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Biomedical subjects

L P Brown

Publications and source records attributed to L P Brown.

At least 19 recordsLinked to original sources
PubMed1992

Breastfeeding and jaundice: cause for concern?

Jaundice occurs in 50-75% of newborn infants and is noted to occur more frequently and with greater severity in breastfed infants. However, despite years of investigation of this common problem, many aspects of neonatal jaundice in healthy breastfed infants remain unexplained. Knowledge of the types, pattern, and causes of jaundice in healthy breastfed neonates is reviewed, and the potential effect of treatment options is discussed. Practices and interventions used by health care professionals that may decrease the duration of breastfeeding and increase the incidence and severity of jaundice experienced by newborns also are explored.

Adult↗
PubMed1991

Home visits for pregnant diabetic women: environmental assessment as a basis for nursing intervention.

A major goal in management of pregnancies complicated with diabetes is strict control of blood glucose levels. After glucose control is achieved, home visits by the Perinatal Clinical Nurse Specialist (PCNS) who has advanced knowledge and skills in the management of high risk pregnancies can be invaluable. The PCNS systematically assesses the client's environment and its effects upon the client's ability to carry out the many therapeutic self-care demands associated with the diabetic pregnancy. These include the client's ability to: identify and act upon episodes of hypo- or hyperglycemia, monitor blood glucose levels, self-administer insulin, self-monitor fetal activity, and identify and act upon danger signs in pregnancy and signs of labor. The PCNS, by assessing and planning within the framework of the client's environment, facilitates continued control of diabetes as the woman makes the transition from the hospital to the home and/or work environment.

Female↗
PubMed1990

Correlations between bioassay dose-level, mutagenicity to Salmonella, chemical structure and sites of carcinogenesis among 226 chemicals evaluated for carcinogenicity by the U.S. NTP.

Bioassay dose-level data for 226 chemicals unequivocally defined as carcinogens or non-carcinogens in mice and/or rats by the U.S. NTP have been standardized to gavage equivalent dose-levels according to a modification of the methods of Gold et al. Correlations by bioassay dose-level with chemical structure, mutagenicity to Salmonella, sites of carcinogenesis and extent of trans-species activity have been studied. The data obtained add further weight to the proposition that two classes of rodent carcinogen are present in the NTP database--genotoxic carcinogens that occur predominantly in the dose range 20-800 mg/kg and putative non-genotoxic carcinogens that are equally distributed over the dose range less than 20- greater than 3000 mg/kg. The latter carcinogens are characterized by the lack of structural alerts to DNA reactivity, the absence of mutagenicity to Salmonella, an inability to induce tumours in 8 reference tissues and a strong tendency to be tissue and species-specific in their activity. Where comparisons can be made, the present findings for the NTP carcinogens and non-carcinogens are consistent with the recent observations by Gold et al. for a larger group of carcinogens.

Animals↗
PubMed1990

Health risk assessment of environmental exposure to trichloroethylene.

A review of the animal data showed trichloroethylene (TRI) to be of low acute toxicity. Repeated exposure showed that the target organs were the liver, and to a lesser extent, the kidney. TRI is not mutagenic or only marginally mutagenic. There is no evidence of fetotoxicity or teratogenicity. TRI is judged not to exhibit chronic neurotoxicity. Lifetime bioassays resulted in tumors in both the mouse and the rat. However, because of qualitative and quantitative metabolic differences between rodent and human, no one suitable tumor site can be chosen for human health risk assessment. In addition, of the several epidemiology studies, none has demonstrated a positive association for increased tumor incidence. A review of the health effects in humans shows TRI to be of low acute toxicity and, following chronic high doses, to be hepatotoxic. Environmental exposure to TRI is mainly via the atmosphere, while the contribution from exposure to drinking water and foodstuffs is negligible. The total body burden was calculated as 22 micrograms/day. The safety margin approach based on human health effects showed that TRI levels are well within the safety margin for the human no-observable-effect level (10,000 times lower). The total body burden represents a risk of 1.4 X 10(-5) by linearized multistage modeling. Therefore, by either methodological approach to risk assessment, the environmental occurrence of TRI does not represent a significant health risk to the general population or to the population in areas close to industrial activities.

Animals↗
PubMed1990

The effect of fluoride consumption and social class on dental caries in 8-year-old children.

School dental service data indicate that whilst Melbourne eight-year-old children had worse dental health than similar children in the Geelong area in 1979, the situation in 1985 was the reverse. In order to investigate this, and determine the effects of socio-economic level (SEL), residential history, and fluoride history on dental caries status, 208 eight-year-old children in the Melbourne area and 209 eight-year-old children in the Geelong area were examined for dental caries. A questionnaire was administered to gain details of subjects' exposure to water and supplement fluorides. The SEL of the subjects' school was used in place of individual SEL. A high proportion (46 per cent) of Geelong subjects used a fluoride supplement at some stage, but few continued this for most of their life. Residential history was important, with 2.4 per cent of the Melbourne subjects living most of their life in a nonfluoridated area and 3.4 per cent of Geelong subjects living most of their life in a fluoridated area. There was a significant difference between the dmft in Melbourne and Geelong when only children who had lived all their life in the city in which they were examined and did not use a fluoride supplement were included. A large part of this difference is attributed to water fluoridation in Melbourne. A substantial number of children would benefit from fluoridation of the reticulated water supply in Geelong, particularly those in the lower social classes.

Analysis of Variance↗
PubMed1990

Transcutaneous bilirubinometer: intermeter reliability.

This study examined intermeter reliability on two transcutaneous bilirubinometers on 30 white prephototherapy infants between 36 and 42 weeks' gestation with birthweights greater than 2500 g. All infants were screened with both meters, on the forehead, within a 5-minute period. Meter readings were taken within 30 minutes following infant heelstick for serum bilirubin. The Pearson correlations between serum bilirubin and jaundice meter measurements were .75 for meter 1 and .76 for meter 2. The correlation between jaundice meter indices from the two meters was .87, leaving 13% of the variance in one meter not accounted for by the correlation with the other meter. An examination of the differences between the two meters revealed that in the upper range (greater than or equal to 16) meter 1 was always higher than meter 2 by, on the average, 2.6 points (SD = 1.3). In readings of 15 or less, the differences between the meters were inconsistent. Additionally, in 16 of 30 cases, the action levels from the two meters led to the same conclusion; in the remaining 14 cases, meter 1 gave a positive reading (indicating the need to determine serum bilirubin) while meter 2 gave an equivocal reading (indicating user discretion in deciding whether serum bilirubin should be determined). These data indicate that each meter should be individually evaluated to determine action indices, and that jaundice meters should not be used interchangeably on the same infant.

Bilirubin↗
PubMed1989

Do rats comply with EPA policy on cancer risk assessment for formaldehyde?

Formaldehyde has been shown to cause nasal squamous cell carcinomas in the rat following 2-year inhalation exposure. The incidence of this tumor in a historical data base of 16,794 rats was nil, indicating that it is a rare spontaneous tumor. Five different mathematical extrapolation models were applied to the rat nasal tumor data to produce estimates at 10(-4) risk (the size of the historical data base) of between 3.232 and 0.003 ppm formaldehyde depending on the model and choice of maximum likelihood estimate or lower confidence limit values. Assuming that an ambient level of 0.07 ppm formaldehyde exists in a rat house, the multistage linear model did not predict correctly within the observed data. The EPA policy model (multistage third order) was not inconsistent with the observed data (P = 0.259). However, the unit risk, derived from this form of modeling, shows considerable inconsistency, at ambient levels of formaldehyde, when compared to observed incidences of nasal tumors in the general human population. It is proposed that the multistage models are inappropriate, and that caution should be exercised in the extrapolation of highly nonlinear animal tumor data.

Animals↗
PubMed1989

Changing caries experience and risk factors in five- and six-year-old Melbourne children.

Recent studies have shown a decline in the caries experience in Australian children. It has also been shown that a number of socio-demographic variables are associated with risk of caries experience. The aims of the present study were to identify changes in caries experience and the association of socio-demographic variables with risk of caries experience in five- and six-year-old children over the period 1977 to 1985. In 1985, a sample of 174 children resident in the municipality of Brunswick, a suburb of Melbourne, was examined. A similar sample was drawn from the same area in 1977. The percentage of children caries-free had greatly increased, while caries experience had decreased. Parental birthplace, occupation and ethnicity were associated with caries experience in 1977 and were used to control for socio-demographic changes in the samples between the two survey times. In 1985 exposure to water fluoridation was also associated with caries experience. The study highlighted the improvement in dental health of five- and six-year-old children in Melbourne since 1977 and the consistency of associations between socio-demographic variables and 'at risk' children.

Child↗
PubMed1989

Teratogenicity of phenylhydantoins in an in vitro system: molecular orbital-generated quantitative structure-toxicity relationships.

1. The ability of 20 mono- and di-phenylhydantoin derivatives to inhibit differentiation of rat embryo mid-brain and limb bud cells in culture has been used as an index of the teratogenic hazard represented by these compounds. 2. Molecular orbital calculations on these compounds, using the MINDO-3 (modified intermediate neglect of differential overlap) and CNDO-2 (complete neglect of differential overlap) methods, were combined with indices of teratogenicity in the two cell types, to generate a coherent structure-toxicity relationship. 3. Teratogenicity correlated with frontier orbital electron density of the N1 hydantoin ring atom (HOMO-N1) in a sub-series of 12 monophenylhydantoins, whereas the corresponding toxicity for both mono- and di-phenylhydantoins related more to the molecular polarizability (alpha mol) of the molecule. 4. Furthermore the same structural parameter (alpha mol) exhibited a parallelism with log P values of these 20 compounds, indicating the importance of lipophilicity in the toxicity of these compounds. 5. Overall, the data emphasize the ability of electronic structural calculations to identify chemical descriptors of toxicity.

Animals↗
PubMed1989

Developing a program grant for use in model testing.

Early discharge is becoming a practice as well as a goal for the acute care institution. It is essential that nursing investigate the effects of this shift in the care delivery site from the acute care institution to the home and community. Brooten et al. describe a research model designed to do just that. Transitional care, as this team calls it, may soon become familiar jargon in community health care.

Clinical Nursing Research↗
PubMed1988

Children's judgments of event upsettingness and personal experiencing of stressful events.

Five-hundred and three urban and suburban 4th- to 6th-grade schoolchildren judged event upsettingness and reported the occurrence of 22 life events. Judgments of event upsettingness ranged considerably, some corresponding to, others differing from, adult judgments. Children reported experiencing an average of seven events during their lifetimes. Girls judged events to be more upsetting than boys, and fourth and fifth graders judged events to be more upsetting than sixth graders. Urban children reported having experienced more stressful events than suburban children, and sixth graders experienced more events than fourth graders.

Age Factors↗
PubMed1986

A randomized clinical trial of early hospital discharge and home follow-up of very-low-birth-weight infants.

To determine the safety, efficacy, and cost savings of early hospital discharge of very-low-birth-weight infants (less than or equal to 1500 g), we randomly assigned infants to one of two groups. Infants in the control group (n = 40) were discharged according to routine nursery criteria, which included a weight of about 2200 g. Those in the early-discharge group (n = 39) were discharged before they reached this weight if they met a standard set of conditions. For families of infants in the early-discharge group, instruction, counseling, home visits, and daily on-call availability of a hospital-based nurse specialist for 18 months were provided. Infants in the early-discharge group were discharged a mean of 11 days earlier, weighed 200 g less, and were two weeks younger at discharge than control infants. The mean hospital charge for the early-discharge group was 27 percent less than that for the control group ($47,520 vs. $64,940; P less than 0.01), and the mean physician's charge was 22 percent less ($5,933 vs. $7,649; P less than 0.01). The mean cost of the home follow-up care in the early-discharge group was $576, yielding a net saving of $18,560 for each infant. The two groups did not differ in the numbers of rehospitalizations and acute care visits, or in measures of physical and mental growth. We conclude that early discharge of very-low-birth-weight infants, with follow-up care in the home by a nurse specialist, is safe and cost effective.

Body Weight↗