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Biomedical subjects

N E Williams

Publications and source records attributed to N E Williams.

At least 19 recordsLinked to original sources
PubMed1991

Is Cyclin Zeuthen's "division protein"?

Biochemical evidence is presented for the presence of cyclin in Tetrahymena. Zeuthen previously postulated the existence of a heat-labile "division protein" to explain heat-shock-induced division synchrony in Tetrahymena [(1964) Synchrony in Cell Division and Growth (Zeuthen, E., Ed.), pp. 99-158, Interscience, New York]. We show that cyclin is heat-labile in Tetrahymena and suggest that cyclin may be Zeuthen's division protein. Cyclin and cell cycle control is of interest in Tetrahymena because the division mechanism drives macronuclear amitosis, closed and acentric micronuclear mitosis, and cortical differentiation in this cell type.

Animals↗
PubMed1990

Plasma concentrations of bupivacaine after stellate ganglion block using two volumes of 0.25% bupivacaine plain solution.

Plasma concentrations of bupivacaine were measured in patients after stellate ganglion block using either 10 or 20 ml of 0.25% plain solution. The mean peak concentrations were greater in the larger volume group, but this was not statistically significant. From 30 min after injection, there was a significantly greater plasma concentration in the larger volume group. The concentrations approached the limit of detection in the smaller volume group at 2 h after block.

Anesthesia, Local↗
PubMed1990

The formation of basal body domains in the membrane skeleton of Tetrahymena.

Differentiated regions within the membrane skeleton are described around basal bodies in the ciliary rows of Tetrahymena. These domains, approximately 1 micron in diameter, are characterized by a relatively dense ultrastructure, the presence of a family of proteins called K antigens (Mr 39-44 x 10(3)) that are recognized by mAb 424A8, and the apparent exclusion of major membrane skeleton proteins that are present in most other regions of the cell (Mr 135, 125 x 10(3]. Mature basal body domains are asymmetric, reflecting the polarity of the cell as a whole. A similar differentiation of the membrane skeleton occurs in the oral apparatus, except here the K antigens surround four clusters of basal bodies (from which this cell takes its name) rather than the individual basal bodies. The development of new basal body domains in the cell cycle is described, with similarities and differences noted between somatic and oral regions of the cell. It is concluded that the capacity of this cell for precise topographic regulation of molecular events in the membrane skeleton makes it a useful model for the study of cortical differentiation in cells generally.

Animals↗
PubMed1990

Tetrins: polypeptides that form bundled filaments in Tetrahymena.

The cortex of the ciliated protozoan Tetrahymena contains a number of fibrous elements, including a network of filaments that pervades the feeding organelle of this organism. The cluster of polypeptides (79-89K; K = 10(3) Mr) in Tetrahymena pyriformis GL-C that constitute these filaments has been purified by in vitro assembly after solubilization in 1.0 M KI. Four distinct sets of these polypeptides, designated 'tetrins', have been shown to be distinguishable from each other by immunochemical and biochemical criteria. The smallest filaments reassembled in vitro were 3-4 nm in diameter and these fine filaments were seen to be bundled together into thicker strands of varying diameters, similar to those within the cell. The thicker filament bundles were clearly distinguishable from intermediate filaments, but fine filaments in these bundles were superficially similar to the 2-5 nm filaments described as microtubule-associated proteins in other organisms. The ultrastructure of the tetrin filaments localized within the feeding organelle reveals a substantial presence of these filaments apart from microtubules. In addition, circular dichroism measurements indicate a relatively low alpha-helical content for these filaments and suggest that the tetrins may be substantially different from other fine filament proteins such as the tektins and giardins.

Amino Acids↗
PubMed1989

Structure-activity studies of trichothecenes: cytotoxicity of analogues and reaction products derived from T-2 toxin and neosolaniol.

Forty-two analogues and reaction products derived from T-2 toxin or neosolaniol were assayed for their cytotoxicity to cultured mouse lymphoma cells. Structure-activity relationships confirmed the stereospecific nature of the cytotoxic action of T-2. Cytotoxicity was particularly susceptible to changes at C3, C4, C9, and C10 but was relatively unaffected by changes at C8, which appears to represent a region of steric tolerance in the interaction of T-2 with a cellular constituent. The most potent compounds were T-2, diacetoxyscirpenol, and a series of C8 ester analogues 11 and 31-35.

Animals↗
PubMed1989

Properties of microtubule-free cortical residues isolated from Paramecium tetraurelia.

We have found that shape-preserving residues devoid of microtubules can be prepared from Paramecium using Triton X-100 at high ionic strength. These residues contain many proteins, including one showing antigenic relationship to chicken alpha-spectrin, and three showing antigenic relationship to Tetrahymena cortical proteins. These antigens have been localized by immunofluorescence microscopy, and the isolated cortical residues have been characterized ultrastructurally. These preparations should be useful in detailed studies of the structure, development and evolutionary relationships of cortical architecture in ciliated protozoa.

Animals↗
PubMed1989

Identification and localization of major cortical proteins in the ciliated protozoan, Euplotes eurystomus.

Shape-preserving cortical residues have been isolated from Euplotes eurystomus cells by the application of Triton X-100 at high ionic strength. These integrated structures consist of articulated plates and widely interspersed cages that formerly contained basal bodies associated with the clusters of cilia characteristic of this cell type. Using SDS-PAGE and immunolocalization procedures, we have identified major subunit proteins of both the plates (116, 110 (X10(3] Mr, and the basal body cages (86 X 10(3) Mr). The potential for studies of these proteins in contributing to our understanding of cortical development and evolution in Euplotes is discussed.

Animals↗
PubMed1989

Spread of local anaesthetic solutions following sacral extradural (caudal) block: influence of posture.

Extradural sacral (caudal) block was performed in 17 cases (14 patients) of chronic low back pain. In each case 22 ml of a bupivacaine/methylprednisolone solution incorporating a radioopaque dye was injected over a 2-min period. Patients were randomly assigned to receive the injection in the horizontal position or with 15 degrees head-up or head-down tilt applied to the operating table. Results indicate that analgesia is usually more localised than spread of solution determined by x-ray evidence and that higher levels of analgesia are achieved in patients in the head-up position. Possible causes are the differing distribution characteristics of the constituents of the solution and the gravitational effects of posture on cerebrospinal fluid mechanics. Technical problems associated with obesity, congenital abnormalities, vascular uptake of solution, and delayed spread of the injectant due to adhesions are discussed.

Anesthetics, Local↗
PubMed1988

Differential effects of neuromuscular blocking agents on suxamethonium-induced fasciculations and myalgia.

The effect of pretreatment with suxamethonium, gallamine or pancuronium on suxamethonium-induced fasciculations and myalgia was studied in a controlled, randomized and double-blind clinical trial. Both fasciculations and myalgia were assessed on a four-point rating scale. There was no significant correlation between fasciculations and postoperative muscle pain at 24, 48 or 72 h, and pretreatment with suxamethonium had no significant effect on fasciculations or myalgia. Gallamine had a more marked effect on fasciculations than pancuronium, and the decrease in the fasciculation score was statistically significant. In contrast, pancuronium had a greater effect on myalgia, and decreased postoperative muscle pain significantly at 24 and 48 h. These differences may reflect the differential activity of gallamine and pancuronium at the neuromuscular junction. Pretreatment had little or no effect on plasma potassium concentrations.

Adolescent↗
PubMed1987

The assembly and positioning of cytoskeletal elements in Tetrahymena.

The oral skeleton of Tetrahymena is a precisely arranged assemblage of basal bodies, microtubule bundles and connecting filaments found associated with the feeding structure in this cell type. Tubulin and filament proteins have been isolated but no actin has been recovered. The conditional mutant NP1 of Tetrahymena thermophila forms a normal oral skeleton at the permissive temperature (28 degrees C), but forms an abnormal one at the restrictive temperature (37 degrees C). Antibodies against tubulin and oral filament protein OF1 were used to visualize the abnormal oral skeleton and stages in its development, and ultrastructural comparisons of abnormal and wild-type oral skeletons were made. It was found that the overall pattern of organization was altered in the mutant, whereas the substructure appeared everywhere to be normal. Studies of cells in which the mutant phenotype was coming to expression revealed that normal basal bodies in the oral skeleton failed to move from the disordered state characteristic of early stages of development into the correct pattern of four organized clusters characteristic of later stages. Together, these results suggest that the lesion in NP1 does not affect cytoskeleton assembly per se, but instead affects a discrete mechanism responsible for the positioning of cytoskeletal elements with respect to each other after they have been formed (meta-assembly). Reasons for suspecting the involvement of the membrane skeleton are presented.

Animals↗
PubMed1987

Regional differentiation of the membrane skeleton in Tetrahymena.

Antisera have been raised in rabbits against three high molecular weight proteins that are present in Triton X-100-insoluble residues of Tetrahymena pyriformis GL cells. These proteins, called A, B and C, have apparent molecular weights of 235, 135 and 125 (X 10(3)), respectively, in SDS-polyacrylamide gels. The antisera obtained are specific for these proteins, as shown by immunoblotting. Immunolocalization studies are reported that suggest that these proteins are present throughout the epiplasmic layer beneath the cell surface (membrane skeleton). Images obtained with the fluorescence microscope, however, suggest that the membrane skeleton is modified in discrete zones: (1) around somatic basal bodies, (2) within the oral apparatus, (3) in the cytoproct, (4) in contractile vacuole pores, (5) in the fission zone in late division, and (6) at the mating junction in conjugating cells. These regions may represent areas of increased rigidity at the cell surface. The transition from pliable to rigid epiplasm in spatially delimited areas is apparently a recurring theme in cortical morphogenesis in Tetrahymena. Together, the two types of epiplasm probably allow for extensive changes in cell shape while preserving essential relationships between structural elements within the cortex.

Animals↗
PubMed1986

Oral filament proteins and their regulation in Tetrahymena pyriformis.

Two proteins from the Triton X-100-insoluble fraction of Tetrahymena pyriformis have been isolated and shown by immunological methods to be major components of a pervasive system of filaments localized within the oral apparatus. These proteins, OF-1 and OF-2, have apparent molecular weights (MWapp) in polyacrylamide gels of 87,000 and 80,000 D, respectively. Peptide maps obtained and the absence of immunological cross-reactivity suggest that these proteins are not closely related to each other. Indirect immunofluorescence studies on dividing cells have shown that the oral filament system forms late in the cell cycle. The filaments appeared first after the basal bodies in the oral primordium had organized into groups and the fission furrow had begun to form. Dedifferentiation of the oral filament system in the anterior (old) oral apparatus was also observed at this point in the cell cycle. Following this, the oral filament systems in both old and new oral apparatuses completed development synchronously. Proteins showing antigenic similarity to OF-1 were found in a number of other cell types. Tests with heterologous antisera failed to demonstrate a relationship between vertebrate cytoskeletal proteins and the oral filament proteins of Tetrahymena.

Animals↗
PubMed1985

Buccal morphine--a new route for analgesia?

The analgesic effects of buccal and intramuscular morphine were compared in a prospective, double-blind, double-dummy study in forty patients who experienced pain after elective orthopaedic operations. Each patient simultaneously received a buccal tablet and an intramuscular injection, only one of which contained morphine sulphate (13.3 mg); the patients were randomly allocated to two equal groups so twenty patients received each active preparation. The two preparations produced a similar degree of postoperative analgesia, assessed by the mean reduction in pain score and the pain relief score. Peak plasma morphine concentrations were slightly lower after buccal than after intramuscular administration but they declined more slowly; consequently, the drug's bioavailability was 40-50% greater after buccal than after intramuscular administration. The adverse effects of buccal morphine were generally less than those of intramuscular morphine.

Administration, Oral↗
PubMed1985

Postoperative analgesia with Duromorph.

The analgesic effects and bioavailability of a slow-release preparation of morphine (Duromorph) were studied in 12 patients with acute postoperative pain. Duromorph produced significant analgesia within 1-2 h of administration i.m., and there was a progressive decrease in the mean pain score for at least 8 h. None of the patients requested or received additional analgesia within 12 h, and the incidence of side-effects was similar to that associated with i.m. morphine. During the 8-h study, plasma concentrations of morphine slowly increased for 3 h, and then gradually declined. After 3 h, concentrations were invariably greater than those produced by conventional doses of morphine sulphate i.m. The study confirmed that Duromorph was an effective analgesic with a prolonged duration of action, which was suitable for the management of postoperative pain.

Adult↗
PubMed1985

Expression of a cell surface immobilization antigen during serotype transformation in Tetrahymena thermophila.

A temperature shift from 40 to 28 degrees C rapidly induced expression of a specific immobilization antigen at the cell surface in Tetrahymena thermophila. This transformation was inhibited by actinomycin D and cycloheximide but not by colchicine or cytochalasin B. The major surface antigen expressed at 28 degrees C in cells homozygous for the SerH3 allele was partially purified, and an antiserum against this preparation was raised in rabbits. Electrophoresis, immunoblot, and [35S]methionine incorporation studies are reported which support the conclusion that the H3 antigen is an acidic protein with an Mr of approximately 52,000 daltons. An induced synthesis of the H3 immobilization antigen was detected within 30 min after a shift from 40 to 28 degrees C. This protein appeared to be synthesized in the microsomal fraction and transferred without cleavage to the cell surface, where it was inserted first into nonciliated regions.

Animals↗
PubMed1985

Prolonged release extradural morphine.

The effects of extradural administration of a microcrystalline preparation of morphine (Duromorph) were studied in 5 patients with postoperative or malignant pain. As assessed by pain scores on a visual analogue scale, the effects of the analgesic were extremely variable; the best results were obtained in patients with postoperative pain. Two patients with chronic pain due to malignant disease developed slow respiratory rates. The plasma concentration of morphine usually followed a biphasic pattern; an initial peak between 0.5 and 1.5 hours was succeeded by a second, large peak between 6 and 12 hours. There was little or no apparent relation between the plasma concentration of morphine and the relief of pain, suggesting that Duromorph may have a local effect on the spinal cord.

Aged↗