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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 253 records · Page 14Linked to original sources
PubMed1997

Cognitive avoidance of threat cues: association with Eating Disorder Inventory scores among a non-eating-disordered population.

OBJECTIVE: This two-part study investigated the cognitive processing of food- and threat-related information in a non-eating-disordered population, particularly exploring the mechanisms that might explain the process of cognitive avoidance among women with bulimic attitudes. METHOD: In the first study, 30 female students solved anagrams of neutral, food, and threat words. In the second study, 50 male and female students solved anagrams of words reflecting physical threat, self-directed ego threat, and ego threat directed from others. RESULTS: In this task, there was no association between slower processing of threats and eating characteristics, but there were associations with Eating Disorders Inventory (EDI) scales that reflect "ego development." DISCUSSION: The most reliable evidence of cognitive avoidance was among those participants who show the ego development characteristics that have been identified as important in the development and etiology of eating psychopathology. The implications for models of eating psychopathology and their treatment are discussed.

Adolescent↗
PubMed1997

Background suppression with multiple inversion recovery nulling: applications to projective angiography.

We have developed a technique to accurately null the longitudinal magnetization (Mz) of background material. This suppression involves first saturating the longitudinal magnetization (Mz) of a region, and then applying several nonselective inversions. The inversions are timed relative to the saturation such that Mz is nulled across a broad range of T1 at a predetermined time after the initial saturation. B1 and B0 inhomogeneity, which could lead to inaccurate suppression, are dealt with by the combination of a multiple tip saturation sequence and four adiabatic inversion pulses. The suppression sequence can be used to form projective angiograms by selectively tagging the imaging region with the saturation pulse. After the inversions are played out, a projection taken through the tag region when Mz is nulled will only contain signal from blood that has flown into the region after the saturation. Since only two dimensions are acquired, the technique can acquire gated projection angiograms in reasonable scan times. Representative inflow MIR angiograms of the carotid arteries and renal arteries show excellent background suppression.

Carotid Arteries↗
PubMed1997

The arterial supply of the ankle joint and its importance for the operative fracture treatment.

The operative exposure of a fracture causes disturbances in the blood supply, which may lead to a prolonged healing process or even to bone necrosis, especially when using the complex and complicated methods of osteosynthesis at the ankle. In order to damage the supplying vessels as little as possible, position, direction and penetration of the bone arteries of the talocrural joint were examined by corrosion preparation. The tibial nutrient artery arises from the posterior tibial artery or from the popliteal artery and penetrates constantly from posterior at the level of the proximal third. The fibular nutrient artery, coming from the peroneal artery, penetrates more distally from medial into the middle third of the diaphysis. In one specimen it did not exist at all. Distal tibia and fibula are supplied by the perimalleolar arterial ring, which is connected with the three arteries of the leg. The talus is supplied by numerous very small vessels, which are provided with extraosseous anastomoses and penetrate the whole non-articular surface. Implications for the operation will be explained.

Adult↗
PubMed1997

Arterial supply of forearm bones and its importance for the operative treatment of fractures.

The operative exposure of a fracture in an osteosynthesis causes disturbances in the blood supply, which often leads to a prolonged process of healing or even to healing problems, a fracture non-union, which is frequently located at the forearm. In order to damage the supplying vessels as little as possible, the position, direction and penetration of the arteries of radius and ulna are demonstrated and systematised in this study. Near the elbow arteries, coming from large adjoining vessels, penetrate the area of the capsular insertion. The nutrient arteries enter both bones in the second proximal quarter of diaphysis, at the radius from anterior to medial, at the ulna from anterior to anteroradial. Small vessels, which penetrate closely proximal to the articular surface in order to supply the distal forearm bones, come from an anastomosis between the radial, the interosseous and the ulnar arteries. In this study access vessels, choice and position of implants will be discussed.

Aged↗
PubMed1997

Renal glucose production and utilization: new aspects in humans.

According to current textbook wisdom the liver is the exclusive site of glucose production in humans in the postabsorptive state. Although many animal and in vitro data have documented that the kidney is capable of gluconeogenesis, production of glucose by the human kidney in the postabsorptive state has generally been regarded as negligible. This traditional view is based on net balance measurements which, other than after a prolonged fast or during metabolic acidosis, showed no significant net renal glucose release. However, recent studies have refuted this view by combining isotopic and balance techniques, which have demonstrated that renal glucose production accounts for 25% of systemic glucose production. Moreover, these studies indicate that glucose production by the human kidney is stimulated by epinephrine, inhibited by insulin and is excessive in diabetes mellitus. Since renal glucose release is largely, if not exclusively, due to gluconeogenesis, it is likely that the kidney is as important a gluconeogenic organ as the liver. The most important renal gluconeogenic precursors appear to be lactate, glutamine and glycerol. The implications of these recent findings on the understanding of the physiology and pathophysiology of human glucose metabolism are discussed.

Animals↗
PubMed1997

Determination of molecular associations of some hydrophobic and hydrophilic bile acids by infrared and Raman spectroscopy.

The aim of this study was to analyse the Raman and infrared spectra of eight common mammalian bile acids in order to identify intermolecular interactions between hydroxyl and carbonyl groups. The results are considered in the light of the new hydrophilic/hydrophobic classification of bile acids. The alcohol OH group of the hydrophobic bile acids forms different intermolecular bonds. The most hydrophobic bile acid, lithocholic acid forms polymers, and this may explain its very low water solubility. The hydrophilic bile acids have some of their alcohol OH groups free of any intermolecular interaction. The strongly hydrophilic murideoxycholic acid also forms dimers, again consistent with a very low water solubility. The proposed structural arrangements are in agreement with published crystallographic studies.

Animals↗
PubMed1997

[Keratoplasty of pseudophakic eyes with posterior chamber lenses in Fuchs' dystrophy and secondary bullous keratopathy. Long-term outcome].

UNLABELLED: Penetrating keratoplasties in pseudophakia were added to a group with limited prognosis. This was especially valuable, if iris-supported and anterior chamber intraocular lenses were implanted. Since today mainly posterior chamber lenses are implanted, the question of the long-term prognosis in this type of lens is important. PATIENTS AND METHOD: From 1985 to 1994, 62 penetrating keratoplasties in pseudophakic eyes with posterior chamber IOL were performed: group I: decompensated Fuchs dystrophy (26 patients), group II: secondary surgery-related bullous keratopathy (36 patients) exclusively. Minimal follow-up was 18 months, mean age was 73.7 years. RESULTS: The mean follow-up period was 32 months. The mean visual acuity on delivery was 0.11. After 6 months it was 0.23, after 1 year 0.3, after 2 years 0.35 and after 3 years 0.41 without significant differences in either group. Two years after transplantation 52.8% gained a visual acuity (VA) of > or = 0.3, after 3 years 58.6% of which 41.1% had a VA of > or = 0.5. There was a visual improvement in 83.4%; the mean spherical equivalent was -0.29 D. Refractive errors within 2 D of emmetropia were found in 56.7%; 95.1% of the grafts remained clear. Five patients had a reversible graft rejection. Extracorneal factors of impaired vision were observed in 25 patients. CONCLUSION: Despite a different VA before surgery, the visual outcome in the two groups was identical. Penetrating keratoplasty in Fuchs dystrophy and secondary bullous keratopathy with posterior chamber IOL have a much better long-term prognosis than those with iris-supported and anterior chamber IOL. Postoperative complications and graft rejections are rare.

Aged↗
PubMed1997

Evidence for induction of polysaccharide specific B-cell-memory in the 1st year of life: plain Haemophilus influenzae type b-PRP (Hib) boosters children primed with a tetanus-conjugate Hib-DTPa-HBV combined vaccine.

UNLABELLED: The lack of an adequate immune response to the major polysaccharide of the Haemophilus influenzae type b (Hib) capsule (polyribosyl ribitol phosphate) (PRP) in very young infants (< 18 months) can be overcome by conjugating PRP to a T-cell dependent carrier protein. We studied whether administration of a tetanus-PRP conjugate vaccine reconstituted with a diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine as a three dose primary course at 3, 4 and 5 months of age induced PRP-specific immunological memory, by examining the anti-PRP response to a dose of unconjugated PRP given with the DTPa-HBV booster approximately 1 year later. The unconjugated PRP elicited protective anti-PRP antibody levels (> or = 0.15 microgram/ml) in all but 3 of the 369 vaccinees, including 13 infants who failed to demonstrate a measurable immune response after the primary course. In a sub-cohort of 54 subjects all had anti-PRP levels > or = 0.5 microgram/ml within 7-14 days of the booster showing a rapid anamnestic type response. Both primary and booster responses were predominantly IgGl indicating a T-cell dependent response. The DTPa-HBV components elicited protective anti-diphtheria, anti-tetanus and anti-HBs antibody levels in > or = 98.5% of vaccinees, and immune responses to each of the acellular pertussis vaccine components in 92.3%-97.3% of subjects. CONCLUSION: The tetanus-PRP conjugate vaccine not only elicited a good primary humoral response, but also induced immunological memory so that the infants were able to mount a large and rapid immune response to subsequent exposure to plain PRP, indicating that protection against circulating wild-type Hib had been generated. Successful induction of immunological memory occurred even when there was no measurable humoral anti-PRP response to the primary course. Tetanus-PRP conjugate vaccine can be used in combination with DTPa-HBV vaccine, when administered separately or as a single injection in the same syringe, in primary immunisation schedules at 3, 4 and 5 months of age.

Age Factors↗
PubMed1997

A model system in haematology and immunology: the human monocytic cell line MONO-MAC-1.

MONO-MAC-1 is a human cell line with properties of blood monocytes, which can be used as a model system to study monocytic functions in vitro. In the present study, we prepared a karyotype of MONO-MAC-1, analysed the growth behaviour, determined the presence of differentiation-associated antigens and studied the expression and secretion of several cytokines upon stimulation with 12-O-tetradecanoyl phorbol 13-acetate (TPA) and lipopolysaccharide (LPS). The MONO-MAC-1 cells have a near diploid karyotype and contain several recurrent chromosomal rearrangements, in particular the translocation (9;11) commonly found in AML-M5. Stimulation with TPA or LPS induced changes in morphology and gene expression, especially an increase in the level of the differentiation marker CD14 and the production of monocyte-related cytokines. Both biomodulators alone were sufficient to promote TNF alpha release; however, the combination of TPA and LPS resulted in a synergistic increase of TNF alpha secretion. Northern blot analysis indicated that upregulated production of TNF alpha was due to induced synthesis of mRNA. The mRNA accumulation peaked approximately 2 h after stimulation and maximum levels of TNF alpha were found in the supernatants after 4-8 h of culture. The MONO-MAC-1 cells could not be restimulated with the same inducer to release TNF alpha when a 48 h pre-treatment was carried out with LPS or TPA. LPS induced the release of granulocyte colony-stimulating factor (G-CSF), while TPA failed to do so. Vice versa, secretion of macrophage CSF (M-CSF) could be induced by TPA, but not by LPS. However, LPS enhanced the TPA-induced M-CSF production. Similarly, incubation of MONO-MAC-1, simultaneously with TPA and LPS, led to granulocyte macrophage CSF (GM-CSF) and interleukin-1beta (IL-1beta)secretion, while both stimulators alone had almost no (TPA) or only a weak (LPS) effect on the secretion of GM-CSF and IL-1beta. Our results demonstrate that MONO-MAC-1 is a unique cell line with distinct monocytic features; certain monocytic properties can be upregulated by activation of intracellular signalling pathway(s). We suggest that, besides the LPS receptor CD14, activation of PKC participates in these process, especially in the production and secretion of cytokines by MONO-MAC-1 cells.

Cell Line↗
PubMed1997

Patient expectations and recollection of information about photorefractive keratectomy.

PURPOSE: To assess the expectations of surgical result and recollection of a standardized information briefing by patients having photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, Medical University of Lübeck, Germany. METHODS: Thirty-two patients were asked to complete a multiple-choice questionnaire immediately after standardized information briefings and 1 month after PRK to establish their comprehension of the information briefing, what they remembered of it, and what they expected from the refractive procedure. RESULTS: Although the estimated intelligence quotient of the patients was above average (115 +/- 7.23) and almost all rated the information briefings as being comprehensible, only simple, basic facts about PRK were remembered immediately after the briefing as well as 1 month postoperatively. Of 12 possible undesired consequences, 6.4 were remembered before surgery and 3.9 after surgery. The latter were mainly side effects the patients experienced themselves. CONCLUSION: As most patients rejected the possibility of serious complications, for medicolegal reasons, careful, accurate documentation of the contents of and patients' satisfaction with the information briefing is necessary.

Adult↗
PubMed1997

Nitrite reductase expression is regulated at the post-transcriptional level by the nitrogen source in Nicotiana plumbaginifolia and Arabidopsis thaliana.

Higher plant nitrite reductase (NiR) is a monomeric chloroplastic protein catalysing the reduction of nitrite, the product of nitrate reduction, to ammonium. The expression of this enzyme is controlled at the transcriptional level by light and by the nitrogen source. In order to study the post-transcriptional regulation of NiR, Nicotiana plumbaginifolia and Arabidopsis thaliana were transformed with a chimaeric NiR construct containing the tobacco leaf NiR1 coding sequence driven by the CaMV 35S RNA promoter. Transformed plants did not show any phenotypic difference when compared with the wild-type, although they overexpressed NiR activity in the leaves. When these plants were grown in vitro on media containing either nitrate or ammonium as sole nitrogen source, NiR mRNA derived from transgene expression was constitutively expressed, whereas NiR activity and protein level were strongly reduced on ammonium-containing medium. These results suggest that, together with transcriptional control, post-transcriptional regulation by the nitrogen source is operating on NiR expression. This post-transcriptional regulation of tobacco leaf NiR1 expression was observed not only in the closely related species N. plumbaginifolia but also in the more distant species A. thaliana.

Arabidopsis↗
PubMed1997

Development of cytomegalovirus (CMV) disease may be predicted in HIV-infected patients by CMV polymerase chain reaction and the antigenemia test.

OBJECTIVE: Cytomegalovirus (CMV) is a frequent opportunistic viral pathogen in patients with AIDS leading to retinitis and other serious manifestations. CMV disease may be successfully treated. Prophylactic antiviral therapy has been shown to reduce the risk of CMV disease if initiated early. We evaluated PCR and the antigenemia tests as methods for early detection of CMV disease. METHODS: Two-hundred HIV-seropositive subjects with CD4 T-cell counts below 100 x 10(6)/l were monitored with CMV polymerase chain reaction (PCR), the antigenemia test, blood cultures and CMV immunoglobulin (Ig) G and IgM titres every second month for 1 year. RESULTS: Thirty-eight patients (19%) developed CMV disease. The PCR test detected CMV DNA a median of 46 days before onset of disease. This was earlier than the median of 34 for the antigenemia test and a median of 1 day for CMV blood cultures. Univariate analysis showed that the CMV PCR, the antigenemia test and blood cultures all had significant predictive values for subsequent development of CMV disease with odds ratios (OR) of 30, 22 and 20. CMV serology had no predictive value. Multivariate analysis showed that the PCR method was superior to the other tests; OR: CMV PCR 10.0, antigenemia test 4.4 and CMV cultures 4.3. No clinical parameters had any significant predictive value in the stepwise multivariate model. CONCLUSIONS: The CMV PCR and the CMV antigenemia tests are both sensitive methods that may predict development of CMV disease up to several months prior to clinical disease. These methods make it possible to select patients at high risk for CMV disease and suitable for prophylactic therapy against CMV.

AIDS-Related Opportunistic Infections↗
PubMed1997

A [2Fe-2S] ferredoxin (FdVI) is essential for growth of the photosynthetic bacterium Rhodobacter capsulatus.

The physiological function of Rhodobacter capsulatus FdVI, a [2Fe-2S] ferredoxin, was investigated by the cloning, sequence analysis, and mutagenesis of its structural gene, called fdxE. The DNA region surrounding fdxE was mapped, and the nucleotide sequence of a 4.2-kb fragment was determined. fdxE is preceded by a sequence that is very similar to a sigma54 recognition site and is followed by a putative transcription stop signal, suggesting that fdxE forms a separate cistron. Two open reading frames were identified upstream and downstream of fdxE and were named ORFE0 and ORFE1, respectively. The former may encode a polypeptide having 34% similarity with HtrA, a serine protease found in enteric bacteria. ORFE1 is homologous to purU, a gene involved in purine biosynthesis. Interposon mutagenesis of fdxE was unsuccessful when attempted on the wild-type strain B10. Disruption of fdxE could be achieved only in strains harboring an additional copy of fdxE on a plasmid. Mutants obtained in this way and carrying a plasmid-borne copy of fdxE under the control of the nifH promoter grew only in N-free medium, thus demonstrating that fdxE expression is required for growth. Nevertheless, such mutants were found to spontaneously revert at a frequency of 5 x 10(-6) to an apparent wild-type phenotype, although they contained no detectable amount of FdVI. Taken together, the results indicate that FdVI is required for an essential metabolic function in R. capsulatus and that this FdVI dependence could be relieved by a single-mutation event. In accordance, FdVI biosynthesis was found to be constitutive in R. capsulatus.

Bacterial Proteins↗
PubMed1997

Cellular mechanism of aminoglycoside tolerance in long-term gentamicin treatment.

In the rat, nephrotoxicity results from uptake of gentamicin at the apical membrane of proximal tubule (PT) cells. However, during continuous gentamicin treatment, the PT epithelium has been shown to recover. The mechanism(s) of cellular recovery and development of tolerance remains unknown. Therefore, we undertook studies designed to characterize cellular adaptations that occur during long-term gentamicin (LTG) treatment. After 19 days of gentamicin treatment, electron microscopy morphological evaluation revealed cellular recovery with an apparent mild decrease in height and number of microvilli. Enzymatic analysis of LTG PT membranes showed that apical and basolateral membranes had essentially returned to normal. Analysis of apical membrane lipid content revealed persistent statistically significant (P < 0.01) elevations in phosphatidylinositol (PI). In vivo immunogold morphological studies and biochemical studies in LTG rats revealed that endocytosis of gentamicin was selectively reduced, whereas the markers of fluid-phase (horseradish peroxidase) and receptor-mediated (beta2-microglobulin) endocytoses were unaffected or increased. Biochemical analysis showed that, although gentamicin binding to apical membranes isolated from LTG rats increased greater than twofold (P < 0.05) over membranes from untreated rats, in vivo cellular uptake, quantified with [3H]gentamicin, was reduced. Western blot analysis of LTG apical membranes and immunofluorescent staining of perfusion-fixed LTG kidneys showed no change in megalin levels or its apical membrane localization. These data imply that recovery of PT cells from and tolerance to LTG treatment involve a selective inhibition of gentamicin uptake across the apical membrane. They indicate that the mediators of gentamicin endocytosis were affected differently: PI levels increased, whereas megalin levels did not change. We conclude that selective inhibition of gentamicin uptake during LTG treatment is not affected by a reduction in PI or megalin levels. We postulate that trafficking of gentamicin and/or gentamicin-containing endocytic structures is reduced in LTG rats, allowing cells to develop tolerance to gentamicin.

Adaptation, Physiological↗
PubMed1997

Steady-state and non-steady-state measurements of plasma glutamine turnover in humans.

To compare steady-state glutamine turnover using nitrogen, carbon, and hydrogen tracers and to test the validity of monocompartmental equations to determine plasma glutamine turnover under non-steady-state conditions, we infused 10 normal postabsorptive volunteers simultaneously with [3,4-3H]glutamine, [2-15N]glutamine, and [U-14C]glutamine for 4 h to isotopic steady state. Eight of the ten subjects were subsequently infused in a stepwise fashion with exogenous glutamine. Plasma glutamine enrichment and specific activities fit a monoexponential model well (r = 0.89, 0.92, and 0.92 for [2-15N]-, [U-14C]-, and [3,4-3H]glutamine, respectively). Volumes of distribution for each tracer (362 +/- 58, 433 +/- 51, and 446 +/- 63 ml/kg) and the transfer rate constants (0.0224 +/- 0.0020, 0.0222 +/- 0.0020, and 0.0240 +/- 0.0023 min(-1)) for [2-15N]-, [U-14C]-, and [3,4-3H]glutamine, respectively, were not significantly different from one another. However, turnover of glutamine determined with [3,4-3H]glutamine (6.14 +/- 0.54 micromol x kg(-1) x min(-1)) exceeded that determined with [U-14C]glutamine (5.72 +/- 0.541 micromol x kg(-1) x min(-1); P < 0.03), which in turn exceeded that determined with [2-15N]glutamine (4.67 +/- 0.39 micromol x kg(-1) x min(-1), P < 0.01). The monocompartmental non-steady-state equations of both DeBodo et al. (DeBodo, R., R. Steele, A. Dunn, and J. Bishop. Rec. Prog. Horm. Res. 19: 445-448, 1963) and Finegood et al. (Finegood, D., R. Bergman, and M. Vranic. Diabetes 36: 914-924, 1987) yielded acceptable approximations of predicted rates of glutamine plasma appearance with deviations from predicted rates from 0.2 to 1.6% (Finegood et al.) and from 0.1 to 8.2% (DeBodo et al.). Use of a 0.75 pool fraction most closely approximated predicted rates.

Adult↗