A soluble extract from human spermatozoa activates ascidian oocytes

A soluble extract from human spermatozoa induced calcium oscillations and extrusion of the first polar body when injected into oocytes of the ascidian Ciona intestinalis. The properties of calcium oscillations and time of polar body extrusion precisely mimic oocyte activation induced by C. intestinalis sperm or sperm extracts. The data suggest that human sperm extracts can activate oocytes of different phyla by the same mechanism as homologous spermatozoa. Injection of inositol 1,4,5-trisphosphate (IP3) into C. intestinalis oocytes mimicked to some extent the initial stages of oocyte activation, but the results demonstrate that ascidian oocyte activation by human sperm extract cannot be explained solely in terms of IP3-induced calcium release. Injection of other calcium releasing second messengers, cyclic adenosine diphosphate ribose, or calcium ions, does not lead to oocyte activation or release intracellular calcium in ascidian oocyte. It was concluded that human spermatozoa contain one or more molecules than can trigger intracellular calcium release in oocytes from different phyla.

Down-regulation of protein kinase CKII activity by sodium butyrate

Butyrate, a dietary fiber derivative, is a well-known differentiating agent in cultured cell lines. In addition, its antineoplastic activity toward colon-rectum cancers has been documented both in vivo and in vitro. Despite the large amount of information on the potential clinical efficacy of butyrate, its mechanism of action at the molecular level has only been partially investigated. Here, we show that serine/threonine protein kinase CKII is a target of butyrate activity. In the human adenocarcinoma cell line, HT29, treated with 2 mM sodium butyrate, CKII activity decreases 50% at 24 and 48 hours after drug addition. The enzyme down-regulation is not due to changes in protein amount since the levels of the different CKII subunits remain constant during butyrate treatment. The data reported provide the first evidence that CKII down-regulation is involved in the signal transduction pathway started by butyrate.

Biochemical characterization of p16INK4- and p18-containing complexes in human cell lines

The regulation of the D-type cyclin-dependent kinase (CDK4 and CDK6) activity appears to be the key step in the progression of eukaryotic cells through the G1 cell cycle phase. One of the mechanisms involved in this process is the binding of some small proteic inhibitors, with a molecular mass ranging between 14 and 20 kDa, to these CDKs. We have evaluated the amount of two such inhibitors, namely p16(INK4) and p18, in normal and transformed cells, as well as the biochemical features of the macromolecular complexes containing these proteins. The results obtained indicated that (i) p18 gene expression, unlike p16(INK4) gene, is not regulated by pRb status, (ii) no evident relationship exists between the expression of p16(INK4) and p18 genes, (iii) significant amounts of the two proteins are not bound to CDKs but occur as free molecules, (iv) each inhibitor forms a complex with the CDK protein with a 1:1 stoichiometry, and (v) a competition exists between cyclin D and the inhibitor protein toward the CDK protein resulting in the absence of detectable cellular free kinase. Moreover, employing the human native partially purified p16(INK4)or the pure recombinant protein, we have been able to demonstrate in vitro the dissociation of CDK4-cyclin D1 complex and the formation of CDK4-p16(INK4) bimolecular complex. Our findings suggest that during the cell division cycle the members of the p16(INK4) protein family and cyclin Ds compete for binding to CDK4/CDK6 and that their quantitative ratio is essential for G1 --> S transition.

Maturation promoting factor in ascidian oocytes is regulated by different intracellular signals at meiosis I and II

Using the fluorescent dye Calcium Green-dextran, we measured intracellular Ca2+ in oocytes of the ascidian Ciona intestinalis at fertilization and during progression through meiosis. The relative fluorescence intensity increased shortly after insemination in a single transient, the activation peak, and this was followed by several smaller oscillations that lasted for approximately 5 minutes (phase 1). The first polar body was extruded after the completion of the phase 1 transients, about 9 minutes after insemination, and then the intracellular calcium level remained at baseline for a period of 5 minutes (phase 2). At 14 minutes postinsemination a second series of oscillations was initiated that lasted 11 minutes (phase 3) and terminated at the time of second polar body extrusion. Phases 1 and 3 were inhibited by preloading oocytes with 5 mM heparin. Simultaneous measurements of membrane currents, in the whole-cell clamp configuration, showed that the 1–2 nA inward fertilization current correlated temporally with the activation peak, while a series of smaller oscillations of 0.1-0.3 nA amplitude were generated at the time of the phase 3 oscillations. Biochemical characterization of Maturation Promoting Factor (MPF) in ascidian oocytes led to the identification of a Cdc2-like kinase activity. Using p13suc1-sepharose as a reagent to precipitate the MPF complex, a 67 kDa (67 × 10(3) Mr) protein was identified as cyclin B. Histone H1 kinase activity was high at metaphase I and decreased within 5 minutes of insemination reaching a minimum level during phase 2, corresponding to telophase I. During phase 3, H1 kinase activity increased and then decayed again during telophase II. Oocytes preloaded with BAPTA and subsequently inseminated did not generate any calcium transients, nonetheless H1 kinase activity decreased 5 minutes after insemination, as in the controls, and remained low for at least 30 minutes. Injection of BAPTA during phase 2 suppressed the phase 3 calcium transients, and inhibited both the increase in H1 kinase activity normally encountered at metaphase II and second polar body extrusion.

Purification and characterization of recombinant human 5'-methylthioadenosine phosphorylase: definite identification of coding cDNA

5'-Methylthioadenosine phosphorylase gene maps on the 9p21 chromosome, strictly linked to the important tumor suppressor gene p16INK4A. Chromosomal deletions encompassing both the phosphorylase and p16INK4A genes cause the complete absence of the enzymatic activity in a large number of tumors, thus resulting in well-defined metabolic differences between malignant and normal cells. Recently, the cloning of the phosphorylase gene has been reported on the basis of indirect evidence. In order to demonstrate definitely the identification of 5'-methylthioadenosine phosphorylase gene, we have cloned the putative enzyme coding sequence in a prokaryotic expression vector and expressed the protein in bacteria. The recombinant phosphorylase has been purified to homogeneity and its physicochemical, immunological and kinetic features have been characterized. The results obtained allowed the conclusive demonstration of 5'-methylthioadenosine phosphorylase gene cloning and the use of recombinant protein for further characterization.

Stereo-electroencephalography methodology: advantages and limits

Since January 1990, 70 patients with medically intractable partial epilepsy underwent a stereo-EEG investigation in our center. We first described technical requirements, and gave an overview of the variety of the explored cerebral regions and implantation patterns realized, pointing out the low rate of morbidity (1.4%). The three-dimensional epileptogenic zone thus defined led to a tailored individualized surgical excision in 60 patients, while 9 are waiting for surgery and the remaining 1 has been excluded (1.4%). Conceptual and technical aspects of the stereo-EEG methodology were discussed in order to underline its peculiarities in the field of "depth recordings", and more generally among the broader group of "invasive" procedures.

[Electroclinical manifestations elicited by intracerebral electric stimulation "shocks" in temporal lobe epilepsy]

In patients with severe drug-resistant partial epilepsy, undergoing Stereo-EEG investigations, spatial definition of the "epileptogenic area" is mainly based on spontaneous seizures recordings, but also on seizures induced by intracerebral electrical stimulation (ES). Only "trains" ES (TES, 50 pps) are currently used with this aim; "shocks" ES (SES, 1 pps) are principally applied to localize motor pathways. We have shown, during a prospective study concerning 10 temporal lobe epileptic patients, that SES could frequently induce seizures, especially when stimulation is applied in the anterior part of the Ammon's horn. Even if its efficacy seems lower than by TES, this kind of stimulation, in the majority of the cases, does reproduce isolated ictal subjective symptomatology, allowing the visualization of the progressive organisation of ictal electrical discharges, and avoids "unexpected" ("false positive"?) clinical responses.

Intracerebral low frequency electrical stimulation: a new tool for the definition of the "epileptogenic area"?

Low Frequency (1 Hz) Electrical Stimulation (LFES) has been systematically utilized, during stereo-EEG investigations, in 24 consecutive young adult patients considered for surgical treatment of severe drug-resistant partial epilepsy. Ninety seizures (1-14/patient) identical to the spontaneous ones previously recorded were thus obtained in 19 patients (79%). LFES is less effective for induction of seizures than high frequency (50 Hz) stimulation (5.9% vs 22.9%), and it also provokes less "false positive" responses (1% vs 17%). The main "sensitive" structures to LFES are the hippocampus, the amygdala, and the hippocampal gyrus. However, seizures were also induced by stimulating the temporal lobe white matter, the temporal pole, and the temporal neocortex, as well as the orbito-frontal cortex (in the only patient with fronto-temporal epilepsy). The more frequently observed electrical pattern is a gradual increase of spikes and spikes and waves frequency, with or without occurrence of low voltage fast activity. The high percentage of early "subjective" manifestations similar to the spontaneous ones, the lack of major electrical artifact, and the good visualization of the spatial evolution of the induced-discharge, strongly suggest that LFES is of great help for defining the "epileptogenic area".

Casein kinase II phosphorylates p34cdc2 kinase in G1 phase of the HeLa cell division cycle

The activity of p34cdc2 kinase is regulated in the phases of vertebrate cell cycle by mechanisms of phosphorylation and dephosphorylation. In this paper, we demonstrate that casein kinase II (CKII) phosphorylates p34cdc2 in vivo and in vitro at Ser39 during the G1 phase of HeLa cell division cycle. Human p34cdc2 shows a typical phosphorylation sequence motif site for CKII at Ser39 (ES39EEE). In our experiments, either p34cdc2 expressed and purified from bacteria or p34cdc2 immunoprecipitated from HeLa cells enriched in G1 by elutriation were substrates for in vitro phosphorylation by CKII. Phosphoamino acid analysis, N-chlorosuccinimide mapping, and two-dimensional tryptic mapping of p34cdc2 phosphorylated in vitro were performed to determine the phosphorylation site. A synthetic peptide spanning residues 33-50 of human p34cdc2, including the CKII site, was used to map the site. In addition, phosphorylation at Ser39 also occurs in vivo, since p34cdc2 is phosphorylated during G1 on serine, and its two-dimensional tryptic map shows two phosphopeptides that comigrate exactly with the synthetic peptides used as standard.

Stereotactic approach to intracranial lesions

The diagnostic and therapeutic approach to intracranial lesions must be different considering the different possibilities offered by the various methods. The diagnostic reliability and safety of stereotactic biopsy are often indispensable in order to optimize the subsequent therapy. The results obtained in selected pathologies allow us to propose the stereotactic approach to treat: -various kind of cysts by aspiration and/or Beta endocavitary radiation therapy; -blood or abscessual collections that can be aspirated in a similar way; -arterio venous malformations or tumours by radiosurgery; -tumours by brachicurietherapy or by computer assisted stereotactic surgery. We present some cases treated at the C.H.S.A. of Paris and at the C.H.R.U. of Grenoble utilizing Talairach methodology.

Deficiency of 5'-deoxy-5'-methylthioadenosine phosphorylase activity in malignancy. Absence of the protein in human enzyme-deficient cell lines

The absence of 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAase) activity in malignant cells, and the putative localization of its gene, suggest that this enzyme deficiency might be due to a genomic alteration also involving a tumour-suppressor gene. We studied the possible occurrence of inactive forms of the protein in two MTAase-negative cell lines, namely K562 and Jurkat, by immunochemical methods. Two highly specific antisera, directed against different epitopes of the phosphorylase [Della Ragione, Oliva, Gragnaniello, Russo, Palumbo & Zappia (1990) J. Biol. Chem. 265, 6241-6246], were used to carry out immunotitration and immunoblotting analyses, as well as to investigate the biosynthesis of the enzyme. No MTAase protein was detected by Western-blotting technique performed under conditions where all the phosphorylase-positive samples gave a clear band at the MTAase subunit molecular mass. No cross-reacting material was observed by a sensitive immunotitration method which permitted the detection of as low as 0.5 ng of protein. Moreover, the results obtained by [35S]methionine-labelling experiments ruled out phosphorylase biosynthesis in the negative cell lines. Altogether, these data suggest that an alteration at the gene level hampering the specific mRNA biosynthesis or resulting in an untranslatable mRNA is the cause of the enzyme deficiency in the MTAase-negative cell lines studied.

Physicochemical and immunological studies on mammalian 5'-deoxy-5'-methylthioadenosine phosphorylase

5'-Deoxy-5'-methylthioadenosine phosphorylase (MTAase) was purified to homogeneity (10,000-fold) from bovine liver with a recovery of 12%. The pure protein shows a molecular weight of about 98,000 +/- 3,000 and is composed of three apparently identical subunits. Several physicochemical features have been investigated including hydrodynamic properties, amino acid composition, and secondary structure. In particular, the CD spectrum of the protein indicates a very low alpha-helical content and a large percent of beta-structure and random coil. The pure protein was used to raise specific rabbit antisera but, because of the scarce antigenic properties of the native enzyme, different chemically modified forms were prepared and employed as immunogens. Among the antibodies obtained, those to keyhole limpet hemocyanin-MTAase recognize both the native and the denatured enzyme and are also active against the human protein. Therefore, they were employed as a tool to investigate the occurrence of inactive forms of MTAase in two human malignant cell lines lacking this enzymatic activity. The results obtained with K562 and Jurkat cells indicate that the protein is absent in these phosphorylase-deficient cell lines.

Electromyographic abnormalities in redundant nerve root syndrome of the cauda equina

This report documents the seventh patient with redundant nerve root syndrome of the cauda equina in which electromyographic abnormalities were reported. A 79-year-old woman developed low back pain radiating into the left lower extremity. Electromyography (EMG) revealed partial denervation of the left medial gastrocnemius muscle. Metrizamide myelography disclosed a complete block of the spinal canal at the L3 vertebral level, and a coiled nerve root was present behind the L2 vertebral body. Computed tomography showed marked spondylotic narrowing of the spinal canal at the L3 to L4 vertebral level, and spinal stenosis at the L4 to L5 vertebral level. An L3 laminectomy revealed nodular bony overgrowth and ligamentous hypertrophy compressing the dura. Postoperatively, the patient experienced significant pain relief and increased ambulation ability. Electromyographic abnormalities in the left medial gastrocnemius muscle were still present at three- and six-month follow-up.

Peripheral neuropathy after concomitant dimethyl sulfoxide use and sulindac therapy

The case is presented of a 63-year-old man with a long history of degenerative arthritis who took sulindac (Clinoril) 200 mg BID for 6 months with no untoward effects. Then, without physician knowledge, he began using 90% dimethyl sulfoxide (DMSO) topically to his upper and lower extremities. Shortly thereafter, he developed a profound mixed sensorimotor peripheral neuropathy. Serial electromyographic and nerve conducion studies performed at intervals of several months for 1 year suggested both segmental demyelination and axonal neuropathy. The patient experienced initial deterioration followed by gradual but incomplete recovery.

The radiologic "Target sign" of septic pulmonary embolism in a case of acute myelogenous leukemia

The authors report the appearance of septic pulmonary embolism in a case of acute myelogenous leukemia. The pulmonary lesions are characterized radiographically by the uncommon appearance of central densities suspended within thin-walled pseudocystic air spaces. A possible pathogenic mechanism explaining these radiographic findings is discussed. Such images must be distinguished from those of a fungus ball or tuberculous cavities.