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Biomedical subjects

J Kramer

Publications and source records attributed to J Kramer.

At least 55 records · Page 3Linked to original sources
PubMed1998

Morphological dissociation between visual pathways and cortex: MRI of visually-deprived patients with congenital peripheral blindness.

MRI was used to study possible morphological changes in the visual system in 12 patients suffering from congenital blindness of peripheral (ocular) origin. While their optical pathways showed degeneration, hypoplasia or atrophy in 7 out of 12 cases, the occipital cortex appeared normal in all cases. This dissociation between afferent pathways and the cortex is contrary to the assumption that visually deprived cortex may undergo degeneration. The finding is congruent with evidence that the occipital cortex is used for other, nonvisual functions.

Adult↗
PubMed1998

Endothelial cells cultured from human brain microvessels produce complement proteins factor H, factor B, C1 inhibitor, and C4.

The inflammatory mediators, cytokines and complement proteins are believed to regulate the sequential events during the development of lesions secondary to ischaemia and reperfusion. The endothelial cell monolayer of the brain microvasculature is the critical interface between the blood-borne mediators and brain tissue. The involvement of these cells in complement production and regulation has not been well documented. In the present study, expression of complement proteins (C1 inhibitor, factor H, factor B, C4) by cultured endothelial cells obtained from human brain microvessels has been characterized. Interferon gamma upregulates the production of all the complement factors studied. Serine proteases, plasmin and miniplasmin induce the expression of C4, decrease the level of ELISA detectable C1 inhibitor, and do not affect the production of factors H and B. These data indicate that complement proteins are expressed locally by the brain microvessels, and may modulate the inflammatory responses of brain tissue.

Brain↗
PubMed1998

Cytokine regulation of the acute-phase protein levels in multiple myeloma.

BACKGROUND: Interleukin (IL) 6 has an important role in the regulation of acute-phase proteins (APPs) during an acute-phase response. We studied IL-6 and other cytokines to determine if they regulate serum APP levels in the same way under the condition of the aberrant, long-lasting 'acute-phase response' that occurs in patients with chronic inflammation and cancer. METHODS: Serum levels of nine positive APPs [CRP, SAA, C1-INH, Bf, C5, C8, C9, alpha 1-acidic glycoprotein (AGP) and haptoglobin] and two negative APPs [transferrin and alpha 2-HS glycoprotein (AHSG)] were measured using immunochemical methods in 59 multiple myeloma patients and in 72 healthy control subjects. Serum IL-6 and tumour necrosis factor (TNF) alpha levels were determined by bioassays. RESULTS: IL-6 was negatively correlated with five out of nine (C1-INH, C8, C9, AGP and haptoglobin) positive APPs but positively correlated with C-reactive protein (CRP). When patients with high and low IL-6 serum concentration were compared, CRP levels were higher, AGP and haptoglobin levels were lower in the high- than in the low-L-6 group, whereas no significant difference between the two groups was found in levels of the other positive and negative APPs. TNF-alpha levels were negatively correlated with transferrin and AHSG levels. No difference in the levels of positive APPs was observed between patients with low and high TNF-alpha serum concentration. By contrast, levels of both transferrin and AHSG were significantly lower in the high- than in the low-TNF-alpha group. CONCLUSIONS: These findings indicate that, except for regulation of the negative APPs by TNF-alpha, the mechanism of APP regulation is different under the conditions of the short-term and the chronic, long-lasting 'acute-phase reaction'.

Acute-Phase Proteins↗
PubMed1998

IgA content of washed red blood cell concentrates.

Saline-washed red blood cell (RBC) concentrates are largely depleted of leukocytes, microaggregates, and nearly of all plasma originally contained in the blood unit. Our aim was to determine the concentration of the eliminated IgA and total protein in the buffy coat and plasma removed RBC concentrate before and after a sequential dilution-centrifugation washing procedure, 75.3% protein, and 99% IgA were eliminated by the washing process used. The recovery of red blood cells was 87.2%. Our results have led to the conclusion that two sequential washings seem to guarantee an IgA level of less than 0.2 mg/unit to meet the recommendations of the Council of Europe. Additional advantages of washing include low levels of extracellular hemoglobin, metabolic waste products and debris in the supernatant.

Blood Component Removal↗
PubMed1998

High-resolution magnetic resonance imaging of the orbital connective tissue system.

A complex system of connective-tissue septa within the orbit has previously been described in serial histologic sections. The present study describes the anatomy of the orbital connective tissue system on high-resolution magnetic resonance (MR) images in vivo. Five volunteers aged 26 to 35 year underwent magnetic resonance imaging of the orbit on a 1 Tesla unit (Impact, Siemens, Germany). T1-weighted coronal images were obtained using a surface coil. Anatomical structures on the MR images were identified by comparison with corresponding histologic sections. On MR images of the anterior orbit, the levator aponeurosis, Lockwood ligament, transverse intermuscular ligament, common sheath, check ligaments, Tenon capsule, intermuscular septa, and palpebral ligaments can be seen. In the mid- and posterior orbit, the intermuscular orbital septa, especially the superolateral septum, the superior ophthalmic vein hammock, and septa of the radial connective tissue system are visualized. High-resolution magnetic resonance imaging is capable of delineating the major septa of the orbital connective tissue system.

Adult↗
PubMed1998

Sendai virus-like particles devoid of haemagglutinin-neuraminidase protein infect cells via the human asialoglycoprotein receptor.

Virus-like particles with genetically defined envelope proteins were generated from cDNA in order to examine the requirement of Sendai virus haemagglutinin-neuraminidase (HN) protein for particle formation, and the role of fusion protein (F) in receptor binding and membrane fusion. Characterization of particles devoid of HN protein showed that particle formation was unimpaired by the absence of HN protein, indicating that HN protein is dispensable for virus assembly and budding. Infection studies further demonstrated that virus adsorption and penetration can be mediated solely by the F protein when the human asialoglycoprotein receptor is present at the surface of host cells.

3T3 Cells↗
PubMed1998

Dynamic magnetic resonance imaging of the levator palpebrae superioris muscle.

The relationship between upper lid elevation (h) and shortening (s) of the levator palpebrae superioris muscle (LPS) has an influence on the dose-response relationship in ptosis surgery. In order to investigate the relationship between upper lid elevation and shortening of the LPS, parasagittal T1-weighted MR images of the orbit were obtained in healthy subjects with the eye in down- and upgaze. The position of the upper lid margin and the length of the LPS were measured in the images in down- and upgaze and the amount of h and s was determined. For a mean (+/- SD) vertical upper lid elevation of 15 +/- 1 mm, the mean (+/- SD) shortening of the LPS muscle was 21 +/- 3 mm (n = 4). The mean ratio of his was calculated to be 1:1.4, which means that the levator muscle must contract by 1.4 cm in order to achieve a lid elevation of 1 cm. Therefore, the force of the LPS which is necessary to lift the upper eyelid can be smaller than the lid-closing force. This strongly suggests a physiological mechanism which reduces the muscle force necessary for lifting the upper eyelid.

Adult↗
PubMed1998

Evaluation of mild lameness in horses trotting on a treadmill by clinicians and interns or residents and correlation of their assessments with kinematic gait analysis.

OBJECTIVE: To estimate sensitivity and accuracy of subjective evaluation of mild lameness in horses during treadmill locomotion and to correlate subjective evaluation with kinematic analysis. ANIMALS: 19 lame and 5 clinically normal horses. PROCEDURE: Lameness was evaluated by subjective score and kinematic analysis before and after palmar digital nerve block (PDNB). Evaluations were made by 6 clinicians and 7 interns or residents. Within- and between-observer agreement analyses (kappa values) were calculated and compared, using a Student's t-test. Pearson's product-moment correlation coefficients were calculated between clinician's change in score and the change in kinematic variables after PDNB. RESULTS: Within-observer agreement was within the range expected for conditions of moderate diagnostic difficulty. Within-observer agreement was higher for clinicians than for interns or residents. Between-observer agreement was acceptable for scores within 1 value of each other. Between-observer agreement of change in lameness score after PDNB was poor. When kinematic variables were ranked with each clinician's subjective change in score, only 2 were among the top 3 for the majority of clinicians. Asymmetry of vertical head movement between contralateral forelimb stance phases and the point of maximum hoof height during swing decreased as lameness subjectively improved. CONCLUSION: Mild lameness may be difficult to evaluate during treadmill locomotion. Although clinicians were more repeatable in their subjective evaluation of lameness than interns or residents, they were not more reliable at detecting the true state of lameness. CLINICAL RELEVANCE: Lack of agreement between clinician scoring of mild lameness emphasizes the need to use more objective measures for quantifying lameness.

Animals↗
PubMed1997

[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↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

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↗
PubMed1997

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↗