Supratentorial-infraoccipital approach for posteromedial temporal lobe lesions

The use of the supratentorial-infraoccipital approach is reported in seven patients with posteromedial temporal lobe lesions. No patient had permanent morbidity. Gross total resection of three low-grade gliomas and two gangliogliomas was achieved in five patients; one patient had subtotal resection of a low-grade glioma with adjacent gliosis, and one was initially thought to have a glioma but proved to have encephalomalacia on final pathological analysis. The patients ranged in age from 5 to 34 years. All seven patients presented with seizures, and four had uncontrolled seizures preoperatively. Six have been seizure-free since surgery (mean follow-up period 15 months), and one is well controlled on anticonvulsant medication. An anatomical study was performed to delineate the microsurgical anatomy relevant to operating on the medial temporal lobe through this posterior approach. A viewing wand intraoperative navigational system was utilized with this approach and proved helpful in gaining access as far anterior as the uncus through this occipital craniotomy. This approach is favorable in selected patients with posterior, medial, temporal lobe tumors because resection of otherwise difficult lesions may be accomplished without sacrificing lateral temporal lobe cortex or transecting the optic radiations.

Effect of vancomycin infusion on cardiac function in patients scheduled for cardiac operation

Patients scheduled for cardiac operation often receive vancomycin before the operation to decrease postoperative staphylococcal wound infections. In animal studies, vancomycin depressed cardiac function approximately 15%. Because of the potentially serious consequences of myocardial depression in patients undergoing cardiac operation, we examined the effect of vancomycin infusion on cardiac hemodynamics in patients scheduled for cardiac operation. Patients who were scheduled for cardiac operation and vancomycin prophylaxis were enrolled in our study. After baseline cardiac output, mean arterial pressure, central venous pressure, and pulmonary capillary wedge pressure were measured, 1 gm of vancomycin HCl was infused over 1 hour. Cardiac output, mean arterial pressure, central venous pressure, and pulmonary capillary wedge pressure were measured at 15, 30, 60, 90, and 120 minutes after the start of the infusion. In the 46 patients that completed the study, no significant change was observed in cardiac output or systemic vascular resistance at any time when compared with baseline. Mean arterial pressure increased significantly (p = 0.03) between baseline (90.8 +/- 2.4 standard error of mean) and 90 minutes (94.1 +/- 2.4 standard error of mean). One patient had a transient 30% fall in mean arterial pressure and systemic vascular resistance with facial flushing during the infusion. In conclusion, we found that vancomycin infusion over 1 hour in patients before cardiac operation is safe and not associated with cardiac depression.

Regulation and mechanisms of gene amplification

Amplification in rodent cells usually involves bridge-breakage-fusion (BBF) cycles initiated either by end-to-end fusion of sister chromatids, or by chromosome breakage. In contrast, in human cells, resistance to the antimetabolite N-(phosphonacetyl)-L-aspartate (PALA) can be mediated by several different mechanisms that lead to overexpression of the target enzyme carbamyl-P synthetase, aspartate transcarbamylase, dihydro-orotase (CAD). Mechanisms involving BBF cycles account for only a minority of CAD amplification events in the human fibrosarcoma cell line HT 1080. Here, formation of a 2p isochromosome and overexpression of CAD by other types of amplification events (and even without amplification) are much more prevalent. Broken DNA is recognized by mammalian cells with intact damage-recognition pathways, as a signal to arrest or to die. Loss of these pathways by, for example, loss of p53 or pRb tumour suppressor function, or by increased expression of ras and myc oncogenes, causes non-permissive rat and human cells to become permissive both for amplification and for other manifestations of DNA damage. In cells that are already permissive, amplification can be stimulated by overexpressing oncogenes such as c-myc or ras, or by damaging DNA in a variety of ways. To supplement genetic analysis of amplification in mammalian cells, an amplification selection has been established in Schizosaccharomyces pombe. Selection with LiCl yields cells with amplified sod2 genes in structures related to those observed in mammalian cells. The effect on amplification in S. pombe can now be tested for any mutation in a gene involved in repair of damaged DNA or in normal cellular responses to DNA damage.

The Lister Hill National Center for Biomedical Communications

On August 3, 1968, the Joint Resolution of the Congress established the program and construction of the Lister Hill National Center for Biomedical Communications. The facility dedicated in 1980 contains the latest in computer and communications technologies. The history, program requirements, construction management, and general planning are discussed including technical issues regarding cabling, systems functions, heating, ventilation, and air conditioning system (HVAC), fire suppression, research and development laboratories, among others.

m-Chlorophenylpiperazine decreases food intake in a test meal

We studied the effect of the 5-HT receptor agonist, m-chlorophenylpiperazine (mCPP) (0.4 mg/kg), on food intake in 12 healthy female volunteers, in a double-blind placebo controlled design. Compared to placebo, mCPP significantly lowered food intake in a test meal. Treatment with mCPP also caused significant increases in ratings of nausea and light-headedness, though these effects had remitted by the time of the test meal. The results suggest that activation of brain 5-HT2C receptors may lower food intake in humans; it is also possible, however, that the hypophagic effect of mCPP in the present study could be a consequence of its adverse subjective side effects.

Giant posterior communicating artery aneurysm presenting as third ventricle mass with obstructive hydrocephalus. Case report

The case of a giant posterior communicating artery (PCoA) aneurysm is reported in which the initial presentation was coma secondary to obstructive hydrocephalus. The primary radiological diagnosis was a probable craniopharyngioma. A cerebral angiogram revealed a partially thrombosed giant PCoA aneurysm on the right side. The patient underwent pterional craniotomy with aneurysm clipping and thrombectomy to relieve mass effect, and has made a good recovery. Review of the literature documents that giant PCoA aneurysms are rare. This is believed to be the first reported case of a PCoA aneurysm presenting as a third ventricle mass with obstructive hydrocephalus. The magnetic resonance imaging characteristics of those third ventricle masses that mandate vascular workup are discussed.

Delayed postoperative tethering of the cervical spinal cord

Tethering of the spinal cord in the lumbar and sacral regions of children with congenital anomalies is a well-recognized problem; however, tethering in the cervical region has rarely been reported. A search of the literature revealed no reports of symptomatic postoperative cervical spinal cord tethering. The authors present five cases of delayed postoperative cervical spinal cord tethering and discuss the benefit of detethering in these patients. All five patients were young (16 to 42 years of age) at presentation. All had done well after an initial surgical procedure but returned between 1 and 31 years postoperatively with symptoms including severe headache, upper-extremity pain, and progressive neurological deficits. In each case, magnetic resonance imaging indicated dorsal tethering of the cord in the cervical region. Surgical exploration with microscopic sharp detethering of the cervical cord was performed on each patient with favorable results. To avoid retethering, wide Tutoplast duraplasty is recommended.

Interleukin 2 receptor gamma chain expression on resting and activated lymphoid cells

The interleukin 2 receptor (IL-2R) is known to be comprised of at least three genetically distinct subunits termed alpha, beta, and gamma. These chains can be expressed individually or in various combinations resulting in distinct receptors with different affinities for IL-2. In contrast to alpha and beta, the cell surface expression of the gamma chain protein previously has not been well-characterized. To examine cell surface expression of IL-2R gamma on hematopoietic cells, we developed two new monoclonal antibodies (mAbs) specific for this protein. Both 1A11 (immunoglobulin [IgG1]) and 3G11 (IgM) specifically reacted with murine cells transfected with IL-2R gamma cDNA, and immunoprecipitation studies indicated that both antibodies precipitated a protein of approximately 62-65 kD. Scatchard analysis of IL-2 binding to murine cells transfected with cDNA-encoding combinations of IL-2R components demonstrated that neither beta nor gamma chain bind IL-2 with measurable affinity, but coexpression of both beta and gamma is sufficient to form an intermediate affinity receptor. In the absence of gamma chain, beta chain interacts with alpha chain to form a "pseudo-high" affinity receptor. In contrast, gamma chain does not appear capable of interacting with alpha in the absence of beta chain. Thus, gamma chain appears to interact only with beta, but beta chain is capable of interacting with both alpha and gamma. Using the newly developed mAbs to examine cell surface expression by immunofluorescence, resting T cells were found to express low levels of gamma chain without detectable alpha or beta. Early after mitogen stimulation, T cells expressed higher levels of alpha, beta, and gamma. However, at later time points, T cells expressed alpha and gamma in marked excess over beta. Thus, formation of high affinity IL-2R on activated T cells was primarily limited by beta chain expression. In contrast, resting natural killer (NK) cells constitutively expressed IL-2R beta without detectable alpha or gamma. After activation with either IL-2 or IL-12, expression of both alpha and gamma transiently increased and then returned to very low levels. Expression of functional IL-2R on resting and activated NK cells, therefore, appeared to be primarily limited by the expression of gamma chain. IL-2 binding studies with resting NK cells confirmed the results of immunofluorescence studies indicating the presence of very low numbers of intermediate affinity (beta gamma) receptors for IL-2 on these cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Mutagenic analysis of a receptor contact site on interleukin-2: preparation of an IL-2 analog with increased potency

Interleukin-2 (IL-2) is a 133 amino acid alpha-helical protein secreted by activated T-cells. Combinatorial cassette mutagenesis was used to investigate the functional role of a continuous five amino acid region of IL-2 suspected to interact with the intermediate-affinity IL-2 receptor. A limited random library of IL-2 mutants was constructed in which residues 17-21 (Leu-Leu-Leu-Asp-Leu) were simultaneously mutated. The proteins were produced in an Escherichia coli expression system and screened in a biological assay for their ability to mediate the proliferation of a murine IL-2-dependent cell line. From the over 2600 clones examined, only 42 exhibited significant activity, confirming the functional importance of this region. Selected clones were purified and further characterized by biological and receptor binding assays. Viewed in the context of the recently revised 2.5-A crystal structure for IL-2, these results suggest the following conclusions: both Asp20 and Leu21, as shown by their sensitivity to mutation, are the functionally more important residues in this region, but for different reasons. Asp20 is solvent-accessible and likely plays a direct receptor contact role as previous studies have indicated. Leu21, in contrast, is completely buried in the hydrophobic core of the protein. Substitutions at this position, even a conservative Leu-->Val substitution, were found to perturb the precise hydrophobic packing arrangements that are critical for activity, resulting in a significant loss of function. In addition, one of the analogs identified in the screen was found to be 2-3 times more potent than the wild-type protein.

Expression and ligand binding characterization of the beta-subunit (p75) ectodomain of the interleukin-2 receptor

The baculovirus-mediated eukaryotic insect cell expression system was used to prepare large quantities of the beta-subunit ectodomain of the high-affinity interleukin-2 receptor (IL-2R beta x). We describe the expression, purification, and biophysical characterization of this ligand binding domain. The human cDNA encoding IL-2R beta x was inserted into baculovirus transfer vectors. High titer recombinant baculovirus was produced in Spodoptera frugiperda (Sf9) insect cells, and the viral supernatants were subsequently used to infect monolayers of Trichoplusia ni (High Five) insect cells in serum-free culture. Maximal expression of the recombinant protein excreted into the cell culture supernatants was determined by SDS/PAGE analysis, where a band migrating with an apparent molecular mass of 31 kDa was identified by immunostaining. One-step purification was achieved by affinity chromatography on either a monoclonal antibody (TIC-1) column or an IL-2 column, with a final yield of approximately 5 mg/L of culture supernatant. Interestingly, partial purification was also demonstrated using metal chelate affinity chromatography. Amino-terminal sequence analysis of the protein matched the published sequence. Both equilibrium sedimentation analysis and gel filtration chromatography indicated that IL-2R beta x remains monomeric. Deconvolution of far-UV circular dichroism (CD) spectra indicated the predominant secondary structural element to be beta-sheet, consistent with structural analysis and predictions for other members of the hematopoietic receptor family. A dissociation constant (Kd) for IL-2R beta x in solution of 5.3 x 10(-7) M was calculated from competitive receptor binding assays.(ABSTRACT TRUNCATED AT 250 WORDS)

In search of cytokine-response genes

The development of efficient cloning methods for the isolation of cytokine-response genes is vital to our understanding of how cytokines elicit distinct cellular responses. Here, Carol Beadling and Kendall Smith describe a straightforward and rapid method that has been used to clone interleukin 2 (IL-2)-induced genes.

Self-inflicted orbital and intracranial injury with a retained foreign body, associated with psychotic depression: case report and review

Reports of intracranial self-mutilation by psychotic individuals are associated with severe mental disorders, criminality, or both. We describe a psychotically depressed male who drove a ballpoint pen through his right medial canthus and into his intracranial compartment. The patient developed a cavernous sinus syndrome and a traumatic dissection of the cavernous portion of the carotid artery. The pen was removed intraoperatively. Postoperatively, the patient was placed on a course of broad-spectrum antibiotics, antidepressants, and antipsychotic medications, and he has received long-term psychiatric follow-up. The literature related to these unusual cases is reviewed, and relevant surgical, medical, and psychiatric aspects of treatment are discussed.

Tactics for the isolation of interleukin-2-induced immediate-early genes

Interleukin-2 (IL-2), a 15 kDa protein secreted by antigen-activated T lymphocytes, plays a central role in the generation of an immune response. Initially characterized as a T cell growth factor, IL-2 has subsequently been found to act on all lymphoid cell types, inducing both their proliferation and functional differentiation. The effects of IL-2 are mediated by the activation of a specific cell-surface receptor (IL-2R), which is comprised of at least three distinct proteins. Early biochemical signaling events triggered upon IL-2R activation have recently begun to be elucidated, and a number of genes have been identified which are specifically induced by IL-2. The task now at hand is to link the biochemical signaling pathways activated by IL-2 with the regulation of gene expression, and to delineate the roles of these gene products in IL-2-mediated proliferation and differentiation.

Cytokine gene activation and modified responsiveness to interleukin-2 in the blood of tuberculosis patients

Selected parameters of cellular immunity relating to cytokine gene activation and responsiveness to interleukin-2 (IL-2) were analyzed in 27 patients with active pulmonary tuberculosis and no human immunodeficiency virus type 1 infection. Cytokine mRNAs were not expressed by peripheral blood mononuclear cells (PBMC) of normal controls. In PBMC of tuberculosis patients, messages for IL-1, IL-8, and tumor necrosis factor-alpha were uniformly expressed, whereas PBMC of only 5 of 18 patients expressed IL-6. PBMC of 7 patients (all of those with systemic symptoms) expressed interferon-gamma mRNA and none expressed IL-2 mRNA. Most patients' cells demonstrated IL-4 mRNA. Limiting dilution analysis of IL-2-responsive cells in PBMC revealed that tuberculosis patients had 10-fold fewer IL-2-responsive cells than did controls.

Recombinant rat stem cell factor synergizes with recombinant human granulocyte colony-stimulating factor in vivo in mice to mobilize peripheral blood progenitor cells that have enhanced repopulating potential

Splenectomized mice treated for 7 days with pegylated recombinant rat stem cell factor (rrSCF-PEG) showed a dose-dependent increase in peripheral blood progenitor cells (PBPC) that have enhanced in vivo repopulating potential. A dose of rrSCF-PEG at 25 micrograms/kg/d for 7 days produced no significant increase in PBPC. However, when this dose of rrSCF-PEG was combined with an optimal dose of recombinant human granulocyte colony-stimulating factor (rhG-CSF; 200 micrograms/kg/d), a synergistic increase in PBPC was observed. Compared with treatment with rhG-CSF alone, the combination of rrSCF-PEG plus rhG-CSF resulted in a synergistic increase in peripheral white blood cells, in the incidence and absolute numbers of PBPC, and in the incidence and absolute numbers of circulating cells with in vivo repopulating potential. These data suggest that low doses of SCF, which would have minimal, if any, effects in vivo, can synergize with optimal doses of rhG-CSF to enhance the mobilization of PBPC stimulated by rhG-CSF alone.

The development of sequence-tagged sites for human chromosome 4

As part of our efforts to construct a high-resolution physical map of human chromosome 4, we developed a systematic approach for efficiently generating large numbers of chromosome-specific sequence-tagged sites (STSs). In this paper, we describe how rate-limiting steps in our STS development were identified and overcome, and detail our current development strategy. We present information for 822 new human chromosome 4-specific STSs, including PCR amplification conditions and subchromosomal localization data, obtained by analysis of the STS with somatic cell hybrids containing different portions of human chromosome 4. Although most STSs presented here were developed from anonymous clones whose sequences were determined in this laboratory, several STSs were developed for genes and other DNA sequences that were previously mapped to chromosome 4. Our data indicate that the availability of DNA sequence for an STS locus, in addition to the sequences of the two PCR oligonucleotides, significantly increases the transfer of that STS by allowing investigators to select new oligonucleotides best suited to the standard conditions used in their laboratories.

Stem cell factor enhances in vivo effects of granulocyte colony stimulating factor for stimulating mobilization of peripheral blood progenitor cells

Granulocyte colony stimulating factor (G-CSF) has been shown to increase peripheral blood progenitor cells (PBPC) which have an enhanced engraftment potential in autologous transplantation compared with bone marrow cells. The data presented in this study demonstrate the ability of low doses of stem cell factor (SCF) to synergize with G-CSF to enhance the mobilization of PBPC, compared with G-CSF alone, in both mouse and primate models. In the mouse model the combination of SCF plus G-CSF stimulated an absolute increase in cells with in vivo repopulating potential. These studies suggest a possible role for SCF plus G-CSF in the clinical setting for increased mobilization of PBPC, giving rise to increased phoresis yields and enhanced engraftment for support of high-dose chemotherapy.

Thalidomide exerts its inhibitory action on tumor necrosis factor alpha by enhancing mRNA degradation

We have examined the mechanism of thalidomide inhibition of lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-alpha) production and found that the drug enhances the degradation of TNF-alpha mRNA. Thus, the half-life of the molecule was reduced from approximately 30 to approximately 17 min in the presence of 50 micrograms/ml of thalidomide. Inhibition of TNF-alpha production was selective, as other LPS-induced monocyte cytokines were unaffected. Pentoxifylline and dexamethasone, two other inhibitors of TNF-alpha production, are known to exert their effects by means of different mechanisms, suggesting that the three agents inhibit TNF-alpha synthesis at distinct points of the cytokine biosynthetic pathway. These observations provide an explanation for the synergistic effects of these drugs. The selective inhibition of TNF-alpha production makes thalidomide an ideal candidate for the treatment of inflammatory conditions where TNF-alpha-induced toxicities are observed and where immunity must remain intact.