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M Lenz

Publications and source records attributed to M Lenz.

At least 37 records · Page 2Linked to original sources
PubMed1999

A randomised comparison of three laryngoscopes with the Macintosh.

The Macintosh laryngoscope blade was compared with three modified blades--the Bizzarri-Giuffrida, the 'Improved Vision' Macintosh, and the Wiemers blade. Before and after a training session 24 participants intubated a Laerdal Airway Management Trainer with the four blades in random order. Intubation time was measured, oesophageal malpositions and 'clicks' indicating possible teeth damage, were counted. Each participant scored the handling of each blade on a 6-point scale (1 = very good, 6 = very poor). Intubation times before training were 10.6 +/- 5.3 s for the Macintosh, 16.7 +/- 9.2 s for the Bizzarri-Giuffrida, 13.3 +/- 9.0 s for the 'Improved Vision' Macintosh and 11.7 +/- 6.1 s for the Wiemers. Intubation times after training were 7.1 +/- 2.5 s for the Macintosh, 10.6 +/- 5.4 s for the Bizzarri-Giuffrida, 8.1 +/- 3.4 s for the 'Improved Vision' Macintosh and 7.6 +/- 2.5 s for the Wiemers. The handling scores were: 2.0 +/- 0.8 for the Macintosh, 3.9 +/- 1.2 for the Bizzarri-Giuffrida, 2.1 +/- 0.8 for the 'Improved Vision' and 2.3 +/- 0.8 for the Wiemers. In regard to the intubation time before training (P < 0.02), the intubation time after training (P < 0.003), and handling (P < 0.0005), the Bizzarri-Giuffrida was significantly inferior to the Macintosh. The 'Improved Vision' Macintosh and the Wiemers were not significantly different to the Macintosh. No significant difference was seen for oesophageal malpositioning and 'clicks' between any of the blades.

Equipment Design↗
PubMed1999

Gd-BOPTA: "the MRA contrast agent of choice"?

Gd-BOPTA is a new positive MR contrast agent for intravenous application. In comparison to other gadolinium-chelates it has a nearly two-fold increased relaxivity due to weak protein binding with plasmatic macromolecules. In the papers published yet it has been evaluated to be useful for liver imaging. The purpose of this study was to evaluate, whether Gd-BOPTA is suited as an "magnetic resonance angiography (MRA) contrast agent". We examined four patients (aortic dissection, carotid artery stenosis, portal vein stenosis, exclusion of subclavian artery stenosis) with Gd-BOPTA with a dosage of 0.05 mmol/kg body weight. Furthermore, peripheral MRA of the pelvis and lower extremities was acquired in two healthy volunteers comparing 0.1 mmol Gd-DTPA/kg with 0.1 mmol Gd-BOPTA/kg. There was a delay of one week between the Gd-DTPA and the Gd-BOPTA examinations. In another volunteer Gd-BOPTA was reduced to 0.05 mmol/kg. The patient examinations revealed sufficient quality comparable with Gd-DTPA examinations despite of reduced dosage. In the volunteers Gd-BOPTA proved to be superior especially in the delineation of small pedal arteries which is important for surgical planning. These preliminary results demonstrate the potential of Gd-BOPTA to become a useful contrast agent for MRA. Its efficacy for this purpose has to be evaluated in future prospective studies.

Aortic Valve Stenosis↗
PubMed1998

High expression, purification, and properties of recombinant homocysteine alpha, gamma-lyase.

Homocysteine alpha,gamma-lyase from the anaerobic protozoan parasite Trichomonas vaginalis has been cloned from genomic DNA using PCR methods and expressed in Escherichia coli with a vector containing the T7 promoter. The recombinant homocysteine alpha,gamma-lyase (rHCYase) is expressed as the major protein in the host E. coli cells. The enzyme was purified to approximately 90% purity using heat treatment at 50 degreesC, precipitation steps with polyethyleneimine, polyethylene glycol 8000, and high sodium chloride, DEAE-Sepharose FF chromatography, and phenyl-Sepharose 6 FF chromatography. The final yield was greater than 50%, which encompassed an approximate 18-fold purification. The enzyme is a homotetramer with a monomer molecular weight of 43K and contains pyridoxal phosphate. The Trichomonas rHCYase is selective for homocysteine with respect to very low cysteinase activity in contrast to the alpha,gamma-lyase from Pseudomonas putida, which has very high cysteinase activity with respect to homocysteine. The T. vaginalis and P. putida alpha,gamma-lyases readily separate on a phenyl-Sepharose 6 FF column with the T. vaginalis enzyme eluting first. rHCYase is stable up to 50 degreesC and active over a pH range of 6-8. These properties of high recombinant expression in E. coli, a simple and effective high-yield purification procedure and high relative specificity for homocysteine with respect to cysteine, make rHCYase a promising candidate to use for the diagnosis of hyperhomocystenemia, which has been demonstrated to be a major risk factor for the onset and mortality of cardiovascular disease of all types.

Animals↗
PubMed1998

Volume replacement strategies on intensive care units: results from a postal survey.

OBJECTIVE: To assess volume replacement strategies on intensive care units (ICUs) in Germany. DESIGN: A postal survey questionnaire of 18 questions was sent to 451 ICUs in Germany. The questionnaire was sent to general, surgical, anesthesiology, neurosurgery, cardiac surgery, and medical ICUs of hospital with more than 200 beds. RESULTS: 286 questionnaires (64%) were returned and analysed. Hydroxyethylstarch (HES) solution is the solution most often used for volume replacement (total: 193 ICUs, exclusively HES: 93 ICUs), crystalloids are next (crystalloids exclusively: 61 ICUs), and human albumin is used rarely as a first choice. Clinical experience is a very important argument for administering volume. Diagnostic tools, e.g. measurement of central venous pressure or pulmonary capillary wedge pressure, also play an important role. Albumin/total protein and colloid osmotic pressure (COP) are measured often on ICUs (albumin measured routinely: 173 ICUs; COP measured routinely: 33 ICUs). Critical values for albumin/total protein are defined in most ICUs. Reduced plasma levels of albumin/total protein was the indication most often cited for administering human albumin. Only 149 ICUs (52%) have a financial budget for their unit. Costs still do not play a major role in the choice of volume replacement on 30 ICUs (10%). CONCLUSIONS: The kind of volume therapy differs widely among the different ICUs. This questionnaire supported the supposition that no standards exist for volume therapy in intensive care patients. New results concerning the abuse of albumin in the critically ill have not yet influenced strategies of volume replacement.

Albumins↗
PubMed1998

Guidelines for prescribing melatonin.

Although compelling logic suggests that melatonin may be effective for a variety of disorders, there are few empirical clinical studies. The optimal dose of melatonin is not clear; most studies have used doses that produce supraphysiological blood levels. The timing of melatonin administration is important. Melatonin has few immediate side-effects except drowsiness, but the effects of chronic administration are unclear. Melatonin may be effective in reducing jet lag. In elderly patients with poor sleep and documented low melatonin production, melatonin may be helpful. In several studies, melatonin has been shown to shorten sleep latency. Further studies are needed to clarify the efficacy and safety of melatonin.

Aged↗
PubMed1998

Some aspects of intracellular symbiosis during embryo development of Mastotermes darwiniensis (Isoptera: Mastotermitidae).

All examined species of cockroaches have been shown to harbour intracellular bacteria in specialized cells (bacteriocytes) of the fat body. In termites, bacteria in specialized cells have been observed only in Mastotermes darwiniensis (Isoptera: Mastotermitidae). All of these bacteria have been assigned to the same eubacterial lineage, with the bacteria of M. darwiniensis as the sister group to the cockroach bacteria. While the main steps of the life cycle of cockroach bacteria have been described, little is known about the bacteria of M. darwiniensis. More specifically, no data are available on their behaviour during the development of this termite. Using both optical and electron microscopy methods, we examined embryos of M. darwiniensis at different developmental stages. Our results show that the integration of bacteria during the development of M. darwiniensis is implemented in the same way as in cockroaches. In particular, we observed the aggregation of a large amount of bacteria in a single mass in the yolk sac, with vitellophage-associated bacterial lysis. In cockroaches, a similar process has been described in detail for Periplaneta americana (Blattaria: Blattidae), where the bacterial mass is referred to as the transitory mycetome. The formation of a transitory mycetome could thus be regarded as an ancestral condition for cockroaches and termites.

Animals↗
PubMed1997

Overexpression and large-scale production of recombinant L-methionine-alpha-deamino-gamma-mercaptomethane-lyase for novel anticancer therapy.

The goal of the next generation of cancer chemotherapy is effective tumor-selectivity. A tumor-selective target with high therapeutic potential is the elevated methionine requirement of tumor cells relative to normal cells. We have termed the elevated requirement for methionine in tumors methionine dependence. To selectively target the methionine dependence of tumors for treatment on a large-scale preclinical and clinical basis, the L-methionine alpha-deamino-gamma-mercaptomethane-lyase (methioninase, METase) gene from Pseudomonas putida has been cloned in Escherichia coli using the polymerase chain reaction (PCR). The METase gene was then ligated into the pT7-7 overexpression plasmid containing the T7 RNA polymerase promoter and recloned in E. coli strain BL21(DE3). The pAC-1 clone was isolated by its yellow-orange color which is due to high enrichment of the pyridoxal phosphate-containing recombinant methioninase (rMETase) and distinguished rMETase-overproducer from rMETase-negative colonies. A scale-up production protocol which contained a heat step, two DEAE Sepharose FF ion-exchange, and one ActiClean Etox endotoxin-affinity chromatography columns has been established. The pAC-1 clone produces rMETase at approximately 10% of the total soluble protein and up to 1 g/liter in shake-flask culture. The protocol can produce therapeutic rMETase at the multi-gram level per batch with high yield (> 60%), high purity (> 98%), high stability, and low endotoxin. Purified rMETase is stable to lyophilization. The t1/2 of rMETase was 2 h when rMETase was administered by i.v. injection in mice. Studies of the antitumor efficacy of rMETase in vitro and in vivo on human tumors xenografted in nude mice demonstrated that all types of human tumors tested including those from lung, colon, kidney, brain, prostate, and melanoma were sensitive to rMETase. In contrast, normal cells were insensitive to rMETase in vitro and correspondingly, no toxicity was detected in vivo at the effective doses. In conclusion, the overexpression clone and large-scale production protocols for rMETase have enabled rMETase to be used as a tumor-selective therapeutic with broad indication and high promise for effective, low-toxicity human cancer therapy.

Amino Acid Sequence↗
PubMed1996

Imaging of the oropharynx and oral cavity. Part I: Normal anatomy.

This article reviews the anatomy of the oropharynx and oral cavity, as seen on CT and MR imaging studies. Emphasis is placed on the description and illustration of the structures which are of importance to detect tissue alterations and interprete them adequately. Common pitfalls in the image interpretation of this region are indicated.

Humans↗
PubMed1996

MRI of peripheral joints with a low-field dedicated system: a reliable and cost-effective alternative to high-field units?

In the age of health care cost containment new imaging technology has to meet diagnostic requirements as well as economic limitations. In the MR sector new dedicated systems promise reliable diagnostic information at considerably lower costs than whole-body imagers. Within the past 18 months we have examined 2200 patients with acute and chronic lesions of peripheral joints (knee, ankle, foot, elbow, wrist, hand) in a 0.2T dedicated MR system (ARTOSCAN, Esaote Biomedica, Genoa, Italy). We report our experience with this system focusing on its special features, cost-effectiveness and on diagnostic accuracy of low-field MR studies of the knee in correlation with arthroscopy and in comparison with high-field whole-body imagers.

Acute Disease↗
PubMed1996

Anatomic variants of the spermatic vein: importance for percutaneous sclerotherapy of idiopathic varicocele.

PURPOSE: To evaluate percutaneous sclerotherapy of idiopathic varicocele in left internal spermatic vein variants. MATERIALS AND METHODS: The left spermatic vein was embolized with a liquid sclerosing agent in 386 patients (mean age, 29.5 years) with idiopathic varicocele. Success and complication rates were assessed and correlated with spermatic vein variant. Doppler ultrasound was performed 3 and 6 months after therapy in 263 patients. RESULTS: The success rate was 93.8% (n = 362). Perforation of the vein was the most common complication (n = 24). The recurrence rate was 3.8% (10 of 263 patients). Success and complication rates were associated with spermatic vein variant. Type IVb (intact valve of the main trunk, insufficient collateral vessels; n = 73) was of special importance: 67% (16 of 24) of all perforations occurred and 54% (13 of 24) of all unsuccessful interventional procedures were performed in patients with this variant. CONCLUSION: Sclerotherapy is a safe and effective alternative treatment of idiopathic varicocele. It can be performed on an outpatient basis. Success depends on the anatomic variant.

Adult↗
PubMed1996

[Miniplate osteosynthesis of mandibular fracture in local anesthesia--indications and outcome in 316 patients].

In an retrospective analysis of 316 patients with mandibular fractures treated between 1984 and 1993 at the maxillo-facial surgery of university of Cologne could be shown that the application of miniplate in local anesthesia causes no more complication than in general anesthesia. We would therefore recommend this technique for not to complicated cases of isolated or double fractures of the mandible. In cases of obstacles to general anesthesia it may be favoured even in severe cases.

Adolescent↗