Monoclonal antibody 197 (anti-Fc gamma RI) infusion in a patient with immune thrombocytopenia purpura (ITP) results in down-modulation of Fc gamma RI on circulating monocytes.

A 44-year old woman with refractory immune thrombocytopenia purpura was treated with the murine monoclonal antibody 197 in a phase 1 trial. It vitro studies have demonstrated that the monoclonal antibody 197 (subclass IgG2a) binds to two distinct epitopes of Fc gamma RI, with the constant domain binding to the Fc-binding portion of the Fc gamma RI and the variable domain binding to a different epitope, resulting in crosslinking and modulation of this receptor. The monoclonal antibody 197 was administered on days 1, 3 and 5 at doses of 0.25 mg/kg, 0.35 mg/kg and 0.45 mg/kg, respectively. The fusions were well tolerated with transient facial flushing, and wheal-and-flare rash during the first infusion, which resolved with a slower infusion rate and the administration of diphenhydramine and acetaminophen. Although a marked clinical improvement did occur with resolution of oral ecchymoses and epistaxis after the first mAb infusion, the initial platelet count of 6 x 10(9)/I did not change appreciable over the 5 d course of monoclonal antibody treatment. Binding of fluorescein-labelled monoclonal antibody 197 to peripheral monocytes showed a rapid and persistently decreased mean fluorescein intensity, indicated binding of administered 197 to the monocytes in vivo. Indirect staining for FcgammaRI using fluorescein-labelled goat anti-mouse immunoglobulin was also decreased, suggesting modulation of the receptor. The patient experienced monocytopenia which persisted throughout the 5 d of monoclonal antibody 197 therapy, but reversed following institution of intravenous IgG. These data indicate that intravenous monoclonal antibody 197 induces specific down-modulation of Fc gamma RI expression on monocytes.

Patents and patent office resources in biotechnology.

Patents play an increasingly important role in the dissemination of information in many fast moving fields such as biotechnology and semiconductors. Quite a few new developments are introduced as patents, and only later, if at all, do they find their way into the scientific literature. In spite of this, patents lack wide acceptance as a source of information among scientists in academia and, to a lesser degree, industry. Patents share many similarities with scientific papers. They both are organized in a similar way and are carefully reviewed by experts in the field. Both can be effective and timely sources of information. Patents can be accessed through data bases, library collections, the "Official Gazette of the Patent and Trademark Office," or directly in the Patent and Trademark Office. This article is designed to serve as a guide to the type of information which can be found in patents, and alternatives for obtaining this information.

Use of implantable intraperitoneal diffusion chambers to study Bordetella pertussis pathogenesis: growth and toxin production in vivo.

A new animal model for Bordetella pertussis infection is described. The system utilizes small chambers bounded by 0.22-micron filter membranes. The chambers are inoculated with B. pertussis, sealed, and surgically implanted into the peritoneal cavity of mice. The chamber system allows dynamic interchange of soluble host and bacterial factors, but not cells. We have used this system to study the growth of various clinical isolates and vaccine strains of B. pertussis, including an isogenic virulent/avirulent pair. All virulent strains tested grew well and had remarkably similar growth kinetics. We monitored cellular and humoral host responses, including the response to pertussis toxin. Antitoxin appeared 21-37 days after implantation of the chambers. The model allows us to dissociate the ability of an organism to grow in vivo from other properties (e.g., attachment and toxin production) that may be involved in pathogenesis.

A mathematical model of exoprotein production in bacteria.

We present a simple mathematical model for the synthesis of extracellular proteins by a class of bacteria which secrete significant quantities of this exoprotein in late-exponential and stationary phases. This model is the simplest generalization of Michaelis-Menten kinetics (the Monod model) and agrees well with laboratory experiments in batch culture. The model may serve as a simple prototype for the analysis of certain virulent bacterial infections in vivo, particularly that of Pseudomonas aeruginosa in burn wounds.

Cloned diphtheria toxin fragment A is expressed from the tox promoter and exported to the periplasm by the SecA apparatus of Escherichia coli K12.

The diphtheria toxin fragment A-related polypeptide encoded by the recombinant plasmid pDT201 (Leong, D., Coleman, K. D., and Murphy, J. R. (1983) Science 220, 515-517) and expressed in Escherichia coli K12 was found to have an electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels corresponding to 28,500 daltons. Immunoprecipitation experiments revealed that the mature form of the fragment A-related polypeptide was exported to the periplasmic compartment of E. coli K12 harboring plasmid pDT201. The polypeptide was sensitive to trypsin "nicking." Following treatment an Mr = 24,000 fragment was released which co-electrophoresed with fragment A of diphtheria toxin. The precursor form (Mr = 31,000) of the fragment A-related polypeptide was found to accumulate in the cytoplasmic fraction of the temperature-sensitive secretion-defective strain of E. coli K12 under nonpermissive conditions. We further demonstrate that a 263-base pair HaeIII fragment of pDT201 which carries the putative diphtheria tox promoter has promoter activity in E. coli K12.

Cloned fragment A of diphtheria toxin is expressed and secreted into the periplasmic space of Escherichia coli K12.

An 831-base pair segment of the corynebacteriophage beta tox-45 genome encoding fragment A of diphtheria toxin was cloned into plasmid pUC8 in Escherichia coli K12. Strains containing recombinant plasmids expressed the adenosine diphosphate ribosyl transferase activity characteristic of fragment A; this activity could be inhibited by polyvalent antiserum to fragment A as well as by the appropriate monoclonal antibodies to diphtheria toxin. The transferase activity was secreted into the periplasmic space of E. coli. These findings have implications for the future construction of genetically engineered chimeric toxins.