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Biomedical subjects

D Armstrong

Publications and source records attributed to D Armstrong.

At least 541 records · Page 30Linked to original sources
PubMed1983

Serum arabinitol concentrations and arabinitol/creatinine ratios in invasive candidiasis.

Serum arabinitol concentrations and arabinitol/creatinine ratios were determined in 25 cancer patients with invasive candidiasis, 73 severely ill cancer patients who did not have invasive candidiasis, and 15 uninfected patients with chronic renal failure. Elevated arabinitol concentrations were found in patients with renal failure and invasive candidiasis. Serum arabinitol concentrations exceeded 1.19 micrograms/ml in 13 of 18 patients with invasive candidiasis who were studied when renal function was normal and in three of 52 control patients. Among patients with renal failure, 10 of 14 with invasive candidiasis but only four of 36 control patients had serum arabinitol concentrations of greater than 5.85 micrograms/ml. Serum arabinitol and creatinine concentrations were strongly correlated. The arabinitol/ creatinine ratio exceeded 1.5 in 16 of 25 patients with invasive candidiasis but in only three of 88 control patients. Increased serum arabinitol concentrations appear to reflect increased production of arabinitol by yeast in individuals with invasive candidiasis.

Candidiasis↗
PubMed1983

Comparative recovery of bacteria and yeasts from lysis-centrifugation and a conventional blood culture system.

Blood cultures obtained with a lysis-centrifugation (L-C) system and a conventional two-bottle broth system were compared for the recovery of bacteria and yeasts from 7,000 cultures. The L-C system recovered significantly more total organisms, Escherichia coli, and Candida spp. and detected more patients with bacteremia and fungemia due to members of the family Enterobacteriaceae and yeasts. The broth system recovered significantly more streptococci and detected significantly more low-level Pseudomonas bacteremias. Polymicrobic bacteremia and fungemia were detected equally well by either culture system. Aerobic organisms grew equally well on blood, chocolate, or brain heart infusion agar plates used for L-C inoculation. A total of 82% of colony counts measured no more than 10 CFU/ml of blood, and it was at these low levels that enhanced detection of organisms by either system was observed. The L-C system isolated organisms and detected yeasts more rapidly than did the broth system. Contaminants occurred in 8.2% of L-C cultures and 1.9% of broth cultures. Low colony counts on L-C plates occurred for both Staphylococcus epidermidis contamination and septicemia.

Bacteria↗
PubMed1983

Routine aerobic terminal subculturing of blood cultures in a cancer hospital.

Routine terminal aerobic subcultures of macroscopically negative blood culture bottles were evaluated during a 15-month period when 30,000 blood cultures were processed. Each blood culture set consisted of a vented and an unvented 50-ml broth bottle. Forty-eight pathogens and 47 contaminants were isolated only from terminal subcultures. Twenty-two of the significant isolates were yeasts (usually recovered from vented bottles), and 10 were Pseudomonas aeruginosa (usually recovered from unvented bottles). Blood cultures that were positive by terminal subculture provided clinically relevant information in many cases, whether other blood cultures were positive or not. Microbiology laboratories, particularly those in hospitals where yeasts and P. aeruginosa are commonly isolated from blood specimens, should evaluate carefully the need for terminal subcultures of blood culture bottles before abandoning their use.

Adult↗
PubMed1983

Nutritional survey of Bangladeshi children aged under 5 years in the London borough of Tower Hamlets.

The main deficiencies in the diet of Bangladeshi infants and children are vitamin D, iron, and later, calories. Protein intake is a little low in some, but in general is satisfactory. Calcium and vitamin C intakes are adequate. The proportions of food are often inappropriate, mainly because of a high carbohydrate intake. Weaning tends to be late, with predominant milk drinking, even into the second year of life. Convenience baby foods, containing mainly carbohydrate are the major components of the diet until well into the second and third years of life, without the conversion to family food seen in white children. Vitamin D is given to fewer than half the children. It may be given to fewer still if the observation that bottles were often unopened is true for many families.

Ascorbic Acid↗
PubMed1983

Choice of substrate in determining peroxidase activity in the amniotic fluid.

Peroxidase activity in the amniotic fluid has been measured with two different chromogens, O-dianisidine and p-phenylenediamine. No activity was demonstrable with the former substrate but was present with the latter. These results show that choice of substrate is important in determining peroxidase activity, especially in the amniotic fluid.

Amniotic Fluid↗
PubMed1983

Phase I evaluation of 2'-fluoro-5-iodo-1-beta-D-arabinofuranosylcytosine in immunosuppressed patients with herpesvirus infection.

2'-Fluoro-5-iodo-1-beta-D-arabinofuranosylcytosine (FIAC) is a potent selective inhibitor of the replication of herpes simplex virus types 1 and 2 (HSV-1, HSV-2), varicella zoster virus, and cytomegalovirus in cell culture systems. FIAC produces an unequivocal therapeutic effect in mice that have been inoculated with a lethal burden of HSV-1. We have administered FIAC to 32 host compromised patients, 30 with advanced cancer, who were experiencing acute herpesvirus infections (varicella zoster, 29; HSV-1, 2; HSV-2, 1); the drug was given by 20 min i.v. infusion twice a day for 7 days. The dosage levels explored were 60, 120, 240, 400, and 600 mg/sq m/day. Drug-induced myelosuppression became evident at 600 mg/sq m/day; thrombocytopenia exceeded leukopenia. The toxic low dose was 400 mg/sq m/day with mild nausea and rare myelosuppression. All 24 varicella zoster patients with cutaneous disease receiving FIAC, greater than or equal to 120 mg/sq m/day, experienced stabilization of cutaneous lesions within 48 to 72 hr; healing began promptly thereafter.

Antiviral Agents↗
PubMed1983

Aspergillosis of the cerebral ventricles in a heroin abuser. Case report and review of the literature.

Aspergillosis of the cerebral ventricles developed in a 36-year-old heroin abuser who died during the sixth week of illness. The diagnosis was not made during life. A review of our case and of four previous cases from the literature indicates that aspergillosis should be considered in parenteral drug abusers with the syndrome of chronic meningitis or ventriculitis. The diagnosis is difficult to establish, but serologic tests may be helpful. This form of CNS aspergillosis can be cured with antifungal drugs.

Adult↗
PubMed1983

Chronic pneumonitis caused by Hemophilus influenzae in an adult.

Chronic pneumonitis due to Hemophilus influenzae developed in a 68-year-old woman. The unusual aspects of this manifestation and the patient's chest roentgenographic findings are discussed. Hemophilus influenzae was isolated from lung tissue obtained at an open lung biopsy. The isolate was sensitive to ampicillin sodium, and therapy resulted in clinical and roentgenographic resolution of the infection.

Aged↗
PubMed1983

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis. IV. Changes in the electroretinogram and the standing potential of the eye.

The present study correlates ultrastructural abnormalities in the retinal pigment epithelium (RPE) with electrophysiologic changes demonstrated in examinations of dogs with canine ceroid-lipofuscinosis (CCL) at various stages of clinical involvement using dc electroretinograms (ERG), including the c-wave, as well as recordings of the variations of the standing potential (SP) of the eye, both of which reflect the activity of the pigment epithelium. Normal c-waves and SP variations were seen at early stages of disease. At later stages, specific signs of pigment epithelial impairment were found in the form of (1) markedly reduced SP variations, (2) an increase in amplitude of the trough after the b-wave, and (3) a disappearance of the c-wave, which was replaced by a negative potential. These ERG changes correlate very well with a damaged pigment epithelium that generates the positive potential of the c-wave, as well as with normal Müller cells that generates the negative potential coinciding in time with the c-wave, and contributing to the trough after the b-wave. In the end-stage of the disease all potentials of the ERG were reduced drastically, evidently as a sign of cessation of neuroretinal function. Similarities between English setters with CCL and human Batten disease are discussed.

Animals↗
PubMed1982

Studies on experimentally induced retinal degeneration. 1. Effect of lipid peroxides on electroretinographic activity in the albino rabbit.

Lipid hydroperoxides (LHP) have been synthesized and purified from linoleic, linolenic, arachidonic and docosahexaenoic acids, using soybean lipoxygenase and oxygen. Intravitreal injections into the eyes of mature, albino rabbits produced an early and then progressive decrease in the amplitude of a-, b- and c-waves of the ERG. Depending upon the amount and activity of the LHP preparation, ERG's were markedly decreased in amplitude (greater than 50%) within 4 days following the injection and by 12 days, the activity from peroxide treated eyes was essentially nonrecordable. In preliminary studies, these effects were less pronounced in adult pigmented rabbits of similar age, however, a younger pigmented rabbit was only slightly less susceptible to damage than the albino animals. In other experiments, peroxidized native phospholipids, malonaldehyde, hydrogen peroxide and sodium iodate were also shown to be cytotoxic, but not all were as toxic as the LHP. In contrast, retinol, vitamin A acetate and retinoic acid had no effect upon ERG activity, nor did the parent fatty-acid compounds or the borate buffer in which they were injected. These studies confirm previous reports where indirect production of lipid peroxides caused retinal degeneration. The present report extends these observations to demonstrate that when the retina and RPE are exposed to a sample of purified LHP, retinal function is altered in an irreversible way. We also demonstrate that a metabolic by-product (malonaldehyde) is likewise cytotoxic. However, the mechanisms by which the parent LHP and/or metabolites might act could be quite different. This new animal model should prove useful in evaluating further the ultrastructural changes which are observed during peroxidative damage of the retina in vivo, as well as in evaluating the therapeutic approaches to these problems of retinal degeneration.

Animals↗
PubMed1982

Increased arabinitol levels in experimental candidiasis in rats: arabinitol appearance rates, arabinitol/creatinine ratios, and severity of infection.

Renal colony counts, total arabinitol appearance, and the arabinitol/creatinine ratios in the serum and urine of rats with lethal candidiasis were measured. Total arabinitol appearance and the arabinitol/creatinine ratios increased significantly after infection. The serum arabinitol/creatinine ratio was high (2 SD above the mean value in normal animals) in five of six infected rats at 24 hr, in eight of eight at 48 hr, and in none of the control animals. The urinary arabinitol/creatinine ratio was high in 14 of 19 infected rats by 24 hr, in 11 of 11 by 48 hr, and in none of the control animals. Total arabinitol appearance and the arabinitol/creatinine ratios were highly correlated with renal colony counts. Arabinitol production in vitro was sufficient to account for the increased arabinitol appearance observed in vivo in 12 of 14 rats. Thus it is concluded that the excess arabinitol that appeared in vivo was produced by the infecting fungus and that arabinitol is a quantitative marker substance for candidiasis.

Animals↗
PubMed1982

The arabinitol appearance rate in laboratory animals and humans: estimation from the arabinitol/creatine ratio and relevance to the diagnosis of candidiasis.

The effects of renal function on serum concentrations of the candidal metabolite arabinitol were studied by examining the accumulation and elimination of arabinitol in animals and humans. Serum concentrations of arabinitol rose sharply and in direct proportion to creatine concentrations after nephrectomy in rats. The serum half-life of exogenous arabinitol was 20.8 hr in anephric rats but only 0.62 hr in sham-nephrectomized control animals. The mean +/- SD apparent space of distribution of arabinitol was 419 +/- 26 ml/kg. The fraction of exogenously administered arabinitol recovered in the urine was 0.73 +/- 0.13 in uremic rats, 0.85 +/- 0.28 in control rats, and 0.95 +/- 0.10 in normal dogs. The arabinitol/creatinine clearance ratio was 0.99 +/- 0.08 in normal dogs and 0.99 +/- 0.25 in 22 critically ill patients with cancer. Thus arabinitol is eliminated by nearly quantitative urinary excretion and its cleared at virtually the same rate as creatinine. Therefore, the rate of arabinitol appearance in the body from any source equals the urinary arabinitol excretion rate and is directly proportional to the concentration ratio of arabinitol to creatinine in serum or urine.

Animals↗
PubMed1982

Monolayered explants in the study of retinal pigment epithelial behavior in culture.

A technique that permits removal of viable retinal pigment epithelial (RPE) explants of determined size from Bruch's membrane, and the transfer of such explants with maintained apico-basal polarity to cell culture dishes is presented. The RPE is a polarized tissue where the apical surface is involved in the interchange of material between the choroid and sensory retina and in phagocytosis of visual receptor outer segments. The maintenance of this polarity is of importance in studies aimed at elucidating these functions on pure RPE explants in early primary culture. No previous work has presented a method that permits this maintenance. The possibility of standardizing the size of these explants should facilitate quantitative studies on phagocytosis and uptake of markers and labelled compounds. The described dissection procedure is also currently used to separate the RPE as a pure cell population from surgically removed chorio-retinal biopsies for cell culture purpose.

Animals↗