Amoxicillin and clavulanic acid vs ceftazidime in the surgical extraction of impacted third molar: a comparative study.

The objective of this work is to compare the effectiveness and the side effects of two different drugs, amoxicillin and clavulanic acid vs ceftazidime, used as antibiotic prophylaxis in the surgical extraction of third molars and to demonstrate that the use of second choice antibiotic has no significant advantages in comparison with a first choice antibiotic. One hundred and seven patients with impacted third molar were selected and divided into two groups: amoxicillin and clavulanic acid were administered to group 1 and ceftazidime to group 2 for five days after surgery and we observed the postoperative period. The statistical analysis showed no differences between the two groups which lead to the conclusion that there is no indication to routinely administrate intramuscular second-choice antibiotic prophylatic therapy (ceftazidime) in case of surgical extraction of the third molar.

Developmental instability and right shift theory hypotheses concerning correlates of familial sinistrality: negative findings.

Both the right shift (Annett, 1985) and developmental instability (Yeo & Gangestad, 1993) theories of handedness predict that familial sinistrality (FS) should relate to hand skill asymmetries (HSA) on peg-moving tasks. Annett also hypothesises that both HSA and a procedure she derived for classifying individuals according to the pattern of their hand preferences for different manual activities can index the genotypes posited in her theory, i.e. she believes these variables are highly correlated. These hypotheses were tested in a sample of 280 dextral college students. Results failed to support the finding of Gangestad and Yeo (1994) that subjects showing greater hand skill asymmetry deviations from typical asymmetry had a greater probability of having a left-handed parent. There was also no support for Annett's finding that greater dextrality, as defined by her hand preference classification system, was negatively associated with familial sinistrality. Additionally, the relationship between HSA and Annett's hand preference classes was found to be exceedingly weak, contrary to Annett's theorising. These and other failures to find highly replicable differences between FS- and FS+ dextrals cast doubt on the validity of genetic or partial-genetic theories of handedness that posit a ''penetrance'' of a recessive non-dextrality-favouring gene that causes presumed dextral heterozygotic persons to differ from presumed homozygotic dominant persons in cognitive or manual skills.

Family size, miscarriage-proneness, and handedness: tests of hypotheses of the developmental instability theory of handedness.

The handedness theory of Yeo and Gangestad (1993) posits that moderate right-handedness is the modal manifestation of genetic handedness and that ''developmental instability'' produces deviations from modal handedness. It is also suggested (1) that sinistral parents may produce fewer offspring than do dextral parents; and (2) that sinistral mothers may be more prone to miscarriages than are dextral mothers. In line with these hypotheses, Gangestad et al. (1996) reported that a human leukocyte antigen (B8) was related to both left-handedness and to reduced offspring number in their study. They also found that left-handedness was related to the human leukocyte antigen DR3, and Yeo and Gangestad (1998) noted that this antigen has been found by Christiansen et al. (1996) to be associated with an increased risk of spontaneous abortion in women. We assessed the first hypothesis through a study of the family sizes of 2083 families with two right-handed parents and 502 families having one or more left-handed parents; we assessed the second hypothesis from miscarriage history data supplied by 300 dextral and 52 sinistral mothers. Results supported the developmental instability theory with respect to the hypothesis regarding family size, but not with respect to the hypothesis regarding miscarriage-proneness.

Failure to support the right-shift theory's hypothesis of a 'heterozygote advantage' for cognitive abilities.

Annett's (1985) 'right-shift' theory of language dominance and handedness posits three genotypes, rs++, rs(+)- and rs(-)-, and Annett has hypothesized that there are cognitive ability correlates of these genotypes. The rs++ genotype person is held to be 'at risk' for maldevelopment of spatial or other right hemisphere-based cognitive abilities, and the rs(-)- genotype individual is held to be at risk for maldevelopment of phonological abilities. Noting that there must be some adaptive advantage conferred by the heterozygous genotype for it to have survived over a presumably long period of evolution, Annett has hypothesized that heterozygotes are afforded an adaptive advantage over homozygotes because of their freedom from 'risks' to intelligence generally. Annett and colleagues have used two different indices, or markers, from which they have inferred differing concentrations of the three genotypes within groups of participants. One marker, based on responses to hand preference items of the Annett Handedness Inventory, was found by Annett (1992) to support her theory in that the least dextral of right-handed participants did best on spatial tests. The other marker Annett has used is based on the degree of right-hand advantage on a simple peg moving speed task. The present study utilized both methods and studied the performances of 259 dextral college men and women on two tests of mental rotation ability and two tests of verbal abilities. Results were not supportive of the heterozygote advantage hypothesis, and suggested that visuospatial ability was modestly related to greater dextrality of participants.