Dual-photon and dual-energy X-ray absorptiometry for the measurement of total-body bone mineral and soft tissue composition.
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Absorptiometry, Photon↗
Biomedical subjects
M Fischer
Publications and source records attributed to M Fischer.
Phantom studies in osteoporosis.
Differences in measurement results of bone densitometry are an obvious disadvantage of this method. The differences are mainly due to the calibration procedures for bone densitometry systems employed by the manufacturers, the software algorithms for defining the region of interest or edge detection, and the physiological inhomogeneity of body composition. Whereas intra-unit variation of reproducibility is acceptable, inter-unit variation may reach up to 20%. This paper discusses the problems of designing measurement phantoms and underlines the need for standardisation of phantoms for calibration, cross-calibration, and quality control in bone densitometry. A general phantom used for cross-calibration should handle all parameters influencing measurement of bone minerals to yielded dynamic reference values. One has to note that densitometry systems do not measure the absolute bone mineral content but a model-related equivalent of the calibration material.
Absorptiometry, Photon↗
Failure of the serological determination of HLA-B27 due to antigen masking in patients with ankylosing spondylitis.
In patients suffering from ankylosing spondylitis (AS) HLA-B27 determination by means of the microlymphocytotoxicity test (MLCT) sometimes gives equivocal or false-negative results even though it has been performed with meticulous care. These failures of the test did not arise when the isolated mononuclear cells (MNC) were incubated in lymphocyte culture medium at 37 degrees C under sterile conditions for 24 h. To objectify these observations two methods of HLA class I typing were implemented before and after incubation of the test MNC in culture medium: a bioluminescence method based on the loss of adenosine triphosphate (ATP) in lysed cells in a modification of the usual MLCT and a flow cytometric (FC) test using direct immunofluorescence with an anti-HLA-B27 monoclonal antibody (MAB). In this study 50 patients with AS and 12 healthy volunteers were typed by the usual MLCT according to the NIH standard method and with both of the quantitative methods. In most of the AS patients the discrimination between positive and negative typing results became more distinct after 24 h incubation in culture medium. In the entire group of AS patients tested three false-negative typing results were prevented by this method. Although the MAB against HLA-B27 is cross-reactive with HLA-B7 and HLA-B22, errors in the FC analysis could be avoided by calibration of the flow cytometer with standard calibration beads. Possible explanations for masking of the HLA-B27 in AS patients are discussed.
Adenosine Triphosphate↗
Expression and reconstitution of biologically active human acetylcholinesterase from Escherichia coli.
1. Authentic human acetylcholinesterase (AChE) was expressed in Escherichia coli under regulation of the constitutive deo promoter or the thermo-inducible lambda PL promoter. 2. To facilitate expression in the prokaryotic system, recombinant human AChE (rhAChE) cDNA was modified at the N terminus by oligonucleotide substitutions in order to replace some of the GC-rich regions by AT. These modifications did not alter the amino acid sequence but resulted in ample production of the protein. 3. rhAChE accumulated in the cells and reached a level of 10% of total bacterial proteins. A partially purified inactive recombinant protein was recovered from inclusion bodies. 4. Active rhAChE was obtained after solubilization, folding, and oxidation, although the recovery of the active enzyme was low. A 20- to 40-fold increase in enzymatically active rhAChE was achieved by replacing Cys580 by serine. 5. The recombinant enzyme analogue was indistinguishable from native AChE isolated from erythrocytes in terms of substrate specificity and inhibitor selectivity.
Acetylcholinesterase↗
The stability of dimensions of behavior in ADHD and normal children over an 8-year followup.
The present study reports on standardized behavioral ratings received by a large sample of hyperactive children meeting research diagnostic criteria (n = 108) and a community control sample of normal children (n = 61) who were followed prospectively over 8 years into adolescence. On some parent-report measures both groups declined in the severity of their behavior problems across time, while on other measures only the hyperactive group declined, but the hyperactives always remained more deviant than the controls at followup. The hyperactives and controls also differed on most teacher and self-report ratings at followup. The greatest degree of agreement between raters at adolescence was between parent and youth ratings. These results are consistent with previous research demonstrating more deviant scores for hyperactive children than controls on various rating scales at adolescent followup. They also are consistent with research showing significant longitudinal continuity of both internalizing and externalizing behavioral pathology.
Adolescent↗
The Extended Disability Status Scale (EDSS) as a predictor of impairments of functional activities of daily living in multiple sclerosis.
We investigated the relationship between the Kurtzke expanded disability status scale (EDSS) and an activities of daily living (ADL) scale that assesses disability across multiple functional domains based on self report of patients with multiple sclerosis (MS). Forty-three patients with definite MS responded on a 42-item ADL inventory and were also assigned an EDSS rating as part of their regular clinical examination. While a strong correlation was found between the EDSS and total ADL disability level, the ADL domain of 'Mobility' fully accounted for this relationship. The distribution of ADL scores as a function of EDSS level was curvilinear, as ADL variance was inconsistent across EDSS levels. Little ADL disability was evident when EDSS levels were below five. At higher EDSS levels, ADL variability increased substantially, making predictions regarding ADL level less exact.
Activities of Daily Living↗
Ischemic venous thrombosis caused by a distinct disturbance of the extrinsic clotting system.
Ischemic venous thrombosis that led to necrosis of four toes developed in an 81-year-old man. Despite the extensive thrombosis, results of blood clotting tests showed an extremely low prothrombin time (20%). Plasma mixing studies demonstrated an inhibitor that may have features in common with the lupus anticoagulant. Lupus anticoagulant also simulates hemorrhagic diathesis in vitro, whereas in vivo it is associated with thrombosis and thromboembolism. In contrast to the lupus anticoagulant, the inhibitor found in this patient was active within the extrinsic clotting system. Systemic steroids led to rapid clinical resolution paralleled by normalization of the prothrombin time and disappearance of the inhibitor.
Aged↗
[Correction of distal radial malunion by forward-sliding osteotomy. 3 case reports].
The "forward-sliding autograft" osteotomy is designed for the correction of malposition of the distal radius following distal radius fracture of which more than 70% (of 122 fractures) appear to unite with a dorsal tilt. The osteotomy technique described seems to be effective, maintaining identical length of both arms, and only needs local anesthesia. A local autologous graft is used instead of the iliac graft. Only minimal internal fixation material is required and removal of metal is not necessary. The dorsal approach is safe and free of nerve endings. The procedure is ideal for outpatient surgery and can be performed in a one day surgery center, ie on an outpatient basis. Osteopororis appears to have no effect on the results. However the technique is demanding and preoperative planning is mandatory. The surgeon should be familiar with the use of the external fixator in the case of secondary instability.
Adult↗
[Radio-carpal and medio-carpal arthroscopy in instability of the wrist].
Forty-one arthroscopies were performed on previously asymptomatic wrists following trauma. In about 25% of the wrists there was only one specific ligamentous lesion. In 75% however a combination of 2 or several distinct lesions was observed. These lesions, localised on the ulnar aspect of the mid-carpal joint, are more complex than those on the radio-carpal joint on the radial aspect of the carpus. These observations would tend to confirm our present day knowledge of wrist biomechanics but disagree with the currently proposed concepts of instability by several American authors. "Instability" seems to be inadequate to define complex lesions, more adequate would be the simple description of a "dysfunctional state" of the wrist complex. This statement must be related to the position of the carpal bones, which do not show any significant change despite the tears shown. The arthroscopy appears to range first in a series of diagnostic tools. However it concerns mainly the ligamentous layers facing the interior of the joint while lacking information about time elapsed since the actual trauma. We therefore state that arthroscopy may decrease but not exclude diagnostic failures. Type and risk of therapeutic decisions are also appreciated with increased accuracy. No doubt there still remain discrepancies when clinical, arthrographic and arthroscopic examination are compared, which indicates the complementary nature of the technics of investigation, especially in the light of the current state of the biomechanic sciences of the wrist.
Adolescent↗
[The influence of the new phosphodiesterase inhibitor enoximone in patients with an acute catecholamine-refractory heart insufficiency during open-heart surgery].
19 patients in whom cardiopulmonary bypass (cpb) was performed during different types of cardiac operations, developed myocardial failure which remained refractory to inotropic support with increasing doses of adrenaline, dopamine and dobutamine, so that it was impossible to discontinue cpb. After changing the therapeutic approach to a new regime consisting of adrenaline, dopamine and enoximone, low-output syndrome (LCOS) could be successfully reversed in 12 of the 19 patients. In the 7 remaining patients blood pressure dropped in a clinically relevant way under treatment with enoximone. 5 of these patients needed intraaortic balloon pumping (IABP) inspite of the application of enoximone, before cpb could be successfully discontinued. In three patients receiving enoximone, persisting ventricular tachyarrhythmia appeared under treatment, and disappeared after discontinuation of the drug. One patient needed IABP and left heart bypass by means of the centrifugal pump before cpb could be duly discontinued. One patient died intraoperatively due to untreatable right ventricular failure and inability to discontinue cpb. It is concluded that enoximone represents a useful drug in a significant number of patients developing heart failure refractory to inotropic support, on emerging from cpb during cardiac surgery.
Adult↗
Role of PrP in prion diseases.
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Animals↗
Isoflurane minimum alveolar concentration decreases during anesthesia and surgery.
BACKGROUND: It generally is assumed that the potency of inhalational anesthetics remains unchanged during the course of the administration of an anesthetic. Only one study has indicated a decrease of minimum alveolar concentration with time. In this study, an effect of the duration of anesthesia administration and surgery on the potency of isoflurane was investigated by determining MACtetanus (the minimum alveolar concentration that prevents movement in response to electrical tetanic stimulation in 50% of patients) before and after surgery. METHODS: Ten patients who underwent removal of a herniated intervertebral disc were anesthetized with isoflurane only. Reaction to a standardized electrical stimulation applied to the forearm was observed and was graded as movement or no-movement. The isoflurane concentration was increased in steps of 0.10 vol% if the patient moved and decreased in steps of 0.10 vol% if no reaction was seen, until a "movement/no-movement/movement" or "no-movement/movement/no-movement" pattern, respectively, was achieved. RESULTS: MACtetanus decreased in all patients from 1.28 +/- 0.22 vol% (mean +/- SD) before surgery to 1.04 +/- 0.22 vol% after surgery (P < 0.01). When the prestimulation arterial blood pressure or the maximal increase in blood pressure caused by stimulation at the individual MACtetanus before surgery were compared to the corresponding values at the individual MACtetanus after surgery, no significant difference could be found. The prestimulation heart rate and the maximal increase in heart rate were significantly lower after surgery, even though the end-tidal isoflurane concentration was 0.24 vol% lower at the individual MACtetanus after surgery. CONCLUSION: The authors conclude that MACtetanus decreases during the administration of anesthesia and the performance of surgery.
Adult↗
The adolescent outcome of hyperactive children: predictors of psychiatric, academic, social, and emotional adjustment.
OBJECTIVE: To investigate predictors of adolescent outcome in a large sample of hyperactive children. METHOD: 123 hyperactive children were followed prospectively over an 8-year period. Multiple linear and logistical regression equations were used to relate childhood predictor variables to adolescent academic, psychiatric, social, and emotional adjustment. RESULTS: Adolescent academic skills were related to childhood cognitive and academic competence while school conduct was predicted by other variables including early family stress. Duration of mental health treatment received often was negatively related to outcome, apparently serving as a marker variable for severity of disturbance in the child. Childhood impulsivity-hyperactivity and paternal antisocial acts were associated with later oppositional-defiant behaviors. Only child defiance and not hyperactivity predicted later arrests, however. Emotional problems in adolescence were predicted by more special education enrollment. Adolescent social competence was associated with parental personal competence, whereas maternal mental health status at outcome was related to variables unassociated with child adjustment. CONCLUSIONS: Various outcome domains had different sets of predictors; no single predictor cut across all domains. Although a limited amount of variance in outcome was explained, findings suggest that promoting family and parental competence as well as assessing and treating defiance and aggression very early may improve outcome.
Adolescent↗
Influence of chloroquine or acid treatment of human platelets on the antigenicity of HLA and the 'thrombocyte-specific' glycoproteins Ia/IIa, IIb, and IIb/IIIa.
The influence of treatment of platelets with citrate buffer (pH 7.2), chloroquine, or citric acid at pH 3 on the expression of HLA class I antigens and 'thrombocyte-specific' glycoproteins was investigated by means of flow cytometry. After treatment with citric acid at pH 3 and chloroquine, the expression of HLA class I was significantly reduced, while the density of the molecules GPIa/IIa, GPIIb, and GPIIb/IIIa (GP = glycoprotein) carrying 'thrombocyte-specific' antigens was not or only weakly decreased on the surface of the platelets. The use of two monoclonal antibodies (HC-10 and HC-A2) against the native heavy chain of the HLA class I molecule revealed that 'antigen stripping' with chloroquine or citric acid does not affect the entire molecule: only the beta 2-microglobulin is cleaved, or only some epitopes on the heavy chain are altered by this procedure. The treatment with citric acid yielded better results with respect to the removal of HLA class I activity and the preservation of 'thrombocyte-specific' glycoproteins. The presence of the heavy chain of HLA class I molecules on the surface of platelets after treatment with citric acid and chloroquine confirms the hypothesis that platelets--like nucleated cells--bear HLA class I antigens inserted in the cell by a cytoplasmic and a transmembrane domain.
Adult↗
Prospective multicentre study of risk factors associated with delayed healing of recurrent duodenal ulcers (RUDER). RUDER Study Group.
Risk factors for delayed duodenal ulcer healing during treatment with ranitidine (300 mg daily) were examined in a multicentre German study of 1923 patients with endoscopically proved, recurrent duodenal ulceration. Healing rates, per protocol, were 39.5% at two weeks, 70.9% at four weeks, and 93.2% at eight weeks. Prospective testing of five, predefined risk factors indicated that smoking (p = 0.0039) was associated with a decreased healing rate at two weeks. Frequent prior recurrence (p = 0.464), a heavy physical workload (p = 0.145), and psychological stress (p = 0.062) were not associated with a decreased healing rate and there were too few patients at risk to allow assessment of the effect of regular NSAID intake. Exploratory analysis identified prior slow healing, a large ulcer, multiple ulcers, and prior ulcer complications, in addition to smoking, as markers of slow healing. In the absence of these risk factors, the mean healing time was 3.3 weeks (95% confidence interval 3.0, 3.5), rising to 3.7 weeks (3.5, 3.9) for one, 4.4 weeks (4.1, 4.7) for two, and 5.1 weeks (4.5, 5.6) for three to five risk factors. Delayed duodenal ulcer healing is associated with multiple factors whose effect is cumulative; for patients with two or more of five easily identified risk factors, more than four weeks' treatment with a histamine H2 receptor antagonist is required to achieve ulcer healing.
Adult↗
Role of the PrP gene in transmissible spongiform encephalopathies.
The transmissible agent that causes spongiform encephalopathies such as scrapie, the prion, is believed to be devoid of nucleic acid and identical with PrPSc, a modified form of PrPC. PrPC is a normal host protein encoded by a single copy gene (Prn-p) and is found predominantly on the surface of neurons. PrPSc, in contrast to PrPC, is resistant to protease and accumulates intracellularly. Prusiner proposed that PrPSc, when introduced into a normal host, causes the conversion of PrPC or its precursor into PrPSc ('protein only' hypothesis). If indeed PrP is an essential component of the prion, then an animal devoid of the PrP protein should be resistant to scrapie. We generated homozygous PrP 'knockout' mice. These Prn-p0/0 mice showed no gross abnormalities, and microscopic examination of brain sections of normal and Prn-p0/0 mice revealed no differences. Prn-p0/0, Prn-p+/+ and Prn-p0/+ mice were inoculated with scrapie agent; the clinical response as well as the prion titer at different time points are being determined.
Animals↗
[Post-traumatic pain in the wrist, a diagnostic challenge].
Hyperextension of the wrist may induce underestimated intrinsic and extrinsic ligamentous tears. Undetected scaphoid fractures show the importance of accurate primary diagnostic. Evaluation of the anatomic and functional integrity of the ligaments of the wrist remains challenging. It requires great experience, but in any case, radiology remains the basic diagnostic tool used by both the general practitioner and the specialist. Only the use of reproducible imaging techniques will allow for comparison between healthy and pathological side as well as for follow-up. Every one should master and use standardized techniques as described in this paper. The costs bound to appropriate imaging techniques are certainly lower than the consequences of misdiagnosed ligamentous damage or carpal bone fractures. Furthermore, standardized techniques will avoid repeating radiological sessions.
Carpal Bones↗