Biomedical subjects

M Wolf

Publications and source records attributed to M Wolf.

At least 91 records · Page 5Linked to original sources

PubMed2001

[Malformation of a bronchial artery with shunt into the pulmonary vascular bed - a rare cause of massive haemoptysis].

We present the case of an otherwise healthy 41-year-old woman, who was admitted after having expectorated bright red blood. While the chest roentgenogram was found to be normal, fiberoptic bronchoscopy revealed mild active bleeding originating from the apicoposterior segmental bronchus of the left upper lobe, which exacerbated during the examination. The bleeding was contained through blockade of the upper lobe bronchus by means of a double-lumen endotracheal tube. After the patient had been referred to our department, we performed a resection of the superior segmental group of the left upper lobe. The histopathological examination of the specimen revealed a malformation of the bronchial artery with an abnormal communication to a branch of the pulmonary artery. The malformation was located in close proximity to the apicoposterior segmental bronchus. Whereas arteriovenous malformations with a pulmonary artery branch as feeding vessel have been described in more than 500 cases and primarily affect patients with hereditary hemorrhagic teleangiectasia (HHT, Rendu-Osler-Weber disease), the 23 reported cases of malformations supplied by a branch of the bronchial artery show no evidence of heredity. Furthermore, clinical appearence and localisation show characteristical differences between arteriovenous malformations with pulmonary arterial supply and malformations arising from a bronchial arterial source. Therefore, it seems appropriate to make a clear-cut distinction between these two patterns of vascular malformation of the lung.

Adult↗

PubMed2001

Laryngotracheal anastomosis: primary and revised procedures.

OBJECTIVES: Acquired upper airway stenosis is usually associated with a complex of pathological conditions at the high tracheal and the subglottic levels. Reported reconstructive techniques include widening by incorporation of grafts, segmental resection, and anastomosis or combined procedures. The management of recurrent stenosis after reconstructive surgery is a major challenge and has rarely been discussed in the literature. The purposes of the present study are to compare the clinical course of primary versus revised reconstructive procedures and to analyze the effect of age, diabetes, chronic lung disease, grading of stenosis, extent of resection, and revised procedures on the operative rate of success. STUDY DESIGN: A cohort study in a tertiary referral medical center. METHODS: The clinical course of 23 consecutive patients undergoing laryngotracheal anastomosis was studied comparing a group of 13 primary with 10 revision procedures. Seventeen patients underwent cricotracheal and six patients thyrotracheal anastomoses. All patients but one were tracheotomized before the definitive reconstructive procedure. Suprahyoid release was routinely performed except for two cases, and only one patient required sternotomy. The Wilcoxon test was used to examine the relationship between preoperative clinical parameters and the postoperative success (i.e., airway patency). RESULTS: Twenty-two of 23 patients (95.6%) had successful decannulation. Four patients required a revision procedure because of repeat stenosis at the site of the anastomosis (2) or distal tracheal malacia (2). Residual airway stenosis of less than 50% was noted in six patients, although only three complained of dyspnea during daily-activity exertion. There was no associated mortality. Complications included subcutaneous emphysema (4), granulation tissue formation (3), pneumonia (2), cardiac arrhythmia (2), and one each of pneumomediastinum, neck hematoma, and urosepsis. Protracted aspirations were noted in one patient who had revision surgery. Age was the only parameter that correlated with postoperative airway patency (P <.07), whereas the presence of chronic obstructive lung disease and diabetes, grade of stenosis, type of surgery, and revision surgery were found to be insignificant. CONCLUSIONS: The clinical course of laryngotracheal anastomosis in primary and revised procedures was similar in our group of patients. The operation can be performed safely, with an expected high rate of success and acceptable morbidity.

Anastomosis, Surgical↗

PubMed2001

Estimation of cerebral oxygenation and hemodynamics in cerebral vasospasm using indocyaningreen dye dilution and near infrared spectroscopy: a case report.

Changes in cerebral hemodynamics and oxygenation patterns in cerebral vasospasm might be underestimated if transcranial doppler sonography and angiography findings are considered singularly. This report describes preliminary findings in further development of a noninvasive method that estimates regional cerebral oxygenation and perfusion. A 50-year-old patient suffering from cerebral vasospasm after subarachnoid hemorrhage before and after superselective papaverine infusion was examined. Measurements were taken by using a technique combining indocyaningreen dye dilution and near infrared spectroscopy. Our first results suggest that the technique could be suitable for estimation of cerebral hemodynamics. This noninvasive technique can be performed at the bedside and in special environments, such as neurocritical care units. It seems to be safe, easy to perform, and less time-consuming than conventional techniques. Combination of indocyaningreen dye dilution and near infrared spectroscopy might become a powerful tool in the detection and treatment of cerebral vasospasm causing delayed cerebral ischemic deficit. Further larger-scale investigations are necessary to evaluate the diagnostic accuracy of this technique. Our preliminary observations however, based on measurements before and after superselective papaverine infusion in vasospastic vessels, helped to clarify the influence of extracerebral contamination on the cerebral near infrared spectroscopy signal in the adult head.

Brain Chemistry↗

PubMed2001

Investigation of human brain hemodynamics by simultaneous near-infrared spectroscopy and functional magnetic resonance imaging.

The aim of this study was to compare functional cerebral hemodynamic signals obtained simultaneously by near infrared spectroscopy (NIRS) and by functional magnetic resonance imaging (fMRI). The contribution of superficial layers (skin and skull) to the NIRS signal was also assessed. Both methods were used to generate functional maps of the motor cortex area during a periodic sequence of stimulation by finger motion and rest. In all subjects we found a good collocation of the brain activity centers revealed by both methods. We also found a high temporal correlation between the BOLD signal (fMRI) and the deoxy-hemoglobin concentration (NIRS) in the subjects who exhibited low fluctuations in superficial head tissues.

Brain↗

PubMed2001

Can APC mutation analysis contribute to therapeutic decisions in familial adenomatous polyposis? Experience from 680 FAP families.

BACKGROUND AND AIMS: In familial adenomatous polyposis (FAP), correlations between site of mutation in the adenomatous polyposis coli (APC) gene and severity of colonic polyposis or extracolonic manifestations are well known. While mutation analysis is important for predictive diagnosis in persons at risk, its relevance for clinical management of individual patients is open to question. METHODS: We examined 680 unrelated FAP families for germline mutations in the APC gene. Clinical information was obtained from 1256 patients. RESULTS: APC mutations were detected in 48% (327/680) of families. Age at diagnosis of FAP based on bowel symptoms and age at diagnosis of colorectal cancer in untreated patients were used as indicators of the severity of the natural course of the disease. A germline mutation was detected in 230 of 404 patients who were diagnosed after onset of bowel symptoms (rectal bleeding, abdominal pain, diarrhoea). When these patients were grouped according to the different sites of mutations, mean values for age at onset of disease differed significantly: patients carrying APC mutations at codon 1309 showed a disease onset 10 years earlier (mean age 20 years) compared with patients with mutations between codons 168 and 1580 (except codon 1309) (mean age 30 years), whereas patients with mutations at the 5' end of codon 168 or the 3' end of codon 1580 were diagnosed at a mean age of 52 years. Within each group of patients however large phenotypic variation was observed, even among patients with identical germline mutations. A higher incidence of desmoids was found in patients with mutations between codons 1445 and 1580 compared with mutations at other sites, while no correlation between site of mutation and presence of duodenal adenomas was observed. CONCLUSIONS: As age at manifestation and course of the disease may be rather variable, even in carriers of identical germline mutations, therapeutic decisions should be based on colonoscopic findings in individual patients rather than on the site of mutation. However, in patients with mutations within codons 1445-1580, it may be advisable to postpone elective colectomy because desmoids may arise through surgical intervention.

Adenomatous Polyposis Coli↗

PubMed2001

Survey of conventional and spiral ct doses.

PURPOSE: To investigate the radiation dose for conventional computed tomography (CT) and spiral CT during different CT examinations at various hospitals and practices. MATERIALS AND METHODS: CT dose index with an active length of 15 cm was measured in 16 different types of CT scanners by using ionization chamber dosimetry. Twenty-six holders (one who has legal responsibility under national law for a radiologic installation) operating a total of seven conventional and 20 spiral CT scanners were asked for their standard parameters for various CT examinations. Weighted CT dose index and dose-length product were determined for each examination. RESULTS: For most examinations, the tube current time product was significantly higher for conventional CT than for spiral CT (.002 </= P </=.05). The ratio of section distance to section thickness for conventional CT was significantly lower than the pitch for spiral CT (.001 </= P </=.05). The weighted CT dose index and dose-length product for spiral CT were about half of those for conventional CT. The third quartiles for weighted CT dose index and dose-length product for spiral CT were much lower than those recommended as reference doses. CONCLUSION: CT examinations with conventional CT scanners are often performed with unnecessarily high radiation dose. For the establishment of reference doses, the radiation dose with spiral CT scanners should be taken into account.

Humans↗

PubMed2001

Upper jugular lymph nodes (submuscular recess) in non-squamous-cell cancer of the head and neck: surgical considerations.

Cervical lymphadenectomy of level II encompasses lymph nodes associated with the upper internal jugular vein and the spinal accessory nerve (SAN). Removal of tissue superior to the SAN (submuscular recess-(SMR)) was recently shown to be unwarranted in selected cases of squamous-cell cancer. Thirty-five patients with non-squamous-cell cancer (SCC) of the head and neck treated with cervical lymphadenectomy were prospectively evaluated. Thirty-seven neck dissection specimens were histologically analysed for the number of lymph nodes involved with cancer. At the time of surgery, level II was separated into the supraspinal accessory nerve component (IIa) and the component anterior to the SAN (IIb). Neck dissections were most commonly performed for cancer of the thyroid gland (19) followed in frequency by the parotid gland (seven), skin: melanoma (five), basal-cell cancer (two), and other sites (four). Twenty-five neck dissections were modified-selective procedures and 12 were either radical or modified radical neck dissection. Twenty-nine necks were clinically N+ and eight N0. Histological staging was pathologically N+ in 32 neck dissection specimens. Level IIb contained an average of 12 nodes and the IIa component contained a mean of 5.0 nodes. Level II contained metastatic disease in 28 of 32 histologically node-positive specimens (87 per cent). Level IIa was involved with cancer in six cases (16 per cent), five of which were pre-operatively staged as clinically N+. All cases (100 per cent) with level IIa involvement had level IIb positive nodes. Three of the level IIa positive cases were cancer of the parotid gland comprising 43 per cent of this sub-group of patients. Incidence of involvement of SMR in non-SCC cases is not uncommon. The additional time required and morbidity associated with dissection of the supraspinal accessory nerve component of level II are probably justified when performing neck dissection in cancer of the thyroid gland. The SMR should be excised in cancer of the parotid gland. Large-scale prospective controlled studies with long-term follow-up periods are necessary to support resection of level IIb only.

Adolescent↗

PubMed2001

Hodgkin's disease complicated by the nephrotic syndrome in a man with Kugelberg-Welander disease.

A case of nephrotic syndrome due to minimal change glomerulonephritis complicating Hodgkin's disease in a man with a longstanding neurological disorder is presented. Treatment with combination chemotherapy resulted in a rapid improvement in the nephrotic syndrome, and complete remission of the Hodgkin's disease. Disease relapse occurred less than 12 months later without recurrence of the nephrotic syndrome and was refractory to further treatment. The association of minimal change glomerulonephritis with Hodgkin's disease and the possible pathogenesis of this association are discussed.

Adult↗

PubMed2001

Circulating procoagulant microparticles in women with unexplained pregnancy loss: a new insight.

One of the frequently proposed mechanisms for pregnancy losses refers to uteroplacental thrombosis. However the contribution of classical thrombotic risk factors remains questionable and, if real, does not account for a large number of pregnancy losses. The aim of this study was to investigate the presence of circulating procoagulant microparticles, a new marker of cell activation already associated with various prothrombotic clinical settings. Microparticles were assessed by an original prothrombinase assay on platelet depleted plasma obtained from 74 women with a history of pregnancy loss without apparent cause and 50 controls. Patients were studied at least 2 months after the last obstetrical event and were classified into 2 groups: 49 women with at least 3 consecutive spontaneous abortions at or before the 10th postmenstrual week and 25 with at least one fetal death beyond the 10th postmenstrual week. Among the 74 patients, 41 had increased levels of circulating microparticles, 29 belonging to the group of early pregnancy loss (59%) and 12 to the group of late pregnancy loss (48%). The high prevalence of increased levels of procoagulant microparticles in both groups makes this new marker very promising for the understanding, follow up and therapeutical handling of pregnancy loss.

Abortion, Habitual↗

PubMed2001

Time-frequency analysis of breathing signals: in vitro airway model.

Sound signals of respiratory airflow represent summations of acoustic waves of various frequencies, which basically depend on the characteristics of the flow and on those of the surrounding tissue. This study was designed to examine the capability of time-frequency distribution (TFD) of respiratory signals in order to differentiate between unobstructed and obstructed upper airways. In order to investigate the TFD characteristics of defined upper airway geometry we conducted a controlled basic study in a laboratory system with an in vitro isolated airway model, which was either unobstructed or had concentric obstructions of various degrees at different locations along the tube. Pressure fluctuations were acquired with a microphone proximal to the airway opening. A short-term Fourier transform was used to study the TFDs of these signals. The results of the in vitro study showed that the energy of the higher frequencies increased for relatively small incremental changes in: i) reduction of the lumen cross-section, ii) decrease of distance from measurement site to obstruction, and iii) increase of breathing effort. Further development of this method may lead to noninvasive clinical techniques for early diagnosis of upper airway obstructions.

Acoustics↗

PubMed2001

Application of denaturing high-performance liquid chromatography for mapping of single nucleotide polymorphisms in barley (Hordeum vulgare L.).

Recent advances in DNA sequence analysis and the establishment of high-throughput assays have provided the framework for large-scale discovery and analysis of DNA sequence variation. In this context, single nucleotide polymorphisms (SNPs) are of particular interest. To initiate a systematic approach to develop an SNP map of barley (Hordeum vulgare L.), we have employed denaturing high-performance liquid chromatography (DHPLC) to analyse segregating SNP patterns in a doubled-haploid (DH) mapping population. To this end, SNPs between the parental genotypes were identified using a direct sequencing approach. Once a SNP was established between the parents, the optimal melting temperature of the PCR fragment containing the SNP was predicted for its analysis by DHPLC. Following the detection of the optimal temperature, the DH lines were analysed for the presence of either of the alleles. To test the utility of the analysis, data from previously mapped RFLP markers from which these SNPs were derived were compared. Results from these experiments indicate that DHPLC can be efficiently employed in analysing SNPs on a high-throughput scale.

Chromatography, High Pressure Liquid↗

PubMed2001

[Non-small-cell bronchial carcinoma with pathological N2 involvement: adjuvant radiotherapy versus adjuvant chemo-radiotherapy].

Fifty-eight patients, 28 of them included in a German multicenter study, were treated either with radiotherapy (5 x 2 Gy/50 Gy) or combined radio-chemotherapy (cisplatin 75 mg/m2 d1 in cases with pneumonectomy etoposide 120 mg/m2 d1-3) and Ifosfamid 1.5 mg/m2 d1-4, 3 cycles) following surgery in pN2-NSCLC. Metastatic disease or local failure was seen in 24 patients (43%), in the majority with distant metastasis (n = 21), in 4 patients combined local and distant failure. Time to progression (TTP) was 27 to 1172 days, median 244 days. Median survival of the whole group was 873 days (= 29 months), the 3-year survival 49%. Comparing the two groups there was an advantage (not significant) in favor of the combined treated group with a median survival of 1449 days versus 765 days (p = 0.22).

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Improvement of von Willebrand factor proteolysis after prostacyclin infusion in severe pulmonary arterial hypertension.

BACKGROUND: The presence of dysfunctional von Willebrand factor (vWF) in pulmonary arterial hypertension (PAH) was suggested to be related to increased proteolysis. METHODS AND RESULTS: In 10 patients with severe PAH, we studied the proteolysis of plasma vWF (vWF levels, multimeric distribution, proteolytic pattern, and cleaving protease activity) and hemodynamic variables (mean pulmonary artery pressure, cardiac index, and total pulmonary vascular resistance) at baseline and 30 days after initiation of continuous prostacyclin infusion. At baseline, vWF levels were significantly increased, vWF proteolysis was excessive, and vWF-cleaving protease activity remained normal. These biological abnormalities were reversible and paralleled the improvement of hemodynamics under vasodilator treatment with prostacyclin. CONCLUSIONS: The excessive proteolysis of vWF in PAH is likely to be related to an increased susceptibility of vWF to proteases induced by high shear rates rather than to an enhanced release of enzymes.

ADAM Proteins↗

PubMed2000

Direct observation of vibrational energy delocalization on surfaces: CO on Ru(001)

We report the experimental observation of the gradual transition from a local oscillator to a two-dimensional delocalized phonon, observed for the CO-stretch vibration of carbon monoxide adsorbed on a Ru(001) surface by means of broadband-infrared saturation sum-frequency spectroscopy. The data are theoretically reproduced by an exchange model with residence times of the excitation down to 2.5 ps.

Journal Article↗

PubMed2000

[Controversies over the surgical placebo: legal issues and the ethical debate].

The debate on controlled surgery trials has had some rather "sensational" repercussions, enlivening the placebo issue. In France, there is a consensus on the ethical conditions necessary for proper protection of individual persons. This consensus has taken on a legal form with the promulgation of the Huriet law. For this reason, all studies and research protocols in medicine and surgery are examined by ethics committees (CCPPRB) who assess the inclusion conditions within the framework of biomedical research and in compliance with the concept that individual participants must be give proper protection. These committees are faced with increasingly complex situations, particularly concerning the pertinence of information give to the participant and the modalities of consent. In France, standard measures were established after a parliamentary debate issuing from a wider public debate. The issue has become a social transaction between biomedical research professionals and the society in general. The international debate over the surgery placebo is an interesting illustration of how mediation institutions, working along the principles of ethical committees, play a key role in social awareness of the ethical issues involved before an innovating practice is initiated. But how legitimate are sensational pieces published in the media, which as is clearly demonstrated with the debate over the surgical placebo, are almost always individual points of view? Shouldn't the debate take into account the contributions of ethical committees which integrate representatives of the social community as well as the importance of a legal framework for individual protection as proposed by the French law? Shouldn't personal points of view be counterbalanced by regularly expressed ethical committee opinions formed after appropriate ethics-oriented discussion going beyond the simple question of "should we do it", a question often dismissed by extreme theoretical arguments that leave unanswered the practical question of "how should we do it"?

Controlled Clinical Trials as Topic↗

PubMed2000

Modeling of diffusion and concurrent metabolism in cutaneous tissue.

Clearance by cutaneous metabolism can shield the body from penetration of environmental and therapeutic xenobiotics. Here we report on a physical model to relate Fickian diffusion and concurrent Michaelis-Menten metabolism of drugs in the viable epidermis of human skin. For this purpose, we numerically generated substrate concentration profiles within the metabolizing tissue and the resulting donor-to-receiver substrate fluxes through the tissue for various mass transport and metabolism parameters. To validate the model, permeation and concurrent metabolism of a peptidomimetic compound, L -Ala-4-methoxy-2-naphthylamide (Ala-MNA), across both stripped human skin and HaCaT cell culture sheets were compared to numerical simulations. Parameter estimates for those calculations were extracted from independent experiments. Experimental data and numerical predictions were in excellent agreement. Also, numerical fits and independently validated parameters correlated closely, indicating the principal validity of the physical model. Numerical simulations and theoretical derivations illustrate the kinetic impact of the factors involved, i.e. the diffusion coefficient D, substrate donor concentration C(S,D), substrate partition coefficient P, tissue thickness L and maximum metabolic rate V(max), on drug permeation, with L having the strongest effect. In the steady state, the coefficient 2 alpha, i.e. the dimensionless ratio of the residence time term (L(2)/D) of a substrate in the tissue to the metabolic half-life term (C(S,D)P/2 V(max)), allows to estimate concentration gradients within the tissue and the extent of metabolism. High 2 alpha values represent practically complete metabolic cleavage upon penetration. Epidermis ( approximately 40 microm thick) of stripped human skin and HaCaT sheets ( approximately 10 microm) had 2 alpha values of 43 and 2.7, respectively, indicating that intact Ala-MNA could only permeate HaCaT sheets, but not skin. Independent permeation experiments confirmed this outcome. This physical model may be applicable to other metabolizing tissues as well.

Cells, Cultured↗

PubMed2000

Femtosecond surface vibrational spectroscopy of CO adsorbed on Ru(001) during desorption

Using time-resolved sum-frequency generation spectroscopy, the C- O stretch vibration of carbon monoxide adsorbed on a single-crystal Ru(001) surface is investigated during femtosecond near-IR laser excitation leading to desorption. A large transient redshift, a broadening of the resonance, and a strong decrease in intensity are observed. These originate from coupling of the C- O stretch to low-frequency modes, especially the frustrated rotation, that are highly excited in the desorption process.

Journal Article↗

PubMed2000

Continuous monitoring of liver oxygenation with near infrared spectroscopy during naso-gastric tube feeding in neonates.

Near infrared spectroscopy (NIRS) is a non-invasive method of estimating the haemoglobin concentration changes in certain tissues. It is frequently used to monitor oxygenation of the brain in neonates. At present it is not clear whether near infrared spectroscopy of other organs (e.g. the liver as a corresponding site in the splanchnic region, which reacts very sensitively to haemodynamic instability) provides reliable values on their tissue oxygenation. The aim of the study was to test near infrared spectroscopy by measuring known physiologic changes in tissue oxygenation of the liver in newborn infants during and after feeding via a naso-gastric tube. The test-retest variability of such measurements was also determined. On 28 occasions in 25 infants we measured the tissue oxygenation index (TOI) of the liver and the brain continuously before, during and 30 minutes after feeding via a gastric tube. Simultaneously we measured arterial oxygen saturation (SaO2), heart rate (HR) and mean arterial blood pressure (MAP). In 10 other newborn infants we performed a test-retest analysis of the liver tissue oxygenation index to estimate the variability in repeated intra-individual measurements. The tissue oxygenation index of the liver increased significantly from 56.7 +/- 7.5% before to 60.3 +/- 5.6% after feeding (p < 0.005), and remained unchanged for the next 30 minutes. The tissue oxygenation index of the brain (62.1 +/- 9.7%), SaO2 (94.4 +/- 7.1%), heart rate (145 +/- 17.3 min-1) and mean arterial blood pressure (52.8 +/- 10.2 mm Hg) did not change significantly. The test-retest variability for intra-individual measurements was 2.7 +/- 2.1%. After bolus feeding the tissue oxygenation index of the liver increased as expected. This indicates that near infrared spectroscopy is suitable for monitoring changes in tissue oxygenation of the liver in newborn infants.

Blood Pressure↗