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J Meyer

Publications and source records attributed to J Meyer.

At least 613 records · Page 34Linked to original sources
PubMed1992

Stretch-activated non-selective cation channels in the antiluminal membrane of porcine cerebral capillaries.

1. Single stretch-activated (SA) channels have been studied in isolated brain capillary endothelial cells as well as in the antiluminal membrane of intact porcine cerebral capillaries using the patch-clamp recording technique. 2. The SA channels were found to be cation selective and permeable to Na+, K+, Ba2+ and Ca2+. 3. With monovalent cations in the patch pipette, the channels showed inward rectification in cell-attached patches with a single-channel conductance of 37 pS at negative and 24 pS at positive clamp potentials. 4. With either 70 mM-Ca2+ or Ba2+ in the patch pipette, the current-voltage relation was linear with slope conductances of 16 and 19 pS, respectively. 5. Mean channel open probability increased with increasing pressure and with depolarizing clamp potentials. 6. Cell swelling induced by hypotonic shock activated the SA channels in cell-attached experiments. 7. The SA channel may be involved in cell volume or blood flow regulation. The contribution of these channels to the regulation of cerebrospinal salt and water content, especially in brain oedema, is discussed.

Animals↗
PubMed1992

Serum erythropoietin concentrations in symptomatic infants during the anaemia of prematurity.

A comparison was carried out between a series of neonates who weighed less than 1500 g at birth and received red cell transfusions for symptomatic anaemia of prematurity (group 1, n = 14) and controls of similar gestational age and weight, who remained well and were not transfused during their nursery stay (group 2, n = 10). Mean (SD) haemoglobin concentrations at birth were 163 (12) g/l and 183 (17) g/l (p = 0.004), respectively. Transfusion resulted in significantly better weight gain in six infants who had been growing poorly:mean (SE) 8.8 (2.8) g/day improved to 23.3 (2.1) g/day (p less than 0.002). Geometric mean (SD) serum immunoreactive erythropoietin (SiEp) concentrations (17.7 (1.3) U/l) for the whole group of infants were similar to those of normal adults (17.4 (4.7) U/l) despite considerably reduced haemoglobin values. There was a significant inverse correlation between haemoglobin and log SiEp concentrations in the infants requiring transfusion (r = -0.43; p less than 0.01), but this was not apparent in the untransfused babies. Moreover, at haemoglobin concentrations below 120 g/l the mean (SE) SiEp concentration of 20 (1.08) U/l in group 1 was significantly higher than in group 2 (14 (1.06) U/l; p = 0.002). These data suggest that an increased concentration of SiEp early in the course of the anaemia of prematurity helps to identify those infants who would benefit from red cell transfusions, but that clinical criteria, although ill defined, do so equally well.

2,3-Diphosphoglycerate↗
PubMed1992

Reversal of hyperdynamic response to continuous endotoxin administration by inhibition of NO synthesis.

Septic shock is characterized by an increase in cardiac output and a fall in systemic vascular resistance index and mean arterial pressure. Endotoxin alters the smooth muscle function of blood vessels, probably by means of an increased production of the potent vasodilator nitric oxide (NO). The present study was accomplished to determine how the inhibition of NO synthesis influences cardiovascular performance in an ovine model of hyperdynamic endotoxemia. Endotoxemia was induced in five range ewes (41 +/- 2 kg) by continuous infusion of Escherichia coli endotoxin (LPS, 10 ng.kg-1.min-1) over the entire study period. After 24 h of LPS infusion, cardiac output increased from 5.2 +/- 0.3 to 7.9 +/- 0.6 (SE) 1/min (P less than 0.05) and mean arterial pressure and systemic vascular resistance index fell from 92 +/- 5 to 79 +/- 6 mmHg (P = 0.08) and from 1,473 +/- 173 to 824 +/- 108 dyn.s.cm-5.m2 (P less than 0.05), respectively. The pulmonary shunt fraction increased from 0.23 +/- 0.03 to 0.32 +/- 0.03 (P less than 0.05). The intravenous administration of the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (25 mg/kg) 24 h after the start of the LPS infusion changed these values to approximately baseline levels over the subsequent 4 h. Although N omega-nitro-L-arginine methyl ester increased pulmonary arterial pressure and pulmonary vascular resistance (P less than 0.05), right and left ventricular stroke volume index showed no significant changes. It is concluded that NO has a major function in cardiovascular performance in endotoxemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Treatment of pain with pancreatic extracts in chronic pancreatitis: results of a prospective placebo-controlled multicenter trial.

According to the theory of negative feedback regulation of pancreatic enzyme secretion by proteases, treatment with pancreatic extracts has been proposed to lower pain in chronic pancreatitis by decreasing pancreatic duct pressure. We conducted a prospective placebo-controlled double blind multicenter study to investigate the effect of porcine pancreatic extracts on pain in chronic pancreatitis. 47 patients with pain (41 males, 6 females) due to chronic pancreatitis documented by sonography, endoscopic retrograde cholangiopancreatography, and CT were included. Exclusion criteria were steatorrhea above 30 g/day, gastric or pancreatic resections in the history, and serum bilirubin above 1.5 mg/dl. Patients received pancreatic extracts (acid-protected microtablets; Panzytrat -20,000; 5 x 2 capsules/day; proteases/capsule 1,000 Pharmacopoea europaea units) for 14 days followed by treatment with placebo for another 14 days or vice versa. Pain (graded from 0 to 3) and concomitant use of analgesics (N-butylscopolaminiumbromide and tramadol) were recorded by diary. Physical examination and blood chemistry were done at day -1, 15 and 29. Quantitative stool fat was determined at days -2/-1, 13/14 and 27/28. 43 patients completed the studies. Pain improved in most patients irrespective of whether they started with placebo or verum. There was no significant difference between both treatment arms. We conclude that pancreatic extracts are not very efficient in lowering pain.

Adult↗
PubMed1992

[Acetylsalicylic acid in unstable angina, after coronary revascularization and in prevention of cardiac thromboembolism].

Acetylsalicylic acid (ASA) inhibits platelet function via cyclooxygenase inhibition. The selective inhibition of platelet cyclooxygenase is possible with the use of low doses of ASA due to presystemic acetylation of the platelet enzyme in the portal circulation. The clinical efficacy of ASA has been demonstrated for a number of indications. ASA reduces the rate of myocardial infarctions and cardiovascular deaths in patients with unstable angina. Simultaneous intravenous infusion of heparin has an additional positive effect. The prevention of acute coronary thromboses during PTCA and of early bypass graft occlusion has been convincingly demonstrated, if therapy is initiated immediately after surgery. Neither ASA nor any other drug has been effective in the prevention of late restenosis following PTCA and of late bypass graft occlusions. Thromboembolic complication after implantation of biological valve prostheses is significantly reduced by ASA, if no rheumatic valve disease is present. The rate of peripheral or cerebral thromboembolic events is markedly increased in patients with lone atrial fibrillation. In contrast to the very positive results obtained for anticoagulants, the reports with ASA were contradictory. ASA may be effective in preventing thromboembolic complications in younger patients with a lower risk or in elderly patients with contraindications for anticoagulation. For most clinical indications the efficacy of ASA has been demonstrated for doses of 75-324 mg/d. Following a loading dose of 300 mg on the first day, continuation of therapy with 100 mg/d should combine maximal therapeutic efficacy with a low rate of unwanted drug effects.

Angina, Unstable↗
PubMed1992

[Determinants of lead concentration in the umbilical cord blood of 9189 newborns of a birth cohort in the government district of Braunschweig].

From September 1985 until August 1986 the possibility of lead concentration determination in umbilical cord blood was offered to all neonates in the district of Braunschweig by the Ministry of Social Affairs of Lower Saxony. A geometric mean concentration of 3.76 +/- 1.69 micrograms Pb/dl was found in 9189 neonates, being 64% of the total birth cohort. The median concentration was 3.59 micrograms/dl. 4.7% of the children showed concentrations of above 10 micrograms/dl. Lead concentrations of twins showed a strong linear correlation (r = + 0.94). They were higher than those of singleton births (p = 0.02). Lead concentrations in neonates were significantly associated with the age of the mother and with the birthweight of the newborn. Seasonal differentials were significant with higher values in summer (4.39 +/- 1.8 micrograms Pb/dl) compared to winter (3.25 +/- 1.5 micrograms/dl). Duration of daily participation in road traffic was independent of blood lead concentrations. Potential occupational lead exposure of a member of the household was also no significant risk factor for higher lead concentration in the newborn. Family homes constructed before 1955 and those with lead water pipes were associated with significant increases of lead concentrations in neonates. Neighborhood was also significantly associated, with higher values in those living by main roads. In the southern part of the district lead concentrations were about 10% higher than in the northern part. Concentrations in neonates coming from cities were the same as in those coming from rural areas. Newborns from old lead mining and processing areas in the Harz mountains, in particular those coming from Oker-Harlingerode, had low lead concentrations in umbilical cord blood.

Cohort Studies↗
PubMed1992

The effect of intermediate altitude on the Army Physical Fitness Test.

Official physical training records of personnel stationed at intermediate altitude (elevation 5,280 feet) for at least 1 year were reviewed to gauge the effect of altitude on 2-mile running performance. An average of 48 additional seconds (a 5% increase in time) was required to complete the run compared to sea-level values in the same subjects. Run times gradually diminished during the first 9 months of assignment to altitude before stability was established. These data indicate that acclimatization occurs over several months. Even with acclimatization, substantial loss of performance is associated with habitation at intermediate altitude.

Adult↗
PubMed1992

[Noninvasive quantification and classification of the severity of aortic stenosis using Doppler echocardiography].

The exact determination of the severity of valvular heart disease represents the basis for the indication for surgery. Apart from the clinical findings, the estimation of the severity has, up to now, been based on the chest x-ray, the electrocardiogram, and the carotid pulse curve. By means of cardiac catheterization, the aortic valve gradient is determined and the aortic valve area is calculated using the Gorlin equation. Doppler echocardiography allows for a noninvasive gradient assessment. The peak and mean pressure gradients as well as the aortic valve area can be calculated. Echocardiography provides additional information about the severity of the left-ventricular hypertrophy, the heart size, as well as about secondary complications. Doppler echocardiography was performed in 95 patients to determine the peak pressure gradient. This Doppler-derived gradient correlated well with the catheterization-derived invasive gradient. The correlation coefficient was r = 0.81, for the mean gradient r = 0.77, and for the aortic valve area r = 0.87. Based on the classical determination of the severity of aortic stenosis by means of cardiac catheterization, a Doppler-derived mean pressure gradient > 54 mm Hg or a peak pressure gradient > 89 mm Hg and an aortic valve area > 0.7 cm2 are specific for severe aortic stenosis. A mean pressure gradient between 40 and 54 mm Hg or a peak pressure gradient of 67 and 89 mm Hg and an aortic valve area of 0.7 and 1.3 cm2 indicate moderately aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Diagnostic goals in aortic dissection. Value of transthoracic and transesophageal echocardiography].

The combination of different ultrasound techniques like transthoracic, suprasternal, subcostal and transesophageal echocardiography have a high sensitivity and specificity in the diagnosis of aortic dissection. The limitation of this combined ultrasound technique is related to the visualization of the ascending part of the aortic arch which, cause of the interposition of the trachea, can not be visualized completely. The beginning or the end of a dissection in this part of the aorta may be misinterpreted. False negative results are rare. False positive results due to artefacts resulting from reverberations in an ectatic ascending aorta have to be taken into account. The most important diagnostic aims in acute or chronic aortic dissection can be described: 1. confirmation of the diagnosis by visualization of the intima membrane, 2. the differentiation of the true and false lumen depending on visualization of spontaneous echocardiographic contrast thrombus formation, slow or reduced reversed flow, systolic diameter reduction and signs of entry jet into the false lumen, 3. detection of intimal tear, demonstrating communication by two-dimensional or color Doppler echocardiography, 4. determination of the extent of the dissection with classification according to DeBakey type I, II and III or Stanford A and B with differentiation to communicating or non-communicating dissection, antegrade or retrograde dissection limited to the descending aorta or expanding to the ascending aorta, 5. detection of wall motion abnormalities as a sign of preexisting coronary artery disease or myocardial ischemia due to ostium occlusion by an intimal flap, coronary artery rupture or collapse of the true lumen during diastole, 6. detection and grading of aortic insufficiency, 7. detection of side branch involvement by suprasternal, subcostal and abdominal sonography, which will gain the information which side can be chosen for cannulation or catheterization at the femoral artery, 8. detection of pericardial pleural effusion and mediastinal hematoma as a sign of emergency as rupture can occur within minutes. Without surgical intervention have be performed. Based on these informations, surgery can be performed in all acute situations in type A dissection without further investigations. This decision is particularly important in patients with signs of emergency like pericardial or pleural effusion or mediastinal hematoma.

Aortic Dissection↗
PubMed1992

[Intravascular ultrasound in patients with suspected aortic dissection: comparison with transesophageal echocardiography].

Thirteen patients with suspected aortic dissection (two women, 11 men, age 61 +/- 10.8 years) underwent transesophageal echocardiography (TEE), intravascular ultrasound (IVUS), angiography, and in part computed tomography (CT). TEE was performed using 3.5 or 3.75 MHz ultrasound transducers. IVUS examination was done using a 6F 20 MHz "rotational-tip" IVUS catheter (Boston Scientific) advanced over a guiding-wire positioned in the ascending aorta by the "side-saddle" technique. In two patients it was not possible to advance the catheter into the abdominal aorta. Of the remaining 11 patients, eight had aortic dissection (six Typ III, one Typ II, and one Typ I, de Bakey classification). Two patients had aortic aneurysms without dissection and one patient had a perforation of the ascending aorta. TEE, CT, and angiography led to the correct diagnosis in all patients, while IVUS failed to provide precise information within the ascending aorta and the aortic arch. Reasons were the limited scanfield of the 20 MHz transducer and the inability to steer and position the IVUS catheter. Contrary to the limited value in the ascending aorta, IVUS could successfully scan the entire descending aorta, including the dissection membrane and the originating vessels, if the max. diameter was less than 4 cm. No adverse effects occurred. Intravascular ultrasound allows to scan the entire aorta in patients with suspected aortic dissection. The current limitations can be solved only by the introduction of steerable and/or low frequency catheters.

Aged↗
PubMed1992

[The correlation between measurements performed by intravascular echography and quantitative digital angiography in large- and small-caliber arteries].

Intravascular ultrasound is a new promising technique that appears as a very useful complement to standard angiography in the study of atherosclerosis. Specifically, intravascular ultrasound provides by itself, information of great value concerning vessel wall characteristics. Nevertheless, before taking any decision with the results provided by this new technique, we must validate this information with that provided by other more conventional techniques like standard angiography. Accordingly, we have analyzed in 25 patients, 50 images of the abdominal aorta and 77 images of the coronary arteries taken from arterial segments free of atherosclerotic involvement. With the use of a calibrated small grid located over the patient's thorax, we have analyzed "in the same points" the images obtained with intravascular ultrasound and those provided by contrast angiography using a quantitative angiographic analysis. In the abdominal aorta the vessel diameter measured by intravascular ultrasound and angiography was 17.8 +/- 0.39 mm vs 18.6 +/- 0.42 mm (NS), whereas in the coronary arteries it was 2.76 +/- 0.39 mm vs 2.98 +/- 0.37 mm (NS), respectively. The correlation between both techniques was good for both types of arteries (r = 0.93 in the abdominal aorta and r = 0.87 in the coronary arteries). We conclude, that in our experience and with the methodology used, there is a good correlation between the measurements of the vessel diameters obtained by both intravascular ultrasound and digital angiography in arteries of different sizes, being the correlation even better in large arteries.

Adult↗
PubMed1991

Bleomycin-resistance gene derived from the transposon Tn5 confers selective advantage to Escherichia coli K-12.

The plasmid pRAB2 contains a silent operon derived from the transposon Tn5 and carrying the gene neo for neomycin-kanamycin resistance and a truncated ble gene (ble333) for bleomycin resistance. Spontaneous mutants that express the two resistances provide Escherichia coli cells an improved fitness during the phase of decline in the absence of the antibiotics. It is shown that the ble333 gene product is responsible for this better fitness. These results can explain a previously described selective advantage attributed to the presence of Tn5. The improved fitness of bleomycin-resistant bacteria is proposed to relate to DNA repair by the ble gene product. The consequences of the presence of an accessory gene improving fitness are discussed in terms of evolutionary stable strategy of a transposon in populations of E. coli.

Bleomycin↗
PubMed1991

[Results of treatment of paralytic ileus caused by diffuse intra-abdominal metastasis with motilin. A pilot study of 25 patients].

In a pilot-study 25 patients presenting with a paralytic ileus due to diffuse intraabdominal metastases were treated with motilin. There were 16 male (64%) and nine female (36%) patients. Gastric cancer was the most frequent cause (40%), followed by pancreatic (36%), and colorectal (20%) cancer. 36% had received a postoperative chemotherapy before commencing the motilin-scheme. In 92% motilin therapy was started within 48 hours after the diagnosis of paralytic ileus. There were no serious side-effects of motilin therapy. In approximately 80% the pretherapeutic state was improved. Thus, it seems worthwhile to investigate the influence of motilin on paralytic ileus in incurable cancer patients in a prospective controlled trial.

Combined Modality Therapy↗