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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 235 records · Page 13Linked to original sources
PubMed1998

Effects of physiological hyperinsulinemia on systemic, renal, and hepatic substrate metabolism.

To determine the effect of physiological hyperinsulinemia on renal and hepatic substrate metabolism, we assessed systemic and renal glucose release and uptake, systemic and renal gluconeogenesis from glutamine, and certain aspects of systemic and renal glutamine and free fatty acid (FFA) metabolism. These were assessed under basal postabsorptive conditions and during 4-h hyperinsulinemic euglycemic clamp experiments in nine normal volunteers using a combination of isotopic techniques and renal balance measurements. Hepatic glucose release (HGR) and glutamine gluconeogenesis were calculated as the difference between systemic and renal measurements. Infusion of insulin suppressed systemic glucose release and glutamine gluconeogenesis by approximately 50% during the last hour of the insulin infusion (P < 0.001). Renal glucose release and glutamine gluconeogenesis decreased from 2.3 +/- 0.4 to 0.9 +/- 0.2 (P < 0.002) and from 0.52 +/- 0.07 to 0.14 +/- 0.03 micromol. kg-1. min-1 (P < 0.001), respectively. HGR and glutamine gluconeogenesis decreased from 8.7 +/- 0.4 to 4.5 +/- 0.5 (P < 0.001) and from 0.35 +/- 0.02 to 0.27 +/- 0.03 micromol. kg-1. min-1 (P < 0.002), respectively. Renal glucose uptake (RGU) increased from 1.61 +/- 0.19 to 2.18 +/- 0.25 micromol. kg-1. min-1 (P = 0.029) but accounted for only approximately 5% of systemic glucose disposal (40.6 +/- 4.3 micromol. kg-1. min-1). Both systemic and renal FFA clearance increased approximately fourfold (P < 0.001 for both). Nevertheless, renal FFA uptake decreased (P = 0.024) and was inversely correlated with RGU (r = -0.582, P = 0.011). Finally, insulin increased systemic glutamine release (P = 0.007), uptake (P < 0.005), and clearance (P < 0.001) but left renal glutamine uptake and release unaffected (P > 0.4 for both).

Adult↗
PubMed1998

Imaging of the liver with helical CT: a survey of scanning techniques.

OBJECTIVE: We conducted a survey of the members of the Society of Computed Body Tomography/Magnetic Resonance to assess current techniques in liver imaging using helical CT. MATERIALS AND METHODS: The survey, which was designed to update earlier surveys from 1987 and 1993, included a questionnaire distributed to 77 members of the Society of Computed Body Tomography/Magnetic Resonance. RESULTS: Forty-nine members responded, representing 28 institutions. In 1993, 19% (5/26) of institutions used helical scanners, compared with 82% (23/28) in 1996. The group of institutions with helical CT served as the focus of this survey. In 1993, 58% of institutions used 1-cm collimation: in 1996, 78% (18/23) used thinner, 7- to 8-mm collimation. In 1987, 41% used power injectors compared with 85% in 1993 and 100% in 1996. In 1996, monophasic injections were used by 96% (22/23) of institutions. In 1993, most institutions used a contrast material injection rate of 1.5-2.0 ml/sec; in 1996, most used a 2.5-3.0 ml/sec injection rate. In 1993, 96% of institutions used 125-150 ml of contrast material; in 1996, 57% (13/23) of institutions used 125-150 ml and 30% of institutions used less than 125 ml of contrast material. A delay time of 21-45 see was used by 83% of institutions in 1993, whereas in 1996, 83% (19/23) of institutions used a longer delay time of 50-80 sec. In 1996, 13% of institutions used an individual scan delay technology and all institutions performed multiphasic scanning of hypervascular lesions. CONCLUSION: The availability of helical CT has changed radiologists' approach to liver imaging. The greatest effects of which are a more widespread use of power injectors, longer delay times, thinner collimation, increased contrast material injection rates, decreased contrast material volumes, and multiphasic scanning.

Contrast Media↗
PubMed1998

Effects of autonomic neuropathy on counterregulation and awareness of hypoglycemia in type 1 diabetic patients.

OBJECTIVE: The recent EURODIAB Study has identified autonomic neuropathy as an independent risk factor for severe hypoglycemia in patients with type 1 diabetes. We tested the hypothesis that counterregulatory catecholamine responses and awareness of hypoglycemia are impaired to a greater extent in type 1 diabetic patients with autonomic neuropathy (AN+) than in those without autonomic neuropathy (AN-). RESEARCH DESIGN AND METHODS: We studied 22 type 1 diabetic patients (8 AN+, 14 AN-) matched for age, duration of diabetes, glycemic control, and history of hypoglycemic episodes. We also studied 33 nondiabetic control subjects using the stepped hypoglycemic clamp technique and determined glycemic thresholds and magnitudes of counterregulatory hormone responses and of hypoglycemia symptoms. RESULTS: Both groups of diabetic patients had reduced awareness of hypoglycemia as evidenced by an elevated glycemic threshold for autonomic symptoms > or =2 SD above normal but neither the magnitude nor thresholds for symptoms differed in AN+ patients and AN-patients. Both groups also had impaired glucagon, epinephrine, norepinephrine, growth hormone and cortisol responses to hypoglycemia. However, in AN+ patients compared with AN-patients, magnitudes of epinephrine and norepinephrine responses (194+/-49 vs. 784+/-206 pmol/l, P < 0.007, and 316+/-56 vs. 610+/-87 pmol/l, P < 0.02, respectively) and epinephrine and norepinephrine glycemic thresholds (2.33+/- 0.10 vs. 2.82+/-0.10 mmol/l, P < 0.009 and 2.34+/-0.06 vs. 2.79+/-0.10 mmol/l, P < 0.008, respectively) were impaired to a greater extent. This was associated with a 50% greater requirement of exogenous glucose to prevent more severe hypoglycemia during the 2.3 mmol/l glycemic plateau (P < 0.002). No differences were observed between other counterregulatory hormone responses in AN+ and AN- patients. CONCLUSIONS: We conclude that in patients with type 1 diabetes, autonomic neuropathy further reduces counterregulatory catecholamine responses. Since this should increase the risk for severe hypoglycemia, one might consider safer therapeutic goals in these patients.

Adult↗
PubMed1998

Enhanced proliferative activity of PIXY-321, the granulocyte-macrophage colony-stimulating factor and interleukin-3 fusion protein.

Previous studies with the granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) fusion protein, PIXY-321, demonstrated the enhanced biological activity of this molecule in comparison with GM-CSF or IL-3 alone or in combination. Here, we performed experiments to determine the proliferative effect of PIXY-321 on 13 constitutively growth factor-dependent human leukemia cell lines in comparison with GM-CSF, IL-3 and their combination using as read-out parameters the 48-hour 3H-thymidine incorporation assay and viable cell counts after in vitro culture for 7-8 days. Whereas one cell line was not responsive to any of these three cytokines, the other 12 cell lines showed variable degrees of growth in response to these effector molecules. PIXY-321 increased proliferation as measured by thymidine uptake relative to IL-3, GM-CSF or GM-CSF + IL-3 by 34% (range 5-448%), 12% (range 0-122%), and 6% (range 1-13%), respectively. PIXY-321 induced a mean increase of 32%, 30% and 11% in cell counts relative to the values obtained with IL-3, GM-CSF or GM-CSF + IL-3, respectively. Altogether, these data indicate that PIXY-321 stimulates proliferation of immature hematopoietic cells substantially better than equivalent concentrations of the single growth factors GM-CSF and IL-3. This hybrid growth factor showed a marginal to modest, but definite and reproducible increase in proliferation compared to the combination of GM-CSF plus IL-3. In summary, the fusion cytokine protein PIXY-321 appears to have biological effects superior to those elicited by its components, singly or in combination. This unique molecule should represent a useful tool in studies on the mechanisms underlying cytokine ligand-receptor interaction and the subsequent signal transduction. The use of PIXY-321 provides an opportunity for taking greater advantage in vitro and in vivo of the hematopoietic stimulatory activities of GM-CSF and IL-3.

Cell Division↗
PubMed1998

[Post-traumatic stress disorder after traffic accidents].

Posttraumatic stress disorder (PTSD) can occur after motor vehicle accidents (MVAs). It is an anxiety disorder characterized by intrusive reliving of the accident, avoidance of reminders of the trauma and increased arousal. Diagnostic criteria as specified in DSM-IV and in ICD-10 are discussed. A case example illustrates the features of PTSD incurred by MVA. An overview concerning the history of empirical studies on the consequences of MVAs is given. PTSD is one of the more common psychiatric disorders, with prevalence rates after MVAs ranging from 1% to nearly 9%. Other psychiatric and comorbid disorders that can occur as a consequence of MVAs are described. The present paper reviews the most influential etiological theories for PTSD. It describes and discusses current knowledge on risk factors for the development of PTSD after surviving an MVA. In the treatment of PTSD cognitive-behavioural approaches have proven to be the most effective interventions.

Accidents, Traffic↗
PubMed1998

Localization of a putative progesterone membrane binding protein in porcine hepatocytes.

A putative membrane bound steroid receptor was localized using a peptide specific antibody. Surprisingly, the distribution of immunocytochemical staining in porcine hepatocytes cells provides evidence for the localization to endomembranes (endoplasmic reticulum, Golgi apparatus). Immunofluorescence experiments with HEK cells, which were transfected with a pcDNA3.1 vector containing the coding sequence of the putative progesterone binding protein shows staining within the cells supporting these results. Additionally, 3H-progesterone binding and glucose-6-phosphatase activity as marker enzyme for endoplasmic reticulum were closely correlated in subcellular fractions of porcine liver cells.

Animals↗
PubMed1998

[Methods proposed for the determination of external forces applied to the mandible during mastication. Initial results].

The purpose of this study is to determine the external forces that are brought to bear on the mandible during various masticatory exercises. An analysis is presented of a static two-dimensional mandibular model taking into account projections in the sagittal plane of the forces exerted by six muscle groups and the joint reaction. In calculating the external forces, two working hypotheses are adopted: the existence of a linear relationship between cross-sectional surface of the muscle and its maximum force of contraction; the existence of a linear relationship between the electrical signal emitted by a muscle and the force the muscle then develops. It follows that, in order to calculate, the muscle forces, there is a need to measure the intensity of masticatory effort, the cross-sectional surface and the electromyographic activity of the different muscles involved. These values are then used for working out the equations of equilibrium. Results are provided for 14 masticatory exercises effected in three different mandibular positions and compared with data from literature. Individual variations recorded in the measurement of the different parameters involved in the equilibrium equations are such that they must be taken into account for the calculation of the forces. Moreover, the functional value of the muscles appears to be closely dependent on the mandibular position with which they are associated, which is not brought out in earlier studies. Finally, intra-joint action proves to be intense, although its direction varies according not only to the mandibular position but also the type of exercise performed.

Algorithms↗
PubMed1998

[Combined Latissimus dorsi and Serratus anterior reverse flow pedicle flap. Report of a clinical case].

The authors report a new local combined flap involving the distally based Latissimus dorsi muscle pedicled on the lumber perforating arteries and prolonged by the last three digitations of the Serratus anterior muscle supplied by the thoracic branch of the thoraco-dorsal artery. This artifice, never previously described, increased the bulk and arc of rotation of the dorsalis flap. It was thus possible to cover a wide defect on the posterior aspect of the sacro-iliac region in a patient previously operated for a highly malignant histiocytofibroma. The anatomic considerations, harvesting technique and advantages and drawbacks of this flap are discussed.

Adult↗
PubMed1998

[Laparoscopic treatment of gastroesophageal reflux using fundoplication. Midterm results].

UNLABELLED: The aim of this study was to see whether the results of surgical treatment of gastroesophageal reflux disease (GERD) by laparoscopic fundoplication were satisfactory and stable over time. PATIENTS AND METHODS: From July 1992 to September 1996, 161 patients with medical treatment-dependent GERD were operated. 17 patients were excluded from the study (conversion or immediate laparotomy). The group of 144 patients included consisted of 92 men and 52 women with a mean age of 50 (25-77 years). The preoperative work-up included endoscopy, esophageal manometry and 24-hour pH monitoring. The surgical procedures were complete fundoplication without section of the short vessels (Nissen-Rossetti: 122 cases), with section of the shorts vessels (Nissen: 18 cases), or partial fundoplication of 270 degrees (Toupet: 4 cases). The patients were reviewed clinically 3 months after the operation, with repeat manometry and pH monitoring; yearly survey was performed. RESULTS: There was no postoperative mortality. The morbidity consisted of 2 respiratory complications (1.5%) with good recovery. With a follow-up of 3 and 21 months, the dysphagia rate was 24 vs 2% of patients (p < 0.05), the rate of gas bloat syndrome was 18% vs 21% (n.s.), and the GERD recurrence 6% vs 14% (p < 0.05). The mean time to recurrence was 8 months. 2 patients were reoperated: one for incisional hernia and one for slipped-Nissen. CONCLUSION: The results of laparoscopic treatment of GERD with fundoplication procedures at 2 years follow-up showed an 86% cure rate of GERD control and 94% satisfaction rate for the patients who were investigated.

Adult↗
PubMed1998

[Long-term outcome of surgically treated orbital floor fractures. Apropos of a series of 242 patients].

Over a period extending from January 1993 to December 1995, we treated 242 patients with 268 orbital floor fractures in our department. Surgical indications were broad and relied on clinical criteria (enophthalmos, diplopia, hypoesthesia) and/or CT analysis (bony collapse, extrusion of orbital contents, suspicion of muscular entrapment, dislocation of the infraorbital rim). Two years after surgery, 91% of the patients showed good results (absence of diplopia or severe enophthalmos). The analysis of these results points out that the degree of sequelar enophthamos was not only related to the degree of initial bony collapse but above all to the quality of the bony reconstruction. Sequelar diplopia was linked with the presence of a preoperative diplopia and its severity was a direct function of operative delay. Hypoesthesia in the infraorbital nerve territory was the most common sequela; some were postoperative complications. The type of material used for the restoration of the orbital floor was not involved in the development of these sequela. Our good results suggest that an interventionist attitude is warranted in these kind of fractures, the more so as the X-ray examinations often underestimate injuries.

Adolescent↗
PubMed1998

[Stages of motivation to change in smokers of the general population].

Secondary preventive measures to reduce cigarette smoking can be effective only if the motivation to change in the target population is taken into account. A useful model to match interventions to the readiness to change differentiates five stages: precontemplation, contemplation, preparation, action, and maintenance. In the USA, general population studies showed that 40% of smokers were in the precontemplation and contemplation stage, respectively, and 20% were in the preparation stage. In Germany, no data according to the distribution of stages among smokers are available; however, such data are necessary to plan population-based interventions. Data with respect to nicotine use, nicotine dependence, and the stages of change were assessed in a representative sample of 4075 respondents in Luebeck, a northern German city, and 46 adjoining communities in a face-to-face interview. The response rate was 70.2%. In this sample, 37.3% were cigarette smokers. Of those smokers with at least one attempt to reduce or quite smoking in the past, 76.4% were in the precontemplation, 17% in the contemplation, and 6.6% in the preparation stage. Including individuals without an attempt to reduce or quit smoking, 95.3% can be allocated to the precontemplation or contemplation stage. Nicotine-dependent smokers were in higher stages compared to smokers without dependence. Severity of dependence was not related to the stages of change. Data demonstrate that common smoking cessation programmes that require the individuals' readiness to change are inappropriate for 95% of the population. Stage-matched interventions are introduced and discussed in the paper. Compared to data from the USA smokers in Germany are more likely to be in early stages of change. Policy-based public health measures are necessary to change these findings.

Adolescent↗
PubMed1997

Myocardial blood flow and glucose metabolism in diabetes mellitus.

Recent studies at our institution using positron emission tomography (PET) provide evidence that both myocardial blood flow (MBF) and glucose metabolism may be affected in patients with diabetes mellitus. A retrospective study revealed inadequate myocardial glucose uptake as assessed by 2-[18F]fluoro-2-deoxyglucose (18FDG) in 64% of type I (insulin-dependent diabetes mellitus, IDDM) and 36% of type II (non-insulin-dependent diabetes mellitus, NIDDM) patients. However, a study in 7 patients with IDDM and 9 controls showed that metabolic standardization using hyperinsulinemic-euglycemic clamp is associated with similar myocardial glucose uptake in both groups (0.43 +/- 0.16 vs 0.44 +/- 0.12 micromol/g per min; p = nonsignificant). Furthermore, we studied MBF as assessed by [13N]ammonia in 15 IDDM patients without coronary artery disease. We found an impairment in flow reserve in diabetic patients as compared with a control group of 13 healthy volunteers (2.6 +/- 1.3 vs 4.0 +/- 0.6; p <0.01), which was primarily due to a significantly higher resting MBF (95.3 +/- 27.7 vs 69.1 +/- 8.1 mL/100 g per min; p <0.01). Hyperemic flow during adenosine infusion tended to be lower in diabetics, but was not significantly different (236.3 +/- 105.7 vs 273.0 +/- 26.0 mL/100 g per min; p = nonsignificant). Morphologic and functional abnormalities of the coronary microcirculation have been reported in diabetic animals and humans. Furthermore, there is an ongoing controversy regarding the existence of a specific diabetic cardiomyopathy that is not related to epicardial coronary disease. However, few studies have explored the effect of diabetes, hyperinsulinemia, or hyperglycemia on MBF and glucose metabolism in humans. With PET it is possible to perform comprehensive noninvasive studies of various aspects of cardiac function in patients with diabetes mellitus.

Animals↗
PubMed1997

A revolving food pellet test for measuring sensorimotor performance in rats.

A revolving food pellet (RFP) test is presented, measuring the ability of rats to eat food pellets suspended from a horizontal bar in their home cage. This easy to make and economical device evaluates the efficiency of bilateral front paw coordination while standing. During the beginning of a ten day testing period, rats exposed to the RFP chamber had a lower intake of food and decreased body weight than rats housed in a standard home cage. With continued practice, the experimental group increased their food intake and body weight. During this time, the rats learned to control the revolving pellets by stabilizing them with their front paws and chewing on them. This apparatus is suitable for assessing a form of sensorimotor learning, involving the efficiency of front paw reaching, grasping, and holding movements, together with appropriate postural adjustments and biting movements. This test was sensitive to brain lesioning, as rats with bilateral lesions of the cerebellar fastigial nucleus were impaired.

Animals↗