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Impaction‐graphite furnace atomic absorption spectrometry (I‐GFAAS) has been used to directly and simultaneously determine cadmium, chromium, lead, and manganese in the smoke or plume from burning crude oil in laboratory‐controlled conditions. Concentrations in the low ng/m3 can be determined for all four metals. Cadmium and lead appear in the smoke in the first 30 sec of the burn whereas up to 120 sec is required for all the chromium and manganese to be found in the smoke.

The simultaneous determination of cadmium and lead in cigarette smoke was achieved using a unique impaction-graphite furnace atomic absorption spectrometry system (I-GFAAS), and in inert cigarette parts (whole, tobacco, filter, and paper) using conventional graphite furnace atomic absorption spectrometry (GFAAS) following digestion using a previously established microwave digestion method. Results showed that in both the whole cigarette and the smoke there was about a factor of two in lead compared to cadmium concentrations, typically 17.56 compared to 31.94 mg/g for whole cigarette and 13.41 to 25.72 ng/m3 for cigarette smoke.

OBJECTIVE : An approach to transnasal transsphenoidal debulking of pituitary tumors using endoscopic guidance is presented. METHODS : Technical details of this approach using an endoscope inserted through one nostril and operating instruments inserted through a submucosal tunnel created via the other nostril are discussed. RESULTS : Ten patients who had operations are tabulated. Illustrative cases are presented. CONCLUSION : Endoscopic debulking of pituitary tumors can provide good results with minimal operative morbidity.

The design, operating characteristics, and preliminary evaluation of an improved impaction-graphite furnace system, based on a theoretical study of particle size collected, are presented. After direct collection, the graphite furnace from the system is inserted in an atomic absorption spectrometer for analysis by simultaneous multielement atomic absorption spectrometry. This system has the potential for the direct and near real-time (few minutes) determination of metals in aerosols. The system has been preliminarily evaluated using aqueous solutions of chromium, and has then been applied to the determination of cadmium, chromium, lead, and manganese in cigarette smoke. Results show an increase ranging from almost five (lead) to sixteen (cadmium) over background levels.

Prolactin (PRL) Levels are frequently elevated in patients with non-PRL-secreting adenomas or other intrasellar and parasellar diseases ("pseudoprolactinomas"). This phenomenon is believed to result from a loss of dopaminergic inhibition on pituitary lactotrophs and is known as the "stalk-section effect." Using magnetic resonance imaging scans and a high-magnification sella technique, we measured a number of parameters indicative of the disruption of normal sellar structures. The investigator was blind to the patient's diagnosis and PRL level while collecting the data. Parameters measured were the tumor size, the angular deviation of the pituitary stalk, and the degree of compression of the pituitary stalk. Measurements were obtained from 44 patients with pathologically confirmed tumors that had no immunohistochemical reactivity to PRL. PRL levels were often higher than expected. Four patients (9%) had a PRL level of more than 150 ng/ml, and three patients (7%) had a PRL level of 200 ng/ml or more. One patient with a plasmacytoma eroding the sella floor had a PRL level as high as 504 ng/ml. There was no significant correlation of PRL level and the degree of pituitary stalk compression, stalk deviation, or tumor size. PRL levels were found to be markedly elevated in some patients with a tumor causing little distortion of the pituitary stalk. Conversely, PRL levels were often normal despite evidence of massive distortion of the stalk. Therefore, magnetic resonance imaging evidence of pituitary stalk distortion cannot be used to determine the diagnosis of prolactinoma versus pseudoprolactinoma in most cases.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVE The purpose of this report is to discuss the technical aspects of operating on colloid cysts through a transventricular approach, with rigid endoscopes. METHODS Twelve patients underwent 14 endoscopic operations in attempts to treat their colloid cysts. All patients were symptomatic, with headache being the most common complaint (8 of 12 patients). Six patients in this series exhibited enlarged ventricles associated with their colloid cysts. Using rigid endoscopes of < or =3.5-mm diameter, the cysts were inspected and fenestrated. Both hard and soft cyst contents were evacuated, and then the walls of the cysts were coagulated inside and outside. External ventriculostomy tubes were usually placed. Technical obstacles to successful completion of endoscopic colloid cyst surgery are discussed. RESULTS For 11 of the 12 patients, the colloid cysts could be treated via an endoscopic approach. The mean follow-up time was 173 weeks, and the median follow-up time was 125 weeks. For the 12th patient, bilateral scarring of the foramina of Monro precluded direct surgery; therefore, a septostomy was performed and a ventriculoperitoneal shunt was placed. CONCLUSION Endoscopic transventricular surgery should be considered for the treatment of colloid cysts.

Metastasis to the brain occurs in 20%–40% of cancer patients.1 About 20% of these metastases are located in the posterior fossa, cerebellum, and brainstem. Metastatic disease to periventricular brain tissue can obstruct the flow of cerebrospinal fluid (CSF) produced in the ventricles to the subarachnoid space where it is normally absorbed by arachnoid granulations. This typically causes an obstructive or non-communication hydrocephalus. A shunt has been customarily placed to drain CSF from a lateral ventricle through a pressure regulating valve and into the atrium or peritoneal or pleural cavity. Even though this technique has been successful in relieving the hydrocephalus, it has about a 50% chance of infection or failure from blockage.2 Another option for the treatment of obstructive hydrocephalus is third ventriculostomy, a minimal invasive endoscopic neurosurgical procedure. In performing third ventriculostomy, a hole is created in the floor of the third ventricle, allowing CSF inside the ventricle to drain out to the CSF space surrounding …

Mesial temporal sclerosis, otherwise known as hippocampal sclerosis, is the most common entity associated with medically intractable temporal lobe epilepsy. The neuronal loss and gliosis of the hippocampus that is pathologically characteristic of this disorder is thought to serve as an epileptogenic substrate. Accurate identification and localization of this pathology is crucial before surgery is considered to potentially cure medically intractable seizures. Magnetic resonance imaging plays a central role in the presurgical work-up. We present a 44-year-old man with a history of intractable partial complex seizures secondary to right-sided mesial temporal sclerosis and discuss the magnetic resonance imaging findings utilizing a high resolution technique.

Lesions in the foramen magnum and upper cervical spinal cord often cause an unusual array of sensory changes and atrophic weakness, primarily involving the ipsilateral forelimb. Furthermore, small midline myelotomies performed at C1 often lead to widespread analgesia covering most of the body in patients with chronic pain. These observations challenge physicians' understanding of anatomy and physiology in the upper cervical region. Using single cell recording techniques the authors have shown that spinothalamic neurons in the second cervical segment of cats have complex response properties, often responding to stimuli throughout the body. These findings together with a review of clinical and basic science literature are used to provide explanations for the unusual signs and symptoms observed in patients with upper cervical and foramen magnum lesions.

The number, location, and morphology of thalamically projecting lateral cervical nucleus (LCN) cells were determined in monkey using retrograde transport of wheatgerm agglutinin-conjugated horseradish peroxidase. These data were compared to the total population of LCN neurons as determined by Nissl stain. In 4 Macaca fascicularis and one Saimiri sciureus the average size of the thalamic projection from LCN was found to be 506 +/- 94 cells contralateral to the injections. Thalamically projecting LCN neurons were located between the lower medulla and the third cervical segment; approximately 90% of these cells were in the first two cervical segments. Morphologic analysis of thalamically projecting LCN cells showed that they were smaller in size, and more oblong in shape in caudal regions of the nucleus. In 3 macaques, the average total number of LCN cells was determined to be 1617 +/- 908 on one side, in Nissl material. In these Nissl-stained preparations LCN neurons were found as far caudal as the fourth cervical segment; 68% were located in the first two cervical segments. Hence, thalamically projecting LCN neurons in the monkey are located in the rostral portion of the nucleus and comprise about one-third of the total population. Comparison of these data with reports in the literature imply that, unlike the cat, the major projection from LCN in monkeys is to the mesencephalon rather than to the thalamus.

To date, there are no reports of growth of significant numbers of axons into or across a lesion of the mammalian spinal cord. However, recent studies showing that CNS axons will grow into PNS environments indicate that comparable growth into spinal cord lesions could be achieved if ischemic necrosis could be prevented and the lesion site repopulated by astrocytes and ependymal cells rather than by the macrophages, lymphocytes, and fibroblasts that generally accumulate at sites of CNS injury. To examine this possibility, we made a laminectomy at T5 in rats and crushed the spinal cord for 2 s with a smooth forceps (leaving the dura mater intact to prevent ingrowth of connective tissue). At 1 week, the lesion was filled with mononuclear cells, degenerating nerve fibers, and capillaries that were oriented parallel to the long axis of the spinal cord. By 2 weeks, longitudinally oriented cords of ependymal cells and astrocytes had migrated into the lesion from the adjacent spinal cord, and similarly oriented nerve fibers had begun to grow into the lesion along these capillaries and cellular cordons. The mononuclear cells had now assumed phagocytic activity and were engorged with myelin and other cellular debris. After 3 weeks, the astrocytes had elaborated thick cell processes. The nerve fibers in the lesion were still oriented longitudinally but had increased in number and were often arranged in small fascicles. These observations provide the first histological evidence of growth of nerve fibers into a lesion of the rat spinal cord. We conclude that the intrinsic regenerative capacity of the spinal cord can be expressed if ischemic necrosis and collagenous scarring are prevented and the spinal cord parenchyma is first reconstructed by its nonneuronal constituents.

3-MeV proton beam irradiation studies have been carried out on a commercial aromatic polysulfone (Udell 1700). Physical and mechanical property changes have been monitored as a function of dose. Chemical and spectroscopic analyses have also been performed on the irradiated samples. Results have been compared to those from previous studies with electrons and γ-radiation. A mechanism of proton-induced degradation is proposed.

Un clavier a action de piano pour un instrument de musique electronique ou similaire balaie un actionneur de commutateur (39) par l'intermediaire de contacts de commutation (78, 88) d'une plaque a circuit imprime (60) pour produire des signaux indicatifs de la position et du mouvement d'une touche lorsqu'elle est actionnee. A piano keyboard action for an electronic instrument or similar music sweeps a switch actuator (39) through the intermediary of switching contacts (78, 88) of a printing plate system (60) for producing signals indicative of the position and movement of a button when it is actuated. Le clavier procure une reelle sensation de toucher de piano au moyen d'une rangee de touches enfoncables (12) et de bras (24) associes. The keyboard provides a real sensation of touching piano by a row of depressible keys (12) and arm (24) associates. Chaque bras supporte un actionneur de commutateur (26) ou similaire, avec une force de transmission variant aux differents stades de l'enfoncement de la touche correspondante, la combinaison d'assemblage electrique-mecanique permettant une reponse a1a fois pour ce qui est des resultats et de la reaction cinesthesique simulant une action manuelle du piano. Each arm supports a switch actuator (26) or similar, with a force of transmission varies at different stages of pressing the corresponding button, the electrical-mechanical assembly combination for a response a1a both in terms of results and kinesthetic reaction simulating manual action of the piano.