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Biomedical subjects

H Steinhoff

Publications and source records attributed to H Steinhoff.

At least 19 recordsLinked to original sources
PubMed2000

High-field EPR studies of the structure and conformational changes of site-directed spin labeled bacteriorhodopsin.

Cw and pulsed high-field EPR (95 GHz, 3.4 T) are performed on site-directed spin labeled bacteriorhodopsin (BR) mutants. The enhanced Zeeman splitting leads to spectra with resolved g-tensor components of the nitroxide spin label. The g(xx) component shift determined for 10 spin labels located in the cytoplasmic loop region and in the protein interior along the BR proton channel reveals a maximum close to position 46 between the proton donor D96 and the retinal. A plot of g(xx) versus A(zz) of the nitrogen discloses grouping of 12 spin labeled sites in protic and aprotic sites. Spin labels at positions 46, 167 and 171 show the aprotic character of the cytoplasmic moiety of the proton channel whereas nitroxides at positions 53, 194 and 129 reveal the protic environment in the extracellular channel. The enhanced sensitivity of high-field EPR with respect to anisotropic reorientational motion of nitroxides allows the characterization of different motional modes for spin labels bound to positions 167 and 170. The motional restriction of the nitroxide at position 167 of the double mutant V167C/D96N is decreased in the M(N) photo-intermediate. An outward shift of the cytoplasmic moiety of helix F in the M(N) intermediate would account for the high-field EPR results and is in agreement with diffraction and recent X-band EPR data.

Bacteriorhodopsins↗
PubMed1993

[Venous MR angiography for the primary diagnosis and follow-up of sinus venous thrombosis. The correlation with the clinical picture and DSA].

30 patients clinically suspected of suffering from venous sinus thrombosis were examined by MRT with venous MR angiography (FLASH 2-D). In 8 patients selective arterial angiography was also performed and 5 patients were followed up by MR angiography after an interval of three months. The MRT images and individual MR angiography images were analysed and 3-D reconstruction performed. In 11 patients MR angiography correctly demonstrated venous sinus thrombosis; the most frequently affected were the superior sagittal sinus, the ascending cerebral veins and the transverse sinus. Compared with DSA, magnetic resonance angiography achieved a high degree of accuracy in our patients. It was significantly better in evaluating the basal sinus system whereas thrombosis of individual ascending veins was better shown by DSA. In summary, primary use of MRT and MR angiography is recommended for the diagnosis of venous sinus thrombosis.

Adult↗
PubMed1988

[Angiographically confirmed vasospasm following aneurysmal subarachnoid hemorrhage: does the quantity of the primary diagnostic contrast medium modify the incidence of vasospasm?].

Prognosis after subarachnoid haemorrhage secondary to a ruptured intracranial aneurysm is greatly influenced by arterial vasospasm. In 50 patients the influence of the amount of subarachnoid blood detected by CT and the amount of the nonionic contrast medium on the postoperative vasospasm and the outcome of the patient were investigated. For angiographically proven vasospasm, a grading system is suggested. There was a good correlation between the extent of the haemorrhage and the development of cerebral vasospasm. If used within limits, the volume of the contrast medium does not seem to exercise any influence on the development of vasospasm and on the results after treatment. Therefore, a complete investigation of the cerebral vascular system should be performed before surgical management of the ruptured cerebral aneurysm is initiated.

Adult↗
PubMed1987

[Elimination of the obturator reflex with prilocaine in transurethral resection of bladder tumors in combination with spinal and general anesthesia].

During transurethral resection of bladder tumors under either spinal or general anesthesia without muscular relaxation, direct stimulation of the obturator nerve by the electroresectoscope is possible. The resulting obturator reflex may lead to severe complications, at the worst to a perforation of the bladder. Therefore, if resection in lateral bladder regions is necessary, blockade of the obturator nerve is often required to provide optimal conditions for transurethral resection of bladder tumors. To interrupt the obturator reflex are, we blocked the inguinal lumbar plexus using the "3-in-1-block" as described by Winnie because of its advantages compared to isolated blockade of the obturator nerve. Prilocaine 1% was the chosen local anesthetic because of its low tendency towards cardiac and cerebral side effects. Spinal anesthesia was induced with 3-4 ml hyperbaric bupivacaine 0.5%. After the onset of analgesia, making use of a nerve stimulator, a "3-in-1-block" was completed with 30-35 ml prilocaine 1%. The study included over 90 patients. Firstly we observed the efficiency of the obturator motor block by the "3-in-1-block"; secondly clinical side effects of prilocaine were evaluated; and finally in 20 cases methemoglobin levels were measured before and 90 min after injection of prilocaine. A "3-in-1-block" with prilocaine 1% provided a good motor block of the obturator nerve. Neither clinical side effects nor relevant methemoglobinemia occurred. In 3 cases methemoglobin levels were elevated by 1%, whereas in the remaining 17 cases methemoglobin values were normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1986

[Nuclear magnetic resonance tomography of the spine and spinal cord compared with computed tomography and myelography].

In cases of syringomyelia MR is superior to CT and myelography in visualisation and delineation of the extent of the process. In diagnosing spinal tumours MR is a more sensitive method than CT and myelography. MR provides additional information on sagittal and frontal planes regarding the extent of the tumour. In diagnosis of disc prolapse MR seems to be as accurate as CT or myelography. We obtained additional information in diagnosis of degenerated disc tissue. Spinal stenosis is easily recognisable. CT was superior in differentiation of bony and disc protrusion. The results show that MR has opened up new possibilities in the diagnosis of spinal diseases and will result in a reorientation of the diagnostic approach.

Arteriovenous Fistula↗
PubMed1986

Magnetic resonance imaging compared with computed tomography and myelography in the diagnosis of spinal masses.

Magnetic resonance imaging (MRI) is superior to computed tomography (CT) and myelography in the demonstration and delineation of the extent of syringomyelia. In the detection of intramedullary tumors MRI is more sensitive than CT and myelography. MRI provides additional information on the sagittal and frontal planes regarding the extent of tumors. In the diagnosis of disc prolapse MRI seems to be as accurate as CT or myelography. Additional information is available with MRI in the diagnosis of degenerated disc tissue. Spinal stenosis is easily recognizable. CT was superior in the differentiation of bony and disc protrusion. The results show that MR has opened up new possibilities in the diagnosis of spinal diseases and will lead to a reorientation of the diagnostic approach.

Diagnosis, Differential↗
PubMed1984

[New possibilities of radiologic diagnostic methods for diseases of the spinal column using spinal computer tomography].

During the last there years (from May 1981 to March 1984) we performed 1368 CT examinations of the spine, 447 of the cervical, 264 of the thoracic and 657 of the lumbar vertebral column. 30% of the CT examination of the lumbar spine revealed a prolapse of an intervertebral disk. In 38% of the cases involving the thoracic spine metastases were seen. We diagnosed fractures in 10% of the cervical spine and 11% of the thoracic spine examinations. Posttraumatic or postoperative intravertebral haemorrhage was hardly ever diagnosed in our patients (1.9% of the cases). Spinal trauma: The anterior-posterior and lateral plain films continue to be the mainstay of radiographic screening in spinal injury. Nevertheless, the degree of injury is underestimated in a significant number of patients with spinal trauma if conventional radiography is the only diagnostic approach. For further clarification CT proved to be the fastest and best method to recognise the causes and extent of compression of the vertebral canal. CT has attained a high degree of accuracy in the diagnosis of prolapse of intervertebral disks, replacing myelography if the findings are unequivocally established. CT should also be preferred to myelography in suspected recurrent prolapse. Localisation, shape and density are criteria for differentiating between scarification and prolapse via CT. The results show that CT has opened up new possibilities in the diagnosis of spinal diseases and has resulted in a reorientation of the diagnostic approach.

Humans↗
PubMed1984

[Carotid aneurysm following apparent complications in catheterization of the internal jugular vein].

During resuscitation of a patient wih ruptured abdominal aortic aneurysm his right internal jugular vein was cannulated with a 12 gauge catheter-through-cannula assembly (Cavafix 458, Braun-Melsungen), using a high central approach, without any apparent complications. Five weeks later a dissecting aneurysm of the right common carotid artery developed. From clinical, angiographic and histological data it is very likely that the aneurysm resulted from the catheterization procedure.

Aortic Dissection↗
PubMed1983

[Anesthesia problems in extreme obesity].

Obese patients show a markedly increased perioperative morbidity and mortality. Due to the severe impairment of his cardiopulmonary system the extremely obese patient is at high risk. Among the abundant pathophysiologic disorders which in less severe form can also be traced in minor obesity, are reductions in functional residual capacity and total compliance as well as oxygen costs of breathing that are increased by a factor of 4-16. On the basis of current knowledge of these pathophysiologic disorders guidelines for the management of the obese patient in the perioperative period are proposed.

Anesthesia↗
PubMed1982

Enhanced renal function associated with intermittent mandatory ventilation in acute respiratory failure.

In ten patients suffering from acute respiratory failure (ARF) renal function was evaluated during 2-h periods of intermittent mandatory ventilation (IMV) or controlled mechanical ventilation (CMV). Urine flow, osmolal and creatinine clearances were significantly lower during CMV in comparison to both IMV phases and the free water clearance was less negative. Potassium excretion declined with CMV but remained reduced during the second IMV phase. There was no change in sodium excretion. This study suggests that in order to maintain renal function and prevent water retention the use of IMV should be considered whenever a sufficient mechanical reserve for partial spontaneous ventilation is present.

Acute Disease↗
PubMed1981

[Iatrogenic secondary retroperitoneal fibrosis (secondary Ormond disease) caused by contrast medium enema, and the treatment of the resulting hydronephrosis with endourethral splinting ("endoprosthesis")].

A case of secondary retroperitoneal fibrosis with bilateral hydronephrosis, following a barium enema is presented. The mechanism of perforation and the ways of perforation are being discussed. The importance of early surgical intervention is stressed. For treatment of the hydronephrosis an endoureterine splinting was indicated.

Aged↗
PubMed1980

[Combined epidural anaesthesia as an alternative to inhalation anaesthesia as exemplified in radical lymphadenectomy in testicular malignomas (author's transl)].

In a retrospective study of retroperitoneal lymph-adenectomy it was investigated whether the choice of anaesthesia and the difference in management of postoperative pain alleviation does influence the postoperative course. In comparing group I (n = 43), patients anaesthesized with volatile anaesthetics (enflurance, halothane) while postoperative pain relief was obtained by meperidine and pentazocine and group II (n = 28), anaesthesized with a high epidural block combined with light narcosis with oxygen, nitrous oxygen and diazepam, while postoperative pain relief was obtained by a continuous epidural block we found: In comparison to group I the stay in group II was shorter. There was one patient in group II with intestinal obstruction, but in group I were seven patients with clinical signs of intestinal obstruction. In group I the evaluation of the bowel took place after 36 hours, in group II after 20 hours. One patient in group I died after three days because of pneumonia combined with intestinal obstruction. The consumption of meperidine and pentazocine in comparison group II to group I were diminished to round about 85%. We think that there is a direct relation between anaesthesia, postoperative pain alleviation and the postoperative course. High epidural anaesthesia in combination with light anaesthesia and postoperative epidural analgesia seems to be better than inhalational anaesthesia for the patients we explored in our retrospective study.

Anesthesia, Epidural↗
PubMed1979

[The kinetics of contrast media in cerebral tumours (author's transl)].

The increase in density of cerebral tumours following intravenous injection of contrast media was measured by computer tomography and was evaluated quantitatively. The density increase of 158 tumours five minute after injection was between 0 and 29 CT units. There are considerable variations in density increase of various types of tumour, but the scatter is so wide as to preclude a diagnosis of tumour type. In 75 tumours repeated measurement of contrast changes were carried out for two hours following the injection. Again the variation differs with different types of tumour, but is not characteristic enough for exact clinical diagnosis. In 26 patients contrast concentrations were measured in the tumour and the blood and a pharmaco-kinetic compartmental analysis was carried out. In some tumours contrast changes can be explained by a single compartment model, whereas in others a two compartment model is necessary. Certain conclusions regarding the mechanism of contrast uptake can be reached.

Absorptiometry, Photon↗
PubMed1979

Sensitivity of computed tomography and serial scintigraphy in cerebrovascular disease.

Computed tomography and serial scintigraphy with 99mTc-pertechnetate (radionuclide angiography and early and late static imaging) were compared in 214 patients with cerebrovascular disease. CT correctly identified 151 (95.0%) of 159 patients with completed ischemic stroke but was positive in only 11 (25%) of 44 patients with asymptomatic stenosis, transient ischemic attacks (TIA), or prolonged reversible ischemic neurological deficit (PRIND). Scintigraphy was positive in 93.1% of patients with completed stroke. CT detected 175 territories of vascular supply involved, scintigraphy 164. In patients with asymptomatic stenosis, TIA, or PRIND, scintigraphy was correct in 77.3% of cases. The combined evaluation offered a sensitivity of 97.5% in patients with completed stroke and 86.4% in those with asymptomatic stenosis, TIA, or PRIND. The rate of true-positive scintigraphic findings in patients with completed stroke did not change as the interval between ictus and study increased. In patients with intracerebral hematoma, CT was far more specific than scintigraphy. If cerebrovascular disease is suspected, radionuclide angiography should be performed first.

Adult↗