The neglected role of relative humidity in the interannual variability of urban malaria in Indian cities

The rapid pace of urbanization makes it imperative that we better understand the influence of climate forcing on urban malaria transmission. Despite extensive study of temperature effects in vector-borne infections in general, consideration of relative humidity remains limited. With process-based dynamical models informed by almost two decades of monthly surveillance data, we address the role of relative humidity in the interannual variability of epidemic malaria in two semi-arid cities of India. We show a strong and significant effect of humidity during the pre-transmission season on malaria burden in coastal Surat and more arid inland Ahmedabad. Simulations of the climate-driven transmission model with the MLE (Maximum Likelihood Estimates) of the parameters retrospectively capture the observed variability of disease incidence, and also prospectively predict that of 'out-of-fit' cases in more recent years, with high accuracy. Our findings indicate that relative humidity is a critical factor in the spread of urban malaria and potentially other vector-borne epidemics, and that climate change and lack of hydrological planning in cities might jeopardize malaria elimination efforts.

Temporally Distinct Roles for the Zinc Finger Transcription Factor Sp8 in the Generation and Migration of Dorsal Lateral Ganglionic Eminence (dLGE)-Derived Neuronal Subtypes in the Mouse

Progenitors in the dorsal lateral ganglionic eminence (dLGE) are known to give rise to olfactory bulb (OB) interneurons and intercalated cells (ITCs) of the amygdala. The dLGE enriched transcription factor Sp8 is required for the normal generation of ITCs as well as OB interneurons, particularly the calretinin (CR)-expressing subtype. In this study, we used a genetic gain-of-function approach in mice to examine the roles Sp8 plays in controlling the development of dLGE-derived neuronal subtypes. Misexpression of Sp8 throughout the ventral telencephalic subventricular zone (SVZ) from early embryonic stages, led to an increased generation of ITCs which was dependent on Tshz1 gene dosage. Additionally, Sp8 misexpression impaired rostral migration of OB interneurons with clusters of CR interneurons seen in the SVZ along with decreased differentiation of calbindin OB interneurons. Sp8 misexpression throughout the ventral telencephalon also reduced ventral LGE neuronal subtypes including striatal projection neurons. Delaying Sp8 misexpression until E14-15 rescued the striatal and amygdala phenotypes but only partially rescued OB interneuron reductions, consistent with an early window of striatal and amygdala neurogenesis and ongoing OB interneuron generation at this late stage. Our results demonstrate critical roles for the timing and neuronal cell-type specificity of Sp8 expression in mouse LGE neurogenesis.

Impact of intraprocedural stent thrombosis on outcomes of percutaneous coronary intervention: a meta-analysis

Background

Intraprocedural stent thrombosis (IPST), defined as the development of occlusive or nonocclusive new thrombus in or adjacent to a recently implanted stent before completion of PCI. IPST even though a rare entity, yet is associated with worse prognosis amongst all intraprocedural thrombotic events.

Purpose

Data regarding the impact of IPST is scarce and needs further investigation.

Methods

We performed literature search of all published full-length articles that studied and compared data on patients with IPST and with no IPST during PCI. We calculated odds ratios via the random effects model for 30 day and 1 year outcomes.

Results

Our literature search yielded 3 studies (1 retrospective, 2 observational post-hoc analysis) relevant to the meta-analysis. Total 19272 patients were included. IPST occurred in 159 patients (0.8%). At 30 days, IPST was associated with statistically significant higher all-cause mortality (OR 10.79, 95% CI [6.31, 18.45] p<0.00001), MI (OR 4.82, 95% CI [2.39, 9.73] p<0.0001), target vessel revascularization (TVR) (OR 6.70, 95% CI [3.38, 13.29] p<0.00001), definite stent thrombosis (OR 10.44, 95% CI [5.87, 18.58] p<0.00001), definite or probable stent thrombosis (OR 9.28), 95% CI [5.54, 15.56] p<0.00001) and death or MI or TVR (OR 7.20], 95% CI [4.10, 12.64] p<0.00001), than those without IPST. At one year, results remained statistically significant for higher mortality (OR 4.27, 95% CI [1.92, 9.49] p=0.0004) and death or MI or TVR (OR 2.91, 95% CI [1.58, 5.36] p=0.0006) in patients with IPST.

Conclusions

IPST even though is a rare occurrence, is associated with more adverse ischemic events, including higher mortality at 30 days and 1 year.

Funding Acknowledgement

Type of funding source: None

Foxo1 is a downstream effector of Isl1 in direct pathway striatal projection neuron development within the embryonic mouse telencephalon

Recent studies have shown that the LIM-homeodomain transcription factor Isl1 is required for the survival and differentiation of direct pathway striatonigral neurons during embryonic development. The downstream effectors of Isl1 in these processes are presently unknown. We show here that Foxo1, a transcription factor that has been implicated in cell survival, is expressed in striatal projection neurons (SPNs) that derive from the Isl1 lineage (i.e. direct pathway SPNs). Moreover, Isl1 conditional knockouts (cKOs) show a severe loss of Foxo1 expression at E15.5 with a modest recovery by E18.5. Although Foxo1 is enriched in the direct pathway SPNs at embryonic stages, it is expressed in both direct and indirect pathway SPNs at postnatal time points as evidenced by co-localization with EGFP in both Drd1-EGFP and Drd2-EGFP BAC transgenic mice. Foxo1 was not detected in striatal interneurons as marked by the transcription factor Nkx2.1. Conditional knockout of Foxo1 using Dlx5/6-CIE mice results in reduced expression of the SPN marker Darpp-32, as well as in the direct pathway SPN markers Ebf1 and Zfp521 within the embryonic striatum at E15.5. However, this phenotype improves in the conditional mutants by E18.5. Interestingly, the Foxo family members, Foxo3 and Foxo6, remain expressed at late embryonic stages in the Foxo1 cKOs unlike the Isl1 cKOs where Foxo1/3/6 as well as the Foxo1/3 target Bach2 are all reduced. Taken together, these findings suggest that Foxo-regulated pathways are downstream of Isl1 in the survival and/or differentiation of direct pathway SPNs.

Successful management of primary nontuberculous mycobacterial infection of hepatic allograft following orthotopic liver transplantation for hepatitis C

Nontuberculous mycobacteria are a rare cause of disease in solid organ and hematopoietic stem cell transplant recipients. The impact of mycobacterial infections in transplant recipients necessitates prompt diagnosis and early initiation of therapy. However, diagnosis remains difficult and there is a lack of specific recommendations for the choice of anti-mycobacterial drugs, duration of therapy, and monitoring of graft function as well as immunosuppression in these patients. Issues involved in the management are illustrated by an index case of hepatic allograft infection due to Mycobacterium avium complex.

Image contrast in X-ray reflection interface microscopy: comparison of data with model calculations and simulations

The contrast mechanism for imaging molecular-scale features on solid surfaces is described for X-ray reflection interface microscopy (XRIM) through comparison of experimental images with model calculations and simulated measurements. Images of elementary steps show that image contrast is controlled by changes in the incident angle of the X-ray beam with respect to the sample surface. Systematic changes in the magnitude and sign of image contrast are asymmetric for angular deviations of the sample from the specular reflection condition. No changes in image contrast are observed when defocusing the condenser or objective lenses. These data are explained with model structure-factor calculations that reproduce all of the qualitative features observed in the experimental data. These results provide new insights into the image contrast mechanism, including contrast reversal as a function of incident angle, the sensitivity of image contrast to step direction (i.e. up versus down), and the ability to maximize image contrast at almost any scattering condition defined by the vertical momentum transfer, Q(z). The full surface topography can then, in principle, be recovered by a series of images as a function of incident angle at fixed momentum transfer. Inclusion of relevant experimental details shows that the image contrast magnitude is controlled by the intersection of the reciprocal-space resolution function (i.e. controlled by numerical aperture of the condenser and objective lenses) and the spatially resolved interfacial structure factor of the object being imaged. Together these factors reduce the nominal contrast for a step near the specular reflection condition to a value similar to that observed experimentally. This formalism demonstrates that the XRIM images derive from limited aperture contrast, and explains how non-zero image contrast can be obtained when imaging a pure phase object corresponding to the interfacial topography.

GATE: a simulation toolkit for PET and SPECT

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

GATE: a simulation toolkit for PET and SPECT

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

Comparison of ministernotomy with minithoracotomy regarding postoperative pain and internal mammary artery characteristics

PURPOSE

This prospective clinical study focuses on postoperative pain and internal mammary artery (IMA) characteristics after ministernotomy versus left anterior minithoracotomy.

METHOD

Patients were studied in two groups. Group A consisted of 267 consecutive single vessel (IMA to left anterior descending artery (LAD)) minimally invasive direct coronary artery bypass (MIDCAB) patients using ministernotomy from the tip of the xiphoid to the fourth intercostal space. Group B consisted of the same number of MIDCAB patients operated on through anterolateral minithoracotomy. Pain was graduated using the visual analog scale (VAS). Internal mammary artery (IMA) characteristics were compared in both the groups.

RESULTS

Postoperative pain was not significant statistically on postop day (POD) 1 in either of the groups (p = 0.07). From POD 2 onwards Group A patients had less pain than Group B patients (p < 0.05), and the pain medication requirement from POD 2 onwards was less in Group A than in Group B. Length of harvested IMA was 15.6 +/- 2.1 cm in Group A as compared to 10.4 +/- 2.2 cm in Group B (p < 0.05). Free flow of IMA in group A was 56 +/- 16 ml/min., whereas in Group B the flow was 50 +/- 14 ml/min. (p = 0.04).

CONCLUSION

Compared to patients undergoing MIDCAB using ministernotomy, anterolateral minithoracotomy patients suffer more pain from POD 2 onwards and their postoperative pain medication requirement is also higher. Length and free flow of IMA is better in patients operated on for MIDCAB using ministernotomy. Thus, ministernotomy is a better approach than minithoracotomy in terms of postoperative pain and IMA characteristics for single-vessel MIDCAB patients.

Calmodulin binding to the C-terminus of the small-conductance Ca2+-activated K+ channel hSK1 is affected by alternative splicing

We identified three splice variants of hSK1 whose C-terminal structures are determined by the independent deletion of two contiguous nucleotide sequences. The upstream sequence extends 25 bases in length, is initiated by a donor splice site within exon 8, and terminates at the end of the exon. The downstream sequence consists of nine bases that compose exon 9. When the upstream sequence (hSK1(-)(25b)) or both sequences (hSK1(-)(34b)) are deleted, truncated proteins are encoded in which the terminal 118 amino acids are absent. The binding of calmodulin to these variants is diminished, particularly in the absence of Ca2+ ions. The first 20 amino acids of the segment deleted from hSK1(-)(25b) and hSK1(-)(34b) contain a 1-8-14 Ca2+ calmodulin binding motif, and synthetic oligopeptides based on this region bind calmodulin better in the presence than absence of Ca2+ ions. When the downstream sequence (hSK1(-)(9b)) alone is deleted, only the three amino acids A452, Q453, and K454 are removed, and calmodulin binding is not reduced. On the basis of the relative abundance of mRNA encoding each of the four isoforms, the full-length variant appears to account for most hSK1 in the human hippocampus, while hSK1(-)(34b) predominates in reticulocytes, and hSK1(-)(9b) is especially abundant in human erythroleukemia cells in culture. We conclude that the binding of calmodulin by hSK1 can be modulated through alternative splicing.

Discrete subvalvular aortic stenosis in adults

Discrete subvalvular aortic stenosis is a relatively rare condition in adults. It is often diagnosed during first decade of life especially in association with other congenital malformations. Isolated form of discrete subvalvular aortic stenosis may however silently progress from innocent murmurs of childhood and adolescence to symptomatic left ventricular outflow tract obstruction in adults. Certain overt and subtle morphological abnormalities may underlie the initial expression as well as high recurrence rates after surgical resection of sub aortic membrane. Though surgical resection is the only treatment available, debate on the surgical technique and appropriate timing of surgery continues. Close followup with serial echocardiographic examinations in patients detected to have functional murmurs during childhood may be helpful in early detection of subvalvular aortic stertosis.

Discrete subvalvular aortic stenosis

Discrete Subaortic Stenosis is one of the many lesions responsible for left ventricular outflow tract (LVOT) obstruction. It may present as in an isolated from as membranous or fibromuscular ring below the aortic valve or in association with other congenital anamolies such as VSD, PDA, coarctation of aorta, hypoplastic aortic annulus, double chamber right ventricle among others. The condition is rarely diagnosed antenataly or in infancy but often manifests in the first decade of life with features of progressive LVOT obstruction, LV hypertrophy and dysfunction aortic regurgitation due to damage to the aortic cusps because of the jet from the subaortic narrowing which may also render the aortic valve prone to infective endocarditis. Interaction of genetic predisposition and morphologically deformed long and narrow LVOT cause rheological abnormalities and increased shear stress in the region of subaortic stenosis and seem to be the main etiological factor alongwith poorly defined role of more extensive but subtle changes in the LV endocardium. Condition can be easily diagnosed by cross-sectional and Doppler echocardiography and confirmed by demonstrating a pressure gradient below aortic valve on cardiac catheterisation and LV angiography. Surgical membranectomy alongwith myotomy or myomectomy remain the mainstay of treatment but long term results are not satisfactory as there is a high rate of recurrences requiring reoperations. A close follow up with serial echocardiographic examinations is very helpful in early detection of subaortic obstruction in patients who have so called functional murmurs in the childhood.

Calpain inhibition prevents sinusoidal endothelial cell apoptosis in the cold ischemic rat liver

BACKGROUND

Cold preservation of the liver followed by reperfusion results in sinusoidal endothelial cell (SEC) apoptosis. Calpain-like activity is dramatically increased during reperfusion and inhibition of calpains results in lower graft injury and longer survival. Recently, calpains have been implicated in inducing apoptosis. Our aim was to determine the effect of calpain inhibition on SEC apoptosis.

METHODS

Livers were stored in the University of Wisconsin solution for 24 hr (survival conditions) and 40 hr (nonsurvival conditions) and ex vivo reperfused for 1 hr at 37 degrees C. Calpain-like activity was inhibited in some experiments using an i.p. injection of a selective inhibitor 2 hr before explantation. Apoptosis was quantified using the terminal deoxynucleotidyl trans. ferase-mediated dUTP nick end-labeling assay. Cross-inhibition by the inhibitor was determined for caspases 1 and 3.

RESULTS

Apoptosis of exclusively the SEC was a key feature of reperfusion injury after both storage periods in University of Wisconsin solution after 1 hr normothermic reperfusion. Inhibition of calpain activity with Cbz-Val-Phe methyl ester resulted in a 50% reduction of apoptotic SEC in the 40-hr preserved liver, and an almost complete abrogation of SEC apoptosis after 24 hr preservation. Only minimal cross-inhibition of caspases was determined at high concentrations in vitro by the calpain inhibitor.

CONCLUSION

Apoptosis of exclusively SEC is a key feature of reperfusion injury partially mediated through calpain-dependent processes. Calpain inhibition reduces the number of apoptotic SEC. Based on these data and our previous work, calpain inhibition may prove to be useful in clinical transplantation.

Paired ventricular pacing: an alternative therapy for postoperative junctional ectopic tachycardia in congenital heart disease

Junctional ectopic tachycardia (JET) is one of the most life-threatening postoperative arrhythmias in children with congenital heart disease, and medical management is difficult. Paired ventricular pacing (PVP) may provide a safe alternative mode of management. We evaluated the safety and efficacy of PVP for the management of postoperative JET in patients with congenital heart disease. A retrospective collection of data was done from 1981-1995. PVP was successfully tried in five postoperative patients (age range: 37 days to 22 years, median: 10 months). Onset of JET was 3-60 hours (mean +/- SD, 19 +/- 23 hours) postoperatively. The maximal JET rate was 261 +/- 39 beats/min. PVP was used as the first line of management in three patients and was successful in all patients. It resulted in an instantaneous increase in blood pressure from 66 +/- 9 to 94 +/- 15 mmHg (42% increase) and was required for 12 +/- 14 hours (range 2-36 hours). No complications were noted. Therefore, in our experience, this is a safe alternative modality for the control of postoperative JET.

Endothelial cell and hepatocyte deaths occur by apoptosis after ischemia-reperfusion injury in the rat liver

BACKGROUND

Ischemic injury of the liver is generally considered to result in necrosis, but it has recently been recognized that mediators of apoptosis are activated during ischemia/reperfusion. This study was designed to characterize the extent and the type of cells within the liver that undergo apoptosis at different periods of ischemia and reperfusion.

METHODS

Male Wistar rats were subjected to 30 or 60 min of normothermic ischemia. Liver sections were evaluated at the end of ischemia and at 1, 6, 24, and 72 hr after reperfusion. Apoptosis was determined by DNA fragmentation as evaluated by laddering on gel electrophoresis, in situ staining for apoptotic cells using TdT-mediated dUTP-digoxigenin nick-end labeling (TUNEL), and morphology on electron microscopy.

RESULTS

In situ staining of liver biopsy specimens using TUNEL showed significant apoptosis after reperfusion. Sinusoidal endothelial cells (SEC) showed evidence of apoptosis earlier than hepatocytes. For example, at 1 hr of reperfusion after 60 min of ischemia, 22+/-4% of the SEC stained TUNEL positive compared with 2+/-1% of the hepatocytes (P<0.001). With a longer duration of ischemia, a greater number of SEC and hepatocytes became TUNEL positive. An increase in TUNEL-positive cells was also noted with an increasing duration of reperfusion. The presence of apoptotic SEC and hepatocytes was supported by DNA laddering on gel electrophoresis and cell morphology on electron microscopy. Several Kupffer cells were seen containing apoptotic bodies but did not show evidence of apoptosis. Only rare hepatocytes showed features of necrosis after 60 min of ischemia and 6 hr of reperfusion.

CONCLUSION

These results suggest that apoptosis of endothelial cells followed by hepatocytes is an important mechanism of cell death after ischemia/reperfusion injury in the liver.

Controlled ventilation enhances catheter stability during radiofrequency ablation

Variations in the amplitude of the atrial and ventricular depolarization waves of the intracardiac electrogram occur during different phases of respiration. Therefore, we tested whether controlled ventilation would reduce ablation attempts and increase the rate of success in patients undergoing radiofrequency ablation with general anesthesia. Thirty-eight children were divided into two groups: (1) controlled and (2) noncontrolled or cyclic ventilation. In the controlled ventilation group, the mapping electrogram was recorded during sustained inspiration, sustained expiration, and cyclic ventilation. Ablation was done in the phase of ventilation that had the least variability in atrial and ventricular amplitudes. Seventeen patients in the controlled ventilation group had tracings adequate for review. In eight patients, ablation was done during sustained inspiration with the percentage change of atrial and ventricular amplitudes (15% +/- 16% and 13% +/- 16%, respectively) being < that during sustained expiration (38% +/- 27%, P = 0.04 and 20% +/- 21%) or during cyclic ventilation (57% +/- 27%, P < 0.01 and 54% +/- 26%, P = 0.003). In nine patients, ablation was done during sustained expiration with the percentage change of atrial and ventricular amplitudes (5% +/- 5% and 5% +/- 2%) being less than that during sustained inspiration (21% +/- 14%, P = 0.01 and 11% +/- 6%, P = 0.01) or during cyclic ventilation (68% +/- 23%, P < 0.001 and 48 +/- 26%, P = 0.001). We achieved success with each patient in both groups, but the number of ablation attempts were less in the controlled ventilation group 1 (3 +/- 2), as compared to the cyclic ventilation group 2 (8 +/- 8; P < 0.02). We concluded that controlled ventilation reduced the number of ablation attempts and facilitated the ablation procedure.

Calpain mediates ischemic injury of the liver through modulation of apoptosis and necrosis

BACKGROUND & AIMS

Calpain proteases have been implicated in cell death by necrosis and more recently by apoptosis. Experiments were designed to determine the role of calpain proteases in ischemic rat liver injury by measurement of cytosolic calpain activity after different periods of ischemia-reperfusion and by evaluation of the effects of calpain inhibition on tissue injury and animal survival.

METHODS

Calpain activity was measured in the cytosol using Suc-Leu-Leu-Val-Try-7 amino-4 methyl coumarin, a specific fluorogenic substrate, and Cbz-Leu-Leu-Tyr-CHN2, a specific inhibitor.

RESULTS

Calpain activity increased significantly with the duration of ischemia-reperfusion and was inhibited more than 80% by the inhibitor. Calpain inhibition resulted in a significant decrease in transaminase release and tissue necrosis and converted nonsurvival ischemic conditions to survival conditions. When the in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling assay for apoptosis was used, 35% +/- 6% of nonparenchymal cells and 16% +/- 3% of hepatocytes stained positively after 60 minutes of ischemia and 6 hours of reperfusion. In contrast, animals pretreated with the calpain inhibitor showed minimal evidence of apoptosis. This was further substantiated by gel electrophoresis assay for DNA fragmentation and by electron-microscopic evaluation.

CONCLUSIONS

These data suggest that calpain proteases play a pivotal role in warm ischemia-reperfusion injury of the rat liver through modulation of apoptosis and necrosis.

The effect of native-language retention and insecurity on Asian Indian fertility in the United States

The relationship of social/psychological insecurity and native-language retention to fertility was explored among a nationally representative sample of 3,408 endogamously wed Asian Indian women living in the United States. Native-language retention had a negative impact on Asian Indian women's fertility that cannot be explained by the normative dimension of the minority group status hypothesis (Goldscheider & Uhlenberg, 1969); therefore, alternative explanations for minority fertility differentials are required.

Comparison of frequency-distance relationship and Gaussian-diffusion-based methods of compensation for distance-dependent spatial resolution in SPECT imaging

The goal of this investigation was to compare resolution recovery versus noise level of two methods for compensation of distance-dependent resolution (DDR) in SPECT imaging. The two methods of compensation were restoration filtering based on the frequency-distance relationship (FDR) prior to iterative reconstruction, and modelling DDR in the projector/backprojector pair employed in iterative reconstruction. FDR restoration filtering was computationally faster than modelling the detector response in iterative reconstruction. Using Gaussian diffusion to model the detector response in iterative reconstruction sped up the process by a factor of 2.5 over frequency domain filtering in the projector/backprojector pair. Gaussian diffusion modelling resulted in a better resolution versus noise tradeoff than either FDR restoration filtering or solely modelling attenuation in the projector/backprojector pair of iterative reconstruction. For the pixel size investigated herein (0.317 cm), accounting for DDR in the projector/backprojector pair by Gaussian diffusion, or by applying a blurring function based on the distance from the face of the collimator at each distance, resulted in very similar resolution recovery and slice noise level.

Influence of OSEM, elliptical orbits and background activity on SPECT 3D resolution recovery

In maximum-likelihood expectation-maximization (MLEM) reconstruction of SPECT images, if both attenuation correction (AC) and detector response correction (DRC) are included, the reconstruction can be too time consuming to be clinically useful. With use of the ordered-subset expectation-maximization (OSEM) reconstruction, it has been reported that the reconstruction time can be substantially reduced. We investigated the reconstruction of point sources in a non-uniform attenuation medium in terms of the normalized FWHM of these sources. We compared MLEM versus OSEM reconstructions; circular versus elliptical orbits; and the presence versus the absence of background activity in the object. We found: (i) that OSEM does speed up the reconstruction by a factor of 10 over MLEM; (ii) that the resolution recovery does not depend on the type of orbit if both AC and DRC are included in the reconstruction; however, when there is background activity, a significant number of iterations are required to alleviate the effect of orbit; (iii) that background activity significantly slows down the resolution recovery of the point sources; and (iv) that if reconstruction only includes AC, and not DRC, changing orbit can change isotropy of recovered resolution, whereas introducing background activity may degrade the recovered resolution and also changes the isotropy.

Coronary artery bypass surgery without cardiopulmonary bypass: short- and mid-term results

From March 1994 to April 1997, 433 patients had undergone coronary artery bypass grafting without cardiopulmonary bypass in our institute. Sixty-eight patients had various organ dysfunctions and/or aortic atheroma or calcification and were regarded as high risk for cardiopulmonary bypass. In 277 patients surgery was performed through midline sternotomy, while in 156 minithoracotomy approach was used. In 361 patients single coronary artery bypass grafting was done, and in 72 two-coronary arteries were bypassed. In 63 patients who had graftable vessels in anterior wall and diffusely diseased ungraftable vessels in posterolateral and/or inferior wall, transmyocardial laser revascularisation was also done along with coronary artery bypass grafting to achieve complete myocardial revascularisation. Nine patients in this series were also subjected to simultaneous carotid endarterectomy along with myocardial revascularisation. In two patients complementary percutaneous transluminal coronary angioplasty of left circumflex coronary artery was done five days after minithoracotomy and left internal mammary artery to left anterior descending coronary artery bypass grafting. Forty-two cases were extubated in operating room. Average blood loss was 260 ml. Six patients were reexplored for postoperative bleeding. Seven patients had perioperative myocardial infarction. One developed neurological complication. Hospital mortality was 2.3 percent (10/433 cases) and four deaths were due to malignant ventricular arrhythmias. Nine patients developed chest wound complications. Average hospital stay after operation was six days, 423 patients were discharged from hospital and all of them were asymptomatic. During three years follow-up (range 3 to 38 months) there were three known cardiac deaths. Ninety percent (391) patients reported to the follow-up clinic and 91 percent of them were angina-free. In patients who were subjected to transmyocardial laser revascularisation along with coronary artery bypass grafting, myocardial perfusion scan showed a step-wise improvement in reversible ischemia. The perfusion index increased from 52 percent at three months to 90 percent at 12 months. We conclude that coronary artery bypass grafting without cardiopulmonary bypass can be done with relatively low mortality, more so in a group of patients in whom cardiopulmonary bypass poses a high risk. Transmyocardial laser revascularisation is a suitable means to provide complete myocardial revascularisation along with coronary artery bypass surgery in patients who have graftable vessels in anterior wall and ungraftable vessels in posterolateral and inferior walls.

Calpain is a mediator of preservation-reperfusion injury in rat liver transplantation

Proteases as well as alterations in intracellular calcium have important roles in hepatic preservation-reperfusion injury, and increased calpain activity recently has been demonstrated in liver allografts. Experiments were designed to evaluate (i) hepatic cytosolic calpain activity during different periods of cold ischemia (CI), rewarming, or reperfusion, and (ii) effects of inhibition of calpain on liver graft function using the isolated perfused rat liver and arterialized orthotopic liver transplantation models. Calpain activity was assayed using the fluorogenic substrate Suc-Leu-Leu-Val-Tyr-7-amino-4-methyl coumarin (AMC) and expressed as mean +/- SD pmol AMC released/min per mg of cytosolic protein. Calpain activity rose significantly after 24 hr of CI in University of Wisconsin solution and further increased with longer preservation. Activity also increased within 30 min of rewarming, peaking at 120 min. Increased durations of CI preceding rewarming resulted in significantly higher activity (P < 0.01). Calpain activity increased rapidly upon reperfusion and was significantly enhanced by previous CI (P < 0.01). Calpain inhibition with Cbz-Val-Phe methyl ester significantly decreased aspartate aminotransferase released in the isolated perfused rat liver perfusate (P < 0.05). Duration of survival after orthotopic liver transplantation using livers cold-preserved for 40 hr was also significantly increased (P < 0.05) with calpain inhibitor. In conclusion, calpain proteases are activated during each phase of transplantation and are likely to play an important role in the mechanisms of preservation-reperfusion injury.

Similar time-dependent recovery property of fast and slow atrioventricular nodal pathways

The purpose of this study was to determine whether fast and slow atrioventricular (AV) nodal pathways have the same recovery property. AV nodal recovery property is studied by delivering atrial extrastimuli coupled to atrial beats and plotting nodal coupling intervals against nodal conduction time. In patients with dual pathways the resultant curves will include a fast to fast (F-F) and a fast to slow (F-S) pathway coupled curves. Although fast pathway recovery property can be represented by the former, slow pathway recovery property requires further assessment by studying slow to slow (S-S) pathways coupled curve. In 9 patients with dual pathways F-F, F-S, S-F, and S-S curves were obtained by pacing protocols. In 8 patients (control) without dual pathways, F-F curve and atrial extrastimuli coupled to a preceding slowly conducted fast pathway beat (also designated as S-F curve) were obtained. (1) The S-S curve had a similar time constant as the F-F curve. (2) Although the S-S curve was markedly shifted upward and leftward from the F-F curve, the degree of leftward and upward shifts of the S-S curve from the F-F curve were both close to the difference of the basic fast and slow pathway conduction time (a constant). (3) Although the effective refractory period of the fast pathway in dual pathway patients was longer than that of the control patients, the slow pathway effective refractory period when corrected was close to that of fast pathway in control patients. These results suggest that the fast and slow AV nodal pathways have a similar time-dependent recovery property.

The birth order factor: ordinal position, social strata, and educational achievement

The relationship between birth order and academic attainment of 817 men and women from a variety of socioeconomic backgrounds in the United States was explored. A measure of respondents' family economic situation during their growing-up years was incorporated. Birth order was found to have an impact on total years of education completed among members of the middle class. The observed patterns also indicate that "only" children, contrary to findings of previous research, appear disproportionately to excel in terms of educational attainment. These findings support a resource-dilution hypothesis.

Proximal splenorenal shunts for extrahepatic portal venous obstruction in children

OBJECTIVE

The results of proximal splenorenal shunts done in children with extrahepatic portal venous obstruction were evaluated.

SUMMARY BACKGROUND DATA

Extrahepatic portal venous obstruction, a common cause of portal hypertension in children in India, is being treated increasingly by endoscopic sclerotherapy instead of by proximal splenorenal shunt. It is believed that surgery (or the operation) carries high mortality and rebleeding rates and is followed by portosystemic encephalopathy and postsplenectomy sepsis. However, a proximal splenorenal shunt is a definitive procedure that may be more suitable for children, particularly those who have limited access to medical facilities and safe blood transfusion.

METHODS

Between 1976 and 1992, the authors performed 160 splenorenal shunts in children. Twenty were emergency procedures for uncontrollable bleeding and 140 were elective procedures--102 for recurrent bleeding and 38 for hypersplenism.

RESULTS

The overall operative mortality rate was 1.9%--10% (3/160-2/20) after emergency operations and 0.7% (1/140) after elective operations. Rebleeding occurred in 17 patients (11%), and pneumococcal meningitis developed in 1 patient who recovered later. Encephalopathy did not develop in any patient. Four patients died in the follow-up period--two of rebleeding, one of chronic renal failure and a subphrenic abscess, and one of unknown causes. The 15-year survival rate by life table analysis was 95%.

CONCLUSIONS

A proximal splenorenal shunt, a one-time procedure with a low mortality rate and good long-term results, is an effective treatment for children in India with extrahepatic portal venous obstruction.

Management of hepatic venous outflow obstruction

Hepatic venous outflow obstruction (HVOO) is a rare cause of portal hypertension and conservative treatment is usually ineffective. A large series of patients gave us an opportunity to devise a management protocol for this disorder. Between 1978 and 1992, we prospectively studied 75 patients with HVOO. The obstruction was in the hepatic vein in 24, in the inferior vena cava (IVC) in 44, and in both in 7. For hepatic vein obstruction proximal splenorenal shunts were done in 7 (2 died postoperatively); 4 shunts blocked and only 1 patient became completely symptom free. In 2 patients with partial obstruction we performed balloon dilatation of the right hepatic veins but within 6 months the obstruction recurred. In the next 6 patients we constructed a side-to-side portocaval shunt; 2 died of encephalopathy after discharge and 4 are alive and well. For IVC obstruction, after surgical procedures had yielded poor results in 14 patients, we changed to balloon angioplasty which was successful in 28 of the 30 other patients; restenosis occurred in 4. Of the 7 patients with a combined block, 3 have had balloon angioplasty followed by a side-to-side portocaval shunt; 1 died, 2 are well, and the remainder have not completed treatment. Of our 75 patients, 22 have died (5 in hospital and 17 after discharge), 7 have not completed treatment, and 2 have been lost to follow-up. However, 44 are symptom free. We did not encounter any case of hepatocellular carcinoma. We suggest that patients with HVOO should be actively managed with a side-to-side portocaval shunt for hepatic vein obstruction, balloon angioplasty for inferior vena caval obstruction, and perhaps both procedures for those with combined obstructions.

Biological properties and growth in SCID mice of a new myelogenous leukemia cell line (KBM-5) derived from chronic myelogenous leukemia cells in the blastic phase

The establishment and the biological properties of a new leukemic cell line (KBM-5) derived from a patient in the blastic phase of chronic myelogenous leukemia are described. The cells exhibited multiple copies of the Philadelphia chromosome, and a high level of p210Bcr-Abl kinase activity was detected with rabbit anti-Abl and anti-Bcr (exon 3) peptide antisera. Use of specific primers and polymerase chain reaction followed by Southern blotting revealed that KBM-5 cells carried a bcr3-ABLII splice junction. While a normal BCR message was detected, no normal ABL message was found. The cells were phenotypically myeloid with monocytic differentiation. The high cloning efficiency in semisolid media was independent of the presence of exogenous colony-stimulating factors. In vitro exposure to induces of differentiation, such as retinoic acid, dimethyl sulfoxide, or hemin, failed to influence the growth rate of the cells and their level of differentiation. KBM-5 cells are highly resistant to the antiproliferative action of recombinant alpha- and gamma-interferons. Although sensitive to recombinant tumor necrosis factor alpha, they were completely resistant to natural killer cell action. KBM-5 cells constitutively expressed mRNA for tumor necrosis factor alpha but not for gamma-interferon, other interleukins, or hematopoietic growth factors. The KBM-5 cells that were transplanted into SCID mice manifested metastatic potential and tissue invasiveness similar to the way leukemic cells in humans do. This new KBM-5 cell line represents a helpful model for examining in vitro and in vivo modulation of the growth and properties of leukemic cells by using biological and chemotherapeutic agents.

Comparison of in vitro transcriptions using various types of DNA templates

Improvements in the synthesis of RNA using T7 RNA polymerase and synthetic deoxyoligonucleotides containing the T7 RNA promoter are described. Yields were highest when the double-stranded promoter was generated from a hairpin hybridized to the single-stranded DNA template or when the templates were assembled by ligation of shorter chemically synthesized deoxyoligonucleotides. Our results show that for the synthesis of RNA, templates prepared by ligating smaller deoxyoligonucleotides were as much as 25 times more efficient than those prepared by one-step chemical synthesis.

Value of serum C-reactive protein concentrations in febrile children without apparent focus

We examined the value of serum C-reactive protein (CRP) in febrile children without an apparent focus of infection, (i) as a tool to differentiate bacteraemia and bacterial infection from a non-bacterial illness (NBI), and (ii) as an indicator of recovery or complications. Included in the study were 100 children up to the age of 3 years with a temperature of > or = 38.5 degrees C, without an apparent focus. The serum CRP concentration was measured on days 1, 3 and 5 of evaluation and correlated with the final diagnosis and outcome. The serum CRP was 40 mg/l and above in 95% of patients (18/19) with bacteraemia and also in seven of the eight with purulent meningitis, while it was < 40 mg/l in 84% of patients (52/62) with NBI (mean (SD) 22 (28.6) mg/l). The mean serum CRP concentration among six children with a culture-positive urinary tract infection (16.3 (8.3) mg/l) and five with otitis media (9 (5.7) mg/l) was similar to those with NBI. The sensitivity of serum CRP > or = 40 mg/l for diagnosis of bacteraemia was 95% and the positive predictive value 67%. On serial monitoring, a fall in the CRP concentration was a sensitive indicator of recovery from infection and provided the earliest clue to therapeutic response long before a fall in temperature.