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Biomedical subjects

J Baum

Publications and source records attributed to J Baum.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Capnometry and capnography as safety factors in anesthesia].

Continuous measurement and monitoring of the expiratory carbon dioxide concentration can be performed with modern measurement devices routinely without any problem today. After a short introduction to measurement techniques the comprehensive monitoring possibilities of this method are described by multiple examples. No only actual disturbances of the ventilation, the circulation and the metabolism, but also malfunction or inadequate control of the anaesthesia machine can be recognized without substantial time delay. But an actual alteration of the CO2 value necessitates careful analysis of the underlying problem which is greatly facilitated by a graphic display of the CO2 signal, the capnogram. The knowledge of possibly occurring artificial alterations of the CO2 measurement, which are demonstrated too, prevents dangerous misinterpretations. By continuous measurement of the expiratory CO2 concentration, not only can the ventilation parameters be set optimally, but multiple life threatening complications can be detected very early and corrected immediately. Thus, this monitoring technique essentially contributes to the patients safety during anaesthesia.

Anesthesia↗
PubMed1991

Neuraminidase activity in acanthamoeba species trophozoites and cysts.

Acanthamoeba species, a widely distributed group of free-living amoeba, can infect humans and spread hematogenously after direct interaction with the mucosal surfaces. The mechanism underlying Acanthamoeba damage to the target cell is unknown. The authors report that trophozoites and cysts of Acanthamoeba species exhibit a neuraminidase activity that is membrane associated and released into the culture medium at the start of the logarithmic phase of growth. The enzyme activity is optimal at pH 5 and at 25-30 degrees C. Live parasites release sialic acid from human cells. Therefore, the neuraminidase of Acanthamoeba species could be relevant in the colonization and damage of the sialic acid-rich corneal epithelium and in the alterations of glycolipids associated with meningoencephalitis.

Acanthamoeba↗
PubMed1991

Auranofin therapy for juvenile rheumatoid arthritis: results of the five-year open label extension trial.

Eighty-eight children with juvenile rheumatoid arthritis (JRA) who completed a double blind, randomized placebo controlled trial of oral gold were entered into an open label extension phase during which they received auranofin (AF) at a dosage of 0.15-0.2 mg/kg/day (9 mg/day maximum). Eleven (12.5%) patients completed 5 years of AF therapy; 77 (87.5%) did not. Fifteen (17%) of the 88 were in disease remission at the final visit. Mean duration of therapy for those who discontinued was 646 days. Parental/patient decision and insufficient therapeutic effect were the 2 most frequent reasons for early termination, followed by adverse effects. Though relatively well tolerated, AF provides adequate longterm management for only a small percentage of patients with JRA.

Administration, Oral↗
PubMed1990

Bacterial adherence to extended wear soft contact lenses.

The authors studied the adherence of Pseudomonas aeruginosa and Staphylococcus aureus to extended wear soft contact lenses (EWSCLs) with and without focal deposits using both a radiolabeling technique and electron microscopy. P. aeruginosa showed significant adherence to contact lenses in vitro. In contrast, S. aureus failed to show significant adherence to contact lenses in vitro (i.e., the radioactive uptake was not significantly above background). The extent of adherence of Pseudomonas was proportional to the number of focal deposits on the lenses. Results of electron microscopic examination showed the bacteria to be adherent primarily to large focal deposits (greater than or equal to 150 microns). There was no pseudomonal adherence to the small focal deposits (less than or equal to 50 microns) and little adherence to the areas in between the focal deposits. The authors hypothesize that worn lenses, especially those with large focal deposits, serve as a vehicle for the transport of P. aeruginosa to the cornea. This hypothesis could be a partial explanation for the high incidence of keratitis caused by P. aeruginosa in EWSCL patients.

Bacterial Adhesion↗
PubMed1990

Binding of Pseudomonas aeruginosa to neutral glycosphingolipids of rabbit corneal epithelium.

35S-labeled Pseudomonas aeruginosa isolates were shown to bind to neutral glycosphingolipids (NGSLs) of rabbit corneal epithelia in culture by a thin-layer chromatogram overlay procedure. The lipids of the corneal epithelial cells grown in culture were extracted and partitioned into a chloroform-rich lower phase containing NGSLs and an aqueous upper phase containing gangliosides. By using a dot-blot assay, at least six times more radiolabeled P. aeruginosa isolates were shown to bind to the lipids in the lower phase compared with those in the upper phase. Thin-layer chromatography of the lower-phase lipids followed by staining with an orcinol spray revealed at least 10 NGSL components and several fast-migrating, nonglycosylated neutral lipid components (including cholesterol). 35S-labeled P. aeruginosa was shown to bind to NGSL components 1, 2, 5, 6, and 9. P. aeruginosa-reactive NGSL components 6 and 9 migrated with chromatographic mobilities similar to those of the standards ceramide trihexoside (CT) and ceramide monohexoside, respectively. Components 1 and 2 migrated slightly ahead of asialo GM1, and component 5 migrated faster than globoside but slower than CT. Among the various standards tested, P. aeruginosa bound to asialo GM1 and, to a lesser extent, to ceramide dihexoside and CT but not to GM1, GD1A, GM3, or ceramide monohexoside. It remains to be determined whether any of the five P. aeruginosa-reactive NGSL components of corneal epithelium identified in this study plays a role in the development of corneal infection. However, we have previously shown that component 9, one of the five P. aeruginosa-reactive NGSL components identified in this study, is present in significantly greater amounts in migrating epithelia than it is in nonmigrating epithelia (N. Panjwani, G. Michalopoulos, J. Song, G. Yogeeswaran, and J. Baum, Invest. Ophthalmol. Vis. Sci., in press). This may prove to be of biological significance because it is generally believed that traumatized (migrating) epithelia are more susceptible to infection than normal (nonmigrating) epithelia are.

Animals↗
PubMed1990

Differential binding of P. aeruginosa and S. aureus to corneal epithelium in culture.

Adherence of bacteria to corneal epithelium is a prerequisite for corneal infection. We used two methods to study the binding of Pseudomonas aeruginosa and Staphylococcus aureus to rabbit corneal epithelial cells in culture. In the first method, rabbit corneal epithelial cells grown on glass slides were incubated with P. aeruginosa or S. aureus (10(7) CFU/ml) at room temperature for 90 min, and the bacterial binding to the epithelial cells was examined by light microscopy. Both P. aeruginosa and S. aureus bound to epithelial cells. P. aeruginosa was bound to the cell periphery whereas S. aureus was bound randomly to the cell surface. In the second method, suspension cultures of corneal epithelial cells were used. In contrast to the findings in cultures on slides, binding pattern with cells in suspension was similar for both species and resembled that for S. aureus in cultures on slides. A much greater number of P. aeruginosa (186 +/- 11 bacteria/epithelial cell) than S. aureus (30 +/- 1.5 bacteria/epithelial cell) bound to epithelial cells grown on glass slides. In contrast, a similar number of P. aeruginosa (25 +/- 5.1) and S. aureus (20 +/- 4.7) bound to epithelial cells grown in suspension cultures. Using either method, Escherichia coli and Streptococcus pyogenes did not bind significantly (less than 5/cell) to corneal epithelial cells. The above methods should prove useful for characterization of bacterial binding to corneal epithelial cells in culture.

Animals↗
PubMed1990

Clinical applications of low flow and closed circuit anesthesia.

Minimal Flow Anesthesia, an extreme technique of semiclosed use of rebreathing systems performed with a fresh gas flow of 0.5 l/min, can be managed with already available anesthesia machines. As a standardized fresh gas volume with fixed composition is used, due to the exponential decrease of the patient's gas uptake, the gas composition within the breathing system may change markedly during the time course of anaesthesia. Nevertheless, by this degree of fresh gas flow reduction, being very close to the patient's gas uptake, the advantages of the rebreathing technique can be achieved nearly extensively. Closed System Anesthesia, however, the anesthetic technique by which just these volumes of oxygen, nitrous oxide, and volatile anesthetics are applied, which are taken up by the patient at the particular time, can't be performed satisfactorily even if highly sophisticated equipment is used. The need for continuous adjustment of the fresh gas controls, the insufficient accuracy of the dosaging systems and the impossibility to calculate precisely the uptake figures in the individual case are essential obstacles for the routine use of this method. An account of the clinical realization of both techniques is given and the specific advantages and disadvantages are considered: although modern anesthesia machines are designed especially for the use of even lowest fresh gas flow rates, quantitative Closed System Anesthesia will not become a technique for routine clinical practice until apparatus with computer-aided closed loop feedback control of the fresh gas supply will be available.

Anesthesia, Closed-Circuit↗
PubMed1990

[Fresh gas flow and artificial respiration in anesthesia. Technical requirements for the adequate use of rebreathing systems].

The majority of modern anaesthetic machines is designed for the rebreathing method. But frequently high fresh gas flows are employed, thus minimising the rebreathing fraction of expiratory gases. However, only by reducing the fresh gas flow substantially, the advantages of the rebreathing technique can be obtained. To evaluate the practicability of flow reduction, minimal flow anaesthesia was carried out with four different anaesthetic machines: AV 1 (Drägerwerk AG, Lübeck), ELSA (Gambro Engström AB, Bromma, Sweden), SULLA 808 V (Drägerwerk AG, Lübeck) und VIVOLEC (Hoyer Medizintechnik, Bremen). Fresh gas flow was reduced to 0.5 l/min after an initial phase of 15-20 min, during which the fresh gas flow was kept at a high level of 4.4 l/min. The minute volumes before and after fresh gas flow reduction were compared. The minute volume decreased markedly and significantly in the SULLA 808 group, whereas it remained nearly unchanged in the AV 1, the ELSA, and the VIVOLEC groups. The differences result from different modes of fresh gas delivery into the breathing circuit. If anaesthetic apparatus that maintain their tidal volume with different fresh gas flow rates are employed, rebreathing systems may be used judiciously by changing the fresh gas flow according to the individual uptake or any particular clinical requirement.

Adult↗
PubMed1990

Neutral glycolipids of migrating and nonmigrating rabbit corneal epithelium in organ and cell culture.

It is generally believed that plasma membrane glycoconjugates influence corneal epithelial cell migration after wounding. Previous studies have focused on the role of glycoproteins in this event. The present study was designed to determine whether migration-specific glycolipids are synthesized by epithelium of healing rabbit corneas. Migrating and nonmigrating rabbit corneal epithelia were incubated with [3H]-galactose in an organ culture system for 48 hr. At the end of the labeling period, a neutral glycosphingolipid (NGSL) fraction was isolated from each radiolabeled epithelium and was analyzed by thin-layer chromatography. Three radiolabeled NGSL components, M1, M2 and M3 (M1-M3), were present in significantly higher amounts in the extracts of migrating as compared to nonmigrating epithelium. Chromatographic mobility of M3 was similar to that of a standard glucosylceramide; M1 and M2 migrated more slowly than M3. For characterization of the migration-related NGSL, a large amount of the starting material is required. Experiments, therefore, were conducted using cell cultures of rabbit corneal epithelium. Confluent (nonmigrating) cell cultures of rabbit corneal epithelium were found to synthesize either minimal or undetectable amounts of NGSL M1-M3. In contrast, we found that the NGSL M1-M3 are synthesized as major components by sparse (migrating) corneal epithelial cell cultures. Components M1-M3 were synthesized as major components by sparse cultures even in the absence of cell mitosis. This suggests that the increased synthesis of components M1-M3 by sparse cell cultures may be related to cell migration rather than cell mitosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Characterization of a partly folded protein by NMR methods: studies on the molten globule state of guinea pig alpha-lactalbumin.

NMR spectroscopy has been used to investigate the structure of a partially folded state of a protein, the molten globule or A-state of alpha-lactalbumin. The 1H NMR spectrum of this species differs substantially from those of both the native and fully unfolded states, reflecting the intermediate level of order. The resolution in the spectrum is limited by the widespread overlap and substantial line widths of many of the resonances. Methods have therefore been developed that exploit the well-resolved spectrum of the native protein to probe indirectly the A-state. A number of resonances of the A-state have been found to be substantially shifted from their positions in the spectrum of the unfolded state and have been identified through magnetization transfer with the native state, under conditions where the two states are interconverting. The most strongly perturbed residues in the A-state were found to be among those that form a hydrophobic core to the native structure. A number of amides were found to be highly protected from solvent exchange in the A-state. These have been identified through pH-jump experiments, which label them in the spectrum of the native protein. They were found to occur mainly in segments that are helical in the native structure. These results enable a model of the A-state to be proposed in which significant conformational freedom exists but where specific elements of native-like structure are preserved.

Animals↗
PubMed1989

Discoid lupus keratitis.

Two patients with long-standing discoid lupus erythematosus developed acute, unilateral, corneal stromal infiltration and edema. No evidence of infection was found, and both responded rapidly to topical corticosteroid therapy. To our knowledge, only one case of stromal keratitis associated with discoid lupus erythematosus has been published previously. We describe the first cases, to our knowledge, in which a satisfactory response to corticosteroid therapy is demonstrated.

Adult↗
PubMed1989

Effect of lid closure on contact lens-associated Pseudomonas keratitis.

New or used extended-wear soft contact lenses, preincubated in suspensions of Pseudomonas aeruginosa, were placed on the corneas of rabbits. The lids were then sutured shut for either 1 or 2 weeks. Bacterial keratitis occurred in 9 of 9 eyes fitted with the used contaminated lenses but in none of 12 eyes fitted with new contaminated or new noncontaminated lenses. Similar experiments were carried out with other lenses specifically designed to fit the cornea of rabbits. Some of these lenses were preworn by rabbits for 1 week (used), whereas others were new. A significantly greater incidence of bacterial keratitis was found in eyes that had undergone lid closure after the placement of used contaminated lenses (4 of 5) than in closed eyes with new contaminated lenses (1 of 8) and in open eyes with used contaminated lenses (0 of 13). These findings suggest that extended eyelid closure is a risk factor in the experimental model and may be a factor in clinical Pseudomonas keratitis associated with the wearing of extended-wear soft contact lenses.

Animals↗