompletely vaccinated by two years of age, compared to those infants who presented on time.

Children's diets: what do parents add and avoid?

An interview was carried out, using a standard questionnaire, with the parents of 103 children attending as new patients to a medical paediatric outpatient clinic. This interview was designed to determine the extent of deliberate additions and avoidances to their children's diets. Some specific alteration to the diet was seen in 48 children. There were 38 avoidances and 20 additions of some form of food or mineral substance. In 10 children there were both additions and avoidances. Avoidance of a foodstuff, most commonly food additives, was either for a particular illness or health belief. Dairy products and meats were the next most frequently avoided substances. Additions to the diet were predominantly vitamins and minerals. The sources of dietary advice were the media, mainly magazines and books, and family members. Medical influence on dietary alterations was small.

Changes to infant sleep practices in Canterbury.

AIM: "Reducing the risk" is a public health primary initiative to minimise the incidence of Sudden Infant Death Syndrome (SIDS) in New Zealand. A number of SIDS risks relate to infant sleep practices. We describe current prevalences of these practices. METHODS: A cohort of Canterbury mothers delivering live infants during May 1997 (n = 411) were mailed a questionnaire in July surveying their infant's sleep practices. Survey results were compared to results derived from the Canterbury control infant component of the 1987-90 New Zealand Cot Death Study (NZCDS) (n = 174). Those mothers using either plastic or rubber mattress covers (n = 63) were issued a subsequent questionnaire pertaining to this mattress-wrapping practice. RESULTS: Completed questionnaires were returned by 274 (66.7%) mothers. Room sharing with mother was usual for 133 (48.5%) infants, no different from the 94 (54.0%) recorded in the NZCDS (chi 2 = 5.6, df = 2, p = 0.06). However, of those infants sharing a room with their mother, 101 (75.9%) slept in their own bed compared to 46 (48.9%) in the NZCDS (chi 2 = 57.0, df = 2, p < 0.01). Only 8 (2.9%) infants were regularly placed prone to sleep, considerably fewer than the 69 (39.7%) reported in the NZCDS (chi 2 = 100.1, df = 1, p < 0.01). Mattress-wrapping with plastic (14.6% vs. 4.0%; chi 2 = 12.8, df = 1, p < 0.01) and rubber (8.4% vs. 3.4%; chi 2 = 4.4, df = 1, p = 0.04) has significantly increased since the NZCDS. Results from the subsequent questionnaire, completed by 42 (66.7%) respondents, indicated that most, 25 (59.5%), wrapped their infant's mattress to stop soiling. Less than half, 18 (42.9%), wrapped the mattress for the "safety of their baby". CONCLUSION: The "non-prone sleeping" campaign has been successful in Canterbury. Most infants are now routinely placed non-prone for sleep. Of those infants sharing a room with their mothers, an increased proportion is sleeping in separate beds. The use of "drycot" under-blankets and sheepskins has diminished. While impermeable mattress-wrapping usage has significantly increased, over three-quarters of Canterbury mothers did not use plastic or rubber mattress-covers on their infant's beds.

Childhood asthma: what do parents add or avoid in their children's diets?

The parents of 100 children with chronic asthma completed a standard questionnaire designed to determine the extent of deliberate addition and avoidance of items in their children's diets. Forty-seven percent of the parents had added or deleted substances from their child's diet because of the child's asthma or a combination of asthma and another condition. This was predominantly the avoidance of dairy products, additives and eggs. The basis of dietary decisions was said to be self engendered in the main, but the family circle and the media, were stated to be common sources of advance and influence. Professional advice in the form of dietetic and medical influence was minimal. This lack of professional influence may be a reflection upon the controversial status of diet and asthma. While this exists parents may try this dietary option in the hope of therapeutic success.

Who comes back to a paediatric outpatient clinic?

Over a four week period, 498 children had appointments to be seen again at a paediatric medical outpatient clinic. 15.8% of the patients did not keep their appointments. The three most common types of disorder accounting for over half the consultations were asthma, neurological/developmental problems and genitourinary conditions. Over half (57%) had been referred within the previous two years, and only 29% had been seen for three or more years. Involvement with other medical and paramedical specialists occurred in 55%. This reflected the multidisciplinary management approach for the longer term patients. Only 14 new such referrals were generated as a result of the consultations over the four week study period. The work of the clinic was concerned with relevant chronic disease.

Infant feeding patterns in Canterbury.

AIM: To examine infant feeding patterns during the first 6 months of life in Canterbury. METHODS: A random sample of 10% of all births over a 12 month period in Canterbury was taken from birth notifications (n = 520). Information on the type of feeding was recorded prospectively at three time periods and extracted from available Plunket nursing notes. The participation rate was 81%. Data from nonparticipants on the method of feeding at discharge was obtained from obstetric records. RESULTS: Overall, 90.7% were breastfed at discharge. There was no difference between breastfeeding rates of the participants (91%) compared to the nonparticipants. For participants, 88% were exclusively breastfed at discharge which steadily declined to 36% at 24 weeks. However, some breastmilk was still being given to 70% at 24 weeks. CONCLUSION: Breastfeeding rates are good in comparison to other nations. However, there is room for improvement particularly maintaining exclusive breastfeeding to at least four months. This could be stimulated by the Baby Friendly Hospital Initiative and the fostering of a baby friendly environment to further support and promote breastfeeding in the community.