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Biomedical subjects

D Dai

Publications and source records attributed to D Dai.

63 records · Page 4Linked to original sources
PubMed1991

[Consecutive study of nutritional composition of milk from mothers of preterm delivery].

The content of protein, fat, lactose, potassium, sodium, calcium, phosphorus, magnesium, copper, iron, zinc in preterm human milk was determined from the longitudinal samples during the first 8 weeks of lactation. Changes in content, over time were tested by analysis of variance. Protein, potassium, sodium, copper, iron, zinc content decreased significantly as lactation progressed. Based upon these data, a preterm infant fed 200 ml per kg per day of its own mother's milk would receive an excess of all substrates except calcium, phosphorus and iron over the estimated intrauterine accretion rates. Within 4 weeks the first in the postpartum period, the average intake of calcium, phosphorus, magnesium and copper was lower than the recommended intake. Iron intake is not adequate. After 4 weeks, the average intake of protein, sodium and zinc was lower than the recommended intake. The results may offer a basic datum for establishing premature infant feeding and formulation of human milk fortifiers (HMF).

Adult↗
PubMed1991

[Copper, iron and zinc content of preterm and term human milk and cow's milk].

Sixty-eight samples of preterm human milk and 39 samples of term human milk were obtained during 4 weeks postpartum from 7 mothers delivering prematurely and 9 mothers giving birth at term. Eleven cow's milk samples were obtained at random from 11 healthy cows. Samples were measured by flame method using an atomic absorption spectrophotometer (Type WYX-402). The three trace elements content of PT and FT milks decreased significantly with duration of lactation, and the content of each mineral was higher during the first week than that measured during the fourth week. PT and FT milk did not differ significantly in the content of the three elements during the first month of lactation. Copper content of PT milk at each week, iron content of PT milk at the first week and zinc content of PT milk during the first two weeks of lactation are higher than those of cow's milk respectively. The intake of copper, iron and zinc of the preterm infant fed his own mother's milk or cow's milk was calculated. Comparison of the intake level of copper and zinc of breastfed and cow's milk-fed preterm infant with the recommended intake level of the two minerals was made. The results show PT milk is superior to cow's milk for copper, iron and zinc; may be helpful for promoting breast feeding and feeding the preterm infant with supplemental trace elements.

Animals↗
PubMed1990

Two new mutant loci (smhB and lytD) in Escherichia coli which confer temperature-sensitive growth and lysis phenotypes.

A temperature-sensitive mutation in the murH gene of Escherichia coli confers a lysis phenotype at the restrictive temperature. An extragenic suppressor of murH apparently representing a new locus at 12.5 min on the linkage map and designated smhB is described. The smhB mutation by itself also conferred a temperature-sensitive lysis phenotype. A mutation in another new locus designated lytD which arose spontaneously in the smhB mutant was mapped close to smhB at 12.7 min on the linkage map. The lytD mutation by itself conferred a temperature-sensitive lysis phenotype indistinguishable from that of the murH mutant. Thus, the suppression of lysis in the smhB murH and the smhB lytD double mutants suggests a mechanism involving the reciprocal suppression of the two individual lysis-causing mutant alleles. The suppressor activity of smhB was apparently relatively specific in that smhB failed to prevent lysis induced by either mutational (murE or murF) or antibiotic-induced blocks in peptidoglycan synthesis. This suggests that murH, smhB, and lytD may be functionally related.

Alleles↗
PubMed1989

[Clinical analysis of 4 Chinese hemophiliacs with human immunodeficiency virus infection].

Human immunodeficiency virus (HIV-is) now considered the causative agent of acquired immunodeficiency syndrome(AIDS). A high risk of AIDS has been reported among patients with hemophilia who received lyophilized commercial factor VIII and IX concentrates of American origin. In a prevalence survey conducted from September to December 1985, HIV antibodies were found in all the 4 patients with hemophilia treated with the batch number W87307, 955 I.U. of American commercial factor VIII concentrate supplied by Armour pharmaceutical Company U.S.A. One of the seropositive patients developed AIDS-related complex (ARC) and died of cerebral hemorrhage. The other three sero-positive patients had abnormalities in cell mediated immunity; among them two developed left lumbosacral radiculopathy and hemorrhagic herpes zoster and one remains well so far.

AIDS-Related Complex↗
PubMed1989

Clinical analysis of four Chinese hemophiliacs with human immunodeficiency virus infection.

Human immunodeficiency virus (HIV) is now considered as the causative agent of acquired immunodeficiency syndrome (AIDS). A high risk of AIDS has been reported among patients with hemophilia who received lyophilized commercial factor VIII and IX concentrates of American origin. At a prevalent survey from September to December 1985, HIV antibodies were found in all four patients with hemophilia treated with the batch number W87307, 955 I.U. of American commercial factor VIII concentrate supplied by Armour Pharmaceutical Company, USA. One of the sero-positive patients developed AIDS-related complex (ARC) and died of cerebral hemorrhage. The other three sero-positive patients had abnormalities in cell-mediated immunity. Of them two developed left lumbosacral radiculopathy and hemorrhagic herpes zoster and one remained well so far.

AIDS-Related Complex↗
PubMed1988

murH, a new genetic locus in Escherichia coli involved in cell wall peptidoglycan biosynthesis.

A temperature-sensitive mutant of Escherichia coli defective in peptidoglycan synthesis was characterized. The incorporation of radiolabeled meso-diaminopimelate into peptidoglycan by the mutant was inhibited at the restrictive growth temperature, resulting in autolysis. The defective step appeared to be part of the terminal stage in peptidoglycan synthesis involving the incorporation of disaccharide peptide units into the wall peptidoglycan. The mutation was assigned to a new locus, designated murH, at 99.2 min on the E. coli linkage map.

Cell Wall↗
PubMedDate not supplied

Development and validation of a novel technique for murine first-pass radionuclide angiography with a fast multiwire camera and tantalum 178.

BACKGROUND: The use of genetically altered mice as a model system to study cardiovascular disease has created a need for accurate and quantitative assessment of murine ventricular function. To address this very challenging problem, we have developed a technique of murine first-pass radionuclide angiography using pinhole imaging and the short-lived isotope tantalum 178 (Ta-178) with a high-speed multiwire proportional camera (MPC). METHODS AND RESULTS. An MPC was fitted with a pinhole lens of 2-mm-diameter aperture positioned 15 cm from the camera face. The short-lived isotope Ta-178 (half-life 9.3 minutes) was generated from the tungsten 178 (W-178) (half-life 21.7 days)/Ta-178 generator and concentrated on site to an injection volume of 15 to 20 microL. Mice were imaged in the supine position with the chest wall 3 mm from the camera pinhole aperture, and images were acquired at 160 frames per second after a rapid bolus injection of Ta-178. In the absence of a true gold standard, the technology was validated with measurements in control mice and mice with surgically ligated left anterior descending arteries (LADs). In addition, the effects of pharmacologic intervention with verapamil and with dobutamine were observed. Finally, peak aortic velocity measurements obtained with this technology were compared with those obtained with echocardiographic Doppler ultrasonography, the only available quantitative comparator. There was a significant decrease in the mean left ventricular ejection fraction (LVEF) between normal mice (62% +/- 4.6% [mean +/- SEM], n = 12) and mice with experimentally induced myocardial infarction produced by surgical LAD ligation (22% +/- 2.0%, n = 41; P <.01). The LVEF decreased from 51% +/- 5.8% to 37% +/- 3.5% in a group of normal mice receiving verapamil (P <.05, n = 8) and increased from 34% +/- 2.2% to 43% +/- 2.3% in a group of LAD-ligated mice receiving dobutamine (P <.01, n = 48). Peak camera sensitivity during first pass was 25,000 cps/mCi injected. Intraobserver and interobserver variability of LVEF was studied, yielding r = 0.9639 and 0.9529 and SE of the estimate 2.6% and 3.1%, respectively. Reproducibility in serial studies was excellent (r = 0.92, SE of the estimate 5.18). CONCLUSIONS: This study demonstrates the development and use of a promising new method that uses the short-lived radioisotope Ta-178 and MPC for noninvasive quantification of murine ventricular function, that produces accurate and highly reproducible results, and that can be applied in multiple serial studies.

Animals↗
PubMedDate not supplied

Role of bacterial colonization in neonatal necrotizing enterocolitis and its prevention.

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in premature infants. A major component of the pathophysiology of NEC is the nature of the interaction of bacteria with the premature gut. Intestine microflora are important to the host in resistance to bacterial infections. Diet and environmental conditions can influence this ecosystem. A breast-fed full-term infant has a preferred intestine microbiota in which bifidobacteria predominate over the potentially harmful bacteria, whereas in formula-fed infants coliforms, enterococci and bacteroides predominate. The pattern of bacterial colonization in the premature neonate gut is quite different from that in the gut of the healthy full-term infant. Those infants requiring intensive care acquire intestinal organisms slowly, and the establishment of bifidobacterial flora is retarded. A delayed bacterial colonization of the gut with a limited number of bacterial species tends to be virulent. Bacterial overgrowth is one of major factors promoting bacterial translocation. The aberrant colonization of the premature infant may contribute to the development of NEC. Breast feeding protects infants against NEC. Oligosaccharides and glycoconjugates, natural components in human milk, may prevent intestinal attachment of enteropathogens by acting as receptor homologues. Probiotics and prebiotics modulate the composition of human intestine microflora to the benefit of the host. The beneficial effects may result in the suppression of colonization of harmful microoganisms and/or the stimulation of bifidobacterial growth. In the future, control and manipulation of bacterial colonization in the neonate gut may be a new approach to the prevention and treatment of bacterial intestinal disease of various etiologies.

Bacteria↗