Biomedical subjects

D K Johnson

Publications and source records attributed to D K Johnson.

95 records · Page 6Linked to original sources

PubMedDate not supplied

Structure-function relationships in indium-111 radioimmunoconjugates.

Conjugates formed by reaction of monoclonal antibody B72.3 with benzyl isothiocyanate derivatives of four amino polycarboxylate chelators (NTA, EGTA, EDTA, DTPA) were labeled with indium-111 and administered iv to athymic mice bearing antigen-positive (LS174T) and antigen-negative (A375) human tumor xenografts. Conjugate immunoreactivities, antibody dose, and xenograft size were controlled, so that the effects of varying chelate structure could be evaluated under conditions where immunological and physiological factors were effectively held constant. Tissue distribution and excretion of the radiometal at 24 and 48 h postinjection were shown to correlate directly with chelate thermodynamic stability (NTA less than EGTA less than EDTA less than DPTA). Radioactivity levels in the blood and the LS174T xenograft increased, while kidney levels and excretion levels decreased, with increasing chelate stability. The kidney was the only normal organ that accumulated non-antibody-bound 111In, uptake of radioactivity into all other tissues, and in particular the liver, being unaffected by changes in chelate structure. Mean transferrin saturation in the tumor-bearing athymic mice was found to be 65%. It is proposed that uptake of free 111In by serum transferrin is precluded in this model, leading to the observed renal localization of unbound label. Kidney:blood and kidney:LS174T activity ratios at 48 h postinjection provided the most sensitive indices of conjugate instability in vivo, spanning 50- and 20-fold ranges, respectively, between the least stable and the most stable conjugate. It is concluded that this antigen/antibody system and mouse model are well-suited to structure-function studies of immunoglobulin labels.

Animals↗

PubMedDate not supplied

High resolution X-ray computed tomography: an emerging tool for small animal cancer research.

Dedicated high-resolution small animal imaging systems have recently emerged as important new tools for cancer research. These new imaging systems permit researchers to noninvasively screen animals for mutations or pathologies and to monitor disease progression and response to therapy. One imaging modality, X-ray microcomputed tomography (microCT) shows promise as a cost-effective means for detecting and characterizing soft-tissue structures, skeletal abnormalities, and tumors in live animals. MicroCT systems provide high-resolution images (typically 50 microns or less), rapid data acquisition (typically 5 to 30 minutes), excellent sensitivity to skeletal tissue and good sensitivity to soft tissue, particularly when contrast-enhancing media are employed. The development of microCT technology for small animal imaging is reviewed, and key considerations for designing small animal microCT imaging protocols are summarized. Recent studies on mouse prostate, lung and bone tumor models are overviewed.

Animals↗

PubMedDate not supplied

Electrocardiographic examination of dental patients with systemic lupus erythematosus.

Cardiac complications and abnormalities associated with systemic lupus erythematosus (SLE) have been well described. The most well-recognized cardiac myopathies in SLE are pericarditis and valvular problems such as verrucous endocarditis. Electrocardiogram (EKG) abnormalities and arrhythmias have also occurred and such individuals may have persistent tachycardia. To determine the prevalence of dental patients with SLE who have these EKG changes, a pilot study was designed in which a group of 13 subjects with SLE underwent EKG monitoring in the clinic. Most of these were patients referred to the oral medicine clinic. A randomly selected group of age-gender matched controls were monitored in an identical manner. All subjects first completed a cardiac screening questionnaire, were comfortably seated, and then monitored. The results indicated that the overall prevalence of EKG abnormalities among the subjects with SLE was 61.5% (n = 8). The most common arrhythmia was supraventricular extrasystoles. These were compared with a control group with a prevalence of 23% (n = 3). Of the 76.9% of the subjects with SLE who reported a positive history of cardiac abnormalities, 80% demonstrated EKG abnormalities as compared with 50% of the control group. Of the subjects with SLE who did not report a previous history, none demonstrated EKG abnormalities as was the same for the control group. These results indicate a high prevalence of EKG abnormalities in dental patients with SLE, especially those with a positive cardiac history.

Adult↗

PubMedDate not supplied

Supplementation of total parenteral nutrition solutions with ferrous citrate.

Daily infusion of a total parenteral nutrition (TPN) formulation containing 1 liter of 5.5% Travasol provides less than 0.1 milligrams of iron. By comparison, a formulation which includes a liter of 10% Travamin provides 2 milligrams of iron per day. To meet iron requirements in patients infusing formulations containing Travasol, iron was added as ferrous citrate. In in virto experiments, 74% of this iron was available to transferrin. In seven patients in whom in vivo availability was tested by red cell incorporation, the mean availability was 81%. Ferrous citrate is recommended as a safe, effective additive to TPN solutions for adult patients requiring iron supplements.

Adult↗

PubMedDate not supplied

Prevalence of Legionella in pharyngeal secretions of patients with pharyngitis.

A serological investigation has suggested that Legionella pneumophila may be associated with sore throat in adults. In a study of 177 adults and children with acute pharyngitis, Legionella species were not isolated from pharyngeal cultures, which utilized selective and nonselective buffered charcoal-yeast extract media. Group A beta-hemolytic streptococci were isolated from 14 percent of the 177 symptomatic patients. Throat cultures from 88 asymptomatic control subjects were negative for Legionella and beta-hemolytic streptococci. Further studies are needed to determine if Legionella species are associated with acute pharyngitis.

Adult↗