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Biomedical subjects

A Frank

Publications and source records attributed to A Frank.

At least 19 recordsLinked to original sources
PubMed2006

Single-detector micro-electro-mechanical scanning grating spectrometer.

A compact, robust grating spectrometer based on an optimised micro-electro-mechanical grating mirror component has been developed, built, and characterised. The application of an oscillating reflection grating micro-mirror component as scanning dispersive element in a modified Czerny-Turner monochromator layout enables the design of compact grating spectrometers capable of acquiring full spectra using a single detector element. Designed for a wavelength range between 1200 and 1900 nm, the spectrometer features a spectral resolution of 10 nm with wavelength stability better than +/-0.5 nm. One-hundred scan spectra can be acquired in less than one second, or spectral changes can be monitored at time a resolution of less than 10 ms. In combination with a fibre-optic interface and a typical weight of less than 1 kg, this makes this novel type of fully portable micro-electro-mechanical near-IR scanning spectrometer an interesting alternative to existing spectrometers and opens a range of new applications, in particular the detection of major and minor components in the near-IR.

Journal Article↗
PubMed2006

The presence of B-cell nodules does not necessarily portend a less favorable outcome to therapy in patients with acute cellular rejection of a renal allograft.

The presence of B-cell nodules in kidney biopsies of patients undergoing acute renal allograft rejection has been reported to be associated with glucocorticoid resistance and a high risk of graft failure. In an attempt to corroborate this observation, biopsies of renal transplants that evidenced Banff grade I A acute rejection were examined for the presence of B- or T-cell nodules, the detection of which was correlated with the therapeutic response. Biopsies from 14 consecutive renal transplant recipients with a diagnosis of acute cellular rejection were examined for the presence of T (CD3-positive) or B (CD20-positive) cells by immunohistochemistry. All patients were biopsied because of a rise in serum creatinine. No biopsy showed evidence of acute humoral rejection. Immunofluorescence microscopy was negative for C4d deposition in peritubular capillaries. There were no neutrophils in the peritubular or glomerular capillaries. Five patients had T-cell nodules; four had B-cell nodules; three had both T- and B-cell nodules; two had no nodules. All biopsies contained CD3-positive cells in the tubules and in the interstitium. In all but one of the patients, episodes of acute rejection were treated with steroids (one received thymoglobulin). Furthermore two patients received mycophenolate mofetil and one, sirolimus. There were no significant differences among the groups in either the initial creatinine or the creatinine after therapy. The presence of B-cell nodules in renal allograft biopsies of patients experiencing acute cellular rejection did not portend a less favorable outcome.

Acute Disease↗
PubMed2006

c-Kit-positive mast cells in portal tracts cannot be used to distinguish acute cellular rejection from recurrent hepatitis C infection in liver allografts.

Cirrhosis secondary to chronic hepatitis C virus (HCV) is the most common indication for liver transplantation. Recurrence of HCV infection in the liver allograft occurs at a high rate. The differentiation of recurrent HCV infection from acute cellular rejection (ACR) represents a difficult challenge in transplantation pathology. The c-Kit receptor is a tyrosine kinase membrane protein encoded by the c-Kit proto-oncogene, which is expressed on mast cells and on hematopoietic stem and progenitor cells. Mast cells are important effector cells of a broad range of immune responses. Recently, c-Kit+ mast cells were shown to form part of the inflammatory infiltrate in acute liver allograft rejection. A strong relationship was found between c-Kit+ cell densities and increasingly severe rejection. The present study sought to determine whether the presence of c-Kit+ cells could be used to distinguish between ACR and recurrent HCV in liver allografts. Immunohistochemical staining for c-Kit was performed on 20 transplant biopsy specimens from 10 patients with mild to moderate ACR and 10 other patients with recurrent hepatitis C. The number of c-Kit+ cells per portal tract varied with the density of the overall inflammatory infiltrate. There was no significant difference between the number of c-Kit+ cells in the biopsy specimens that carried a diagnosis of ACR and those from patients who had been diagnosed as having recurrent HCV. It was concluded that immunohistochemical staining for the presence of c-Kit+ mast cells cannot be used to differentiate between ACR and recurrent HCV infection in liver allograft biopsy specimens.

Biopsy↗
PubMed2006

Can dynamic susceptibility contrast magnetic resonance imaging replace single-photon emission computed tomography in the diagnosis of patients with Alzheimer's disease? A pilot study.

PURPOSE: To compare single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer's disease (AD). MATERIAL AND METHODS: Twenty-four patients, eight with AD, 10 with MCI, and six controls were investigated with SPECT using 99mTc-hexamethylpropyleneamine oxime (HMPAO) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with gadobutrol. Three observers performed a visual interpretation of the SPECT and MR images using a four-point visual scale. RESULTS: SPECT was superior to DSC-MRI in differentiating normal from pathological. All three observers showed statistically significant results in discriminating between the control group, AD, and MCI by SPECT, with a P value of 0.0006, 0.04, and 0.01 for each observer. The statistical results were not significant for MR (P values 0.8, 0.1, and 0.2, respectively). CONCLUSION: DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer's disease. Several patient- and method-related improvements should be made before this method can be recommended for clinical practice.

Aged↗
PubMed2006

[Adult lateral meniscus].

Meniscal lesion does not mean meniscectomy and this is particularly true for the lateral meniscus. The reputation of mildness of the meniscectomy is usurped. The rate of joint space narrowing after lateral meniscectomy is of 40% at a follow-up of 13 years compared to 28% for the medial meniscus (symposium SFA 1996). Several arguments explain those results: biomechanical: the lateral meniscus contributes to the congruence; particularly the lateral meniscus is the zone where antero-posterior translational during knee flexion is 12 mm. The pejorative effects of lateral meniscectomy have conducted, more though to the medial meniscus, to the concept of meniscal economy. Lateral meniscectomy must be as partial as possible. Particularly, a discoid meniscus presenting a complete tear should be treated by a meniscoplasty in order to shape the meniscus in a more anatomic form than a total meniscectomy. Lateral meniscectomy is indicated in complex or horizontal cleavage, symptomatic, on stable knees. A particular case is the cyst of the lateral meniscus. It is a cystic subcutaneous formation, usual consequence of a horizontal cleaved meniscus of which the particularity is that it opens besides the articulation. The strategy must not consist in the isolated treatment of the cyst. This pathology should be addressed by an arthroscopic meniscectomy reaching the meniscosynovial junction at the level of the cyst. Meniscal repair must be proposed every time if possible. Criteria of reparability are better studied on MRI. Preoperatively MRI is the first choice radiological exam. Two essential indications can be held back: the vertical peripheral longitudinal lesion is on the non-vascularized area, and the horizontal cleaving of the junior athlete (if the cleaving remains purely intra meniscal). Meniscal repair is highly performed when the meniscal tear is associated to a rupture of the ACL (simultaneous reconstruction of the LCA). Postoperative outcome is different of that of a "simple" arthroscopic meniscectomy. The healing process being slow, it suits to protect the suture by a splint in the first month, and with an exclusion of sports with knee torsion during 6 months. Functional results (absence of secondary meniscectomy) and anatomical results (reality of the cicatrisation) are good in 77% of cases (symposium of the French Society of Arthroscopy 2003) at a follow-up of 55 months. Survivorship analysis indicates that majority of the failures occur within two years: this testifies a default of primary cicatrisation. At the studied follow-up, meniscal repair was efficient to protect the cartilage. Lateral meniscus results are better that medial meniscus one. Those data support indications: All suspicion of meniscal lesion must have an MRI preoperatively to confirm the lesion, to localize her and to search criteria of reparability; All vertical longitudinal peripheral lesions can and must be repaired especially in young patients and children; All horizontal cleaving of the junior athletes should be treated by open repair; surgical abstention must be proposed when the lesion is non symptomatic, or when lesion is limited and associated to an ACL tear (in that case isolated ACL reconstruction is proposed), or when clinical symptoms are minimal; Meniscectomy, always arthroscopic, is proposed for a symptomatic lesion in the avascular zone or for a deep horizontal cleavage or a complex tear; Tear of the discoid meniscus should be treated by meniscoplasty. A painful knee after lateral meniscectomy might be due to a too limited initial meniscectomy: an iterative meniscectomy may be indicated or lateral femorotibial arthritis, especially after subtotal or total meniscectomy. In this last case and after failure of usual medical treatment such as viscosupplementation surgery may be indicated. Osteotomy in order to unload the lateral femorotibial compartment gives a partial response as the shearing forces remain. This osteotomy is indicated only if the lower limb axis is normal or in valgus. Meniscal allograft is an option in young patients in grade I or II arthritis. Results are promising. Rene Verdonk's series show a survivorship analysis of 75% at 7 years. Early diagnosis of a postmeniscectomy syndrome before cartilaginous lesions occur is essential for an adapted treatment. In conclusion, lateral meniscectomy are less frequent than those of the medial meniscus but their prognosis is less favorable. They should be early diagnosed (MRI). Treatment options are various: abstention, meniscectomy, and repair. Painful post lateral meniscectomy syndrome may be treated by a new surgical option: meniscal allograft.

Cysts↗
PubMed2005

Deuteron transfer in N=Z nuclei.

Predictions are obtained for T=0 and T=1 deuteron-transfer intensities between self-conjugate N=Z nuclei on the basis of a simplified interacting boson model which considers bosons without orbital angular momentum but with full spin-isospin structure. These transfer predictions can be correlated with nuclear binding energies in specific regions of the mass table.

Journal Article↗
PubMed2005

Two-nucleon transfer reactions uphold supersymmetry in atomic nuclei.

The spectroscopic strengths of two-nucleon transfer reactions constitute a stringent test for two-nucleon correlations in the nuclear wave functions. A set of closed analytic expressions for ratios of spectroscopic factors is derived in the framework of nuclear supersymmetry. These ratios are parameter independent and provide a direct test of the wave functions. A comparison between the recently measured 198Hg(d-->,alpha)196Au reaction and the predictions from the nuclear quartet supersymmetry lends further support to the validity of supersymmetry in nuclear physics.

Journal Article↗
PubMed2005

Successful liver, kidney, and pancreas transplantation from a donor with cerebral emboli from a left atrial myxoma.

Although transmission and engraftment of donor-derived malignancies is rare in recipients of solid organ transplants, it is associated with unfavorable allograft and patient survival. Therefore, a recent history of malignancy is considered a contraindication to organ donation. Although atrial myxomas are benign cardiac tumors of stromal origin, they can lead to systemic embolization with ectopic myxoma formation. We report successful liver, kidney, and pancreas transplantation into 3 recipients from a donor with cerebral emboli from a left atrial myxoma. Eighteen months after transplantation, all 3 patients enjoy good allograft function and are free of donor-derived atrial myxoma. Although the duration of follow-up in this report is limited, we suggest that the presence of atrial myxoma should not be viewed as an absolute contraindication to organ recovery, particularly in view of the shortage of organ donors and the attendant morbidity and mortality for patients on waiting lists.

Adolescent↗
PubMed2004

Benefits of cognitive-motor intervention in MCI and mild to moderate Alzheimer disease.

OBJECTIVE: To evaluate the efficacy of a cognitive-motor program in patients with early Alzheimer disease (AD) who are treated with a cholinesterase inhibitor (ChEI). METHODS: Patients with mild cognitive impairment (MCI) (12), mild AD (48), and moderate AD (24) (Global Deterioration Scale stages 3, 4, and 5) were randomized to receive psychosocial support plus cognitive-motor intervention (experimental group) or psychosocial support alone (control group). Cognitive-motor intervention (CMI) consisted of a 1-year structured program of 103 sessions of cognitive exercises, plus social and psychomotor activities. The primary efficacy measure was the cognitive subscale of the AD Assessment Scale (ADAS-cog). Secondary efficacy measures were the Mini-Mental State Examination, the Functional Activities Questionnaire, and the Geriatric Depression Scale. Evaluations were conducted at 1, 3, 6, and 12 months by blinded evaluators. RESULTS: Patients in the CMI group maintained cognitive status at month 6, whereas patients in the control group had significantly declined at that time. Cognitive response was higher in the patients with fewer years of formal education. In addition, more patients in the experimental group maintained or improved their affective status at month 12 (experimental group, 75%; control group, 47%; p = 0.017). CONCLUSIONS: A long-term CMI in ChEI-treated early Alzheimer disease patients produced additional mood and cognitive benefits.

Aged↗
PubMed2004

An X-ray outburst from the rapidly accreting young star that illuminates McNeil's nebula.

Young, low-mass stars are luminous X-ray sources whose powerful X-ray flares may exert a profound influence over the process of planet formation. The origin of the X-ray emission is uncertain. Although many (or perhaps most) recently formed, low-mass stars emit X-rays as a consequence of solar-like coronal activity, it has also been suggested that X-ray emission may be a direct result of mass accretion onto the forming star. Here we report X-ray imaging spectroscopy observations which reveal a factor approximately 50 increase in the X-ray flux from a young star that is at present undergoing a spectacular optical/infrared outburst (this star illuminates McNeil's nebula). The outburst seems to be due to the sudden onset of a phase of rapid accretion. The coincidence of a surge in X-ray brightness with the optical/infrared eruption demonstrates that strongly enhanced high-energy emission from young stars can occur as a consequence of high accretion rates. We suggest that such accretion-enhanced X-ray emission from erupting young stars may be short-lived, because intense star-disk magnetospheric interactions are quenched rapidly by the subsequent flood of new material onto the star.

Journal Article↗
PubMed2003

Subacute meningoencephalitis in a subset of patients with AD after Abeta42 immunization.

BACKGROUND: AD is characterized by cerebral deposition of beta-amyloid plaques with amyloid beta-peptide (Abeta) 42 as the major peptide constituent, along with neurofibrillary tangles and neuronal loss. In transgenic mice, active immunization against Abeta42 removes these plaques and improves cognitive function. A Phase I study in AD patients demonstrated good safety and tolerability of multiple injections of aggregated Abeta42 (AN1792) with QS-21 as adjuvant. METHODS: Three hundred seventy-two patients with mild to moderate AD were randomized to receive IM injections of AN1792 or placebo (4:1) at baseline and at months 1, 3, 6, 9, and 12 in a multicenter Phase II safety, tolerability, and pilot efficacy study. Dosing was terminated after four early reports of meningoencephalitis, but follow-up continued. The study remains blinded, and further results will be reported after its termination. RESULTS: Symptoms and laboratory findings consistent with meningoencephalitis occurred in 18 of 298 (6%) patients treated with AN1792 compared with 0 of 74 on placebo (p = 0.020). Sixteen of the 18 had received two doses, one had received one dose, and one had received three doses of the study drug before symptoms occurred. The median latency from the first and last injections to symptoms was 75 and 40 days. No case occurred later than 6 months after the first immunization. Anti-Abeta42 antibody titers were not correlated with the occurrence or severity of symptoms or relapses. Twelve patients recovered to or close to baseline within weeks, whereas six remain with disabling cognitive or neurologic sequelae. All 18 patients remain alive to date (December 31, 2002), 6 months to >1 year after symptom onset. CONCLUSIONS: Postvaccination meningoencephalitis occurred without clear relation to serum anti-Abeta42 antibody titers. Potential mechanisms such as T-cell and microglial activation may be responsible and are under consideration to develop a safer anti-Abeta immunotherapy for AD.

Adrenal Cortex Hormones↗
PubMed2003

How atypical is atypical language dominance?

Atypical, right-hemisphere language dominance is poorly understood. It is often observed in patients with brain reorganization due to lesions early in life. It can also be encountered in seemingly normal individuals. We compared the patterns of neural language activation in 7 individuals with left- and 7 with right-hemisphere language dominance, none of whom had any evidence of brain lesions. We speculated that incongruencies in the activation patterns in atypical, right-hemisphere language dominance could indicate a reorganized neural language system after undetected early brain damage. Functional magnetic resonance imaging analysis of brain activation during phonetic word generation demonstrated (1). no increased activation in the subdominant hemisphere in right compared to left language dominance, (2). a similar variability in the pattern of activation in both groups, and (3). a mirror reverse pattern of activation in right- compared to left-hemisphere dominant subjects. These findings support the view that in individuals with an unrevealing medical history right-hemispheric dominance constitutes a natural rather than an abortive variant of language lateralization.

Adult↗
PubMed2002

APOE genotype in cerebrovascular disease and vascular dementia.

BACKGROUND: The fact that the allele epsilon 4 of the Apolipoprotein E (APOE) gene could act like a risk factor not only in late-onset familial and sporadic Alzheimer's disease (AD) but also in cerebrovascular disease (CVD) and vascular dementia (VaD) is still controversial. METHODS: In order to study if epsilon 4 allele is overrepresented not only in AD but also in CVD and VaD, APOE genotyping was undertaken in a series of 247 patients: 26 cases with VaD, 41 cases with CVD but without cognitive impairment (CVD-C), 83 cases with AD and 97 aged-matched "healthy controls" (HC). RESULTS: Percentages of subjects bearing one or two copies of the epsilon 4 allele was much higher in AD patients (54%) than in either CVD-C (29%) (p<0.05), VaD (15%) (p<0.001) or HC (13%) (p<0.001). CONCLUSIONS: These results strengthen the hypothesis that involves the APOE epsilon 4 allele as a predisposing factor for AD, but not for CVD or VaD.

Aged↗
PubMed2002

Contribution of APOE promoter polymorphisms to Alzheimer's disease risk.

OBJECTIVE: To determine whether the effects of APOE promoter polymorphisms on AD are independent of the APOE-epsilon4 allele. BACKGROUND: Recently, the -491 A-->T and -219 G-->T polymorphisms located in the APOE promoter have been suggested to be risk factors for AD. However, the effects of these polymorphisms have not always been reproduced in case-control studies, possibly because of the strong linkage disequilibrium existing at this locus or the characteristics of the populations studied. METHODS: Data collection was performed from six independent samples (1,732 patients with AD and 1,926 control subjects) genotyped for APOE exon 4 and the two APOE promoter polymorphisms. The risks associated with the APOE polymorphisms for developing AD were estimated using logistic regression procedures and calculation of odds ratios with 95% CI adjusted by age, sex, and collection center. Independence of the APOE promoter polymorphisms was tested by stratification for APOE-epsilon4 and tertile design was used for age stratification. RESULTS: The independence of the -491 AA genotype was observed in the whole sample whereas the independence of the -219 TT genotype was observed only in the oldest population. CONCLUSION: The -491 and -219 APOE promoter polymorphisms incur risk for AD in addition to risk associated with the APOE-epsilon4 allele, with age accentuating the effect of the -219 TT genotype. Because these polymorphisms appear to influence apoE levels, these results suggest that APOE expression is an important determinant of AD pathogenesis.

Aged↗
PubMed2002

[Influence of positioning on the quality of unilateral spinal anesthesia].

OBJECTIVE: Unilateral spinal anaesthesia ("hemi-spinal") is theoretically associated with the advantages of fewer cardiovascular effects and longer duration of action while offering high density motor block of the extremity affected. METHODS: In a prospective, randomised study 60 patients received 2 mls of 4 % hyperbaric mepivacaine intrathecally. Group I (n = 30) was returned into the supine position after 5 minutes in the lateral position, Group II (n = 30) was kept in the lateral position for 15 minutes. Spread and subsequently offset of sensory and motor block were assessed separately for each side at predetermined time intervals pre-, intra-, and postoperatively. RESULTS: Both groups were identical regarding their morphometric parameters. In Group I (5 minutes), the mean cephalad spread of sensory block of the initially dependent side was T6 after 15 mins and T4 after 25 mins. On the initially non-dependent side, the sensory block reached to T5 after 25 mins. In Group II (15 mins), the initial mean difference was equivalent to two segments (T7/T9). After 25 minutes there was no difference to the results in Group I. CONCLUSIONS: Unilateral spinal anaesthesia ("hemi-spinal") is an attractive concept, supposed to be associated with the above mentioned advantages and the additional benefit of a partially maintained sensation of one limb. The results demonstrated in this study seriously question this theoretical concept. The most likely reason for the lack of inter-lateral differences in sensory block is the high concentration of hyperbaric local anaesthetic in the cerebrospinal fluid on the dependent side, which, on turning the patient to the supine position, will transit to the previously non-dependent side subsequently leading to a significant block.

Anesthesia, Spinal↗
PubMed2002

Using geographical information systems for management of back-pain data.

In the medical world, statistical visualisation has largely been confined to the realm of relatively simple geographical applications. This remains the case, even though hospitals have been collecting spatial data relating to patients. In particular, hospitals have a wealth of back pain information, which includes pain drawings, usually detailing the spatial distribution and type of pain suffered by back-pain patients. Proposes several technological solutions, which permit data within back-pain datasets to be digitally linked to the pain drawings in order to provide methods of computer-based data management and analysis. In particular, proposes the use of geographical information systems (GIS), up till now a tool used mainly in the geographic and cartographic domains, to provide novel and powerful ways of visualising and managing back-pain data. A comparative evaluation of the proposed solutions shows that, although adding complexity and cost, the GIS-based solution is the one most appropriate for visualisation and analysis of back-pain datasets.

Back Pain↗
PubMed2001

Dynamos in asymptotic-giant-branch stars as the origin of magnetic fields shaping planetary nebulae.

Planetary nebulae are thought to be formed when a slow wind from the progenitor giant star is overtaken by a subsequent fast wind generated as the star enters its white dwarf stage. A shock forms near the boundary between the winds, creating the relatively dense shell characteristic of a planetary nebula. A spherically symmetric wind will produce a spherically symmetric shell, yet over half of known planetary nebulae are not spherical; rather, they are elliptical or bipolar in shape. A magnetic field could launch and collimate a bipolar outflow, but the origin of such a field has hitherto been unclear, and some previous work has even suggested that a field could not be generated. Here we show that an asymptotic-giant-branch (AGB) star can indeed generate a strong magnetic field, having as its origin a dynamo at the interface between the rapidly rotating core and the more slowly rotating envelope of the star. The fields are strong enough to shape the bipolar outflows that produce the observed bipolar planetary nebulae. Magnetic braking of the stellar core during this process may also explain the puzzlingly slow rotation of most white dwarf stars.

Journal Article↗