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Biomedical subjects

B Towne

Publications and source records attributed to B Towne.

32 records · Page 2Linked to original sources
PubMed1997

Opportunities and difficulties in long-term studies of growth.

Overviews are presented of the University of Melbourne Child Growth Study and of the Fels Longitudinal Study; each of these studies had a major focus on the growth and maturation of children. Planning, study design, logistics and staffing varied between these studies, but each led to exciting research opportunities that can exist only when longitudinal data are available. There are important differences between these studies in the types of participants, ages at examinations, the variables measured, some topics of central concern, and in funding. In each study, research productivity was low in the early years, the retention of participants was a major concern, and it was necessary to maintain a balance between data collection, data management, and data analysis. More such studies are needed that focus on particular population groups and topic areas and that utilize the lessons of the past to maximize the chances of future success.

Adolescent↗
PubMed1997

Ontogenetic changes in genetic regulation of fetal morphometrics in baboons (Papio hamadryas subspp.).

It is known that different genes are expressed during ontogeny; however, it is unclear how variation in that expression is associated with changes in growth patterns. The objective of this study is to assess how genetic variation in fetal morphology changes with ontogeny in baboons. Longitudinal measures of the head and femur (60 to 180 days gestation) were available for 892 pregnancies. We used a genetic model that allowed both the genetic and environmental variances (sigma 2G and sigma 2E) to change with age and estimated genetic and environmental correlations (rho G and rho E) between measurements at different ages. The results indicate a significant increase in the genetic variance for biparietal diameter and femur length but not for head circumference and fronto-occipital diameter. The rho G estimates for all measures decreased as the age between measures increased from 0 to 120 days, indicating that different groups of genes are expressed early in gestation and late in gestation. The rho E estimates dropped rapidly from 1 to 0 for all measures, indicating temporally localized environmental influences on fetal growth. Thus fetal morphometrics are significantly heritable and those genes that influence them show age-specific expression during ontogeny.

Animals↗
PubMed1993

Genotype by sex interaction in measures of lipids, lipoproteins, and apolipoproteins.

Genotype by sex (GxS) interaction in a quantitative trait indicates that the sexual dimorphism exhibited in that trait is heritable. GxS interaction has implications for the modeling of traits in segregation analyses and for the assessment of disease risk in males and females. Thirteen quantitative measures of lipids, lipoproteins, and apolipoproteins from 203 to 301 individuals in 25 to 27 kindreds were examined for evidence of GxS interaction. These measures included serum concentrations of total cholesterol, triglycerides, LDL-C, HDL-C, apo B, and apo AI, and peak LDL particle diameter, small LDL mass, large LDL mass, IDL mass, VLDL mass, HDL3 mass, and HDL2 mass. GxS interaction was indicated for transformed values of LDL-C and small LDL mass by an additive genetic correlation between males and females significantly less than 1.0, and GxS interaction was indicated for transformed values of HDL3 mass and HDL2 mass by males and females having significantly different additive genetic variances.

Adult↗
PubMed1993

Genetic analysis of patterns of growth in infant recumbent length.

A genetic basis to growth and development has been demonstrated in many heritability studies of anthropometrics. Although such measures describe the extent of growth at particular times, they do not fully address the process of growth. We applied a three-parameter curve-fitting function to serial measures of recumbent length from 569 infants (birth to 2 years of age) in 188 families enrolled in the Fels Longitudinal Study. This yielded three growth pattern parameters that represented estimated recumbent length at birth (parameter 1), rate of growth (parameter 2), and intrinsic rate of change in growth (parameter 3). The growth pattern parameter estimates for each individual were examined in a series of genetic analyses using a maximum-likelihood method for pedigree data. Significant heritabilities were found for all three growth pattern parameters: parameter 1, h2 = 0.83 +/- 0.12; parameter 2, h2 = 0.67 +/- 0.18; and parameter 3, h2 = 0.78 +/- 0.17. In addition, genotype by sex interaction was indicated for growth pattern parameters 2 and 3, suggesting that the genes influencing rate of growth and intrinsic rate of change in growth are themselves influenced by the sex of the individual.

Anthropometry↗
PubMed1990

Long-term neurophysiologic outcome after neonatal extracorporeal membrane oxygenation.

We examined clinical and neurophysiologic measures in 10 children 4 to 9 years after neonatal extracorporeal membrane oxygenation. Electroencephalograms did not correlate with clinical or other neurophysiologic measures of interhemispheric asymmetry. By ultrasound imaging, the right internal carotid artery velocity was approximately 62% of that on the left, and right internal carotid flow was reduced by 74% (p less than or equal to 0.01), whereas an age-matched control group showed no differences. A decrease in the amplitude of the long-latency auditory and somatosensory evoked potentials was noted over the right hemisphere after left-sided stimulation compared with the left hemispheric potentials after right-sided stimulation (p less than or equal to 0.005). No significant differences in hemispheric symmetry were noted in the amplitudes for wave V of the auditory brain-stem response or in the P30 component of the middle-latency auditory evoked potentials. Likewise, latency measures of the evoked potentials were symmetric. We conclude that (1) neonatal extracorporeal membrane oxygenation is associated with long-lasting decreased right internal carotid blood flow with compensatory increased flow through the left carotid system and (2) there is a consistent reduction in the amplitude of right hemispheric long-latency evoked potentials. These latter findings may reflect redirected cerebral blood flow patterns after extracorporeal membrane oxygenation.

Blood Flow Velocity↗
PubMed1990

Generational change in skin color variation among Habbani Yemeni Jews.

The Habbani Yemeni Jews were a religious isolate in Yemen for centuries. Since a bottleneck in the late eighteenth century the population, composed of six partrilineages, has steadily grown. Isonymy analysis of Habbani genealogies reveals a significant increase in lineage endogamy by the early twentieth century, suggesting that microdifferentiation of Habbani population genetic structure along the patrilineages was occurring. We examine reflectance data from a "parental" generation of 159 individuals studied by Hulse in the 1960s and reflectance data from an "offspring" generation of 243 individuals studied by Towne in the 1980s. A greater amount of interlineage skin color differences is found in the offspring generation than in the parental generation. This finding is consistent with what is known of the evolution of Habbani population genetic structure.

Female↗
PubMed1986

Long-term use of indwelling multipurpose silastic catheters in pediatric cancer patients treated with aggressive chemotherapy.

We studied the complications related to the use of 53 multipurpose silastic catheters (MSC) placed in 46 pediatric cancer patients over a 1-year period. We documented the longest duration of catheter placement in the pediatric oncology literature. There were 7,650 Broviac days (range, 9 to 365 days; mean, 163 days) with 255 patient months of catheter use and a mean of 5.5 months per catheter. Of the 53 MSCs, 90% were Broviacs (72% adult size, 18% pediatric size) and 10% Hickman. There were 23 episodes of bacteremias or 0.31 episodes per 100 days of catheter use. Coagulase-negative staphylococci were isolated in 20% of the episodes of bacteremia. Only 34% had an absolute granulocyte count (AGC) (Polymorphonuclear cells [PMN] + band cells) less than 500 in the 23 MSCs with bacteremia. Ten percent were removed: 4% for mechanical problems, 6% for bacteremia unresponsive to appropriate antibiotic therapy. There were no deaths related to bacteremia, embolism, or vascular damage. This study demonstrated that despite the recent use of more aggressive immunosuppressive therapy, the incidence of MSC bacteremias was 43%, similar to earlier National Cancer Institute studies (39%) American Society of Clinical Oncology, (abstract C-219, 1982). Based on these findings, we have currently modified our MSC care and have recently throughout the past 6 months reduced our infectious complication rate by 50%.

Adolescent↗
PubMedDate not supplied

Adult changes in body composition are associated with changes in cholesterol levels: the Fels longitudinal study.

Serial data from 507 adult participants in the Fels Longitudinal Study were used to study relationships between average annual changes in serum cholesterol levels and annual changes in total body fat, fat-free mass, percent body fat or body mass index in men and women aged 18-45 years or 45-65 years. Average annual changes in adiposity before and after 45 years of age for men and women show statistically significant, strong, positive relationships with corresponding changes in cholesterol levels.

Adipose Tissue↗
PubMedDate not supplied

The relationship of soluble ICAM-1, VCAM-1, P-selectin and E-selectin to cardiovascular disease risk factors in healthy men and women.

BACKGROUND: Clinical studies have shown that elevated serum concentrations of cell adhesion molecules such as inter-cellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), E-selectin (ESEL) and P-selectin (PSEL) may be independent risk factors for atherosclerosis and cardiovascular disease (CVD). Less is known of the relationship of these inflammatory markers with established CVD risk factors in healthy individuals, particularly women. OBJECTIVE: The aim of this study was to examine cross-sectional relationships between the concentrations of soluble adhesion molecules (sICAM-1, sVCAM-1, sPSEL and sESEL) and smoking behaviour, body composition, blood pressure, serum lipids and physical activity in a large sample of healthy men and women, with special emphasis on interactions between smoking and other CVD risk factors. SUBJECTS: The analysis included 592 healthy white adults aged 18-82 years. RESULTS: There were no sex differences in the concentrations of sICAM-1, sVCAM-1 and sPSEL, but men had higher sESEL levels than women (p < 0.0001). Male and female smokers had higher sICAM-1 and sESEL levels than non-smokers and soluble cell adhesion molecules (CAMs) were correlated with the pack-years of cigarette smoking (r = 0.3-0.4, p < 0.0001, significant in women only). Significant independent associations were found between soluble CAMs and smoking, waist-hip ratio (WHR), blood pressure, high density lipoprotein cholesterol and total cholesterol. Furthermore, significant interaction effects were found in women, such that the relationship between CAMs and lipid concentrations and WHR were stronger in smokers than non-smokers. In conclusion, the concentration of soluble CAMs, particularly sICAM-1 and sESEL, reflect the level of established CVD risk factors in apparently healthy men and women, adding to the evidence that these factors contribute to CVD through their inflammatory effects on the vascular endothelium.

Adult↗
PubMedDate not supplied

Trend of blood group distribution among the Jirels of Nepal.

This study was undertaken to find out the trend of blood group distribution among the Jirels, a small tribe, descended from Kirat tribe and to compare with other castes within Nepal and with people of other continents. Blood group distribution (ABO grouping and Rh typing) was studied among 2093 Jirels (Male-1057 and Female-1036). The frequency of distribution of A, B, O and AB was 55.05%, 14.72%, 21.64% and 8.6% respectively. The group A was found to be most common among the Jirels where as O is most common in the world. Only 0.14%of the Jirels were was found to be Rhesus Negative (Rh -ve).

ABO Blood-Group System↗