bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the cropping pattern on aflatoxin contamination in preharvest Kharif (monsoon) maize crop (Zea mays)
Authors: Bilgrami Krishna S , Ranjan Kumar S , Masood Ahmad
Published: March 2007

Aflatoxin contamination in three varieties of maize (Zea mays L), viz Diara composite, M9 and Suwan composite, under various cultivation rates and planting densities was examined during the 1987 and 1989 Kharif (monsoon) crops. Cultivation rates comprising single line weeding (SLW) with one spading, SLW with two spadings and SLW with three spadings did not have significant effects on aflatoxin production in the preharvest standing crop. Of the three planting populations, the toxin level was highest under 56000 plants ha−1 followed by 83000 plants ha−1, and 67000 plants ha−1 in Aspergillus flavus inoculated plots (I1) and uninoculated plots (I0), respectively. The variety M9 was most susceptible to A flavus infection and supported higher aflatoxin production under I1 condition. Aflatoxin concentration was lowest in Diara composite. Correlation analysis showed a positive and highly significant relation between A flavus incidence and aflatoxin contamination (r = +0.73, P < 0.01).
Protein, fat and fatty acid composition of Celosia species
Authors: Prakash Dhan , Nath Pashupati , Pal M
Published: March 2007

The seeds of 13 lines of Celosia referable to four species were analysed for protein, fat and fatty acid composition. The protein contents varied from 101 to 170 g kg−1 and fat contents from 56 to 109 g kg−1. The fatty acid composition was of the simple palmitic‐oleic‐linoleic type.
Characterisation of lactose crystallised in acidified aqueous ethanol
Authors: Singh Rakesh K , Shah Basant B
Published: March 2007

Three types of crystalline lactose hydrates having melting points (MP) of 218°C, 195°C and 169°C were crystallised from 680 ml litre−1 ethanol solution with a lactose to solvent ratio of 1:14‐1:24 at three pH values, ∼ 4, 2.5 and 1.3. The three types were characterised on the basis of their optical rotation, phase transition and X‐ray powder diffraction pattern. The samples with high and low MP were α‐lactose hydrates whereas that with the intermediate MP (195°C) was a hydrated lactose containing both α‐ and β‐forms.
Gel filtration studies of peptide metabolism by rumen microorganisms
Authors: Wallace R John
Published: March 2007

Peptide metabolism by rumen microorganisms was investigated by gel filtration using Sephadex G‐25 with water as eluant. Protein hydrolysates containing a mixture of peptides were used to calibrate the column. Total peptide in each fraction was estimated from its A206, and free peptide amino groups were analysed by fluorescamine, thus enabling the average peptide Mr to be calculated. Three different protein hydrolysates produced similar, nearly linear, relations between log Mr and elution volume for peptides between 300 and 2000 Da. Trypticase, a pancreatic hydrolysate of casein, was metabolised rapidly in rumen fluid in vitro. Hydrolysis appeared to be complete after 6 h, leaving a small residual peptide concentration which persisted up to 24 h, equivalent to about 15% of the original peptide concentration of 2 g litre−1. Residual peptides from casein hydrolysis were 0.05 g litre−1 at 24 h. Peptides accumulated in rumen fluid of sheep receiving dietary ionophores. Two hours after feeding, the accumulation with monensin appeared to be of peptides of a wide Mr range, while tetronasin caused an accumulation mainly of smaller, <570 Da, peptides. Treatment of Trypticase with acetic anhydride afforded 76% protection of its peptides from degradation to ammonia in a 6‐h incubation. When Trypticase was fractionated by gel filtration then acetylated, none of the fractions was protected significantly better than others.
Dynamic measurement of tissue rigidity during freezing and cooking of vegetablesa
Authors: Ramana Sundara V , Taylor Andrew J
Published: March 2007

Dynamic oscillatory shear measurements on vegetable tissue were carried out using a modified Weissenberg rheogoniometer. The modified bottom platen and its heating system provided rapid heat transfer and reproducible heating rates. Small discs of tissue (1‐9 mm, 20‐6 mm dia) were attached to the platen and rheological parameters were measured at 30°C. Some tissues gave measurements that were within the linear viscoelastic region; others demonstrated nonlinear behaviour. The applied stress was in phase with the strain, and shear modulus (G′) was therefore the important rheological parameter.

When discs of vegetable tissue were heated in the range 20‐80°C the G′ value rose slightly then declined rapidly. The initial G′ value depended on the type of vegetable used, and there was also sample‐to‐sample variation. Similarly, the temperature at which G′ declined was vegetable dependent. Samples were frozen on the rheogoniometer and then heated from — 18 to 80°C. The change in G′ as the tissue thawed was measured. The technique has limitations if absolute values of G′ are required. However, for comparing the behaviour of different vegetables during heating and cooling, the technique allows dynamic measurements to be made.
Unusual fatty acids of Cordia rothii seed oil
Authors: Daulatabad Chirag Mahmood Jehan D , Desai Vijayaraj A , Hosamani Kallappa M
Published: March 2007

The seed oil of Cordia rothii Roem and Schult, syn Cordia angustifolia Roxb. belonging to the family Boraginaceae contains ricinoleic (10.8 %), malvalic (2.5%), sterculic (1.5%), myristic (2.4%), palmitic (32.8%), stearic (2.2%), oleic (7.8%) and linoleic (40.0%) acids.
Spatially heterogeneous impacts on rangeland after social system change in Mongolia
Authors: Okayasu T. , Muto M. , Jamsran U. , Takeuchi K.
Published: March 2007

After the social system in Mongolia changed from socialism to capitalism in the early 1990s, the cooperative system called negdel, which helped to disperse the grazing pressure, collapsed. As a consequence of the collapse, scientists warned that grazing pressure would become concentrated and fixed at particular locations, resulting in land degradation. However, no quantitative studies of such potential local concentration have been performed in Mongolia. In this study, using satellite images and large‐scale thematic maps, we analysed the local vegetation change in relation to possible control factors, including open water, roads and settlements. Individual factors had significant impacts on the local vegetation change: particularly prominent were a beltlike decrease in plant density along the main roads and decreases around densely populated areas. In addition, the interaction between these factors negatively affected vegetation, as seen by a decrease around roads and open water near settlements. This interactive effect is likely a consequence of the basic requirements of the nomadic pastoralists, namely quality grassland, water sources and the services provided by settlements. In our study area in Mongolia, the local pattern of vegetation change was determined by the complex process of pastoralists' decision‐making. A comprehensive understanding of this process is essential for devising management plans to counteract this vegetation degradation. Copyright © 2007 John Wiley & Sons, Ltd.
Inside‐outl vein graft repair compared with nerve grafting for nerve regeneration in rats
Authors: Wang Kai‐Kai , Costas Paul D. , Bryan David J. , Eby Patricia L. , Seckel Brooke R.
Published: March 2007

The inside‐out vein graft is a vein conduit pulled through itself to invert the normal orientation and place the adventitial layer within the lumen of the conduit. Our study compares regeneration of peripheral nerves in the rat through two conduits: inside‐out graft of the jugular vein and autogenous nerve graft. In 10 rats, the right jugular vein was harvested, turned inside out, and used to bridge a 10 mm defect created in the right sciatic nerve. The 10 mm nerve segment from the right was then used as a standard nerve graft to bridge a 10 mm gap created in the left sciatic nerve. Rats were sacrificed at 8 and 12 weeks. Regeneration on the inside‐out vein graft side showed superior functional results (faster conduction velocities) and improved histological results (greater axon counts) compared with the nerve grafted side. We feel the adventitial surface of the wall of the vein promotes nerve regeneration by providing an environment rich with collagen, laminin, and Schwann cells and promotes increased vascularization of the new nerve. © 1995 Wiley‐Liss, Inc.
Axillary plexus blockade in microvascular surgery, a steal phenomenon?
Authors: van der Werff John. F. A. , Medici Georgio , Hovius Steven E. R. , Kusuma Arie
Published: March 2007

A case report is presented of an axillary plexus blockade following a second toe‐to‐hand transfer. After completion of the microvascular anastomoses and restoration of blood flow to the transplanted toe, the axillary plexus blockade was started. Together with the vasodilation of the hand and forearm there was a marked drop in blood flow in the transplanted toe. Possible explanations for this phenomenon are considered. We suggest starting axillary plexus blockade before completion of microvascular anastomoses and maintaining a continuous postoperative blockade. © 1995 Wiley‐Liss, Inc.
Reconstructive microsurgery of lymph vessels: The personal method of lymphatic‐venous‐lymphatic (LVL) interpositioned grafted shunt
Authors: Campisi C. , Boccardo F. , Tacchella M.
Published: March 2007

Our clinical observations in 64 patients affected by chronic obstructive lymphedema (either arm or leg) undergoing interposition autologous lymphatic‐venous‐lymphatic (LVL) anastomoses are reported. This microsurgical technique is an alternative to other lymphatic shunting methods, especially when venous dysfunction coexists in the same limb and, therefore, when direct lymphatic‐venous anastomosis is accordingly inadequate. Preoperative diagnostic evaluation (including lymphatic and venous isotopic scintigraphy, Doppler venous flowmetrics, and pressure manometry) plays an essential role in assessing the conditions of both the lymphatic and venous systems and in establishing which microsurgical procedure, if any, is indicated. Our microsurgical technique consists of inserting suitably large and lengthy autologous venous grafts between lymphatic collectors above and below the site of obstruction to lymph flow. The data show that, using this technique, both limb function and edema improved, and in all patients followed up for over 5 years edema regression was permanent. © 1995 Wiley‐Liss, Inc.
Testicular autotransplantation for the intra‐abdominal testis
Authors: Bukowski Timothy P. , Wacksman Jeffrey , Billmire David A. , Sheldon Curtis A.
Published: March 2007

Oftentimes patients with intra‐abdominal testes require more than the standard procedure to accomplish orchiopexy. Division of the spermatic vessels has been one mainstay of operative approaches for the intra‐abdominal testis since Fowler and Stephens (Congenital Malformations of Rectum, Anus, and Genitouriary Tracts, chapter 19, pp 306–320, 1963) provided an anatomically rational basis for this procedure. Silber and Kelly (J Urol, 115:452–454, 1976) first described using a microvascular anastomosis to bring extra blood supply to the testicle after mobilization of a high intra‐abdominal testicle into the scrotum; however, this approach has not been adopted by many for a number of reasons. The microvascular skill and instrumentation required for a successful anastomosis are not universally available and there is a misconception that the procedure is a lengthy one (Bianchi, Br J Urol 56:521–524, 1984; Bogaert et al., Urology 42:182–188, 1993). We present our series for testicular autotransplantation used over a 17 year period with a greater than 95% success. © 1995 Wiley‐Liss, Inc.
Gamete microsurgery for assisted fertilization
Authors: Sparks Amy E. T.
Published: March 2007

Several methods of gamete microsurgery have been proposed to facilitate the union of the spermatozoon and oocyte in infertile couples. Partial zona dissection, subzonal sperm insertion, and intracytoplasmic sperm insertion are the three techniques currently being used for assisted fertilization in human in vitro fertilization laboratories. Fertilization and pregnancy rates after partial zona dissection and subzonal insertion have been variable and rather low. Recent reports of relatively high fertilization and pregnancy rates achieved after intracytoplasmic sperm insertion have rejuvenated interest in gamete microsurgery. Methods for each procedure are described. Studies which have attempted patient selection for gamete microsurgery are discussed. © 1995 Wiley‐Liss, Inc.
Plea to save the great toe in total thumb reconstruction
Authors: Foucher G. , Binhammer P.
Published: March 2007

Thumb reconstruction remains a controversial field. In young, well‐motivated patients, in the absence of avulsion injuries, toe to hand transfer is an accepted procedure. With refinement, it is possible to avoid sacrifice of the great toe and in many cases avoid resorting to a second toe which is functionally and cosmetically insufficient. Custom‐made reconstruction allows us both to save the donor great toe and to improve function and cosmesis of the donor site. Three basic techniques are reviewed: the modified wrap‐around, bipolar lengthening, and twisted two‐toes techniques. © 1995 Wiley‐Liss, Inc.
The free vascularised fibular transfer as a definitive treatment in femoral septic non‐unions
Authors: Nonnenmacher J. , Bahm J. , Moui Y.
Published: March 2007

Free vascularised bone transfer (fibula, iliac crest, or rib) is an accepted method of bone grafting in malignant and nonunion bone surgery. The vascular microanastomoses have transformed the bone healing by creeping substitution seen after non‐vascularised grafting (a long and often insufficient process) into normal healing of the fracture site. The presence of its own vascular support allows bone healing in such compromised circumstances as sclerosis and infection. We present the clinical history of five patients with septic femoral non‐unions, in which only the final vascular fibular graft provided an acceptable outcome. Discussion about the indication and timing of this microsurgical salvage procedure is still controversial. © 1995 Wiley‐Liss, Inc.
Complications of free flap donor sites
Authors: Mahoney James
Published: March 2007

A variety of free tissue transfers are available for microsurgical reconstruction. To date little attention has been placed on the donor site, both from the potential for acute complications as well as long‐term morbidity. In this review the various types of tissue transfers in different anatomical locations have been assessed for potential problems at the donor site. An assessment system is proposed to better evaluate this problem as well as to allow comparison of the different donor sites. © 1995 Wiley‐Liss, Inc.
Microvenous thrombosis rates following anastomosis with vein grafting and a knotted suture
Authors: Zhang Feng , Üstüner Tuncay , Walker Richard , Buntic Rudolf , Lineaweaver William C.
Published: March 2007

An experimental microvenous thrombosis model was developed combining vein grafting in femoral vein defects with exaggerated vessel injuries using a knotted suture in the vessel repair. The rat femoral vein grafts were separately subjected to injuries caused by an anastomosis performed with a suture knotted with eight half‐hitches at the distal anastomosis (upstream), the proximal anastomosis (downstream), and both anastomotic sites. These groups were compared to vein grafting done with a standard suture. Vessel patency was assessed at 20 min and 24 hr, and the thrombus component was histologically analyzed at 24 hr after the procedures. One hundred percent of control vein grafts were patent at 24 hr. All experimental groups had significantly decreased patency at 24 hr (P<0.001). Among the experimental groups, knotted suture anastomoses at both anastomoses produced significantly lower patency (13.3%, P<0.05) than knotted suture anastomoses at distal anastomoses. Histological analyses of thrombosed grafts showed that a large amount of thrombocyte deposition and inflammatory cells were noted at both anastomotic sites in the vein grafts with a knotted suture at the distal anastomosis and in the grafts with a knotted suture at both anastomoses. Thrombocyte deposition and inflammatory cells were seen only at the site of proximal anastomosis when using a knotted suture at the proximal anastomosis site alone. This study demonstrated that quantified microvenous thrombosis can be produced by exaggerating vessel injuries with a knotted suture in a vein graft model. This thrombosis model can be used to study the effects of antithrombogenic agents. © 1995 Wiley‐Liss, Inc.
Use of ultrasonography to evaluate muscle thickness and blood flow in free flaps
Authors: Salmi Asko , Ahovuo Juhani , Tukiainen Erkki , Härmä Markku , Asko‐Seljavaara Sirpa
Published: March 2007

The purpose of this study was to investigate the common belief that a microvascular transfer of a non‐innervated free muscle flap loses muscle bulk over time. Sixteen patients (latissimus dorsi = 8, rectus abdominis = 7, and gracilis muscle = 1) were evaluated an average of 41 months after free flap transfer. Latissimus dorsi and lower extremity flaps displayed significantly more swelling than the other flaps. Flap bulk was measured by ultrasound. The mean thickness of upper extremity flaps was 10.3 ± 1.8 mm (control muscles 11.8 ± 2.8), lower‐extremity 14.5 ± 3.7 mm (control muscles 10.9 ± 0.7), latissimus dorsi 14.3 ± 2.2 mm (control muscles 10.3 ± 0.8, P = 0.018), and rectus abdominis 11.2 ± 1.2 mm (control muscles 12.4 ± 1.9). Color Doppler ultrasonography was used to detect the pedicles of the free flaps and also to measure the peak velocity of blood flow intramuscularly and in the pedicles. In the upper extremities (n = 5) the pedicles could be found in only 20% of cases whereas in the lower extremities (n = 11) 91% of pedicles were located. (P = 0.013). Peak flow within the free flaps was significantly higher in the lower extremity (50% of the peak flow of the common femoral artery) than in the upper extremity (5% of the peak flow of the common femoral artery, P = 0.013). This study demonstrated that non‐innervated free muscle flaps in the extremities maintain the original muscle thickness, although lower extremity and latissimus dorsi flaps have a trend to be thicker. Most pedicles of free muscle flaps in the upper extremities could not be located by ultrasound. However, flaps in the lower extremities most often have patent pedicles and also more vigorous intramuscular blood flow. © 1995 Wiley‐Liss, Inc.
Composition and relaxation of the proton magnetization of human enamel and its contribution to the tooth NMR image
Authors: Funduk N. , Kydon D. W. , Schreiner L. J. , Peemoeller H. , Miljković L. , Pintar M. M.
Published: March 2007

The spin‐spin, T2, and spin‐lattice, T1, relaxation times and the magnetization of protons were measured in human enamel. The proton free induction decay was analyzed into solid‐like interstitial water, enamel apatite, and semiliquid‐like water components. The solid‐like interstitial water was evaluated to be ∼5 wt% and the semiliquid‐like water to be ∼1 to 2%. Neither in wet nor in dry natural enamel does the solid water exchange upon deuteration nor can it be extracted in vacuum. The semiliquid natural water, which is in the closed pores of the structure in the two samples above also remains unexchanged upon an 8 hr deuteration and connot be extracted in a vacuum. With the lineshape‐relaxation correlation NMR the free induction decays from heads and tails of the enamel rods were resolved. The solid‐like water with T2 of ∼14 m̈sec and the appatite with a T2 of ∼61 m̈sec have T2's too short to be observed in an NMR zeugmatogram. Therefore only the similiquid water component having an apparent T*2 of about 240 m̈sec would contribute ot the NMR image of human enamel. Since the relative intensity of this proton magnetization component in tooth in quite small the NMR image of tooth would show primarily the dentin and liquids within the tooth and on its surface.
A Parallel Algorithm for Rotating‐Frame Zeugmatography
Authors: Chen C.‐N. , Hoult D. I. , Sank V. J.
Published: March 2007

An algorithm, which utilizes a high degree of parallel processing, has been developed for two‐dimensional rotating‐frame zeugmatography so that a picture of 256 X 256 pixels can be generated with a minicomputer system 2 sec after data accumulation. An array processor is employed as a second processor and, the refresh memory of a display unit is used as a fast data storage entity. Approximately half the calculations are carried out in the array processor during the nuclear relaxation period. Data movement to and from the display memory occurs largely during, and in parallel with, the array processing. The sequence can be run at a repetition rate of 35 msec per free induction decay and the algorithm can be implemented in any two‐dimensional experiment of the Fourier transform genre.
The Installation of High‐Field NMR Equipment in a Hospital Environment
Authors: Bore Peter J. , Timms William E.
Published: March 2007

Installing high‐field magnets in hospital environments has implications for safety, for the performance of the equipment and for the well‐being of the subjects who will be examined. This paper outlines the relevant properties of magnets and identifies the requirements necessary for a safe and usable installation. One approach to the meeting of these requirements is described.
Analysis of multiple T2 proton relaxation processes in human head and imaging on the basis of selective and assigned T2 values
Authors: Gersonde K. , Felsberg L. , Tolxdorff T. , Ratzel D. , Ströbel B.
Published: March 2007

Two‐dimensional T2‐selective proton imaging of human head has been performed at 10 MHz employing Carr‐Purcell‐Gill‐Meiboom pulse trains with echo separation of 6 and 12 msec. Using the information of 36 spin echoes and applying a recovery time of 2 sec the magnetization decay has been traced. The multi‐exponential T2 relaxation curve of each pixel of the image has been deconvoluted into up to three monoexponential functions which are defined by 1/T2,i and αi. The T2,i values are represented in a T2 histogram of the slice and then selected for generating images which relate to protons with specific T2. The αi values indicate the relative amounts of the T2‐selected protons. Imaging on the basis of α2 values increases the contrast of the image. The multiple T2‐selective imaging technique leads to head images which show selectively cerebrospinal fluid, gray matter, different types of white matter, and nonassigned fast‐relaxing proton classes.
Proton magnetic relaxation in aqueous glycerol solutions containing manganese(II) Ion
Authors: Kennedy Scott D. , Bryant Robert G.
Published: March 2007

The proton nuclear magnetic relaxation rate, 1/T1, is reported as a function of d5‐ glycerol concentration for aqueous manganese(II) ion solutions over a range of magnetic field strengths corresponding to proton Larmor frequencies between 0.01 and 38 MHz. The data are analyzed in terms of the Solomon, Bloembergen, and Morgan equations which are found to be sufficient to account for the relaxation data over the field and concentration ranges studied. These data provide a useful reference for the viscosity dependence of manganese(II)‐ion‐induced magnetic relaxation in aqueous systems and a useful comparison with macromolecule bound manganese(II)‐ion‐induced relaxation where the theory is less successful.
Application of multipulse NMR to observe 13C‐labeled metabolites in biological systems
Authors: Bendall M. Robin , Hollander Jan A. Den , Arias‐Mendoza Fernando , Rothman Douglas L. , Behar Kevin L. , Shulman Robert G.
Published: March 2007

Limitations in resolution and sensitivity of 13C NMR spectroscopy have reduced the information obtainable from intact biological systems. With the aim of increasing the information from in vivo 13C NMR two multipulse NMR techniques, the DEPT pulse sequence and the gated spin‐echo sequence, were used to obtain edited 13C NMR spectra from different 13C‐labeled mammalian tissues. This allowed the separation of the 13C NMR signals from the tissues into subspectra containing either CH, CH2, or CH3 signals, thereby increasing the information obtainable from these spectra. Comparing the two techniques, the DEPT sequence gives more accurate editing than the gated spin‐echo sequence but suffers from the difficulty of determining 1H pulse angles in vivo.
A versatile perfusion technique for metabolic studies by NMR
Authors: Geoffrion Yves , Lareau Sylvain , Deslauriers Roxanne , Butler Keith , Pass Michael , Smith Ian C. P.
Published: March 2007

A perfusion technique applicable to metabolic studies by NMR is described in detail. The utility and versatility of the approach are demonstrated by following gluconeogenesis from [2‐13C]pyruvate in the perfused, isolated mouse liver, and lipogenesis from [2‐13C]acetate in perfused Acanthamoeba castellanii cells embedded in agarose filaments.
Apparent changes of appearance of inversion‐recovery images
Authors: Young I. R. , Bailes D. R. , Bydder G. M.
Published: March 2007

This note considers the anomolous contrast in inversion recovery images produced by NMR scanners if a map |My′| is reconstructed, rather than a map of My′.
Significance of histopathology in pulsed NMR studies on cancer
Authors: Ranade S. S. , Bharade S. H. , Talwalkar G. V. , Sujata G. K. , Shrinivasan V. T. , Singh B. B.
Published: March 2007

Characterization of tissue by pulsed nuclear magnetic resonance spectrometry opened a new area of research. The differences in the NMR parameters T1 and T2 of normal and malignant tissues constitute the basis for their distinction by pulsed NMR spectrometry and also by NMR imaging in vivo. The present studies were undertaken to correlate the role of constituent histological elements encountered in various maligancy‐associated changes and T1 variations and are based on evaluation of samples taken from surgically resected specimens of carcinoma of the esophagus, comprising the uninvolved portions of the esophagus and the gastric end on gross examination. The uninvolved and involved regions showed low and high T1 values, respectively. High T1 values were also encountered in the zones of samples of uninvolved esophagus which histologically revealed areas with dysplasia. This feature, viz., dysplasia representing maligancyassociated changes, has been found to recur in many samples. Detailed histological studies provided further evidence confirming that areas with dysplasia contribute to an increase in T1 values whereas in zones at the gastric end metaplasia and hyperplasia are more common. The results are of value for demarcation of tumor area by in vivo NMR imaging.
Strategies and tactics in NMR imaging relaxation time measurements. I. Minimizing relaxation time errors due to image noise—the ideal case
Authors: Kurland Robert J.
Published: March 2007

The effect of NMR image noise on erros in calculated values of relaxation times is quantitatively assessed by use of relaxation time noise figures, which are derived on the basis of statistical principles as functions of pulse delay, repetition, and recovery intrvals for several types of pulse sequences. Two strategies for determining relaxation times are considered: two point (ratio of intensities for two experiments) and multipoint (least‐squares fit of intensities to pulse‐sequence functions for n experiments). For given total measurement times, values of pulse interval times are found which give minimum relaxation time noise figures. A comparison of ratio methods shows that the best is a combination saturation ‐recovery inversion‐recovery (SR/IR) technique. For short measurement times (less than about 10T1) this optimized SR/IR ratio determination is also superior to the best multipoint method, a series of inversion—recovery experiments with equally incremented inversion‐recovery times. An examination of the effect of signal averaging on the relaxation time noise shows that up to a measurement time characteristic of the particular method used (e. g., for times up to about 5T1 for the SR/IR ratio determination, 100T1 for the multipoint inversion‐recovery method), increased measurement time is more effectively allotted to longer pulse intervals than to signal averaging. Numerical examples are tabulated which can help one to set optimum values for pulse intervals, given a rough estimate of the relaxation time to be determined.
Proton Imaging with Surface Coils on a 0.15‐T Resistive System
Authors: Fitzsimmons Jeffrey R. , Thomas Ray G. , Mancuso Anthony A.
Published: March 2007

Coil development is fundamental to the optimization of imaging systems at any field; however, it is especially critical for low‐field systems where signal strength is limited. Here we demonstrate a type of surface coil design which makes possible the acquisition of high‐quality images of the neck and extremities.
Chemical‐shift imaging using filtered back‐projection algorithms
Authors: Haselgrove John , Gilbert K. , Leigh J. S.
Published: March 2007

A method of performing chemical‐shift imaging is described that avoids some of the disadvatages inherent in the techniques which use spin echos and phase encoding. A series of FIDs are recorded during the application of a series of static gradients and the spectral image is reconstructed using a conventional filtered back‐projection algorithm.
Chemical‐shift artifact correction scheme using echo‐time encoding technique
Authors: Cho Z. H. , Nalcioglu O. , Park H. W. , Ra J. B. , Hilal S. K.
Published: March 2007

An investigation has been undertaken to study the effects of chemical shift on NMR image obtained by the projection reconstruction technique. Mathematical simulation studies indicate that chemical shift causes blurring in NMR images regardless of the image reconstruction technique. A systematic study of such artifacts is presented and possible correction schemes are proposed. Exemplary results with and without correction of the chemical‐shift artifact and pulse schemes employed for projection reconstruction are presented. The present chemical‐shift correction scheme is basically the same as a spectroscopic imaging technique such as the existing 4‐D NMR imaging method except that the encoding steps required can be reduced substantially in the case of modest spectroscopic resolution.
In Vivo Nuclear Magnetic Resonance Imaging of Lithium
Authors: Renshaw Perry F. , Haselgrove John C. , Leigh John S. , Chance Britton
Published: March 2007

Magnetic resonance imaging techniques have previously been applied to 1H, 23Na, 31P, and 19F nuclei. This is the first report of application of these techniques to 7Li. Lithium images of both aqueous phantoms and a rat abdomen are presented. Applications of this technique to humans are discussed.© 1985 Academic Press,Inc.
A Method for Chemical‐Shift‐Selective Imaging
Authors: Dumoulin Charles L.
Published: March 2007

Selective suppression of a given resonance in an NMR image can be obtained with a π/2 pulse whose excitation spectrum in zero at the appropriate chemical shift. The selective π/2 pulse presented here is composed of two nonselective π/2 pulses of opposite phase. The two pulses are separated by a short interval which determines the excitation spectrum.© 1985 Academic Press,Inc.
The sectorial loop‐gap resonator for 31P NMR of the adult human liver at 1.5 t with surface tissue suppression
Authors: Jesmanowicz A. , Froncisz W. , Grist Thomas M. , Hyde James S.
Published: March 2007

A new type of loop‐gap resonator, which because of its topology is called a “sectorial resonator,” is described in considerable analytical detail. It was used for 31P NMR of the livers of two human adult normal volunteers. An effective strategy for suppression of signals from surface tissue was developed. Depth selection was achieved using a separate excitation coil, permitting a reasonable degree of control of the shape of the sensitive region by adjustment of the dimensions of the excitation coil and of the type of pulse delivered. In addition a new principle for cancellation is described: the topology of the sectorial resonator leads to cancellation signals from tissue masses at the two openings of the structure. Using a phase‐altenated repeated 90° FID pulse sequence, good spectra were achieved in 2.5 min that are free from contamination by the phosphocreatine peak. © 1986 Academic Press, Inc.
Are quenches dangerous?
Authors: Bore P. J. , Galloway G. J. , Styles P. , Radda G. K. , Flynn G. , Pitts P. R.
Published: March 2007

There exists some uncertainty about the hazards which the quenching of a superconducting magnet would present to a subject undergoing an NMR examination. To investigate this problem, a 1.6‐T whole‐body magnet was quenched with an anesthetized pig lying in the bore. This paper reports our finding which, in the circumstances of this experiment, suggest that the risks are small. © 1986 Academic Press, Inc.
In vitro1H NMR “mapping” of human intervertebral discs
Authors: Furó I. , Bobest M. , Pócsik I. , Tompa K.
Published: March 2007

Human intervertebral discs were investigated by 1H NMR in vitro. The measured parameters of samples differently located in discs give the “maps” of discs. The spin‐lattice relaxation‐time maps show similar structure to dry matter and bound water maps, which might mean the future possibility to detect certain disc processes via accurate T1 images. © 1986 Academic Press, Inc.
The cryoprotective effects of dimethyl sulfoxide on human bone marrow as studied by 31P nuclear magnetic resonance spectroscopy
Authors: Brauer Manfred , Penney Heather F. , Janowska‐Wieczorek Anna , Sykes Brian D.
Published: March 2007

31P nuclear magnetic resonance spectroscopy has been used to study freshly aspirated normal human bone marrow samples. The pH within the intact cells of the samples was determined from the chemical‐shift position of the resonance for inorganic phosphate within the cell; the intracellular pH was found to be 7.35 for fresh bone marrow. The chemical‐shift positions of the α and β phosphate resonances of adenosine 5′‐triphosphate were used to assess the fraction of this metabolite complexed with Mg2+. It was found that 84% of the total intracellular adenosine 5′‐triphosphate was in the Mg2+‐complexed form. The concentration of Mg2+ uncomplexed to any ligand was 0.4 mM. The areas of the resonances for the major phosphorus‐containing metabolites were used to determine intracellular concentrations. For fresh human bone marrow, the intracellular concentrations determined were phosphate monoesters < 0.3 mM, 2,3‐diphosphoglycerate 3.9 ± 1.0 mM, inorganic phosphate 1.2 ± 0.6 mM, phosphodiesters 2.8 ± 1.0 mM, adenosine 5′‐triphosphate 1.6 ± 0.4 mM, adenosine 5‐diphosphate < 0.2 mM, and nicotinamide adenine dinucleotide < 0.2 mM. These metabolite concentrations within the intact cell samples did not change over 2.0 h and changed only gradually over a 24‐h period. 31P nuclear magnetic resonance spectroscopy was then used to study the cryopreservation of normal human bone marrow in the presence of increasing concentrations of the penetrating cryopreservative dimethyl sulfoxide. Dimethyl sulfoxide alone without freezing was found to cause some gradual hydrolysis of 2,3‐diphosphoglycerate, presumably by stimulating diphosphoglycerate phosphatase. The effect of freezing human bone marrow to liquid nitrogen temperatures, storage, and rapid thawing was a dramatic fall in intracellular adenosine 5′‐triphosphate levels. The half‐life of the metabolite, after thawing, was about 0.3 h. If the bone marrow was frozen in the presence of 2.5, 5.0, and 7.5% dimethyl sulfoxide, the post‐thaw half‐life was prolonged to 0.4, 0.5, and 0.6 h, respectively. 15% dimethyl sulfoxide afforded complete cryoprotection, with adenosine 5′‐triphosphate levels constant for 15 h after thawing the human bone marrow. © 1986 Academic Press, Inc.
Application of anatomically shaped surface coils in MRI at 0.5 T
Authors: Doornbos J. , Grimbergen H. A. A. , Booijen P. E. , te Strake L. , Bloem J. L. , Vielvoye G. J. , Boskamp E.
Published: March 2007

The construction and application of eight different MRI surface coils is described. The coils consist of an anatomically shaped copper wire loop as an antenna and a printed circuit board containing electronic components for tuning and matching. The electronic device for tuning and matching is interchangeable between the various coils. Surface coils for signal detection yield images with high signal‐to‐noise ratio in comparison to the usual saddle‐shaped head or body coils. The sensitivity of a surface coil decreases with increasing distance between the coil and the object of interest and therefore the coils are constructed to fit the anatomical structure under examination as well as possible. The application of dedicated surface coils for superficial structures in the body extends the possibilities of the MRI system. Photographs of the coils positioned on the body and MR images of volunteers and patients are shown. © 1986 Academic Press, Inc.
Effects of antimalarial drugs on oxygen consumption by erythrocytes infected with Plasmodium berghei: An ESR study
Authors: Butler Keith W. , Deslauriers Roxanne , Smith Ian C. P.
Published: March 2007

Oxygen consumption in mouse erythrocytes infected with Plasmodium berghei has been followed by electron spin resonance (ESR) spectroscopy of nitroxide radical spin probes. The parasitized red cell suspension is mixed with the spin probe CTPO (3‐carbamoyl‐2, 2, 5, 5‐tetramethyl‐3‐pyrrolin‐1‐yloxy) in a closed chamber. Oxygen consumption is monitored by the increasing resolution of the superhyperfine splittings of the spin label. The antimalarial drugs quinacrine, primaquine, and quinine are shown to decrease the rate of oxygen consumption of the parasitized erythrocyte suspensions. The spin‐label method offers advantages over conventional polarographic and spectrophotometric assays for highly parasitized cell populations where cells are fragile and contain oxidized hemoglobin as well as hemoglobin‐derived pigments.
Echo shape analysis and image size adjustment on the level of echoes: Improvement of parameter‐selective proton images
Authors: Staemmler M. , Gersonde K.
Published: March 2007

Parameter‐selective imaging for tissue characterization is performed at low magnetic fields (0.24–0.28 T) employing echo trains with a large number of echoes (≦50), high‐power pulses, and the projection reconstruction method. Preprocessing of the raw echoes is important for the quality of the echo images which are the bases for further evaluation and generation of parameter‐selective images. Two new algorithms are implemented in the image preprocessing routine TOMIKON: Echo shape analysis and image size adjustment. Echo shape analysis allows the detection and the removal of spikes in the echo signals to avoid image artifacts. Image size adjustment is performed by expanding and contracting the time basis of the echoes resulting in a size normalization of the echo images, an indispensable condition for generating diffusion images. © 1986 Academic Press, Inc.
Present and future clinical position of magnetic resonance imaging
Authors: Steiner Robert E.
Published: March 2007

Following the appearance of the first clinical reports on magnetic resonance imaging (MRI) five years ago, stock is now taken of the clinical value of this new imaging technique and its future potential is assessed. Contrast and spatial resolution as well as specificity of CT and MRI are compared and the multiplicity of sequences, multiplanar facility, and flexibility of MRI over CT are analyzed. The dominant role of MRI over CT in the study of some disorders of the central nervous system is assessed and so are the limitations. In this context the usefulness of paramagnetic contrast media is also evaluated. The difficulties of body imaging are discussed. The solutions of overcoming cardiac and respiratory motions artifacts are evaluated and areas where MRI has already achieved a high level of clinical application are identified. Mention is made of additional information obtainable by MRI as, for example, sodium imaging, blood flow measurements, and the combination of imaging with spectroscopy. Possible future prospects are analyzed, for example, high‐resolution imaging, alternative sequences to those commonly used in particular the short T1 IR se‐quence (STIR), chemical shift imaging, and the possibility of utilizing susceptibility for imaging purposes. The problem of radiofrequency receiver coil design is approached and so is the choice of magnetic fields. The future relationship of MRI with established non‐invasive techniques is stressed. © 1986 Academic Press, Inc.
Modified crossed‐ellipse radiofrequency coil for MRI
Authors: de Luca F. , Crescenzi A. , Luzzi M. , De Simone B. C. , Campanella R. , Casieri C. , Maraviglia B.
Published: March 2007

New coil geometries obtained by computer simulations from the crossed‐ellipse rf coil are reported. These geometries with elliptical transverse section improve the signal‐to‐noise ratio with respect to the classic ellipse and saddle coils. The increase of signal‐to‐noise ration is mainly due to the reduction of coil losses and to the better B1 efficiency and distribution. © 1986 Academic Press, Inc.
Counter rotating current local coils for high‐resolution magnetic resonance imaging
Authors: Froncisz W. , Jesmanowicz A. , Kneeland J. Bruce , Hyde James S.
Published: March 2007

A type of local coil (or surface coil) for magnetic resonance imaging and spectroscopy is described in which two circular loops of the same diameter are disposed axially with respect to each other and in which counter rotating currents (CRC) are supported in the two loops. This type of coil has been used for localized reception in a uniform circularly polarized excitation field produced by a whole‐body coil of an imager functioning at 1.5 T. The CRC coil is decoupled from the transmitter coil by a combination of intrinsic (or geometrical) isolation (which functions during both excitation and reception) plus passive decoupling (which functions only during excitation). CRC coils of 7.5, 10, 12.5, and 15 cm diameter have been compared on a bench test setup with conventional surface coils of these diameters. Sensitivities are very similar. Q's have been measured as a function of coil diameter and both Q's and frequency shifts have been measured as a function of distance from a saline tank. The CRC coil appears to have advantages with respect to tuning and matching. A high‐resolution image of the rotator cuff is shown as an illustration of coil performance. © 1986 Academic Press, Inc.
The intrinsic signal‐to‐noise ratio in NMR imaging
Authors: Edelstein W. A. , Glover G. H. , Hardy C. J. , Redington R. W.
Published: March 2007

The fundamental limit for NMR imaging is set by an intrinsic signal‐to‐noise ratio (SNR) for a particular combination of rf antenna and imaging subjects. The intrinsic SNR is the signal from a small volume of material in the sample competing with electrical noise from thermally generated, random noise currents in the sample. The intrinsic SNR has been measured for a number of antenna‐body section combinations at several different values of the static magnetic field and is proportional to B0. We have applied the intrinsic and system SNR to predict image SNR and have found satisfactory agreement with measurements on images. The relationship between SNR and pixel size is quite different in NMR than it is with imaging modalities using ionizing radiation, and indicates that the initial choice of pixel size is crucial in NMR. The analog of “contrast‐detail‐dose” plots for ionizing radiation imaging modalities is the “contrast‐detail‐time” plot in NMR, which should prove useful in choosing a suitable pixel array to visualize a particular anatomical detail for a given NMR receiving antenna. © 1986 Academic Press, Inc.
Multiple‐spin‐echo imaging with a 2D Fourier method
Authors: Graumann R. , Oppelt A. , Stetter E.
Published: March 2007

In 2D Fourier imaging the normal Carr‐Purcell multiple‐echo sequence generally leads to center line and mirror artifacts caused by imperfect rotations by the rf pulses. We describe a method to avoid these distortions using a phase alternating‐phase shift (PHAPS) sequence which also allows multiple‐slice and multiple‐echo imaging at the same time. Measuring phantoms with calibrated T2 values, we have shown that the PHAPS imaging sequence leads to an accuracy of quantitative T2 determinations of better than 10%. Contrast‐enhanced images are presented which we calculated from multiple‐echo images and extrapolated to arbitrary echotimes, including negative ones. We believe that these improvements in T2 imaging will result in a significant reduction of patient investigation time in magnetic resonance imaging. © 1986 Academic Press, Inc.
The field dependence of NMR imaging. II. Arguments concerning an optimal field strength
Authors: Hoult D. I. , Chen C‐N. , Sank V. J.
Published: March 2007

Some of the factors involved in the choice of field strength for NMR imaging are examined. The influences of relaxation times and chemical shift upon image quality and signal‐to‐noise ratio are highlighted, and power deposition is introduced as a significant factor which may limit the flexibility and information available at higher fields as long as 180° echo pulses continue to be necessary. Chemical‐shift imaging is examined and found wanting as a means of coping with chemical‐shift artifacts, and the use of multiple echoes (albeit with research) in conjunction with multiple‐slice techniques is advocated as representing an efficient data‐gathering scheme which can improve image signal‐to‐noise ratio. With such use, a medium field strength (0.5–1 T) is presented as representing, for general purpose imaging of head and torso, the best current compromise when imaging time is of major importance, with the important caveat that new techniques may always invalidate this conclusion. © 1986 Academic Press, Inc.
In vitro proton T1 and T2 studies on rat liver: Analysis of multiexponential relaxation processes
Authors: Barthwal R. , Höhn‐berlage M. , Gersonde K.
Published: March 2007

At 37°C and 20 MHz, the T1 and T2 proton relaxation processes in intact rat liver tissue are multiexponential functions which in the majority of cases were decomposed into a major (α* ≈ 90%, T = 374 ms, T = 58 ms) and a minor (α** ≈ 10%, T = 130 ms, T = 181 ms) component. Both, T1 and T2, are temperature‐dependent with a temperature shift of ΔT1 = 1.5 ms/°C and ΔT2 = 0.5 ms/°C, respectively. Storage of liver tissue at 4°C and 37°C led to remarkable changes of the T1 and T2 values. For T2 these changes occurred after a shorter storage time than for T1, but they are more pronounced for T1, To avoid such influences the relaxation measurements were performed within one hour after excision of the tissue. Even at 4°C, long‐term storage (>3h) must be avoided. A method for the quantitative determination of the fat content in liver based on multiexponential analysis of the T1 relaxation process was evaluated employing mixtures of triolein with liver homogenate. Triolein is a two‐component system with T = 144 ms (α* = 62%) and T = 355 ms (α** = 38%). Finally, liver‐specific protocol conditions were defined for in vitro relaxation studies. © 1986 Academic Press, Inc.