摘要:

SummaryThe effects of orally administered gentamicin and colistin on stool bacterial flora and overall antibiotic sensitivity patterns were evaluated in 100 newborns at risk for neonatal necrotizing enterocolitis. Gentamicin (2.5 mg/kg q6h) and colistin (1 mg/kg q6h) were administered to randomly selected groups of 50 newborns for 3 wk after birth during an 11-month study period. Stools were collected on days 1, 11, and 21 and cultures were grown under aerobic conditions on three different media.Staph. epidermidiswas the most common predominant organism in both antibiotic groups, whereasE. coliandKlebsiellawere the most common Gram-negative bacteria isolated. Seventeen % of these Gram-negative species were resistant to colistin and 9% to gentamicin, with a gradual increase occurring during the 3-wk period. On the basis of 980 positive cultures from all sites in babies in the nursery during the 11-month study,E. colisensitivity to kanamycin and gentamicin ranged between 92% and 100% except for one month midway through the study when sensitivity to kanamycin was at 80% and then returned to the 92–100% range. Klebsiella sensitivity to both aminoglycosides remained greater than 95% throughout. The incidence of neonatal sepsis remained consistent at seven to nine per 1000 live births during the study. One baby of 50 in the gentamicin group developed necrotizing enterocolitis at 5 wk of age; 0/50 in the colistin group had necrotizing enterocolitis (not significant).SpeculationThe results suggest that the use of oral antibiotics in a limited segment of the newborn nursery population may not have significantly adverse effects on the overall incidence of bacterial resistance to antibiotics and incidence of sepsis.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryAlterations in thermoregulatory mechanisms related to sleep state may play an important role in the problems of homeostasis experienced by the premature infant. In the adult, homeothermic regulation of body temperature may be suspended during REM. We measured oxygen consumption (&OV0312;O2) in six premature infants 33–35 wk gestation both at thermoneutrality and during a mild thermal stress to determine whether thermoregulatory responses were intact during REM sleep. All infants were studied under radiant warmers. Skin temperature was allowed to fall 7–8 times during a 6–8 h study period while &OV0312;O2, &OV0312;CO2, heart rate and TcPO2were continuously recorded. Sleep state was scored using EEG, EOG, EMG and behavioral criteria. A total of 1,162 one-min epochs were scored. In all states including REM, &OV0312;O2was significantly higher during the cool periods. The mean increases: 21.5%, 23.3%, 11.1% and 5.3% for Awake, Indeterminate, REM and NREM respectively. When REM and NREM were compared at thermoneutrality, there was no difference in the &OV0312;O2(8.80 ± 0.11 and 8.93 ± 0.15 cc/kg/min, mean ± S.E., for REM and NREM, respectively). We conclude that in contrast to the adult, active thermoregulation occurs in the premature infant during REM sleep.SpeculationIn the adult, the reason for temporary poikilothermy during REM sleep is unknown. Some have considered this phenomenon a regression to a phylogenetically primitive condition which is necessary for normal hypothalamic function. Because the newborn period is characterized by profound ontogenic change, it is reasonable to speculate that the difference we observed between the premature and the adult is due to a developmental phenomenon. We further suggest that this developmental process may serve to protect the premature infant during REM sleep from extended periods of poikilothermy.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryThe adsorption of aqueous phospholipid dispersions containing dipalmitoyl phosphatidylcholine (DPPC) is investigated at 35–37°C as a function of dispersion preparation technique. Systems studied in terms of surface pressure-time (π-t) adsorption behavior were pure DPPC, 9:1 DPPC:dipalmitoyl phosphatidylethanolamine, 7:3 DPPC:egg phosphatidylglycerol (PG), and lipids extracted from cow lung lavage. The results show that π-t characteristics can differ significantly depending on the technique by which the DPPC-containing mixtures are initially dispersed in 0.15 M NaCl solution. Examples of path dependence include the fact that DPPC, which will not adsorb at T = 35°C when placed in powdered crystals on the subphase surface, exhibits measurable π-t changes after subphase dispersion by sonication or by mechanical vortexing. For 7:3 DPPC:PG, dispersion by sonication on ice or by mechanical vortexing gives faster adsorption than dispersion by sonication without temperature control. The effect of heating to T = 45°C, which is greater than the gel to liquid crystal transition temperature of DPPC (Tc= 41 °C), is found to be particularly detrimental to the adsorption of 7:3 DPPC:PG. Of the phospholipid mixtures studied, extracted cow lung lipids exhibited by far the greatest adsorption capability and also showed less path dependence than 7:3 DPPC:PG. Similarly, in terms of dispersion techniques investigated, sonication on ice tended to give the most rapid adsorption for a given phospholipid mixture.SpeculationTreatment of neonatal Respiratory Distress Syndrome by exogenous surfactant replacement with well-defined mixtures of synthetic phospholipids is an attractive potential alternative to the use of multicomponent lung extracts. However, the existence of a variety of possible metastable solution states for phospholipid mixtures requires that adsorption properties be characterized for each mixture as a function of dispersion technique. It appears probable that synthetic phospholipid mixtures of identical composition and apparent bulk concentration might give variable therapeutic results for different dispersion methods.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryUsing specific and sensitive radioimmunoassays for nerve growth factor (NGF) and epidermal growth factor (EGF), we studied the developmental profile of NGF and EGF concentrations in male mouse submaxillary gland (SMG) from 2–60 days of age. We measured NGF concentrations in mouse cerebellum, cerebral cortex, and brain stem from ages 2–32 days. In addition, we assessed mouse serum thyroxine (T4) and triiodothyronine (T3) levels in seperate groups of animals ranging from 5–50 days of age. Mean SMG EGF content and concentration exceeded that of NGF between 2 and 18 days of age. At all subsequent ages, however, mean NGF and EGF content and concentration were similar. SMG NGF and EGF content were low at 2 days of age, decreased slightly through 8 days of age, and increased exponentially after 11 days of age with three phases of increase being apparent for both proteins. In the first phase, mean SMG NGF and EGF contents increased 2.4− and 2.3-fold respectively between 11 and 18 days of age. A second phase of increase was noted between 18 and 32 days when NGF and EGF increased 9845− and 7805-fold respectively. In phase three (32–60 days of age) more modest increases of 6.5-fold in mean NGF and EGF content were noted.Cerebellar NGF concentrations increased from 681 to 2241 pg/mg protein between ages 2 and 15 days and subsequently fell to a plateau level of 1304 pg/mg protein by age 18 days. Cerebral cortical NGF concentrations increased steadily from 251 to 1383 pg/mg protein between ages 2 and 32 days, whereas brain stem NGF concentrations maintained a plateau averaging 1100 pg/mg protein.Serum T4 concentrations in the mouse increased dramatically from 2.5 μg/dl at 5 days to a maximum of 8.1 μ/dl at 15 days, thereafter decreasing to a nadir 4.4 μ/dl by 40 days. Serum T3 concentrations followed a similar pattern, rising from 25 ng/dl on postnatal day 5 to 93 ng/dl on day 15, with a subsequent decline to 63 ng/dl by day 30. These results indicate a correlation between the increase in serum thyroid hormone levels in the mouse and the increases in SMG NGF and EGF levels and brain NGF levels between 5 and 32 days.SpeculationWe and others have demonstrated that thyroid hormones increase brain NGF concentrations and stimulate submaxillary gland NGF and EGF synthesis. The present results are compatible with the hypothesis that the early increase in circulating thyroid hormone concentrations in the mouse play an important role in the increase in cerebral and cerebellar NGF levels during the first 3 wk and the increase in SMG NGF and EGF concentrations between 11 and 32 days of age. The known increase in mouse serum testosterone to adult male levels between 4–12 wk of age may be a factor in the late increase in NGF and EGF elevations after 32 days of age.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryThe possible role of human neutrophils (PMN) as direct effector cells against free live virus particles was testedin vitro.Oxygen consumption, production of chemiluminescence and “virus killing” by PMNs was examined during and after incubation of cells and live or dead vaccinia virus with and without specific antibody. Oxygen consumption and chemiluminescence production occurred with unopsonized live but not with inactivated virus and was greatly enhanced with opsonization. Virus titers were determined in PMN-free supernatant and freeze-thawed cell pellet fractions after 15 min incubation. Reduction in titer from virus control was seen in supernatant fractions with and without opsonins, but in the cell fraction only with opsonins; the degree of reduction with opsonins was directly related to the opsonin source. PMNs from a patient with chronic granulomatous disease did not inhibit virus replication. These data suggest an active role for human PMNs in the genesis of and defense against virus infections and indicate areas for further investigation.SpeculationHuman neutrophils may play a role in the pathogenesis of and control of virus infections.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryPolyisoprenols of the dolichol class have been identified in urinary sediment for the first time and quantified by a high performance liquid chromatographic method. In the late infantile and juvenile forms of Neuronal Ceroid Lipofuscinosis (Batten disease), greatly increased amounts of dolichols of C-90 to C-105 were found in the urinary sediment compared with a variety of other neurologic disorders and age-matched normal subjects. Dolichols purified from the urinary sediment of a late infantile Batten disease patient were shown to have spectroscopic and chemical properties identical to standard preparations of liver and brain dolichols.SpeculationMeasurement of dolichols in the urinary sediment could be of value in diagnosis and screening of siblings of Batten disease. The discovery that dolichols are present in the storage cytosomes, are increased in both the brain and dehisced renal tubular cells in the urine suggests that the basic biochemical defect in these inherited disorders lies on pathways involved in the utilization of dolichols for glycoprotein synthesis.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryThe physiological basis for the defect in NaCl reabsorption in cystic fibrosis (CF) sweat glands is not known. We have systematically followed the concentrations of the three major inorganic electrolytes in sweat as a function of single gland sweat rate in patients with CF and normal individuals. The result demonstrates that (1) at low sweat rates, sweat glands of CF individuals can reduce NaCl concentrations to normal levels and (2) that the concentration of organic anions and/or HCO3in CF sweat is substantially less than in normal sweat.SpeculationPresent data and other findings suggest that Na/K transport and a postulated Na/H exchange are normal, but that a postulated anion exchange may be defective in cystic fibrosis sweat glands. These observations suggest an underlying transport genetic abnormality, which might explain observed abnormalities in cystic fibrosis exocrine gland secretions in general.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryTo study the developmental pattern of chemotactic factor in-activator (CFI) activity, although avoiding the effects of labor and delivery, serial blood samples were obtained from eight chronically catheterized lamb fetuses, 13 pregnant, and 13 nonpregnant ewes. The biologic profiles of adult sheep neutrophils in response to sheep C5-derived chemotactic fractions (C5-fr) were determined by the chemotactic and lysosomal enzyme release assays. CFI activity in sheep plasma was characterized and measured by the % inhibition of C5-fr-induced neutrophil lysosomal enzyme release.The chemotactic and enzyme release profiles of sheep neutrophils paralleled those of human neutrophils. Sheep plasma was shown to contain a CFI-like activity similar to that in human plasma.Mean CFI activity was higher in the plasma of pregnant ewes as compare to nonpregnant ewes (7.60versus5.15%,P< 0.001). Higher CFI levels (39.5%) were shown in the plasma of chronically catheterized fetuses early in the third trimester of pregnancy (109 days gestational age). These fetal levels decreased progressively to attain normal adult levels at fetal maturity (147 days gestational age) and no significant changes were noted at or after birth. Because identical changes occurred in all chronically catheterized fetuses, a developmental pattern was defined for CFI. Control CFI levels from six acutely catheterized fetuses did not differ from those predicted by the developmental pattern. Thus, the changes in CFI activity were not related to the chronic catheterization or to events surrounding labor and delivery; rather CFI levels correlated best with fetal immaturity.CFI levels correlated inversely with ability of zymosan activated plasma to induce neutrophil chemotaxis (r= —0.96,P< 0.01), suggesting that CFI plays a major role in the regulation of leukocytes chemotaxis.These data confirm previous findings in human neonates and provide a model for future studies. Further studies into the biology of the changes in CFI activity in the fetus and the influence of such high risk factors as prematurity, fetal distress or premature rupture of membranes should enhance our understanding of the immunocompromised neonate.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

SummaryThe respiratory activity in newborn preterm (29 days gestation) rabbits was studied after administration of thyrotropic releasing hormone. Intraperitoneal injection induced an increase in respiratory frequency (f) and a decrease in tidal volume (VT) resulting in a slight increase in pulmonary ventilation (&OV0312;E). These effects were seen in parallel to a decrease in expiratory time (TE) and respiratory time (TTOT). An increase in the TI/TTOTratio but (unaffected) VT/TIratio indicates that thyrotropic releasing hormone affects “respiratory timing” mechanisms rather than “inspiratory drive.” The changes in respiratory parameters are most probably due to an effect on the central respiratory controlling centers in the brain stem.SpeculationThe increased respiratory activity seen after administration of thyrotropic releasing hormone indicates that this tripeptide may have favourable effects in conditions accompanied by irregular or apnoic breathing during the perinatal period.

ISSN:0031-3998    

出版商:OVID    

年代:1982

数据来源: OVID