Ifosfamide-induced alteration of technetium-99m-DMSA renal parenchymal imaging.

Renal cortical imaging with 99mTc-dimercaptosuccinic acid (DMSA) has become the imaging test of choice for the diagnosis of acute pyelonephritis. An unusual uptake pattern was observed in a child receiving chemotherapy for a bladder rhabdomyosarcoma. Chemotherapy from ifosfamide produces a specific pattern of injury to the renal tubule that alters uptake of DMSA.

Cholescintigraphy in the diagnosis of bile leak after laparoscopic cholecystectomy.

Bile leaks are a recognized complication of laparoscopic cholecystectomy (LC). Different diagnostic approaches have been employed when this condition is suspected. We present our experience with cholescintigraphy as a primary imaging technique for the detection of bile leaks. The medical records of all patients who had cholescintigraphy after LC during a 58-month period were reviewed. Patients were selected for cholescintigraphy if fever unusual abdominal pain, nausea, vomiting, or jaundice were present beyond 36 hours after LC. Bile leaks were suspected in 25 out of 744 patients (3.36%). The nuclear imaging study was true positive in 7 cases and true negative in 18 cases, for a 100 per cent sensitivity, specificity, and accuracy in the detection of bile leaks. Five patients were treated by endoscopic retrograde cholangiopancreatography with stent and/or sphincterotomy, and two patients underwent exploratory laparotomy. None of the patients who underwent endoscopic retrograde cholangiopancreatography required peritoneal drainage. We conclude that cholescintigraphy is sensitive and accurate in the diagnosis of bile leaks. Its use along with a high index of suspicion of a bile leak may prevent the development of bile peritonitis.

Technical improvements in fluorine-18-FDG PET imaging of the abdomen and pelvis.

UNLABELLED: PET tumor imaging of the abdomen and pelvis is prone to artifacts due to urinary tract activity. A new technique has been developed to reduce such artifacts and enhance study interpretation. METHODS: Thirty minutes after the injection of 18F-FDG, 500 cc 0.45% NaCl were administered intravenously over 30 min and a Foley catheter was placed in the bladder. At the start of imaging (60 min post-injection), furosemide was given (0.3 mg/kg). Prior to imaging the pelvis, the urinary catheter was clamped and saline was introduced retrograde into the bladder until full. RESULTS: This technique has been used successfully in more than 130 patients, resulting in a marked improvement in study quality and tumor detection. CONCLUSION: Hydration and administration of furosemide, along with placement of a Foley catheter in the bladder, have proven effective in eliminating image artifacts originating from the kidneys, ureters and bladder. Backfilling the bladder also provides a well-defined anatomic landmark for study interpretation.

Sudden infant death syndrome.

Sudden infant death syndrome (SIDS) is a perplexing and troubling problem for health care professionals and the community. This article discusses the epidemiology of SIDS and nursing interventions to meet the needs of families affected by SIDS.

Influence of the chemical nature of side chain at beta 108 of hemoglobin A on the modulation of the oxygen affinity by chloride ions. Low oxygen affinity variants of human hemoglobin expressed in transgenic pigs: hemoglobins Presbyterian and Yoshizuka.

Hemoglobin A (HbA) and two low oxygen affinity variants of HbA, HbPresbyterian and HbYoshizuka, were produced in transgenic pigs and purified to homogeneity by ion-exchange chromatography. These two variants contain either lysine (HbPresbyterian) or aspartic acid (HbYoshizuka) instead of the normal asparagine residue at position beta 108 in HbA. Transgenic pigs expressed these variants at a level up to 11% and were healthy. Both HbPresbyterian and HbYoshizuka exhibited low O2 affinity (P50 of 21.2 and 18.9, respectively, compared with control HbA value of 11.8 in 0.1 M NaCl, pH 7.5) and retained normal cooperativity with Hill coefficients of 2.9 and 2.5, respectively. HbPresbyterian exhibited Bohr effect comparable with HbA. In contrast, HbYoshizuka had a diminished response to changes in pH. Thus the structural basis of reduced O2 affinity of these variants appears to be distinct: the consequence of mutation at beta 108 is a function of the chemical nature of the side chain. This is further confirmed by the sensitivity of the O2 affinity of the variants to the presence of Cl-. The O2 affinity of HbYoshizuka is insensitive to changes in Cl- concentration, whereas the O2 affinity of HbPresbyterian exhibited a pronounced and dramatic chloride effect. In fact, P50 of HbPresbyterian was identical to that of HbA at very low Cl- concentrations, and the P50 increased to >40 at 0.5 M Cl-. The chloride effect was completely abolished when HbPresbyterian was stabilized at the 2,3-diphosphoglycerate pocket by interdimeric cross-linking. Molecular modeling studies demonstrate that in HbPresbyterian, Cl- can bridge the epsilon-amino group of Lys beta 108 with either the guanidino group of Arg beta 104 or the epsilon-amino group of Lys alpha 99, resulting in the stabilization of the "T" structure. The utility of these low O2 affinity hemoglobins as cell-free oxygen carriers is discussed.

Recombinant human hemoglobin: modification of the polarity of the beta-heme pocket by a valine67(E11)-->threonine mutation.

Using the mutagenesis and a gene expression system previously described [Fronticelli et al. (1991) J. Protein Chem. 10, 495-501], we have replaced Val67E11 in the distal heme pocket of the beta-chains of hemoglobin with Thr. The valine to threonine substitution is isosteric and only modifies the polarity of the beta-heme environment. The absorption and CD spectra of the resultant mutant hemoglobin were essentially the same as that of wild-type protein, indicating that the mutation did not cause any large conformational changes and that a water molecule was not coordinated to the ferrous iron atom. Equilibrium measurements of oxygen binding to the mutant indicate a 2-fold decrease in overall affinity relative to native or wild-type human hemoglobin. Thermodynamic analyses of O2 binding curves, based either on the sequential Adair model or on the MWC two-state model, indicated that the overall decrease of O2 affinity in the system was due to a lower association equilibrium constant for the intermediates of oxygenation, particularly those involved at the third ligation step. The functional characteristics of the mutant hemoglobin in either the T- or R-state were not modified greatly by the mutation; however, the Bohr effect and sensitivity to C1- were increased, suggesting a role of the intermediates of oxygenation in the modulation of these parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of human hemoglobin in transgenic swine: an approach to a blood substitute.

Many significant challenges have to be met before a clinically useful hemoglobin-based blood substitute can be developed. A major issue is the choice of a production system. Transgenic swine have several features that appear to be suited to the abundant production of human hemoglobin. Here we show that authentic human hemoglobin can be made in transgenic pigs and purified by simple ion-exchange chromatography. The purified hemoglobin can be modified for testing and use as a blood substitute.

Production of functional human hemoglobin in transgenic swine.

A construct containing the locus control region (LCR) from the human beta globin locus together with two copies of the human alpha 1 gene and a single copy of the human beta A gene was used to obtain three transgenic pigs. The transgenic pigs are healthy, not anemic, and grow at a rate comparable to non-transgenic littermates. All animals expressed the human genes. However, alpha globin was consistently expressed at higher levels than beta globin. Isolation of the human hemoglobin from both porcine hemoglobin and other non-hemoglobin proteins was accomplished by ion exchange chromatography. The purified porcine derived human hemoglobin exhibited an oxygen affinity similar to that of human derived human hemoglobin.

Down-regulation of beta-adrenergic receptors by pindolol in Gs alpha-transfected S49 cyc- murine lymphoma cells.

The role of the alpha subunit of the guanine nucleotide-binding regulatory protein that stimulates adenylyl cyclase (GS alpha) in the down-regulation of beta-adrenergic receptors by pindolol was studied in S49 cyc- cells (normally GS alpha-deficient) transfected to express functional recombinant rat GS alpha. An inducible cell line (S49 GS alpha IND) was derived from S49 cyc- cells transfected with a vector containing the full-length coding sequence of GS alpha under the inducible control of the mouse mammary tumor virus long-terminal repeat promoter. GS alpha was not detectable in S49 GS alpha IND cells by immunoblot or by ADP-ribosylation in the presence of cholera toxin and [alpha-32P]NAD. When cells were grown in 100 nM dexamethasone, isoproterenol-stimulated cyclic AMP accumulation increased within 3 h. After 15 h, GS alpha was present at a level 40-50% of that found in S49 wild-type (WT) cells as measured either by immunoblot analysis or by [alpha-32P]ADP-ribosylation. Membranes prepared from GS alpha IND cells grown in the presence of dexamethasone bound agonist with high affinity, and this binding was sensitive to guanine nucleotides. A second vector, DzbGS alpha +, contained the coding sequence of GS alpha under the constitutive regulatory control of the SV40 early promoter. This vector was introduced into cyc- cells, and the resulting cells, S49 GS alpha CST cells, expressed GS alpha at a level comparable to that found in S49 WT cells as measured by immunoblot analysis. Isoproterenol-stimulated cyclic AMP accumulation in S49 GS alpha CST cells was at least as great as in S49 WT cells. When cells were grown in the presence of dexamethasone, exposure to 50 nM pindolol for 12 h down-regulated the density of beta-adrenergic receptors in S49 WT cells to 60% of that in cells grown in the absence of pindolol, but pindolol had no effect on the density of receptors on cyc- or GS alpha IND cells. When GS alpha CST cells were exposed to 50 nM pindolol for 12 h, the density of beta-adrenergic receptors was down-regulated by the same amount as in S49 WT cells. These results suggest that GS alpha is necessary to restore the ability of pindolol to down-regulate beta-adrenergic receptors in S49 cyc- cells and that the protein must be expressed at a level comparable to that found in S49 WT cells.

Recombinant human hemoglobin: expression and refolding of beta-globin from Escherichia coli.

A plasmid analogous to the one described by Nagai and Thogersen (Nature, 309, 810-812, 1984) has been constructed for the expression of globins in E. coli. Induction with nalidixic acid produces high yields of a fusion protein, NS1-FX-beta-globin, where NS1 represents 81 residues of a flu virus protein and FX represents a blood-clotting Factor Xa recognition sequence, Ile-Glu-Gly-Arg. This fusion protein is readily solubilized in 50 mM NaOH and remains in solution when the pH is adjusted to 8.6. Under these conditions, the fusion protein is hydrolyzed by activated Factor X, giving authentic beta-globin which can be folded in the presence of cyanohemin and native alpha-chains to produce a tetrameric hemoglobin with the functional properties of natural human hemoglobin.

Expression and characterization of the long and short splice variants of GS alpha in S49 cyc- cells.

The alpha subunit of the guanine nucleotide-binding regulatory protein GS mediates stimulation of adenylyl cyclase activity. This subunit, GS alpha, exists as two molecular weight forms, termed long and short, that differ by 14 or 15 amino acids. A physiological distinction between these two forms has yet to be defined. To compare the activities of these GS alpha isoforms, long and short forms of rat GS alpha were expressed in the cyc- variant of S49 murine lymphoma cells, which is deficient in endogenous GS alpha expression. By immunoblot analysis, the level of recombinant proteins in the clones expressing the long form of GS alpha was about twice that present in the clones expressing the short form of GS alpha or in the S49 wild-type cells. Both recombinant GS alpha proteins were sensitive to cholera toxin-catalyzed ADP-ribosylation, although the short form was labeled preferentially in both recombinant and S49 wild-type cell lines. In whole-cell assays, the clones expressing the long and short forms of GS alpha and the S49 wild-type cells gave comparable responses for stimulation of cAMP accumulation after challenge with (-)-isoproterenol, cholera toxin, or forskolin. In adenylyl cyclase assays with partially purified membranes, clones expressing the long form of GS alpha gave approximately twice the levels of cAMP in response to isoproterenol, guanosine-5'-O-(3-thio)triphosphate, NaF, or forskolin, compared with membranes from the clones expressing the short form of GS alpha or the S49 wild-type cells. However, when maximal adenylyl cyclase activity was normalized to the level of GS alpha protein in S49 wild-type cells, the cAMP productions were similar between all of the cell lines. In other membrane-based assays, the long and short forms of GS alpha were also equivalent in their dose response to isoproterenol and GTP, their kinetics of guanine nucleotide exchange and GTPase activity, and the induced high and low affinity states of the beta-adrenergic receptor in response to isoproterenol. In the latter radioligand binding analysis, membranes from the two clones expressing the long form of GS alpha consistently gave a greater proportion of the agonist high affinity state; however, this variation likely reflects the greater expression levels of GS alpha in these membranes. Thus, we conclude that the long and short forms of GS alpha expressed in S49 cyc- cells are very similar in their ability to stimulate adenylyl cyclase activity and to couple to beta-adrenergic receptors.

Lymphangiomyomatosis--newer concepts in pathogenesis and management--case reports.

Lymphangiomyomatosis was first reported more than forty years ago. Although its incidence is rare, its occurrence is being increasingly recognized and has been the subject of a growing number of cases reports in recent years. This study adds 2 more cases to the file. Both cases involved young women with the characteristic symptoms of dyspnea, cough, abdominal discomfort and swelling, chest pain, and hemoptysis, with abundant formation of refractory chylous, serous ascites. Although the progression of the disease differed in each case, pulmonary function was affected in a similar way by the presence of obstructive and restrictive defects and a decrease in diffusing capacity. Underlying abnormalities were dilated lymphatics, thickened lymphatic walls, and muscular proliferation of leiomyomatous origin, leading to bronchial restriction. The authors point to the subtlety required in arriving at a differentiated diagnosis of lymphangiomyomatosis lymphangioleiomyomatosis and the difference between the two conditions. They also make particular recommendations in respect to the importance of preliminary hormone receptor tests and to the wisdom to be exercised in ligating a main lymphatic duct in the chest to control the formation of ascites. Pneumothorax, a frequent manifestation of lymphangiomyomatosis, is found to be the result of chronic air trapping due to a combination of narrowing of conducting airways and disruption of normal lung parenchyma.

Gd-DISIDA--a potential contrast agent for magnetic resonance imaging of the hepatobiliary system.

Gadolinium (Gd) labeled diisopropyliminodiacetic acid (DISIDA) was prepared by mixing a Gd solution and a DISIDA solution in appropriate proportions and at controlled pH. Optimal complexation was obtained at a Gd:DISIDA molar ratio of 1:2.5 and the pH of the final solution was 7.3 to 7.5. The complex was found to be stable both in vitro and in vivo. Gd-DISIDA (12.5 mumol/kg) was injected into mice, and T1 and T2 relaxation times of various tissues were measured and compared with those of normal tissues. Only the T1 values of the blood and the liver markedly decreased after Gd-DISIDA administration and also the reduction in T1 values depended on the dose of Gd-DISIDA. Magnetic resonance imaging of the rabbit liver showed considerable contrast enhancement at 30 minutes after administration of 12.5 mumol/kg of Gd-DISIDA.

Pulmonary artery agenesis presenting as massive hemoptysis--a case report.

Massive hemoptysis is the expectoration of approximately 600 ml of blood in twenty-four hours. Major causes of massive hemoptysis are tuberculosis, bronchiectasis, pulmonary neoplasm, fungus ball, bronchial adenomas, lung abscess, intrabronchial rupture of an aortic aneurysm, cystic fibrosis, pulmonary infarction, and pulmonary trauma. Other, less common causes include Goodpasture's syndrome, broncholiths, pulmonary varix, A-V malformation, and bleeding disorders. Agenesis of the pulmonary artery usually occurs in association with congenital cardiac anomalies, and isolated unilateral absence of the pulmonary artery is uncommon. About 10% of the patients with pulmonary artery agenesis develop inconsequential hemoptysis, but massive hemoptysis is a very rare complication of this anomaly. The following is a case report of a twenty-nine-year-old man with agenesis of the left pulmonary artery, who presented with massive hemoptysis requiring embolization and, eventually, pneumonectomy.

Comparison of gated cardiac MRI and 2D echocardiography of intracardiac neoplasms.

The gross diagnostic factors of intracardiac tumor in four patients imaged by two-dimensional echocardiography (2D echo) and magnetic resonance imaging (MRI) were compared. Three cases had left and one had a right atrial tumor, all histologically identified as myxoma. Gated cardiac MRI depicted the size, shape, and surface characteristics of the tumors more clearly than 2D echo, because MRI provides better spatial and contrast resolution. Depiction of tumor attachment was poor to good with both techniques. Both techniques were highly accurate in localizing the tumor and displaying whether it was fixed or mobile. The global field of view provided by MRI allows better definition of tumor prolapse, secondary valvular obstruction, and cardiac chamber size. This study shows that despite its early stage of development, gated cardiac MRI provides superior image quality and is complementary to 2D echo for characterization and diagnosis of intracardiac tumor.

Clinical evaluation of 360 degrees and 180 degrees data sampling techniques for transaxial SPECT thallium-201 myocardial perfusion imaging.

The most serious controversy regarding the application of transaxial SPECT technology to 201Tl myocardial perfusion imaging is the choice between 360 degrees compared with 180 degrees data sampling techniques. The present study utilized the original 360 degrees sampled raw data of 25 patients who had both SPECT 201Tl myocardial perfusion imaging and coronary angio/ventriculography for back projection reprocessing to accomplish the 360 degrees/180 degrees comparison. The results show a high incidence, 36% (9/25), of false-positive segmental perfusion abnormality and a high incidence, 24% (6/25), of moderate to severe degree of image distortion with the 180 degrees data sampled reconstructed images. These were not observed in the 360 degrees data sampled reconstructed images. The above findings confirmed our previous preliminary conclusion that even though the 180 degrees data sampling technique has the advantage of providing improved image contrast and reduction in acquisition time it is not a reliable technique and should be abandoned. The 360 degrees data sampling is the technique of choice for transaxial SPECT 201Tl myocardial perfusion imaging.