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Biomedical subjects

J Johnson

Publications and source records attributed to J Johnson.

At least 505 records · Page 28Linked to original sources
PubMed1988

Tetanus--a continuing problem in minor injuries.

Tetanus is rare in North America because of highly effective specific immunization programs. Nevertheless, 15 patients with generalized tetanus were treated at the Vancouver General Hospital over a 20-year period; 10 of them were over 50 years of age. Two patients had no injury and 12 had suffered only minor wounds. None had received previous immunization and, even after wounding, prophylaxis was unsatisfactory in all cases. Nine patients required intensive care and two died. Positive cultures were obtained in only two cases. Four recommendations are made to prevent tetanus: (a) all wounds should be considered "tetanus-prone", (b) an accurate history of immunization should be obtained, (c) more attention should be given to prophylaxis at the time of injury and (d) patients should record vaccinations.

Adult↗
PubMed1988

Conjugate view gamma camera method for estimating tumor uptake of iodine-131 metaiodobenzylguanidine.

Therapy with [131I]MIBG has produced partial remissions of malignant pheochromocytomas but not all patients respond. Responses correlate with the quantity of radiation delivered. We developed the conjugate-view method of imaging using 131I reference sources of known radioactivity placed on the surface of the patient and standard nuclear medicine equipment (gamma camera and computer), to estimate tumor uptake of [131I]MIBG. Such an estimate is a first step toward calculating radiation absorbed dose. Three different methods of background subtraction were evaluated with an anthropomorphic phantom and in five patients. In phantom results, measured tumor activity decreased exponentially with a half-life in agreement with that of 131I to within 3%. However, in the phantom studies, in which non-tumor activity is zero, no single method of background subtraction is superior. In patients, two background subtraction methods, which take their estimate from regions immediately surrounding or adjacent to the tumor and reference source, are less sensitive to reference source position and appear more accurate than a third method which uses a background region of interest displaced from the tumor. The agreement of the calculated activity concentration (nCi/g) with that measured by counting portions of the excised tumors gives validation to the method.

3-Iodobenzylguanidine↗
PubMed1987

Molecular cloning of Clostridium difficile toxin A gene fragment in lambda gt11.

Toxin A of Clostridium difficile has been purified and monospecific antiserum produced. A reliable procedure for isolation and restriction of C. difficile chromosomal DNA was developed which allowed for the construction of a genomic library in lambda gt11. Approx. 35,000 plaques were screened using anti-toxin A which resulted in the identification of one stable positive clone, lambda cd19. Verification of the immunological identity of the isolated toxin A gene fragment in lambda cd19 was determined by affinity purifying toxin A antibodies specific for lambda cd19 gene product, and using these selected antibodies to probe a Western blot of purified toxin A. The insert in lambda cd19 was demonstrated to be a 0.3 kb fragment by restriction digestion, and by hybridization of the clone to a chromosomal digest of C. difficile. The peptide coded for by the toxin A gene fragment in lambda cd19 was not cytotoxic for 3T3 mammalian tissue culture cells.

Bacterial Toxins↗
PubMed1987

Radionuclide imaging in the diagnosis of hernias related to peritoneal dialysis.

Abdominal hernias are noted with increasing frequency in association with peritoneal dialysis as this mode of dialysis becomes increasingly popular. These hernias often present as localized groin edema, without evidence of a mass, on physical examination. Diagnosis is more difficult when the edema encompasses both groins. Radionuclide imaging peritoneography offers a safe, simple, well-tolerated, highly accurate method of localizing peritoneal defects. We used this method to locate and lateralize inguinal hernias in three patients receiving continuous ambulatory peritoneal dialysis who presented with bilateral scrotal edema and who had unrevealing physical examination findings. All three had unilateral, indirect inguinal herniorrhaphies under local anesthesia and have returned successfully to peritoneal dialysis without complication.

Aged↗
PubMed1987

Genetic analysis of NF1: identification of close flanking markers on chromosome 17.

The gene causing von Recklinghausen neurofibromatosis, or NF1, has been more precisely localized in the pericentromeric region of chromosome 17. Narrowing of the location for the disease became possible through the identification of eight new DNA probe genetic markers in the centromeric region. Markers that closely flank the centromere also closely flank the NF1 gene. Although there was evidence against this localization in one recombinant, a review of the clinical records revealed a borderline diagnosis of NF1. Significant sex differences in recombination were observed in the pericentric region, and odds for different orders were less discriminating when sex differences were considered in multilocus analyses. The location of the NF1 gene with respect to the centromere could not be determined because recombinants between NF1 and the centromere were not detected in the set of families tested.

Animals↗
PubMed1987

Indium-111 platelet scintigraphy and two-dimensional echocardiography for detection of left ventricular thrombus: influence of clot size and age.

Two-dimensional echocardiography and indium-111 platelet scintigraphy were performed on 50 dogs to determine the influence of clot age and size on the detection of experimentally induced left ventricular mural thrombus. Thrombus was induced by apical infarction and injection of a sclerosing agent and thrombin. The animals were classified into four groups according to the time of indium-111 platelet injection after thrombus induction: Group I (17 dogs, 1/2 hour after induction; 3 dogs, before induction), Group II (12 dogs, 24 hours after induction) and Group III (12 dogs, 1 week after induction). In Group IV (six control dogs) apical infarction was produced, but thrombin was not injected; indium-111 platelets were injected 1/2 to 1 hour after infarction. The dogs were studied by indium-111 platelet scintigraphy and by two-dimensional echocardiography 1/2 to 5 hours (Group I) and 1 to 5 and up to 72 hours (Groups II to IV) after platelet administration and before death was induced. Two-dimensional echocardiography showed the best overall sensitivity for detection of acute thrombus (97%; 29 of 30). The sensitivity of indium-111 platelet scintigraphy was 86% (18 of 21) for clots greater than or equal to 0.08 ml in size, and 67% (20 of 30) for detection of all clots. Thrombus did not form in 14 dogs of Groups I to III and in 6 of 6 control dogs. The specificity of scintigraphy was 100% (20 of 20) compared with 80% (16 of 20) for echocardiography. Echocardiography was more sensitive than scintigraphy for detecting very small clots in this experimental model.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1987

Synthesis and antimalarial effects of 4-[(7-chloro-4-quinolinyl)amino]-2-[(diethylamino)methyl] -6-alkylphenols and their N omega-oxides.

A series of 4-[(7-chloro-4-quinolinyl)amino]-2-[(diethylamino)methyl]-6-alkylphenols and their N omega-oxides were synthesized by the condensation of 4,7-dichloroquinoline and 4,7-dichloroquinoline N omega-oxide with appropriately substituted 4-amino-2-[(diethylamino)methyl]-6-alkylphenol dihydrochlorides. The latter precursors were prepared in a six-step synthesis starting from available 2-alkylphenols. Several of the title compounds display potent antimalarial activity in mice.

Aminoquinolines↗