Development of estrous synchronization protocols using melengestrol acetate in Bos indicus cattle.

Five experiments were conducted on commercial farms in Brazil designed to develop the basis for an estrus synchronization protocol using melengestrol acetate (MGA) in Bos indicus cattle. These studies resulted in the development of the following protocol: 0.5 mg x d(-1) of MGA between d -14 and -1; 2.0 mg i.m. injection of estradiol cypionate on d -9; 48 h temporary weaning between d 0 and 2; and natural service beginning on d 0. The basis of this protocol was to induce estrous cyclicity before postpartum loss of body condition, prevent premature luteolysis, eliminate the need for labor required to detect estrus, and consequently increase the likelihood of pregnancy early during the postpartum period. This treatment effectively induced estrous cyclicity among anestrous cows, synchronized estrus activity, and prevented premature luteolysis with no negative effect on pregnancy.

Analysis of human chromosome 21: correlation of physical and cytogenetic maps; gene and CpG island distributions.

Human chromosome 21 has been analyzed by pulsed-field gel electrophoresis using somatic cell hybrids containing limited regions of the chromosome and greater than 60 unique sequence probes. Thirty-three independent NotI fragments have been identified, totalling 43 million bp. This must account for essentially the entire long arm, and therefore gaps remaining in the map must be small. The extent of the pulsed-field map has allowed the direct correlation of the physical map with the cytogenetic map: translocation breakpoints can be unambiguously positioned along the long arm and the distances between them measured in base pairs. Three breakpoints have been identified, providing physical confirmation of cytogenetic landmarks. Information on sequence organization has been obtained: (i) 60% of the unique sequence probes are located within 11 physical linkage groups which can be contained in only 20% of the long arm; (ii) 9/21 genes are clustered within 4%; (iii) translocation breakpoints appear to occur within CpG island regions, making their identification difficult by pulsed-field techniques. This analysis contributes to the human genome mapping effort, and provides information to guide the rapid investigation of the biology of chromosome 21.

Breath hydrogen excretion in normal newborn infants in response to usual feeding patterns: evidence for "functional lactase insufficiency" beyond the first month of life.

Sequential studies of morning breath hydrogen excretion were carried out in the homes of 16 normal breast-fed or formula-fed infants during the first 5 months of life. Except for two infants whose stools did not produce H2, all infants had elevated breath H2 excretion (greater than 10 parts per million) during and after the first month of life. There was a significant relationship to age (P less than 0.005) for all three measures of H2 excretion (4-hour average, peak, and preprandial), with mean values being highest in month 2, elevated but lower in month 1, and dropping significantly in months 3 and after. Additional 24-hour studies with six 7-week-old infants demonstrated that H2 excretion was inversely related to state of arousal, more likely to be detected in the afternoon, and not clearly related to time of feeding. These findings suggest that incomplete lactose absorption in response to usual feeding patterns persists beyond the first months of life in all infants. The pattern of breath H2 excretion indicates a probable developmental change in quantity and consistency of carbohydrate substrate delivered to colonic flora. Although elevated breath H2 excretion in response to normal feeding demonstrates incomplete absorption, it should not be used to determine an infant's status as a "lactose malabsorber."