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Biomedical subjects

J Johnson

Publications and source records attributed to J Johnson.

At least 559 records · Page 31Linked to original sources
PubMed1986

Stippled ribs: a potential pitfall in bone scan interpretation.

A retrospective evaluation of 100 consecutive bone scans was performed to determine the incidence and clinical importance, if any, of increased uptake at the insertion of the iliocostalis thoracis portion of the erector spinae muscle group (rib stippling). Rib stippling was deemed present if a focal area of increased technetium-99m methylene diphosphonate [( 99mTc]MDP) was identified within the posterior angle of three or more consecutive ribs. Seven of 100 (three bilateral, four unilateral) patients demonstrated rib stippling. Foci intensity was less than the scapular tips, but greater than the adjacent ribs. No patient had a history of chest trauma, pain and/or an abnormal radiograph. Even though increased uptake within the posterior angle of the ribs is an uncommon finding (7%), its recognition as a normal bone scan finding is important to prevent bone scan misinterpretations. Its characteristic scintigraphic appearance and location should serve to differentiate it from the increased uptake of trauma and/or tumor.

Back↗
PubMed1985

Spin label studies of the essential sulfhydryl group environment in chicken liver fructose-1,6-bisphosphatase.

The local environment of the essential sulfhydryl groups in chicken liver fructose-1,6-bisphosphatase has been investigated by ESR techniques using a series of iodoacetamide spin labels, varying in chain length between the iodoacetate and nitroxide free radical group. The ESR spectrum of spin-labeled chicken liver fructose-1,6-bisphosphatase showed that the sites of labeling were highly immunobilized when the enzyme was chemically modified by spin label iodoacetate, suggesting that the sulfhydryl groups of the protein are in a small, confined environment. From the change in the ESR spectra of these nitroxides as a function of chain length, we conclude that the sulfhydryl group is located in a cleft approx. 10.5A in depth.

Animals↗
PubMed1985

Immobilization of chicken liver fructose 1,6-bisphosphatase on CNBr-activated Sepharose.

Chicken liver fructose 1,6-bisphosphatase is readily immobilized on CNBr-activated Sepharose. The immobilization alters some enzymatic properties. They include broader pH activity curve, loss of activation by K+ or NH+4, increased resistance to inactivation by trypsin, decreased sensitivity to AMP inhibition, and loss of cooperative interaction among AMP-binding sites. The immobilized enzyme retains about 38% or 19% of the specific activity of the native enzyme when the activity is measured in the absence or presence of K+, respectively.

Adenosine Monophosphate↗
PubMed1985

Maternal, fetal, and newborn tissue PO2 in sheep measured with galvanic oxygen electrodes.

Tissue PO2 was measured with galvanic oxygen electrodes chronically implanted in maternal and fetal tissues of two pregnant ewes. Labor commenced after 3 days in one ewe and after 11 days in the other. Tissue PO2 was measured in both newborn lambs. Fetal tissue PO2 during labor was less than 3 mm Hg but rose to values similar to those found in adult tissues in the newborn period. Function of the electrode and response of the tissue to change in oxygenation was challenged by administration of 100% oxygen to the pregnant ewe or newborn lamb, and by administration of intravenous epinephrine to the ewe. These tests suggested that all electrodes were functioning satisfactorily in vivo and that tissue PO2 was responding as anticipated. Recalibration of electrodes after removal from the tissues confirmed that their response in vitro was similar to that obtained before implantation.

Animals↗
PubMed1985

Removal of epimacular membranes.

Vitreous surgery was used to remove epiretinal macular membranes in 328 cases, 184 (56%) of which had membranes that were considered idiopathic and 144 (44%) which were due to other causes. The 12- to 92-month follow-up showed that visual acuity improved two lines or more in 243 (74%) of the eyes, 79 (24%) were unchanged and 6 (2%) became worse. Recurrence of membranes was seen in 24 (7.3%) eyes and 27 (8%) eyes developed complications. In the idiopathic cases visual results were significantly better and complications fewer. Rapidly progressive nuclear sclerosis was noted in 23 (12.5%) eyes. The degree of cystoid edema had no relationship to the final visual result. Pseudoholes which were present in 14 (8%) of the idiopathic cases either became smaller or disappeared following successful surgery with an average increase in acuity of five lines.

Adolescent↗
PubMed1985

Tumorous lesions of the hand.

A retrospective study was conducted of 543 tumorous lesions of the hand seen in a busy office practice for a 5-year period from April 1976 to April 1981. The lesions were grouped as benign lesions, of either the soft tissue or skeletal type, or as malignant lesions. The overall chance that a hand tumor was malignant was 2% (11 of 543). There was significant association of palmar radial ganglion and carpal tunnel syndrome (15%). Ganglions recur more often after aspiration than after surgery. Certain lesions, particularly a mucous cyst, have a high postoperative complication rate. A few of these unique lesions are described.

Adult↗
PubMed1985

Lethality of intestinal tissue extracts from Eimeria-infected chickens.

Evidence exists that lethal activity is associated with extracts from Eimeria tenella-infected caecal tissues. We examined tissues of the small intestine infected with other species of Eimeria for a similar lethal activity. Extracts were prepared from intestinal tissues of chickens infected with either E. acervulina, E. brunetti, E. maxima, E. mitis or E. necatrix. Appropriate control extracts from tissues of non-infected chickens were also prepared. Intravenous injection of the extracts into healthy chickens showed that lethality of infected tissue extracts was higher than control extracts and was independent of the site of infection within the intestine. Comparison of the lethality of caecal extracts from chickens infected with embryo-adapted or parent lines of E. tenella showed that lethality was independent of the recognized pathogenic characteristics of the lines. Also, it was demonstrated that lethal activity is associated with extracts of tissues containing massive numbers of arrested and non-arrested sporozoites and early trophozoites.

Animals↗
PubMed1985

The clearance of Xenon-133 following its parenchymal injection: a rapid method for estimating functional liver blood-flow.

Portal venous flow, total hepatic blood-flow and hepatic artery flow were measured in healthy dogs by electromagnetic flowmetry and a double indicator dilution technique. Functional liver blood-flow was measured by the double indicator dilution technique. Functional hepatic blood-flow did not correlate with portal venous flow, total hepatic blood-flow or hepatic artery flow, measured by either electromagnetic flowmetry or a double indicator dilution technique. There was a good correlation (r = 0.83, P less than 0.001) between functional hepatic blood-flow and liver blood-flow, measured by the clearance of Xenon-133 injected directly into the liver parenchyma. It is concluded that the clearance of Xenon-133, injected directly into the liver parenchyma, is a rapid and simple method for measuring functional hepatic blood-flow.

Animals↗
PubMed1985

Selective inhibition of the accumulation of extracellular proteases of Pseudomonas aeruginosa by gentamicin and tobramycin.

Gentamicin and tobramycin inhibited the accumulation of extracellular proteases secreted by Pseudomonas aeruginosa. The secretion of protease was inhibited at concentrations of these drugs that were below the level required to inhibit general protein synthesis. Neither magnesium ions nor high ionic strength antagonized the ability of the aminoglycosides to block secretion of the proteases. Under these culture conditions magnesium ions were shown to antagonize the effects of the aminoglycosides on protein synthesis and aminoglycoside-mediated lysozyme lysis of P. aeruginosa. These results suggested that the drugs blocked secretion of the proteases by acting at the level of the outer membrane.

Culture Media↗
PubMed1985

Increasing the independent responding of autistic children with unpredictable supervision.

We investigated the role of predictable versus unpredictable supervision on the independent task responding of three autistic children. In a predictable supervision condition, the therapist was present in the setting for a regular period of time and then was absent for the remainder of the session. In an unpredictable supervision condition, the therapist's presence was scheduled on a random, intermittent, and unpredictable basis throughout the session. The multiple baseline analysis showed that the unpredictable supervision produced much higher levels of on-task responding during the therapist's absence for all three children. Analysis of work completed during the therapist's absence also favored the unpredictable supervision condition. The results are discussed in relation to the literature on generalization and educational practice.

Autistic Disorder↗
PubMed1985

CT of perineural tumor extension: pterygopalatine fossa.

Tumors of the oral cavity and paranasal sinuses can spread along nerves to areas apparently removed from the primary tumor. In tumors of the palate, sinuses, and face, this "perineural" spread usually involves the maxillary division of the trigeminal nerve. The pterygopalatine fossa is a pathway of the maxillary nerve and becomes a key landmark in the detection of neural metastasis by computed tomography (CT). Obliteration of the fat in the fossa suggests pathology. Case material illustrating neural extension is presented and the CT findings are described.

Adult↗
PubMed1985

Eimeria tenella: relative survival of drug-resistant and drug-sensitive populations in floor pen chickens.

The effect was studied of introducing about equal numbers of decoquinate-sensitive or decoquinate-resistant Eimeria tenella oocysts into a floor pen of susceptible unmedicated chickens. "Sentinel" birds introduced 2, 3, 4, 5, and 6 weeks later were used to recover populations of E. tenella oocysts. In drug sensitivity tests, populations of oocysts harvested at 4 weeks were partially resistant to decoquinate medication. Oocysts obtained after 5 and 6 weeks were highly sensitive to decoquinate medication. The results indicate that drug-sensitive E. tenella parasites are more likely to dominate in absence of medication.

Animals↗