Broad-spectrum antibiotics in ORACLE.
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Anti-Bacterial Agents↗
Biomedical subjects
C R Martin
Publications and source records attributed to C R Martin.
pH-switchable, ion-permselective gold nanotubule membrane based on chemisorbed cysteine.
An electroless gold plating method was used to deposit Au nanotubules within the pores of a polycarbonate template membrane. pH-switchable ion-transport selectivity was introduced by chemisorbing L-cysteine to the inside tubule walls. At low pH, where both the amino and carboxyl groups of the cysteine are protonated, these membranes preferentially reject cations and transport anions. At high pH, where both the amino and carboxyl groups are deprotonated, these membranes preferentially reject anions and transport cations. At pH = 6.0, near the isoelectric point of the chemisorbed cysteine, these membranes show neither cation nor anion transport selectivity. In addition to this electrostatically based selectivity, because of the small inside diameter of the Au nanotubules (as small as 0.9 nm), these membranes show molecular-size-based selectivity.
Journal Article↗
Growth-restricted premature infants are at increased risk for low thyroxine.
OBJECTIVE: To evaluate, in extremely premature infants, the relationship between growth restriction and early total thyroxine levels, and to determine how maternal, prenatal, perinatal and neonatal variables influence the relationship. STUDY DESIGN: 719 infants born at four medical centers in Massachusetts, New York and New Jersey between 1991 and 1993 were studied. Entry criteria included: gestational age 23--30 weeks, birth weight 500--1500 g, and a serum thyroxine level obtained in the first week of life. Infants born to mothers with a history of thyroid disease were excluded. Birth weight and total thyroxine level are expressed as z-scores (standard deviation units) to adjust for their relationship to gestational age. RESULTS: In linear regression analysis, there was a 0.18 decrease in the total thyroxine z-score for each 1.0 (1 standard deviation unit) decrease in birth weight z-score (p=0.0001). Adjustment for multiple potential maternal, prenatal, perinatal and neonatal confounders failed to identify a factor or factors that could account for the observed association. CONCLUSIONS: The early total thyroxine level in extremely preterm infants was significantly associated with birth weight z-score. This relationship persisted even after adjustment for maternal, prenatal, perinatal and neonatal confounders suggesting antenatal influences. Of clinical importance, growth-restricted infants are at increased risk for early hypothyroxinemia and, possibly, to its related morbidities.
Adult↗
A pilot investigation of the effect of tryptophan manipulation on the affective state of male chronic alcoholics.
A pilot study was conducted to investigate the hypothesis that dietary tryptophan manipulation would influence self-report affective status in alcoholic males. No significant effect of dietary manipulation was observed on the tryptophan/large neutral amino acids ratio or psychological indices of affect. The notion that dietary manipulation may be utilized in improving mood state in alcoholic males was not supported.
Adult↗
Highly sensitive methods for electroanalytical chemistry based on nanotubule membranes.
Two new methods of electroanalysis are described. These methods are based on membranes containing monodisperse Au nanotubules with inside diameters approaching molecular dimensions. In one method, the analyte species is detected by measuring the change in trans-membrane current when the analyte is added to the nanotubule-based cell. The second method entails the use of a concentration cell based on the nanotubule membrane. In this case, the change in membrane potential is used to detect the analyte. Detection limits as low as 10(-11) M have been achieved. Hence, these methods compete with even the most sensitive of modern analytical methodologies. In addition, excellent molecular-sized-based selectivity is observed.
Electrochemistry↗
New developments in membrane-based separations.
Recent advances in membrane-based separations include chiral separations, nanofiltration, ion-permselectivity, gas separation and pervaporation. Novel chiral separations using enzymes and chiral surfactants as carrier have been achieved using facilitated-transport membranes. Graft-copolymeric membranes have been constructed that possess pH-controlled ion selectivity, and membranes have been made from gold nanotubules that exhibit electrochemically controlled permselectivity.
Chemistry Techniques, Analytical↗
Phasic influences on psychometric measures during the menstrual cycle: implications for the construct integrity of the locus of control dimension.
Thirty healthy female volunteers with normal menstrual cycles participated in a study to examine the influence of menstrual cycle phase on locus of control (LC) orientation. LC measures were taken on the follicular, luteal and premenstrual phase of the cycle. It was found that menstrual cycle phase had little effect on LC orientation suggesting that previously observed LC differences across the cycle in dysmenorrhea and premenstrual syndrome sufferers cannot be generalized to a normal non-clinical population. Surprisingly, it was further found that no significant statistical relationship was found between the two LC measures used, in spite of the finding that, individually, each LC measure intercorrelated highly significantly across the menstrual cycle. Since one of the LC scales was derived theoretically, and the other LC scale used was derived from clinical practice, the findings are discussed in relation to the theory-practice divide and the prima facie value of self-report LC measures.
Adult↗
A randomized trial comparing Arglaes (a transparent dressing containing silver ions) to Tegaderm (a transparent polyurethane dressing) for dressing peripheral arterial catheters and central vascular catheters.
The purpose of this trial was to prepare for a large randomized trial comparing Arglaes film dressing, a recent innovation containing silver ions, against Tegaderm, a transparent polyurethane dressing. Thirty-one patients admitted to the intensive care unit and requiring the insertion of an arterial line or central venous catheter were recruited into the study. Skin swabs were taken from the insertion sites prior to catheterization and on removal of the intravascular device to measure skin colonization rate between the two dressings. The catheter tips were also cultured on removal to establish if there was a difference between the two groups. No statistical differences were found in bacterial growth between the two dressings.
Adolescent↗
Relation of traditional risk factors to intrauterine growth retardation among United States-born and foreign-born Mexican Americans in Chicago.
OBJECTIVES: To determine the relation of traditional sociodemographic characteristics to the small-for-gestational age rates of urban Mexican Americans. DESIGN: A cross-sectional study. METHODS: We performed a stratified analysis of 1982-1983 Illinois vital records and 1980 U.S. Census income data. The authors analyzed the 1982-1983 Illinois vital records and 1980 U.S. Census income data to determine whether maternal sociodemographic characteristics are associated with the small-for-gestational age (weight-for-gestational-length < 10th percentile) rates among Mexican Americans in Chicago. RESULTS: The small-for-gestational age rate was 2.1% for infants with U.S.-born mothers (N = 2,253) compared to 1.4% for infants with foreign-born mothers (N = 8,746); relative risk 1.5 (95% confidence interval 1.1-2.1). For the U.S.-born cohort, maternal education, marital status, parity, prenatal care, and community income were associated with small-for-gestational age rates. In contrast, with the exception of marital status, these commonly cited risk factors were not associated with the small-for-gestational age rates of infants with Mexican-born mothers. The U.S.-born:Mexico-born small-for-gestational age rate ratio fluctuated around 2 among mothers with a high-risk (maternal age < 20 years, < 12 years education, unmarried marital status) demographic profile. CONCLUSIONS: We conclude that traditional sociodemographic risk factors have different reproductive outcome consequences for U.S.-born and foreign-born Mexican-American mothers.
Adolescent↗
Enantioseparation using apoenzymes immobilized in a porous polymeric membrane.
Chemical separations represent a large portion of the cost of bringing any new pharmaceutical product to the market. Membrane-based separation technologies, in which the target molecule is selectively extracted and transported across a membrane, are potentially more economical and easier to implement than competing separations methods; but membranes with higher transport selectivities are required. Here we describe an approach for preparing highly selective membranes which involves immobilizing apoenzymes within a microporous composite. The apoenzyme selectively recognizes its substrate molecule and transports it across the composite membrane, without effecting the unwanted chemical conversion of the substrate molecule to product. We demonstrate this approach using three different apoenzymes. Most importantly, it can be used to make enantioselective membranes for chiral separations, one of the most challenging and important problems in bioseparations technology. We are able to achieve a fivefold difference between the transport rates of D- and L-amino acids.
Alcohol Dehydrogenase↗
Prediction of relapse after treatment of coccidioidomycosis.
Relapse after apparently successful treatment of coccidioidomycosis has been a problem with both amphotericin B and the azoles. We conducted a retrospective cohort study of 34 patients who required therapy for coccidioidomycosis between 1973 and 1993; 10 relapsed and 25 (one patient received two courses of therapy) did not relapse during follow-up. The mean time to relapse after completion of therapy was 7.3 months (range, 1-21 months). All 34 patients responded clinically to therapy. A fourfold or greater decrease in titers of antibody, as determined by complement fixation (CF), during therapy was seen in seven (78%) of nine patients who relapsed and 17 (85%) of 20 patients who did not relapse (P = .956). There was no significant difference between relapsers and nonrelapsers in terms of the lowest CF titer during therapy, the CF titer at the end of therapy, or the peak CF titer. The risk of relapse was increased among those with a peak CF titer of > or = 1:256 (relative risk [RR] = 4.7; 95% confidence interval [CI] = 1.4-16.1), as compared with patients who did not mount such a high antibody response. Similarly, the risk of relapse was higher among those with serially negative coccidioidin skin tests (CSTs) than those with serially positive CSTs (RR = 4.8; 95% CI = 1.2-19.5). We conclude that clinical response, lowest CF titer, end-of-therapy CF titer, and decrease in the CF titer of at least fourfold are not predictive of relapse in patients with coccidioidomycosis. Negative serial coccidioidin skin tests and a peak CF antibody titer of > or = 1:256 are independently associated with increased risk of relapse.
Adolescent↗
Isolation and characterization of Ehrlichia chaffeensis strains from patients with fatal ehrlichiosis.
Two new isolates of Ehrlichia chaffeensis (designated Jax and St. Vincent) were obtained from patients with fatal ehrlichial infections. Patients developed characteristic manifestations of severe disease due to E. chaffeensis, including marked thrombocytopenia, pulmonary insufficiency, and encephalopathy. Primary isolation was achieved in DH82 cells; the Jax and St. Vincent isolates were detected within 19 and 8 days postinoculation, respectively. The isolates were characterized by molecular evaluation of the 16S rRNA gene, the groESL heat shock operon, a 120-kDa immunodominant protein gene, and an incompletely characterized repetitive-motif sequence (variable-length PCR target [VLPT]). The sequences were compared with those of the corresponding molecular regions in the type isolate (Arkansas). St. Vincent contained one fewer repeat unit in both the 120-kDa protein gene and the VLPT compared with corresponding sequences of the Jax and Arkansas isolates. 16S rRNA gene sequences from the two new isolates had 100% identity to the corresponding sequences of the 91HE17 and Sapulpa isolates of E. chaffeensis, and to the corrected 16S rRNA gene sequence of the Arkansas isolate. The Jax isolate grew more slowly than the St. Vincent isolate in DH82 cells, and both of the new isolates grew more slowly than the extensively passaged Arkansas isolate. Although specific associations between ehrlichial pathogenicity and genotype were not identified from these comparisons, recovery of this organism from a spectrum of clinical presentations remains an integral step in understanding mechanisms of disease caused by E. chaffeensis.
Analysis of Variance↗
Myocardial infarction in sickle cell disease.
Gross and microscopic findings consistent with acute (three patients) and healed (four patients) myocardial infarction were found in seven (9.7%) of 72 consecutive hearts from patients with sickle cell disease studied after autopsy between 1950 and 1982. Gross obstructive and atherosclerotic lesions were absent in all seven patients, while microthrombi were present in the arterioles of infarcted tissue in two patients. Pathophysiological mechanisms responsible for the infarction are unclear, but anemia, platelet thrombi, coronary vasospasm, and abnormal rheology related to sickle cells may all be important. Chest pain occurred clinically in six of the seven patients and ECG findings typical of infarction were found in two patients. One patient died suddenly. These findings suggest that ischemic heart disease may be present in a significant number of patients with sickle cell disease and should be considered in all patients who complain of chest pain, whether or not the patient is in crisis.
Adult↗
Coccidioidomycosis in California: regional outbreak, global diagnostic challenge.
Beginning in 1991, case reports of coccidioidomycosis in California increased dramatically, pursuant to a variety of natural and demographic factors. This highly infectious fungal disease with propensity to disseminate widely, mimic other conditions, and cause pathology at locations distant in place and time is readily treatable if recognized at an early stage. The concentration of military bases in endemic areas and the mobility of military personnel suggest a heightened potential for case presentations elsewhere and a need for elevated diagnostic suspicion on the part of military physicians worldwide. We review three cases of disseminated disease recently referred to our facility.
Adult↗
Synthesis of polymeric microcapsule arrays and their use for enzyme immobilization.
Current methods for immobilizing enzymes for use in bioreactors and biosensors include adsorption on or covalent attachment to a support, micro-encapsulation, and entrapment within a membrane/film or gel. The ideal immobilization method should employ mild chemical conditions, allow for large quantities of enzyme to be immobilized, provide a large surface area for enzyme-substrate contact within a small total volume, minimize barriers to mass transport of substrate and product, and provide a chemically and mechanically robust system. Here we describe a method for enzyme immobilization that satisfies all of these criteria. We have developed a template-based synthetic method that yields hollow polymeric microcapsules of uniform diameter and length. These microcapsules are arranged in a high-density array in which the individual capsules protrude from a surface like the bristles of a brush. We have developed procedures for filling these microcapsules with high concentrations of enzymes. The enzyme-loaded microcapsule arrays function as enzymatic bioreactors in both aqueous solution and organic solvents.
Alcohol Dehydrogenase↗
Ventilation-perfusion relationships in preterm infants after surfactant treatment.
Arterial-alveolar partial pressure differences for oxygen, carbon dioxide, and nitrogen were measured before and after surfactant replacement therapy on 15 occasions in 14 ventilator-dependent preterm infants with hyaline membrane disease (HMD). Eight treatments resulted in a significant improvement in arterial partial pressure of oxygen (PaO2) 2 hr after treatment; 7 did not. Neither group showed any significant change in arterial-alveolar partial pressure differences for oxygen, nitrogen, and carbon dioxide. This observation suggests that if surfactant replacement therapy produces an improvement in PaO2 it does so by recruitment of atelectatic alveoli with a balanced ventilation/perfusion ratio rather than by redistribution of ventilation within already ventilated alveoli.
Biological Products↗
Structure, function, and regulation of the chalcone synthase.
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Acyltransferases↗
Developmental genetic studies of the moss, Physcomitrella patens.
The development of the haploid gametophyte stage of Physcomitrella patens presents excellent opportunities for the detailed study of plant morphogenesis at the cellular level. The filamentous protonema undergoes a number of developmental transitions that can be observed directly in living material using time-lapse video microscopy and that can be manipulated both by treatment with phytohormones and by environmental stimuli. Mutants affecting these processes can be isolated and can be analysed using conventional as well as parasexual methods. Molecular biological techniques are now being established since these will be essential if the mechanisms that bring about morphogenetic processes are to be understood at the molecular level. A technique for genetic transformation has been devised and is being exploited to attempt to tag developmentally-relevant genes using maize transposons. Changes in gene activity associated with developmental transitions and in response to treatment with phytohormones and environmental stimuli are being studied using cDNA library subtraction techniques. Heterologous genes involved in the control of transcription and of the cell cycle are being used to probe the P. patens genome to identify possible homologues involved in developmental regulation.
Cytokinins↗