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Biomedical subjects

B C Campbell

Publications and source records attributed to B C Campbell.

At least 37 records · Page 2Linked to original sources
PubMed1995

Bacterial entomopathogens from the Drosophila paulistorum semispecies complex.

Bacteria which are infectious by inoculation in lepidoptera have been isolated and characterized from semispecies comprising the Drosophila paulistorum complex. These microorganisms are pathogenic toward lepidopteran hosts such as Heliothis virescens when introduced by injection of Drosophila tissue extracts and have been given the trivial name DpLE (D. paulistorum lepidopteran entomopathogen). The DpLE from two of the semispecies, Transitional and Andean, were determined to be related to Proteus vulgaris based upon nucleotide sequence comparisons of 16S rDNA genes. Infectivity and 16S rDNA-based PCR assays showed the bacterium to be localized in a number of drosophilid tissues except adult heads and thoraces. Based upon similar experiments, the DpLE in transinfected Heliothis larvae were found in all tissues assayed prior to the onset of mortality. Stocks of Drosophila which had spontaneously lost DpLE continued to produce sterile sons when crossed with incompatible semispecies' females, confirming that the bacilliform DpLE is not the causative agent of the Drosophila paulistorum intersemispecific hybrid male sterility. Acquisition of the sequences of the 16S rDNA molecules of DpLE from all six semispecies permitted the construction of a phylogenetic tree in which the groupings were found not to be congruent with the phylogenies of their insect hosts.

Animals↗
PubMed1995

Stress and age at menarche of mothers and daughters.

The hypothesis that psychological stress during early childhood leads to advanced reproductive maturation was assessed using data from the California Childhood Health and Development Study. Regression analyses failed to indicate that bed wetting, nightmares or thumb-sucking at age 5 predict age at menarche, regardless of controls for mother's age at menarche. Among socioeconomic variables suggested as contextual stressors measured at age 9-11 only mother's education was a significant predictor of daughter's age at menarche, though its effect is trivial compared to mother's age at menarche. Path analysis on a subsample of the subjects failed to demonstrate the hypothesised indirect effect of mother's age at menarche on daughter's age at menarche acting through early marriage and marital dissolution. These results cast doubt on the theory that early childhood stress is the key to divergent reproductive strategies among females based on the timing of reproductive maturation.

California↗
PubMed1995

Reliability of salivary testosterone measurements: a multicenter evaluation.

The reliability of salivary testosterone assays was evaluated by nine laboratories in four countries. Each laboratory used its own RIA procedures to assay samples from a set of 100 male and 100 female subjects. Agreement among the laboratories on mean scores was within the range reported by Read (Ann N Y Acad Sci 1993; 694: 161-76). Overall agreement on individual scores, as indicated by the intraclass correlation coefficient computed within subjects across laboratories, was r = 0.87 for men and r = 0.78 for women. Mean agreement between each laboratory and the combined set of all other laboratories (via Fisher's Z-transformation) was r = 0.61 for men and r = 0.58 for women. We take these latter values to be the best estimates of the average reliability of laboratories in their ordering of individual samples.

Female↗
PubMed1994

Implications of hormonal influences on sexual behavior for demographic models of reproduction.

In exploring the implications of hormonal influences on sexual behavior for reproduction, we have focused on androgens because of the convincing evidence for androgenic effects on female sexual motivation. We have been guided by the simple idea, based on clinical findings among hyperandrogenic women, that higher testosterone levels will increase female sexual motivation which in turn will result in increased coital frequency. However, careful consideration of the evidence fails to confirm such a role for testosterone in sexual behavior among normal women at any point in the reproductive span. While some amount of testosterone appears to be important in maintaining female sexual motivation, there is little evidence that variation in testosterone within the normal range is associated with variation in sexual motivation. Reported associations between testosterone and sexual behavior among married women cannot be interpreted as resulting from androgenic effects on sexual motivation. Thus we are left with the task of explaining why testosterone does not appear to play the same role in libido among hyperandrogenic and normal women. As mentioned earlier, some of the difference may attributable to the much higher levels of testosterone among hyperandrogenic women. Sherwin points out that the levels of sexual motivation decline with declining testosterone levels even while testosterone is well above normally occurring levels. It is possible that the brain is simply not sensitive to the variation in testosterone levels found in normal women. Other evidence suggests that the presence of intact ovaries may be equally important. A recent study of androgen replacement in naturally post-menopausal women failed to find a dramatic effect of testosterone on sexual motivation and behavior, despite levels similar to those in studies on surgically menopausal women, pointing to the importance of other factors associated with the presence of ovaries. A similar point can be made with regard to hyperandrogenism related to endogenous sources of testosterone, as in the case of PCOS. High levels of testosterone effectively disrupt ovarian function and interfere with other ovarian processes. Among hyperandrogenic women sexual behavior appears to be related to the direct effects of androgens on motivation, while the indirect effects of estrogen and progesterone are essentially eliminated. Among normal women, on the other hand, there is little evidence for such a dominating role of a direct androgenic effect on sexual behavior. Instead, other ovarian hormones, including estrogen and progesterone may also play a demonstrable role, despite the lack of strong evidence at this point.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1994

Host factors that influence the duration of menstrual bleeding.

We assessed the association between weight, exercise, and stress and the duration of menstrual bleeding in a 1-year prospective menstrual diary study of 166 college first-year women, age 17-19 years. Low weight-for-height increased expected bleed duration by 0.39 day. Dieting to lose weight reduced bleed length by 0.43 day. Women who did no moderate or hard exercise bled about a quarter of a day longer than women at the median level of physical activity.

Adolescent↗
PubMed1994

Evolutionary origin of whiteflies (Hemiptera: Sternorrhyncha: Aleyrodidae) inferred from 18S rDNA sequences.

Phylogenetic analysis of 18S rDNA nucleotide sequences of hemipteran exemplars shows Sternorrhyncha (psyllids, whiteflies, aphids and scales) is monophyletic and forms a sister group to all other hemipterans (Euhemiptera). Whiteflies form a sister group to all other Sternorrhyncha. Primary structures of 18S rDNAs of all sternorrhynchans are exceptionally long (approximately 2200 to approximately 2500 bp) due to internal expansions. These expansions are a synapomorphy of Sternorrhyncha; other hemipterans possess shorter 18S rDNAs (approximately 1900 to approximately 1925 bp). The 18S rDNA of whiteflies is the longest recorded to date and has a base substitution rate of approximately 3 times greater than Euhemiptera taxa examined. The relevance of these findings to the fossil record, feeding strategies, reproductive biologies, and geoclimatic distribution is discussed.

Amino Acid Sequence↗
PubMed1993

Dermatoglyphic asymmetry and testosterone levels in normal males.

Dermatoglyphic prints and salivary samples were taken on a sample of 39 adult males. A statistical relationship between dermatoglyphic asymmetry and adult testosterone levels as measured in saliva was examined for seven dermatoglyphic variables by means of correlation, regression, and analysis of covariance, controlling for age and stature when necessary. The first two types of analyses indicated a significant effect of testosterone level upon the asymmetry of three dermatoglyphic variables: a-b ridge count, palmar pattern intensity, and the combined pattern intensity of palm and digits. Analysis of covariance, which examined the effect of testosterone level as a categorical variable, while holding age or stature constant, demonstrated the asymmetry of five variables to be significantly affected by testosterone level: radial digital count, digital pattern intensity, palmar pattern intensity, total digital ridge count, and the combined palmar and digital intensity. Although there is as yet only associational evidence linking levels of prenatal and secondary testosterone, the results of the present study lend support to the hypothesis that prenatal testosterone levels may have a significant effect on the development of dermatoglyphics.

Adult↗
PubMed1993

Phylogenetic affiliation of BEV, a bacterial parasite of the leafhopper Euscelidius variegatus, on the basis of 16S rDNA sequences.

The phylogenetic relationship of a nonflagellated, Gram-negative, rod-shaped intracellular bacterial parasite (BEV) of the leafhopper Euscelidius variegatus to other bacteria within the class Proteobacteria was determined by sequence analysis of 16S rDNAs. The presence of specific signature nucleotides showed this bacterium to be a member of the gamma-3 subdivision of the Proteobacteria. Phylogenetic analysis based on maximum parsimony placed BEV within a clade in the Enterobacteriaceae, which includes a number of bacteria that are facultative symbiotes of insects and have a common ancestor with Proteus vulgaris. Within this clade, BEV is most closely related to a bacterium identified as the secondary endosymbiote of another homopteran, the pea aphid, Acyrthosiphon pisum.

Animals↗
PubMed1993

Congruent evolution between whiteflies (Homoptera: Aleyrodidae) and their bacterial endosymbionts based on respective 18S and 16S rDNAs.

Whiteflies (family Aleyrodidae) possess heritable eubacterial endosymbionts sustained in specialized organ-like structure called mycetomes. Comparisons of distances between the ash whitefly, Siphoninus phillyreae, and two biotypes ("A" and "B") of the sweetpotato whitefly, Bemisia tabaci, based on sequence analysis of genes for 18S rRNAs (rDNAs), were equivalent to the distances represented by the 16S rDNAs of their respective endosymbionts. This finding indicates that evolutionary divergence in whitefly hosts and their endosymbionts is congruent. The nucleotide sequences of the 18S rDNAs and endosymbiont 16S rDNAs indicate the two biotypes of B. tabaci are the same species.

Animals↗
PubMed1993

Phylogeny of the Nasonia species complex (Hymenoptera: Pteromalidae) inferred from an internal transcribed spacer (ITS2) and 28S rDNA sequences.

The phylogeny of the cryptic species complex of wasps in the genus Nasonia was inferred by analysis of nucleotide sequences of an rDNA internal transcribed spacer (ITS2) and the D2 region of 28S rDNA. Phylogenetic analysis showed that N. vitripennis descended from a theoretical common ancestor with that of a lineage that diverged into N. longicornis and N. giraulti. Differences in the ITS2 regions clearly distinguished two strains of N. giraulti. Another member of the Dibrachys Group, Trichomalopsis dubius, was placed outside of the Nasonia complex. The D2 region had a base substitution rate approximately 2 times slower than the ITS2 region and was used to resolve the phylogenetic affiliation of an eulophid, Melittobia digitata, to the pteromalids. Tree topology of the Nasonia complex was congruent with the phylogeny of a cluster of Wolbachia bacteria which infect these insects. The possible role of these bacteria in driving speciation is discussed.

Animals↗
PubMed1992

Menstrual variation in salivary testosterone among regularly cycling women.

To determine menstrual variation in salivary testosterone daily saliva samples were collected from 20 regularly cycling women. Results indicate that the menstrual profile of salivary testosterone for both ovulatory and anovulatory cycles exhibits local peaks during the follicular phase and at midcycle, as well as a luteal trough. However, the testosterone profile for anovulatory cycles exhibited a later midcycle peak than that for ovulatory cycles, as well as significantly higher average testosterone levels. These results extend the observation of a midcycle peak in serum testosterone to saliva and suggest the existence of a follicular peak in unbound testosterone coincident with the early androgen production of a cohort of developing follicles.

Adult↗
PubMed1991

Evidence for the establishment of aphid-eubacterium endosymbiosis in an ancestor of four aphid families.

Aphids (superfamily Aphidoidea) contain eubacterial endosymbionts localized within specialized cells (mycetocytes). The endosymbionts are essential for the survival of the aphid hosts. Sequence analyses of the 16S rRNAs from endosymbionts of 11 aphid species from seven tribes and four families have indicated that the endosymbionts are monophyletic. Furthermore, phylogenetic relationships within the symbiont clade parallel the relationships of the corresponding aphid hosts. Our findings suggest that this endocytobiotic association was established in a common ancestor of the four aphid families with subsequent diversification into the present species of aphids and their endosymbionts.

Animals↗
PubMed1986

Intracoronary thrombolytic therapy performed within a coronary care unit: one year's experience.

Acute myocardial infarction is associated with a high incidence of occluding coronary arterial thrombi. Thrombolytic therapy has been advocated to restore coronary artery blood flow and to reduce myocardial damage. Coronary arteriography and intracoronary thrombolytic therapy was administered to 61 patients admitted to a Coronary Care Unit within eight hours of symptoms. Successful reperfusion was obtained in 38 of 46 single vessel occlusions associated with a first coronary attack. Failure of reperfusion occurred in patients with two vessel occlusions or with cardiogenic shock. This study demonstrates the feasibility of applying this technique within a Coronary Care Unit with low capital and running costs, and suggests that its widespread application is possible even within the setting of a District General Hospital.

Coronary Angiography↗