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Biomedical subjects

J Kramer

Publications and source records attributed to J Kramer.

At least 73 records · Page 4Linked to original sources

[Radiologic and histologic observations in central talus fractures].

In a prospective study of central fractures of the talus, radiological data (plain radiography, CT, MRI) were scrutinized in terms of correlation with histological findings (biopsy taken at time of screw removal). The study looked at nine fractures in eight patients aged 14-48 years. There was one fracture of Hawkins type I, one fracture of type II, four fractures of type III, and three corpus fractures. All were operated on within 24 h after injury; seven had screw fixation, two had adaptation with K wires. The patients were kept non-weight-bearing for 14-53 weeks. Duration of follow-up was 2 years or more in all but one patient. In the final radiograph the talus was intact in four patients, while four showed a partial avascular collapse; in one patient, a partial collapse was doubtful. Histology taken 16-52 weeks after injury showed osteocyte-free original bone in all cases, with deposition of new bone varying in extent. Hawkins sign was partially positive in six patients, positive in one, and negative in one. Decalcification as well as fracture healing can be better followed by CT than by plain radiography. MRI appeared normal in five patients, partially pathological in two, and abnormal in one. A positive Hawkins sign and normal signal behavior can be seen as prognostically favorable signs. However, in the case of a central talus fracture, even with a favorable course osteonecrosis of at least a part of the talus with gradual replacement by new bone occurred. Vascularization of the central talus seems to be disturbed more frequently than is reflected radiologically.

Adolescent↗

Imaging of avascular necrosis of bone.

The etiology of avascular necrosis (AVN) is multifactorial. Independent of its etiology and localization it shows typical pathologies and radiological images. In the early stages localized subchondral edema is characteristic. In 50 % of all cases accompanying joint effusion may be found. Due to necrosis of the cells of bone marrow and bone fibrovascular, reactions with hyperemia can be delineated. These reactions allow us to visualize necrosis indirectly. The best imaging methods are MRI and, to a lesser extent, bone scintigraphy. In later stages calcification as well as new bone formation and microfractures are typically demonstrated and visualized best with plain X-rays and CT. Why reparations in many cases, particularly in the hip, are incomplete and may stop in any stage is unknown. Over years clinically complete silent AVNs are not an uncommon finding. Prognosis depends on the localization and size of the AVN. The number of repair mechanisms is best outlined with contrast-enhanced MRI and return of fatty marrow.

Bone and Bones↗

High resolution magnetic resonance imaging of neurovascular orbital anatomy.

PURPOSE: This study describes the magnetic resonance imaging (MRI) anatomy of the blood vessels and nerves of the orbit to provide a morphological basis for the interpretation of clinical findings. METHODS: Seven volunteers aged 29 to 54 years underwent high-resolution MRI of the orbit on a 1 Tesla unit (Impact, Siemens, Germany). T1-weighted oblique-sagittal, coronal, and axial images were obtained using a surface coil. Anatomic structures on the magnetic resonance images were identified by comparison with corresponding histologic sections of the orbit. RESULTS: The ophthalmic artery and most of its branches (central retinal artery, posterior ciliary arteries, lacrimal artery, anterior and posterior ethmoidal arteries, supratrochlear artery, supraorbital artery, dorsal nasal artery) are visualized. The superior ophthalmic vein, the lacrimal vein, the medial ophthalmic vein, the inferior ophthalmic vein, the medial and lateral collateral veins, and the vorticose veins are also delineated. Furthermore, branches of the oculomotor nerve, the abducens nerve, the frontal nerve, the nasociliary nerve, the lacrimal nerve and the infraorbital nerve are identified in the magnetic resonance images. CONCLUSION: High-resolution MRI is capable of delineating the orbital arteries, veins, and nerves. This is mainly based on two principles. First, blood vessels appear mostly dark on magnetic resonance images because of the signal void of flowing blood. Second, the bright background of the orbital fat on T1-weighted magnetic resonance images accounts for the good soft-tissue contrast in the orbit. With improved MRI technology and reduced imaging time, high-resolution-MRI may be applied routinely for diagnostic purposes.

Abducens Nerve↗

Genetic regulation of the impaired immune response to hepatitis-B vaccine associated with low TCR density in end stage renal disease patients: contribution of complement C4 and factor B alleles.

We have studied the relationship between T-cell receptor (TCR) density, genetic factors and the specific immune response in 153 end stage renal disease (ESRD) patients on haemodialysis immunised with HBsAg vaccine. One-hundred and nineteen patients raised a protective (> 10 U/ml) antibody response to hepatitis-B vaccination (responder, R), while 34 patients were found to be non-responders (NR). The density of the T-cell receptors was determined by flow cytometry. Proliferation of the T-cells induced by autologous monocytes presenting HBsAg was also measured and expressed as a stimulation index (SI). MHC class I, II and III alleles of the patients were also determined. The densities of TCR/CD3 receptors in NR patients were found to be significantly decreased as compared to the R patients (189 +/- 22 vs. 282 +/- 58 arbitrary units, P = 1.3 x 10(-7). TCR/CD3 receptor densities were found to be strongly associated (Spearman correlation coefficient: 0.84, P < 0.000001) with the SI values. Both parameters were found to be under dual genetic control: (a) very low density of the TCR/CD3 receptors and very low SI were found mainly in NR patients carrying HLA-A1, HLA-B8 and HLA-DR3 alleles; and (b) TCR/CD3 densities and function in R group were found to be significantly lower in carriers than in non-carriers of two MHC class III complement protein alleles: C4A*6, and Bf*F. Non-responsiveness to hepatitis-B vaccination was found to be associated with extremely increased neopterin levels. These findings indicate that both genetic and acquired factors contribute to the hepatitis-B vaccination failure in ESRD patients.

Alleles↗

A Canadian survey of issues in cancer pain management.

We report the analysis of a cancer management survey mailed to a representative group of health professionals in 1994. The goals of the study were to gather information on cancer pain treatment practices, and to obtain health professional views on obstacles to ideal pain management. The survey, designed by a working party of pharmacists, nurses and physicians, was distributed to 14,628 physicians. A total of 2,686 physicians responded to the survey, including 39% of medical or radiation oncologists, and 18.19% of physicians who listed their primary interest as Family Medicine. Reflecting the modest emphasis placed on palliative care and cancer pain management in the current Canadian milieu, 67% of physicians rated their past teaching experience as only "fair" or "poor." Lack of exposure to pain education was reflected in the response to a series of hypothetical case scenarios exploring physician choices in managing severe cancer pain. For example, in the initial management of a cancer patient with severe pain, 50% of physicians would not use a strong opioid in the absence of other contraindications to opioid use. A wide variety of analgesics and non-pharmacologic techniques is available to Canadian physicians to assist patients with pain. Few physicians identified the unavailability of analgesics or analgesic techniques as limiting factors in pain management. We conclude that greater emphasis should be placed on pain education in our training programmes. We suggest that further surveys of this type, sponsored by our provincial colleges and medical organizations, can provide feedback which will enhance the adherence by Canadian physicians to published guidelines for pain management.

Canada↗

High-resolution magnetic resonance imaging of the normal extraocular musculature.

PURPOSE: Magnetic resonance imaging (MRI) of the extraocular muscles has attracted growing interest for the evaluation of complex motility disorders. However, little information is available on the high-resolution MRI anatomy of the normal extraocular muscles and their connective tissue system. The study describes the imaging anatomy of the recti and oblique muscles and the levator palpebrae superioris muscle. METHODS: MRI of the orbit at 1 tesla was performed in four normal volunteers using a surface coil. RESULTS: Many anatomical details such as Zinn's tendinous annulus, the trochlea, the superior oblique tendon, the intermuscular septa, the check ligaments, Lockwood's ligament and the common sheath between the superior rectus muscle and the levator muscle were visualised. A striking imaging feature was the curved path of both the recti muscles and the levator palpebrae muscle. The inferior oblique muscle also showed a marked curvature in the region of Lockwood's ligament. CONCLUSIONS: High-resolution MRI is capable of demonstrating the anatomy of the extraocular musculature and parts of its connective tissue system. The curved path of the extraocular muscles can be explained by the configuration of the orbital connective tissue system which couples each extraocular muscle with the adjacent orbital wall. We discuss the clinical implications of our findings and review previous radiological studies regarding the functional anatomy of the extraocular muscles.

Adult↗

Comparisons of weight-bearing and non-weight-bearing tests of knee proprioception performed by patients with patello-femoral pain syndrome and asymptomatic individuals.

OBJECTIVE: To compare non-weight-bearing (sitting) and weight-bearing (standing, with approximately 95% of body weight on the test leg) tests of knee proprioception performed by patients with patello-femoral pain syndrome (PFPS) and asymptomatic individuals. DESIGN: A repeated measures design, repeated on two occasions. SETTING: Athletic injuries clinic. PARTICIPANTS: Seven men and 17 women with PFPS, and age- and sex-matched asymptomatic individuals. INTERVENTIONS: With their eyes closed, subjects extended their knee in sitting, or flexed their knees in standing, attempting to replicate target angles (15 degrees, 30 degrees, 45 degrees, and 60 degrees knee flexion) measured using an electrogoniometer. MAIN OUTCOME MEASURE: Observed angle of knee flexion during joint angle replication tests. RESULTS: Test-retest reliability coefficients (0.17-0.79) and between-session measurement error (+/-2.0 degrees to +/-6.4 degrees) varied widely. There was a tendency for reliability coefficients to be greater and between-session measurement error to be lower, for PFPS subjects, and for sitting tests. No significant differences were observed between the scores of the PFPS and asymptomatic subjects, at any of the four target knee angles. CONCLUSIONS: Scores in sitting should not be compared with those in standing. Clinically, the low reliability coefficients, large between-session measurement error, and finding of no statistically significant difference between PFPS and asymptomatic subjects suggest that the diagnostic value of the proprioceptive tests used is questionable. Further research is required to develop more precise tests of knee proprioception and to determine if the present results are applicable to other pathologies.

Adult↗

Histomorphology and bone morphometry of the bone marrow edema syndrome of the hip.

From a prospective study of patients with MR imaging proven bone marrow edema syndrome of the hip, bone biopsies that were retrieved at core decompression treatment of 32 femoral heads (from 28 men and 3 women; age range, 25-63 years) were evaluated microscopically. The undecalcified microtome sections showed diffuse or spotty areas of interstitial and intrasinusoidal fluid in the marrow cavities, together with fat cell destruction or fibrovascular regeneration or both in exactly the regions exhibiting the magnetic resonance signals for bone marrow edema. The vital bone trabeculae in these edematous regions showed more or less continuous, partly osteoblast covered osteoid seams, and often, formation of irregular woven bone (microcallus), pointing to increased bone formation activity. Preceding or active osteoclastic resorption was rarely seen. Computer assisted bone morphometry revealed age related normal to elevated bone volume densities (above 20% bone volume of tissue volume); thus, no evidence for osteoporosis was present. In addition to increased osteoid volumes, a decreased maximal hydroxyapatite content and a shift to undermineralized bone was found by mineral densitometry of corresponding microradiographs, when compared with age matched femoral heads without bone pathology. These bone mineral changes, but not transient bone loss, could be the explanation for the more or less subtle and transient radiolucency in hips affected by bone marrow edema syndrome. Live trabeculae and active bone formation, however, point to increased repair capacity, which seems the key for the spontaneously reversible course of this syndrome. There is still controversy whether the bone marrow edema syndrome represents a distinct transient disease or an early reversible phase of avascular necrosis, but because of the similarities in histopathology reported for early classic avascular necrosis and bone marrow edema in the literature and in the authors' own material, a common pathophysiology is discussed for these seemingly different diseases.

Adult↗

The life-time rates of three major mood disorders and four major anxiety disorders in alcoholics and controls.

AIMS: While psychiatric symptoms are common in the general population and even more prevalent in alcoholics, their clinical implications are not clear. The goal of this study was to establish the life-time rates of several independent and concurrent mood and anxiety disorders in alcoholics, controls and their relatives. DESIGN: Structured interviews were administered to alcoholics entering treatment, their relatives, and controls. SETTING: The study was carried out in six different centers in the United States as part of the Collaborative Study on the Genetics of Alcoholism (COGA). PARTICIPANTS: Data were gathered from 2713 alcohol dependent subjects (probands and their alcoholic relatives) and 919 controls. MEASUREMENTS: The timeline-based Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) interview was administered face to face by trained, closely supervised interviewers. The life-time rates for concurrent and independent disorders were determined for three DSM-III-R major mood and four major anxiety disorders. FINDINGS: Some form of independent mood disorder was seen during the life-time in slightly fewer alcoholics than controls (14.0% and 17.1%), but alcoholics did show higher rates of independent bipolar disorder (2.3% vs. 1.0%). The life-time rate for independent anxiety disorders was significantly higher in alcoholics than controls (9.4% vs. 3.7%), with most of the differential related to panic disorder (4.2% vs. 1.0%) and social phobia (3.2% vs. 1.4%), but no significant group differences for agoraphobia or obsessive-compulsive disorder. In general, these findings regarding mood and anxiety disorders were reflected in close relatives. CONCLUSIONS: The large majority of alcohol-dependent men and women in this sample did not have any of the independent mood or anxiety disorders evaluated here. However, there was evidence of enhanced risks among alcoholics for independent bipolar, panic and social phobic disorders. Studies which do not distinguish carefully between independent and concurrent mood and anxiety disorders in alcoholics are likely to report much higher rates of co-morbid psychiatric disorders than those that distinguish between the two types of syndromes.

Adult↗

High frequency of EEG and MRI brain abnormalities in panic disorder.

The frequency and quality of brain abnormalities in panic disorder (PD) were assessed with magnetic resonance imaging (MRI). The use of electroencephalography (EEG) to detect PD patients with a high probability of morphologic brain abnormalities was also explored. Consecutive PD patients (n = 120) were screened with routine EEG examinations and were divided into the following subgroups on the basis of their EEG findings: patients with non-epileptic EEG abnormalities (EEG-A group, n = 28), matched patients with normal EEG results (EEG-N group, n = 28) and matched healthy controls (n = 28). PD patients showed a higher than expected rate of non-epileptic EEG abnormalities (29.2%; 35 of 120). EEG screening was effective in identifying patients with a high probability of morphologic brain abnormalities. MRI abnormalities were found in 60.7% of the EEG-A patients, 17.9% of the EEG-N patients, and only 3.6% of the controls. A high frequency of septo-hippocampal abnormalities was found. Further research should focus on attempts to subtype PD on the basis of neuroanatomic and functional brain abnormalities.

Adult↗

Inherited complement C3 deficiency: reduced C3 mRNA and protein levels in a Laotian kindred.

To determine the molecular basis of complement C3 deficiency in a Laotian kindred, the homozygous C3-deficient male propositus was studied. By ELISA, this individual's serum was determined to contain approximately 4 microg/ml C3 (0.3% of normal). In accord with this result, anti-C3 immunoprecipitation of [35S]-methionine-labeled fibroblasts from this C3D individual revealed pro-C3 of normal size (180,000 Mr), but in significantly reduced amounts (approximately 1% of normal fibroblasts), that was processed and secreted with normal-size alpha- and beta-chains. In addition, C3-specific mRNA of normal size (5.2 kb) but in reduced quantity (approximately 1% of normal) was detected in this individual's fibroblasts by Northern analysis. The nucleotide sequence of the transcriptional initiation site, the promoter, and the IL-1beta/IL-6 cis-regulatory elements of the C3-deficient gene are normal in this C3-deficient individual, indicating that the low C3 mRNA and protein levels are not caused by reduced C3 transcription that is the result of a cis-mutation. Moreover, cDNA sequencing studies revealed no defect in the C3-deficient mRNA, including the areas mutated in four previously characterized C3-deficient patients. These data indicate that (1) C3 protein deficiency in this Laotian patient results from reduced levels of C3-specific mRNA, (2) the small amount of expressed C3 protein is processed and secreted normally from the deficient cells, and (3) the molecular genetic defect(s), although not yet delineated, is different from those described in other C3-deficient individuals, thereby providing additional evidence for numerous mutations that cause inherited C3 deficiency in humans.

Cells, Cultured↗

Infratentorial brain maturation: a comparison of MRI at 0.5 and 1.5T.

Our purpose was to establish parameters for normal infratentorial brain maturation at 0.5 and 1.5 T and to evaluate the field strength criteria for the assessment of infratentorial brain maturation with MRI. We examined 27 children with normal psychomotor development (3 days to 24 months) with a 1.5 T system and 22 (4 days to 29 months) with a 0.5 T system; standard T2-weighted spin-echo sequences (TR/TE 2500/90 ms at 1.5 T and TR/TE 2200/90 ms at 0.5 T) were obtained. The signal intensity of infratentorial anatomical structures compared to their surroundings was classified as high, isointense or low by three neuroradiologists. For anatomical structures with age-related contrast changes, the time of these changes was determined statistically for the 0.5 T and 1.5 T system independently. The delineation of the structures without age-related contrast changes at the two field strengths was compared using a chi 2 test. Age-related contrast changed were found in the same anatomical structures ("marker sites") at 0.5 and 1.5 T. Generally, these changes were apparent in larger structures (pons, middle cerebellar peduncles, medulla, cerebellar folia, red nuclei, cerebral peduncles), with only slight field-strength-dependent differences in the time of the contrast changes. Contrast changes from high to isointense signal were observed slightly earlier at 0.5 T and changes from isointense to low signal slightly later at 0.5 T. The delineation of the smaller anatomical structures was significantly better at 1.5 T but these structures did not show age-related contrast changes. The differences in the assessment of infratentorial brain maturation between 0.5 and 1.5 T can be attributed to a lower signal-to-noise ratio at lower magnetic field strengths. These differences do not complicate temporal classification of the stage of infratentorial brain maturation using the same "marker sites" and the same temporal criteria at 0.5 or 1.5 T. However, higher field strengths are preferable for the assessment of smaller structures with physiological signal differences; this may imply better detection of small lesions at higher field strengths.

Age Factors↗

What is the best way of assessing outcome after total knee replacement?

Variable definitions of outcome have been used in the past to assess the results after total joint replacement surgery. These differ in their approach to the measurement of outcome but all must be valid (they measure what they are designed to measure), reliable (they consistently produce the same score), and responsive (able to detect changes that may occur during a period). Responsiveness is crucial to distinguish those patients who benefit from a procedure from those who do not, and a more responsive test will theoretically be able to identify more subtle changes in patient status. The responsiveness of 6 different scoring systems was compared. The results are based on a cohort of 71 patients undergoing total knee arthroplasty in a 7-month period. Responsiveness was determined by performing a paired t test among each patient's scores at 0, 3, and 6 months. The size of the resulting t value represented the comparative responsiveness of the 6 tests. The highest value achieved was with the Western Ontario and McMaster Universities osteoarthritis index and the Knee Society clinical rating scale. The worst scores were achieved by Short Form-36 and time trade off, a utility method of measurement. If small differences between groups of patients are to be shown, measures of outcome that are more responsive to patient change should be used.

Activities of Daily Living↗

Functional anatomy of the levator palpebrae superioris muscle and its connective tissue system.

AIMS/BACKGROUND: The connective tissue system of the levator palpebrae superioris muscle (LPS) consists of the septa surrounding its muscle sheath, the superior transverse ligament (STL) commonly referred to as 'Whitnall's ligament' and the common sheath which is the fascia between the LPS and the superior rectus muscle (SRM). The anterior band-like component of the common sheath is called transverse superior fascial expansion (TSFE) of the SRM and LPS. It mainly extends from the connective tissue of the trochlea to the fascia of the lacrimal gland. A detailed description of the relation between the LPS and its connective tissue is presented. Furthermore, the course of the LPS in the orbit is described. The study was conducted to provide a morphological basis for biomechanical and clinical considerations regarding ptosis surgery. METHODS: Postmortem dissections were performed in 16 orbits from eight cadavers. The microscopical anatomy was demonstrated in six formalin preserved orbits from six cadavers which had been sectioned in the frontal and sagittal plane and stained with haematoxylin and azophloxin. Surface coil magnetic resonance imaging in the sagittal and coronal plane was performed in five orbits from five normal volunteers using a T1 weighted spin echo sequence. RESULTS: The STL and the TSFE surround the LPS to form a fascial sleeve around the muscle which has attachments to the medial and lateral orbital wall. The TSFE, which is thicker than the STL, blends with Tenon's capsule. The STL and the fascial sheath of the LPS muscle are suspended from the orbital roof by a framework of radial connective tissue septa. MR images show that the TSFE is located between the anterior third of the superior rectus muscle and the segment of the LPS muscle where it changes its course from upwards to downwards. In this area, the LPS reaches its highest point in the orbit (culmination point). The culmination point is located a few millimetres posterior to the equator and superior to the globe. CONCLUSION: Whitnall's ligament can be considered to consist of two distinct parts--the TSFE inferior to the LPS and the STL superior to the LPS. Since the medial and lateral main attachments of Whitnall's ligament are situated inferior to the level of the culmination point of the LPS, the ligament itself is unlikely to suspend the levator muscle. However, a suspension of the LPS may be achieved by the radial connective tissue septa of the superior orbit. The TSFE in connection with the globe may have an additional supporting function. The elasticity of Whitnall's ligament and its connections with highly elastic structures including Tenon's capsule, may provide the morphological substrate for the previously proposed passive (that is, without orbicularis action) lowering of the lid during downward saccades.

Adult↗

Lesions of the acetabular labrum: accuracy of MR imaging and MR arthrography in detection and staging.

PURPOSE: To determine the accuracy of magnetic resonance (MR) imaging and MR arthrography in the detection and staging of lesions of the acetabular labrum. MATERIALS AND METHODS: Fifty-seven hips of 56 patients with chronic hip pain and a strong clinical suspicion of labral lesions were examined with a three-dimensional gradient-echo sequence in the coronal oblique and sagittal oblique projections before and after the intraarticular injection of gadopentetate dimeglumine. The labra were evaluated on the basis of morphology, signal intensity, the presence or absence of a tear, and their attachment to the acetabulum. Twenty-two of the hips underwent surgical intervention, and 35 hips were treated conservatively. RESULTS: Twenty of the 22 labra with surgical proof were staged accurately with MR arthrography. On the conventional MR images, only eight of the 22 labra were staged correctly. Whereas the sensitivity of MR arthrography was 90% and its accuracy was 91%, the sensitivity of MR imaging was 30% and its accuracy was 36%, compared with surgical findings. CONCLUSION: MR arthrography enables accurate detection and staging of lesions of the acetabular labrum and appears to be indicated in the assessment of chronic hip pain in patients with a strong suspicion of labral lesions.

Acetabulum↗

Comparison between conventional and fast spin-echo stir sequences.

PURPOSE: To evaluate the common characteristics and differences in contrast behavior of short-TI-inversion-recovery (STIR) and short-TI-inversion-recovery fast spin-echo (TurboSTIR) sequences. MATERIAL AND METHODS: Phantoms doped with increasing doses of Gd-DTPA and a pork-fat phantom were used to evaluate the dependence of the STIR and TurboSTIR signals on the T1 relaxation time. Clinical TurboSTIR images were obtained from 30 patients with musculoskeletal abnormalities and compared to conventional STIR images in 15 cases and to postcontrast TurboSTIR images in another 15 cases. RESULTS: In the phantom measurements, a significantly shorter inversion time (TI) was needed to achieve fat suppression on TurboSTIR images, and, with an identical number of signal averages, contrast-to-noise ratios were lower on TurboSTIR images. These differences between STIR and TurboSTIR can be attributed to the contribution of stimulated echoes to overall TurboSTIR signal and can be compensated by a shorter TI and a higher number of signal averages for TurboSTIR, respectively. With these adaptations, clinical TurboSTIR and STIR images showed an identical contrast behavior with fat suppression and a high sensitivity to pathological lesions but TurboSTIR saved a significant amount of scan time and reduced some types of artifacts. Contrast uptake impaired lesion conspicuity on TurboSTIR images. CONCLUSION: TurboSTIR sequences should replace conventional STIR sequences and should be performed before contrast administration.

Adolescent↗

People with AIDS as residents: preparedness and acceptance by Connecticut long-term care facilities.

The management of AIDS has become an issue of chronic care as well as acute treatment. As the number of people with AIDS increases, the demand for ongoing care and support, both informal and formal, is expected to increase. The present study is based on a survey of all licensed nursing homes in the state of Connecticut with respect to prevailing attitudes toward the admission of residents with AIDS, and the level of staff, resident and procedural preparedness that exists. Both positive attitudes among the various LTC constituent groups as well as the level of preparation in a number of areas are correlated with the admission of residents with AIDS. Implications are discussed and recommendations are offered for policy development.

Acquired Immunodeficiency Syndrome↗