bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of grape seed procyanidins with various proteins in relation to wine fining
Authors: Ricardo‐da‐Silva Jorge Manuel , Cheynier Veronique , Souquet Jean‐Marc , Moutounet Michel , Cabanis Jean‐Claude , Bourzeix Michel
Published: March 2007

Interactions of grape (Vitis vinifera L) seed procyanidin dimers and trimers, galloylated or not, with various proteins (poly‐L‐prolines, gelatins, casein, dried blood and grape arabinogalactan‐protein) were studied in wine‐like model solutions. Except for casein, protein‐procyanidin complexes were produced within the first 8 h of contact. All poly‐L‐prolines presented very high affinity towards grape seed procyanidins. In general, the extent of pro‐cyanidin‐protein interaction increased with the degree of procyanidin polymerisation and the rate of galloylation, and also with protein concentration.

When various protein fining treatments were applied to a young red wine, dimeric and trimeric procyanidin levels were not affected, although total phenolic levels were reduced.
Phenolics and in‐vitro degradability of protein and fibre in West African Browse
Authors: Rittner Ulrich , Reed Jess D
Published: March 2007

Relationships among soluble phenolics, soluble and insoluble proanthocyanidins (PAC), lignin, N, neutral‐detergent fibre (NDF), and in‐vitro degradability of protein and NDF were determined in 72 West African fodder trees and shrubs. Species were collected in the semi‐arid (Niger), sub‐humid (Nigeria) and humid/sub‐humid (Benin) zones. Variation among species in chemical composition and in‐vitro degradability of protein and NDF was large. Zones did not differ in mean content of phenolic compounds. Protein degradability was negatively correlated with soluble phenolics (r = −0.34, P < 0.01) and soluble PAC (r = −0.47, P < 0.001). NDF was positively correlated with soluble PAC (r = 0.44, P < 0.001), insoluble PAC (r = 0.28, P < 0.05) and lignin (r = 0.76, P < 0.001). NDF degradability was negatively correlated with soluble PAC (r = −0.40, P < 0.001) and lignin (r = −0.59, P < 0.001). Chemical composition and in‐vitro degradability along with field observations can provide useful criteria for determining the nutritive value of browse species.
Characterisation of polyclonal and monoclonal antibodies against glycinin (11S storage protein) from soya (Glycine max)
Authors: Carter Jane M , Lee Heather A , Mills E N Clare , Lambert Nigel , Chan Henry W‐S , Morgan Michael R A
Published: March 2007

Polyclonal and monoclonal antibodies have been raised against the soya (Glycine max L) 11S storage protein, glycinin. The characteristics of the antibodies have been studied using enzyme‐linked immunosorbent assay (ELISA) and immunoblotting techniques. The polyclonal antibodies showed strong recognition of the storage proteins from pea, and smaller but significant interactions with storage proteins from other seeds. Two monoclonal antibodies were virtually completely soya specific, recognising different continuous epitopes from the acidic polypeptides believed to be present on the surface of the native protein. A third monoclonal showed a much wider specificity in the ELISA, including the recognition of certain storage proteins from other seed types to a greater extent than soya. The epitope for this antibody may have been present on the surface of the native protein and was discontinuous, dependent on spatial organisation for recognition.
Rapid method for measuring thearubigins and theaflavins in black tea using C18 sorbent cartridges
Authors: Whitehead David L , Temple Catherine M
Published: March 2007

This communication describes the routine use of small inexpensive C18 cartridges for rapid separation and accurate measurement of both thearubigins (TR) and theaflavins (TF) in a liquor brewed from black tea. The slow, traditional method overestimates TR content because of interference from flavonol glycosides. Comparison is also made favourably with other methods available for estimating total TF and sometimes TR in tea.
A model for predicting black tea quality from the carotenoid and chlorophyll composition of fresh green tea leaf
Authors: Taylor Sarah , Baker David , Owuor Philip , Orchard John , Othieno Caleb , Gay Clifton
Published: March 2007

The plant pigment (carotenoid and chlorophyll) composition of fresh green leaf of tea for a selection of clones was studied in relation to the quality of black tea produced from processing the same green leaf.

The plant pigment composition of the green leaf for nine Kenyan clones was monitored by HPLC at 450 nm. Using discriminant analysis it was shown that clones could be distinguished from one another on the basis of their green leaf plant pigment composition.

Using step‐wise multiple regression analysis, a linear relationship was established between the levels of six green leaf plant pigments peak 5 (neochrome), peak 17 and 18 (isomers of lutein and/or lutein epoxide), peak 23 (chlorophyll b type compound), peak 26 (aurochrome) and peak 28 (β‐carotene)) and the quality of the manufactured black tea for the selected clones as assessed by tea tasters' evaluations. The model had an adjusted R‐square value of 0.912 and was significant at P≤ 0.05. The value of the relationship as a means of predicting black tea quality is discussed.
Effects of n‐3 polyunsaturated fatty acids on endothelial function
Authors: Stanley John
Published: March 2007

Dysfunction of the vascular endothelium is an early event in the development of cardiovascular disease and methods are now available to measure endothelial function in vivo in man. Endothelial function may have advantages as an endpoint in human nutrition intervention trials over cardiovascular risk factors. Several studies have now been published on effects of the n‐3 polyunsaturated fatty acids on endothelial function. When ingested together, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have favourable effects on vasodilation in coronary arteries, brachial arteries and the skin microcirculation. However, published studies do not agree on the effects of EPA and DHA when ingested separately. Further research is needed to resolve these disagreements and extend these observations particularly at intakes of EPA and DHA which are achievable by diet.
Study on the sensing capability of Fe‐C alloy corrosion sensing film
Authors: Luo Y. , Qiu Z. , Song S. , Dong S. , Wang H. , Yu H.
Published: March 2007

In this paper, a Fe‐C alloy corrosion sensing film was fabricated on the fiber core by PVD, PVD incorporated with electroplating, and other methods. A Light Power Test System which was composed of a LD lamp‐house, a Bare Fiber Adapter (BFA) and a light power meter was used to detect the changes of lamp‐house's output power in the corrosion process of the Fe‐C alloy film. The major factors that may have some effects on the sensing capability of the Fe‐C alloy film were analyzed. The initial results show that lamp‐house's output power increases gradually with the occurrence of Fe‐C alloy film's corrosion, which accords basically with the sensing principle of the film. There are some diversities in the sensing ability of the Fe‐C alloy film fabricated by different methods. The trend of changes of lamp‐house's output power can be used as a qualitative token of the corrosion information of the Fe‐C alloy film. These data have been used for some elementary preparations for a carbon steel Fiber Optical Corrosion Sensor (FOCS).
The first elective free flap in a cardiac transplant patient
Authors: Zuker R. M. , Phillips J. , De Haas W. G. , Al‐Qattan M. M.
Published: March 2007

A case of free fibula transfer for mandibular reconstruction in a cardiac transplant patient is described. The reconstructive microsurgeon should be aware of the special requirements of these immunosuppressed patients and flap transfer should be performed in specialized centers with the interaction of different specialties to make the procedure safe and successful. © 1995 Wiley‐Liss, Inc.
Effects of the prostacyclin analogue iloprost on patency in small arteries and veins: An experimental study in the rabbit
Authors: Salemark Lars , Knudsen Finn , Dougan Peter
Published: March 2007

Arteriotomy/intimectomy and venotomy/intimectomy were performed in the ears of 43 rabbits. Twenty were treated with iloprost given as intravenous doses of 10 μg/kg body weight (bw) administered shortly before reperfusion followed by hourly infusions (3 μg/kg b w) until 12 hrs after reperfusion. At reperfusion venous and arterial bleeding times were noted. Patency was determined at 15‐min intervals until 2 hrs after reperfusion and at 1 and 2 weeks postoperatively. As controls, 23 rabbits were given a single infusion of saline. Compared to controls, iloprost significantly prolonged arterial and venous bleeding times and significantly improved patency 2 hrs after reperfusion. One and two weeks later, however, virtually all vessels were occluded. Administered in this fashion, iloprost does not improve long‐term patency in highly traumatized small veins and arteries. © 1995 Wiley‐Liss, Inc.
Anatomic study of a new axial skin flap based on the cutaneous branch of the medial plantar artery
Authors: Zhang Gao‐Men , Syed Shamsuddin Ahmed , Tsai Tsu‐Min
Published: March 2007

A new axial skin flap based on the middle cutaneous branch of the medial plantar artery was evaluated in 33 fresh cadaver legs. The vascular pedicle of the skin flap is based on the middle cutaneous artery, its venae comitantes, and segments of the great saphenous vein, if necessary. The middle cutaneous artery is the largest cutaneous branch, arising from the medial plantar artery 2.5 cm distal to its origin. The diameter of its origin is 1.2 mm, and its pedicle is 2 cm long. The midline of the flap runs from the first web space to the heel tip. The upper and lower borders of the flap are 3 to 4 cm on either side of this line. The upper border is medial to the extensor hallucis tendon, and the lower border is medial to the abductor hallucis. Distally, the border begins 2 cm proximal to the metatarsalphalangeal joint; proximally, the border is at the middle of the medial malleolus. The flap diameter can be up to 8 × 12 cm. The middle cutaneous branch of the medial plantar artery was found in all cadaver specimens, except for one with a common trunk. The new flap design leaves the major blood supply to the foot and the plantar aponeurosis intact. It is easy to harvest and may be used either as an island flap or free flap. © 1995 Wiley‐Liss, Inc.
Microsurgical research—a personal experience
Authors: Buncke Harry J.
Published: March 2007

The author recounts his 38 years in microsurgical research from the early days of needle and instrument development to the first successful experimental and clinical microvascular transplants. Selected projects are discussed relating to microvascular thrombosis, vascular spasm and various experimental models in the rat, rabbit and rhesus monkey in an anecdotal fashion. © 1995 Wiley‐Liss, Inc.
Vascular complications after free tissue transfer
Authors: Rieck B. , Mailänder P. , Machens H. G.
Published: March 2007

Between 1981 and 1992, 631 cases of free tissue transfer were operated on at our clinic. Of these cases, 489 were reviewed for vascular complications. The aim of the study was to evaluate retrospectively possible correlations between complications and operative faults. Vascular complications occurred in 16%. By immediate operative revision 50% of the cases with a vascular complication could be salvaged. In general, earlier diagnosis and treatment of vascular complications after free tissue transfer prompted a higher success rate of the surgical revision. © 1995 Wiley‐Liss, Inc.
Vascularized omental graft to brain surface in ischemic cerebrovascular disease
Authors: Yoshioka Nobutaka , Tominaga Shinsuke , Suzuki Youichi , Yamazato Keisyo , Inui Toshihiko , Nonaka Kan‐Ichi , Wakamatu Keita
Published: March 2007

The application of vascularized omental graft for the treatment of four patients with ischemic cerebrovascular disease is presented. The superficial temporal artery and vein were used as recipient vessels, and vascular anastomosis was applied in an end‐to‐end fashion. The distal parts of the omentum were exteriorized as monitoring segments for about 1 week. Angiography and cerebral blood flow (CBF) studies were performed in all patients postoperatively. There were no major complications, and all patients showed increases of CBF and apparent clinical improvement. It is suggested that this method is effective in selected patients with ischemic cerebrovascular disease. © 1995 Wiley‐Liss, Inc.
Continuous perioperative monitoring of microcirculatory blood flow in pectoralis musculocutaneous flaps
Authors: Banic Andrej , Sigurdsson Gisli H. , Wheatley Anthony M.
Published: March 2007

Hypovolemia and hypotension in traumatized patients as well as those undergoing long‐lasting surgical procedures lead to hypoperfusion of tissues. Combined with the trauma of flap elevation and the warm ischemia during performance of the anastomoses, hypoperfusion of flap tissues may lead to flap failure. The influence of hypovolemia, ischemia and reperfusion on flap macro‐ and microcirculation was studied in an acute experiment on a new musculocutaneous pectoralis flap developed in minipigs. Using a multichannel laser Doppler system we studied, simultaneously and continuously, microcirculatory flow (MBF) in both the skin and muscle of the flap as well as in the contralateral control skin and muscle in anesthetized minipigs (n = 7). Measurements were done before and after raising the flap, after 90 min of flap ischemia, during mild to moderate hypovolemia (5%, 10%, 15%, and 20% blood loss) and during and after restoration of blood volume. Electromagnetic flowmetry was used to measure total blood flow (TBF) to the flap. All animals remained hemodynamically stable during the experiment. The flap MBF decreased by 20% in the skin and 25% in the muscle after flap elevation with no changes in the control skin and muscle. After flap ischemia and reperfusion, MBF returned to post‐elevation values while TBF showed a significant increase as compared to MBF (P<0.05). Hypovolemia caused a gradual drop in cardiac output (25%) and mean arterial pressure (40%), but both recovered above the baseline after reinfusion of shed blood. Hypovolemia also caused a 60% reduction in MBF in both flap skin and muscle, and only 20–23% in control skin and muscle (P<0.01). After reinfusion of shed blood the MBF in the flap remained 30–40% below and the TBF increased 20% over the baseline. The MBF in control skin and muscle increased more than 20% over baseline (P<0.01). It was concluded that MBF in flap skin and muscle decreased by approximately 20–25% as a consequence of flap elevation, while central parameters remained normal. It was shown that even during moderate hypovolemia, MBF in the flap might decrease to critical levels. We suggest that intensive monitoring of central hemodynamics and continuous LDF monitoring of the flap during and after surgery should be performed in order to restore the blood volume expeditiously and prevent irreversible damage to flap tissues. © 1995 Wiley‐Liss, Inc.
Sympathetic blockade of isolated rat hindlimbs by intra‐arterial guanethidine: The effect on blood flow and arterial‐venous shunting
Authors: McCarty Michael E. , Grossi Eugene A. , Cutting Court , Prevel Christopher D. , Elluru Raguram , Eppley Barry L.
Published: March 2007

In order to improve the understanding of the role of sympathetic nerve degeneration in reimplantation failure, the hindlimbs of eight rats (Group I) underwent near‐complete amputation. The soft tissues of the hindlimb were transected at the proximal thigh with the femoral artery, vein and femur left intact. The femoral vessels were clamped and guanethidine was infused into a branch of the femoral artery of the right leg of each animal, while saline was injected into the left leg. The clamps were removed after 15 minutes. A baseline preoperative injection of radiolabeled microspheres was made, and subsequent injections at 6, 12, 18, and 24 hours postoperation. Twelve rats (Group II) were then used to assess the amount of arterial‐venous shunting preoperatively (n = 6) and at 18 hours postoperation (n = 6), by venous sampling. Blood flow to both limbs increased postoperation, but there was significantly more flow in the guanethidine treated limb at 18 and 24 hours postoperation. The amount of shunting was approximately 50% in both limbs at 18 hours, as compared to 10% preoperation. These results highlight the potential benefit of guanethidine and other sympathetic blocking agents in reimplantation to increase blood flow, decrease tissue ischemia and increase anastomotic patency rates. They also suggest that sympathetic nerve degeneration did not affect the volume of arterial‐venous shunting in this model, but the difference in blood flow was likely due to arteriolar vasospasm. Further study is needed to elucidate the clinical significance of sympathetic nerve degeneration in reimplantation failure. © 1995 Wiley‐Liss, Inc.
Modified crush‐avulsion anastomosis model on the rat femoral vein
Authors: Fu Kaiding , Izquierdo Ricardo , Hubbard Thomas , Fareed Jawed
Published: March 2007

A crush‐avulsion anastomosis model was established on the rat femoral vein. Saline or heparin was used as a luminal topical agent and was allowed to contact the damaged endothelium for 10 min. Patency and coagulation parameters were investigated for 1 week. The heparin treated group had a patency rate of 93% at 1 hr vs. 13% for the saline treated group (P<0.001). At 7 days, the heparin treated group had an 87% patency vs. 7% for the saline‐treated group (P<0.001). Scanning electron micrography (SEM) provided evidence of the deposition of the components of early thrombosis in the crushed venous wall. In contrast, the SEM of the heparin treated group shows a paucity of any evidence of thrombus. These results indicate that the rat vein crush‐avulsion model is a reliable and reproducible thrombosis model with low patency. The methods used with the topical agent may improve the patency rate in crush avulsion injuries. © 1995 Wiley‐Liss, Inc.
Aneurysms of the digital artery: A review and report of three cases
Authors: Yajima Hiroshi , Tamai Susumu , Ono Hiroshi
Published: March 2007

Aneurysms of the digital artery are rare. Since 1980, we have treated three traumatic aneurysms of the digital artery. There were two lesions of the common palmar digital artery and one of the ulnar pollicis artery. One case was caused by a traumatic laceration with a kitchen knife, and two cases were caused by repetitive microtrauma. On histologic examination, there were two true aneurysms and one false aneurysm. Two cases were treated by excision only, and one case was treated by excision and reanastomosis. The operating microscope was useful during neurolysis, excision of the aneurysm, and vascular anastomosis. © 1995 Wiley‐Liss, Inc.
Evaluation of the effectiveness of sensory reeducation following digital replantation and revascularization
Authors: Shieh Shyh‐Jou , Chiu Haw‐Yen , Lee Jing‐Wei , Hsu Hsiu‐Yun
Published: March 2007

Sensory recovery following digital replantation plays an important role in the restoration of hand function. Twelve patients with twenty‐four replanted or revascularized digits were randomly selected to enter a program of sensory reeducation, and another 15 patients with 22 replanted or revascularized digits were selected as controls who did not receive sensory reeducation. A moving two‐point discrimination and a Semmes‐Weinstein pressure threshold test were evaluated for monitoring the sensory recovery. The period of sensory reeducation was 18.83 weeks on average, and the mean follow‐up time was 11.94 months. The group that received sensory reeducation significantly improved to a better degree of moving two‐point discrimination and Semmes‐Weinstein threshold level by both univariate and multiple regression analysis. We suggest that sensory reeducation should be an integral part of the postoperative rehabilitation protocol following digital replantation and revascularization. © 1995 Wiley‐Liss, Inc.
Immunosuppressive effect of monoclonal antibodies to ICAM‐1 and LFA‐1 on peripheral nerve allograft in mice
Authors: Nakao Yasushi , Mackinnon Susan E. , Strasberg Suzanne R. , Hertl M. Catherine , Isobe Mitsuaki , Susskind Brian M. , Mohanakumar T. , Hunter Daniel A.
Published: March 2007

This study evaluated the immunosuppressive effect of monoclonal antibodies against cell surface molecules in a murine peripheral nerve allograft model. After nerve allografting, 18 recipients were treated with both anti‐intercellular adhesion molecule‐1 (ICAM‐1) and anti‐lymphocyte function‐associated molecule‐1 (LFA‐1) monoclonal antibodies in low or high dose. Nerve allografts were harvested at 8 weeks for histologic and morphometric evaluation. Recipients were subsequently challenged with skin grafts at 9 weeks and a cytotoxic assay at 12 weeks. The majority of the antibody‐treated allografts (13 of 18) showed excellent regeneration comparable to the autografts with preservation of the normal nerve architecture and scant cellular infiltrate. All untreated allografts demonstrated severe structural disorganization with cellular infiltrate consistent with acute rejection. In the high dose group, the mean skin graft survival time from nerve donor mice, but not third‐party mice, was significantly prolonged. (17.5 vs. 11.3 days). Similarly, the cytotoxic activity against nerve donor alloantigen was significantly suppressed. These preliminary findings suggest that antibody therapy alone can facilitate nerve regeneration in a murine nerve allograft model. © 1995 Wiley‐Liss, Inc.
Nerve regeneration in different types of grafts: Experimental Study in Rabbits
Authors: Amillo Santiago , Yáñez Roberto , Barrios Raúl H.
Published: March 2007

The nerve regeneration patterns of five different types of grafts were studied in 40 rabbits. Conventional nerve autografts, vascularized nerve autografts, fresh nerve allografts, frozen nerve allografts, and muscle autografts were sutured to a 1.5 cm gap in the sciatic nerve and compared with normal nerves and nerves with a 3 cm gap. Regeneration was evaluated by means of electromyography, light and electron microscopy. Quantitative data from morphometric analysis of axonal diameter and myelination were statistical‐lyanalyzed. Results 5 months after grafting showed no significant differences between the conventional and vascularized nerve autografts. There were no significant differences between frozen nerve allografts and muscle autografts. The best regeneration was achieved with autografts. © 1995 Wiley‐Liss, Inc.
The NMR diagnosis of cerebral tumors
Authors: Bydder G. M. , Pennock J. M. , Steiner R. E. , Orr J. S. , Bailes D. R. , Young I. R.
Published: March 2007

The results of NMR examinations in 52 patients with histological or clinical diagnoses of cerebral tumor are reviewed. An increase in relaxation time was recognized in all tumors but problems were experienced in distinguishing the margin of tumors from surrounding edema. Mass effects were well demonstrated as a result of the high level of gray‐white matter contrast available with inversion‐recovery sequences and the use of coronal and sagittal imaging planes. In general repeated FID sequences were less sensitive in detecting tumors than inversion‐recovery or spin‐echo squences. Periventricular edema was well demonstrated with spin‐echo sequences and was of importance in recognizing acute or subacute hydrocephalus. Radiation therapy was associated with increased relaxation times particularly within white matter. Problems in the recognition of tumor recurrence following treatment are outlined. The opportunities and challenges that NMR imaging is now providing for physicists and radiologists are discussed.

Contents. Introduction. Patients and methods. Results Normal appearances. Benign tumors. Malignant tumors. Diagnostic features of tumors. The appearance of the tumor. Peritumoral edema. Mass effects and displacements. Hydrocephalus. The comparative sensitivity of different pulse sequences. Differentiation of tumor types. Differential diagnosis between tumors and other conditions. Effects of treatment. Comparison with X‐ray CT. Discussion. The physical basis for increased relaxation times. Volume scanning. Multislice imaging. Paramagnetic contrast agents. Tissue characterization. Particular aspects of childhood tumors. Epilepsy. Response to therapy and detection of recurrence. Summary.
Magnet field profiling: Analysis and correcting coil design
Authors: Roméo Françoise , Hoult D. I.
Published: March 2007

A full mathematical framework for the analysis and production of localized magnetic field profiles is presented. Of primary use in the production of highly homogeneous fields for nuclear magnetic resonance studies, the paper details the analysis of fields in terms of spherical harmonics, describes how field plotting in the appropriate manner may be used to obtain a direct measure of which harmonics are present, and shows how to combine basic “building blocks” to produce the various lower‐order zonal and tesseral harmonics. “Building blocks” described include coils, arcs, and sinusoids of current as well as rings and arcs of steel. The use of shaped magnets is also briefly mentioned. Attention is drawn to the presence, in high‐order designs, of possibly dominant lower orders of harmonics created by errors in fabrication. The goal of the paper is to present a design philosophy, backed by the appropriate mathematics, which is applicable to the variety of situations encountered in magnet design. Practical examples of correcting coils and “shims” are also given.
metabolic recovery after exercise and the assessment of mitochondrial function in Vivo in human skeletal muscle by means of 31P NMR
Authors: Arnold D. L. , Matthews P. M. , Radda G. K.
Published: March 2007

It has been suggested that the rate of phosphocreatine resynthesis after exercise is an index of mitochondrial oxidative metabolism in intact muscle. To investigate this hypothesis, the time courses of metabolite recovery following mild and more severe dynamic exercise of human forearm muscle were compared by means of 31P NMR. Severe exercise resulted in greater net hydrolysis of phosphocreatine and greater intracellular acidosis than light exercise. The rate of phosphocreatine resynthesis was significantly slower during recovery from the more severe exercise. To explain this it was noted that, as a consequence of the high activity of creatine kinase in the sarcoplasm, the [phosphocreatine] at any time is a function of the intracellular pH. Calculations demonstrate that the difference between rates of phosphocreatine recovery after the two exercise protocols was primarily determined by the rates of recovery of the intracellular pH to normal rest values. It is concluded that the calculated rate of recovery of the cytosolic free [ADP] to its pre‐exercise concentration may provide a more specific measure of mitochondrial oxidative activity.
Measurement of Spin‐Lattice Relaxation Times in Double Spin‐Echo Imaging
Authors: Lin Max S.
Published: March 2007

Calculation of tissue T1 in double spin‐echo imaging (90°–T‐180°–2T‐180°) using two repetition times (b1 and b2) has entailed an approximation that ignores the two 180° pulses. The theoretical consequence of the simplification is to overestimate T1 with a fractional error that increases with increasing T1 faster than linearly in a manner dependent on the sequence parameters. With b1, b2, and T as parameters, the theory gives a family of curves relating T1 to the predicted ratio of signals acquired at b2 versus b1 intervals. Tissue T1 can be determined from the observed signal ratio with no approximation. Consideration of noise effect on the precision of T1 so determined favors the use, within limits, of higher b2/b1 ratio for the same b1 + b2 time. At constant b2/b1, using longer b1 + b2 permits wider range of T1 to be measurable with a specified minimum precision.
Determinants of Proton Relaxation Rates in Tissue
Authors: Koenig Seymour H. , Brown Rodney D.
Published: March 2007

It is well established that the longitudinal magnetic relaxation rate of solvent water protons, 1/T1, increases markedly in homogeneous protein solutions as the magnetic field is reduced well below the traditional NMR range. For a 5% solution of protein of 105 Da, for example, 1/T1 increases from about 50% above the pure water rate of 20 MHz to five times the water rate at 0.01 MHz. For tissue, including blood, the behavior is similar. Data for blood show that extracellular water has ready access to the hemoglobin inside red blood cells, which causes the enhanced relaxation. The extent to which cell water can sample the spatial structure of soft tissue, and how this structure influences relaxation rates, is as yet unknown. Nonetheless, the relaxation data for tissue can be accommodated within the conceptual framework developed earlier for analyzing homogeneous solutions of diamagnetic proteins. The variation of 1/T1 with field differs among tissues, and its magnitude at a given field can vary by more than a factor of three, far more than does the water content of the tissues. Solute complexes of paramagnetic ions with macromolecules, which increase the relaxation rates of solvent protons, can be introduced intravenously in tissue. They are known to accumulate in specific organs, and therefore have potential utility as contrast‐enhancing agents in NMR imaging. Mn2+ and Gd3+, for example, produce characteristic dependences of 1/T1 on magnetic field that vary with the chemical state of the agent. The possibility exists, therefore, for monitoring the in vivo biochemistry of these agents.
Magnetic field dependence of proton relaxation rates in tissue with added Mn2+: Rabbit liver and kidney
Authors: Koening Seymour H. , Brown Rodney D. , Goldstein Edward J. , Burnett Keith R. , Wolf Gerald L.
Published: March 2007

Since contrast in magnetic resonance imaging (MRI) is so sensitive to the magnetic relaxation rates of tissue protons, the use of paramagnetic ions to alter contrast in a tissue‐specific fashion is an alluring prospect. The influence of these ions on the proton relaxation rates in homogeneous solutions is known to vary dramatically according to whether the ions are present as hydrated aquoions, in solute chelate, or immobilized in macromolecules. In tissue, there is the additional complication of access of water to the ions. In the present study, Mn2+ ions were introduced into rabbits both orally and intravenously in various chemical complexes. Accumulation of these ions in rabbit liver is demonstrated here, qualitatively, by MRI. The quantitation of the change in relaxation rates is investigated in excised samples of liver and kidney by study of the magnetic field dependence (dispersion) of the relaxation rates of the protons (NMRD profiles) of tissue water. Results are presented for several sets of experiments, including doseresponse data for weakly chelated Mn2+ and time‐response data for free and complexed Mn2+. The general findings are that, for liver, the response (the increment in the NMRD profile) is relatively rapid (<2 m); that it is relatively independent of how, or in what form, the Mn2+ is introduced; that it persists for several hours (at least); and that it saturates with increasing body load of Mn2+. Moreover, from the form of the NMRD profiles of liver, it is clear that the Mn2+ ions are bound irrotationally, perhaps to cell membrane, and, when introduced in chelated form, can become separated even from strongly associated chelate complexes. For kidney, the results are qualitatively similar, though different in detail.
The use of agar gel as a basic reference material for calibrating relaxation times and imaging parameters
Authors: Vre R.Mathur‐De , Grimee R. , Parmentier F. , Binet J.
Published: March 2007

The relaxation properties of agar gels render it a potentially useful basic reference material for calibrating the NMR equipment. The T1 and T2 values are close to the values observed for most biological tissues; they are stable and can be varied by controlling the concentration of MnCl2. The temperature, concentration, and volume dependence of T1 and T2 were studied.
Sensitive‐volume localization for in vivo NMR using heteronuclear spin‐echo pulse sequences
Authors: Robin Bendall M. , Pegg David T.
Published: March 2007

Heteronuclear spin‐echo techniques, which require the application of an inversion pulse on the second heteronucleus, may be applied with inhomogeneous rf coils such as surface coils. There are important applications in vivo including the detection of 13C‐ labeled and 15N‐labeled metabolites in the 1H NMR spectrum. Using a depth pulse scheme for the 1H spin‐echo sequence, and particular single or composite 13C pulses, two sensitive volumes are generated by the 1H and the 13C rf coils and signal is only obtained from the region of overlap between the two sensitive volumes. This method of signal localization for in vivo applications can be extended to 1H homonuclear editing and selective polarization‐transfer techniques. The off‐resonance characteristics of several different composite pulses are explored.
Performance evaluation of whole‐body NMR scanner antenna systems
Authors: Sergiadis George
Published: March 2007

Whole‐body NMR imaging antennas (probes) are strongly affected by the inevitable magnetic and controllable dielectric losses. Using a convenient parallelepiped model, the magnetic losses are evaluated. By introducing the “ideal power gain,” the best possible antenna performance is delimited as a function of the frequency and the patient examined. By using a cylindrical model and introducing the “electrostatic quality factor” (EQF), the dielectric loss of any antenna can be estimated. With the help of the wideband field measurer described, a simple experimental arrangement, and the analysis developed, the performance of whole‐body NMR antennas can be compared and/or evaluated. An example is given for the application of this model at 6.4, 21, and 64 MHz for three typical patients.
Identification and characterization of tissues by T2‐selective whole‐body proton NMR imaging
Authors: Gersonde K. , Tolxdorff T. , Felsberg L.
Published: March 2007

T2‐selective proton imaging at 10 MHz is based on a Carr‐Purcell‐Meiboom‐Gill pulse sequence with at least 36 echoes and 2τ ≃ 6 ms employing the projection reconstruction technique. The transverse magnetization decay of the volume elements is multiexponential composed of up to three monoexponential T2 components. The T2 values are arranged in T2 histograms which are slice specific. T2 windows are defined in the T2 histogram and used for imaging and for selecting T2 values which are assigned to proton classes and tissues. Tissue characterization is based on the visualization of differences in T2 behavior. The T2 values are transformed into 256 gray levels or, by use of a red‐green‐blue lookup table, into a rainbow code. Two display techniques have been developed and implemented in the RWTH Aachen Magnetic Resonance Software System (RAMSES): (i) for nonselective T2 imaging with secondary T2 selection and encoding of molecular classes on the basis of T2 values; (ii) for T2‐selective imaging by employing combined primary and secondary T2 selection and encoding particular tissues and variations therein. The tissues can be identified by selecting different classes of molecules, like water, lipids, and proteins, when shifting the primary T2 window on the T2 axis of the T2 histogram.
A Magnetic Shield for Large‐Bore, High Field Magnets
Authors: Ewing James R. , Timms Williams , Williams J. E. C. , Welch K. M. A.
Published: March 2007

An effective shield for the de fringing field produced by a large‐bore, high field magnet intended for imaging and in vivo spectroscopy is presented. While limiting the extent of fringe fields, the shield has little effect on the homogeneity of the central field of the magnet. The effect of institutional safety policies as well as the exigencies of patient access in a hospital environment are emphasized as influences on the planning of an in vivo NMR installation.© 1985 Academic Press,Inc.
Nuclear Magnetic Resonance Probes for Investigations of the Virus‐Cell Interactions
Authors: Valensin Gianni , Valensin Pier E.
Published: March 2007

Measuring the NMR relaxation parameters of selectively excited protons within molecules bound to the cell membrane was shown to provide a profitable way of looking at the viruscell interaction. Such approach made it possible to delineate the virus adsorption to human red blood cells by using the NMR features of the cytoskeleton inhibitor colchicine.© 1985 Academic Press,Inc.
A Novel Double‐Surface Coil Approach to Phosphorus‐31 Spectroscopy: A Study of Hemispheric Brain Injury in the Rat
Authors: Chew Wil M. , Moseley Michael E. , Nishimura Merry C. , Hashimoto Takahiro , Pitts Larry H. , James Thomas L.
Published: March 2007

An arrangement of two surface coils was devised to allow phosphours‐31 (31P) NMR spectroscopy of a localized hemispheric brain injury model in the rat. Two elliptical (8×12mm) surface coils are placed parallel to each other (3 mm apart) over each side of the rat head. Spectra are collected from either the normal or the injured side of the head using the appropriate surface coil. A passive detuning method was used to eliminate unwanted coil‐coil interactions. 31P imaging results with the two coils on phantoms show excellent isolation (6% signal overlap) between the two coils. The two‐coil set up was then used to follow a time course of injury from the hemispheric injury model.© 1985 Academic Press,Inc.
Nuclear magnetic resonance imaging characterization of a rat mammary tumor
Authors: Osbakken Mary D. , Kreider John W. , Taczanowsky Pauline
Published: March 2007

Intradermal injection (1 × 106 cells) of rat mammary adenocarcinoma (13762A) was made in the back skin in 12 rats. Tumor growth and characterization was followed with nuclear magnetic resonance imaging (NMRI) in 9 rats (3 rats died before completion of the study) at 3, 4, and 5 weeks after injection, using spin echo, inversion‐recovery, and calculated T1 techniques. Three rats were sacrificed after each of the three imaging periods for histological studies designed to distinguish solid tumor mass from necrosis. Qualitative NMR imaging T1 values increased as the tumors increased in size as evidenced by a progressive decrease in image intensity compared to the surrounding tissues on the T1 weighted images. Calculated T1 values also increased as the tumors aged (Week 3 = 0.3 ± 0.11; Week 4 = 0.45 ± 0.07; Week 5 = 0.42 ± 0.03). Planimetry of tumor areas on histological sections showed that as tumors increased in size, the ratio of necrotic area to solid tumor area increased (Week 3 = 0.3 ± 0.11; Week 4 = 0.45 ± 0.07; Week 5 = 0.51 ± 0.05). These findings indicate that the progressive increase in T1 observed on NMR images may be secondary to the increasing degree of necrosis, with a resultant change in water content and state. Thus, the range of T1 values observed in tumors of similar type may be due to change in tumor physiology and anatomy as tumor growth progresses. In conclusion, careful correlation of histological data with NMR image data is necessary before NMR imaging can be used to provide reliable noninvasive histological information concerning tumor pathology. © 1986 Academic Press, Inc.
Energetics of human muscle: Exercise‐induced ATP depletion
Authors: Taylor D. J. , Styles P. , Matthews P. M. , Arnold D. A. , Gadian D. G. , Bore P. , Radda G. K.
Published: March 2007

The energetics of human muscle have been investigated in vivo during and after fatiguing aerobic, dynamic exercise. Changes in cytoplasmic pH and concentrations of phosphocreatine, ATP and Pi were followed using 31P nuclear magnetic resonance spectroscopy. ATP was significantly depleted in 6 out of 12 experiments and in these 6 experiments decreased to 55 ± 5% of the pre‐exercise concentration. Depleted muscle had a lower phosphocreatine concentration (17 ± 5% of resting value) and lower pH (6.12 ± 0.04) than fatigued muscle in which ATP loss was not observed (26 ± 5% for phosphocreatine and 6.37 ± 0.09 for pH). The free energy of hydrolysis of ATP was not significantly different in the two groups and was also similar in exhausted and nonexhausted muscle. Loss of ATP was associated with altered recovery of the muscle: [phosphocreatine], [Pi], and pH returned more slowly to their pre‐exercise values and the initial rate of oxidative phosphorylation was diminished. The restitution of [ATP] to its pre‐exercise value was much slower than that of the other metabolites. © 1986 Academic Press, Inc.
Quantification of pulsatile flow in MRI by an analysis of T2 changes in ECG‐gated multiecho experiments
Authors: Mueller E. , Deimling M. , Reinhardt E. R.
Published: March 2007

The transport of magnetization by fluid flow through thin slices in MRI causes changes in the measured T2 relaxation time. This effect is used to compute velocity values at several different times relative to the cardiac cycle using data in ECG‐gated multiecho experiments which last a few minutes. © 1986 Academic Press, Inc.
A gross morphologic, histologic, hematologic, and blood chemistry study of adult and neonatal mice chronically exposed to high magnetic fields
Authors: Osbakken Mary , Griffith James , Taczanowsky Pauline
Published: March 2007

Six sets of Charles River CD‐1 mice (3 sets of adults and 3 sets of offspring: 156 mice total) were raised for varying times (360 h over 1 month to 624 h over 3 months) in a 1.89‐T magnetic field. Each set was divided into 3 groups: control group raised in the animal facility (Control); control group raised in the magnet room but not in the magner (Magnet‐Controls); experimental group raised in the magnet (Magnet). At the end of each predefined exposure period, the mice were euthanized and studied. Body and organ weights were lower in 3 of 6 sets in the Magnet groups when compared to Control groups, but they were not significantly different from age matched, sex matched Magnet‐Controls. This seems to indicate that the decreased growth of mice was due to the laboratory envi‐ronment surrounding the magnet, when compared to the animal facility environment, rather than to magnetic field effects. No consistent differences were found in gross and microscopic morphology, hematocrit and white blood cell counts, plasma creatine phosphokinase, lactie dehydrogenase, cholesterol, tricylceride, or protein concentrations in Magnet groups compared to the two control groups. © 1986 Academic Press, Inc.
Two‐point T1 measurement: Wide‐coverage optimizations by stochastic simulations
Authors: Lin Max S. , Fletcher James W. , Donati Robert M.
Published: March 2007

Stochastic reliability of T1 measurement from image signal ratios is examined in the ideal case by stochastic simulations in the context of wide‐coverage optimizations. Precise measurements prove to be accurate, and accurate ones precise. Sign‐preserved inversion‐recovery (IR)/non‐IR techniques are the best ration method, reciprocal non‐IR/IR ones being equivalent, but inconvenient. Wide‐coverage optima are relatively unsharp. Suggested guidelines for covering the 150‐ to 1500‐ms T1 band are minimal relevant TE; T1 about 400 ms; effective repetition times about in the ratio, TR2(IR)/TR1 (non‐IR) = 2.5–3.0, and in a sum as long as possible up to about TR1 + TR2 = 3.5–4.0 s; signal‐averaging after and only after TR1 + TR2 has been lengthened to the said region. Also suggested are different guidelines for covering T1 bands, 120–1200 and 200–1800 ms. Typically, precisions and accuracies improve linearly or faster with increasing S/N and (S/N)2, respectively. Unnecessarily high pixel resolutions or thin slicings exact great penalties in accuracies. Progressively shortening TR1 eventually transforms a wide coverage into a sharp targeting with small potential gains in a narrow T1 locality and large compromises almost everywhere else. The simulations yield an insight into applicabilities of standard error propagation analyses in two‐point T1 measurement. © 1986 Academic Press, Inc.
Multipurpose NMR imaging using stimulated echoes
Authors: Matthaei D. , Frahm J. , Haase A. , Merboldt K. D. , Hänicke W.
Published: March 2007

STEAM (stimulated‐echo acquisition mode) imaging techniques recently introduced by the authors are demonstrated to provide a versatile tool for improving the parametric specificity in NMR imaging. Stimulated echoes can be excited by a sequence of at least three rf pulses with flip angles of 90° or less. The main characteristics of the STEAM method are based on the great functional flexibility of an imaging sequence comprising three rf pulses unequal to 180° and three intervals prior to acquisition of the data. Major advantages are the easy access to contiguous multiplanar images, to CHESS (chemical‐shift‐selective) images, and to T1 information. Moreover, the rf power deposition is considerably reduced as compared to spin‐echo NMR imaging sequences. Here first in vivo results on human extremities are presented including contiguous multislice images, multiple CHESS images, and spin‐lattice relaxation time images calculated from a series of simultaneously recorded T1‐weighted STEAM images. © 1986 Academic Press, Inc.
An in vivo31P NMR study of cerebral hypoxic hypoxia in rats
Authors: Litt Lawrence , González‐Méndez Ricardo , Weinstein Philip R. , Severinghaus John W. , Hamilton William K. , Shuleshko Julia , Murphy‐Boesch Joseph , James Thomas L.
Published: March 2007

Twenty minutes of hypoxic hypoxia in five anesthetized rats reversibly reduced cerebral PCr and pH while ATP stayed constant. Complete metabolic and neurologic recovery occurred after oxygen was restored. Careful control of physiological parameters resulted in metabolite changes that were the same, within errors, in each animal. © 1986 Academic Press, Inc.
Metabolic consequences of anoxia in the isolated, perfused guinea pig heart: Anaerobic metabolism of endogenous amino acids
Authors: Brainard James R. , Hoekenga David E. , Hutson Judith Y.
Published: March 2007

The metabolic consequences of anoxia in the isolated, perfused guinea pig heart were examined by 13C NMR spectroscopy of 13C‐labeled metabolites in situ. Upon addition of [3‐13C]pyruvate to the perfusate during normoxic conditions, label is detected in several metabolites, including alanine (C3), glutamate (C2, C3, and C4), and aspartate (C2 and C3), reaching steady state levels 10–15 min after the labeled precursor reaches the heart. During anoxia, the label in glutamate and aspartate decreases and label appears in C2(3) of succinate. This real‐time observation demonstrates that in the isolated intact heart, anaerobic metabolism of the amino acids aspartate and glutamate to succinate occurs. These pathways, which were first noted to occur in skeletal muscle of diving mammals, may provide a mechanism supplemental to glycolysis for the production of nucleoside triphosphates during periods of anoxia. © 1986 Academic Press, Inc.
Improved formulae for signal amplitudes in repeated NMR sequences: Applications in NMR imaging
Authors: Sperber G. O. , Ericsson A. , Hemmingsson A. , Jung B. , Thuomas K.‐Å.
Published: March 2007

An improved formalism describing the dependence of the signal strength on relaxation times and spin densities in pulsed nuclear magnetic resonance experiments is presented. It is especially applicable to repetitive experiments such as occur in imaging applications. Essentially, it includes long‐time spin coherence effects not considered in the algorithms usually adopted. Also, some generalizations of classical concepts are made. Validity criteria are studied using numerical simulations. The algorithm assumes a relatively inhomogeneous main magnetic field, but the computer simulations indicate that the inhomogeneity normally present in magnetic resonance imagers is sufficient. The simulations also indicate that the field gradient pulses applied in the spatial encoding procedure do not necessarily interfere seriously with the validity of the formulae, but complicate the choice of optimal formula and may in some circumstances prevent the spin system from reaching a steady state. © 1986 Academic Press, Inc.