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Biomedical subjects

D Lee

Publications and source records attributed to D Lee.

At least 523 records · Page 29Linked to original sources
PubMed1987

A developmental study on types and frequency distribution of short apneas (3 to 15 seconds) in term and preterm infants.

We measured the frequency distribution and the ventilatory correlates of the various types of apneas 3 to 15 s long during sleep in eight term infants (birth weight 3.65 +/- 0.16 kg; gestational age 39.5 +/- 0.3 wk) and eight preterm infants (birth weight 2.07 +/- 0.18 kg; gestational age 34.3 +/- 0.4 wk). Each infant was studied on five to seven occasions from birth to 56 wk of postconceptual age using a modified flow-through system. Sixty-six paired epochs of quiet sleep (1163 min) and rapid eye movement sleep (829 min) were analyzed in term infants and 85 paired epochs of quiet sleep (1553 min) and rapid eye movement sleep (1328 min) in preterm infants. Of the 783 apneas recorded in term infants 82% were central, 1.5% obstructive, 0.5% mixed, and 16% were of the breath-holding type; the corresponding figures for the 4086 apneas recorded in preterm infants were 93, 0.5, 1.0, and 5.5%. This distribution was similar in the two sleep states but term infants had a higher percentage of breath-holding apneas than preterm infants (p less than 0.01). In preterm infants the rate of central apneas decreased with postnatal age (p less than 0.01); in term infants the rate did not change significantly. The duration of apneas showed a modal distribution for central apneas at about 8 s for both groups during the 1st month of life (p less than 0.05). The findings suggest: 1) apneas in the newborn and early infancy are primarily central and are more frequent in preterm than in term infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Apnea↗
PubMed1987

Liquid-chromatographic measurement of catecholamines and metabolites in plasma and urine.

In this general method for measuring the concentrations of neurotransmitters in body fluids by "high performance" liquid chromatography (HPLC), the procedures for extracting different biogenic amines from body fluids vary, but the basic chromatographic conditions are the same for all. We use citric/formic acid buffer as the mobile phase, a C18 column, and an electrochemical detector. Specificity is better than in previously reported methods. Because of its excellent cost efficiency, we consider this to be the method of choice for quantifying biogenic amines.

Antihypertensive Agents↗
PubMed1986

An analysis of the funding to, and by, the Medical Research Council of New Zealand during the period 1973-84.

Correcting for inflation, the government grant to the MRC from 1973-84 was maintained at 90% of that for 1973. Funding of units was constant at 12% of total disbursements. That for project grants decreased from 89% in 1973 to a low of 48% in 1981. Programme grants increased from 21% in 1974 to a peak of 40% in 1981. After 1981 there was a slight shift favouring project grants. Purchasing power of project grants fell to a low, in 1980, of 41.5% of that in 1974 but, from 1981-84 remained at 45%. The purchasing power of programme grants was protected and held at 90% of that in 1974. From 1982-84 expenditure on project grants running for 3 years decreased from 50-60%, to only 15% and, with the declining fraction of the budget allotted to project grants, and in their purchasing power, this may account for the perception of a shortage of funds for medical research. Sustained support for research in the main centres has changed little and reflects the number of full-time academic staff at each school.

Financing, Government↗
PubMed1986

The role of the nucleus raphe pontis and the caudate nucleus in alfentanil rigidity in the rat.

Attempts to eliminate or reduce the rigidity induced with high-dose narcotic anesthesia in the operating room have been only partially successful. Previous investigations of opioid receptor sites mediating this rigidity have implicated two central regions: the nucleus raphe pontis (NRP) within the reticular formation and the caudate nucleus (CN) within the basal ganglia. The present study used systemically administered alfentanil (ALF), a potent, short-acting fentanyl analog, and intracerebrally infused methylnaloxonium (MN), a quaternary derivative of naloxone, to elucidate further the functional role of the NRP and CN in rigidity. ALF (0.5 mg/kg s.c.) produced a reliable model of rigidity, as documented by gastrocnemius electromyography. The onset of this rigidity was within 60 s of ALF administration, with a total duration of approximately 40-50 min. Intracerebroventricular (i.c.v.) injections of 2.0 or 4.0 micrograms of MN 15 min prior to ALF treatment prevented rigidity, while 0.125 or 0.5 microgram had no significant effect on rigidity. MN injected directly into the NRP at doses as low as 0.125 microgram significantly antagonized ALF-induced rigidity, while injections of MN into the caudate nucleus at doses as high as 4.0 micrograms failed to antagonize ALF-induced rigidity. These observations demonstrate that injection of MN into the NRP is at least 16-fold more effective in blocking ALF-induced rigidity than MN injected into the ventricle and, more importantly, at least 32-fold more effective than MN injected into the CN. The results suggest that the NRP may be an important site for the neural control of muscular rigidity associated with high-dose narcotic administration.

Alfentanil↗
PubMed1986

Intracellular survival of Candida albicans in peritoneal macrophages from chronic peritoneal dialysis patients.

Candidal peritonitis is a tenacious infection in patients undergoing chronic peritoneal dialysis. Since little is known about host defenses of the human peritoneal cavity against fungi, we investigated the interaction of peritoneal macrophages (PM phi) from uninfected dialysis patients with Candida albicans blastospores. Chemiluminescence (CL) techniques were used to assess the respiratory burst activity of these cells, and candidacidal activity was evaluated with a fluorochrome microassay. In sharp contrast to peripheral blood polymorphonuclear leukocytes (PMNs) from healthy donors, which gave a brisk luminol-enhanced CL response to opsonized blastospores and killed 35% of cell-associated organisms, PM phi produced barely detectable luminol-enhanced CL and killed only 13% of intracellular Candida. These findings appeared to be associated with a decreased level of myeloperoxidase in PM phi. The mechanism of intracellular survival of C albicans also appeared to be related to relatively poor triggering of superoxide production during phagocytosis of viable blastospores. The CL response of PMNs to C albicans was opsonin-dependent, and peritoneal dialysis effluent was devoid of opsonic activity. These studies suggest that local cellular and humoral mechanisms of defense are inadequate for protection of peritoneal dialysis patients against candidal peritonitis.

Acridine Orange↗
PubMed1986

Troponoids. 7. Chemistry and dopamine agonist activity of ciladopa and related aralkyltroponylpiperazines.

A series of N-aralkyltroponylpiperazine derivatives were synthesized and evaluated for dopaminergic activity in rats rendered hypokinetic by the bilateral injection of 6-hydroxydopamine (6-OHDA) into the anterolateral hypothalamus. Several members of the series were active, and a structure-activity relationship is presented. A few selected compounds were also evaluated with regard to their ability to induce contralateral rotational behavior in rats with a unilateral 6-OHDA-induced lesion of the nigrostriatal dopamine (DA) pathway and to suppress elevated serum prolactin levels. The compounds were compared to bromocriptine. Some of the more potent analogues were also assayed for their binding affinity to dopamine (DA) and alpha 1-adrenergic receptors. The results established that the potency of some of the compounds were comparable or superior to that of bromocriptine indicated that potent dopaminergic activity was dependent on the presence of both a substituted phenyl and a troponylpiperazine moiety, and confirmed that the dopaminergic activity depends on relative and absolute stereochemistry.

Animals↗
PubMed1986

Efficacy of ciprofloxacin in experimental aortic valve endocarditis caused by a multiply beta-lactam-resistant variant of Pseudomonas aeruginosa stably derepressed for beta-lactamase production.

The emergence of multi-beta-lactam resistance is a limiting factor in treating invasive Pseudomonas infections with newer cephalosporins. The in vivo efficacy of ciprofloxacin, a new carboxy-quinolone, was evaluated in experimental aortic valve endocarditis caused by a strain of Pseudomonas aeruginosa which is stably derepressed for beta-lactamase production and is resistant to ceftazidime and multiple other beta-lactam agents. A total of 51 catheterized rabbits with aortic catheters in place were infected with this strain and then received no therapy (controls), ceftazidime (75 mg/kg per day), or ciprofloxacin (80 mg/kg per day). Ciprofloxacin sterilized all blood cultures and significantly lowered vegetation densities of P. aeruginosa by day 2 of treatment versus controls (P less than 0.0005) and animals receiving ceftazidime (P less than 0.0005). This beneficial effect of ciprofloxacin was also noted on therapy days 6 and 11. Ciprofloxacin rendered most vegetations (85%) culture negative over the 11-day treatment period and achieved bacteriologic cure in 73% of animals (P less than 0.0005 versus other therapy groups). Ciprofloxacin prevented bacteriologic relapse at 6 days posttherapy. No ciprofloxacin resistance was detected among Pseudomonas isolates from cardiac vegetations. Ciprofloxacin warrants further evaluation in vivo versus multi-drug-resistant gram-negative bacillary infections.

Animals↗
PubMed1986

Measurement of specific IgG antibody levels in serum of patients on regimes comprising high total dose beta-lactam therapy.

Sera from 125 patients receiving mean total doses of beta-lactam therapy of 215 g over a mean of 14 days were assayed by radioimmunoassay. Titres of anti-penicilloyl antibodies, expressed in arbitrary units of specific IgG per microliter of serum (u/microliter), ranged from undetectable (less than 3 u/microliter) to 1,650 u/microliter. There was a higher prevalence of elevated IgG levels in patients who developed haemolytic anaemia or neutropenia compared with patients with no adverse reactions but only in those patients who developed haemolytic anaemia were the antibody titres significantly higher. A subsidiary finding was that a correlation was established between mean total dose and prevalence of positive IgG titres, on a patient group basis (r = 0.87).

Anemia, Hemolytic↗