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Biomedical subjects

C E Boklage

Publications and source records attributed to C E Boklage.

At least 19 recordsLinked to original sources
PubMed1996

Effects of a behavioural rhythm on conception probability and pregnancy outcome.

This paper concerns a behaviour-driven weekday rhythm in conception rates in a large natural human population. From 1978 to 1991, North Carolina normal live single births arose from menstrual cycles which began on Monday in clear excess over other weekdays. Cycles beginning on Friday were also in excess. Cycles starting on Saturday and Sunday, or Wednesday and Thursday, each represented significantly less than one in seven of weekly totals. The source of the observed synchrony was a Sunday morning peak of coital frequency. Average cycles which began on Monday had their most fertile day on the most likely day for intercourse, translating a weekly insemination rhythm into a weekly conception rate rhythm. The secondary conception peak in Friday-onset cycles increased with age, to become the major peak for mothers aged > 30 years. We interpret this to represent a previously unreported second type of cycle with a modal follicular phase length of 10 days, the frequency of which increases with age. Several large groups of anomalous human births depart significantly from the weekday rhythm of normal conceptions. These outcomes parallel results of experimental interference with fertilization timing in estruative mammals. We believe that this implicates anomalous fertilization timing in several of the most numerous anomalies of human prenatal development.

Behavior↗
PubMed1992

Annual and sub-annual rhythms in human conception rates: time-series analyses show annual and weekday but no monthly rhythms in daily counts for last normal menses.

Methods of time-series analysis, which are widely used to good effect in physical sciences and econometrics, have found little use in much-needed analyses of cyclical biological phenomena. Here we apply those methods to analyses of rhythmic patterns in human conception rates. Our results confirm the annual periodicity of monthly counts of total viable conceptions, demonstrate a weekday rhythm reflecting interaction of conjugal coital rhythms with individual menstrual fertility cycles, and find no evidence of any other significant repeating pattern.

Artifacts↗
PubMed1987

Twinning, nonrighthandedness, and fusion malformations: evidence for heritable causal elements held in common.

Certain relatively common congenital malformations that are reported to be excessive in frequency among twins are also found in excess among first-degree relatives of twins. They are familially associated with each other. Like twinning, they are familially associated with nonrighthandedness (NRH). They also share the fact that they affect structures that are built by the fusion of bilateral embryonic halves and then remodeled under the influence of neural crest mesenchyme. This conjunction of associations suggests that twinning, NRH, and the fusion malformations share causal elements, some of which may be heritable. Determination of spatial relationships in embryogenesis ("embryonic body symmetry determination") and the functions of neural crest mesenchyme may be mechanisms unifying these effects.

Diseases in Twins↗
PubMed1987

Developmental differences between singletons and twins in distributions of dental diameter asymmetries.

Craniofacial development and behavioral development differs between human twins and singletons in several ways which are related to symmetry development and detectable in adults. In most of those ways, twin zygosity groups do not differ. Here we use distributions of dental diameters, as a model subsystem of craniofacial development, to show that twins, of both zygosities and both sexes, are substantially more symmetrical than singletons. The observed differences are consistent with previous related observations, none of which can readily be explained by any consequence of twin gestation. They seem instead to represent peculiarities of developmental biology familially associated with twinning.

Adolescent↗
PubMed1987

Race, zygosity, and mortality among twins: interaction of myth and method.

For epidemiological purposes, it is customary to assume that same-sex (SS) dizygotic (DZ) twin pairs are approximately equal in number to unlike-sex (OS)-DZs, the remainder of the SS pairs being monozygotic (MZ). It is also customary to consider OS-DZs to be epidemiologically representative of all DZs, which can only mean that difference in frequency of any trait between OS and SS twins is due to the MZ fraction of the SS twins. Since this is assumed as a premise, there is little value in its usual appearance as the result. The basic tenet of twin biology, that most twin excess anomalies are due to MZs, is a myth self-perpetuated by a methodological tautology, and is false, at least for mortality. In a consecutively ascertained and prospectively studied sample of 616 twin pairs, over 80% diagnosed for zygosity, it can be shown that the standard assumption mentioned above have given impossible answers. The most probable possible answer is that mortality does not differ greatly with zygosity overall, but that SSDZ mortality is much higher than that of OS twins, and probably even higher than that of MZs. Race differences in the probable answers further suggest that standard assumptions of the Weinberg method may have consistently provided false explanations for race differences in the OS fraction of twin pairs.

Chorion↗
PubMed1987

The organization of the oocyte and embryogenesis in twinning and fusion malformations.

Certain congenital malformations occur in excess among twins and also among first-degree relatives of twins. In the general population, these anomalies are familially associated with each other, and, like twinning, familially associated with unusual brain function asymmetry. They affect structures built by fusion of bilateral embryonic halves and remodeled under major influence of neural crest mesenchyme. This conjunction of associations suggests that twinning, symmetry development, and this group of malformations might share causal elements at least some of which are heritable. The problem here is the absence of zygosity differences in these relationships, because of which they cannot be explained within the biology of twinning as it has been understood. A potential resolution is offered by way of a mechanism common to MZ and DZ twinning, involving a relationship between oocyte organization and the determination of body symmetries.

Congenital Abnormalities↗
PubMed1985

Interactions between opposite-sex dizygotic fetuses and the assumptions of Weinberg difference method epidemiology.

The Weinberg difference method in twin epidemiology may be subject to a major error related to a fundamental assumption that seems not to have been previously questioned. Results presented here indicate that the mortality of like-sex dizygotics (DZs) resembles that of monozygotics (MZs) much more than that of unlike-sex DZs, who are not representative of any other group. Unlike-sex twins enjoy a relative protection from fetal and neonatal mortality and probably from at least one effect of the transient perinatal hypoxia common for second twins. Unlike-sex twins develop, and maintain into adulthood, an intermediate gender phenotype with respect to integration of craniofacial growth.

Birth Order↗
PubMed1984

Differences in protocols of craniofacial development related to twinship and zygosity.

Using 56 adult dental diameters as a subsystem model for craniofacial development, we show that monozygotic (MZ), dizygotic (DZ), and singleton groups differ significantly in developmental relationships assessed by multivariate statistical methods under commonly accepted assumptions. Given the differences observed, we suggest that any assumption of developmental equivalence between MZ and DZ twins, or between twins of either group and singletons, for variables of craniofacial or behavioral development, may be subject to serious doubt. Implications for twin study theory and methodology, and for study of early human development, are discussed.

Birth Order↗
PubMed1981

On the distribution of nonrighthandedness among twins and their families.

In 773 three-generation families of twins, individual probability of nonrighthandedness (NRH) depends significantly on the handedness of that individual's parents. The parents of twins are much more often NRH than are their nontwinbearing siblings. The twins and their siblings apparently inherit the excess liability for NRH shown by their parents. Monozygotic (MZ) pairs are significantly about twice as often concordant (casewise) for handedness as dizygotic (DZ) pairs. Overall, the best-fitting mode of transmission is autosomal, NRH dominant to RH with penetrance of about 50% in the heterozygote, or multifactorial, with heritability of 60-70%. Under the major-gene approach, heterogeneity seems likely, with about one-third of the families showing no NRH outside of the twin sibships. MZ/DZ concordance ratio is about four in those families, suggestive of recessive inheritance. A 1.16-fold excess of NRH in twins compared to their siblings, and a 1.8-fold excess in the second-born members of same-sex discordant paris, leaves open the possibility that a minor portion of NRH in twins may be secondary to transient hypoxia and/or acidosis.

Adolescent↗
PubMed1977

Schizophrenia, brain asymmetry development, and twinning: cellular relationship with etiological and possibly prognostic implications.

Discordance for schizophrenia in monozygotic twins has been interpreted as evidence of the role of environment in the etiology fo schizophrenia, with "environment" usually, in practical parlance, carrying Freudian and Sinnerian connotations. MZ twins are often discordant for certain brain development deviations (i) to which they are specially prone, (ii) which show other evidence of having genetic etiologies, and (iii) which involve embryonic symmetry development. MZ twinning is an embryonic symmetry anomaly; its association with others is not surprising. Neurophysiological manifestations of schizoprenia are markedly asymmetric, as is much of normal human mental function. Unusual brain function asymmetry is herein shown to be a factor in virtually every appropriately tested case of MZ discordant schizophrenia.

Brain↗
PubMed1973

The lambda F mutants belong to two cistrons.

Amber mutants previously mapped at seven sites in head gene F exhibit two contrasting phenotypes. Mutant F423, located in the right half of gene F, makes defective head particles with normal size lambdaDNA. These particles are complemented by crude lysates of mutants in other head genes. Mutants F785, F471 and F730 map in three adjacent sites in the left half of gene F. They are not complemented by lysates of other head mutants and do not produce headlike particles. Their lysates complement the incomplete heads present in F423. In vivo all three mutants are complemented by F423 but not by each other.

Centrifugation, Density Gradient↗