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Biomedical subjects

M Salcman

Publications and source records attributed to M Salcman.

121 records · Page 7Linked to original sources
PubMed1974

Motor units in cat soleus muscle: physiological, histochemical and morphological characteristics.

1. Physiological properties of motor units in the soleus muscle were studied in anaesthetized cats using intracellular stimulation of motoneurones to ensure functional isolation of single units. The muscle fibres belonging to 6 units were identified by glycogen depletion following prolonged stimulation, permitting analysis of their histochemical profiles and anatomical organization.2. The studied units in soleus were all classed as type S and were extremely resistant to fatigue during prolonged stimulation. Twitch contraction times ranged from 64 to 131 msec (mean 97.1 msec) and tetanic tensions ranged from 3.5 to 36 g (mean 10.5 g). Most units exhibited depression of twitch tension in the wake of a short high-frequency tetanus and few of the units showed any significant degree of post-tetanic twitch potentiation.3. Muscle fibres belonging to single soleus motor units were found to be scattered through territorial volumes occupying a large fraction of the total muscle volume. The available data suggest that different soleus motoneurones may innervate from less than 50 to more than 400 muscle fibres, with an average innervation ratio between 140 and 190 muscle fibres per unit.4. The results were compared with observations on type S motor units in the synergist gastrocnemius, obtained under similar conditions. The evidence suggests that soleus units are not equivalent to the type S units of the mixed gastrocnemius but rather constitute a unique population.

Adenosine Triphosphatases↗
PubMedDate not supplied

A hypothesis concerning the structural relationship between memory and emotion.

Limbic and temporal lobe structures have long been implicated as the anatomic substratum for emotion. Recent investigations have localized the processing of short term memory to a virtually identical anatomical locus. It would seem logical that the same structures subserve both functions if one assumes that the strength of the memory trace is dependent on the emotional value of the information for the organism. Under this hypothesis, the hippocampus emotionally weights sensory data as a preliminary to incorporation of such material into long term memory. It is not necessary, nor is it likely, that long term memory reside within the temporal lobe. Previous associations stored in remote memory can be accessed by the temporal lobe and these may serve to modulate the weighting of the present stimulus. Some of the functions of the temporal lobe can be modeled by a simple electronic filter; the addition of a single feedback loop to this system can account for other properties inherent in the hypothesis. The anatomical connections of the system would permit it to be an early and efficient repressor, in the pyschodynamic sense.

Animals↗
PubMedDate not supplied

Glioblastoma multiforme.

Glioblastoma multiforme is the most common primary brain tumor of adults, as well as the most malignant. Its etiology is unknown, but the tumor is thought to arise through dedifferentiation of adult astrocytes. It occurs most frequently between the ages of 40 and 60, in men more often than in women (1.5:1). Important early symptoms include subtle personality change, headache, weakness, and intellectual impairment; specific complaints and physical findings depend on the location of the lesion. The initial diagnostic test should be a CT-scan; it will detect more than 90% of malignant astrocytomas. Surgery remains the cornerstone of treatment; patients receiving radical debulking have a median survival of 8 months compared to the 3 month survival of unoperated cases. Modern neurosurgical technique, neuroanesthesia, mannitol, and corticosteroids have reduced the surgical mortality to 3%. Most patients also receive 4500 rads of whole-brain irradiation and 1800 rads to the operative site; radiotherapy increases the median survival of operated patients by 2 to 3 months. An additional small increment in survival time and some improvement in quality of survival can be achieved by nitrosourea chemotherapy; the latter is usually given as 100 mg/m2/day x 3 days of BCNU every eight to ten weeks. Experimental treatments under study include the use of radiosensitizers, the role of immunotherapy and the application of microwave-induced hyperthermia. Two-year survival remains 10% to 20%, and there are virtually no five-year survivors. An optimal combined modality treatment plan, one in which each cellular compartment of this truly multiforme tumor is effectively addressed, remains to be designated.

Adult↗
PubMedDate not supplied

Neurosurgery and clinical engineering.

Modern technology has profoundly altered the clinical practice of neurosurgery. For a wide variety of conditions, patients are being implanted with active and passive devices or treated with advanced microsurgical instrumentation. After surgery, such patients are sent to modern intensive-care units employing the latest advances in patient monitoring and computer technology. We contend that the responsibilities of the Clinical Engineer extend beyond simple installation and maintenance of equipment and systems. It is essential that he take part in the continuing education of non-technical personnel who must make use of the equipment in ways that are meaningful in the care of the patient and to the progress of clinical science. This point is illustrated by our experience with a neurosurgical intensive-care unit. It is also the thesis of this paper that the design and maintenance of increasingly sophisticated biomedical systems will benefit from the use of an interdisciplinary approach at the very inception of a project. This approach is illustrated by our current development of a multibeam microwave hyperthermia system for possible use in the treatment of brain tumors.

Astrocytoma↗
PubMedDate not supplied

Bleeding patterns in ruptured posterior fossa aneurysms: a CT study.

Computed tomography of the brains in 20 patients with acute rupture of posterior fossa aneurysms was reviewed and analyzed retrospectively. Findings were compared with those from 44 cases described in the literature and with the findings in ruptured supratentorial aneurysms. Extravasated blood was observed in 19 of 20 patients (95%); intraventricular hemorrhage (IVH) in 17 of 20 (85%); and subarachnoid hemorrhage (SAH) in 13 of 20 (65%). These values were significantly higher than those previously reported and suggest that, during the acute phase of rupture, extravasated blood may be detected with the same frequency in either infratentorial or supratentorial ruptured aneurysms. Subarachnoid hemorrhage was accompanied by IVH, prominent in the fourth ventricle and without intraparenchymal hematoma, in 11 patients (55%). This pattern is highly suggestive of ruptured posterior fossa aneurysms. Intraventricular hemorrhage without SAH was noted in five patients (25%) and specifically represented ruptured posterior inferior cerebellar artery aneurysms. Subarachnoid hemorrhage without IVH was noted in only two patients (10%).

Adult↗
PubMedDate not supplied

Transoral cervical corpectomy with the aid of the microscope.

The transoral transpharyngeal approach to the upper cervical spine is useful in symptomatic cases of chronic atlantoaxial dislocation not reducible by other means. Spontaneous healing and fusion in such patients results in an anterior deformity or gibbus which indents the ventral surface of the spinal cord. This lesion is best approached anteriorly, with the neck in a neutral or extended position. Previously reported complications of the transoral operation, especially vertebral artery laceration, can be avoided through used of the microscope. The technique is described and 2 cases are presented. Spinal stability was not disrupted in either, and cord decompression was accomplished.

Aged↗
PubMedDate not supplied

Timing of operative care in cervical spinal cord injury.

The emphasis of this review has been on bone pathology and not on neurologic syndromes. We have not discussed those rare conditions in which the neurologic deficit progresses after injury and past authors have recommended decompressive procedures. When neurologic deficits do increase, we think this is more often an indication for further diagnostic studies to see if the alignment is proper, to rule out further compression, or increase medical support if the cardiovascular status has deteriorated. When there has been a dramatic and sudden worsening of the neurologic deficit, as occurs in 3% of patients after the initial injury, the most common etiologic factor has been vascular insufficiency and further infarction of an already damaged cord. This has been substantiated by repeated diagnostic studies without compressive pathology and two pathologic specimens to support our opinion. Strict attention to the guidelines of care for spinal cord injury (1. immobilization; 2. general medical support; 3. alignment; 4. diagnostic procedures; 5. decompression only when necessary; 6. stabilization only when required) should achieve the best possible results when appropriately individualized for particular patients.

Cervical Vertebrae↗
PubMedDate not supplied

CT characteristics of a transplantable canine glioma model: preliminary kinetic analysis.

Experimental brain tumors can be produced in dogs through the intracerebral injection of 3 X 10(6) live tumor cells in either neonates or adult animals. Tumors are visible by computed tomography on day 8 postinjection. Most tumors appear as ring lesions with central lucencies and shaggy borders. By postinjection day 12, tumor volumes increase more than 10 times; the cell cycling time is about 1-3 days. The initial doubling time is about 1-2 days and corresponds to the in vitro doubling time of about 24 hr. The use of computed tomography to perform noninvasive kinetic analysis deserves further study. The transplantable canine glioma model would appear to be ideal for this purpose.

Animals↗