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H Dietz

Publications and source records attributed to H Dietz.

At least 37 records · Page 2Linked to original sources
PubMed1996

Ultrastructural changes in the blood-brain barrier in rats after treatment with nimodipine and flunarizine. A comparison.

The idea of using induced hypertension to treat the symptomatic ischaemia resulting from vasospasm after subarachnoidal hemorrhage, and the effect of this therapy on the blood-brain barrier, is checked in animal experiments. This therapy is combined with the application of nimodipine, which is recognised as the standard medication for prophylaxis of vasospasm. The effects of the induced hypertension combination with Nimodipine and in combination with another calcium antagonist, Flunarizine are compared. Seventy-four narcotised rats, one group with 22 animals treated with Nimodipine and 22 with placebo, and a second group 20 animals treated with Flunarizine and 10 with placebo, are evaluated. The blood pressure is raised to 150-180 mmHg by i.v. application of norfenephrine and measured continuously. The standard tracer, horseradish peroxidase, is applied as indicator for the blood-brain barrier function. 15 minutes later the experimental animals are exsanguinated by perfusion with saline, then perfused with Karnovsky's solution. After removal, the brains are stained for peroxidase to visualise extravasation of the horseradish peroxidase, and after evaluation of the results each brain is assigned to its experimental group. In the Nimodipine group, a significant accumulation (p < 0.001) of perivascular deposits of peroxidase reaction product were found, these were not found in the placebo group. The Flunarizine group does not differ from its placebo group in the number of extravasates, and thus, with respect to protein extravasation, appears better than the Nimodipine group. In electron micrographs of the extravasates one sees intact tight junctions and a neuroendothelial transport, and also vesicles, filled with horseradish peroxidase in the endothelium, the muscle cells, and the brain parenchyma, which arise from pinocytosis. The vesicles, which transport the high-molecular-weight protein, horseradish peroxidase, also transport other proteins and can, therefore, cause a brain edema. It follows from these morphological results that Nimodipine can disrupt the blood brain barrier function and can, therefore, also interfere with cerebral autoregulation, which depends on the resistance of vessels.

Animals↗
PubMed1996

A proposed modification of the Wada test for presurgical assessment in temporal lobe epilepsy.

We report experience with a modification of the Wada test used before temporal lobe resection in patients with drug-resistant epilepsy. Our procedure consists of injection of amytal via a microcatheter into the anterior choroidal artery or the P2 segment of the posterior cerebral artery and simultaneous presentation of verbal and figural memory test material before, during and after the injection. Pros and cons of the modification and inherent shortcomings of the amytal test are discussed on the basis of the results in ten patients.

Adolescent↗
PubMed1996

[Midline and vertex epidural hematomas: clinical aspects, surgical indications and therapy].

Within a group of 315 epidural haematomas treated surgically 8 (2.5%) were located within the midline or at the vertex. The clinical symptoms may be small in frontally located haematomas. Paraparesis is caused by a haematoma localized at the vertex. The latter may be misinterpreted as a spinal trauma. The recognition of the hyperdense blood within the last slices of normal CT scans needs experience. It has been misinterpreted as hyperostosis of the skull. We present a group of eight personal cases. The sagittal skull suture was fractured in seven patients. One patient already had an 11-month history. Four cases were primary and had not been recognized. The prognosis depends on concomitant primary brain injuries. Early diagnosis with operative treatment given the best chance. Polytraumatized patients with concomitant injuries die. Slowly developing haematomas do not require acute surgery by in experienced surgeons. Sagittal sinus laceration must be treated by experienced neurosurgeons. It can be closed by suturing the dura to the bone with implanted collagen. In subacute cases the stiffness of the dura allows no normalization of the dura position. A dural graft is necessary for repositioning.

Adolescent↗
PubMed1996

The role of N-actylglucosaminyl-1,6 anhydro N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid-D-alanine for the induction of beta-lactamase in Enterobacter cloacae.

The mechanism of beta-lactamase induction in Enterobacter cloacae which is linked to the peptidoglycan recycling, was investigated by HPLC analysis of cell wall fragments in genetically defined cells. It is demonstrated here that the transmembrane protein AmpG transports not only the precursor muropeptide of M-tripeptide (N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid), the D-tripeptide (N-actylglucosaminyl-1,6 anhydro N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid), but also that of M-tetra-peptide (N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid-D-alanine), the D-tetrapeptide (N-actylglucosaminyl-1,6 anhydro N-acetylmuramyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid-D-alanine), into the cytoplasm. These findings indicate that probably also M-tetrapeptide and D-tetrapeptide are signal muropeptides for beta-lactamase induction. In fact, D-tetrapeptide, not D-tripeptide, increases upon imipenem treatment.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1996

[Regional cerebral blood circulation and cerebrovascular reserve capacity as indications for in vascular reconstructive surgery].

Effect of Extra-Intracranial Bypass and Carotid Thrombendarterectomy. The causal treatment of cerebral ischemia requires an exact analysis of the basic deficit of cerebral blood flow. Cerebral ischemia can be the result of hemodynamic insufficiency or frequently a consequence of thromboembolic event. The distinction of both forms of ischemia is possible only by dynamic measuring of regional cerebral blood flow and evaluation of the cerebral vascular reserve capacity. This allows to select of a small group of patients who suffer from carotid occlusion or a combined occlusion with stenosis of the contralateral side, where a characteristic disturbance of the cerebrovascular reserve capacity can be proved. By performing an extra-intracranial bypass, the cerebral collateral blood supply can be improved in order to reduce the risk of stroke. In this study 26 patients received an extra-intracranial bypass. 7 weeks after surgery a normalization of the limited cerebrovascular reserve capacity was observed. With regard to carotid stenosis, thrombendarterectomy was conducted in 63 patients. Although the cerebrovascular reserve capacity had not been impaired in this group preoperatively, a further increase was observed following thrombendarterectomy. It is indisputable that the indication for thrombendarterectomy is aiming towards elimination of the source of emboli. However, our results indicate that thrombendarterectomy has an additionally positive hemodynamic effect.

Adult↗
PubMed1996

Computed tomographic criteria and survival rate for patients with acute subdural hematoma.

OBJECTIVE: Computed tomographic data from 174 patients with acute subdural hematoma were analyzed statistically to identify parameters that could be evaluated independently of clinical and neurological status to estimate outcome. METHODS: This retrospective study was made necessary by the fact that the patients admitted usually had been treated with intubation, sedation, and artificial ventilation, which precludes neurological examination. RESULTS: In surgically treated patients, the hematoma thickness ranged from 5 to 35 mm and the midline shift was 0 to 33 mm. In 81 patients (46.6%), the hematoma thickness was greater than the midline shift; in 24 patients (13.8%), the hematoma thickness equaled the midline shift; and in 69 patients (39.6%), the midline shift exceeded the hematoma thickness. Of the patients, 52% died after surgery, for 29% we obtained good or satisfying results, and 19% were in poor condition after therapy. The Kaplan-Meier survival analysis proved that the survival rate was only 50% for a hematoma thickness of approximately 18 mm and a midline shift of 20 mm. The survival function dropped markedly for midline shifts of more than 20 mm and converged to 0% for midline shifts of more than 25 mm. If the midline shift exceeded the hematoma thickness by 3 mm, the survival function was 50%; when the midline shift exceeded the hematoma thickness by 5 mm, the survival function was 25%. The Glasgow Outcome Scale scores were correlated significantly with these parameters. The parameters, which are the measured hematoma thickness, the midline shift, and the difference between the hematoma thickness and the midline shift, allow robust/adequate estimation of survival function and outcome for patients suffering from acute subdural hematoma. CONCLUSION: Based on these data, indications for surgery could be assessed by means of video conferencing, i.e., without personal examination of the patients.

Acute Disease↗
PubMed1996

Location of N-acetylmuramyl-L-alanyl-D-glutamylmesodiaminopimelic acid, presumed signal molecule for beta-lactamase induction, in the bacterial cell.

Using a chromatographic method for the isolation and detection of periplasmic and cytoplasmic muropeptides avoiding radioactive labeling, we found that in the ampD-negative strain JRG582 the anhydromuropeptide N-acetylmuramyl-L-alanyl-D-glutamylmesodiaminopimelic acid (anhMurNAc tripeptide) accumulates not only in the cytoplasm but also in the periplasm. Simultaneously JRG582 carrying the Enterobacter cloacae genes ampC and ampR, which are necessary for the induction of beta-lactamase expression, overproduces beta-lactamase. We confirmed that the transmembrane protein AmpG transports a precursor muropeptide into the cytoplasm and that the formation of the anhMurNAc tripeptide takes place in the cytoplasm. anhMurNAc tripeptide can then be secreted into the periplasm. Therefore, the amount of anhMurNAc tripeptide in the cytoplasm is reduced not only by AmpD but also by transport out of the cell.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1996

[Inhibition of angiogenesis and growth of malignant gliomas in the athymic nude rat model: immunotherapy against "basic fibroblast growth factor"].

An important feature of malignant progression in human gliomas is increased polymorphism of tumor cells associated with karyotypic heterogenity and a variety of secondary changes, one of which is increased angiogenesis. The capability of brain tumors for angiogenesis most probably is the earliest sign for malignancy in 95% of cases and occurs before typical changes of histology appear. Malignant brain tumors are known to produce several angiogenic growth factors. One of the most potent of these factors is the basic fibroblast growth factor (bFGF). In an experimental study human U87 MG glioma cells (2.10(5) cells/50 microliters) were implanted through a burrhole into the cerebral cortex in a group of 25 nude rats. After 3 weeks we found a reproducible extensive tumor growth with extensive neovascularization. Immunohistochemical evaluations proved a high expression of bFGF in the tumor. A parallel group of xenotransplanted rats were treated with 33 micrograms of rabbit anti-bFGF antibodies during tumor cell implantation. Thereafter, the same dosages of antibodies were administrated intracranially twice a week for 3 weeks. We found a significant inhibition of tumor vascularization and growth compared to other groups who had no treatment or who received irrelevant immunoglobulins or saline as a control. Our results indicate that inhibition of tumor angiogenesis might contribute to inhibition of tumor growth in malignant gliomas.

Animals↗
PubMed1995

In vivo inhibition of angiogenesis and growth of the human U-87 malignant glial tumor by treatment with an antibody against basic fibroblast growth factor.

The effectiveness of in vivo suppression of neovascularization and growth of malignant glial tumors by in situ administration of an antibody directed against basic fibroblast growth factor (bFGF), a strong mitogen for cells of mesodermal origin, was tested. One hundred fifty congenitally athymic nude rats (han rnu/rnu) were implanted intracerebrally with U-87MG tumor cells, known constitutive producers of bFGF. The animals were randomly assigned to six groups of 25 animals each. Animals were treated by in situ application of saline (Group F), control antibody (Group D), or polyclonal anti-bFGF antibody (Group B). In additional groups a putative effect on tumor growth caused by the treatment application device itself (between growth control Groups A and E), and the effect of heat-inactivated tumor cells (negative control Group C) were tested. After 3 weeks of treatment, tumor progression and degree of neovascularization were morphometrically recorded. In the untreated Groups A and E massive tumor growth was recorded, consisting of 19.9% +/- 0.4% and 27.1% +/- 0.5%, respectively, of the total brain cross-sectional area. In Group C, no tumor growth occurred. In control Groups D and F tumor progression consisted of 18.6% +/- 0.4% and 18.5% +/- 0.4%, respectively, of the total brain cross-sectional area; whereas in the anti-bFGF treated Group B, significantly smaller tumor masses measuring 7.2% +/- 0.1% were recorded. New blood vessels were located both peritumorally and intratumorally and defined as numerical density and area fraction (number/area and area/area). Significantly more new blood vessels were found in Groups A, D, E, and F, ranging from 41,380/mm2 +/- 464/mm2 to 53,442/mm2 +/- 150/mm2 peritumorally and 51,846/mm2 +/- 495/mm2 to 64,660/mm2 +/- 183/mm2 intratumorally than in the anti-bFGF treated Group B, which numbered 8220/mm2 +/- 225/mm2 peritumorally and 16,554/mm2 +/- 236/mm2 intratumorally. The authors conclude that treatment with anti-bFGF antibody is effective in inhibiting tumor-induced angiogenesis and correlated tumor progression. However, owing to the character of the experimental system used, one cannot exclude the possibility that application of the specific anti-bFGF antibody also counteracts device-induced neovascularization. The authors suggest that combined surgical excision and adjuvant immunotherapy of tumors such as glioblastoma and other malignant brain tumors that express bFGF might prevent tumor recurrence.

Animals↗
PubMed1995

[Changes in regional and local brain circulation in patients with subarachnoid hemorrhage due to ruptured aneurysm].

It is well known that cerebral blood flow (CBF) is altered corresponding to the severity of the subarachnoid hemorrhage (SAH) in different extents. The extent of CBF reduction and its regional accentuation is regarded as a pathophysiological correlation of clinical conditions. Therefore, we agree that CBF of patients in grade IV+V (Hunt and Hess) are clearly lower than in grade I+II. There are quite different results in grade III. Disturbance of consciousness and/or neurological deficits, as described in the definition of grade III, can be a consequence of different kinds of CBF changes. 45 Xe-CT studies were performed on 19 patients (mean age 44 +/- 14 years) after SAH. 8 patients were of grade I+II, 7 of grade III, and 4 patients of grade IV+V. The studies were performed preoperatively, at a time of clinical change, and before discharge. The evaluation of flow-maps was done by measuring 15 regions per hemisphere. Mean CBF data were evaluated in each area. To show the CBF differences between both hemispheres within each group of patients, a difference index (%) was calculated. The results demonstrated a mean CBF reduction in nearly all regions from grade I+II to grade III up to grade IV+V. The mean CBF reduction between grade I+II and grade III was 10% for gray and 20% for white matter (p < 0.05). On the other hand the difference index of gray matter in grade III with 17% is significantly higher than in grade I+II. For the white matter there was no significant side difference. Our findings demonstrate a visually evaluable pattern of CBF corresponding to grade I+II, grade III, and grade I+V. Intention of this study was to show a correlation between clinical conditions of patients after SAH and the CBF changes by the use of Xe-CT method.

Adult↗
PubMed1993

[Spinal seeding metastasis of a WHO grade III oligo-astrocytoma].

3 1/2 years after two operations and radiation therapy of a biparietally, parasagittaly localised grade III oligoastrocytoma, a 34-year-old patient developed symptoms of the spinal cord. By performing magnetic resonance tomography and laminectomy, multiple metastases of the anaplastic part of the primary tumour could be identified. Spinal seedings of a tumour of this grading are even rarer than those sporadically reported on corresponding complications of a multiform glioblastoma. Risk factors for the development of such a complication are youth of the patient, primary site of the tumour near the midline and anaplastic parts of the tumour in adults. If such a constellation exists, one should definitely consider the possibility of a spinal seeding in a grade III glioma, especially because in these younger patients thus would be of greater relevance for therapy than in patients with multiform glioblastoma.

Adult↗
PubMed1993

[Morphologic characteristics and ATPase activity in permeabilized epididymal bull sperm].

The treatment of bull spermatozoa from epididymal cauda with 5 micrograms digitonin per microliters cells led to the destruction of the plasma membrane which was shown by electron microscopy. Structural changes of mitochondria and of the axoneme were not found. The functional intactness was maintained. The plasma membranes of hypotonically treated spermatozoa were permeable for succinate and the mitochondria showed a diminished functional intactness. For the total ATPase activity of digitonin-treated cells, mainly representing the dynein ATPase, a maximal activity of 20.3 nmol ATP x min-1 x microliters cells-1 (mean +/- S.D.; n = 8) and an apparent half saturation constant of 0.29 mM ATP were determined. The portions of Na(+)-K(+)-ATPase and mitochondrial ATPase in the total ATP-splitting activity were found to be less than 15%. In comparison to the capacity of mitochondrial ATP production, the maximal activity of ATP consuming reactions amounted to about 70%. These results support findings that the ATP turnover of spermatozoa is more limited by the ATP consumption than by the ATP production.

Adenosine Triphosphatases↗
PubMed1993

The effect of mannitol and nimodipine treatment in a rat model of temporary focal ischemia.

Male Sprague Dawley rats were anesthetised with Xylazine and Ketamine intraperitoneally. After a lateral craniotomy the cerebral inferior vein was ligated and a very small clip (Biemer clip) was placed on the MCA near its origin for 1 hour. This procedure induced a focal infarction in 100% of the rats. After removal of the clip the lumen of the MCA was patent. The study was divided in 3 randomized groups (control group n = 15; Nimodipine group n = 11, treatment 30 micrograms/hour/kg body-weight; Mannitol group n = 15, treatment 5.4 ml/hour/kg body-weight). Besides heart-rate, ECG and blood pressure we measured the extracellular potassium and calcium concentration with ion-selective microelectrodes; the ICBF was estimated by laser-doppler-flowmeter. The MCA was clipped for 1 hour. After 1 hour of reperfusion the brain was fixated and the volume of infarction was measured by serial slices. Nimodipine or Mannitol treatment started 5 min before clipping the MCA. In rats with Nimodipine treatment the extracellular calcium starts at a significantly higher level (2.3 +/- 0.5 mmol/l) and the decrease during ischemia remains above a level of 1.2 +/- 0.2 mmol/l. The increase in potassium during ischemia and Nimodipine (calculated in change of concentration/time [dc/dt]) is significantly slower than in the control group. In contrast to the post-ischemic hyper- and hypoperfusion in the control group the reperfusion in the Mannitol group is nearly normal. In the control group the infarction volume is 20% of the brain, in the Nimodipine group 15% and in the Mannitol group only 11%. The calcium antagonist Nimodipine and the free-radical scavenger Mannitol therefore promise to be a way to treat or prevent temporary focal cerebral ischemia.

Animals↗
PubMed1992

Cerebral blood flow and intracranial pressure during experimental subarachnoid haemorrhage.

The relationships of intracranial pressure (ICP), systemic blood pressure (SBP) and cerebral blood flow (CBF) during experimental subarachnoid haemorrhage were investigated in cats. Continuous monitoring of regional cerebral blood flow (rCBF) was done by a thermal diffusion method using a Peltier stack. During haemorrhage ICP rose within 5.4 +/- 0.97 minutes from 10.5 +/- 4.9 to 176.1 +/- 27.8 mmHg. This strong increase of ICP resulted in a temporary arrest of cerebral circulation. The Cushing response during the haemorrhage could not improve the cerebral circulation, but in contrast caused a further increase of ICP. After the haemorrhage the cerebral blood flow normalised within minutes. It is concluded, that the Cushing response during a subarachnoid haemorrhage should be regarded as a deleterious rather than a beneficial mechanism.

Animals↗
PubMed1992

Combined orbito-frontal, sub- and infratemporal fossa approach to skull base neoplasms. Surgical technique and clinical application.

Neoplasms located along the antero-lateral skull base, with probable involvement of the orbit and with extension into the pterygoid and/or infratemporal fossa can usually not be sufficiently exposed using standard neurosurgical or otosurgical approaches, which is why combined approaches to these skull base targets have been developed in the recent past. In this report we describe our experience, using a combined orbito-frontal, sub- and infratemporal fossa approach which, starting with a pre-auricular incision and a standard pterional craniotomy, is extended to an extensive osteoplastic enbloc resection of the orbito-zygomatic area allowing for direct visualisation of the antero-temporo-lateral skull base from the orbital cavity to the depth of the infratemporal and pterygoid fossa. The surgical technique as well as the clinical experiences accumulated with this approach are described.

Chordoma↗
PubMed1992

Grading of supratentorial arteriovenous malformations on the basis of multivariate analysis of prognostic factors.

The case histories and angiograms of 93 consecutive patients who underwent surgery for arteriovenous malformations were analyzed retrospectively to find clinical and radiological prognostic factors influencing the outcome. A stepwise multiple regression was performed as follows. All radiological data such as size, location, and feeding and draining vessels as well as the clinical data such as age, sex, clinical grade on admission were introduced into the model and tested whether they contributed significantly to the prediction of the outcome which was the target variable. If so they were retained, otherwise eliminated. By this procedure the following features were identified as significant prognostic factors which adversely influence the outcome: poor clinical grade, feeding vessels from the A 1-segment and the anterior communicating artery, feeders from the M 1-segment, feeders from the Rolandic branches of the middle cerebral artery, a shunt through the anterior communicating artery. Neither the presence of a particular draining vein nor the type of the venous drainage when divided into superficial or deep had an influence on the outcome. Nor was the size of the lesion of significant importance. The bearing of these findings on the value of established grading systems is discussed and a new grading system is proposed.

Female↗
PubMed1992

The results of surgery for intracerebral hematomas.

Our retrospective study included 104 patients (28 female and 76 male) with intracerebral bleeding, treated between 1978 and 1988 in the Neurosurgical Clinic of the Medical University in Hannover. The average age was 43 years. 53 patients presented with traumatic intracerebral bleedings, and 51 with spontaneous hematomas. 31 patients with spontaneous hematomas were operated: among these a good or satisfactory result was obtained in 19 patients, and 12 died. Of the 20 non-operated patients, a good or satisfactory result was achieved in 10. 31 patients were operated in the group with traumatic hematoma, of these 22 had a good or satisfactory outcome and 9 patients died or had an unsatisfactory result. Of the 22 non-operated patients, 13 died and 9 achieved a good or satisfactory result. In the stratified Chi2-Test the effects of the operation were not found to be significant, with 0.1 less than p less than 0.25 for spontaneous, and 0.25 less than p less than 0.05 for the traumatic hematomas. There is a trend in favor of the operation in certain cases.

Adult↗