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Biomedical subjects

M Lorenz

Publications and source records attributed to M Lorenz.

At least 19 recordsLinked to original sources
PubMed1992

Hemodynamic and electrophysiological evaluation following extracranial/intracranial bypass surgery.

We examined 50 patients with an extracranial/intracranial bypass using transcranial Doppler blood flow mapping, somatosensory evoked potentials, and computer-assisted EEG analysis. The investigation was supplemented by temporary compression of the extracranial supplying vessel. Transcranial Doppler sonography revealed in addition to 4 patients with nonpatent anastomoses, a bypass-mediated retrograde flow in the ipsilateral middle cerebral artery beyond a depth of 40 mm in the majority of patients. In 9 patients, retrograde flow could be demonstrated in the whole proximal (M1) MCA segment. The precommunicating segment of the anterior cerebral artery (A1) could be reliably insonated in all but 5 patients. Bypass-compression dependent alterations in the SSEP and in EEG analysis were only observed in a small number of patients. Transcranial Doppler sonography, with the aid of the flow mapping system, appears therefore, to be a reliable and repeatedly performable noninvasive technique for the assessment of intracranial hemodynamics following bypass surgery.

Adult↗
PubMed1992

[Initial experiences with a new cerebrospinal fluid collection system].

Due to clinical requirements and to improve the handling of CSF drainage set we developed a new concept, consisting of an arrangement of constructions, which are already available. Besides other advantages, the set provides an ICP monitoring, a pump device and a protection of the air filter of the collecting tank for safer transport. Opening the system for the performance of diagnostic or therapeutic manoeuvres can therefore be avoided. This new equipment has been tested in 28 patients having a ventricular or lumbar CSF drainage with good results and has been quickly accepted by the medical staff. The construction is described in detail.

Adolescent↗
PubMed1992

Investigations on the variability of four genetic serum protein markers in Poland.

198 unrelated male and female Poles from Ostrów Wielkopolski (Central Poland) and 228 unrelated male and female Kashubes from Kościerzyna (Northern Poland) have been typed for four polymorphic serum protein systems: HP, TF, GC, and PI. Phenotype and allele frequencies of all these four polymorphic systems are quite different between Poles and Kashubes. Comparisons with some other Central and East European population samples (Slovaks, Hungarians, Matyos, Gypsies) revealed a considerable genetic heterogeneity among them. Genetic distance analysis showed that Hungarians and Matyos as well as Poles and Slovaks are found in two subclusters, which are linked up to one cluster. Gypsies and especially Kashubes exhibit a distinct position from this cluster. This genetic distance pattern can be explained satisfactorily considering the ethnohistory of the population groups under study.

Blood Proteins↗
PubMed1992

Continuous regional treatment with fluoropyrimidines for metastases from colorectal carcinomas: influence of modulation with leucovorin.

Hepatic regional treatment represents an attempt to improve tumor response by increasing drug concentration with low systemic toxicities. Recently in vitro and clinical studies have shown that the cytotoxicity of 5-fluorodeoxyuridine (FUDR) and 5-fluorouracil (5FU) can be potentiated by high doses of leucovorin (LCV). Two pilot studies with intraarterial FUDR, 5FU, and LCV were initiated. Since 1982, 221 patients with colorectal liver metastases were treated by various forms of long-term monthly continuous regional treatment using implantable ports or pumps. FUDR (0.05 to 1.7 mg/kg/d) was administered alone or combined with 5-FU and leucovorin. In 61 patients curative liver resection was possible and was followed by adjuvant arterial treatment. Overall median survival time (MST) was 15 months and increased to 36 months after liver resection. This was influenced by the following important factors: treatment, number of metastases, extent of infiltration, tumor volume, and minimal intraoperatively diagnosed extrahepatic disease. The response rate varied from 69% to 23%. Time of development of extrahepatic progression was not delayed by additional systemic treatment. Local side effects significantly depended on the duration of arterial infusion. The rate of biliary sclerosis ranged from 19% to 0%. Occurrence of chemical hepatitis was between 7% and 38%. In contrast, after combined intraarterial treatment with LCV, systemic side effects, mainly stomatitis and diarrhea, were dose limiting. Despite the improvement of survival after regional treatment, further randomized trials are mandatory to compare regional with relevant systemic treatment.

Colorectal Neoplasms↗
PubMed1991

Effects of 33% stable xenon/O2 mixture on somatosensory evoked potentials.

The influences of 30% stable xenon/O2 mixture on somatosensory evoked potentials were investigated in 8 patients with and without Diamox application. Changes of the amplitude of the primary cortical response occurred frequently and correlated well with the psychotropical effect of xenon. They usually normalized within 2 to 3 minutes after ending xenon inhalation. There were no significant changes of the latency of the N20.

Drug Stability↗
PubMed1991

A comparison of single-level fusions with and without hardware.

During a 47-month period, 68 patients were studied prospectively to compare single-level lumbar fusion with and without adjunctive pedicular fixation. Fusion indications were disabling back pain for a minimum of 6 months, inability to work, and failed conservative care. Twenty-nine patients fused without hardware and 39 fused with VSP fixation in identical procedures. All patients were evaluated according to fusion success, perceived pain, and return to work. Pseudarthrosis was demonstrated in 58.6% of the noninstrumented group. No pseudarthroses were noted in instrumented patients. Pain improvement in the nonhardware group was 41.4%, and in the hardware group, 76.9%. Return to work was 31% and 72% in each group, respectively. The fusion rate for patients exhibiting single-level disc disease improves with spinal fixation.

Adult↗
PubMed1991

[Preventive operations of the gastrointestinal tract in precancerous conditions].

Precancerous conditions are characterized by an increased epidemiological cancer risk, precancerous lesions by a histopathological abnormality (epithelial dysplasia). Adenomas are typical examples of this in the GI tract and therefore must be removed by endoscopy or surgery. The extent of the procedure is dictated by size, growth pattern and histology. The Barrett oesophagus, chronic atrophic gastritis type B, colorectal adenomas and familial adenomatous polyposis are the most frequent serious conditions.

Adenomatous Polyposis Coli↗
PubMed1991

[SEP monitoring during clonidine therapy of alcohol delirium].

In 12 patients with developing alcohol withdrawal syndrome after abdomino-thoracic surgical procedures who were treated with Clonidine, short latency somatosensory evoked potentials were recorded. Clonidine leads to a good sedation, anxiolysis and moderated the psychotic symptoms. However, there was no significant correlation between the Clonidine medication and the SEP results over the time of drug administration concerning the primary cortical response N20 and the following N20/P25 wave. Therefore, the short-latency SEP-recording cannot provide a reliable monitoring of the good sedative effect of Clonidine in alcoholic withdrawal. The SEP responses after Clonidine are like those of morphine and are thought to have a similar central mode of action.

Alcohol Withdrawal Delirium↗
PubMed1991

[Thiamine deficiency as a cause of life threatening lactic acidosis in total parenteral nutrition].

Two patients aged 37 and 44 years developed life-threatening lactic acidosis following abdominal surgery and a period of about 3 weeks of total parenteral nutrition. Septicaemia and hypoxia were excluded as possible causes. Conventional treatment including high doses of buffer agents was unsuccessful. Thiamine (vitamin B1) depletion was suspected as the cause of the metabolic acidosis, and two doses of 400 mg thiamine were given. In both patients, the lactic acidosis improved immediately, and it disappeared following the second dose of thiamine. Both patients were subsequently discharged as symptom-free. As part of the pyruvate-dehydrogenase (PDH) complex, thiamine was capable of improving the life-threatening situation.

Acid-Base Equilibrium↗
PubMed1990

Traumatic brain swelling and operative decompression: a prospective investigation.

Since 1978, decompressive craniotomy was performed according to a standardized protocol. Exclusion criteria were age greater than or equal to 40 years, deleterious primary brain damage, operable space occupying lesions, larger infarctions in CT scan or irreversible brain stem incarceration/ischaemic damage as shown by bulbar syndrome, loss in BAEP or oscillating flow in TCD. Indication was given by progressive intracranial hypertension not controllable by conservative methods, if ICP decompensation was correlated with clinical (GCS, extension spasms, mydriasis) and electrophysiological (EEG, SEP, CCT) deteriorations. 18 patients were decompressed by unilateral. 19 by bilateral craniotomy with large fronto-parieto-temporal bone flap and a dura enlargement by use of temporal muscle/fascia. 37 patients at an age of 18 +/- 7 (4-34) years were operated 5 h-10 d after trauma. Recovery was surprisingly good: only 5 died, 2 due to an ARDS; 3 remained vegetative, all others achieved full social rehabilitation or remained moderately disabled. The best predictor of a favourable outcome was an initial posttraumatic GCS greater than or equal to 7. These in younger patients with delayed posttraumatic decompensation before irreversible ischaemic damage occurs.

Adolescent↗
PubMed1990

A critical evaluation of effectivity of extended lymphadenectomy in patients with carcinoma of the stomach. An analysis of early results and long-term survival.

The therapeutic benefit of extended lymphadenectomy in patients with gastric cancer is not generally accepted. We therefore analyzed the data of 82 patients with total gastrectomy and extended lymphadenectomy (compartment I: lymph nodes 1-6 and compartment II: lymph nodes 7-11) from 1979 to 1986 (GL group) for morbidity, mortality and survival and compared these with the results of a historical control group of 81 patients from 1971 to 1986 (group G), who similarly had undergone total gastrectomy but only compartment-I lymphadenectomy (lymph nodes 1-6). The 30-day operative mortality in the GL group was 6% (5/82), which was no higher than that of the control group (9.5%, 4/42) during the same observation period (1979-1986). The comparison of the actuarial survival according to the old TNM system (UICC 1978) in both groups showed no significant differences: stages I and II P = 0.22, stage III P = 0.29, all curative cases (stages I+II+III) P = 0.12. In addition, the patients of the GL group were restaged according to the new TNM system (UICC 1987). The calculated 5-year survival rate in this group was: stage I, 89%; stage II, 64%; stage III, 21%; curative total (stages I+II+III), 62%; stage IV, 0%. All patients (n = 12) with involvement and dissection of lymph nodes of compartment II died within 38 months. Only two of these patients (17%) had a potentially curative operation. Our results indicate that compartment-II lymph node dissection did not influence the operative mortality or the prognosis compared with compartment-I lymphadenectomy. Since patients with positive lymph nodes in compartment II did not benefit from the extended lymph node dissection of this area, obviously because of systemic spread, the question of the effectiveness of the extended lymphadenectomy remains unresolved.

Humans↗
PubMed1990

Orthotic stabilization of thoracolumbar injuries. A biomechanical analysis of the Jewett hyperextension orthosis.

Spinal orthoses have been traditionally used in the management of thoracolumbar injuries treated with or without surgical stabilization. However, the orthotic treatment modality in the management of spinal fractures remains subjective since few objective data are available on the effectiveness of orthoses in stabilizing injured segments. This study used a finite element model of the spine to evaluate the effectiveness of a hyperextension orthosis in controlling the progression of deformities at the injury site under gravitational and flexion loads. Two types of injuries were simulated: a single-level injury at T12-L1 and a two-level injury at T11-T12-L1 segments. An injury of increasing severity was simulated by progressively reducing the bending stiffness of the affected segments relative to the normal values in flexion-extension mode. The interaction of a three-point hyperextension orthosis with the spine was simulated using experimentally measured stiffness properties of the orthosis. The authors' results suggest that in single-level injuries that cause up to 50% loss of segmental stiffness, the orthosis can restore normal resistance to deformity at the injured segments, under gravitational as well as large flexion loads. In loss of stiffness between 50% and 85% of normal, such as severe two-column disruptions, the orthosis can restore resistance to deformity under restricted patient activity level in the brace (low-flexion moment). Beyond 85% loss of segmental stiffness, such as three-column injuries, the orthosis alone appears to be ineffective in preventing progression of deformity.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1990

Effects of calcifediol treatment on the progression of renal osteodystrophy during continuous ambulatory peritoneal dialysis.

Mineral metabolism was studied in 31 patients with chronic renal failure on continuous ambulatory peritoneal dialysis (CAPD) for a year. After baseline observations, 1-year calcifediol treatment was started in all the patients (100 micrograms/day). After therapy, progressive normalization of calcium levels was found in all the patients, while plasma phosphate did not change. After therapy, plasma alkaline phosphatase and parathyroid hormone decreased significantly. 1,25-Dihydroxyvitamin D showed a slight increase, and 25-hydroxyvitamin D (extremely low at the start of the study) rose, reaching normal levels, after 1 year of treatment. Bone mineral density and bone biopsy indexes showed general improvement after calcifediol. In conclusion, calcifediol seems to act positively on the disorders of mineral metabolism in CAPD.

Alkaline Phosphatase↗
PubMed1990

[Chemoembolization of primary liver cancer].

At the University of Frankfurt/M. we perform chemoembolization of the liver in patients with inoperable liver cell carcinoma. Before application of embolization material vasoconstriction of healthy blood vessels is achieved by intraarterial injection of norepinephrine. This procedure improves selectivity of tumor embolization. Methods, indications, contraindications and results are presented.

Carcinoma, Hepatocellular↗
PubMed1990

Evaluation of a possible cocataractogenic potential of Ofloxacin.

Ofloxacin, a new antibiotic of the group of quinolones, was tested for its possible cocataractogenic potential. Two cataract models of the rat, the naphthalene cataract and the true diabetic cataract were used, cataract development in-vivo was monitored with the slit lamp microscope and documented with the Scheimpflug camera Topcon SL-45. After a six weeks observation and treatment period, where Ofloxacin was dosed with 20 mg/kg body weight daily with a stomach tube, the animals were sacrificed and their lenses used for biochemical analyses. Although the results of Scheimpflug photography showed that the combination of the 2 cataract models together with the Ofloxacin treatment lead to higher densities in the cortical layer, a marked cocataractogenic potential could not be demonstrated. Also the biochemical data made it evident, that Ofloxacin has no obvious cocataractogenic potential, neither single nor in combination with 1 or 2 cataract models.

Animals↗
PubMed1990

Immunoscintigraphy using a technetium-99m labelled monoclonal anti-CEA antibody in the follow-up of colorectal cancer and other tumours producing CEA.

Using the intact monoclonal IgG1 anti-CEA antibody BW 431/26 (Behringwerke Marburg, FRG) labelled with 99mTc by a new labelling procedure (Schwarz method), 72 patients suspected of tumour recurrences (colorectal cancer, n = 59) and with rising serum carcinoembryonic antigen (CEA) levels were studied. Sixty-nine of 72 studies had a positive result by immunoscintigraphy of which 52 have since been proven histologically/clinically. In six patients only immunoscintigraphy revealed a tumour recurrence while all other diagnostic modalities were negative. Of 52 studies 46 were true positive (diagnostic sensitivity 88%). In this series there was one false positive result. About one-third of all patients injected with the antibody developed a human anti-mouse response (HAMA), but no severe side effects were seen even after four applications. For the follow-up of colorectal and other CEA positive adenocarcinomas this 99mTc-labelled monoclonal antibody seems to be very promising in patients with rising serum CEA, especially if conventional diagnostic imaging procedures remain negative.

Antibodies, Monoclonal↗
PubMed1990

Lateral ankle dislocation without fracture.

Ankle fracture dislocations are a common entity in orthopaedic practice and their treatment is well documented. Dislocations of other joints are usually treated by closed reduction with a brief period of immobilization. This ankle dislocation without fracture is a rare injury which was treated similarly to other joint dislocations. An intact bony construct of an ankle following dislocation allows for subsequent joint stability when soft tissues have healed.

Adult↗