Technetium-99m-L,L-ethylenedicysteine scintigraphy in patients with renal disorders

Technetium-99m-L,L-ethylenedicysteine (99mTc-L,L-EC), a new renal imaging agent, was introduced as an alternative to 99mTc-mercaptoacetyltriglycine (MAG3). This radiopharmaceutical can be easily labelled at room temperature and has high radiochemical purity and long stability. The aim of this study was to gain clinical experience in using 99mTc-L,L-EC in normal volunteers and patients. The clearance of this radiopharmaceutical was compared with that of iodine-131 ortho-iodohippurate (OIH) in five healthy volunteers. In addition, conventional renogram and whole-body distribution of 99mTc-L,L-EC (40 min and 3 h post-injection) were evaluated in these subjects. Subsequently, ten patients with suspected obstructive nephropathy, four with renovascular disorders and two in acute renal failure were imaged. In five patients with impaired renal function both 99mTc-MAG3 and 99mTc-L,L-EC studies were performed. In each case the scintigraphic images and time/activity curves were evaluated and various semiquantitative parameters calculated and compared. No adverse effects were noted during and after 99mTc-L,L-EC scintigraphy. The mean clearance values for 99mTc-L,L-EC and 131I-OIH in volunteers were 504 and 663 ml/min respectively. The total plasma clearance of 99mTc-L,L-EC was about 75.8% of the 131I-OIH value. In volunteers the parenchymal transit time index, whole kidney transit time index and mean parenchymal transit time for 99mTc-L,L-EC were 63 s, 124 s and 175 s respectively. The mean time to peak activity was 235 s and the time from peak to 50% of peak activity was 402 s.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined rest thallium-201/stress technetium-99m-tetrofosmin SPECT: feasibility and diagnostic accuracy of a 90-minute protocol

Technetium-99m tetrofosmin is a recently developed compound that clears from background organs rapidly. Tetrofosmin has a good correlation with 201Tl. This study assesses the feasibility and diagnostic accuracy of a combined protocol involving rest 201Tl SPECT and stress imaging with 99mTc-tetrofosmin.

METHODS

Twenty-five patients (23 men, 2 women; aged 36-73 yr) with known coronary artery disease underwent the combined protocol. Twenty minutes after the resting injection of 201Tl, resting SPECT data were acquired using low-energy, high-resolution collimators. A stress test using adenosine infusion combined with low-level dynamic exercise was performed. The stress data were collected 20 min later. The reconstructed vertical long-axis, horizontal long-axis and short-axis slices were analyzed qualitatively. Analysis was carried out using nine segments of the left ventricle. The segments were reported either as fixed or reversible. The results were compared to coronary angiography results.

RESULTS

The sensitivity and specificity for the detection of diseased coronary vessels were 85% and 70% for the left anterior descending territory, respectively, 78% and 71% for the right coronary artery, and 69% and 70% for the left circumflex. Overall, the sensitivity was 80% and the specificity 70%.

CONCLUSION

Combined rest 201Tl/stress 99mTc-tetrofosmin SPECT provides a protocol of short duration which displays similar diagnostic accuracy to a protocol using tetrofosmin as a single agent.

An analysis of radiotherapy in the management of 104 patients with parotid carcinoma

A retrospective analysis was made of 104 patients with parotid carcinoma treated with radical radiotherapy between 1977 and 1986. Eighty-seven patients received postoperative radiotherapy and 17 had radiotherapy alone. The 5- and 10-year survival figures, corrected for intercurrent deaths, were 60% and 49% respectively, with primary control rates of 68% and 58%. Local control was significantly better for patients initially presenting with T1/T2 disease, but local relapse still occurred in 23% of these patients. Of 13 patients with acinic cell tumours, four developed local recurrence and a further two had metastatic disease. These patterns of relapse suggest that patients with parotid carcinoma should receive postoperative radiotherapy irrespective of disease stage or histological type.

Regulation of an eukaryotic initiation factor-2 (eIF-2) associated 67 kDa glycoprotein (p67) and its requirement in protein synthesis

The p67 mRNA level and p67 requirement in protein synthesis were studied using an animal cell (KRC-7, rat tumor hepatoma cell) in culture. p67 mRNA was present in confluent cells but disappeared almost completely from serum-starved cells. However, when PMA was added to the serum-starved cells, p67 mRNA appeared in increasing quantities. Several-fold molar excess of p67 mRNA over that present in confluent cells was detected within 2 h of PMA addition and this level remained the same during the 4 h of the experiment. p67 requirement in protein synthesis was studied using a p67 antisense DNA construct under a metallothionein gene promoter. Expression of this antisense DNA in the presence of zinc in PMA-induced serum-starved cells completely inhibited induced appearance of p67 mRNA and subsequent protein synthesis. These results suggest that p67 is regulated at the mRNA level and also that this protein factor is essential for protein synthesis.

Thermodynamic characterization of the cooperativity of 40S complex formation during the initiation of eukaryotic protein synthesis

The first step in mammalian protein synthesis is the formation of the 40S initiation complex, composed of the 40S ribosomal subunit (R), mRNA (M, here, a 10-mer oligoribonucleotide analogue containing the initiation codon), and the quaternary complex (Q, composed of eIF-2, GTP, Met-tRNA(fMet), and the ancillary protein factor Co-eIF-2C). The interdependence of the binding of R, M, and Q in forming the 40S complex is currently unclear. We have determined the thermodynamic parameters that characterize these interactions. The binary constants for R+M and Q+M were determined spectroscopically, measuring changes in the anisotropy of the fluorescence emission of 3'-fluorescein labeled M. The other binary constant, for Q+R, and the ternary constant were determined from Millipore filtration assays using radiolabeled Met-tRNA(fMet). The association constants for the binary reactions were as follows: Ka(Q,M) < or = 0.14 x 10(6) M-1, Ka(R,M) = 1.78 x 10(6) M-1, and Ka(Q,R) = 0.94 x 10(6) M-1. The binding of Q to R.M was markedly greater than that of Q to R [Ka(Q,R.M)/Ka(Q,R) > 62]. High cooperativity for this interaction occurs in either a single-site model or in lattice models for the binding of M to R. Data obtained using five other RNA 10-mers, each with the sequence altered at the AUG codon, suggest that this cooperativity is AUG dependent. The data are consistent with a scheme in which mRNA and Q bind independently to the 40S ribosome, but when the AUG codon is properly aligned with Q, a conformational change results in a 2.4 kcal/mol stabilization of the complex.

Synthesis and characterization of conjugates formed between periodate-oxidized ribonucleotides and amine-containing fluorophores

The synthesis and purification of new fluorescently labeled derivatives of GDP and ATP are described. The fluorescent groups are coupled initially through amine-containing linker arms to periodate-oxidized nucleotides. Reduction of the initial product yields primarily a six-membered morpholine-like ring. Fluorescein-labeled GDP, rhodamine-labeled GDP, and fluorescein-labeled ATP were characterized by absorbance spectroscopy and TLC. NMR and FAB-MS studies were carried out on a single nucleotide derivative formed by reacting periodate-oxidized guanosine and benzylamine with subsequent reduction to establish the modification to the ribose moiety. The synthesis of the guanosine-benzylamine conjugate led to a mixture of products that were separated. The predominant product (70%) resulted in conversion of the ribose moiety to a six-membered morpholine-like ring having no hydroxyl group, and the minor product (30%) resulted in an open ring structure having one hydroxyl. When NaCNBH3 was used as the sole reductant, only the product with the morpholine-like ring was formed. These probes were prepared for use in solution studies of the interactions of eukaryotic initiation factor-2 with other components of mammalian protein synthesis initiation.

201Tl myocardial perfusion SPET: adenosine alone or combined with dynamic exercise

201Tl myocardial perfusion single photon emission tomography (SPET) with pharmacological coronary vasodilatation using adenosine is now often used in the investigation of a patient with ischaemic heart disease (IHD). In this study, we present data from two groups of patients. Group A (n = 40) experienced 201Tl SPET with adenosine only as the pharmacological stress test, using an infusion rate of 140 micrograms kg-1 min-1. Group B patients (n = 50) had the same test combined with low-level dynamic exercise. The side effects were noted for both groups and 201Tl SPET studies were acquired for stress and redistribution images. There was a lesser degree of non-cardiac side effects in patients of group B. There was a significant difference in the haemodynamic parameters between the two groups. There was no significant difference in overall sensitivity (87% versus 90%) and specificity (84% versus 88%) in the detection of IHD between the two groups. In conclusion, addition of low-level dynamic exercise with adenosine is to be preferred to adenosine infusion alone, as this protocol is better tolerated and may enhance the detection of right coronary artery disease (sensitivity = 82% versus 90%, n.s.).

Mechanism of action of an eukaryotic initiation factor-2 (eIF-2) associated 67 kDa glycoprotein (p67) and an eIF-2 kinase (dsI)

Mechanism of regulation of eIF-2 alpha-subunit phosphorylation by dsI and p67 was studied. The results are as follows: (1) At low dsI concentration, p67 protected equimolar concentration of eIF-2. (2) At high dsI concentration, dsI efficiently phosphorylated eIF-2 alpha-subunit even when equimolar concentrations of both p67 and eIF-2 were present. Significantly increased p67 concentration was necessary to protect eIF-2 alpha-subunit at high dsI concentration. (3) dsI was also phosphorylated as it phosphorylated eIF-2 alpha-subunit. p67 inhibited both eIF-2 alpha-subunit and dsI phosphorylation similarly. (4) Although the [32P]-labelled dsI formed during the reaction could be effectively chased upon subsequent addition of excess unlabelled eIF-2 and ATP, the [32P] labelled eIF-2 formed under identical conditions, retained most of the radioactivity. (5) dsI coimmunoprecipitated with three subunit eIF-2 and p67 inhibited this coimmunoprecipitation reaction. It has been proposed: Three subunit eIF-2 and free p67 are in equilibrium with eIF-2 bound to p67 and, eIF-2.p67 complex is resistant to dsI phosphorylation. Activated dsI is already phosphorylated. At high concentration, dsI(P) can bind to free three subunit eIF-2 and form eIF-2.dsI(P) complex. dsI(P) in this complex then transfers its phosphoryl residue to eIF-2 and forms eIF-2 alpha(P) in an irreversible reaction. In a subsequent reaction, unphosphorylated dsI is autophosphorylated using [gamma 32P]-ATP and the cycle continues. Inhibition of eIF-2 alpha-subunit phosphorylation by p67 blocks this phosphorylation cycle and consequent dsI phosphorylation.

Regulation of eIF-2 alpha-subunit phosphorylation in reticulocyte lysate

An eIF-2 associated 67-kDa protein (p67) protects eIF-2 alpha-subunit from eIF-2 kinase(s) catalyzed phosphorylation and promotes protein synthesis in the presence of active eIF-2 kinase(s). p67 is a glycoprotein and contains multiple O-linked GlcNAc moieties. We have now studied the roles of hemin, p67, and the glycosyl residues on p67 in the regulation of eIF-2 alpha-subunit phosphorylation in reticulocyte lysates. The results are as follows: (i) Both hemin and p67 inhibited HRI (heme-regulated protein synthesis inhibitor) and dsI (double-stranded RNA activated protein synthesis inhibitor) catalyzed phosphorylation of eIF-2 alpha-subunit in vitro. However, only hemin, and not p67, inhibited casein kinase catalyzed phosphorylation of eIF-2 beta-subunit. (ii) Only p67, and not hemin, inhibited eIF-2 alpha-subunit phosphorylation by eIF-2 kinase(s) in reticulocyte lysate. Significant eIF-2 alpha-subunit phosphorylation was observed even in the presence of hemin when p67 in the reticulocyte lysate was removed by treatment with p67 antibodies. (iii) Reticulocyte lysate contains a p67-deglycosylase in latent form, and hemin prevents activation of this deglycosylase. In the absence of hemin, this p67-deglycosylase is activated. Once activated in the absence of hemin, the activated deglycosylase deglycosylates p67, even in the presence of hemin. This inactivates p67 and allows eIF-2 kinase to phosphorylate eIF-2 alpha-subunit and inhibit protein synthesis. Protein synthesis in reticulocyte lysate is thus regulated by two novel cascades of covalent modifications: protein deglycosylation leading to protein phosphorylation.

Angioscopy-guided training model of coronary artery anastomosis

Surgical models are proving invaluable in the training of junior surgeons or in the development of new skills by senior surgeons. We have developed a model in which coronary artery anastomoses may be performed and evaluated with an angioscope, thus facilitating development of skills.

Systemic heparinization during peripheral vascular surgery: thromboelastographic, activated coagulation time, and heparin titration monitoring

Fifteen patients (9 male, 6 female) undergoing peripheral vascular surgery were monitored during surgery for evidence of subclinical anticoagulation using the activated coagulation time (ACT), thromboelastography (TEG), and heparin titration monitoring. Assessments were made at 30-minute intervals before and after the occlusion clamp. Mean (+/- SD) ACT values preoperatively were 111 (17) seconds, and 10 minutes after 5,000 IU of heparin, the ACT was 264 (57) seconds (P < 0.001). Intraoperatively, there was a significant decline in ACT values at 30 minutes (ACT 228 [50] sec, P < 0.005) and 60 minutes (200 [46] sec, P < 0.001) postheparin. No significant difference in ACT was observed between samples drawn distally and proximally to the clamp. TEG profiles were abolished in all patients immediately following heparinization. However, in 2 patients nearly complete return of the TEG coagulation profile was observed prior to the termination of the procedure and was associated with ACT values less than 160 seconds. The heparin device was unable to accurately monitor heparin elimination at these low doses. Variability of patient response to heparinization necessitates the use of intraoperative monitoring of anticoagulation during peripheral vascular surgery.

Effect of type of resection on plasma granulocyte elastase levels following surgery for non-small cell lung carcinoma

The lung is the primary focus of complications associated with adult respiratory distress syndrome (ARDS) and increased activation of granulocytes has been implicated in the genesis of ARDS. In the present study, plasma granulocyte elastase levels were measured in 24 patients undergoing lung resection for non-small cell lung carcinoma. Pre-, peri- and post-operative assessments of plasma elastase levels were made of patients who underwent a partial resection (lobectomy, n = 13) and patients who underwent a complete lung resection (pneumonectomy, n = 11). Preoperatively, values were similar for both patient cohorts and did not differ from those of normal volunteers. However, immediately (1 h) post-operation, elastase levels in patients who had undergone pneumonectomy were significantly elevated (300% of baseline value, P < 0.005), whereas levels were unchanged in lobectomy patients. On the 1st post-operative day (POD), elastase levels had returned to normal in pneumonectomy patients, whilst lobectomy patients now exhibited increased plasma elastase levels which remained marginally increased until the time of discharge (P < 0.05). The determinants of granulocyte activation following lung resection remain to be elucidated but may potentially relate to ischemic reperfusion in patients undergoing lobectomy, or alternatively may simply reflect the extent of manipulation, compression and contusion of lung tissue.

Fate of patients with residual tumour at the bronchial resection margin

The presence of microscopic deposits of tumour cells at the bronchial resection margin (BRM) may adversely affect the prognosis of patients. Residual tumour cells were identified at the BRM in 40 (5.4%) of 735 patients who had been operated on for non-small cell lung carcinoma (NSCLC). The extent of disease was stage I in 7 (17.5%), stage II in 21 (52.5%), stage IIIa in 10 (25%) and stage IIIb in 2 (5%) patients. Malignant cells were found to have infiltrated the submucosal lymphatics in 5 (12.5%) cases and the peribronchial tissue in the remaining 35 (87.5%). Fifteen (37.5%) patients received adjuvant radiotherapy (RT). Recurrence of the disease was diagnosed in 29 (72.5%) patients after a median of 17 months (range 3-111). The recurrence was local in 17 (59%) and distant in 12 (41%). The 5-year overall actuarial survival rate was 21.6% and was not affected by RT (P = NS). Only patients with stage IIIa disease and a positive bronchial stump had a significantly reduced 5-year survival rate compared to those with a negative stump, 0% vs 17% (P < 0.001). Tumour cells at the resection margin did not affect the survival in this cohort except those with stage IIIa disease, and the addition of adjuvant RT did not significantly affect its recurrence in patients with NSCLC.

Cloning and characterization of complementary DNA encoding the eukaryotic initiation factor 2-associated 67-kDa protein (p67)

The eukaryotic initiation factor 2 (eIF-2)-associated 67-kDa glycoprotein (p67) protects eIF-2 alpha-subunit from inhibitory phosphorylation by eIF-2 kinases, such as heme-regulated inhibitor and double-stranded RNA-activated inhibitor. This promotes protein synthesis in the presence of eIF-2 kinases present in animal cells (Ray, M. K., Datta, B., Chakraborty, A., Chattopadhyay, A., Meza-Keuthen, S., and Gupta, N. K. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 539-543). In this study, the primary structure of rat p67 is determined by cDNA cloning. Based on the partial amino acid sequences of overlapping tryptic and cyanogen bromide cleaved fragments, degenerate oligonucleotides were synthesized and used as primers for the polymerase chain reaction to amplify the corresponding p67 cDNA fragment from rat liver first strand cDNA. The amplified DNA was then used as a probe to screen a rat tumor hepatoma (KRC-7) cDNA library, and a positive clone covering the entire coding region was obtained. From the cDNA sequence, an open reading frame that encodes p67 as a 480-amino acid protein with a molecular mass of 53 kilodaltons was predicted for the unglycosylated protein. The cloned cDNA was further characterized by in vitro transcription-coupled translation in micrococcal nuclease-treated reticulocyte lysate. The translated product migrated similarly to p67 in SDS-polyacrylamide gel electrophoresis and was precipitated with antibodies against p67. Northern blot analysis of rat liver poly(A)+ RNA showed a single size class (approximately 2 kilobases) of mRNA. The deduced amino acid sequence of the protein showed a highly charged N-terminal region composed of two basic polylysine blocks and an acidic aspartic acid block. The protein also exhibits significant sequence identity in the N-terminal region with human eIF-2 beta-subunit.

Purification and analysis of a human sarcoma associated antigen

S1, a heterophile antigen present on human sarcoma cell lines in culture, has been previously defined by this laboratory [1,2]. This antigen is also present in guinea-pig kidney. Purification of the antigen to homogeneity has now been achieved by a combination of ammonium sulfate fractionation, DEAE-cellulose, sephadex, high pressure liquid chromotography and affinity chromotography. S1 is a monomeric protein of 70,000 Da, as indicated by the presence of a single band on SDS-PAGE. Amino acid analysis demonstrates the prevalence of glycine, lysine and glutamic acid. Aspartic acid was found to be the N-terminal residue with further sequence of glycine-valine-alanine-glutamic acid (gly-val-ala-glut).

Long-term results in the elderly following pulmonary resection for non-small cell lung carcinoma

The long-term results of 647 patients undergoing pulmonary resection for non-small cell lung carcinoma (NSCLC) between 1980-1988 were reviewed. One hundred forty-five (22%) were elderly patients (70 years or more, group 1), with a mean age of 72.3 years (70-81) and the other 502 (18%) were younger (69 years or less, group 2) with a mean age of 61.4 (40-69) years. The male to female ratio was 4:1 in group 1 and 3:1 in group 2. The number of patients in group 2 (n = 234, 47%) who underwent pneumonectomy was significantly greater (P < 0.01), compared to group 1 (n = 47, 32%). Cardiopulmonary complications were more frequently observed in group 1 (19.3%) than in group 2 (7.4%), P < 0.05. Although cardiac complications (i.e. arrhythmias) were more common in the elderly group, pulmonary complications (retained secretions, atelectasis) occurred more commonly in the younger group. The overall hospital mortality in group 1 and group 2 was 8.9% and 5.3%, respectively (NS), and mortality following pneumonectomy in group 1 (10.6%) was similar to that of group 2 (7.6%) (NS). The 2- and 5-year overall actuarial survival rates were 61% and 30% in group 1 and 57% and 37% in group 2 (NS). Superior survival was achieved in patients in stage I of the disease in both groups. Cell type was not a determinant of long-term survival differences between the groups whereas type of operation (lobectomy) and sex (female) were.(ABSTRACT TRUNCATED AT 250 WORDS)

Bovine internal mammary artery as a conduit for coronary revascularization: long-term results

Graft patency after coronary artery bypass grafting depends largely on the choice of conduit. Because an increasing number of patients have insufficient or poor-quality autologous material, there is a need for a suitable synthetic graft that is readily available and easy to handle and that has good long-term patency. Early results suggest that the bovine internal mammary artery graft may meet these criteria. We have used a total of 26 such grafts in 18 patients. Postoperative angiography has been performed in 19 grafts in 14 patients, 3 to 23 months after operation; of these grafts, 3 are currently patent (15.8%, compared with 85.7% and 75.0% patency for native internal mammary artery and saphenous vein grafts in the same patients). We report the results of clotting studies and an analysis of lipid status. These patients do not, however, appear to represent any atypical group, either in terms of coagulopathy, native coronary artery size, or the type of vessel disease. Nevertheless, our poor results contrast markedly with the early enthusiasm reported from other centers.

Orbital granulocytic sarcomas (myeloid sarcomas) in acute nonlymphocytic leukemia

In a series of 89 patients with acute leukemia, orbital granulocytic sarcomas were observed in 7. All these patients had acute nonlymphocytic leukemia, and they were all children. The orbital involvement usually was bilateral, and the patients had proptosis, conjunctival hemorrhage, and chemosis. Morphologic, cytochemical, and immunophenotypic analyses did not show a predilection for any particular myeloid cell type. Two patients had biphenotypic leukemias with myeloid components. The ocular manifestations responded well to chemotherapy irrespective of the hematologic response.

Fatal Legionella maceachernii pneumonia in Canada

A case of pneumonia and acute tubular necrosis was caused by an initially unknown species of Legionella. The organism was later identified as Legionella maceachernii by a combination of cultural, biochemical, and serological methods along with a gas-liquid chromatographic profile.

Heparin rebound phenomenon--much ado about nothing?

Significant postoperative bleeding following open-heart surgery is often ascribed to the so-called heparin 'rebound' phenomenon and as such is treated with additional empiric doses of protamine sulphate. However, inappropriate protamine administration has been reported to be associated with acute pulmonary hypertension. The efficacy of heparin reversal was investigated in 42 patients undergoing open-heart surgery. The standard heparin bolus of 3 mg/kg body weight (4.1 IU/ml blood) administered before cardiopulmonary bypass was countered at the end of bypass using an empirical equivalent (3 mg/kg) of protamine. This regimen resulted in complete heparin neutralization (measured by the Hepcon HMS [Hemotec Inc., Englewood, CO, USA]) 15 min after protamine administration in all 42 patients, but heparin levels (0.4 IU/ml) were transiently detectable (duration less than 1 h) in six (14%) of the 42 cases 2 h later. Twenty-four hour postoperative bleeding in these patients did not differ significantly from that seen in patients who did not exhibit heparin rebound. Similarly, the thrombelastographic profiles (at 15 min and 2 h post-operation) and coagulation screen (prothrombin time, activated partial thromboplastin time, activated clotting time and platelets) did not differ significantly from those of non-rebound patients. The significance, if any, of the phenomenon of heparin rebound following cardiac surgery remains to be elucidated, and, until such time, conservative administration of protamine in response to 'rebound' is recommended.