Biomedical subjects
L Steiner
Publications and source records attributed to L Steiner.
Angiographic investigation of cerebral vasospasm in subarachnoid haemorrhage due to arteriovenous malformation.
Fifty (50) selected patients with arteriovenous malformation (AVM) with and without subarachnoid haemorrhage (SAH) were investigated, in respect of occurrence and course of the vasospasm. The diameters of the carotid siphon and its main branches were measured and plotted against the time elapsing between the haemorrhage and the angiographic study. Patients without SAH were used as a reference group. The results suggest intracranial arterial spasm to occur between the third and eleventh day after the onset of SAH. Patients with intracerebral haematoma may show vasospasm from the first day onwards. It seems that the radiologically demonstrated spasm in AVM had no impact on the clinical outcome in this series.
Gastric H+-K+-ATPase in situ: relation to secretory state.
Isolated gastric glands from rabbit were used to measure the gastric H+-K+-adenosinetriphosphatase (ATPase) and its partial reaction, a K+ p-nitrophenyl phosphatase (pNPPase), in situ. Measurement of the enzyme activities required permeabilization of the cells with digitonin and the use of several ATPase inhibitors to reduce nonspecific activity. The enzyme activities were identified as the H+-K+-ATPase according to the following criteria: dependence on K+, association with parietal cells, insensitivity to ouabain and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, and inhibition by the specific inhibitors omeprazole and Sch 28080. K+-stimulated ATPase, but not K+-pNPPase, was enhanced by K+ ionophores, valinomycin and nigericin, with nigericin resulting in the greatest activity. Comparison of tissues that were preincubated to establish resting and stimulated states showed that prestimulation results in an increase in K+-stimulated ATPase activity with no change in the total activity. With the use of a two-step assay procedure, it could be shown that stimulation also results in an increase in the omeprazole-sensitive maximal ATPase activity. These results indicate that the major effects of stimulation are to enhance KCl activation of the enzyme and to increase the number of active enzyme molecules.
Stimulation of acid formation in permeable gastric glands by valinomycin.
Isolated gastric glands made permeable with digitonin treatment were employed to study the ionic requirements of acid formation. Acid formation was monitored by the accumulation of a novel weak base probe, [14C]benzylamine. ATP-dependent acid formation was found to require K+ in a concentration-dependent manner, with an apparent K0.5 = 7 mM. The anion dependence of acid formation gave a selectivity sequence of Cl = I greater than Br greater than NO3 greater than SO4 = isethionate, with isethionate being approximately 50% as effective as Cl. The dependence of acid formation on [Cl] gave an apparent K0.5 = 6 mM. Addition of the K+ ionophore, valinomycin, to resting glands (cimetidine pretreatment) resulted in a two- to threefold increase in ATP-dependent acid formation. In contrast, stimulated (forskolin pretreated) glands showed a greater accumulation of benzylamine with ATP but significantly less valinomycin stimulation. The valinomycin stimulation required both K+ and Cl- and was inhibited by omeprazole and Sch 28080. The results are interpreted to indicate that major events in the transition from a resting to a stimulated state include changes in both K+ and anion permeability of the secretory membrane of parietal cells.
Plasma lipolytic activity. Relationship to postheparin lipolytic activity and evidence for metabolic regulation.
Lipolytic activity was measured in human plasma without prior administration of intravenous heparin. Eluted from heparin-Sepharose in a barbital buffer containing 6 mg/ml heparin, plasma lipolytic activities in 20 subjects were distributed between hepatic triglyceride lipase (HTGL, mean +/- SE 60.6 +/- 4.6%) and extrahepatic lipoprotein lipase (LPL, 39.4 +/- 4.6%). Confirmation of the identities of HTGL and LPL was provided by inhibitory antisera. Preheparin LPL activity was absent in plasma from a patient with type I hyperlipoproteinemia. Both preheparin HTGL and LPL activities correlated with the respective activities measured in plasma obtained 15 min after intravenous injection of heparin (rs = + .774 and + .685, respectively; n = 12). Evidence for the metabolic regulation of preheparin lipases was provided by measurement of significant increases in LPL and HTGL activities after oral glucose ingestion. Overall, preheparin plasma HTGL and LPL activities may reflect ongoing lipoprotein lipolytic activity in tissue beds, and because these measurements do not require the administration of intravenous heparin, they should prove useful for additional studies of short-term regulation of the lipases.
Natural history of postoperative aneurysm rests.
In a series of 715 patients operated on by microsurgical techniques for intracranial saccular aneurysms between 1970 and 1980, part of the aneurysmal sac was not obliterated in 28 aneurysms in 27 patients (3.8% of 715 cases). Clinical follow-up evaluation for 8 years (range 4 to 13 years) and angiographic follow-up studies for 6 years (range 2 to 10 years) in these 27 cases revealed that one aneurysm rest increased in size and bled twice, five were spontaneously obliterated, two decreased in size, 13 remained unchanged, and in seven cases no late follow-up angiography was performed. The incidence of rebleeding from an aneurysm rest was 3.7% of the 27 in whom the sac was not obliterated and 0.14% of all 715 patients who were operated on.
A new fixation device for the Leksell stereotaxic system. Technical note.
A device is presented that permits several applications for the Leksell stereotaxic system. The patient is fixed in this new system by means of a rectangular instrument that connects to the standard Leksell stereotaxic coordinate frame and maintains spatial orientation after the frame itself is removed. Specific uses for this device include stereotaxic radiosurgery and stereotaxic guidance during microsurgery. Other attractive features of this device are its capability of being precisely reapplied, its compatibility with both computerized tomography and magnetic resonance imaging, and the availability of an accessory device to adapt it for animal stereotaxis.
Stereotactic radiation therapy of intracranial arteriovenous malformations.
Twenty-six patients with large intracranial arteriovenous malformations (AVM), not suited for open surgery or radiosurgery, have been treated by fractionated stereotactic radiation therapy using a linear accelerator. The preliminary results are based on follow-up angiography one and a half years after treatment, and in 5 cases also 5 years after treatment. In 2 cases a complete obliteration of the AVMs has occurred, and in the majority of the remaining cases a reduction of the size of the lesion has been obtained. Further development of the method is needed in order to improve the results. Today treatment with this technique is only recommended in cases which cannot be treated with other methods.
Acid formation by permeable gastric glands: enhancement by prestimulation.
Digitonin was used to render isolated gastric glands permeable. This procedure was found to release cellular lactic dehydrogenase without disrupting the parietal cell's ability to generate proton gradients. Optimal conditions for permeabilizing the glands were found to depend on the ratio of digitonin to gland concentration. Stimulation of the glands with histamine, forskolin, or 8-bromo-cAMP prior to digitonin treatment resulted in a marked enhancement of the subsequent ATP-dependent acid formation. This enhancement was not found with the cholinergic agonist carbachol. These results indicate that preservation of the active secreting state does not require the continued presence of soluble factors. Characterization of the ATP-dependent acid formation in prestimulated permeable glands showed a dependence on exogenous substrate and inhibition by the mitochondrial inhibitors oligomycin and atractyloside. Moreover, it was found that ADP could replace ATP in promoting acid formation. These results are interpreted to show that mitochondrial oxidative phosphorylation can serve as an in situ ATP-recycling system to provide a local supply of ATP for proton transport. The overall study demonstrates that the digitonin-permeabilized gastric gland preparation is a valuable model system for studying mechanisms of gastric proton transport.
Immunological monitoring of patients affected by anaplastic glioma concerning in effects of surgery, radio-, and chemotherapy. A preliminary report.
The authors studied 24 patients affected by anaplastic gliomas, as regards immunology. In all of them the authors evaluated the lymphocyte subpopulation (B and T), firstly by simple lymphocyte count, secondly by studying the rosettes E-total and EAC, thirdly by stimulating the lymphocytes with mitogens phyto-haemoagglutinin-P (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM), and lastly by counting the release of Cr51 in Chang liver cells culture in order to obtain antibody dependent cellular cytotoxicity (ADCC). The parameters were also evaluated after surgery and during conventional radio-chemotherapy with BCNU. Whereas the so-called B-pool seems to be unaffected, the preliminary results show that the T-pool (identified by the E-t rosettes and by responses to PHA, PWM, and ConA) is depressed to a statistically significant degree, if compared with a control group. This depression seems to be related to the tumoral mass, and it is not increased by radio-chemotherapy. In addition, ADCC also seems to be depressed in our glioma patients in comparison with a control group and witha group of bladder cancer patients.
Effect of leucotrienes C4, D4, prostacyclin and thromboxane A2 on isolated human cerebral arteries.
The effects of leucotrienes C4 (LTC4), D4 (LTD4), Prostacyclin (PGI2) and Thromboxane A2 (TXA2) were studied on superfused human cerebral artery strips. LTC4 and LTD4 neither contracted nor relaxed the strips. PGI2 caused a dose-dependent relaxation from 0.2 nmol to 0.8 nmol. When given simultaneously with a vasoconstrictor substance, PGI2 had an almost complete inhibitory effect. TXA2 caused a dose-dependent contraction from 0.03 nmol to 0.15 nmol. Also, TXA2 was more potent than 5-hydroxytryptamine (5-HT) and prostaglandin E2 (PGE2) with a contraction threshold of about 0.1 nmol. Prostaglandin E1 (PGE1), H2 (PGH2), and F2a (PGF2a) had contraction thresholds of about 1 nmol. Only a stable endoperoxide analogue (EPA), was more potent than TXA2, with a contraction threshold of 0.005 nmol. The possible role of these substances in producing ischaemic manifestations after subarachnoidal haemorrhage (SAH) is discussed.
Disposable brain shield adapted to the brain retractor. A technical note.
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Computed tomography for anterior sacral and intracorporal meningoceles.
Two cases of recurrent anterior spinal meningocele are presented. Both cases were studied by CT. One of them was also investigated by ultrasonography. The value of these methods in the diagnosis of anterior spinal meningoceles is discussed.
Titanium, silver, and tantalum clips in brain tissue.
The brain tissue reaction to a recently devised titanium haemoclip and to the conventional silver and tantalum clips were investigated in rabbit brain. Titanium, silver, and tantalum wires 5 X 0.5 X 0.5 mm in size were implanted into the white matter of the brain. After one and six months the brain specimens were sectioned, stained with haematoxylin eosin and with phosphotungstic acid Haematoxylin, and were studied by light microscopy. The examination revealed neither tissue reaction nor pigmentation in the case of titanium implant, while there was pigmentation surrounding the tantalum, and there was pigmentation as well as reactive gliosis around the silver wires.
Gammathalamotomy in intractable pain.
Thalamotomy aiming at the CM-Pf complex and using stereotactic gamma irradiation has been performed in a series of 52 patients with severe pain due to malignancy. Lesions were produced either contra- or ipsilaterally to the side of the pain as well as bilaterally. Eight patients experienced good pain relief, 18 had moderate relief, and in 24 the operation did not significantly influence the pain. A second operation following recurrence of pain was rarely of value. There was a tendency towards more efficient relief of pain located in the face or in the arm and shoulder than of pain in the lower part of the body. Although contralateral lesions seem to be most effective, ipsilateral operations may also give some relief. The best results were obtained when the lesions were placed close to the wall of the third ventricle and at the level of the posterior commissure. Postmortem examination of 21 brains disclosed that the mean error in the placing of the lesions was about 1 mm. It is concluded that medial thalamotomy may be tried as a last resort in the treatment of cancer pain in selected patients with a short life expectancy.
An approach to stereotaxic radiography.
A simple approach to stereotaxic radiography, including a new method for determination of target coordinates, is described. The proposed technique may be used in combination with conventional equipment for roentgen examinations available in X-ray departments and operating rooms; the only additional outfit needed is a coordinate frame that can be attached to the patient's head. Determination of the coordinates is easily made graphically, or from a simple equation using a pocket calculator or a mini-computer.
Asystole after pacemaker placement.
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Human tumor-lymphocyte interaction in vitro. III. T lymphocytes in autologous tumor stimulation (ATS).
The T-cell nature of the responding cells in autologous tumor stimulation (ATS) was proven by (1) E-rosette formation of lymphocytes attached to tumor cells during the early period of co-cultivation; (2) blast-transformed E-rosetting cells detectable at the end of the test period (day 6) and (3) the reactivity of T-enriched lymphocyte subset and unresponsiveness of T-depleted fractions. Preparation of tumor suspensions devoid of lymphocytes made it possible to carry out cross-tests between patients. Blastogenesis with allogeneic tumors was rare. The restricted autologous nature of the reaction is a strong indication for genuine tumor-relatedness.