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Biomedical subjects

E Charney

Publications and source records attributed to E Charney.

At least 55 records · Page 3Linked to original sources
PubMed1983

Electric dichroism of DNA. Influence of the ionic environment on the electric polarizability.

In order to test the diffuse ion atmosphere polarization model recently developed by us, the effects of ionic strength, titrating with Mg2+ and Co(NH3)3+6, and coion charge on the electric polarizability of short fragments of DNA are investigated. The results are consistent with the predictions of the theory and show that the diffuse ion atmosphere polarization contributes significantly to the overall orientation of DNA. At low ionic strengths, we attempt to separate the total dipole moment into two components: one that agrees well with the Debye-Hückel ion atmosphere calculations, while the other, presumably due to condensed counterion polarization, appears to be substantially independent of the ionic strength. At higher salt concentrations, however, a simple separation into dipole components is not possible, perhaps due to a significant coupling of ion flows between the diffuse atmosphere and the condensed counterion layer.

Animals↗
PubMed1983

Urinary tract infection in infants with unexplained fever: a collaborative study.

Nine centers collaborated to determine the rate of urinary tract infection in infants with unexplained fever, to determine whether the rate is higher in febrile infants than in asymptomatic infants, and whether the yield justifies urine cultures in febrile infants. Urine cultures were done in 501 infants 0 to 2 years of age. The rate of confirmed urinary tract infections in the 193 febrile infants was 4.1%. All infections were in girls, with a rate of 7.4%. The rate of confirmed urinary tract infections in the 312 asymptomatic infants was 0.3%; again, all infections were in girls, with a rate of 0.7%. The rate in febrile girls was significantly higher than the rate in asymptomatic girls (P less than 0.01). The data support the advisability of culturing the urine of infant girls with unexplained fever.

Acute Disease↗
PubMed1983

Vesicostomy for neurogenic bladder with spina bifida: followup.

Of 260 patients being actively followed in a myelodysplasia clinic 48 have had a vesicostomy. Vesicostomy was done because of hydroureteronephrosis in 44 cases, infection in 3 and failure of clean intermittent catheterization in 1. Of the 48 patients 16 underwent closure of the vesicostomy, generally between ages 6 and 10 years, an age when the child is prepared to begin clean intermittent catheterization and is motivated to achieve continence. Two children underwent early vesicostomy closure because the bladder emptied adequately and neither has yet begun clean intermittent catheterization. Two children on clean intermittent catheterization are not acceptably continent. The remaining 12 patients are continent for at least 4 hours on clean intermittent catheterization, some with adjuvant drug therapy. No child has exhibited loss of bladder volume while diverted. Vesicostomy offers excellent temporary decompression of the urinary tract in children with spina bifida and neurogenic bladder, and has no long-term harmful effects on the bladder.

Child↗
PubMed1983

Central nervous system lesions and developmental scoliosis in myelomeningocele.

Hydrocephalus, spinal cord tethering, cord atresia, hydromyelia, syringomyelia and various manifestations of the Arnold-Chiari malformation occur in association with scoliosis in patients with myelomeningocele. While the causes of the cord lesions remain debatable, these lesions appear to be progressive and causally related to the scoliotic deformity. We have reviewed seventeen myelomeningocele patients with developmental scoliosis and have found that aggressive orthopaedic treatment combined with neurosurgical treatment can satisfactorily control spinal deformity in most cases. Before undertaking orthopaedic treatment of severe spinal deformities in patients with myelomeningocele a careful investigation of the central nervous system with myelography and cord and head CT scans should be carried out.

Arnold-Chiari Malformation↗
PubMed1983

Referrals from an emergency room to primary care practices at an urban hospital.

Three hundred ninety-eight patients treated in the emergency room for non-urgent complaints who stated that they had no regular source of primary medical care were referred to one of several medical care centers in the area. Overall, 34 per cent of such patients complied with the referral. Correlates of compliance were: age (very young and very old), patient-perceived health status, medically determined need for follow-up care, and having an appointment made by the emergency room provider. Another group of 500 successfully referred patients became excellent users of the primary care office, complying with requested health maintenance and follow-up visits. However, emergency room utilization by the successfully referred patients did not decrease more than among referred patients who did not enroll in the primary care source.

Adolescent↗
PubMed1982

Length changes in solution accompanying the B-Z transition of poly (dG-m5dC) induced by Co(NH3)63+.

Transient electric dichroism measurements have been used to observe the rotational relaxation times of 145 base pair fragments of poly (dGm5dC) and random sequence DNA to solution. From these the lengths of the fragments are calculated and the interbase pair separation or rise per base pair (RPB) calculated. The observations show that even in low salt, the addition of very low concentrations of trivalent Co(NH3)63+ results in a transition of the dGm5dC polymer from B-form to Z-form with a change in the RPB from 3.4 +/- .06A to 3.7 +/- .06A, the latter form defined by the criterion of an inverted circular dichroism spectra similar to that observed at high salt in the absence of Co(NH3)63+. The 145 base pair DNA and poly (dGm5dC) are found to be essentially fully extended rods in low salt (0.2 - 2 mM Na+) solutions.

Base Composition↗
PubMed1982

Electric dichroism of deoxyribonucleic acid in aqueous solutions: electric field dependence.

The ionic strength and molecular weight dependence of the electric field dichroism of DNA, using native and sonicated calf thymus DNA, has been examined in the range of 0.09-1.0 mM NaCl solutions for molecular weights ranging from 1.24 x 10(5) to 44 x 10(5). The application of a classical theoretical analysis implies that the orientation results from an induced moment which appears to saturate at moderate fields of several killivolts per centimeter and that the induced moment is at least partly characteristic of that expected of a polyion whose charge is partially counterion compensated. The orientation leads to dichroism values which are in accord with other observations and are lower than expected for a B-form rod of DNA. These values, however, are not uniquely interpretable as resulting from base tilting.

DNA↗
PubMed1981

Polarization of the ion atmosphere of a charged cylinder.

The dipole moment is calculated for an electric-field-induced polarization of a Debye-Hückel ion atmosphere surrounding a charged rod. If L is the length of a thin rod. Q is its linear charge density, Z is charge of the salt ion in solution, and k is the Debye-Hückel shielding parameter, then for KL less, similar 10, the calculated polarizability is proportional to Z(2)Q(2)L(1.8)/K(1.2). Comparison with experimental data for DNA shows that the ion atmosphere dipole is of the correct magnitude and is consistent with observed variations with Z, Q, L and k.

Journal Article↗
PubMed1981

Pediatrics in the community hospital.

The subject of the community hospital's pediatric service-its mission, organization and staff-is ripe for critical study and innovative implementation. The centripetal force of medical education which has kept the best medical school graduates within the tertiary hospital walls during medical school, residency, fellowship, and subspecialty practice has had a perhaps unintended though real inhibiting effect on the community hospital. Those who practice in the community environment may well be less equipped to study and change their world than are their academic counterparts. They often lack the training to do so, and lack time that can be taken from busy practice commitments. Those most capable of critical study are unfamiliar with or at least not always empathic to the community's problems. We suggest that there are many clinical questions and many organizational issues that are legitimate matter for study within community hospitals, in which a majority of the nation's children are cared for. The increasing number of affiliations between university and community hospitals may allow a true academic bond to develop and learning to occur at both ends. The community hospital has both the need and potential for important growth in the 1980s.

Allied Health Personnel↗
PubMed1980

Orientation of the nucleosome within the higher order structure of chromatin.

We have used electric dichroism to investigate chromatin fragments isolated from chicken erythrocytes. Both within the extended "10 nm filament" present at low salt and the condensed "30 nm solenoid" induced by the addition of divalent cations, the data give a quantitative description of the DNA conformation in the higher order structure of chromatin. In the 10 nm filament both the spacer DNA and the flat faces of the core particle discs must be oriented within 20 degrees of the fiber axis. Within the Mg++-induced 30 nm solenoid the flat faces of the core particles must also be oriented close to parallel to the solenoid axis, the estimated angle depending upon the disposition of the spacer DNA. We suggest a model for the 30 nm solenoid.

Animals↗
PubMed1980

The role of the ionic environment in the orientation of nucleic acids in electric fields.

The relationship between polyelectrolyte theories based on linear charge density models and the electric-field induced orientation of the polyelectrolytes, poly(A), poly(C) and DNA is examined by varying their ionic environment with respect to ionic strength and acidity. The degree of counterion condensation on the polyelectrolytes predicted by the theories of Manning and Record is shown to be related linearly to the orientation as measured by their dichroism in the field. Micro-structural differences between poly(A) and poly(C) account for the differences in their dependence on the pH of the medium which affects the counterion condensation and thus the polarization in the orienting electric fields. The results consequently support recent treatments of linear polyelectrolytes having a high charge density which model them as smoothly charged linear polyions, but indicate that these models are insufficient to account for some of the effects of microstructural variations.

Journal Article↗
PubMed1980

Ionic strength and counterion repulsion as factors in the behavior of polyions in orienting electric fields.

The effect of counterion-counterion repulsion on the orientation of DNA, a polyion of high charge density is examined by electric-field orientation experiments. The charge species of the counterion and the ionic strength effect the orientation in a manner consistent with a theoretical treatment of the polarization of high charge density polyelectrolytes in terms of the effect of the applied field on the equilibrium distribution of condensed counterfoils on the polyion.

Journal Article↗
PubMed1980

Increased lead absorption in inner city children: where does the lead come from?

Pica for lead-containing paint has been questioned as the principal mechanism for the widespread moderately elevated blood lead levels (30 to 80 microgram/100 ml) in inner city children. This study explored the hypothesis that lead-contaminated household dust is a major source of lead for these children; hand contamination and repetitive mouthing is the proposed mechanism of ingestion. Forty-nine inner city children with blood lead 40 to 70 microgram/100 ml were matched with 50 children with blood lead less than or equal to 29 microgram/100 ml from the same inner city environment. House dust lead and lead on hands were found in significantly greater quantity among experimental subjects. Other factors differed between groups; lead content of peeling paint, soil lead, and pica affected more experimental than control children, but did not account for more than 50% of experimental cases. The cause of moderate blood lead elevation is multifactoral: no single source accounted for all children with elevated levels. However, lead contamination of house dust and hands appears to be a major factor in this condition.

Child, Preschool↗