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Biomedical subjects

R Jenny

Publications and source records attributed to R Jenny.

13 recordsLinked to original sources
PubMed1991

[Vascular complications associated with aortic dissection].

Aortic branch occlusion may constitute the mode of presentation or become an important focus of treatment in patients sustaining acute aortic dissection. The optimal therapeutic approach in patients with acute aortic dissection complicated by cerebral, visceral and peripheral vascular problems, and the implications of such complications, are not well established. We review the outcome in 187 consecutive patients (149 males and 38 females, mean age 58 years) with acute dissection of the thoracic aorta who were admitted and operated on in our department over a 13-year period. We assess the incidence, consequences and specific management of significant stenotic and obstructive lesions of the aorta and its branches. Noncardiac vascular complications occurred in 59 patients (32%); of these complications, 38 were associated with type A dissection (incidence 28%) and 21 with type B dissection (incidence 48%). A trend towards decreasing overall surgical mortality was observed in the second part of the study (1983-1989) compared with the first part (1977-1982) i.e. 28% versus 12%. Although aortic rupture and cardiac tamponade were the strongest correlate of morbidity and mortality, death specifically related to vascular complication was more common when such malperfusion occurred in the carotid, celio-mesenteric and renal circulation. Proximal aortic repair at the site of the intimal tear with obliteration of the false lumen may have restored adequate distal circulation in 27 patients in whom improvement of the visceral or peripheral ischemia was observed after the thoracic aortic repair. Additional procedures (immediately after the thoracic repair or later) were necessary in 15 patients to restore adequate perfusion in the compromised area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Fixed partial denture on osseointegrated screw implants].

There are many differences between full dentures on Brånemark implants and fixed partial dentures built on the same type of implants: due to some more critical anatomical conditions, the choice of number, position and length of the implants is more delicate; the need of an harmonious crown-gingival tissue relationship; higher occlusal forces than in edentalous cases; difficulty in satisfying aesthetic requirements and ease of hygiene. The surgical treatment plan, a pre-requesite to any surgery, permits to determine the length of implants, their number, their position, their long axis direction and the design of the surgical guide, which will indicate to the surgeon the location and the axis for drilling. If this axis is nearly parallel to the sagittal plane for mandibular implants, it will be angulated to that same plane for maxillary implants. In the latter cases, it is often necessary to use angulated transepithelial abutments in order to prevent the abutment screw from having an occlusal access. In order to perform the prosthetis, an impression should be taken with the transepithelial abutments. The final reconstruction can be preceded by a temporary prosthesis, then (or) transitory to await gingival stabilization and not overload the implant immediately after it has been connected with the abutment. The fixed partial denture can be secured with screws or cemented when it is of small size and it must satisfy the functional and aesthetic requirements of the patient. The choice of the material used on the occlusal surface is very important and varies depending on the case. Aesthetics should not be prevent an in easy hygiene. These objectives are not reached at the time the prosthesis is made but during the course of the surgical and prosthetic treatment. Single restorations are subjected to the rules pertaining to any fixed partial denture on implants, but have particular characteristics, such as the almost systematic elimination of the abutment and the absolute necessity of the correct placement of the implant. The single units are more easily subject to unscrewing for mechanical reasons. Although the use of implants is a valuable aid in cases of partial fixed restoration, it requires particular attention with regard to precision.

Dental Implantation, Endosseous↗
PubMed1988

Evidence that the thrombin-catalyzed feedback cleavage of fragment 1.2 at Arg154-Ser155 promotes the release of thrombin from the catalytic surface during the activation of bovine prothrombin.

During the course of prothrombin activation, as catalyzed by Factor Xa, Factor Va, Ca2+, and negatively-charged phospholipid vesicles, the three proteins distribute between the fluid phase and the vesicle surface. On the vesicle, efficient Factor Xa-catalyzed proteolysis yields thrombin plus Fragment 1.2. Further thrombin-catalyzed feedback cleavage of the latter then yields Fragment 1 plus Fragment 2. Prior to this cleavage Fragment 1.2 might retain thrombin at the site of catalysis since it binds both phospholipid and thrombin through its respective Fragment 1 and Fragment 2 domains. In order to study the role of the feedback cleavage, light scattering at right angles was used to deduce the nature of the components associated with the vesicle during prothrombin activation by continuous monitoring of the relative molecular weight of the vesicle-protein complex. When prothrombin (1.4 microM) was added to homogeneously sized phospholipid vesicles of phosphatidylcholine-phosphatidylserine (3:1) at a total phospholipid concentration of 20 microM, the scattering intensity doubled. Upon subsequent addition of Factor Xa and Factor Va (5.0 nM each) the scattering intensity smoothly decreased to a value about 1.25-fold greater than that of the vesicles alone. Analysis of the composition of the reaction mixture at intervals during the course of the reaction by gel electrophoresis and laser densitometry, provided a good correlation between the mass of the vesicle-protein complex measured by light scattering and its mass inferred by composition. In addition, the decrease in mass of the vesicle-protein complex measured by light scattering correlated temporally with cleavage of Fragment 1.2. When the reaction was initiated in the presence of the reversible thrombin inhibitor dansylarginine-N-(3-ethyl-1,5-pentanediyl)amide no cleavage of Fragment 1.2 occurred, as indicated by gel electrophoresis, and no change in the mass of the vesicle-protein complex occurred as indicated by light scattering. The absence of change in scattering intensity in the presence of dansylarginine-N-(3-ethyl-1,5-pentanediyl)amide suggests a 1:1 replacement of prothrombin at the catalytic surface by components of equivalent mass (Fragment 1.2 plus thrombin), whereas the decrease in scattering in the absence of dansylarginine-N-(3-ethyl-1,5-pentanediyl)amide suggests replacement of prothrombin by Fragment 1 only. Together these results indicate that the thrombin-catalyzed cleavage of Fragment 1.2 promotes release of thrombin from the catalytic surface.

Algorithms↗
PubMed1986

Purification of six human vitamin K-dependent proteins in a single chromatographic step using immunoaffinity columns.

The major human vitamin K-dependent proteins were purified from plasma using immunoadsorbents made with antibodies specific for each protein. Monoclonal antibodies to Factor VII, Factor IX, Factor X, Protein C, and Protein S were prepared from mice immunized with isolated vitamin K-dependent antigens. Purified monoclonal antibodies and a purified burro polyclonal anti-prothrombin immunoglobulin were individually coupled to Sepharose and used in a tandem series of columns to purify each of the vitamin K-dependent proteins from eluates of barium citrate precipitates of plasma. The proteins were eluted from the columns by sodium thiocyanate and retained functional activity following dialysis. Prothrombin, Factor VII, Factor IX, Factor X and Protein C were essentially homogeneous as judged by NaDodSO4-PAGE; Protein S was isolated as a Protein S-C4b binding protein complex. These results indicate the utility of monoclonal antibody immunoadsorbents for purifying the human vitamin K-dependent proteins and represent a considerable simplification over other purification schemes.

Antibodies, Monoclonal↗