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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cycling adult female hamsters can be induced to mate and ovulate 24 h early by the injection of 20 IU human chorionic gonadotropin (hCG) at 1500 h on Day 3 (day before proestrus), but pregnancy is not established. Although there is evidence of decreased sperm transport in precociously ovulated females, this does not appear to be the primary cause of infertility. Reduced size and vascularity of corpora lutea (CL) in treated females suggests incomplete or failed CL activation. Control and hCG-treated females were killed by exsanguination under ether anesthesia at intervals for the first 5 days after mating. Serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol, and progesterone were measured by radioimmunoassay. Luteinizing hormone in treated animals was very high at 2200 h on Day 1 after mating (31 h after the hCG injection), due to endogenous release, and dropped below control levels thereafter. Follicle-stimulating hormone, by contrast, was significantly lower than controls at 2200 h on Day 1 and remained low until 2200 h on Day 3 after mating. Prolactin in treated animals was not different from that in controls, except for 1000 h on Day 4, when it showed a significant dip. Estradiol in treated animals was significantly higher than in controls at 2200 h on Day 1 (when LH was also high and FSH was low), and remained high at 1000 h and 2200 h on Day 2, dropping thereafter to control levels. Progesterone was initially at control levels but had dropped significantly by 1000 h on Day 2 and remained low for the next 24 h. These results suggest that pregnancy failure is due to inadequate activation of corpora lutea. This may be due to: 1) immaturity of follicles at the time of ovulation; 2) inappropriate timing of preovulatory events; 3) the luteolytic effects of high levels of LH or estradiol or both; 4) the low level of FSH in the early stages of corpus luteum development; or 5) a combination of the above. Abnormalities of prolactin secretion were not investigated in detail but cannot be ruled out at this time.
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PMID:Multiple causes of pregnancy failure in hamsters precociously ovulated by human chorionic gonadotropin. 393 83

Plasma renin (PRC) and aldosterone concentrations are known to be high during early postnatal life. Whether this is related to the low rates of renal blood flow or to sodium homeostasis remains unknown. Measurement of PRC, renal blood flow, and its intrarenal distribution were performed in 1- to 3-wk-old puppies subjected to maneuvers known to stimulate or inhibit renin release. In the awake state, PRC was observed to be higher in 2-wk-old puppies than in older or younger dogs, (P less than 0.0001). Significant differences in PRC were also found between litters (P less than 0.0001), but they did not account for the age-related changes. Anesthesia resulted in a 3- to 5-fold rise in PRC, whereas saline expansion suppressed PRC at all ages, the fall tending to become progressively greater with age (P less than 0.09). There was no significant correlation between the age-related changes in PRC and those in renal blood flow or its intrarenal distribution. The results of these experiments demonstrate that in the newborn from a qualitative point of view, PRC changes appropriately in response to various stimuli. However, quantitative age-related differences exist in this regard, reflecting an initial immaturity of the feedback system.
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PMID:The renin angiotensin system in newborn dogs: developmental patterns and response to acute saline loading. 699 Mar 67

We gave special attention to these very fragile newborns in whom associated pathology was often present. We were faced above all by respiratory and hemodynamic problems. Pre-operative care is essential and must be adapted to the degree of emergency. The newborn must reach the operating room in normothermia, normoxia and in adequate metabolic status. The anaesthesia technique used was always simple with few anaesthesics and ventilation controlled manually and mechanically after intubation. Scrupulous monitoring was always the case. Principal anaesthesic incidents included hypothermia and tachycardia. A precise cause was linked to the 13 accidents encountered. In 8 cases slow decurarisation was noted. Special comments must be made about the premature infant's possibilities versus pharmacocinetic of anesthesics, hemodynamic modification, hyperbi lirubinemia hepatic and renal enzymatic immaturity. Thus we think the anesthesiologist must be specifically trained for the care of these patients.
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PMID:[Anesthesia of the newborn weighing less than 2000 g, 100 cases (author's transl)]. 733 97

The choice of anesthesia during pregnancy and fetal operations is controversial. Halothane frequently is used, but its direct effects on fetal cardiac performance are unknown. The effects of halothane on fetal cardiac mechanics were studied in 8 fetal lamb hearts (135 days' gestation) using a modified Langendorff model connected to a membrane oxygenator. The perfusate consisted of oxygenated maternal blood at a constant flow temperature, hematocrit value, and glucose level. Coronary blood flow, left ventricular systolic pressure, left ventricular end-diastolic pressure, and the developed left ventricular pressure at a fixed volume were evaluated at baseline and after the addition of incremental concentrations of halothane to the perfusate through the oxygenator. Perfusate halothane levels were maintained in a clinical range. Systolic and diastolic cardiac function were adversely affected by the administration of even low doses of halothane, despite a concomitant increase in coronary blood flow. Because of the immaturity of their calcium transport system, fetal hearts may be particularly sensitive to the known calcium channel-blocking properties of halothane.
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PMID:Effects of halothane on the immature lamb heart. 788 14

Physiological immaturity of the respiratory musculature and central respiratory control centres leads to an increased risk of apnoea and respiratory complications following general anaesthesia in neonates. Regional anaesthetic techniques may obviate the need for general anaesthesia and lessen the risks of perioperative morbidity. Although these techniques have been described in infants, previous reports have dealt with single-shot techniques for brief surgical procedures (< 60 min). Experience with prolonged operative cases using regional anaesthesia via indwelling catheters in infants is limited. We present our experience with four infants in whom either caudal epidural or spinal anaesthesia was administered via indwelling catheters for operative procedures that lasted 90 to 180 min. We believe this technique is an alternative to general anaesthesia in these patients.
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PMID:Continuous regional anaesthesia in infants. 826 68

The physiologic immaturity of respiratory musculature and central respiratory control centers leads to an increased risk of apnea and respiratory complications following general anesthesia in the neonate. Regional anesthetic techniques such as spinal and caudal epidural anesthesia may obviate the need for general anesthesia and lessen the risks of perioperative morbidity. Although these techniques have been previously described in infants, the majority of reports focus on regional anesthesia during herniorrhaphy in the former, preterm infant. There is relatively little or no information concerning regional anesthesia during urologic surgery in infants, especially during the actual neonatal period (0 to 28 days). We report on three neonates (2.17 to 3.8 kg) who required anesthetic care during the neonatal period for various urologic procedures including cystoscopy, incision of a ureterocele, and vesicostomy placement. Either caudal or spinal anesthesia was successfully used in the awake infant without the need for supplemental anesthetic agents (intravenous or inhalational). The advantages, risks, and applications of regional anesthesia during urologic surgery in the neonate are reviewed.
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PMID:Neonatal regional anesthesia: alternative to general anesthesia for urologic surgery. 847 Mar 25

We surveyed 352 physicians board certified in neonatal-perinatal medicine on their attitudes and practices in the area of pain and pain management in neonates and infants. In contrast to earlier surveys of this type, almost all respondents indicated that even the youngest and most premature infants are able to perceive pain, and most reported that they always advocated anesthesia during the intraoperative period. The use of analgesic agents in the postoperative period, however, was more variable. Respondents who indicated that neonates perceived less pain than adults reported seeing fewer signs of pain and using less analgesia in the postoperative period. They were also more likely to believe that analgesics are too dangerous to use in neonates and that physiologic factors such as incomplete myelination of the pain pathways and neural/physical immaturity (factors now known not to play a role) contribute to diminished pain sensitivity. Conversely, respondents who indicated that neonates do not perceive less pain than adults, the majority of respondents, reported seeing more signs of pain and using more medication in the postoperative period. These physicians also believed that the physiologic stress associated with pain can be more dangerous than the analgesics. We conclude that attitudes and reported practices have changed in the area of neonatal pain and pain management. Furthermore, our data indicate that these attitudes significantly predict reported postoperative medicating practices.
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PMID:Neonatal pain: a comprehensive survey of attitudes and practices. 848 95

A 480 g, 38-day-old female infant underwent ventriculo-peritoneal shunt surgery for hydrocephalus after intra-ventricular hemorrhage. The patient was born at a gestational age of 25 weeks and 5 days, weighing 600 g, as one of twins by a cesarean section. Although respiratory distress syndrome developed, it was relieved with surfactant. The esophagus was easily perforated by a gastric tube. At the age of 7 days, PDA was closed conservatively with indomethacin. Anesthesia was induced and maintained with fentanyl (induction dose 4 micrograms.kg-1, total dose 6 micrograms.kg-1) and vecuronium. Ventilation was controlled with oxygen and air (FIO2 0.21-0.25). The main problems encountered by anesthetists in the perioperative period were; fluid management (hyperkalemia, hyponatremia, infusion volume), bradycardia due to increased intracranial pressure, body temperature control (hypothermia), and transport to the operating room. In anesthesia for extremely low birth weight (extremely premature) infants, utmost care and proficient procedure are required because of their immaturity, fragility and smallness.
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PMID:[Anesthetic problems in a 480 g infant for ventriculo-peritoneal shunt surgery]. 886 31

Hematopoietic progenitor cells are present in umbilical cord blood; placental blood (PB) previously considered as waste product now constitutes an alternative source of hematopoietic stem cells for bone marrow reconstitution. This has promoted the establishment of cord blood banks for use in unrelated transplants. The banking of PB offers many advantages: the donors do not require anesthesia, stored PB can be a valuable source of stem cells for patients from ethnic minorities underrepresented in volunteer registers, and stored PB can be made available much faster than bone marrow from unrelated donors. Preliminary clinical experience suggests that, due to the immunological immaturity of PB cells, graft versus host disease might be lower than when using bone marrow from adult donors and HLA restrictions might be less stringent. If the number of nucleated cells in PB often appears low for patients weighing more than 40 kg, clinical data suggest that the number of stem cells may be sufficient for adult transplantation. The number of cord blood banks throughout the world is increasing rapidly. In the USA and Europe, more than 10,500 PB units are stored and available for transplantation. In the next 5 years, a total of 50,000 PB will be reached which may be sufficient to provide for the majority of candidates for unrelated BM transplantation. The practices of umbilical cord blood collection, mother selection, infectious disease screening, cell manipulation and storage must be standardized. Some accreditation process should be mandatory for assessing operating procedures and the quality assurance programs of the banks, and for allowing the international exchange of placental blood between transplant centers.
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PMID:[Cord blood banks--unrelated transplants]. 957 80

We determined the conditions (immaturity, species, anesthesia, receptor blockade selectivity) under which glutamate receptor blockade produces respiratory depression in mammals. In unrestrained 0- to 2-day-old neonate and adult mice and cats, ventilation was measured by the barometric method, before and after separate or sequential administration of a non-NMDA receptor antagonist, NBQX (2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(F)quinoxaline, 2-200 mg kg(-1) in mice, 10-40 mg kg(-1) in cats), and a NMDA receptor antagonist, dizocilpine (3 mg kg(-1) in mice, 0.15-1.0 mg kg(-1) in cats). NBQX or dizocilpine alone did not decrease ventilation in awake adults, but NBQX strongly depressed ventilation in neonate awake mice and in adult anesthetized animals. Given together, dizocilpine and NBQX always profoundly depressed ventilation by producing a lethal apnea in neonate mice, and an apneustic pattern of breathing in adults of both species and in neonate cats. We conclude that blockade of either NMDA or non-NMDA receptors is innocuous in awake adults. The factors which may potentiate respiratory depression are (1) anesthesia, (2) immaturity, and (3) combined blockade of both receptors types. The mechanism of depression is species-dependent and age-dependent.
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PMID:Respiratory effects of glutamate receptor antagonists in neonate and adult mammals. 965 39


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