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Biomedical subjects

E F Harris

Publications and source records attributed to E F Harris.

84 records · Page 5Linked to original sources
PubMed1980

Dental asymmetry as a measure of environmental stress in the Ticuna Indians of Colombia.

The magnitude of fluctuating dental asymmetry is reported for a marginally Westernized, horticultural Indian group, the Ticuna of the Region Amazonas, Colombia. Asymmetry is lower than in other Amerindian and Eskimo groups reported to date, which accords with the adequacy and reliability of traditional food sources and complements the claim that protein intake is at or above minimum requirements. Partitioning the variation by sex, arcade, dimension, and tooth discloses several statistically significant effects. Among these: 1) females are proportionately more asymmetric than males; 2) maxillary teeth are more asymmetric than their mandibular counterparts; 3) the mesiodistal dimension is less canalized than buccolingual width in the maxilla, but is more asymmetric in the mandible; and 4) the pattern of asymmetry corresponds closely with the morphogenetic gradients within each tooth field, suggesting that bilaterality provides an additional measure for disclosing underlying genetic and ontogenetic patterns in the dentition.

Adolescent↗
PubMed1980

Complex segregation analysis of Carabelli's trait in a Melanesian population.

A complex segregation analysis was performed on Carabelli's trait on the upper first molar utilizing 358 nuclear families from the Solomon Islands of Bougainville and Malaita. Simultaneous estimation of three sources of variation by the method of maximum likelihood demonstrates a significant effect of shared sibling environment which accounts for over 19% of the variance in liability for the trait. In addition, a statistically significant major gene influence is discussed and suggestions for quantifying individual liability levels for this and other dental traits are outlined.

Black People↗
PubMed1980

The metaconule: a morphologic and familial analysis of a molar cusp in humans.

Incidence and size variability of the metaconule, an accessory maxillary molar cusp, is analyzed in a series of 1,217 living Melanesians. The range of morphologic variation is quantified on a six-grade ordinal scale developed to standardize observations. Total incidence of the metaconule decreases along a mesial-to-distal gradient, while mean size and size variability increase from M1 to M3. So, while the trait is less common on distal molars, it is on average larger. Estimation of the additive genetic component is 65% for the first molar but only 15% for the second. Trait incidence and heritability estimates are generally higher for females indicating the need for separate analysis by sex.

Female↗
PubMed1980

A study of occlusion and arch widths in families.

It is often claimed that occlusal variation ("malocclusion") is under strong genetic control. This study of a large age-standardized series of families (parents and offspring) shows that the genetic contribution to occlusal variation is quite low. On average, only about 10 percent of the variation in overjet, overbite, crowding, tooth rotations, and molar relationships results from nonenvironmental causes. In contrast, about 60 percent of the variation in measurements of arch size and shape is attributable to heredity.

Cephalometry↗
PubMedDate not supplied

Effect of the estrous cycle on susceptibility of female mice to intravaginal inoculation of herpes simplex virus type 2 (HSV-2).

In order to explore the effect of sexual maturity on the susceptibility of mice to genital herpesvirus infections, mice were separated into the four stages of the estrous cycle and inoculated intravaginally with varying doses of HSV-2, strain 186. Deaths were observed as indicators of susceptibility and were recorded as follows: proestrous, 33%; estrous, 16%; metestrous, 9% and diestrous, 75%. To determine the course of infection in animals inoculated at different stages of estrous, cotton swabs were used to collect vaginal specimens at various times post-virus inoculation for virus titration. All mice inoculated during diestrous were positive for virus as early as 6 hours post-virus inoculation and had titers that increased over a 3 day period. Mice inoculated in other stages of estrus were positive only briefly (at 6 h) or had no detectable virus. In order to verify the susceptibility associated with diestrous, mice were ovariectomized to produce a continuous diestrous (pseudodiestrous) and when inoculated greater than or equal to 66.7% died. In contrast, none of the mice which had been ovariectomized and treated with estrogen to simulate the estrus stage died. We postulate that in stages other than diestrous virus may adsorb to epithelial cells in the lumen of the vagina and/or be expelled from the body by nonspecific resistance functions, thus reducing the likelihood of vaginal infection.

Animals↗
PubMedDate not supplied

Predicting adult stature: a comparison of methodologies.

Three methods of predicting a child's adult height are in common use: Bayley and Pinneau (1952), Tanner et al. (1975) and Roche et al. (1975). The relative accuracies of these methods have been assessed using growth records (22 male, 24 female) from the Child Research Council, Denver, Colorado. A series of six ages from five years to mid-adolescence was examined. Testing all methods and ages within each sex with a multivariate design yielded significant differences in the methods' accuracies, but inspection of the data by age disclosed that the major discrimination occurred during adolescence, not childhood. Results also indicated that the method of skeletal age assessment (either Greulich--Pyle or TW2) is more critical to accurate height prediction than is the choice of prediction method per se. This is because of inter-population differences in the rate and pattern of progress towards maturity and thus indicates the need to compare the children under examination to the most appropriate population standards available.

Adolescent↗
PubMedDate not supplied

Normal length changes in hand bones during adulthood: exploratory study of ray two.

A longitudinal analysis was made of total length changes of the four epiphyseal bones of ray two, the index finger, during adulthood. Matched pairs of standardized hand-wrist radiographs on 37 individuals between earlier (means = 22 years) and later (means = 54 years) adult age-grades show that the distal and middle phalanges continue to increase in overall length; the proximal phalange exhibits no change; and the metacarpal significantly decreases in size. The changes in these normal adults are also discernible in cross-sectional data but are not obvious statistically. Causes of the specific increases and decreases remain speculative.

Adolescent↗
PubMedDate not supplied

Oral anomalies in the neonate, by race and gender, in an urban setting.

A broad range of developmental anomalies and morphologic variants may occur in the oral cavity of the newborn. Because many of these are transient (e.g.: palatal and alveolar cysts, lymphangioma), self-correcting with age, conventional assessments of older children can yield significantly altered trait incidences. A total of 500 normal full-term newborns (blacks and whites) were assessed by standardized criteria for 11 oral conditions, in addition to collating data on maternal conditions (age, gravidity, tobacco and alcohol use). Leukoedema and median alveolar notches were significantly more common in blacks, whereas palatal cysts were 2.5 times as likely to occur in whites. Ankyloglossia, three times as common in males, was the one trait to exhibit a significant predilection by gender. Low maternal age (less than 20 years) significantly enhanced the risk of alveolar lymphangioma in these data.

Female↗
PubMedDate not supplied

Effects of acidulated and neutral NaF solutions on bond strengths.

The application of topical fluoride after acid-etching substantially reduces the risk of enamel opacities and caries, but fluoride treatment can reduce strength of the enamel-adhesive interface to a measurable extent. In this in vitro study there was a slight reduction (statistically inconsequential) in bond strength with the use of 2.0% aqueous NaF. In contrast, two acidulated solutions tested here both showed marked reductions (ca. 25%) in bond strengths.

Dental Bonding↗
PubMedDate not supplied

Delayed tooth formation in low birthweight African-American children.

Low birthweight (LBW) infants are susceptible to several developmental problems (e.g., pulmonary diseases, hyperbilirubinemia, hypocalcemia) with potentially long-lasting effects that slow growth during infancy and childhood. Dental age (DA), judged from stages of permanent tooth mineralization, was scored in 4- to 7-year-old LBW African-American children (N = 66; x = 5.5 years) to test whether they were delayed due to LBW and its consequences. Data were matched in a case-control fashion to African-American children with normal birth-weights (N = 76). Only the early-forming teeth (incisors, first molars) were delayed significantly in their formation. Children with the lowest height-for-age centiles were the most delayed dentally which suggests that height status would improve as dental age caught up with chronological age (CA). Older children were more delayed because there is a proportionately greater opportunity for DA to diverge from CA as children grow older. Since only those teeth undergoing rapid differentiation neonatally were affected systematically, it was speculated that perinatal insults may have an enduring impact on developing primordia, while leaving later-forming teeth unaffected.

Age Factors↗