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Biomedical subjects

M R Mueller

Publications and source records attributed to M R Mueller.

At least 19 recordsLinked to original sources
PubMed2001

Influence of hypotensive and normotensive anesthesia on platelet aggregability and hemostatic markers in orthognathic surgery.

This prospective randomized study investigated the influence of normotensive and hypotensive general anesthesia on platelet aggregability, intraoperative blood loss and parameters of plasmatic coagulation during extensive orthognathic surgery. A total of 30 patients were randomly allocated for either normotensive anesthesia maintained by continuous infusion of propofol and remifentanil (NORMO, n=10) or hypotensive anesthesia, whereby hypotension was induced by increasing the infusion rate of remifentanil (HYPO-R, n=10) or by administration of nitroglycerin (HYPO-N, n=10). Whole blood platelet aggregability was significantly reduced during hypotension compared to normotensive anesthesia (P<.01, HYPO-N and HYPO-R vs. NORMO). Mean arterial blood pressure during hypotension correlated well with adenosinediphosphate- (R=.712, P<.001) and collagen-induced platelet aggregability (R=.685, P<.001). Within hypotensive study groups, postoperative fibrinogen levels were significantly different, whereas intraoperative platelet aggregability, postoperative platelet count, prothrombin time, activated partial thromboplastin time and antithrombin levels were not different. Normotensive anesthesia, however, caused significant decreases in platelet count (-29%), prothrombin time (-24%), fibrinogen (-41%) and antithrombin (-28%) and a significant prolongation in activated partial thromboplastin time (+21%) and thrombin time (+18%). There was a trend to reduced intraoperative blood loss in hypotensive study groups; however, differences were not significant. In conclusion, induced hypotension--independent of substances used for induction of hypotension--reduces intraoperative platelet aggregability, subsequently protecting the coagulation system against subclinical consumption coagulopathy. Induced hypotension-caused platelet dysfunction does not lead to an increased intraoperative blood loss, but quite on the contrary shows a trend to reduced intraoperative blood loss, possibly by preventing platelet-induced subclinical consumption coagulopathy.

Adult↗
PubMed2001

From delegation to specialization: nurses and clinical trial co-ordination.

This paper considers an area of clinical research that has been delegated by physician-researchers to nurses and others in the United States, that of clinical trials co-ordination. It uses interviews with nurse trial co-ordinators to explore the occupational processes by which the boundaries of work enactment and the definition of work have been established by nurses and others. It then discusses the occupational processes that have been established to formalize a role for nurses in clinical research. It raises the question of (and offers speculation on) whether specialization alone will distinguish nursing from other occupational groups engaged in clinical research work.

Attitude of Health Personnel↗
PubMed2000

Early detection of preeclampsia by determination of platelet aggregability.

Preeclampsia is still a leading cause of maternal and fetal morbidity and mortality. There is evidence for the involvement of platelets. Therefore, we investigated the suitability of corrected whole blood impedance aggregometry as an early predictor of preeclampsia in 71 consecutive, high-risk pregnancies. According to the occurrence of preeclampsia, defined postpartum by an independent investigator, and the stage of pregnancy (early and late, cutoff: 25 weeks of gestation), four study groups were defined. Platelet aggregation data were corrected for the influence of hematocrit and platelet count by a special purpose software package. Women developing preeclampsia showed significantly higher platelet aggregation response compared to controls in early and late pregnancy. In early pregnancy, all women developing preeclampsia had aggregation responses to collagen higher than the highest responses among the controls. Hence, this test had a 100% positive predictive value of subsequent preeclampsia. Despite being significantly increased, platelet aggregability was of minor predictive value in late pregnancy. We conclude that preeclampsia is accompanied by exaggerated platelet aggregability, particularly perceptible early in the course of pregnancy. We propose collagen-induced whole blood platelet aggregation with correction for the influence of hematocrit and platelet count for early detection of preeclampsia.

Adenosine Diphosphate↗
PubMed2000

Bronchoplastic procedures in malignant and nonmalignant disease: multivariable analysis of 144 cases.

OBJECTIVES: We sought to analyze the experience with bronchoplastic procedures over a 7-year period and to determine putative prognostic factors for survival. METHODS: From 1991 to 1997, 144 bronchoplastic procedures were performed for non-small cell lung cancer (n = 123), small cell lung cancer (n = 5), carcinoid tumor (n = 10), and metastases of extrathoracic malignant tumors (n = 6). There were 111 sleeve lobectomies, 17 bilobectomies, 4 lobectomies with carinal resection, 8 sleeve pneumonectomies, and 4 bronchotomies without parenchymal resection. Multivariable analysis included risk factors, such as age, sex, type of bronchoplastic procedure (bronchotomy, lobectomy, bilobectomy, or pneumonectomy), additional angioplasty, TNM staging, histology, radicality of resection, respiratory risk (forced expiratory volume in 1 second, percent predicted < 60), cardiovascular risk, and adjuvant therapy. RESULTS: Overall 1- and 3-year survival was 72% and 52%, respectively. The overall 30-day mortality was 8.3% (5.4% for single sleeve lobectomies). Multivariable analysis demonstrated 4 risk factors for survival. High tumor stage, type of bronchoplastic procedure, impaired lung function, and presence of cardiovascular risk were associated with a poor outcome. Univariate analysis showed reduced survival in patients with sleeve pneumonectomies (1-year survival, 25%). CONCLUSIONS: Bronchoplastic procedures for central tumors and sleeve pneumonectomies are associated with poor survival. Careful selection of these patients, as well as of patients with impaired lung function and cardiovascular risk factors, is mandatory.

Adult↗
PubMed2000

[Complete resection of isolated lung metastasis from breast carcinoma results in a strong increase in survival].

BACKGROUND: Surgical treatment of pulmonary resection for metastatic disease has been proven a valuable therapeutic concept for a variety of neoplasms. Concerning breast cancer, at least 25% of patients develop distant metastases. In spite of increasingly sophisticated palliative therapies, the survival of these patients did not appear significantly prolonged during the last 25 years (19-32 months following diagnosis) and about 95% die from metastatic disease. METHODS: Between 1977 and 1997, three epidemiological comparable groups out of a total of 125 patients of our clinic were treated for isolated pulmonary metastasis following breast cancer. Complete data from 96 patients were retrospectively analyzed following stratification to three groups according their surgical therapy: C, complete resection, 28 patients; I, incomplete resection, 34 patients; N, no resection, 34 patients. RESULTS: Comparison of the three therapy methods concerning stage, histology and receptor levels of the primary tumor, number of metastases and the disease free interval (DFI), as well as adjuvant therapy modalities yielded no significant differences. Mean survival of group C was with 79 months (5-years-survival 80%, 10-years-survival 60%) significantly better compared to groups I and N (p < 0.00002). Mean survival of group I and N was not significantly different (15.5 and 9 months respectively). The DFI had no impact on the survival of group C, but showed a high correlation with the survival of group N (R2 = 0.81). CONCLUSIONS: Routine chest X-ray is necessary in the follow-up of breast cancer patients and if coin lesions occur, thoracic surgeon should be contacted.

Aged↗
PubMed1999

Changes of platelet surface antigens in patients suffering from abdominal septic shock.

Sepsis and related syndromes account for a high morbidity and mortality caused by the development of multiorgan failure. Pathogenesis of sepsis is complex, involving humoral as well as cellular factors. Since the role of platelets is still undefined in this concern, we investigated CD63, CD62P, CD36, and CD31 expression on platelets of patients in septic shock (n = 18) using a flow cytometric assay in whole blood. Samples were drawn within 24 hours of onset. We found thrombocytopenia accompanied by a significantly higher expression of CD63, CD62P, and CD31 and a significant downregulation of CD36 in comparison to healthy volunteers (n = 18). Changes in CD63 and CD62P expression indicates platelet activation. Because CD62P, CD36, and CD31 mediate interaction of platelets with leukocytes, subendothelial matrix and probably endothelial cells as well as platelet adhesion/aggregation, our findings suggest an involvement of platelets in leukocyte/endothelial cell interaction in septic shock. We suspect that thrombocytopenia is not due to bone marrow depression, but rather is due to consumption of highly activated platelets in the microcirculation. We feel that our observations may offer a rationale for potentially beneficial effects of antiplatelet therapy in sepsis; however, further studies have to evaluate its beneficial impact as well as its potential risk for bleeding complications.

Antigens, CD↗
PubMed1998

Physician administrators and the reorganization of federally sponsored treatment research for AIDS.

Scholars of modern medicine are concerned with the implications of the movement of physicians into "elite" administrative positions in medical practice settings. To date, empirical studies of physician administrators have focused on their response to disputes that arise between medical and non-medical groups. This paper uses the case of federally funded treatment research for AIDS in the United States to explore the actions of physician administrators and the implications of those actions, in resolving intra-professional conflict. The findings suggest that the actions of elite physician administrators sometimes serve to enhance the fortunes of medical professionals. The findings further suggest that the actions of elite physician administrators sometimes serve to reproduce and affirm professional status distinctions that exist within the broader context of health delivery.

Academies and Institutes↗
PubMed1997

Survival after surgical treatment of recurrent pulmonary metastases.

OBJECTIVE: Resection of lung metastases is a generally accepted therapeutic strategy today. This retrospective study was performed in order to estimate the value of an aggressive surgical approach in recurrent metastatic disease of the lung. METHODS: The survival rates of 42 patients undergoing repeated resectional treatment for recurrent lung metastases (group A) were compared to the outcome of a total of 288 patients after a single surgical intervention for lung metastases (group B). Survival rates and the relative effects of the various prognostic factors were calculated according to Kaplan-Maier and Mantel Cox or Wilcoxon test. Histology of the primary tumors in group A consisted of 18 carcinomas, 22 sarcomas and two melanomas, in group B the distribution was 64% carcinoma, 27% sarcoma and 9% melanoma. The mean follow-up period was 88.5 months for group A and 27 months for group B. RESULTS: The overall survival rate for group A was 48% at 5 years and 30% at 10 years, the survival rate for group B was 34% at 5 years. CONCLUSION: Long-term survival rates superior to those after single resectional treatment for lung metastases encourage an aggressive surgical approach for this disease.

Adolescent↗
PubMed1997

Variable platelet response to low-dose ASA and the risk of limb deterioration in patients submitted to peripheral arterial angioplasty.

A group of 100 patients with intermittent claudication (70 male, 30 female), treated with I00 mg ASA per day, were followed over 18 months after elective percutaneous balloon angioplasty. Platelet function was monitored over a period of 12 months by corrected whole blood aggregometry (CWBA). Upon stimulation by arachidonic acid (AA), adenosine diphosphate (ADP) and collagen, CWBA-results were obtained by an electronic acquisition and evaluation system correcting for hematocrit and platelet count of the blood sample. All patients showed a completely inhibited platelet response to AA stimulation. Comparison of the CWBA-results with clinical parameters revealed that reocclusions at the site of angioplasty occurred exclusively in male patients for which CWBA failed to prove an inhibition of aggregation upon both agonists, ADP and collagen, and for these patients the risk of complication is at least 87% higher (p = 0.0093). Only 40% of male patients show the expected effect of ASA on in vitro platelet aggregation at any given point in time and CWBA is capable of predicting those male patients which are at an elevated risk of reocclusion following peripheral angioplasty.

Administration, Oral↗
PubMed1996

Influence of UW solution on in vitro platelet aggregability.

Bleeding problems in orthotopic liver transplantation (OLT), starting immediately after reperfusion of the graft, are complicating the outcome of transplantation. Platelets may be involved in this situation, but there is still a lack of information about the influence of UW solution on platelet function. We evaluated the effect of UW solution on in vitro platelet aggregability in healthy volunteers using whole blood electrical aggregometry and concluded, that UW solution causes impaired platelet aggregability and may contribute to bleeding problems during OLT. The mechanism of impairment remains unclear, since central pathways as well as membrane receptors seem to be involved. Furthermore, our data support the necessity of extended flushing of the liver graft after reperfusion.

Adenosine↗
PubMed1994

Carcinogen-specific mutations in the p53 tumor suppressor gene in lung cancer.

Mutations of the p53 tumor suppressor gene, whose encoded protein is one of the chief regulators of the cell cycle, are proving to be the most common genetic alteration in human cancer. Point mutations have been detected in numerous human solid tumors. The types of point mutations in the p53 gene vary considerably in different kinds of human cancers, suggesting that specific etiologic agents are responsible for typical kinds and sites of mutations in the p53 gene. This study reports the detection of two unusual p53 mutations in a series of patients with lung cancer. The first case showed a one-base pair deletion at the end of exon 8, which is rarely affected by mutations, leading to a frameshift involving the following intron 8, exon 9, and intron 9. The second case exhibited two point mutations in codon 273, both either localized in the same codon on one allele or each mutation localized on a different allele in codon 273. Interestingly, the two mutations can be attributed to different mechanisms of base substitution. This is the first report of this kind. Because of evidence that the nature and site of p53 mutations reflect not only the mutagens involved in tumorigenesis but also the capacity for malignant transformation, the characterization of mutations of the p53 gene may provide a basis for assessing further risk factors, as well as for estimating prognosis in patients with lung cancer.

Adenocarcinoma↗
PubMed1993

Clinical experience with minimally invasive thoracic surgery.

From October 1991 to June 1992 video-endoscopic lung surgery was applied in a total of 109 patients. In the first case a pulmonary cyst measuring 15 x 18 cm was resected. In 21 patients lung nodules were exstirpated by means of wedge resection. Moreover, metastasectomies, open lung biopsies, parietal pleurectomies, resections of bullae, and decortications, as well as 3 lower-lobe lobectomies were performed using video-endoscopic procedures. Closure of lung parenchyma was carried out using the 3 cm Endo-GIA stapler (Autosuture). In none of the patients were we forced to enlarge the intervention to a thoracotomy because of technical problems. Indications, operative technique and results are presented. This new technique offers all the known advantages of minimally invasive surgery to patients requiring thoracic surgery.

Anesthesia, General↗
PubMed1993

In vitro hematological testing of rotary blood pumps: remarks on standardization and data interpretation.

Pump test procedures using blood will have to meet several standards not only to obtain reliable results in vitro but also to allow comparison of results of different investigators. This article reviews some of the issues that should be considered in pump testing, especially referring to the discussions held at the International Workshops on Rotary Blood Pumps in 1988 and 1991. The test loop itself should meet some requirements such as constant physiological temperature, standardized circulating volume, control of pressure and flow, and exact definition of the blood-contacting surface. Specifications have to be made concerning the test fluid blood, including sampling technique, anticoagulation, blood gases, pH, and glucose level. Only fresh blood should be used. Heparin is recommended for anticoagulation because it will be used also in vivo. Different procedures for cleaning and rinsing of plastic materials for reuse are mentioned. Bacterial overgrowth, which can lead to extreme oxygen consumption and acidosis, may be avoided through addition of antibiotics (e.g., gentamicin). To be able to compare data of the different working groups, a new modified index of hemolysis (MIH) has been defined.

Animals↗
PubMed1990

Pulmonary surfactant in bronchoalveolar lavage after canine lung transplantation: effect of L-carnitine application.

Pulmonary surfactant during lung transplantation was investigated in the control group of a canine single lung transplantation model by measuring dipalmitoyl-phosphatidylcholine, the main phosphocholine fraction of surfactant in bronchoalveolar lavage. In a second group of dogs, L-carnitine, an essential cofactor for transfer of long-chain fatty acids into the mitochondria, was applied. Organ function after pulmonary artery flushing with modified Euro-Collins solution and hypothermic storage for 4 hours was adequate in both groups, with significantly higher arterial oxygen pressure levels in the L-carnitine group after 12 (p less than 0.05) and 24 (p less than 0.025) hours, respectively. In the control group, a reduction of the dipalmitoyl-phosphotidylcholine portion on total phosphotidylcholines was observed 4 and 12 hours after transplantation of the left lung (p less than 0.005 and p less than 0.01, respectively, both specified by Student's t test for dependent data, not significant by Bonferroni correction). In the simultaneously stored right lungs, a constant fall of the dipalmitoyl-phosphotidylcholine portion was demonstrated. In the L-carnitine group, significantly higher dipalmitoyl-phosphotidylcholine levels were observed in the transplanted left lungs after 4 hours (p less than 0.01) and in the continuously stored right lungs after 24 hours (p less than 0.005), when compared with the control group. These results suggest that dipalmitoyl-phosphotidylcholine portion on total phosphotidylcholine decreases parallel to the extent of the ischemic damage. Furthermore, the application of L-carnitine improved pulmonary function after transplantation, possibly by reducing the impairing effect of ischemia on alveolar type II cell metabolism and thereby on pulmonary surfactant system.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1988

Connective-tissue disease following breast augmentation: a preliminary test of the human adjuvant disease hypothesis.

It has been proposed that scleroderma in particular or connective-tissue diseases in general may be caused by exposure to silicone-containing materials used for breast augmentation. We performed a historical cohort study to estimate the point prevalence of this potential complication sometimes referred to as "human adjuvant disease." Three-hundred and seventy-eight patients who underwent augmentation mammaplasty with silicone-containing envelope-type prostheses from 1970 through 1981 were surveyed. Regional musculoskeletal syndromes, fibrositis, or osteoarthritis occurred in a third (38 of 125) of our responders. No patient developed an inflammatory systemic rheumatic disease during the period of observation (mean 6.8 years for the 125 subjects). Using calculations based on risk for development of rheumatic disease, it does not appear likely that augmentation mammaplasty is a significant or major inducer of inflammatory connective-tissue diseases in general. However, the number of patients surveyed was small, and our results must be considered preliminary. We could not exclude a specific risk for the development of scleroderma.

Adult↗