Biomedical subjects

J Gelfand

Publications and source records attributed to J Gelfand.

3 recordsLinked to original sources

PubMed1991

Complement activation by dental implants.

Activation of complement leads to the generation of C3a and C5a inflammatory peptides. C5a is a potent chemotactic factor, stimulating the secretion of proteolytic enzymes by neutrophils and osteoclast activating factor/Interleukin-1 by monocytes. In vitro generation of C3a and C5a was measured by radioimmunoassay techniques. The results showed significant complement activation by all implants tested when compared to the control serum incubation. It is concluded that all of the implants studied activated the complement system and are not physiologically inert. Complement activation, therefore, may contribute either positively to healing or negatively to a poor outcome in osseoadaptation initially or over time.

Complement Activation↗

PubMed1989

De novo membranous glomerulonephropathy in renal allografts: a report of ten cases and review of the literature.

De novo posttransplantation membranous glomerulonephropathy (MGN) is the most common form of de novo glomerulopathy in renal allografts. The clinical and pathological features of ten patients with de novo MGN were studied and the related literature was reviewed to assess the clinical features, morphologic characteristics, and natural course of this disease. De novo MGN may occur in both living related and cadaveric allografts at any time after transplantation. It presents clinically either as asymptomatic proteinuria or the nephrotic syndrome, a feature of poor prognostic implication. Morphologically, de novo MGN in most instances has distinct differences from idiopathic MGN in native kidneys and is accompanied by varying features of rejection. About 50% of grafts which develop de novo MGN eventually fail. This rather poor outcome may not represent the natural history of de novo MGN per se but rather the consequences of associated chronic rejection. Evidence is presented that many of the cases of so-called de novo MGN may be a complication of transplant glomerulopathy rather than being caused by mechanisms totally independent from rejection.

Cadaver↗

PubMed1989

Electromechanical analogs of human reflexes.

The conclusion to be drawn from our modeling is that the combined stretch and tendon reflexes alone can endow artificial muscle with a springlike feel as well as give it a baseline tone. In response to questions that motor physiologists often ask as to what variables the system controls, the answer here is clear: the stretch and tendon reflexes act together to maintain both a tension set-point and a length set-point, but in so doing they also give the system a springlike feel because of the existence of a servo error. The main goal of our studies is to understand the integration of reflexes, and thus far we have only begun to explore the two lowest-level spinal reflexes. We are in the process of expanding this work by developing a much more refined arm explicitly modeled after the human arm. This new arm is to be activated by a minimum of 10 muscles, each of which is reflexively driven, and it will allow us to explore the integration of higher-level reflex action such as automatic inhibition of antagonists and facilitation of synergists.

Humans↗