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PubMed2005

Effect of a preparation containing a fucose-rich polysaccharide on periorbital wrinkles of human voluntaries.

BACKGROUND: Skin aging is accompanied by wrinkle formation. At some sites, as the periorbital skin, this is a relatively early phenomenon, variable from one woman to the other and even between the right and left eye. PURPOSE: We tested the effect of a preparation with fucose-rich oligo- and polysaccharide (FROP-3) on periorbital wrinkles (crow's feet) on a team of voluntaries. METHOD: The efficiency of a preparation containing as active principle a fucose-rich polysaccharide in a base-cream for the treatment of temporal periorbital wrinkles on 20 voluntary women was tested as follows: the women applied the cream twice a day for 4 weeks. Negative replicas were taken on the periorbital skin before and after 4 weeks of application of the cream. The results were evaluated by semi-automated morphometry on the plastic replicas and expressed as the 'wrinkle-factor' obtained by multiplying total wrinkle length in millimeters by the average wrinkle width. RESULTS: After 4 weeks of treatment, there was a significant improvement of the periorbital wrinkles for the majority of the voluntary team who tested the cream. On the 29 periocular wrinkles examined 65% showed an improvement at the end of the treatment. In two cases, the improvement was 100% on one eye (disappearance of the crow's feet) and of 75% and 79% on the other eye. On six eyes, there was no significant change after the end of the treatment, and on four eyes a worsening was observed. The age-dependent modifications showed that improvement was independent of age and was the result of individual skin reactions to the cream. The occurrence and the severity of crow's feet is highly individual, and differs from one side of the face to the other for the same person. These strong individual variations explain the highly variable results, not only from one woman to the other but also comparing one side of the face to the other for the same person. CONCLUSION: Under the effect of 4 weeks of treatment with the FROP-3-containing cream, most of the voluntaries had their periorbital wrinkles attenuated and some women showed a total regression of crow's feet on one of their eyes.

Adult↗
PubMed1977

Treatment of captive giant Canada geese affected by avian cholera.

In the spring of 1975, an epornitic of avian cholera in Nebraska affected wild waterfowl, common crows (Corvus brachyrhynchos), and a captive flock of guant Canada geese (Branta canadensis maxima). Measures taken to control the disease in the captive geese included flushing the water of their pen with fresh well water, parenteral (50mg oxytetracycline intramuscularly) and feed (tetracycline 500 g/ton) antibiotic treatment, and removing dead waterfowl and crows from the pen, and keeping wild waterfowl and crows out of the pen. Other measures taken to prevent a recurrence of the outbreak included monitoring the area with susceptible sentinel birds and culturing nasal swabs for Pasteurella multocida. Young Canada geese and wood ducks (Aix sponsa) raised in the area also were cultured before release to assure that carriers would not be released into the wild. Presently, ponds in the pen have been dried up so that the area is less attractive to wild waterfowl. Swine feeders and waterers that have been modified to discourage their use by crows are being used to feed and water the geese.

Animals↗
PubMed2003

Bayesian analysis of a previously published genome screen for panic disorder reveals new and compelling evidence for linkage to chromosome 7.

This article presents a Bayesian re-analysis of a linkage study of panic disorder Crowe et al. [2001: Am J Med Genet (Neuropsychiatr Genet) 105:105-109]. In the initial analysis Crowe et al. failed to find compelling evidence for linkage based on either LOD scores or NPL scores anywhere in the genome. The maximum LOD score was 2.23 on chromosome 7 at marker D7S2846 (57.79 cM according to Marshfield). Over the past several years we have been developing a Bayesian alternative approach to linkage analysis, based on direct measurement of the posterior probability of linkage (PPL), and have shown elsewhere that this approach has several advantages over the available alternatives for mapping complex-disease genes Vieland [1998: Am J Med Genet 63:947-954]; Wang et al. [1999: Genet Epidemiol 17(Suppl 1):S749-S754]; Wang et al. [2000: Ann Hum Genet 64:533-553]; and Vieland et al. [2001: Hum Hered 51:199-208]. One limitation of this approach in previous applications has been that it required the investigator to specify a fixed genetic model for the trait. We employ a new implementation of the PPL that treats the unknown trait model as a vector of nuisance parameters, which is integrated out of the PPL equation. When we apply this new model-integrated version of the PPL to the data of Crowe et al. [2001: Am J Med Genet (Neuropsychiatr Genet) 105:105-109] we obtain much clearer evidence than previously reported for a locus on chromosome 7, with an 80% probability of linkage to marker D7S521. A second location is also identified on chromosome 16 near marker D16S749 (PPL = 24%). The results for the remainder of the genome are consistently low. The two loci identified here are also supported by independent evidence from other studies.

Bayes Theorem↗
PubMed2006

Effect of stimulus orderability and reinforcement history on transitive responding in pigeons.

Transitive responding in humans and non-human animals has attracted considerable attention because of its presumably inferential nature. In an attempt to replicate our earlier study with crows [Lazareva, O.F., Smirnova, A.A., Bagozkaja, M.S., Zorina, Z.A., Rayevsky, V.V., Wasserman, E.A., 2004. Transitive responding in hooded crows requires linearly ordered stimuli. J. Exp. Anal. Behav. 82, 1-19], we trained pigeons to discriminate overlapping pairs of colored squares (A+ B-, B+ C-, C+ D-, and D+ E-). For some birds, the colored squares, or primary stimuli, were followed by a circle of the same color (feedback stimuli) whose diameter decreased from A to E (Ordered Feedback group); these circles were made available to help order the stimuli along a physical dimension. For other birds, all of the feedback stimuli had the same diameter (Constant Feedback group). In later testing, novel choice pairs were presented, including the critical BD pair. The pigeons' reinforcement history with Stimuli B and D was controlled, so that the birds should not have chosen Stimulus B during the BD test. Unlike the crows, the pigeons selected Stimulus B over Stimulus D in both ordered and Constant Feedback groups, suggesting that the orderability of the post-choice feedback stimuli did not affect pigeons' transitive responding. Post hoc simulations showed that associative models [Wynne, C.D.L., 1995. Reinforcement accounts for transitive inference (TI) performance. Anim. Learn. Behav. 23, 207-217; Siemann, M., Delius, J.D., 1998. Algebraic learning and neural network models for transitive and non-transitive responding. Eur. J. Cogn. Psychol. 10, 307-334] failed to predict pigeons' responding in the BD test.

Animals↗
PubMed1999

Commentary on Annett, Yeo et al., Klar, Saugstad and Orr: cerebral asymmetry, language and psychosis--the case for a Homo sapiens-specific sex-linked gene for brain growth.

Annett, Yeo et al. and Klar have each proposed theories that relate the genetics of cerebral lateralization to predisposition to psychosis. These theories are considered in relation to the central paradox that psychosis is associated with a substantial biological disadvantage. Annett's heterozygote advantage hypothesis critically identified lateralization as a major determinant of ability, but it appears that what is inherited is degrees (as suggested by Yeo et al.) rather than (or as well as) direction of lateralization. Relative hand skill has been shown (Crow, T.J., Crow, L.R., Done, D.J., Leask, S.J., 1998. Relative hand skill predicts academic ability: global deficits at the point of hemispheric indecision. Neuropsychologia 36, 1275-1282.) to be a powerful predictor (interacting with sex) of academic ability but the greatest region of vulnerability (that includes reading disability and predisposition to psychosis) is close to the point of equal hand skill ('hemispheric indecision'). In contrast with Annett's single locus, Yeo's polygenic and Klar's strand-segregation hypotheses, each of which postulates an autosomal locus or loci, the hypothesis of a single gene for asymmetry located in a sex-specific region of homology on both X and Y chromosomes can account for sex differences, as observed in age of onset, and premorbid precursors of psychosis, as well as differences in the general population in relation to degrees of hand skill, verbal ability and cerebral asymmetry. The evolutionarily recent transposition to, and subsequent paracentric inversion in, the Y chromosome short arm of a 4-Mb block from Xq21.3 (the proximal long arm of the X) are candidates for speciation events in the lineage that led to Homo sapiens. A gene associated with a range of variation (that may be due to a high mutation site, or perhaps to epigenetic modification) on the Y that overlaps with, but differs quantitatively from, that on the X may explain the sex differences associated with psychosis, and may be relevant to its persistence. Such a gene could be the principal determinant in Man of the rate of brain growth, as suggested by Saugstad and by the findings of a recent study of adolescent onset psychosis (James, A., Crow, T.J., Renowden, S., Wardell, M., Smith, D.M., Anslow, P., in press. Is the course of brain development in schizophrenia delayed? Evidence from onsets in adolescence. Schizophr. Res.).

Biological Evolution↗
PubMed2006

Role of corvids in epidemiology of west Nile virus in southern California.

The invasion of different southern California landscapes by West Nile virus (WNV) and its subsequent amplification to epidemic levels during 2004 enabled us to study the impact of differing corvid populations in three biomes: the hot Colorado desert with few corvids (Coachella Valley), the southern San Joaquin Valley (Kern County) with large western scrub-jay but small American crow populations, and the cool maritime coast (Los Angeles) with a large clustered American crow population. Similar surveillance programs in all three areas monitored infection rates in mosquitoes, seroconversion rates in sentinel chickens, seroprevalence in wild birds, numbers of dead birds reported by the public, and the occurrence of human cases. Infection rates in Culex tarsalis Coquillett and sentinel chicken seroconversion rates were statistically similar among all three areas, indicating that highly competent mosquito hosts were capable of maintaining enzootic WNV transmission among less competent and widely distributed avian hosts, most likely house sparrows and house finches. In contrast, infection rates in Culex pipiens quinquefasciatus Say were statistically higher in Kern and Los Angeles counties with elevated corvid populations than in Coachella Valley with few corvids. Spatial analyses of dead corvids showed significant clusters near known American crow roosts in Los Angeles that were congruent with clusters of human cases. In this area, the incidence of human and Cx. p. quinquefasciatus infection was significantly greater within corvid clusters than without, indicating their importance in virus amplification and as a risk factor for human infection. In contrast the uniform dispersion by territorial western scrub-jays resulted in a high, but evenly distributed, incidence of human disease in Kern County.

Animals↗
PubMedDate not supplied

Effect of botulinum toxin pretreatment on laser resurfacing results: a prospective, randomized, blinded trial.

BACKGROUND: Facial laser resurfacing and chemodenervation with botulinum toxin type A are used independently as means of nonsurgical facial rejuvenation. Recent reports in the literature have described combining these 2 therapies, claiming improved and longer-lasting laser resurfacing results. To date, no scientific investigation has been undertaken to prove or disprove this theory. DESIGN: Institutional review board-approved, prospective, randomized, blinded study at university-affiliated outpatient cosmetic surgery offices. INTERVENTION: Patients had one side of their face injected, at specific anatomic subsites (crow's feet, horizontal forehead furrows, and glabellar frown lines), with botulinum toxin 1 week before laser resurfacing. After receiving an injection, patients underwent cutaneous laser exfoliation on both sides of the face with either a carbon dioxide or an erbium dual-mode laser. MAIN OUTCOME MEASURES: Patients' injected (experimental) and noninjected (control) sides were compared after laser resurfacing. Follow-up was documented at 6 weeks, 3 months, and 6 months after laser resurfacing. Subjective evaluation, based on a visual analog scale, was performed in person by a blinded observer. Furthermore, a blinded panel of 3 expert judges (1 facial plastic surgeon, 1 oculoplastic surgeon, and 1 cosmetic dermatologist) graded 35-mm photographs taken during postoperative follow-up visits. RESULTS: Ten female patients were enrolled in the study. A 2-tailed t test showed that all sites that were pretreated with botulinum toxin showed statistically significant improvement (P< or =.05) over the nontreated side, with the crow's feet region showing the greatest improvement. Comparing results between the carbon dioxide and erbium lasers did not result in any statistically significant differences. CONCLUSIONS: Hyperdynamic facial lines, pretreated with botulinum toxin before laser resurfacing, heal in a smoother rhytid-diminished fashion. These results were clinically most significant in the crow's feet region. We recommend pretreatment of movement-associated rhytides with botulinum toxin before laser resurfacing. For optimum results, we further recommend continued maintenance therapy with botulinum toxin postoperatively.

Adult↗
PubMed1997

The management of hyperfunctional facial lines with botulinum toxin. A collaborative study of 210 injection sites in 162 patients.

OBJECTIVE: To determine the optimum dose and efficacy of botulinum toxin injections in the management of hyperfunctional facial lines. DESIGN: This study included 210 hyperfunctional facial sites in 162 different patients. The patients had preinjection and postinjection photographic documentation and ratings on a 4-point qualitative evaluation scale of lines at rest and with action. The patients then had botulinum toxin type A injections via a monopolar hollow bore, Teflon-coated electromyographic needle into the facial muscles associated with the hyperfunctional lines. The total dose for each region of 1.25 to 25 U was divided into 1.25- to 5-U aliquots representing 0.1 to 0.2 mL per injection site, depending on the site and the prior experience with that patient on using toxin. The patients had their reevaluation at 2 to 3 weeks after injection. Patients returned for further follow-up when the therapeutic effect diminished. PATIENTS: One hundred sixty-two patients had 210 hyperfunctional sites evaluated and injected. The group consisted of 25 male patients and 137 female patients ranging in age from 21 to 78 years with a mean (+/-SD) of 46.1 (+/-1.98) years. All patients had cosmetically troubling hyperfunctional lines involving the forehead, glabella, crow's feet (lateral canthal lines), nasolabial area, platysma, and mentalis region. RESULTS: All patients had an effect of toxin within the first 24 to 72 hours. Ninety-five percent of the patients treated had cosmetic improvement of unsightly facial lines or contractions. The best results were achieved in management of the forehead lines, followed by glabella, crow's feet, and nasolabial. The dose for forehead lines was 5 to 25 U (mean +/- SD, 17.3 +/- 6.2 U); glabellar lines, 5 to 20 U (mean +/- SD, 11.1 +/- 3.1 U); crow's feet, 5 to 15 U (mean +/- SD, 6.2 +/- 1.6 U); nasolabial, 2.5 to 5 U (mean +/- SD, 3.12 +/- 1.2 U); and platysma, 10 to 20 (mean +/- SD, 15 +/- 4.0 U). Evaluation by age and site suggested a trend of increased toxin dose with increased age. Effects of the toxin are usually seen 24 to 72 hours after injection, and last from 3 to 6 months, whereon the increased muscular activity returns, as do the hyperfunctional lines. The only morbidity was related to temporary mild weakness of other adjacent facial muscles. There were no systemic side effects noted. CONCLUSION: Botulinum toxin is a safe and important adjunctive technique for the management of patients with symptomatic hyperfunctional facial lines.

Adult↗
PubMed2002

Accuracy of retrospective reports of infections during pregnancy.

A large body of research suggests a relationship between maternal influenza and the development of schizophrenia in the adult offspring. Some researchers, however, have questioned this association. A study by Crow and Done (1992) asserts that prenatal exposure to influenza does not cause schizophrenia. The methodology employed by Crow and Done may account for their null findings. Crow and colleagues assessed influenza by asking mothers at the time of birth to recall influenza infections experienced during pregnancy. Such retrospective recall may bias reporting. We assessed influenza symptoms during pregnancy in a group of 136 mothers at the twenty-fifth week of pregnancy, and again one or two days after birth. We compared accounts of influenza at the twenty-fifth week to recollection of influenza after birth. Results suggest that mothers tend to under-report infections when recalling infections after birth. Retrospective assessment of influenza symptoms at birth may be an inaccurate method of assessing influenza during pregnancy.

Female↗
PubMed1988

Influence of age and splanchnic nerve on the action of melatonin in the adrenomedullary catecholamine content and blood glucose level in the avian group.

A single intraperitoneal (IP) melatonin injection (0.5 mg/100 g body wt.) caused an increase in norepinephrine (NE) fluorescence and elevation of NE content in newly-hatched pigeons (Columba livia), but a reduction of NE fluorescence and depletion of NE content in the adrenal medulla of newly-hatched crows (Corvus splendens) after 0.5 h of treatment. In contrast, in adults melatonin caused increase in NE fluorescence and elevation of NE content only in the parakeet (Psittacula krameri). Half an hour of IP melatonin treatment (0.5 mg/100 g body wt.) induced release of epinephrine (E) from the adrenal medulla of newly-hatched pigeon and parakeet. In contrast, in the adults melatonin caused more than a two-fold increase in E in the pigeon, and a significant increase in the crow. Single IP melatonin injection (0.5 mg/100 g body wt.) caused hypoglycemia in the newly-hatched parakeet and adult pigeon, and hyperglycemia in newly-hatched pigeon after 0.5 h of treatment. Melatonin failed to regulate glucose homoeostasis in newly-hatched and adult crow. Splanchnic denervation of the left adrenal gland was performed in the adult pigeon. The right adrenal served as the innervated gland. Melatonin-induced modulation of catecholamines following a single IP injection (0.5 mg/100 g body wt.) revealed significant increases in NE fluorescence and NE content at 4 and 12 h after treatment in the denervated gland only, which gradually approached normal levels 9 days after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMedDate not supplied

Capacity of birds for transitive inference: the solution of the Gillan test by corvids and pigeons.

A system of four to five differentiations forming a series, in which the magnitude of the reinforcement (R) of each succeeding color stimulus was greater than the preceding by one unit, was formed in pigeons (Columba livia L.) and crows (Corvus corone cornix L.). The number of units of the R that was associated with each of the stimuli increased successively from stimulus pair to stimulus pair from one up to four to five (1st series) and from five to ten (2nd series). After the development of the system of differentiations, the capacity of the birds to compare the magnitudes of R in given new combinations of stimuli and to choose the stimulus associated with the greater R (transitive inference) was tested. Given small Rs, the pigeons and crows solved the test equally successfully; in the case of large reinforcements, the pigeons began to make random choices, while in the crows the proportion of correct choices decreased. The proportion of appropriate solutions was greater when it was a greater absolute difference between the number of units of the R to be compared. The solution of the test employed by the birds is not proof of their capacity for transitive inference, since it can be explained by their capacity for unexpected comparison of the absolute values of the R associated with each of the stimuli.

Animals↗
PubMed1983

Sexual differences in the Japanese quail: behavior, morphology, and intracellular metabolism of testosterone.

Three experiments were carried out to study whether differences in the intracellular metabolism of testosterone (T) can explain sexually differential responses to T in Japanese quail. In the first experiment, a series of dose-response curves in which length of Silastic testosterone implants was related to effects on several behavioral and physiological variables was established. In Experiment 2, adult males and females were assigned to six experimental groups: intact males and females (I-males and I-females), castrated males and females implanted subcutaneously with 40-mm Silastic implants of T (T-males and T-females), and castrated males and females without hormone treatment (CX-males and CX-females). No CX-bird (male or female) and no I-female exhibited male sexual behavior. However, I-males and T-males regularly copulated during the behavioral tests. No crowing was ever heard in CX-animals and I-females. T-females crowed less than T-males and their crowing sounded weaker than those of males. The cloacal glands of T-females were less developed than those of males. Radioimmunoassay of T and 5 alpha-DHT showed that T-males and T-females have similar plasma levels of androgens. No striking differences were observed in the way testosterone is metabolized by the pituitary gland and central nervous tissues of males and females. By contrast, the production of 5 alpha-dihydrotestosterone (5 alpha-DHT) and 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha, 3 alpha-diol) was higher in the cloacal glands of males than in those of females. These sex differences were not detected between T-males and T-females. In experiment 3, the cloacal gland of males produced more 5 alpha-reduced metabolites than those of females. The pituitary gland of females also produced more 5 beta-androstane-3 alpha, 17 beta-diol (5 beta, 3 alpha-diol). In syringeal muscles, the production of 5 beta-dihydrotestosterone (5 beta-DHT) and 5 beta, 3 alpha-diol was higher in females compared to males.

Animals↗
PubMed1991

Behavioral and hormonal correlates of social dominance in stable and disrupted groups of male domestic fowl.

An experiment was conducted to determine the behavioral and hormonal correlates of social dominance in stable and disrupted groups of male domestic fowl (Gallus domesticus). In addition, the relative importance of visual and auditory cues in the maintenance of dominance status in this species was assessed. Alpha roosters were removed from their six-bird home pens for 1 week, and placed in either (1) and adjacent pen in visual contact with penmates, (2) and adjacent pen where visual, but not auditory, contact was prevented, or (3) a different building where they were in visual and auditory isolation. Dominance rank, aggressive activity, and crowing frequency were intercorrelated during the premove period. There was a significant increase in both aggression and crowing among the males remaining in the home pen following removal of the alpha male, except in the treatment in which males were still in visual contact with the removed alpha, in which only aggression increased. Increases in crowing frequency were also noted in alpha males. High levels of aggression occurred when alpha males were returned except in those pens in which visual contact had been maintained. Visual cues thus appear to be more important than auditory cues alone with respect to the maintenance of dominant social status in roosters. There were no clear correlations between behavioral variables and plasma androgen or corticosterone levels in either the stable or disrupted flocks, and no consistent changes in the levels of these hormones as a result of experimental manipulation; several possible explanations for this finding are discussed.

Agonistic Behavior↗
PubMed1986

Effects of metabolism inhibitors, antiestrogens and antiandrogens on the androgen and estrogen induced sexual behavior in Japanese quail.

The relative contribution of androgenic and estrogenic metabolites of testosterone to the activation of sexual behavior was studied in Japanese quail by using inhibitors of testosterone metabolism, antiestrogens and antiandrogens. These compounds were tested in castrated birds whose sexual behavior had been activated by silastic implants of testosterone (T) or daily injections of testosterone propionate (TP) or diethylstilboestrol (DES). The aromatase inhibitor ATD only depressed T-induced behavior when injected at high doses and the 5 alpha-reductase inhibitor, 4MA was inactive in this respect. The antiestrogens, tamoxifen (TAM) and nitromifene citrate (CI-628) strongly depressed sexual behavior but they also drastically reduced the crowing behavior which is typically androgen-dependent which throws some doubts on the specificity of their action. The antiandrogens, flutamide and cyproterone acetate (CA), only had limited inhibitory effects on the copulatory behavior but similarly decreased only marginally the crowing. As they strongly depressed the cloacal gland growth, it can be ascertained that they were injected in sufficient amounts and their lack of action on crowing questions the ability of these compounds to inhibit brain processes even when they are androgen-dependent. Taken together with the results of previous experiments which tested the behavioral effects of the testosterone metabolites, the present data confirm the implication of both androgenic and estrogenic metabolites of testosterone in the activation of behavior. Their interaction remains, however, poorly defined and its understanding will probably require the identification of the biochemical processes which in the brain mediate the behavior.

Androgens↗
PubMed2006

Hand preference for writing and associations with selected demographic and behavioral variables in 255,100 subjects: the BBC internet study.

In an Internet study unrelated to handedness, 134,317 female and 120,783 male participants answered a graded question as to which hand they preferred for writing. This allowed determination of hand preference patterns across 7 ethnic groups. Sex differences in left-handedness were found in 4 ethnic groups, favoring males, while no significant sex differences were found in three of the groups. Prevalence of left-handedness in the largest of the ethnic groups (self-labelled as "White") was comparable to contemporary hand preference data for this group [Gilbert, A. N., & Wysocki, C. J. (1992). Hand preference and age in the United states. Neuropsychologia, 30, 601-608] but the prevalence of left-handedness in individuals >70 years of age was considerably higher in the present study. Individuals who indicated "either" hand for writing preference had significantly lower spatial performance (mental rotation task) and significantly higher prevalence of hyperactivity, dyslexia, asthma than individuals who had clear left or right hand preferences, in support of Crow et al. [Crow, T., Crow, L., Done, D., & Leask, S. (1998). Relative hand skill predicts academic ability: global deficits at the point of hemispheric indecision. Neuropsychologia, 36, 1275-1282]. Similarly, an association of writing hand preference and non-heterosexual orientation was clearest for individuals with "either" writing hand responses. We conclude that contradictions in the literature as to whether or not these variables are linked to handedness stem largely from different definitions of hand preference. Due to a lack of statistical power in most studies in the literature, the "either" hand writing preference group that yielded the most salient results in this study is not normally available for analysis.

Adolescent↗
PubMed1988

Evolution of sex in RNA viruses.

The distribution of deleterious mutations in a population of organisms is determined by the opposing effects of two forces, mutation pressure and selection. If mutation rates are high, the resulting mutation-selection balance can generate a substantial mutational load in the population. Sex can be advantageous to organisms experiencing high mutation rates because it can either buffer the mutation-selection balance from genetic drift, thus preventing any increases in the mutational load (Muller, 1964: Mut. Res. 1, 2), or decrease the mutational load by increasing the efficiency of selection (Crow, 1970: Biomathematics 1, 128). Muller's hypothesis assumes that deleterious mutations act independently, whereas Crow's hypothesis assumes that deleterious mutations interact synergistically, i.e., the acquisition of a deleterious mutation is proportionately more harmful to a genome with many mutations than it is to a genome with a few mutations. RNA viruses provide a test for these two hypotheses because they have extremely high mutation rates and appear to have evolved specific adaptations to reproduce sexually. Population genetic models for RNA viruses show that Muller's and Crow's hypotheses are also possible explanations for why sex is advantageous to these viruses. A re-analysis of published data on RNA viruses that are cultured by undiluted passage suggests that deleterious mutations in such viruses interact synergistically and that sex evolved there as a mechanism to reduce the mutational load.

Models, Genetic↗
PubMed2002

No deficits at the point of hemispheric indecision.

This study attempted to replicate a recent finding by Crow et al. [Neuropsychologia 36 (1998) 1275] showing that about equal skill of right and left hand (i.e. hemispheric indecision) is associated with deficits in cognitive and scholastic achievement. The present study assessed hemispheric indecision by using Annett's [Left, Right, Hand and Brain: The Right Shift Theory, Lawrence Erlbaum, London, 1985] peg moving test and by assessing the consistency of hand preference at school entrance. Non-verbal intelligence, reading and spelling accuracy were assessed about three years later. The sample consisted of 530 boys. Contrary to Crow et al., children with about equal hand skill did not show deficits in non-verbal intelligence, reading and spelling. Also, there were no deficits when inconsistent hand preference was taken as indication of hemispheric indecision. The findings cast doubt on the hemispheric indecision hypothesis and speak specifically against Orton's [Reading, Writing and Speech Problems in Children, Norton, New York, 1937] position, revived by Crow et al., that delayed or absent hemispheric dominance may lead to difficulties with the acquisition of reading and spelling.

Child↗
PubMed1999

The theory of an agnosic right shift gene in schizophrenia and autism.

The right shift (RS) theory (Annett, M., 1972. The distribution of manual asymmetry. Br. J. Psychol. 63, 343-358; Annett, M., 1985. Left, Right, Hand and Brain: The Right Shift Theory. Lawrence Erlbaum, London) suggests that the typical pattern of human cerebral and manual asymmetries depends on a single gene (RS+) which impairs speech-related cortex of the right hemisphere. The theory offers solutions to several puzzles, including the distribution of handedness in families (Annett, M., 1978. A Single Gene Explanation of Right and Left Handedness and Brainedness. Lanchester Polytechnic, Coventry; Annett, M., 1996. In defense of the right shift theory. Percept. Motor Skills 82, 115-137), relations between handedness and cerebral speech laterality (Annett, M., 1975. Hand preference and the laterality of cerebral speech. Cortex 11, 305-328; Annett, M., Alexander, M.P., 1996. Atypical cerebral dominance: predictions and tests of the right shift theory. Neuropsychologia 34, 1215-1227) and handedness and dyslexia (Annett, M. et al., 1996. Types of dyslexia and the shift to dextrality. J. Child Psychol. Psychiatry 37, 167-180). If Crow's (Crow, T.J. et al., 1989. Schizophrenia as an anomaly of development of cerebral asymmetry. A postmortem study and a proposal concerning the genetic basis of the disease. Arch. Gen. Psychiatry 46, 1145-1150; Crow, T.J., 1997. Is schizophrenia the price that Homo sapiens pays for language? Schizophr. Res. 28, 127-141) theory that schizophrenia is due to an anomaly of cerebral dominance is correct, and if the RS theory is correct, schizophrenia could be due to an anomaly of the RS+ gene. If the RS+ gene were at risk for a mutation which caused a loss of directional coding, the mutant could be described as 'agnosic' for left and right. Such a gene would impair either hemisphere at random. When paired with another RS+ gene, both hemispheres would be impaired in 50% of cases. The other 50% and people in whom the agnosic gene is paired with an RS-allele (neutral for asymmetry and not giving hemisphere impairment) would have one unaffected hemisphere and, thus, normal development. Quantitative predictions based on the RS genetic theory as previously developed, plus an agnosic mutant with frequency required to give schizophrenia in 1% of the population, are consistent with estimates of concordance for schizophrenia in relatives. Homozygotes of the agnosic mutant would occur at about the rate estimated for autism.

Autistic Disorder↗