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Biomedical subjects

R J Jones

Publications and source records attributed to R J Jones.

At least 163 records · Page 9Linked to original sources
PubMed1986

Characterisation of mouse monoclonal antibodies produced by immunisation with a single serotype component of a polyvalent Pseudomonas aeruginosa vaccine.

Mouse monoclonal antibodies raised by immunisation with a protective antigen extract from Pseudomonas aeruginosa serotype 1 varied in immunoglobulin isotype, in passive protective properties against infection by homologous P. aeruginosa serotype 1, and in cross-reactions in ELISA against antigen preparations from 15 other P. aeruginosa serotypes. All monoclonal antibodies with specificity in ELISA for the immunising antigen gave some degree of protection to mice against lethal infection by the homologous P. aeruginosa serotype. The IgG antibodies were more protective than the IgM antibodies.

Animals↗
PubMed1986

Kernel abortion in maize : I. Carbohydrate concentration patterns and Acid invertase activity of maize kernels induced to abort in vitro.

Kernels cultured in vitro were induced to abort by high temperature (35 degrees C) and by culturing six kernels/cob piece. Aborting kernels failed to enter a linear phase of dry mass accumulation and had a final mass that was less than 6% of nonaborting field-grown kernels. Kernels induced to abort by high temperature failed to synthesize starch in the endosperm and had elevated sucrose concentrations and low fructose and glucose concentrations in the pedicel during early growth compared to nonaborting kernels. Kernels induced to abort by high temperature also had much lower pedicel soluble acid invertase activities than did nonaborting kernels. These results suggest that high temperature during the lag phase of kernel growth may impair the process of sucrose unloading in the pedicel by indirectly inhibiting soluble acid invertase activity and prevent starch synthesis in the endosperm. Kernels induced to abort by culturing six kernels/cob piece had reduced pedicel fructose, glucose, and sucrose concentrations compared to kernels from field-grown ears. These aborting kernels also had a lower pedicel soluble acid invertase activity compared to nonaborting kernels from the same cob piece and from field-grown ears. The low invertase activity in pedicel tissue of the aborting kernels was probably caused by a lack of substrate (sucrose) for the invertase to cleave due to the intense competition for available assimilates. In contrast to kernels cultured at 35 degrees C, aborting kernels from cob pieces containing all six kernels accumulated starch in a linear fashion. These results indicate that kernels cultured six/cob piece abort because of an inadequate supply of sugar and are similar to apical kernels from field-grown ears that often abort prior to the onset of linear growth.

Journal Article↗
PubMed1986

Kernel Abortion in Maize : II. Distribution of C among Kernel Carbohydrates.

This study was designed to compare the uptake and distribution of (14)C among fructose, glucose, sucrose, and starch in the cob, pedicel, and endosperm tissues of maize (Zea mays L.) kernels induced to abort by high temperature with those that develop normally. Kernels cultured in vitro at 30 and 35 degrees C were transferred to [(14)C]sucrose media 10 days after pollination. Kernels cultured at 35 degrees C aborted prior to the onset of linear dry matter accumulation. Significant uptake into the cob, pedicel, and endosperm of radioactivity associated with the soluble and starch fractions of the tissues was detected after 24 hours in culture on labeled media. After 8 days in culture on [(14)C]sucrose media, 48 and 40% of the radioactivity associated with the cob carbohydrates was found in the reducing sugars at 30 and 35 degrees C, respectively. This indicates that some of the sucrose taken up by the cob tissue was cleaved to fructose and glucose in the cob. Of the total carbohydrates, a higher percentage of label was associated with sucrose and a lower percentage with fructose and glucose in pedicel tissue of kernels cultured at 35 degrees C compared to kernels cultured at 30 degrees C. These results indicate that sucrose was not cleaved to fructose and glucose as rapidly during the unloading process in the pedicel of kernels induced to abort by high temperature. Kernels cultured at 35 degrees C had a much lower proportion of label associated with endosperm starch (29%) than did kernels cultured at 30 degrees C (89%). Kernels cultured at 35 degrees C had a correspondingly higher proportion of (14)C in endosperm fructose, glucose, and sucrose. These results indicate that starch synthesis in the endosperm is strongly inhibited in kernels induced to abort by high temperature even though there is an adequate supply of sugar.

Journal Article↗
PubMed1986

Successful transfer of DHP-degrading bacteria from Hawaiian goats to Australian ruminants to overcome the toxicity of Leucaena.

Cattle and goats in Australia lack the ability to totally degrade 3-hydroxy-4(1H)-pyridone, also known as 3,4-dihydroxy pyridine (3,4 DHP), the ruminal metabolite of mimosine, a toxic aminoacid present in the leguminous shrub Leucaena leucocephala. Ruminants in Hawaii have this capacity due to the presence of micro-organisms able to rapidly degrade the DHP. A mixed bacterial population capable of rapidly degrading DHP in vitro was isolated from a goat on the island of Maui. Cultures were grown anaerobically, without added sugars, in Medium 98-5 containing DHP. Cultures at a dilution of 10(-12) from the original rumen fluid were introduced into Townsville and further sub-cultured and multiplied in vitro in strict isolation at the Oonoonba Veterinary Laboratory, Townsville. Infusion of the culture into a goat and a steer fed a 100% leucaena diet resulted in cessation of DHP excretion in the urine. After 60 days the serum thyroxine levels and thyroid size were normal and there were no clinical signs of disease. The ability of the rumen fluid to degrade DHP in vitro showed that the bacteria had become established in the rumen. In the absence of any disease in the animals, clearance has been given for the wider use of these cultures in areas where leucaena is grown. The limited evidence suggests that the leucaena toxicity problem can be solved by the use of these introduced bacteria.

Animals↗
PubMed1986

Passive immunization of mice against Klebsiella aerogenes.

Klebsiella vaccines were isolated by mild diafiltration techniques from culture filtrates of nine capsular types of K. aerogenes (K1, K2, K3, K15, K20, K35, K36, K44 & K63). The bacteria were grown in a chemically defined medium in standardized conditions in a fermenter. The vaccines had a molecular weight of more than 20 000, a carbohydrate content of 40-89%, a protein content of between less than 1 and 16% and small amounts (0.6-1.2%) of lipopolysaccharide. Antisera raised in rabbits to the nine klebsiella vaccines were standardized by passive haemagglutination, immunoglobulin G enzyme-linked immunosorbent assay and by autologous passive protection tests. Each rabbit antiserum when passively transferred to mice showed a variable capacity to passively protect mice against lethal infections by a panel of ten capsular types of K. aerogenes (K1-K10). Seven of the rabbit antisera protected mice against more than half of the challenge strains. A pool of six rabbit antisera (anti-K1, K2, K3, K20, K35 & K44) passively protected mice against lethal infections from strains of bacteria representing each of 77 capsular types of K. aerogenes.

Animals↗
PubMed1985

Enzyme-linked immunosorbent assay (ELISA) and a passive haemagglutination test (PHT) for the detection of pseudomonas antibodies in burned patients.

Pseudomonas antibodies were measured in serial plasma samples from patients with burns using an enzyme-linked immunosorbent assay (ELISA), passive haemagglutination test (PHT) and a passive protection test (PPT). ELISA and PHT showed that from 7 days after burning, 15 patients immunized with a 16-part polyvalent vaccine had higher titres of antibody to the 16 antigens in the vaccine than 15 unvaccinated patients. There was evidence that ELISA and PHT detected different pseudomonas antibodies in the plasma samples. When a single antigen (type 6) from the polyvalent vaccine was used in ELISA it failed to monitor antibodies in the plasma from vaccinated and unvaccinated burned patients shown by a PPT to protect mice against Pseudomonas aeruginosa serotype 6. PHT gave a closer correlation of protective antibodies against type 6 antigen than ELISA.

Animals↗
PubMed1985

Measurement of platelet aggregation in diabetics using the new electronic platelet aggregometer.

Platelet function has been studied in diabetic subjects using a new electronic platelet aggregometer which enables platelet aggregation to be studied in whole blood. This may be a more physiological approach to the assessment of platelet behaviour as centrifugation is avoided and platelets are studied in the presence of other blood elements which may be important modulators of platelet function in vivo. Twenty insulin-dependent diabetic subjects were studied along with 20 age and sex-matched controls. Platelet aggregation to collagen (1 microgram/ml) and arachidonic acid (1 mM) was significantly increased in the diabetic group. In addition the sensitivity of diabetic platelets to the antiaggregatory effects of prostacyclin was significantly reduced. A significant inverse correlation was found between platelet sensitivity to prostacyclin and glycosylated haemoglobin concentration in the diabetic group. It is unlikely that the platelet abnormalities in this diabetic group are due to underlying vascular disease as none of the patients had evidence of diabetic complications. These findings may have important implications for the development of vascular disease in diabetics.

Adult↗
PubMed1984

Australian goats detoxify the goitrogen 3-hydroxy-4(1H) pyridone (DHP) after rumen infusion from an Indonesian goat.

The failure of Australian goats fed Leucaena leucocephala (leucaena) to degrade 3-hydroxy-4(1H) pyridone (DHP), the goitrogenic metabolite of mimosine, was overcome when they were infused with rumen fluid from an Indonesian goat. The leucaena toxicity problem in Australia may well be solved by transfer of specific bacteria capable of degrading DHP anaerobically.

Animal Feed↗
PubMed1984

Vaccination against Klebsiella aerogenes.

Klebsiella vaccine was prepared from strains of Klebsiella aerogenes with capsular types K1, K36, K44 and K Cross (a type which cross-reacts in vitro with sera from many klebsiella capsular types). The vaccine was extracted by dialysis and ultrafiltration from capsular material released during growth of the bacteria in a five-day batch culture. Mice given one dose of vaccine from K1a (1.0 microgram/mouse) survived lethal intraperitoneal challenge of 11/11 homologous klebsiella strains four days after vaccination; 14 days after vaccination protection against the same challenge strains had declined to 5/11 strains. Vaccines from K1a, b, c, K36, K44 and K Cross induced homologous protection and protected mice against different ranges of heterologous klebsiella capsular types. The protective response of the mice was greatly enhanced by administering three doses of the vaccines. Vaccines from K1, K36, K44 and K Cross protected mice against 14/20, 11/20, 10/20 and 9/20 homologous and heterologous klebsiella challenge strains respectively. None of the klebsiella vaccines was toxic for mice at the immunizing dose (1.0 microgram/mouse). Vaccine from K36 was the most lethal, killing mice at 10(3) immunizing doses. The least toxic vaccine was from K44, which killed mice at 10(4) immunizing doses.

Animals↗
PubMed1984

Vaccination against 77 capsular types of Klebsiella aerogenes with polyvalent Klebsiella vaccines.

A method is described for producing monovalent and polyvalent vaccines from culture filtrates of Klebsiella aerogenes. With a single injection, each monovalent vaccine protected mice against lethal intraperitoneal challenge by more than 30 capsular types; and polyvalent vaccines containing 2-12 monovalent components protected against 46-61 of the 77 capsular types of K. aerogenes. One vaccine with 12 components, administered in two doses, induced full protection against 71 types and protected half of the mice challenged with the other six types.

Animals↗
PubMed1983

Identifying determinants of risk of sexual victimization of youth: a multivariate approach.

The present study argues that a greater understanding of the factors which contribute to a youth's sexual victimization is likely to not only be based on what we know about the youths who are victimized but also on comparative information on youths who are not. Selected social background variables from a sample of young victims (n = 20) and nonvictims (n = 21) representing a population of youths with histories of antisocial behavior were compared. Using stepwise discriminant analysis several factors relating to youths' home environment significantly discriminated victims from nonvictims. The results suggest that the probability of being sexually victimized is increased when the home environment is unstable and lacks adequate control over youths' activities. The need for improved research methodologies to achieve better identification of determinants of risk is discussed. Multivariate assessment of social, situational, and personal factors of victims and nonvictims is recommended as a potentially promising approach for improving current rape prevention efforts.

Adolescent↗
PubMed1983

Active and passive immunization against Pseudomonas aeruginosa infection of burned patients.

A 16-part polyvalent pseudomonas vaccine, PEV-01 and an immunoglobulin prepared from plasma from human volunteers vaccinated with PEV-01 were tested in a controlled clinical trial in burned patients at Safdarjang hospital, New Delhi. The mortality of the burned patients was reduced four-fold in adults and three-fold in children by the immunological treatments. Both immunoglobulin and vaccine increased the concentration of protective antibody. Patients responded to all 16 components in PEV-01. The vaccine caused no toxic side-effects and enhanced the bactericidal activity of polymorphonuclear leucocytes against Pseudomonas aeruginosa.

Adult↗
PubMed1983

The role of the O and K antigens in determining the resistance of Klebsiella aerogenes to serum killing and phagocytosis.

The presence of both K and O antigens of Klebsiella aerogenes was found necessary to protect the organism from either complement-mediated serum killing or phagocytosis in the absence of specific antisera. Optimal phagocytic ingestion of K. aerogenes NCTC 5055 could be achieved in the presence of either anti-K or anti-O sera or to a much smaller extent in antisera raised against a rough unencapsulated mutant (M10B) derived from NCTC 5055. Anti-O sera failed to opsonize a clinical klebsiella isolate (DL1) possessing immunologically identical lipopolysaccharide, but did so when the amount of capsule was physically reduced. The serum sensitivity of the encapsulated strains was unaffected by the addition of specific antisera. Fresh serum was bacteriostatic for an unencapsulated smooth mutant (M10) derived from NCTC 5055. This bacteriostatic effect was reduced by heat-inactivation of the serum or by the addition of anti-O serum. M10 was rendered sensitive to the bactericidal action of serum in the presence of antisera raised against M10B or after chelation with MgEGTA to isolate alternative complement pathway activity. The rough unencapsulated mutant (M10B) was rapidly killed by fresh serum, an effect which could be delayed by chelation with MgEGTA. The serum sensitivity of M10B was unaffected by the presence of anti-M10B sera. Thus, the O antigen, unlike the K antigen, of these klebsiella strains is not antiphagocytic but it does confer some protection against the rapid bactericidal activity of serum complement.

Antigens↗
PubMed1983

The effect of histamine H2 receptor antagonists on platelet aggregation in man.

The in vivo and in vitro effects on the aggregatory response of human platelets to ADP and collagen of a series of imidazole and non-imidazole histamine H2 receptor antagonists, and imidazole derivatives, have been studied. Bolus i.v. administration of the antagonists cimetidine and oxmetidine was without effect. However, inhibition of platelet aggregation was observed in vitro with oxmetidine, metiamide and to a lesser extent burimamide, but not with cimetidine or the non-imidazole antagonist ranitidine. Of the imidazole derivatives only imidazole and its 1-methyl analogue significantly affected platelet aggregation. The relationship between potency as a histamine H2 receptor antagonist, the presence of an imidazole ring structure and the antiaggregatory effectiveness of these compounds is discussed. Although certain antagonists clearly inhibit platelet aggregation in vitro, effects are only seen at drug concentrations exceeding those achieved under normal therapeutic conditions; thus the clinical significance of these observations remains to be determined.

Burimamide↗