Reconstruction of a first-order phase transition from computer simulations of individual phases and subphases.
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Biomedical subjects
Publications and source records attributed to M Ebeling.
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Simplified models of the protein-folding process have led to valuable insights into the generic properties of the folding of heteropolymers. On the basis of theoretical arguments, Shakhnovich and Gutin [(1993) Proc. Natl. Acad. Sci. USA 90, 7195-7199] have proposed a specific method to generate folding sequences for one of these. Here we present a model of folding in heteropolymers that is comparable in simplicity but different in spirit to the one studied by Shakhnovich and Gutin. In our model, the proposed recipe for constructing folding sequence fails. We find that, as a rule, the construction of folding sequences is impossible to achieve by looking at the native conformation only. Rather, competing conformations have to be taken into account too. An evolutionary algorithm that generates folding sequences by optimizing both stability of the native state and folding time is described. Remarkably, this algorithm produces, among others, sequences that fold reproducibly to metastable states.
We describe the convalescent care of 169 back-transported (to community hospitals) and 285 eligible but not back-transported very low birth weight (VLBW) infants. Eligible infants who were not back transported to a level I or II community hospital were transferred to a level II nursery within the Medical University of South Carolina (MUSC) for convalescent care. Study infants were admitted to the neonatal intensive care unit (NICU) at MUSC from July 1985 through June 1989. They were admitted after maternal transport to MUSC for imminent delivery (N = 159), out-born community delivery (N = 55), or in-born MUSC delivery (N = 240). The mean +/- SD birth weight and gestational age and the NICU admission diagnoses for the back-transported and non-back-transported neonates were similar. The mean +/- SD weight of neonates at the time they were back transported was significantly greater than the weight of neonates at the time of intrahospital transfer. In contrast, the discharge weight to home and total days hospitalized were significantly less in the back-transported infants. Five back-transported neonates (3%) and 12 non-back-transported neonates (4%) were readmitted to the NICU. The back-transported infants used more than 3,800 bed days at community hospitals that would otherwise have been spent in the regional center, thus facilitating increased parental and primary physician involvement in their care.
A retrospective investigation examined patterns of use of prenatal care and pregnancy outcomes (low birthweight and preterm births) in 6176 pregnancies without antepartum medical complications. Prenatal care use patterns differed significantly by mother's age, marital status, race, education, method of payment, and gravidity. By controlling for these differences through a logistic regression procedure, results showed that prenatal care was associated with significant reductions in the number of infants who were delivered preterm or had low birthweight. Fewer very low-birthweight (less than 1500 g) infants were among the preterm infants delivered to mothers with prenatal care compared with women who received no prenatal care. These data suggest that significant improvements in pregnancy outcomes are seen among women who use prenatal care, and these benefits occur in the absence of antepartum complications.
Changes in both the location of very low birth weight births and in the number of infants selected for transport were chosen for the evaluation of regionalized perinatal care and its effectiveness in the Lowcountry Perinatal catchment area. The four-year period reviewed was characterized by the initiation of a well-defined regionalized perinatal transport program at the Medical University of South Carolina. In conjunction with this increased availability of transport, there was a statistically significant (p less than 0.02) increase in the number of VLBW neonates transported to MUSC after being delivered in community hospitals. This increase was accompanied by an increase in the proportion of infants referred for transport within the first hour of life. Among those neonates referred within the first four hours of life, survival was inversely proportional to the infant's age when the transport team arrived, suggesting that a rapid response by the neonatal transport team was associated with a significantly increased VLBW infant survival. Among all transported infants, in-utero continues to be the most efficacious means of transport for VLBW infants and that delivery of VLBW infants at regional medical centers continues to result in the most optimal survival.
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OBJECTIVE: Numerous risk factors for development of retinopathy of prematurity (ROP) in very low birth weight infants have been identified in the literature. However, the role of anemia in the development of ROP has not been adequately addressed. STUDY DESIGN: We retrospectively examined the medical records of all infants weighing < or = 800 g who were admitted to a university hospital between July 1, 1992 and December 30, 1997. Highest and lowest hemoglobin and hematocrit values and the number of blood transfusions were recorded at each week of life during hospitalization. Gestational age at birth, birth weight, race, sex, oxygen status, history of bronchopulmonary dysplasia, length of hospital stay, and sepsis were also identified as potential risk factors. Data were analyzed using logistic regression to adjust for these confounding variables. RESULTS: Infants were grouped according to ROP status in the following manner: stage 0 to 1 ROP, stage 2 ROP, and stage 3 to threshold ROP. Sex, gestational age at birth, bronchopulmonary dysplasia, ventilator days, length of hospital stay, and number of blood transfusions were significantly associated with severity of ROP by univariate analysis. Using a logistic regression model, only gestational age (p = 0.007) and number of blood transfusions (p = 0.04) remained statistically significant. CONCLUSIONS: Anemia did not affect severity of ROP as an independent risk factor. However, the number of blood transfusions did affect the highest stage of ROP in this group of premature infants. Infants who remained severely anemic (Hgb < or = 8 g/dl or Hct < or = 25%) for longer periods of time developed milder ROP than less anemic infants.