Obesity may impair lactogenesis II.

Data from livestock species and experimental animal models suggest that excess body fatness may impair lactogenesis. For example, it has long been known that overfed dairy cows are at risk of fat cow syndrome, a condition characterized by lactation failure in the early postpartum period. Obese rats often lose their litters in the early postpartum period to primary lactation failure. A negative association between high body mass index (BMI) before conception and the duration of lactation has been documented in studies from diverse human populations. Findings from our laboratory establish that among women who ever attempted to breastfeed their infants, high BMI before conception was also associated with failure to initiate breastfeeding successfully. In a more recent study, we found that high prepregnant BMI was specifically associated with later onset of lactogenesis II. This was mediated by parity but not by breastfeeding behavior. Psychosocial factors related to a woman's intention to breastfeed and her planned duration of breastfeeding did not modify this association. Taken together, these findings in animals and women strongly suggest that maternal obesity in the perinatal period is a cause of delayed lactogenesis.

Presenilin-1-associated abnormalities in regional cerebral perfusion.

OBJECTIVE: To investigate the influence of the presenilin-1 gene (PS-1) mutation on regional cerebral perfusion, SPECT was evaluated in 57 individuals. The subjects were members of a large pedigree from Colombia, South America, many of whom carry a PS-1 mutation for early-onset AD. METHODS: Members of this large kindred who were cognitively normal and did not carry the PS-1 mutation (n = 23) were compared with subjects who were carriers of the mutation but were asymptomatic (n = 18) and with individuals with the mutation and a clinical diagnosis of AD (n = 16). Cerebral perfusion was measured in each subject using hexamethylpropyleneamine oxime SPECT. The data were analyzed in two ways: 1) Mean cerebral perfusion in each of 4320 voxels in the brain was compared among the groups using t-tests (t-maps); and 2) each individual received a weighted score on 20 vectors (factors), based on a large normative sample (n = 200), using a method known as singular value decomposition (SVD). RESULTS: Based on t-maps, subjects with the PS-1 mutation who were asymptomatic demonstrated reduced perfusion in comparison with the normal control subjects in the hippocampal complex, anterior and posterior cingulate, posterior parietal lobe, and anterior frontal lobe. The AD patients demonstrated decreased perfusion in the posterior parietal and superior frontal cortex in comparison with the normal control subjects. Discriminant function analysis of the vector scores derived from SVD (adjusted for age and gender) accurately discriminated 86% of the subjects in the three groups (p < 0.0005). CONCLUSION: Regional cerebral perfusion abnormalities based on SPECT are detectable before development of the clinical symptoms of AD in carriers of the PS-1 mutation.

Maternal obesity and breast-feeding success in a rural population of white women.

Maternal obesity interferes with the initiation and maintenance of lactation in animal models but it has not been investigated widely in women. We reviewed medical records from a white population to examine the relation between prepregnant overweight [body mass index (BMI; in kg/m2) 26.1-29.0] and obesity (BMI > 29.0) on initiation and duration of breast-feeding. Logistic regression revealed that of those who ever put their infants to the breast (n = 810), women who were overweight [odds ratio (OR) = 2.54, P < 0.05] or obese (OR = 3.65, P < 0.0008) had less success initiating breast-feeding than did their normal-weight counterparts (BMI < 26.1). Proportional-hazards regression revealed higher rates of discontinuation of exclusive breast-feeding in overweight (RR = 1.42, P < 0.04) and obese (RR = 1.43, P < 0.02) women and higher discontinuation of breast-feeding to any extent in overweight (RR = 1.68, P < 0.006) and obese (RR = 1.73, P = 0.001) women. Controlling for parity, socioeconomic status, maternal education, and other factors that often covary with maternal obesity and breast-feeding did not change these results. These results suggest that excessive fatness in the reproductive period may inhibit lactational performance in women.

Analyses of response patterns clarify lead effects in olfactory reversal and extradimensional shift tasks: assessment of inhibitory control, associative ability, and memory.

Rats exposed to lead (Pb) chronically from conception were tested on (a) an olfactory serial reversal task and (b) an extradimensional shift (EDS) task. Pb exposure did not impair learning of the original olfactory discrimination but did impair learning of the 5 reversals and the EDS task. In the reversals, Pb exposure tended to shorten the initial period of persistent responding to the previously correct cue, but significantly prolonged the postperseverative learning phase (both the "chance" and "greater-than-chance" components). These effects are similar to those produced by lesions of the amygdala, a structure implicated in the process by which stimuli acquire incentive value. This similarity, coupled with the pattern of findings, suggests that Pb-induced impairment of reversal learning is due to a deficiency in learning the new contingencies of the task (an associative deficit), not inflexibility or deficient inhibitory control. These findings also illustrate the importance of analyzing the types of errors committed, rather than focusing solely on learning rate.