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Biomedical subjects

J D Johnson

Publications and source records attributed to J D Johnson.

At least 271 records · Page 15Linked to original sources
PubMed1982

Interaction of discoidal complexes of dimyristoyl phosphatidylcholine-cholesterol-apolipoprotein A-I with human plasma high density lipoprotein HDL3.

The interaction of human plasma high density lipoproteins (HDL3) with discoidal complexes of apolipoprotein A-I (apo A-I) and dimyristoyl phosphatidylcholine (DMPC) containing 0, 10, 20 or 30 mol % cholesterol was investigated. Discoidal complexes containing various amounts of cholesterol were prepared by incubating apo A-I and DMPC-cholesterol liposomes for 12 hr at 25 C; the protein-lipid complexes were isolated by gel filtration chromatography on Bio-Gel A15m. Increasing the cholesterol content from 0 to 30 mol % caused a decrease in the fluidity of the discoidal complexes as determined by fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene; a reduced phase-transition amplitude; a decrease in the ratio of apo A-I to DMPC; and an increase in the width of the discoidal complexes as determined by electron microscopy after negative staining. Incubation of the apo A-I-lipid complexes with HDL3 resulted in a complete breakdown of the discoidal structures and a transfer to DMPC and cholesterol to HDL3. As a result of lipid transfer, there was an increase in the size of HDL3. These in vitro results may be of significance as they relate to the interconversion of HDL subfractions during lipoprotein-lipase-induced lipolysis of triglyceride-rich lipoproteins.

Apolipoprotein A-I↗
PubMed1982

In vitro catabolism of human plasma very low density lipoproteins. Effects of VLDL concentration on the interconversion of high density lipoprotein subfractions.

The effect of lipolysis of human plasma very low density lipoproteins (VLDL) on the distribution of high density lipoprotein subfractions was studied in an in vitro system consisting of purified bovine milk lipoprotein lipase and albumin. The distribution of lipids and apoproteins (apoC-II and apoC-III) within the lipoprotein fractions corresponding to HDL2 (d = 1.063-1.120 g/ml) and HDL3 (d = 1.120-1.210 g/ml) was dependent upon the concentration of VLDL in the incubation mixture. After lipolysis of an incubation mixture containing VLDL-triglyceride (0.6 mg triglyceride/ml) and HDL3 (0.1 mg protein/ml), most of the lipid and apoproteins were recovered in HDL3. At higher concentrations of VLDL-triglyceride relative to HDL3-protein (1.8 or 2.4 mg of VLDL-triglyceride and 0.1 mg of HDL3-protein) the amount of lipid and apoprotein isolated in the HDL3 density fraction decreased after lipolysis and there was an increase in the amount isolated between d 1.063-1.120 g/ml. These results provide additional evidence for the conversion of HDL3 to HDL2 during lipolysis. Furthermore, they suggest that the relative distribution of plasma HDL2 and HDL3 is related to the rate of catabolism of triglyceride-rich lipoproteins.

Animals↗
PubMed1982

The prosthodontic management of cleft palate patients.

The role of the prosthodontist in the multidisciplinary approach to the treatment of the cleft palate patient has been described. A brief review of the literature on the historical background, epidemiology, and pathogenesis of the cleft palatal defect has been presented. A technique for constructing a cleft palate prosthesis has been outlined in detail. Treatment of several patients using this technique has produced excellent results. Prosthetic therapy aids the patient in developing normal speech, promoting deglutition and mastication and in closing off the oral cavity from the nasal cavity. The esthetic benefits can be instrumental in the psychologic and social acceptance of the cleft palate patient.

Adult↗
PubMed1982

A sensitive analytical apparatus for measuring hydrogen production rates. II. Application to studies in human infants.

We estimated hydrogen (H2) production by determining simultaneously the end-tidal concentration (ETH2) and the direct pulmonary excretion rate (VeH2) in normal-sized, healthy, term and preterm neonates between 2 days and 7 weeks of life who were receiving all their calories enterally as breast milk or a proprietary formula. We found that there was no peak or pattern in H2 production during the first 3 postprandial hours (mean VeH2 = 1.00 +/- 0.97 SD ml/kg/h; mean ETH2 = 40.3 +/- 33.1 SD ppm). Frequently, there was marked short-term variability of the ETH2 in a given infant (coefficient of variation = 13.4% +/- 18.7%). H2 production was elevated in normal neonates without signs of malabsorption. We found that VeH2 correlated with ETH2 using both nasopharyngeal catheter (r = 0.63; p less than 0.001) and nasal prong (r = 0.71; p less than 0.001) collection techniques. We conclude that breath hydrogen determinations in neonates are not readily comparable to similar studies in older patients. Longitudinal studies of individual infants may reveal changes in breath H2 excretion of sufficient magnitude to be distinguishable from moment-to-moment variations, and correlatable with certain intercurrent clinical problems affecting intestinal H2 production or pulmonary H2 excretion. However, interpretation of breath H2 determinations in human infants will be difficult.

Breath Tests↗
PubMed1982

Efficacy of safety of concurrent use of intranasal flunisolide and oral beclomethasone aerosols in treatment of asthmatics with rhinitis.

Steroid-dependent, chronic asthmatic patients with severe rhinitis or nasal polyps are often candidates for treatment with intranasal topical corticosteroids, such as flunisolide. The possibility of additive adrenal suppression, when flunisolide, beclomethasone and prednisone are given together, has not previously been studied. The need to asses the risk is suggested by reports of additive adrenal suppression when aerosol and oral steroids are used together to treat asthma, and by the demonstrably higher systemic availability of aerosol steroid given intranasally rather than via the lung. We performed a double-blind, placebo-controlled crossover assessment of the efficacy and safety of 3 weeks of intranasal flunisolide spray treatment (300 micrograms/day) in nineteen steroid-dependent chronic asthmatic subjects, who also had nasal polyps or severe rhinitis. During the study, their doses of prednisone and beclomethasone, used for asthma, were held stable. Morning serum cortisol levels and 24-hr urinary-free cortisol excretion were essentially the same after the placebo, and the flunisolide treatments. The intranasal flunisolide improved their nasal symptoms significantly (P less than 0.05). Local complications were negligible. Given conventional steroid doses like those used in this study, there appears to be no important risk to endogenous adrenal function from combining the use of intranasal, flunisolide spray with administration of other steroids by other routes, when this is deemed clinically necessary. If higher doses are used, the possibility of some additive adrenal suppressive effect cannot be excluded.

Administration, Intranasal↗
PubMed1982

Treatment of seasonal and perennial rhinitis with intranasal flunisolide.

Flunisolide (F), a potent fluorinated corticosteroid or its propylene/polyethylene glycol vehicle (V) were intranasally administered to 50 patients with ragweed hayfever and 75 patients with perennial rhinitis. Each patient was randomly assigned in a double-blind manner an indistinguishable metered pump spray device containing either F or V. Each hayfever patient administered two puffs in each nostril b.i.d. Each perennial rhinitis patient administered two puffs in each nostril t.i.d. Each puff of F contained 25 micrograms F. Hayfever and perennial rhinitis patients inhaling F demonstrated significantly lowered symptom scores compared to their V controls. Skin test positive patients with perennial rhinitis inhaling F demonstrated significantly large reductions in symptom scores and significantly greater subjective control of symptoms compared to their V control than their skin test negative counterparts inhaling F and V. Morning plasma cortisol measured prior to and at the end of 1 month and 3 months of F revealed no significant diminution in cortisol level compared to patients inhaling V. No long-term adverse local or systemic steroid effects attributable to F were observed. Flunisolide spray is a safe and effective modality for the treatment of seasonal and perennial rhinitis.

Administration, Intranasal↗
PubMed1982

Reaction products of aquatic humic substances with chlorine.

A major concern of the chlorination of aquatic humic materials is the ubiquitous production of trihalomethanes. A large number of other chlorinated organic compounds, however, have been shown to be formed by chlorine's reaction with humic substances. In this study, humic material was concentrated from a coastal North Carolina lake and chlorinated at a chlorine to carbon mole ratio of 1.5 at pH 12. A high pH was necessary for complete dissolution of the humic material and for production of adequate quantities of oxidation and chlorination products for extraction, separation and mass spectrometric identification. After concentration in ether, samples were methylated, separated with a 50-m OV-17 glass capillary column or a 25 m SP-2100 fused-silica column and identified. A Hewlett-Packard 5710A gas chromatograph interfaced to a VG Micromass 7070F double-focusing mass spectrometer was used. Low resolution, accurate mass measurements were made with a combined EI-Cl source. The ability to do low resolution, accurate mass measurements made possible a rapid scan function necessary for capillary column gas chromatography. Accurate mass measurements allowed increased confidence in the identification of compounds, most of which are not available as standards. The products identified in these studies were chlorinated aliphatic straight-chain acids dominated by di- and trichloroacetic acid and the chlorinated dicarboxylic acids: succinic, fumaric and maleic acids. Chlorinated and unchlorinated aliphatic mono- and dicarboxylic acids and unchlorinated polycarboxylic aromatic acids comprise the remaining bulk of the compounds identified.

Chemical Phenomena↗
PubMed1982

Favorable results of neonatal intensive care for very low-birth-weight infants.

From 1961 to 1976, 229 infants with birth weights ranging from 751 to 1,000 gm were admitted to the Stanford University Hospital Intensive Care Nursery. The overall neonatal mortality for these infants was 63% (144/229), and there were ten late deaths. Before 1967, no infant in this group who required mechanical ventilation survived; thereafter, 30% (34/114) of the ventilated patients survived. Of the 75 long-term survivors 60 participated in a high-risk infant follow-up program; these included 23 infants who had received mechanical ventilation. The mean birth weight of these infants was 928 +/- 67 (SD) gm. Seventeen children (28%) had significant morbidity: seven (12%) with severe handicaps and ten (17%) with moderate handicaps. During this same period, seven infants weighing less than 750 gm at birth were also observed. The three infants who had not required ventilatory support thrived; the other four infants had required respirators and were significantly handicapped. More recently, neonatal mortality for infants with birth weights from 751 to 1,000 gm has improved: for 1977 to 1980, it was 28% (33/118). Furthermore, neonatal mortality for ventilated infants in this weight group was 27% (26/95). These data indicate an improved prognosis for very low-birth-weight infants, even with ventilatory support.

California↗
PubMed1981

Fluorescence studies of the interaction of calmodulin with myosin light chain kinase.

The interaction of calmodulin with myosin light chain kinase produces an approximately 30% increase in myosin light chain kinase tryptophan fluorescence. This represents the first report of calmodulin-induced structural changes in a protein which it activates. We fund that the calmodulin-myosin light chain kinase interaction is: 1) dependent on [Ca2+] (half-maximal binding at pCa 6.2) and essentially independent of [Mg2+], 2) occurs before saturation of all four reported Ca2+-specific sites on calmodulin. 3) saturates with 1 mol of calmodulin bound per mol of kinase with an apparent affinity of approximately 2.0 X 10(7) M-1, 4) is specific for calmodulin over troponin-C, 5) is directly related to the activation of myosin light chain kinase for phosphorylation of myosin light chain. Fluorescence stopped flow studies of these calmodulin-induced fluorescence changes in myosin light chain kinase indicate that Ca2+ binding to calmodulin occurs very rapidly and is not rate-limiting while the calmodulin-induced fluorescence increase in myosin light chain kinase occurs as a biphasic process with rates of approximately 65 s-1 and 6 s-1. The fluorescence increase produced by calmodulin binding to myosin light chain kinase is completely reversed by ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid at a rate of approximately 2 s-1.

Animals↗
PubMed1981

Alterations in integrity of goldfish membrane induced by edetate disodium.

The effect of the chelating agent edetate disodium on the integrity of the goldfish membrane was examined. The time to produce death in goldfish exposed to secobarbital sodium was used as a reflection of membrane integrity. Although a minimum edetate disodium concentration was necessary to induce alterations in integrity, no direct relationship between the effect and concentration of the chelating agent was evident. The chelating agent's effect appeared to be an enhancement of the transport of the ionized drug form. The change in membrane integrity existed at least 24 hr after theoretical exposure to edetate disodium, but cyclic alterations in integrity could not be ruled out. The effect on integrity was also demonstrated to be nonpermanent, and the apparent loss in integrity was partially restored by calcium byt not by magnesium.

Animals↗