Search PubMed⌕ Search

Biomedical subjects

C J Jones

Publications and source records attributed to C J Jones.

At least 199 records · Page 11Linked to original sources
PubMed1989

L-, P-, and M-ring proteins of the flagellar basal body of Salmonella typhimurium: gene sequences and deduced protein sequences.

The flgH, flgI, and fliF genes of Salmonella typhimurium encode the major proteins for the L, P, and M rings of the flagellar basal body. We have determined the sequences of these genes and the flgJ gene and examined the deduced amino acid sequences of their products. FlgH and FlgI, which are exported across the cell membrane to their destinations in the outer membrane and periplasmic space, respectively, both had typical N-terminal cleaved signal-peptide sequences. FlgH is predicted to have a considerable amount of beta-sheet structure, as has been noted for other outer membrane proteins. FlgI is predicted to have an even greater amount of beta-structure. FliF, as is usual for a cytoplasmic membrane protein of a procaryote, lacked a signal peptide; it is predicted to have considerable alpha-helical structure, including an N-terminal sequence that is likely to be membrane-spanning. However, it had overall a quite hydrophilic sequence with a high charge density, especially towards its C terminus. The flgJ gene, immediately adjacent to flgI and the last gene of the flgB operon, encodes a flagellar protein of unknown function whose deduced sequence was hydrophilic and may correspond to a cytoplasmic protein. Several aspects of the DNA sequence of these genes and their surrounds suggest complex regulation of the flagellar gene system. A notable example occurs within the flgB operon, where between the end of flgG (encoding the distal rod protein of the basal body) and the start of flgH (encoding the L-ring protein) there was an unusually long noncoding region containing a potential stem-loop sequence, which could attenuate termination of transcription or stabilize part of the transcript against degradation. Another example is the interface between the flgB and flgK operons, where transcription termination of the former may occur within the coding region of the latter.

Amino Acid Sequence↗
PubMed1989

Dye-coupling compartments in the human eccrine sweat gland.

The dye-coupling status of secretory and reabsorptive cells in micro-dissected lengths of human eccrine sweat gland was investigated by means of intracellular microiontophoresis of the fluorescent naphthalimide dye Lucifer yellow CH (Mr 457), which passes through gap junctions. Cells of the reabsorptive duct exhibited complete dye coupling between the apical and basal layers of the epithelium. Conversely, cells of the secretory tubule exhibited selective dye coupling. Of the three cell types present, clear, dark, and myoepithelial, the dark cells were impaled and labeled almost exclusively in the present study. These cells were observed either as single cells or as dye-coupled groups of neighboring dark cells. In no instance were dark cells observed to be dye coupled to clear cells or to myoepithelial cells. Because myoepithelial cells are known to be dye coupled exclusively to neighboring myoepithelial cells, the remaining clear cells must either be uncoupled or show selective dye coupling to neighboring clear cells. The significance of these findings is considered with respect to the regulation and function of the different cell types present in the human eccrine sweat gland.

Adult↗
PubMed1989

Saccharide expression on wounded endothelial cell monolayers in vitro.

Monolayer cultures of porcine aortic endothelial cells were used as a model of the endothelium of large arteries. Linear wounds were produced in such cultures by scraping and the subsequent sequence of events in nearby cells was analysed. The earliest detectable event was cellular spreading at the margins of the wounds (2 h) followed by cell migration (starting at 6-8 h) and cell proliferation in regions adjacent to the wound (16 h and later). Cell spreading was associated with the appearance of saccharides selectively at the spreading margins of the cells, which bound the lectins, ConA, LCA and PSA, and were sensitive to alpha-mannosidase. Terminal alpha-mannosyl residues were therefore present. The appearance of these saccharides suggests a mechanism by which monocytes might adhere to and/or migrate through the endothelium of vessels at sites of cellular response to injury.

Animals↗
PubMed1988

Purification and Na+ uptake by human placental microvillus membrane vesicles prepared by three different methods.

Three methods were used to prepare microvillus membrane vesicles from each of six human placentas. Two of these incorporated an agitation stage to preferentially remove microvilli and either Ca2+ (Method 1) or Mg2+ (Method 2) aggregation of non-microvillus membrane. The third method involved homogenisation of the tissue followed by Mg2+ aggregation of non-microvillus membrane (Method 3). Enrichment of alkaline phosphatase activity (27.6 +/- 1.9, 25.3 +/- 2.7) and ouabain binding (5.9 +/- 2.6, 5.3 +/- 2.2, respectively) was similar in vesicles prepared by Methods 1 and 2, respectively. Method 3 vesicles showed a significantly (P less than 0.01) lower alkaline phosphatase enrichment (18.1 +/- 1.2), but ouabain binding enrichment (6.3 +/- 1.3) was not different and vesicle protein recovery (mg/g placenta) was 5-fold greater. Na+ uptake in the presence of an outwardly directed proton gradient was significantly inhibited in all microvillus membrane vesicles by amiloride (0.5 mM). However, the amiloride sensitive component of Na+ uptake was 3-6-fold greater in Method 3 vesicles than in Method 1 and 2 vesicles, and showed overshoot above equilibrium in the former but not the latter. Further experiments using the pH sensitive dye, 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein suggested that the proton gradient dissipated faster from Method 1 than from Method 3 vesicles. Thus methodological differences can have a marked effect on transport processes in microvillus membrane vesicles prepared from the human placenta.

Alkaline Phosphatase↗
PubMed1988

An ultrastructural study of the morphology and lectin-binding properties of human mast cell granules.

The morphological characteristics and lectin-binding properties of mast cell granules from four human neurofibromata are described. Ultrastructural examination of the granules revealed that some contained dense cores, others had membranous configurations and some forms were intermediate between the two. A round electron-lucent area was present in some granules. After treatment with biotinylated lectins (10 micrograms ml-1) followed by an avidin-peroxidase revealing system (5 micrograms ml-1 in 0.125 M Tris-buffered saline with 0.347 M NaCl, pH 7.6), mast cell granules strongly bound Concanavalin A, garden pea, lentil, wheatgerm, erythro- and leuco-kidney bean lectins. This indicated the presence of abundant N-linked complex-type saccharide sequences. Soybean and peanut lectins showed only weak binding, while the presence of sparse alpha-L-fucosyl terminals was indicated by the weak binding of winged pea lectin. The staining intensity of wheatgerm lectin was considerably reduced when incubated in the presence of its specific competing sugar tri-N-acetylchitotriose. Despite a wide variety of morphological differences between granules, all showed similar staining patterns and all granules within a single cell shared the same binding characteristics.

Cytoplasmic Granules↗
PubMed1988

Lectin histochemistry of the mast cell: a light microscopical study.

The purpose of this study was to determine if human mast cell granules contain non-repeating oligosaccharide sequences. The binding of lectins to human mast cell granules was studied using a panel of 11 lectins variously selective for both N- and O-linked oligosaccharide sequences. The tissues were principally derived from cutaneous neurofibromata and benign and malignant breast diseases, that is, readily available human material with a known high content of mast cells. Lectin-binding sites in the formalin-fixed paraffin-embedded or resin-embedded material was visualized by means of biotinylated lectins and an avidin-peroxidase technique for light microscopy. The results indicate that human mast cell granules contain abundant N-linked sequences, but few or no O-linked residues. These sequences appear to be mostly in the form of non-bisected highly branched or smaller biantennate sequences, although variable positive binding with erythrophytohaemagglutinin was observed, indicating some degree of bisection.

Histocytochemistry↗
PubMed1988

What stops the flow of blood from the heart?

The determinants of aortic pressure and flow are generally studied using impedance methods, the results of which indicate that reflected waves are important, particularly during aortic flow deceleration. An alternative analysis of measured aortic pressure and velocity, using the method of characteristics to calculate the energy flux per unit area of the waves, suggests a different conclusion. We suggest that aortic deceleration is caused by a discrete expansion wave propagating from the left ventricle, and that energy thus recovered by the ventricle may be coupled to early filling of the ventricle.

Aorta, Thoracic↗
PubMed1988

Effects of atropine and glycopyrrolate on neuromuscular transmission in the rat phrenic nerve-diaphragm preparation.

1. The effects of atropine and glycopyrrolate on neuromuscular transmission and on muscle contraction, were studied, in the rat diaphragm preparation, by analyzing their effects on the indirectly (and directly)-elicited twitch (0.2 Hz), tetanic (50 Hz for 20 sec duration), post-tetanic twitch responses (at 5 sec after the tetanus), and on the phenomenon of post-tetanic twitch potentiation (PTP), which is thought to be of a presynaptic origin, i.e. due to increased transmitter release. 2. Atropine (0.001-10 microM) increased the indirectly-elicited twitch tension by 22 +/- 2.1% (control 0.9 +/- 0.1 g, P less than 0.02), the tetanus by 15 +/- 1.1% (control 3.9 +/- 0.7 g, P less than 0.05), the post-tetanic twitch response by 33 +/- 3.1% (control 1.2 +/- 0.1 g, P less than 0.01) and the PTP value by 36 +/- 1.9% (control 33 +/- 2.3%, P less than 0.01, means +/- SEM = 6). 3. Atropine (0.001-10 microM) had little effect on the directly-elicited twitch tension, but in high concentrations (e.g. 20 microM), it blocked the twitch tension. 4. In contrast, glycopyrrolate (0.1-100 microM) had little effect on the twitch tension (direct or indirect), but it significantly reduced the tetanus (by 38 +/- 3.5%, P less than 0.01), the post-tetanic twitch response (by 17 +/- 1.2%, P less than 0.05) and the PTP values (by 24 +/- 3.1% P less than 0.02). 5. In the presence of hemicholinium (1.3 microM) the responses to atropine and glycopyrrolate were altered (decreased), indicating a possible action on presynaptic mechanism of transmission. 6. It is concluded that atropine and glycopyrrolate produce different (opposite) effects at the rat neuromuscular junction, atropine enhances whereas glycopyrrolate depresses neuromuscular transmission. The effects of these two antimuscarinic drugs may be exerted at the presynaptic nerve terminals, i.e. on presynaptic muscarinic receptors, which are involved in the feedback mechanism of transmitter release.

Animals↗
PubMed1988

Intravenous nifedipine for control of hypertension in patients after coronary artery bypass graft surgery.

A study was undertaken to assess the use of intravenous nifedipine in controlling hypertension in patients following coronary artery surgery. A combined hemodynamic and metabolic assessment was carried out in 15 patients on data recorded at six sequential time intervals: (1) baseline, (2) control of blood pressure, (3) 30 minutes after control of blood pressure, (4) 1.5 hours after control of blood pressure, (5) 3.5 hours after control of blood pressure, and (6) 30 minutes after discontinuing nifedipine. Coronary sinus and great cardiac vein blood flows were measured by the continuous thermodilution technique using the Baim coronary sinus flow catheter. Intravenous nifedipine was run initially at an average rate of 1.82 microg/kg/min. It took an average time of 12 minutes to lower the blood pressure to less than 130 mmHg systolic. There were highly significant decreases in systolic, mean, and diastolic blood pressures (P < .001), associated with significant decreases in systemic vascular resistance (P < .001) and left ventricular stroke work index (P < .05). There was an increase in cardiac output at 30 and 90 minutes of infusion (P < .05), and the stroke volume was increased 90 minutes after starting nifedipine (P < .05). The increase in heart rate was not significant. There was no significant effect on conduction times as measured by PR and QRS intervals on the ECG. However, the QTc interval was decreased after 3.5 hours (P < .05). There was an increase in right atrial pressure at 90 minutes and again 30 minutes after stopping nifedipine. (P < .05). The pulmonary artery pressure also was increased after stopping the infusion (P < .05). The pulmonary capillary wedge pressure, pulmonary vascular resistance, and right ventricular stroke work index remained unchanged. Coronary sinus and great cardiac vein flows were maintained despite a decrease in perfusion pressure, suggesting that nifedipine is a potent coronary vasodilator. Indeed, coronary vascular resistance was significantly decreased (P < .05). Myocardial oxygen consumption remained unchanged. The lactate extraction indicated that myocardial metabolism remained aerobic regionally and globally. Thus, the results suggest that blood pressure was easy to control and that there were no adverse effects on atrioventricular conduction, cardiac performance, regional and global myocardial oxygen utilization, or lactate extraction.

Adult↗
PubMed1988

Antagonism of neuromuscular blockade. The cardiovascular effects in children of the combination of edrophonium and glycopyrronium.

Glycopyrronium 5 or 10 micrograms/kg was administered either simultaneously with, or 1 minute before, edrophonium 1 mg/kg in order to antagonise competitive neuromuscular blockade in 80 children. Both doses of glycopyrronium given before the edrophonium resulted in an initial significant (p less than 0.01) increase in heart rate. Heart rate decreased significantly (p less than 0.01) in all groups after the edrophonium was given, and only glycopyrronium 10 micrograms/kg administered before edrophonium prevented a substantial decrease below baseline. Initial heart rate responses to glycopyrronium or edrophonium are rapid, and measurements at intervals of 30 seconds may be necessary to record these changes.

Child↗
PubMed1988

Method for showing human spermatogenesis using Arachis hypogaea (AHA) lectin.

Using biotinylated Arachis hypogaea agglutinin (AHA) or peanut lectin (PNA) and an avidin-peroxidase procedure, the various stages of spermatid development were visualised with great clarity; a light haematoxylin counterstain permitted the easy recognition of spermatogenic cells in the same section. This method is particularly useful in the interpretation of poorly fixed material and may be helpful in studies of cyclical maturation of spermatozoa, irrespective of whether the material is obtained at biopsy or necropsy.

Acrosome↗
PubMed1988

Different physiological signatures of sweat gland secretory and duct cells in culture.

Human eccrine sweat gland cells grown in culture were found to lose their characteristic shape, becoming flattened and organized into multilayers. The resting membrane potentials of the cultured secretory cells (-35 +/- 2 mV, n = 36) were significantly higher than those measured for cultured duct cells (-22 +/- 1 mV, n = 58, P less than or equal to 0.01). When the cholinergic agonist methacholine (10(-5) or 10(-6) M) was administered, the cultured secretory cells could be distinguished unequivocally by their atropine-sensitive hyperpolarizing response (-20 +/- 2 mV, n = 43), whereas no cultured duct cells responded. When the sodium conductance antagonist amiloride (10(-5) or 10(-6) M) was administered, 44% of cultured secretory cells responded by hyperpolarization (-8 +/- 1 mV, n = 8), whereas 87% of cultured duct cells hyperpolarized (-15 +/- 1 mV, n = 46) and by a significantly greater margin (P less than or equal to 0.01). Substitution of chloride with gluconate in the bathing medium caused membrane potential depolarization in both cultured secretory and duct cell populations, which is consistent with the presence of a chloride conductance in the plasma membrane. The beta-adrenoceptor agonist isoproterenol induced a transient hyperpolarization of 5-10 mV in three out of six cultured secretory cells tested but had no effect on cultured duct cells.

Atropine↗
PubMed1987

Elimination of the non-specific binding of avidin to tissue sections.

A simple procedure is described for eliminating non-specific staining with avidin-peroxidase conjugates. Murine ovaries were embedded in either paraffin wax or epoxy resin and, after blocking endogenous peroxidase activity, were treated with 10 micrograms/ml biotinylated Pisum sativum agglutinin. Avidin-peroxidase conjugates (5 micrograms/ml), diluted in standard 0.05 M tris-buffered saline, pH 7.6, containing 0.139 M NaCl, produced considerable background coloration and intense mast cell staining in controls without the lectin. This background diminished as the ionic strength of the buffer was raised. At 0.125 M Tris-buffered saline (containing 0.347 M NaCl) the background was completely unstained, with elimination of all binding to mast cells and only minimal loss of specific lectin binding.

Avidin↗
PubMed1987

Proteolysis and lectin histochemistry.

Lectin binding to formalin-fixed, paraffin-embedded tissue can often be enhanced by pre-treatment of the sections with proteolytic enzymes. However, the pattern of staining may be profoundly influenced by the type of enzyme preparation which is used. Sites of binding of thirteen different lectins to murine ovary and thyroid gland were studied after exposure of tissue sections to crude trypsin, purified trypsin, purified alpha-chymotrypsin, pepsin, protease VII, papain, bromelain, thermolysin or elastase. With most lectins, the results obtained were similar regardless of which enzyme was used for proteolytic digestion. However, the pattern of binding of soy bean lectin to the ovary and of concanavalin A and common pea lectin to the thyroid gland was highly dependent upon the enzyme used to pre-treat the sections. In both tissues, the staining pattern seen in untreated frozen sections was similar to that found in formalin-fixed, paraffin-embedded material digested with purified trypsin, but was different from that observed after exposure of processed sections to crude trypsin. The location of binding sites after treatment of paraffin sections with chymotrypsin was the same as that after digestion with crude trypsin. Results obtained after the use of other proteolytic enzymes varied according to the tissue being studied. These findings imply that the effect of treatment with crude trypsin is due to contaminating chymotrypsin, and demonstrate that the use of purified trypsin may have advantages over other proteolytic enzymes in lectin histochemistry. The observations may also apply to other related cytochemical techniques such as immunocytochemistry.

Animals↗
PubMed1987

Glycopyrrolate intensifies neuromuscular blockade produced by atracurium in the rat diaphragm preparation.

The effect of glycopyrrolate (Glycopyrronium, a muscarinic antagonist) (10 mumol.litre-1) and neostigmine (1 mumol.litre-1) on atracurium (0.1-100 mumol.litre-1) - induced neuromuscular blockade was studied in the rat isolated phrenic nerve-diaphragm preparation, to see if glycopyrrolate intensified the neuromuscular blockade produced by atracurium in this preparation. Atracurium had a rapid onset of blockade, reaching a complete block in 30-40 s. Glycopyrrolate had no significant effect on indirectly-elicited twitch (0.2 Hz) tension, whereas it significantly increased atracurium-induced depression of twitch tension and shortened the time needed to a complete block by 10 s. Combinations of glycopyrrolate+ neostigmine, only slightly reversed atracurium-induced blockade, if compared to the reversal by neostigmine alone. The mean concentrations to produce 50% depression of twitch tension were: 1.6 +/- 0.1 (atracurium), 0.3 +/- 0.1 (atracurium +glycopyrrolate), 4.8 +/- 0.2 (atracurium +neostigmine) and 2.7 +/- 0.1 mumol.litre-1 (atracurium +glycopyrrolate +neostigmine) (means +/- SEM, n = 6, P less than 0.001, with respect to control value of atracurium alone). It was concluded that glycopyrrolate enhanced atracurium-induced neuromuscular blockade in the rat diaphragm preparation, and that this effect should be noted when dosing glycopyrrolate in man.

Animals↗