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Biomedical subjects

J Prendergast

Publications and source records attributed to J Prendergast.

At least 19 recordsLinked to original sources
PubMed2005

Nitrification in a vertically moving biofilm system.

A laboratory continuous feed biofilm reactor, comprising a bulk fluid reactor, a biofilm plastic module, a feed tank, and pneumatic devices and controls, was operated for a total period of 257 days, including seeding time, to treat domestic-strength synthetic wastewater under increasing ammonium nitrogen (NH(4)(+)--N) loading rates, ranging from 0.17+/-0.01 (0.71+/-0.06 gm(-2)d(-1)) to 0.70+/-0.02 kgm(-3)d(-1) (2.9+/-0.1 gm(-2)d(-1)). The biofilm plastic module was moved vertically in and out of the wastewater in continuous cycles. The maximum NH(4)(+)-N removal rate was reached during the maximum loading phase, when a NH(4)(+)--N loading rate of 0.70+/-0.02 kgm(-3)d(-1) (2.9+/-0.1 gm(-2)d(-1)) was applied to the system. During this loading period, the average NH(4)(+)--N removal rate was 0.30+/-0.10 kgm(-3)d(-1) (1.30+/-0.40 gm(-2)d(-1)).

Ammonium Chloride↗
PubMed2005

The efficiency of a sequencing batch biofilm reactor in organic carbon and phosphorus removal.

A laboratory sequencing batch biofilm reactor (SBBR), operated for a period of 158 days, was used to treat domestic-strength synthetic effluent. The biofilm reactor comprised a bulk fluid reactor, a biofilm plastic module, a synthetic wastewater feed tank, and pneumatic devices with pneumatic controls. The reactor cycle time was 8 h, and its operation consisted of five phases: feeding (59 min), mixing (1 min), anoxic/anaerobic (3 h), aerobic (3 h), and settling (1 h). At total chemical oxygen demand (CODT) loading rates of 8.8 g CODT m(-2) d(-1) and 1.2 kg CODT m(-3) d(-1), expressed in terms of the plastic module surface area and reactor volume, respectively, the SBBR had average removal rates of 8.3 g CODT m(-2) d(-1) and 1.1 kg CODT m(-3) d(-1), or 94%. Total orthophosphorus (PO4-PT) and filtered orthophosphorus (PO4-PF) removals were 44% and 50%, respectively.

Biofilms↗
PubMed2003

A one-quarter reduction in the salt content of bread can be made without detection.

OBJECTIVE: To determine if it is possible to deliver a one-quarter reduction in the sodium content of bread without detection. DESIGN: Single-blind, randomized, controlled trial. SETTING: The Royal North Shore Hospital in Sydney, Australia. PARTICIPANTS: One-hundred and ten volunteers from the hospital staff that completed 94% of scheduled assessments. INTERVENTION: Six consecutive weeks of bread with usual sodium content or six consecutive weeks of bread with cumulating 5% reductions in sodium content each week. MAIN OUTCOME MEASURE: The proportion of participants reporting a difference in the salt content of the study bread from week to week. RESULTS: The intervention group were no more likely than the control group to report a difference in the salt content of the bread from week to week (P=0.8). Similarly, there were no differences between randomized groups in the scores for flavour (P=0.08) or liking of the bread (P=0.95) over the study follow-up period. However, the saltiness scores recorded on a visual analogue scale did decline in the intervention group compared with the control group (P=0.01) CONCLUSIONS: A one-quarter reduction in the sodium content of white bread can be delivered over a short time period, while maintaining consumer acceptance. Over the long term, and particularly if achieved for multiple foods, a decrease in sodium content of this magnitude would be expected to reduce population levels of blood pressure and the risks of stroke and heart attack.

Adult↗
PubMed2000

Comparison of flow rates of holes versus cross-cut teats for bottle-fed babies.

Under laboratory conditions the flow rates of two types of teat were compared. The openings of Group A teats were in the form of a cross-cut measuring 1.5 mm in radius plus a small central hole. Group B teats were pierced with a single hole of 0.5 mm in diameter. Five teats from each group were tested under atmospheric pressure conditions simulating the effect of a baby's sucking. The results of this trial confirms the hypothesis that the style of teat affects the flow rate and that faster flow rates can be obtained with a cross-cut teat rather than a single-hole teat. Babies using cross-cut teats may also learn to control flow rates by changing their sucking style.

Bottle Feeding↗
PubMed1999

Post-ictal psychosis: an unusual clinical entity.

OBJECTIVE: The aim of this paper is to describe a case of post-ictal psychosis (PIP) and to discuss the literature surrounding this interesting disorder. CLINICAL PICTURE: A 32-year-old woman with epilepsy presented on three occasions with psychosis following tonic-clonic seizures. TREATMENT AND OUTCOME: The psychosis resolved within 14 days on haloperidol 7 mg daily. CONCLUSIONS: Post-ictal psychosis is an unusual clinical entity that is frequently recurrent and may be misdiagnosed and treated inappropriately. Prophylaxis of PIP is an area for important future research.

Adult↗
PubMed1996

Effect of deoxycoformycin and Val-boroPro on the associated catalytic activities of lymphocyte CD26 and ecto-adenosine deaminase.

CD26 and ecto-adenosine deaminase (ADA) are found associated on the plasma membrane of T lymphocytes and each possess distinct catalytic activities. CD26 has a proteolytic activity identical to dipeptidylpeptidase IV (DPPIV; E.C. 3.4.14.5), and ecto-ADA (E.C. 3.5.4.4) degrades extracellular adenosine. The cell surface expression of CD26 and ecto-adenosine deaminase (ecto-ADA) is regulated on stimulated T lymphocytes, and ADA binding to CD26 produces a synergistic costimulatory response with T cell receptor activation. This study addresses the potential regulation by allosteric interactions of the catalytic activities of CD26 associated with ecto-ADA, which could define the mechanism of the synergism observed in T cell signaling. Cell lines genetically deficient in ADA, ligands for ADA such as adenosine, and a specific inhibitor of ADA, deoxycoformycin, were used to define the effect of ADA activity on CD26 DPPIV activity and affinity for dipeptide substrate. Conversely, a recombinant Chinese hamster ovary cell line expressing human CD26 with or without a mutation in the DPPIV catalytic domain, and the boronic acid inhibitor Val-boroPro, were used to determine the effect of DPPIV activity on ecto-ADA activity and association with CD26. These studies found no significant allosteric interaction between the catalytic activities of CD26 and ecto-ADA when associated. Therefore, signaling events in T cells involving costimulation with CD26 and ecto-ADA and the synergism observed upon ADA binding to CD26 occur independently of the catalytic activities of these cell surface molecules.

Adenosine Deaminase↗
PubMed1993

Human fetal liver gamma/delta T cells predominantly use unusual rearrangements of the T cell receptor delta and gamma loci expressed on both CD4+CD8- and CD4-CD8- gamma/delta T cells.

Substantial numbers of both alpha/beta and gamma/delta T cells are present in human fetal liver, which suggests a role of the fetal liver in T cell development. The diversity of fetal liver T cell receptor (TCR) gamma and delta chain rearrangements was examined among both CD4+CD8- and CD4-CD8- gamma/delta T cell clones. In addition, TCR delta chain transcripts from three fetal livers were sequenced after polymerase chain reaction amplification of TCR delta chains with V delta 1 or V delta 2 rearrangements. Five of six fetal liver gamma/delta T cell clones had a V delta 2-D delta 3-J delta 3 gene rearrangement with limited junctional diversity; three of these clones had an unusual CD4+CD8- phenotype. V delta 2-D delta 3-J delta 3 gene rearrangements were also common among both in-frame and out-of-frame transcripts from three fetal livers, indicating that they are the result of an ordered rearrangement process. TCR gamma chain sequences of the fetal liver gamma/delta T cell clones revealed V gamma 1-J gamma 2.3, V gamma 2-J gamma 1.2, and V gamma 3-J gamma 1.1 rearrangements with minimal incorporation of template-independent N region nucleotides. TCR gamma chain rearrangements found in these fetal liver T cell clones were different from those that have been observed among early thymic gamma/delta T cell populations, while similar TCR delta chain rearrangements are found among gamma/delta T cells from both sites. These data demonstrate that the fetal liver harbors gamma/delta T cell populations distinct from those found in the fetal thymus, suggesting that the fetal liver is a site of gamma/delta T cell development in humans. These unusual T cell populations may serve a specific function in the fetal immune system.

Amino Acid Sequence↗
PubMed1990

Binding of the T cell activation monoclonal antibody Ta1 to dipeptidyl peptidase IV.

The monoclonal antibodies, Ta1 and IOT15, define T cell activation cell surface markers and have been assigned to the CD26 leukocyte differentiation antigen cluster. Dipeptidyl peptidase IV (DPP IV, EC 3.4.14.5) is an exoaminopeptidase that, among leukocytes, is expressed almost exclusively on activated T cells. Comparative binding studies showed that the Ta1 mAb binds to DPP IV purified from human placenta as well as in extracts of the human YT lymphoid cell line and of CD3 stimulated normal human peripheral blood mononuclear cells. The mAb IOT15 did not bind to DPP IV from any source even upon repeated incubations. Western blot analysis of YT cell extracts revealed that Ta1 and IOT15 bound to distinctly different molecular weight molecules. Immunofluorescent cell surface capping experiments showed that capping of the IOT15 did not alter the surface distribution of the Ta1 fluorescence. The capping results combined with the DPP IV binding results indicate that IOT15 and Ta1 mAb's bind to different, apparently unassociated, molecules on the surface of T cells and that only Ta1 binds the T cell surface enzyme DPP IV.

Antibodies, Monoclonal↗
PubMed1990

Effects of exercise on serum amino-transferase activity and pyridoxal phosphate saturation in Thoroughbred racehorses.

Aminotransferase activities were measured in the serum of two- to three-year-old Thoroughbred fillies and colts during a four week period of peak training for flat racing. Aspartate aminotransferase (AspAT, EC 2.6.1.1), mitochondrial aspartate aminotransferase (m-AspAT) and alanine aminotransferase (AlaAT, EC 2.6.1.2) activities in serum were measured and the relative proportions of apoenzyme and holoenzyme were determined. The aminotransferase activities were increased only slightly immediately following exercise. This small and immediate post exercise increase in activity did not vary greatly over the period of peak training. Measured in the presence of exogenous pyridoxal 5'-phosphate, mean enzyme activities (iu/litre at 30 degrees C) before exercise were: AspAT, 291; m-AspAT, 13; AlaAT, 18. After exercise they were: AspAT, 317; m-AspAT, 16; AlaAT, 23. Nearly all of the AspAT activity was present in the holoenzyme form (94 per cent holoenzyme) indicating excellent vitamin B6 status in these animals. Paradoxically, the AlaAT in serum from the same highly trained Thoroughbred horses was poorly saturated with pyridoxal phosphate, with nearly half of the AlaAT in most horses present in the inactive apoenzyme form (61 per cent that of holoenzyme). It is critical therefore, that exogenous pyridoxal phosphate be included in aminotransferase assays to determine the amounts of enzyme release into the peripheral circulation.

Alanine Transaminase↗
PubMed1988

Characterisation of IgE-mediated histamine release from equine basophils in vitro.

In vitro IgE-mediated histamine release by equine blood basophils was characterised as the basis for a screening test for immediate hypersensitivity responses in horses. The responses are initiated by inducing agents that are capable of crosslinking or bridging the membrane-bound IgE molecules. The release process is complete within 40 mins. In vitro histamine release is dose-dependent, with a submaximal response at less or greater than the optimal dose of inducing agent. Exogenous calcium is required but not magnesium; the optimal release calcium concentration is 1.0 to 1.5 mM. If an IgE-mediated inducing agent is added in the absence of exogenous calcium, the basophils become desensitised. The pH and temperature optima for release are physiological (pH 7.4, 37 degrees C). Histamine release is potentiated by deuterium oxide.

Animals↗
PubMed1981

Diagnosis of parathyroid adenoma by computed tomography.

A diagnosis of cervical parathyroid adenoma was made at computed tomography (CT) in two patients not initially suspected of having primary hyperparathyroidism. In each case, the lesion appeared as an oval shaped mass indenting and deforming the posterior surface of one lobe of the thyroid gland. In one patient, the lesion was sharply contrasted by iodine-containing thyroid tissue, which appeared denser than the adenoma. The significance of these findings is discussed as well as some of the problems encountered in the CT diagnosis of parathyroid adenoma.

Adenoma↗
PubMed1979

A comparison of the effect of mid-thoracic spinal hemisection in the neonatal or weanling rat on the distribution and density of dorsal root axons in the lumbosacral spinal cord of the adult.

Transecting the thoracic spinal cord of the rat has markedly different effects on behavioral responses of the hindlimbs if the lesion is made at the neonatal or weanling stage of development. The present investigation tested the possibility that the behavioral differences were related to a difference in the distribution or density of dorsal root connections in the lumbosacral spinal cord. In order to use each animal as its own control the distribution and density of dorsal root axons was compared on the two sides of the L5-S1 segments of the lumbosacral spinal cord in adult rats given a mid-thoracic spinal hemisection at the neonatal or weanling stage of development. Comparing the experimental (initially hemisected side) and control sides of the cord, we found no evidence for a change in the distribution of dorsal root axons. The distribution of Fink-Heimer stained degeneration 4--6 days after bilateral spinal root section was virtually identical on the two sides of the cord from animals hemisected at either stage. However, in rats spinally hemisected at the neonatal stage (n = 8), a significantly greater density of dorsal root degeneration was found within the intermediate nucleus of Cajal (INC) on the experimental side using coded material and a blind analysis. No difference in the density of dorsal root degeneration was detected in the group of rats spinally hemisected at the weanling stage (n = 6). Controls indicated that the increased density of degeneration was not due to compression resulting from shrinkage of the INC or to degeneration remaining from the initial hemisection. We conclude that the increased amount of argyrophilia within the INC of neonatally hemisected rats is due to an increased density of dorsal root axons in this zone. This result supports the hypothesis that the behavioral differences found when comparing animals transected at the neonatal or weanling stages of development are related to an increased number of dorsal root connections within the lumbosacral spinal cord.

Age Factors↗
PubMed1976

Increases in collateral axonal growth rostral to a thoracic hemisection in neonatal and weanling rat.

The spinal cords of newborn and weanling rats were hemisected at the mid-thoracic level. Control studies revealed that Fink-Heimer positive debris was absent in the gray matter at three months postoperative. The remaining animals were given a second lesion, a high cervical spinal hemisection, at five to seven months after the original thoracic hemisection. The pattern of degeneration rostal to the thoracic lesion was compared with similar regions of the spinal cord from animals receiving only a cervical hemisection at the adult stage. In neither experimental group of doubly hemisected rats was there any degeneration observed below the thoracic lesion site, even though no glial or connective tissue scar had formed in animals originally operated at birth. Thus no regeneration had occurred. At least one segment above the initial hemisection: 1. the majority of degenerating axons were localized toward the lateral edge of the spinal cord, especially in the doubly lesioned neonatal group; 2. the erae of ipsilateral white matter was reduced more in the neonatal than the weanling operates; 3. there was an upward shift in axonal diameter of ipsilateral fibers in both the region of the rubrospinal tract and the ventrolateral portion of the lateral funiculus of the doubly hemisected rats when compared with the cervically lesioned controls; 4. a significantly greater amount of degeneration was present in lamina VII of Rexed in both the neonatal and weanling experimental operates (p less than 0.05 weanling; p less than 0.001 neonate); 5. no mean difference in area was seen between the ipsilateral and contralateral gray matter in any group for the segments of the spinal cord in which the judgements and measurements were taken. These data suggest that there has been sprouting of axons from descending nerve tracts rostral to the thoracic lesion in both the neonatal and weanling experimental groups. The question remains whether the sprouting of descending nerve tracts is from collateral of axons which normally project rostral to the thoracic hemisection and are not cut by the thoracic lesion (collateral sprouting) or from collaterals of lesioned axons (regenerative sprouting). Present evidence favors collateral sprouting, expecially in the neonatal operate where much retrograde cell death appears to have taken place.

Age Factors↗
PubMed1976

Changes in the magnocellular portion of the red nucleus following thoracic hemisection in the neonatal and adult rat.

The spinal cords of newborn (0-3 day old) and adult rats were mid-thoracically hemisected. Ninety days later a glial and connective tissue scar had formed at the lesion site in the adult hemisected rats while in neonatally lesioned animals only normal appearing regions of the contralateral spinal cord were found in the area of hemisection. Comparisons of the magnocellular portions of the red nucleus (MPRN) revealed a decrease in cell number in the MPRN contralateral (C-MPRN) to the spinal lesion. However, only in the newborn operates was there massive cell loss accompanied by reduction in area and change in shape of the nucleus. These changes were most obvious in the caudal and ventrolateral portions of the C-MPRN. Pooled data from each group of operates indicated that significantly more cells were lost in the C-MPRN in the newborn than in the adult operates (p less than 0.01). Neurons of the C-MPRN which are known to project to the lower cervical and upper thoracic segments of the spinal cord (Brown, '74; Gwyn, '71) remained undamaged after the mid-thoracic hemisection in both groups. However, neurons of this region were enlarged in both groups when compared to a similar region of the ipsilateral MPRN. These neurons were found to be more enlarged in the newborn than in the adult operates (p less than 0.01). This result indicates that massive retrograde cell death takes place after a mid-thoracic hemisection in the neonatal rat. The retrograde degeneration of axotomized neurons partially may explain why CNS regeneration is not found in the immature mammal even though many of the factors thought to limit regeneration in the adult mammal may not be apparent. The increase in cell size of C-MPRN neurons which remain in the neonatal animals after mid-thoracic hemisection may be related to the increase in axonal size found in the region of the rubrospinal tract rostral to the thoracic lesion reported earlier (Prendergast and Stelzner, '76a). Both the increase in axonal and perikaryal size are hypothesized to be related to the increased distribution of supraspinal axons found in the gray matter rostral to a hemisection of the neonatal rat spinal cord.

Age Factors↗