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Query: UMLS:C0728731 (prematurity)
 7,134 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rosenblueth's hypothesis states that atrioventricular (AV) nodal conduction delay and Wenckebach periodicity of AV transmission are not due to overall decremental conduction within the AV node but are due to a single step delay which is caused by a special element or layer of the AV nodal tissue. This paper discusses some theoretical considerations which allow detailed evaluation of the original hypothesis. Two artificial conduction structures which incorporate the Rosenblueth phenomenon are presented and tested by theoretical experiments that consider the potential of these structures to produce (a) basic pattern of Wenckebach periods, (b) decremental shortening of RR intervals during Wenckebach periods. These experiments are also employed to test whether or not the Rosenblueth concept can be used to explain (c) appropriate dependence of AV conduction changes on the prematurity of atrial depolarizations, and of (d) alternating cycle lengths such as may be seen with atrioventricular reentrant tachycardia. The results of the theoretical considerations show that the original concept of the Rosenblueth hypothesis is sufficient to explain (a) but it cannot be used for realization of (b), (c) and (d). A modification of the original concept complying with both (a) and (b) is proposed. This modified structure can also reproduce (c), but not simultaneously with (b). The experiments show that anisotropy of intra AV nodal conduction may create an electrophysiological mechanism of single-step delay. Different anisotropic conduction structures have to be considered to reproduce phenomenon (d).
Pacing Clin Electrophysiol 1988 Sep
PMID:Theoretical evaluation of the Rosenblueth hypothesis. 246 Aug 28

Interleukin-2 receptors (IL-2R) on mononuclear cells from human umbilical cord blood were investigated after stimulation by phytohemagglutinin (PHA) and anti-CD3 antibody. The proportion of cells expressing the Tac antigen (IL-2R alpha, p55) did not differ from that for adult mononuclear cells. However, the levels of high affinity IL-2R (H-IL-2R) and low affinity IL-2R (L-IL-2R) present on the PHA blasts of cord blood cells were shown to be twice and three times, respectively, that of adults by interleukin-2 (IL-2) binding assay. The level of low affinity IL-2R in the cord blood cells was approximately double that of adult cells after activation by anti-CD3 antibody, but no difference was observed in the levels of high affinity IL-2R. Functional investigation of IL-2R revealed that the amount of internalized IL-2 in PHA-stimulated cord blood mononuclear cells was twice that in adult mononuclear cells but there were no differences between them in the time course of internalization and degradation. Although there were significant numbers of H-IL-2R in premature (25 and 28 weeks) infants following PHA stimulation, there were markedly fewer following anti-CD3 stimulation. Prematurity of the T-cell activation system through the CD3 pathway at this stage is therefore indicated.
J Reprod Immunol 1989 Sep
PMID:IL-2 receptor expression and function on human cord blood mononuclear cells following PHA and anti-CD3 antibody stimulation. 253 55

A pilot study was begun in Hong Kong to prove feasibility and the advantage of a low-budget surveillance program. A questionnaire was developed for reporting all perinatal deaths including a minimum gestational age of 22 completed weeks and/or a birth weight of 500 g. Coordinators were appointed for every maternity unit. Replies were sent by mail to the Obstetrical and Gynecological Society. Using volunteer time, the data were collected and analyzed. A total of 25 units participated; 4 University, 6 government, and 15 private. During the 1st study year, there were 535 perinatal deaths, which represented 90% of the total perinatal deaths for Hong Kong. The overall perinatal mortality rate (PNM) was 8.1/1000; highest in government, lowest in private units (5.1). The University units, which admitted most of the high-risk mothers, had a PNM rate of 8.6/1000. The most common causes of perinatal deaths were congenital anomalies, intrauterine death of unknown cause, and prematurity. There was a significant difference when the perinatal deaths were compared in the 3 types of units; a lower incidence in twin pregnancy in University units; a higher incidence among mothers with no prenatal care in University units, more deliveries by midwives in Government units, and the high prevalence of cesarean section in private units. Suggestions are given to decrease deaths from congenital anomalies, prematurity, and stillbirth of unknown cause. The comparison among the 3 types of hospitals is only superficial.
Int J Gynaecol Obstet 1989 Sep
PMID:Developing professional responsibility in maternity care in Hong Kong. 257 70

A boy aged 2 years, born prematurely to Gipsy parents, presented with hypopigmentation severe encephalopathy with athetoid movements, bilateral ocular anomalies including cloudy corneas, iris atrophy and cataracts, as well as dental defects. Ultrastructural examination of the skin disclosed scare melanosomes. Although the neurologic and ocular anomalies might have been accounted for by his extreme prematurity, their association with hypomelanogenesis and dental defects support, in this patient the diagnosis of the oculocerebral hypopigmentation syndrome (Cross syndrome).
Acta Paediatr Scand 1989 Sep
PMID:Oculocerebral hypopigmentation syndrome (Cross syndrome) in a Gipsy child. 259 92

Records were reviewed of all patients with premature rupture of the membranes (PROM) at or less than 34 weeks estimated gestational age (EGA) who delivered at University Hospital of Jacksonville, Florida, during 1987. That year 132 patients were identified, 3.1% of all deliveries. The mean time from membrane rupture to delivery was three days, and the duration of PROM seven or more days in 9% of cases. Chorioamnionitis was diagnosed in 20% of the mothers. Delivery was by cesarean section in 30% of cases, twice the primary rate at University Hospital for 1987. Sixty-five percent of infants were male, and 13 males and four females of the 132 infants died before or after birth, the majority due to prematurity. Respiratory distress syndrome (RDS) was found in 35 infants and in 80% of these cases the membrane ruptured at 30 weeks or less. Intraventricular hemorrhage (IVH) was diagnosed in 8% of cases. Neonatal sepsis was a common diagnosis (41% of deliveries) with incidence being similar at all gestational ages. The length of membrane rupture was not statistically significant when compared with neonatal sepsis (P = 0.39).
J Fla Med Assoc 1989 Sep
PMID:Premature rupture of membranes prior to 34 weeks gestational age. One year experience at a tertiary center. 261 60

A case-controlled epidemiologic study on the risk factors leading to prematurity and IUGR was carried out in 7 rural areas in Shunyi County, Beijing. 88 prematures, 83 IUGR and 509 normal controls were included in this study and 142 factors have been taken into consideration. The result revealed that strong or abrupt physical and psychic stroke to the gravidae were the main risk factors for prematurity while maternal poor health and malnutrition played a leading role in IUGR. Deficient in-take of various diet constituents might also play a part in both prematurity and IUGR Preventive measures, based on this study are postulated.
Zhonghua Fu Chan Ke Za Zhi 1989 Sep
PMID:[An epidemiologic study of the risk factors leading to prematurity and intrauterine growth retardation]. 262 May 77

This paper reports the first part of a three-part study of developmental defects of tooth enamel in a pediatric hospital population. The dental records of 8411 children who were discharged from the Department of Dentistry at the Royal Children's Hospital, Melbourne, Australia, between 1960 and 1987 were divided into an experimental group of 7518 patients comprising 25 groups of medical conditions, and a control group of 893 children who had dental disorders only. The aim of the study was to investigate the prevalence of hypoplastic and severe-opacity developmental defects of tooth enamel (DDE), in children and adolescents with major medical disorders, and to compare the prevalence with that in the control group of normal children. The prevalence figures obtained for the different medical conditions in this study agreed generally with those of other recent investigators. The high prevalence of defects found in Rubella Embryopathy children (81.8%) and in children with Prematurity alone (56.5%) is surprising, whereas the prevalence of 27.9% defects in Clefts of Lip and Palate and 26.4% defects in Clefts of Lip and Alveolus are probably well below the true prevalence. The control group prevalence was 9.3%, which is higher than in some other studies of 'normal' children. A pediatric hospital is a most useful source of fully documented medical and dental histories for the investigation of possible relationships between medical disorders and developmental defects of tooth enamel. The control group prevalence was 9.3%, which is higher than in some other studies of normal children. A pediatric hospital is a most useful source of fully documented medical and dental histories for the investigation of possible relationships between medical disorders and developmental defects of tooth enamel.
Adv Dent Res 1989 Sep
PMID:Prevalence of developmental defects of tooth enamel (DDE) in a pediatric hospital department of dentistry population (1). 264 Apr 22

During the 7-year period from 1980 to 1986, 56 neonates with gastrointestinal (GI) perforation were treated in the Hospital for Sick Children, London. The overall mortality rate was 30%. The highest mortality rate (60%) was associated with gastric perforation, which in this series occurred only in premature neonates. Colorectal perforation carried the lowest risk of mortality (17%). The mortality rate from small bowel perforation was 35%. Prematurity and low birth weight were significant factors increasing the mortality rate from neonatal intestinal perforation. The predominant cause of perforation in the small and large intestine was necrotizing enterocolitis and the most common site of perforation was the terminal ileum. Mechanical ventilation was thought to be the cause of the perforation in four of the five neonates with gastric perforation. Primary anastomosis is a definite option in neonates who are stable intraoperatively. The mortality rate and in-patient stay for neonates who had primary anastomosis were less than for those who had stomas.
J Pediatr Surg 1989 Sep
PMID:Neonatal gastrointestinal perforation. 267 91

Twenty cases of fetal death complicating a multiple pregnancy after 20 weeks' gestation are reviewed. We evaluated gestational age at diagnosis and delivery (29.3 +/- 0.7 and 31.8 +/- 0.9 weeks, respectively), interval from diagnosis to delivery (2.6 +/- 0.6 weeks), and cause of fetal death as a group and by type of placentation (76.5% monochorionic). Eighty-five percent of the surviving fetuses were delivered preterm, and the four neonatal deaths were all due to extreme prematurity, with a mean (+/- SEM) birth weight of 794 +/- 237 g. Perinatal mortality was 585 per 1000, 450 for twin A and 750 for twin B. The causes of fetal death varied. Maternal disseminated intravascular coagulation was not diagnosed in any pregnancy in the present series. The high risk of complications related to preterm birth, compared with the low risk of problems related to continuation of a multiple pregnancy after diagnosis of a fetal death, argues in favor of conservative management in this setting.
Obstet Gynecol 1989 Sep
PMID:Multiple pregnancy with late death of one fetus. 276 7

Necrotizing enterocolitis (NEC), a disease associated with prematurity, carries a significant morbidity and mortality. This study was designed to evaluate our progress in dealing with NEC both medically and surgically in a single large neonatal intensive care unit (NICU). We also sought to confirm the relation of birth weight and particular indications for operation to outcome. Over 6 1/2 years, there were 7,807 admissions to a large NICU. Though there has been a steady increase in total admissions, especially of infants weighing less than 1,000 gm, survival has improved significantly in all groups (mean 89.1%). NEC occurred in 358 infants (4.6%), and 115 (32%) required surgical intervention. Infants weighing between 751 and 1,000 gm had the highest incidence of NEC. There has been a significant decrease in the mortality of both medically and surgically treated infants with NEC; in both cases, this decrease is weight-dependent. We found that using erythema and edema of the abdominal wall and a fixed-loop roentgenographic pattern as early indicators of necrotic bowel significantly improves survival in surgically treated infants.
South Med J 1989 Sep
PMID:Necrotizing enterocolitis: improving survival within a single facility. 277 78


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