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Biomedical subjects

J Johnson

Publications and source records attributed to J Johnson.

At least 649 records · Page 36Linked to original sources
PubMed1982

Determination of cefoperazone concentration in serum and muscle tissue with a versatile high-pressure liquid chromatographic method.

A rapid, specific, and reproducible high-pressure liquid chromatographic method was developed for the determination of cefoperazone concentration in serum and tissue. The assay uses a simple methanol extraction, with cefoxitin as the internal standard. The limits of detection are 1 to 150 micrograms/ml; the maximum coefficient of variation is 7.4%. Using the same chromatography column, muBondapak phenyl, and mobile-phase 0.005 M tetrabutylammonium buffer-acetonitrile (80:20), the method can be easily adapted for the analysis of cefoxitin and moxalactam.

Cefoperazone↗
PubMed1982

Immunogenetic studies in essential hypertension among black patients. I. Correlative studies of serum autoantibody formation.

Serum antinuclear antibody (ANA) and HLA phenotype frequency were studied in 100 black subjects with essential hypertension and 100 normotensive black controls matched for age and sex. 11% of hypertensive individuals had a positive serum ANA test compared with 2% of controls (p less than 0.01). Among the hypertensive patients, positive serum ANA test was seen exclusively in patients who were receiving treatment with methyldopa. Although ANA also correlated with hypertensive vascular damage as assessed by retinal and EKG abnormalities, this was believed to have been due to the higher dose of methyldopa that may have been required to treat hypertension in these more severe cases. A statistically significant correlation of HLA-A11 and HLA-B12 with hypertension was observed, but only studied when uncorrected for the number of HLA specificities. It was concluded that autoantibody formation in essential hypertension is most likely to have been a consequence of antihypertensive drug therapy. In addition, further studies using larger number of patients and controls might more clearly establish the question of whether or not HLA is associated with essential hypertension.

Adult↗
PubMed1982

Prospective research with vulnerable children and the risky art of preventive intervention.

The Vermont Vulnerable Child Development Project is presented as an example of community based preventive intervention research employing multiple control groups and prospective epidemiology. Discussion emphasizes both methodological issues and the pragmatics involved in choosing to use community institutions in order to study preventive interventions for very young multi-risk children living with their mentally disturbed parents. Further, a rationale is provided for anticipating and coping with the political, sociological and personality conflicts which are probably inescapable in this type of mental health research.

Child↗
PubMed1982

Specific factor VIII-related antigen fragmentation: an in vivo and in vitro phenomenon.

Factor VIII concentrates have been shown to have reduced ability to correct the bleeding time defect in von Willebrand's disease and to have abnormal mobility of their VIIIR:Ag on crossed immunoelectrophoresis. This report concerns the partial characterization of a fragment of VIIIR:Ag that lacks some of the normal antigenic determinants present on VIIIR:Ag. It is present in commercial factor VIII concentrates, but not in cryoprecipitate, and is recovered from the plasma of hemophilic patients who have been infused with these concentrates. The fragment is also produced during disseminated intravascular coagulation. Although it has a similar mobility on SDS agarose electrophoresis to the smallest multimer of VIIIR:Ag, they are not immunologically identical.

Chemical Fractionation↗
PubMed1982

A variant of von Willebrand's disease with abnormal expression of factor VIII procoagulant activity.

Reports on variants of von Willebrand's disease are numerous, but many of these are based on tests that will show marked fluctuations with time and tests that might not be similar in affected family members. This report describes 8 patients with a new variant of von Willebrand';s disease in which there is a normal APTT, slightly reduced one-stage factor VIII:C assay (VIII:C-1), and a drastically reduced two-stage factor VIII:C assay (VIII:C-2). The VIII:C in this variant is more readily adsorbed to AI(OH)3. This variability in VIII:C assays and excessive adsorption to AI(OH)3 are corrected by the addition of either hemophilic plasma or hemophilic factor-VIII-related antigen. This variant is stable with restudy on multiple occasions and is inherited in a stable fashion in three generations of one family. The multimeric structure of the VIIIR:Ag appears normal, although the concentration is moderately reduced. The differences in functional activity, the adsorption to AI(OH)3, and the differences between functional and antigenic (VIII:C Ag) assays of VIII:C support that this is a functional abnormality of type I von Willebrand's disease.

Adult↗
PubMed1982

Cisplatin vestibular ototoxicity: preliminary report.

Sixteen patients were monitored for vestibular ototoxicity while receiving cisplatin in dosages of 180 mg/M2. The incidence of preexisting vestibular functional abnormalities (31%) was higher than the incidence of ototoxicity (18%). Although the number of patients was not large enough for meaningful statistical comparison, the incidence of vestibular ototoxicity from cisplatin was low for the dosage levels employed. Based upon the results of this study, the following recommendations are made for monitoring cisplatin vestibular ototoxicity. 1. All patients should receive vestibular tests prior to cisplatin administration. 2. Subjects, who have reduced (or asymmetric) vestibular function upon pretherapy testing, should be monitored at least weekly for any change in function while receiving cisplatin. 3. Subjects who are normal prior to therapy need to be tested only when cumulative doses exceed 400 mg. The severe nausea and vomiting associated with cisplatin chemotherapy is not related to vestibular ototoxicity.

Adult↗
PubMed1981

Irreversible inactivation of yeast glucose-6-P dehydrogenase by penicillin G.

Yeast glucose-6-P dehydrogenase is irreversibly inactivated by penicillin G. Kinetic data show that 1 molecule of penicillin G reacts with each active unit when the enzyme is inactivated. The rate of inactivation increases greatly with increasing pH. This irreversible inactivation by penicillin G is largely prevented by pyridoxal-P, a reversible inactivator or this enzyme. Prior treatment of penicillin G with penicillinase totally abolishes its ability to inactivate the enzyme.

Dose-Response Relationship, Drug↗
PubMed1981

A subset of human cells isolated and characterized by monoclonal antibodies.

Monoclonal antibodies were induced against leukemic T cells from a patient with chronic lymphocytic leukemia exhibiting natural killer (NK) activity. Two antibodies, termed T811 and M522, reacted by indirect immunofluorescence with distinct sub-populations of normal human mononuclear blood cells. The antibody T811 defines a surface antigen which is restricted to a subset of the T cell lineage. The antigen recognized by the second antibody, M522, is expressed on monocytes and polymorphonuclear leukocytes and, in addition, on 9-17% of nonadherent peripheral blood leukocytes (NAL). It is shown that the total NK activity of NAL is confined to the subset of cells expressing the M522-defined antigen. Moreover, the portion of NK cytotoxicity associated with T lymphocytes is mediated by a subpopulation which is characterized by the simultaneous expression of the T811- and the M522-defined antigens. This population comprises about 4% of NAL and could be isolated to a purity of greater than 85%.

Animals↗
PubMed1981

Synthesis and antimalarial effects of N2-aryl-N4-[(dialkylamino)alkyl]- and N4-aryl-N2-[(dialkylamino)alkyl]-2,4-quinazolinediamines.

A series of N2(and N4)-aryl-N4(and N2)-[(dialkylamino)alkyl]-2,4-quinazolinediamines has been synthesized for antimalarial evaluation. Condensation of the appropriate 2,4-dichloroquinazoline (IV) with the requisite N,N-dialkylalkylenediamine afforded a series of 2-chloro-N-[(dialkylamino)alkyl]-4-quinazolinamines (V) which were condensed with the appropriate arylamine to provide the corresponding N2-aryl-N4-[(dialkylamino)alkyl]-2,4-quinazolinediamines (VI). Hydrolysis of 2,4-dichloroquinazoline to 2-chloro-4-quinazolinol was followed by condensation with the appropriate N,N-dialkylalkylenediamine to give an array of 2-[[(dialkylamino)alkyl]amino]-4-quinazolinols (IXa). Chlorination with phosphorus oxychloride and condensation with a requisite arylamine provided the N2-[(dialkylamino)alkyl]-N4-phenyl-2,4-quinazolinediamines (X). Antimalarial activity was general among the N2-aryl-N4-[(dialkylamino)alkyl]-2,4-quinazolinediamines (VI), while the reverse isomers were of lower activity. Phototoxic liability precluded clinical evaluation of a member of the series.

Animals↗