Search PubMed⌕ Search

Biomedical subjects

B Johnson

Publications and source records attributed to B Johnson.

At least 253 records · Page 14Linked to original sources
PubMed1989

Effects of chlorhexidine solution on neutrophil locomotion in vitro.

The aim of this study was to ascertain the effect of low concentrations of chlorhexidine on the locomotor behaviour of neutrophils. A special feature was the use of a direct test of chemotaxis. Neutrophils recovered from peripheral blood of healthy adult volunteers were tested for chemokinesis and chemotaxis in the presence of chlorhexidine. A moderate dose-related direct response was observed in respect of both these parameters. It was also apparent that increasing concentrations of the drug inhibited a greater proportion of cells, so that there was total immobility at 0.2 per cent and many cells appeared lysed.

Adult↗
PubMed1989

Intrapleural bupivacaine--technical considerations and intraoperative use.

The authors evaluated the incidence and type of technical problems associated with blind insertion of intrapleural catheters placed in 21 anesthetized patients and then injected in a double-blind fashion with 0.5% bupivacaine (1.5 mg/kg) or isotonic saline. The patients' chests were then opened, catheter positions located, and the lungs inspected. Eleven of the catheters were located with the tips intrapleurally, three extrapleurally, and seven actually in lung tissue. Eight patients had holes in the lung surface. Three patients had a pneumothorax, two of which were under tension. Plasma bupivacaine levels reached maximal concentrations at about 20 minutes in those with intrapleurally placed catheters, but not until 60 minutes when the catheter had actually penetrated the lung. Significant variations in plasma bupivacaine levels were achieved when the catheter entered lung tissue, with potentially toxic levels in one patient. To evaluate intraoperative analgesic effects, all patients were given a standard anesthetic with isoflurane, oxygen, and a muscle relaxant. There was no significant difference in isoflurane requirement between the groups who had bupivacaine v saline injected into their intrapleural catheters before surgery. It is concluded that blind insertion of intrapleural catheters can be hazardous, especially if followed by positive-pressure ventilation. In addition, catheter placement in lung tissue, which was not uncommon, delays the time for peak plasma concentrations and may increase risk of toxicity. Intrapleural bupivacaine was not found to be a useful adjunct to general anesthesia during thoracotomies.

Adult↗
PubMed1989

Lipid effects of celiprolol, a new cardioselective beta-blocker, versus propranolol.

The metabolic effects of celiprolol, a new beta-adrenoceptor blocking agent with intrinsic sympathomimetic activity and alpha 2-blocking properties, were evaluated in a series of patients with hypertension, both with and without hyperlipidemia. Propranolol was tested as the reference drug in a randomized double-blind trial. Of the 35 patients of both sexes who completed the study, 17 were hyperlipidemic (low-density lipoprotein cholesterol greater than or equal to 170 mg/dl) and 18 were normolipidemic. Both drugs exerted a similar hypotensive effect after gradual dose adjustment; however, propranolol reduced heart rate to a higher extent (-20.5%) than celiprolol (-7.7%). Propranolol determined a significant rise of total and very low-density lipoprotein (VLDL) associated triglyceridemia, whereas high-density lipoprotein cholesterol (HDL cholesterol) levels and the total cholesterol/HDL cholesterol ratios were significantly depressed, particularly in hyperlipidemic patients. Celiprolol, in contrast, slightly decreased triglyceridemia (significantly in the hyperlipidemic group at week 12) and caused a 5% increase of the HDL cholesterol levels. The total cholesterol/HDL cholesterol ratio was reduced by celiprolol at week 16 in both hyperlipidemic and normolipidemic patients. The effects of the two beta-adrenoceptor blockers on HDL cholesterol and triglyceride levels differed significantly after 12 and 16 weeks of treatment, which confirm the divergent metabolic effects of the two agents.

Adrenergic beta-Antagonists↗
PubMed1989

Epinephrine-induced premature ventricular contractions and changes in arterial blood pressure and heart rate during I-653, isoflurane, and halothane anesthesia in swine.

I653 is a new inhalation anesthetic having especially desirable recovery characteristics because of its very low blood and tissue solubility. Investigations of its cardiovascular and electroencephalographic effects have revealed actions similar to those of isoflurane. However, these studies did not evaluate the potential of I653 to predispose the heart to epinephrine-induced arrhythmias. In this investigation, we studied eight domestic swine to compare the effects of I653 with those of other anesthetics on the cardiac arrhythmogenic actions of intravenously infused epinephrine. I653, isoflurane, and halothane each were given, on separate days, at 0.7-0.8 and at 1.1-1.2 MAC. The rate of infusion of epinephrine needed to produce premature ventricular contractions (PVCs) when the animals were anesthetized with I653 (6.9 +/- 0.7 and 6.6 +/- 0.9 micrograms.kg-1.min-1 at 0.8 and 1.2 MAC) did not differ from that during isoflurane anesthesia (5.7 +/- 1.1 and 6.0 +/- 1.0 micrograms.kg-1.min-1 at 0.7 and 1.1 MAC), but was greater than that required during halothane anesthesia (1.3 +/- 0.2 and 1.1 +/- 0.3 micrograms.kg-1.min-1 at 0.7 and 1.1 MAC). Similar mean arterial blood pressures and heart rates resulted from like infusions of epinephrine during I653 and isoflurane anesthesia. PVCs occurred at lesser infusion rates of epinephrine and at lower mean arterial blood pressures and heart rates with halothane than with I653 or isoflurane. Anesthetic concentration, over the range studied, did not alter the infusion rate of epinephrine required to produce arrhythmias with any anesthetic. The authors conclude that I-653 and isoflurane have similar properties with respect to epinephrine-induced arrhythmias and increases in heart rate and arterial blood pressure.

Anesthetics↗
PubMed1989

The relationship between knowledge about acquired immunodeficiency syndrome and the implementation of universal precautions by registered nurses.

The relationship between the level of knowledge of registered nurses (RNs) concerning acquired immunodeficiency syndrome (AIDS)-related issues and the practical observance of universal precautions was studied. It was hypothesized that the more knowledge a nurse has concerning AIDS the more likely he or she is to implement universal precautions. All registered nurses who have direct patient contact (N = 400) and are employed at a Northeastern teaching medical center, were provided a packet of three questionnaires and encouraged to participate. Two hundred thirteen (53%) RNs returned completed questionnaires. Subgroups were examined for trends relating such parameters as age and the amount of AIDS knowledge, using analysis of variance. The major hypothesis was tested by correlating the overall scores for AIDS knowledge and the implementation score. Results indicated no relationship between knowledge and the implementation of universal precautions (r = -0.12). When evaluating scores according to work areas, those subjects with higher knowledge scores had lower practice scores. Other demographic variables showed no influence on either knowledge or implementation scores as measured by this study. Further study is needed to understand what factors will motivate RNs to implement universal precautions.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Adverse effects of the use of unusual phenethylamine compounds sold as illicit amphetamine.

A 40-year-old man, who had regularly taken illicit amphetamine by intra-nasal inhalation for several years without ill effects, was admitted to hospital with signs of massive adrenergic overstimulation shortly after inhaling material which he had purchased in the belief that it was amphetamine. The administration of the beta-blocker practolol produced a paradoxical increase in blood pressure. After his discharge from hospital he suffered disabling feelings of anxiety for several weeks. Analysis of a sample of the material showed it to contain p-methyl amphetamine and N, p-dimethyl amphetamine.

Adult↗
PubMed1989

Granulocyte-macrophage colony-stimulating factor may inhibit neutrophil migration in vivo.

Recombinant human granulocyte-macrophage colony-stimulating factor (rh GM-CSF) was administered by constant intravenous infusion to eight patients with malignant disease prior to chemotherapy. rh GM-CSF was given at a dose of 15 to 25 micrograms m-2 h-1 for 1 or 2 h. Neutrophil migration into an inflammatory zone was monitored throughout this period using a micropore skin window technique. Neutrophil migration into the micropore membrane prior to the commencement of the rh GM-CSF infusion was almost identical to that in eight normal control individuals (leading front distance of migrating neutrophils in 20-min period 81.3 +/- 7 microns in the patients compared to 79.4 +/- 4 microns in the control individuals). During the rh GM-CSF infusions there was a significant fall compared to controls in the number of neutrophils entering the membrane and the leading front distance (P less than 0.05). In four out of nine patient studies (eight patients) there was a greater than 30% fall from the pre-infusion level. In the control individuals the largest fall recorded was less than 10% and overall there was a progressive rise in the number of neutrophils entering the membrane throughout the period of study. This study suggests that intravenous infusion of rh GM-CSF may impair the ability of neutrophils to infiltrate an inflammatory focus.

Colony-Stimulating Factors↗
PubMed1988

Effects of a low saturated fat, low cholesterol fish oil supplement in hypertriglyceridemic patients. A placebo-controlled trial.

STUDY OBJECTIVE: To determine the effects of fish oil supplements low in saturated fat and cholesterol on plasma lipid and lipoprotein levels in hypertriglyceridemic patients. DESIGN: Single-blind, placebo-controlled (safflower oil), crossover trial with 6-week treatment periods. SETTING: Outpatient lipid clinic in a university medical center. PATIENTS: Eleven adult patients had isolated hypertriglyceridemia (type IV) and seven had concomitant hypercholesterolemia (Type IIb). INTERVENTION: Twelve 1-g capsules of either fish oil or placebo (safflower oil) were taken daily during each treatment period. MEASUREMENTS AND MAIN RESULTS: Blood was drawn at the fifth and sixth week of each period and analyzed for total lipids; cholesterol in very low, low (LDL), and high density (HDL) lipoproteins (mmol/L); and apoprotein B (mg/dL). Compared with the placebo, fish oil lowered plasma triglyceride levels (4.0 +/- 1.8 to 2.5 +/- 1.0), and raised LDL cholesterol levels (3.7 +/- 1.75 to 4.25 +/- 0.85), apolipoprotein B levels (122 +/- 29 to 140 +/- 34), and the ratio of LDL cholesterol to HDL cholesterol (4.0 +/- 0.9 to 4.7 +/- 1.4) (P less than 0.05; mean +/- SD). No significant changes were seen in levels of HDL or HDL cholesterol subfractions. Similar responses were seen in patients with both type IIb and IV lipoprotein phenotypes. CONCLUSIONS: Because the fish oil supplement contributed negligible amounts of cholesterol and saturated fat to the diet, the n-3 fatty acids most likely caused the observed effects. These findings indicate that relatively small amounts of fish oil can have beneficial effects on plasma triglyceride levels in hypertriglyceridemic patients, but the increase in LDL cholesterol and apoprotein B levels, and in the LDL cholesterol to HDL cholesterol ratio suggests the need for careful monitoring of plasma lipoprotein changes during fish oil supplementation, and for a careful evaluation of their long-term benefits.

Apolipoproteins B↗
PubMed1988

Comparative tumorigenicity of 1-nitropyrene, 1-nitrosopyrene, and 1-aminopyrene administered by gavage to Sprague-Dawley rats.

The carcinogenic activities of 1-nitropyrene, a mutagenic component of diesel exhaust, and its reduced derivatives 1-nitrosopyrene and 1-aminopyrene were evaluated in male and female Sprague-Dawley rats. Within 24 h of birth, groups of 22-36 rats were treated by gavage with trioctanoin or the appropriate compound in trioctanoin once weekly for 16 weeks. The approximate total doses per rat were as follows: 1-nitropyrene, high dose (800 mumol); 1-nitropyrene, low dose (320 mumol); 1-nitrosopyrene (320 mumol); 1-aminopyrene (320 mumol). The experiment was terminated after 94 weeks. The main site of tumor induction was the mammary glands of female rats. Percentages of incidences of mammary adenocarcinomas in female rats were as follows: 1-nitropyrene, high dose (63%); 1-nitropyrene, low dose (42%); 1-nitrosopyrene (19%); 1-aminopyrene (4%) trioctanoin (3%). These incidences were significantly greater than those of controls for the female rats treated with either 1-nitropyrene or 1-nitrosopyrene. Low and generally insignificant incidences of tumors of a variety of other sites were also observed in rats treated with 1-nitropyrene. The induction of mammary tumors by 1-nitropyrene confirms the results of a previous study (Hirose et al., Cancer Res., 44: 1158-1162, 1984). The present results also demonstrate that, under the conditions of this bioassay, 1-nitropyrene was significantly more carcinogenic than either 1-nitrosopyrene or 1-aminopyrene.

Adenocarcinoma↗
PubMed1988

Mechanisms of glucocorticoid function in human leukemic cells: analysis of receptor gene mutants of the activation-labile type using the covalent affinity ligand dexamethasone mesylate.

In the cultured acute lymphoblastic leukemic (ALL) cell line, clones of sensitive cells are killed by receptor-occupying concentrations of glucocorticoids. In addition, several types of resistance have been identified. The types of resistance are r- (glucocorticoid binding site loss), ract/l (activation labile receptors) and r+ly- (defective lysis mechanism). The two types of receptor mutants have been examined for the presence and expression of the glucocorticoid receptor (GR) gene. Southern blot analysis, using a full-length cDNA probe for human GR, shows that the gene in both is grossly intact. Examination of the expression of the gene by Northern blots reveals the presence of normal, 7-kb message in both types of receptor mutants, though in amounts somewhat reduced from wild-type. This report focuses on the activation labile mutants. Since characterization of these mutants suggests that they can bind ligand but not retain it during activation, we hypothesized that they would respond normally to a ligand that could not be lost during activation. This seems to be the case. When the covalent affinity ligand dexamethasone mesylate, itself a partial glucocorticoid agonist/antagonist, is used, the ract/l cells are killed to an extent corresponding to that evoked by a sub-optimal concentration of the full agonist dexamethasone. We conclude: (1) that the ract/l receptors can function to kill cells if provided a ligand that they do not lose during activation; (2) that the partial agonist activity of dexamethasone mesylate for cell killing is not due to release of a small amount of free dexamethasone; (3) that the poor agonist activity of dexamethasone mesylate receptor complexes suggests that the role of steroid is strictly to participate in conversion of the receptor to its DNA binding form, after which presence of the steroid actually interferes with proper receptor action.

Cell Division↗
PubMed1988

Dietary fat in relation to fatty acid composition of red cells and adipose tissue in colorectal cancer.

Fatty acids were determined in erthrocytes in 49 patients with colorectal cancer and compared with age and sex-matched controls. Marginally increased levels of stearic acid (P = 0.057) and oleic acid (P = 0.064) and decreased arachidonic acid (P = 0.043) occurred in cancer patients. There was no difference in the stearic to oleic acid ratio between the two groups. Dietary intake, assessed by dietary recall and adipose tissue analysis was also not different. In control subjects the polyunsaturated:saturated (P:S) fatty acid ratio correlated between diet and adipose tissue (P less than 0.01, at least). In contrast cancer patients showed different correlations; in particular dietary and erythrocyte P:S fatty acid ratios correlated (P less than 0.01). These findings may indicate disturbed fat metabolism in cancer patients. The erythrocyte stearic to oleic acid ratio is of no diagnostic value.

Adenocarcinoma↗
PubMed1988

Cockarde nevus: a case report and review of the literature.

Benign acquired melanocytic nevi usually display an even and uniform architecture and coloration easily recognized by the dermatologist. The cockarde nevus, a variant of the melanocytic nevus, is an exception. It displays a targetlike morphology with histologic characteristics of a compound nevus. We believe because the lesion has been rarely reported in the American literature, it is often mistaken in this country for a dysplastic nevus.

Child↗
PubMed1988

RNA complementary to herpes simplex virus type 1 ICP0 gene demonstrated in neurons of human trigeminal ganglia.

Recent studies with mice have demonstrated abundant RNA transcripts which are complementary (antisense) to the herpes alpha gene ICP0 in latently infected ganglia. We investigated the situation in unselected human trigeminal ganglia. Strand-specific 2.7-kilobase herpes simplex virus type 1 (HSV-1) ICP0 RNA probes were prepared, and their sense was determined in productively infected cells. Although in situ hybridization demonstrated ICP0 antisense RNA transcripts in the nuclei of neurons in 46% of the ganglia, ICP0 messenger RNA was not found in any of the ganglia. We conclude that HSV-1 antisense ICP0 RNA is present in humans during ganglionic latency.

Adult↗
PubMed1987

Modulation of platelet-activating-factor-induced calcium influx and intracellular calcium release in platelets by phorbol esters.

The mechanisms by which platelet-activating factor (PAF) and thrombin increase intracellular calcium were examined. Platelets were loaded with the calcium-sensitive fluorescent probe Quin 2 and then were suspended in buffer containing 0.5 mM-Mn2+ in order to quantify simultaneously calcium release from intracellular stores and divalent cation influx. Pretreating platelets with agents which activate protein kinase C [the phorbol ester phorbol myristate acetate (PMA) or the diacylglycerol 1-oleoyl-2-acetylglycerol (OAG)] inhibited increased intracellular calcium by PAF and thrombin in a dose-related manner. That protein kinase C regulates intracellular calcium by phosphorylating proteins in two distinct pathways was suggested by two observations. PAF-induced calcium release was more sensitive to inhibition by PMA and OAG than was manganese influx and the kinetics of recovery from inhibition were different for the two pathways. Both PMA and OAG aggregated Quin 2-loaded platelets without eliciting measurable increases in intracellular calcium. In contrast, prostacyclin, which increases intracellular cyclic AMP, inhibited calcium release and influx in parallel, suggesting that this agent acts at a step common to both pathways.

Blood Platelets↗
PubMed1987

Molecular analysis of the short arm of chromosome 3 in small-cell and non-small-cell carcinoma of the lung.

Previous studies have suggested that the loss of DNA sequences on the short arm of chromosome 3 (3p) is associated with small-cell lung carcinoma. We therefore looked for loss of 3p alleles in tumor tissue from 42 patients with either small-cell or non-small-cell lung carcinoma. All 13 patients with small-cell lung carcinoma who were heterozygous for one or more alleles at 3p in normal tissue had the loss of at least one codominant allele in the tumor tissue. Cell lines of small-cell lung carcinoma from an additional eight patients were homozygous for 3p alleles; this result was significantly different from the predicted frequency of homozygosity. The tumor tissue studied included cell lines of small-cell lung carcinoma obtained from biopsy specimens, an autopsy sample, and an excised lymph node containing tumor cells. Loss of alleles at 3p was observed in tumor samples obtained before and after chemotherapy. Four of 15 evaluable patients with non-small-cell carcinoma of the lung had loss of 3p alleles. We conclude that loss of alleles at 3p is a change found consistently in small-cell lung carcinoma and occasionally in non-small-cell lung carcinoma.

Alleles↗