Determinants of growth in children with the obstructive sleep apnea syndrome

Failure to thrive is a common complication of childhood obstructive sleep apnea syndrome (OSAS). To further evaluate its cause, we obtained 3-day dietary records, anthropometric measurements, polysomnography, and measurements of energy expenditure during sleep (SEE) in children with OSAS before and after tonsillectomy and adenoidectomy. Fourteen children were studied (mean age, 4 +/- 1 (SD) years). During initial polysomnography, patients had 6 +/- 3 episodes of obstructive apnea/hr, an arterial oxygen saturation nadir of 85% +/- 8%, and peak end-tidal carbon dioxide tension of 52 +/- 6 mm Hg. After surgery, OSAS resolved in all patients. The standard deviation score (z score) for weight increased from -0.30 +/- 1.47 to 0.04 +/- 1.34 (p < 0.005), despite unaltered caloric intake (91 +/- 30 vs 90 +/- 27 kcal/kg per day; not significant). The initial SEE (averaged over all sleep states) was 51 +/- 6 kcal/kg per day; postoperatively, it decreased to 46 +/- 7 kcal/kg per day (p < 0.005). Although SEE decreased during all sleep stages, the greatest decrease occurred during rapid eye movement sleep. The patients with the highest SEE on initial study had the lowest z scores (r = -0.62; p < 0.05). We conclude that SEE decreases and weight improves after resolution of OSAS. We speculate that the poor growth seen in some children with OSAS is secondary to increased caloric expenditure caused by increased work of breathing during sleep.

Improving medical emergency team (MET) performance using a novel curriculum and a computerized human patient simulator

PROBLEM

Advance cardiac life support (ACLS) training does not address coordination of team resources to improve the ability of teams to deliver needed treatments reliably and rapidly. Our objective was to use a human simulation training educational environment to develop multidisciplinary team skills and improve medical emergency team (MET) performance. We report findings of a crisis team training course that is focused on organization.

SETTING

Large center for human simulation training at a university affiliated tertiary care hospital.

PARTICIPANTS

Ten courses were delivered and 138 clinically experienced individuals were trained (69 critical care nurses, 48 physicians, and 21 respiratory therapists). All participants were ACLS trained and experienced in responding to cardiac arrest situations. COURSE DESIGN: Each course had four components: (1) a web based presentation and pretest before the course; (2) a brief reinforcing didactic session on the day of the course; (3) three of five different simulated scenarios; each followed by (4) debriefing and analysis with the team. Three of five simulator scenarios were used; scenario selection and order was random. Trainees did not repeat any scenario or role during the training. Participants were video recorded to assist debriefing. Debriefing focused on reinforcing organizational aspects of team performance: assuming designated roles independently, completing goals (tasks) assigned to each role, and directed communication. MEASURES FOR IMPROVEMENT: Participants graded their performance of specific organizational and treatment tasks within specified time intervals by consensus. Simulator "survival" depended on supporting oxygenation, ventilation, circulation within 60 seconds, and delivering the definitive treatment within 3 minutes.

EFFECTS OF CHANGE

Simulated survival (following predetermined criteria for death) increased from 0% to 89%. The initial team task completion rate was 10-45% and rose to 80-95% during the third session.

LESSONS LEARNT

Training multidisciplinary teams to organize using simulation technology is feasible. This preliminary report warrants more detailed inquiry.

Hot spots in dynamic (18)FET-PET delineate malignant tumor parts within suspected WHO grade II gliomas

Molecular imaging studies have recently found inter- and intratumoral heterogeneity in World Health Organization (WHO) grade II gliomas. A correlative analysis with tumor histology, however, is still lacking. For elucidation we conducted the current prospective study. Fifty-five adult patients with an MRI-based suspicion of a WHO grade II glioma were included. [F-18]Fluoroethyltyrosine ((18)FET) uptake kinetic studies were combined with frame-based stereotactic localization techniques and used as a guide for stepwise (1-mm steps) histopathological evaluation throughout the tumor space. In tumors with heterogeneous PET findings, the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status and expression of mutated protein isocitrate dehydrogenase variant R132H (IDH1) were determined inside and outside of hot spot volumes. Metabolic imaging revealed 3 subgroups: the homogeneous WHO grade II glioma group (30 patients), the homogeneous malignant glioma group (10 patients), and the heterogeneous group exhibiting both low- and high-grade characteristics at different sites (15 patients). Stepwise evaluation of 373 biopsy samples indicated a strong correlation with analyses of uptake kinetics (p < 0.0001). A homogeneous pattern of uptake kinetics was linked to homogeneous histopathological findings, whereas a heterogeneous pattern was associated with histopathological heterogeneity; hot spots exhibiting malignant glioma characteristics covered 4-44% of the entire tumor volumes. Both MGMT and IDH1 status were identical at different tumor sites and not influenced by heterogeneity. Maps of (18)FET uptake kinetics strongly correlated with histopathology in suspected grade II gliomas. Anaplastic foci can be accurately identified, and this finding has implications for prognostic evaluation and treatment planning.

Calcium balance and acid-base status of women as affected by increased protein intake and by sodium bicarbonate ingestion

Six women, aged 38 to 62 yr, participated in a 40-day metabolic study to investigate the effect of level of protein intake and of sodium bicarbonate ingestion on urinary calcium, net calcium balance, net renal acid excretion, and arterialized venous blood pH and bicarbonate ion concentration. The diet contained 44 g protein during the first 16 days and 102 g during the remaining 24 days. During the last 10 days of the study, 5.85 g of sodium bicarbonate was ingested concomitantly with the higher protein intake. Calcium, phosphorus, and magnesium intakes were held constant at 500, 900, and 300 mg, respectively. The increase in protein intake significantly increased urinary calcium and net renal acid excretion and the mean net calcium balance became negative. The ingestion of sodium bicarbonate alkalinized the urine and reversed the increase in urinary calcium associated with the higher protein intake; the mean net calcium balance became positive. The arterialized venous blood pH and bicarbonate ion concentrations were not significantly affected by dietary treatments. The results suggest that the ingestion of a small amount of sodium bicarbonate may be an effective way to increase calcium retention in women with protein-induced hypercalciuria.

Nonviral gene delivery to the rat kidney with polyethylenimine

The aim of this study was to establish a nonviral method for gene delivery to the rat kidney. To this purpose, a panel of reagents was tested, including a monocationic lipid, DOTAP, a polycationic lipid, DOGS (or Transfectam), and three different forms of the cationic polymer polyethylenimine (PEI). A comparison among these compounds was performed in vivo, using luciferase as reporter gene. Complexes containing 10 microg of DNA were injected into the left renal artery of rats and allowed to remain in contact with the kidney for 10 min. Forty-eight hours later, luciferase expression levels in kidney extracts were measured. Kidneys injected with DNA complexed to the branched, 25-kD PEI polymer (PEI 25k) yielded activity levels significantly higher than control, sham-operated kidneys (2.7 x 10(4) vs. 5.2 x 10(3) RLU/kidney, respectively), whereas the other transfecting agents did not yield significant activity over controls. PEI 25k was therefore chosen for further optimization of transfection conditions. Dose-dependent luciferase expression was shown for 10, 50, and 100 microg of PEI-complexed DNA, reaching maximal levels of 2.4 x 10(5) RLU/kidney at 100 microg DNA. The optimal PEI nitrogen/DNA phosphate molar ratio was 10 equivalents. Luciferase activity peaked at 2 days, was still significantly higher than controls at 7 days, and was undetectable at 14 days post-injection. Using beta-galactosidase (beta-Gal) as a reporter, transgene expression was localized almost exclusively in proximal tubular cells.

Arousal and ventilatory responses during sleep in children with obstructive sleep apnea

Abnormal central regulation of upper airway muscles may contribute to the pathophysiology of the childhood obstructive sleep apnea syndrome (OSAS). We hypothesized that this was secondary to global abnormalities of ventilatory control during sleep. We therefore compared the response to chemical stimuli during sleep between prepubertal children with OSAS and controls. Patients with OSAS aroused at a higher PCO2 (58 +/- 2 vs. 60 +/- 5 Torr, P < 0.05); those with the highest apnea index had the highest arousal threshold (r = 0.52, P < 0.05). The hypercapnic arousal threshold decreased after treatment. For all subjects, hypoxia was a poor stimulus to arousal, whereas hypercapnia and, particularly, hypoxic hypercapnia were potent stimuli to arousal. Hypercapnia resulted in decreased airway obstruction in OSAS. Ventilatory responses were similar between patients with OSAS and controls; however, the sample size was small. We conclude that children with OSAS have slightly blunted arousal responses to hypercapnia. However, the overall ventilatory and arousal responses are normal in children with OSAS, indicating that a global deficit in respiratory drive is not a major factor in the etiology of childhood OSAS. Nevertheless, subtle abnormalities in ventilatory control may exist.

O-methylguanine-DNA methyltransferase (MGMT) mRNA expression predicts outcome in malignant glioma independent of MGMT promoter methylation

BACKGROUND

We analyzed prospectively whether MGMT (O(6)-methylguanine-DNA methyltransferase) mRNA expression gains prognostic/predictive impact independent of MGMT promoter methylation in malignant glioma patients undergoing radiotherapy with concomitant and adjuvant temozolomide or temozolomide alone. As DNA-methyltransferases (DNMTs) are the enzymes responsible for setting up and maintaining DNA methylation patterns in eukaryotic cells, we analyzed further, whether MGMT promoter methylation is associated with upregulation of DNMT expression.

METHODOLOGY/PRINCIPAL FINDINGS

ADULT PATIENTS WITH A HISTOLOGICALLY PROVEN MALIGNANT ASTROCYTOMA (GLIOBLASTOMA: N = 53, anaplastic astrocytoma: N = 10) were included. MGMT promoter methylation was determined by methylation-specific PCR (MSP) and sequencing analysis. Expression of MGMT and DNMTs mRNA were analysed by real-time qPCR. Prognostic factors were obtained from proportional hazards models. Correlation between MGMT mRNA expression and MGMT methylation status was validated using data from the Cancer Genome Atlas (TCGA) database (N = 229 glioblastomas). Low MGMT mRNA expression was strongly predictive for prolonged time to progression, treatment response, and length of survival in univariate and multivariate models (p<0.0001); the degree of MGMT mRNA expression was highly correlated with the MGMT promoter methylation status (p<0.0001); however, discordant findings were seen in 12 glioblastoma patients: Patients with methylated tumors with high MGMT mRNA expression (N = 6) did significantly worse than those with low transcriptional activity (p<0.01). Conversely, unmethylated tumors with low MGMT mRNA expression (N = 6) did better than their counterparts. A nearly identical frequency of concordant and discordant findings was obtained by analyzing the TCGA database (p<0.0001). Expression of DNMT1 and DNMT3b was strongly upregulated in tumor tissue, but not correlated with MGMT promoter methylation and MGMT mRNA expression.

CONCLUSIONS/SIGNIFICANCE

MGMT mRNA expression plays a direct role for mediating tumor sensitivity to alkylating agents. Discordant findings indicate methylation-independent pathways of MGMT expression regulation. DNMT1 and DNMT3b are likely to be involved in CGI methylation. However, their exact role yet has to be defined.

Perinatal lethality and multiple craniofacial malformations in MSX2 transgenic mice

MSX2 is a homeodomain transcription factor that has been implicated in craniofacial morphogenesis on the basis of its expression pattern during mouse development and the finding of a missense mutation (P148H) in humans affected with Boston-type craniosynostosis. We have generated transgenic mice carrying a 34 kb DNA fragment encompassing a human MSX2 gene encoding either wild-type or mutant (P148H) MSX2. Inheritance of either transgene resulted in perinatal lethality and multiple craniofacial malformations of varying severity, including mandibular hypoplasia, cleft secondary palate, exencephaly, and median facial cleft, which are among the severe craniofacial malformations observed in humans. Transgenic mice also manifested aplasia of the interparietal bone and decreased ossification of the hyoid. Transgene-induced malformations involved cranial neural-crest derivatives, were characterized by a deficiency of tissue, and were similar to malformations associated with embryonic exposure to ethanol or retinoic acid, teratogens that cause increased cell death. Together with previous observations implicating MSX2 expression in developmentally-programmed cell death, these results suggest that wild-type levels of MSX2 activity may establish a balance between survival and apoptosis of neural crest-derived cells required for proper craniofacial morphogenesis.

Trigeminal neuralgia due to neurovascular compression: high-spatial-resolution diffusion-tensor imaging reveals microstructural neural changes

PURPOSE

To preoperatively detect, by using diffusion-tensor imaging coregistered with anatomic magnetic resonance (MR) imaging, suspected microstructural tissue changes of the trigeminal nerves in patients with trigeminal neuralgia (TN) resulting from neurovascular compression.

MATERIALS AND METHODS

The study was approved by the institutional review board, and written informed consent was obtained from all patients. Twenty patients (mean age, 51.3 years) with TN and evidence of neurovascular contact were examined with use of a 3.0-T MR unit combined with an eight-channel head coil before undergoing surgical decompression. A single-shot diffusion-tensor echo-planar sequence was used along 15 different diffusion directions, with a b value of 1000 sec/mm(2) and a section thickness of 2 mm. For anatomic correlation, 0.6-mm isotropic three-dimensional fast imaging employing steady-state images were acquired for coregistration with the functional diffusion-tensor maps. After region of interest placement, mean fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were calculated for each nerve by using the paired-sample two-tailed t test (with P < .005 indicating significance) and compared with surgical findings.

RESULTS

FA was significantly lower (P = .004) on the trigeminal neuralgia-affected side (mean FA, 0.203) than on the contralateral side (mean FA, 0.239). ADCs were nearly identical between the normal and TN-affected nerve tissues.

CONCLUSION

These findings suggest that diffusion-tensor imaging enables the identification and quantification of anisotropic changes between normal nerve tissue and TN-affected trigeminal nerves. Coregistration of anatomic three-dimensional fast imaging employing steady-state imaging and diffusion-tensor imaging facilitates excellent delineation of the cisternal segments of the trigeminal nerves.

Postexposure effectiveness of varicella vaccine

OBJECTIVE

1) To describe the postexposure effectiveness of varicella vaccine in a homeless shelter; and 2) to demonstrate an effective public health intervention and its implications.

DESIGN

A prospective observational study.

SETTING

A women and children's shelter in Philadelphia with 2 cases of varicella before intervention.

OUTCOME MEASURES

Varicella in vaccinated and unvaccinated shelter residents; vaccine effectiveness for prevention of varicella when administered after exposure among children <13 years of age.

RESULTS

Sixty-seven shelter residents received varicella vaccine after exposure, including 42 children <13 years of age. One child who was unvaccinated developed varicella, but no vaccinated child developed typical disease. Vaccine effectiveness was 95.2% (95% CI, 81.6%-98.8%) for prevention of any disease and 100% for prevention of moderate or severe disease among the children <13 years of age.

CONCLUSION

When used within 36 hours after exposure to varicella in a setting where close contact occurred, varicella vaccine was highly effective in preventing further disease. This study provides support for the recent recommendation by the Advisory Committee on Immunization Practices to administer varicella vaccine after exposure: this practice should minimize the number of moderate or severe cases of disease and prevent prolonged outbreaks.

IDH1 mutations in grade II astrocytomas are associated with unfavorable progression-free survival and prolonged postrecurrence survival

BACKGROUND

The favorable prognostic impact of mutations in the IDH1 gene is well documented for malignant gliomas; its influence on World Health Organization (WHO) grade II astrocytomas, however, is still under debate.

METHODS

A previously published database of 127 predominantly surgically treated patients harboring WHO grade II astrocytomas was revisited. Patients were screened for TP53 mutations (sequencing analysis), IDH1 mutations (pyrosequencing), and MGMT promoter methylation (methylation-specific polymerase chain reaction and bisulfite sequencing). Endpoints were overall survival, progression-free survival (PFS), time to malignant transformation, and postrecurrence survival. Radiotherapy was usually withheld until tumor progression/malignant transformation occurred.

RESULTS

IDH1 mutations, TP53 mutations, and methylated MGMT promoters were seen in 78.1%, 51.2%, and 80.0% of the analyzed tumors, respectively. IDH1 mutations, which were significantly associated with TP53 mutations and/or MGMT promoter methylation (P < .001), resulted in shortened PFS (median, 47 vs 84 months; P = .004); postrecurrence survival, however, was significantly increased in those patients undergoing malignant transformation (median, 49 vs 13.5 months; P = .006). Overall survival was not affected by IDH1. A similar pattern of influence was seen for MGMT promoter methylation. Methylated tumors did significantly worse (better) in terms of PFS (postrecurrence survival); a low number of unmethylated tumors, however, limited the power of this analysis. Conversely, TP53 mutations were stringently associated with a worse prognosis throughout the course of the disease.

CONCLUSIONS

IDH1 mutations are associated with a Janus headlike phenomenon; unfavorable prognostic influence on PFS turns into favorable impact on postrecurrence survival. A similar pattern of influence might exist for MGMT methylation.

Effect of angiotensin-converting enzyme inhibition on growth factor mRNA in chronic renal allograft rejection in the rat

BACKGROUND

Despite considerable progress in immunosuppression, the incidence of chronic renal allograft rejection has not decreased. Recent studies have revealed that angiotensin-converting enzyme (ACE) inhibition ameliorates graft arteriosclerosis, glomerulosclerosis, and tubular atrophy. Moreover, it decreases systemic and glomerular capillary hydrostatic pressure in a rat kidney allograft model. We evaluated the effects of the ACE inhibitor enalapril on cytokine and growth factor expression in chronically rejecting rat kidney allografts.

METHODS

Kidneys of Fisher (F344) rats were orthotopically transplanted into Lewis (Lew) rats. To prevent acute rejection, cyclosporine A (1.5 mg/kg/day) was given to all recipients during the first 10 days after transplantation. Enalapril (60 mg/L) or vehicle was added to the drinking water 10 days after transplantation. Animals were harvested 20 weeks after transplantation for histologic and immunohistologic studies, as well as for evaluation of cytokine and growth factor mRNA by semiquantitative polymerase chain reaction.

RESULTS

Controls developed severe signs of chronic rejection, such as glomerular and vascular lesions, associated with a large number of infiltrating leukocytes. Enalapril-treated animals developed less proteinuria and other signs of chronic rejection. The mRNA levels of transforming growth factor-beta 1 (TGF-beta 1), platelet-derived growth factor A and B chain (PDGF A and B), insulin-like growth factor-I (IGF-I), interleukin-1 (IL-1), and monocyte chemoattractant protein-1 (MCP-1) were significantly reduced in the enalapril group and were most pronounced for IL-1 and PDGF A. In addition, we found an increased level of renal angiotensinogen mRNA after treatment with enalapril.

CONCLUSIONS

Treatment with enalapril attenuated the development of proteinuria, ameliorated morphological damage, decreased leukocyte infiltration, and prevented a rise in renal mRNA levels of growth factors and cytokines in kidney grafts in a rat model of chronic renal allograft rejection.

Residue-specific bioincorporation of non-natural, biologically active amino acids into proteins as possible drug carriers: structure and stability of the per-thiaproline mutant of annexin V

Residue-specific bioincorporation of 1,3-thiazolidine-4-carboxylic acid [thiaproline, Pro(S)], a non-natural amino acid analog of proline, into human recombinant annexin V was achieved with a proline-auxotrophic Escherichia coli strain by fermentation procedures in minimal medium. Quantitative replacement of proline with thiaproline was confirmed by mass-spectrometric, amino acid, and x-ray crystallographic analyses. The wild-type protein and its per-Pro(S) mutant were found to crystallize isomorphously and to show identical three-dimensional structures in crystals. In solution the dichroic properties of the wild-type and per-Pro(S) protein confirmed nearly identical overall folds. From thermal denaturation experiments, however, a reduced Tm (-4.5 K) value was determined whereas the van't Hoff enthalpy and entropy were not significantly affected. Therefore, protein mutants containing bioactive amino acid analogs like thiaproline at multiple sites would be expected to fully retain their functional properties, including immunogenicity, and thus could serve as promising vehicles for targeted drug delivery.

Mother-daughter pairs: spinal and femoral bone densities and dietary intakes

Bone mineral density (BMD) of the lumbar spine (L1-L4) and femur (femoral neck, Ward's triangle, and trochanter) was measured in 37 healthy, white mother-daughter pairs by dual-photon absorptiometry. Mothers and daughters were aged 52 +/- 7 and 25 +/- 4 y (mean +/- SD), respectively. Three-day dietary intakes were evaluated. Significant correlations between mother-daughter pairs for BMD of all lumbar and femoral areas [except for L2 (r = 0.26, P = 0.054)] indicated familial resemblances in bone mineralization. Total calcium intake was significantly correlated with three BMD values for the daughters (L2, femoral neck, and trochanter) but not for the mothers. When mothers were classified as pre- (n = 20) or postmenopausal (n = 17), correlation coefficients for BMD were higher for premenopausal mothers and their daughters and lower for postmenopausal mothers and their daughters, except for the trochanter. The results suggest that the nature of inheritance of bone mass of women may have at least two components, one influencing the level of peak bone mass and one related to bone loss at menopause.

Developmental changes in response to subatmospheric pressure loading of the upper airway

Children snore less than adults and have fewer obstructive apneas, suggesting a less collapsible upper airway. We therefore hypothesized that the compensatory upper airway responses to subatmospheric pressure loading decrease with age because of changes in upper airway structure and ventilatory drive. We measured upper airway upstream pressure-flow relationships during sleep in 20 nonsnoring, nonobese children and adults. Measurements were made by correlating maximal inspiratory airflow with the level of nasal pressure applied via a mask. The slope of the upstream pressure-flow curve (S(PF)) was used to characterize upper airway function. We found that S(PF) was flatter in children than in adults (8 +/- 5 vs. 30 +/- 18 ml x s(-1). cmH(2)O(-1), P < 0.002) and that S(PF) correlated with age (r = 0.62, P < 0.01) and body mass index (r = 0. 63, P < 0.01). The occlusion pressure in 100 ms during sleep was measured in six children and two adults; it correlated inversely with S(PF) (r = -0.80, P < 0.02). We conclude that the upper airway compensatory responses to subatmospheric pressure loading decrease with age. This is associated with increased body mass index, even in nonsnoring, nonobese subjects. Ventilatory drive during sleep plays a role in modulating upper airway responses.

Oxygen supply and uptake in the liver and the intestine

The oxygen supply to the liver was found to be dependent on the total blood flow only and not on the ratio of arterial to portal contribution. The mean value of O2-uptake in the liver, related to a blood flow of 110 ml/min - 100 g liver, amounted to 6.08 +/- 0.2 ml O2/min - 100 g liver (mean +/- S.E.M.). O2-uptake of the intestine was found to be 1.95 +/- 0.13 ml O2/min - 100 g tissue, related to a normal blood flow of 50 ml/min - 100 g tissue. With low oxygen supply O2 extraction in the liver reaches values of 97%, whereas the intestinal extraction does not surpass 75%. A rise in oxygen supply surmounting normal values does not increase the O2-consumption. Contrary to the intestinal circulation the liver showed no postocclusive vasodilatation. The oxygen debt was payed back by a greater extraction. The portal oxygen supply to the liver can markedly increase due to intestinal metabolic hyperemia. High O2-extraction capacity, rather than vasodilatation, is the main mechanism for matching hepatic oxygen supply with requirements. The hepatic venous blood may leave the liver with an extremely low O2-content.

Response to inspiratory resistive loading during sleep in normal children and children with obstructive apnea

The response to inspiratory resistance loading (IRL) of the upper airway during sleep in children is not known. We, therefore, evaluated the arousal responses to IRL during sleep in children with the obstructive sleep apnea syndrome (OSAS) compared with controls. Children with OSAS aroused at a higher load than did controls (23 +/- 8 vs. 15 +/- 7 cmH(2)O. l(-1). s; P < 0.05). Patients with OSAS had higher arousal thresholds during rapid eye movement (REM) vs. non-REM sleep (P < 0.001), whereas normal subjects had lower arousal thresholds during REM (P < 0.005). Ventilatory responses to IRL were evaluated in the controls. There was a marked decrease in tidal volume both immediately (56 +/- 17% of baseline at an IRL of 15 cmH(2)O. l(-1). min; P < 0.001) and after 3 min of IRL (67 +/- 23%, P < 0.005). The duty cycle increased. We conclude that children with OSAS have impaired arousal responses to IRL. Despite compensatory changes in respiratory timing, normal children have a decrease in minute ventilation in response to IRL during sleep. However, arousal occurs before gas-exchange abnormalities.

Effects of potential blood substitutes (perfluorochemicals) on rat liver and spleen

The effect of an emulsion of perfluorochemicals (PFC) (7 parts perfluorodecalin and 3 parts perfluorotripropylamine, 4.4 g PFC/kg body weight) on organ function was determined. Whereas maximal storage of PFC was reached in the spleen as early as 12 h after PFC administration, the liver attained a maximal PFC content only after 2 days. The increase in weight also differed: a maximum occurred in the spleen on the 4th day, in the liver on the 8th day. Indocyanine green (ICG) clearance showed a small decrease, statistically significant after 12 and 24 h. Colloidal carbon clearance, used as a measure of the function of the reticuloendothelial system (RES) decreased instantly after PFC to less than half the control value; after full recovery a second decrease was seen which lasted till the 4th day after PFC. Pretreatment with C 48/80 or with increasing doses of E. coli endotoxin could largely obviate the depressive effect of PFC-loading on carbon clearance. Serum transaminases increased to about twice the control levels but were normal by the 2nd day, and thereafter. Alkaline phosphatase showed a 2.5 fold increase but returned to control level after the 2nd day. It is concluded that while a severe disturbance of liver function did not occur, the reduction in the capacity of the RES can become a serious factor in the defence against a simultaneously appearing infection if not compensated by activating the RES.

19F-MRI in vivo determination of the partial oxygen pressure in perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity and different tissues

Semipermeable hydrogels formed with a biocompatible alginate solution and Ba(2+) ions protect encapsulated cells and tissues from a foreign immune system. For the viability and metabolic activity of the encapsulated materials, a sufficient oxygen supply inside the capsules is necessary. Quantitative (19)F-MRI was performed on perfluorocarbon-loaded alginate capsules implanted into the peritoneal cavity, the musculus quadriceps femoris, and beneath the kidney capsule of rats, in order to determine in vivo the partial oxygen pressure (pO(2)) inside the capsules at these implantation sites. The temporal behavior of the pO(2) values was observed for at least 3 months. The most stable values over time were observed in the kidney, where inter-rat pO(2) differences were considerable. In the muscle, the values were very high directly after implantation and decreased to nearly zero after 2 weeks. In the peritoneal cavity, values changed randomly over a wide range between different rats and over time. Magn Reson Med 42:1039-1047, 1999.

Susceptibility-weighted angiography (SWAN) of cerebral veins and arteries compared to TOF-MRA

PROBLEM

High resolution, non-contrast imaging of both cerebral veins and arteries by use of gradient echo T2 star weighted angiography (SWAN) is a new method for susceptibility-weighted imaging with short acquisition times. We assessed the potential of this sequence for the depiction of both cerebral veins and arteries.

METHODS

15 healthy volunteers were included in the study. MRI was performed on a 3T MR scanner using the following sequences: (1) a 3D multi-echo gradient echo T2 star weighted angiography (SWAN), (2) an arterial 3D TOF MR angiography and (3) a venous 2D TOF. With regard to the SWAN sequence, both MinIP and MIP images were reconstructed and systematically compared to MIP reconstructions of the artTOF and the venTOF. To suggest possible clinical implications of our findings, we additionally included two illustrative cases.

RESULTS

With regard to the visualization of the cerebral veins, the MinIP reconstructions of the SWAN sequence were considerably superior compared to the venTOF. Concerning the depiction of the main segments of the big cerebral arteries the value of the MIP reconstructions of the SWAN was comparable to that of the artTOF with limitations in the homogenity and in the depiction of smaller arteries.

CONCLUSIONS

SWAN allows for high-resolution visualization of both cerebral veins and arteries in one sequence without application of contrast agent and with significantly shortened scan time compared to the combined scan time of TOF-MRA and TOF-MRV. By use of either MinIP or MIP reconstructions, the arteries can be distinguished from the veins.

Bone mineral, serum calcium, and dietary intakes of mother/daughter pairs

Data on factors potentially responsible for familial differences in the incidence of postmenopausal osteoporosis were obtained for 26 mother/daughter pairs. The factors were: bone mineral content of the radius (BMC); bone mineral content to bone width ratio (BMC/W); serum ionized (Ca++), ultrafiltrable (UF-Ca) and total calcium (T-Ca), ultrafiltrable and total magnesium, and 25-hydroxyvitamin D; and 7-day dietary intakes of selected nutrients. The BMC, BMC/W, and serum calcium fractions of the mothers were significantly correlated with those of the daughters. Although the BMC of the mothers was related to their caloric intakes, the interrelations between BMC and other variables of each group were not significant. Estimates of heritability, a measure of familial resemblance, were 0.724 for BMC; 0.570 for BMC/W; and 0.932, 0.916, and 0.668 for Ca++, UF-Ca, and T-Ca, respectively. Mothers with low BMC tended to have daughters with low BMC; there were also familial resemblances in serum calcium fractions.

Microstructural alterations in trigeminal neuralgia determined by diffusion tensor imaging are independent of symptom duration, severity, and type of neurovascular conflict

OBJECT

In this prospective study diffusion tensor imaging (DTI) was used to evaluate the influence of clinical and anatomical parameters on structural alterations within the fifth cranial nerve in patients with trigeminal neuralgia (TN) due to neurovascular compression.

METHODS

Overall, 81 patients (40 men and 41 women; mean age 60 ± 5 years) with typical TN were included who underwent microsurgical decompression. Preoperative 3.0-T high-resolution MRI and DTI were analyzed in a blinded fashion. The respective fractional anisotropy (FA) and apparent diffusion coefficient values were compared with the clinical, imaging, and intraoperative data. This study was approved by the institutional review board, and written informed consent was obtained from all patients.

RESULTS

DTI analyses revealed significantly lower FA values within the vulnerable zone of the affected trigeminal nerve compared with the contralateral side (p = 0.05). The DTI analyses also included 3 patients without clear evidence of neurovascular conflict on preoperative MRI. No differences were seen between arterial and venous compression. Lower FA values were found 5 months after symptom onset; however, no correlation was found with the duration of symptoms or severity of compression.

CONCLUSIONS

DTI analysis allows the quantification of structural alterations, even in those patients without any discernible neurovascular contact on MRI. Moreover, our findings support the hypothesis that both the arteries and veins can cause structural alterations that lead to TN. These aspects can be useful for making treatment decisions.

Increased lipid peroxide levels and myeloperoxidase activity in the vitreous of patients suffering from proliferative diabetic retinopathy

Lipid peroxide (LPO) levels, as determined by high-performance liquid chromatography (HPLC) and by the thiobarbituric acid (TBA) method, and myeloperoxidase (MPO) activity in vitreous of patients vitrectomized because of proliferative diabetic retinopathy were compared with LPO levels and MPO activity in vitreous of patients with no vitreoretinal proliferation. Both LPO levels and MPO activity were significantly elevated in the vitreous of patients with fibrovascular vitreoretinal proliferations secondary to diabetes. The TBA method produced higher values for LPO levels than did the HPLC method. The correlation between the two methods was 0.94. Our results suggest that both oxygen-free radicals and inflammation-related reactions can participate in the pathogenesis of diabetic retinopathy.

Juvenile dermatomyositis: the association of the TNF alpha-308A allele and disease chronicity

Little is known concerning factors associated with the outcome of juvenile dermatomyositis (JDM), which can be variable and lethal. Previous work has documented that the association of DQA1*0501 with JDM is higher than in control groups and that the first symptoms (rash and weakness) of JDM appear to follow evidence of an infectious process--most frequently upper respiratory in nature. Preliminary data show that a long period of symptoms being left untreated before starting therapy and the TNF alpha-308A allele are associated with prolonged JDM symptoms requiring > or = 36 months of immunosuppressive therapy. A short duration of untreated disease is associated with a relative increase in CD8(+) T cells and CD56(+) natural killer (NK) cells in the untreated JDM muscle biopsy compared with a longer duration of untreated disease. The TNF alpha-308A allele is overrepresented in white children with JDM. In addition, it is associated with pathologic calcifications, increased production of TNF alpha by peripheral blood mononuclear cells in vitro and JDM muscle fibers in vivo, and occlusion of capillaries, which may be mediated in part by elevated circulating levels of thrombospondin-1, a potent anti-angiogenic factor. We speculate that DQA1*0501 is associated with JDM susceptibility to an infectious process, eliciting and activating NK cells early in the disease course. We conclude that the TNF alpha-308A allele indicates directly (or is a surrogate marker of) children with JDM who produce higher concentrations of TNF alpha in response to this undefined inflammatory stimulus, as well as increased concentrations of TSP-1 with resultant small vessel occlusion, contributing to subsequent disease chronicity.

Hemodynamic consequences of severe pancreatitis

Fifteen patients with severe pancreatitis underwent cardiovascular monitoring in an intensive care unit. The principal findings were a high cardiac index and a decrease in systemic vascular resistance. A significant negative correlation was found to exist between these two parameters (p less than 0.001). Severe pancreatitis apparently results in hemodynamic changes similar to those observed in sepsis. The mechanisms responsible for these observations are not known, although circulating vasoactive compounds resulting from pancreatic necrosis remain a strong possibility. Despite demonstrating a significant decrease in left ventricular stroke work index and an abnormal elevation in pulmonary capillary wedge pressure, the existence of a myocardial depressant factor could not be conclusively proved from these data.