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Biomedical subjects

J R Johnson

Publications and source records attributed to J R Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1995

Idiopathic juvenile osteoporosis. An unusual cause of back pain in an adolescent.

Idiopathic juvenile osteoporosis represents a rare bone disorder that affects prepubescent children of both sexes. The diagnosis is generally one of exclusion, ruling out other potential metabolic bone diseases. Here, the authors present a representative case of this rare disorder in an otherwise healthy male, along with the clinical history, physical presentation, and review of the available literature. Finally, it is important to note that patients with this disorder often have profound involvement of the spinal column with multiple compression fractures.

Adolescent↗
PubMed1994

Non-exponential behavior of the nuclear magnetization in H-doped copper oxides.

Measurement of the spin lattice relaxation time in H-doped Y2BaCuO5 and YBa2Cu3O6 has revealed a power law growth of the nuclear magnetization M for short times following a saturation pulse sequence. Preliminary experimental results yield exponents of 1/2 and 1/3, depending on the amount of hydrogen present in the sample. We extend Blumberg's theory for relaxation due to paramagnetic centers via dipole-dipole interaction in the absence of spin diffusion to obtain M approximately tD/6 where D is the dimensionality of the system. This yields exponents of 1/2 and 1/3 for three- and two-dimensional systems, respectively. At long times the magnetization growth becomes exponential.

Copper↗
PubMed1994

No gioke intended.

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Neisseria meningitidis↗
PubMed1994

O, K, and H antigens predict virulence factors, carboxylesterase B pattern, antimicrobial resistance, and host compromise among Escherichia coli strains causing urosepsis.

The O:K:H serotypes of 75 Escherichia coli blood isolates from patients with urosepsis were compared for the presence and expression of determinants for P fimbriae, hemolysin, and aerobactin; antimicrobial resistance; the carboxylesterase B phenotype; and associated compromising host conditions. O groups, K types, and O:K:H serotypes previously associated with urovirulence accounted for 69%, 60%, and 31% of the population, respectively. Chromosomal determinants for P fimbriae, hemolysin, and aerobactin were present in combination more commonly among strains belonging to urovirulence-associated O groups, K types, and O:K:H serotypes. Similarly, antimicrobial resistance was strikingly less prevalent, the B2 carboxylesterase phenotype more common, and associated host compromise less common among such strains. These data demonstrate that the O groups, K types, and O:K:H serotypes traditionally associated with urovirulence are prominent among E. coli strains causing urosepsis, in which they are associated with presence and expression of multiple chromosomal virulence factor determinants, susceptibility to antimicrobial agents, the B2 carboxylesterase phenotype, and noncompromised hosts.

Antigens, Bacterial↗
PubMed1994

Pigeon and dove eggwhite protect mice against renal infection due to P fimbriated Escherichia coli.

Pigeon and dove eggwhite exhibit high level P1 antigenic activity and are potent and specific inhibitors of adherence mediated by P fimbriae of uropathogenic Escherichia coli. To evaluate pigeon and dove eggwhite as P fimbrial receptor analogues in the prevention of ascending renal infection, mice were challenged with a P fimbriated E. coli urosepsis isolate suspended in saline alone or in saline plus various inhibitors of adherence, including D-mannose, globoside, and chicken, dove, and pigeon eggwhite. D-mannose inhibited mannose-sensitive adherence but not P fimbrial adherence, and failed to prevent renal infection. Globoside and chicken eggwhite also failed to inhibit P fimbrial adherence; chicken eggwhite had little and globoside had no impact on renal infection. In contrast, dove and pigeon eggwhite eliminated P fimbrial adherence and significantly reduced the incidence and intensity of renal infection. These findings suggest that pigeon and dove eggwhite provide P1-antigen-specific protection against ascending renal infection in mice due to P fimbriated uropathogenic E. coli.

Aged↗
PubMed1994

Differential induction of mRNAs for the glycolytic and ethanolic fermentative pathways by hypoxia and anoxia in maize seedlings.

Fructose-1,6-biphosphate aldolase (ALD) and enolase (ENO) from the glycolytic pathway and pyruvate decarboxylase (PDC) and alcohol dehydrogenase 2 (ADH2) from the ethanolic fermentative pathway, are enzymes previously identified as among those synthesized selectively in O2-deficient roots of maize (Zea mays L.). The present study measured levels of transcripts representing these two pathways in 5-mm root tips, root axes (the remainder of the primary seminal root), and shoots of maize seedlings to determine how closely both pathways were co-induced and how they were modulated by changes in O2 concentration. In hypoxic seedlings with the roots in solution sparged with 5% (v/v) O2 (balance N2) and the shoots in the same gaseous atmosphere, mRNAs for Pdc1 and Adh2 in root tips both increased about 15-fold during the first 12 h, followed by a decline toward initial levels by 18 to 24h. Message levels for Ald1 and Eno1 showed only small changes during hypoxia. When expression was examined under anoxia, the extent to which all four mRNAs increased in different tissues depended on whether the seedlings had been previously acclimated to hypoxia or were anoxically shocked. The results show that although all the genes examined increased expression during hypoxia and/or anoxia, they differed in the rapidity and magnitude of the response and in the time to reach maximal message levels: there was no common pattern of change of message levels for the glycolytic or for the fermantative enzymes.

Alcohol Dehydrogenase↗
PubMed1994

Factors associated with risk for HIV infection among chronic mentally ill adults.

OBJECTIVE: Chronic mentally ill adults have been found to be at risk for HIV infection. The authors investigated the prevalence of HIV risk behaviors among psychiatric outpatients. Correlates of HIV risk factors and characteristics of patient relationships in which risk occurred were investigated. METHOD: Structured interviews were conducted with 95 chronic mentally ill adults from urban community support service programs. The interviews focused on sexual and substance use behavior, history of HIV risk behaviors, and relationship characteristics related to risk. RESULTS: The study showed that 27% of all patients had had two or more sex partners in the previous year and 18% had received money or drugs for sex. High rates of illicit drug use were also found, with frequent use of drugs or alcohol in association with sexual activity. Multiple regression analyses showed that use of illicit drugs, meeting sex partners in psychiatric clinics, and meeting partners in bars accounted for a substantial proportion of the variance in HIV risk behavior. CONCLUSIONS: These results suggest an urgent need for HIV prevention programs targeted at urban chronic mentally ill adults. Risk-producing characteristics of patient relationships and social networks should be addressed in the development of prevention interventions.

Adult↗
PubMed1994

The efficacy of choline magnesium trisalicylate (CMT) in the management of metastatic bone pain: a pilot study.

Twenty-six patients with painful, bony metastases were recruited into a randomized, double-blind, single dose, two-treatment, three-part crossover study of choline magnesium trisalicylate (CMT) and placebo. Assessments were made prior to and at one, two, three and four hours after dosing. Bone pain caused by metastatic cancer was significantly relieved one hour after the administration of 1500 mg CMT (p = 0.04). At all four time points the pain was less than baseline with CMT and at three time points greater than baseline with placebo but these results did not reach statistical significance. The summed pain intensity difference for patients was greater with CMT than with placebo, but this also did not reach significance. The incidence of volunteered side-effects was similar for both treatments. The results suggest that a nonacetylating, nonsteroidal anti-inflammatory drug may have a role complementary to that of an opioid in the management of metastatic bone pain.

Adolescent↗
PubMed1994

Sexual sensation seeking: scale development and predicting AIDS-risk behavior among homosexually active men.

Sensation seeking, the propensity to prefer exciting, optimal, and novel stimulation or arousal, is a potential mediating factor in sexual risk for human immunodeficiency virus infection (HIV), the cause of acquired immunodeficiency syndrome (AIDS). However, the most widely used measure of sensation seeking, the Sensation Seeking Scale (Zuckerman, Kolin, Price, & Zoob, 1964), contains numerous culturally outdated items and items that do not pertain to sexual behavior. In this study, 106 homosexually active men completed newly developed measures of sensation seeking related to sexual and nonsexual experiences, as well as a measure of sexual compulsivity. Results show that the new scales were internally consistent and time-stable. Additional analyses demonstrated convergent, divergent, and discriminant validity for these scales, showing them to be of use as mediating variables in models of high-risk sexual behavior. Implications for HIV prevention and behavior change are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1994

The use of somatosensory evoked potentials to prevent ischemic neural damage during preoperative embolization of a vascular renal metastasis.

Tumors at the spinal cord level present challenging surgical problems. Hypernephromas and other tumors may have copious bleeding at the time of resection. This bleeding can be reduced by preoperative embolization resulting in a dramatic decrease in surgical morbidity. However, embolization does carry a risk of spinal cord infarction and resultant neurologic injury. To monitor this, somatosensory evoked potentials (SSEPs) were evaluated during embolization, with a resultant termination of the procedure after significant SSEP changes and clinical symptoms indicated cord ischemia. The SSEP readings normalized 24 hours later, by the time of surgical resection. We present a relevant case history and review of the literature on this subject. Clearly, SSEPs, and in the future, motor evoked potentials (MEPs), serve as a valuable adjunct to monitoring spinal cord function during embolization and may prevent preoperative ischemic injury.

Aged↗