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At least 487 records · Page 27Linked to original sources
PubMed1993

Purification and characterization of a potent 70-kDa thiol lysyl-proteinase (Lys-gingivain) from Porphyromonas gingivalis that cleaves kininogens and fibrinogen.

We isolated an enzyme from a major periodontal pathogen, Porphyromonas gingivalis (also called Bacteroides gingivalis), that is capable of initially increasing the coagulant activity of high molecular weight kininogen (HK), releasing bradykinin from HK and low molecular weight kininogen (LK), and destroying the light chain (coagulant portion) of HK. This enzyme, a membrane-bound thiol proteinase that preferentially cleaves the P1-Lys position of tripeptide substrates, is also able to rapidly render fibrinogen nonclottable. We will refer to this enzyme as lys-gingivain because of its origin from P. gingivalis, its classification as a thiol proteinase, and its action as a lysyl-amidase. The activity of lys-gingivain is enhanced by beta-mercaptoethanol, and the enzyme has a molecular mass of 68-70 kDa, a pH optimum of 7.4, and is not inactivated by plasma protease inhibitors. The second-order rate constant for the destruction of the coagulant activity of the HK light chain (surface-binding domain) at 23 degrees C is 2.3 x 10(7) M-1 s-1, and, for cleavages that render fibrinogen unclottable, is 2.05 x 10(6) M-1 s-1. These data suggest that lys-gingivain is a very potent proteinase that would be fully functional in anaerobic periodontal crevices and might participate in the pathogenesis of periodontitis. Lys-gingivain appears to be the most potent kininogenase and fibrase to be described to date.

Amino Acid Sequence↗
PubMed1992

[Treatment of diabetic retinopathy using panretinal laser coagulation].

The author presents an account of his experience with panretinal photocoagulation by means of greenish-blue light of an argon laser in diabetics. He evaluates the technique of treatment. In a group of 156 eyes of 103 patients 1-18 months after photocoagulation with a mean follow-up period of nine months the author compares the development of visual acuity after treatment. Based on these findings he describes the success and asset of treatment for the patient. After one year in 62% of 63 investigated eyes deterioration of visual acuity was arrested, in 16% improvement was achieved. After one and a half year 64% of 33 followed up patients were stabilized, in 12% the visual acuity was still better than at the onset of treatment. Panretinal photocoagulation by means of an argon laser can be considered at present the most effective treatment of diabetic retinopathy.

Adult↗
PubMed1992

Treatment of congenital tracheoesophageal fistula by endoscopic laser coagulation: preliminary report of three cases.

Three newborns with congenital tracheoesophageal fistula were treated by endoscopic laser coagulation. After radiologic and endoscopic diagnosis, laser coagulation of the mucosal layer of the fistula followed using Nd:YAG laser light transferred through an uncovered quartz fiber of 600 microns diameter. The successful and uneventful course in two cases contrasts with the incomplete obliteration in one case caused by inadequate energy application and/or early localized instillation of contrast medium for radiologic control examination. The advantages of this method include elimination of an operative procedure, exclusion of operative complications, and the possibility of repetition in recurrent cases. Care must be taken to prevent esophageal and tracheal damage by use of this method.

Bronchoscopy↗
PubMed1998

Photothermal removal of telangiectases of the lower extremities with the PhotodermVL.

BACKGROUND: Telangiectases of the lower extremities have been refractory to permanent ablation by photothermal coagulation. In addition, adverse effects often occur because of nonselective absorption of the light by the overlying skin. OBJECTIVE: This study was performed to determine the effectiveness and the incidence of adverse effects associated with the PhotodermVL in the treatment of telangiectases, less than 0.4 mm in diameter, of the lower extremities. METHODS: Seventy-two patients were treated, each at one treatment site, by means of a treatment protocol designed by ESC Medical Systems, Ltd., the developer and manufacturer of the PhotodermVL. RESULTS: Complete, or almost complete, clearance of telangiectases was observed in 10% of patients. No improvement occurred in 56% of treated telangiectases, and 25% had partial clearing. Adverse effects were common, including scarring in 21% of patients. CONCLUSION: The PhotodermVL provided a low rate of success in the treatment of telangiectases on the lower extremities. Treatment was associated with a high rate of adverse effects.

Adolescent↗
PubMed2000

Pulsed laser-induced thermal damage in whole blood.

An investigation of the effects of laser irradiation with a wavelength of 532 nm and pulse duration of 10 ms on whole blood was performed in vitro. Threshold radiant exposures for coagulation were quantified and transient radiometric temperatures were measured. The progression of effects with increasing radiant exposure--from evaporation to coagulation-induced light scattering to aggregated coagulum formation to ablation--is described. Results indicate that coagulation and ablation occur at temperatures significantly in excess of those assumed in previous theoretical studies. An Arrhenius rate process analysis based on hemoglobin data indicates good agreement with experimental results.

Biomedical Engineering↗