The history and evolution of transsphenoidal surgery

Initial attempts at transcranial approaches to the pituitary gland in the late 1800s and early 1900s resulted in a mortality rate that was generally considered prohibitive. Schloffer suggested the use of a transsphenoidal route as a safer, alternative approach to the sella turcica. He reported the first successful removal of a pituitary tumor via the transsphenoidal approach in 1906. His procedure underwent a number of modifications by interested surgeons, the culmination of which was A. E. Halstead's description in 1910 of a sublabial gingival incision for the initial stage of exposure. From 1910 to 1925, Cushing, combining a number of suggestions made by previous authors, refined the transsphenoidal approach and used it to operate on 231 pituitary tumors, with a mortality rate of 5.6%. As he developed increasing expertise with transcranial surgery, however, Cushing reduced his mortality rate to 4.5%. With the transcranial approach, he was able to verify suprasellar tumors and achieve better decompression of the optic apparatus, resulting in better recovery of vision and a lower recurrence rate. As a result he and most other neurosurgeons at the time abandoned the transnasal in favor of the transcranial approaches. Norman Dott, a visiting scholar who studied with Cushing in 1923, returned to Edinburgh, Scotland, and continued to use the transsphenoidal procedure while others pursued transcranial approaches. Dott introduced the procedure to Gerard Guiot, who published excellent results with the transsphenoidal approach and revived the interest of many physicians throughout Europe in the early 1960s. Jules Hardy, who used intraoperative fluoroscopy while learning the transsphenoidal approach from Guiot, then introduced the operating microscope to further refine the procedure; he thereby significantly improved its efficacy and decreased surgical morbidity. With the development of antibiotic drugs and modern microinstrumentation, the transsphenoidal approach became the preferred route for the removal of lesions that were confined to the sella turcica. The evolution of the transsphenoidal approaches and their current applications and modifications are discussed.

Approaches to the sellar and parasellar region: anatomic comparison of endonasal-transsphenoidal, sublabial-transsphenoidal, and transethmoidal approaches

Various surgical approaches have been described for treating lesions which arise in the sellar region. The popular transnasal-transsphenoidal and transethmoidal-transsphenoidal approaches avoid the morbidity associated with transcranial operations while allowing enough exposure to successfully remove most lesions that arise in and around the sella. The goal of the present study was to accurately quantify the amount of exposure to the sellar and suprasellar region that the transethmoidal-transsphenoidal, endonasal-transphenoidal, and sublabial-transsphenoidal approaches provide. Each of the three approaches was performed on 14 formalin fixed heads with the aid of the operative microscope. The distances of relevant surgical landmarks, and the amount of exposure superior and anterior to the dorsum sella as well as the lateral exposure obtained through each of these approaches was carefully recorded. The mean distances were then used to calculate the volume of exposure offered by each approach. It was found that the sublabial-transsphenoidal approach afforded the greatest volume of exposure superior and anterior to the dorsum sella. The endonasal-transsphenoidal and the transethmoidal approaches were both found to offer less suprasellar volume exposure, with the transethmoidal approach offering the least. The authors believe the information obtained through this study illustrates some important anatomical relationships which can be used to advantage by the surgeon to tailor the most appropriate approach, depending upon the precise location of the lesion either within the sella or suprasellar region.

Neurosurgery: a historical prologue to the future. 2000 Presidential address

The author provides a brief history of the genesis of organized neurosurgery and, in particular, the formation and evolution of the American Association of Neurological Surgeons. The legacy of neurosurgery is noted and the author discusses the present and future practice of neurosurgery.

Tissue plasminogen activator (tPA) deficiency exacerbates cerebrovascular fibrin deposition and brain injury in a murine stroke model: studies in tPA-deficient mice and wild-type mice on a matched genetic background

Although the serine protease, tissue plasminogen activator (tPA), is approved by the US Food and Drug Administration for therapy to combat focal cerebral infarction, the basic concept of thrombolytic tPA therapy for stroke was challenged by recent studies that used genetically manipulated tPA-deficient (tPA-/-) mice, which suggested that tPA mediates ischemic neuronal damage. However, those studies were potentially flawed because the genotypes of tPA-/- and wild-type control mice were not entirely clear, and ischemic neuronal injury was evaluated in isolation of tPA effects on brain thrombosis. Using mice with appropriate genetic backgrounds and a middle cerebral artery occlusion stroke model with nonsiliconized thread, which does lead to microvascular thrombus formation, in the present study we determined the risk for cerebrovascular thrombosis and neuronal injury in tPA-/- and genetically matched tPA+/+ mice subjected to transient focal ischemia. Cerebrovascular fibrin deposition and the infarction volume were increased by 8.2- and 6. 7-fold in tPA-/- versus tPA+/+ mice, respectively, and these variables were correlated with reduced cerebral blood flow up to 58% (P<0.05) and impaired motor neurological score by 70% (P<0.05). Our findings indicate that tPA deficiency exacerbates ischemia-induced cerebrovascular thrombosis and that endogenous tPA protects the brain from an ischemic insult, presumably through its thrombolytic action. In addition, our study emphasizes the importance of appropriate genetic controls in murine stroke research.

Retroviral vector-mediated transfer and expression of human tissue plasminogen activator cDNA in bovine brain endothelial cells

OBJECTIVES

Gene transfer of thrombolytic enzymes to vascular endothelial cells may influence the kinetics of intravascular thrombosis. This study defines the potential for gene transfer of tissue plasminogen activator (tPA) into bovine brain endothelial cells (BBEC).

METHODS

The retroviral vectors derived from murine leukemia virus (MuLV) were used to transfer human tPA cDNA to BBEC. The tPA activity, tPA antigen and tPA inhibitor 1 (PAI-1) antigen were determined in the supernatant of transduced (BBEC/tPA) cell cultures by an immunoassay.

RESULTS

The tPA antigen and enzymatic activity in cell culture supernatants of BBEC/tPA transduced cells were 75 ng/ml and 14 IU/ml after 4 days, that was 25 and 28-fold higher compared to the respective values in control cells. The PAI-1 antigen was not affected by tPA cDNA transfer. The Western blot assay of cell lysates confirmed that the majority of tPA in BBEC/tPA transduced cells was in the form of free tPA. While the maximal transduction efficiency of BBEC with an amphotropic MuLV vector was about 15%, a MuLV pseudotyped with vesicular stomatitis virus G glycoprotein envelope achieved high > 90% maximal transduction efficiency.

CONCLUSIONS

The fibrinolytic activity of brain endothelial cells can be enhanced by transferring human tPA cDNA. These findings provide an initial step in implementation of future studies that investigate the use of this technology as an adjunctive treatment for cerebrovascular disease.

Invasive pituitary adenomas: significance of proliferation parameters

Although most pituitary adenomas behave in a purely benign fashion, microscopic invasion of the subjacent dura is very common, and clinically overt infiltration of the surrounding dura and bone is apparent at intraoperative inspection in about one third of cases. The factors governing invasive behavior remain unknown but are believed to be separate from those regulating cell proliferation. Histological features alone do not distinguish between benign, invasive, and malignant tumors of adenohypophyseal origin. Multiple attempts have been made to identify prognostic markers of aggressive behavior among these tumors. They include cytogenetic analysis of putative tumor suppressor genes or proto-oncogenes as well as immunohistochemical detection of cell-cycle specific antigens. At present, however, these analyses can neither distinguish the indolent pituitary adenoma from one that will pursue an invasive course, nor reliably predict the prognosis in individual patients.

A functioning composite 'corticotroph' pituitary adenoma with interspersed adrenocortical cells

We report the third case of a composite corticotroph pituitary adenoma with interspersed adrenocortical cells. The 16-year-old male patient presented with findings of delayed growth and pubertal arrest. In contrast to the previous two cases, this patient's tumor showed evidence of function as demonstrated by an elevated urinary cortisol level. Imaging studies revealed a sellar mass that was excised transsphenoidally. Histologic examination revealed a composite tumor composed of distinct populations of large and small cells. The small cell population was PAS-positive and immunohistochemically positive for adrenocorticotrophic hormone. The large cell population had abundant vacuolated cytoplasm, was negative for PAS and adrenocorticotrophic hormone, and stained positively for a panel of markers found in steroid-producing adrenocortical cells. Both populations showed evidence of proliferation as manifest by the presence of MIB-1 positive cells. Ultrastructural examination confirmed the presence of distinct populations of large adrenocortical cells and small corticotrophs, with intercellular junctions between the 2 cell types. The intimate relationship between the 2 cell populations and the activated appearance of the adrenocortical cells suggests the possibility of a paracrine relationship between the two cell types. The identification of 3 patients with sellar tumors demonstrating strikingly similar morphological and ultrastructural features, and all occurring in the second decade of life, suggests that this represents a distinct pathologic entity.

Excessively high prolactin level in a patient with a nonprolactin-secreting adenoma. Case report

The authors report the case of a 48-year-old woman who presented with a nonprolactin-secreting adenoma and a preoperative prolactin level of 662 ng/ml. The patient's neoplasm subsequently enlarged despite normalization of her prolactin level with dopamine agonist therapy. Hyperprolactinemia, with levels of prolactin as high as 150 ng/ml, is commonly associated with sellar tumors and is attributed to disruption of the normal delivery of dopamine to the adenohypophysis. The prolactin level found in this patient represents the highest level attributed to the stalk-section effect reported in the literature and underscores the need for repeated radiographic assessment of patients who are undergoing treatment with bromocriptine and have prolactin levels in the 25 to 1000 ng/ml range.

Intravenous RMP-7 increases delivery of ganciclovir into rat brain tumors and enhances the effects of herpes simplex virus thymidine kinase gene therapy

Herpes simplex virus thymidine kinase (HSV-tk) gene therapy for brain tumors depends on ganciclovir (GCV) and its transport across the blood-brain tumor barrier (BBTB). We examined whether RMP-7, the bradykinin analog and potent BBTB permeabilizer, could enhance the efficacy of GCV treatment of brain tumors by increasing the BBTB delivery of GCV. In vitro, a significant bystander cytocidal effect of GCV was shown in mixed HSV-tk-transduced (HSV-tk+) and control vector-transduced (HSV-tk-) C6 glioma cultures. A dose-dependent cytotoxic effect of GCV on untransformed C6 cells was also shown. In vivo, rats with 100% HSV-tk+ or 100% HSV-tk- intracerebral C6 gliomas were treated for 7 days with intravenous infusions of GCV alone or with GCV and RMP-7 (2.5 microg/kg/day). The growth of HSV-tk+ and HSV-tk- gliomas decreased with increasing doses of GCV. A high dosage (100 mg of GCV/kg/day) eradicated all HSV-tk- and HSV-tk+ tumors. An intermediate dosage (5 mg of GCV/kg/day) reduced the growth of HSV-tk- gliomas by 42% if given alone, and by 88% in combination with RMP-7. A low dosage (0.5 mg of GCV/kg/day) in combination with RMP-7 enhanced the regression of HSV-tk+ gliomas by 87% compared with GCV alone. Low-dose GCV was ineffective in HSV-tk- tumors. RMP-7 increased [3H] GCV tumoral uptake by 2.6- and 1.7-fold in the tumor center and periphery, respectively. We conclude that RMP-7 could be an important adjunctive treatment for suicide gene therapy of brain tumors, while an RMP-7/GCV combination may also have a significant antitumor effect in untransfected gliomas.

Loss of Rb expression in an ACTH-secreting pituitary carcinoma

Little is known about the molecular mechanisms of tumor progression in the pituitary. However, animal studies suggest that the Rb gene may be involved in the development of pituitary carcinoma. Pathologic examination of a pituitary tumor that included both benign and malignant components provided insight into this mechanism. Both benign and malignant tumors were immunoreactive for ACTH. The benign adenoma showed strong nuclear immunoreactivity for Rb, however, both the adjacent sellar carcinoma and its metastases were Rb-negative. This study suggests that loss of Rb may in some cases be important in the progression of pituitary adenoma to carcinoma.

Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature

OBJECT

The authors aimed to develop management strategies for the treatment of herniated thoracic discs and to define indications for selection of surgical approaches. Symptomatic thoracic discs requiring surgery are rare. Between 1971 and 1995, 71 patients with 82 herniated thoracic discs were surgically treated by the authors. The treated group included 34 men and 37 women whose ages ranged from 19 to 75 years, with a mean age of 48 years. The most common sites of disc herniation requiring surgery were from T-8 to T-11. Evidence of antecedent trauma was present in 37% of the patients. Preoperative symptoms included pain (localized, axial, or radicular) in 54 (76%) of the 71 patients, evidence of myelopathy, that is, motor impairment in 43 (61%), hyperreflexia and spasticity in 41 (58%), sensory impairment in 43 (61%), and bladder dysfunction in 17 (24%).

METHODS

Radiological diagnosis for the patients in this series was accomplished by means of myelography, computerized tomography myelography, or magnetic resonance imaging. Classification of the disc location into two groups reveals that 94% were centrolateral and 6% were lateral. Evidence of calcification was present in 65% of patients, and in 7% intradural extension was noted at surgery. Ten patients (14%) were found to have multiple herniations. Four surgical approaches were used for the removal of these 82 disc herniations: transthoracic in 49 (60%), transfacet pedicle-sparing in 23 (28%), lateral extracavitary in eight (10%), and transpedicular in two (2%). Postoperative evaluation revealed improvement or resolution of pain in 47 (87%) of 54, hyperreflexia and spasticity in 39 (95%) of 41, sensory changes in 36 (84%) of 43, bowel/bladder dysfunction in 13 (76%) of 17, and motor impairment in 25 (58%) of 43. Complications occurred in a total of 12 (14.6%) of 82 discs treated surgically. Major complications were seen in three patients and included perioperative death from cardiopulmonary compromise, instability requiring further surgery, and an increase in the severity of a preoperative paraparesis.

CONCLUSIONS

Review of this series, with the attendant complications, together with evaluation of several contemporary thoracic disc series, has facilitated the authors' decision-making process when considering the comprehensive management of these patients, including the selection of a surgical approach.

Cerebrovascular accumulation and increased blood-brain barrier permeability to circulating Alzheimer's amyloid beta peptide in aged squirrel monkey with cerebral amyloid angiopathy

Senescent squirrel monkey is a valuable model to study pathogenesis of cerebrovascular amyloid angiopathy (CAA). Cerebrovascular sequestration and blood-brain barrier (BBB) permeability to 121I-amyloid beta(1-40) synthetic peptide (sA beta(1-40)) were studied in adult versus aged squirrel monkey 1 h after a single intravenous injection. In aged monkey, the half-time of elimination of sA beta(1-40), t(1/2)e, was prolonged by 0.6 h, the systemic clearance, ClSS, was reduced from 1.8 to 1.1 ml/min/kg, and the mean residence time of intact peptide in the circulation was increased by 1 h (45%). In adult monkey, cerebrovascular sequestration of intact sA beta(1-40) was significant, and the BBB permeability was 18.6-fold higher than for inulin. In aged monkey, the sequestration of intact sA beta(1-40) by cortical and leptomeningeal microvessels and the BBB permeability were increased by 5.9, 1.8-, and 2.1-fold, respectively, in the presence of an unchanged barrier to inulin. In brain parenchyma of aged animals, 76.1% of circulating sA beta(1-40) remained intact versus 45.7% in adult. We conclude that multiple age-related systemic effects, i.e., reduced body elimination and systemic clearance of sA beta(1-40), and reduced peripheral metabolism, may act in concert with BBB mechanisms, i.e., increased transendothelial transport and microvascular accumulation of blood-borne sA beta(1-40), and reduced brain metabolism to enhance the development of CAA.

Prolactinomas express human heparin-binding secretory transforming gene (hst) protein product: marker of tumour invasiveness

BACKGROUND AND OBJECTIVE

We have shown previously that heparin-binding secretory transforming gene (hst) overexpression in rat pituitary cells mediates lactotroph tumour growth and stimulates PRL transcription, and that transforming sequences of the gene, which encode fibroblast growth factor-4 (FGF-4), are expressed in human prolactinomas. To further determine the role of hst in human PRL-secreting adenoma pathogenesis we studied the presence of hst protein in these tumours and other types of human pituitary adenoma.

PATIENTS AND DESIGN

Pituitary adenoma tissue samples were obtained at surgery from 14 patients with PRL-secreting adenomas, 5 patients with GH-secreting tumours, 3 with ACTH-secreting, and 13 patients with nonfunctioning tumours. Two normal pituitary tissue specimens were also studied. Clinical data, including tumour invasiveness assessed by preoperative MRI studies, were available. For hst protein immunolocalization, tumour frozen sections were immunostained with antihuman FGF-4 antibody. Immunoperoxidase staining for the proliferation-related nuclear antigen Ki-67 was performed using MIB-1 monoclonal antibody.

RESULTS

Normal anterior pituitary cells did not contain immunoreactive hst protein. Lactotrophs in five of 14 prolactinomas (36%) stained strongly for hst compared with immunoreactive pituicytes in only one of 21 nonfunctioning, GH-, and ACTH-secreting adenomas (P = 0.05). Immunoreactive hst in adenoma cells was detected in 3 of 5 invasive prolactinomas, and in 2 of 9 noninvasive PRL-cell adenomas. Immunostaining for the proliferation-related antigen Ki-67 showed a higher proliferation index in hst-positive adenomas (3.94 + 0.85%) as compared with those immunonegative for hst (1.98 + 0.7%; P = 0.05).

CONCLUSIONS

hst protein may be directly involved in prolactinoma development or progression, particularly in invasive tumours, probably due to the growth promoting effects of FGF-4.

Somatostatin receptor (SSTR) subtype-selective analogues differentially suppress in vitro growth hormone and prolactin in human pituitary adenomas. Novel potential therapy for functional pituitary tumors

Previously, we have shown somatostatin receptor (SSTR) subtype-specific regulation of growth hormone (GH), thyroid-stimulating hormone, and prolactin (PRL) secretion in human fetal pituitary cultures, where GH and thyroid-stimulating hormone are mediated by both SSTR2 and SSTR5, whereas SSTR2 preferentially mediates PRL secretion. We now tested SSTR subtype-selective analogues in primary human GH- and PRL-secreting pituitary adenoma cultures. Analogue affinities determined by membrane radioligand binding in cells stably expressing human SSTR forms were either SSTR2 or SSTR5-selective. Analogues preferential either for SSTR2, including octreotide, lanreotide, and novel compounds with improved affinity for SSTR2, or new SSTR5-selective compounds suppressed GH in tumor cell cultures (up to 44% of control; P < 0.0005). However, novel analogues from both groups were 30-40% more potent than octreotide and lanreotide in suppressing GH (P < 0.05). Heterologous analogue combinations containing both SSTR2- and SSTR5-selective compounds were more potent in decreasing GH than analogues used alone (P < 0.05), or than combinations of compounds specific for the same receptor subtype (P < 0.005). In contrast, SSTR2-selective analogues did not suppress PRL release from six cultured prolactinomas studied. However, new SSTR5-selective analogues suppressed in vitro PRL secretion (30-40%; P < 0.05) in four of six prolactinomas. These results suggest that both SSTR2 and SSTR5 are involved in GH regulation in somatotroph adenoma cells, whereas SSTR5 exclusively regulates PRL secretion from prolactinoma cells. Thus, somatostatin analogues with improved selective binding affinity for these receptor subtypes may be effective in the treatment of either GH- or PRL-secreting adenomas.

Attenuation of brain injury and reduction of neuron-specific enolase by nicardipine in systemic circulation following focal ischemia and reperfusion in a rat model

A reversible middle cerebral artery occlusion was performed in rats to determine whether nicardipine, a dihydropyridine voltage-sensitive Ca++ channel (VSCC) antagonist, exerts neuroprotective effects when administered 10 minutes following an ischemic insult, and if it does, whether this is due to its vasodilatory action and effect on cerebral blood flow (CBF) or to direct blockade of Ca++ entry into ischemic brain cells. An increase in the intracellular calcium, [Ca++]i, plays a major role in neuronal injury during cerebral ischemia. Although a large amount of Ca++ enters neurons through the VSCC during ischemia, inconsistent neuroprotective effects have been reported with the antagonists of the VSCC. An intraperitoneal injection of nicardipine (1.2 mg/kg) was administered to rats 10 minutes after the onset of ischemia, and 8, 16, and 24 hours after occlusion. Cortical CBF was determined by laser-Doppler flowmetry. Neurological and neuropathological examinations were performed after 72 hours. Neuron-specific enolase, a specific marker for the incidence of neuronal injury, was measured in plasma. The CBF and other physiological parameters were not affected by nicardipine during occlusion or reperfusion. However, nicardipine treatment significantly improved motor neurological outcome by 29%, and the infarction and edema volume in the pallium as well as the edema volume in the striatum were significantly reduced by 27%, 37%, and 52%, respectively. Nicardipine also reduced the neuron-specific enolase plasma levels by 50%, 42%, and 59% at 24, 48, and 72 hours after the occlusion, respectively. It is concluded that nicardipine may attenuate focal ischemic brain injury by exerting direct neuroprotective and antiedematous effects that do not depend on CBF.

Transmaxillary approach to the anterior cavernous sinus: a microanatomic study

OBJECTIVE

Several approaches to expose the anterior cavernous sinus have been used, such as frontotemporal, orbitofrontal, anterior subtemporal, and various transfacial approaches. In an effort to gain exposure to the anterior cavernous sinus without necessitating a craniotomy or wide transfacial exposure, the authors in the present study have developed a transmaxillary approach to the cavernous sinus.

METHODS

The approach was developed using data obtained by performing 24 cadaveric dissections. Using a sublabial incision to expose the maxilla, maxillotomy is performed and the course of the infraorbital nerve is identified as a guide to the maxillary branch of the trigeminal nerve. After an osteotomy of the posterior sinus wall and pterygoid plate, the foramen rotundum is identified, which lies a mean of 10 mm from the posterior wall of the maxilla. A superomedial enlargement of the foramen rotundum is then undertaken to ultimately expose the anterior cavernous sinus.

RESULTS

This technique offers access to all cavernous cranial nerves, as well as the entire course of the anterior loop of the internal carotid artery to the origin of the ophthalmic artery. With a mean operative range of 38 mm from the posterior wall of the maxilla to the anterior loop of the internal carotid artery, this approach offers adequate exposure with a short operative distance.

CONCLUSION

The approach may be useful in limited exposure of tumors of the anterior cavernous sinus and some intracavernous vascular lesions.

Prognostic variables in surgery for skull base meningiomas

The authors have retrospectively analyzed selected surgical and pathological observations made among a group of 20 patients harboring recurrent cranial base meningiomas in an attempt to reveal which factors may be important in predicting tumor recurrence. This cohort was compared with a group of 34 patients with cranial base meningiomas that underwent primary resection and in whom tumor recurrence has not been demonstrated over a median follow-up period of 33 months. Features analyzed included brain, cranial nerve, carotid artery, or muscle invasion as well as tumor cellularity, nucleolar prominence, cellular pleomorphism, and percentage of cells staining positive for the Ki-67 antigen. As expected, increased cellularity and tumor necrosis were relatively more prevalent in recurrent tumors. With regard to tumor type, atypical and anaplastic tumors were more common in the group of patients with recurrent tumor compared with the primary group (p < 0.02). As expected, increased cellularity was relatively more prominent in recurrent tumors. Invasion of muscle and bone (72%) was more frequently associated with recurrent tumors, suggesting that these characteristics may be important features of recurrent skull base meningiomas.

Characterization of spherical amyloid protein from a prolactin-producing pituitary adenoma

Prolactin (PRL)-producing pituitary adenomas are in some cases associated with deposition of abundant spherical amyloid; however, the origin of the amyloid has not been established. In this report, a PRL-producing pituitary adenoma composed almost entirely of spherical amyloid was analyzed biochemically. The tumor was removed surgically from a 56-year-old man. Immunohistochemical analysis revealed that residual tumor cells were strongly positive for PRL, while the spherical amyloid was not. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a band of approximately 4 kDa associated with the amyloid, which was not present in a nonamyloid producing prolactinoma. The 4-kDa band is similar in size to other known amyloidogenic peptides. Immunoblot analysis of the tumor material using polyclonal anti-human PRL antibodies revealed a small amount of normal-sized PRL; however, the abundant 4-kDa band was nonimmunoreactive. Amino acid sequencing showed that this peptide represents the first 34 amino acids of the intact PRL protein with a predicted size of 4313 Da. The presence of a small amount of normal-sized PRL in this tumor, as well as elevated circulating levels of PRL implies that intact PRL is being abnormally processed in the formation of spherical amyloid.

Septic cavernous sinus thrombosis following transsphenoidal craniotomy. Case report

The authors present a case of late-onset cavernous sinus thrombosis in a 74-year-old man who had undergone transsphenoidal craniotomy for a pituitary macroadenoma 9 weeks previously. The patient developed headache, rapidly progressive ophthalmoplegia, and signs of orbital congestion. After 2 days of ineffective broad spectrum antibiotic therapy he underwent a second transsphenoidal craniotomy for abscess drainage. Intraoperative cultures grew 4+ non-hemolytic Streptococcus, 4+ Staphylococcus coagulase negative, and 4+ Haemophilus influenzae. The patient was maintained on intravenous antibiotic therapy for the following 6 weeks, resulting in a complete clinical recovery. To the authors' knowledge, this is the first report of a septic cavernous sinus thrombosis following a transsphenoidal craniotomy.

Inhibition of cellular growth and induction of apoptosis in pituitary adenoma cell lines by the protein kinase C inhibitor hypericin: potential therapeutic application

Protein kinase C (PKC) is an enzyme involved in the regulation of cellular growth, proliferation, and differentiation in a number of tissues including the anterior pituitary, in which it is also believed to play a role in hormone secretion. Protein kinase C activity and expression have been found to be greater in adenomatous pituitary cells than in normal human and rat pituitary cells and higher in invasive pituitary tumor cells than in noninvasive ones. Inhibition of PKC activity has been shown in a variety of tumor cells to inhibit growth in a dose-related fashion. The purpose of the current study was to determine whether hypericin, a potent inhibitor of PKC activity that may be administered clinically, alters the growth and proliferation in established pituitary adenoma lines and to determine if inhibition of PKC activity induces apoptosis, as reported in some other tumor cell types. Two established pituitary adenoma cell lines, AtT-20 and GH4C1, were treated with hypericin in tissue culture for defined periods following passage. Inhibition of growth was found to be dose dependent in all three cell lines in low micromolar concentrations of hypericin, as determined by viable cell counts, methylthiotetrazole assay, and [3H]thymidine uptake studies. Concentrations of hypericin as low as 100 nM also induced apoptosis in these established lines, whereas treatment of normal human fibroblasts with a concentration of 10 microM failed to induce apoptosis. The potential use of hypericin in the therapy of pituitary adenomas warrants additional in vitro investigations with the aim of later moving toward therapeutic trials in selected patients in whom surgical or medical therapy has failed.

Enhancement of radiosensitivity in human malignant glioma cells by hypericin in vitro

Hypericin, an antidepressant and antiviral agent being evaluated in phase I and II trials for patients with HIV infection, is known to be a potent protein kinase C inhibitor. We have investigated its effects on cellular response to radiation via a tetrazolium-formazan cell growth rate assay using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and clonogenic assay in three human glioblastoma cell lines, U87-MG, A-172, and T98G, and a low-passage malignant glioma culture, 93-492. At a concentration of 5 microM, hypericin inhibited these cells slightly but caused significant radiosensitization (e.g., the cell survival rate after the radiation treatment was 50.2 and 26.0% in cells treated with 6 Gy and 6 Gy plus 5 microM hypericin in U87-MG cells, respectively; P = 0.0285). Hypericin also enhanced the radiosensitivity significantly in the low-passage glioma 93-492 cells. These findings suggest that hypericin represents a potential new agent in combination with radiation therapy of malignant gliomas.

Treatment of recurrent malignant gliomas with chronic oral high-dose tamoxifen

The present clinical trial was undertaken to assess the clinical safety and possible efficacy of administering tamoxifen to patients with recurrent malignant glial tumors at dosages calculated to achieve levels sufficient to inhibit protein kinase C within the tumor cells. Chronic p.o. tamoxifen was administered in very high dosages to 32 patients (20 males and 12 females; age range, 26-75 years; mean, 49 years) with histologically verified malignant glioma [anaplastic astrocytoma (12 patients) or glioblastoma multiforme (20 patients)] who had demonstrated clinical and radiographical progression or recurrence following external beam radiation therapy (and additional chemotherapy in 11; immunotherapy in 2). The dosage of tamoxifen administered was 200 mg/day to males and 160 mg/day to females given in a twice daily schedule. Clinical and radiographical (defined as a greater than 50% decrease in volume of the enhancing lesion volume on magnetic resonance imaging and a decrease in metabolic activity on serial positron emission tomographic scans) response was noted in 8 patients (25%; 4/12 with anaplastic astrocytoma and 4/20 glioblastoma multiforme), with an additional 6 patients (19%) exhibiting stabilization of disease with minimal side effects. Median survival from the time of diagnosis for the entire cohort was 24 months (104 weeks), for the anaplastic astrocytoma group 42.5 months (185 weeks), and for the glioblastoma group 17.4 months (75.5 weeks). From the initiation of tamoxifen, median survival for the entire cohort was 10.1 months (44 weeks), for the anaplastic astrocytoma group 16 months (69 weeks), and for the glioblastoma group 7.2 months (31 weeks). The mean length of follow-up of all patients after initiating tamoxifen was 16 months (69 weeks), while the mean length of follow-up of alive patients is 22.6 months (98 weeks) (range up to 51 months). These data suggest that a subgroup of patients with malignant gliomas respond or stabilize with chronic high-dose tamoxifen therapy. This therapy may represent an alternative or adjuvant to existing chemotherapies for these tumors; further clinical trials are warranted.

Transport of dopamine at the blood-brain barrier of the guinea pig: inhibition by psychotropic drugs and nicotine

PURPOSE

Transport of dopamine (DA) across the blood-brain barrier (BBB) was examined in guinea pigs.

METHODS

In situ brain perfusion (1-10 min), capillary depletion, and high pressure liquid chromatography (HPLC) were used.

RESULTS

There was a saturable DA influx into the brain with a KM of 389 +/- 55 nM, and a VMAX of 1.95 +/- 0.25 pmol/min/g of brain. The diffusion constant, KD, was not significantly different from zero. About 0.5% of DA remained tightly bound to cerebral microvessels isolated from the perfused brain. DA influx into the brain was not altered by the monoamine oxidase-B (MAO-B) inhibitor pargyline (50 microM). HPLC analysis of perfused brain confirmed transport of intact DA, and no detectable increases in DA metabolites were observed. At perfusate concentrations of 500 nM, several dopaminergic receptor antagonists inhibited [3H]-DA (21 nM) influx; the percent inhibitions for the mixed D1 and D2 antagonists haloperidol and chlorpromazine, the D1 antagonist SCH-23390, and the D2 antagonist spiperone were 90%, 68%, 77%, and 50%, respectively. Brain perfusion with nicotine (500 nM) inhibited DA uptake by 86%. This nicotine effect was not altered by mecamylamine, but was partially prevented by the nicotinic receptor antagonist hexamethonium.

CONCLUSIONS

(a) A significant cerebrovascular permeability to intact DA is mediated by a MAO-B independent specific transport system at the BBB, (b) this system could be inhibited by D1 and D2 DA receptor antagonists, and (c) DA blood-to-brain transport was inhibited by nicotine.

Cellular uptake and transport of methylprednisolone at the blood-brain barrier

Methylprednisolone (MP) is one of the most widely used neuroprotective drugs in neurosurgery. Our knowledge of its pharmacokinetics in the brain and, in particular, whether it can penetrate the blood-brain barrier (BBB) and act in the brain parenchyma is still limited. In this study, we used a vascular brain perfusion technique in guinea pigs, combined with a capillary depletion method, to determine brain uptake and transport of MP at the BBB. 3H-Labeled MP was delivered to the brain by carotid arterial infusions lasting from 1 to 10 minutes; the effects of plasma protein binding, different concentrations of MP, and the glucocorticoid receptor inhibitor, RU486, were examined. The existence of a transport system was inferred from the observation that the volume of distribution of MP in the brain after perfusion exceeded by 2.6 to 6.3 times the plasma volume of the cerebrovascular space marker, sucrose. The rates of undirectional [3H]MP blood-to-brain transport of 0.5 to 0.7 microliters per minute per gram indicated significant but slow transfer. MP available for BBB transport was not restricted to its free plasma fraction but, instead, included the albumin- and globulin-bound fractions. A portion of steroid remained concentrated (sequestered) by the capillary endothelium, and from there, the label was distributed into brain parenchyma. Both MP binding and transport at the BBB exhibited saturable kinetics. RU486 produced an inhibition of MP BBB transport and binding with an affinity that seemed to be 30 to 60% higher than that of the steroid itself. We concluded that MP first binds to the brain capillaries and then crosses the BBB at a low rate, most likely by using a saturable mechanism that may involve a cytoplasmic endothelial glucocorticoid receptor.

Transport of circulating reduced glutathione at the basolateral side of the anterior lens epithelium: physiologic importance and manipulations

Transport of circulating reduced glutathione (GSH) was studied at the basolateral side of the lens epithelium by using an in situ vascular eye perfusion technique in guinea-pigs with rapid sampling to ensure detecting initial uptakes. The unidirectional transport rates of [35S]-GSH (4 nM) from plasma and aqueous into the epithelial cytosol were 0.046 +/- 0.003 and 6.88 +/- 0.39 min-1, respectively. HPLC analysis indicated that over 94% of [35S]-GSH remained intact in the epithelium and cortex in the presence or absence of gamma-glutamyl transpeptidase inhibitor, serine borate. Simultaneous infusion of [35S-cysteine]-GSH and [3H-glycine]-GSH confirmed the non-involvement of gamma-glutamyl transpeptidase in GSH transport across the lenticular membranes by showing that 35S/3H ratio in the epithelium and cortex was the same as in the aqueous and plasma. GSH epithelial influx was reduced by 53% (P < 0.01) by 0.3 mM sulphobromophtalein-GSH, a GSH conjugate that does not inhibit the facilitative GSH transporter, RcGshT, recently found in the lens. At physiologic concentration of circulating GSH at 30 microM, GSH epithelial influx was 0.77 nmol min-1 g-1; a t1/2 of 85.4 hr was estimated if endogenous epithelial GSH had to be replaced exclusively by plasma-derived GSH. The level of GSH in the epithelium was increased by 38% (P < 0.05) by 1 hr arterial infusion of GSH at 20 mM. The aqueous concentration of GSH under these conditions was 1.2 mM so that accumulation in the epithelium occurred a greater than six-fold concentration gradient. It is concluded that: (a) transport of GSH at the basolateral side of the epithelium is mediated by a concentrative mechanism distinct from RcGshT: (b) circulating GSH may represent a major source for epithelial GSH under physiologic conditions; and (c) the level of GSH in the epithelium can be manipulated by exogenous GSH.

Petroclival meningiomas: surgical experience in 109 cases

The surgical removal of petroclival meningiomas has historically been associated with a high incidence of morbidity and mortality. The 109 consecutive patients included in the present retrospective study represent a combined series of tumors operated on by the four authors during a period from 1980 to 1992. The series is composed of 40 men and 69 women ranging in age from 25 to 75 years (mean 51 years). Surgical approaches to tumors in this series included simple retromastoid (60 cases), combined supra- and infratentorial petrosal (22), transtemporal (primary transsigmoid retrolabyrinthine, translabyrinthine, or transcochlear (12), subtemporal (11), and frontotemporal transcavernous (eight). Gross-total removal was achieved in 75 patients (69%). Recurrence or progression of disease occurred in 14 patients (13%) over a 6.1-year mean follow-up period, and it was found within the cavernous sinus in 12 of these cases. Four recurrent cases demonstrated histological compatibility with malignant meningioma. Perioperative death occurred in four patients, and there were 56 significant complications in 35 other patients. Review of this series, with the attendant complications, has facilitated the authors' decision-making when considering the risk of gross-total removal in selected patients with asymptomatic cavernous sinus invasion or tumor adherent to the brainstem.

Protein kinase C and growth regulation of pituitary adenomas

The present study was undertaken to explore the role of the Protein Kinase C (PKC) signal transduction system in growth regulation of pituitary adenomas. Primary tumor cultures were plated from fresh surgical tumor specimens. The PKC inhibitors Staurosporine and Tamoxifen were added at varying dosages to the cell cultures. Measurements of cell proliferation were performed by [3H]-thymidine uptake and the [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] (MTT) assay. After a 48 h treatment period, both [3H]-thymidine uptake and absorbance on the MTT assay decreased in a dose-related manner in both the staurosporine and tamoxifen-treated cultures (IC50 of 10 nM and 30 microM respectively). Direct measurement of PKC activity using an in vitro assay revealed very high activity (range of 1465-5708 pmol/min/mg protein; within the range previously published for malignant glioma specimens) in 12 frozen specimens of pituitary adenomas (9 nonfunctional adenomas, 1 prolactinoma, 1 gonadotrophin-secreting and 1 corticotroph-secreting adenoma). In contrast, PKC activity measured in normal adenohypophysis was comparatively very low. These data indicate that pituitary adenoma cells display high PKC activity and are sensitive to growth inhibition by PKC inhibitors. These data suggest a role for the PKC system in regulating pituitary tumor growth, which may have implications for future therapy of these tumors.

The transfacet pedicle-sparing approach for thoracic disc removal: cadaveric morphometric analysis and preliminary clinical experience

A number of operative techniques have been described for the treatment of herniated thoracic discs. The transfacet pedicle-sparing approach allows for complete disc removal with limited spinal column disruption and soft-tissue dissection. Fifteen cadaveric spinal columns were used for evaluation of exposure, development of thoracic microdiscectomy instrumentation, and establishment of morphometric measurements. This approach was used to remove eight thoracic discs in six patients. Levels of herniation ranged from T-7 through T-11. Preoperatively, all patients had moderate to severe axial pain, and three (50%) of the six had radicular pain. Myelopathy was present in four (67%) of the six patients. Through a 4-cm opening, the ipsilateral paraspinal muscles were reflected, and a partial facetectomy was performed. The disc was then removed using specially designed microscopic instrumentation. Postoperatively, the radiculopathy resolved in all patients. Axial pain and myelopathy were completely resolved or significantly improved in all patients. The minimal amount of bone resection and muscle dissection involved in the operation allows for: 1) decreased operative time and blood loss; 2) diminished perioperative pain; 3) shorter hospitalization time and faster return to premorbid activity; 4) avoidance of closed chest tube drainage; and 5) preservation of the integrity of the facet-pedicle complex, with potential for improvement in outcome related to axial pain. This technique appears best suited for the removal of all centrolateral discs, although it has been used successfully for treating a disc occupying nearly the entire ventral canal. The initial experience suggests that this approach may be used to safely remove appropriately selected thoracic disc herniations with good results.

Pituitary adenomas. Correlation of the cytologic appearance with biologic behavior

OBJECTIVE

To determine the extent of nuclear pleomorphism in pituitary adenomas and the relationship of these cytologic changes to clinical features, endocrine evaluations and proliferative potential.

STUDY DESIGN

The study group consisted of 93 sequential patients with pituitary adenomas in which smear and touch preparations were performed. Nuclear pleomorphism was assessed semiquantitatively and compared to immunohistochemical analyses of pituitary hormones on formalin-fixed paraffin sections, endocrine evaluations, clinical observations and proliferative potential as determined by immunoreactivity to Ki-67 on frozen sections.

RESULTS

Varying degrees of nuclear pleomorphism were observed in 66/93 tumors. However, these changes were more pronounced in clinically functioning (growth hormone, prolactin or ACTH), as compared to nonfunctioning, tumors (P < .01). Pleomorphism did not correlate with macroscopic invasiveness. The pituitary adenomas that showed pleomorphism had significantly higher Ki-67 indices than did those without nuclear changes (P < .02). Significantly higher Ki-67 expression was also found in clinically functioning tumors when compared to nonfunctioning tumors (P < .03).

CONCLUSION

Significant nuclear pleomorphism is common in functional pituitary adenomas of several types but does not correlate with more aggressive behavior.

Secondary pharyngeal myotomy for tracheoesophageal speech

Pharyngeal myotomy in the post-laryngectomy patient has been described to reduce pharyngoesophageal spasm and facilitate vocal rehabilitation and tracheoesophageal speech. This report describes the complications and speech outcomes in 22 consecutive patients who underwent a secondary pharyngeal myotomy. The patients were all drawn from a hospital clinic dedicated to voice rehabilitation after laryngectomies. Their ages ranged from 54 to 81-years-old with a mean of 64. Two patients suffered surgical complications--both had pharyngocutaneous fistulas which resolved with conservative management. One patient had an incomplete myotomy and was treated with injection of boulinum toxin in the pharyngeal plexus. This treatment resulted in good vocalization. Seventeen of 22 patients in the study were long-term TEP users, and all of these were judged to have good speech quality. Our experience with myotomy for TEP speech demonstrates that many patients with pharyngoesophageal spasm can benefit from the procedure and successfully phonate. There were several complications related to the procedure, but these were successfully managed conservatively and without long-term sequela. Pharyngeal myotomy as an adjunct to TEP is useful and effective in selected patients.

Tonsil lymphoma presenting as tonsillitis after bone marrow transplantation

Bone marrow transplantation for the treatment of leukemia is increasingly successful in rendering patients disease free. However, it has become evident that the associated severe immunosuppression predisposes this population to an increased risk for other neoplastic disorders. We report on six patients in whom non-Hodgkin's lymphoma of the tonsillar region developed within 5 months after T-cell-depleted bone marrow transplantation for the treatment of leukemia at Memorial Sloan-Kettering Cancer Center from October 1990 to October 1992. These patients initially had what appeared to be infectious exudative pharyngitis/tonsillitis; however, they did not improve with medical therapy. Because of the persistence of pharyngitis/tonsillitis in association with cervical lymphadenopathy and odynophagia, the patients underwent definitive biopsy in the form of tonsillectomy, cervical lymph node biopsy, or both. Histopathologic review revealed non-Hodgkin's lymphoma. An association with Epstein-Barr virus has been noted in five of these patients. This article is aimed at alerting the clinician to consider the diagnosis of lymphoma in a patient with persistent pharyngitis/tonsillitis despite adequate medical therapy after bone marrow transplantation.

Tracheoesophageal puncture in irradiated patients

Tracheoesophageal puncture (TEP) with use of a voice prosthesis is widely accepted as an excellent method of postlaryngectomy vocal rehabilitation. Many patients with advanced cancer require postoperative radiotherapy (RT), while other cancer patients have been treated with RT as a primary treatment and come to laryngectomy for salvage. The influence of RT on outcome of the TEP procedure with respect to successful speech and potential complications has not been widely discussed. We retrospectively reviewed 77 consecutive cases of TEP in patients who had received RT and laryngectomy for laryngeal cancer. All cases had a minimum of 6 months of follow-up. All 77 patients were successful in obtaining speech with the TEP, and 75 (97%) continued to be TEP users thereafter. Eight patients (10%) developed complications in the course of treatment. There was no mortality. In selected patients, TEP after RT is a relatively safe and effective method of vocal rehabilitation.

Organ-function preservation in advanced oropharynx cancer: results with induction chemotherapy and radiation

PURPOSE

To evaluate the feasibility and efficacy of a strategy using induction chemotherapy followed by radiation therapy (RT) as a means of organ-function preservation in patients with advanced oropharynx cancer.

PATIENTS AND METHODS

From January 1983 to December 1990, 33 patients with advanced squamous cell oropharynx cancer whose appropriate surgical management would have required a tongue procedure and potential total laryngectomy were treated with one to three cycles of cisplatin (CDDP)-based induction chemotherapy. Patients with a complete response (CR) or partial response (PR) at the primary site then received definitive external-beam RT with or without interstitial implant with or without neck dissection with surgery to the primary tumor site reserved for disease persistence or relapse; patients with less than a PR after chemotherapy had appropriate surgery and postoperative RT recommended.

RESULTS

With a median follow-up period of 6.2 years, actuarial overall and failure-free survival rates at 5 years are 41% and 42%, respectively. Chemotherapy toxicity contributed to the death of two patients and was possibly a factor in two others. Local control was achieved in 14 patients (42%) without any surgery to the larynx or tongue. Among 13 patients currently alive, all had a preserved larynx and only one required tongue surgery; 12 of 13 have speech subjectively described as always understandable; and nine of 13 have no significant restrictions in their diet.

CONCLUSION

This treatment program is feasible and effective in patients with advanced oropharynx cancer and produces an excellent functional outcome in most long-term survivors. Modifications to optimize patient selection, minimize toxicity, and improve local control are indicated. The relative toxicity, efficacy, and functional outcome provided by this and other chemotherapy and RT programs versus either standard surgery and/or RT options can only be addressed in a randomized comparison of these therapies.

Paradoxical elevation of Ki-67 labeling with protein kinase inhibition in malignant gliomas

The monoclonal antibody Ki-67 recognizes a nuclear antigen expressed in the G1, S, G2, and M phase of the cell cycle and has been used extensively as an indicator of cellular proliferation in malignant gliomas, both in the laboratory and clinically. Recently, protein kinase C (PKC) inhibitors have been demonstrated to inhibit malignant glioma growth both in in vitro and in vivo. This study was undertaken to determine whether Ki-67 could function as an indicator of cellular proliferation rate after PKC inhibition in gliomas and to explore cell cycle specificity of such inhibition. Both established and low-passage malignant glioma cell lines have previously been shown to be sensitive to growth inhibition by the PKC inhibitors staurosporine and tamoxifen in vitro (IC50 in the nanomolar and micromolar ranges, respectively), as measured by cell numbers, [3H]thymidine uptake, and flow-cytometric DNA analysis. However, in the same cells that are inhibited by staurosporine and tamoxifen on these assays, and on the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay in the present study, the Ki-67 labeling index paradoxically increased in a dose-related manner with the same treatments, as measured by immunohistochemistry and confirmed by flow cytometry. For example, in established line U-87, a 20.5% decrease in thymidine uptake and a 28.5% decrease in absorbance on the MTT assay produced by tamoxifen at 1 microM was associated with an increase in Ki-67 labeling from 42% to 62%; staurosporine, which produces a 78.8% decrease in thymidine uptake in cell line A-172 at 10 nM, produced an increase in Ki-67 labeling from 19% to 32%. In this regard, Ki-67 labeling of glioblastoma tissue from a patient treated with high-dose tamoxifen yielded results within the range of 10% to 15% (consistent with values seen in untreated glioblastoma), despite tumor regression with treatment. The authors' interpretation of these results is that these PKC inhibitors are halting the cell cycle in the G1 phase or the G1-S transition (beyond G0 but before S-phase), resulting in a paradoxical increase in labeling while arresting growth. Two important implications from these observations are that Ki-67 is not a reliable indicator of cellular proliferation after treatment with PKC inhibitors and that these inhibitors used at the doses given above halt cell growth in a phase-specific manner.

Blood-to-lens transport of reduced glutathione in an in situ perfused guinea-pig eye

Transport mechanisms of reduced glutathione (GSH) in intact eye are poorly understood. In this study, an in situ vascular eye perfusion (VEP) model was used to characterize the transport kinetics of circulating GSH into the aqueous humor and lens in guinea pigs. Radiolabeled [35S]GSH or [3H]GSH and [14C]sucrose (an extracellular space marker) were exposed to the blood-aqueous barrier up to 10 min, and uptake of tracers by the aqueous humor and lens was determined in the presence of different concentrations of unlabeled peptide as GSH, a gamma-glutamyl compound as a derivative of GSH (GSH monoethyl ester), and an inhibitor of gamma-glutamyl transpeptidase (GGT) activity. Plasma-aqueous and aqueous-lens compartmental unidirectional transport constant, K(in), and the initial rapid volume of distribution, Vi, were estimated by multiple-time-point graphic analysis. Our results indicated that both labeled GSH and sucrose entered the aqueous humor slowly at comparable rates with respective blood-aqueous K(in) values of 1.34 +/- 0.12 and 1.25 +/- 0.08 min-1 x 10(3). In contrast to blood-aqueous transport, GSH uptake by the lens was rapid, and the respective aqueous-lens K(in) values for labeled GSH and sucrose were 79.3 +/- 4.1 and 3.5 +/- 0.7 min-1 x 10(3). Over 94% of plasma-derived GSH remained in its original molecular form of GSH in the lens, during the 10 min perfusion both with and without the GGT inhibitor, serine borate. The amount of [35S]GSH in lens anterior epithelium (dpm mg-1) was more than three times that of aqueous humor (dpm microliter-1) within only 10 min of VEP. There was also significant accumulation of [35S]GSH in the interior cortex, as indicated by 10-min cortex/aqueous ratio of 0.65. A specific GGT independent GSH transport system was demonstrated in the lens in situ, with a Km of 26 +/- 3 microM, and Vmax of 34 +/- 3 pmol min-1 g-1 of whole lens tissue water. The lenticular influx of GSH was inhibited by GSH monoethyl ester with an affinity that was half that for GSH. It is concluded that: (a) uptake of plasma-derived GSH into the aqueous humor is by simple diffusion, and (b) cellular uptake of GSH by the lens is carrier-mediated via mechanism that is separate from the transpeptidation metabolic pathway.

Hypericin: a potential antiglioma therapy

Hypericin, a polycyclic aromatic dione isolated from plants, is presently being clinically evaluated as an antiviral agent in the treatment of human immunodeficiency virus (HIV) infection. In addition, it is known to be a potent protein kinase C inhibitor. To evaluate its potential as an inhibitor of glioma growth, an established (U87) and low-passage glioma line (93-492) were treated with hypericin in tissue culture for a period of 48 hours after passage. Hypericin inhibited the glioma growth in a dose-related manner, with a marked inhibition of growth in the low-micromolar concentration range (e.g., in line U87 and low-passage line 93-492, a concentration of hypericin of 10 mumol/L produced 62 and 76% decreases in [3H]thymidine uptake, respectively). Because the reported inhibitory effects of protein kinase C are enhanced by visible light, [3H]thymidine uptake was measured in both the presence and the absence of visible light. In glioma line A172, the presence of light slightly increased the inhibitory effect of hypericin. Moreover, an apoptosis (i.e., programmed cell death) assay was performed to determine whether the treatment of glioma cells with hypericin was cytostatic or cytocidal. Cells were harvested, and purified deoxyribonucleic acid (DNA) was analyzed by agarose gel electrophoresis. DNA from cells treated with hypericin for 48 hours exhibited a classical "ladder" pattern of oligonucleosome-sized fragments characteristic of apoptosis. These data suggest that the proven safe drug hypericin may have potential as an antiglioma agent; we suggest clinical trials.

Cranioplasty with the Medpor porous polyethylene flexblock implant. Technical note

The authors describe the use of a porous polyethylene Flexblock implant for cosmetic cranioplasty. The implant may be used to cover any small- or medium-sized (< 8 cm) cranial defect, offering similar cosmetic results to standard alloplast cranioplasty while decreasing operation time. The porous implant design permits ingrowth of soft tissue and bone to increase implant strength and decrease the risk of infection. The Flexblock alloplast has been utilized in 25 cases with excellent cosmetic results and no implant-related complications.

Larynx preservation with combined chemotherapy and radiation therapy in advanced hypopharynx cancer

Twenty-five untreated patients with advanced, resectable squamous cell carcinoma of the hypopharynx, for whom standard treatment would have required total laryngectomy, were treated with one to three cycles of cisplatin-based chemotherapy with larynx preservation as the goal. Patients with a major (complete or partial) response to chemotherapy at the primary site were treated with definitive radiation therapy, with total laryngectomy reserved for salvage; patients with less than a partial response to chemotherapy had total laryngectomy and postoperative radiation therapy recommended. Four patients had a poor response to chemotherapy and thus were not candidates for laryngectomy. Total laryngectomy was required for initial induction chemotherapy failure in five patients and for local recurrence in five others. Three additional patients had unresectable recurrence. Successful larynx preservation was achieved in 32% (8 of 25). With a median follow-up period of 41 months, the actuarial overall and failure-free 2-year survival rates were 44% and 32%, respectively. These preliminary data suggest larynx preservation is feasible in patients with advanced lesions of the hypopharynx. Improved local and regional control must be incorporated into the larynx preservation approach for hypopharyngeal lesions. A prospective, randomized study is necessary for a more valid comparison with conventional therapy, including comparative assessments of survival, morbidity, cost and functional results.

Use of decision analysis in planning a management strategy for the stage N0 neck

OBJECTIVE

There are three major strategies in the treatment of patients with a stage N0 neck with squamous cell cancer of the head and neck: elective neck dissection, elective neck irradiation, and observation. Each has appropriate salvage strategies in the event of local recurrence. We used decision analysis to determine the optimal strategy for neck treatment as a function of the probability of occult cervical metastasis.

DATA SOURCES

We used the bibliographies of current articles and books to access clinical studies of patients with stage N0 neck cancer.

STUDY SELECTION

Studies that included large numbers of patients and contained a minimum 2-year follow-up, with results analyzed in terms of outcome as a function of stage of neck disease, were included.

DATA EXTRACTION

Specific data points were extracted from the studies independently by multiple observers, and mean values were used in the decision analysis.

DATA SYNTHESIS

A decision tree was constructed with use of a computer model to compare the three management strategies. Probabilities of each of the possible events depicted in the trees were inserted into the tree structure. These probabilities were gleaned from the literature as described above. A sensitivity analysis was performed to determine the optimal threshold for treatment of the neck.

CONCLUSION

A patient with primary squamous cell carcinoma of the head and neck and stage N0 neck status should be observed if the probability of occult cervical metastasis is less than 20%. If the probability is greater than 20%, treatment of the neck is warranted. The treatment plan should ideally involve a single modality of therapy; both neck dissection and radiation therapy are quite efficacious in the clinical context, and the decision of which one to employ should be driven by the treatment of the primary lesion. Decision analysis is useful in complex clinical situations.

Interleukin-6 and interleukin-6 receptor gene expression in pituitary tumors

Interleukin-6 (IL-6) is a multifunctional cytokine which plays a role in the stimulation, inhibition, differentiation, and regulation of cell growth. IL-6 has been shown to act as an autocrine growth factor in several tumors, and is expressed by a variety of tumors. IL-6 also exhibits a regulatory role in the hypothalamo-pituitary axis. It is produced by both the hypothalamus and the pituitary, and it induces the secretion of anterior pituitary hormones. Because of the regulatory role of IL-6 in tumor growth and its involvement in the pituitary, we decided to evaluate IL-6 and IL-6 receptor expression in pituitary tumors. For this purpose we utilized complimentary cDNA probes specific for the IL-6 and IL-6 receptor mRNA, as well as monoclonal anti-IL-6 antibodies for immunohistochemical analysis. Our results show that the IL-6 gene is expressed in the normal pituitary tissue. However, the non-functioning and functioning pituitary tumors such as the prolactin and growth hormone secreting tumors express increased levels of the IL-6 gene. The IL-6 receptor gene was only expressed in the prolactin secreting and non-functioning pituitary tumors. These results show that the IL-6 and IL-6 receptor gene expression is enhanced in pituitary tumors, thus suggesting a possible role of IL-6 in the pathogenesis of these tumors.

Evidence for transcapillary transport of reduced glutathione in vascular perfused guinea-pig brain

Using a vascular brain perfusion model in the guinea-pig, the net uptake of [35S]-GSH by the brain was found to be linear and similar in various regions during 10 min perfusion. Dual labeled [35S and 3H] GSH taken up by the brain had the same isotope ratio as the injected stock whether or not gamma- glutamyl transferase was inhibited. Greater than 96% of brain uptake of [35S]-cysteine-labeled GSH and [3H]-glycine-labeled GSH were in intact form. Transcytosis of [35S]-GSH from lumen into brain parenchyma was demonstrated using a capillary depletion technique. Both GSH and GSH-monoethyl ester inhibited [35S]-GSH transport. Thus, we have demonstrated blood-brain barrier extraction of circulating GSH in a brain perfusion model, and the transcytosis of intact GSH into the brain parenchyma without breakdown.

Protein kinase C inhibitors induce apoptosis in human malignant glioma cell lines

Previous work has demonstrated the importance of the protein kinase C (PKC) system in regulating glioma growth, and has led to clinical trials utilizing PKC inhibitors as adjuncts in the therapy of patients harboring malignant gliomas. This study was performed to explore the possibility that inhibition of PKC in gliomas was triggering an apoptosis signal. Glioma cell lines were treated with PKC inhibitors staurosporine (10 nM), and tamoxifen (10 microM). DNA from cells treated with each of these drugs exhibited a 'ladder' pattern of oligonucleosome-sized fragments characteristic of apoptosis, thus suggesting that in glioma cells, these drugs may be cytocidal in action.

Nicotine downregulates alpha 2 isoform of Na,K-ATPase at the blood-brain barrier and brain in rats

Effects of chronic nicotine treatment on the relative levels of expression of Na,K-ATPase alpha and beta subunit isoforms were determined in rat cerebral microvessels and capillary-depleted brain homogenates by Western blot analysis. Nicotine, 4.5 mg/kg/day, was administered s.c. by osmotic mini-pumps for 14 days. Expression of alpha 2 isoform in microvessels and brains of nicotine-treated rats was reduced to 0.26 and 0.58 of control levels, respectively. Expression of alpha 1, alpha 3, beta 1 or beta 2 was unchanged. Nicotine decreased cerebromicrovascular and brain Na,ATPase enzymatic activities by 22% and 17%, respectively. It is suggested that chronic exposure to nicotine reduces expression of functional Na,K-ATPase at the blood-brain barrier and brain by downregulating the alpha 2 isoform.