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Biomedical subjects

L Weber

Publications and source records attributed to L Weber.

At least 163 records · Page 9Linked to original sources
PubMed1985

Spectrum of acute hemodynamic effects of nifedipine in severe congestive heart failure.

The acute hemodynamic effects of 20 to 50 mg of orally administered nifedipine were evaluated in 31 patients with severe chronic congestive heart failure (CHF) and the results were analyzed according to the response of the cardiac index (CI). Although the group mean value of CI increased significantly after nifedipine treatment (from 2.1 +/- 0.5 to 2.4 +/- 0.8 liters/min/m2, p less than 0.001), the individual response was variable. Twenty of the patients had 15% or greater increase in CI (group A) and 11 patients had less than a 15% increase or a decrease in CI (group B). Marked differences were also noted in the effects of nifedipine on other hemodynamic variables. Stroke volume increased 29 +/- 14% in group A and decreased 11 +/- 18% in group B (p less than 0.001). Systemic vascular resistance decreased 34 +/- 11% in group A (p less than 0.001) and increased slightly, 2 +/- 28%, in group B. Left ventricular (LV) stroke work index increased 11 +/- 19% in group A (p less than 0.001) and decreased markedly in Group B (21 +/- 20%). Six group B patients had a substantial worsening (20% or more) of one or more hemodynamic measurements, including CI, stroke volume index, LV stroke work index and mean pulmonary artery wedge pressure. A comparison of control hemodynamic values at rest, LV ejection fraction, associated coronary artery disease, nifedipine dose, and concomitant diuretic therapy revealed no significant differences between the 2 groups. This study confirms, in a large group of patients with severe CHF, the variable hemodynamic effects of nifedipine therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1985

Effect of diltiazem on renal clearance and serum concentration of digoxin in patients with cardiac disease.

The effect of diltiazem on digoxin serum concentration was evaluated in 9 patients who had been treated chronically for heart disease with digoxin, 0.25 mg/day. The indications for digoxin therapy were arrhythmias in 5 patients and mild heart failure in the other 4. Renal digoxin clearance was also evaluated in 8 of these patients. Serum digoxin concentration was measured at control, 7 +/- 2 days after initiation of 120 mg/day of diltiazem and 11 +/- 5 days after increasing the dose of diltiazem to 240 mg/day. Serum digoxin concentration was 0.9 +/- 0.4 ng/ml at control, 0.8 +/- 0.4 ng/ml with 120 mg/day of diltiazem, and 0.8 +/- 0.3 ng/ml during therapy with 240 mg/day. The differences between these values were not significant. Renal digoxin clearance also did not show a significant change after diltiazem therapy (44 +/- 15 ml/min before diltiazem and 46 +/- 13 ml/min with 240 mg/day of diltiazem). This study shows no effect of diltiazem in doses of 120 to 240 mg/day on serum digoxin concentration or renal digoxin clearance in patients who are treated chronically for heart disease with digoxin. In this dose range, diltiazem has advantages over verapamil, which markedly elevates digoxin levels.

Adult↗
PubMed1985

Dermatofibrosarcoma protuberans: altered collagen metabolism in cell culture.

Dermatofibrosarcoma protuberans is a low-grade malignant tumor that grows invasively but rarely forms metastases. Its origin is still controversial. We characterized the synthesis of collagen in detail in cells which were obtained from dermatofibrosarcoma protuberans tumors by enzymatic tissue disintegration. Similar to fibroblasts, all tumor cell strains produced considerable amounts of collagen. However, the rate was reduced compared to normal skin fibroblasts. Cells grown from the tumors synthesized type I collagen, but no type II could be detected. After serial passaging the cultures started to produce type III collagen, which is probably due to a slow overgrowth by normal fibroblasts.

Cells, Cultured↗
PubMed1985

Isometric exercise in patients with chronic advanced heart failure: hemodynamic and neurohumoral evaluation.

We evaluated the hemodynamic effects of isometric exercise in 53 patients with congestive heart failure (CHF) and compared them with those found in 10 normal subjects. In both groups, isometric exercise increased heart rate and blood pressure. Systemic resistance increased in patients with CHF (1862 +/- 520 vs 2126 +/- 642 dyne-sec-cm-5; p less than .001) but not in normal subjects (1359 +/- 268 vs 1380 +/- 252 dyne-sec-cm-5). Cardiac index and stroke volume index increased mildly but not significantly in the normal subjects (2.8 +/- 0.5 vs 3.1 +/- 0.7 liters/min/m2 and 46 +/- 8 vs 47 +/- 7 ml/m2) and showed a significant fall in the patients with CHF (2.1 +/- 0.6 to 1.9 +/- 0.6 liters/min/m2, p less than .01 and 23 +/- 7 vs 20 +/- 7 ml/m2, p less than .01). Mean pulmonary arterial wedge pressure increased in patients with CHF from 26 +/- 7 to 30 +/- 8 mm Hg (p less than .001). Although no significant change was found in mean value for stroke work index (21 +/- 9 vs 20 +/- 9 g-m/m2), the individual changes were variable, with marked decrease (greater than 15%) in 17 of the patients. This hemodynamic deterioration could not be predicted from resting hemodynamics, left ventricular ejection fraction, or functional classification. Isometric exercise resulted in no significant change in circulatory catecholamine levels or plasma renin concentration in our 10 normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

[Familial, structural aberration of the Y chromosome with fertility disorders].

Cytogenetic studies on a patient with Klinefelter's syndrome revealed an inherited, structural aberration of the Y-chromosome which has not been described before. The aberrant Y-chromosome was characterized by eight different banding methods. The value of individual staining techniques in studies on Y-heterochromatin aberrations is emphasized. Analysis of the cytogenetic studies (banding methods, restriction endonuclease of DNA, and measurement of the length of the Y-chromosome) permits an interpretation to be made on how the aberrant Y-chromosome originated. The functions of the Y-chromosome are discussed. The decrease in fertility (cryptozoospermia) in the two brothers with the same aberrant Y-chromosome was striking.

Adolescent↗
PubMed1984

Differences in hemodynamic response to vasodilation due to calcium channel antagonism with nifedipine and direct-acting agonism with hydralazine in chronic refractory congestive heart failure.

The hemodynamic response to a similar reduction of systemic vascular resistance after nifedipine and hydralazine administration was compared in a randomized crossover protocol in patients with severe chronic congestive heart failure (CHF). All 15 patients showed a 25% or greater reduction in vascular resistance with intravenous hydralazine (5 to 30 mg) and 11 patients showed a similar response with oral nifedipine (20 to 50 mg). In the latter 11 patients, despite similar reductions in systemic vascular resistance (35 +/- 2% with nifedipine and 36 +/- 4% with hydralazine, difference not significant), nifedipine resulted in a smaller increase in stroke volume index (from 23 +/- 2 to 30 +/- 2 ml/m2 and from 24 +/- 2 to 34 +/- 2 ml/m2 with hydralazine, p less than 0.05), cardiac index (from 2.0 +/- 0.1 to 2.6 +/- 0.2 liters/min/m2 with nifedipine and from 2.0 +/- 0.1 to 2.8 +/- 0.2 liters/min/m2 with hydralazine, p less than 0.05) and stroke work index (from 25 +/- 3 to 27 +/- 3 gm/m2 with nifedipine and from 26 +/- 2 to 32 +/- 2 gm/m2 with hydralazine, p less than 0.05). The decrease in blood pressure after nifedipine was slightly but not significantly larger than that with hydralazine (13 +/- 3% vs 8 +/- 2%). The changes in right atrial pressure, pulmonary artery wedge pressure and pulmonary vascular resistance were similar. The 4 patients who did not reduce their systemic vascular resistance by at least 25% with nifedipine had a worsening of their hemodynamic state as evidenced by 1 or more of the following findings: elevation of vascular resistance, decrease in cardiac index and increase in pulmonary artery wedge pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Favorable effects of hydralazine on the hemodynamic response to isometric exercise in chronic severe aortic regurgitation.

The hemodynamic effects of isometric exercise and the response to hydralazine therapy were evaluated in 11 patients with chronic, severe aortic regurgitation (AR). Isometric exercise produced a significant increase in heart rate (from 78 +/- 11 to 93 +/- 19 beats/min [mean +/- standard deviation], p less than 0.05), mean blood pressure (from 83 +/- 8 to 104 +/- 20 mm Hg, p less than 0.05), mean right atrial pressure (from 3 +/- 2 to 7 +/- 5 mm Hg, p less than 0.05) and mean pulmonary artery wedge pressure (from 12 +/- 7 to 18 +/- 10 mm Hg, p less than 0.05). Small and insignificant changes were seen in cardiac index (from 3.4 +/- 0.8 to 3.9 +/- 1.0 liters/min/m2), systemic vascular resistance (from 1,097 +/- 257 to 1,171 +/- 284 dynes s cm-5), pulmonary vascular resistance (from 120 +/- 76 to 130 +/- 89 dynes s cm-5) and stroke volume index (from 44 +/- 10 to 43 +/- 12 ml/m2). After oral hydralazine administration (100 to 300 mg), hemodynamic values during isometric exercise were: Heart rate increased further, to 105 +/- 14 beats/min (p less than 0.05), mean blood pressure was 102 +/- 16 mm Hg (difference not significant [NS]) cardiac index increased markedly, to 5.2 +/- 1.4 liters/min/m2 (p less than 0.05), stroke volume index increased to 49 +/- 12 ml/m2 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Comparison of hemodynamic responses to nifedipine and nitroprusside in severe chronic congestive heart failure.

The hemodynamic effects of 20 to 40 mg of oral nifedipine were compared with those of intravenous nitroprusside in 11 patients with severe chronic congestive heart failure (CHF). In each patient, both drugs were administered to produce similar reduction of systemic vascular resistance (SVR) (29 +/- 13% with nifedipine and 29 +/- 12% with nitroprusside, difference not significant [NS]). At this comparable decrease in systemic vascular resistance, significant differences in hemodynamic responses to both drugs were noted: Nifedipine caused a smaller increase in cardiac index (20 +/- 20% vs 40 +/- 24%, p less than 0.02) and a larger decrease in mean blood pressure than nitroprusside (16 +/- 9% vs 8 +/- 10%, p less than 0.05). In addition, nifedipine produced a smaller decrease in mean pulmonary artery wedge pressure (13 +/- 24% vs 36 +/- 21%, p less than 0.001) and pulmonary vascular resistance than nitroprusside (6 +/- 42% vs 26 +/- 46%, NS). Mean right atrial pressure decreased with nitroprusside, from 10 +/- 7 to 5 +/- 3 mm Hg (p less than 0.05), but not with nifedipine (10 +/- 7 mm Hg before and after nifedipine administration, NS). Left ventricular stroke work index increased with nitroprusside (20 +/- 8 to 27 +/- 9 g-m/m2, p less than 0.05), but did not change with nifedipine (21 +/- 9 vs 21 +/- 10 g-m/m2, NS). These data show that nifedipine has an arteriolar dilatatory action in patients with CHF. However, compared with nitroprusside, nifedipine had a significantly larger hypotensive effect and had a lesser effect on right and left ventricular filling pressure, cardiac output and left ventricular function.

Administration, Oral↗
PubMed1984

Renal hemodynamic effects of vasodilation with nifedipine and hydralazine in patients with heart failure.

The central and renal hemodynamic effects of nifedipine were evaluated in nine patients with severe chronic congestive heart failure. Oral nifedipine (34 +/- 22 mg, mean +/- standard deviation) was associated with a decrease in systemic vascular resistance from 1,748 +/- 436 to 1,321 +/- 302 dynes . s . cm-5 (p less than 0.001) and mean arterial blood pressure from 96 +/- 11 to 87 +/- 6 mm Hg (p less than 0.05) and with an increase in cardiac output from 4.2 +/- 1.1 to 4.9 +/- 1.2 liters/min (p less than 0.001). Although renal vascular resistance decreased from 11,988 +/- 2,256 to 10,286 +/- 3,011 dynes . s . cm-5 (p less than 0.05), no significant change was seen in renal blood flow (599 +/- 120 to 640 +/- 162 ml/min), glomerular filtration rate (62 +/- 18 to 62 +/- 17 ml/min), filtration fraction (18 +/- 5 to 17 +/- 6%), the ratio of renal/systemic vascular resistance (7.0 +/- 1.0 to 7.9 +/- 1.8) and the ratio of renal blood flow/cardiac output (0.15 +/- 0.02 to 0.13 +/- 0.03). Intravenous hydralazine (10 +/- 5 mg), given to eight of the patients in a randomized crossover design, resulted in a larger increase in cardiac output than did nifedipine (38 +/- 7 versus 19 +/- 10%, p less than 0.001) and in an increase in total renal blood flow from 570 +/- 152 to 645 +/- 174 ml/min (p less than 0.001). Renal vascular resistance decreased from 12,080 +/- 2,934 to 10,153 +/- 2,372 dynes . s . cm-5 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Collagen type distribution and macromolecular organization of connective tissue in different layers of human skin.

Human skin is composed of several layers which are characterized by a specific macromolecular organization of connective tissue. Three approaches were used to quantify the collagen types present in each of the different layers: biochemical analysis of authentic tissue, metabolic labeling of organ cultures, and metabolic labeling of fibroblast monolayers. We obtained reproducible evidence for a somewhat higher ratio of type III/type I collagen synthesis in the papillary dermis and the subcutaneous fat compared to the reticular layer. Constant amounts of alpha 1 (I) trimers and type V collagen were found in all layers. The degree of hydroxylation of lysine in either type I or type III collagen was the same in any layer of the skin.

Adipose Tissue↗
PubMed1984

Basement membrane components outline the tumour islands in cylindroma.

The main histological feature of cylindroma is the deposition of sheaths of a 'hyalinized' material contiguous to the tumour cell clusters. Although ultrastructural studies of this material have revealed a basement membrane-like structure, its exact nature has remained unclear. Using immuno-staining with affinity-purified antibodies directed against distinct basement membrane components, we have shown that type IV collagen and laminin are major constituents of this zone. In addition, cell culture studies indicated that both proteins are synthesized by the tumour cells. The immunohistological data make it clear that the tumour matrix between the tumour cell islands is composed not only of basement membrane components, but also is composed of other connective tissue constituents, i.e. type I and III collagen and fibronectin.

Basement Membrane↗
PubMed1984

[Basement membranes--structure, function, pathology].

Basement membranes are extracellular structures with a heterogeneous molecular composition. Several components have been identified and could be localized in specific morphological structures. Type IV collagen is found in the lamina densa, whereas laminin is the major component of the lamina lucida. Small amounts of heparan sulfate proteoglycan are also present in the lamina lucida. In some basement membranes, fibronectin and another glycoprotein, nidogen, could be identified. Epidermal basement membranes contain, in addition, the bullous pemphigoid antigen. Basement membranes are involved in several diseases and play an important part in tumor progression. Antibodies against distinct components of basement membranes have been shown to be useful as diagnostic tools in bullous disorders (e.g., epidermolysis bullosa) and for identifying the extracellular matrix of skin tumors (e.g., neurofibroma, cylindroma, granular cell myoblastoma).

Basement Membrane↗
PubMed1984

[Pemphigus herpetiformis].

Clinically, pemphigus herpetiformis closely resembles dermatitis herpetiformis Duhring. Histologically, however, it is characterized by acantholysis and eosinophilic spongiosis. Immunohistology revealing IgG bound in the intercellular space of the epidermis enables the correct diagnosis.

Aged↗
PubMed1983

Acute hemodynamic effect of oral nifedipine in severe chronic congestive heart failure.

The temporal hemodynamic effects of oral nifedipine after a single dose of 20 to 40 mg were evaluated in 11 patients with severe chronic congestive heart failure (left ventricular ejection fraction 0.22 +/- 0.7 [mean +/- standard deviation]). Nifedipine significantly reduced systemic vascular resistance, from 1,850 +/- 493 to 1,315 +/- 398 dynes s cm-5 at 1 hour (29%), to 1,410 +/- 246 at 3 hours and to 1,523 +/- 286 at 6 hours (p less than 0.05). Cardiac index increased 21%, from 2.07 +/- 0.46 to 2.51 +/- 0.83 liters/min/m2 at 1 hour, to 2.38 +/- 0.53 liters/min/m2 at 3 hours (p less than 0.05) and to 2.24 +/- 0.41 liters/min/m2 at 6 hours. The group response of stroke volume to nifedipine was smaller. A peak increase of 17% was seen 3 hours after initiation of therapy (22.6 +/- 7.2 versus 25.5 +/- 6.1 ml/m2). This difference did not reach statistical significance. Mean blood pressure declined significantly, from 94 +/- 20 to 80 +/- 13 mm Hg at 1 hour, to 83 +/- 15 mm Hg at 3 hours and to 86 +/- 17 mm Hg at 6 hours (p less than 0.05) and was associated with no significant change in heart rate. The marked decrease in blood pressure resulted in a decrease in rate-pressure product from 12,272 +/- 4,230 to 10,500 +/- 2,074 mm Hg/min at 1 hour, to 10,374 +/- 2,735 mm Hg/min at 3 hours and to 11,047 +/- 3,813 mm Hg/min at 6 hours (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Exercise two-dimensional echocardiography: a technique for improving ultrasound images during exercise stress.

A system of exercise stress echocardiography was developed in which, during exercise on a bicycle ergometer in a semirecumbent position, the echocardiographic transducer is held by a special device which maintains a relatively constant position between the transducer and the heart. The system was evaluated in 21 healthy subjects and technically satisfactory studies were obtained in 20. In these, the resolution and relative position of the cardiac image remained stable throughout exercise. Blood pressure and heart rate increased appropriately with our protocol with supine exercise; 95% of the subjects reached 90% of their predicted maximum heart rate for age. Ejection fraction measured by echocardiography increased from 54 +/- 1% to 70 +/- 1%. It is concluded that the use of our transducer-holding device in subjects performing exercise in the supine position significantly improves ultrasonic image quality and should enhance the clinical usefulness of exercise stress echocardiography.

Adult↗
PubMed1983

The chemiluminescent response of bovine polymorphonuclear leucocytes isolated from milk and blood.

Polymorphonuclear leucocytes (PMN) were isolated from milk and blood of healthy cows, and the generation of reactive oxygen by the two cell populations was compared by measuring chemiluminescence (CL) after stimulation with zymosan. The ratio of milk to blood PMN CL was relatively constant in a given animal, but varied widely between different cows, ranging from 0.3 to 1.3. The relative contributions of various oxygen species to CL was studied by measuring quenching using different oxygen scavengers. While the relative contributions of H202, -02 and '02 seemed to be similar in both milk and blood PMN, the OH. radical was clearly more prominent in PMN isolated from milk than from blood. In addition, blood PMN CL was more dependent on the presence of glucose in the reaction medium than milk PMN CL. Furthermore, the CL response to phorbol myristate acetate, to the Ca ionophore A23187 and to Sendai virus was different in the two cell types. The results suggest that CL generation in milk PMN differs from that in blood PMN in quantitative as well as qualitative aspects.

Animals↗