Oral Vaccination with Hepatitis E Virus Capsid Protein and Immunobiotic Bacterium-Like Particles Induce Intestinal and Systemic Immunity in Mice

The hepatitis E virus (HEV) genotype 3 (GT3) is an emergent pathogen in industrialized countries. It is transmitted zoonotically and may lead to chronic hepatitis in immunocompromised individuals. We evaluated if the major antigen of HEV, the capsid protein, can be used in combination with immunobiotic bacterium-like particles (IBLP) for oral vaccination in a mouse model. We have cloned and expressed the RGS-His₅-tagged HEV GT3 capsid protein (ORF2) in E. coli and purified it by NiNTA. IBLP were obtained from two immunobiotic Lactobacillus rhamnosus strains acid- and heat-treated. ORF2 and the IBLP were orally administered to Balb/c mice. After three oral immunizations (14-day intervals), blood, intestinal fluid, Peyer´s patches, and spleen samples were drawn. IgA- and IgG-specific antibodies were determined by ELISA. Mononuclear cell populations from Peyer's patches and spleen were analyzed by flow cytometry, and the cytokine profiles were determined by ELISA to study cellular immunity. Orally administered recombinant ORF2 and IBLP from two L. rhamnosus strains (CRL1505 and IBL027) induced both antigen-specific humoral and cellular immune responses in mice. IBLP027 was more effective in inducing specific secretory IgA in the gut. IFN-γ, TNF-α, and IL-4 were produced by Peyer's plaques lymphocytes stimulated with ORF2 ex vivo suggesting a mixed Th1/Th2-type adaptive immune response in immunized mice. Oral vaccines are not invasive, do not need to be administered by specialized personal, and elicit both systemic and local immune responses at the port of entry. Here, we present an experimental oral vaccine for HEV GT3, which could be further developed for human and/or veterinary use.

Are there intracellular Ca2+ oscillations correlated with flagellar beating in human sperm? A three vs. two-dimensional analysis

STUDY QUESTION

Are there intracellular Ca2+ ([Ca2+]i) oscillations correlated with flagellar beating in human sperm?

SUMMARY ANSWER

The results reveal statistically significant [Ca2+]i oscillations that are correlated with the human sperm flagellar beating frequency, when measured in three-dimensions (3D).

WHAT IS KNOWN ALREADY

Fast [Ca2+]i oscillations that are correlated to the beating flagellar frequency of cells swimming in a restricted volume have been detected in hamster sperm. To date, such findings have not been confirmed in any other mammalian sperm species. An important question that has remained regarding these observations is whether the fast [Ca2+]i oscillations are real or might they be due to remaining defocusing effects of the Z component arising from the 3D beating of the flagella.

STUDY DESIGN, SIZE, DURATION

Healthy donors whose semen samples fulfill the WHO criteria between the age of 18-28 were selected. Cells from at least six different donors were utilized for analysis. Approximately the same number of experimental and control cells were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Motile cells were obtained by the swim-up technique and were loaded with Fluo-4 (Ca2+ sensitive dye) or with Calcein (Ca2+ insensitive dye). Ni2+ was used as a non-specific plasma membrane Ca2+ channel blocker. Fluorescence data and flagella position were acquired in 3D. Each cell was recorded for up to 5.6 s within a depth of 16 microns with a high speed camera (coupled to an image intensifier) acquiring at a rate of 3000 frames per second, while an oscillating objective vibrated at 90 Hz via a piezoelectric device. From these samples, eight experimental and nine control sperm cells were analyzed in both 2D and 3D.

MAIN RESULTS AND THE ROLE OF CHANCE

We have implemented a new system that allows [Ca2+]i measurements of the human sperm flagellum beating in 3D. These measurements reveal statistically significant [Ca2+]i oscillations that correlate with the flagellar beating frequency. These oscillations may arise from intracellular sources and/or Ca2+ transporters, as they were insensitive to external Ni2+, a non-specific plasma membrane Ca2+ channel blocker.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

Analysis in 3D needs a very fast image acquisition rate to correctly sample a volume containing swimming sperm. This condition requires a very short exposure time per image making it necessary to use an image intensifier which also increases noise. The lengthy analysis time required to obtain reliable results limited the number of cells that could be analyzed.

WIDER IMPLICATIONS OF THE FINDINGS

The possibility of recording flagellar [Ca2+]i oscillations described here may open a new avenue to better understand ciliary and flagellar beating that are fundamental for mucociliary clearance, oocyte transport, fertilization, cerebrospinal fluid pressure regulation and developmental left-right symmetry breaking in the embryonic node.

STUDY FUNDING AND COMPETING INTEREST(S)

This work was supported by Consejo Nacional de Ciencia y Tecnología (CONACyT) (grants 253952 to G.C.; 156667 to F.M.M. and Fronteras 71 39908-Q to A.D. and Post-doctoral scholarships 366844 to P.H.-H. and 291028 to F.M.) and the Dirección General de Asuntos del Personal Académico of the Universidad Nacional Autónoma de México (DGAPA-UNAM) (grants CJIC/CTIC/4898/2016 to F.M. and IN205516 to A.D.). There are no conflicts of interest to declare.

[Patient with a Fontan circulation undergoing caesarean section: Anesthesiological management]

Adults suffering from congenital heart diseases (CHD) represent a challenge to anesthesiologists because of the diverse pathologies, complex pathophysiology and special treatment strategies. Due to improved therapeutic options for CHD, patient quality of life and life expectancy is increasing, leaving them as a growing population including pregnant patients with CHD. This article presents the main principles of the pathophysiology and anesthesiological management of pregnant patients living with a Fontan circulation based on a case report, which was complicated by an aortic coarctation and atonic uterine hemorrhage.

[Long-term visual outcome comparison of bilateral implantation of apodised diffractive versus progressive multizonal refractive multifocal intraocular lenses after cataract extraction]

AIM

The aim of this study was to evaluate the functional effect of bilateral implantation of apodised diffractive versus progressive multizonal refractive multifocal intraocular lenses compared to standard monofocal intraocular lenses.

PATIENTS AND METHOD

229 patients underwent cataract extraction; 66 Array SA40N (AMO, Irvine, CA, USA), 76 SA60D3 ReSTOR (Alcon, Fort Worth, TX, USA), and 87 MA60AC (Alcon, Fort Worth, TX, USA) were implanted. In this retrospective trial the main outcome measures were near, intermediate, and distance visual acuity and assessment of subjective function by questionnaire.

RESULTS

Mean follow-up was 4.7 ± 1.4 years with monofocal, 6.6 ± 1.7 with Array and 4.3 ± 1.1 with ReSTOR implants. Uncorrected binocular distance visual acuity was equivalent in the three groups. Uncorrected binocular near and intermediate visual acuity and spectacle independence were significantly higher in the two multifocal groups (p < 0.001). Glare and halos were more bothersome with multifocal than monofocals implants (p < 0.05) and adverse visual symptoms at night with Array implants but equivalent between ReSTOR patients and monofocal patients. Between the two multifocal groups spectacle independence was higher and adverse visual symptoms lower in ReSTOR patients than in Array patients (p < 0.05). ReSTOR patients reported a higher overall visual satisfaction than the other groups (p < 0.001) and rated their vision at 8.8 ± 1.8. Monofocal patients reported a slightly higher satisfaction at 7.6 ± 1.7 compared to Array patients at 6.9 ± 2.6 (p = 0.05).

CONCLUSION

In this long-term study the highest overall visual satisfaction could be achieved by bilateral implantation of apodised diffractive intraocular lenses.

[Neurodevelopment of extremely low birthweight infants born in Erasmus Hospital between 1992 and 2001]

Survival of extremely low birth weight infants has dramatically improved in the last decade of the twentieth century. The objective of our study was to evaluate the neurological evolution of the surviving infants because frequent motor, sensitive and psychological disturbances are related. Prospective, longitudinal study in a population of newborns, nursed in our neonatal intensive care unit and born between 1992 and 2001 with less than 1.000 g and/or less than 28 weeks of gestational age (GA). Neurological assessment of outcome was made using the neurodevelopmental score (O.M.S. 1988) at 6, 9, 12, 18, 24 and 36 months. Neurological follow-up every year and neuropsychological testing at 3, 5 and 8 years. Only children with at least 2 years of follow-up were included. The children were grouped in 3 categories: M (major neurological handicap), m (minor neurological handicap), N (normal neurological outcome). To evaluate the evolution with time, we compared the results from the first period (1992 to 1996) to the second part of this decade (1997 to 2001). Mortality fell from 38% (27/70) in the first period (1992-1996) to 18% (8/44) in the second one (1997-2001) (p = 0.02) including neonates of less than 25 weeks GA. Neurodevelopmental status improved and severe brain lesions decreased (25% with intraventricular haemorrhage III & IV and cystic periventricular leukomalacia versus 6% in the second period) (p = 0.017). Major handicap fell from 26% (9/34) to 16% (5/31) and normal neurological evolution raised from 15% (5/34) to 48% (15/31) (p = 0.013). With the survival of newborns less than 28 weeks, the severe ocular complications increased: 6% (5/79). In conclusion, mortality and quality of life have significantly improved in the past 10 years in our service. Severe brain lesions have decreased under a better multifactorial management. Nevertheless when the gestational age of the surviving babies diminishes, ocular sequelae increase. We still think that prematurity remains a burden for the child, his family and the society.

[Papillary hemodynamics in patients with normal pressure glaucoma and hemorrhage of the optic papilla circumference]

BACKGROUND

Optic disc hemorrhages in patients with normal-pressure glaucoma (NPG) are usually regarded as a sign of vascular dysfunction and as an indicator for glaucoma damage progression.

METHODS

Optic nerve head blood flow was measured in 21 patients suffering from NPG with acute optic disc hemorrhages by scanning laser Doppler flowmetry at various locations of the optic disc. Intraocular pressure and mean deviation of the visual field were also monitored. Two groups served as control: 21 patients with NPG matched for age, sex, and stage of the disease and in addition the contralateral eye without any hemorrhages.

RESULTS

Optic nerve head blood flow as a mean of several locations was significantly lower in eyes with optic disc hemorrhages than in controls and differed significantly from the contralateral eye.

CONCLUSION

Optic nerve blood flow was lower in NPG eyes with optic disc hemorrhages than in the contralateral eye and in controls.

Mural aortic thrombi: An important cause of peripheral embolization

PURPOSE

Arterial thromboembolism in patients with an unknown source of embolization is still associated with significant morbidity and mortality. The advent of transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) and the more frequent use of computed tomography (CT) have led to the identification of mural aortic thrombi (MAT) as a source of distal embolization in a much higher proportion of patients than previously appreciated. The incidence, diagnosis, and treatment of patients with MAT is reported.

METHODS

In a prospective study, from January 1996 to December 1998, 89 patients with acute embolic events underwent an extensive diagnostic workup, consisting of TEE, CT, or MRI, to detect the source of embolization. Patients in whom the heart (n = 51), occlusive aortoiliac disease (n = 16), or aortic aneurysms (n = 12) was identified as the source of embolization were excluded.

RESULTS

Five female and three male patients, with a median age of 63 years (range, 35 to 76 years), with bilateral or repetitive embolic events resulting from MAT were identified, representing 9% of all patients with arterial thrombembolism. All patients had several risk factors for atherosclerosis, but only one young patient had a single risk factor that promoted thrombosis. Successful percutaneous catheter aspiration embolectomy was performed in six patients. The remaining two patients underwent surgical thromboembolectomy. A below-knee amputation had to be performed in two patients, thus representing a morbidity of the primary treatment of 25%. MAT of equal value were detected in the ascending (n = 1) and thoracic aorta (n = 3) by means of TEE, CT, or MRI. MAT in the abdominal aorta (n = 4) were identified by means of CT and MRI. Surgical removal of MAT was performed in seven patients by means of graft replacement of the ascending aorta (n = 1), open thrombectomy of the descending aorta (n = 2), and thrombendarterectomy of the abdominal aorta (n = 4), without intraoperative or postoperative complications. No recurrence of MAT occurred during a median follow-up period of 13 months (range, 4 to 24 months).

CONCLUSION

MAT represent an important source of arterial thrombembolism. A diagnostic workup of the aorta, preferably by means of CT or MRI, should be performed in all patients in whom other sources of embolization have been ruled out. The ideal therapeutic approach to these patients still awaits prospective evaluation. However, based on our experience, MAT can be successfully treated with a definitive surgical procedure in selected patients, with low mortality and morbidity.

Evaluation of coronary bypass flow with color-Doppler and magnetic resonance imaging techniques: comparison with intraoperative flow measurements

OBJECTIVES

After coronary artery bypass surgery, patency and flow assessment is based on invasive methods such as angiography and intravascular ultrasound or flow wire techniques. The aim of the study was to compare intraoperative transit time flow measurements of coronary bypass grafts with early postoperative color-Doppler and MR-imaging assessment.

METHODS

In 22 patients (62+/-8.5 years) undergoing elective coronary bypass surgery the flow was measured in all internal mammary artery grafts (IMA) and saphenous vein grafts using the transit time flow technique. Postoperatively (days 5-7) all patients had a color-Doppler IMA graft assessment followed by a MR-angiography and flow measurement (navigator echo phase contrast technique with and without contrast bolus application) to determine patency and graft flow.

RESULTS

Data are expressed as the mean +/- SD). (1) In all patients the left IMA graft to the left anterior descending coronary artery (LAD) could be identified and flow could be assessed with both color-Doppler and MRI. Venous grafts could only be visualized by MRI. The use of an intravenous contrast bolus enhanced the visualization of coronary artery bypass grafts. (2) The mean IMA to LAD flow was 33+/-17 ml/min intraoperatively by transit time and postoperatively 36+/-25 ml/min by MR respectively 66+/-54 ml/min by color-Doppler technique. (3) The systolic/diastolic flow ratio was 0.44+/-0.12 intraoperatively and 0.43+/-0.17 postoperatively by MR respectively 0.67+/-1.0 by color-Doppler. (4) A statistically significant correlation could be demonstrated between intraoperative transit time and postoperative MR flow measurements (r = 0.57; P < 0.04), whereas the correlations to color-Doppler flow were poor. Postoperatively MR and color-Doppler showed a good correlation of systolic/diastolic flow ratio (r = 0.88; P < 0.008).

CONCLUSIONS

The color-Doppler method during echocardiography and MR-imaging are useful non-invasive techniques to visualize postoperative IMA grafts for patency assessment. The quantification of IMA flow is still difficult with either technique, but MR flow measurements showed the best correlation to the intraoperatively measured transit time flow. The MR technique is the most promising non-invasive method for postoperative evaluation of coronary bypass grafts, since it allows visualization and reliable flow quantification.

Assessment of cardiac rejection by MR-imaging and MR-spectroscopy

BACKGROUND

Detection of cardiac rejection is a major problem in cardiac transplantation. The gold standard is, and remains, endomyocardial biopsy.

PURPOSE

Evaluation of MR-imaging and MR-spectroscopy for detection of cardiac rejection.

METHODS

Orthotopic cardiac transplantation (HTX) was performed in 13 pigs (body weight 30 kg). All animals obtained immunosuppressive (triple) therapy for 1 week after the operation. Thereafter immunosuppression was stopped to induce cardiac rejection. MRI and MRS (1.5 Tesla General Electrics Signa) were performed pre- and post-operatively on days 10, 17, 24 and 31. The degree of rejection was determined post-operatively using endomyocardial biopsy (Texas grading score).

RESULTS

(1) MR-imaging: LV function remained unchanged after HTX. LV mass increased (+42%; P < 0.05) with cardiac rejection. (2) MR-spectroscopy: a marked reduction in the ratio of phosphocreatine and adenosine triphosphate, respectively, to inorganic phosphate was observed in the rejecting hearts. (3) Histologic grading confirmed cardiac rejection after stopping immunosuppression. The Texas score was 5.7+/-0.8 at autopsy.

CONCLUSIONS

MR-imaging and MR-spectroscopy allow the detection of changes associated with cardiac rejection. Both techniques are correlated with histologic rejection. However, endomyocardial biopsy remains the gold standard for reliable detection of cardiac rejection.

[The significance of magnetic resonance venography in the pre-interventional clarification of a malignant superior venous obstruction]

PURPOSE

Comparison between peripheral digital subtraction venography (DSV) and magnetic resonance venography (MRV) in planning for stent placement in malignant superior central venous obstruction.

METHOD

19 patients with malignant central vein obstruction were examined by DSV (n = 19) and MRV (n = 19). For each patient 12 segment-vessel evaluation was performed to review for obstruction and then compared with the gold standard--selective catheter phlebography--performed at the time of stent insertion. Additionally, tumor extension and collateral venous outflow was noted.

RESULTS

Sensitivity, specificity, and accuracy amounted to 92%, 96%, and 95% for DSV and 98%, 100%, and 100%, respectively for MRV. The McNemar test revealed a significance between MR venography and DSV.

CONCLUSIONS

With regard to planning of stent placement, a more exact evaluation was possible with MR venography than with DSV. Thus, MR venography can replace DSV as the method of choice for clarifying malignant superior central vein obstructions prior to stent placement.

Can the IVIM model be used for renal perfusion imaging?

OBJECTIVE

Renal perfusion imaging may provide information about the hemodynamic significance of a renal artery stenosis and could improve noninvasive characterization when combined with angiography. It was proposed previously that diffusion sequences could provide useful perfusion indices based on the intravoxel incoherent motion (IVIM) model. Owing to motion artifacts, diffusion imaging has been restricted to relatively immobile organs like the brain. With the availability of single-shot echo-planar imaging (EPI) our purpose was to evaluate the IVIM model in renal perfusion.

METHODS AND MATERIAL

Eight volunteers underwent diffusion-sensitive magnetic resonance (MR) imaging of the kidneys using a spin echo (SE) EPI sequence. The diffusion coefficients determined by a linear regression analysis and fits to the IVIM function were calculated.

RESULTS AND CONCLUSION

Our preliminary experience does not support the possibility of obtaining perfusion information using the IVIM model in the kidneys.

[The focus in neonatology]

During the last years, neonatology has greatly improved. In the last decade, mortality and morbidity have decreased: mortality from respiratory failure of prematurity has decreased from 22% to 12%, mortality of the very low birthweight infants under 1000 g fell from 56% to 35% and mortalities related to asphyxia have diminished from 21% to 12% and to malformations from 33% to 28%. Prematurity is now the first cause of neonatal mortality. During this period, the number of babies under 1000 g has increased 4-fold and the number of multiple births increased more than 2-fold from 3% to 7% of the live births of our hospital. Attitudes towards the premature infant have changed, especially towards the extremely small (called the micropremies). The number of disabled children has increased in parallel with the better survival of the very immature newborns who till recently were not resuscitated.

The influence of reperitonization on the induction of formation of intraperitoneal adhesions by a polypropylene mesh prosthesis. An experimental study in rats

The correction of groin hernias has increasingly been performed by transperitoneal videolaparoscopic methods, using a polypropylene mesh. This could lead to an increased incidence of adhesion formation. The incidence of adhesions induced by mesh placement and the influence of reperitonization was observed on 40 male adult Wistar rats. Adhesions were significantly more common on the groups in which the prosthesis was placed (59% vs 95%; p = 0.01), as well as on the groups in which reperitonization was performed (58% vs 100%; p = 0.03). The results suggest that polypropylene mesh placement and reperitonization are each independent factors in the induction of adhesions formation.

Proximal coronary artery stenosis: three-dimensional MRI with fat saturation and navigator echo

The purpose of this study was to compare the diagnostic value of MR angiography (MRA) with conventional contrast angiography in coronary artery disease. Thirty-five patients underwent MRA and coronary angiography within 4 hours. Of these, three patients were investigated twice: once before and once after balloon angioplasty. The pulse sequence was a cardiac-triggered, single-slab, three-dimensional gradient-echo sequence, employing a spin-echo navigator echo measurement to track the variation of the diaphragm during the scan. The following segments of the coronary arteries were included in this prospective study: left main coronary artery, proximal and middle left anterior descending, proximal and middle left circumflex, proximal and middle right coronary artery, and intermediate branch, if present. In total, 176 segments were classified as normal or having a stenosis of less than 50% and as having a stenosis of more than 50%. Five patients were excluded because of lack of cooperation. Over all, 45 of 54 stenoses were detected and interpretable by MRA. Sensitivity, specificity, and positive and negative predictive values of MRA for detecting significant stenoses were 83%, 94%, 87%, and 93%, respectively. MRA identified significant stenoses within the major coronary arteries with a high degree of accuracy. Sensitivity and specificity are higher compared with exercise tests or scintigraphy or top of the precise localization.

Cardiac metastasis of an esthesioneuroblastoma

Images

Case report: lymphoepithelial cyst of the pancreas

The case of a rare lymphoepithelial cyst of the pancreas is presented. The non-specific findings on endoscopic retrograde cholangiopancreaticography, endoscopic ultrasound, computed tomography and magnetic resonance imaging are discussed.

[Magnetic resonance angiography of the carotid artery: effect of short and ultra-short echo times]

PURPOSE

To evaluate the influence of short and ultrashort echo times (TE) on the magnetic resonance (MR) signal in the carotid sinus and in carotid artery stenoses.

MATERIAL AND METHODS

High resolution gradient-echo sequences without and with flow compensation using TE's ranging from 1.5 to 8.0 ms were compared on phantoms, eight healthy volunteers, and 10 patients with moderate and severe carotid artery stenoses.

RESULTS

MR sequences with shortest TE's provided the best visualisation of stenotic regions in the carotid sinus and demonstrated a substantial reduction of signal loss due to spin dephasing in both phantom and patient studies. This was made possible using an improved gradient system with higher gradient strengths and shorter rise times with lower acquisition bandwidths and better signal-to-noise ratio.

CONCLUSION

MR sequences with short and ultrashort TE's enable a better definition of the stenotic region and therefore guide adequate therapeutic decisions.

Spontaneous dissection of the hepatic artery

Two cases of spontaneous dissection of hepatic arteries are described. Presentation and management of these two patients are distinctly different. The first patient presented with mild back pain and mild abnormal liver function tests and was treated conservatively. The second patient presented with hemoperitoneum and shock and was treated surgically.

Magnetic resonance angiography of the abdomen

The applications of abdominal MR angiography have been slow as compared with its applications in the head and neck mainly because of greater technical difficulties in dealing with respiratory motion and the use of the body coil, which has a poorer signal-to-noise ratio than head or surface coils. Further work is needed to reduce motion sensitivity and improve spatial resolution. Flow contrast and depiction of slowly flowing blood could be improved with the use of intravascular contrast agents. 52MR angiography is the imaging method of choice in the evaluation of the portal venous system, systemic veins, and aortic disease. With further technical improvements, it seems likely that applications of MR angiography will also be extended to smaller vessels.

Functional imaging of the kidney by means of measurement of the apparent diffusion coefficient

PURPOSE

To determine the relationship between the apparent diffusion coefficient (ADC) and renal function.

MATERIALS AND METHODS

Twenty-three volunteers and seven pigs underwent diffusion-sensitive magnetic resonance (MR) imaging of the kidneys with a stimulated-echo acquisition mode excitation and echo-planar imaging readout under various physiologic conditions. The effect of hydration and anisotropic diffusion was studied in human subjects, and the effect of renal artery stenosis, ureteral obstruction, and diuresis was studied in the animal model.

RESULTS

The renal ADC values of dehydrated subjects were substantially increased with rehydration. Diffusion was highest in the medulla, with a pronounced radial component in the renal collecting system. In the pig model, induced renal artery stenosis resulted in immediate decrease in renal ADC; the degree of change was related to the flow deficit. The ADC also decreased with ureteral obstruction, but diuresis had no meaningful effect.

CONCLUSION

In vivo measurement of ADC has the potential for use as a noninvasive means to explore the functional status of the kidney.

Fast MR imaging of the liver: quantitative comparison of techniques

PURPOSE

To compare several techniques for fast magnetic resonance (MR) imaging of focal liver lesions.

MATERIALS AND METHODS

Ninety patients (37 men and 53 women, aged 19-92 years [mean, 54 years]) with 137 focal liver lesions (56 metastases, 13 hepatocellular carcinomas, 52 hemangiomas, 16 cysts) underwent MR imaging with rapid acquisition spin-echo (RASE), T1-weighted fast low-angle shot (FLASH), turboFLASH, segmented turboFLASH, and T2-weighted conventional and turbo spin echo (SE). Images were analyzed for spleen-to-liver and lesion-to-liver signal difference-to-noise ratios (SD/Ns).

RESULTS

Turbo SE T2-weighted imaging had the highest SD/N for spleen-to-liver (P < .01) and for lesion-to-liver (P < .02) contrast. Segmented T1-weighted turboFLASH imaging had the second highest SD/N for spleen-to-liver (P < .001) contrast and was better overall than other T1-weighted sequences for depicting liver lesions (P < .01). Results at segmented turboFLASH imaging were second best for hemangiomas (P < .01). For metastases, no significant difference was found for results with the T1-weighted sequences.

CONCLUSION

Segmented T1-weighted turboFLASH and turbo SE T2-weighted imaging hae advantages over conventional techniques for liver imaging.

[The in-vivo diffusion measurements of the liver, kidneys, spleen and m. erector with an echo-planar imaging system in normal subjects]

A diffusion sensitive pulse sequence using a stimulated echo (STEAM) type excitation and echo-planar (EPI) readout was developed on a 1.5 T echo-planar MR imaging system. Using this sequence the authors measured the apparent diffusion coefficients (ADC) of water in normal human liver, spleen, muscle and kidney in 12 volunteers. ADCs measured in normal volunteers were: liver, 1.39 +/- 0.16 x 10(-3) mm2/s, spleen, 0.95 +/- 0.15 x 10(-3) mm2/s, muscle, 1.99 +/- 0.16 x 10(-3) mm2/s, kidney, 3.54 +/- 0.47 x 10(-3) mm2/s. A large scatter of the ADCs in the kidneys was found in the different degrees of hydration status among the volunteers and also due to inter-subject variability. With further clinical experience, in vivo diffusion measurements of the abdominal organs may prove helpful in the identification and classification of abdominal disease by MRI.

[The role of magnetic resonance angiography prior to the transjugular placement of a portosystemic stent shunt (TIPS)]

The authors employed magnetic resonance angiography (MRA) to guide catheter placement for transjugular intrahepatic portosystemic stent shunt (TIPS) procedures in 14 of 24 patients, and compared the results to the 10 patients who did not have prior planning based on MRA. Two-dimensional time-of-flight venography was performed during breath holding, and projection venograms were formatted in sagittal, coronal and axial planes. MRA defined venous anatomy sufficiently well to shorten the procedure and helped to minimize invasiveness. With MRA guidance, intrahepatic needle punctures were significantly fewer (without MRA guidance: mean 12.1; with MRA guidance: mean 3.5, p < 0.001) and associated complications were absent (without MRA guidance: failed placement, N = 1; bleeding requiring blood transfusions, N = 2; death complicating intraperitoneal haemorrhage with haemobilia, N = 1, and hepatic capsular perforation, N = 1). The average time for the procedure was 2.8 hours without MRA guidance and 1.8 hours with MRA guidance (p < 0.0005). The authors conclude that MR angiography is a useful technique to define portal and hepatic venous anatomy prior to TIPS, and planning based on MRA may decrease the difficulty and length of the procedure.

Pancreatic tumors: evaluation with endoscopic US, CT, and MR imaging

PURPOSE

To compare the value of endosonography (endoscopic ultrasound [US]), dynamic computed tomography (CT), and magnetic resonance (MR) imaging in the evaluation of pancreatic tumors.

MATERIALS AND METHODS

Forty-nine consecutive patients with clinical suspicion of pancreatic tumor underwent endoscopic US (n = 49), CT (n = 46), and MR imaging (n = 25). The final diagnosis of a malignant (n = 22), benign (n = 2), or inflammatory (n = 9) tumor, or no (n = 16) tumor was made at surgery (n = 28) and/or a combination of biopsy (n = 9) and 9-24-month follow-up (n = 12).

RESULTS

The sensitivity was 94% for endoscopic US, 69% for CT, and 83% for MR imaging. Specificity was 100% for endoscopic US, 64% for CT, and 100% for MR imaging. Accuracy was 96% for endoscopic US, 67% for CT, and 84% for MR imaging. The sensitivity for the detection of tumors less than 3 cm in diameter was 93% for endoscopic US (n = 15), 53% for CT (n = 15), and 67% for MR imaging (n = 12).

CONCLUSION

Endoscopic US is more accurate than dynamic CT and MR imaging in the diagnosis of pancreatic tumor, particularly for tumors less than 3 cm in diameter.

MR angiographic guidance for transjugular intrahepatic portosystemic shunt procedures

The authors used magnetic resonance (MR) angiography to guide catheter placement in transjugular intrahepatic portosystemic shunt (TIPS) procedures in nine of 18 patients and compared the results with those of the nine patients for whom prior planning based on MR angiography was not done. Two-dimensional time-of-flight MR venography was performed during breath hold, and projection venograms were formatted in sagittal, coronal, and axial planes. MR angiography defined venous anatomy sufficiently to shorten the procedure and help minimize invasiveness. With MR angiographic guidance, intrahepatic needle punctures were significantly fewer (without MR guidance: mean, 12.1; with MR guidance: mean, 3.6; P < .001) and associated complications were absent (without MR guidance: failed placement, n = 1; bleeding requiring blood transfusions, n = 1; death due to intraperitoneal hemorrhage with hemobilia, n = 1; and death due to hepatic capsular perforation, n = 1). The average time for the procedure was 2.9 hours without MR angiographic guidance and 1.8 hours with MR angiographic guidance (P < .001). The authors conclude that MR angiography is a useful technique for defining portal and hepatic venous anatomy before the TIPS procedure and that planning based on MR angiography may decrease the difficulty and length of the procedure.

[The value of MR tomography after transsphenoidal hypophyseal resection. A retrospective comparison between endocrinology, operation and MRT]

Postoperative magnetic resonance images of 40 patients after transsphenoidal surgery for pituitary adenoma were evaluated retrospectively. The signal intensities of packing material and residual tumour were analysed. T1-weighted spin-echo sequences were obtained in coronal and sagittal views with and without intravenous injection of contrast media. Residual tumour demonstrated homogeneous or inhomogeneous signal intensity on the native scan with homogeneous or inhomogeneous enhancement. Packing material demonstrated a homogeneous signal intensity on the images obtained without injection of contrast media with a peripheral enhancement or alternate layers of low and intermediate signal intensity with alternate enhancement after injection of contrast media. In 5 of 54 examinations different results were found in MRI, endocrinology and surgery (two false negative and one false positive MRI in correlation with endocrinology; two residual tumours on MRI where surgery was supposed to be complete). Application of intravenous contrast media facilitates the interpretation of postoperative examination of the pituitary gland as well as comparison with preoperative examinations and the knowledge of the intraoperative procedure.

Abdominal diffusion mapping with use of a whole-body echo-planar system

PURPOSE

To measure apparent diffusion coefficients (ADCs) of water in liver, spleen, kidney, and muscle.

MATERIALS AND METHODS

Ten volunteers (seven women and three men, aged 19-31 years [mean, 24 years]) and nine patients (five women and four men, aged 49-70 years [mean, 62 years]) (liver cyst, n = 3; liver hemangioma, n = 3; liver cirrhosis, n = 2; hepatocellular carcinoma, n = 1; and liver metastasis, n = 1) underwent magnetic resonance (MR) imaging. A stimulated-echo acquisition mode (STEAM)-type excitation and echo-planar imaging (EPI) readout was used in a 1.5-T echo-planar MR imaging system.

RESULTS

ADCs measured in volunteers were liver, 1.39 x 10(-3) mm2/sec +/- 0.16; spleen, 0.95 x 10(-3) mm2/sec +/- 0.15; muscle, 1.99 x 10(-3) mm2/sec +/- 0.16; and kidney, 3.54 x 10(-3) mm2/sec +/- 0.47 (mean +/- standard deviation). Distinctive ADC values were found in organs with abnormalities. ADCs in patients with hepatic disease included liver cysts, 3.9-5.3; liver hemangiomas, 2.0-2.8; liver metastases from an islet cell tumor, 1.2; hepatocellular carcinoma, 1.7; and liver cirrhosis, 0.9-1.2 x 10(-3) mm2/sec.

CONCLUSION

In vivo diffusion measurements of abdominal organs obtained with MR imaging may prove helpful in the identification and classification of abdominal disease.

Diagnosis of severe birth asphyxia and early prediction of neonatal neurological outcome in term asphyxiated newborns

Ten indicators available during the first two hours of life, such as clinical criteria of neonatal distress and postnatal arterial blood gases, were compared with the neonatal neurological course in sixty full term newborns with significant birth asphyxia in order to test their value for the diagnosis and the short-term prognosis of severe birth asphyxia. Birth asphyxia was defined as severe when it was followed by symptoms of moderate or severe post-asphyxial encephalopathy. We calculated a sensitivity lower than fifty percent for clinical criteria such as delay in establishing regular respiration and Apgar scores. It was clear that normal delay in establishing regular respiration and normal Apgar scores do not exclude severe birth asphyxia. Arterial pH and base deficit at thirty minutes of life were found to be the best criteria for the diagnosis of severe birth asphyxia, but lacked positive predictive value. The best predictive tool for the short-term neurological prognosis of birth asphyxia was a single score established at 30 minutes of life and based on the evaluation of consciousness, respiration and neonatal reflexes. Some aspects of the pathophysiology of birth asphyxia and the rationale for treatment of post-asphyxial metabolic acidosis are discussed.

[Monitoring of fontanelle pressure in neonates and infants. Evaluation of a new measuring technique, determination of normal values and clinical usefulness]

The experience with 200 measurements of anterior fontanelle pressure with the Rotterdam Teletransducer in newborns and infants is reported. Statistical analysis of 25 comparative measurements between anterior fontanelle pressure and invasive cerebrospinal fluid pressure showed an excellent correlation (rs = 0.95). Measurements were reproducible and the plot quality allowed visualisation of pulse pressure and pressure waves. Normal values of the anterior fontanelle pressure, pulse pressure amplitude and pressure wave maximal amplitude were established in 15 prematures, 27 term newborns and 10 infants. Anterior fontanelle pressure monitoring was performed in 19 term newborns with post-asphyxial encephalopathy, 18 newborns and infants with hydrocephalus, 8 preterm and term newborns with respiratory distress and 19 patients with subdural haematomas, metabolic diseases, meningitis, subarachnoidal haemorrhage, head trauma, post cardiac arrest encephalopathy and abnormal head growth or bulging fontanelle. Abnormal patterns of anterior fontanelle pressure monitoring were found in moderate or severe neonatal post-asphyxial encephalopathy, evolutive hydrocephalus, subdural haematomas, metabolic diseases with hyperammoniemia and other clinical situations. In contrast, anterior fontanelle pressure monitoring yielded normal values in mild post-asphyxial encephalopathy, arrested hydrocephalus, well functioning ventriculo-peritoneal derivation, and in normal infants with rapid head growth or bulging fontanelle. The Rotterdam Teletransducer provides thus accurate and reproducible values of intracranial pressure. Anterior fontanelle pressure monitoring may be of value in many situations in clinical practice.

[Radiologic and ultrasound detection of gallstones]

Ultrasonography (US) is the method of choice for evaluation of gallbladder stones with an accuracy of 96%. Number, size and calcification can be assessed by virtue of US reflection and attenuation. If more than five stones are present, the accuracy decreases. To determine the calcium content of stones more precisely, computed tomography can be used. This allows an assessment of the success rate of lithotripsy and chemolysis. Oral cholecystography is an alternative method of similar accuracy as US. It provides additional information about the patency of the cystic duct. In the presence of ductal stones, the accuracy of US decreases to 30%, mainly because of overlying bowel gas. Since 8 to 16% of all cases of cholecystolithiasis are accompanied by choledocholithiasis and since this entails a change in treatment, intravenous cholecystocholangiography with an accuracy of more than 90% is the method of choice in this case. Additionally, it provides knowledge on the biliary anatomy preoperatively. It does not, however, replace US, because opacification of the gallbladder is limited with this method. If intravenous cholecystocholangiography fails in case of impaired liver function, transcholecystic cholangiography or, in cases of dilated ducts, percutaneous transhepatic cholangiography can be used. Plain film radiography is not a suitable technique, since only 10 to 15% of all gallstones calcify.

[Spontaneous rupture of the left hepatic duct]

A previously well 24-year-old man complained of persistent epigastric pain after a session of intensive muscle building exercise especially of the abdominal muscles. The abdomen was diffusely tender without guarding. There was an increased concentration of bilirubin (64.7 mumol/l), GOT (117 U/l), GPT (529 U/l) and alkaline phosphatase (150 U/l). Ultrasound examination showed a widening of the choledochal duct to 11 mm without signs of gallstones. Endoscopic retrograde cholangiography additionally revealed contrast-medium extravasation from the left hepatic duct. Computed tomography, performed immediately afterwards, confirmed the extravasation, while liver and pancreas were unremarkable. Laparoscopy revealed a 5 mm tear in the left hepatic duct, close to the hepatic duct bifurcation with bile effusion into the peritoneal cavity. The latter was rinsed endoscopically with Ringer's solution and drains were placed in the omental bursa and subhepatically in the region of the bile leak. To relax the sphincter Oddi glycerol trinitrate was administered postoperatively, for the first five days 72 mg/24 h intravenously, then for nine days twice daily 20 mg by month. No more bile drained as early as the second postoperative day and the patient was free of symptoms 2 weeks later.

[Abdominal tumors in children. A comparison between magnetic resonance tomography (MRT) and ultrasonography (US)]

Twenty-one children with predominantly solid tumours detected by US were also examined by MRI (7 neuroblastomas, 2 Wilms tumours, 3 hepatoblastomas, 2 germinal cell tumours, 1 ganglioneuroblastoma, 1 gangliocytoma, 1 Cushing's adenoma, 1 phaeochromocytoma, 1 retroperitoneal rhabdomyosarcoma, 1 diffuse lymphangiectasia of a kidney, 1 splenunculus). The findings from both methods were compared with respect to the identification of the organ involved, extent of the tumour, effect on neighbouring structures and tissue characteristics. US and MRI were of equal value in defining the origin of the lesion and in demonstrating pathological enlargement of lymph nodes. Exact tumour extent could be better demonstrated with MRI because of the ability to perform multiplanar sections and to demonstrate intrathoracic and intraspinal spread. MRI was superior in 9 cases in demonstrating tumour structure and in 6 cases in the evaluation of vascular involvement and vascular anatomy. MRI is therefore recommended as an additional method to US for diagnosis and for treatment planning.

Small-angle X-ray scattering studies of fibrin film: comparisons of fine and coarse films prepared with thrombin and ancrod

Measurements of small-angle x-ray scattering have been made on films prepared from fine and coarse (i.e., formed at high and low, respectively, pH and ionic strength) clots of bovine fibrin by osmotic shrinkage or compression in one dimension. Intensity profiles were obtained with pinhole geometry on films stretched up to a stretch ratio of 1.43. In unstretched coarse films, repeat spacings were seen at about 245, 120, and 77-80 A. These peaks can probably be identified with the first, second, and third orders of the well-known fibrin repeat of 225 A. In unstretched fine films, only the 77-80 A spacing was seen. In this case, the first two orders may be weak because the half-staggered arrangement of monomer units giving rise to the 225 A reflection is not reinforced by lateral aggregation of protofibrils; the third order may be strong since the molecular subdomains appear to divide the repeat roughly into thirds. After stretching, the 77-80 A spacing persisted in the meridional direction but almost disappeared in the equatorial. Experiments on unstretched films prepared with ancrod substituted for thrombin gave similar results.

Studies on the ultrastructure of fibrin lacking fibrinopeptide B (beta-fibrin)

Release of fibrinopeptide B from fibrinogen by copperhead venom procoagulant enzyme results in a form of fibrin (beta-fibrin) with weaker self-aggregation characteristics than the normal product (alpha beta-fibrin) produced by release of fibrinopeptides A (FPA) and B (FPB) by thrombin. We investigated the ultrastructure of these two types of fibrin as well as that of beta-fibrin prepared from fibrinogen Metz (A alpha 16 Arg----Cys), a homozygous dysfibrinogenemic mutant that does not release FPA. At 14 degrees C and physiologic solvent conditions (0.15 mol/L of NaCl, 0.015 mol/L of Tris buffer pH 7.4), the turbidity (350 nm) of rapidly polymerizing alpha beta-fibrin (thrombin 1 to 2 U/mL) plateaued in less than 6 min and formed a "coarse" matrix consisting of anastomosing fiber bundles (mean diameter 92 nm). More slowly polymerizing alpha beta-fibrin (thrombin 0.01 and 0.001 U/mL) surpassed this turbidity after greater than or equal to 60 minutes and concomitantly developed a network of thicker fiber bundles (mean diameters 118 and 186 nm, respectively). Such matrices also contained networks of highly branched, twisting, "fine" fibrils (fiber diameters 7 to 30 nm) that are usually characteristic of matrices formed at high ionic strength and pH. Slowly polymerizing beta-fibrin, like slowly polymerizing alpha beta-fibrin, displayed considerable quantities of fine matrix in addition to an underlying thick cable network (mean fiber diameter 135 nm), whereas rapidly polymerizing beta-fibrin monomer was comprised almost exclusively of wide, poorly anastomosed, striated cables (mean diameter 212 nm). Metz beta-fibrin clots were more fragile than those of normal beta-fibrin and were comprised almost entirely of a fine network. Metz fibrin could be induced, however, to form thick fiber bundles (mean diameter 76 nm) in the presence of albumin at a concentration (500 mumol/L) in the physiologic range and resembled a Metz plasma fibrin clot in that regard. The diminished capacity of Metz beta-fibrin to form thick fiber bundles may be due to impaired use or occupancy of a polymerization site exposed by FPB release. Our results indicate that twisting fibrils are an inherent structural feature of all forms of assembling fibrin, and suggest that mature beta-fibrin or alpha beta-fibrin clots develop from networks of thin fibrils that have the ability to coalesce to form thicker fiber bundles.

Effects of fibrinogen-binding tetrapeptides on mechanical properties of fine fibrin clots

The tetrapeptides Gly-Pro-Arg-Pro and Gly-His-Arg-Pro, analogs of the amino termini of the alpha and beta chains of fibrin monomer, respectively, were introduced by diffusion into fine unligated fibrin clots. Gly-Pro-Arg-Pro decreased the shear modulus of elasticity progressively and at a concentration of 5.8 mM the clot was eventually liquefied. The decrease in elastic modulus was accompanied by enormously enhanced viscoelastic creep under shear stress and irrecoverable deformation after removal of stress. However, the differential compliance (or modulus) for clots containing the tetrapeptide remained constant during creep and creep recovery, so the structure rearranged under stress without any permanent damage. Ligation with factor XIIIa and calcium largely eliminated these effects. From these changes in mechanical properties, it appears that Gly-Pro-Arg-Pro competes for binding sites, with consequent depolymerization. The tetrapeptide Gly-His-Arg-Pro at comparable concentrations decreased the modulus and increased the creep to a lesser degree; when combined with Gly-Pro-Arg-Pro it enhanced the effectiveness of the latter.

Electron microscopy of fine fibrin clots and fine and coarse fibrin films. Observations of fibers in cross-section and in deformed states

Fine fibrin clots and coarse and fine fibrin films (both ligated and unligated), formed by shrinkage of clots in one dimension, were examined by electron microscopy. Specimens of clots were prepared by critical point drying and by embedding and sectioning; specimens of films were prepared by embedding and sectioning only. In the fine clots, network junctions appeared to be formed by fiber segments in which two or more protofibrils were gently twisted around each other for distances of the order of 200 nm and then diverged to give trifunctional branch points. This topology appeared to be preserved in the fine films. It is proposed that the strength of the junctions is primarily provided by the twisting topology, though reinforced by non-covalent bonding involving the B sites uncovered by thrombin. In coarse films, bundles of protofibrils, lying primarily in the film plane, had diameters of 40 to 200 nm and were gently twisted around each other to form thicker cables. Uniaxial stretching, up to 100%, of either fine or coarse film before fixing caused suprisingly extensive orientation of the protofibrils or bundles. However, random orientation was recovered if a stretched ligated film was allowed to retract to its original dimensions before fixing. In a stretched coarse film sectioned perpendicular to the stretch direction, fiber bundles could be seen in cross-section; these were roughly circular with scalloped edges. The changes with stretching and recovery are discussed in relation to possible mechanisms of deformation and elastic energy storage.