Biomechanical analysis of the effect of changing patient-handling technique.

The objective of the study was to assess the changes in the mechanical load on the low-back when shifting from a self-chosen to a recommended patient-handling technique. Nine female health care workers without formal education in patient-handling carried out 8 different tasks involving moving, turning and lifting situations. By means of a dynamic 3D biomechanical model of the lower part of the body, peak torque, compression and shear forces at the L4/L5 joint were compared using the two different patient-handling techniques. In 5 of the 8 tasks, a significant reduction was observed in spinal loading. Application of the recommended technique decreased the compression value significantly for all tasks with a mean value above 3000 N. For the two tasks with the highest compression values when using the self-chosen technique (4223, 4446 N), the loading was reduced with 36% and 25%, respectively. If the principles behind the recommended technique are implemented and maintained, a decrease in the risk of low-back disorders during patient-handling should thus be expected.

Diagnostic dilemmas in parathyroid scintigraphy.

PURPOSE: Tc-99m MIBI scintigraphy can be useful for preoperative localization of parathyroid adenomas, despite its limited sensitivity. To refine interpretation, the authors conducted prospective reviews of the scintigraphic studies of patients with concomitant thyroid nodular disease and revised the false-negative and false-positive results. MATERIALS AND METHODS: Seventy-seven patients with primary hyperparathyroidism, associated with a solitary parathyroid adenoma, underwent dual-phase MIBI scintigraphy with subsequent injection of Tc-99m pertechnetate before surgery. The false-negative and false-positive scintigraphic findings were identified and revised. RESULTS: After surgery, revision of 19 false-negative scans of the total 77 studies led to the demonstration of an adenoma in seven patients. In five of the seven studies, the adenoma had been overlooked as a result of rapid tracer washout. Two additional small focal lesions would have also been identified if subtraction had been used for differences in contour of the MIBI and pertechnetate images. Four studies were interpreted falsely as abnormal, leading to a positive predictive value of 91%; three were associated with thyroid nodular disease. CONCLUSIONS: Differential washout of MIBI from thyroid and parathyroid tissue is not universal. When MIBI is washed out rapidly from parathyroid adenomas, subtraction of a thyroid image should be performed and differences in contour delineated to localize the adenoma accurately. Some, but not all, thyroid lesions account for the false-positive findings.

Tc-99m mercaptoacetyltriglycine clearance: comparison of camera-assisted methods.

PURPOSE: To compare the accuracy of three camera-assisted methods for the measurement of Tc-99m mercaptoacetyltriglycine (MAG3) clearance. MATERIALS AND METHODS: MAG3 renal scintigraphy was performed in 21 adults with different degrees of renal function. Posterior views were obtained that included the heart and the kidneys in the camera field of view. The syringe for injection was imaged before and after injection. Blood samples were drawn 24 and 43 minutes after injection and plasma radioactivity was measured. Three camera-assisted techniques to measure MAG3 clearance were tested: 1) Biexponential fitting of the left ventricular curve, normalized to plasma activity at 24 minutes; 2) calculation of clearance by relating the integral of the plasma curve (normalized to plasma activity) to the kidney activity using the Rutland-Patlak space method; and 3) a regression equation measuring clearance from the percentage of the injected dose accumulating in the kidneys during the 1- to 2.5-minute period. The camera-assisted clearances were compared with the single-sample MAG3 clearances calculated using the Russell equation. Linear regression analysis was used to measure the correlation between the camera-based methods and the single-sample techniques. RESULTS: Correlation with r > 0.900 was found for all three techniques. The difference in correlation coefficients between the three methods was not significant; however, the regression line of method 3 was significantly closer to the line of identity (P = 0.005). CONCLUSION: Method 3 most closely fits the line of identity and is probably the most practical because no blood sample is needed.

Cerebral activation associated with sexual arousal in response to a pornographic clip: A 15O-H2O PET study in heterosexual men.

This study attempted to use PET and 15O-H2O to measure changes in regional cerebral blood flow (rCBF) during sexual arousal evoked in 10 young heterosexual males while they watched a pornographic video clip, featuring heterosexual intercourse. This condition was compared with other mental setups evoked by noisy, nature, and talkshow audiovisual clips. Immediately after each clip, the participants answered three questions pertaining to what extent they thought about sex, felt aroused, and sensed an erection. They scored their answers using a 1 to 10 scale. SPM was used for data analysis. Sexual arousal was mainly associated with activation of bilateral, predominantly right, inferoposterior extrastriate cortices, of the right inferolateral prefrontal cortex and of the midbrain. The significance of those findings is discussed in the light of current theories concerning selective attention, "mind reading" and mirroring, reinforcement of pleasurable stimuli, and penile erection.

Toward a catalog of human genes and proteins: sequencing and analysis of 500 novel complete protein coding human cDNAs.

With the complete human genomic sequence being unraveled, the focus will shift to gene identification and to the functional analysis of gene products. The generation of a set of cDNAs, both sequences and physical clones, which contains the complete and noninterrupted protein coding regions of all human genes will provide the indispensable tools for the systematic and comprehensive analysis of protein function to eventually understand the molecular basis of man. Here we report the sequencing and analysis of 500 novel human cDNAs containing the complete protein coding frame. Assignment to functional categories was possible for 52% (259) of the encoded proteins, the remaining fraction having no similarities with known proteins. By aligning the cDNA sequences with the sequences of the finished chromosomes 21 and 22 we identified a number of genes that either had been completely missed in the analysis of the genomic sequences or had been wrongly predicted. Three of these genes appear to be present in several copies. We conclude that full-length cDNA sequencing continues to be crucial also for the accurate identification of genes. The set of 500 novel cDNAs, and another 1000 full-coding cDNAs of known transcripts we have identified, adds up to cDNA representations covering 2%--5 % of all human genes. We thus substantially contribute to the generation of a gene catalog, consisting of both full-coding cDNA sequences and clones, which should be made freely available and will become an invaluable tool for detailed functional studies.

Gamma camera-mounted anatomical X-ray tomography: technology, system characteristics and first images.

Scintigraphic diagnosis, based on functional image interpretation, becomes more accurate and meaningful when supported by corresponding anatomical data. In order to produce anatomical images that are inherently registered with images of emission computerised tomography acquired with a gamma camera, an X-ray transmission system was mounted on the slip-ring gantry of a GEMS Millennium VG gamma camera. The X-ray imaging system is composed of an X-ray tube and a set of detectors located on opposite sides of the gantry rotor that moves around the patient along with the nuclear detectors. A cross-sectional anatomical transmission map is acquired as the system rotates around the patient in a manner similar to a third-generation computerised tomography (CT) system. Following transmission, single-photon emission tomography (SPET) or positron emission tomography (PET) coincidence detection images are acquired and the resultant emission images are thus inherently registered to the anatomical maps. Attenuation correction of the emission images is performed with the same anatomical maps to generate transmission maps. Phantom experiments of system performance and examples of first SPET and coincidence detection patient images are presented. Despite limitations of the system when compared with a state of the art CT scanner, the transmission anatomical maps allow for precise anatomical localisation and for attenuation correction of the emission images.

Intrinsic dual-energy processing of myocardial perfusion images.

UNLABELLED: We have developed a software-based method for processing dual-energy 201TI SPECT emission projection data with the goal of calculating a spatially dependent index of the local impact of gamma-ray attenuation. We refer to this method as intrinsic dual-energy processing (IDEP). METHODS: IDEP exploits the differential attenuation of lower energy emissions (69-83 keV) and higher energy emissions (167 keV) resulting from the decay of 201TI to characterize the relative degree of low-energy gamma-ray attenuation throughout the myocardium. In particular, IDEP can be used to estimate the relative probability that a low-energy gamma-ray emitted from a particular region of the myocardium is detected during the acquisition of SPECT projection data. Studies on phantoms and healthy human volunteers were performed to determine whether the IDEP method yielded detection probability images with systematic structure visible above the noise of these images and whether the systematic structure in the detection probability images could be rationalized physically. In patient studies, the relative regional detection probabilities were applied qualitatively to determine the likely effects of attenuation on the distribution of mapped photon emissions. RESULTS: Measurements of the detection probability in uniform phantoms showed excellent agreement with those obtained from computer simulations for both 180 degrees and 360 degrees acquisitions. Additional simulations with digital phantoms showed good correlation between IDEP-estimated detection probabilities and calculated detection probabilities. In patient studies, the IDEP-derived detection probability maps showed qualitative agreement with known nonuniform attenuation characteristics of the human thorax. When IDEP data were integrated with the findings on the emission scan, the correlation with coronary anatomy (known in 6 patients and hypothesized on the basis of clinical and electrocardiographic parameters in 5 patients) was improved compared with evaluating the mapped emission image alone. CONCLUSION: The IDEP method has the potential to characterize the attenuation properties of an object without use of a separate transmission scan. Coupled with the emission data, it may aid coronary diagnosis.

A new peptide-affinity tag for the detection and affinity purification of recombinant proteins with a monoclonal antibody.

A monoclonal anti-peptide antibody (2E11) was raised against the synthetic peptide 38 (C-L-D-K-S-G-L-P-S-D-R-F-F-A) representing a part of the variable region of the Vbeta 6.2 T-cell receptor. This mAb (IgG(1), kappa light chain) bound very specifically to peptide 38 as shown by ELISA but did not recognize the corresponding native Vbeta 6.2 T-cell receptor on T-cells. For epitope analysis, overlapping peptides of 4-10 amino acids in length corresponding to the sequence of peptide 38 were synthesized and assayed by SPOT synthesis on cellulose sheets. The shortest peptide recognized was L-P-S-D-R. The specificity of mAb 2E11 was examined with 100 different peptides comprising other parts of the different variable Vbeta domains of the human T-cell receptor that do not include the epitope region L-P-S-D-R. None of these peptides were recognized. The chemical synthesis of a peptide with the sequence L-P-S-D-R on Sepharose beads allowed to efficiently purify the mAb 2E11 in a single step by affinity chromatography. An equilibrium binding constant of 4.9x10(6) l/mol was determined for mAb 2E11 by using rhodamine-green-labelled peptide 38 in fluorescence correlation spectroscopy. In order to demonstrate that peptide 38 can be used as an affinity-tag, it was fused to the carboxyl-terminus of interferon regulatory factor-1 (IRF-1). It could be shown that in vitro translated peptide 38 tagged IRF-1 was immunoprecipitated by the mAb 2E11 and that the fusion protein could be purified by immunoaffinity chromatography. Additionally peptide 38 was fused to the amino-terminus of the Taq polymerase. This recombinant protein was expressed in E. coli and specifically detected in a Dot blot and Western blot using mAb 2E11.

mRNA stability and selenocysteine insertion sequence efficiency rank gastrointestinal glutathione peroxidase high in the hierarchy of selenoproteins.

The recently described gastrointestinal glutathione peroxidase (GI-GPx) is the fourth member of the family of the selenoenzymes glutathione peroxidases (GPx). In contrast to the more uniform distribution of, for example, the classical glutathione peroxidase (cGPx), it is expressed exclusively in the gastrointestinal tract and has, therefore, been suggested to function as a primary barrier against alimentary hydroperoxides. In order to get an idea of its relative importance we investigated its position in the hierarchy of selenoprotein expression. The selenium-dependent expression of GI-GPx was analyzed in comparison with that of other GPx types at the level of mRNA and protein in HepG2 and CaCo-2 cells. Furthermore, the selenocysteine insertion sequence (SECIS) efficiencies of GI-GPx, phospholipid hydroperoxide glutathione peroxidase (PHGPx) and cGPx in response to selenium were determined by a reporter-gene assay in human hepatoma cells and baby hamster kidney cells. GI-GPx mRNA levels increased during selenium deficiency, whereas cGPx mRNA levels decreased and PHGPx mRNA levels remained almost unaffected. In cells grown in selenium-poor media, all GPx-types were low in both activity and immunochemical reactivity. Upon selenium repletion immunoreactive GI-GPx protein reached a plateau after 10 h, whereas cGPx started to be expressed at 24 h and did not reach its maximum level before 3 days. SECIS efficiencies decreased in the order PHGPx > cGPx > GI-GPx. The augmentation of SECIS efficiencies by selenium was highest for cGPx and intermediate for PHGPx, whereas it was marginal for GI-GPx. The high mRNA stability under selenium restriction, the speed of biosynthesis upon selenium repletion and the marginal effect of selenium on the SECIS efficiency indicate that of the GPx isotypes, GI-GPx ranks highest in the hierarchy of selenoproteins and point to a vital role of GI-GPx in the gastrointestinal tract.

Preoperative thallium scanning, selective coronary revascularization, and long-term survival after carotid endarterectomy.

BACKGROUND AND PURPOSE: Long-term survival in patients after carotid endarterectomy (CEA) is determined mainly by their concomitant cardiac disease. We tested to determine whether preoperative thallium scanning (PTS) and subsequent selective coronary revascularization (CR), by either percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG), improve long-term survival after CEA. METHODS: Two hundred twenty-six of 255 consecutive patients (88%) undergoing CEA from 1990 to 1996 had PTS. Those with significant reversible defects on PTS were referred for coronary angiography and possible CR. Patients who had undergone PTS were divided into the following 4 groups: group 1, normal or mild defects on PTS; group 2, moderate-severe fixed and/or reversible defects in patients who did not undergo CR; group 3, patients who had CR secondary to their PTS results; and group 4, patients who had CR in the past that was not related to the PTS. Perioperative data were prospectively recorded, and data on long-term survival and cardiac and neurological complications were collected. RESULTS: Seventy-seven patients (34%) had preoperative coronary angiography, and 42 (19%) had subsequent CR: preoperative PTCA or CABG in 24, combined CEA+CABG in 10, and post-CEA CABG in 8 patients. No deaths resulted from the coronary angiography, CR, or CEA. Six patients had perioperative nonfatal myocardial infarction and 8 had stroke. During the follow-up (40+/-23 months), 47 patients (18%) died, 31 (66%) from cardiac disease and 4 (8.5%) from stroke. Independent predictors of long-term overall mortality were diabetes mellitus, preoperative T-wave inversion on ECG, lower-extremity arterial disease, and history of neurological symptoms [exp(beta)=3. 5, 3.4, 2.5, and 2.4; P=0.0003, 0.0004, 0.01, and 0.04, respectively]. In addition, preoperative moderate-severe thallium defect without CR (group 2) independently predicted long-term cardiac mortality [exp(beta)=2.8; P=0.04]. Patients with preoperative CR (group 3) had long-term survival rate similar to that of group 1 and significantly better than that of group 2 (P=0. 02). CONCLUSIONS: PTS predicts long-term survival, and selective CR based on the thallium results improves the survival rate of patients undergoing CEA.

Heart rate variability as a marker of myocardial perfusion.

RR variability (HRV), an independent predictor of death following myocardial infarction, may also be related to other features of coronary artery disease. We evaluated its ability to differentiate among sedentary patients with chest pain >/=45 years of age demonstrating either normal or abnormal myocardial perfusion with rest and exercise thallium-210 tomographic imaging. The major HRV difference between 48 men and 50 women with normal perfusion was a significantly higher high frequency power in women. No significant differences in mean HRV values were found between the 57 men with abnormal perfusion scans and the 48 men with normal perfusion. In both men and women with normal perfusion scans, duration of exercise was significantly related to age. In men with abnormal scans, impaired myocardial perfusion alters the relationship between exercise duration and age, and a group of individuals with diminished HRV and low levels of physical fitness, regardless of age, can be identified. Despite these latter selective findings, we conclude that HRV is not a sensitive indicator to differentiate patients with normal and abnormal myocardial perfusion.

Liver hemangioma. A perioperative Tc-99m RBC SPECT correlation.

Scintigraphic diagnosis of a liver hemangioma may be difficult when its size approaches the spatial resolution of a gamma camera, and it may not be visualized on a Tc-99m tin-colloid liver SPECT study. The contribution of Tc-99m labeled RBC scintigraphy is shown in a patient with a liver hemangioma discovered during laparoscopic cholecystectomy for chronic cholecystitis. Despite negative CT, US, and Tc-99m tin-colloid SPECT of the liver, Tc-99m labeled RBC SPECT disclosed a focus of increased activity consistent with the hemangioma.

Synthesis of mono- and bifunctional peptide-dextran conjugates for the immobilization of peptide antigens on ELISA plates: properties and application.

Dextran has been used as a carrier molecule for the synthesis of monofunctional peptide-dextran conjugates. The immunodetection of such carrier immobilized peptides on ELISA plates was compared to that of peptides adsorbed directly to immunoplates. The main features observed with peptide-dextran conjugates were as follows: only small amounts of peptide (1-2 mg) were necessary for coupling via alpha- or epsilon-amino groups to NaIO4-activated dextran (4 mg); the coupling yield was up to 68%; an amino acid analysis of the conjugate enabled the amount of carrier immobilized peptide to be calculated; an estimated 15-17 peptides were bound per dextran molecule (MW 73,500); using a carbohydrate as carrier reduces the possibility of non-specific interactions because no hydrophobic or ionic sites and no protein-like epitopes exist on the carrier apart from the peptide ligand. It can be assumed that some peptide ligands provide the forces for an interaction with the plate surface whereas other remain free for the interaction with the antibody. Thus, the detection with monoclonal anti-peptide antibodies allowed peptide-dextran conjugates to be used at coating concentrations of 1-3 nM peptide, corresponding to 0.6-2.6 ng peptide-dextran per well. In contrast, concentrations of 150-500 nM were required for coating with peptides. The applicability of monofunctional peptide-dextran conjugates was demonstrated by investigating the titer and specificity of a polyclonal anti-peptide serum developed against human gastrointestinal glutathione peroxidase. The introduction of biotin as a second ligand of the dextran conjugate permitted its capture on streptavidin coated plates. This synthesis of bifunctional peptide-biotin-dextran conjugates opens up additional possibilities for applications.

Increased cerebral blood flow in depressed patients responding to electroconvulsive therapy.

UNLABELLED: Considerable data support the existence of impaired regional cerebral blood flow (rCBF) in major depression. We compare rCBF in depressed patients before and after electroconvulsive therapy (ECT) to define whether the impairment is a "state"-related property or a trait phenomenon. METHODS: Twenty patients with a major depressive disorder were studied by 99mTc-HMPAO brain SPECT, 2-4 days before and 5-8 days after a course of ECT. Three transaxial brain slices delineating anatomically defined regions of interest at approximately 4, 6 and 7 cm above the orbitomeatal line were used, with the average number of counts for each region of interest normalized to the area of maximal cerebellar uptake. RESULTS: Technetium-99m-HMPAO uptake significantly increased in patients who responded to ECT but remained unchanged in patients who did not respond to the treatment (response defined as a reduction of at least 60% on the Hamilton Depression Rating Scale). An inverse correlation was observed between severity of depression and HMPAO uptake, and clinical improvement was positively correlated with the increase in tracer uptake. CONCLUSIONS: These findings imply that reduced rCBF in depression, as reflected in brain 99mTc-HMPAO uptake, is a "state"-related property and is reversible by successful treatment. Technetium-99m-HMPAO uptake may serve as an objective state marker for depression, an an indicator of the severity of depression and as an objective means of evaluating response to treatment.

Human monoclonal antibodies to cytomegalovirus. Characterization and recombinant expression of a glycoprotein-B-specific antibody.

Human monoclonal antibodies (mAb) to human cytomegalovirus (HCMV) were established from spleen cells of a HCMV-positive donor. The antibodies (gamma 3, lambda) secreted from a stable heterohybridoma cell line were further characterized by immunoprecipitation and immune-fluorescence microscopy using HCMV infected cells and recombinant cell lines expressing HCMV glycoprotein B. The antibody reacted with the entire glycoprotein B or the extracellular domain expressed as glycoprotein-B--beta-galactosidase fusion protein in the native state, but the antibody was not neutralizing HCMV. Denatured and reduced forms of glycoprotein B were not recognized by this antibody, however, native glycoprotein B on the surface of infected cells was detected efficiently. The genes encoding the Fab part of the antibody were cloned and expressed in Escherichia coli. Recombinant Fab fragments specifically binding the extracellular domain of glycoprotein B could easily be isolated from the periplasmic space. Recombinant antibodies provide the opportunity to modify effector functions and to add tags to diagnostic antibodies for more efficient detection of CMV-infected cells.

Value of dobutamine/nitrate radionuclide angiography in predicting revascularization effects on ventricular function.

OBJECTIVE: Dobutamine and Nitrate Radionuclide Angiography (RNA) may help to distinguish viable from nonviable myocardium and to predict revascularization effects on LV function. SETTING: Ambulatory. EXPERIMENTAL DESIGN: Prospective. PATIENTS AND METHODS: We studied 12 patients (11 male, 1 female; mean age 56 +/- 10 years) with three-vessel disease, severe LV dysfunction, and prior MI for a mean follow-up time of 10 +/- 3.4 months. Thallium-201 scintigraphy favored potential viability in all patients: inducible ischemia with satisfactory perfusion in more than one coronary arterial territory. Global and regional LVEF's were calculated from preoperative RNA (baseline rest study and with continuous dobutamine infusion with gradual rate increase plus oral nitrates) and postoperative RNA at 1 and 6 months. RESULTS: There was no operative mortality, but two late deaths occurred. Symptomatically, most patients showed improvement. Global LVEF increased during dobutamine and nitrates preoperatively (p < 0.01), but not at 1 and 6 months postoperatively (without pharmacological intervention). Mean LVED volume was not significantly changed postoperatively. Regional EF improvement was found in 4 out of 9 LV wall segments under dobutamine and nitrates, and this increase persisted postoperatively at 1 and 6 months. CONCLUSIONS: Mild but significant increase in global LVEF during dobutamine and nitrates administration is not predictive of postoperative LVEF improvement. However, regional EF improvement appears to be predictive of post-revascularization LV functional improvement.

Transient neurological events during dipyridamole stress test: an arterial steal phenomenon?

Dipyridamole-associated adverse neurological side effects have not been extensively described. We present two cases of dipyridamole-associated transient motor neurological events with no evidence of residual neurological deficits detected clinically or by head CT. The patients showed no evidence of significant extracranial (internal carotid) artery disease. We propose the presence of a regional cerebral perfusion disturbance due to an intracranial vascular steal phenomenon as the mechanism for the above side effects of dipyridamole.

A measurement of pulmonary blood volume increase during systole in humans.

Pulmonary blood volume increase during systole was measured in patients by analysing chest images obtained during ECG gated radionuclide angiography examination. The difference in the total radiation counts between systole and diastole in regions of interest, which included the lungs and the left ventricle, was measured and the relative pulmonary systolic blood volume increase (SBVI)-the ratio between the pulmonary SBVI and the cardiac stroke volume-was calculated. The relative pulmonary SBVI, which is a measure for the compliance of the pulmonary blood vessels, was found to be 0.26-0.85, and the average value was 0.57 +/- 0.15. The relative pulmonary SBVI was inversely correlated with the patient age (r = 0.27, p < 0.05) and with the left ventricular ejection fraction and stroke volume (r = 0.36, p < 0.01) due to decreased arterial compliance for older patients and for increased pulmonary blood volume respectively. The correlation coefficients were not high, indicating that the compliance of the patients is determined mainly by other individual factors. Radionuclide plethysmography enables qualitative assessment of pulmonary arterial compliance.

The use of iridium-191m for pulmonary blood flow imaging.

A preliminary evaluation of the potential utilization of osmium-191/iridium-191m for pulmonary blood flow imaging was performed. This evaluation was part of a more general study concerning the use of 191mIr for first-pass radionuclide angiocardiography (FPRNA). In eight selected patients with suspected pulmonary disease, we generated, from the data collected during FPRNA, an image representing blood flow distribution to the lungs. A software program was developed in order to differentiate the lungs from the heart, to define the wash-in lung phase and finally to construct an image representing pulmonary blood flow distribution. We compared that image with a standard lung perfusion image using technetium-99m macroaggregated albumin (MAA) and plain chest X-ray and computerized tomography (CT). The obtained 191mIr perfusion images showed a spatial activity distribution similar to that seen on 99mTc-MAA lung perfusion scans, and in most cases the same perfusion defects. Disease revealed by plain chest X-ray and CT was nicely correlated with perfusion defects seen on the 191mIr images. The combined information of lung perfusion and dynamic cardiac parameters obtained by FPRNA (right and left ventricular ejection fractions) added another relevant dimension to the clinical picture of patients with pulmonary embolism, chronic obstructive lung disease, lung tumour or suspected congestive heart failure. We conclude that 191mIr may become a practical tool for achieving the conceptually promising approach of combined lung-heart real-time imaging.