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The sites of three [Co(NH3)6]3+ ions bound to the phenylalanine tRNA of yeast have been determined by X-ray diffraction analysis. [Co(NH3)6]3+ binds to purine-purine sequences in yeast tRNA Phe. It is different from the binding fo Co2+, which binds to the base and phosphate of residue G15. There are no direct metal-nucleotide bonds, although hydrogen bonding of the coordinated ammines to double-helical guanylguanosine sequences in the major groove and to phosphate oxygen in neighboring polynucleotide strands increases the stability of the structure. Hydrogen-bonding appears to be via cis ammine ligands to N(7) and O(6) positions of adjacent purine bases.

Three patients with severe hypertension and rapidly progressive oliguric renal failure who required dialysis were found by aortography to have bilateral renal artery occlusion or stenosis. Each had peripheral arteriosclerosis or an abdominal bruit. Following renal artery reconstructive surgery, all three patients recovered nearly normal renal function in 3 to 12 weeks, though mild hypertension persisted in two patients. The common findings of a normal-sized kidney with collateral blood flow and nearly normal histological features were predictive of recovery of renal function. Prolonged postoperative oliguria in two patients may have been due to increased preglomerular vascular resistance mediated by the renin-angiotensin system.

A comparison is made between the electron density maps of the monoclinic and orthorhombic crystal forms of yeast tRNA Phe which have been obtained respectively by ourselves and by another group. It is concluded that the molecular structures are essentially the same in both crystals, although the models derived from the maps are not the same. The relation between the two molecular packings is discussed, and it is suggested that the intermolecular contact in the orthorhombic form which is not present in the monoclinic form, may arise through base pairing of the anticodons of neighboring molecules.

Channeling effects were estimated by comparing the post-application experience of the treatment and control groups using multiple regression. A variety of potential threats to the validity of the results, including sample composition issues, data issues, and estimation issues, were identified and assessed. Of all the potential problems examined, the only one determined to be likely to cause widespread distortion of program impact estimates was noncomparability of the baseline data. To avoid this distortion, baseline variables judged to be noncomparably measured were excluded from use as control variables in the regression equation. (Where they existed, screen counterparts to these noncomparable baseline variables were used as substitutes.) All of the other potential problems with the sample, data, or regression estimation approach were found to have little or no actual effect on impact estimates or their interpretation. Broad implementation of special procedures, therefore, was not necessary. The study did find that, because of the frequent use of proxy respondents, the estimated effects of channeling on clients' well-being actually may reflect impacts on the well-being of the informal caregiver rather than the client. This and other isolated cases in which there was some evidence of a potential problem for specific outcome variables were identified and examined in detail in technical reports dealing with those outcomes. Where appropriate, alternative estimates were presented.

Zn(Il)- und Co(Il)-Komplexe der Phosphine (I) und (II) werden auf ihre katalytischen Eigenschaften bei der Hydrolyse von p-Nitrophenylpicolinat untersucht.

The photoelectron (pe) spectrum of ascaridole (1) shows an unusually high binding potential for the π-bond. Several possible explanations both conjugative and inductive in nature can be envisioned to account for these observations. To probe which of these mechanisms was prominent, several symmetrical bisallylic oxygen compounds as well as their saturated analogues were synthesised and their pe spectra recorded. Substitution at the allylic centres was chosen to be nearly constant in each case, but the orientation of the symmetrically placed oxygens varied about the π-bond from 0° in ascaridole (1) to 90° in 1,4-dimethoxybicyclo[2.2.2]oct-2-ene (6). In each unsaturated case the position of the ionization attributable to the π-bond is the same. Conjugative interactions of the oxygens with the π-bond cannot account for the pe results since these are expected to show marked dependence upon geometrical constraints. It is postulated that in these systems, the greater electronegativity of oxygen relative to carbo...

Biochemical and instrumental aspects of fibre-optic biosensor development are considered in this study. A sensing process must be capable of transducing the selective chemical binding event into an optical signal. A system showing sensitivity, high selectivity and reversibility was derived from the fluorescence detection of acetylcholine receptor binding to agonist. Fluorescence enhancement was seen for systems where a fluorophore was non-specifically labelled to the receptor/membrane structure and also where only the lipid was fluorescent. The use of intensity ratios at different wavelengths allowed for internal calibration for instrumental drift. Instrumentation for optrode development in an intrinsic configuration was demonstrated by fluorescence from pyrenelabelled concanavalin A adsorbed to the surface of an optical fibre.

In vivo chemical mapping of the human body could be very useful in the treatment of patients undergoing surgery such as heart surgery, with acute conditions such as hepatitis, or chronic conditions such as diabetes. Chemical mapping would be a continuous analytical profile of physical parameters such as blood pressure, chemical parameters such as pH, pCO 2 and p0 2 , simple molecules such as glucose and large biomolecules such as serum glutamate-oxoloacetate trans-aminase (SGOT), serum glutamate-pyruvate transaminase (SGPT) and billirubin. The advantage of a particular mapping strategy employing fibre-optic sensors is that all these different chemical signals arriving from different sensors can be multiplexed and detected concurrently. Although physical sensors for parameters such as temperature, pressure and blood viscosity have not yet found their way into routine use, those which employ fibre-optics do already exist. Fibre-optic chemical sensors (FOCS) have been developed for pH, pCO 2 , p0 2 and 3lucose (for review see Ref. 1). The existing FOCS utilize absorption, reflectance and fluorescence spectro-photometry. An integrated system for chemical mapping could utilize FOCS which exclusively use fluorescence probes which have a high signal to noise ratio and are sensitive to trace amounts of chemicals and biochemicals. One proposed strategy for detecting physiological analytes is the use of fluorescently labelled immunochemicals. These are useful in that the antibodies can be tailored to selectively bind almost any antigen conceivable (2) but are limited in that these reactions are mainly irreversible which is an important consideration for in vivo probes. A second strategy proposed is a receptor-based system (3). While agonist-receptor systems are slightly less selective than antigen-antibody systems, these reactions are reversible which is an important consideration for in vivo probes. Using existing FOCS and a new family of fluorescent chemical sensors that use evanescence, it is possible to multiplex different chemical sensors at different parts of the body to gain a more complete picture of the patient.

The photoelectron spectra of several peroxides and their interpretation is presented. The effects of substituents is separated from vicinal orbital interactions using as a guideline the effect of s...

An optical configuration was developed for sampling fluorescence coupled into an optical fiber from evanescent wave excitation of fluorescent materials at a lipid membrane on a quartz fiber surface. Selective interactions of pyrene-labelled concanavalin A located on a phosphatidyl choline-cholesterol lipid membrane with fluorescein isothiocyanate-labelled dextran in bulk aqueous solution were monitored by the intrinsic fluorescence sensing configuration. Monosialoganglioside, G(M1), was employed as a receptor in a phospholipid membrane on an optical fiber for selective measurement of pyrene-labelled concanavalin A in solution. Quantitative measurement was hindered by non-selective adsorption of cancanavalin A, but the potential for use of a lipid membrane in a fluorometric biosensor was established.

Aus der Abhangigkeit kinetischer Daten fur die saurekatalysierte Hydrolyse der Acetale (I) im pH-Bereich l-l l wird ein gemeinsamer Mechanismus abgeleitet mit einem spaten Ubergangszustand und der C-N-Bindungsspaltung als geschwindigkeitsbestimmendem Schritt.

Studies are being conducted to define and characterize the basic fluid mechanics and heat transfer mechanism controlling the coupling between acoustic and radial profiles of the mean and oscillatory velocity are being measured at several axial stations in a cold flow rocket simulator. Recent studies have concentrated on measuring the structure of the acoustic waves and how this structure relates to the oscillatory heat flux data reported earlier. In particular, the radial profiles of the magnitude and phase (relative to the head end acoustic pressure) of the acoustic velocity have been measured at several axial stations. At low acoustic pressures (i.e., 0.05%) the acoustic waves extend across the entire cross-section in the region upstream of the transition in the mean velocity profile. Nonplaner and nonlinear behavior is also observed in the near surface regions. Downstream of the velocity transition, the acoustic waves do not penetrate through the near wall turbulence. At higher acoustic pressures (i.e., 0.4%) the upstream nonlinearities increase in magnitude and extend across the entire port. Downstream of the velocity transition the core nonlinearities decay while the linear component penetrates through the turbulence to the wall. Originator-supplied keywords include: Velocity coupling; and Combustion instability.

The type II restriction endonuclease EcoRV purified from a genetically engineered, overproducing strain has been crystallized. Four crystal forms all obtained by precipitation with polyethylene glycol 4000 have been characterized. Two of these are suitable for high resolution structure analysis. Both are orthorhombic, have space group P2(1)2(1)2(1) and have similar unit cell dimensions of a = 58.2 A, b = 71.7 A, c = 130.6 A (form A) and a = 59.9 A, b = 74.5 A, c = 121.8 A (form B). They diffract to about 2A resolution and appear to have one dimer of 2 X 29,000 daltons in the asymmetric unit.

The complication rate for all patients receiving total parenteral nutrition (TPN) over a 4-year period of time in a small community hospital has been continuously reviewed. Audit of the complication rate of the initial 15 patients receiving TPN revealed a 12.5% sepsis rate. After instituting rigid protocols concerning catheter insertion and care, a nursing care plan, and metabolic flow sheet, we found that the catheter sepsis rate decreased to 5.1% (P less than 0.05) in the subsequent group of 31 patients. However, metabolic complications related to TPN were not significantly different in the two groups. We conclude that community hospitals without a nutritional team can achieve acceptable complication rates for patients receiving TPN if the staff is committed to continuous critical analysis of complications. Transfer of depleted patients to institutions with demonstrated expertise in this area is recommended if such an analysis shows unacceptable complication rates.

The photoelectron spectrum of the title compound has been determined and found to contain a very low ionization potential. An interpretation of the spectrum and comparison with other cyclobutadienes are presented. The effect of the substituents on the ring and hence on the ionization potential of π2 is discussed.

We performe TSH dry-spot screening as “Central CH-Screening for SH” since 1980. It covers 99,3% of all newborns in this area, the remaining are screened by more than 5 other laboratories. We follow up all cases of CH detected by our screening, either in our department or in collaboration with a local pediatrician. Since January 1980 we screened 95,657 out of 193,854 newborrsin this area. There were 879 recalls for serum with a declining recall rate from 2.23% in 1980 to 0.11% in 1987. Therapy and clinical follow-up was begun in 65 cases, of whom 30 were later considered transient hypothyroidism, 24 of them iodine-induced. Additional 4 children had transient, 2 so far permanent hypothyrotropinemia. The remaining 30 children are still under therapy (L-T4), therefore incidence of CH in our population is 1:3188. We saw seasonal variation in CH-incidence: 15 children were born between Jan. and April, 7 in Sept. and Oct. At about 2 years of age we reevaluate thyroid-function after disruption of T4 substitution, including scintigraphic scan, and intellectual and psychomotor developmental testing. Start of therapy in our patients was at day 6-33 (mean 13.3). Clinical follow-up of the children depicts insufficient L-Thyroxin substitution at one or more occasions in 80%. So far scintigraphic scan during follow-up showed 9 cases with athyreosis, 6 with ectopic thyroid tissue, and 3 with dyshormonogenesis. At age 2-4 mild deficiencies in intellectuel and psychomotor development could be demonstrated as a general trend in our patients, expressed as retardation in performance at or below the 90% level in a standardized testl. Severe retardation in 6 children (28%) as well as the milder forms was focussed on speech, perception, and less pronounced on fine motor abilities. Retardation showed no other correlation then with social status and severe additional illness.