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Biomedical subjects

G J Dohrmann

Publications and source records attributed to G J Dohrmann.

At least 19 recordsLinked to original sources
PubMed1990

Cytokine gene expression by human gliomas.

Two glioma tumor lines and specimens from five patients with gliomas were analyzed to determine genic expression of four growth factors found in human brain. Messenger RNA encoding for interleukin-1 beta, interleukin-6, and basic fibroblast growth factor was found to be expressed in significant amounts in some of these tumors, while mRNA for interleukin-3 was found in small quantities in only the tumor lines. Multiple species of mRNA for basic fibroblast growth factor were found. Expression of growth factor genes may play a role in the growth of human gliomas.

Adult↗
PubMed1989

The transfacial approach for combined anterior craniofacial tumor ablation.

The transfacial approach to the anterior cranial fossa for tumor removal provides for excellent surgical exposure, improved postoperative appearance, and a minimum of complications. The technique is different from previously reported combined craniofacial ablative procedures in that the head and neck surgeon and the neurosurgeon approach the anterior fossa mass through the same facial incision, thus avoiding the need for a separate craniotomy incision. The formation of a vascularized nasofrontal bone flap allows for better wound healing regardless of preoperative and postoperative radiotherapy and/or chemotherapy. This report presents 42 cases in which the transfacial approach was exclusively used in a combined manner to remove nasal, paranasal sinus, and nasopharyngeal neoplasms. The transfacial technique offers a significant advantage over previously described approaches to the anterior skull base.

Facial Bones↗
PubMed1988

Molecular biology of brain tumors.

Through the technical advances in molecular biology during the past decade, important new insights into the fundamental chromosomal changes associated with brain tumors have been gained. The pace of such research is accelerating, and most of the published reports have appeared outside the neurosurgical literature. Furthermore, many neurosurgeons may not be sufficiently familiar with the terminology and techniques involved to remain abreast of the field. In this review, we discuss through specific examples of recent work on brain tumors the basic techniques of molecular biology, including the Southern and Northern blots, restriction enzyme digestion of DNA, molecular cloning of genes, and mapping of chromosomal deletions. Gene amplification and rearrangements are discussed through review of recent work on the N-myc gene in neuroblastoma and the epidermal growth factor receptor (EGFR) gene in glioblastoma. The molecular cloning of the gli gene from a glioblastoma illustrates the powerful analytic nature of these laboratory techniques and the investigative potential of a cloned gene. The concept of the "recessive oncogene" is discussed through a summary of recent work analyzing restriction fragment length polymorphisms (RFLPs) in families of patients with meningioma, acoustic neurinoma, and bilateral acoustic neurofibromatosis (BANF; NF-2). Throughout this article, emphasis is placed on ways in which molecular biology may soon affect clinical practice.

Brain Neoplasms↗
PubMed1988

Fibrinolytic activity in experimental intracerebral hematoma.

In an attempt to investigate the role of tissue fibrinolytic activity in the resolution of intracerebral hematoma, an experimental model of intracerebral hematoma was developed in the rat. The fibrinolytic activity was studied using a histochemical fibrin slide technique. A total of 59 adult male rats were studied. Twenty-nine rats were used for developing the intracerebral hematoma model via injection of autologous whole blood into the left frontal lobe; in the remaining 30 rats, the intracerebral hematomas were studied sequentially. Intracerebral hematoma formation was unsuccessful in six (21%) of 29 rats. Four rats died in the immediate postoperative period and two showed no intraparenchymal clot. Intense fibrinolytic activity was demonstrated in the blood vessel walls of the normal brain, especially in the meninges, choroid plexus, and ependymal cell layer. In the initial stages of hematoma resolution, fibrinolytic activity was not seen in the hematoma or parenchyma except in the preexisting blood vessels. However, 3 to 5 days later, fibrinolytic activity was observed in the capillary buds surrounding the hematoma and among the infiltrating mononuclear cells. This activity increased for 7 to 10 days following formation of the hematoma and decreased after 21 to 28 days. It is concluded that tissue fibrinolytic activity associated with newly formed blood vessels appears to be important in lysis of intracerebral hematomas.

Animals↗
PubMed1988

Cervical spondylosis and syringomyelia: suboptimal results, incomplete treatment, and the role of intraoperative ultrasound.

The pathophysiology of cervical spondylotic myelopathy and syringomyelia is incompletely understood. Only 50-60% of the former group of patients and only 30-40% of the latter group of patients show long-term improvement. One possible cause for this might be continued anterior compression of the spinal cord in the former and incomplete drainage of the fluid-filled cavities in the latter. Intraoperative ultrasound imaging can be done in the operating room (4-6, 16-18) and can identify whether an adequate decompression has been done in patients with cervical spondylotic myelopathy and whether there has been complete drainage in shunting of patients with syringomyelia. Intraoperative ultrasound imaging aids the neurosurgeon in checking to see if he did what he set out to do. It is useful in operative procedures for cervical spondylotic myelopathy and syringomyelia.

Cervical Vertebrae↗
PubMed1987

Oxidative metabolism and glycolysis in benign brain tumors.

Glucose utilization in vivo and hexokinase activity and mitochondrial oxygen consumption in vitro were measured in a series of human brain tumors. Several relatively slow-growing tumors appeared to have depressed electron-transport activities coupled with a compensatory elevated glucose utilization. These data suggest that a decrease in oxidative metabolism and a corresponding increase in glycolysis are not necessarily correlated with malignancy in certain human brain tumors.

Brain Neoplasms↗
PubMed1986

The tortuous or kinked carotid artery: pathogenesis and clinical considerations. A historical review.

The significance and management of cervical carotid artery tortuosity are controversial. One hundred eighteen cases of angulation of the common carotid artery and over 800 cases of elongation of the internal carotid artery have been reported. The etiology, presentation, diagnosis, and treatment of each entity are reviewed. Angulation of the common carotid artery is often managed conservatively. For clarity, elongations of the internal carotid artery should be classified as either tortuosities or kinks. Some patients with kinks of the internal carotid artery will have episodes of cerebrovascular insufficiency related to the position of their heads. Such patients merit thorough diagnostic evaluation. When other etiologic factors have been eliminated, patients in this group may benefit from a surgical procedure directed at the vascular abnormality. Applicable surgical techniques are discussed.

Carotid Arteries↗
PubMed1986

Respiratory patterns in human brain tumors.

It has been recognized for some time that malignant cells have a diminished respiratory rate coupled with an excessive rate of aerobic glycolysis. Subsequent studies indicated, however, that this pattern was neither unique to malignant tumors nor an essential characteristic of all varieties of cancer. In attempting to synthesize the data on oxygen consumption of human brain tumors, it is difficult to relate activity to malignancy, and the integrity of the mitochondrial electron transport chain has not been systematically examined. In this study, oxygen consumption was measured using a whole cell mixture and subsequently with isolated mitochondria prepared by routine differential centrifugation from a variety of human brain tumors. It is clear from these data that low oxidative respiration is not uniquely characteristic of malignant tumors, but that a number of benign tumors such as meningiomas and pituitary adenomas display very low levels of oxygen consumption. Many of these tumors have normal respiration, with isolated mitochondria using substrates that enter at different points in the electron transport pathway. However, several of the tumors in this series showed defects in respiration at various points in the electron transport pathway. These data suggest that both benign and malignant brain tumors have depressed respiratory capacities secondary to either a decrease in mitochondria per cell or defects in electron transport activities.

Adenoma↗
PubMed1985

Astrocytomas in childhood: a population-based study.

A population-based study of astrocytomas occurring in children is reported. A population-based study eliminates referral bias and the bias of a series based on the experience of a given medical center or a particular surgeon. In a 42-year period, 179 such cases were diagnosed. The average age at diagnosis was 8.9 years. Over one-half of the astrocytic tumors were located in the cerebellum. A peak in the number of astrocytomas was noted between 1965 and 1970. Cumulative probability of survival of children with intracranial astrocytomas at 6 months and at 1, 2, and 5 years was 0.824, 0.752, 0.732, and 0.667; by 10 years and 20 years the cumulative probability of survival had fallen to 0.607 and 0.538. The shortest survival was observed with brainstem tumors, with an average survival of 19 months. Longer survivals were noted with tumors of the cerebral hemispheres: 0.779, 0.748, 0.678 and 0.628 at 1, 2, 5, and 10 years, respectively. The longest survivals were in those children with cerebellar astrocytomas: at 1 year they had an 0.837 probability of survival and at 20 years, 0.675.

Adolescent↗
PubMed1985

Thoracic disc herniation. Improved diagnosis with computed tomographic scanning and a review of the literature.

Thoracic disc herniation is uncommon. One of the main problems in the treatment of thoracic disc herniation has been the lack of accuracy of diagnostic tests. Now, with the use of computed tomographic scanning with and without metrizamide in the subarachnoid space, this accuracy has greatly improved. Computed tomography scanning can demonstrate the type and level of the lesion even when the myelographic study is negative. We have reviewed 280 cases; a peak incidence was noted in the fourth decade with 75% of the protruded discs occurring below T-8. Back pain was the most common presenting symptom followed by sensory disturbances. By the time of diagnosis, 70% of the patients had signs of spinal cord compression. A small group of patients could be identified that invariably had a good prognosis. They had a history of trauma, symptoms lasting less than a month, and soft disc herniation. Regarding the results of surgical treatment, there was a success rate ranging from 57% for decompressive laminectomy to over 80% for the posterolateral, lateral, and transthoracic approaches.

Female↗
PubMed1985

The spine and spinal cord during neurosurgical operations: real-time ultrasonography.

Intraoperative ultrasound scanning of the spinal cord and spine was performed during 36 operations in 35 patients. The technique allows neurosurgeons to evaluate an operative procedure during the operation. Effectiveness of shunt placement in syringomyelia can be detected and the completeness of tumor or disk removal can be determined. Precise locations for biopsy of intramedullary lesions can be made. Periodic motion of the spinal cord at the cardiac rate was also detected. This motion was usually due to transmitted pulsations from the anterior spinal artery and appeared to be most pronounced when the artery was compressed between a mass and the spinal cord. This finding refutes the commonly held idea that spinal cord motion implies that the cord is free within the thecal sac.

Heart Rate↗
PubMed1985

Efficacy of intraoperative US for evaluating intracranial masses.

The efficacy of intraoperative neurosurgical ultrasound (US) scanning was determined in studies of 191 lesions (186 patients). US was deemed to have played a useful role in operations on 101 (53%) of these lesions, including 66 (49%) of the 136 brain tumors. The main utility of US imaging was in locating subcortical masses, but it also proved useful in identifying residual tumor after resection; locating cysts within tumors; delineating surrounding vascular structures; and locating subcortical cysts, hematomas, arteriovenous malformations, and inflammatory masses or abscesses. In light of these findings, US study appears to have a place in many intracranial operations.

Brain Diseases↗
PubMed1985

Evaluation and treatment of cerebral ischemia. Carotid endarterectomy and extracranial-intracranial bypass.

Patients with cerebral ischemia comprise an extremely heterogeneous group that makes analysis of treatment extremely difficult. Given the wide range of findings in the literature, one may select specific reports to justify a predetermined viewpoint. The study of Easton and Sherman has elicited a disproportionate amount of attention. Of the thousands of reported patients in the literature, this study of 228 patients with high postoperative morbidity and mortality has regrettably been cited often as the potential representative of surgical outcome in community hospitals. Undoubtedly, surgical skill varies and may affect results. Not all studies, however, support the contention that such procedures can only be performed adequately by surgeons who frequently do such operations. Most importantly, this study should redraw our attention to the fact that the success of the individual surgeon must be evaluated for any given procedure. With proper selection of patients, both carotid endarterectomy and EC-IC bypass procedures have proved to be safe and effective. In general, technical advances have heralded surgical results that appear to be superior to medical management, or no treatment, in a wide range of patients with cerebrovascular disease. Surgical results can only be evaluated when a procedure is fully developed technically and a large number of cases are accumulated. For carotid endarterectomy, and more recently EC-IC bypass, the necessary information is becoming available. However, the classification of patients to which these procedures should be applied has lagged behind. Given the variability in patients with cerebrovascular disease, this is somewhat understandable. Properly controlled studies would necessarily be unrealistically large. However, the technology and subsequent data that should be developed throughout the next decade will provide us with important information about brain ischemia and metabolism. This new technology should allow us to more completely define the exact nature of ischemic events in the individual patient. This will lead to better classification of patients and, ultimately, will improve patient selection for any methods of treatment, either medical or surgical.

Aged↗
PubMed1985

Herniated thoracic disks.

Thoracic disc herniation is uncommon. An incidence of 0.25 to 0.75 per cent of protruded disks are in the thoracic region. A peak incidence is noted in the fourth decade with 75 per cent of the protruded disks occurring below T8. Pain is the most common initial symptom, present in 57 per cent of the cases, followed by sensory disturbances and motor involvement. By the time of diagnosis, 90 per cent of the patients have signs of spinal-cord compression. Although myelography has been considered the test of choice, 8 per cent false negative results and a correct preoperative diagnosis of 56 per cent has been reported. Now, with CT scanning with and without metrizamide, more accurate diagnoses can be achieved, even with cases in which myelography is negative. There has been a considerable improvement in the surgical treatment of herniated thoracic disks with over an 80 per cent rate of success for surgical approaches other than the posterior approach (decompressive laminectomy). An early and accurate diagnosis, coupled with improvement in the surgical approach, offers a much better prognosis for patients with thoracic disk herniation.

Adolescent↗
PubMed1985

Dynamic intraoperative imaging and instrumentation of brain and spinal cord using ultrasound.

Intraoperative real-time ultrasound imaging in the neurosurgical operating room is most useful in localizing, characterizing, and guiding the instrumentation of lesions of the brain and spinal cord. In the future, more and more operative procedures will be done using intraoperative ultrasound guidance. The ultrasound scanner, as developed for neurosurgery, will become another instrument in the neurosurgeon's armamentarium.

Biopsy↗
PubMed1984

Colloid cysts with and without ventriculomegaly: role of intraoperative real-time ultrasound.

Intraoperative real-time ultrasound was used to assist localization and surgical removal of colloid cysts in patients without ventriculomegaly. In the most commonly used surgical approach for removal of colloid cysts, dilated lateral ventricles can expedite the localization of lesions because, once entered surgically, a dilated ventricle offers more space near the foramen of Monro in which to work. Additionally, the enlargement of the foramen of Monro, seen with hydrocephalus, provides greater accessibility to the colloid cyst. In patients with symptoms related to the colloid cyst. In patients with symptoms related to intermittent obstruction of cerebral fluid flow but with normal-sized ventricles, the precise localization of the foramen of Monro and colloid cyst is more difficult and may result in unnecessary exploration/resection of brain. Using intraoperative ultrasound, the colloid cyst and adjacent anatomic structures can be clearly visualized regardless of ventricular size. Intraoperative ultrasonography has a unique role in the operative treatment of patients with colloid cysts and nondilated ventricles.

Adolescent↗