Cell biology. Devious devices of Salmonella.
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Animals↗
Biomedical subjects
G A Smith
Publications and source records attributed to G A Smith.
Cloning and characterization of a gene encoding extracellular metalloprotease from Streptomyces lividans.
The prt gene, encoding a protease (Prt) from Streptomyces lividans TK24, was cloned and sequenced. An S. lividans host with plasmid-borne prt secreted 200 micrograms/ml of a 22-kDa Prt into the culture medium. Prt is classified as a metalloprotease since its activity is significantly inhibited by 1,10-phenanthroline or EDTA. The region upstream from prt codes for an incomplete open reading frame (ORF) oriented opposite to prt. This ORF has a strong similarity to a gene family (lysR) whose members regulate the transcription of structural genes required for either biosynthesis or degradation.
Amino Acid Sequence↗
The effect of clinical use and sterilization on selected orthodontic arch wires.
The effect of clinical use and various sterilization/disinfection protocols on three types of nickel-titanium, and one type each of beta-titanium and stainless steel arch wire was evaluated. The sterilization/disinfection procedures included disinfection alone or in concert with steam autoclave, dry heat, or cold solution sterilization. No clinically significant differences were found between new and used arch wires. The direction of load application to the arch wire and the particular segment of arch wire tested was found to cause substantial differences in generated loads for certain arch wire types.
Analysis of Variance↗
An allometric-autoregressive approach to poultry development.
1. The relative rates of development in a commercial layer and a broiler strain of chicken fed 180 or 230 g crude protein/kg were investigated by the use of the allometric-autoregressive model. Development was divided into pre-pubertal (0 to 8 weeks) and pubertal phases (8 to 22 weeks). 2. Significant strain effects were observed, at all ages, in rates of gain of live (L) body mass, carcass (C) mass, non-carcase (N) mass and empty-body (EB) mass as well as C, N and EB moisture, protein and fat content. 3. Significant dietary effects were observed in C and EB fat in the pre-pubertal phase and L mass, N protein and C fat in the subsequent pubertal period.
Adipose Tissue↗
Platelet counting using plasma platelet concentrate samples.
Platelet counting using samples of plasma from platelet concentrates prepared for transfusion was assessed. The methods employed included a manual phase-contrast method, and counting with Coulter S Plus and Sysmex E-2500 counters. All methods were reproducible (mean CV of 4.9, 2.2 and 1.4%, respectively). However, neat samples of platelet concentrates analysed by Coulter counter were inaccurate (mean count of 863.8 x 10(9)/l compared to 1018.9 x 10(9)/l counted manually). Moreover, the Coulter platelet counts were non-linear above 900 x 10(9)/l, whereas the E-2500 platelet counts were linear to 2700 x 10(9)/l. A one-in-three pre-dilution was required to obtain accurate, linear counts with the Coulter counter, whereas the E-2500 was accurate without pre-dilution (mean count of 1030.2 x 10(9)/l compared to 1018.9 x 10(9)/l counted manually). In conclusion, the method of platelet counting may affect true platelet yields.
Automation↗
A light microscopical study of the intestinal tract of the Nile crocodile (Crocodylus niloticus, Laurenti 1768).
Although the histology of the intestinal tract of Crocodylus niloticus is touched on in overall studies on reptilian intestinal tract, a more comprehensive light microscopical study on this area is lacking. Specimens for histological examination were taken from the duodenum, the jejunum, the ileum and the rectum. The data obtained revealed that the mucosa is thrown into folds and simple, slightly branched tubular intestinal glands. The mucosal folds diminished in height and eventually disappeared upon reaching the ileorectal junction. The epithelium covering the folds and crypts was of the simple columnar type. Clear marginal cells, goblet cells and argentaffin cells were observed throughout the intestinal tract. No Paneth cells were seen in this study. The lamina propria was rich in lymphocytic infiltrations while the muscularis mucosa consisted mainly of an outer longitudinal layer, the inner circular layer being rudimentary or absent. The submucosa was extremely narrow, and the circular and longitudinal layers of the tunica muscularis contained distinct layers of dense fibrous connective tissue. The histology of the intestinal tract of C. niloticus is shown to be in line with the situation in crocodilians and also exhibits a resemblance to that of carnivorous mammals.
Alligators and Crocodiles↗
Biomechanical analysis of cross-country skiing techniques.
The development of new techniques for cross-country skiing based on skating movements has stimulated biomechanical research aimed at understanding the various movement patterns, the forces driving the motions, and the mechanical factors affecting performance. Research methods have evolved from two-dimensional kinematic descriptions of classic ski techniques to three-dimensional analyses involving measurement of the forces and energy relations of skating. While numerous skiing projects have been completed, most have focused on either the diagonal stride or the V1 skating technique on uphill terrain. Current understanding of skiing mechanics is not sufficiently complete to adequately assess and optimize an individual skier's technique.
Biomechanical Phenomena↗
Bioactive peptides and serotonin in the gut endocrine cells of the crocodile, Crocodylus niloticus (Laurenti 1768): an immunocytochemical study.
Little is known about peptide-storing endocrine cells in the gut of the Nile crocodile. As in the case of other reptiles, particularly the alligator, a limited range of peptide-storing cells was found in the gut of the crocodile. They were somatostatin, glucagon, gastrin, neurotensin and pancreatic polypeptide. The topographical distribution of cells immunoreactive to somatostatin and gastrin in the gut of the crocodile is comparable to the situation in the alligator. Glucagon and neurotensin immunoreactive cells have a much wider distribution in the gastro-intestinal tract of the crocodile compared to the alligator. Cholecystokinin and bombesin cells previously reported in the small intestine of the alligator were not detected in this study. This is the first report to demonstrate pancreatic polypeptide and serotonin immunoreactivity in the gut of a crocodilian specie.
Alligators and Crocodiles↗
Influence of phased inclusion of halofuginone on broiler skin tensile strength and growth performance.
The effect of continuous administration, weekly 24 h administration, phased withdrawal and phased inclusion of dietary halofuginone at 3 mg kg-1 on skin tensile strength was tested in Ross I broiler pullets. Controls received monensin continuously at 100 mg kg-1. A total of 2,592 birds were used in 2 lots of 1,296 in 2 separate programmes. Continuous dietary administration of halofuginone affected skin tensile strength negatively (P less than 0.05), with an equally significant recovery following a 7 d withdrawal period. A polynomial regression analysis indicates that skin strength may undergo a slight compensatory overstrengthening reaction within 7 d of withdrawal of halofuginone. Weekly 24 h administration of halofuginone reduced differences in skin strength between treatment and controls to non-significant levels. Differences in skin strengths between controls and the halofuginone phased inclusion programme decreased as the birds aged, being significant (P less than 0.05) on Days 14 and 28 and non-significant on Days 21, 35, 42 and 49. A weakening of skin tensile strength of broiler carcasses, as far as it may be influenced by halofuginone, can be alleviated through different shuttle programmes involving halofuginone. Such programmes would include intermittent dosing, a withdrawal period, administration to older birds or a combination of these programmes.
Animals↗
Influence of continuous dietary halofuginone on broiler skin tensile strength and growth performance.
Halofuginone was administered to both sexes of 2 broiler strains, Ross and Hubbard, in 4 dietary treatments, 0, 1.5, 3 and 6mg kg-1. Controls received dietary monensin at 100 mg kg-1. Group feed intake and body mass were recorded weekly. Skin tensile strength was monitored on Days 28, 35, 42 and 49 using a standardised cut of breast skin from carcasses randomly drawn from each treatment, strain and sex combination. Halofuginone inclusion level was inversely correlated (r = -0.36) with skin tensile strength and affected both sexes of the 2 strains (P less than 0.01). Between sexes, the skins of cockerels were consistently stronger than those of hens (P less than 0.01). The effect of age (P less than 0.07) and that of strain (P less than 0.06) tended towards significance at the 5% level. The singular effect of halofuginone on skin tensile strength was masked by the interactions treatment and sex (P less than 0.01); treatment and age (P less than 0.02); treatment and strain (P less than 0.06); age and strain (P less than 0.01). An inclusion level of 6mg kg-1, double the recommended level, could reduce growth and skin tensile strength significantly.
Animals↗
The origin of multiply sigmoid curves of pH-dependence. The partitioning of groups among titration pK values.
An acid, HnA, with n ionizing groups is known to have the same titration curve as an equimolar mixture of n hypothetical monobasic acids, whose dissociation constants are known as the 'titration constants' of the real acid. We show that the pH-dependence of any property of HnA is also represented by the sum of one-site titration curves, characterized by these same titration constants. Since one such property is the degree of dissociation of one of the dissociating groups, a fraction of each group shows each of the various titration pK values, so that the group partitions among them. The n groups therefore share the same n titration pK values but differ in the fractions belonging to each. The one H+ ion per molecule that titrates with each pK is thus made up of the fractions, one from each group, that share this pK value. A group may possess a single pK value, in that it contributes virtually all of this pK and almost nothing to the others, only if either (1) in titrates in a different pH range from the other groups or (2) its affinity for H+ is unaffected by their ionization state.
Acids↗
An acetylation method for the quantification of membrane lipids, including phospholipids, polyphosphoinositides and cholesterol.
A method for the quantification of membrane lipids by acetylation with [3H]acetic anhydride is described. A standard lipid, labelled with 14C or 32P, is added to the sample and is simultaneously acetylated. The 3H/14C or 3H/32P ratios obtained in the acetylated lipids are proportional to the initial lipid concentration. The method has been used to quantify cholesterol, phosphatidylethanolamine, phosphatidylinositol, sphingomyelin, phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate in amounts between 2 and 10 nmol.
Acetylation↗
Nucleotide and amino acid sequence analysis of the thymidine kinase gene of a bovine encephalitis herpesvirus.
The nucleotide and predicted amino acid sequence of the thymidine kinase (TK) gene of N 569, a bovine encephalitis herpesvirus (BEHV), has been determined and compared with those of avian, bovine and other mammalian herpesvirus TK genes. Striking differences were observed between the nucleotide sequence of this BEHV TK gene and those reported for bovine herpesvirus 1 (BHV-1). A total of 118 base changes, 39 base deletions and 14 base insertions were identified relative to the TK sequence of a BHV-1.2a strain, resulting in a net loss of seven residues. Comparison of the TK sequences of BEHV and the BHV-1 Q 3932 strain with that reported for the BHV-1 6660 strain suggested that the latter may have contained sequencing errors. The most significant difference between the BEHV TK sequence and those of BHV-1 strains was the absence of a contiguous stretch of ten codons.
Amino Acid Sequence↗
Performance of occlusin in butt-joint and bevel-edged preparations: five-year results. 4.
The five-year findings of a study to compare the performance of restorations of Occlusin (ICI Dental, Macclesfield, UK) in butt-joint and bevel-edged preparations are reported. Ninety-four (79%) of the restorations originally placed were reviewed at five years, 20 restorations (17%) having failed during the study. Initial analysis of the overall results having failed to reveal any significant differences between the five-year performance of the two types of restorations, the results were combined and analyzed by Chi-square tests and step-wise logistic regression. Chi-square analysis indicated that of the independent variables investigated, size of restoration had the greatest effect on clinical performance. Step-wise logistic regression revealed that only four of the eight dependent variables investigated showed significant predictive relationships with the independent variables, the logistic equation for occlusal marginal adaptation being the most complex. The greatest amount of generalized occlusal surface wear tended to be seen in large-sized Class II restorations in molar teeth, with the main factor influencing wear being found to be the type of restoration (Class I or Class II). It is concluded that the performance of restorations of Occlusin has not been found to differ significantly in butt-joint and bevel-edged preparations after five years in clinical service. Step-wise logistic regression has been found to be a useful tool in the analysis of data obtained during the clinical evaluation of a restorative material.
Adolescent↗
Continuous intravenous infusion fentanyl for sedation and analgesia of the multiple trauma patient.
Fentanyl is an attractive agent for analgesia in the emergency department. Its use in this setting has been limited to IV bolus administration. We report successful sedation, muscle relaxation, and analgesia of a multiple trauma patient with fentanyl IV bolus and continuous infusion in the ED.
Adult↗
Identification by immunoblotting of the erythrocyte membrane sialoglycoproteins that carry the Vw and Mur antigens.
Immunoblotting of the separated membrane components of MiI erythrocytes with anti-Vw identified a band of Mr 40,000 with a mobility close to that of beta-sialoglycoprotein corresponding to the abnormal alpha-sialoglycoprotein present in MiI cells. A comparison of results obtained when MiIII erythrocytes were immunoblotted with anti-Mur, anti-s and the monoclonal antibody R1.3, indicated that the Mur antigen is located on the abnormal delta-sialoglycoprotein of Mr 36,000 in MiIII erythrocytes. Prior treatment of MiI erythrocytes with neuraminidase resulted in an increase in the intensity of staining of the anti-Vw reactive component. This was consistent with the enhanced reactions observed in haemagglutination tests with neuraminidase-treated erythrocytes. The mobility of the Vw component was reduced when erythrocytes were pre-treated with low concentrations of neuraminidase but increased when higher concentrations of neuraminidase were used.
Erythrocyte Membrane↗
Analysis of the primary signals required for activation of the mitogenic pathway in murine thymocytes from protein phosphorylation patterns.
It has been proposed that phorbol esters and the Ca2+ ionophore A23187 are effective comitogens for some species of lymphocytes because together they mimic the normal secondary signals for cell activation by mitogens that cause phosphatidylinositol 4,5-bisphosphate (PtdInsP2) breakdown (e.g., anti-TCR and anti-Thy-1 antibodies and Con A). To test whether activation of protein kinase C and an increase in [Ca2+]i account for the activation of the mitogenic pathway in murine thymocytes by the mitogens that cause PtdInsP2 breakdown, the two-dimensional phosphorylation patterns generated by the three classes of mitogens (protein kinase C activator, Ca2+ ionophore, and activator of PtdInsP2 breakdown) and by activators of cAMP-dependent kinases have been compared. From the phosphorylation patterns, by which each mitogen could be distinguished reproducibly, it was concluded that: 1) The phosphorylation patterns generated by the mitogens that activate PtdInsP2 breakdown are only slightly affected by the removal of extracellular Ca2+ under conditions that abolish the normal rise in [Ca2+]i and do not therefore depend on the activation of Ca2(+)-dependent protein kinases. In contrast, the phosphorylation pattern generated by A23187 is totally dependent on extracellular Ca2+. 2) Neither A23187 nor the mitogens that activate PtdInsP2 breakdown nor activators of cAMP-dependent kinases caused significant activation of protein kinase C assayed by phosphorylation of the diagnostic proteins 80b and 78a. Consistent with this conclusion, only the phorbol esters or oleoyl acyl glycerol caused translocation of protein kinase C activity from the cytosolic to the membrane fraction. 3) Neither A23187 nor the mitogens that cause PtdInsP2 breakdown activated cAMP-dependent kinases. Taken together the data imply that the mitogens that cause PtdInsP2 breakdown must generate an additional, independent primary mitogenic signal. It is suggested that this signal may be the activation of tyrosine kinases (e.g., p56lck) via the TCR and working hypotheses for effective combinations of primary mitogenic signals that will activate DNA synthesis are developed.
Animals↗
Transdermal iontophoresis of gonadotropin releasing hormone (LHRH) and two analogues.
Gonadotropin releasing hormone (GnRH), as well as an antagonist [Ac-D2Nal,1 D4ClPhe,2 D3Pal,3 NicLys,5 DNicLys,6 ILys,8 DAla10] GnRH.HOAc (1) and a superagonist [DTrp6, Pro9-NHEt]GnRH (2), have been electrochemically driven across excised hairless mouse skin. Determined by HPLC analysis, the delivery rate from aqueous solution into isotonic saline at 0.5 mA cm-2 was as high as 19 nM cm-2 h-1 for 2. Because of its insolubility in water, analogue 1 could only be delivered from an acidic donor solution. Analogue 2 was also delivered in pulsatile fashion using current on/off cycles. For all three peptides, passive transport was negligible and stability is evident when in contact with the stratum corneum. Slow metabolism occurs when GnRH contacts the dermal side of hairless mouse skin.
Animals↗