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Biomedical subjects

J Miller

Publications and source records attributed to J Miller.

At least 595 records · Page 33Linked to original sources
PubMed1993

Vancomycin skin tests and prediction of "red man syndrome" in healthy volunteers.

The purpose of the present study was to assess the cutaneous response to intradermally administered vancomycin in healthy adults and to determine whether the magnitude of the cutaneous response correlated to the severity of "red man syndrome" (RMS) following intravenous administration of vancomycin to the same subjects. Eleven healthy males were skin tested with intradermally administered histamine and saline controls and intradermally administered vancomycin at different concentrations. Vancomycin caused a dose-dependent area of flare in all subjects. The sigmoidal maximal flare model was used to fit each dose-response curve, and cutaneous responsiveness to vancomycin was quantified by various methods, including the flare area at each dose, maximum flare area (maximal flare), dose required to produce 50% of maximum flare, dose required to produce a flare area of 400 mm2, and the slope of the dose-response curve. One week after skin testing, subjects received an infusion of vancomycin, 15 mg/kg of body weight over 60 min. For the assessment of the severity of RMS, we used previously described methods. Although all subjects experienced erythema from the intravenously administered vancomycin and 10 subjects had pruritus, there was no significant correlation between vancomycin skin test results and the severity of RMS. We conclude that vancomycin skin tests do not predict the severity of RMS. In addition, vancomycin skin tests may be of no benefit for assessing immunoglobulin E-mediated allergy to vancomycin, since all subjects had a positive reaction at concentrations of > or = 10 micrograms/ml.

Adult↗
PubMed1993

The effects on rat thyroid function of an hepatic microsomal enzyme inducer.

1. Following daily administration to male albino rats for 2 weeks, beta-naphthoflavone (25 and 60 mg kg-1, i.p.) and phenobarbitone (100 mg kg-1, p.o.) produced their characteristic patterns of induction of P450-related enzyme activities. beta-naphthoflavone also induced p-nitrophenol glucuronidation by 160% over controls, while phenobarbitone produced only a 45% induction of this conjugation activity. 2. beta-Naphthoflavone produced significant reductions in plasma thyroxine (T4) concentrations on days 4 and 16 and also decreased tri-iodothyronine (T3) on day 4. Thyroid-stimulating hormone (TSH) was significantly increased on day 16 by the higher dose of beta-naphthoflavone. Thyroid weight was significantly increased at both dose levels on day 16 and liver weight was significantly increased on both days 4 and 16. No histopathological changes were seen in the liver or pituitary, but 30% of the animals showed minimal to mild follicular epithelial hypertrophy of the thyroid gland. 3. Phenobarbitone had no effect on T4 concentrations, but significantly decreased T3 on day 4. TSH increased by 60% on day 16, but was not statistically significantly compared with controls. Thyroid weight was significantly increased on day 16 and liver weight was significantly increased on days 4 and 16. Mild to moderate thyroid follicular epithelial hypertrophy and moderate hepatocyte hypertrophy occurred in all animals. No histopathological changes were seen in the pituitary. 4. The early changes in T4 and/or T3 were probably due to increased hepatic clearance by induction of thyroxine glucuronidation with both compounds. Thyroid hypertrophy would be expected to follow as a result of activation of the hypothalamic-pituitary-thyroid axis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Human immunodeficiency virus-related headache.

We retrospectively assessed the frequency and clinical characteristics of headache occurring in human immunodeficiency virus (HIV)-infected patients in whom we had excluded all other causes, and determined the frequency of a similar headache in an HIV-negative group. Over a 1-year period, the HIV-related headache occurred in 2.8% of total admissions to the HIV service as opposed to 0.2% of admissions to the neurology service. The affected patients had advanced HIV infection (CD4+ cell count = 58.9 +/- 80.3; normal, > 500 x 10(-6)/l). The headache had features similar to those ascribed to HIV aseptic meningitis and was not related to the presence of AIDS dementia complex or its subsequent development over a 6-month follow-up. We propose that this is a distinct clinical entity related to HIV infection that is similar, if not identical, to HIV aseptic meningitis except for the lack of a CSF pleocytosis, probably reflecting the lymphocyte depletion that is characteristic of the more advanced state of HIV infection.

AIDS Dementia Complex↗
PubMed1993

Redundancy gains and coactivation with two different targets: the problem of target preferences and the effects of display frequency.

When a visual display contains two targets, both of which require the same response, reaction times (RTs) are faster than when only one target appears. This effect has previously been obtained regardless of whether the redundant targets are the same or different in shape, and in at least one set of two-target experiments, the redundancy gains have been larger for different targets (Grice & Reed, 1992). Experiments with two different targets have also revealed violations of the race-model inequality, suggesting that redundant targets coactivate the response (Miller, 1982). The present paper reexamines both of these findings, because both appear to be inconsistent with the interactive race model (Mordkoff & Yantis, 1991). Experiment 1 shows that the race-model inequality is not violated when the experimental design is free of biased contingencies; Experiment 1 also provides evidence that target preferences may artifactually produce the RT advantage for different- over same-target trials. Experiment 2, however, shows that the race-model inequality is violated when the frequencies of single- and redundant-target displays are equated (without introducing any biased contingencies), implying that the interactive race model cannot account for the results of experiments involving more than one type of target. Alternative loci for coactivation are briefly discussed.

Adult↗
PubMed1993

Options for small employers.

Although offering health benefits is very expensive, many employers (small, medium, and large) make health care purchasing decisions based on very little information. This is largely because employers have not taken the time to learn how to be knowledgeable health care purchasers. Higher health care costs result when employers: purchase programs and services that employees and their dependents do not need and seldom use; pay (unknowingly) for services not offered in their benefit plan; accept and pay for ineffective cost containment programs that increase (not decrease) health care costs (remember that cost containment is a business in itself); make standard recommended changes (e.g., increased copays or deductibles) to their benefit plans, hoping to reduce costs (the result has been higher costs for too many employees); fail to assess whether health plans and insurance companies have effective internal quality and cost management programs; use financial incentives to encourage employees and dependents to enroll in managed care plans without examining whether the health plan or insurer used quality criteria, high standards, and capable processes in developing provider networks. (Capable processes consistently deliver quality products or services.) Most health plans and insurance companies have chosen providers based on their willingness to discount their charges, which places all parties (health plans or insurance companies, employers, and patients) at risk. Most of the problems listed above could be avoided if small employers based their health care purchasing decisions on information obtained from a careful analysis of needs and expectations.(ABSTRACT TRUNCATED AT 250 WORDS)

Administrative Personnel↗
PubMed1993

Brain-derived neurotrophic factor (BDNF) prevents the degeneration of medial septal cholinergic neurons following fimbria transection.

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, supports the survival of developing basal forebrain cholinergic neurons in vitro and is retrogradely transported by cholinergic neurons of the medial septum and diagonal band following intrahippocampal injections in vivo. To substantiate a potential role for BDNF in the maintenance of forebrain cholinergic neurons in the adult brain, we assessed the ability of BDNF to sustain the phenotype of medial septal cholinergic neurons following a unilateral transection of the fimbria. BDNF, NGF, or vehicle solutions were infused continuously in adult female rats either into the lateral ventricle (intracerebroventricularly) or directly into the septum for 2 weeks beginning at the time of the transection. In vehicle-infused animals, only 28% of the ChAT-immunoreactive neurons remained on the side ipsilateral to the lesion compared to the contralateral intact side. When infused intracerebroventricularly, both BDNF and NGF reduced the extent of the phenotypic loss, in that 44% and 68%, respectively, of the ChAT-immunopositive neurons remained on the lesioned side. Intraseptal infusion proved even more effective, in that following BDNF and NGF treatment 60% and 86%, respectively, of the normal complement of ChAT-immunopositive neurons were apparent on the side ipsilateral to the lesion. Similar results were obtained when an antibody to the low-affinity NGF receptor was used to identify the cholinergic neurons. To determine if the apparent greater efficacy of NGF compared to BDNF might be related to differences in delivery, we examined the patterns of distribution of radiolabeled BDNF and NGF injected into the lateral ventricle. 125I-BDNF showed only very little diffusion from the ventricles into the adjacent neural tissue and negligible retrograde labeling of the neurons within the basal forebrain. 125I-NGF, however, diffused readily into the brain, resulting in widespread retrograde labeling of basal forebrain neurons. A similarly limited distribution pattern was observed where BDNF was detected immunohistochemically in animals infused intracerebroventricularly (12 micrograms/d) for 2 weeks. In contrast, when delivered intraseptally, the same dose of BDNF exhibited a widespread diffusion within the surrounding neuropil and retrograde labeling of neurons in the medial septum and the vertical limb of the diagonal band. Thus, when delivered effectively, BDNF has a substantial capacity to rescue axotomized cholinergic neurons.

Animals↗
PubMed1993

The fragmentation of 670A MeV neon-20 as a function of depth in water. III. Analytical multigeneration transport theory.

This is the final report of a detailed study of the interaction of 670A MeV neon ions with water, used as a presumed tissue-equivalent target. A first comparison of the data with theoretical fluence spectra predicted by the one-generation heavy-ion transport code HZESEC was reported previously. In the present article, subsequent nuclear interactions of the fragment are taken into account, using the LBLBEAM multigeneration heavy-ion transport code, which incorporated new features and modifications intended to address some of the approximations made in the previous calculation. The LBLBEAM code uses the method of characteristics and an iterative procedure to solve a one-dimensional Boltzmann transport equation for the first through third successive generations of nuclear reaction products; it includes a recent version of the semiempirical model used to derive nuclear interaction cross sections. The stopping power used for the theory was calculated in the same way that experimental time-of-flight and energy-loss data are converted to obtain a comparison independent of stopping power; accordingly, good agreement was found between calculated and measured neon fluence spectra in the Bragg peak region. Multiple scattering effects were considered separately for each isotope in the present work. Acceptance factors were calculated as previously, assuming that all projectile fragments originate from the first nuclear interaction. The results show that lower-mass isotopes can account for the high-LET portions of the spectrum in measured fluence spectra. Third-generation products become increasingly important as a source of lighter fragments for depths comparable with the primary particle mean free path, accounting for between one-third and one-half of carbon and lighter particles near the Bragg peak; higher-order interactions were negligible for the detector geometry and material thicknesses examined. Agreement between measured and calculated fluence spectra is 30% (20% for integral fluences). Inclusion of hydrogen, helium, and lithium fragments improves agreement between calculated and measured RBE values for spermatogonial cell survival, but tertiary particle acceptance and track structure effects need to be understood in greater detail to predict RBE accurately.

Energy Transfer↗
PubMed1993

Preoperative prediction for the use of cardiopulmonary bypass in lung transplantation.

Cardiopulmonary bypass has been widely used in the management of isolated single and double lung transplantations. Although there are certain clear-cut preoperative indications for cardiopulmonary bypass, in many patients the decision to use this modality is based on the hemodynamic consequences of intraoperative pulmonary artery clamping. We have performed 109 isolated lung transplantations. In 69 patients (38 single lung transplantations and 31 double lung transplantations) cardiopulmonary bypass was initiated only on the basis of intraoperative hemodynamics. We have analyzed preoperative data from these 69 patients to determine whether an intraoperative requirement for cardiopulmonary bypass can be predicted. Of 38 single lung transplantations, 12 necessitated cardiopulmonary bypass (all patients had restrictive lung disease). No patients with obstructive lung disease who underwent single lung transplantation required cardiopulmonary bypass (p < 0.001). For single lung transplantations, 6-minute walk, the arterial desaturation/oxygen requirements on exercise, and the right ventricular ejection fraction were all significantly different between the cardiopulmonary bypass and noncardiopulmonary bypass groups (p < 0.001). Of 31 double lung transplantations, 10 patients required cardiopulmonary bypass (seven had bronchiectasis, two had obstructive lung disease, and one had restrictive lung disease). For obstructive lung disease, no preoperative parameters predicted cardiopulmonary bypass. In conclusion, cardiopulmonary bypass is not necessary for most patients undergoing lung transplantation (in the absence of an absolute preoperative indication). Obstructive lung disease rarely necessitates cardiopulmonary bypass. In single lung transplantations, the subsequent requirement for cardiopulmonary bypass can be predicted from preoperative cardiopulmonary performance. For double lung transplantations, the requirement for cardiopulmonary bypass is usually dependent on unpredictable intraoperative factors.

Adolescent↗
PubMed1993

Apexification.

Explore the source record for details and available documents.

Apicoectomy↗
PubMed1992

The importance of arginine 102 for the substrate specificity of Escherichia coli malate dehydrogenase.

The malate dehydrogenase from Escherichia coli has been specifically altered at a single amino acid residue by using site-directed mutagenesis. The conserved Arg residue at amino acid position 102 in the putative substrate binding site was replaced with a Gln residue. The result was the loss of the high degree of specificity for oxaloacetate. The difference in relative binding energy for oxaloacetate amounted to about 7 kcal/mol and a difference in specificity between oxaloacetate and pyruvate of 8 orders of magnitude between the wild-type and mutant enzymes. These differences may be explained by the large hydration potential of Arg and the formation of a salt bridge with a carboxylate group of oxaloacetate.

Amino Acid Sequence↗