Cortical aging - new insights with multiparametric quantitative MRI

Understanding the microstructural changes related to physiological aging of the cerebral cortex is pivotal to differentiate healthy aging from neurodegenerative processes. The aim of this study was to investigate the age-related global changes of cortical microstructure and regional patterns using multiparametric quantitative MRI (qMRI) in healthy subjects with a wide age range. 40 healthy participants (age range: 2^nd to 8^th decade) underwent high-resolution qMRI including T1, PD as well as T2, T2* and T2′ mapping at 3 Tesla. Cortical reconstruction was performed with the FreeSurfer toolbox, followed by tests for correlations between qMRI parameters and age. Cortical T1 values were negatively correlated with age (p=0.007) and there was a widespread age-related decrease of cortical T1 involving the frontal and the parietotemporal cortex, while T2 was correlated positively with age, both in frontoparietal areas and globally (p=0.004). Cortical T2′ values showed the most widespread associations across the cortex and strongest correlation with age (r= -0.724, p=0.0001). PD and T2* did not correlate with age. Multiparametric qMRI allows to characterize cortical aging, unveiling parameter-specific patterns. Quantitative T2′ mapping seems to be a promising imaging biomarker of cortical age-related changes, suggesting that global cortical iron deposition is a prominent process in healthy aging.

Distribution of Cortical Diffusion Tensor Imaging Changes in Multiple Sclerosis

Purpose

Diffuse cortical damage in relapsing–remitting multiple sclerosis (RRMS) is clinically relevant but cannot be directly assessed with conventional MRI. In this study, it was aimed to use diffusion tensor imaging (DTI) techniques with optimized intrinsic eddy current compensation to quantify and characterize cortical mean diffusivity (MD) and fractional anisotropy (FA) changes in RRMS and to analyze the distribution of these changes across the cortex.

Materials and Methods

Three-Tesla MRI acquisition, mapping of the MD providing information about the integrity of microstructural barriers and of the FA reflecting axonal density and surface-based analysis with Freesurfer were performed for 24 RRMS patients and 25 control subjects.

Results

Across the whole cortex, MD was increased in patients (p < 0.001), while surface-based analysis revealed focal cortical FA decreases. MD and FA changes were distributed inhomogeneously across the cortex, the MD increase being more widespread than the FA decrease. Cortical MD correlated with the Expanded Disability Status Scale (EDSS, r = 0.38, p = 0.03).

Conclusion

Damage of microstructural barriers occurs inhomogeneously across the cortex in RRMS and might be spatially more widespread than axonal degeneration. The results and, in particular, the correlation with the clinical status indicate that DTI might be a promising technique for the monitoring of cortical damage under treatment in larger clinical studies.

L'hygiène hospitalière et le conseil en antibiothérapie : un duo opérationnel face au problème de la diffusion des bactéries multirésistantes aux antibiotiques

OBJECTIVES

The authors had for aim to show that preventing the diffusion of multidrug-resistant organism (MRO) is possible thanks to the coordination of recommended preventive actions and the implementation of a sensible anti-infective prescription policy. They also wanted to highlight the role played by the nursing care staff in enforcing recommendations.

METHOD

We compared the results of two health care facilities having both implemented the same strategy aimed at preventing cross-transmission and prescribing anti-infective drugs.

RESULTS

Audits reported a very variable enforcement of recommendations. The results obtained from microbiological monitoring confirmed the essential impact of protocol enactment by every team, on the control of MRO diffusion. The antibiotherapy specialist has a key role in the suggested strategy, allowing a significant decrease in the number of anti-infective prescriptions and a more rational use.

CONCLUSION

The collaboration of a hygiene specialist with an antibiotherapy specialist has proved operational in the fight against MRO diffusion, as long as the competences of both specialists are acknowledged and their cross-disciplinary activities accepted. For the entire staff, enacting a corporate culture is a crucial asset.

Medical learning curves and the Kantian ideal

A hitherto unexamined problem for the "Kantian ideal" that one should always treat patients as ends in themselves, and never only as a means to other ends, is explored in this paper. The problem consists of a prima facie conflict between this Kantian ideal and the reality of medical practice. This conflict arises because, at least presently, medical practitioners can only acquire certain skills and abilities by practising on live, human patients, and given the inevitability and ubiquity of learning curves, this learning requires some patients to be treated only as a means to this end. A number of ways of attempting to establish the compatibility of the Kantian Ideal with the reality of medical practice are considered. Each attempt is found to be unsuccessful. Accordingly, until a way is found to reconcile them, we conclude that the Kantian ideal is inconsistent with the reality of medical practice.

Telemedicine: application of telepathology-remote microscopy for intraoperative diagnoses on frozen sections

Due to the time delay, intraoperative consultations result in an extension of operation times, leading to prolonged anesthesia and idle time during surgery. Using a remote controlled microscope for telepathology, transfer times between hospital and pathologist can be eliminated and pathological expertise obtained independently of the geographic location of the hospital. In cooperation with a community hospital located 100 km apart from the Institute of Pathology of the Justus Liebig University Giessen, telepathological intraoperative consultations have been performed since 1999. After preparation and staining of the cryosection in the hospital, the slide was examined in our institute using a remote-controlled microscope (Leica DMRXA) and a special telepathological software (Leica TPS1). Data were transferred via two ISDN connections in parallel. The telepathology system contains an additional macroscopic examination equipment. Up to now more than 40 telepathological consultations have been done. Time required for the microscopic diagnosis ranged between 4 and 25 minutes. The amount of time saved, compared to the transfer to the next available pathologist, was approximately 45 minutes. In our experience, telepathological diagnoses were fully in accordance with conventional diagnoses routinely performed afterwards. The application of telepathology can lead to a significant shortening of surgery time if a pathologist is locally not available. In the study presented, no diagnostic errors occurred. The additional application of a macroscopic equipment allows inspection and interactive guidance for sampling, thus preventing sampling errors.

Behavioral sequelae of perinatal insults and early family adversity at 8 years of age

OBJECTIVE

This prospective longitudinal study investigated the simultaneous impact of early biological and psychosocial risk factors on behavioral outcome at school age.

METHOD

A cohort of 362 children born between 1986 and 1988 with different biological (perinatal insults) and psychosocial risk factors (family adversity) was followed from birth to school age. When their children were aged 8 years, parents of 89.0% of the initial sample completed the Child Behavior Checklist (CBCL).

RESULTS

More externalizing as well as internalizing problems were found in children born into adverse family backgrounds, whereas no differences at broad-band syndrome level were apparent between groups with varying obstetric complications. Children with family risk factors had higher scores on 5 of the 8 CBCL scales (including attention, delinquent, and aggressive problems), whereas children with perinatal risk factors had more social and attention problems than children in the nonrisk groups. With one exception, no interactions between risk factors emerged, indicating that perinatal and family risk factors contributed independently to outcome. The differences between risk groups applied irrespective of gender.

CONCLUSIONS

The adverse impact of family adversity clearly outweighed the influence of obstetric complications in determining behavioral adjustment at school age.

Immunocytological determination of lymphocytes and monocytes/macrophages in urinary sediments of renal allograft recipients

BACKGROUND

Urinary studies using Papanicolaou staining following kidney transplantation led to the conjecture that acute allograft rejection might be accompanied by an increased lymphocyturia. However, it is difficult to distinguish lymphoid cells from other urinary cells using conventional stains.

METHODS

Staining of urinary lymphocytes using FITC-labelled antibodies is complicated by a high unspecific fluorescence that limits the evaluation. Therefore, we developed a method to stain urinary lymphocytes using enzyme-linked antibodies. The cells were cytocentrifuged onto microscope slides and were fixed.

RESULTS

By means of a combined evaluation of Papanicolaou and immunocytochemical staining, CD3-positive pan T cells, CD4-positive T-helper cells, CD8-positive cytotoxic/suppressor cells, and CD14-positive monocytes/macrophages of urinary sediments were determined in 41 kidney graft recipients following renal transplantation. During periods of normal graft function, neither positive lymphocytes nor positive monocytes/macrophages were found in the urinary sediments. However, in the course of acute allograft rejection a significant increase in positive lymphocytes and positive monocytes/macrophages could be observed. Interestingly, in cases of acute allograft rejection the distribution of urinary lymphocytes and monocytes was comparable to the distribution of infiltrating immunocompetent cells in renal allograft biopsies.

CONCLUSION

The present study demonstrates that immunocytochemical staining via enzyme-conjugated antibodies is a reliable method to visualize T lymphocytes and monocytes/macrophages in the urinary sediment, and that this technique may be of special diagnostic value in the diagnosis of acute allograft rejection.

Soluble CD-4 and CD-8 as markers of immunological activation in renal transplant recipients

BACKGROUND

T lymphocytes are activated following kidney transplantation in cases of acute graft rejection and viral infections. In plasma, elevated levels of T-cell markers can be measured in soluble form. The reason for this shedding is still not entirely understood.

METHODS

Plasma concentrations of soluble CD-4 and CD-8 (sCD-4, sCD-8) were determined in 78 patients following kidney transplantation by commercially available enzyme-linked immunosorbent assay (ELISA) test kits.

RESULTS

The concentrations of both soluble T-cell markers increased significantly in the course of acute allograft rejections and cytomegalovirus (CMV) infections. Frequently, the parameters increased shortly before clinical diagnosis and decreased under successful therapy. Additionally, sCD-8 showed significant higher plasma concentrations in cases of CMV infection as compared with acute allograft rejections. Accordingly, the sCD-4/sCD-8 ratio increased in cases of acute allograft rejection and decreased during CMV infections. Cyclosporin A nephrotoxicity caused no significant changes in the sCD-4 and sCD-8 levels in plasma.

CONCLUSION

The present study demonstrates that sCD-4 and sCD-8 are markers of immunological activation and may enable a further differentiation of T-cell activation if serial measurements are performed. However, further prospective investigations are necessary to elucidate the diagnostic potential of sCD-4 and sCD-8 for monitoring acute rejection and viral infection in kidney graft recipients.

A patient dose survey for femoral arteriogram diagnostic radiographic examinations using a dose-area product meter

We present a method for dealing with a complex radiographic procedure (which involves multiple radiographs and fluoroscopy) in an attempt to provide a simple way of calculating effective dose from which a general risk factor can be determined. A useful index of harm can be obtained by recording the number of radiographs in each region, and the fluoroscopy time, from which the effective dose may be easily calculated. A patient dose survey was carried out using a PTW diamentor for femoral arteriogram procedures in a large teaching hospital. The procedure involves fluoroscopy to the pelvic region to locate a guide wire and catheter, followed by a series of radiographs extending from the pelvic area to the feet to form a collage image of the entire arterial system. Radiographs are taken whilst a bolus of contrast media is injected into the arterial system. These measurements extend a continuing survey of doses for common diagnostic radiographic examinations which have previously included the simple examinations of lumbar spine, abdomen and pelvis.

A patient dose survey for three common diagnostic radiographic examinations using a dose-area product meter

A patient dose survey was carried out for three common diagnostic radiographic examinations: lumbar spine, abdomen and pelvis. A dose-area product meter was used to determine the dose-area product delivered to the patient. The patient dose results reported in this study are lower than the results of the dose survey for United Kingdom hospitals which was recently published by the National Radiological Protection Board. Our data were also used to calculate the mean energy imparted and the mean effective dose from the examinations.

The pharmacokinetics of salicylate in the pregnant Wistar rat

Sodium salicylate, in a single dose of 50 mg/kg, was administered by iv injection to nonpregnant female and 20-day pregnant Wistar rats. Blood samples (for serum) and urine were collected and analyzed for salicylate, gentisic acid, salicyluric acid, and salicyl glucuronides by HPLC. Pregnant rats showed a significant decrease in body weight-normalized total clearance but no change in absolute total clearance of salicylate. On a body weight-adjusted basis there was a slight increase in the apparent volume of salicylate distribution in pregnancy but this increase becomes highly significant if expressed in absolute terms. The biological half-life of salicylate was significantly increased in late pregnancy. Serum protein binding of salicylate is decreased in pregnancy relative to nonpregnant females but in both groups binding shows a concentration dependence. The partial clearances of both salicyluric and gentisic acids were reduced by pregnancy in the rat whereas that of the salicyl glucuronides appeared unchanged. This latter result in intact pregnant animals contrasts with previously reported decreases in glucuronyltransferase activity in isolated liver preparations from pregnant rats.

Serum protein binding of drugs during and after pregnancy in humans

The serum protein binding of three weakly acidic drugs (salicylic acid, sulfisoxazole, and phenytoin), one week base (diazepam), and one steroid (dexamethasone) was determined in pregnant women at seven time periods during pregnancy and at two periods post partum, as well as in a group of nonpregnant women of childbearing age. The serum free fraction values (ratio of concentrations, free to total drug) of all drugs rose during pregnancy, primarily after 15 wk of gestation, and remained elevated for at least 1 to 5 days post partum. Pregnancy had the greatest effect on protein binding of sulfisoxazole, diazepam, and salicylic acid. The magnitude of this effect is such that quantitatively significant changes in the pharmacokinetic and pharmacodynamic characteristics of certain drugs may be expected to occur during pregnancy (in addition to possible changes caused by other pregnancy-related effects such as altered activity of drug-metabolizing enzyme systems). All drugs but dexamethasone exhibited significant negative correlations between free fraction values and serum albumin concentrations during pregnancy. The serum protein binding of salicylic acid, but not the other drugs tested, was more extensive in nonpregnant women who were not taking oral contraceptives than in those who were.

Antipyrine pharmacokinetics in the pregnant rat

Pronounced differences in pharmacokinetic parameters of antipyrine have been found in the 20-day pregnant hooded Wistar rat when compared with nonpregnant controls. Total body clearance falls significantly from 5.93 to 3.5 ml/min/kg in the pregnant rat whereas no significant increase in antipyrine volume of distribution occurs. These changes result in an increase in antipyrine half-life from 109 to 223 min in the pregnant rat. This study demonstrates that reduced hepatic mono-oxygenase capacity exists in the pregnant rat and that this can markedly affect drug clearance in there animals.

Serum protein binding of drugs during and after pregnancy in rats

The serum protein binding of salicylic acid (SA), sulfisoxazole (SUL), phenytoin (P), dexamethasone (D), diazepam (DI) and bilirubin (B) was determined in Long-Evans rats during pregnancy and after parturition. Serum free fraction (f) values were obtained by equilibrium dialysis (drugs) and by a reaction rate method (B). Concurrent control experiments were carried out on nonpregnant animals. Values of f were not significantly different from controls during the first 10 to 15 days of pregnancy. Pronounced increases in f of SA, SUL, P and D were observed on the 20th and 21st day of pregnancy; the f of DI was increased only on the 21st day and the f of B was not significantly changed at any time. The f values for SA, SUL and P returned almost to control levels 2 days after parturition (D, DI and B were not studied at that time). Additional studies with SUL, P and D on the 20th day of pregnancy showed that the increase in f occurred over a wide concentration range. Total serum protein and albumin concentrations were significantly decreased only on the 21st day of pregnancy. Pretreatment with activated charcoal decreased f of SA, SUL, P and D (the other compounds were not studied) in serum of 20-day pregnant (but not control) animals. The decreased protein binding of drugs in serum of pregnant rats appears to be due, at least in part, to accumulation of endogenous displacing agents.